Immune cell metabolism in autoimmunity

FOXP3 Transcriptionally Activates Fatty Acid Scavenger Receptor CD36 in Tumour-Induced Treg Cells

The host immune system is adapted in a variety of ways by tumour microenvironment and growing tumour interacts to promote immune escape. One of these adaptations is manipulating the metabolic processes of cells in the tumour microenvironment. The growing tumour aggressively utilise glucose, its primary energy source available in tumour site, and produce lactate by Warburg effect. In such a hostile environment, tumour-infiltrating immune cells are unable to survive metabolically. Tumour-infiltrating CD4+ Treg cells, on the other hand, adapted to an alternative energy-generating system, switching from the highly-competitive glucose to the fatty-acid metabolic pathway, by down-regulating glucose-metabolising genes and up-regulating fatty-acid metabolising genes. Tregs with high-levels of the fatty acid scavenger receptor CD36, a key component of the fatty-acid metabolic pathway, aided this metabolic shift. Treg cell formation was hampered when the fatty-acid metabolic pathway was disrupted, showing that it is necessary for Treg cell development. FOXP3, the Treg lineage-specific transcription factor, regulates fatty-acid metabolism by inducing CD36 transcription. A high-fat diet enhanced Treg development while suppressing anti-tumour immunity, whereas a low-fat diet suppressed Treg development. The altered metabolism of tumour-infiltrating Treg cells enables their rapid generation and survival in the hostile tumour microenvironment, aiding cancer progression. Fascinatingly, mice fed with a low-fat diet showed a positive prognosis with chemotherapy than mice fed with a high-fat diet. Thus, a maximum efficacy of chemotherapy might be achieved by altering diet composition during chemotherapy, providing a promising indication for future cancer treatment.

Regulation of Stress-Induced Immunosuppression in the Context of Neuroendocrine, Cytokine, and Cellular Processes

Understanding the regulatory mechanisms of stress-induced immunosuppression and developing reliable diagnostic methods are important tasks in clinical medicine. This will allow for the development of effective strategies for the prevention and treatment of conditions associated with immune system dysfunction induced by chronic stress. The purpose of this review is to conduct a comprehensive analysis and synthesis of existing data on the regulatory mechanisms of stress-induced immunosuppression. The review is aimed at identifying key neuroendocrine, cytokine, and cellular processes underlying the suppression of the immune response under stress. This study involved a search of scientific literature covering the neuroendocrine, cellular, and molecular mechanisms of stress-induced immunosuppression regulation, as well as modern methods for its diagnosis. Major international bibliographic databases covering publications in biomedicine, psychophysiology, and immunology were selected for the search. The results of the analysis identified key mechanisms regulating stress-induced immunosuppression. The reviewed publications provided detailed descriptions of the neuroendocrine and cytokine processes underlying immune response suppression under stress. A significant portion of the data confirms that the activation of the hypothalamic-pituitary-adrenal (HPA) axis and subsequent elevation of cortisol levels exert substantial immunosuppressive effects on immune cells, particularly macrophages and lymphocytes, leading to the suppression of innate and adaptive immune responses. The data also highlight the crucial role of cortisol and catecholamines (adrenaline and noradrenaline) in initiating immunosuppressive mechanisms under chronic stress.

Inhibition of BCAT1-mediated cytosolic leucine metabolism regulates Th17 responses via the mTORC1-HIF1α pathway

Branched-chain amino acids (BCAAs), particularly leucine, are indispensable AAs for immune regulation through metabolic rewiring. However, the molecular mechanism underlying this phenomenon remains unclear. Our investigation revealed that T-cell receptor (TCR)-activated human CD4+ T cells increase the expression of BCAT1, a cytosolic enzyme responsible for BCAA catabolism, and SLC7A5, a major BCAA transporter. This upregulation facilitates increased leucine influx and catabolism, which are particularly crucial for Th17 responses. Activated CD4+ T cells induce an alternative pathway of cytosolic leucine catabolism, generating a pivotal metabolite, β-hydroxy β-methylbutyric acid (HMB), by acting on BCAT1 and 4-hydroxyphenylpyruvate dioxygenase (HPD)/HPD-like protein (HPDL). Inhibition of BCAT1-mediated cytosolic leucine metabolism, either with BCAT1 inhibitor 2 (Bi2) or through BCAT1, HPD, or HPDL silencing using shRNA, attenuates IL-17 production, whereas HMB supplementation abrogates this effect. Mechanistically, HMB contributes to the regulation of the mTORC1-HIF1α pathway, a major signaling pathway for IL-17 production, by increasing the mRNA expression of HIF1α. This finding was corroborated by the observation that treatment with L-β-homoleucine (LβhL), a leucine analog and competitive inhibitor of BCAT1, decreased IL-17 production by TCR-activated CD4+ T cells. In an in vivo experimental autoimmune encephalomyelitis (EAE) model, blockade of BCAT1-mediated leucine catabolism, either through a BCAT1 inhibitor or LβhL treatment, mitigated EAE severity by decreasing HIF1α expression and IL-17 production in spinal cord mononuclear cells. Our findings elucidate the role of BCAT1-mediated cytoplasmic leucine catabolism in modulating IL-17 production via HMB-mediated regulation of mTORC1-HIF1α, providing insights into its relevance to inflammatory conditions.

Single-cell and bulk RNA-sequencing analysis to predict the role and clinical value of CD36 in lung squamous cell carcinoma

The majority of patients with lung squamous cell carcinoma are diagnosed at an advanced stage, which poses a challenge to the efficacy of chemotherapy. Therefore, the search for an early biomarker needs to be addressed. CD36 is a scavenger receptor expressed in various cell types. It has been reported that it is closely related to the occurrence and development of many kinds of tumours. However, its role in lung squamous cell carcinoma has not been reported. Our research aims to reveal the role of CD36 in lung squamous cell carcinoma by integrating single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing data. We used bioinformatics methods to explore the potential carcinogenicity of CD36 by analysing the data from the cancer genome map (TCGA), gene expression comprehensive map (GEO), human protein map (HPA) comparative toxicology genomics database (CTD) and other resources. Our study dissected the relationship between CD36 and prognosis and gene correlation, functional analysis, mutation of different tumours, infiltration of immune cells and exploring the interaction between CD36 and chemicals. The results showed that the expression of CD36 was heterogeneous. Compared with normal patients, the expression was low in lung squamous cell carcinoma. In addition, CD36 showed early diagnostic value in four kinds of tumours (LUSC, BLCA, BRCA and KIRC) and was positively or negatively correlated with the prognosis of different tumours. The relationship between CD36 and the tumour immune microenvironment was revealed by immunoinfiltration analysis, and many drugs that might target CD36 were identified by the comparative toxicological genomics database (CTD). In summary, through pancancer analysis, we found and verified for the first time that CD36 may play a role in the detection of lung squamous cell carcinoma. In addition, it has high specificity and sensitivity in detecting cancer. Therefore, CD36 can be used as an auxiliary index for early tumour diagnosis and a prognostic marker for lung squamous cell carcinoma.

Mitochondrial dysfunctions in T cells: focus on inflammatory bowel disease

Mitochondria has emerged as a critical ruler of metabolic reprogramming in immune responses and inflammation. In the context of colitogenic T cells and IBD, there has been increasing research interest in the metabolic pathways of glycolysis, pyruvate oxidation, and glutaminolysis. These pathways have been shown to play a crucial role in the metabolic reprogramming of colitogenic T cells, leading to increased inflammatory cytokine production and tissue damage. In addition to metabolic reprogramming, mitochondrial dysfunction has also been implicated in the pathogenesis of IBD. Studies have shown that colitogenic T cells exhibit impaired mitochondrial respiration, elevated levels of mROS, alterations in calcium homeostasis, impaired mitochondrial biogenesis, and aberrant mitochondria-associated membrane formation. Here, we discuss our current knowledge of the metabolic reprogramming and mitochondrial dysfunctions in colitogenic T cells, as well as the potential therapeutic applications for treating IBD with evidence from animal experiments.

Metabolite Alterations in Autoimmune Diseases: A Systematic Review of Metabolomics Studies

Autoimmune diseases, characterized by the immune system's loss of self-tolerance, lack definitive diagnostic tests, necessitating the search for reliable biomarkers. This systematic review aims to identify common metabolite changes across multiple autoimmune diseases. Following PRISMA guidelines, we conducted a systematic literature review by searching MEDLINE, ScienceDirect, Google Scholar, PubMed, and Scopus (Elsevier) using keywords "Metabolomics", "Autoimmune diseases", and "Metabolic changes". Articles published in English up to March 2023 were included without a specific start date filter. Among 257 studies searched, 88 full-text articles met the inclusion criteria. The included articles were categorized based on analyzed biological fluids: 33 on serum, 21 on plasma, 15 on feces, 7 on urine, and 12 on other biological fluids. Each study presented different metabolites with indications of up-regulation or down-regulation when available. The current study's findings suggest that amino acid metabolism may serve as a diagnostic biomarker for autoimmune diseases, particularly in systemic lupus erythematosus (SLE), multiple sclerosis (MS), and Crohn's disease (CD). While other metabolic alterations were reported, it implies that autoimmune disorders trigger multi-metabolite changes rather than singular alterations. These shifts could be consequential outcomes of autoimmune disorders, representing a more complex interplay. Further studies are needed to validate the metabolomics findings associated with autoimmune diseases.

In Silico Localization of Perilymph Proteins Enriched in Meńier̀e Disease Using Mammalian Cochlear Single-cell Transcriptomics

Hypothesis

Proteins enriched in the perilymph proteome of Meńier̀e disease (MD) patients may identify affected cell types. Utilizing single-cell transcriptome datasets from the mammalian cochlea, we hypothesize that these enriched perilymph proteins can be localized to specific cochlear cell types.

Background

The limited understanding of human inner ear pathologies and their associated biomolecular variations hinder efforts to develop disease-specific diagnostics and therapeutics. Perilymph sampling and analysis is now enabling further characterization of the cochlear microenvironment. Recently, enriched inner ear protein expression has been demonstrated in patients with MD compared to patients with other inner ear diseases. Localizing expression of these proteins to cochlear cell types can further our knowledge of potential disease pathways and subsequent development of targeted therapeutics.

Methods

We compiled previously published data regarding differential perilymph proteome profiles amongst patients with MD, otosclerosis, enlarged vestibular aqueduct, sudden hearing loss, and hearing loss of undefined etiology (controls). Enriched proteins in MD were cross-referenced against published single-cell/single-nucleus RNA-sequencing datasets to localize gene expression to specific cochlear cell types.

Results

In silico analysis of single-cell transcriptomic datasets demonstrates enrichment of a unique group of perilymph proteins associated with MD in a variety of intracochlear cells, and some exogeneous hematologic and immune effector cells. This suggests that these cell types may play an important role in the pathology associated with late MD, suggesting potential future areas of investigation for MD pathophysiology and treatment.

Conclusions

Perilymph proteins enriched in MD are expressed by specific cochlear cell types based on in silico localization, potentially facilitating development of disease-specific diagnostic markers and therapeutics.

IL-21, Inflammatory Cytokines and Hyperpolarized CD8+ T Cells Are Central Players in Lupus Immune Pathology

Systemic lupus erythematous (SLE) is a chronic autoimmune disorder, broadly characterized by systemic inflammation along with heterogeneous clinical manifestations, severe morbidity, moribund organ failure and eventual mortality. In our study, SLE patients displayed a higher percentage of activated, inflamed and hyper-polarized CD8⁺ T cells, dysregulated CD8⁺ T cell differentiation, significantly elevated serum inflammatory cytokines and higher accumulation of cellular ROS when compared to healthy controls. Importantly, these hyper-inflammatory/hyper-polarized CD8⁺ T cells responded better to an antioxidant than to an oxidant. Terminally differentiated Tc1 cells also showed plasticity upon oxidant/antioxidant treatment, but that was in contrast to the SLE CD8⁺ T cell response. Our studies suggest that the differential phenotype and redox response of SLE CD8⁺ T cells and Tc1 cells could be attributed to their cytokine environs during their respective differentiation and eventual activation environs. The polarization of Tc1 cells with IL-21 drove hyper-cytotoxicity without hyper-polarisation suggesting that the SLE inflammatory cytokine environment could drive the extreme aberrancy in SLE CD8⁺ T cells.

Therapeutic nexus of T cell immunometabolism in improving transplantation immunotherapy

Immunometabolism is a therapeutic strategy to tune immune cells through metabolic reprogramming, which allows immune cells to be differentiated according to their energy requirements. Recent therapeutic strategies targeting immunometabolism suggest that intracellular metabolic reprogramming controls T cell activation, proliferation, and differentiation into effector (Teff) or regulatory (Treg) cells. Immunometabolism is being studied for the treatment of inflammatory diseases, including those associated with solid organ transplantation (SOT). Here, we review immunometabolic regulation of immune cells, with a particular focus on Treg metabolic regulation and liver kinase B1 (LKB1) signaling, which stabilize Tregs and prevent inflammation-associated tissue injuries. All in all, here we discussed how targeting T cell immunometabolism modulates Teff and Treg-mediated immune responses, which can be used to boost Treg differentiation, stability, and ultimately favor immunotolerance in clinical transplants.

The glucose transporter GLUT3 controls T helper 17 cell responses through glycolytic-epigenetic reprogramming

Metabolic reprogramming is a hallmark of activated T cells. The switch from oxidative phosphorylation to aerobic glycolysis provides energy and intermediary metabolites for the biosynthesis of macromolecules to support clonal expansion and effector function. Here, we show that glycolytic reprogramming additionally controls inflammatory gene expression via epigenetic remodeling. We found that the glucose transporter GLUT3 is essential for the effector functions of Th17 cells in models of autoimmune colitis and encephalomyelitis. At the molecular level, we show that GLUT3-dependent glucose uptake controls a metabolic-transcriptional circuit that regulates the pathogenicity of Th17 cells. Metabolomic, epigenetic, and transcriptomic analyses linked GLUT3 to mitochondrial glucose oxidation and ACLY-dependent acetyl-CoA generation as a rate-limiting step in the epigenetic regulation of inflammatory gene expression. Our findings are also important from a translational perspective because inhibiting GLUT3-dependent acetyl-CoA generation is a promising metabolic checkpoint to mitigate Th17-cell-mediated inflammatory diseases.

T cell metabolism and possible therapeutic targets in systemic lupus erythematosus: a narrative review

In the immunopathogenesis of systemic lupus erythematosus (SLE), there is a dysregulation of specific immune cells, including T cells. The metabolic reprogramming in T cells causes different effects. Metabolic programs are critical checkpoints in immune responses and are involved in the etiology of autoimmune disease. For instance, resting lymphocytes generate energy through oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO), whereas activated lymphocytes rapidly shift to the glycolytic pathway. Specifically, mitochondrial dysfunction, oxidative stress, abnormal metabolism (including glucose, lipid, and amino acid metabolism), and mTOR signaling are hallmarks of T lymphocyte metabolic dysfunction in SLE. Herein it is summarized how metabolic defects contribute to T cell responses in SLE, and some epigenetic alterations involved in the disease. Finally, it is shown how metabolic defects could be modified therapeutically.

Modulation of the cell membrane lipid milieu by peroxisomal β-oxidation induces Rho1 signaling to trigger inflammatory responses

Phagocytosis, signal transduction, and inflammatory responses require changes in lipid metabolism. Peroxisomes have key roles in fatty acid homeostasis and in regulating immune function. We find that Drosophila macrophages lacking peroxisomes have perturbed lipid profiles, which reduce host survival after infection. Using lipidomic, transcriptomic, and genetic screens, we determine that peroxisomes contribute to the cell membrane glycerophospholipid composition necessary to induce Rho1-dependent signals, which drive cytoskeletal remodeling during macrophage activation. Loss of peroxisome function increases membrane phosphatidic acid (PA) and recruits RhoGAPp190 during infection, inhibiting Rho1-mediated responses. Peroxisome-glycerophospholipid-Rho1 signaling also controls cytoskeleton remodeling in mouse immune cells. While high levels of PA in cells without peroxisomes inhibit inflammatory phenotypes, large numbers of peroxisomes and low amounts of cell membrane PA are features of immune cells from patients with inflammatory Kawasaki disease and juvenile idiopathic arthritis. Our findings reveal potential metabolic markers and therapeutic targets for immune diseases and metabolic disorders.

Insufficient Iron Improves Pristane-Induced Lupus by Promoting Treg Cell Expansion

Trace element iron affects T cell biology, but the knowledge about the role of iron in regulating Treg cell expansion is limited. Treg cells play an important role in keeping peripheral T cell tolerance, increasing Treg cell expansion is a promising therapeutic method for SLE. Here we showed that iron deficiency promotes Treg cell expansion by reducing ROS accumulation, improving the disease progression of pristane-induced lupus. Increased oxidative stress inhibits Treg cell differentiation by inducing cell apoptosis. Our data suggest that altering iron metabolism promotes Treg cell expansion by preventing oxidation-induced cell death, which may provide a potential therapeutic strategy for SLE.

Immunometabolism at the service of traditional Chinese medicine

To enhance therapeutic efficacy and reduce adverse effects, ancient practitioners of traditional Chinese medicine (TCM) prescribe combinations of plant species/animal species and minerals designated "TCM formulae" developed based on TCM theory and clinical experience. TCM formulae have been shown to exert curative effects on complex diseases via immune regulation but the underlying mechanisms remain unknown at present. Considerable progress in the field of immunometabolism, referring to alterations in the intracellular metabolism of immune cells that regulate their function, has been made over the past decade. The core context of immunometabolism is regulation of the allocation of metabolic resources supporting host defense and survival, which provides a critical additional dimension and emerging insights into how the immune system and metabolism influence each other during disease progression. This review summarizes research findings on the significant association between the immune function and metabolic remodeling in health and disease as well as the therapeutic modulatory effects of TCM formulae on immunometabolism. Progressive elucidation of the immunometabolic mechanisms involved during the course of TCM treatment continues to aid in the identification of novel potential targets against pathogenicity. In this report, we have provided a comprehensive overview of the benefits of TCM based on regulation of immunometabolism that are potentially applicable for the treatment of modern diseases.

Carbohydrate and lipid metabolism in multiple sclerosis: Clinical implications for etiology, pathogenesis, diagnosis, prognosis, and therapy

Multiple sclerosis (MS) is a complicated autoimmune disease characterized by inflammatory and demyelinating events in the central nervous system. The exact etiology and pathogenesis of MS have not been elucidated. However, a set of metabolic changes and their effects on immune cells and neural functions have been explained. This review highlights the contribution of carbohydrates and lipids metabolism to the etiology and pathogenesis of MS. Then, we have proposed a hypothetical relationship between such metabolic changes and the immune system in patients with MS. Finally, the potential clinical implications of these metabolic changes in diagnosis, prognosis, and discovering therapeutic targets have been discussed. It is concluded that research on the pathophysiological alterations of carbohydrate and lipid metabolism may be a potential strategy for paving the way toward MS treatment.

Altered Metabolic Phenotype of Immune Cells in a Spontaneous Autoimmune Uveitis Model

As one of the leading causes of blindness worldwide, uveitis is an important disease. The exact pathogenesis of autoimmune uveitis is not entirely elucidated to date. Equine recurrent uveitis (ERU) represents the only spontaneous animal model for autoimmune uveitis in humans. As the metabolism of immune cells is an emerging field in research and gains more and more significance to take part in the pathogenesis of various diseases, we conducted experiments to investigate the metabolism of immune cells of ERU cases and healthy controls. To our knowledge, the link between a deviant immunometabolism and the pathogenesis of autoimmune uveitis was not investigated so far. We showed that PBMC of ERU cases had a more active metabolic phenotype in basal state by upregulating both the oxidative phosphorylation and the glycolytic pathway. We further revealed an increased compensatory glycolytic rate of PBMC and CD4⁺ T cells of ERU cases under mitochondrial stress conditions. These findings are in line with metabolic alterations of immune cells in other autoimmune diseases and basic research, where it was shown that activated immune cells have an increased need of energy and molecule demand for their effector function. We demonstrated a clear difference in the metabolic phenotypes of PBMC and, more specifically, CD4⁺ T cells of ERU cases and controls. These findings are another important step in understanding the pathogenesis of ERU and figuratively, human autoimmune uveitis.

Oxidative Stress in SLE T Cells, Is NRF2 Really the Target to Treat?

Oxidative stress is a major component of cellular damage in T cells from patients with systemic lupus erythematosus (SLE) resulting amongst others in the generation of pathogenic Th17 cells. The NRF2/Keap1 pathway is the most important antioxidant system protecting cells from damage due to oxidative stress. Activation of NRF2 therefore seems to represent a putative therapeutic target in SLE, which is nevertheless challenged by several findings suggesting tissue and cell specific differences in the effect of NRF2 expression. This review focusses on the current understanding of oxidative stress in SLE T cells and its pathophysiologic and therapeutic implications.

Lipid Metabolism in Tumor-Associated Natural Killer Cells

Accumulative data demonstrate that during the initiation and progression of tumors, several types of cellular components in tumor microenvironment, including tumor cells and immune cells, exhibit malfunctions in cellular energy metabolism. For instance, lipid metabolism impairments in immune cells are crucial in coordinating immunosuppression and tumor immune escape. In particular, excessive lipids have been shown to exhibit negative effects on innate immunity. Previous studies on lipid metabolism in immune cells are mainly focused on macrophages and T lymphocytes. Although natural killer (NK) cells are major players in the innate elimination of virus, bacteria, and tumor cells, available literature reports related with lipid metabolism in NK cells and tumor-associated NK (TANK) cells are very sparse. Despite these, the importance and clinical relevance of the crosstalk among lipid metabolism, NK/TANK cells, and tumors have been clearly indicated. In this chapter, following a general description of NK and TANK cells, our knowledge on the regulation of lipid metabolism in NK cells is reviewed, with an emphasis on the roles of mTOR and SREBP signaling. Then the interactions between lipid metabolism and NK/TANK cells under pathological conditions, e.g., obesity and cancer, were carefully introduced. As there is an urgent need to reveal more regulators and to clarify detailed molecular mechanisms by which lipid metabolism interacts with NK/TANK cells, several categories of potential regulators/pathways, as well as the challenges and perspectives in this emerging field, are discussed.

The multifaceted functional role of DNA methylation in immune-mediated rheumatic diseases

Genomic predisposition cannot explain the onset of complex diseases, as well illustrated by the largely incomplete concordance among monozygotic twins. Epigenetic mechanisms, including DNA methylation, chromatin remodelling and non-coding RNA, are considered to be the link between environmental stimuli and disease onset on a permissive genetic background in autoimmune and chronic inflammatory diseases. The paradigmatic cases of rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), Sjogren's syndrome (SjS) and type-1 diabetes (T1D) share the loss of immunological tolerance to self-antigen influenced by several factors, with a largely incomplete role of individual genomic susceptibility. The most widely investigated epigenetic mechanism is DNA methylation which is associated with gene silencing and is due to the binding of methyl-CpG binding domain (MBD)-containing proteins, such as MECP2, to 5-methylcytosine (5mC). Indeed, a causal relationship occurs between DNA methylation and transcription factors occupancy and recruitment at specific genomic locus. In most cases, the results obtained in different studies are controversial in terms of DNA methylation comparison while fascinating evidence comes from the comparison of the epigenome in clinically discordant monozygotic twins. In this manuscript, we will review the mechanisms of epigenetics and DNA methylation changes in specific immune-mediated rheumatic diseases to highlight remaining unmet needs and to identify possible shared mechanisms beyond different tissue involvements with common therapeutic opportunities. Key Points • DNA methylation has a crucial role in regulating and tuning the immune system. • Evidences suggest that dysregulation of DNA methylation is pivotal in the context of immune-mediated rheumatic diseases. • DNA methylation dysregulation in FOXP3 and interferons-related genes is shared within several autoimmune diseases. • DNA methylation is an attractive marker for diagnosis and therapy.

Proteomic analysis in lupus mice identifies Coronin-1A as a potential biomarker for lupus nephritis

BACKGROUND

Approximately 50% of systemic lupus erythematosus (SLE) patients develop nephritis, which is among the most severe and frequent complications of the disease and a leading cause of morbidity and mortality. Despite intensive research, there are still no reliable lupus nephritis (LN) markers in clinical use that can assess renal damage and activity with a high sensitivity and specificity. To this end, the aim of this study was to identify new clinically relevant tissue-specific protein biomarkers and possible underlying molecular mechanisms associated with renal involvement in SLE, using mass spectrometry (MS)-based proteomics.

METHODS

Kidneys were harvested from female triple congenic B6.NZMsle1/sle2/sle3 lupus mice model, and the respective sex- and age-matched C57BL/6 control mice at 12, 24 and 36 weeks of age, representing pre-symptomatic, established and end-stage LN, respectively. Proteins were extracted from kidneys, purified, reduced, alkylated and digested by trypsin. Purified peptides were separated by liquid chromatography and analysed by high-resolution MS. Data were processed by the Progenesis QIp software, and functional annotation analysis was performed using DAVID bioinformatics resources. Immunofluorescence and multiple reaction monitoring (MRM) MS methods were used to confirm prospective biomarkers in SLE mouse strains as well as human serum samples.

RESULTS

Proteomic profiling of kidney tissues from SLE and control mice resulted in the identification of more than 3800 unique proteins. Pathway analysis revealed a number of dysregulated molecular pathways that may be mechanistically involved in renal pathology, including phagosome and proximal tubule bicarbonate reclamation pathways. Proteomic analysis supported by human transcriptomic data and pathway analysis revealed Coronin-1A, Ubiquitin-like protein ISG15, and Rho GDP-dissociation inhibitor 2, as potential LN biomarkers. These results were further validated in other SLE mouse strains using MRM-MS. Most importantly, experiments in humans showed that measurement of Coronin-1A in human sera using MRM-MS can segregate LN patients from SLE patients without nephritis with a high sensitivity (100%) and specificity (100%).

CONCLUSIONS

These preliminary findings suggest that serum Coronin-1A may serve as a promising non-invasive biomarker for LN and, upon validation in larger cohorts, may be employed in the future as a screening test for renal disease in SLE patients.

Safety and efficacy of metformin in systemic lupus erythematosus: a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND

Immunometabolism is involved in the pathogenesis of systemic lupus erythematosus (SLE). The aim of this study was to repurpose metformin, an anti-diabetic drug that regulates systemic and cellular metabolism, and assess its effects in Chinese patients with SLE without diabetes.

METHODS

We did a multicentre, randomised, double-blind, placebo-controlled trial in three hospitals in Shanghai, China. We enrolled adult patients with SLE, without diabetes, who had Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) scores no higher than 6; with no A score or no more than one B score on the British Isles Lupus Assessment Group (BILAG) scale at screening; who had had at least one lupus flare; and were treated with prednisone (≥20 mg per day) within the preceding 12 months. Patients were randomly assigned (1:1) in blocks of four by a computer algorithm to add metformin tablets (250 mg per tablet with a target dose of 0·5 g three times per day; metformin group) or placebo tablets (placebo group) to their standard therapy, for a maximum of 12 months. Patients, assessment staff, and statisticians were masked to group assignment. The primary endpoint was a composite index of major or mild-to-moderate disease flares (SELENA-SLEDAI Flare Index) at 12 months. The full analyses were done in all patients who received at least one dose of the study drug using the χ2 test. Adverse events were recorded during the 12-month follow-up. This study is registered with ClinicalTrials.gov, NCT02741960.

FINDINGS

Between May 24, 2016, and Dec 13, 2017, 180 patients were screened, of whom 140 (78%) of them were enrolled. 31 (17%) did not meet the inclusion criteria and nine (5%) withdrew informed consent without treatment after randomisation. 67 patients were assigned to the metformin group and 73 to the placebo group. By 12 months of follow-up, there was no significant difference in the incidence of lupus flares, which occurred in 14 (21%) patients in the metformin group versus 25 (34%) in the placebo group (relative risk 0·68, 0·42-1·04, p=0·078). Patients receiving metformin experienced more gastrointestinal adverse events (three [4%] discontinued for this reason vs one [1%] for placebo; overall 26 [39%] vs 11 [15%], p=0·0015), but the incidence of non-flare serious adverse events was similar between groups (one [1%] vs three [4%], p=0·35). The frequency of infection events was significantly lower in patients in the metformin group than in the placebo group (17 [25%] vs 32 [44%], p=0·022). No patients died as a result of treatment.

INTERPRETATION

This trial was underpowered to draw a sound conclusion on the efficacy of metformin to reduce disease flares as an add-on treatment to standard care in patients with SLE. Nonetheless, metformin had a favourable safety profile and our data present a basis for larger trials to investigate its potential effect on reducing the frequency of flares for patients with SLE with low-grade disease activity who are at risk of relapse.

FUNDING

Shanghai Shenkang Promoting Project and the National Key Research and Development Program of China.

Regulation of B-cell function by NF-kappaB c-Rel in health and disease

B cells mediate humoral immune response and contribute to the regulation of cellular immune response. Members of the Nuclear Factor kappaB (NF-κB) family of transcription factors play a major role in regulating B-cell functions. NF-κB subunit c-Rel is predominantly expressed in lymphocytes, and in B cells, it is required for survival, proliferation, and antibody production. Dysregulation of c-Rel expression and activation alters B-cell homeostasis and is associated with B-cell lymphomas and autoimmune pathologies. Based on its essential roles, c-Rel may serve as a potential prognostic and therapeutic target. This review summarizes the current understanding of the multifaceted role of c-Rel in B cells and B-cell diseases.

Energy metabolism manipulates the fate and function of tumour myeloid-derived suppressor cells

In recent years, a large number of studies have been carried out in the field of immune metabolism, highlighting the role of metabolic energy reprogramming in altering the function of immune cells. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells generated during a large array of pathological conditions, such as cancer, inflammation, and infection, and show remarkable ability to suppress T-cell responses. These cells can also change their metabolic pathways in response to various pathogen-derived or inflammatory signals. In this review, we focus on the roles of glucose, fatty acid (FA), and amino acid (AA) metabolism in the differentiation and function of MDSCs in the tumour microenvironment, highlighting their potential as targets to inhibit tumour growth and enhance tumour immune surveillance by the host. We further highlight the remaining gaps in knowledge concerning the mechanisms determining the plasticity of MDSCs in different environments and their specific responses in the tumour environment. Therefore, this review should motivate further research in the field of metabolomics to identify the metabolic pathways driving the enhancement of MDSCs in order to effectively target their ability to promote tumour development and progression.