Background

Ultrafine particles, including black carbon (BC), can reach the systemic circulation and therefore may distribute to distant organs upon inhalation. The kidneys may be particularly vulnerable to the adverse effects of BC exposure due to their filtration function.

Objectives

We hypothesized that BC particles reach the kidneys via the systemic circulation, where the particles may reside in structural components of kidney tissue and impair kidney function.

Methods

In kidney biopsies from 25 transplant patients, we visualized BC particles using white light generation under femtosecond-pulsed illumination. The presence of urinary kidney injury molecule-1 (KIM-1) and cystatin c (CysC) were evaluated with ELISA. We assessed the association between internal and external exposure matrices and urinary biomarkers using Pearson correlation and linear regression models.

Results

BC particles could be identified in all biopsy samples with a geometric mean (5th, 95th percentile) of 1.80 × 10³ (3.65 × 10², 7.50 × 10³) particles/mm³ kidney tissue, predominantly observed in the interstitium (100 %) and tubules (80 %), followed by the blood vessels and capillaries (40 %), and the glomerulus (24 %). Independent from covariates and potential confounders, we found that each 10 % higher tissue BC load resulted in 8.24 % (p = 0.03) higher urinary KIM-1. In addition, residential proximity to a major road was inversely associated with urinary CysC (+10 % distance: −4.68 %; p = 0.01) and KIM-1 (+10 % distance: −3.99 %; p < 0.01). Other urinary biomarkers, e.g., the estimated glomerular filtration rate or creatinine clearance showed no significant associations.

Discussion and conclusion

Our findings that BC particles accumulate near different structural components of the kidney represent a potential mechanism explaining the detrimental effects of particle air pollution exposure on kidney function. Furthermore, urinary KIM-1 and CysC show potential as air pollution-induced kidney injury biomarkers for taking a first step in addressing the adverse effects BC might exert on kidney function.

中文翻译：

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环境黑碳到达肾脏

背景

超细颗粒，包括黑碳（BC），可以到达体循环，因此吸入后可能分布到远处的器官。由于其过滤功能，肾脏可能特别容易受到 BC 暴露的不利影响。

目标

我们假设BC颗粒通过体循环到达肾脏，颗粒可能驻留在肾组织的结构成分中并损害肾功能。

方法

在 25 名移植患者的肾脏活检中，我们在飞秒脉冲照明下使用白光生成来可视化 BC 颗粒。通过 ELISA 评估尿肾损伤分子 1 (KIM-1) 和胱抑素 c (CysC) 的存在。我们使用皮尔逊相关和线性回归模型评估了内部和外部暴露矩阵与尿液生物标志物之间的关联。

结果

在所有活检样本中均可鉴定出 BC 颗粒，其几何平均值（第 5、95 个百分位数）为 1.80 × 10 ³ (3.65 × 10 ² , 7.50 × 10 ³ ) 颗粒/mm ³肾组织，主要在间质中观察到 (100 % ）和肾小管（80%），其次是血管和毛细血管（40%），以及肾小球（24%）。独立于协变量和潜在的混杂因素，我们发现组织 BC 负荷每增加 10%，尿 KIM-1 含量就会增加 8.24% (p = 0.03)。此外，住宅靠近主要道路与尿CysC（+10%距离：-4.68%；p = 0.01）和KIM-1（+10%距离：-3.99%；p < 0.01）呈负相关。其他尿液生物标志物，例如估计的肾小球滤过率或肌酸酐清除率未显示出显着的关联。

讨论与结论

我们的研究结果是，BC颗粒在肾脏的不同结构部件附近积聚，这代表了解释颗粒空气污染暴露对肾功能的有害影响的潜在机制。此外，尿液 KIM-1 和 CysC 显示出作为空气污染引起的肾损伤生物标志物的潜力，可在解决 BC 可能对肾功能产生的不利影响方面迈出第一步。