The danger model: a renewed sense of self

Transient autoantibodies to danger signals

The Danger Model predicts that there are some molecules that no immune system can ever be fully tolerant of, namely proteins that are only transiently expressed during times of stress, infection, or injury. Among these are the danger/alarm signals themselves. Accordingly, a fleeting autoantibody response to danger signals is expected during times when they are released. Depending on context, these autoantibodies may serve beneficial "housekeeping" functions by removing surplus danger signals from the circulation or, conversely, create an immunodeficiency. Here, we will focus on the Type 1 Interferons as examples of foreseeable targets for a transient autoantibody response, but the principles outlined should hold for other danger-associated molecules as well.

Interaction between nanomaterials and the innate immune system across evolution

Interaction of engineered nanomaterials (ENMs) with the immune system mainly occurs with cells and molecules of innate immunity, which are present in interface tissues of living organisms. Immuno-nanotoxicological studies aim at understanding if and when such interaction is inconsequential or may cause irreparable damage. Since innate immunity is the first line of immune reactivity towards exogenous agents and is highly conserved throughout evolution, this review focuses on the major effector cells of innate immunity, the phagocytes, and their major sensing receptors, Toll-like receptors (TLRs), for assessing the modes of successful versus pathological interaction between ENMs and host defences. By comparing the phagocyte- and TLR-dependent responses to ENMs in plants, molluscs, annelids, crustaceans, echinoderms and mammals, we aim to highlight common recognition and elimination mechanisms and the general sufficiency of innate immunity for maintaining tissue integrity and homeostasis.

Toll-like Receptor 4 in Acute Kidney Injury

Acute kidney injury (AKI) is a common and devastating pathologic condition, associated with considerable high morbidity and mortality. Although significant breakthroughs have been made in recent years, to this day no effective pharmacological therapies for its treatment exist. AKI is known to be connected with intrarenal and systemic inflammation. The innate immune system plays an important role as the first defense response mechanism to tissue injury. Toll-like receptor 4 (TLR4) is a well-characterized pattern recognition receptor, and increasing evidence has shown that TLR4 mediated inflammatory response, plays a pivotal role in the pathogenesis of acute kidney injury. Pathogen-associated molecular patterns (PAMPS), which are the conserved microbial motifs, are sensed by these receptors. Endogenous molecules generated during tissue injury, and labeled as damage-associated molecular pattern molecules (DAMPs), also activate pattern recognition receptors, thereby offering an understanding of sterile types of inflammation. Excessive, uncontrolled and/or sustained activation of TLR4, may lead to a chronic inflammatory state. In this review we describe the role of TLR4, its endogenous ligands and activation in the inflammatory response to ischemic/reperfusion-induced AKI and sepsis-associated AKI. The potential regeneration signaling patterns of TLR4 in acute kidney injury, are also discussed.

Anti-cancer Virotherapy in Russia: Lessons from the Past, Current Challenges and Prospects for the Future

The idea of using the lytic power of viruses against malignant cells has been entertained for many decades. However, oncolytic viruses gained broad attention as an emerging anti-cancer therapy only recently with the successful implementation of several oncolytic viruses to treat advanced melanoma. Here we review the history of oncolytic viruses in the Russian Federation and recent biotechnological advances in connection with the perspectives of their practical use against aggressive tumors such as glioblastoma or pancreatic cancer. A particular emphasis is made on novel applications of safe non-lytic virus-derived vectors armed with prodrug-converting enzyme transgenes. Rational improvement of oncotropism by conjugation with biopolymers and nanoformulations is also discussed.

Molecular Chaperone Receptors: An Update

Extracellular heat shock proteins (HSP) play important roles in cell signaling and immunity. Many of these effects are mediated by surface receptors expressed on a wide range of cell types, including immune cells. We have investigated the nature of such proteins by cloning candidate receptors into cells (CHO-K1) with the rare property of being null for HSP binding. Using this approach, we have discovered that mammalian and eukaryotic Hsp70 binds avidly to at least three classes of receptor including: (1) c-type lectin receptors (CLR), (2) scavenger receptors (SR) and (3) lectins. However, the structural nature of the receptor-ligand interactions is not currently clear. Hsp70 can bind to LOX-1 (a member of both the CLR and SR), with the c-type lectin binding domain (CTLD), to the SR family members SREC-I and FEEL-1/CLEVER-1/STABILIN-1, which by contrast have arrays of EGF-like repeats in their extracellular domains as well. In this chapter, we will discuss: (1) methods for the discovery of HSP receptors, (2) approaches to the study of individual receptors in cells that contain multiple such receptors and (3) methods for investigating HSP receptor function in vivo.

The diverse roles of C-type lectin-like receptors in immunity

Our understanding of the C-type lectin-like receptors (CTLRs) and their functions in immunity have continued to expand from their initial roles in pathogen recognition. There are now clear examples of CTLRs acting as scavenger receptors, sensors of cell death and cell transformation, and regulators of immune responses and homeostasis. This range of function reflects an extensive diversity in the expression and signaling activity between individual CTLR members of otherwise highly conserved families. Adding to this diversity is the constant discovery of new receptor binding capabilities and receptor-ligand interactions, distinct cellular expression profiles, and receptor structures and signaling mechanisms which have expanded the defining roles of CTLRs in immunity. The natural killer cell receptors exemplify this functional diversity with growing evidence of their activity in other immune populations and tissues. Here, we broadly review select families of CTLRs encoded in the natural killer cell gene complex (NKC) highlighting key receptors that demonstrate the complex multifunctional capabilities of these proteins. We focus on recent evidence from research on the NKRP1 family of CTLRs and their interaction with the related C-type lectin (CLEC) ligands which together exhibit essential immune functions beyond their defined activity in natural killer (NK) cells. The ever-expanding evidence for the requirement of CTLR in numerous biological processes emphasizes the need to better understand the functional potential of these receptor families in immune defense and pathological conditions.

Induction of T-helper-17-cell-mediated anti-tumour immunity by pathogen-mimicking polymer nanoparticles

The effectivity of cancer immunotherapies is hindered by immunosuppressive tumour microenvironments that are poorly infiltrated by effector T cells and natural killer cells. In infection and autoimmune disease, the recruitment and activation of effector immune cells is coordinated by pro-inflammatory T helper 17 (TH17) cells. Here we show that pathogen-mimicking hollow nanoparticles displaying mannan (a polysaccharide that activates TH17 cells in microbial cell walls) limit the fraction of regulatory T cells and induce TH17-cell-mediated anti-tumour responses. The nanoparticles activate the pattern-recognition receptor Dectin-2 and Toll-like receptor 4 in dendritic cells, and promote the differentiation of CD4+ T cells into the TH17 phenotype. In mice, intra-tumoural administration of the nanoparticles decreased the fraction of regulatory T cells in the tumour while markedly increasing the fractions of TH17 cells (and the levels of TH17-cell-associated cytokines), CD8+ T cells, natural killer cells and M1-like macrophages. The anti-tumoural activity of the effector cells was amplified by an agonistic antibody against the co-stimulatory receptor OX40 in multiple mouse models. Nanomaterials that induce TH17-cell-mediated immune responses may have therapeutic potential.

Chemotherapy to potentiate the radiation-induced immune response

Chemoradiation (CRT) is a conventional therapy used in local cancers, especially when they are locally advanced. Studies have shown that CRT induces strong anti-tumor responses involving several immune effects in pre-clinical models and humans. In this review, we have described the various immune effects involved in CRT efficacy. Indeed, effects such as immunological cell death, activation and maturation of antigen-presenting cells, and activation of an adaptive anti-tumor immune response are attributed to CRT. As often described in other therapies, various immunosuppressive mechanisms mediated, in particular, by Treg and myeloid populations may reduce the CRT efficacy. We have therefore discussed the relevance of combining CRT with other therapies to potentiate the CRT-induced anti-tumor effects.

Mitochondrial reactivity following acute exposure to experimental pain testing in people with HIV and chronic pain

Background: Physical stressors can cause a physiological response that can contribute to an increase in mitochondrial dysfunction and Mitochondrial DNA damage (mtDNA damage). People living with HIV (PWH) are more likely to suffer from chronic pain and may be more susceptible to mitochondrial dysfunction following exposure to a stressor. We used Quantitative Sensory Testing (QST) as an acute painful stressor in order to investigate whether PWH with/without chronic pain show differential mitochondrial physiological responses. Methods: The current study included PWH with (n = 26), and without (n = 29), chronic pain. Participants completed a single session that lasted approximately 180 min, including QST. Blood was taken prior to and following the QST battery for assays measuring mtDNA damage, mtDNA copy number, and mtDNA damage-associated molecular pattern (DAMP) levels (i.e., ND1 and ND6). Results: We examined differences between those with and without pain on various indicators of mitochondrial reactivity following exposure to QST. However, only ND6 and mtDNA damage were shown to be statistically significant between pain groups. Conclusion: PWH with chronic pain showed greater mitochondrial reactivity to laboratory stressors. Consequently, PWH and chronic pain may be more susceptible to conditions in which mitochondrial damage/dysfunction play a central role, such as cognitive decline.

Regulatory T cells (Tregs) and their therapeutic potential against autoimmune disorders - Advances and challenges

Autoimmune diseases are caused when immune cells act against self-protein. This biological self-non-self-discrimination phenomenon is controlled by a distinct group of lymphocytes known as regulatory T cells (Tregs), which are key inflammatory response regulators and play a pivotal role in immune tolerance and homeostasis. Treg-mediated robust immunosuppression provides self-tolerance and protection against autoimmune diseases. However, once this system fails to operate or poorly operate, it leads to an extreme situation where immune system reacts against self-antigens and destroys host organs, thus causing autoimmune diseases. Tregs can target both innate and adaptive immunity via modulating multiple immune cells such as neutrophils, monocytes, antigen-presenting cells, B cells, and T cells. This review highlights the Treg-mediated immunosuppression, role of several markers and their interplay during Treg development and differentiation, and advances in therapeutic aspects of Treg cells to reduce severity of autoimmunity-related conditions along with emphasizing limitations and challenges of their usages.

Adaptive discrimination between harmful and harmless antigens in the immune system by predictive coding

The immune system discriminates between harmful and harmless antigens based on past experiences; however, the underlying mechanism is largely unknown. From the viewpoint of machine learning, the learning system predicts the observation and updates the prediction based on prediction error, a process known as "predictive coding." Here, we modeled the population dynamics of T cells by adopting the concept of predictive coding; conventional and regulatory T cells predict the antigen concentration and excessive immune response, respectively. Their prediction error signals, possibly via cytokines, induce their differentiation to memory T cells. Through numerical simulations, we found that the immune system identifies antigen risks depending on the concentration and input rapidness of the antigen. Further, our model reproduced history-dependent discrimination, as in allergy onset and subsequent therapy. Taken together, this study provided a novel framework to improve our understanding of how the immune system adaptively learns the risks of diverse antigens.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Resolution of acute cervical insufficiency after antibiotics in a case with amniotic fluid sludge

Cervical insufficiency generally refers to a condition in which there is mid-trimester cervical dilatation or protruding chorioamniotic membranes in the absence of uterine contractions. Such condition is a risk factor for spontaneous mid-trimester abortion or early preterm birth, and is associated with adverse neonatal outcomes. Both intra-amniotic infection and inflammation ascertained by amniocentesis have been identified in patients with cervical insufficiency, and are poor prognostic factors. A subset of patients with intra-amniotic inflammation will have no demonstrable microorganisms detected via cultivation or molecular methods, and therefore represent cases of sterile intra-amniotic inflammation. Amniotic fluid sludge (free-floating hyperechogenic material within the amniotic fluid in close proximity to the uterine cervix) identified on sonography is a biomarker for intra-amniotic infection and inflammation. Recent evidence suggests that intra-amniotic infection, as well as sterile intra-amniotic inflammation can be treated successfully using antimicrobial agents. We report a unique case in which administration of antibiotics in the presence of mid-trimester cervical insufficiency, sterile intra-amniotic inflammation, and amniotic fluid sludge was associated with resolution of the cervical findings, as demonstrated on both sonographic and speculum examination. The patient successfully underwent elective cesarean delivery at 36-2/7 weeks of gestation. This case illustrates that antibiotic therapy may be effective despite the presence of several high-risk pregnancy conditions, and that successful outcome is possible.

Pathology of drug hypersensitivity reactions and mechanisms of immune tolerance

Immune-mediated type IV adverse drug reactions are idiosyncratic in nature, generally not related to the primary or secondary pharmacology of the drug. Due to their complex nature and rarity, these iatrogenic reactions are seldom predicted or encountered during preclinical/early clinical development stages, and often precipitate upon exposure to wider populations (i.e. phase III onwards). They confer a burden on the healthcare sector in both a clinical and financial sense presenting a severe impediment to the drug discovery and development process. Research over the past 50 years has improved our understanding of these reactions markedly as both in vitro and in vivo studies have placed the role of the immune system, in particular; drug-responsive T cells, firmly in the spotlight as the mediators of these reactions. Indeed, the role of different populations of T cells in adverse events and the interaction of drug molecules with HLA proteins expressed on the surface of antigen-presenting cells is of considerable interest. Herein, this review examines the pathways of immune-mediated adverse events including the various T cell subtypes implicated and the mechanisms of T cell activation. Additionally, we address the enigma of immunological tolerance and explore the role tolerance plays in determination of susceptibility to such adverse events even in individuals carrying immunogenic liabilities.

Common immunopathogenesis of central nervous system diseases: the protein-homeostasis-system hypothesis

There are hundreds of central nervous system (CNS) diseases, but there are few diseases for which the etiology or pathogenesis is understood as well as those of other organ-specific diseases. Cells in the CNS are selectively protected from external and internal insults by the blood–brain barrier. Thus, the neuroimmune system, including microglia and immune proteins, might control external or internal insults that the adaptive immune system cannot control or mitigate. The pathologic findings differ by disease and show a state of inflammation that reflects the relationship between etiological or inflammation-inducing substances and corresponding immune reactions. Current immunological concepts about infectious diseases and infection-associated immune-mediated diseases, including those in the CNS, can only partly explain the pathophysiology of disease because they are based on the idea that host cell injury is caused by pathogens. Because every disease involves etiological or triggering substances for disease-onset, the protein-homeostasis-system (PHS) hypothesis proposes that the immune systems in the host control those substances according to the size and biochemical properties of the substances. In this article, I propose a common immunopathogenesis of CNS diseases, including prion diseases, Alzheimer’s disease, and genetic diseases, through the PHS hypothesis.

Nanoparticles for Chemoimmunotherapy Against Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) exhibits high recurrence and mortality rates because of the lack of effective treatment targets. Surgery and traditional chemotherapy are the primary treatment options. Immunotherapy shows high potential for treating various cancers but exhibits limited efficacy against TNBC as a monotherapy. Chemoimmunotherapy has broad prospects for applications for cancer treatment conferred through the synergistic immunomodulatory and anti-tumor effects of chemotherapy and immunotherapeutic strategies. However, improving the efficacy of synergistic therapy and reducing the side effects of multiple drugs remain to be the main challenges in chemoimmunotherapy against TNBC. Nanocarriers can target both cancer and immune cells, promote drug accumulation, and show minimal toxicity, making them ideal delivery systems for chemotherapeutic and immunotherapeutic agents. In this review, we introduce the immunomodulatory effects of chemotherapy and combined mechanisms of chemoimmunotherapy, followed by a summary of nanoparticle-mediated chemoimmunotherapeutic strategies used for treating TNBC. This up-to-date synthesis of relevant findings in the field merits contemplation, while considering avenues of investigation to enable advances in the field.

Analyzing some concepts of immune regulation of the last three decades: Fostering greater research resilience despite the information overload. A personal view

There is considerable interest in whether increased investment in science, made by society, pays dividends. Some plausibly argue the increased rate of production of information results in an ossification of the canon. Reports, challenging the canon, fall by the wayside. The field thus becomes increasingly complex, reflecting not so much the reality of nature but how we investigate the subject. I suggest that focusing on and resolving the paradoxes evident within a canon will free the logjam, resulting in more resilient research. Immunology is among the fastest growing of biological sciences and is, I suggest, an appropriate case study. I examine the commonly accepted frameworks employed over the last three decades to address two major, related immunological questions: what determines whether antigen activates or inactivates CD4 T cells, and so whether immune responses are initiated or this potential ablated; secondly, what determines the Th subset to which the activated Th cells belong, thus determining the class of immunity generated. I show there are major paradoxes within these frameworks, neglected for decades. I propose how research focused on resolving paradoxes can be better fostered, and so support the evolution of the canon. This perspective is pertinent in facing critical issues on how immune responses are regulated, and to more general issues of both the philosophy of science and of science policy.The last section is in response to questions and comments of the reviewers. It brings together several considerations to express my view: the same frameworks, formulated in response to the two questions, are useful in understanding the regulation of the immune response against model antigens, against self and foreign antigens, those of tumors and of pathogens.

Newborn screening for Pompe disease in Italy: Long-term results and future challenges

Pompe disease (PD) is a progressive neuromuscular disorder caused by a lysosomal acid α-glucosidase (GAA) deficiency. Enzymatic replacement therapy is available, but early diagnosis by newborn screening (NBS) is essential for early treatment and better outcomes, especially with more severe forms. We present results from 7 years of NBS for PD and the management of infantile-onset (IOPD) and late-onset (LOPD) patients, during which we sought candidate predictive parameters of phenotype severity at baseline and during follow-up. We used a tandem mass spectrometry assay for α-glucosidase activity to screen 206,741 newborns and identified 39 positive neonates (0.019%). Eleven had two pathogenic variants of the GAA gene (3 IOPD, 8 LOPD); six carried variants of uncertain significance (VUS). IOPD patients were treated promptly and had good outcomes. LOPD and infants with VUS were followed; all were asymptomatic at the last visit (mean age 3.4 years, range 0.5–5.5). Urinary glucose tetrasaccharide was a useful and biomarker for rapidly differentiating IOPD from LOPD and monitoring response to therapy during follow-up. Our study, the largest reported to date in Europe, presents data from longstanding NBS for PD, revealing an incidence in North East Italy of 1/18,795 (IOPD 1/68,914; LOPD 1/25,843), and the absence of mortality in IOPD treated from birth. In LOPD, rigorous long-term follow-up is needed to evaluate the best time to start therapy. The high pseudodeficiency frequency, ethical issues with early LOPD diagnosis, and difficulty predicting phenotypes based on biochemical parameters and genotypes, especially in LOPD, need further study.

Evolutionary Origins of Metabolic Reprogramming in Cancer

Metabolic changes that facilitate tumor growth are one of the hallmarks of cancer. These changes are not specific to tumors but also take place during the physiological growth of tissues. Indeed, the cellular and tissue mechanisms present in the tumor have their physiological counterpart in the repair of tissue lesions and wound healing. These molecular mechanisms have been acquired during metazoan evolution, first to eliminate the infection of the tissue injury, then to enter an effective regenerative phase. Cancer itself could be considered a phenomenon of antagonistic pleiotropy of the genes involved in effective tissue repair. Cancer and tissue repair are complex traits that share many intermediate phenotypes at the molecular, cellular, and tissue levels, and all of these are integrated within a Systems Biology structure. Complex traits are influenced by a multitude of common genes, each with a weak effect. This polygenic component of complex traits is mainly unknown and so makes up part of the missing heritability. Here, we try to integrate these different perspectives from the point of view of the metabolic changes observed in cancer.

Immunogenic cell death as driver of autoimmunity in granulomatosis with polyangiitis

Cell death and dysregulated clearance of dead cells play essential roles in the induction of chronic inflammatory processes and autoimmune diseases. Granulomatosis with polyangiitis (GPA), a neutrophil-driven autoimmune disorder, is characterized by necrotizing inflammation predominantly of the respiratory tract and an anti-neutrophil cytoplasmic autoantibody (ANCA)-associated systemic necrotizing vasculitis. Defective regulation of neutrophil homeostasis and cell death mechanisms have been demonstrated in GPA. Disturbed efferocytosis (i.e., phagocytosis of apoptotic neutrophils by macrophages) as well as cell death-related release of damage-associated molecular patterns (DAMP) such as high mobility group box 1 (HMGB1) contribute to chronic non-resolving inflammation in GPA. DAMP have been shown to induce innate as well as adaptive cellular responses thereby creating a prerequisite for the development of pathogenic autoimmunity. In this review, we discuss factors contributing to as well as the impact of regulated cell death (RCD) accompanied by DAMP-release as early drivers of the granulomatous tissue inflammation and autoimmune responses in GPA.

Deeper insight into the role of IL-17 in the relationship beween hypertension and intestinal physiology

With the incidence of hypertension increasing worldwide, more and more the mechanisms of hypertension from the perspective of immunity have found. Intestinal microbiota as well as its metabolites relationship with hypertension has attracted great attention from both clinicians and investigators. However, the associations of hypertension with lesions of a large number of immune factors including IL-17, MCP-1, IL-6, TGF-β, IL-10 and others have not been fully characterized. In this review, after introducing the immune factors as the most potent anti/pro-hypertension agents known, we provide detailed descriptions of the IL-17 involved in the pathology of hypertension, pointing out the underlying mechanisms and suggesting the clinical indications.

How cell migration helps immune sentinels

The immune system relies on the migratory capacity of its cellular components, which must be mobile in order to defend the host from invading micro-organisms or malignant cells. This applies in particular to immune sentinels from the myeloid lineage, i.e. macrophages and dendritic cells. Cell migration is already at work during mammalian early development, when myeloid cell precursors migrate from the yolk sac, an extra embryonic structure, to colonize tissues and form the pool of tissue-resident macrophages. Later, this is accompanied by a migration wave of precursors and monocytes from the bone marrow to secondary lymphoid organs and the peripheral tissues. They differentiate into DCs and monocyte-derived macrophages. During adult life, cell migration endows immune cells with the ability to patrol their environment as well as to circulate between peripheral tissues and lymphoid organs. Hence migration of immune cells is key to building an efficient defense system for an organism. In this review, we will describe how cell migratory capacity regulates the various stages in the life of myeloid cells from development to tissue patrolling, and migration to lymph nodes. We will focus on the role of the actin cytoskeletal machinery and its regulators, and how it contributes to the establishment and function of the immune system.

How the immune system shapes neurodegenerative diseases

Neurodegenerative diseases are a major cause of death and disability worldwide and are influenced by many factors including age, genetics, and injuries. While these diseases are often thought to result from the accumulation and spread of aberrant proteins, recent studies have demonstrated that they can be shaped by the innate and adaptive immune system. Resident myeloid cells typically mount a sustained response to the degenerating CNS, but peripheral leukocytes such as T and B cells can also alter disease trajectories. Here, we review the sometimes-dichotomous roles played by immune cells during neurodegenerative diseases and explore how brain trauma can serve as a disease initiator or accelerant. We also offer insights into how failure to properly resolve a CNS injury might promote the development of a neurodegenerative disease.

The circular RNA Edis regulates neurodevelopment and innate immunity

Circular RNAs (circRNAs) are widely expressed in eukaryotes. However, only a subset has been functionally characterized. We identify and validate a collection of circRNAs in Drosophila, and show that depletion of the brain-enriched circRNA Edis (circ_Ect4) causes hyperactivation of antibacterial innate immunity both in cultured cells and in vivo. Notably, Edis depleted flies display heightened resistance to bacterial infection and enhanced pathogen clearance. Conversely, ectopic Edis expression blocks innate immunity signaling. In addition, inactivation of Edis in vivo leads to impaired locomotor activity and shortened lifespan. Remarkably, these phenotypes can be recapitulated with neuron-specific depletion of Edis, accompanied by defective neurodevelopment. Furthermore, inactivation of Relish suppresses the innate immunity hyperactivation phenotype in the fly brain. Moreover, we provide evidence that Edis encodes a functional protein that associates with and compromises the processing and activation of the immune transcription factor Relish. Importantly, restoring Edis expression or ectopic expression of Edis-encoded protein suppresses both innate immunity and neurodevelopment phenotypes elicited by Edis depletion. Thus, our study establishes Edis as a key regulator of neurodevelopment and innate immunity.

Mathematical Models of Death Signaling Networks

This review provides an overview of the progress made by computational and systems biologists in characterizing different cell death regulatory mechanisms that constitute the cell death network. We define the cell death network as a comprehensive decision-making mechanism that controls multiple death execution molecular circuits. This network involves multiple feedback and feed-forward loops and crosstalk among different cell death-regulating pathways. While substantial progress has been made in characterizing individual cell death execution pathways, the cell death decision network is poorly defined and understood. Certainly, understanding the dynamic behavior of such complex regulatory mechanisms can be only achieved by applying mathematical modeling and system-oriented approaches. Here, we provide an overview of mathematical models that have been developed to characterize different cell death mechanisms and intend to identify future research directions in this field.

miR-486 improves fibrotic activity in myocardial infarction by targeting SRSF3/p21-Mediated cardiac myofibroblast senescence

The regulation of fibrotic activities is key to improving pathological remodelling post‐myocardial infarction (MI). Currently, in the clinic, safe and curative therapies for cardiac fibrosis and improvement of the pathological fibrotic environment, scar formation and pathological remodelling post‐MI are lacking. Previous studies have shown that miR‐486 is involved in the regulation of fibrosis. However, it is still unclear how miR‐486 functions in post‐MI regeneration. Here, we first demonstrated that miR‐486 targeting SRSF3/p21 mediates the senescence of cardiac myofibroblasts to improve their fibrotic activity, which benefits the regeneration of MI by limiting scar size and post‐MI remodelling. miR‐486‐targeted silencing has high potential as a novel target to improve fibrotic activity, cardiac fibrosis and pathological remodelling.

The future clinical implications of trained immunity

INTRODUCTION

Trained Immunity (TI) refers to the long-term modulation of the innate immune response, based on previous interactions with microbes, microbial ligands or endogenous substances. Through metabolic and epigenetic reprogramming, monocytes, macrophages and neutrophils develop an enhanced capacity to mount innate immune responses to subsequent stimuli and this is persistent due to alterations at the myeloid progenitor compartment.

AREAS COVERED

The purpose of this article is to review the current understanding of the TI process and discuss about its potential clinical implications in the near future. We address the evidence of TI involvement in various diseases, the currently developed new therapy, and discuss how TI may lead to new clinical tools to improve existing standards of care.

EXPERT OPINION

The state of art in this domain has made considerable progress, linking TI-related mechanisms in multiple immune-mediated pathologies, starting with infections to autoimmune disorders and cancers. As a relatively new area of immunology, it has seen fast progress with many of its applications ready to be investigated in clinical settings.

Destructive inflammatory reaction after an autologous retinal pigment epithelium and choroid transplantation: no detection of an auto-immune response

Purpose

Five patients who underwent uncomplicated retinal pigment epithelium (RPE)-choroid transplantation for neovascular age-related macular degeneration developed a destructive inflammatory reaction causing subretinal fluid accumulation and extensive RPE atrophy in the graft. We hypothesized that this inflammation could be caused by an auto-immune response against the graft, resulting in circulating auto-antibodies. The aim of our study was to examine a potential autoimmune origin, which would allow a more targeted therapy approach.

Methods

Five above-mentioned patients and four control groups of five patients each were included: 1) after uncomplicated RPE-choroid transplantation, 2) after full macular translocation, 3) treated with anti-vascular endothelial growth factor, and 4) healthy controls. Histopathology of rejected graft tissue was performed using standard procedures. Presence of RPE-choroid autoantibodies in serum was examined by indirect immunofluorescence and Western blot, and human leukocyte antigen (HLA) typing was performed.

Results

Histopathological examination of an explanted graft showed infiltration of T-lymphocytes and macrophages in the choroid and RPE, and an increased number of B-cell lymphocytes were found in the choroid. Indirect immunofluorescence showed weak RPE-choroid autoantibody immunoreactivity in three patients of different groups. Western blot did not show specific RPE-choroid autoantibody immunoreactivity and no difference of HLA genotypes between the groups was found.

Conclusions

Although local mononuclear inflammatory cell infiltration and a high number of B-lymphocytes were observed in an explanted graft, we did not detect serological evidence of an autoimmune origin of the postoperative inflammation using direct immunofluorescence and Western Blot. Alternatively, the graft failure may have been caused by local innate inflammation, triggered by breakdown of tolerance. Based on our current findings of this small study group, we have no rationale to pursue therapies targeted towards autoreactive graft failure. More research is needed to confirm our findings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12348-022-00305-2.

Molecular Mimicry between SARS-CoV-2 and Human Endocrinocytes: A Prerequisite of Post-COVID-19 Endocrine Autoimmunity?

Molecular mimicry between human and microbial/viral/parasite peptides is common and has long been associated with the etiology of autoimmune disorders provoked by exogenous pathogens. A growing body of evidence accumulated in recent years suggests a strong correlation between SARS-CoV-2 infection and autoimmunity. The article analyzes the immunogenic potential of the peptides shared between the SARS-CoV-2 spike glycoprotein (S-protein) and antigens of human endocrinocytes involved in most common autoimmune endocrinopathies. A total of 14 pentapeptides shared by the SARS-CoV-2 S-protein, thyroid, pituitary, adrenal cortex autoantigens and beta-cells of the islets of Langerhans were identified, all of them belong to the immunoreactive epitopes of SARS-CoV-2. The discussion of the findings relates the results to the clinical correlates of COVID-19-associated autoimmune endocrinopathies. The most common of these illnesses is an autoimmune thyroid disease, so the majority of shared pentapeptides belong to the marker autoantigens of this disease. The most important in pathogenesis of severe COVID-19, according to the authors, may be autoimmunity against adrenals because their adequate response prevents excessive systemic action of the inflammatory mediators causing cytokine storm and hemodynamic shock. A critique of the antigenic mimicry concept is given with an assertion that peptide sharing is not a guarantee but only a prerequisite for provoking autoimmunity based on the molecular mimicry. The latter event occurs in carriers of certain HLA haplotypes and when a shared peptide is only used in antigen processing

Bioengineering the Vascularized Endocrine Pancreas: A Fine-Tuned Interplay Between Vascularization, Extracellular-Matrix-Based Scaffold Architecture, and Insulin-Producing Cells

Intrahepatic islet transplantation is a promising β-cell replacement strategy for the treatment of type 1 diabetes. Instant blood-mediated inflammatory reactions, acute inflammatory storm, and graft revascularization delay limit islet engraftment in the peri-transplant phase, hampering the success rate of the procedure. Growing evidence has demonstrated that islet engraftment efficiency may take advantage of several bioengineering approaches aimed to recreate both vascular and endocrine compartments either ex vivo or in vivo. To this end, endocrine pancreas bioengineering is an emerging field in β-cell replacement, which might provide endocrine cells with all the building blocks (vascularization, ECM composition, or micro/macro-architecture) useful for their successful engraftment and function in vivo. Studies on reshaping either the endocrine cellular composition or the islet microenvironment have been largely performed, focusing on a single building block element, without, however, grasping that their synergistic effect is indispensable for correct endocrine function. Herein, the review focuses on the minimum building blocks that an ideal vascularized endocrine scaffold should have to resemble the endocrine niche architecture, composition, and function to foster functional connections between the vascular and endocrine compartments. Additionally, this review highlights the possibility of designing bioengineered scaffolds integrating alternative endocrine sources to overcome donor organ shortages and the possibility of combining novel immune-preserving strategies for long-term graft function.

Promises and Challenges of Immunogenic Chemotherapy in Multiple Myeloma

Immunological tolerance of myeloma cells represents a critical obstacle in achieving long-term disease-free survival for multiple myeloma (MM) patients. Over the past two decades, remarkable preclinical efforts to understand MM biology have led to the clinical approval of several targeted and immunotherapeutic agents. Among them, it is now clear that chemotherapy can also make cancer cells “visible” to the immune system and thus reactivate anti-tumor immunity. This knowledge represents an important resource in the treatment paradigm of MM, whereas immune dysfunction constitutes a clear obstacle to the cure of the disease. In this review, we highlight the importance of defining the immunological effects of chemotherapy in MM with the goal of enhancing the clinical management of patients. This area of investigation will open new avenues of research to identify novel immunogenic anti-MM agents and inform the optimal integration of chemotherapy with immunotherapy.

Molecular cloning and functional characterization of HMGB1 and HMGB2 in large yellow croaker Larimichthys crocea

High mobility group box 1 (HMGB1) and HMGB2 have been demonstrated to be key regulators not only in DNA recombination, replication, gene transcription, but also in host inflammation and immune responses. In the present study, orthologs of HMGB1 and HMGB2 named Lc-HMGB1 and Lc-HMGB2 were characterized in large yellow croaker (Larimichthys crocea). The ORFs of Lc-HMGB1 and Lc-HMGB2 are 621 bp and 648 bp, encoding proteins of 206 aa and 215 aa, with the putative Lc-HMGB1 and Lc-HMGB2 proteins both contain two HMG domains, respectively. The genome organizations of Lc-HMGB1 and Lc-HMGB2 are both composed of four exons and three introns, which are conserved in vertebrates. Lc-HMGB1 and Lc-HMGB2 were identified as cell nucleus localized proteins, and were ubiquitously distributed in the examined organs/tissues. Additionally, Lc-HMGB1 was significantly up-regulated under LPS and PGN stimulation, whereas the stimulation of poly I:C, LPS, PGN, and Pseudomonas plecoglossicida infection could significantly induce Lc-HMGB2 expression in vivo. Notably, both Lc-HMGB1 and Lc-HMGB2 overexpression could significantly up-regulated the expression of diverse immune-related genes, including IFN1, IRF3, ISG15, ISG56, RSAD2, g-type lysozyme, and TNF-α. Moreover, overexpression of Lc-HMGB1 could also induce the expression of IRF7 and Mx. These results collectively indicate that Lc-HMGB1 and Lc-HMGB2 play important roles in host immune responses against pathogen infection.

Immunological Tolerance in Liver Transplant Recipients: Putative Involvement of Neuroendocrine-Immune Interactions

The transplantation world changed significantly following the introduction of immunosuppressants, with millions of people saved. Several physicians have noted that liver recipients that do not take their medication for different reasons became tolerant regarding kidney, heart, and lung transplantations at higher frequencies. Most studies have attempted to explain this phenomenon through unique immunological mechanisms and the fact that the hepatic environment is continuously exposed to high levels of pathogen-associated molecular patterns (PAMPs) or non-pathogenic microorganism-associated molecular patterns (MAMPs) from commensal flora. These components are highly inflammatory in the periphery but tolerated in the liver as part of the normal components that arrive via the hepatic portal vein. These immunological mechanisms are discussed herein based on current evidence, although we hypothesize the participation of neuroendocrine-immune pathways, which have played a relevant role in autoimmune diseases. Cells found in the liver present receptors for several cytokines, hormones, peptides, and neurotransmitters that would allow for system crosstalk. Furthermore, the liver is innervated by the autonomic system and may, thus, be influenced by the parasympathetic and sympathetic systems. This review therefore seeks to discuss classical immunological hepatic tolerance mechanisms and hypothesizes the possible participation of the neuroendocrine-immune system based on the current literature.

A fat body transcriptome analysis of the immune responses of Rhodnius prolixus to artificial infections with bacteria

BACKGROUND

Rhodnius prolixus is an important vector of Trypanosoma cruzi, the causal agent of Chagas disease in humans. Despite the medical importance of this and other triatomine vectors, the study of their immune responses has been limited to a few molecular pathways and processes. Insect immunity studies were first described for holometabolous insects such as Drosophila melanogaster, and it was assumed that their immune responses were conserved in all insects. However, study of the immune responses of triatomines and other hemimetabolous insects has revealed discrepancies between these and the Drosophila model.

METHODS

To expand our understanding of innate immune responses of triatomines to pathogens, we injected fifth instar nymphs of R. prolixus with the Gram-negative (Gr-) bacterium Enterobacter cloacae, the Gram-positive (Gr+) bacterium Staphylococcus aureus, or phosphate-buffered saline (PBS), and evaluated transcript expression in the fat body 8 and 24 h post-injection (hpi). We analyzed the differential expression of transcripts at each time point, and across time, for each treatment.

RESULTS

At 8 hpi, the Gr- bacteria-injected group had a large number of differentially expressed (DE) transcripts, and most of the changes in transcript expression were maintained at 24 hpi. In the Gr+ bacteria treatment, few DE transcripts were detected at 8 hpi, but a large number of transcripts were DE at 24 hpi. Unexpectedly, the PBS control also had a large number of DE transcripts at 24 hpi. Very few DE transcripts were common to the different treatments and time points, indicating a high specificity of the immune responses of R. prolixus to different pathogens. Antimicrobial peptides known to be induced by the immune deficiency pathway were induced upon Gr- bacterial infection. Many transcripts of genes from the Toll pathway that are thought to participate in responses to Gr+ bacteria and fungi were induced by both bacteria and PBS treatment. Pathogen recognition receptors and serine protease cascade transcripts were also overexpressed after Gr- bacteria and PBS injections. Gr- injection also upregulated transcripts involved in the metabolism of tyrosine, a major substrate involved in the melanotic encapsulation response to pathogens.

CONCLUSIONS

These results reveal time-dependent pathogen-specific regulation of immune responses in triatomines, and hint at strong interactions between the immune deficiency and Toll pathways.

Engineering a Therapeutic Protein to Enhance the Study of Anti-Drug Immunity

The development of anti-drug antibodies represents a significant barrier to the utilization of protein-based therapies for a wide variety of diseases. While the rate of antibody formation can vary depending on the therapeutic employed and the target patient population receiving the drug, the antigen-specific immune response underlying the development of anti-drug antibodies often remains difficult to define. This is especially true for patients with hemophilia A who, following exposure, develop antibodies against the coagulation factor, factor VIII (FVIII). Models capable of studying this response in an antigen-specific manner have been lacking. To overcome this challenge, we engineered FVIII to contain a peptide (323-339) from the model antigen ovalbumin (OVA), a very common tool used to study antigen-specific immunity. FVIII with an OVA peptide (FVIII-OVA) retained clotting activity and possessed the ability to activate CD4 T cells specific to OVA323-339 in vitro. When compared to FVIII alone, FVIII-OVA also exhibited a similar level of immunogenicity, suggesting that the presence of OVA323-339 does not substantially alter the anti-FVIII immune response. Intriguingly, while little CD4 T cell response could be observed following exposure to FVIII-OVA alone, inclusion of anti-FVIII antibodies, recently shown to favorably modulate anti-FVIII immune responses, significantly enhanced CD4 T cell activation following FVIII-OVA exposure. These results demonstrate that model antigens can be incorporated into a therapeutic protein to study antigen-specific responses and more specifically that the CD4 T cell response to FVIII-OVA can be augmented by pre-existing anti-FVIII antibodies.

Unraveling the Immune Microenvironment of Thymic Epithelial Tumors: Implications for Autoimmunity and Treatment

Thymic Epithelial Tumors (TETs) represent a rare tumor family, originating from the epithelial component of the thymus gland. Clinicopathologically, they are segregated into six major subtypes, associated with distinct histological features and clinical outcomes. Their emergence and evolution are accompanied by the generation of a complex tumor microenvironment (TME), dominated by phenotypically and functionally divergent immune cellular subsets, in different maturation states and in analogies that vary significantly among different subtypes. These heterogenous leukocyte populations exert either immune-permissive and tumor-suppressive functions or vice versa, and the dynamic equilibrium established among them either dictates the tumor immune milieu towards an immune-tolerance state or enables the development of a productive spontaneous tumoricidal response. The immunologically “hot” microenvironment, defining a significant proportion of TETs, makes them a promising candidate for the implementation of immune checkpoint inhibitors (ICIs). A number of phase I and II clinical trials have already demonstrated significant, type-specific clinical efficacy of PD-L1 inhibitors, even though substantial limitations in their utilization derive from their immune-mediated adverse effects. Moreover, the completed clinical studies involved relatively restricted patient samples and an expansion in the enrolled cohorts is required, so that more trustworthy conclusions regarding the benefit from ICIs in TETs can be extracted.

The Immune Pathogenesis of Acute-On-Chronic Liver Failure and the Danger Hypothesis

Acute-on-chronic liver failure (ACLF) is a group of clinical syndromes related to severe acute liver function impairment and multiple-organ failure caused by various acute triggering factors on the basis of chronic liver disease. Due to its severe condition, rapid progression, and high mortality, it has received increasing attention. Recent studies have shown that the pathogenesis of ACLF mainly includes direct injury and immune injury. In immune injury, cytotoxic T lymphocytes (CTLs), dendritic cells (DCs), and CD4⁺ T cells accumulate in the liver tissue, secrete a variety of proinflammatory cytokines and chemokines, and recruit more immune cells to the liver, resulting in immune damage to the liver tissue, massive hepatocyte necrosis, and liver failure, but the key molecules and signaling pathways remain unclear. The “danger hypothesis” holds that in addition to the need for antigens, damage-associated molecular patterns (DAMPs) also play a very important role in the occurrence of the immune response, and this hypothesis is related to the pathogenesis of ACLF. Here, the research status and development trend of ACLF, as well as the mechanism of action and research progress on various DAMPs in ACLF, are summarized to identify biomarkers that can predict the occurrence and development of diseases or the prognosis of patients at an early stage.

To protect or to kill: A persisting Darwinian immune dilemma

The immune system, which evolved as a protective system, can paradoxically mediate lethal effects when it is over-activated. These effects can be traced back to infected insects and are mainly mediated by phylogenetically old cytokines that have been found already in starfishes and sponges. We hypothesize that these anti-homeostatic effects are important for restricting the cumulative risk of transmission of highly mutating environmental pathogens that may endanger species, particularly when they start to originate and expand. Considering the Darwinian view that evolution is a permanent process, this anti-homeostatic program is preserved and expressed even when there is no risk for the species. Here, we review these aspects and discuss how evolutionary-imposed anti-homeostatic immune programs are expressed during acute and chronic human diseases, which can be further aggravated in the absence of medical interventions. The relevance of early identification of ancestral biomarkers that predict a shift from protective to deleterious immune outcomes is emphasized.

Think Beyond Particle Cytotoxicity: When Self-Cellular Components Released After Immunogenic Cell Death Explain Chronic Disease Development

The prolonged perturbation of the immune system following the release of a plethora of self-molecules (known as damage-associated molecular patterns, DAMPs) by stressed or dying cells triggers acute and chronic pathological responses. DAMPs are commonly released after plasma membrane damage or complete rupture due to immunogenic cell death (ICD), upon numerous stressors including infectious and toxic agents. The set of DAMPs released after ICD include mature proinflammatory cytokines and alarmins, but also polymeric macromolecules. These self-intracellular components are recognized by injured and healthy surrounding cells via innate receptors, and induce upregulation of stress-response mechanisms, including inflammation. In this review, by overstepping the simple toxicological evaluation, we apply ICD and DAMP concepts to silica cytotoxicity, providing new insights on the mechanisms driving the progress and/or the exacerbation of certain SiO2–related pathologies. Finally, by proposing self-DNA as new crucial DAMP, we aim to pave the way for the development of innovative and easy-to-perform predictive tests to better identify the hazard of fine and ultrafine silica particles. Importantly, such mechanisms could be extended to nano/micro plastics and diesel particles, providing strategic advice and reports on their health issues.

IL-1 family cytokines serve as 'activity recognition receptors' for aberrant protease activity indicative of danger

Members of the extended IL-1 cytokine family play key roles as instigators of inflammation in numerous infectious and sterile injury contexts and are highly enriched at barrier surfaces such as the skin, lungs and intestinal mucosa. Because IL-1 family cytokines do not possess conventional ER-golgi trafficking and secretory signals, these cytokines are typically released into the extracellular space due to tissue damage resulting in necrosis, or pathogen detection resulting in pyroptosis. The latter feature, in combination with other factors, suggests that IL-1 family cytokines serve as canonical damage-associated molecular patterns (DAMPs), which instigate inflammation in response to tissue damage. However, IL-1 family cytokines also require a proteolytic activation step and diverse intracellular, extracellular and non-self proteases have been identified that are capable of processing and activating members of this family. This suggests that IL-1 family members function as sentinels for aberrant protease activity, which is frequently associated with infection or tissue damage. Here, we overview the diversity of proteases implicated in the activation of IL-1 family cytokines and suggest that this ancient cytokine family may have evolved to complement 'pattern recognition receptors', by serving as 'activity recognition receptors' enabling the detection of aberrant enzyme activity indicative of 'danger'.

Biological Actions, Implications, and Cautions of Statins Therapy in COVID-19

The Coronavirus Disease 2019 (COVID-19) showed worse prognosis and higher mortality in individuals with obesity. Dyslipidemia is a major link between obesity and COVID-19 severity. Statins as the most common lipid regulating drugs have shown favorable effects in various pathophysiological states. Importantly, accumulating observational studies have suggested that statin use is associated with reduced risk of progressing to severe illness and in-hospital death in COVID-19 patients. Possible explanations underlie these protective impacts include their abilities of reducing cholesterol, suppressing viral entry and replication, anti-inflammation and immunomodulatory effects, as well as anti-thrombosis and anti-oxidative properties. Despite these benefits, statin therapies have side effects that should be considered, such as elevated creatinine kinase, liver enzyme and serum glucose levels, which are already elevated in severe COVID-19. Concerns are also raised whether statins interfere with the efficacy of COVID-19 vaccines. Randomized controlled trials are being conducted worldwide to confirm the values of statin use for COVID-19 treatment. Generally, the results suggest no necessity to discontinue statin use, and no evidence suggesting interference between statins and COVID-19 vaccines. However, concomitant administration of statins and COVID-19 antiviral drug Paxlovid may increase statin exposure and the risk of adverse effects, because most statins are metabolized mainly through CYP3A4 which is potently inhibited by ritonavir, a major component of Paxlovid. Therefore, more clinical/preclinical studies are still warranted to understand the benefits, harms and mechanisms of statin use in the context of COVID-19.

Thrombin Differentially Modulates the Acute Inflammatory Response to Escherichia coli and Staphylococcus aureus in Human Whole Blood

Thrombin plays a central role in thromboinflammatory responses, but its activity is blocked in the common ex vivo human whole blood models, making an ex vivo study of thrombin effects on thromboinflammatory responses unfeasible. In this study, we exploited the anticoagulant peptide Gly-Pro-Arg-Pro (GPRP) that blocks fibrin polymerization to study the effects of thrombin on acute inflammation in response to Escherichia coli and Staphylococcus aureus Human blood was anticoagulated with either GPRP or the thrombin inhibitor lepirudin and incubated with either E. coli or S. aureus for up to 4 h at 37°C. In GPRP-anticoagulated blood, there were spontaneous elevations in thrombin levels and platelet activation, which further increased in the presence of bacteria. Complement activation and the expression of activation markers on monocytes and granulocytes increased to the same extent in both blood models in response to bacteria. Most cytokines were not elevated in response to thrombin alone, but thrombin presence substantially and heterogeneously modulated several cytokines that increased in response to bacterial incubations. Bacterial-induced releases of IL-8, MIP-1α, and MIP-1β were potentiated in the thrombin-active GPRP model, whereas the levels of IP-10, TNF, IL-6, and IL-1β were elevated in the thrombin-inactive lepirudin model. Complement C5-blockade, combined with CD14 inhibition, reduced the overall cytokine release significantly, both in thrombin-active and thrombin-inactive models. Our data support that thrombin itself marginally induces leukocyte-dependent cytokine release in this isolated human whole blood but is a significant modulator of bacteria-induced inflammation by a differential effect on cytokine patterns.

From infection to repair: Understanding the workings of our innate immune cells

In a world filled with microbes, some posing a threat to our body, our immune system is key to living a healthy life. The innate immune system is made of various cell types that act to guard our bodies. Unlike the adaptive immune system that has a specific response, our innate immune system encompasses cells that elicit unspecific immune responses, triggered whenever the right signals are detected. Our understanding of immunity started with the concept of our immune system only responding to "nonself" like the pathogens that invade our body. However, over the past few decades, we have learned that the immune system is more than an on/off switch that recognizes nonself. The innate immune system regularly patrols our bodies for pathogens and tissue damage. Our innate immune system not only seeks to resolve infection but also repair tissue injury, through phagocytosing debris and initiating the release of growth factors. Recently, we are starting to see that it is not just recognizing danger, our innate immune system plays a crucial role in repair. Innate immune cells phenotypically change during repair. In the context of severe injury or trauma, our innate immune system is modified quite drastically to help repair, resulting in reduced infection control. Moreover, these changes in immune cell function can be modified by sex as a biological variable. From past to present, in this overview, we provide a summary of the innate immune cells and pathways in infection and tissue repair. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology.

IFI16-STING-NF-κB signaling controls exogenous mitochondrion-induced endothelial activation

Mitochondria released from injured cells activate endothelial cells (ECs), fostering inflammatory processes, including allograft rejection. The stimulator of interferon genes (STING) senses endogenous mitochondrial DNA, triggering innate immune activation via NF-κB signaling. Here, we show that exogenous mitochondria exposure induces EC STING-NF-κB activation, promoting EC/effector memory T cell adhesion, which is abrogated by NF-κB and STING inhibitors. STING activation in mitochondrion-activated ECs is independent of canonical cGMP-AMP synthetase sensing/signaling, but rather is mediated by interferon gamma-inducible factor 16 (IFI16) and can be inhibited by IFI16 inhibition. Internalized mitochondria undergo mitofusion and STING-dependent mitophagy, leading to selective sequestration of internalized mitochondria. The exposure of donor hearts to exogenous mitochondria activates murine heart ECs in vivo. Collectively, our results suggest that IFI16-STING-NF-κB signaling regulates exogenous mitochondrion-induced EC activation and mitophagy, and exogenous mitochondria foster T cell-mediated CoBRR. These data suggest a novel, donor-directed, therapeutic approach toward mitigating perioperative allograft immunogenicity.

Exploratory Investigation of the Plasma Proteome Associated with the Endotheliopathy of Trauma

BACKGROUND

The endotheliopathy of trauma (EoT) is associated with increased mortality following injury. Herein, we describe the plasma proteome related to EoT in order to provide insight into the role of the endothelium within the systemic response to trauma.

METHODS

99 subjects requiring the highest level of trauma activation were included in the study. Enzyme-linked immunosorbent assays of endothelial and catecholamine biomarkers were performed on admission plasma samples, as well as untargeted proteome quantification utilizing high-performance liquid chromatography and tandem mass spectrometry.

RESULTS

Plasma endothelial and catecholamine biomarker abundance was elevated in EoT. Patients with EoT (n = 62) had an increased incidence of death within 24 h at 21% compared to 3% for non-EoT (n = 37). Proteomic analysis revealed that 52 out of 290 proteins were differentially expressed between the EoT and non-EoT groups. These proteins are involved in endothelial activation, coagulation, inflammation, and oxidative stress, and include known damage-associated molecular patterns (DAMPs) and intracellular proteins specific to several organs.

CONCLUSIONS

We report a proteomic profile of EoT suggestive of a surge of DAMPs and inflammation driving nonspecific activation of the endothelial, coagulation, and complement systems with subsequent end-organ damage and poor clinical outcome. These findings support the utility of EoT as an index of cellular injury and delineate protein candidates for therapeutic intervention.

MiR-26b-5p in small extracellular vesicles derived from dying tumor cells after irradiation enhances the metastasis promoting microenvironment in esophageal squamous cell carcinoma

Radiation therapy is effective in achieving local control in esophageal squamous cell carcinoma; however, changes in the tumor microenvironment induced by radiation can also promote metastasis. Dying tumor cells play vital roles in promoting the survival of living tumor cells; however, few studies have investigated the effects of dying tumor cells on the tumor microenvironment. Since myeloid-derived suppressor cells (MDSCs) and macrophages constitute the pre-metastatic niche (PMN), we used a 4-nitroquinoline-1-oxide induced in situ tumor model to investigate the effects of irradiation on MDSCs and macrophages in esophageal squamous cell carcinoma (ESCC). When primary tumor sites were irradiated, we observed an increase in MDSCs in the spleen and the deposition of PMN components in lung and liver. Enhanced MDSC accumulation and function were induced by small extracellular vesicles (sEVs) isolated from irradiated tumor-bearing mice. The MDSC induction function of sEVs after irradiation was reaffirmed using sEVs derived from ESCC cell lines. The irradiation-induced upregulation of miR-26b-5p in sEVs enhanced MDSC expansion and activation by targeting phosphatase and tensin homolog. Our results first elucidated a mechanism by which dying tumor cells enhanced the deposition of PMN components and potentiated MDSCs in ESCC after irradiation. sEVs played a vital role in mediating signals between the primary tumor and the microenvironment to form a metastasis-promoting microenvironment after irradiation. Furthermore, miR-26b-5p or PI3K/AKT signaling pathway inhibitors should be evaluated in clinical trials in combination with radiotherapy as a strategy to improve outcomes.