Μελέτη της αλληλεπίδρασης του NALP3 ενδοκυττάριου υποδοχέα μετους διαμεμβρανικούς Toll-like υποδοχείς για την επαγωγή αντιδράσεων φυσικής ανοσίας

NALP3 protein belongs to the NLR (NOD-LRR) receptor family, a recently described cytosolic pattern recognition receptor (PRR) system. In contrast to the transmembrane Toll-like receptors (TLRs) that function through transcriptional activation of inflammatory genes, this kind of receptors are essential for the maturation of precursors of crucial proinflammatory cytokines. In response to various signals, NALP3 forms a multiprotein complex, called NALP3-inflammasome, that activates the proinflammatory caspase-1 that subsequently proceed the maturation of interleukine-1β (IL-1β) and IL18. Excessive production of these cytokines is associated with septic shock and autoimmune disorders. Several studies have provided evidence that NLR and TLR pathways work in synergy to bring about intracellular responses. In this project we study the interplay between TLRs and NLRs in the induction of innate immune responses. For this purpose, we use macrophages from C57BL/6 and NALP3 deficient mice and assess the phosphorylation of molecules downstream of these pathways, as well as the expression of target genes, such as chemokines and anti- and inflammatory cytokines. Furthermore, we exam the role of NALP3 protein in the LPS tolerance phenomenon, which is the development of a state of refractoriness to a second stimulation in cells treated with lipopolysaccharide (LPS). Since many studies have provided evidence that there is impaired antigen presentation by cells of immune system during LPS tolerance, we examed the expression of MHC (major histocompatibility comlex) molecules in NALP3 knock out macrophages during the phenomenon. Although we did not detect any differences in the expression of these molecules between C57BL/6 and NALP3 deficient macrophages during LPS tolerance, we observed decreased upregulation of MHC molecules after the first treatment with LPS. Our results indicate that NALP3 protein may have a role in antigen presentation and in the activation of adaptive immunity. The clarification of the mechanisms by which PRRs communicate is obligatory for understanding the induction of immune responses. Our study provides valuable information for the crosstalk between the cytosolic NALP3 and the transmembrane TLR receptors not only as innate immune responses are concerned but also for the mechanisms that bridge innate and acquired immunity. By combining all the above, our work provide a clearer insight into the function of this novel key regulatory molecule of immune responses that can be considered as a potential novel anti-inflammatory approach