Saskatoon berry supplementation prevents cardiac remodeling without improving renal disease in an animal model of reno-cardiac syndrome.

Saskatoon berry (SKB) may have the potential to counter reno-cardiac syndrome owing to its antioxidant capacity. Here, we investigated the renal and cardiovascular effects of SKB-enriched diet in a rat model of reno-cardiac disease. Two groups of wild-type rats (+/+) and two groups of Hannover Sprague-Dawley (Han:SPRD-Cy/+) rats were given either regular diet or SKB diet (10% w/w total diet) for 8 weeks. Body weight, kidney weight, kidney water content, and left ventricle (LV) weight were measured. Blood pressure (BP) was measured by the tail-cuff method. Echocardiography was performed to assess cardiac structure and function. Serum creatinine and malondialdehyde (MDA) were also measured. Han:SPRD-Cy/+ rats had significantly higher kidney weight, kidney water content, LV weight, BP, and creatinine compared with wild-type rats (+/+). The SKB diet supplementation did not reduce kidney weight, kidney water content, BP, and LV weight in Han:SPRD-Cy/+ rats. The SKB diet also resulted in higher systolic BP in Han:SPRD-Cy/+rats. Han:SPRD-Cy/+rats showed cardiac structural remodeling (higher LV wall thickness) without any cardiac functional abnormalities. Han:SPRD-Cy/+ rats also had significantly higher creatinine whereas the concentration of MDA was not different. The SKB diet supplementation reduced cardiac remodeling and the concentration of MDA without altering the concentration of creatinine in Han:SPRD-Cy/+ rats. In conclusion, Han:SPRD-Cy/+ rats developed significant renal disease, high BP, and cardiac remodeling by 8 weeks without cardiac functional impairment. The SKB diet may be useful in preventing cardiac remodeling and oxidative stress in Han:SPRD-Cy/+rats. PRACTICAL APPLICATIONS: Saskatoon berry (SKB) is widely consumed as fresh fruit or processed fruit items and has significant commercial value. It may offer health benefits due to the presence of bioactives such as anthocyanins. SKB has very good culinary flavors, and it is an economically viable fruit crop in many parts of the world. The disease-modifying benefits of SKB are mainly ascribed to the antioxidant nature of its bioactive content. Polycystic kidney disease is a serious condition that can lead to renal and cardiac abnormalities. Here, we showed that SKB supplementation was able to mitigate cardiac remodeling and lower the level of a marker of oxidative stress in an animal model of reno-cardiac syndrome. Our study suggests that SKB possesses beneficial cardioprotective properties. Further evidence from human studies may help in increasing the consumption of SKB as a functional food.

Immunohistochemistry of Kidney a-SMA, Collagen 1, and Collagen 3, in A Novel Mouse Model of Reno-cardiac Syndrome.

Cardiorenal syndrome defines a synergistic pathology of the heart and kidneys where failure of one organ causes failure in the other. The incidence of cardiovascular mortality caused by this syndrome, is 20 fold higher in the end stage renal disease (ESRD) population compared to the population as a whole thus necessitating the need for improved therapeutic strategies to combat reno-cardiac pathologies. Murine in vivo models play a major role in such research permitting precise genetic modification thus reducing miscellany, however presently there is no steadfast model of reno-cardiac syndrome in the most common genetically modified mouse strain, the C57BL/6 mouse. In this study we have modified an established model of chronic renal disease using adenine diet and extended the associated pathology achieving chronic renal failure and consequent reno-cardiac syndrome in the C57BL/6 mouse. Eight week-old male C57BL/6 mice were acclimatized for 7 days before administration of a 0.15% adenine diet or control diet for 20 weeks after which the experiment was terminated and blood, urine and organs were collected and analyzed biochemically and by immunohistochemistry. Administration of 0.15% adenine diet caused progressive renal failure resulting in a reno-cardiac syndrome confirmed by a significantly increased heart to body weight ratio (P < 0.0001). Blood biochemistry showed that adenine fed mice had significantly increased serum creatinine, urea (P < 0.0001), and a significantly reduced glomerular filtration rate (P < 0.05), while immunohistochemistry of the kidneys for α-SMA, collagen 1 and collagen 3 showed severe fibrosis. We present a novel regimen of adenine diet which induces both chronic kidney disease and reno-cardiac syndrome in the C57BL/6 mouse strain. The non-surgical nature of this model makes it highly reproducible compared to other models currently available.

A novel model of reno-cardiac syndrome in the C57BL/ 6 mouse strain.

BACKGROUND: The end stage renal disease population has a 20 fold higher incidence of cardiovascular mortality compared to the overall population. The development of reno-cardiac syndrome in these patients will result in cardiovascular events to be the cause of 50% of fatalities. There is therefore a need to research improved therapeutic strategies to combat renal cardiac pathologies. Murine in vivo models contribute greatly to such research allowing for specific genetic modification and reduced miscellany, however there is currently no reliable model of reno-cardiac syndrome in the most common genetically modified mouse strain, the C57BL/6. In this study we have manipulated an established model of chronic renal disease using adenine infused diet and prolonged the course of its pathology achieving chronic renal failure and subsequent reno-cardiac syndrome in the C57BL/6 mouse. METHODS: Eight week-old male C57BL/ 6 mice were acclimatised for 7 days before administration of a 0.15% adenine diet or control diet for 20 weeks. Cardiac function was assessed in mice at week 20 by echocardiography. At experiment termination blood and urine samples were analysed biochemically and organ dysfunction/injury was determined using immunoblotting and immunohistochemistry. RESULTS: Administration of 0.15% adenine diet caused progressive renal failure resulting in reno-cardiac syndrome. At endpoint uraemia was confirmed by blood biochemistry which in the adenine fed mice showed significant increases in serum creatinine, urea, calcium (P < 0.0001) potassium (P < 0.05), and a significantly reduced glomerular filtration rate (P < 0.05). Reno-cardiac syndrome was confirmed by a significantly increased heart to body weight ratio (P < 0.0001) and echocardiography which showed significant reductions in percentage of ejection fraction, fractional shortening, fractional area change, (P < 0.0001) and an increase in left ventricular end diastolic volume (P < 0.05). Immunoblotting of kidney and heart tissue showed increased apoptosis (caspase 3) and fibrosis (fibronectin) and increases in the cardiac levels of phosphorylated Akt, and renal total Akt. Immunohistochemistry for α-SMA, collagen 1 and collagen 3 further confirmed fibrosis. CONCLUSIONS: We present a novel regimen of adenine diet which induces both chronic kidney disease and reno-cardiac syndrome in the C57/BL6 mouse strain. The non-surgical nature of this model makes it highly reproducible compared to other models currently available.

Soy Protein Alleviates Hypertension and Fish Oil Improves Diastolic Heart Function in the Han:SPRD-Cy Rat Model of Cystic Kidney Disease.

Abnormalities in cardiac structure and function are very common among people with chronic kidney disease, in whom cardiovascular disease is the major cause of death. Dietary soy protein and fish oil reduce kidney disease progression in the Han:SPRD-Cy model of cystic renal disease. However, the effects of these dietary interventions in preventing alterations in cardiac structure and function due to kidney disease (reno-cardiac syndrome) in a cystic kidney disease model are not known. Therefore, weanling Han:SPRD-Cy diseased (Cy/+) and normal (+/+) rats were given diets containing either casein or soy protein, and either soy or fish oil in a three-way design for 8 weeks. Diseased rats had larger hearts, augmented left ventricular mass, and higher systolic and mean arterial blood pressure compared to the normal rats. Assessment of cardiac function using two-dimensional guided M-mode and pulse-wave Doppler echocardiography revealed that isovolumic relaxation time was prolonged in the diseased compared to normal rats, reflecting a diastolic heart dysfunction, and fish oil prevented this elevation. Soy protein resulted in a small improvement in systolic and mean arterial pressure but did not improve diastolic heart function, while fish oil prevented diastolic heart dysfunction in this model of cystic kidney disease.

The Impact of Donor and Recipient Renal Dysfunction on Cardiac Allograft Survival: Insights Into Reno-Cardiac Interactions.

BACKGROUND: Renal dysfunction (RD) is a potent risk factor for death in patients with cardiovascular disease. This relationship may be causal; experimentally induced RD produces findings such as myocardial necrosis and apoptosis in animals. Cardiac transplantation provides an opportunity to investigate this hypothesis in humans. METHODS AND RESULTS: Cardiac transplantations from the United Network for Organ Sharing registry were studied (n = 23,056). RD was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m(2). RD was present in 17.9% of donors and 39.4% of recipients. Unlike multiple donor characteristics, such as older age, hypertension, or diabetes, donor RD was not associated with recipient death or retransplantation (age-adjusted hazard ratio [HR] = 1.00, 95% confidence interval [CI] 0.94-1.07, P = .92). Moreover, in recipients with RD the highest risk for death or retransplantation occurred immediately posttransplant (0-30 day HR = 1.8, 95% CI 1.54-2.02, P < .001) with subsequent attenuation of the risk over time (30-365 day HR = 0.92, 95% CI 0.77-1.09, P = .33). CONCLUSIONS: The risk for adverse recipient outcomes associated with RD does not appear to be transferrable from donor to recipient via the cardiac allograft, and the risk associated with recipient RD is greatest immediately following transplant. These observations suggest that the risk for adverse outcomes associated with RD is likely primarily driven by nonmyocardial factors.