Integrin Signaling Imbalance in Periodontitis: A Stage-Dependent Link Between Inflammation, Bone Resorption and Regenerative Failure

Periodontitis is a chronic inflammatory disease driven largely by dysregulated host responses that lead to destruction of periodontal tissues. Integrins are heterodimeric transmembrane receptors that regulate cell adhesion and bidirectional signaling in epithelial cells, immune cells, periodontal ligament fibroblasts, and osteoclasts. During disease progression, integrin-related responses may shift across overlapping molecular phases. Epithelial integrins such as α3β1 and α6β4 support barrier integrity, whereas α5β1 may facilitate microbial interaction and inflammatory signaling. β2 integrins and α4β1 contribute to leukocyte recruitment and inflammatory amplification, whereas increased α9β1-associated signaling and reduced αvβ6-mediated regulation of transforming growth factor β (TGF-β) may promote inflammatory persistence. Matrix-associated integrins, including α2β1 and α11β1, support extracellular matrix (ECM) organization and mechanotransduction, whereas αvβ3 cooperates with Receptor activator of nuclear factor kappa B ligand (RANKL) to promote osteoclast activity and alveolar bone resorption. Impaired β1 integrin-dependent signaling and potentially reduced αvβ5-associated efferocytosis may contribute to defective resolution and regeneration. Importantly, integrin expression, activation, and downstream signaling are distinct, and the strength of evidence varies among integrin subtypes. This review proposes a conceptual framework in which periodontitis reflects a dynamic imbalance in integrin-mediated processes that link inflammation, bone resorption, and regenerative failure, rather than being a direct equivalent of clinical periodontal stages or grades.