PURPOSE:Reperfusion injury is an important pathologic feature of several clinically significant lung conditions such as sepsis, shock, pulmonary embolism and lung transplantation. We have recently reported anti-apoptotic properties of dietary flaxseed against lung ischemia/reperfusion (I/R) injury. Our aim was to further investigate if this inhibitory effect is the result of attenuation of caspase enzymes known to be involved in apoptosis.
METHODS:We established a warm I/R injury model of the lung in C57BL/6J mice. Mice were fed either 0% flaxseed diet (control group, n=6) or 10% flaxseed diet (treatment group, n=9) for two weeks to achieve peak flaxseed lignin levels in the blood. After induction of anesthesia and tracheostomy, a small animal ventilator was used to maintain adequate minute ventilation. A left thoracotomy was performed and a microvascular clamp was used to occlude the left pulmonary hilum. After 60 minutes, the clamp was removed and the left lung was reperfused for 3 hours. Subsequently, the animals were euthanized and lung specimens preserved for tissue processing. A multi-PCR technique was used to analyze differential mRNA expression levels in lung homogenates of various caspase enzymes involved in apoptosis such as Caspase-1, Caspase-2, Caspase-3, Caspase-8, Caspase-9 and Apoptosis activating factor 1 (ApaF1).
RESULTS:The multi-PCR results show a decrease in the expression of caspase enzymes involved in apoptosis in the treatment group as compared to the control group (18s RNA serves as internal control). In particular, this inhibitory effect of flaxseed was more pronounced on the expression of Caspase-1, Caspase-9 and ApaF1.
CONCLUSION:Reperfusion injury is known to cause organ dysfunction in part by apoptosis. This study further elaborates our observations by suggesting that flaxseed modulates the expression of caspase enzymes involved in apoptosis.
CLINICAL IMPLICATIONS:Organ dysfunction caused by apoptosis is a clinically important problem. Although the apoptotic pathway is complex, we postulate a therapeutic role for caspase enzyme inhibitors in the prevention of lung reperfusion injury caused by apoptosis.
DISCLOSURE:M. Jawad Latif, None.