Inflammatory cells and mitotic activity of keratinocytes in gingival overgrowth induced by immunosuppressive- and nifedipine medication
Nurmenniemi, Petri (2006-02-07)
Both immunosuppressive and nifedipine medication have been associated with drug-induced gingival overgrowth. There are several hypothetical mechanisms for drug-induced gingival overgrowth, such as the influence of genetic predisposition, alterations in gingival tissue homeostasis, especially in the function of fibroblasts, and drug-induced action on growth factors. Clinical studies have also shown that, those with poor oral hygiene status drug-induced gingival overgrowth is more prevalent and severe than those with good oral hygiene status.
The working hypothesis was that immunosuppressive medication and/or nifedipine medication affects inflammatory cell profile and mitotic activity of keratinocytes in human overgrown gingiva. We studied gingival samples, collected from nifedipine-medicated cardiac outpatients and immunosuppression-medicated organ-transplant recipients. Patients were placed into four groups: 1) the immunosuppression group, patients receiving cyclosporin-A (CsA), azathioprine (AZA) and prednisolone (Pred) 2) the immunosuppression plus nifedipine group, patients receiving CsA, AZA, Pred. and nifedipine 3) the nifedipine group patients receiving only nifedipine and 4) the non-medicated control group. All of the samples related to moderate to severe degrees of gingival overgrowth, covering half to two thirds of the clinical crown. The aim of the study was to investigate the occurrence of Langerhans cells, macrophages, mast cells and mitotic activity of keratinocytes in human drug-induced overgrown gingiva, and consequently to assess their possible role in the pathogenesis of drug-induced gingival overgrowth.
We found that immunosuppressive medication increased the numbers of reparative macrophages (RM3/1) and decreased the numbers of tryptase- and chymase-positive mast cells (MCTC) cells. We have also shown that immunosuppressive and nifedipine medication decreased the numbers of Langerhans cells (CD1a) and increased the numbers of 27E10-macrophages parallelly. Additionally we found increase in the mitotic activity of gingival keratinocytes and even two-fold thickening of gingival epithelium in immunosuppressive and nifedipine medication-induced gingival overgrowth as compared with healthy gingiva. Immunosuppressive medication activated gingival epithelium (27E10 expression in gingival keratinocytes) more than nifedipine medication.
In conclusion, our results suggest that gingival overgrowth among immunosuppressive- and nifedipine-medicated patients is related to alteration of tissue homeostasis. First, this suggestion is supported by changes found in the numbers of cells that directly affect connective tissue turnover, e.g. reparative macrophages (RM3/1) and mast cells. Changes in the numbers of these cells could alter the cytokine- and growth factor-profile, which affects fibroblast function. Secondly, we found changes in the numbers of cells involved in regulation of inflammation, e.g. Langerhans cells and monocytes as compared with healthy controls. Immunosuppressive medication could directly activate gingival keratinocytes. We suggest that our findings mainly reflect the effects of immunosuppressive medication, but the role of inflammation cannot be excluded. The changes observed above represent differences of the pathogenesis of drug-induced gingival overgrowth between immunosuppressive and nifedipine medication. It must be however remembered that drug-induced gingival overgrowth is a result of multicausal intrinsic and extrinsic factors. Age, gender, concomitant medication with multiple drugs, plaque accumulation, and genetic disposition are additional risk factors. The abnormal distribution of specific immune system cell subpopulations does not alone prove a functional relationship to gingival overgrowth.
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