Inducible nitric oxide synthase expression in periodontitis

Recently, nitric oxide (NO) has been shown to be vital in inflammatory proc esses. Nitric oxide synthase (NOS) exists in three different isoforms, two constitutively produced with physiological roles, and an inducible form, iN OS, which is involved in inflammation. This study examined the localisation of iNOS in biopsies from patients with periodontitis using immunohistochem istry, and compared these with healthy tissue biopsies. Biopsies were obtai ned from 16 periodontitis patients undergoing periodontal surgery and from clinically healthy tissues of 5 patients having crown lengthening procedure s. The periodontitis diseased tissue demonstrated a greater level of iNOS e xpression than the healthy tissue. The source of iNOS in the periodontal ti ssues was determined by our monoclonal antibody to be the macrophage, with the endothelial cells also contributing. A role for NO in the inflammatory response of periodontal tissues is suggested, but the precise role requires further elucidation.