Immunological mechanisms of fecal microbiota transplantation in recurrent Clostridioides difficile infection

Fecal microbiota transplantation (FMT) is a successful method for treating recurrent Clostridioides difficile (C. difficile) infection (rCDI) with around 90% efficacy. Due to the relative simplicity of this approach, it is being widely used and currently, thousands of patients have been treated with FMT worldwide. Nonetheless, the mechanisms underlying its effects are just beginning to be understood. Data indicate that FMT effectiveness is due to a combination of microbiological direct mechanisms against C. difficile, but also through indirect mechanisms including the production of microbiota-derived metabolites as secondary bile acids and short chain fatty acids. Moreover, the modulation of the strong inflammatory response triggered by C. difficile after FMT seems to rely on a pivotal role of regulatory T cells, which would be responsible for the reduction of several cells and soluble inflammatory mediators, ensuing normalization of the intestinal mucosal immune system. In this minireview, we analyze recent advances in these immunological aspects associated with the efficacy of FMT.     

Extended protection capabilities of an immature dendritic-cell targeting malaria sporozoite vaccine

Mouse studies evaluating candidate malaria vaccines have typically examined protective efficacy over the relatively short time frames of several weeks after the final of multiple immunizations. The current study examines the protective ability in a mouse model system of a novel protein vaccine construct in which the adjuvant polyinosinic polycytidilic acid (poly(I:C)) is used in combination with a vaccine in which the immature dendritic cell targeting chemokine, macrophage inflammatory protein 3 alpha (MIP3α), is fused to the circumsporozoite protein (CSP) of Plasmodium falciparum (P. falciparum). Two vaccinations, three weeks apart, elicited extraordinarily high, MIP3α-dependent antibody responses. MIP3α was able to target the vaccine to the CCR6 receptor found predominantly on immature dendritic cells and significantly enhanced the cellular influx at the vaccination site. At three and 23 weeks after the final of two immunizations, mice were challenged by intravenous injection of 5 × 10³ transgenic Plasmodium berghei sporozoites expressing P. falciparum CSP, a challenge dose approximately one order of magnitude greater than that which is encountered after mosquito bite in the clinical setting. A ninety-seven percent reduction in liver sporozoite load was observed at both time points, 23 weeks being the last time point tested.     

炎症性肠病发病机制新进展

炎症性肠病（IBD）的病因和发病机制至今仍未完全明确。近年研究认为其发病与免疫、遗传、环境、微生物等因素均有着密切的联系。本文对近年IBD发病机制研究的新进展，包括IBD的易感基因、环境因素对IBD的影响、宿主防御反应与肠道菌群的相互作用以及IBD的肠黏膜屏障和内环境、先天性免疫和获得性免疫情况作一综述。     

海珠益肝胶囊对小鼠免疫性肝损伤的影响

目的:进一步证实海珠益肝胶囊对肝损伤小鼠的保肝降酶作用。方法:来用卡介苗 脂多糖(BCG LPS)造成免疫性肝损伤模型小鼠,观察本品对血清中ALT、AST活力单位、肝脾脏器系数和肝脏病理组织学损伤程度的影响。结果:药物能降低血清中ALT、AST活力单位(P<0.01);减小肝脾肿大及脏器系数(P<0.01);减轻肝组织病理损伤程度。结论:海珠益肝胶囊对BCG LPS所致肝损伤小鼠有明显保肝降酶作用。     

Alterations of intestinal immune function and regulatory effects of L-arginine in experimental severe acute pancreatitis rats

ABM: To discuss the changes of intestinal mucosal immune function in rats with experimental severe acute pancreatitis (SAP) and the regulatory effect of L-arginine. METHODS: Male adult Wistar rats were randomly divided into pancreatitis group, sham-operation group, and L-arginine treatment group. Animals were killed at 24, 48, and 72 h after SAP models were developed and specimens were harvested. Endotoxin concentration in portal vein was determined by limulus endotoxin analysis kit. CD3+, CD4+, CD8+ T lymphocytes in intestinal mucosal lamina propria were examined by immunohistochemistry. Secretory immunoglobulin A (SIgA) in cecum feces was examined by radioimmunoassay. RESULTS: Compared to the control group, plasma endotoxin concentration in the portal vein increased, percentage of CD3+ and CD4+ T lymphocyte subsets in the end of intestinal mucosal lamina propria reduced significantly, CD4+/CD8+ ratio decreased, and SIgA concentrations in cecum feces reduced at 24, 48, and 72 h after SAP developed. Compared to SAP group, the L-arginine treatment group had a lower level of plasma endotoxin concentration in the portal vein, a higher CD3+ and CD4+ T lymphocyte percentage in the end of intestinal mucosal lamina propria, an increased ratio of CD4+/CD8+ and a higher SIgA concentration in cecum feces. CONCLUSION: Intestinal immune suppression occurs in the early stage of SAP rats, which may be the main reason for bacterial and endotoxin translocation. L-arginine can improve the intestinal immunity and reduce bacterial and endotoxin translocation in SAP rats.     

Blueprint for schistosomiasis vaccine development

A number of different schistosome antigens are capable of partially protecting experimental animals from challenge infection. More than 100 such antigens have been identified, about 15% of which are strongly protective and deemed promising though they do not reach the level close to sterile immunity seen after vaccination with irradiated cercariae. Studies of human correlate reactions, i.e. serological reactions and cytokine responses to schistosomiasis antigens, in individuals living in areas endemic for schistosomiasis have shown associations between certain antigen-specific immune responses and lack of re-infection over time. This approach was applied in Brazil and Egypt where it was possible to epidemiologically follow cohorts of individuals in endemic areas for extended periods of time correlating infection status with immune responses against a panel of well-researched, highly purified vaccine candidates. The immune correlates found were unique to each antigen and could be either positive or negative, i.e. associated with resistance or with susceptibility to re-infection. However, few antigens were clear-cut in this respect, i.e. the majority of them induced ambiguous responses. For example, a single antigen might have a significant positive correlation when antigen-driven interferon (INF)-gamma production is measured but also show a significant negative correlation with respect to the IgG1 titre induced. These observations suggest that there are desirable, antigen-specific immune responses that would be valuable in a vaccine but they also indicate that there are responses that must be avoided. The insights gained should be useful not only for antigen selection but also for vaccine formulation prior to Phase I/II trials in humans. It would be of great value if similar independent, long-term human correlate studies could also be undertaken in areas endemic for Schistosoma japonicum.     

Live porcine reproductive and respiratory syndrome virus vaccines: Current status and future direction

Porcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) was reported in the late 1980s. PRRS still is a huge economic concern to the global pig industry with a current annual loss estimated at one billion US dollars in North America alone. It has been 20 years since the first modified live-attenuated PRRSV vaccine (PRRSV-MLV) became commercially available. PRRSV-MLVs provide homologous protection and help in reducing shedding of heterologous viruses, but they do not completely protect pigs against heterologous field strains. There have been many advances in understanding the biology and ecology of PRRSV; however, the complexities of virus-host interaction and PRRSV vaccinology are not yet completely understood leaving a significant gap for improving breadth of immunity against diverse PRRS isolates. This review provides insights on immunization efforts using infectious PRRSV-based vaccines since the 1990s, beginning with live PRRSV immunization, development and commercialization of PRRSV-MLV, and strategies to overcome the deficiencies of PRRSV-MLV through use of replicating viral vectors expressing multiple PRRSV membrane proteins. Finally, powerful reverse genetics systems (infectious cDNA clones) generated from more than 20 PRRSV isolates of both genotypes 1 and 2 viruses have provided a great resource for exploring many innovative strategies to improve the safety and cross-protective efficacy of live PRRSV vaccines. Examples include vaccines with diminished ability to down-regulate the immune system, positive and negative marker vaccines, multivalent vaccines incorporating antigens from other porcine pathogens, vaccines that carry their own cytokine adjuvants, and chimeric vaccine viruses with the potential for broad cross-protection against heterologous strains. To combat this devastating pig disease in the future, evaluation and commercialization of such improved live PRRSV vaccines is a shared goal among PRRSV researchers, pork producers and biologics companies.     

甘草酸在肝外疾病中的研究进展

异甘草酸镁是常用的护肝降酶药物,其主要成分由甘草酸制备而得,后者具有抗炎、抗氧化、抗病毒感染的作用。近年研究证实,甘草酸可能对缺血-再灌注损伤、神经系统损伤、多种炎症、免疫相关疾病、内分泌疾病和肿瘤有治疗作用,有广阔的应用前景。本文系统总结近年来甘草酸在肝外疾病中的研究进展,概括甘草酸治疗上述疾病的可能机制,并对未来的研究方向做前瞻性的展望。     

前S2合成肽对肝癌组织中浸润T淋巴细胞亚群表达的影响

目的通过前S2合成肽对肝细胞癌(HCC)组织中浸润T淋巴细胞亚群表达状况的分析,探讨前S2合成肽是否能改变乙型肝炎病毒(HBV)导致的HCC组织中浸润T淋巴细胞亚群表达的百分数和CD4+/CD8+比值,达到特异性治疗HCC. 方法用Merrifield固相化学合成法合成HBV中前S2抗原性最强的P120～146多肽段.测序后,用0.01mol/L磷酸盐缓冲液溶解除菌后作为抗原.选择12例术后病理诊断为HCC,术前血清经酶联免疫吸附法测得HBsAg、HBeAg、抗-HBC阳性和HBV DNA阳性,且HBsAg在HCC组织中表达为阳性病例作为研究对象.在96孔培养板上,每孔加入经密梯度离心获得的单个核细胞悬液100μl(1×106细胞),设每孔含量为1μg、5μg、10μg、白细胞介素-2 500U和阴性对照共5组,每组均设3复孔,作用7d后制片,采用APAAP法观察CD3+、CD4+、CD8+的百分数和CD4+/CD8+的比值变化. 结果 发现在含有前S2合成肽5μg/孔组中,CD4+表达明显增加(34.1±3.2),与自身对照(29.3±3.5)相比差异有显著性 (t＝3.508,P<0.01),CD4+/CD8+比值(1.19±0.43)与自身对照(0.81±0.41)相比差异有显著性(t＝2.235,P＜0.05).在白细胞介素-2组中,CD3+表达有增加,与自身对照相比有差异,其它各组T淋巴细胞亚群几乎处于不变化的状态. 结论在适当的剂量下,前S2合成肽能够改变HCC组织中T淋巴细胞亚群的表达,使CD4+增加,并能改变CD8+静息状态,使二者互为达到杀伤肿瘤细胞的目的,为特异性运用前S2蛋白提供客观依据.     

Immune responses of poultry to Newcastle disease virus

Newcastle disease (ND) remains a constant threat to poultry producers worldwide, in spite of the availability and global employment of ND vaccinations since the 1950s. Strains of Newcastle disease virus (NDV) belong to the order Mononegavirales, family Paramyxoviridae, and genus Avulavirus, are contained in one serotype and are also known as avian paramyxovirus serotype-1 (APMV-1). They are pleomorphic in shape and are single-stranded, non-segmented, negative sense RNA viruses. The virus has been reported to infect most orders of birds and thus has a wide host range. Isolates are characterized by virulence in chickens and the presence of basic amino acids at the fusion protein cleavage site. Low virulent NDV typically produce subclinical disease with some morbidity, whereas virulent isolates can result in rapid, high mortality of birds. Virulent NDV are listed pathogens that require immediate notification to the Office of International Epizootics and outbreaks typically result in trade embargos. Protection against NDV is through the use of vaccines generated with low virulent NDV strains. Immunity is derived from neutralizing antibodies formed against the viral hemagglutinin and fusion glycoproteins, which are responsible for attachment and spread of the virus. However, new techniques and technologies have also allowed for more in depth analysis of the innate and cell-mediated immunity of poultry to NDV. Gene profiling experiments have led to the discovery of novel host genes modulated immediately after infection. Differences in virus virulence alter host gene response patterns have been demonstrated. Furthermore, the timing and contributions of cell-mediated immune responses appear to decrease disease and transmission potential. In view of recent reports of vaccine failure from many countries on the ability of classical NDV vaccines to stop spread of disease, renewed interest in a more complete understanding of the global immune response of poultry to NDV will be critical to developing new control strategies and intervention programs for the future.