Involvement of formyl peptide receptors in the stimulatory effect of crotoxin on macrophages co-cultivated with tumour cells.

Crotoxin (CTX) is the main neurotoxic component of Crotalus durissus terrificus snake venom. It inhibits tumour growth and modulates the function of macrophages, which are essential cells in the tumour microenvironment. The present study investigated the effect of CTX on the secretory activity of monocultured macrophages and macrophages co-cultivated with LLC-WRC 256 cells. The effect of the macrophage secretory activities on tumour cell proliferation was also evaluated. Macrophages pre-treated with CTX (0.3 µg/mL) for 2 h were co-cultivated with LLC-WRC 256 cells, and the secretory activity of the macrophages was determined after 12, 24 and 48 h. The co-cultivation of CTX-treated macrophages with the tumour cells caused a 20% reduction in tumour cell proliferation. The production of both H2O2 and NO was increased by 41% and 29% after 24 or 48 h of co-cultivation, respectively, compared to the values for the co-cultures of macrophages of control. The level of secreted IL-1ß increased by 3.7- and 3.2-fold after 12 h and 24 h of co-cultivation, respectively. Moreover, an increased level of LXA4 (25%) was observed after 24 h of co-cultivation, and a 2.3- and 2.1-fold increased level of 15-epi-LXA4 was observed after 24 h and 48 h, respectively. Boc-2, a selective antagonist of formyl peptide receptors, blocked both the stimulatory effect of CTX on the macrophage secretory activity and the inhibitory effect of these cells on tumour cell proliferation. Taken together, these results indicate that CTX enhanced the secretory activity of macrophages, which may contribute to the antitumour activity of these cells, and that activation of formyl peptide receptors appears to play a major role in this effect.

Lung inflammation is induced by renal ischemia and reperfusion injury as part of the systemic inflammatory syndrome.

INTRODUCTION: Ischemia and reperfusion injury (IRI) are mainly caused by leukocyte activation, endothelial dysfunction and production of reactive oxygen species. Moreover, IRI can lead to a systemic response affecting distant organs, such as the lungs. AIM: The objective was to study the pulmonary inflammatory systemic response after renal IRI. METHODS: Male C57Bl/6 mice were subjected to 45 min of bilateral renal ischemia, followed by 4, 6, 12, 24 and 48 h of reperfusion. Blood was collected to measure serum creatinine and cytokine concentrations. Bronchoalveolar lavage fluid (BALF) was collected to determine the number of cells and PGE(2) concentration. Expressions of iNOS and COX-2 in lung were determined by Western blot. Gene analyses were quantified by real time PCR. RESULTS: Serum creatinine increased in the IRI group compared to sham mainly at 24 h after IRI (2.57 +/- 0.16 vs. 0.43 +/- 0.07, p < 0.01). The total number of cells in BAL fluid was higher in the IRI group in comparison with sham, 12 h (100 x 10(4) +/- 15.63 vs. 18.1 x 10(4) +/- 10.5, p < 0.05) 24 h (124 x 10(4) +/- 8.94 vs. 23.2 x 10(4) +/- 3.5, p < 0.05) and 48 h (79 x 10(4) +/- 15.72 vs. 22.2 x 10(4) +/- 4.2, p < 0.05), mainly by mononuclear cells and neutrophils. Pulmonary COX-2 and iNOS were up-regulated in the IRI group. TNF-alpha, IL-1beta, MCP-1, KC and IL-6 mRNA expression were up-regulated in kidney and lungs 24 h after renal IRI. ICAM-1 mRNA was up-regulated in lungs 24 h after renal IRI. Serum TNF-alpha, IL-1beta and MCP-1 and BALF PGE(2) concentrations were increased 24 h after renal IRI. CONCLUSION: Renal IRI induces an increase of cellular infiltration, up-regulation of COX-2, iNOS and ICAM-1, enhanced chemokine expression and a Th1 cytokine profile in lung demonstrating that the inflammatory response is indeed systemic, possibly leading to an amplification of renal injury.

Role of insulin on PGE2 generation during LPS-induced lung inflammation in rats.

Alterations in arachidonic acid (AA) metabolism have been reported to occur in diabetes mellitus. The present study was carried out to verify if these alterations are due to the relative lack of insulin or to high levels of blood glucose. Male Wistar rats were rendered diabetic by alloxan injection (42 mg/kg, i.v.), 10 or 30 days before the experiments. Some diabetic rats received a single dose (4 IU, s.c.) of NPH insulin 2 h before an intratracheal instillation of lipopolysaccharide (LPS, 750 microg) or saline. Six hours after LPS challenge, the following parameters were analysed: blood glucose levels, total and differential leukocyte counts in bronchoalveolar lavage (BAL) fluid; linoleic acid and AA content in blood neutrophils (HPLC), and levels of prostaglandin (PG)E(2) in BAL (ELISA). Relative to controls, a reduced number of neutrophils (18%) and decreased amounts of PGE(2) (40%) were observed in the BAL fluid of diabetic rats in response to LPS. A single dose of insulin was not able to reduce blood sugar levels to normal values, but instead resulted in the normalization of both leukocyte migration to the lungs and levels of PGE(2). Accordingly, these abnormalities might be primarily linked to a continuing insulin deficiency rather than to secondary hyperglycaemia occurring in the diabetic rat. In conclusion, data presented suggest that insulin might regulate neutrophil migration and generation of PGE(2) during the course of acute lung injury induced by LPS.

Lipoxygenase-derived eicosanoids are involved in the inhibitory effect of Crotalus durissus terrificus venom or crotoxin on rat macrophage phagocytosis.

Crotalus durissus terrificus snake venom and its major toxin, crotoxin or type II PLA2 subunit of this toxin, induce an inhibitory effect on spreading and phagocytosis in 2h incubated macrophages. The involvement of arachidonate-derived mediators on the inhibitory action of the venom or toxins on rat peritoneal macrophage phagocytosis was presently investigated. Peritoneal cells harvested from naive rats and incubated with the venom or toxins or harvested from the peritoneal cavity of rats pre-treated with the toxins were used. Zileuton, a 5-lipoxygenase inhibitor but not indomethacin, a cyclooxygenase inhibitor, given in vivo and in vitro abolished the inhibitory effect of venom or toxins on phagocytosis. Resident peritoneal macrophages incubated with the venom or toxins showed increased levels of prostaglandin E2 and lipoxin A4, with no change in leukotriene B4. These results suggest that lipoxygenase-derived eicosanoids are involved in the inhibitory effect of C.d. terrificus venom, crotoxin or PLA2 on macrophage phagocytosis.

Evidence that arachidonic acid derived from neutrophils and prostaglandin E2 are associated with the induction of acute lung inflammation by lipopolysaccharide of Escherichia coli.

OBJECTIVE: The involvement of arachidonic acid (AA) and PGE2 during the E. coli lipopolysaccharide (LPS)-induced acute lung injury was investigated. MATERIAL: Adult male Wistar rats were used. For in vitro studies, rat neutrophils, bronchoalveolar lavage (BAL) fluid, and lug vascular endothelium were used, as described below. TREATMENT: Rats were given an intratracheal injection of LPS (750 microg). METHODS: Total and differential cell counts in BAL fluid; enzyme-linked immunoassay (ELISA) analyses of TNF-alpha, IL-1beta, LTB4 and PGE2 in BAL, and immunohistochemical detection of ICAM-1 on lung vascular endothelium were performed six h after LPS challenge. Fatty acid composition of blood neutrophils and plasma was analyzed by HPLC. RESULTS: Rats instilled with LPS presented a sixty three-fold increase in the number of neutrophils in BAL (from 0.5 x 10(6) to 31.5 x 10(6) cells), accompanied by increased levels of TNF-alpha and IL-1beta (p < 0.001), and a three-fold increase in ICAM-1 expression on vascular endothelium. The content of AA in blood neutrophils was reduced by 50%, whereas the level of PGE2 in BAL was increased by 3.5 fold, without changes in the levels of LTB4. CONCLUSIONS: These findings suggest that AA and PGE2 are associated with LPS challenge.