Case Report: Telitacicept therapy for podocytic infolding glomerulopathy associated with Sjögren’s syndrome

Background Podocytic infolding glomerulopathy (PIG) is a rare ultrastructural glomerular lesion associated with systemic autoimmune disease and has no standardized treatment. Sjögren’s syndrome is characterized by B-cell hyperactivity, autoantibody production, and persistent plasma-cell survival. Telitacicept is a fusion protein that neutralizes B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL). Case presentation A 54-year-old woman presented with nephrotic syndrome, including 24-h urinary protein excretion of 14.841 g, serum albumin of 16.6 g/L, and serum creatinine of 72.3 μmol/L. Longstanding dry mouth and dry eyes, ANA 1:1,000, anti-SSA/Ro, anti-SSB/La, and anti-Ro52 positivity, elevated IgG, and exclusion of relevant alternative conditions supported a clinical diagnosis of Sjögren’s syndrome. Objective ocular and salivary-gland tests required for formal fulfillment of the 2016 ACR/EULAR classification criteria were not performed owing to patient refusal and prioritization of renal disease management. Kidney biopsy showed mild mesangial-cell and matrix proliferation with segmental glomerular basement membrane (GBM) thickening; immunofluorescence showed trace granular IgG deposition along glomerular capillary loops, with negative C3, IgG1-4, PLA2R, and THSD7A staining. Electron microscopy demonstrated podocyte swelling, vacuolar degeneration, diffuse foot-process effacement with microvillous transformation, and multiple round membranous structures within the GBM with focal dissolution, supporting PIG. Proteinuria remained approximately 4.3-5.6 g/24 h during the 3 months immediately before telitacicept despite glucocorticoids, tacrolimus, Tripterygium wilfordii glycosides, canagliflozin, and supportive therapy. Telitacicept 160 mg once weekly was added in May 2023 and, after approximately 8 months, was empirically changed to 160 mg once monthly. Proteinuria subsequently declined into the subnephrotic range and serum albumin recovered while glucocorticoids and later tacrolimus were tapered and discontinued. At the final follow-up, proteinuria was 1.235 g/24 h, serum albumin was 38.3 g/L, and serum creatinine was 65 μmol/L. During 32 months of follow-up after telitacicept initiation, no serious infection requiring hospitalization or treatment-limiting adverse reaction was recorded. Conclusion Telitacicept initiation was temporally associated with proteinuria reduction and albumin recovery maintained during immunosuppressive de-escalation. Because of concomitant therapies and the single-case design, an independent causal effect of telitacicept cannot be established. Telitacicept may have contributed to the observed improvement, and this observation should be considered hypothesis-generating.