An increase in nitric oxide produced by rat peritoneal neutrophils is not involved in cell apoptosis

Polymorphonuclear neutrophils (PMN) obtained from carrageenin-stimulated peritoneal cavities of rats, but not blood PMN, spontaneously produced nitric oxide (NO) when incubated in vitro. Incubation of the cells with the NO synthase inhibitors, L-imino-ethyl-L-ornithine (L-NIO) or NG-monomethyl-L-arginine (L-NMMA), inhibited NO production. This inhibition could be reversed by L-arginine. Incubation of PMN with lipopolysaccharide (LPS) failed to enhance NO production. Pretreatment of the rats with dexamethasone (DEXA) prior to carrageenin injection or incubation of PMN with the glucocorticoid in vitro partially inhibited the spontaneous release of NO. On the other hand, when PMN obtained from DEXA pretreated rats were incubated in vitro with DEXA, NO synthase activity and hence NO generation were almost abolished. A similar inhibition was also observed following the addition of L-NIO or cycloheximide to cultures of carrageenin-elicited PMN. The NO production by PMN did not appear to be related to cell viability or apoptosis. Indeed, neither the blockade of NO generation by L-NIO nor the incubation of the neutrophils with a NO donor, S-nitroso-acetylpenicillamine (SNAP) modified the pattern of LDH release or DNA fragmentation. In summary, it appears that PMN migration triggers a continuous NO synthesis, and that NO produced by these cells is not related to their apoptosis

Snake Venom Disintegrins and Cell Migration

Cell migration is a key process for the defense of pluricellular organisms against pathogens, and it involves a set of surface receptors acting in an ordered fashion to contribute directionality to the movement. Among these receptors are the integrins, which connect the cell cytoskeleton to the extracellular matrix components, thus playing a central role in cell migration. Integrin clustering at focal adhesions drives actin polymerization along the cell leading edge, resulting in polarity of cell movement. Therefore, small integrin-binding proteins such as the snake venom disintegrins that inhibit integrin-mediated cell adhesion are expected to inhibit cell migration. Here we review the current knowledge on disintegrin and disintegrin-like protein effects on cell migration and their potential use as pharmacological tools in anti-inflammatory therapy as well as in inhibition of metastatic invasion

Heme and innate immunity: new insights for an old molecule

Hemolytic episodes such as sickle cell disease, malaria and ischemia-reperfusion occurrence are often associated to the statement of an inflammatory response which may develop or not to a chronic inflammatory status. Although these pathological states are triggered by distinct etiological agents, all of them are associated to high levels of free heme in circulation. In this review, we aim to focus the very recent achievements that have led to the statement of free heme as a proinflammatory molecule, which may play a central role during the onset and/or persistance of inflammation during these pathologies

High levels of filamentous actin and apoptosis correlate with mast cell refractoriness under alloxan-evoked diabetes

Submitted by Sandra Infurna ([email protected]) on 2019-12-31T18:02:17Z No. of bitstreams: 1 EmilianoBarreto_etal_IOC_2006.pdf: 458212 bytes, checksum: e9aae2b07e337f975cfe1755124fd360 (MD5)Approved for entry into archive by Sandra Infurna ([email protected]) on 2019-12-31T18:13:22Z (GMT) No. of bitstreams: 1 EmilianoBarreto_etal_IOC_2006.pdf: 458212 bytes, checksum: e9aae2b07e337f975cfe1755124fd360 (MD5)Made available in DSpace on 2019-12-31T18:13:22Z (GMT). No. of bitstreams: 1 EmilianoBarreto_etal_IOC_2006.pdf: 458212 bytes, checksum: e9aae2b07e337f975cfe1755124fd360 (MD5) Previous issue date: 2006Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Fisiologia e Farmacodinâmica. Laboratório de Inflamação. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Fisiologia e Farmacodinâmica. Laboratório de Inflamação. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Fisiologia e Farmacodinâmica. Laboratório de Inflamação. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Imunologia. Laboratório de Imunoparasitologia. Rio de Janeiro, RJ, Brasil.Universidade do Estado do Rio de Janeiro. Departamento de Farmacologia. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Fisiologia e Farmacodinâmica. Laboratório de Inflamação. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Fisiologia e Farmacodinâmica. Laboratório de Inflamação. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Fisiologia e Farmacodinâmica. Laboratório de Inflamação. Rio de Janeiro, RJ, Brasil.Mast cell number and reactivity were shown to be down-regulated under diabetic conditions. Since the balance between globular and filamentous actin plays a pivotal role in the activity of secretory cells, we investigated whether an imbalance in that system could underlie the hyporesponsiveness of mast cells in diabetes. The apoptotic state was also evaluated. By means of rhodamine/phalloidine staining of F-actin, we noted that diabetic mast cells exhibited an increase in fluorescence intensity and reduction in cellular size, when compared with cells from normal animals, in parallel with elevation in the percentage of cells developing apoptosis. The levels of Bax, a pro-apoptotic member of Bcl-2 family, appeared increased at baseline in mast cells from diabetic rats compared with normal cells. These phenomena correlated with reduction in histamine and PGD2 release following antigen challenge in vitro. The steroid antagonist RU 486 abolished the reduction of histamine secretion from diabetic mast cells. We conclude that hyporesponsiveness of mast cells noted in diabetes may be accounted for by reduction in actin filament plasticity, in clear association with the rise in the percentage of cells undergoing apoptosis. In addition, the refractoriness of diabetic mast cells to antigen in vitro seems to be dependent on glucocorticoids

Leukotriene B4 mediates neutrophil migration induced by heme

Submitted by Sandra Infurna ([email protected]) on 2017-11-01T16:38:21Z No. of bitstreams: 1 liliane_alves_etal_IOC_2011.pdf: 1162327 bytes, checksum: 89a12a98540b379ce9ab4d420ff18be5 (MD5)Approved for entry into archive by Sandra Infurna ([email protected]) on 2017-11-09T09:53:43Z (GMT) No. of bitstreams: 1 liliane_alves_etal_IOC_2011.pdf: 1162327 bytes, checksum: 89a12a98540b379ce9ab4d420ff18be5 (MD5)Made available in DSpace on 2017-11-09T09:53:44Z (GMT). No. of bitstreams: 1 liliane_alves_etal_IOC_2011.pdf: 1162327 bytes, checksum: 89a12a98540b379ce9ab4d420ff18be5 (MD5) Previous issue date: 2011Universidade Federal do Rio de Janeiro. Instituto de Biofísica Carlos Chagas Filho. Rio de Janeiro, RJ, Brasil.Universidade Federal do Rio de Janeiro. Instituto de Biofísica Carlos Chagas Filho. Rio de Janeiro, RJ, Brasil.Universidade Federal do Rio de Janeiro. Instituto de Biofísica Carlos Chagas Filho. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ. Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ. Brasil.Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de Góes. Departamento de Imunologia. Rio de Janeiro, RJ, Brasil.Universidade do Estado do Rio de Janeiro. Instituto de Biologia. Departamento de Farmacologia. Rio de Janeiro, RJ, Brasil.Universidade Federal do Rio de Janeiro. Instituto de Ciências Biomédicas. Rio de Janeiro, RJ, brasilUniversity of Michigan. Department of Internal Medicine, Division of Pulmonary and Critical care Medicine. Ann Arbor, MI, USA.Universidade Federal do Rio de Janeiro. Instituto de Biofísica Carlos Chagas Filho. Rio de Janeiro, RJ, Brasil.Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de Góes. Departamento de Imunologia. Rio de Janeiro, RJ, Brasil.Universidade Federal do Rio de Janeiro. Instituto de Biofísica Carlos Chagas Filho. Rio de Janeiro, RJ, Brasil.High concentrations of free heme found during hemolytic events or cell damage leads to inflammation, characterized by neutrophil recruitment and production of reactive oxygen species, through mechanisms not yet elucidated. In this study, we provide evidence that heme-induced neutrophilic inflammation depends on endogenous activity of the macrophage-derived lipid mediator leukotriene B(4) (LTB(4)). In vivo, heme-induced neutrophil recruitment into the peritoneal cavity of mice was attenuated by pretreatment with 5-lipoxygenase (5-LO) inhibitors and leukotriene B(4) receptor 1 (BLT1) receptor antagonists as well as in 5-LO knockout (5-LO(-/-)) mice. Heme administration in vivo increased peritoneal levels of LTB(4) prior to and during neutrophil recruitment. Evidence that LTB(4) was synthesized by resident macrophages, but not mast cells, included the following: 1) immuno-localization of heme-induced LTB(4) was compartmentalized exclusively within lipid bodies of resident macrophages; 2) an increase in the macrophage population enhanced heme-induced neutrophil migration; 3) depletion of resident mast cells did not affect heme-induced LTB(4) production or neutrophil influx; 4) increased levels of LTB(4) were found in heme-stimulated peritoneal cavities displaying increased macrophage numbers; and 5) in vitro, heme was able to activate directly macrophages to synthesize LTB(4). Our findings uncover a crucial role of LTB(4) in neutrophil migration induced by heme and suggest that beneficial therapeutic outcomes could be achieved by targeting the 5-LO pathway in the treatment of inflammation associated with hemolytic processes