Renal Transplantation With Final Allocation Based on the Virtual Crossmatch

Solid phase immunoassays (SPI) are now routinely used to detect HLA antibodies. However, the flow cytometric crossmatch (FCXM) remains the established method for assessing final donor-recipient compatibility. Since 2005 we have followed a protocol whereby the final allocation decision for renal transplantation is based on SPI (not the FCXM). Here we report long-term graft outcomes for 508 consecutive kidney transplants using this protocol. All recipients were negative for donor-specific antibody by SPI. Primary outcomes are graft survival and incidence of acute rejection within 1 year (AR <1 year) for FCXM+ (n = 54) and FCXM- (n = 454) recipients. Median follow-up is 7.1 years. FCXM+ recipients were significantly different from FCXM- recipients for the following risk factors: living donor (24% vs. 39%, p = 0.03), duration of dialysis (31.0 months vs. 13.5 months, p = 0.008), retransplants (17% vs. 7.3%, p = 0.04), % sensitized (63% vs. 19%, p = 0.001), and PRA >80% (20% vs. 4.8%, p = 0.001). Despite these differences, 5-year actual graft survival rates are 87% and 84%, respectively. AR <1 year occurred in 13% FCXM+ and 12% FCXM- recipients. Crossmatch status was not associated with graft outcomes in any univariate or multivariate model. Renal transplantation can be performed successfully, using SPI as the definitive test for donor-recipient compatibility.

Does Opening the Peritoneum at the Time of Renal Transplanation Prevent Lymphocele Formation?

BACKGROUND

The occurrence of lymphocele formation following renal transplantation is variable, and the optimal approach to treatment remains undefined. Opening the peritoneum at the time of transplantation is one method of decreasing the incidence of lymphocele formation. The purpose of this study was to determine whether creating a peritoneal window at the time of transplantation decreases the incidence of lymphocele formation.

METHODS

We performed a retrospective review of renal transplants conducted at our institution between 2002 and 2004. Records were reviewed to obtain details regarding opening of the peritoneum at the time of transplant and occurrence of lymphocele. Every patient underwent routine ultrasound imaging in the peri-operative period. Graft dysfunction secondary to the lymphocele was the primary indication for intervention. Data were analyzed by chi-square.

RESULTS

During the initial transplant the peritoneum was opened in 35% of patients. The overall incidence of fluid collections, identified by ultrasound, was 24%. Opening the peritoneum did not decrease the incidence of lymphocele. However, more patients with a closed peritoneum required an intervention for a symptomatic lymphocele. In the 11 patients with an open peritoneum and a fluid collection, only one required an intervention. In patients whose peritoneum was left intact, 24% of fluid collections required intervention. Graft survival was equivalent.

CONCLUSION

Creating a peritoneal window at the time of transplantation did not decrease the overall incidence of postoperative fluid collections. However, forming a peritoneal window at the time of transplantation did decrease the incidence of symptomatic lymphocele.

Inhibition of cyclic-3',5'-nucleotide phosphodiesterase abrogates the synergism of hypoxia with lipopolysaccharide in the induction of macrophage TNF-alpha production

BACKGROUND

Local tumor necrosis factor (TNF)-alpha production by resident macrophages (M phi) contributes to posttraumatic tissue injury. Hypoxia decreases cellular cyclic adenosine monophosphate (cAMP) levels and enhances M phi secretion of TNF-alpha following lipopolysaccharide (LPS) stimulation. Thus, tissue hypoxia associated with trauma likely synergizes with proinflammatory mediators in the induction of M phi TNF-alpha production through an influence on cAMP generation or degradation. It is unclear whether elevation of cellular cAMP inhibits LPS-stimulated TNF-alpha production by hypoxic M phi. Moreover, it is unknown whether the synergism of hypoxia with LPS can be abrogated by promotion of cAMP generation or inhibition of cAMP degradation.

METHODS

Rat peritoneal M phi were stimulated with Escherichia coli LPS (20 ng/ml) in a normoxic (room air with 5% CO(2)) or hypoxic (95% N(2) with 5% CO(2)) condition. TNF-alpha levels in cell-free supernatants were measured by enzyme-linked immunoassay. The beta-adrenoceptor agonist isoproterenol (ISP; 5.0 microM) and the adenylate cyclase activator forskolin (FSK; 50 microM) were applied to promote cAMP generation. The nonselective cyclic-3',5'-nucleotide phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX; 1.0 mM) and the PDE III-specific inhibitor milrinone (200 microM) were used to inhibit cAMP degradation. The nondegradable cAMP analogue dibutyryl cAMP (dbcAMP; 100 microM) was applied to further determine the role of PDE. RESULTS. Although hypoxia alone had a minimal effect on TNF-alpha production, it dramatically enhanced LPS-stimulated TNF-alpha production (4.08 +/- 0.28 ng/10(6) cells in hypoxia plus LPS vs 1.63 +/- 0.26 ng/10(6) cells in LPS, 2.5-fold, P < 0.01). Promotion of cAMP generation by either ISP or FSK reduced TNF-alpha production by hypoxic cells. However, neither of these two agents abolished the synergism of hypoxia with LPS (1.68 +/- 0.13 ng/10(6) cells in ISP plus hypoxia plus LPS vs 0.55 +/- 0.04 ng/10(6) cells in ISP plus LPS, threefold; 1.17 +/- 0.03 ng/10(6) cells in FSK plus hypoxia plus LPS vs 0.33 +/- 0.02 ng/10(6) cells in FSK plus LPS, 3.5-fold; both P < 0.01). Inhibition of cAMP degradation with IBMX reduced TNF-alpha production in hypoxic cells and abrogated the synergism (0.31 +/- 0.11 ng/10(6) cells in IBMX plus hypoxia plus LPS vs 0.27 +/- 0.04 ng/10(6) cells in IBMX plus LPS, P > 0.05), and the PDE III inhibitor milrinone had a comparable effect. Moreover, dbcAMP also attenuated TNF-alpha production with abrogation of the synergistic effect of hypoxia (0.56 +/- 0.08 ng/10(6) cells in dbcAMP plus hypoxia plus LPS vs 0.46 +/- 0.04 ng/10(6) cells in dbcAMP plus LPS, P > 0.05).

CONCLUSIONS

The results show that elevation of cellular cAMP, either by promotion of generation or by inhibition of degradation, suppresses LPS-stimulated TNF-alpha production in hypoxic M phi. It appears that hypoxia synergizes with LPS in the induction of M phi TNF-alpha production through PDE-mediated cAMP degradation. Inhibition of PDE may be a therapeutic approach for suppression of synergistic induction of M phi TNF-alpha production by hypoxia and LPS in posttraumatic tissue.

Suppression of tumor necrosis factor alpha production by cAMP in human monocytes: dissociation with mRNA level and independent of interleukin-10

BACKGROUND

Elevation of cellular cAMP inhibits lipopolysaccharide(LPS)-stimulated tumor necrosis factor alpha (TNF-alpha) production and increases the expression of interleukin (IL)-10 in mononuclear cells. TNF-alpha gene expression obligates activation of the transcription factor nuclear factor kappaB (NF-kappaB). Exogenous IL-10 inhibits NF-kappaB in monocytes and thus attenuates TNF-alpha production. We examined the role of endogenous IL-10 in the regulation of NF-kappaB activation and TNF-alpha production in human monocytes by cAMP.

METHODS

Human monocytes were stimulated with Escherichia coli LPS (100 ng/ml) with and without forskolin (FSK, 50 microM) or dibutyryl cyclic AMP (dbcAMP, 100 microM). Cytokine (TNF-alpha and IL-10) release was measured by immunoassay. TNF-alpha mRNA was measured by reverse transcription polymerase chain reaction, and NF-kappaB DNA binding activity was assessed by gel mobility shift assay.

RESULTS

cAMP-elevating agents inhibited LPS-stimulated TNF-alpha release (0.77 +/- 0.13 ng/10(6) cells in LPS + dbcAMP and 0.68 +/- 0.19 ng/10(6) cells in LPS + FSK, both P < 0.05 vs 1.61 +/- 0.34 ng/10(6) cells in LPS alone). Conversely, cAMP enhanced LPS-stimulated IL-10 release (100 +/- 21.5 pg/10(6) cells in LPS + dbcAMP and 110 +/- 25.2 pg/10(6) cells in LPS + FSK, both P < 0.05 vs 53.3 +/- 12.8 pg/10(6) cells in LPS alone). Neither TNF-alpha mRNA expression nor NF-kappaB activation stimulated by LPS was inhibited by the cAMP-elevating agents. Neutralization of IL-10 with a specific antibody did not attenuate the effect of cAMP-elevating agents on TNF-alpha production.

CONCLUSION

The results indicate that cAMP inhibits LPS-stimulated TNF-alpha production through a posttranscriptional mechanism that is independent of endogenous IL-10.

L-arginine attenuates lipopolysaccharide-induced lung chemokine production

Chemokines stimulate the influx of leukocytes into tissues. Their production is regulated by nuclear factor-kappaB (NF-kappaB), an inducible transcription factor under the control of inhibitory factor kappaB-alpha (IkappaB-alpha). We have previously demonstrated that L-arginine (L-Arg) attenuates neutrophil accumulation and pulmonary vascular injury after administration of lipopolysaccharide (LPS). We hypothesized that L-Arg would attenuate the production of lung chemokines by stabilizing IkappaB-alpha and preventing NF-kappaB DNA binding. We examined the effect of L-Arg on chemokine production, IkappaB-alpha degradation, and NF-kappaB DNA binding in the lung after systemic LPS. To block nitric oxide (NO) production, a NO synthase inhibitor was given before L-Arg. LPS induced the production of chemokine protein and mRNA. L-Arg attenuated the production of chemokine protein and mRNA, prevented the decrease in IkappaB-alpha levels, and inhibited NF-kappaB DNA binding. NO synthase inhibition abolished the effects of L-Arg on all measured parameters. Our results suggest that L-Arg abrogates chemokine protein and mRNA production in rat lung after LPS. This effect is dependent on NO and is mediated by stabilization of IkappaB-alpha levels and inhibition of NF-kappaB DNA binding.

Living-unrelated renal transplantation at the University of Wisconsin

Since 1984, we have performed 243 living-unrelated renal transplants at the University of Wisconsin. Rejection occurred in 47% of the patients. Graft loss occurred in 59 patients and 39 patients died. Graft survival in LURD transplants at 10 years is 54% and 43% at 15 years. Patient survival is 68% at 10 years and 54% at 15 years. These long-term results demonstrate that LURD is equivalent to haploidentical renal transplantation and superior to cadaveric transplantation. Husband-to-wife donation demonstrated improved graft survival when compared with wife-to-husband and nonspousal donation. Living-unrelated renal transplantation has been utilized successfully at the University of Wisconsin and may help to alleviate the donor shortage.

Differential cellular immunolocalization of renal tumour necrosis factor-alpha production during ischaemia versus endotoxaemia

Both renal ischaemia and endotoxaemia provoke renal dysfunction and cellular injury. Although the clinical manifestation of each insult is similar (global renal dysfunction), ischaemia and endotoxaemia induce different patterns of cellular injury. Tumour necrosis factor-alpha (TNF-alpha) has been implicated in both types of renal injury; however, it remains unknown whether differential cellular TNF-alpha expression accounts for these changes. We hypothesized that renal glomerular cells and tubular cells differentially express TNF-alpha in response to ischaemia compared with endotoxaemia. To investigate this hypothesis, male Sprague-Dawley rats were anaesthetized and exposed to various time-periods of renal ischaemia, with or without reperfusion (sham operation=negative control), or lipopolysaccharide (LPS) 0.5 mg/kg intraperitoneally (i.p.). The kidneys were harvested following renal injury, and rat TNF-alpha protein expression was determined (by enzyme-linked immunosorbent assay), as were TNF-alpha bioactivity (by WEHI-164 cell clone cytotoxicity assay) and TNF-alpha cellular localization (by immunohistochemistry). TNF-alpha protein expression and TNF-alpha bioactivity peaked following 1 hr of ischaemia and 2 hr of reperfusion (48 +/- 11 pg/mg of protein, P < 0.05, and 12 +/- 0.5 x 10-3 units/mg of protein, P < 0.05, respectively). The concentration of TNF-alpha increased to a similar extent following exposure to LPS; however, while TNF-alpha production following ischaemia-reperfusion injury localized predominantly to renal tubular epithelial cells, animals exposed to LPS demonstrated a primarily glomerular distribution of TNF-alpha production. Hence, the cellular localization of renal TNF-alpha production appears to be injury specific, i.e. renal tubular cells are the primary source of TNF-alpha following an ischaemic insult, whereas LPS induces glomerular TNF-alpha production. The cellular source of TNF-alpha following different insults may have therapeutic implications for targeted inhibition of TNF-alpha production.

Thirty years of clinical trials in acute respiratory distress syndrome

OBJECTIVE

To systematically review clinical trials in acute respiratory distress syndrome (ARDS).

DATA SOURCES

Computerized bibliographic search of published research and citation review of relevant articles.

STUDY SELECTION

All clinical trials of therapies for ARDS were reviewed. Therapies that have been compared in prospective, randomized trials were the focus of this analysis.

DATA EXTRACTION

Data on population, interventions, and outcomes were obtained by review. Studies were graded for quality of scientific evidence.

MAIN RESULTS

Lung protective ventilator strategy is supported by improved outcome in a single large, prospective trial and a second smaller trial. Other therapies for ARDS, including noninvasive positive pressure ventilation, inverse ratio ventilation, fluid restriction, inhaled nitric oxide, almitrine, prostacyclin, liquid ventilation, surfactant, and immune-modulating therapies, cannot be recommended at this time. Results of small trials using corticosteroids in late ARDS support the need for confirmatory large clinical trials.

CONCLUSIONS

Lung protective ventilator strategy is the first therapy found to improve outcome in ARDS. Trials of prone ventilation and fluid restriction in ARDS and corticosteroids in late ARDS support the need for large, prospective, randomized trials.

Chemokines as mediators of diseases related to surgical conditions

Chemokines are important mediators of inflammation. Animal studies suggest that inhibition of chemokine action results in a decrease in inflammation. Novel anti-inflammatory agents directed against chemokines are now available. Surgeons are uniquely positioned to treat multiple chemokine-mediated diseases. In this article, we review the biology and nomenclature of chemokines as well as their role in neutrophil migration. Further, the potential role of chemokines in various diseases related to surgical conditions, including adult respiratory distress syndrome, atherosclerosis, inflammatory bowel disease, and solid organ rejection, is reviewed. Finally, the idea that chemokines could be targets for novel therapeutic agents is discussed.

Adenosine preconditioning reduces both pre and postischemic arrhythmias in human myocardium

INTRODUCTION

Consistently, clinical series record supraventricular tachyarrhythmias in approximately 30% of patients following coronary artery bypass surgery (CABG). Ischemic preconditioning and adenosine preconditioning (Ado-PC) decrease postischemia/reperfusion (I/R) myocardial stunning, infarct size, and pharmacologically induced arrhythmias in all species including man. We hypothesized that adenosine preconditioning would decrease spontaneous pre- and postischemic atrial arrhythmias in human myocardium. The purposes of this study were to determine the effect of in vivo and in vitro Ado-PC on atrial arrhythmias.

METHODS

Human atrial trabeculae were harvested from CABG patients, placed in organ baths, and paced (1 Hz). Developed force (DF) was recorded during simulated I/R (30/45 min). Prior to I/R, trabeculae were treated with Ado (125 microM) for 5 min (in vitro), or patients were treated with Ado (12 mg iv) 5 min (in vivo) prior to harvest of trabeculae. Contraction frequency >4 Hz (defined as atrial tachyarrhythmias) was recorded in all groups pre- and postischemia.

RESULTS

Control trabeculae exhibited increased tachyarrhythmias pre- and postischemia. In vivo and in vitro Ado-PC suppressed both pre- and postischemic arrhythmias.

CONCLUSIONS

Adenosine preconditioning suppresses the frequency of pre- and postischemic tachyarrhythmias against an ischemia/reperfusion insult in human myocardium. This antiarrhythmic effect occurs with both in vitro and in vivo administration of adenosine. Preconditioning with adenosine prior to elective ischemia/reperfusion is a promising strategy of reducing spontaneous atrial arrhythmias in patients undergoing myocardial revascularization.

Differential inducible nitric oxide synthase expression in systemic and pulmonary vessels after endotoxin

Inducible nitric oxide synthase (iNOS) is associated with vascular hypocontractility in systemic vessels after endotoxin lipopolysaccharide (LPS) administration. Although lung iNOS is increased after LPS, its role in the pulmonary circulation is unclear. We hypothesized that whereas iNOS upregulation is responsible for LPS-induced vascular dysfunction in systemic vessels, iNOS does not play a significant role in the pulmonary artery (PA). Using isolated aorta (AO) and PA rings, we examined the effect of nonselective NOS inhibition [N(G)-monomethyl-L-arginine (L-NMMA); 100 micromol/l] and selective iNOS inhibition (aminoguanidine, AG; 100 micromol/l) on alpha(1)-adrenergic-mediated vasoconstriction (phenylephrine; 10(-9) to 10(-3) M) after LPS (Salmonella typhimurium, 20 mg/kg ip). We also determined the presence of iNOS using Western blot and immunohistochemistry. LPS markedly impaired AO contractility (maximal control tension 1,076 +/- 33 mg vs. LPS 412 +/- 39 mg, P < 0.05), but PA contractility was unchanged (control 466 +/- 29 mg vs. LPS 455 +/- 27 mg, P > 0.05). Selective iNOS inhibition restored the AO's response to vasoconstriction (LPS + AG 1,135 +/- 54 mg, P > 0.05 vs. control and P < 0.05 vs. LPS), but had no effect on the PA (LPS + AG 422 +/- 38 mg, P > 0.05 vs. control and LPS). Western blot and immunohistochemistry revealed increased iNOS expression in the AO after LPS, but iNOS was not detected in the PA. Our results suggest that differential iNOS expression after LPS in systemic and pulmonary vessels contributes to the phenomenon of sepsis/endotoxemia-induced systemic hypotension and pulmonary hypertension.

Chlamydia pneumoniae activates nuclear factor kappaB and activator protein 1 in human vascular smooth muscle and induces cellular proliferation

BACKGROUND

Observational data strongly suggest an association between Chlamydia pneumoniae and atherosclerotic cardiovascular disease. However, few studies have mechanistically linked C. pneumoniae to vascular remodeling. The purpose of the present study was to examine the mechanistic relationship between C. pneumoniae and human vascular smooth muscle cell (VSMC) physiology. We sought to determine the influence of human VSMC infection by C. pneumoniae on (1) VSMC proliferation and (2) activation of the proinflammatory and proliferative transcription factors nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1).

MATERIALS AND METHODS

C. pneumoniae was grown and isolated from Hep 2 cells. Human aortic VSMCs were inoculated with C. pneumoniae in the presence and absence of the azalide antibiotic azithromycin. Cell proliferation was assayed by direct cell counting 48 h following infection. Two hours following infection, nuclear extracts were isolated, and activation of both NF-kappaB and AP-1 was assessed by electrophoretic mobility shift assay.

RESULTS

Compared with control, C. pneumoniae infection stimulated VSMC proliferation (P < 0.05) and induced both NF-kappaB and AP-1 DNA binding activity. These effects were eliminated by concurrent treatment with azithromycin.

CONCLUSIONS

VSMC infection with C. pneumoniae activates proliferative intracellular signals and stimulates cell growth. These data implicate C. pneumoniae as a pathogenic mediator and a potential therapeutic target in the prevention of atherosclerotic disease.

Interleukin-1beta deficiency results in reduced NF-kappaB levels in pregnant mice

Interleukin (IL)-1beta-deficient (IL-1beta(-/-)) mice were assessed for cytokine production during pregnancy. A significant reduction in nuclear factor (NF)-kappaB p65 protein content was observed in the uteri and spleens of pregnant IL-1beta(-/-) mice, as demonstrated by immunohistochemistry and Western immunoblot analysis. In addition, electromobility gel shift assay revealed less DNA binding activity of NF-kappaB p65-containing complex in pregnant IL-1beta(-/-) mice. To investigate differences in cytokine production regulated by NF-kappaB, the levels of tumor necrosis factor-alpha, macrophage inflammatory protein-1alpha, and interferon-gamma were measured in the uterine wall, spleen homogenates, and spleen cell cultures obtained from pregnant mice. Endocervical administration of lipopolysaccharide (LPS) increased cytokine levels in both wild-type (IL-1beta(+/+)) and IL-1beta(-/-) animals, but in IL-1beta(-/-) mice this response was 50-75% lower. Splenocytes from nonpregnant mice exhibited decreased LPS-induced cytokine production when primed in vitro with progesterone. This suppression was 25% greater in IL-1beta(-/-) than in IL-1beta(+/+) mice. These data suggest that constitutive NF-kappaB p65 protein synthesis is regulated by IL-1beta, particularly during pregnancy.

Exogenous calcium preconditions myocardium from patients taking oral sulfonylurea agents

We have previously reported that atrial trabeculae from patients taking oral sulfonylurea hypoglycemic agents cannot be preconditioned by transient ischemia, which may, in part, explain the increased cardiovascular mortality historically associated with the use of these agents (J. C. Cleveland et al., 1997, Circulation 96, 29-32). Recently, we reported that clinically accessible and acceptable exogenous Ca(2+) pretreatment protects human atrial trabeculae from subsequent ischemia (B. S. Cain et al., 1998, Ann. Thoracic Surg. 65, 1065-1070). It remains unknown whether this preconditioning strategy could confer protection to trabeculae from patients taking oral sulfonylurea drugs. We therefore hypothesized that exogenous Ca(2+) confers ischemic protection to trabeculae from patients taking oral sulfonylureas. Human atrial trabeculae were suspended in organ baths and field stimulated at 1 Hz, and force development was recorded. Following 90 min equilibration, trabeculae from patients taking oral sulfonylurea agents (n = 6 patients) were subjected to ischemia/reperfusion (I/R; 45/120 min) with or without Ca(2+) (1 mM increase x 5 min) 10 min prior to I/R. I/R decreased postischemic human myocardial contractility in trabeculae from patients on oral hypoglycemics to 15.3 +/- 2.0% baseline developed force (%BDF). Ca(2+) pretreatment increased postischemic human myocardial developed force to 35.3 +/- 2.9 %BDF in these patients (P < 0.05 vs I/R, ANOVA and Bonferroni/Dunn). We conclude that atrial muscle from patients taking oral hypoglycemic agents can be preconditioned with exogenous Ca(2+). This therapy may offer a clinically relevant means to precondition the myocardium of diabetics taking oral hypoglycemic agents prior to clinical interventions such as coronary angioplasty or cardiac bypass.

Inhibition of PARS attenuates endotoxin-induced dysfunction of pulmonary vasorelaxation

Endotoxin (Etx) causes excessive activation of the nuclear repair enzyme poly(ADP-ribose) synthase (PARS), which depletes cellular energy stores and leads to vascular dysfunction. We hypothesized that PARS inhibition would attenuate injury to mechanisms of pulmonary vasorelaxation in acute lung injury. The purpose of this study was to determine the effect of in vivo PARS inhibition on Etx-induced dysfunction of pulmonary vasorelaxation. Rats received intraperitoneal saline or Etx (Salmonella typhimurium; 20 mg/kg) and one of the PARS inhibitors, 3-aminobenzamide (3-AB; 10 mg/kg) or nicotinamide (Nic; 200 mg/kg), 90 min later. After 6 h, concentration-response curves were determined in isolated pulmonary arterial rings. Etx impaired endothelium-dependent (response to ACh and calcium ionophore) and -independent (sodium nitroprusside) cGMP-mediated vasorelaxation. 3-AB and Nic attenuated Etx-induced impairment of endothelium-dependent and -independent pulmonary vasorelaxation. 3-AB and Nic had no effect on Etx-induced increases in lung myeloperoxidase activity and edema. Lung ATP decreased after Etx but was maintained by 3-AB and Nic. Pulmonary arterial PARS activity increased fivefold after Etx, which 3-AB and Nic prevented. The beneficial effects were not observed with benzoic acid, a structural analog of 3-AB that does not inhibit PARS. Our results suggest that PARS inhibition with 3-AB or Nic improves pulmonary vasorelaxation and preserves lung ATP levels in acute lung injury.

Liposomal delivery of heat-shock protein 72 into the heart prevents endotoxin-induced myocardial contractile dysfunction

BACKGROUND

The purposes of this study were to (1) determine whether functional heat-shock protein 72 (HSP-72) may be delivered into the heart, (2) determine whether HSP-72 itself is protective against endotoxin (lipopolysaccharide [LPS]-induced cardiodepression, and (3) compare relative protection and time courses required for protection for thermally induced HSP-72 versus liposomally introduced HSP-72.

METHODS

HSP-72 was introduced (liposomal HSP-72) or induced (heat shock, 42 degrees C x 15 minutes, 24 hours before) in rat heart before LPS administration (0.5 mg/kg intraperitoneal or ex vivo coronary infusion). Western blot analysis for HSP-72 was used to confirm its expression. Left ventricular developed pressure (Langendorff) was used as an index of cardiac function.

RESULTS

Direct intracoronary perfusion of liposomal HSP-72 delivered functioning HSP-72 into the myocardium. LPS induced cardiodepression; however, heat shock pretreatment abolished LPS-induced contractile dysfunction. A direct connection was found between HSP-72 and protection derived from liposomal transfer experiments that similarly reduced LPS-induced cardiodepression.

CONCLUSIONS

(1) HSP-72 prevents LPS-induced myocardial contractile dysfunction, (2) liposomal transfer of HSP-72 into the myocardium provides the first direct mechanistic connection between myocardial HSP-72 and protection against LPS, (3) HSP-72 induction requires 24 hours and liposomal transfer of HSP-72 requires 90 minutes, and (4) HSP-72 may offer a clinically acceptable means of protecting the heart.

Calcium preconditioning, but not ischemic preconditioning, bypasses the adenosine triphosphate-dependent potassium (KATP) channel

BACKGROUND

Recent evidence has implicated the KATP channel as an important mediator of ischemic preconditioning (IPC). Indeed, patients taking oral sulfonylurea hypoglycemic agents (i.e., KATP channel inhibitors) for treatment of diabetes mellitus are resistant to the otherwise profoundly protective effects of IPC. Unfortunately, many cardiopulmonary bypass patients, who may benefit from IPC, are chronically exposed to these agents. Calcium preconditioning (CPC) is a potent form of similar myocardial protection which may or may not utilize the KATP channel in its mechanism of protection. The purpose of this study was to determine whether CPC may bypass the KATP channel in its mechanism of action. If so, CPC may offer an alternative to IPC in patients chronically exposed to these agents.

METHODS

Isolated rat hearts (n = 6-8/group) were perfused (Langendorff) and received KATP channel inhibition (glibenclamide) or saline vehicle 10 min prior to either a CPC or IPC preconditioning stimulus or neither (ischemia and reperfusion, I/R). Hearts were subjected to global warm I/R (20 min/40 min). Postischemic myocardial functional recovery was determined by measuring developed pressure (DP), coronary flow (CF), and compliance (end diastolic pressure, EDP) with a MacLab pressure digitizer.

RESULTS

Both CPC and IPC stimuli protected myocardium against postischemic dysfunction (P < 0.05 vs I/R; ANOVA with Bonferroni/Dunn): DP increased from 52 +/- 4 (I/R) to 79 +/- 2 and 83 +/- 4 mmHg; CF increased from 11 +/- 0.7 to 17 +/- 2 and 16 +/- 1 ml/min; and EDP decreased (compliance improved) from 50 +/- 7 to 27 +/- 5 and 31 +/- 7 mmHg. However, KATP channel inhibition abolished protection in hearts preconditioned with IPC (P < 0.05 vs IPC alone), but not in those preconditioned with CPC (P > 0.05 vs CPC alone).

CONCLUSIONS

(1) Both IPC and CPC provide similar myocardial protection; (2) IPC and CPC operate via different mechanisms; i.e., IPC utilizes the KATP channel whereas CPC does not; and (3) CPC may offer a means of bypassing the deleterious effects of KATP channel inhibition in diabetic patients chronically exposed to oral sulfonylurea hypoglycemic agents.

Reduction of infarct size in the rat heart by LPS preconditioning is associated with expression of angiogenic growth factors and increased capillary density

Inflammation induces the expression of angiogenic growth factors in tissues, which leads to microvascular growth. Bacterial lipopolysaccharide (LPS) provokes a transient inflammatory response in the heart and induces delayed cardiac resistance to post-ischemic contractile dysfunction. In this study, we examined: 1) the effects of LPS on myocardial expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), 2) whether an increase in the density of myocardial microvessels follows the expression of angiogenic growth factors, and 3) the effect of LPS on myocardial resistance to infarction and its relationship with microvascular growth. Rats were treated with LPS (from Salmonella typhimurium, 0.5 mg/kg i.p.). The expression of bFGF and VEGF in the myocardium was examined at 6 and 12 h after LPS treatment by immunofluorescent staining. Myocardial capillary and arteriole densities were determined 3 days after LPS treatment by morphometry, using immunofluorescent staining of von Willebrand factor (a marker protein of endothelial cells) and alpha-smooth muscle actin (a marker protein of smooth muscle cells). To examine cardiac resistance to infarction, hearts were subjected to 40 min of regional ischemia and 2 h of reperfusion by reversible occlusion of left coronary artery at 3 days after LPS treatment. LPS induced cardiac bFGF and VEGF at 6 and 12 h after treatment. The expression of these growth factors was followed by an increase in myocardial capillary density (2032 +/- 78/mm2 vs. 1617 +/- 47/mm2 in saline control, P < 0.05), but not arteriole density, at 3 days. Meanwhile, infarct size was significantly reduced by LPS preconditioning (infarct/left ventricle 12.3 +/- 1.04% vs. 21.7 +/- 1.65% in saline control, 43% reduction, P < 0.05). These results suggest that LPS preconditioning induces cardiac bFGF and VEGF, and an increase in myocardial capillary density. This increased myocardial capillary density is associated with a reduced infarct size after in vivo regional ischemia-reperfusion.

Review article: the role of tumor necrosis factor in renal ischemia-reperfusion injury

Renal ischemia-reperfusion injury induces a cascade of events leading to cellular damage and organ dysfunction. Tumor necrosis factor-alpha (TNF), a potent proinflammatory cytokine, is released from the kidney in response to, and has been implicated in the pathogenesis of, renal ischemia-reperfusion injury. TNF induces glomerular fibrin deposition, cellular infiltration and vasoconstriction, leading to a reduction in glomerular filtration rate (GFR). The signaling cascade through which renal ischemia-reperfusion induces TNF production is beginning to be elucidated. Oxidants released following reperfusion activate p38 mitogen activated protein kinase (p38 MAP kinase) and the TNF transcription factor, NFkappaB, leading to subsequent TNF synthesis. In a positive feedback, proinflammatory fashion, binding of TNF to specific TNF membrane receptors can reactivate NFkappaB. This provides a mechanism by which TNF can upregulate its own expression as well as facilitate the expression of other genes pivotal to the inflammatory response. TNF receptor binding can also induce renal cell apoptosis, the major form of cell death associated with renal ischemia-reperfusion injury. Anti-TNF strategies targeting p38 MAP kinase, NFkappaB, and TNF itself are being investigated as methods of attenuating renal ischemic injury. The control of TNF production and activity represents a realistic goal for clinical medicine.

Inhibition of myocardial TNF-alpha production by heat shock. A potential mechanism of stress-induced cardioprotection against postischemic dysfunction

Overproduction of tumor necrosis factor-alpha (TNF-alpha) contributes to cardiac dysfunction associated with systemic or myocardial stress, such as endotoxemia and myocardial ischemia/reperfusion (I/R). Heat shock has been demonstrated to enhance cardiac functional resistance to I/R. However, the protective mechanisms remain unclear. The purpose of this study was to determine: (1) whether cardiac macrophages express heat shock protein 72 (HSP72) after heat shock, (2) whether induced cardiac HSP72 suppresses myocardial TNF-alpha production during I/R, and (3) whether preservation of postischemic myocardial function by heat shock is correlated with attenuated TNF-alpha production during I/R. Rats were subjected to heat shock (42 degrees C for 15 min) and 24 h recovery. Immunoblotting confirmed the expression of cardiac HSP72. Immunofluorescent staining detected HSP72 in cardiac interstitial cells including resident macrophages rather than myocytes. Global I/R caused a significant increase in myocardial TNF-alpha. The increase in myocardial TNF-alpha was blunted by prior heat shock and the reduced myocardial TNF-alpha level was correlated with improved cardiac functional recovery. This study demonstrates for the first time that heat shock induces HSP72 in cardiac resident macrophages and inhibits myocardial TNF-alpha production during I/R. These observations suggest that inhibition of myocardial TNF-alpha production may be a mechanism by which HSP72 protects the heart against postischemic dysfunction.

Cardiotrophin-1 attenuates endotoxin-induced acute lung injury

Cardiotrophin-1 (CT-1) is a recently discovered member of the gp130 cytokine family, which includes IL-6, IL-11, leukemia inhibitory factor, ciliary neurotrophic factor, and oncostatin M. Recent evidence suggests that, like other members of this family, CT-1 may possess anti-inflammatory properties. We hypothesized that in vivo CT-1 administration would attenuate endotoxin (ETX)-induced acute lung injury. We studied the effects of CT-1 (100 microgram/kg ip, 10 min prior to ETX) in a rat model of ETX-induced acute lung injury (Salmonella typhimurium lipopolysaccharide, 20 mg/kg ip). Six hours after ETX, lungs were harvested for determination of neutrophil accumulation (myeloperoxidase, MPO, assay) and lung edema (wet-to-dry weight ratio). Mechanisms of pulmonary vasorelaxation were examined in isolated pulmonary artery rings at 6 h by interrogating endothelium-dependent (response to acetylcholine) and endothelium-independent (response to sodium nitroprusside) relaxation following alpha-adrenergic (phenylephrine)-stimulated preconstriction. CT-1 abrogated the endotoxin-induced lung neutrophil accumulation: 2.3 +/- 0.2 units MPO/g wet lung (gwl) vs 6. 3 +/- 0.3 units MPO/gwl in the ETX group (P < 0.05 vs ETX, P > 0.05 vs control). Similarly, CT-1 prevented ETX-induced lung edema: wet-to-dry-weight ratio, 4.473 +/- 0.039 vs 4.747 +/- 0.039 in the ETX group (P < 0.05 vs ETX, P > 0.05 vs control). Endotoxin caused significant impairment of both endothelium-dependent and -independent pulmonary vasorelaxation, and CT-1 attenuated this injury. Thus, cardiotrophin-1 possesses significant anti-inflammatory properties in a model of endotoxin-induced acute lung injury.

LPS-Induced NF-kappaB activation and TNF-alpha release in human monocytes are protein tyrosine kinase dependent and protein kinase C independent

BACKGROUND

Tumor necrosis factor alpha (TNF-alpha) is an important mediator of septic shock. Endotoxin (LPS) signal transduction in human monocytes leads to activation of nuclear factor-kappa B (NF-kappaB) and TNF-alpha release. Previous studies have implicated activation of both protein kinase C (PKC) and protein tyrosine kinases (PTK) in LPS-induced NF-kappaB activation and TNF-alpha production. We hypothesized that inhibition of either PKC or PTK would decrease LPS-induced NF-kappaB DNA binding and TNF-alpha release in human monocytes.

MATERIALS AND METHODS

Human monocytes were stimulated with PMA (50 ng/ml) alone or LPS (100 ng/ml) with and without a nonspecific serine/threonine protein kinase inhibitor staurosporine (Stauro), a specific pan-PKC inhibitor bisindolylmaleimide (Bis), or an inhibitor of PTK genistein (Gen). TNF-alpha release in culture supernatants was measured by an ELISA. NF-kappaB DNA binding was evaluated by electrophoretic mobility shift assay.

RESULTS

LPS increased NF-kappaB DNA binding and TNF-alpha release in human monocytes. Nonspecific protein kinase inhibition inhibited NF-kappaB activation and TNF-alpha release, while specific PKC inhibition with Bis had no effect on LPS-induced NF-kappaB DNA binding or TNF-alpha release. PTK inhibition with Gen attenuated both LPS-induced NF-kappaB DNA binding and TNF-alpha production in human monocytes. Direct activation of PKC with PMA induced both NF-kappaB activation and TNF-alpha production by human monocytes.

CONCLUSIONS

These results suggest that LPS-induced NF-kappaB activation and TNF-alpha release in human monocytes are independent of PKC activity. Furthermore, our results provide evidence that PTK plays a role in LPS-induced NF-kappaB activation and TNF-alpha release in human monocytes and thus could be a potential therapeutic target in inflammatory states.

The NFkappaB inhibitory peptide, IkappaBalpha, prevents human vascular smooth muscle proliferation

BACKGROUND

Vessel injury results in an inflammatory response characterized by the elaboration of cytokines and growth factors, which ultimately influence vascular smooth muscle cell (VSMC) growth and contribute to atherogenesis. Nuclear factor-kappa B (NFkappaB) is a central transcription factor important in mediating stress and inflammatory-induced signals. We hypothesized that strategies aimed at inhibiting NFkappaB would abrogate mitogen-induced human VSMC proliferation.

METHODS

Human aortic VSMC were stimulated with basic fibroblast growth factor (FGF) and tumor necrosis factor-alpha (TNF), and proliferation was quantified by a colormetric assay. The influence of NFkappaB on VSMC proliferation was examined by both nonspecific NFkappaB blockade with calpain inhibitor-1 (CI-1) and dexamethasone (Dex) and specific NFkappaB blockade with liposomal delivery of the NFkappaB inhibitory peptide, IkappaBalpha.

RESULTS

FGF and TNF induced concentration-dependent VSMC proliferation (p < 0.002). Neither CI-1, Dex, nor liposomal IkappaBalpha influenced proliferation of unstimulated VSMC. However, both FGF- and TNF-stimulated VSMC proliferation was inhibited to the level of control with CI-1, Dex, and liposomal IkappaBalpha (p < 0.001).

CONCLUSION

The mitogenic effect of FGF and TNF on human arterial VSMC may be prevented by inhibiting NFkappaB. Furthermore, liposomal delivery of endogenous inhibitory proteins such as IkappaBalpha may represent a novel, therapeutically accessible method for selective transcriptional suppression in the response to vascular injury.

Utilization of endoscopic inoculation in a mouse model of intrauterine infection-induced preterm birth: role of interleukin 1beta

A novel murine model of intrauterine infection/inflammation-induced preterm birth based on direct endoscopic intracervical inoculation is described. Using this model, we investigated infection-induced premature pregnancy loss in normal and interleukin (IL) 1beta-deficient mice. Seventy-four CD-1, HS, C57BL/6J wild type (IL-1beta+/+), and C57BL/6J IL-1beta-deficient (IL-1beta-/-) mice were inoculated intracervically using a micro-endoscope, at a time corresponding to 70% of average gestation. Intracervical injection of lipopolysaccharide (LPS) or Escherichia coli reliably induced premature birth: 100% of mice intracervically injected with LPS and 92% of mice with a positive endometrial E. coli culture delivered prematurely within 36 h after inoculation. No losses were observed in mice inoculated with saline. Pregnancy loss was associated with increased uterine tissue cyclooxygenase-2 gene expression and uterine content of IL-1beta, tumor necrosis factor alpha, macrophage inflammatory protein-1alpha, and IL-6, as well as elevation of nuclear factor-kappaB activity in uterine tissues. Although IL-1beta-/- mice exhibited decreased uterine cytokine production in response to bacteria and LPS, IL-1beta deficiency did not affect the rate of pregnancy loss. This model using direct intracervical bacterial or LPS inoculation is useful for studying preterm pregnancy loss in genetically altered mice in order to develop novel interventions for infection-associated preterm labor.

p38 MAPK inhibition decreases TNF-alpha production and enhances postischemic human myocardial function

INTRODUCTION

TNF-alpha is a proinflammatory cytokine implicated in myocardial dysfunction following ischemia/reperfusion (I/R). I/R results in myocardial production of TNF-alpha and TNF-alpha suppresses myocardial contractility. p38 mitogen-activated protein kinase (MAPK) is a redox-sensitive protein kinase involved in intracellular signaling leading to TNF-alpha production. It remains unknown if the human heart produces TNF-alpha after I/R and, if so, whether p38 MAPK is involved.

HYPOTHESIS

p38 MAPK inhibition enhances human myocardial post-I/R contractile function by inhibition of myocardial TNF-alpha production.

METHODS

Human atrial trabeculae were suspended in organ baths, field simulated at 1 Hz, and force development was recorded. Following a 90-min equilibration, trabeculae were exposed to a p38 MAPK inhibitor (SB 203580, 1 microM) or vehicle (each n = 6) prior to simulated ischemia (45 min hypoxia, substrate-free, rapid pacing at 3 Hz) followed by 120 min reoxygenation. Myocardial TNF-alpha levels were measured by ELISA at end reoxygenation.

RESULTS

I/R increased human myocardial TNF-alpha levels from 26.9 +/- 9.3 to 83.9 +/- 19.2 pg/g wet tissue (P < 0.05 perfusion vs I/R; ANOVA Bonferroni/Dunn), while p38 MAPK inhibition decreased post-I/R myocardial TNF-alpha levels to 32.3 +/- 8.0 pg/g wet tissue (P > 0.05 p38 MAPK inhibition vs I/R). p38 MAPK inhibition improved postischemic force development from 18.5 +/- 2.1 to 37.0 +/- 2.0% baseline developed force (%BDF; P < 0.05 I/R vs p38 MAPK inhibition).

CONCLUSIONS

(1) The human heart produces TNF-alpha after I/R, (2) p38 MAPK mediates myocardial I/R-induced TNF-alpha production, (3) p38 MAPK inhibition limits functional impairment after I/R, and (4) inhibition of ischemia-induced TNF-alpha production may represent a potent therapeutic strategy for improving myocardial function after angioplasty, coronary bypass, or heart transplantation.

Adrenergic induction of bimodal myocardial protection: signal transduction and cardiac gene reprogramming

This study tested the hypothesis that in vivo norepinephrine (NE) treatment induces bimodal cardiac functional protection against ischemia and examined the roles of alpha1-adrenoceptors, protein kinase C (PKC), and cardiac gene expression in cardiac protection. Rats were treated with NE (25 micrograms/kg iv). Cardiac functional resistance to ischemia-reperfusion (25/40 min) injury was examined 30 min and 1, 4, and 24 h after NE treatment with the Langendorff technique, and effects of alpha1-adrenoceptor antagonism and PKC inhibition on the protection were determined. Northern analysis was performed to examine cardiac expression of mRNAs encoding alpha-actin and myosin heavy chain (MHC) isoforms. Immunofluorescent staining was performed to localize PKC-betaI in the ventricular myocardium. NE treatment improved postischemic functional recovery at 30 min, 4 h, and 24 h but not at 1 h. Pretreatment with prazosin or chelerythrine abolished both the early adaptive response at 30 min and the delayed adaptive response at 24 h. NE treatment induced intranuclear translocation of PKC-betaI in cardiac myocytes at 10 min and increased skeletal alpha-actin and beta-MHC mRNAs in the myocardium at 4-24 h. These results demonstrate that in vivo NE treatment induces bimodal myocardial functional adaptation to ischemia in a rat model. alpha1-Adrenoceptors and PKC appear to be involved in signal transduction for inducing both the early and delayed adaptive responses. The delayed adaptive response is associated with the expression of cardiac genes encoding fetal contractile proteins, and PKC-betaI may transduce the signal for reprogramming of cardiac gene expression.

Liposomal delivery of purified inhibitory-kappaBalpha inhibits tumor necrosis factor-alpha-induced human vascular smooth muscle proliferation

Vessel injury results in the elaboration of various cytokines, including tumor necrosis factor-alpha (TNF-alpha), which may influence vascular smooth muscle cell (VSMC) function and contribute to atherogenesis. We tested the hypothesis that TNF-alpha-induced VSMC proliferation requires activation of the transcription factor nuclear factor-kappaB (NF-kappaB), which could be prevented by delivery of the NF-kappaB inhibitory peptide, IkappaBalpha. TNF-alpha induced concentration-dependent human VSMC proliferation, and neutralizing antibody to interleukin-6 reduced TNF-alpha-induced VSMC proliferation by 65%. In TNF-alpha-stimulated VSMCs, there was a 3-fold increase in NF-kappaB-dependent luciferase reporter activity that was associated with degradation of IkappaBalpha. To determine an essential role for NF-kappaB in TNF-alpha-induced VSMC proliferation, recombinant IkappaBalpha was introduced into VSMCs via liposomal delivery. Under these conditions, TNF-alpha-induced NF-kappaB nuclear translocation and DNA binding were inhibited, NF-kappaB-dependent luciferase activity was reduced by 50%, there was no degradation of native IkappaBalpha detected, interleukin-6 production was reduced by 54%, and VSMC proliferation was decreased by 60%. In conclusion, the mitogenic effect of TNF-alpha on human arterial VSMCs is dependent on NF-kappaB activation and may be prevented by exogenously delivered IkappaBalpha. Furthermore, liposomal delivery of endogenous inhibitory proteins may represent a novel, therapeutically accessible method for selective transcriptional suppression in the response to vascular injury.

Interleukin-10 inhibits postinjury tumor necrosis factor-mediated human vascular smooth muscle proliferation

BACKGROUND

Both ischemic and direct vascular injury (angioplasty) result in the elaboration of proinflammatory substances, including tumor necrosis factor alpha (TNF), which may regulate vascular smooth muscle cell (VSMC) proliferation and promote vessel stenosis. Interleukin-10 (IL-10) is a pleiotropic cytokine with potent antiinflammatory effects in many cells lines. We hypothesized that IL-10 could be used therapeutically to influence vascular remodeling by inhibiting TNF-induced VSMC proliferation. The purposes of this study were (1) to determine whether human myocardium produces endogenous TNF in response to ischemia-reperfusion, (2) to examine the effect of TNF on human arterial smooth muscle proliferation, and (3) to explore the potential therapeutic effect of IL-10 on unstimulated and TNF-stimulated VSMC proliferation.

MATERIALS AND METHODS

Right atrial muscle was obtained from patients undergoing elective cardiac surgery. Atrial muscle was subjected to simulated ischemia and reperfusion in vitro and TNF was measured by immunoassay. Human aortic VSMCs were isolated and cultured. Proliferation assays were performed to determine the effect of TNF and IL-10 on VSMC growth.

RESULTS

Ischemia-reperfusion resulted in an increase in atrial myocellular TNF (94.5 +/- 15.8 pg/g wet tissue versus control 12.9 +/- 4.4 pg/g wet tissue, P < 0.002). Compared with control, TNF stimulated concentration-dependent VSMC proliferation (P < 0.005). IL-10 alone did not influence VSMC growth. However, following TNF stimulation, IL-10 inhibited VSMC growth at a dose as low as 0.1 pg/ml (P < 0.005).

CONCLUSIONS

Ischemia-reperfusion insult results in increased endogenous myocardial TNF accumulation. TNF stimulates VSMC growth which is abrogated by physiologically relevant levels of IL-10. This antiinflammatory cytokine may prove to be an effective therapeutic agent in regulating vessel wall remodeling following both ischemic and direct cardiovascular injury.

Interleukin-10 stabilizes inhibitory kappaB-alpha in human monocytes

Interleukin-10 (IL-10) protects animals from lethal endotoxemia. This beneficial effect is mediated, in part, by inhibition of inflammatory cytokine production, including tumor necrosis factor-alpha (TNF-alpha). Evidence suggests that IL-10 may inhibit activation of the transcription factor nuclear factor-kappaB (NF-kappaB) through an unknown mechanism. NF-kappaB activation in response to inflammatory signals is dependent upon degradation of its associated inhibitory peptide, inhibitory kappaB-alpha (IkappaB-alpha). We hypothesized that IL-10 prevents human monocyte NF-kappaB activation and resultant TNF-alpha production by stabilization of IkappaB-alpha. The purpose of this study was to determine the effect of IL-10 on lipopolysaccharide (LPS)-induced human monocyte TNF-alpha production, NF-kappaB activation, and IkappaB-alpha degradation. Monocytes were isolated from human donors. Cells were stimulated with endotoxin (LPS, 100 ng/mL) with and without human IL-10 (10 ng/mL). Following stimulation, TNF-alpha was measured in cell supernatants by ELISA, NF-kappaB activity by electrophoretic mobility shift assay, and IkappaB-alpha levels by Western blot. We observed that after LPS stimulation of human monocytes, TNF-alpha increased to 798+/-67 pg/mL (p < .001 versus control). IL-10 attenuated LPS-stimulated TNF-alpha production (297+/-54; p < .001 versus LPS alone). After LPS stimulation in human monocytes, IkappaB-alpha protein levels decreased, and NF-kappaB DNA binding increased. IL-10 pretreatment prevented LPS-induced decreases in IkappaB-alpha protein levels and attenuated NF-kappaB DNA binding. IL-10 appears to prevent activation of NF-kappaB by preserving IkappaB-alpha protein levels, leading to a reduction in TNF-alpha release.

Ischemic preconditioning decreases postischemic myocardial tumor necrosis factor-alpha production. Potential ultimate effector mechanism of preconditioning

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is an autocrine contributor to myocardial dysfunction and cardiomyocyte death in ischemia-reperfusion (I/R) injury, sepsis, chronic heart failure, and cardiac allograft rejection. Cardiac resident macrophages, infiltrating leukocytes, and cardiomyocytes themselves produce TNF-alpha. Although adenosine reduces macrophage TNF-alpha production and protects myocardium against I/R, it remains unknown whether ischemic preconditioning, which is mediated by adenosine, decreases postischemic myocardial TNF-alpha production.

METHODS AND RESULTS

Isolated rat hearts were crystalloid perfused with the Langendorff method and subjected to global, normothermic I/R (20/40 minutes), with or without prior transient ischemic preconditioning (5 minutes) or adenosine pretreatment. Postischemic cardiac TNF-alpha (ELISA) and function were determined (Langendorff). I/R increased cardiac TNF-alpha and impaired myocardial function. Ischemic preconditioning or adenosine decreased myocardial TNF-alpha and improved postischemic functional recovery. Sequestration of myocardial TNF-alpha (TNF binding protein) during the I/R experiments similarly improved postischemic myocardial function.

CONCLUSIONS

This study constitutes the initial demonstration that in addition to its other beneficial effects, preconditioning decreases postischemic myocardial TNF-alpha, an autocrine contributor to postischemic myocardial dysfunction. Reduced myocardial TNF-alpha production may represent the distal effector mechanism of preconditioning.

Therapeutic implications of interleukin-10 in surgical disease

Pharmacological therapy of surgical disease often involves manipulating the physiologic balance between pro- and anti-inflammatory responses. Many agents target only one aspect of the inflammatory cascade. Originally identified as a protein elaborated by T-lymphocytes, IL-10 appears to globally inhibit cytokine production. The purpose of this manuscript is to examine the immunomodulatory and anti-inflammatory effects of interleukin-10 (IL-10) in an attempt to define the clinical utility of IL-10, both as a marker of and as a therapeutic strategy for intervention in inflammatory and immune-mediated diseases. IL-10 is elaborated from multiple sources and has diverse cellular effects to regulate immune and inflammatory responses. Accumulating evidence suggests that the anti-inflammatory influence of IL-10 observed at the cellular level may be manipulated to impact the immune and inflammatory-mediated responses associated with injury and sepsis, gastrointestinal and cardiovascular disease, and transplantation. In conclusion, IL-10 is an important mediator of immune and anti-inflammatory responses in surgical disease and, as such, has therapeutic promise as an immunomodulator and as an anti-inflammatory agent.

Human myocardial tissue TNFalpha expression following acute global ischemia in vivo

Although human myocardial TNFalpha levels are increased during the ischemia associated with chonic heart failure, it remains unknown whether an acute global ischemic insult further increases TNFalpha expression in human cardiac myocytes. To study this, biopsies of human myocardium were obtained before and after cardiopulmonary bypass (in vivo acute global ischemia), and myocardial TNFalpha levels were determined by ELISA and cytotoxicity assay (WEHI-164 clone 13 cell line). TNFalpha was immunolocalized by immunohistochemistry. Results indicate that cardiopulmonary bypass induces an increase in human myocardial TNFalpha by both ELISA and cytotoxicity assays. Immunolocalization revealed that prior to cardiopulmonary bypass TNFalpha was located predominantly in the myocardial interstitial cells; however, following bypass, increased TNFalpha was observed in the cardiocytes themselves. Locally-produced myocardial TNFalpha may be an important contributor to myocardial functional depression and injury following acute ischemia. Targeted anti-TNFalpha therapy in the treatment of cardiac ischemic injury may further elucidate its clinical relevance.

Increased levels of myocardial IkappaB-alpha protein promote tolerance to endotoxin

Endotoxin [lipopolysaccharide (LPS)] causes tumor necrosis factor-alpha (TNF-alpha)-mediated myocardial contractile depression. Tolerance to the cardiac toxicity of LPS can be induced by a prior exposure to LPS or by pretreatment with glucocorticoids. The mechanisms by which the myocardium acquires tolerance to LPS remain unknown. LPS causes phosphorylation and degradation of inhibitory kappaB-alpha (IkappaB-alpha), releasing nuclear factor-kappaB (NF-kappaB) to activate TNF-alpha gene transcription. We hypothesized that LPS induces supranormal synthesis of myocardial IkappaB-alpha protein and thus renders the myocardium tolerant to subsequent LPS. Rats were challenged with LPS after pretreatment with LPS, dexamethasone, or saline. In saline-pretreated rats, LPS caused a rapid decrease in myocardial IkappaB-alpha protein levels, activation of NF-kappaB, and increased TNF-alpha production. These events were followed by myocardial contractile depression. After the initial decrease in myocardial IkappaB-alpha, IkappaB-alpha protein levels rebounded to a level greater than control levels by 24 h. Dexamethasone pretreatment similarly increased myocardial IkappaB-alpha protein levels. In rats pretreated with either LPS or dexamethasone, myocardial IkappaB-alpha protein levels remained similar to control levels after LPS challenge. The preserved level of myocardial IkappaB-alpha protein was associated with diminished NF-kappaB activation, attenuated myocardial TNF-alpha production, and improved cardiac contractility. We conclude that LPS and dexamethasone upregulate myocardial IkappaB-alpha protein expression and that an increased level of myocardial IkappaB-alpha protein may promote cardiac tolerance to LPS by inhibition of NF-kappaB intranuclear translocation and myocardial TNF-alpha production.

Class II cytokine receptor ligands inhibit human vascular smooth muscle proliferation

BACKGROUND

Vessel injury provokes the release of proinflammatory cytokines and growth factors that influence vascular smooth muscle cell (VSMC) proliferation and migration. Produced by T lymphocytes, interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) both have immunoregulatory functions and act on similar receptors, designated class II cytokine receptors. We hypothesized that the class II cytokine receptor participates in vascular remodeling by inhibiting VSMC proliferation. The purposes of this study were to determine the influence of class II cytokine receptor stimulation on (1) unstimulated, (2) cytokine-stimulated, and (3) growth factor-stimulated VSMC proliferation.

METHODS

Human aortic VSMCs were isolated and cultured. VSMCs were treated with IL-10 or IFN with or without tumor necrosis factor-alpha (TNF-alpha) or basic fibroblast growth factor (FGF). Proliferation was quantified by colormetric assay.

RESULTS

Compared to control, both TNF and FGF stimulated concentration-dependent VSMC proliferation (P < .005). IL-10 and IFN alone had no effect on unstimulated cell growth. With TNF or FGF stimulation, both IL-10, at a dose as low as 10 fg/ml, and IFN, at a dose as low as 1.0 U/ml, inhibited cell growth (P < .001).

CONCLUSIONS

The class II cytokine receptor ligands, IL-10 and IFN, inhibit cytokine-(TNF) and growth factor-(FGF) induced VSMC proliferation. The class II cytokine receptor may provide a novel therapeutic target in regulating vessel wall remodeling after vascular injury.

Hydrogen peroxide induces tumor necrosis factor alpha-mediated cardiac injury by a P38 mitogen-activated protein kinase-dependent mechanism

BACKGROUND

Oxidant stress caused by ischemia or endotoxemia induces myocardial dysfunction and cardiomyocyte death; however, mechanisms responsible remain unknown. We hypothesized that hydrogen peroxide (H2O2) induces myocardial dysfunction and cardiomyocyte death via P38 mitogen-activated protein kinase (MAPK)-mediated myocardial tumor necrosis factor (TNF) production.

METHODS

Langendorff perfused rat hearts (6/group) were subjected to oxidant stress (H2O2 infusion; 300 mmol/L x 80 minutes), with and without prior infusion of a specific P38 kinase MAPK inhibitor (P38i = 1 mmol/L/min x 5 minutes) or TNF neutralization (20 mg TNF binding protein (BP)/min x 80 minutes). Developed pressure (DP), coronary flow, and end-diastolic pressure were continuously recorded. Myocardial creatine kinase (CK) loss was measured in the coronary effluent, and tissue TNF was measured in myocardial homogenates.

RESULTS

Eighty minutes of H2O2 infusion induced a 6.5-fold increase in myocardial TNF production, which was associated with a 70% decrease in DP and increase in CK loss. P38 MAPK inhibition or TNF-BP decreased myocardial TNF production, cardiomyocyte death, and myocardial dysfunction.

CONCLUSIONS

These results demonstrate that H2O2 alone induces myocardial TNF production. P38 MPAK is an oxidant-sensitive enzyme that mediates oxidant-induced myocardial TNF production, cardiac dysfunction, and cardiomyocyte death.

TNF-alpha and myocardial depression in endotoxemic rats: temporal discordance of an obligatory relationship

Exogenous tumor necrosis factor-alpha (TNF-alpha) induces delayed myocardial depression in vivo but promotes rapid myocardial depression in vitro. The temporal relationship between endogenous TNF-alpha and endotoxemic myocardial depression is unclear, and the role of TNF-alpha in this myocardial disorder remains controversial. Using a rat model of endotoxemia not complicated by shock, we sought to determine 1) the temporal relationship of changes in circulating and myocardial TNF-alpha with myocardial depression, 2) the influences of protein synthesis inhibition or immunosuppression on TNF-alpha production and myocardial depression, and 3) the influence of neutralization of TNF-alpha on myocardial depression. Rats were treated with lipopolysaccharide (LPS, 0.5 mg/kg ip). Circulating and myocardial TNF-alpha increased at 1 and 2 h, whereas myocardial contractility was depressed at 4 and 6 h. Pretreatment with cycloheximide or dexamethasone abolished the increase in circulating and myocardial TNF-alpha and preserved myocardial contractile function. Similarly, treatment with TNF binding protein immediately after LPS prevented myocardial depression. We conclude that endogenous TNF-alpha mediates delayed myocardial depression in endotoxemic rats and that inhibition of TNF-alpha production or neutralization of TNF-alpha preserves myocardial contractile function in endotoxemia.

Nitric oxide downregulates lung macrophage inflammatory cytokine production

BACKGROUND

Inflammatory cytokine production contributes to lung injury after lung ischemia reperfusion and during lung transplant rejection. Although nitric oxide has been demonstrated to reduce lung injury associated with the adult respiratory distress syndrome, it remains unknown whether the mechanism of nitric oxide's beneficial effects involves reducing lung macrophage inflammatory cytokine production. The purpose of this study was to determine whether nitric oxide downregulates lung macrophage inflammatory cytokine production.

METHODS

Lung macrophages were harvested by bronchoalveolar lavage (10(6) macrophage per milliliter from normal Sprague-Dawley rats, 6 animals per group) and treated under ex vivo tissue culture conditions with the nitric oxide releasing compound S-nitoso-N-acetyl-D, L-penicillamine (0, 10(-5) 10(-4), 10(-3), 10(-2) mol/L) before induction of inflammatory cytokines with endotoxin, (50 ng/mL for 24 hours). Supernatants were assayed for inflammatory cytokine production (tumor necrosis factor alpha, interleukin-1beta) by enzyme-linked immunosorbent assay.

RESULTS

Continuous nitric oxide release by S-nitoso-N-acetyl-D, L-penicillamine decreased lung macrophage tumor necrosis factor-alpha and interleukin-1beta production in a dose-dependent fashion (6 rats per group; data were analyzed for significance [p < 0.05] using two-way analysis of variance with Tukey's post-hoc correction).

CONCLUSIONS

Nitric oxide decreases inflammatory cytokine production by lung macrophage. The mechanism of nitric oxide's beneficial effects may be partially attributable to decreased production of inflammatory cytokines. Nitric oxide may serve an expanded role for reducing inflammatory cytokine production during acute lung injury, ischemia-reperfusion-induced inflammation, or lung transplant rejection.

Genes don't count

It is the regulation of gene expression that determines phenotype and cellular response. Several families of proteins control gene expression in cells and influence the pathogenesis of multiple organ failure, the acute phase response, atherosclerosis, and graft-vs-host disease. Understanding the basics of the regulation of gene transcription will allow the knowledgeable surgeon to target gene expression as a therapeutic modality in multiple diseases. We examine nuclear factor kappa B as an example of a transcription factor that is involved in multiple surgical diseases and has pharmacological inhibitors available to knowledgeable surgeons.

Calcium preconditioning in human myocardium

BACKGROUND

Ischemic stress and other protein kinase C (PKC)-linked receptor stimuli can induce rapid cardiac protection against ischemia-reperfusion injury. We and others have demonstrated that exogenous calcium (Ca2+) pretreatment confers PKC-mediated cardiac functional and infarct protection in animal models, but it remains unknown whether Ca2+ preconditioning confers similar postischemic functional protection in human myocardium, and, if so, whether the mechanism is mediated by PKC. We postulated that Ca2+ preconditioning confers ischemic tolerance to human myocardium by a PKC-dependent mechanism.

METHODS

Human atrial trabeculae were suspended in organ baths and paced at 1 Hz, and force development was recorded. After 90 minutes of equilibration, all trabeculae were subjected to ischemia (45 minutes) and reperfusion (120 minutes). Exogenous CaCl2 (3.0 mmol/L for 5 minutes) or vehicle (saline solution) was administered before simulated ischemia, with or without concurrent PKC inhibition (bisindolylmaleimide I, 150 nmol/L).

RESULTS

Ischemia-reperfusion resulted in decreased postischemic developed force, Ca2+ preconditioning protected human myocardium against ischemia-reperfusion injury (p < 0.05 versus control ischemia-reperfusion), and concurrent PKC inhibition abolished the salutary effect of Ca2+ preconditioning in human myocardium (p < 0.05 versus Ca2+ preconditioning).

CONCLUSIONS

Preconditioning with Ca2+ represents a potent means of accessing PKC-mediated protection of the human myocardium against ischemia-reperfusion injury.

Interleukin-10 inhibits human vascular smooth muscle proliferation

Arterial injury results in the elaboration of pro-inflammatory substances including cytokines and peptide growth factors which act to modify vascular smooth muscle (VSMC) proliferation and migration with resultant vessel stenosis. Produced by T-lymphocytes and macrophages, interleukin-10 (IL-10) is an anti-inflammatory cytokine in several cell lines. We hypothesized that IL-10 may participate in vascular remodeling by inhibiting VSMC proliferation. Human aortic VSMCs were isolated and cultured. Proliferation assays were performed to determine the effect of the effect of IL-10 on (1) unstimulated, (2) cytokine (tumor necrosis factor-alpha: TNF alpha)-stimulated, and (3) growth factor (basic fibroblast growth factor: bFGF)-stimulated VSMC proliferation. Compared to control, both TNF alpha and bFGF-stimulated VSMC proliferation (P < 0.002). IL-10 alone had no effect on cell growth. However, with TNF alpha or bFGF-stimulation, physiologic doses of IL-10 inhibited both VSMC DNA synthesis and VSMC growth (P < 0.001). Furthermore, IL-10 was effective in inhibiting TNF alpha-induced proliferation at a dose as low as 10 fg/ml (P < 0.001) and bFGF-induced proliferation at a dose as low as 1 pg/ml (P < 0.001). In conclusion, TNF alpha and bFGF stimulate human VSMC growth. IL-10 potently abrogates the proliferative response to these atherogenic mitogens. IL-10 might represent an endogenous source of immune-mediated atherprotection and when given exogenously, may prove to be a novel therapeutic agent in regulating vessel wall remodeling following vascular injury.

The biology of estrogen-mediated repair of cardiovascular injury

Women appear to be protected from cardiovascular disease until the onset of menopause. Considerable evidence supports the atheroprotective effects of endogenous and supplemental estrogens. The beneficial effects of estrogens on lipid metabolism cannot wholly explain this phenomenon. Accumulating data suggest that estrogen may act at the cellular and molecular level to influence atherogenesis. The purpose of this review is to examine lipid-independent mechanisms of estrogen-mediated atheroprotection after cardiovascular injury.

Reactivity of cysteine residues in the protease from human immunodeficiency virus: identification of a surface-exposed region which affects enzyme function

The protease encoded by the human immunodeficiency virus (HIV) is essential for the processing of viral polyproteins encoded by the gag and pol genes into mature viral proteins. The 99-residue protease from HIV-1 contains two cysteine residues (Cys-67 and Cys-95), both of which are usually conserved in viruses isolated from patients. Despite this conservation, neither residue is required for enzymatic activity. Certain site-specific cysteine mutants of HIV-1 protease are catalytically active, and the protease from HIV-2 lacks both cysteines. Copper is a potent inhibitor of HIV-1 protease, but not of mutants lacking cysteine (A. R. Karlström and R. L. Levine, 1991, Proc. Natl. Acad. Sci. USA 88, 5552-5556). The addition of copper to the protease at pH 5.5 induced aggregation of the protein, providing a possible basis for the inhibitory action of copper. However, addition of both copper and dithiothreitol still led to inhibition of activity but did not cause aggregation. These findings led to a study of the reactivity of the cysteine residues to 5,5'-dithiobis-(2-nitrobenzoic acid) (Ellman's reagent), a sulfhydryl compound which reacts with the ionized form of cysteine residues. At pH 6.2 in 6 M guanidine, no derivatization of cysteine residues occurred, consistent with the typical pKa of cysteine expected for the denatured protein. However, in the same buffer without guanidine, the native protease reacted rapidly with concomitant loss of proteolytic activity. Peptic mapping demonstrated that both Cys-67 and Cys-95 were derivatized. A catalytically active fusion protein of protease with protein A domains was then studied with the expectation that access to Cys-95 would be hindered. This was confirmed, with only Cys-67 reacting rapidly with Ellman's reagent. Enzymatic activity was again lost, indicating that derivatization of the surface-accessible Cys-67 was sufficient to inactivate the enzyme. The reactivity and accessibility of these residues suggest an interesting approach for the development of protease inhibitors which are not directed to the substrate-binding site.