Mast cells and basophils are potent effector cells of the innate immune system, and they have both beneficial and detrimental functions for the host. They are mainly implicated in pro-inflammatory ...responses to allergens but can also contribute to protection against pathogens. Although both cell types were identified more than 130 years ago by Paul Ehrlich, their in vivo functions remain poorly understood. The precursor cell populations that give rise to mast cells and basophils have recently been characterized and isolated. Furthermore, new genetically modified mouse strains have been developed, which enable more specific targeting of mast cells and basophils. Such advances offer new opportunities to uncover the true in vivo activities of these cells and to revisit their previously proposed effector functions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
2.
Basophil modulation by cytokine instruction Voehringer, David
European journal of immunology,
October 2012, 2012-Oct, 2012-10-00, 20121001, Letnik:
42, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Basophils have recently been recognized as critical effector cells in allergic reactions and protective immunity against helminths. Precise characterization of basophil biology could help to develop ...specific therapies that interfere with differentiation, tissue recruitment, or induction of effector functions and thereby ameliorate allergic disorders. The development, homeostasis, and effector functions of basophils are tightly regulated by extrinsic signals and in particular by cytokines. IL‐3, GM‐CSF, and thymic stromal lymphopoietin activate the STAT5 pathway that promotes proliferation, activation, and cytokine secretion but also induces a negative feedback loop via Pim‐1 and SOCS proteins. Basophils further express receptors for IL‐18 and IL‐33, which are associated with the signaling adaptor MyD88 and activate the NF‐κB and MAP kinase pathways. This review focuses on positive and negative regulation of basophils by these cytokines.
Infection of mice with the gastrointestinal helminth Nippostrongylus brasiliensis elicits profound local proliferation and accumulation of type 2 innate lymphoid cells (ILC2s) in the lung. The ...regulation of ILC2 proliferation and accumulation in the lung is poorly understood. Using T cell‐specific IL‐4/IL‐13‐deficient mice, we demonstrate that IL‐4/IL‐13 secretion from Th2 cells promotes proliferation and expansion of the ILC2 population in the lung of N. brasiliensis‐infected mice. Competitive mixed BM chimeras containing normal and STAT6‐deficient ILC2s further indicated that ILC2s have to respond directly to IL‐4/IL‐13 for this effect while STAT6 is not required for IL‐13 production in ILC2s. In addition, expression of a constitutively active form of STAT6 in ILC2s was sufficient to promote their proliferation in uninfected mice. The expression of MHC class II in ILC2s appeared to be enhanced by STAT6 signaling supporting the concept that Th2 cells and ILC2s can communicate in an antigen‐dependent manner resulting in a Th2‐regulated accumulation of ILC2s in the lung during an acute type 2 immune response. Based on our observations, targeting the STAT6 pathway in ILC2s could help to develop new treatments to dampen ILC2 proliferation in the lung and thereby ameliorate ILC2‐mediated allergic inflammation.
This study demonstrates that Th2 cell‐derived IL‐4/IL‐13 enhances the proliferation and accumulation of ILC2s in the lung of helminth‐infected mice. This effect is mediated by ILC2‐intrinsic expression of STAT6 and correlates with upregulation of MHC class II expression suggesting an antigen‐dependent positive feedback regulation of ILC2 accumulation in the lung.
Basophils are mainly known as pro-inflammatory effector cells associated with allergy and helminth infections. Although they were identified over 130 years ago, their
functions are still poorly ...understood. New insights into basophil development and function have been gained by the development of various transgenic mouse lines and staining techniques to detect and purify these cells from different organs. Several studies over the past few years have identified unexpected functions for basophils, including immunomodulatory properties and interactions with other immune cells. Here, I summarize and discuss the main findings.
Eosinophils are major effector cells during allergic responses and helminth infections. Recent studies further highlight eosinophils as important players in many other biological processes. Therefore ...it is important to understand how these cells can be modulated in terms of survival and effector function. In the present study we investigated how eosinophils respond to the alarmin IL-33. We show that IL-33 promotes eosinophil survival in a ST2- and MyD88-dependent manner. IL-33-mediated protection from apoptosis was dependent on autocrine GM-CSF release. In addition, GM-CSF increased the IL-33-induced secretion of IL-4 and IL-13 from eosinophils. Unexpectedly, this effect was further enhanced by cross-linking of Siglec-F, a proposed inhibitory and apopotosis-inducing receptor on eosinophils. Co-culture experiments with eosinophils and macrophages revealed that the IL-33-induced release of IL-4 and IL-13 from eosinophils was required for differentiation of alternatively activated macrophages (AAMs). The differentiation of AAMs could be further increased in the presence of GM-CSF. These results indicate that cross-talk between Siglec-F and the receptors for IL-33, LPS and GM-CSF plays an important role for efficient secretion of IL-4 and IL-13. Deciphering the molecular details of this cross-talk could lead to the development of new therapeutic option to treat eosinophil-associated diseases.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Parasitic worms (helminths) developed various immunoregulatory mechanisms to counteract the immune system of their host. The increasing identification and characterization of helminth-derived factors ...with strong immune modulatory activity provides novel insights into immune escape strategies of helminths. Such factors might be good targets to enhance anti-helminthic immune responses. In addition, immunosuppressive helminth-derived factors could be useful to develop new therapeutic strategies for treatment of chronic inflammatory conditions. This review will take an in depth look at the effects of immunomodulatory molecules produced by different helminths with a focus on schistosomes and mouse models of hookworm infections.
Type 2 innate lymphoid cells (ILC2s) are a major source of cytokines, which are also produced by Th2 cells and several cell types of the innate immune system. Work over the past few years indicates ...that ILC2s play a central role in regulating type 2 immune responses against allergens and helminths. ILC2s can interact with a variety of cells types of the innate and adaptive immune system by cell-cell contacts or by communication
soluble factors. In this review, we provide an overview about recent advances in our understanding how ILC2s orchestrate type 2 immune responses with focus on direct interactions between ILC2s and other cells of the immune system.
Basophils are effector cells of the innate immune system that are associated with allergic inflammation and infections with helminth parasites. However, their development and in vivo functions are ...largely unknown. Here, we characterize basophil development, turnover, tissue localization, and effector function during infection with the helminth Nippostrongylus brasiliensis. Our results demonstrate that under homeostatic conditions basophils have a lifespan of about 60 hours. N brasiliensis–induced basophilia is caused by increased de novo production of basophils in the bone marrow. Basophils were found near the marginal zone in the red pulp of the spleen, in the lamina propria of the small intestine, and in the lung parenchyma. Activated basophils promoted systemic eosinophilia, were associated with differentiation of alternatively activated macrophages in the lung, and contributed to efficient worm expulsion, demonstrating that basophils play a crucial role as effector cells in type 2 immune responses.
Basophils are associated with T helper 2 (Th2) cell-polarized immune responses such as allergic disorders or helminth infections. To directly address the role of basophils for type 2 immunity, we ...generated transgenic mice with constitutive and selective deletion of basophils. Differentiation and accumulation of Th2 cells, induction of eosinophilia, and increase in serum IgE or IgG1 induced by allergens or by infection with the helminth
Nippostrongylus brasiliensis appeared to be basophil independent. Further, basophils were not required for passive IgE- or IgG1-mediated systemic anaphylaxis. However, basophils were essential for IgE-meditated chronic allergic dermatitis and for protection against secondary infection with
N. brasiliensis. These results demonstrate that basophils play an important role for protective immunity against helminths and orchestrate chronic allergic inflammation, whereas primary Th2 cell responses can operate efficiently in the absence of this cell type.
► Constitutively basophil-ablated mice show normal Th2 responses ► Chronic allergic dermatitis depends on basophils ► Basophils are not required for humoral immune responses ► Basophils mediate protective immunity against secondary helminth infections
Gastrointestinal helminths are a major health threat worldwide. Alternatively activated macrophages (AAMs) have been shown to contribute to host protection during secondary helminth infections. AAMs ...express effector molecules that depend on activation of the IL-4- or IL-13-induced transcription factor signal transducer and activator of transcription 6 (STAT6). However, the specific role of STAT6-regulated genes like Arginase-1 (Arg1) from AAMs or STAT6-regulated genes in other cell types for host protection remains unclear. To address this point, we generated mice expressing STAT6 only in macrophages (Mac-STAT6 mouse). In the model of Heligmosomoides polygyrus bakeri (Hpb) infection, Mac-STAT6 mice could not trap larvae in the submucosa of the small intestine after secondary infection. Further, mice lacking Arg1 in hematopoietic and endothelial cells were still protected from secondary Hpb infection. On the other hand, specific deletion of IL-4/IL-13 in T cells blunted AAM polarization, activation of intestinal epithelial cells (IECs) and protective immunity. Deletion of IL-4Rα on IEC also caused loss of larval trapping while AAM polarization remained intact. These results show that Th2-dependent and STAT6-regulated genes in IECs are required and AAMs are not sufficient for protection against secondary Hpb infection by mechanisms that remain to be investigated.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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