Subthreshold doses of nebulized prostacyclin and rolipram synergistaically protect against lung ischemia-reperfusion

[Ischemia-reperfusion injury after lung transplantation]

Lung ischemia-reperfusion is characterized by diffuse alveolar damage arising from the first hours after transplantation. The first etiology of the primary graft dysfunction in lung is ischemia-reperfusion. It is burdened by an important morbi-mortality. Lung ischemia-reperfusion increases the oxidative stress, inactivates the sodium pump, increases the intracellular calcium, leads to cellular death and the liberation of pro-inflammatory mediators. Researches relative to the reduction of the lung ischemia-reperfusion injuries are numerous but few of them found a place in common clinical practice, because of an insufficient level of proofs. Ex vivolung evaluation is a suitable technique in order to evaluate therapeutics supposed to limit lung ischemia-reperfusion injuries.

Protective effects of phosphodiesterase-4-specific inhibitor rolipram on acute ischemia-reperfusion injury in rat kidney

OBJECTIVE

To investigate the effect of Rolipram, a phosphodiesterase-4-inhibitor, on renal ischemia-reperfusion injury (IRI) in rats.

METHODS

Thirty rats were divided into 5 different groups of 6 rats. Nothing was done to the control group. In the second group, the renal pedicle was clamped for 30 minutes. In the third group, 1 mg/kg of Rolipram was given by intraperitoneal injection 30 minutes before clamping. The fourth group received the same injection when the clamp was placed, as did the fifth group 30 minutes after the clamp was opened. Clamping time was set at 30 minutes. Twenty-four hours later, nephrectomy was performed in all the groups. Half of each kidney was examined histopathologically. Levels of biochemical agents, such as malondialdehyde, superoxide dismutase, and catalase, were measured in the other half.

RESULTS

The malondialdehyde (MDA) levels significantly decreased and reached control levels in the group in which Rolipram was administered 30 minutes after reperfusion (P = .07). The catalase and superoxide dismutase activities obtained from renal homogentisates of the ischemia groups were evaluated; there were striking increases in tissue levels of these 2 enzymes in the groups in which Rolipram was administered during ischemia and 30 minutes after ischemia (P < .001). Histopathologically, there was no significant difference in inflammation between the Rolipram-administrated groups compared with group 1 (control) and group 2 (IRI). Tubular necrosis and apoptosis was significantly lower in group 5 than the other groups, except group 1 (P < .001).

CONCLUSION

We suggest that in surgical procedures that can lead to renal IRI, the administration of Rolipram can decrease oxidative renal tissue damage and the severe deterioration of renal function.

Isoflurane Inhalation After Circulatory Arrest Protects Against Warm Ischemia Reperfusion Injury of the Lungs

BACKGROUND

Non-heart-beating donors are expected to ameliorate shortages of donors for organ transplantation. The issue of preventing warm ischemic injury after circulatory arrest must be investigated. In the current study, we investigated whether isoflurane inhalation during warm ischemia could attenuate ischemia reperfusion injury (IRI) of the lung.

METHODS

An isolated perfused rat lung model was used. The rats were allocated into four groups: the no ischemia group; the ischemia-1 minimum alveolar concentration (MAC) iso group (ventilation with air and 1.38% isoflurane); the Ischemia-3MAC iso group (ventilation with air and 4.2% isoflurane); and the Ischemia-no treatment group (ventilation with only air). Lungs were subjected to 50 min of ischemia at 37 degrees C. Physiological lung functions were measured after reperfusion in experiment one. Mitochondrial control ratio (RCR), cytochrome-c release from mitochondria, and caspase activities just after warm ischemia were measured in experiment two.

RESULTS

Pulmonary functions in the Ischemia-1MAC iso group were significantly greater than those in the Ischemia-no treatment group for experiment one. There were no dose-dependent effects between 1MAC and 3MAC isoflurane. In experiment two, RCR in the Ischemia-1MAC iso group was significantly greater than that in the Ischemia-no treatment group. Cytochrome-c release and caspase-9 activity in the Ischemia-1MAC iso group were significantly decreased compared to those in the Ischemia-no treatment group.

CONCLUSIONS

Isoflurane inhalation attenuates warm IRI with the protection of mitochondria. Our results suggest that isoflurane inhalation after circulatory arrest can be a simple and effective method to protect the lung against warm ischemia.

PDE4 inhibitors as new anti-inflammatory drugs: effects on cell trafficking and cell adhesion molecules expression

Phosphodiesterase 4 (PDE4) is a major cyclic AMP-hydrolyzing enzyme in inflammatory and immunomodulatory cells. The wide range of inflammatory mechanisms under control by PDE4 points to this isoenzyme as an attractive target for new anti-inflammatory drugs. Selective inhibitors of PDE4 have demonstrated a broad spectrum of anti-inflammatory activities including the inhibition of cellular trafficking and microvascular leakage, cytokine and chemokine release from inflammatory cells, reactive oxygen species production, and cell adhesion molecule expression in a variety of in vitro and in vivo experimental models. The initially detected side effects, mainly nausea and emesis, appear at least partially overcome by the 'second generation' PDE4 inhibitors, some of which like roflumilast and cilomilast are in the later stages of clinical development for treatment of chronic obstructive pulmonary disease. These new drugs may also offer opportunities for treatment of other inflammatory diseases.