Dextran-induced inflammation and its effect on keratinized gingival epithelium in monkeys

The cell population present during dextran-induced inflammation and its effect upon induced keratinization of the sulcular epithelium was investigated in two young adult male Rhesus monkeys. Keratinization of the sulcus epithelium was induced by a combined regimen of scaling, an intravenous injection of achromycin and daily rubber cup prophylaxes. After keratinization was confirmed by means of biopsies, inflammation was induced either by injecting 200 microliters of a 5% dextran saline solution or by applying the solution topically on the marginal gingiva for 2 weeks. Clinical grade dextran, molecular weight 70,000, was used. Physiologic saline solution, either injected or topical, was also used. At the same time, the daily prophylaxes were continued. After the 2 weeks, gingival biopsies were taken from each tooth treated with the different regimens. One-half of each biopsy was routinely processed and stained with hematoxylin and eosin or Rhodamine B, while the other half was processed for and stained with alcoholic and aqueous PAS to detect dextran in tissues. Histologic evaluation was carried out in three areas: a crestal zone, a cervical zone and an oral gingival zone. An Inflammatory Index (II) was determined and the width and length of keratin were measured. Dextran, either topical or injected, produced mainly a chronic inflammatory response characterized by lymphocytes (30-35%), monocytes-macrophages (5-10%), plasma cells (10%), polymorphonuclear leukocytes (PMNs) (15%) and unidentified cells (35%). Conversely, the physiologic saline-induced inflammation showed PMNs (75%), lymphocytes (5%) and unidentified cells (20%). The II for injected areas was significantly higher than for those topically treated or for nontreated controls. However, the increased II did not affect the degree of keratinization achieved.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of experimental leukopenia on chronic gingival inflammation in dogs

The effect of experimental leukopenia induced by nitrogen mustard on chronic gingival inflammation has been studied in dogs. The effect on the gingivae was assessed by measurements of crevicular leukocytes, gingival fluid and the level of acid phosphatasc activity in samples from gingival crevices. During leukopenia a reduction in all these parameters was observed. The values returned to normal in the post-leukopenic period. The results obtained indicate that crevicular leukocytes may contribute to the enzyme milieu in the gingival crevice and that these cells, through their lysosomal enzymes, may influence the tendency of the dento-gingival vessels to show increased permeability.     

Effect of anti-thymocyte serum on chronic gingival inflammation in dogs

The role of cellular immunity in chronic gingivitis has been studied in beagle dogs. The mechanism of delayed hypersensitivity in the animals was suppressed by administration of rabbit anti-dog-thymocyte globulin (ATS). The immunosuppressive effect of the antiserum was evaluated from the inhibition of a delayed hypersensitivity reaction in the skin to l-dinitro-2.4-chlorobenzene (DNCB). The level of gingival inflammation was determined before and after antiserum administration by measurements of crevicular leukocytes, gingival fluid and activity of acid phosphatase in crevicular samples.
Antiserum administration inhibited the hypersensitivity reactions in the skin towards DNCB. The gingival parameters were moderately reduced, but similar changes occurred in a group of control dogs injected with normal rabbit immunoglobulin. The results indicate that cellular immunity does not play a major role for the continuous maintenance of chronic gingivitis in the beagle dog.     

Effect of experimental leukopenia on chronic gingival inflammation in dogs

Leukopenia was induced in six beagle dogs with chronic gingivitis by the injection of heterologous anti-neutrophil scrum. During leukopenia, the number of neutrophils in the gingival crevice and within the gingival tissues was reduced. Concomitant with the reduction of neutrophils, the amount of gingival fluid decreased. The activity of acid phosphatase, hyaluronidase and protease in crevicular samples was determined and was found to decrease in parallel with the reduction in neutrophil number. All parameters returned to normal during the post-leukopenic period. The results of the present study support previous suggestions that neutrophils at the dento-gingival junction contribute to the enzyme milieu in the gingival crevice and that these cells, through their lysosomal enzymes, may induce vascular damage in periodontitis.     

Langerhans cells in the gingival epithelium

Langerhans cells (LCs) were specifically demonstrated by monoclonal antibody OKT 6. In healthy gingival tissue LCs were mainly seen in stratum spinosum of the surface epithelium. They had small nuclei and with long cell processes. The LCs of oral epithelium in marginal gingivitis and adult periodontitis tissue were more in numbers than in healthy tissue. In juvenile periodontitis tissue LCs numbers seemed to be increased obviously in comparison to the healthy tissue. The LCs were round and often located in both deep spinous and basal layers. These results demonstrate that LCs play an important role in the local immune response of the periodontal tissues.     

Sulcular exudate flow in gingival inflammation.

Sulcular exudate flow measurements were obtained from 45 subjects and compared to the clinical as well as histologic degrees of inflammation. The results of this investigation demonstrated no statistically significant difference between exudate flow and the clinical degree of inflammation while demonstrating a statistically significant difference between exudate flow and the clinical assessment of inflammation. It was proposed that current clinical indices do not accurately reflect the microscopic degree of gingival inflammation.     

Mucopolysaccharide localization in gingival epithelium

Short incubations, at 37°C, of small freshly excised pieces of healthy human gingivae iancorporated [³⁵S]-sulphate and [³H]-acetate into macromolecular material which could be precipitated intercellularly in the epithelium. Following radioactively pulse-chased incubations, such localization was observed by autoradiography on cryostat histological sections fixed in cetylpyridinium chloride. Critical electrolyte salt concentration elution indicated that most of the intercellular material was soluble in 0.63M-MgCl₂, and any material which remained was intracellular. In vitro and in vivo incorporation studies were compared. These data corroborate biochemical studies (Wiebkin, Bartold & Thonard 1979) together with other histochemical observations that proteoglycans (mucopolysaccharides) are a major intercellular component of human gingival epithelium. Molecular conformation and the relatively rapid synthesis and secretion rate for this class of epithelial macromolecule may explain the lack of susceptibility of this material in the intercellular site, both to degradation by some specific enzymes previously reported and to elution with critical salt concentrations from cationic detergent precipitates.
The method described, together with in vivo incorporation studies, provides a useful technique for studying direct effects of some microenvironmental influences on gingival epithelium.     

The ultrastructure of the gingival epithelium in smokers''melanosis

The ultrastructural morphology of melanocytes and keratinocytes was studied in clinically pigmented and non-pigmented gingival tissue from smokers and non-smokers. No differences were found between clinically pigmented lesions in smokers and non-smokers. In contrast, clinically non-pigmented tissue of smokers contained significantly more melanin-loaded keratinocytes as compared to that of non-pigmented non-smokers. In tissue of smokers and pigmented non-smokers melanocytes contained well melanized melanosomes (stages III and IV) as compared to non-pigmented tissue of non-smokers where stage II melanosomes dominated.
It was concluded that tobacco smoking may be a causative factor in melanin pigmentation of the oral mucosa and that smoking activates the epithelial melanin unit in a non-specific way. The hypothesis was put forward that in the oral mucosa melanin plays a role as a binder of toxic products such as free radicals and polycyclic compounds. In this way the epithelial melanin unit serves a protective function and prevents tissue damage.     

Fibrinolytic activity of gingival epithelium

Specimens of both human and animal gingivae were examined by fibrinolytic autography and all showed lysis over the gingival pocket epithelium, lysis never occurring over oral gingival epithelium. Epithelium separated from the connective tissue also showed fibrinolytic activity confined to the pocket epithelium. Examination of human gingival crevice washings showed fibrinolysis over some nucleated squamous epithelial cells as well as over anuclcated cell fragments. Although ihe neutrophil leucocytes in crevicular washings have fibrinolytic activity, this activity does not compare with that of the epithelium. The fibrinolytic activity of gingival pocket epithelium may be important in the pathogenesis of gingivitis and periodontitis, particularly due to the ability of plasmin lo activate complement.     

Mucopolysaccharide localization in gingival epithelium Factors affecting biosynthesis of sulphated proteoglycans in organ cultures of gingival epithelium

The effect of extraneous hyaluronidase, trypsin, hyaluronic acid, chrondroitin sulphate, and commercial heparin on the synthesis and secretion of proteoglycans (mucopolysaccharides) by gingival epithelium in short term incubations was investigated by autoradiography. Small pieces of human gingivae were incubated at 37°C in tissue culture medium (T.C. 199) for 75 min. The first 15 min incubation included a “pulse” of (³⁵S)-sulphate, after which the radioactive incorporation was “chased” in radioactive free medium. Cryostat sections of these pieces were cut, air dried, slide fixed with cetylpyridinium chloride, and prepared for autoradiography. The effect of the various additives in the “pulse” or the “chase” incubations on the autoradiographic localization of incorporated (³⁵S)-sulphate in the epithelium was noted. The responses by the epithelium to the enzymes hyaluronidase and trypsin were different. The former caused marked tissue disruption, probably due in part to degradation of the ground substance. Synthesis and secretion of sulphated macromolecules were evident when the lower concentrations of hyaluronidase were used. Tissue disruption appeared to be less severe. Trypsin in the medium of the gingival incubations appeared to cause both metabolic and secretory disruption. Both the sulphated polyanions, chrondroitin sulphate and heparin, when added to gingival incubations, showed inhibition of localization of (³⁵S)-sulphate label inlercellularly. Chrondroitin sulphate included in the “chase” incubations alone resulted in the inhibition, while only low concentrations of heparin caused any inhibition. These latter data were curious. The interpretations of a comparison of the data from “pulse” and “chase” additions of the non-sulphated hyaluronic acid imply that there was an initial inhibitory effect on secretion which in turn resulted in a subsequent regulation of synthesis of the intercellular sulphated macromolecules. These data and those derived from other tissues such as endothelium, cartilage, and chondrocyte cultures are briefly contrasted.     

Expression of fibronectin-binding integrins in gingival epithelium in drug-induced gingival overgrowth

BACKGROUND AND OBJECTIVE: Gingival overgrowth is a side-effect of nifedipine and cyclosporin medications. Integrins are transmembrane glycoproteins that mediate cell adhesion, regulate cell proliferation and participate in the regulation of tissue fibrosis. The aim of this study was to investigate whether expression of epithelial cell integrins is linked to the development of drug-induced gingival overgrowth. MATERIAL AND METHODS: Human gingival biopsies of patients taking nifedipine, cyclosporin, or a combination of both medications, were used. Expression of the alpha5beta1, alphavbeta1 and alphavbeta6 integrins, and of cellular extra domain A of fibronectin, was localized in frozen sections using immunohistochemistry. RESULTS: The activated conformation of the beta1, alpha5beta1 and alphavbeta6 integrins were more frequently expressed in distinct locations in the oral epithelium in the combined drug group. Cellular extra domain A of fibronectin, a ligand for both alpha5beta1 and alphavbeta6 integrins, was expressed within the connective tissue of all groups. It was also expressed around the basal keratinocytes of the control, nifedipine and cyclosporin-induced gingival overgrowth groups, but not in the combined medication group. No relationship between the presence of inflammation and integrin expression was found. CONCLUSION: The results indicate that expression of certain integrins is up-regulated in the epithelium of drug-induced gingival overgrowth where they could participate in controlling the formation of elongated rete ridges and tissue fibrosis.