Interleukin-6 treatment enhances human monocyte permissiveness for Paracoccidioides brasiliensis growth by modulating cytokine production.
The effect of interleukin (IL)-6 on cytokine production was evaluated in human monocyte cultures infected with the virulent strain of Paracoccidioides brasiliensis (Pb18). Peripheral blood monocytes from healthy individuals were preincubated for 24 h with or without human recombinant IL-6, and then challenged with Pb18 for 4 h and 18 h. P. brasiliensis growth was assessed by viable fungi recovery from co-cultures after plating on BHI-agar. Moreover, tumor necrosis factor-alpha (TNF-alpha), IL-6 and IL-10 production in supernatant cultures was determined by enzyme immunoassay (ELISA). Monocyte preincubation with IL-6, and challenged with Pb18 for 4 h, led to significantly higher fungi recovery compared to non-treated co-cultures. The pretreatment of monocytes with IL-6 induced an inhibitory effect on TNF-alpha and IL-10 production during 18 h fungal infection. Otherwise, an autocrine stimulatory effect on IL-6 production was detected at 4 h and 18 h as represented by an elevation in IL-6 levels. The reduction in TNF-alpha levels and stimulation of IL-6 production induced by previous IL-6 treatment might be responsible for a significant increase in fungal growth in human monocytes. The results suggest that IL-6, by exerting a modulatory effect on cytokines production, makes monocyte more permissive for fungal growth.
Siqueira
Keila Zaniboni
KZ
Department of Microbiology and Immunology, Institute of Biosciences, Sao Paulo State University, Botucatu, SP, Brazil.
Campos Soares
Angela Maria Victoriano De
AM
Dias-Melicio
Luciane Alarcão
LA
Calvi
Sueli Aparecida
SA
Peraçoli
Maria Terezinha Serrão
MT
D000328:Adult; D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D016753:Interleukin-10 / Q000378:metabolism; D015850:Interleukin-6 / Q000276:immunology*; D008297:Male; D050296:Microbial Viability; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology* / Q000382:microbiology*; D010228:Paracoccidioides / Q000254:growth & development* / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D055815:Young Adult
D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10