Xuebijing injection and its bioactive components alleviate nephrotic syndrome by inhibiting podocyte inflammatory injury

Xuebijing injection (XBJ) is widely used to treat nephrotic syndrome (NS) in clinic, but its bioactive components and therapeutic mechanism are still unclear. In this study, the bioactive components of XBJ were determined by ultra-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS). The therapeutic effect of XBJ on NS was evaluated in BALB/c mice induced by adriamycin (ADR, 10 mg/kg) via a single tail vein. The protective effect of XBJ and its bioactive components on podocytes was demonstrated using mouse podocytes (MPC-5) induced by lipopolysaccharide (LPS, 4 μg/mL). The results show that 33 components of XBJ were identified. Furthermore, 12 bioactive components were detected in blood, including protocatechuic acid, salvianolic acid C, benzoyloxypaeoniflorin, danshensu, salvianolic acid A, salvianolic acid B, catechin, caffeic acid, galloylpaeoniflorin, oxypaeoniflorin, hydroxysafflor yellow A, rosmarinic acid. The relative content (%) of the bioactive components were 59.32, 16.01, 9.97, 9.73, 8.72, 8.31, 7.92, 6.54, 1.54, 1.30, 0.68 and 0.59 in this order. After XBJ treatment, the renal function, hyperlipidemia and renal pathological damage were improved in NS model mice. Moreover, the levels of nephrin and desmin which are functional proteins in podocytes were reversed, and the levels of pro-inflammatory factors were reduced by XBJ. Interestingly, protocatechuic acid and salvianolic acid C also showed good protective effects on podocyte function and reduced the level of inflammation in LPS-induced MPC-5. The study is the first time to elucidate the bioactive components of XBJ and its potential therapeutic mechanism for treating NS by protecting podocyte function.