Bcl-3 is an atypical NF-κB family member that regulates NF-κB-dependent gene expression in effector T cells, but a cell-intrinsic function in regulatory T (Treg) cells and colitis is not clear. Here ...we show that Bcl-3 expression levels in colonic T cells correlate with disease manifestation in patients with inflammatory bowel disease. Mice with T-cell-specific overexpression of Bcl-3 develop severe colitis that can be attributed to defective Treg cell development and function, leading to the infiltration of immune cells such as pro-inflammatory γδT cells, but not αβ T cells. In Treg cells, Bcl-3 associates directly with NF-κB p50 to inhibit DNA binding of p50/p50 and p50/p65 NF-κB dimers, thereby regulating NF-κB-mediated gene expression. This study thus reveals intrinsic functions of Bcl-3 in Treg cells, identifies Bcl-3 as a potential prognostic marker for colitis and illustrates the mechanism by which Bcl-3 regulates NF-κB activity in Tregs to prevent colitis.
Laquinimod is an orally administered compound that is under investigation in relapsing-remitting multiple sclerosis. To understand the mechanism by which laquinimod exerts its clinical effects, we ...have performed human and murine studies assessing its immunomodulatory properties. In experimental autoimmune encephalomyelitis, the therapeutic administration of laquinimod beginning during the recovery of SJL mice, prevented further relapses as expected and strongly reduced infiltration of CD4+ and CD8+ T cells in the central nervous system. We hypothesized that this beneficial effect was mediated by dendritic cells, since we and others found a modulation of different dendritic cell subsets under treatment. According to the findings on antigen-presenting cells in the murine system, we found a reduced capacity of human monocyte-derived dendritic cells treated with therapeutic concentrations of laquinimod, upon maturation with lipopolysaccharide, to induce CD4+ T cell proliferation and secretion of pro-inflammatory cytokines. Furthermore, laquinimod treatment of mature dendritic cells resulted in a decreased chemokine production by both murine and human dendritic cells, associated with a decreased monocyte chemo-attraction. In laquinimod-treated patients with multiple sclerosis we consistently found reduced chemokine and cytokine secretion by conventional CD1c+ dendritic cells upon lipopolysaccharide stimulation. Similarly to the animal model of relapsing-remitting multiple sclerosis, dendritic cell subsets were altered in patients upon laquinimod treatment, as the number of conventional CD1c+ and plasmacytoid CD303+ dendritic cells were decreased within peripheral blood mononuclear cells. Moreover, laquinimod treatment in patients with multiple sclerosis and mice modified the maturation of dendritic cells demonstrated by an upregulation of CD86 expression in vivo. Our data suggest that inhibition of the NF-κB pathway is responsible for the changes observed in dendritic cell maturation and functions. These findings indicate that laquinimod exhibits its disease-modulating activity in multiple sclerosis by downregulating immunogenicity of dendritic cell responses. We suggest that monitoring dendritic cell properties in multiple sclerosis should be implemented in future therapeutic trials.
Abstract
IL-6 is a pleiotropic cytokine that regulates development and function of variety immune cells. Here we used a novel mouse strain in which IL-6 can be overexpressed in a Cre-dependent manner ...and show that mice with CD11c-Cre mediated IL-6 overexpression succumb from systemic inflammation. High levels of IL-6 perturbed B and T cell development in primary lymphoid organs, bone marrow and thymus. Interestingly, IL-6-triggered inflammation promoted expansion of both Th17 and Treg cells, two cell types known for their reciprocal developmental requirements. However, the most dramatic increase was noted for myeloid cells, mostly neutrophils, which invaded spleen, thymus and blood of mice with IL-6 overexpression. Observed systemic inflammation ultimately led to mice mortality within 11 weeks of age. Mechanistically, IL-6 mediates its biological functions strictly through binding to IL-6R alpha chain followed by recruitment of the signal transducer gp130. Previously, an alternative pathway was suggested in which IL-6 can utilize CD5 to signal via gp130. However, when IL-6R was deleted in mice with IL-6 overexpression these mice were completely protected from IL-6- triggered pathology and fully phenocopied IL-6R deficient mice. In fact, IL-6R deficiency prevented downstream activation of STAT3 in response to IL-6. Together, our data suggest that IL-6R is the only biological relevant receptor for IL-6 in mice.
The function of NF-kappaB family members is controlled by multiple mechanisms including the transcriptional regulator Bcl-3, an atypical member of the IkappaB family. By using a murine model of ...conditional Bcl-3 overexpression specifically in T cells, we observed impairment in the development of Th2, Th1, and Th17 cells. High expression of Bcl-3 promoted CD4+ T-cell survival, but at the same time suppressed proliferation in response to TCR stimulation, resulting in reduced CD4+ T-cell expansion. As a consequence, T-cell-specific overexpression of Bcl-3 led to reduced inflammation in the small intestine of mice applied with anti-CD3 in a model of gut inflammation. Moreover, impaired Th17-cell development resulted in the resistance of Bcl-3 overexpressing mice to EAE, a mouse model of multiple sclerosis. Thus, we concluded that fine-tuning expression of Bcl-3 is needed for proper CD4+ T-cell development and is required to sustain Th17-cell mediated pathology.
IL-6 binds to the IL-6R α-chain (IL-6Rα) and signals via the signal transducer gp130. Recently, IL-6 was found to also bind to the cell surface glycoprotein CD5, which would then engage gp130 in the ...absence of IL-6Rα. However, the biological relevance of this alternative pathway is under debate. In this study, we developed a mouse model, in which murine IL-6 is overexpressed in a CD11c-Cre-dependent manner. Transgenic mice developed a lethal immune dysregulation syndrome with increased numbers of Ly-6G
neutrophils and Ly-6C
monocytes/macrophages. IL-6 overexpression promoted activation of CD4
T cells while suppressing CD5
B-1a cell development. However, additional ablation of IL-6Rα protected IL-6-overexpressing mice from IL-6-triggered inflammation and fully phenocopied IL-6Rα-deficient mice without IL-6 overexpression. Mechanistically, IL-6Rα deficiency completely prevented downstream activation of STAT3 in response to IL-6. Altogether, our data clarify that IL-6Rα is the only biologically relevant receptor for IL-6 in mice.
The function of NF‐κB family members is controlled by multiple mechanisms including the transcriptional regulator Bcl‐3, an atypical member of the IκB family. By using a murine model of conditional ...Bcl‐3 overexpression specifically in T cells, we observed impairment in the development of Th2, Th1, and Th17 cells. High expression of Bcl‐3 promoted CD4+ T‐cell survival, but at the same time suppressed proliferation in response to TCR stimulation, resulting in reduced CD4+ T‐cell expansion. As a consequence, T‐cell‐specific overexpression of Bcl‐3 led to reduced inflammation in the small intestine of mice applied with anti‐CD3 in a model of gut inflammation. Moreover, impaired Th17‐cell development resulted in the resistance of Bcl‐3 overexpressing mice to EAE, a mouse model of multiple sclerosis. Thus, we concluded that fine‐tuning expression of Bcl‐3 is needed for proper CD4+ T‐cell development and is required to sustain Th17‐cell mediated pathology.
Expression of Bcl‐3, an atypical member of NF‐κB inhibitors, is fine‐tuned in CD4+ T cells during development. Constitutive expression of Bcl‐3 prevents Th17‐cell development and results in resistance of mice to the induction of experimental autoimmune encephalomyelitis (EAE).
Abstract Aims The cytokine interleukin-6 (IL-6) plays a central role in the inflammation cascade as well as in cardiovascular disease progression. Since myeloid cells are a primary source of IL-6 ...formation, we aimed to generate a mouse model to study the role of myeloid cell-derived IL-6 in vascular disease. Method and Results IL-6 overexpressing (IL-6OE) mice were generated and crossed with LysM-Cre mice, to generate mice (LysM-IL-6OE mice) overexpressing the cytokine in myeloid cells. Eight to 12 week old LysM-IL-6OE mice spontaneously developed inflammatory colitis, significantly impaired endothelium dependent aortic relaxation, increased aortic reactive oxygen species (ROS) formation and vascular dysfunction in resistance vessels. The latter phenotype was associated with decreased survival. Vascular dysfunction was accompanied by a significant accumulation of neutrophils, monocytes and macrophages in the aorta, increased myeloid cell reactivity (elevated ROS production), and vascular fibrosis associated with phenotypic changes of vascular smooth muscle cells. In addition to elevated Mcp1 and Cxcl1 mRNA levels, aortae from LysM-IL-6OE mice expressed higher levels of iNOS and endothelin-1, thus partially accounting for vascular dysfunction whereas systemic blood pressure alterations were not observed. Bone marrow transplantation experiments revealed that vascular dysfunction and ROS formation were driven by bone marrow cell-derived IL-6 in a dose-dependent manner. Conclusion Mice with conditional overexpression of IL-6 in myeloid cells show systemic and vascular inflammation as well as endothelial dysfunction. Decrease of circulating IL-6 levels by replacing IL-6 producing myeloid cells in the bone marrow improved vascular dysfunction in this model, underpinning the relevant role of IL-6 in vascular disease.
Abstract
Bcl-3 is a proto-oncogene belonging to the IκB family. It has been reported to exert both inhibitory as well as activating function, depending on the cellular context. It has previously been ...shown that its overexpression slows T cell activation very early in T cell responses to antigen. We could show by endoscopy and immunohistochemistry that mice overexpressing Bcl-3 in T cells (CD4-Cre ROSA-CAGs-STOP-Bcl-3-EGFP, henceforth termed CD4-Cre Bcl-3) develop spontaneous colitis and could observe a massive infiltration of immune cells into the colonic mucosa. CD4+ T cells overexpressing Bcl-3 show enhanced survival capacity in in vitro culture, but have an impaired proliferative capacity when stimulated in vitro or when adoptively transferred into lymphopenic Rag1-/- recipients. When compared to control littermates CD4-Cre Bcl-3 mice have less peripheral memory/effector T cells and less Th1 cells, whereas Th17 numbers remain unaltered. Naïve T cells overexpressing Bcl-3 show defects in in vitro differentiation to the Th1 or Th17 fate. Ex vivo isolated Bcl-3-overexpressing regulatory T cells display diminished suppressive capacity in vitro and in vivo. Interpretation of the observed phenotype will require the elucidation of the molecular role of Bcl-3 in T cell activation and proliferation.
Deubiquitination of NF-κB members by CYLD is crucial in controlling the magnitude and nature of cell activation. The role of the naturally occurring CYLD splice variant in dendritic cell (DC) ...function was analyzed using CYLDex7/8 mice, which lack the full-length CYLD (flCYLD) transcript and overexpress the short splice variant (sCYLD). Bone marrow–derived DCs from CYLDex7/8 mice display a hyperactive phenotype in vitro and in vivo and have a defect in establishing tolerance with the use of DEC-205–mediated antigen targeting to resting DCs. The combination of sCYLD overexpression and lack of flCYLD in CYLDex7/8 DCs leads to enhanced NF-κB activity accompanied by an increased nuclear translocation of the IκB molecule Bcl-3, along with nuclear p50 and p65. This suggests that, in contrast to flCYLD, sCYLD is a positive regulator of NF-κB activity, and its overexpression induces a hyperactive phenotype in DCs.
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![[YIA] Myeloid cell derived ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0891-5849/small "[YIA] Myeloid cell derived Interleukin-6 causes vascular dysfunction, inflammation and endothelin-1 expression in mice")
