The p38 mitogen-activated kinase pathway regulates the human interleukin-10 promoter via the activation of Sp1 transcription factor in lipopolysaccharide-stimulated human macrophages

Interleukin-10 (IL-10), a pleiotropic cytokine that inhibits inflammatory a nd cell-mediated immune responses, is produced by a wide variety of cell ty pes including T and B cells and monocytes/macrophages. Regulation of pro- a nd anti-inflammatory cytokines has been suggested to involve distinct signa ling pathways. In this study, we investigated the regulation of the human I L-10 (hIL-10) promoter in the human monocytic cell line THP-1 following act ivation with lipopolysaccharide (LPS). Analysis of hIL-10 promoter sequence s revealed that DNA sequences located between base pairs -652 and -571 are necessary for IL-10 transcription. A computer analysis of the promoter sequ ence between base pairs -652 and -571 revealed the existence of consensus s equences for Sp1, PEA1, YY1, and Epstein-Parr virus-specific nuclear antige n-2 (EBNA-2)-like transcription factors. THP-1 cells transfected with a pla smid containing mutant Sp1 abrogated the promoter activity, whereas plasmid s containing the sequences for PEA1, YY1, and EBNA-2-like transcription fac tors did not influence hIL-10 promoter activity. To understand the events u pstream of Sp1 activation, we investigated the role of p38 and extracellula r signal-regulated kinase mitogen-activated protein kinases by using their specific inhibitors. SB202190 and SB203580, the p38-specific inhibitors, in hibited LPS-induced IL-10 production. In contrast, PD98059, a specific inhi bitor of extracellular signal-regulated kinase kinases, failed to modulate IL-10 production. Furthermore, SB203580 inhibited LPS-induced activation of Sp1, as well as the promoter activity in cells transfected with a plasmid containing the Sp1 consensus sequence. These results suggest that p38 mitog en-activated protein kinase regulates LPS-induced activation of Sp1, which in turn regulates transcription of the hIL-10 gene.