AJP - Regu AJP: Gastrointestinal and Liver Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Regul Integr Comp Physiol 289: R37-R44, 2005. First published February 17, 2005; doi:10.1152/ajpregu.00782.2004
0363-6119/05 $8.00
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
289/1/R37    most recent
00782.2004v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (13)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Li, X.
Right arrow Articles by Choudhry, M. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Li, X.
Right arrow Articles by Choudhry, M. A.

INFLAMMATION AND CYTOKINES

Corticosterone suppresses mesenteric lymph node T cells by inhibiting p38/ERK pathway and promotes bacterial translocation after alcohol and burn injury

Xiaoling Li,1 Shadab N. Rana,1 Elizabeth J. Kovacs,2,3,4,5 Richard L. Gamelli,2,3,4 Irshad H. Chaudry,1 and Mashkoor A. Choudhry1

1Center for Surgical Research and Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama; and 2Alcohol Research Program, 3Burn and Shock Trauma Institute, Departments of 4Surgery and 5Cell Biology, Neurobiology and Anatomy, Loyola University Chicago Medical Center, Maywood, Illinois

Submitted 17 November 2004 ; accepted in final form 11 February 2005


   ABSTRACT
TOP
 ABSTRACT
MATERIAL AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Previous studies showed that alcohol (EtOH) intoxication before burn injury suppresses mesenteric lymph node (MLN) T cell functions and increases gut bacterial translocation. In this study, we examined whether corticosterone (Cort) plays any role in suppressing MLN T cell function and bacterial accumulation after EtOH intoxication and burn injury. Rats were gavaged with EtOH to achieve a blood EtOH level of ~100 mg/dl before receiving 25% total body surface area burn or sham injury. A group of rats was treated with the Cort synthesis inhibitor metyrapone (25 mg/kg) at the time of injury and on day 1 after injury. Two days after injury, a significant increase in blood Cort levels and suppression of MLN T cell proliferation and IL-2 production was observed in rats receiving combined insult of EtOH intoxication and burn injury compared with rats receiving EtOH intoxication or burn injury alone. There was no change in T cell apoptosis after combined insult of EtOH and burn injury. Furthermore, T cell suppression was accompanied by a significant decrease in p38 and ERK1/2 activation (phosphorylation). There was no difference in JNK activation after EtOH and burn injury. Treatment of rats with metyrapone prevented the suppression of MLN T cell proliferation, IL-2 production, and p38 and ERK1/2 phosphorylation. Restoration of T cell function in metyrapone-treated animals was also associated with the decrease in bacterial accumulation in MLN. These findings suggest that EtOH intoxication before burn injury augments Cort release, which suppresses MLN T cell function by inhibiting p38 and ERK1/2 activation and promotes bacterial accumulation in MLN after EtOH and burn injury.

T lymphocyte; mitogen-activated protein kinases; cell signaling; thermal injury

NEARLY ONE MILLION BURN INJURIES are reported every year in the United States (2). Strikingly, alcohol (EtOH) use before injury is apparent in nearly 50% of burn patients (8, 22, 35–38). Furthermore, findings from previous studies suggest that EtOH intoxication at the time of injury plays a significant role in postinjury pathogenesis (8, 35–38, 48). These studies showed that burn patients who sustained injury under the influence of EtOH had significantly longer hospital stays, are more susceptible to infection, and are more likely to die than burn patients who sustained similar burn injury but had not consumed EtOH before injury. The mechanism underlying EtOH-induced increase in postburn morbidity and mortality remains unknown. Findings from experimental studies have shown that acute EtOH intoxication before burn injury impairs delayed type hypersensitivity, produces a greater suppression of mitogen-induced splenic-lymphocyte proliferation, and enhances susceptibility to bacterial infection (10, 18–20, 30, 40). Recent studies from our laboratory (6, 29) have shown that acute EtOH intoxication before burn injury enhances bacterial translocation. The increase in bacterial translocation was accompanied with suppression of intestinal T cell function and increased intestinal permeability (6). Furthermore, our studies suggested a correlation between T cell suppression and a decrease in p38 and ERK1/2 activation (i.e., phosphorylation) in mesenteric lymph node (MLN) T cells after EtOH intoxication and burn injury (11). Our studies collectively suggest that diminished intestinal T cell function and increased intestinal permeability are likely to contribute to increased bacterial translocation after EtOH and burn injury (6, 11, 29). Bacterial translocation has been observed after burn injury in a number of previous studies (4, 7, 16, 23, 24, 27, 47). Furthermore, these studies support the concept that intestine-derived factors including bacteria and their products play significant roles in initiating/exacerbating multiple organ dysfunction in acutely injured patients as well as in patients with EtOH intoxication (5, 8, 15, 20, 32).

To further delineate the mechanism of suppressed T cell responses and increased bacterial translocation, we attempted to determine whether glucocorticoids play any role in these responses. Glucocorticoids are pleiotropic hormones with a wide spectrum of immunomodulatory and anti-inflammatory properties. (3, 8, 18, 21, 39, 49, 50). They function by binding to glucocorticoid receptor, which resides in an inactive form in the cytoplasm of target cells (3, 44, 49). Upon interaction with the hormone, this receptor is transported into the nucleus, where it binds to discrete nucleotide sequences to alter the expression of specific genes. In addition, glucocorticoids are also known to inhibit the activation of mitogen-activated protein kinase (MAPK) pathways (13, 28).

Several lines of evidence suggest that EtOH intoxication and burn injury independently activate the hypothalamic-pituitary-adrenal (HPA) axis (8, 21, 23, 27, 33, 38, 39, 50). Corticosterone (Cort), which is the glucocorticoid end product of the HPA axis in rodents, plays an important role in influencing the immune system. There is evidence that elevated levels of Cort suppress macrophage and T cell functions (1, 2, 21, 23, 42, 46, 49, 50). In contrast, other studies suggest adrenal insufficiency to be the cause of impaired host ability to clear infectious agents (8, 18, 38). Thus the role of Cort after acute injury remains controversial. Because both EtOH intoxication and burn injury result in HPA activation, we tested the hypothesis that EtOH intoxication before burn injury enhances Cort levels, which in turn inhibits MLN T cell proliferation and increases bacterial translocation. Metyrapone, a Cort synthesis inhibitor, was used to block endogenous Cort synthesis. This substance inhibits 11{beta}-hydroxylase, an enzyme responsible for the conversion of deoxycorticosterone, the Cort precursor, to Cort in the adrenal cortex (3). After establishing the role of Cort in T cell suppression, we also examined whether Cort mediates the suppression of T cells by altering the activation of p38, ERK1/2, and/or JNK, members of the MAPK family.


   MATERIAL AND METHODS
TOP
 ABSTRACT
 MATERIAL AND METHODS
RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Animals and reagents. Male Sprague-Dawley rats weighing 225–250 g were obtained from Charles River Laboratories (Wilmington, MA). Nylon wool was obtained from Polysciences (Warrington, PA). Reagents for cell culture were obtained from Fisher Scientific (Atlanta, GA). We used antibodies to p38 protein (catalog no. 9712; NEN Biolabs, Beverly, MA), phospho-p38 (Thr180/Tyr182, catalog no. 9211; NEN Biolabs), ERK1/2 protein (catalog no. 9102; NEN Biolabs), and phospho-ERK1/2 (Thr202/Tyr204, catalog no. 9101; NEN Biolabs). For JNK measurements, we used antibodies to stress-activated protein kinase (SAPK)/JNK protein (catalog no. 9252; NEN Biolabs) and phospho-SAPK/JNK (Thr183/Tyr185, catalog no. 4671). Anti-rat CD3 antibodies were purchased from Pharmingen (San Diego, CA). Reagents for the SDS-PAGE were obtained from Bio-Rad (Richmond, CA). Immobilon P membrane (polyvinylidene difluoride) was obtained from Millipore (Bedford, MA). Protein molecular weight markers were obtained from Invitrogen (Carlsbad, CA). Radioimmunoassay (RIA) kit for Cort measurement was obtained from Diagnostic Products (Los Angeles, CA).

Rat model of acute EtOH and burn injury. As described previously (6), rats were randomly divided into four groups: saline + sham, EtOH + sham, saline + burn, and EtOH + burn. In EtOH-treated groups, the levels of blood EtOH equivalent to 90–100 mg/ml were achieved by gavage feeding of 5 ml of 20% EtOH in saline. In saline groups, animals were gavaged with 5 ml of saline. Four hours after gavage with saline or EtOH, all animals were anesthetized and transferred into a template, which was fabricated to expose 25% of the total body surface. Animals were then immersed in a boiling water bath (95–97°C) for 10 s. Sham-injured rats were subjected to identical anesthesia and immersed in lukewarm water. The animals were dried immediately and given fluid resuscitation (intraperitoneally) with 10 ml physiological saline. Animals were allowed to recover from anesthesia, returned to their cages, and allowed food and water ad libitum. All the experiments were carried out in adherence to the National Institute of Health Guidelines for the Care and Use of Laboratory Animals and were approved by the Institutional Animal Care and Use Committee of the University of Alabama at Birmingham.

Treatment of animals with Cort inhibitor. Metyrapone (25 mg/kg body wt) was administered intraperitoneally at the time of injury and on day 1 after injury.

Measurements of blood Cort levels. Rats were anesthetized, and blood was drawn via cardiac puncture. The level of blood corticosterone was measured using a RIA kit, Coat-A-Count, provided by Diagnostic Products (Los Angeles, CA).

T cell preparation. Rats were anesthetized, and intestine was exposed via midline incision. MLN were removed aseptically. Isolated MLN were gently crushed to prepare single-cell suspension in Hanks' balanced salt solution (HBSS; Fisher Scientific) supplemented with 10 mM HEPES, 50 µg/ml gentamicin, 100 U/ml penicillin, and 100 µg/ml streptomycin. The cell suspension was incubated with nylon wool-packed columns. These columns were preequilibrated with HBSS containing 10 mM HEPES, 50 µg/ml gentamicin, 100 U/ml penicillin, 100 µg/ml streptomycin, and 5% fetal calf serum (FCS). The columns containing cells were incubated at 37°C for 50–60 min. T cells were obtained by eluting the columns with 15 ml of HBSS at a flow rate of 1 drop/s (6, 11).

T cell proliferation. Nylon wool-purified T cells were resuspended at a density of 5 x 106 cells/ml in RPMI 1640 (Fisher Scientific) supplemented with 2 mM L-glutamine, 10 mM HEPES, 50 µg/ml gentamicin, 100 U/ml penicillin, 100 µg/ml streptomycin, and 10% FCS. As described previously (11), 100 µl of T cell suspension was cultured in a 96-well plate at 37°C and 5% CO2 in the presence of anti-CD3 (1 µg/ml). After 66 h of culture, 0.5 µC [3H]thymidine was added to each well containing the cells. After an additional 6 h of incubation, cells were harvested using a PHD Cell Harvester (Cambridge Technology). The incorporation of radiolabeled thymidine was quantified using a liquid scintillation counter, and the data are expressed as disintegrations per minute (dpm).

T cell IL-2 production. Under culture conditions similar to those described for proliferation, T cells were cultured for 48 h; supernatants were harvested and tested for IL-2 production using an ELISA kit (Biosource International, Camarillo, CA).

Measurement of p38, ERK1/2, and JNK protein and phosphorylation levels. As described previously (11), nylon wool-purified T cells were stimulated with anti-CD3 (1 µg/ml) for 5 min and lysed in a lysis buffer. For the analysis of p38 and ERK1/2 protein and phosphorylation, lysates were analyzed using SDS-PAGE and transferred to Immobilon P membranes by using a semidry Trans-Blot system (Bio-Rad). The membranes were saturated with blocking buffer (10 mM Tris, 150 mM NaCl, and 0.05% Tween 20 supplemented with 5% dry milk) for 2 h at room temperature and incubated with the desired antibody at 4°C overnight. The membranes were washed five times with TBST (Tris-buffered saline supplemented with 0.05% Tween 20). The membranes were incubated with a secondary antibody conjugated with horseradish peroxidase for 1 h at room temperature. The membranes were washed five times with TBST and probed using enhanced chemiluminescence dye, and phosphoproteins were autoradiographed.

Measurement of MLN T cell apoptosis. The apoptosis of MLN T cells was analyzed by measuring cytoplasmic histone-associated DNA fragments (mono- and oligonucleosomes) with a cell death detection ELISA kit (Roche Applied Science, Indianapolis, IN). Briefly, nylon wool-purified T cells (1 x 105 cells) were suspended in the incubation buffer (provided in the ELISA kit) for 30 min to lyse cells, and the cytoplasmic fraction was isolated according to the manufacturer's instructions. The level of histone-associated DNA was determined by measuring absorbance at 405/490 nm (ELISA Reader; BioTek Instrument, Winooski, VT). The results are expressed as absorbance.

Measurement of bacterial translocation. As described previously (6), MLN were aseptically removed, and equal quantities of MLN were suspended in 1 ml of sterilized phosphate-buffered saline (PBS) and homogenized in sterile glass tissue grinders. A 10-µl aliquot of MLN homogenate was cultured separately on Tryptic soy agar plates. The agar plates were incubated for 24–48 h at 37°C for bacterial growth. Bacterial colony-forming units were counted. If the plates did not show any bacterial growth up to 48 h, they were considered negative for the presence of bacteria.

Statistical analysis. These data are presented as means ± SE and were analyzed using the ANOVA statistical program. A P value <0.05 between groups was considered statistically significant.


   RESULTS
TOP
 ABSTRACT
 MATERIAL AND METHODS
 RESULTS
DISCUSSION
 GRANTS
 REFERENCES
 
Circulatory levels of Cort. As shown in Fig. 1A, a significant increase in circulatory levels of Cort was observed within 4 h after rats were gavaged with EtOH (194 ± 5 ng/ml) compared with rats gavaged with saline alone (85 ± 1.4 ng/ml). Cort levels were significantly elevated on day 1 (218 ± 27 ng/ml) and day 2 (200 ± 20 ng/ml) in burn-injured rats compared with sham-injured rats gavaged with saline (105 ± 11.5 ng/ml). There was no significant difference in Cort levels between rats receiving either EtOH intoxication (202 ± 38 ng/ml on day 1 and 169 ± 30 ng/ml on day 2) or burn injury alone. However, rats receiving a combined insult of EtOH intoxication and burn injury exhibited a significant elevation in Cort levels (315 ± 27 ng/ml on day 1 and 300 ± 24 ng/ml on day 2) compared with the levels observed after either EtOH intoxication or burn injury alone.



View larger version (22K):
[in this window]
[in a new window]
  		Fig. 1. Plasma levels of corticosterone (Cort) in untreated rats (A) and in rats treated with the Cort synthesis inhibitor metyrapone (B) after ethanol (EtOH) and burn injury. Rats were killed at different time points after EtOH intoxication and burn injury, and blood Cort levels were measured (A). A separate group of experimental rats was injected intraperitoneally with the Cort inhibitor metyrapone (25 mg/kg) at the time of injury and on day 1 after injury. Rats were killed on day 2 after EtOH and burn injury, and blood Cort levels were measured (B). Values are means ± SE from at least 6 animals in each group. *P < 0.05 compared with sham rats gavaged with saline. #P < 0.05 compared with burn-injured rats gavaged with saline and sham rats gavaged with EtOH.

 
In another group of animals, rats were treated with the Cort synthesis inhibitor metyrapone at a dose of 25 mg/kg body wt at the time of injury and on day 1 after injury. Circulatory Cort levels were measured on day 2 after injury. Results as presented in Fig. 1B suggest that treatment of rats with metyrapone significantly lowered the levels of Cort after EtOH and burn injury. Similar treatment did not influence Cort levels in sham-injured rats.

T cell proliferation. As shown in Fig. 2A, there was no change in MLN T cell proliferation in rats receiving EtOH intoxication compared with sham rats receiving saline. MLN T cell proliferation was decreased by 50% on day 2 after burn injury alone compared with sham-injured rats gavaged with saline or EtOH. A more than 75% decrease in MLN T cell proliferation was observed in rats receiving a combined insult of EtOH intoxication and burn injury compared with sham-injured rats gavaged with EtOH or saline. Furthermore, the decrease in MLN T cell proliferation after the combined insult of EtOH intoxication and burn injury was found to be 25% more compared with burn-injured rats gavaged with saline. Treatment of rats with metyrapone attenuated the EtOH- and burn-mediated decrease in MLN T cell proliferation.



View larger version (22K):
[in this window]
[in a new window]
  		Fig. 2. Treatment of rats with the Cort inhibitor metyrapone prevented suppression of mesenteric lymph node (MLN) T cell proliferation (A) and IL-2 production (B) on day 2 after EtOH and burn injury. Metyrapone (25 mg/kg) was injected at the time of injury and on day 1 after injury. For proliferation, MLN T cells (5 x 105 cells/well) were cultured with anti-CD3 (1 µg/ml) for 66 h at 37°C, pulsed with [3H]thymidine (0.5 µCi/well), and incubated for an additional 6 h at 37°C. Incorporation of radiolabeled thymidine into cells was counted and expressed as dpm. IL-2 was measured in supernatants harvested 48 h after T cells (5 x 105 cells/well) were cultured with anti-CD3 (1 µg/ml). Values are means ± SE from 6 animals in each group. *P < 0.05 compared with sham-injured rats gavaged with either saline or EtOH. #P < 0.05 compared with burn rats gavaged with saline.

 
T cell IL-2 production. Similar to proliferation, T cell IL-2 production was also decreased by ~70% in rats receiving a combined insult of EtOH intoxication and burn injury compared with sham-injured rats, regardless of their EtOH intoxication, and by nearly 50% compared with burn-injured rats gavaged with saline (Fig. 2B). Treatment of rats with metyrapone significantly prevented the decrease in MLN IL-2 production after EtOH intoxication and burn injury.

T cell p38, ERK1/2, and JNK phosphorylation. The phosphorylation of p38, ERK1/2, and JNK in T cells with and without anti-CD3 stimulation is shown in Figs. 3, 4, and 5, respectively. In unstimulated T cells, there was no difference in the phosphorylation of p38 (Fig. 3A), ERK1/2 (Fig. 4A), and JNK (Fig. 5A) in T cells obtained from rats receiving a combined insult of EtOH intoxication and burn injury compared with sham rat T cells. The stimulation with anti-CD3 resulted in a significant increase in the phosphorylation of p38, ERK1/2, and JNK in T cells derived from control and experimental animals; however, anti-CD3-mediated p38 (Fig. 3) and ERK1/2 (Fig. 4) phosphorylation was significantly lower in T cells from rats receiving a combined insult of EtOH and burn injury compared with those derived from rats receiving burn injury alone without prior EtOH intoxication or from sham-injured rats. There was no significant difference in JNK protein expression and phosphorylation (Fig. 5, A–C) in T cells derived from rats receiving a combined insult of EtOH and burn injury compared with rats receiving either EtOH intoxication or burn injury alone.



View larger version (31K):
[in this window]
[in a new window]
  		Fig. 3. p38 phosphorylation and protein expression in MLN T cells after EtOH and burn injury. On day 2 postinjury, MLN T cells were isolated (1 x 107 cells/ml), stimulated with anti-CD3 (1 µg/ml) for 5 min, and lysed. Lysates were then analyzed for p38 phosphorylation (p-p38) and protein expression (A). Blots were reprobed for {beta}-actin for equal protein loading in various lanes. p38 blots obtained from 6 animals were analyzed using densitometry, and densitometric values were pooled and are shown as means ± SE in B. In addition, densitometric values for phosphorylation were normalized to the total protein. Normalized values for phosphorylation are shown as means ± SE in C. *P < 0.05 compared with sham rats gavaged with either saline or EtOH. #P < 0.05 compared with burn rats gavaged with saline. ^P > 0.05 compared with sham rats gavaged with saline or EtOH and burn rats gavaged with saline.

 


View larger version (38K):
[in this window]
[in a new window]
  		Fig. 4. ERK1/2 phosphorylation and protein expression in MLN T cells after EtOH and burn injury. On day 2 postinjury, MLN T cells were isolated (1 x 107 cells/ml), stimulated with anti-CD3 (1 µg/ml) for 5 min, and lysed. Lysates were then analyzed for ERK1/2 phosphorylation (p-ERK1/2) and protein expression (A). Blots were reprobed for {beta}-actin for equal protein loading in various lanes. ERK1/2 blots obtained from 6 animals were analyzed using densitometry; densitometric values were pooled and are shown as means ± SE in B. In addition, densitometric values for phosphorylation were normalized to the total protein. Normalized values for phosphorylation are shown as means ± SE in C. *P < 0.05 compared with sham rats gavaged with either saline or EtOH. #P < 0.05 compared with burn rats gavaged with saline. ^P > 0.05 compared with sham rats gavaged with saline or EtOH and burn rats gavaged with saline.

 


View larger version (37K):
[in this window]
[in a new window]
  		Fig. 5. JNK phosphorylation and protein expression in MLN T cells after EtOH and burn injury. On day 2 postinjury, MLN T cells were isolated (1 x 107 cells/ml), stimulated with anti-CD3 (1 µg/ml) for 5 min, and lysed. Lysates were then analyzed for JNK phosphorylation (p-JNK) and protein expression (A). Blots were reprobed for {beta}-actin for equal protein loading in various lanes. JNK blots obtained from 6 animals were analyzed using densitometry; densitometric values were pooled and are shown as means ± SE in B. In addition, densitometric values for phosphorylation were normalized to the total protein. Normalized values for phosphorylation are shown as means ± SE in C.

 
In our results, we observed a tendency of a decrease in total p38 (Fig. 3, A and B) and ERK1/2 (Fig. 4, A and B) protein levels in T cells after a combined insult of EtOH intoxication and burn injury; however, this decrease in total p38 and ERK1/2 protein levels was not found to be significantly different from that observed after either EtOH intoxication or burn injury alone. Nonetheless, we normalized p38 and ERK1/2 phosphorylation by calculating the ratio of phosphorylation to the total protein expression. The results obtained from these ratio analyses suggest a nearly 30% decrease in p38 (Fig. 3C) and ERK1/2 (Fig. 4C) phosphorylation in MLN T cells derived from rats receiving burn injury in the absence of EtOH intoxication compared with sham alone. A nearly 75% decrease in p38 and ERK1/2 phosphorylation was observed in MLN T cells obtained from rats receiving a combined insult EtOH intoxication compared with sham-injured rats regardless of their EtOH intoxication. The decrease in MLN T cell p38 and ERK1/2 phosphorylation after EtOH intoxication and burn injury was found to be ~45% more compared with burn-injured rats gavaged with saline. There was no difference in p38 (Fig. 3C) and ERK1/2 (Fig. 4C) phosphorylation in MLN T cells obtained from sham rats gavaged with EtOH compared with sham rats gavaged with saline.

In a subsequent experiment, a group of sham and EtOH plus burn-injured rats was treated with metyrapone. MLN p38 and ERK1/2 protein and phosphorylation were determined. In these experiments we did not measure JNK because no change was observed in JNK activity after EtOH and burn injury. Results as presented in Fig. 6 show that treatment of rats with metyrapone prevented the suppression in T cell p38 (A) and ERK1/2 (B) phosphorylation observed after EtOH and burn injury. No effect of similar treatment was observed on MLN T cell T p38 and ERK1/2 phosphorylation in sham-injured rats gavaged with saline.



View larger version (30K):
[in this window]
[in a new window]
  		Fig. 6. Treatment of rats with Cort inhibitor metyrapone prevented suppression of p38 (A) and ERK1/2 (B) phosphorylation in MLN T cells after EtOH and burn injury. Metyrapone (25 mg/kg) was injected at the time of injury and on day 1 after injury. On day 2 postinjury, MLN T cells were isolated (1 x 107 cells/ml), stimulated with anti-CD3 (1 µg/ml) for 5 min, and lysed. Lysates were then analyzed for p38 and ERK1/2 phosphorylation. Blots obtained from phosphorylated p38 and ERK1/2 were analyzed using densitometry, and the densitometric values were pooled from 6 animals in each group and are shown as means ± SE. *P < 0.05 compared with other groups. MP, metyrapone.

 
MLN T cell apoptosis. As shown in Fig. 7, there was no difference in T cell apoptosis after a combined insult of EtOH intoxication and burn injury compared with either EtOH intoxication or burn injury alone. Furthermore, the treatment of animals with Cort inhibitor metyrapone did not affect T cell apoptosis in rats receiving a combined insult of EtOH intoxication and burn injury.



View larger version (15K):
[in this window]
[in a new window]
  		Fig. 7. MLN T cell apoptosis after EtOH and burn injury. Rats received sham or burn injury with or without prior EtOH intoxication. A group of EtOH-intoxicated, burn-injured rats was treated with metyrapone (25 mg/kg) at the time of injury and on day 1 after injury. On day 2 postinjury, MLN T cells were isolated (1 x 105 cells/ml), and apoptosis in T cells was determined by measuring cytoplasmic histone-associated DNA fragments using a cell death detection ELISA kit. Values are means ± SE from 4 animals in each group. A405 nm-A490 nm, ratio of absorbance at 405 and 490 nm.

 
Bacterial accumulation. As shown in Fig. 8, there was no change in bacterial accumulation in MLN of sham-injured animals regardless of their EtOH exposure. However, an increase in bacterial accumulation was noted in MLN of rats receiving burn injury alone in the absence of EtOH intoxication. A severalfold increase in bacterial accumulation was observed in MLN of rats receiving a combined insult of EtOH intoxication and burn injury compared with either EtOH intoxication or burn injury alone. Treatment of rats with metyrapone did not influence bacterial accumulation in MLN of sham-injured rats; however, a similar treatment of experimental rats significantly prevented the increase in bacterial accumulation observed after EtOH and burn injury.



View larger version (13K):
[in this window]
[in a new window]
  		Fig. 8. Treatment of rats with Cort inhibitor metyrapone prevented bacterial accumulation in MLN after EtOH and burn injury. Metyrapone (25 mg/kg) was injected at the time of injury and on day 1 after injury. On day 2 postinjury, rats were killed, and MLN were removed aseptically and homogenized. Homogenates (10 µl) were cultured on a nutrient agar plate for 24–48 h at 37°C. Bacterial colonies that appeared on the plates were counted. Values are means ± SE from 6 animals in each group. *P < 0.05 compared with sham rats gavaged with either saline or EtOH. #P < 0.05 compared with burn rats gavaged with saline as well as sham-injured rats regardless of EtOH intoxication.

 

   DISCUSSION
TOP
 ABSTRACT
 MATERIAL AND METHODS
 RESULTS
 DISCUSSION
GRANTS
 REFERENCES
 
In this study, we observed a significant increase in Cort levels after a combined insult of EtOH intoxication and burn injury. This was accompanied with suppression of MLN T cell proliferation and IL-2 production. Treatment of rats with the Cort inhibitor metyrapone prevented the decrease in T cell proliferation and IL-2 production after EtOH and burn injury. The results also suggest that Cort is likely to mediate T cell suppression by inhibiting p38 and ERK1/2 phosphorylation. Furthermore, we found that the restoration of T cell function in metyrapone-treated animals prevented the increase in bacterial accumulation in MLN. These findings collectively suggest that EtOH intoxication preceding burn injury augments the release of Cort and diminishes MLN T cell function, resulting in bacterial multiplication and their accumulation in MLN.

Kawakami et al. (30) have shown that although acute EtOH intoxication does not elevate Cort levels, a similar dose of EtOH given before burn injury augments the serum Cort levels. Consistent with these studies, the present findings suggest that a combined insult of EtOH intoxication and burn injury heightens the releases of Cort, which in turn causes MLN T cell suppression. In contrast, Faunce et al. (18) have shown a somewhat protective role of glucocorticoids after a combined insult of EtOH intoxication and burn injury. These authors (18) observed that whereas the individual insult of EtOH intoxication or burn injury resulted in increased Cort levels, a combination of the two insults (i.e., EtOH intoxication and burn injury) caused a decrease in Cort levels. They also showed that treatment of animals with Cort prevented the splenic T cell suppression following EtOH and burn injury. Although a definitive cause for the observed differences between our study and the study by Faunce et al. (18) is not known, it is possible that the differences in our results are due to factors such as the degree of burn or route of EtOH administration. In this regard, Faunce et al. (18) utilized a mouse model of 15% burn and intraperitoneal EtOH injection, whereas in our studies rats were orally gavaged with EtOH and received a 25% burn injury. It is sufficient to state that the above studies collectively suggest that Cort levels tightly control immune cell functions. Thus any change in Cort levels as low as reported by Faunce et al. (18) or as high as has been shown in many injury conditions (1, 21, 23, 27, 30, 33, 39, 42) is likely to affect the immune response.

In many previous studies, elevated levels of Cort were shown to suppress both macrophage and T cell functions, including IL-2 and IFN-{gamma} production (3, 8, 38, 44). In addition, Cort is also known to cause apoptosis in T and B cells. Although in our study we did not observe T cell apoptosis after a combined insult of EtOH intoxication and burn injury, a role of Cort in increased apoptosis following burn injury was supported in a previous study by Nakanishi et al. (39), who showed that adrenalectomy or treatment of rats with RU486 prevented the burn-induced thymocyte apoptosis. Hawes et al. (23) showed that chronic elevation of Cort for 4 days after burn injury alone or burn injury superimposed with burn wound infection adversely affected body mass and lymphocyte numbers and was correlated with increased mortality. Similarly, elevation in Cort after chronic EtOH intoxication has also been correlated with the loss of CD4+ and CD8+ cells from thymus, spleen, and intestinal lymphoid organs, MLN, and Peyer’s patches (8, 38, 42, 46). Although these findings collectively suggest that elevation of Cort can lead to apoptosis and thereby to T cell function deficits under those conditions, in our study apoptosis was not found to be a cause of decreased T cell proliferation and IL-2 production. Rather, our results indicate that inhibition of p38 and ERK1/2 may be a component of signaling cascade that plays a role in Cort-mediated T cell suppression after a combined insult of EtOH intoxication and burn injury.

In the absence of injury, stimulation of resting cells with mitogen, anti-CD3, or antigen results in the activation of P56lck and P59fyn, which phosphorylate Zap-70 (7, 9, 12, 17, 26). ZAP-70 then phosphorylates phospholipase C-{gamma} (PLC-{gamma}) to hydrolyze phosphatidylinositol 4,5-bisphosphate into D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and diacylglycerol (DAG). Ins(1,4,5)P3 induces the release of Ca2+ from intracellular as well as extracellular stores. DAG, on the other hand, activates PKC, resulting in activation of MAPKs, including p38, ERK1/2, and JNK (17). MAPKs then relay information to the nucleus through another series of downstream signaling molecules, leading to T cell activation. The resultant activated T cells mitotically divide and produce IL-2, which upon release interacts with IL-2 receptor expressed on T cells, leading to proliferation and subsequent cytokine production. Although the role of JNK along with p38 and ERK1/2 has been suggested in T cell proliferation and IL-2 production (17), the present findings suggest that JNK may not be critical to T cell suppression in EtOH- and burn-injured rats, because there was no change in JNK activity after EtOH intoxication and burn injury. Thus the suppression in p38 and ERK1/2 is likely to play a major role in Cort-mediated suppression of T cell proliferations and IL-2 production after a combined insult of EtOH intoxication and burn injury. Previous studies from our laboratory and others have shown that T cell dysfunction during burn and sepsis is accompanied with alterations in P59fyn kinase activity, PKC, and Ca2+ signaling (7, 8, 9, 12, 25). Because the activation of P59fyn and Ca2+ signaling precedes p38 and ERK1/2 activation, alterations in either of these pathways may potentially contribute to a suppression of p38 and ERK1/2 in T cells in EtOH and burn injury. However, a more direct effect of Cort on p38 and ERK1/2 is not ruled out. Although the mechanism by which Cort suppresses p38 and ERK1/2 in T cells after EtOH and burn injury remains to be established, previous studies in other cells have shown that Cort upregulates MAPK phosphatase, which in turn leads to inhibition of p38 and ERK1/2 activity (13, 28). This in turn results in decreased T cell proliferation and IL-2 production.

Our results support the suggestion that Cort-mediated inhibition of T cell functions is likely to contribute to increased bacterial accumulation in MLN after EtOH intoxication and burn injury. Previous studies have shown that administration of dexamethasone in healthy animals impairs IgA synthesis and increases bacterial translocation (1). Furthermore, other reports have indicated that elevations in Cort following burn wound sepsis prolongs the survival of translocated bacteria in the MLN of rats (23, 27). The role of other hormones in pathogenesis of infectious diseases and, in particular, enteric infections was described recently (34). These reports suggest that products of HPA can directly influence growth and virulence of bacteria. In a recent study, catecholamines were shown to promote growth of Escherichia coli (34). However, whether glucocorticoids directly affect bacterial growth or virulence in EtOH and burn injury remains unknown. It is also likely that elevated Cort levels following a combined insult of EtOH and burn injury may impair normal intestinal peristalsis by promoting stasis. Impaired peristalsis is associated with increased bacterial growth and their translocation in both human beings and animals.

The fact that T cell-mediated immunity is critical to defense against bacterial infection, including the bacteria derived from intestine, is supported by many previous studies (8, 14, 31, 38, 45). Sibley and Jerrells (46) have shown that the loss of lymphoid cells after chronic EtOH abuse diminishes host resistance to enteric pathogens. Others have suggested that adoptive transfer of T cells provides protection against a number of bacterial infections (43). In addition, previous studies have shown an increase in spontaneous bacterial translocation from intestine to extraintestinal organs in athymic homozygous (nu/nu) nude mice compared with heterozygous strains (nu/+) (41). Furthermore, recent findings from our laboratory have shown that depletion of T cells in healthy rats resulted in increased bacterial accumulation in MLN (6). A similar T cell depletion in EtOH- and burn-injured rats further enhanced bacterial accumulation in MLN and in other distant organs, including spleen and blood (6). Bacterial translocation is an ongoing process, and in healthy conditions, a few bacteria are known to translocate to MLN. However, these bacteria do not survive because of intact immune defense, and, thus, MLN from healthy animals remains relatively sterile. Because T cell-mediated immunity is critical to defense against enteric bacteria, impaired MLN T cell function as observed after EtOH and burn injury would be expected to contribute to a decrease in bacterial clearance and an increase in bacterial multiplication, resulting in their accumulation.

In summary, our present results suggest that EtOH intoxication prior to burn injury augments Cort release, which in turn suppresses T cell function by inhibiting p38 and ERK pathway. This leads to increased bacterial accumulation in MLN. MLN is the central lymph node that connects various parts of the intestine and therefore plays a critical role in clearing bacteria originating from the intestine. Thus any alterations in MLN T cell function may impair the local immune defense, resulting in bacterial multiplication and accumulation in MLN.


   GRANTS
TOP
 ABSTRACT
 MATERIAL AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
REFERENCES
 
This study was supported by National Institute on Alcohol Abuse and Alcoholism Grants AA-12901 (to M. A. Choudhry) and AA-12034 (to E. J. Kovacs).


   FOOTNOTES
 

Address for reprint requests and other correspondence: M. A. Choudhry, Center for Surgical Research, Univ. of Alabama at Birmingham, VolkerHall G 094, 1670 Univ. Boulevard, Birmingham, AL 35294 (E-mail: mashkoor.choudhry{at}ccc.uab.edu)

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.


   REFERENCES
TOP
 ABSTRACT
 MATERIAL AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 

  1. Alverdy J and Aoys E. The effect of glucocorticoid administration on bacterial translocation: evidence for an acquired mucosal immunodeficient state. Ann Surg 214: 719–723, 1991.[ISI][Medline]
  2. American Burn Association. Burn incidence and treatment in the US: 2000 fact sheet. Available at http://www.ameriburn.org/pub/BurnincIdenceFactSheet.htm.
  3. Ashwell JD, Liu FWM, and Vacchio MS. Glucocorticoids in T cell development and function. Annu Rev Immunol 18: 309–345, 2000.[CrossRef][ISI][Medline]
  4. Baron P, Traber LD, Traber DL, Nguyen T, Hollyoak M, Heggers JP, and Herndon DN. Gut failure and translocation following burn and sepsis. J Surg Res 57: 197–204, 1994.[CrossRef][ISI][Medline]
  5. Bode C and Bode JC. Effect of alcohol consumption on the gut. Best Pract Res Clin Gastroenterol 17: 575–592, 2003.[CrossRef][Medline]
  6. Choudhry MA, Fazal N, Goto M, Gamelli RL, and Sayeed MM. Gut-associated lymphoid T cell suppression enhances bacterial translocation in alcohol and burn injury. Am J Physiol Gastrointest Liver Physiol 282: G937–G947, 2002.[Abstract/Free Full Text]
  7. Choudhry MA, Fazal N, Namak SY, Haque F, Ravindranath T, and Sayeed MM. PGE2 suppresses intestinal T cell function in thermal injury: a cause of enhanced bacterial translocation. Shock 16: 183–188, 2001.[ISI][Medline]
  8. Choudhry MA, Gamelli RL, and Chaudry IH. Alcohol abuse: a major contributing factor to post burn/trauma immune complications. In: Yearbook of Intensive Care and Emergency Medicine, edited by Vincent J-L. New York: Springer, 2004, p. 15–26.
  9. Choudhry MA, Hockberger PE, and Sayeed MM. PGE2 suppresses mitogen-induced Ca2+ mobilization in T cells. Am J Physiol Regul Integr Comp Physiol 277: R1741–R1748, 1999.[Abstract/Free Full Text]
  10. Choudhry MA, Messingham KA, Namak S, Colantoni A, Fontanilla CV, Duffner LA, Sayeed MM, and Kovacs EJ. Ethanol exacerbates T cell dysfunction after thermal injury. Alcohol 21: 239–243, 2000.[CrossRef][ISI][Medline]
  11. Choudhry MA, Ren X, Romero A, Kovacs EJ, Gamelli RL, and Sayeed MM. Combined alcohol and burn injury differentially regulate p-38 and ERK activation in mesenteric lymph node T cell. J Surg Res 121: 62–68, 2004.[CrossRef][ISI][Medline]
  12. Choudhry MA, Uddin S, and Sayeed MM. Prostaglandin E2 modulation of p59fyn tyrosine kinase in T lymphocytes during sepsis. J Immunol 160: 929–935, 1998.[Abstract/Free Full Text]
  13. Clark AR and Lasa M. Crosstalk between glucocorticoids and mitogen-activated protein kinase signalling pathways. Curr Opin Pharmacol 3: 404–411, 2003.[CrossRef][ISI][Medline]
  14. Cook RT. Alcohol abuse, alcoholism, and damage to the immune system-a review. Alcohol Clin Exp Res 22: 1927–1942, 1998.[ISI][Medline]
  15. Deitch EA. Role of the gut lymphatic system in multiple organ failure. Curr Opin Crit Care 7: 92–98, 2001.[CrossRef][Medline]
  16. Deitch EA, Winterton J, and Berg R. Thermal injury promotes bacterial translocation from the gastrointestinal tract in mice with impaired T-cell-mediated immunity. Arch Surg 121: 97–101, 1986.[Abstract]
  17. Dong C, Davis RJ, and Flavell RA. MAP kinases in the immune response. Annu Rev Immunol 20: 55–72, 2002.[CrossRef][ISI][Medline]
  18. Faunce DE, Gregory MS, and Kovacs EJ. Glucocorticoids protect against suppression of T cell responses in a murine model of acute ethanol exposure and thermal injury by regulating IL-6. J Leukoc Biol 64: 724–732, 1998.[Abstract]
  19. Faunce DE, Gregory MS, and Kovacs EJ. Effects of acute ethanol exposure on cellular immune responses in a murine model of thermal injury. J Leukoc Biol 62: 733–740, 1997.[Abstract]
  20. Fukushima R, Alexander JW, Gianotti L, Pyles T, and Ogle CK. Bacterial translocation-related mortality may be associated with neutrophil-mediated organ damage. Shock 3: 323–328, 1995.[ISI][Medline]
  21. Fukuzuka K, Edwards CK III, Clare-Salzler M, Copeland EM III, Moldawer LL, and Mozingo DW. Glucocorticoid-induced, caspase-dependent organ apoptosis early after burn injury. Am J Physiol Regul Integr Comp Physiol 278: R1005–R1018, 2000.[Abstract/Free Full Text]
  22. Gentilello LM, Cobean RA, Walker AP, Moore EE, Wertz MJ, and Dellinger EP. Acute ethanol intoxication increases the risk of infection following penetrating abdominal trauma. J Trauma 34: 669–674, 1993.[ISI][Medline]
  23. Hawes AS, Richardson RP, Antonacci AC, and Calvano SE. Chronic pathophysiologic elevation of corticosterone after thermal injury or thermal injury and burn wound infection adversely affects body mass, lymphocyte numbers, and outcome. J Burn Care Rehabil 16: 1–15, 1995.[CrossRef][Medline]
  24. Herndon DN and Zeigler ST. Bacterial translocation after thermal injury. Crit Care Med 21: S50–S54, 1993.[ISI][Medline]
  25. Hoyt DB, Junger WG, Loomis WH, and Liu FC. Effects of trauma on immune cell function: impairment of intracellular calcium signaling. Shock 2: 23–28, 1994.[ISI][Medline]
  26. Huang Y and Wange RL. T cell receptor signaling: beyond complex complexes. J Biol Chem 279: 28827–28830, 2004.[Free Full Text]
  27. Jones WG II, Minei JP, Richardson RP, Fahey TJ III, Calvano SE, Antonacci AC, Shires GT III, and Shires GT. Pathophysiologic glucocorticoid elevations promote bacterial translocation after thermal injury. Infect Immun 58: 3257–3261, 1990.[Abstract/Free Full Text]
  28. Kassel O, Sancono A, Kratzschmar J, Kreft B, Stassen M, and Cato AC. Glucocorticoids inhibit MAP kinase via increased expression and decreased degradation of MKP-1. EMBO J 20:7108–7116, 2001.[CrossRef][ISI][Medline]
  29. Kavanaugh MJ, Clark C, Goto M, Kovacs EJ, Gamelli RL, Sayeed MM, and Choudhry MA. Effect of acute alcohol ingestion prior to burn injury on intestinal bacterial growth and barrier functions. Burns 31: 290–296, 2004.
  30. Kawakami M, Switzer BR, Herzog SR, and Meyer AA. Immune suppression after acute ethanol ingestion and thermal injury. J Surg Res 51: 210–215, 1991.[CrossRef][ISI][Medline]
  31. Kerksiek KM and Pamer EG. T cell responses to bacterial infection. Curr Opin Immunol 11: 400–405, 1999.[CrossRef][ISI][Medline]
  32. Keshavarzian A, Holmes EW, Patel M, Iber F, Fields JZ, and Pethkar S. Leaky gut in alcoholic cirrhosis: a possible mechanism for alcohol-induced liver damage. Am J Gastroenterol 94: 200–207, 1999.[CrossRef][ISI][Medline]
  33. Lang CH, Nystrom GJ, and Frost RA. Burn-induced changes in IGF-I and IGF-binding proteins are partially glucocorticoid dependent. Am J Physiol Regul Integr Comp Physiol 282: R207–R215, 2002.[Abstract/Free Full Text]
  34. Lyte M. Microbial endocrinology and infectious disease in the 21st century. Trends Microbiol 12: 14–20, 2004.[CrossRef][ISI][Medline]
  35. Maier RV. Ethanol abuse and the trauma patient. Surg Infect (Larchmt) 2: 133–141, 2001.[Medline]
  36. McGill V, Kowal-Vern A, Fisher SG, Kahn S, and Gamelli RL. The impact of substance use on mortality and morbidity from thermal injury. J Trauma 38: 931–934, 1995.[ISI][Medline]
  37. McGwin G Jr, Chapman V, Rousculp M, Robison J, and Fine P. The epidemiology of fire-related deaths in Alabama, 1992–1997. J Burn Care Rehabil 21: 75–83, 2000.[ISI][Medline]
  38. Messingham KA, Faunce DE, and Kovacs EJ. Alcohol, injury, and cellular immunity. Alcohol 28: 137–149, 2002.[CrossRef][ISI][Medline]
  39. Nakanishi T, Nishi Y, Sato EF, Ishii M, Hamada T, and Inoue M. Thermal injury induces thymocyte apoptosis in the rat. J Trauma 44: 143–148, 1998.[ISI][Medline]
  40. Napolitano LM, Koruda MJ, Zimmerman K, McCowan K, Chang J, and Meyer AA. Chronic ethanol intake and burn injury: evidence for synergistic alteration in gut and immune integrity. J Trauma 38: 198–207, 1995.[ISI][Medline]
  41. Owens WE and Berg RD. Bacterial translocation from the gastrointestinal tract of athymic (nu/nu) mice. Infect Immun 27: 461–467, 1980.[Abstract/Free Full Text]
  42. Padgett EL, Sibley DA, and Jerrells TR. Effect of adrenalectomy on ethanol-associated changes in lymphocyte cell numbers and subpopulations in thymus, spleen and gut associated lymphoid tissues. Int J Immunopharmacol 22: 285–298, 2000.[CrossRef][ISI][Medline]
  43. Rakhmilevich AL. Evidence for a significant role of CD4+ T cells in adoptive immunity to Listeria monocytogenes in the liver. Immunology 82: 249–254, 1994.[ISI][Medline]
  44. Rook GA. Glucocorticoids and immune function. Baillieres Best Pract Res Clin Endocrinol Metab 13: 567–581, 1999.[CrossRef][Medline]
  45. Schwacha MG and Chaudry IH. The cellular basis of post-burn immunosuppression: macrophages and mediators. Int J Mol Med 10: 239–243, 2002.[ISI][Medline]
  46. Sibley D and Jerrells TR. Alcohol consumption by C57BL/6 mice is associated with depletion of lymphoid cells from the gut-associated lymphoid tissues and altered resistance to oral infections with Salmonella typhimurium. J Infect Dis 182: 482–489, 2000.[CrossRef][ISI][Medline]
  47. Sir O, Fazal N, Choudhry MA, Gamelli RL, and Sayeed MM. Neutrophil depletion prevents intestinal mucosal permeability alterations in burn-injured rats. Am J Physiol Regul Integr Comp Physiol 278: R1224–R1231, 2000.[Abstract/Free Full Text]
  48. Szabo G. Monocytes, alcohol use, and altered immunity. Alcohol Clin Exp Res 22, Suppl: 216s–219s, 1998.
  49. Webster JI, Tonelli L, and Sternberg EM. Neuroendocrine regulation of immunity. Annu Rev Immunol 20: 125–163, 2002.[CrossRef][ISI][Medline]
  50. Wu WJ and Pruett SB. Involvement of catecholamines and glucocorticoids in ethanol-induced suppression of splenic natural killer cell activity in a mouse model of binge drinking. Alcohol Clin Exp Res 21: 1030–1036, 1997.[CrossRef][ISI][Medline]



This article has been cited by other articles:


Home page
 J. Leukoc. Biol.Home page
M. D. Bird and E. J. Kovacs
Organ-specific inflammation following acute ethanol and burn injury
J. Leukoc. Biol., September 1, 2008; 84(3): 607 - 613.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
T. Suzuki, T. Shimizu, H.-P. Yu, Y.-C. Hsieh, M. A. Choudhry, and I. H. Chaudry
Salutary effects of 17beta-estradiol on T-cell signaling and cytokine production after trauma-hemorrhage are mediated primarily via estrogen receptor-{alpha}
Am J Physiol Cell Physiol, June 1, 2007; 292(6): C2103 - C2111.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Lung Cell. Mol. Physiol.Home page
X. Li, E. J. Kovacs, M. G. Schwacha, I. H. Chaudry, and M. A. Choudhry
Acute alcohol intoxication increases interleukin-18-mediated neutrophil infiltration and lung inflammation following burn injury in rats
Am J Physiol Lung Cell Mol Physiol, May 1, 2007; 292(5): L1193 - L1201.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Gastrointest. Liver Physiol.Home page
T. A. Markel, P. R. Crisostomo, M. Wang, C. M. Herring, T. Lahm, K. K. Meldrum, K. D. Lillemoe, F. J. Rescorla, and D. R. Meldrum
Iron chelation acutely stimulates fetal human intestinal cell production of IL-6 and VEGF while decreasing HGF: the roles of p38, ERK, and JNK MAPK signaling
Am J Physiol Gastrointest Liver Physiol, April 1, 2007; 292(4): G958 - G963.
[Abstract] [Full Text] [PDF]

Home page
 J. Leukoc. Biol.Home page
X. Li, S. N. Rana, M. G. Schwacha, I. H. Chaudry, and M. A. Choudhry
A novel role for IL-18 in corticosterone-mediated intestinal damage in a two-hit rodent model of alcohol intoxication and injury
J. Leukoc. Biol., August 1, 2006; 80(2): 367 - 375.
[Abstract] [Full Text] [PDF]

Home page
 J. Leukoc. Biol.Home page
X. Li, M. G. Schwacha, I. H. Chaudry, and M. A. Choudhry
A role of PP1/PP2A in mesenteric lymph node T cell suppression in a two-hit rodent model of alcohol intoxication and injury
J. Leukoc. Biol., March 1, 2006; 79(3): 453 - 462.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
289/1/R37    most recent
00782.2004v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (13)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Li, X.
Right arrow Articles by Choudhry, M. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Li, X.