Ultrastructural Pathology of Rat Lung Injury Induced by Ischemic Acute Kidney Injury

Ischemic acute kidney injury (AKI) is a common complication during inpatient hospitalization, and often induces acute lung injury (ALI). A lot of studies have concentrated on the relevance between AKI and ALI, but the underlying mechanisms of AKI- associated ALI have remained unclear until now. One reason is that evidence of the ultrastructural pathology of AKI-associated ALI has been scarce and needed to be accumulated. The aims of present study are to observe ultrastructural changes, and to reveal leukocyte trafficking of ALI induced by ischemic AKI in rats. For this purpose light microscopy (LM) and electron microscopy (EM), as well as morphometric analysis, were employed in present study. LM observations revealed distinct regions of collapsed alveoli, hemorrhage in alveoli, and interstitial edema in AKI-induced ALI. EM examinations provided facts that alveolar epithelial cells, including type I and type II cells, were necrotic, and endothelia cells undergoing apoptosis as well as interstitial cells undergoing necroptosis were noted in AKI lungs. In addition, shrinkage and decreased or disappeared lamellar bodies were evident in alveolar type II cell of AKI rat lungs. Leukocyte numerical density on area (N-A) in AKI lungs was significantly more than that in sham lungs. Based on the morphological criteria from EM examinations and morphometric analysis, a conclusion was that necrosis, including necroptosis, and apoptosis were involved in damaged lung induced by AKI. And inflammation also contributed to acute lung injury of rats with AKI.