Association of non-methane volatile organic compound emission burden with chronic kidney disease: integrated epidemiological, transcriptomic and in vitro analyses

Environmental exposure to non-methane volatile organic compounds (NMVOCs) may contribute to chronic kidney disease (CKD), but the underlying molecular pathways remain unclear. We integrated epidemiological, transcriptomic, single-cell, and experimental analyses to identify candidate mechanisms linking NMVOCs to kidney injury. Province-level NMVOC emission burden was linked to residential province for 3,472 participants in the China Health and Retirement Longitudinal Study (CHARLS). CKD was defined as an eGFR <60 mL/min/1.73 m2. Associations were evaluated using multivariable logistic regression. Putative NMVOC-CKD targets, kidney transcriptomic datasets, 113 machine-learning models, and SHapley Additive exPlanations (SHAP) were used to prioritize biomarkers. Single-cell transcriptomics, cell-communication analysis, virtual knockout, and hydroquinone-treated cell experiments were used to investigate candidate pathways. Among 3,472 participants, 417 had CKD. In the fully adjusted model, higher province-level NMVOC emission burden was associated with greater odds of prevalent CKD (OR = 1.05). The best transcriptomic classifier achieved areas under the curve of 0.964 and 0.836 in the training and validation sets. Integrated analyses prioritized SLC9A3 and localized its expression to proximal tubular cells. Single-cell analysis predicted SPP1-ITGAV/ITGB1 signaling between proximal tubular cells and fibroblasts. In a benzene-metabolite model, hydroquinone increased tubular SLC9A3 and SPP1 expression; conditioned medium increased fibroblast ITGB1 and α-smooth muscle actin expression and migration. Province-level NMVOC emission burden was associated with CKD. The findings nominate proximal-tubule SLC9A3/SPP1-integrin signaling as a candidate link between NMVOC emission burden and fibroblast activation, warranting validation through individual-level exposure assessment and targeted perturbation studies.