Changes to hepatocyte ploidy and binuclearity profiles during human chronic viral hepatitis.

BACKGROUND AND AIMS: The importance of the hepatocyte ploidisation pattern to the control of cell proliferation and differentiation has been well established. However, there are no data that have characterised hepatocyte ploidy at various stages of chronic liver inflammation and fibrosis in vivo. METHODS: We therefore investigated hepatocyte ploidy/binuclearity patterns in 57 patients with chronic hepatitis, using a recently developed methodology which allows simultaneous hepatocyte ploidy and binuclearity analyses on the same liver section. RESULTS: The percentage of mononuclear diploid hepatocytes was significantly reduced in patients with high hepatitis activity and marked fibrosis (low activity: 75.1 (18.8)% v high activity: 61.8 (21.6)%, p=0.0111, and low fibrosis: 77.3 (13.8)% v high fibrosis: 57.4 (23.3)%, p=0.0002). Accordingly, the percentage of mononuclear polyploid hepatocytes increased in patients with high hepatitis activity and marked fibrosis (low activity: 11.9 (15.5)% v high activity: 22.2 (20.1)%, p=0.0166, and low fibrosis: 9.4 (10.7)% v high fibrosis: 26.4 (21.6)%, p=0.0001). In addition, the fraction of binuclear hepatocytes was significantly higher in patients with hepatitis B virus (HBV) than in those with hepatitis C virus (HCV) infections (HBV: 18.2 (7.6)% v HCV: 12.0 (4.8)%; p=0.0020). Under multivariate analysis, HBV infection was an independent factor accounting for the larger binuclear hepatocyte fraction (p=0.0294). CONCLUSION: Our results revealed an increase in the polyploid hepatocyte fraction which correlates with the severity of chronic hepatitis; moreover, we demonstrated that HBV and HCV related chronic hepatitis exhibited distinctive hepatocyte ploidy patterns, thus allowing the suggestion that these two viral infections may modulate liver ploidy through different mechanisms.

Quantitative morphological analysis of Langerhans cells in healthy and diseased human gingiva.

Langerhans cells (LC) are implicated in the initiation and maintenance of inflammatory periodontal diseases. The purpose of this immunohistological study using morphometric and automated image analysis was to determine the morphological features of CD1a+ LC in healthy and inflammatory gingiva according to their localisation in the upper epithelium or the basal layer. The study was on gingival samples from 11 healthy controls (C), eight patients with gingivitis (G) and 12 patients with severe chronic adult periodontitis (P). The results show that in the basal layer of all experimental groups, the perimeter, surface and equivalent diameter of CD1a+ LC were significantly decreased (P<0.005) when compared with those in the upper epithelium of the same group. Furthermore, CD1a+ LC had become more rounded, reflected by a significant increase in form factor (P<0.005), when located close to the epithelial basal membrane. In the upper epithelium of group P, the perimeter, surface and equivalent diameter of CD1a+ LC were significantly decreased (P<0. 05) and the form factor significantly increased (P<0.05) when compared with the upper epithelium of group C. This work provides evidence for important morphological variations in CD1a+ LC according to their location within the epithelium and the severity of the periodontal disease. The observed morphological changes may reflect a cellular adaptation during the epithelial transmigration and could eventually be involved in immune stimulation during periodontitis.

Immunohistologic and morphometric analysis of cytotoxic T lymphocytes in gingivitis.

BACKGROUND: Gingivitis is an inflammatory phenomenon localized in gingival tissues and histologically characterized by an infiltration of several inflammatory cell populations. The purpose of this study was to characterize, localize, and quantify in situ inflammatory and cytotoxic T lymphocytes using immunolabeled gingival tissue sections in order to specify their implication during human gingivitis, since it is well known that such cells play an important role in the defense against bacterial elements. METHODS: Paraffin gingival tissue sections from 7 patients with gingivitis (G) and from 7 clinically and histologically healthy controls (C) were immunohistochemically stained by specific antibodies (anti-CD45, anti-CD3, anti-CD8, anti-CD20, anti-TIA-1, anti-GrB, and anti-CD68), allowing the quantification of inflammatory cells in upper gingival epithelium (Ep), in the basal epithelium layer (BEp), and in upper connective tissue (CT). Collagen fibers were stained by sirius red F3Ba in order to evaluate, by morphometric and automated image analysis, the surface occupied by collagen bundles and to histologically confirm the absence of pathology of the clinically selected healthy controls. RESULTS: In the gingivitis group, CD45+, CD3+, CD8+, TIA-1+, and GrB+ lymphocyte numbers were significantly increased in Ep (P<0.05); and CD45+, CD3+, and TIA-I+ lymphocyte numbers were significantly increased in BEp (P <0.05) compared respectively to Ep and BEp of group C. In Ep of group G, mean CD8+/CD3+ cell ratio was significantly increased (P<0.05) compared to BEp and CT, and 25% of TIA-1+ cytotoxic cells were activated GrB+ cells. CONCLUSIONS: The present study suggests that intraepithelial cytotoxic T lymphocytes play an important role during gingivitis and CD8 expression and that activation of TIA-1+ cytotoxic cells could be induced in Ep in response to epithelial environment. Thus, gingival epithelial tissue, which is generally only considered as a physical barrier, in fact contains numerous immune cell populations preventing the infiltration of pathogenic elements into the connective tissue. Particular clinical attention must be taken for the preservation of the epithelial tissue integrity.

Enteral nutrition modifies gut-associated lymphoid tissue in rat regardless of the molecular form of nitrogen supply.

BACKGROUND: It has been suggested that beneficial effect of elemental enteral diets in the treatment of inflammatory bowel diseases could be mediated by the suppression of protein dietary antigens. The objective of the present work was to study the effect of enteral diet on gut associated lymphoid tissue and on gastric Lactobacillus flora, in rat. METHODS: The effects of three molecular forms of nitrogen supply: amino acids, oligopeptides or whole casein, were compared in rats on continuous enteral diet. Frozen sections of small bowel were studied with monoclonal antibodies anti-CD5, -CD4, -CD8, -CD25, -macrophages, -MHC II. The Lactobacillus flora was also enumerated in the stomach, in order to assess the effect of ED on rat flora. RESULTS: Growth and mucosa morphology were identical in control and enteral groups. Rats on enteral diet showed, whatever was the molecular form of nitrogen supply, a decrease in CD5+, CD4+ and CD8+ intraepithelial cell numbers, but not in lamina propria cell number, and a decreased MHC II epithelial expression, when compared to control rats. The enterally fed rats also showed a decrease in Lactobacillus gastric contents. CONCLUSIONS: The current study demonstrates that continuous enteral nutrition modifies MHC II epithelial expression and gut associated lymphoid tissue cell number in rat, whatever is the molecular form of nitrogen supply. Intestinal flora could be responsible, at least for part, for these results.