Protective effects of quercetin treatment in a pristane-induced mouse model of lupus nephritis.

INTRODUCTION: Lupus nephritis (LN) is one of the most severe complications of systemic lupus erythematosus. As murine models of LN are valuable tools to better understand its pathophysiology and to search for new effective treatments, we investigated the effects of the bioflavonoid quercetin on pristane-induced LN mice through histomorphological analyses. METHODS: Immunofluorescence and biochemical assays were used to evaluate the expression of markers of inflammation (interleukin-6, IL-6; tumour necrosis factor-α, TNF-α), oxidative stress (catalase, CAT; superoxide dismutase 1, SOD1; thiobarbituric acid reactive substances, TBARS), apoptosis (Bax), and fibrosis (transforming growth factor-ß1, TGF-ß1). Glomerular and tubular ultrastructure was analysed, and tissue messenger RNA of podocin, podoplanin and α3ß1-integrin were quantified using the real-time polymerase chain reaction. RESULTS: Pristane-induced LN mice showed severe kidney injury, characterized by increased proteinuria, glomerular mesangial expansion and inflammation, high expression of the pro-fibrotic, apoptotic and prooxidant markers and reduction of antioxidants. In the kidney ultrastructure, foot process (FP) effacement, apoptotic mesangial cells and abnormal mitochondria with disrupted cristae were observed, along with suppressed tissue mRNA of podocin, podoplanin and α3ß1-integrin. Treatment with quercetin in the pristane-induced LN mice model was nephroprotective, decreasing proteinuria levels and significantly lowering tissue expression of IL-6, TNF-α, TGF-ß1, Bax and TBARS. Simultaneously, quercetin significantly increased CAT and SOD1 expressions in these mice. In addition, it was observed improvement of the kidney ultrastructure, and tissue mRNA of podocin, but not podoplanin and α3ß1-integrin, was restored to the levels found in the control mice. CONCLUSION: In conclusion, these findings provide experimental evidence of the renoprotective effects of quercetin in the pristane-induced LN mice model. We suggest that quercetin effectively ameliorates the kidney damage caused by pristane, a bioflavonoid to be further evaluated as a new therapeutic strategy in this disease.

Unraveling the podocyte injury in lupus nephritis: Clinical and experimental approaches.

OBJECTIVES: Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease with renal involvement in over half of the cases. In lupus nephritis (LN), podocytes are injured at the structural and molecular level. Spontaneous or induced animal models of SLE can reproduce the glomerular damage, similar to what is observed in humans. In this review, murine models focusing the podocyte injury were summarized, and therapeutic strategies to protect the podocyte cell were explored. METHODS: Using the PubMed and MEDLINE databases from 1950 to 2015, literature search was conducted by article title and abstract, combining the following key words: "systemic lupus erythematosus," "lupus nephritis," "animal model," "podocyte injury," and "treatment." RESULTS: Published or in-press eligible studies that were published as full-length articles in English-language journals were considered. Articles were summarized according to podocyte structure and function, the podocyte injury resulting from spontaneous (NZB/W F1 hybrid, MRL/lpr, and BXSB-Yaa mice) or induced (chronic graft-versus-host disease and pristane) mice models of LN, and the protective effects of drug treatments on podocyte cell structure and function reported in these models. CONCLUSIONS: Murine models of SLE have proven useful for better comprehension of the multiple mechanisms involved in systemic autoimmunity that leads to LN. These critical tools should be considered when target therapies are designed to control this disorder.