College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China; Institute of Animal Nutritional Health, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine，Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China.
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China; Institute of Animal Nutritional Health, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine，Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China.
Ecotoxicol Environ Saf. 2022 Apr 15;235:113447. doi: 10.1016/j.ecoenv.2022.113447. Epub 2022 Mar 28.
Ochratoxin A (OTA), frequently existing in the food and feeds, could induce immunotoxicity. Porcine circovirus type 2 (PCV2), as a primary causative agent of porcine circovirus-associated disease, also could induce immunosuppression. However, it is still unknown whether PCV2 infection impacts OTA-induced immunotoxicity. The pigs and porcine alveolar macrophages (PAMs) were used as the model in the present experiment. The results in vivo indicated that PCV2 infection exacerbated OTA-induced immunotoxicity, NF-κB p65 phosphorylation, and TLR4 and MyD88 mRNA and protein expression in spleen. The results in vitro showed that OTA at 7.0 and 9.0 μM decreased cell viability and increased LDH release of PAMs without PCV2 infection. However, with PCV2 infection, OTA at 5.0, 7.0 and 9.0 μM significantly decreased cell viability and increased LDH release compared with absence of PCV2 infection. In addition, OTA at 5.0 and 7.0 μM significantly increased Annexin V/PI-positive rate, apoptosis of nuclear, γ-H2AX foci, IL-1α and TNF-α expression in PAMs with PCV2 infection compared with absence of PCV2 infection. In addition, PCV2 infection enhanced OTA-induced TLR4 and MyD88 mRNA and protein expression and NF-κB p65 phosphorylation. Knockdown of TLR4 alleviated the exacerbating effects of PCV2 infection on OTA-induced cytotoxicity, apoptosis and DNA damage in PAMs. These results indicated that PCV2 infection aggravated OTA-induced immunotoxicity and reduced the dose of OTA-induced immunotoxicity via TLR4/NF-κB p65 signaling pathway, which could provide basis for establishing limits for OTA.
赭曲霉毒素 A（OTA）经常存在于食品和饲料中，可引起免疫毒性。猪圆环病毒 2 型（PCV2）作为猪圆环病毒相关疾病的主要病原体，也可引起免疫抑制。然而，PCV2 感染是否影响 OTA 诱导的免疫毒性尚不清楚。本实验以猪和猪肺泡巨噬细胞（PAMs）为模型。体内结果表明，PCV2 感染加剧了 OTA 诱导的免疫毒性、脾脏 NF-κB p65 磷酸化以及 TLR4 和 MyD88mRNA 和蛋白表达。体外结果表明，在没有 PCV2 感染的情况下，OTA 在 7.0 和 9.0 μM 时降低了 PAMs 的细胞活力并增加了 LDH 的释放。然而，在有 PCV2 感染的情况下，与没有 PCV2 感染相比，OTA 在 5.0、7.0 和 9.0 μM 时显著降低了细胞活力并增加了 LDH 的释放。此外，与没有 PCV2 感染相比，OTA 在 5.0 和 7.0 μM 时显著增加了 PCV2 感染的 PAMs 中的 Annexin V/PI 阳性率、核凋亡、γ-H2AX 焦点、IL-1α 和 TNF-α 的表达。此外，PCV2 感染增强了 OTA 诱导的 TLR4 和 MyD88mRNA 和蛋白表达以及 NF-κB p65 磷酸化。TLR4 的敲低减轻了 PCV2 感染对 PAMs 中 OTA 诱导的细胞毒性、凋亡和 DNA 损伤的加重作用。这些结果表明，PCV2 感染加剧了 OTA 诱导的免疫毒性，并通过 TLR4/NF-κB p65 信号通路降低了 OTA 诱导的免疫毒性的剂量，这可为建立 OTA 限量提供依据。
