Renxi Wang

Interleukin-35 induces regulatory B cells that suppress autoimmune disease

Interleukin-10 (IL-10)-producing regulatory B (Breg) cells suppress autoimmune disease, and increased numbers of Breg cells prevent host defense to infection and promote tumor growth and metastasis by converting resting CD4+ T cells to regulatory T (Treg) cells. The mechanisms mediating the induction and development of Breg cells remain unclear. Here we show that IL-35 induces Breg cells and promotes their conversion to a Breg subset that produces IL-35 as well as IL-10. Treatment of mice with IL-35 conferred protection from experimental autoimmune uveitis (EAU), and mice lacking IL-35 (p35 knockout (KO) mice) or defective in IL-35 signaling (IL-12Rβ2 KO mice) produced less Breg cells endogenously or after treatment with IL-35 and developed severe uveitis. Adoptive transfer of Breg cells induced by recombinant IL-35 suppressed EAU when transferred to mice with established disease, inhibiting pathogenic T helper type 17 (TH17) and TH1 cells while promoting Treg cell expansion. In B cells, IL-35 activates STAT1 and STAT3 through the IL-35 receptor comprising the IL-12Rβ2 and IL-27Rα subunits. As IL-35 also induced the conversion of human B cells into Breg cells, these findings suggest that IL-35 may be used to induce autologous Breg and IL-35+ Breg cells and treat autoimmune and inflammatory disease.

Novel IL27p28/IL12p40 cytokine suppressed experimental autoimmune uveitis by inhibiting autoreactive Th1/Th17 cells and promoting expansion of regulatory T cells.

Background: We genetically engineered a novel IL27p28/IL12p40 cytokine and examined its use in treatment of uveitis. Results: IL27p28/IL12p40 ameliorated uveitis by inhibiting the differentiation and activation of Th1 and Th17 lymphocytes. Conclusion: IL27p28/IL12p40 can potentially be used to treat CNS autoimmune diseases like uveitis. Significance: This proof-of-concept experiment suggests that novel combinations of α/β IL12 subunits may constitute a new class of therapeutic cytokines. IL-12 family cytokines are important in host immunity. Whereas some members (IL-12, IL-23) play crucial roles in pathogenesis of organ-specific autoimmune diseases by inducing the differentiation of Th1 and Th17 lymphocytes, others (IL-27 and IL-35) suppress inflammatory responses and limit tissue injury induced by these T cell subsets. In this study, we have genetically engineered a novel IL27p28/IL12p40 heterodimeric cytokine (p28/p40) that antagonizes signaling downstream of the gp130 receptor. We investigated whether p28/p40 can be used to ameliorate uveitis, a CNS inflammatory disease. Experimental autoimmune uveitis (EAU) is the mouse model of human uveitis and is mediated by Th1 and Th17 cells. We show here that p28/p40 suppressed EAU by inhibiting the differentiation and inflammatory responses of Th1 and Th17 cells while promoting expansion of IL-10+- and Foxp3+-expressing regulatory T cells. Lymph node cells from mice treated with p28/p40 blocked adoptive transfer of EAU to naïve syngeneic mice by immunopathogenic T cells and suppressive effects of p28/p40 derived in part from antagonizing STAT1 and STAT3 pathways induced by IL-27 and IL-6. Interestingly, IL27p28 also suppressed EAU, but to a lesser extent than p28/p40. The inhibition of uveitogenic lymphocyte proliferation and suppression of EAU by p28/p40 and IL27p28 establish efficacy of single chain and heterodimeric IL-12 family cytokines in treatment of a CNS autoimmune disease. Creation of the biologically active p28/p40 heterodimeric cytokine represents an important proof-of-concept experiment, suggesting that cytokines comprising unique IL-12 α- and β-subunit pairing may exist in nature and may constitute a new class of therapeutic cytokines.

Interleukin 35: Critical regulator of immunity and lymphocyte-mediated diseases.

Cytokines coordinate the activities of innate and adaptive immune systems and the Interleukin 12 (IL-12) family of cytokines has emerged as critical regulators of immunity in infectious and autoimmune diseases. While some members (IL-12 and IL-23) are associated with the pathogenesis of chronic inflammatory diseases, others (IL-27 and IL-35) mitigate autoimmune diseases. Unlike IL-12, IL-23 and IL-27 that are produced mainly by antigen presenting cells, IL-35 is predominantly secreted by regulatory B (i35-Bregs) and T (iTR35) cells. The discovery that IL-35 can induce the conversion or expansion of lymphocytes to regulatory B and T cells has considerable implications for therapeutic use of autologous regulatory B and T cells in human diseases. Although our current understanding of the immunobiology of IL-35 or its subunits (p35 and Ebi3) is still rudimentary, our goal in this review is to summarize what we know about this enigmatic cytokine and its potential clinical use, particularly in the treatment of CNS autoimmune diseases.

A novel IL-23p19/Ebi3 (IL-39) cytokine mediates inflammation in Lupus-like mice.

Interleukin‐12 family cytokines have emerged as critical regulators of immunity with some members (IL‐12, IL‐23) associated with disease pathogenesis while others (IL‐27, IL‐35) mitigate autoimmune diseases. Each IL‐12 family member is comprised of an α and a β chain, and chain‐sharing is a key feature. Although four bona fide members have thus far been described, promiscuous chain‐pairing between alpha (IL‐23p19, IL‐27p28, IL‐12/IL‐35p35) and beta (IL‐12/IL‐23p40, IL‐27/IL‐35Ebi3) subunits, predicts six possible heterodimeric IL‐12 family cytokines. Here, we describe a new IL‐12 member composed of IL‐23p19 and Ebi3 heterodimer (IL‐39) that is secreted by LPS‐stimulated B cells and GL7+ activated B cells of lupus‐like mice. We further show that IL‐39 mediates inflammatory responses through activation of STAT1/STAT3 in lupus‐like mice. Taken together, our results show that IL‐39 might contribute to immunopathogenic mechanisms of systemic lupus erythematosus, and could be used as a possible target for its treatment.

IL-12p35 induces expansion of IL-10 and IL-35-expressing regulatory B cells and ameliorates autoimmune disease

Interleukin 35 (IL-35) is a heterodimeric cytokine composed of IL-12p35 and Ebi3 subunits. IL-35 suppresses autoimmune diseases while preventing host defense to infection and promoting tumor growth and metastasis by converting resting B and T cells into IL-10-producing and IL-35-producing regulatory B (Breg)xa0and T (Treg)xa0cells. Despite sharing the IL-12p35 subunit, IL-12 (IL-12p35/IL-12p40) promotes inflammatory responses whereas IL-35 (IL-12p35/Ebi3) induces regulatory responses, suggesting that IL-12p35 may have unknown intrinsic immune-regulatory functions regulated by its heterodimeric partner. Here we show that the IL-12p35 subunit has immunoregulatory functions hitherto attributed to IL-35. IL-12p35 suppresses lymphocyte proliferation, induces expansion of IL-10-expressing and IL-35-expressing B cells and ameliorates autoimmune uveitis in mice by antagonizing pathogenic Th17 responses. Recapitulation of essential immunosuppressive activities of IL-35 indicates that IL-12p35 may be utilized for in vivo expansion of Breg cells and autologous Breg cell immunotherapy. Furthermore, our uveitis data suggest that intrinsic immunoregulatory activities of other single chain IL-12 subunits might be exploited to treat other autoimmune diseases.IL-12p35 is common to IL-35 and IL-12, which have opposing effects on inflammation. Here the authors show that the IL-12p35 subunit induces regulatory B cells and can be used therapeutically to limit autoimmune uveitis in mice.

Pre-existing CD19-independent GL7− Breg cells are expanded during inflammation and in mice with lupus-like disease

Interleukin 10 (IL-10)-producing regulatory B-cells (Bregs) suppress inflammatory responses that mediate autoimmune diseases. However, it is unknown whether Bregs derive from a pre-existing dedicated B-cell lineage or if any B-cell can differentiate into Bregs in response to BCR or TLR activation. GL7(+) B-cells are antigen-experienced differentiated B-cells while GL7(-/lo) are at an early stage of B-cell differentiation. While both GL7(-/lo) and GL7(+) B cells can produce IL-10, differentiation of GL7(-) B-cells into Bregs does not require CD19- or Bcl6-induced signals, suggesting that BCR-induced proliferation or Ig class-switching is not necessary for generation of Breg cells. Of particular importance, we show that GL7(-) Breg cells are dramatically expanded in lupus-like mice and GL7(-) Bregs suppressed inflammatory responses in lupus-like mice by inducing expansion of Foxp3(+)Treg cells. Taken together, these results suggest that pre-existing GL7(-)IL-10(+) cells are expanded during inflammation, differentiate into GL7(+) Bregs and contribute to immune-regulation in lupus-like mice.

B cell activating factor (BAFF) selects IL-10−B cells over IL-10+B cells during inflammatory responses

&NA; B cell activating factor (BAFF) regulates B cell maturation, survival, function, and plays a critical pathogenic role in autoimmune diseases. It remains unclear how BAFF affects IL‐10−B cells versus regulatory B cells (Bregs) in inflammatory responses. In this study, we found that IL‐10‐expressing Bregs decreased in lupus‐prone MRL/lpr mice and experimental allergic encephalomyelitis (EAE) mice. On blockade of the effects of BAFF with TACI‐IgG, IL‐10+ Bregs were upregulated in MRL/lpr and EAE mice. In addition, BAFF expanded IL‐10+B cells over IL‐10−B cells under noninflammatory conditions in vitro, whereas it expanded IL‐10−B cells over IL‐10+B cells during inflammatory responses, such as stimulation with autoantigen and LPS. Finally, the selection of IL‐10−B cells over IL‐10+B cells by BAFF was dependent on BAFF receptors (BAFFR, TACI, and BCMA) that were upregulated by inflammatory responses. This study suggests that BAFF selects IL‐10−B cells over IL‐10+ regulatory B cells via BAFF receptors in inflammatory responses. HighlightsBlockade of BAFF upregulates the percentage of IL‐10+ Bregs in lupus‐prone and EAE mice.BAFF selects IL‐10− over IL‐10+ B cells for expansion during inflammatory responses.Selection of IL‐10− over IL‐10+ B cells by BAFF were dependent on BAFF receptors.

Both Notch1 and its ligands in B cells promote antibody production

HighlightsBoth Notch1 and its ligands Dll1 and Jag1 express in B cells.Notch1 knock‐down in B cells reduces antibody production in LPS‐stimulated B cells.LPS‐activated splenocytes with Notch1‐knocked‐down B cells produce normal antibody.Notch1 knock‐down in B cells does not affect antibody production in EAE mice.Notch1 promotes Notch1‐knocked‐down B cells to produce antibody. &NA; Notch1 signaling regulates B and T lymphocyte development and also in vitro promotes antibody secretion upon B cell activation. However, it is still unclear about the role of Notch1 in antibody production upon in vitro and in vivo mixture lymphocytes activation. We first showed that Notch1 expressed in LPS‐activated CD19hi B cells and CD19cre mediated Notch1 knock‐down in LPS‐activated B cells. Furthermore, we demonstrated that Notch1 knock‐down in B cells reduced antibody production in LPS‐stimulated B cells but did not affect antibody production in LPS‐stimulated splenocytes and in experimental allergic encephalomyelitis (EAE) mice. Importantly, Notch1 ligands Dll1 and Jag1 expressed in B cells and pre‐coated Notch1 protein promotes Notch1‐knocked down B cells to produce antibody in LPS‐stimulated B cells suggesting that Notch1 in other cells may promote antibody production by binding its ligands Dll1 and Jag1 in B cells. Together, our results suggest that both Notch1 and its ligands in B cells play an important role in antibody production.