Tubulointerstitial Damage Research Articles

Evaluation of renal tubulointerstitial damage as a residual renal risk factor for adverse cardiac events in patients with aortic valve stenosis

Abstract Background Renal dysfunction, defined as a lower eGFR, has been shown to be related to cardiovascular events in patients with aortic stenosis treated with transcatheter aortic valve implantation (TAVI). However, the contribution of renal tubulointerstitial damage to the predictive value for cardiovascular events remains unclear. The aim of this study was to elucidate whether renal tubulointerstitial damage is associated with the occurrence of all death and heart failure patients who have had TAVI. Methods and results In a cohort of 155 patients, urinary beta2-microglobulin (beta2MG) levels were measured. Patients were monitored for less than three years or until experiencing all-cause mortality or hospitalization due to heart failure. The cumulative all-cause mortality was 11.5%, and heart failure admission rate stood at 5.4%. Stratifying outcomes by beta2MG levels revealed significantly lower rates of all-cause mortality and heart failure in patients with beta2MG <0.20 mg/gCre compared to those with beta2MG ≥0.20 mg/gCre (10.2% versus 24.2%, p=0.01). When outcomes were stratified according to the beta2MG levels in combination with eGFR levels, Kaplan-Meier analyses showed that all-cause mortality and heart failure rates increased depending on an increase in the beta2MG levels (p<0.05) even if eGFR is above 60 ml/min. Moreover, multivariate Cox analyses revealed that high levels of beta2MG were an independent predictor of adverse events. Conclusion Renal tubulointerstitial damage is associated with the occurrence of all death and hospitalization for heart failure independent of renal glomerular function.

β-Mangostin Alleviates Renal Tubulointerstitial Fibrosis via the TGF-β1/JNK Signaling Pathway.

The epithelial-to-mesenchymal transition (EMT) plays a key role in the pathogenesis of kidney fibrosis, and kidney fibrosis is associated with an adverse renal prognosis. Beta-mangostin (β-Mag) is a xanthone derivative obtained from mangosteens that is involved in the generation of antifibrotic and anti-oxidation effects. The purpose of this study was to examine the effects of β-Mag on renal tubulointerstitial fibrosis both in vivo and in vitro and the corresponding mechanisms involved. As shown through an in vivo study conducted on a unilateral ureteral obstruction mouse model, oral β-Mag administration, in a dose-dependent manner, caused a lesser degree of tubulointerstitial damage, diminished collagen I fiber deposition, and the depressed expression of fibrotic markers (collagen I, α-SMA) and EMT markers (N-cadherin, Vimentin, Snail, and Slug) in the UUO kidney tissues. The in vitro part of this research revealed that β-Mag, when co-treated with transforming growth factor-β1 (TGF-β1), decreased cell motility and downregulated the EMT (in relation to Vimentin, Snail, and N-cadherin) and phosphoryl-JNK1/2/Smad2/Smad3 expression. Furthermore, β-Mag co-treated with SB (Smad2/3 kinase inhibitor) or SP600125 (JNK kinase inhibitor) significantly inhibited the TGF-β1-associated downstream phosphorylation and activation of JNK1/2-mediated Smad2 targeting the Snail/Vimentin axis. To conclude, β-Mag protects against EMT and kidney fibrotic processes by mediating the TGF-β1/JNK/Smad2 targeting Snail-mediated Vimentin expression and may have therapeutic implications for renal tubulointerstitial fibrosis.

The mechanosensitive ion channel Piezo1 contributes to podocyte cytoskeleton remodeling and development of proteinuria in lupus nephritis.

Piezo1 functions as a special transducer of mechanostress into electrochemical signals and is implicated in the pathogenesis of various diseases across different disciplines. However, whether Piezo1 contributes to the pathogenesis of lupus nephritis (LN) remains elusive. To study this, we applied an agonist and antagonist of Piezo1 to treat lupus-prone MRL/lpr mice. Additionally, a podocyte-specific Piezo1 knockout mouse model was also generated to substantiate the role of Piezo1 in podocyte injury induced by pristane, a murine model of LN. A marked upregulation of Piezo1 was found in podocytes in both human and murine LN. The Piezo1 antagonist, GsMTx4, significantly alleviated glomerulonephritis and tubulointerstitial damage, improved kidney function, decreased proteinuria, and mitigated podocyte foot process effacement in MRL/lpr mice. Moreover, podocyte-specific Piezo1 deletion showed protective effects on the progression of proteinuria and podocyte foot process effacement in the murine LN model. Mechanistically, Piezo1 expression was upregulated by inflammatory cytokines (IL-6, TNF-α and IFN-γ), soluble urokinase Plasminogen Activator Receptor and its own activation. Activation of Piezo1 elicited calcium influx, which subsequently enhanced Rac1 activity and increased active paxillin, thereby promoting cytoskeleton remodeling and decreasing podocyte motility. Thus, our work demonstrated that Piezo1 contributed to podocyte injury and proteinuria progression in LN. Hence, targeted therapy aimed at decreasing or inhibiting Piezo1 could represent a novel strategy to treat LN.

Progressive Tubulointerstitial Damage through Constitutive Activation of the NF-kB Pathway in Renin Lineage Cells

Progressive Tubulointerstitial Damage through Constitutive Activation of the NF-kB Pathway in Renin Lineage Cells

Renal structural changes and apelin receptor expression in spontaneously hypertensive rats: implications for hypertension-induced kidney injury.

Arterial hypertension is a primary risk factor for kidney disease. Recent advances have implied a potential link between the apelin system and renal homeostasis. We used 6- and 12-month-old spontaneously hypertensive rats and age-matched normotensive controls to assess the changes in the renal expression of the apelin receptor by immunohistochemical method. The study also evaluated correlations between the renal apelin receptor's expression and renal injury indicators. The histological analysis showed elevated glomerular sclerosis and tubulointerstitial damage indices in both groups of hypertensive rats compared to age-matched controls. Older rats within each group exhibited higher scores than younger ones. The immunohistochemical analysis revealed varying apelin receptor expression patterns, with tubular expression intensifying both with hypertension severity and age. Glomerular expression was notably higher in older hypertensive rats compared to normotensive controls. We reported significant positive correlations between glomerular apelin receptor expression and glomerular sclerosis index in older hypertensive animals. Similarly, a positive correlation between tubular apelin receptor expression and tubulointerstitial damage index was discovered in hypertensive rats, suggesting hypertension-related changes in apelin receptor expression and renal damage. Our study found kidney changes and varying apelin receptor correlations in hypertensive rat kidneys, suggesting complex roles needing research.

Autosomal Dominant Tubulointerstitial Kidney Disease–UMOD: A Monogenic Renal Disease that Cannot Be Ignored

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a group of monogenic renal diseases characterized by autosomal dominant inheritance and progressive tubulointerstitial damage with bland urinary sediment. With the discovery of pathogenic variants, ADTKD was recognized as the most frequent non-polycystic genetic kidney disease. ADTKD–UMOD is caused by pathogenic variants of UMOD (coding gene of uromodulin) and is the most common subtype of ADTKD. With the improved awareness of the disease and the advance of genetic testing technology, cohort studies on affected families have gradually increased and deepened our understanding of the clinical and genetic spectrum of ADTKD–UMOD. In addition, extensive research has been conducted on the pathogenetic mechanism. This review highlights recent research progress in the genetic and clinical spectrum, as well as the underlying mechanisms of ADTKD–UMOD.

Purinergic Receptor Antagonists: A Complementary Treatment for Hypertension.

The treatment of hypertension has improved in the last century; attention has been directed to restoring several altered pathophysiological mechanisms. However, regardless of the current treatments, it is difficult to control blood pressure. Uncontrolled hypertension is responsible for several cardiovascular complications, such as chronic renal failure, which is frequently observed in hypertensive patients. Therefore, new approaches that may improve the control of arterial blood pressure should be considered to prevent serious cardiovascular disorders. The contribution of purinergic receptors has been acknowledged in the pathophysiology of hypertension; this review describes the participation of these receptors in the alteration of kidney function in hypertension. Elevated interstitial ATP concentrations are essential for the activation of renal purinergic receptors; this becomes a fundamental pathway that leads to the development and maintenance of hypertension. High ATP levels modify essential mechanisms implicated in the long-term control of blood pressure, such as pressure natriuresis, the autoregulation of the glomerular filtration rate and renal blood flow, and tubuloglomerular feedback responses. Any alteration in these mechanisms decreases sodium excretion. ATP stimulates the release of vasoactive substances, causes renal function to decline, and induces tubulointerstitial damage. At the same time, a deleterious interaction involving angiotensin II and purinergic receptors leads to the deterioration of renal function.

Clinical manifestations and renal pathology of ethylene glycol.

Ethylene glycol (EG) poisoning is a critical medical emergency often associated with suicide attempts in adults. EG is metabolized by alcohol dehydrogenase, leading to the formation of toxic metabolites that cause metabolic acidosis, renal failure, hypocalcemia, aciduria, and disorders of the central nervous and cardiovascular systems. Calcium oxalate, a metabolite of EG, contributes to acute tubular necrosis. Despite limited reports on human renal pathology, we present a case detailing renal pathology following EG ingestion. A 44-year-old male, admitted due to loss of consciousness, had ingested a lethal dose of EG. Blood tests indicated metabolic acidosis, while urinary examination revealed calcium oxalate crystals. Continuous renal replacement therapy corrected the acidosis; however, nephrogenic diabetes insipidus subsequently developed. A renal biopsy on day 31 revealed calcium oxalate crystal deposition and tubulointerstitial damage. Notably, various stages of crystal deposition, adherence, and degradation were observed. This case underscores the importance of considering EG poisoning in cases of unexplained metabolic acidosis and renal dysfunction, with renal biopsy serving as a valuable diagnostic tool. Understanding the renal effects of EG is essential for timely intervention and effective management of poisoning cases.

Unusual course of glyphosate-induced acute kidney injury: a case report of tubulointerstitial nephritis treated with steroids.

Glyphosate is a widely used herbicide that is generally considered safe; however, acute kidney injury (AKI) caused by glyphosate ingestion can be severe and require hemodialysis. We present a unique case of a 68-year-old Japanese man who developed AKI after accidental ingestion of glyphosate and required hemodialysis. Based on the clinical presentation and findings, the patient was diagnosed with renal AKI with severe tubulointerstitial damage. However, the precise pathogenesis of the tubulointerstitial damage remained unclear. An elevated beta-2 microglobulin level discovered by the urinalysis during admission raised the suspicion of tubulointerstitial nephritis caused by glyphosate. Gallium scintigraphy revealed accumulation in both kidneys. A renal biopsy revealed acute tubulointerstitial nephritis rather than acute tubular necrosis, which is commonly observed with glyphosate-induced renal injury. After initiating steroid therapy, his kidney function gradually improved and he was weaned from hemodialysis. This report is the first to describe glyphosate-induced acute tubulointerstitial nephritis that was successfully treated with immunosuppressive therapy. Furthermore, this report highlights the importance of steroid therapy for cases of persistent kidney injury after the discontinuation of agents associated with acute tubulointerstitial nephritis.

Renal ischemia/reperfusion induces prominent progressive kidney disease in diabetic mice.

Acute kidney injury (AKI) is a public health concern associated with high rates of mortality, even in milder cases. One of the reasons for the difficulty in managing AKI in patients is due to its association with pre-existing comorbidities, such as diabetes. In fact, diabetes increases the susceptibility to develop more severe AKI after renal ischemia. However, the long-term effects of this association are not known. Thus, an experimental model was designed to evaluate the chronic effects of renal ischemia/reperfusion (IR) in streptozotocin (STZ)-treated mice. We focused on the glomerular and tubulointerstitial damage, as well as kidney function and metabolic profile. It was found that pre-existing diabetes may potentiate progressive kidney disease after AKI, mainly by exacerbating proinflammatory and sustaining fibrotic responses and altering renal glucose metabolism. To our knowledge, this is the first report that highlights the long-term effects of renal IR on diabetes. The findings of this study can support the management of AKI in clinical practice.NEW & NOTEWORTHY This study demonstrated that early diabetes potentiates progressive kidney disease after ischemia/reperfusion (IR)-induced acute kidney injury, mainly by exacerbating pro-inflammatory and sustaining fibrotic responses and altering renal glucose metabolism. Thus, these findings will contribute to the therapeutic support of patients with type 1 diabetes with eventual renal IR intervention in clinical practice.

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.

Species-specific histological characterizations of renal tubules and collecting ducts in the kidneys of cats and dogs.

The histomorphological features of normal kidneys in cats and dogs have been revealed despite the high susceptibility of cats to tubulointerstitial damage. Herein, the histological characteristics of the two species were compared. Cytoplasmic lipid droplets (LDs) were abundant in the proximal convoluted tubules (PCTs) of cats aged 23-27 months but scarce in dogs aged 24-27 months. LDs were rarely observed in the distal tubules (DTs) and collecting ducts (CDs) of either species, as visualized by the expression of Tamm-Horsfall protein 1, calbindin-D28K, and aquaporin 2. The occupational area ratio of proximal tubules (PTs) in the renal cortex was higher, but that of DTs or CDs was significantly lower in adult cats than in dogs. Single PT epithelial cells were larger, but PCT, DT, and CD lumens were significantly narrower in adult cats than in dogs. Unlike adults, young cats at 6 months exhibited significantly abundant cytoplasmic LDs in proximal straight tubules, indicating lipid metabolism-related development. Histochemistry of the 21 lectins also revealed variations in glycosylation across different renal tubules and CDs in both species. Sodium-glucose cotransporter 2 was expressed only in PTs, excluding the proximal straight tubules with few LDs in adult cats or the PCTs of young cats and adult dogs. These findings are crucial for understanding species-specific characteristics of renal histomorphology and pathogenesis.

Sodium tungstate (NaW) decreases inflammation and renal fibrosis in diabetic nephropathy

BackgroundDiabetic Nephropathy is one of the most severe complications of Diabetes Mellitus and the main cause of end-stage kidney disease worldwide. Despite the therapies available to control blood glucose and blood pressure, many patients continue to suffer from progressive kidney damage. Chronic hyperglycemia is the main driver of changes observed in diabetes; however, it was recently discovered that inflammation and oxidative stress contribute to the development and progression of kidney damage. Therefore, it is important to search for new pharmacological therapies that stop the progression of DN. Sodium tungstate (NaW) is an effective short and long-term antidiabetic agent in both type 1 and type 2 diabetes models. MethodsIn this study, the effect of NaW on proinflammatory signalling pathways, proinflammatory proteins and fibrosis in the streptozotocin (STZ)-induced type 1 diabetic rat model was analysed using histological analysis, western blotting and immunohistochemistry. ResultsNaW treatment in diabetic rats normalize parameters such as glycemia, glucosuria, albuminuria/creatinuria, glomerular damage, and tubulointerstitial damage. NaW decreased the proinflammatory signaling pathway NF-κB, inflammatory markers (ICAM-1, MCP-1 and OPN), profibrotic pathways (TGFβ1/Smad2/3), reduced epithelial-mesenchymal transition (α -SMA), and decreased renal fibrosis (type IV collagen). ConclusionNaW could be an effective drug therapy for treating human diabetic nephropathy.

Маркеры повреждения почек в моче у пациентов с фибрилляцией предсердий и хронической болезнью почек, принимающих ривароксабан (результаты проспективного наблюдения)

To assess the urinary markers of podocytic (nephrin) and tubulointerstitial damage (NGAL, KIM-1, albuminuria) levels in patients with atrial fibrillation (AF) and chronic kidney disease (CKD) stages 3 and 4 and to evaluate their relationship with bleedings during rivaroxaban treatment.

#412 Influence of SGLT2I on tubulointerstitium in DKD patients with moderate renal dysfunction

Abstract Background and Aims In the FAGOTTO study (jRCTs041200069) to evaluate changes of renal hemodynamics on initial glomerular filtration rate (GFR) dip induced by Sodium-glucose cotransporter 2 inhibitors (SGLT2i) in patients (pts) with type 2 diabetic kidney disease (DKD) and moderate renal dysfunction, we reported that SGLT2 inhibition maintained the levels of glomerular filtration fraction (FF) and renal vascular resistance (RVR) during decrease in GFR as well as renal plasma and blood flow. In this sub analysis, we evaluated if GFR dip by SGLT2i might induce tubulointerstitial disorder by measuring urinary biomarkers. Method The FAGOTTO study was a 12-week multicenter, open-label, randomized (1:1), parallel-group study treated with Canagliflozin (Group CA) or control groups (Group CO) in DKD pts with 30 ≤ estimated GFR (eGFR) ≤ 60 mL/min/1.73 m2. Urinary biomarkers including liver-type fatty-acid binding protein (L-FABP), N-acetyl-glucosaminidase (NAG), β2-microglobulin (β2MG) and monocyte chemoattractant protein-1 (MCP-1) were measured at baseline, 4 weeks and 12 weeks after start of the trial. The adjusted mean and SE for changes were calculated at each time point by a linear mixed model with baseline values, time point, and interaction of the treatment group as the fixed effects. We compared these changes between treatment the groups the Tukey-Kramer method to correct for multiplicity. Results The adjusted mean changes in L-FABP at the 4-week and 12-week time point after trial start were estimated −0.35 and −0.17 μg/gCr in Group CA and 0.06 and 1.23 μg/gCr in Group CO in a linear mixed model, respectively. Similarly, the changes were estimated 2.63 and 3.71 U/gCr in Group CA and 1.38 and −1.21 U/gCr in Group CO in NAG, 317.7 and 291.4 μg/gCr in Group CA and 416.6 and 375.1 μg/gCr in Group CO in β2MG and 19.6 and 64.6 pg/gCr in Group CA and −7.7 and −2.7 pg/gCr in Group CO in MCP-1, respectively. When compared the changes in L-FABP, NAG, β2MG and MCP-1 between Group Ca and Group Co by Tukey-Kramer multiple-comparison test, there were no significant differences in any biomarkers. (Figure). Conclusion In this analysis, no significant difference in any of these biomarkers was detected in Group CA compared to those in Group CO at 4 weeks and 12 weeks after administration of SGLT2i. Although further studies should be needed to conclude, transient decrease in GFR after administration of SGLT2i might not be involved with tubulointerstitial damage and our study gives one evidence as a safety information in use of SGLT2i to DKD pts with moderate renal dysfunction.

#553 Renal tubular damage is an independent risk factor for all-cause and cardiovascular mortality in a community-based population: the Takahata Study

Abstract Background and Aims Renal tubulointerstitial damage is a risk for renal failure. However, the association between renal tubulointerstitial damage and all-cause and cardiovascular mortality in the general population remains unclear. In this prospective cohort study, we examined this point using urinary β2-microglobulin/creatinine ratio (UBCR) as a marker of renal tubulointerstitial damage in the general Japanese population. Methods We examined the association between UBCR values at entry and all-cause and cardiovascular mortality during the follow-up period (median 9.2 years) in 3 427 residents (mean age 62.5 years, 45.1% male, mean eGFR 81.6 ml/min/1.73 m², ≥1+ protein 4.4%) of Takahata Town in Japan. Results Study participants were divided into two groups (low &amp;lt; 300 μg/gCre, high ≥300 μg/gCre) based on UBCR at entry. Kaplan-Meier analysis showed a significantly higher incidence of all-cause and cardiovascular mortality in the high UBCR group (Log-rank P &amp;lt; 0.01). A multivariate Cox proportional hazards analysis adjusted for age, sex, eGFR, urinary protein level, comorbidities, smoking status, and other background factors showed a hazard ratio of 1.47 (95% CI 1.09-2.00, P = 0.01) for all-cause mortality and a hazard ratio of 1.82 (95% CI 1.06-3.12, P = 0.03) for cardiovascular death in the high-UBCR group. The addition of high UBCR to conventional risk factors, including eGFR and urinary protein level, significantly improved the net reclassification improvement (NRI) for all-cause and cardiovascular mortality (P &amp;lt; 0.01). Conclusions UBCR, a marker of tubulointerstitial damage, was identified as a risk factor for all-cause and cardiovascular mortality in the general population independent of eGFR and urinary protein levels.

#2187 Rare disease, novel approach: C3GN and Iptacopan case report

Abstract Background and Aims C3 glomerulonephritis (C3GN) is a rare disease characterised on biopsy by proliferative lesions of predominant C3 deposition on immunofluorescence, particularly deposits within the mesangium and capillary walls. Dysregulation of the alternative complement pathway is thought to be the underlying mechanism [1]. There are no approved treatments for C3G and prognosis is poor, with 50% progression to kidney failure over 10 years and similar rates of transplant loss due to disease recurrence. Iptacopan (a selective Factor B complement inhibitor) is proposed to suppress key enzymes involved in the alternative pathway cascade [2]. It is being studied in clinical trials of C3G [3]. We sought to describe our experience in diagnosing and managing a 25-year-old with C3GN who presents with nephrotic syndrome, hypertension, and a reduction in his estimated glomerular filtration rate (eGFR) with a novel small molecule therapeutic. Method This report charts the clinical course of one male patient over 11 months from presentation with C3GN, to the introduction of immunosuppression and of Iptacopan, and the assessment of his response to the foregoing. The patient consented to the publication of his case. Results A 25-year-old male with a background of autism spectrum disorder was referred to his regional nephrology service due to reduction in his eGFR and proteinuria. His creatinine was 158 µmol/L with an eGFR was 51.8 ml/ml/1.73 m2 (CKD-EPI equation); urinary protein creatinine ratio (uPCR) 500 mg/mmol; urinary albumin creatinine ratio (uACR) 400.2 mg/mmol. Serum album 32g/L. His C3 0.22 (normal range 0.82–1.85 g/L); C4 0.27 (normal 0.15–0.53 g/L). A renal biopsy was performed which demonstrated diffuse MPGN dominant C3 staining; cholesterol crystals; and moderate to severe chronic tubulointerstitial damage. 1 mg/kg oral prednisolone with mycophenolate mofetil (MMF) titrated up to a dose of 1g twice a day was initiated. As he was established on the therapy his eGFR rose back to 57.9 ml/min over approximately 8 weeks from a nadir of 33.8 ml/min. Following initial weaning of his prednisolone dose, his eGFR dropped back down to 29.7 ml/min with a creatinine of 250 µmol/L. With involvement and clinical support from the National Renal Complement Therapeutics Centre an application was made to Novartis for the compassionate use of Iptacopan which was commenced early August 2023 (he would not have been eligible for recruitment into any current clinical trials). His latest eGFR is 47.5 ml/ml/1.73 m2 with a uACR of 9.1 mg/mmol and normal C3 and C5b-9 levels after 5 months of Iptacopan. His prednisolone dose is 10 mg. MMF continues at 2g total dose. Conclusion Iptacopan has so far resulted in the normalisation of serum C3 levels, reduction of uACR and stabilisation of serum creatinine as we have reduced the prednisolone dose.

Effects of Long-lasting Volleyball Training on Tubulointerstitial Damage in Adolescent Female Athletes

In adolescent female athletes, monitoring physical condition using non-invasive methods such as urine could speed the provision of information to athletes and coaches, thereby preventing injuries and promoting improved performance. On this matter, it has been reported that physical stress is cumulatively increased by prolonged training in adolescent female athletes. Given the potential to monitor the cumulative effects of long-term training at the level of renal function, this could provide appropriate feedback to adolescent female athletes regarding their physical condition. Accordingly, the purpose of this study was to clarify the accumulative effects of long-term volleyball training on renal damage, based on urinary liver-type fatty acid-binding protein (L-FABP), in adolescent female athletes. Twenty-one eumenorrhoeic female volleyball players (as baseline values; age: 16.4±0.8 years, height: 161.9±5.8 cm, body mass: 55.6±5.7 kg, BMI: 21.8±1.2 kg/m2, body fat: 24.5±3.0 % [mean±SD]) participated in this study. All athletes carried out volleyball training in the school gym, which consisted of ball handling, specialized drills, and practical game-style exercises, including physical (aerobic/anaerobic) training. The training cycle was six days per week, with approximately 2 to 2.5 hours of volleyball training per day. In order to determine the cumulative effects of tubular injury (urinary L-FABP), urine samples were collected before and after volleyball club activities on three successive days (Days 1, 3, and 5) at 0 (baseline) and 10 months (two consecutive summer seasons), respectively, for the later analysis of urinary L-FABP using chemiluminescent enzyme immunoassay. Student's T-test was performed on the analyzed data of urine samples collected prior to the club activity, using values calculated as the mean of three consecutive days. No significant difference was observed in urinary L-FABP after 10 months of volleyball training (μg/g creatinine; 1.39±1.6 for 0 month, 1.17±0.8 for 10 months, respectively). The results of this study may partially explain the possibility that training adaptation occurred or that a threshold to overtraining was not reached after one year of training. Since physiological and environmental factors such as heat stress are presumed to be intricately involved in long-term training in a non-air-conditioned indoor environment, the biomarkers used in this experiment may be important dependent variables in monitoring overtraining of female indoor athletes. Supported partly by funds from Wesco Scientific Promotion Foundation (2022-71 to N. Y.) in Japan. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A Novel Monoallelic ALG5 Variant Causing Late-Onset ADPKD and Tubulointerstitial Fibrosis

IntroductionMonoallelic variants in the ALG5 gene encoding asparagine-linked glycosylation protein 5 homolog (ALG5) have been recently shown to disrupt polycystin-1 maturation and trafficking via underglycosylation, causing an autosomal dominant polycystic kidney disease-like (ADPKD-like) phenotype and interstitial fibrosis. In this report we present clinical, genetic, histopathologic, protein structure and functional correlates of a new ALG5 variant, p.R79W, that we identified in two distant genetically related Irish families displaying an atypical late-onset ADPKD phenotype combined with tubulointerstitial damage. MethodsWhole exome and targeted sequencing were used for segregation analysis of available relatives. This was followed by immunohistochemistry examinations of kidney biopsies, and targeted (UMOD, MUC1) and untargeted plasma proteome and N-glycomic studies. ResultsWe identified a monoallelic ALG5 variant [GRCh37 (NM_013338.5): g.37569565G>A, c.235C>T; p.R79W] that co-segregates in 23 individuals, of whom 18 were clinically affected. We detected abnormal localization of ALG5 in the Golgi apparatus of renal tubular cells in patients’ kidney specimens. Further, we detected the pathological accumulation of uromodulin, an N-glycosylated GPI-anchored protein, in the endoplasmic reticulum, but not mucin-1, an O- and N-glycosylated protein. Biochemical investigation revealed decreased plasma and urinary uromodulin levels in clinically affected individuals. Proteomic and glycoproteomic profiling revealed the dysregulation of chronic kidney disease-associated proteins. ConclusionALG5 dysfunction adversely affects maturation and trafficking of N-glycosylated and GPI anchored protein uromodulin, leading to structural and functional changes in the kidney. Our findings confirm ALG5 as a cause of late-onset ADPKD and provide additional insight into the molecular mechanisms of ADPKD-ALG5.

A Comparative Analysis of Fractional Excretion of Sodium, Potassium and Magnesium among T2DM Patients with Increased Albuminuria and Normal Albuminuria in a Tertiary Care Hospital- An Observational Study

Background: T2DM often leads to diabetic kidney disease, a condition marked by change in GFR and urinary albumin excretion. The renal handling of key electrolytes like sodium, potassium, and magnesium plays a crucial role in the progression of renal tubulointerstitial damage in diabetic patients. Aim of the study: The aim of this study was to compare the fractional excretion of sodium, potassium and magnesium among T2DM patients with increased albuminuria and normal albuminuria. Methods: This observational study was conducted in Department of Nephrology, Chattogram, Bangladesh from February 2021 to January 2022. Total 125 patients with T2DM were included in this study. Result: Baseline characteristics showed no significant differences across the study groups. Biochemically, eGFR decreased non-significantly from 95.5 to 86.1 ml/min/1.73 m² across groups, while UACR significantly increased from 14.3 to 1056 mg/gm (P&lt;0.001). FBG levels were similar, but 2hPPBG showed a significant decrease from 8.2 to 7.4 mmol/l (P=0.0041). HbA1C levels varied slightly. FENa, FEK, and FEMg showed significant differences across groups, with FENa ranging from 0.59% to 0.56% (P=0.0016), FEK from 9.4% to 6.9% (P=0.0358), and FEMg from 2.87% to 5.58% (P=0.001). Correlations revealed significant negative associations of eGFR with FENa, FEK, and FEMg, and a significant positive correlation of FEMg with UACR. No significant correlations were found between FBG, 2hPPBG, HbA1C, and the electrolytes excretion. Conclusion: Significant variations in the fractional excretion of sodium, potassium, and magnesium were observed. Higher eGFR was associated with lower electrolyte excretion, and a significant positive correlation was found between magnesium excretion and UACR.