The Inhibitory Effects of Pentacyclic Triterpenes from Loquat Leaf against Th17 Differentiation

Loquat leaf is an herb that is commonly used in traditional Chinese medicine (TCM) for its anti-inflammatory properties. Numerous studies have demonstrated that Th17 cells play a fundamental role in mediating SLE pathological deterioration. In our study, we investigated the inhibitory effect of pentacyclic triterpenes from loquat leaf on T helper 17 (Th17) cells and the therapeutic efficacy of OA in Lupus nephritis (LN) development.

We isolated three pentacyclic triterpene compounds rom loquat leaf by bioassay-directed fractionation and separation method. There were methyl corosolate (MC), uvaol (UL), and oleanolic acid (OA) Firstly, we elucidated Retinoic acid receptor-related orphan receptor gamma t (RORγt) inhibitory activity of these three compounds in the cell-based assay and Th17 differentiation in vitro assay. Then, we used OA-treated pristine-induced LN mice to evaluate the therapeutic effects of OA in LN development. Anti-dsDNA level in serum was detected by enzyme-linked immunosorbent assay (ELISA), interleukin 17A (IL-17A) and interferon-γ (IFN-γ) expression in spleen cells by Flow cytometry (FCM), histomorphologic examination of kidneys were performed by periodic acid schiff (PAS) staining and immunofluorescence analysis.

Pentacyclic triterpene compounds (MC, UL, OA) displayed inhibition of RORγt activity in cell-based assay and Th17 differentiation in vitro. Furthermore, our results also showed that OA could significantly decrease serum anti-dsDNA antibody levels, IL-17A and IFN-γ expression and alleviate renal pathological damage in OA-treated group mice than in the model group mice.

These results demonstrated that OA can improve the clinical manifestation of LN, indicating potential application in SLE therapy.