direct-drug-delivery-to-kidney-via-the-renal-artery

Direct Drug Delivery to Kidney via the Renal Artery

There is a need for directed injections to enable increased and specific renal exposure for efficient evaluation of drug targets in the renal research ...

BioPharmaceuticals R&D

Type 2 diabetes is associated with macro- and microvascular complications in man. Microvascular dysfunction affects both cardiac and renal function and is now recognized as a main driver of cardiovascular mortality and morbidity. However, progression of microvascular dysfunction in experimental models is often obscured by macrovascular pathology and consequently demanding to study. The obese type 2 diabetic leptin-deficient (ob/ob) mouse lacks macrovascular complications, i.e. occlusive atherosclerotic disease, and may therefore be a potential model for microvascular dysfunction. The present study aimed to test the hypothesis that these mice with an insulin resistant phenotype might display microvascular dysfunction in both coronary and renal vascular beds.

Impaired Coronary and Renal Vascular Function in Spontaneously Type 2 Diabetic Leptin-Deficient Mice.

Nephropathy is among the most frequent complications of diabetes and the leading cause of end-stage renal disease. Despite the success of novel drugs in animal models, the majority of the subsequent clinical trials employing those drugs targeting diabetic nephropathy failed. This lack of translational value may in part be due to an inadequate comparability of human disease and animal models that often capture only a few aspects of disease. Here we overcome this limitation by developing a multimolecular noninvasive humanized readout of diabetic nephropathy based on urinary peptidomics. The disease-modified urinary peptides of 2 type 2 diabetic nephropathy mouse models were identified and compared with previously validated urinary peptide markers of diabetic nephropathy in humans to generate a classifier composed of 21 ortholog peptides. This classifier predicted the response to disease and treatment with inhibitors of the renin-angiotensin system in mice. The humanized classifier was significantly correlated with glomerular lesions. Using a human type 2 diabetic validation cohort of 207 patients, the classifier also distinguished between patients with and without diabetic nephropathy, and their response to renin-angiotensin system inhibition. Thus, a combination of multiple molecular features common to both human and murine disease could provide a significant change in translational drug discovery research in type 2 diabetic nephropathy.

Urinary peptidomics provides a noninvasive humanized readout of diabetic nephropathy in mice.

The leptin-deficient BTBRob/ob mouse develops progressive albuminuria and morphological lesions similar to human diabetic nephropathy (DN), although whether glomerular hyperfiltration, a recognized feature of early DN that may contribute to renal injury, also occurs in this model is not known. Leptin replacement has been shown to reverse the signs of renal injury in this model, but in contrast, the expected renoprotection by angiotensin-converting enzyme (ACE) inhibition in BTBRob/ob mice seems to be limited. Therefore, to investigate the potential renal benefits of improved metabolic control in this model, we studied the effect of treatment with the dual peroxisome proliferator-activated receptor (PPAR) / agonist AZD6610 and compared it with the ACE inhibitor enalapril. AZD6610 lowered plasma glucose and triglyceride concentrations and increased liver size, but had no significant effect in reducing albuminuria, whereas enalapril did have an effect. Nephrin and WT1 mRNA expression decreased in the kidneys of BTBRob/ob mice, consistent with podocyte injury and loss, but was unaffected by either drug treatment: at the protein level, both nephrin and WT1-positive cells per glomerulus were decreased. Mesangial matrix expansion was reduced in AZD6610-treated mice. GFR, measured by creatinine clearance, was increased in BTBRob/ob mice, but unaffected by either treatment. Unexpectedly, enalapril-treated mice showed intrarenal arteriolar vascular remodeling with concentric thickening of vessel walls. In summary, we found that the BTBRob/ob mouse model shows some similarities to the early changes seen in human DN, but that ACE inhibition or PPAR/ agonism afforded limited or no kidney protection.

The effects of dual PPAR/ agonism compared with ACE inhibition in the BTBRob/ob mouse model of diabetes and diabetic nephropathy.

African Americans develop end-stage renal disease at a higher rate compared with European Americans due to 2 polymorphisms (G1 and G2 risk variants) in the apolipoprotein L1 (APOL1) gene common in people of African ancestry. Although this compelling genetic evidence provides an exciting opportunity for personalized medicine in chronic kidney disease, drug discovery efforts have been greatly hindered by the fact that APOL1 expression is lacking in rodents. Here, we describe a potentially novel physiologically relevant genomic mouse model of APOL1-associated renal disease that expresses human APOL1 from the endogenous human promoter, resulting in expression in similar tissues and at similar relative levels as humans. While naive APOL1-transgenic mice did not exhibit a renal disease phenotype, administration of IFN-γ was sufficient to robustly induce proteinuria only in APOL1 G1 mice, despite inducing kidney APOL1 expression in both G0 and G1 mice, serving as a clinically relevant "second hit." Treatment of APOL1 G1 mice with IONIS-APOL1Rx, an antisense oligonucleotide (ASO) targeting APOL1 mRNA, prior to IFN-γ challenge robustly and dose-dependently inhibited kidney and liver APOL1 expression and protected against IFN-γ-induced proteinuria, indicating that the disease-relevant cell types are sensitive to ASO treatment. Therefore, IONIS-APOL1Rx may be an effective therapeutic for APOL1 nephropathies and warrants further development.

Antisense oligonucleotide treatment ameliorates IFN-γ-induced proteinuria in APOL1-transgenic mice.

There is a need for improved animal models that better translate to human kidney disease to predict outcome of pharmacological effects in the patient. The diabetic BTBR mouse model mimics key features of early diabetic nephropathy in humans, but with chronic injury limited to glomeruli. To explore if we could induce an accelerated and more advanced disease phenotype that closer translates to human disease, we challenged BTBR mice with a high-protein diet (HPD; 30%) and followed the progression of metabolic and renal changes up to 20 wk of age. Animals on the HPD showed enhanced metabolic derangements, evidenced by further increased levels of glucose, HbA, cholesterol, and alanine aminotransferase. The urinary albumin-to-creatinine ratio was markedly increased with a 53-fold change compared with lean controls, whereas BTBR mice on the standard diet only presented an 8-fold change. HPD resulted in more advanced mesangial expansion already at 14 wk of age compared with BTBR mice on the standard diet and also aggravated glomerular pathology as well as interstitial fibrosis. Gene expression analysis revealed that HPD triggered expression of markers of fibrosis and inflammation in the kidney and increased oxidative stress markers in urine. This study showed that HPD significantly aggravated renal injury in BTBR mice by further advancing albuminuria, glomerular, and tubulointerstitial pathology by 20 wk of age. This mouse model offers closer translation to humans and enables exploration of new end points for pharmacological efficacy studies that also holds promise to shorten study length.

High-protein diet accelerates diabetes and kidney disease in the BTBR mouse.

We aimed to determine whether the sodium/glucose cotransporter family member SGLT3, a proposed glucose sensor, is expressed in the intestine and/or kidney, and if its expression is altered in mouse models of obesity and in humans before and after weight-loss surgery.

Article	Year
Impaired Coronary and Renal Vascular Function in Spontaneously Type 2 Diabetic Leptin-Deficient Mice. PloS one\| PubMed ID: 26098416	2015
Urinary peptidomics provides a noninvasive humanized readout of diabetic nephropathy in mice. Kidney international\| PubMed ID: 27528550	2016
The effects of dual PPAR/ agonism compared with ACE inhibition in the BTBRob/ob mouse model of diabetes and diabetic nephropathy. Physiological reports\| PubMed ID: 28292877	2017
Antisense oligonucleotide treatment ameliorates IFN-γ-induced proteinuria in APOL1-transgenic mice. JCI insight\| PubMed ID: 31217349	2019
High-protein diet accelerates diabetes and kidney disease in the BTBR mouse. American journal of physiology. Renal physiology\| PubMed ID: 31961715	2020
Intestinal sodium/glucose cotransporter 3 expression is epithelial and downregulated in obesity. Life sciences\| PubMed ID: 33385407	2021

Anette Ericsson

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