Necrotic enteritis (NE) is a major enteric disease in poultry, yet effective mitigation strategies remain elusive. Deoxycholic acid (DCA) and butyrate, two major metabolites derived from the intestinal microbiota, have independently been shown to induce host defense peptide (HDP) synthesis. However, the potential synergy between these two compounds remains unexplored. To investigate the possible synergistic effect between DCA and butyrate in regulating HDP synthesis and barrier function, we treated chicken HD11 macrophage cells and jejunal explants with DCA and sodium butyrate (NaB), either individually or in combination, for 24 h. Subsequently, we performed RNA isolation and reverse transcription-quantitative PCR to analyze HDP genes as well as the major genes associated with barrier function. To further determine the synergy between DCA and NaB in enhancing NE resistance, we conducted two independent trials with Cobb broiler chicks. In each trial, the diet was supplemented with DCA or NaB on the day-of-hatch, followed by NE induction through sequential challenges with Eimeria maxima and Clostridium perfringens on d 10 and 14, respectively. We recorded animal mortality after infection and assessed intestinal lesions on d 17. The impact of DCA and NaB on the microbiota in the ileum and cecum was evaluated through bacterial 16S rRNA gene sequencing. We found that the combination of DCA and NaB synergistically induced multiple HDP genes in both chicken HD11 cells and jejunal explants. Additionally, the gene for claudin-1, a major tight junction protein, also exhibited synergistic induction in response to DCA and NaB. Furthermore, dietary supplementation with a combination of 0.75 g/kg DCA and 1 g/kg NaB led to a significant improvement in animal survival and a reduction in intestinal lesions compared to either compound alone in a chicken model of NE. Notably, the cecal microbiota of NE-infected chickens showed a marked decrease in SCFA-producing bacteria such as Bacteroides, Faecalibacterium, and Cuneatibacter, with lactobacilli becoming the most dominant species. However, supplementation with DCA and NaB largely restored the intestinal microbiota to healthy levels. DCA synergizes with NaB to induce HDP and claudin-1 expression and enhance NE resistance, with potential for further development as cost-effective antibiotic alternatives.

中文翻译：

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两种肠道微生物衍生的代谢物，脱氧胆酸和丁酸盐，协同增强宿主防御肽的合成并缓解坏死性肠炎

坏死性肠炎（NE）是家禽的一种主要肠道疾病，但有效的缓解策略仍然难以捉摸。脱氧胆酸（DCA）和丁酸盐是源自肠道微生物群的两种主要代谢物，已被独立证明可以诱导宿主防御肽（HDP）的合成。然而，这两种化合物之间的潜在协同作用仍有待探索。为了研究 DCA 和丁酸盐在调节 HDP 合成和屏障功能方面可能的协同作用，我们用 DCA 和丁酸钠 (NaB) 单独或组合处理鸡 HD11 巨噬细胞和空肠外植体 24 小时。随后，我们进行了 RNA 分离和逆转录定量 PCR 来分析 HDP 基因以及与屏障功能相关的主要基因。为了进一步确定 DCA 和 NaB 在增强 NE 抗性方面的协同作用，我们对 Cobb 肉鸡进行了两项独立试验。在每项试验中，在孵化当天向日粮中添加 DCA 或 NaB，然后分别在第 10 天和第 14 天通过极大艾美耳球虫和产气荚膜梭菌连续攻击来诱导 NE。我们记录了感染后的动物死亡率，并在第 17 天评估了肠道病变。通过细菌 16S rRNA 基因测序评估了 DCA 和 NaB 对回肠和盲肠微生物群的影响。我们发现 DCA 和 NaB 的组合在鸡 HD11 细胞和空肠外植体中协同诱导多个 HDP 基因。此外，claudin-1（一种主要的紧密连接蛋白）基因也表现出对 DCA 和 NaB 的协同诱导作用。此外，在 NE 鸡模型中，与单独使用任一化合物相比，膳食补充 0.75 g/kg DCA 和 1 g/kg NaB 的组合可显着提高动物存活率并减少肠道损伤。值得注意的是，感染 NE 的鸡的盲肠微生物群显示，产生 SCFA 的细菌（如拟杆菌、粪杆菌和楔杆菌）显着减少，其中乳酸杆菌成为最主要的菌种。然而，补充 DCA 和 NaB 在很大程度上使肠道微生物群恢复到健康水平。DCA 与 NaB 协同作用，诱导 HDP 和claudin-1 表达并增强 NE 耐药性，具有进一步开发为具有成本效益的抗生素替代品的潜力。