Blood-brain barrier (BBB) breakdown and immune cell infiltration into the central nervous system (CNS) are early hallmarks of multiple sclerosis (MS). High numbers of CD8
T cells are found in MS ...lesions, and antigen (Ag) presentation at the BBB has been proposed to promote CD8
T cell entry into the CNS. Here, we show that brain endothelial cells process and cross-present Ag, leading to effector CD8
T cell differentiation. Under physiological flow in vitro, endothelial Ag presentation prevented CD8
T cell crawling and diapedesis resulting in brain endothelial cell apoptosis and BBB breakdown. Brain endothelial Ag presentation in vivo was limited due to Ag uptake by CNS-resident macrophages but still reduced motility of Ag-specific CD8
T cells within CNS microvessels. MHC class I-restricted Ag presentation at the BBB during neuroinflammation thus prohibits CD8
T cell entry into the CNS and triggers CD8
T cell-mediated focal BBB breakdown.
Antigen cross-presentation by dendritic cells (DC) stimulates cytotoxic T cell activation to promote immunity to intracellular pathogens, viruses and cancer. Phagocytosed antigens generate potent T ...cell responses, but the signalling and trafficking pathways regulating their cross-presentation are unclear. Here, we show that ablation of the store-operated-Ca
-entry regulator STIM1 in mouse myeloid cells impairs cross-presentation and DC migration in vivo and in vitro. Stim1 ablation reduces Ca
signals, cross-presentation, and chemotaxis in mouse bone-marrow-derived DCs without altering cell differentiation, maturation or phagocytic capacity. Phagosomal pH homoeostasis and ROS production are unaffected by STIM1 deficiency, but phagosomal proteolysis and leucyl aminopeptidase activity, IRAP recruitment, as well as fusion of phagosomes with endosomes and lysosomes are all impaired. These data suggest that STIM1-dependent Ca
signalling promotes the delivery of endolysosomal enzymes to phagosomes to enable efficient cross-presentation.
Macroautophagy was recently shown to regulate both lymphocyte biology and innate immunity. In this study we sought to determine whether a deregulation of autophagy was linked to the development of ...autoimmunity. Genome-wide association studies have pointed out nucleotide polymorphisms that can be associated with systemic lupus erythematosus, but the potential role of autophagy in the initiation and/or development of this syndrome is still unknown. Here, we provide first clues of macroautophagy deregulation in lupus. By the use of LC3 conversion assays and electron microscopy experiments, we observed that T cells from two distinct lupus-prone mouse models, i.e., MRL
lpr/lpr
and (NZB/NZW)F1, exhibit high loads of autophagic compartments compared with nonpathologic control CBA/J and BALB/c mice. Unlike normal mice, autophagy increases with age in murine lupus. In vivo lipopolysaccharide stimulation in CBA/J control mice efficiently activates T lymphocytes but fails to upregulate formation of autophagic compartments in these cells. This argues against a deregulation of autophagy in lupus T cells solely resulting from an acute inflammation injury. Autophagic vacuoles quantified by electron microscopy are also found to be significantly more frequent in T cells from lupus patients compared with healthy controls and patients with non-lupus autoimmune diseases. This elevated number of autophagic structures is not distributed homogeneously and appears to be more pronounced in certain T cells. These results suggest that autophagy could regulate the survival of autoreactive T cell during lupus, and could thus lead to design new therapeutic options for lupus.
The nuclear translocation of endogenous heat shock cognate protein HSPA8 is a requisite for cell survival during oxidative and heat shock stress. Upon these events, cytoplasmic HSPA8 is thought to ...concentrate within the nucleus and nucleolus. When the situation returns to normal, HSPA8 is released from its nuclear/nucleolar anchors and redistributes into the cytoplasm. By using different stress conditions and a 21-mer phosphopeptide tool called P140, which binds HSPA8 and hampers its chaperone properties, we deciphered the cellular and molecular effects arising during this vital cytoplasmic-nuclear-cytoplasmic shuttling process. Using the non-metastatic fibroblastoid cell line MRL/N-1 derived from a MRL/MpTn-gld/gld lupus-prone mouse, we discovered that P140 treatment neutralized the egress of HSPA8 from nucleus to cytoplasm in the cell recovery phase. This lack of relocation of HSPA8 into the cytoplasm of heat-shocked MRL/N-1 cells altered the ability of these cells to survive when a second mild oxidative stress mimicking inflammatory conditions was applied. Crosslinking experiments followed by proteomics studies showed that P140 binds regions close to nuclear import and export signal sequences encompassed within the HSPA8 structure. These data are consistent with HSPA8 having a crucial cell protective role against reactive oxygen species (ROS) production by mitochondria during inflammatory conditions.
Self-reactive CD8
T cells are important mediators of progressive tissue damage in autoimmune diseases, but the molecular program underlying these cells' functional adaptation is unclear. Here we ...characterize the transcriptional and epigenetic landscape of self-reactive CD8
T cells in a mouse model of protracted central nervous system (CNS) autoimmunity and compare it to populations of CNS-resident memory CD8
T cells emerging from acute viral infection. We find that autoimmune CD8
T cells persisting at sites of self-antigen exhibit characteristic transcriptional regulation together with distinct epigenetic remodeling. This self-reactive CD8
T cell fate depends on the transcriptional regulation by the DNA-binding HMG-box protein TOX which remodels more than 400 genomic regions including loci such as Tcf7, which is central to stemness of CD8
T cells. Continuous exposure to CNS self-antigen sustains TOX levels in self-reactive CD8
T cells, whereas genetic ablation of TOX in CD8
T cells results in shortened persistence of self-reactive CD8
T cells in the inflamed CNS. Our study establishes and characterizes the genetic differentiation program enabling chronic T cell-driven immunopathology in CNS autoimmunity.
Viral infections lead to alarmin release and elicit potent cytotoxic effector T lymphocyte (CTL
) responses. Conversely, the induction of protective tumour-specific CTL
and their recruitment into the ...tumour remain challenging tasks. Here we show that lymphocytic choriomeningitis virus (LCMV) can be engineered to serve as a replication competent, stably-attenuated immunotherapy vector (artLCMV). artLCMV delivers tumour-associated antigens to dendritic cells for efficient CTL priming. Unlike replication-deficient vectors, artLCMV targets also lymphoid tissue stroma cells expressing the alarmin interleukin-33. By triggering interleukin-33 signals, artLCMV elicits CTL
responses of higher magnitude and functionality than those induced by replication-deficient vectors. Superior anti-tumour efficacy of artLCMV immunotherapy depends on interleukin-33 signalling, and a massive CTL
influx triggers an inflammatory conversion of the tumour microenvironment. Our observations suggest that replicating viral delivery systems can release alarmins for improved anti-tumour efficacy. These mechanistic insights may outweigh safety concerns around replicating viral vectors in cancer immunotherapy.
Objectives To identify common factors associated with post-neonatal, infant, child and under-5 mortality in Nigeria. Design, setting and participants A cross-sectional data of three Nigeria ...Demographic and Health Surveys (NDHS) for the years 2003, 2008 and 2013 were used. A multistage, stratified, cluster random sampling method was used to gather information on 63 844 singleton live-born infants of the most recent birth of a mother within a 5-year period before each survey was examined using cox regression models. Main outcome measures Postneonatal mortality (death between 1 and 11 months), infant mortality (death between birth and 11 months), child mortality (death between 12 and 59 months) and under-5 mortality (death between birth and 59 months). Results Multivariable analyses indicated that children born to mothers with no formal education was significantly associated with mortality across all four age ranges (adjusted HR=1.30, 95% CI 1.01 to 1.66 for postneonatal; HR=1.38, 95% CI 1.11 to 1.84 for infant; HR=2.13, 95% CI 1.56 to 2.89 for child; HR=1.19, 95% CI 1.02 to 1.41 for under-5). Other significant factors included living in rural areas (HR=1.48, 95% CI 1.16 to 1.89 for postneonatal; HR=1.23, 95% CI 1.03 to 1.47 for infant; HR=1.52, 95% CI 1.16 to 1.99 for child; HR=1.29, 95% CI 1.11 to 1.50 for under-5), and poor households (HR=2.47, 95% CI 1.76 to 3.47 for postneonatal; HR=1.40, 95% CI 1.10 to 1.78 for infant; HR=1.72, 95% CI 1.19 to 2.49 for child; HR=1.43, 95% CI 1.17 to 1.76 for under-5). Conclusions This study found that no formal education, poor households and living in rural areas increased the risk of postneonatal, infant, child and under-5 mortality among Nigerian children. Community-based interventions for reducing under-5 deaths are needed and should target children born to mothers of low socioeconomic status.
Commercial probiotic strains for food or supplement use can be altered in different ways for a variety of purposes. Production conditions for the strain or final product may be changed to address ...probiotic yield, functionality, or stability. Final food products may be modified to improve flavor and other sensory properties, provide new product formats, or respond to market opportunities. Such changes can alter the expression of physiological traits owing to the live nature of probiotics. In addition, genetic approaches may be used to improve strain attributes. This review explores whether genetic or phenotypic changes, by accident or design, might affect the efficacy or safety of commercial probiotics. We highlight key issues important to determining the need to re‐confirm efficacy or safety after strain improvement, process optimization, or product formulation changes. Research pinpointing the mechanisms of action for probiotic function and the development of assays to measure them are greatly needed to better understand if such changes have a substantive impact on probiotic efficacy.
T cell activation in lymphoid tissue occurs through interactions with cognate peptide-major histocompatibility complex (pMHC)-presenting dendritic cells (DCs). Intravital imaging studies using
...peptide-pulsed DCs have uncovered that cognate pMHC levels imprint a wide range of dynamic contacts between these two cell types. T cell-DC interactions vary between transient, "kinapse-like" contacts at low to moderate pMHC levels to immediate "synapse-like" arrest at DCs displaying high pMHC levels. To date, it remains unclear whether this pattern is recapitulated when the immune system faces a replicative agent, such as a virus, at low and high inoculum. Here, we locally administered low and high inoculum of lymphocytic choriomeningitis virus (LCMV) in mice to follow activation parameters of Ag-specific CD4
and CD8
T cells in draining lymph nodes (LNs) during the first 72 h post infection. We correlated these data with kinapse- and synapse-like motility patterns of Ag-specific T cells obtained by intravital imaging of draining LNs. Our data show that initial viral inoculum controls immediate synapse-like T cell arrest vs. continuous kinapse-like motility. This remains the case when the viral inoculum and thus the inflammatory microenvironment in draining LNs remains identical but cognate pMHC levels vary. Our data imply that the Ag-processing capacity of draining LNs is equipped to rapidly present high levels of cognate pMHC when antigenic material is abundant. Our findings further suggest that widespread T cell arrest during the first 72 h of an antimicrobial immune responses is not required to trigger proliferation. In sum, T cells adapt their scanning behavior according to available antigen levels during viral infections, with dynamic changes in motility occurring before detectable expression of early activation markers.
ObjectiveThe aim of this study was to identify factors associated with mortality in children under 5 years of age using a nationally representative sample of singleton births for the period of ...2004–2011.Design, setting and participantsPooled 2004, 2007 and 2011 cross-sectional data sets of the Bangladesh Demographic and Health Surveys were analysed. The surveys used a stratified two-stage cluster sample of 16 722 singleton live-born infants of the most recent birth of a mother within a 3-year period.Main outcome measuresOutcome measures were neonatal mortality (0–30 days), postneonatal mortality (1–11 months), infant mortality (0–11 months), child mortality (1–4 years) and under-5 mortality (0–4 years).ResultsSurvival information for 16 722 singleton live-born infants and 522 deaths of children <5 years of age included: 310 neonatal deaths, 154 postneonatal deaths, 464 infant deaths, 58 child deaths and 522 under-5 deaths. Multiple variable analysis showed that, over a 7-year period, mortality reduced significantly by 48% for postneonatal deaths, 33% for infant deaths and 29% for under-5 deaths, but there was no significant reduction in neonatal deaths (adjusted OR (AOR)=0.79, 95% CI 0.59 to 1.06) or child deaths (AOR=1.00, 95% CI 0.51 to 1.94). The odds of neonatal, postneonatal, infant, child and under-5 deaths decreased significantly among mothers who used contraceptive and mothers who had other children aged 3 years or older. The risk of neonatal, postneonatal, infant, child and under-5 deaths was significantly higher in mothers who reported a previous death of a sibling.ConclusionsOur study suggests that family planning is needed to further reduce the overall rate of under-5 deaths in Bangladesh. To reduce childhood mortality, public health interventions that focus on child spacing and contraceptive use by mothers may be most effective.
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