Surface proteins mhp390 (P68) contributes to cilium adherence and mediates inflammation and apoptosis in Mycoplasma hyopneumoniae.

Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia (EP) and responsible for major economic losses in global swine industry. After colonization of the respiratory epithelium， M. hyopneumoniae elicits a general mucociliary clearance loss， prolonged inflammatory response， host immunosuppression and secondary infections. Until now， the pathogenesis of M. hyopneumoniae is not completely elucidated. This present study explores the pathogenicity of mhp390 (P68， a membrane-associated lipoprotein) by elucidating its multiple functions. Microtitrer plate adherence assay demonstrated that mhp390 is a new cilia adhesin that plays an important role in binding to swine tracheal cilia. Notably， mhp390 could induce significant apoptosis of lymphocytes and monocytes from peripheral blood mononuclear cells (PBMCs)， as well as primary alveolar macrophages (PAMs)， which might weaken the host immune response. In addition， mhp390 contributes to the production of proinflammatory cytokines， at least partially， via the release of IL-1β and TNF-α. To the best of our knowledge， this is the first report of the multiple functions of M. hyopneumoniae mhp390， which may supplement known virulence genes and further develop our understanding of the pathogenicity of M. hyopneumoniae.