Periodontitis as an inflammatory trigger in hypertension: From basic immunology to clinical implications

Hypertension and periodontitis are both highly prevalent co-morbidities worldwide, and their occurrence increases with age. Multiple observational epidemiological studies have shown that periodontitis is associated with an increased cardiovascular disease (CVD) occurrence. Large systematic reviews and metanalyses further show that periodontitis increases the risk of hypertension and is associated with increased systolic and diastolic blood pressure. Genetic and clinical evidence, utilizing mendelian randomization and randomized clinical trials, support the causal role of periodontitis in hypertension. The mechanisms of this link remain unclear. Critical components of immune and inflammatory pathogenesis of periodontitis considerably overlap with immune mechanisms of hypertension. Clinical studies support that both C-reactive protein (CRP) levels and white blood cell counts (WBC) mediate the relationship between periodontal disease and high blood pressure. In particular, activation of Th1, Th17, T regulatory cells, and proinflammatory monocytes has been shown to be essential in both conditions. Immunosenescent dysregulated CD28null T cells have been implicated, along with key effector cytokines such as interleukin 6 (IL-6), TNF-alpha (TNF-α), interferon-gamma (IFN-γ), and interleukin 17 (IL-17). A better understanding of the relationships between hypertension and periodontitis is essential not only for possible utilization of this knowledge for a non-pharmacological approach to improving blood pressure control. It may also provide valuable pathogenetic clues linking inflammation and hypertension, which has become particularly relevant in the light of links between hypertension and autoimmune disorders or, more recently, COVID-19.