Regulation of interleukin-8 by interleukin-10 and transforming growth factor beta in human monocytes infected with mycobacterium bovis.
Recent studies indicate that interleukin 8 (IL-8) production contributes to the host immune responses against mycobacterial infection. In this study, we were interested to determine whether induction of IL-8 in human monocytes infected with Mycobacterium bovis was regulated by other monocyte-derived cytokines important in antimycobacterial immunity: IL-10 and transforming growth factor beta (TGF-beta). Here, we report that IL-10 reduced, in a graded and significant manner, IL-8 production by M. bovis-infected human monocytes. Additionally, the specificity of the observed inhibition was further confirmed, since the addition of an anti-IL-10 neutralizing antibody completely reversed the inhibitory effect. In contrast, addition or neutralization of TGF-beta appeared to have no significant effect on M. bovis-induced IL-8 secretion by human monocytes, whereas CD40 expression on M. bovis-infected monocytes was significantly inhibited by this cytokine. This was consistent with the finding by the reverse transcription-PCR method that pretreatment with IL-10, but not TGF-beta, potently inhibited IL-8 mRNA levels. Interestingly, neutralization of endogenous IL-10 did not significantly alter IL-8 secretion, suggesting that induction of IL-8 was not significantly affected by coexpression of IL-10 during infection of human monocytes with M. bovis. Collectively, these data indicate that IL-8 production may be regulated when human monocytes are exposed to IL-10 prior to activation with M. bovis BCG. These data will aid in our understanding of the mechanisms involved in regulating the protective immune response to stimulation with M. bovis BCG.
Méndez-Samperio
Patricia
P
Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, IPN, Carpio y Plan de Ayala, México, D.F. 11340 México. pmendezs@bios.encb.ipn.mx
García
Elizabeth
E
Vázquez
Abraham
A
Palma
Janet
J
D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D016753:Interleukin-10 / Q000494:pharmacology*; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D009000:Monocytes / Q000276:immunology / Q000382:microbiology*; D009163:Mycobacterium bovis; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D016209:Interleukin-8; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D016753:Interleukin-10