Eosinophils, a Jack of All Trades in Immunity: Therapeutic Approaches for Correcting their Functional Disorders.

BACKGROUND: Eosinophils are primitive myeloid cells which derive from bone-marrow precursors and require the intervention of interleukin (IL)-5 for their survival and persistence in blood and tissues. Under steady state conditions, they contribute to immune regulation and homeostasis. Under pathological circumstances, eosinophils are involved in both host protection against parasites and participation to allergy and inflammation. CONCLUSION: Eosinophils are cells endowed with multiple functions and their modulation with monoclonal antibodies and nutraceuticals may be effective in the treatment of chronic disease. Other: Mostly, in asthma, eosinophils provoke airway damage via release of granule contents and IL-13 with mucus hypersecretion and differentiation of Goblet cells. Then, tissue remodeling follows with secretion of transforming growth factor-beta. Eosinophils are able to kill helminth larvae acting as antigen presenting cells with involvement of T helper (h)-2 cells and subsequent antibody response. However, they also exert pro-worm activity with production of suppressive cytokine (IL-10 and IL-4) and inhibition of nitric oxide. Eosinophils may play a pathogenic role in the course of chronic and autoimmune disease, e.g., inflammatory bowel disease and eosinophilic gastroenteritis, regulating Th2 responses and promoting a profibrotic effect. In atopic dermatitis eosinophils are commonly detected and may be associated to disease severity. In cutaneous spontaneous urticaria, eosinophils participate to formation of wheals, tissue remodeling and modifications of vascular permeability. With regard to tumor growth, it seems that IgE can exert anti-neoplastic surveillance via mast cell and eosinophil-mediated cytotoxicity, the so-called allergo-oncology. From a therapeutic point of view, monoclonal antibodies directed against IL-5 or the IL-5 receptors have been shown to be very effective in patients with severe asthma. Finally, as an alternative treatment, polyphenols for their anti-inflammatory and anti-allergic activities seems to be effective in reducing serum IgE and eosinophil count in bronchoalveolar lavage in murine asthma.