Immunohistochemical analysis of inducible and endothelial forms of nitric oxide synthase in cyclosporin A-induced gingival overgrowth.
BACKGROUND
The contribution of nitric oxide (NO) to immune response and matrix degradation in the periodontal environment suggests a role for NO and NO-synthase (NOS) activity in the pathogenesis of cyclosporin A (CsA)-induced gingival overgrowth (GO). However, current knowledge on this topic is limited to experimental animal studies. The present study was undertaken on the basis of a hypothesis whether altered nitrite/nitrate levels in gingival crevicular fluid (GCF) and endothelial NOS (eNOS) and inducible NOS (iNOS) immunoreactivity in gingiva of CsA-treated patients contribute to the pathogenesis of CsA-induced GO.


METHODS
Twenty-four CsA-medicated renal transplant patients with GO (GO+; n = 12) or without GO (GO-; n = 12), 10 gingivitis, and 10 healthy subjects were included in the study. GCF samples from two proximal sites facing interdental papilla were collected, and papilla was excised. iNOS and eNOS were determined by immunohistochemistry. GCF nitrite/nitrate levels were analyzed based on the Griess reaction.


RESULTS
Weak iNOS immunostaining was observed in the healthy and GO- groups. In the gingivitis and GO+ groups, iNOS immunostaining significantly increased in connective tissue. Epithelial immunostaining of iNOS was localized to basal keratinocytes and the lower layer of stratum (str.) spinosum in the gingivitis group. In the GO+ group, iNOS immunostaining was differentially localized to keratinocytes of str. superficiale but considerably decreased in the str. basale. Weak eNOS immunostaining was found in the healthy and GO- groups, whereas higher immunostaining was observed in the gingivitis and GO+ groups. No intergroup differences were observed regarding nitrite/nitrate levels in GCF.


CONCLUSIONS
CsA differentially upregulated iNOS, but not eNOS, in overgrown gingiva, which may play a pivotal role in the pathogenesis of CsA-induced GO.
Department of Periodontology, School of Dentistry, Ege University, Izmir, Turkey. ali.gurkan@ege.edu.tr
Ali
A
Gürkan
Gülnur
G
Emingil
Gülperi
G
Oktem
Nur
N
Selvi
Beral
B
Afacan
Tunç Ilgenli
Hüseyin
H
Töz
Gül
G
Atilla
D000293:Adolescent; D000328:Adult; D003238:Connective Tissue / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D016572:Cyclosporine / Q000009:adverse effects*; D003774:Dental Plaque Index; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D004848:Epithelium / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D005260:Female; D005881:Gingiva / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D005883:Gingival Crevicular Fluid / Q000737:chemistry / Q000201:enzymology; D019214:Gingival Overgrowth / Q000139:chemically induced* / Q000201:enzymology / Q000473:pathology; D005891:Gingivitis / Q000201:enzymology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007150:Immunohistochemistry; D007166:Immunosuppressive Agents / Q000009:adverse effects*; D015603:Keratinocytes / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000032:analysis; D052247:Nitric Oxide Synthase Type II / Q000032:analysis*; D052250:Nitric Oxide Synthase Type III / Q000032:analysis*; D009573:Nitrites / Q000032:analysis; D010512:Periodontal Index; D055815:Young Adult
D007166:Immunosuppressive Agents; D009566:Nitrates; D009573:Nitrites; D016572:Cyclosporine; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III