Nitric oxide synthase type-II is synthesized by human gingival tissue and cultured human gingival fibroblasts

Nitric oxide is known to be an important inflammatory mediator, and is impl icated in the pathophysiology of a range of inflammatory disorders. The aim of this study was to determine the localization and distribution of endoth elial NOS (NOSII) in human gingival tissue, and to ascertain if human gingi val fibroblasts express NOS-II when stimulated with interferon gamma (IFN-g amma) and bacterial lipopolysaccharide (I-PS). The distribution of NOS-II i n inflamed and non-inflamed specimens of human gingivae was studied using a monoclonal antibody against nitric oxide synthase II. Cultures of fibrobla sts derived from healthy human gingivae were used for the cell culture expe riments. The results from immunohistochemical staining of the tissues indic ated an upregulation of NOS-II expression in inflamed compared to non-infla med gingival tissue. Fibroblasts and inflammatory cells within the inflamed connective tissue were positively stained for NOS-IT. Tn addition, basal k eratinocytes also stained strongly for NOS-II, in both healthy and inflamed tissue sections. When cultured human gingival fibroblasts were stimulated by INF-gamma and Porphyromonas gingivalis LPS, NOS-II was more strongly exp ressed than when the cells were exposed to LPS or IFN-gamma alone. These da ta suggest that, as for other inflammatory diseases, NO plays a role in the pathophysiology of periodontitis.