Gut microbiota and the periodontal disease: role of hyperhomocysteinemia.

Periodontal disease is one of the most common conditions resulting from poor oral hygiene and is characterized by a destructive process in the periodontium that essentially includes gingiva, alveolar mucosa, cementum, periodontal ligament, and alveolar bone. Notably, the destructive event in the alveolar bone has been linked to homocysteine (Hcy) metabolism; however, it has not been fully investigated. Therefore; the implication of Hcy towards initiation, progression, and maintenance of the periodontal disease remains incompletely understood. Higher levels of Hcy (also known as hyperhomocysteinemia (HHcy)) exerts deleterious effects on gum health and teeth in distinct ways. Firstly, increased production of proinflammatory cytokines such as TNF-α, IL-1β, IL-6, and IL-8 leads to an inflammatory cascade of events that affect methionine (Met) and Hcy metabolism (i.e., 1-carbon metabolism) leading to HHcy. Secondly, metabolic dysregulation during chronic medical conditions increases systemic inflammation leading to a decrease in vitamins, more specifically B6, B12, and folic acid, that play important roles as cofactors in Hcy metabolism. Also, given the folate level in the HHcy state that is important during dysbiosis, these two conditions appear to be intimately related, and in this context, HHcy-induced dysbiosis may be one of the potential causes of periodontal disease. This paper sums up the link between periodontitis and HHcy, with a special emphasis on the "oral-gut microbiome axis" and the potential probiotic intervention towards warding off some of the serious periodontal disease conditions.