Immunosuppressive therapy versus supportive care in IgA nephropathy patients with stage 3 and 4 chronic kidney disease

Prognostic role of mesangial IgM deposition in IgA nephropathy: a long-term cohort study

BACKGROUND

The clinical significance of mesangial immunoglobulin (Ig) M deposition in IgA nephropathy (IgAN) has been less explored and remains a topic of debate. Therefore, our study aimed to investigate the prognostic value of mesangial IgM deposition in a long-term follow-up cohort of IgAN patients.

METHODS

A unicentric retrospective study was conducted on 93 consecutive IgAN patients (median age 41 years, 68% male, eGFR 48.7 mL/min, proteinuria 1.1 g/g) from 2010 to 2015. They were followed until end-stage kidney disease (ESKD), death, or until the end of the study in January 2021, with a median follow-up of 7 years. An independent pathologist evaluated the IgM immunofluorescence pattern, Oxford MEST-C score, and transmission electron microscopy (TEM) lesions following a comprehensive protocol.

RESULTS

In our cohort, 70% had mesangial IgM-positive deposits, while 30% were IgM-negative. Both groups were similar in age, sex, prevalence of arterial hypertension, Charlson comorbidity scores, kidney function (eGFR and proteinuria), pathology findings (Oxford MEST-C score, IgG and C3 immune deposition), and TEM analysis. Treatment with RASI and immunosuppression, and death rates were also comparable. However, 37% of IgM-positive patients progressed to ESKD, significantly higher than the 11% in the IgM-negative group. Univariate and multivariate Cox proportional hazards regression analyses identified lower eGFR, higher Oxford MEST-C score, and mesangial IgM deposits as independent factors associated with shorter kidney survival.

CONCLUSIONS

Our study highlights mesangial IgM deposition as a potential risk factor for ESKD in patients with advanced IgAN, laying a foundation for further research in this area.

A closer look: ultrastructural evaluation of high-risk progression IgA nephropathy

This retrospective, cross-sectional study sought to examine the ultrastructural characteristics of glomerular lesions using Transmission Electron Microscopy (TEM) in IgA nephropathy (IgAN) and their relationship with the high risk of progression phenotype defined by KDIGO guideline as proteinuria ≥1 g/24 hours despite 3 months of optimized supportive care. We analyzed 81 IgAN patients (median age 41 years, 67% male, eGFR 43.8 mL/min, proteinuria 1.04 g/day); 42 (52%) of them had high risk of progression. There were no differences in terms of age, sex, comorbidities, eGFR, and hematuria between the two groups. High-risk patients more often had segmental glomerulosclerosis (29% vs 8%, p 0.01) in optical microscopy, while in TEM had more frequent podocyte hypertrophy (62% vs 26%, p 0.001) and podocyte foot process detachment from the glomerular basement membrane (19% vs 8%, p 0.05), more often thicker (19% vs 5%, p 0.05) and duplicated (26% vs 10%, p 0.05) glomerular basement membrane, and the presence of subendothelial and subepithelial deposits (31% vs 13%, p 0.05). However, in multivariate binary logistic regression analysis, only podocyte hypertrophy (OR 3.14; 95%CI 1.12, 8.79) was an independent risk factor for high-risk progression in IgAN. These findings highlight the importance of podocytopathy in IgAN progression.

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.