title: Toxoplasma gondii within skeletal muscle cells: a critical interplay for food-borne parasite transmission.
abstract: Toxoplasma gondii infects virtually any nucleated cell type of warm-blooded animals and humans including skeletal muscle cells (SkMCs). Infection of SkMCs by T. gondii, differentiation from the highly replicative tachyzoites to dormant bradyzoites and tissue cyst formation are crucial for parasite persistence in muscle tissue. These processes are also prerequisites for one of the major routes of transmission to humans via undercooked or cured meat products. Evidence obtained in vitro and in vivo indicates that SkMCs are indeed a preferred cell type for tissue cyst formation and long-term persistence of T. gondii. This raises intriguing questions about what makes SkMCs a suitable environment for parasite persistence and how the SkMC-T. gondii interaction is regulated. Recent data from our laboratory show that differentiation of SkMCs from myoblasts to syncytial myotubes, rather than the cell type itself, is critical for parasite growth, bradyzoite formation and tissue cyst maturation. Myotube formation is accompanied by a permanent withdrawal from the cell cycle, and the negative cell cycle regulator cell division autoantigen (CDA)-1 directly or indirectly promotes T. gondii stage conversion in SkMCs. Moreover, host cell cycle regulators are specifically modulated in mature myotubes, but not myoblasts, following infection. Myotubes also up-regulate the expression of various pro-inflammatory cytokines and chemokines after T. gondii infection and they respond to IFN-γ by exerting potent anti-parasitic activity. This highlights that mature myotubes are active participants rather than passive targets of the local immune response to T. gondii which may also govern the interaction between SkMCs and the parasite.
authors.affiliation: Institute for Medical Microbiology, University Medical Center Göttingen, Georg-August-University, Kreuzbergring 57, 37075 Göttingen, Germany.
authors.forename: Izabela J
authors.initials: IJ
authors.lastname: Swierzy
authors.affiliation: Institute for Medical Microbiology, University Medical Center Göttingen, Georg-August-University, Kreuzbergring 57, 37075 Göttingen, Germany.
authors.forename: Maisalreem
authors.initials: M
authors.lastname: Muhammad
authors.affiliation: Institute for Medical Microbiology, University Medical Center Göttingen, Georg-August-University, Kreuzbergring 57, 37075 Göttingen, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Kroll
authors.affiliation: Institute for Medical Microbiology, University Medical Center Göttingen, Georg-August-University, Kreuzbergring 57, 37075 Göttingen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Abelmann
authors.affiliation: Institute for Parasitology, University of Veterinary Medicine Hanover, Bünteweg 17, 30559 Hanover, Germany.
authors.forename: Astrid M
authors.initials: AM
authors.lastname: Tenter
authors.affiliation: Institute for Medical Microbiology, University Medical Center Göttingen, Georg-August-University, Kreuzbergring 57, 37075 Göttingen, Germany. Electronic address: clueder@gwdg.de.
authors.forename: Carsten G K
authors.initials: CG
authors.lastname: Lüder
mesh_terms: D000818:Animals; D005517:Foodborne Diseases / Q000469:parasitology*; D006801:Humans; D018485:Muscle Fibers, Skeletal / Q000469:parasitology*; D014122:Toxoplasma / Q000502:physiology*; D014123:Toxoplasmosis / Q000469:parasitology* / Q000635:transmission*
keywords: Cell cycle; Immune response; Myogenesis; Persistence; Skeletal muscle cell; Toxoplasma gondii