ICAM-1 depletion in the center of immunological synapses is important for calcium releasing in T-cells

T-cell activation requires the formation of the immunological sy napse(IS)bet ween a T-cll and anantigen-presenting cell(AP C)to control the development of the adaptive immune response.How-ever,calcium release,an initial signal of T-cell activation,has been found to occur before IS for-mation.The mechanism for triggering the calcium signaling and relationship bet ween calciumrelease and IS format ion remains unclear.Herein,using live-cell imaging,we found that int ercellularadhesion molecule 1(ICAM-1),an essential mdlecule for IS formation,accumulated and then wasdepleted at the center of the synapse before complete IS formation.During the proces of ICAM1depletion,calcium was released.if ICAM-1 failed to be depleted from the center of the synapse,thesustained calcium signaling could not be induced.Moreover,depletion of ICAM-1 in ISs preferen-tially ccurred with the contact of antigen-specific T-cels and dendritic clls(DCs).Blocking thebinding ofICA M-1 and lymphocy te finction-associated antigen 1(LFA-1),ICAM-1 failed to depleteat the center of the synapse,and calcium release in T-clls decreased.In studying the mechanism ofhow the depletion ofiCA M1 could influence calcium release in T-clls,we found that the movementof ICAM-1 was associat ed with the localization of LFA-1 in the IS,which afected the localization ofcalcium microdomains,ORAIl and mitochondria in IS.Therefore,the depletion of ICAM-1 in the center of the synapse is an important factor for an initial sust ained calcium release in T-cells.

Cross-neutralization of SARS coronavirus-specific antibodies against bat SARS-like coronaviruses

Dear Editor,The 2002–2003 global pandemic caused by severe acute respiratory syndrome coronavirus(SARS-CoV)infected around 8,000 people with 10%mortality(http://www.who.int/csr/sars/en/).The virus has a positivestranded RNA genome that encodes a large polyprotein(1a and 1ab),four structural proteins,including spike(S),

Sin1/mTORC2 regulate B cell growth and metabolism by activating mTORC1 and Myc

Proper control of B cell growth and metabolism is crucial for B-cell-mediated immunity,but the underlying molecular mechanisms remain incompletely understood.In this study,Sin1,a key component of mTOR complex 2(mTORC2),specifically regulates B cell growth and metabolism.Genetic ablation of Sin1 in B cells reduces the cell size at either the transitional stage or upon antigen stimulation and severely impairs metabolism.Sin1 deficiency also severely impairs B-cell proliferation,antibody responses,and anti-viral immunity.At the molecular level,Sin1 controls the expression and stability of the c-Myc protein and maintains the activity of mTORC1 through the Akt-dependent inactivation of GSK3 and TSC1/2,respectively.Therefore,our study reveals a novel and specific role for Sin1 in coordinating the activation of mTORC2 and mTORC1 to control B cell growth and metabolism.

The development of HIV vaccines targeting gp41 membrane-proximal external region （MPER）： challenges and prospects

A human immunodeficiency virus type-1 （HIV-1） vaccine which is able to effectively prevent infection would be the most powerful method of extinguishing pandemic of the acquired immunodeficiency syndrome （AIDS）. Yet, achieving such vaccine remains great challenges. The membrane-proximal external region （MPER） is a highly conserved region of the envelope glycoprotein （Env） gp41 subunit near the viral envelope surface, and it plays a key role in membrane fusion. It is also the target of some reported broadly neutralizing antibodies （bNAbs）. Thus, MPER is deemed to be one of the most attractive vaccine targets. However, no one can induce these bNAbs by immunization with immunogens con- taining the MPER sequence（s）. The few attempts at developing a vaccine have only resulted in the induction of neutralizing antibodies with quite low potency and limited breadth. Thus far, vaccine failure can be attrib- uted to various characteristics of MPER, such as those involving structure and immunology; therefore, we will focus on these and review the recent progress in the field from the following perspectives： （1） MPER structure and its role in membrane fusion, （2） the epitopes and neutralization mechanisms of MPER-specific bNAbs, as well as the limitations in eliciting neutralizing antibodies, and （3） different strategies for MPER vaccine design and current harvests.

Modulation of host signaling in the inflammatory response by enteropathogenic Escherichia coli virulence proteins

To successfully infect host cells and evade the host immune response, a type III secretion system （T3SS） is commonly used by enteric bacterial pathogens such as enteropathogenic Escherichia coil （EPEC）. Recent findings have revealed that various effectors are injected into host cells through the T3SS and exert an inhibitory effect on inflammatory signaling pathways, subverting the immune responses to these pathogens. Here we review recent studies aimed at addressing the modulation of several important inflammatory signaling pathways modulated by EPEC effector proteins, such as the nuclear factor-KB （NF-KB） and mitogen-activated protein kinase （MAPK） pathways, which provides insight into the unfinished work in this unexplored field and helps to identify novel positions in inflammatory signaling networks for EPEC effectors.

Seeking "protective" and "harmful" immune genes during chronic HIV-1 infection by transcriptome analysis

Human immunodeficiency virus(HIV)-infected individuals exhibit remarkable transcriptomic variation.Transcriptome analyses of antiretroviral therapy(ART)-free chronically infected HIV-1 patients with different clinical outcomes are likely to aid the development of vaccine and immune therapies.Here,we performed microarray analyses on whole-blood derived RNA from 89 ART-free HIV-1-infected individuals from 2 cohorts.The differentially expressed genes were analyzed between long-term non-progressors,viremic non-progressors and typical progressors,and between elite controllers and non-elite controllers among the long-term nonprogressors.Several genes related to T-cell growth,proliferation and differentiation and antiapoptosis were upregulated,whereas interferon-stimulated genes and inflammatory genes were significantly downregulated in long-term non-progressors and viremic non-progressors.The observations above were further confirmed in the set of 261 genes that correlated with disease progression during a 5-year follow-up,which included 51 genes significantly associated with slower disease progression,and 210 genes associated with aggressive disease progression.Overall,our data suggest that it is vital to maintain the homeostasis of the immune system when mounting antiviral immune responses.Immune therapeutics able to reconstruct immune homeostasis are likely to be required for immune reconstitution in the context of ART,such as the administration of interleukin-7,healthy allogenic CD4^(+)T cells(providing CD4^(+)T-cell growth factors),or Tregs.