Cyclosporine A blocks autophagic flux in tubular epithelial cells by impairing TFEB-mediated lysosomal function.

Cyclosporine A (CsA) is an immunosuppressor widely used for the prevention of acute rejection during solid organ transplantation. However, severe nephrotoxicity has substantially limited its long-term usage. Recently, an impaired autophagy pathway was suggested to be involved in the pathogenesis of chronic CsA nephrotoxicity. However, the underlying mechanisms of CsA-induced autophagy blockade in tubular cells remain unclear. In the present study, we observed that CsA suppressed the activation and expression of transcription factor EB (TFEB) by increasing the activation of mTOR, in turn promoting lysosomal dysfunction and autophagy flux blockade in tubular epithelial cells (TECs) in vivo and in vitro. Restoration of TFEB activation by Torin1-mediated mTOR inhibition significantly improved lysosomal function and rescued autophagy pathway activity, suppressing TEC injury. In summary, targeting TFEB-mediated autophagy flux represents a potential therapeutic strategy for CsA-induced nephrotoxicity.

Accelerated Glomerular Cell Senescence in Experimental Lupus Nephritis.

BACKGROUND The aim of this study was to determine whether senescence in renal glomeruli is involved in lupus nephritis (LN); the expression of senescence-associated ß-galactosidase (SA-ß-Gal) and its association with glomerular lesions were investigated in a mouse model of LN. MATERIAL AND METHODS Eighteen MRL/lpr mice with severe proteinuria were randomly divided into 2 equal groups and intraperitoneally injected with dexamethasone (DEX) or saline; 4 age-matched mice with mild proteinuria served as controls. Serum creatinine and urinary protein levels were analyzed, and kidney histological changes were observed by periodic acid-Schiff and Sirius Red staining. SA-ß-Gal was detected via histochemistry. Glomerular expression of collagen IV, α-SMA, and nephrin was analyzed by immunohistochemistry, and glomerular complement C3 deposition was tested by immunofluorescence. The relationships between SA-ß-Gal expression and renal function or glomerular lesion markers were determined by Spearman's correlation analysis. RESULTS Mice with severe proteinuria exhibited glomerular segmental sclerosis and endothelial cell proliferation. DEX administration suppressed these lesions but had no significant effect on 24-hour urinary protein levels. The elevated glomerular expression of SA-ß-Gal in proteinuric mice was attenuated by DEX treatment. In addition, DEX treatment markedly downregulated glomerular C3 deposition and collagen IV and α-SMA expression, while significantly increasing nephrin expression. Furthermore, SA-ß-Gal expression was positively correlated with urinary protein levels and expression of α-SMA. CONCLUSIONS Accelerated senescence of glomerular cells may contribute to glomerular injury in LN.

Hydroxychloroquine administration exacerbates acute kidney injury complicated by lupus nephritis.

BACKGROUND: Hydroxychloroquine (HCQ) has been recommended as a basic treatment for lupus nephritis (LN) during this decade based on its ability to improve LN-related renal immune-mediated inflammatory lesions. As a classical lysosomal inhibitor, HCQ may inhibit lysosomal degradation and disrupt protective autophagy in proximal tubular epithelial cells (PTECs). Therefore, the final renal effects of HCQ on LN need to be clarified. METHOD: HCQ was administered on spontaneous female MRL/lpr LN mice with severe proteinuria daily for 4 weeks. Moreover, the MRL/lpr mice with proteinuric LN were subjected to cisplatin-induced or unilateral ischemia/reperfusion (I/R)-induced acute kidney injury (AKI) after 2 weeks of HCQ preadministration. RESULTS: As expected, HCQ treatment increased the survival ratio and downregulated the levels of serum creatinine in the mice with LN, ameliorated renal lesions, and inhibited renal interstitial inflammation. Unexpectedly, HCQ preadministration significantly increased susceptibility to and delayed the recovery of AKI complicated by LN, as demonstrated by an increase in PTEC apoptosis and expression of the tubular injury marker KIM-1 as well as the retardation of PTEC replenishment. HCQ preadministration suppressed the proliferation of PTECs by arresting cells in G1/S phase and upregulated the expression of cell cycle inhibitors. Furthermore, HCQ preadministration disrupted the PTEC autophagy-lysosomal pathway and accelerated PTEC senescence. CONCLUSION: HCQ treatment may increase susceptibility and delay the recovery of AKI complicated by LN despite its ability to improve LN-related renal immune-mediated inflammatory lesions. The probable mechanism involves accelerated apoptosis and inhibited proliferation of PTECs via autophagy-lysosomal pathway disruption and senescence promotion.

Asiatic acid protects against cisplatin-induced acute kidney injury via anti-apoptosis and anti-inflammation.

Cisplatin is a well-known chemotherapeutic drug applied for the treatment of numerous human cancers. However, the use of cisplatin in clinic is limited by certain serious side effects, such as nephrotoxicity. Unfortunately, there is currently no effective therapeutic approach to prevent cisplatin-induced AKI. Increasing evidence suggests that apoptosis of tubular epithelial cells and renal inflammation mainly determine the progression and outcome of cisplatin-induced AKI. Asiatic acid (AA) has been reported have the functions of anti-inflammation and anti-apoptosis, etc. But the effects of AA on kidney injury induced by cisplatin are still not known. The current study aimed to determine the potential renoprotective effects of AA on kidney injury induced by cisplatin. Twenty-four C57BL/6 male mice were randomly divided into four groups: normal control (CON), cisplatin-induced AKI (CIS), AKI with 50 mg/kg AA pretreatment (CIS + AA50), and AKI with 100 mg/kg AA pretreatment (CIS + AA100). Mice were anesthetized and sacrificed at 72 h after the cisplatin injection. Blood and kidney samples were collected for analyses. Compared with CON mice, cisplatin-treated mice exhibited severe tubular necrosis and elevated serum creatinine level. However, AA pretreatment (50 mg/kg or 100 mg/kg) markedly suppressed the elevated serum creatinine, blood urea nitrogen and histological changes. Moreover, AA pretreatment notably downregulated tubular expression of kidney injury molecule-1 (KIM-1) and the number of apoptotic cells, and upregulated the expression of the apoptosis inhibitor survivin and promoted tubular proliferation as evidenced by an increase in the number of proliferating cell nuclear antigen-positive cells. In addition, AA suppressed the enhanced mRNA expression of proinflammatory cytokines IL-1ß, TNF-α, MCP-1 and caspase-1 in the kidneys. Furthermore, AA pretreatment inhibited NF-κB activation and the inflammatory response, which may result from Smad7 up-regulation. In conclusion, AA protects against cisplatin-induced AKI via anti-apoptosis and anti-inflammation.