The role of tonsillectomy in IgA nephropathy

The efficacy and safety of hydroxychloroquine versus leflunomide in patients with IgA nephropathy: a single-center experience

PURPOSE

To date, our understanding of IgA nephropathy (IgAN) pathophysiology has remained incomplete; therefore, treatment remains largely empiric, and the efficacy and safety of immunosuppressants remain controversial. We aimed to assess the efficacy and safety of hydroxychloroquine and leflunomide therapy in a retrospective cohort of patients with IgAN.

METHODS

We screened the IgAN registration database in our department, and a total of 159 kidney patients with biopsy-confirmed IgAN were enrolled, with 57 patients receiving hydroxychloroquine plus a renin-angiotensin system inhibitor (hydroxychloroquine group), 52 patients receiving leflunomide plus a renin-angiotensin system inhibitor (leflunomide group), and 50 patients receiving only a renin-angiotensin system inhibitor (renin-angiotensin system inhibitor-only group). Changes in proteinuria, hematuria, and the estimated glomerular filtration rate (eGFR), as well as adverse events, were analyzed during the follow-up period.

RESULTS

At the end of 6-month follow-up, proteinuria significantly decreased by 70.36 (57.54, 79.33)%, 57.29 (46.79, 67.29)% and 41.20 (25.76, 48.94)% in the hydroxychloroquine, leflunomide and renin-angiotensin system inhibitor-only groups, respectively, compared to baseline (all P values < 0.001). Hematuria significantly decreased by 71.07 (56.48, 82.47)% in the leflunomide group (P < 0.001). The eGFR improved by 3.72 ± 2.97%, 3.16 ± 2.00% and 1.91 ± 2.41%, respectively, in the hydroxychloroquine, leflunomide and renin-angiotensin system inhibitor-only groups, but without statistical significance. No serious adverse events occurred during the follow-up period.

CONCLUSION

Both hydroxychloroquine combined with a renin-angiotensin system inhibitor and leflunomide combined with a renin-angiotensin system inhibitor were more effective than a renin-angiotensin system inhibitor alone in improving proteinuria in IgAN patients. Hydroxychloroquine was more effective in reducing proteinuria, and leflunomide showed superiority in reducing hematuria. Our results need to be verified in large-scale randomized controlled trials.

Genome-wide association analyses define pathogenic signaling pathways and prioritize drug targets for IgA nephropathy

IgA nephropathy (IgAN) is a progressive form of kidney disease defined by glomerular deposition of IgA. Here we performed a genome-wide association study of 10,146 kidney-biopsy-diagnosed IgAN cases and 28,751 controls across 17 international cohorts. We defined 30 genome-wide significant risk loci explaining 11% of disease risk. A total of 16 loci were new, including TNFSF4/TNFSF18, REL, CD28, PF4V1, LY86, LYN, ANXA3, TNFSF8/TNFSF15, REEP3, ZMIZ1, OVOL1/RELA, ETS1, IGH, IRF8, TNFRSF13B and FCAR. The risk loci were enriched in gene orthologs causing abnormal IgA levels when genetically manipulated in mice. We also observed a positive genetic correlation between IgAN and serum IgA levels. High polygenic score for IgAN was associated with earlier onset of kidney failure. In a comprehensive functional annotation analysis of candidate causal genes, we observed convergence of biological candidates on a common set of inflammatory signaling pathways and cytokine ligand-receptor pairs, prioritizing potential new drug targets.

Characteristics of children with IgA nephropathy

BACKGROUND

We analyzed the demographic and clinical characteristics of children with immunoglobulin A (IgA) nephropathy using data in the first pages of electronic health records of 22 hospitals from 2016 to 2018.

METHODS

Information collected included gender, age, infection site, etiological infection, acute kidney injury (AKI), and chronic kidney disease (CKD) stages 2-5. We analyzed the gender and age distribution of children with IgA nephropathy, the characteristics of children complicated with AKI and CKD, and the influence of geographical distribution and economic status on the incidence of IgA nephropathy.

RESULTS

We included a total of 4006 patients with IgA nephropathy. Incidence in males gradually increased with age. Seventy-nine cases (1.97%) had AKI. We found no significant difference in gender (P = 0.19) or age (P = 0.07) between the AKI and non-AKI groups. Twenty-nine patients had CKD (0.72%), who were significantly older than those in the non-CKD group (P < 0.0001). The incidence of IgA nephropathy in less-developed areas was significantly lower than that in developed areas (P = 0.0002).

CONCLUSIONS

The incidence of IgA nephropathy was high mainly in males. Age was an important factor affecting CKD. The disease was related to environment and economic status.

IMPACT

We analyze the demographic and clinical characteristics of children with immunoglobulin A (IgA) nephropathy using data in the first pages of electronic health records. This is a large sample, multi-center study. The incidence of IgA nephropathy in males increased gradually with age. Age was an important factor affecting CKD. The disease was related to environment and economic status.

The Gut and Kidney Crosstalk in Immunoglobulin A Nephropathy

Immunoglobulin A nephropathy(IgAN) is the most common primary glomerulonephritis worldwide. The working model for the pathogenesis of IgAN involves a multistep process starting from the production of galactose-deficient and polymeric immunoglobulin A-1 (gd-IgA1) that enters systemic circulation from gut-associated lymphoid tissue (GALT). Galactose-deficient IgA are targeted by endogenous IgG, leading to the formation of circulating immune complexes that deposit in the mesangium and resulting in glomerular inflammation. Disease onset and relapses are often associated with gut infections, supporting the hypothesis that the gut plays an important pathogenic role. In the presence of microbial pathogens or food antigens, activated dendritic cells in the gut mucosa induce T cell dependent and independent B cell differentiation into IgA secreting plasma cells. In IgAN patients, this promotes the systemic release of mucosal gd-IgA1. Not all bacterial strains have the same capacity to elicit IgA production, and little is known about the antigen specificity of the pathogenic gd-IgA1. However, efficacy of treatments targeting gut inflammation support a pathogenic link between the bowel immune system and IgAN. Herein, we review the evidence supporting the role of gut inflammation in IgAN pathogenesis.

Development and Evaluation of a Robust Sandwich Immunoassay System Detecting Serum WFA-Reactive IgA1 for Diagnosis of IgA Nephropathy

Aberrant glycosylation of IgA1 is involved in the development of IgA nephropathy (IgAN). There are many reports of IgAN markers focusing on the glycoform of IgA1. None have been clinically applied as a routine test. In this study, we established an automated sandwich immunoassay system for detecting aberrant glycosylated IgA1, using Wisteria floribunda agglutinin (WFA) and anti-IgA1 monoclonal antibody. The diagnostic performance as an IgAN marker was evaluated. The usefulness of WFA for immunoassays was investigated by lectin microarray. A reliable standard for quantitative immunoassay measurements was designed by modifying a purified IgA1 substrate. A validation study using multiple serum specimens was performed using the established WFA-antibody sandwich automated immunoassay. Lectin microarray results showed that WFA specifically recognized N-glycans of agglutinated IgA1 in IgAN patients. The constructed IgA1 standard exhibited a wide dynamic range and high reactivity. In the validation study, serum WFA-reactive IgA1 (WFA+-IgA1) differed significantly between healthy control subjects and IgAN patients. The findings indicate that WFA is a suitable lectin that specifically targets abnormal agglutinated IgA1 in serum. We also describe an automated immunoassay system for detecting WFA+-IgA1, focusing on N-glycans.

Immunoglobulin A nephropathy is characterized by anti-commensal humoral immune responses

IgA nephropathy (IgAN) is a leading cause of kidney failure, yet little is known about the immunopathogenesis of this disease. IgAN is characterized by deposition of IgA in the kidney glomeruli, but the source and stimulus for IgA production are not known. Clinical and experimental data suggest a role for aberrant immune responses to mucosal microbiota in IgAN, and in some countries with high disease prevalence, tonsillectomy is regarded as standard-of-care therapy. To evaluate the relationship between microbiota and mucosal immune responses, we characterized the tonsil microbiota in patients with IgAN versus nonrelated household-matched control group participants and identified increased carriage of the genus Neisseria and elevated Neisseria-targeted serum IgA in IgAN patients. We reverse-translated these findings in experimental IgAN driven by BAFF overexpression in BAFF-transgenic mice rendered susceptible to Neisseria infection by introduction of a humanized CEACAM-1 transgene (B × hC-Tg). Colonization of B × hC-Tg mice with Neisseria yielded augmented levels of systemic Neisseria-specific IgA. Using a custom ELISPOT assay, we discovered anti-Neisseria–specific IgA-secreting cells within the kidneys of these mice. These findings suggest a role for cytokine-driven aberrant mucosal immune responses to oropharyngeal pathobionts, such as Neisseria, in the immunopathogenesis of IgAN. Furthermore, in the presence of excess BAFF, pathobiont-specific IgA can be produced in situ within the kidney.

Clinical and Pathological Implications of Increases in Tonsillar CD19+CD5+ B Cells, CD208+ Dendritic Cells, and IgA1-positive Cells of Immunoglobulin A Nephropathy

OBJECTIVE

Several studies indicated that tonsillectomy can improve the prognosis of patients with immunoglobulin A nephropathy (IgAN). However, the relationship between tonsillar immunity and IgAN is still unclear.

METHODS

A total of 14 IgAN patients were recruited in the current study from May 2015 to April 2016 in Tongji Hospital. B cells, dendritic cells (DCs), and IgA1 positive cells in human tonsils were detected using immunofluorescence and immunohistochemistry. Correlations between these cells and clinicopathologic features were evaluated.

RESULTS

CD19+CD5+ B cells were predominantly located in germinal centers and mantle zones of lymphoid follicles, the CD208+ DCs were distributed in the interfollicular and subepithelial area, and IgA1-positive cells were predominantly detected in mantle zones of lymphoid follicles and subepithelial tissues. The numbers of CD19+CD5+ B cells, CD208+ DCs, and IgA1-positive cells in tonsillar tissues from IgAN patients were significantly higher than those in the normal controls (P<0.01, respectively). CD19+CD5+ B cells, CD208+ DCs, and IgA1-positive cells in tonsillar tissues were significantly associated with 24-h proteinuria levels and tubular atrophy/interstitial fibrosis of IgAN.

CONCLUSION

CD19+CD5+ B cells, CD208+ DCs, and IgA1-positive cells in tonsillar tissues might be involved in the pathogenesis of IgAN.

IgA Nephropathy: "The Times They Are a-Changin"

Background

Primary IgA Nephropathy (IgA N) is a very common and often progressive glomerular disease. At present, the diagnosis of IgA N is totally dependent on kidney biopsy, but the prospect for a future diagnosis by means of a "liquid" biopsy is promising. A great deal is now understood regarding its diverse clinical and pathological features as well as its epidemiology, genetics, prognosis, and pathogenesis. Treatment approaches are now on increasingly solid evidence-based grounds, but many uncertainties continue to be devil the field. Better means of categorization of patients into a hierarchy of progression risk at the time of diagnosis will undoubtedly refine and personalize treatment decisions.

Summary

The panorama of treatment strategies is undergoing a rapid transformation, largely due to an increase in large randomized clinical trials testing available agents and novel therapeutic classes. It is anticipated that the combination of better prognostic tools and new strategies for treatment of IgA N will alter the landscape of therapeutic algorithms for patients with IgA N.

Key Messages

This review seeks to describe some of the evolutionary changes in the approach to treatment of IgA N, to place them in the context of current management, and to identify knowledge gaps that need to be addressed.

Enumerating the role of properdin in the pathogenesis of IgA nephropathy and its possible therapies

BACKGROUND

IgA nephropathy (IgAN) has become the most prevalent form of glomerulonephritis affecting almost 1.3% of the total population worldwide. It is an autoimmune disorder where the host autoantibody forms an immune complex with the defective galactose-deficient IgA1 and gets deposited at the mesangium and endocapillary region of glomeruli. IgA has the capability to activate alternative and lectin complement cascades which even aggravates the condition. Properdin is directly associated with IgAN by activating and stabilising the alternative complement pathway at the mesangium, thereby causing progressive renal damage.

OBJECTIVE

The present review mainly focuses on correlating the influence of properdin in activating the complement cascade at glomeruli which is the major cause of disease exacerbation. Secondly, we have described the probable therapies and new targets that are under trials to check their efficacy in IgAN.

METHODS

An in-depth research was carried out from different peer-reviewed articles till December 2020 from several renowned databases like PubMed, Frontier, and MEDLINE, and the information was analysed and written in a simplified manner.

RESULTS

Co-deposition of properdin is observed along with IgA and C3 in 75%-100% of the patients. It is not yet fully understood whether properdin inhibition can attenuate IgAN, as many conflicting reports have revealed worsening of IgAN after impeding properdin.

CONCLUSION

With no specific cure still available, the treatment strategies are of great concern to find a better target to restrict the disease progression. More research and clinical trials are required to find out a prominent target to combat IgAN.

IgA Nephropathy: An Interesting Autoimmune Kidney Disease

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. It is a leading cause of chronic kidney disease and progresses to end-stage kidney disease in up to 40% of patients about 20 years after diagnosis. Additionally, IgAN is associated with significant mortality. The diagnosis currently necessitates a kidney biopsy, as no biomarker sufficiently specific and sensitive is available to supplant the procedure. Patients display significant heterogeneity in the epidemiology, clinical manifestations, renal progression, and long-term outcomes across diverse racial and ethnic populations. Recent advances in understanding the underlying pathophysiology of the disease have led to the proposal of a four-hit hypothesis supporting an autoimmune process. To date, there is no disease-specific treatment but, with a better understanding of the disease pathogenesis, new therapeutic approaches are currently being tested in clinical trials. In this review, we examine the multiple facets and most recent advances of this interesting disease.

Tonsillectomy Improved Therapeutic Response in Anti-SRP Myopathy With Chronic Tonsillitis

Chronic tonsillitis has been attracted attention as a source of abnormal immune responses and a possible trigger of autoimmune diseases such as IgA nephritis, IgA vasculitis, palmoplantar pustulosis, psoriasis, rheumatoid arthritis, Behçet’s disease, and myositis. Here we present the first report of anti–signal recognition particle antibody–associated necrotizing myopathy (anti-SRP myopathy) with IgA nephropathy and chronic tonsillitis in which the therapeutic response to intravenous immunoglobulin (IVIG) treatment was dramatically improved after tonsillectomy and accompanied by a rapid increase in ΔIgG, defined as the change in serum IgG levels 2 weeks after the start of IVIG treatment relative to pre-treatment levels. Moreover, serum anti-SRP antibody titers became undetectable after tonsillectomy even though the resected tonsils did not produce anti-SRP antibodies. Tonsillectomy should be considered when chronic tonsillitis is observed in patients with autoimmune diseases showing poor response to treatment, including anti-SRP myopathy.

The potentially therapeutic role of tonsillectomy in the alleviation of several renal diseases apart from IgA nephropathy

Tonsils are located mainly at the gateway of the respiratory tract, and are reportedly one of the secondary lymphatic organs of the immune system. The development of several diseases including IgA nephropathy (IgAN) is associated with inflammatory stimulation and an aberrant immune response of the tonsils. Several studies have reported an improvement in and/or an increase in the stability of the clinicopathological findings of patients with IgAN post tonsillectomy. However, the efficacy in and precise mechanism of the alleviation of symptoms of other renal diseases by tonsillectomy remain unknown. We hypothesize that tonsillectomy may play a potentially therapeutic role in renal diseases apart from IgAN, which are thought to be caused by an impaired regulation of the immune system.

IgA nephropathy in children and in adults: two separate entities or the same disease?

IgA nephropathy (IgAN) is observed in subjects of any age, however perspective and management of this disease are different between adult and pediatrician Nephrologists. Most children with IgAN present with gross hematuria rapidly vanishing or persistent mild microscopic hematuria, which rarely progresses to end stage renal disease (ESRD) over the pediatric observation. The perspective of IgAN in adults is of a slowly progressive glomerular disease with 30-40% probabilities to reach ESRD. However, mild cases of IgAN in children might be missed with manifestation of irreversible damage only decades after the true onset, as 50% of subjects with IgAN enter renal replacement treatment before the age of 50 years. In both adults and children the assessment of risk profile is crucial to avoid overtreatment in benign cases or institute a prompt and valid therapy in potentially progressive cases. In case of common risk factors, new therapeutic opportunities tested in adults might be applied to children with the expectation of similar results. If IgAN is the same disease in spite of different clinical profiles in children and adults, an early intervention may be the correct way to prevent progression decades later. On the contrary, if we are dealing with different clinical entities, the treatment in pediatric and in adult settings must be kept apart. This review addresses to report similarities and differences of IgAN across the life periods in order to reason on the application of newly offered treatments over the entire spectrum of this disease or in focused age indications.

C1GALT1 expression is associated with galactosylation of IgA1 in peripheral B lymphocyte in immunoglobulin a nephropathy

Background

More and more studies demonstrated that genetic variation at C1GALT1 influences Gd-IgA1 level in IgAN. However, whether the expression of β1, 3-galactosyltransferase (β1, 3Gal-T) was influenced may provide insights into how Gd-IgA1 levels are controlled in IgAN.

Methods

Thirty IgAN patients diagnosed in Tianjin Medical University General Hospital from April to September 2018 and 30 healthy volunteers whose age and gender matched with patients were enrolled in this study. Total Gd-IgA1 levels in plasma were determined by ELISA and C1GALT1 levels were determined by RT-PCR. Four databases (PubMed, EMBASE, CNKI, WanFang Medical Network) were searched to identify eligible studies that evaluated a difference in the expression of C1GALT1 in IgAN patients compared with total controls (non-IgAN and health controls). The C1GALT1C1 expression levels, which was indispensable to β1, 3Gal-T of IgA1, was also been compared.

Results

Gd-IgA1 levels were remarkable higher in IgAN patients compared with healthy control. The expression levels of C1GALT1 gene were remarkably down-regulated in IgAN patients compared with healthy control. And the mRNA level of C1GALT1 was inversely correlated to Gd-IgA1 levels. In meta-analysis, six articles including 316 participants that analyzed the expression of β1, 3Gal-T were met inclusion criteria. There was no significant difference in the expression of C1GALT1 between IgAN patients compared with controls. And we found patients with IgAN had lower levels of C1GALT1 gene expression in the B cells compared to controls. The C1GALT1C1 levels in the IgAN patients were not different from the levels in the control group, which were unchanged no matter according to different ethnic population, different control group and different cell source. Two studies including 46 persons compared enzymatic activity of β1, 3Gal-T in B cells, and the result showed the β1, 3Gal-T activity was decreased in B cells.

Conclusions

We found expression levels of C1GALT1 were remarkably downregulated in IgAN patients and negatively correlated with higher levels of Gd-IgA1. Subsequent meta-analysis validated the low expression and activity of β1, 3Gal-T in B cells in patients with IgAN. However, there was no apparent disparity in the aspect of C1GALT1C1 expression between IgAN and control groups.

Triptolide inhibits tonsillar IgA production by upregulating FDC-SP in IgA nephropathy

IgA nephropathy (IgAN) is primarily resulted of qualitative abnormality of IgA. The occurrence of IgAN is associated with affected tonsils which enhances the IgA production via IgA class switching and immuno-activation. Follicular dendritic cell-secreted protein (FDC-SP) was found to be a negative effect for IgA production in tonsil. The previous studies suggested that Triptolide might reduce IgA production by its immunosuppression role. Given this background, this study investigated the mechanisms underlying the role of Triptolide and FDC-SP in the generation of IgA and IgA class switching in tonsil of IgAN patients. Immunohistochemistry and reverse transcription-polymerase chain reaction revealed that the expression of FDC-SP was increased in the tonsils of IgAN patients with Triptolide treatment compared with those without treatment. Meanwhile, the expression of FDC-SP was negatively correlated with IgA inducing cytokines in the tonsils of IgAN patients treated with Triptolide, due to the significant decreased IgA-bearing cells. The expression of FDC-SP in tonsillar tissue was confirmed by double immunofluorescence. Importantly, Triptolide promoted FDC-SP secretion, and correlated negatively with decreased IgA production in isolated FDC-associated clusters, which had been isolated from patients without TW treatment previously. Our study demonstrated that Triptolide might have an impact on FDC-SP production and downregulation of IgA synthesis in the tonsils of IgAN patients, which could be a promising strategy for therapeutic intervention in IgAN patients.

Tonsillectomy plus steroid pulse therapy is the most effective treatment in adult patients with C-Grade I IgA nephropathy, and the weight of the extracted palatine tonsils and Yamamoto scale have no significant correlation with the effects of this treatment

OBJECTIVE

We studied patients who underwent tonsillectomy plus steroid pulse therapy (TSP) for immunoglobulin A nephropathy (IgAN), in order to investigate the clinical factors associated with a positive response to this treatment.

METHODS

We analyzed 118 IgAN patients who underwent TSP. We collected patients' data retrospectively, including age, sex, blood pressure, onset of IgAN, pathological findings of a renal biopsy, serum concentration of creatinine, estimated glomerular filtration rate, serum concentration of protein, urinary protein, hematuria, past history of tonsillitis, the Yamamoto scale, the weight and pathological findings of the extracted palatine tonsils, and the presence or absence of anti-platelet drugs and renin-angiotensin system inhibitors (RAS-I) usage. This study included participants who were over 18 years of age, had undergone tonsillectomy within three months of steroid pulse therapy administered thrice, in whom renal biopsy was performed within a year before treatment, and with follow-up period of over 3 years. Clinical remission (CR) of urinary abnormalities was defined as remission of both proteinuria and hematuria: three consecutive negative results over a 6-month period, with a urinary sediment red blood cell count of <5/HPF, and a proteinuria qualitative reaction of (-) to (±).

RESULTS

The CR rate of all cases was 56.8% and statistical significance was observed with respect to the C-Grade (P =  0.0003, P =  0.028) using both univariate and multivariate analysis. The CR rate of C-Grade І (73.4%) patients was significantly higher than that of C-Grade II patients (39.0%; P =  0.0004) and C-Grade III patients (30.8%; P =  0.003). We analyzed clinical factors in each C-Grade patient. No statistical significance was observed with respect to any of the factors using univariate analysis in C-Grade I patients. The weight of the extracted palatine tonsils and Yamamoto scale showed no statistical significance in every analysis. Fibrosis or hyalinization of the stroma of the palatine tonsils showed statistical significance (P =  0.026) only in the univariate analysis of C-Grade III patients. However, the patient number of C-Grade III was small.

CONCLUSION

Our results indicate that TSP is mostly effective in patients with of C-Grade I IgAN and that the C-Grade reflects the clinical indication for TSP. The weight of the extracted palatine tonsils and Yamamoto scale did not show obvious correlations with the clinical effect of TSP.

Tripterygium Wilfordii inhibits tonsillar IgA production by downregulating IgA class switching in IgA nephropathy

IgA nephropathy (IgAN) is characterized by high serum IgA levels and IgA deposition in the renal mesangium. Recent research has indicated that pathogenic IgA may originate from affected tonsils, where present enhancement of IgA production by IgA class switching and immuno-activation. Tripterygium Wilfordii (TW) was found to be especially effective in IgAN by its’ immunosuppression effect. Given this background, we investigated the mechanisms underlying the role of TW in the generation of IgA and IgA class switching in tonsillar GCs of IgAN patients. Immunohistochemistry and RT-PCR revealed that the expression of thymic stromal lymphopoietin (TSLP) and IgA inducing cytokines were decreased in the tonsils of IgAN patients with TW treatment compared with those without treatment, followed by significantly decreased of IgA-bearing cells. The location of TSLP and IgA inducing cytokines in tonsillar tissue was confirmed by double immunofluorescence. Importantly, TW inhibit TSLP and IgA production in isolated FDC-associated clusters. Serum TSLP levels were decreased and correlated with IgA downregulation in the tonsils and serum of IgAN patients. These data indicated that TW may be involved in IgA production in the tonsils of IgAN patients, inhibiting IgA class switching in IgAN patients through the cooperative roles of AID, TGF-β1, BAFF, and APRIL, highlighting a promising strategy for therapeutic intervention in IgAN.

Aberrant IgA1 Glycosylation in IgA Nephropathy: A Systematic Review

OBJECTIVE

Galactose-deficient IgA1 was evaluated in patients with IgA nephropathy(IgAN) and controls in order to determine the predictive value of galactose-deficient IgA1 in cases of IgA nephropathy.

METHODS

PubMed, EMBASE, Cochrane central register of controlled trials, CNKI, CBM disc, and VIP database were searched to identify eligible studies that evaluated a difference in aberrant IgA1 glycosylation in IgAN patients compared with controls. A meta-analysis was conducted to evaluate the impact of galactose-deficient IgA1(Gd-IgA1) levels in different groups.

RESULTS

A total of 22 studies (n = 1657) met inclusion criteria. The mean Newcastle-Ottawa Scale (NOS) score was 7.2 and ranged from 6 to 8. The standard mean difference(SMD) in the meta-analysis of 20 studies of the level of Gd-IgA1 in the serum and/or supernatant of cultured cells was higher in the IgAN group compared with healthy controls as well as in those with other renal diseases (SMD = 1.76, 95% CI = 1.18-2.34, P<0.00001; SMD = 1.05, 95% CI = 0.05-2.04, P = 0.04). The data synthesis suggested that IgAN patients had similar levels of serum Gd-IgA1, with no significant differences, compared with first-degree relatives and Henoch-Schonlein purpura nephritis (HSPN) patients (MD = 0.04, 95% CI = 0.00-0.08, P = 0.05; MD = -46.03, 95% CI = -217.70-125.64, P = 0.60). In addition, the combined MD of 5 studies indicated that there were no significant differences in Gd-IgA1 levels among patients with varying severities of IgAN (MD = 0.02, 95% CI = -0.02-0.05, P = 0.28).

CONCLUSIONS

The pooled evidence suggests that the level of Gd-IgA1 in the serum or supernatant of cultured cells from peripheral blood or tonsils may be a useful biomarker for predicting IgA nephropathy, though the level of Gd-IgA1 was not significantly associated with disease severity.

Potential diagnostic biomarkers for IgA nephropathy: a comparative study pre- and post-tonsillectomy

OBJECTIVE

The proteins BAFF, ST6GALNAC2, C1GALT1, and COSMC in peripheral blood mononuclear cells (PBMCs) and plasma levels of IgA1 and galactose-deficient IgA1 (Gd-IgA1) are potential biomarkers for IgAN nephropathy. In this study, we comparatively studied the changes of those biomarkers before and after tonsillectomy.

METHODS

Peripheral blood samples were obtained from 16 IgAN patients with pre- and post-tonsillectomy. IgAN was diagnosed based on results from analysis of percutaneous renal biopsy tissue. Peripheral blood samples from three patients without renal diseases (non-IgAN), before and after tonsillectomy, and 16 healthy controls were also examined. BAFF, ST6GALNAC2, C1GALT1, and COSMC mRNA levels in PBMCs were detected using real-time PCR. Plasma IgA1 content was measured by ELISA. Gd-IgA1 levels were determined using the VV lectin-ELISA method.

RESULTS

BAFF, ST6GALNAC2, C1GALT1, and COSMC mRNA levels and the plasma concentrations of IgA1 and Gd-IgA1 in IgAN patients before tonsillectomy were significantly higher than those in healthy controls (P < 0.05). Tonsillectomy significantly increased the expression of BAFF and ST6GALNAC2, and plasma IgA1 level, while it downregulated that of C1GALT1 and COSMC (P < 0.05). However, in non-IgAN patients, tonsillectomy did not affect the mRNA levels of BAFF, ST6GALNAC2, C1GALT1, and COSMC, plasma IgA1 content and Gd-IgA1 level. Positive correlations were established between BAFF and IgA1 (r = 0.604, P < 0.01) and between ST6GALNAC2 and Gd-IgA1 (r = 0.623, P < 0.01).

CONCLUSIONS

Tonsillectomy changes the mRNA levels of BAFF, ST6GALNAC2, C1GALT1, and COSMC in PBMCs, as well as the plasma IgA1 level in IgAN patients. BAFF and ST6GALNAC2 might regulate IgA1 secretion and O-glycosylation.