bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2025.08.29.673189

Evaluation of toxicological mechanisms of ochratoxin-A in human primary proximal tubule epithelial cells

Mahadeo, A.·Bammler, T. K.·MacDonald, J.·Zheng, A. R.·Yeung, C. K.·Himmelfarb, J.·Kelly, E. J.
View original source ↗Export metadata ↓

Abstract

Ochratoxin-A (OTA) is a ubiquitous mycotoxin contaminant in food products and a known nephrotoxin. OTA is hypothesized to be a potential environmental agent causing chronic kidney disease of unknown etiology (CKDu), however the mechanism of OTA toxicity in the human kidney remains elusive. This study aims to elucidate OTA-induced molecular toxicological pathways using primary human proximal tubule epithelial cells (PTECs). We demonstrated that exposure to OTA (10 M) induces over 7000 differentially expressed genes, including key regulators of mitochondrial fission and fusion. This was confirmed at the cellular level by confocal microscopy, where a breakdown of the mitochondrial network was observed at 100 nM OTA. Crucially, OTA was found to significantly induce reactive oxygen species (mROS) and inhibit basal mitochondrial oxidative phosphorylation as well as glycolysis through measurements of oxygen consumption rate and extracellular acidification, indicating reduced cellular energetics and mitochondrial toxicity. The previously reported downregulation of NRF2 target antioxidant response elements was not able to be recovered with co-administration of NRF2 agonists, sulforaphane or tert-butylhydroquinone, suggesting a possible mechanism of inhibition of NRF2 nuclear translocation or DNA binding. In conclusion, we demonstrate that OTA induces oxidative stress, mitochondrial dysfunction, and reduced ATP production, leading to a senescent-like state in PTECs characteristic of renal disease progression. These findings provide insight into early toxicological endpoints induced by OTA which have been established as pathophysiological changes involved in chronic kidney disease. HighlightsO_LIOTA exposure suppresses oxidative phosphorylation and glycolysis C_LIO_LIOTA exposure disrupts mitochondrial fission and fusion C_LIO_LIOTA induced mitochondrial ROS C_LIO_LIEarly mitochondrial stress may underlie OTA-associated CKDu risk C_LI

Explore related subjects

pharmacology and toxicologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Mahadeo, A., Bammler, T. K., MacDonald, J., Zheng, A. R., Yeung, C. K., Himmelfarb, J., Kelly, E. J.. 2025-09-04. Evaluation of toxicological mechanisms of ochratoxin-A in human primary proximal tubule epithelial cells. https://doi.org/10.1101/2025.08.29.673189

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Context and exposure history shape insecticide sensitivity in Drosophila melanogaster

Current insecticide toxicology still lacks an integrated understanding of how lethal and sublethal exposure shape organismal performance across biologically and environmentally relevant contexts. In particular, insecticide susceptibility may vary with physiological state, environmental conditions, and recent exposure history, factors that are only partially captured by standardized toxicity assessments. Here, using Drosophila melanogaster, we systematically compared responses to three insecticides with distinct modes of action - acetamiprid, chlorantraniliprole, and deltamethrin - across developmental stages, sexes, adult ages, and ambient temperatures. Insecticide sensitivity varied substantially across these conditions, with temperature modulating toxicity in a compound-dependent manner. Notably, deltamethrin caused substantial lethality at concentrations more than 10,000-fold below approved field application rates. Beyond these context-dependent differences in acute toxicity, sublethal pre-exposure to each insecticide rapidly reduced lethality during a subsequent challenge with the same compound, with increased tolerance already detectable after 24 h. Importantly, these exposure conditions that enhanced insecticide tolerance were associated with reduced resistance to environmental challenges, including heat and nutrient starvation, revealing a potential trade-off in organismal stress resilience. Acetamiprid exposure further altered reproductive performance in a concentration-dependent manner, with higher exposure reducing egg production while increasing developmental success among the resulting offspring, such that the number of offspring reaching adulthood remained largely unchanged. Together, these findings demonstrate that insecticide susceptibility is highly context dependent and can be rapidly modified by recent exposure history. We identify short-term, compound-specific, and potentially costly tolerance as an underappreciated consequence of insecticide exposure and highlight the importance of incorporating biological context, environmental conditions, and sublethal exposure history into pesticide risk assessment.

pharmacology and toxicology↗
bioRxiv2026

Aquaporin-9 and aquaporin-10 but not aquaporin-3 confer susceptibility to dimethylarsinic acid genotoxicity in human cells

Human metabolism converts inorganic arsenic to the pentavalent methylated species MMA(V) and DMA(V), the forms most people excrete, and the forms long read as the end of a detoxification pathway. Whether a transporter sets how much of these metabolites reaches the genome has not been tested in a mammalian cell. We expressed human AQP3, AQP7, AQP9 or AQP10 in HEK293T and MRC5-SV40 cells and measured gamma-H2AX by flow cytometry across dose series of As(V), MMA(V) and DMA(V), pairing every aquaporin with a GFP-Tubulin control and an untransfected mock acquired in the same replicate. As(V) was inactive in HEK293T cells and only weakly active in MRC5-SV40 cells to 20 micromolar, and both methylated species damaged DNA only in the millimolar range, DMA(V) being the more potent of the two in both cell lines. Against that weak baseline, AQP9 and AQP10 raised DMA(V)-induced gamma-H2AX in HEK293T cells by roughly 17 percentage points over the matched control, more than doubling the damage the same exposure produced in control cells, whereas AQP3 and AQP7 changed it not at all. AQP9 alone remained active with MMA(V). The ranking held in MRC5-SV40 fibroblasts at one-sixth the size, and within single wells the damage rose with the amount of AQP9 a cell carried while the control was flat. Aquaglyceroporins therefore discriminate among arsenic species, and AQP9 and AQP10 turn a weakly genotoxic metabolite into a substantially more genotoxic one.

pharmacology and toxicology↗
bioRxiv2026

Quantitative Systems Pharmacology Model for Trop-2 Targeting Antibody-Drug Conjugate in Triple-Negative Breast Cancer

TROP2-targeted antibody-drug conjugates (ADCs) have demonstrated promising clinical activity in triple-negative breast cancer (TNBC) as monotherapies; however, therapeutic benefit varies among patients. Combination strategies pairing TROP2-targeted ADCs with immune checkpoint inhibitors are also being investigated. Elucidating the mechanistic drivers of ADC monotherapy variability and enabling the rational development of combination regimens require computational frameworks that integrate ADC pharmacology with tumor-immune interactions. A quantitative systems pharmacology (QSP) model is presented that incorporates an ADC module into our established immuno-oncology model for TNBC. The module captures ADC and payload pharmacokinetics and pharmacodynamics. TNBC heterogeneity is represented by two tumor cell clones with high and low TROP2 expression, informed by prior characterizations, and differential sensitivity to the ADC payload is incorporated as an intrinsic property of each clone. Although generalizable, the model was applied to the TROP2-targeted ADC sacituzumab govitecan (SG, TRODELVY). A virtual patient cohort was generated using Latin hypercube sampling and calibrated against objective response rate (ORR) data from SG Phase I/II TNBC basket trial. The model predicted an ORR of 33.2% consistent with ASCENT study (NCT02574455). Simulations suggest TROP2-mediated delivery contributes modestly to SG efficacy with tumor exposure driven largely by systemically released SN-38 payload being sufficient to induce cytotoxicity. Tumor heterogeneity emerged as a key determinant of response with ORR increasing as the fraction of payload-sensitive clones increased. Overall, this QSP framework for TROP2-targeted ADCs accounts for TNBC heterogeneity and is extendable to other ADCs and targets enabling interrogation of ADC mechanisms of action in conjunction with tumor-immune interactions.

pharmacology and toxicology↗