Shared and Distinct Renal Transcriptome Signatures in 3 Standard Mouse Models of Chronic Kidney Disease

INTRODUCTION

Several mouse models with diverse disease etiologies are used in preclinical research for chronic kidney disease (CKD). Here, we performed a head-to-head comparison of renal transcriptome signatures in standard mouse models of CKD to assess shared and distinct molecular changes in three mouse models commonly employed in preclinical CKD research and drug discovery.

METHODS

All experiments were conducted on male C57BL/6J mice. Mice underwent sham, unilateral ureter obstruction (UUO), or unilateral ischemic-reperfusion injury (uIRI) surgery and were terminated two- and 6-weeks post-surgery, respectively. The adenine-supplemented diet-induced (ADI) model of CKD was established by feeding with adenine diet for 6 weeks and compared to control diet feeding. For all models, endpoints included plasma biochemistry, kidney histology, and RNA sequencing.

RESULTS

All models displayed increased macrophage infiltration (F4/80 IHC) and fibrosis (collagen 1a1 IHC). Compared to corresponding controls, all models were characterized by an extensive number of renal differentially expressed genes (≥11,000), with a notable overlap in transcriptomic signatures across models. Gene expression markers of fibrosis, inflammation, and kidney injury supported histological findings. Interestingly, model-specific transcriptome signatures included several genes representing current drug targets for CKD, emphasizing advantages and limitations of the three CKD models in preclinical target and drug discovery.

CONCLUSION

The UUO, uIRI, and ADI mouse models of CKD have significant commonalities in their renal global transcriptome profile. Model-specific renal transcriptional signatures should be considered when selecting the specific model in preclinical target and drug discovery.

MO069: Therapeutic Effects of Semaglutide as Mono and Combination Treatment with Lisinopril in a Mouse Model of Hypertension-Accelerated Diabetic Kidney Disease

BACKGROUND AND AIMS

Obesity, hyperglycemia and hypertension are critical risk factors for the onset and progression of diabetic kidney disease (DKD). Emerging evidence suggests that sodium-glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 receptor (GLP-1R) agonists improve cardiovascular and renal outcomes in type 2 diabetes patients. We have recently profiled the effects of SGLT2 and angiotensin-converting enzyme (ACE) inhibition in a model of advanced DKD facilitated by adeno-associated virus (AAV)-mediated renin overexpression in uninephrectomized (UNx) diabetic db/db mice (Østergaard et al., AJP Renal Physiol 321: F149–F161, 2021). In the present study, we evaluated the nephroprotective effects of the long-acting GLP1R agonist semaglutide, a long-acting GLP1R agonist currently approved for diabetes and obesity treatment and in clinical development for DKD. Semaglutide was profiled with and without combination treatment with lisinopril, a standard ACE inhibitor, in the db/db UNx-ReninAAV mouse model of DKD.

METHOD

Female db/db mice received a single intravenous injection of reninAAV 1 week prior to UNx. Six weeks post-nephrectomy, mice were randomized into treatment groups based on body weight and blood glucose in the fed state, and received vehicle (SC, QD), semaglutide 30 nmol/kg or semaglutide 30 nmol/kg (SC, QD) in combination with lisinopril 30 mg/kg (PO, QD) for 11 weeks. Treatment endpoints included blood pressure, plasma/urine biochemistry and histomorphometric markers of kidney injury.

RESULTS

Vehicle-dosed db/db UNx-ReninAAV mice developed hallmarks of hypertensive DKD characterized by severe albuminuria and advanced glomerulosclerosis. Compared with vehicle, semaglutide significantly reduced fed blood glucose and hemoglobin A1C levels, whereas no significant effect on plasma insulin was observed. Semaglutide significantly reduced both diastolic and systolic blood pressure as well as albuminuria and urine kidney injury molecule-1 (KIM-1) levels. Semaglutide improved kidney histopathology with notable reductions in glomerulosclerosis severity and percent area of KIM-1 staining. Combined lisinopril treatment led to further improvements in blood pressure, albuminuria and glomerulosclerosis. Semaglutide with and without lisinopril coadministration did not influence plasma urea, cystatin C and kidney CD11 expression.

CONCLUSION

Semaglutide improved disease hallmarks in the db/db UNx-ReninAAV mouse model of advanced DKD. Further benefits on renal functional and histological markers were obtained by combination with antihypertensive standard-of-care treatment.

P0990RENINAAV DOSE-DEPENDENTLY EXACERBATE ALBUMINURIA AND GLOMERULOSCLEROSIS, AND REDUCE GFR IN FEMALE UNINEPHRECTOMIZED DB/DB MICE

Background and Aims

Diabetic nephropathy (DN) is a long-term complication that occurs in ∼40% of diabetes patients and is a leading cause of end-stage renal disease. Despite recent emergence of SGLT2 inhibitors and GLP-1 receptor agonists for nephroprotection in diabetes patients, drug discovery has been halted by the lack of reliable rodent models exhibiting features of human DN. In a newly established mouse model of progressive DN, we investigate the effects of hypertension on kidney injury.

Method

Female db/db mice were uninephrectomized (UNx) at 8 weeks of age and injected i.v. with a Renin adeno-associated virus (AAV) construct at different doses to induce hypertension, while a LacZAAV construct was used as negative control. db/+ mice served as healthy controls. Hypertension was measured by tail cuff and glomerular filtration rate (GFR) transcutaneous recoding of FITC-sinistrin after i.v. bolus injection at 22 weeks of age. Urine ACR measured in spot urine samples collected before termination 24 weeks of age. Terminal kidney samples were collected for 3D image analyses, histopathological evaluation, and next generation sequencing for gene expression analyses.

Results

GFR measurements indicated hyperfiltration in all AAV-injected UNx db/db mice compared to db/+ mice, while ReninAAV tended to dose-dependently decrease GFR compared to LacZAAV in UNx db/db mice. Urine ACR was worsened by ReninAAV-induced hypertension compared to LacZAAV controls. Automized AI-based glomerulosclerosis scoring showed ReninAAV dose-dependent increases in glomerulosclerosis compared to LacZAAV controls. 3D kidney imaging demonstrated increased glomerular volume in LacZAAV UNx db/db mice compared to db/+ mice with no further effect in ReninAAV groups. RNA sequencing revealed upregulated gene expression markers of fibrogenesis (incl. Col1a1, Col3, Col4, Fn1, Lamc2 and Vim) and tubular injury markers (Ngal and Kim-1), as well as downregulation of proximal tubular markers (Megalin and Aqp1) in ReninAAV UNx db/db mice compare to LacZAAV controls.

Conclusion

ReninAAV-induced hypertension in female UNx db/db mice accelerates kidney injury in uninephrectomized db/db mice and aggravates GFR, albuminuria and glomerulosclerosis in parallel with increased expression of genes associated with tubular injury renal fibrosis. Together, these data confirm that ReninAAV UNx db/db mice is a reliable model of DN with features of late stage human disease.

Mastiha (Pistacia lentiscus) Improves Gut Microbiota Diversity, Hepatic Steatosis, and Disease Activity in a Biopsy-Confirmed Mouse Model of Advanced Non-Alcoholic Steatohepatitis and Fibrosis

SCOPE

As a result of the obesity epidemic, the prevalence of non-alcoholic steatohepatitis (NASH) is increasing. No drug is approved for the treatment of NASH. In this study, the effect of a nutritional supplement, Mastiha or Chios mastic gum, on metabolic and histological parameters and on the gut microbiome in mice with NASH and fibrosis was investigated.

METHODS AND RESULTS

Advanced NASH was induced by feeding C57BL/6J mice a diet rich in fat, sucrose, and cholesterol for 41 weeks. After randomization, animals received the NASH-inducing diet with or without 0.2% (w/w) Mastiha for a further 8 weeks. Disease activity was assessed by liver histology and determination of plasma transaminase activities. Fecal microbiota DNA extraction and 16S rRNA amplicon sequencing were used to determine the composition of the gut microbiome. Mastiha supplementation led to a significant reduction in circulating alanine aminotransferase (ALT) activity, improvement in hepatic steatosis and collagen content, and a reduction in NAFLD activity score. Furthermore, it resulted in a partial but significant recovery of gut microbiota diversity and changes in identity and abundance of specific taxa.

CONCLUSION

This is the first study demonstrating an improvement in disease activity in mice with advanced NASH with fibrosis by a diet containing Mastiha.

Provision of Amniotic Fluid During Parenteral Nutrition Increases Weight Gain With Limited Effects on Gut Structure, Function, Immunity, and Microbiology in Newborn Preterm Pigs

BACKGROUND

Small enteral boluses with human milk may reduce the risk of subsequent feeding intolerance and necrotizing enterocolitis in preterm infants receiving parenteral nutrition (PN). We hypothesized that feeding amniotic fluid, the natural enteral diet of the mammalian fetus, will have similar effects and improve growth and gastrointestinal (GI) maturation in preterm neonates receiving PN, prior to the transition to milk feeding.

MATERIALS AND METHODS

Twenty-seven pigs, delivered by cesarean section at ~90% of gestation, were provided with PN and also fed boluses with amniotic fluid (AF; n = 13, 24-72 mL/kg/d) or no oral supplements (nil per os [NPO]; n = 14) until day 5 when blood, tissue, and fecal samples were collected for analyses.

RESULTS

Body weight gain was 2.7-fold higher in AF vs NPO pigs. AF pigs showed slower gastric emptying, reduced meal-induced release of gastric inhibitory peptide and glucagon-like peptide 2, changed gut microbiota, and reduced intestinal permeability. There were no effects on GI weight, percentage mucosa, villus height, plasma citrulline, hexose absorptive capacity, and digestive enzymes. Intestinal interleukin (IL)-1β levels and expression of IL1B and IL8 were increased in AF pigs, while blood biochemistry and amino acid levels were minimally affected.

CONCLUSION

Enteral boluses of AF were well tolerated in the first 5 days of life in preterm pigs receiving PN. Enteral provision of AF before the initiation of milk feeding may stimulate body growth and improve hydration in preterm infants receiving PN. Furthermore, it may improve GI motility and integrity, although most markers of GI maturation remain unchanged.

Marked methylation changes in intestinal genes during the perinatal period of preterm neonates

Background

The serious feeding- and microbiota-associated intestinal disease, necrotizing enterocolitis (NEC), occurs mainly in infants born prematurely (5-10% of all newborns) and most frequently after formula-feeding. We hypothesized that changes in gene methylation is involved in the prenatal maturation of the intestine and its response to the first days of formula feeding, potentially leading to NEC in preterm pigs used as models for preterm infants.

Results

Reduced Representation Bisulfite Sequencing (RRBS) was used to assess if changes in intestinal DNA methylation are associated with formula-induced NEC outbreak and advancing age from 10 days before birth to 4 days after birth. Selected key genes with differentially methylated gene regions (DMRs) between groups were further validated by HiSeq-based bisulfite sequencing PCR and RT-qPCR to assess methylation and expression levels. Consistent with the maturation of many intestinal functions in the perinatal period, methylation level of most genes decreased with advancing pre- and postnatal age. The highest number of DMRs was identified between the newborn and 4 d-old preterm pigs. There were few intestinal DMR differences between unaffected pigs and pigs with initial evidence of NEC. In the 4 d-old formula-fed preterm pigs, four genes associated with intestinal metabolism (CYP2W1, GPR146, TOP1MT, CEND1) showed significant hyper-methylation in their promoter CGIs, and thus, down-regulated transcription. Methylation-driven down-regulation of such genes may predispose the immature intestine to later metabolic dysfunctions and severe NEC lesions.

Conclusions

Pre- and postnatal changes in intestinal DNA methylation may contribute to high NEC sensitivity in preterm neonates. Optimizing gene methylation changes via environmental stimuli (e.g. diet, nutrition, gut microbiota), may help to make immature newborn infants more resistant to gut dysfunctions, both short and long term.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-716) contains supplementary material, which is available to authorized users.

G protein-coupled receptor 39 deficiency is associated with pancreatic islet dysfunction

G protein-coupled receptor (GPR)-39 is a seven-transmembrane receptor expressed mainly in endocrine and metabolic tissues that acts as a Zn(++) sensor signaling mainly through the G(q) and G(12/13) pathways. The expression of GPR39 is regulated by hepatocyte nuclear factor (HNF)-1alpha and HNF-4alpha, and in the present study, we addressed the importance of GPR39 for glucose homeostasis and pancreatic islets function. The expression and localization of GPR39 were characterized in the endocrine pancreas and pancreatic cell lines. Gpr39(-/-) mice were studied in vivo, especially in respect of glucose tolerance and insulin sensitivity, and in vitro in respect of islet architecture, gene expression, and insulin secretion. Gpr39 was down-regulated on differentiation of the pluripotent pancreatic cell line AR42J cells toward the exocrine phenotype but was along with Pdx-1 strongly up-regulated on differentiation toward the endocrine phenotype. Immunohistochemistry demonstrated that GRP39 is localized selectively in the insulin-storing cells of the pancreatic islets as well as in the duct cells of the exocrine pancreas. Gpr39(-/-) mice displayed normal insulin sensitivity but moderately impaired glucose tolerance both during oral and iv glucose tolerance tests, and Gpr39(-/-) mice had decreased plasma insulin response to oral glucose. Islet architecture was normal in the Gpr39 null mice, but expression of Pdx-1 and Hnf-1alpha was reduced. Isolated, perifused islets from Gpr39 null mice secreted less insulin in response to glucose stimulation than islets from wild-type littermates. It is concluded that GPR39 is involved in the control of endocrine pancreatic function, and it is suggested that this receptor could be a novel potential target for the treatment of diabetes.