Microbiota is a balanced ecosystem that has important functions to the host health including development, defense, digestion, and absorption of dietary fibers and minerals, vitamin synthesizes, protection, and training the host immune system. On the other hand, its dysbiosis is linked to many human diseases such as rheumatoid arthritis (RA). The RA is an inflammatory autoimmune disorder caused by genetic and environmental factors; microbiota may be considered as a risk environmental factor for it. Citrullination is a post-translation modification (PMT) that converts the amino acid arginine to amino acid citrulline in certain proteins. These citrullinated proteins are recognized as a foreign antigen by the immune system resulting in the upregulation of inflammatory action such as in RA. The current work highlights the effect of both gut and oral microbiota dysbiosis on the development of RA, as well as discusses how the alteration in microbiota composition leads to the overgrowth of some bacterial species that entangled in RA pathogenicity. The evidence suggested that some oral and gut microbial species such as Porphyromonas gingivalis and Prevotella copri, respectively, contribute to RA pathogenesis. During dysbiosis, these bacteria can mediate the citrullination of either human or bacteria proteins to trigger an immune response that leads to the generation of autoantibodies.

微生物群是一个平衡的生态系统，对宿主健康具有重要的功能，包括膳食纤维和矿物质的发育、防御、消化和吸收，维生素合成、保护和训练宿主免疫系统。另一方面，它的生态失调与许多人类疾病有关，例如类风湿性关节炎 (RA)。RA是一种由遗传和环境因素引起的炎症性自身免疫性疾病；微生物群可能被认为是它的风险环境因素。瓜氨酸化是一种翻译后修饰 (PMT)，可将某些蛋白质中的氨基酸精氨酸转化为氨基酸瓜氨酸。这些瓜氨酸化蛋白被免疫系统识别为外来抗原，导致炎症作用上调，例如在 RA 中。目前的工作强调了肠道和口腔微生物群失调对 RA 发展的影响，并讨论了微生物群组成的改变如何导致一些与 RA 致病性纠缠的细菌物种过度生长。证据表明，一些口腔和肠道微生物物种，如Porphyromonas gingivalis 和 Prevotella copri分别有助于 RA 发病机制。在生态失调期间，这些细菌可以介导人类或细菌蛋白质的瓜氨酸化，以触发导致自身抗体产生的免疫反应。