No abstract

Cyclosportne a (csa) is a widely used immunosuppressant for transplant patients and is also used for the treatment of a wide variety of systemic diseases with immunologic components. A prominent side effect of CSA administration is gingival overgrowth (hyperplasia). It has been postulated that CSA alters fibroblast activity through effects on various growth factors/cytokines. However, as yet, data concerning the molecular mechanisms involved in pathologic connective tissue proliferation are preliminary in nature. Our previous investigations concerning phenytoin‐induced effects on platelet‐derived growth factor B (PDGF‐B) gene expression have demonstrated that other drugs which cause gingival overgrowth can upregulate macrophage PDGF‐B gene expression in vitro and in vivo. The purpose of the present study was to evaluate PDGF‐B gene expression in gingival tissues of patients receiving CSA therapy and exhibiting gingival overgrowth to determine if similar PDGF‐B upregulation occurs in response to CSA and to identify PDGF‐B producing cells in these tissues. Quantitative competitive reverse transcription polymerase chain reaction (QC‐RTPCR) techniques were utilized to measure PDGF‐B mRNA levels in CSA overgrowth patients and normal controls (N = 6/group). Results were expressed as mean ± mRNA copy number and tested for significance using unpaired t‐tests. Gingival samples were harvested (standardized for local inflammation at the sample site), total RNA was extracted, and QC‐RTPCR was performed using specific PDGF‐B primers and a corresponding competitive internal standard. CSA‐treated patients exhibiting gingival overgrowth demonstrated approximately 48‐fold increase in PDGF‐B mRNA (7667.1 ± 477.4 copies for CSA patients vs. 158.2 ± 37.1 copies for controls; P < 0.001). Additionally, dual fluorescence immunohistochemistry for mature macrophage marker antigen (CD51) and intracellular PDGF‐B was utilized to identify and localize PDGFB producing cells in hyperplastic gingiva of CSA‐treated patients. PDGF‐B producing cells were demonstrated to be macrophages distributed in a non‐uniform manner throughout the papillary connective tissue. These results further support the hypothesis that the molecular mechanisms responsible for drug‐induced gingival overgrowth may involve upregulation of PDGF‐B macrophage gene expression. We continue to investigate specific CSA‐induced alterations of macrophage PDGF‐B gene expression in vitro and in vivo. J Periodontol 1996;67:271–278.

Diabetes (type I and type II) affects approximately 13 million people in the United States. Delayed and incomplete healing of wounds can be a major problem for diabetic patients. Macrophages are an important cell in the complex process of wound repair representing the major source of cytokines throughout the wound-healing process. Cytokines mediate many of the cellular responses critical to timely wound repair. It has been suggested that diabetes impairs wound healing through disruption of local cytokine production. Our previous in vivo studies in rats demonstrated that diabetes-induced and diet-induced hyperlipidemia cause changes in macrophage phenotype and function (Iacopino 1995; Doxey et al. 1998), suggesting that alterations in macrophage cytokine profiles represent the cellular/molecular mechanism responsible for delayed wound healing. The purpose of this study was to investigate how monocyte maturation/differentiation and cytokine production were altered by serum lipids in an in vitro system using human cells. Commercially prepared purified human monocytes were cultured and exposed to serum lipids. Phenotypic analysis of differentiated macrophages was then performed by flow cytometry and fluorescent microscopy using surface antigens specific for various macrophage subsets. Selected cytokines in conditioned medium were assayed using commercial human enzyme-linked immunosorbent assay (ELISA) kits. We demonstrate that serum lipids cause an increase in monocytic differentiation leading to an inflammatory macrophage phenotype rather than a reparative/proliferative phenotype. We also show that serum lipids cause a generalized decrease in macrophage cytokine production using interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), platelet-derived growth factor (PDGF), and transforming growth factor beta 1 (TGF-beta 1) as marker cytokines. Our present in vitro results using human cells confirm our previous in vivo studies in the rat and support the hypothesis that diabetes-induced hyperlipidemia alters the monocyte differentiation process resulting in changes of macrophage subsets and cytokine release at the wound site, ultimately impairing the wound-healing process.