title: Regenerative function of immune system: Modulation of muscle stem cells.
abstract: Ageing is characterised by progressive deterioration of physiological systems and the loss of skeletal muscle mass is one of the most recognisable, leading to muscle weakness and mobility impairments. This review highlights interactions between the immune system and skeletal muscle stem cells (widely termed satellite cells or myoblasts) to influence satellite cell behaviour during muscle regeneration after injury, and outlines deficits associated with ageing. Resident neutrophils and macrophages in skeletal muscle become activated when muscle fibres are damaged via stimuli (e.g. contusions, strains, avulsions, hyperextensions, ruptures) and release high concentrations of cytokines, chemokines and growth factors into the microenvironment. These localised responses serve to attract additional immune cells which can reach in excess of 1×10(5) immune cell/mm(3) of skeletal muscle in order to orchestrate the repair process. T-cells have a delayed response, reaching peak activation roughly 4 days after the initial damage. The cytokines and growth factors released by activated T-cells play a key role in muscle satellite cell proliferation and migration, although the precise mechanisms of these interactions remain unclear. T-cells in older people display limited ability to activate satellite cell proliferation and migration which is likely to contribute to insufficient muscle repair and, consequently, muscle wasting and weakness. If the factors released by T-cells to activate satellite cells can be identified, it may be possible to develop therapeutic agents to enhance muscle regeneration and reduce the impact of muscle wasting during ageing and disease.
authors.affiliation: Healthcare Science Research Institute, School of Healthcare Science Manchester Metropolitan University, John Dalton Building, Chester Street, M1 5GD Manchester, UK.
authors.forename: Jasdeep
authors.initials: J
authors.lastname: Saini
authors.affiliation: Healthcare Science Research Institute, School of Healthcare Science Manchester Metropolitan University, John Dalton Building, Chester Street, M1 5GD Manchester, UK.
authors.forename: Jamie S
authors.initials: JS
authors.lastname: McPhee
authors.affiliation: Healthcare Science Research Institute, School of Healthcare Science Manchester Metropolitan University, John Dalton Building, Chester Street, M1 5GD Manchester, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Al-Dabbagh
authors.affiliation: Research Institute for Sport & Exercise Sciences, School of Sport and Exercise Sciences, Tom Reilly Building, Byrom Street Campus, Liverpool John Moores University, Liverpool L3 3AF, UK.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Stewart
authors.affiliation: Healthcare Science Research Institute, School of Healthcare Science Manchester Metropolitan University, John Dalton Building, Chester Street, M1 5GD Manchester, UK. Electronic address: n.al-shanti@mmu.ac.uk.
authors.forename: Nasser
authors.initials: N
authors.lastname: Al-Shanti
mesh_terms: D000375:Aging / Q000502:physiology*; D016922:Cellular Senescence / Q000276:immunology*; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D012038:Regeneration / Q000276:immunology*; D055948:Sarcopenia / Q000276:immunology*; D032496:Satellite Cells, Skeletal Muscle / Q000502:physiology*
keywords: Immune system; Muscle treg; Regeneration; Skeletal muscle