Modification of Proteins by Metabolites in Immunity

Mycoplasma genitalium membrane lipoprotein induces GAPDH malonylation in urethral epithelial cells to regulate cytokine response

Membrane lipoproteins serve as primary pro-inflammatory virulence factors in Mycoplasma genitalium. Membrane lipoproteins primarily induce inflammatory responses by activating Toll-like Receptor 2 (TLR2); however, the role of the metabolic status of urethral epithelial cells in inflammatory response remains unclear. In this study, we found that treatment of uroepithelial cell lines with M. genitalium membrane lipoprotein induced metabolic reprogramming, characterized by increased aerobic glycolysis, decreased oxidative phosphorylation, and increased production of the metabolic intermediates acetyl-CoA and malonyl-CoA. The metabolic shift induced by membrane lipoproteins is reversible upon blocking MyD88 and TRAM. Malonyl-CoA induces malonylation of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and malonylated GAPDH could dissociate from the 3' untranslated region of TNF-α and IFN-γ mRNA. This dissociation greatly reduces the inhibitory effect on the translation of TNF-α and IFN-γ mRNA, thus achieving fine-tuning control over cytokine secretion. These findings suggest that GAPDH malonylation following M. genitalium infection is an important inflammatory signal that plays a crucial role in urogenital inflammatory diseases.

Inducible antibacterial responses in macrophages

Macrophages destroy bacteria and other microorganisms through phagocytosis-coupled antimicrobial responses, such as the generation of reactive oxygen species and the delivery of hydrolytic enzymes from lysosomes to the phagosome. However, many intracellular bacteria subvert these responses, escaping to other cellular compartments to survive and/or replicate. Such bacterial subversion strategies are countered by a range of additional direct antibacterial responses that are switched on by pattern-recognition receptors and/or host-derived cytokines and other factors, often through inducible gene expression and/or metabolic reprogramming. Our understanding of these inducible antibacterial defence strategies in macrophages is rapidly evolving. In this Review, we provide an overview of the broad repertoire of antibacterial responses that can be engaged in macrophages, including LC3-associated phagocytosis, metabolic reprogramming and antimicrobial metabolites, lipid droplets, guanylate-binding proteins, antimicrobial peptides, metal ion toxicity, nutrient depletion, autophagy and nitric oxide production. We also highlight key inducers, signalling pathways and transcription factors involved in driving these different antibacterial responses. Finally, we discuss how a detailed understanding of the molecular mechanisms of antibacterial responses in macrophages might be exploited for developing host-directed therapies to combat antibiotic-resistant bacterial infections.

Targeting SNRNP200-induced splicing dysregulation offers an immunotherapy opportunity for glycolytic triple-negative breast cancer

Metabolic dysregulation is prominent in triple-negative breast cancer (TNBC), yet therapeutic strategies targeting cancer metabolism are limited. Here, utilizing multiomics data from our TNBC cohort (n = 465), we demonstrated widespread splicing deregulation and increased spliceosome abundance in the glycolytic TNBC subtype. We identified SNRNP200 as a crucial mediator of glucose-driven metabolic reprogramming. Mechanistically, glucose induces acetylation at SNRNP200 K1610, preventing its proteasomal degradation. Augmented SNRNP200 then facilitates splicing key metabolic enzyme-encoding genes (GAPDH, ALDOA, and GSS), leading to increased lactic acid and glutathione production. Targeting SNRNP200 with antisense oligonucleotide therapy impedes tumor metabolism and enhances the efficacy of anti-PD-1 therapy by activating intratumoral CD8+ T cells while suppressing regulatory T cells. Clinically, higher SNRNP200 levels indicate an inferior response to immunotherapy in glycolytic TNBCs. Overall, our study revealed the intricate interplay between RNA splicing and metabolic dysregulation, suggesting an innovative combination strategy for immunotherapy in glycolytic TNBCs.

Role of novel protein acylation modifications in immunity and its related diseases

The cross-regulation of immunity and metabolism is currently a research hotspot in life sciences and immunology. Metabolic immunology plays an important role in cutting-edge fields such as metabolic regulatory mechanisms in immune cell development and function, and metabolic targets and immune-related disease pathways. Protein post-translational modification (PTM) is a key epigenetic mechanism that regulates various biological processes and highlights metabolite functions. Currently, more than 400 PTM types have been identified to affect the functions of several proteins. Among these, metabolic PTMs, particularly various newly identified histone or non-histone acylation modifications, can effectively regulate various functions, processes and diseases of the immune system, as well as immune-related diseases. Thus, drugs aimed at targeted acylation modification can have substantial therapeutic potential in regulating immunity, indicating a new direction for further clinical translational research. This review summarises the characteristics and functions of seven novel lysine acylation modifications, including succinylation, S-palmitoylation, lactylation, crotonylation, 2-hydroxyisobutyrylation, β-hydroxybutyrylation and malonylation, and their association with immunity, thereby providing valuable references for the diagnosis and treatment of immune disorders associated with new acylation modifications.

MOF-mediated PRDX1 acetylation regulates inflammatory macrophage activation

Signaling-dependent changes in protein phosphorylation are critical to enable coordination of transcription and metabolism during macrophage activation. However, the role of acetylation in signal transduction during macrophage activation remains obscure. Here, we identify the redox signaling regulator peroxiredoxin 1 (PRDX1) as a substrate of the lysine acetyltransferase MOF. MOF acetylates PRDX1 at lysine 197, preventing hyperoxidation and thus maintaining its activity under stress. PRDX1 K197ac responds to inflammatory signals, decreasing rapidly in mouse macrophages stimulated with bacterial lipopolysaccharides (LPSs) but not with interleukin (IL)-4 or IL-10. The LPS-induced decrease of PRDX1 K197ac elevates cellular hydrogen peroxide accumulation and augments ERK1/2, but not p38 or AKT, phosphorylation. Concomitantly, diminished PRDX1 K197ac stimulates glycolysis, potentiates H3 serine 28 phosphorylation, and ultimately enhances the production of pro-inflammatory mediators such as IL-6. Our work reveals a regulatory role for redox protein acetylation in signal transduction and coordinating metabolic and transcriptional programs during inflammatory macrophage activation.

SMAD4 promotes EMT in COPD airway remodeling induced by cigarette smoke through interaction with O-GlcNAc transferase

Cigarette smoke (CS) is a prevalent chemical indoor air contaminant known to be the primary cause of EMT during airway remodeling in COPD. While some evidence indicates the involvement of SMAD4 in EMT across certain diseases, its specific role in CS-induced EMT in airway remodeling associated with COPD is not established. In our research, we observed a substantial upregulation in SMAD4 expression, O-GlcNAcylation and EMT in patients with COPD, as well as in vitro and in vivo COPD models induced by CS, than those of the controls. Downregulation of SMAD4 resulted in a reduction in CS-induced EMT in vitro and in vivo. As a post-translational modification of proteins, O-GlcNAcylation is dynamically controlled by the duo of enzymes: O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) and O-GlcNAcase (OGA). We further discovered the enhancement of O-GlcNAcylation levels induced by CS was due to an elevated OGT expression, as the expression of OGA remained unchanged. Using an OGT inhibitor (OSMI-1) counteracted the effects of SMAD4 on EMT. Whereas, overexpressing OGT increased SMAD4 expression and promoted EMT. OGT-mediated SMAD4 O-GlcNAcylation shielded SMAD4 from proteasomal degradation by reducing its ubiquitination, thereby aiding in SMAD4 stabilization in response to EMT induced by CS. Overall, this research uncovers a fresh pathway for CS-induced EMT in the airway remodeling of COPD and offers valuable insights.

Tricarboxylic Acid Cycle Relationships with Non-Metabolic Processes: A Short Story with DNA Repair and Its Consequences on Cancer Therapy Resistance

Metabolic changes involving the tricarboxylic acid (TCA) cycle have been linked to different non-metabolic cell processes. Among them, apart from cancer and immunity, emerges the DNA damage response (DDR) and specifically DNA damage repair. The oncometabolites succinate, fumarate and 2-hydroxyglutarate (2HG) increase reactive oxygen species levels and create pseudohypoxia conditions that induce DNA damage and/or inhibit DNA repair. Additionally, by influencing DDR modulation, they establish direct relationships with DNA repair on at least four different pathways. The AlkB pathway deals with the removal of N-alkylation DNA and RNA damage that is inhibited by fumarate and 2HG. The MGMT pathway acts in the removal of O-alkylation DNA damage, and it is inhibited by the silencing of the MGMT gene promoter by 2HG and succinate. The other two pathways deal with the repair of double-strand breaks (DSBs) but with opposite effects: the FH pathway, which uses fumarate to help with the repair of this damage, and the chromatin remodeling pathway, in which oncometabolites inhibit its repair by impairing the homologous recombination repair (HRR) system. Since oncometabolites inhibit DNA repair, their removal from tumor cells will not always generate a positive response in cancer therapy. In fact, their presence contributes to longer survival and/or sensitization against tumor therapy in some cancer patients.

The Current Molecular and Cellular Landscape of Chronic Obstructive Pulmonary Disease (COPD): A Review of Therapies and Efforts towards Personalized Treatment

Chronic obstructive pulmonary disease (COPD) ranks as the third leading cause of global illness and mortality. It is commonly triggered by exposure to respiratory irritants like cigarette smoke or biofuel pollutants. This multifaceted condition manifests through an array of symptoms and lung irregularities, characterized by chronic inflammation and reduced lung function. Present therapies primarily rely on maintenance medications to alleviate symptoms, but fall short in impeding disease advancement. COPD's diverse nature, influenced by various phenotypes, complicates diagnosis, necessitating precise molecular characterization. Omics-driven methodologies, including biomarker identification and therapeutic target exploration, offer a promising avenue for addressing COPD's complexity. This analysis underscores the critical necessity of improving molecular profiling to deepen our comprehension of COPD and identify potential therapeutic targets. Moreover, it advocates for tailoring treatment strategies to individual phenotypes. Through comprehensive exploration-based molecular characterization and the adoption of personalized methodologies, innovative treatments may emerge that are capable of altering the trajectory of COPD, instilling optimism for efficacious disease-modifying interventions.

Microglia in Health and Diseases: Integrative Hubs of the Central Nervous System (CNS)

Microglia are usually referred to as "the innate immune cells of the brain," "the resident macrophages of the central nervous system" (CNS), or "CNS parenchymal macrophages." These labels allude to their inherent immune function, related to their macrophage lineage. However, beyond their classic innate immune responses, microglia also play physiological roles crucial for proper brain development and maintenance of adult brain homeostasis. Microglia sense both external and local stimuli through a variety of surface receptors. Thus, they might serve as integrative hubs at the interface between the external environment and the CNS, able to decode, filter, and buffer cues from outside, with the aim of preserving and maintaining brain homeostasis. In this perspective, we will cast a critical look at how these multiple microglial functions are acquired and coordinated, and we will speculate on their impact on human brain physiology and pathology.

UFMylation: An integral post-translational modification for the regulation of proteostasis and cellular functions

Ubiquitin-fold modifier 1 (UFM1) is covalently conjugated to protein substrates via a cascade of enzymatic reactions, a process known as UFMylation. UFMylation orchestrates an array of vital biological functions, including maintaining endoplasmic reticulum (ER) homeostasis, facilitating protein biogenesis, promoting cellular differentiation, regulating DNA damage response, and participating in cancer-associated signaling pathways. UFMylation has rapidly evolved into one of the forefront research areas within the last few years, yet much remains to be uncovered. In this review, first, UFMylation and its cellular functions associated with diseases are briefly introduced. Then, we summarize the proteomic approaches for identifying UFMylation substrates and explore the impact of UFMylation on gene transcription, protein translation, and maintenance of ER homeostasis. Next, we highlight the intricate regulation between UFMylation and two protein degradation pathways, the ubiquitin-proteasome system and the autophagy-lysosome pathway, and explore the potential of UFMylation system as a drug target. Finally, we discuss emerging perspectives in the UFMylation field. This review may provide valuable insights for drug discovery targeting the UFMylation system.

The glycolytic enzyme PFKFB3 drives kidney fibrosis through promoting histone lactylation-mediated NF-κB family activation

Persistently elevated glycolysis in kidney has been demonstrated to promote chronic kidney disease (CKD). However, the underlying mechanism remains largely unclear. Here, we observed that 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), a key glycolytic enzyme, was remarkably induced in kidney proximal tubular cells (PTCs) following ischemia-reperfusion injury (IRI) in mice, as well as in multiple etiologies of patients with CKD. PFKFB3 expression was positively correlated with the severity of kidney fibrosis. Moreover, patients with CKD and mice exhibited increased urinary lactate/creatine levels and kidney lactate, respectively. PTC-specific deletion of PFKFB3 significantly reduced kidney lactate levels, mitigated inflammation and fibrosis, and preserved kidney function in the IRI mouse model. Similar protective effects were observed in mice with heterozygous deficiency of PFKFB3 or those treated with a PFKFB3 inhibitor. Mechanistically, lactate derived from PFKFB3-mediated tubular glycolytic reprogramming markedly enhanced histone lactylation, particularly H4K12la, which was enriched at the promoter of NF-κB signaling genes like Ikbkb, Rela, and Relb, activating their transcription and facilitating the inflammatory response. Further, PTC-specific deletion of PFKFB3 inhibited the activation of IKKβ, I κ B α, and p65 in the IRI kidneys. Moreover, increased H4K12la levels were positively correlated with kidney inflammation and fibrosis in patients with CKD. These findings suggest that tubular PFKFB3 may play a dual role in enhancing NF-κB signaling by promoting both H4K12la-mediated gene transcription and its activation. Thus, targeting the PFKFB3-mediated NF-κB signaling pathway in kidney tubular cells could be a novel strategy for CKD therapy.

circSORBS1 inhibits lung cancer progression by sponging miR-6779-5p and directly binding RUFY3 mRNA

Lung cancer is the primary cause of cancer-related death worldwide, and its global incidence and mortality rates remain high. The differential expression of circular RNAs (circRNAs) can affect the development of cancer, but the mechanisms by which circRNAs regulate lung cancer progression remain unclear. In this study, we identified circSORBS1, a circRNA that has not been previously described in lung cancer and is significantly underexpressed in lung cancer tissues, blood and cell lines, and the low expression of circSORBS1 correlated with tumour grade and prognosis. In vitro and in vivo functional experiments revealed that circSORBS1 overexpression inhibited cell proliferation and migration while enhancing apoptosis. Mechanistically, circSORBS1 acts as a sponge for miR-6779-5p, indirectly inhibiting RUFY3 mRNA degradation. Simultaneously, it binds to RUFY3 mRNA to enhance its stability. This dual regulatory mechanism leads to an increase in RUFY3 protein levels, which ultimately activates the YWHAE/BAD/BCL2 apoptotic signalling pathway and suppresses lung cancer progression. Our findings not only increase the knowledge about the regulatory pattern of circRNA expression but also provide new insights into the mechanisms by which circRNAs regulate lung cancer development.

SUCLG1 restricts POLRMT succinylation to enhance mitochondrial biogenesis and leukemia progression

Mitochondria are cellular powerhouses that generate energy through the electron transport chain (ETC). The mitochondrial genome (mtDNA) encodes essential ETC proteins in a compartmentalized manner, however, the mechanism underlying metabolic regulation of mtDNA function remains unknown. Here, we report that expression of tricarboxylic acid cycle enzyme succinate-CoA ligase SUCLG1 strongly correlates with ETC genes across various TCGA cancer transcriptomes. Mechanistically, SUCLG1 restricts succinyl-CoA levels to suppress the succinylation of mitochondrial RNA polymerase (POLRMT). Lysine 622 succinylation disrupts the interaction of POLRMT with mtDNA and mitochondrial transcription factors. SUCLG1-mediated POLRMT hyposuccinylation maintains mtDNA transcription, mitochondrial biogenesis, and leukemia cell proliferation. Specifically, leukemia-promoting FMS-like tyrosine kinase 3 (FLT3) mutations modulate nuclear transcription and upregulate SUCLG1 expression to reduce succinyl-CoA and POLRMT succinylation, resulting in enhanced mitobiogenesis. In line, genetic depletion of POLRMT or SUCLG1 significantly delays disease progression in mouse and humanized leukemia models. Importantly, succinyl-CoA level and POLRMT succinylation are downregulated in FLT3-mutated clinical leukemia samples, linking enhanced mitobiogenesis to cancer progression. Together, SUCLG1 connects succinyl-CoA with POLRMT succinylation to modulate mitochondrial function and cancer development.

Increased Glycolytic Activity Is Part of Impeded M1(LPS) Macrophage Polarization in the Presence of Urolithin A

Urolithin A is a gut metabolite of ellagitannins and reported to confer health benefits, e.g., by increased clearance of damaged mitochondria by macroautophagy or curbed inflammation. One targeted cell type are macrophages, which are plastic and able to adopt pro- or anti-inflammatory polarization states, usually assigned as M1 and M2 macrophages, respectively. This flexibility is tightly coupled to characteristic shifts in metabolism, such as increased glycolysis in M1 macrophages, and protein expression upon appropriate stimulation. This study aimed at investigating whether the anti-inflammatory properties of U: rolithin A may be driven by metabolic alterations in cultivated murine M1(lipopolysaccharide) macrophages. Expression and extracellular flux analyses showed that urolithin A led to reduced il1β, il6, and nos2 expression and boosted glycolytic activity in M1(lipopolysaccharide) macrophages. The pro-glycolytic feature of UROLITHIN A: occurred in order to causally contribute to its anti-inflammatory potential, based on experiments in cells with impeded glycolysis. Mdivi, an inhibitor of mitochondrial fission, blunted increased glycolytic activity and reduced M1 marker expression in M1(lipopolysaccharide/UROLITHIN A: ), indicating that segregation of mitochondria was a prerequisite for both actions of UROLITHIN A: . Overall, we uncovered a so far unappreciated metabolic facet within the anti-inflammatory activity of UROLITHIN A: and call for caution about the simplified notion of increased aerobic glycolysis as an inevitably proinflammatory feature in macrophages upon exposure to natural products.

Interleukin-10 suppresses lipid metabolism-mediated intestinal inflammation

In a recent paper published in Nature, York et al. reported that the anti-inflammatory cytokine IL-10 regulates sphingolipid metabolism to limit NF-κB-mediated inflammation. Deletion of Il10 in mice, or genetic mutation of IL10 in humans, predisposes to inflammatory bowel disease, which may be overcome by restoring homeostatic sphingolipid metabolism.

Ovarian aging: energy metabolism of oocytes

In women who are getting older, the quantity and quality of their follicles or oocytes and decline. This is characterized by decreased ovarian reserve function (DOR), fewer remaining oocytes, and lower quality oocytes. As more women choose to delay childbirth, the decline in fertility associated with age has become a significant concern for modern women. The decline in oocyte quality is a key indicator of ovarian aging. Many studies suggest that age-related changes in oocyte energy metabolism may impact oocyte quality. Changes in oocyte energy metabolism affect adenosine 5'-triphosphate (ATP) production, but how related products and proteins influence oocyte quality remains largely unknown. This review focuses on oocyte metabolism in age-related ovarian aging and its potential impact on oocyte quality, as well as therapeutic strategies that may partially influence oocyte metabolism. This research aims to enhance our understanding of age-related changes in oocyte energy metabolism, and the identification of biomarkers and treatment methods.

Discrepant Phenotyping of Monocytes Based on CX3CR1 and CCR2 Using Fluorescent Reporters and Antibodies

Monocytes, as well as downstream macrophages and dendritic cells, are essential players in the immune system, fulfilling key roles in homeostasis as well as in inflammatory conditions. Conventionally, driven by studies on reporter models, mouse monocytes are categorized into a classical and a non-classical subset based on their inversely correlated surface expression of Ly6C/CCR2 and CX3CR1. Here, we aimed to challenge this concept by antibody staining and reporter mouse models. Therefore, we took advantage of Cx3cr1GFP and Ccr2RFP reporter mice, in which the respective gene was replaced by a fluorescent reporter protein gene. We analyzed the expression of CX3CR1 and CCR2 by flow cytometry using several validated fluorochrome-coupled antibodies and compared them with the reporter gene signal in these reporter mouse strains. Although we were able to validate the specificity of the fluorochrome-coupled flow cytometry antibodies, mouse Ly6Chigh classical and Ly6Clow non-classical monocytes showed no differences in CX3CR1 expression levels in the peripheral blood and spleen when stained with these antibodies. On the contrary, in Cx3cr1GFP reporter mice, we were able to reproduce the inverse correlation of the CX3CR1 reporter gene signal and Ly6C surface expression. Furthermore, differential CCR2 surface expression correlating with the expression of Ly6C was observed by antibody staining, but not in Ccr2RFP reporter mice. In conclusion, our data suggest that phenotyping strategies for mouse monocyte subsets should be carefully selected. In accordance with the literature, the suitability of CX3CR1 antibody staining is limited, whereas for CCR2, caution should be applied when using reporter mice.

Metabolic vulnerability of cancer stem cells and their niche

Cancer stem cells (CSC) are the leading cause of the failure of anti-tumor treatments. These aggressive cancer cells are preserved and sustained by adjacent cells forming a specialized microenvironment, termed niche, among which tumor-associated macrophages (TAMs) are critical players. The cycle of tricarboxylic acids, fatty acid oxidation path, and electron transport chain have been proven to play central roles in the development and maintenance of CSCs and TAMs. By improving their oxidative metabolism, cancer cells are able to extract more energy from nutrients, which allows them to survive in nutritionally defective environments. Because mitochondria are crucial bioenergetic hubs and sites of these metabolic pathways, major hopes are posed for drugs targeting mitochondria. A wide range of medications targeting mitochondria, electron transport chain complexes, or oxidative enzymes are currently investigated in phase 1 and phase 2 clinical trials against hard-to-treat tumors. This review article aims to highlight recent literature on the metabolic adaptations of CSCs and their supporting macrophages. A focus is provided on the resistance and dormancy behaviors that give CSCs a selection advantage and quiescence capacity in particularly hostile microenvironments and the role of TAMs in supporting these attitudes. The article also describes medicaments that have demonstrated a robust ability to disrupt core oxidative metabolism in preclinical cancer studies and are currently being tested in clinical trials.

The cancer-immune dialogue in the context of stress

Although there is little direct evidence supporting that stress affects cancer incidence, it does influence the evolution, dissemination and therapeutic outcomes of neoplasia, as shown in human epidemiological analyses and mouse models. The experience of and response to physiological and psychological stressors can trigger neurological and endocrine alterations, which subsequently influence malignant (stem) cells, stromal cells and immune cells in the tumour microenvironment, as well as systemic factors in the tumour macroenvironment. Importantly, stress-induced neuroendocrine changes that can regulate immune responses have been gradually uncovered. Numerous stress-associated immunomodulatory molecules (SAIMs) can reshape natural or therapy-induced antitumour responses by engaging their corresponding receptors on immune cells. Moreover, stress can cause systemic or local metabolic reprogramming and change the composition of the gastrointestinal microbiota which can indirectly modulate antitumour immunity. Here, we explore the complex circuitries that link stress to perturbations in the cancer-immune dialogue and their implications for therapeutic approaches to cancer.

Quantitative proteome and lysine succinylome characterization of zinc chloride smoke-induced lung injury in mice

The inhalation of zinc chloride (ZnCl2) smoke is one of common resources of lung injury, potentially resulting in severe pulmonary complications and even mortality. The influence of ZnCl2 smoke on lysine succinylation (Ksucc) in the lungs remains uncertain. In this study, we used a ZnCl2 smoke inhalation mouse model to perform global proteomic and lysine succinylome analyses. A total of 6781 Ksucc sites were identified in the lungs, with injured lungs demonstrating a reduction to approximately 2000 Ksucc sites, and 91 proteins exhibiting at least five differences in the number of Ksucc sites. Quantitative analysis revealed variations in expression of 384 proteins and 749 Ksucc sites. The analysis of protein-protein interactions was conducted for proteins displaying differential expression and differentially expressed lysine succinylation. Notably, proteins with altered Ksucc exhibited increased connectivity compared with that in differentially expressed proteins. Beyond metabolic pathways, these highly connected proteins were also involved in lung injury-associated pathological reactions, including processes such as focal adhesion, adherens junction, and complement and coagulation cascades. Collectively, our findings contribute to the understanding of the molecular mechanisms underlaying ZnCl2 smoke-induced lung injury with a specific emphasis on lysine succinylation. These findings could pave the way for targeted interventions and therapeutic strategies to mitigate severe pulmonary complications and mortality associated with such injuries in humans.

New insights into the role of immunity and inflammation in diabetic kidney disease in the omics era

Diabetic kidney disease (DKD) is becoming the leading cause of chronic kidney disease, especially in the industrialized world. Despite mounting evidence has demonstrated that immunity and inflammation are highly involved in the pathogenesis and progression of DKD, the underlying mechanisms remain incompletely understood. Substantial molecules, signaling pathways, and cell types participate in DKD inflammation, by integrating into a complex regulatory network. Most of the studies have focused on individual components, without presenting their importance in the global or system-based processes, which largely hinders clinical translation. Besides, conventional technologies failed to monitor the different behaviors of resident renal cells and immune cells, making it difficult to understand their contributions to inflammation in DKD. Recently, the advancement of omics technologies including genomics, epigenomics, transcriptomics, proteomics, and metabolomics has revolutionized biomedical research, which allows an unbiased global analysis of changes in DNA, RNA, proteins, and metabolites in disease settings, even at single-cell and spatial resolutions. They help us to identify critical regulators of inflammation processes and provide an overview of cell heterogeneity in DKD. This review aims to summarize the application of multiple omics in the field of DKD and emphasize the latest evidence on the interplay of inflammation and DKD revealed by these technologies, which will provide new insights into the role of inflammation in the pathogenesis of DKD and lead to the development of novel therapeutic approaches and diagnostic biomarkers.

Control of immune cell signaling by the immuno-metabolite itaconate

Immune cell activation triggers signaling cascades leading to transcriptional reprogramming, but also strongly impacts on the cell's metabolic activity to provide energy and biomolecules for inflammatory and proliferative responses. Macrophages activated by microbial pathogen-associated molecular patterns and cytokines upregulate expression of the enzyme ACOD1 that generates the immune-metabolite itaconate by decarboxylation of the TCA cycle metabolite cis-aconitate. Itaconate has anti-microbial as well as immunomodulatory activities, which makes it attractive as endogenous effector metabolite fighting infection and restraining inflammation. Here, we first summarize the pathways and stimuli inducing ACOD1 expression in macrophages. The focus of the review then lies on the mechanisms by which itaconate, and its synthetic derivatives and endogenous isomers, modulate immune cell signaling and metabolic pathways. Multiple targets have been revealed, from inhibition of enzymes to the post-translational modification of many proteins at cysteine or lysine residues. The modulation of signaling proteins like STING, SYK, JAK1, RIPK3 and KEAP1, transcription regulators (e.g. Tet2, TFEB) and inflammasome components (NLRP3, GSDMD) provides a biochemical basis for the immune-regulatory effects of the ACOD1-itaconate pathway. While the field has intensely studied control of macrophages by itaconate in infection and inflammation models, neutrophils have now entered the scene as producers and cellular targets of itaconate. Furthermore, regulation of adaptive immune responses by endogenous itaconate, as well as by exogenously added itaconate and derivatives, can be mediated by direct and indirect effects on T cells and antigen-presenting cells, respectively. Taken together, research in ACOD1-itaconate to date has revealed its relevance in diverse immune cell signaling pathways, which now provides opportunities for potential therapeutic or preventive manipulation of host defense and inflammation.

Mitochondria: the gatekeepers between metabolism and immunity

Metabolism and immunity are crucial monitors of the whole-body homeodynamics. All cells require energy to perform their basic functions. One of the most important metabolic skills of the cell is the ability to optimally adapt metabolism according to demand or availability, known as metabolic flexibility. The immune cells, first line of host defense that circulate in the body and migrate between tissues, need to function also in environments in which nutrients are not always available. The resilience of immune cells consists precisely in their high adaptive capacity, a challenge that arises especially in the framework of sustained immune responses. Pubmed and Scopus databases were consulted to construct the extensive background explored in this review, from the Kennedy and Lehninger studies on mitochondrial biochemistry of the 1950s to the most recent findings on immunometabolism. In detail, we first focus on how metabolic reconfiguration influences the action steps of the immune system and modulates immune cell fate and function. Then, we highlighted the evidence for considering mitochondria, besides conventional cellular energy suppliers, as the powerhouses of immunometabolism. Finally, we explored the main immunometabolic hubs in the organism emphasizing in them the reciprocal impact between metabolic and immune components in both physiological and pathological conditions.

Potential for New Therapeutic Approaches by Targeting Lactate and pH Mediated Epigenetic Dysregulation in Major Mental Diseases

Multiple lines of evidence have shown that lactate-mediated pH alterations in the brains of patients with neuropsychiatric diseases such as schizophrenia (SCZ), Alzheimer's disease (AD) and autism may be attributed to mitochondrial dysfunction and changes in energy metabolism. While neuronal activity is associated with reduction in brain pH, astrocytes are responsible for rebalancing the pH to maintain the equilibrium. As lactate level is the main determinant of brain pH, neuronal activities are impacted by pH changes due to the binding of protons (H+) to various types of proteins, altering their structure and function in the neuronal and non-neuronal cells of the brain. Lactate and pH could affect diverse types of epigenetic modifications, including histone lactylation, which is linked to histone acetylation and DNA methylation. In this review, we discuss the importance of pH homeostasis in normal brain function, the role of lactate as an essential epigenetic regulatory molecule and its contributions to brain pH abnormalities in neuropsychiatric diseases, and shed light on lactate-based and pH-modulating therapies in neuropsychiatric diseases by targeting epigenetic modifications. In conclusion, we attempt to highlight the potentials and challenges of translating lactate-pH-modulating therapies to clinics for the treatment of neuropsychiatric diseases.

Serine synthesis sustains macrophage IL-1β production via NAD+-dependent protein acetylation

Serine metabolism is involved in the fate decisions of immune cells; however, whether and how de novo serine synthesis shapes innate immune cell function remain unknown. Here, we first demonstrated that inflammatory macrophages have high expression of phosphoglycerate dehydrogenase (PHGDH, the rate-limiting enzyme of de novo serine synthesis) via nuclear factor κB signaling. Notably, the pharmacological inhibition or genetic modulation of PHGDH limits macrophage interleukin (IL)-1β production through NAD+ accumulation and subsequent NAD+-dependent SIRT1 and SIRT3 expression and activity. Mechanistically, PHGDH not only sustains IL-1β expression through H3K9/27 acetylation-mediated transcriptional activation of Toll-like receptor 4 but also supports IL-1β maturation via NLRP3-K21/22/24/ASC-K21/22/24 acetylation-mediated activation of the NLRP3 inflammasome. Moreover, mice with myeloid-specific depletion of Phgdh show alleviated inflammatory responses in lipopolysaccharide-induced systemic inflammation. This study reveals a network by which a metabolic enzyme, involved in de novo serine synthesis, mediates post-translational modifications and epigenetic regulation to orchestrate IL-1β production, providing a potential inflammatory disease target.

C-Terminal Binding Protein 2 Emerges as a Critical Player Linking Metabolic Imbalance to the Pathogenesis of Obesity

Metabolism is one of the vital functions of cells and living organisms, and the systems to sense and respond to the metabolic alterations play pivotal roles in a plethora of biological processes, including cell proliferative activities, immune cell functions, aging processes, and neuronal functions. Recently, we have reported that a transcriptional cofactor, C-terminal binding protein 2 (CtBP2), serves as a critical metabolite sensor in this context. CtBP2 has a structural pocket called Rossmann fold to accommodate metabolites, and it has been reported to be activated upon binding to NADH/NAD＋. Owing to its preferential binding affinity for NADH compared with NAD＋, increased glycolysis activates CtBP2 by regenerating NADH from NAD＋. Furthermore, we recently reported that fatty acyl-CoAs, metabolites accumulated under the condition of lipid overload, as represented by obesity, can inactivate CtBP2. These observations suggest that CtBP2 monitors not only redox state but also energy substrate preference in the maintenance of metabolic homeostasis. In line with these metabolite-sensing capabilities, CtBP2 is activated in healthy subjects to protect against metabolic disturbances, whereas inactivation of CtBP2 in obesity contributes to the pathogeneses of obesity.This metabolic system orchestrated by CtBP2 can provide a novel framework for understanding how cells maintain their homeostasis through coordination of metabolism, and CtBP2 incapacitation can be a critical point of the obesogenic cascade.

The mitochondrial thiolase ACAT1 regulates monocyte/macrophage type I interferon via epigenetic control

Lipid-derived acetyl-CoA is shown to be the major carbon source for histone acetylation. However, there is no direct evidence demonstrating lipid metabolic pathway contribututions to this process. Mitochondrial acetyl-CoA acetyltransferase 1 (ACAT1) catalyzes the final step of ß-oxidation, the aerobic process catabolizing fatty acids (FA) into acetyl-CoA. To investigate this in the context of immunometabolism, we generated macrophage cell line lacking ACAT1. 13C-carbon tracing combined with mass spectrometry confirmed incorporation of FA-derived carbons into histone H3 and this incorporation was reduced in ACAT1 KO macrophage cells. RNA-seq identified a subset of genes downregulated in ACAT1 KO cells including STAT1/2 and interferon stimulated genes (ISGs). CHIP analysis demonstrated reduced acetyl-H3 binding to STAT1 promoter/enhancer regions. Increasing histone acetylation rescued STAT1/2 expression in ACAT1 KO cells. Concomitantly, ligand triggered IFNβ release was blunted in ACAT1 KO cells and rescued by reconstitution of ACAT1. Furthermore, ACAT1 promotes FA-mediated histone acetylation in an acetylcarnitine shuttle-dependent manner. In patients with obesity, levels of ACAT1 and histone acetylation are abnormally elevated. Thus, our study identified a novel link between ACAT1 mediated FA metabolism and epigenetic modification on STAT1/2 that uncovers a regulatory role of lipid metabolism in innate immune signaling and opens novel avenues for interventions in human diseases such as obesity.

ROS: Executioner of regulating cell death in spinal cord injury

The damage to the central nervous system and dysfunction of the body caused by spinal cord injury (SCI) are extremely severe. The pathological process of SCI is accompanied by inflammation and injury to nerve cells. Current evidence suggests that oxidative stress, resulting from an increase in the production of reactive oxygen species (ROS) and an imbalance in its clearance, plays a significant role in the secondary damage during SCI. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial regulatory molecule for cellular redox. This review summarizes recent advancements in the regulation of ROS-Nrf2 signaling and focuses on the interaction between ROS and the regulation of different modes of neuronal cell death after SCI, such as apoptosis, autophagy, pyroptosis, and ferroptosis. Furthermore, we highlight the pathways through which materials science, including exosomes, hydrogels, and nanomaterials, can alleviate SCI by modulating ROS production and clearance. This review provides valuable insights and directions for reducing neuronal cell death and alleviating SCI through the regulation of ROS and oxidative stress.

Immunomodulation in diabetic wounds healing: The intersection of macrophage reprogramming and immunotherapeutic hydrogels

Diabetic wound healing presents a significant clinical challenge due to the interplay of systemic metabolic disturbances and local inflammation, which hinder the healing process. Macrophages undergo a phenotypic shift from M1 to M2 during wound healing, a transition pivotal for effective tissue repair. However, in diabetic wounds, the microenvironment disrupts this phenotypic polarization, perpetuating inflammation, and impeding healing. Reprograming macrophages to restore their M2 phenotype offers a potential avenue for modulating the wound immune microenvironment and promoting healing. This review elucidates the mechanisms underlying impaired macrophage polarization toward the M2 phenotype in diabetic wounds and discusses novel strategies, including epigenetic and metabolic interventions, to promote macrophage conversion to M2. Hydrogels, with their hydrated 3D cross-linked structure, closely resemble the physiological extracellular matrix and offer advantageous properties such as biocompatibility, tunability, and versatility. These characteristics make hydrogels promising candidates for developing immunomodulatory materials aimed at addressing diabetic wounds. Understanding the role of hydrogels in immunotherapy, particularly in the context of macrophage reprograming, is essential for the development of advanced wound care solutions. This review also highlights recent advancements in immunotherapeutic hydrogels as a step toward precise and effective treatments for diabetic wounds.

Serine metabolism in macrophage polarization

OBJECTIVE

Emerging studies have revealed that macrophages possess different dependences on the uptake, synthesis, and metabolism of serine for their activation and functionalization, necessitating our insight into how serine availability and utilization impact macrophage activation and inflammatory responses.

METHODS

This article summarizes the reports published domestically and internationally about the serine uptake, synthesis, and metabolic flux by the macrophages polarizing with distinct stimuli and under different pathologic conditions, and particularly analyzes how altered serine metabolism rewires the metabolic behaviors of polarizing macrophages and their genetic and epigenetic reprogramming.

RESULTS

Macrophages dynamically change serine metabolism to orchestrate their anabolism, redox balance, mitochondrial function, epigenetics, and post-translation modification, and thus match the distinct needs for both classical and alternative activation.

CONCLUSION

Serine metabolism coordinates multiple metabolic pathways to tailor macrophage polarization and their responses to different pathogenic attacks and thus holds the potential as therapeutic target for types of acute and chronic inflammatory diseases.

T-cell senescence induced by peripheral phospholipids

We present an integrated analysis of the clinical measurements, immune cells, and plasma lipidomics of 2000 individuals representing different age stages. In the study, we explore the interplay of systemic lipids metabolism and circulating immune cells through in-depth analysis of immune cell phenotype and function in peripheral dynamic lipids environment. The population makeup of circulation lymphocytes and lipid metabolites changes dynamically with age. We identified a major shift between young group and middle age group, at which point elevated, immune response is accompanied by the elevation of specific classes of peripheral phospholipids. We tested the effects in mouse model and found that 10-month-dietary added phospholipids induced T-cell senescence. However, the chronic malignant disease, the crosstalk between systemic metabolism and immunity, is completely changed. In cancer patients, the unusual plasma cholesteryl esters emerged, and free fatty acids decreased. The study reveals how immune cell classes and peripheral metabolism coordinate during age acceleration and suggests immune senescence is not isolated, and thus, system effect is the critical point for cell- and function-specific immune-metabolic targeting. • The study identifies a major shift of immune phenotype between young group and middle age group, and the immune response is accompanied by the elevation of specific classes of peripheral phospholipids; • The study suggests potential implications for translational studies such as using metabolic drug to regulate immune activity.

Small molecule modulators of immune pattern recognition receptors

Pattern recognition receptors (PRRs) represent a re-emerging class of therapeutic targets for vaccine adjuvants, inflammatory diseases and cancer. In this review article, we summarize exciting developments in discovery and characterization of small molecule PRR modulators, focusing on Toll-like receptors (TLRs), NOD-like receptors (NLRs) and the cGAS-STING pathway. We also highlight PRRs that are currently lacking small molecule modulators and opportunities for chemical biology and therapeutic discovery.

A comprehensive analysis of SLC25A1 expression and its oncogenic role in pan-cancer

OBJECTIVE

The solute carrier family 25 member 1 (SLC25A1) is currently the only known human transporter for citrate in the mitochondrial membrane. However, its role in cancer development remains to be elucidated. We aim to analyze the expression profile, prognostic value, potential immunological significance, and effect on tumor growth of SLC25A1 at a pan-cancer level.

METHODS

Herein, the role of SLC25A1 in tumorigenesis and progression was investigated based on the Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), Genotype-Tissue Expression (GTEx), Clinical Proteomic Tumor Analysis Consortium (CPTAC), GeneMANIA, STRING and Cancer Dependency Map Project (DepMap) database via online websites or the R software. The protein expression levels were validated in tissue microarrays, and the effects on tumor cell lines were accessed through MTS and colony formation assays.

RESULTS

The expression of SLC25A1 increased in most cancers, and the upregulation of SLC25A1 in colon adenocarcinoma and lung adenocarcinoma was further confirmed by immunohistochemistry. Meanwhile, SLC25A1 was linked to clinical outcomes across multiple tumor types, particularly in lung adenocarcinoma, where its high expression predicted poor prognosis. Moreover, SLC25A1 was positively associated with MSI, TMB, and CD276 and tightly correlated with tumor-infiltrating immune cells. Furthermore, the knockout of SLC25A1 demonstrated inhibitory effects in most cancer cell lines in the DepMap project. Cellular experiments showed that SLC25A1 knockdown significantly reduced the proliferation of lung adenocarcinoma cells.

CONCLUSIONS

Our findings suggest the potential of SLC25A1 as a prognostic biomarker for cancers and a therapeutic target for precise antitumor strategy and cancer immunotherapy.

Exercise improves cognitive dysfunction and neuroinflammation in mice through Histone H3 lactylation in microglia

BACKGROUND

Exercise is postulated to be a promising non-pharmacological intervention for the improvement of neurodegenerative disease pathology. However, the mechanism of beneficial effects of exercise on the brain remains to be further explored. In this study, we investigated the effect of an exercise-induced metabolite, lactate, on the microglia phenotype and its association with learning and memory.

RESULTS

Microglia were hyperactivated in the brains of AlCl3/D-gal-treated mice, which was associated with cognitive decline. Running exercise ameliorated the hyperactivation and increased the anti-inflammatory/reparative phenotype of microglia and improved cognition. Mice were injected intraperitoneally with sodium lactate (NaLA) had similar beneficial effects as that of exercise training. Exogenous NaLA addition to cultured BV2 cells promoted their transition from a pro-inflammatory to a reparative phenotype.

CONCLUSION

The elevated lactate acted as an "accelerator" of the endogenous "lactate timer" in microglia promoting this transition of microglia polarization balance through lactylation. These findings demonstrate that exercise-induced lactate accelerates the phenotypic transition of microglia, which plays a key role in reducing neuroinflammation and improving cognitive function.

Amino acid metabolism reprogramming: shedding new light on T cell anti-tumor immunity

Metabolic reprogramming of amino acids has been increasingly recognized to initiate and fuel tumorigenesis and survival. Therefore, there is emerging interest in the application of amino acid metabolic strategies in antitumor therapy. Tremendous efforts have been made to develop amino acid metabolic node interventions such as amino acid antagonists and targeting amino acid transporters, key enzymes of amino acid metabolism, and common downstream pathways of amino acid metabolism. In addition to playing an essential role in sustaining tumor growth, new technologies and studies has revealed amino acid metabolic reprograming to have wide implications in the regulation of antitumor immune responses. Specifically, extensive crosstalk between amino acid metabolism and T cell immunity has been reported. Tumor cells can inhibit T cell immunity by depleting amino acids in the microenvironment through nutrient competition, and toxic metabolites of amino acids can also inhibit T cell function. In addition, amino acids can interfere with T cells by regulating glucose and lipid metabolism. This crucial crosstalk inspires the exploitation of novel strategies of immunotherapy enhancement and combination, owing to the unprecedented benefits of immunotherapy and the limited population it can benefit. Herein, we review recent findings related to the crosstalk between amino acid metabolism and T cell immunity. We also describe possible approaches to intervene in amino acid metabolic pathways by targeting various signaling nodes. Novel efforts to combine with and unleash potential immunotherapy are also discussed. Hopefully, some strategies that take the lead in the pipeline may soon be used for the common good.

The liver microenvironment orchestrates FGL1-mediated immune escape and progression of metastatic colorectal cancer

Colorectal cancer (CRC) patients with liver metastases usually obtain less benefit from immunotherapy, and the underlying mechanisms remain understudied. Here, we identify that fibrinogen-like protein 1 (FGL1), secreted from cancer cells and hepatocytes, facilitates the progression of CRC in an intraportal injection model by reducing the infiltration of T cells. Mechanistically, tumor-associated macrophages (TAMs) activate NF-ĸB by secreting TNFα/IL-1β in the liver microenvironment and transcriptionally upregulate OTU deubiquitinase 1 (OTUD1) expression, which enhances FGL1 stability via deubiquitination. Disrupting the TAM-OTUD1-FGL1 axis inhibits metastatic tumor progression and synergizes with immune checkpoint blockade (ICB) therapy. Clinically, high plasma FGL1 levels predict poor outcomes and reduced ICB therapy benefits. Benzethonium chloride, an FDA-approved antiseptics, curbs FGL1 secretion, thereby inhibiting liver metastatic tumor growth. Overall, this study uncovers the critical roles and posttranslational regulatory mechanism of FGL1 in promoting metastatic tumor progression, highlighting the TAM-OTUD1-FGL1 axis as a potential target for cancer immunotherapy.

Tissue-specific macrophage immunometabolism

Macrophages are phagocytic cells distributed across tissues that sustain homeostasis by constantly probing their local environment. Upon perturbations, macrophages rewire their energy metabolism to execute their immune programs. Intensive research in the field of immunometabolism highlights cell-intrinsic immunometabolites such as succinate and itaconate as immunomodulatory signals. A role for cell-extrinsic stimuli now emerges with evidence for signals that shape macrophages' metabolism in a tissue-specific manner. In this review, we will cover macrophage immunometabolism in the gut, a complex metabolic and immunologically active tissue. During homeostasis, gut macrophages are constantly exposed to pro-inflammatory ligands from the microbiota, and in contrast, are balanced by microbiota-derived anti-inflammatory metabolites. Given their extensive metabolic changes during activation, spatial analyses of the tissue will allow the characterization of metabolic niches of macrophage in the gut. Identifying metabolic perturbations of macrophage subsets during chronic inflammation and infection can direct future tissue-specific metabolotherapies.

S-palmitoylation regulates innate immune signaling pathways: molecular mechanisms and targeted therapies

S-palmitoylation is a reversible posttranslational lipid modification that targets cysteine residues of proteins and plays critical roles in regulating the biological processes of substrate proteins. The innate immune system serves as the first line of defense against pathogenic invaders and participates in the maintenance of tissue homeostasis. Emerging studies have uncovered the functions of S-palmitoylation in modulating innate immune responses. In this review, we focus on the reversible palmitoylation of innate immune signaling proteins, with particular emphasis on its roles in the regulation of protein localization, protein stability, and protein-protein interactions. We also highlight the potential and challenge of developing therapies that target S-palmitoylation or de-palmitoylation for various diseases.

Proteomics profiling and lysine malonylation analysis in primary Sjogren's syndrome

Primary Sjogren's Syndrome (pSS) is a chronic autoimmune disease, with unclear pathogenies. Lysine-malonylation (Kmal) as a novel post-translational modification (PTMs) was found associated with metabolic, immune, and inflammatory processes. For purpose of investigating the proteomic profile and functions of kmal in pSS, liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based analysis and bioinformatics analysis are performed based on twenty-eight pSS patients versus twenty-seven healthy controls (HCs). A total of 331 down-regulated proteins and 289 up-regulated proteins are observed in differentially expressed proteins (DEPs) of pSS. We discover the expression of transforming growth factor beta-1 (TGFB1) and CD40 ligand downregulate which enriches in the inflammatory associated pathway. Expression of signal transducer and activator of transcription 1-alpha/beta (STAT1) show upregulation and enrich in type I interferon signaling pathway and IL-27-mediated signaling pathway. In differentially malonylated proteins (DMPs) of pSS, we identify 3 proteins are down-regulated in 7 sites and 18 proteins are up-regulated in 19 sites. Expression of malonylated integrin-linked kinase (ILK) significantly enrich in the focal adhesion pathway. Together, our data provide evidence that downregulation of TGFB1 and CD40LG play a critical role in the inflammatory process of pSS, while upregulation of STAT1 may be associated with IL-27 immunity and pSS immune dysfunction. Moreover, kmal modification at the kinase domain of ILK may destabilize ILK that thus contributing to pSS pathogenies by regulating the focal adhesion pathway. SIGNIFICANCE: Our research offered the first characterization of Kmal, a newly identified form of lysine acylation in pSS, as well as proteomic data on individuals with pSS. In this study, we found that several key DMPs were associated with focal adhesion pathway, which contributes to the development of pSS. The present results provide an informative dataset for the future exploration of Kmal in pSS.

'Spikeopathy': COVID-19 Spike Protein Is Pathogenic, from Both Virus and Vaccine mRNA

The COVID-19 pandemic caused much illness, many deaths, and profound disruption to society. The production of 'safe and effective' vaccines was a key public health target. Sadly, unprecedented high rates of adverse events have overshadowed the benefits. This two-part narrative review presents evidence for the widespread harms of novel product COVID-19 mRNA and adenovectorDNA vaccines and is novel in attempting to provide a thorough overview of harms arising from the new technology in vaccines that relied on human cells producing a foreign antigen that has evidence of pathogenicity. This first paper explores peer-reviewed data counter to the 'safe and effective' narrative attached to these new technologies. Spike protein pathogenicity, termed 'spikeopathy', whether from the SARS-CoV-2 virus or produced by vaccine gene codes, akin to a 'synthetic virus', is increasingly understood in terms of molecular biology and pathophysiology. Pharmacokinetic transfection through body tissues distant from the injection site by lipid-nanoparticles or viral-vector carriers means that 'spikeopathy' can affect many organs. The inflammatory properties of the nanoparticles used to ferry mRNA; N1-methylpseudouridine employed to prolong synthetic mRNA function; the widespread biodistribution of the mRNA and DNA codes and translated spike proteins, and autoimmunity via human production of foreign proteins, contribute to harmful effects. This paper reviews autoimmune, cardiovascular, neurological, potential oncological effects, and autopsy evidence for spikeopathy. With many gene-based therapeutic technologies planned, a re-evaluation is necessary and timely.

The Dual Role of ACOD1 in Inflammation

Immunometabolism is an interdisciplinary field that focuses on the relationship between metabolic pathways and immune responses. Dysregulated immunometabolism contributes to many pathological settings, such as cytokine storm or immune tolerance. Aconitate decarboxylase 1 (ACOD1, also known as immunoresponsive gene 1), the mitochondrial enzyme responsible for catalyzing itaconate production, was originally identified as a bacterial LPS-inducible gene involved in innate immunity in mouse macrophages. We now know that the upregulation of ACOD1 expression in immune or nonimmune cells plays a context-dependent role in metabolic reprogramming, signal transduction, inflammasome regulation, and protein modification. The emerging function of ACOD1 in inflammation and infection is a double-edged sword. In this review, we discuss how ACOD1 regulates anti-inflammatory or proinflammatory responses in an itaconate-dependent or -independent manner. Further understanding of ACOD1 expression and function may pave the way for the development of precision therapies for inflammatory diseases.

Recovery of intracellular glucose uptake in T cells during partial remission of type 1 diabetes

AIMS/HYPOTHESIS

Notwithstanding the irreversible beta cell failure seen in type 1 diabetes, some individuals may experience a special phase named 'partial remission' or 'the honeymoon period', in which there is a transient recovery of beta cell function. Importantly, this stage of partial remission shows spontaneous immune downregulation, although the exact mechanisms are unclear. Intracellular energy metabolism is crucial for the differentiation and function of T cells, and provides promising targets for immunometabolic intervention strategies, but its role during partial remission is unknown. In this study, we aim to investigate the association between T cell intracellular glucose and fatty acid metabolism and the partial remission phase.

METHODS

This is a cross-sectional study with a follow-up component. Intracellular uptake of glucose and fatty acids by T cells was detected in participants with either new-onset type 1 diabetes or type 1 diabetes that was already in partial remission, and compared with heathy individuals and participants with type 2 diabetes. Subsequently, the participants with new-onset type 1 diabetes were followed up to determine whether they experienced a partial remission (remitters) or not (non-remitters). The trajectory of changes in T cell glucose metabolism was observed in remitters and non-remitters. Expression of programmed cell death-1 (PD-1) was also analysed to investigate possible mechanisms driving altered glucose metabolism. Partial remission was defined when patients had convalescent fasting or 2 h postprandial C-peptide >300 pmol/l after insulin treatment.

RESULTS

Compared with participants with new-onset type 1 diabetes, intracellular glucose uptake by T cells decreased significantly in individuals with partial remission. The trajectory of these changes during follow-up showed that intracelluar glucose uptake in T cells fluctuated during different disease stages, with a decreased uptake during partial remission that rebounded after remission. This dynamic in T cell glucose uptake was only detected in remitters and not in non-remitters. Further analysis demonstrated that changes of intracellular glucose uptake were found in subsets of CD4+ and CD8+ T cells, including Th17, Th1, CD8+ naive T cells (Tn) and CD8+ terminally differentiated effector memory T cells (Temra). Moreover, glucose uptake in CD8+ T cells was negatively related to PD-1 expression. The intracellular metabolism of fatty acids was not found to be different between new-onset participants and those in partial remission.

CONCLUSIONS/INTERPRETATION

Intracellular glucose uptake in T cells was specifically decreased during partial remission in type 1 diabetes and may be related to PD-1 upregulation, which may be involved in the down-modulation of immune responses during partial remission. This study suggests that altered immune metabolism could be a target for interventions at the point of diagnosis of type 1 diabetes.

IL-27 enhances peripheral B cell glycolysis of rheumatoid arthritis patients via activating mTOR signaling

Our previous study found that increased serum IL-27 could promote rheumatoid arthritis (RA) B cell dysfunction via activating mTOR signaling pathway. This study aimed to explore the effects of IL-27 on B cell metabolism and clarify the mechanisms via which IL-27 enhancing glycolysis to induce B cells hyperactivation. Peripheral CD19⁺ B cells were purified from healthy controls (HC) and RA patients and then cultured with or without anti-CD40/CpG and glycolysis inhibitor 2-deoxy-D-glucose (2-DG) or mTOR inhibitor rapamycin. Furthermore, the isolated CD19⁺ B cells were treated by HC serum or RA serum in the presence and absence of recombinant human IL-27 or anti-IL-27 neutralizing antibodies or 2-DG or rapamycin. The B cell glycolysis level, proliferation, differentiation and inflammatory actions were detected by qPCR, flow cytometry or ELISA. We found that the glycolysis in RA B cells was increased significantly compared with HC B cells. Glycolysis inhibition downregulated the proliferation, differentiation, and inflammatory actions of RA B cells. RA serum and IL-27 promoted B cell glycolysis, which could be obviously rescued by anti-IL-27 antibodies or mTOR inhibitor rapamycin. Our results suggest that the enhanced cellular glycolysis of RA B cells induced by IL-27 may contribute to B cells hyperactivation through activating the mTOR signaling pathway.

NAD+ Metabolism and Immune Regulation: New Approaches to Inflammatory Bowel Disease Therapies

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is a multifactorial systemic inflammatory immune response. Nicotinamide adenine dinucleotide (NAD⁺) is a co-enzyme involved in cell signaling and energy metabolism. Calcium homeostasis, gene transcription, DNA repair, and cell communication involve NAD⁺ and its degradation products. There is a growing recognition of the intricate relationship between inflammatory diseases and NAD⁺ metabolism. In the case of IBD, the maintenance of intestinal homeostasis relies on a delicate balance between NAD⁺ biosynthesis and consumption. Consequently, therapeutics designed to target the NAD⁺ pathway are promising for the management of IBD. This review discusses the metabolic and immunoregulatory processes of NAD⁺ in IBD to examine the molecular biology and pathophysiology of the immune regulation of IBD and to provide evidence and theoretical support for the clinical use of NAD⁺ in IBD.

Metabolic enzyme Suclg2 maintains tolerogenicity of regulatory dendritic cells diffDCs by suppressing Lactb succinylation

Metabolic reprogramming plays a pivotal role in the differentiation and function of immune cells including dendritic cells (DCs). Regulatory DCs can be generated in regional tissue niches like splenic stroma and act as an important part of stromal control of immune response for the maintenance of immune tolerance. However, the metabolic alterations during splenic stroma-driven regulatory DCs differentiation and the metabolic enzyme involved in regulatory DCs function remain poorly understood. By combining metabolomic, transcriptomic, and functional investigations of mature DCs (maDCs) and diffDCs (regulatory DCs differentiated from activated mature DCs through coculturing with splenic stroma), here we identified succinate-CoA ligase subunit beta Suclg2 as a key metabolic enzyme that reprograms the proinflammatory status of mature DCs into a tolerogenic phenotype via preventing NF-κB signaling activation. diffDCs downregulate succinic acid levels and increase the Suclg2 expression along with their differentiation from mature DCs. Suclg2-interference impaired the tolerogenic function of diffDCs in inducing T cell apoptosis and enhanced activation of NF-κB signaling and expression of inflammatory genes CD40, Ccl5, and Il12b in diffDCs. Furthermore, we identified Lactb as a new positive regulator of NF-κB signaling in diffDCs whose succinylation at the lysine 288 residue was inhibited by Suclg2. Our study reveals that the metabolic enzyme Suclg2 is required to maintain the immunoregulatory function of diffDCs, adding mechanistic insights into the metabolic regulation of DC-based immunity and tolerance.

PKM2/STAT1-mediated PD-L1 upregulation on neutrophils during sepsis promotes neutrophil organ accumulation by serving an anti-apoptotic role

BACKGROUND

Delayed neutrophil apoptosis during sepsis may impact neutrophil organ accumulation and tissue immune homeostasis. Elucidating the mechanisms underlying neutrophil apoptosis may help identify potential therapeutic targets. Glycolysis is critical to neutrophil activities during sepsis. However, the precise mechanisms through which glycolysis regulates neutrophil physiology remain under-explored, especially those involving the non-metabolic functions of glycolytic enzymes. In the present study, the impact of programmed death ligand-1 (PD-L1) on neutrophil apoptosis was explored. The regulatory effect of the glycolytic enzyme, pyruvate kinase M2 (PKM2), whose role in septic neutrophils remains unaddressed, on neutrophil PD-L1 expression was also explored.

METHODS

Peripheral blood neutrophils were isolated from patients with sepsis and healthy controls. PD-L1 and PKM2 levels were determined by flow cytometry and Western blotting, respectively. Dimethyl sulfoxide (DMSO)-differentiated HL-60 cells were stimulated with lipopolysaccharide (LPS) as an in vitro simulation of septic neutrophils. Cell apoptosis was assessed by annexin V/propidium iodide (annexin V/PI) staining, as well as determination of protein levels of cleaved caspase-3 and myeloid cell leukemia-1 (Mcl-1) by Western blotting. An in vivo model of sepsis was constructed by intraperitoneal injection of LPS (5 mg/kg) for 16 h. Pulmonary and hepatic neutrophil infiltration was assessed by flow cytometry or immunohistochemistry.

RESULTS

PD-L1 level was elevated on neutrophils under septic conditions. Administration of neutralizing antibodies against PD-L1 partially reversed the inhibitory effect of LPS on neutrophil apoptosis. Neutrophil infiltration into the lung and liver was also reduced in PD-L1-/- mice 16 h after sepsis induction. PKM2 was upregulated in septic neutrophils and promoted neutrophil PD-L1 expression both in vitro and in vivo. In addition, PKM2 nuclear translocation was increased after LPS stimulation, which promoted PD-L1 expression by directly interacting with and activating signal transducer and activator of transcription 1 (STAT1). Inhibition of PKM2 activity or STAT1 activation also led to increased neutrophil apoptosis.

CONCLUSION

In this study, a PKM2/STAT1-mediated upregulation of PD-L1 on neutrophils and the anti-apoptotic effect of upregulated PD-L1 on neutrophils during sepsis were identified, which may result in increased pulmonary and hepatic neutrophil accumulation. These findings suggest that PKM2 and PD-L1 could serve as potential therapeutic targets.

Git1-PGK1 interaction achieves self-protection against spinal cord ischemia-reperfusion injury by modulating Keap1/Nrf2 signaling

Spinal cord ischemia-reperfusion (IR) injury (SCIRI) is a significant secondary injury that causes damage to spinal cord neurons, leading to the impairment of spinal cord sensory and motor functions. Excessive reactive oxygen species (ROS) production is considered one critical mechanism of neuron damage in SCIRI. Nonetheless, the molecular mechanisms underlying the resistance of neurons to ROS remain elusive. Our study revealed that the deletion of Git1 in mice led to poor recovery of spinal cord motor function after SCIRI. Furthermore, we discovered that Git1 has a beneficial effect on neuron resistance to ROS production. Mechanistically, Git1 interacted with PGK1, regulated PGK1 phosphorylation at S203, and affected the intermediate products of glycolysis in neurons. The influence of Git1 on glycolysis regulates the dimerization of Keap1, which leads to changes in Nrf2 ubiquitination and plays a role in resisting ROS. Collectively, we show that Git1 regulates the Keap1/Nrf2 axis to resist ROS in a PGK1-dependent manner and thus is a potential therapeutic target for SCIRI.

Aroylated phenylenediamine HO53 modulates innate immunity, histone acetylation and metabolism

In the current context of antibiotic resistance, the need to find alternative treatment strategies is urgent. Our research aimed to use synthetized aroylated phenylenediamines (APDs) to induce the expression of cathelicidin antimicrobial peptide gene (CAMP) to minimize the necessity of antibiotic use during infection. One of these compounds, HO53, showed promising results in inducing CAMP expression in bronchial epithelium cells (BCi-NS1.1 hereafter BCi). Thus, to decipher the cellular effects of HO53 on BCi cells, we performed RNA sequencing (RNAseq) analysis after 4, 8 and 24 h treatment of HO53. The number of differentially expressed transcripts pointed out an epigenetic modulation. Yet, the chemical structure and in silico modeling indicated HO53 as a histone deacetylase (HDAC) inhibitor. When exposed to a histone acetyl transferase (HAT) inhibitor, BCi cells showed a decreased expression of CAMP. Inversely, when treated with a specific HDAC3 inhibitor (RGFP996), BCi cells showed an increased expression of CAMP, indicating acetylation status in cells as determinant for the induction of the expression of the gene CAMP expression. Interestingly, a combination treatment with both HO53 and HDAC3 inhibitor RGFP966 leads to a further increase of CAMP expression. Moreover, HDAC3 inhibition by RGFP966 leads to increased expression of STAT3 and HIF1A, both previously demonstrated to be involved in pathways regulating CAMP expression. Importantly, HIF1α is considered as a master regulator in metabolism. A significant number of genes of metabolic enzymes were detected in our RNAseq data with enhanced expression conveying a shift toward enhanced glycolysis. Overall, we are demonstrating that HO53 might have a translational value against infections in the future through a mechanism leading to innate immunity strengthening involving HDAC inhibition and shifting the cells towards an immunometabolism, which further favors innate immunity activation.

OPA1 drives macrophage metabolism and functional commitment via p65 signaling

Macrophages are essential players for the host response against pathogens, regulation of inflammation and tissue regeneration. The wide range of macrophage functions rely on their heterogeneity and plasticity that enable a dynamic adaptation of their responses according to the surrounding environmental cues. Recent studies suggest that metabolism provides synergistic support for macrophage activation and elicitation of desirable immune responses; however, the metabolic pathways orchestrating macrophage activation are still under scrutiny. Optic atrophy 1 (OPA1) is a mitochondria-shaping protein controlling mitochondrial fusion, cristae biogenesis and respiration; clear evidence shows that the lack or dysfunctional activity of this protein triggers the accumulation of metabolic intermediates of the TCA cycle. In this study, we show that OPA1 has a crucial role in macrophage activation. Selective Opa1 deletion in myeloid cells impairs M1-macrophage commitment. Mechanistically, Opa1 deletion leads to TCA cycle metabolite accumulation and defective NF-κB signaling activation. In an in vivo model of muscle regeneration upon injury, Opa1 knockout macrophages persist within the damaged tissue, leading to excess collagen deposition and impairment in muscle regeneration. Collectively, our data indicate that OPA1 is a key metabolic driver of macrophage functions.