ABSTRACT

• 1. This study evaluated and characterised the effect of folic acid (FA) on chromosomal DNA methylation and the epigenetic result on gene expression control mechanisms in chicken B cells as a model of antigen presenting cells.

• 2. After FA supplementation, the methylation pattern on the proximal promoter area and mRNA expression of toll-like receptor (TLR) 2b, TLR4, B cell receptor (BCR) immunoglobulin (Ig) β and major histocompatibility complex (MHC) II β chain genes in chicken B cells was observed

• 3. Chicken B cell line (DT40) cultures were incubated with 0, 1.72 or 3.96 mM of FA for 4 and 8 h and samples were taken at specific time points. After 4 h of incubation, cells were challenged with 0, 1 or 10 µg/ml of lipopolysaccharide (LPS) and samples were collected 4 h post-challenge.

• 4. FA supplementation modified the methylation patterns of the proximal promoter regions of TLR4, Igß, and MHCII ß chain at 4 and 8 hours of incubation; however, the single CpG dinucleotide of TLR2b remained methylated regardless of the treatment.

• 5. A positive association was found between FA concentration and percentage DNA methylation on the promoter area of Igβ and TLR2b. However, there was a negative association between FA and MHCII β chain.

• 6. There were downregulatory effects in TLR4, Igß and MHCII ß chain gene expression after 8 h of incubation, nut not at 4 h. Although incubation time did not affect TLR2b gene expression, FA concentration did, whereby it increased TLR2b expression at 1.72 mM FA (P < 0.05).

• 7. LPS significant downregulated TLR2b expression, while an interaction between FA and LPS concentration affected TLR4 and Igβ gene expression.

• 8. In conclusion, the results showed that FA can have an immunomodulatory effect on chicken B cells, possibly affecting their ability to both recognise antigens through the TLR and BCR pathways, and to present it via the MHCII presentation pathway.

摘要

• 1.这项研究评估并表征了叶酸（FA）对鸡B细胞作为抗原呈递细胞模型的染色体DNA甲基化的影响以及表观遗传结果对基因表达控制机制的影响。

• 2.补充FA后，Toll样受体（TLR）2b，TLR4，B细胞受体（BCR）免疫球蛋白（Ig）β和主要组织相容性复合体（MHC）IIβ链的近端启动子区域甲基化模式和mRNA表达观察到鸡B细胞中的基因

• 3.将鸡B细胞系（DT40）培养物与0、1.72或3.96 mM FA孵育4和8 h，并在特定时间点取样。孵育4小时后，用0、1或10 µg / ml脂多糖（LPS）攻击细胞，并在攻击后4小时收集样品。

• 4. FA的添加在孵育4和8小时后改变了TLR4，Igß和MHCIIβ链近端启动子区域的甲基化模式；然而，无论处理如何，TLR2b的单个CpG二核苷酸仍保持甲基化。

• 5.在Igβ和TLR2b的启动子区域上，FA浓度和DNA甲基化百分比之间存在正相关。然而，FA和MHCIIβ链之间存在负相关。

• 6.孵育8小时后，TLR4，Igß和MHCIIß链基因表达有下调作用，但在4 h时则没有。尽管温育时间不影响TLR2b基因表达，但FA浓度会影响FAR，从而在1.72 mM FA下增加TLR2b表达（P <0.05）。

• 7. LPS显着下调了TLR2b表达，而FA和LPS浓度之间的相互作用影响TLR4和Igβ基因表达。

• 8.总之，结果表明FA可以对鸡B细胞具有免疫调节作用，可能会影响它们通过TLR和BCR途径识别抗原并通过MHCII呈递途径呈递抗原的能力。