Effects of a bradykinin B(2) receptor antagonist, FR173657, on pulmonary ischemia-reperfusion injury in dogs

Mechanistic insight on the role of leukotriene receptors in ischemic-reperfusion injury

Leukotrienes (LT) are a class of inflammatory mediators produced by the 5-lipoxygenase (5-LO) enzyme from arachidonic acid (AA). We discussed the various LT inhibitors and downstream pathway modulators, such as Mitogen-Activated Protein Kinases (MAPK), Phosphatidylinositol 3-Kinase/Protein Kinase B (PI3K/Akt), 5'-Adenosine Monophosphate-Activated Protein Kinase (AMPK), Protein Kinase C (PKC), Nitric Oxide (NO), Bradykinin, Early Growth Response-1 (Egr-1), Nuclear Factor-κB (NF-κB), and Tumor Necrosis Factor-Alpha (TNF-α), which in turn regulate various metabolic and physiological processes involving I/R injury. A systematic literature review of Bentham, Scopus, PubMed, Medline, and EMBASE (Elsevier) databases was carried out to understand the nature and mechanistic interventions of the leukotriene receptor modulations in ischemic injury. In the pathophysiology of I/R injuries, LT has been found to play an important role. I/R injury affects most of the vital organs and is characterized by inflammation, oxidative stress, cell death, and apoptosis leading to morbidity and mortality. sThis present review focuses on the various LT receptors, i.e., CysLT, LTC4, LTD4, and LTE4, involved in developing I/R injury in organs, such as the brain, spinal cord, heart, kidney, liver, and intestine.

Acute respiratory distress syndrome induction by pulmonary ischemia-reperfusion injury in large animal models

Acute respiratory distress syndrome (ARDS) is a common critical pulmonary complication after esophagectomy and other thoracic surgeries (e.g., lung transplantation, pulmonary thromboendarterectomy). Direct pulmonary ischemia-reperfusion injury (PIRI) is known to play the main role in induction of ARDS in these cases. Large animal models are an appropriate choice for ARDS as well as PIRI study because of their physiological and anatomic similarities to the human body. With regard to large animal models, we reviewed different methods of inducing in situ direct PIRI and the commonly applied methods for diagnosing and monitoring ARDS or PIRI in an experimental research setting.

The effects of exogenous interleukin-4 on hypoxia-induced lung injury

The aim of this study was to determine the effects of recombinant human interleukin-4 (rhIL-4) on hypoxia-induced lung injury in immature rats. The study was performed on 1-day-old Sprague Dawley rat pups. Group 1 (n = 7) served as nonhypoxic controls. Group 2 (untreated, n = 7) rats were subjected to hypoxia-reoxygenation (H/O) and were then returned to their mothers. Group 3 (rhIL-4 treated, n = 7) rats were subjected to H/O, were returned to their mothers, and were treated with rhIL-4 (75 microg/kg subcutaneously) for the next 3 days. All animals were killed on day 4 and lung specimens were obtained to determine the tissue level of malondialdehyde (MDA) and histological changes. In the untreated group, MDA levels were significantly increased compared to control and rhIL-4 groups. In the rhIL-4 treated group, MDA levels were not significantly different compared to control group. The rhIL-4 treated group had a significantly lower score of pathological lesions and alveolar hemorrhage grade values than the untreated group. The untreated animals had areas marked intraalveolar hemorrhage, capillary congestion, interstitial edema, and hypercellularity of lung that were not seen in the rhIL-4 treated rats. In conclusion, this study found beneficial effects of rhIL-4 in an experimental model on the hypoxia-induced lung injury.

Protective effects of recombinant human interleukin-4 administration on the hypoxia-reoxygenation-induced gastric and intestinal injury in rat pups

A total of 40 rat pups were randomly divided into 4 groups. Group 1 (sham) rats served as nonhypoxic controls. Group 2 (rhIL-4 treated/control) rats were administrated rIL-4 alone. Group 3 (hypoxia-reoxygenation [H-O]/untreated) rats were subjected to H-O and were then returned to their mothers. Group 4 (H-O/rhIL-4 treated) rats were subjected to H/O and were treated with rhIL-4 for the next 3 days. All animals were killed on day 4 and gastric and intestinal specimens were obtained to determine the tissue level of malondialdehyde (MDA) and histological changes. In group 3 MDA levels were significantly increased compared with groups 1,2, and 4. In group 4, MDA levels were not significantly different compared with group 3. The gastric and intestinal injury score were increased significantly in group 3 and 4 rats compared with group 1 and 2. However, this increase was lower in group 4 rats compared with group 3. In group 3, after hypoxia following reoxygenation, exfoliation and necrosis of superficial cells, blood cell infiltration, and structural alterations on the two-third parts of the glandular pits, and bleeding erosions developed in all stomachs. Treatment with rhIL-4 produced a reduction of exfoliation of superficial cells, hemorrhage, and blood cell infiltration. In group 3 animals, destruction of villi and crypts of ileum and in some cases extension to the muscularis were noticed. In contrast, in the rats treated with rhIL-4, lesions were limited essentially to the very tips of the villi. This study found beneficial effects of rhIL-4 in an experimental model of hypoxia-induced gastric and intestinal injury.

Bradykinin B2 receptor antagonist FR173657 ameliorates small bowel ischemia-reperfusion injury in dogs

Bradykinin mediates acute inflammation by increasing microvascular permeability, vasodilation, leukocyte migration and accumulation, and the production of arachidonic acid via phospholipase A2 activation. Arachidonic acid metabolites, or eicosanoids, are potent modulators of biological functions, particularly inflammation. Bradykinin exerts its inflammatory effects via the bradykinin B2 receptor. The aim of this study was to evaluate the effect of a bradykinin B2 receptor antagonist, FR173657 (FR), on intestinal ischemia-reperfusion (I/R) injury. Twenty-eight mongrel dogs were divided into four groups (n = 7 per group). Group I underwent I/R alone, Group II underwent I/R and received FR treatment, Group III was sham operated, and Group IV was sham operated and received FR treatment. The FR treatment consisted of FR continuously from 30 min prior to ischemia to 2 hr after reperfusion. In the I/R procedure, the superior mesenteric artery (SMA) and vein were clamped for 2 hr and then released to permit reperfusion for 12 hr. The intramucosal pH (pHi), SMA blood flow, and mucosal tissue blood flow were measured during the reperfusion period. The serum thromboxane B2 and 6-keto-prostaglandin F1alpha levels were determined, and tissue samples were examined histologically. Results showed that tissue blood flow, pHi, and SMA blood flow after reperfusion were maintained in Group II in comparison with Group I. Histopathological examination showed less severe mucosal damage after reperfusion in Group II than in Group I. The serum thromboxane B2 and 6-keto-prostagland in F1alpha levels were significantly lower in Group II than in Group I (P < 0.05). We conclude that FR treatment appears to have clear protective effects on small bowel I/R injury by inhibiting the release of eicosanoids.

Effects of a bradykinin B(2) receptor antagonist on ischemia-reperfusion injury in a canine lung transplantation model

BACKGROUND

This study investigated the effects of a bradykinin B(2) receptor antagonist, FR173657 (FR), on ischemia-reperfusion (I/R) injury in a canine lung transplantation model.

METHODS

Eighteen pairs of weight-matched dogs were randomly divided into 3 groups. Six pairs were assigned to the FR(D+R) group, in which FR (100 nmol/kg/h) was administered to the transplant donor continuously beginning 30 minutes before ischemia until the onset of ischemia, and FR was administered to the transplant recipient beginning 30 minutes before reperfusion and continuing for 2 hours after reperfusion. Another 6 pairs of dogs were assigned to the FR(R) group, in which FR was administered only to the recipient in the same manner as in the FR(D+R) group. The other pairs were assigned to the control group, in which vehicle alone was administered. Orthotopic left lung transplantation was performed after 12-hour cold storage in Euro-Collins solution. Fifteen minutes after reperfusion, the right pulmonary artery and the right stem bronchus were ligated. The animals were measured for 4 hours after reperfusion for left pulmonary vascular resistance (L-PVR), cardiac output (CO), arterial oxygen pressure (PaO(2)) and alveolar-arterial oxygen pressure difference (A-aD(O(2))). Lung specimens were harvested for measurement of the wet-to-dry lung weight ratio (WDR), histopathologic studies and polymorphonuclear neutrophil (PMN) count.

RESULTS

Compared with the control group, PaO(2), A-aDO(2), L-PVR and CO were all significantly (p < 0.05) improved and WDR significantly (p < 0.05) lower in both the FR(D+R) and FR(R) groups. Moreover, in the FR-treated groups, histologic tissue edema was mild, and PMN infiltration was significantly (p < 0.05) reduced.

CONCLUSIONS

The bradykinin B(2) receptor antagonist, FR173657, ameliorates I/R injury in lung grafts, indicating that protection of lung grafts can be achieved by the administration of FR solely to the transplant recipient.

Protection of lung tissue against ischemia/reperfusion injury by preconditioning with inhaled nitric oxide in an in situ pig model of normothermic pulmonary ischemia

Topical administration of nitric oxide (NO) by inhalation is currently used as therapy in various pulmonary diseases, but preconditioning with NO to ameliorate lung ischemia/reperfusion (I/R) injury has not been fully evaluated. In this study, we investigated the effects of NO inhalation on functional pulmonary parameters using an in situ porcine model of normothermic pulmonary ischemia. After left lateral thoracotomy, left lung ischemia was maintained for 90 min, followed by a 5h reperfusion period (group I, n = 7). In group II (n = 6), I/R was preceded by inhalation of NO (10 min, 15 ppm). Animals in group III (n = 7) underwent sham surgery without NO inhalation or ischemia. In order to evaluate the effects of NO preconditioning, lung functional and hemodynamic parameters were measured, and the zymosan-stimulated release of reactive oxygen species in arterial blood was determined. Animals in group I developed significant pulmonary I/R injury, including pulmonary hypertension, a decreased pO(2) level in pulmonary venous blood of the ischemic lung, and a significant increase of the stimulated release of reactive oxygen species. All these effects were prevented, or the onset (release of reactive oxygen species) was delayed, by NO inhalation. These results indicate that preconditioning by NO inhalation before lung ischemia is protective against I/R injury in the porcine lung.