AFB1 and OTA Promote Immune Toxicity in Human LymphoBlastic T Cells at Transcriptomic Level

Abstract

Aflatoxin B1 (AFB1) and ochratoxin A (OTA) are typical contaminants of food and feed, which have serious implications for human and animal health, even at low concentrations. Therefore, a transcriptomic study was carried out to analyze gene expression changes triggered by low doses of AFB1 and OTA (100 nM; 7 days), individually and combined, in human lymphoblastic T cells. RNA-sequencing analysis showed that AFB1-exposure resulted in 99 differential gene expressions (DEGs), while 77 DEGs were obtained in OTA-exposure and 3236 DEGs in the combined one. Overall, 16% of human genome expression was altered. Gene ontology analysis revealed, for all studied conditions, biological processes and molecular functions typically associated with the immune system. PathVisio analysis pointed to ataxia telangiectasia mutated signaling as the most significantly altered pathway in AFB1-exposure, glycolysis in OTA-exposure, and ferroptosis in the mixed condition (Z-score > 1.96; adjusted p-value ≤ 0.05). Thus, the results demonstrated the potential DNA damage caused by AFB1, the possible metabolic reprogramming promoted by OTA, and the plausible cell death with oxidative stress prompted by the mixed exposure. They may be considered viable mechanisms of action to promote immune toxicity in vitro.

Keywords: Jurkat cells; RNA-sequencing; immune toxicity; mechanism of action; mycotoxins.

Figure 1

Venn diagram for the DEGs found by RNA-seq in Jurkat cells treated with AFB1, OTA, AFB1 + OTA at 100 nM in 0.1% DMSO compared to 0.1% DMSO control exposure. DEGs p-value ≤ 0.05 and log2FC |0.5|.

Figure 2

Genes involved in ATM signaling for Homo sapiens are shown in red and green. The up-regulated genes are represented in red and the down-regulated ones after AFB1 exposure (100 nM) are represented in green.

Figure 3

Genes implicated in glycolysis senescence pathway for Homo sapiens are represented in red and green. The up-regulated genes are represented in red and the down-regulated ones upon OTA exposure (100 nM) are represented in green.

Figure 4

Genes involved in ferroptosis pathway for Homo sapiens are represented in red and green. The up-regulated genes are represented in red and the down-regulated ones following AFB1-OTA exposure (100 nM for both toxins) are represented in green.

Figure 5

Bar plots showing the relative expression of (A) CSTA and (B) DNTT when compared to the control (Log2RQ = 0) after 7 days of exposure in Jurkat cells to AFB1 (100 nM) for CSTA and to AFB1, OTA, AFB1 + OTA (100 nM in all cases) for DNTT by qPCR. RQ: relative quantification; CTRL: control; CSTA: cystatin A; DNTT: DNA nucleotidylexotransferase. p ≤ 0.05 (*), p ≤ 0.001 (***).