IgA Nephropathy Group Research Articles

Pattern Recognition of Trace Element vs Heavy Elements in Patients with Membranous Nephropathy.

The objective of the present study was to investigate the role of trace elements and heavy elements in the pattern recognition in patients with membranous nephropathy. Elements such as V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Cd, Cs, Ba, Pb, and Hg were quantified by inductively coupled plasma mass spectrometry in blood and urine of 14 patients with membranous nephropathy, 14 patients with IgA nephropathy, and 13 normal controls. The blood levels of Cr, Co, Ni, Cu, Zn, Ga, As, Cd, and Ba and the urine levels of Co, Ni, Cu, and Zn in patients with membranous nephropathy were significantly lower than those in normal controls (P < 0.05), while the blood levels of Se, Pb, and Hg and the urine level of Hg were higher (P < 0.05). The blood levels of V, Cr, Co, Cu, As, Sr, Cd, and Ba and the urine levels of Sr and Ba in the patients with membranous nephropathy were significantly lower than those in the IgA nephropathy group (P < 0.05), while the blood and the urine levels of Pb and Hg were higher (P < 0.05). Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to analyze the results of elements. The results showed that Co, Zn, Hg, and Ba in the blood and Co and Ni in urine significantly contributed to the discriminant model of membranous nephropathy and normal controls; Sr in the blood and Pb and Sr in urine significantly contributed to the discriminant model of membranous nephropathy and IgA nephropathy.

Prognostic Value of Inflammation Scores and Hematological Indices in IgA and Membranous Nephropathies: An Exploratory Study.

Background and Objectives: Systemic-inflammation-based prognostic scores and hematological indices have shown value in predicting outcomes in various clinical settings. However, their effectiveness in predicting outcomes specifically for IgA nephropathy (IgAN) and membranous nephropathy (MN), the most common primary glomerular diseases diagnosed by kidney biopsy, has not been thoroughly investigated. Materials and Methods: We conducted a retrospective, observational study involving 334 adult patients with biopsy-proven IgAN (196 patients) and MN (138 patients) from January 2008 to December 2017 at a tertiary center. We assessed six prognostic scores [Glasgow prognostic score (GPS), modified GPS (mGPS), prognostic nutritional index (PNI), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-C-reactive protein ratio (LCRP)] and two hematological indices [red blood cell distribution width (RDW), platelet distribution width (PDW)] at diagnosis and examined their relationship with kidney and patient survival. Results: End-stage kidney disease (ESKD) occurred more frequently in the IgAN group compared to the MN group (37% vs. 12%, p = 0.001). The mean kidney survival time was 10.7 years in the IgAN cohort and 13.8 years in the MN cohort. After adjusting for eGFR and proteinuria, lower NLR and higher LCRP were significant risk factors for ESKD in IgAN. In the MN cohort, no systemic-inflammation-based scores or hematological indices were associated with kidney survival. There were 38 deaths (19%) in the IgAN group and 29 deaths (21%) in the MN group, showing no significant difference in mortality rates. The mean survival time was 13.4 years for the IgAN group and 12.7 years for the MN group. In the IgAN group, a lower PLR was associated with a higher mortality after adjusting for age, the Charlson comorbidity score, eGFR, and proteinuria. In patients with MN, higher NLR, PLR, and RDW were associated with increased mortality. Conclusions: NLR and LCRP are significant predictors of ESKD in IgAN, while PLR is linked to increased mortality. In MN, NLR, PLR, and RDW are predictors of mortality but not kidney survival. These findings underscore the need for disease-specific biomarkers and indicate that systemic inflammatory responses play varying roles in the progression and outcomes of these glomerular diseases. Future studies on larger cohorts are necessary to validate these markers.

Humoral immune responses primed by the alteration of gut microbiota were associated with galactose-deficient IgA1 production in IgA nephropathy.

Galactose-deficient IgA1 (GdIgA1) is critical in the formation of immunodeposits in IgA nephropathy (IgAN), whereas the origin of GdIgA1 is unknown. We focused on the immune response to fecal microbiota in patients with IgAN. By running 16S ribosomal RNA gene sequencing, we compared IgAN samples to the control samples from household-matched or non-related individuals. Levels of plasma GdIgA1 and poly-IgA complexes were measured, and candidate microbes that can either incite IgA-directed antibody response or degrade IgA through specific IgA protease activities were identified. The IgAN group showed a distinct composition of fecal microbiota as compared to healthy controls. Particularly, high abundance of Escherichia-Shigella was associated with the disease group based on analyses using receiver operating characteristic (area under curve, 0.837; 95% CI, 0.738-0.914), principle coordinates, and the linear discriminant analysis effect size algorithm (linear discriminant analysis score, 4.56; p < 0.001). Accordingly, the bacterial levels directly correlated with high titers of plasma GdIgA1(r = 0.36, p < 0.001), and patients had higher IgA1 against stx2(2.88 ± 0.46 IU/mL vs. 1.34 ± 0.35 IU/mL, p = 0.03), the main antigen of Escherichia-Shigella. Conversely, the healthy controls showed relatively higher abundance of the commensal bacteria that produce IgA-degrading proteases. Particularly, the abundance of some intestinal bacteria expressing IgA proteases showed an inverse correlation with the levels of plasma GdIgA1 in IgAN. Our data suggest that mucosal IgA production, including those of GdIgA1, is potentially linked to the humoral response to gut Escherichia-Shigella as one of the sources of plasma GdIgA1. Conversely, the IgA protease-producing microbiota in the gut are suppressed in patients with IgAN.

#1257 Complement system is overactivated in patients with IgA nephropathy after COVID-19

Abstract Background and Aims Since the coronavirus disease of 2019 (COVID-19) pandemic swept across the world, the flare of immune-mediated disease following SARS-CoV-2 infection has emerged rapidly. IgA nephropathy (IgAN), which has been confirmed as a complement mediated autoimmune disease, is also one of the common glomerulonephritis associated with COVID-19. Here, we aim to investigate the clinical and immunological characteristics of patients with IgAN after COVID-19. Method From December 2022 to April 2023, 33 patients with renal biopsy-proven IgAN (Group CoV) at Beijing Anzhen hospital who had experienced COVID-19 before renal biopsy were enrolled. Meanwhile, 44 patients with IgAN (Group non-CoV) diagnosed from December 2018 to April 2019 (the same period in the previous year, with no COVID-19) were enrolled as control. Plasma FHR-5, MBL, C5a, soluble C5b-9, serum Gd-IgA1 and IgA immune complex were detected by enzyme-linked immunosorbent assay. Glomerular staining for FHR-5, C3c, MAC and Gd-IgA1 were detected by immunofluorescence. SARS-CoV-2 nucleocapsid was detected by immunohistochemistry. Clinicopathological and immunological features between the two groups were analyzed. Results The median time between onset of COVID-19 symptoms and the time of renal biopsy was 12 (6, 18) weeks, ranging from 1 to 26 weeks. SARS-CoV-2 nucleocapsid antigen expression in the renal tubular epithelial cells were observed in 11/33 (33.3%) patients. Compared with Group non-CoV, the level of eGFR was significantly lower in Group CoV[67.30 (52.94, 96.43) ml/min per 1.73 m2 vs. 101.04 (74.35, 120.98) ml/min per 1.73 m2, p = 0.010]. Histologically, compared with Group non-CoV, Group CoV presented with more percentages of segmental glomerulosclerosis/adhesion (p = 0.003) and less percentages of mesangial hypercellularity (p = 0.017). The level of plasma level of C5a [16.45 (10.48, 22.07) ng/ml vs. 3.68 (2.70, 4.47) ng/ml], soluble C5b-9 [614.43 (481.66, 770.02) ng/ml vs. 358.08 (304.83, 471.77) ng/ml], FHR5 [4.01 (3.51, 4.48) ug/ml vs. 2.73 (2.25, 3.21) ug/ml]were all significantly higher in Group CoV compared with Group non-CoV, respectively (p &amp;lt; 0.001). Although the plasma level of MBL showed no difference in Group CoV and Group non-CoV, the proportion of high levels of MBL in Group CoV was higher than in Group non-CoV (p = 0.025). Compared with Group non-CoV, the intensity of glomerular MAC deposition was much stronger in Group CoV. There were no significant differences in serum levels of IgA, Gd-IgA1, IgA immune complex between two Groups. However, a greater intensity of Gd-IgA1 deposition in glomerular mesangial and capillary areas has been exhibited in Group CoV than those in Group non-CoV (p = 0.005). Conclusion For IgAN after COVID-19, mucosal immune responses to SARS-CoV-2 infection may result in the overactivation of systemic and renal local complement system, which is the first hit, and increased glomerular deposition of Gd-IgA1 is the second hit. We think that these two hits may lead to renal dysfunction and promote renal progression in IgAN patients. It is crucial to emphasize the necessity for long term follow-up in these patients of IgAN after COVID-19. Additionally, we propose that inhibitors targeting the mediators of complement activation might be a promising therapy for these IgAN patients after SARS-CoV-2 infection.

IgA nephropathy: gut microbiome regulates the production of hypoglycosilated IgA1 via the TLR4 signaling pathway.

Immunoglobulin A nephropathy (IgAN) is a major cause of primary glomerulonephritis characterized by mesangial deposits of galactose-deficient IgA1 (Gd-IgA1). Toll-like receptors (TLRs), particularly TLR4, are involved in the pathogenesis of IgAN. The role of gut microbiota on IgAN patients was recently investigated. However, whether gut microbial modifications of Gd-IgA1 through TLR4 play a role in IgAN remains unclear. We recruited subjects into four groups, including 48 patients with untreated IgAN, 22 treated IgAN patients (IgANIT), 22 primary membranous nephropathy and 31 healthy controls (HCs). Fecal samples were collected to analyze changes in gut microbiome. Gd-IgA1 levels, expression of TLR4, B-cell stimulators and intestinal barrier function were evaluated in all subjects. C57BL/6 mice were treated with a broad-spectrum antibiotic cocktail to deplete the gut microbiota and then gavaged with fecal microbiota transplanted from clinical subjects of every group. Gd-IgA1 and TLR4 pathway were detected in peripheral blood mononuclear cells (PBMCs) from IgAN and HCs co-incubated with lipopolysaccharide (LPS) and TLR4 inhibitor. Compared with the other three groups, different compositions and decreased diversity demonstrated gut dysbiosis in the untreated IgAN group, especially the enrichment of Escherichia-Shigella. Elevated Gd-IgA1 levels were found in untreated IgAN patients and correlated with gut dysbiosis, TLR4, B-cell stimulators, indexes of intestinal barrier damage and proinflammatory cytokines. In vivo, mice colonized with gut microbiota from IgAN and IgANIT patients mimicked the IgAN phenotype with the activation of TLR4/MyD88/nuclear factor-κB pathway and B-cell stimulators in the intestine, and had with enhanced proinflammatory cytokines. In vitro, LPS activated TLR4/MyD88/NF-κB pathway, B-cell stimulators and proinflammatory cytokines in PBMCs of IgAN patients. This process may induce the overproduction of Gd-IgA1, which was inhibited by TLR4 inhibitors. Our results illustrated that the gut-kidney axis is involved in the pathogenesis of IgAN. Gut dysbiosis could stimulate the overproduction of Gd-IgA1 via TLR4 signaling pathway production and B-cell stimulators.

Characteristics of renal pathology and coagulation function in IgA nephropathy and IgA vasculitis associated nephritis

BackgroundThe objective of this study is to investigate the clinical and pathological differences between patients with IgA nephropathy (IgAN) and IgA vasculitis associated nephritis (IgAVN).MethodsA total of 253 patients with IgAN and 71 patients with IgAVN were retrospectively included in the study, and clinical and laboratory data were collected and analysed.ResultsCompared with IgAVN group, months from onset to kidney biopsy were significantly prolonged in IgAN patients because of the lack of obvious symptoms such as rash, abdominal symptoms, and joint pain (13.5 ± 26.6 vs. 10.2 ± 31.6 months, P = 0.007), and the levels of serum creatinine (92.3 ± 94.7 vs. 68.9 ± 69.2 µmol/L, P = 0.015) was higher and eGFR (99.1 ± 35.2 vs. 123.4 ± 41.8 mL/min/1.73m2, P < 0.001) was lower in IgAN group. The pathological results revealed that patients with IgAN have a greater degree of chronic kidney injury compared to patients with IgAVN. In addition, the levels of plasma D-Dimers (1415.92 ± 1774.69 vs. 496.78 ± 711.91 ng/mL, P < 0.001) and fibrinogen degradation products (FDP) (3.92 ± 4.73 vs. 1.63 ± 2.46 µg/mL, P = 0.001) were significantly higher in IgAVN patients than in IgAN patients. The deposition of fibrinogen in the renal tissues was more severe and the cumulative partial remission rate was higher in patients with IgAVN as compared to those with IgAN (P = 0.001).ConclusionsIn comparison, IgAN patients had poorer renal function, whereas IgAVN patients had more severe coagulation abnormalities. These findings provide a basis for the differentiation of the two diseases at an early stage.

Hydroxychloroquine ameliorates immune functionality and intestinal flora disorders of IgA nephropathy by inhibition of C1GALT1/Cosmc pathway

Background Hydroxychloroquine (HCQ) has emerged as a potential and secure antiproteinuric agent in IgA nephropathy (IgAN). This study endeavored to explore the impact of HCQ on the immune functionality and intestinal flora disorders in IgAN rats, as well as to elucidate the underlying mechanisms through in vivo and in vitro experiments. Methods IgAN model was established in Sprague-Dawley rats through the administration of BSA, LPS, and CCl4, and the IgAN rats received a continuous 8-week treatment with HCQ. Moreover, the human glomerular mesangial cells (HMCs) were incubated with IgA1 to establish an in vitro cellular model of IgAN. At the end of experimental period, samples were collected for further analysis. Results HCQ ameliorated the elevated levels of 24hUTP, SCr, BUN, the number of urinary RBC, and the activation of inflammation-related proteins within the TLR4/NF-κB signaling pathway. In the IgAN rat group, there was a pronounced escalation in IgA deposition, mesangial matrix hyperplasia, and glomerular inflammatory cell infiltration, while the administration of HCQ effectively mitigated these pathological changes. In addition, the reduced production of CD4+CD25+Foxp3+ Treg in the IgAN group was effectively reversed by HCQ. Furthermore, HCQ has the capacity to restore the compromised state of the intestinal mucosal barrier induced by IgAN and mitigate the circumstances of intestinal permeability and disruption in the intestinal flora. Conclusion HCQ diminishes IgA aberrant glycosylation levels, ameliorates renal and intestinal histopathological damage, and attenuates intestinal flora disorders and immune dysfunction in IgAN rats by means of activating the C1GALT1/Cosmc pathway.

Molecular alterations of podocytes in primary focal segmental glomerulosclerosis and IgA nephropathy. (An exploratory study)

An evaluation of podocyte's molecular phenotype alterations in primary focal segmental glomerulosclerosis (pFSGS) and IgA nephropathy (IgAN). The exploratory study included 14 cases of morphologically confirmed pFSGS, 14 cases of IgAN, and 12 negative controls. The negative controls comprised samples of the unaltered renal cortex obtained during laparoscopic nephrectomy in patients with malignant neoplasms of the kidney and bladder and without proteinuria. A quantitative immunomorphological study of Wilms tumour protein (WT1) expression and mesenchymal markers of podocytes (desmin and vimentin) was conducted on all kidney samples. The co-expression of the aforementioned molecules was analysed using confocal microscopy. Cases of pFSGS exhibited nephrotic syndrome with proteinuria of 9.3 (3.1-14) g/24 and typical glomerular alterations in light microscopy and ultrastructural analysis. In the IgAN group, proteinuria was less severe (1.2 (0.7-1.6) g/24). The estimated glomerular filtration rate in pFSGS and IgAN was similar (pFSGS: 85 (53-103) ml/min/1.72 m², IgAN: 76 (52-87) ml/min/1.72 m²; p=0.40). In both pFSGS and IgAN, there was a reduction in WT1 expression in podocytes and an increase in vimentin expression when compared to negative controls. Compared to IgAN and controls, pFSGS exhibited a lower prevalence of glomerular WT1 expression and higher expression of desmin, which was predominantly localised in WT1-negative glomerular areas in confocal microscopy. In pFSGS, decreased nuclear expression of WT1 and increased expression of desmin were observed in the parietal epithelium of the glomerular capsule. Bidirectional alterations in the glomerular expression of WT1 and intermediate filament proteins are apparent in pFSGS and IgAN. These findings are suggestive for the genomic reprogramming of podocytes and the parietal epithelium of the glomerulus as part of the epithelial-mesenchymal transition, determining the structural and functional disorders of these cells, more prominent in pFSGS.

IgA vasculitis in adults, pediatrics and non-vasculitic IgA nephropathy, retrospective analysis from 2 centers.

Renal involvement represents the major long-term morbidity associated with IgA vasculitis (IgAV). Our aim was to evaluate clinical characteristics and long-term renal outcomes of IgAV in pediatrics and adults comparing to IgA nephropathy (IgAN). Our retrospective study included children and adults with IgAV and IgAN patients, admitted in a 13-year period (2007-2019) to rheumatology clinics and in hospital pediatric and internal medicine departments. We compared frequencies of clinical manifestations, laboratory findings, treatments, long-term outcomes at 1 year follow-up, including all-cause mortality and dialysis until the end of follow-up time. A total of 60 adult IgAV, 60 pediatric IgAV and 45 IgAN patients were evaluated. Adult IgAV patients were significantly older than IgAN patients (53.1 ± 17.4 years vs 45.1 ± 15.7 years respectively, P = .02) and had significantly higher rates of cardiovascular comorbidities. The risk and time to dialysis were similar among IgAN and adult IgAV groups. Yet, overall mortality at long term follow up was higher in IgAV adult group compared to IgAN. No dialysis or renal transplantation were reported in pediatric IgAV patients. IgAV and IgAN adult patients were comparable regarding risk of end stage renal disease. Of note, high mortality rates were observed among adult IgAV group.

Serum sulfatide level is associated with severe systemic vasculitis with kidney involvement.

Sulfatides are a type of sulfated glycosphingolipid that are secreted with lipoproteins into the serum. These molecules are involved in the inflammatory pathway of vessels in addition to coagulation and platelet aggregation. Previous studies have proposed that sulfatides play a pivotal role in regulating inflammation-related disorders. Systemic vasculitis (SV) diseases are generally caused by autoimmune diseases and often involve kidney vasculitis, which may lead to rapidly progressive kidney dysfunction and end-stage kidney disease. Our earlier pilot study revealed that the level of serum sulfatides (SSs) was significantly decreased in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV), a representative disease-causing SV with kidney involvement (SVKI), especially in patients exhibiting active crescentic findings on kidney biopsy. To further explore the clinical significance of an association between SS and SVKI, we analyzed and compared the SS level of patients with various SVKI diseases in this retrospective cohort study. Among patients admitted to our hospital between 2008 and 2021, we ultimately enrolled 26 patients with IgA vasculitis (IgAV), 62 patients with AAV, and 10 patients with anti-glomerular basement membrane disease (GBM) as examples of SVKI diseases, as well as 50 patients with IgA nephropathy (IgAN) and 23 donors for living kidney transplantation as controls. The mean ± standard deviation SS level in the donor, IgAN, IgAV, AAV, and GBM groups was 8.26 ± 1.72, 8.01 ± 2.21, 6.01 ± 1.73, 5.37 ± 1.97, and 2.73 ± 0.99 nmol/mL, respectively. Analysis of patients in the SVKI disease group showed that those with the crescentic class kidney biopsy finding exhibited a significantly lower SS level than did those with other class biopsy features. Additionally, the SS level had a higher detection ability for SVKI patients with crescentic class kidney biopsy findings (area under the receiver operating characteristic curve 0.90, 95% confidence interval 0.82-0.99) than did several other predictor candidates. Our results indicate that the SS level is decreased in more severe SVKI diseases and may be associated with active glomerular lesions in SVKI kidney biopsy samples.

Serum levels of sonic hedgehog in patients with IgA nephropathy are closely associated with intrarenal arteriolar lesions

BackgroundIntrarenal arteriolar disease is a major risk factor for poor prognosis in immunoglobulin A nephropathy (IgAN). The morphologic factor sonic hedgehog (SHH) plays an important role in a variety of vascular diseases, so it may be directly or indirectly involved in the process of renal arteriolar disease. The purpose of this study was to investigate the correlation between serum SHH levels and renal arteriole disease in patients with IgAN. MethodsSubjects with primary IgAN diagnosed by renal biopsy performed between October 2018 and August 2019 at the First Medical Center of the Chinese PLA General Hospital were recruited. Blood specimens were collected from the patients within 1 week before renal biopsy after they signed an informed consent form, and healthy controls were recruited for blood specimen collection during the same period. The concentration of serum SHH was measured by enzyme-linked immunosorbent assay in this population. ResultsSerum SHH levels were significantly lower in the IgAN group than in the control group. 41 of the 94 subjects diagnosed with IgAN had severe renal arteriolosclerosis and, compared to their less severely affected counterparts, were older, more hypertensive, and characterized by lower levels of SHH, higher levels of tubular atrophy/interstitial fibrosis and a higher Lee's classification. Serum SHH concentration was found to be an independent predictor of severe intrarenal arteriolosclerosis in IgAN subjects after correction using multivariate analysis. ConclusionIn this study, serum SHH levels were found to be significantly lower in patients with IgAN than in healthy subjects. Serum SHH may serve as a noninvasive biomarker of intrarenal arteriolosclerosis in patients with IgAN.

Porphyromonas gingivalis infection in the oral cavity is associated with elevated galactose-deficient IgA1 and increased nephritis severity in IgA nephropathy.

The relationship between the major periodontal bacteria, Porphyromonas gingivalis, and the pathogenesis of IgA nephropathy (IgAN)-particularly with respect to galactose-deficient IgA1 (Gd-IgA1)-has not been fully elucidated. Saliva samples from 30 IgAN patients and 44 patients with chronic kidney disease (CKD) were subjected to analysis of P. gingivalis status via polymerase chain reaction using a set of P. gingivalis-specific primers. The associations between P. gingivalis presence and clinical parameters, including plasma Gd-IgA1, were analyzed in each group. Compared with the CKD group, the IgAN group demonstrated significantly higher plasma Gd-IgA1 levels (p < 0.05). Compared with the P. gingivalis-negative subgroup, the P. gingivalis-positive subgroup exhibited significantly higher plasma Gd-IgA1 levels in both IgAN and CKD patients (p < 0.05). Additionally, among IgAN patients, the P. gingivalis-positive subgroup displayed significantly higher plasma Gd-IgA1 and urine protein levels, compared with the P. gingivalis-negative subgroup (p < 0.05). With respect to renal biopsy findings, the frequencies of segmental glomerulosclerosis and tubular atrophy/interstitial fibrosis were significantly greater in the P. gingivalis-positive subgroup than in the P. gingivalis-negative subgroup, according to the Oxford classification of IgAN (p < 0.05). Our findings suggest an association between the presence of P. gingivalis in the oral cavity and the pathogenesis of IgAN, mediated by increased levels of Gd-IgA1.

Detection of N‑glycoprotein associated with IgA nephropathy in urine as a potential diagnostic biomarker using glycosylated proteomic analysis.

The aim of the present study was to elucidate the potential diagnostic value of urinary N-glycoprotein in patients with IgA nephropathy (IgAN) using mass spectrometry (MS). All procedures were performed between June 2021 and June 2023 at Guangan People's Hospital (Guangan, China). Fresh mid-morning fasting midstream urine samples were collected from a total of 30 patients with IgAN and 30 sex- and age-matched healthy volunteers. Data acquired from 6 participants are available through ProteomeXchange with the identifier PXD041151. By comparison between the IgAN group (n=3) and healthy controls (n=3) and selection criteria of P<0.05 and |log fold-change|>2, a total of 11 upregulated and 22 downregulated glycoproteins in patients with IgAN were identified. The results of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses suggested that glycoproteins are involved in various functions, such as the regulation of cell growth, cell adhesion, cellular component organization and protein binding, as well as multiple pathways, including p53, Notch and mTOR signaling pathways. The urine levels of afamin were further measured by ELISA in a validation cohort to assess the diagnostic performance of the single indicator model. In conclusion, MS-based proteomics of urinary glycoproteins may be an alternative option for diagnosing patients with IgAN. Biomarkers of IgAN may include, but are not limited to, CCL25, PD-L1, HLA-DRB1, IL7RD and WDR82. In addition, the levels of urinary AFM indicators are of diagnostic value for IgAN.

Role of metabolomic profile as a potential marker to discriminate membranous nephropathy from IgA nephropathy.

Membranous nephropathy (MN) and IgA nephropathy (IgAN) are the most common primary glomerulopathies worldwide. The systemic metabolic changes in the progression of MN and IgAN are not fully understood. A total of 87 and 70 patients with MN and IgAN, respectively, and 30 healthy controls were enrolled in this study. Untargeted metabolomics was performed to explore the differential metabolites and metabolic pathways in the early stage of MN and IgAN. To judge the diagnostic ability of biomarkers, receiver operating characteristic curve analysis (ROC) were performed. Principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) suggested that patients with MN and IgAN showed an obvious separation trend from the healthy controls. In addition, 155 and 148 metabolites were identified to be significantly altered in the MN and IgAN groups, respectively. Of these, 70 metabolites were markedly altered in both disease groups; six metabolites, including L-tryptophan, L-kynurenine, gamma-aminobutyric acid (GABA), indoleacetaldehyde, 5-hydroxyindoleacetylglycine, and N-alpha-acetyllysine, showed theopposite tendency. The most affected metabolic pathways included the amino acid metabolic pathways, citrate cycle, pantothenate and CoA biosynthesis, and hormone signaling pathways. Substantial metabolic disorders occurred during the progression of MN and IgAN. L-tryptophan, L-kynurenine, GABA, indoleacetaldehyde, 5-hydroxyindoleacetylglycine, and N-alpha-acetyllysine may show potential as biomarkers for the identification of MN and IgAN.

#6041 THE IMMUNE EFFECTS OF SARS-COV-2 INFECTION AND BNT162B2 VACCINATION IN CKD PATIENTS AND TRANSPLANT RECIPIENTS

Abstract Background and Aims The use of vaccination against severe acute respiratory syndrome coronavirus (SARS-CoV-2) significantly limited the spread of the coronavirus disease 2019 (COVID-19) pandemic. However, it was reported that after 6 months of vaccination (including the BNT162b2 vaccine) immunity decreases in general population. The results for chronic kidney disease (CKD) patients and solid-organ transplant (SOT) recipients appeared similar. Therefore, it was proposed to use an immune booster with the next, third or fourth vaccination dose to prolong immunity. We aimed to find the most effective immunization schedules in CKD patients in comparison to kidney (KTRs) and liver transplant recipients (LTRs). Method We retrospectively analyzed the data of randomly selected 40 patients with IgA nephropathy (IgAN) as representatives of the CKD group and 78 SOT recipients (37 KTRs and 41 LTRs). They received two or three 30 μg doses of BNT162b2 vaccine. The follow up was performed in five time points (TP1-5): 4-6 weeks after the 1st dose (TP1), 4-8 weeks after 2nd dose (TP2), 9-20 weeks after 2nd dose (TP3), 21-32 weeks after 2nd dose and 1-12 weeks after 3rd dose (TP4), 33-48 weeks after 2nd dose, at the same time 4-20 weeks after 3rd dose (TP5). We assessed the anti-SARS-CoV-2 spike 1 protein IgG antibody (anti-S1 Ab) titer as well as graft function, COVID-19 history and patients’ clinical condition. Results We found Ab titer in IgAN group higher than in SOT patients (p = 0.05). LTRs achieved higher values than KTRs. 55 patients received 3 doses of vaccination. The protective level after the 3rd dose was not observed only in 8.4% at TP4 and 5% at TP5. We demonstrated the advantage in Ab levels of a 2 doses vaccination scheme with and without COVID-19 history over a 3 doses in a group of patients with no COVID-19 history in TP 1-4 (p = &amp;lt;0,001 - 0,005, respectively, Table1). Subjects in 2 doses schedule had a longer time to infection from the last dose compared to the 3 doses schedule (31.5-39 vs. 9 weeks, MD). No deterioration of renal or graft function was noted and no rejection episodes were diagnosed. Conclusion Immunocompromised patients are non-homogeneous with respect to the vaccine response immunity. Therefore, the approach to the vaccination schedule should be individualized based on measurements of vaccination response and medical history including COVID-19 history. Combined post-infectious and post-vaccination immunization appears to be the most effective in producing anti-SARS-CoV-2 responses.

Pregnancy Complications and Impact on Kidney Allograft After Kidney Transplantation in IgA Nephropathy.

Pregnancy in kidney transplantation (KT) recipients has been challenging because of the high risk of maternal, fetal, and renal complications. Although patients with immunoglobulin A nephropathy (IgAN)-chronic kidney disease (CKD) are at a high risk for hypertension in pregnancy (HIP), the maternal risk in KT recipients with IgAN as the etiology remains unclear. We retrospectively reviewed the medical records of pregnant KT recipients who delivered at our hospital. The incidence of maternal and fetal complications and the impact on kidney allografts between the group with IgAN as the primary kidney disease and the group with other primary diseases were compared. The analysis included 73 pregnancies in 64KT recipients. The IgAN group had a higher incidence of HIP than the non-IgAN group (69% vs. 40%, p = 0.02). IgAN as primary kidney disease and interval from transplantation to conception were associated with HIP (OR 3.33 [1.11-9.92], p = 0.03, OR 0.83 [0.72-0.96], p < 0.01, respectively). The 20-year graft survival or prevention of CKD stage 5 in group with IgAN was lower than that in the group with other primary disease (p < 0.01). KT recipients should be informed of the risk of HIP and possibility of long-term worsening of postpartum renal function.

In situ assessment of Mindin as a biomarker of podocyte lesions in diabetic nephropathy.

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease and end-stage renal failure worldwide. Several mechanisms are involved in the pathogenesis of this disease, which culminate in morphological changes such as podocyte injury. Despite the complex diagnosis and pathogenesis, limited attempts have been made to establish new biomarkers for DN. The higher concentration of Mindin protein in the urine of patients with type 2 diabetes mellitus suggests that it plays a role in DN. Therefore, this study investigated whether in situ protein expression of Mindin can be considered a potential DN biomarker. Fifty renal biopsies from patients diagnosed with DN, 57 with nondiabetic glomerular diseases, including 17 with focal segmental glomerulosclerosis (FSGS), 14 with minimal lesion disease (MLD) and 27 with immunoglobulin A nephropathy (IgAN), and 23 adult kidney samples from autopsies (control group) were evaluated for Mindin expression by immunohistochemistry. Podocyte density was inferred by Wilms' tumor 1 (WT1) immunostaining, while foot process effacement was assessed by transmission electron microscopy. Receiver operative characteristic (ROC) analysis was performed to determine the biomarker sensitivity/specificity. Low podocyte density and increased Mindin expression were observed in all cases of DN, regardless of their class. In the DN group, Mindin expression was significantly higher than that in the FSGS, MCD, IgAN and control groups. Higher Mindin expression was significantly positively correlated with foot process effacement only in class III DN cases. Furthermore, Mindin protein presented high specificity in the biopsies of patients with DN (p < 0.0001). Our data suggest that Mindin may play a role in DN pathogenesis and is a promising biomarker of podocyte lesions.

Significance of Mannan Binding Lectin-Associated Serine Protease 2 in Urinary Extracellular Vesicles in IgA Nephropathy.

Immunoglobulin A (IgA) nephropathy (IgAN) is a common chronic glomerulonephritis and the main cause of end-stage renal diseases. Recent evidence suggests that mannan binding lectin associated serine proteases 2 (MASP2) is related to IgAN; therefore, we investigated the expression and significance of MASP2 in serum and urinary extracellular vesicles (UEVs) in patients with IgAN. Thirty-eight patients with IgAN and 17 healthy controls were enrolled in this study. UEVs were extracted by ultracentrifugation. The separation by ultra-high-speed centrifuge was verified by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Candidate internal references (TSG101, CD9, flotillin, β-actin and GAPDH) were identified by western blotting in the control group, and the expression of MASP2 in the UEVs was compared. The levels of MASP2 in the serum and UEVs in the IgAN and control groups were determined by enzyme-linked immunosorbent assay (ELISA). TEM and NTA results demonstrated that UEVs were successfully extracted. Western blotting results confirmed that TSG101 was suitable as an internal reference for this study. Compared with the control group, the IgAN group showed positive expression of MASP2. MASP2 levels in the UEVs, determined by ELISA, showed significant differences between IgAN and control groups, which were significantly positively correlated with the level of urinary microalbumin. The level of MASP2 in UEVs was related to IgAN and shows promise as a biomarker for evaluating the severity of renal injury and prognosis of IgAN, thereby helping to elucidate the role of MASP2 in the mannan-binding lectin pathway.

Metagenomics-based systematic analysis reveals that gut microbiota Gd-IgA1-associated enzymes may play a key role in IgA nephropathy.

Background: IgA nephropathy (IgAN) is the most common type of glomerulonephritis in Asia. Its pathogenesis involves higher expression of galactose-deficient IgA1 (Gd-IgA1) and dysregulated intestinal mucosal immunity. The objective of this study was to explore whether specific gut microbiota and associated enzymes affect Gd-IgA1 in IgAN. Methods: This study carried out shotgun metagenomic sequencing with Illumina on fecal samples collected from 20 IgAN patients (IgAN group) and 20 healthy controls (HCs group) who were recruited from January 2016 to December 2018 at the Second Clinical College of Guangzhou University of Chinese Medicine. Differences analysis in gut microbiota was performed to determine the overall microbiota composition, the representative enterotypes, and the microbiota abundance. Correlations between gut microbiota and clinical indicators were assessed by Spearman’s analysis. Moreover, the functional prediction of microbial communities and the quantitative calculation of enzymes encoded by microbiome were performed using the MetaCyc pathway and the bioBakery three platform, respectively. Results: Bacteroides plebeius and Bacteroides vulgatus levels were higher, while Prevotella copri and Alistipes putredinis levels were lower in the IgAN group compared to HCs group. Enterotype I characterized by Bacteroides was closely related to the IgAN patients. Moreover, Bacteroides fragilis, Flavonifractor plautii and Ruminococcus gnavus were characteristic bacteria enriched in IgAN patients. Spearman’s correlation analysis found that Eggerthella lenta and Ruminococcus bromii were positively correlated with urine protein-creatinine ratio, while Ruminococcus gnavus showed a direct association with red blood cells in urine, and Bacteroides vulgatus and Ruminococcus gnavus were positively correlated with eGFR. These results indicated that intestinal dysbacteriosis occurred in IgAN patients and was associated with clinical and biochemical features. In addition, MetaCyc pathway analysis predicted microbiota-related metabolic pathways, including the biosynthesis of amino acids and glycans, were associated with the IgAN group. Microbial enzymes analysis highlighted that Gd-IgA1-associated α-galactosidase and α-N-acetyl-galactosaminidase secreted by Flavonifractor plautii were enriched in IgAN patients. Conclusion: These findings suggested that α-galactosidase and α-N-acetyl-galactosaminidase secreted by Flavonifractor plautii might be related to the production of Gd-IgA1, indicating that enzymes originated from abnormal intestinal microbiota may contribute to the production of Gd-IgA1 and play an important role in the pathogenesis of IgAN.

Clinical Significance of IgG4 Level in Predicting the Activity and Outcome of Phospholipase A2 Receptor-associated Membranous Nephropathy

Objective To investigate the feasibility of IgG4 as a biomarker of the activity and outcome of phospholipase A2 receptor (PLA2R)-associated membranous nephropathy (PLA2R-MN). Methods Serum and urine samples were collected from 56 patients with PLA2R-MN,13 patients with secondary membranous nephropathy (SMN),and 10 patients with primary IgA nephropathy (IgAN) when kidney biopsy was performed in the Department of Nephrology,Hangzhou Hospital of Traditional Chinese Medicine from April 2017 to January 2018.Sandwich enzyme-linked immunosorbent assay was employed to measure the serum and urinary IgG4 levels. Results The PLA2R-MN group had higher median serum IgG4/IgG ratio than the SMN group (P=0.009) and the IgAN group (P<0.001) and higher median urinary IgG4/creatinine ratio than the SMN group (P=0.008).In the patients with PLA2R-MN,the median serum IgG4/IgG ratio and urinary IgG4/creatinine ratio were significantly higher in the renal insufficiency group than in the normal renal function group (P=0.049,P=0.015).Moreover,the median serum IgG4/IgG ratio was higher in those with a serum albumin level<30 g/L than in those with a serum albumin level ≥30 g/L (P=0.005).Fifty-three patients with PLA2R-MN were followed up for at least 1 year,and the serum IgG4/IgG ratios of the patients in remission were lower than those of the patients without remission (P=0.005).The median serum IgG4/IgG ratio of 23 patients in remission decreased from 5.82% (4.54%,10.20%)(at initial enrollment) to 2.91% (2.11%,5.37%)(after 1-year follow up) in remission patients (P<0.001).The receiver operating characteristic curve showed that the patients with a serum IgG4/IgG ratio<10.24% had a higher possibility of remission (P=0.005). Conclusion Serum and urinary IgG4 levels may be an indicator of the activity in PLA2R-MN patients and thus may be a predictive biomarker of the outcomes.