State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, PR China; Key Laboratory of Livestock and Poultry Multi-omics, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, Sichuan Agricultural University, PR China; Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, PR China.
Anyang Animal Disease Control Center, PR China.
Life Sci. 2024 Aug 1;350:122672. doi: 10.1016/j.lfs.2024.122672. Epub 2024 May 4.
Non-esterified fatty acids (NEFAs), key to energy metabolism, may become pathogenic at elevated levels, potentially eliciting immune reactions. Our laboratory's findings of reduced L-histidine in ketotic states, induced by heightened NEFA concentrations, suggest an interrelation with NEFA metabolism. This observation necessitates further investigation into the mitigating role of L-histidine on the deleterious effects of NEFAs. Our study unveiled that elevated NEFA concentrations hinder the proliferation of Bovine Mammary Epithelial Cells (BMECs) and provoke inflammation in a dose-responsive manner. Delving into L-histidine's influence on BMECs, RNA sequencing revealed 2124 genes differentially expressed between control and L-histidine-treated cells, with notable enrichment in pathways linked to proliferation and immunity, such as cell cycle and TNF signaling pathways. Further analysis showed that L-histidine treatment positively correlated with an increase in EdU-555-positive cell rate and significantly suppressed IL-6 and IL-8 levels (p < 0.05) compared to controls. Crucially, concurrent treatment with high NEFA and L-histidine normalized the number of EdU-555-positive cells and cytokine expression to control levels. Investigating the underlying mechanisms, Gab2 (Grb2-associated binder 2) emerged as a central player; L-histidine notably reduced Gab2 expression, while NEFA had the opposite effect (p < 0.05). Gab2 overexpression escalated nitric oxide (NO) production and IL6 and IL8 expression. However, L-histidine addition to Gab2-overexpressing cells resulted in NO concentrations indistinguishable from controls. Our findings collectively indicate that L-histidine can counteract NEFA-induced inflammation in BMECs by inhibiting Gab2 expression, highlighting its therapeutic potential against NEFA-related metabolic disturbances.
非酯化脂肪酸（NEFAs）是能量代谢的关键物质，但其在浓度升高时可能会导致疾病，从而引发免疫反应。我们实验室发现，在由 NEFA 浓度升高引起的酮症状态下，L-组氨酸的含量降低，这表明其与 NEFA 代谢有关。这一观察结果需要进一步研究 L-组氨酸对 NEFA 有害影响的缓解作用。我们的研究表明，升高的 NEFA 浓度以剂量反应的方式抑制牛乳腺上皮细胞（BMEC）的增殖并引发炎症。进一步研究 L-组氨酸对 BMEC 的影响，RNA 测序揭示了对照组和 L-组氨酸处理组之间差异表达的 2124 个基因，其中与增殖和免疫相关的途径显著富集，如细胞周期和 TNF 信号通路。进一步分析表明，L-组氨酸处理与 EdU-555 阳性细胞率的增加呈正相关，并显著抑制了 IL-6 和 IL-8 水平（p<0.05），与对照组相比。重要的是，同时用高浓度的 NEFA 和 L-组氨酸处理可使 EdU-555 阳性细胞数量和细胞因子表达恢复到对照水平。研究其潜在机制，Gab2（Grb2 相关结合蛋白 2）作为一个核心分子出现；L-组氨酸显著降低了 Gab2 的表达，而 NEFA 则产生相反的效果（p<0.05）。Gab2 的过表达增加了一氧化氮（NO）的产生和 IL6 和 IL8 的表达。然而，在 Gab2 过表达的细胞中添加 L-组氨酸会导致 NO 浓度与对照组无明显差异。我们的研究结果表明，L-组氨酸通过抑制 Gab2 的表达可以拮抗 NEFA 诱导的 BMEC 炎症，提示其在治疗 NEFA 相关代谢紊乱方面具有潜在的治疗作用。
