Protective effect of gedunin on TLR-mediated inflammation by modulation of inflammasome activation and cytokine production: Evidence of a multitarget compound.

Activation of toll-like receptors (TLRs) by pathogen-associated molecular patterns (PAMPs) triggers an innate immune response, via cytokine production and inflammasome activation. Herein, we have investigated the modulatory effect of the natural limonoid gedunin on TLR activation in vitro and in vivo. Intraperitoneal (i.p.) pre- and post-treatments of C57BL/6 mouse with gedunin impaired the influx of mononuclear cells, eosinophils and neutrophils, as well as the production of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and nitric oxide (NO), triggered by lipopolysaccharide (LPS) in mouse pleura. Accordingly, in vitro post-treatment of immortalized murine macrophages with gedunin also impaired LPS-induced production of such mediators. Gedunin diminished LPS-induced expression of the nucleotide-binding domain and leucine-rich repeat protein-3 (NLRP3) on pleural leukocytes in vivo and in immortalized macrophages in vitro. In line with this, gedunin inhibited LPS-induced caspase-1 activation and the production of IL-1ß in vivo and in vitro. In addition, gedunin treatment triggered the generation of the anti-inflammatory factors IL-10 and heme oxigenase-1 (HO-1) at resting conditions or upon stimulation. We also demonstrate that gedunin effect is not restricted to TLR4-mediated response, since this compound diminished TNF-α, IL-6, NO, NLRP3 and IL-1ß, as well as enhanced IL-10 and HO-1, by macrophages stimulated with the TLR2 and TLR3 agonists, palmitoyl-3-Cys-Ser-(Lys)4 (PAM3) and polyriboinosinic:polyribocytidylic acid (POLY I:C), in vitro. In silico modeling studies revealed that gedunin efficiently docked into caspase-1, TLR2, TLR3 and to the myeloid differentiation protein-2 (MD-2) component of TLR4. Overall, our data demonstrate that gedunin modulates TLR4, TLR3 and TLR2-mediated responses and reveal new molecular targets for this compound.

1-Aryl-1H- and 2-aryl-2H-1,2,3-triazole derivatives blockade P2X7 receptor in vitro and inflammatory response in vivo.

Fifty-one 1,2,3-triazole derivatives were synthesized and evaluated with respect to P2X7 receptor (P2X7R) activity and its associated pore. These triazoles were screened in vitro for dye uptake assay and its cytotoxicity against mammalian cell types. Seven 1,2,3-triazole derivatives (5e, 6e, 8h, 9d, 9i, 11, and 12) potently blocked P2X7 receptor pore formation in vitro (J774.G8 cells and peritoneal macrophages). All blockers displayed IC50 value inferior to 500 nM, and they have low toxicity in either cell types. These seven selected triazoles inhibited P2X7R mediated interleukin-1 (IL-1ß) release. In particular, compound 9d was the most potent P2X7R blocker. Additionally, in mouse acute models of inflammatory responses induced by ATP or carrageenan administration in the paw, compound 9d promoted a potent blocking response. Similarly, 9d also reduced mouse LPS-induced pleurisy cellularity. In silico predictions indicate this molecule appropriate to develop an anti-inflammatory agent when it was compared to commercial analogs. Electrophysiological studies suggest a competitive mechanism of action of 9d to block P2X7 receptor. Molecular docking was performed on the ATP binding site in order to observe the preferential interaction pose, indicating that binding mode of the 9d is by interacting its 1,2,3-triazole and ether moiety with positively charged residues and with its chlorobenzene moiety orientated toward the apolar end of the ATP binding site which are mainly composed by the Ile170, Trp167 and Leu309 residues from α subunit. These results highlight 9d derivative as a drug candidate with potential therapeutic application based on P2X7 receptor blockade.