Beneficial Effects of Tonsillectomy for Mesangial Immunoglobulin A (IgA) Deposition and Clinical Outcome in Five Kidney Transplant Patients With Recurrent IgA Nephropathy: Case Report

Post-transplant immunoglobulin A deposition and nephropathy in allografts

Post-transplant immunoglobulin A (IgA) nephropathy (IgAN) in the allograft is the major cause of allograft loss. Using a protocol biopsy, latent mesangial IgA deposition (IgAD) can be detected in the allograft. Latent IgAD is distinguished from IgAN by the absence of urinary abnormalities, although IgA is observed in the mesangium. However, the pathophysiology and most appropriate treatment strategy for latent mesangial IgAD in the allograft remain to be fully determined. Importantly, it is unknown whether all cases of post-transplant asymptomatic IgAD progress to symptomatic IgAN; indeed, IgA deposits disappear in some cases. The differences in allograft prognosis between asymptomatic IgAD and IgAN have also not been determined. Non-invasive methods of diagnosis of IgAD in the allograft using serological and pathological biomarkers are being developed. Possible serum biomarkers include serum galactose-deficient IgA1 (Gd-IgA1), Gd-IgA1-specific IgG and Gd-IgA1-specific IgA, and its immune complexes. Immunofluorescence analysis using Gd-IgA1 monoclonal antibody may provide a pathological biomarker. These serological and pathological biomarkers may be suitable for the characterization of the stage of IgAD. However, there is insufficient information regarding whether serological and pathological biomarkers can predict the progression of asymptomatic IgAD to symptomatic IgAN. We propose that the pathogenesis of IgAN can be defined through the clinical study of IgAD in the allograft using protocol biopsies conducted by nephrologists involved in clinical kidney transplantation.

Effect of steroid pulse therapy on post-transplant immunoglobulin A nephropathy

AIM

Recent studies have suggested that patients with post-transplant immunoglobulin A nephropathy have poor graft survival. There is limited research on the therapeutic effectiveness for post-transplant immunoglobulin A nephropathy, especially steroid pulse therapy. The present study evaluated the efficacy of steroid pulse therapy on post-transplant immunoglobulin A nephropathy.

METHODS

We retrospectively analyzed patients diagnosed with de novo or recurrent immunoglobulin A nephropathy at Kyushu University Hospital between January 2013 and August 2015. Patients with moderate proteinuria (≥0.5 g/g creatinine) and/or cellular or fibrocellular crescents on a graft biopsy were treated with steroid pulse therapy. Steroid pulse therapy was 500 mg/day for 3 days in weeks 1 and 2, followed by 20 mg of oral prednisolone that was tapered after 6 months. Patients were followed for 2 years, and the estimated glomerular filtration rate, urinary findings, and adverse events were recorded.

RESULTS

Seven patients received steroid pulse therapy. The mean duration after kidney transplantation was 6.6 ± 4.7 years. After 2 years of treatment, 85.7% of patients reached complete remission of proteinuria, urinary protein excretion declined (0.82 ± 0.51 to 0.26 ± 0.22 g/g creatinine, P = 0.007), and the estimated glomerular filtration rate was maintained (48.7 ± 12.8 to 47.4 ± 14.0 mL/min per 1.73 m² , P = 0.98). Adverse events were observed in one patient who developed herpes zoster infection.

CONCLUSION

Steroid pulse therapy for post-transplant immunoglobulin A nephropathy effectively reduces proteinuria over 2 years. However, comparison of steroid pulse therapy and other regimens with a high-quality design is required.

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.