Decreased lung ischemia-reperfusion injury in rats after preoperative administration of cyclosporine and tacrolimus.

OBJECTIVES: Calcineurin inhibitors reduce experimental reperfusion injury in the liver, brain, heart, kidney, and small bowel. These studies were undertaken to determine whether these agents are similarly protective against lung ischemia-reperfusion injury. METHODS: Left lungs of male rats were rendered ischemic for 90 minutes and reperfused for as long as 4 hours. Treated animals received cyclosporine A (INN: ciclosporin; 1 or 5 mg/kg) or tacrolimus (0.2 mg/kg) 6 hours before ischemia, at reperfusion, or 2 hours after reperfusion. Injury was quantitated in terms of tissue polymorphonuclear leukocyte accumulation (myeloperoxidase content), vascular permeability (iodine 125-labeled bovine serum albumin extravasation), and bronchoalveolar lavage leukocyte content. Separate tissue samples were processed for nuclear protein and cytokine messenger RNA. RESULTS: Treatment with cyclosporine (5 mg/kg) or tacrolimus (0.2 mg/kg) 6 hours before reperfusion reduced lung vascular permeability by 54% and 56% relative to control animals (P <.03). The protective effects of cyclosporine and tacrolimus treatment before reperfusion correlated with 42% and 43% reductions in tissue polymorphonuclear leukocyte (myeloperoxidase) content (P <.008) and marked reductions in bronchoalveolar lavage leukocyte accumulation (P <.01). Administration of cyclosporine or tacrolimus at the time of reperfusion or 2 hours into the reperfusion period offered little or no protection. Animals treated before reperfusion also demonstrated marked reductions in nuclear factor kappaB activation and expression of proinflammatory cytokine messenger RNA. CONCLUSION: Cyclosporine and tacrolimus treatment before reperfusion was protective against lung ischemia-reperfusion injury in rats. The mechanism of these protective effects may involve the inhibition of nuclear factor kappaB, a central transcription factor mediating inflammatory injury. The decreased expression of cytokine messenger RNA indicates that both cyclosporine and tacrolimus may exert their protective effects at the pretranscriptional level.

Inhibition of the initial wave of NF-kappaB activity in rat muscle reduces ischemia/reperfusion injury.

Nuclear factor kappaB (NF-kappaB) is thought to play an important role in the expression of genes expressed in response to ischemia/reperfusion (I/R) injury. In this report, the activation of NF-kappaB in rat skeletal muscle during reperfusion following a 4-h ischemic period was studied. NF-kappaB activation displayed a biphasic pattern, showing peak activities from 30 min to 3 h postperfusion and 6 h to 16 h postperfusion, with a decline to baseline binding activity levels between 3 h and 6 h. Inhibition of NF-kappaB activation was investigated using proline dithiocarbamate (Pro-DTC). NF-kappaB binding activity during reperfusion was significantly reduced by intravenous administration of Pro-DTC. Additionally, Pro-DTC resulted in decreased muscle edema and neutrophil activity, with an increased percentage of muscle survival compared with vehicle controls. These results demonstrate that NF-kappaB is activated during reperfusion in a biphasic manner and that the regulation of the initial phase of NF-kappaB activation affords physiological protection against a severe ischemic stress. Selective inhibition of NF-kappaB during early reperfusion may therefore be a therapeutic intervention for I/R injury.

An essential role for NF-kappaB in the cardioadaptive response to ischemia.

BACKGROUND: Ischemic preconditioning (IP) is the phenomenon whereby brief episodes of ischemia protect the heart against a subsequent ischemic stress. We hypothesize that activation of the transcription factor NF-kappaB mediates IP. METHODS: Rabbits were randomly allocated to one of three groups: (1) 45 minutes of myocardial ischemia followed by 2 hours of reperfusion (I/R); (2) three cycles of 5-minute ischemia and 5 minutes of reperfusion followed by I/R (IP + I/R); or (3) IP in the presence of ProDTC, a specific NF-kappaB inhibitor, followed by I/R (IPProDTC + I/R). Infarct size, indices of regional contractility, and NF-kappaB activation were determined. RESULTS: In preconditioned rabbits (IP + I/R), infarct size was reduced 83% compared with both I/R alone and IPProDTC + I/R groups (p < 0.05). Throughout reperfusion, preconditioned myocardium showed enhanced regional contractile function compared with I/R and IPProDTC + I/R groups (p < 0.05). Gel shift analysis showed NF-kappaB activation with IP that was blocked by ProDTC. I/R and IPProDTC + I/R groups showed NF-kappaB activation with I/R that was absent in preconditioned animals. CONCLUSIONS: The cytoprotective effects induced by IP require activation of NF-kappaB.

Inhibition of the transcriptional activator protein nuclear factor kappaB prevents hemodynamic instability associated with the whole-body inflammatory response syndrome.

BACKGROUND: The transcription factor nuclear factor kappaB mediates the expression of a number of inflammatory genes involved in the whole-body inflammatory response to injury. We and others have found that dithiocarbamates specifically inhibit nuclear factor kappaB-mediated transcriptional activation in vitro. OBJECTIVE: We hypothesized that inhibition of nuclear factor kappaB with dithiocarbamate treatment in vivo would attenuate interleukin 1 alpha-mediated hypotension in a rabbit model of systemic inflammation. METHODS: New Zealand White rabbits were anesthetized and cannulated for continuous hemodynamic monitoring during 240 minutes. Rabbits were treated intravenously with either phosphate-buffered saline solution or 15 mg/kg of a dithiocarbamate, either pyrrolidine dithiocarbamate or proline dithiocarbamate, 60 minutes before the intravenous infusion of 5 micrograms/kg interleukin 1 alpha. Nuclear factor kappaB activation was evaluated by electrophoretic gel mobility shift assay of whole-tissue homogenates. RESULTS: Infusion of interleukin 1 alpha resulted in significant decreases in mean arterial pressure and systemic vascular resistance, both of which were prevented by treatment with dithiocarbamate. Pyrrolidine dithiocarbamate induced a significant metabolic acidosis, whereas proline dithiocarbamate did not. Nuclear factor kappaB-binding activity was increased within heart, lung, and liver tissue 4 hours after interleukin 1 alpha infusion. Treatment with dithiocarbamate resulted in decreased nuclear factor kappaB activation in lung and liver tissue with respect to that in control animals. CONCLUSIONS: These results demonstrate that nuclear factor kappaB is systemically activated during whole-body inflammation and that inhibition of nuclear factor kappaB in vivo attenuates interleukin 1 alpha-induced hypotension. Nuclear factor kappaB thus represents a potential therapeutic target in the treatment of hemodynamic instability associated with the whole-body inflammatory response.