17beta-Estradiol attenuates diabetic kidney disease by regulating extracellular matrix and transforming growth factor-beta protein expression and signaling

Non-proteinuric pathways in loss of renal function in patients with type 2 diabetes

Largely on the basis of data from patients with type 1 diabetes, the natural history of diabetic renal disease has been classified as a sequence of three stages: normoalbuminuria, microalbuminuria, and macroalbuminuria. Progressive decline of glomerular filtration rate (GFR) was thought to parallel the onset of macroalbuminuria (overt nephropathy), whereas glomerular hyperfiltration was deemed a hallmark of early disease. However, researchers have since shown that albuminuria is a continuum and that GFR can start to decline before progression to overt nephropathy. In addition to proteinuria, other risk factors might contribute to GFR deterioration including female sex, obesity, dyslipidaemia (in particular hypertriglyceridaemia), hypertension, and glomerular hyperfiltration, at least in a subgroup of patients. This phenomenon could explain why patients with type 2 diabetes can have renal insufficiency even before the onset of overt nephropathy, and might also suggest why the heterogeneous phenotype of type 2 diabetic renal disease does not necessarily associate with typical histological lesions of diabetic renal disease, unlike in type 1 diabetic renal disease. Patients with renal insufficiency but without albuminuria are usually excluded from randomised clinical trials in overt nephropathy, thus optimum treatment for this group of patients is unknown. The wide inter-patient variability of the disease probably needs individually tailored intervention.

17β Estradiol Modulates Perfusion Pressure and Expression of 5-LOX and CYP450 4A in the Isolated Kidney of Metabolic Syndrome Female Rats

Prevalence of metabolic syndrome and progression of nephropathy depend on sex. We examined a protective effect of estradiol against nephropathy in metabolic syndrome through the modulation of the arachidonic acid metabolism by activating the 5-lipoxygenase and cytochrome p450 4A pathways. 28 female Wistar rats were divided into four groups of seven animals each: control, intact metabolic syndrome, ovariectomized metabolic syndrome, and metabolic syndrome ovariectomized plus estradiol. Blood pressure, body weight, body fat, triglycerides, insulin, HOMA-index, albuminuria, and TNF-α were increased in ovariectomized metabolic syndrome rats (p < 0.001). The perfusion pressure in isolated kidneys of ovariectomized metabolic syndrome rats in presence of 4 μg of arachidonic acid was increased. The inhibitors of the arachidonic acid metabolism Baicalein, Miconazole, and Indomethacin in these rats decreased the perfusion pressure by 57.62%, 99.83%, and 108.5%, respectively and they decreased creatinine clearance and the arachidonic acid percentage. Phospholipase A2 expression in the kidney of ovariectomized metabolic syndrome rats was not modified. 5-lipoxygenase was increased in metabolic syndrome ovariectomized rats while cytochrome p450 4A was decreased. In conclusion, the loss of estradiol increases renal damage while the treatment with estradiol benefits renal function by modulating arachidonic acid metabolism through the 5-lipoxygenase and cytochrome p450 4A pathways.

Progesterone ameliorates diabetic nephropathy in streptozotocin-induced diabetic Rats

BACKGROUND

Previous studies reported that 17β-estradiol may influence the progression of diabetic renal disease in females. The present study was intended to provide an insight into the specific effects of progesterone, the other female sex hormone, in the diabetic renal complications.

METHODS

Adult female wistar rats were divided into four groups (n = 6/group): intact control (non-diabetic, ND), intact diabetic (D), ovariectomized diabetic (D-OVX) and ovariectomized diabetic which were treated with progesterone (D-OVX + P; 10 mg/kg, s.c, every second day) for 10 weeks. Diabetes was induced by a single dose injection of 55 mg/kg streptozotocin. Expressions of transforming growth factor-β (TGF-β), fibronectin, vascular endothelial growth factor-A (VEGF-A), angiotensin II type 1 receptor (ATR1) and podocyte markers (nephrin and podocin) were assessed by immunohistochemistry and real-time PCR.

RESULTS

The treatment of D-OVX rats with progesterone attenuated diabetic-associated increases in the urinary albumin to creatinine ratio, glomerulosclerosi and the expression of profibrotic and angiogenic factors (TGF-β, Fibronectin and VEGF-A). Furthermore, progesterone supplementation prevented diabetes-induced downregulation of nephrin and podocin while the overexpression of ATR1 in the diabetic rats was inhibited by the progesterone supplementation.

CONCLUSION

These results provided evidence, for the first time, that the replacement of progesterone can ameliorate the renal damage in the experimental models of diabetic nephropathy through improving the renal function; the inhibition of renal fibrosis and abnormal angiogenesis; along with the amelioration of podocyte injury. Additionally, the blocking of renin-angiotensin system through the down-regulation of ATR1 expression may also account for the reno-protective effect of progesterone.

Endogenous female sex hormones delay the development of renal dysfunction in apolipoprotein E-deficient mice

Background

Hypercholesterolemia is a well-established risk factor for the development of kidney injury. Considering that female sex hormones may play a preventative role in both cardiovascular and renal diseases, the aim of the present study was to evaluate the effects of female sex hormones on hypercholesterolemia-induced renal dysfunction.

Methods

Apolipoprotein E-deficient (ApoE) and C57 control female mice underwent an ovariectomy (OVX) or sham surgery and after 2 months, creatinine clearance, uremia and proteinuria were determined. Renal oxidative stress and lipid deposition were also quantified. Values are presented as mean ± SEM. Statistical analyses were performed using Two-way ANOVA followed by Tukey’s post hoc test.

Results

Creatinine clearance (μL/min) was similar between C57 (171 ± 17) and ApoE (140 ± 26) mice underwent sham surgery. OVX resulted in a reduced glomerular filtration rate in both C57 (112 ± 8, ~ − 35%, p < 0.05) and ApoE (61 ± 10, ~ − 56%, p < 0.05) animals. Plasma levels of urea (mg/dL) were higher in both ApoE groups (Sham: 73 ± 7; OVX: 73 ± 8, p < 0.05) when compared to C57 animals (Sham: 49 ± 3; OVX: 60 ± 4), with no changes among ovariectomized groups. Proteinuria levels (mg/24 h) were similar between C57 (Sham: 25.1 ± 5.7; OVX: 33.7 ± 4.7) and ApoE sham animals (26.4 ± 3.5), however, 24-h urine protein excretion was augmented in ApoE OVX animals (49.6 ± 5.8, p < 0.05). Histological kidney analysis demonstrated that the absence of female sex hormones resulted in increased oxidative stress, which was more severe in ApoE mice (C57 Sham: 9.2 ± 0.4; C57 OVX: 22.9 ± 1.0; ApoE Sham: 13.9 ± 0.7; ApoE OVX: 34.0 ± 1.4 au x 10³, p < 0.05). As expected, ApoE mice presented higher lipid deposition, which was not affected by OVX (C57 Sham: 0 ± 0; C57 OVX: 0 ± 0; ApoE Sham: 6.8 ± 1.6; ApoE OVX: 5.2 ± 0.8% x 10⁻², p < 0.05). Ovariectomy resulted in a similar reduction in ER-α protein expression in the renal cortex (C57: 0.78 ± 0.04; ApoE: 0.81 ± 0.04 au, p < 0.05) when compared to sham animals (C57:1.00 ± 0.04; ApoE: 1.03 ± 0.03 au).

Conclusion

Taken together these data indicate that female sex hormones may delay hypercholesterolemia-induced renal dysfunction and emphasizes the importance of plasma cholesterol control in post-menopausal women.

Myocardin-Related Transcription Factor A Epigenetically Regulates Renal Fibrosis in Diabetic Nephropathy

Diabetic nephropathy (DN) is one of the most common complications associated with diabetes and characterized by renal microvascular injury along with accelerated synthesis of extracellular matrix proteins causing tubulointerstitial fibrosis. Production of type I collagen, the major component of extracellular matrix, is augmented during renal fibrosis after chronic exposure to hyperglycemia. However, the transcriptional modulator responsible for the epigenetic manipulation leading to induction of type I collagen genes is not clearly defined. We show here that tubulointerstitial fibrosis as a result of DN was diminished in myocardin-related transcription factor A (MRTF-A) -deficient mice. In cultured renal tubular epithelial cells and the kidneys of mice with DN, MRTF-A was induced by glucose and synergized with glucose to activate collagen transcription. Notably, MRTF-A silencing led to the disappearance of prominent histone modifications indicative of transcriptional activation, including acetylated histone H3K18/K27 and trimethylated histone H3K4. Detailed analysis revealed that MRTF-A recruited p300, a histone acetyltransferase, and WD repeat-containing protein 5 (WDR5), a key component of the histone H3K4 methyltransferase complex, to the collagen promoters and engaged these proteins in transcriptional activation. Estradiol suppressed collagen production by dampening the expression and binding activity of MRTF-A and interfering with the interaction between p300 and WDR5 in renal epithelial cells. Therefore, targeting the MRTF-A-associated epigenetic machinery might yield interventional strategies against DN-associated renal fibrosis.

Role of G protein-coupled estrogen receptor 1 in modulating transforming growth factor-β stimulated mesangial cell extracellular matrix synthesis and migration

Estrogen has been demonstrated to exert beneficial effects on kidney; however, the role of G protein-coupled estrogen receptor 1 (GPER) is still uncertain. In the present study, we investigated the effect of 17β-estradiol and GPER agonist Fulvestrant on extracellular matrix production under transforming growth factor-β1 (TGF-β1) stimulation in human and rat mesangial cells. As a result, 17β-estradiol and Fulvestrant inhibit TGF-β1-induced type IV collagen and fibronectin expression in a dose-dependent manner, by suppressing acute Smad2/3 phosphorylation and Smad4 complex formation. Furthermore, estrogen and Fulvestrant also down-regulate Smad signaling by promoting ubiquitin/proteasome-dependent Smad2 degradation. These effects could be abrogated by receptor antagonist G-15 or GPER gene knockdown. GPER is also required for estrogen and Fulvestrant to regulate mesangial cell migration in response to TGF-β1. To conclude, GPER is crucial in modulating glomerular mesangial cell function including extracellular matrix production and migration.

Klotho attenuates high glucose-induced fibronectin and cell hypertrophy via the ERK1/2-p38 kinase signaling pathway in renal interstitial fibroblasts

Although exogenous klotho attenuates renal fibrosis, it is not known if exogenous klotho attenuates diabetic nephropathy (DN). Thus, we studied the anti-fibrotic mechanisms of klotho in terms of transforming growth factor-β (TGF-β) and signaling pathways in high glucose (HG, 30 mM)-cultured renal interstitial fibroblast (NRK-49F) cells. We found that HG increased klotho mRNA and protein expression. HG also activated TGF-β Smad2/3 signaling and activated extracellular signal-regulated kinase (ERK1/2) and p38 kinase signaling. Exogenous klotho (400 pM) attenuated HG-induced TGF-β bioactivity, type II TGF-β receptor (TGF-βRII) protein expression and TGF-β Smad2/3 signaling. Klotho also attenuated HG-activated ERK1/2 and p38 kinase. Additionally, klotho and inhibitors of ERK1/2 or p38 kinase attenuated HG-induced fibronectin and cell hypertrophy. Finally, renal tubular expression of klotho decreased in the streptozotin-diabetic rats at 8 weeks. Thus, exogenous klotho attenuates HG-induced profibrotic genes, TGF-β signaling and cell hypertrophy in NRK-49F cells. Moreover, klotho attenuates HG-induced fibronectin expression and cell hypertrophy via the ERK1/2 and p38 kinase-dependent pathways.

Tubulointerstitial disease in diabetic nephropathy

Diabetes mellitus is the major cause of end stage renal disease (ESRD). We cannot predict which patient will be affected. ESRD patients suffer an extremely high mortality rate, due to a very high incidence of cardiovascular disease. Several randomized, prospective studies have been conducted to quantify the impact of strict glycemic control on morbidity and mortality, and have consistently demonstrated an association between strict glycemic control and a reduction in ESRD. Within the past 20 years, despite the implementation of treatments that were presumed to be renoprotective, diabetes mellitus has continued to rank as the leading cause of ESRD, which clearly indicates that we are still far from understanding the mechanisms involved in the initiation of ESRD. Progressive albuminuria has been considered as the sine qua non of diabetic nephropathy, but we know now that progression to diabetic nephropathy may well happen in the absence of initial microalbuminuria. The search for new biomarkers of early kidney damage has received increasing interest, since early identification of the pathways leading to kidney damage may allow us to adopt measures to prevent the development of ESRD. Most of these biomarkers are deeply influenced by environment, genetics, sex differences, and so on, making it extremely difficult to identify the ideal biomarker to target. At present, there are no new drugs that come close to providing the solutions we desire for our patients (ie, reducing complications). Even when used in combination with standard care, renal complications are, at best, only modestly reduced, at the considerable expense of additional pill burden and exposure to serious off-target effects. In this review, some of the hypothesized mechanisms of this heterogeneous disease will be considered, with particular attention to the tubule–interstitial compartment.

Classical estrogen receptors and ERα splice variants in the mouse

Estrogens exert a variety of effects in both reproductive and non-reproductive tissues. With the discovery of ERα splice variants, prior assumptions concerning tissue-specific estrogen signaling need to be re-evaluated. Accordingly, we sought to determine the expression of the classical estrogen receptors and ERα splice variants across reproductive and non-reproductive tissues of male and female mice. Western blotting revealed that the full-length ERα66 was mainly present in female reproductive tissues but was also found in non-reproductive tissues at lower levels. ERα46 was most highly expressed in the heart of both sexes. ERα36 was highly expressed in the kidneys and liver of female mice but not in the kidneys of males. ERβ was most abundant in non-reproductive tissues and in the ovaries. Because the kidney has been reported to be the most estrogenic non-reproductive organ, we sought to elucidate ER renal expression and localization. Immunofluorescence studies revealed ERα66 in the vasculature and the glomerulus. It was also found in the brush border of the proximal tubule and in the cortical collecting duct of female mice. ERα36 was evident in mesangial cells and tubular epithelial cells of both sexes, as well as podocytes of females but not males. ERβ was found primarily in the podocytes in female mice but was also present in the mesangial cells in both sexes. Within the renal cortex, ERα46 and ERα36 were mainly located in the membrane fraction although they were also present in the cytosolic fraction. Given the variability of expression patterns demonstrated herein, identification of the specific estrogen receptors expressed in a tissue is necessary for interpreting estrogenic effects. As this study revealed expression of the ERα splice variants at multiple sites within the kidney, further studies are warranted in order to elucidate the contribution of these receptors to renal estrogen responsiveness.

The Process and Development Mechanism of Age-related Fibrosis in the Pancreatic Islets of Sprague-Dawley Rats: Immunohistochemical Detection of Myofibroblasts and Suppression Effect by Estrogen Treatment

The mechanism of spontaneous islet fibrosis in Sprague-Dawley rats was investigated. Using sections of the pancreas in naive males aged 26 to 102 weeks old and 26-week-old males injected with β-estradiol 3-benzoate (EB), the incidence of lesions and histological scores of fibrosis were examined in conjunction with immunohistochemistry for α-smooth muscle actin (α-SMA), platelet-derived growth factor receptor-α (PDGFRα) and estrogen receptor-α (ERα). The incidence of islet fibrosis increased in 78-week-old animals compared to the 26-week-old animals, and the incidence of atrophy in the fibrotic islet increased in animals over 52 weeks old. α-SMA and PDGFRα were positively stained mainly in fibrotic/inflammatory islets, and the histological score of α-SMA in the fibrotic islet decreased age-dependently. Notably, α-SMA and PDGFRα were co-expressed in inflammatory islets with a high score at all ages. The positive index of ERα in the EB-treated group increased when compared with that of the naive group. However, it was independent of the existence of fibrosis. In contrast, the score of α-SMA and PDGFRα decreased in the EB-treated group. In conclusion, it was clarified that a part of age-related fibrosis in islets became atrophy with age, and α-SMA-positive myofibroblasts were considered to contribute to the development of fibrosis. Strong PDGFRα stainability in fibrotic/inflammatory islets may imply that myofibroblasts were stimulated by PDGF to produce an extracellular matrix. Although estradiol has been known to suppress fibrosis/inflammation in the islet, nuclear-located ER-dependent signaling was considered not to be involved in the suppression mechanism. EB possibly affected the inhibition of the appearance of myofibroblasts.

Genetic variations in SMAD7 are associated with colorectal cancer risk in the colon cancer family registry

Background

Recent genome-wide studies identified a risk locus for colorectal cancer at 18q21, which maps to the SMAD7 gene. Our objective was to confirm the association between SMAD7 SNPs and colorectal cancer risk in the multi-center Colon Cancer Family Registry.

Materials and Methods

23 tagging SNPs in the SMAD7 gene were genotyped among 1,592 population-based and 253 clinic-based families. The SNP-colorectal cancer associations were assessed in multivariable conditional logistic regression.

Results

Among the population-based families, both SNPs rs12953717 (odds ratio, 1.29; 95% confidence interval, 1.12–1.49), and rs11874392 (odds ratio, 0.80; 95% confidence interval, 0.70–0.92) were associated with risk of colorectal cancer. These associations were similar among the population- and the clinic-based families, though they were significant only among the former. Marginally significant differences in the SNP-colorectal cancer associations were observed by use of nonsteroidal anti-inflammatory drugs, cigarette smoking, body mass index, and history of polyps.

Conclusions

SMAD7 SNPs were associated with colorectal cancer risk in the Colon Cancer Family Registry. There was evidence suggesting that the association between rs12953717 and colorectal cancer risk may be modified by factors such as smoking and use of nonsteroidal anti-inflammatory drugs.

Sugar, sex, and TGF-β in diabetic nephropathy

TGF-β is well known to play a critical role in diabetic kidney disease, and ongoing clinical studies are testing the potential therapeutic promise of inhibiting TGF-β production and action. An aspect of TGF-β action that has not received much attention is its potential role in explaining sex-related proclivity for kidney disease. In this review, we discuss recent studies linking TGF-β signaling to sex-related effects in diabetic kidney disease and suggest targets for future studies.

In vivo 17β-estradiol treatment contributes to podocyte actin stabilization in female db/db mice

We recently showed that 17β-estradiol (E(2)) treatment ameliorated type 2 diabetic glomerulosclerosis in mice in part by protecting podocyte structure and function. Progressive podocyte damage is characterized by foot process effacement, vacuolization, detachment of podocytes from the glomerular basement membrane, and apoptosis. In addition, podocytes are highly dependent on the preservation of their actin cytoskeleton to ensure proper function and survival. Because E(2) administration prevented podocyte damage in our study on diabetic db/db mice and has been shown to regulate both actin cytoskeleton and apoptosis in other cell types and tissues, we investigated whether actin remodeling and apoptosis were prevented in podocytes isolated from E(2)-treated diabetic db/db mice. We performed G-actin/F-actin assays, Western analysis for Hsp25 expression, Ras-related C(3) botulinum toxin substrate 1 (Rac1) activity, and apoptosis assays on previously characterized podocytes isolated from both in vivo-treated placebo and E(2) female db/db mice. We found that in vivo E(2) protects against a phenotype change in the cultured podocytes characterized by a percent increase of F-actin vs. G-actin, suppression of Hsp25 expression and transcriptional activation, increase of Rac1 activity, and decreased apoptotic intermediates. We conclude from these studies that E(2) treatment protects against podocyte damage and may prevent/reduce diabetes-induced kidney disease.

Gender and estradiol as major factors in the expression and dimerization of nNOSα in rats with experimental diabetic gastroparesis

BACKGROUND

The molecular mechanisms of cellular changes responsible for diabetic gastroparesis, primarily seen in middle-aged women, still remain incompletely defined. We hypothesized that a decrease in the expression, dimerization, and post-translational modification of neuronal nitric oxide synthase alpha (nNOSα) is estrogen mediated and responsible for the gender-specific prevalence of this malady.

METHODS

We induced diabetes by injecting male and female rats with streptozotocin. Male diabetic rats without gastroparesis were then injected with estrogen for 3 weeks and evaluated for gastroparesis development. Gastric tissues were analyzed for the elucidation of biochemical events associated with diabetes and gastroparetic dysfunction.

RESULTS

Although male diabetic, gastroparetic (either streptozotocin- or estrogen-induced) rats exhibited similarity in disease pathology to that of females, the molecular mechanisms of development were different. Our results indicate that slow gastric emptying in both male diabetic, gastroparetic rat groups was not associated with the level of expression of nNOSα in gastric tissues. However, nNOSα dimerization, which reflects nNOSα activation, did decline slightly in the antrum of diabetic males with estrogen-induced gastroparesis, suggesting a possible estrogen role. Females with diabetic gastroparesis, in contrast, demonstrated significantly impaired levels and dimerization of nNOSα in the antrum and pylorus. Although the precise mechanism remains unknown, nNOSα dimerization impairment in female antrum is apparently associated with reduced phosphorylation of Ser(1416) in the activation loop of nNOSα.

CONCLUSION

Taken together, these results demonstrate that gender and estrogens may be leading factors, through molecular changes involved in nitric oxide synthesis down-regulation, within the antrum and pylorus of female diabetic, gastroparetic rats.

Schisandra chinensis fruit extract attenuates albuminuria and protects podocyte integrity in a mouse model of streptozotocin-induced diabetic nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis fruit is widely used in Chinese medicine for the treatment of hepatic, renal, heart, cerebrovascular and infectious diseases.

AIM OF THE STUDY

To investigate the effects of Schisandra chinensis fruit extract (SE) on albuminuria and podocyte injury as well as the underlying mechanism in the mouse model of streptozotocin (STZ)-induced diabetic nephropathy and in cultured mouse podocyte cells.

MATERIALS AND METHODS

SE was orally administrated in STZ-induced diabetic nephropathy mice for 7 weeks, at a daily dose of 5g/kg body weight. The urinary albumin/creatinine ratio and urine albumin excretion rate were measured at the 6th and 9th week of the experiment. The extent of glomerulosclerosis and extracellular matrix deposition were determined by periodic acid-silver methenamine and Masson's trichrome staining. The amount of podocytes and the integrity of the slit diaphragm were detected by immunohistological staining of podocyte markers, Wilms' tumor 1 and nephrin. Alpha-smooth muscle actin, E-cadherin and plasminogen activator inhibitor-1 were measured by western blot and immunohistological staining to evaluate the level of epithelial-to-mesenchymal transition (EMT). Real-time reverse transcription PCR was used to detect the mRNA level of E-cadherin, alpha-SMA and snail in cultured podocyte cells.

RESULTS

Treatment with SE significantly decreased the urine albumin excretion rate and urinary albumin/creatinine ratio. In addition, SE attenuated glomerulosclerosis and protected against podocyte loss and integrity of the slit diaphragm. Furthermore, SE effectively prevented the EMT of podocytes caused by diabetic nephropathy.

CONCLUSIONS

Our studies suggest that SE might be beneficial for diabetic nephropathy. The effects of SE on attenuating albuminuria and glomerulosclerosis are possibly mediated by preserving podocyte integrity through suppressing EMT.

Antifibrotic effect of tamoxifen in a model of progressive renal disease

Tamoxifen, a selective estrogen receptor modulator, has antifibrotic properties; however, whether it can attenuate renal fibrosis is unknown. In this study, we tested the effects of tamoxifen in a model of hypertensive nephrosclerosis (chronic inhibition of nitric oxide synthesis with L-NAME). After 30 days, treated rats had significantly lower levels of albuminuria as well as lower histologic scores for glomerulosclerosis and interstitial fibrosis than untreated controls. Tamoxifen was renoprotective despite having no effect on the sustained, severe hypertension induced by L-NAME. Tamoxifen prevented the accumulation of extracellular matrix by decreasing the expression of collagen I, collagen III, and fibronectin mRNA and protein. These renoprotective effects associated with inhibition of TGF-β1 and plasminogen activator inhibitor-1, and with a significant reduction in α-smooth muscle actin-positive cells in the renal interstitium. Furthermore, tamoxifen abrogated IL-1β- and angiotensin-II-induced proliferation of fibroblasts from both kidney explants and from the NRK-49F cell line. Tamoxifen also inhibited the expression of extracellular matrix components and the production and release of TGF-β1 into the supernatant of these cells. In summary, tamoxifen exhibits antifibrotic effects in the L-NAME model of hypertensive nephrosclerosis, likely through the inhibition of TGF-β1, suggesting that it may have therapeutic use in CKD treatment.

Proteases in Plasma and Kidney of db/db Mice as Markers of Diabetes-Induced Nephropathy

Db/db mice are overweight, dyslipidemic and develop diabetic complications, relevant for similar complications in human type 2 diabetes. We have used db/db and db/+ control mice to investigate alterations in proteinase expression and activity in circulation and kidneys by SDS-PAGE zymography, electron microscopy, immunohistochemistry, Western blotting, and in situ zymography. Plasma from db/db mice contained larger amounts of serine proteinases compared to db/+ mice. Kidneys from the db/db mice had a significantly larger glomerular surface area and somewhat thicker glomerular basement membranes compared to the db/+ mice. Furthermore, kidney extracts from db/+ mice contained metalloproteinases with M_r of approximately 92000, compatible with MMP-9, not observed in db/db mice. These results indicate that higher levels of serine proteinases in plasma may serve as potential markers for kidney changes in db/db mice, whereas a decrease in MMP-9 in the kidney may be related to the glomerular changes.

The protective role of Smad7 in diabetic kidney disease: mechanism and therapeutic potential

OBJECTIVE

Although Smad3 has been considered as a downstream mediator of transforming growth factor-β (TGF-β) signaling in diabetes complications, the role of Smad7 in diabetes remains largely unclear. The current study tests the hypothesis that Smad7 may play a protective role and has therapeutic potential for diabetic kidney disease.

RESEARCH DESIGN AND METHODS

Protective role of Smad7 in diabetic kidney disease was examined in streptozotocin-induced diabetic mice that have Smad7 gene knockout (KO) and in diabetic rats given Smad7 gene transfer using an ultrasound-microbubble-mediated technique.

RESULTS

We found that mice deficient for Smad7 developed more severe diabetic kidney injury than wild-type mice as evidenced by a significant increase in microalbuminuria, renal fibrosis (collagen I, IV, and fibronectin), and renal inflammation (interleukin-1β [IL-1β], tumor necrosis factor-α [TNF-α], monocyte chemoattractant protein-1 [MCP-1], intracellular adhesion molecule-1 [ICAM-1], and macrophages). Further studies revealed that enhanced renal fibrosis and inflammation in Smad7 KO mice with diabetes were associated with increased activation of both TGF-β/Smad2/3 and nuclear factor-κB (NF-κB) signaling pathways. To develop a therapeutic potential for diabetic kidney disease, Smad7 gene was transferred into the kidney in diabetic rats by an ultrasound-microbubble-mediated technique. Although overexpression of renal Smad7 had no effect on levels of blood glucose, it significantly attenuated the development of microalbuminuria, TGF-β/Smad3-mediated renal fibrosis such as collagen I and IV and fibronectin accumulation and NF-κB/p65-driven renal inflammation including IL-1β, TNF-α, MCP-1, and ICAM-1 expression and macrophage infiltration in diabetic rats.

CONCLUSIONS

Smad7 plays a protective role in diabetic renal injury. Overexpression of Smad7 may represent a novel therapy for the diabetic kidney complication.

Midkine, a heparin-binding protein, is increased in the diabetic mouse kidney postmenopause

Estrogen is thought to protect against the development of chronic kidney disease, and menopause increases the development and severity of diabetic kidney disease. In this study, we used streptozotocin (STZ) to induce diabetes in the 4-vinylcyclohexene diepoxide (VCD)-treated mouse model of menopause. DNA microarrays were used to identify gene expression changes in the diabetic kidney postmenopause. An ANOVA model, CARMA, was used to isolate the menopause effect between two groups of diabetic mice, diabetic menopausal (STZ/VCD) and diabetic cycling (STZ). In this diabetic study, 8,864 genes of the possible 15,600 genes on the array were included in the ANOVA; 99 genes were identified as demonstrating a >1.5-fold up- or downregulation between the STZ/VCD and STZ groups. We randomly selected genes for confirmation by real-time PCR; midkine (Mdk), immediate early response gene 3 (IEX-1), mitogen-inducible gene 6 (Mig6), and ubiquitin-specific protease 2 (USP2) were significantly increased in the kidneys of STZ/VCD compared with STZ mice. Western blot analysis confirmed that Mdk and IEX-1 protein abundance was significantly increased in the kidney cortex of STZ/VCD compared with STZ mice. In a separate study, DNA microarrays and CARMA analysis were used to identify the effect of menopause on the nondiabetic kidney; VCD-treated mice were compared with cycling mice. Of the possible 15,600 genes on the array, 9,142 genes were included in the ANOVA; 20 genes were identified as demonstrating a >1.5-fold up- or downregulation; histidine decarboxylase and vanin 1 were among the genes identified as differentially expressed in the postmenopausal nondiabetic kidney. These data expand our understanding of how hormone status correlates with the development of diabetic kidney disease and identify several target genes for further studies.

Laminin isoform profiles in salivary glands in Sjögren's syndrome

Five different laminin (LM) alpha, four LM-beta, and three LM-gamma chains form the 15-16 currently known approximately 400-900 kDa heterodimeric LM-monomers, which self-assemble in the lamina lucida of the basement membrane (BM) to a network, connected with nidogens and perlecans with the underlying type IV collagen network. In labial salivary glands (LSG), the structurally organizing/polarizing BM separates the tubuloacinar epithelium from the connective tissue stroma but plays regulatory roles as well. Tissue distribution of LM-alpha, -beta, and -gamma chains is described, and application of the known combinatorial rules allows some conclusions also on the corresponding distribution of the LM-trimers. Currently, known integrin (Int) and non integrin (e.g., dystroglycans and Lutheran blood group antigens) LM-receptors are described. LMs are regulated at transcriptional, translational, and posttranslational levels, together with the regulation of alternative splicing, binding partners (assembly), secretion, and degradation. In LSGs, LM-alpha1, -alpha2, and -alpha4 are only found in the acinar (not ductal) BM, LM-alpha4 also in the periductal/ interstitial stroma. Pattern recognition disclosed irregular expression in the acinar BM, suggesting some dynamic and/or regulatory role. It seems that in a female-dominant autoimmune exocrinopathy, Sjögren's syndrome (SS), LM-alpha1 and -alpha2 are decreased, together with their Int alpha1beta1 and alpha2beta1 receptors. Because LM-111/211-to-Int-alpha1beta1/alpha2beta1 interactions play a crucial role in the transdifferentiation of the intercalated duct progenitors to secretory acinar cells, acinar remodeling is impaired in SS. Disturbed hemidesmosomal Int alpha6beta4/LM-332 interactions in SS may lead to acinar cell anoikis. Interestingly, dehydroepiandrosterone (DHEA) prohormone and its intracrine androgenic dihydrotestosterone (DHT) end product upregulate at least Int alpha1beta1/alpha2beta1, whereas LM-alpha1 is upregulated by outside-in LM-111/211-to-Int-alpha1beta1/alpha2beta1 signaling. It seems that LM alterations precede the lymphocyte infiltration, suggesting that acinar BM-Int pathology, perhaps related to endo- and intracrine sex steroid metabolism, represents an early pathogenic phases in SS.

Expression of aromatase, androgen and estrogen receptors in peripheral target tissues in diabetes

Our previous studies have shown that diabetes in the male streptozotocin (STZ)-induced diabetic rat is characterized by a decrease in circulating testosterone and concomitant increase in estradiol levels. Interestingly, this increase in estradiol levels persists even after castration, suggesting extra-testicular origins of estradiol in diabetes. The aim of the present study was to examine whether other target organs of diabetes may be sources of estradiol. The study was performed in male Sprague-Dawley non-diabetic (ND), STZ-induced diabetic (D) and STZ-induced diabetic castrated (Dcas) rats (n=8-9/group). 14 weeks of diabetes was associated with decreased testicular (ND, 26.3+/-4.19; D, 18.4+/-1.54; P<0.05), but increased renal (ND, 1.83+/-0.92; D, 7.85+/-1.38; P<0.05) and ocular (D, 23.4+/-3.66; D, 87.1+/-28.1; P<0.05) aromatase activity. This increase in renal (Dcas, 6.30+/-1.25) and ocular (Dcas, 62.7+/-11.9) aromatase activity persisted after castration. The diabetic kidney also had increased levels of tissue estrogen (ND, 0.31+/-0.01; D, 0.51+/-0.11; Dcas, 0.45+/-0.08) as well as estrogen receptor alpha protein expression (ND, 0.63+/-0.09; D, 1.62+/-0.28; Dcas, 1.38+/-0.20). These data suggest that in male STZ-induced diabetic rats, tissues other than the testis may become sources of estradiol. In particular, the diabetic kidney appears to produce estradiol following castration, a state that is associated with a high degree or renal injury. Overall, our data provides evidence for the extra-testicular source of estradiol that in males, through an intracrine mechanism, may contribute to the development and/or progression of end-organ damage associated with diabetes.

Effects of a surface topography composite with puerariae radix on human STRO-1-positive stem cells

Human skeletal stem cells (STRO-1 positive/STRO-1+) respond to different topographical features in various ways. On a flat surface these cells spread and tend to develop a fibroblast-like morphology. On a microgrooved surface enriched skeletal stem cell populations prefer to stretch along the grooves, which affects their cellular structure and differentiation, a phenomenon known as contact guidance. Growth factors, hormones and chemicals can also stimulate cell differentiation. A traditional Chinese medicine, puerariae radix, has previously been observed to stimulate bone formation. The active ingredients have been identified as isoflavones with estrogen-like bioactivity. This study combined the effects of microgrooved topology and hormone-like isoflavones in the biodegradable polymer polycaprolactone (PCL). Human osteogenic cells (STRO-1+) were cultured on flat PCL, grooved PCL and puerariae powder-impregnated grooved PCL for 5 weeks. Coomassie staining indicated that cell growth and survival was similar on flat PCL, grooved PCL and grooved PCL impregnated with 1 wt.% or 2 wt.% puerariae powder. Grooved PCL impregnated with 2 wt.% puerariae powder was observed to have an influence on protein expression, as observed by positive osteocalcin staining. Protein expression profiles were analyzed by difference gel electrophoresis to identify proteins that showed modulation of expression in response to these different environments. Overall, our results suggest that puerariae powder has an additive effect, along with microgrooved topographical stimulation, to promote changes in the STRO-1+ proteome that affect cell phenotype.

Gender-based reciprocal expression of transforming growth factor-beta1 and the inducible nitric oxide synthase in a rat model of cyclophosphamide-induced cystitis

BACKGROUND

The pluripotent cytokine transforming growth factor-beta1 (TGF-beta1) is the central regulator of inducible Nitric Oxide Synthase (iNOS) that is responsible for nitric oxide (NO) production in inflammatory settings. Previous studies have implicated a role for NO, presumably derived from iNOS, in cyclophosphamide (CYP)-induced cystitis in the bladder. TGF-beta1 is produced in latent form and requires dissociation from the latency-associated peptide (LAP) to act as primary anti-inflammatory and pro-healing modulator following tissue injury in the upper urinary tract. Since the role of TGF-beta1 in lower urinary tract inflammation is currently unknown, and since gender-based differences exist in the setting of interstitial cystitis (IC), the present study examined the relationship between TGF-beta1 and iNOS/NO in the pathogenesis of CYP-induced cystitis in both male and female rats.

METHODS

Sprague-Dawley rats, 4 months of age, of either gender were given 150 mg/kg CYP intraperitoneally. Urinary and bladder tissue TGF-beta1 and NO reaction products (NO2-/NO3-) were quantified as a function of time following CYP. Expression of active and latent TGF-beta1 as well as iNOS in harvested bladder tissue was assessed by immunohistochemistry.

RESULTS

Female rats had significantly higher levels of NO2-/NO3- in urine even at baseline as compared to male rats (p < 0.001), whereas there was no gender based significant difference in urine levels of active or latent TGF-beta1 prior to CYP injection. Inflammatory and cytotoxic changes were induced by CYP in the bladder of both sexes that were accompanied by differences in the urine levels of NO2-/NO3- and TGF-beta1. Male rats responded to CYP with significantly lower levels of NO2-/NO3- and significantly higher levels of TGF-beta1 in urine (p < 0.05) as compared to females at all time points after CYP. The urine levels of NO2-/NO3- after CYP were inversely correlated to latent and active TGF-beta1 (Pearson coefficient of -0.72 and -0.69 in females and -0.89 and -0.76 in males, respectively; p < 0.01). Bladder tissue of male rats exhibited significantly higher levels of both latent and active TGF-beta1 (p < 0.01) compared to female rats after CYP. TGF-beta1 and iNOS protein was mostly localized in the urothelium.

CONCLUSION

The results of this study suggest that there exists an inverse relationship between the expression of TGF-beta1 and iNOS/NO2-/NO3- in CYP-inflamed bladder. The gender of the animal appears to magnify the differences in urine levels of TGF-beta1 and NO2-/NO3- in this inflammatory setting. These results support the hypothesis that TGF-beta1 can suppress iNOS expression associated with bladder inflammation and reduce systemic levels of NO2-/NO3-, and further suggest that this feature of TGF-beta1 can be harnessed for therapy and diagnosis of interstitial cystitis.

Sex steroid hormones in diabetes-induced sexual dysfunction: focus on the female gender

INTRODUCTION

Diabetes is associated with gender-specific changes in sex steroid hormones. However, the mechanisms responsible for these associations as well as the link to sexual dysfunction are not well understood.

AIM

To discuss key clinical and laboratory findings linking diabetes, sex steroid hormones, and sexual dysfunction, with particular focus on the female gender.

METHODS

A comprehensive literature review was conducted using the PubMed database. Search terms were used in appropriate combinations, including diabetes, insulin, insulin sensitivity, androgen, estrogen, sexual function, women, men, estrogen receptor, and androgen receptor. Over 400 citations were selected, based on topical relevance, and examined for study methodology and major findings.

MAIN OUTCOME MEASURES

Data from peer-reviewed publications.

RESULTS

Imbalances in sex steroid hormone levels are strongly associated with diabetes and this may negatively impact upon sexual function. Although numerous factors are likely to contribute to the development of diabetes and its complications, the role of sex steroid hormones must be acknowledged.

CONCLUSIONS

Research related to diabetic women and sexual dysfunction is severely lacking. Identifying underlying causes for a given hormonal imbalance in diabetic patients, as well as determination of genetic and age-dependent factors, will become important in identifying the subpopulations in which hormonal replacement regimens will be most effective. Investigation into treating diabetic patients with adjunct hormonal therapies or steroid hormone receptor modulators holds much promise.

Transforming growth factor-beta and angiotensin in fibrosis and burn injuries

This review considers the roles of transforming growth factor-beta (TGF-beta), the signaling Smad proteins, and angiotensin II (AT II) in conditions leading to human fibrosis. The goal is to update the burn practitioner and researcher about this important pathway and to introduce AT II as a possible synergistic signal to TGF-beta in burn scarring. Literature searches of the MEDLINE database were performed for English manuscripts combinations of TGF-beta, Smad, angiotensin, fibrosis, burn, and scar. AT II and TGF-beta both activate the Smad protein system, which leads to the expression of genes related to fibrosis. In fibrotic conditions, such as tubulointerstitial nephritis, systemic sclerosis, and myocardial infarctions, AT II acts both independently and synergistically with TGF-beta. Both AT II and TGF-beta act through a messenger system, the Smad proteins that lead to excessive extracellular matrix formation. Treatment and research implications are reviewed. The interaction between AT II and TGF-beta leading to fibrosis is well described in some human diseases. This pathway may be of importance in human burn scarring as well.

Estradiol ameliorates diabetes-induced changes in vaginal structure of db/db mouse model

INTRODUCTION

Women with diabetes experience diminished genital arousal, reduced vaginal lubrication, vaginal atrophy, dyspareunia, and increased infections. Limited studies are available investigating the effects of diabetic complications on the vagina.

AIMS

The goals of this study were to investigate type 2 diabetes-induced changes in vaginal structure, and to determine if estradiol treatment ameliorates these changes.

METHODS

Eight-week-old female diabetic (db/db) mice (strain BKS*Cg-m+/+Lepr(db)/J) and age-matched control normoglycemic female littermates were used to investigate the effects of type 2 diabetes on vaginal tissue structural integrity. Diabetic animals were divided into two subgroups: diabetic treated with vehicle only and diabetic treated with pellets containing estradiol. At 16 weeks, the animals were sacrificed, and the vaginal tissues were excised and analyzed by histological and immunohistochemical methods to assess diabetes-induced changes in vaginal tissue and the extent by which these parameters are restored by estradiol treatment.

MAIN OUTCOME MEASURES

The effects of type 2 diabetes and estradiol supplementation were investigated on vaginal histoarchitecture.

RESULTS

Diabetic animals exhibited high blood glucose levels (>600 mg/dL), increased body weight (43.0 +/- 6.0 g vs. 24.4 +/- 2.0 g), and reduced plasma estradiol levels (65.5 +/- 6.6 pg/mL vs. 80.77 +/- 13.2 pg/mL) when compared to control animals. Diabetes resulted in significant thinning of the epithelium (P <or= 0.05), marked decrease in the muscularis area (P </= 0.05), distinct truncation of elastic fibers, and significant reduction of the nitrergic immunoreactive nerve fibers (P <or= 0.05). Treatment of diabetic animals with estradiol restored epithelial thickness (P <or= 0.05), muscularis area (P <or= 0.05), and elastic fiber distribution, and partially restored the density of nitrergic nerve fibers.

CONCLUSIONS

The data in this study demonstrate that type 2 diabetes disrupts vaginal structural integrity and that estradiol supplementation ameliorates the diabetes-induced vaginal pathology.

Association of common genetic variants in SMAD7 and risk of colon cancer

Two recent genome-wide association studies (GWAS) identified three common variants in SMAD7 (rs4464148, rs4939827 and rs12953717) that confer modest susceptibility to colorectal cancer. Here, we replicated the association of rs4464148 with colon cancer in a population-based case-control study (561 cases and 721 controls). Compared with the TT genotype, those with CT and CC had an adjusted odds ratio (OR) and 95% confidence interval of 1.06 (0.82-1.38) and 1.86 (1.17-2.96), respectively (P(trend) = 0.04). However, stratified analyses revealed that this association was limited to women only [OR = 1.25 (0.88-1.78) for CT and OR = 2.76 (1.53-4.98) for CC, P(trend) = 0.002, P(interaction) = 0.08], which was not noted in any GWAS. Similarly, we found evidence for association with both rs4939827 and rs12953717 in women only (P = 0.007 in dominant rs4939827 model and P = 0.015 in recessive rs12953717 model), but not in men (P > 0.05) and evidence of an interaction with gender (P = 0.015 for rs4939827 and P = 0.061 for rs12953717). Similar effect modification was found in haplotype analyses. Our data add evidence supporting these genetic variants as markers predisposing to colon cancer, specifically in women.

Estradiol restores diabetes-induced reductions in sex steroid receptor expression and distribution in the vagina of db/db mouse model

Sex steroid hormones and receptors play an important role in maintaining vaginal physiology. Disruptions in steroid receptor signaling adversely impact vaginal function. Limited studies are available investigating the effects of diabetic complications on steroid receptor expression and distribution in the vagina. The goals of this study were to investigate type 2 diabetes-induced changes in expression, localization and distribution of estrogen (ER), progesterone (PR) and androgen receptors (AR) in the vagina and to determine if estradiol treatment ameliorates these changes. Eight-week-old female diabetic (db/db) mice (strain BKS.Cg-m+/+ Lepr(db)/J) were divided into two subgroups: untreated diabetic and diabetic animals treated with pellets containing estradiol. Control normoglycemic littermates were subcutaneously implanted with pellets devoid of estradiol. At 16 weeks of age, animals were sacrificed, vaginal tissues excised and analyzed by Western blot and immunohistochemical methods. Diabetes produced marked reductions in protein expression of ER, PR, and AR. Diabetes also resulted in marked differences in the distribution, staining intensity and proportion of immunoreactive cells containing these steroid receptors in the epithelium, lamina propria and muscularis. Treatment of diabetic animals with estradiol restored receptor protein expression and distribution similar to those levels observed in control animals. This study demonstrates that type 2 diabetes markedly reduces steroid receptor protein expression and distribution in the vagina. Estradiol treatment of diabetic animals ameliorates these diabetes-induced changes.

17 beta-estradiol and tamoxifen upregulate estrogen receptor beta expression and control podocyte signaling pathways in a model of type 2 diabetes

Diabetic nephropathy remains one of the most important causes of end-stage renal disease. This is particularly true for women from racial/ethnic minorities. Although administration of 17beta-estradiol to diabetic animals has been shown to reduce extracellular matrix deposition in glomeruli and mesangial cells, effects on podocytes are lacking. Given that podocyte injury has been implicated as a factor leading to the progression of proteinuria and diabetic nephropathy, we treated db/db mice, a model of type 2 diabetic glomerulosclerosis, with 17beta-estradiol or tamoxifen to determine whether these treatments reduce podocyte injury and decrease glomerulosclerosis. We found that albumin excretion, glomerular volume, and extracellular matrix accumulation were decreased in these mice compared to placebo treatment. Podocytes isolated from all treatment groups were immortalized and these cell lines were found to express the podocyte markers WT-1, nephrin, and the TRPC6 cation channel. Tamoxifen and 17beta-estradiol treatment decreased podocyte transforming growth factor-beta mRNA expression but increased that of the estrogen receptor subtype beta protein. 17beta-estradiol, but not tamoxifen, treatment decreased extracellular-regulated kinase phosphorylation. These data, combined with improved albumin excretion, reduced glomerular size, and decreased matrix accumulation, suggest that both 17beta-estradiol and tamoxifen may protect podocytes against injury and therefore ameliorate diabetic nephropathy.

Sex, diabetes and the kidney

The incidence and the rate of progression of nondiabetic renal disease is generally greater in men compared with age-matched women, suggesting that the female sex is protective and/or that the male sex is a risk factor for the development and progression of nondiabetic renal disease. In diabetes, even though the male sex still appears to be a risk factor, this relationship is not as strong as it is in nondiabetic renal disease. Experimental evidence suggests that both estrogens and androgens play an important role in the pathophysiology of renal disease. Thus one of the potential mechanisms for the absence of a clear sex difference in the setting of diabetes may be alterations in sex hormone levels. Indeed, studies suggest that diabetes is a state of an imbalance in sex hormone levels; however, whether these changes correlate with the decline in renal function associated with diabetes is unclear. Furthermore, diabetic renal disease rarely develops before puberty, and the onset of puberty accelerates microalbuminuria, supporting the idea of the involvement of sex hormones in the development and progression of the disease. However, other than a handful of experimental studies indicating that treatment with or removal of sex hormones alters the course of diabetic renal disease, very few studies have actually directly examined the correlation between sex hormones and the disease development and progression. Further studies are necessary to determine the precise contribution of sex hormones in the pathophysiology of diabetic renal disease to develop novel and potentially sex-specific therapeutic treatments.

Sex and the renin-angiotensin system: inequality between the sexes in response to RAS stimulation and inhibition

The purpose of this review is to examine sex differences in response to stimulation and inhibition of the renin-angiotensin system (RAS). The RAS plays a prominent role in the development of chronic renal disease, and there are known sex differences not only in the expression level of components of the RAS but also in how males and females respond to perturbations of the RAS. In men, renal injury increases in parallel with increased activation of the RAS, while in women, increases in ANG II do not necessarily translate into increases in renal injury. Moreover, both epidemiological and experimental studies have noted sex differences in the therapeutic benefits following angiotensin-converting enzyme inhibitor and angiotensin receptor blocker treatment. Despite these differences, RAS inhibitors are the most commonly prescribed drugs for the treatment of chronic renal disease, irrespective of sex. This review will examine how males and females respond to stimulation and inhibition of the RAS, with a focus on renal disease.

Imbalance in sex hormone levels exacerbates diabetic renal disease

Studies suggest that the presence of testosterone exacerbates, whereas the absence of testosterone attenuates, the development of nondiabetic renal disease. However, the effects of the absence of testosterone in diabetic renal disease have not been studied. The study was performed in male Sprague-Dawley nondiabetic, streptozotocin-induced diabetic, and streptozotocin-induced castrated rats (n=10 to 11 per group) for 14 weeks. Diabetes was associated with the following increases: 3.2-fold in urine albumin excretion, 6.3-fold in glomerulosclerosis, 6.0-fold in tubulointerstitial fibrosis, 1.6-fold in collagen type I, 1.2-fold in collagen type IV, 1.3-fold in transforming growth factor-beta protein expression, and 32.7-fold in CD68-positive cell abundance. Diabetes was also associated with a 1.3-fold decrease in matrix metalloproteinase protein expression and activity. Castration further exacerbated all of these parameters. Diabetes was also associated with a 4.7-fold decrease in plasma testosterone, 2.9-fold increase in estradiol, and 2.1-fold decrease in plasma progesterone levels. Castration further decreased plasma testosterone levels but had no additional effects on plasma estradiol and progesterone. These data suggest that diabetes is associated with abnormal sex hormone levels that correlate with the progression of diabetic renal disease. Most importantly, our results suggest an important role for sex hormones in the pathophysiology of diabetic renal complications.

Fetal deaths in Alabama, 1974-1983: a birth weight-specific analysis

Objective. Although angiotensin II-mediated inflammation and extracellular matrix accumulation are considered to be associated with the progression of diabetic nephropathy, these processes have not yet been sufficiently clarified. The objective of this study was to determine whether the correction of the abnormal renal expression of MMPs and its inhibitors (MMPs/TIMPs) and cytokines following the administration of aliskiren to KK-A^y mice results in a renoprotective effect. Methods. KK-A^y mice were divided into two groups, that is, untreated (saline) and treated (aliskiren) groups. Systolic BP, HbA1c levels, and the albumin-creatinine ratio (ACR) were measured. The renal expression of MMPs/TIMPs, fibronectin, type IV collagen, MCP-1, and (pro)renin receptor ((P)RR) was examined using real-time PCR and/or immunohistochemical staining. Renal MAPK and NF-κB activity were also examined by Western blot analyses and ELISA, respectively. Results. Significant decreases in systolic BP and ACR levels were observed in treated KK-A^y mice compared with the findings in untreated KK-A^y mice. Furthermore, increases in MMPs/TIMPs, fibronectin, type IV collagen, MCP-1, and (P)RR expression, in addition to MAPK and NF-κB activity, were significantly attenuated by aliskiren administration. Conclusions. It appears that aliskiren improves albuminuria and renal fibrosis by regulating inflammation and the alteration of collagen synthesis and degradation.