Nerve-evoked electrical activity regulates molecules and cells with immunological function in rat muscle tissue

Area of Science:

• Immunology
• Neuroscience
• Muscle Physiology

Background:

• Major histocompatibility complex (MHC) molecules are typically absent from skeletal muscle and central nervous system cells.
• Nerve activity is understood to influence muscle cell phenotype.

Purpose of the Study:

• To investigate the effect of muscle inactivity on MHC molecule expression in skeletal muscle.
• To explore the role of nerve activity in regulating MHC expression and interstitial immune cell presence.

Main Methods:

• Inducing skeletal muscle inactivity in rats via nerve impulse blockade.
• Quantifying MHC class I and class II molecule expression on muscle fibers and interstitial cells.
• Assessing the impact of direct electrical stimulation and denervation.
• Measuring interferon-gamma-like immunoreactivity.

Main Results:

• Muscle inactivity led to the expression of MHC class I molecules on muscle fibers.
• A threefold increase in MHC class II expressing cells within the muscle interstitium was observed after 2 weeks of impulse blockade.
• Denervation-induced changes were reversible with electrical stimulation.
• Interferon-gamma-like immunoreactivity accumulated in inactive muscle fibers.

Conclusions:

• Nerve-evoked muscle activity regulates MHC expression in skeletal muscle.
• Muscle inactivity promotes an increase in MHC expression and interstitial immune cell infiltration.
• Interferon-gamma or related cytokines may mediate the link between inactivity and MHC upregulation.
• These findings suggest that muscle inactivity can increase the immunoreactivity of muscle tissue.