双歧杆菌脂磷壁酸与5-氟尿嘧啶体内联用对肿瘤细胞凋亡的影响

目的研究双歧杆菌脂磷壁酸与5-氟尿嘧啶联用诱导H22荷瘤小鼠肿瘤细胞凋亡的作用机制。方法双歧杆菌脂磷壁酸联合5-FU处理H22荷瘤Balb/c小鼠,计算抑瘤率,观察小鼠生存期;采用Real time-PCR和Western blot方法分别检测荷瘤小鼠肿瘤组织Bcl-2、Bax和Caspase-3 mRNA及蛋白的表达变化。结果双歧杆菌脂磷壁酸联合5-FU应用,与单独5-FU处理组比较,不仅抑瘤率明显提高（P〈0.01）,且荷瘤小鼠存活时间明显延长（P〈0.01）,肿瘤组织Bcl-2表达下降,Bax和Caspase-3表达升高（P〈0.05）。结论双歧杆菌脂磷壁酸联合5-FU可通过上调Bax和Caspase-3,下调Bcl-2,促进肿瘤细胞凋亡,从而发挥协同抗肿瘤作用。     

双歧杆菌脂磷壁酸对化疗荷瘤小鼠免疫功能的影响

目的探讨双歧杆菌脂磷壁酸对5-氟尿嘧啶（5-FU）化疗肝癌H22荷瘤小鼠免疫的影响及其作用机制。方法双歧杆菌脂磷壁酸处理5-Fu化疗的H纶荷瘤Balb／c小鼠,MTT法检测NK细胞和CTL细胞杀伤活性;采用流式细胞仪检测荷瘤小鼠脾细胞中T亚群比例;用RT-PCR和Western Not方法分别检测荷瘤小鼠肿瘤组织Foxp3和TIM-3mRNA及蛋白的表达变化。结果荷瘤小鼠脾细胞中CD4^＋ CD25^＋Tmg比例高,并存在Foxp3和TIM-3 mRNA及蛋白的高表达,经双歧杆菌LTA和5．Fu处理后CD4^＋CD25^＋Tmg比例下降,Foxp3和TIM-3mRNA及蛋白表达水平也均呈下调趋势,但5-FU单独处理后的荷瘤小鼠脾细胞中CD4^＋细胞比例也减少,NK细胞和CTL杀伤率均降低,而双歧杆菌LTA处理后CD4^＋细胞比例,NK细胞和CTL杀伤率却明显增加。二者联合处理也能增加CD^＋细胞比例及NK细胞和CTL杀伤率。结论双歧杆菌脂磷壁酸联合5-FU可通过增强NK细胞和CTL杀伤能力,同时抑制TIM-3／TIM-3L途径,降低CD4^＋CD25^＋Tmg的免疫抑制活性,增强机体细胞免疫来提高化疗抗肿瘤效果,减轻化疗副作用,增强宿主对化疗的耐受性,从而提高抗肿瘤作用。     

双歧杆菌脂磷壁酸抗衰老的研究现状

双歧杆菌(Bifidobacterium)是一类无芽胞严格厌氧的革兰阳性杆菌,是人体肠道内重要的生理菌群,正常情况下与人类有着和谐的共生关系。双歧杆菌在体内能调节和维持人体微生态平衡,合成人体所必需的多种维生素等营养物质,拮抗     

双歧杆菌脂磷壁酸生物学活性研究进展

本文综述了双歧杆菌脂磷壁酸(lipoteichoic acid,LTA)的免疫激活、抗肿瘤、抗突变、抗衰老及粘附等重要生物学功能。     

双歧杆菌脂磷壁酸和总DNA对小鼠免疫功能的影响

目的比较双歧杆菌2种组分即双歧杆菌脂磷壁酸（LTA）和总DNA的免疫调节作用。方法分别提取和制备双歧杆菌LTA和总DNA。采用淋巴细胞转化法和溶血空斑法分别研究它们对小鼠细胞和体液免疫的调节作用。结果与对照组比较,双歧杆菌和总DNA对T细胞和B细胞都有明显的刺激作用（P〈0．05或P〈0．01）,但是LTA的作用更强（P〈0．01）。结论双歧杆菌细胞壁的LTA和细胞核的总DNA均具有免疫调节作用,但前者效能优于后者。     

双歧杆菌脂磷壁酸的提取及功能的研究进展

脂磷壁酸是双歧杆菌发挥生理功能的最重要的表面分子之一。在抑制肿瘤细胞、免疫调节、抗氧化、抗衰老等积极作用外,也具有一定的消极作用,但相关的机制尚不明确。本研究针对近年来国内外学者对脂磷壁酸进行的研究做了较为全面的概括总结,为进一步的研究提供了理论基础。     

双歧杆菌脂磷壁酸抗体的制备及其在双歧制品中的检测应用

目的制备双歧杆菌脂磷壁酸抗体并用以检测双歧制品中脂磷壁酸和双歧杆菌活菌的含量。方法提取两歧双歧杆菌脂磷壁酸,加甲基化牛血清白蛋白与佐剂免疫预先已用卡介苗进行多克隆激活的BALB／C小鼠,间接ELISA法检测抗体效价与特异性,用免疫血清经双抗体夹心ELISA法和免疫结合微量培养的方法分别检测酸奶中脂磷壁酸和双歧杆菌活菌量。结果免疫血清最高效价可达1：1280,与所测其他人体双歧杆菌种属存在较强交叉反应,与非双歧杆菌种属无交叉反应。对于脂磷壁酸和双歧杆菌活菌的含量检测取得良好结果,检测线可达10^5 CFU／ml。结论以双歧杆菌脂磷壁酸制备免疫血清,效价高,属特异性好,可用于双歧食品中脂磷壁酸和双歧杆菌活菌的含量检测。     

双歧杆菌脂磷壁酸对D-半乳糖致衰老小鼠表型的影响

目的通过研究双歧杆菌表面分子脂磷壁酸（LTA）对D-半乳糖致衰老小鼠生物表型的影响,探讨双歧杆菌抗衰老的作用。方法雄性昆明系小鼠,随机分组,在建立D-半乳糖诱导的衰老小鼠模型的同时,每日注射双歧杆菌LTA。各组小鼠连续处理8周后处死,观察器官组织形态的变化并测定脏器指数、骨指标、血清指标。结果青年组小鼠骨干重与体重比值为1.52±0.09,血清中NO为（18.79±0.99）μmol/L;模型组小鼠骨干重与体重比值为1.27±0.13（P〈0.01）,血清中NO为（14.03±2.41）μmol/L（P〈0.01）;此外,与对照组相比,模型组小鼠活动减少,胸腺、肾脏、脑及睾丸萎缩;骨钙、骨磷严重减少（P〈0.01）,血钙升高、血尿素氮和肌酐升高（P〈0.05）;而双歧杆菌LTA能显著逆转上述变化。结论双歧杆菌LTA能改善D-半乳糖致衰老小鼠的衰老表型,具有一定的抗衰老作用。     

脂磷壁酸的提取工艺及免疫功能的研究

目的确定婴儿双歧杆菌脂磷壁酸（LTA）的最佳提取工艺及其免疫调节作用。方法通过对不同方法提取婴儿双歧杆菌LTA的测定及对植瘤小鼠淋巴细胞的转化来探讨LTA对小鼠细胞免疫的调节作用。结果采用脱脂后水法提取效果最好,与对照组和全菌组相比,LTA使淋巴细胞转化增加。结论婴儿双歧杆菌及其LTA均有免疫功能,但LTA的效果要优于婴儿双歧杆菌。     

双歧杆菌脂磷壁酸对深部白色念珠菌感染小鼠生存状态的影响

目的观察双歧杆菌脂磷壁酸(BLTA)对深部白色念珠菌感染小鼠生存状态的影响。方法通过尾静脉注射白色念珠菌,建立正常免疫力及免疫力低下小鼠深部白色念珠菌感染模型,观察不同剂量BLTA处理对小鼠体重变化、生存时间以及肾组织真菌负荷量的影响。结果深部白色念珠菌感染小鼠经BLTA处理后,生存状态有所改善,体重下降减慢。对于正常免疫力小鼠,BLTA150组的生存率明显高于未处理组(P0.01);而对于免疫力低下小鼠,BLTA100组和BLTA150组小鼠的生存率明显高于未处理组(P0.01)。无论免疫力正常还是免疫力低下小鼠,BLTA100组和BLTA150组的肾组织白色念珠菌菌落计数与未处理组比较均显著降低(P0.01)。结论 BLTA能够有效地改善深部白色念珠菌感染小鼠的生存状态,而且这种作用与BLTA呈剂量依赖关系。     

31P-NMR studies of the oral pathogen Streptococcus mutans: Observation of lipoteichoic acid

We have used ³¹P-nuclear magnetic resonance spectroscopy to identify phosphorus-containing compounds in whole cells of two serotype c strains of the oral pathogen Streptococcus mutans. The major resonance, centered at 0 ppm in whole cells, was attributed to lipoteichoic acid on the basis of its chemical shift, insensitivity to pH changes, cellular localization and a comparison with spectra obtained with purified lipoteichoic acid from S. mutans. The linewidths of resonances observed for intact cells and purified lipoteichoic acid were moderately narrowed by increasing the ionic strength, and substantially broadened in the presence of the lectin concanavalin A. Experiments with purified lipoteichoic acid suggest that this compound in whole cells is complexed with divalent cations such as Mg²⁺. Intracellular pools of other phosphorus-containing metabolites were found to be low when compared to the lipoteichoic acid concentration in both starved and glycolyzing cells.     

Triton X-100-induced lipoteichoic acid release is correlated with the methicillin resistance in Staphylococcus aureus

We previously reported that Triton X-100 (TRX) reduced methicillin resistance in Staphylococcus aureus, although the degree of reduction varied among strains. One of the biological effects of TRX on S. aureus cells was enhancement of lipoteichoic acid (LTA) release. We investigated the correlation between the amount of LTA released and the degree of reduction in methicillin resistance induced by TRX. The strains showing the greatest reduction of methicillin resistance released the largest amount of LTA, compared to those showing slight or moderate reduction. A mutant whose resistance was not affected by TRX did not increase its release of LTA. These findings suggest that LTA release is associated with a reduction in methicillin resistance in the presence of TRX.     

Butanol-extracted lipoteichoic acid induces in vivo leukocyte adhesion

Lipoteichoic acid (LTA), an immunostimulatory component of the cell walls of Gram positive bacteria, has pro-inflammatory effects in vitro and in vivo. However, one in vivo study concluded that LTA had no noticeable effects on leukocyte recruitment. In this study we investigated the effects of highly purified LTA, prepared by butanol extraction (Bu-LTA) at room temperature, on in vivo leukocyte adhesion. Using intravital microscopy we measured adhesion of leukocytes in mesenteric post-capillary venules of rats and mice. Topical superfusion of Bu-LTA (1 μg/ml) in rats significantly (p < 0.05) increased adhesion within 30 min. By contrast, hot phenol-extracted LTA did not increase adhesion. Alkaline hydrolysis of Bu-LTA removed alanine residues and prevented adhesion. Also, pre-administration of anti-rat β₂-integrin antibody abolished Bu-LTA-induced adhesion. Finally, intraperitoneal injection of Bu-LTA (100 μg/ml) into mice also significantly (p < 0.01) increased leukocyte adhesion measured at 60 min. In conclusion, Bu-LTA with intact alanine residues promotes β₂-integrin-dependent leukocyte adhesion in vivo.