Abstract:

Objective To investigate the characteristics of lung tissue injury and expression of aquaporins(AQP) after acute kidney injury in mice. Methods Seventy-five male C57BL/6 mice were randomly divided into sham operation group (n=25) and acute kidney injury group (n=50), and acute kidney injury models were established in acute kidney injury group by ischemia-reperfusion (I/R group, n=25) and bilateral nephrectomy (BNx group, n=25). Mice were sacrificed and lung tissues were collected 0 h, 2 h, 4 h, 6 h and 24 h after model establishment. Pathological changes of lung tissues were observed by light microscopy with HE staining, leukocyte infiltration was counted, ratio of lung wet weight to dry weight (W/D) was calculated, and real-time quantitative polymerase chain reaction (Real-Time PCR) and immunohistochemical staining were employed to detect the expression of AQP-1 and AQP-5 mRNA and protein in lung tissues. Results Inflammatory cell infiltration in lung tissues, alveolar hemorrhage and interstitial edema developed 2 h and 4 h after model establishment in I/R group and BNx group, respectively. The numbers of leukocytes in lung tissues 4 h, 6 h and 24 h after model establishment in BNx group and 2 h, 4 h, 6 h and 24 h after model establishment in I/R group were significantly larger than those in sham operation group (P<0.05). W/D in BNx group and I/R group were significantly higher than those in sham operation group 4 h, 6 h and 24 h after model establishment (P<0.05). The expression of AQP-1 mRNA and protein in lung tissues in BNx group and I/R group was not significantly different from that in sham operation group at each time point (P>0.05). The expression of AQP-5 mRNA and protein in lung tissues in BNx group was significantly lower than that in sham operation group at the time points of 2 h, 4 h, 6 h and 24 h (P<0.05), and the expression of AQP-5 mRNA and protein in lung tissues in I/R group was significantly lower than that in sham operation group at the time points of 6 h and 24 h (P<0.05). Conclusion Lung edema is the typical characteristics of acute lung injury after acute kidney injury, which may be related to the inflammatory reaction and expression of AQP-5.

Key words: acute kidney injury, acute lung injury, aquaporins, inflammation