SCENITH: A Flow Cytometry-Based Method to Functionally Profile Energy Metabolism with Single-Cell Resolution

Advances in Sampling and Analytical Techniques for Single-Cell Metabolomics: Exploring Cellular Heterogeneity

Single-cell metabolomics is an emerging and powerful technology that uncovers intercellular heterogeneity and reveals microenvironmental dynamics in both physiological and pathological conditions. This technology enables detailed observations of cellular interactions, providing valuable insights into processes such as aging, immune responses, and disease development. Despite significant advances, the need for detailed discussions on sampling and analytical methods in single-cell metabolomics continues to grow, with increasing focus on selecting the most suitable techniques for diverse research objectives. This review addresses these challenges by exploring key sampling and analytical strategies used in single-cell metabolomics. We focus on three main approaches: the capture and isolation of specific cell types, the precise aspiration of individual cells, and in situ mass spectrometry imaging. These methods are critically assessed to highlight strategies for achieving accurate metabolite detection at the single-cell level across diverse research applications.

A micro-metabolic rewiring assay for assessing hypoxia-associated cancer metabolic heterogeneity

Cancer metabolism plays an essential role in therapeutic resistance, where significant inter- and intra-tumoral heterogeneity exists. Hypoxia is a prominent driver of metabolic rewiring behaviors and drug responses. Recapitulating the hypoxic landscape in the tumor microenvironment thus offers unique insights into heterogeneity in metabolic rewiring and therapeutic responses, to inform better treatment strategies. There remains a lack of scalable tools that can readily interface with imaging platforms and resolve the heterogeneous behaviors in hypoxia-associated metabolic rewiring. Here we present a micro-metabolic rewiring (μMeRe) assay that provides the scalability and resolution needed to characterize the metabolic rewiring behaviors of different cancer cells in the context of hypoxic solid tumors. Our assay generates hypoxia through cellular metabolism without external gas controls, enabling the characterization of cell-specific intrinsic ability to drive hypoxia and undergo metabolic rewiring. We further developed quantitative metrics that measure the metabolic plasticity through phenotypes and gene expression. As a proof-of-concept, we evaluated the efficacy of a metabolism-targeting strategy in mitigating hypoxia- and metabolic rewiring-induced chemotherapeutic resistance. Our study and the scalable platform thus lay the foundation for designing more effective cancer treatments tailored toward specific metabolic rewiring behaviors.

Scavenging Reactive Oxygen Species by Cerium Oxide Nanoparticles Prevents Death in a Peripheral T Cell Lymphoma Preclinical Mouse Model

Cancer cell survival and proliferation are correlated with increased metabolic activity and consequent oxidative stress, driving metabolic shifts that interfere with the immune response to malignant cells. This is the case of high-energy-demanding angioimmunoblastic T cell lymphoma (AITL), a highly aggressive cancer with poor survival rates, where malignant CD4+ PD-1high T cells show increased mitochondrial activity and Reactive oxygen species (ROS) accumulation. Here, we report that administration of ROS scavenging cerium oxide (CeO2) nanoparticles in an AITL preclinical mouse model leads to their preferential accumulation in the spleen, where the CD4+ PD-1high T cells driving malignancy were significantly reduced. This was accompanied by activation of previously exhausted cytotoxic CD8+ T cells, restoring their potent antitumor function. As a result, survival rates dramatically increase with no observed toxicity to healthy cells or tissues. Overall, it highlights the correlation between increased energy demand, increased mitochondrial mass, increased PD-1 expression, increased ROS production, and immune suppression and how this vicious loop can be stopped by scavenging ROS.

Dietary lipid overload creates a suppressive environment that impedes the antiviral functions of NK cells

Natural killer (NK) cells are innate immune cells able to recognize and eliminate virus-infected cells. NK cell activity strongly correlates with a metabolic reprogramming and breakdown of fatty acids by β-oxidation during virus infections. However, there is limited knowledge regarding the impact of obesity on antiviral NK cell functions. Here, employing the Friend retrovirus mouse model, we show that the cytotoxicity and cytokine production of NK cells was impaired in obesity, leading to higher viral loads. NK cells suppression in obesity was mediated by activated Tregs. Furthermore, obese mice that were switched back to a regular diet showed complete recovery of the NK cell activity. Interestingly, feeding mice with a high-fat diet (HFD) for just ten days caused NK cell dysfunction and increased retroviral burden. This study is the first to link the detrimental impact of an obesity-induced immunosuppressive microenvironment with NK cell dysfunction during an acute retroviral infection.

Malonate promotes CD8+ T cell memory formation via protein malonylation

Protein malonylation represents a recently identified posttranslational modification whose role in CD8+ T cell differentiation and functionality remains incompletely understood. In this study, we demonstrate that enhancing protein malonylation through sodium malonate (SM) treatment promotes CD8+ T cell memory formation in response to bacterial infection, subsequently potentiating recall responses. Comparative metabolomic analysis between SM-treated and control CD8+ T cells revealed significant metabolic alterations associated with protein malonylation. We present the first comprehensive proteomic analysis of lysine malonylation in murine CD8+ T cells, identifying 77 malonylation sites across 64 proteins involved in diverse cellular processes, particularly metabolic pathways. Malonylation of STAT6 was confirmed via the use of a specific chemical probe. Notably, we established that malonylation at the lysine 374 site of STAT6 results in increased TCF1 expression, due to alleviated transcriptional repression of TCF1 by STAT6. Collectively, our findings provide compelling evidence that protein malonylation plays a significant role in regulating CD8+ T cell memory formation.

Metabolic reprogramming of interleukin-17-producing γδ T cells promotes ACC1-mediated de novo lipogenesis under psoriatic conditions

Metabolic reprogramming determines γδ T cell fate during thymic development; however, the metabolic requirements of interleukin (IL)-17A-producing γδ T cells (γδT17 cells) under psoriatic conditions are unclear. Combining high-throughput techniques, including RNA sequencing, SCENITH, proteomics and stable isotope tracing, we demonstrated that psoriatic inflammation caused γδT17 cells to switch toward aerobic glycolysis. Under psoriatic conditions, γδT17 cells upregulated ATP-citrate synthase to convert citrate to acetyl-CoA, linking carbohydrate metabolism and fatty acid synthesis (FAS). Accordingly, we used a pharmacological inhibitor, Soraphen A, which blocks acetyl-CoA carboxylase (ACC), to impair FAS in γδT17 cells, reducing their intracellular lipid stores and ability to produce IL-17A under psoriatic conditions in vitro. We pinpointed the pathogenic role of ACC1 in γδT17 cells in vivo by genetic ablation, ameliorating inflammation in a psoriatic mouse model. Furthermore, ACC inhibition limited human IL-17A-producing γδT17 cells. Targeting ACC1 to attenuate pathogenic γδT17 cell function has important implications for psoriasis management.

Uptake of lipids from ascites drives NK cell metabolic dysfunction in ovarian cancer

High-grade serous ovarian cancer (HGSOC) remains an urgent unmet clinical need, with more than 70% of patients presenting with metastatic disease. Many patients develop large volumes of ascites, which promotes metastasis and is associated with poor therapeutic response and survival. Immunotherapy trials have shown limited success, highlighting the need to better understand HGSOC immunology. Here, we analyzed cytotoxic lymphocytes [natural killer (NK), T, and innate T cells] from patients with HGSOC and observed widespread dysfunction across primary and metastatic sites. Although nutrient rich, ascites was immunosuppressive for all lymphocyte subsets. NK cell dysfunction was driven by uptake of polar lipids, with associated dysregulation in lipid storage. Phosphatidylcholine was a key immunosuppressive metabolite, disrupting NK cell membrane order and cytotoxicity. Blocking lipid uptake through SR-B1 protected NK cell antitumor functions in ascites. These findings offer insights into immune suppression in HGSOC and have important implications for the design of future immunotherapies.

De Novo Protein Synthesis Occurs Through the Cytoplasmic Translation Machinery in Mammalian Spermatozoa

The current hypothesis suggests that translation occurs in capacitated spermatozoa through mitochondrial ribosomes. Mitochondrial translation has several particularities, which rise some questions about how mitochondrial ribosomes can ensure sperm translation activity. Here, we aimed to elucidate if cytoplasmic translation occurs in mammalian spermatozoa. A bioinformatic workflow was performed to identify translation-related proteins in human spermatozoa and their association with cytoplasmic translation. The surface sensing of translation (SUnSET) method was used to measure translation activity in capacitated human and bovine spermatozoa. Two translation inhibitors, cycloheximide (CHX, cytoplasmic) and D-chloramphenicol (D-CP, mitochondrial) were used to identify which ribosomes were active in sperm. To spot newly synthesized proteins, puromycin-peptides were immunoprecipitated and analysed by mass spectrometry. A second approach was performed using translation inhibitors and analysing the sperm proteome by mass spectrometry. Bioinformatic analysis revealed that human spermatozoa possess 510 translation proteins, which were enriched for cytoplasmic mRNA translation. CHX decreased translation activity in mammalian sperm, whereas no effect was observed after D-CP treatment. Nine proteins were immunoprecipitated and identified as newly synthesized in capacitated bovine spermatozoa. CHX and D-CP decreased the level of 22 proteins that were replaced, or de novo translated during capacitation. New proteins were associated with relevant processes for sperm physiology. Both translation inhibitors decreased sperm rapid progressive motility and increased sperm immotility. Our results proved sperm translation occurs through cytoplasmic translation machinery in capacitated bovine and human spermatozoa. These results also support that sperm translation is required during capacitation to produce relevant proteins for sperm functions.

Metabolism in hematology: Technological advances open new perspectives on disease biology and treatment

The term metabolism refers to the multi-faceted biochemical reactions within a cell or an organism that occur to maintain energy homeostasis, cell growth, and oxidative balance. Cells possess a high metabolic plasticity, allowing them to adapt to the dynamic requirements of their functional state and environment. Deregulated cellular metabolism is a hallmark of many diseases, including benign and malignant hematological conditions. In the last decade, multiple technological innovations in the metabolism field have made in-depth metabolic analysis broadly applicable. Such studies are shedding new light on normal and malignant hematopoiesis and open avenues to a better understanding of the biology of hematological diseases. In this review, we will first give a brief overview of central metabolic processes. Furthermore, we discuss the most commonly used methods to study metabolism. We begin by elaborating on the use of next-generation sequencing to detect metabolism-related genomic mutations and study transcriptional signatures. Furthermore, we discuss methods for measuring protein expression, such as mass spectrometry (MS), flow cytometry, and cytometry time-of-flight. Next, we describe the use of nuclear magnetic resonance spectroscopy, MS, and flow cytometry for metabolite quantification. Finally, we highlight functional assays to probe metabolic pathways in real-time. We illustrate how these technologies and their combination have advanced our understanding of the role of metabolism. Our goal is to provide hematologists with a comprehensive guide to modern techniques in metabolism research, their benefits and disadvantages, and how they guide our understanding of disease and potentially future personalized therapy decisions.

Restoring mitochondrial function promotes hematopoietic reconstitution from cord blood following cryopreservation-related functional decline

Umbilical cord blood (UCB) plays substantial roles in hematopoietic stem cell (HSC) transplantation and regenerative medicine. UCB is usually cryopreserved for years before use. It remains unclear whether and how cryopreservation affects UCB function. We constructed a single-cell transcriptomics profile of CD34+ hematopoietic stem and progenitor cells (HSPCs) and mononuclear cells (MNCs) from fresh and cryopreserved UCB stored for 1, 5, 10, and 19 years. Compared with fresh UCB, cryopreserved HSCs and multipotent progenitors (MPPs) exhibited more active cell-cycle and lower expression levels of HSC and multipotent progenitor signature genes. Hematopoietic reconstitution of cryopreserved HSPCs gradually decreased during the first 5 years but stabilized thereafter, aligning with the negative correlation between clinical neutrophil engraftment and cryopreservation duration of UCB. Cryopreserved HSPCs also showed reduced megakaryocyte generation. In contrast, cryopreserved NK cells and T cells maintained a capacity for cytokine production and cytotoxicity comparable to that of fresh cells. Mechanistically, cryopreserved HSPCs exhibited elevated ROS, reduced ATP synthesis, and abnormal mitochondrial distribution, which collectively led to attenuated hematopoietic reconstitution. These effects could be ameliorated by sulforaphane (SF). Together, we elucidate the negative effect of cryopreservation on UCB HSPCs and identify SF as a mitigation strategy, broadening the temporal window and scope for clinical applications of cryopreserved UCB.

Development of Itaconate Polymers Microparticles for Intracellular Regulation of Pro-Inflammatory Macrophage Activation

Itaconate (IA) is an endogenous metabolite and a potent regulator of the innate immune system. It's use in immunomodulatory therapies has faced limitations due to challenges in controlled delivery and requirements of high extracellular concentrations for internalization of the highly polar small molecule to achieve its intracellular therapeutic activity. Microparticle (MP)-based delivery strategies are a promising approach for intracellular delivery of small molecule metabolites through macrophage phagocytosis and subsequent intracellular polymer degradation-based delivery. Toward the goal of intracellular delivery of IA, degradable polyester polymer- (poly(dodecyl itaconate)) based IA polymer microparticles (IA-MPs) are generated using an emulsion method, forming micron-scale (≈1.5 µm) degradable microspheres. IA-MPs are characterized with respect to their material properties and IA release kinetics to inform particle fabrication. Treatment of murine bone marrow-derived macrophages with an optimized particle concentration of 0.1 mg million-1 cells enables phagocytosis-mediated internalization and low levels of cytotoxicity. Flow cytometry demonstrates IA-MP-specific regulation of IA-sensitive inflammatory targets. Metabolic analyses demonstrate that IA-MP internalization inhibits oxidative metabolism and induced glycolytic reliance, consistent with the established mechanism of IA-associated inhibition of succinate dehydrogenase. This development of IA-based polymer microparticles provides a basis for additional innovative metabolite-based microparticle drug delivery systems for the treatment of inflammatory disease.

Dissecting inflammation in the immunemetabolomic era

The role of immune metabolism, specific metabolites and cell-intrinsic and -extrinsic metabolic states across the time course of an inflammatory response are emerging knowledge. Targeted and untargeted metabolomic analysis is essential to understand how immune cells adapt their metabolic program throughout an immune response. In addition, metabolomic analysis can aid to identify pathophysiological patterns in inflammatory disease. Here, we discuss new metabolomic findings within the transition from inflammation to resolution, focusing on three key programs of immunity: Efferocytosis, IL-10 signaling and trained immunity. Particularly the tryptophan-derived metabolite kynurenine was identified as essential for efferocytosis and inflammation resolution as well as a potential biomarker in diverse inflammatory conditions. In summary, metabolomic analysis and integration with transcriptomic and proteomic data, high resolution imaging and spatial information is key to unravel metabolic drivers and dependencies during inflammation and progression to tissue-repair.

Long-term histone lactylation connects metabolic and epigenetic rewiring in innate immune memory

Trained immunity, a de facto innate immune memory characterized by enhanced responsiveness to future challenges, is underpinned by epigenetic and metabolic rewiring. In individuals vaccinated with Bacille Calmette-Guérin (BCG), lactate release was associated with enhanced cytokine responsiveness upon restimulation. Trained monocytes/macrophages are characterized by lactylation of histone H3 at lysine residue 18(H3K18la), mainly at distal regulatory regions. Histone lactylation was positively associated with active chromatin and gene transcription, persisted after the elimination of the training stimulus, and was strongly associated with "trained" gene transcription in response to a secondary stimulus. Increased lactate production upon induction of trained immunity led to enhanced production of proinflammatory cytokines, a process associated with histone lactylation. Pharmacological inhibition of lactate production or histone lactylation blocked trained immunity responses, while polymorphisms of LDHA and EP300 genes modulated trained immunity. Long-term histone lactylation persisted in vivo 90 days after vaccination with BCG, highlighting H3K18la as an epigenetic mark of innate immune memory.

A new method to measure cell metabolism of rare cells in vivo reveals a high oxidative phosphorylation dependence of lung T cells

Regulation of cellular metabolism is a central element governing the fate and function of T cells. However, the in vivo metabolic characteristics of rare cells, such as nonlymphoid tissue T cells, are poorly understood because of experimental limitations. Most techniques measuring cell metabolism require large cell numbers. The recent SCENITH method allows for studying the metabolism of rare cells by flow cytometry. However, this technique requires cells to be isolated and cultured ex vivo, which may alter their metabolism. Here, we propose a new experimental approach, called in vivo SCENITH, to investigate the cellular metabolism of T cells in vivo at a steady state in the spleen and lungs. For this purpose, we administered the metabolic modulators directly in mice, instead of applying these reagents ex vivo, as in the classical SCENITH method. Whereas ex vivo manipulation impacted the viability and phenotype of T cells, this toxic effect was not observed in the in vivo SCENITH. We observed that conventional and regulatory T cells shared similar metabolic profiles. Importantly, whereas spleen T cells used both oxidative phosphorylation and glycolysis, the metabolism of T cells in the lungs was mainly based on oxidative phosphorylation. Finally, metabolic inhibitors that interfere with protein translation and energy availability downregulated Foxp3 expression in regulatory T cells. These results describe an expansion of SCENITH that allows to measure the metabolic profile of rare cells in vivo, revealing a high dependence on oxidative phosphorylation of lung T cells.

Cancer-cell-derived cGAMP limits the activity of tumor-associated CD8+ T cells

Using a mouse tumor model with inducible cancer-cell-intrinsic cyclic GMP-AMP (cGAMP) synthase (cGAS) expression, we show that cancer-cell-derived cGAMP is essential and sufficient to trigger a sustained type I interferon response within the tumor microenvironment. This leads to improved CD8+ T cell-dependent tumor restriction. However, cGAMP limits the proliferation, survival, and function of stimulator of IFN genes (STING)-expressing, but not of STING-deficient, CD8+ T cells. In vivo, STING deficiency in CD8+ T cells enhances tumor restriction. Consequently, cancer-cell-derived cGAMP both drives and limits the anti-tumor potential of CD8+ T cells. Mechanistically, T cell-intrinsic STING is associated with pro-apoptotic and antiproliferative gene signatures. Our findings suggest that STING signaling acts as a checkpoint in CD8+ T cells that balances tumor immunity.

Human γδ T Cell Function Is Impaired Upon Mevalonate Pathway Inhibition

Vδ2 T cells, a predominant human peripheral γδ T cell population, are a promising candidate for the development of immunotherapies against cancer and infected cells. Aminobisphosphonate drugs, such as zoledronate, are commonly used to expand Vδ2 T cells. Yet, such in vitro generated cells have limited efficacy in the clinic. We found that despite inducing excessive proliferation of Vδ2 T cells, zoledronate impaired their effector function and caused the upregulation of the inhibitory receptor TIM3. This effect was due to the inhibition of mevalonate metabolism and dysregulation of downstream biological processes such as protein prenylation and intracellular signalling. In vitro and in vivo inhibition of mevalonate metabolism with zoledronate, statins, and 6-fluoromevalonate, as well as genetic deficiency of the mevalonate kinase, all resulted in compromised cytokine and cytotoxic molecule production by Vδ2 T cells. Impaired Vδ2 T cell function was accompanied by transcriptome and kinome changes. Our findings reveal the importance of mevalonate metabolism for the proper functioning of Vδ2 T cells. This observation provides important considerations for improving their therapeutic use and has repercussions for patients with statin or aminobisphosphonate treatments.

The metabolic sensor LKB1 regulates ILC3 homeostasis and mitochondrial function

Group 3 innate lymphoid cells (ILC3s) are tissue-resident cells that sense environmental cues, control infections, and promote tissue homeostasis at mucosal surfaces. The metabolic sensor liver kinase B1 (LKB1) integrates intracellular stress, metabolism, and mitochondrial function to promote the development and effector functions of a variety of immune cells; however, the role of LKB1 in ILC3 function was unknown. Here, we show that LKB1 is crucial for adult ILC3 homeostasis, cytokine production, and mitochondrial function. ILC3-specific LKB1 deletion resulted in a reduced number of ILC3s and interleukin-22 (IL-22) production. LKB1-deficient ILC3s had decreased survival, mitochondrial dysfunction, cytoplasmic lipid accumulation, and altered bioenergetics. Using LKB1 downstream kinase modulators, we found that LKB1 regulation of ILC3 survival and IL-22 production requires signaling through microtubule affinity-regulating kinases (MARKs). Mechanistically, LKB1 deficiency resulted in increased reactive oxygen species (ROS) production and NFAT2 and PD-1 expression. Our work reveals that metabolic regulation of enteric ILC3 function by an LKB1-dependent signaling network is crucial for intestinal immunity and tissue homeostasis.

Mitochondrial protein OPA1 is required for the expansion of effector CD8 T cells

Short-lived effector cells are characterized metabolically by a highly glycolytic state, driving energy and biomass acquisition, whereas memory-fated T cells have historically been described as meeting these requirements through mitochondrial metabolism. Here, we show that the mitochondrial protein optic atrophy 1 (OPA1) is critical for rapidly dividing CD8 T cells in vivo, the requirement for which is most pronounced in effector CD8 T cells. More specifically, OPA1 supports proper cell cycle initiation and progression and the viability and survival of CD8 T cells during clonal expansion. Use of mice deficient in the mitochondrial membrane fusion proteins Mitofusin 1 and 2 (MFN1/2) in both in vivo proliferation/differentiation assays and ex vivo metabolic analysis indicates that the requirement for OPA1 during cell division supersedes its role in mitochondrial fusion. We conclude that OPA1 is critical for the generation and accumulation of short-lived effector cells that arise during the response to infection.

Elevated mitochondrial membrane potential is a therapeutic vulnerability in Dnmt3a-mutant clonal hematopoiesis

The competitive advantage of mutant hematopoietic stem and progenitor cells (HSPCs) underlies clonal hematopoiesis (CH). Drivers of CH include aging and inflammation; however, how CH-mutant cells gain a selective advantage in these contexts is an unresolved question. Using a murine model of CH (Dnmt3aR878H/+), we discover that mutant HSPCs sustain elevated mitochondrial respiration which is associated with their resistance to aging-related changes in the bone marrow microenvironment. Mutant HSPCs have DNA hypomethylation and increased expression of oxidative phosphorylation gene signatures, increased functional oxidative phosphorylation capacity, high mitochondrial membrane potential (Δψm), and greater dependence on mitochondrial respiration compared to wild-type HSPCs. Exploiting the elevated Δψm of mutant HSPCs, long-chain alkyl-TPP molecules (MitoQ, d-TPP) selectively accumulate in the mitochondria and cause reduced mitochondrial respiration, mitochondrial-driven apoptosis and ablate the competitive advantage of HSPCs ex vivo and in vivo in aged recipient mice. Further, MitoQ targets elevated mitochondrial respiration and the selective advantage of human DNMT3A-knockdown HSPCs, supporting species conservation. These data suggest that mitochondrial activity is a targetable mechanism by which CH-mutant HSPCs gain a selective advantage over wild-type HSPCs.

A new era in melanoma immunotherapy: focus on DCs metabolic reprogramming

Melanoma, being one of the most dangerous forms of skin cancer, is characterized by its aggressive and metastatic nature, with the potential to develop resistance to various treatments. This resistance makes the disease challenging to treat, emphasizing the need for new treatment strategies. Within the tumor microenvironment (TME), melanoma cells exploit metabolic shifts, particularly glycolysis, to create an immunosuppressive TME that prevents dendritic cells (DCs) from functioning properly. Essential metabolic alterations such as lactate and lipid accumulation, and lack of tryptophan disrupt DC maturation, antigen presentation, and T cell activation. In recent years, melanoma immunotherapy has increasingly focused on reprogramming the metabolism of DCs. This review paper aims to provide insights into the metabolic suppression of melanoma-associated DCs, allowing the design of therapeutic strategies based on metabolic interventions to promote or restore DC function. This contribution reviews the metabolic reprogramming of DCs as a new approach for melanoma immunotherapy.

Polychlorinated biphenyls induce immunometabolic switch of antiinflammatory macrophages toward an inflammatory phenotype

Polychlorinated biphenyls (PCBs) are a group of environmental toxicants associated with increased risk of diabetes, obesity, and metabolic syndrome. These metabolic disorders are characterized by systemic and local inflammation within adipose tissue, the primary site of PCB accumulation. These inflammatory changes arise when resident adipose tissue macrophages undergo phenotypic plasticity-switching from an antiinflammatory to an inflammatory phenotype. Thus, we sought to assess whether PCB exposure drives macrophage phenotypic switching. We investigated how human monocyte-derived macrophages polarized toward an M1, M2a, or M2c phenotype were impacted by exposure to Aroclor 1254, a PCB mixture found at high levels in school air. We showed that PCB exposure not only exacerbates the inflammatory phenotype of M1 macrophages but also shifts both M2a and M2c cells toward a more inflammatory phototype in both a dose- and time-dependent manner. Additionally, we show that PCB exposure leads to significant metabolic changes. M2 macrophages exposed to PCBs exhibit increased reliance on aerobic glycolysis and reduced capacity for fatty acid and amino acid oxidation-both indicators of an inflammatory macrophage phenotype. Collectively, these results demonstrate that PCBs promote immunometabolic macrophage plasticity toward a more M1-like phenotype, thereby suggesting that PCBs exacerbate metabolic diseases by altering the inflammatory environment in adipose tissue.

IgA2 ACPA Drives a Hyper-Inflammatory Phenotype in Macrophages via ATP Synthase and COX2

IgA can form immune complexes (ICs) and activate myeloid cells via Fc alpha receptor-mediated signalling to secrete pro-inflammatory cytokines. It was previously described that of the two IgA subclasses (IgA1 and IgA2), IgA2 is more inflammatory than IgA1. However, the mechanisms underlying this differential pro-inflammatory potential remain poorly defined. Using anti-citrullinated protein IgA1 and IgA2 antibodies (ACPA) that are commonly found in rheumatoid arthritis (RA) patients and linked to chronic inflammation, we show here that, in macrophages, IgA2-ICs boost TLR-induced TNF and IL6 secretion, COX2 expression, and production of COX2-dependent lipid mediators to a higher level than IgA1-ICs. Metabolically, we found the amplification of TLR-induced cytokine production and COX2 induction by IgA2-ICs to be dependent on mitochondrial ATP synthesis, but not glycolysis. Finally, we found the potentiation of TLR-induced cytokine production by IgA-ICs to be COX2-dependent. Together this work points towards a key role for mitochondrial ATP synthesis in driving COX2 expression and subsequent IgA2-IC-dependent potentiation of TLR-induced cytokine production by macrophages. As such, our work provides new insights into the mechanisms underlying IgA2-induced inflammation in the context of RA. Thus, this may hold novel clues to be explored as therapeutic possibilities to target antibody-driven inflammation in chronic inflammatory diseases.

The cell origin of reactive oxygen species and its implication for evolutionary trade-offs

The allocation of resources in animals is shaped by adaptive trade-offs aimed at maximizing fitness. At the heart of these trade-offs, lies metabolism and the conversion of food resources into energy, a process mostly occurring in mitochondria. Yet, the conversion of nutrients to utilizable energy molecules (adenosine triphosphate) inevitably leads to the by-production of reactive oxygen species (ROS) that may cause damage to important biomolecules such as proteins or lipids. The 'ROS theory of ageing' has thus proposed that the relationship between lifespan and metabolic rate may be mediated by ROS production. However, the relationship is not as straightforward as it may seem: not only are mitochondrial ROS crucial for various cellular functions, but mitochondria are also actually equipped with antioxidant systems, and many extra-mitochondrial sources also produce ROS. In this review, we discuss how viewing the mitochondrion as a regulator of cellular oxidative homeostasis, not merely a ROS producer, may provide new insights into the role of oxidative stress in the reproduction-survival trade-off. We suggest several avenues to test how mitochondrial oxidative buffering capacity might complement current bioenergetic and evolutionary studies.

Microbiota promote enhanced CD39 expression in γδ intraepithelial lymphocytes through the activation of TCR and IL-15 signaling

Intraepithelial lymphocytes expressing the γδ T cell receptor (γδ IEL) provide continuous surveillance of the intestinal epithelium. We report that mice harboring a microbiota-specific hyperproliferative γδ IEL (γδ HYP ) phenotype also upregulate the expression of the ectonucleotidase CD39, a marker of regulatory γδ T cells. Enhanced TCR and IL-15 signaling correlates with a progression from a naïve-like CD39 neg γδ IEL to a more mature, tissue-adapted CD39 hi IEL population. We found that TCRγδ activation drives CD122-mediated CD39 upregulation on γδ HYP IELs and increased mucosal IL-15 further amplifies CD39 expression in these cells. Further investigation revealed that CD39 induction requires sustained exposure to the γδ HYP -associated microbiota. Moreover, CD39 hi γδ IELs exhibit a reduced capacity to produce pro-inflammatory cytokine, which may explain the lack of histopathology in γδ HYP mice. Overall, our study identifies a previously unappreciated mechanism by which an altered microbiota amplifies CD39 expression on γδ HYP IELs, leading to the expansion of γδ IELs with regulatory potential.

A novel multigene panel (Sig27) robustly predicts poor prognosis of renal cell carcinoma via high-level associations with immunosuppressive features

BACKGROUND

We investigated a 27-gene panel (Sig27), derived from prostate cancer, for risk stratification of RCC (clear cell RCC/ccRCC, papillary RCC/pRCC, and chromophobe RCC/chRCC).

METHODS

Sig27 gene expressions were examined in 960 RCC and 201 kidney tissues. Sig27 was evaluated for predicting overall survival (OS), association with immune checkpoints (IC), regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSC), and tumor-associated macrophages (TAM) in RCC.

RESULTS

Sig27 robustly predicts OS of ccRCC, pRCC, and chRCC. Sig27 stratifies high-risk ccRCCs: median survival month (MSM) 19.3 and 80.4% of deaths and high-risk pRCCs (MSM 19.6 and 58.6% of death) compared to low-risk ccRCCs (2.9% of death) and pRCCs (2.7% of fatality). Sig27 contains several novel genes related to the RCC immunosuppressive features. FPR3, NOD2, MCTP1, LAMP3, TFEC, and FAM65B are highly correlated with MDSC, Treg, TAM and multiple (≥12) ICs in RCCs. FPR3 and NOD2 are pattern recognition receptors and initiate proinflammatory responses via sensing pathogen-associated molecular patterns and damage-associated molecular patterns; their upregulations may contribute to chronic inflammation in RCC. The Sig27 metagene is expressed in ccRCC-associated immune cells: exhausted CD8T cells, TAM, Treg, and others.

CONCLUSIONS

Sig27 is a novel and effective pan-RCC biomarker with high-level associations with RCC immunosuppressive features.

Immunometabolic analysis of primary murine group 2 innate lymphoid cells: a robust step-by-step approach

Group 2 Innate Lymphoid Cells (ILC2s) have recently been shown to exert key regulatory functions in both innate and adaptive immune response networks that drive the establishment and progression of type 2 immunity. Although mainly tissue resident, ILC2s and their crosstalk within tissue microenvironments influence metabolism at both the local and systemic levels. In turn, the energetic demand and metabolic status within these systems shape the diverse phenotypes and effector functions of ILC2s. Deciphering these metabolic networks in ILC2s is therefore essential in understanding their various roles in health as well as their associated pathophysiologies. Here we detail a framework of experimental approaches to study key immunometabolic states of primary murine ILC2s and link them to unique phenotypes and their corresponding functionality. Utilizing flow cytometry, Single Cell ENergetic metabolism by profilIng Translation inHibition (SCENITH), and the Seahorse platform we provide a framework that allows in-depth analysis of cellular bioenergetic states to determine the immunometabolic wiring of ILC2s. Connecting immunometabolic states and networks to ILC2 phenotypes and effector functions with this method will allow future in-depth studies to assess the potential of novel pharmaceutics in altering ILC2 functionality in clinical settings.

Mitochondria sense bacterial lactate and drive release of neutrophil extracellular traps

Neutrophils induce oxidative stress, creating a harsh phagosomal environment. However, Staphylococcus aureus can survive these conditions, requiring neutrophils to deploy mechanisms that sense bacterial persistence. We find that staphylococcal lactate is a metabolic danger signal that triggers neutrophil extracellular trap release (NETosis). Neutrophils coordinate mitochondria in proximity to S. aureus-containing phagosomes, allowing transfer of staphylococcal lactate to mitochondria where it is rapidly converted into pyruvate and causes mitochondrial reactive oxygen species, a precursor to NETosis. Similar results were observed in response to phylogenetically distinct bacteria, implicating lactate accumulation as a broad signal triggering NETosis. Furthermore, patients with systemic lupus erythematosus (SLE) are more susceptible to bacterial infections. We find that SLE neutrophils cannot sense bacterial lactate impairing their capacity to undergo NETosis upon S. aureus infection but initiate aberrant NETosis triggered by apoptotic debris. Thus, neutrophils adapt mitochondria as sensory organelles that detect bacterial metabolic activity and dictate downstream antibacterial processes.

CD105 blockade restores osimertinib sensitivity in drug-resistant EGFR-mutant non-small cell lung cancer

AIM

To investigate the role of CD105 in mediating drug resistance to EGFR-targeted therapy in non-small cell lung cancer (NSCLC).

METHODS

Imaging mass cytometry was conducted on 66 NSCLC tumors, 44 of which had EGFR mutations. We correlated clinical variables, including overall survival, with CD105 (endoglin) expression, a co-receptor for bone morphogenetic protein (BMP) signaling. Two osimertinib-resistant EGFR-mutant cell lines were developed to study the effects of EGFR and CD105 disruption. Single cell RNA sequencing of the isogenic parental and osimertinib resistant lines was performed. Additionally, ATAC sequencing and Single Cell ENergetIc metabolism by profiling Translation inHibition analysis (SCENITH) was used to assess promoter chromatin status and glycolytic state.

RESULTS

We found a negative correlation between CD105 expression and overall survival in patients. Treatment with osimertinib or EGFR knockdown significantly elevated CD105 expression in EGFR-mutant cell lines. Single-cell RNA sequencing identified a subset of cells with heightened endothelial characteristics and altered pyrimidine metabolism, associated with osimertinib resistance. These cells exhibited a slow-cycling behavior, characterized by elevated chromatin condensation and reduced glycolysis. Combining osimertinib with carotuximab, a CD105 neutralizing antibody, significantly reduced the slow-cycling transcriptomic signature, increased chromatin accessibility, and restored glycolysis compared to osimertinib treatment alone. Mass spectrometry confirmed that carotuximab re-engaged EGFR signaling by coupling it with CD105. Consequently, carotuximab re-sensitized resistant tumors to osimertinib by increasing their mitotic index and ERK signaling in mouse models.

CONCLUSION

Carotuximab effectively reduced the slow-cycling cell population and restored osimertinib sensitivity, offering a promising strategy for managing refractory NSCLC.

Entinostat, a histone deacetylase inhibitor, enhances CAR-NK cell anti-tumor activity by sustaining CAR expression

Allogeneic natural killer (NK) cell therapy has demonstrated significant potential in cancer immunotherapy by harnessing NK cells to target malignancies. CD138-targeting chimeric antigen receptor (CAR)-engineered NK cells offer a promising therapeutic option for multiple myeloma (MM). However, sustaining CAR expression on CAR-NK cells during ex vivo expansion poses a challenge to developing effective immunotherapies. In this study, primary NK cells were isolated, cryopreserved, and modified to express anti-CD138 CARs through retroviral transduction. Histone deacetylase inhibitors (HDACi), particularly entinostat (ENT), were applied to enhance CAR expression stability in CAR-NK cells. Our findings indicate that ENT treatment significantly improves and maintains CAR expression, thereby enhancing the cytotoxic activity of CAR-NK cells against CD138-positive multiple myeloma cells. ENT-treated CAR-NK cells exhibited prolonged persistence and more significant tumor reduction in an MM tumor-bearing mouse model, highlighting the therapeutic potential of HDACi-treated CAR-NK cells. This study provides the first evidence that HDAC inhibitors can sustain CAR expression in CAR-NK cells in a promoter-dependent manner, potentially enhancing anti-tumor efficacy in multiple myeloma and underscoring the possible need for further clinical evaluation.

Oxidative phosphorylation is a key feature of neonatal monocyte immunometabolism promoting myeloid differentiation after birth

Neonates primarily rely on innate immune defense, yet their inflammatory responses are usually restricted compared to adults. This is controversially interpreted as a sign of immaturity or essential programming, increasing or decreasing the risk of sepsis, respectively. Here, combined transcriptomic, metabolic, and immunological studies in monocytes of healthy individuals reveal an inverse ontogenetic shift in metabolic pathway activities with increasing age. Neonatal monocytes are characterized by enhanced oxidative phosphorylation supporting ongoing myeloid differentiation. This phenotype is gradually replaced during early childhood by increasing glycolytic activity fueling the inflammatory responsiveness. Microbial stimulation shifts neonatal monocytes to an adult-like metabolism, whereas ketogenic diet in adults mimicking neonatal ketosis cannot revive a neonate-like metabolism. Our findings disclose hallmarks of innate immunometabolism during healthy postnatal immune adaptation and suggest that premature activation of glycolysis in neonates might increase their risk of sepsis by impairing myeloid differentiation and promoting hyperinflammation.

Circadian Rhythm Disruption Exacerbates Autoimmune Uveitis: The Essential Role of PER1 in Treg Cell Metabolic Support for Stability and Function

Circadian rhythm plays a critical role in the progression of autoimmune diseases. While our previous study demonstrated the therapeutic effects of melatonin in experimental autoimmune uveitis, the involvement of circadian rhythm remained unclear. Using a light-induced circadian rhythm disruption model, we showed that disrupted circadian rhythms exacerbate autoimmune uveitis by impairing the stability and function of Treg cells. Mechanistically, we identified the core clock gene Per1, which is significantly reduced under circadian disruption, is essential for Treg cell metabolism and immunoregulatory function. This study underscores the pivotal role of circadian rhythm-related Treg cells in autoimmune disease progression.

Maresin-1 promotes neuroprotection and modulates metabolic and inflammatory responses in disease-associated cell types in preclinical models of multiple sclerosis

Multiple sclerosis (MS) is a prevalent inflammatory neurodegenerative disease in young people, causing neurological abnormalities and impairment. To investigate a novel therapeutic agent for MS, we observed the impact of maresin 1 (MaR1) on disease progression in a well-known, relapsing-remitting experimental autoimmune encephalomyelitis mouse model. Treatment with MaR1 accelerated inflammation resolution, reduced neurological impairment, and delayed disease development by reducing immune cell infiltration (CD4+IL-17+ and CD4+IFNγ+) into the central nervous system. Furthermore, MaR1 administration enhanced IL-10 production, primarily in macrophages and CD4+ cells. However, neutralizing IL-10 with an anti-IL-10 antibody eliminated the protective impact by MaR1 in relapsing-remitting experimental autoimmune encephalomyelitis model, implying the significance of IL-10 in MaR1 treatment. Metabolism has been recognized as a critical mediator of effector activity in many types of immune cells. In our investigation, MaR1 administration significantly repaired metabolic dysregulation in CD4+ cells, macrophages, and microglia in EAE mice. Furthermore, MaR1 treatment restored defective efferocytosis in treated macrophages and microglia. MaR1 also preserved myelin in EAE mice and regulated O4+ oligodendrocyte metabolism by reversing metabolic dysregulation via increased mitochondrial activity and decreased glycolysis. Overall, in a preclinical MS animal model, MaR1 therapy has anti-inflammatory and neuroprotective properties. It also induced metabolic reprogramming in disease-associated cell types, increased efferocytosis, and maintained myelination. Moreover, our data on patient-derived peripheral blood mononuclear cells substantiated the protective role of MaR1, expanding the therapeutic spectrum of specialized proresolving lipid mediators. Altogether, these findings suggest the potential of MaR1 as a novel therapeutic agent for MS and other autoimmune diseases.

Cytometry at the Intersection of Metabolism and Epigenetics in Lymphocyte Dynamics

Landmark studies at the turn of the century revealed metabolic reprogramming as a driving force for lymphocyte differentiation and function. In addition to metabolic changes, differentiating lymphocytes must remodel their epigenetic landscape to properly rewire their gene expression. Recent discoveries have shown that metabolic shifts can shape the fate of lymphocytes by altering their epigenetic state, bringing together these two areas of inquiry. The ongoing evolution of high-dimensional cytometry has enabled increasingly comprehensive analyses of metabolic and epigenetic landscapes in lymphocytes that transcend the technical limitations of the past. Here, we review recent insights into the interplay between metabolism and epigenetics in lymphocytes and how its dysregulation can lead to immunological dysfunction and disease. We also discuss the latest technical advances in cytometry that have enabled these discoveries and that we anticipate will advance future work in this area.

Targeting metabolic dysfunction of CD8 T cells and natural killer cells in cancer

The importance of metabolic pathways in regulating immune responses is now well established, and a mapping of the bioenergetic metabolism of different immune cell types is under way. CD8 T cells and natural killer (NK) cells contribute to cancer immunosurveillance through their cytotoxic functions and secretion of cytokines and chemokines, complementing each other in target recognition mechanisms. Several immunotherapies leverage these cell types by either stimulating their activity or redirecting their specificity against tumour cells. However, the anticancer activity of CD8 T cells and NK cells is rapidly diminished in the tumour microenvironment, closely linked to a decline in their metabolic capacities. Various strategies have been developed to restore cancer immunosurveillance, including targeting bioenergetic metabolism or genetic engineering. This Review provides an overview of metabolic dysfunction in CD8 T cells and NK cells within the tumour microenvironment, highlighting current therapies aiming to overcome these issues.

Simultaneous Application of Methylene Blue and Chlorin e6 Photosensitizers: Investigation on a Cell Culture

The application of photosensitizers for inhibition of oxidative phosphorylation in order to temporally decrease oxygen uptake by tumor cells in the course of photodynamic therapy (PDT) evokes growing interest. The aim of the study is to overcome tumor hypoxia for further photodynamic therapy with simultaneous use of type I photosensitizer methylene blue (MB) and type II photosensitizer chlorin e6.

Material and Methods

A photodynamic activity of MB and its combined use with chlorin e6 has been studied on the HeLa cell culture, their effect on cell metabolism in their co-accumulation and subsequent irradiation has also been assessed.

Results

MB generates reactive oxygen species in the cells in contrast to chlorin e6, which produces singlet oxygen. Besides, MB is converted to a colorless leucoform at low concentrations in the process of de-oxygenation. Incubation of cells with MB concurrently with chlorin e6 results in its greater fluorescence as compared to the incubation with MB only. MB concentration in the range of 1-10 mg/kg and the laser radiation dose of 60 J/cm2 do not cause cell death, probably, due to the MB transition to the photodynamically inactive leucoform. Cell death is observed after PDT in all samples with chlorin e6 and with MB at the 0-20 mg/kg concentration ranges and at 60 J/cm2 radiation dose. The phototoxicity of MB together with chlorin e6 is higher than that of chlorin e6 alone. The analysis of metabolic NADH cofactor lifetime after the incubation of the cells with MB and chlorin e6, and after PDT with them has revealed the presence of stress seen as an extension of NADH fluorescence cloud along the metabolic axis. After PDT with low concentrations of MB, the NADH fluorescent cloud on the phasor diagram shifts to the right towards short lifetimes (closer to anaerobic glycolysis along the NADH metabolic trajectory). The PDT with MB and chlorin e6 leads to the shift of the NADH fluorescence cloud on the phasor diagram to the left towards long lifetimes (closer to oxidative phosphorylation along the NADH metabolic trajectory). In this case, the cells die due to necrosis.

Conclusion

The co-accumulation of MB with chlorin e6 prevents MB reduction to a colorless leucoform, decreasing the oxygen uptake by the cells and making it possible to use simultaneously type I and II photodynamic reactions.

CD3+ T-cell: CD14+ monocyte complexes are dynamic and increased with HIV and glucose intolerance

Persistent systemic inflammation is associated with an elevated risk of cardiometabolic diseases. However, the characteristics of the innate and adaptive immune systems in individuals who develop these conditions remain poorly defined. Doublets, or cell-cell complexes, are routinely eliminated from flow cytometric and other immune phenotyping analyses, which limits our understanding of their relationship to disease states. Using well-characterized clinical cohorts, including participants with controlled human immunodeficiency virus (HIV) as a model for chronic inflammation and increased immune cell interactions, we show that circulating CD14+ monocytes complexed to CD3+ T cells are dynamic, biologically relevant, and increased in individuals with diabetes after adjusting for confounding factors. The complexes form functional immune synapses with increased expression of proinflammatory cytokines and greater glucose utilization. Furthermore, in persons with HIV, the CD3+ T cell: CD14+ monocyte complexes had more HIV copies compared to matched CD14+ monocytes or CD4+ T cells alone. Our results demonstrate that circulating CD3+ T-cell: CD14+ monocyte pairs represent dynamic cellular interactions that may contribute to inflammation and cardiometabolic disease pathogenesis. CD3+ T-cell: CD14+ monocyte complexes may originate or be maintained, in part, by chronic viral infections. These findings provide a foundation for future studies investigating mechanisms linking T cell-monocyte cell-cell complexes to developing immune-mediated diseases, including HIV and diabetes.

Differences in glycolytic metabolism between tissue-resident alveolar macrophages and recruited lung macrophages

Immunometabolism has emerged as a key area of focus in immunology and has the potential to lead to new treatments for immune-related diseases. It is well-established that glycolytic metabolism is essential for adaptation to hypoxia and for macrophage inflammatory function. Macrophages have been shown to upregulate their glycolytic metabolism in response to pathogens and pathogen-associated molecular patterns such as LPS. As a direct link to the external environment, the lungs' distinctive nutrient composition and multiple macrophage subtypes provide a unique opportunity to study macrophage metabolism. This review aims to highlight how the steady-state airway and severely inflamed airway offer divergent environments for macrophage glycolytic metabolism. We describe the differences in glycolytic metabolism between tissue-resident alveolar macrophages, and other lung macrophages at steady-state and during inflammation/injury. We also provide an overview of experimental guidelines on how to assess metabolism at the cellular level using Seahorse-based bioenergetic analysis including a review of pharmacologic agents used to inhibit or activate glycolysis.

Dual-functional co-crystal of streptavidin and ssDNA: electrostatic assembly with positively charged peptide tags

We have achieved a novel co-crystal in which the dual functions of the protein and single-stranded DNA are maintained by introducing a charged peptide tag at the C-terminus of the protein. The functionalities allowed the co-crystals to be modified with high selectivity. Additionally, we have confirmed that energy transfer occurs between the two molecules modified within the co-crystal. Therefore, this co-crystal has the potential as a novel biomaterial applicable to biosensors.

Female sex hormones and the oral contraceptive pill modulate asthma severity through GLUT-1

Females are disproportionately affected by asthma. An increased understanding of how female sex hormones influence key pathophysiological processes that underpin asthma may identify new, more effective asthma therapies, particularly for females with severe, poorly controlled asthma. We assessed the effects of oral ethinylestradiol/levonorgestrel (representing OCP use) and depot-medroxyprogesterone acetate (DMPA) and estradiol injections on key features of experimental asthma, and determined their effects on glucose transporter-1 (GLUT-1). The effects of OCP use on clinical asthma outcomes, and the relationships between estrogen receptors and type 2 (T2), non-T2, and GLUT-1 responses, in clinical asthma were also determined. OCP and DMPA reduce T2 responses, disease features, and lung expression of GLUT-1, whereas estradiol increases lung expression of GLUT-1, and results in severe, corticosteroid-insensitive, neutrophil-enriched disease, in experimental asthma. OCP use is associated with reduced T2 cytokine and GLUT-1 responses in clinical asthma. GLUT-1 expression is increased in sputum of severe asthmatics, and positively correlates with estrogen receptor expression and both T2 and non-T2 inflammatory responses. Significantly, OCP or GLUT-1 inhibition protects against obesity-associated or estradiol-induced, severe, experimental asthma, respectively. Together, these data show how female sex hormones and the OCP likely modulate asthma severity by modifying GLUT-1 responses in the airways.

Distinct metabolic profiles of circulating plasmacytoid dendritic cells in systemic sclerosis patients stratified by clinical phenotypes

BACKGROUND

Plasmacytoid dendritic cells (pDCs) play a key role in systemic sclerosis (SSc) pathophysiology. However, despite the recognised importance of metabolic reprogramming for pDC function, their metabolic profile in SSc remains to be elucidated. Thus, our study aimed to explore the metabolic profile of pDCs in SSc and their potential contribution to the disease.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from the blood of healthy donors and SSc patients. SCENITH™, a single-cell flow cytometry-based method, was applied to infer the metabolic profile of circulating pDCs from patients with SSc. pDCs (CD304+ Lin-) at steady-state or stimulated with CpG A were analysed. Toll-like receptor (TLR)9 activation was confirmed by ribosomal protein S6 phosphorylation.

RESULTS

Circulating pDCs from ten healthy donors and fourteen SSc patients were analysed. pDCs from anti-centromere antibody-positive (ACA+) patients displayed higher mitochondrial dependence and lower glycolytic capacity than those from anti-topoisomerase I antibody-positive (ATA+) patients. Furthermore, cells from both ACA+ patients and limited cutaneous SSc (lcSSc) patients showed a stronger response towards TLR9 activation than cells from ATA+, anti-RNA polymerase III antibody-positive (ARA+) or diffuse cutaneous SSc (dcSSc) patients.

CONCLUSIONS

An innovative single cell flow cytometry-based methodology was applied to analyse the metabolic profile of pDCs from SSc patients. Our results suggest that pDCs from ACA+ patients rely more on oxidative phosphorylation (OXPHOS) and are more responsive to external stimuli, whereas pDCs from ATA+ patients may exhibit a more activated or exhausted profile.

Perfluorodecanoic acid (PFDA) increases oxidative stress through inhibition of mitochondrial β-oxidation

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic organic chemicals that are ubiquitous environmental pollutants. Among PFAS, perfluorodecanoic acid (PFDA) is one of the most toxic compounds, but the molecular basis behind its toxicity is not fully understood. In an interspecies comparison with placental cells (HTR-8/SVneo) and zebrafish embryos, we demonstrate that PFDA induces mitochondrial dysfunction and impairs fatty acid β-oxidation. Reduced β-oxidation leads to less TCA cycle activity, resulting in less NADH and consequently NADPH production. Thereby NADPH-dependent glutathione recycling is impaired, increasing cellular oxidative stress that can only be partially compensated by NRF2 activation.

Genetic disruption of Blimp-1 drastically augments the antitumor efficacy of BCMA-targeting CAR T cells

ABSTRACT

Chimeric antigen receptor (CAR) T cells directed against B-cell maturation antigen (BCMA) are an effective treatment for multiple myeloma (MM), but short persistence and frequent relapses are challenges for this immunotherapy. This lack of durability has been attributed to the premature terminal differentiation of CAR T cells, which prevents the formation of long-lived memory cells that maintain antitumor responses. To improve long-term efficacy, we used CRISPR/CRISPR-associated protein 9-mediated gene editing to ablate the expression of the transcription factor Blimp-1. Blimp-1 knockout (KO) CAR T cells displayed a memory-like phenotype compared with control (Mock) CAR T cells, but had reduced effector function, with a striking loss of granzyme B. However, in a murine model of advanced MM, Blimp-1 KO CAR T cells effectively slowed or even prevented disease progression, significantly outperforming Mock CAR T cells in improving survival (P = .006). To understand this enhanced in vivo effectiveness, Blimp-1 KO CAR T cells were characterized after being repeatedly challenged with tumor cells in vitro. In this setting, Blimp-1 KO CAR T cells maintained a highly active state with high expression of memory markers, but, crucially, demonstrated enhanced effector function and increased energetic capacity. RNA-sequencing analysis of tumor-exposed Blimp-1 KO CAR T cells confirmed the presence of a memory-like transcriptomic signature and, additionally, revealed enhanced ribosome biogenesis and repressed CAR T-cell dysfunction as mechanisms that could contribute to improved antitumor activity. Put together, our findings show that dampening Blimp-1 expression altered the phenotype and function of anti-BCMA CAR T cells, leading to augmented therapeutic efficacy in MM.

Development of itaconate polymer microparticles for intracellular regulation of pro-inflammatory macrophage activation

Itaconate (IA) is an endogenous metabolite and a potent regulator of the innate immune system. Its use in immunomodulatory therapies has faced limitations due to inherent challenges in achieving controlled delivery and requirements for high extracellular concentrations to achieve internalization of the highly polar small molecule to achieve its intracellular therapeutic activity. Microparticle (MP)-based delivery strategies are a promising approach for intracellular delivery of small molecule metabolites through macrophage phagocytosis and subsequent intracellular polymer degradation-based delivery. Toward the goal of intracellular delivery of IA, degradable polyester polymer-(poly(itaconate-co-dodecanediol)) based IA polymer microparticles (IA-MPs) were generated using an emulsion method, forming micron-scale (∼ 1.5 µm) degradable microspheres. IA-MPs were characterized with respect to their material properties and IA release kinetics to inform particle fabrication. Treatment of murine bone marrow-derived macrophages with an optimized particle concentration of 0.1 mg/million cells enabled phagocytosis-mediated internalization and low levels of cytotoxicity. Flow cytometry demonstrated IA-MP-specific regulation of IA-sensitive inflammatory targets. Metabolic analyses demonstrated that IA-MP internalization inhibited oxidative metabolism and induced glycolytic reliance, consistent with the established mechanism of IA-associated inhibition of succinate dehydrogenase. This development of IA-based polymer microparticles provides a basis for additional innovative metabolite-based microparticle drug delivery systems for the treatment of inflammatory disease.

Single cell suppression profiling of human regulatory T cells

Regulatory T cells (Treg) play an important role in regulating immune homeostasis in health and disease. Traditionally their suppressive function has been assayed by mixing purified cell populations, which does not provide an accurate picture of a physiologically relevant response. To overcome this limitation, we here develop 'single cell suppression profiling of human Tregs' (scSPOT). scSPOT uses a 52-marker CyTOF panel, a cell division detection algorithm, and a whole PBMC system to assess the effect of Tregs on all other cell types simultaneously. In this head-to-head comparison, we find Tregs having the clearest suppressive effects on effector memory CD8 T cells through partial division arrest, cell cycle inhibition, and effector molecule downregulation. Additionally, scSPOT identifies a Treg phenotypic split previously observed in viral infection and propose modes of action by the FDA-approved drugs Ipilimumab and Tazemetostat. scSPOT is thus scalable, robust, widely applicable, and may be used to better understand Treg immunobiology and screen for therapeutic compounds.

mTOR/HIF-1α pathway-mediated glucose reprogramming and macrophage polarization by Sini decoction plus ginseng soup in ALF

BACKGROUND

Acute liver failure (ALF) has a high mortality rate, and despite treatment advancements, long-term outcomes remain poor.

PURPOSE

This study explores the therapeutic targets and pathways of Sini Decoction plus Ginseng Soup (SNRS) in ALF using bioinformatics and network pharmacology, focusing on its impact on macrophage polarization through glucose metabolism reprogramming. The efficacy of SNRS was validated in an LPS/D-GalN-induced ALF model, and its optimal concentration was determined for in vitro macrophage intervention.

STUDY DESIGN AND METHODS

Differentially expressed genes (DEGs) in HBV-induced and acetaminophen-induced ALF were identified from GEO datasets. The correlation between target gene expression and immune cell infiltration in ALF liver tissue was analyzed. AST, ALT, TNF-α, HMGB1, IL-1β, IL-6, and IL-10 levels were measured, and liver histopathology was assessed. Macrophage polarization was analyzed via immunofluorescence, flow cytometry, and Western blot. Glycolysis-related enzymes and metabolites, including HK2, PFK-1, PKM2, and LDHA, were quantified. Cellular ultrastructure was examined by transmission electron microscopy.

RESULTS

Five key glycolysis-regulating genes (HK2, CDK1, SOD1, VEGFA, GOT1) were identified, with significant involvement in the HIF-1 signaling pathway. Immune infiltration was markedly higher in ALF liver tissue. SNRS improved survival, reduced ALT/AST levels, alleviated liver injury, and modulated macrophage polarization by decreasing CD86 and increasing CD163 expression. In vitro, SNRS inhibited LPS-induced inflammatory cytokine release, lactate production, p-mTOR/mTOR ratio, and HIF-1α expression.

CONCLUSION

SNRS modulates macrophage polarization and glucose metabolism reprogramming via the mTOR/HIF-1α pathway, showing promise as a treatment for ALF.

The hidden impact of GLP-1 receptor agonists on endometrial receptivity and implantation

Increasing infertility rates represent a growing medical challenge in modern societies resulting from a complex interplay of sociocultural trends, lifestyle factors, exposure to environmental toxins, and underlying health problems. Women's fertility is particularly vulnerable to these shifts. The obesogenic lifestyle not only accelerates weight gain, but also disrupts ovulation driving the rise in infertility. Among several medications used for treating obesity and type 2 diabetes, glucagon-like peptide-1 receptor agonists (GLP-1RAs) show promising improvement in female fertility most likely by stimulating ovulation. However, the effects of GLP-1RAs on the endometrium remain unclear. Further studies are needed to investigate the impact of GLP-1RAs on endometrial receptivity and embryo implantation and early development. The aim of this study is to address the knowledge gap regarding the effects of GLP-1RAs on human reproduction, with special focus on the endometrium. Understanding these mechanisms may help to develop new strategies for improving fertility treatment, reduce implantation failure and address potential safety concerns regarding teratogenicity and adverse developmental outcomes for children born to women conceiving during or soon after GLP-1RA treatment.

HBV and HBsAg strongly reshape the phenotype, function, and metabolism of DCs according to patients' clinical stage

BACKGROUND

Hepatitis B is a liver infection caused by HBV. Infected individuals who fail to control the viral infection develop chronic hepatitis B and are at risk of developing life-threatening liver diseases, such as cirrhosis or liver cancer. Dendritic cells (DCs) play important roles in the immune response against HBV but are functionally impaired in patients with chronic hepatitis B. The underlying mechanisms involved in HBV-induced DC dysfunctions remain to be elucidated.

METHODS

We explored DC modulations by HBV and HBsAg by exposing blood-derived cDC1s, cDC2s, and plasmacytoid DCs from healthy donors to HBV or HBsAg and stimulating them with toll-like receptor ligand. Their phenotypic and functional features, as well as their metabolic profile, were analyzed through multiparametric flow cytometry and multiplex assays and further explored on patients' samples.

RESULTS

We found that HBV deeply reshaped the DC secretome in response to toll-like receptor ligand. Strikingly, we observed that HBV-exposed DCs secrete high levels of CX3CL1 (fractalkine), a chemokine responsible for attracting antiviral effectors to the site of infection. HBsAg exposure favored DC activation while drastically altering TRAIL expression in response to toll-like receptor ligand and increasing the secretion of cytokines/chemokines involved in immune tolerance. HBsAg further dampened the metabolism of DC subsets while driving metabolic switches. Notably, the relevance of the CX3CL1/CX3CR1 axis, TGF-β, and metabolic disturbances was demonstrated within intrahepatic DC subsets in patients according to disease stage.

CONCLUSIONS

Our work brings new insights into the immunomodulation induced by HBV on DCs, which contribute to impaired antiviral responses and progression toward chronicity.

Expanding the diagnostic toolbox for complex genetic immune disorders

Laboratory-based immunology evaluation is essential to the diagnostic workup of patients with complex immune disorders, and is as essential, if not more so, depending on the context, as genetic testing, because it enables identification of aberrant pathways amenable to therapeutic intervention and clarifies variants of uncertain significance. There have been considerable advances in techniques and instrumentation in the clinical laboratory in the past 2 decades, although there are still "miles to go." One of the goals of the clinical laboratory is to ensure advanced diagnostic testing is widely accessible to physicians and thus patients, through reference laboratories, particularly in the context of academic medical centers. This ensures a greater likelihood of translating research discoveries into the diagnostic laboratory, on the basis of patient care needs rather than a sole emphasis on commercial utility. However, these advances are under threat from burdensome regulatory oversight that can compromise, at best, and curtail, at worst, the ability to rapidly diagnose rare immune disorders and ensure delivery of precision medicine. This review discusses the clinical utility of diagnostic immunology tools, beyond cellular immunophenotyping of lymphocyte subsets, which can be used in conjunction with clinical and other laboratory data for diagnosis as well as monitoring of therapeutic response in patients with genetic immunologic diseases.

Metabolic Adaptations Rewire CD4 T Cells in a Subset-Specific Manner in Human Critical Illness with and without Sepsis

Host immunity in sepsis has features of hyperinflammation together with progressive immunosuppression, particularly among CD4 T cells, that can predispose to secondary infections and ineffectual organ recovery. Metabolic and immunologic dysfunction are archetypal findings in critically ill patients with sepsis, but whether these factors are mechanistically linked remains incompletely defined. We characterized functional metabolic properties of human CD4 T cells from critically ill patients with and without sepsis and healthy adults. CD4 T cells in critical illness showed increased subset-specific metabolic plasticity, with regulatory T cells (Tregs) acquiring glycolytic capacity that stabilized suppressive markers FOXP3 and TIGIT and correlated with clinical illness severity. Single-cell transcriptomics identified differential kynurenine metabolism in Tregs, which was validated ex vivo as a mechanism of Treg glycolytic adaptation and suppressive rewiring. These findings underscore immunometabolic dysfunction as a driver of CD4 T cell remodeling in sepsis and suggest therapeutic avenues to restore an effective immune response.

A multimodal imaging pipeline to decipher cell-specific metabolic functions and tissue microenvironment dynamics

Tissue microenvironments are extremely complex and heterogeneous. It is challenging to study metabolic interaction between the different cell types in a tissue with the techniques that are currently available. Here we describe a multimodal imaging pipeline that allows cell type identification and nanoscale tracing of stable isotope-labeled compounds. This pipeline extends upon the principles of correlative light, electron and ion microscopy, by combining confocal microscopy reporter or probe-based fluorescence, electron microscopy, stable isotope labeling and nanoscale secondary ion mass spectrometry. We apply this method to murine models of hepatocellular and mammary gland carcinomas to study uptake of glucose derived carbon (13C) and glutamine derived nitrogen (15N) by tumor-associated immune cells. In vivo labeling with fluorescent-tagged antibodies (B220, CD3, CD8a, CD68) in tandem with confocal microscopy allows for the identification of specific cell types (B cells, T cells and macrophages) in the tumor microenvironment. Subsequent image correlation with electron microscopy offers the contrast and resolution to image membranes and organelles. Nanoscale secondary ion mass spectrometry tracks the enrichment of stable isotopes within these intracellular compartments. The whole protocol described here would take ~6 weeks to perform from start to finish. Our pipeline caters to a broad spectrum of applications as it can easily be adapted to trace the uptake and utilization of any stable isotope-labeled nutrient, drug or a probe by defined cellular populations in any tissue in situ.