Plasma cytokine expression after lower-limb compression in rats.

OBJECTIVES: Muscle injury due to crushing (muscle compression injury) is associated with systemic manifestations known as crush syndrome. A systemic inflammatory reaction may also be triggered by isolated muscle injury. The aim of this study was to investigate the plasma levels of interleukins (IL) 1, 6 and 10 and tumor necrosis factor alpha (TNF-α), which are markers for possible systemic inflammatory reactions, after isolated muscle injury resulting from lower-limb compression in rats. METHODS: Male Wistar rats were subjected to 1 h of compression of their lower limbs by means of a rubber band. The plasma levels of IL 1, 6 and 10 and TNF-α were measured 1, 2 and 4 h after the rats were released from compression. RESULTS: The plasma levels of IL 10 decreased in relation to those of the other groups, with a statistically significant difference (p < 0.05). The method used did not detect the presence of IL 1, IL 6 or TNF-α. CONCLUSION: Our results demonstrated that the changes in plasma levels of IL 10 that were found may have been a sign of the presence of circulating interleukins in this model of lower-limb compression in rats.

OBJETIVOS: A lesão muscular por esmagamento (lesão por compressão muscular) está associada a manifestações sistêmicas conhecidas como síndrome do esmagamento. A reação inflamatória sistêmica pode também ser desencadeada pela lesão muscular isolada. O objetivo deste estudo foi investigar os níveis plasmáticos de interleucinas (IL) 1, 6, 10 e TNF-α, marcadores de uma possível reação inflamatória sistêmica, após a lesão muscular isolada resultante da compressão de membros inferiores de ratos. MÉTODOS: Ratos Wistar machos foram submetidos a uma hora de compressão dos membros inferiores por uma faixa de borracha. Os níveis plasmáticos de IL 1, 6, 10 e TNF-α foram medidos uma, duas e quatro horas após a liberação da compressão. RESULTADOS: Os níveis plasmáticos de IL 10 diminuíram quando comparados com outros grupos com diferença estatisticamente significante (p < 0,05). Não houve detecção, pelo método, da presença de IL 1, 6 e TNF-α. CONCLUSÃO: Nossos resultados demonstraram que as alterações dos níveis plasmáticos de IL 10 encontradas podem ser um sinal da presença de interleucinas circulantes nesse modelo de compressão de membros inferiores de ratos.

Plasma cytokine expression after lower-limb compression in rats / Expressão de citoquinas plasmáticas após compressão de membros inferiores de ratos

Muscle injury due to crushing (muscle compression injury) is associated with systemic manifestations known as crush syndrome. A systemic inflammatory reaction may also be triggered by isolated muscle injury. The aim of this study was to investigate the plasma levels of interleukins (IL) 1, 6 and 10 and tumor necrosis factor alpha (TNF-α), which are markers for possible systemic inflammatory reactions, after isolated muscle injury resulting from lower-limb compression in rats. METHODS: Male Wistar rats were subjected to 1 h of compression of their lower limbs by means of a rubber band. The plasma levels of IL 1, 6 and 10 and TNF-α were measured 1, 2 and 4 h after the rats were released from compression. RESULTS: The plasma levels of IL 10 decreased in relation to those of the other groups, with a statistically significant difference (p < 0.05). The method used did not detect the presence of IL 1, IL 6 or TNF-α. CONCLUSION: Our results demonstrated that the changes in plasma levels of IL 10 that were found may have been a sign of the presence of circulating interleukins in this model of lower-limb compression in rats...

A lesão muscular por esmagamento (lesão por compressão muscular) está associada a manifestações sistêmicas conhecidas como síndrome do esmagamento. A reação inflamatória sistêmica pode também ser desencadeada pela lesão muscular isolada. O objetivo deste estudo foi investigar os níveis plasmáticos de interleucinas (IL) 1, 6, 10 e TNF-α, marcadores de uma possível reação inflamatória sistêmica, após a lesão muscular isolada resultante da compressão de membros inferiores de ratos. MÉTODOS: ratos Wistar machos foram submetidos a uma hora de compressão dos membros inferiores por uma faixa de borracha. Os níveis plasmáticos de IL 1, 6, 10 e TNF-α foram medidos uma, duas e quatro horas após a liberação da compressão. RESULTADOS: os níveis plasmáticos de IL 10 diminuíram quando comparados com outros grupos com diferença estatisticamente significante (p < 0,05). Não houve detecção, pelo método, da presença de IL 1, 6 e TNF-α. CONCLUSÃO: nossos resultados demonstraram que as alterações dos níveis plasmáticos de IL 10 encontradas podem ser um sinal da presença de interleucinas circulantes nesse modelo de compressão de membros inferiores de ratos...

Leukocyte infiltration in lung, muscle, and liver after limb compression in rats.

Muscle crush injury is associated with systemic manifestations known as crush syndrome. A systemic inflammatory response syndrome may be triggered by isolated crush injury. Using myeloperoxidase (MPO) activity and plasma fatty acid composition, we investigated the inflammatory response in distant organs after isolated limb compression in rats. Male Wistar rats were submitted to 1h of hind limb compression by a latex ribbon. Myeloperoxidase activity was measured in muscle, liver, and lung at progressive times (1, 2 or 4h) after bandage release. Plasma fatty acid composition was evaluated as an indirect measure of oxidative stress. The liver and hind limb muscles showed a transient increase in MPO activity. Pulmonary MPO activity, otherwise, increased progressively throughout the study and reached statistically significant values at 4h when compared to all other groups (p<0.05). Plasma levels of unsaturated fatty acids decreased gradually after decompression (p<0.05 compared to controls after 4h). Blunt traumatic muscle compression was associated with rapid and transient muscle and liver inflammatory cell infiltration but otherwise, polymorphonuclear cells showed progressive aggregation in lungs. The plasmatic unsaturated index decreased throughout the 4h after muscle release. We demonstrated that limb compression was associated with oxidative stress and distant inflammatory responses. Progressive inflammatory cell infiltration in lungs could be related with the delayed systemic adverse responses found after crush injury.

Lonomia obliqua (Lepidoptera, Saturniidae) caterpillar bristle extract induces direct lysis by cleaving erythrocyte membrane glycoproteins.

Lonomia obliqua caterpillar bristle extract induces hemolysis in vitro on washed human and rat erythrocytes, in either the absence or presence of exogenous lecithin. In the former condition, phospholipases A(2) are key enzymes involved in hemolysis. However, the mechanism whereby this extract causes direct hemolysis is not known. Thus, the aim of this study was to investigate the hemolytic mechanism of the crude extract of the caterpillar L. obliqua on human erythrocytes in the absence of lecithin. The extract significantly increased the erythrocyte osmotic fragility and promoted the removal of glycophorins A and C, and band 3 from the erythrocyte membrane. The use of Ca2+ and Mg2+ ions significantly potentiated glycoprotein removal, remarkably of erythrocyte band 3. The composition of fatty acids was analyzed by HPLC in both L. obliqua caterpillar bristle extract and human erythrocyte membranes incubated with the extract. The levels of unsaturated fatty acids were remarkably augmented in erythrocytes incubated with the extract than in control erythrocytes, modifying thereby the saturated/unsaturated fatty acid ratio. Altogether, evidence is provided here that the interplay of at least three mechanisms of action accounts for the direct activity of the bristle extract on erythrocyte membrane, leading to hemolysis: the removal of glycoproteins and band 3; the insertion of fatty acids; and the action of phospholipases. Such mechanisms might affect erythrocyte flexibility and deformability, which may induce hemolysis by increasing erythrocyte fragility. However, whether the direct hemolytic activity of L. obliqua caterpillar is the major cause of intravascular hemolysis during envenomation still needs further investigation.

Neutrophil death induced by a triathlon competition in elite athletes.

INTRODUCTION/PURPOSE: The effect of a triathlon competition on death of neutrophils from elite athletes was investigated. METHODS: Blood was collected from 11 sedentary volunteers and 12 triathletes under rest and after a Half Ironman triathlon competition (2-km swimming, 80-km cycling, and 20-km running). RESULTS: The triathlon competition increased DNA fragmentation, phosphatidylserine externalization, and reactive oxygen species production in neutrophils when compared to the results at rest. The proportion of neutrophils with mitochondrial transmembrane depolarization was increased in the triathletes at rest and after competition as compared with sedentary volunteers. Plasma levels of thiobarbituric acid reactive substances were increased in triathletes after competition. Expression of bcl-xL (antiapoptotic) was decreased and that of bax (proapoptotic) was increased, whereas intracellular neutral lipid content was lowered in neutrophils after the triathlon. A positive correlation was found between the proportion of neutrophils with DNA fragmentation and the plasma free fatty acid levels (r = 0.688, P< 0.05), which was elevated by threefold after competition. Plasma levels of oleic, linoleic, and stearic acids were increased in triathletes after the competition when compared with sedentary volunteers. The plasma concentration of these three fatty acids, measured after the triathlon competition, was toxic for 3-h cultured neutrophils obtained from sedentary volunteers. The maximal tolerable (nontoxic) concentration of the fatty acids by 3-h cultured neutrophils was 100 micromol x L(-1) for oleic and linoleic acids and 200 micromol x L(-1) for stearic acid. CONCLUSION: The triathlon competition induced neutrophil death possibly by apoptosis as indicated by DNA fragmentation and phosphatidylserine externalization. The increase in plasma levels of oleic, linoleic, and stearic acids induced by the competition may be involved in the neutrophil death observed possibly by increasing the production of reactive oxygen species and by decreasing the accumulation of intracellular neutral lipid.

Effect of docosahexaenoic acid-rich fish oil supplementation on human leukocyte function.

BACKGROUND: The effect of a docosahexaenoic acid (DHA)-rich fish oil (FO) supplementation on human leukocyte function was investigated. METHODS: Ten male volunteers were supplemented with 3g/day FO containing 26% eicosapentaenoic acid (EPA, 20:5, n-3) and 54% DHA (22:6, n-3) for 2 months. RESULTS: FO supplementation changed the fatty acid (FA) composition of leukocytes resulting in an increase of n-3/n-6 ratio from 0.18 to 0.62 in lymphocytes and from 0.15 to 0.70 in neutrophils. DHA-rich FO stimulated an increase in phagocytic activity by 62% and 145% in neutrophils and monocytes, respectively. Neutrophil chemotactic response was increased by 128%. The rate of production of reactive oxygen species by neutrophils was also increased, as it was with lymphocyte proliferation. These changes were partially reversed after a 2-month wash out period. With respect to cytokine production by lymphocytes, interleukin (IL)-4 release was not altered, whereas secretions of IL-10, interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha were raised. These results are in contrast to those described by others using EPA-rich FO supplementation. Lymphocyte pleiotropic gene expression was analyzed by a macroarray technique. Of the analyzed genes (588 in total), 77 were modified by the supplementation. FO supplementation resulted in up-regulation of 6 genes (GATA binding protein 2, IL-6 signal transducer, transforming growth factor alpha, TNF, heat shock 90kDa protein 1-alpha and heat shock protein 70kDa 1A) and a down regulation of 71 genes (92.2% of total genes changed). The largest functional group of altered genes was that related to signaling pathways (22% of the total modified genes). CONCLUSIONS: Therefore, although EPA and DHA are members of n-3 FA family, changes in the proportion of DHA and EPA exert different effects on neutrophil, monocyte and lymphocyte function, which may be a result of specific changes in gene expression.

Toxicity of a soybean oil emulsion on human lymphocytes and neutrophils.

BACKGROUND: The incorporation of lipid emulsions in parenteral diets is a requirement for energy and essential fatty acid supply to critically ill patients. In this study, the toxicity of a lipid emulsion rich (60%) in triacylglycerol of omega-6 polyunsaturated fatty acids on leukocytes from healthy volunteers was investigated. METHODS: Eleven volunteers were recruited, and blood samples were collected before infusion of a soybean oil emulsion, immediately afterwards, and 18 hours later. The cells were studied immediately after isolation and again after 24 hours or 48 hours in culture. The following determinations were made: composition and concentration of fatty acids in plasma, lymphocytes and neutrophils, lymphocyte proliferation, levels of cell viability, DNA fragmentation, phosphatidylserine externalization, mitochondrial depolarization, reactive oxygen species production, and neutral lipid accumulation. RESULTS: Soybean oil emulsion decreased lymphocyte proliferation and provoked neutrophil and lymphocyte apoptosis and necrosis. Evidence is presented herein that soybean oil emulsion is less toxic to neutrophils than to lymphocytes. The mechanism of cell death induced by this oil emulsion was characterized by mitochondrial membrane depolarization and neutral lipid accumulation but did not alter reactive oxygen species production. CONCLUSIONS: Soybean oil emulsion given as a single dose of 500 mL promotes lymphocyte and neutrophil death that may enhance the susceptibility of the patients to infections.

Modulation of lymphocyte proliferation by macrophages and macrophages loaded with arachidonic acid.

Arachidonic acid (AA) is incorporated and exported by macrophages. This fatty acid is also transferred from macrophages (Mphi) to lymphocytes (LY) in co-culture. This observation led us to investigate the effect of macrophages pre-loaded with AA on concanavalin A (Con A)-stimulated lymphocyte proliferation. The experiments were performed in co-culture. This condition reproduces the in vivo microenvironment in which the modulation of lymphocyte proliferation is dependent on the interaction with macrophages. Lymphocytes obtained from untreated rats or from intraperitoneally thioglycolate-injected rats (THIO-treated) were co-cultured with macrophages from the same rats. Firstly, macrophages were co-cultured for 48 h with Con A-stimulated lymphocytes in different proportions: 0.5, 1, 2.5, 5, 10, 20 and 30% of 5 x 10(5) lymphocytes per well. At 1% proportion, macrophages caused maximum stimulation of lymphocyte proliferation; a four- to five-fold increase, for cells from both thioglycolate-treated and untreated rats, respectively, whereas at 20% it caused maximum inhibition. In addition, 1 or 20% macrophages were pre-loaded with several AA concentrations during a period of 6 h and co-cultured with lymphocytes. At 180 microM AA and 1% macrophages, lymphocyte proliferation was inhibited (by 25%), whereas at 20% macrophages, proliferation was increased, by 25- and three-fold, respectively, for cells from untreated and THIO-treated rats. AA added directly to the medium reduced lymphocyte proliferation, also being toxic to these cells at 100 microM. No toxic effects of AA were observed on macrophages. Additional evidence suggests that nitric oxide production is involved in the modulation of lymphocyte proliferation by AA-pre-loaded macrophages. These findings support the proposition that AA can directly modulate lymphocyte proliferation and the interaction between macrophages and lymphocytes.

Uma fonte adicional de ácidos graxos para o músculo esquelético: os leucócitos / An additional source of fatty acids to skeletal muscle: the leukocytes

No exercício físico, há aumento na demanda energéticapela musculatura esquelética.Para suprir esta demanda, dois substratos säo importantes: a glicose e os ácidos graxos(AG).