Anti-rat IL-8 (CINC) monoclonal antibody administration reduces ischemia-reperfusion injury in small intestine

Effect of haemodynamic changes on epithelium-related intestinal injury in off-pump coronary surgery

OBJECTIVES

Intestinal injury is thought to play a central role in the occurrence of multiorgan dysfunction after on-pump coronary surgery. Clinical benefits of off-pump revascularisation remain, however, controversial.

MATERIAL AND METHODS

Hepatic enzymes and plasmatic IL-6, IL-8 and intestinal-type fatty acid binding protein (I-FABP) were determined in 20 patients (age 65-75) undergoing either on-pump (n = 10) or off-pump (n = 10) coronary surgery. Haemodynamic and biochemical parameters, catecholamine and volume therapy were monitored.

RESULTS

Central venous pressure (CVP) was significantly higher in the off-pump group during and 12h after operation (9.5 ± 1.35 vs. 6.21 ± 0.63 mmH2O, p = 0.012). Higher GGT and GLDH levels occurred in the off-pump group and correlated with the elevated I-FABP levels at 24h (935.8 ± 83.7 vs. 370.4 ± 67.7 pg/mL, p<0.001). CVP correlated with I-FABP peak values (Pearson's coefficient 0.852). IL-6 and IL-8 were released to a lower extent in the off-pump group compared to on pump (p<0.05) at 24h (139.3 ± 27.7 vs. 279.4 ± 56.2 and 15.3 ± 7.4 vs. 38.5 ± 13.8 pg/mL) and at 72 h post-operatively (4.5 ± 2.1 vs. 30.1 ± 12.1 and 7.8 ± 1.2 vs. 17.1 ± 5.2 pg/mL).

CONCLUSIONS

While inflammatory activation is reduced with CPB avoidance, elevated CVP during off-pump surgery is followed by temporary postoperative enterocyte damage that may threaten the normal function of the gastrointestinal system and lead - in certain groups of high risk patients--to irrecoverable injury.

Neutrophil priming by hypoxic preconditioning protects against epithelial barrier damage and enteric bacterial translocation in intestinal ischemia/reperfusion

Intestinal ischemia/reperfusion (I/R) induces mucosal barrier dysfunction and bacterial translocation (BT). Neutrophil-derived oxidative free radicals have been incriminated in the pathogenesis of ischemic injury in various organs, but their role in the bacteria-containing intestinal tract is debatable. Primed neutrophils are characterized by a faster and higher respiratory burst activity associated with more robust bactericidal effects on exposure to a second stimulus. Hypoxic preconditioning (HPC) attenuates ischemic injury in brain, heart, lung and kidney; no reports were found in the gut. Our aim is to investigate whether neutrophil priming by HPC protects against intestinal I/R-induced barrier damage and bacterial influx. Rats were raised in normoxia (NM) or kept in a hypobaric hypoxic chamber (380 Torr) 17 h/day for 3 weeks for HPC, followed by sham operation or intestinal I/R. Gut permeability was determined by using an ex vivo macromolecular flux assay and an in vivo magnetic resonance imaging-based method. Liver and spleen homogenates were plated for bacterial culturing. Rats raised in HPC showed diminished levels of BT, and partially improved mucosal histopathology and epithelial barrier function compared with the NM groups after intestinal I/R. Augmented cytokine-induced neutrophil chemoattractant (CINC)-1 and -3 levels and myeloperoxidase activity correlated with enhanced infiltration of neutrophils in intestines of HPC-I/R compared with NM-I/R rats. HPC alone caused blood neutrophil priming, as shown by elevated production of superoxide and hydrogen peroxide on stimulation, increased membrane translocation of cytosolic p47(phox) and p67(phox), as well as augmented bacterial-killing and phagocytotic activities. Neutrophil depletion reversed the mucosal protection by HPC, and aggravated intestinal leakiness and BT following I/R. In conclusion, neutrophil priming by HPC protects against I/R-induced BT via direct antimicrobial activity by oxidative respiratory bursts and through promotion of epithelial barrier integrity for luminal confinement of enteric bacteria.

Receptor binding mode and pharmacological characterization of a potent and selective dual CXCR1/CXCR2 non-competitive allosteric inhibitor

BACKGROUND AND PURPOSE

DF 2156A is a new dual inhibitor of IL-8 receptors CXCR1 and CXCR2 with an optimal pharmacokinetic profile. We characterized its binding mode, molecular mechanism of action and selectivity, and evaluated its therapeutic potential.

EXPERIMENTAL APPROACH

The binding mode, molecular mechanism of action and selectivity were investigated using chemotaxis of L1.2 transfectants and human leucocytes, in addition to radioligand and [(35) S]-GTPγS binding approaches. The therapeutic potential of DF 2156A was evaluated in acute (liver ischaemia and reperfusion) and chronic (sponge-induced angiogenesis) experimental models of inflammation.

KEY RESULTS

A network of polar interactions stabilized by a direct ionic bond between DF 2156A and Lys(99) on CXCR1 and the non-conserved residue Asp(293) on CXCR2 are the key determinants of DF 2156A binding. DF 2156A acted as a non-competitive allosteric inhibitor blocking the signal transduction leading to chemotaxis without altering the binding affinity of natural ligands. DF 2156A effectively and selectively inhibited CXCR1/CXCR2-mediated chemotaxis of L1.2 transfectants and leucocytes. In a murine model of sponge-induced angiogenesis, DF 2156A reduced leucocyte influx, TNF-α production and neovessel formation. In vitro, DF 2156A prevented proliferation, migration and capillary-like organization of HUVECs in response to human IL-8. In a rat model of liver ischaemia and reperfusion (I/R) injury, DF 2156A decreased PMN and monocyte-macrophage infiltration and associated hepatocellular injury.

CONCLUSION AND IMPLICATIONS

DF 2156A is a non-competitive allosteric inhibitor of both IL-8 receptors CXCR1 and CXCR2. It prevented experimental angiogenesis and hepatic I/R injury in vivo and, therefore, has therapeutic potential for acute and chronic inflammatory diseases.

Pulmonary gas exchange impairment following tourniquet deflation: a prospective, single-blind clinical trial

The tourniquet has been considered as a recognized cause of limb ischemia/reperfusion injury in orthopedic surgery resulting in a transient neutrophil, monocyte activation, and enhanced neutrophil transendothelial migration with potential remote tissue injury. This study investigated the effect of unilateral tourniquet application within a safe time limit on pulmonary function and the roles of lipid peroxidation and systemic inflammatory response. Thirty patients undergoing unilateral lower extremity surgery with or without tourniquet were equally divided into a control group with no tourniquet (Group C) and a tourniquet (Group T). Arterial partial pressure of oxygen (P(a)O(2)), arterial-alveolar oxygen tension ratio (a/A ratio), alveolar-arterial oxygen difference (A-aDO(2)) and respiratory index, plasma malondialdehyde, serum interleukin (IL) -6 and IL-8 levels were measured immediately before and 1 hour after tourniquet inflation/operation beginning, 0.5, 2, 6, and 24 hours after tourniquet deflation/operation ending. The results represented no significant changes in Group C with regard to either blood gas variables or levels of circulating mediators, while blood gas variable changes of greater A-aDO(2) and respiratory index and lower PaO2 and a/A ratio were shown at 6 hours following tourniquet deflation. The levels of malondialdehyde, IL-6, and IL-8 were increased over baseline values from 2 to 24 hours following tourniquet deflation in Group T. We concluded that tourniquet application within a safe time limit may cause pulmonary gas exchange impairment several hours after tourniquet deflation, where lipid peroxidation and systemic inflammatory response may be involved.

Enterocyte shedding and epithelial lining repair following ischemia of the human small intestine attenuate inflammation

Background

Recently, we observed that small-intestinal ischemia and reperfusion was found to entail a rapid loss of apoptotic and necrotic cells. This study was conducted to investigate whether the observed shedding of ischemically damaged epithelial cells affects IR induced inflammation in the human small gut.

Methods and Findings

Using a newly developed IR model of the human small intestine, the inflammatory response was studied on cellular, protein and mRNA level. Thirty patients were consecutively included. Part of the jejunum was subjected to 30 minutes of ischemia and variable reperfusion periods (mean reperfusion time 120 (±11) minutes). Ethical approval and informed consent were obtained. Increased plasma intestinal fatty acid binding protein (I-FABP) levels indicated loss in epithelial cell integrity in response to ischemia and reperfusion (p<0.001 vs healthy). HIF-1α gene expression doubled (p = 0.02) and C3 gene expression increased 4-fold (p = 0.01) over the course of IR. Gut barrier failure, assessed as LPS concentration in small bowel venous effluent blood, was not observed (p = 0.18). Additionally, mRNA expression of HO-1, IL-6, IL-8 did not alter. No increased expression of endothelial adhesion molecules, TNFα release, increased numbers of inflammatory cells (p = 0.71) or complement activation, assessed as activated C3 (p = 0.14), were detected in the reperfused tissue.

Conclusions

In the human small intestine, thirty minutes of ischemia followed by up to 4 hours of reperfusion, does not seem to lead to an explicit inflammatory response. This may be explained by a unique mechanism of shedding of damaged enterocytes, reported for the first time by our group.

Mast cells are involved in the pathogenesis of indomethacin-induced rat enteritis

BACKGROUND

Nonsteroidal antiinflammatory drug (NSAID)-induced enteropathy is clinically very important, but the pathological mechanisms remain unclear. Mast cells have been reported to play an important role in the pathogenesis of indomethacin-induced small intestinal injury. In this study, we investigated the role of mast cells in indomethacin-induced small intestinal injury using mast cell deficiency (Ws/Ws) rat.

METHODS

Ws/Ws rats and control (W+/W+) rats were given indomethacin (15 mg/kg) subcutaneously, and the intestinal mucosal damage was estimated after 24 h.

RESULTS

The area (mm2) of macroscopic visible lesions, the concentrations of thiobarbituric acid-reactive substances (TBARS) as an index of lipid peroxidation, myeloperoxidase (MPO) activity as an index of neutrophil accumulation, and the content of cytokine-induced neutrophil chemoattractant-1 (CINC-1) were significantly increased in indomethacin-treated groups compared with the sham groups. The development of intestinal lesions in response to indomethacin was prevented in Ws/Ws rats compared with W+/W+ rats, together with significant suppression of the increased levels of TBARS, MPO activities, and CINC-1 levels.

CONCLUSIONS

These results indicate that mast cells are involved in the pathogenesis of the intestinal mucosal damage induced by indomethacin.

CV-11974, angiotensin II type I receptor antagonist, reduces the severity of indomethacin-induced rat enteritis

The aim of the present study was to examine the effect of angiotensin II type I receptor antagonist, CV-11974, on indomethacin-induced small intestinal injury in rats. Single administration of indomethacin provoked severe inflammatory lesions in the small intestine. The levels of thiobarbituric acid-reactive substances (TBARS), myeloperoxidase (MPO) activities and cytokine-induced neutrophil chemoattractant-1 (CINC-1) in the intestinal mucosa significantly increased in the indomethacin-treated group compared with the sham group. In addition, the angiotensin II type I receptor was increased in the small intestine after the administration of indomethacin. The development of intestinal lesions in response to indomethacin was prevented by pretreatment with CV-11974 together with significant suppression of the increased level of TBARS, MPO activities and CINC-1. These results indicate that CV-11974 protected against the small intestinal damage elicited by indomethacin, which suggests that angiotensin II/AT1 receptor interaction is involved in the pathogenesis of the intestinal inflammation associated with oxidative stress.

TUMOUR NECROSIS FACTOR: IMPLICATIONS FOR SURGICAL PATIENTS

Tumour necrosis factor alpha (TNF-alpha) is an inflammatory cytokine primarily produced by macrophages. It is a unique protein with contradictive properties; it has the ability to induce cellular death by apoptosis and oncosis, but can also induce cellular regeneration and growth. Genetic polymorphisms in TNFA have been associated with poor outcome in some surgical patients and this may provide a useful tool to screen for high-risk patients. Manipulating TNF-alpha levels in vivo may influence the progression of several pathological conditions. TNF-alpha has anti-cancer properties and has been used to treat cancer patients. Treatment with anti-TNF-alpha drugs and antibodies has been successful in rheumatoid arthritis and other autoimmune diseases, but disappointing in the management of patients with sepsis. This review article focuses on the biological activities, genetic polymorphism of TNFA and the role of TNF-alpha and anti-TNF-alpha treatments, based on animal experiments and clinical trials.

ELR+ CXC chemokines and their receptors (CXC chemokine receptor 1 and CXC chemokine receptor 2) as new therapeutic targets

ELR+ CXC chemokines, by direct interaction with their cell surface receptors CXC chemokine receptor 1 (CXCR1) and CXC chemokine receptor 2 (CXCR2), are believed to be crucially involved in the direct migration and activation of leukocytes. ELR+ CXC chemokines are supposed to play a key role in several inflammatory diseases and this makes ELR+ CXC chemokines and their receptors attractive therapeutic targets. The first aim of this review is to discuss the potential pathological role of ELR+ CXC chemokines in different pathologies, including ulcerative colitis (UC), ischaemia/reperfusion injury (RI), bronchiolitis obliterans syndrome (BOS) and tumor progression. Moreover, the most recently described inhibitors of ELR+ CXC chemokines and their therapeutic indications will be reviewed. Finally, the mode of action and the potential therapeutical use of reparixin, a new potent and selective inhibitor of CXCR1/2 activity, and its chemical derivatives are also discussed.

Inflammatory and redox responses to ischaemia/reperfusion in human skeletal muscle

The objective of this study was to identify cellular and plasma marker(s) of post-I/R (ischaemia/reperfusion) in patients undergoing elective knee surgery where a tourniquet was used to facilitate a bloodless surgical field. We evaluated the inflammatory and redox response by measuring the mRNA levels of ICAM-1 (intercellular cell-adhesion molecule-1), MnSOD (manganese superoxide dismutase), GST-mu (glutathione transferase-mu) and Cu/ZnSOD (copper/zinc superoxide dismutase) in the operated muscle and blood cells pre-operatively (pre-tourniquet) and at various times after reperfusion (tourniquet release). We also measured plasma concentrations of IL (interleukin)-6, IL-8, sICAM-1 (soluble ICAM-1), IL-1beta and TNF-alpha (tumour necrosis factor-alpha) using ELISA. Our results show a strong induction of MnSOD and GST-mu in granulocytes (but not in mononuclear cells or muscle) after reperfusion (2 and 4 h). There was no change in the mRNA level of Cu/ZnSOD after reperfusion. An up-regulation of membrane ICAM-1 in muscle and a decrease in sICAM-1 in plasma were detected after reperfusion. Plasma IL-6 and IL-8 levels (but not TNF-alpha or IL-1beta) increased significantly over baseline at 2 and 4 h after reperfusion. Elevated expression of ICAM-1 in muscle, MnSOD and GST-mu in granulocytes and increased levels of plasma IL-6 and IL-8 may be considered as phase- and cell-specific markers of post-I/R of skeletal muscle in humans.

The essential role of the intestinal microbiota in facilitating acute inflammatory responses

The restoration of blood flow, i.e., reperfusion, is the treatment of choice to save viable tissue following acute ischemia of a vascular territory. Nevertheless, reperfusion can be accompanied by significant inflammatory events that limit the beneficial effects of blood flow restoration. To evaluate the potential role of the intestinal microbiota in facilitating the development of tissue injury and systemic inflammation, germ-free and conventional mice were compared in their ability to respond to ischemia and reperfusion injury. In conventional mice, there was marked local (intestine) and remote (lung) edema formation, neutrophil influx, hemorrhage, and production of TNF-alpha, KC, MIP-2, and MCP-1. Moreover, there was an increase in the concentration of serum TNF-alpha and 100% lethality. In germ-free mice, there was no local, remote, or systemic inflammatory response or lethality after intestinal ischemia and reperfusion and, in contrast to conventional mice, germ-free animals produced greater amounts of IL-10. Similar results were obtained after administration of LPS, i.e., little production of TNF-alpha or lethality and production of IL-10 after LPS in germ-free mice. Blockade of IL-10 with Abs induced marked inflammation and lethality in germ-free mice after ischemia and reperfusion or LPS administration, demonstrating that the ability of these mice to produce IL-10 was largely responsible for their "no inflammation" phenotype. This was consistent with the prevention of reperfusion-associated injury by the exogenous administration of IL-10 to conventional mice. Thus, the lack of intestinal microbiota is accompanied by a state of active IL-10-mediated inflammatory hyporesponsiveness.

Lansoprazole ameliorates intestinal mucosal damage induced by ischemia-reperfusion in rats

AIM: To investigate the protective effect of lansoprazole on ischemia and reperfusion (I/R)-induced rat intestinal mucosal injury in vivo.

METHODS: Intestinal damage was induced by clamping both the superior mesenteric artery and the celiac trunk for 30 min followed by reperfusion in male Sprague-Dawley rats. Lansoprazole was given to rats intraperitoneally 1 h before vascular clamping.

RESULTS: Both the intraluminal hemoglobin and protein levels, as indices of mucosal damage, significantly increased in I/R-groups comparion with those of sham-operation groups. These increases in intraluminal hemoglobin and protein levels were significantly inhibited by the treatment with lansoprazole at a dose of 1 mg/kg. Small intestine exposed to I/R resulted in mucosal inflammation that was characterized by significant increases in thiobarbituric acid-reactive substances (TBARS), tissue-associated myeloperoxidase activity (MPO), and mucosal content of rat cytokine-induced neutrophil chemoattractant-1 (CINC-1). These increases in TBARS, MPO activities and CINC-1 content in the intestinal mucosa after I/R were all inhibited by pretreatment with lansoprazole at a dose of 1 mg/kg. Furthermore, the CINC-1 mRNA expression was increased during intestinal I/R, and this increase in mRNA expression was inhibited by treatment with lansoprazole.

CONCLUSION: Lansoprazole inhibits lipid peroxidation and reduces development of intestinal mucosal inflammation induced by I/R in rats, suggesting that lansoprazole may have a therapeutic potential for I/R injury.

Repertaxin, a novel inhibitor of rat CXCR2 function, inhibits inflammatory responses that follow intestinal ischaemia and reperfusion injury

1. Neutrophils are thought to play a major role in the mediation of reperfusion injury. CXC chemokines are known inducers of neutrophil recruitment. Here, we assessed the effects of Repertaxin, a novel low molecular weight inhibitor of human CXCL8 receptor activation, on the local, remote and systemic injuries following intestinal ischaemia and reperfusion (I/R) in the rat. 2. Pre-incubation of rat neutrophils with Repertaxin (10(-11)-10(-6) m) inhibited the chemotaxis of neutrophils induced by human CXCL8 or rat CINC-1, but not that induced by fMLP, PAF or LTB(4), in a concentration-dependent manner. Repertaxin also prevented CXCL8-induced calcium influx but not CXCL8 binding to purified rat neutrophils. 2. In a model of mild I/R injury (30 min of ischaemia and 30 min of reperfusion), Repertaxin dose-dependently (3-30 mg kg(-1)) inhibited the increase in vascular permeability and neutrophil influx. Maximal inhibition occurred at 30 mg kg(-1). 4. Following severe I/R injury (120 min of ischaemia and 120 min of reperfusion), Repertaxin (30 mg kg(-1)) markedly prevented neutrophil influx, the increase in vascular permeability both in the intestine and the lungs. Moreover, there was prevention of haemorrhage in the intestine of reperfused animals. 5. Repertaxin effectively suppressed the increase in tissue (intestine and lungs) and serum concentrations of TNF-alpha and the reperfusion-associated lethality. 6. For comparison, we also evaluated the effects of an anti-CINC-1 antibody in the model of severe I/R injury. Overall, the antibody effectively prevented tissue injury, systemic inflammation and lethality. However, the effects of the antibody were in general of lower magnitude than those of Repertaxin. 7. In conclusion, CINC-1 and possibly other CXC chemokines, acting on CXCR2, have an important role during I/R injury. Thus, drugs, such as Repertaxin, developed to block the function of the CXCR2 receptor may be effective at preventing reperfusion injury in relevant clinical situations.

A monoclonal antibody against cytokine-induced neutrophil chemoattractant attenuates injury in the small intestine in a model of ruptured abdominal aortic aneurysm

PURPOSE

Ruptured abdominal aortic aneurysm (RAAA) continues to be a major source of aneurysm-related morbidity and mortality. Neutrophils have been implicated in RAAA repair-induced organ injury; however, the agents responsible for neutrophil activation and organ sequestration have not been identified. This study investigated the role of cytokine-induced neutrophil chemoattractant (CINC) in organ injury in an RAAA model.

METHODS

Rats were subjected to 1 hour of hemorrhagic shock with resuscitation, followed by 45 minutes of lower torso ischemia and 2 hours of reperfusion, and randomly were selected to receive saline solution or anti-rat CINC monoclonal antibody at the start of hemorrhagic shock. Another group of animals underwent sham operation, and served as a control group. Intestinal and lung permeability, intestinal and lung myeloperoxidase (MPO) activity, intestinal and lung CINC, and tumor necrosis factor-alpha (TNF-alpha) levels, resuscitation fluid requirements, and histologic mucosal injury were evaluated in all groups.

RESULTS

The RAAA model resulted in increased lung and intestinal permeability to radiolabeled albumin and lung MPO activity (P <.01), with increases in intestinal TNF-alpha (P <.001) and CINC (P <.01) levels, when compared with sham-operated animals. Treatment with anti-rat CINC monoclonal antibody attenuated the increases in intestinal permeability and histologic mucosal injury (P <.01), gut TNF-alpha level (P <.001), and resuscitation fluid volume required (P <.05), without significantly affecting lung and intestinal MPO activity, lung permeability, and intestinal CINC level (P = NS), compared with animals given saline solution.

CONCLUSION

Neutralization of CINC by the anti-rat CINC monoclonal antibody attenuated intestinal injury and induction of intestinal TNF-alpha, but failed to significantly attenuate remote pulmonary injury in this model of RAAA.

Circulating CXC-chemokine concentrations in a murine intestinal ischemia-reperfusion model

BACKGROUND

CXC-chemokines bearing the glutamic acid-leucine-arginine (ELR) motif (ELR+ CXC chemokines) are potent neutrophil chemoattractants and hence may play a role in mucosal injury seen with intestinal ischemia-reperfusion (I/R).

METHODS

Serum concentrations of ELR+ CXC chemokines (keratinocyte-derived chemokine(KC) / CXC ligand (CXCL) 1, macrophage inflammatory protein (MIP)-2/CXCL 2/3, lipopolysaccharide-induced CXC chemokine (LIX) / CXCL5, and lungkine/CXCL15) were measured in a murine intestinal I/R model. Fifteen 4-week-old wild-type mice were studied in three subgroups: sham, ischemia (superior mesenteric artery [SMA] clamping for 60 min) and ischemia-reperfusion (SMA clamping for 60 min followed by reperfusion for 90 min).

RESULTS

Concentrations of KC/CXCL1 and MIP-2/CXCL2/3 in sham-treated animals (145 +/- 123 and 107 +/- 55 pg/mL, respectively) and the ischemia subgroup (646 +/- 413 and 226 +/- 129 pg/mL) were similar, but concentrations were signifcantly higher with reperfusion (6398 +/- 2297, p < .001 and 874 +/- 790 pg/mL, p = .04). LIX/CXCL5 and lungkine/CXCL15 concentrations did not change significantly with ischemia or following I/R. KC/CXCL1 and MIP-2/CXCL2/3 concentrations correlated positively with the severity of mucosal injury and with each other, whereas a negative relationship was observed between LIX/CXCL5 concentrations and microscopic injury scores.

CONCLUSIONS

Development of mucosal injury in intestinal I/R is associated with increased serum concentrations of KC/CXCL1 and MIP-2/CXCL2/3, but not with those of LIX/CXCL5 and lungkine/CXCL15.

Methylene blue in preventing hemodynamic and metabolic derangement following superior mesenteric artery clamping/unclamping: an intratracheal vs. intraperitoneal dose-response study

Intestinal ischemia-reperfusion affects hemodynamics. We studied intratracheal vs. intraperitoneal methylene blue (MB) attenuation of hemodynamic and metabolic deterioration following superior mesenteric artery (SMA) clamping/unclamping. Murine SMAs (5/group) were clamped for 1 h. MB (2, 6, 20, or 60 mg/kg [MB-2, MB-6, MB-20, and MB-60]) was administered intraperitoneally or intratracheally 10 min before unclamping. Observation continued for another 3 h. Circulating xanthine oxidase and base deficit levels doubled among ischemia non-treated and ischemia MB-2- and MB-60-treated groups, blood pressure decreased by 50%, and heart rate increased by 35%, compared to controls (non-clamped/unclamped and non-MB-treated rats, P < 0.01). These three ischemia groups needed 3-fold the amount of fluid to maintain systolic pressure > or =60 mmHg than controls (P < 0.01). Only the MB-6 and MB-20 intraperitoneal and intratracheal regimens similarly afforded hemodynamic stability in ischemic animals; base deficit and resuscitation volumes normalized as well. No drug regimen affected heart rate. We concluded that intraperitoneal and intratracheal MB at specific doses prevented systemic derangement following SMA clamping/unclamping.

The role of chemokines in human cardiovascular pathology: enhanced biological insights

A growing body of experimental evidence supports the pivotal role of chemokines in the pathogenesis of vascular disease. The endothelial expression of monocyte chemoattractant protein-1 (MCP-1) is apparently essential for the earliest cellular responses of atherogenesis. Many atherogenic and anti-atherogenic stimuli can be construed to exert their effects predominantly upon MCP-1 expression within the vascular wall. The atherogenic effects of interleukin-8 (IL-8) seem to be mediated through the down-regulation of the tissue inhibitor of metalloproteinase-1 (TIMP-1). Biological expression of these two important vascular chemokines is further modulated by NF-kappaB. The delineation of these molecular forces that drive atherogenesis increasingly underscores the pivotal role of various chemokines. It is anticipated that more precise delineation of these patterns of gene expression will help to identify molecular targets for the prevention and treatment of atherosclerosis.

Therapeutic potential of monoclonal antibodies in myocardial reperfusion injury

While reperfusion therapy in myocardial infarction is associated with better short- and long-term outcomes, it paradoxically results in reperfusion injury mediated by interactions between leukocytes, endothelial cells, platelets, and the myocardium. Several surface receptors, adhesion molecules, and ligands have been shown to be important in the pathogenesis of myocardial reperfusion injury, and therapeutic strategies employing the use of monoclonal antibodies have been attempted against many of them. These have included monoclonal antibodies against activated complement 5 (C5a) to inhibit leukotaxis, monoclonal antibodies against P-selectin, P-selectin glycoprotein ligand (PSGL)-1, L-selectin and E-selectin to inhibit leukocyte rolling, and monoclonal antibodies against the Mac-1 (CD11b/CD18) receptor and intercellular adhesion molecule (ICAM)-1 to block firm adhesion of leukocytes to endothelial cells. In addition, although initially developed as an antiplatelet agent, the glycoprotein IIb/IIIa receptor antagonist abciximab shows significant ability to diminish or prevent reperfusion injury, presumably through its ability to block the Mac-1 receptor on leukocytes. Finally, monoclonal antibodies have also been tested against several cytokines and adhesion molecules implicated in so-called subacute endothelial activation, including interleukin-8 and vascular cell adhesion molecule (VCAM)-1. Studies in animals evaluating the use of monoclonal antibodies in reperfusion injury against various potential targets have largely been successful; however, studies in humans have been disappointing, underscoring the pitfalls of using animal models for the study of complex diseases. Based upon current knowledge, it is becoming clear that a successful strategy against reperfusion injury will require targeting several pathways at once, rather than attempting to block one final common pathway. In addition, inhibition of subacute endothelial activation through inhibition of transcription factors, namely nuclear factor (NF)-kappa B, may be a prerequisite to significantly reducing the extent of myocardial damage in this condition. The future of monoclonal antibodies in the overall strategy remains unclear. Newer small molecule inhibitors are also under development, and the eventual role of gene therapy remains to be elucidated.