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Leucine-rich repeat kinase 2 (LRRK2) is a known regulator of autophagy in a range of cell types. Here, we investigated the role of LRRK2-associated autophagy during acute kidney injury (AKI) and its underlying mechanism(s) of action. Male mice aged 8-weeks were treated with the LRRK2 inhibitor MLi-2 and exposed to lipopolysaccharide (LPS) through intraperitoneal injection or ischemia-reperfusion (IR) surgery. Mice were sacrificed 12 or 24 h post-LPS injection or IR operation and blood was collected for serum creatinine measurements. Kidney cortical tissues were collected for western blot analysis of podocyte-specific markers and autophagy-associated proteins. Renal histopathology was observed through hematoxylin-eosin staining. For cell-based assays, immortalized mouse podocytes were silenced for LRRK2 through siRNA transfection and exposed to LPS or cobalt chloride. Changes in cell viability were investigated using cell counting kit-8, flow cytometry and MTT assays. Expression of podocyte-specific markers and autophagy-associated proteins were analyzed by western blotting. We observed an increase in LRRK2 expression at 12 h post-LPS injection and IR surgery that was accompanied by enhanced autophagy. At 24 h post-treatment, both LRRK2 expression and autophagy declined. Kidney injury was most pronounced in mice treated with MLi-2. Podocytes silenced for LRRK2 showed a loss of cell viability, decreased levels of podocyte-specific protein expression and a suppression of autophagy. Together, these data reveal the protective effects of LRRK2 during AKI through enhanced podocyte autophagy and cell viability., (© 2022 Wiley Periodicals LLC.)

Objective: To explore the protective effects of leflunomide (A771726) on the expression of podocalyxin, NF-κB and matrix metalloproteinase-9 (MMP-9) in podocytes exposed to high glucose environment and elucidate its mechanism., Methods: Podocytes were cultured in high glucose. And the altered expressions of podocyte protein podocalyxin were detected by Western blotting at different timepoints. Then podocytes were divided into 4 groups of normal glucose control, leflunomide, high glucose and hypertonic control. The expression level of podocalyxin protein in each group was detected by Western blotting. And NF-κB p65 and phosphorylation of NF-κB p65 (P-NF-κBp65) in podocytes cultured in high glucose were detected at different timepoints. And then the podocytes were divided into 5 groups of normal glucose, mannitol, hypertonic control, high glucose, leflunomide and PDTC (NF-κB blocker). And the expressions of MMP-9 protein in these groups were also detected by Western blotting., Results: In the high glucose environment, the expression of podocalyxin declined instantly. Compared with the high-glucose group, the podocalyxin expression of the leflunomide group was significantly higher than the high glucose group (0.46 ± 0.04 vs 0.13 ± 0.03, P < 0.05). After 30-minute stimulation by high glucose, the activation of NF-κB started and the expression of P-NF-κBp65 protein increased. Such activities peaked at 60 minutes and reverted to a basic level after 6 hours. Compared with the high glucose group, the expressions of MMP-9 in PDTC and leflunomide groups were significantly lower than the high glucose group. And the differences were statistically significant (0.71 ± 0.01, 0.64 ± 0.03 vs 1.64 ± 0.03, both P < 0.05)., Conclusions: Leflunomide has protective effects on podocytes in high glucose. And its mechanism is possibly due to a lowered expression of MMP-9 through an inhibition of NF-κB activation.

Objective: To explore the effects of leflunomide active metabolite A771726 on high glucose-induced podocyte cytoskeleton and its possible signaling pathway., Methods: The conditionally immortal human glomerular podocytes were divided into normal glucose (NG), mannitol (MA), high glucose (HG), high glucose with PDTC (pyrrolidine dithiocarbamate, a NF-κBp65 inhibitor) and high glucose with active leflunomide metabolite A771726 groups. Western blot was used to measure the ratio of p-NF-κBp65 to total NF-κBp65. And the protein and mRNA expressions of NF-κBp65, TRPC6 and nephrin were detected by Western blot and reverse transcription polymerase chain reaction (PCR). Immunofluorescence staining was used to detect the changes in the skeleton of podocyte., Results: (1) Podocytes with high glucose could activate the NF-κBp65 signaling pathway. There was a significant increase of p-NF-κBp65 protein at 60 min versus 0 min (1.20 ± 0.04 vs 0.79 ± 0.02, P < 0.01). Little activation of the pathways was observed in groups NG and MA. The up-regulated protein expression of p-NF-κBp65 induced with high glucose was significantly inhibited by PDTC and A771726 (both P < 0.05). The difference of NF-κBp65 mRNA expression was not statistically significant between the groups (all P > 0.05). (2) High glucose-induced podocyte activated the NF-κBp65 signaling path. Its downstream TRPC6 mRNA and protein expression significantly increased than NG while nephrin became down-regulated more than NG. PDTC and A771726 inhibited the high expression of TRPC6 while the expression of nephrin was elevated (all P < 0.05). (3) Immunofluorescent assay of high glucose-induced podocyte cytoskeleton showed disorderly F-actin and a disappearance of tensile fiber after 72 h., Conclusion: Active leflunomide metabolite A771726 may protect podocytes through blocking the high glucose-induced signaling pathway of NF-κBp65.

Objective: To explore the therapeutic effects of leflunomide metabolite A771726 on high glucose-induced podocyte injury and understand its mechanism., Methods: The conditionally immortal human glomerular podocytes were divided into normal glucose group (NG), high glucose group (HG), mannitol group (MA), high glucose with SB202190 (a p38MAPK inhibitor) group and high glucose with active leflunomide metabolite A771726 group. The levels of p38MAPK and p-p38 protein were determined by Western blot. And the rate of podocyte apoptosis was evaluated by flow cytometry., Results: (1) Podocytes with high glucose could activate the p38MAPK signaling pathway. The p-p38 protein expression was significantly elevated. Little activation of the pathways was observed in Groups NG and MA. As compared to HG, the p-p38 protein expression was significantly lowered in SB202190 and A771726 groups. (2) Apoptosis increased in podocytes with high glucose after 24 h. The apoptotic rate of group HG was the most dramatic at 48 h (18.6 ± 0.7)%. It was significantly higher than those of Groups NG and MA. The group of high glucose with SB202190 and high glucose with active leflunomide metabolite A771726 could reduce the podocyte apoptosis by 26% and 17% respectively versus the HG group. And the difference was statistically significant., Conclusion: Leflunomide can inhibit high glucose-induced podocyte apoptosis. And this effect may be involved in its inhibition of activation of p38MAPK.