Pericyte specific MDM2 knockout alleviates diabetic nephropathy inflammation in mice

Background: Diabetic nephropathy (DN), a major cause of mortality among diabetic patients, is one of the most common and severe microvascular complications of diabetes ([1]). DN is characterized by low-grade inflammation in the kidneys, marked by elevated expression of cell adhesion molecules, growth factors, chemokines, and pro-inflammatory cytokines ([2]). Murine double minute 2 (MDM2) is known to play diverse roles in inflammation ([3] [4] [5] [6] [7]). However, the role of MDM2 in pericytes in regulating inflammation during DN, as well as the underlying pathways involved, remains unclear. This study aimed to investigate the role of MDM2 in DN-related inflammation and to elucidate its associated pathways.

Methods: Pericyte-specific MDM2 knockout (MDM2-KO) mice were generated using the Cre-loxP system. Kidney tissue, blood, and urine samples were collected after three months of diabetes. Immunofluorescence, immunohistochemistry, Western blot, and PCR were employed to evaluate kidney function, injury, and inflammation across four groups of mice (wild-type nondiabetic control (WT-NC), wild-type diabetic control (WT-DC), pericyte MDM2-KO non diabetic control (KO-DC) and MDM2-KO diabetic animals (KO-DC)). The NF-κB signaling pathways, associated with inflammation and MDM2, were also analyzed.

Results: Improved kidney function was observed in MDM2-KO diabetic mice. Western blot revealed a significant increase in the pro-inflammatory cytokine IL-1 in the kidneys of WT-DC mice, which was suppressed in KO-DC mice. PCR analysis revealed elevated mRNA levels of several inflammatory cytokines, including IL-1, IL-6, TNF-α, and IL-17a, as well as chemokines such as CCL2, CCL3, and CXCL12, in WT-DC mice. These elevations were markedly inhibited in MDM2-deficient KO-DC mice. Furthermore, immunofluorescence analysis demonstrated a reduction in macrophage infiltration in the kidneys of diabetic MDM2-KO mice. Increased expression of NF-κB (p65), phosphorylated IκBα (P-IκBα), and nuclear translocation of p65 observed in WT-DC mice were significantly suppressed in KO-DC mice.

Conclusions: Pericyte-specific MDM2 knockout improves kidney function and significantly alleviates renal inflammation and immune cell infiltration in DN. MDM2 regulates kidney inflammation in DN through the NF-κB signaling pathways. Inhibition of MDM2 may offer potential therapeutic benefits for DN patients in clinical practice.

Acknowledgement: This study was funded by German Research Foundation (DFG)

Publication History

Article published online:
28 May 2025

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