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Recent studies implicate innate immunity to systemic lupus erythematosus (SLE) pathogenesis. Toll-like receptor (TLR)8 is estrogen-regulated and binds viral ssRNA to stimulate innate immune responses, but recent work indicates that microRNA (miR)-21 within extracellular vesicles (EVs) can also trigger this receptor. Our objective was to examine TLR8 expression/activation to better understand sex-biased responses involving TLR8 in SLE. Our data identify an estrogen response element that promotes STAT1 expression and demonstrate STAT1-dependent transcriptional activation of TLR8 with estrogen stimulation. In lieu of viral ssRNA activation, we explored EV-encapsulated miR-21 as an endogenous ligand and observed induction of both TLR8 and cytokine expression in vitro. Moreover, extracellular miR detection was found predominantly within EVs. Thus, just as a cytokine or chemokine, EV-encapsulated miR-21 can act as an inflammatory signaling molecule, or miRokine, by virtue of being an endogenous ligand of TLR8. Collectively, our data elucidates a novel innate inflammatory pathway in SLE.

Since being discovered over half a century ago, mesenchymal stem cells (MSCs) have been investigated extensively to characterize their cellular and physiological influences. MSCs have been shown to possess immunosuppressive capacity through inhibiting lymphocyte activation/proliferation and proinflammatory cytokine secretion while simultaneously demonstrating limited allogenic reactivity, which subsequently led to the evaluation of therapeutic feasibility to treat inflammatory diseases. Although regulatory constraints have restricted MSC development pharmacologically, limited clinical studies have shown encouraging results using MSC infusions to treat systemic lupus erythematosus (SLE); but, more trials will have to be performed to conclusively determine the clinical efficacy of MSCs to treat SLE. Moreover, there are some data to suggest that MSCs possess tumorigenic potential and that the immunosuppressive influence can be dramatically affected by both donor variability and ex vivo expansion. Given that recent studies have found that the immunosuppressive effects of MSCs are a result, at least in part, to extracellular vesicle (EV) secretion, the use of MSC-derived EVs has been suggested as a cell-free therapeutic alternative. Despite the positive data observed using EVs isolated from human MSCs to suppress inflammatory responses in vitro and in inhibiting autoimmune disease pathogenesis in preclinical work, there are no studies to date examining EVs from MSCs to treat SLE in humans or animal models. Considering that EVs are not subject to the strict regulatory constraints of stem cell-based pharmacological development and are more readily standardized with regard to industrial-scale production and storage, this review outlines the anti-inflammatory biology of MSCs and the scientific evidence supporting the potential use of EVs derived from human MSCs to treat patients with SLE.

Background and aims We have previously demonstrated that toll-like receptor (TLR)7 and TLR8 are significantly up-regulated in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus (SLE) patients and can be further induced with oestrogen treatment. It has recently been shown that specific micro-RNA (miR) sequences packaged in extracellular vesicles can stimulate these receptors in addition to the conventional activation by binding single-stranded RNA of viral origin. The aim of this study was to explore the feasibility of using miR antagonists to block TLR7 and TLR8-mediated inflammatory pathways. Methods Human-mouse chimaeras were generated by adoptively transferring PBMCs from active SLE patients into immunodeficient NOD-scid IL-2rγ (null) mice using a modified protocol that we previously established in Sjojren’s syndrome. Prior to transfer, SLE patient PBMCs were treated either with a cocktail of locked nucleic acid antagonists targeting several miRs or nonsense, scrambled controls. At 21 days post-transfer, blood was collected for flow cytometry and cytokine analysis; tissues were processed for histopathological examination by H and E and immunohistochemistry. Results The phenotypic characteristics of various immune cells were similar in both experimental groups; however, inhibition with miR antagonists reduced levels of human IL-2, IL-6, IL-10, and TNF-α relative to scramble (control) treatment. Histopathological analysis revealed that miR antogonists inhibited the robust responses detected with control treatment in the small intestine, liver, and kidney. Further characterisation of infiltrates confirmed the presence human CD3+ T-cells. Conclusions These data establish a novel model to study SLE and provide experimental evidence that TLR7 and TLR8 targeted miR antagonists have therapeutic potential in SLE.

Despite the widespread use of curcumin for centuries in Eastern medicine as an anti-inflammatory agent, its molecular actions and therapeutic viability have only recently been explored. While curcumin does have potential therapeutic efficacy, both solubility and bioavailability must be improved before it can be more successfully translated to clinical care. We have previously reported a novel formulation of nano-emulsion curcumin (NEC) that achieves significantly greater plasma concentrations in mice after oral administration. Here, we confirm the immunosuppressive effects of NEC in vivo and further examine its molecular mechanisms to better understand therapeutic potential. Using transgenic mice harboring an NFκB-luciferase reporter gene, we demonstrate a novel application of this in vivo inflammatory model to test the efficacy of NEC administration by bioluminescent imaging and show that LPS-induced NFκB activity was suppressed with NEC compared to an equivalent amount of curcumin in aqueous suspension. Administration of NEC by oral gavage resulted in a reduction of blood monocytes, decreased levels of both TLR4 and RAGE expression, and inhibited secretion of MCP-1. Mechanistically, curcumin blocked LPS-induced phosphorylation of the p65 subunit of NFκB and IκBα in murine macrophages. In a mouse model of peritonitis, NEC significantly reduced macrophage recruitment, but not T-cell or B-cell levels. In addition, curcumin treatment of monocyte derived cell lines and primary human macrophages in vitro significantly inhibited cell migration. These data demonstrate that curcumin can suppress inflammation by inhibiting macrophage migration via NFκB and MCP-1 inhibition and establish that NEC is an effective therapeutic formulation to increase the bioavailability of curcumin in order to facilitate this response.

Background Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease affecting multiple organs and displaying a heavy female predominance during reproductive years. Our previous studies have demonstrated that toll-like receptor (TLR)7 and TLR8 are significantly up-regulated in peripheral blood mononuclear cells (PBMCs) of SLE patients and induced with estrogen treatment. While the conventional role of TLR7 and TLR8 involves binding to single-stranded RNA of viral origin to stimulate innate inflammatory responses, recent work has identified specific micro-RNAs (miRs) capable of activating these receptors that are packaged and secreted in exosomes. Objectives The goal of this study was to explore the therapeutic potential of using a cocktail of miR antagonists to block TLR7 and TLR8 inflammatory pathways induced by extracellular vesicle (EV)-derived miRs in SLE. Methods PBMCs from active SLE patients were adoptively transferred into immunodeficient NOD-scid IL-2rγ (null) mice to produce chimeras using a similar protocol we have previously established for Sjojren9s syndrome. PBMCs were treated with a cocktail of locked nucleic acid miR antagonists or nonsense, scrambled RNA control prior to injection. Blood was collected for both flow cytometry and cytokine analysis and tissues were processed for histopathological examination by H&E and immunohistochemistry. Results 21 days after adoptive transfer, human T-cells (CD4+ and CD8+), B-cells, monocytes, and NK cells were all successfully recovered from whole blood of chimeric mice at similar levels in both treatment groups. However, miR inhibition reduced levels of human IL-2, IL-6, IL-10, and TNF-α when compared to scramble (control) treatment. Although histopathological analysis revealed little to no inflammation in the skin and ear, miR inhibition blocked the robust responses detected in the small intestine, liver, and kidney with scramble RNA (control) treatment. Immunohistochemical analysis of the infiltrates confirmed the presence human CD3+ T-cells in these tissues and further demonstrated the suppression of inflammation following miR inhibition. Conclusions These results establish a novel chimeric model to study SLE and provide a platform to further explore the therapeutic efficacy of suppressing EV-encapsulated miRs that bind to TLR7 and TLR8 to induce autoimmune-mediated inflammatory responses. References Fabbri M, Paone A, Calore F, Galli R, Gaudio E, Santhanam R, et al. MicroRNAs bind to Toll-like receptors to induce prometastatic inflammatory response. Proceedings of the National Academy of Sciences of the United States of America 2012, 109(31): E2110–2116. Young NA, Wu LC, Burd CJ, Friedman AK, Kaffenberger BH, Rajaram MV, et al. Estrogen modulation of endosome-associated toll-like receptor 8: an IFNalpha-independent mechanism of sex-bias in systemic lupus erythematosus. Clinical immunology 2014, 151(1): 66–77. Young NA, et al. A chimeric human-mouse model of Sjogren9s syndrome. Clinical immunology, 2014;156:1–8. Acknowledgement We would like to extend our appreciation to all the volunteers that participated in this study and thank the Center for Clinical and Translational Science/Research Match program at The Ohio State University Wexner Medical Cetner and the American Red Cross. Disclosure of Interest None declared

Background Studies incorporating either regular exercise or stress modification programs have been efficacious in influencing the clinical disease course of systemic lupus erythematosus (SLE). We have previously demonstrated in mice that daily, moderate exercise limits inflammation systemically and that repeated social stress stimulates proinflammatory responses. Objectives To determine if daily moderate exercise (DME) or psychosocial stress can significantly affect chronic autoimmune-mediated inflammation, we examined the NZM2410 mouse model of lupus nephritis, which spontaneously develops severe, early-onset glomerulonephritis at 22–40 weeks of age. Methods All mice were removed from the study when experimental removal criteria was reached [blood urea nitrogen (BUN)>50 μg/mL; weight loss>20%]. The DME protocol consisted of daily 45 min treadmill walks at moderate intensity (8 m/min) beginning at 18 weeks of age. To disturb the social order within an established social hierarchy, an aggressive intruder was introduced to induce repeated social disruption stress (SDR). SDR was performed daily for 6 consecutive days beginning at 20 weeks of age. When SDR mice met experimental removal criteria, an age-matched control counterpart was selected at random for comparative analysis. Kidney tissue and serum were collected at experimental endpoint. Multi-plex ELISA measurements of cytokine expression were performed on serum samples. Results Glomerulonephritis was enhanced with SDR, but significantly improved with DME, as indicated by IgG and C3 complex deposition. Histopathological examination of renal tissue showed glomerular hypercellularity and hyperplasia of the Bowman9s capsule. Furthermore, BUN and weight measurements showed a 42% improvement with DME at 43 weeks of age. Immunohistochemical analysis and digital image quantitation of macrophage-mediated inflammatory responses in the kidney revealed a significant induction with SDR and suppression with DME. Additionally, serum cytokine analysis showed up-regulation of IL-5, IL-6, IL-10, and TNF-α with SDR and in older NZM2410 mice relative to younger mice and wild-type controls. While levels of IL-6 were not reduced, expression of IL-5, IL-10, and TNF-α was suppressed with DME. Since TNF-α induces monocyte chemoattractant protein-1 (MCP-1) secretion, MCP-1 expression was measured and demonstrated a reduction with DME and enhancement following SDR. Conclusions Our data suggests that renal histopathology can be modified via exercise and stress reduction by suppressing TNF-α induction and expression of MCP-1. Thus, stress reduction and moderate exercise could be used therapeutically in adjunct to pharmacological therapy to help control the chronic inflammation associated with lupus nephritis and other autoimmune diseases. References Blazek, A, et al. Exercise Suppresses Systemic Inflammation via Inhibition of Nf-Kb Activation in Monocytes. Ann Rheum Dis 2014;73:Suppl 2 102 doi:10.1136/annrheumdis-2014-eular.3914 Powell, ND, et al., Social stress up-regulates inflammatory gene expression in the leukocyte transcriptome via beta-adrenergic induction of myelopoiesis. Proc Natl Acad Sci U S A, 2013. 110(41): p. 16574–9. Acknowledgement The Ohio State University Wexner Medical Center Disclosure of Interest None declared