RESUMO
The chemoattractant f-Met-Leu-Phe (FMLP) can modulate human coronary arterial tone without the involvement of peripheral leukocytes. We investigated the actions of FMLP and its cellular mechanism in human coronary arteries isolated 2-3 h after death. A single dose of FMLP (0.01-10 microM) produced transient contraction (or, followed by relaxation) responses in most human coronary rings examined. These responses to FMLP were in large part mediated by the generation of cyclooxygenase products, mainly thromboxane A2 (TXA2) and prostaglandin I2 (PGI2). Radiolabeled N-formyl hexapeptide. 125I-f-Nle-Leu-Phe-Nle-Tyr-Lys bound densely to intimal and adventitial sites that accumulated macrophages (CD68-positive) with a Kd of 14-29 nM and, further, weakly to the media with a Kd of 2.4-3.6 microM. Several cell types including macrophages, endothelial cells and smooth muscle cells were positively immunostained for both TXA2 synthase and PGI2 synthase. However, there was no significant relation between the magnitude of the responses to FMLP and dense macrophage accumulation in the intimal plaques or the adventitia. A reverse transcription-polymerase chain reaction showed predominant expression of FMLP receptor homologues, FPRH1 and FPRH2 mRNA, in human coronary medial tissues relative to that in leukocytes. In conclusion. FMLP produced transient tension changes in human coronary arteries, mainly via the generation of TXA2 and PGI2. This effect of FMLP did not appear to be mediated by the activation of densely accumulated intimal and/or adventitial macrophages, but by the activation of unidentified medial tissue cells which might have functional FMLP receptor homologues.
Assuntos
Vasos Coronários/efeitos dos fármacos , Oxirredutases Intramoleculares , Contração Isométrica/efeitos dos fármacos , N-Formilmetionina Leucil-Fenilalanina/farmacologia , Receptores Imunológicos/análise , Receptores de Peptídeos/análise , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Vasos Coronários/química , Vasos Coronários/fisiologia , Inibidores de Ciclo-Oxigenase/farmacologia , Sistema Enzimático do Citocromo P-450/análise , Endotélio Vascular/citologia , Inibidores Enzimáticos/farmacologia , Feminino , Humanos , Imidazóis/farmacologia , Indometacina/farmacologia , Isomerases/análise , Macrófagos , Masculino , Pessoa de Meia-Idade , Oligopeptídeos/metabolismo , Prostaglandinas/análise , RNA Mensageiro/análise , Receptores de Formil Peptídeo , Receptores Imunológicos/genética , Receptores de Peptídeos/genética , Tetra-Hidronaftalenos/farmacologia , Tromboxano A2/análogos & derivados , Tromboxano A2/análise , Tromboxano A2/antagonistas & inibidores , Tromboxano A2/farmacologia , Tromboxano-A Sintase/análise , Tromboxano-A Sintase/antagonistas & inibidoresRESUMO
Thromboxane synthase (TS) catalyzes the formation of thromboxane (TxA2) in monocytes/macrophages, platelets, and various tissues. TxA2 is likely to play a role in graft dysfunction due to its vasoconstrictive and platelet aggregatory properties. We studied the expression of TS in 7 normal native kidneys, 29 consecutive renal allograft biopsies (performed for rising serum creatinine, n = 23, and delayed graft function, n = 6), and one transplant nephrectomy specimen with severe acute rejection. TS expression was determined by immunocytochemistry using a monoclonal antibody against human TS, Kon-7. Histologic grading of the transplant biopsy specimens was based on the Banff classification. The degree of TS staining was graded in the glomeruli, interstitium, tubules and vessels from 0 to 3+. Of 29 biopsies, 13 had chronic nephropathy (CN), 6 had acute rejection (AR) with chronic nephropathy (AR/CN), 4 had acute rejection (AR), and 6 had acute tubular necrosis (ATN). TS staining of native kidneys showed sporadic interstitial cells. The biopsy and transplant nephrectomy specimens showed significant staining, predominantly in the glomeruli and interstitium. Positively staining cells appeared to be of macrophage/monocyte lineage by morphology. The mean glomerular staining grade was significantly increased in specimens with AR (2.3 +/- 0.9) and the mean interstitial staining was increased in specimens with AR/CN (2.2 +/- 0.9). Follow-up renal function 6 months post-biopsy showed that patients with higher TS staining grades had a faster decline in graft function. In conclusion, TS expression is increased in patients with acute rejection with or without chronic nephropathy and is associated with more rapid deterioration in function.
Assuntos
Rejeição de Enxerto/enzimologia , Transplante de Rim , Tromboxano-A Sintase/análise , Adulto , Biópsia , Feminino , Seguimentos , Rejeição de Enxerto/prevenção & controle , Humanos , Imunossupressores/uso terapêutico , Rim/enzimologia , Rim/patologia , Macrófagos/enzimologia , Macrófagos/patologia , Masculino , Pessoa de Meia-Idade , Transplante HomólogoRESUMO
Resident macrophages isolated from uninfected animals produce large quantities of arachidonic acid (AA) metabolites. Immunizing animals with protein antigens or bacteria activates macrophages and causes an 80% reduction in the cyclooxygenase and lipoxygenase metabolites relative to resident cells. Since some products have been shown to modulate immune functions, we examined how the AA metabolic enzyme activities regulate the products that are synthesized. We demonstrate that the cyclooxygenase, 5-lipoxygenase, prostacyclin synthase, and probably prostaglandin (PG) endoperoxide E-isomerase activities were decreased in activated peritoneal macrophages. In sharp contrast, thromboxane synthase activity was selectively unchanged or enhanced in the activated macrophages. Thus the immune response appears to modulate the activity of the AA and PG endoperoxide-dependent enzymes, thus dictating a major shift in the profile of metabolites synthesized by macrophages.