#3655 Eosinophilic infiltration in biopsies of patients with diabetic nephropathy

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Abstract Background and Aims Eosinophilic infiltration has been studied as a potential prognostic factor for renal survival in patients with diabetic nephropathy. The aim of this study is to describe the clinical and histological characteristics of diabetic patients based on the presence of eosinophils. Method Retrospective observational study including patients with diabetes who underwent a kidney biopsy between April 2017 and July 2022. Clinical, analytical, and histological variables were collected. Statistical analysis was performed using SPSS version 25. Results Twenty-three patients were included, with 18 men (78.3%) and a mean age of 60.0±10.0 years. Most patients had type 2 diabetes (22, 95.7%), with a median time since diagnosis of 2.7 years (IQR 1.4–16.0). The majority (16, 69.6%) were receiving insulin. The median glycated hemoglobin was 6.6% (IQR 5.9–8.3). Four patients (17.4%) had started renal replacement therapy at the time of the renal biopsy. The main indications for biopsy were worsening of renal function (12, 52.2%), nephrotic range proteinuria (6, 26.1%) and complete nephrotic syndrome (5, 21.7%). The Tervaert class of diabetic nephropathy was: class I, 1 (4.3%); IIa, 3 (13.0%); IIb, 2 (8.7%); III, 10 (43.5%); and IV, 7 (30.4%). Nine patients (39.1%) had an additional histological diagnosis to diabetes, being the most frequent one immunoallergic interstitial nephritis (3, 13.0%), followed by focal segmental glomerulosclerosis (2, 8.7%), IgA nephropathy (1, 4.3%) endocapillary glomerulonephritis (1, 4.3%), extracapillary glomerulonephritis (1, 4.3%), and thrombotic microangiopathy (1, 4.3%). In 9 biopsies (39.13%) eosinophils were found, with a median of 0.3 (IQR 0.2–0.4) eosinophils/mm2. Eosinophilic interstitial infiltration was associated with the number of sclerosed glomeruli (r = 0.590, P < 0.05), tubular atrophy (r = 0.500, P < 0.05), and interstitial inflammation (r = 0.563, P < 0.05). Patients with eosinophils in the biopsy were younger (56.0 vs. 62.0 years), had a longer time since diabetes diagnosis (16.0 vs. 11.0 years) and a lower glomerular filtration rate (36.4 ± 15.0 vs. 43.4 ± 19.0 mL/min), although these differences did not reach statistical significance. The presence of eosinophils was not predictive of renal function loss or mortality. The sample size may be a limitation for the interpretation of these results. Conclusion Eosinophilic infiltration in renal biopsies of patients with diabetic kidney disease correlates with the number of sclerosed glomeruli and with greater inflammation and tubular atrophy, possibly related to more chronic damage. The prognostic clinical implication of this finding is still unclear and further studies are needed.

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