Diethylmaleate, a pro-oxidant, attenuates experimental ischaemia-reperfusion-induced lung injury

Effects of thermal preconditioning on the ischemia-reperfusion-induced acute lung injury in minipigs

Lung ischemia-reperfusion (I/R) injury plays an important role in many clinical issues. A series of mechanisms after I/R has been uncovered after numerous related studies. Organ preconditioning (PC) is a process whereby a brief antecedent event, such as transient ischemia, oxidative stress, temperature change, or drug administration, bestows on an organ an early or delayed tolerance to further insults by the same or different stressors. In this study, we want to uncover the optimal thermal PC patterns that cause maximal early or delayed protective effect on the subsequent pulmonary I/R with the use of miniature pig model. Twenty-eight 15- to 20-kg weight Lanyu miniature pigs are used and divided into four groups (seven sham operation control [NC], seven PC only [PC], seven I/R [I/R], and seven PC followed by I/R [PC + I/R]). The PC was performed with the animals being anesthetized and, using an alternative hyperthermic (40 degrees C) and normothermic moist air to ventilate their lungs for 15 min, respectively, for 2 cycles, followed by I/R, which consists of 90 min of blocking the perfusion and ventilation of the left lung followed by 240 min of reperfusion. Control animals had a thoracotomy with hilar dissection only. Indicators of lung injury included hemodynamic parameters, blood gas analysis, histopathological (lung pathology, wet/dry weight ratio, myeloperoxidase assay), and molecular biological profiles (interleukin-1beta [IL-1beta], IL-6, tumor necrosis factor-alpha by enzyme-linked immunosorbent assay analysis). Lung tissue heat shock protein 70 (HSP-70) expression was also detected by Western blotting. This model of lung I/R induced significant lung injury with pulmonary hypertension, increased pulmonary vascular resistance, and pulmonary venous hypoxemia at the ischemia side, increased pulmonary tissue injury score and neutrophil infiltration, increased wet/dry ratio, myeloperoxidase assay, tumor necrosis factor-alpha, IL-1beta, and IL-6 assay. This type of thermal PC would not injure the lung parenchyma or tracheal epithelium. Moreover, it could attenuate the I/R-related lung injury, with some of these parameters improved significantly. Increased expression of HSP-70 was also found in the group of PC plus I/R than the I/R only. Less prominent and transient increase in expression of HSP-70 was found in the PC group. We concluded that the intratracheal thermal PC can effectively attenuate I/R-induced lung injury through various mechanisms, including the decrease of various proinflammatory cytokines. The mechanism of its protective effect might be related to the increased expression of HSP-70.

The effects of erdosteine on lung injury induced by the ischemia-reperfusion of the hind-limbs in rats

BACKGROUND

[corrected] The goal of this experimental study was to investigate whether erdosteine has a protective effect against lung injury as a remote organ after hind-limb ischemia-reperfusion (I/R).

MATERIALS AND METHODS

The rats were divided into three groups: control, I/R, and I/R + erdosteine. After the experimental procedure, nitric oxide (NO) levels, myeloperoxidase (MPO), adenosine deaminase (ADA), and the activities of xanthine oxidase (XO) were determined on the lung tissue. The levels of NO and activities of MPO were also measured on the bronchial alveolar lavage (BAL). In addition, the lung tissue was examined by histopathology.

RESULTS

The lung tissue ADA and XO activities were increased in the I/R group compared with the control group (P < 0.05). In the I/R group, the levels of NO were higher than the control group (P < 0.05), whereas the erdosteine treatment did not alter the NO levels (P < 0.05). The MPO activities increased after I/R in the I/R group compared to both control and I/R + erdosteine group (P < 0.05). The activity of MPO increased in the IR group in comparison with the control group in BAL (P < 0.05). The activity of MPO in the I/R + erdosteine group was significantly lower than the I/R group in BAL (P < 0.05). NO levels increased in all I/R groups compared to control group in BAL (P < 0.05). However, treatment of erdosteine significantly decreased NO levels compared to I/R group (P < 0.05). The animals of the I/R group had total destruction of normal alveolar structure with the intense presence of infiltrating neutrophils and mononuclear phagocytes in histopathological examination. The rat lung exhibited mild degrees of destruction in the erdosteine group.

CONCLUSIONS

As a result, erdosteine may be a protective effect for lung injury, decreasing oxidative stress and neutrophil accumulation after hind-limb I/R in rats.

Organ preconditioning: the past, current status, and related lung studies

Preconditioning (PC) has emerged as a powerful method for experimentally and clinically attenuating various types of organ injuries. In this paper related clinical and basic research issues on organ preconditioning issues were systemically reviewed. Since lung injuries, including ischemia-reperfusion and others, play important roles in many clinical results, including thromboembolism, trauma, thermal injury, hypovolemic and endotoxin shock, reimplantation response after organ transplantation, and many respiratory diseases in critical care. It is of interest to uncover methods, including the PCs, to protect the lung from the above injuries. However, related studies on pulmonary PC are relatively rare and still being developed, so we will review previous literature on experimental and clinical studies on pulmonary PC in the following paragraphs.