A novel model of vascular complications in type I diabetes:new mechanisms and treatments – IN2DN

Every month measurement of glycemia, tryglyceride and cholesterol.
Measurement of water consumption, diuresis and evaluation of albuminuria and creatinemia from mouse put in metabolic cage.
Evaluation of the glomerular fitration rate by using Inulin-FITC
Evaluation of the foot process effacement and glomerular basal membrane thickness by electron microscopy.
Evaluation of macrophage infiltration and accumulation of collagen type III in the tubulointerstial space by immunohistochemistry

We observe as soon as the first month of life a very high hyperglycemia in the two diabetic strains (Ins2Akita/+ et Ins2Akita/+Ldlr-/-) which is associated to an increase water intake and diuresis. As expected the ldlr-/- mice have increased triglyceridemia and cholesterolemia and the diabetic state of the Ins2Akita/+Ldlr-/- has no effect on these two parameters.
Renal function increase as soon as the 3rd month and start to decrease at the 4th month.
We observe a glomerular hypertrophy at 2 month of age in the (Ins2Akita/+ et Ins2Akita/+Ldlr-/-) and vacuolisation and glomerulosclerosis in the (Ins2Akita/+Ldlr-/-) . The diabetic and atherosclerotic mice exhibit at two month of age similar structural alteration than the diabetic animals at 4 month of life.
Ins2Akita/+Ldlr-/- mice are very sick and most of them die before 6 month of age
We observed a foot process effacement (FPE) in the diabetic mice at the 3rd month of life: Ins2Akita/+ 675±12nm, Ins2Akita/+Ldlr-/- 766±42nm, vs wild type 442±18nm, and a thickening of the glomerular basal membrane Ins2Akita/+215±42nm,Ins2Akita/+Ldlr-/- 280±40nm vs wild type 200± 25 nm). These two parameters sign the first phase of diabetic nephropathy.

To achieve the next steps of the project, because of the frailty of the Ins2Akita/+Ldlr-/- we plan to do the pharmacological treatment with the bradykinin B1 receptor antagonist and the ACE-inhibitor ramipril in 2+3 month old mice and analyse the glomerular and aorta proteome after 2 months treatment

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The prevalence of diabetes continues to increase worldwide and premature mortality in diabetic patients largely is related to macro- and microvascular complications. One of these major microvascular complications is diabetic nephropathy (DN) which significantly amplifies mortality in the diabetic population. Despite efficient therapies to control glycaemia and blood pressure, still 25-30% of the patients develop DN and macrovascular complications. There is thus ample space to improve treatment of these complications but this needs better understanding of the mechanisms involved. We believe that one of the major causes of this lack of knowledge is the absence of an animal model cumulating both micro- and macrovascular lesions. Therefore, by using a new animal model of type I diabetes (T1D) mimicking human vascular complications in diabetes: DN as a prototype microvascular lesion and atherosclerosis, the current project aims to better understand the development and progression of DN by the in-depth characterisation of this new animal model. Using this model we will focus on the renal lesions to:
i) Identify new pathophysiological mechanisms in the progression of DN using integrated –omics approaches (both transcriptomics and proteomics) on microdissected renal vascular structures. This will lead to the clear-cut propositions of new mechanisms/pathways involved in the development of renal microvascular lesions in T1D and allows determining which signalling pathways may be targets to be blocked to work in synergy with renin-angiotensin system (RAS) inhibition.
ii) Determine the strongly anticipated synergy of an orally active antifibrotic compound (bradykinin B1-receptor antagonist) and RAS inhibition in preventing DN in T1D. Validation of this concept can be rapidly transferred to the clinic as RASi are routinely used in the clinic and orally available B1 receptor antagonists are in early phase clinical trials for other indications.
iii) Identify urinary biomarkers predictive of the progression of vascular lesions of T1D in both mice and men allowing the non-invasive evaluation of the efficacy of drug treatment enabling pre-clinical use of this novel model.
Overall with this project we anticipate to significantly contribute to the understanding of the mechanism of T1D nephropathy using a novel mouse model where both macro- and microvascular complications are present, propose a novel two-drugs synergistic treatment for these complications and transform this mouse model into a pre-clinical tool for efficient testing and discovery of new drugs that will reduce the risk of developing vascular complications diabetes which is the main cause of premature mortality in these patients.