This study aimed to investigate the effects of Nano-cAMP on growth performance, gut development, and microbiota composition in broilers. A total of 108 21-day-old yellow-feathered female chicks were randomly divided into three groups with six replicates per group and six chicks per replicate according to the principle of consistent body weight. Experimental treatments included the following: (1) CON group (basal diet), (2) cAMP group (basal diet + 0.02 g/kg cAMP), and (3) Nano-cAMP group (basal diet + 0.37 g/kg Nano-cAMP liposomes). After a 21-day experimental period, results revealed the following: Compared with the CON group, the Nano-cAMP group exhibited a significantly reduced feed-to-gain ratio (p < 0.05). The cAMP group exhibited a significant increase in duodenal index (p < 0.05), whereas the Nano-cAMP group demonstrated greater jejunal villus height (p < 0.05). Both treatment groups showed significant upregulation of cholecystokinin (CCK) and secretin gene expression (p < 0.05). Analysis of alpha-diversity indices (Chao1, Shannon, Simpson) revealed no significant differences in jejunal and cecal microbiota composition between experimental groups (p > 0.05). Notably, the relative abundance of Firmicutes significantly increased (p < 0.05) in the cAMP and Nano-cAMP groups, whereas Proteobacteria, Gemmatimonadota, and Chloroflexi significantly decreased (p< 0.05). The combined relative abundance of three Lactobacillus genera and Bifidobacterium was obviously elevated. Linear discriminant analysis identified Bifidobacterium, Ruminococcus torques group, and uncultured_Thermoanaerobacterales_bacterium as dominant genera in the intestinal tract of Nano-cAMP group. In conclusion, dietary addition of Nano-cAMP promotes jejunal development, modulates appetite hormones mRNA expression, enhances absorption capacity, increases the relative abundance of intestinal probiotics such as Bifidobacterium and cellulose-degrading bacteria such as Ruminococcus torques group, optimizes gut microbiota composition, and ultimately reduces the feed-to-gain ratio in broilers.

Melittin, a natural antimicrobial peptide, has broad-spectrum antimicrobial activity. This has resulted in it gaining increasing attention as a potential antibiotic alternative; however, its practical use has been limited by its weak antimicrobial activity, high hemolytic activity, and low proteolytic stability. In this study, N-terminal fatty acid conjugation was used to develop new melittin-derived lipopeptides (MDLs) to improve the characteristics of melittin. Our results showed that compared with native melittin, the antimicrobial activity of MDLs was increased by 2 to 16 times, and the stability of these MDLs against trypsin and pepsin degradation was increased by 50 to 80%. However, the hemolytic activity of the MDLs decreased when the length of the carbon chain of fatty acids exceeded 10. Among the MDLs, the newly designed analog Mel-C8 showed optimal antimicrobial activity and protease stability. The antimicrobial mechanism studied revealed that the MDLs showed a rapid bactericidal effect by interacting with lipopolysaccharide (LPS) or lipoteichoic acid (LTA) and penetrating the bacterial cell membrane. In conclusion, we designed and synthesized a new class of MDLs with potent antimicrobial activity, high proteolytic stability, and low hemolytic activity through N-terminal fatty acid conjugation.

The interaction forces and mechanical properties of the interaction between melittin (Mel) and lipopolysaccharide (LPS) are considered a crucial driving force for Mel in killing Gram−negative bacteria (GNB). However, how their interaction forces are performed at the single−molecule level and the dissociation kinetic characteristics of the Mel/LPS complex remain poorly understood. In this study, the single−molecule level interaction forces between Mel and LPSs from E. coil K−12, O55:B5, O111:B4, and O128:B12 were explored using atomic force microscopy (AFM) based single−molecule force spectroscopy (SMFS). Further, the AFM−based dynamic force spectroscopy (DFS) and advanced analytical model were employed to investigate the kinetic characteristics of the Mel/LPSs complex dissociation. The results indicated that Mel could interact with both rough (R)−form LPS (E. coli K−12) and smooth (S)−form LPSs (E. coli O55:B5, O111:B4, O128:B12), and the S−form LPSs showed a more robust interaction with Mel than R−form LPS, and a slight difference existed in the interaction forces between Mel and diverse S−form LPSs. The Mel interacts with S−form LPSs showed greater specific and non−specific interaction forces than R−form LPS (p < 0.05), as determined by AFM−based SMFS. However, there was no significant difference in the specific and non−specific interaction forces among the three S−form LPSs (p > 0.05), indicating the variability of O−antigen could not affect the interaction between Mel and LPSs. The DFS result showed that the Mel/S−form LPSs complexes had a lower dissociation rate constant (koff), a shorter energy barrier width (xβ), a longer bond lifetime (τoff), and a higher height of the energy barrier (∆G), demonstrating that Mel could interact with S−form LPSs to form more stable complexes. In conclusion, this study promotes our knowledge of the interaction micromechanics and kinetics characteristics between Mel and LPS at the single−molecule level. Moreover, it can help us design and evaluate new anti−GNB drugs.

The interaction forces and mechanical properties of the interaction between melittin (Mel) and lipopolysaccharide (LPS) are considered to be crucial driving forces for Mel when killing Gram-negative bacteria (GNB). However, how their interaction forces perform at the single-molecule level and the dissociation kinetic characteristics of the Mel/LPS complex remain poorly understood. In this study, the single-molecule-level interaction forces between Mel and LPSs from E. coli K-12, O55:B5, O111:B4, and O128:B12 were explored using atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS). AFM-based dynamic force spectroscopy (DFS) and an advanced analytical model were employed to investigate the kinetic characteristics of the Mel/LPS complex dissociation. The results indicated that Mel could interact with both rough (R)-form LPS (E. coli K-12) and smooth (S)-form LPSs (E. coli O55:B5, O111:B4, and O128:B12). The S-form LPS showed a more robust interaction with Mel than the R-form LPS, and a slight difference existed in the interaction forces between Mel and the diverse S-form LPS. Mel interactions with the S-form LPSs showed greater specific and non-specific interaction forces than the R-form LPS (p < 0.05), as determined by AFM-based SMFS. However, there was no significant difference in the specific and non-specific interaction forces among the three samples of S-form LPSs (p > 0.05), indicating that the variability in the O-antigen did not affect the interaction between Mel and LPSs. The DFS result showed that the Mel/S-form LPS complexes had a lower dissociation rate constant, a shorter energy barrier width, a longer bond lifetime, and a higher energy barrier height, demonstrating that Mel interacted with S-form LPS to form more stable complexes. This research enhances the existing knowledge of the interaction micromechanics and kinetic characteristics of Mel and LPS at the single-molecule level. Our research may help with the design and evaluation of new anti-GNB drugs.

The immunity-related functions of defensins seem to be dependent on environmental stimuli, the cell type, and the concentration of peptides. However, the function and mechanism of porcine β-defensin 114 (pBD114) in regulating the inflammatory response to macrophages are unclear. Therefore, the modulatory effects of porcine pBD114 on the inflammatory response were investigated by treating the mouse monocyte macrophage cell line RAW264.7 with different concentrations of pBD114 with or without lipopolysaccharide (LPS). RNA-seq analysis was performed to investigate the mechanisms underlying pBD114’s regulation of inflammatory responses in macrophages. In addition, the inflammatory response-modulating effects of pBD114 were also further verified with a mouse assay. The results showed that 100 μg/mL of pBD114 significantly promoted the secretion of TNF-α and IL-10 in RAW264.7. However, the LPS-induced increase in TNFα in the RAW264.7 cell cultures was significantly decreased with 10 μg/mL of pBD114. These results suggest that pBD114 can exhibit pro-inflammatory activities under normal physiological conditions with 100 μg/mL of pBD114, and anti-inflammatory activities during an excessive inflammatory response with 10 μg/mL of pBD114. RNA-seq analysis was performed to gain further insights into the effects of pBD114 on the inflammatory response. Among the pBD114-promoting RAW264.7 pro-inflammatory responses, pBD114 significantly up-regulated 1170 genes and down-regulated 724 genes. KEGG enrichment showed that the differentially expressed genes (DEGs) were significantly enriched in the immune- and signal-transduction-related signaling pathways. Protein-Protein Interaction (PPI) and key driver analysis (KDA) analyses revealed that Bcl10 and Bcl3 were the key genes. In addition, pBD114 significantly up-regulated 12 genes and down-regulated 38 genes in the anti-inflammatory response. KEGG enrichment analysis revealed that the DEGs were mainly enriched in the “Cytokine–cytokine receptor interaction” signaling pathway, and PPI and KDA analyses showed that Stat1 and Csf2 were the key genes. The results of qRT-PCR verified those of RNA-seq. In vivo mouse tests also confirmed the pro- or anti-inflammatory activities of pBD114. Although the inflammatory response is a rapid and complex physiological reaction to noxious stimuli, this study found that pBD114 plays an essential role mainly by acting on the genes related to immunity, signal transduction, signaling molecules, and interactions. In conclusion, this study provides a certain theoretical basis for the research and application of defensins.

本试验旨在基于转录组研究猪β-防御素114(PBD114)在巨噬细胞中的免疫调节作用及机制.试验采用不同浓度(1～256 μg/mL)的PBD114处理猪肺泡巨噬细胞3D4/21,并分别在1、3、6和12 h收集细胞培养液,采用酶联免疫吸附试验(ELISA)法检测肿瘤坏死因子-α(TNF-α)和白细胞介素-10(IL-10).为更加深入揭示PBD114在巨噬细胞中的免疫调节作用及机制,本试验通过转录组分析0(MOCK组)和100 μg/mL PBD114(PBD114组)对培养12 h猪肺泡巨噬细胞3D4/21相关基因表达的影响,并采用实时荧光定量PCR(qRT-PCR)验证转录组测序结果.结果表明:1)适宜浓度PBD114能够显著促进猪肺泡巨噬细胞3D4/21分泌TNF-α和IL-10(P＜0.05),并且存在剂量依赖和时间效应.2)转录组测序表明,MOCK组和PBD114组共鉴定出1 894个差异表达基因(DEGs).其中,与MOCK组相比,PBD114组CXC基序趋化因子配体2(CXCL2)、白细胞介素-1β(IL-1β)、集落刺激因子3(CSF3)、白血病抑制因子(LIF)和白细胞介素-1α(IL-1α)等1 170个基因显著上调[差异倍数(FC)≥2,校正P值(ad-justed P-value)≤0.001],B 细胞淋巴瘤 6β(Bcl6β)、B 细胞淋巴瘤 3(Bcl3)、CD2、CD4 和 CD83等724个基因显著下调(FC≥2,adjusted P-value≤0.001).DEGs基因本体(GO)功能注释主要分布在分子功能、细胞组分和生物过程,DEGs数量分别是1 832、1 844和1 802个;京都基因与基因组百科全书(KEGG)通路显著富集到95条(Q＜0.05),其中肿瘤坏死因子(TNF)信号通路、丝裂原活化蛋白激酶(MAPK)信号通路、核因子-κB(NF-κB)信号通路、Toll样受体(TLR)信号通路和白细胞介素-17(IL-17)信号通路等信号通路参与免疫激活,DEGs数量分别是38、66、33、29和27个;蛋白质-蛋白质互作(PPI)和关键驱动分析(KDA)分析表明,RELB、TNF-α诱导蛋白3(TNFAIP3)和TNF受体相关因子1(TRAF1)等基因在PBD114调节巨噬细胞免疫中起着关键作用.3)qRT-PCR验证结果表明,8个随机选择的DEGs的表达趋势与转录组测序结果一致.由此可见,PBD114可以通过RELB、TNFAIP3和TRAF1等关键基因,以及TNF、MAPK、NF-κB、TLR和IL-17等信号通路激活巨噬细胞免疫.

This study explored the effects of pBD114 (porcine &beta;-defensin 114) on inflammatory response. The results in RAW264.7 cells showed that 100 &mu;g/mL of pBD114 significantly increased the concentrations of TNF&alpha; and IL-10, and 10 &mu;g/mL of pBD114 significantly decreased the concen-tration of TNF&alpha; in LPS-induced RAW264.7 cell cultures at 10 ng/mL. These results suggest that pBD114 can exhibit pro-inflammatory or anti-inflammatory activities under certain conditions. RNA-seq analysis was performed to gain further insight into the effects of pBD114 on the in-flammatory response. Among pBD114 promoting RAW264.7 pro-inflammatory response, pBD114 significantly up-regulated 1170 genes and down-regulated 724 genes. KEGG enrichment found that the DEGs were significantly enriched in immune- and signal-transduction-related signaling pathways. PPI and KDA analyses revealed that Bcl10 and Bcl3 were the key genes. In addition, pBD114 significantly up-regulated 12 genes and down-regulated 38 genes in the an-ti-inflammatory response. KEGG enrichment analysis revealed that the DEGs were mainly en-riched in the "Cytokine-cytokine receptor interaction" signaling pathway, and PPI and KDA analyses showed that Stat1 and Csf2 were the key genes. The results of qRT-PCR verified those of RNA-seq. In vivo mice tests also confirmed the pro- or anti-inflammatory activity of pBD114. Although the inflammatory response is a rapid and complex physiological reaction to noxious stimuli, this study found that pBD114 plays an essential role in the inflammatory response mainly by acting on genes related to immunity, signal transduction, signaling molecules, and interactions.

[背景]感染产气荚膜梭菌会引起动物坏死性肠炎,通常使用抗生素进行预防和治疗.随着我国饲料禁抗、养殖减抗的实施,寻找绿色微生态制剂及其代谢产物成为当前研究的热点.[目的]旨在研究前期筛选的一株抑制产气荚膜梭菌的枯草芽孢杆菌BS-2特性.[方法]检测了菌株生长曲线、代谢物质的抑菌特性及细菌素基因簇mRNA表达.[结果]枯草芽孢杆菌BS-2代谢物质对革兰氏阴性菌无抑制作用,而对革兰氏阳性菌具有较强的抑菌性能,并且对产气荚膜梭菌的抑菌性能在2-12 h内迅速增长,在12-24 h内抑菌性能较稳定;该抑菌性能不受胃蛋白酶、胰蛋白酶、蛋白酶K的影响,具有良好的热稳定性;进一步分析抑菌物质基因簇mRNA表达,发现枯草芽孢杆菌BS-2抑制产气荚膜梭菌的活性可能与表面活性素(surfactin)和美杀菌素(mersacidin)表达有关.[结论]枯草芽孢杆菌BS-2对产气荚膜梭菌具有较强的抑制作用,可能通过抑菌物质surfactin和mersacidin表达发挥作用.

试验旨在优化1株产脂环七肽的类芽孢杆菌(Paenibacillus)的中试发酵参数,以提高脂环七肽产量.采用单因素试验设计,研究发酵时间(22、24、26、30 h)及在中试发酵基质中添加不同水平葡萄糖(3.70、4.44 kg/m3)、豆粕(46.3、55.6、64.8 kg/m3)或2种无机盐对类芽孢杆菌产脂环七肽的影响.结果表明:发酵时间及豆粕和无机盐的添加量可影响类芽孢杆菌中试发酵合成脂环七肽的产量(P<0.05),优化的发酵基质组成为55.6 kg/m3豆粕、3.70 kg/m3葡萄糖、3.33 kg/m3碳酸钙、1.11 kg/m3硫酸镁、1.11 kg/m3磷酸氢二钾、1.11 kg/m3磷酸二氢钾、0.22 kg/m3硫酸锰,发酵时间以26 h为宜.在此优化条件下,脂环七肽的产量从1.04％提高到1.64％,为优化前的1.57倍,可为脂环七肽产业化开发提供参考.

饲用抗生素的禁用给养殖业带来巨大挑战,寻找饲用抗生素替代品迫在眉睫.海藻提取物具有提高动物生产性能、改善肠道形态、维持肠道微生物平衡、促进免疫器官发育、降低炎症并提高机体抗氧化能力等特点,具有成为饲用抗生素替代品的潜力.本文重点综述了海藻提取物对猪和鸡生产性能、肠道健康、免疫力和抗氧能力影响的研究进展,为海藻提取物在养殖业上的应用提供理论依据.

Context In-feed antibiotics are commonly used to improve growth and gut health of weaning pigs. Due to anti-microbial resistance by extensively using antibiotics, however, in-feed antibiotics have been banned in Europe and China. Tremella fuciformis is a traditional edible fungus in China. Recent studies have found that Tremella fuciformis extract (TFE) has anti-inflammatory, anti-cancer and immune-modulatory functions. Therefore, there is the potential to develop Tremella fuciformis as an alternative to antibiotics. Aims The study was performed to explore the effects of TFE on growth performance, and biochemical and immunological parameters of weaned piglets under lipopolysaccharide (LPS) challenge. Methods Forty-eight weaned piglets were assigned into two groups with six pens (four piglets per-pen), receiving a control diet or a control diet with 400 mg/kg TFE (TFE), respectively. After 28 days of the trial, two piglets per pen were selected to be injected with LPS (50 μg/kg of BW) or an equivalent amount of sterile saline. Blood samples were collected at 0 and 3 h after LPS challenge. Key results The results showed that TFE supplementation significantly increased the average daily gain (P < 0.05) and decreased the faecal score (P < 0.05) during the first week, improved the feed conversion ratio (P < 0.05) and BWt gain (P < 0.05) during the whole period. Piglets fed the TFE diet had higher plasma levels of white blood cells (P < 0.05) than that of piglets fed the control diet diet before the LPS challenge. Regardless of the dietary treatment, the LPS challenge significantly decreased the level of white blood cells, and increased the levels of red blood cells, haemoglobin, haematocrit, total protein, interleukin-1β and tumour necrosis factor-α (all P < 0.05). Regardless of the LPS challenge, however, the concentrations of total protein, interleukin-1β and tumour necrosis factor-α were decreased (all P < 0.05) in the plasma of piglets fed the TFE diet compared with the control diet diet. Conclusions In summary, the supplementation of TFE in the weaning diet could improve the growth performance and immunity of piglets. Implication TFE could be used as a bioactive substance for improving growth and immune response in pig production.

Context In-feed antibiotics are commonly used to improve growth and gut health of weaning pigs. Due to anti-microbial resistance by extensively using antibiotics, however, in-feed antibiotics have been banned in Europe and China. Tremella fuciformis is a traditional edible fungus in China. Recent studies have found that Tremella fuciformis extract (TFE) has anti-inflammatory, anti-cancer and immune-modulatory functions. Therefore, there is the potential to develop Tremella fuciformis as an alternative to antibiotics. Aims The study was performed to explore the effects of TFE on growth performance, and biochemical and immunological parameters of weaned piglets under lipopolysaccharide (LPS) challenge. Methods Forty-eight weaned piglets were assigned into two groups with six pens (four piglets per-pen), receiving a control diet or a control diet with 400 mg/kg TFE (TFE), respectively. After 28 days of the trial, two piglets per pen were selected to be injected with LPS (50 μg/kg of BW) or an equivalent amount of sterile saline. Blood samples were collected at 0 and 3 h after LPS challenge. Key results The results showed that TFE supplementation significantly increased the average daily gain (P < 0.05) and decreased the faecal score (P < 0.05) during the first week, improved the feed conversion ratio (P < 0.05) and BWt gain (P < 0.05) during the whole period. Piglets fed the TFE diet had higher plasma levels of white blood cells (P < 0.05) than that of piglets fed the control diet diet before the LPS challenge. Regardless of the dietary treatment, the LPS challenge significantly decreased the level of white blood cells, and increased the levels of red blood cells, haemoglobin, haematocrit, total protein, interleukin-1β and tumour necrosis factor-α (all P < 0.05). Regardless of the LPS challenge, however, the concentrations of total protein, interleukin-1β and tumour necrosis factor-α were decreased (all P < 0.05) in the plasma of piglets fed the TFE diet compared with the control diet diet. Conclusions In summary, the supplementation of TFE in the weaning diet could improve the growth performance and immunity of piglets. Implication TFE could be used as a bioactive substance for improving growth and immune response in pig production.

Intestinal epithelial cells (IECs) offer a primary physical barrier against commensal and pathogenic microorganisms in the gastrointestine. However, the influence of IECs on the development and regulation of mucosal immunity to infection is unknown. Here, we show that the porcine β-defensin 114 (PBD114) is an endotoxin-responsive gene expressed in IECs. Analysis on expression profiling of PBD114 gene using an infected porcine model and IPEC-J2 cells unveiled a pattern of induction in response to stimulation of various toll-like receptors (TLRs). By means of promoter analysis, PBD114 was found to be a NF-κB-dependent gene. Importantly, PBD114 suppresses endotoxin-induced inflammation and apoptosis in IECs through downregulation of two critical inflammation-associated signaling proteins, NF-kappa-B inhibitor alpha (IkB-α) and extracellular signal-regulated kinase1/2 (ERK1/2). PBD114 also suppresses inflammation and IEC apoptosis in mice exposed to bacterial endotoxins. Thus, we propose that TLR-activated NF-kB rapidly increases the expression of PBD114 that operates a feedback control of the NF-kB-dependent inflammation. The NF-kB-dependent induction of PBD114 may be a key event through which the mammalian host maintains intestinal epithelium homeostasis in response to various infections or diseases.

Bombyx mori gloverin A2 (BMGlvA2) is an induced antimicrobial insect protein isolated from Bombyx mori. This study was conducted to explore the effect and potential mechanisms of BMGlvA2 on inflammatory responses and cellular functions in intestinal epithelial cells (IPEC-J2) exposure to enterotoxigenic E. coli (ETEC). IPEC-J2 cells pretreated with or without BMGlvA2 (12.5 μg/mL) were challenged by ETEC K88 (1×106 CFU/well) or culture medium. We show that BMGlvA2 pretreatment increased the cell viability and improved the distribution and abundance of tight junction protein ZO-1 in IPEC-J2 cells exposure to ETEC (P < 0.05). Interestingly, BMGlvA2 not only decreased the expression levels of inflammatory cytokines such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), but also decreased the expression level of Caspase3 and the apoptosis rate in the ETEC-challenged cells (P < 0.05). Importantly, BMGlvA2 decreased the protein abundances of two critical inflammation-associated signaling proteins, phosphorylated nuclear factor-kappa-B inhibitor alpha (p-IκBα) and phosphorylated nuclear factor-kappa B (p-NF-κB), in the ETEC-challenged cells. These results indicate that BMGlvA2 attenuates ETEC-induced inflammation in the IPEC-J2 cells by regulating the NF-κB signaling pathway, resulting in decreased secretion of inflammatory cytokine and reduced cell apoptosis.

Essential oils (EO) are concentrated hydrophobic liquids containing volatile aromatic compounds obtained from plants, which have properties as withdrawn antibiotic growth promoters. The objective of this study was to explore the effects of EO on growth performance, digestibility, immunity and intestinal health in broilers. A total of 500 1-day-old Arbor Acre broilers were randomly put into five groups with 10 replicate cages containing 10 birds each. Birds in the 5 groups were fed a basal diet (CON), and basal diet with 50, 100, 200 or 400 mg/kg EO (EO0.5, EO1, EO2 and EO4) for 42 d respectively. Birds were euthanized at 21d and 42 d, blood and tissue samples were collected. In the study, the digestibility of DM, GE and EE in groups with EO supplementation were significantly increased compared with CON group (P < 0.05). However, only EO2 and EO4 significantly increased the digestibility of CP compared with CON group (P < 0.05). In contrast to CON group, EO0.5 and EO1 in jejunum at 21 d, and EO1 in jejunum at 42 d markedly increased the activity of sucrase (P < 0.05). In addition, the level of SOD of EO2 and EO4 in serum at 21 d was significantly increased compared with CON group (P < 0.05). What's more, the concentration of intestinal mucosa SIgA in jejunum and ileum at 21 d of groups with EO supplementation was significantly increased compared with CON group (P < 0.05). Moreover, V/C in jejunum at 21 d of groups with EO supplementation, CD in jejunum at 42 d was also significantly increased to compare with CON group (P < 0.05). Furthermore, the expression levels of critical genes associated with nutrient transportation (i.e., GLUT2, SGLT1, SLC38A, SLC79A and SLC27A4) and barrier function (TJP1) were quadratically and linearly up-regulated in jejunum and ileum with EO supplementation (P < 0.05). These results suggest that EO has a positive impact on growth, immunity and intestinal health in broilers, and 200 mg/kg of EO was recommended in broiler diet.

猪β-防御素是一种先天免疫小分子蛋白质,在宿主防御中起着重要作用.它们不仅具有抗细菌和病毒的活性,还能通过连接先天性免疫和适应性免疫来调节免疫功能,抵抗病原体的感染.基于猪β-防御素的抗微生物活性及其免疫调节功能,其既可以作为提高免疫力的内在潜力,也可以开发成外源应用的抗生素替代品.本文将综述猪β-防御素的表达与分布、表达调控、生物学功能及其异源表达.

β-defensin family plays a critical role in host defense against infections. In this study, we found that pBD129 are widely expressed in porcine tissues such as the intestine, liver, and spleen. Interestingly, the expression level of pBD129 in most tissues was higher in Tibetan pigs than in DLY (Duroc × Landrace × Yorkshire) pigs (P < 0.05), and was significantly upregulated upon E. coli K88 infection (P < 0.05). The pBD129 protein was successfully expressed in E. coli and the molecule weight was estimated by SDS-PAGE to be 37.2 kDa. Mass spectrometry verified the protein as a pBD129. The protein showed antibacterial activities against Streptococcus and E. coli DH5α with a minimal inhibitory concentration (MIC) of 32 μg/mL. Hemolytic and cytotoxicity assays indicated that pBD129 had no detrimental effect on cell viability. Importantly, pBD129 significantly reduced the apoptosis of porcine intestinal epithelial cells exposure to bacterial endotoxins, which was associated with down-regulation of inflammatory cytokines such as the IL-1β, IL-6 and TNFα (P < 0.05), and down-regulation of apoptosis-related genes such as the caspase-3, caspase-8, and caspase-9 (P < 0.05). These results suggested that pBD129 is a novel modulator of innate immunity involved in mammalian inflammatory responses.

微生物及其发酵产品在改善饲料品质,清除畜牧业产生的废气、污染物以及病死畜禽无害化处理等方面具有重要作用.主要从畜牧微生物的研究方向、筛选来源、筛选方法进行了综述,并提出了新的微生物筛选及应用方法.

抗菌肽(antimicrobial peptides,AMP)是广泛存在于自然界的一类小分子多肽,也是不同生物固有免疫系统的重要组成部分.AMP具有广谱的抗微生物活性和免疫调节功能,不易产生耐药性且无残留,是一种理想的饲用抗生素替代品.文章重点综述了AMP的特性、生物学功能及在断奶仔猪和肉鸡上的应用效果.

β-defensins have attracted considerable research interest because of their roles in protecting hosts from various pathogens. This study was conducted to investigate the expression profiles of the porcine β-defensin 114 (PBD114) in different breeds and in response to infections. Moreover, the function of PBD114 protein was partially investigated. Six Tibetan pigs (TP) and six DLY (Duroc×Landrace×Yorkshire) pigs were slaughtered to explore the expression profiles of PBD114 in different breeds and tissues. For infection models, sixteen DLY pigs were divided into two groups and challenged either with sterile saline or E. coli K88. The recombinant protein PBD114 (rPBD114) was obtained by using a heterologous expression system in E. coli. PBD114 gene was highly expressed in tissues such as the intestine, liver, spleen, and thymus. Interestingly, the expression level of PBD114 gene was higher in the TP pigs than in the DLY pigs (P < 0.05), and was significantly elevated upon E. coli K88 challenge (P < 0.05). The nucleotide sequences of PBD114 from Tibetan and DLY pigs was identical, and both showed a 210-bp open reading frame encoding a 69-amino acid mature peptide. To explaore the function of PBD114 protein, PBD114 gene was successfully expressed in E. coli Origami B (DE3) and the molecular weight of the rPBD114 was estimated by SDS-PAGE to be 25 kDa. The rPBD114 was purified and mass spectrometry verified the protein as PBD114. Importantly, rPBD114 showed antimicrobial activities against E. coli DH5α and E. coli K88, and the minimal inhibitory concentrations (MICs) were 64 and 128 μg/mL, respectively. Hemolytic and cytotoxicity assays showed that rPBD114 did not affect cell viability under physiological concentrations. PBD114 is an infection response gene that is differentially-expressed between different porcine breeds and tissues. The antimicrobial activity of PBD114 protein, against pathogens such as the E. coli K88, suggested that it may serve as a candidate for the substitution of conventionally used antibiotics.