MicroRNAs contribute to the pathogenesis of certain diseases and may serve as biomarkers. We analyzed glomerular microRNA expression in B6.MRLc1, which serve as a mouse model of autoimmune glomerulonephritis. We found that miR-26a was the most abundantly expressed microRNA in the glomerulus of normal C57BL/6 and that its glomerular expression in B6.MRLc1 was significantly lower than that in C57BL/6. In mouse kidneys, podocytes mainly expressed miR-26a, and glomerular miR-26a expression in B6.MRLc1 mice correlated negatively with the urinary albumin levels and podocyte-specific gene expression. Puromycin-induced injury of immortalized mouse podocytes decreased miR-26a expression, perturbed the actin cytoskeleton, and increased the release of exosomes containing miR-26a. Although miR-26a expression increased with differentiation of immortalized mouse podocytes, silencing miR-26a decreased the expression of genes associated with the podocyte differentiation and formation of the cytoskeleton. In particular, the levels of vimentin and actin significantly decreased. In patients with lupus nephritis and IgA nephropathy, glomerular miR-26a levels were significantly lower than those of healthy controls. In B6.MRLc1 and patients with lupus nephritis, miR-26a levels in urinary exosomes were significantly higher compared with those for the respective healthy control. These data indicate that miR-26a regulates podocyte differentiation and cytoskeletal integrity, and its altered levels in glomerulus and urine may serve as a marker of injured podocytes in autoimmune glomerulonephritis.

Indoxyl sulfate is a uremic toxin and a ligand of the aryl-hydrocarbon receptor (AhR), a transcriptional regulator. Elevated serum indoxyl sulfate levels may contribute to progressive kidney disease and associated vascular disease. We asked whether indoxyl sulfate injures podocytes in vivo and in vitro. Mice exposed to indoxyl sulfate for 8 w exhibited prominent tubulointerstitial lesions with vascular damage. Indoxyl sulfate-exposed mice with microalbuminuria showed ischemic changes, while more severely affected mice showed increased mesangial matrix, segmental solidification, and mesangiolysis. In normal mouse kidneys, AhR was predominantly localized to the podocyte nuclei. In mice exposed to indoxyl sulfate for 2 h, isolated glomeruli manifested increased Cyp1a1 expression, indicating AhR activation. After 8 w of indoxyl sulfate, podocytes showed foot process effacement, cytoplasmic vacuoles, and a focal granular and wrinkled pattern of podocin and synaptopodin expression. Furthermore, vimentin and AhR expression in the glomerulus was increased in the indoxyl sulfate-exposed glomeruli compared to controls. Glomerular expression of characteristic podocyte mRNAs was decreased, including Actn4, Cd2ap, Myh9, Nphs1, Nphs2, Podxl, Synpo, and Wt1. In vitro, immortalized-mouse podocytes exhibited AhR nuclear translocation beginning 30 min after 1 mM indoxyl sulfate exposure, and there was increased phospho-Rac1/Cdc42 at 2 h. After exposure to indoxyl sulfate for 24 h, mouse podocytes exhibited a pro-inflammatory phenotype, perturbed actin cytoskeleton, decreased expression of podocyte-specific genes, and decreased cell viability. In immortalized human podocytes, indoxyl sulfate treatment caused cell injury, decreased mRNA expression of podocyte-specific proteins, as well as integrins, collagens, cytoskeletal proteins, and bone morphogenetic proteins, and increased cytokine and chemokine expression. We propose that basal levels of AhR activity regulate podocyte function under normal conditions, and that increased activation of podocyte AhR by indoxyl sulfate contributes to progressive glomerular injury.

MicroRNAs act as post-transcriptional regulators, and urinary exosome (UExo)-derived microRNAs may be used as biomarkers. Herein, we screened for UExo-derived microRNAs reflecting kidney disease (KD) status in dogs. Examined dogs were divided into healthy kidney control (HC) and KD groups according to renal dysfunction. We confirmed the appearance of UExo having irregular globe-shapes in a dog by immunoblot detection of the exosome markers, TSG101 and CD9. Based on our previous data using KD model mice and the data obtained herein by next generation sequencing of UExo-derived microRNAs in dogs, miR-26a, miR-146a, miR-486, miR-21a, and miR-10a/b were selected as candidate microRNAs. In particular, UExo-derived miR-26a and miR-10a/b were significantly decreased in KD dogs, and miR-26a levels negatively correlated with deteriorated renal function compared to the other miRNAs. UExo-derived miR-21a levels corrected or not to that of internal control microRNAs in UExo, miR-26a and miR-191, significantly increased with renal dysfunction. In kidney tissues, the decrease of miR-26a and miR-10a/b in the glomerulus and miR-10b in the tubulointerstitium negatively correlated with deteriorated renal function and histopathology. Increased miR-21a in the tubulointerstitium rather than in the glomerulus correlated with deteriorated renal histopathology. In conclusion, microRNAs reflecting the changes in renal function and histopathology in dogs were identified in this study.

Members of the Toll-like receptor (TLR) family serve as pathogen sensors and participate in local autoimmune responses. This study found a correlation between glomerular injury and TLR expression by analysing BXSB/MpJ-Yaa (BXSB-Yaa) lupus model mice. In isolated glomeruli, the mRNA expression of several TLRs was higher in BXSB-Yaa mice than in healthy control BXSB mice. In particular, the expression of Tlr8 and its downstream cytokines was markedly increased. In mouse kidneys, TLR8 protein and mRNA localized to podocytes and TLR8 protein expression in the glomerulus was higher in BXSB-Yaa mice than in BXSB mice. In BXSB-Yaa mice, the glomerular levels of Tlr8 mRNA negatively correlated with the glomerular levels of podocyte functional markers (Nphs1, Nphs2, and Synpo) and positively correlated with urinary albumin levels. Furthermore, the glomerular and serum levels of miR-21, a putative microRNA ligand of TLR8, were higher in BXSB-Yaa mice than in BXSB mice. The urinary levels of Tlr8 mRNA were also higher in BXSB-Yaa mice than in BXSB mice. In conclusion, the overexpression of TLR8 correlates with the progression of podocyte injury in glomerulonephritis. Thus, altered levels of urinary Tlr8 mRNA might reflect podocyte injury.

Syrian golden hamsters (Mesocricetus auratus) are useful laboratory rodents for studying human infectious diseases, metabolic diseases and cancer. In other rodents, such as mice and rats, a mixture of medetomidine, midazolam and butorphanol functions as a useful anesthetic, although it alters some blood biochemical parameters. In this study, we examined the effects of this mixture on anesthesia and blood biochemical parameters, and the action of atipamezole, a medetomidine antagonist, in hamsters. Intramuscular injection of a mixture of medetomidine, midazolam and butorphanol at doses of 0.15, 2.0 and 2.5 mg/kg, respectively, had a short induction time (within 5 min) and produced an anesthetic duration of approximately 100 min in hamsters. We also demonstrated that 0.15 mg/kg of atipamezole, corresponding to the same dose as medetomidine, made hamsters recover quickly from anesthesia. The anesthetic agent markedly altered metabolic parameters, such as plasma glucose and insulin; however, 0.15 mg/kg of atipamezole returned these levels to normal range within approximately 10 min after the injection. The anesthetic also slightly altered mineral levels, such as plasma inorganic phosphorus, calcium and sodium; the latter two were also improved by atipamezole. Our results indicated that the mixture of medetomidine, midazolam, and butorphanol at doses of 0.15, 2.0 and 2.5 mg/kg, respectively, functioned as an effective anesthetic, and atipamezole was useful for antagonizing both anesthesia and biochemical alteration in hamsters.

The renal vasculature plays important roles in both homeostasis and pathology. In this study, we examined pathological changes in the renal microvascular in mouse models of kidney diseases. Glomerular lesions (GLs) in autoimmune disease-prone male BXSB/MpJ-Yaa (Yaa) mice and tubulointerstitial lesions (TILs) in male C57BL/6 mice subjected to unilateral ureteral obstruction (UUO) for 7 days were studied. Collected kidneys were examined using histopathological techniques. A nonparametric Mann–Whitney U test (P < 0.05) was performed to compare healthy controls and the experimental mice. The Kruskal-Wallis test was used to compare three or more groups, and multiple comparisons were performed using Scheffe’s method when significant differences were observed (P < 0.05). Yaa mice developed severe autoimmune glomerulonephritis, and the number of CD34+ glomerular capillaries decreased significantly in GLs compared to that in control mice. However, UUO-treated mice showed severe TILs only, and CD34+ tubulointerstitial capillaries were decreased significantly in TILs with the progression of tubulointerstitial fibrosis compared to those in untreated control kidneys. Infiltrations of B-cells, T-cells, and macrophages increased significantly in the respective lesions of both disease models (P < 0.05). In observations of vascular corrosion casts by scanning electron microscopy and of microfil rubber-perfused thick kidney sections by fluorescence microscopy, segmental absences of capillaries were observed in the GLs and TILs of Yaa and UUO-treated mice, respectively. Further, transmission electron microscopy revealed capillary endothelial injury in the respective lesions of both models. The numbers of CD34+ glomerular and tubulointerstitial capillaries were negatively correlated with all examined parameters in GLs (P < 0.05) and TILs (P < 0.01), respectively. From the analysis of mouse models, we identified inverse pathological correlations between the number of local capillaries in GLs and TILs and the severity of kidney diseases.