The transcription factor HMGB2 indirectly regulates APRIL expression and Gd-IgA1 production in patients with IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Proliferation-inducing ligand (APRIL) was identified as an important cause of glycosylation deficiency of IgA1 (Gd-IgA1), which can 'trigger' IgAN. Our previous study indicated that high migration group protein B2 (HMGB2) in peripheral blood mononuclear cells from patients with IgAN was associated with disease severity, but the underlying mechanism remains unclear.

MATERIALS AND METHODS

The location of HMGB2 was identified by immunofluorescence. qRT-PCR and Western blotting were used to measure HMGB2, HMGA1, and APRIL expression. Gd-IgA1 levels were detected by enzyme-linked immunosorbent assay (ELISA). In addition, we used DNA pull-down, protein profiling, and transcription factor prediction software to identify proteins bound to the promoter region of the APRIL gene. RNA interference and coimmunoprecipitation (Co-IP) were used to verify the relationships among HMGB2, high mobility group AT-hook protein 1 (HMGA1), and APRIL.

RESULTS

HMGB2 expression was greater in IgAN patients than in HCs and was positively associated with APRIL expression in B cells. DNA pull-down and protein profiling revealed that HMGB2 and HMGA1 bound to the promoter region of the APRIL gene. The expression levels of HMGA1, APRIL, and Gd-IgA1 were downregulated after HMGB2 knockdown. Co-IP indicated that HMGB2 binds to HMGA1. The Gd-IgA1 concentration in the supernatant was reduced after HMGA1 knockdown. HMGA1 binding sites were predicted in the promoter region of the APRIL gene.

CONCLUSION

HMGB2 expression is greater in IgAN patients than in healthy controls; it promotes APRIL expression by interacting with HMGA1, thereby inducing Gd-IgA1 overexpression and leading to IgAN.

Development of a Conceptual Model for the Patient Experience of Immunoglobulin A Nephropathy (IgAN): A Qualitative Literature Review

INTRODUCTION

Immunoglobulin A nephropathy (IgAN) is a kidney disorder that can lead to progressive kidney disease. Currently, there lacks a comprehensive overview of the symptoms and impacts experienced by those living with IgAN that would help inform the selection or development of fit-for-purpose clinical outcome assessments (COA) to be used in clinical trials. The aim of this study was to develop a conceptual model of the adult and pediatric patient experience of IgAN, including disease signs and symptoms, treatment side effects, and impact on functioning and well-being.

METHODS

This study comprised a systematic review and thematic analysis of qualitative studies with adults and children diagnosed with IgAN. Data sources were identified through an electronic database search of journal articles (MEDLINE, Embase, PsycINFO; June 2021), hand-searching of conference proceedings, patient advocacy group websites, and gray literature. Non-English articles were excluded. Identified data (patient/caregiver quotes, author summaries, and interpretations of patient experiences) were extracted from articles. Extracted data were qualitatively analyzed, aided by ATLAS.ti v7. Codes were applied to data; concepts (i.e., symptoms) were identified, named, and refined. A conceptual model was developed by grouping related concepts into domains.

RESULTS

In total, five sources were identified for analysis: two journal articles, two online anthologies of patient stories, and one patient organization-sponsored "Voice of the Patient" meeting report. Conceptual model symptom domains included swelling/puffiness (edema), pain/aches/discomfort, fatigue, weight gain, sleep problems, urinary problems, and gastrointestinal problems. Impact domains included emotional/psychological well-being, physical functioning/activities of daily living, social functioning, work/school, and relationships.

CONCLUSIONS

Secondary analysis of published qualitative literature permitted development of a novel conceptual model depicting the patient experience of IgAN; however, its depth is limited by a lack of available literature. Further qualitative research is recommended to refine and/or confirm the concepts and domains, determine any relationships between them, and explore the outcomes that are most meaningful to patients. The refined model will provide a useful tool to inform the selection, development, and/or amendment of COAs for use in future IgAN clinical trials.

[Automatic classification of immune-mediated glomerular diseases based on multi-modal multi-instance learning]

OBJECTIVE

To develop a multi-modal deep learning method for automatic classification of immune-mediated glomerular diseases based on images of optical microscopy (OM), immunofluorescence microscopy (IM), and transmission electron microscopy (TEM).

METHODS

We retrospectively collected the pathological images from 273 patients and constructed a multi-modal multi- instance model for classification of 3 immune-mediated glomerular diseases, namely immunoglobulin A nephropathy (IgAN), membranous nephropathy (MN), and lupus nephritis (LN). This model adopts an instance-level multi-instance learning (I-MIL) method to select the TEM images for multi-modal feature fusion with the OM images and IM images of the same patient. By comparing this model with unimodal and bimodal models, we explored different combinations of the 3 modalities and the optimal methods for modal feature fusion.

RESULTS

The multi-modal multi-instance model combining OM, IM, and TEM images had a disease classification accuracy of (88.34±2.12)%, superior to that of the optimal unimodal model [(87.08±4.25)%] and that of the optimal bimodal model [(87.92±3.06)%].

CONCLUSION

This multi- modal multi- instance model based on OM, IM, and TEM images can achieve automatic classification of immune-mediated glomerular diseases with a good classification accuracy.

Renal tubular estrogen ß receptors are expressed at high levels in small vessel vasculitis and are primarily localized in the distal tubule

This study investigated the possible roles of renal estrogen receptors (ER) in glomerulonephritis associated with small vessel vasculitis. The relationships of ERs were investigated in antineutrophilic cytoplasmic antibody (ANCA)-associated glomerulonephritis and immunoglobulin A (IgA) nephropathy groups, which are small vessel vasculitis subtypes with two different glomerulonephritis development pathophysiologies. The design of this study was prepared as a retrospective cohort study. The study included 42 patients with ANCA-associated vasculitis and 18 with IgA nephropathy in the small vessel vasculitis group. For the control group, intact renal tissues of 28 patients who underwent nephrectomy due to renal cell carcinoma were used. Renal biopsy samples of the groups were stained with ER beta (ß) and ER alpha (α). Tubular ER ß expression score (TERßES) median values were found to be significantly higher in ANCA- associated vasculitis (B = 0.724, OR [95%CI]: 2.064 [1.141-3.731], p = .016) and IgA nephropathy (B = 0.898, OR [95%CI]: 2.454 [1.307-4.609], p = .005) than in intact kidney tissue. It was determined that tubular ERß was most frequently localized in the distal tubule at 57.9% and the second most common in the proximal tubule at 20.4%. The expression of tubular ERß is increased in glomerulonephritis due to small vessel vasculitis. Tubular ERßs are most commonly localized in the distal tubule. Further studies are needed to understand the physiological and pathophysiological effects of altered renal ER levels in small vessel vasculitis.

Utility of C4d Immunohistochemistry as an Adjunct Stain in Diagnostic Renal Pathology of Glomerular Diseases

C4d is a byproduct of the activation of the classic and lectin complement pathways. Being routinely used as a marker for antibody-mediated rejection, the significance of C4d in native kidney disease is currently being widely studied. We evaluated glomerular and extraglomerular C4d staining in 82 biopsies of proliferative and nonproliferative glomerulonephritis diagnosed in our institution. The staining pattern of C4d was tabulated in various glomerular diseases. All biopsies of membranous nephropathy including membranous lupus nephritis (Class V) and immune complex-mediated membranoproliferative glomerulonephritis (MPGN) consistently showed C4d deposits along glomerular basement membrane mirroring the location of immunoglobulin and complement in these conditions. Conversely, other glomerular diseases like IgA nephropathy, postinfectious glomerulonephritis, focal segmental glomerulosclerosis, minimal change disease, and diabetic nephropathy showed variable mesangial and capillary wall C4d deposits. To summarize, the consistent pattern of C4d staining in membranous nephropathy (primary and secondary)and immune complex-mediated MPGN can be used as a valuable adjunct tool in establishing the diagnosis, especially when immunofluorescence findings are limited by inadequate sampling.C4d reactivity in other glomerular diseases are variable and may not aid as a diagnostic tool in renal biopsy evaluation.

The effects of apoptosis inhibitor of macrophage in kidney diseases

Kidney disease is a progressive and irreversible condition in which immunity is a contributing factor that endangers human health. It is widely acknowledged that macrophages play a significant role in developing and causing numerous kidney diseases. The increasing focus on the mechanism by which macrophages express apoptosis inhibitor of macrophages (AIM) in renal diseases has been observed. AIM is an apoptosis inhibitor that stops different things that cause apoptosis from working. This keeps AIM-bound cell types alive. Notably, the maintenance of immune cell viability regulates immunity. As our investigation progressed, we concluded that AIM has two sides when it comes to renal diseases. AIM can modulate renal phagocytosis, expedite the elimination of renal tubular cell fragments, and mitigate tissue injury. AIM can additionally exacerbate the development of renal fibrosis and kidney disease by prolonging inflammation. IgA nephropathy (IgAN) may also worsen faster if more protein is in the urine. This is because IgA and immunoglobulin M are found together and expressed. In the review, we provide a comprehensive overview of prior research and concentrate on the impacts of AIM on diverse subcategories of nephropathies. We discovered that AIM is closely associated with renal diseases by playing a positive or negative role in the onset, progression, or cure of kidney disease. AIM is thus a potentially effective therapeutic target for kidney diseases.

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

Objective

To investigate the clinical and pathological effects of serum C3 level, mesangial C3 deposition intensity and blood lipid on IgA nephropathy.

Methods

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.

Results

(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).

Conclusion

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.

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

BACKGROUND

Intrarenal 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.

METHODS

Subjects 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.

RESULTS

Serum 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.

CONCLUSION

In 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.

Bibliometric analysis of mucosal immunity in IgA nephropathy from 1990 to 2022

OBJECTIVE

The study aimed to conduct a bibliometric analysis of mucosal immunity in IgA nephropathy (IgAN) and indicate its current status, hot sopts, and direction of future studies.

METHODS

The literature data was collected from the Web of Science Core Collection. CiteSpace 6.1.R3 was employed to conduct a visualization bibliometric analysis of mucosal immunity in IgA nephropathy, including authors, countries, journals, keywords, organizations, references, the bursts of keywords and references, and the timeline of keyword clusters and reference clusters.

RESULTS

A total of 315 publications from 1990 to 2022 were included. The number of articles in this field has increased in recent years. Suzuki H, Coppo R, and Feehally J took the first place parallelly with 18 articles. Japan contributes the most articles, accounting for 27.3% of all the publications. The institutions with the most publications were Juntendo University and University of Alabama Birmingham. 453 keywords were concluded in the analysis, which mainly focus on the mucosal pathogenesis and therapy of the IgAN. The top five co-cited reference cluster are "aberrantly glycosylated IgA," "corticosteroids," "animal models," "o-glycosylationm" and "microRNA-630." The most recently burst of keyword is "tonsillectomy" and "gut."

CONCLUSION

This was the first bibliometric analysis to systematically analyze the mucosal immunity in IgAN, which obtained the current status and indicated the future research hotspots and development trends. The gut microbiota and the related therapy-targeted mucosal immunity might be the future research hotspot.

Serum human epididymis protein 4 is associated with disease severity in patients with IgA nephropathy

BACKGROUND

Human epididymis protein 4 (HE4) is a promising tumor biomarker primarily utilized for the detection of ovarian cancer. However, its potential as a novel diagnostic indicator for immunoglobulin A nephropathy (IgAN) remains unknown. The objective of this study was to investigate the feasibility of serum HE4 as a novel biomarker for patients with IgAN.

METHODS

This study enrolled a total of 89 hospitalized patients with IgAN at Peking University Shenzhen Hospital between July 2020 and December 2022, along with 60 healthy control subjects matched for sex and age without evidence of comorbidities. Serum HE4 levels were measured using the Abbott Alinity automated immune analyzer, and the correlation between serum HE4 levels and biochemical markers of renal damage as well as clinicopathologic features in IgAN patients were analyzed.

RESULTS

In this study, serum HE4 levels were significantly elevated in patients with IgAN compared to healthy controls (116.43 ± 103.61 pmol/L vs. 35.57 ± 9.33 pmol/L, p < 0.001). There was a positive correlation between serum HE4 levels and blood urea nitrogen (r = 0.58, p < 0.001), creatinine (r = 0.73, p < 0.001), cystatin C (r = 0.82, p < 0.001), β2-microglobulin (r = 0.77, p < 0.001), α1-microglobulin (r = 0.75, p < 0.001), and glomerulosclerosis ratio (r = 0.56, p < 0.001). Conversely, a negative correlation was observed between serum HE4 levels and hemoglobin (r = -0.42, p < 0.001), albumin (r = -0.44, p < 0.001) and estimated glomerular filtration rate (eGFR) (r = -0.83, p < 0.001). In HE4+ IgAN patients, a higher glomerulosclerosis ratio (p < 0.01) and lower eGFR levels (p < 0.001) were observed compared to HE4- patients. Furthermore, patients with higher pathological classification grade also had higher serum HE4 levels.

CONCLUSIONS

Serum HE4 levels were significantly associated with both renal function and the pathological classification of patients with IgAN, indicating that HE4 may serve as a promising biomarker for assessing the severity of IgAN.

A rare case of hydatid cyst-associated AA amyloidosis and literature review of hydatid cyst-associated nephropathy

Hydatid disease is an infective picture caused by echinococcus, which progresses with cysts in various organs, especially in the liver. Renal involvement is an unusual location in the course of the disease. Although mostly asymptomatic renal cysts are seen, rarely glomerular or tubular associated nephropathy develops. In addition, the development of amyloidosis has been shown previously in patients with untreated chronic hydatid cysts. We wanted to bring a 27-year-old female patient with a 10-year history of hydatid cyst and AA amyloidosis to the literature. In addition, in our literature review for hydatid disease-associated nephropathies, we brought together data from 12 studies involving a total of 21 cases. Of these cases, 3 were membranous glomerulonephritis (MGN), 5 were, membranoproliferative glomerulonephritis (MPGN), 1 was minimally change disease (MCD), 5 were AA amyloidosis (including our case), 3 were immunoglobulin A nephropathy (IgAN), 1 was tubulointerstitial nephritis (TIN), 1 was chronic kidney disease (CKD), 1 was TIN with mesangioproliferative glomerulonephritis (MesPGN), 1 was TIN with IgAN, 1 was MPGN with immunoglobulin M nephropathy (IgMN). In this way, we wanted to shed light on the relationship between Echinococcus and nephropathy. In this way, we wanted to emphasise the necessity of doing renal examinations in the follow-up of hydatid cyst patients.

68 Ga-FAPI-04 Detected Hepatic Arteriovenous Malformation in a Patient With IgA Nephropathy

ABSTRACT

A 51-year-old woman with a history of IgA nephropathy was found to have a mass in the right lobe of the liver by abdominal ultrasound. The PET/CT scan revealed elevated 68 Ga-FAPI-04 uptake in the aforementioned lesion, indicating the potential presence of liver cancer. However, subsequent histopathological analysis confirmed it to be an arteriovenous malformation. This case illustrates that 68 Ga-FAPI-04 uptake can occur in arteriovenous malformation and is a benign cause of 68 Ga-FAPI-04 uptake.

Global trends and hotspots in IgA nephropathy: a bibliometric analysis and knowledge map visualization from 2012 to 2023

OBJECTIVES

This study aimed to investigate the distribution patterns and research frontiers of international literature and thus present a holistic bibliometric evaluation of the studies on IgA nephropathy.

METHODS

The Web of Science Core Collection database was searched for studies of IgA nephropathy from January 2012 to March 2023. The keywords and references are analyzed by CiteSpace, while the countries and institutions are analyzed by VOSviewer.

RESULTS

A total of 2987 publications on IgA nephropathy were included. The country with the most publications was China (n = 1299), and the institution with the most publications was Peking University (n = 139). The most frequent keywords were IgA nephropathy (n = 2013), Oxford classification (n = 482), and diseases (n = 433). The keywords that continue to burst out at high intensity are multicenter study and gut microbiota. Moreover, the top five references for burst strength were also listed.

CONCLUSIONS

IgA nephropathy has attracted widespread research interest, particularly in high-prevalence areas. From 2012 to 2023, publications on IgA nephropathy show a linear increase. China is the country with the highest number of publications and Peking University is the institution with the highest number of publications. Current research hotspots and frontiers are mainly multicenter studies related to IgA nephropathy and its exploration with gut microbiota. Overall, we have provided a comprehensive scientometric analysis of IgA nephropathy that will inform researchers and healthcare practitioners.

The complement system in IgAN: mechanistic context for therapeutic opportunities

The complement system plays a crucial role in innate immunity, providing essential defense against pathogens. However, uncontrolled or prolonged activation of the complement cascade can significantly contribute to kidney damage, especially in cases of glomerulonephritis. Immunoglobulin A nephropathy (IgAN), the most prevalent form of primary glomerulonephritis, has growing evidence supporting the involvement of complement alternative and lectin pathways. In fact, patients with IgAN experience complement activation within their kidney tissue, which may be involved in the development of glomerular damage and the progression of IgAN. Complement activation has emerged as a significant area of interest in IgAN, with numerous complement-targeting agents currently being explored within this field. Nevertheless, the exact mechanisms of complement activation and their role in IgAN progression require comprehensive elucidation. This review seeks to contextualize the proposed mechanisms of complement activation within the various stages ("hits") of IgAN pathogenesis, while also addressing the clinical implications and anticipated outcomes of complement inhibition in IgAN.

CKD therapy to improve outcomes of immune-mediated glomerular diseases

The management of immunoglobulin A nephropathy, membranous nephropathy, lupus nephritis, anti-neutrophil cytoplasmic antibody-associated vasculitis, C3 glomerulonephritis, autoimmune podocytopathies and other immune-mediated glomerular disorders is focused on two major treatment goals, preventing overall mortality and the loss of kidney function. Since minimizing irreversible kidney damage best serves both goals, the management of immune-mediated kidney disorders must focus on the two central pathomechanisms of kidney function decline, i.e., controlling the underlying immune disease process (e.g. with immunotherapies) and controlling the non-immune mechanisms of chronic kidney disease (CKD) progression. Here we review the pathophysiology of these non-immune mechanisms of CKD progression and discuss non-drug and drug interventions to attenuate CKD progression in immune-mediated kidney disorders. Non-pharmacological interventions include reducing salt intake, normalizing body weight, avoiding superimposed kidney injuries, smoking cessation and regular physical activity. Approved drug interventions include inhibitors of the renin-angiotensin-aldosterone system and sodium-glucose cotransporter-2. Numerous additional drugs to improve CKD care are currently being tested in clinical trials. Here we discuss how and when to use these drugs in the different clinical scenarios of immune-mediated kidney diseases.

[Activation of intestinal mucosal TLR4/NF-κB pathway is associated with renal damage in mice with pseudo-sterile IgA nephropathy]

Objective To investigate the effect of intestinal mucosal Toll-like receptor 4/nuclear factor κB (TLR4/NF-κB) signaling pathway on renal damage in pseudo-sterile IgA nephropathy (IgAN) mice. Methods C57BL/6 mice were randomly divided into experimental group (pseudosterile mouse model group), control group (IgAN mouse model group), pseudosterile mouse blank group, and normal mouse blank group. Pseudosterile mice were established by intragastric administration of quadruple antibiotics once a day for 14 days. The pseudosterile IgAN mouse model was set up by combination of oral bovine serum albumin (BSA) administration and staphylococcal enterotoxin B (SEB) injection. The pathological changes of renal tissue were observed by immunofluorescence staining and PAS staining, and the intestinal mucosa barrier damage indicators lipopolysaccharide(LPS), soluble intercellular adhesion molecule 1(sICAM-1) and D-lactate(D-LAC) were analyzed by ELISA. Biochemical analysis was used to test 24 hour urine protein, serum creatinine and blood urea nitrogen. The mRNA and protein levels of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and nuclear factor κB (NF-κB) were detected by reverse transcription PCR and Western blot analysis. Results The kidney damage of pseudosterile IgAN mice was more severe than that of IgAN mice, and the expressions of intestinal mucosal barrier damage markers (LPS, sICAM-1 and D-LAC) were significantly increased in pseudosterile IgAN mice. In addition, the expressions of TLR4, MyD88, and NF-κB level were all up-regulated in the intestinal tissues of IgAN pseudosterile mice. Conclusion Intestinal flora disturbance leads to intestinal mucosal barrier damage and induces activation of TLR4 signaling pathway to mediate renal injury in IgAN.

Causal associations between thyroid cancer and IgA nephropathy: a Mendelian randomization study

BACKGROUND

The incidence of kidney disease caused by thyroid cancer is rising worldwide. Observational studies cannot recognize whether thyroid cancer is independently associated with kidney disease. We performed the Mendelian randomization (MR) approach to genetically investigate the causality of thyroid cancer on immunoglobulin A nephropathy (IgAN).

METHODS AND RESULTS

We explored the causal effect of thyroid cancer on IgAN by MR analysis. Fifty-two genetic loci and single nucleotide polymorphisms were related to thyroid cancer. The primary approach in this MR analysis was the inverse variance weighted (IVW) method, and MR‒Egger was the secondary method. Weighted mode and penalized weighted median were used to analyze the sensitivity. In this study, the random-effect IVW models showed the causal impact of genetically predicted thyroid cancer across the IgAN risk (OR, 1.191; 95% CI, 1.131-1.253, P < 0.001). Similar results were also obtained in the weighted mode method (OR, 1.048; 95% CI, 0.980-1.120, P = 0.179) and penalized weighted median (OR, 1.185; 95% CI, 1.110-1.264, P < 0.001). However, the MR‒Egger method revealed that thyroid cancer decreased the risk of IgAN, but this difference was not significant (OR, 0.948; 95% CI, 0.855-1.051, P = 0.316). The leave-one-out sensitivity analysis did not reveal the driving influence of any individual SNP on the association between thyroid cancer and IgAN.

CONCLUSION

The IVW model indicated a significant causality of thyroid cancer with IgAN. However, MR‒Egger had a point estimation in the opposite direction. According to the MR principle, the evidence of this study did not support a stable significant causal association between thyroid cancer and IgAN. The results still need to be confirmed by future studies.

Relationship between arterial stiffness, left ventricular diastolic function, and renal function in chronic kidney disease

AIM

In chronic kidney disease, IgA nephropathy, and left ventricular diastolic dysfunction have prognostic significance as well. However, the relationship between diastolic dysfunction, arterial stiffness, and renal function has not been fully elucidated.

METHODS

79 IgA nephropathy patients (aged 46 ± 11 years) and 50 controls were investigated. Tissue Doppler imaging was used to measure early (Ea) and late (Aa) diastolic velocities. Arterial stiffness was measured by a photoplethysmographic (stiffness index (SI)) and an oscillometric method (aortic pulse wave velocity (PWVao)).

RESULTS

We compared the IgAN patients to a similar cardiovascular risk group with a preserved eGFR. A strong correlation was found between Ea/Aa and SI (p < 0.001), also with PWVao (p < 0.001), just in IgAN, and with eGFR (p < 0.001) in both groups. IgAN patients were divided into groups CKD1-2 vs. CKD3-5. In the CKD 3-5 group, the incidence of diastolic dysfunction increased significantly: 39% vs. 72% (p = 0.003). Left ventricle rigidity (LVR) was calculated, which showed a close correlation with SI (p = 0.009) and eGFR (p = 0.038). By linear regression analysis, the independent predictors of SI were age, E/A, and E/Ea; SI was the predictor of LVR; and E/A and hypertension were the predictors of eGFR.

CONCLUSION

In chronic kidney disease, increased cardiac rigidity and vascular stiffness coexist with decreased renal function, which is directly connected to diastolic dysfunction and vascular stiffness. On the basis of comparing the CKD group to the control group, vascular alterations in very early CKD can be identified.

Glomerulonephritis

Glomerulonephritis (GN) encompasses several disorders that cause glomerular inflammation and injury through an interplay of immune-mediated mechanisms, host characteristics, and environmental triggers, such as infections. GN can manifest solely in the kidney or in the setting of a systemic illness, and presentation can range from chronic and relatively asymptomatic hematuria to fulminant renal failure. Classic acute GN is characterized by hematuria, edema, and hypertension, the latter 2 of which are the consequence of sodium and water retention in the setting of renal impairment. Although presenting signs and symptoms and a compatible clinical history can suggest GN, serologic and urinary testing can further refine the differential diagnosis, and renal biopsy can be used for definitive diagnosis. Treatment of GN can include supportive care, renin-angiotensin-aldosterone system blockade, immunomodulatory therapy, and renal transplant. Prognosis is largely dependent on the underlying cause of GN and can vary from a self-limited course to chronic kidney disease. This review focuses on lupus nephritis, IgA nephropathy, IgA vasculitis, and postinfectious GN.

Novel agents for treating IgA nephropathy

PURPOSE OF REVIEW

In the past, the treatment of IgA nephropathy (IgAN), which is the most common glomerulonephritis worldwide, mostly relied on blockade of the renin-angiotensin system as a central component of so-called supportive therapy as well as on high-dose systemic corticosteroid therapy.

RECENT FINDINGS

The supportive treatment arm has been expanded by the addition of sodium-glucose cotransporter-2 inhibitors, hydroxychloroquine, and, most recently, endothelin A receptor blockers. Treatment with high-dose systemic corticosteroids has become more controversial, with some studies observing no benefit and others documenting the protection of kidney function. However, all recent studies on systemic corticosteroids consistently found significant toxicity. An important novel approach to IgAN, therefore, is therapy with a targeted release formulation of budesonide with preferential release in the distal small intestine, given the mounting evidence for a gut-kidney axis in the pathophysiology of IgAN. In addition, emerging new therapeutic options include a variety of complement inhibitors as well as agents targeting B-cell proliferation and differentiation.

SUMMARY

In recent years, IgAN has become the focus of a considerable number of clinical studies that will significantly advance the development of new therapy strategies.

Correlation of Acoustic Radiation Force Impulse Imaging with Chronicity Markers in Native Renal Biopsy

Introduction. Acoustic Radiation Force Impulse (ARFI) is an ultrasound parameter which has shown promise in assessing liver stiffness, but there are limited data on the correlation of ARFI with chronicity markers in renal biopsies. Objectives. Determine ARFI values in ultrasound and correlate with chronicity markers in renal biopsy. Determine whether ARFI can be used as a non-invasive chronicity predictor compared to renal length, Resistive Index (RI), and cortical thickness. Patients and Methods. Two hundred and fifty patients were enrolled in the study. The ultrasound variables ARFI, renal length, RI, and cortical thickness values were assessed by the radiologist prior to renal biopsy. The biopsy slides were graded as per the Mayo Clinic consensus report scoring system by an experienced pathologist. Results. Among 250 study participants, 167 were males and 83 were females. IgA nephropathy was the most common pathology (n=47;19%), followed by diabetic nephropathy (n=42;17%), membranous nephropathy (n=35;14%), FSGS (n=27;11%), and MCD (n=19; 8%). The mean eGFR was 55.9 ± 42.12 ml/min/1.73 m2. The average renal length was 10.086 ± 1.01 cm. The average cortical thickness was 0.707 ± 0.134 cm. Resistive index was 0.68 ± 0.09. Acoustic radiation force impulse had weak negative correlation (r=-0.286; p=0.0001) with total pathological score and weak positive correlation with eGFR (r=0.279; p=0.0001). RI was a better indicator for histologically evaluated chronicity with positive correlation coefficient (r=0.416; p=0.0005) compared to renal length, cortical thickness, and ARFI. Conclusion. ARFI didn't corelate with the pathological score in renal biopsies. RI had better predictive value for chronicity in native renal biopsies.

Clinical features and prognosis of pregnancy-related renal damage and pregnancy after chronic kidney disease

OBJECTIVE

To explore the clinical features of renal damage related to pregnancy and pregnancy after chronic kidney disease (CKD), providing clinical evidence for the relationship between renal damage and pregnancy.

METHODS

A retrospective analysis was performed on patients admitted to our hospital between March 2013 and February 2021 who had both pregnancy and kidney damage. The study collected pathology results from renal biopsies, 24-hour urinary protein quantity, albumin (Alb), serum creatinine (Scr), blood lipids, coagulation function, blood routine, and other indicators during and after pregnancy.

RESULTS

This study included 82 cases, with 48 cases in the pregnancy-related renal damage group. Thirty-four cases were in the post-CKD pregnancy group. Of the patients, 30 cases (88.24%) had CKD stage 1-2. Results showed better pregnancy and fetal outcomes in the post-CKD pregnancy group compared to the pregnancy-related renal damage group (Ρ was 0.029 and 0.036, respectively). Renal biopsy pathology revealed that 16 cases (33.33%) in the pregnancy-related renal damage group mainly had focal segmental glomerulosclerosis (FSGS), while the post-CKD pregnancy group was dominated by 14 cases (43.75%) of IgA nephropathy. The first blood test indicators revealed that the pregnancy-related renal damage group had lower estimated glomerular filtration (eGFR) and Alb levels compared to the post-CKD pregnancy group (Ρ was 0.003 and 0.000, respectively). Additionally, 24-hour urinary protein quantity, total cholesterol (Tch), triglyceride (TG), and platelet (PLT) counts were higher in the pregnancy-related renal damage group compared to the post-CKD pregnancy group (Ρ was 0.005, 0.001, 0.008, and 0.031, respectively). The abnormal rate of Scr during pregnancy was 41.67% (20/48) in the pregnancy-related renal damage group and 17.39% (4/23) in the post-CKD pregnancy group, with a statistically significant difference (Ρ was 0.043).

CONCLUSION

The pregnancy-related renal damage group is mainly associated with FSGS, while the post-CKD pregnancy group is characterized by IgA nephropathy. Patients with CKD1-2 can have a successful pregnancy after achieving good control of eGFR, albumin, 24-hour urinary protein quantity and other indicators, resulting in better pregnancy and fetal outcomes. Abnormal Scr levels during pregnancy of pregnancy-related renal damage can be improved within 3 months after delivery.

Diagnostic and prognostic value of galactose-deficient IgA1 in patients with IgA nephropathy: an updated systematic review with meta-analysis

Objectives

Galactose-deficient IgA1 (Gd-IgA1) is a critical effector molecule in the pathogenesis of IgA nephropathy (IgAN), a leading renal disease without noninvasive assessment options. This updated systematic review aimed to determine the diagnostic and prognostic value of Gd-IgA1 assessment in biological fluids in patients with IgAN.

Methods

PRISMA guidelines were followed in this review. We searched PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, China Biology Medicine disc, VIP Information/China Science and Technology Journal Database, and WANFANG for studies published between database inception and January 31, 2023. Eligible studies that evaluated aberrant IgA1 glycosylation in IgAN patients relative to controls were identified, and random effects meta-analyses were used to compare Gd-IgA1 levels in different groups. The quality of the evidence was assessed using the Newcastle-Ottawa Scale. This study was registered on PROSPERO (CRD42022375246).

Findings

Of the 2727 records identified, 50 were eligible and had available data. The mean Newcastle-Ottawa Scale score was 7.1 (range, 6-8). Data synthesis suggested that IgAN patients had higher levels of blood and/or urine Gd-IgA1 compared with healthy controls (standard mean difference [SMD]=1.43, 95% confidence interval [CI]=1.19-1.68, P<0.00001), IgA vasculitis patients (SMD=0.58, 95% CI=0.22-0.94, P=0.002), and other kidney disease patients (SMD=1.06, 95% CI=0.79-1.33, P<0.00001). Moreover, patients with IgAN had similar levels of serum Gd-IgA1 compared to first-degree relatives (SMD=0.38, 95% CI= -0.04-0.81, P=0.08) and IgA vasculitis with nephritis patients (SMD=0.12, 95% CI= -0.04-0.29, P=0.14). In addition, ten studies demonstrated significant differences in serum Gd-IgA1 levels in patients with mild and severe IgAN (SMD= -0.37, 95% CI= -0.64--0.09, P=0.009).

Conclusions

High serum and urine Gd-IgA1 levels suggest a diagnosis of IgAN and a poor prognosis for patients with this immunological disorder. Future studies should use more reliable and reproducible methods to determine Gd-IgA1 levels.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022375246, identifier CRD42022375246.

[State-of-the-art paradigm of corticosteroid therapy for immune-mediated inflammatory kidney diseases]

Since 1950's corticosteroids (CS) have remained the cornerstone of immunosuppressive therapy for immune-mediated kidney diseases. However multiple adverse events, associated with the prolonged CS therapy, became the basis for the development of novel treatment approaches. Current evidence supports the implementation of the steroid-sparing regimens for the treatment of different types of glomerulonephritis. Randomised controlled trial PEXIVAS demonstrated the efficacy and safety of early steroid tapering, starting from the second week of therapy, in patients with ANCA-associated vasculitis with kidney involvement. Several trials showed the efficacy of oral prednisolone 0.3-0.5 mg/kg/daily as a part of multitarget therapy for severe proliferative lupus nephritis. A combination of calcineurin inhibitors and low-dose CS are effective for remission induction in membranous nephropathy, as well as the steroid-free rituximab regimen for the patients with moderate risk of disease progression. Medium dose CS showed promising effect in patients with IgA-nephropathy. Long-term high dose CS remain the standard-of-care for the treatment of minimal change disease and focal segmental glomerulosclerosis, however patients with steroid-dependent and relapsing disease tacrolimus and rituximab can help to achieve steroid-sparing effect. The role of CS pulse-therapy is currently debated, nevertheless it remains a compulsory treatment in several conditions. Thus, overall trend is directed towards the minimization of the maximal doses of CS and/or treatment duration. However, to implement this approach morphological verification of the diagnosis and personalized assessment of the potential risk and benefit are required.

Prevalence and distribution of primary glomerular diseases in Africa: a systematic review and meta-analysis of observational studies

Glomerulonephritis (GN) is a predominant cause of kidney failure in Africa. The prevalence of primary GNs varies widely across Africa depending on the relative proportion of secondary GNs and genetic predispositions. We assessed the overall and sub-regional prevalence of primary GN and its histologic subtypes in Africa. We searched PubMed, EMBASE and African Journals Online for studies of biopsy-proven primary GNs across all age groups in Africa published between 2010 and 2022. Data for primary GNs [minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), mesangioproliferative GN (MesPGN), membranoproliferative GN (MPGN), post-infectious GN (PIGN), IgA Nephropathy (IgAN), and crescentic GN (CresGN)] were extracted. Pooled prevalence was determined using the random effects model. Seventeen eligible articles (n = 6,494 individuals) from 8 African countries met the inclusion criteria. The overall pooled prevalence of FSGS, MCD, MN, MPGN, MesPGN, PIGN, IgAN and CresGN was 26.10%, 22.40%, 8.40%, 6.40%, 6.40%, 2.60%, 2.60%, 1.40%, respectively. Only 4 studies (23.5%) used light microscopy (LM), immunofluorescence (IF), and electron microscopy (EM) for diagnosis. There were significant differences in the distribution of histologic subtypes in the paediatric compared to the adult population and across geographic sub-regions, with West Africa having a higher prevalence of FSGS. Overall, the dominance of FSGS across most regions and age groups has implications for disease diagnosis and ongoing care. Research efforts to understand the impact of this trend on kidney disease outcomes and efforts to improve kidney biopsy practice as a means of early disease detection are needed in Africa.

T Follicular Helper Cells in Tertiary Lymphoid Structure Contribute to Renal Fibrosis by IL-21

Tertiary lymphoid structure (TLS) represents lymphocyte clusters in non-lymphoid organs. The formation and maintenance of TLS are dependent on follicular helper T (TFH) cells. However, the role of TFH cells during renal TLS formation and the renal fibrotic process has not been comprehensively elucidated in chronic kidney disease. Here, we detected the circulating TFH cells from 57 IgAN patients and found that the frequency of TFH cells was increased in IgA nephropathy patients with renal TLS and also increased in renal tissues from the ischemic-reperfusion-injury (IRI)-induced TLS model. The inducible T-cell co-stimulator (ICOS) is one of the surface marker molecules of TFH. Remarkably, the application of an ICOS-neutralizing antibody effectively prevented the upregulation of TFH cells and expression of its canonical functional mediator IL-21, and also reduced renal TLS formation and renal fibrosis in IRI mice in vivo. In the study of this mechanism, we found that recombinant IL-21 could directly promote renal fibrosis and the expression of p65. Furthermore, BAY 11-7085, a p65 selective inhibitor, could effectively alleviate the profibrotic effect induced by IL-21 stimulation. Our results together suggested that TFH cells contribute to TLS formation and renal fibrosis by IL-21. Targeting the ICOS-signaling pathway network could reduce TFH cell infiltration and alleviate renal fibrosis.

Genome-Wide Association Studies for Albuminuria of Nondiabetic Taiwanese Population

INTRODUCTION

Chronic kidney disease, which is defined by a reduced estimated glomerular filtration rate and albuminuria, imposes a large health burden worldwide. Ethnicity-specific associations are frequently observed in genome-wide association studies (GWAS). This study conducts a GWAS of albuminuria in the nondiabetic population of Taiwan.

METHODS

Nondiabetic individuals aged 30-70 years without a history of cancer were enrolled from the Taiwan Biobank. A total of 6,768 subjects were subjected to a spot urine examination. After quality control using PLINK and imputation using SHAPEIT and IMPUTE2, a total of 3,638,350 single-nucleotide polymorphisms (SNPs) remained for testing. SNPs with a minor allele frequency of less than 0.1% were excluded. Linear regression was used to determine the relationship between SNPs and log urine albumin-to-creatinine ratio.

RESULTS

Six suggestive loci are identified in or near the FCRL3 (p = 2.56 × 10-6), TMEM161 (p = 4.43 × 10-6), EFCAB1 (p = 2.03 × 10-6), ELMOD1 (p = 2.97 × 10-6), RYR3 (p = 1.34 × 10-6), and PIEZO2 (p = 2.19 × 10-7). Genetic variants in the FCRL3 gene that encode a secretory IgA receptor are found to be associated with IgA nephropathy, which can manifest as proteinuria. The PIEZO2 gene encodes a sensor for mechanical forces in mesangial cells and renin-producing cells. Five SNPs with a p-value between 5 × 10-6 and 5 × 10-5 are also identified in five genes that may have a biological role in the development of albuminuria.

CONCLUSION

Five new loci and one known suggestive locus for albuminuria are identified in the nondiabetic Taiwanese population.

Predictors of Gross Hematuria After SARS-CoV-2 mRNA Vaccination in Patients with IgA Nephropathy

Key Points

Little is known about the clinical characteristics of patients with immunoglobulin A nephropathy (IgAN) who present with gross hematuria in relation to SARS-CoV-2 mRNA vaccination. The relationship between the clinical features in patients with IgAN at the time of SARS-CoV-2 mRNA vaccination and the subsequent appearance of gross hematuria was investigated. This study demonstrates the clinical significance of microscopic hematuria in patients with IgAN as a predictor of gross hematuria after SARS-CoV-2 mRNA vaccination.

Background

There have been several reports of immunoglobulin A nephropathy (IgAN) patients with gross hematuria and acute deterioration of urinary findings and kidney function after severe acute respiratory syndrome coronavirus 2 mRNA vaccination. Recent case series studies have indicated a possible link between the status of urinary findings at the time of vaccination and the subsequent appearance of gross hematuria. In this study, we aimed to determine whether the status of prevaccination urinary findings was associated with postvaccination gross hematuria in patients already diagnosed with IgAN.

Methods

Outpatients with IgAN who had been followed up before vaccination were included. We analyzed the association between the remission of prevaccination microscopic hematuria (urine sediment <5 red blood cells/high-power field) or proteinuria (<0.3 g/gCr) and postvaccination gross hematuria.

Results

A total of 417 Japanese patients with IgAN (median age, 51 years; 56% female; eGFR, 58 ml/min per 1.73 m2) were included. The frequency of gross hematuria after vaccination was higher in 20 of 123 patients (16.3%) with microscopic hematuria than in 5 of 294 patients (1.7%) without microscopic hematuria before vaccination (P < 0.001). There was no association between prevaccination proteinuria and postvaccination gross hematuria. After adjusting for potential confounders, such as sex (female), age (younger than 50 years), eGFR (≥60 ml/min per 1.73 m2), and histories of tonsillectomy and corticosteroid therapy, prevaccination microscopic hematuria was still associated with postvaccination gross hematuria (odds ratio, 8.98; P < 0.001). As the severity of prevaccination microscopic hematuria increased, the incidence of postvaccination gross hematuria increased (P < 0.001).

Conclusions

Prevaccination microscopic hematuria in patients with IgAN is a major predictor of postvaccination gross hematuria, regardless of potential confounders, including previous treatments of IgAN.

Comparison between hydroxychloroquine and systemic corticosteroids in IgA nephropathy: a two-year follow-up study

BACKGROUND

Hydroxychloroquine (HCQ) is recommended as a treatment for IgA nephropathy (IgAN) to control proteinuria. The long-term effects of HCQ compared to systemic corticosteroid therapy remain unclear.

METHODS

We conducted a retrospective case‒control study at Peking University First Hospital. Thirty-nine patients with IgAN who received HCQ for at least 24 months without corticosteroids (CSs) or other immunosuppressive agents were included. Thirty-nine matched patients who received systemic CS therapy were selected using propensity score matching. Clinical data over a 24-month period were compared.

RESULTS

In the HCQ group, the level of proteinuria decreased from 1.72 [1.44, 2.35] to 0.97 [0.51, 1.37] g/d (-50.5 [-74.0, -3.4] %, P < 0.001) at 24 months. A significant decline in proteinuria was also found in the CS group, but no significant differences were found between the HCQ group and CS group in the levels of proteinuria (0.97 [0.51, 1.37] vs. 0.53 [0.25, 1.81] g/d, P = 0.707) and change rates (-50.5% [-74.0%, -3.4%] vs. -63.7% [-78.5%, -24.2%], P = 0.385) at 24 months. In addition, the decline rates of eGFR between the HCQ and CS groups were comparable (-7.9% [-16.1%, 5.8%] vs. -6.6% [-14.9%, 5.3%], P = 0.758). More adverse events were observed in the CS group.

CONCLUSIONS

Long-term use of HCQ can maintain stable renal function with minimal side effects. In patients who cannot tolerate corticosteroids, HCQ might be an effective and safe supportive therapy for IgAN.

cnm-positive Streptococcus mutans is associated with galactose-deficient IgA in patients with IgA nephropathy

The presence of Streptococcus mutans expressing Cnm protein encoded by cnm (cnm-positive S. mutans) in the oral cavity is associated with immunoglobulin A (IgA) nephropathy (IgAN). However, the precise mechanism by which cnm-positive S. mutans is involved in the pathogenesis of IgAN remains unclear. The present study evaluated glomerular galactose-deficient IgA1 (Gd-IgA1) to clarify the association between the presence of cnm-positive S. mutans and glomerular Gd-IgA1 in patients with IgAN. The presence of S. mutans and cnm-positive S. mutans was evaluated by polymerase chain reaction in saliva specimens from 74 patients with IgAN or IgA vasculitis. Immunofluorescent staining of IgA and Gd-IgA1 using KM55 antibody in clinical glomerular tissues was then performed. There was no significant association between the glomerular staining intensity of IgA and the positive rate of S. mutans. However, there was a significant association between the glomerular staining intensity of IgA and the positive rate of cnm-positive S. mutans (P < 0.05). There was also a significant association between the glomerular staining intensity of Gd-IgA1 (KM55) and the positive rate of cnm-positive S. mutans (P < 0.05). The glomerular staining intensity of Gd-IgA1 (KM55) was not associated with the positive rate of S. mutans. These results suggest that cnm-positive S. mutans in the oral cavity is associated with the pathogenesis of Gd-IgA1 in patients with IgAN.

Intestinal permeability in patients with IgA nephropathy and other glomerular diseases: an observational study

BACKGROUND

A dysregulated 'gut-kidney axis' may contribute to immunoglobulin A nephropathy (IgAN). We studied whether IgAN patients have disturbed intestinal permeability.

METHODS

In a prospective, cross sectional, pilot study we assessed intestinal permeability in 35 IgAN patients, 18 patients with non-IgAN glomerulonephritides (GNs) and 19 healthy controls. After an overnight fast, trial participants ingested a multi-sugar solution and samples were obtained from 0 to 2, 2 to 5- and 5 to 24-h urine portions. Urinary sugar concentrations were quantified using isocratic ion-exchange high performance liquid chromatography. Indices of small intestinal permeability (0-2-h lactulose/L-rhamnose (L/R) ratio), distal small intestinal and proximal colonic permeability (2-5-h sucralose/erythritol (S/E) ratio) and colonic permeability (5-24-h sucralose/erythritol (S/E) ratio) were evaluated. Associations between groups and indices of intestinal permeability were investigated by a linear mixed model.

RESULTS

Small intestinal permeability (0-2 h L/R-ratio) was significantly increased in patients with glomerular diseases versus healthy controls. More precisely, increased small intestinal permeability was exclusively noted in non-IgAN GN patients, whereas IgAN patients exhibited a trend towards elevated small intestinal permeability. In total, 54% of patients with IgAN and 67% of non-IgAN GN patients had increased small intestinal permeability. Neither distal small intestinal and proximal colonic permeability nor colonic gut permeability indices (i.e., 2-5 h and 5-24 h S/E ratios) were significantly different between controls and any of the GN patient groups.

CONCLUSION

The present single center pilot study suggests that disturbed intestinal permeability is common in patients with glomerular diseases and is not specific for IgAN.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register DRKS00021533, Date: 24.04.2020.

Gut Microbiota Alterations and Primary Glomerulonephritis in Children: A Review

The article summarizes the current evidence on the impact of microbiota alterations on immune-mediated primary glomerulonephritis in children. In particular, the focus is on the link between dysbiosis and the onset or recurrence of idiopathic nephrotic syndrome, immunoglobulin A nephropathy, and membranous nephropathy. The aim is to describe possible pathomechanisms, differences in gut microbiota composition between pediatric patients and healthy controls, and possible usage of microbiota manipulations in supportive therapy. On this basis, we attempt to indicate directions for further research in that field.

Guben Tongluo Formula Protects LPS-induced Damage in Lamina Propria B Lymphocytes Through TLR4/MyD88/NF-κB Pathway

OBJECTIVE

The main pathological feature of immunoglobulin A nephropathy (IgAN), an autoimmune kidney disease, is the deposition of IgA immune complexes, accompanied by mesangial cell proliferation and elevated urine protein. The Guben Tongluo formula (GTF) is a traditional Chinese medicine prescription, which has predominant protective effects on IgAN. However, the therapeutic mechanism of the GTF in IgAN remains elusive. The present study aimed to determine the effects of GTF in treating IgAN via regulating the TLR4/MyD88/NF-κB pathway.

METHODS

In the present study, lamina propria B lymphocytes were treated with different concentrations of lipopolysaccharide (LPS) (0, 1, 5, 10 and 20 ng/mL). Flow cytometry was used to define positive CD86+CD19+ cells. CCK-8 assay was used to examine cell proliferation. RNAi was used to induce TLR4 silencing. qRT-PCR and Western blotting were used to determine gene expression.

RESULTS

It was found that the LPS dose-dependently increased the content of IgA and galactose-deficient IgA1 (Gd-IgA), the levels of TLR4, Cosmc, MyD88 and phosphorylated (p)-NF-κB, and the ratio of CD86+CD19+ and IgA-producing B cells. However, the TLR4 knockdown reversed the role of LPS. This suggests that TLR4 mediates the effects of LPS on lamina propria B lymphocytes. Furthermore, the GTF could dose-dependently counteract the effects of LPS and TLR4 overexpression on lamina propria B lymphocytes through the TLR4/MyD88/NF-κB pathway.

CONCLUSION

Collectively, these results demonstrate that the GTF can regulate the TLR4/MyD88/NF-κB pathway to treat IgAN model lamina propria B lymphocytes stimulated by LPS.

Orange-derived and dexamethasone-encapsulated extracellular vesicles reduced proteinuria and alleviated pathological lesions in IgA nephropathy by targeting intestinal lymphocytes

Current evidence highlights the critical role of the gut-kidney axis in the pathogenesis of IgA nephropathy (IgAN). However, few attempts have been made to explore targeted intestinal immunity therapy. This research aims to develop an oral intestine targeting medication based on extracellular vesicles (EVs) and investigate its therapeutic efficacy in IgAN. EVs were isolated from orange juice and electroporated with dexamethasone sodium phosphate (DexP). After oral administration, EVs-DexP was picked up by lymphocytes in the submucosal area of ileocecum. EVs-DexP outperformed DexP not only in suppressing lymphocyte stimulation in vitro but also in alleviating renal pathological lesions in the IgAN mouse model. Clinical improvement was accompanied by a reducing IgA secreted by the intestine and a decreasing IgA + B220 + lymphocytes in Peyer’s patches. The present study develops a cost-effective, biofriendly EVs-based glucocorticoid strategy for IgAN.

Increased proportion of follicular helper T cells is associated with B cell activation and disease severity in IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis, characterized by glomerular deposition of IgA immune complexes, mainly produced by B cells under the regulation of CD4⁺T cells. However, the alterations of specific CD4⁺T cell subsets and the mechanism of B cells activation in IgAN remain unclear. Therefore, we aimed to investigate the landscape characteristics and role of CD4⁺T cells in the progression of IgAN. We identified that the proportion of Th2, Th17 and Tfh (follicular helper T) cells in patients with IgAN was significantly higher than that of healthy controls (P < 0.05). Single-cell RNA sequencing of peripheral blood mononuclear cells (PBMCs) showed that Th cells and B cells in patients with IgAN were more activated. Correspondingly, multiplex immunohistochemistry staining of renal biopsy showed increased infiltration of CD4⁺T and B cells in the kidneys of patients with IgAN. The degree of infiltration was positively correlated with the degree of renal damage. Interestingly, the proportion of Tfh cells in peripheral blood was positively correlated with the severity of proteinuria. Moreover, the proximity position of Tfh cells and B cells suggested that cell-cell interactions between Tfh and B cells were happening in situ. Intercellular communication analysis also showed enhanced interaction between Tfh cells and B cells in IgAN. Our findings suggested that Tfh cells of patients possibly contributed to the progression of IgAN by activating B cells via cell-cell interactions and TNFSF14-TNFRSF14 may be an underlying signaling pathway.

Gut Microbiome Characteristics in IgA Nephropathy: Qualitative and Quantitative Analysis from Observational Studies

Background

Recent data indicate the importance of gut-kidney axis in the pathogenesis of Immunoglobulin A nephropathy (IgAN). Growing evidence suggests the alterations of diversity and composition of gut microbiome among patients with IgAN, however, the details are not yet fully understood.

Methods

Eligible studies comparing the gut microbiome between patients with IgAN and non-IgAN individuals were systematically searched from PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure, and ClinicalTrials.gov. The primary outcomes were alpha- and beta-diversity, and the differences in gut microbiota composition between patients with IgAN and non-IgAN persons. Qualitative analysis and meta-analysis were performed according to available data.

Results

Eleven cross-sectional studies, including 409 patients with IgAN and 243 healthy controls, were enrolled. No significant differences in the diversity and enrichment of gut bacteria were found between IgAN and healthy individuals, whereas the beta-diversity consistently showed significant microbial dissimilarities among the two groups. Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, Fusobacteria, and Verrucomicrobia were the dominant phyla, however, no significant differences were found between IgAN patients and healthy controls at the phylum level. The genera, Streptococcus and Paraprevotella showed a higher proportion in patients with IgAN compared to healthy individuals, whereas Fusicatenibacter showed a lower abundance according to meta-analysis. Qualitative analyses suggested that Escherichia-Shigella might be increased in IgAN patients; the genera, Clostridium, Prevotella 9,and Roseburia, members of Ruminococcaceae and Lachnospiraceae families, were likely to have decreased abundances in patients with IgAN compared to healthy individuals.

Conclusion

Gut microbiota dysbiosis was demonstrated in IgAN, which might be involved in the pathogenesis of IgAN. Further studies are needed to confirm the findings of this study, due to the substantial heterogeneity.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier PROSPERO (CRD42022304034).