Helminth–host immunological interactions: prevention and control of immune‐mediated diseases

Abstract

Exposure to commensal and pathogenic organisms strongly influences our immune system. Exposure to helminths was frequent before humans constructed their current highly hygienic environment. Today, in highly industrialized countries, contact between humans and helminths is rare. Congruent with the decline in helminth infections is an increase in the prevalence of autoimmune and inflammatory disease. It is possible that exclusion of helminths from the environment has permitted the emergence of immune-mediated disease. We review the protective effects of helminths on expression of inflammatory bowel disease, multiple sclerosis, and animal models of these and other inflammatory diseases. We also review the immune pathways altered by helminths that may afford protection from these illnesses. Helminth exposure tends to inhibit IFN-γ and IL-17 production, promote IL-4, IL-10, and TGF-β release, induce CD4+ T cell Foxp3 expression, and generate regulatory macrophages, dendritic cells, and B cells. Helminths enable protective pathways that may vary by specific species and disease model. Helminths or their products likely have therapeutic potential to control or prevent immune-mediated illness.

Community deworming alleviates geohelminth-induced immune hyporesponsiveness

“…With respect to vaccines, there is increasing concern regarding poor immunogenicity in rural areas of developing countries (28,29); therefore, any measure to alleviate hyporesponsiveness would have a major public health impact. It is also important to consider the long-standing evolutionary coexistence between humans and helminths, the disturbance of which might lead to the emergence of pathological conditions (30). However, for this outcome, long-rather than short-term treatment courses are expected to reveal any clinical impact (31).…”

Hookworm Excretory/Secretory Products Induce Interleukin-4 (IL-4)+IL-10+CD4+T Cell Responses and Suppress Pathology in a Mouse Model of Colitis

“…Infections with live helminths from phylogenetically distant groups can protect mice against a range of autoimmune or allergic diseases (33). A growing body of literature suggests that much of this protection against inflammation is mediated by soluble molecules released by the parasites.…”

Multiple sclerosis starting before the age of 18 years: the Brazilian experience

“…Although isolated cases in our series progressed in a severe manner, the vast majority of the Brazilian patients starting MS before the age of 18 years were not particularly complicated ca ses. Theories that may account for the better disease course among Brazilian children and adolescents with MS include those relating to helminthic infections in childhood 28 , sunlight exposure 29 , and the typical national mixed race genetic background 30 . Finally, the rich variety of signs and symptoms of MS presenting during childhood and adolescence needs to be tho roughly known and understood by pediatricians 31 .…”