The mechanism by which naringin regulates extracellular matrix expression, inflammatory response, and apoptosis in myeloid cells
LIN Fei,LI Hen,HU Tian-yi
Abstract:
Objective To investigate the protective effect of naringin on lipopolysaccharide (LPS)-induced degenerated nucleus pulposus(NP) cells and its molecular mechanism, and to provide a theoretical basis for the development of novel therapeutic strategies for intervertebral disc degeneration (IVDD). Methods Model of LPS-induced degenerated NP cells was constructed, and different concentrations (10-40 μmol/L) of naringin were applied to the degenerated NP cells for intervention treatments, Western Blot and other techniques were used to detect extracellular matrix (ECM) proteins [e.g. Collagen II, Aggrecan, matrix metalloproteinase-3(MMP-3), MMP-13], inflammatory factors [e.g. tumor necrosis factor-α(TNF-α), Interleukin-6 (IL-6)], apoptosis-related factors [B cell lymphoma-2(Bcl-2), Caspase-2], and expression of mitogen-activated protein kinase (MAPK) signalling pathway-related proteins [(mitogen-activated extracellular signal-regulated kinase, MEK), extracellular regulated protein kinases (ERK), P38]. In addition, P38 protein expression was knocked down by transfection of P38 small interfering RNA (siRNA) to further investigate the role of P38 in IVDD. Results LPS treatment significantly down-regulated the expression of Collagen II and Aggrecan, up-regulated the activities of MMP-3 and MMP-13, induced the secretion of TNF-α and IL-6, and promoted apoptosis, and enhanced the expression of MEK, ERK, and P38 proteins in the MAPK signalling pathway. Naringin intervention dose-dependently reversed the above pathological changes, up-regulated the expression of Collagen II and Aggrecan, down-regulated the activities of MMP-3 and MMP-13, decreased the levels of TNF-α and IL-6, reduced apoptosis, and inhibited the expression of MEK, ERK and P38 proteins. In the group transfected with P38 siRNA, the expression of P38 proteins was reduced, the expression of proteins related to ECM synthesis was up-regulated, and the expression of inflammation-related proteins was increased. In the P38 siRNA transfected group, P38 protein expression was reduced, ECM synthesis-related protein expression was up-regulated, and the level of inflammatory factors decreased significantly. Conclusion Naringin can regulate IVDD by targeting the P38 MAPK pathway and inhibit ECM degradation, inflammation and apoptosis in degenerated NP cells, which provides a new potential target and therapeutic strategy for the treatment of IVDD.
