The nutrition ‐gut microbiome‐physiology axis and allergic diseases
Summary
Dietary and bacterial metabolites influence immune responses. This raises the question whether the increased incidence of allergies, asthma, some autoimmune diseases, cardiovascular disease, and others might relate to intake of unhealthy foods, and the decreased intake of dietary fiber. In recent years, new knowledge on the molecular mechanisms underpinning a ‘diet‐gut microbiota‐physiology axis’ has emerged to substantiate this idea. Fiber is fermented to short chain fatty acids (SCFAs), particularly acetate, butyrate, and propionate. These metabolites bind ‘metabolite‐sensing’ G‐protein‐coupled ...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Craig McKenzie, Jian Tan, Laurence Macia, Charles R. Mackay Tags: INVITED REVIEW Source Type: research
Pathogenic T cell subsets in allergic and chronic inflammatory bowel disorders
Summary
Homeostasis in the gastrointestinal tract relies on a sensitive equilibrium between permissive and protective functions. This is closely reflected in the regulation of the intestinal immune system and especially T cells in the gut. This balance, however, is susceptible to disturbances as demonstrated by pathological conditions like food allergy, celiac disease, or inflammatory bowel disease. In these allergic and chronic inflammatory bowel disorders, luminal antigens get access to the lamina propria where they trigger a dysregulated immune response with crucial involvement of different T cell subsets. We will begin...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Sebastian Zundler, Markus F. Neurath Tags: INVITED REVIEW Source Type: research
The interplay between genetic and environmental factors in the pathogenesis of atopic dermatitis
Summary
Atopic dermatitis (AD) is a chronic skin disorder characterized by pruritus and recurrent eczematous lesions that are accompanied by T‐helper (Th)2‐dominated inflammation. AD Etiology is not yet completely understood, but it is multifactorial. Moreover, the disease is characterized by complex interactions between genetic and environmental factors, such as skin barrier dysfunctions, allergy/immunity, and pruritus. For example, filaggrin is a key protein involved in skin barrier function. Th2 cells produce interleukin (IL)‐31, which provokes pruritus, and other Th2 cytokines decrease filaggrin expression by ker...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Atsushi Otsuka, Takashi Nomura, Pawinee Rerknimitr, Judith A. Seidel, Tetsuya Honda, Kenji Kabashima Tags: INVITED REVIEW Source Type: research
Recent advances in understanding basophil ‐mediated Th2 immune responses
Summary
Basophils, the least common granulocytes, represent only ~0.5% of peripheral blood leukocytes. Because of the small number and some similarity with mast cells, the functional significance of basophils remained questionable for a long time. Recent studies using newly‐developed analytical tools have revealed crucial and non‐redundant roles for basophils in various immune responses, particularly Th2 immunity including allergy and protective immunity against parasitic infections. In this review, we discuss the mechanisms how basophils mediate Th2 immune responses and the nature of basophil‐derived factors involve...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Yoshinori Yamanishi, Kensuke Miyake, Misako Iki, Hidemitsu Tsutsui, Hajime Karasuyama Tags: INVITED REVIEW Source Type: research
Mechanisms of immune regulation in allergic diseases: the role of regulatory T and B cells
Summary
Allergy is a major public health problem with a high socio‐economic impact. The number of allergic patients is expected to reach to four billion within two decades when the World's population reaches to 10 billion. Our knowledge on the molecular mechanisms underlying allergic diseases and allergen tolerance induction had significant advances during the last years. Nowadays, it is well accepted that the generation and maintenance of allergen‐specific regulatory T cells (Tregs) and regulatory B cells (Bregs) and the involvement of their suppressive cytokines and surface molecules are essential for the induction o...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Oscar Palomares, M übeccel Akdis, Mar Martín‐Fontecha, Cezmi A. Akdis Tags: INVITED REVIEW Source Type: research
Are ILC2s Jekyll and Hyde in airway inflammation?
Summary
Asthma is a complex heterogeneous disease of the airways characterized by lung inflammation, airway hyperreactivity (AHR), mucus overproduction, and remodeling of the airways. Group 2 innate lymphoid cells (ILC2s) play a crucial role in the initiation and propagation of type 2 inflammatory programs in allergic asthma models, independent of adaptive immunity. In response to allergen, helminths or viral infection, damaged airway epithelial cells secrete IL‐33, IL‐25, and thymic stromal lymphopoietin (TSLP), which activate ILC2s to produce type 2 cytokines such as IL‐5, IL‐13, and IL‐9. Furthermore, ILC2s co...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Kafi N. Ealey, Kazuyo Moro, Shigeo Koyasu Tags: INVITED REVIEW Source Type: research
Type two innate lymphoid cells: the Janus cells in health and disease
Summary
Innate lymphoid cells are functionally diverse subsets of immune cells including the conventional natural killer cells, lymphoid tissue inducers, type 1, 2, and 3 with significant roles in immunity and pathogenesis of inflammatory diseases. Type 2 innate lymphoid cells (ILC2s) resemble type 2 helper (Th2) cells in cytokine production and contribute to anti‐helminth immunity, maintaining mucosal tissue integrity, and adipose tissue browning. ILC2s play important roles in the pathogenesis of allergic diseases and asthma. Studying the pathways of activation and regulation of ILC2s are currently a priority for giving...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Hadi Maazi, Omid Akbari Tags: INVITED REVIEW Source Type: research
IL ‐25 in allergic inflammation
Summary
IL‐25, also known as IL‐17E, is a member of the IL‐17 cytokine family mostly produced by epithelial cells and innate immune cells. After binding to the IL‐17RB/IL‐17RA complex, IL‐25 induces downstream signaling responses in epithelial cells and type 2 lymphocytes, which initiates, propagates, and sustains type 2 immunity. The function of IL‐25 in allergic diseases such as asthma has been well established, and now also is extended to diseases such as inflammatory bowel disease and cancer. This review summarizes the literature on IL‐25 and discusses the unsolved questions. Our knowledge on IL‐25 wi...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Miao Xu, Chen Dong Tags: INVITED REVIEW Source Type: research
IL ‐33: biological properties, functions, and roles in airway disease
Summary
Interleukin (IL)‐33 is a key cytokine involved in type 2 immunity and allergic airway diseases. Abundantly expressed in lung epithelial cells, IL‐33 plays critical roles in both innate and adaptive immune responses in mucosal organs. In innate immunity, IL‐33 and group 2 innate lymphoid cells (ILC2s) provide an essential axis for rapid immune responses and tissue homeostasis. In adaptive immunity, IL‐33 interacts with dendritic cells, Th2 cells, follicular T cells, and regulatory T cells, where IL‐33 influences the development of chronic airway inflammation and tissue remodeling. The clinical findings tha...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Li Yin Drake, Hirohito Kita Tags: INVITED REVIEW Source Type: research
Innate and adaptive type 2 immunity in lung allergic inflammation
Summary
Allergic inflammation is a type 2 immune disorder classically characterized by high levels of immunoglobulin E (IgE) and the development of Th2 cells. Asthma is a pulmonary allergic inflammatory disease resulting in bronchial hyper‐reactivity. Atopic asthma is defined by IgE antibody‐mediated mast cell degranulation, while in non‐atopic asthma there is no allergen‐specific IgE and more involvement of innate immune cells, such as basophils, group 2 innate lymphoid cells (ILC2), and eosinophils. Recently, protease allergens were shown to cause asthmatic responses in the absence of Th2 cells, suggesting that a...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Masato Kubo Tags: INVITED REVIEW Source Type: research
Allergic airway inflammation: key players beyond the Th2 cell pathway
Summary
Allergic asthma is characterized by eosinophilic airway inflammation, mucus hyperproduction, and airway hyperreactivity, causing reversible airway obstruction. Accumulating evidence indicates that antigen‐specific Th2 cells and their cytokines such as IL‐4, IL‐5, and IL‐13 orchestrate these pathognomonic features of asthma. However, over the past decade, the understanding of asthma pathogenesis has made a significant shift from a Th2 cell‐dependent, IgE‐mediated disease to a more complicated heterogeneous disease. Recent studies clearly show that not only Th2 cytokines but also other T cell‐related cy...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Koichi Hirose, Arifumi Iwata, Tomohiro Tamachi, Hiroshi Nakajima Tags: INVITED REVIEW Source Type: research
Interplay between barrier epithelial cells and dendritic cells in allergic sensitization through the lung and the skin
This articles reviews the different players involved in the initiation of allergic reactions in the lung and in the skin, and highlights the importance of a crosstalk between antigen‐presenting dendritic cells and structural cell‐derived signals in this process. Our increasing understanding of these mechanisms indicates that structural cells, such as airway epithelial cells and skin keratinocytes, need to be considered as more than a simple physical barrier since they are very upstream of the entire Th2 cascade and therefore might represent crucial targets for new therapies. (Source: Immunological Reviews)
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Julie Deckers, Karolien De Bosscher, Bart N Lambrecht, Hamida Hammad Tags: INVITED REVIEW Source Type: research
The atopic march: current insights into skin barrier dysfunction and epithelial cell ‐derived cytokines
Summary
Atopic dermatitis often precedes the development of other atopic diseases. The atopic march describes this temporal relationship in the natural history of atopic diseases. Although the pathophysiological mechanisms that underlie this relationship are poorly understood, epidemiological and genetic data have suggested that the skin might be an important route of sensitization to allergens. Animal models have begun to elucidate how skin barrier defects can lead to systemic allergen sensitization. Emerging data now suggest that epithelial cell‐derived cytokines such as thymic stromal lymphopoietin (TSLP), IL‐33, an...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Hongwei Han, Florence Roan, Steven F. Ziegler Tags: INVITED REVIEW Source Type: research
Development of allergic immunity in early life
Summary
The growth and maturity of the peripheral immune system and subsequent development of pulmonary immunity in early life is dictated by host, environmental and microbial factors. Dysregulation during the critical window of immune development in the postnatal years results in disease which impacts on lifelong lung health. Asthma is a common disease in childhood and is often preceded by wheezing illnesses during the preschool years. However, the mechanisms underlying development of wheeze and how and why only some children progress to asthma is unknown. Human studies to date have generally focused on peripheral immune ...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Clare M. Lloyd, Sejal Saglani Tags: INVITED REVIEW Source Type: research
Crucial role for CD69 in allergic inflammatory responses: CD69 ‐Myl9 system in the pathogenesis of airway inflammation
Summary
CD69 has been known as an early activation marker of lymphocytes; whereas, recent studies demonstrate that CD69 also has critical functions in immune responses. Early studies using human samples revealed the involvement of CD69 in various inflammatory diseases including asthma. Moreover, murine disease models using Cd69−/− mice and/or anti‐CD69 antibody (Ab) treatment have revealed crucial roles for CD69 in inflammatory responses. However, it had not been clear how the CD69 molecule contributes to the pathogenesis of inflammatory diseases. We recently elucidated a novel mechanism, in which the interaction bet...
Source: Immunological Reviews - June 28, 2017 Category: Allergy & Immunology Authors: Motoko Y. Kimura, Koji Hayashizaki, Koji Tokoyoda, Shiki Takamura, Shinichiro Motohashi, Toshinori Nakayama Tags: INVITED REVIEW Source Type: research
