Low cellular cholesterol increases the effect of Lactobacillus reuteri 1098 on TNF-α production

SORIA MA, FONT DE VALDEZ G, RODRIGUEZ AV

San Miguel de Tucumán, Argentina

Simposio; II International Symposium on Lactic Acid Bacteria. First Argentinean Lab Net Meeting.; 2006

CERELA-CONICET

LOW CELLULAR CHOLESTEROL INCREASES THE EFFECT OF Lactobacillus reuteri  CRL 1098 ON TNF-α PRODUCTION. Soria M. A., Font de Valdéz G., Rodriguez A.V. Centro de Referencia para Lactobacilos (CERELA). Chacabuco 145. 4000-Tucumán, Argentina. E-mail: anavirr@cerela.org.ar   Lipid rafts are plasma membrane microdomains of eukaryotic cells rich in cholesterol, sphingolipids and GPI-proteins. These microdomains concentrate several receptors and are involved in signaling transduction. In addition, they are the target for different microorganims to control the cellular response. The aim of this work was to investigate L. reuteri CRL 1098 effect on TNF-α production by peripheral blood mononuclear cells (PBMC). Cellular response of PBMC with modified lipid rafts by cholesterol depletion was studied. PBMC cholesterol levels were depleted with 10 mM methyl-ß-cyclodextrin and determined by Filipin stain. Control PBMC (without treatment) and with depeleted cholesterol were incubated with L. reuteri at different multiplicity of infection (MOI=CFU/cells number) and times of incubation. In some experiments PBMC were incubated with the fractions of supernatant of L. reuteri which was submitted to ultrafiltration through Centricon 10 kDa membranes: fractions I (molecules < 10 kDa) and II (molecules >10 kDa). TNF-α was determined by chemisluminiscent assay in supernatant of PBMC-L. reuteri and PBMC-fractions I or II cultures. The TNF-α value obtained was 149 pg /1x106 cells. In control cells incubated with L. reuteri at 20 MOI for 4 h, this value was reduced by 27%. PBMC with low cholesterol incubated in the same conditions showed a reduction of 51%. When PBMC were incubated in fraction I of L. reuteri supernatant TNF-α value diminished by 41 and 63 % in control and low cholesterol cells respectively, while no differences were observed in cells incubated in fraction II.