IL-33 Orchestrated the Interaction and Immunoregulatory Functions of Alternatively Activated Macrophages and Regulatory T Cells In Vitro.

Our group has previously demonstrated elevated serum-soluble ST2 in patients with active systemic lupus erythematosus, suggesting a role of IL-33 in the underlying pathogenesis. However, inconsistent results have been reported on the effect of exogenous IL-33 on murine lupus activity, which may be mediated by concerted actions of various immune cells in vivo. This study aimed to examine the function of IL-33 on macrophage polarization and regulatory T cells (Treg) and their interactive effects in the lupus setting by in vitro coculture experiments of macrophages and T cells that were performed in the presence or absence of IL-33-containing medium. Compared to IL-4-polarized bone marrow-derived macrophages (BMDM) from MRL/MpJ mice, adding IL-33 enhanced mRNA expression of markers of alternatively activated macrophages, including CD206 and Arg1. IL-33 and IL-4 copolarized BMDM produced higher TGF-ß but not IL-6 upon inflammatory challenge. These BMDM induced an increase in the Foxp3+CD25+ Treg population in cocultured allogeneic T cells from MRL/MpJ and predisease MRL/lpr mice. These copolarized BMDM also showed an enhanced suppressive effect on T cell proliferation with reduced IFN-γ and IL-17 release but increased TGF-ß production. In the presence of TGF-ß and IL-2, IL-33 also directly promoted inducible Treg that expressed a high level of CD25 and more sustained Foxp3. Unpolarized BMDM cocultured with these Treg displayed higher phagocytosis. In conclusion, TGF-ß was identified as a key cytokine produced by IL-4 and IL-33 copolarized alternatively activated macrophages and the induced Treg, which may contribute to a positive feedback loop potentiating the immunoregulatory functions of IL-33.

Interleukin-33 Ameliorates Murine Systemic Lupus Erythematosus and Is Associated with Induction of M2 Macrophage Polarisation and Regulatory T Cells.

The innate cytokine IL-33 is increasingly recognised to possess biological effects on various immune cells. We have previously demonstrated elevated serum level of soluble ST2 in patients with active systemic lupus erythematosus suggesting involvement of IL-33 and its receptor in the lupus pathogenesis. This study sought to examine the effect of exogenous IL-33 on disease activity of pre-disease lupus-prone mice and the underlying cellular mechanisms. Recombinant IL-33 was administered to MRL/lpr mice for 6 weeks, whereas control group received phosphate-buffered saline. IL-33-treated mice displayed less proteinuria, renal histological inflammatory changes, and had lower serum levels of pro-inflammatory cytokines including IL-6 and TNF-α. Renal tissue and splenic CD11b+ extracts showed features of M2 polarisation with elevated mRNA expression of Arg1, FIZZI, and reduced iNOS. These mice also had increased IL-13, ST2, Gata3, and Foxp3 mRNA expression in renal and splenic tissues. Kidneys of these mice displayed less CD11b+ infiltration, had downregulated MCP-1, and increased infiltration of Foxp3-expressing cells. Splenic CD4+ T cells showed increased ST2-expressing CD4+Foxp3+ population and reduced IFN-γ+ population. There were no differences in serum anti-dsDNA antibodies and renal C3 and IgG2a deposit in these mice. Exogenous IL-33 was found to ameliorate disease activity in lupus-prone mice with induction of M2 polarisation, Th2 response, and expansion of regulatory T cells. IL-33 likely orchestrated autoregulation of these cells through upregulation of ST2 expression.

Severe Periodontitis Is a Major Contributory Factor to Unmet Dental Healthcare Needs among Rheumatoid Arthritis Patients in Hong Kong.

Objective: This study aimed to examine the frequency and predictive factors of adverse oral and dental outcomes in patients with rheumatoid arthritis (RA) with the goal to address their unmet dental healthcare needs in the metropolitan city of Hong Kong. Methods: 238 RA patients followed up at local public hospitals were recruited in this cross-sectional study. A full dental examination was performed. Data were compared with the retrospective data collected from age-matched control groups in the community conducted in a territory-wide oral health survey in 2011. Predictive factors for severe periodontitis including various demographic and disease-specific factors were examined by multiple logistic regression analysis. Results: Loose teeth and gum bleeding were frequent dental complaints. Only 85.0% of RA patients had >20 natural teeth. Total edentulism was observed in 3.8% of patients, which was higher among adult (22-64 years) and elderly (>65 years old) RA patients than their respective age-matched community control groups. RA patients had a higher decayed, missing, and filled tooth score. Adult RA patients had a 5.3-fold increase in risk of severe periodontitis than their community counterparts. The plaque index was the main predisposing factor for severe periodontitis (odds ratio 17.5, p=0.001), which was worse among the 22-34 age group of patients. More RA patients required tooth extraction compared to dental filling for their community controls. Conclusion: Severe periodontitis is a major cause of unmet dental healthcare needs among RA patients in Hong Kong. It is recommended that dental care plans for RA patients be commenced early among newly diagnosed patients.