Mast cells of the human gingiva

By way of degranulation, the mast cells release a number of biologically active substances into the connective tissue. The present study is concerned with the relation of the gingival mast cells to the pathogenesis of gingivitis. Following fixation in Newcomer's fluid and non-aqueous staining at pH 0.5 in acridine orange¹, topographically defined zones of sections of normal and inflamed marginal gingiva, histologically classified with regard to degree of inflammation, of 56 different individuals have been studied in the fluorescence microscope. The human gingiva was found to be comparatively rich in mast cells. Three main morphological variants were observed and their topographical distribution within the tissue have been described. Marked differences in stainability between mast cells of different areas of the connective tissue have been recorded, and correlated to the state of inflammation, In spite of individual variations in mast cell density, definite patterns of frequency and distribution were observed. The number of mast cells appeared inversely correlated to the density and distribution of the inflammatory cellular exudate within the pocket area of the connective tissue. Consequently, normal gingivae generally contained more mast cells per tissue unit than the moderately inflamed tissue, which, in turn, contained more than the severely inflamed gingivae. Exceptions were found in some moderately inflamed, fibrous gingiva with evidence of strong fibroblastic activity, where there was an increased number of mast cells. On basis of the distribution, frequency and stainability of the mast cells of the gingiva, it is suggested that the mast cells of the regions adjacent to the tooth are subject to an enzymatic degranulation as elicited by products elaborated by the gingival bacterial plaque or possibly by local antigen-antibody interactions. Substances released by degranulation may then act as mediators during the course of the inflammatory process as well as contribute to the local resistance against injury.     

Presence of mast cells in various oral mucosal sites in juvenile and adult rats

The present investigation was designed to study the number of mast cells in various oral mucosal sites in juvenile and adult rats, with special reference to presence of subtypes of mast cells. Fifteen juvenile (1-month-old) and 15 adult (6-month-old) rats were used. Biopsies were taken from tongue, bucca, marginal gingiva (incisor area), and intestine (jejunum). For optimal preservation of the stainability of subtypes of mast cells, a fixative with low aldehyde concentration and low pH was used. The biopsies were embedded in paraffinwax. The first of three consecutive sections (5 μ) was stained in toluidine blue for 30 s, the second in toluidine blue for 7 days, and the third in astra blue/safranine. The total number of mast cells was represented by all cells positive to toluidine blue after 7 days' staining, or the sum of cells positive to astra blue and safranine. Cells positive to toluidine blue after 30 s were classified as connective tissue mast cells (CTMCs), and those positive after 7 days, but not after 30 s, as mucosal mast cells (MMCs). Cells positive to safranine in the astra blue/safranine staining sequence were classified as CTMCs, and those positive to astra blue as MMCs. Cells with intermediate staining characteristics in the astra blue/safranine staining sequence were recorded separately. The total number of mast cells in the tongue, buccal mucosa, and gingival mucosa was significantly higher in the juvenile than in the adult rats. In the buccal and gingival mucosa, more than twice as many mast cells were found in the young animals. In the intestine, however, the juvenile rats showed a significantly lower number of mast cells. In general, a higher number of cells with histochemical characteristics similar to the MMCs of the intestine was found in the oral sites of the juvenile animals. The differences in the total number of mast cells and the different composition of the mast cell population in the two age groups may indicate an age-related difference in the potential for biologic reactions involving mast cells.     

Mast cells of the human gingiva

Comparative histochemical studies with specific regard to the demonstration of mast cells were carried out on 21 different chronically inflamed marginal gingival specimens. For the demonstration of sulphated acid mucopolysaccharides two metachromatic stains were used-toluidine blue (pH 1.0) and acridine orange (pH0.5)-, as well as one orthochromatic stain- astra blue (pH 0.2–0.3). In addition the alcian blue-safranin sequence was employed to distinguish between weakly and strongly sulphated mucopolysaccharides. Trypsin-like esterase activity was demonstrated by the EACNAS-GBC technique. The metachromatic stains used stain mature mast cells specifically, while the non-metachromatic techniques stain immature mast cells as well. The chemical backgrounds for the different staining reactions are discussed. The chronically inflamed human gingivae were found to be rich in both mature and immature mast cells. The great majority of the immature mast cells were found within the pocket area of the connective tissue. Here, the number of mature mast cells was significantly smaller than in the oral area. The distribution of the different mast cell variants indicate a relation between mast cells and diffusible products from the gingival bacterial plaque.     

Mast cell heterogeneity in various oral mucosal sites in the rat.

Two distinct types of mast cells are recognized in the rat: connective tissue mast cells (CTMCs), found in the peritoneal cavity, skin, tongue, etc. and mucosal mast cells (MMCs), found in the intestinal mucosa. The two subsets differ functionally and can be defined by histochemical methods. The aim here was to characterize the mast cell population in various oral mucosal sites. Biopsies were taken from the tongue, buccal mucosa, gingival mucosa and intestine (jejunum) of 20 rats. For optimal preservation of the MMCs, a fixative with low aldehyde concentration and low pH was used. The biopsies were embedded in paraffin. The first of three consecutive sections (5 microns) was stained with toluidine blue for 30 s, the second with toluidine blue for 7 days and the third with astra blue/safranine. Cells positive with toluidine blue after 30 s were classified as CTMCs, and those positive after 7 days but not after 30 s as MMCs. Cells positive to safranine in the astra blue/safranine staining sequence were classified as CTMCs and those positive to astra blue as MMCs. The total number of mast cells was similar in the superficial layers of all oral tissues studied. There were more mast cells in the deeper than in the superficial portions of the tongue. Mast cells with staining characteristics and size similar to those observed in the intestinal mucosa (MMCs) were found together with 'classical' connective tissue mast cells (CTMCs). The results suggest that the mast cell population of oral mucosal tissues of the rat contains both CTMC- and MMC-like cells.     

Cell populations and episodic periodontal attachment loss in humans

The purpose of the present study was to assess possible associations between episodic probing attachment loss and cell populations in the supracrestal connective tissue in humans. 10 systemically healthy adult patients with untreated advanced periodontitis were monitored during a period of 10 months. At baseline and every month thereafter, probing attachment levels were measured at 6 sites of every tooth using an electronic pressure sensitive probe and flexible stents. Corresponding contralateral sites were identified where 1 site had lost 2 mm or more attachment within the previous month (P), and the other site had not (C). Supracrestal soft tissue biopsies were taken from these sites, processed and cut into 1 micron sections. Cell populations were identified in superficial and deep connective tissue areas by counting fibroblasts, macrophages, plasma cells, mast cells, granulocytes, lymphocytes, endothelial cells and the total number of inflammatory cells. Analysis of variance assessed differences in cell populations between P- and C-sites. There were statistically significantly higher numbers of fibroblasts in the standard areas of C-sites (p less than 0.0001). In P-sites, the numbers of macrophages, plasma cells, mast cells, lymphocytes and total inflammatory cells were significantly higher as compared to C-sites (p = 0.05-0.0001). There were no differences in cell populations between superficial and deep connective tissue areas within P- and C-sites (p greater than 0.2). Clinically assessed episodes of periodontal disease progression may be associated with site-specific shifts in inflammatory cell populations.     

A histological study of experimental gingivitis in man

Experimental gingivitis was induced in 21 individuals. Oral hygiene was abolished on the buccal and interproximal tooth surfaces of one side of the mouth in the mandibular premolar and molar area. The other tooth surfaces served as controls and were subject to thorough oral hygiene measures. After 15–17 days, when clinically manifest gingivitis had developed in the non-cleansing side of the majority of the subjects, biopsies were obtained from that side as well as from the control side. Histological examination of tissue from the experimental side revealed inflammatory infiltrates largely confined to the connective tissue adjacent to the pocket epithelium. The cells were mainly medium-large and small lymphocytes, macrophages and fibroblasts. A few neutrophilic leukocytes were observed mostly inside the vessels and adjacent to and within the pocket epithelium. Immature and mature plasma cells were seen in the central regions of the connective tissue, but were scant or absent nearer to the pocket epithelium The distribution of the different types of mononuclear cells might be consistent with a transformation of lymphocytes into plasma cells.     

Cell populations associated with active probing attachment loss.

The purpose of this study was to evaluate the ability of cell populations to differentiate between untreated progressing periodontitis sites (P) and untreated non-progressing sites (NP). Pairs of biopsies were obtained from untreated periodontal patients, one biopsy from a site which had lost probing attachment of 2 mm or more within the previous month, the other biopsy from a non-progressing site. Cell populations were identified on 1 micron sections in a defined connective tissue area at the junctional epithelium. The cell types counted were fibroblasts, mast cells, monocytes/macrophages, polymorphonuclear leukocytes (PMNs), lymphoid cells, plasma cells, endothelial cells, total inflammatory cells, and the total number of cells. The number of fibroblasts, mast cells, monocytes/macrophages, and inflammatory cells, as well as their percentage of the total number of cells, differed significantly between P- and NP-sites. In addition, the actual total counts differed between groups. The difference between groups was more significant for percent fibroblasts than for any other cell type. It appears that cell populations, particularly fibroblast counts, can aid in the histological discrimination between P and NP periodontitis lesions.     

Immunohistochemical expression of mast cell tryptase in giant cell fibroma and inflammatory fibrous hyperplasia of the oral mucosa

This study analysed the immunohistochemical expression of mast cell tryptase in giant cell fibromas (GCFs). In addition, the possible interaction of mast cells with stellate giant cells, as well as their role in fibrosis and tumour progression, was investigated. For this purpose, the results were compared with cases of inflammatory fibrous hyperplasia (IFH) and normal oral mucosa. Thirty cases of GCF, 30 cases of IFH and 10 normal mucosa specimens used as control were selected. Immunoreactivity of mast cells to the anti-tryptase antibody was analysed quantitatively in the lining epithelium and in connective tissue. In the epithelial component (p = 0.250) and connective tissue (p = 0.001), the largest mean number of mast cells was observed in IFHs and the smallest mean number in GCFs. In connective tissue, the mean percentage of degranulated mast cells was higher in GCFs than in IFHs and normal mucosa specimens (p < 0.001). Analysis of the percentage of degranulated mast cells in areas of fibrosis and at the periphery of blood vessels also showed a larger mean number in GCFs compared to IFHs and normal mucosa specimens (p < 0.001). The percent interaction between mast cells and stellate giant cells in GCFs was 59.62%. In conclusion, although mast cells were less numerous in GCFs, the cells exhibited a significant interaction with stellate giant cells present in these tumours. In addition, the results suggest the involvement of mast cells in the induction of fibrosis and modulation of endothelial cell function in GCFs.     

Immunolocalization of matrix metalloproteinases and TIMP-1 (tissue inhibitor of metalloproteinases) in human gingival tissues from periodontitis patients

The matrix metalloproteinases (MMPs) collagenase, gelatinase A (72 kDa gela-tinase), stromelysin, and their specific inhibitor TIMP-1 (tissue inhibitor of metalloproteinases), were immunolocalized using specific polyclonal antisera in gingival tissues from 21 patients with chronic inflammatory periodontal disease. Monoclonal antibodies against macrophages (Leu-M5), B cells (Leu-14), helper T cells (OKT4), suppressor T cells (OKT8) and the HLA-DR epitope were also used to identify leukocyte subsets. MMPs were observed in connective tissues at sites that histologically showed signs of remodelling. The number and distribution of positive cells varied widely, however, not only between individual biopsy specimens, but also within the same specimen. The same was true for the composition and distribution of the inflammatory cell infiltrate. Moreover, although there was a positive correlation between the number of MMP-producing cells and the severity of inflammation in some specimens, for others with comparable leukocyte subset scoring the number was reduced and sometimes absent altogether. Cells secreting MMPs were fibroblasts, macrophages and epithelial cells. It was not possible to determine unequivocally whether a MMP-positive cell within the connective tissue was a fibroblast or a macrophage, since the antisera recognise both fibroblast and macrophage MMPs and the different fixation requirements for MMPs (4% paraformaldehyde) and Leu-M5 (acetone) precluded co-localization on the same section. TIMP-1 was immunolocalized within connective tissue cells at sites of tissue remodelling. Our results support the hypothesis that tissue-derived MMPs may be involved in tissue remodelling in periodontal disease and conclusively demonstrate that epithelial cells may be involved as well as connective tissue cells.     

Identification of a tryptase-like enzyme in extracts of inflamed human gingiva by effector and gel-filtration studies

Inflamed gingiva contain a serine proteinase which could not previously be identified on the basis of its substrate specificity and inhibitor response. Using the substrate ZAlaArgArgAFC at alkaline pH, the enzyme was shown to be extracted more efficiently in high salt buffer. Inclusion of NaCl in assays, however, caused progressive reduction of activity. There was also inhibition by CaCl2, MgCl2 and 2 mM TosLysCH2Cl but not by 2 mM TosPheCH2Cl. Heparin produced significant activation. In gel filtrations with 1.0 M NaCl, activity appeared in fractions corresponding to a molecular weight of about 135,000. These properties are all consistent with tryptase from human mast cells. The enzyme may participate in both the connective tissue destruction and the inflammatory and immunological processes of gingivitis and periodontitis.     

Mast cells – a role in periodontal diseases?

OBJECTIVES: Limited attention has been given to the role mast cells may play in periodontal diseases. BACKGROUND: Mast cells are indeed found abundantly below and within several types of mucosal epithelia. On the basis of their proteinase content, mast cells are divided into connective tissue (CT) and mucosal phenotypes. The CT phenotype contains both tryptase and chymase (MC(TC)), while the mucosal phenotype contains only tryptase (MC(T)). The in vivo significance of different mast cell phenotypes has not yet been fully established. Mast cells are able to phagocytose, process and present antigens as effectively as macrophages. RESULTS: Recently mast cells were found in high numbers in chronically inflamed gingival tissue taken from patients with chronic marginal periodontitis (CMP). The number of mast cells was found to be even higher in HIV(+) patients with CMP. Furthermore, mast cells also express strongly matrix metalloproteinases (MMPs), which are key enzymes in degradation of gingival extracellular matrix. Mast cells may release preformed cytokines directing local innate and adaptive immune responses. The present review will focus on possible roles for mast cells in periodontal diseases. CONCLUSIONS: We certainly feel that this is a key cell in inflamed periodontal tissue and its role in periodontitis needs to be revisited.     

Histologic identification of mast cells in human dental pulp.

Previous investigators who attempted to identify mast cells in the dental pulp have used demineralizing or tooth-splitting procedures to obtain their tissue samples. However, Eda and Langeland15 found that the fluorescence of mast cells is destroyed by acid demineralizing agents. On the other hand, tooth splitting may damage the pulp by crushing it with forceps, or cutting and heating it with burs, stones, or discs. In the present study, we used the extirpated pulps from teeth in which endodontic access openings were made by means of high-speed rotary instruments with water spray. Metachromatic staining methods failed to demonstrate mast cells in any of the non-inflamed pulp specimens. Two of the inflamed pulp specimens revealed numerous mast cells which appeared intact and well preserved with no evidence of degranulation. As to the distribution of the mast cells, there was no correlation with the number and types of other inflammatory cells observed. Although several cells present in the specimens examined were suggestive of mast cells, only those cells that revealed definitive metachromasia were included in this study.     

Mast cell subpopulations in gingival overgrowth induced by immunosuppressive and nifedipine medication

BACKGROUND: An immunohistochemical study was conducted to compare distributions of mast cell subpopulations in normal human gingiva and in gingival overgrowth induced by nifedipine and immunosuppressive medication. METHODS: Gingival samples were collected from 12 triple-medicated organ transplant recipients (immunosuppression group), 11 triple-medicated organ transplant recipients taking nifedipine (immunosuppression plus nifedipine group), 11 nifedipine-medicated cardiac outpatients (nifedipine group), and 20 generally healthy individuals (control group). Cryostat sections were stained with mAbs for tryptase and chymase, and an avidin-biotin enzyme complex method was used to detect tryptase-positive mast cells (MC(T)), tryptase- and chymase-positive mast cells (MC(TC)), and chymase-positive mast cells (MC(C)). Total numbers of labeled cells were determined in connective tissue beneath the sulcular epithelium, connective tissue beneath the oral epithelium, and middle connective tissue. Statistical analyses were conducted using the Kruskal-Wallis test, the Mann-Whitney U-test, and Pearson's correlation test. RESULTS: In the three counting zones combined, numbers of MC(TC) cells and MC(C) cells were lower (P = 0.001 and P = 0.048, respectively) in the immunosuppression group than in the control group. The difference in numbers of MC(TC) cells was most marked in the middle connective tissue. Nifedipine medication had no effect on numbers of the mast cell subclasses. CONCLUSIONS: Immunosuppressive medication without concomitant nifedipine decreases the numbers of MC(TC) and MC(C) in overgrown gingiva. Chymase-positive mast cells may play a role in formation of gingival overgrowth, especially in patients receiving cyclosporin A (CsA) medication with no concomitant nifedipine. In this respect, nifedipine and CsA are different.     

牙周膜干细胞的研究进展

牙周病是一种由菌斑微生物引起的慢性感染性疾病,可引起牙周支持组织的破坏和丧失,最终导致牙齿松动脱落。牙周病治疗的最终目标是修复和重建受损的牙周支持组织。从牙周膜中分离获取的间充质干细胞具有成体干细胞的特性及多重分化潜能,可以分化为骨组织和牙周支持组织等多种类型的组织,这对牙周组织修复再生和牙周组织工程具有重大意义,因而备受关注。本文就牙周膜干细胞、牙周膜干细胞的生物学特性、牙周膜干细胞的影响因素及其调控机制等研究进展作一综述。     

Junctions between fibroblasts in mouse periodontal ligament

Quantitative evaluation of the distribution of intercellular junctions between fibroblasts in the incisor and molar periodontal ligament of the mouse indicated that structures resembling gap junctions are more frequent on the tooth side of this tissue than on the bone side. The difference was particularly evident for the ligament of the continuously erupting incisor. Here, the numerical density of gap junction-like structures was estimated to be approximately 20 per fibroblast in the connective tissue adjacent to the cementum and 4 per fibroblast in the tissue along the alveolar bone. With regard to the distribution of adhaerens-type junctions less variation was observed between the various zones of the incisor and molar ligament. For the incisor the average number of adhaerens-type junctions was calculated to be in the order of 30 junctions per cell in the tooth-related compartment and 20 junctions per cell in the alveolar compartment.
Although in the molar intercellular junctions were observed throughout the entire width of the ligament, in the incisor they were confined to the two main connective tissue compartments, i.e. the one of the tooth side which moves with the erupting tooth in the direction of the oral cavity, and the one of the bone side which remains stationary with respect to the alveolar wall. In the transitional area between the two latter compartments junctions were very sparse. It is suggested that the distribution pattern of intercellular junctions between fibroblasts in mouse periodontal ligament reflects functional differences among the cells in the various regions of the tissue, differences that are possibly related to processes involving the movement of cells and the metabolism of collagen.     

Mast cell expression in oral lichen planus: A systematic review

Lichen planus is a common chronic, inflammatory, immune‐mediated mucocutaneous disorder affecting the skin and mucosa. The role of mast cells in the genesis of lichen planus has been debated. Establishing a definitive part played by mast cells and its degranulation would possibly provide a permanent, cost‐effective treatment modality for oral lichen planus (OLP). This review aims to study the expression of mast cells qualitatively and quantitatively in OLP. The research questions were framed to assess the mast cell count, localization within the epithelium basement membrane zone and degranulation of mast cells. We performed a systematic search of PubMed, Medline, Cochrane and Web of Science. We found a total of 120 studies from which 12 were found suitable for the review. There is a marked increase in the number of mast cells in OLP. The mast cells were seen in increased numbers in the epithelial and connective tissue junction at areas of basement membrane disruption. There was also an increase in the degranulation of mast cells. It is evident that there is an increase in the mast cell number in lichen planus and its subsequent degranulation.     

Biologically active substances of the mast cell

The mast cells have been shown to contain a number of biologically active substances, some of which may contribute to the various phases of the inflammatory reaction. The present article deals with an evaluation of the potential role of the products of the mast cell metabolism in inflammation in general and in gingivitis in particular. In order for the various substances contained within the mast cells to act, they must be liberated into the connective tissue by degranulation of the cells. Among the released substances, histamine, proteolytic-esterolytic enzymes, "slow reacting substance", lysolecithins and heparin have been related to the development and course of inflammation in humans. Other factors, including, serotonin, unsaturated fatty acids and β-glucaronidase, seem to be of minor importance. The functions of the mast cell ascorbic acid, and phosphatases are not known.     

Mast cells in inflamed human dental pulp

abstract – Dental pulps from 45 caries-free primary or permanent teeth and from 24 carious primary teeth were investigated for presence of mast cells (MC). All the pulps were removed from split teeth and fixed in Newcomer's fluid or lead acetate-formalin. Serial sections stained with hematoxylin-eosin, astra blue (pH 0.2–0.3) + nuclear fast red, and toluidine blue (pH 1.0) demonstrated that pulps without inflammatory cells or with a few small lymphocytes were devoid of typical MC, even in the strongly metachromatic regions. However, MC were noted in all inflamed pulps; the number, distribution, and appearance of the MC depending upon the severity and type of the inflammatory reaction.