Renal mRNA Levels Research Articles

Chondroitin Sulfate Ameliorates Hypertension in Male Offspring Rat Born to Mothers Fed an Adenine Diet.

Pregnant women with chronic kidney disease (CKD) face increased risks of adverse outcomes in their adult offspring. Offspring rats born to dams fed an adenine diet develop hypertension, coinciding with dysregulated hydrogen sulfide (H2S) and nitric oxide (NO) pathways, as well as alterations in gut microbiota. Chondroitin sulfate (CS) is a multifunctional food known for its diverse bioactivities. As a sulfate prebiotic, CS has shown therapeutic potential in various diseases. Here, we investigated the protective effects of maternal CS supplementation against hypertension in offspring induced by an adenine diet. Mother rats were administered regular chow, 0.5% adenine, 3% CS, or a combination throughout gestation and lactation. Maternal CS supplementation effectively protected offspring from hypertension induced by the adenine diet. These beneficial effects of CS were connected with increased renal mRNA and protein levels of 3-mercaptopyruvate sulfurtransferase, an enzyme involved in H2S production. Furthermore, maternal CS treatment significantly enhanced alpha diversity and altered beta diversity of gut microbiota in adult offspring. Specifically, perinatal CS treatment promoted the abundance of beneficial microbes such as Roseburia hominis and Ruminococcus gauvreauii. In conclusion, perinatal CS treatment mitigates offspring hypertension associated with maternal adenine diet, suggesting that early administration of sulfate prebiotics may hold preventive potential. These findings warrant further translational research to explore their clinical implications.

#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.

Serum Amyloid A3 Promoter-Luciferase Reporter Mice Are Useful for Early Drug-Induced Nephrotoxicity Detection.

Early detection of drug-induced kidney injury is essential for drug development. In this study, multiple low-dose aristolochic acid (AA) and cisplatin (Cis) injections increased renal mRNA levels of inflammation, fibrosis, and renal tubule injury markers. We applied a serum amyloid A3 (Saa3) promoter-driven luciferase reporter (Saa3 promoter-luc mice) to these two tubulointerstitial nephritis models and performed in vivo bioluminescence imaging to monitor early renal pathologies. The bioluminescent signals from renal tissues with AA or CIS injections were stronger than those from normal kidney tissues obtained from normal mice. To verify whether the visualized bioluminescence signal was specifically generated by the injured kidney, we performed in vivo bioluminescence analysis after opening the stomachs of Saa3 promoter-luc mice, and the Saa3-mediated bioluminescent signal was specifically detected in the injured kidney. This study showed that Saa3 promoter activity is a potent non-invasive indicator for the early detection of drug-induced nephrotoxicity.

Phloretamide Protects against Diabetic Kidney Damage and Dysfunction in Diabetic Rats by Attenuating Hyperglycemia and Hyperlipidemia, Suppressing NF-κβ, and Upregulating Nrf2.

Potent hypoglycemic and antioxidant effects were recently reported for the apple-derived phenolic compound phloretamide (PLTM). The renoprotective effects of this compound are yet to be shown. This study aimed to examine the potential of PLTM to prevent diabetic nephropathy in streptozotocin-induced diabetic rats and to examine the possible mechanisms of protection. Non-diabetic and STZ-diabetic male rats were treated orally by gavage with either the vehicle or with PTLM (200 mg/kg; twice/week) for 12 weeks. PTLM significantly increased urine volume and prevented glomerular and tubular damage and vacuolization in STZ-diabetic rats. It also increased creatinine excretion and reduced urinary albumin levels and the renal levels of kidney injury molecule-1 (KIM-1), 8-hydroxy-2'-deoxyguanosine (8-OHdG), neutrophil gelatinase-associated lipocalin (NGAL), and nephrin in the diabetic rats. PTLM also prevented an increase in the nuclear levels of NF-κβ, as well as the total levels of tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), caspase-3, and Bax in the kidneys of diabetic rats. These effects were associated with reduced serum levels of triglycerides, cholesterol, and low-density lipoprotein cholesterol. In both the control and diabetic rats, PTLM significantly reduced fasting plasma glucose and enhanced the renal mRNA and cytoplasmic levels of Nrf2, as well as the levels of Bcl2, superoxide dismutase (SOD), and glutathione (GSH). However, PTLM failed to alter the cytoplasmic levels of keap1 in diabetic rats. In conclusion, PTLM prevents renal damage and dysfunction in STZ-diabetic rats through its hypoglycemic and hypolipidemic activities, as well as through its antioxidant potential, which is mediated by activating the Nrf2/antioxidant axis.

Progranulin deficiency attenuates tubulointerstitial injury in a mouse unilateral ureteral obstruction model.

Progranulin (PGRN) may have two opposing effects-inflammation and anti-inflammation-in different diseases. Although previous studies have reported that PGRN is involved in liver fibrosis, its involvement in tubulointerstitial fibrosis remains to be fully elucidated. Herein, we investigated these issues using PGRN-knockout (KO) mice treated with unilateral ureteral obstruction (UUO). Eight-week-old male PGRN-KO and wild-type (WT) mice were euthanized 3 and 7 days following UUO, and their kidneys were harvested for histopathological analysis. The renal expression of PGRN was evaluated by immunohistochemical and/or western blot analyses. The renal mRNA levels of markers related to inflammation (Il1b, Tnf, Il6, Ccl2, and Adgre1) and fibrosis (Tgfb1, Acta2, Fn1, and Col1a2) were evaluated using quantitative PCR. Histological changes such as renal tubular atrophy, urinary casts, and tubulointerstitial fibrosis were significantly improved in UUO-KO mice compared with UUO-WT mice. Quantitative PCR revealed that the mRNA expression levels of all inflammation- and fibrosis-related markers were lower in UUO-KO mice than in UUO-WT mice at 3 and/or 7 days after UUO. Moreover, PGRN and GRN protein levels were higher in the kidneys of UUO-WT mice than in mice that did not undergo UUO. Elevated GRN levels associated with excess PGRN levels may be involved in the occurrence of renal inflammation and fibrosis in UUO mice.

Eriodictyol attenuates doxorubicin-induced nephropathy by activating the AMPK/Nrf2 signalling pathway

Doxorubicin (DOX), an anthracycline chemotherapy, plays a prominent role in the treatment of various cancers. Unfortunately, its nephrotoxic effects limit its dosing and expose cancer survivors to increased morbidity and mortality. This study examined the nephroprotective effects of eriodictyol, a natural polyphenolic flavanone, in DOX-treated rats and the molecular pathways involved. Forty adult rats were divided into five groups (8/group): Control; eriodictyol (20 mg/kg/day); DOX (2.5 mg/kg, twice/week); DOX + Eriodictyol; and DOX + Eriodictyol + Compound C (CC), an AMPK inhibitor (0.2 mg/kg/day). Experiments continued for 21 days. Eriodictyol administration in DOX-treated rats reduced their fasting glucose levels and increased food intake, final body weight, and kidney weight, improved kidney function, prevented glomerular and tubular damage, and reduced collagen deposition and renal TGF-β1 mRNA levels. Furthermore, eriodictyol reduced their renal levels of Bax, caspase-3, and cytochrome-c; and enhanced the levels of Bcl2. Noticeably, in the kidneys of both controls and DOX-treated rats, eriodictyol increased levels of phosphorylated-AMPK(Thr172) but not AMPK mRNA nor protein levels. Also, in the same two groups, eriodictyol increased mRNA and nuclear Nrf2 levels, and levels of glutathione, superoxide dismutase, catalase, and hemeoxygenase-1, but reduced the levels of malonaldehyde, TNF-α, and mRNA, total, and nuclear levels of NF-κB. All the detected nephroprotective effects and improvements in the levels of markers of oxidation and inflammation were prevented by coadministration of CC. In conclusion, the coadministration of eriodictyol and DOX alleviates DOX-induced renal damage. In renal tissues, eriodictyol is an AMPK activator and its nephroprotective antioxidant and anti-inflammatory effects are AMPK-dependent.

Korean fermented soybean paste (Doenjang) has anti-obesity and anti-hypertensive effects via the renin-angiotensin system (RAS) in high-fat diet-induced obese rats.

The health-beneficial outcomes of doenjang, a Korean fermented food have been questioned due to its high salt content; moreover, the detailed underlying mechanisms of its health beneficial effects are not fully investigated. Thus, this study aimed to investigate doenjang's anti-obesity effects, anti-hypertensive effects, and its underlying mechanisms in high-fat diet -induced obesity. Sprague-Dawley rats fed with normal diet (ND), high-fat diet (HD), HD with 8% additive salt (HDS), or HD with doenjang containing 8% salt (HDJ) for 13 weeks. Compared to HD and HDS groups, the HDJ group had lower body and epididymal fat tissue weight gain and showed hypotrophy and hypoplasia. The RAS-related mRNA levels in the adipose tissue, including Renin and Ace were downregulated in the HDJ group compared to HD and HDS groups. Additionally, HDJ groups had significant improvements in systolic blood pressure, serum RAS-associated parameters (e.g., angiotensin II and aldosterone), renal mRNA levels related to RAS (e.g., angiotensin II receptor type 1 and 2), and aldosterone-associated mRNA expressions (e.g., mineralocorticoid receptor) in the kidney of HD-induced obese rats. Most importantly, HDS and HDJ groups showed distinct outcomes regarding adipogenesis and electrolytes metabolism, even though both diets contain a high level of salt. HDS group showed a higher epididymal fat tissue weight, mass, and adipocyte size than HDJ group. In addition, compared with HDJ group, HDS group significantly decreased the release of Na+ and K+ throughout the urine and feces. The present study addresses that doenjang has anti-obesity effects and anti-hypertensive effects by activating RAS in the adipose tissue and kidney, respectively. Additionally, this study also demonstrates that salt in doenjang and the additive salt differently influences adipogenesis and electrolytes metabolism, supporting doenjang has health advantageous effects regardless of its high salt contents.

Role of the transcription factor Fli-1 on the CXCL10/CXCR3 Axis.

The transcription factor Fli-1, a member of the ETS family of transcription factors, is implicated in the pathogenesis of lupus disease. Reduced Fli-1 expression in lupus mice leads to decreased renal Cxcl10 mRNA levels and renal infiltrating CXCR3+ T cells that parallels reduced renal inflammatory cell infiltration and renal damage. Inflammatory chemokine CXCL10 is critical for attracting inflammatory cells expressing the chemokine receptor CXCR3. The CXCL10/CXCR3 axis plays a role in the pathogenesis of various inflammatory diseases including lupus. Our data here demonstrate that renal CXCL10 protein levels are significantly lower in Fli-1 heterozygous MRL/lpr mice compared to wild-type MRL/lpr mice. Knockdown of Fli-1 significantly reduced CXCL10 secretion in mouse and human endothelial cells, and human mesangial cells, upon LPS or TNFα stimulation. The Fli-1 inhibitor, Camptothecin, significantly reduced CXCL10 production in human monocyte cells upon interferon stimulation. Four putative Ets binding sites in the Cxcl10 promoter showed significant enrichment for FLI-1; however, FLI-1 did not directly drive transcription from the human or mouse promoters, suggesting FLI-1 may regulate CXCL10 expression indirectly. Our results also suggest that the DNA binding domain of FLI-1 is necessary for regulation of human hCXCR3 promotor activity in human T cells and interactions with co-activators. Together, these results support a role for FLI-1 in modulating the CXCL10-CXCR3 axis by directly or indirectly regulating the expression of both genes to impact lupus disease development. Signaling pathways or drugs that reduce FLI-1 expression may offer novel approaches to lupus treatment.

Abstract P432: CTRP1 Contributes To Angiotensin II-Induced Hypertension Via Activation Of Intrarenal Renin

C1q/TNF-related protein 1(CTRP1) is generally regarded as an adipokine and its circulating level is elevated in patients with hypertension. However, the functional role and mechanism of CTRP1 in blood pressure (BP) regulation largely remains elusive. In the present study, we investigated the BP phenotype of global CTRP1 knockout mice (termed CTRP1 KO) during angiotensin II (AngII) infusion and further explored the underlying mechanism involving the intrarenal renin. At baseline, 4-mo-old CTRP1 KO mice exhibited no developmental abnormalities or had normal BPs as compared with wild-type controls (WT). AngII infusion (300 ng/min/kg) induced a 3-fold increase in plasma and urinary CTRP1 levels as assessed by ELISA, but it was undetectable in CTRP1 KO mice. By radiotelemetry, AngII-infused CTRP1 KO mice exhibited reduced MAP as compared with AngII-infused WT mice (MAP [mmHg] in Day 7: 124.1 ± 2.4 in CTRP1 KO mice vs. 135 ± 3.1 in WT mice, n = 4 for each group, p < 0.05 by Student’s t test). This reduction was accompanied by a diminished response in intrarenal renin expression, as evidenced by urinary total prorenin/renin excretion ([ng/24h]: 0.51 ± 0.08 in WT/Vehicle vs. 1.22 ± 0.12 in WT/AngII; 0.32 ± 0.11 in CTRP1 KO/Vehicle vs. 0.54 ± 0.09 in CTRP1 KO/AngII; p < 0.05 by Two-way ANOVA analysis) and renal medullary mRNA levels (qRT-PCR: 1.00 ± 0.18 in WT/Vehicle vs. 3.73 ± 0.59 in WT/AngII; 0.52 ± 0.21 in CTRP1 KO/Vehicle vs. 1.31 ± 0.37 in CTRP1 KO/AngII, p < 0.05 by Two-way ANOVA analysis). In contrast, renal cortical renin mRNA was suppressed by AngII infusion more significantly in WT than in CTRP1 KO mice. In cultured mouse collecting duct-derived M-1 cells, treatment with recombinant human CTRP1-His protein (hCTRP1-His) at 20 nM for 24 hours consistently upregulated renin expression at both protein (Densitometry: 1.00 ± 0.23 in Vehicle group vs. 2.58 ± 0.42 in hCTRP1-His group, p < 0.05) and mRNA levels (qRT-PCR: 1.00 ± 0.12 in Vehicle group vs. 11.60 ± 1.21 in hCTRP1-His group, p < 0.05) levels. Collectively, these findings provide evidence favoring CTRP1 as a regulator of intrarenal renin mediating AngII-induced hypertension and further suggest CTRP1 as a potential mediator of adipose-renal crosstalk.

Abstract P183: Porcupine Protects The Kidney By Suppressing Tubular Inflammation And Preserving Mitochondrial Integrity

Chronic Kidney Disease (CKD) progression may be slowed or stopped with early diagnosis and intervention, so developing novel therapies is paramount. The Wnt acyl transferase porcupine (PORCN) regulates the secretion of all 19 Wnt ligand isoforms that propagate β-catenin signaling. We find that mice with deletion of PORCN from kidney epithelia (PORCN iKKO) had augmented kidney injury in the nephrotoxic serum nephritis (NTS) model of CKD, with higher BUNs (202 ± 12 vs. 101 ± 38, mg/dL; p<0.01), and renal mRNA levels for NGAL (6.1±1.14 vs. 1.0±0.35 au, p=0.0013), KIM-1(2.5±0.65 vs. 1.0±0.26 au, p=0.046), collagen I (2.4±0.31 vs. 1.0±0.38 au, p=0.025), and fibronectin (2.5±0.35 vs. 1.0±0.27 au, p=0.006) compared to wild-type (WT) controls. PORCN iKKOs also had upregulated renal protein levels for collagen I (1.5 ± 0.2 vs. 1.0 ± 0.1 au; p=0.01) and fibronectin (1.8 ± 0.3 vs. 1.0 ± 0.1 au; p<0.01), recapitulating the mRNA patterns. We also detected marked TNFα mRNA upregulation in the PORCN iKKO kidneys vs WTs during CKD (2.6±0.67 vs. 1.0±0.30 au, p=0.036). TNFα is a potent driver of renal injury and fibrosis, acting via TNFα receptor 1(TNFR1) to promote ROS generation. At day 14 of NTS, PORCN iKKO kidneys contained higher levels of the ROS metabolite, 8-isoprostane (2348 ± 718 vs. 486 ± 77, pg/mg kidney; p=0.02), and expressed higher levels of mitochondrial dysfunction markers, including Drp1 (1.26 ± 0.06 vs. 1.0 ± 0.04 au; p<0.01) and p62 (1.3 ± 0.09 vs. 1.0 ± 0.07 au; p=0.07). TNFR1 inhibition (R-7050, 12mg/kg, IP, every other day) reduced BUNs (94.13 ± 3 vs. 90.26 ± 4.1, mg/dL; p=0.46) and renal Drp1 protein levels (1.4 ± 0.17 vs. 1.0 ± 0.15 au; p=0.11) in the PORCN iKKO cohort to WT levels. In primary renal tubular cells (RTCs), TNFα treatment (50ng/ml, 12hrs) induced 8-isoprostane generation (387 ± 119 vs. 121 ± 39, pg/ml in medium; p=0.07), corroborating our in vivo studies. Moreover, treatment of the RTCs with the Drp1 inhibitor mdivi-1 (MD1, 10μm) for 12 hours attenuated TNFα-induced accumulation of fibronectin and collagen I. Our studies suggest that PORCN in renal epithelia protects against kidney damage by limiting TNFα induction, thereby diminishing Drp1-mediated mitochondrial dysfunction and ROS generation.

Hydrophobic constituents of Polygonum multiflorum roots promote renal erythropoietin expression in healthy mice.

The roots of Polygonum multiflorum Thunberg (Polygonaceae) are used as a crude drug Kashu that is considered to improve blood deficiency based on a Kampo concept. Kashu has been included in Kampo formulas, such as Tokiinshi, which is used to treat eczema and dermatitis with itchiness by inhibiting inflammation and facilitating blood circulation in the skin. However, the effects of P. multiflorum roots on erythropoiesis are unclear. Previously, we isolated six phenolic constituents from an ethyl acetate (EtOAc)-soluble fraction of P. multiflorum root extract and identified them as (E)-2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucopyranoside [(E)-THSG], emodin, emodin-8-O-β-D-glucopyranoside, physcion, physcion-8-O-β-D-glucopyranoside, and catechin. To examine whether P. multiflorum roots facilitate erythropoiesis, the EtOAc-soluble fraction was orally administered to healthy ICR mice. When compared with mice fed a standard diet alone (Controls), the mice fed a diet including the EtOAc-soluble fraction exhibited significantly higher serum erythropoietin (Epo) levels. The renal Epo mRNA levels in EtOAc-soluble fraction-administered mice were significantly higher than those in the control mice. Then, we administered roxadustat, which is a drug to treat the patient suffering with renal anemia by specifically inhibiting hypoxia-inducible factor prolyl hydroxylases. Roxadustat slightly increased renal Epo mRNA levels in healthy mice. Administration of (E)-THSG, a major constituent, significantly increased serum Epo levels. It is likely that (E)-THSG may facilitate the process to convert inactive renal Epo-producing cells to active Epo-producing cells. Collectively, it is implied that (E)-THSG in the EtOAc-soluble fraction of P. multiflorum roots may primarily improve blood deficiency of Kampo concept by promoting erythropoiesis.

Knockdown of USF2 inhibits pyroptosis of podocytes and attenuates kidney injury in lupus nephritis.

As an essential factor in the prognosis of Systemic lupus erythematosus (SLE), lupus nephritis (LN) can accelerate the rate at which patients with SLE can transition to chronic kidney disease or even end-stage renal disease (ESRD). Proteinuria due to decreased glomerular filtration rate following podocyte injury is LN's most common clinical manifestation. Podocyte pyroptosis and related inflammatory factors in its process can promote lupus to involve kidney cells and worsen the occurrence and progression of LN, but its regulatory mechanism remains unknown. Accumulating evidence has shown that upstream stimulatory factor 2 (USF2) plays a vital role in the pathophysiology of kidney diseases. In this research, multiple experiments were performed to investigate the role of USF2 in the process of LN. USF2 was abnormally highly expressed in MRL/lpr mice kidney tissues. Renal function impairment and USF2 mRNA levels were positively correlated. Silencing of USF2 in MRL/lpr serum-stimulated cells significantly reduced serum-induced podocyte pyroptosis. USF2 enhanced NLRP3 expression at the transcriptional level. Silencing of USF2 in vivo attenuated kidney injury in MRL/lpr mice, which suggests that USF2 is important for LN development and occurrence.

TNF inhibits AQP2 expression via a miR137-dependent pathway

We previously showed that production of tumor necrosis factor-alpha (TNF) by the kidney, under normotensive, non-inflammatory conditions, inhibits expression of angiotensinogen in the proximal tubule and NKCC2 isoform A in the thick ascending limb of Henle’s loop via micro-RNA (miRNA)-dependent mechanisms. As miR-137 is a regulator of aquaporin-2 (AQP2) expression and TNF inhibits the expression of several extrarenal aquaporins, we tested the hypothesis that TNF inhibits AQP2 in the kidney via a miR-137-dependent mechanism. Target seed regions of mmu-miR-137 are conserved in the 3'-untranslated region (3’-UTR) of mouse AQP2 mRNA and luciferase assays showed that mmu-miR-137 directly targeted the 3’-UTR of mouse AQP2. Moreover, AQP2 expression was decreased by approximately 70% (P<0.05) in primary renal inner medullary collecting duct (IMCD) cells transfected with a miRNA mimic of mmu-miR-137, indicating that miR-137 directly targets AQP2 mRNA in these cells. The decrease in AQP2 mRNA accumulation was accompanied by a 53% decrease (P<0.05) in AQP2 protein expression when mmu-miR-137 was overexpressed in IMCD cells. Exposure of IMCD cells for 2 hr to 400 mosmol/kg H2O medium, made by increasing the osmolality by adding NaCl, increased mmu-miR-137 mRNA expression about 2-fold (P<0.05) as determined by quantitative RT-PCR analysis. These conditions also increased TNF production approximately 2-fold (P<0.05). To determine if the increase in mmu-miR-137 mRNA expression was related to the concomitant increase in TNF, cells were transfected with either a lentivirus construct to silence TNF or a control construct. The silencing construct, EGFP-shTNF-ex4, but not U6 control, decreased mmu-miR-137 mRNA expression in the IMCD cells exposed to 400 mosmol/kg H2O medium by approximately 63% (P<0.05) indicating that TNF upregulates mmu-miR-137 mRNA expression in IMCD cells. The levels of miR-137 also increased approximately 2-fold (P<0.05) in inner medulla isolated from age- and sex-matched male or female mice given 1% NaCl in the drinking water (HS) for 3 days. Six days after intrarenal injection of lentivirus EGFP-shTNF-ex4 to silence TNF, renal AQP2 mRNA levels increased approximately 3-fold (P<0.05) in inner medullary tissue isolated from male or female mice given HS compared with their respective control groups. In addition, renal silencing of TNF in male or female mice given HS exhibited an increase in AQP2 protein expression the inner medulla compared with control group as determined by Western blot analysis. Similarly, EGFP-shTNF-ex4, but not U6, decreased miR-137 levels in the inner medulla in male or female mice given HS. Taken together, these data reveal a novel mechanism by which TNF mediates the inhibition of AQP2 via miR-137, indicating that miR-137 may be important for studying TNF-regulated effects involving the AQP2 pathway on renal water excretion and blood pressure regulation. NIH grants R01 HL133077 and HL153525 This is the full abstract presented at the American Physiology Summit 2023 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.

Continuous Monochromatic Blue Light Exacerbates High-Fat Diet-Induced Kidney Injury via Corticosterone-Mediated Oxidative Stress.

Excessive illumination is one of the most severe environmental factors that impacts the organism. There is growing evidence that obesity significantly contributes to the onset of chronic kidney disease. However, the effect of continuous light on the kidney and which color can produce an apparent phenomenon remains elusive. In this study, C57BL/6 mice given either a normal diet (LD-WN) or a high-fat diet (LD-WF) were subjected to a light cycle of 12 h of illumination followed by 12 h of darkness for 12 weeks. Meanwhile, 48 high-fat diet mice were given a 24 h monochromatic light exposure of varying colors (white, LL-WF; blue, LL-BF; green, LL-GF) for 12 weeks. As expected, the LD-WF mice showed significant obesity, kidney injury, and renal dysfunction compared with the LD-WN group. LL-BF mice had worse kidney injury than LD-WF mice, including higher Kim-1 and Lcn2. The kidney of the LL-BF group showed marked glomerular and tubular injury, with decreased levels of Nephrin, Podocin, Cd2ap, and α-Actinin-4 compared to LD-WF. LL-BF also reduced the antioxidant capacity, including GSH-Px, CAT, and T-AOC, increased the production of MDA, and inhibited the activation of the NRF2/HO-1 signaling pathway. Furthermore, LL-BF upregulated the mRNA levels of the pro-inflammatory factors Tnf-α, Il-6, and Mcp-1, decreasing the inhibitory inflammatory Il-4 expression. We observed increased plasma corticosterone (CORT), renal glucocorticoid receptors (GR) expression, Hsp90, Hsp70, and P23 mRNA levels. These findings suggested that LL-BF increased CORT secretion and affected glucocorticoid receptors (GR) in comparison to the LD-WF group. Moreover, in vitro research demonstrated that CORT treatment increased oxidative stress and inflammation, which was counteracted by adding a GR inhibitor. Thus, the sustained blue light worsened kidney damage, possibly by inducing elevated CORT and increasing oxidative stress and inflammation via GR.

PS-B06-4: ADENINE NEPHROPATHY IS ALLEVIATED BY ANTI-INFLAMMATORY PROPERTY OF SODIUM BENZOATE

Background: D-amino acid oxidase (DAO), a molecule distributed in brain, liver, and kidney in human, oxidases d-amino acids to alpha-keto acids to produce hydrogen peroxides. Sodium benzoate (SB), a known DAO enzyme inhibitor, has anti-inflammatory property, although its effect has not been investigated in chronic kidney disease (CKD). Methods: Adenine induced CKD (AdCKD) or 2,8-dihydroxyadenine (2,8-DHA) nephropathy is applied for rodent CKD studies. AdCKD was induced by oral administration of adenine in C57BL/6JJcl mice with or without SB oral administration. AdCKD was also induced in DAO enzyme deficient mice (DAO-/-) and treated with or without SB. Human THP-1 cells and macrophages induced from THP-1 cells by phorbol 12-myristate 13-acetate were stimulated by LPS or TNF-alpha with or without SB to confirm the anti-inflammatory effect of SB. Results: AdCKD showed increased serum creatinine and urea nitrogen levels as well as kidney interstitial fibrosis and tubular atrophy score, which were significantly attenuated by the treatment of SB. Survival of AdCKD mice were significantly prolonged by 2.6-fold by SB administration. SB significantly decreased elevated kidney positive F4/80 immunohistochemistry area and renal mRNA level of macrophage markers and inflammatory markers of AdCKD. Human THP-1 cells and macrophages stimulated either by LPS or human TNF-alpha showed increased inflammatory gene mRNA expressions, which were significantly reduced by SB treatment. Conclusions: SB significantly ameliorated renal damage in AdCKD by suppressing inflammatory gene expressions and macrophage infiltration.

Abstract P250: Targeting The Thrombospondin-CD47 Axis Attenuates Blood Pressure And Renal Injury In Female Hypertensive (mRen2)27 Rats

Alterations in the extracellular matrix (ECM) can influence vascular stiffness and compromise organ function contributing to hypertension. A key component of the ECM is the type I integral membrane receptor CD47 that regulates the ECM by binding to the matricellular protein thrombospondin-1(TSP1). Increased circulating levels of TSP1 and CD47 activation are associated with cardiac and renal pathologies. Thus, the objective of the current study determined the efficacy of targeting CD47 with an anti-sense morpholinos to reduce blood pressure and renal injury in 20-week old hypertensive (mRen2)27 female rats. The CD47 morpholino (Morph) or the missense probe (Control) were dissolved in sterile PBS and administered by tail vein injection twice weekly for 6 weeks. Systolic blood pressures (SBPs) were monitored in conscious rats by a tail cuff auscultation and expression of RAS components assessed by RT-qPCR; all data are means ± SEM with n=8-10 per group. Prior to treatment, the baseline SBPs did not differ between the Control and Morph groups [196 ± 5 vs.197 ± 4 mmHg; p=0.87]. However, as early as one week of treatment, the CD47 Morph group exhibited a significant reduction in SBPs compared to the Control transgenics [185 ± 5 vs. 204 ± 3 mmHg; p<0.01]. At the end of the 6 week treatment period, SBPs remained significantly lower in the CD47 Morph group compared to the Controls [185 ± 4 vs.199 ± 3 mmHg; p<0.02]. In addition, CD47 blockade was associated with reduced proteinuria in the CD47 Morph compared to Controls [7 ± 1 vs. 26 ± 7 mg protein/24 hr excretion; p<0.05]. Regarding the mechanism of CD47 blockade to reduce blood pressure and proteinuria, mRNA analysis revealed lower renal renin mRNA levels in the CD47 Morph versus the Control group [0.54 ± 0.11 vs.1.04 ± 0.11; p<0.01]. Moreover, CD47 Morph treatment significantly reduced the mRNA levels of renal ACE [0.78 ± 0.13 vs.1.05 ± 0.14; p<0.05] and the renal AT1A receptor [0.74 ± 0.07 vs.1.05 ± 0.12; p<0.05], however, renal angiotensinogen mRNA levels were not different among the CD47 Morph and Controls [1.04.± 0.10 vs. 1.16 ± 0.20, p=0.83]. We conclude that silencing CD47 attenuates hypertension and renal injury in the female (mRen2)27 potentially by reducing expression of the renin-ACE-AT1 receptor axis within the kidney.

Abstract 061: Renal A20 Protects Against The Cisplatin-induced Kidney Injury

We recently reported that the ubiquitin-editing protein A20 in myeloid cells can limit the severity of hypertension. However, whether A20 in the kidney regulates renal injury without impacting systemic immune responses remains unclear. To address this question, we bred A20 flox/flox mice with the Pax8-rtTA and Tet-On lines, generating inducible renal epithelial cell A20 knockout mice (A20 iKKO). Mice with all 3 transgenes were used as the A20 iKKO group, whereas mice lacking the Pax8-rtTA or Tet-On transgene were wild-type (WT) controls. Before the experiments, mice were given 2mg/ml of doxycycline in water containing 5% (5 of 100) sucrose for 2 weeks so that A20 in renal tubular cells was ablated. 3 days after a single dose of cisplatin (20mg/kg), A20 iKKO mice exhibited more severe kidney injury compared to WTs (blinded injury score, 3.2±0.41 vs. 2.1±0.35 au, p=0.039). A20 iKKOs also had upregulated renal mRNA levels for NGAL (6.0±1.91 vs. 1.0±0.18 au, p=0.018) and KIM-1(3.3±1.2 vs. 1.0±0.29 au, p=0.07). Injured kidneys from the A20 iKKOs contained greater absolute numbers of T cells (123.6±8.5 vs. 53.8±4.7, x10 4 cells per gram kidney, p<0.001), macrophages (159.7±22.5 vs. 52.7±9.9, x10 4 cells per gram kidney, p<0.001), and dendritic cells (66.7±10.6 vs. 32.6±6.1, x10 4 cells per gram kidney, p=0.015) than WTs by flow cytometric analysis. In turn, mRNA levels for TNF-α (9.1±2.62 vs. 1.0±0.18 au; p=0.006) and IL-1β (4.1±1.06 vs. 1.0±0.13 au; p=0.009) were increased in the injured A20 iKKO injured kidneys vs WTs. Thus, A20 in the kidney epithelium protects against cisplatin-induced kidney injury by constraining renal immune cell accumulation and inflammatory cytokine release.

Abstract 005: Loss Of Resident Renal Dendritic Cells Prevents Salt-sensitive Hypertension And Pro-inflammatory Cytokine Production

Hypertension (HTN) is associated with an increase in pro-inflammatory cytokines. Sentinel renal dendritic cells (rDCs) form an intricate network within the kidney cortex. DCs can activate immune cells and secrete pro-inflammatory cytokines. We hypothesize that loss of renal-specific DCs (rDCs) prevents salt-sensitive hypertension (SS HTN) and reduces intra-renal chemokine and cytokine production. To test this hypothesis, male mice lacking a functional CX 3 CR 1 chemokine receptor (CX 3 CR 1 - EGFP+/+ ) or wild-type (Wt) were used. CX 3 CR 1 is required for DC localization to the kidney; thus these mice have a renal-specific DC-depletion. Mice were subjected to L-NAME (0.5mg/mL, 2 wks) and then a wash-out (1-2wks), followed by HS (4%) or normal chow (NC) for the remainder of the study. Mice were implanted with telemetry devices and mean arterial pressure (MAP) assessed. Total kidney mRNA was isolated and pro-inflammatory chemokine/cytokine levels were determined using RT-PCR (n=4-6). Wt mice exhibited a progressive increase in MAP, with rDC-depleted mice having significantly lower MAP by week 3 (121±4 vs . 114±3mmHg, *p<0.05). We observed a significant increase in renal mRNA levels of IL-27 (3.24 fold change **p<0.01) and IL-5 (3.76 fold change ****p<0.001) in Wt mice during SS HTN. Renal levels of IL-5 (1.69 fold change *p<0.05), IL-33 (0.72 fold change *p<0.05) and CXCL10 (0.52 fold change *p<0.05) were significantly reduced in rDC-depleted mice during SS HTN, as compared to Wt. When compared to NC, IL-10 levels were unchanged following SS HTN and no differences observed in rDC-depleted mice. Here, we show that rDC-depletion reduces the SS HTN response and that rDCs are necessary for the intra-renal increase of some pro-inflammatory chemokines and cytokines. These data suggest that sentinel innate immune cells within the kidney are crucial in the pathogenesis of SS HTN.

Renal Megalin mRNA Downregulation Is Associated with CKD Progression in IgA Nephropathy

Introduction: Megalin plays an important role in proximal tubule uptake of filtered proteins. Downregulation and dysfunction of megalin were previously demonstrated in IgA nephropathy (IgAN); however, its relationship to IgAN progression remains unclear. Methods: We measured renal megalin mRNA and miR-148b, previously identified as a regulator of megalin, in a retrospective cohort of 417 IgAN patients at the time of biopsy, and evaluated their associations with chronic kidney disease (CKD) progression event, defined as end-stage renal disease or ≥40% decline in estimated glomerular filtration rate, using Cox proportional hazard models. Risk classification statistics were calculated for CKD progression. Results: During a median follow-up of 43 months, 121 (29.0%) patients reached the CKD progression event. Patients in the highest tertile of renal megalin mRNA had a lower risk for CKD progression than in the lowest tertile (hazard ratio (HR): 0.407, 95% confidence interval (CI) 0.231–0.719; p = 0.002). Log megalin mRNA was independent and negatively associated with CKD progression in IgAN (HR: 0.529, 95% CI 0.377–0.742; p < 0.001). The addition of renal megalin mRNA to a model with traditional risk factors improved risk prediction of disease progression (C statistic from 0.76 to 0.80; integrated discrimination index: 0.04 [95% CI: 0.02–0.07]). Moreover, patients in the highest tertile of renal miR-148b had a 2.3-fold higher risk for CKD progression compared with those in the lowest tertile. Conclusions: Lower renal megalin mRNA levels were associated with a greater risk of CKD progression in IgAN independent of clinical and pathological characteristics, suggesting that renal megalin could be an important prognostic factor for IgAN.

Interleukin-17A is closely correlated with the progression of renal epithelial-mesenchymal transition in spontaneously hypertensive rats

To explore the role of interleukin-17A (IL-17A) in renal epithelial- mesenchymal transition (EMT) in essential hypertensive nephropathy. Four-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats (control group) were both randomized into 4 groups (n=5) for observation at 4, 6, 10 and 30 weeks of age. Blood pressure of the rats was monitored using a noninvasive tail artery blood pressure measurement instrument. The percentage of Th17 cells in the splenocytes was analyzed using flow cytometry. The mRNA and protein expression levels of IL-17A, iNOS, Arg-1, E-cadherin, and α-SMA in the kidneys of the rats were detected using RT-PCR and immunohistochemical staining, respectively, and plasma levels of IL-17A were regularly detected using ELISA. At the age of 6 weeks, the SHRs began to show significantly higher blood pressure with greater Th17 cell percentage in the splenocytes and high renal expression and plasma level of IL-17A than WKY rats (P < 0.05 or P < 0.01). At 30 weeks, renal expression of E-cadherin mRNA and protein was significantly lower and the expression of Arg-1 mRNA and protein was significantly higher in SHR than in WKY rats (P < 0.01). Compared with the WKY rats, the SHRs showed significantly higher mRNA and protein expressions of iNOS at 6 and 10 weeks (P < 0.05 or 0.01) and higher α-SMA mRNA and protein expressions since 10 weeks of age (P < 0.05 or 0.01). In SHRs older than 10 weeks, renal IL-17A mRNA and protein expression levels were negatively correlated with those of E-cadherin (r=-0.731, P < 0.05; r=-0.827, P < 0.01) and positively correlated with those of α-SMA (r=0.658, P < 0.05; r=0.968, P < 0.01). IL-17A is closely correlated with the progression of renal EMT in SHR and plays its role possibly by mediating M1/M2 polarization of renal infiltrating macrophages.