title: Meprin-alpha metalloproteases enhance lipopolysaccharide-stimulated production of tumour necrosis factor-alpha and interleukin-1beta in peripheral blood mononuclear cells via activation of NF-kappaB.
abstract: Lipopolysaccharide (LPS) induces the expression of a wide range of pro-inflammatory mediators via NF-kappaB activation. These pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), may be important in triggering atherogenesis. We have previously observed that actinonin, a meprin inhibitor, suppressed the formation of atherosclerotic plaques and, in in vitro experiments, actinonin also had an effect on the way LPS altered THP-1 cell function. The aim of the present study was to investigate whether meprin-alpha regulates LPS-induced production of TNF-alpha and IL-1beta in peripheral blood mononuclear cells (PBMCs) and its potential mechanisms of action. We observed that meprin-alpha could enhance LPS-induced expression of TNF-alpha and IL-1beta mRNA and protein in a time- and concentration-dependent manner, assessed using real-time PCR and ELISA. Meprin-alpha also significantly increased LPS-induced NF-kappaB transcriptional activity. Furthermore, we assessed the effects of meprin-alpha specific siRNA on the production of TNF-alpha and IL-1beta to examine whether meprin-alpha was involved in the process of LPS-induced activation of PBMCs. Our results show that LPS-induced IL-1beta and TNF-alpha production by PBMCs was significantly reversed by meprin-alpha specific siRNA. In addition, the augmentation of meprin-alpha of the LPS-induced expression of TNF-alpha and IL-1beta was significantly decreased by Bay-117082, an inhibitor of NF-kappaB. In conclusion, our data indicate that meprin-alpha is capable of increasing LPS-induced production of cytokines in peripheral blood mononuclear cells, which might be associated with the activation of NF-kappaB.
authors.affiliation: Department of Geriatrics, No. 1 Hospital affiliated to the Third Military Medical University, Southwest Hospital, Chongqing, China, 400038.
authors.forename: Pan
authors.initials: P
authors.lastname: Gao
authors.forename: Liang-Yi
authors.initials: LY
authors.lastname: Si
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects*; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D045726:Metalloproteases / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D008625:Tiopronin / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D008625:Tiopronin; D045726:Metalloproteases