Unlike other types of T helper (Th) responses, whether the development of Th2 cells requires instruction from particular subset of dendritic cells (DCs) remains unclear. By using an in vivo depletion ...approach, we have shown that DCs expressing CD301b were required for the generation of Th2 cells after subcutaneous immunization with ovalbumin (OVA) along with papain or alum. CD301b+ DCs are distinct from epidermal or CD207+ dermal DCs (DDCs) and were responsible for transporting antigen injected subcutaneously with Th2-type adjuvants. Transient depletion of CD301b+ DCs resulted in less effective accumulation and decreased expression of CD69 by polyclonal CD4+ T cells in the lymph node. Moreover, despite intact cell division and interferon-γ production, CD301b+ DC depletion led to blunted interleukin-4 production by OVA-specific OT-II transgenic CD4+ T cells and significantly impaired Th2 cell development upon infection with Nippostrongylus brasiliensis. These results reveal CD301b+ DDCs as the key mediators of Th2 immunity.
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•CD301b is expressed by a major subset of DCs in dermis and submucosa•CD301b+ DCs facilitate CD4 T cell accumulation in the reactive lymph nodes•Transient depletion of CD301b+ DCs results in impaired Th2 cell responses in vivo
The tumor microenvironment includes a complex network of immune T-cell subpopulations. In this study, we systematically analyzed the balance between cytotoxic T cells and different subsets of helper ...T cells in human colorectal cancers and we correlated their impact on disease-free survival. A panel of immune related genes were analyzed in 125 frozen colorectal tumor specimens. Infiltrating cytotoxic T cells, Treg, Th1, and Th17 cells were also quantified in the center and the invasive margin of the tumors. By hierarchical clustering of a correlation matrix we identified functional clusters of genes associated with Th17 (RORC, IL17A), Th2 (IL4, IL5, IL13), Th1 (Tbet, IRF1, IL12Rb2, STAT4), and cytotoxicity (GNLY, GZMB, PRF1). Patients with high expression of the Th17 cluster had a poor prognosis, whereas patients with high expression of the Th1 cluster had prolonged disease-free survival. In contrast, none of the Th2 clusters were predictive of prognosis. Combined analysis of cytotoxic/Th1 and Th17 clusters improved the ability to discriminate relapse. In situ analysis of the density of IL17+ cells and CD8+ cells in tumor tissues confirmed the results. Our findings argue that functional Th1 and Th17 clusters yield opposite effects on patient survival in colorectal cancer, and they provide complementary information that may improve prognosis.
IL-9 is important for the growth and survival of mast cells. IL-9 is produced by T cells, natural killer T cells, mast cells, eosinophils, and innate lymphoid cells, although the cells required for ...mast cell accumulation during allergic inflammation remain undefined.
We sought to elucidate the role of TH9 cells in promoting mast cell accumulation in models of allergic lung inflammation.
Adoptive transfer of ovalbumin-specific TH2 and TH9 cells was used to assess the ability of each subset to mediate mast cell accumulation in tissues. Mast cell accumulation was assessed in wild-type mice and mice with PU.1-deficient T cells subjected to acute and chronic models of allergic inflammation.
Adoptive transfer experiments demonstrated that recipients of TH9 cells had significantly higher mast cell accumulation and expression of mast cell proteases compared with control or TH2 recipients. Mast cell accumulation was dependent on IL-9, but not IL-13, a cytokine required for many aspects of allergic inflammation. In models of acute and chronic allergic inflammation, decreased IL-9 levels in mice with PU.1-deficient T cells corresponded to diminished tissue mast cell numbers and expression of mast cell proteases. Mice with PU.1-deficient T cells have defects in IL-9 production from CD4+ T cells, but not natural killer T cells or innate lymphoid cells, suggesting a TH cell–dependent phenotype. Rag1−/− mice subjected to a chronic model of allergic inflammation displayed reduced mast cell infiltration comparable with accumulation in mice with PU.1-deficient T cells, emphasizing the importance of IL-9 produced by T cells in mast cell recruitment.
TH9 cells are a major source of IL-9 in models of allergic inflammation and play an important role in mast cell accumulation and activation.
On activation, T cells undergo distinct developmental pathways, attaining specialized properties and effector functions. T-helper (T(H)) cells are traditionally thought to differentiate into T(H)1 ...and T(H)2 cell subsets. T(H)1 cells are necessary to clear intracellular pathogens and T(H)2 cells are important for clearing extracellular organisms. Recently, a subset of interleukin (IL)-17-producing T (T(H)17) cells distinct from T(H)1 or T(H)2 cells has been described and shown to have a crucial role in the induction of autoimmune tissue injury. In contrast, CD4+CD25+Foxp3+ regulatory T (T(reg)) cells inhibit autoimmunity and protect against tissue injury. Transforming growth factor-beta (TGF-beta) is a critical differentiation factor for the generation of T(reg) cells. Here we show, using mice with a reporter introduced into the endogenous Foxp3 locus, that IL-6, an acute phase protein induced during inflammation, completely inhibits the generation of Foxp3+ T(reg) cells induced by TGF-beta. We also demonstrate that IL-23 is not the differentiation factor for the generation of T(H)17 cells. Instead, IL-6 and TGF-beta together induce the differentiation of pathogenic T(H)17 cells from naive T cells. Our data demonstrate a dichotomy in the generation of pathogenic (T(H)17) T cells that induce autoimmunity and regulatory (Foxp3+) T cells that inhibit autoimmune tissue injury.
Naive CD4+ T cell differentiation into distinct subsets of T helper (Th) cells is a pivotal process in the initiation of the adaptive immune response. Allergens predominantly stimulate Th2 cells, ...causing allergic inflammation. However, why allergens induce Th2 cell differentiation is not well understood. Here we show that group 2 innate lymphoid cells (ILC2s) are required to mount a robust Th2 cell response to the protease-allergen papain. Intranasal administration of papain stimulated ILC2s and Th2 cells, causing allergic lung inflammation and elevated immunoglobulin E titers. This process was severely impaired in ILC2-deficient mice. Whereas interleukin-4 (IL-4) was dispensable for papain-induced Th2 cell differentiation, ILC2-derived IL-13 was critical as it promoted migration of activated lung dendritic cells into the draining lymph node where they primed naive T cells to differentiate into Th2 cells. Papain-induced ILC2 activation and Th2 cell differentiation was IL-33-dependent, suggesting a common pathway in the initiation of Th2 cell responses to allergen.
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•ILC2-deficient mice have impaired Th2 cell responses to allergen•Allergen-induced Th2 cell differentiation is dependent on ILC2-derived IL-13•ILC2 activation by allergen requires IL-33 from epithelial cells•ILC2-derived IL-13 promotes DC migration to lymph node
Human milk oligosaccharides (HMOs) promote the development of the neonatal intestinal, immune, and nervous systems and has recently received considerable attention. Here we investigated how the ...maternal diet affects HMO biosynthesis and how any diet-induced HMO alterations influence the infant gut microbiome and immunity. Using capillary electrophoresis and MS-based analyses, we extracted and measured HMOs from breast milk samples and then correlated their levels with results from validated 24-h diet recall surveys and breast milk fatty acids. We found that fruit intake and unsaturated fatty acids in breast milk were positively correlated with an increased absolute abundance of numerous HMOs, including 16 sulfonated HMOs we identified here in humans for the first time. The diet-derived monosaccharide 5-N-glycolyl-neuraminic acid (Neu5Gc) was unambiguously detected in all samples. To gain insights into the potential impact of Neu5Gc on the infant microbiome, we used a constrained ordination approach and identified correlations between Neu5Gc levels and Bacteroides spp. in infant stool. However, Neu5Gc was not associated with marked changes in infant immune markers, in contrast with sulfonated HMOs, whose expression correlated with suppression of two major Th2 cytokines, IL-10 and IL-13. The findings of our work highlight the importance of maternal diet for HMO biosynthesis and provide as yet unexplored targets for future studies investigating interactions between HMOs and the intestinal microbiome and immunity in infants.
Review of the immune response to allergens and viral infections and how their distinct pathways regulate each other in the atopic host.
IFN‐α/β was first described as a potent inhibitor of viral ...replication, but it is now appreciated that IFN signaling plays a pleiotropic role in regulating peripheral T cell functions. Recently, IFN‐α/β was shown to block human Th2 development by suppressing the transcription factor GATA3. This effect is consistent with the role for IFN‐α/β in suppressing allergic inflammatory processes by blocking granulocyte activation and IL‐4‐mediated B cell isotype switching to IgE. With the consideration of recent studies demonstrating a defect in IFN‐α/β secretion in DCs and epithelial cells from individuals with severe atopic diseases, there is an apparent reciprocal negative regulatory loop in atopic individuals, whereby the lack of IFN‐α/β secretion by innate cells contributes to the development of allergic Th2 cells. Is it possible to overcome these events by treating with IFN‐α/β or by inducing its secretion in vivo? In support of this approach, case studies have documented the therapeutic potential of IFN‐α/β in treating steroid‐resistant allergic asthma and other atopic diseases. Additionally, individuals with asthma who are infected with HCV and respond to IFN therapy showed a reduction in symptoms and severity of asthma attacks. These findings support a model, whereby allergic and antiviral responses are able to cross‐regulate each other, as IgER cross‐linking of pDCs prevents IFN‐α/β production in response to viral infection. The clinical importance of upper‐respiratory viruses in the context of allergic asthma supports the need to understand how these pathways intersect and to identify potential therapeutic targets.
Given its critical role in T-cell signaling, interleukin-2–inducible kinase (ITK) is an appealing therapeutic target that can contribute to the pathogenesis of certain infectious, autoimmune, and ...neoplastic diseases. Ablation of ITK subverts Th2 immunity, thereby potentiating Th1-based immune responses. While small-molecule ITK inhibitors have been identified, none have demonstrated clinical utility. Ibrutinib is a confirmed irreversible inhibitor of Bruton tyrosine kinase (BTK) with outstanding clinical activity and tolerability in B-cell malignancies. Significant homology between BTK and ITK alongside in silico docking studies support ibrutinib as an immunomodulatory inhibitor of both ITK and BTK. Our comprehensive molecular and phenotypic analysis confirms ITK as an irreversible T-cell target of ibrutinib. Using ibrutinib clinical trial samples along with well-characterized neoplastic (chronic lymphocytic leukemia), parasitic infection (Leishmania major), and infectious disease (Listeria monocytogenes) models, we establish ibrutinib as a clinically relevant and physiologically potent ITK inhibitor with broad therapeutic utility. This trial was registered at www.clinicaltrials.gov as #NCT01105247 and #NCT01217749.
•Ibrutinib is the first clinically viable irreversible ITK inhibitor.•Ibrutinib inhibits the formation of Th2 but not Th1 immunity.
IL‐33, a new member of the IL‐1 family cytokine, is involved in Th2‐type responses in a wide range of diseases and signals through the ST2 receptor expressed on many immune cells. Since the effects ...of IL‐33 on DCs remain controversial, we investigated the ability of IL‐33 to modulate DC functions in vitro and in vivo. Here, we report that IL‐33 activates myeloid DCs to produce IL‐6, IL‐1b, TNF, CCL17 and to express high levels of CD40, CD80 OX40L and CCR7. Importantly, IL‐33‐activated DCs prime naive lymphocytes to produce the Th2 cytokines IL‐5 and IL‐13, but not IL‐4. In vivo, IL‐33 exposure induces DC recruitment and activation in the lung. Using an OVA‐induced allergic lung inflammation model, we demonstrate that the reduced airway inflammation in ST2‐deficient mice correlates with the failure in DC activation and migration to the draining LN. Finally, we show that adoptive transfer of IL‐33‐activated DCs exacerbates lung inflammation in a DC‐driven model of allergic airway inflammation. These data demonstrate for the first time that IL‐33 activates DCs during antigen presentation and thereby drives a Th2‐type response in allergic lung inflammation.
Although a fraction of human blood memory CD4+ T cells expresses chemokine (C-X-C motif) receptor 5 (CXCR5), their relationship to T follicular helper (Tfh) cells is not well established. Here we ...show that human blood CXCR5+CD4+ T cells share functional properties with Tfh cells and appear to represent their circulating memory compartment. Blood CXCR5+CD4+ T cells comprised three subsets: T helper 1 (Th1), Th2, and Th17 cells. Th2 and Th17 cells within CXCR5+, but not within CXCR5−, compartment efficiently induced naive B cells to produce immunoglobulins via interleukin-21 (IL-21). In contrast, Th1 cells from both CXCR5+ and CXCR5− compartments lacked the capacity to help B cells. Patients with juvenile dermatomyositis, a systemic autoimmune disease, displayed a profound skewing of blood CXCR5+ Th cell subsets toward Th2 and Th17 cells. Importantly, the skewing of subsets correlated with disease activity and frequency of blood plasmablasts. Collectively, our study suggests that an altered balance of Tfh cell subsets contributes to human autoimmunity.
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► Human blood CXCR5+CD4+ T cells have characteristics of circulating memory Tfh cells ► Human blood CXCR5+CD4+ T cells comprise three subsets: Th1, Th2, and Th17 cells ► Unlike CXCR5+ Th2 and Th17 cells, CXCR5+ Th1 cells do not help B cells ► CXCR5+ Th cell subsets are skewed toward Th2 and Th17 cells in juvenile dermatomyositis
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