[Effect of Xuebijing injection on endothelial microparticles and renal cortical microcirculation in septic rats]

To clarify the characteristics of renal cortical microcirculation and its relationship with the expression of plasma endothelial microparticle (EMP) in septic rats, and to evaluate the effect of Xuebijing injection as an adjuvant therapy of antibiotics on septic AKI.

The 8-10 weeks old specific pathogen free (SPF) male Sprague-Dawley (SD) rats were divided into sham operation group (Sham group), positive drug control group and Xuebijing group by the random number table method, with 10 rats in each group. The cecal ligation and puncture (CLP) with large ligation (ligated 75% of the cecum) was used to prepare a rat high-grade sepsis model; in the Sham group, the cecum was stretched without ligation or puncture. Due to the high mortality of CLP with large ligation, Xuebijing injection (4 mL/kg, 12 hours per time) and imipenem/cilastatin injection (90 mg/kg, 6 hours per time) were administered to the rats in the Xuebijing group via the tail vein immediately after the model was produced. Normal saline and imipenem/cilastatin were administered to the rats by the same methods in the positive drug control group. The rats in the Sham group were treated with the same volume of normal saline as any of the other two groups at the same frequency. At 48 hours after model reproduction, the mean arterial pressure (MAP) and blood lactic acid (Lac) of the rats were measured. The renal cortical microcirculation was monitored by using side stream dark-field imaging. Renal hypoxia signals were assessed by pimonidazole chloride immunohistochemistry. Plasma EMP levels were determined by using flow cytometry, and then the correlation between EMP and microcirculation parameters of renal cortex was analyzed. At the same time, the serum creatinine (SCr) was measured, and the renal injury score (Paller score) was used to evaluate the severity of renal tissue pathological damage.

Compared with the Sham group, perfused vessel density (PVD), microvascular flow index (MFI) and MAP in the positive drug control group and the Xuebijing group decreased significantly, the positive expression of hypoxia probe (pimonidazole) increased, Lac, EMP, Paller score and SCr increased significantly. However, compared with the positive drug control group, the renal cortical microcirculation in the Xuebijing group was improved significantly, PVD and MFI were increased significantly [PVD (mm/mm²): 16.20±1.20 vs. 9.77±1.12, MFI: 2.46±0.05 vs. 1.85±0.15, both P < 0.05], Lac was reduced significantly (mmol/L: 4.81±1.23 vs. 6.08±1.09, P < 0.05), MAP increased slightly [mmHg (1 mmHg = 0.133 kPa): 84.00±2.00 vs. 80.00±2.00, P > 0.05], suggested that Xuebijing injection improved renal microcirculation perfusion in septic rats, and this effect did not depend on the change of MAP. The positive expression of pemonidazole in renal cortex of the Xuebijing group was significantly lower than that of the positive drug control group [(35.89±1.13)% vs. (44.93±1.37) %, P < 0.05], suggested that Xuebijing injection alleviated renal hypoxia. The plasma EMP levels of rats in the Xuebijing group were significantly lower than those in the positive drug control group (×10⁶/L: 3.49±0.17 vs. 5.78±0.22, P < 0.05), and the EMP levels were significantly negatively correlated with PVD and MFI (r values were -0.94 and -0.95, respectively, both P < 0.05), indicated that the increase of plasma EMP was highly correlated with renal microcirculation disorder, and Xuebijing injection inhibited the increase of plasma EMP levels. The Paller score in the Xuebijing group was significantly lower than that in the positive drug control group (46.90±3.84 vs. 62.70±3.05, P < 0.05), and the level of SCr was also significantly lower than that in the positive drug control group (μmol/L: 121.1±12.4 vs. 192.7±23.9, P < 0.05), which suggested that Xuebijing injection relieved kidney injury and improved renal function in septic rats.

As an adjuvant therapy of antibiotics, Xuebijing injection could inhibit the expression of plasma EMP in rats with sepsis, improve renal cortex microcirculation, and reduce kidney injury.