Mechanism of Huangwu Ganfu Ointment in Treatment of Peripheral Inflammatory Hyperalgesia of Knee Osteoarthritis Based on TRPV1 / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the regulatory effect of Huangwu Ganfu ointment on transient receptor potential anchor protein 1 （TRPV1） receptor expression， macrophage polarization， and p38 mitogen-activated protein kinase （p38 MAPK） signaling pathway in synovial tissue of knee osteoarthritis （KOA） rats with yang deficiency and cold coagulation syndrome and explore the mechanism of relieving peripheral inflammatory hyperalgesia of KOA. MethodForty-eight male SD rats were randomly divided into blank group， model group， high-dose， middle-dose， and low-dose groups of Huangwu Ganfu ointment （9.3， 4.65， 2.325 g·kg-1）， and celecoxib group （20.82 mg·kg-1）. The KOA rat model of yang deficiency and cold coagulation syndrome was established through climate box and swimming for two weeks combined with an injection of sodium iodoacetate （MIA） in the articular cavity. After continuous administration for four weeks， the general condition of rats in each group was observed， and the pain withdrawal threshold （PWT） and joint diameter induced by mechanical stimulation were recorded. The expression levels of interleukin-1β （IL-1β）， tumor necrosis factor-α （TNF-α）， nerve growth factor （NGF）， and calcitonin gene-related peptide （CGRP） inflammatory factor were detected by enzyme-linked immunosorbent assay （ELISA）， and the histopathological changes of synovial tissue of the knee joint were observed by hematoxylin-eosin （HE） staining. Western blot was used to detect the protein expression of TRPV1， p38 MAPK， and p-p38 MAPK in synovial tissue of the knee joint， and immunofluorescence （IF） was used to evaluate the polarization of M1/M2 macrophages. ResultCompared with that in the blank group， the overall mental state of the model group was worse， and the autonomous activity was decreased. The body mass was lower， and the joint diameter was increased. The X-ray showed that the osteophyte at the edge of the joint proliferated， and the articular surface was obviously rough. The articular cavity was significantly narrowed， and the PWT was significantly decreased （P<0.01）. The contents of IL-1β， TNF-α， CGRP， and NGF in serum and synovium Krenn score increased significantly （P<0.01）. The protein expression of TRPV1 and p-p38 MAPK/p38 MAPK increased significantly （P<0.01）， and the proportion of M1 macrophages and M1/M2 increased （P<0.01）， while the proportion of M2 macrophages decreased （P<0.01）. Compared with model group， the body mass in the low， middle， and high dose groups of Huangwu Ganfu ointment increased to different degrees （P<0.05， P<0.01）. The diameter of the knee joint in the high dose group of Huangwu Ganfu ointment and celecoxib group decreased （P<0.01）. The recovery of PWT in the high and middle dose groups of Huangwu Ganfu ointment groups was more obvious （P<0.05）. The contents of IL-1β and CGRP in the serum of rats in each administration group were significantly decreased （P<0.01）， and the content of serum TNF-α in the celecoxib group and high dose group of Huangwu Ganfu ointment decreased significantly （P<0.05）. The content of serum NGF in the middle dose group of Huangwu Ganfu ointment decreased significantly （P<0.05）， and the synovium Krenn score decreased in the high dose group of Huangwu Ganfu ointment （P<0.05）. In addition， the protein expression of TRPV1 and p-p38 MAPK/p38 MAPK in synovial tissue decreased significantly in all groups of Huangwu Ganfu ointment （P<0.01）. The proportion of M1 macrophages in synovial tissue in the celecoxib group and all groups of Huangwu Ganfu ointment decreased （P<0.01）， and the proportion of M2 macrophages in the high dose group of Huangwu Ganfu ointment increased （P<0.05）. The M1/M2 in the middle and high dose groups of Huangwu Ganfu ointment decreased （P<0.05）. ConclusionHuangwu Ganfu ointment can mediate the polarization of macrophages to reduce the inflammatory reaction of KOA， alleviate the release of inflammatory pain mediators， and lower the protein expression of TRPV1. The mechanism may be related to the p38 MAPK signaling pathway， so as to improve the peripheral hyperalgesia of KOA.