Abstract
BackgroundIn sub-Saharan Africa poly-parasite infections are frequently observed in children, and with poly-parasitism modulating immune mechanisms, mediated by cytokines and chemokines, are required to prevent overwhelming inflammation and host tissue damage. We analyzed in children co-infected with helminthes and protozoan parasites their cellular production of regulatory and pro-inflammatory cytokines and chemokines in response to parasite antigens and allergens.MethodsIntestinal and intravascular parasite infections were detected in stool and urines samples. The in vitro cellular cytokine and chemokine responses of peripheral blood mononuclear cells (PBMC) to parasite antigens and allergens were analysed in children (n = 87) with single and poly-parasite infection, and skin prick test reactivity to fungus and mite allergens was determined in singly and poly-parasitized children (n = 509).ResultsIn children Entamoeba histolytica/dispar (62%), Necator americanus (31%), Schistosoma haematobium (28%), S. mansoni (21%), Hymenolepis nana (2%) and Strongyloides stercoralis (1%) were diagnosed. Singly infected were 37%, 47% were positive for 2 or more parasite species and 16% were infection-free. When PBMC were stimulated in vitro with parasite antigens and allergens, regulatory-type cytokine IL-27 and alarmin-type IL-33 enhanced with poly-parasite infections whilst IL-10 and pro-inflammatory MIP3-α/CCL20 and MIG/CXCL9 were produced in similar amounts in singly or poly-parasitized children. The co-stimulation in vitro of PBMC with mite allergens and Ascaris lumbricoides antigens depressed the allergen-induced pro-inflammatory IL-27, IL-33 and MIP3-α/CCL20 responses while regulatory IL-10 remained unaffected. Post albendazole and/or praziquantel treatment, the cellular release of IL-10, IL-33, MIP3-α/CCL20 and MIG/CXCL9 lessened significantly in all children infection groups. Skin prick test (SPT) reactivity to fungus Aspergillus fumigatus and mite Dermatophagoides pteronyssinus allergens was investigated in 509 children, and positive SPT responses were found in 23% of the infection-free, and in 47%, 53% and 56% of the singly, doubly and poly-parasite infected, respectively.ConclusionsIn children co-infected with helminthes and protozoan parasites a mixed cellular response profile of both inflammatory and regulatory chemokines and cytokines was stimulated by individual antigens and allergens, pro-inflammatory cytokines and chemokines enhanced with an increasing number of parasite infections, and in poly-parasitized children skin prick test reactivity to allergens extracts was highest.
Highlights
In sub-Saharan Africa poly-parasite infections are frequently observed in children, and with poly-parasitism modulating immune mechanisms, mediated by cytokines and chemokines, are required to prevent overwhelming inflammation and host tissue damage
For stool and urine examinations, 50-mL polypropylene tubes were distributed to the pupils and collected the morning; diagnostic procedures were performed by the laboratory staff at the Centre Hospitalier Régional (CHR), Sokodé
The present study revealed in children infected with helminthes and protozoan parasites distinctive cellular cytokine and chemokine response profiles to antigens of protozoa, helminthes, bacteria and allergens
Summary
In sub-Saharan Africa poly-parasite infections are frequently observed in children, and with poly-parasitism modulating immune mechanisms, mediated by cytokines and chemokines, are required to prevent overwhelming inflammation and host tissue damage. Intravascular parasite infections were described to ameliorate and even prevented allergen induced skin sensitization in humans [17] as well as airway hyper-reactivity in experimental animal studies [18] Such an immune modulating capacities of pathogens has been extended to situations without active infection where exposure to environmental non-viable microbial products sufficed to reduce the occurrence of hay fever, atopic asthma, and atopic sensitization to environmental allergens [19] In children, poly-parasite infections with S. haematobium/S. mansoni, E. histolytica/E. dispar, and N. americanus generated prominent pro-inflammatory cytokine and chemokine responses, and anti-helminth treatment lessened inflammatory chemokine responses whilst the Th2 responsiveness in co-infected children increased [5]. Long-term periodic anti-helminth treatments were associated with an increased prevalence of allergen skin test reactivity [20] and eczema symptoms [21]
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