RESUMO
Autoimmune diseases (AIDs) remain an enigma to the current understanding of immune system functioning. Identifying their etiologies remains a major challenge, despite growing knowledge. The oral cavity has a very special place in regard to AIDs. The oral mucosa, the most exposed body's natural barrier to pathogens, plays a role in both education of the immune system and the organism's daily protection. On the one hand, systemic disturbance of the immune system can impact the oral sphere with early signs which are useful diagnostic tools. On the other hand, the current research efforts on interactions between microbiota and the immune system allow an update of the old hypothesis involving an initial infection to trigger autoimmunity. Dysbiosis of our microbiota, especially in the oral sphere, could lead to a breakdown in tolerance mechanisms. Immune tolerance has to maintain the integrity of the organism but also cohabitation with commensal microbiota. The relationship between periodontitis, a chronic infectious disease, and rheumatoid arthritis, one of the most common systemic autoimmune disorders, illustrates the possible relationship between chronic infections and the etiopathogenesis of autoimmunity. Indeed, its association with oral pathogens involved in periodontal damage raises questions about a possible infectious etiology of rheumatoid arthritis (RA) which would place the management of periodontitis not only as mandatory RA's support therapy but also as a prophylactic gesture to prevent autoimmunity.
Title: Auto-immunité et cavité orale, où en est-on en 2023 ? Abstract: Les maladies auto-immunes (MAI) restent une énigme dans notre compréhension du système immunitaire. L'identification de leurs étiologies demeure un défi majeur en dépit d'une augmentation exponentielle de nos connaissances sur le fonctionnement du système immunitaire. La cavité orale a une place particulière vis-à-vis des MAI. La muqueuse buccale présente les barrières naturelles de l'organisme parmi les plus exposées à des agents pathogènes. À ce titre, elles jouent un rôle dans l'éducation du système immunitaire, puis dans la protection quotidienne de l'organisme. Les perturbations du système immunitaire se manifestent fréquemment par des conséquences au niveau de la sphère buccale, le plus souvent précocement, permettant d'initier une démarche diagnostique. L'effort de recherche actuel sur les interactions entre microbiotes et système immunitaire permet de moderniser l'hypothèse historique liant une origine infectieuse à l'apparition de l'auto-immunité, en y apportant quelques nuances.
Assuntos
Artrite Reumatoide , Doenças Autoimunes , Periodontite , Humanos , Autoimunidade , Artrite Reumatoide/etiologia , Periodontite/complicações , Disbiose/complicaçõesRESUMO
Periodontal diseases are common inflammatory conditions characterized by bone loss in response to simultaneous bacterial aggression and host defenses. The etiology of such diseases is still not completely understood, however. It has been shown that specific pathogens involved in the build-up of dysbiotic biofilms participate actively in the establishment of periodontitis. This multifactorial pathology also depends on environmental factors and host characteristics, especially defenses. The immune response to the pathogens seems to be critical in preventing the disease from starting but also contributes to tissue damage. It is known that small molecules known as antimicrobial peptides (AMPs) are key actors in the innate immune response. They not only target microbes, but also act as immuno-modulators. They can help to recruit or activate cells such as neutrophils, monocytes, dendritic cells, or lymphocytes. AMPs have already been described in the periodontium, and their expression seems to be connected to disease activity. Alpha and beta defensins and LL37 are the AMPs most frequently linked to periodontitis. Additionally, leukocyte infiltrates, especially B-cells, have also been linked to the severity of periodontitis. Indeed, the particular subpopulations of B-cells in these infiltrates have been linked to inflammation and bone resorption. A link between B-cells and AMP could be relevant to understanding B-cells' action. Some AMP receptors, such as chemokines receptors, toll-like receptors, or purinergic receptors, have been shown to be expressed by B-cells. Consequently, the action of AMPs on B-cell subpopulations could participate to B-cell recruitment, their differentiation, and their implication in both periodontal defense and destruction.