Hydrogen sulfide improves neutrophil migration and survival in sepsis via K+ATP channel activation.

RATIONALE: Recovering the neutrophil migration to the infectious focus improves survival in severe sepsis. Recently, we demonstrated that the cystathionine gamma-lyase (CSE)/hydrogen sulfide (H(2)S) pathway increased neutrophil recruitment to inflammatory focus during sterile inflammation. OBJECTIVES: To evaluate if H(2)S administration increases neutrophil migration to infectious focus and survival of mice. METHODS: Sepsis was induced by cecal ligation and puncture (CLP). MEASUREMENTS AND MAIN RESULTS: The pretreatments of mice with H(2)S donors (NaHS or Lawesson's reagent) improved leukocyte rolling/adhesion in the mesenteric microcirculation as well as neutrophil migration. Consequently, bacteremia levels were reduced, hypotension and lung lesions were prevented, and the survival rate increased from approximately 13% to approximately 80%. Even when treatment was delayed (6 h after CLP), a highly significant reduction in mortality compared with untreated mice was observed. Moreover, H(2)S pretreatment prevented the down-regulation of CXCR2 and l-selectin and the up-regulation of CD11b and G protein-coupled receptor kinase 2 in neutrophils during sepsis. H(2)S also prevented the reduction of intercellular adhesion molecule-1 expression in the endothelium of the mesenteric microcirculation in severe sepsis. Confirming the critical role of H(2)S on sepsis outcome, pretreatment with dl-propargylglycine (a CSE inhibitor) inhibited neutrophil migration to the infectious focus, enhanced lung lesions, and induced high mortality in mice subjected to nonsevere sepsis (from 0 to approximately 80%). The beneficial effects of H(2)S were blocked by glibenclamide (a ATP-dependent K(+) channel blocker). CONCLUSIONS: These results showed that H(2)S restores neutrophil migration to the infectious focus and improves survival outcome in severe sepsis by an ATP-dependent K(+) channel-dependent mechanism.

Hydrogen sulfide augments neutrophil migration through enhancement of adhesion molecule expression and prevention of CXCR2 internalization: role of ATP-sensitive potassium channels.

In this study, we have addressed the role of H(2)S in modulating neutrophil migration in either innate (LPS-challenged naive mice) or adaptive (methylated BSA (mBSA)-challenged immunized mice) immune responses. Treatment of mice with H(2)S synthesis inhibitors, dl-propargylglycine (PAG) or beta-cyanoalanine, reduced neutrophil migration induced by LPS or methylated BSA (mBSA) into the peritoneal cavity and by mBSA into the femur/tibial joint of immunized mice. This effect was associated with decreased leukocyte rolling, adhesion, and P-selectin and ICAM-1 expression on endothelium. Predictably, treatment of animals with the H(2)S donors, NaHS or Lawesson's reagent, enhanced these parameters. Moreover, the NaHS enhancement of neutrophil migration was not observed in ICAM-1-deficient mice. Neither PAG nor NaHS treatment changed LPS-induced CD18 expression on neutrophils, nor did the LPS- and mBSA-induced release of neutrophil chemoattractant mediators TNF-alpha, keratinocyte-derived chemokine, and LTB(4). Furthermore, in vitro MIP-2-induced neutrophil chemotaxis was inhibited by PAG and enhanced by NaHS treatments. Accordingly, MIP-2-induced CXCR2 internalization was enhanced by PAG and inhibited by NaHS treatments. Moreover, NaHS prevented MIP-2-induced CXCR2 desensitization. The PAG and NaHS effects correlated, respectively, with the enhancement and inhibition of MIP-2-induced G protein-coupled receptor kinase 2 expression. The effects of NaHS on neutrophil migration both in vivo and in vitro, together with CXCR2 internalization and G protein-coupled receptor kinase 2 expression were prevented by the ATP-sensitive potassium (K(ATP)(+)) channel blocker, glybenclamide. Conversely, diazoxide, a K(ATP)(+) channel opener, increased neutrophil migration in vivo. Together, our data suggest that during the inflammatory response, H(2)S augments neutrophil adhesion and locomotion, by a mechanism dependent on K(ATP)(+) channels.

Dual role of hydrogen sulfide in mechanical inflammatory hypernociception.

Hydrogen sulfide (H(2)S) is an endogenous gas involved in several biological functions, including modulation of nociception. However, the mechanisms involved in such modulation are not fully elucidated. The present study demonstrated that the pretreatment of mice with PAG, a H(2)S synthesis inhibitor, reduced LPS-induced mechanical paw hypernociception. This inhibition of hypernociception was associated with the prevention of neutrophil recruitment to the plantar tissue. Conversely, PAG had no effect on LPS-induced production of the hypernociceptive cytokines, TNF-alpha, IL-1beta and CXCL1/KC and on hypernociception induced by PGE(2), a directly acting hypernociceptive mediator. In contrast with the pro-nociceptive role of endogenous H(2)S, systemic administration of NaHS, a H(2)S donor, reduced LPS-induced mechanical hypernociception in mice. Moreover, this treatment inhibited mechanical hypernociception induced by PGE(2), suggesting a direct effect of H(2)S on nociceptive neurons. The antinociceptive mechanism of exogenous H(2)S depends on K((ATP))(+) channels since the inhibition of PGE(2) hypernociception by NaHS was prevented by glibenclamide (K((ATP))(+) channel blocker). Finally, NaHS did not alter the thermal nociceptive threshold in the hot-plate test, confirming that its effect is mainly peripheral. Taken together, these results suggest that H(2)S has a dual role in inflammatory hypernociception: 1. an endogenous pro-nociceptive effect due to up-regulation of neutrophil migration, and 2. an antinociceptive effect by direct blockade of nociceptor sensitization modulating K((ATP))(+) channels.

Rational design of novel diketoacid-containing ferrocene inhibitors of HIV-1 integrase.

Molecular interaction field, density functional, and docking studies of novel potential ferrocene inhibitors of HIV-1 integrase (IN) are reported. The high docking scores, analysis of the ligand-receptor interactions in the active site as well as the molecular interaction potential calculations at the binding site of the receptor indicate important features for novel HIV-1 IN inhibitors. We also confirm in this work a novel binding trench in HIV-1 integrase, recently reported in a theoretical work by other authors. This observation may be interesting since the lack of detailed structural information about IN-ligand interactions has hampered the design of IN inhibitors. Our proposed ligands are open to experimental synthesis and testing.

Synthesis and "in Vitro" Trypanocidal Activity Evaluation of Some Organo-iron Compounds.

Eight organo-iron ferrocene derivatives and arenocenium salts were prepared and evaluated by "in vitro" assay against one strain of Trypanosoma cruzi (Y). Six of the eight organo-iron compounds assayed, piperazinium diferrocenoate 1, eta(6)-(o-xylene)-eta(5)-(cyclopentadienyl) Iron(II) hexafluorophosphate 3, eta(6)-(mesitylene)-eta(5)-(cyclopentadienyl) iron(II) hexafluorphosphate 5, eta(6)-(durene)-eta(5)-(cyclopentadienyl) iron(II) hexafluorphosphate 6, eta(6)-(rho-chlorotoluene)-eta(5)-(cyclopentadienyl) Iron(II) hexafluorphosphate 7 and eta(6)-(chlorobenzene)-eta(5)-(cyclopentadienyl) iron(II) picrate 8 , were poorly active in the "in vitro" assays. Only two compounds 1,1'-(N-pyperidinocarbonyl) ferrocene 2(IC(50)=2.4 mug/mL) and eta(6)-(o-xylene)-eta(5)(cyclopentadienyl) iron(II) picrate 4 (IC(50)=12.08 mug/mL), were more active. Thus, some of the compounds are promising to be used against Chagas' disease as a prophylactic agents.