Ulinastatin ameliorates acute kidney injury induced by crush syndrome inflammation by modulating Th17/Treg cells

Background: Acute kidney injury (AKI) is the main complication of crush syndrome (CS), and it is also a cause of lethality in CS. However, effective treatments for AKI are still lacking. Ulinastatin (UTI) is a broad-spectrum serine protease inhibitor extracted from human urine that reportedly modulates innate immunity and pro-inflammatory responses in sepsis. Here, we explored the effect and the potential mechanism of ulinastatin on crush syndrome-induced acute kidney injury (CSAKI). Methods: A CSAKI rat model was established by using a digital crush injury device platform. Forty-six male Wistar rats were randomly divided into five groups: the normal control (n = 6), CSAKI model (n = 10), CSAKI plus UTI1 (50,000 U/kg) (n = 10), CSAKI plus UTI2 (100,000 U/kg) (n = 10) and CSAKI plus UTI3 (200,000 U/ kg) (n = 10) groups. Hematoxylin-eosin (HE) staining was used to investigate the reliability of the CSAKI model. The percentage of Th17/Treg lymphocytes in peripheral blood was measured by flow cytometry, and the expression of transcription factors associated with Th17/Treg cells was evaluated by quantitative real-time polymerase chain reaction (PCR). In addition, specific cytokines released by Th17/Treg cells in serum and kidney tissues were detected by enzyme-linked immunosorbent assay (ELISA). Results: Treatment with ulinastatin could significantly decrease serum BUN, CK, Scr, Mb and K+ levels compared with CSAKI group. HE staining results showed that ulinastatin could inhibit inflammatory cells infiltration, decrease sarcomere rupture in muscle tissues induced by extrusion, and alleviate the glomerular congestion and edema, as well as decrease myoglobin cast in kidney tissues. The proportion of CD4(+) CD25(+) Foxp3(+) regulatory T (Treg) cells and Foxp3 expression levels were decreased in the CSAKI animals, while IL-17 expression levels were significantly increased, compared with those of the normal control group. Treatment with ulinastatin upregulated the proportion of Treg cells in CD4(+) T cells and downregulated the expression of IL-17 compared with those of the CSAKI group. Conclusion: The findings of our study indicate that UTI attenuates CS-induced AKI and alleviate the inflammatory response during the early stage. The mechanism of UTI may be due to regulating the balance between Th17/Treg cells. Our study provides a new mechanism for the beneficial effect of ulinastatin on CSAKI.