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Lupus-like oral mucosal lesions in mercury-induced autoimmune response in Brown Norway rats.

Seno K, Ohno J, Ota N, Hirofuji T, Taniguchi K - BMC Immunol. (2013)

Bottom Line: Dense infiltration of DC and macrophages was observed in the basement membrane (BM) zone of the oral epithelium.A linear and continuous smooth pattern of fluorescence was observed in the oral epithelial BM in addition to renal glomeruli, indicating immune complex deposits.Local autoimmune responses are involved in the pathogenesis of mercury-induced lupus-like lesions of the oral mucosa.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Morphological Biology, Division of Pathology, Fukuoka Dental College, 2-15-1 Tamura, Fukuoka, Japan. johno@college.fdcnet.ac.jp.

ABSTRACT

Background: Administration of mercury at nontoxic doses induces systemic autoimmune disease in Brown Norway (BN) rats. The pathogenesis of lupus-like oral mucosal lesion by mercury-induced autoimmunity is still unclear, even though the oral mucosa is observed to be commonly affected in mercury-treated BN rats. In this study, we investigated the immunopathology of lupus-like oral mucosal lesions in a model of mercury-induced systemic autoimmunity.

Methods: Brown Norway male rats were injected subcutaneously with either phosphate-buffered saline (control) or mercury at a dose of 1.0 mg per kilogram of body weight on days 0, 3, 5, and 7. Blood, kidney, and tongue samples were taken at various timepoints for evaluation by immunohistochemistry, RT-PCR, and lupus band test (LBT).

Results: Oral mucosal lesions were classified according to three consecutive temporal phases on the basis of infiltration of immunocompetent cells as follows: (phase I) infiltration of MHC class II+ dendritic cells (DC) and macrophages; (phase II) addition of ED1+ macrophage infiltrates; and (phase III) focal infiltration of pan T cells following increased infiltration of DC and macrophages. Dense infiltration of DC and macrophages was observed in the basement membrane (BM) zone of the oral epithelium. Tissue expression of IL-4 mRNA was detected in early lesions (phase I), suggesting that locally produced IL-4 may be responsible for Th2-mediated immune response. A linear and continuous smooth pattern of fluorescence was observed in the oral epithelial BM in addition to renal glomeruli, indicating immune complex deposits.

Conclusions: Local autoimmune responses are involved in the pathogenesis of mercury-induced lupus-like lesions of the oral mucosa.

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Antibody immunofluorescence (IF) analysis. A: Detection of antinuclear autoantibodies (ANA) by indirect IF using serum from the mercury-treated rats with phase III lesions, incubated on HEp-2 cells. Both nucleolar and nuclear cytoplasmic fluorescences are noted. Bar=50 μm. B: The reciprocal titer of IgG ANA in test serum samples from the rats in control and various phases. Horizontal bars denote median values. *, significantly different at p<0.05 compared with phase I. Controls show no titers. C: The reciprocal titer of autoantibodies bound to renal capillaries and basement membrane (BM) of the oral mucosa by indirect IF analysis. Horizontal bars denote median values. *, significantly different at p<0.05 compared with phases I. Controls show no titers. D: Indirect IF images of autoantibodies in the renal capillaries and basement membrane (BM) of the oral mucosa using serum from Brown Norway (BN) rats with phase III lesions. (A) IF reaction of the renal capillaries and mesangium is seen in the normal kidney. (B) IF labeling on the BM of the oral epithelium in normal tongue. Bars= 100 μm.
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Figure 5: Antibody immunofluorescence (IF) analysis. A: Detection of antinuclear autoantibodies (ANA) by indirect IF using serum from the mercury-treated rats with phase III lesions, incubated on HEp-2 cells. Both nucleolar and nuclear cytoplasmic fluorescences are noted. Bar=50 μm. B: The reciprocal titer of IgG ANA in test serum samples from the rats in control and various phases. Horizontal bars denote median values. *, significantly different at p<0.05 compared with phase I. Controls show no titers. C: The reciprocal titer of autoantibodies bound to renal capillaries and basement membrane (BM) of the oral mucosa by indirect IF analysis. Horizontal bars denote median values. *, significantly different at p<0.05 compared with phases I. Controls show no titers. D: Indirect IF images of autoantibodies in the renal capillaries and basement membrane (BM) of the oral mucosa using serum from Brown Norway (BN) rats with phase III lesions. (A) IF reaction of the renal capillaries and mesangium is seen in the normal kidney. (B) IF labeling on the BM of the oral epithelium in normal tongue. Bars= 100 μm.

Mentions: Autoimmune lesions resulting from exposure to mercury in mice are characterized by elevated levels of serum autoantibodies, including ANA and antibody to glomerular capillaries in kidney [13,18]. We performed ANA detection using HEp-2 cells. Serum samples, diluted 1:50, from the control rats barely bound to the HEp-2 cells. These cells remained negative when reacted with serum samples from the mercury-treated rats by day 4. Binding of serum samples, taken from the mercury-treated rats in phase I, was detected as combined nucleolar and nuclear cytoplasmic fluorescence in HEp-2 cells (Figure 5A). Figure 5B shows changes in serum titers during each phase of the study. The serum titer was undetectable in the control rats. After mercury-treatment, the titers increased with progression of the lesions. The serum titer in the mercury-treated rats was 400±67.87 in phase I , and it increased to 783.33±89.67 in phase II. In phase III, IgG ANA titer eventually reached 800±78.67. Reciprocal serum titer of IgG ANA in both phase II and III was significantly higher than that in phase I (p< 0.01) (Figure 5B).


Lupus-like oral mucosal lesions in mercury-induced autoimmune response in Brown Norway rats.

Seno K, Ohno J, Ota N, Hirofuji T, Taniguchi K - BMC Immunol. (2013)

Antibody immunofluorescence (IF) analysis. A: Detection of antinuclear autoantibodies (ANA) by indirect IF using serum from the mercury-treated rats with phase III lesions, incubated on HEp-2 cells. Both nucleolar and nuclear cytoplasmic fluorescences are noted. Bar=50 μm. B: The reciprocal titer of IgG ANA in test serum samples from the rats in control and various phases. Horizontal bars denote median values. *, significantly different at p<0.05 compared with phase I. Controls show no titers. C: The reciprocal titer of autoantibodies bound to renal capillaries and basement membrane (BM) of the oral mucosa by indirect IF analysis. Horizontal bars denote median values. *, significantly different at p<0.05 compared with phases I. Controls show no titers. D: Indirect IF images of autoantibodies in the renal capillaries and basement membrane (BM) of the oral mucosa using serum from Brown Norway (BN) rats with phase III lesions. (A) IF reaction of the renal capillaries and mesangium is seen in the normal kidney. (B) IF labeling on the BM of the oral epithelium in normal tongue. Bars= 100 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852543&req=5

Figure 5: Antibody immunofluorescence (IF) analysis. A: Detection of antinuclear autoantibodies (ANA) by indirect IF using serum from the mercury-treated rats with phase III lesions, incubated on HEp-2 cells. Both nucleolar and nuclear cytoplasmic fluorescences are noted. Bar=50 μm. B: The reciprocal titer of IgG ANA in test serum samples from the rats in control and various phases. Horizontal bars denote median values. *, significantly different at p<0.05 compared with phase I. Controls show no titers. C: The reciprocal titer of autoantibodies bound to renal capillaries and basement membrane (BM) of the oral mucosa by indirect IF analysis. Horizontal bars denote median values. *, significantly different at p<0.05 compared with phases I. Controls show no titers. D: Indirect IF images of autoantibodies in the renal capillaries and basement membrane (BM) of the oral mucosa using serum from Brown Norway (BN) rats with phase III lesions. (A) IF reaction of the renal capillaries and mesangium is seen in the normal kidney. (B) IF labeling on the BM of the oral epithelium in normal tongue. Bars= 100 μm.
Mentions: Autoimmune lesions resulting from exposure to mercury in mice are characterized by elevated levels of serum autoantibodies, including ANA and antibody to glomerular capillaries in kidney [13,18]. We performed ANA detection using HEp-2 cells. Serum samples, diluted 1:50, from the control rats barely bound to the HEp-2 cells. These cells remained negative when reacted with serum samples from the mercury-treated rats by day 4. Binding of serum samples, taken from the mercury-treated rats in phase I, was detected as combined nucleolar and nuclear cytoplasmic fluorescence in HEp-2 cells (Figure 5A). Figure 5B shows changes in serum titers during each phase of the study. The serum titer was undetectable in the control rats. After mercury-treatment, the titers increased with progression of the lesions. The serum titer in the mercury-treated rats was 400±67.87 in phase I , and it increased to 783.33±89.67 in phase II. In phase III, IgG ANA titer eventually reached 800±78.67. Reciprocal serum titer of IgG ANA in both phase II and III was significantly higher than that in phase I (p< 0.01) (Figure 5B).

Bottom Line: Dense infiltration of DC and macrophages was observed in the basement membrane (BM) zone of the oral epithelium.A linear and continuous smooth pattern of fluorescence was observed in the oral epithelial BM in addition to renal glomeruli, indicating immune complex deposits.Local autoimmune responses are involved in the pathogenesis of mercury-induced lupus-like lesions of the oral mucosa.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Morphological Biology, Division of Pathology, Fukuoka Dental College, 2-15-1 Tamura, Fukuoka, Japan. johno@college.fdcnet.ac.jp.

ABSTRACT

Background: Administration of mercury at nontoxic doses induces systemic autoimmune disease in Brown Norway (BN) rats. The pathogenesis of lupus-like oral mucosal lesion by mercury-induced autoimmunity is still unclear, even though the oral mucosa is observed to be commonly affected in mercury-treated BN rats. In this study, we investigated the immunopathology of lupus-like oral mucosal lesions in a model of mercury-induced systemic autoimmunity.

Methods: Brown Norway male rats were injected subcutaneously with either phosphate-buffered saline (control) or mercury at a dose of 1.0 mg per kilogram of body weight on days 0, 3, 5, and 7. Blood, kidney, and tongue samples were taken at various timepoints for evaluation by immunohistochemistry, RT-PCR, and lupus band test (LBT).

Results: Oral mucosal lesions were classified according to three consecutive temporal phases on the basis of infiltration of immunocompetent cells as follows: (phase I) infiltration of MHC class II+ dendritic cells (DC) and macrophages; (phase II) addition of ED1+ macrophage infiltrates; and (phase III) focal infiltration of pan T cells following increased infiltration of DC and macrophages. Dense infiltration of DC and macrophages was observed in the basement membrane (BM) zone of the oral epithelium. Tissue expression of IL-4 mRNA was detected in early lesions (phase I), suggesting that locally produced IL-4 may be responsible for Th2-mediated immune response. A linear and continuous smooth pattern of fluorescence was observed in the oral epithelial BM in addition to renal glomeruli, indicating immune complex deposits.

Conclusions: Local autoimmune responses are involved in the pathogenesis of mercury-induced lupus-like lesions of the oral mucosa.

Show MeSH
Related in: MedlinePlus