Glomerular Area Research Articles

Effect of moderate exercise on renal changes and oxidative stress in ovariectomized rats with type 1 diabetes mellitus

This study evaluated the aerobic exercise effects of moderate and progressive intensity on renal function and structure, and oxidative stress in ovariectomized rats with type 1 diabetes mellitus induced by streptozotocin (STZ). Eighteen Wistar rats were divided into 3 groups: OSC - ovariectomized and sedentary control rats; OSD - ovariectomized and sedentary diabetic rats; and OTD - ovariectomized and trained diabetic rats. After induction of diabetes, the OTD group was submitted to eight weeks of exercise. Twenty-four hours after the last training session urine samples were collected. Blood samples and kidneys were collected after euthanasia for renal function analysis, histology, morphometry and oxidative stress. Our results have shown a reduction of the weight gain, increase of kidney weight and postprandial glycemia in diabetic rats. However, exercise decreased glycosuria and prevented the proteinuria in OTD group rats. Focal segmental glomerulosclerosis (FSGS), juxtamedullary glomerular tuft area, tubulointerstitial lesions (TIL), brush border loss and tubular cell debridement were reduced in OTD rats. In addition, exercise training decreased urinary and plasma concentrations of thiobarbituric acid reactive substance (TBARS). Our results demonstrate the beneficial effect of progressive aerobic exercise on proteinuria, glycosuria, and renal structure in ovariectomized diabetic rats, which may be mediated in part by reduction of oxidative stress.

A case of IgA nephropathy with deep venous thrombosis in the mesentery and lower extremities

IgA nephropathy (Berger disease) is a disorder in which there is prominent IgA deposition in the glomerular mesangial area, and is the most common type of primary glomerulonephritis (1), receiving more and more attention (2-8). With diverse clinical manifestations, it has its own characteristic type of glomerular mesangial lesions (9).

Active vitamin D regulates macrophage M1/M2 phenotypes via the STAT-1-TREM-1 pathway in diabetic nephropathy.

Imbalance of M1/M2 macrophages phenotype activation is a key point in diabetic nephropathy (DN). This study aimed to investigate whether active vitamin D (VD) suppresses macrophage transition to the M1 phenotype via inhibiting the high glucose-induced STAT-1 phosphorylation to reduce TREM-1 expression. In vivo, pathological changes in kidney tissue were detected and the expression of CD68 TREM-1, STAT-1, M1 makers, and M2 makers were acquired in renal tissue of patients with DN and 18w DN rats. In vitro, RAW 264.7 cells were incubated in the presence of high glucose with or without VD. Silencing and overexpression of TREM-1 and silencing and activate of STAT-1 were explored to elucidate the underlying mechanism. The expression of TREM-1 and STAT-1 and the changes of macrophage phenotype were examined separately by western blot and immunofluorescence staining. (a) Expression of TREM-1, p-STAT-1, and M1 markers (iNOS and TNF-α) were increased and positively correlated in kidneys from patients with DN. (b) In DN rats, the enlargement of glomerular surface area, expansion of glomerular mesangial matrix, the expression of CD68, TREM-1, p-STAT-1, and M1 marker (iNOS) were significantly increased in comparison with the normal control group, whereas above changes were markedly decreased in the diabetic group treated with the VD group. (c) In vitro, VD significantly decreased high glucose-induced CD68, TREM-1, p-STAT-1, and M1 marker (iNOS) expression. However, above-mentioned effects of VD are abolished when TREM-1 is overexpressed or STAT-1 is activated. Reductions in STAT-1 expression decreased the TREM-1 expression. VD can inhibit macrophage transition to the M1 phenotype through the STAT-1/TREM-1 pathway.

Inhibiting the urokinase‐type plasminogen activator receptor system recovers STZ‐induced diabetic nephropathy

The urokinase‐type plasminogen activator (uPA) receptor (uPAR) participates to the mechanisms causing renal damage in response to hyperglycaemia. The main function of uPAR in podocytes (as well as soluble uPAR ‐(s)uPAR‐ from circulation) is to regulate podocyte function through αvβ3 integrin/Rac‐1. We addressed the question of whether blocking the uPAR pathway with the small peptide UPARANT, which inhibits uPAR binding to the formyl peptide receptors (FPRs) can improve kidney lesions in a rat model of streptozotocin (STZ)‐induced diabetes. The concentration of systemically administered UPARANT was measured in the plasma, in kidney and liver extracts and UPARANT effects on dysregulated uPAR pathway, αvβ3 integrin/Rac‐1 activity, renal fibrosis and kidney morphology were determined. UPARANT was found to revert STZ‐induced up‐regulation of uPA levels and activity, while uPAR on podocytes and (s)uPAR were unaffected. In glomeruli, UPARANT inhibited FPR2 expression suggesting that the drug may act downstream uPAR, and recovered the increased activity of the αvβ3 integrin/Rac‐1 pathway indicating a major role of uPAR in regulating podocyte function. At the functional level, UPARANT was shown to ameliorate: (a) the standard renal parameters, (b) the vascular permeability, (c) the renal inflammation, (d) the renal fibrosis including dysregulated plasminogen‐plasmin system, extracellular matrix accumulation and glomerular fibrotic areas and (e) morphological alterations of the glomerulus including diseased filtration barrier. These results provide the first demonstration that blocking the uPAR pathway can improve diabetic kidney lesion in the STZ model, thus suggesting the uPA/uPAR system as a promising target for the development of novel uPAR‐targeting approaches.

Low birth weight associates with glomerular area in young male IgA nephropathy patients

BackgroundIn a recent study we demonstrated that low birth weight (LBW) was associated with increased risk of progressive IgA nephropathy (IgAN). In the present study we investigate whether this could be explained by differences in glomerular morphological parameters.MethodsThe Medical Birth Registry of Norway has registered all births since 1967 and the Norwegian Kidney Biopsy Registry has registered all kidney biopsies since 1988. Patients diagnosed with IgAN, registered birth weight and estimated glomerular filtration rate above 60 ml/min/1.73m2 at time of diagnosis were eligible for inclusion. Patients were included in a case-control manner based on whether or not they had LBW or were small for gestational age (SGA). Glomerular area, volume and density were measured using high resolution digital images and differences were compared between groups.ResultsWe included 51 IgAN patients with a mean age of 23.6 years, 47.1% male. Compared to IgAN patients without LBW or SGA, IgAN patients with LBW and/or SGA had larger glomerular area (16,235 ± 3744 vs 14,036 ± 3502 μm2, p-value 0.04). This was significant for total cohort and male but not female. On separate analysis by gender, glomerular area was significantly larger only in males (17,636 ± 3285 vs 13,346 ± 2835 μm2, p-value 0.004). Glomerular density was not different between groups. In adjusted linear regression analysis, glomerular area was negatively associated with birth weight.ConclusionAmong young adult IgAN patients, low birth weight is associated with having larger glomerular area, especially in males. Larger glomeruli may be a sign of congenital nephron deficit that may explain the increased risk of progressive IgAN.

Detection and identification of potential transglutaminase 2 substrates in the mouse renal glomeruli

The glomerulus primarily comprises mesangial cells, glomerular microvascular endothelial cells, and podocytes. IgA nephropathy is the most common primary glomerulonephritis worldwide and has a risk of progression to end-stage renal disease. IgA nephropathy is characterized by predominant IgA deposition in the glomerular mesangial area, where TG2 is significantly enhanced. Therefore, identification of glomerular TG2 substrates is the first step in elucidating the role of TG2 as a crosslinking enzyme during disease progression. To clarify potential glomerular TG2 substrates, and to establish a procedure for substrate identification, we attempted to identify those molecules using normal mouse glomeruli. Extracts from mouse glomerular and non-glomerular fractions were treated with our established biotin-labeled substrate peptide, which specifically crosslinks to the lysine-donor substrates depending on TG2 activity. Peptide-incorporated proteins were then purified using avidin resin and identified via mass spectrometry. In parallel, we performed the identification using corresponding samples from TG2 knockout mice. Consequently, potential TG2 substrates were separately identified in glomerular and non-glomerular fractions. They were mainly identified as novel TG2 substrates and partly include the well-known substrates. These results potentially provide novel insights into the mechanism underlying IgA nephropathy and may help elucidate the physiological functions of TG2.

5-Aminolevulinic acid with ferrous iron improves early renal damage and hepatic steatosis in high fat diet-induced obese mice.

5-Aminolevulinic acid, a natural amino acid, activates mitochondrial respiration and induces heme oxygenase-1 expression. Obesity and type 2 diabetes mellitus are associated with age-related mitochondrial respiration defect, oxidative stress and inflammation. The aim of this study is to investigate the effects of 5-aminolevulinic acid with sodium ferrous citrate on early renal damage and hepatic steatosis. 7-Month-old C57BL/6 mice were fed with a standard diet or high fat diet for 9 weeks, which were orally administered 300 mg/kg 5-aminolevulinic acid combined with 47 mg/kg sodium ferrous citrate (5-aminolevulinic acid/sodium ferrous citrate) or vehicle for the last 5 weeks. We observed that 5-aminolevulinic acid/sodium ferrous citrate significantly decreased body weight, fat weight, hepatic lipid deposits and improved levels of blood glucose and oral glucose tolerance test. In addition, 5-aminolevulinic acid/sodium ferrous citrate suppressed increased glomerular tuft area in high fat diet-fed mice, which was associated with increased heme oxygenase-1 protein expression. Our findings demonstrate additional evidence that 5-aminolevulinic acid/sodium ferrous citrate could improve glucose and lipid metabolism in diabetic mice. 5-Aminolevulinic acid/sodium ferrous citrate has potential application in obesity or type 2 diabetes mellitus-associated disease such as diabetic nephropathy and nonalcoholic fatty liver disease.

A2430 Glomerulomegaly and blood pressure may predict renal progression after 10 yrs in IgA nephropathy

Objectives: We previously reported that blood pressure (BP) and glomerular size are related to pathologic findings and renal function in IgAN. We reanalyzed these effects on long-term renal progression. Methods: We analyzed renal biopsy specimens and clinical information in patients with IgAN (n = 34). Glomerular surface area (GSA) was determined using a computer imaging analyzer. Results: There were significant correlations between mean or maximal GSA and age, body mass index, systolic and diastolic BP, eGFR, and pathological findings including glomerulosclerosis, interstitial fibrosis, and tubular atrophy. The group with higher GSA had higher BP, pathological grade and lower eGFR. Twenty-two patients with initial normal serum creatinine levels were followed up for >10 yrs. As well as GSA was reversely correlated with final eGFR, GSA and initial BP were higher in the progressor group (n = 6; two on hemodialysis) than in the normal group (n = 16). Conclusion: These results suggest that glomerulomegaly and BP may predict the long-term renal progression in IgA nephropathy.

The expression of two isoforms of matrix metalloproteinase-2 in aged mouse models of diabetes mellitus and chronic kidney disease.

BackgroundThis study was undertaken to explore the effects of aging on the kidneys in mouse models of diabetes and chronic kidney disease (CKD), and to compare the expression of two isoforms of matrix metalloproteinase-2 (MMP-2)–secretory full-length MMP-2 and intracellular N-terminal truncated MMP-2 (NTT-MMP-2)–in these models.MethodsTwo experimental ICR mouse models were used: a streptozotocin (STZ)-induced type 1 diabetes mellitus model and a 5/6 nephrectomized (5/6Nx) CKD model. The abundance of each isoform of MMP-2 was determined by quantitative polymerase chain reaction (qPCR), and functional analyses were conducted. Moreover, the protein levels of the two MMP-2 isoforms were determined semi-quantitatively by immunohistochemical staining, and their association with tissue damage was assessed.ResultsBoth isoforms of MMP-2 were upregulated in the kidney tissues of STZ-induced diabetic mice and 5/6Nx mice, irrespective of age. Characteristically, NTT-MMP-2 protein expression was elevated in old control mice, in line with the qPCR results. NTT-MMP-2 expression was limited to the renal cortex, and to the tubulointerstitial area rather than the glomerular area. In terms of tissue damage, tubulointerstitial fibrosis was more severe in old 5/6Nx mice than in their young counterparts, whereas glomerulosclerosis was comparable in old and young 5/6Nx mice.ConclusionThe intracellular isoform of MMP-2 was induced by ageing, irrespective of the presence of diabetes or CKD, and its induction may be related to tubulointerstitial fibrosis in chronic kidney disease.

Abstract 122: Deletion of Gstm1 Results in Poor Survival and Exaggerated Kidney Injury Associated With Increased Oxidative Stress and Apoptosis in a Mouse Model of Chronic Kidney Disease

In humans, a common deletion variant of the GSTM1 gene, the GSTM1(0) null allele, results in decreased GSTM1 enzymatic activity and is associated with higher levels of oxidative stress. We reported that GSTM1(0) is associated with increased risks of chronic kidney disease (CKD) progression and death in the African Americans Study of Kidney Disease. To establish a causal relationship between GSTM1 deficiency and CKD progression, we deleted Gstm1 in the mouse, and determined its effect in the sub-total nephrectomy (Nx) model of CKD. After the 8 th week after Nx, 4 out of 8 Gstm1 knockout (KO) mice began to die, whereas wild-type (WT) mice had 100% survival by the study endpoint at 13 th week. Remaining KO mice had significantly higher plasma creatinine (p < 0.05), suggestive of lower GFR. Due to early mortality in KO mice after the 8th week after Nx, we phenotyped mice at the 8 th week (n=6 each). KO mice had significantly higher 1) mean systolic blood pressure (by radiotelemetry): KO 157.2 ± 5, WT 141.1 ± 2.4 mmHg, 2) urine albumin/creatinine ratio (μg/mg): KO 748.4 ± 187.9, WT 235.1 ± 24.6, and 3) renal superoxide (O2·-) levels (counts/min/mg dry tissue): KO 249.7 ± 63; WT 74.5 ± 14.7; P ≤ 0.02. Hydrogen peroxide levels were not different. Renal mRNA levels of the superoxide dismutase isoforms SOD1, SOD2, and SOD3 were significantly lower in KO mice (KO 7.78 ± 0.047, 0.446 ± 0.062, 0.18 ± 0.03; WT 10.64 ± 0.43, 2.432 ± 0.386, 1.188 ± 0.124, respectively, P ≤ 0.003. Total kidney pathology score (KO 18.7 ± 1.5; WT 8 ± 0.6; P <0.0001) showed that KO mice had worse kidney injury, with severe glomerulosclerosis, proteinaceous casts, and chronic inflammation. Both glomerular surface area (SA)/total non-infarcted kidney area (KO 3.347 ± 0.301; WT 2.286 ± 0.268; P = 0.02) and mesangial SA/glomerular SA (KO 35.62 ± 2.219; WT 23.6 ± 2.569; P = 0.005) were significantly increased in KO mice. GSTM1 has also been shown to suppress ASK1 - the apoptosis signal-regulating kinase 1 that induces apoptosis via activation of caspase-3. Consistent with activated ASK1 pathway, KO mice had significantly higher renal TUNEL staining and caspase-3 protein levels (KO 3.594 ± 0.327; WT 2.511 ± 0.208; P = 0.01). In conclusion, in CKD, loss of GSTM1 leads to deleterious outcome associated with increased O2·- levels and apoptosis.

Complement activation associated with ADAMTS13 deficiency may contribute to the characteristic glomerular manifestations in Upshaw-Schulman syndrome

IntroductionUpshaw-Schulman syndrome (USS) is a congenital form of thrombotic thrombocytopenic purpura (TTP) associated with loss-of-function mutations in the ADAMTS13 gene, possibly leading to aberrant complement activation and vascular injury. However, USS is extremely rare, and there have been no systematic studies correlating histopathological severity with local ADAMTS13 expression and complement activation. Materials and methodsHere, we compared histopathological features, ADAMTS13 immunoreactivity, and immunoreactivity of complement proteins C4d and C5b-9 among renal biopsy tissues from five USS cases, ten acquired TTP cases, and eleven controls. ResultsPathological analysis revealed chronic glomerular sclerotic changes in the majority of USS cases (4 of 5), with minor glomerular pathology in the remaining case. In two of these four severe cases, more than half of the glomerular segmental sclerosis area was localized in the perihilar region. The average number of ADAMTS13-positive cells per glomerulus was significantly lower in USS cases than controls (p < 0.05). Conversely, C4d staining was significantly more prevalent in the glomerular capillary walls of USS cases than controls (p < 0.05), while C5b-9 staining did not differ significantly among groups. ConclusionsThese findings suggest that the severity of glomerular injury in USS is associated with deficient ADAMTS13 expression and local complement activation, particularly in vascular regions with higher endothelial shear stress. We suggest that C4d immunostaining provides evidence for complement-mediated glomerular damage in USS.

Aflatoxin induced renal toxicity in Albino rats and the ameliorative effect of green tea aqueous extract: Histological, Morphometric and Immuno-histochemical Study

Tea is the most common drink worldwide besides water. It is rich in antioxidant polyphenolic flavonoids. Further, it has anti-apoptotic, anti-inflammatory, and autoantigen-inhibitory properties. To evaluate the effects of oral administration of aqueous extract of green tea against experimental aflatoxicosis on the renal tissues of adult male albino rats. Twenty five adult male rats were included and they were divided equally into 5 groups: Group 1 (aflatoxin group): the rats received aflatoxins (2.5 mg/kg diet for 15 days), group 2 (aflatoxins and green tea aqueous extract group) for 15 days, group 3, the rats received aflatoxins for 15 days and aqueous extract of the green tea for 30 days, group 4 (green tea aqueous extract group) and group 5(control negative group). Detailed non-traditional histological and morphometrical analyses for renal tissues stained with Hematoxylin and Eosin, Masson's trichrome stain, Periodic Acid Schiff’s (PAS), Alizarin red S stains and immunohistochemical detection of Ki-67 were done. The main observed renal lesions in rats received aflatoxins were dilatation of the renal pelvis, increases in glomerular areas (GA), widening of Bowman's spaces and necrosis of the renal lining epithelium and proliferation of fibrous connective tissues. Morphometric analysis revealed the presence of significant difference between group I and the other experimental groups. Meanwhile, groups 2 and 3 revealed a significant improvement in the histological changes and decrease in most of parameters. The highest percentage of PAS positive reaction was significantly found in group 4. Quantitative analysis of positive reactions of Ki-67 revealed the highest positive immunohistochemical reactions were detected in group 1 which significantly different in groups 4 and 5. In conclusion, green tea has a protective effect against the adverse effects of aflatoxins on renal tissues evidenced by improvement of histopathological alterations and regulation of Ki-67 expressions.&#x0D;

Glycine mitigates renal oxidative stress by suppressing Nox4 expression in rats with streptozotocin-induced diabetes

Glycine exerts renoprotective effects, but the mechanism remains unclear. Glycine is increasingly recognized as a factor that attenuates oxidative stress, a key mechanism underlying diabetic nephropathy. In this study, we investigated the effects of glycine on diabetic renal injury and oxidative stress by adding 1% glycine in the drinking water of rats with streptozotocin-induced diabetes for 20 weeks. Glycine levels decreased in the plasma and kidney homogenates of diabetic rats but were restored by oral glycine administration. In these diabetic rats, glycine attenuated renal damage, as evidenced by the decreased mesangial expansion, tubular interstitial fibrosis, and neutrophil gelatinase-associated lipocalin (NGAL) expression. Glycine also ameliorated the raise in urinary malondialdehyde (MDA) levels and partially restored renal glutathione levels in diabetic rats. Renal levels of the Nox4 mRNA and protein, a major source of renal oxidative stress, were suppressed by the treatment with glycine. Immunohistological analysis revealed that glycine had protective effects on the tubular area rather than the glomerular area. Our results strongly suggest that the protective effect of glycine on renal oxidative stress and structural damage may be linked to enhancement of GSH synthesis and suppression of renal Nox4 expression in diabetic rats.

A maternal low-protein diet and neonatal overnutrition result in similar changes to glomerular morphology and renal cortical oxidative stress measures in male Wistar rats.

There is a strong correlation between inadequate gestational and postpartum nutrition and the occurrence of cardiovascular diseases. The present study investigated the effects of a maternal low-protein diet and neonatal overfeeding on the oxidative balance and morphology of the renal cortex of male Wistar rats. Two independent protocols were used. First, pregnant Wistar rats received diets containing either 17% (normal protein) or 8% (low protein) casein throughout pregnancy and lactation. Second, the litter size was reduced by one-third on the third postnatal day to induce overnourishment in offspring. At 30 days, the oxidative balance and morphology of the renal cortex were analyzed. There was a small but significant increase in renal corpuscle area in the low protein (LP, 5%) and overnutrition (ON, 8%) groups. Glomerular tuft area also increased in LP (6%) and ON (9%), as did glomerular cellularity (LP, +11%; ON, +12%). In the oxidative stress analyses, both nutritional insults significantly elevated lipid peroxidation (LP, +18%; ON, +135%) and protein oxidation (LP, +40%; ON, +65%) while significantly reducing nonenzymatic antioxidant defenses, measured as reduced glutathione (LP, -32%; ON, -45%) and total thiol content (LP, -28%; ON, -24%). We also observed a decrease in superoxide dismutase (LP, -78%; ON, -51%), catalase (LP, -18%; ON, -61%), and glutathione S-transferase (only in ON, -44%) activities. Our results demonstrate that nutritional insults, even those of a very different nature, during perinatal development can result in similar changes in oxidative parameters and glomerular morphology in the renal cortex.

Combining SGLT2 Inhibition With a Thiazolidinedione Additively Attenuate the Very Early Phase of Diabetic Nephropathy Progression in Type 2 Diabetes Mellitus.

Although both sodium glucose co-transporter 2 inhibition by dapagliflozin and thiazolidinedione, pioglitazone have glucose-lowering and anti-inflammatory effects, the therapeutic efficacy of their combination on diabetic nephropathy has not been investigated. 9-week-old male db/db mice were randomly assigned to 4 groups and administrated with (1) vehicle, (2) dapagliflozin, (3) pioglitazone, or (4) dapagliflozin and pioglitazone combination. Human proximal tubule (HK-2) cells were treated with glucose or palmitate acid in the presence of medium, dapagliflozin, pioglitazone, or both. Glomerular tuft area and mesangial expansion of the kidney more reduced in the combination group compared to control and single therapy groups. Podocyte foot process width and glomerular basement membrane thickness decreased regardless of treatment, while the combination group showed the slowest renal hypertrophy progression (P < 0.05). The combination treatment decreased MCP-1, type I and IV collagen expression in the renal cortex. Only the combination treatment decreased the expression of angiotensinogen, IL-6, and TGF-β while it enhanced HK-2 cell survival (all P < 0.05). In conclusion, dapagliflozin and pioglitazone preserved renal function, and combination therapy showed the greatest benefit. These findings suggest that the combination therapy of dapagliflozin with pioglitazone is more effective than the single therapy for preventing the progression of nephropathy in patients with type 2 diabetes.

Selective abdominal venous congestion to investigate cardiorenal interactions in a rat model.

Abdominal congestion may play an important role in the cardiorenal syndrome and has been demonstrated to drive disease progression. An animal model for abdominal congestion, without other culprit mechanisms that are often present in patients such as low cardiac output or chronic kidney disease, might be interesting to allow a better study of the pathophysiology of the cardiorenal syndrome. The objective of this study was to develop a clinically relevant and valid rat model with abdominal venous congestion and without pre-existing heart and/or kidney dysfunction. To do so, a permanent surgical constriction (20 Gauge) of the thoracic inferior vena cava (IVC) was applied in male Sprague Dawley rats (IVCc, n = 7), which were compared to sham-operated rats (SHAM, n = 6). Twelve weeks after surgery, abdominal venous pressure (mean: 13.8 vs 4.9 mmHg, p < 0.01), plasma creatinine (p < 0.05), plasma cystatin c (p < 0.01), urinary albumin (p < 0.05), glomerular surface area (p < 0.01) and width of Bowman’s space (p < 0.05) of the IVCc group were significantly increased compared to the SHAM group for a comparable absolute body weight between groups (559 vs 530g, respectively, p = 0.73). Conventional cardiac echocardiographic and hemodynamic parameters did not differ significantly between both groups, indicating that cardiac function was not compromised by the surgery. In conclusion, we demonstrate that constriction of the thoracic IVC in adult rats is feasible and significantly increases the abdominal venous pressure to a clinically relevant level, thereby inducing abdominal venous congestion.

Renal injury in Seipin-deficient lipodystrophic mice and its reversal by adipose tissue transplantation or leptin administration alone: adipose tissue-kidney crosstalk.

Seipin deficiency is responsible for type 2 congenital generalized lipodystrophy with severe loss of adipose tissue (AT) and could lead to renal failure in humans. However, the effect of Seipin on renal function is poorly understood. Here we report that Seipin knockout (SKO) mice exhibited impaired renal function, enlarged glomerular and mesangial surface areas, renal depositions of lipid, and advanced glycation end products. Elevated glycosuria and increased electrolyte excretion were also detected. Relative renal gene expression in fatty acid oxidation and reabsorption pathways were impaired in SKO mice. Elevated glycosuria might be associated with reduced renal glucose transporter 2 levels. To improve renal function, AT transplantation or leptin administration alone was performed. Both treatments effectively ameliorated renal injury by improving all of the parameters that were measured in the kidney. The treatments also rescued insulin resistance and low plasma leptin levels in SKO mice. Our findings demonstrate for the first time that Seipin deficiency induces renal injury, which is closely related to glucolipotoxicity and impaired renal reabsorption in SKO mice, and is primarily caused by the loss of AT and especially the lack of leptin. AT transplantation and leptin administration are two effective treatments for renal injury in Seipin-deficient mice.-Liu, X.-J., Wu, X.-Y., Wang, H., Wang, S.-X., Kong, W., Zhang, L., Liu, G., Huang, W. Renal injury in Seipin-deficient lipodystrophic mice and its reversal by adipose tissue transplantation or leptin administration alone: adipose tissue-kidney crosstalk.

Renoprotective impact of estrogen receptor-α and its splice variants in female mice with type 1 diabetes.

Estrogen has been implicated in the regulation of growth and immune function in the kidney, which expresses the full-length estrogen receptor-α (ERα66), its ERα splice variants, and estrogen receptor-β (ERβ). Thus, we hypothesized that these splice variants may inhibit the glomerular enlargement that occurs early in type 1 diabetes (T1D). T1D was induced by streptozotocin (STZ) injection in 8- to 12-wk-old female mice lacking ERα66 (ERα66KO) or all ERα variants (αERKO), and their wild-type (WT) littermates. Basal renal ERα36 protein expression was reduced in the ERα66KO model and was downregulated by T1D in WT mice. T1D did not alter ERα46 or ERβ in WT-STZ; however, ERα46 was decreased modestly in ERα66KO mice. Renal hypertrophy was evident in all diabetic mice. F4/80-positive immunostaining was reduced in ERα66KO compared with WT and αERKO mice but was higher in STZ than in Control mice across all genotypes. Glomerular area was greater in WT and αERKO than in ERα66KO mice, with T1D-induced glomerular enlargement apparent in WT-STZ and αERKO-STZ, but not in ERα66KO-STZ mice. Proteinuria and hyperfiltration were evident in ERα66KO-STZ and αERKO-STZ, but not in WT-STZ mice. These data indicate that ERα splice variants may exert an inhibitory influence on glomerular enlargement and macrophage infiltration during T1D; however, effects of splice variants are masked in the presence of the full-length ERα66, suggesting that ERα66 acts in opposition to its splice variants to influence these parameters. In contrast, hyperfiltration and proteinuria in T1D are attenuated via an ERα66-dependent mechanism that is unaffected by splice variant status.

Deletion of pro-angiogenic factor vasohibin-2 ameliorates glomerular alterations in a mouse diabetic nephropathy model

Angiogenesis has been implicated in glomerular alterations in the early stage of diabetic nephropathy. We previously reported the renoprotective effects of vasohibin-1 (VASH1), which is a novel angiogenesis inhibitor derived from endothelial cells, on diabetic nephropathy progression. Vasohibin-2 (VASH2) was originally identified as a VASH1 homolog and possesses pro-angiogenic activity in contrast to VASH1. In addition, VASH2 was recently shown to promote epithelial-to-mesenchymal transition via enhanced transforming growth factor (TGF)-β signaling in cancer cells. Herein, we investigated the pathogenic roles of VASH2 in diabetic nephropathy using VAHS2-deficient mice. The type 1 diabetes model was induced by intraperitoneal injections of streptozotocin in VASH2 homozygous knockout (VASH2LacZ/LacZ) or wild-type mice. These mice were euthanized 16 weeks after inducing hyperglycemia. Increased urine albumin excretion and creatinine clearance observed in diabetic wild-type mice were significantly prevented in diabetic VASH2-deficient mice. Accordingly, diabetes-induced increase in glomerular volume and reduction in glomerular slit-diaphragm density were significantly improved in VASH2 knockout mice. Increased glomerular endothelial area was also suppressed in VASH2-deficient mice, in association with inhibition of enhanced vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2), but not VEGF level. Furthermore, glomerular accumulation of mesangial matrix, including type IV collagen, and increased expression of TGF-β were improved in diabetic VASH2 knockout mice compared with diabetic wild-type mice. Based on the immunofluorescence findings, endogenous VASH2 localization in glomeruli was consistent with mesangial cells. Human mesangial cells (HMCs) were cultured under high glucose condition in in vitro experiments. Transfection of VASH2 small interfering RNA (siRNA) into the HMCs resulted in the suppression of type IV collagen production induced by high glucose compared with control siRNA. These results indicate that VASH2 may be involved in diabetes-induced glomerular alterations, particularly impaired filtration barrier and mesangial expansion. Therefore, VASH2 is likely to represent a promising therapeutic target for diabetic nephropathy.

SIRT3 Activation Inhibits Development of Diabetic Kidney Disease

Diabetes continues to be the leading causes of kidney disease in the U.S. and around the world. Despite beneficial interventions implemented in patients with diabetes that mitigate some of its negative effects, kidney disease still progresses in most of these patients because the pathogenesis of diabetic kidney disease remains poorly understood. Recent evidence indicates that impairments in mitochondrial dynamics and function plays an important role in pathogenesis of diabetic kidney disease and brings promise to treatment strategies for improving mitochondrial function and the related pathways that may prevent or slow the progression of kidney disease.We aimed to test the influence of one key mitochondrial protein deacetylase, Sirtuin 3 (SIRT3) as a potential target for therapy in diabetic kidney disease. In kidney biopsies from human patients with diabetic nephropathy, there are decreases in SIRT3 mRNA and protein abundance in glomeruli and tubules. To test the effect of SIRT3 on the prevention of diabetic kidney disease, we conducted a study comparing three groups of mice: A control group, a diabetic group (db/db), and a diabetic group treated with nicotinamide riboside (NR), a precursor for NAD+, which is a co‐substrate required for SIRT3 activity. Treatment of diabetic mice with NR resulted in a) increase in renal SIRT3 activity as determined by significant decreases in total acetylated proteins and acetylated SOD2, significant decreases in b) albuminuria, c) mesangial expansion and glomerular area, d) accumulation of collagen IV protein, e) loss of synaptopodin and f) accumulation of 4‐HNE. In conclusion, SIRT3 plays an important role in diabetic kidney disease and increasing the SIRT3 activity may prevent the progression of diabetic kidney disease.Support or Funding InformationNIHThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.