Probucol attenuates lipopolysaccharide-induced leukocyte recruitment and inflammatory hyperalgesia: effect on NF-кB activation and cytokine production.

Probucol 4,4'- (Isopropylidenedithio)bis(2,6-di-tert-butylphenol) is a synthetic molecule clinically used for prevention and treatment of hypercholesterolemia and atherosclerosis. Recent studies have shown that the beneficial effects of probucol mainly derive from its anti-inflammatory and antioxidant properties. Gram-negative bacteria are common infectious agents and their wall components, e.g. lipopolysaccharide (LPS), are important elicitors of inflammation. LPS is sensed by tissue resident cells and it triggers a Toll-like receptor 4/MyD88-dependent signaling cascade resulting in endothelial activation, leukocyte recruitment and nociception. Therefore the present study aimed to investigate the anti-inflammatory and analgesic effects of probucol in models of LPS-induced acute inflammation. Probucol at 0.3-30mg/kg was administrated to male Swiss mice per oral 1h before intraplantar or intraperitoneal lipopolysaccharide stimulus. Probucol at 3mg/kg reduced lipopolysaccharide-induced mechanical and thermal hyperalgesia. These effects were accompanied by reduced leukocyte influx and cytokine production in both paw skin and peritoneum exudate. Unexpectedly, probucol did not alter lipopolysaccharide-induced tissue oxidative stress at anti-inflammatory /analgesic dose. On the other hand, probucol inhibited lipopolysaccharide-induced nuclear factor kappa B (NF-кB) activation in paw tissue as well as NF-кB activity in cultured macrophages in vitro, reinforcing the inhibitory effect of probucol over the NF-кB signaling pathway. In this sense, we propose that probucol acts on resident immune cells, such as macrophages, targeting the NF-кB pathway. As a result, it prevents the amplification and persistence of the inflammatory response by attenuating NF-кB-dependent cytokine production and leukocyte recruitment explaining its analgesic effects as well.

Neovestitol, an isoflavonoid isolated from Brazilian red propolis, reduces acute and chronic inflammation: involvement of nitric oxide and IL-6.

Isoflavonoids have been largely studied due to their distinct biological activities identified thus far. Herein, we evaluated the activity of neovestitol, an isoflavonoid isolated from Brazilian red propolis, in acute and chronic inflammation. As for acute inflammation, we found that neovestitol reduced neutrophil migration, leukocyte rolling and adhesion, as well as expression of ICAM-1 in the mesenteric microcirculation during lipopolysaccharide-induced acute peritonitis. No changes were observed in the levels of TNF-α, CXCL1/KC and CXCL2/MIP-2 upon pretreatment with neovestitol. The administration of an inducible nitric oxide synthase (iNOS) inhibitor abolished the inhibitory effects of neovestitol in neutrophil migration and ICAM-1 expression. Nitrite levels increased upon treatment with neovestitol. No effects of neovestitol were observed on the chemotaxis of neutrophils in vitro. As for chronic inflammation, neovestitol also reduced the clinical score and joint damage in a collagen-induced arthritis model. There was no change in the frequency of IL-17-producing TCD4+ cells. In addition, pretreatment with neovestitol reduced the levels of IL-6. These results demonstrate a potential anti-inflammatory activity of neovestitol, which may be useful for therapeutic purposes and/or as a nutraceutical.

Fructose 1,6-bisphosphate, a high-energy intermediate of glycolysis, attenuates experimental arthritis by activating anti-inflammatory adenosinergic pathway.

Fructose 1,6-bisphosphate (FBP) is an endogenous intermediate of the glycolytic pathway. Exogenous administration of FBP has been shown to exert protective effects in a variety of ischemic injury models, which are attributed to its ability to sustain glycolysis and increase ATP production. Here, we demonstrated that a single treatment with FBP markedly attenuated arthritis, assessed by reduction of articular hyperalgesia, joint swelling, neutrophil infiltration and production of inflammatory cytokines, TNF and IL-6, while enhancing IL-10 production in two mouse models of arthritis. Our mechanistic studies showed that FBP reduces joint inflammation through the systemic generation of extracellular adenosine and subsequent activation of adenosine receptor A2a (A2aR). Moreover, we showed that FBP-induced adenosine generation requires hydrolysis of extracellular ATP through the activity of the ectonucleosides triphosphate diphosphohydrolase-1 (ENTPD1, also known as CD39) and ecto-5'-nucleotidase (E5NT, also known as CD73). In accordance, inhibition of CD39 and CD73 abolished anti-arthritic effects of FBP. Taken together, our findings provide a new insight into the molecular mechanism underlying the anti-inflammatory effect of FBP, showing that it effectively attenuates experimental arthritis by activating the anti-inflammatory adenosinergic pathway. Therefore, FBP may represent a new therapeutic strategy for treatment of rheumatoid arthritis (RA).