pneumoniae infection in the bronchi and lung tissue leads to both insufficiency of lymphocytes at the periphery and negative conversion in the tuberculin test. Furthermore, it was reported that the onset of various autoimmune type extrapulmonary complications such as

Guillain-Barré syndrome, Stevens-Johnson syndrome, hepatitis, myocarditis and arthritis were ISRIB observed subsequent to M. pneumoniae infections [7–10]. Consequently, the participation of the excessive host immune response is thought to be involved in the severity of mycoplasmal pneumonia and also the onset of complications [11, 12]. In recent years, a third positive effector T cell subset known as Th17 cells were characterized by abundant production of IL-17 [13, 14]. IL-17 is more important than IFN-γ in onset and exacerbation Selleck BAY 1895344 of autoimmune diseases such as collagen-induced arthritis (CIA) and experimental allergic encephalitis (EAE), which are thought to be pathogenetically induced by the Th1 immune response [15, 16]. On the other hand, inducible regulatory T cells (iTreg) such as Tr1 and Th3 have been reported selleck products to contribute to the suppression of the hyperimmune response [17, 18]. It was reported that the Th17 cells are induced by segmented filamentous bacteria (SFB) which colonize the intestinal tract

[19]. However, the relationship of Th17 cells with the pathogenic mechanisms of mycoplasmal pneumonia and its extrapulmonary complications are not clear.

Treg Fludarabine in vivo has not previously been identified as an inhibiting factor of the M. pneumoniae inflammatory response. We have previously reported that experimental pneumonia can be caused by intranasal inoculation of M. pneumoniae soluble sonicated antigens to specific pathogen-free (SPF) mice [20, 21]. In the present study, we prepared a M. pneumoniae antigen induced inflammation model by use of SPF mice recurrently inoculated with M. pneumoniae antigens and performed pathological and immunological analyses to examine the induction mechanisms of Th17 and Treg cells. Additionally, we investigated the specificity of Th17 and Treg cell inducibility with mouse lymphocytes in vitro by using various bacterial antigens and immunoactivatory components. Methods Bacterial strains and culture conditions The reference strain M. pneumoniae M129, stocked at the Department of Infectious Diseases, Kyorin University School of Medicine was used in this study. M. pneumoniae cells were cultured at 37°C under a 5% CO2 atmosphere for 7 days in PPLO broth (Oxoid, Hampshire, UK) containing mycoplasma supplement-G (Oxoid) for the preparation of soluble M. pneumoniae antigens. Klebsiella pneumoniae (ATCC 13883; American Type Culture Collection, Rockville, MD) and Streptococcus pneumoniae (ATCC 33400) were cultured at 37°C under aerobic conditions for 18 hours in brain heart infusion broth (BHI; Becton Dickinson, MD) (BD Difco Franklin Lakes, NJ).