Epstein-Barr virus-induced gene 3 (EBI3) and the p35 subunit of IL-12 have been reported to form a heterodimeric hematopoietin in human and mouse. We have constructed a heterodimeric protein covalently linking EBI3 and p35, to form a novel cytokine which we now call IL-35. The

Interleukin (IL)- [26] and is a proinflammatory cytokine in CIA [14,27]. Recent studies have also shown that the IL-33/ST2 pathway plays a significant role in the amplification of M2 polarization and chemokine production, which contribute to innate and antigen-induced airway inflammation [28] and protect against obesity-related metabolic events [29].Interestingly, the highest levels of IL-33 expression in naïve mice are found in the brain and spinal cord [15], indicating that IL-33 may have CNS-specific functions in addition to its role in immune modulation. Astrocytes express both and the expression of IL-33 in the CNS was increased in response to inflammatory stimuli [31]. Recently, it was also reported that IL-33 levels were elevated in the periphery and CNS of MS patients, implicating IL-33 in the pathogenesis of MS [32]. However, the precise role of IL-33 and its receptor in CNS under healthy and inflammatory conditions remain unclear.In the present study, we show that ST2 1C). Quantitative PCR analysis confirmed the upregulation of ST2 expression in Fig. 1B as it clearly shows the enhanced expression of ST2 mRNA in the CNS of mice with EAE compared with that of the naïve mice (Fig. 1D). ST2 −/− mice developed exacerbated EAETo identify an endogenous role of IL-33 in EAE, we next investigated the development of EAE in ST2 −/− mice. EAE was induced in C57BL/6 WT and ST2 −/− mice, Fig. 2A shows that the ST2 −/− mice developed more severe EAE than that in the WT mice. In agreement with many previous reports, BALB/c mice are resistant to the induction of EAE. However ST2 −/− BALB/c mice developed a mild but clearly detectable EAE while the WT BALB/c controls did not (Fig. 2B), the observation was further confirmed by histological analysis of the CNS tissues at day 19 after immunization ( Fig. 2C). Minimal leukocyte infiltration was found in the CNS of WT BALB/c mice whereas significant leukocyte infiltration was found in the submeningeal infiltration in the CNS tissues of ST2 −/− BALB/c mice ( Fig. 2C). IL-33 treatment attenuates EAE developmentWe next investigated the effect of exogenous IL-33 in the development of EAE. C57BL/6 mice were immunized as described in was injected intraperitoneally to each mouse daily from day 12 to day 20 after immunization. Both groups of mice developed similar degree of EAE from day 10 to day 15. However, from day 15, mice treated with IL-33 recovered significantly faster than the control mice treated with PBS ( Fig. 3A). In induced experimental autoimmune diseases, disease severity could vary between experiments even with the same protocol. Analysis using multiple comparisons suggests that the effect of IL-33 treatment on the outcome of EAE mice could be time revealed marked reduction of infiltrating cells in the spinal cord tissues of IL-33-treated mice (Fig. 3B). Importantly, IL-33 had no effect on the disease development in ST2 −/− C57BL/6 mice ( Fig. 3C) demonstrating the specificity of the IL-33 effect. IL-33 alters the cytokine production of EAE miceTo investigate the i...

Patients who survive sepsis can develop long-term immune dysfunction, with expansion of the regulatory T (Treg) cell population. However, how Treg cells proliferate in these patients is not clear. Here we show that IL-33 has a major function in the induction of this immunosuppression. Mice deficient in ST2 (IL-33R) develop attenuated immunosuppression in cases that survive sepsis, whereas treatment of naive wild-type mice with IL-33 induces immunosuppression. IL-33, released during tissue injury in sepsis, activates type 2 innate lymphoid cells, which promote polarization of M2 macrophages, thereby enhancing expansion of the Treg cell population via IL-10. Moreover, sepsis-surviving patients have more Treg cells, IL-33 and IL-10 in their peripheral blood. Our study suggests that targeting IL-33 may be an effective treatment for sepsis-induced immunosuppression.

These results demonstrate that IL27 may be a potential therapeutic agent against RA at the onset of the disease.

We have previously reported that mice lacking inducible nitric oxide synthase (NOS2) developed enhanced Th1 cell responses. We now investigated the mechanism by which NO modulates Th1 cells differentiation. Peritoneal macrophages from NOS2-deficient mice infected with Leishmania major in vivo or stimulated with IFN-gamma or lipopolysaccharide (LPS) in vitro produced significantly higher levels of IL-12 than those from heterozygous or wild-type mice. A macrophage cell line, J774, produced significant amounts of IL-12 following activation with LPS, or LPS plus IFN-gamma. This could be markedly enhanced by the NOS inhibitor L-NG monomethyl arginine (L-NMMA), but profoundly inhibited by the NO-generating compound S-nitroso-N-acetyl-penicillamine (SNAP). The effect of NO in this system is selective, since SNAP enhanced and L-NMMA decreased TNF-alpha synthesis by LPS-activated J774 cells. The differential effect of NO on IL-12 and TNF-alpha is at the transcriptional level and is activation dependent. Since IL-12 is a major inducer of Th1 cells which produce IFN-gamma that can activate macrophages to produce IL-12, our data demonstrate that NO can be an inhibitor of this feedback loop, preventing the excessive amplification of Th1 cells which are implicated in a range of immunopathologies.

No abstract

The principal aim of the immune system is to establish a balance between defense against pathogens and avoidance of autoimmune disease. This balance is achieved partly through regulatory T cells (Tregs) ϩ CD25 ϩ Tregs are arguably the best characterized, principally because it is relatively easy to obtain a large number of cells. The main characteristic of Tregs is the expression of the intracellular X-linked forkhead/ winged helix transcription factor, Foxp3 (4-6). Here we report a previously unrecognized subset of Foxp3 Ϫ CD4 ϩ CD25 ϩ Tregs (NO-Tregs) derived from CD4 ϩ CD25 Ϫ T cells and induced by nitric oxide (NO)..NO is a key mediator of a variety of biological functions, such as vascular relaxation, platelet aggregation, neurotransmission, tumoricidal and microbicidal activities, and immunosuppression (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). NO also is associated with some of the most important immunopathologies, including rheumatoid arthritis, diabetes, systemic lupus erythematosus, and septic shock (12-14). However, the mechanisms by which NO mediates this spectrum of diseases remain obscure.NO is derived from the guanidino nitrogen atoms (15) and molecular oxygen (16, 17) in a reaction catalyzed by the enzyme NO synthase (NOS). There are three forms of NOS. The endothelial (eNOS or NOS1) and neuronal (nNOS or NOS3) forms produce the amount of NO required for physiological functions. The cytokine-inducible form (iNOS or NOS2) is activated by a number of immunological stimuli, such as IFN␥, TNF␣, and LPS, and catalyzes a high output of NO, which can be cytotoxic. Direct evidence for the critical biological functions of NOS has been provided by strains of mice with disrupted NOS genes (21-23).We previously reported that NO selectively enhanced type 1 helper T (Th1) cell differentiation and expansion. This process was mediated by enhanced IL-12 receptor ␤2 expression through a cGMP-dependent pathway (24). Th1 cells are key players in the host immune defense against pathogens, as well as causing a range of autoimmune inflammatory conditions, some of which are NOdependent. We wondered how this NO-Th1 self-amplification cycle might be regulated. A potential candidate would be Tregs. We now report that NO, together with anti-CD3 [(␣CD3) triggering T cell antigen receptor (TcR)] activation, induced the proliferation and sustained survival of CD4 ϩ CD25 Ϫ T cells, which became CD4 ϩ CD25 ϩ but remained Foxp3 Ϫ . The induction process depended on the hitherto unrecognized p53-IL-2-OX40-survivin signaling pathway. This previously unrecognized population of Tregs suppressed the proliferation and function of freshly purified CD4 ϩ CD25Ϫ effector cells in vitro and colitis-and collagen-induced arthritis in the mouse in an IL-10-dependent manner. Therefore, this report links the functions of NO, p53, and Tregs, three key areas of biomedicine.

Cerebral malaria (CM) is a complex parasitic disease caused by Plasmodium sp. Failure to establish an appropriate balance between pro- and anti-inflammatory immune responses is believed to contribute to the development of cerebral pathology. Using the blood-stage PbA (Plasmodium berghei ANKA) model of infection, we show here that administration of the pro-Th2 cytokine, IL-33, prevents the development of experimental cerebral malaria (ECM) in C57BL/6 mice and reduces the production of inflammatory mediators IFN-γ, IL-12 and TNF-α. IL-33 drives the expansion of type-2 innate lymphoid cells (ILC2) that produce Type-2 cytokines (IL-4, IL-5 and IL-13), leading to the polarization of the anti-inflammatory M2 macrophages, which in turn expand Foxp3 regulatory T cells (Tregs). PbA-infected mice adoptively transferred with ILC2 have elevated frequency of M2 and Tregs and are protected from ECM. Importantly, IL-33-treated mice deleted of Tregs (DEREG mice) are no longer able to resist ECM. Our data therefore provide evidence that IL-33 can prevent the development of ECM by orchestrating a protective immune response via ILC2, M2 macrophages and Tregs.