Project description:Induction of alternative proinflammatory cytokines accounts for sustained psoriasiform skin inflammation in IL-17C+IL-6KO mice [RNA-Seq]
Project description:Macrophages are a major cellular component of all inflammatory situations, generating proinflammatory cytokines such as TNF-alpha, IL-1, and IL-6 that are central to the initiation and maintenance of inflammation. To determine whether the tumor suppressor ARF plays a role in inflammatory gene expression, we used an 84-gene RT2 PCR array to examine the expression of inflammation-associated genes in WT and ARF-deficient macrophages treated with the TLR4 ligand LPS.
Project description:IL-6 inhibition has been unsuccessful in treating psoriasis, despite high levels of tissue and serum IL-6 in patients. Additionally, de novo psoriasis onset has been reported following IL-6 blockade in rheumatoid arthritis patients. To explore mechanisms underlying these clinical observations, we backcrossed an established psoriasiform mouse model (IL-17C+ mice) with IL-6 deficient mice (IL-17C+KO) and examined the cutaneous phenotype. IL-17C+KO mice initially exhibited decreased skin inflammation, however this decrease was transient and reversed rapidly, concomitant with increases in skin Tnf, Il36α/β/γ, Il24, epigen and S100a8/a9 to levels higher than those found in IL-17C+ mice. Comparison of IL-17C+ and IL-17C+KO mouse skin transcriptomes with that of human psoriasis skin, revealed significant correlation among transcripts of psoriasis patient skin and IL-17C+KO mouse skin, and confirmed an exacerbation of the inflammatory signature in IL-17C+KO mice that aligns closely with human psoriasis. Transcriptional analyses of IL-17C+ and IL-17C+KO primary keratinocytes confirmed increased expression of proinflammatory molecules, suggesting that in the absence of IL-6, keratinocytes increase production of numerous additional proinflammatory cytokines. These preclinical findings may provide insight into why arthritis patients being treated with IL-6 inhibitors develop new onset psoriasis and why IL-6 blockade for the treatment of psoriasis has not been clinically effective.
Project description:IL-6 inhibition has been unsuccessful in treating psoriasis, despite high levels of tissue and serum IL-6 in patients. Additionally, de novo psoriasis onset has been reported following IL-6 blockade in rheumatoid arthritis patients. To explore mechanisms underlying these clinical observations, we backcrossed an established psoriasiform mouse model (IL-17C+ mice) with IL-6 deficient mice (IL-17C+KO) and examined the cutaneous phenotype. IL-17C+KO mice initially exhibited decreased skin inflammation, however this decrease was transient and reversed rapidly, concomitant with increases in skin Tnf, Il36α/β/γ, Il24, epigen and S100a8/a9 to levels higher than those found in IL-17C+ mice. Comparison of IL-17C+ and IL-17C+KO mouse skin transcriptomes with that of human psoriasis skin, revealed significant correlation among transcripts of psoriasis patient skin and IL-17C+KO mouse skin, and confirmed an exacerbation of the inflammatory signature in IL-17C+KO mice that aligns closely with human psoriasis. Transcriptional analyses of IL-17C+ and IL-17C+KO primary keratinocytes confirmed increased expression of proinflammatory molecules, suggesting that in the absence of IL-6, keratinocytes increase production of numerous additional proinflammatory cytokines. These preclinical findings may provide insight into why arthritis patients being treated with IL-6 inhibitors develop new onset psoriasis and why IL-6 blockade for the treatment of psoriasis has not been clinically effective.
Project description:GM-CSF paradoxically possesses ability to differentiate both classically activated macrophages (MØs) with dominant proinflammatory function (M1-like MØs) and alternative activated MØs with strong immunosuppressive function (M2-like MØs). The intrinsic regulatory mechanism responsible for functional polarization of MØs under GM-CSF signalling remains elusive. Here we revealed that cytokine-inducible SH2-containing protein (CIS), induced by GM-CSF, is a key determinant in controlling MØ polarization. Compared to WT MØs, Cish-/- MØs gained characteristics of alternative activated MØs (M2 MØs), showing high expression of prototypic M2 markers Arginase 1, Tgm2 and YM-1; strong suppression of T cell proliferation; and low production of IL-12 and other proinflammatory cytokines¬¬. Differing from canonical IL-4/STAT6/IRF4 signaling axis of M2 induction, development of M2 MØ characteristics in Cish-/- MØs was associated with intensified STAT5 activation and consequent IRF8 downregulation. Attenuation of GM-CSF signalling via JAK inhibition and IRF8 rescue corrected certain functional defects in Cish-/- MØs. As CIS inhibition in NK and T cells promotes anti-tumour immunity, we showed that CIS deficiency enhanced the development of intra-tumoural M2 MØs and reduced CTL induction within tumour microenvironment with elevated GM-CSF. Overall, we conclude that CIS acts as an intrinsic rheostat to control intense GM-CSF signalling in order to maintain proinflammatory functions of MØs. Targeting CIS as a checkpoint in cancer immunotherapy should consider its role in regulating myeloid cell function.
Project description:High levels of inflammation are often present in autoimmune diseases and can impact the functioning of the immune system. Specifically, how surrounding inflammation affects cytokine responses has not been extensively studied. We use IL-6 and IL-27, two cytokines playing opposite roles in inflammation, to ask how cytokines adapt to the inflammatory environment. We show that IL-27 induces a more sustained STAT1 phosphorylation than IL-6, with the two cytokines inducing comparable levels of STAT3 phosphorylation. Mathematical and statistical modelling of IL-6 and IL-27 signaling identify STAT1 (or STAT3) binding dynamics to GP130 (or IL-27R) as the main parameter contributing to sustained pSTAT1 by IL-27. Mutation of Tyr613 on IL-27R decreased IL-27-induced STAT1 phosphorylation by 80%, with limited effect on STAT3 phosphorylation. The strong receptor/STAT coupling by IL-27 led to the induction of a unique gene expression program by this cytokine, which required sustained STAT1 phosphorylation and IRF1 expression and was enriched in classical Interferon Stimulated Genes. Interestingly, the STAT/receptor coupling exhibited by IL-6/IL-27 was altered in Crohn’s disease and SLE patients. IL-6/IL-27 induced a more potent STAT1 activation in SLE patients than in healthy controls, which can be explained by the higher STAT1 expression in these patients. Partial inhibition of JAK activation by sub-saturating doses of Tofacitinib lowered the levels of STAT1 activation by IL-6, representing a new strategy to treat auto-immune disorders where cytokine responses are dysregulated.
Project description:The immune system can both promote and suppress cancer. Chronic inflammation and proinflammatory cytokines such as interleukin (IL)-1 and IL-6 are considered tumor-promoting. In contrast, the exact nature of protective antitumor immunity remains obscure. In this study, we have quantified locally secreted cytokines during primary immune responses against myeloma and B-cell lymphoma in mice. Strikingly, successful cancer immunosurveillance mediated by tumor-specific CD4+ T cells was consistently associated with elevated local levels of both proinflammatory (IL-1aplha, IL-1beta, and IL-6) and T helper 1 (Th1)-associated cytokines (interferon-alpha, IL-2, IL-12). Cancer eradication was achieved by a collaboration between tumor-specific Th1 cells and tumor-infiltrating, antigen-presenting macrophages. Th1 cells induced secretion of IL-1? and IL-6 by macrophages. Th1-derived interferon-? was shown to render macrophages directly cytotoxic to cancer cells, and to induce macrophages to secrete the angiostatic chemokines CXCL9/MIG and CXCL10/IP-10. Thus, inflammation, when driven by tumor-specific Th1 cells, may prevent rather than promote cancer. Tumoricidal macrophages were isolated from Idiotype-specific TCR-transgenic SCID mice injected with MOPC315-containing Matrigel. Control macrophages were obtained from TCR-transgenic SCID mice injected with Matrigel containing antigen-loss MOPC315.
Project description:Macrophages are a major cellular component of all inflammatory situations, generating proinflammatory cytokines such as TNF-alpha, IL-1, and IL-6 that are central to the initiation and maintenance of inflammation. To determine whether the tumor suppressor ARF plays a role in inflammatory gene expression, we used an 84-gene RT2 PCR array to examine the expression of inflammation-associated genes in WT and ARF-deficient macrophages treated with the TLR4 ligand LPS. Peritoneal macrophages from WT and ARF-deficient mice were obtained and treated with LPS (200ng/ml) for 4 hours. WT control (without stimulation n=4), WT LPS (n=4), ARF Control (n=4), ARF LPS (n=4)