Shinji Ono's research while affiliated with The University of Tokushima and other places

Aim Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease that affects exocrine glands. CXCL10 production from salivary gland ductal cells via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway has been suggested to be involved in glandular inflammation in pSS. We aimed to investigate JAK1, JAK2, phosphorylated JAK1, and phosphorylated JAK2 expression in labial salivary gland (LSG) tissues from patients with pSS to evaluate the potential of JAK inhibitors as therapeutic agents for pSS. Methods Immunohistochemical analysis was performed using LSG tissues of patients with pSS (n = 10), non‐SS patients (n = 5), and healthy controls (n = 5). The LSG sections were scored to determine the expression levels of JAK1, JAK2, phosphorylated JAK1, and phosphorylated JAK2 in the ductal and acinar epithelium. Results In acinar epithelial cells of LSG tissues, JAK1, JAK2, and phosphorylated JAK1 expression was significantly lower in patients with pSS than in the controls. Significantly high expression of phosphorylated JAK1 and phosphorylated JAK2 was observed in the ductal epithelial cells of patients with pSS. However, there was no significant association between phosphorylated JAK1 or JAK2 expression levels and inflammation degree. Furthermore, immunofluorescence analysis revealed JAK2 phosphorylation in many CD3 ⁺ T cells infiltrating the LSG tissues. Conclusions The results suggest JAK2 activation in both ductal epithelial cells and infiltrating CD3 ⁺ T cells in LSG tissues of patients with pSS. JAK inhibitors may be effective therapeutic agents for pSS by regulating both chemokine production from salivary gland cells and effector T cell activation.

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease that affects exocrine glands, such as salivary and lacrimal glands. The Janus kinase (JAK) /signal transducer and activator of transcription (STAT) pathway are activated in various inflammatory diseases including pSS. This study aimed to investigate the expression of JAK1, JAK2, phosphorylated JAK1, and phosphorylated JAK2 in labial salivary gland (LSG) tissues from patients with pSS to evaluate the potential of JAK inhibitors as therapeutic agents for pSS. Immunohistochemical analysis was performed using LSG tissues of patients with pSS (n=10), non-SS (n=5), and healthy controls (n=5). In acinar epithelial cells, JAK1, JAK2, and phosphorylated JAK1 were expressed at significantly lower levels in LSG tissues of patients with pSS than in healthy controls. Significantly higher expression of phosphorylated JAK1 and phosphorylated JAK2 was observed in the ductal epithelial cells of patients with pSS compared to the controls. However, there was no significant association between the expression levels of phosphorylated JAK1 or JAK2 and the degree of inflammation. In addition, immunofluorescence analysis revealed JAK2 phosphorylation in many CD3 + T cells infiltrating the LSG tissues. These results suggested the activation of JAK/STAT signaling in both the ductal epithelial cells and the infiltrating CD3 + T cells in the LSG tissues of patients with pSS. Therefore, JAK inhibitors may be effective therapeutic agents for pSS by regulating both effector T cells and target cells.

Sjögren’s syndrome (SS) is a chronic autoimmune disease targeting salivary and lacrimal glands. C-X-C motif chemokine ligand 10 (CXCL10) expression is upregulated in lip salivary glands (LSGs) of primary SS (pSS) patients, and CXCL10 involved in SS pathogenesis via immune-cell accumulation. Moreover, interferon (IFN)-γ enhances CXCL10 production via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. We investigated the effects of baricitinib, a selective JAK1/2 inhibitor, on both IFN-γ-induced CXCL10 production and immune-cell chemotaxis. We used immunohistochemical staining to determine the expression levels and localization of JAK1 and JAK2 in LSGs of SS patients (n = 12) and healthy controls (n = 3). We then evaluated the effect of baricitinib in an immortalized normal human salivary gland ductal (NS-SV-DC) cell line. Immunohistochemical analysis of LSGs from pSS patients revealed strong JAK1 and JAK2 expression in ductal and acinar cells, respectively. Baricitinib significantly inhibited IFN-γ-induced CXCL10 expression as well as the protein levels in an immortalized human salivary gland ductal-cell clone in a dose-dependent manner. Additionally, western blot analysis showed that baricitinib suppressed the IFN-γ-induced phosphorylation of STAT1 and STAT3, with a stronger effect observed in the case of STAT1. It also inhibited IFN-γ-mediated chemotaxis of Jurkat T cells. These results suggested that baricitinib suppressed IFN-γ-induced CXCL10 expression and attenuated immune-cell chemotaxis by inhibiting JAK/STAT signaling, suggesting its potential as a therapeutic strategy for pSS.

Gene expression profiling of lip salivary gland (LSG) has shown that C-X-C motif chemokine 10 (CXCL10) and matrix metalloproteinase 9 (MMP9) expression is upregulated in primary Sjögren’s syndrome (pSS) patients. Although CXCL10 and MMP-9 are both associated with pSS pathogenesis, the potential relationship between these two factors has not been investigated. In this study, we used LSG sections from pSS patients and human salivary gland cell lines to investigate the relationship between CXCL10 and MMP-9. Immunofluorescence analyses revealed that CXCL10 and MMP-9 were co-expressed in the LSG of pSS patients, particularly in expanded ductal cells. Furthermore, RT-qPCR analyses on human salivary gland ductal NS-SV-DC cells confirmed that CXCL10 expression was induced by interferon (IFN)-γ, whereas that of MMP9 was stimulated by IFN-α, tumor necrosis factor-α, and interleukin-1β. Remarkably, MMP-9 inhibition in IFN-γ-stimulated NS-SV-DC cells significantly decreased CXCL10 mRNA and secreted protein levels. Further analyses established that MMP-9 inhibition in IFN-γ-stimulated NS-SV-DC cells decreased STAT1 phosphorylation and hence suppressed IFN-γ signaling. Collectively, these results suggest that in addition to its reported role in the destruction of acinar structures, MMP-9 is involved in the IFN-γ-induced production of CXCL10 in pSS lesions. We believe that our findings open the door to the development of novel treatments for pSS, based on the modulation of MMP-9 activity.