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antibody
therapy in Dahl S rats
1 Medical College of Wisconsin, Department of Physiology, Milwaukee, Wisconsin 53226; and 2 Genzyme Corporation, Framingham, Massachusetts 01701
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ABSTRACT |
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 TOP
 ABSTRACT
 INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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This study examined the role of
transforming growth factor-
(TGF-) in the development of
hypertension and renal disease in 9-wk-old male Dahl salt-sensitive
(Dahl S) rats fed an 8% NaCl diet for 3 wk. The rats received an
intraperitoneal injection of a control or an anti-TGF- antibody
(anti-TGF- Ab) every other day for 2 wk. Mean arterial pressure was
significantly lower in Dahl S rats treated with anti-TGF- Ab
(177 ± 3 mmHg, n = 12) than in control rats
(190 ± 4 mmHg, n = 17). Anti-TGF- Ab therapy also reduced proteinuria from 226 ± 20 to 154 ± 16 mg/day.
Renal blood flow, cortical blood flow, and creatinine clearance were not significantly different in control and treated rats; however, medullary blood flow was threefold higher in the treated rats than in
the controls. Despite the reduction in proteinuria, the degree of
glomerulosclerosis and renal hypertrophy was similar in control and
anti-TGF- Ab-treated rats. Renal levels of TGF-1 and -2,
-actin, type III collagen, and fibronectin mRNA decreased in rats
treated with anti-TGF- Ab. To examine whether an earlier intervention with anti-TGF- Ab would confer additional
renoprotection, these studies were repeated in a group of 6-wk-old Dahl
S rats. Anti-TGF- Ab therapy significantly reduced blood pressure,
proteinuria, and the degree of glomerulosclerosis and renal medullary
fibrosis in this group of rats. The results indicate that anti-TGF-
Ab therapy reduces blood pressure, proteinuria, and the renal injury associated with hypertension.
blood pressure; proteinuria; glomerulus; kidney; renal
hemodynamics; glomerulosclerosis; transforming growth factor-
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INTRODUCTION |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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TRANSFORMING GROWTH
FACTOR- (TGF-) is a multifunctional cytokine with
profibrogenic properties that has been implicated in the pathogenesis
of renal, cardiac, and vascular end organ damage associated with
hypertension and diabetes. TGF-'s fibrogenic actions result from
its ability to simultaneously increase the deposition of extracellular
matrix proteins (24), decrease the degradation of matrix
proteins (7), and upregulate the expression of integrins,
which facilitate matrix assembly (1). Several lines of
evidence indicate that TGF- may play a role in the pathogenesis of
renal disease associated with diabetes and hypertension (1, 15,
17, 38, 40). In this regard, circulating and/or local concentrations of TGF- in the kidney have been reported to be elevated in humans and experimental animals with glomerulonephritis, diabetic nephropathy, and hypertensive glomerular injury
(1). Moreover, transgenic animals that overexpress TGF-
develop glomerular lesions and tubulointerstitial renal disease that
resemble the types of lesions seen in patients with diabetes or
hypertension (2, 17-19, 24).
There is also evidence that the renal production of TGF- may be
stimulated by elevations in dietary salt intake. This may have clinical
implications and contribute to the renal, cardiac, and vascular damage
that accompanies the development of salt-sensitive forms of
hypertension. In this regard, Ying and Sanders (39) reported that elevations in dietary salt intake increase TGF-1, -2, and -3 mRNA levels in the kidneys of Sprague-Dawley rats. Other investigators found that a high-salt diet increases the levels of
TGF- mRNA and protein in the kidneys and the heart of spontaneously
hypertensive rats (SHR) and Wistar-Kyoto rats and that is associated
with cardiac and renal hypertrophy and fibrosis (40).
Similarly, in Dahl salt-sensitive (Dahl S) rats, which rapidly develop
severe proteinuria and glomerulosclerosis when fed a high-salt diet
(3, 32, 35), Tamaki and coworkers (36)
reported that the renal levels of TGF- mRNA are markedly increased.
However, the contribution of TGF- to the development of
hypertension-induced renal disease remains to be established, because
no studies have examined the effects of chronic blockade of the
production of TGF- in any model of hypertension. Part of the problem
has been due to the lack of inhibitors or molecular approaches to
effectively block this pathway.
Recently, Han et al. (11) and Ziyadeh et al.
(41) reported that knockdown of the production of TGF-
with antisense TGF-1 oligodeoxynucleotides or blockade of the
actions of TGF- with a neutralizing Ab prevented the overexpression
of TGF-, the increase in urinary microalbumin excretion, and the
degree of glomerulosclerosis and the mesangial matrix expansion in the
glomerulus of diabetic db/db mice. The purpose of
the present study was to use a similar approach to examine the effects
of chronic administration of a murine monoclonal antibody 1D11 that
neutralizes all isoforms of TGF- (5) on the development
of hypertension, proteinuria, glomerulosclerosis, and
tubulointerstitial disease in Dahl S rats fed a high-salt (8.0% NaCl) diet.
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METHODS |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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General Methods
Experiments were performed on male Dahl salt-sensitive SS/Jr (Dahl S) rats obtained from a colony maintained at the Medical College of Wisconsin. The rats were housed in an American Association for Accreditation of Laboratory Animal Care-approved animal care facility at the Medical College of Wisconsin, and all protocols were approved by the Medical College of Wisconsin's Institutional Animal Care and Use Committee. The rats were fed a low-salt diet (0.1% NaCl) until the time of the experiment to maintain normal blood pressure and minimize renal injury. Water was allowed ad libitum throughout the study. When rats were 9 wk of age (250-300 g), they were switched to a high-salt diet (8% NaCl) for 3 wk. Experiments were performed using four groups of rats. After 1 wk on the high-salt diet, one group of rats received an intraperitoneal injection of a murine anti-TGF-
monoclonal Ab (1D11) at a dose of 5.0 mg/kg every other day for 2 wk.
The second group received a lower dose (0.50 mg/kg) of the anti-TGF-
Ab every other day for 2 wk. The third group served as the controls and
received an intraperitoneal injection of an isotype-matched control
murine monoclonal antibody (13C4; antiverotoxin) for 2 wk. A fourth
group of rats was maintained on the low-salt diet (0.4% NaCl)
throughout the study so that the degree of baseline renal damage in
age-matched nonhypertensive Dahl S rats could be determined. The
anti-TGF- Ab (1D11) that was used in the present study neutralizes
all three isoforms of TGF- (5) and has a circulating
half-life of 15.2 h in rats.
Protocol 1: Effect of Anti-TGF- Ab Therapy on Blood Pressure
and Renal Function
Measurement of blood pressure in conscious animals. During the second week on the high-salt diet, the rats were anesthetized with an intramuscular injection of ketamine (40 mg/kg), xylazine (2.5 mg/kg), and acepromazine (0.6 mg/kg). An indwelling catheter was inserted into the femoral artery for continuous measurement of mean arterial pressure (MAP). The catheter was tunneled subcutaneously to the back of the neck, fed through a Dacron-mesh button sutured beneath the skin, and advanced through a stainless steel spring that was connected to a swivel (Instech Laboratories: Plymouth Meeting, PA) mounted above the animal's cage. The rats were allowed 1 wk to recover from surgery. Then, MAP and heart rate (HR) were recorded at a sample rate of 300 Hz between 1:00 and 5:00 PM on four consecutive days while the rats were conscious in their home cages. Systolic, diastolic, and MAP were averaged over 1-min periods and converted to a mean value for the recording session. The daily averages of MAP for each animal were reduced to a single value for the 4-day recording period. After the last blood pressure recording session, an overnight urine sample and a blood sample were collected for measurement of proteinuria and urinary creatinine clearance. The protein concentration of the urine samples was determined using the Bradford method (Bio-Rad Laboratories, Hercules, CA).
Measurement of renal hemodynamics in anesthetized animals. At the end of the chronic study, the rats were anesthetized with an intramuscular injection of ketamine (30 mg/kg) and an intraperitoneal injection of thiobutabarbitol (Inactin, 50 mg/kg). The rats were placed on a thermostatically controlled warming table to maintain body temperature at 37°C. After rats were tracheotomized, catheters were inserted into the external jugular vein for intravenous infusions and the femoral artery for measurement of MAP. A 2-mm flow probe was positioned around the left renal artery to measure renal blood flow (RBF) using an electromagnetic flowmeter (Carolina Instruments, King, NC). The rats received an intravenous infusion of a 0.9% NaCl solution containing 1% BSA at a rate of 6 ml/h throughout the experiment to replace fluid losses. After a 30-min stabilization period, cortical blood flow (CBF) was measured from five different sites on the renal cortex using an external probe (PF-316) and a laser-Doppler flowmeter (Pf3, Perimed, Stockholm, Sweden). Medullary blood flow (MBF) was measured using an acutely implanted fiber optic probe, as we have previously described (13).
Histological evaluation of kidneys.
At the end of the acute experiment, the kidneys were rapidly removed
without occluding the blood supply to prevent capillary collapse, and
kidney weights were recorded. The right kidney was frozen in liquid
nitrogen and stored at 
80°C for measurement of the levels of
fibronectin, type III collagen, and TGF-1 and TGF-2 mRNA levels
using RNase protection assays (RPAs). The left kidney was hemisected,
rinsed in ice-cold saline to remove blood, and immersion fixed in a 5%
buffered formalin solution. The fixed kidneys were later embedded in
paraffin, sectioned, and stained with both periodic acid-Schiff
(PAS) and Mason's trichrome stains for light microscopy.
Glomerular diameters were measured using a video microscopy system, and
the degree of matrix expansion and glomerular injury was assessed on a
minimum of 20-40 glomeruli/section as originally described by Raij
et al. (30). The degree of sclerosis was scored on a
0-4 scale based on the percentage of glomerular capillary area
replaced with extracellular matrix. A glomerular sclerosis score of two
indicates that 50% of glomerular capillary area is filled in with
matrix, whereas a score of four indicates complete closure of all
capillaries within a given glomerulus (30). To prevent
sampling bias since glomerular injury is regional in the kidney of Dahl
S rats, we systematically scored every glomeruli found within 2 mm of
the cortical surface as the kidney was scanned from the upper to lower
pole of the section. The kidney sections were also examined for the
degree of fibrosis of vasa recta capillaries and the formation of
protein casts in tubules in the outer medulla. The percentage of
medullary area occupied by protein casts was determined using a
Metamorph imaging program on at least 10 regions per kidney section.
RPA for Fibronectin, Type III Collagen, and TGF-1 and TGF-2
mRNA
Preparation of the riboprobes.
RPA probe templates were prepared by RT-PCR of RNA isolated from
the kidney using primers that are complementary to the cDNA sequences
of fibronectin (26), collagen type III (9),
TGF-1 (6), and TGF-2 (20). The
linearized cDNAs were transcribed in vitro using the Maxiscript kit
(Ambion, Austin, TX) according to the manufacturer's instructions. T7
polymerase and [32P]CTP (3,000 Ci/mmol; DuPont-NEN,
Boston, MA) were included in the reaction mixture to generate
32P-labeled riboprobes. The reaction mixture was incubated
for 60 min at 37°C, and the cDNA templates were removed by digestion with 0.5 U RNase-free DNase. Full-length RNA probes were purified from
the transcription reaction by electrophoresis on 6% polyacrylamide gel, followed by autoradiography, excision of the bands from the gel,
and passive diffusion of the probes into an elution buffer (Maxiscript
kit) overnight at 37°C. The activity of the probe was quantified by
scintillation counting.
RPAs.
RNA from the whole kidney was isolated using the RNAqueous kit
(Ambion). RPAs were performed using the HybSpeed RPA kit (Ambion) according to the manufacturer's instructions. Briefly, radiolabeled antisense RNA probe for fibronectin, collagen III, TGF-1, and TGF-2 were combined with 10 µg of total cellular RNA and
hybridized. A probe for 18s RNA (Ambion) was also included in the
hybridizations to normalize for the amount of RNA added. After
hybridization, RNase A/RNase T1 mix was added to the reactions to
degrade unhybridized RNA. Hybridized RNA was separated from smaller
digested fragments by electrophoresis on a polyacrylamide gel and
visualized by using a phosphorimager. The intensity of the bands
corresponding to protected fibronectin, collagen III, and TGF-1 and
TGF-2 mRNA fragments was quantified using Mac BAS version 2.4 software. The expression of each gene was corrected by dividing probe
specific signal by that obtained for a protected 18s RNA fragment.
Immunohistochemistry.
Unstained 3-µm-thick paraffin sections were deparaffinized, hydrated,
and treated with hyaluronidase (1 mg/ml sodium acetate buffer, pH 5.5, with 0.85% NaCl) for 30 min at 20°C and then washed with
Tris-buffered saline (TBS). Incubation with a nonspecific protein-blocking agent was performed according to the manufacturer's instructions (Elite Vectastain Kit, Vector Laboratories, Burlingame, CA). The sections were incubated overnight at 4°C with 1 µg/ml primary Ab (monoclonal anti--smooth actin, Sigma, St. Louis, MO),
washed at room temperature with TBS and incubated with biotinylated anti-mouse immunoglobin (Vector Laboratories) for 1 h at 20°C. After an extensive wash, the sections were incubated with
avidin-biotin-peroxidase complex for 30 min at 20°C and developed
according to the manufacturer's recommendations. The slides were
counterstained with hematoxylin and viewed at ×400.
Immunohistochemistry for TGF-1 and TGF-2.
Unstained 3-µm-thick paraffin sections were deparaffinized and placed
in Dako targeting retrieval solution at 95°C for 90 min (Dako
Industries, Carpinteria, CA) and then at 20°C for 20 min. Sections
were blocked with 1% BSA for 30 min at 20°C. The slides were then
incubated with a rabbit polyoclonal TGF- primary Ab 1:200 (Santa
Cruz, Santa Cruz, CA) for 90 min at 20°C. Sections were washed with
0.05 M TBS and incubated with a goat-anti-rabbit IgG FITC-conjugated
secondary Ab for 60 min at 20°C (1:100, Santa Cruz). The slides were
washed with TBS (pH 7.6, 0.5 M) and distilled H2O,
counterstained with Evan's blue (0.002%) for 10 min at 20°C, and
viewed at ×400.
Protocol 2: Early Intervention With Anti-TGF- Ab Therapy
General methods.
To determine whether earlier treatment of Dahl S rats with the
anti-TGF- Ab therapy would confer additional renoprotection, experiments were repeated on younger male Dahl S rats that were 6 wk of
age (175-200 g) at the start of the study. The rats were divided
into three groups. One group received an intraperitoneal injection of
anti-TGF- Ab (1D11) (0.50 mg/kg) every other day for 3 wk, while the
control group received an intraperitoneal injection of the
antiverotoxin control Ab (13C4). A third group of rats was maintained
on a low-salt diet (0.1% NaCl) for the duration of the experiment to
determine the baseline degree of glomerulosclerosis in age-matched,
nonhypertensive Dahl S rats.
Time course of the development of proteinuria.
An overnight control urine sample was collected while the rats were on
a low-salt diet (0.1% NaCl). Then, urine samples were collected from
the control rats and anti-TGF- Ab-treated rats on days 4,
11, 18, and 21 after being placed on a
high-salt diet (8.0% NaCl). The protein concentration of the urine
samples was determined using the Bradford method (Bio-Rad
Laboratories). Urinary albumin concentration was determined by the
albumin blue 580 method (Molecular Probes).
Measurement of blood pressure. At the end of the 3-wk study, the rats were anesthetized with ketamine (30 mg/kg im) and thiobutabarbitol (Inactin, 50 mg/kg ip) and placed on a thermostatically controlled warming table to maintain body temperature at 37°C. After a cannula was placed in the trachea, the rats were ventilated to maintain a PCO2 of 35-40 mmHg. The femoral artery was cannulated and MAP was directly recorded after a 30-min equilibration period. In the first series of experiments, we verified that blood pressures measured in ketamine- and Inactin-anesthetized Dahl S rats were comparable to those measured in the same rats when conscious. After blood pressure was measured, the kidneys were collected, and the degree of tubulointerstitial damage in the outer medulla and glomerular damage were assessed as described above.
Statistics
Mean values ± SE are presented. The significance of differences in mean values measured in control and anti-TGF-
Ab-treated groups was analyzed using an unpaired t-test or
an analysis of variance for repeated measures followed by the Duncan's
multiple-range test. A P value <0.05 was considered
statistically significant.
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RESULTS |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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Effect of Anti-TGF- Ab Therapy on Blood Pressure and Proteinuria
in Conscious Dahl S Rats
Ab treatment on the development
of hypertension in 9-wk-old male Dahl S rats fed a high-salt diet for 3 wk is presented in Fig. 1. There was no
significant difference in blood pressure measured in the rats given the
low and the high doses of anti-TGF- Ab; therefore, the data from these two groups were combined. MAP averaged 190 ± 4 mmHg
in control Dahl S rats (n = 12) fed a high-salt
diet for 3 wk. MAP was significantly lower in Dahl S rats treated with
the anti-TGF- Ab (177 ± 3 mmHg, n = 17).
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The effect of anti-TGF- Ab treatment on the excretion of protein in
Dahl S rats is presented in Table 1.
Proteinuria fell from 226 ± 20 to 154 ± 16 mg/day in the
Dahl S rats treated with the anti-TGF- Ab. Despite the reduction in
the urinary excretion of protein, indexes of glomerular injury such as
the plasma creatinine concentration were not significantly different
and averaged 0.9 ± 0.2 mg/dl in the control rats and 1.3 ± 0.2 mg/dl in the rats treated with the anti-TGF- Ab (Table 1). Both
values are elevated compared with a normal value of 0.52 ± 0.06 mg/dl measured in a group of normotensive, salt-resistant Brown Norway
rats (n = 16) fed the same diet for 3 wk. Creatinine
clearances were not significantly different and averaged 0.40 ± 0.09 ml · min
1 · g kidney
wt1 in the control Dahl S rats and 0.35 ± 0.07 ml · min1 · g kidney wt1 in
the rats treated with the anti-TGF- Ab (Table 1).
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Effect of Anti-TGF- Ab Therapy on Renal Hemodynamics in
Anesthetized Dahl S Rats
Ab treatment on renal hemodynamics is
presented in Table 2. RBF was not
significantly different in the control (3.13 ± 0.67 ml · min1 · g kidney wt1)
and anti-TGF- Ab-treated rats (3.22 ± 0.41 ml · min1 · g kidney wt1)
(Table 2). There was also no difference in the laser-Doppler cortical
blood flow (CBF) signal measured in the control rats (2.26 ± 0.19 V) and anti-TGF- Ab-treated rats (1.85 ± 0.23 V). On the other
hand, the medullary blood flow (MBF) signal was threefold greater in
anti-TGF- Ab-treated rats (0.99 ± 0.12 V) than in the control
rats (0.39 ± 0.09 V). The failure to detect a change in cortical
or kidney blood flow despite a large increase in MBF is not surprising
given that blood flow to the inner medulla only represents a small
fraction of the flow to the kidney (<1%).
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The Effect of Anti-TGF- Ab on Renal Pathology in Dahl S Rats
Ab-treated (1.76 ± 0.06 g) rats, indicating
that the degree of renal hypertrophy was similar in the two groups
(Table 1). The effect of blocking the effects of TGF- on glomerular morphology is illustrated by the representative PAS-stained kidney sections presented in Fig. 2,
A and B. Histological examination of glomeruli
from the control Dahl S rats (Fig. 2A) and anti-TGF- Ab-treated Dahl S rats (Fig. 2B) indicated that there was
marked expansion of the mesangial matrix in nearly every glomerulus
examined. A large percentage of glomerular capillaries was filled with
matrix material and there was PAS-positive material in most of the
injured glomeruli. Treating Dahl S rats with the anti-TGF- Ab had no effect on mean glomerular diameter (123.3 ± 1.4 µm;
n = 140 glomeruli, 7 rats) vs. control rats (121.2 ± 2.3 µm; n = 176 glomeruli, 8 rats). Chronic
treatment of rats with the anti-TGF- Ab also had no significant
effect on the degree of glomerular injury. Focal glomerulosclerosis
scores averaged 2.5 ± 0.11 (n = 140 glomeruli, 7 rats) (63% damage) in the control rats vs. 2.8 ± 0.18 (n = 176 glomerlui, 8 rats) (70% damage) in the rats
treated with the anti-TGF- Ab therapy. We also examined the degree
of sclerosis seen in a group of normotensive Dahl S rats maintained on
a low-salt diet throughout the study (0.4% NaCl). The glomerular
injury score (2.5 ± 0.06; n = 188 glomeruli, 8 rats) observed in these rats was not significantly different from that
seen in Dahl S rats fed the high-salt diet. These results are
consistent with previous reports that Dahl S rats exhibit a high degree
of glomerular damage even when maintained on a low-salt diet to
minimize the development of hypertension (35).
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A comparison of the appearance of the outer medulla of the kidney of
control (Fig. 2C) and anti-TGF- Ab-treated rats (Fig. 2D) is presented in Fig. 2. In the untreated Dahl S rats,
there is increased deposition of connective tissue in the vasa recta bundles, necrosis of the thick ascending limbs, and the formation of
protein casts in the outer medulla (Fig. 2C). In the
anti-TGF- Ab-treated Dahl S rats (Fig. 2D), the number of
patent vasa recta capillaries was significantly increased compared with
levels seen in the control Dahl S rats and the degree of necrosis of
thick ascending limbs and formation of protein casts in the outer
medulla was markedly reduced.
Immunohistochemical staining for -smooth muscle actin, a marker for
myofibroblasts associated with pathologic fibrosis (28), was observed in Bowman's capsule, tubular epithelial cells, mesangial cells, and the renal cortical interstitium in control Dahl S rats (Fig.
3A). Heavy positive staining
for smooth muscle actin also was observed in the interstitium and vasa
recta vascular bundles in the outer medulla of these animals (Fig.
3C). Rats treated with anti-TGF- Ab exhibited
substantially less staining for -smooth muscle actin in cortical and
medullary regions of the kidney (Fig. 3, B and
D). Nearly all of the staining was restricted to the wall of
renal arteries, which is consistent with the typical pattern of
staining for -smooth muscle actin seen in normotensive strains of
rats.
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A comparison of the levels of TGF-1 and TGF-2 mRNA expressed in
the kidneys of control and anti-TGF- Ab-treated rats is presented in
Fig. 4. The expression of TGF-1 and
TGF-2 mRNA was markedly reduced in kidneys of Dahl S rats
treated with the anti-TGF- Ab. This finding is consistent with the
lower levels of mRNA encoding type III collagen and the extra domain A
(EDA)-containing variant of fibronectin seen in the kidney of
anti-TGF- Ab-treated rats compared with the levels seen in control
Dahl S rats (Fig. 5).
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The results of our immunohistochemistry studies indicate that there are
elevated levels of TGF-1 protein expressed in the glomeruli,
proximal tubules, and interstitial space of Dahl S rats fed a high-salt
diet (Fig. 6A). The intense
staining in the interstitial space around some glomeruli may be due to
the loss of integrity of the Bowman's space and accumulation of
filtrate into the interstitium. The anti-TGF- Ab treatment markedly
reduced the staining for TGF-1 protein in both the renal cortical
and medullary interstitium and in the glomerulus (Fig. 6B).
Similar results were obtained using anti-TGF-2 primary Ab.
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Protocol 2: Early Intervention With Anti-TGF- Ab
Proteinuria and microalbuminuria.
The effect of anti-TGF- Ab treatment on the excretion of protein
in Dahl S rats fed a high-salt diet is presented in Fig. 7A. Protein excretion averaged
<20 mg/day in the anti-TGF- Ab-treated and control Dahl S rats when
fed a low-salt (0.1% NaCl) diet. It gradually rose in both the control
and anti-TGF- Ab-treated rats during the first 2 wk of a high-salt
diet. By day 18 of the high-salt diet, severe proteinuria
was observed in both experimental groups; however, the degree of
proteinuria tended to be lower in the anti-TGF- Ab-treated group
than in the control group (74 ± 12 vs. 103 ± 17 mg/day).
After 3 wk on a high-salt diet, the severity of the proteinuria in Dahl
S rats was significantly reduced from 172 ± 20 mg/day in control
rats to 91 ± 20 mg/day in the anti-TGF- Ab-treated rats.
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Ab treatment on the urinary excretion of
albumin in Dahl S rats is presented in Fig. 7B. In both the
control and anti-TGF- Ab-treated rats, albumin excretion was <10
mg/day when the rats were fed a low-salt diet (0.1% NaCl). After 3 wk
on a high-salt diet, albumin excretion was significantly lower in Dahl
S rats treated with anti-TGF- Ab therapy (45 ± 8 mg/day) than
in control rats (85 ± 21 mg/day).
Histological evaluation of kidneys.
A comparison of renal injury scores in control and anti-TGF-
Ab-treated rats is presented in Fig. 8. A
large percentage of glomerular capillaries was filled with matrix
material and there was PAS-positive material in most of the severely
injured glomeruli. Chronic treatment of these younger Dahl S rats with
anti-TGF- Ab significantly reduced the degree of glomerular injury.
The glomerular injury scores averaged 3.25 ± 0.06 in Dahl S rats
treated with the control Ab (n = 144 glomeruli, 7 rats)
vs. 2.73 ± 0.04 (n = 382 glomeruli, 15 rats) in
the anti-TGF- Ab-treated Dahl S rats (Fig. 8A) and
2.46 ± 0.05 (n = 122 glomeruli, 6 rats) in Dahl S
rats maintained on a low-salt diet throughout the study to prevent
hypertension.
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Ab therapy also reduced the degree of fibrosis of vasa
recta capillaries, necrosis of the thick ascending loop of Henle, and
the formation of protein casts in the outer medulla. In this regard,
22.2 ± 1.3% of the area in the outer medulla was occupied by
protein casts in control rats compared with only 5.6 ± 0.3% of
the outer medulla in rats treated with the anti-TGF- Ab (Fig.
8B). Dahl S rats maintained on a low-salt diet for life exhibited the same percentage of protein casts in the outer medulla (2.2 ± 0.3%) as was seen in the rats treated with the
anti-TGF- Ab.
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DISCUSSION |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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The present study examined the effects of chronic blockade of the
actions of TGF- with a murine monoclonal Ab (1D11) that neutralizes
all three of the isoforms of TGF- (1, 2, and 3) on the
development of hypertension, glomerulosclerosis, and/or tubulointerstitial renal disease in Dahl S rats fed a high-salt diet
for 3 wk. The results indicate that chronic treatment of Dahl S rats
with an anti-TGF- Ab significantly reduces blood pressure,
proteinuria, and albuminuria. The mechanism by which anti-TGF- Ab
therapy lowers blood pressure in Dahl S rats remains to be established;
however, we did find that there was marked fibrosis of the vasa recta
capillary bundles resulting in complete closure of most of the
capillaries in the outer medulla of Dahl S rats fed a high-salt diet.
This led to severe medullary ischemic injury, tubular necrosis,
and the formation of protein casts (Fig. 2). Chronic treatment of the
9-wk-old Dahl S rats with the anti-TGF- Ab reduced the deposition of
matrix in vasa recta bundles, preserved MBF, and reduced the degree of
tubular necrosis and the formation of protein casts in the outer
medulla. The beneficial effects of anti-TGF- Ab therapy were even
more apparent when we studied the effects of the anti-TGF- Ab
treatment in younger (6 wk of age) Dahl S rats that had less
preexisting renal damage. In this group, we found that the area
occupied by protein casts was fourfold greater in the outer medulla of
the control Dahl S rats than seen in the anti-TGF- Ab-treated rats.
Consistent with these histological findings, we found that MBF measured
using laser-Doppler flowmetry was threefold higher in Dahl S rats
treated with the anti-TGF- Ab than in control rats. These results
are consistent with the recent finding that chronic administration of
TGF- to normotensive Sprague-Dawley rats reduces MBF and that this
is associated with marked fibrosis of vasa recta capillaries and
tubular necrosis in the outer medulla of the kidney (16).
Collectively, these findings suggest that the fall in creatinine
clearance observed in Dahl S rats fed a high-salt diet may involve
fibrosis of vasa recta capillaries, medullary hypoperfusion, hypoxic
injury to the thick ascending limb, acute tubular necrosis, the
formation of protein casts, and tubular obstruction. Furthermore, our
results suggest that chronic treatment of rats with an anti-TGF- Ab
may improve renal function by ameliorating the pathological changes that occur in the outer medulla.
The preservation of MBF may also contribute to the antihypertensive
effect of the anti-TGF- Ab therapy observed in Dahl S rats. In
previous studies, we reported that sodium reabsorption in the thick
ascending limb is markedly elevated in Dahl S rats (13,
42) and this leads to volume expansion that accounts for the
initial rise in blood pressure when Dahl S rats are fed a high-salt
diet (10). However, with time, MBF falls in Dahl S rats
and this contributes to a further blunting of the pressure-natriuresis relationship (4, 31) and an increase in the severity of
the hypertension. Other investigators have reported that chronic renal interstitial infusion of L-arginine to elevate the
production of nitric oxide prevents the fall in MBF and attenuates the
development of hypertension in Dahl S rats (22, 23).
Moreover, reductions in MBF have been linked to the resetting of the
pressure-natriuresis relationship and the development of hypertension
in many other models of hypertension, including the spontaneously
hypertensive rat (4, 14, 32) and
NG-nitro-L-arginine methyl ester
(21) and vasopressin-induced hypertension (25,
27).
On the other hand, numerous investigators have shown that TGF-1
alters the expression of endothelial nitric oxide synthase and
COX-2 and components of the renin-angiotensin system, vascular smooth
muscle, and other tissues. Thus it is just as likely that the
antihypertensive effect of TGF- therapy in Dahl S rats may be due to
blockade of the actions of TGF- on the expression of these paracrine
factors that regulate vascular tone (8, 12). Thus further
work is needed to sort out the relative contributions of changes in
renal and vascular function to the fall in blood pressure after
anti-TGF- Ab therapy.
In addition to its effect on blood pressure, we found that treating
Dahl S rats with anti-TGF- Ab therapy reduced protein excretion in
Dahl S rats fed a high-salt diet. However, no improvement in the degree
of glomerular injury at the light microscopic level was observed in the
kidneys of 9-wk-old Dahl S rats chronically treated with the
anti-TGF- Ab. This was an unexpected finding, because the
anti-TGF- Ab therapy greatly reduced expression on the TGF-1 and
TGF-2 mRNA and protein in the glomerulus and renal interstitium of
these rats. There is a large body of evidence correlating changes in
TGF- expression in the glomerulus with the degree of extracellular
matrix expansion in the glomerulus of diabetic rats (33),
normotensive rats (38), transgenic mice that overexpress
TGF- (18), and Dahl S rats (36). We therefore postulated that, although blockade of TGF- probably attenuated the hypertension-induced glomerular damage, the treatment could not reverse the high degree of preexisting glomerulosclerosis seen in the kidneys of Dahl S rats maintained on a low-salt diet. To
test this hypothesis, we studied the effect of anti-TGF- Ab therapy
in young (6 wk old) Dahl S rats that have less preexisting glomerular
injury. After 3 wk on a high-salt diet, the control 6-wk-old Dahl S
rats exhibited the same degree of glomerular injury as was seen in the
9-wk-old rats. However, the degree of glomerulosclerosis in the
anti-TGF- Ab-treated group was significantly reduced and not
different from the degree of injury seen in age-matched nonhypertensive Dahl S rats maintained on a low-salt diet (0.1% NaCl).
The mechanism by which chronic treatment of Dahl S rats reduces the
expression of TGF- mRNA and protein in the kidney remains to be
determined. This may simply reflect the fact that TGF- production is
upregulated in damaged glomeruli and ischemic tubular cells in
Dahl S rats and treatment of the animals with the antibody lowers
TGF- production by reducing the degree of hypertension-induced renal
injury. Alternatively, TGF- is known to induce expression of growth
factors and components of the renin-angiotensin system that in turn
increase the production of TGF- (37). By neutralizing the actions of TGF-, the antibody may interrupt this
positive-feedback loop.
An important question that remains to be answered is how does
anti-TGF- Ab therapy reduce proteinuria in 9- to 12-wk-old Dahl S
rats without altering the degree of glomerular damage? One possibility
is that TGF- may directly affect the permeability properties of the
glomerulus to proteins or alter glomerular hemodynamics. In this
regard, Sharma et al. (34) recently demonstrated that TGF- can directly increase the permeability of isolated glomeruli to
albumin and this may contribute to proteinuria in vivo.
In summary, chronic administration of anti-TGF- Ab lowered blood
pressure and decreased urinary excretion of protein and albumin in Dahl
S rats fed a high-salt diet for 3 wk. Anti-TGF- Ab therapy did not
alter total RBF or CBF in Dahl S rats. However, MBF was significantly
higher in Dahl S rats treated with the anti-TGF- Ab. This
observation, coupled with histological evidence of reduced fibrosis of
the vasa recta bundles and tubular necrosis in the outer medulla of the
kidney, suggests that the renoprotective effects of anti-TGF- Ab
therapy may involve changes in renal medullary hemodynamics and/or
changes in the permeability of glomerular capillaries to albumin.
Overall, these findings indicate that anti-TGF- Ab treatment may
have therapeutic potential in reducing proteinuria and renal injury
associated with salt-sensitive hypertension and perhaps diabetes.
| |
ACKNOWLEDGEMENTS |
|---|
The authors thank C. A. Bobrowitz and G. Slocum for help in histology and J. G. Dickhout for help with protein cast determination.
| |
FOOTNOTES |
|---|
This work was supported in part by NIH Grants HL-29587 and HL-36279 and research funds provided by Genzyme, Framingham, MA.
Address for reprint requests and other correspondence: R. J. Roman, Medical College of Wisconsin, Dept. of Physiology, 8701 Watertown Plank Rd., Milwaukee, WI 53226 (E-mail: rroman{at}mcw.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.
May 16, 2002;10.1152/ajpregu.00098.2002
Received 19 February 2002; accepted in final form 11 May 2002.
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REFERENCES |
|---|
|
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
1.
Border, WA,
and
Noble NA.
Transforming growth factor- in tissue fibrosis.
N Engl J Med
331:
1286-1292,
1994
2.
Bottinger, EP,
Letterio JJ,
and
Roberts AB.
Biology of TGF- in knockout and transgenic mouse models.
Kidney Int
51:
1355-1360,
1997[Web of Science][Medline].
3.
Chen, PY,
St John PL,
Kirk KA,
Abrahamson DR,
and
Sanders PW.
Hypertensive nephlerosclerosis in the Dahl/Rapp rat. Initial sites of injury and effect of dietary L-arginine supplementation.
Lab Invest
68:
174-184,
1993[Web of Science][Medline].
4.
Cowley, AW, Jr,
Mattson DL,
Lu S,
and
Roman RJ.
The renal medulla and hypertension.
Hypertension
25:
663-673,
1995
5.
Dasch, JR,
Pace DR,
Waegell W,
Inenaga D,
and
Ellingsworth L.
Monoclonal antibodies recognizing transforming growth factor-. Bioactivity neutralization and transforming growth factor beta 2 affinity purification.
J Immunol
142:
1536-1541,
1989[Abstract].
6.
Derynck, R,
Jarrett JA,
Chen EY,
Eaton DH,
Bell JR,
Assoian RK,
Roberts AB,
Sporn MB,
and
Goeddel DV.
Human transforming growth factor-beta complementary DNA sequence and expression in normal and transformed cells.
Nature
316:
701-705,
1985[Medline].
7.
Douthwaite, JA,
Johnson TS,
Haylor JL,
Watson P,
and
El Nahas AM.
Effects of transforming growth factor-beta1 on renal extracellular matrix components and their regulating proteins.
J Am Soc Nephrol
10:
2109-2119,
1999
8.
Fong, CY,
Pang L,
Holland E,
and
Knox AJ.
TGF-b1 stimulates IL-8 release, COX-2 expression, and PGE2 release in human airway smooth muscle cells.
Am J Physiol Lung Cell Mol Physiol
279:
L201-L207,
2000
9.
Glumoff, V,
Savontaus M,
Vehanen J,
and
Vuorio E.
Analysis of aggrecan and tenascin gene expression in mouse skeletal tissues by northern and in situ hybridization using species specific cDNA probes.
Biochim Biophys Acta
1219:
613-622,
1994[Medline].
10.
Greene, AS,
Yu ZY,
Roman RJ,
and
Cowley AW, Jr.
Role of blood volume expansion in Dahl rat model of hypertension.
Am J Physiol Heart Circ Physiol
258:
H508-H514,
1990
11.
Han, DC,
Hoffman BB,
Hong SW,
Guo J,
and
Ziyadeh F.
Therapy with antisense TGF-1 oligodeoxynucleotides reduces kidney weight and matrix mRNAs in diabetic mice.
Am J Physiol Renal Physiol
278:
F628-F634,
2000
12.
Inoue, N,
Venema RC,
Sayegh HS,
Ohara Y,
Murphy TJ,
and
Harrison DG.
Molecular regulation of the bovine endothelial cell nitric oxide synthase by transforming growth factor-1.
Arterioscler Thromb Vasc Biol
15:
1255-1261,
1995
13.
Ito, O,
and
Roman RJ.
Role of 20-HETE in elevating chloride transport in the thick ascending limb of Dahl SS/Jr rats.
Hypertension
33:
419-423,
1999
14.
Johnson, RJ,
and
Schreiner GF.
Hypothesis: the role of acquired tubulointerstitial disease in the pathogenesis of salt-dependent hypertension.
Kidney Int
52:
1169-1179,
1997[Web of Science][Medline].
15.
Krag, S,
Osterby R,
Chai Q,
Nielsen CB,
and
Wogensen L.
TGF-1-induced glomerular disorder in associated with impaired concentrating ability mimicking primary glomerular disease with renal failure in man.
Lab Invest
80:
1855-1868,
2000[Web of Science][Medline].
16.
Kelly, FJ,
Anderson S,
Thompson MM,
Oyama TT,
Kennefick TM,
Corless CL,
Roman RJ,
Kurtzberg L,
Pratt BM,
and
Ledbetter SR.
Acute and chronic renal effects of recombinant human TGF- in the rat.
J Am Soc Nephrol
10:
1264-1273,
1999
17.
Ketteler, M,
Noble NA,
and
Border WA.
Increased expression of transforming growth factor-beta in renal disease.
Curr Opin Nephrol Hypertens
3:
446-452,
1994[Medline].
18.
Kopp, JB,
Factor VM,
Mozes M,
Nagy P,
Sanderson N,
Bottinger E,
Klotman PE,
and
Thorgeirsson SS.
Transgenic mice with increased plasma levels of TGF-1 develop progressive renal disease.
Lab Invest
74:
991-1003,
1996[Web of Science][Medline].
19.
Li, B,
Khanna A,
Sharma V,
Singh T,
Suthanthiran M,
and
August P.
TGF-1 DNA polymorphisms, protein levels, and blood pressure.
Hypertension
33:
271-275,
1999
20.
Madisen, L,
Webb NR,
Rose TM,
Marquardt H,
Ikeda T,
Twardzik D,
Seyedin S,
and
Purchio AF.
Transforming growth factor-beta 2: cDNA cloning and sequence analysis.
DNA (NY)
7:
1-8,
1998.
21.
Mattson, DL,
Lu S,
and
Cowley Jr AW.
Role of nitric oxide in the control of the renal medullary circulation.
Clin Exp Pharmacol Physiol
24:
587-590,
1997[Web of Science][Medline].
22.
Miyata, N,
Zou AP,
Mattson DL,
and
Cowley Jr A
W. Renal medullary interstitial infusion of L-arginine prevents hypertension in Dahl salt-sensitive rats.
Am J Physiol Regul Integr Comp Physiol
275:
R1667-R1673,
1998
23.
Miyata, N,
and
Cowley Jr AW.
Renal intramedullary infusion of L-arginine prevents reduction of medullary blood flow and hypertension in Dahl salt-sensitive rats.
Hypertension
33:
446-450,
1999
24.
Mozes, MM,
Bottinger EP,
Jacot TA,
and
Kopp JB.
Renal expression of fibrotic matrix proteins and of transforming growth factor-beta (TGF-beta) isoforms in TGF-beta transgenic mice.
J Am Soc Nephrol
10:
271-280,
1999
25.
Nakanishi, K,
Mattson DL,
Gross V,
Roman RJ,
and
Cowley Jr AW.
Control of renal medullary blood flow by vasopressin V1 and V2 receptors.
Am J Physiol Regul Integr Comp Physiol
269:
R193-R200,
1995
26.
Odermatt, E,
Tamkun JW,
and
Hynes RO.
Repeating modular structure of the fibronectin gene: relationship to protein structure and subunit variation.
Proc Natl Acad Sci USA
82:
6571-6575,
1985
27.
Park, F,
Mattson DL,
Skelton MM,
and
Cowley Jr AW.
Localization of the vasopressin V1a and V2 receptors within the renal cortical and medullary circulation.
Am J Physiol Regul Integr Comp Physiol
273:
R243-R251,
1997
28.
Powell, DW,
Mifflin RC,
Valentich JD,
Crowe SE,
Saada JI,
and
West AB.
Myofibroblasts I. Paracrine cells important in health and disease.
Am J Physiol Cell Physiol
277:
C1-C19,
1999
29.
Rapp, JP.
Dahl salt-sensitive and salt-resistant rats.
Hypertension
4:
753-763,
1982
30.
Raij, L,
Chiou XC,
Owens R,
and
Wrigley B.
Therapeutic implications of hypertension-induced glomerular injury. Comparison of enalapril and a combination of hydralazine, reserpine, and hydrochlorothiazide in an experimental model.
Am J Med
79:
37-41,
1985[Web of Science][Medline].
31.
Roman, RJ,
and
Kaldunski M.
Pressure-natriuresis and cortical and papillary blood flow in inbred Dahl rats.
Am J Physiol Regul Integr Comp Physiol
261:
R595-R600,
1991
32.
Roman, RJ,
Alonso-Galicia M,
and
Wilson TW.
Renal P450 metabolites of arachidonic acid and the development of hypertension in Dahl salt-sensitive rats.
Am J Hypertens
10:
63S-67S,
1997[Medline].
33.
Sharma, K,
and
Ziyadeh F.
Renal hypertrophy is associated with upregulation of TGF-1 gene expression in diabetic BB rat and NOD mouse.
Am J Physiol Renal Fluid Electrolyte Physiol
267:
F1094-F1101,
1994
34.
Sharma, R,
Khanna A,
Sharma M,
and
Savin VJ.
Transforming growth factor-beta 1 increases albumin permeability of isolated rat glomeruli via hydroxyl radicals.
Kidney Int
58:
131-136,
2000[Web of Science][Medline].
35.
Sterzel, RB,
Luft FC,
Gao Y,
Schnermann J,
Briggs JP,
Ganten D,
Waldherr R,
Schnabel E,
and
Kriz W.
Renal disease and the development of hypertension in salt-sensitive Dahl rats.
Kidney Int
33:
1119-1129,
1988[Web of Science][Medline].
36.
Tamaki, K,
Okuda S,
Nakayama M,
Yanagida T,
and
Fujishima M.
Transforming growth factor 1 in hypertensive renal injury in Dahl salt-sensitive rats.
J Am Soc Nephrol
7:
2578-2589,
1996[Abstract].
37.
Wu, LL,
Cox A,
Roe CJ,
Dziadek M,
Cooper ME,
and
Gilbert RE.
Transforming growth factor beta 1 and renal injury following subtotal nephrectomy in the rat: role of the renin-angiotensin system.
Kidney Int
51:
1553-1567,
1997[Web of Science][Medline].
38.
Yamamoto, T,
Noble NA,
Miller DE,
and
Border WA.
Sustained expression of TGF-1 underlies development of progressive kidney fibrosis.
Kidney Int
45:
916-927,
1994[Web of Science][Medline].
39.
Ying, WZ,
and
Sanders PW.
Dietary salt modulates renal production of transforming growth factor- in rats.
Am J Physiol Renal Physiol
274:
F635-F641,
1998
40.
Yu, HC,
Burrell LM,
Black MJ,
Wu LL,
Dilley DJ,
Cooper ME,
and
Johnston CI.
Salt induces myocardial and renal fibrosis in normotensive and hypertensive rats.
Circulation
98:
2621-2628,
1998
41.
Ziyadeh, FN,
Hoffman BB,
Han DC,
Cruz MC,
Iglesias-De La Cruz MA,
Hong SW,
Isono M,
Chen S,
McGowan TA,
and
Sharma K.
Long-term prevention of renal insufficiency, excess matrix gene expression, and glomerular mesangial matrix by treatment with monocolonal antitransforming growth factor- antibody in db/db diabetic mice.
Proc Natl Acad Sci USA
97:
8015-8020,
2000
42.
Zou, AP,
Drummond HA,
and
Roman RJ.
Role of 20-HETE in elevating loop chloride reabsorption in Dahl SS/Jr rats.
Hypertension
27:
631-635,
1996
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