Exogenous molecules derived from catabolic states (e.g., fatty acids, β-hydroxybutyrate) during periods of stress such as the periparturient period or pathogen challenges [e.g., lipopolysaccharide (LPS)] can trigger an inflammatory response in tissues such as the liver and the mammary gland. Butyrate is one of the major short-chain fatty acids produced in the rumen, and work with non-ruminants has demonstrated that it can alter inflammatory processes. The primary objective of this study was to explore the preventive effect of sodium butyrate (SB) on LPS-induced inflammation in bovine mammary epithelial cells along with underlying molecular mechanisms. Immortalized bovine mammary epithelial cells (MAC-T) were treated with SB (0.1, 0.25, 0.5, 1, 2, or 5 mM) or with the histone deacetylase inhibitor trichostatin A (TSA; 6.25, 12.5, 25, or 50 nM) for 18 h, followed by a challenge with 1 µg/mL LPS for an additional 6 h. Pretreatment with SB prevented increase in apoptosis of LPS-challenged MAC-T cells in a dose-dependent manner. The LPS treatment upregulated mRNA abundance of tumor necrosis factor α (TNFA), interleukin-6 (IL6), and interleukin-1B (IL1B), whereas inhibition of histone deacetylase with TSA dampened this effect. More importantly, SB had clear dose-dependent effects on the inflammatory response by preventing upregulation of TNFA, IL6, and IL1B. Furthermore, pretreatment with TSA or SB attenuated the downregulation of histone H3 acetylation protein abundance induced by LPS. The greater ratio of p-IκB α/IκB α and p-p65/p65 protein abundance and the increase in nuclear localization of NF-κB p65 protein in response to LPS were attenuated by pretreatment with SB. Overall, the data indicated that exogenous SB alleviates mammary cell pro-inflammatory responses partly through post-translational mechanisms that diminish NF-κB signaling. Thus, the cytoprotective effect of SB against an inflammatory challenge might represent a preventive tool to help the mammary gland against pathogens such as those causing mastitis.

在应激期间，例如围产期或病原体挑战[例如，脂多糖（LPS）]，源自分解代谢状态的外源分子（例如，脂肪酸，β-羟基丁酸酯）可以触发组织（例如，肝脏和乳腺）的炎症反应腺。丁酸盐是瘤胃中产生的主要短链脂肪酸之一，与反刍动物一起工作已证明其可以改变炎症过程。这项研究的主要目的是探索丁酸钠（SB）对LPS诱导的牛乳腺上皮细胞炎症的预防作用以及潜在的分子机制。用SB（0.1、0.25、0.5、1、2或5 m M处理永生化的牛乳腺上皮细胞（MAC-T））或与组蛋白脱乙酰基酶抑制剂曲古抑菌素A（TSA; 6.25、12.5、25或50 n M）混合18 h，然后再加1 µg / mL LPS刺激6 h。SB预处理以剂量依赖的方式阻止了LPS攻击的MAC-T细胞凋亡的增加。LPS处理上调了肿瘤坏死因子α（TNFA），白细胞介素6（IL6）和白细胞介素1B（IL1B）的mRNA丰度，而用TSA抑制组蛋白脱乙酰基酶则减弱了这一作用。更重要的是，SB通过阻止TNFA，IL6和IL1B的上调，对炎症反应具有明显的剂量依赖性作用。此外，用TSA或SB预处理减弱了LPS诱导的组蛋白H3乙酰化蛋白丰度的下调。SB预处理可减轻p-IκBα/IκBα和p-p65 / p65蛋白丰度的更大比例以及NF-κBp65蛋白响应LPS的核定位增加。总体而言，数据表明外源性SB部分通过减少NF-κB信号传导的翻译后机制减轻了乳腺细胞的促炎反应。因此，SB对炎性挑战的细胞保护作用可能代表了一种预防工具，可以帮助乳腺抵抗病原体，例如引起乳腺炎的病原体。