Single-cell RNA Sequencing (scRNA-seq) to Investigate the Mechanisms Underlying the Induction of Regulatory T Cells in Patients With Extramembranous Glomerulonephritis Treated With Rituximab

A Study Using Single-cell RNA Sequencing (scRNA-seq) to Investigate the Mechanisms Underlying the Induction of Regulatory T Cells in Patients With Extramembranous Glomerulonephritis Treated With Rituximab

Membranous nephropathy is a rare autoimmune kidney disease in which autoantibodies, most commonly anti-PLA2R1 antibodies, target podocyte antigens and may cause nephrotic syndrome. Rituximab is used in routine care to deplete B cells and reduce pathogenic autoantibodies, but its effects are not limited to B-cell depletion. Previous work suggests that rituximab may also promote regulatory T-cell (Treg) responses, and higher Treg levels after treatment have been associated with clinical remission.

TRANSCRIPT is a prospective, single-center, pilot mechanistic study in 12 adult patients with active anti-PLA2R1-positive membranous nephropathy who have an indication for rituximab as part of routine care. Participants will receive rituximab according to usual clinical practice (1 g on Day 0 and 1 g on Day 15). Additional blood samples will be collected at Day 0 and Month 6 to isolate peripheral immune cells. Single-cell RNA sequencing will be used to identify transcriptional changes, signaling pathways, and intercellular communication networks associated with rituximab-induced Treg induction. In vitro assays will then test modulators of the candidate pathways identified by sequencing.

The study hypothesis is that rituximab modulates immune-cell signaling and communication pathways that contribute to the induction of regulatory T cells in patients with membranous nephropathy.

Inclusion Criteria:

1. Signed informed consent.
2. Anti-PLA2R1-positive membranous nephropathy.
3. Active nephrotic syndrome, defined as urinary protein/creatinine ratio >3.5 g/g and serum albumin <30 g/L.
4. Indication for rituximab treatment as part of routine care.
5. Estimated glomerular filtration rate calculated using the CKD-EPI equation >30 mL/min/1.73 m2.

Exclusion Criteria:

1. Lack of affiliation to the French social security system.
2. Vulnerable person, including minors, adults under guardianship or curatorship, pregnant women, persons deprived of liberty, or persons who do not master the French language.
3. Immunosuppressive treatment received within the previous 6 months.
4. Breastfeeding.
5. Absence of effective contraception, when applicable.
6. Premature discontinuation before administration of both rituximab infusions.
7. Voluntary withdrawal of informed consent or objection to the use of study data or biological samples.