Histopathological Changes in the Kidney following Congestive Heart Failure by Volume Overload in Rats

Background. This study investigated histopathological changes and apoptotic factors that may be involved in the renal damage caused by congestive heart failure in a rat model of infrarenal aortocaval fistula (ACF). Methods. Heart failure was induced using a modified approach of ACF in male Wistar rats. Sham-operated controls and ACF rats were characterized by their morphometric and hemodynamic parameters and investigated for their histopathological, ultrastructural, and apoptotic factor changes in the kidney. Results. ACF- induced heart failure is associated with histopathological signs of congestion and glomerular and tubular atrophy, as well as nuclear and cellular degeneration in the kidney. In parallel, overexpression of proapoptotic Bax protein, release of cytochrome C from the outer mitochondrial membrane into cell cytoplasm, and nuclear transfer of activated caspase 3 indicate apoptotic events. This was confirmed by electron microscopic findings of apoptotic signs in the kidney such as swollen mitochondria and degenerated nuclei in renal tubular cells. Conclusions. This study provides morphological evidence of renal injury during heart failure which may be due to caspase-mediated apoptosis via overexpression of proapoptotic Bax protein, subsequent mitochondrial cytochrome C release, and final nuclear transfer of activated caspase 3, supporting the notion of a cardiorenal syndrome

Pathological alterations in liver injury following congestive heart failure induced by volume overload in rats

Heart failure has emerged as a disease with significant public health implications. Following progression of heart failure, heart and liver dysfunction are frequently combined in hospitalized patients leading to increased morbidity and mortality. Here, we investigated the underlying pathological alterations in liver injury following heart failure. Heart failure was induced using a modified infrarenal aortocaval fistula (ACF) in male Wistar rats. Sham operated and ACF rats were compared for their morphometric and hemodynamic data, for histopathological and ultrastructural changes in the liver as well as differences in the expression of apoptotic factors. ACF-induced heart failure is associated with light microscopic signs of apparent congestion of blood vessels, increased apoptosis and breakdown of hepatocytes and inflammatory cell inifltration were observed. The glycogen content depletion associated with the increased hepatic fibrosis, lipid globule formation was observed in ACF rats. Moreover, cytoplasmic organelles are no longer distinguishable in many ACF hepatocytes with degenerated fragmented rough endoplasmic reticulum, shrunken mitochondria and heavy cytoplasm vacuolization. ACF is associated with the upregulation of the hepatic TUNEL-positive cells and proapoptotic factor Bax protein concomitant with the mitochondrial leakage of cytochrome C into the cell cytoplasm and the transfer of activated caspase 3 from the cytoplasm into the nucleus indicating intrinsic apoptotic events. Taken together, the results demonstrate that ACF-induced congestive heart failure causes liver injury which results in hepatocellular apoptotic cell death mediated by the intrinsic pathway of mitochondrial cytochrome C leakage and subsequent transfer of activated caspase 3 into to the nucleus to initiate overt DNA fragmentation and cell death

Heart and lung morphological changes following ACF-induced congestive heart failure.

<p>Increased heart and lung weight indices (<b>A, B, D</b>) but not body weight (<b>C</b>) following ACF-induced congestive heart failure. Note, that heart and lung weight indices were significantly increased at 28 days of ACF rats (n = 10) compared to those of sham operated controls (n = 5) (heart index: ACF 6.5±1.6 versus Controls 3.9±0.2; lung index: ACF 6.9±1.4 versus Controls 3.8±0.3; p<0.01, Student t-test) (<b>D</b>). Data show means ± SD.</p

Light microscopic photographs of representative haematoxylin-eosin and toluidine blue stained liver sections.

<p><b>A</b>) Note normal lobular structure with hepatocytes having prominent rounded nuclei. <b>B-D</b>) Liver sections of ACF rats show pyknotic nuclei (PN), cytoplasmic vacuolization, sinusoidal dilation (SD), leukocyte infiltration (Leu) massive breakdown of hepatocytes (*), and congestive blood vessels (double arrows) as well as a crescent-shaped condensation of nuclear chromatin (arrow). <b>E</b>) Semithin liver sections of control rats were stained in 1% toluidine blue showing normal branching and anastomosing hepatocyte cords separated by hepatic blood sinusoids. Note, hepatocytes contain prominent rounded nuclei (N). <b>F</b>) Semithin liver sections of ACF rats show hepatocytes with large vacuoles (arrow head) in the periportal area, heterogeneous parenchyma, which consists of dark and compact hepatocytes flanked by ballooned cells (also called apoptotic cells) (arrow) with nuclear degeneration (ND). Bars = 20 μm.</p

Light microscopic photographs of representative pan-leukocyte marker CD45 immunohistochemistry as well as Periodic acid-Schiff (PAS) and Oil Red O staining of liver sections.

<p><b>A-C</b>) show leukocyte infiltrations as detected with pan-leukocyte marker CD45 (green fluorescence) with DAPI-counterstained nuclei (blue fluorescence) within the liver sinusoids. Quantification of CD45⁺ leukocyte positive cells/200 mm² showed significantly more leukocytes in ACF rats (34.3±5.6) compared to controls (2.5±0.3)(p<0.05, Student t-test). <b>D-F</b>) show that the glycogen granules of the hepatic cells as examined in PAS-stained sections of liver showed a significant decrease in glycogen granules in ACF rats (78.8±3.8) compared to control (100±2.8)(p<0.05, Student t-test). <b>G-I</b>) Representative Oil Red O stain highlighting fat globules in a frozen section of the liver revealed the presence of large (macrovesicular) fat globules only in ACF rats (n = 5) compared to controls (n = 5)(PAS-optical density ACF: 198.3±4.9% versus controls: 100±12.4%) p<0.05, Student t-test). Bars = 20 μm. Data show means ± SD.</p