Nifedipine and phenytoin induce matrix synthesis, but not proliferation, in intact human gingival connective tissue ex vivo

Abstract

Drug-induced gingival enlargement (DIGE) is a fibrotic condition that can be caused by the antihypertensive drug nifedipine and the anti-seizure drug phenytoin, but the molecular etiology of this type of fibrosis is not well understood and the role of confounding factors such as inflammation remains to be fully investigated. The aim of this study was to develop an ex vivo gingival explant system to allow investigation of the effects of nifedipine and phenytoin alone on human gingival tissue. Comparisons were made to the histology of human DIGE tissue retrieved from individuals with DIGE. Increased collagen, fibronectin, and proliferating fibroblasts were evident, but myofibroblasts were not detected in DIGE samples caused by nifedipine and phenytoin. In healthy gingiva cultured in nifedipine or phenytoin-containing media, the number of cells positive for p-SMAD2/3 increased, concomitant with increased CCN2 and periostin immunoreactivity compared to untreated explants. Collagen content assessed through hydroxyproline assays was significantly higher in tissues cultured with either drug compared to control tissues, which was confirmed histologically. Matrix fibronectin levels were also qualitatively greater in tissues treated with either drug. No significant differences in proliferating cells were observed between any of the conditions. Our study demonstrates that nifedipine and phenytoin activate canonical transforming growth factor-beta signaling, CCN2 and periostin expression, as well as increase collagen density, but do not influence cell proliferation or induce myofibroblast differentiation. We conclude that in the absence of confounding variables, nifedipine and phenytoin alter matrix homeostasis in gingival tissue explants ex vivo, and drug administration is a significant factor influencing ECM accumulation in gingival enlargement.

JNK Signaling as a Key Modulator of Soft Connective Tissue Physiology, Pathology, and Healing

“…Providing evidence that FAK and JNK are downstream mediators of periostin induction of fibronectin and type I collagen expression in human gingival fibroblasts, it opens the intriguing possibility that periostin based biomaterials could be used, clinically, as a means of stimulating matrix synthesis during gingival healing [15]. It also provides insights into the pathology of DIGE, an inflammatory condition which we have shown is associated with overexpression of periostin [117][118][119]. Induction of matrix synthesis in the presence of periostin would also partially explain the overgrowth of gingival tissue associated with the condition.…”

“…Myofibroblast differentiation has been postulated to be an important cellular transition in gingival wound healing, although we recently reported that α-SMA positive myofibroblasts are absent during gingival healing in a rat model [15] and we have previously shown that myofibroblasts are not associated with drug-induced gingival enlargement (DIGE), a fibrotic condition of the gingiva [117][118][119]. TGFβ1 has been shown to induce myofibroblast differentiation through canonical and noncanonical signaling [120][121][122].…”

Titanium Substratum Roughness as a Determinant of Human Gingival Fibroblast Fibronectin and α-Smooth Muscle Actin Expression

“…Three specific TGF-β isoforms have been identified, with specific differences in their role in wound healing particularly in skin [ 37 ]. Indeed, much work on TGF-β isoforms in gingival tissue relates to drug-induced gingival enlargement, which is associated with increased ECM production [ 38 ], but α-SMA upregulation [ 39 , 40 ]. TGF-β1 is considered to be pro-fibrotic and some evidence suggests that TGF-β3 is anti-fibrotic, although the latter remains somewhat controversial with conflicting results in the literature [ 41 , 42 , 43 ].…”

Histological and Immunohistochemical Study of the Effect of Topically Applied Phenytoin on Chemically Induced Buccal Mucosal Ulcer in Albino Rats

“…This finding is in parallel with Kantarci et al, [41] who reported reduction of apoptosis in fibroblasts rather than proliferation due to decreased inflammation attained by phenytoin action. Furthermore, Kim et al, [42] reported that phenytoin did not significantly increase proliferation of c.t cells, and suggested that PIGE was only due to increased matrix deposition.…”