Seminars in immunopathology
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Checkpoint inhibitors blocking CTLA-4 (ipilimumab) and PD-1 (nivolumab, pembrolizumab) have transfigured our cancer treatment paradigm. However, these drugs can induce immune-related adverse events that share clinical and pathological characteristics with immune-mediated diseases. ⋯ This paper reviews the clinical, immunological, and microbiota data associated with the immune-related enterocolitis induced by the cancer immunotherapy blocking CTLA-4, ipilimumab. A parallel analysis of the mechanisms underlying inflammatory bowel diseases on the one hand, and anti-CTLA-4-induced colitis on the other hand, stresses the crucial role of the gut microbiota and of resident Treg in the genesis of both iatrogenic and spontaneous inflammatory bowel diseases.
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Allergic asthma is a worldwide increasing chronic disease of the airways which affects more than 300 million people. It is associated with increased IgE, mast cell activation, airway hyperresponsiveness (AHR), mucus overproduction and remodeling of the airways. Previously, this pathological trait has been associated with T helper type 2 (Th2) cells. ⋯ IL-9 is a pleiotropic cytokine that influences various distinct functions of different target cells such as T cells, B cells, mast cells and airway epithelial cells by activating STAT1, STAT3 and STAT5. Because of its pleiotropic functions, IL-9 has been demonstrated to be involved in several diseases, such as cancer, autoimmunity and other pathogen-mediated immune-regulated diseases. In this review, we focus on the role of Th9 and IL-9-producing cells in allergic asthma.
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Acute and chronic inflammatory responses in the lung are associated with the accumulation of large quantities of immune and structural cells undergoing apoptosis, which need to be engulfed by phagocytes in a process called 'efferocytosis'. Apoptotic cell recognition and removal from the lung is mediated predominantly by airway macrophages, though immature dendritic cells and non-professional phagocytes, such as epithelial cells and mesenchymal cells, can also display this function. Efficient clearance of apoptotic cells from the airways is essential for successful resolution of inflammation and the return to lung homeostasis. ⋯ To control the duration of the immune response and prevent autoimmune reactions, anti-inflammatory signalling cascades are initiated in the phagocyte upon apoptotic cell uptake, mediated by a range of receptors that recognise specific phospholipids or proteins externalised on, or secreted by, the apoptotic cell. However, prolonged activation of apoptotic cell recognition receptors, such as the family of receptor tyrosine kinases Tyro3, Axl and MerTK (TAM), may delay or prevent inflammatory responses to subsequent infections. In this review, we will discuss recent advances in our understanding of the mechanism controlling apoptotic cell recognition and removal from the lung in homeostasis and during inflammation, the contribution of defective efferocytosis to chronic inflammatory lung diseases, such as chronic obstructive pulmonary disease, asthma and cystic fibrosis, and implications of the signals triggered by apoptotic cells in the susceptibility to pulmonary microbial infections.
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Allergic asthma is a chronic inflammatory disease of the lower airways that affects millions of people worldwide. Allergic asthma is a T helper 2 cell (Th2)-mediated disease, in which Th2 cytokines interleukin (IL)-4, IL-5, and IL-13 are closely associated with the symptoms. IL-4 is needed by B cells to switch toward an IgE response, IL-5 recruits and activates eosinophils while IL-13 increases mucus production. ⋯ Murine studies have shown that ILC2s are an early innate source of IL-5 and IL-13 after allergen exposure, which induce airway eosinophilic infiltration, mucus hyperproduction, and airway hyperresponsiveness but not allergen-specific IgE production. ILC2s contribute to the initiation as well as to the maintenance of the adaptive type 2 immune response. Here, we review the recent progress on our understanding of the role of ILC2s in the immunopathology of allergic asthma, in particular by studies using murine models which have elucidated fundamental mechanisms by which ILC2s act.
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Adverse cutaneous drug reactions are recognized as being major health problems worldwide causing considerable costs for health care systems. Most adverse cutaneous drug reactions follow a benign course; however, up to 2% of all adverse cutaneous drug eruptions are severe and life-threatening. ⋯ Besides significant progress in clinical classification and treatment, recent studies have greatly enhanced our understanding in the pathophysiology of adverse cutaneous drug reactions. Genetic susceptibilities to certain drugs have been identified in SJS/TEN patients, viral reactivation in DRESS has been elucidated, and the discovery of tissue resident memory T cells helps to better understand the recurrent site-specific inflammation in patients with fixed drug eruption.