Systemic vasculitis involving the kidney: the nephropathologist's point of view.

Kidneys are often targets of systemic vasculitis (SVs), being affected in many different forms and representing a possible sentinel of an underlying multi-organ condition. Renal biopsy still remains the gold standard for the identification, characterization and classification of these diseases, solving complex differential diagnosis thanks to the combined application of light microscopy (LM), immunofluorescence (IF) and electron microscopy (EM). Due to the progressively increasing complexity of renal vasculitis classification systems (e.g. pauci-immune vs immune complex related forms), a clinico-pathological approach is mandatory and adequate technical and interpretative expertise in nephropathology is required to ensure the best standard of care for our patients. In this complex background, the present review aims at summarising the current knowledge and challenges in the world of renal vasculitis, unveiling the potential role of the introduction of digital pathology in this setting, from the creation of hub-spoke networks to the future application of artificial intelligence (AI) tools to aid in the diagnostic and scoring/classification process.

Inducible deletion of microRNA activity in kidney mesenchymal cells exacerbates renal fibrosis.

MicroRNAs (miRNAs) are sequence-specific inhibitors of post-transcriptional gene expression. However, the physiological functions of these non-coding RNAs in renal interstitial mesenchymal cells remain unclear. To conclusively evaluate the role of miRNAs, we generated conditional knockout (cKO) mice with platelet-derived growth factor receptor-ß (PDGFR-ß)-specific inactivation of the key miRNA pathway gene Dicer. The cKO mice were subjected to unilateral ureteral ligation, and renal interstitial fibrosis was quantitatively evaluated using real-time polymerase chain reaction and immunofluorescence staining. Compared with control mice, cKO mice had exacerbated interstitial fibrosis exhibited by immunofluorescence staining and mRNA expression of PDGFR-ß. A microarray analysis showed decreased expressions of miR-9-5p, miR-344g-3p, and miR-7074-3p in cKO mice compared with those in control mice, suggesting an association with the increased expression of PDGFR-ß. An analysis of the signaling pathways showed that the major transcriptional changes in cKO mice were related to smooth muscle cell differentiation, regulation of DNA metabolic processes and the actin cytoskeleton, positive regulation of fibroblast proliferation and Ras protein signal transduction, and focal adhesion-PI3K/Akt/mTOR signaling pathways. Depletion of Dicer in mesenchymal cells may downregulate the signaling pathway related to miR-9-5p, miR-344g-3p, and miR-7074-3p, which can lead to the progression of chronic kidney disease. These findings highlight the possibility for future diagnostic or therapeutic developments for renal fibrosis using miR-9-5p, miR-344g-3p, and miR-7074-3p.

Comparison of Complications between Total Intravenous Anaesthesia and Combined Intravenous and Inhalation Anaesthesia after Renal Biopsy in Children.

OBJECTIVE: The objective of this study was to examine the influence of total intravenous anaesthesia (TIVA) compared to combined intravenous and inhalation anaesthesia (CIIA) in paediatric patients undergoing renal biopsy. METHODS: A total of 86 children with nephrotic syndrome, acute glomerulonephritis, chronic glomerulonephritis, IgG nephropathy, systemic lupus erythematosus and purpura nephritis were selected from January 2018 to January 2023 in our hospital. All children were divided into the total intravenous anaesthesia group and intravenous inhalational anaesthesia group according to the anaesthesia method. The experimental group comprised 46 children with renal diseases who underwent static aspiration compound anaesthesia during renal biopsy at our hospital from January 2018 to January 2023. Conversely, the control group included 40 children with renal diseases who underwent total intravenous anaesthesia during renal biopsy at the hospital within the same period. Hemodynamic parameters, such as mean arterial pressure (MAP), heart rate (HR), and oxygen saturation (SPO2), were assessed at four different time points: Before anesthesia induction (T0), during anesthesia induction (T1), after anesthesia induction (T2), and at the conclusion of the surgery (T3). Puncture success rate, time to renal puncture, time to get out of bed, postoperative recovery from anaesthesia (including time to postoperative awakening and time to return to spontaneous respiration) and incidence of adverse anaesthetic reactions were also included. RESULTS: We observed notable variations in HR and MAP at T2 and T3, as well as SPO2 levels, duration of awakening from anaesthesia and time taken to resume spontaneous respiration between the two groups at T2 (p < 0.05). No statistically significant variances were detected between the two groups concerning adverse reactions to anaesthesia, puncture success rate, duration to renal puncture and time to mobilisation from bed (p > 0.05). CONCLUSIONS: In conclusion, compared with the total intravenous anaesthesia, the implementation of the sedation-aspiration-combined anaesthesia in renal biopsy in children with renal disease features less haemodynamic fluctuation, better postoperative anaesthesia recovery and does not increase the incidence of adverse reactions.

Mesenchymal stem cells pretreated with interferon-gamma attenuate renal fibrosis by enhancing regulatory T cell induction.

Mesenchymal stem cells (MSCs) exert their anti-inflammatory and anti-fibrotic effects by secreting various humoral factors. Interferon-gamma (IFN-γ) can enhance these effects of MSCs, and enhancement of regulatory T (Treg) cell induction is thought to be an underlying mechanism. However, the extent to which Treg cell induction by MSCs pretreated with IFN-γ (IFN-γ MSCs) ameliorates renal fibrosis remains unknown. In this study, we investigated the effects of Treg cell induction by IFN-γ MSCs on renal inflammation and fibrosis using an siRNA knockdown system. Administration of IFN-γ MSCs induced Treg cells and inhibited infiltration of inflammatory cells in ischemia reperfusion injury (IRI) rats more drastically than control MSCs without IFN-γ pretreatment. In addition, administration of IFN-γ MSCs more significantly attenuated renal fibrosis compared with control MSCs. Indoleamine 2,3-dioxygenase (IDO) expression levels in conditioned medium from MSCs were enhanced by IFN-γ pretreatment. Moreover, IDO1 knockdown in IFN-γ MSCs reduced their anti-inflammatory and anti-fibrotic effects in IRI rats by reducing Treg cell induction. Our findings suggest that the increase of Treg cells induced by enhanced secretion of IDO by IFN-γ MSCs played a pivotal role in their anti-fibrotic effects. Administration of IFN-γ MSCs may potentially be a useful therapy to prevent renal fibrosis progression.

Clinicopathological characteristics and prognosis in patients with monoclonal gammopathy and renal damage in central China: a multicenter retrospective cohort study.

Renal involvement is common in monoclonal gammopathy (MG); however, the same patient may have both MG and non-paraprotein-associated renal damage. Accordingly, distinguishing the cause of renal damage is necessary because of the different clinical characteristics and associated treatments. In this multicenter retrospective cohort study, we described the clinicopathological characteristics and prognosis of 703 patients with MG and renal damage in central China. Patients were classified as having MG of renal significance (MGRS), MG of undetermined significance (MGUS), or hematological malignancy. 260 (36.98%), 259 (36.84%), and 184 (26.17%) had MGRS, MGUS, and hematological malignancies, respectively. Amyloidosis was the leading pattern of MGRS (74.23%), followed by thrombotic microangiopathy (8.85%) and monoclonal immunoglobulin deposition disease (8.46%). Membranous nephropathy was the leading diagnosis of MGUS (39.38%). Renal pathological findings of patients with hematological malignancies included paraprotein-associated lesions (84.78%) and non-paraprotein-associated lesions (15.22%). The presence of nephrotic syndrome and an abnormal free light chain (FLC) ratio were independently associated with MGRS. The overall survival was better in patients with MGUS than in those with MGRS or hematological malignancies.

Clinicopathological characteristics and gene mutations in 11 patients with lipoprotein glomerulopathy.

OBJECTIVE: Lipoprotein glomerulopathy (LPG) is a rare disorder characterized by the development of glomerular lipoprotein thrombosis. LPG exhibits familial aggregation, with mutations in the apolipoprotein E (APOE) gene identified as the leading cause of this disease. This study aimed to investigate APOE gene mutations and the clinicopathological features in eleven LPG patients. METHODS: Clinicopathological and follow-up data were obtained by extracting DNA, followed by APOE coding region sequencing analysis. This study analyzed clinical and pathological manifestations, gene mutations, treatment and prognosis. RESULTS: The mean age of the eleven patients was 33.82 years. Among them, five had a positive family history for LPG, ten presented with proteinuria, four exhibited nephrotic syndrome, and six presented with microscopic hematuria. Dyslipidemia was identified in ten patients. In all renal specimens, there was evident dilation of glomerular capillary lumens containing lipoprotein thrombi, and positive oil red O staining was observed in frozen sections of all samples. APOE gene testing revealed that one patient had no mutations, while the remaining ten patients exhibited mutations in the APOE gene, with three patients presenting with multiple mutations simultaneously. Following the confirmation of LPG diagnosis, treatment with angiotensin-converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) was initiated, and the disease progressed slowly. CONCLUSION: LPG is histologically characterized by lamellated lipoprotein thrombi in glomeruli, and kidney biopsy is essential for diagnosis. Mutations in the APOE gene are the leading cause of LPG. This study revealed clinicopathological characteristics and APOE gene mutations in patients with LPG, which helps us better understand the disease.

Renal macrophages induce hypertension and kidney fibrosis in Angiotensin II salt mice model.

The immune system is involved in hypertension development with different immune cells reported to have either pro or anti-hypertensive effects. In hypertension, immune cells have been thought to infiltrate blood pressure-regulating organs, resulting in either elevation or reduction of blood pressure. There is controversy over whether macrophages play a detrimental or beneficial role in the development of hypertension, and the few existing studies have yielded conflicting results. This study aimed to determine the effects of angiotensin II (Ang II) salt-induced hypertension on renal immune cells and to determine whether renal macrophages are involved in the induction of hypertension. Hypertension was induced by administration of Ang II and saline for two weeks. The effects of hypertension on kidney immune cells were assessed using flow cytometry. Macrophage infiltration in the kidney was assessed by immunohistochemistry and kidney fibrosis was assessed using trichrome stain and kidney real time-qPCR. Liposome encapsulated clodronate was used to deplete macrophages in C57BL/6J mice and investigate the direct role of macrophages in hypertension induction. Ang II saline mice group developed hypertension, had increased renal macrophages, and had increased expression of Acta2 and Col1a1 and kidney fibrotic areas. Macrophage depletion blunted hypertension development and reduced the expression of Acta2 and Col1a1 in the kidney and kidney fibrotic areas in Ang II saline group. The results of this study demonstrate that macrophages infiltrate the kidneys and increase kidney fibrosis in Ang II salt-induced hypertension, and depletion of macrophages suppresses the development of hypertension and decreases kidney fibrosis. This indicates that macrophages play a direct role in hypertension development. Hence macrophages have a potential to be considered as therapeutic target in hypertension management.

Comparative analysis of ultrasound-guided percutaneous biopsy of native kidneys in children and adults using the free-flank supine antero-lateral decubitus positioning.

PURPOSE: Ultrasound-guided percutaneous biopsy (USPB) of the native kidneys is the preferred diagnostic method for several nephrological conditions in both adult and pediatric populations. Conventionally, native kidney biopsies are conducted with patients in the prone position (PP). However, an alternative approach involving the supine oblique antero-lateral position (SALP) has been explored, particularly for individuals who are obese, elderly, or critically ill. METHODS: This study aimed to assess the feasibility and outcomes of USPB performed in SALP with a Free-Flank setting (FF-SALP) in pediatric patients (Group A) compared to adults (Group B). Data from kidney biopsies conducted between 2008 and 2021 were gathered. The study focused on the safety and the prevalence of biopsy samples containing a minimum of 10 glomeruli, histopathological yield in both groups. RESULTS: Complication rates were low in both groups (5.6% vs. 3.7%; p = 0.454), without major complications noted. The pediatric group achieved a significantly higher mean number of glomeruli per biopsy compared to the adult group (20.6 ± 12.3 vs. 15.7 ± 9.4; p < 0.001). However, when evaluating the minimum threshold of 10 glomeruli (76.3% vs. 68.5%; p = 0.072) and histopathologic yield (95.3% vs. 93.5%; p = 0.408), no differences were observed between groups. CONCLUSION: USPB of native kidneys in the FF-SALP position is a safe and effective method for tissue sampling in patients with parenchymal disease. It demonstrated comparable diagnostic yields and complication rates in the pediatric and adult populations, providing advantages in terms of airway management, making it particularly useful for pediatric patients that require general anesthesia.

Myofibroblast-derived exosomes enhance macrophages to myofibroblasts transition and kidney fibrosis.

A critical event in the pathogenesis of kidney fibrosis is the transition of macrophages into myofibroblasts (MMT). Exosomes play an important role in crosstalk among cells in the kidney and the development of renal fibrosis. However, the role of myofibroblast-derived exosomes in the process of MMT and renal fibrosis progression remains unknown. Here, we examined the role of myofibroblast-derived exosomes in MMT and kidney fibrogenesis. In vitro, transforming growth factor-ß1 stimulated the differentiation of kidney fibroblasts into myofibroblasts and promoted exosome release from myofibroblasts. RAW264.7 cells were treated with exosomes derived from myofibroblasts. We found purified exosomes from myofibroblasts trigger the MMT. By contrast, inhibition of exosome production with GW4869 or exosome depletion from the conditioned media abolished the ability of myofibroblasts to induce MMT. Mice treatment with myofibroblast-derived exosomes (Myo-Exo) exhibited severe fibrotic lesion and more abundant MMT cells in kidneys with folic acid (FA) injury, which was negated by TANK-banding kinase-1 inhibitor. Furthermore, suppression of exosome production reduced collagen deposition, extracellular matrix protein accumulation, and MMT in FA nephropathy. Collectively, Myo-Exo enhances the MMT and kidney fibrosis. Blockade of exosomes mediated myofibroblasts-macrophages communication may provide a novel therapeutic target for kidney fibrosis.

Reproducibility and prognostic ability of chronicity parameters in kidney biopsy - Comprehensive evaluation comparing microscopy and artificial intelligence in digital pathology.

INTRODUCTION: Semi-quantitative scoring of various parameters in renal biopsy is accepted as an important tool to assess disease activity and prognostication. There are concerns on the impact of interobserver variability in its prognostic utility, generating a need for computerized quantification. METHODS: We studied 94 patients with renal biopsies, 45 with native diseases and 49 transplant patients with index biopsies for Polyomavirus nephropathy. Chronicity scores were evaluated using two methods. A standard definition diagram was agreed after international consultation and four renal pathologists scored each parameter in a double-blinded manner. Interstitial fibrosis (IF) score was assessed with five different computerized and AI-based algorithms on trichrome and PAS stains. RESULTS: There was strong prognostic correlation with renal function and graft outcome at a median follow-up ranging from 24 to 42 months respectively, independent of moderate concordance for pathologists scores. IF scores with two of the computerized algorithms showed significant correlation with estimated glomerular filtration rate (eGFR) at biopsy but not at the end of follow-up. There was poor concordance for AI based platforms. CONCLUSION: Chronicity scores are robust prognostic tools despite interobserver reproducibility. AI-algorithms have absolute precision but are limited by significant variation when different hardware and software algorithms are used for quantification.

Iguratimod prevents renal fibrosis in unilateral ureteral obstruction model mice by suppressing M2 macrophage infiltration and macrophage-myofibroblast transition.

Iguratimod is a novel synthetic, small-molecule immunosuppressive agent used to treat rheumatoid arthritis. Through ongoing exploration of its role and mechanisms of action, iguratimod has been observed to have antifibrotic effects in the lung and skin; however, its effect on renal fibrosis remains unknown. This study aimed to investigate whether iguratimod could affect renal fibrosis progression. Three different concentrations of iguratimod (30 mg/kg/day, 10 mg/kg/day, and 3 mg/kg/day) were used to intervene in unilateral ureteral obstruction (UUO) model mice. Iguratimod at 10 mg/kg/day was observed to be effective in slowing UUO-mediated renal fibrosis. In addition, stimulating bone marrow-derived macrophages with IL-4 and/or iguratimod, or with TGF-ß and iguratimod or SRC inhibitors in vitro, suggested that iguratimod mitigates the progression of renal fibrosis in UUO mice, at least in part, by inhibiting the IL-4/STAT6 signaling pathway to attenuate renal M2 macrophage infiltration, as well as by impeding SRC activation to reduce macrophage-myofibroblast transition. These findings reveal the potential of iguratimod as a treatment for renal disease.

Microvesicles from Mesenchymal Stem Cells Overexpressing MiR-34a Ameliorate Renal Fibrosis In Vivo.

INTRODUCTION: We recently discovered that microvesicles (MVs)  derived from mesenchymal stem cells (MSCs) overexpressing  miRNA-34a can alleviate experimental kidney injury in mice. In  this study, we further explored the effects of miR34a-MV on renal  fibrosis in the unilateral ureteral obstruction (UUO) models.  Methods. Bone marrow MSCs were modified by lentiviruses  overexpressing miR-34a, and MVs were collected from the  supernatants of MSCs. C57BL6/J mice were divided into control,  unilateral ureteral obstruction (UUO), UUO + MV, UUO + miR-34aMV and UUO + miR-34a-inhibitor-MV groups. MVs were injected  to mice after surgery. The mice were then euthanized on day 7  and 14 of modeling, and renal tissues were collected for further  analyses by Hematoxylin and eosin, Masson's trichrome,  and Immunohistochemical (IHC) staining.  Results. The UUO + MV group exhibited a significantly reduced  degree of renal interstitial fibrosis with inflammatory cell infiltration,  tubular epithelial cell atrophy, and vacuole degeneration compared  with the UUO group. Surprisingly, overexpressing miR-34a enhanced  these effects of MSC-MV on the UUO mice.  Conclusion. Our study demonstrates that miR34a further enhances  the effects of MSC-MV on renal fibrosis in mice through the  regulation of epithelial-to-mesenchymal transition (EMT) and  Notch pathway. miR-34a may be a candidate molecular therapeutic  target for the treatment of renal fibrosis. DOI: 10.52547/ijkd.7673.

Butylparaben induced zebrafish (Danio rerio) kidney injury by down-regulating the PI3K-AKT pathway.

Butylparaben, a common endocrine disruptor in the environment, is known to be toxic to the reproductive system, heart, and intestines, but its nephrotoxicity has rarely been reported. In order to study the nephrotoxicity and mechanism of butylparaben, we examined the acute and chronic effects on human embryonic kidney cells (HEK293T) and zebrafish. Additionally, we assessed the potential remedial effects of salidroside against butylparaben-induced nephrotoxicity. Our in vitro findings demonstrated oxidative stress and cytotoxicity to HEK293T cells caused by butylparaben. In the zebrafish model, the concentration of butylparaben exposure ranged from 0.5 to 15 µM. An assortment of experimental techniques was employed, including the assessment of kidney tissue morphology using Hematoxylin-Eosin staining, kidney function analysis via fluorescent dextran injection, and gene expression studies related to kidney injury, development, and function. Additionally, butylparaben caused lipid peroxidation in the kidney, thereby damaging glomeruli and renal tubules, which resulted from the downregulation of the PI3K-AKT signaling pathway. Furthermore, salidroside ameliorated butylparaben-induced nephrotoxicity through the PI3K-AKT signaling pathway. This study reveals the seldom-reported kidney toxicity of butylparaben and the protective effect of salidroside against toxicological reactions related to nephrotoxicity. It offers valuable insights into the risks to kidney health posed by environmental toxins.

Telmisartan ameliorates nephropathy and restores the hippo pathway in rats with metabolic syndrome.

The main objective of this study was to determine if the telmisartan-ameliorative effects of metabolic syndrome (MetS)-evoked nephropathy are attributed to the Hippo pathway. A secondary objective was to investigate the potential of vitamin D3 to enhance telmisartan-favourable effects. A diet composed of 24% fat and 3% salt, along with drinking water containing 10% fructose, was administered for 12 weeks to induce MetS. MetS-rats were given telmisartan (5 mg/kg/day), vitamin D3 (10 µg/kg/day) or both by gavage, starting in the sixth week of experimental diet administration. Assessments performed at closure included renal function, histological examination, catalase, malondialdehyde (MDA), nuclear factor kappa-B (NF-κB), interleukin-6 (IL-6), peroxisome proliferator-activated receptor-γ (PPAR-γ), phosphatase and tensin homolog (PTEN), and transforming growth factor-ß (TGF-ß). Matrix metalloproteinase-9 (MMP-9) immunostaining was conducted. The expression of the Hippo pathway components, as well as that of angiotensin II type 1 and type 2 (AT1 and AT2), receptors was evaluated. Telmisartan attenuated MetS-evoked nephropathy, as demonstrated by improvement of renal function and histological features, enhancement of catalase, reduction of MDA, inflammation (NF-κB, IL-6), and renal fibrosis (increased PPAR-γ and PTEN and reduced MMP-9 and TGF-ß). Telmisartan downregulated AT1-receptor, upregulated AT2-receptor and restored the Hippo pathway. Vitamin D3 replicated most of the telmisartan-elicited effects and enhanced the antifibrotic actions of telmisartan. The alleviative effects of telmisartan on MetS-evoked nephropathy may be related to the restoration of the Hippo pathway. The combination of vitamin D3 and telmisartan exerted more favourable effects on metabolic and nephropathic biomarkers compared with either one administered alone.

Percutaneous kidney biopsies in children: a 24-year review in a tertiary center in northern Portugal.

INTRODUCTION: Percutaneous kidney biopsy (KB) is crucial to the diagnosis and management of several renal pathologies. National data on native KB in pediatric patients are scarce. We aimed to review the demographic and clinical characteristics and histopathological patterns in children who underwent native percutaneous KB over 24 years. METHODS: Retrospective observational study of patients undergoing native percutaneous KB in a pediatric nephrology unit between 1998 and 2021, comparing 3 periods: period 1 (1998-2005), period 2 (2006-2013), and period 3 (2014-2021). RESULTS: We found that 228 KB were performed, 78 (34.2%) in period 1, 91 (39.9%) in period 2, and 59 (25.9%) in period 3. The median age at KB was 11 (7-14) years. The main indications for KB were nephrotic syndrome (NS) (42.9%), hematuria and/or non-nephrotic proteinuria (35.5%), and acute kidney injury (13.2%). Primary glomerulopathies were more frequent (67.1%), particularly minimal change disease (MCD) (25.4%), IgA nephropathy (12.7%), and mesangioproliferative glomerulonephritis (GN) (8.8%). Of the secondary glomerulopathies, lupus nephritis (LN) was the most prevalent (11.8%). In group 1, hematuria and/or non-nephrotic proteinuria were the main reasons for KB, as opposed to NS in groups 2 and 3 (p < 0.01). LN showed an increasing trend (period 1-3: 2.6%-5.3%) and focal segmental glomerular sclerosis (FSGS) showed a slight decreasing trend (period 1-3: 3.1%-1.8%), without statistical significance. CONCLUSIONS: The main indication for KB was NS, which increased over time, justifying the finding of MCD as main histological diagnosis. LN showed an increase in incidence over time, while FSGS cases did not increase.

Nlrp2 deletion ameliorates kidney damage in a mouse model of cystinosis.

Cystinosis is a rare autosomal recessive disorder caused by mutations in the CTNS gene that encodes cystinosin, a ubiquitous lysosomal cystine/H+ antiporter. The hallmark of the disease is progressive accumulation of cystine and cystine crystals in virtually all tissues. At the kidney level, human cystinosis is characterized by the development of renal Fanconi syndrome and progressive glomerular and interstitial damage leading to end-stage kidney disease in the second or third decade of life. The exact molecular mechanisms involved in the pathogenesis of renal disease in cystinosis are incompletely elucidated. We have previously shown upregulation of NLRP2 in human cystinotic proximal tubular epithelial cells and its role in promoting inflammatory and profibrotic responses. Herein, we have investigated the role of NLRP2 in vivo using a mouse model of cystinosis in which we have confirmed upregulation of Nlrp2 in the renal parenchyma. Our studies show that double knock out Ctns-/- Nlrp2-/- animals exhibit delayed development of Fanconi syndrome and kidney tissue damage. Specifically, we observed at 4-6 months of age that animals had less glucosuria and calciuria and markedly preserved renal tissue, as assessed by significantly lower levels of inflammatory cell infiltration, tubular atrophy, and interstitial fibrosis. Also, the mRNA expression of some inflammatory mediators (Cxcl1 and Saa1) and the rate of apoptosis were significantly decreased in 4-6-month old kidneys harvested from Ctns-/- Nlrp2-/- mice compared to those obtained from Ctns-/-mice. At 12-14 months of age, renal histological was markedly altered in both genetic models, although double KO animals had lower degree of polyuria and low molecular weight proteinuria and decreased mRNA expression levels of Il6 and Mcp1. Altogether, these data indicate that Nlrp2 is a potential pharmacological target for delaying progression of kidney disease in cystinosis.

Determinants of non-diabetic kidney diseases in type 2 diabetic patients: Twenty years of single center experience.

BACKGROUND: Diabetic nephropathy is one of the most common complications associated with diabetes. However, non-diabetic kidney disease has been reported in patients with type 2 diabetes at varying incidence rates. The objective of our study is to investigate the occurrence, clinicopathological characteristics, and inflammatory markers linked to diabetic and non-diabetic nephropathy (NDN) in patients with type 2 diabetes mellitus (DM). Additionally, we aimed to explore the possibility of identifying non-diabetic pathology using different biopsy indications. MATERIALS AND METHODS: A total of 159 patients with type 2 DM who underwent renal biopsy at a tertiary care nephrology clinic between January 2000 and January 2022 were enrolled in the study. We collected comprehensive data, including patient demographics, co-morbidities, diabetes duration, renal biopsy indications and results, serological markers, renal function, diabetic retinopathy (DRP), full blood count, blood biochemistry, urinalysis, and inflammatory markers. Patients were categorized based on their biopsy indications, and their biopsy results were classified into three groups: isolated NDN, isolated diabetic nephropathy (DN), and mixed nephropathy with concurrent NDN. We evaluated the relationship between biopsy indications and accompanying pathologies and statistically assessed the likelihood of each biopsy indication detecting non-diabetic renal pathology. Additionally, differences in other data, including demographic and laboratory results and medical histories, among the three groups were investigated. RESULTS: The most frequent indication of renal biopsy was atypical presentations of nephrotic syndrome or nephrotic range proteinuria (ANS/ANP) in 25.1% of patients. Other indications included unexplained renal failure (URF) in 22.6%, atypical presentations of non-nephrotic range proteinuria (ANNP) in 18.2%, acute kidney injury or rapidly progressive kidney dysfunction (AKI/RPKD) in 16.9%, microscopic hematuria in 15.7%, URF with ANNP in 11.3%, and severe nephrotic range proteinuria (SNP) in 9.4%. Renal biopsy revealed isolated NDN in 64.8%, DN in 25.1%, and mixed nephropathy in 10.1% of patients. Primary glomerular diseases were the main non-diabetic renal pathology, predominantly focal segmental glomerulosclerosis (FSGS) (36.4%) followed by MN (10.6%) and IgA nephropathy (7.5%). In comparison with the isolated DN and mixed nephropathy groups, patients in the isolated NDN group had significantly shorter diabetes duration, fewer DRP, as well as lower serum creatinine and neutrophil-to-lymphocyte ratio (NLR). Multivariate logistic regression analysis revealed that presence of hematuria (OR 4.40; 95% CI 1.34 - 14.46, p = 0.014), acute nephrotic range proteinuria (OR 11.93; 95% CI 1.56 - 90.77, p = 0.017), and AKI/APKD (OR 41.08; 95% CI 3.40 - 495.39, p = 0.003) were strong predictors of NDN. Lower NLR (OR 0.77; 95% CI 0.60 - 0.98, p = 0.035), shorter duration of diabetes (OR 0.90; 95% CI 0.84 - 0.97, p = 0.010), and absence of DRP (OR 0.35; 95% CI 0.12 - 0.98, p = 0.046) were also found to be independent indicators of NDN. Receiver operating characteristic curve (ROC) analysis revealed a cut-off value of ≤ 3.01 for NLR (sensitivity of 63.1%, specificity of 63.5%) with regards to predicting non-diabetic renal pathology (p = 0.006). CONCLUSION: Renal biopsy findings in patients with type 2 DM highlight that the prevalence of NDN may be higher than assumed, as presented mainly in the form of primary glomerular disease. The presence of AKI/RPKD, hematuria, and ANS/ANP serves as a reliable indicator of non-diabetic renal pathology. In more ambiguous situations, factors such as a shorter duration of diabetes, absence of DRP, and a lower NLR value may assist clinicians in biopsy decision.

Obesity-related glomerulopathy: recent advances in inflammatory mechanisms and related treatments.

Obesity-related glomerulopathy, which is an obesity-triggered kidney damage, has become a significant threat to human health. Several studies have recently highlighted the critical role of inflammation in obesity-related glomerulopathy development. Additionally, excess adipose tissue and adipocytes in patients with obesity produce various inflammatory factors that cause systemic low-grade inflammation with consequent damage to vascular endothelial cells, exacerbating glomerular injury. Therefore, we conducted a comprehensive review of obesity-related glomerulopathy and addressed the critical role of obesity-induced chronic inflammation in obesity-related glomerulopathy pathogenesis and progression, which leads to tubular damage and proteinuria, ultimately impairing renal function. The relationship between obesity and obesity-related glomerulopathy is facilitated by a network of various inflammation-associated cells (including macrophages, lymphocytes, and mast cells) and a series of inflammatory mediators (such as tumor necrosis factor α, interleukin 6, leptin, adiponectin, resistin, chemokines, adhesion molecules, and plasminogen activator inhibitor 1) and their inflammatory pathways. Furthermore, we discuss a recently discovered relationship between micronutrients and obesity-related glomerulopathy inflammation and the important role of micronutrients in the body's anti-inflammatory response. Therefore, assessing these inflammatory molecules and pathways will provide a strong theoretical basis for developing therapeutic strategies based on anti-inflammatory effects to prevent or delay the onset of kidney injury.

Mice with a Pax2 missense variant display impaired glomerular repair.

PAX2 regulates kidney development, and its expression persists in parietal epithelial cells (PECs), potentially serving as a podocyte reserve. We hypothesized that mice with a Pax2 pathogenic missense variant (Pax2A220G/+) have impaired PEC-mediated podocyte regeneration. Embryonic wild-type mouse kidneys showed overlapping expression of PAX2/Wilms' tumor-1 (WT-1) until PEC and podocyte differentiation, reflecting a close lineage relationship. Embryonic and adult Pax2A220G/+ mice have reduced nephron number but demonstrated no glomerular disease under baseline conditions. Pax2A220G/+ mice compared with wild-type mice were more susceptible to glomerular disease after adriamycin (ADR)-induced podocyte injury, as demonstrated by worsened glomerular scarring, increased podocyte foot process effacement, and podocyte loss. There was a decrease in PAX2-expressing PECs in wild-type mice after adriamycin injury accompanied by the occurrence of PAX2/WT-1-coexpressing glomerular tuft cells. In contrast, Pax2A220G/+ mice showed no changes in the numbers of PAX2-expressing PECs after adriamycin injury, associated with fewer PAX2/WT-1-coexpressing glomerular tuft cells compared with injured wild-type mice. A subset of PAX2-expressing glomerular tuft cells after adriamycin injury was increased in Pax2A220G/+ mice, suggesting a pathological process given the worse outcomes observed in this group. Finally, Pax2A220G/+ mice have increased numbers of glomerular tuft cells expressing Ki-67 and cleaved caspase-3 compared with wild-type mice after adriamycin injury, consistent with maladaptive responses to podocyte loss. Collectively, our results suggest that decreased glomerular numbers in Pax2A220G/+ mice are likely compounded with the inability of their mutated PECs to regenerate podocyte loss, and together these two mechanisms drive the worsened focal segmental glomerular sclerosis phenotype in these mice.NEW & NOTEWORTHY Congenital anomalies of the kidney and urinary tract comprise some of the leading causes of kidney failure in children, but our previous study showed that one of its genetic causes, PAX2, is also associated with adult-onset focal segmental glomerular sclerosis. Using a clinically relevant model, our present study demonstrated that after podocyte injury, parietal epithelial cells expressing PAX2 are deployed into the glomerular tuft to assist in repair in wild-type mice, but this mechanism is impaired in Pax2A220G/+ mice.