Restricted entry of R5 HIV Type 1 strains into eosinophilic cells

Eosinophils as Major Player in Type 2 Inflammation: Autoimmunity and Beyond

Eosinophils are a subset of differentiated granulocytes which circulate in peripheral blood and home in several body tissues. Along with their traditional relevance in helminth immunity and allergy, eosinophils have been progressively attributed important roles in a number of homeostatic and pathologic situations. This review aims at summarizing available evidence about eosinophils functions in homeostasis, infections, allergic and autoimmune disorders, and solid and hematological cancers.Their structural and biological features have been described, along with their physiological behavior. This includes their chemokines, cytokines, granular contents, and extracellular traps. Besides, pathogenic- and eosinophilic-mediated disorders have also been addressed, with the aim of highlighting their role in Th2-driven inflammation. In allergy, eosinophils are implicated in the pathogenesis of atopic dermatitis, allergic rhinitis, and asthma. They are also fundamentally involved in autoimmune disorders such as eosinophilic esophagitis, eosinophilic gastroenteritis, acute and chronic eosinophilic pneumonia, and eosinophilic granulomatosis with polyangiitis. In infections, eosinophils are involved in protection not only from parasites but also from fungi, viruses, and bacteria. In solid cancers, local eosinophilic infiltration is variably associated with an improved or worsened prognosis, depending on the histotype. In hematologic neoplasms, eosinophilia can be the consequence of a dysregulated cytokine production or the result of mutations affecting the myeloid lineage.Recent experimental evidence was thoroughly reviewed, with findings which elicit a complex role for eosinophils, in a tight balance between host defense and tissue damage. Eventually, emerging evidence about eosinophils in COVID-19 infection was also discussed.

Eosinophils from Physiology to Disease: A Comprehensive Review

Despite being the second least represented granulocyte subpopulation in the circulating blood, eosinophils are receiving a growing interest from the scientific community, due to their complex pathophysiological role in a broad range of local and systemic inflammatory diseases as well as in cancer and thrombosis. Eosinophils are crucial for the control of parasitic infections, but increasing evidence suggests that they are also involved in vital defensive tasks against bacterial and viral pathogens including HIV. On the other side of the coin, eosinophil potential to provide a strong defensive response against invading microbes through the release of a large array of compounds can prove toxic to the host tissues and dysregulate haemostasis. Increasing knowledge of eosinophil biological behaviour is leading to major changes in established paradigms for the classification and diagnosis of several allergic and autoimmune diseases and has paved the way to a "golden age" of eosinophil-targeted agents. In this review, we provide a comprehensive update on the pathophysiological role of eosinophils in host defence, inflammation, and cancer and discuss potential clinical implications in light of recent therapeutic advances.

IgE-FcepsilonRI interactions determine HIV coreceptor usage and susceptibility to infection during ontogeny of mast cells

Progenitor mast cells (prMCs), derived from CD34(+) precursors are CD4(+)/CCR5(+)/CXCR4(+) and susceptible to CCR5(R5)-tropic virus but only marginally susceptible to CXCR4(X4)-tropic HIV. As infected prMCs mature within extravascular compartments, they become both latently infected and HIV-infection resistant, and thus capable of establishing an inducible reservoir of CCR5-tropic infectious clones. In this report we provide the first evidence that IgE-FcepsilonRI interactions, occurring during a unique period of mast cell (MC) ontogeny, enhance prMC susceptibility to X4 and R5X4 virus. IgE-FcepsilonRI interactions significantly increased expression of CXCR4 mRNA ( approximately 400- to 1800-fold), enhanced prMC susceptibility to X4 and R5X4 virus ( approximately 3000- to 16,000-fold), but had no significant effect on CD4, CCR3, or CCR5 expression, susceptibility to R5 virus, or degranulation. Enhanced susceptibility to infection with X4 virus occurred during the first 3-5 wk of MC ontogeny and was completely inhibited by CXCR4-specific peptide antagonists and omalizumab, a drug that inhibits IgE-FcepsilonRI interactions. IgE-FcepsilonRI coaggregation mediated by HIVgp120 or Schistosoma mansoni soluble egg Ag accelerated maximal CXCR4 expression and susceptibility to X4 virus by prMCs. Our findings suggest that for HIV-positive individuals with atopic or helminthic diseases, elevated IgE levels could potentially influence the composition of CXCR4-tropic and R5X4-tropic variants archived within the long-lived tissue MC reservoir created during infection.