Many in vitro studies have used cell cultures to focus on the relationships between cyclo-oxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) isoforms. We have investigated the time-course of regulation and the role of COX-2 and iNOS in a model of experimental inflammation in mice, the air pouch injected with zymosan. This study demonstrates that there is an early acute phase (4 h) mediated mainly by eicosanoids, with high levels of prostaglandin E2 (PGE2) produced by cyclo-oxygenase-1. In addition, in the later phase (from 12 h) there is a participation of nitric oxide (NO) and PGE2 accompanied by co-induction of both iNOS and COX-2. These enzymes were detected in migrating leukocytes as well as in macrophages lining the air pouch. Administration of NS398 or indomethacin inhibited PGE2 levels and COX activity, but also nitrite levels and iNOS activity, which was accompanied by a reduction in iNOS expression. Aminoguanidine inhibited nitrite levels and iNOS activity in addition to exerting inhibitory effects on the COX pathway. Treatment of animals with dexamethasone reduced nitrite and PGE2 concentrations in air pouch exudates, as well as iNOS and COX-2 expression in migrating cells. Our results indicate that PGE2 and NO may play in vivo mutual modulatory roles in the inflammatory response caused by zymosan injection into the mouse air pouch, a suitable model to study drugs acting on those pathways.

Chemokines are a family of small polypeptides which specialize in the attraction of leukocytes. The presence of specific leukocyte subsets at the implantation site is an important element of the complex, and not completely understood, process of embryonic implantation. This report includes the investigation of the in-vivo immunolocalization and hormonal regulation of interleukin (IL)-8, monocyte chemotactic protein (MCP)-1 and RANTES (regulated upon activation normal T-cell expressed and secreted) in the human endometrium during hormone replacement therapy cycles for oocyte recipients in an IVF programme. In addition, we have analysed the embryonic regulation of these endometrial epithelial chemokines (IL-8 and MCP-1) using an in-vitro model for the apposition phase of human implantation by co-culturing single human embryos until the blastocyst stage with human endometrial epithelial cells (EEC). IL-8 and MCP-1 were immunolocalized in the human endometrium to the glandular and lumenal epithelium as well as to the endothelial cells. RANTES was mainly localized to the stromal compartment and endothelial cells. The immunoreactive levels of endometrial IL-8 and MCP-1 were up-regulated by the administration of progesterone during the receptive phase of the cycle. Furthermore, it was demonstrated that, in vitro, the human blastocyst does not produce measurable amounts of IL-8, MCP-1 or RANTES; however, it does up-regulate EEC IL-8 mRNA expression (P < 0.05) and protein production (P < 0.05), but not IL-8 secretion. The human embryo did not regulate EEC MCP-1 expression. These results provide evidence of hormonal and embryonic regulation of specific endometrial chemokines, suggesting two different but related mechanisms to induce the production of chemokines by the EEC, thus contributing to the attraction of specific leukocyte populations during the peri-implantation phase.

We have isolated several cDNA's complementary to gamma-glutamyltranspeptidase (GGT) mRNA by screening a rat kidney library constructed in lambda gtll with antibodies specifically reactive to the enzyme protein. The clone selected an mRNA that was translated into a 62 Kd peptide, corresponding to the GGT precursor. The longest clone isolated was 1842 bp long with an open reading frame coding for 565 amino acids. The length of the mRNA coding for GGT was estimated to be 2.2 kb long. The amino acid sequence derived from the nucleotide sequence matched the short sequences determined by us as well as by other authors.

1 We have studied the participation of nitric oxide (NO) in an animal model of in¯ammation, the rat air pouch stimulated with zymosan. 2 Saline or zymosan was injected into 6-day rat air pouches at dierent time points and measurements were made of cell migration, levels of nitrite/nitrate (NO 2 7 /NO 3 7 ), prostaglandin E 2 (PGE 2 ), leukotriene B 4 (LTB 4 ) and secretory phospholipase A 2 (sPLA 2 ) in exudates. Nitric oxide synthase (NOS) activity was determined in high speed supernatants from cells present in pouch exudates. Western blot analysis was also performed on these samples. 3 Zymosan injection induced a time-dependent increase in leukocyte in®ltration, NO 2 7 /NO 3 7 levels and cellular NOS activity that reached a peak by 8 h. Western blot analysis showed the same time course for induction of NOS protein. Colchicine administration to rats inhibited cellular in®ltration and decreased the levels of NO metabolites and cellular NOS activity zymosan-injected air pouch at 8 h. NOS activity was present in polymorphonuclear leukocytes (PMNs) and monocytes, but not in the lymphocytes present in exudates. This enzyme is calcium-independent and needs NADPH for activity. PGE 2 levels in exudates showed a time course inverse to that of NOS activity and NO metabolites, with maximum levels of PGE 2 observed at 4 h after zymosan injection. 4 Administration of N G -nitro-L-arginine methyl ester (L-NAME) or aminoguanidine to rats signi®-cantly reduced cellular NOS activity, NO 2 7 /NO 3 7 levels and chemiluminescence, whereas they were without eect on cell migration and degranulation, eicosanoid levels and sPLA 2 activity. 5 Treatment of animals with dexamethasone inhibited cellular NOS activity, NO 2 7 /NO 3 7 levels, chemiluminescence and the increase in the levels of PGE 2 and LTB 4 , with only a weak eect on elastase release. 6 Administration of the selective cyclo-oxygenase-2 (COX-2) inhibitor NS398 to rats strongly reduced PGE 2 levels in exudates without aecting NO metabolites or NOS activity at 4 h after zymosan injection. 7 Our data indicate that NOS is induced in the zymosan-stimulated rat air pouch model of in¯ammation. This enzyme is expressed in the cells migrating into the air pouch and caused an increased production of NO metabolites in exudates. The results also suggest the presence of an earlier phase in which eicosanoids play the main role, with participation of COX-2 activity, and a later phase mediated by NO. The endogenous release of NO does not modify prostaglandin biosynthesis in this in vivo model.

No abstract