Mechanisms of neonatal tolerance induced in an animal model for primary Sjögren's syndrome by intravenous administration of autoantigen.

Neonatal exposure to autoantigen is believed to induce effective antigen-specific T-cell tolerance in experimental models of autoimmunity. We have identified 120 kDa alpha-fodrin autoantigen in an animal model for primary Sjögren's syndrome (SS), that has been determined as a candidate autoantigen in both an animal model and the patients with primary SS. We demonstrate here that neonatal injection of autoantigen induce relevant tolerance when treated with intravenous (i.v.) administration within 24 h after birth, but not with i.v. injection after the thymectomy or with intraperitoneal injection. Autoantigen-specific T-cell response was significantly reduced in mice induced neonatal tolerance, and the activation markers of splenic CD4+ T cells were down-regulated in mice treated with neonatal administration. Because we detected that neonatal i.v. injection of autoantigen prevented Th1 response, it is possible that the autoantigen administration within 24 h after birth induce regulatory T cells that had a protective effect against Th1-mediated autoimmune diseases. These results indicate that the prevention of the spontaneous anti-120 kDa alpha-fodrin response in vivo, by tolerization of the autoantigen-reactive T cells, blocked the development of autoimmune lesions in an animal model for primary SS.

Autoantigen-specific CD4+CD28low T cell subset prevents autoimmune exocrinopathy in murine Sjögren's syndrome.

Organ-specific autoimmune exocrinopathy resembling Sjögren's syndrome (SS) that spontaneously develops in NFS/sld mutant mice thymectomized 3 day after birth is dependent on Th1-type CD4+ T cells. We previously reported that a cleavage product of 120-kDa alpha-fodrin may be an important autoantigen in the pathogenesis of SS in both an animal model and the patients. We demonstrate that in an animal model of SS with overt exocrinopathy, a unique CD4+ T cell subset expressing CD28low is dramatically increased in spleen cells before the disease onset, but that the CD4+ T cells of diseased mice were virtually all CD28high. We found that the spleen cells in these mice before the disease onset showed a significant increase in autoantigen-specific T cell proliferation. Analysis of in vitro cytokine production by spleen cells indicated, before the disease onset, severely impaired production of IL-2 and IFN-gamma in the animal model, whereas high levels of IL-4 were observed. Expression of cytokine genes, including IL-4, IL-10, and TGF-beta, was detected in FACS-sorted CD4+CD28low T cells by RT-PCR analysis. Transfer of CD4+CD28low T cells into the animal model actually prevented the development of autoimmune lesions including autoantibody production. These results suggest that a CD4+CD28low T cell subset that is continuously activated by an organ-specific autoantigen may play a regulatory role in the development of organ-specific autoimmune disease in an animal model of SS.

Severe destructive autoimmune lesions with aging in murine Sjögren's syndrome through Fas-mediated apoptosis.

When we evaluated the age-associated changes in autoimmune exocrinopathy in a NFS/sld murine model for primary Sjögren's syndrome (SS), severe destructive autoimmune lesions developed in the salivary and lacrimal glands in the aged mice, compared with those observed in the younger model. We detected a decreased secretion of saliva and tear flow in the aged group. A significant increase of TUNEL(+)-apoptotic epithelial duct cells in the salivary glands was detected in the aged SS animal model. A higher proportion of mouse salivary gland cells bearing Fas was found in the aged group, whereas no significant changes were seen on tissue-infiltrating CD4(+) T cells bearing FasL in the salivary glands from young and aged mice. We detected an increased cleavage product of organ-specific autoantigen, 120-kd alpha-fodrin, in the aged salivary gland tissues on immunoblotting, and an increase in serum autoantibody production against 120-kd alpha-fodrin by enzyme-linked immunosorbent assay. An increase in the proliferative response of splenic T cells against organ-specific autoantigen was observed, whereas nonspecific concanavalin A responsiveness was decreased in the aged mice. In addition, a decrease in Fas expression was found on splenic CD4(+) T cells in the aged mice, and anti-Fas mAb-stimulated apoptosis was down-regulated on CD4(+) T cells. These results indicate that age-associated dysregulation of CD4(+) T cells may play a crucial role on acceleration of organ-specific autoimmune lesions in a murine model for primary SS through Fas-mediated apoptosis.

Treatment with anti-CD86 costimulatory molecule prevents the autoimmune lesions in murine Sjögren's syndrome (SS) through up-regulated Th2 response.

Intraperitoneal administration with anti-CD86 (B7.2) MoAb into the murine model for primary SS in NFS/sld mutant mice resulted in dramatically inhibitory effects on the development of autoimmune lesions, while no significant effects were observed when the mice were administered with anti-CD80 (B7.1) MoAb. We found that spleen cells in the murine SS model treated with anti-CD86 MoAb showed a significant impairment of autoantigen-specific T cell proliferation. T cell activation markers (CD44high, CD45RBlow, Mel-14low) were significantly down-regulated in the spleen cells gated on CD4 in anti-CD86-treated mice. We detected a higher level of cytokine production of IL-4 from splenic T cells in anti-CD86-treated mice, but not of IL-2, and interferon-gamma (IFN-gamma), compared with those in the anti-CD80- and PBS-treated SS model. Moreover, serum autoantibody production against alpha-fodrin autoantigen was almost entirely suppressed in anti-CD86-treated mice. These data provide strong evidence that in autoimmune exocrinopathy resembling SS in NFS/sld mutant mice, the CD86 costimulatory molecule plays a crucial role in the initiation and subsequent progression of Th1-mediated autoimmunity in the salivary and lacrimal glands.

Involvement of apoptotic protease cascade for tissue destruction in Sjögren's syndrome.

Sjögren syndrome (SS) is an autoimmune disease characterized by diffuse lymphoid cell infiltrates in the salivary and lacrimal glands, resulting in symptoms of dry mouth and eyes due to insufficient secretion. Although it has been assumed that a combination of immunologic, genetic and environmental factors may play a key role in the development of autoimmune lesions in the salivary and lacrimal glands, little is known about the disease pathogenesis of SS in humans. We have identified the 120 kDa alpha-fodrin as an important autoantigen in the development of SS in both an animal model and SS patients, but the mechanism of alpha-fodrin cleavage leading to tissue destruction in SS remains unclear. Tissue-infiltrating CD4+ T cells purified from the salivary glands of a mouse model for SS bear a large proportion of Fas ligand and the salivary gland duct cells possess apoptotic receptor Fas. Anti-Fas antibody-induced apoptotic salivary gland cells result in specific alpha-fodrin cleavage to the 120 kDa fragment in vitro. Preincubation with a combination of calpain and caspase inhibitor peptides could be responsible for inhibition of the 120 kDa alpha-fodrin cleavage. Thus, an increase in apoptotic protease activities including calpain and caspases may be involved in the progression of alpha-fodrin proteolysis and tissue destruction in the development of SS.

Estrogen deficiency accelerates autoimmune exocrinopathy in murine Sjögren's syndrome through fas-mediated apoptosis.

Estrogenic action has been suggested to be responsible for the strong female preponderance of autoimmune diseases, but the role of estrogens in the female has not been well characterized. We evaluated the effects of estrogen deficiency in a murine model for autoimmune exocrinopathy of Sjögren's syndrome (SS). Severe destructive autoimmune lesions developed in the salivary and lacrimal glands in estrogen-deficient mice, and these lesions were recovered by estrogen administration. We detected an intense estrogen receptor in splenic CD8(+) T cells compared with that in CD4(+) T cells, and concanavalin-A-stimulated blastogenesis of splenic CD8(+) T cells with estrogens was much higher than that of CD4(+) T cells. We found a significant increase in serum autoantibody production against the organ-specific autoantigen alpha-fodrin. Moreover, an increased proportion of TUNEL+ apoptotic epithelial duct cells was observed in estrogen-deficient mice. It was demonstrated that Fas-mediated apoptosis in cultured salivary gland cells was clearly inhibited by estrogens in vitro. These results indicate that dysfunction of regulatory T cells by estrogen deficiency may play a crucial role on acceleration of organ-specific autoimmune lesions, and estrogenic action further influences target epithelial cells through Fas-mediated apoptosis in a murine model for SS.

Requirement for splenic CD4+ T cells in the immune privilege of the anterior chamber of the eye.

Injection of antigen into the anterior chamber of the eye induces suppression of antigen-specific DTH, called anterior chamber-associated immune deviation (ACAID). It has been shown that the spleen is required for the induction of ACAID and detecting the ACAID-inducing signal from the eye. To examine the in vivo role of spleen cells, fractions of spleen cells were adoptively transferred into splenectomized mice. The present study showed that DTH was not suppressed in splenectomized mice, but was inhibited in splenectomized mice transferred with a primed CD4+ T cell-containing fraction of spleen cells. This indicates that the splenic CD4+ T cells comprise the regulatory T cells for the DTH response. When we examined the cytokine profile of the infiltrating T cells in the eye of primed mice by reverse transcriptase-polymerase chain reaction (RT-PCR), we found that they expressed IL-4, IL-10 mRNA (Th2 type), but not IL-2 and interferon-gamma (IFN-gamma) mRNA (Th1 type). By contrast, T cells which can elicit normal DTH response expressed IL-2 and IFN-gamma mRNA. These results suggest that splenic CD4+ T cells comprising the regulatory phenotype are required for the induction of ACAID, and that a DTH response to the antigen may be prevented by Th2-dominant CD4+ T cells.

Anti-120-kDa alpha-fodrin immune response with Th1-cytokine profile in the NOD mouse model of Sjögren's syndrome.

Our recent study suggested that the 120-kDa alpha-fodrin molecule may be an important autoantigen in the pathogenesis of Sjögren's syndrome, and anti-120-kDa alpha-fodrin antibodies have been detected in patients with Sjögren's syndrome. Here we have analyzed anti-120-kDa alpha-fodrin immune responses during development of spontaneous autoimmune sialadenitis in NOD mice as a model of Sjögren's syndrome. We found specific autoantibody production against 120-kDa alpha-fodrin, and its production correlated closely with autoimmune sialadenitis. A specific T cell response of splenocytes against the 120-kDa alpha-fodrin autoantigen was observed in NOD mice from the early onset of autoimmune sialadenitis. In addition, production in vitro by splenic T cells of cytokines such as interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), but not IL-4, was detected by enzyme-linked immunosorbent assays. We found up-regulation of local cytokine genes, including those of Th1 type (IL-1beta, TNF-alpha, IL-2, IFN-gamma, IL-6), as well as IL-10 and IL-12(p40), in the tissue-infiltrating cells during the course of autoimmune sialadenitis. These findings suggest that in spontaneous autoimmune sialadenitis in NOD mice, there may be a specific anti-120-kDa alpha-fodrin immune response in the development of autoimmune lesions resembling human Sjögren's syndrome, and that the autoreactive Th1 cells possess an up-regulated cytokine profile besides IL-10 and IL-12.

Analysis of T cell receptor Vbeta usage in the autoimmune sialadenitis of non-obese diabetic (NOD) mice.

The NOD mouse develops spontaneous autoimmune sialadenitis besides a well characterized T cell-mediated autoimmune insulitis. We used reverse transcriptase-polymerase chain reaction (RT-PCR) to analyse the repertoire of T cell receptor (TCR) Vbeta chain genes expressed in the isolated infiltrating cells from affected salivary glands. Immunohistochemical analysis showed that the vast majority of inflammatory infiltrates in the salivary glands were CD4+ Vbeta8+ and CD4+ Vbeta6+ T cells, whereas CD8+ T cells and B220+ B cells were fewer in number. Predominant expression of the Vbeta8 and Vbeta6 gene segment was detected in the infiltrating cells in the salivary glands very early, and age-related diversity of TCR Vbeta gene usage was observed. Single-strand conformation polymorphism (SSCP) analysis demonstrated a strikingly symmetrical distribution of expanded clones in the PCR products of the Vbeta8 and Vbeta6 gene in the cells infiltrating the salivary glands. Nucleotide sequencing of amplified TCR Vbeta cDNA revealed that T cell clonotypes had a high incidence of identical clones, indicating that the immune response in NOD sialadenitis is driven by common stimuli. These findings suggest that in spontaneous autoimmune sialadenitis of NOD mice, there may be a restricted usage of TCR Vbeta elements in the early stage of the autoimmune lesion to recognize self-antigen in organ-specific autoimmune sialadenitis.

High incidence of autoimmune dacryoadenitis in male non-obese diabetic (NOD) mice depending on sex steroid.

The NOD mouse develops spontaneous autoimmune lesions in the lacrimal and salivary glands, besides a well characterized T cell-mediated autoimmune pancreatic beta cell lesion. We report unique pathological findings developed in the lacrimal glands as an autoimmune dacryoadenitis of NOD mice in contrast to those found in the salivary glands and pancreas. A high incidence of autoimmune lesions in the lacrimal glands was observed exclusively in male NOD mice at any age. Histology of autoimmune dacryoadenitis in male NOD mice showed severe destructive changes compared with those observed previously as an autoimmune lesion in the lacrimal glands. Castration in male NOD mice significantly decreased the incidence of autoimmune dacryoadenitis, and testosterone treatment with castration also increased the incidence of autoimmune lesions. Oestrogen treatment with castration did not increase the incidence, but tamoxifen treatment without castration significantly increased the incidence of autoimmune dacryoadenitis in NOD mice. In addition, we detected up-regulation of local cytokine genes (IL-1beta, tumour necrosis factor-alpha (TNF-alpha), IL-2, interferon-gamma (IFN-gamma), IL-6, IL-10, and IL-12 p40) during the course of autoimmune dacryoadenitis. These data suggest that in spontaneous autoimmune dacryoadenitis of male NOD mice there may be an intimate relationship with sex steroids, particularly testosterone, in the development and progression of autoimmune lesions, and autoreactive Th1 cells secrete up-regulated cytokine genes, including IL-10 and IL-12.

Identification of alpha-fodrin as a candidate autoantigen in primary Sjögren's syndrome.

It is unclear whether organ-specific autoantigens are critical for the development of primary Sjögren's syndrome (SS). A 120-kilodalton organ-specific autoantigen was purified from salivary gland tissues of an NFS/sld mouse model of human SS. The amino-terminal residues were identical to those of the human cytoskeletal protein alpha-fodrin. The purified antigen induced proliferative T cell responses and production of interleukin-2 and interferon-gamma in vitro. Neonatal immunization with the 120-kilodalton antigen prevented the disease in mice. Sera from patients with SS reacted positively with purified antigen and recombinant human alpha-fodrin protein, whereas those from patients with systemic lupus erythematosus and rheumatoid arthritis did not. Thus, the immune response to 120-kilodalton alpha-fodrin could be important in the initial development of primary SS.

Accelerated onset of age-related autoimmune lesions in MRL/+ mice by ovariectomy.

MRL/Mp +/+ (MRL/+) mice, not bearing the lpr gene, are known to have age-related autoimmune lesions in several organs such as pancreas, salivary and lacrimal glands at 30-weeks-old or more. In this study, MRL/+ mice were ovariectomized at 4-weeks-old, and their natural histories were analysed. Ovariectomy (Ovx) of MRL/+ mice led to marked acceleration of organ-specific autoimmune lesions exclusively in the salivary and lacrimal glands at 8-weeks-old or more, whereas no significant inflammatory change was observed in the pancreas. In the vast majority of inflammatory infiltrates, CD3+ CD4+ T cells were predominant in both the salivary and lacrimal glands of Ovx-MRL/+ mice. Up-regulated expression of cytokine genes including IL-1 beta, TNF-alpha, IL-2, interferon (IFN)-gamma, and IL-6 was detected in the salivary gland of Ovx-MRL/+ mice by reverse transcriptase (RT)-PCR analysis. FACS analysis of spleen cells of Ovx-mice revealed increase in I-Ak expression on B220+ cells, and autoantibody production against the salivary gland-specific antigen in sera from Ovx-MRL/+ mice, but not in control mice. These results suggest that age-related autoimmunity in the salivary and lacrimal glands were accelerated in Ovx-MRL/+ mice, and that autoreactive Th1 cells were activated associated with organ-specific autoantibody production.

Effector mechanism of experimental autoimmune sialadenitis in the mouse model for primary Sjögren's syndrome.

We have recently established a new animal model for primary Sjögren's syndrome in NFS/sld mutant mice thymectomized 3 days after birth (3dTX) bearing an autosomal recessive gene with sublingual gland differentiation arrest. In this study, we analyze developing mechanisms of experimental autoimmune sialadenitis (EAS) in the mouse model, focusing on local expressions of cytokine and cell adhesion molecule genes by reverse transcriptase-polymeric chain reaction (RT-PCR) and immunohistochemistry, kinetic analysis of splenic lymphocytes expressing activation markers, and I-Aq class-II molecules by flow cytometry (FACS). We found up-regulation of local cytokine genes (IL-1 beta, TNF-alpha, IL-2, IFN-gamma, IL-6, IL-10, IL-12p40) and cell adhesion molecule genes (ICAM-1, LFA-1, CD44, Mel-14) in the salivary glands from mice with EAS by RT-PCR, which were supported by immunohistochemistry. FACS analysis demonstrated that a significant proportion of splenic CD4+ T cells express activation markers (CD44, LFA-1, Mel-14low, CD45RB(low)) at a high level and an increase in expression of B220+ B cells bearing I-Aq class-II molecules. These data suggest that spontaneous EAS in 3dTX NFS/sld mutant mice may be triggered by an in situ activation of autoreactive CD4+ T cells comprising unique cytokine profile (high levels of IL-2, IFN-gamma, IL-10, and IL-12p40 mRNA) in the salivary glands.

Mechanism of the development of autoimmune dacryodenitis in the mouse model for primary Sjögren's syndrome.

To elucidate the mechanism of development in autoimmune lacrimal gland disease, we analyzed different aspects of autoimmune dacryoadenitis in a newly established mouse model for primary Sjögren's syndrome, focusing on the local expressions of cytokine genes, and the repertoire of T cell receptor (TCR) V beta genes transcribed within the inflammatory infiltration in the lacrimal glands. We found that the vast majority of inflammatory infiltration into the lacrimal glands were CD4+ V beta 8+ T cells. We detected the up-regulation of local cytokine genes (IL-1 beta, TNF-alpha, IL-2, IFN-gamma, IL-10, IL-12p40) in the lacrimal glands with very early inflammatory lesions by reverse transcriptase (RT)-PCR analysis. The predominant expression of the V beta 8 gene segment was detected from a very early stage, while extensive age-related diversity of TCR V beta gene usage was observed. Single-strand conformation polymorphism (SSCP) analysis demonstrated a distinct and a common binding pattern in the PCR product of the V beta 8 gene on the infiltrating cells during the course of the disease. These data suggest that in autoimmune dacryoadenitis of the mouse model for primary Sjögren's syndrome there may be a restricted usage of TCR V beta elements on a very early stage of the autoimmune lesion to recognize unknown self-antigen, and the autoreactive CD4+ T cells constitute a unique cytokine profile in the autoimmune lacrimal gland disease.

In vivo role of IL-10 and IL-12 during development of Sjögren's syndrome in MRL/lpr mice.

Expression of local cytokine genes including interleukin 10 (IL-10) and IL-12 was analyzed in the salivary gland tissues of MRL/lpr mice with Sjögren's syndrome. We demonstrate a significant role of IL-10 and IL-12 in vivo during development of Sjögren's syndrome in MRL/lpr mice. IL-10 mRNA expression was detected before the onset of disease and was upregulated during the course of autoimmune sialadenitis by RT-PCR. A predominant level of expression of IL-12 mRNA was also detected earlier in the proinflammatory stage of autoimmune sialadenities. Moreover, MHC class II (I-Ak) mRNA was detected before the onset of inflammatory lesions until older ages in the salivary glands of MRL/lpr mice. These results suggest that endogenous IL-10 and IL-12 may play important roles on immune-mediated destruction of the salivary glands during development of organ-specific autoimmunity in MRL/lpr mice.

Cytokine gene expression and autoantibody production in Sjögren's syndrome of MRL/lpr mice.

In an attempt to elucidate the mechanism of development of organ-specific autoimmune lesions resembling human Sjögren's syndrome of MRL/lpr mice, we have analyzed local cytokine gene expressions and organ-specific autoantibody production in vivo. We have demonstrated that a major proportion of T cells bearing CD4 and V(beta)8 molecules are essentially responsible for triggering the autoimmunity in the salivary glands of MRL/lpr mice. The local cytokine gene expressions including interferon(IFN)-gamma, IL-12(p40) mRNAs were observed during the course of murine Sjogren's syndrome in MRL/lpr autoimmune strain. In particular, a high level of local expressions of IL-12 mRNA was detected earlier in the proinflammatory stage of autoimmune lesions. A significant level of local expression of MHC class-II(I-Ak) mRNA was detected before the onset of inflammatory lesions in the salivary glands, and I-Ak-positive epithelial duct cells were frequently observed in the salivary glands of MRL/lpr mice. In addition, we found the salivary gland-specific autoantibody in sera from MRL/lpr mice with early phase of autoimmune lesions by immunoblot analysis. These results suggest that cytokine gene stimulation and autoantibody production are essentially involved in the development of organ-specific autoimmune lesions in Sjögren's syndrome of MRL/lpr mice.

Immunopathological analysis of mucosal melanocyte distribution in the human lower lip of the elderly.

Mucosal melanocyte distribution in the human lower lip was analyzed immunopathologically using a wide selection of 195 surgical specimens. An age-related increase of mucosal melanocyte distribution was observed in the human lower lip by Fontana-Masson argentaffin stain and S-100 protein immunoreactivity. The mean number of mucosal melanocytes increased gradually with advancing age. A large number of them was found at or beyond the seventh decade of life in both sexes, which was statistically significant compared with those in all other decades (p < 0.01 or < 0.05). In addition, the sex difference in mucosal melanocyte density was statistically significant (p < 0.001) in each decade (men > women). These results suggest that physiological changes in mucosal melanocyte distribution are dependent upon aging and sex difference, and may play an important role in development of melanocytic lesions such as senile lentigo, pigmented nevi, and also intraepithelial malignant melanomas.

Expression of HLA-DR and cytokine genes on interferon-gamma-stimulated human salivary gland cell line.

Stimulation of a cultured human salivary gland (HSG) cell line by interferon (IFN)-gamma leads to HLA-DR gene expression concomitant with inflammatory cytokine genes such as IL-1 beta, tumor necrosis factor (TNF)-alpha, and IL-6 in vitro. IFN-gamma-induced HLA-DR mRNA expression was clearly detected at 2 h after the stimulation, and thereafter its level of gene expression increased until day 7 on HSG cells by reverse transcriptase (RT)-PCR. Immunofluorescence analysis revealed that cytoplasmic HLA-DR immunoreactivity was detected for the first time at 2 days after the stimulation, and its immunoreactivity increased gradually until day 7, while no immunoreactivity with HLA-DP and HLA-DQ was observed at any of the days. In addition, the expression of IL-1 beta, TNF-alpha, and IL-6 on the IFN-gamma-stimulated HSG cells was detected by immunohistochemistry and RT-PCR analysis. These results indicate that human salivary gland cells can be induced to express HLA-DR mRNA by IFN-gamma concomitant with inflammatory cytokine gene expressions such as IL-1 beta, TNF-alpha, and IL-6.

Prevention of adoptive transfer of murine Sjögren's syndrome into severe combined immunodeficient (SCID) mice by antibodies against intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1).

We have analysed the role of ICAM-1 and LFA-1 during development of autoimmune sialadenitis in MRL/lpr mice by direct analysis of RNA obtained from the salivary gland tissues, and the therapeutic effects with antibody administration on adoptive transfer system into SCID mice. The expression of cell adhesion molecules was assessed by using reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot analysis, and immunohistochemical analysis. Up-regulated expression of ICAM-1 mRNA was observed before the onset of inflammatory lesions in the salivary glands at 1 month and 2 months old, and thereafter LFA-1 mRNA was expressed within the typical inflammatory lesions, resembling human Sjögren's syndrome in MRL/lpr mice. Immunohistochemically, ICAM-1 was localized exclusively in the endothelial cells of varying sized blood vessels before the onset of disease, and LFA-1 expressing inflammatory cells were found within these lesions. When the therapeutic effects in vivo were examined, antibodies to ICAM-1 in combination with anti-LFA-1 prevented adoptive transfer of Sjögren's syndrome in MRL/lpr mice into SCID mice, while no significant effect was found when treated with either antibody. These findings indicate that in Sjögren's syndrome-like autoimmune lesions in MRL/lpr mice the ICAM-1/LFA-1 pathway may play a crucial role in the initiation and subsequent progression of T cell-mediated autoimmunity in the salivary and lacrimal glands of MRL/lpr mice.