Association Between Tonsillectomy and Outcomes in Patients With Immunoglobulin A Nephropathy

Aberrant mucosal immunoreaction to tonsillar microbiota in immunoglobulin A nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis worldwide, characterized by mesangial polymeric IgA1 deposition. IgAN is believed to develop owing to aberrant mucosal immunoreaction against commensals in the tonsils. However, the exact interrelation between pathogenic IgA and mucosal microbiota in IgAN patients is unclear.

METHODS

Biopsy-proven IgAN or recurrent tonsillitis (RT) patients who had undergone tonsillectomy were enrolled. We used 16S ribosomal RNA gene amplicon sequencing with a flow cytometry-based bacterial cell sorting technique) and immunoglobulin repertoire sequencing of the IgA heavy chain to characterize IgA-coated bacteria of the tonsillar microbiota (IgA-SEQ) and their corresponding IgA repertoire. Furthermore, we fractionated patient serum using gel-filtration chromatography and performed flow cytometry-based analysis of IgA binding to bacteria cultured from incised tonsils.

RESULTS

Tonsillar proliferation-inducing ligand and B-cell activating factor levels were significantly higher in IgAN than in RT patients. IgA-SEQ for tonsillar microbiota revealed the preferential binding ability of IgA to Bacteroidetes in IgAN tonsils compared with those from RT patients. Expression of immunoglobulin heavy (IGH) constant alpha 1 with IGH variable 3-30 was significantly higher in IgAN than that in RT, and positively correlated with the IgA-coated enrichment score of Bacteroidetes. Serum polymeric IgA, comprising high levels of GdIgA1, exhibited considerable binding to Bacteroidetes strains cultured from the tonsils of IgAN patients.

CONCLUSIONS

These findings provide evidence that aberrant mucosal immune responses to tonsillar anaerobic microbiota, primarily consisting of members of the phylum Bacteroidetes, are involved in IgAN pathophysiology.

microRNA-630 Regulates Underglycosylated IgA1 Production in the Tonsils by Targeting TLR4 in IgA Nephropathy

IgA nephropathy (IgAN) is the most common primary glomerular disease. The characteristic pathology involves immune complexes formed by the deposition of IgA1 and underglycosylated IgA1 aggregates in the mesangial area, which may be accompanied by the deposition of IgG and/or IgM and complement components. However, the molecular mechanisms of IgAN remain unclear. In the present study, microarray analysis showed that the expression of microRNA-630 (miR-630) was significantly reduced in palatal tonsils from IgAN patients compared with chronic tonsillitis. Additionally, bioinformatic analysis showed that Toll-like receptor 4 (TLR4) was the predicted target gene of miR-630 and was regulated by miR-630. When miR-630 was overexpressed in palatal tonsil mononuclear cells from IgAN patients, the expression of TLR4 was reduced and the content of IgA1 in the cell culture supernatant was decreased, and the level of galactosylation in the IgA1 hinge region was increased. Moreover, immunohistochemical analysis showed that the expression of TLR4 in IgAN patients was significantly increased. After knocking down the expression of TLR4, both the concentration of IgA1 and the binding force of IgA1 with broad bean lectin were significantly reduced in IgAN. Furthermore, the mechanism study demonstrated that TLR4 might regulate the expression of IL-1β and IL-8 through NF-κB signaling pathway to modulate the concentration of IgA1 and the glycosylation level of IgA1. This interesting finding may offer new insight into the molecular mechanism of IgAN.

Long-Term Beneficial Effects of Tonsillectomy on Patients with Immunoglobulin A Nephropathy

BACKGROUND

Tonsillectomy may treat IgA nephropathy (IgAN) by reducing the levels of galactose-deficient IgA1. Therefore, we aimed to analyze the long-term effects of tonsillectomy on patients with IgAN, as an initial treatment and as a treatment at any time in their lives.

METHODS

In this retrospective cohort analysis, 1147 patients with IgAN were grouped according to whether they had undergone tonsillectomy at any time, >1 year after renal biopsy (study 1), or within 1 year after renal biopsy (study 2). The patients were propensity-score matched or divided into four groups according to their proteinuria and renal function. The 20-year renal survival rates were evaluated until serum creatinine levels doubled (primary end point) and ESKD occurred (secondary end point).

RESULTS

Patients in both studies had similar background characteristics after propensity score matching. In study 1, the renal survival rates for the primary and secondary end points were significantly higher for patients who underwent tonsillectomy at any time or >1 year after renal biopsy compared with those who did not. In study 2, the renal survival rates for the primary and secondary end points were significantly higher for patients who underwent tonsillectomy soon after renal biopsy compared with those who did not (primary end point, 98% versus 69%, P=0.001; secondary end point, 100% versus 75%, P=0.0001). A stratified analysis showed that significant treatment efficacy was observed for patients with proteinuria >1.0 g/d. Multivariate Cox regression analyses showed that tonsillectomy was associated with disease progression (hazard ratio, 0.27; P=0.04). Complications associated with tonsillectomy occurred in 8% of patients.

CONCLUSIONS

Among patients with IgAN, tonsillectomy at any time of life, or soon after renal biopsy, prevents disease progression, and the procedure is relatively safe.

Association Between Galactose-Deficient IgA1 Derived From the Tonsils and Recurrence of IgA Nephropathy in Patients Who Underwent Kidney Transplantation

Background: Recurrence of IgA nephropathy (IgAN) in the transplanted kidney is associated with graft survival, but no specific treatment is available. Tonsillectomy (TE) reportedly arrests the progression of IgAN in the native kidney. Thus, we conducted a single-center retrospective cohort study to evaluate the effect of TE prior to IgAN recurrence.

Methods: Of the 36 patients with biopsy-proven IgAN who underwent kidney transplantation, 27 were included in this study. Nine patients underwent TE at 1 year after kidney transplantation (group 1), and the remaining 18 did not undergo TE (group 2).

Results: The rate of histological IgAN recurrence was significantly lower in group 1 than in group 2 (11.1 vs. 55.6%, log-rank p = 0.046). In addition, half of the recurrent patients in group 2 exhibited active lesions, compared to none in group 1. Serum Gd-IgA1 levels decreased after TE in group 1, whereas they remained stable or increased slightly in group 2. In the recurrent cases, IgA and Gd-IgA1 were found in the germinal center in addition to the mantle zone of tonsils. Finally, mesangial IgA and Gd-IgA1 immunoreactivity was reduced after TE in some cases.

Conclusion: Our data suggest that TE at 1 year after kidney transplantation might be associated with the reduced rate of histological IgAN recurrence. TE arrested or reduced serum Gd-IgA1 and mesangial Gd-IgA1 immunoreactivity. Therefore, we generated a hypothesis that serum Gd-IgA1 derived from the tonsils may play a pivotal role in the pathogenesis of IgAN. Based on these findings, we need to conduct verification in a prospective randomized controlled trial.

Tonsillectomy Monotherapy for IgA Nephropathy: A Case Series

Rationale & Objective

Studies of immunoglobulin A nephropathy (IgAN) have suggested the therapeutic benefit of simultaneously adding tonsillectomy to corticosteroid therapy. However, the efficacy of tonsillectomy monotherapy in the absence of simultaneous use of corticosteroids is unclear.

Study Design

Patients with IgAN treated with tonsillectomy monotherapy were analyzed retrospectively. Clinical parameters, including kidney function slope, were compared before and after tonsillectomy.

Setting & Participants

Patients with biopsy-proven IgAN who received tonsillectomy monotherapy at our hospital between 2007 and 2018.

Results

20 Japanese patients with IgAN were included in this study (mean follow-up period, 135 months from initial biopsy diagnosis to tonsillectomy). All patients had been treated with renin-angiotensin-aldosterone system inhibitors. 17 patients had a history of induction therapy with corticosteroids. Mean time to tonsillectomy from termination of corticosteroid therapy was 84 months. Hematuria, proteinuria, and clinical remission were achieved in 13 of 17 (76%), 10 of 17 (59%), and 8 of 20 (40%) patients at medians of 3.0, 6.0, and 13.5 months, respectively, after tonsillectomy. The slope of the estimated glomerular filtration rate (eGFR) increased significantly during the 81-month observation period, including the periods before and after tonsillectomy (−2.59 vs 1.05 mL/min/1.73 m² per year; P < 0.001). The effect on eGFR slope was consistent in 11 patients with reduced GFR (eGFR < 60 mL/min/1.73 m²) at the time of tonsillectomy (−3.07 vs −0.39 mL/min/1.73 m² per year; P < 0.001).

Limitations

Small sample size. Lack of a control (no-tonsillectomy) group due to the difficulty of setting the baseline time point (which corresponded to tonsillectomy in our sample). Potential exclusion of patients with the most severe disease who are likely to receive corticosteroids. Lack of generalizability to patients in other countries.

Conclusions

Tonsillectomy monotherapy may prevent kidney function decline in some patients with IgAN with kidney disease that has been progressive despite long-term application of conventional therapies.

Analysis of microbial changes in the tonsillar formalin-fixed paraffin-embedded tissue of Chinese patients with IgA nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is a prevalent chronic glomerular disease contribution to end-stage renal failure (ESRD). The tonsillar microbiota is closely associated with IgAN diseases based on the mucosal immune response. However, the composition and function of in tonsillar microbiota in participant patients with IgAN remains unknown. In this study, we detected the tonsillar microbiota changes of IgAN patients in Heilongjiang province located in northeast China.

MATERIAL AND METHODS

We collected from 21 patients with IgAN and 16 patients with chronic tonsillitis (CT) who had undergone tonsillectomy previously. Histological review of all samples from formalin-fixed paraffin-embedded (FFPE) tissue were performed. Extracted DNA from FFPE tissue blocks, after that V4 regions of 16S ribosomal RNA (rRNA) sequencing and comparative analyses of tonsillar flora between two groups were performed. The statistical analysis used the SPSS version of 21.

RESULTS

Visualization of microorganisms by Gram and Warthin-Starry (WS) silver stains, preliminarily observed the morphological characteristics of microbiome in FFPE tissue cases, such as bacteria or fungi. Tonsillar FFPE samples from the IgAN patients and CT controls showed significant differences in tonsillar microbial certain compositions and functions. We found that there were eight dominant genera that can be available to distinguish IgAN patients from CT controls. Compared with CT controls, at genus level, the relative abundances of Methylocaldum and unclassified_f_Prevotellaceae were significantly higher, while the abundances of Anaerosphaera, Halomonas, Trichococcus, Peptostreptococcus, norank_f_Synergistaceae and unclassified_k_norank_d_Bacteria were significantly lower in IgAN patients. Principal co-ordinates analysis (PCOA) distinguished IgAN patients from CT controls, and receiver operating characteristic (ROC) curves analysis confirmed that the diagnosis of disease has certain diagnostic significance. In addition, Functional analysis revealed that partly Enzymes and KOs were increased in the IgAN patients.

CONCLUSIONS

Histological screening results were very helpful for further gene sequencing, not only to supplement the observation of bacterial morphology and structure, but also to prepare for subsequent gene sequencing and bioinformatics analysis. We elucidated subtle relevance between changes in tonsillar microbiota and IgAN patients, which can be utilized to predict the incidence of IgAN disease. In addition, we predicted that some enzymes, and KOs were closely related to IgAN.

Renal pathological analysis using galactose-deficient IgA1-specific monoclonal antibody is a strong tool for differentiation of primary IgA nephropathy from secondary IgA nephropathy

In several cases with IgA nephropathy (IgAN), differential diagnosis is difficult due to the complication with other systemic diseases which can induce secondary IgAN. Recently, we demonstrated that immunostaining with galactose-deficient IgA1-specific monoclonal antibody (KM55 mAb) specifically showed positive in primary IgAN cases. Here, we report four cases which we could make definitive diagnosis by immunohistological analysis using KM55 mAb. The underlying systemic diseases are rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), hepatitis C (HCV) and Crohn’s disease (CD). Renal pathological findings in the four cases revealed mesangial proliferative glomerulonephritis with IgA and C3 deposits. Immunostaining with KM55 mAb was positive for three cases complicated with RA, SLE and CD, respectively. Thus, these three cases were diagnosed as primary IgAN and treated with tonsillectomy and steroid pulse therapy. These three cases finally achieved clinical remission. On the other hand, the case with HCV showed negative for KM55. Finally, we diagnosed as HCV-related nephropathy and successfully treated by antiviral agents. These cases suggested KM55 mAb is a strong tool to differentiate primary IgAN from secondary IgAN.

The analysis of treatment of Immunoglobulin A-nephropathy

Aim. An evaluation of the effectiveness of immunosuppressive therapy (IST) and tonsillectomy (TE) in patients with IgA nephropathy (IgAN). Materials and methods. A retrospective cohort of the study included cases with biopsy proven primary IgAN (n=367, age 3412 years, men 55%). We used demographic and clinical and morphological parameters at the time of biopsy. Median followup period was 26 (10; 61) months. Outcomes were remission (complete or partial) and the progression of IgAN (defined as the start of dialysis or a decrease in glomerular filtration rate 50% from baseline). All patients received treatment with renin angiotensin system blockers. Evaluation of the effectiveness of therapy was carried out using propensity score (PS) methods matching, conventional double robust regression models with PS as independent covariate, and inverse probability weighting. Following patient subgroups were used for comparative analyses: with IST (n=176) and without IST (n=191); with TE (n=63) and without TE (n=304); without IST and without TE (IST-TE-; n=162); with TE and without IST (IST-TE+; n=29); with IST and without TE (IST+TE-; n=142); with IST and with TE (IST+ TE+; n=34). Results. All PS methods used gave close estimates of the comparative effectiveness of treatment in different subgroups: 1) patients on monotherapy with corticosteroids (CS) and combination of CS with other immunosuppressants did not have significant differences in probabilities of IgAN progression (hazard ratio 0.919; 95% CI 0.3332.950) and remission (odds ratio 0.919; 95% CI 0.3792.344) and were further combined into a group of IST; 2) IST was significantly associated with the lower risk of disease progression and increased odds ratio for remission; 3) the positive effects of IST were limited to cases with proteinuria 2 g/24 h; 4) the likelihood of IgAN remission and progression did not differ significantly between TE+ and TE-, IST-TE+ and IST-TE- groups. There were no cases of disease progression in the IST+TE+ group. The cumulative renal survival was higher in the IST+TE+ group compared to IST+ TE- group (p=0.010), while the probability of remission did not differ. Conclusion. IST was associated with a lower risk of IgAN progression and increased probability of remission, while these effects of IST were limited to patients with proteinuria 2 g/24 h. TE in combination with IST is associated with an additional reduction in the risk of disease progression.

Immunosuppressive agents for treating IgA nephropathy

BACKGROUND

IgA nephropathy is the most common glomerulonephritis world-wide. IgA nephropathy causes end-stage kidney disease (ESKD) in 15% to 20% of affected patients within 10 years and in 30% to 40% of patients within 20 years from the onset of disease. This is an update of a Cochrane review first published in 2003 and updated in 2015.

OBJECTIVES

To determine the benefits and harms of immunosuppression strategies for the treatment of IgA nephropathy.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 9 September 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs of treatment for IgA nephropathy in adults and children and that compared immunosuppressive agents with placebo, no treatment, or other immunosuppressive or non-immunosuppressive agents.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study risk of bias and extracted data. Estimates of treatment effect were summarised using random effects meta-analysis. Treatment effects were expressed as relative risk (RR) and 95% confidence intervals (95% CI) for dichotomous outcomes and mean difference (MD) and 95% CI for continuous outcomes. Risks of bias were assessed using the Cochrane tool. Evidence certainty was evaluated using GRADE methodology.

MAIN RESULTS

Fifty-eight studies involving 3933 randomised participants were included. Six studies involving children were eligible. Disease characteristics (kidney function and level of proteinuria) were heterogeneous across studies. Studies evaluating steroid therapy generally included patients with protein excretion of 1 g/day or more. Risk of bias within the included studies was generally high or unclear for many of the assessed methodological domains. In patients with IgA nephropathy and proteinuria > 1 g/day, steroid therapy given for generally two to four months with a tapering course probably prevents the progression to ESKD compared to placebo or standard care (8 studies; 741 participants: RR 0.39, 95% CI 0.23 to 0.65; moderate certainty evidence). Steroid therapy may induce complete remission (4 studies, 305 participants: RR 1.76, 95% CI 1.03 to 3.01; low certainty evidence), prevent doubling of serum creatinine (SCr) (7 studies, 404 participants: RR 0.43, 95% CI 0.29 to 0.65; low certainty evidence), and may lower urinary protein excretion (10 studies, 705 participants: MD -0.58 g/24 h, 95% CI -0.84 to -0.33;low certainty evidence). Steroid therapy had uncertain effects on glomerular filtration rate (GFR), death, infection and malignancy. The risk of adverse events with steroid therapy was uncertain due to heterogeneity in the type of steroid treatment used and the rarity of events. Cytotoxic agents (azathioprine (AZA) or cyclophosphamide (CPA) alone or with concomitant steroid therapy had uncertain effects on ESKD (7 studies, 463 participants: RR 0.63, 95% CI 0.33 to 1.20; low certainty evidence), complete remission (5 studies; 381 participants: RR 1.47, 95% CI 0.94 to 2.30; very low certainty evidence), GFR (any measure), and protein excretion. Doubling of serum creatinine was not reported. Mycophenolate mofetil (MMF) had uncertain effects on the progression to ESKD, complete remission, doubling of SCr, GFR, protein excretion, infection, and malignancy. Death was not reported. Calcineurin inhibitors compared with placebo or standard care had uncertain effects on complete remission, SCr, GFR, protein excretion, infection, and malignancy. ESKD and death were not reported. Mizoribine administered with renin-angiotensin system inhibitor treatment had uncertain effects on progression to ESKD, complete remission, GFR, protein excretion, infection, and malignancy. Death and SCr were not reported. Leflunomide followed by a tapering course with oral prednisone compared to prednisone had uncertain effects on the progression to ESKD, complete remission, doubling of SCr, GFR, protein excretion, and infection. Death and malignancy were not reported. Effects of other immunosuppressive regimens (including steroid plus non-immunosuppressive agents or mTOR inhibitors) were inconclusive primarily due to insufficient data from the individual studies in low or very low certainty evidence. The effects of treatments on death, malignancy, reduction in GFR at least of 25% and adverse events were very uncertain. Subgroup analyses to determine the impact of specific patient characteristics such as ethnicity or disease severity on treatment effectiveness were not possible.

AUTHORS' CONCLUSIONS

In moderate certainty evidence, corticosteroid therapy probably prevents decline in GFR or doubling of SCr in adults and children with IgA nephropathy and proteinuria. Evidence for treatment effects of immunosuppressive agents on death, infection, and malignancy is generally sparse or low-quality. Steroid therapy has uncertain adverse effects due to a paucity of studies. Available studies are few, small, have high risk of bias and generally do not systematically identify treatment-related harms. Subgroup analyses to identify specific patient characteristics that might predict better response to therapy were not possible due to a lack of studies. There is no evidence that other immunosuppressive agents including CPA, AZA, or MMF improve clinical outcomes in IgA nephropathy.

Specific strains of Streptococcus mutans, a pathogen of dental caries, in the tonsils, are associated with IgA nephropathy

Streptococcus mutans is known to be a major causative agent of dental caries, and strains expressing the cell surface collagen-binding Cnm protein contribute to the development of several systemic diseases. A relationship between tonsillar immunity and glomerulonephritis has been recognized in IgA nephropathy (IgAN), and specific pathogens may have effects on tonsillar immunity (mucosal immunity). Here, we present findings showing a relationship between the presence of Cnm-positive S. mutans strains in the tonsils of IgAN patients and IgAN condition/pathogenesis. Analyses of tonsillar specimens obtained from patients with IgAN (n = 61) and chronic tonsillitis (controls; n = 40) showed that the Cnm protein-positive rate was significantly higher in IgAN patients. Among IgAN patients, the tonsillar Cnm-positive group (n = 15) had a significantly higher proportion of patients with high urinary protein (>1.5 g/gCr) and lower serum albumin level than the Cnm-negative group (n = 46). Additionally, Cnm protein and CD68, a common human macrophage marker, were shown to be merged in the tonsils of IgAN patients. These findings suggest that Cnm-positive S. mutans strains in the tonsils may be associated with severe IgAN.