BACKGROUND Eosinophils in kidney disease are poorly understood and are often incidental findings on kidney biopsy. Eosinophilia in blood and renal biopsy tissue is associated with a host of immune and non-immune kidney diseases. The significance of eosinophilia in renal diseases has not been well addressed. We evaluated the presence of peripheral eosinophilia (> 4% of blood leukocytes) with biopsy tissue eosinophilia and their association with end-stage-kidney-disease (ESKD). METHODS A nested case-control (2:1) of patients who underwent kidney biopsies at Johns Hopkins Hospital and Medical University of South Carolina from 2004 to 2018 were included in the study. From the 616 eligible patients, 178 patients were identified through the registry of kidney biopsies as 18 years or older without missing biopsy reports or hematology results. Controls (n = 154) had no ESKD at the time of case (n = 24) designation and were assembled using incident density sampling and matched on age and sex. The association of peripheral eosinophilia (> 4% of peripheral blood leukocytes) with the risk of progression to ESKD was evaluated using conditional logistic model after adjusting for clinical demographics. RESULTS Among 178 patients, 65 (37%) had peripheral eosinophilia and 113 (63%) had no eosinophilia. Compared to patients without eosinophilia, patients with peripheral eosinophilia were notably male and had a higher serum creatinine at the time of their biopsy. Peripheral eosinophilia was associated with higher risk of ESKD (OR 15.9 [1.9, 134.7]) adjusted for patient demographics including hypertension, proteinuria and eGFR at the time of kidney biopsy. Peripheral eosinophilia had a significant linear association with kidney tissue eosinophils, 22 (standard deviation [SD] 20) per high power field (hpf) in 4-10% peripheral eosinophilia, 19 (SD 18) per hpf in ≥10% eosinophilia and 3 (SD 7) per hpf in no eosinophilia (P <  0.001). CONCLUSIONS Peripheral eosinophilia is an independent predictor of tissue eosinophilia and subsequent progression to ESKD. Peripheral eosinophilia may be an early biomarker for underlying inflammation and disease, but further studies to investigate this clinical association are warranted.

中文翻译：

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嗜酸性粒细胞增多和发生终末期肾病的风险。

背景人们对肾脏疾病中的嗜酸性粒细胞知之甚少，并且常常是肾活检中偶然发现的。血液和肾活检组织中的嗜酸性粒细胞增多与许多免疫和非免疫肾脏疾病有关。嗜酸性粒细胞增多在肾脏疾病中的重要性尚未得到很好的解决。我们通过活检组织嗜酸性粒细胞增多评估了外周血嗜酸性粒细胞增多（> 4% 的血液白细胞）及其与终末期肾脏病 (ESKD) 的关联。方法 本研究纳入了 2004 年至 2018 年在约翰·霍普金斯医院和南卡罗来纳医科大学接受肾活检的患者的巢式病例对照 (2:1)。在 616 名符合条件的患者中，通过肾活检登记，确定了 178 名患者年龄为 18 岁或以上，且没有遗漏活检报告或血液学结果。对照组 (n = 154) 在病例 (n = 24) 指定时没有 ESKD，并使用事件密度抽样进行组装，并在年龄和性别上进行匹配。在调整临床人口统计数据后，使用条件逻辑模型评估外周血嗜酸性粒细胞增多（外周血白细胞> 4%）与进展为 ESKD 风险的关联。结果 178 例患者中，65 例（37%）有外周血嗜酸粒细胞增多，113 例（63%）无嗜酸粒细胞增多。与无嗜酸粒细胞增多的患者相比，外周血嗜酸粒细胞增多的患者主要为男性，并且在活检时血清肌酐较高。外周血嗜酸性粒细胞增多与较高的 ESKD 风险相关（OR 15.9 [1.9, 134.7]），根据患者人口统计数据（包括肾活检时的高血压、蛋白尿和 eGFR）进行调整。外周嗜酸粒细胞增多与肾组织嗜酸粒细胞呈显着线性相关，4-10% 外周嗜酸粒细胞增多时，每高倍视野 (hpf) 22 个（标准差 [SD] 20）；≥10% 嗜酸粒细胞增多时，每 hpf 19 个（标准差 [SD] 18）；3 (SD 7) 每 hpf 无嗜酸性粒细胞增多 (P < 0.001)。结论 外周嗜酸性粒细胞增多是组织嗜酸性粒细胞增多和随后进展为 ESKD 的独立预测因素。外周嗜酸性粒细胞增多可能是潜在炎症和疾病的早期生物标志物，但需要进一步研究来调查这种临床关联。