mTOR- and HIF-1α-mediated aerobic glycolysis as metabolic basis for trained immunity

Induction of trained immunity using β-glucan and its protective responses in Nile tilapia, Oreochromis niloticus

Emerging and re-emerging diseases in fish cause drastic economic losses in the aquaculture sector. To combat the impact of disease outbreaks and prevent the emergence of infections in culture systems, understanding the advanced strategies for protecting fish against infections is inevitable in fish health research. Therefore, the present study aimed to evaluate the induction of trained immunity and its protective efficacy against Streptococcus agalactiae in tilapia. For this, Nile tilapia and the Tilapia head kidney macrophage primary culture were primed using β-glucan @200 μg/10 g body weight and 10 μg/mL respectively. Expression profiles of the markers of trained immunity and production of metabolites were monitored at different time points, post-priming and training, which depicted enhanced responsiveness. Higher lactate and lactate dehydrogenase (LDH) production in vitro suggests heightened glycolysis induced by priming of the cells using β-glucan. A survival rate of 60% was observed in β-glucan trained fish post challenge with virulent S. agalactiae at an LD50 of 2.6 × 107 cfu/ml, providing valuable insights into promising strategies of trained immunity for combating infections in fish.

Regulation of metabolic microenvironment with a nanocomposite hydrogel for improved bone fracture healing

Bone nonunion poses an urgent clinical challenge that needs to be addressed. Recent studies have revealed that the metabolic microenvironment plays a vital role in fracture healing. Macrophages and bone marrow-derived mesenchymal stromal cells (BMSCs) are important targets for therapeutic interventions in bone fractures. Itaconate is a TCA cycle metabolite that has emerged as a potent macrophage immunomodulator that limits the inflammatory response. During osteogenic differentiation, BMSCs tend to undergo aerobic glycolysis and metabolize glucose to lactate. Copper ion (Cu2+) is an essential trace element that participates in glucose metabolism and may stimulate glycolysis in BMSCs and promote osteogenesis. In this study, we develop a 4-octyl itaconate (4-OI)@Cu@Gel nanocomposite hydrogel that can effectively deliver and release 4-OI and Cu2+ to modulate the metabolic microenvironment and improve the functions of cells involved in the fracture healing process. The findings reveal that burst release of 4-OI reduces the inflammatory response, promotes M2 macrophage polarization, and alleviates oxidative stress, while sustained release of Cu2+ stimulates BMSC glycolysis and osteogenic differentiation and enhances endothelial cell angiogenesis. Consequently, the 4-OI@Cu@Gel system achieves rapid fracture healing in mice. Thus, this study proposes a promising regenerative strategy to expedite bone fracture healing through metabolic reprogramming of macrophages and BMSCs.

Integrating genetic and immune factors to uncover pathogenetic mechanisms of viral-associated pulmonary aspergillosis

Invasive pulmonary aspergillosis is a severe fungal infection primarily affecting immunocompromised patients. Individuals with severe viral infections have recently been identified as vulnerable to developing invasive fungal infections. Both influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA) are linked to high mortality rates, emphasizing the urgent need for an improved understanding of disease pathogenesis to unveil new molecular targets with diagnostic and therapeutic potential. The recent establishment of animal models replicating the co-infection context has offered crucial insights into the mechanisms that underlie susceptibility to disease. However, the development and progression of human viral-fungal co-infections exhibit a significant degree of interindividual variability, even among patients with similar clinical conditions. This observation implies a significant role for host genetics, but information regarding the genetic basis for viral-fungal co-infections is currently limited. In this review, we discuss how genetic factors known to affect either antiviral or antifungal immunity could potentially reveal pathogenetic mechanisms that predispose to IAPA or CAPA and influence the overall disease course. These insights are anticipated to foster further research in both pre-clinical models and human patients, aiming to elucidate the complex pathophysiology of viral-associated pulmonary aspergillosis and contributing to the identification of new diagnostic and therapeutic targets to improve the management of these co-infections.

Tissue-resident trained immunity in hepatocytes protects against septic liver injury in zebrafish

Trained immunity is classically characterized by long-term functional reprogramming of innate immune cells to combat infectious diseases. Infection-induced organ injury is a common clinical severity phenotype of sepsis. However, whether the induction of trained immunity plays a role in protecting septic organ injury remains largely unknown. Here, through establishing an in vivo β-glucan training and lipopolysaccharide (LPS) challenge model in zebrafish larvae, we observe that induction of trained immunity could inhibit pyroptosis of hepatocytes to alleviate septic liver injury, with an elevated trimethyl-histone H3 lysine 4 (H3K4me3) modification that targets mitophagy-related genes. Moreover, we identify a C-type lectin domain receptor in zebrafish, named DrDectin-1, which is revealed as the orchestrator in gating H3K4me3 rewiring-mediated mitophagy activation and alleviating pyroptosis-engaged septic liver injury in vivo. Taken together, our results uncover tissue-resident trained immunity in maintaining liver homeostasis at the whole-animal level and offer an in vivo model to efficiently integrate trained immunity for immunotherapies.

Trained immunity: A link between risk factors and cardiovascular disease

Cardiovascular diseases are significant contributors to human mortality, closely associated with inflammation. With the changing living conditions and the extension of human lifespan, greater attention has been directed towards understanding the impact of early, long-term events on the development of cardiovascular events. Lifestyle factors such as stress, unhealthy diet and physical inactivity can increase the risk of cardiovascular diseases. Interestingly, even if the risk factors are addressed later, their influence may persist. Recently, the concept of trained innate immunity (TRIM), defined as sustained alterations in the function of innate immunocyte that promote a more robust response to downstream stimuli, has been proposed to be involved in cardiovascular diseases. It is hypothesized that TRIM may serve as a mediator bridging the impacts of aforementioned risk factors. This review aims to elucidate the role of TRIM in cardiovascular diseases and highlight its significance in uncovering new mechanisms and therapeutic targets.

Early life vaccination reprograms the metabolism and function of myeloid cells in neonates

Vaccination after birth provides protection against pathogen infection and immune related disorders in healthy children. The detailed effects of vaccination on neonatal immunity, however, remain largely unknown. Here, we reported that vaccination using Bacillus Calmette-Guérin (BCG) diminished the immunosuppressive function of myeloid-derived suppressor cells in neonatal mice, an immature myeloid population. A combination of single-cell transcriptome, metabolite profiling, and functional analysis demonstrated that upregulation of mTOR/HIF1a signalling and the enhanced glycolysis explained the effects of BCG on neonatal myeloid cells. Pharmalogical inhibition of glycolysis or mTOR signalling efficiently rescued the effects of BCG on neonatal myeloid cells. These observations suggest that BCG facilitates the maturation of myeloid cells in early life, which may contribute to its beneficial effects against immune disorders later in life.

Sarcoidosis immunopathogenesis - a new concept of maladaptive trained immunity

Sarcoidosis is a chronic immune disease of unknown origin for which we still lack an immunological framework unifying causal agents, host factors, and natural history of disease. Here, we discuss the initial triggers of disease, and how myeloid cells drive granuloma formation and contribute to immunopathogenesis. We highlight recent advances in our understanding of innate immune memory and propose the hypothesis that maladaptive innate immune training connects previous environmental exposure to granuloma maintenance and expansion. Lastly, we consider how this hypothesis may open novel therapeutic avenues, while corticosteroids remain the front-line treatment.

Forged in the fire: Lasting impacts of inflammation on hematopoietic progenitors

Quiescence and differentiation of hematopoietic stem and progenitor cells (HSPC) can be modified by systemic inflammatory cues. Such cues can not only yield short-term changes in HSPCs such as in supporting emergency granulopoiesis but can also promote lasting influences on the HSPC compartment. First, inflammation can be a driver for clonal expansion, promoting clonal hematopoiesis for certain mutant clones, reducing overall clonal diversity, and reshaping the composition of the HSPC pool with significant health consequences. Second, inflammation can generate lasting cell-autonomous changes in HSPCs themselves, leading to changes in the epigenetic state, metabolism, and function of downstream innate immune cells. This concept, termed "trained immunity," suggests that inflammatory stimuli can alter subsequent immune responses leading to improved innate immunity or, conversely, autoimmunity. Both of these concepts have major implications in human health. Here we reviewed current literature about the lasting effects of inflammation on the HSPC compartment and opportunities for future advancement in this fast-developing field.

Increased expression of CD38 on endothelial cells in SARS-CoV-2 infection in cynomolgus macaques

SARS-CoV-2 infection causes activation of endothelial cells (ECs), leading to dysmorphology and dysfunction. To study the pathogenesis of endotheliopathy, the activation of ECs in lungs of cynomolgus macaques after SARS-CoV-2 infection and changes in nicotinamide adenine dinucleotide (NAD) metabolism in ECs were investigated, with a focus on the CD38 molecule, which degrades NAD in inflammatory responses after SARS-CoV-2 infection. Activation of ECs was seen from day 3 after SARS-CoV-2 infection in macaques, with increases of intravascular fibrin and NAD metabolism-associated enzymes including CD38. In vitro, upregulation of CD38 mRNA in human ECs was detected after interleukin 6 (IL-6) trans-signaling induction, which was increased in the infection. In the presence of IL-6 trans-signaling stimulation, however, CD38 mRNA silencing induced significant IL-6 mRNA upregulation in ECs and promoted EC apoptosis after stimulation. These results suggest that upregulation of CD38 in patients with COVID-19 has a protective role against IL-6 trans-signaling stimulation induced by SARS-CoV-2 infection.

Streptococcus pneumoniae endopeptidase O induces trained immunity and confers protection against various pathogenic infections

Antibiotic resistance and the surge of infectious diseases during the pandemic present significant threats to human health. Trained immunity emerges as a promising and innovative approach to address these infections. Synthetic or natural fungal, parasitic and viral components have been reported to induce trained immunity. However, it is not clear whether bacterial virulence proteins can induce protective trained immunity. Our research demonstrates Streptococcus pneumoniae virulence protein PepO, is a highly potent trained immunity inducer for combating broad-spectrum infection. Our findings showcase that rPepO training confers robust protection to mice against various pathogenic infections by enhancing macrophage functionality. rPepO effectively re-programs macrophages, re-configures their epigenetic modifications and bolsters their immunological responses, which is independent of T or B lymphocytes. In vivo and in vitro experiments confirm that trained macrophage-secreted complement C3 activates peritoneal B lymphocyte and enhances its bactericidal capacity. In addition, we provide the first evidence that granulocyte colony-stimulating factor (G-CSF) derived from trained macrophages plays a pivotal role in shaping central-trained immunity. In summation, our research demonstrates the capability of rPepO to induce both peripheral and central trained immunity in mice, underscoring its potential application in broad-spectrum anti-infection therapy. Our research provides a new molecule and some new target options for infectious disease prevention.

A novel fatty acid metabolism-related signature identifies MUC4 as a novel therapy target for esophageal squamous cell carcinoma

Fatty acid metabolism has been identified as an emerging hallmark of cancer, which was closely associated with cancer prognosis. Whether fatty acid metabolism-related genes (FMGs) signature play a more crucial role in biological behavior of esophageal squamous cell carcinoma (ESCC) prognosis remains unknown. Thus, we aimed to identify a reliable FMGs signature for assisting treatment decisions and prognosis evaluation of ESCC. In the present study, we conducted consensus clustering analysis on 259 publicly available ESCC samples. The clinical information was downloaded from The Cancer Genome Atlas (TCGA, 80 ESCC samples) and Gene Expression Omnibus (GEO) database (GSE53625, 179 ESCC samples). A consensus clustering arithmetic was used to determine the FMGs molecular subtypes, and survival outcomes and immune features were evaluated among the different subtypes. Kaplan-Meier analysis and the receiver operating characteristic (ROC) was applied to evaluate the reliability of the risk model in training cohort, validation cohort and all cohorts. A nomogram to predict patients' 1-year, 3-year and 5-year survival rate was also studied. Finally, CCK-8 assay, wound healing assay, and transwell assay were implemented to evaluate the inherent mechanisms of FMGs for tumorigenesis in ESCC. Two subtypes were identified by consensus clustering, of which cluster 2 is preferentially associated with poor prognosis, lower immune cell infiltration. A fatty acid (FA) metabolism-related risk model containing eight genes (FZD10, TACSTD2, MUC4, PDLIM1, PRSS12, BAALC, DNAJA2 and ALOX12B) was established. High-risk group patients displayed worse survival, higher stromal, immune and ESTIMATE scores than in the low-risk group. Moreover, a nomogram revealed good predictive ability of clinical outcomes in ESCC patients. The results of qRT-PCR analysis revealed that the MUC4 and BAALC had high expression level, and FZD10, PDLIM1, TACSTD2, ALOX12B had low expression level in ESCC cells. In vitro, silencing MUC4 remarkably inhibited ESCC cell proliferation, invasion and migration. Our study fills the gap of FMGs signature in predicting the prognosis of ESCC patients. These findings revealed that cluster subtypes and risk model of FMGs had effects on survival prediction, and were expected to be the potential promising targets for ESCC.

Lactate metabolism and acute kidney injury

ABSTRACT

Acute kidney injury (AKI) is a common clinically critical syndrome in hospitalized patients with high morbidity and mortality. At present, the mechanism of AKI has not been fully elucidated, and no therapeutic drugs exist. As known, glycolytic product lactate is a key metabolite in physiological and pathological processes. The kidney is an important gluconeogenic organ, where lactate is the primary substrate of renal gluconeogenesis in physiological conditions. During AKI, altered glycolysis and gluconeogenesis in kidneys significantly disturb the lactate metabolic balance, which exert impacts on the severity and prognosis of AKI. Additionally, lactate-derived posttranslational modification, namely lactylation, is novel to AKI as it could regulate gene transcription of metabolic enzymes involved in glycolysis or Warburg effect. Protein lactylation widely exists in human tissues and may severely affect non-histone functions. Moreover, the strategies of intervening lactate metabolic pathways are expected to bring a new dawn for the treatment of AKI. This review focused on renal lactate metabolism, especially in proximal renal tubules after AKI, and updated recent advances of lactylation modification, which may help to explore potential therapeutic targets against AKI.

A negative feedback loop underlies the Warburg effect

Aerobic glycolysis, or the Warburg effect, is used by cancer cells for proliferation while producing lactate. Although lactate production has wide implications for cancer progression, it is not known how this effect increases cell proliferation and relates to oxidative phosphorylation. Here, we elucidate that a negative feedback loop (NFL) is responsible for the Warburg effect. Further, we show that aerobic glycolysis works as an amplifier of oxidative phosphorylation. On the other hand, quiescence is an important property of cancer stem cells. Based on the NFL, we show that both aerobic glycolysis and oxidative phosphorylation, playing a synergistic role, are required to achieve cell quiescence. Further, our results suggest that the cells in their hypoxic niche are highly proliferative yet close to attaining quiescence by increasing their NADH/NAD+ ratio through the severity of hypoxia. The findings of this study can help in a better understanding of the link among metabolism, cell cycle, carcinogenesis, and stemness.

Intermittent hyperglycaemia induces macrophage dysfunction by extracellular regulated protein kinase-dependent PKM2 translocation in periodontitis

Early fluctuations in blood glucose levels increased susceptibility to macrophage dysfunction. However, the underlying pathological mechanisms linking glucose variations and macrophage dysregulation remains elusive. In current study, we established an animal model of transient intermittent hyperglycaemia (TIH) to simulate early fluctuations in blood glucose levels. Our findings revealed that both TIH and diabetic group exhibited more severe periodontal lesions and increased secretion of pro-inflammatory cytokines compared to healthy controls. In immortalized bone marrow-derived macrophages (iBMDMs), phagocytosis and chemotaxis were impaired with transient and lasting hyperglycaemia, accompanied by enhanced glycolysis. We also found that TIH activated pyruvate kinase M2 (PKM2) through the phosphorylation of extracellular regulated protein kinase (ERK) in vivo, particularly at dimeric levels. In macrophage cultured with TIH, PKM2 translocated into the nucleus and involved in the regulating inflammatory genes, including TNF-α, IL-6 and IL-1β. PKM2 translocation and secretion of inflammatory cytokines were attenuated by PD98059, while PKM2 tetramer activator TEPP-46 prevented the formation of dimeric PKM2 in macrophages. Moreover, inhibition of glycolysis alleviated the TIH-induced pro-inflammatory cytokines. In conclusion, our manuscript provides a rationale for understanding how TIH modulates metabolic rewiring and dysfunction in macrophages via ERK-dependent PKM2 nuclear translocation.

Mitochondrial transfer in tunneling nanotubes-a new target for cancer therapy

A century ago, the Warburg effect was first proposed, revealing that cancer cells predominantly rely on glycolysis during the process of tumorigenesis, even in the presence of abundant oxygen, shifting the main pathway of energy metabolism from the tricarboxylic acid cycle to aerobic glycolysis. Recent studies have unveiled the dynamic transfer of mitochondria within the tumor microenvironment, not only between tumor cells but also between tumor cells and stromal cells, immune cells, and others. In this review, we explore the pathways and mechanisms of mitochondrial transfer within the tumor microenvironment, as well as how these transfer activities promote tumor aggressiveness, chemotherapy resistance, and immune evasion. Further, we discuss the research progress and potential clinical significance targeting these phenomena. We also highlight the therapeutic potential of targeting intercellular mitochondrial transfer as a future anti-cancer strategy and enhancing cell-mediated immunotherapy.

Metabolic rewiring and communication in cancer immunity

The immune system shapes tumor development and progression. Although immunotherapy has transformed cancer treatment, its overall efficacy remains limited, underscoring the need to uncover mechanisms to improve therapeutic effects. Metabolism-associated processes, including intracellular metabolic reprogramming and intercellular metabolic crosstalk, are emerging as instructive signals for anti-tumor immunity. Here, we first summarize the roles of intracellular metabolic pathways in controlling immune cell function in the tumor microenvironment. How intercellular metabolic communication regulates anti-tumor immunity, and the impact of metabolites or nutrients on signaling events, are also discussed. We then describe how targeting metabolic pathways in tumor cells or intratumoral immune cells or via nutrient-based interventions may boost cancer immunotherapies. Finally, we conclude with discussions on profiling and functional perturbation methods of metabolic activity in intratumoral immune cells, and perspectives on future directions. Uncovering the mechanisms for metabolic rewiring and communication in the tumor microenvironment may enable development of novel cancer immunotherapies.

The cholera toxin B subunit induces trained immunity in dendritic cells and promotes CD8 T cell antitumor immunity

Introduction

Innate immune training is a metabolic, functional, and epigenetic long-term reprogramming of innate cells triggered by different stimuli. This imprinting also reaches hematopoietic precursors in the bone marrow to sustain a memory-like phenotype. Dendritic cells (DCs) can exhibit memory-like responses, enhanced upon subsequent exposure to a pathogen; however, whether this imprinting is lineage and stimulus-restricted is still being determined. Nevertheless, the functional consequences of DCs training on the adaptive and protective immune response against non-infectious diseases remain unresolved.

Methods

We evaluated the effect of the nontoxic cholera B subunit (CTB), LPS and LTA in the induction of trained immunity in murine DCs revealed by TNFa and LDH expression, through confocal microscopy. Additionally, we obtained bone marrow DCs (BMDCs) from mice treated with CTB, LPS, and LTA and evaluated training features in DCs and their antigen-presenting cell capability using multiparametric cytometry. Finally, we design an experimental melanoma mouse model to demonstrate protection induced by CTB-trained DCs in vivo.

Results

CTB-trained DCs exhibit increased expression of TNFa, and metabolic reprogramming indicated by LDH expression. Moreover, CTB training has an imprint on DC precursors, increasing the number and antigen-presenting function in BMDCs. We found that training by CTB stimulates the recruitment of DC precursors and DCs infiltration at the skin and lymph nodes. Interestingly, training-induced by CTB promotes a highly co-stimulatory phenotype in tumor-infiltrating DCs (CD86+) and a heightened functionality of exhausted CD8 T cells (Ki67+, GZMB+), which were associated with a protective response against melanoma challenge in vivo.

Conclusion

Our work indicates that CTB can induce innate immune training on DCs, which turns into an efficient adaptive immune response in the melanoma model and might be a potential immunotherapeutic approach for tumor growth control.

Integrating population and single-cell variations in vaccine responses identifies a naturally adjuvanted human immune setpoint

Multimodal single-cell profiling methods can capture immune cell variations unfolding over time at the molecular, cellular, and population levels. Transforming these data into biological insights remains challenging. Here, we introduce a framework to integrate variations at the human population and single-cell levels in vaccination responses. Comparing responses following AS03-adjuvanted versus unadjuvanted influenza vaccines with CITE-seq revealed AS03-specific early (day 1) response phenotypes, including a B cell signature of elevated germinal center competition. A correlated network of cell-type-specific transcriptional states defined the baseline immune status associated with high antibody responders to the unadjuvanted vaccine. Certain innate subsets in the network appeared "naturally adjuvanted," with transcriptional states resembling those induced uniquely by AS03-adjuvanted vaccination. Consistently, CD14+ monocytes from high responders at baseline had elevated phospho-signaling responses to lipopolysaccharide stimulation. Our findings link baseline immune setpoints to early vaccine responses, with positive implications for adjuvant development and immune response engineering.

Oroxylin A-induced Trained Immunity Promotes LC3-associated Phagocytosis in Macrophage in Protecting Mice Against Sepsis

Sepsis is defined as a dysregulated host response to infection that leads to multiorgan failure. Innate immune memory, i.e., "trained immunity", can result in stronger immune responses and provide protection against various infections. Many biological agents, including β-glucan, can induce trained immunity, but these stimuli may cause uncontrolled inflammation. Oroxylin A (OA) is an active flavonoid compound that is derived from Scutellaria baicalensis. OA is an agonist for inducing trained immunity in vivo and in vitro, and β-glucan was used as a positive control. The protective effects of OA-induced trained immunity were evaluated in mouse models that were established by either lipopolysaccharide (LPS) administration or caecal ligation and puncture (CLP). The expression of inflammatory factors and signaling pathway components involved in trained immunity was evaluated in vitro using qRT‒PCR, western blotting (WB) and enzyme-linked immunosorbent assay (ELISA). Flow cytometry and confocal microscopy were used to examine reactive oxygen species (ROS) levels and phagocytosis in trained macrophages. A PCR array was used to screen genes that were differentially expressed in trained macrophages. Here, we revealed that OA alleviated sepsis via trained immunity. OA-treated macrophages displayed increased glycolysis and mTOR phosphorylation, and mTOR inhibitors suppressed OA-induced trained immunity by effectively reprogramming macrophages. The PCR array revealed key genes in the mTOR signaling pathway in OA-treated macrophages. Furthermore, OA targeted the Dectin-1-syk axis to promote LC3-associated phagocytosis (LAP) by trained macrophages, thereby enhancing the ability of these macrophages to protect against infection. This ability could be transferred to a new host via the adoptive transfer of peritoneal macrophages. This study is the first to provide new insights into the potential of OA-induced trained immunity to be used as a strategy to protect mice against sepsis by promoting LAP by macrophages.

GDF15 ameliorates sepsis-induced lung injury via AMPK-mediated inhibition of glycolysis in alveolar macrophage

Growth differentiation factor 15 (GDF15) as a stress response cytokine is involved in the development and progression of several diseases associated with metabolic disorders. However, the regulatory role and the underlying mechanisms of GDF15 in sepsis remain poorly defined. Our study analyzed the levels of GDF15 and its correlations with the clinical prognosis of patients with sepsis. In vivo and in vitro models of sepsis were applied to elucidate the role and mechanisms of GDF15 in sepsis-associated lung injury. We observed strong correlations of plasma GDF15 levels with the levels of C-reactive protein (CRP), procalcitonin (PCT), lactate dehydrogenase (LDH), and lactate as well as Sequential Organ Failure Assessment (SOFA) scores in patients with sepsis. In the mouse model of lipopolysaccharide-induced sepsis, recombinant GDF15 inhibited the proinflammatory responses and alleviated lung tissue injury. In addition, GDF15 decreased the levels of cytokines produced by alveolar macrophages (AMs). The anti-inflammatory effect of glycolysis inhibitor 2-DG on AMs during sepsis was mediated by GDF15 via inducing the phosphorylation of the α-subunit of eukaryotic initiation factor 2 (eIF2α) and the expression of activating transcription factor 4 (ATF4). Furthermore, we explored the mechanism underlying the beneficial effects of GDF15 and found that GDF15 inhibited glycolysis and mitogen-activated protein kinases (MAPK)/nuclear factor-κB (NF-κB) signaling via promoting AMPK phosphorylation. This study demonstrated that GDF15 inhibited glycolysis and NF-κB/MAPKs signaling via activating AMP-activated protein kinase (AMPK), thereby alleviating the inflammatory responses of AMs and sepsis-associated lung injury. Our findings provided new insights into novel therapeutic strategies for treating sepsis.

Inflammatory tissue priming: novel insights and therapeutic opportunities for inflammatory rheumatic diseases

Due to optimised treatment strategies and the availability of new therapies during the last decades, formerly devastating chronic inflammatory diseases such as rheumatoid arthritis or systemic sclerosis (SSc) have become less menacing. However, in many patients, even state-of-the-art treatment cannot induce remission. Moreover, the risk for flares strongly increases once anti-inflammatory therapy is tapered or withdrawn, suggesting that underlying pathological processes remain active even in the absence of overt inflammation. It has become evident that tissues have the ability to remember past encounters with pathogens, wounds and other irritants, and to react more strongly and/or persistently to the next occurrence. This priming of the tissue bears a paramount role in defence from microbes, but on the other hand drives inflammatory pathologies (the Dr Jekyll and Mr Hyde aspect of tissue adaptation). Emerging evidence suggests that long-lived tissue-resident cells, such as fibroblasts, macrophages, long-lived plasma cells and tissue-resident memory T cells, determine inflammatory tissue priming in an interplay with infiltrating immune cells of lymphoid and myeloid origin, and with systemically acting factors such as cytokines, extracellular vesicles and antibodies. Here, we review the current state of science on inflammatory tissue priming, focusing on tissue-resident and tissue-occupying cells in arthritis and SSc, and reflect on the most promising treatment options targeting the maladapted tissue response during these diseases.

Dihydroartemisinin is an inhibitor of trained immunity through Akt/mTOR/HIF1α signaling pathway

Trained immunity is mechanistically defined as the metabolically and epigenetically mediated long-term functional adaptation of the innate immune system, characterized by a heightened response to a secondary stimulation. Given appropriate activation, trained immunity represents an attractive anti-infective therapeutic target. Nevertheless, excessive immune response and subsequent inflammatory cascades may contribute to pathological tissue damage, indicating that the negative impacts of trained immunity appear to be significant. In this study, we show that innate immune responses such as the production of extracellular traps, pro-inflammatory cytokines, and autophagy-related proteins were markedly augmented in trained BMDMs. Furthermore, heat-killed C. albicans priming promotes the activation of the AIM2 inflammasome, and AIM2-/- mice exhibit impaired memory response induced by heat-killed C. albicans. Therefore, we establish that the AIM2 inflammasome is involved in trained immunity and emerges as a promising therapeutic target for potentially deleterious effects. Dihydroartemisinin can inhibit the memory response induced by heat-killed C. albicans through modulation of mTOR signaling and the AIM2 inflammasome. The findings suggest that dihydroartemisinin can reduce the induction of trained immunity by heat-killed C. albicans in C57BL/6 mice. Dihydroartemisinin is one such therapeutic intervention that has the potential to treat of diseases characterized by excessive trained immunity.

Discovering adaptive features of innate immune memory

Conventionally, it was thought that innate immunity operated through a simple system of nonspecific responses to an insult. However, this perspective now seems overly simplistic. It has become evident that intricate cooperation and networking among various cells, receptors, signaling pathways, and protein complexes are essential for regulating and defining the overall activation status of the immune response, where the distinction between innate and adaptive immunity becomes ambiguous. Given the evolutionary timeline of vertebrates and the success of plants and invertebrates which depend solely on innate immunity, immune memory cannot be considered an innovation of only the lymphoid lineage. Indeed, the evolutionary innate immune memory program is a conserved mechanism whereby innate immune cells can induce a heightened response to a secondary stimulus due to metabolic and epigenetic reprogramming. Importantly, the longevity of this memory phenotype can be attributed to the reprogramming of self-renewing hematopoietic stem cells (HSCs) in the bone marrow, which is subsequently transmitted to lineage-committed innate immune cells. HSCs reside within a complex regulated network of immune and stromal cells that govern their two primary functions: self-renewal and differentiation. In this review, we delve into the emerging cellular and molecular mechanisms as well as metabolic pathways of innate memory in HSCs, which harbor substantial therapeutic promise.

Shaping immunity: The influence of natural selection on population immune diversity

Humans exhibit considerable variability in their immune responses to the same immune challenges. Such variation is widespread and affects individual and population-level susceptibility to infectious diseases and immune disorders. Although the factors influencing immune response diversity are partially understood, what mechanisms lead to the wide range of immune traits in healthy individuals remain largely unexplained. Here, we discuss the role that natural selection has played in driving phenotypic differences in immune responses across populations and present-day susceptibility to immune-related disorders. Further, we touch on future directions in the field of immunogenomics, highlighting the value of expanding this work to human populations globally, the utility of modeling the immune response as a dynamic process, and the importance of considering the potential polygenic nature of natural selection. Identifying loci acted upon by evolution may further pinpoint variants critically involved in disease etiology, and designing studies to capture these effects will enrich our understanding of the genetic contributions to immunity and immune dysregulation.

Metabolomics at the tumor microenvironment interface: Decoding cellular conversations

Cancer heterogeneity remains a significant challenge for effective cancer treatments. Altered energetics is one of the hallmarks of cancer and influences tumor growth and drug resistance. Studies have shown that heterogeneity exists within the metabolic profile of tumors, and personalized-combination therapy with relevant metabolic interventions could improve patient response. Metabolomic studies are identifying novel biomarkers and therapeutic targets that have improved treatment response. The spatial location of elements in the tumor microenvironment are becoming increasingly important for understanding disease progression. The evolution of spatial metabolomics analysis now allows scientists to deeply understand how metabolite distribution contributes to cancer biology. Recently, these techniques have spatially resolved metabolite distribution to a subcellular level. It has been proposed that metabolite mapping could improve patient outcomes by improving precision medicine, enabling earlier diagnosis and intraoperatively identifying tumor margins. This review will discuss how altered metabolic pathways contribute to cancer progression and drug resistance and will explore the current capabilities of spatial metabolomics technologies and how these could be integrated into clinical practice to improve patient outcomes.

Epigenetic control of microglial immune responses

Microglia, the major population of brain-resident macrophages, are now recognized as a heterogeneous population comprising several cell subtypes with different (so far mostly supposed) functions in health and disease. A number of studies have performed molecular characterization of these different microglial activation states over the last years making use of "omics" technologies, that is transcriptomics, proteomics and, less frequently, epigenomics profiling. These approaches offer the possibility to identify disease mechanisms, discover novel diagnostic biomarkers, and develop new therapeutic strategies. Here, we focus on epigenetic profiling as a means to understand microglial immune responses beyond what other omics methods can offer, that is, revealing past and present molecular responses, gene regulatory networks and potential future response trajectories, and defining cell subtype-specific disease relevance through mapping non-coding genetic variants. We review the current knowledge in the field regarding epigenetic regulation of microglial identity and function, provide an exemplary analysis that demonstrates the advantages of performing joint transcriptomic and epigenomic profiling of single microglial cells and discuss how comprehensive epigenetic analyses may enhance our understanding of microglial pathophysiology.

Trained immunity: General and emerging concepts

Over the past decade, compelling evidence has unveiled previously overlooked adaptive characteristics of innate immune cells. Beyond their traditional role in providing short, non-specific protection against pathogens, innate immune cells can acquire antigen-agnostic memory, exhibiting increased responsiveness to secondary stimulation. This long-term de-facto innate immune memory, also termed trained immunity, is mediated through extensive metabolic rewiring and epigenetic modifications. While the upregulation of trained immunity proves advantageous in countering immune paralysis, its overactivation contributes to the pathogenesis of autoinflammatory and autoimmune disorders. In this review, we present the latest advancements in the field of innate immune memory followed by a description of the fundamental mechanisms underpinning trained immunity generation and different cell types that mediate it. Furthermore, we explore its implications for various diseases and examine current limitations and its potential therapeutic targeting in immune-related disorders.

Enduring echoes: Post-infectious long-term changes in innate immunity

Upon encountering pathogens, the immune system typically responds by initiating an acute and self-limiting reaction, with symptoms subsiding after the pathogen has been cleared. However, long-term post-infectious clinical symptoms can manifest months or even years after the initial infection. 'Trained immunity', the functional reprogramming of innate immune cells through epigenetic and metabolic rewiring, has been proposed as a key concept for understanding these long-term effects. Although trained immunity can result in enhanced protection against reinfection with heterologous pathogens, it can also contribute to detrimental outcomes. Persisting and excessive inflammation can cause tissue damage and aggravate immune-mediated conditions and cardiovascular complications. On the other hand, suppression of immune cell effector functions by long-lasting epigenetic changes can result in post-infectious immune paralysis. Distinct stimuli can evoke different trained immunity programs, potentially resulting in different consequences for the host. In this review, we provide an overview of both the adaptive and maladaptive consequences of infectious diseases. We discuss how long-term immune dysregulation in patients can be addressed by tailoring host-directed interventions and identify areas of scientific and therapeutic potential to advance further.

Metabolic rewiring promotes anti-inflammatory effects of glucocorticoids

Glucocorticoids represent the mainstay of therapy for a broad spectrum of immune-mediated inflammatory diseases. However, the molecular mechanisms underlying their anti-inflammatory mode of action have remained incompletely understood1. Here we show that the anti-inflammatory properties of glucocorticoids involve reprogramming of the mitochondrial metabolism of macrophages, resulting in increased and sustained production of the anti-inflammatory metabolite itaconate and consequent inhibition of the inflammatory response. The glucocorticoid receptor interacts with parts of the pyruvate dehydrogenase complex whereby glucocorticoids provoke an increase in activity and enable an accelerated and paradoxical flux of the tricarboxylic acid (TCA) cycle in otherwise pro-inflammatory macrophages. This glucocorticoid-mediated rewiring of mitochondrial metabolism potentiates TCA-cycle-dependent production of itaconate throughout the inflammatory response, thereby interfering with the production of pro-inflammatory cytokines. By contrast, artificial blocking of the TCA cycle or genetic deficiency in aconitate decarboxylase 1, the rate-limiting enzyme of itaconate synthesis, interferes with the anti-inflammatory effects of glucocorticoids and, accordingly, abrogates their beneficial effects during a diverse range of preclinical models of immune-mediated inflammatory diseases. Our findings provide important insights into the anti-inflammatory properties of glucocorticoids and have substantial implications for the design of new classes of anti-inflammatory drugs.

Endotoxin tolerance and trained immunity: breaking down immunological memory barriers

For decades, innate immune cells were considered unsophisticated first responders, lacking the adaptive memory of their T and B cell counterparts. However, mounting evidence demonstrates the surprising complexity of innate immunity. Beyond quickly deploying specialized cells and initiating inflammation, two fascinating phenomena - endotoxin tolerance (ET) and trained immunity (TI) - have emerged. ET, characterized by reduced inflammatory response upon repeated exposure, protects against excessive inflammation. Conversely, TI leads to an enhanced response after initial priming, allowing the innate system to mount stronger defences against subsequent challenges. Although seemingly distinct, these phenomena may share underlying mechanisms and functional implications, blurring the lines between them. This review will delve into ET and TI, dissecting their similarities, differences, and the remaining questions that warrant further investigation.

Identification of Indicator Genes for Agar Accumulation in Gracilariopsis lemaneiformis (Rhodophyta)

Agar, as a seaweed polysaccharide mainly extracted from Gracilariopsis lemaneiformis, has been commercially applied in multiple fields. To investigate factors indicating the agar accumulation in G. lemaneiformis, the agar content, soluble polysaccharides content, and expression level of 11 genes involved in the agar biosynthesis were analysed under 4 treatments, namely salinity, temperature, and nitrogen and phosphorus concentrations. The salinity exerted the greatest impact on the agar content. Both high (40‱) and low (10‱, 20‱) salinity promoted agar accumulation in G. lemaneiformis by 4.06%, 2.59%, and 3.00%, respectively. The content of agar as a colloidal polysaccharide was more stable than the soluble polysaccharide content under the treatments. No significant correlation was noted between the two polysaccharides, and between the change in the agar content and the relative growth rate of the algae. The expression of all 11 genes was affected by the 4 treatments. Furthermore, in the cultivar 981 with high agar content (21.30 ± 0.95%) compared to that (16.23 ± 1.59%) of the wild diploid, the transcriptional level of 9 genes related to agar biosynthesis was upregulated. Comprehensive analysis of the correlation between agar accumulation and transcriptional level of genes related to agar biosynthesis in different cultivation conditions and different species of G. lemaneiformis, the change in the relative expression level of glucose-6-phosphate isomerase II (gpiII), mannose-6-phosphate isomerase (mpi), mannose-1-phosphate guanylyltransferase (mpg), and galactosyltransferase II (gatII) genes was highly correlated with the relative agar accumulation. This study lays a basis for selecting high-yield agar strains, as well as for targeted breeding, by using gene editing tools in the future.

Ischemia does not provoke the full immune training repertoire in human cardiac fibroblasts

Trained immunity of monocytes, endothelial, and smooth muscle cells augments the cytokine response to secondary stimuli. Immune training is characterized by stabilization of hypoxia-inducible factor (HIF)-1α, mTOR activation, and aerobic glycolysis. Cardiac fibroblast (CF)-myofibroblast transition upon myocardial ischemia/reperfusion (I/R) features epigenetic and metabolic adaptations reminiscent of trained immunity. We assessed the impact of I/R on characteristics of immune training in human CF and mouse myocardium. I/R was simulated in vitro with transient metabolic inhibition. CF primed with simulated I/R or control buffer were 5 days later re-stimulated with Pam3CSK for 24 h. Mice underwent transient left anterior descending artery occlusion or sham operation with reperfusion for up to 5 days. HIF-regulated metabolic targets and cytokines were assessed by qPCR, immunoblot, and ELISA and glucose consumption, lactate release, and lactate dehydrogenase (LDH) by chromogenic assay. Simulated I/R increased HIF-1α stabilization, mTOR phosphorylation, glucose consumption, lactate production, and transcription of PFKB3 and F2RL3, a HIF-regulated target gene, in human CF. PGK1 and LDH mRNAs were suppressed. Intracellular LDH transiently increased after simulated I/R, and extracellular LDH showed sustained elevation. I/R priming increased abundance of pro-caspase-1, auto-cleaved active caspase-1, and the expression and secretion of interleukin (IL)-1β, but did not augment Pam3CSK-stimulated cytokine transcription or secretion. Myocardial I/R in vivo increased abundance of HIF-1 and the precursor and cleaved forms of caspase-1, caspase-11, and caspase-8, but not of LDH-A or phospho-mTOR. I/R partially reproduces features of immune training in human CF, specifically HIF-1α stabilization, aerobic glycolysis, mTOR phosphorylation, and PFKB3 transcription. I/R does not augment PGK1 or LDH expression or the cytokine response to Pam3CSK. Regulation of PAR4 and inflammasome caspases likely occurs independently of an immune training repertoire.

Squalene-epoxidase-catalyzed 24(S),25-epoxycholesterol synthesis promotes trained-immunity-mediated antitumor activity

The importance of trained immunity in antitumor immunity has been increasingly recognized, but the underlying metabolic regulation mechanisms remain incompletely understood. In this study, we find that squalene epoxidase (SQLE), a key enzyme in cholesterol synthesis, is required for β-glucan-induced trained immunity in macrophages and ensuing antitumor activity. Unexpectedly, the shunt pathway, but not the classical cholesterol synthesis pathway, catalyzed by SQLE, is required for trained immunity induction. Specifically, 24(S),25-epoxycholesterol (24(S),25-EC), the shunt pathway metabolite, activates liver X receptor and increases chromatin accessibility to evoke innate immune memory. Meanwhile, SQLE-induced reactive oxygen species accumulation stabilizes hypoxia-inducible factor 1α protein for metabolic switching into glycolysis. Hence, our findings identify 24(S),25-EC as a key metabolite for trained immunity and provide important insights into how SQLE regulates trained-immunity-mediated antitumor activity.

mTOR signaling pathway regulation HIF-1 α effects on LPS induced intestinal mucosal epithelial model damage

BACKGROUND

Sepsis-induced small-intestinal injury is associated with increased morbidity and mortality. Our previous study and other papers have shown that HIF-1α has a protective effect on intestinal mucosal injury in septic rats. The purpose of this study is to further verify the protective effect of HIF-1α on intestinal mucosa and its molecular mechanism in vitro experiments.

METHODS

Caco-2 cells were selected and experiment was divided into 2 parts. Part I: HIF-1α activator and inhibitor were used to treat lipopolysacchrides (LPS)-stimulated Caco-2 cells respectively, to explore the effect of HIF-1α on LPS induced Caco-2 cell epithelial model; Part II: mTOR activator or inhibitor combined with or without HIF-1α activator, inhibitor to treat LPS-stimulated Caco-2 cells respectively, and then the molecular mechanism of HIF-1α reducing LPS induced Caco-2 cell epithelial model damage was detected.

RESULTS

The results showed that HIF-1α activator decreased the permeability and up regulated tight junction (TJ) expression, while HIF-1α inhibitor had the opposite effect with the HIF-1α activator. mTOR activation increased, while mTOR inhibition decreased HIF-1α protein and expression of its downstream target molecules, which can be attenuated by HIF-1α activator or inhibitor.

CONCLUSION

This study once again confirmed that HIF-1α alleviates LPS-induced mucosal epithelial model damage through P70S6K signalling pathway. It is of great value to explore whether HIF-2α plays crucial roles in the regulation of mucosal epithelial model functions in the future.

Exosomal mediators in sepsis and inflammatory organ injury: unraveling the role of exosomes in intercellular crosstalk and organ dysfunction

Sepsis, a severe systemic inflammatory response to infection, remains a leading cause of morbidity and mortality worldwide. Exosomes, as mediators of intercellular communication, play a pivotal role in the pathogenesis of sepsis through modulating immune responses, metabolic reprogramming, coagulopathy, and organ dysfunction. This review highlights the emerging significance of exosomes in these processes. Initially, it provides an in-depth insight into exosome biogenesis and characterization, laying the groundwork for understanding their diverse and intricate functions. Subsequently, it explores the regulatory roles of exosomes in various immune cells such as neutrophils, macrophages, dendritic cells, T cells, and B cells. This analysis elucidates how exosomes are pivotal in modulating immune responses, thus contributing to the complexity of sepsis pathophysiology. Additionally, this review delves into the role of exosomes in the regulation of metabolism and subsequent organ dysfunction in sepsis. It also establishes a connection between exosomes and the coagulation cascade, which affects endothelial integrity and promotes thrombogenesis in sepsis. Moreover, the review discusses the dual role of exosomes in the progression and resolution of sepsis, exploring their complex involvement in inflammation and healing processes. Furthermore, it underscores their potential as biomarkers and therapeutic targets. Understanding these mechanisms presents new opportunities for novel interventions to mitigate the severe outcomes of sepsis, emphasizing the therapeutic promise of exosome research in critical care settings.

Novel insights into macrophage immunometabolism in nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH), an inflammatory subtype of nonalcoholic fatty liver disease (NAFLD), is characterized by liver steatosis, inflammation, hepatocellular injury and different degrees of fibrosis, and has been becoming the leading cause of liver-related morbidity and mortality worldwide. Unfortunately, the pathogenesis of NASH has not been completely clarified, and there are no approved therapeutic drugs. Recent accumulated evidences have revealed the involvement of macrophage in the regulation of host liver steatosis, inflammation and fibrosis, and different phenotypes of macrophages have different metabolic characteristics. Therefore, targeted regulation of macrophage immunometabolism may contribute to the treatment and prognosis of NASH. In this review, we summarized the current evidences of the role of macrophage immunometabolism in NASH, especially focused on the related function conversion, as well as the strategies to promote its polarization balance in the liver, and hold promise for macrophage immunometabolism-targeted therapies in the treatment of NASH.

HBO regulates the Warburg effect of hypoxic HCC cells through miR-103a-3p/TRIM35

BACKGROUND

There are a lot of studies on the treatment of tumors with hyperbaric oxygen, while most of them are in breast cancer, prostate cancer and so on. However, there are still few studies on hyperbaric oxygen in treating hepatocellular carcinoma (HCC). According to the current data, hyperbaric oxygen is an effective means to intervene in tumors. The Warburg effect is a unique marker of glucose metabolism in tumors related to hypoxia, making it possible for hyperbaric oxygen to interfere with the tumor through the Warburg effect.

METHOD

We used the hypoxia/hyperbaric oxygen(HBO)-exposed HCC cells for in vitro studies. Glucose uptake, lactic acid, and adenosine triphosphate (ATP) assessed the Warburg effect. The expression of miR-103a-3p in HCC was detected by using qRT-PCR. The effect of miR-103a-3p/TRIM35 expression level on the cells was measured using the CCK8 method and flow cytometry. The molecular biological mechanism of miR-103a-3p in HCC was examined using the luciferase reporter, MS2-RIP assays.

RESULT

HBO inhibited the Warburg effect in hypoxic HCC cells. HBO suppressed the expression of miR-103a-3p in hypoxic HCC cells, and miR-103a-3p inhibited the expression of TRIM35 in hypoxic HCC cells. With HBO exposure, miR-103a-3p/TRIM35 regulated the Warburg effect of hypoxic HCC cells.

CONCLUSION

These findings reveal that HBO regulates the Warburg effect of hypoxic HCC cells through miR-103a-3p/TRIM35 and inhibits tumor growth.

Establishment of an in vitro model of monocyte-like THP-1 cells for trained immunity induced by bacillus Calmette-Guérin

BACKGROUND

Mycobacteria bloodstream infections are common in immunocompromised people and usually have disastrous consequences. As the primary phagocytes in the bloodstream, monocytes and neutrophils play critical roles in the fight against bloodstream mycobacteria infections. In contrast to macrophages, the responses of monocytes infected with the mycobacteria have been less investigated.

RESULTS

In this study, we first established a protocol for infection of non-adherent monocyte-like THP-1 cells (i.e. without the differentiation induced by phorbol 12-myristate 13-acetate (PMA) by bacillus Calmette-Guérin (BCG). Via the protocol, we were then capable of exploring the global transcriptomic profiles of non-adherent THP-1 cells infected with BCG, and found that NF-κB, MAPK and PI3K-Akt signaling pathways were enhanced, as well as some inflammatory chemokine/cytokine genes (e.g. CCL4, CXCL10, TNF and IL-1β) were up-regulated. Surprisingly, the Akt-HIF-mTOR signaling pathway was also activated, which induces trained immunity. In this in vitro infection model, increased cytokine responses to lipopolysaccharides (LPS) restimulation, higher cell viability, and decreased Candida albicans loads were observed.

CONCLUSIONS

We have first characterized the transcriptomic profiles of BCG-infected non-adherent THP-1 cells, and first developed a trained immunity in vitro model of the cells.

Breaking Barriers: Modulation of Tumor Microenvironment to Enhance Bacillus Calmette-Guérin Immunotherapy of Bladder Cancer

The clinical management of bladder cancer continues to present significant challenges. Bacillus Calmette-Guérin (BCG) immunotherapy remains the gold standard of treatment for non-muscle invasive bladder cancer (NMIBC), but many patients develop recurrence and progression to muscle-invasive disease (MIBC), which is resistant to BCG. This review focuses on the immune mechanisms mobilized by BCG in bladder cancer tumor microenvironments (TME), mechanisms of BCG resistance, the dual role of the BCG-triggered NFkB/TNFα/PGE2 axis in the regulation of anti-tumor and tumor-promoting aspects of inflammation, and emerging strategies to modulate their balance. A better understanding of BCG resistance will help develop new treatments and predictive biomarkers, paving the way for improved clinical outcomes in bladder cancer patients.

PROTEIN L-ISOASPARTYL METHYLTRANSFERASE protects enolase dysfunction by repairing isoaspartyl-induced damage and is positively implicated in agronomically important seed traits

The protein-repairing enzyme (PRE) PROTEIN L-ISOASPARTYL METHYLTRANSFERASE (PIMT) influences seed vigor by repairing isoaspartyl-mediated protein damage in seeds. However, PIMTs function in other seed traits, and the mechanisms by which PIMT affects such seed traits are still poorly understood. Herein, through molecular, biochemical, and genetic studies using overexpression and RNAi lines in Oryza sativa and Arabidopsis thaliana, we demonstrate that PIMT not only affects seed vigor but also affects seed size and weight by modulating enolase (ENO) activity. We have identified ENO2, a glycolytic enzyme, as a PIMT interacting protein through Y2H cDNA library screening, and this interaction was further validated by BiFC and co-immunoprecipitation assay. We show that mutation or suppression of ENO2 expression results in reduced seed vigor, seed size, and weight. We also proved that ENO2 undergoes isoAsp modification that affects its activity in both in vivo and in vitro conditions. Further, using MS/MS analyses, amino acid residues that undergo isoAsp modification in ENO2 were identified. We also demonstrate that PIMT repairs such isoAsp modification in ENO2 protein, protecting its vital cellular functions during seed maturation and storage, and plays a vital role in regulating seed size, weight, and seed vigor. Taken together, our study identified ENO2 as a novel substrate of PIMT, and both ENO2 and PIMT in turn implicate in agronomically important seed traits.

STING-dependent trained immunity contributes to host defense against Clostridium perfringens infection via mTOR signaling

Clostridium perfringens (C. perfringens) infection is recognized as one of the most challenging issues threatening food safety and perplexing agricultural development. To date, the molecular mechanisms of the interactions between C. perfringens and the host remain poorly understood. Here, we show that stimulator of interferon genes (STING)-dependent trained immunity protected against C. perfringens infection through mTOR signaling. Heat-killed Candida albicans (HKCA) training elicited elevated TNF-α and IL-6 production after LPS restimulation in mouse peritoneal macrophages (PM). Although HKCA-trained PM produced decreased levels of TNF-α and IL-6, the importance of trained immunity was demonstrated by the fact that HKCA training resulted in enhanced bacterial phagocytic ability and clearance in vivo and in vitro during C. perfringens infection. Interestingly, HKCA training resulted in the activation of STING signaling. We further demonstrate that STING agonist DMXAA is a strong inducer of trained immunity and conferred host resistance to C. perfringens infection in PM. Importantly, corresponding to higher bacterial burden, reduction in cytokine secretion, phagocytosis, and bacterial killing were shown in the absence of STING after HKCA training. Meanwhile, the high expression levels of AKT/mTOR/HIF1α were indeed accompanied by an activated STING signaling under HKCA or DMXAA training. Moreover, inhibiting mTOR signaling with rapamycin dampened the trained response to LPS and C. perfringens challenge in wild-type (WT) PM after HKCA training. Furthermore, STING‑deficient PM presented decreased levels of mTOR signaling-related proteins. Altogether, these results support STING involvement in trained immunity which protects against C. perfringens infection via mTOR signaling.

Thrombocytopenia Independently Leads to Changes in Monocyte Immune Function

BACKGROUND

While platelets have well-studied hemostatic functions, platelets are immune cells that circulate at the interface between the vascular wall and white blood cells. The physiological implications of these constant transient interactions are poorly understood. Activated platelets induce and amplify immune responses, but platelets may also maintain immune homeostasis in healthy conditions, including maintaining vascular integrity and T helper cell differentiation, meaning that platelets are central to both immune responses and immune quiescence. Clinical data have shown an association between low platelet counts (thrombocytopenia) and immune dysfunction in patients with sepsis and extracorporeal membrane oxygenation, further implicating platelets as more holistic immune regulators, but studies of platelet immune functions in nondisease contexts have had limited study.

METHODS

We used in vivo models of thrombocytopenia and in vitro models of platelet and monocyte interactions, as well as RNA-seq and ATAC-seq (assay for transposase-accessible chromatin with sequencing), to mechanistically determine how resting platelet and monocyte interactions immune program monocytes.

RESULTS

Circulating platelets and monocytes interact in a CD47-dependent manner to regulate monocyte metabolism, histone methylation, and gene expression. Resting platelet-monocyte interactions limit TLR (toll-like receptor) signaling responses in healthy conditions in an innate immune training-like manner. In both human patients with sepsis and mouse sepsis models, thrombocytopenia exacerbated monocyte immune dysfunction, including increased cytokine production.

CONCLUSIONS

Thrombocytopenia immune programs monocytes in a manner that may lead to immune dysfunction in the context of sepsis. This is the first demonstration that sterile, endogenous cell interactions between resting platelets and monocytes regulate monocyte metabolism and pathogen responses, demonstrating platelets to be immune rheostats in both health and disease.

The causes and consequences of trained immunity in myeloid cells

Conventionally, immunity in humans has been classified as innate and adaptive, with the concept that only the latter type has an immunological memory/recall response against specific antigens or pathogens. Recently, a new concept of trained immunity (a.k.a. innate memory response) has emerged. According to this concept, innate immune cells can exhibit enhanced responsiveness to subsequent challenges, after initial stimulation with antigen/pathogen. Thus, trained immunity enables the innate immune cells to respond robustly and non-specifically through exposure or re-exposure to antigens/infections or vaccines, providing enhanced resistance to unrelated pathogens or reduced infection severity. For example, individuals vaccinated with BCG to protect against tuberculosis were also protected from malaria and SARS-CoV-2 infections. Epigenetic modifications such as histone acetylation and metabolic reprogramming (e.g. shift towards glycolysis) and their inter-linked regulations are the key factors underpinning the immune activation of trained cells. The integrated metabolic and epigenetic rewiring generates sufficient metabolic intermediates, which is crucial to meet the energy demand required to produce proinflammatory and antimicrobial responses by the trained cells. These factors also determine the efficacy and durability of trained immunity. Importantly, the signaling pathways and regulatory molecules of trained immunity can be harnessed as potential targets for developing novel intervention strategies, such as better vaccines and immunotherapies against infectious (e.g., sepsis) and non-infectious (e.g., cancer) diseases. However, aberrant inflammation caused by inappropriate onset of trained immunity can lead to severe autoimmune pathological consequences, (e.g., systemic sclerosis and granulomatosis). In this review, we provide an overview of conventional innate and adaptive immunity and summarize various mechanistic factors associated with the onset and regulation of trained immunity, focusing on immunologic, metabolic, and epigenetic changes in myeloid cells. This review underscores the transformative potential of trained immunity in immunology, paving the way for developing novel therapeutic strategies for various infectious and non-infectious diseases that leverage innate immune memory.

Multi-omics analysis reveals that linoleic acid metabolism is associated with variations of trained immunity induced by distinct BCG strains

Trained immunity is one of the mechanisms by which BCG vaccination confers persistent nonspecific protection against diverse diseases. Genomic differences between the different BCG vaccine strains that are in global use could result in variable protection against tuberculosis and therapeutic effects on bladder cancer. In this study, we found that four representative BCG strains (BCG-Russia, BCG-Sweden, BCG-China, and BCG-Pasteur) covering all four genetic clusters differed in their ability to induce trained immunity and nonspecific protection. The trained immunity induced by BCG was associated with the Akt-mTOR-HIF1α axis, glycolysis, and NOD-like receptor signaling pathway. Multi-omics analysis (epigenomics, transcriptomics, and metabolomics) showed that linoleic acid metabolism was correlated with the trained immunity-inducing capacity of different BCG strains. Linoleic acid participated in the induction of trained immunity and could act as adjuvants to enhance BCG-induced trained immunity, revealing a trained immunity-inducing signaling pathway that could be used in the adjuvant development.

Evolution of innate immunity: lessons from mammalian models shaping our current view of insect immunity

The innate immune system, a cornerstone for organismal resilience against environmental and microbial insults, is highly conserved across the evolutionary spectrum, underpinning its pivotal role in maintaining homeostasis and ensuring survival. This review explores the evolutionary parallels between mammalian and insect innate immune systems, illuminating how investigations into these disparate immune landscapes have been reciprocally enlightening. We further delve into how advancements in mammalian immunology have enriched our understanding of insect immune responses, highlighting the intertwined evolutionary narratives and the shared molecular lexicon of immunity across these organisms. Therefore, this review posits a holistic understanding of innate immune mechanisms, including immunometabolism, autophagy and cell death. The examination of how emerging insights into mammalian and vertebrate immunity inform our understanding of insect immune responses and their implications for vector-borne disease transmission showcases the imperative for a nuanced comprehension of innate immunity's evolutionary tale. This understanding is quintessential for harnessing innate immune mechanisms' potential in devising innovative disease mitigation strategies and promoting organismal health across the animal kingdom.

Tumor necrosis factor α-induced protein 8-like-2 controls microglia phenotype via metabolic reprogramming in BV2 microglial cells and responses to neuropathic pain

Microglial are major players in neuroinflammation that have recently emerged as potential therapeutic targets for neuropathic pain. Glucose metabolic programming has been linked to differential activation state and function in microglia. Tumor necrosis factor α-induced protein 8-like-2 (TNFAIP8L2) is an important component in regulating the anti-inflammatory response. However, the role of TNFAIP8L2 in microglia differential state during neuropathic pain and its interplay with glucose metabolic reprogramming in microglia has not yet been determined. Thus, we aimed to investigate the role of TNFAIP8L2 in the status of microglia in vitro and in vivo. BV2 microglial cells were treated with lipopolysaccharides plus interferon-gamma (LPS/IFNγ) or interleukin-4 (IL-4) to induce the two different phenotypes of microglia in vitro. In vivo experiments were conducted by chronic constriction injury of the sciatic nerve (CCI). We investigated whether TNFAIP8L2 regulates glucose metabolic programming in BV2 microglial cells. The data in vitro showed that TNFAIP8L2 lowers glycolysis and increases mitochondrial oxidative phosphorylation (OXPHOS) in inflammatory microglia. Blockade of glycolytic pathway abolished TNFAIP8L2-mediated differential activation of microglia. TNFAIP8L2 suppresses inflammatory microglial activation and promotes restorative microglial activation in BV2 microglial cells and in spinal cord microglia after neuropathic pain. Furthermore, TNFAIP8L2 controls differential activation of microglia and glucose metabolic reprogramming through the MAPK/mTOR/HIF-1α signaling axis. This study reveals that TNFAIP8L2 plays a critical role in neuropathic pain, providing important insights into glucose metabolic reprogramming and microglial phenotypic transition, which indicates that TNFAIP8L2 may be used as a potential drug target for the prevention of neuropathic pain.

Trained immunity-inducing vaccines: Harnessing innate memory for vaccine design and delivery

While the efficacy of many current vaccines is well-established, various factors can diminish their effectiveness, particularly in vulnerable groups. Amidst emerging pandemic threats, enhancing vaccine responses is critical. Our review synthesizes insights from immunology and epidemiology, focusing on the concept of trained immunity (TRIM) and the non-specific effects (NSEs) of vaccines that confer heterologous protection. We elucidate the mechanisms driving TRIM, emphasizing its regulation through metabolic and epigenetic reprogramming in innate immune cells. Notably, we explore the extended protective scope of vaccines like BCG and COVID-19 vaccines against unrelated infections, underscoring their role in reducing neonatal mortality and combating diseases like malaria and yellow fever. We also highlight novel strategies to boost vaccine efficacy, incorporating TRIM inducers into vaccine formulations to enhance both specific and non-specific immune responses. This approach promises significant advancements in vaccine development, aiming to improve global public health outcomes, especially for the elderly and immunocompromised populations.

Stress hyperglycaemia following trauma - a survival benefit or an outcome detriment?

PURPOSE OF REVIEW

Stress hyperglycaemia occur often in critically injured patients. To gain new consideration about it, this review compile current as well as known immunological and biochemical findings about causes and emergence.

RECENT FINDINGS

Glucose is the preferred energy substrate for fending immune cells, reparative tissue and the cardiovascular system following trauma. To fulfil these energy needs, the liver is metabolically reprogrammed to rebuild glucose from lactate and glucogenic amino acids (hepatic insulin resistance) at the expenses of muscles mass and - to a less extent - fat tissue (proteolysis, lipolysis, peripheral insulin resistance). This inevitably leads to stress hyperglycaemia, which is evolutionary preserved and seems to be an essential and beneficial survival response. It is initiated by damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs), intensified by immune cells itself and mainly ruled by tumour necrosis factor (TNF)α and catecholamines with lactate and hypoxia inducible factor (HIF)-1α as intracellular signals and lactate as an energy shuttle. Important biochemical mechanisms involved in this response are the Warburg effect as an efficient metabolic shortcut and the extended Cori cycle.

SUMMARY

Stress hyperglycaemia is beneficial in an acute life-threatening situation, but further research is necessary, to prevent trauma patients from the detrimental effects of persisting hyperglycaemia.

BCG as an Innovative Option for HCC Treatment: Repurposing and Mechanistic Insights

This study investigates Bacillus Calmette-Guérin (BCG) as a potential treatment for hepatocellular carcinoma (HCC), a condition often associated with unfavorable treatment outcomes. Exploiting BCG's recognized immune-boosting properties, preclinical trials are conducted using HCC mice, with a single subcutaneous dose of BCG administered post-tumor formation. Results indicate that BCG treatment effectively diminishes tumor burden and extends survival in both male and female HCC mice. Positive influences on hepatic fibrosis and metabolism are observed, leading to a reduction in lipid levels. Spatial analysis underscores BCG's tumor-specific effects, inducing the enrichment of metabolic pathways and inhibiting various cancer-related pathways. Furthermore, BCG promotes immune cell infiltration, including CD4+, CD8+ T cells, and M1 macrophages, in both v-akt murine thymoma viral oncogene homolog 1(AKT)/neutoblastoma RAS viral oncogene homolog (RAS) and β-catenin positive HCC models. Interestingly, blocking T cells, trained immunity, and Interferon-γ (IFN-γ) function reverses BCG's anti-HCC effects. In conclusion, BCG emerges as a promising treatment option for HCC, characterized by a favorable safety profile and efficacy in inhibiting fibrosis, improving metabolism, and engaging both trained immunity and T cells in therapeutic mechanisms.

The effects of primary and secondary bacterial exposure on the seahorse (Hippocampus erectus) immune response

Evolutionary adaptations in the Syngnathidae teleost family (seahorses, pipefish and seadragons) culminated in an array of spectacular morphologies, key immune gene losses, and the enigmatic male pregnancy. In seahorses, genome modifications associated with immunoglobulins, complement, and major histocompatibility complex (MHC II) pathway components raise questions concerning their immunological efficiency and the evolution of compensatory measures that may act in their place. In this investigation heat-killed bacteria (Vibrio aestuarianus and Tenacibaculum maritimum) were used in a two-phased experiment to assess the immune response dynamics of Hippocampus erectus. Gill transcriptomes from double and single-exposed individuals were analysed in order to determine the differentially expressed genes contributing to immune system responses towards immune priming. Double-exposed individuals exhibited a greater adaptive immune response when compared with single-exposed individuals, while single-exposed individuals, particularly with V. aestuarianus replicates, associated more with the innate branch of the immune system. T. maritimum double-exposed replicates exhibited the strongest immune reaction, likely due to their immunological naivety towards the bacterium, while there are also potential signs of innate trained immunity. MHC II upregulated expression was identified in selected V. aestuarianus-exposed seahorses, in the absence of other pathway constituents suggesting a possible alternative or non-classical MHC II immune function in seahorses. Gene Ontology (GO) enrichment analysis highlighted prominent angiogenesis activity following secondary exposure, which could be linked to an adaptive immune process in seahorses. This investigation highlights the prominent role of T-cell mediated adaptive immune responses in seahorses when exposed to sequential foreign bacteria exposures. If classical MHC II pathway function has been lost, innate trained immunity in syngnathids could be a potential compensatory mechanism.