Implications of immunoglobulin G deposit in glomeruli in Chinese patients with diabetic nephropathy

In the current study, we explored the associations of glomerular immunoglobulin G (IgG) deposit and further investigated the pattern of IgG subclass deposition in the renal biopsy specimens from patients with diabetic nephropathy (DN).

A total of 170 inpatients with type 2 diabetes mellitus and biopsy-proven DN who were followed up for at least 1 year were retrospectively recruited. Renal outcomes were defined by DN progression (end-stage renal disease [ESRD] or ≥ 50% reduction in estimated glomerular filtration rate [eGFR] from baseline). Additionally, 38 renal biopsy specimens of patients with renal IgG deposit underwent the immunofluorescence IgG1-4 staining.

The median follow-up period was 22 months. During follow-up, 38.23% (65) of patients progressed to ESRD, and 6.47% (11) of patients had an eGFR decline ≥50%. The multivariate Cox analysis demonstrated that the glomerular IgG deposit (hazard ratio, 1.835; 95% CI, 1.013-3.324, P = .045) was still significantly associated with DN progression when adjusted for the important clinical variables and pathological findings. In addition, a logistic regression showed that the glomerular IgG deposit was independently associated with glomerular basement membrane (GBM) thickness (odds ratio [OR], 1.276; 95% CI, 1.046-1.558; P = .016), Kimmelstiel-Wilson nodules formation (OR, 3.822; 95% CI, 1.052-13.881; P = .042), and C3 deposit in the glomeruli (OR, 124.883; 95% CI, 20.754-751.472; P < .001). The IgG subclass staining showed that IgG1 deposit along the GBM tended to be dominant (28/38) in IgG (+) patients with DN.

The glomerular IgG deposit affected glomerular structure and emerged as an independent risk factor for the renal clinical outcomes. In addition, IgG1 predominantly deposited along the GBM among the DN patients with IgG (+), which might be involved in the renal injury and progression of DN.