Widening the Prostacyclin Paradigm: Tissue Fibroblasts Are a Critical Site of Production and Antithrombotic Protection.

BACKGROUND: Prostacyclin is a fundamental signaling pathway traditionally associated with the cardiovascular system and protection against thrombosis but which also has regulatory functions in fibrosis, proliferation, and immunity. Prevailing dogma states that prostacyclin is principally derived from vascular endothelium, although it is known that other cells can also synthesize it. However, the role of nonendothelial sources in prostacyclin production has not been systematically evaluated resulting in an underappreciation of their importance relative to better characterized endothelial sources. METHODS: To address this, we have used novel endothelial cell-specific and fibroblast-specific COX (cyclo-oxygenase) and prostacyclin synthase knockout mice and cells freshly isolated from mouse and human lung tissue. We have assessed prostacyclin release by immunoassay and thrombosis in vivo using an FeCl3-induced carotid artery injury model. RESULTS: We found that in arteries, endothelial cells are the main source of prostacyclin but that in the lung, and other tissues, prostacyclin production occurs largely independently of endothelial and vascular smooth muscle cells. Instead, in mouse and human lung, prostacyclin production was strongly associated with fibroblasts. By comparison, microvascular endothelial cells from the lung showed weak prostacyclin synthetic capacity compared with those isolated from large arteries. Prostacyclin derived from fibroblasts and other nonendothelial sources was seen to contribute to antithrombotic protection. CONCLUSIONS: These observations define a new paradigm in prostacyclin biology in which fibroblast/nonendothelial-derived prostacyclin works in parallel with endothelium-derived prostanoids to control thrombotic risk and potentially a broad range of other biology. Although generation of prostacyclin by fibroblasts has been shown previously, the scale and systemic activity was unappreciated. As such, this represents a basic change in our understanding and may provide new insight into how diseases of the lung result in cardiovascular risk.

Prostacyclin Mitigates Renal Fibrosis by Activating Fibroblast Prostaglandin I 2 Receptor.

SIGNIFICANCE STATEMENT: Renal fibrosis is a common pathologic process of progressive CKD. We have provided strong evidence that PGI 2 is an important component in the kidney injury/repairing process by reducing fibrosis and protecting renal function from declining. In our study, administration of a PGI 2 analog or selective PTGIR agonist after the acute injury ameliorated renal fibrosis. Our findings provide new insights into the role of PGI 2 in kidney biology and suggest that targeting PGI 2 /PTGIR may be a potential therapeutic strategy for CKD. BACKGROUND: Prostanoids have been demonstrated to be important modulators to maintain tissue homeostasis in response to physiologic or pathophysiologic stress. Prostacyclin (PGI 2 ) is a member of prostanoids. While limited studies have shown that PGI 2 is involved in the tissue injury/repairing process, its role in renal fibrosis and CKD progression requires further investigation. METHODS: Prostacyclin synthase ( Ptgis )-deficient mice, prostaglandin I 2 receptor ( Ptgir )-deficient mice, and an oral PGI 2 analog and selective PTGIR agonist were used to examine the role of PGI 2 in renal fibrosis in mouse models. We also analyzed the single-cell RNA-Seq data to examine the PTGIR -expressing cells in the kidneys of patients with CKD. RESULTS: Increased PTGIS expression has been observed in fibrotic kidneys in both humans and mice. Deletion of the PTGIS gene aggravated renal fibrosis and decline of renal function in murine models. A PGI 2 analog or PTGIR agonist that was administered after the acute injury ameliorated renal fibrosis. PTGIR, the PGI 2 receptor, deficiency blunted the protective effect of the PGI 2 analog. Fibroblasts and myofibroblasts were the major cell types expressing PTGIR in the kidneys of patients with CKD. Deletion of PTGIR in collagen-producing fibroblastic cells aggravated renal fibrosis. The protective effect of PGI 2 was associated with the inhibition of fibroblast activation through PTGIR-mediated signaling. CONCLUSIONS: PGI 2 is an important component in the kidney injury/repairing process by preventing the overactivation of fibroblasts during the repairing process and protecting the kidney from fibrosis and decline of renal function. Our findings suggest that PGI 2 /PTGIR is a potential therapeutic target for CKD.

Risk stratification for infection during immunosuppressive therapy in patients with lupus nephritis: A nested case-control study.

BACKGROUND: The current prediction models for the risk of infection during immunosuppressive treatment for lupus nephritis (LN) lack a prediction time window and have poor pertinence. This study aimed to develop a risk stratification to predict infection during immunosuppressive therapy in patients with LN. METHODS: This retrospective nested case-control study collected patients with LN treated with immunosuppressive therapy between 2014 and 2022 in the Nephrology ward in Huashan Hospital affiliated to Fudan University and Huashan Hospital Baoshan Branch. Cases were defined as patients who experienced infection during the follow-up period; patients were eligible as controls if they did not have infection during the follow-up period. RESULTS: There were 53 patients with infection by CTCAE V5.0 grade ≥2. According to the 1:3 nested matching, the 53 patients with infection were matched with 159 controls. In the multivariable logistic regression model, the change rate of fibrinogen (OR = 0.97, 95% CI: 0.94-0.99, p = 0.008), leukopenia (OR = 8.68, 95% CI: 1.16-301.72, p = 0.039), and reduced albumin (OR = 6.25, 95% CI: 1.38-28.24, p = 0.017) were independently associated with infection. The AUC of the ROC curve in the validation set of the multivariable logistic regression model in the internal random sampling was 0.864. The scores range from -2 to 10. The infection risk stratification ranges from 2.8% at score -2 to 97.5% at score 10. CONCLUSION: A risk stratification was built to predict the risk of infection in patients with LN undergoing immunosuppressive therapy.

Effectiveness and Safety of Spironolactone in the Treatment of IgA Nephropathy: A Retrospective Self-Controlled Study.

INTRODUCTION: It's crucial to utilize combination therapy for IgAN patients to reduce proteinuria and maintain stable kidney function. We demonstrate the safety and efficacy of low-dose spironolactone in management of IgAN patients. METHODS: Adult IgAN patients treated with spironolactone were evaluated. Patients were separated into two categories according to whether 24h-proteinuria was reduced by more than 20% after two-months of spironolactone treatment compared to baseline levels. RESULTS: 88 patients were analyzed and 24h-proteinuria decreased from 0.93g to 0.70 g (p＜0.001) after two-months of treatment with spironolactone, accompanied by a slight decrease in EPI-eGFR from 75.7 to 73.9 mL/min/1.73 m2 (p = 0.033). Intriguingly, 47 patients in effective MRA group showed less endocapillary hypercellularity (p = 0.040). In ineffective group, 18 patients discontinued MRA treatment because of 24h-proteinuria increased from 0.83 g to 1.04 g, while the other 23 patients were continued with spironolactone and proteinuria decreased to 0.57 g in the sixth month (p = 0.001). Furthermore, 12 patients with persistent high proteinuria during prednisone therapy, were added with spironolactone. 24-proteinuria were dropped from 0.95 g to 0.73 g at the second month, and to 0.50 g at the sixth month. CONCLUSIONS: In our study, we confirmed spironolactone's efficacy in reducing urine protein excretion in IgA nephropathy patients within two months of treatment. However, response varied among patients, with those showing endocapillary proliferation (E1) in renal biopsies having poor spironolactone responsiveness. Administering mineralocorticoid receptor antagonists (MRAs) to patients with eGFR over 30 ml/min did not result in hyperkalemia, indicating the treatment's safety. Key Words：IgA Nephrology, Proteinuria, Spironolactone, Renal function.

Knockout of the C3a receptor protects against renal ischemia reperfusion injury by reduction of NETs formation.

Renal ischemia/reperfusion (I/R) injury is a local sterile inflammatory response driven by innate immunity. Emerging data have revealed that complement and neutrophils contribute to hyperinflammation and oxidative stress in I/R induced acute kidney injury (AKI). However, the interplay between the C3a/C3aR axis and neutrophil extracellular traps (NETs) is imcompletelyunderstood. Here, we utilize genetically engineered mouse models and pharmacological inhibitors to investigate this association. The C3a/C3aR axis is found to promote neutrophil recruitment and NETs formation, thereby accelerating renal damage and dysfunction. Knockout of C3aR restores NETs release and improves renal function after I/R injury. Antibody-mediated blockade of NETs can also significantly ameliorate renal tubular injury and inflammation. Consistently, under stimulation by C3a, neutrophils are activated to promote NETs formation and subsequent renal tubular epithelial cell damage, and blocking C3aR rescued the injury. Interfering with reactive oxygen species (ROS) accumulation in neutrophils by antioxidant treatment significantly attenuates NETs formation. Our findings demonstrate that the C3a/C3aR-ROS-NETs axis constitutes a promising target for prevention or treatment of renal I/R injury.

Renal outcomes in IgA nephropathy following inactivated SARS-CoV-2 vaccination.

INTRODUCTION: There are increasing case reports on de novo or relapsing IgA nephropathy (IgAN) following SARS-CoV-2 vaccines, although the follow-up information on renal outcomes in IgAN patients post-SARS-CoV-2 vaccination is limited. In this study, we evaluated the renal outcomes of IgAN patients following inactivated vaccines. METHODS: We investigated the change in eGFR, proteinuria and hematuria in 113 primary IgAN patients post-vaccination. Worsening proteinuria was defined as an increase in proteinuria by more than 0.5 times and proteinuria > 1 g/d. Univariate and multivariable logistic regression analysis were used to evaluate possible predictors of worsening proteinuria. We then compared the renal outcomes of vaccinated patients after 6 months with 101 unvaccinated patients who were followed during the same period. RESULTS: A 2.54% (0.64, 8.61) decrease in renal function was observed in post-vaccination patients. Subgroup analysis revealed a significant decrease in eGFR in patients with 30 ≤ eGFR < 60 (mL/min/1.73 m2) post second SARS-CoV-2 dose (n = 18, p = 0.01). In addition, 10 individuals displayed worsening proteinuria post-vaccination, with the proteinuria subsequently ameliorating significantly after 6-month. Multivariate analysis showed that higher eGFR levels was an independent protective factor for worsening proteinuria. The renal outcome tended towards a decrease in eGFR in vaccinated patients after 6 months follow-up, although the difference was not significant (p = 0.06). CONCLUSION: Kidney function in IgAN patients tended to worsen after SARS-CoV-2 vaccination, particularly those with initial poor kidney function. This pattern of disease flare appears to be clinically mild, and further research is needed to determine whether the impact on kidney function is long-term.

Genome-Wide Association Study in Acute Tubulointerstitial Nephritis.

SIGNIFICANCE STATEMENT: Polymorphisms of HLA genes may confer susceptibility to acute tubulointerstitial nephritis (ATIN), but small sample sizes and candidate gene design have hindered their investigation. The first genome-wide association study of ATIN identified two significant loci, risk haplotype DRB1*14-DQA1*0101-DQB1*0503 (DR14 serotype) and protective haplotype DRB1*1501-DQA1*0102-DQB1*0602 (DR15 serotype), with amino acid position 60 in the peptide-binding groove P10 of HLA-DR ß 1 key. Risk alleles were shared among different causes of ATIN and HLA genotypes associated with kidney injury and immune therapy response. HLA alleles showed the strongest association. The findings suggest that a genetically conferred risk of immune dysregulation is part of the pathogenesis of ATIN. BACKGROUND: Acute tubulointerstitial nephritis (ATIN) is a rare immune-related disease, accounting for approximately 10% of patients with unexplained AKI. Previous elucidation of the relationship between genetic factors that contribute to its pathogenesis was hampered because of small sample sizes and candidate gene design. METHODS: We undertook the first two-stage genome-wide association study and meta-analysis involving 544 kidney biopsy-defined patients with ATIN and 2346 controls of Chinese ancestry. We conducted statistical fine-mapping analysis, provided functional annotations of significant variants, estimated single nucleotide polymorphism (SNP)-based heritability, and checked genotype and subphenotype correlations. RESULTS: Two genome-wide significant loci, rs35087390 of HLA-DQA1 ( P =3.01×10 -39 ) on 6p21.32 and rs2417771 of PLEKHA5 on 12p12.3 ( P =2.14×10 -8 ), emerged from the analysis. HLA imputation using two reference panels suggested that HLA-DRB1*14 mainly drives the HLA risk association . HLA-DRB1 residue 60 belonging to pocket P10 was the key amino acid position. The SNP-based heritability estimates with and without the HLA locus were 20.43% and 10.35%, respectively. Different clinical subphenotypes (drug-related or tubulointerstitial nephritis and uveitis syndrome) seemed to share the same risk alleles. However, the HLA risk genotype was associated with disease severity and response rate to immunosuppressive therapy. CONCLUSIONS: We identified two candidate genome regions associated with susceptibility to ATIN. The findings suggest that a genetically conferred risk of immune dysregulation is involved in the pathogenesis of ATIN.

Changes in the spectrum of biopsy-proven renal diseases over 11 years: a single-center study in China.

BACKGROUND: There have been some shifts in the frequency and distribution of biopsy-proven renal diseases in China over recent years. The aim of the study was to investigate the changing spectrum of renal diseases from the view of kidney biopsy data in a single center of China. METHODS AND RESULTS: A total of 10,996 cases of native renal biopsies from patients aged ≥15 years old in Huashan Hospital, Fudan University, between 2008 and 2018 were analyzed retrospectively. The results showed that primary glomerular nephropathy (PGN) remained the most common biopsy-proven renal disease (69.42% of total), with IgA nephropathy (IgAN) accounting for 44.40% of PGN, membranous nephropathy (MN) for 28.55%, minimal change disease (MCD) for 13.26% and focal segmental glomerulosclerosis (FSGS) for 8.00%. During the study period, the proportion of MN in PGN appeared an increasing tendency, while that of IgAN and MCD remained stable and that of FSGS showed a decline. Secondary glomerular nephropathy (SGN) constituted 21.54% of total cases, among which the leading two diseases were lupus nephritis (LN) and Henoch-Schonlein purpura nephritis (HSN) which accounted for 41.08% and 19.11% respectively. CONCLUSIONS: The 11-year retrospective study revealed that PGN was the predominant histologic diagnosis among patients undergoing renal biopsy and the most frequent type of PGN remained to be IgAN, followed by MN which increased dramatically.

Alpha 2-Heremans-Schmid glycoprotein gene polymorphism (rs4918) is associated with coronary artery calcification in incident peritoneal dialysis patients.

AIM: Coronary artery calcification (CAC) is a common and severe complication in peritoneal dialysis (PD) patients, and it progresses in a majority of patients. Fetuin-A, encoded by the alpha 2-Heremans-Schmid glycoprotein (AHSG) gene, is a serum calcification inhibitor. The study aimed to examine the role of AHSG gene polymorphism rs4918 in CAC and CAC progression of PD patients. METHODS: Incident PD patients at Huashan Hospital Fudan University in China from August 2007 to July 2018 were recruited in this prospective study and followed up for 2 years. Patients underwent CAC measurements at recruitment and 2 years later. AHSG gene polymorphism rs4918 and serum fetuin-A were determined at baseline. The demographic characteristics, clinical data, and laboratory data were collected during the follow-up period. Binary logistic regression was performed to explore the association between rs4918 with CAC and CAC progression. RESULTS: A total of 202 PD patients (112 men, 55.4%) were recruited, with a mean age of 54 ± 16 years. The multivariate logistic regression identified genotype GG as an independent risk factor that correlates to CAC (odds ratio [OR] = 2.153; 95% CI: 1.182-3.925; p = .012) and CAC progression (OR = 2.482; 95% CI: 1.422-4.330; p = .001). The serum fetuin-A level was influenced by the rs4918 variants of AHSG, with a dose-dependent effect depending on the number of the G allele. CONCLUSION: AHSG gene polymorphism rs4918 affects serum fetuin-A levels and is significantly associated with both CAC and CAC progression in a cohort of patients receiving PD.

Recurrent exercise-induced acute kidney injury associated with hypouricemia: a case report and literature review.

BACKGROUND: Hereditary renal hypouricemia (RHUC) is a heterogenous disorder characterized by defective uric acid (UA) reabsorption resulting in hypouricemia and increased fractional excretion of UA. RHUC is an important cause of exercise-induced acute kidney injury (EIAKI), nephrolithiasis and posterior reversible encephalopathy syndrome (PRES). We present here an unusual case of a patient with RHUC who presented with recurrent EIAKI and had two heterozygous mutations in the SLC2A9 gene. CASE PRESENTATION: A 43-year old man was admitted to our clinic because of bilateral loin pain, nausea and sleeplessness for 3 days after strenuous exercise. The laboratory results revealed increased levels of blood urea nitrogen (BUN) (15 mmol/l) and serum creatinine (Scr) (450 µmol/l), while the UA level was extremely low at 0.54 mg/dl, and his fractional excretion of urate (FE-UA) was 108%. The patient had an episode of acute kidney injury after playing soccer approximately 20 years ago, and on routine physical examination, his UA was less than 0.50 mg/dl. In view of the marked hypouricemia and high FE-UA, a diagnosis of RHUC was suspected, which led us to perform mutational screening of the SLC22A12 and SLC2A9 genes. DNA sequencing revealed no mutation in SLC22A12 gene, but two heterozygous mutations in the SLC2A9 gene. CONCLUSIONS: This is a rare report of a patient with RHUC2 due to the mutation of SLC2A9. And this unique symptom of EIAKI and decreased or normal serum concentrations of UA warrant more attention as an early cue of RHUC.

Functional iron deficiency anemia was associated with higher mortality in chronic kidney disease patients: the NHANES III follow-up study.

Anemia, a common complication of chronic kidney disease (CKD), is associated with poor prognosis. However, it is not completely clear whether this association is caused by anemia per se or other comorbidities. Whether different types of iron deficiency anemia can predict the outcomes of CKD remains unclear. The dataset from NHANES III was analyzed and Cox multivariate regression models and propensity score matching (PSM) method were used to evaluate the effect of anemia on mortality. Of 4103 patients with CKD, 14.6% had anemia. Among those with anemia, 38.8% had absolute iron deficiency (AID), and 19.8% had functional iron deficiency (FID). During the median follow-up time of 13.8 years, 2964 deaths and 804 cardiovascular deaths were observed. Anemia was robustly associated with a high risk of all-cause mortality in CKD patients after adjusting covariates by two multivariate regression models (Model 1: HR = 1.485, 95%CI:1.340-1.647, p < 0.001; Model 2: HR = 1.391, 95%CI:1.250-1.546, p < 0.001). In the PSM cohort, anemia was still an independent risk factor for all-cause mortality (Model 1: HR = 1.443, 95%CI: 1.256-1.656, p < 0.001; Model 2: HR = 1.357, 95%CI:1.177-1.564, p < 0.001). In the CKD population, anemia patients with FID had the highest risk of mortality than the other anemia groups (p < 0.05), while AID had a mortality rate similar to those without anemia (p > 0.05). In conclusion, anemia was associated with a worse prognosis in patients with CKD, which may be attributed to the higher mortality risk of FID rather than AID. AID wasn't associated with a higher mortality rate compared with CKD patients without anemia.

Plasma fibrinogen: a driver of left ventricular remodeling in patients undergoing peritoneal dialysis and its related risk factors.

BACKGROUND AND AIM: Plasma fibrinogen has been proven to be significantly associated with cardiovascular mortality in patients undergoing peritoneal dialysis (PD). The study aimed to investigate the role of fibrinogen in left ventricular (LV) remodeling and functions in patients on PD, and explore risk factors related to high fibrinogen level. METHODS: From February 2008 to July 2018, adult patients on regular PD for at least 1 month were recruited and followed up for two years. Correlation analysis was performed to explore the fibrinogen level and echocardiography measurements. Pathogenic factors correlated to the left ventricular hypertrophy (LVH) progression were explored by logistic regression models and the role of fibrinogen in it was verified by receiver operating characteristic (ROC) curves. Linear regression models were conducted to identify factors associated with fibrinogen level. RESULTS: A total of 278 patients undergoing PD (168 males, 60.4%) were recruited. Patients were trisected according to fibrinogen levels at baseline. Mean wall thickness (MWT), relative wall thickness (RWT), and left ventricular mass index (LVMI) were positively associated with fibrinogen level while E/A ratio was negatively associated with it. Multivariate logistic regression and ROC curve showed that fibrinogen was an independent risk factor for LVH progression. Multivariate linear regression analysis identified age, total cholesterol (CHO), fasting blood glucose (FBG), and high-sensitivity C-reactive protein (hsCRP) were significantly related to plasma fibrinogen level. CONCLUSIONS: An elevated fibrinogen level was independently associated with LVH progression in patients undergoing PD. Older age, higher level of FBG, CHO, and hsCRP were risk factors for elevated plasma fibrinogen level.

[Regulation of kidney on potassium balance and its clinical significance].

Virtually all of the dietary potassium intake is absorbed in the intestine, over 90% of which is excreted by the kidneys regarded as the most important organ of potassium excretion in the body. The renal excretion of potassium results primarily from the secretion of potassium by the principal cells in the aldosterone-sensitive distal nephron (ASDN), which is coupled to the reabsorption of Na+ by the epithelial Na+ channel (ENaC) located at the apical membrane of principal cells. When Na+ is transferred from the lumen into the cell by ENaC, the negativity in the lumen is relatively increased. K+ efflux, H+ efflux, and Cl- influx are the 3 pathways that respond to Na+ influx, that is, all these 3 pathways are coupled to Na+ influx. In general, Na+ influx is equal to the sum of K+ efflux, H+ efflux, and Cl- influx. Therefore, any alteration in Na+ influx, H+ efflux, or Cl- influx can affect K+ efflux, thereby affecting the renal K+ excretion. Firstly, Na+ influx is affected by the expression level of ENaC, which is mainly regulated by the aldosterone-mineralocorticoid receptor (MR) pathway. ENaC gain-of-function mutations (Liddle syndrome, also known as pseudohyperaldosteronism), MR gain-of-function mutations (Geller syndrome), increased aldosterone levels (primary/secondary hyperaldosteronism), and increased cortisol (Cushing syndrome) or deoxycorticosterone (hypercortisolism) which also activate MR, can lead to up-regulation of ENaC expression, and increased Na+ reabsorption, K+ excretion, as well as H+ excretion, clinically manifested as hypertension, hypokalemia and alkalosis. Conversely, ENaC inactivating mutations (pseudohypoaldosteronism type 1b), MR inactivating mutations (pseudohypoaldosteronism type 1a), or decreased aldosterone levels (hypoaldosteronism) can cause decreased reabsorption of Na+ and decreased excretion of both K+ and H+, clinically manifested as hypotension, hyperkalemia, and acidosis. The ENaC inhibitors amiloride and Triamterene can cause manifestations resembling pseudohypoaldosteronism type 1b; MR antagonist spironolactone causes manifestations similar to pseudohypoaldosteronism type 1a. Secondly, Na+ influx is regulated by the distal delivery of water and sodium. Therefore, when loss-of-function mutations in Na+-K+-2Cl- cotransporter (NKCC) expressed in the thick ascending limb of the loop and in Na+-Cl- cotransporter (NCC) expressed in the distal convoluted tubule (Bartter syndrome and Gitelman syndrome, respectively) occur, the distal delivery of water and sodium increases, followed by an increase in the reabsorption of Na+ by ENaC at the collecting duct, as well as increased excretion of K+ and H+, clinically manifested as hypokalemia and alkalosis. Loop diuretics acting as NKCC inhibitors and thiazide diuretics acting as NCC inhibitors can cause manifestations resembling Bartter syndrome and Gitelman syndrome, respectively. Conversely, when the distal delivery of water and sodium is reduced (e.g., Gordon syndrome, also known as pseudohypoaldosteronism type 2), it is manifested as hypertension, hyperkalemia, and acidosis. Finally, when the distal delivery of non-chloride anions increases (e.g., proximal renal tubular acidosis and congenital chloride-losing diarrhea), the influx of Cl- in the collecting duct decreases; or when the excretion of hydrogen ions by collecting duct intercalated cells is impaired (e.g., distal renal tubular acidosis), the efflux of H+ decreases. Both above conditions can lead to increased K+ secretion and hypokalemia. In this review, we focus on the regulatory mechanisms of renal potassium excretion and the corresponding diseases arising from dysregulation.

Disruption of mitochondrial complex III in cap mesenchyme but not in ureteric progenitors results in defective nephrogenesis associated with amino acid deficiency.

Oxidative metabolism in mitochondria regulates cellular differentiation and gene expression through intermediary metabolites and reactive oxygen species. Its role in kidney development and pathogenesis is not completely understood. Here we inactivated ubiquinone-binding protein QPC, a subunit of mitochondrial complex III, in two types of kidney progenitor cells to investigate the role of mitochondrial electron transport in kidney homeostasis. Inactivation of QPC in sine oculis-related homeobox 2 (SIX2)-expressing cap mesenchyme progenitors, which give rise to podocytes and all nephron segments except collecting ducts, resulted in perinatal death from severe kidney dysplasia. This was characterized by decreased proliferation of SIX2 progenitors and their failure to differentiate into kidney epithelium. QPC inactivation in cap mesenchyme progenitors induced activating transcription factor 4-mediated nutritional stress responses and was associated with a reduction in kidney tricarboxylic acid cycle metabolites and amino acid levels, which negatively impacted purine and pyrimidine synthesis. In contrast, QPC inactivation in ureteric tree epithelial cells, which give rise to the kidney collecting system, did not inhibit ureteric differentiation, and resulted in the development of functional kidneys that were smaller in size. Thus, our data demonstrate that mitochondrial oxidative metabolism is critical for the formation of cap mesenchyme-derived nephron segments but dispensable for formation of the kidney collecting system. Hence, our studies reveal compartment-specific needs for metabolic reprogramming during kidney development.

Roxadustat for Anemia in Patients with Kidney Disease Not Receiving Dialysis.

BACKGROUND: Roxadustat (FG-4592) is an oral inhibitor of hypoxia-inducible factor (HIF) prolyl hydroxylase that stimulates erythropoiesis and regulates iron metabolism. In phase 2 studies involving patients with chronic kidney disease, roxadustat increased levels of endogenous erythropoietin to within or near the physiologic range, along with increasing hemoglobin levels and improving iron homeostasis. Additional data are needed regarding the efficacy and safety of roxadustat for the treatment of anemia in patients with chronic kidney disease who are not undergoing dialysis. METHODS: In this phase 3 trial conducted at 29 sites in China, we randomly assigned 154 patients with chronic kidney disease in a 2:1 ratio to receive roxadustat or placebo three times a week for 8 weeks in a double-blind manner. All the patients had a hemoglobin level of 7.0 to 10.0 g per deciliter at baseline. The randomized phase of the trial was followed by an 18-week open-label period in which all the patients received roxadustat; parenteral iron was withheld. The primary end point was the mean change from baseline in the hemoglobin level, averaged over weeks 7 through 9. RESULTS: During the primary-analysis period, the mean (±SD) change from baseline in the hemoglobin level was an increase of 1.9±1.2 g per deciliter in the roxadustat group and a decrease of 0.4±0.8 g per deciliter in the placebo group (P<0.001). The mean reduction from baseline in the hepcidin level (associated with greater iron availability) was 56.14±63.40 ng per milliliter in the roxadustat group and 15.10±48.06 ng per milliliter in the placebo group. The reduction from baseline in the total cholesterol level was 40.6 mg per deciliter in the roxadustat group and 7.7 mg per deciliter in the placebo group. Hyperkalemia and metabolic acidosis occurred more frequently in the roxadustat group than in the placebo group. The efficacy of roxadustat in hemoglobin correction and maintenance was maintained during the 18-week open-label period. CONCLUSIONS: In Chinese patients with chronic kidney disease who were not undergoing dialysis, those in the roxadustat group had a higher mean hemoglobin level than those in the placebo group after 8 weeks. During the 18-week open-label phase of the trial, roxadustat was associated with continued efficacy. (Funded by FibroGen and FibroGen [China] Medical Technology Development; ClinicalTrials.gov number, NCT02652819.).

Roxadustat Treatment for Anemia in Patients Undergoing Long-Term Dialysis.

BACKGROUND: Roxadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that stimulates erythropoiesis and regulates iron metabolism. Additional data are needed regarding the effectiveness and safety of roxadustat as compared with standard therapy (epoetin alfa) for the treatment of anemia in patients undergoing dialysis. METHODS: In a trial conducted in China, we randomly assigned (in a 2:1 ratio) patients who had been undergoing dialysis and erythropoiesis-stimulating agent therapy with epoetin alfa for at least 6 weeks to receive roxadustat or epoetin alfa three times per week for 26 weeks. Parenteral iron was withheld except as rescue therapy. The primary end point was the mean change in hemoglobin level from baseline to the average level during weeks 23 through 27. Noninferiority of roxadustat would be established if the lower boundary of the two-sided 95% confidence interval for the difference between the values in the roxadustat group and epoetin alfa group was greater than or equal to -1.0 g per deciliter. Patients in each group had doses adjusted to reach a hemoglobin level of 10.0 to 12.0 g per deciliter. Safety was assessed by analysis of adverse events and clinical laboratory values. RESULTS: A total of 305 patients underwent randomization (204 in the roxadustat group and 101 in the epoetin alfa group), and 256 patients (162 and 94, respectively) completed the 26-week treatment period. The mean baseline hemoglobin level was 10.4 g per deciliter. Roxadustat led to a numerically greater mean (±SD) change in hemoglobin level from baseline to weeks 23 through 27 (0.7±1.1 g per deciliter) than epoetin alfa (0.5±1.0 g per deciliter) and was statistically noninferior (difference, 0.2±1.2 g per deciliter; 95% confidence interval [CI], -0.02 to 0.5). As compared with epoetin alfa, roxadustat increased the transferrin level (difference, 0.43 g per liter; 95% CI, 0.32 to 0.53), maintained the serum iron level (difference, 25 µg per deciliter; 95% CI, 17 to 33), and attenuated decreases in the transferrin saturation (difference, 4.2 percentage points; 95% CI, 1.5 to 6.9). At week 27, the decrease in total cholesterol was greater with roxadustat than with epoetin alfa (difference, -22 mg per deciliter; 95% CI, -29 to -16), as was the decrease in low-density lipoprotein cholesterol (difference, -18 mg per deciliter; 95% CI, -23 to -13). Roxadustat was associated with a mean reduction in hepcidin of 30.2 ng per milliliter (95% CI, -64.8 to -13.6), as compared with 2.3 ng per milliliter (95% CI, -51.6 to 6.2) in the epoetin alfa group. Hyperkalemia and upper respiratory infection occurred at a higher frequency in the roxadustat group, and hypertension occurred at a higher frequency in the epoetin alfa group. CONCLUSIONS: Oral roxadustat was noninferior to parenteral epoetin alfa as therapy for anemia in Chinese patients undergoing dialysis. (Funded by FibroGen and FibroGen [China] Medical Technology Development; ClinicalTrials.gov number, NCT02652806.).

Cyclooxygenase-2 contributes to diabetic nephropathy through glomerular EP4 receptor.

Diabetic nephropathy (DN) is a major microvascular complication of diabetes and the leading cause of mortality in diabetic patients. Cyclooxygenase (COX) and COX-derived prostanoids are documented to participate in the pathogenesis of diabetic nephropathy. Herein, we found an increased COX2 expression level in diabetic kidneys of STZ-induced DBA mice. The COX2 inhibitor significantly attenuated albuminuria and histological lesions, accompanied by up-regulation of the renal angiopoietin-1/tie-2 system. This finding is consistent with the presence of an angiogenic signature in endothelial cells during the development of DN. Prostaglandin E2 (PGE2) is the most abundant prostanoid in the kidney, and its receptor EP4 is expressed in the glomerulus, as determined by in situ hybridization. To test the hypothesis that diabetes-associated COX2 overexpression induces renal PGE2 production and endothelial dysfunction by activating glomerular EP4 receptors, the effect of an EP4 antagonist on Akita/DBA mice was investigated. Our results showed that blockade of EP4 receptor significantly reduced albuminuria in diabetic mice. Owing to the established adverse effect of COX2 inhibitors, our study provided new insight into meaningful renal benefits for diabetic nephropathy by targeting the EP4 receptor.

The Association between Baseline Serum Lipids and Mortality in Peritoneal Dialysis Patients.

INTRODUCTION: Lipid disturbances are common in ESRD patients. In peritoneal dialysis (PD) patients, dyslipidemia is even more common. This study aimed to examine whether serum lipids were associated with prognosis of PD patients. METHODS: Patients from a multicenter retrospective cohort were used for the present study. The primary endpoint was all-cause mortality. Cox regression was used to analyze the association between serum lipids including total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein, and triglycerides and the prognosis. RESULTS: The results showed that lower total cholesterol and LDL levels at the initiation of PD predicted higher all-cause mortality in PD patients. Multivariate analysis reveal that the association disappeared after adjusting for age, gender, albumin, prealbumin, protein catabolic rate normalized to body weight, C-reactive protein, and residual renal function. Further analysis showed that patients with lower total cholesterol/LDL had a higher mortality only during the first 24 months of follow-up. In the patients who survived >2 years after PD, lower total cholesterol/LDL was not associated with higher long-term all-cause mortality any more. CONCLUSION: Lower total cholesterol/LDL levels at the initiation of PD were associated with overall mortality in PD patients. The association could be potentially modified by malnutrition, inflammation, and residual renal function or disappeared after 24 months.

Mesangial cell-derived tenascin-C contributes to mesangial cell proliferation and matrix protein production in IgA nephropathy.

AIM: Tenascin-C (TNC), a non-structural extracellular matrix glycoprotein, is transiently expressed during development or after injury, playing an important role in injury and repair process. The potential role of TNC in the pathogenesis of IgA nephropathy (IgAN) remains to be clarified. METHODS: Immunohistochemistry staining for TNC was conducted on paraffin-embedded slices from renal biopsies of 107 IgAN patients, and correlation analysis was made between mesangial TNC expression and clinic-pathological parameters. In situ hybridization for TNC mRNA was further performed to figure out the cells that express TNC within glomeruli. In vitro experiments were also carried out on mouse mesangial cells (SV40 MES13) to elucidate the effect of TNC on mesangial cells. RESULTS: TNC was expressed in the mesangial area of IgAN, as well as in fibrotic regions. Correlation analysis showed that higher mesangial TNC was associated with higher level of proteinuria, lower estimated glomerular filtration rate and more serious pathological lesions (MEST score). In situ hybridization revealed that abundant TNC mRNA expression was observed in the affected glomeruli of IgAN, but not in minimal change disease. Moreover, TNC mRNA co-localized with PDGFRß mRNA, but not with PODXL mRNA, suggesting that TNC mRNA was expressed in the mesangial cells within glomeruli in IgAN. In vitro experiments showed that exogenous TNC promoted matrix protein production and mesangial cell proliferation, which was attenuated by an epidermal growth factor receptor inhibitor. CONCLUSION: Taken together, these results suggest that mesangial cell-derived TNC contributes to mesangial matrix expansion and mesangial cell proliferation, which is a potential therapeutic target in IgAN.

Prognostic values of left ventricular mass index progression in incident peritoneal dialysis patients : a prospective cohort study.

BACKGROUND: Left ventricular hypertrophy (LVH) is common among patients undergoing dialysis. However, the dynamic structural changes of LV are rarely discussed. The study aimed to investigate the prognostic significance of left ventricular mass index (LVMI)-progression in incident peritoneal dialysis (PD) patients, and explore risks factors for LVMI-progression. METHODS: Incident PD patients between February 2008 and July 2018 were recruited. Echocardiography was performed yearly to collect LVMI and evaluate its changes. Participants were divided into three subgroups: group with LVMI-regression, group with LVMI stable and group with LVMI-progression. The end points include all-cause mortality, cardiovascular mortality and cardiovascular events. Cox regression models were performed to identify the associations between LVMI-progression and these endpoints. Multivariate logistic regression was conducted to identify risk factors for LVMI-progression. RESULTS: A total of 216 PD patients (130 men,60.2%) with a mean age of 54.3 ± 16.8 years were recruited. LVMI-progression was identified in 72 patients (33.3%) after PD initiation. The cohort was followed for a median duration of 65.9 months. Multivariable Cox regression analysis revealed that LVMI-progression was an independent predictor of all-cause mortality (HR, 1.419; 95% CI, 1.016-1.982; p = 0.040), cardiovascular mortality (HR, 1.836; 95%CI, 1.084-3.108; p = 0.024), and cardiovascular events (HR, 1.494; 95%CI, 1.063-2.099; p = 0.021). Multivariable logistic regression showed that hemoglobin, ferritin, blood pressure and fibrinogen were significantly associated with LVMI-progression. CONCLUSION: Early LVMI-progression was independently associated with all-cause mortality and cardiovascular outcomes in PD patients. The dynamic monitoring of LVMI might therefore help identify high-risk patients.