Peripheral EphrinB1/EphB1 signalling attenuates muscle hyperalgesia in MPS patients and a rat model of taut band-associated persistent muscle pain

Preclinical efficacy of TZG in myofascial pain syndrome by impairing PI3K-RAC2 signaling-mediated neutrophil extracellular traps

Tianhe Zhuifeng Gao (TZG) shows a satisfying therapeutic efficacy in treating arthromyodynia, which shares similar etiology to myofascial pain syndrome (MPS). We herein aim to explore whether TZG could be a potential prescription for MPS therapy. An MPS rat model was successfully established presenting with reduced pain thresholds, abnormal local switch responses, etc., which was effectively reversed by TZG treatment externally. A transcriptome sequencing based on the active MTrPs samples of rats, combined with network analysis revealed that TZG might ameliorate the progression of MPS by impairing neutrophil extracellular traps (NETs) release through inhibiting PI3K-RAC2 signaling to reduce NADPH oxidase-originated ROS. Experimentally, the expression levels of inducers, biomarkers of NETs formation and vessel injury, and p-PI3K, p-P47, and RAC2 proteins were all significantly up-regulated in affected tissues, which were markedly reversed by TZG. Our results not only shed light into broadening the clinical indications of TZG, but benefit MPS therapy.

Dexmedetomidine inhibits abnormal muscle hypertrophy of myofascial trigger points via TNF-α/ NF-κB signaling pathway in rats

Myofascial pain syndrome (MPS) is a chronic pain disorder with inflammation-related primarily characterized by the presence of myofascial trigger points (MTrPs). Myocyte enhancer factor 2C (MEF2C) is involved in the occurrence of a variety of skeletal muscle diseases. However, it is not yet clear if MEF2C is involved in MTrPs. The purpose of this study was to investigate whether MEF2C was involved in the inflammatory pathogenesis of MTrPs. In the present study, we used RNA sequencing (RNA-seq) to compare the differential expression of myocyte enhancer factor 2C (MEF2C) in healthy participants and MTrPs participants. The widely used rat MTrPs model was established to research the upstream and downstream regulatory mechanism of MEF2C and found that MEF2C was significantly increased in patients with MTrPs. Dexmedetomidine (Dex) was injected intramuscularly in the MTrPs animal to assess its effects on MEF2C. The expression of MEF2C protein and mRNA in skeletal muscle of rats in the MTrPs group were up-regulated. In addition, the expression of TNF- α, p-P65, MLCK, and Myocilin (MyoC) was up-regulated and the mechanical pain threshold was decreased. Peripheral TNF- α injection significantly decreased the mechanical pain threshold and increased the expression of p-P65, MLCK, MEF2C, and MyoC in healthy rats. Maslinic acid increased the mechanical pain threshold and inhibited the expression of p-P65, MLCK, MEF2C, and MyoC. In addition, peripheral injection of DEX in MTrPs rats also inhibited the expression of TNF- α, p-P65, MLCK, MEF2C, and MyoC. These results suggest that MEF2C is involved in the inflammatory pathogenesis of MTrPs and DEX serves as a potential therapeutic strategy for the treatment of MPS.