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BackgroundWe investigated the association between ambulatory blood pressure (BP) and the risk of home hypertension in a normotensive population and whether considering ambulatory BP improves the 10-year prediction model for home hypertension risk, which was developed in the previous Ohasama Study.MethodsIn this prospective study, we followed up with 410 participants (83.2% women; age, 53.6 years) without a home and ambulatory hypertension in the general population of Ohasama, Japan. The Cox model was used to assess the hazard ratios (HRs) for home hypertension (home BP ≥ 135/≥85 mmHg or the initiation of antihypertensive treatment) and model improvement.ResultsDuring a mean 14.2-year follow-up, 225 home hypertension incidences occurred. The HR (95% confidence interval) for home hypertension incidence per 1-SD higher (=6.76 mmHg) 24-hour systolic BP (SBP) was 1.59 (1.33 to 1.90), after adjustments for possible confounding factors, including baseline home SBP. Harrell’s C-statistics increased from 0.72 to 0.73 (P = 0.11) when 24-hour SBP was added to the basic 10-year home hypertension prediction model, which includes sex, age, body mass index, smoking status, office SBP, and baseline home SBP. Continuous net reclassification improvement (0.53, P ConclusionsA total of 24-hour SBP could be an independent predictor of future home hypertension. Home BP and 24-hour BP can longitudinally influence each other in the long term.

(Pro)renin receptor [(P)RR] is related to both the renin-angiotensin system and V-ATPase with various functions including stimulation of cell proliferation. (P)RR is implicated in the pathophysiology of diabetes mellitus and cancer. Hyperinsulinemia is observed in obesity-related breast cancer. However, the relationship between (P)RR and insulin has not been clarified. We have therefore studied the effect of insulin on (P)RR expression, cell viability and AKT phosphorylation under the conditions with and without (P)RR knockdown. Effects of insulin were studied in a human breast cancer cell line, MCF-7. Cell proliferation assay was performed by WST-8 assay. (P)RR expression was suppressed by (P)RR-specific siRNAs. The treated cells were analysed by western blotting and reverse transcriptase-quantitative polymerase chain reaction analysis. Insulin stimulated proliferation of MCF-7 cells and increased (P)RR protein expression, but not (P)RR mRNA levels. Moreover, autophagy flux was suppressed by insulin. Suppression of (P)RR expression reduced cell number of MCF-7 cells and AKT phosphorylation significantly in both the presence and the absence of insulin, indicating that (P)RR is important for cell viability and AKT phosphorylation. In conclusion, insulin upregulates the level of (P)RR protein, which is important for cell viability, proliferation, AKT phosphorylation and autophagy in breast cancer cells.

Increased central venous pressure in congestive heart failure is responsible for renal dysfunction, which is mediated by renal venous congestion. Pericyte detachment from capillaries after renal congestion might trigger renal fibrogenesis via pericyte-myofibroblast transition (PMT). Platelet-derived growth factor receptors (PDGFRs), which are PMT indicators, were upregulated in our recently established renal congestion model. This study was designed to determine whether inhibition of the PDGFR pathway could suppress tubulointerstitial injury after renal congestion.The inferior vena cava between the renal veins was ligated in male Sprague-Dawley rats, inducing congestion only in the left kidney. Imatinib mesylate or vehicle were injected intraperitoneally daily from 1 day before the operation. Three days after the surgery, the effect of imatinib was assessed by physiological, morphological and molecular methods. The inhibition of PDGFRs against transforming growth factor-β1 (TGFB1)-induced fibrosis was also tested in human pericyte cell culture.Increased kidney weight and renal fibrosis were observed in the congested kidneys. Upstream inferior vena cava (IVC) pressure immediately increased to around 20 mmHg after IVC ligation in both the imatinib and saline groups. Although vasa recta dilatation and pericyte detachment under renal congestion were maintained, imatinib ameliorated the increased kidney weight and suppressed renal fibrosis around the vasa recta. TGFB1-induced elevation of fibrosis markers in human pericytes was suppressed by PDGFR inhibitors at the transcriptional level.The activation of the PDGFR pathway after renal congestion was responsible for renal congestion-induced fibrosis. This mechanism could be a candidate therapeutic target for renoprotection against renal congestion-induced tubulointerstitial injury.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a systemic autoimmune disease characterized by necrotizing inflammation of the small blood vessels. ANCA-associated vasculitis is subclassified into three variants: granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, and microscopic polyangiitis (MPA). Myeloperoxidase (MPO) ANCA is a marker antibody for MPA. Interstitial pneumonia (IP) is occasionally complicated with MPA. However, only a few cases of idiopathic IP develop MPO-ANCA-positive conversion and MPA. Therefore, we present a case of a 70-year-old Japanese man with idiopathic IP who developed MPO-ANCA-positive conversion and MPA. We performed renal biopsy, which revealed pauci-immune crescentic glomerulonephritis. The patient was treated with intravenous methylprednisolone pulse therapy and oral prednisone, and the patient's laboratory data gradually improved with steroid therapy. The association between the production of MPO-ANCA and IP remains unclear, and the present case suggests that IP plays a role in inducing MPO-ANCA production. Patients with idiopathic IP should be followed-up carefully for an examination of increased MPO-ANCA levels and MPA development. In addition, early gastric cancer was detected during upper gastrointestinal endoscopy in our case, and it could also be important not to miss malignancy in patients with ANCA-associated vasculitis.

Fabry disease (FD) is an X-linked disorder of the sphingolipid metabolism, caused by deficiency or decreased activity of α-galactosidase A. We report a rare case of Fabry nephropathy (FN) in a 21-year-old Japanese female patient presenting with only urinary mulberry bodies; she was treated with pharmacological chaperone therapy (PCT) after renal biopsy. The patient underwent a detailed examination because her mother was diagnosed with FD in the Division of Community Medicine of our hospital. She did not have renal dysfunction or proteinuria, and only mulberry bodies were detected in the urine. The activity of α-galactosidase A was low, and genetic analysis revealed the R301Q mutation. A percutaneous renal biopsy was performed, and the findings revealed enlargement and vacuolation of glomerular podocytes by light microscopy, and myelin and zebra bodies were detected in podocytes by electron microscopy. She was diagnosed with FN by renal biopsy and gene analysis. PCT was selected as the treatment to prevent cardiac events and renal dysfunction. The present case suggests that renal biopsy may be necessary even for young women with only mulberry bodies for the diagnosis of FN. It could be useful to evaluate the effect of treatment using the counts of mulberry bodies in the urine. In addition, due to its oral administration, PCT may be suitable for patients who are unable to visit the hospital frequently.

This observational retrospective cohort study investigates the effect of antihypertensive therapy with angiotensin II receptor blockers (ARBs) or dihydropyridine calcium channel blockers (dCCBs) monotherapy on renal function using longitudinal real-world health data of a drug-naive, hypertensive population without kidney disease.Using propensity score matching, we selected untreated hypertensive participants ( n = 10 151) and dCCB ( n = 5078) or ARB ( n = 5073) new-users based on annual health check-ups and claims between 2008 and 2020. Participants were divided by the first prescribed drug.The mean age was 51 years, 79% were men and the mean estimated glomerular filtration rate (eGFR) was 78 ml/min per 1.73 m 2 . Blood pressure rapidly decreased by approximately 10% in both treatment groups. At the 1-year visit, eGFR levels decreased in the ARB group by nearly 2% but increased in the dCCB group by less than 1%. However, no significant difference was apparent in the annual eGFR change after the 1-year visit. The risk for composite kidney outcome (new-onset proteinuria or eGFR decline ≥30%) was lowest in the ARB group owing to their robust effect on preventing proteinuria: hazard ratio (95% confidence interval) for proteinuria was 0.91 (0.78-1.05) for the dCCB group and 0.54 (0.44-0.65) for the ARB group, compared with that for the untreated group after ending follow-up at the last visit before changing antihypertensive treatment.From the present findings based on the real-world data, ARBs can be recommended for kidney protection even in a primary care setting. Meanwhile, dCCB treatment initially increases eGFR with no adverse effects on proteinuria.

Lifetime risk (LTR) evaluates the absolute risk of developing a disease during the remainder of one’s life. It can be a useful tool, enabling the general public to easily understand their risk of stroke. No study has been performed to determine the LTR of cardiovascular disease in patients with chronic kidney disease (CKD) with or without hypertension; therefore, we performed this study in an Asian population. We followed 1525 participants (66.0% women; age 63.1 years) in the general population of Ohasama, Japan. We defined CKD as an estimated glomerular filtration rate (eGFR)

A 65-year-old woman was hospitalized for heart failure and pneumonia in a nearby hospital. She had been previously diagnosed as light chain (AL) amyloidosis and treated with melphalan plus dexamethasone (Mel-Dex), and lenalidomide plus dexamethasone (Len-Dex). She started treatment including antimicrobials and diuretics, but her renal function worsened progressively, and she was transferred to our hospital for nephrological care. She was treated with antimicrobials, noradrenaline, dobutamine, and continuous hemodiafiltration. Her general condition gradually stabilized, and she was switched to intermittent hemodialysis (HD). However, HD was discontinued due to intradialytic hypotension and the development of heparin-induced thrombocytopenia. Her renal replacement therapy was switched to peritoneal dialysis (PD), which enabled good volume control and stable cardiac function. She was discharged and is still in good condition, without serious complications and achieving a considerably better prognosis than was predicted. Our case suggests that PD is an effective modality for patients with AL amyloidosis with heart failure and renal dysfunction.

A patient with polycystic kidney disease had flank and back pain lasting for a month. We considered that her cysts led to the pain, which is a common symptom of polycystic kidney disease. However, a cancer hidden in large and multiple cysts caused the pain.

(Pro)renin receptor [(P)RR] is a component of the renin-angiotensin system and plays an essential role in the activity of vacuolar H+-ATPase and autophagy. (P)RR is expressed in cancer cells. However, the relationship among (P)RR, apoptosis and autophagy in the treatment of anti-cancer drugs has not been clarified. The aim of this study was to clarify the effects of anti-cancer drugs with autophagy-promoting activity on (P)RR expression in cancer cells. MCF-7 breast cancer cells and A549 lung cancer cells were treated with carboplatin or paclitaxel, and the expression of (P)RR, apoptosis markers and autophagy markers were assessed by RT-qPCR, western blot analysis and immunocytochemistry. Expression levels of (P)RR mRNA and soluble (P)RR protein were increased by carboplatin or paclitaxel in a dose-dependent manner. Immunofluorescence staining of (P)RR was increased in both MCF-7 and A549 cells treated by carboplatin or paclitaxel. Apoptosis induction was shown by elevated BAX/BCL2 mRNA levels and increased active caspase3-positive cells. Moreover, autophagy induction was confirmed by increased levels of autophagy-associated mRNAs and LC3B-II proteins. (P)RR knockdown by (P)RR-specific siRNA suppressed the cell viability in MCF-7 cells and A549 cells under the treatment of carboplatin or paclitaxel, suggesting that (P)RR deficiency inhibits the proliferation of cancer cells in a pathway different from carboplatin or paclitaxel. The present study showed that the expression of (P)RR mRNA and soluble (P)RR was increased by anti-cancer drugs with autophagy-promoting activity. Upregulated (P)RR and autophagy may constitute a stress adaptation that protects cancer cells from apoptosis.

Nephrolithiasis is a common renal disease with no effective medication. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, an anti-diabetic agent, have diuretic and anti-inflammatory properties and could prevent nephrolithiasis. Here, we investigated the potential of SGLT2 inhibition against nephrolithiasis using large-scale epidemiological data, animal models, and cell culture experiments.This study included the data of diabetic patients (n = 1,538,198) available in the Japanese administrative database and divided them according to SGLT2 inhibitor prescription status. For animal experiments, renal calcium oxalate stones were induced by ethylene glycol in Sprague-Dawley rats, and phlorizin, an SGLT1/2 inhibitor, was used for the treatment. The effects of SGLT2-specific inhibition for renal stone formation were assessed in SGLT2-deficient mice and a human proximal tubular cell line, HK-2.Nephrolithiasis prevalence in diabetic men was significantly lower in the SGLT2 inhibitor prescription group than in the non-SGLT2 inhibitor prescription group. Phlorizin attenuated renal stone formation and downregulated the kidney injury molecule 1 (Kim1) and osteopontin (Opn) expression in rats, with unchanged water intake and urine volume. It suppressed inflammation and macrophage marker expression, suggesting the role of the SGLT2 inhibitor in reducing inflammation. SGLT2-deficient mice were resistant to glyoxylic acid-induced calcium oxalate stone formation with reduced Opn expression and renal damages. High glucose-induced upregulation of OPN and CD44 and cell surface adhesion of calcium oxalate reduced upon SGLT2-silencing in HK-2 cells.Overall, our findings identified that SGLT2 inhibition prevents renal stone formation and may be a promising therapeutic approach against nephrolithiasis.

The number of patients aged ≥ 75 years and who need renal replacement therapy is steadily increasing. The study aimed to determine the safety of open surgery for peritoneal dialysis (PD) catheter placement in such patients.This prospective cohort study included patients who underwent PD catheter placement by open surgery under dexmedetomidine (DEX) and local anesthesia at our institution from January 2015 to February 2021. Patients were divided into the following two groups according to age at the time of surgery: ≥ 75 years (group A) and 75 years (group B). We compared the perioperative and postoperative complications (i.e., time to the first PD-related peritonitis and catheter obstruction requiring surgical intervention within 1 year) between the groups.A total of 118 patients were categorized into groups A (n = 65) and B (n = 53). No significant intergroup differences were observed in the postoperative fever, total duration of surgery, perioperative hemoglobin decrease, changes in the white blood cell count and C-reactive protein, postoperative catheter leakage, postoperative hospital stay, time to the first PD-related peritonitis, and catheter obstruction requiring surgical intervention within 1 year.The surgery for PD catheter placement by open surgery under DEX and local anesthesia in elderly patients is safe and effective.

Peritoneal dialysis (PD) catheter malposition is one of the complications of renal replacement therapy. This study aimed to determine the preoperative factors that cause PD catheter malposition.The prospective cohort study included patients who underwent PD catheter insertion surgery and had preoperative and postoperative computed tomography scans. We compared preoperative and intraoperative factors between the lower depth catheter group (group L) and upper depth catheter group (group U), and preoperative and intraoperative factors between the posterior catheter group (group P) and anterior catheter group (group A). In addition, PD catheter obstruction requiring surgical intervention in each group was followed up for 1 year.A total of 150 patients were categorized into groups L (n = 77) and U (n = 73), or groups P (n = 107) and A (n = 43). Body mass index (BMI; P = 0.02), subcutaneous fat area (P = 0.02), and rate of previous abdominal surgery (P = 0.01) were significantly lower in group L than in group U. In terms of anterior catheter position, females had more-anterior catheter positions. The time to PD catheter obstruction requiring surgical intervention (P = 0.03) was significantly lower in group U than in group L.High BMI, high subcutaneous fat area, high subcutaneous fat thickness, and previous abdominal surgery were identified as preoperative factors that cause the PD catheter to have an upper depth. Female sex was a preoperative influencing factor for the anterior PD catheter position.

Background and Aims While previous studies have reported the association between serum uric acid (SUA) and chronic kidney disease (CKD) incidence, the sex differences in this association remain controversial. Therefore, we examined the association between SUA levels and CKD incidence in middle-aged adults stratified by sex using data from a large-scale health check-up. Method We analyzed information from the JMDC database, which included the annual health check-up data of Japanese employees and their dependents aged Results The mean participant age was 44.1 years, and 29.6% were women. The mean SUA levels were 5.9 mg/dL and 4.1 mg/dL in men and women, respectively. During the mean follow-up period of 4.68 years, 12,589 participants developed CKD. The age-standardized incidence rates for CKD were 17.88/17.80 per 1000 person-years in men/women with SUA concentrations of 4.0–4.9 mg/dL, 209.76 per 1000 person-years in men with SUA ≥11.0 mg/dL, and 73.38 per 1000 person-years in women with SUA ≥ 9.0 mg/dL. The fully adjusted HRs (95% confidence interval [CI], P value) for CKD incidence in the groups with SUA concentrations of Conclusion The results of the present study demonstrated an increased risk of CKD in men with SUA concentrations of

Tolvaptan is an effective treatment for polycystic kidney disease (PKD), but also causes unfortunate polyuria. Hydrochlorothiazide (HCTZ) has been shown to reduce urine volume in nephrogenic diabetes insipidus, raising the possibility that HCTZ could also be effective in reducing tolvaptan-induced polyuria. In this study, we examined the combined administration of HCTZ and tolvaptan. Male PCK rats were divided into four groups of normal chow (Cont), normal chow plus tolvaptan, gavage HCTZ treatment, and tolvaptan + HCTZ. Biochemical examinations of the plasma and urine were performed as well as histological and molecular (mRNA and protein expression) analyses. Groups treated with tolvaptan had significantly higher 24 h urine excretion, which was significantly reduced in the tolvaptan + HCTZ group after 2 weeks. Cyst size, pERK protein expression, and Cyclin D1 mRNA expression were all significantly reduced in both the tolvaptan and tolvaptan + HCTZ groups, indicating that HCTZ did not affect the beneficial functions of tolvaptan. Notably, aquaporin 2 redistribution from the apical to intracellular domains was observed in tolvaptan-treated rats and was partially reversed in the tolvaptan + HCTZ group. The renal glomerular filtration rate was reduced in the tolvaptan + HCTZ group. Significantly lowered mRNA expression of neuronal nitric oxide synthase, prostaglandin E synthase 2 and renin were also found in the medulla, but not in the cortex. HCTZ reduces tolvaptan-induced polyuria without altering its beneficial effects on PKD. This novel therapeutic combination could potentially lead to better PKD treatments and improved quality of life for the affected patients.

Chronic kidney disease (CKD) is a global health burden. Previous studies have shown a J- or U-shaped association between serum uric acid (SUA) and cardiovascular mortality. We assessed the risk of CKD incidence in a refined SUA category in middle-aged adults stratified by sex.We analyzed data from 138,511 participants65 years old (29.6% women; mean age 44.1 years) without CKD at baseline acquired from the JMDC database. The Cox model was used to assess the adjusted hazard ratio (HR).During the mean follow-up period of 4.68 years, 12,589 participants developed CKD. The fully adjusted HRs (95% confidence interval [CI], p-value) for CKD incidence in men with SUA4.0, 10.0-10.9 and ≥ 11.0 mg/dL compared to men with SUA 4.0-4.9 mg/dL were 1.13 (1.01-1.26, p = 0.030), 1.98 (1.32-2.97, p = 0.0010), and 3.74 (1.68-8.35, p = 0.0013), respectively. The fully adjusted HRs for CKD incidence in women with SUA4.0, 8.0-8.9, and ≥9.0 mg/dL compared to women with SUA 4.0-4.9 mg/dL were 1.08 (1.01-1.16, p = 0.032), 2.39 (1.07-5.35, p = 0.034), and 3.20 (0.80-12.8, p = 0.10), respectively.Both high and low SUA levels were identified as risk factors for CKD incidence in middle-aged men and women. The association of SUA levels with the increase in the risk of CKD incidence differed by sex, and the range of SUA levels associated with an increase in the risk of CKD incidence varied by sex.

Renal venous congestion by increased central venous pressure in congestive heart failure is responsible for renal dysfunction. We have created a novel rat renal congestion model presenting increased renal interstitial hydrostatic pressure and vasa recta expansion, which leads to renal congestion-mediated fibrosis. Current clinical trials suggest the renoprotective effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors in heart failure patients; however, the underlying mechanisms are still discussing. Thus, we investigated the effect of phlorizin, a commercially available SGLT1/2 inhibitor, in our renal congestion model. All animal procedures were performed in accordance with the policies and guidelines of the “Position of the American Heart Association on Research Animal Use” and were approved by the Tohoku Medical and Pharmaceutical University Animal Experiment Committee (registration number: A18019-a, A19039-cn and A20005-cn). The inferior vena cava between the renal veins was ligated, which induced congestion only in the left kidney. Phlorizin (400 mg/kg body weight) or saline were injected subcutaneously daily from 1 day before the operation. Both the right control kidney and left congested kidney were collected 3 days after the surgery. Increased kidney weight and renal fibrosis were observed in the congested kidneys. Phlorizin attenuated the increased kidney weight and suppressed renal fibrosis staining. Molecules related to kidney injury (Kim1) and fibrosis (Fn1 and αSma) were also suppressed by Phlorizin in the congested kidney. Low-vacuum electron microscopy revealed the vasa recta dilatation in the congested kidney. This morphological change was alleviated by Phlorizin. These results suggest that SGLT1/2 inhibitor could suppress renal congestion-mediated fibrosis. This mechanism could be a potential therapeutic target for renoprotection against heart failure.

Lifetime risk (LTR) evaluates the absolute risk of developing a disease during the remainder of one's life. It can be a useful tool, enabling the general public to easily understand their risk of stroke. No study has been performed to determine the LTR of cardiovascular disease in patients with chronic kidney disease (CKD) with or without hypertension; therefore, we performed this study in an Asian population. We followed 1525 participants (66.0% women; age 63.1 years) in the general population of Ohasama, Japan. We defined CKD as an estimated glomerular filtration rate (eGFR)60 mL/min/1.73 m

The (P)RR ([pro]renin receptor) was identified as a new component of the renin-angiotensin system. We previously reported that high salt (HS) intake increased the (P)RR expression in several nephron segments of Sprague-Dawley rats. Other studies reported HS intake increased the XO (xanthine oxidase) activity and an MR (mineralocorticoid receptor) antagonist inhibited HS intake–increased (P)RR expression in the kidneys of Dahl salt-sensitive (DS) rats. The present study examined the effects of HS intake on (P)RR expression in the kidney of DS rats. Male DS rats were fed a normal salt diet or an HS diet for 4 weeks. Some of the rats fed on the HS diet were treated with the XO inhibitor, febuxostat, and the MR antagonist, spironolactone. Immunoblot and immunohistochemical analyses showed that HS intake increased (P)RR expression in the renal cortex by 22.6-fold, the proximal tubules by 4.9-fold and the distal tubules, respectively. Both febuxostat and spironolactone inhibited HS intake–increased (P)RR expression in the renal cortex. Febuxostat inhibited HS intake–increased (P)RR expression in the proximal tubules, whereas spironolactone inhibited HS intake–increased (P)RR expression in the distal tubules. Additionally, deoxycorticosterone acetate increased (P)RR expression in the renal cortex and distal tubules but not in the proximal tubules of DS rats fed the normal salt diet. These results indicate that HS intake greatly increases (P)RR expression in the renal cortex of DS rats. The mechanisms of HS intake–increased (P)RR expression may work in an XO-dependent manner in the proximal tubules and an MR-dependent manner in the distal tubules.

Background Inflammation, intrarenal renin-angiotensin system (RAS) activation, oxidative stress, and carbonyl stress have been postulated to play a fundamental role in controlling blood pressure. However, little is known about the association among renal RAS activation, carbonyl stress, and blood pressure elevation. Methods We evaluated the relationship between blood pressure elevation and either renal RAS activity or carbonyl stress in the general population (N = 355) in Japan. To minimize the effect of antihypertensive drug therapy, we divided participants into 3 groups (normotensive, hypertensive-with-non-medication, and hypertensive-with-medication). Intrarenal RAS activity and carbonyl stress were indicated by the urinary angiotensinogen (AGT) and carbonyl compound excretion levels, respectively. Results The urinary AGT and carbonyl compound excretion levels were significantly associated with blood pressure. Using a stepwise multiple regression analysis, we found that the urinary AGT excretion levels were strongly associated with blood pressure elevation, compared with inflammation, oxidative stress, and carbonyl stress markers, in all groups. Urinary carbonyl compound excretion was significantly associated with blood pressure in only the hypertensive-without-medication group. Furthermore, blood pressure was significantly increased in these participants, and both the urinary AGT and carbonyl compound levels were high. The urinary AGT excretion levels were strongly associated with elevated blood pressure in normotensive people, and inappropriate renal RAS activity and carbonyl stress independently contributed to the development of hypertension. Conclusions These findings suggest that RAS activation, particularly renal RAS activation exert a fundamental role in the pathogenesis of hypertension in the general population.

TGF-β1, which can cause renal tubular injury through a vacuolar-type H+-ATPase (V-ATPase)-mediated pathway, is induced by the glucose degradation product methylglyoxal to yield peritoneal injury and fibrosis. The present study investigated the roles of V-ATPase and its accessory protein, the (pro)renin receptor, in peritoneal fibrosis during peritoneal dialysis. Rats daily administered 20 mM methylglyoxal intraperitoneally developed significant peritoneal fibrosis after 7 days with increased expression of TGF-β and V-ATPase, which was reduced by the inhibition of V-ATPase with co-administration of 100 mM bafilomycin A1. The (pro)renin receptor and V-ATPase were expressed in acidic organelles and cell membranes of human peritoneal mesothelial cells. TGF-β1 upregulated the expression of collagens, α-SMA, and EDA-fibronectin, together with ERK1/2 phosphorylation, which was reduced by inhibition of V-ATPase, (pro)renin receptor, or the MAPK pathway. Fibronectin and the soluble (pro)renin receptor were excreted from cells by acidic organelle trafficking in response to TGF-β1; this excretion was also suppressed by inhibition of V-ATPase. Soluble (pro)renin receptor concentrations in effluents of patients undergoing peritoneal dialysis were associated with the dialysate-to-plasma ratio of creatinine. Together, these results demonstrate a novel fibrosis mechanism through the (pro)renin receptor and V-ATPase in the acidic organelles of peritoneal mesothelial cells.