Ulinastatin Improves Renal Microcirculation by Protecting Endothelial Cells and Inhibiting Autophagy in a Septic Rat Model

Introduction: Increased permeability of the renal capillaries is a common consequence of sepsis-associated acute kidney injury. Vascular endothelial (VE)-cadherin is a strictly endothelial-specific adhesion molecule that can control the permeability of the blood vessel wall. Additionally, autophagy plays an important role in maintaining cell stability. Ulinastatin, a urinary trypsin inhibitor, attenuates the systemic inflammatory response and visceral vasopermeability. However, it is uncertain whether ulinastatin can improve renal microcirculation by acting on the endothelial adhesion junction. Methods: We observed the effect of ulinastatin in a septic rat model using contrast-enhanced ultrasonography (CEUS) to evaluate the perfusion of the renal cortex and medulla. Male adult Sprague Dawley rats were subjected to cecal ligation and puncture and divided into the sham, sepsis, and ulinastatin groups. Ulinastatin (50,000 U/kg) was injected into the tail vein immediately after the operation. The CEUS was performed to evaluate the renal microcirculation perfusion at 3, 6, 12, and 24 h after the operation. Histological staining was used to evaluate kidney injury scores. Western blot was used to quantify the expression of VE-cadherin, LC3II, and inflammatory factors (interleukin-1β, interleukin-6, and tumor necrosis factor-α) in kidney tissue, and enzyme-linked immunosorbent assay detected serum inflammatory factors and kidney function and early kidney injury biomarker levels. Results: Compared with the sham group, ulinastatin reduced the inflammatory response, inhibited autophagy, maintained the expression of VE-cadherin, and meliorated cortical and medullary perfusion. Conclusion: Ulinastatin effectively protects the adhesion junction and helps ameliorate the perfusion of kidney capillaries during sepsis by the inhibition of autophagy and the expression of inflammatory factors.