Interstitial eosinophilic infiltration in diabetic nephropathy is indicative of poor prognosis, with no therapy benefit from steroid

BACKGROUND

Studies suggested that eosinophils in diabetes might be associated with severity of diabetic nephropathy (DN). In a retrospective study of 102 Chinese patients with biopsy-proven DN, we aimed to evaluate relationships of both blood and renal eosinophils (Eos) to the severity of DN and check whether Eos can serve as an indicator of prognosis as well as the therapeutic effect of steroids.

METHODS

One hundred and two patients diagnosed with DN were enrolled. Demographical and clinical data and histopathological scores were associated. Interstitial eosinophilic aggregates (IEA) were defined as the presence of ≥10 Eos in at least one high-power field. End-stage renal disease was defined as the end point.

RESULTS

We observed that log₂ (blood eosinophil counts) correlated with neutrophil counts, proteinuria, and tubulointerstitial inflammatory cell infiltration. IEA was observed in 33.3% of the DN patients and was associated with decreased estimated glomerular filtration rate, higher proteinuria, hematuria, higher HbA1c, increased blood eosinophil counts, tubular injury, tubulointerstitial chronicity, and interstitial inflammation. IEA was associated with worse renal prognosis (hazard ratio [HR] 2.424, P = 0.008). Consistently, urine eosinophil cationic protein (ECP) (ng/mgCr) was associated with renal injury and poor renal prognosis (HR 1.173, P = 0.020). Patients with IEA were more likely to be treated with steroid/immunosuppressants (47.1% vs 14.7%, P = 0.001) but did not show renal benefit.

CONCLUSIONS

It suggested that both blood and renal infiltrated eosinophils were prevalent in DN and associated with severity of DN. IEA in renal pathology showed better fit in correlation with renal prognosis. Treatment with steroid/immunosuppressants showed no significant improvement regarding renal prognosis.