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Rheumatoid arthritis (RA) and periodontitis (PD) are chronic inflammatory disorders that cause bone loss. PD tends to be more prevalent and severe in RA patients. Previous experimental studies demonstrated that RA triggers alveolar bone loss similarly to PD. The aim of this study was to investigate if arthritis-induced alveolar bone loss is associated with modification in the oral microbiota. Checkerboard DNA-DNA hybridization was employed to analyze forty oral bacterial species in 3 groups of C57BL/6 mice: control (n = 12; without any challenge); Y4 (n = 8; received oral inoculation of Aggregatibacter Actinomycetemcomitans strain FDC Y4) and AIA group (n = 12; chronic antigen-induced arthritis). The results showed that AIA and Y4 group exhibited similar patterns of bone loss. The AIA group exhibited higher counts of most bacterial species analyzed with predominance of Gram-negative species similarly to infection-induced PD. Prevotella nigrescens and Treponema denticola were detected only in the Y4 group whereas Campylobacter showae, Streptococcus mitis and Streptococcus oralis were only found in the AIA group. Counts of Parvimonas micra, Selenomonas Noxia and Veillonella parvula were greater in the AIA group whereas Actinomyces viscosus and Neisseira mucosa were in large proportion in Y4 group. In conclusion, AIA is associated with changes in the composition of the oral microbiota, which might account for the alveolar bone loss observed in AIA mice., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Aim: This study aimed to investigate whether chronic antigen-induced arthritis (AIA) influences infection-induced periodontitis (PD) in mice and whether PD modifies the clinical course of AIA. The contribution of anti-TNF-α therapy was also evaluated., Materials and Methods: The PD was induced in C57BL/6 mice by oral infection with Aggregatibacter actinomycetemcomitans. AIA was induced after infection. Anti-TNF-α and chlorhexidine therapies were used to investigate the role of TNF-α and oral infection on PD and AIA interaction. Maxillae, knee joints, lymph nodes and serum samples were used for histomorphometric, immunoenzymatic and/or real time-PCR analyses., Results: Antigen-induced arthritis exacerbated alveolar bone loss triggered by PD infection. In contrast, PD did not influence AIA in the evaluated time-points. PD exacerbation was associated with enhanced production of IFN-γ in maxillae and expression of the Th1 transcription factor tBET in submandibular lymph nodes. Increased serum levels of IL-6 and C-reactive protein were also detected. Anti-TNF-α and antiseptic therapies prevented the development and exacerbation of infectious-PD. Anti-TNF-α therapy also resulted in reduced expression of IFN-γ, TNF-α and IL-17 in maxillae., Conclusions: Altogether, the current results indicate that the exacerbation of infection-induced PD by arthritis is associated with an alteration in lymphocyte polarization pattern and increased systemic immunoreactivity. This process was ameliorated by anti-TNF-α and antiseptic therapies., (© 2012 John Wiley & Sons A/S.)

Rheumatoid arthritis (RA) and periodontal disease (PD) are prevalent chronic inflammatory disorders that affect bone structures. Individuals with RA are more likely to experience PD, but how disease in joints could induce PD remains unknown. This study aimed to experimentally mimic clinical parameters of RA-induced PD and to provide mechanistic findings to explain this association. Chronic Ag-induced arthritis (AIA) was triggered by injection of methylated BSA in the knee joint of immunized mice. Anti-TNF-α was used to assess the role of this cytokine. Intra-articular challenge induced infiltration of cells, synovial hyperplasia, bone resorption, proteoglycan loss, and increased expression of cytokines exclusively in challenged joints. Simultaneously, AIA resulted in severe alveolar bone loss, migration of osteoclasts, and release of proinflammatory cytokines in maxillae. Anti-TNF-α therapy prevented the development of both AIA and PD. AIA did not modify bacterial counts in the oral cavity. PD, but not AIA, induced by injection of Ag in immunized mice was decreased by local treatment with antiseptic, which decreased the oral microbiota. AIA was associated with an increase in serum C-reactive protein levels and the expression of the transcription factors RORγ and Foxp3 in cervical lymph nodes. There were higher titers of anti-collagen I IgG, and splenocytes were more responsive to collagen I in AIA mice. In conclusion, AIA-induced PD was dependent on TNF-α and the oral microbiota. Moreover, PD was associated with changes in expression of lymphocyte transcription factors, presence of anti-collagen Abs, and increased reactivity to autoantigens.