TLR2 LIGATION IN HUMAN MACROPHAGES TRIGGERS A SPECIFIC, DEFAULT, LATE PHASE AND SUSTAINED CYTOSOLIC RESPONSE

RODOLFO C GARCÍA; CRISTIAN JORGE ALEJANDRO ASENSIO

Mar del Plata

Congreso; LXI REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC); 2016

SAIC

TLR receptors are part of the defence against microorganisms and also endogenous inflammatory insults. It is not completely known how the specific responses of each member of this family are controlled during the concomitant activation of other immune/inflammatory receptors including those of the family. Since different receptors share multiple cytoplasmic signalling proteins along different pathways it remains a main question to know if any specific signalling is possible for each receptor. To study the spatio-temporal regulation of TLR receptors we focussed on the study of the proteome responses of the THP-1 human macrophage cell line. We stimulated these cells with 3 different bacterial species (live and killed) and with pure TLR2/TLR4 ligands. In order to detect reproducible changes in protein markers we employed novel biochemical techniques to compare the cytoplasmic proteome profiles after different stimuli. We achieved enhanced sensitivity compared with the traditional gel staining techniques. Among many proteome alterations, we detected a specific response to TLR2 ligation in the cytosol showing a very reproducible temporal behaviour. It is a default response which persist for days proportionally to the half life and abundance of TLR2 ligands. Besides, the response is not affected by the concomitant activation of other inflammatory or cell stress pathways. Concomitant bacterial infection or TLR4 activation cannot modify this response to TLR2 ligation. We propose this response as a specific proteomic biomarker of TLR2 ligation. The results suggest that ligation of TLR2, by any ligand regardless of its structure, triggers the same cytosolic response with the participation of microtubules and a chaperone which is post-translationally modified in a reproducible manner and timing. Using novel proteomic strategies we demonstrate that TLR2, with the participation of cytosolic protein complexes, monitors continuously the presence of its ligands in macrophages