BackgroundAtherosclerotic cardiovascular disease is prevalent among patients with chronic kidney disease (CKD). In this study, we initially aimed to test whether vascular calcification associated with CKD can worsen atherosclerosis. However, a paradoxical finding emerged from attempting to test this hypothesis in a mouse model of adenine-induced CKD.MethodsWe combined adenine-induced CKD and diet-induced atherosclerosis in mice with a mutation in the low-density lipoprotein receptor gene. In the first study, mice were co-treated with 0.2% adenine in a western diet for 8 weeks to induce CKD and atherosclerosis simultaneously. In the second study, mice were pre-treated with adenine in a regular diet for 8 weeks, followed by a western diet for another 8 weeks.ResultsCo-treatment with adenine and a western diet resulted in a reduction of plasma triglycerides and cholesterol, liver lipid contents, and atherosclerosis in co-treated mice when compared with the western-only group, despite a fully penetrant CKD phenotype developed in response to adenine. In the two-step model, renal tubulointerstitial damage and polyuria persisted after the discontinuation of adenine in the adenine-pre-treated mice. The mice, however, had similar plasma triglycerides, cholesterol, liver lipid contents, and aortic root atherosclerosis after being fed a western diet, irrespective of adenine pre-treatment. Unexpectedly, adenine pre-treated mice consumed twice the calories from the diet as those not pre-treated without showing an increase in body weight.ConclusionThe adenine-induced CKD model does not recapitulate accelerated atherosclerosis, limiting its use in pre-clinical studies. The results indicate that excessive adenine intake impacts lipid metabolism.

Introduction: Patients with chronic kidney disease (CKD) experience significant cardiovascular morbidity and mortality. Vascular calcification is a hallmark of CKD and a strong predictor of atherosclerotic cardiovascular disease. Hypothesis: We hypothesize that CKD-induced vascular calcification potentiates atherosclerosis. Methods: First, wished to conduct a pilot study to confirm that a co-treatment of the low-density protein receptor mutant mice (Ldlr whc ) with a 0.2% adenine in a western diet will produce accelerated atherosclerosis, consistent with a well-known phenotype in the 5/6 nephrectomy model on an ApoE or Ldlr knockout background. Then we developed a two-step non-surgical mouse model in which the induction of calcification by a 0.2% adenine treatment was followed by western diet-induced hyperlipidemia. Results: Contrary to expected, the adenine and western diet (W+A) co-treatment resulted in a striking reduction of plasma triglycerides (TG), aortic root atherosclerosis, and liver lipids despite a fully penetrant CKD phenotype with tubulointerstitial damage, increased blood urea nitrogen, hyperphosphatemia, polyuria, vascular calcification, and osteoporosis. The two-step induction of CKD and atherosclerosis demonstrated partially normalized but reduced plasma triglycerides and liver lipid content, polyurea, and polydipsia in CKD mice, and there was no difference in atherosclerotic burden or plaque calcification between the groups. Interestingly we observed an increase in food and calorie intake and 24-hour glucose excretion in the urine in the pre-treated group compared with mice on a western diet without pre-treatment, while plasma glucose levels were not different between the groups. Conclusion: The paradoxical lack of dyslipidemia in mice treated with adenine provides an insight into the potential effects of tubulointerstitial kidney disease and nephrogenic diabetes incipits on lipid metabolism and atherosclerosis. 1