Dialyzable leukocyte extract differentially regulates the production of TNFalpha, IL-6, and IL-8 in bacterial component-activated leukocytes and endothelial cells.
OBJECTIVE
To investigate i) whether the Dialyzable Leukocyte Extract (DLE) modulates the production of proinflammatory cytokines in leukocytes activated by the bacterial cell wall components lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PGN); ii) the effect of DLE on LPS-stimulated endothelial cells; and iii) whether the regulatory effect of DLE on inflammatory mediators is related to the modulation of Toll-like receptors (TLRs), NF-kappaB and cAMP signaling pathways.


METHODS
Leukocytes were stimulated with LPS, LTA, and PGN in the presence of DLE. Endothelial cells were stimulated with LPS and treated with DLE. The levels of Tumor Necrosis Factor-alpha(TNFalpha), Interleukin-6 (IL-6), and IL-8 in culture supernatants were evaluated by ELISA. The expression of Toll-like receptor 2 (TLR2) and 4 (TLR4), NF-kappaB activity and cAMP levels were evaluated by flow cytometry, EMSA, and EIA, respectively.


RESULTS
The addition of DLE to leukocytes stimulated with cell wall constituents suppressed the production of TNFalpha. However, DLE induced IL-8 release in monocytes and enhanced IL-6 and IL-8 production by activated monocytes and endothelial cells. Also, DLE induced TLR2 and TLR4 expression, and increased cAMP levels, whereas NF-kappaB activity was inhibited.


CONCLUSIONS
The present data indicate the differential regulation by DLE of the production of TNFalpha, IL-6, and IL-8 cytokines, associated with effects on TLR2 and TLR4 expression and NF-kappaB and cAMP activities. We suggest a putative mechanism for the biological effects of DLE in activated leukocytes and endothelial cells.
Ojeda
Miriam Ojeda
MO
Division of Physical Chemistry, Center for Genetic Engineering and Biotechnology (CIGB), P.O. Box 6162, Havana, 10600, Cuba. miriam.ojeda@cigb.edu.cu
van't Veer
Cornelis
C
Fernández Ortega
Celia B
CB
Araña Rosainz
Manuel de J
Mde J
Buurman
Wim A
WA
D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D015850:Interleukin-6 / Q000096:biosynthesis; D016209:Interleukin-8 / Q000096:biosynthesis; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism; D010457:Peptidoglycan / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D013682:Teichoic Acids / Q000494:pharmacology*; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014165:Transfer Factor / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D018836:Inflammation Mediators; D015850:Interleukin-6; D016209:Interleukin-8; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D010457:Peptidoglycan; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D013682:Teichoic Acids; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014165:Transfer Factor; D014409:Tumor Necrosis Factor-alpha; C009900:lipoteichoic acid; D000242:Cyclic AMP