Structure of the Human cGAS–DNA Complex Reveals Enhanced Control of Immune Surveillance
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There is ample evidence to suggest that space flight leads to immune system dysregulation. This may be a result of microgravity, confinement, physiological stress, radiation, environment or other mission-associated factors. The clinical risk (if any) from prolonged immune dysregulation during exploration-class space flight has not yet been determined, but may include increased incidence of infection, allergy, hypersensitivity, hematological malignancy or altered wound healing. Each of the clinical events resulting from immune dysfunction has the potential to impact mission critical objectives during exploration-class missions. To date, precious little in-flight immune data has been generated to assess this phenomenon. The majority of recent flight immune studies have been post-flight assessments, which may not accurately reflect the in-flight status of immunity as it resolves over prolonged flight. There are no procedures currently in place to monitor immune function or its effect on crew health. The objective of this Supplemental Medical Objective (SMO) is to develop and validate an immune monitoring strategy consistent with operational flight requirements and constraints. This SMO will assess immunity, latent viral reactivation and physiological stress during both short and long duration flights. Upon completion, it is expected that any clinical risks resulting from the adverse effects of space flight on the human immune system will have been determined. In addition, a flight-compatible immune monitoring strategy will have been developed with which countermeasures validation could be performed. This study will determine, to the best level allowed by current technology, the in-flight status of crewmembers' immune systems. The in-flight samples will allow a distinction between legitimate in-flight alterations and the physiological stresses of landing and readaptation which are believed to alter R+0 assessments. The overall status of the immune system during flight (activation, deficiency, dysregulation) and the response of the immune system to specific latent virus reactivation (known to occur during space flight) will be thoroughly assessed. The first in-flight activity for integrated immunity very recently occurred during the STS-120 Space Shuttle mission. The protocols functioned well from a technical perspective, and accurate in-flight data was obtained from 1 Shuttle and 2 ISS crewmembers. Crew participation rates for the study continue to be robust.
Determining the effect of space travel on the human immune system has proven to be extremely challenging. Limited opportunities for in-flight studies, varying mission durations, technical and logistical obstacles, small subject numbers, and a broad range of potential assays have contributed to this problem. Additionally, the inherent complexity of the immune system, with its vast array of cell populations, sub-populations, diverse regulatory molecules, and broad interactions with other physiological systems, makes determining precise variables to measure very difficult. There is also the challenge of determining the clinical significance of any observed immune alterations. Will such a change lead to disease, or is it a transient subclinical observation related to short-term stress? The effect of this problem may be observed by scanning publications associated with immunity and spaceflight, which began to appear during the 1970s. Although individually they are each valid studies, the comprehensive literature to date suffers from widely varying sampling methods and assay techniques, low subject counts, and sometimes a disparate focus on narrow aspects of immunity. The most clinically relevant data are derived from in-flight human studies, which have demonstrated altered cell-mediated immunity and reactivation of latent herpes viruses. Much more data are available from post-flight testing of humans, with clear evidence of altered cytokine production patterns, altered leukocyte distribution, continued latent viral reactivation, and evidence of dramatically altered virus-specific immunity. It is unknown if post-flight assessments relate to the in-flight condition or are a response to landing stress and readaptation. In-flight culture of cells has clearly demonstrated that immune cells are gravity-sensitive and display altered functional characteristics. It is unknown if these data are related to in vivo immune cell function or are an artifact of microgravity culture. Ground analog testing of humans and animals, as well as microgravity-analog cell culture, has demonstrated utility. However, in all cases, it is not known with certainty if these data would reflect similar testing during space travel. Given their ready availability, ground analogs may be extremely useful for assay development and the evaluation of potential countermeasures. In general, the evidence base suffers from widely disparate studies on small numbers of subjects that do not directly correlate well with each other or spaceflight itself. Also lacking are investigations of the effect of gender on adaption to spaceflight. This results in significant knowledge 'gaps' that must be filled by future studies to completely determine any clinical risk related to immunity for human exploration-class space missions. These gaps include a significant lack of in-flight data, particularly during long-duration space missions. The International Space Station represents an excellent science platform with which to address this knowledge gap. Other knowledge gaps include lack of a single validated ground analog for the phenomenon and a lack of flight-compatible laboratory equipment capable of monitoring astronauts (for either clinical or research purposes). However, enough significant data exist, as described in this manuscript, to warrant addressing this phenomenon during the utilization phase of the ISS. A recent Space Shuttle investigation has confirmed the 31 in-flight nature of immune dysregulation, demonstrating that it is not merely a post-flight phenomenon. Several current studies are ongoing onboard the ISS that should thoroughly characterize the phenomenon. NASA recognizes that if spaceflight-associated immune dysregulation persists during exploration flights in conjunction with other dangers, such as high-energy radiation, the result may be a significant clinical risk. This emphasizes the need for a continued integrated comprehensive approach to determining the effect of prolonged spaceflight, separated from transient launch and landing stresses, on human immunity. After such studies, the phenomenon will be understood, and, hopefully, a monitoring strategy will have been developed that could be used to monitor the effectiveness of countermeasure
The changes in immune function which occur during space flight potentially expose the crews to an increased risk for development of illness. Decreased cellular immune function has been repeatedly documented after space flight and confirmed during flight by in vivo delayed-type hypersensitivity testing. However, correlation of immune changes with a clinically significant risk factor has not yet been performed. Our hypothesis is that space flight induces a decrease in cell-mediated immune function accompanied by a shift from a type 1 cytokine pattern (favoring cell-mediated immunity) to a type 2 cytokine pattern (favoring humoral immunity). We further hypothesize that reactivation of latent viruses will occur during space flight in association with the decreased cellular immunity. To test these hypotheses, we will determine the effects of space flight on cell-mediated immunity and viral reactivation. We will utilize delayed-type hypersensitivity testing as an in vivo measure of integrated cell-mediated immune function. The production of cytokines and immunoregulatory factors by lymphocytes and monocytes will be measured to determine whether changes in cytokine patterns are associated with the space flight-induced immune dysregulation. Correlation of antigen-specific immune changes with reactivation of latent herpes viruses will be determined by measuring peripheral levels of viral (CMV, VZV, EBV) antigen-specific T cells and comparing to the levels of EBV-infected B-cells by fluorescence in situ hybridization and flow cytometry. A comparison of cell-mediated immune function, cytokine regulation and viral reactivation will provide new insights into crew member health risks during flight.
Alterations and impairment of immune responses in humans present a health risk for space exploration missions. The molecular mechanisms under pinning innate immune defense can be confounded by the complexity of the acquired immune system of humans. Drosophila (fruit fly) innate immunity is simpler, and shares many similarities with human innate immunity at the level of molecular and genetic pathways. The goals of this study were to elucidate fundamental immune processes in Drosophila affected by spaceflight and to measure host-pathogen responses post-flight. Five containers, each containing ten female and five male fruit flies, were housed and bred on the space shuttle (average orbit altitude of330.35 km) for 12 days and 18.5 hours. A new generation of flies was reared in microgravity. In larvae, the immune system was examined by analyzing plasmatocyte number and activity in culture. In adults, the induced immune responses were analyzed by bacterial clearance and quantitative real-time polymerase chain reaction (qPCR) of selected genes following infection with E. coli. The RNA levels of relevant immune pathway genes were determined in both larvae and adults by microarray analysis. The ability of larval plasmatocytes to phagocytose E. coli in culture was attenuated following spaceflight, and in parallel, the expression of genes involved in cell maturation was down regulated. In addition, the level of constitutive expression of pattern recognition receptors and opsonins that specifically recognize bacteria, and of lysozymes, antimicrobial peptide (AMP) pathway and immune stress genes, hallmarks of humoral immunity, were also reduced in larvae. In adults, the efficiency of bacterial clearance measured in vivo following a systemic infection with E. coli post-flight, remained robust. We show that spaceflight altered both cellular and humoral immune responses in Drosophila and that the disruption occurs at multiple interacting pathways.
Pattern-triggered immunity and effector-triggered immunity are two primary forms of innate immunity in land plants. The molecular components and connecting nodes of pattern-triggered immunity and effector-triggered immunity are not fully understood. Here, we report that the Arabidopsis calcium-dependent protein kinase CPK3 is a key regulator of both pattern-triggered immunity and effector-triggered immunity. In vitro and in vivo phosphorylation assays, coupled with genetic and cell biology-based analyses, show that actin-depolymerization factor 4 (ADF4) is a physiological substrate of CPK3, and that phosphorylation of ADF4 by CPK3 governs actin cytoskeletal organization associated with pattern-triggered immunity. CPK3 regulates stomatal closure induced by flg22 and is required for resistance to Pst DC3000. Our data further demonstrates that CPK3 is required for resistance to Pst DC3000 carrying the effector AvrPphB. These results suggest that CPK3 is a missing link between cytoskeleton organization, pattern-triggered immunity and effector-triggered immunity.
Highlights: • Uterine flush (UF) from Day-7 pregnant cows modulates local uterine immunity. • Interferon-tau (IFNT) from Day-7 embryos in the UF mediates this immune modulation. • In vitro stimulation of IFNT induces similar immune regulation in immune cells. • IFNT regulated immune modulation may pave the way for embryo acceptance on Day-7. Recent studies suggest that Day-7 bovine embryo starts to communicate with the uterine epithelium through interferon-tau (IFNT) signaling. However, immune modulatory role of IFNT in the uterus just after the embryo moves from the oviduct is unclear. We aimed to examine the hypothesis that Day-7 bovine embryo secretes IFNT in the uterus, which induces anti-inflammatory response in immune cells. The uterine flush (UF) with multiple embryos was collected from Day-7 donor pregnant cows and peripheral blood mononuclear cells (PBMCs) were then cultured in UF. Transcripts detected in PBMCs revealed that UF from pregnant cows down-regulated pro-inflammatory cytokines (TNFA, IL1B) and up-regulated anti-inflammatory cytokine (IL10) expression, with activation of interferon-stimulated genes (ISGs; ISG15, OAS1) as compared with UF from non-pregnant cows. An addition of specific anti-IFNT antibody to the UF inhibited the effect on PBMCs, indicating that IFNT is a major factor for such immune modulation. The observation that conditioned media from bovine uterine epithelial cells both stimulated with IFNT in vitro and supplemented with fresh IFNT induced similar PBMCs gene expression, confirming that IFNT directly acts on this immune crosstalk. This study shows that IFNT secreted from Day-7 embryo in vivo generates anti-inflammatory response in immune cells, which may provide immunological tolerance to accept the embryo.
The organisms that make us ill, such as bacteria, viruses, and fungi, are like attacking armies. We now know a great deal more about this unseen world of microscopic invaders. Fortunately for us, the human immune system is ever vigilant against them. Microorganisms such as bacteria, viruses, and fungi occupy almost every corner of the Earth, and even parts of the human body. Some organisms are beneficial to us, helping to produce milk, cheese or yogurt. Others are potentially harmful, yet we don#t always develop illnesses from them; they are kept in check by the sentinels of our immune system. Our immune system is routinely challenged by these organisms every day. When the immune response is diminished, our ability to fight off these "bugs" is lowered. And that's when we become ill. Space flight presents a challenge to the immune system. Scientists believe that the stressful conditions of space flight - launch into orbit, adapting to microgravity, heavy workloads, and isolation from family and friends, to name but a few - reduce the astronauts' immunity. This immune suppression makes them more susceptible to common illnesses from bacteria and to re-infections from latent viruses in the body. In addition, risk of spreading illness in the confined environment of the Space Shuttle is high. Understanding changes in immune function will help scientists develop ways to keep astronauts healthy in space. This knowledge can also benefit earthbound populations. This experiment will give scientists insight into the immune system by comparing how certain cells of astronauts' innate immune system - the first line of defense against invaders - function after flight compared to before flight.
Background: Concordia Station is located inside Antarctica about 1000km from the coast at an altitude of 3200m (Dome C). Hence, individuals living in this harsh environment are exposed to two major conditions: 1.) hypobaric hypoxia and 2.) confinement and extreme isolation. Both hypoxia and confinement can affect human immunity and health, and are likely to be present during exploration class space missions. This study focused on immune alterations measured by a new global immunity test assay, similar to the phased out delayed type hypersensitivity (DTH) skin test. Methods: After informed written consent 14 healthy male subjects were included to the CHOICE-study (Consequences-of-longterm-Confinement-and-Hypobaric-HypOxia-on-Immunity-in-the Antarctic-Concordia-Environment). Data collection occurred during two winter-over periods lasting each one year. During the first campaign 6 healthy male were enrolled followed by a second campaign with 8 healthy males. Blood was drawn monthly and incubated for 48h with various bacterial, viral and fungal antigens followed by an analysis of plasma cytokine levels (TNF-alpha, IL2, IFN-gamma, IL10). As a control, blood was incubated without stimulation ("resting condition"). Goals: The scope of this study was to assess the consequences of hypoxia and confinement on cellular immunity as assessed by a new in vitro DTH-like test. Results: Initial results indicate that under resting conditions the in vitro DTH-like test showed low cytokine levels which remained almost unchanged during the entire observation period. However, cytokine responses to viral, bacterial and fungal antigens were remarkably reduced at the first month after arrival at Concordia when compared to levels measured in Europe prior to departure for Antarctica. With incrementing months of confinement this depressed DTH-like response tended to reverse, and in fact to show an "overshooting" immune reaction after stimulation. Conclusion: The reduced in vitro DTH-like test response in the early phase of Antarctic wintering over con rms distinct immune suppressive effects seen after (sub-)acute hypobaric hypoxia. The reversal and overshooting reaction of cellular immune responses upon stimulation, but not the resting state, indicate either a) priming of immune answers and/or b) an uncoupled or disregulated control of cellular immune answers by auto-, para- and endocrine pathways. Further analyses and correlations are warranted. Acknowledgement: Supported by the European Space Agency (ESA), the French (IPEV) and Italian (PNRA) polar institutes, the German National Space Program (DLR, 50WB0719/WB0919), by BELSPO/PROEDEX/ESA (C90-380/-391), NASA and by the Concordia crews who have participated with great enthusiasm.
The impact of spaceflight on immune function is undoubtedly a critical focus in the area of space biology and human health research. Heat shock proteins (Hsp) are an evolutionarily conserved family of proteins that are expressed in response to cellular and physiological stressors, experienced during radiation exposure, confinement, circadian rhythm disruption, and altered gravity (hypergravity experienced at launch/landing and microgravity experienced in-flight). In particular, Hsp70 aids in the folding of proteins, facilitates the movement of proteins across the membranes during signal transductions and can stimulate innate immunity. Since Hsp70 is induced during cellular stress, and can act as a stimulator for innate immunity, we sought to address how a loss of Hsp70 affects immunity, under the stress-inducing model of acute and chronic hypergravity. Moreover, the effects of gravity as a continuum on the induction of Hsps and key immune genes were also assessed to determine if increased cellular stress, via increased gravity (g)-force, contributes to immune dysfunctions. For this, wildtype (W1118) and Hsp70 deficient (Hsp70null) Drosophila melanogaster were subjected to simulated hypergravity at increasing levels of g-force (1.2g, 3g, and 5g) for acute (1hr) and chronic (7-day) timepoints and were compared to 0g 'non-hypergravity' controls. Following simulation, whole bodies were sex-segregated, RNA was isolated and quantitative (q)PCR was performed to determine differential immune gene expression profiles. Further, functional output of hemocytes were assessed by a phagocytosis assay. Collectively, these studies evaluated the effects of Hsp70 in the context of immunity during acute and chronic hypergravity. Indeed, relevance for this work can directly translate to acute effects of launch/landing gravitational forces upon liftoff (~1.7g) and entry (~3.4g) that astronauts experience. In addition, the effects of chronic cellular stress is directly relevant to the immune health of astronauts on long duration missions, as well. Thus, as we approach the goal of returning to the Moon and landing the first humans on Mars, an evaluation of gravity as a continuum and the stress-inducing effects of altered gravity experienced during spaceflight on astronaut immunity and health are necessary.
Space flight has been shown to have profound effects on immunological parameters of humans, monkeys and rodents. These studies have been carried out by a number of different laboratories. Among the parameters affected are leukocyte blastogenesis, natural killer cell activity, leukocyte subset distribution, cytokine production - including interferons and interleukins, and macrophage maturation and activity. These changes start to occur only after a few days space flight, and some changes continue throughout long-term space flight. Antibody responses have received only very limited study, and total antibody levels have been shown to be increased after long-term space flight. Several factors could be involved in inducing these changes. These factors could include microgravity, lack of load-bearing, stress, acceleration forces, and radiation. The mechanism(s) for space flight-induced changes in immune responses remain(s) to be established. Certainly, there can be direct effects of microgravity, or other factors, on cells that play a fundamental role in immune responses. However, it is now clear that there are interactions between the immune system and other physiological systems that could play a major role. For example, changes occurring in calcium use in the musculoskeletal system induced by microgravity or lack of use could have great impact on the immune system. Most of the changes in immune responses have been observed using samples taken immediately after return from space flight. However, there have been two recent studies that have used in-flight testing. Delayed-type hypersensitivity responses to common recall antigens of astronauts and cosmonauts have been shown to be decreased when tested during space flights. Additionally, natural killer cell and blastogenic activities are inhibited in samples taken from rats during space flight. Therefore, it is now clear that events occurring during space flight itself can affect immune responses. The biological significance of space flight-induced changes in immune parameters remains to be established; however, as duration of flights increases, the potential for difficulties due to impaired immune responses also increases.
Spaceflight missions can cause immune system dysfunction in astronauts with little understanding of immune outcomes in deep space. This study assessed immune responses in mice following ground-based, simulated deep spaceflight conditions, compared to data from astronauts on ISS missions. For ground studies, we simulated microgravity using the hindlimb unloaded mouse model alone or in combination with acute simulated galactic cosmic rays or solar particle events irradiation. Immune profiling results revealed unique immune diversity following each experimental condition, suggesting each stressor results in distinct circulating immune responses, with clear consequences for deep spaceflight. Circulating plasma microRNA sequence analysis revealed involvement in immune system dysregulation. Furthermore, a large astronaut cohort showed elevated inflammation during LEO missions, thereby supporting our simulated ground experiments in mice. Herein, circulating immune biomarkers are defined by distinct deep space irradiation types coupled to simulated microgravity and could be targets for future space health initiatives.
Despite the successes of immunotherapy in cancer treatment over recent decades, less than <10%–20% cancer cases have demonstrated durable responses from immune checkpoint blockade. To enhance the efficacy of immunotherapies, combination therapies suppressing multiple immune evasion mechanisms are increasingly contemplated. To better understand immune cell surveillance and diverse immune evasion responses in tumor tissues, we comprehensively characterized the immune landscape of more than 1,000 tumors across ten different cancers using CPTAC pan-cancer proteogenomic data. We identified seven distinct immune subtypes based on integrative learning of cell type compositions and pathway activities. We then thoroughly categorized unique genomic, epigenetic, transcriptomic, and proteomic changes associated with each subtype. Further leveraging the deep phosphoproteomic data, we studied kinase activities in different immune subtypes, which revealed potential subtype-specific therapeutic targets. Insights from this work will facilitate the development of future immunotherapy strategies and enhance precision targeting with existing agents.
Abstract Introduction The immune system and hypoxia are major factors influencing radiosensitivity in patients with different cancer types. This study aimed at developing a model to predict radiotherapy response in patients with head and neck squamous cell carcinoma (HNSCC) based on the tumor immune microenvironment and hypoxia signature. Materials and Methods We first evaluated the hypoxia status and tumor immune microenvironment in the Cancer Genome Atlas (TCGA) cohort by using transcriptomic data. Differentially expressed genes (DEGs) were identified between the “high immunity and low hypoxia” and “low immunity and high hypoxia” groups and those DEGs significantly associated with disease‐specific survival in the univariate Cox regression analysis were selected as the prognostic DEGs. We selected the immune hypoxia–related genes (IHRGs) by intersecting prognostic DEGs with immune and hypoxia gene sets. We used the IHRGs to train a multivariate Cox regression model in the TCGA cohort, based on which we calculated the IHRG prognostic index (IHRGPI) for each patient and validated its efficacy in predicting radiotherapy response in the Gene Expression Omnibus cohorts. Furthermore, we explored potential mechanisms and effective combinational treatment strategies for different IHRGPI groups. Results Five IHRGs were used to construct the IHRGPI, which was used to dichotomize the cohorts. The patients with lower IHRGPI showed a better radiotherapy response across different cohorts and endpoints, including overall survival, progression‐free survival, and recurrence‐free survival ( p < 0.05). Patients with higher IHRGPI showed greater hypoxia and lesser immune cell infiltration. A lower IHRGPI indicated a better immunotherapy response, while a higher IHRGPI indicated a better chemotherapy response. Conclusions IHRGPI is promising for predicting radiotherapy response and guiding combinational treatment strategies in patients with HNSCC.