Tubular Interstitial Fibrosis Research Articles

#648 Relationship between renal tubular damage, interstitial fibrosis and semaphorin class 3C

Abstract Background and Aims The detailed mechanism of interstitial fibrosis in CKD has not been clarified. In this study, we focused on semaphorin class 3C (SEMA3C), a secreted protein expressed in the renal tubules, that is involved in embryonic kidney development [1], and investigated the relationship between SEMA3C and renal tubular damage and interstitial fibrosis. Methods < Clinical research> We investigated the correlation between serum SEMA3C concentration and the renal tubular damage marker urinary β2 microglobulin (β2MG) concentration in the 191 patients who underwent kidney biopsy from 2017 to 2021 at Yamagata University. < In vivo study> We generated proximal tubule-specific SEMA3C knockout mice (PT-SEMA3C KO) from male mice (C57BL/6) using the Cre/loxP system. The PT-SEMA3C KO group and control group were fed a 0.2% adenine diet for 5 weeks to induce CKD. The area of interstitial fibrosis/tubular atrophy (IFTA) region was assessed by Masson-Trichrome staining. Results < Clinical research> The median age of the patients was 54 (IQR 38-68) years, 94 men and 97 women. Median serum SEMA3C concentration was 0.14 (IQR 0.07-0.35) ng/ml. Median urinary β2MG levels was 0.22 (IQR 0-1.79) mg/gCr. Spearman's correlation analysis showed a significant negative correlation between serum SEMA3C and urinary β2MG levels (r=-0.208, P=0.005), but no correlation between eGFR and Urinary protein/ creatinine. < In vivo study> IFTA region was 5.6% in the control group, compared to 11.2% in the PT-SEMA3C KO group (p=0.031). Interstitial fibrosis was significantly suppressed in the PT-SEMA3C KO mice (Fig. 1). Conclusion Our clinical and in vivo results indicate that serum SEMA3C is associated with renal tubular damage and interstitial fibrosis.

#1803 Is class II lupus nephritis as benign as one thinks?

Abstract Background and Aims The classification of Lupus Nephritis (LN) plays a pivotal role in determining prognosis and guiding treatment, aligning with ISN/RPS recommendations. KDIGO and EULAR advocate for immunosuppression in cases of proliferative LN (Class III/IV) and Class V with nephrotic syndrome, while “non-proliferative” instances (Class I and II) are advised conservative care. In a contrasting approach, GLOSEN recommends immunosuppression for Class II if persistent proteinuria exceeds 1g. ISN/RPS suggests incorporating activity and chronicity indexes to further refine the classification of LN. Concerns surrounding immunosuppression in LN Class II arise from its favorable long-term kidney survival and potential drug toxicity. However, the need for caution is underscored by a 30–50% class transformation rate. Limited research comparing the long-term prognosis of treated and untreated patients exists due to the gradual progression of the disease. The use of Activity (NIH-A) and Chronicity (NIH-C) indexes, particularly in the context of protocol biopsies, offers an opportunity to reassess the perceived benign nature of LN Class II. Method In this single-center investigation, patients diagnosed with LN belonging to Class II or II+V from 1999 to 2021 were examined. Biopsies were classified according to ISN/RPS criteria and evaluated using the NIH-A and NIH-C Indexes. Patients previously diagnosed with Class III/IV LN and those experiencing class transformation to a proliferative class were excluded. We present the findings in a descriptive manner. Results Sixteen patients, with a median age of 38.5 (12 female), were included. Histological findings from the initial biopsies revealed a NIH-A of 0, with NIH-C exceeding 0 in 31% (5/16) cases. Six patients exhibited Class II plus V, with varying NIH-C scores. The primary contributors to NIH-C in the initial biopsies were tubular atrophy and interstitial fibrosis. Ten patients underwent a second biopsy after an average time lapse of 39 months (7-101). The decision for most second biopsies was based on clinical judgment rather than a standardized protocol. One patient initially diagnosed with Class II+V displayed Class II on the second biopsy, and vice versa. In 70% of patients the NIH-C increased, primarily driven by glomerulosclerosis. The rise in NIH-C scores was observed in 3/6 patients with Class II+V and in all 4 patients with isolated Class II. Most patients received mycophenolate, and 3 were treated with low-dose prednisolone. The clinical and histologic characteristics of the 10 patients who underwent a second biopsy are outlined in Tables 1 and 2. Conclusion Our limited, biased study raises questions rather than providing definitive evidence. The consistent NIH-C rise challenges Class II LN perceived benign nature. It is plausible that not all LN Class II cases are equivalent and histological variances, such as mesangial proliferation, or its focal or diffuse distribution impact outcomes. Histological variations and treatment impact on LN Class II warrant further investigation.

#1449 Maturation of tertiary lymphoid structures in progressive kidney damage due to chronic phosphate load

Abstract Background and Aims We have recently shown that a high phosphate diet (HPD) in mice leads to an increase in FGF23 levels and causes progressive tubular damage and interstitial fibrosis with increased accumulation of macrophages and concomitant perivascular immune cell aggregates in the corticomedullary zone. Such tertiary lymphoid structures (TLS) can develop as a result of chronic inflammation and have already been described in lupus nephritis and IgA nephropathy, among others. In our model, the question arose to what extent damage to the proximal tubule is temporally associated with the development and maturation of TLS and which factors favor TLS development. Method Wild-type mice were fed HPD for 1, 2, 3, 4 and 6 months and the kidneys of each were compared with those of mice on a normal phosphate diet (NPD). To evaluate the effect of high FGF23 ± phosphate, Fgf23 was overexpressed in mice on NPD and HPD using an adeno-associated virus (AAV-Fgf23), and hypophosphatemic Hyp mice were used. Results An increased tubular damage score was seen after only two months of HPD. In parallel, perivascular immune cell clusters developed in the corticomedullary zone and in the renal cortex, which were characterized by aggregates of CD45R+ B cells and CD3+ T cells, as well as LYVE1+ lymphatic vessels after three months of HPD and were accompanied by increased expression of venous markers (Plvap, Aplnr, EphB4) and cell adhesion molecules (Sell, Vcam1, Madcam1). Further analyses showed a time-dependent induction of the immunofibroblast-derived chemokines Cxcl13 and Ccl19, as well as the lymphotoxins Lta and Ltb, which are important for the differentiation of immunofibroblasts into follicular dendritic cells (FDC) and follicular reticular cells (FRC). Already after four months of HPD, proliferating B-cell clusters with FDCs, FRCs located in T-cell clusters, podoplanin+ networks, high endothelial venules, plasma cells and increased IgD synthesis indicated fully mature TLS, while tubular damage and fibrosis continued to increase until six months of HPD. Compared to AAV-Fgf23 mice on NPD, only AAV-Fgf23 animals on HPD developed tubular damage with fibrosis and fully mature TLS. Hypophosphatemic Hyp mice with high FGF23 showed neither signs of tubular damage nor the development of TLS. Conclusion The development of renal TLS due to chronic high phosphate load coincides with the development of tubular damage, with earlier maturation of TLS and progression of tubular damage.

#2257 Kidney outcomes in ANCA-associated vasculitis—application of Berden's Classification and ANCA Renal Risk Score in a single centre cohort

Abstract Background and Aims Anti-neutrophil cytoplasmic antibody (ANCA) -associated vasculitis is the most common cause of rapidly progressive glomerulonephritis and is a life-threatening condition. The course of the disease is variable and disease prognostication remains challenging. Histological and clinical scores have been developed to predict kidney outcomes, to tailor treatment. The aim of this study is to apply Berden´s histopathological classification (BHC) and ANCA renal risk score (ARRS), proposed by Brix and co-workers, in a cohort of patients with ANCA-associated vasculitis and to analyse their performance in renal outcomes prediction. Method In this retrospective observational study, we included patients with biopsy proven ANCA-associated vasculitis, diagnosed at our centre between March 2011 and March 2023. We consulted the clinical records and the kidney biopsy reports. Biopsies were categorized according to both scores. Follow up time was up to 48 months since the date of diagnosis. In BHC patients were divided into 4 groups (focal, crescentic, sclerotic and mixed) according to normal glomeruli, cellular crescents and globally sclerosed glomeruli proportion. When applying the ARRS, patients were divided into 3 groups: low, medium or high risk. This is a histopathological and biochemical score that combines normal glomeruli and tubular atrophy and interstitial fibrosis (IFTA) percentages with estimated glomerular filtration rate (eGFR) at time of diagnosis. Factors related to renal survival were evaluated by Spearman Rank Correlation, Binary Logistic Regression analysis and Kaplan-Meier curves were used for assessing time between diagnosis and end stage kidney disease (ESKD). Results Our study included 31 patients, 54.8% were male, median age at diagnosis was 62 (IQR, 53-69) years, with a median eGFR of 8.3 (IQR, 6.2-13.3) mL/min/1.73 m2 and a median urine albumin to creatinine ratio (uACR) of 1.5 (IQR, 0.88-2.2) g/g. 19 patients (61.3%) were positive for myeloperoxidase and 5 (16.1%) were proteinase 3 positive. Median follow up time was 36 (IQR, 9-48) months. 10 patients (32%) developed ESKD and 9 patients (29%) died. Regarding BHC, 4 patients (13%) presented a focal class, 18 (58%) crescentic, 7 (23%) mixed and 2 (6%) sclerotic. Progression to ESKD occurred in 7 patients with crescentic class (38.9%), 2 patients with mixed (28.6%) and 1 patient with sclerotic (50%). None of the patients with focal class developed ESKD. There were no significant differences in kidney survival curves by BHC class (Log Rank p = 0.47) (Fig. 1a). In ARRS, 1 patient (3%) was in the low-risk group, 19 patients (61%) in the medium risk and 11 patients (35%) in the high risk. Characteristics of the population by ARRS score group and detailed score discrimination are specified in Table 1. Progression to ESKD, occurred in 5 patients of medium risk group (26.3%) and also in 5 patients in the high-risk group which represented 45.5% of this group. Kidney survival curves by ARRS score group had no statistic difference (Log Rank p = 0.46) (Fig. 1b). ESKD was positively associated with serum creatinine (sCr) at admission (p = 0.02), highest sCr (p = 0.001) and leukocyturia (p = 0.05). By multivariate analysis adjusted to gender, age, sCr at admission, leukocyturia and BHC or ARRS, the only factor associated with ESKD was sCr at admission (OR 1.45, CI 1.03-2.06, p = 0.05). Conclusion In our cohort of patients, sCr at patient hospital admission was the best predictor for progression to ESKD. By ARRS, just one patient had low risk, and as expected, kidney survival was higher in the medium risk group (68.5%) than in the high-risk group (53%), although not reaching statistical significance. BHC also had no association with kidney outcomes, although kidney survival was 100% in focal class and sclerotic class had the lowest survival (50%), yet crescentic class revealed a worse kidney survival (57.1%) than mixed class (71.4%). The small number of patients, overall and in each group, and the short follow up period can be pointed as limitations of this study.

#1039 Characteristics and outcome of IgA nephropathy in Switzerland – a single center perspective

Abstract Background and Aims IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide leading to end-stage kidney disease (ESKD) in roughly 40% of affected patients by ten years. Geographic differences in clinical course and response to treatment may partly result from different disease entities. The purpose of this retrospective cohort analysis was to study all cases of IgAN from a single tertiary center with respect to clinical and histological characteristics, treatment practices and outcome. Method This retrospective cohort analysis identified 158 cases of adult biopsy-proven IgAN by chart review diagnosed between 1980 and 2017. Detailed phenotypisation including clinical, paraclinical, histological, treatment and outcome parameters was performed. Remission status was defined as described previously (Reich 2007). Statistical analysis was performed using Excel and SPSS software and included standard descriptive methods and included standard descriptive methods and student's t-test on a significance level of 0.05. Results Subjects were majorly male and of Caucasian descent. Mean estimated glomerular filtration rate (eGFR) according to Chronic Kidney Disease Epidemiology Collaboration formula at diagnosis was 55.3 ml/min/1.73 m2, mean proteinuria was 3.2 g/d. 70.3% of patients were hypertensive at presentation. Clinical presentation varied according to age. Thus, younger patients (18-39 years) presented more frequently with macrohematuria, asymptomatic urine abnormalities and by trend acute kidney injury whereas nephrotic syndrome and extrarenal symptoms were recorded in similar proportions of patients (Fig. 1). 28.5% of initial biopsies showed moderate to severe tubular atrophy and interstitial fibrosis (IFTA), 38% included crescents, 1.9% > 50% crescents. 86.1% of the patients were treated by renin-angiotensin-aldosterone-system inhibitors, 46.8% received immunosuppressive therapy including steroids in 46.2% and other immunosuppressive medications in 19.6% the most common being azathioprine (Fig. 2). There were 33.5% complete and 13.3% partial remissions. Progression to ESKD was noted in 42.1%. 51.4% of patients treated with immunosuppressive therapy experienced remission. Recurrence rate after transplantation was 18.4%. Patients treated by immunosuppressants had higher levels of baseline proteinuria (3.2 ± 2.3 vs. 1.6 ± 1.6 g/d, p < 0.00001), lower baseline eGFR (50 ± 31 vs. 61 ± 30 ml/min/1.73 m2, p = 0.04), higher number of crescents (9.4 ± 15.0 vs 2.3 ± 8.5%, p = 0.001), higher IFTA scores (1.7 ± 0.8 vs. 1.3 ± 0.6, p = 0.007) and higher fluorescence intensity scores for C3 (2.0 ± 0.9 vs. 1.6 ± 0.9, p = 0.02) on initial biopsy as compared to patients treated conservatively. Patients progressing to ESKD presented with higher blood pressure (146 ± 26 vs. 135 ± 18 mmHg systolic, p = 0.005; 89 ± 14 vs. 82 ± 14 mmHg diastolic, p = 0.006), lower eGFR (41 ± 29 vs. 64 ± 28 ml/min/1.73 m2, p = 0.00001), higher levels of proteinuria (3.4 ± 2.0 vs. 1.8 ± 1.9 g/d, p = 0.0001), higher number of crescents (9 ± 17 vs. 4 ± 9%, p = 0.03) and higher IFTA scores (1.8 ± 0.8 vs. 1.3 ± 0.6, p = 0.00001) as compared to patients without ESKD at last follow up. Baseline blood pressure (134 ± 18 vs. 147 ± 26 mmHg systolic, p = 0.004; 82 ± 14 vs. 89 ± 15 mmHg diastolic, p = 0.01), eGFR (60 ± 29 vs. 41 ± 27 mmHg, p = 0.0007), proteinuria (2.3 ± 1.9 vs. 3.2 ± 2.3 g/d, p = 0.03) and severity of IFTA (1.4 ± 0.6 vs. 1.8 ± 0.9, p = 0.003) differed significantly between patients who experienced any remission vs. those who did not achieve remission respectively. Conclusion This analysis gives insight into the characteristics and treatment practices of a Swiss single center cohort of IgAN patients from 1980-2017.

#2615 Altered peroxidasin expression pattern in IgA nephropathy

Abstract Background and Aims PXDN is a multifunctional heme peroxidase responsible for the crosslinking of type IV collagen protomers at basement membranes, playing a crucial role in the extracellular matrix dynamics. In renal pathophysiology, increased PXDN expression has been associated with pro-fibrotic and pro-carcinogenic mechanisms and we have shown that PXDN is expressed throughout all kidney compartments since the early stages of nephrogenesis. However, the role of PXDN in kidney health and disease remains largely unknown. In this work we performed a comparative analysis of PXDN expression between renal biopsy samples from IgA nephropathy (IgAN) patients and healthy kidney biopsy samples. IgAN was the selected CKD model due to its straightforward diagnosis by standard protocols for histopathological evaluation of kidney biopsies, and to the fact that the renal outcomes are consistently associated with several key pathologic features, including tubular atrophy and interstitial fibrosis. Correlations between PXDN expression and IgAN disease and kidney function parameters as well as with ECM proteins were also explored. Method Fluorescence immunohistochemistry for PXDN was performed in biopsy samples from IgAN patients (n = 20) and in biopsies from healthy kidney donors (n = 7). Proximal tubules were assessed by anti-CD15 fluorescent staining. Collagen III (COLIII) deposition was investigated in IgAN samples (n = 7) by immunofluorescence. Brightfield images were manually segmented into glomeruli, proximal and distal tubules, and interstitium, using QuPath software, and the fluorescence intensity measurements were obtained with ImageJ/Fiji. Results Results showed that, in comparison with healthy kidney samples, PXDN is significantly decreased in proximal and distal tubules of IgAN patients (P < 0.001 and P < 0.05, respectively) whereas it is increased in IgAN interstitium (P < 0.001). When IgAN samples were stratified by the presence or absence of chronic lesions (glomerular sclerosis and interstitial fibrosis) we observed that in the proximal tubules, PXDN is decreased even in areas without lesions while in the distal tubules the expression is compromised only in the lesioned areas. In the interstitium, PXDN shows a tendency of increase from healthy tissue to IgAN in areas without and with tubulointerstitial fibrosis, presenting a significant increase in the lesioned areas (P < 0.001). Concerning ECM deposition, results showed a significant correlation between the expression of PXDN and COLIII in sclerotic glomeruli (R = 0.8214; P = 0.0341) and in the tubulointerstitial fibrotic areas (R = 0.93; P = 0.0067). Moreover, although no differences were observed in the glomerular expression of PXDN between healthy and IgAN samples, when considering eGFR, a significant increase of PXDN was observed in both non-lesioned and sclerotic glomeruli from IgAN patients with eGFR bellow 60 ml/min/1,73 m2. In the interstitium, the expression of PXDN was also increased in tubulointerstitial fibrotic areas of IgAN patients with eGFR bellow 60 ml/min/1,73 m2, in comparison with the same areas in patients with higher eGFR values. Conclusions Overall, our study shows a differential expression of PXDN in IgAN, with loss in the tubular region that relates with the state of interstitial fibrosis, and gain in the glomerular and interstitial region where it correlates with COLIII compartment-specific deposition and with kidney function as assessed by eGFR. These data support, for the first time, the enrollment of PXDN in the topographic mechanism of IgA-mediated kidney lesion that deserves further investigations. Given that sclerosis and fibrosis are a common pathogenic mechanism of CKD, irrespective of the underlying etiology, we postulate that PXDN may serve as a novel therapeutic target for this disease.

Linagliptin ameliorates tacrolimus-induced renal injury: role of Nrf2/HO-1 and HIF-1α/CTGF/PAI-1

BackgroundTacrolimus (TAC) is a frequently used immunosuppressive medication in organ transplantation. However, its nephrotoxic impact limits its long-term usage. This study aims to investigate the effect of linagliptin (Lina) on TAC-induced renal injury and its underlying mechanisms.Methods and resultsThirty-two Sprague Dawley rats were treated with TAC (1.5 mg/kg/day, subcutaneously) and/or Lina (5 mg/kg/day, orally) for 4 weeks. Histological examination was conducted, and serum and urinary biomarkers were measured to assess kidney function and integrity. Furthermore, ELISA, Western blot analysis and immunohistochemical assay were employed to determine signaling molecules of oxidative stress, profibrogenic, hypoxic, and apoptotic proteins. Tacrolimus caused renal dysfunction and histological deterioration evidenced by increased serum creatinine, blood urea nitrogen (BUN), urinary cystatin C, and decreased serum albumin as well as elevated tubular injury and interstitial fibrosis scores. Additionally, TAC significantly increased the expression of collagen type-1, alpha-smooth muscle actin (α-SMA), plasminogen activator inhibitor-1 (PAI-1), and transforming growth factor-beta1 (TGF-β1) renal content. Moreover, TAC decreased the expression of nuclear factor erythroid-2-related factor2 (Nrf2), heme oxygenase 1 (HO-1), and mitochondrial superoxide dismutase (SOD2). In addition, TAC increased protein expression of hypoxia-inducible factor1-alpha (HIF-1α), connective tissue growth factor (CTGF), inducible nitric oxide synthase (iNOS), 8-hydroxy-2-deoxyguanosine (8-OHdG), as well as nitric oxide (NO), 4-hydroxynonenal, caspase-3 and Bax renal contents. Furthermore, TAC decreased Bcl-2 renal contents. The Lina administration markedly attenuated these alterations.ConclusionLina ameliorated TAC-induced kidney injury through modulation of oxidative stress, hypoxia, and apoptosis related proteins.

Polyomavirus nephropathy: diagnosis, histologic features, and differentiation from acute rejection.

Polyomaviruses, particularly BK virus, are ubiquitous latent infections that may reactivate with immunosuppression during kidney transplantation, resulting in polyomavirus nephropathy (PVN). The levels of viruria and viremia serve as tools for screening and making a presumptive diagnosis of PVN, respectively, while a definitive diagnosis requires a kidney biopsy. There are histologic classifications of PVN based on the extent of tubular cell viral infection, interstitial fibrosis, and interstitial inflammation. These classifications correlate to some degree with graft function and loss, aiding in determining treatment efficacy and prognostication. PVN has histologic overlap with acute cell-mediated rejection, making the differential diagnosis challenging, although there are suggestive features for these different causes of graft dysfunction. This article reviews the diagnosis, histologic findings, and classifications of PVN, and discusses how to differentiate viral nephropathy from acute rejection.

Hydrangea paniculata coumarins alleviate adriamycin-induced renal lipotoxicity through activating AMPK and inhibiting C/EBPβ

Ethnopharmacological relevanceThroughout Chinese history, Hydrangea paniculata Siebold has been utilized as a traditional medicinal herb to treat a variety of ailments associated to inflammation. In a number of immune-mediated kidney disorders, total coumarins extracted from Hydrangea paniculata (HP) have demonstrated a renal protective effect. Aim of the studyTo investigate renal beneficial effect of HP on experimental Adriamycin nephropathy (AN), and further clarify whether reversing lipid metabolism abnormalities by HP contributes to its renoprotective effect and find out the underlying critical pathways. Materials and methodsAfter establishment of rat AN model, HP was orally administrated for 6 weeks. Biochemical indicators related to kidney injury were determined. mRNAs sequencing using kidney tissues were performed to clarify the underlying mechanism. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis, western blot, molecular docking, and drug affinity responsive target stability (DARTS) assay was carried out to further explore and confirm pivotal molecular pathways and possible target by which HP and 7-hydroxylcoumarin (7-HC) played their renal protection effect via modulating lipid metabolism. ResultsHP could significantly improve renal function, and restore renal tubular abnormal lipid metabolism and interstitial fibrosis in AN. In vitro study demonstrated that HP and its main metabolite 7-HC could reduce ADR-induced intracellular lipid deposition and fibrosis characteristics in renal tubular cells. Mechanically, HP and 7-HC can activate AMP-activated protein kinase (AMPK) via direct interaction, which contributes to its lipid metabolism modulation effect. Moreover, HP and 7-HC can inhibit fibrosis by inhibiting CCAAT/enhancer binding protein beta (C/EBPβ) expression in renal tubular cells. Normalization of lipid metabolism by HP and 7-HC further provided protection of mitochondrial structure integrity and inhibited the nuclear factor kappa-B (NF-κB) pathway. Long-term toxicity using beagle dogs proved the safety of HP after one-month administration. ConclusionCoumarin derivates from HP alleviate adriamycin-induced lipotoxicity and fibrosis in kidney through activating AMPK and inhibiting C/EBPβ.

Differences and Intersections in Renal Biopsy Findings in Patients with Asymptomatic Hyperuricemia and Gout

The aim of this study is to establish the association between asymptomatic hyperuricemia and gout with morphological and immunofluorescent changes in the renal biopsy. A total of 64 patients, 46 with asymptomatic hyperuricemia and 18 with gout were included in this retrospective study. Renal biopsy findings, clinical and laboratory data were analyzed by using medical documentation. We did not find a significant difference in the distribution of chronic renal failure between the two groups. In the gout group, the proportion of patients with nephrolithiasis was higher (p <0.001), and the presence of erythrocyturia was more common (p = 0.047). The percentage of damaged glomeruli (p = 0.249) and the distribution of mesangial proliferation (p = 0.536) was similar in the groups. The proportion of patients with interstitial fibrosis > 50$% was significantly higher in the gout group (p = 0.032), but no difference was observed in the distribution of tubular atrophy > 50% (p = 0.183). In subjects not receiving urate-lowering therapy, serum uric acid levels were comparable in the different stages of tubular atrophy and interstitial fibrosis. We found that in both asymptomatic hyperuricemia and gout, there is a deposition of immune deposits subepithelially, subendothelially, in the mesangium and in the vessel walls. In gout, the kidneys are affected to a much greater extent. We consider that not only the increased serum uric acid is important, but also monosodium urate crystals deposited in the renal interstitium causing a chronic inflammatory process followed by fibrosis. We suggest that the activation of the innate immune system by soluble uric acid and crystals with the subsequent development of a proinflammatory state in the body has led to the activation of complement and deposition of immune deposits in the kidneys.

Vancomycin nephrotoxicity: A comprehensive clinico-pathological study.

Vancomycin, a commonly prescribed antibiotic particularly in the setting of multi-drug resistant infections, is limited by its nephrotoxicity. Despite its common occurrence, much remains unknown on the clinicopathologic profile as well as the pathogenesis of vancomycin nephrotoxicity. Clinical studies included patients often with severe comorbidities and concomitant polypharmacy confounding the causal pathogenesis. Animal models cannot recapitulate this complex clinical situation. Kidney biopsy was not commonly performed. To address this limitation, we studied 36 patients who had renal biopsies for acute kidney injury (AKI) for suspicion of vancomycin nephrotoxicity. Detailed renal biopsy evaluation, meticulous evaluation of clinical profiles, and up-to-date follow-up allowed for a diagnostic categorization of vancomycin nephrotoxicity (VNT) in 25 patients and absence of vancomycin nephrotoxicity (NO-VNT) in 11 patients. For careful comparison of these two groups, we proceeded to compile a clinicopathologic and morphologic profiles characteristic for each group. Patients with VNT had a characteristic clinical profile including a common clinical background, a high serum trough level of vancomycin, a rapidly developed and severe acute kidney injury, and a recovery of renal function often shortly after discontinuation of vancomycin. This clinical course was correlated with characteristic renal biopsy findings including acute tubulointerstitial nephritis of allergic type, frequent granulomatous inflammation, concomitant and pronounced acute tubular necrosis of nephrotoxic type, and vancomycin casts, in the absence of significant tubular atrophy and interstitial fibrosis. This clinico-pathologic profile was different from that of patients with NO-VNT, highlighting its role in the diagnosis, management and pathogenetic exploration of vancomycin nephrotoxicity. Vancomycin nephrotoxicity has a distinctive morphologic and clinical profile, which should facilitate diagnosis, guide treatment and prognostication, and confer pathogenetic insights.

Characteristics and Outcomes of NELL1 Membranous Nephropathy in Lipoic Acid Users and Nonusers

Neural epidermal growth factor like 1 membranous nephropathy (NELL1 MN) is associated with various secondary etiologies. However, previous studies on the frequency of these associations and their impact on outcomes are limited. We report a large multiinstitutional series of patients with NELL1 MN with a focus on secondary associations, pathology findings, and their impact on outcome. We retrospectively reviewed clinicopathologic features of NELL1 MN from 3 institutions and analyzed clinical and histologic associations with outcome. Of 70 patients, 53% were male with a median age of 66 years; median proteinuria was 5.9 g/d. NELL1 MN was associated with lipoic acid (36%), heavy nonsteroidal antiinflammatory drug (NSAID) use (27%), autoimmune disease (23%), malignancy (10% recent, 23% any), mercury exposure (1%), and 11% had no known secondary association. At median follow-up of 11 months, 72% achieved complete or partial remission. Remission rate was 91% in patients with lipoic acid-associated NELL1 MN and≥6 months of follow-up. On multivariable analyses, patients with primary NELL1 MN (adjusted odds ratio [OR]: 19.7, P= 0.01) and increasing degree of tubular atrophy and interstitial fibrosis (IFTA) (adjusted OR 1.1, P= 0.01) were less likely to achieve any remission, whereas complete remission (CR) was associated with lipoic acid use (adjusted OR: 10.9, P= 0.04, 95% confidence interval [CI]: 1.2-100) and lesser degrees of IFTA (adjusted OR: 0.79, P= 0.16, 95% CI: 0.66-0.96). Our findings strengthen the association between lipoic acid and NELL1 MN. Furthermore, our findings suggest that discontinuation of lipoic acid without immunosuppression should be considered as the first-line treatment.

Keratin Expression in Podocytopathies, ANCA-Associated Vasculitis and IgA Nephropathy.

Keratins are the main components of the cell cytoskeleton of epithelial cells. Epithelial cells under stressful stimuli react by modifying their keratin expression pattern. Glomerular diseases are pathological conditions that may lead to loss of kidney function if not timely diagnosed and treated properly. This study aims to examine glomerular and tubular keratin expression in podocytopathies, ANCA-associated vasculitis, and IgA nephropathy and how this expression correlates to clinical outcomes. We included 45 patients with podocytopathies (minimal change disease and focal segmental glomerulosclerosis), ANCA-associated vasculitis, and IgA nephropathy, with or without crescentic lesions, and healthy controls. All tissues were assessed by photon microscopy and immunohistochemistry. Biopsy sections were examined for keratins 7, 8, 18, and 19 expression in the glomerular and tubulointerstitial areas separately. Moreover, we examined how keratin expression was correlated with long-term kidney function outcomes. All four studied keratins had significantly increased glomerular expression in patients with ANCA vasculitis compared to controls and MCD patients. Tubular expression of keratins 7, 8, and 19 was related to kidney outcome in all groups. Patients with crescents had higher expression of all keratins in both glomeruli and tubulointerstitium. The presence of tubular atrophy, interstitial fibrosis, mesangial hyperplasia, and interstitial inflammation did not affect keratin expression. Keratins, an abundant component of renal epithelial cells, have the potential to be featured as a biomarker for kidney function prognosis in patients with glomerular diseases.

Clinicopathologic Characteristics, Etiologies, and Outcome of Secondary Oxalate Nephropathy

ObjectiveTo report the clinicopathologic characteristics, prognostic indicators, prognosis, and transplant outcome of secondary oxalate nephropathy (ON). Patients and MethodsWe performed a retrospective analysis of 113 consecutive patients with secondary ON diagnosed at Mayo Clinic in Rochester, Minnesota, between January 1, 2001, and March 1, 2023. ResultsThe incidence of secondary ON among all native biopsies from Mayo Clinic patients over the study period (n=11,617) was 0.97%. ON was attributed to enteric hyperoxaluria in 60% of the 113 patients (68; most commonly Roux-en-Y gastric bypass), excessive ingestion of foods high in oxalate or oxalate precursors in 23% (26) (most commonly vitamin C), and idiopathic in 17% (19). Most patients presented with acute kidney injury (AKI) (particularly in the ingestion group) or AKI on chronic kidney disease, and 53% (60 of 113) were diabetic. Calcium oxalate crystals were accompanied by acute tubular injury, inflammation, and interstitial fibrosis and tubular atrophy. Concurrent pathologic conditions were present in 53% of the patients (60 of 113), most commonly diabetic nephropathy. After a median follow-up of 36 months, 27% of the patients (30 of 112) had kidney recovery, 19% (21 of 112) had persistent kidney dysfunction, 54% (61 of 112) had development of kidney failure, and 29% (32 of 112) died. The mean kidney survival was worse for patients with a concurrent pathologic lesion (30 months vs 96 months for those without a concurrent pathologic lesion; P<.001). Independent predictors of kidney failure were the degree of interstitial fibrosis and tubular atrophy and nadir estimated glomerular filtration rate but not the degree of crystal deposition. After a median follow-up of 58 months in 23 patients who received kidney transplant, 4 had graft loss (due to ON in 3). The 2-, 5-, and 10-year graft survivals were 90% (18 of 20), 79% (11 of 14), and 50% (6 of 12). ConclusionON is a rare cause of AKI or AKI on chronic kidney disease. Most patients have comorbid pathologic conditions, particularly diabetic nephropathy, which worsen the prognosis. Recurrence in the renal allograft and graft loss may occur if hyperoxaluria is not controlled.

Downregulating ANGPTL3 by miR-144-3p promoted TGF-β1-induced renal interstitial fibrosis via activating PI3K/AKT signaling pathway

Despite observations of decreased ANGPTL3 (angiopoietin-like protein 3) levels in tubular atrophy and renal interstitial fibrosis (RIF), its functional implications and regulatory mechanisms in RIF remain unclear. This investigation employed unilateral ureteral obstruction (UUO) mice as in vivo model and human proximal kidney tubuloepithelial HK-2 cells under TGF-β1 treatment as in vitro model to explore RIF. The RIF extent was evaluated using H & E staining and Masson's trichrome staining. There was a significant decrease in ANGPTL3 levels and an increase in miR-144-3p, accompanied by heightened expressions of α-SMA, p-PI3K, p-AKT, Collagen I, and Fibronectin in the UUO mice and HK-2 cells treated with TGF-β1. Enhancing ANGPTL3 expression or suppressing miR-144-3p mitigated TGF-β1-induced cellular apoptosis, inflammation, and PI3K/AKT signaling pathway activation, as evidenced by altered levels of α-SMA, Collagen I, Fibronectin, and associated signaling markers. Using a bioinformatics approach, a miR-144-3p binding site was discovered on the ANGPTL3 mRNA, and this finding was subsequently confirmed through luciferase reporter assay. In HK-2 cells stimulated with TGF-β1, the suppression of ANGPTL3 negated the effects of inhibiting miR-144-3p. Under comparable conditions, the use of LY294002, an inhibitor of the PI3K/AKT pathway, nullified the effects caused by the knockdown of ANGPTL3. Collectively, these findings indicate that miR-144-3p exacerbates RIF through PI3K/AKT pathway activation by targeting ANGPTL3, highlighting a novel potential therapeutic target for RIF management.

The Clinical and Pathological Effects of Serum C3 Level and Mesangial C3 Intensity in Patients with IgA Nephropathy.

To investigate the clinical and pathological effects of serum C3 level, mesangial C3 deposition intensity and blood lipid on IgA nephropathy. According to the deposition intensity of immunofluorescence (IF) complement C3 in mesangial region, a total of 151 patients were divided into: (1) negative group (65 cases), (2) weak positive group (51 cases), and (3) strong positive group (35 cases). According to the level of serum C3, the patients were divided into two groups: (1) 33 patients with decreased serum C3 (<85 mg/dL); (2) 118 patients with normal serum C3. The clinicopathological data of the patients were analyzed retrospectively according to the groups. (1) With the increase of C3 deposition in mesangial region, the mean value of serum C3 level decreased, and the difference was statistically significant (P=0.001). (2) Compared with the normal serum C3 group, the blood urea nitrogen (BUN), serum creatinine (Scr), and albumin (Alb) in the serum C3 decreased group were higher, and the differences were statistically significant (P < 0.05), while the fasting blood glucose (FBG), low-density lipoprotein (LDL), triglyceride and 24-hr urinary protein (24hUTP) were lower, which difference was statistically significant (P < 0.05). (3) Compared with negative group and weak positive group, BUN, uric acid (UA), and Scr were higher in the strong positive group with C3 deposition, while eGFR was lower, with statistical significance (P < 0.05). However, C3 deposition in the mesangial region was related to T and enhanced mesangial C3 deposition was associated with more severe tubular atrophy and/or interstitial fibrosis, with statistically significant differences (P=0.001). Patients with strong mesangial C3 deposition and elevated lipid levels had more severe tubule atrophy and/or interstitial fibrosis, as well as more severe pathological lesions, suggesting that activation of the complement system is involved in the pathogenesis of IgA nephropathy and increases the metabolic burden of the kidney.

Effects of Waterpipe Smoke Exposure on Experimentally Induced Chronic Kidney Disease in Mice.

Tobacco smoking is an independent risk factor in the onset of kidney disease. To date, there have been no reports on the influence of waterpipe smoke (WPS) in experimentally induced chronic kidney disease (CKD) models. We studied the effects and mechanisms of actions of WPS on a mouse model of adenine-induced CKD. Mice fed either a normal diet, or an adenine-added diet and were exposed to either air or WPS (30 min/day and 5 days/week) for four consecutive weeks. Plasma creatinine, urea and indoxyl sulfate increased and creatinine clearance decreased in adenine + WPS versus either WPS or adenine + saline groups. The urinary concentrations of kidney injury molecule-1 and adiponectin and the activities of neutrophil gelatinase-associated lipocalin and N-acetyl-β-D-glucosaminidase were augmented in adenine + WPS compared with either adenine + air or WPS groups. In the kidney tissue, several markers of oxidative stress and inflammation were higher in adenine + WPS than in either adenine + air or WPS groups. Compared with the controls, WPS inhalation in mice with CKD increased DNA damage, and urinary concentration of 8-hydroxy-2-deoxyguanosine. Furthermore, the expressions of nuclear factor κB (NF-κB) and mitogen-activated protein kinases (MAPKs) (ERK and p38) were elevated in the kidneys of adenine + WPS group, compared with the controls. Likewise, the kidneys of adenine + WPS group revealed more marked histological tubular injury, chronic inflammation and interstitial fibrosis. In conclusion, WPS inhalation aggravates kidney injury, oxidative stress, inflammation, DNA damage and fibrosis in mice with adenine-induced CKD, indicating that WPS exposure intensifies CKD. These effects were associated with a mechanism involving NF-κB, ERK and p38 activations.

Development and validation of a diagnostic nomogram to evaluate tubular atrophy/interstitial fibrosis of IgA nephropathy.

Background: IgA nephropathy (IgAN) is a cause of chronic kidney disease (CKD). Tubular atrophy/interstitial fibrosis is associated with IgAN prognosis. However, simple tools for predicting pathological lesions of IgAN remain limited. Our objective was to develop a tool for evaluating tubular atrophy/interstitial fibrosis in patients with IgAN. Methods: In this cross-sectional study, 410 biopsy-verified IgAN patients were included. The factors associated with the incident interstitial fibrosis or tubular atrophy in IgAN were confirmed by using logistic regression analysis. A nomogram was developed using logistic regression coefficients to evaluate tubular atrophy or interstitial fibrosis. Receiver operating characteristic curves (ROC) and calibration curves were used to determine the discriminative ability and predictive accuracy of the nomogram. Results: In this study, the IgAN patients with tubular atrophy or interstitial fibrosis were older and had a higher percentage of males, hypertension and urinary protein excretion (UPE), with high levels of serum cystatin C, serum creatinine, high-sensitivity C-reactive protein and serum C4. The eGFRcr-cys equation calculated using serum creatinine, cystatin C and UPE were considered independent influencing factors of tubular atrophy or interstitial fibrosis in patients with IgAN. Furthermore, the nomogram demonstrated good discrimination (AUC: 0.87, 95% CI 0.81 to 0.93) and calibration in the validation cohort. Conclusion: The eGFRcr-cys and UPE are associated with tubular atrophy or interstitial fibrosis in patients with IgAN. Diagnostic nomogram can predict tubular atrophy or interstitial fibrosis in IgAN.

Chronic kidney disease in a murine model of non-alcoholic steatohepatitis (NASH)

Clinical studies suggest that non-alcoholic steatohepatitis (NASH) is an independent risk factor for chronic kidney disease (CKD), but causality and mechanisms linking these two major diseases are lacking. To assess whether NASH can induce CKD, we have characterized kidney function, histological features, transcriptomic and lipidomic profiles in a well-validated murine NASH model. Mice with NASH progressively developed significant podocyte foot process effacement, proteinuria, glomerulosclerosis, tubular epithelial cell injury, lipid accumulation, and interstitial fibrosis. The progression of kidney fibrosis paralleled the severity of the histologic NASH-activity score. Significantly, we confirmed the causal link between NASH and CKD by orthotopic liver transplantation, which attenuated proteinuria, kidney dysfunction, and fibrosis compared with control sham operated mice. Transcriptomic analysis of mouse kidney cortices revealed differentially expressed genes that were highly enriched in mitochondrial dysfunction, lipid metabolic process, and insulin signaling pathways in NASH-induced CKD. Lipidomic analysis of kidney cortices further revealed that phospholipids and sphingolipids were the most significantly changed lipid species. Notably, we found similar kidney histological changes in human NASH and CKD. Thus, our results confirm a causative role of NASH in the development of CKD, reveal potential pathophysiologic mechanisms of NASH-induced kidney injury, and established a valuable model to study the pathogenesis of NASH-associated CKD. This is an important feature of fatty liver disease that has been largely overlooked but has clinical and prognostic importance.

Total glucosides of peony regulate toll-like receptor to inhibit inflammatory response in diabetic nephropathy

Diabetic nephropathy (DN) is a common chronic disease affecting people’s life. Total glucosides of peony (TGP) regulates TLR4/NF-κB activation. This study aims at investigating the underlying mechanism of TGP in DN treatment. A retrospective analysis of clinical data was conducted to observe periodic acid-silver metheramine (PASM) staining and detect the expression of TLR4 and VEGF in DN. Additionally, rats were injected with Streptozocin (STZ) (30–60 mg) according to the ratio of 45–65 mg/kg to establish DN model. 8 weeks later, rats of experimental group were intraperitoneally injected with TGP. Kidney was collected for HE staining to observe morphological changes. Fibronectin expression was detected by histochemistry and the level of TLR4/NF-κB pathway-related proteins and apoptosis were detected by Western blot. PASM staining revealed focal tubular atrophy and interstitial fibrosis in DN patients. The renal medulla gradually disappeared and infiltration increased in control group, while inflammatory cells decreased in experimental group. The expression of fibronectin, TLR4 and p-p65 was decreased after TGP treatment. TGP treatment significantly decreased fibronectin expression and TGP treatment-induced inhibition of NF-κB signaling enhanced apoptotic activation of HK-2 cells, which was partially reversed by TLR4 and NF-κB inhibitors. TGP can inhibit inflammatory response of DN via regulating TLR4/NF-κB.