Th17 Cell Polarization Research Articles

Myeloid-Derived Suppressor Cell-Derived Arginase-1 Oppositely Modulates IL-17A and IL-17F Through the ESR/STAT3 Pathway During Colitis in Mice

Myeloid-derived suppressor cells (MDSC) play a crucial role in regulating the intestinal immune response during colitis. We previously revealed an essential role of MDSC in promoting TH17 cell polarization, which was found to be arginase-1 (Arg-1)-dependent; however, the underlying mechanism remains obscure. Here we report that percentage of MDSC decreased in ArgmyeKO mice during DSS-induced colitis. IL-17A levels reduced but IL-17F levels increased significantly in the colorectum of ArgmyeKO mice, leading to severe tissue damage and high risk of mortality rate. Activation of estrogen receptor (ESR) increased pSTAT3 level in MDSC and consequently led to elevated percentage of MDSC and more Arg-1 and inducible nitric oxide synthase expression in MDSC. Increased level of IL-17A and reduced level of IL-17F alleviated colitis in mice consequently. Together, these findings demonstrate a protective role of MDSC-derived Arg-1 during colitis after activates ESR/STAT3 signaling in MDSC. High level of Arg-1 favors accumulation of IL-17A, but reduced IL-17F expression in the colorectum of mice and ultimately leading to relief of colitis, indicating a potential clinical impact of MDSC-derived Arg-1 for controlling inflammatory bowel disease.

Physcion-Matured Dendritic Cells Induce the Differentiation of Th1 Cells.

In addition to their use as colorants, anthraquinone derivatives have numerous medical applications, for example, as antibacterial and antiinflammatory agents. We confirmed that physcion (an anthraquinone derivative) induces TNF-alpha production by macrophages and increased the expressions of surface molecules (CD40, CD80, and CD86) and major histocompatibility complex (MHC) II. Based on these results, we hypothesized that physcion might induce the maturation of dendritic cells (DCs) to antigen-presenting cells (APCs), and decided to conduct in vitro experiments using bone-marrow-derived DCs (BMDCs). Physcion was not toxic to DCs and increased the expression of surface molecules (e.g., CD40, CD80, CD86, and MHC II) and the production of cytokines (e.g., IL-12p70, IL-1beta, IL-6, and TNF-alpha), but not of IL-10. To confirm that DCs matured by physcion induce T-cell-immune responses, naive CD4+ T cells were treated with physcion-treated DCs or their supernatants. Physcion induced the maturation of DCs, which promoted the polarization of Th1 cells. Our results show physcion-induced DC maturation via TLR4, and that mature DCs promote the differentiation of Th1 cells without affecting the differentiation of Th2 cells. These findings show that physcion has potential use as a treatment for inflammatory diseases associated with Th1/Th2 cell imbalance.

Mammalian Target of Rapamycin Signaling Enhances Ovalbumin-Induced Neutrophilic Airway Inflammation by Promoting Th17 Cell Polarization in Murine Noneosinophilic Asthma Model.

Background: T helper 17 (Th17) is regarded as key immune cell in the pathogenesis of noneosinophilic asthma (NEA) due to the recruitment of neutrophils into the airways. The mammalian target of rapamycin (mTOR) is an important signaling molecule that plays a critical role in immune regulation. This study focused on mTOR signaling pathway in the regulation of Th17-mediated neutrophilic airway inflammation. Methods: Ovalbumin (OVA) T cell receptor transgenic DO11.10 mice (DO11.10 mice) were used to establish NEA model, and few mice received specific mTORC1 inhibitor rapamycin (RAPA) before intranasal administration of OVA. The severity of airway inflammation was determined by differential cell counts in bronchoalveolar lavage (BAL) fluids and histopathologic lung analysis. The levels of various cytokines in BAL fluids and lung tissues were measured. To determine the role of mTORC1 signaling in Th17 differentiation, naive T cells from wild-type (WT) and TSC1 knockout (KO) mice were cultured in Th17 skewing condition with or without RAPA in vitro and the production of IL-17A was compared. Results: Treatment with RAPA markedly attenuated OVA-induced neutrophilic airway inflammation in DO11.10 mice. Also the production of IL-17A was inhibited without affecting the production of interferon-γ (IFN-γ) and IL-4 in lungs. Furthermore, RAPA suppressed differentiation of Th17 cells in vitro, whereas enhanced activity of mTORC1 promoted Th17 cell differentiation and increased the expression of Th17-related transcription factors RORγt and RORα. Conclusion: These results suggested that mTOR promoted Th17 cell polarization and enhanced OVA-induced neutrophilic airway inflammation in experimental NEA.

9 METABOLIC UTILIZATION OF PROPANEDIOL BY ADHERENT-INVASIVE E. COLI REGULATES INTESTINAL TISSUE IMMUNITY

Abstract While the molecular mechanisms by which the microbiome modulates mucosal immunity in Crohn’s disease (CD) are still largely unknown, recent data highlight the involvement of specific diet- and bacterial-derived metabolites in the regulation of intestinal immune cell activation and differentiation. We have recently shown that Adherent-Invasive E.coli (AIEC), which are enriched in CD patients, are sufficient to induce intestinal Th17 cells. Although AIEC lack pathogenic factors including type III secretion systems, many CD-derived isolates express virulence-associated metabolic enzymes including propanediol dehydratase (PduC), which enables AIEC to use fucose-derived propanediol as an alternate carbon source in the gut. We found that pduC is enriched in the microbiome and among E. coli genomes in CD patients compared to healthy controls. With fucosylated oligosaccharides on the surface of intestinal epithelial cells, we hypothesized that this propanediol utilization pathway provides AIEC a competitive advantage for epithelial cell adherence and intestinal immune cell activation. To evaluate the physiologic contribution of pduC to mucosal Th17 induction, we generated a pduC-deficient (ΔpduC) mutant of a CD-derived, AIEC isolate. Deletion of pduC resulted in reduced inflammatory Th17 cells and attenuated weight loss following T cell transfer colitis. Using genetic mouse models, we found that CX3CR1+ mononuclear phagocytes are required for this AIEC-mediated Th17 induction and IL-10 is required to restrain pduC-dependent dextran sodium sulfate (DSS)-induced colitis. Using a catalytically-inactive mutant, we determined that PduC metabolic activity was required for this immune phenotype. Cell-free supernatants from WT AIEC (but not the isogenic, pduC-deficient clone) promoted ex vivo Th17 cell polarization and metabolomics analysis (LC-MS) of these supernatants defined PduC-dependent metabolites capable of promoting Th17 polarization. These studies reveal a link between AIEC microbial metabolism and inflammatory Th17 cells with the potential to serve as a therapeutic target in the treatment of Crohn’s disease.

9 METABOLIC UTILIZATION OF PROPANEDIOL BY ADHERENT-INVASIVE E. COLI REGULATES INTESTINAL TISSUE IMMUNITY

While the molecular mechanisms by which the microbiome modulates mucosal immunity in Crohn’s disease (CD) are still largely unknown, recent data highlight the involvement of specific diet- and bacterial-derived metabolites in the regulation of intestinal immune cell activation and differentiation. We have recently shown that Adherent-Invasive E.coli (AIEC), which are enriched in CD patients, are sufficient to induce intestinal Th17 cells. Although AIEC lack pathogenic factors including type III secretion systems, many CD-derived isolates express virulence-associated metabolic enzymes including propanediol dehydratase (PduC), which enables AIEC to use fucose-derived propanediol as an alternate carbon source in the gut. We found that pduC is enriched in the microbiome and among E. coli genomes in CD patients compared to healthy controls. With fucosylated oligosaccharides on the surface of intestinal epithelial cells, we hypothesized that this propanediol utilization pathway provides AIEC a competitive advantage for epithelial cell adherence and intestinal immune cell activation. To evaluate the physiologic contribution of pduC to mucosal Th17 induction, we generated a pduC-deficient (ΔpduC) mutant of a CD-derived, AIEC isolate. Deletion of pduC resulted in reduced inflammatory Th17 cells and attenuated weight loss following T cell transfer colitis. Using genetic mouse models, we found that CX3CR1+ mononuclear phagocytes are required for this AIEC-mediated Th17 induction and IL-10 is required to restrain pduC-dependent dextran sodium sulfate (DSS)-induced colitis. Using a catalytically-inactive mutant, we determined that PduC metabolic activity was required for this immune phenotype. Cell-free supernatants from WT AIEC (but not the isogenic, pduC-deficient clone) promoted ex vivo Th17 cell polarization and metabolomics analysis (LC-MS) of these supernatants defined PduC-dependent metabolites capable of promoting Th17 polarization. These studies reveal a link between AIEC microbial metabolism and inflammatory Th17 cells with the potential to serve as a therapeutic target in the treatment of Crohn’s disease.

MiR-1165-3p Suppresses Th2 Differentiation via Targeting IL-13 and PPM1A in a Mouse Model of Allergic Airway Inflammation.

PurposeCD4+T cells are essential in the pathogenesis of allergic asthma. We have previously demonstrated that microRNA-1165-3p (miR-1165-3p) was significantly reduced in T-helper type (Th) 2 cells and that miR-1165-3p was a surrogate marker for atopic asthma. Little is known about the mechanisms of miR-1165-3p in the regulation of Th2-dominated allergic inflammation. We aimed to investigate the associations between Th2 differentiation and miR-1165b-3p in asthma as well as the possible mechanisms.MethodsCD4+ naïve T cells were differentiated into Th1 or Th2 cells in vitro. MiR-1165-3p was up-regulated or down-regulated using lentiviral systems during Th1/Th2 differentiation. In vivo, the lentiviral particles with the miR-1165-3p enhancer were administered by tail vein injection on the first day of a house dust mite -induced allergic airway inflammation model. Allergic inflammation and Th1/Th2 differentiation were routinely monitored. To investigate the potential targets of miR-1165-3p, biotin-microRNA pull-down products were sequenced, and the candidates were further verified with a dual-luciferase reporter assay. The roles of a target protein phosphatase, Mg2+/Mn2+-dependent 1A (PPM1A), in Th2 cell differentiation and allergic asthma were further explored. Plasma PPM1A was determined by ELISA in 18 subjects with asthma and 20 controls.ResultsThe lentivirus encoding miR-1165-3p suppressed Th2-cell differentiation in vitro. In contrast, miR-1165-3p silencing promoted Th2-cell development. In the HDM-induced model of allergic airway inflammation, miR-1165-3p up-regulation was accompanied by reduced airway hyper-responsiveness, serum immunoglobulin E, airway inflammation and Th2-cell polarization. IL-13 and PPM1A were the direct targets of miR-1165-3p. The expression of IL-13 or PPM1A was inversely correlated with that of miR-1165-3p. PPM1A regulated the signal transducer and activator of transcription and AKT signaling pathways during Th2 differentiation. Moreover, plasma PPM1A was significantly increased in asthmatic patients.ConclusionsMiR-1165-3p negatively may regulate Th2-cell differentiation by targeting IL-13 and PPM1A in allergic airway inflammation.

Mucosal-Associated Invariant T Cells in Tumors of Epithelial Origin.

Mucosal-associated invariant T (MAIT) cells are innate T lymphocytes that circulate in blood and also reside in mucosal tissues. Blood MAIT cells are typically highly Th1-polarized, while those in mucosal tissues include both Th1- and Th17-polarized subsets. MAIT cells mount cytokine and cytolytic responses as a result of T cell receptor (TCR)-mediated recognition of microbially derived metabolites of riboflavin (vitamin B2) presented by the MR1 antigen-presenting molecule. Additionally, MAIT cells can be activated by inflammatory cytokines produced by antigen-presenting cells (APCs) that have been exposed to pathogen-associated molecular patterns (PAMPs). Since the antigenic metabolites of riboflavin recognized by MAIT cells are produced by many microorganisms, including pathogens as well as non-pathogenic colonists, the inflammatory state of the tissue may be a key feature that determines the nature of MAIT cell responses. Under normal conditions where inflammatory cytokines are not produced, MAIT cell responses to microbial metabolites may simply serve to help maintain a healthy balance between epithelial cells and microbial colonists. In contrast, in situations where inflammatory cytokines are produced (e.g., pathogenic infection or damage to epithelial tissue), MAIT cell responses may be more potently pro-inflammatory. Since chronic inflammation and microbial drivers are associated with tumorigenesis and also trigger MAIT cell responses, the nexus of MAIT cells, local microbiomes, and epithelial cells may play an important role in epithelial carcinogenesis. This chapter reviews current information about MAIT cells and epithelial tumors, where the balance of evidence suggests that enrichment of Th17-polarized MAIT cells at tumor sites associates with poor patient prognosis. Studying the role of MAIT cells and their interactions with resident microbes offers a novel view of the biology of epithelial tumor progression and may ultimately lead to new approaches to target MAIT cells clinically.

Critical role of metabotropic glutamate receptor 4 in bone marrow-derived dendritic cells in the Th17 cell differentiation and the melanogenesis of B16 cells.

Vitiligo is an acquired pigmentary disorder resulting from selective destruction of melanocytes. Emerging studies have suggested that T helper cell 17 (Th17) is potentially implicated in vitiligo development and progression. It was recently discovered that metabotropic glutamate receptor 4 (mGluR4) can modulate Th17-mediated adaptive immunity. However, the influence of mGluR4 on melanogenesis of melanocytes has yet to be elucidated. In the present study, we primarily cultured mouse bone marrow-derived dendritic cells (BMDC) and then knocked down and over-expressed mGluR4 using transfection. Transduced BMDC were co-cultured with CD4+ T cells and the expression of Th17-related cytokines were measured. The morphology and melanogenesis of B16 cells were observed after being treated with co-culture medium of CD4+ T cells and transduced BMDC. We found that mGluR4 knockdown did not affect the co-stimulatory CD80 and CD86 upregulation after lipopolysaccharide stimulation but did increase the expression of Th17-related cytokines, and further down-regulated the expression of microphthalmia-associated transcription factor (MITF) and the downstream genes, decreased melanin production, and destroyed the morphology of B16 cells. Conversely, over-expression of mGluR4 reduced the expression of CD80 and CD86, suppressed the production of Th17-related cytokines, increased the expression of MITF, and did not destroy the morphology of B16 cells. Our study confirmed that mGluR4 modulated the Th17 cell polarization and resulted in the alteration of melanogenesis and morphology of B16 cells. Collectively, these findings suggest mGluR4 might be a potent target involved in the immune pathogenesis of vitiligo.

Субпопуляции Т-хелперов, ключевые цитокины и хемокины в патогенезе воспалительных заболеваний кишечника (часть 1)

This review summarizes the current scientific evidence on the role of different T helper (Th) cell subsets, key cytokines, and chemokines in inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease. According to modern concepts, not only type Th1, but also Th17, cytokines, and other cells of innate and adaptive immunity are involved in the immunopathogenesis of IBD. Most of the review is devoted to the current understanding of the role of polarized Th17 cells and subpopulations of follicular Th cells, the main function of which is to form a specific humoral immune response in IBD mediated by B cells. The role of the intestinal microbiota in the Th cell polarization, that is, their differentiation, accompanied by the acquisition of characteristics inherent in a particular subpopulation is discussed. The presented data are important for understanding the role of immune processes, including microbiome-associated ones, in the pathogenesis of IBD. Key words: inflammatory bowel disease, ulcerative colitis, Crohn’s disease, T helper cell subsets, cytokines, chemokines, gut microbiome

Essential functions of Runx/Cbfβ in gut conventional dendritic cells for priming Rorγt+ T cells.

Acquired immune responses are initiated by activation of CD4+ helper T (Th) cells via recognition of antigens presented by conventional dendritic cells (cDCs). DCs instruct Th-cell polarization program into specific effector Th subset, which will dictate the type of immune responses. Hence, it is important to unravel how differentiation and/or activation of DC are linked with Th-cell-intrinsic mechanism that directs differentiation toward a specific effector Th subset. Here, we show that loss of Runx/Cbfβ transcription factors complexes during DC development leads to loss of CD103+CD11b+ cDC2s and alters characteristics of CD103-CD11b+ cDCs in the intestine, which was accompanied with impaired differentiation of Rorγt+ Th17 cells and type 3 Rorγt+ regulatory T cells. We also show that a Runx-binding enhancer in the Rorc gene is essential for T cells to integrate cDC-derived signals to induce Rorγt expression. These findings reveal that Runx/Cbfβ complexes play crucial and complementary roles in cDCs and Th cells to shape converging type 3 immune responses.

α-mangostin attenuates pristane-induced lupus nephritis by regulating Th17 differentiation.

α-mangostin, a polyphenolic xanthone derivative of mangosteen, has been reported to possess multiple therapeutic properties, such as anti-cancer, anti-allergy and anti-inflammatory activity. However, its anti-inflammatory effects in autoimmune diseases such as lupus nephritis (LN) remain unclear. In this study, we want to investigate the therapeutic effect of α-mangostin in LN. First, we elucidated the retinoic acid receptor related orphan receptor gamma t (RORγt) inhibitory activity of α-mangostin in cell-based assay and T helper 17 (Th17) differentiation in vitro assay. Then, we established a pristane-induced LN mouse model and randomly divided these into a normal control group, model control group, α-mangostin group and prednisone acetate group. Finally, anti-double-stranded DNA (anti-dsDNA) level in serum was detected by enzyme-linked immunosorbent assay, interleukin (IL)-17A and interferon (IFN)-γ expression in spleen cells by flow cytometry; histomorphology examination of kidneys was performed by periodic acid-Schiff staining and immunofluorescence analysis with an anti-immunoglobulin G (anti-IgG) and anti-IgM antibodies. We found that α-mangostin inhibited RORγt transcription activity in a cell-based assay and also polarized Th17 cells in an in vitro induction experiment. Our results also showed that α-mangostin could significantly decrease serum anti-dsDNA antibody levels, IL-17A and IFN-γ expression and alleviate renal pathological damage in the α-mangostin-treated group mice than in the model group mice. Thus, α-mangostin demonstrated its potential as a candidate therapeutic drug for LN and other Th17-mediated autoimmune diseases by inhibiting the function of Th17.

AhR Activation by TCDD (2,3,7,8-Tetrachlorodibenzo-p-dioxin) Attenuates Pertussis Toxin-Induced Inflammatory Responses by Differential Regulation of Tregs and Th17 Cells Through Specific Targeting by microRNA.

The Aryl Hydrocarbon Receptor (AhR) is a transcription factor that, when activated by ligand-binding, has been shown to regulate the immune response. Pertussis Toxin (PTX) is a virulence factor found in Bordetella pertussis, a human respiratory pathogen that causes whooping cough. PTX promotes colonization and disease promotion by triggering a heightened inflammatory response. The role of AhR in the regulation of PTX-mediated inflammation has not previously been studied. In the current study, we investigate if AhR activation by 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a well characterized ligand, can attenuate PTX-mediated systemic inflammation. To that end, C57BL/6 mice were injected intraperitoneally (IP) with PTX twice and treated with TCDD or vehicle (VEH). The PTX+VEH group showed elevated levels of pro-inflammatory cytokines (IL-17A, IL-6, and IFNγ) in serum and increased proportions of CD4+ Th1 and Th17 cells in their spleens. In contrast, the PTX+TCDD group showed significantly lower levels of these inflammatory cytokines and decreased proportions of Th1 and Th17 cells, but increased proportions of Th2 and FoxP3+Tregs when compared to the PTX+VEH group. PTX+TCDD treated mice also showed elevated levels of IL-10, and TFG-b, potent anti-inflammatory cytokines. MicroRNAs (miRs) analysis of CD4+ T cells from the spleens of the PTX+TCDD treated mice revealed significant alterations in their expression and several of these miRs targeted cytokines and signaling molecules involved in inflammation. Specifically, the PTX+TCDD group had a significantly enhanced expression of miR-3082-5p that targeted IL-17, and a decreased expression of miR-1224-5p, which targeted FoxP3. Transfection studies with these miR mimics and inhibitors confirmed the specificity of the target genes. The current study suggests that AhR activation by TCDD suppresses PTX-induced inflammation through miR regulation that triggers reciprocal polarization of Tregs and Th17 cells and also suggests that AhR activation may serve as a treatment modality to suppress heightened inflammation induced during B. pertussis infection.

CD137L-DCs, Potent Immune-Stimulators-History, Characteristics, and Perspectives.

Dendritic cell (DC)-based immunotherapies are being explored for over 20 years and found to be very safe. Most often, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4)-induced monocyte-derived DCs (moDCs) are being used, which have demonstrated some life-prolonging benefit to patients of multiple tumors. However, the limited clinical response and efficacy call for the development of more potent DCs. CD137L-DC may meet this demand. CD137L-DCs are a novel type of monocyte-derived inflammatory DCs that are induced by CD137 ligand (CD137L) agonists. CD137L is expressed on the surface of antigen-presenting cells, including monocytes, and signaling of CD137L into monocytes induces their differentiation to CD137L-DCs. CD137L-DCs preferentially induce type 1 T helper (Th1) cell polarization and strong type 1 CD8+ T cell (Tc1) responses against tumor-associated viral antigens. The in vitro T cell-stimulatory capacity of CD137L-DCs is superior to that of conventional moDCs. The transcriptomic profile of CD137L-DC is highly similar to that of in vivo DCs at sites of inflammation. The strict activation dependence of CD137 expression and its restricted expression on activated T cells, NK cells, and vascular endothelial cells at inflammatory sites make CD137 an ideally suited signal for the induction of monocyte-derived inflammatory DCs in vivo. These findings and their potency encouraged a phase I clinical trial of CD137L-DCs against Epstein–Barr virus-associated nasopharyngeal carcinoma. In this review, we introduce and summarize the history, the characteristics, and the transcriptional profile of CD137L-DC, and discuss the potential development and applications of CD137L-DC.

REGγ controls Th17 cell differentiation and autoimmune inflammation by regulating dendritic cells.

Interleukin-17A (IL-17A)-producing helper T (Th17) cells are a subset of CD4+ T cells that play important pathological roles in autoimmune diseases. Although the intrinsic pathways of Th17 cell differentiation have been well described, how instructive signals derived from the innate immune system trigger the Th17 response and inflammation remains poorly understood. Here, we report that mice deficient in REGγ, a proteasome activator belonging to the 11S family, exhibit significantly deteriorated autoimmune neuroinflammation in an experimental autoimmune encephalomyelitis (EAE) model with augmented Th17 cell polarization in vivo. The results of the adoptive transfer of CD4+ T cells or dendritic cells (DCs) suggest that this phenotype is driven by DCs rather than T cells. Furthermore, REGγ deficiency promotes the expression of integrin αvβ8 on DCs, which activates the maturation of TGF-β1 to enhance Th17 cell development. Mechanistically, this process is mediated by the REGγ-proteasome-dependent degradation of IRF8, a transcription factor for αvβ8. Collectively, our findings delineate a previously unknown mechanism by which REGγ-mediated protein degradation in DCs controls the differentiation of Th17 cells and the onset of an experimental autoimmune disease.

First person – Hong-Hee Choi

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Hong-Hee Choi is first author on ‘PPE39 of the Mycobacterium tuberculosis strain Beijing/K induces Th1-cell polarization through dendritic cell maturation’, published in JCS. Hong-Hee is a research assistant in the lab of Sung Jae Shin at Yonsei University College of Medicine, South Korea, working on the development of effective controls for mycobacterial pathogens by regulating host signaling pathways.

CCL21/CCR7 signaling in macrophages promotes joint inflammation and Th17-mediated osteoclast formation in rheumatoid arthritis.

In rheumatoid arthritis (RA), synovial tissue abundantly expresses CCL21, a chemokine strongly associated with RA susceptibility. In this study, we aimed to characterize the functional significance of CCL21/CCR7 signaling in different phases of RA pathogenesis. We determined that CCR7 is a hallmark of RA M1 synovial fluid (SF) macrophages, and its expression in RA monocytes and in vitro differentiated macrophages is closely associated with disease activity score (DAS28). In early stages of RA, monocytes infiltrate the synovial tissue. However, blockade of SF CCL21 or CCR7 prevents RA SF-mediated monocyte migration. CCR7 expression in the newly migrated macrophages can be accentuated by LPS and IFNγ and suppressed by IL-4 treatment. We also uncovered that CCL21 stimulation increases the number of M1-polarized macrophages (CD14+CD86+), resulting in elevated transcription of IL-6 and IL-23. These CCL21-induced M1 cytokines differentiate naïve T cells to Th17 cells, without affecting Th1 cell polarization. In the erosive stages of disease, CCL21 potentiates RA osteoclastogenesis through M1-driven Th17 polarization. Disruption of this intricate crosstalk, by blocking IL-6, IL-23, or IL-17 function, impairs the osteoclastogenic capacity of CCL21. Consistent with our in vitro findings, we establish that arthritis mediated by CCL21 expands the joint inflammation to bone erosion by connecting the differentiation of M1 macrophages with Th17 cells. Disease progression is further exacerbated by CCL21-induced neovascularization. We conclude that CCL21 is an attractive novel target for RA therapy, as blockade of its function may abrogate erosive arthritis modulated by M1 macrophages and Th17 cell crosstalk.

Diversity of Th1/Th2 immunity in mice with acute lung injury induced by the H1N1 influenza virus and lipopolysaccharides.

The polarization of T helper (Th) cells plays an important role in the inflammatory response, pathogen removal, and tissue damage processes of infectious acute lung injury (ALI). However, Th cell polarization in viral- or bacterial-mediated ALI is not well defined. Herein, an influenza virus (A/FM/1/47, H1N1) and lipopolysaccharide (LPS) were chosen to induce ALI in mice, and the resultant diversity of Th-cell polarization was explored. BALB/c mice were challenged intranasally with the influenza virus or LPS. Edema of the lung, infiltration of inflammatory cells (macrophages, neutrophils, and lymphocytes), oxidative stress, and signature cytokines of Th1 and Th2 cells were detected at 2 days post virus or LPS challenge. The mice exhibited increased capillary permeability accompanied by lung edema and protein-rich alveolar exudation after virus or LPS challenge. Additionally, excessive infiltration of inflammatory cells, robust oxidative stress, and cytokine production were observed in both mouse groups. However, there was conspicuous disparity in the inflammatory cell infiltration and cytokines between the virus- and LPS-challenged mice, where the infiltration in virus-challenged mice was mainly of macrophages and accompanied by robust Th1 cytokine elevation, whereas the infiltration in LPS-challenged mice was primarily of neutrophils and accompanied by robust Th2 cytokine elevation. The Th cell polarization was skewed depending on whether ALI was induced by the influenza virus or LPS. The polarization in the virus-challenged mice was primarily toward a Th1 response, whereas that in the LPS-challenged mice was mainly toward Th2.

Artocarpus tonkinensis Protects Mice Against Collagen-Induced Arthritis and Decreases Th17 Cell Function.

Artocarpus tonkinensis (Moraceae) is a tree that grows in north Vietnam whose leaf decoction is used as a traditional remedy by the Hmong ethnic group to treat arthritis and backache. Our study evaluated the decoction’s efficacy and mechanism of action in DBA/1J mice with collagen-induced arthritis (CIA). Mice treated with the decoction (At) either from the first collagen immunization or after CIA development experienced significantly less joint edema and inflammatory infiltration, whereas CIA-induced cartilage damage could only be prevented by early At treatment. Autoimmune gene expression profiles showed that Th17 cell-associated chemokine CCL20 and cytokines IL-6, IL-17, and IL-22 were strongly downregulated by At. Reduced expression of IL-2, IL-17, IL-22, and FasL in lymph node cells from At-treated mice was further confirmed by real-time PCR. The decoction also inhibited polarization of Th17 cells from CD4+ splenic T cells according to levels of IL-17 and RORC, a Th17 cell-specific transcription factor. Chromatographic analysis identified At’s major component as maesopsin-β-D-glucoside, which could inhibit in vitro differentiation of Th17 cells. The decoction significantly alleviated the signs and symptoms of CIA and inhibited the development and function of Th17 cells, highlighting its potent anti-inflammatory activity.

Cannabinoid Receptor 1 Blockade Attenuates Obesity and Adipose Tissue Type 1 Inflammation Through miR-30e-5p Regulation of Delta-Like-4 in Macrophages and Consequently Downregulation of Th1 Cells.

Obesity is characterized by chronic low-grade inflammation that contributes to development of cardiometabolic disorders. Cannabinoid receptor 1 (CB1) antagonists attenuate diet-induced obesity (DIO) and related inflammation, although the precise anti-inflammatory mechanisms involved have not been fully explored. In the current study we used a mouse model of DIO intervention to determine the microRNA (miRNA, miR)-mediated anti-obesity and anti-inflammatory effects of the CB1 antagonist, AM251. DIO mice that were fed high-fat diet (HFD) for 12 weeks were treated with AM251 (10 mg/kg) for an additional 4 weeks. HFD + AM251 mice experienced rapid and prolonged weight loss and reduced inflammatory M1 adipose tissue macrophage (ATM) infiltration. To investigate miRNA-mediated regulation of ATMs, F4/80+ cells from stromal vascular fractions (SVF) of epididymal fat were subjected to miR microarray analysis. Several miRs were differentially expressed in AM251-treated mice that were independent of calorie restriction. Prominently, miR-30e-5p was upregulated in ATMs from HFD + AM251 mice while the miR-30e-5p target, DLL4, was downregulated. Consistent with a decrease in DLL4-Notch signaling, fat storage and pro-inflammatory cytokine/chemokine expression was reduced following AM251 treatment. Furthermore, we found that AM251-treated macrophages can suppress DLL4-mediated Th1 polarization in CD4+ T cells. Together these data demonstrate that blocking CB1 receptors leads to upregulation of miR-30e-5p and down regulation of DLL4 in ATMs, which in turn suppress DLL4-Notch signaling-induced polarization of inflammatory Th1 cells and adipocyte energy storage. This combined effect of ATMs and T cells leads to an anti-inflammatory state and attenuation of DIO. These data support therapeutic potential of miR-30 in the treatment of cardiometabolic disorders.

The Cd8 locus Controls the Functional Conversion of CD4 Th cells to CD4 CTL in the Intestine

Abstract CD4 T cells adapt to their surroundings by differentiating into various T helper (Th) subsets. At steady state, regulatory CD4 T cells (Treg) and interleukin (IL)-17 producing CD4 T cells (Th17 cells) are present in the intestine and localize mainly to the lamina propria, whereas CD4 cytotoxic T lymphocytes (CTL) reside in the epithelium. A hallmark of CD4 CTL is the reactivation of the Cd8 locus and the re-expression of CD8a controlled by the Cd8 enhancer I (E8I). We showed before that CD4 Th cells can reprogram to CTL. Here, we elucidated a mechanism that drives the CTL reprogramming of CD4 Th cells. We identified a long noncoding RNA transcribed from the Cd8 locus, as the critical regulator of the reciprocal expression of T-BET and RUNX combined with the suppression of Foxp3 and Rorc in CD4 CTL precursors. We further found that the E8I region functions as is central coordinator of the RUNX3-controlled cytotoxic gene expression program marked by the re-expression of CD8a. Adoptive transfer of naïve E8I deletion mutant CD4 T cells to Rag1−/− recipient mice led to accelerated weight loss, and severe small and large intestine inflammation with excessive accumulation of pathogenic IL-17A and IL-17A/IFNg double producing CD4 T cells. Altogether, these findings indicate that the Cd8 locus controls the functional polarization of CD4 Th cells and furthermore, that the conversion to CTL not only enhances the direct protective capacity but also regulate the immune response and prevents excessive inflammation and immune pathology at the mucosal border of the intestine.