Glomerular Membrane Research Articles

Autoantibodies Targeting Proteasome Subunit Alpha Type 1 in Autoimmune Podocytopathies.

The antibody against proteasome subunit alpha type 1 (PSMA1) is a podocyte autoantibody in idiopathic nephrotic syndrome (INS) children identified in our previous study. The aim of this study was to explore the characteristics of INS in children and the mechanism underlying its involvement in the development of INS. The levels of serum anti-PSMA1 autoantibodies in children were detected via protein microarray and compared among different disease groups. The recombinant PSMA1 protein was injected subcutaneously and intraperitoneally into mice to observe glomerular morphology and function. The PSMA1-knockdown and PSMA1-overexpressing cell lines were constructed from mouse podocytes, and their cytoskeleton and function were analyzed. Homozygous zebrafish with psma1 knockout were observed. The levels of serum anti-PSMA1 autoantibodies were higher in INS children and varied with urinary protein. In mice immunized with PSMA1, the presence of serum anti-PSMA1 autoantibody caused albuminuria and damage to the glomerular filtration membrane. Deficiency of PSMA1 impaired the podocyte cytoskeleton and physiological function. Complete deletion of psma1 caused edema, abnormal glomerular morphology and effacement of foot processes in zebrafish. PSMA1 played an important role in the maintenance of podocyte morphology and function.

Effects of long-term dehydration and quick rehydration on the camel kidney: pathological changes and modulation of the expression of solute carrier proteins and aquaporins

BackgroundRecurrent dehydration causes chronic kidney disease in humans and animal models. The dromedary camel kidney has remarkable capacity to preserve water and solute during long-term dehydration. In this study, we investigated the effects of dehydration and subsequent rehydration in the camel's kidney histology/ultrastructure and changes in aquaporin/solute carrier proteins along with gene expression.ResultsIn light microscopy, dehydration induced few degenerative and necrotic changes in cells of the cortical tubules with unapparent or little effect on medullary cells. The ultrastructural changes encountered in the cortex were infrequent during dehydration and included nuclear chromatin condensation, cytoplasmic vacuolization, mitochondrial swelling, endoplasmic reticulum/ lysosomal degeneration and sometimes cell death. Some mRNA gene expressions involved in cell stability were upregulated by dehydration. Lesions in endothelial capillaries, glomerular membranes and podocyte tertiary processes in dehydrated camels indicated disruption of glomerular filtration barrier which were mostly corrected by rehydration. The changes in proximal tubules brush borders after dehydration, were accompanied by down regulation of ATP1A1 mRNA involved in Na + /K + pump that were corrected by rehydration. The increased serum Na, osmolality and vasopressin were paralleled by modulation in expression level for corresponding SLC genes with net Na retention in cortex which were corrected by rehydration. Medullary collecting ducts and interstitial connective tissue were mostly unaffected during dehydration. CKD, a chronic nephropathy induced by recurrent dehydration in human and animal models and characterized by interstitial fibrosis and glomerular sclerosis, were not observed in the dehydrated/rehydrated camel kidneys. The initiating factors, endogenous fructose, AVP/AVPR2 and uric acid levels were not much affected. TGF-β1 protein and TGF-β1gene expression showed no changes by dehydration in cortex/medulla to mediate fibrosis. KCNN4 gene expression level was hardly detected in the dehydrated camel's kidney; to encode for Ca + + -gated KCa3.1 channel for Ca + + influx to instigate TGF-β1. Modulation of AQP 1, 2, 3, 4, 9 and SLC protein and/or mRNAs expression levels during dehydration/rehydration was reported.ConclusionsLong-term dehydration induces reversible or irreversible ultrastructural changes in kidney cortex with minor effects in medulla. Modulation of AQP channels, SLC and their mRNAs expression levels during dehydration/rehydration have a role in water conservation. Cortex and medulla respond differently to dehydration/rehydration.

Ultrasmall Polyphenol-NAD+ Nanoparticle-Mediated Renal Delivery for Mitochondrial Repair and Anti-Inflammatory Treatment of AKI-to-CKD Progression.

As a central metabolic molecule, nicotinamide adenine dinucleotide (NAD+) can potentially treat acute kidney injury (AKI) and chronic kidney disease (CKD); however, its bioavailability is poor due to short half-life, instability, the deficiency of targeting, and difficulties in transmembrane transport. Here a physiologically adaptive gallic acid-NAD+ nanoparticle is designed, which has ultrasmall size and pH-responsiveness, passes through the glomerular filtration membrane to reach injured renal tubules, and efficiently delivers NAD+ into the kidneys. With an effective accumulation in the kidneys, it restores renal function, immune microenvironment homeostasis, and mitochondrial homeostasis of AKI mice via the NAD+-Sirtuin-1 axis, and exerts strong antifibrotic effects on the AKI-to-CKD transition by inhibiting TGF-β signaling. It also exhibits excellent stability, biodegradable, and biocompatible properties, ensuring its long-term safety, practicality, and clinical translational feasibility. The present study shows a potential modality of mitochondrial repair and immunomodulation through nanoagents for the efficient and safe treatment of AKI and CKD.

#3084 Familial nephropathy associated with a combined mutations of Alport and Nail Patella syndrome genes in the same family

Abstract Introduction Alport syndrome is a genetic condition stemming from mutation in Type IV collagen and is characterized by kidney disease and frequently hearing loss and ocular abnormalities. Renal involvement is from an abnormality of the glomerular basement membrane with hematuria and proteinuria progressing eventually to renal failure. In the vast majority, the inheritance is X- linked affecting the alpha 5 chain of type IV collagen while in about 15 percent of the patients the inheritance is autosomal recessive or dominant with mutations affecting alpha 3 or 4 chains of type IV collagen. Sensorineural deafness is common and ocular abnormalities may include lenticonus, corneal opacities, fleck retinopathy and temporal retinal thinning. Nail Patella syndrome (NPS) is a rare genetic condition from mutation in the LMX1B gene on chromosome 9 with an autosomal dominant inheritance. Glomerular disease is from characteristic glomerular basement membrane changes and is associated with nail, pelvic girdle and limb abnormalities. A forme fruste with glomerular lesions but lacking extrarenal features is recognized but uncommon. We present a family with mutations in both COL4A5 and LMX1B presenting with hematuria and proteinuria Case Presentation A 23 year old female was evaluated for hematuria and proteinuria. Her history was notable for kidney biopsy at the age thirteen showing focal and segmental glomerulosclerosis (FSGS). She was treated with tacrolimus for four years from age thirteen through seventeen. Patient was reportedly diagnosed with Nail Patella Syndrome after genetic testing. Her family history was notable for hematuria in her brother and hematuria and proteinuria in her mother. On physical examination she was noted to have no nail or skeletal abnormalities associated with Nail Patella Syndrome. Her labs were notable for a serum creatinine of 0.6 mg/dl and proteinuria of 155 mg/g creatinine of proteinuria. Urine microscopy revealed dysmorphic hematuria. Radiological imaging did not show skeletal abnormalities observed in Nail Patella Syndrome but genetic testing identified a pathogenic variant in COL4A5 c.919G>A (p.Gly307Ser) in addition to a variant of uncertain significance in LMX1B c.349G>A (p.Gly117Ser). Her brother aged 20 had a creatinine of 0.87 mg/dl with dysmorphic hematuria and no proteinuria. Genetic testing showed the same pathogenic variant in COL4A5 as in his sibling. His mother aged 55 was subsequently evaluated and had a creatinine 0.73 mg/dl with dysmorphic hematuria and 152 mg/g of proteinuria. Genetic testing was with the same variant in COL4A5 noted in her two children. Renal biopsy was extensive thinning and segmental lamellation of the glomerular basement membrane with eight percent FSGS. The typical “moth-eaten” appearance of the glomerular basement membrane characteristic of NPS was not evident. Segmental staining was observed with alpha 5 unit of Type IV collagen. Audiology and retinal optical coherence optometry studies are pending. Discussion Alport syndrome and Nail Patella Syndrome are rare genetic disorders that cause variable degrees of renal insufficiency from glomerular base membrane defects and are associated with characteristic extra renal manifestations. This is the first report of an inherited nephritis with combined mutations in COL4A5 and LMX1B. The clinical features and renal biopsy are compatible with Alport Syndrome and the significance of the mutation in LMX1B is uncertain. Conclusion This is the first case report of a combined mutation in COL4A5 and LMX1B gene presenting with hematuria and minimal proteinuria with preserved kidney function.

#993 The molecular effects of SGLT2i (Empagliflozin) on α-Klotho and Nephrin/Podocin proteins in type II diabetic mice model

Abstract Background and Aims Type 2 diabetes mellitus (T2DM), especially hyperglycemia, is associated with increased glucose cell toxicity and oxidative stress that can lead to irreversible damage in the kidney such as diabetic nephropathy (DN). DN is one of the most common microvascular complications of diabetes and is the leading cause of end-stage renal disease (ESRD) and replacement therapy. Several works in the setting of early experimental diabetic nephropathy using the recent anti-diabetic drugs such as sodium-glucose transporter type 2 inhibitors in the prevention, development or amelioration of renal injury. The exact mechanisms, by which these drugs ameliorate glomerular injury from hyperglycemia, had not been clarified well. Klotho and Podocin-Nephrin proteins are an important proteins involved in the tubule-glomerular injury. The Klotho is a circulating anti-ageing hormone with anti-oxidative and anti-inflammatory properties with vascular protective effects in animal studies. Podocin & Nephrin are important component of the glomerular foot-process membrane, the slit-diaphragm. Recently, several experimental reports showed decreased α-Klotho, Nephrin and Podocin expression in different models of diabetic nephropathy. Method We used BTBR mouse strain with the ob/ob leptin-deficiency mutation, which develops T2DM with hyperglycemia and DN; C57/BL mice were the control (CON). EMPA was administrated to T2DM mice (T2DM+EMPA) via drinking water for 12 weeks. Blood parameters were measured repeatedly, and at sacrifice, mice kidneys were harvested for histological and biochemical analyses. We evaluated renal glomerular structure of Nephrin, Podocin and α-Klotho proteins expression. Results EMPA treatment reduced T2DM blood glucose vs C57 group (P < 0:01), and increase urine glucose in EMPA+DM group (P < 0:001) EMPA vs. C57BL/6 and DM). Histological analyses in kidney sections, revealed decreased α-Klotho expression in glomeruli of DM mice vs Control mice (15.95 ± 0.64 vs 36 ± 2.42, (P < 0:01), and restored back in DM+ EMPA mice vs control mice (27.64 ± 0.94 vs 15.95 ± 0.64, P < 0:01). Podocin expression in glomeruli: control mice 31.3 ± 3.7 VS DM mice 21.26 ± 1.22 and DM + EMPA mice 28.22 ± 0.50 VS DM mice 21.26 ± 1.22 Conclusion Hyperglycemia (DM type II) reduces Podocin-Nephrin and α-Klotho proteins expression in the glomeruli kidney and upregulated by EMPA treatment. SGLT2i (EMPA) treatment in DM patients can significantly reduce progression of DN and onset of ESRD probably through its effect on α-Klotho/Podocin-Nephrin proteins.

#2672 Cryoglobulin-Induced membranoproliferative glomerulonephritis in a HEV-infected kidney transplant recipient: outcomes post ribavirin failure

Abstract Background and Aims Hepatitis E is a zoonosis caused by hepatitis E virus (HEV), which was first discovered 40 years ago. It is the most prevalent hepatitis virus worldwide. Most hepatitis E cases are self-limiting acute hepatitis, but the virus has been recognized to cause chronic hepatitis. Following the first case report of chronic hepatitis E (CHE) in a transplant recipient, CHE has recently been identified as associated with chronic liver damage induced in immunocompromised patients such as transplant recipients. CHE can induce extra-hepatic manifestations, such as immune-mediated thrombocytopenia, neurological symptoms, and kidney injuries. Few cases of glomerulonephritis (GN) and cryoglobulinemia in transplant patients have been related with CHE, with a good progression thanks to viral control with ribavirin introduction. There have been no reported cases in the literature of good progress in renal function in renal transplant patients despite failure of treatment with Ribavirin. Method We report here what is to our knowledge, the first documented case of HEV-induced de novo cryoglobulinemic membranoproliferative glomerulonephritis in a renal transplant patient with a ten-year history of CHE infection unsuccessfully treated with ribavirin. Results A 69-year-old man underwent a kidney transplant for diabetes type 1. 7 years after transplantation, he was diagnosed with a chronic genotype 3.1H-HEV infection. He was treated by Ribavirin, but it did not allow to eradicate HEV but a biochemical response. At 18 years post transplant, he presented with asthenia, abdominal pains and increased liver enzyme levels: liver tests were disrupted with cytolysis and cholestasis. He presented also a nephritic syndrome with high blood pressure, oedemas, increased serum creatinine level, proteinuria with hypoalbuminemia and de novo microscopic hematuria. Biological analysis revealed presence of type 2 cryoglobulinemia with monoclonal IgM Kappa (2285 mg/L), and polyclonal immunoglobulins association. Rheumatoid factor was increased (573 UI/ml) and C4 level was reduced (0.04 g/L). The concentration of HEV RNA in the serum was 750 000 UI/mL. Viral serologies were performed for HBV, HCV, HAV, HIV, EBV, CMV. Hematologic diseases were ruled out by analyzing a bone marrow biopsy specimen. Histologic analysis of a kidney biopsy specimen revealed diffuse endocapillary proliferation, diffuse mesangial proliferation and focal glomerular basal membrane duplication. One arteriolar section showed a focal lesion of vasculitis (Fig. 1). There was no argument for allograft rejection. Immunofluorescence microscopy revealed mesangial and capillary wall deposits of IgM, IgG, C3 and C1q, polytypic for k and l light chains. We suspected cryoglobulinemic membranoproliferative glomerulonephritis induced by VHE. The initial treatment plan involved 10 sessions of plasmapheresis and steroid pulses (500 mg/d for 3 days), alongside a course of rituximab (1 g/week for 4 weeks). However, the patient experienced intolerance to rituximab, prompting a switch to Obinutuzumab. Subsequently, the anti-HEV therapy was modified, and the patient was placed on a course of Sofosbuvir. Consequently, three months after treatment kidney function kidney improved with return to baseline and cryoglobulinemia became undetectable. However, proteinuria remained impaired and VHE RNA was still present. Conclusion Cryoglobulinemia is rarely associated with glomerular disease in HEV infection, and cases currently reported in the literature showed a favorable outcome with ribavirin. This case is the first to display a chronic HEV infection with cryoglobulin-induced glomerulonephritis with global improvement despite unsuccessful treatment with ribavirin. Although the difficulty of managing immunity in the treatment of cryoglobulinemia by immunodepleting treatment, with the risk of increased viral replication in the absence of an effective antiviral, it seems interesting to offer a first-line treatment of cryoglobulinemia that appears to improve renal function despite continued viral replication. These results need to be confirmed in further studies.

A conjoint analysis of renal structure and omics characteristics reveal new insight to yak high-altitude hypoxia adaptation

BackgroundYaks have unique adaptive mechanisms to the hypoxic environment, in which the kidney plays an important role. The aim of this study was to explore the histological changes of yak kidney at different altitudes and the metabolites and genes associated with adaptation to the hypoxic environment. MethodsWe analyzed the tissue structure and transcriptomic metabolomic data of yak kidney tissue at two altitudes, 2600 and 4400 m. We compared and identified the morphological adaptations of the kidney and the metabolites and genes associated with hypoxia adaptation in yaks. Changes in renal morphological adaptations, differential metabolites and genes were compared and identified, combining the two in a joint analysis. ResultsHigh-altitude yak kidneys showed significant adaptive changes: increased mitochondria, increased glomerular thylakoid area, and decreased localized ribosomes. Transcriptomics and metabolomics identified 69 DAMs (Differential metabolites) and 594 DEGs (differential genes). Functional enrichment analysis showed that the DAMs were associated with protein digestion and absorption, ABC transporter, and MTOR signaling pathway; the DEGs were significantly enriched in Cholesterol metabolism and P53 signaling pathway. The joint analysis indicated that metabolites such as lysine and arginine, as well as key genes such as ABCB5 and COL1A2, were particularly affected under hypoxic conditions, whereas changes in mitochondria in the tissue structure may be related to the expression of MFN1 and OPA1, and changes in glomerular thylakoid membranes are related to VEGFA and TGFB3. ConclusionThe kidney regulates metabolites and gene expression related to hormone synthesis, protein metabolism, and angiogenesis by adjusting the mitochondrial and glomerular thylakoid membrane structure to support the survival of yaks in high-altitude environments.

Hepatic and renal effects of oral stingless bee honey in a streptozotocin-induced diabetic rat model.

Diabetes is known damage the liver and kidney, leading to hepatic dysfunction and kidney failure. Honey is believed to help in lowering the blood glucose levels of diabetic patients and reducing diabetic complications. However, the effect of stingless bee honey (SBH) administration in relieving liver and kidney damage in diabetes has not been well-studied. To investigate the effect of SBH administration on the kidney and liver of streptozotocin-induced (STZ; 55 mg/kg) diabetic Sprague Dawley rats. The rats were grouped as follows (n = 6 per group): non-diabetic (ND), untreated diabetic (UNT), metformin-treated (MET), and SBH+metformin-treated (SBME) groups. After successful diabetic induction, ND and UNT rats were given normal saline, whereas the treatment groups received SBH (2.0 g/kg and/or metformin (250 mg/kg) for 12 d. Serum biochemical parameters and histological changes using hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) staining were evaluated. On H&E and PAS staining, the ND group showed normal architecture and cellularity of Bowman's capsule and tubules, whereas the UNT and MET groups had an increased glomerular cellularity and thickened basement membrane. The SBH-treated group showed a decrease in hydropic changes and mild cellularity of the glomerulus vs the ND group based on H&E staining, but the two were similar on PAS staining. Likewise, the SBME-treated group had an increase in cellularity of the glomerulus on H&E staining, but it was comparable to the SBH and ND groups on PAS staining. UNT diabetic rats had tubular hydropic tubules, which were smaller than other groups. Reduced fatty vacuole formation and dilated blood sinusoids in liver tissue were seen in the SBH group. Conversely, the UNT group had high glucose levels, which subsequently increased MDA levels, ultimately leading to liver damage. SBH treatment reduced this damage, as evidenced by having the lowest fasting glucose, serum alanine transaminase, aspartate transaminase, and alkaline phosphatase levels compared to other groups, although the levels of liver enzymes were not statistically significant. The cellularity of the Bowman's capsule, as well as histological alteration of kidney tubules, glomerular membranes, and liver tissues in diabetic rats after oral SBH resembled those of ND rats. Therefore, SBH exhibited a protective hepatorenal effect in a diabetic rat model.

Effect of intermittent fasting on adriamycin-induced nephropathy: Possible underlying mechanisms

PurposeIntermittent fasting (IF) has been shown to induce a well-organized adaptive defense against stress inside the cells, which increases the production of anti-oxidant defenses, repair of DNA, biogenesis of mitochondria, and genes that combat inflammation. So, the goal of the current investigation was to identify the effects of IF on rats with adriamycin (ADR)-induced nephropathy and any potential underlying mechanisms. MethodsFour groups of 40 mature Sprague-Dawley male rats were allocated as follow; control, fasting, ADR, and ADR plus fasting. After 8 weeks of ADR administration urine, blood samples and kidneys were taken for assessment of serum creatinine (Cr), BUN, urinary proteins, indicators of oxidative damage (malondialdehyde (MDA), reduced glutathione (GSH) and Catalase (CAT) levels), histopathological examinations, immunohistochemical examinations for caspase-3, Sirt1, aquaporin2 (AQP2) and real time PCR for antioxidant genes; Nrf2, HO-1 in kidney tissues. ResultsIF significantly improved serum creatinine, BUN and urinary protein excretion, oxidative stress (low MDA with high CAT and GSH), in addition to morphological damage to the renal tubules and glomeruli as well as caspase-3 production during apoptosis. Moreover, IF stimulates significantly the expression of Sirt1 and Nrf2/HO-1 and AQP2. ConclusionAQP2, Sirt1, Nrf2/HO-1 signaling may be upregulated and activated by IF, which alleviates ADR nephropathy. Enhancing endogenous antioxidants, reducing apoptosis and tubulointerstitial damage, and maintaining the glomerular membrane's integrity are other goals.

Rein et diabète ne font pas bon ménage

AbstractThis clinical case shows bad household between diabetes and kidney, and when arterial hypertension gets in the way! A woman with diabetes for a long time and treated with metformin presents metabolic syndrome with type 2 diabetes, arterial hypertension difficultly controlled by antihypertensive drugs, dyslipidaemia and chronic kidney failure (CKF) which worsens regularly. Gradually, glucose in excess in blood plasma glycosylates renal glomerular membranes meaning to diabetes nephropathy, which can be revealed by a nephrotic syndrome, no pure as in the present case with an arterial hypertension resistant to therapy. Acute kidney failure crisis is in the frame of CKF, which worsens with decline of glomerular filtration rate (GFR), large increase in albuminuria and heavy antihypertensive therapy. Vicious circle sets in because CKF increases arterial tension meaning to enhance antihypertensive therapy itself toxic for the kidney. To break this vicious circle, on the one hand we have to better control diabetes and on the other hand, to control hypertension by choosing drugs protective for the kidney. Every new decrease in GFR or increase in albuminuria makes you fear of a new acute renal failure crisis that you have to take care quickly. Diabetes is the main cause of renal transplantation.

Bioinspired Gradient Covalent Organic Framework Membranes for Ultrafast and Asymmetric Solvent Transport.

Gradients play a pivotal role in membrane technologies, e.g., osmotic energy conversion, desalination, biomimetic actuation, selective separation, and more. In these applications, the compositional gradients are of great relevance for successful function implementation, ranging from solvent separation to smart devices; However, the construction of functional gradient in membranes is still challenging both in scale and directions. Inspired by the specific function-related, graded porous structures in glomerular filtration membranes, a general approach for constructing gradient covalent organic framework membranes (GCOMx) applying poly (ionic liquid)s (PILs)as template is reported here. With graded distribution of highly porous covalent organic framework (COF) crystals along the membrane, GCOMx exhibts an unprecedented asymmetric solvent transport when applying different membrane sides as the solvent feed surface during filtration, leading to a much-enhanced flux (10-18 times) of the "large-to-small" pore flow comparing to the reverse direction, verified by hydromechanical theoretical calculations. Upon systematic experiments, GCOMx achieves superior permeance in nonpolar (hexane≈260.45 LMH bar-1) and polar (methanol≈175.93 LMH bar-1) solvents, together with narrow molecular weight cut-off (MWCO, 472g mol-1) and molecular weight retention onset (MWRO, <182g mol-1). Interestingly, GCOMx shows significant filtration performance in simulated kidney dialysis, revealing great potential of GCOMx in bionic applications.

Goodpasture Syndrome with Neurological Condition Associated with anti-MBG Ab, Negative ANCA: Case Report

Goodpasture syndrome is a rare immunologically based clinical entity that is characterized by rapidly progressive glomerulonephritis, diffuse pulmonary hemorrhage, and the presence of circulating autoantibodies against the glomerular basement membrane (GBM). Concomitant central nervous system (CNS) manifestations are an unusual presentation of GSP in the absence of ANCA. We present a case of atypical course of the disease in a 48-year-old female patient who started with the presence of hemoptoic sputums and manifestations of uremic syndrome in the presence of high titres of glomerular basement anti membrane antibodies (Ac-anti-MBG) and negative ANCA, with a report of diffuse active extracapillary proliferative glomerulonephritis biopsy, of the pauciimmune type. After immunosuppressive treatment and plasmapheresis, the patient presented decreased anti-MBG Ab titres, as well as improvement of symptoms, however without recovery of renal function on hemodialysis, after 2 months he presents clonic-tonic seizures crisis, we conclude that PGS with neurological involvement is extremely rare, especially with negative ANCAs.

EGFRcystatinC/eGFRcreatinine ratio < 0.6 in patients with SARS-CoV-2 pneumonia: a prospective cohort study

BackgroundShrunken Pore Syndrome (SPS), defined as a reduced ratio between two estimated filtration rates (based on cystatin C and creatinine) is an increasingly recognized risk factor for long-term mortality. Although some patients with other conditions might be erroneously identified as SPS. Our aim was to bring the focus on possible pathophysiologic mechanisms influencing the ratio in the setting of SARS-CoV-2 pneumonia and acute kidney injury.MethodsA single-centered prospective cohort study was conducted to investigate biomarkers in symptomatic COVID-19 pneumonia patients admitted to a hospital in Latvia. Nineteen biomarkers were measured in blood and three in urine samples. Associations were sought between these biomarkers, chronic diseases and the estimated GFRcystatinC/eGFRcreatinine ratio < 0.6, mortality rates, and acute kidney injury development. Data analysis was performed using SPSS Statistics, with significance set at p < 0.05.ResultsWe included 59 patients (average age 65.5 years, 45.8% female) admitted with COVID-19. Acute kidney injury occurred in 27.1%, and 25.4% died. Ratio < 0.6 was seen in 38.6%, associated with female sex, diabetes, hypothyroidism, and higher age. Ratio < 0.6 group had mortality notably higher − 40.9% vs. 16.2% and more cases of acute kidney injury (40.9% vs. 18.9%). Cystatin C showed strong associations with the ratio < 0.6 compared to creatinine. Urea levels and urea/creatinine ratio were higher in the ratio < 0.6 group. After excluding acute kidney injury patients, ratio < 0.6 remained associated with higher cystatin C and urea levels. Other biomarkers linked to a kidney injury as NGAL, and proteinuria did not differ.ConclusionWe prove that reduced ratio is common in hospitalized patients with SARS-CoV-2 pneumonia and is associated with increased mortality during hospitalization. Factors that influence this ratio are complex and, in addition to the possible shrinkage of pores, other conditions such as thickening of glomerular basal membrane, comorbidities, prerenal kidney failure and others may play an important role and should be addressed when diagnosing SPS. We highlight the need for additional diagnostic criteria for SPS and larger studies to better understand its implications in acute COVID-19 settings.

Study of association between antibodies to non-HLA kidney self-antigens and progression to chronic immune injury after kidney transplantation

BackgroundImmune response to several kidney self-antigens (KSAg) such as Collagen IV (Col-IV), Perlecan (PL), and Fibronectin (FN) have been associated with antibody-mediated damage and poor allograft survival. Thus, the aim of this study was to determine if humoral immune responses to KSAg correlates with progression of chronic immune injury (CII) changes at 1 year or 2 years. MethodsKidney transplant recipients who underwent 1- or 2-year biopsies, with chronic interstitial inflammation (ci > 1) and/or glomerular membrane double contouring (cg > 0) were analyzed with matched controls. Sera were analyzed retrospectively for antibodies against KSAg using ELISA. The presence of antibodies to KSAg were compared at 0, 4, 12, and 24 months using logistic regression. ResultsWe identified a cohort of 214 kidney transplant recipients. Of these, we identified 33 cases and matched 66 controls. Logistical regression showed an odds ratio of 1 with the confidence interval crossing 1 for the presence of response to KSAg at all the time points. ConclusionsHumoral immune responses to either KSAg alone or in combination with donor-specific anti-HLA antibodies are not associated with progression to CII at 1 and 2 years after kidney transplantation.

#3271 EXPRESSION OF THE COLLAGEN IV α345 MOLECULE ALONG THE RENAL TUBULE IN HEALTH AND DISEASE

Abstract Background and Aims Patients suffering from Alport Syndrome (AS) have a high life time risk of kidney failure and hearing loss. The underlying molecular cause is a germline mutation in one of the COL4A3/4/5 genes, whose gene products collectively form an important component of the glomerular basement membrane and the inner ear. Recent genetic studies have shown that the AS is much more prevalent than clinically recognized, suggesting that atypical clinical cases are frequent. Thus, patients with AS may phenocopy other kidney diseases. To date, pathomechanistic studies of the AS have focused exclusively on the glomerular membrane, yet equally strong expression of collagen IV can be found along the distal renal tubule. Structural disintegration of the distal tubular membrane may induce inflammation and fibrosis, thus progression of kidney disease. We hypothesize that genetic loss of the tubular collagen IV molecule contributes to kidney failure and may drive atypical phenotypes. Method Immunohistochemistry (IHC) and in situ hybridization (ISH, RNAscope) for COL IV α5, where IHC was performed on healthy human tissues as well as biopsies from patients with AS. Tubular marker staining for localization of COL IV α5 expression as well as spatial changes on consecutive sections. Human urinary primary tubular cells (huPTC) from healthy probands and patients with AS were generated and cultivated in cell culture, with analysis of COL IV mRNA by qPCR and detection of specifically expressed proteins by immunoblotting. Results COL IV α5 was detected within the tubular basement membrane (TBM) of the distal segments of renal tubules by IHC, including the thick ascending limb (TAL) of Henle (Tamm-Horsfall Protein), the distal convoluted tubule (11ß-Hydroxysteroid-Dehydrogenase) and the collecting duct (aquaporin 2). Spacial vicinity of these areas showed a predominance of interstitial fibrosis and inflammation in patient samples with AS, but not control samples with primary proteinuric diseases. Collagen IV protein is lost along the TBM of patients with AS, even in the hemizygous male and heterozygous female carriers of the hypomorphic but frequent COL4A5 mutation G624D. By ISH, COL4A5 expression was mainly observed in the glomerulus (most likely podocytes) and broadly in tubular epithelial cells, with only few tubulointerstitial cells showing mRNA expression. Likewise, the huPTC showed COL IV expression in qPCR, as well as COL IV α5 protein in immunoblotting. Conclusion Our studies show that the COL IV molecule is situated within the TBM of the complete distal tubule, starting from the TAL throughout the distant collecting duct. Although the epithelial cells have no detectable protein, in situ hybridization and primary cell cultures clearly suggest that tubular cells are a major source of the COL IV α345 molecule within the TBM. Renal biopsies of AS patients with diagnostic genetic COL IV variants indicate that tubulointerstitial fibrosis and inflammation starts in the vicinity of the distal tubule. Therefore, we postulate that the pathogenesis of AS may in part stem from the (distal) tubular apparatus, which is already known from other diseases such as ADTKD and nephronophthisis.

#3345 EFFECTS OF CONDITIONED MEDIUMS COLLECTED FROM 2D OR 3D CULTURED MSCS ON KIDNEY FUNCTIONS OF RATS WITH AUTOIMMUNE DIABETES INDUCED WITH STREPTOZOCIN

Abstract Background and Aims The main mechanism of therapeutic action of mesenchymal stem cells (MSCs) could be resulted from their secretome content rather than their direct differentiation into damaged cells [1, 2]. Preconditioning of MSCs with different strategies like culturing in 3 dimensional (3D) culture scaffolds could improve their therapeutic potential [1]. Based on our previous study [1] in which the concentrations of total protein and specifically VEGF and IL-4 in conditioned mediums (CMs) collected from MSCs cultured in 3D culture conditions were increased compared to one of 2D, the aim of this study is comparative analysis of effects of CMs obtained from MSCs incubated under 2D and 3D culture conditions on kidney functions of rats with autoimmune type I diabetes (aT1D) induced with streptozocin (STZ). Method Isolation and characterization of the umbilical cord MSCs and the following analysis of concentrations of total protein and paracrine factors in the 2D-CMs and 3D-CMs were performed as it was mentioned [1]. Sprague-Dawley rats were treated with 20 mg/kg STZ for 5 consecutive days to induce T1D and 12 doses of CMs were intraperitoneally introduced for 4 weeks in accordance with the timeline defined in Figure 1. Therapeutic effects of CMs were comparatively investigated by biochemical, physical, histopathological and immunohistochemical analysis. Results At the end of the 2nd week, urinary albumin/creatinine (u-Alb/Cr) ratio and creatinine removal rate (Crr) of diabetes were significantly aggravated compared to control group (p = 0,0001 and p = 0,13 respectively). At the end of the 7th week, u-Alb/Cr ratios of both treatment groups were significantly improved compared to one of diabetes group (p = 0,029 vs p = 0,002). There was no statistical difference among all groups for Crr values. In the post treatment period u-Alb/Cr ratio was exacerbated (p = 0,014) while Crr value was not changed compared to pre-treatment period (p = 0,713). There was no statistical change between the pre- and post-treatment values of u-Alb/Cr ratio and Crr for both treatment groups. Renal mass index of control group was lower than the ones of experimental groups, while weight percent change from pre- to post-treatment period of control group was statistically higher than the ones of experimental groups (p = 0,0001). However, there was no statistical difference for both parameters among the experimental groups (Figure 2). Histopathological evaluations showed that cortical tubular damage (CTD) was significantly ameliorated in only D+3D-CM group compared to diabetes group (p = 0,012), while there was no statistical change in glomerular fibrosis in both treatment groups (Figure 3.1 and 3.2 respectively). Immunohistochemical analysis indicated that nephrin expression was insignificantly increased in both treatment groups compared to diabetes group (Figure 3.3). Preliminary evaluation of thicknesses of glomerular basal membrane and pedicel with transmission electron microscopy (TEM) showed no clear difference among all the groups (Figure 4). Conclusion CM obtained from MSCs in 3D culture conditions could partially ameliorate kidney functions of aT1D by improving CTD and expression of nephrin which is crucial for the integrity of glomerular filtration barrier.

Endoplasmic reticulum stress in diabetic kidney disease: adaptation and apoptosis after three UPR pathways.

Diabetes kidney disease (DKD) is one of the common chronic microvascular complications of diabetes, which has become the most important cause of modern chronic kidney disease beyond chronic glomerulonephritis. The endoplasmic reticulum is one of the largest organelles, and endoplasmic reticulum stress (ERS) is the basic mechanism of metabolic disorder in all organs and tissues. Under the stimulation of stress-induced factors, the endoplasmic reticulum, as a trophic receptor, regulates adaptive and apoptotic ERS through molecular chaperones and three unfolded protein reaction (UPR) pathways, thereby regulating diabetic renal damage. Therefore, three pathway factors have different expressions in different sections of renal tissues. This study deeply discussed the specific reagents, animals, cells, and clinical models related to ERS in DKD, and reviewed ERS-related three pathways on DKD with glomerular filtration membrane, renal tubular reabsorption, and other pathological lesions of different renal tissues, as well as the molecular biological mechanisms related to the balance of adaption and apoptosis by searching and sorting out MeSH subject words from PubMed database.

Relaxin mechanistic effects on renal hemodynamics and natriuresis: a mathematical modeling approach

Relaxin (RLX) is a hormone that stimulates renal vasodilation during early pregnancy. Recombinant RLX may have potential as a treatment for heart failure and chronic kidney disease, but its application has been limited in part due to uncertainties about its mechanism of action, and particularly its effect on glomerular capillary hydrostatic pressure (P gc ) and fluid status. The objective of this study was to couple mathematical modeling with experimental observations of the renal hemodynamic and natriuretic response to RLX, in order to quantitatively describe the mechanistic effects of relaxin on the kidney, and to predict its effect on clinically difficult-to-measure variables such as P gc . Utilizing a previously developed mathematical model of kidney function and hemodynamics, we began by hypothesizing a minimum set of RLX mechanisms (afferent/efferent vasodilation), fitting the available hemodynamic/natriuretic response in two previously published rat studies (GFR, renal plasma flow (RPF), mean arterial pressure (MAP), sodium and water excretion), and adding additional RLX mechanisms to the model only when the minimal set could not explain available data. We found that changes in renal vascular resistances alone were sufficient to reproduce observed changes in RPF, but insufficient to explain other data features. Experimental studies reported much larger increases in sodium excretion relative to water excretion with RLX, and this effect could only be reproduced if an effect of RLX on the osmotic setpoint for vasopressin release was included in the model – a mechanism that has previously been reported in ovariectomized rats treated with RLX. A small effect of RLX on heart rate was necessary to produce observed changes in MAP.In addition, the single experimental study in which P gc has been measured with RLX reported a rise in GFR but fall in P gc , and this difference could not be explained mathematically by relative afferent/efferent dilation or by downstream shifting of the filtration equilibrium with increased RPF; it could only be reproduced mathematically if RLX was assumed to large positive effect on glomerular membrane permeability. However, the magnitude of this effect is difficult to justify physiologically. Thus, while the model can be forced to fit this limited data, further study is needed to understand whether and how RLX might have such large permeability effects.The fitted model was then able to make predictions consistent with observed renal responses in human subjects, and these effects were better predicted when the RLX effect on permeability was excluded, further suggesting that this effect may not be real. In these simulations, RLX had no net effect on P gc . In conclusion, while some uncertainty remains, this analysis suggests that RLX acts primarily by dilating the afferent and efferent arterioles and shifting the osmotic setpoint for vasopressin release. AstraZeneca and Eli Lilly This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Enzymuria-Early Predictors of Acute Kidney Injury in Animals

Enzymuria is recently being used as valuable tool for the diagnosis of acute kidney injury (AKI), and urinalysis in clinical cases. The origin of enzymes from different parts of the kidney has diagnostic importance. Enzymes of kidney origin, namely those from brush border of proximal tubuli were recognized for their clinical significance inanimals. Now a days, enzymes are more specifically used as tubular markers which determine the location and severity of kidney damage. These enzymes are glutathione S-transferase (GST), N-acetyl-β-D-glucosaminidase (NAG), β-galactosidase (β-GAL), γ-glutamyltranspeptidase and alkaline phosphatase are used as early diagnostic markers of kidney injury. Normally, enzymes originates from serum (as glomerular filtrate), renal tubular cells, and the urogenital tract (epithelial cells, glandular secretion, and semen). The contribution of serum enzymes is negligible for most urinary enzymes because they are relatively larger (&gt; 80 kDa), due to which those marker enzymes do not sieve through the glomerular membrane and appear in the urine. Urinary enzymes have also been used to determine the presence and location of renal tubular injury. Some bacterial or viral infections can damage kidney tubules, which result in the leakage of some enzymes from the tubular epithelium. Various nephrotoxic drugs used in clinical therapeutics, along with some contrast media may lead to acute kidney injury. Enzymes of kidney origin may be released due to damage to the brush border epithelium. Especially, NAG- a lysosomal enzyme in renal tubular epithelium released into urine in response to tubular damage. These enzymes could be increased or identified in urine of urinary tract infected animals.

Effect and mechanism of Yupingfeng Powder on preventing recurrent respiratory tract infection in children with refractory nephrotic syndrome

Primary nephrotic syndrome in children is a group of clinical syndromes caused by the significant increase in the permeability of glomerular filtration membrane to plasma albumin and the loss of a large amount of albumin from urine due to various reasons. It is sensitive to hormones but easy to relapse, and may be dependent on hormones or resistant to drugs after repeated attacks, thus affecting the prognosis. Clinically, it is summarized as refractory nephrotic syndrome in children. Respiratory tract infection is one of the main factors causing the recurrence of refractory nephrotic syndrome in children. Yupingfeng Powder is the prescription of fuzheng Gubenjing, simple and effective, and it is widely used in clinic. Modern research confirmed that Yupingfeng can promote immunoglobulin IgA, IgG, IgE and monocyte macrophages, improve the immune function of the body, in recent years YuPingFeng alone or combined western medicine treatment of children repeated respiratory tract infection shows a unique curative effect and advantages, thus reducing the recurrence frequency of pediatric refractory nephrotic syndrome and frequency.