Tubulointerstitial Injury Research Articles

Precision Medicine Proof-of-Concept Study of a TNF Inhibitor in FSGS and Treatment-Resistant Minimal Change Disease

Background: Focal segmental glomerulosclerosis (FSGS) and treatment-resistant minimal change disease (TR-MCD) are heterogeneous disorders with subgroups defined by distinct underlying mechanisms of glomerular and tubulointerstitial injury. A non-invasive urinary biomarker profile has been generated to identify patients with intra-kidney tumor necrosis factor (TNF)-activation and to predict response to anti-TNF treatment. We conducted this proof-of-concept, multi-center, open-label clinical trial to test the hypothesis that in patients with FSGS or TR-MCD and evidence of intra-renal TNF activation based on their biomarker profile, short-term treatment with adalimumab would reverse the elevated urinary excretion of MCP-1 and TIMP-1. Methods: Patients with FSGS or TR-MCD, eGFR>30 ml/min/1.73 m2, urine protein:creatinine ratio (UPCR) ≥1.5 g/g, and age 6-80 year were eligible for this trial. Adalimumab, 20-40 mg, was administered via subcutaneous injection, every 2 weeks for 5 doses. Participants were evaluated at weeks 0 (Baseline), 2, 8, and 10. Excretion of urinary (u) uMCP-1, uTIMP-1, uEGF, and plasma MCP-1 were measured at each visit. Results: Seven participants were enrolled, with median baseline UPCR 12.1 mg/mg (IQR: 2.2, 18.6), serum albumin 2.4 g/dL (IQR: 2.0, 2.8), and eGFR 57 mL/min/1.73 m2 (IQR: 44, 96). Based on self-report, they received all prescribed doses of adalimumab. The patients with the most favorable response based on the changes in urinary biomarkers had the best preserved kidney parenchyma based on uEGF excretion. Conclusions: Precision medicine trials are feasible in rare glomerular disorders. In this pilot study, adalimumab resulted in a heterogenous response of the candidate mechanistic-predictive biomarkers of TNF-mediated inflammation in patients with FSGS or TR-MCD. A reduction was seen in a subgroup of patients with preserved kidney parenchyma. The findings may reflect the challenge to reverse chronic injury at advanced stages of kidney disease or insufficient intra-renal target engagement with the intervention drug dose.

Diagnostic value of TRIM22 in diabetic kidney disease and its mechanism.

Diabetic kidney disease (DKD) is the primary reason of chronic kidney disease. Our objective was to discover potential autophagy-related biomarkers of tubulointerstitial injury in DKD and assess their clinical value. We retrieved four datasets (GSE104954, GSE30122, GSE30529, and GSE99340) of renal tubule samples from Gene Expression Omnibus (GEO) and used two algorithms (LASSO and SVM-RFE) to screen for autophagy-related differentially expressed genes (ARDEGs) in DKD. Tripartite motif containing 22 (TRIM22) was identified for subsequent validation. Validation of TRIM22 and autophagic indicators expression in clinical samples and HK-2 cells stimulated by high glucose using immunohistochemistry, immunofluorescence, and western blot. We identified four ARDEGs (TRIM22, PLK2, HTR2B, and FAS) using a diagnostic gene model. ROC curves further confirmed that TRIM22 had the best diagnostic efficacy for DKD. Both clinical samples and HK-2 cells stimulated by high glucose showed high protein expression of TRIM22. The correlation analysis revealed that TRIM22 correlates with SQSTM1, NGAL, and some clinical and pathological indicators in patients with DKD. We identified TRIM22 as a potential diagnostic biomarker for DKD, revealing its high diagnostic value in patients with DKD with moderate-to-severe interstitial fibrosis and tubular atrophy (IFTA). TRIM22 is involved in tubulointerstitial injury and autophagy dysregulation in DKD.

Tubulointerstitial injury in proteinuric chronic kidney diseases.

Proteinuria is an independent risk factor for chronic kidney disease progression and cardiovascular diseases. Apart from its prognostic role, the load of proteins that pass across the disrupted glomerular capillary wall trigger multiple pathophysiologic processes. These include, among others, intratubular complement activation and excessive proximal tubular reabsorption of filtered proteins, especially albumin and albumin-bound free fatty acids, which can set off several pathways of cellular damage. The activation of these pathways can cause apoptosis of proximal tubular cells and paracrine effects that incite the development of interstitial inflammation and fibrosis, ultimately leading to irreversible kidney injury. In this review, we provide a comprehensive overview of the current understanding on the mechanisms underlying the tubular toxicity of ultrafiltered proteins in the setting of proteinuric chronic kidney diseases. The acquired knowledge is expected to be instrumental for the development of novel therapeutic classes of medications to be tested on top of standard of care with optimized renin-angiotensin-aldosterone blockade and sodium-glucose cotransporter-2 inhibition, in order to further improve the clinical outcomes of patients with proteinuric chronic kidney diseases.

Deficiency of thiosulfate sulfurtransferase mediates the dysfunction of renal tubular mitochondrial fatty acid oxidation in diabetic kidney disease.

One of the main characteristics of diabetic kidney disease (DKD) is abnormal renal tubular fatty acid metabolism, especially defective fatty acid oxidation (FAO), accelerating tubular injury and tubulointerstitial fibrosis. Thiosulfate sulfurtransferase (TST), a mitochondrial enzyme essential for sulfur transfer, is reduced in metabolic diseases like diabetes and obesity. However, the potential role of TST in regulating fatty acid metabolic abnormalities in DKD remains unclear. Here, our data revealed decreased TST expression in the renal cortex of DKD patients. TST deficiency exacerbated tubular impairment in both diabetic and renal fibrosis mouse models, while sodium thiosulfate treatment or TST overexpression mitigated renal tubular injury with high-glucose exposure. TST downregulation mediated the decrease in S-sulfhydration of very long-chain specific acyl-CoA dehydrogenase, resulting in mitochondrial FAO dysfunction. This sequence of events exacerbates the progression of tubulointerstitial injury in DKD. Together, our findings demonstrate TST as a regulator of renal tubular injury in DKD.

Renal protective roles of macrophage matrix metalloproteinase-12 in mice with obstructed kidneys.

Matrix metalloproteinase (MMP)-12 has been reported to have diverse functions, including regulation of immune reactions and anti-inflammatory effects, but the potential roles of MMP-12 in kidney injury have not been fully elucidated. This study aimed to determine whether MMP-12 contributes to tubulointerstitial injury in a unilateral ureteric obstruction (UUO) model. MMP-12-deficient (MMP-12-/-) mice and C57BL/6J mice as controls (MMP-12+/+) were subjected to UUO and analysed 7 days after UUO. To analyse the functions of MMP-12 on monocytes/macrophages, we generated MMP-12-deficient, irradiated, chimeric mice (BM-MMP-12-/-) and performed UUO. Bone marrow-derived macrophages (BMDMs) were isolated from both groups of mice and used for investigations. MMP-12-/- mice showed exacerbation of macrophage accumulation and interstitial fibrosis in the UUO-kidney compared with control mice. BM-MMP-12-/- mice also showed exacerbation of kidney injury. UUO induced accumulation of Ly6C+ macrophages in MMP-12-/- mice compared with control mice. Increases in inflammatory cytokine (tumour necrosis factor α, interleukin [IL]-1β, IL-6) levels from BMDMs after lipopolysaccharide stimulation were higher in MMP-12-/- mice than in MMP-12+/+ mice. MMP-12 may play protective roles against kidney injury by UUO in mice, decreasing inflammatory cytokines from BMDMs and macrophage accumulation.

The Relationship between Circulating Kidney Injury Molecule-1 and Cardiovascular Morbidity and Mortality in Hemodialysis Patients.

The importance of identifying mortality biomarkers in chronic kidney disease (CKD), and especially in patients treated with hemodialysis (HD), has become evident. In addition to being a marker of tubulointerstitial injury, plasma kidney injury molecule-1 (KIM-1) has been mentioned in regard to HD patients as a risk marker for cardiovascular (CV) mortality and coronary artery calcification. The aim of this study was to assess the level of plasma KIM-1 as a marker of cardiovascular disease (CVD) and mortality in CKD5-HD patients (patients with CKD stage G5D treated with hemodialysis). We conducted a prospective case-control study that included 63 CKD5-HD patients (HD for 1-5 years) followed up for 48 months and a control group consisting of 52 non-dialysis patients diagnosed with CKD stages G1-G5 (ND-CKD). All patients had a CVD baseline assessment including medical history, echocardiography, and electrocardiography (ECG). Circulating plasma KIM-1 levels were determined with single-molecule counting immunoassay technology using an enzyme-linked immunosorbent assay. We obtained the following parameters: serum creatinine and urea; the inflammation markers CRP (C-reactive protein) and IL-6 (interleukin-6); and the anemia markers complete blood count, serum ferritin, and transferrin saturation (TSAT). The mean plasma KIM-1 level was 403.8 ± 546.8 pg/mL, showing a statistically significant correlation with inflammation (CRP, R = 0.28, p = 0.02; IL-6, R = 0.36, p = 0.005) and with anemia (hematocrit, R = -0.5, p = -0.0316; hemoglobin (Hb), R = -0.5, p = 0.02). We found that patients with left ventricular hypertrophy (LVH) on echocardiography (59.7%) had significantly lower mean levels of plasma KIM-1 than patients from the control group (155.51 vs. 432.12 pg/mL; p = 0.026). Regarding the patients' follow-up, we assessed all-cause mortality as an endpoint. After 24 months of follow-up, we found a mortality rate of 22.23%, while after 48 months, the mortality rate was 50.73%. A plasma KIM-1 level < 82.98 pg/mL was significantly associated with decreased survival in hemodialysis patients (p < 0.001). In patients treated with hemodialysis, low levels of plasma KIM-1 were associated with cardiovascular changes and an increased risk of mortality. Plasma KIM-1 levels were significantly higher in HD patients compared to ND-CKD patients.

Profiling dendritic cells subsets in renal tissue of patients with crescentic glomerulonephritis.

Dendritic cells (DCs) have been speculated to be involved in the pathogenesis of glomerular diseases. However, the numbers and distribution of DC subsets in the kidneys of patients with crescentic glomerulonephritis (CrGN) have not been clearly elucidated. A total of 26 patients with biopsy-proven CrGN were enrolled. Indirect immunofluorescence staining was used to quantify DC subsets in renal specimens. Double staining of HLA with CD11C, BDCA2 and CD209 respectively was performed to detect DC subsets. The correlation between DC subsets infiltrated in the kidney and clinical and pathological parameters was investigated. DC subsets were predominantly present in the kidney interstitium, particularly in the peri-glomerular area. The numbers of CD11C+DCs, BDCA2+DCs and CD209+DCs increased in the patients with CrGN and varied among different types of CrGN. Though significant correlation between DC subsets and the percentage of crescents had not been identified, a notable increase in the number of CD11C+DCs were observed with the chronic development of crescents. Furthermore, patients with severe tubulointerstitial injury exhibited significantly more infiltrations of CD11C+DCs, BDCA2+DCs and CD209+DCs. Moreover, the numbers of CD11C+DCs and BDCA2+DCs were found to correlate with the level of serum C3. Patients with CrGN showed increased kidney infiltration of DC subsets, primarily localized in the renal interstitium and peri-glomerular region. The correlation between DC subsets and fibrosis of crescent and severe tubulointerstitial injury implied a potential involvement of DCs in the development of CrGN.

Clinicopathological features and prognosis of IgA vasculitis nephritis with nephrotic-range proteinuria in children.

To investigate the clinical features, kidney pathology, treatment regimens, and clinical outcomes of IgA vasculitis nephritis (IgAVN) with nephrotic-range proteinuria in children. A retrospective review of children diagnosed with IgAVN between January 2019 and December 2022 was conducted. Participants were divided into two groups based on their urine protein/creatinine (UPCR) levels. Biodata, clinical characteristics, laboratory findings, pathologic features, treatment regimens, and outcomes were abstracted from case records and analyzed. A total of 255 children were identified, 94 with nephrotic-range proteinuria (UPCR ≥ 200 mg/mmol) and 161 with non-nephrotic proteinuria (UPCR < 200 mg/mmol). Patients in the nephrotic-range proteinuria group were significantly younger and had worse grades of glomerular and acute tubulointerstitial injury compared to those in the non-nephrotic proteinuria group. Higher levels of blood urea nitrogen (BUN), D-dimer (DD), and fibrin degradation products (FDP), and lower levels of total protein (TP), albumin (ALB), urine creatinine (Cr), prothrombin time (PT), activated partial thromboplastin time (APTT), IgG, CD3 + cells, and CD4 + cells were found in patients in the nephrotic-range proteinuria group. Clinical outcome of patients with nephrotic-range proteinuria was significantly associated with ISKDC grading, proportion of glomerular crescents and severity of acute tubulointerstitial injury. Children with nephrotic-range proteinuria exhibit more severe disordered immunologic function, hypercoagulability, glomerular and tubulointerstitial pathological damage, and have worse outcomes than those with lower proteinuria levels. Clinicians should pay great attention to the kidney injury and more extensive studies are required to identify optimal treatment regimens to improve outcomes in patients.

Glomerular Elasticity and Gene Expression Patterns Define Two Phases of Alport Nephropathy.

Early steps in glomerular injury are poorly understood in collagen IV nephropathies. We characterized structural, functional, and biophysical properties of glomerular capillaries and podocytes in Col4α3-/- mice and analyzed kidney cortex transcriptional profiles at various disease stages. We investigated the effects of TUDCA (suppresses ER stress) on these parameters and used human FSGS transcriptomic data to identify pathways rescued by TUDCA. In Col4α3-/- mice, podocyte injury develops by 3 months, with maximum glomerular deformability and 40% podocyte loss at 4 months. This period is followed is followed by glomerular capillary stiffening, proteinuria, reduced renal function, inflammatory infiltrates, and fibrosis. Bulk RNA sequencing at sequential time points revealed progressive increases in inflammatory and injury gene expression, and activation of the TNF pathway. Mapping Podocyte-enriched genes from FSGS patients to mice showed that TUDCA, which mitigated renal injury suppressed molecular pathways associated with podocyte stress, hypertrophy and tubulo-interstitial injury. Col4α3-/- nephropathy progresses in two phases. The first is characterized by podocytopathy, increased glomerular capillary deformability and accelerated podocyte loss, and the second by increased capillary wall stiffening and renal inflammatory and profibrotic pathway activation. The response of podocytes to TUDCA treatment provides insights into signaling pathways in Alport and related nephropathies.

Targeting Nrf2/HO-1 and NF-κB/TNF-α signaling pathways with empagliflozin protects against atrial fibrillation-induced acute kidney injury in rats

A bidirectional relationship exists between atrial fibrillation (AF) and kidney function. Uncontrolled AF may lead to kidney injury, whereas renal dysfunction may contribute to AF initiation and maintenance. This study aimed to investigate the protective effect of the sodium glucose cotransporter-2 inhibitor empagliflozin (EMPA) on acute kidney injury (AKI) associated with AF induced by acetylcholine and calcium chloride (ACh/CaCl2) in rats and elucidate the potential underlying mechanism. Rats were randomly divided as follows: control (CTRL) group: administered vehicles only; AF group: intravenously injected 1 ml/kg of an ACh/CaCl2 mixture for seven days to induce AF; EMPA group: orally administered EMPA (30 mg/kg) for seven days; AF+EMPA10 and AF+EMPA30 groups: co-administered the induction mixture and EMPA (10 and 30 mg/kg, respectively) for seven days. Our results showed that EMPA (10 and 30 mg/kg) effectively maintained kidney function and demonstrated a significant antioxidant potential. EMPA also suppressed AF-induced renal tubulointerstitial injury and fibrotic changes concurrently with reducing renal levels of the pro-inflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin-6, as well as the pro-fibrotic marker transforming growth factor beta-1 and collagen type I. Mechanistically, EMPA boosted nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) renal tissue expression while repressing nuclear factor kappa B (NF-κB) activation. In addition, these beneficial effects of EMPA on kidneys were concurrent with its ability to effectively inhibit AF-related electrocardiographic changes, reduce incidence and duration of AF episodes, and markedly suppress serum B-type natriuretic peptide and C-reactive protein levels. In conclusion, EMPA protected against AKI associated with AF induced by ACh/CaCl2 in rats through simultaneous modulation of the Nrf2/HO-1 and the NF-κB/TNF-α signaling pathways, exerting antioxidant, anti-inflammatory, and anti-fibrotic effects.

Identification of immune-associated biomarkers of diabetes nephropathy tubulointerstitial injury based on machine learning: a bioinformatics multi-chip integrated analysis

BackgroundDiabetic nephropathy (DN) is a major microvascular complication of diabetes and has become the leading cause of end-stage renal disease worldwide. A considerable number of DN patients have experienced irreversible end-stage renal disease progression due to the inability to diagnose the disease early. Therefore, reliable biomarkers that are helpful for early diagnosis and treatment are identified. The migration of immune cells to the kidney is considered to be a key step in the progression of DN-related vascular injury. Therefore, finding markers in this process may be more helpful for the early diagnosis and progression prediction of DN.MethodsThe gene chip data were retrieved from the GEO database using the search term ' diabetic nephropathy ‘. The ' limma ' software package was used to identify differentially expressed genes (DEGs) between DN and control samples. Gene set enrichment analysis (GSEA) was performed on genes obtained from the molecular characteristic database (MSigDB. The R package ‘WGCNA’ was used to identify gene modules associated with tubulointerstitial injury in DN, and it was crossed with immune-related DEGs to identify target genes. Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed on differentially expressed genes using the ‘ClusterProfiler’ software package in R. Three methods, least absolute shrinkage and selection operator (LASSO), support vector machine recursive feature elimination (SVM-RFE) and random forest (RF), were used to select immune-related biomarkers for diagnosis. We retrieved the tubulointerstitial dataset from the Nephroseq database to construct an external validation dataset. Unsupervised clustering analysis of the expression levels of immune-related biomarkers was performed using the ‘ConsensusClusterPlus ‘R software package. The urine of patients who visited Dongzhimen Hospital of Beijing University of Chinese Medicine from September 2021 to March 2023 was collected, and Elisa was used to detect the mRNA expression level of immune-related biomarkers in urine. Pearson correlation analysis was used to detect the effect of immune-related biomarker expression on renal function in DN patients.ResultsFour microarray datasets from the GEO database are included in the analysis : GSE30122, GSE47185, GSE99340 and GSE104954. These datasets included 63 DN patients and 55 healthy controls. A total of 9415 genes were detected in the data set. We found 153 differentially expressed immune-related genes, of which 112 genes were up-regulated, 41 genes were down-regulated, and 119 overlapping genes were identified. GO analysis showed that they were involved in various biological processes including leukocyte-mediated immunity. KEGG analysis showed that these target genes were mainly involved in the formation of phagosomes in Staphylococcus aureus infection. Among these 119 overlapping genes, machine learning results identified AGR2, CCR2, CEBPD, CISH, CX3CR1, DEFB1 and FSTL1 as potential tubulointerstitial immune-related biomarkers. External validation suggested that the above markers showed diagnostic efficacy in distinguishing DN patients from healthy controls. Clinical studies have shown that the expression of AGR2, CX3CR1 and FSTL1 in urine samples of DN patients is negatively correlated with GFR, the expression of CX3CR1 and FSTL1 in urine samples of DN is positively correlated with serum creatinine, while the expression of DEFB1 in urine samples of DN is negatively correlated with serum creatinine. In addition, the expression of CX3CR1 in DN urine samples was positively correlated with proteinuria, while the expression of DEFB1 in DN urine samples was negatively correlated with proteinuria. Finally, according to the level of proteinuria, DN patients were divided into nephrotic proteinuria group (n = 24) and subrenal proteinuria group. There were significant differences in urinary AGR2, CCR2 and DEFB1 between the two groups by unpaired t test (P < 0.05).ConclusionsOur study provides new insights into the role of immune-related biomarkers in DN tubulointerstitial injury and provides potential targets for early diagnosis and treatment of DN patients. Seven different genes ( AGR2, CCR2, CEBPD, CISH, CX3CR1, DEFB1, FSTL1 ), as promising sensitive biomarkers, may affect the progression of DN by regulating immune inflammatory response. However, further comprehensive studies are needed to fully understand their exact molecular mechanisms and functional pathways in DN.

Role of TSP-1 and its receptor ITGB3 in the renal tubulointerstitial injury of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS), a common cause of primary glomerulonephritis, has a poor prognosis and is pathologically featured by tubulointerstitial injury. Thrombospondin-1 (TSP-1) is an extracellular matrix protein that acts in combination with different receptors in the kidney. Here, we analyzed the tubular expression of TSP-1 and its receptor integrin β3 (ITGB3) in FSGS. Previously the renal interstitial chip analysis of FSGS patients with tubular interstitial injury showed that the expressions of TSP-1 and ITGB3 were up-regulated. We found that the level of TSP-1 and ITGB3 increased in the tubular cells of FSGS patients. The serum level of TSP-1 increased and was correlated to the degree of tubulointerstitial lesions in FSGS patients. THBS1/ITGB3 signaling induced renal tubular injury in HK-2 cells exposure to BSA and the ADR-induced nephropathy model. THBS1 knockout ameliorated tubular injury and renal fibrosis in ADR-treated mice. THBS1 knockdown decreased the expression of KIM-1 and caspase 3 in the HK-2 cells treated with BSA, while THBS1 overexpression could induce tubular injury. In vivo, we identified cyclo-RGDfK as an agent to block the binding of TSP-1 to ITGB3. Cyclo-RGDfK treatment could alleviate ADR-induced renal tubular injury and interstitial fibrosis in mice. Moreover, TSP-1 and ITGB3 were colocalized in tubular cells of FSGS patients and ADR-treated mice. Taken together, our data showed that TSP-1/ITGB3 signaling contributed to the development of renal tubulointerstitial injury in FSGS, potentially identifying a new therapeutic target for FSGS.

Role of the Anaphylatoxin Receptor C5aR2 in Angiotensin II-Induced Hypertension and Hypertensive End-Organ Damage.

Complement activation may facilitate hypertension through its effects on immune responses. The anaphylatoxin C5a, a major inflammatory effector, binds to the C5a receptors 1 and 2 (C5aR1, C5aR2). We have recently shown that C5aR1-/- mice have reduced hypertensive renal injury. The role of C5aR2 in hypertension is unknown. For examination of C5aR2 expression on infiltrating and resident renal cells a tandem dye Tomato-C5aR2 knock-in reporter mouse was used. Human C5aR2 expression was analyzed in a single-cell RNAseq data set from the kidneys of hypertensive patients. Finally, we examined the effect of angiotensin II-induced hypertension in C5aR2-deficient mice. Flow cytometric analysis of leukocytes isolated from kidneys of the reporter mice showed that dendritic cells are the major C5aR2-expressing population (34%) followed by monocyte/macrophages (30%) and neutrophils (14%). Using confocal microscopy C5aR2 was not detected in resident renal or cardiac cells. In the human kidney, C5aR2 was also mainly found in monocytes, macrophages, and dendritic cells with a significantly higher expression in hypertension (P < 0.05). Unilateral nephrectomy was performed followed by infusion of Ang II (0.75 ng/g/min) and a high salt diet in wildtype (n = 18) and C5aR2-deficient mice (n = 14). Blood pressure, renal injury (albuminuria, glomerular filtration rate, glomerular and tubulointerstitial injury, inflammation), and cardiac injury (cardiac fibrosis, heart weight, gene expression) did not differ between hypertensive wildtype and C5aR2-/- mice. In summary, C5aR2 is mainly expressed in myeloid cells in the kidney in mice and humans but its deficiency has no effect on Ang II-induced hypertensive injury.

Certain Red Yeast Rice Supplements in Japan Cause Acute Tubulointerstitial Injury

Certain Red Yeast Rice Supplements in Japan Cause Acute Tubulointerstitial Injury

EHHADH deficiency regulates pexophagy and accelerates tubulointerstitial injury in diabetic kidney disease

Peroxisomal l-bifunctional enzyme (EHHADH) plays a role in the classic peroxisomal fatty acid β-oxidation pathway; however, the relationship between EHHADH expression and diabetic kidney disease has not been well understood. Here, we found that endogenous EHHADH levels were strongly correlated with the progression and severity of diabetic nephropathy in T2D patients. EHHADH knockout mice exhibited worsened renal tubular injury in diabetic mice. Furthermore, EHHADH is a modulator of pexophagy. In renal tubular epithelial cells (RTECs) in vitro, the knockdown of EHHADH induced a dramatic loss of peroxisomes. The loss of peroxisomes in EHHADH-deficient RTECs was restored by either an autophagic inhibitor 3-methyladenine or bafilomycin A1 both in vitro and in vivo. NBR1 was required for pexophagy in EHHADH-knockdown cells, where the level of reactive oxygen species (ROS) was increased, while inhibition of ROS blocked pexophagy. In summary, our findings revealed EHHADH deficiency accelerated renal injury in DKD as a modulator of pexophagy.

Elucidating the substance basis and pharmacological mechanism of Fufang Qiling granules in modulating xanthine oxidase for intervention in hyperuricemia

Ethnopharmacological relevanceFufang Qiling granules (FQG), derived from the traditional Qiling Decoction with a longstanding clinical history, is utilized for the treatment of hyperuricemia (HUA). FQG is formulated with a combination of seven Chinese herbs based on the principles of traditional Chinese medicine (TCM) theories. Clinical evidence indicates that FQG exhibits favorable therapeutic effects in reducing uric acid (UA) levels and attenuating renal damage. Aim of this studyTo elucidate the potential active components and pharmacological mechanism of FQG in the treatment of HUA, and to provide an experimental basis for the development of efficient and low-toxicity TCM for HUA treatment. Materials and methodsA HUA rat model induced by potassium oxonate and adenine was established to initially evaluate the hypouricemic effects of FQG. Chemical analyses were conducted using an ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Network pharmacology was used to investigate the active components and mechanism of FQG in the treatment of HUA. Potential Xanthine oxidase (XOD) inhibitors were screened from FQG based on ultrafiltration liquid chromatography and mass spectrometry (UF-LC-MS). Molecular docking, surface plasmon resonance (SPR) and circular dichroism (CD) spectroscopy were applied to validate the interactions between the active components and XOD. ResultsIn comparison to the model group, treatment with FQG significantly decreased serum UA, serum creatinine (CREA), serum blood urea nitrogen (BUN), and liver XOD activity. Additionally, the FQG administration notably ameliorated HUA-induced renal injury in rats. Through the pharmacodynamics of the HUA rat models and network pharmacology, it was found that XOD was a key pathway enzyme in UA metabolism. 18 XOD inhibitors were screened from FQG by UF-LC-MS, and 11 compounds with strong affinity were verified by SPR, molecular docking and CD spectroscopy. ConclusionIn summary, flavonoids, organic acids and saponins may be the active components in FQG that alleviate HUA. The primary mechanism of FQG involves inhibiting XOD enzyme activity in the plasma to reduce UA production, alleviating renal tubular epithelial cell necrosis, tubulointerstitial injury, fibrosis, and urate deposition, ultimately exerting a therapeutic effect on HUA.

FTY720 ameliorates experimental MPO-ANCA-associated vasculitis by regulating fatty acid oxidation via the neutrophil PPARα-CPT1a pathway.

Increasing studies demonstrated the importance of C5a and anti-neutrophil cytoplasmic antibody (ANCA)-induced neutrophil activation in the pathogenesis of ANCA-associated vasculitis (AAV). Sphingosine-1-phosphate (S1P) acts as a downstream effector molecule of C5a and enhances neutrophil activation induced by C5a and ANCA. The current study investigated the role of a S1P receptor modulator, FTY720, in experimental autoimmune vasculitis (EAV) and explored the immunometabolism-related mechanisms of FTY720 in modulating ANCA-induced neutrophil activation. The effects of FTY720 in EAV were evaluated by quantifying haematuria, proteinuria, crescent formation, tubulointerstitial injury and pulmonary haemorrhage. RNA sequencing of renal cortex and gene enrichment analysis were performed. The proteins of key identified pathways were analysed in neutrophils isolated from peripheral blood of patients with active AAV and normal controls. We assessed the effects of FTY720 on ANCA-induced neutrophil respiratory burst and neutrophil extracellular traps formation (NETosis). FTY720 treatment significantly attenuated renal injury and pulmonary haemorrhage in EAV. RNA sequencing analyses of renal cortex demonstrated enhanced fatty acid oxidation (FAO) and peroxisome proliferator-activated receptor (PPAR) signalling in FTY720-treated rats. Compared with normal controls, patients with active AAV showed decreased FAO in neutrophils. FTY720-treated differentiated HL-60 cells showed increased expression of carnitine palmitoyltransferase 1a (CPT1a) and PPARα. Blocking or knockdown of CPT1a or PPARα in isolated human neutrophils and HL-60 cells reversed the inhibitory effects of FTY720 on ANCA-induced neutrophil respiratory burst and NETosis. FTY720 attenuated renal injury in EAV through upregulating FAO via the PPARα-CPT1a pathway in neutrophils, offering potential immunometabolic targets in AAV treatment.

Controversias en la fisiopatología de la hipertensión arterial.

Introduction: Purinergic receptors actively participate in the renal alterations in high blood pressure. The elevation of ATP in the renal interstitium activates purinergic receptors, constituting a fundamental pathway in the generation and persistence of arterial hypertension. Objective of the review: This article is a narrative review that aims to show the importance of new concepts in the pathophysiology of arterial hypertension. Essential points of the review: Purinergic receptors are ATP receptors; the more significant the ATP, the greater the purinergic receptors. Elevated ATP concentrations alter fundamental mechanisms related to blood pressure control, such as the pressure natriuresis mechanism and renal sodium excretion, the regulation of glomerular filtration, and the tubuloglomerular feedback mechanism. The alteration of these mechanisms decreases urinary sodium excretion. Whether influenced by genetic alterations or induced by vasoconstrictor peptides, a decrease in renal function and tubulointerstitial injury occur before the glomerulus is injured. The interaction between angiotensin II and purinergic receptors favors the progression of kidney damage. Conclusion: Kidney damage in high blood pressure is critical, so efforts should be made to control hypertension to prevent the progression of kidney damage that leads to kidney failure. To obtain better blood pressure control, developing purinergic receptor antagonists for clinical use is possible.

#245 Deficiency of GADD45α expression mediated tubulointerstitial injury in diabetic nephropathy

Abstract Background and Aims The tubulointerstitial injury plays crucial roles in the development of diabetic nephropathy (DN). Recently, some studies have reported that disorder of mitochondrial fatty acid β-oxidation in proximal tubules is involved in tubulointerstitial injury of DN. The growth arrest and DNA damage-inducible gene 45 (GADD45) family proteins, especially, GADD45α, plays a crucial role in various cellular processes, such as mitochondrial biogenesis and lipid metabolism. Recent studies have demonstrated that GADD45α facilitates gene activation by inducing DNA demethylation. Therefore, this study aimed to investigate the role of GADD45α in tubulointerstitial injury of DN and its underlying mechanisms. Methods Bioinformatics and machine learning techniques were employed to identify differentially expressed genes between healthy individuals and DN patients. Experiments were conducted by using high glucose-treated HK-2 cells and streptozotocin (STZ)-induced mice. Lentivirus carrying the GADD45α gene was used to induce GADD45α overexpression in HK-2 cells. Adeno-Associated Virus vectors carrying LoxP-flanked GADD45α were intravenously injected into γGT-Cre transgenic mice expressing Cre recombinase in renal proximal tubular cells, specifically leading to GADD45α overexpression in proximal tubules. Results Through bioinformatics and machine learning techniques, GADD45α was identified and found to exhibit a strong association with tubulointerstitial injury in DN. Further analysis revealed that the expression of GADD45α was decreased in the kidneys of DN patients, diabetic mice, and high glucose-treated HK-2 cells. Notably, GADD45α overexpression ameliorated kidney damage and mitochondrial injury, leading to improved fatty acid β-oxidation, restored ATP production, and reduced ROS production. Transcriptomics analyses further demonstrated that GADD45α overexpression enhanced the expression of genes related to mitochondrial biogenesis, dynamics, and electron transport chain, with six transmembrane epithelial antigen of prostate 4 (STEAP4) being a key protein in this process. Knocking down STEAP4 using siRNA in HK-2 cells exacerbated the damage induced by high glucose. In addition, our further results indicated that high glucose increased methylation of the STEAP4 promoter, while GADD45α overexpression decreased methylation and increased STEAP4 expression. Conclusions Deficiency of GADD45α expression mediated tubulointerstitial injury in DN, which was mainly through the decreased STEAP4 expression by demethylating CpG motifs in the STEAP4 promoter region, thereby resulting in reduced fatty acid oxidation, energy synthesis, and increased ROS production, and finally accelerated tubular injuries. These findings suggested that targeting the GADD45α-STEAP4 pathway could be a potential therapeutic strategy for DN.

#68 Novel clinical application of urinary angiotensin-converting enzyme assay in renal sarcoidosis: a retrospective observational study

Abstract Background and Aims Renal manifestations of sarcoidosis are observed in approximately 1–5% and characterized mainly by granulomatous interstitial nephritis, which could lead to kidney failure. Angiotensin-converting enzyme (ACE) reflects the presence of granuloma; hence, serum ACE and tubular injury markers are measured in renal sarcoidosis (RS); however, they either have low sensitivity or low specificity. Although its practicality has not been established, the use of ACE levels in cerebrospinal fluid has been reported for neuro-sarcoidosis. Therefore, we hypothesized that urinary ACE could reflect granuloma presence in the kidneys and could be a disease-specific marker for RS. Method This was a single-center, retrospective observational study. We evaluated clinical characteristics and kidney biopsy findings from electronic medical record surveys and kidney biopsy specimens. The control groups included sarcoidosis without renal involvement (SAR-control) and tubulointerstitial nephritis without a sarcoidosis etiology (TIN-control). Serum and urinary ACE levels were measured, and urinary fractional excretion of ACE (FEACE) was investigated. Serum ACE assay and urinary ACE levels were measured using the colorimetric method with p-hydroxybenzoyl-glycyl-L-histidyl-L-leucine. A total of six patients (three with RS; one with sarcoidosis as controls; and two with TIN controls) with undetectable urinary ACE levels were excluded from the urinary ACE and FEACE analyses. Tubulointerstitial lesions were visually assessed for essentially normal (%), inflammatory cell infiltrates (%), tubular atrophy (%), and interstitial fibrosis (%) by several board-certified nephrologists, and analyzed the correlation of these lesions with each marker. Results This study included 18 patients with RS, 18 as SAR-control, and 10 as TIN-control. Serum ACE, urinary ACE, and FEACE levels in the RS group were significantly higher than those in the control groups. Receiver operating characteristic analysis identified FEACE and serum ACE levels as useful biomarkers for diagnosing RS among patients with both controls, respectively. In the RS group, FEACE was positively correlated with the degree of tubulointerstitial injury (r = 0.69, P = 0.0045), and the cutoff value of FEACE for diffuse tubulointerstitial injury (50.0% or more) was 0.39%, with a sensitivity and specificity of 100.0%. Furthermore, obvious positive correlations were observed among FEACE, inflammatory cell infiltrates (r = 0.53, P = 0.044), and interstitial fibrosis (r = 0.56, P = 0.029) in the RS group but not in the TIN-control. Conclusion Combination with serum and urinary ACE could help diagnose and assess disease severity among patients with RS.