Histamine H3 Receptor Signaling Regulates the NLRP3 Inflammasome Activation in C2C12 Myocyte During Myogenic Differentiation

NLRP3 inflammasome has been implicated in impaired post-injury muscle healing and in muscle atrophy. Histamine receptors play an important role in inflammation, but the role of histamine H-3 receptor (H3R) in myocyte regeneration and in the regulation of NLRP3 inflammasome is not known. We studied the effects of H3R signaling on C2C12 myocyte viability, apoptosis, and tumor necrosis factor alpha (TNF alpha)-induced NLRP3 inflammasome activation during striated myogenic differentiation at three time points (days 0, 3, and 6). Expression of Nlrp3, interleukin-1 beta (IL-1 beta), and myogenesis markers were determined. TNF alpha reduced overall viability of C2C12 cells, and exposure to TNF alpha induced apoptosis of cells at D6. Activation of H3R had no effect on viability or apoptosis, whereas inhibition of H3R increased TNF alpha-induced apoptosis. Stimulation of C2C12 cells with TNF alpha increased Nlrp3 mRNA expression at D3 and D6. Moreover, TNF alpha reduced the expression of myogenesis markers MyoD1, Myogenin, and Myosin-2 at D3 and D6. H3R attenuated TNF alpha-induced expression of Nlrp3 and further inhibited the myogenesis marker expression; while H3R -blockage enhanced the proinflammatory effects of TNF alpha and increased the myogenesis marker expression. TNF alpha-induced secretion of mature IL-1 beta was dependent on the activation of the NLRP3 inflammasome, as shown by the reduced secretion of mature IL-1 beta upon treatment of the cells with the small molecule inhibitor of the NLRP3 inflammasome (MCC950). The activation of H3R reduced TNF alpha-induced IL-1 beta secretion, while the H3R blockage had an opposite effect. In conclusion, the modulation of H3R activity regulates the effects of TNF alpha on C2C12 myocyte differentiation and TNF alpha-induced activation of NLRP3 inflammasome. Thus, H3R signaling may represent a novel target for limiting postinjury muscle inflammation and muscle atrophy.

Automated summary

The study found that H3R signaling pathway regulates the effects of TNF-α on C2C12 myocyte differentiation and activation of NLRP3 inflammasome. By modulating H3R activity, muscle inflammation and atrophy can be limited.