Study of tonsillectomy for IgA nephropathy patients: short- and longer-term observation

Interaction between Ras and Bcl2L12 in B cells suppresses IL-10 expression

The pathogenesis of recurrent tonsillitis is to be further investigated. B cell-derived interleukin (IL)-10 plays a critical role in immune regulation. Ras activation plays an important role in cancer and many immune disorders. This study aims to investigate the role of Ras activation in down regulating IL-10 expression in tonsillar B cells. Surgically removed tonsil tissues were collected from patients with recurrent acute tonsillar inflammation; B cells were isolated from the tonsillar tissues by flow cytometry sorting to be analyzed by the Ras-specific enzyme-linked immunosorbent assay and pertinent immunological approaches. We found that, compared to peripheral B cells (pBC), B cells isolated from the tonsillar tissues with recurrent inflammation (tBC) showed higher Ras activation, lower IL-10 expression and higher Bcl2L12 expression. Bcl2L12 formed a complex with GAP (GTPase activating protein) to prevent Ras from deactivating. The Ras activation triggered the MAPK/Sp1 pathway to promote the Bcl2L12 expression in B cells. Bcl2L12 prevented the IL-10 expression in tBCs, that was counteracted by inhibition of Ras or the Ras signal transduction pathway. In conclusion, Bcl2L12 interacts with Ras activation to compromise immune tolerance in the tonsils by inhibiting the IL-10 expression in tBCs. Inhibition of Bcl2L12 can restore the IL-10 expression in tBCs.

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.

Impact of the number of steroid pulses in tonsillectomy combined with steroid pulse therapy: a nationwide retrospective study in Japan

BACKGROUND

Steroid pulse therapy with tonsillectomy is known as a major treatment for IgA nephropathy (IgAN). However, its protocol was different among institutions and the effects of varying the number of steroid pulses remain unclear.

METHODS

From a total of 1,174 IgAN patients in a multicenter retrospective cohort analysis in Japan, 195 patients were treated by tonsillectomy combined with corticosteroid. They were divided into four groups based on the number of administered steroid pulses from 0 to three (TSP0-3), and remission of urinary abnormalities and renal survival until 1.5-fold increase in serum creatinine level from baseline were analyzed among the four groups and between TSP1 and TSP3.

RESULTS

Among the four groups, renal function was relatively good when the estimated glomerular filtration rate was approximately 80-90 mL/min/1.73m² and proteinuria was relatively mild (< 1.0 g/gCre). The ratio of patients who developed renal dysfunction was < 5% in all groups, and the cumulative renal survival rate by Kaplan-Meier analysis was similar among groups (log-rank test, p = 0.37), despite varying clinical backgrounds and treatments. After adjustment of the background variables between TSP1 and TSP3, the remission rates of urinary abnormalities were similar and the renal survival rate also remained similar (66.8 vs. 85.4%, p = 0.45).

CONCLUSIONS

In patients with mild proteinuria and good renal function, the number of steroid pulses did not affect the renal outcome in steroid pulse therapy with tonsillectomy. The adaptation and protocols, such as the number of steroid pulses, should be determined for each IgAN patient's background.

The efficacy of tonsillectomy on clinical remission and relapse in patients with IgA nephropathy: a randomized controlled trial

BACKGROUND

The efficacy of tonsillectomy in immunoglobulin A nephropathy (IgAN) remains controversial. The aim of the study was to conduct a randomized controlled trial to evaluate the effect of tonsillectomy in patients with IgAN.

METHODS

We randomly selected 98 patients with biopsy-proven IgA nephropathy and randomly allocated to receive tonsillectomy combined with drug therapy (Group A) or drug therapy alone (Group B). The participating patients were entered into a 4-year single-center study. Remission and relapse rate were calculated for hematuria and proteinuria using the Kaplan-Meier method.

RESULTS

No differences were found between the two groups in their baseline clinical and histological characteristics. Patients with tonsillectomy exhibited considerable improvement in the following aspects compared to those patients who did not undergo tonsillectomy: time to reach first remission (3.1 vs. 24.9 months, p < 0.001) for hematuria and (2.5 vs. 26.1 months, p < 0.001) for proteinuria, cumulative remission rate (91.8% vs. 46.9%, p < 0.001 by log-rank test) for hematuria and (95.9% vs. 51.0%, p < 0.001) for proteinuria, the duration of first remission (26.5 vs. 11.8 months, p = 0.0047) for hematuria and (23.5 vs. 10.5 months, p = 0.0012) for proteinuria, as well as lower relapse rate for hematuria and proteinuria in Group A.

CONCLUSION

Our clinical data demonstrated that tonsillectomy could be beneficial for IgAN patients, particularly by contributing to faster and longer remission, as well as reducing the frequency of possible future relapses.

Decreased expression of follicular dendritic cell-secreted protein correlates with increased immunoglobulin A production in the tonsils of individuals with immunoglobulin A nephropathy

Immunoglobulin A nephropathy (IgAN) is characterized by a qualitative abnormality of IgA in the circulation and IgA deposition in the renal mesangium. Recent research has indicated that pathogenic IgA may originate from affected tonsils. Follicular dendritic cell-secreted protein (FDC-SP), a small novel secretory protein that may regulate the induction of B-cell responses, has been suggested to control IgA production. Given this background, this study investigated the expression of FDC-SP and its correlation with IgA production in the tonsils of IgAN patients. Immunohistochemistry and reverse transcription-polymerase chain reaction were used to compare the expression of FDC-SP in the tonsils of IgAN patients with tonsillitis and of non-IgAN patients with chronic tonsillitis. The location of FDC-SP in tonsillar tissue was confirmed by double immunofluorescence. We found that FDC-SP expression significantly decreased and was correlated negatively with enhanced IgA production in the tonsils of IgAN patients. FDC-SP secreted by follicular dendritic cells may act on germinal center B cells and participate in the modulation of IgA generation in the tonsils. Our study demonstrated that FDC-SP may be involved in IgA production in the tonsils of IgAN patients, making this protein an attractive candidate immunomodulator, and highlighting a promising strategy for therapeutic intervention in IgAN.

Characteristics of IgA nephropathy in advanced-age patients

PURPOSE

The susceptible age for IgA nephropathy (IgAN) is <30 years. However, IgAN sometimes develops in people aged >60 years, and its characteristics remain unknown.

METHODS

We divided 600 IgAN patients into three groups: advanced-age group (AAG, n=31, ≥60 years); middle-aged group (MAG, n=162, 40-59 years); and young-aged group (YAG, n=407, 20-39 years). We analyzed clinical and histological background, renal outcome, and risk of progression.

RESULTS

In the AAG, mean arterial pressure (MAP) and the number of hypertensive patients were significantly higher than in the YAG. Total protein, serum albumin, and estimated glomerular filtration rate were significantly lower, and blood urea nitrogen, proteinuria, and N-acetyl-β-D-glucosaminidase were significantly higher in the AAG than in MAG and YAG. In histological findings, interstitial fibrosis/tubular atrophy by Oxford classification and arteriosclerosis were more severe in the AAG than the in YAG. Renal survival rate analyzed by Kaplan-Meier method was significantly lower in the AAG (22.9%/19 years in the AAG vs. 69.2 and 84.9%/20 years in the MAG and YAG, p<0.0001). The patients who progressed to end-stage renal disease (ESRD) in the AAG had higher MAP and more severe proteinuria compared with the patients who did not progress to ESRD in the AAG.

CONCLUSIONS

The characteristics of IgAN in advanced-age were lower renal function, high levels of proteinuria, severe interstitial change, and arteriolosclerosis caused by glomerulopathy and concomitant diseases, such as hypertension, dyslipidemia, and hyperuricemia. Prognosis was poor, and >70% developed ESRD within 20 years.