Eirin, Alfonso

Abstract Background and Aims Almost 36 million US adults (1 in 7, 14%) suffer from chronic kidney disease (CKD), and precision strategies to offset the progression to end-stage kidney disease are in dire need. We took advantage of a novel preclinical translational model of CKD in swine and single nucleus RNA sequencing (snRNA-seq) to identify potential therapeutic targets via characterization of the renal cell-specific transcriptomic landscape. Method Normal and CKD pigs were euthanized after 14 weeks (n = 3/group), kidneys were harvested, nuclei isolated, libraries prepared, and snRNA-seq performed. UMAP plots were generated with Seurat (v4.4.0) using default parameters. The expression profile of marker genes across single nuclei clusters was visualized to define renal cell types and ranked based on the number of differentially expressed genes (DEGs). The top cell type was subjected to subsequent analysis and DEG sorted based on their involvement in angiogenesis, inflammation, and fibrosis, which are prominent injury pathways in the pathophysiology of CKD. To mechanistically study the role of top overlapping candidate DEGs and support their potential as therapeutic targets, in vitro studies in primary renal vascular endothelial cells (RECs) were performed. Results A total of 39,935 nuclei were analyzed. Thirty clusters were identified and filtered by canonical gene markers, revealing 18 unique renal cell types (Fig. 1A). Endothelial cells exhibited the highest number of DEGs (Fig. 1B). Volcano plots (Fig. 1C) and Venn diagram (Fig. 1D) analysis of endothelial cells identified unique DEGs among three main renal injury pathways in CKD (angiogenesis, inflammation, fibrosis), with 2 overlapping DEGs (VWF, LAMA3) upregulated and participating in inflammation and fibrosis. Targeted silencing of VWF and LAMA3 (randomly selected) in RECs using siRNA ameliorated C5b9 and TGF-ẞ immunoreactivity, suggesting attenuated inflammatory and fibrogenic activity, respectively (Fig. 1E). Conclusion Our work characterized the single-nuclear renal cell transcriptomic landscape of a translational model of CKD and identified endothelial cells as the cluster with the largest number of DEGs. Our observations support the candidacy of VWF and LAMA3 as potential targets to decrease renal endothelial cell inflammation and fibrosis, which could pave the way for new therapeutic strategies in patients with CKD.

Abstract Background and Aims Almost 36 million US adults (1 in 7, 14%) suffer from chronic kidney disease (CKD), which is more prevalent in the elderly, affecting up to 34% of adults ≥ over 65. CKD has limited therapeutic options, partly due to the lack of large animal models that allow the translational study of the impact of age on CKD. This work reports the first preclinical model of CKD in naturally aged swine. Method CKD was induced in naturally aged (6-9 years old) and young (3 months old) domestic pigs (bilateral renal artery stenosis + high-cholesterol/high-carbohydrate diet), followed for 14 weeks, and compared to normal controls (n = 4–5/group). Renal hemodynamics were quantified in vivo by multidetector CT. Metabolic parameters, renal microvascular (MV) architecture (3D-micro-CT), and morphometric analysis (staining) were investigated ex vivo. Results Both young and old pigs developed CKD, but the renal and metabolic phenotype was accentuated in aging animals. We found that superimposition of aging on CKD resulted in higher triglycerides, glucose levels, insulin resistance, and adipose tissue accumulation (subcutaneous, visceral, perirenal) (Fig. 1A and B), accompanied by a more severe renal dysfunction (C), cortical MV rarefaction, and reduced peritubular capillary density (D and E), and more severe structural damage disclosed by increased glomerulosclerosis, tubule-interstitial fibrosis, and tubular injury (F). Notably, the severity of renal MV rarefaction in aging CKD correlated with functional and structural abnormalities (simple linear regression analysis, G). Conclusion Our study establishes the first large animal model of aging CKD, allowing the investigation of age as a biological variable in kidney-metabolic diseases. Age exacerbates metabolic and renal abnormalities, and our data support the critical role of renal MV disease in aging CKD and suggest that its exacerbation is a potential key player in its progression. This novel translational platform could foster new studies toward the elucidation of novel mechanisms of age-related deterioration of renal function in CKD and for developing therapeutic interventions.

Abstract Background and Aims Patients with chronic kidney disease (CKD) have a higher risk of developing heart failure with preserved ejection fraction (HFpEF). Growing evidence supports that changes in cardiac microcirculation are a major pathophysiological driver of HFpEF. We created a model of CKD stage 3 that subsequently developed a cardiac phenotype with numerous traits of HFpEF (CKD-HFpEF), including microvascular (MV) rarefaction and decreased availability of the pro-angiogenic growth factor vascular endothelial growth factor (VEGF) in the heart. We hypothesize that cardiac VEGF therapy will attenuate MV injury and improve cardiac function in CKD-HFpEF. Method CKD and normal pigs (n = 6 each, 3 males/3 females) were studied for 14 weeks. In addition, CKD-HFpEF pigs (n = 6, 3 males/3 females) were treated after 6 weeks of disease with a single intracoronary (IC) administration of VEGF attached to a drug-delivery vector (ELP-VEGF) that increases cardiac targeting, and effects quantified 8 weeks later. Renal (multi-detector CT) and cardiac (echocardiography, PV loops) morphology and function were quantified in vivo, microvascular (MV) density (3D micro-CT) ex vivo, and cardiac expression of VEGF was quantified by qPCR and western blot, as VEGF-related genes by bulk mRNA-sequencing (n = 3/group). Results A single IC administration of ELP-VEGF improved MV density and rescued cardiac function compared to placebo similarly in male and female pigs and independent of hypertension (Fig. 1A–C). These improvements were accompanied by improved mRNA and protein expression of VEGF and restored expression of VEGF-related pro- and anti-angiogenic genes (Fig. 1D and E). Conclusion Our study supports the prominent role of cardiac MV disease in the development of HFpEF in CKD, supports the critical need for healthy VEGF signaling to preserve the heart in CKD, and shows the feasibility of a potential new therapeutic strategy via a targeted mechanistic intervention.

Chronic kidney disease (CKD), heart failure with preserved ejection fraction (HFpEF), and the recently defined cardiovascular-kidney-metabolic (CKM) syndrome are important challenges for the health care system, associated with a staggering increase in morbidity and mortality rates. Unfortunately, the complex pathophysiology of these processes remains to be fully elucidated, imposing hurdles to prevent their development and decelerate their progression. Large animal models are critical for understanding cardio-renal pathophysiology and for the discovery of new therapies. Among them, pig models offer significant translational power to grasp cardio-renal pathophysiology and to test the feasibility and efficacy of new strategies. We recently developed and characterized swine models of CKD, HFpEF, and CKM syndrome that closely recapitulate human disease and allow for the study of the impact of biological variables, such as sex or age, on these conditions. Furthermore, data from these studies revealed key mechanisms implicated in the pathogenesis of CKD, HFpEF, and CKM syndrome and identified potential targets for intervention. This focused mini review highlights the main features of these novel swine models and discusses ongoing and future research aimed at developing novel therapies.

Abstract Importance Mesenchymal stromal cells (MSCs) possess therapeutic properties that mediate repair. Obesity impairs MSC functionality and therapeutic efficacy, possibly by eliciting dynamic modifications of epigenetic markers, like 5-hydroxymethylcytosine (5hmC). Objective We hypothesized that human obesity alters the 5hmC landscape and anti-inflammatory capacity of adipose tissue-derived MSCs to activate the prominent inflammatory signaling mediator Interleukin (IL)-1β. Design, Setting, Participants, Intervention Adipose tissue samples were collected from obese and lean individuals (body mass index ≥30 or <30 kg/m2, respectively, n = 11 each) during weight-loss or kidney donation surgery. Main Outcomes and Measures MSCs were harvested and analyzed for 5hmC profiles (MeDIP-seq) and mRNA expression (RNA-seq) (n = 5 each). Subsequently, MSCs or a vehicle were injected into mice, (n = 6 each) and two-weeks later, kidneys were evaluated using in-vivo magnetic resonance imaging and ex vivo studies. The role of IL-1β was then studied in-vitro in MSC-induced immunomodulation using siRNA in macrophages. Results Compared to MSC from lean patients, obese-MSC genes showed 2087 differential 5hmC modifications and 175 differential mRNA expression. Among them, 14 genes with overlapping alterations were involved in regulation of cytokine production, prominently IL-1β. Injecting obese MSCs elevated renal expression of IL-1β and M1 macrophage count but lowered kidney perfusion. Silencing IL-1β in obese-MSCs in vitro reduced M1 phenotype switching in co-incubated macrophages. Conclusions and Relevance Obesity induces epigenetic and gene expression changes in MSCs, particularly in IL-1β, associated with impaired anti-inflammatory functionality of MSCs. Targeting IL-1β could be a useful therapeutic approach to modulate the decline in MSC functionality resulting from obesity.

Key Points We characterized the renal transcriptional profile at the single-nuclear level in a preclinical swine model of CKD. Our study reveals that renal endothelial cells represent the cluster with the highest number of differentially expressed genes related to inflammatory and fibrotic activity. These results offer new insights into CKD-induced transcriptional changes in renal endothelial cells at the single-nuclear level. Background The prevalence of CKD is on the rise, and precision strategies to offset the progression to ESKD are needed. We used a well-established preclinical translational model of CKD in swine and single-nucleus RNA sequencing (snRNA-seq) to identify potential therapeutic targets through characterization of the renal cell-specific transcriptomic landscape. Methods Normal and CKD pigs were studied in vivo and ex vivo after 14 weeks ( n =6/group). In randomly selected pigs ( n =3/group), kidneys were harvested, nuclei isolated, libraries prepared, and snRNA-seq performed. Protein expression of candidate differentially expressed genes (DEGs, log2FC >0.25, adjusted P value < 0.05) was determined by immunohistochemistry, and their expression in primary normal and CKD renal vascular endothelial cells was modulated (small interfering RNA) in vitro . Results A total of 52,213 nuclei were analyzed. Thirty clusters were identified and filtered by canonical gene markers, revealing 16 unique renal cell types. Endothelial cells were the top cell type exhibiting the highest number of DEGs, which were subsequently filtered by angiogenesis, inflammation, and fibrosis (major injurious pathways altered in CKD kidneys). Venn diagram analysis identified five unique overlapping DEGs in endothelial cells: vWF , LAMA3 , and KDR upregulated and PTGIS and ICAM1 downregulated in CKD versus normal kidneys. Venn diagram analysis indicates that vWF , LAMA3 , and ICAM1 participate in inflammatory and fibrotic signaling. Renal protein expression of these DEGs matched snRNA-seq findings. Furthermore, in vitro silencing of vWF and LAMA3 ameliorated endothelial cell inflammatory and fibrotic signaling. Conclusions Our work characterized the single-nuclear renal cell transcriptomic landscape of a translational model of CKD and singled out genes implicated in major renal injury pathways. These genes could serve as potential targets to pave the way for new therapeutic strategies in patients with CKD.

Abstract Renal artery stenosis (RAS) is the leading cause of secondary hypertension worldwide. However, current medical and surgical treatment modalities provide minimal benefits for kidney injury. Recent preclinical RAS models have demonstrated promising potential of human mesenchymal stem cells (MSC) and their daughter extracellular vesicles (EV) in improving murine renal function and attenuating inflammation. However, the extent and mechanisms underlying immune rejection of xenogeneic MSCs or EVs are yet undetermined. Therefore, adipose tissue was harvested from adult healthy patients. Adipose-derived MSCs were extracted and cultured, and EVs were isolated from their supernatants via ultra-centrifugation. Then, mice randomly assigned to RAS or sham surgery were divided into 6 groups: sham surgery, RAS, sham + MSC, RAS + MSC, sham + EV, and RAS + EV. Two weeks after intra-aortic injection of MSCs (5 × 105) or EVs (20 µg protein), we compared the intrarenal T-cell and macrophage accumulation, splenic B-cell numbers, circulating cytokines and anti-human antibodies levels among the groups. MSCs and EVs did not influence intrarenal immune cell infiltrations. However, MSCs significantly increased circulating anti-human antibodies. In the spleen, RAS + EV mice showed higher memory IgM+ B-cells but reduced CD19+ B-cells compared to RAS + MSC. In vitro T-cell recall assay showed that both MSCs and EVs exhibited reduced IFN-γ release upon re-stimulation, indicating an immunosuppressive effect. Therefore, xenogeneic MSCs induced a greater humoral response in mice, while EVs triggered a splenic cellular response, but neither elicits discernible kidney rejection. Our results provide key insights into the immunomodulatory mechanisms of MSCs and EVs and immune mechanisms underlying xenograft rejection.

The intrinsic reparative capacity of the adult mammalian kidney is restricted to the ability of scattered tubular-like cells (STCs) to repair damaged kidney cells. Our study provides evidence that chronic renal ischemia alters the mRNA/miRNA profile of angiogenic/vascular development genes of swine STCs, limiting their potential to repair injured tubular cells. Our observations may assist in developing new therapies to improve renal repair in individuals with chronic renal ischemia.

Mesenchymal stromal cells (MSCs) possess therapeutic properties, which can be blunted by obesity. Autophagy, a cellular recycling process, is essential for MSC function. We investigated the mechanisms by which obesity affects the properties of MSCs, with a focus on autophagy. Adipose tissue was obtained from kidney donors [body mass index (BMI) <30 kg/m 2 , non-obese] or individuals undergoing weight loss surgery (BMI ≥30 kg/m 2 , obese) for MSC harvesting ( n = 11 each); samples were randomized to sequencing (seq; n = 5 each) or functional studies ( n = 6 each). MSCs were sequenced to determine their epigenetic (5-hydroxymethylcytosine) and transcriptomic profiles across autophagy-related genes using hydroxymethylated DNA immunoprecipitation sequencing and mRNA-seq, respectively. Genes with shared trends in both datasets underwent Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR) validation. During functional studies, 2-h starvation was used to induce autophagy in vitro , enabling detection of changes in the protein expression of microtubule-associated protein 1A/1B-light chain-3 and in autophagic flux. Obesity amplified a starvation-induced reduction in autophagic flux in MSCs while promoting earlier generation of new autophagosomes during autophagy initiation. Integrated analysis of the two sequencing datasets revealed 124 differentially hydroxymethylated genes and 30 differentially expressed mRNAs. Among six overlapping autophagy-related genes, three exhibited same-direction trends. Of these, STX12 and SLC25A4 may be implicated in the impact of obesity on autophagic changes in MSCs. Therefore, human obesity may alter autophagy in adipose tissue–derived MSC, and thereby their metabolism and function.