Model Of Chronic Kidney Disease Research Articles

Nonsteroidal Mineralocorticoid Receptor Antagonist Finerenone Improves Diastolic Dysfunction in Preclinical Nondiabetic Chronic Kidney Disease.

The mineralocorticoid receptor plays a significant role in the development of chronic kidney disease (CKD) and associated cardiovascular complications. Classic steroidal mineralocorticoid receptor antagonists are a therapeutic option, but their use in the clinic is limited due to the associated risk of hyperkalemia in patients with CKD. Finerenone is a nonsteroidal mineralocorticoid receptor antagonist that has been recently investigated in 2 large phase III clinical trials (FIDELIO-DKD [Finerenone in Reducing Kidney Failure and Disease Progression in Diabetic Kidney Disease] and FIGARO-DKD [Finerenone in Reducing Cardiovascular Mortality and Morbidity in Diabetic Kidney Disease]), showing reductions in kidney and cardiovascular outcomes. We tested whether finerenone improves renal and cardiac function in a preclinical nondiabetic CKD model. Twelve weeks after 5/6 nephrectomy, the rats showed classic signs of CKD characterized by a reduced glomerular filtration rate and increased kidney weight, associated with left ventricular (LV) diastolic dysfunction and decreased LV perfusion. These changes were associated with increased cardiac fibrosis and reduced endothelial nitric oxide synthase activating phosphorylation (ser 1177). Treatment with finerenone prevented LV diastolic dysfunction and increased LV tissue perfusion associated with a reduction in cardiac fibrosis and increased endothelial nitric oxide synthase phosphorylation. Curative treatment with finerenone improves nondiabetic CKD-related LV diastolic function associated with a reduction in cardiac fibrosis and increased cardiac phosphorylated endothelial nitric oxide synthase independently from changes in kidney function. Short-term finerenone treatment decreased LV end-diastolic pressure volume relationship and increased phosphorylated endothelial nitric oxide synthase and nitric oxide synthase activity. We showed that the nonsteroidal mineralocorticoid receptor antagonist finerenone reduces renal hypertrophy and albuminuria, attenuates cardiac diastolic dysfunction and cardiac fibrosis, and improves cardiac perfusion in a preclinical nondiabetic CKD model.

Chronic kidney disease: a contraindication for using biodegradable magnesium or its alloys as potential orthopedic implants?

Magnesium (Mg) has gained widespread recognition as a potential revolutionary orthopedic biomaterial. However, whether the biodegradation of the Mg-based orthopedic implants would pose a risk to patients with chronic kidney disease (CKD) remains undetermined as the kidney is a key organ regulating mineral homeostasis. A rat CKD model was established by a 5/6 subtotal nephrectomy approach, followed by intramedullary implantation of three types of pins: stainless steel, high pure Mg with high corrosion resistance, and the Mg–Sr–Zn alloy with a fast degradation rate. The long-term biosafety of the biodegradable Mg or its alloys as orthopedic implants were systematically evaluated. During an experimental period of 12 weeks, the implantation did not result in a substantial rise of Mg ion concentration in serum or major organs such as hearts, livers, spleens, lungs, or kidneys. No pathological changes were observed in organs using various histological techniques. No significantly increased iNOS-positive cells or apoptotic cells in these organs were identified. The biodegradable Mg or its alloys as orthopedic implants did not pose an extra health risk to CKD rats at long-term follow-up, suggesting that these biodegradable orthopedic devices might be suitable for most target populations, including patients with CKD.

#1086 Blood-brain barrier permeability in patients with end-stage kidney disease: results from the BREIN study

Abstract Background and Aims Chronic kidney disease (CKD) is associated with an increased risk of cognitive impairment. In several models of CKD in rodents, we highlighted that CKD was associated with cognitive impairment and increased blood-brain barrier (BBB) permeability, quantified using 99mTc-DTPA scintigraphy imaging (SPECT/CT). BBB permeability was both correlated with cognitive impairment and with indoxyl sulfate (IS) levels. Inactivation of Aryl Hydrocarbon Receptor (AhR), receptor of the IS, protected the CKD mouse from the IS-induced BBB permeability. The objective of the BREIN study is to confirm the existence of an increased BBB permeability in humans with CKD. Method The prospective cohort study BREIN (NCT04328415) prospectively included patients with end-stage kidney disease (ESKD), and healthy volunteers (Ctrl) matched in age (±5 years), gender, and educational level to a patient. In patients and volunteers, BBB permeability was quantified by brain 99mTc-DTPA SPECT/CT performed by a senior nuclear physician and as percentage of injected activity (%IA). A battery of neuro-cognitive tests was performed, serum uremic toxins accumulation and AhR activation were assessed in all participants. Results 15 ESKD patients and 14 healthy volunteers were included. In ESKD patients had higher BBB permeability compared to controls: 0.29 0.07 vs. 0.14 0.06%IA, p < 0.0001. ESKD patients displayed lower MoCA score: 22.0 ± 5.0 vs. 27.3 ± 2.8, p = 0.008, impaired short-term memory (doors test): 12.5 ± 3.4 vs. 16.5 ± 3.4, p = 0.009, higher Beck depression score 8.1 ± 9.1 vs. 2.7 ± 3.4, p = 0.046, and slightly more daily cognitive complaints: 42.5 ± 29.3 vs. 29.8 ± 14.0 p = 0.153. ESKD patients displayed higher IS levels (2.8 ± 2.3 mmol/L vs. 0.9 ± 0.7 mmol/L, p = 0.006) and AhR activation (37.5 ± 17.8% vs. 24.7 ± 10.4%, p = 0.027). In ESKD patients, no significant correlation was found between BBB permeability and scores in cognitive tests, or serum uremic toxins levels. Conclusion This study confirms that ESKD patients display an increased BBB permeability compared to matched healthy volunteers, as well as cognitive and impairment. Association with uremic toxins and cognitive impairment needs to be assessed in larger cohorts.

#1825 Treating hyperphosphatemia in CKD via targeting Npt2a in the kidney

Abstract Background and Aims Targeting the renal sodium phosphate cotransporter 2a (Npt2a) offers a novel strategy for treating hyperphosphatemia in chronic kidney disease (CKD). In patients with and without reduced kidney function, hyperphosphatemia is associated with cardiovascular complications and currently treatment options are limited. Method To study the role of a novel Npt2a inhibitor (PF-06869206) we used in vitro (Opossum kidney [OK] cells) and in vivo approaches (C57Bl/6 and Npt2a knockout [Npt2a−/−] mice). As models of CKD, 5/6 nephrectomy (5/6 Nx) as well as novel Alport/Npt2a knockout mice (Alport/Npt2a−/−) were studied. Results OK cell experiments showed that the Npt2a inhibitor caused dose-dependent reductions of Na+-dependent Pi uptake (IC50: ∼1.4 μmol/L) and Michaelis-Menten kinetics identified a ∼2.4-fold higher Km for Pi in response to Npt2a inhibition with no significant change in apparent Vmax, indicating a competitive mode of action. In vivo, Npt2a inhibition enhanced urinary excretions of Pi, Ca2+, and Na+ dose-dependently, which is recapitulated in animal models with reduced kidney function (5/6 Nx and Alport mice). Reductions in plasma Pi occur within 30 minutes and reach a maximum (40-50%) after 2 hours, this coincided with ∼50% reductions in PTH levels. No effects on FGF23 were observed in this time frame. In C57Bl/6 mice qualitative immunohistochemistry after 24 hours showed reductions in Npt2a labelling in apical microvilli compared to vehicle treatment. Providing proof of concept, Npt2a−/− and Alport/Npt2a−/− mice confirmed specificity of the drug, effects on urinary and plasma Pi were absent. Further electrophysiological studies in acutely isolated connecting tubule/cortical collecting duct showed that open probability of the epithelial Na+ channel (ENaC) was reduced in response to Npt2a inhibition, suggesting that the natriuretic effect is mediated, at least in part, by inhibition of ENaC. Conclusion Npt2a inhibition offers a promising therapeutic approach for treating hyperphosphatemia and possibly offers the opportunity of reducing cardiovascular complications in CKD.

#2385 Inhibition of histone lysine demethylases 5 attenuates acute kidney injury but not acute kidney disease or chronic kidney disease

Abstract Background and Aims The histone lysine demethylases 5 (KDM5) are members of the family of Jumonji C domain-containing histone demethylases and catalyze the removal of di- and tri-methyl moieties from the fourth lysine of histone 3 (H3K4me2/3). It has been reported that the KDM5 family mediates a range of physiological and pathological events including cell differentiation, motility, senescence and epithelial-mesenchymal transition (EMT) via activating or repressing transcription in demethylase-dependent or independent manners in both homeostasis and disease. This study investigated the potential role of KDM5 in the development and progression of renal fibrosis in acute kidney injury (AKI), chronic kidney disease (CKD) or AKI to CKD transition (acute kidney disease, AKD). Method We evaluated therapeutic effects of KDM5 inhibition in AKI model of unilateral nephrectomy plus contralateral ischemia-reperfusion (IR) injury, AKI to CKD transition model of unilateral IR injury plus removal of contralateral uninjured kidney after 8 days of IR injury, and CKD model of unilateral ureteral obstruction (UUO) in mice. Results KDM5 C70 inhibitor prevented the increase of blood urea nitrogen and positive areas of trichrome, Sirius red, F4/80 and α-smooth muscle actin in injured kidneys 7 days after IR injury. Significant reductions in renal mRNA levels of pro-inflammatory cytokine/chemokine, EMT and pro-fibrotic markers (IL-1β, IL-6, TNF-α, CCL2, CCL3, GM-CSF, MMP9, fibronectin, vimentin, TGF-β1, COL4A1) were also observed with attenuated mRNA levels of KDM5a-c. In addition, renal protein levels of antioxidants such as catalase, SOD1 and SOD2 were increased in injured kidneys of KDM5 inhibitor-treated mice. However, parameters of renal fibrosis and inflammation were similar between mice without and with KDM5 inhibitor in both AKD and CKD models. Conclusion These data demonstrate that inhibition of KDM5 could prevent renal inflammation and fibrosis after acute and severe IR injury. The activation of KDM5 might be an early step in the development of renal fibrosis after AKI insult.

#571 Vitamin D receptor from VSMCs regulates vascular calcification during CKD: a potential role for miR-145a

Abstract Background and Aims Vascular calcification (VC) is a highly prevalent complication of chronic kidney disease (CKD) and is associated with the higher morbidity-mortality of patients with CKD. Vitamin D receptor (VDR) has been proposed to play a role in the osteoblastic differentiation of vascular smooth muscle cells (VSMCs), but the involvement of vitamin D (1, 25D) in VC associated to CKD is controversial. Accumulating evidence points to microRNAs as important players in the process of VC and recent studies show that miR-145a expression decreases in VSMCs during VC. In addition, VDR has been considered as a potent regulator of these small molecules, while miR-145a was identified as a target for 1, 25D. Our aim was to determine the role of local vitamin D signalling in VSMCs during CKD-induced VC and the involvement of miR-145a in this process. Method We used epigastric arteries from CKD-affected patients and from individuals with normal renal function. In vivo, we employed an experimental model of CKD-induced VC in mice with conditional deletion of VDR in VSMC (Myh11-CreERT2+ VDRlox/lox), while in vitro, we used mouse VSMC with (VDRwt) or without VDR (VDRko) incubated in calcification media. Transfection experiments with mmu-miR-145a-5p mimic or mmu-miR-145a-5p inhibitor were carried out in mouse VDRwt VSMCs. Results CKD-affected patients showed an increase in VC, alongside an increased arterial expression of VDR compared with controls with normal renal function. Conditional gene silencing of VDR in arterial VSMCs led to a significant decrease of VC in the mouse model of CKD, despite similar levels of renal impairment and serum calcium and phosphate levels. This was accompanied by lower arterial expression of osteopontin (OPN) and lamin A, and a higher expression of sclerostin (SOST). Runx2 was increased in arteries of both CKD groups independently of the presence of VDR in VSMCs. Furthermore, CKD-affected mice showed a reduction of miR-145a expression in calcified arteries, which was significantly recovered in animals with deletion of VDR in VSMCs. In vitro, the absence of VDR prevented VC, inhibited the increase of OPN, and re-established the expression of miR-145a. Forced expression of miR-145a in vitro in VDRwt VSMCs blunted VC and decreased OPN levels. Mir-145a levels markedly decreased both in human and mouse VDRwt VSMCs incubated in calcification media and 1, 25D. Overexpression of miR-145a suppressed the levels of OPN induced by 1, 25D, while the inhibition of mir-145a led to a significant increase in OPN levels, even higher than in cells treated solely with 1, 25D. A predicted miR-145a-binding site was detected at the 3’UTR of OPN mRNA transcript, through the extended seed region of the miRNA, pointing to OPN as a possible target of mir-145a during VC in CKD. There were no significant differences in Runx2 levels in 1, 25D-treated cells after transfection with mir-145a mimic or inhibitor. Conclusion VDR is induced in calcified VSMCs during CKD where it can modulate the expression of promoters and inhibitors of VSMC transdifferentiation, as well as small noncoding RNA molecules such as mir-145a that modulate VC. The regulation of these pathways by VDR seems to be essential for the settings of CKD-induced VC, as deletion of VDR from VSMCs prevented it.

#1110 The AHR antagonist CH223191 alleviates kidney injury and renal fibrosis in adenine-induced chronic kidney disease

Abstract Background and Aims The aryl hydrocarbon receptor (AhR) is a transcription factor that can be activated by a variety of endogenous and exogenous ligands, and is involved in varieties of biological processes. It has been confirmed that the expression of AhR in kidney is elevated in chronic kidney disease (CKD). However, the specific role of AhR signaling pathway in CKD and its molecular mechanism remain unclear. This study aims to investigate the role and underlying mechanism of AhR in CKD, providing potential targets for the treatment of CKD. Method Male C57/B6L mice were randomly divided into control group, model group and treatment group. The model group was fed 0.2% adenine diet for 14 days to establish CKD model, while the treatment group was treated with AhR antagonist CH223191. AhR agonist kynurenine and antagonist CH223191 was applied in mouse tubular epithelial (TCMK-1) cells to investigate the underlying mechanisms of AhR in vitro. The renal function, histological changes and renal fibrosis in mice were evaluated to explore the role of AhR in adenine-induced CKD. Histological changes were evaluated by PAS and MASSON stainings, immunohistochemistry and immunofluorescence. Western blot and qPCR were used to measure protein/gene transcription levels. Results The levels of serum creatinine (p < 0.0001) and urea nitrogen (p < 0.0001) in the model group were significantly increased, with obvious renal tubule dilation and renal fibrosis by PAS and MASSON staining. CH223191 treatment significantly reduced serum creatinine (p=0.0012) and urea nitrogen ( < 0.0001) levels in mice, and alleviated renal fibrosis histologically. Q-PCR and Western-Blot results showed that the renal expression level of AhR in the treatment group was decreased, while the expression levels of fibronectin (Fn) (p < 0.0001), α-smooth muscle actin (α-SMA) (p < 0.0001), type I collagen (p=0.0007) and transforming growth factor-β (TGF-b) (p=0.0027) were significantly decreased. In addition, the expression levels of N-GAL (p < 0.0001) and KIM-1 ( < 0.0001) molecular markers associated with kidney injury were reduced, suggesting that inhibiting AhR expression in vivo can reduce adenine-mediated kidney injury and renal fibrosis in CKD. In vitro experiments indicated that kynurenic acid could induce the expression of AhR and AhR downstream regulatory gene CYP1b1 and upregulated fibrosis-related genes in tubular epithelial cells, while CH223191 treatment downregulated the fibrosis-related genes in tubular epithelial cells. Conclusion AhR mediates renal injury and renal fibrosis in adenine-induced CKD mice. AhR antagonist CH223191 exerts a renal protective effect by reducing the expression of AhR in renal tubular epithelial cells, thereby alleviating renal injury and renal fibrosis.

#2617 Impact of CKD screening in high‑risk populations and guideline-directed therapy on RRT, CV events, and mortality in Europe: an IMPACT CKD analysis

Abstract Background and Aims Despite the rising and substantial burden of chronic kidney disease (CKD), there is a lack of recognition of CKD as a health priority in Europe. This contributes to underdiagnosis of CKD despite the potential for early detection and effective intervention to delay progression to late-stages (associated with costly and resource-intensive renal replacement therapy [RRT; i.e., dialysis and transplantation]). Further, diagnosed patients are undertreated when compared to current and upcoming CKD guidelines, leading to increased risk for progression to RRT and cardiovascular (CV) or other events. Early detection and intervention in high-risk populations, such as those with diabetes mellitus (DM) and hypertension (HTN) have shown cost-effectiveness; however, the broader implications of these strategies on CKD progression and clinical outcomes in a European context remains underexplored. Our study aims to illustrate the clinical benefit of targeted screening followed by an optimal compliance to guideline-directed treatment use to provide insight into potential CKD policies across Europe. Method Four country populations (Germany, Netherlands, Spain, United Kingdom [UK]) were simulated for 10-years (baseline: 2022; simulated years: 2023-2032) using the validated IMPACT CKD model to compare two scenarios: targeted screening for people with DM and/or HTN followed by 90% compliance to guideline-directed therapy versus current practice (i.e., underdiagnosis without screening and low treatment rates). Annual targeted screening was modelled using estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (UACR) testing. Initiation of therapies for people with diagnosed CKD was based on Kidney Disease Improving Global Outcomes guidelines. A 90% compliance to guideline-directed therapies was assumed to approximate maximum clinical benefit. Current practice was modelled based on the observed diagnosed rate without screening and the observed treatment rate in each country. The incremental population initiated on recommended therapies were modelled to experience a multiplicative treatment effect on GFR decline, CV events, and acute kidney injury (AKI) events. The model projected CKD and RRT prevalence, incidence of CV and AKI events with results shown for year 10 (2032), as well as cumulative all-cause mortality over the simulated 10-years. Results Results compare the high-risk population screening followed by guideline-directed treatment scenario to continuation of current practices for the four countries (Fig. 1). The identification of undiagnosed CKD, as well as lower rates of progression due to guideline-directed treatment was associated with a small rise in the number of total CKD patients, with increases in stage 1-2 by 3.5% to 5.0%, and stage 3-5 by 0.2% to 1.2%. There was a reduction in the number of undiagnosed CKD stage 1-2 patients by 49.2% to 71.6%, and stage 3-5 by 60.2% to 69.8%. The largest reductions were predicted for CV events (44.6% to 49.1%) followed by dialysis (22.6% to 41.9%). The strategy resulted in a decrease in cumulative 10-year all-cause mortality between 4.5% to 9.1% in CKD patients. Conclusion The study predicted significant clinical benefits from targeted CKD screening followed by guideline-directed interventions across all four European countries. Notably, this approach was forecasted to reduce undiagnosed CKD cases, dialysis, CV events, and mortality. These findings underscore the potential of acting earlier on CKD to mitigate the future CKD burden.

#1211 IGFBP-5/TGF-β1-mediated cell crosstalk between endothelia and tubular epithelia promotes renal fibrosis

Abstract Background and Aims Renal fibrosis is a common pathophysiological characteristic of chronic kidney disease (CKD) for which there is no effective treatment. The mechanism of renal fibrosis is complicated and remains unclear. Our previous study revealed that Insulin-like growth factor binding protein 5 (IGFBP-5) induces glycolytic activation in ECs and ultimately aggravates renal inflammation in diabetic kidney disease (DKD). This study aims to discover the relationship between IGFBP-5 and renal fibrosis. Method HK-2 and HUVEC cells were included in this study. UUO and ANN model were obstructed by Wild-type, IGFBP-5−/− and IGFBP-5flox/flox, cre mice. IGFBP-5, TGF-β and fibrosis makers were detected to explore the mechanism of IGFBP-5 in fibrosis. Results We found that the serum IGFBP-5 levels were significantly increased in CKD, that IGFBP-5 was dominantly localized in vascular endothelial cells (ECs) of kidney tissue, and that IGFBP-5 deficiency relieved renal fibrosis in CKD model mice. In vitro experiments indicated that IGFBP-5 exacerbated the fibrosis phenotypic alteration of tubular epithelial cells (TECs) by the TGF-β1/p-Smad3 signaling pathway. In turn, TGF-β1 could facilitate the synthesis of IGFBP-5 in ECs. The crosstalk between TECs and ECs mediated by IGFBP-5 and TGF-β1 was confirmed in a coculture system and endothelial-specific IGFBP-5-deficient mice. Conclusion Renal fibrosis is exacerbated by TEC-EC cellular crosstalk through the feedback loop consisting of IGFBP-5 and TGF-β1. These findings suggest that IGFBP-5 may be a new pathogenic factor in renal fibrosis and a potential new therapeutic target in CKD.

#294 Pragmatic literature reviews to populate a patient-level model to project the future clinical burden of CKD in low-and middle-income countries

Abstract Background and Aims Chronic Kidney Disease (CKD) affects approximately one in ten people around the world and is associated with an increased risk of adverse cardiorenal outcomes and mortality. In low- and middle-income countries (LMICs), the situation is aggravated by the paucity of kidney replacement therapies (KRTs). The objective of this study was to review the literature around CKD prevalence to understand the future epidemiology and economic burden of CKD in four LMICs from different continents. Method Inside CKD is a project designed to perform a microsimulation on a representative patient cohort to simulate renal disease progression into the future, and to model the effects of interventions based on population and disease characteristics. A pragmatic literature review was performed to obtain the inputs required to adapt the Inside CKD model to project the epidemiological and economic burden of CKD in four World Bank (2022) classified LMICs (Bolivia, Kenya, Sri Lanka and Uzbekistan). Using a data quality scoring system designed for the Inside CKD programme, a model input template was created to guide the country-specific literature search, to identify country demographics, epidemiological data including CKD staging data, renal registries, comorbidities (type 2 diabetes and hypertension), complications data (stroke, myocardial infarction, heart failure) and economic data including health costs and quality-of-life measures. Additional needs, challenges or country specific risk factors have also been identified. Results Literature reviews identified the best sources of demographic, epidemiological data as well as the main drivers of CKD in the four countries (e.g. hypertension, type 2 diabetes, heart failure). In addition, the reviews identified the best proxy data to use when country-specific data was not available. The UN World Prospects database was selected to derive the current and future population dynamics in the four countries. For Kenya, data from local sources, sub-Saharan African and Uganda were utilised to estimate the primary drivers of CKD: a 2018 meta-analysis reported a CKD prevalence of 18% in sub-Saharan Africa and was used to derive the eGFR and UACR data required to project CKD prevalence. CKD prevalence by stage was also identified for Bolivia. A large-scale study across 12 countries with consistent methodology estimated a CKD prevalence of around 5.5% in Bolivia. CKD data from Kazakhstan was selected as a proxy for Uzbekistan, which had a low prevalence of 1.3%. Country-specific challenges were also identified: in Kenya, results showed the importance of malnutrition, infection and climate as key drivers of CKD. In Sri Lanka and Uzbekistan, environmental factors (air and water pollution) and agricultural activity may contribute to high CKD prevalence in rural areas alongside more common risk factors such as hypertension. In Sri Lanka, CKD has been estimated at around 8.2% in the general population versus 15.0% in areas where groundwater is consumed. For Bolivia, additional parameters including occupation, altitude, seasonal weather variation and extreme temperatures may exacerbate CKD risk. Conclusion CKD is a major public health problem in LMICs but with diverse drivers. Local capacities and healthcare financing priorities vary between regions and depend upon competing demands of acute conditions, infections and non-communicable diseases. Forecasting future CKD burden is helpful for policy and planning purposes. There is a clear need to tailor policies beyond early screening and proactive management to tackle country-specific challenges such as occupation, infection, seasonal weather variation and genetics.

Renoprotective effects of Schoenoplectus tabernaemontani rhizomes aqueous extracts against Adriamycin-induced nephropathy in rats

In recent years, chronic kidney disease (CKD) has emerged as an increasingly significant issue due to the growing prevalence and high treatment costs. While recorded the positive diuretic effect of Schoenoplectus tabernaemontani, there is a lack of reports on its efficacy in treating CKD. The pharmacological effects and mechanisms of Schoenoplectus tabernaemontani rhizomes aqueous extracts (STE) in CKD were investigated by inducing a rodent model of CKD via injection of Adriamycin (ADR; 7.5 mg/kg) into the tail vein of Wistar rats. In summary, our findings suggest that STE has a beneficial effect on anti-renal fibrosis and can reverse ADR-induced renal injury by suppressing oxidative stress and inflammation. Therefore, STE holds promising potential as a treatment option for CKD.

Transcriptome Analysis of BAFF/BAFF-R System in Murine Nephrotoxic Serum Nephritis.

Chronic kidney disease (CKD) is an emerging cause for morbidity and mortality worldwide. Acute kidney injury (AKI) can transition to CKD and finally to end-stage renal disease (ESRD). Targeted treatment is still unavailable. NF-κB signaling is associated with CKD and activated by B cell activating factor (BAFF) via BAFF-R binding. In turn, renal tubular epithelial cells (TECs) are critical for the progression of fibrosis and producing BAFF. Therefore, the direct involvement of the BAFF/BAFF-R system to the pathogenesis of CKD is conceivable. We performed non-accelerated nephrotoxic serum nephritis (NTN) as the CKD model in BAFF KO (B6.129S2-Tnfsf13btm1Msc/J), BAFF-R KO (B6(Cg)-Tnfrsf13ctm1Mass/J) and wildtype (C57BL/6J) mice to analyze the BAFF/BAFF-R system in anti-glomerular basement membrane (GBM) disease using high throughput RNA sequencing. We found that BAFF signaling is directly involved in the upregulation of collagen III as BAFF ko mice showed a reduced expression. However, these effects were not mediated via BAFF-R. We identified several upregulated genes that could explain the effects of BAFF in chronic kidney injury such as Txnip, Gpx3, Igfbp7, Ccn2, Kap, Umod and Ren1. Thus, we conclude that targeted treatment with anti-BAFF drugs such as belimumab may reduce chronic kidney damage. Furthermore, upregulated genes may be useful prognostic CKD biomarkers.

Romosozumab rescues impaired bone mass and strength in a murine model of diabetic kidney disease

As international incidence of diabetes and diabetes-driven comorbidities such as chronic kidney disease (CKD) continue to climb, interventions are needed that address the high-risk skeletal fragility of what is a complex disease state. Romosozumab (Romo) is an FDA-approved sclerostin inhibitor that has been shown to increase bone mineral density and decrease fracture rates in osteoporotic patients with mild to severe CKD, but its effect on diabetes-weakened bone is unknown. We aimed to test Romo's performance in a model of combined diabetes and CKD. 6-week old male C57BL/6 mice were randomly divided into control (CON) and disease model (STZ-Ad) groups, using a previously established streptozotocin- and adenine-diet-induced model. After 16 weeks of disease induction, both CON and STZ-Ad groups were subdivided into two treatment groups and given weekly subcutaneous injections of 100 μL vehicle (phosphorus buffered saline, PBS) or 10 mg/kg Romo. Mice were euthanized after 4 weeks of treatment via cardiac exsanguination and cervical dislocation. Hindlimb bones and L4 vertebrae were cleaned of soft tissue, wrapped in PBS-soaked gauze and stored at 20C. Right tibiae, femora, and L4s were scanned via microcomputed tomography; tibiae were then tested to failure in 4-pt bending while L4s were compression tested. Romo treatment significantly increased cortical and trabecular bone mass in both STZ-Ad and CON animals. These morphological improvements created corresponding increases in cortical bending strength and trabecular compression strength, with STZ-Ad treated mice surpassing vehicle CON mice in all trabecular mechanics measures. These results suggest that Romo retains its efficacy at increasing bone mass and strength in diabetic kidney disease.

Group2 innate lymphoid cells ameliorate renal fibrosis and dysfunction associated with adenine-induced CKD

Renal fibrosis is a common pathway of chronic kidney disease (CKD) progression involving primary kidney injury and kidney diseases. Group 2 innate lymphoid cells (ILC2s) mediate type 2 immune responses irrespective of antigen presentation and play a reno-protective role in kidney injury and disease. In the present study, we observed a decrease in kidney-resident ILC2s in CKD and found that enrichment of ILC2s in the kidney ameliorates renal fibrosis. In CKD kidney, ILC2s preferentially produced IL-13 over IL-5 in response to IL-33 stimulation, regardless of ST2L expression. Moreover, GATA3 expression was decreased in ILC2s, and T-bet+ ILC1s and RORγt+ ILC3s were increased in CKD kidney. Adoptive transfer of kidney ILC2s into adenine-induced CKD model mouse improved renal function and fibrosis. Renal fibroblasts cultured with IL33-activated kidney ILC2s suppressed myofibroblast trans-differentiation through Acta2 and Fn-1 regulation. These results suggest that kidney ILC2s prevent CKD progression via improvement of renal fibrosis. Our findings also suggest that ILC2s may contribute to the development of new therapeutic agents and strategies for tissue fibroses.

Skeletal Muscle Injury in Chronic Kidney Disease-From Histologic Changes to Molecular Mechanisms and to Novel Therapies.

Chronic kidney disease (CKD) is associated with significant reductions in lean body mass and in the mass of various tissues, including skeletal muscle, which causes fatigue and contributes to high mortality rates. In CKD, the cellular protein turnover is imbalanced, with protein degradation outweighing protein synthesis, leading to a loss of protein and cell mass, which impairs tissue function. As CKD itself, skeletal muscle wasting, or sarcopenia, can have various origins and causes, and both CKD and sarcopenia share common risk factors, such as diabetes, obesity, and age. While these pathologies together with reduced physical performance and malnutrition contribute to muscle loss, they cannot explain all features of CKD-associated sarcopenia. Metabolic acidosis, systemic inflammation, insulin resistance and the accumulation of uremic toxins have been identified as additional factors that occur in CKD and that can contribute to sarcopenia. Here, we discuss the elevation of systemic phosphate levels, also called hyperphosphatemia, and the imbalance in the endocrine regulators of phosphate metabolism as another CKD-associated pathology that can directly and indirectly harm skeletal muscle tissue. To identify causes, affected cell types, and the mechanisms of sarcopenia and thereby novel targets for therapeutic interventions, it is important to first characterize the precise pathologic changes on molecular, cellular, and histologic levels, and to do so in CKD patients as well as in animal models of CKD, which we describe here in detail. We also discuss the currently known pathomechanisms and therapeutic approaches of CKD-associated sarcopenia, as well as the effects of hyperphosphatemia and the novel drug targets it could provide to protect skeletal muscle in CKD.

Lactobacillus acidophilus KBL409 protects against kidney injury via improving mitochondrial function with chronic kidney disease.

Recent advances have led to greater recognition of the role of mitochondrial dysfunction in the pathogenesis of chronic kidney disease (CKD). There has been evidence that CKD is also associated with dysbiosis. Here, we aimed to evaluate whether probiotic supplements can have protective effects against kidney injury via improving mitochondrial function. An animal model of CKD was induced by feeding C57BL/6 mice a diet containing 0.2% adenine. KBL409, a strain of Lactobacillus acidophilus, was administered via oral gavage at a dose of 1 × 109CFU daily. To clarify the underlying mechanisms by which probiotics exert protective effects on mitochondria in CKD, primary mouse tubular epithelial cells stimulated with TGF-β and p-cresyl sulfate were administered with butyrate. In CKD mice, PGC-1α and AMPK, key mitochondrial energy metabolism regulators, were down-regulated. In addition, mitochondrial dynamics shifted toward fission, the number of fragmented cristae increased, and mitochondrial mass decreased. These alterations were restored by KBL409 administration. KBL409 supplementation also improved defects in fatty acid oxidation and glycolysis and restored the suppressed enzyme levels involved in TCA cycle. Accordingly, there was a concomitant improvement in mitochondrial respiration and ATP production assessed by mitochondrial function assay. These favorable effects of KBL409 on mitochondria ultimately decreased kidney fibrosis in CKD mice. In vitro analyses with butyrate recapitulated the findings of animal study. This study demonstrates that administration of the probiotic Lactobacillus acidophilus KBL409 protects against kidney injury via improving mitochondrial function.

A Systematic Review and Meta-Analysis of microRNA Profiling Studies in Chronic Kidney Diseases.

Chronic kidney disease (CKD) represents an increasing health burden. Evidence suggests the importance of miRNA in diagnosing CKD, yet the reports are inconsistent. This study aimed to determine novel miRNA biomarkers and potential therapeutic targets from hypothesis-free miRNA profiling studies in human and murine CKDs. Comprehensive literature searches were conducted on five databases. Subgroup analyses of kidney diseases, sample types, disease stages, and species were conducted. A total of 38 human and 12 murine eligible studies were analyzed using Robust Rank Aggregation (RRA) and vote-counting analyses. Gene set enrichment analyses of miRNA signatures in each kidney disease were conducted using DIANA-miRPath v4.0 and MIENTURNET. As a result, top target genes, Gene Ontology terms, the interaction network between miRNA and target genes, and molecular pathways in each kidney disease were identified. According to vote-counting analysis, 145 miRNAs were dysregulated in human kidney diseases, and 32 were dysregulated in murine CKD models. By RRA, miR-26a-5p was significantly reduced in the kidney tissue of Lupus nephritis (LN), while miR-107 was decreased in LN patients' blood samples. In both species, epithelial-mesenchymal transition, Notch, mTOR signaling, apoptosis, G2/M checkpoint, and hypoxia were the most enriched pathways. These miRNA signatures and their target genes must be validated in large patient cohort studies.

Chronic kidney disease is accompanied by behavioral deficits in rodents

Clinical reports indicate a bidirectional relationship between mental illness and chronic systemic disease. Kidney injury and inflammation have been linked to brain dysfunction and alterations in learning and memory, as well as development of anxiety and depression, however, the underlying neurophysiological mechanisms remain elusive. In the current study, we investigated whether a chronic kidney disease (CKD) state is suffcient to produce deficits in rodent stress behaviors using a mild or severe model of CKD. Male rats were exposed to either 21 days of 0.75% adenine diet (AD) (model of mild CKD), or a combination of AD with unilateral nephrectomy (AD/Unx), prior to the start of AD (model of severe CKD). Control rats received sham surgery and remained on normal diet/chow throughout the experimental paradigm. CKD development in the rat models was determined by a significant increase in serum creatinine used as index for kidney function. Behavioral testing results demonstrate that mild CKD model, especially in combination with unilateral nephrectomy (severe CKD model), is accompanied by anhedonia (i.e., decreased sucrose preference) and increased anxiety-like behaviors in the novelty-suppressed feeding, open field and elevated plus maze tests. These findings suggest that impairment of kidney functionality is suffcient to increase behavioral emotionality in rodents consistent with development of depressive-like and anxiogenic phenotype. Ongoing studies are focused on identifying neurophysiological mechanisms linking renal disease with neurological abnormalities. Furthering our understanding of these mechanisms may aid in the development of improved treatments and prevention strategies for management of mental health comorbidities associated with kidney disease. Des Moines University IOER Research & Grant Award. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Chronic kidney disease alters tryptophan metabolite concentrations in male and female Sprague Dawley rats

Kynurenine is the first stable metabolite of tryptophan degradation. An increased ratio of kynurenine (KYN) to tryptophan (TRP) has been implicated in many disease states including chronic kidney disease (CKD) in humans. We hypothesized that we would see a similar increase in KYN/TRP in a CKD model in male and female rats. We induced CKD with a 0.25% adenine diet for 15 weeks and then measured a variety of renal parameters. Serum and kidneys were collected at sacrifice. We found that GFR was better preserved in CKD female rats compared to males (0.232 ± 0.056 vs. 0.081 ± 0.019 ml/min/100g BW) but was decreased significantly compared to controls (0.739 ± 0.048 female, 0.635 ± 0.099 male). Urine volume was elevated significantly in CKD rats compared to controls (80.0 ± 6.9 ml/day male CKD, 72.5 ± 4.7 female CKD vs. 13.3 ± 1.1 male CTL and 22.0 ± 1.8 female CTL). However, male CKD rats consumed significantly more water than female CKD (104.1 ± 7.3 ml/day male vs. 81.0 ± 5.1 female), although water consumption was similar in controls in both sexes (30.9 ± 2.6 male and 30.1 ± 2.5 female). Weekly food consumption and body weight were similar between same sex groups. Both male and female rats showed increased KYN/TRP in CKD compared to controls (0.102 ± 0.010 in male and 0.105 ± 0.011 in female CKD vs. 0.049 ± 0.005 and 0.033 ± 0.002 CTL). Similarly, kynurenic acid was elevated significantly in both sexes in CKD (305.7 ± 76.7 nmol/L male and 669.2 ± 140.7 female) compared to controls (92.3 ± 17.7 and 118.1 ± 14.7) respectively. These data show that the adenine feeding model of CKD reproduces many of the characteristics of human disease including alterations in TRP metabolites. This model will allow study of TRP metabolites in CKD progression. This work was supported by Career Development Award IK2 BX004997 from the United States Department of Veteran Affairs, Biomedical Laboratory Research and Development Service. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cognate Antigen-Independent Differentiation and Activation of Resident Memory T cells in Chronic Kidney Disease

Resident memory T cells (TRMs) are a memory subset of T cells which are retained locally within barrier and epithelial tissues such as the kidney and have also been noted for their role in perpetuating chronic inflammation. While T cells have gained recognition for their ability to modulate kidney inflammation in various models of kidney injury TRMs are still poorly understood and their contributions to sterile models of chronic kidney disease (CKD) are unknown. We hypothesized that kidney TRMs are activated and modulate kidney inflammation in the setting of CKD. We utilized an aristolochic acid (AA) model of murine CKD to investigate the presence of kidney TRMs via flow cytometry and characterized their transcriptional profile via single cell RNA sequencing (scRNAseq). We also measured kidney cytokine levels with an MSD cytokine plate. Six weeks after AA-induced CKD, kidney CD8+ T cells were significantly increased compared to control mice (29.6 ± 1.6% vs. 4.7 ± 0.6% of CD45+, respectively; p<0.0001), as were CD4+ T cells (34.4 ± 1.4% vs. 8.2 ± 0.7% of CD45+, respectively; p<0.0001). 53.6 ± 2.5% of CD8+ T cells expressed CD103, a TRM marker, in AA mice compared to 4.8 ± 1.2% in control mice, and 36.0 ± 1.7% vs 1.6 ± 0.3% of CD4+ T cells. Kidney protein lysates of AA mice had significantly higher levels of IFNγ than control kidneys (18.9 ± 1.6 vs. 2.9 ± 0.7 pg/mg, respectively; p=0.0003) as well as TNF (98.6 ± 8.9 pg/mg vs. 6.9 ± 0.8 pg/mg, respectively; p=0.0002) and IL-6 (247.6 ± 39.1 pg/mg vs. 75.4 ± 22.5 pg/mg, respectively; p=0.0226). scRNAseq of immune cells revealed T cells bearing TRM markers CD103 and CD49a which lacked expression of tissue egress molecules S1pr1, Sell, Ccr7, and Klf2. scRNAseq analysis of this TRM population also revealed downregulation of Eomes and Tbx21 transcription factors and upregulation of Runx3 transcription factor, all of which correspond with previously described TRM transcriptional profiles. We next evaluated signaling pathways involved with the survival and transcriptional profile of TRMs, namely IL-15 and TGF-β. While Il2rb and Il2rg (encoding IL-15 receptor subunits) were upregulated in TRMs, IL-15 protein lysate levels were not elevated in AA kidneys compared to controls (2,600 ± 145 pg/mg protein vs. 2,281 ± 96 pg/mg protein, respectively; p=0.0831). Tgfbr1 and Tgfbr2 (encoding TGF-β receptor subunits) were also upregulated in TRMs, but TGF-β protein lysate levels were not significantly elevated in AA kidneys compared to controls (2,158 ± 159 pg/mg protein vs. 1,924 ± 202 pg/mg protein, respectively; p=0.3886). Gene ontology pathway analysis showed enrichment of pathways involved in T cell receptor signaling. Because of this we assessed the kidney immune profile of transgenic OT-1 mice, which can only recognize specific ovalbumin residues in the context of MHC class 1 H-2Kb. Six weeks after AA-induced CKD, injured OT-1 mice still had a significant increase in the proportion of CD8+ T cells that were CD103+ compared to vehicle control OT-1 mice (47.3 ± 2.9% vs. 9.6 ± 1.6% of CD45+, respectively; p<0.0001) and CD4+ T cells that were CD103+ (26.7 ± 3.1% vs. 6.4 ± 2.4% of CD45+, respectively; p=0.0040). Here we demonstrate the differentiation and activation of TRMs during AA-induced CKD independent of cognate antigen interaction and highlight their activated profile, as well as an increase in kidney IFNγ, TNF, and IL-6, all proinflammatory cytokines typical of TRMs. Future studies will aim to determine the contributions of TRMs to CKD progression. F32 DK136187, T32 DK007545, R01 DK 118932, U54 DK137301. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.