Heat stress (HS) disrupts the gut barrier allowing the uptake of lipopolysaccharide (LPS) and leads to an inflammatory response and changes in gut microbiota composition. Moringa oleifera leaf powder (MOLP) has been proposed to combat HS, yet its alleviate role is currently under investigation. The current study investigated the effects of chronic HS and MOLP supplementation on changes in redox status and immune response of cecal mucosa along with alteration in cecal microbiota. A total of 21 young New Zealand White (NZW) rabbits (male) about 32 weeks old (mean body weight of 3318 ± 171 g) reared on a commercial pelleted diet were employed; divided into three groups (n = 7): control (CON, 25 °C), heat stress (HS, 35 °C for 7 h daily), and HS supplemented orally with MOLP (HSM, 35 °C) at 200 mg/kg body weight per day for 4 weeks. The results demonstrated that MOLP supplementation increased organ index of cecal tissue compared with the HS group (P > 0.05). Levels of malonaldehyde (MDA) and activity of superoxide dismutase (SOD) as well as lactate dehydrogenase (LDH) were reduced in the cecal mucosa of the HSM group compared with the HS group. MOLP downregulated the contents of cecal mucosa LPS, several inflammatory markers (TNF-α/IL-1α/IL-1β), and myeloperoxidase (MPO) in the HSM group (P < 0.05). Secretory immunoglobulin A (SIgA) was increased in the HSM group compared with the HS group (P < 0.05). The transcriptome of cecal mucosa showed that MOLP reduced gene expression relative to several immune factors, including IL-10, IFNG, and RLA, whereas both HS and MOLP increased the gene expression of fat digestion and absorption pathway, including APOA1, FABP1, FABP2, MTTP, and LOC100344166, compared to the CON group (P < 0.001). At the phylum level, the relative abundance of Proteobacteria was increased by HS, while Actinobacteria was significantly increased by HSM compared to other groups (P < 0.05). At genus level, Papillibacter was higher in abundance in HSM groups compared to CON and HS groups (P < 0.05). Higher butyrate concentrations were observed in the HSM group than HS and CON groups (P < 0.05). In conclusion, HS in growing rabbits resulted in alteration of cecal microbiota at phyla level as well as increased oxidative stress and expression of mucosal inflammatory genes. Whereas, oral MOLP supplementation elevated the relative weight of cecum, affected their immunological and cecal micro-ecosystem function by improving antioxidant status and down-regulating mucosal tissue inflammatory response.

中文翻译：

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新西兰白兔口服辣木叶粉可缓解氧化应激，调节粘膜免疫反应和盲肠菌群

热应激（HS）破坏了肠壁屏障，允许摄取脂多糖（LPS），并导致炎症反应和肠道菌群组成发生变化。辣木叶粉（MOLP）已被提出抗HS，但其缓解作用目前正在研究中。目前的研究调查了长期补充HS和MOLP对盲肠粘膜氧化还原状态和盲肠粘膜免疫反应以及盲肠菌群变化的影响。共有21只约32周龄的新西兰小白兔（NZW）（雄性），以商业颗粒饲料饲养；平均体重为3318±171 g。分为三组（n = 7）：对照组（CON，25°C），热应激（HS，35°C每天7 h）和HS口服200 mg / ml的MOLP（HSM，35°C）每天公斤体重，持续4周。结果表明，与HS组相比，MOLP补充剂可增加盲肠组织的器官指数（P> 0.05）。与HS组相比，HSM组盲肠粘膜中的丙二醛（MDA）水平和超氧化物歧化酶（SOD）活性以及乳酸脱氢酶（LDH）降低。MOLP下调了HSM组盲肠粘膜LPS，几种炎症标志物（TNF-α/IL-1α/IL-1β）和髓过氧化物酶（MPO）的含量（P <0.05）。与HS组相比，HSM组分泌型免疫球蛋白A（SIgA）升高（P <0.05）。盲肠粘膜的转录组显示，相对于几种免疫因子（包括IL-10，IFNG和RLA），MOLP降低了基因表达，而HS和MOLP均增加了脂肪消化和吸收途径的基因表达，包括APOA1，FABP1，FABP2，MT组和LOC100344166与CON组相比（P <0.001）。与其他组相比，在门静脉水平上，HS增加了变形杆菌的相对丰度，而HSM则明显增加了放线菌（P <0.05）。在属水平上，与CON和HS组相比，HSM组中的乳杆菌含量更高（P <0.05）。HSM组的丁酸盐浓度高于HS和CON组（P <0.05）。总之，生长中的兔子的HS导致盲肠微生物群的门水平改变，以及氧化应激的增加和粘膜炎性基因的表达。口服MOLP补充剂会增加盲肠的相对重量，