No extracellular IL 1B or intracellular pro IL 1B, even in the presence of 1 mM ATP, which activates NLRP 3, was detected in MSU stimulated OBs. However, OBs ex posed to MSU increased their expression Navitoclax side effects of NLRP3 protein, which peaked at 12 hours of MSU stimulation and decreased after 24 hours, as evaluated with densitom etry. Conversely, NFB is activated by solid particles ingested by OBs and by MSU in monocytic cells. Its activation was assessed through the kinetic phosphor ylation of its inhibitor IB in OBs in the presence of MSU. No modification of IB phosphorylation was detected in OBs activated by MSU, whereas TNF addition to OBs was typically associated with changes of IB phosphorylation.

Overall, these results indicate that OBs respond to MSU by a primary non conventional phagocytosis followed by a secondary autophagy, by activating NLRP3 protein without con comitant Inhibitors,Modulators,Libraries IL 1B generation, and by no signal through the NFB pathway. MSU stimulated autophagy is regulated by NLRP3 Under certain conditions like bacterial infection of macrophages, another inflammasome, the NLRC4 Ipaf inflammasome, has been reported to downregulate autophagy independent of IL 1B production. In addition, members of the NLR protein family, like NOD1 and NOD2, are intracellular sensors that in duce autophagy Inhibitors,Modulators,Libraries independent of NFB. Could NLRP3 be implicated in the regulation of autophagy activated by MSU in OBs To determine the role of NLRP3 in MSU mediated autophagy, siRNAs were used to knockdown the expression of NLRP3 in OBs. Transfec tion of OBs with a combination of two NLRP3 specific siRNAs inhibited by 44% 9% the NLRP3 expression acti vated by MSU.

In addition, the LC3 II cleav age induced by MSU was decreased by 23% 1% in NLRP3 knockdown OBs. These results indi cate that NLRP3 activated by Inhibitors,Modulators,Libraries MSU in OBs is implicated in the upregulation of autophagy. Discussion NLRP3 belongs to the family of cytosolic NLR proteins that help respond to a danger by recognition of bacterial particles, chemicals, and products from injured cells. Once activated, NLRP3 proteins associate with other cytosolic proteins to form an inflammasome presently known as a pivotal structure in the inflammatory process and in diseases in which IL 1B is greatly involved. NLRP3 activation is a hallmark of professional phagocytes involved in the immune responses. However, nonprofessional phagocytes also express NLRP3.

Interestingly, two mem bers of Inhibitors,Modulators,Libraries the NLR protein family, the intracellular sensors nucleotide binding oligomerization domain containing protein 1 and 2, are already coupled to autophagy. Here, we identify a new role for Inhibitors,Modulators,Libraries another NLR protein, NLRP3, as a positive regulator of autophagy in response to the danger signal MSU in human OBs. The functional relevance of this mechanism was shown by knockdown sellekchem of NLRP3 and by blocking the process of MSU phago cytosis, which both led to the absence of cleavage of LC3 II.