Altered surface expression of effector cell molecules on neutrophils in myelodysplastic syndromes

The surface expression of effector cell molecules on neutrophils was examined in 18 patients with myelodysplastic syndromes (MDS) and 20 healthy control subjects. The MDS patients were further classified as low clinical risk (L-MDS, n  = 7) and high clinical risk (H-MDS, n  = 11). The expression of Fc receptors for IgG (FcR), complement receptors (CR) and cellular adhesion molecules on neutrophils was determined by flow cytometry and monoclonal antibodies. The effect of granulocyte colony-stimulating factor (G-CSF) and tumour necrosis factor-alpha (TNF) on L-selectin shedding and CR up-regulation on neutrophils was also examined. The percentage of FcRI-positive neutrophils and CD11b/CR3 expression on neutrophils were significantly increased in the H-MDS patients when compared to the controls. In contrast, the expression of FcRII, FcRIII, L-selectin, LFA-1 and CD18 on neutrophils was significantly reduced in the H-MDS patients compared with the controls. The L-MDS neutrophils exhibited lower expressions of CR1, L-selectin, LFA-1 and CD18 than those of the controls. Neutrophils from some H-MDS patients showed impaired L-selectin shedding and CR up-regulation after stimulation with G-CSF or TNF, although these were not significantly different when assessed in the whole H-MDS group. These findings suggest that an altered surface expression of effector cell molecules and an impaired modulation of cellular adhesion molecules on neutrophils may contribute to the increased susceptibility to bacterial infections in MDS patients.     

Origin of CD8^＋ Effector and Memory T Cell Subsets

It is well accepted that CD8＋ T cells play a pivotal role in providing protection against infection with intracellular pathogens and some tumors. In many cases protective immunity is maintained for long periods of time （immunological memory）. Over the past years, it has become evident that in order to fulfill these multiple tasks, distinct subsets of effector and memory T cells have to be generated. Until today, however, little is known about the underlying mechanisms of subset differentiation and the timing of lineage fate decisions. In this context, it is of special importance to determine at which level of clonal expansion functional and phenotypical heterogeneity is achieved. Different models for T cell subset diversification have been proposed; these differ mainly in the time point during priming and clonal expansion （prior, during, or beyond the first cell division） when differentiation programs are induced. Recently developed single-cell adoptive transfer technology has allowed us to demonstrate that individual precursor cell still bears the full plasticity to develop into a plethora different T cell subsets. This observation targets the shaping of T cell subset differentiation towards factors that are still operative beyond the first cell division. These findings have important implications for vaccine development, as the modulation of differentiation patterns towards distinct subsets could become a powerful strategy to enhance the efficacy and quality of vaccines. Cellular ＆ Molecular Immunology.     

Transanal Transection and Single-Stapled Anastomosis (TTSS): A comparison of anastomotic leak rates with the double-stapled technique and with transanal total mesorectal excision (TaTME) for rectal cancer

Backgroundin the literature on rectal cancer (RC) surgery many studies have focused on the quality of total mesorectal excision (TME) dissection, while there is a scarcity of comparative data on transection and anastomosis. No anastomosis has so far proved to be superior to any other. The aim of this study was to compare anastomotic leak (AL) rates between conventional laparoscopic double-stapled (DS), transanal total mesorectal excision (TaTME) and Transanal Transection and Single-Stapled anastomosis (TTSS) techniques.Methodsconsecutive mid-low RC patients undergoing elective laparoscopic TME with stapled anastomosis and protective stoma, by either DS, TaTME or TTSS techniques were retrieved from a prospectively collected database.Results127 DS; 100 TaTME and 50 TTSS were included. Demographics, distance of the tumor from anal verge and neoadjuvant therapy were comparable. Operative time was longer in TaTME over DS and TTSS (p < 0.0001). More 90-days complications occurred in DS group vs TTSS (p = 0.029). The AL rate was 17.5% in DS, 6% in TaTME and 2% in TTSS group (p = 0.005). AL grade was: one B (2%) in TTSS; 2 grade B (2%) and 4 grade C (4%) in TaTME; 6 grade A (4.7%), 7 grade B (5.5%) and 9 grade C (7.1%) in DS group. Reintervention rate after AL was higher in DS group over TTSS (12.6% vs 2%; p = 0.003). The rate of stoma closure, pathology data and margin positivity did not differ.ConclusionsTTSS strategy is feasible, safe and leads to very low AL rates after TME for RC.     

The role of Fc receptors in HIV prevention and therapy

Over the past decade, a wealth of experimental evidence has accumulated supporting the importance of Fc receptor (FcR) ligation in antibody-mediated pathology and protection in many disease states. Here we present the diverse evidence base that has accumulated as to the importance of antibody effector functions in the setting of HIV prevention and therapy, including clinical correlates, genetic associations, viral evasion strategies, and a rapidly growing number of compelling animal model experiments. Collectively, this work identifies antibody interactions with FcR as important to both therapeutic and prophylactic strategies involving both passive and active immunity. These findings mirror those in other fields as investigators continue to work toward identifying the right antibodies and the right effectors to be present at the right sites at the right time.     

Initial viral load determines the magnitude of the human CD8 T cell response to yellow fever vaccination

CD8 T cells are a potent tool for eliminating intracellular pathogens and tumor cells. Thus, eliciting robust CD8 T-cell immunity is the basis for many vaccines under development. However, the relationship between antigen load and the magnitude of the CD8 T-cell response is not well-described in a human immune response. Here we address this issue by quantifying viral load and the CD8 T-cell response in a cohort of 80 individuals immunized with the live attenuated yellow fever vaccine (YFV-17D) by sampling peripheral blood at days 0, 1, 2, 3, 5, 7, 9, 11, 14, 30, and 90. When the virus load was below a threshold (peak virus load < 225 genomes per mL, or integrated virus load < 400 genome days per mL), the magnitude of the CD8 T-cell response correlated strongly with the virus load (R² ∼ 0.63). As the virus load increased above this threshold, the magnitude of the CD8 T-cell responses saturated. Recent advances in CD8 T-cell–based vaccines have focused on replication-incompetent or single-cycle vectors. However, these approaches deliver relatively limited amounts of antigen after immunization. Our results highlight the requirement that T-cell–based vaccines should deliver sufficient antigen during the initial period of the immune response to elicit a large number of CD8 T cells that may be needed for protection.CD8 T cells provide a powerful mechanism for elimination of intracellular pathogens and tumor cells. Accordingly, a major thrust of current vaccine research focuses on stimulating robust T-cell immunity for defense against infections such as HIV, malaria, tuberculosis, Ebola virus, herpes viruses, and hepatitis C virus (HCV) (1–8). Inducing effective CD8 T-cell immunity is also an important goal for cancer vaccines (9, 10). However, how antigen load affects the CD8 T-cell response has not been quantified in a detailed manner during a human immune response. In this study we address this question using the human live attenuated yellow fever vaccine (YFV-17D) vaccine.The dynamics of CD8 T-cell responses to intracellular infection have been extensively studied in model systems. Infection typically stimulates a rapid burst of proliferation in antigen-specific CD8 T cells with division occurring as quickly as once in 4–6 h (11). This expansion results in a large population of effector CD8 T cells that aid in clearance of infected cells. Although most (90–95%) of the effector CD8 T cells die, a small fraction differentiate to form long-term memory CD8 T cells (12). Detailed quantitative measurements of the dynamics of virus and the CD8 T-cell response to the YFV-17D vaccine allow us to characterize these basic features of the CD8 T-cell responses in humans. Additionally, tracking the dynamics of both virus and CD8 T cells over time in a large cohort allows us to explore the relationship between amount of antigen and the magnitude of expansion and answer the following questions: Is there a threshold amount of virus required to generate a response? Does the magnitude of the response increase proportionally, or does it saturate with viral load? Although a number of studies have considered the complex relationship between numbers of specific CD8 T cells and virus loads during the chronic phase of HIV and HCV infections (3, 13–23), very few studies (24–27) have investigated these questions in the context of the generation of immune response following acute infections and vaccination.We addressed these questions by measuring the dynamics of both virus and virus-specific CD8 T cells following immunization with the YFV-17D vaccine. The YFV-17D vaccine comprises a highly efficacious, live attenuated virus that causes an acute infection and stimulates a robust immune response conferring lifelong protection against the yellow fever virus (YFV) (28, 29). Because yellow fever is not endemic to the United States, immunization with YFV-17D induces a primary immune response (30, 31). Previous work with YFV-17D has identified CD8 T cells specific for some of the YFV epitopes and defined the stages of expansion, contraction, and memory maintenance (32–38). We now know that YFV stimulates a polyfunctional, broadly targeting, and long-lasting CD8 T-cell response. Of particular note, we have previously demonstrated that the magnitude of the total effector CD8 T-cell response against YFV can be measured using the Ki-67⁺ Bcl-2^lo HLA-DR⁺ CD38⁺ phenotype of activated T cells seen early after vaccination (38). In the current study, we followed a large cohort of 80 individuals with intensive sampling at days 0, 1, 2, 3, 5, 7, 9, 11, 14, 30, and 90 postvaccination to quantify viral load in plasma (39). Additionally, we quantified the magnitude of the YFV-specific effector CD8 T-cell response at days 0, 3, 7, 14, 30, and 90 postvaccination using the Ki-67⁺Bcl-2^lo phenotype. We find that different individuals have different virus loads following infection and generate CD8 T-cell responses of different sizes. This allows us to determine the relationship between virus load and magnitude of the CD8 T-cell response.The majority of vaccines that are currently under development use replication-incompetent or single-cycle vectors such as Modified Vaccinia Ankara, adenovirus, and DNA. Although these approaches are inherently safe, they may express and deliver relatively limited amounts of antigen. Our results emphasize the requirement that T-cell–based vaccines deliver sufficient antigen to elicit a large CD8 T-cell response that may be needed for protection.     

Vibrio parahaemolyticus orchestrates a multifaceted host cell infection by induction of autophagy, cell rounding, and then cell lysis

The bacterial pathogen Vibrio parahaemolyticus utilizes a type III secretion system to cause death of host cells within hours of infection. We report that cell death is completely independent of apoptosis and occurs by a mechanism in which injection of multiple type III effectors causes induction of autophagy, cell rounding, and the subsequent release of cellular contents. Autophagy is detected by the appearance of lipidated light chain 3 (LC3) and by increases in punctae and vacuole formation. Electron microscopy reveals the production of early autophagic vesicles during infection. Consistent with phosphoinositide 3 (PI3) kinase playing a role in autophagy, treatment of infected cells with a PI3 kinase inhibitor attenuates autophagy in infected cells. Because many effectors are injected during a V. parahaemolyticus infection, it is not surprising that the presence of a sole PI3 kinase inhibitor does not prevent inevitable host-cell death. Our studies reveal an infection paradigm whereby an extracellular pathogen uses its type III secretion system to cause at least three parallel events that eventually result in the proinflammatory death of an infected host cell.     

慢性乙型肝炎患者外周血CD8^＋T细胞亚群分布和PD-1表达特征研究

目的分析慢性乙型肝炎（CHB）患者外周血中CD8^＋T细胞及其亚群表面程序性死亡受体-1（PD-1）表达的变化特征及其临床关联性。方法用流式细胞术检测14例CHB患者和15例健康对照者外周血中CD8^＋T细胞及其亚群初始T细胞（TN）、中央记忆T细胞（TCM）、效应记忆T细胞（TEM）、终末效应记忆T细胞（TEMRA）的频数及细胞表面PD-1的表达水平,同时收集患者一般资料、生化指标和乙型肝炎病毒（HBV）病毒学指标等临床资料。使用SAS 9.1统计软件分析数据,应用Mann-Whitney U test分析组间差异,应用Spearman秩相关进行相关性分析,P〈0.05为差异有统计学意义。结果与健康对照组相比,CHB患者的TEMRA亚群在CD8^＋T细胞中的频数显著降低（P=0.012）,总CD8^＋T细胞（P=0.018）及其TEM亚群（P=0.004）表面PD-1的表达水平显著上升。相关性研究显示,CD8^＋TEM细胞表面PD-1的表达水平与HBV DNA载量呈显著正相关（r=0.554,P=0.040）。结论 CHB患者外周血中PD-1阳性的CD8^＋TEM频数升高,且与外周血中HBV DNA载量呈正相关,提示慢性乙型肝炎患者机体内HBV复制的活跃性可能与外周血中CD8^＋T细胞的活化状态,特别是其TEM亚群上PD-1的高表达关联。