About this Research Topic
Circulating basophilic granulocytes are hematopoietic cells found in various animals including several species of invertebrates such as bivalves, spiders, and crabs. In mammals, they are rare cells able to quickly release diverse potent preformed mediators and to produce diverse bioactive molecules. This includes monoamines (i.e. histamine), growth factors and cytokines (including interleukin 4), enzymes (several proteases), lipid mediators (leukotrienes and prostanoids), glycans (various glycosaminoglycans and heparin), and extracellular traps. The diversity and relative specificity of their secretome suggest basophils can act as both effectors and cells involved in intercellular communication. Their functions have been mostly studied on rodent models: it is now accepted that “basophils” can play a non-redundant role in some models of type 2 immunity. Particularly, they show a protective role during helminth infections or tick infestations and a pathogenic role in specific allergic or autoimmune diseases. Beyond type 2 immunity, basophils display some bactericidal properties and promote pathogenic Th17 responses.
Basophils express high levels of FcεRIα, the high-affinity receptor for immunoglobulin E (IgE), which mediates their degranulation after secondary exposure to a pathogen or allergen and promotes their hematopoiesis. Basophils IgE crosslinking is important for protective immunity against ticks and helminths, and for the development of various deleterious conditions: several allergic diseases including atopic dermatitis, asthma, chronic rhinosinusitis or food allergy, and some autoimmune diseases including systemic lupus erythematosus. In terms of evolution, antibody-mediated basophil degranulation arises before the appearance of IgE. Degranulation can be induced by other types of immunoglobulins, or without immunoglobulins, in fish, rodents, and Humans. Importantly, basophils show an antibody-independent regulation during infection, inflammation, allergic diseases, or autoimmunity. These “innate” functions can be pro-inflammatory (secretion of pro-inflammatory cytokines and lipid mediators), immunoregulatory (Th2, Th17, B cell class switching), or pro-resolution in various inflammatory contexts (including damage, allergy, and infection). This “innate” activation can be induced by diverse stimuli, including but not limited to microbial or damage-associated patterns, alarmins, eicosanoids, proteases, complement, and cytokines (especially interleukin 3).
Unraveling the complex mechanisms governing basophils beneficial or deleterious functions may help us to understand their ancestral role in immunity and beyond, in “non-immune” physiological processes. The philosophy behind this Research Topic is to gather a broad knowledge and points of view on basophils fundamental biology by regrouping several types of articles including Original Research, Brief Research Report, Data Report, Systematic Review, Review, Mini Review, Methods, Hypothesis and Theory, Perspective or Opinion. Articles from a wide array of specialties that study “circulating basophilic granulocytes” in any animal species are welcome. This includes articles treating:
• The population level such as Epidemiology, Immunogenetics or Evolutionary Immunology
• The organism level such as Systems Biology, Microbiome – Immune crosstalks, Physiology, and Physiopathology, Allergy and Autoimmunity
• The organ level such as Infectious Diseases, Inflammation, Neuroimmunology, Fibrosis, and Remodeling
• The cellular level such as Cell Biology, Hematopoiesis, Intercellular communications
• The molecular level such as Multi-Omics and Cell Signaling
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