Features of increased malignancy in eosinophilic clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) is the most common form of renal cancer. Due to inactivation of the von Hippel-Lindau tumour suppressor, the hypoxia-inducible transcription factors (HIFs) are constitutively activated in these tumours, resulting in a pseudo-hypoxic phenotype. The HIFs induce the expression of genes involved in angiogenesis and cell survival, but they also reset the cellular metabolism to protect cells from oxygen and nutrient deprivation. ccRCC tumours are highly vascularized and the cytoplasm of the cancer cells is filled with lipid droplets and glycogen, resulting in the histologically distinctive pale (clear) cytoplasm. Intratumoural heterogeneity may occur, and in some tumours, areas with granular, eosinophilic cytoplasm are found. Little is known regarding these traits and how they relate to the coexistent clear cell component, yet eosinophilic ccRCC is associated with higher grade and clinically more aggressive tumours. In this study, we have for the first time performed RNA sequencing comparing histologically verified clear cell and eosinophilic areas from ccRCC tissue, aiming to analyse the characteristics of these cell types. Findings from RNA sequencing were confirmed by immunohistochemical staining of biphasic ccRCC. We found that the eosinophilic phenotype displayed a higher proliferative drive and lower differentiation, and we confirmed a correlation to tumours of higher stage. We further identified mutations of the tumour suppressor p53 (TP53) exclusively in the eosinophilic ccRCC component, where mTORC1 activity was also elevated. Also, eosinophilic areas were less vascularized, yet harboured more abundant infiltrating immune cells. The cytoplasm of clear cell ccRCC cells was filled with lipids but had very low mitochondrial content, while the reverse was found in eosinophilic tissue. We herein suggest possible transcriptional mechanisms behind these phenomena. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Adenine-Induced Chronic Renal Failure in Rats: A Model of Chronic Renocardiac Syndrome with Left Ventricular Diastolic Dysfunction but Preserved Ejection Fraction.

BACKGROUND/AIMS: Cardiovascular disease is the major cause of death in patients with chronic kidney disease (CKD). Rats with adenine-induced chronic renal failure (ACRF) develop severe renal insufficiency and metabolic abnormalities that closely resemble those in patients with uremia. The aim of the present study was to determine left ventricular (LV) morphology and function in rats with ACRF. METHODS: Male Sprague-Dawley rats received either chow containing adenine or were pair-fed an identical diet without adenine (controls, C). After 9-13 weeks animals were anesthetized with isoflurane and cardiac function was assessed both by echocardiography and by LV catheterization. RESULTS: Rats with ACRF showed increases in serum creatinine (323±107 vs. 33±5 µM, P< 0.05), mean arterial pressure (115±6 vs. 106±7 mmHg, P< 0.05) and LV weight (3.4±0.3 vs. 2.5±0.2 mg/kg, P< 0.05) vs. controls. Rats with ACRF had reduced early diastolic tissue Doppler velocities in the LV, enlarged left atrial diameter (4.8±0.8 vs. 3.5±0.4 mm, P< 0.05) and elevated LV end-diastolic pressure (15±5 vs. 8±1 mmHg, P< 0.01). Cardiac output was increased in ACRF rats (211±66 vs. 149±24 ml/min, P< 0.05) and systolic function preserved. In the LV of ACRF rats there were statistically significant (P< 0.05) increases in cardiomyocyte diameter, proliferation and apoptosis, while there was no difference between groups in fibrosis. CONCLUSION: Rats with ACRF develop LV hypertrophy and diastolic dysfunction while systolic performance was preserved. There was an increased hypertrophy and apoptosis of cardiomyocytes in the LV of ACRF rats. The cardiac abnormalities in ACRF rats resemble those in patients with CKD in which heart failure with preserved ejection fraction is common. Hence, this experimental model is well suited for studying pathophysiological mechanisms in chronic renocardiac syndromes.

Rats with adenine-induced chronic renal failure develop low-renin, salt-sensitive hypertension and increased aortic stiffness.

Rats with adenine-induced chronic renal failure (A-CRF) develop metabolic and cardiovascular abnormalities resembling those in patients with chronic kidney disease. The aim of this study was to investigate the mechanisms of hypertension in this model and to assess aortic stiffness in vivo. Male Sprague-Dawley rats were equipped with radiotelemetry probes for arterial pressure recordings and received either chow containing adenine or normal control diet. At 7 to 11 wk after study start, blood pressure responses to high NaCl (4%) diet and different pharmacological interventions were analyzed. Aortic pulse wave velocity was measured under isoflurane anesthesia. Baseline 24-h mean arterial pressure (MAP) was 101 ± 10 and 119 ± 9 mmHg in controls and A-CRF animals, respectively (P < 0.01). After 5 days of a high-NaCl diet, MAP had increased by 24 ± 6 mmHg in A-CRF animals vs. 2 ± 1 mmHg in controls (P < 0.001). Candesartan (10 mg/kg by gavage) produced a more pronounced reduction of MAP in controls vs. A-CRF animals (-12 ± 3 vs. -5 ± 5 mmHg, P < 0.05). Aortic pulse wave velocity was elevated in A-CRF rats (5.10 ± 0.51 vs. 4.58 ± 0.17 m/s, P < 0.05). Plasma levels of creatinine were markedly elevated in A-CRF animals (259 ± 46 vs. 31 ± 2 µM, P < 0.001), whereas plasma renin activity was suppressed (0.6 ± 0.5 vs. 12.3 ± 7.3 µg·l(-1)·h(-1), P < 0.001). In conclusion, hypertension in A-CRF animals is characterized by low plasma renin activity and is aggravated by high-NaCl diet, suggesting a pathogenic role for sodium retention and hypervolemia probably secondary to renal insufficiency. Additionally, aortic stiffness was elevated in A-CRF animals as indicated by increased aortic pulse wave velocity.

Vascular function in rats with adenine-induced chronic renal failure.

The aim of the present study was to characterize the function of resistance arteries, and the aorta, in rats with adenine-induced chronic renal failure (A-CRF). Sprague-Dawley rats were randomized to chow with or without adenine supplementation. After 6-10 wk, mesenteric arteries and thoracic aortas were analyzed ex vivo by wire myography. Plasma creatinine concentrations were elevated twofold at 2 wk, and eight-fold at the time of death in A-CRF animals. Ambulatory systolic and diastolic blood pressures measured by radiotelemetry were significantly elevated in A-CRF animals from week 3 and onward. At death, A-CRF animals had anemia, hyperphosphatemia, hyperparathyroidism, and elevated plasma levels of asymmetric dimethylarginine and oxidative stress markers. There were no significant differences between groups in the sensitivity, or maximal response, to ACh, sodium nitroprusside (SNP), norepinephrine, or phenylephrine in either mesenteric arteries or aortas. However, in A-CRF animals, the rate of aortic relaxation was significantly reduced following washout of KCl (both in intact and endothelium-denuded aorta) and in response to ACh and SNP. Also the rate of contraction in response to KCl was significantly reduced in A-CRF animals both in mesenteric arteries and aortas. The media of A-CRF aortas was thickened and showed focal areas of fragmented elastic lamellae and disorganized smooth muscle cells. No vascular calcifications could be detected. These results indicate that severe renal failure for a duration of less than 10 wk in this model primarily affects the aorta and mainly slows the rate of relaxation.