Obesity Drives Th17 Cell Differentiation by Inducing the Lipid Metabolic Kinase, ACC1

M6A modification and T cells in adipose tissue inflammation

Adipose tissue in the obese state can lead to low-grade chronic inflammation while inducing or exacerbating obesity-related metabolic diseases and impairing overall health.T cells, which are essential immune cells similar to macrophages, are widely distributed in adipose tissue and perform their immunomodulatory function; they also cross-talk with other cells in the vascular stromal fraction. Based on a large number of studies, it has been found that N6 methyl adenine (m6A) is one of the most representative of epigenetic modifications, which affects the crosstalk between T cells, as well as other immune cells, in several ways and plays an important role in the development of adipose tissue inflammation and related metabolic diseases. In this review, we first provide an overview of the widespread presence of T cells in adipose tissue and summarize the key role of T cells in adipose tissue inflammation. Next, we explored the effects of m6A modifications on T cells in adipose tissue from the perspective of adipose tissue inflammation. Finally, we discuss the impact of m6a-regulated crosstalk between T cells and immune cells on the prospects for improving adipose tissue inflammation research, providing additional new ideas for the treatment of obesity.

The integration of metabolic and proteomic data uncovers an augmentation of the sphingolipid biosynthesis pathway during T-cell differentiation

Recent studies have highlighted the significance of cellular metabolism in the initiation of clonal expansion and effector differentiation of T cells. Upon exposure to antigens, naïve CD4+ T cells undergo metabolic reprogramming to meet their metabolic requirements. However, only few studies have simultaneously evaluated the changes in protein and metabolite levels during T cell differentiation. Our research seeks to fill the gap by conducting a comprehensive analysis of changes in levels of metabolites, including sugars, amino acids, intermediates of the TCA cycle, fatty acids, and lipids. By integrating metabolomics and proteomics data, we discovered that the quantity and composition of cellular lipids underwent significant changes in different effector Th cell subsets. Especially, we found that the sphingolipid biosynthesis pathway was commonly activated in Th1, Th2, Th17, and iTreg cells and that inhibition of this pathway led to the suppression of Th17 and iTreg cells differentiation. Additionally, we discovered that Th17 and iTreg cells enhance glycosphingolipid metabolism, and inhibition of this pathway also results in the suppression of Th17 and iTreg cell generation. These findings demonstrate that the utility of our combined metabolomics and proteomics analysis in furthering the understanding of metabolic transition during Th cell differentiation.

MiR-24-3p enhances the Treg/Th17 balance to improve cerebral ischemic injury by suppressing acetyl-CoA carboxylase 1 expression

BACKGROUND

Targeting ACC1 (acetyl coenzyme A carboxylase 1) to restore the balance between T-helper 17 (Th17) cells and regulatory T cells (Tregs) through metabolic reprogramming has emerged as a promising strategy for reducing neuroinflammation following stroke. We examined the roles of potential miRNAs in regulating ACC1 expression in Tregs and treating ischemic stroke.

METHODS

The expression of miR-24-3p in CD4+T cells of mice was confirmed. Then the protective effects of Ago-24-3p in a mouse model of prolonged occlusion of the distal middle cerebral artery (dMCAO) were examined. We analyzed the infiltration of Tregs and CD3+T cells into the brain and evaluated the improvement of neurological deficits induced by Ago-24-3p using the Modified Garcia Score and foot fault testing.

RESULTS

Our investigation revealed that miR-24-3p specifically targets ACC1. Elevated levels of miR-24-3p have been demonstrated to increase the population of Tregs and enhance their proliferation and suppressive capabilities. Conversely, targeted reduction of ACC1 in CD4+T cells has been shown to counteract the improved functionality of Tregs induced by miR-24-3p. In a murine model of dMCAO, administration of Ago-24-3p resulted in a substantial reduction in the size of the infarct within the ischemic brain area. This effect was accompanied by an upregulation of Tregs and a downregulation of CD3+T cells in the ischemic brain region. In ACC1 conditional knockout mice, the ability of Ago-24-3p to enhance infiltrating Treg cells and diminish CD3+T cells in the ischemic brain area has been negated. Furthermore, its capacity to reduce infarct volume has been reversed. Furthermore, we demonstrated that Ago-24-3p sustained improvement in post-stroke neurological deficits for up to 4 weeks after the MCAO procedure.

CONCLUSIONS

MiR-24-3p shows promise in the potential to reduce ACC1 expression, enhance the immunosuppressive activity of Tregs, and alleviate injuries caused by ischemic stroke. These discoveries imply that miR-24-3p could be a valuable therapeutic option for treating ischemic stroke.

The role of γδT lymphocytes in atherosclerosis

Atherosclerosis poses a significant threat to human health, impacting overall well-being and imposing substantial financial burdens. Current treatment strategies mainly focus on managing low-density lipids (LDL) and optimizing liver functions. However, it's crucial to recognize that Atherosclerosis involves more than just lipid accumulation; it entails a complex interplay of immune responses. Research highlights the pivotal role of lipid-laden macrophages in the formation of atherosclerotic plaques. These macrophages attract lymphocytes like CD4 and CD8 to the inflamed site, potentially intensifying the inflammatory response. γδ T lymphocytes, with their diverse functions in innate and adaptive immune responses, pathogen defense, antigen presentation, and inflammation regulation, have been implicated in the early stages of Atherosclerosis. However, our understanding of the roles of γδ T cells in Atherosclerosis remains limited. This mini-review aims to shed light on the characteristics and functions of γδ T cells in Atherosclerosis. By gaining insights into the roles of γδ T cells, we may uncover a promising strategy to mitigate plaque buildup and dampen the inflammatory response, thereby opening new avenues for effectively managing this condition.

Sphingolipid biosynthesis is essential for metabolic rewiring during TH17 cell differentiation

T helper 17 (TH17) cells are implicated in autoimmune diseases, and several metabolic processes are shown to be important for their development and function. In this study, we report an essential role for sphingolipids synthesized through the de novo pathway in TH17 cell development. Deficiency of SPTLC1, a major subunit of serine palmitoyl transferase enzyme complex that catalyzes the first and rate-limiting step of de novo sphingolipid synthesis, impaired glycolysis in differentiating TH17 cells by increasing intracellular reactive oxygen species (ROS) through enhancement of nicotinamide adenine dinucleotide phosphate oxidase 2 activity. Increased ROS leads to impaired activation of mammalian target of rapamycin C1 and reduced expression of hypoxia-inducible factor 1-alpha and c-Myc-induced glycolytic genes. SPTLCI deficiency protected mice from developing experimental autoimmune encephalomyelitis and experimental T cell transfer colitis. Our results thus show a critical role for de novo sphingolipid biosynthetic pathway in shaping adaptive immune responses with implications in autoimmune diseases.

Oleic acid triggers metabolic rewiring of T cells poising them for T helper 9 differentiation

T cells are the most common immune cells in atherosclerotic plaques, and the function of T cells can be altered by fatty acids. Here, we show that pre-exposure of CD4+ T cells to oleic acid, an abundant fatty acid linked to cardiovascular events, upregulates core metabolic pathways and promotes differentiation into interleukin-9 (IL-9)-producing cells upon activation. RNA sequencing of non-activated T cells reveals that oleic acid upregulates genes encoding key enzymes responsible for cholesterol and fatty acid biosynthesis. Transcription footprint analysis links these expression changes to the differentiation toward TH9 cells, a pro-atherogenic subset. Spectral flow cytometry shows that pre-exposure to oleic acid results in a skew toward IL-9+-producing T cells upon activation. Importantly, pharmacological inhibition of either cholesterol or fatty acid biosynthesis abolishes this effect, suggesting a beneficial role for statins beyond cholesterol lowering. Taken together, oleic acid may affect inflammatory diseases like atherosclerosis by rewiring T cell metabolism.

Cancer immunometabolism: advent, challenges, and perspective

For decades, great strides have been made in the field of immunometabolism. A plethora of evidence ranging from basic mechanisms to clinical transformation has gradually embarked on immunometabolism to the center stage of innate and adaptive immunomodulation. Given this, we focus on changes in immunometabolism, a converging series of biochemical events that alters immune cell function, propose the immune roles played by diversified metabolic derivatives and enzymes, emphasize the key metabolism-related checkpoints in distinct immune cell types, and discuss the ongoing and upcoming realities of clinical treatment. It is expected that future research will reduce the current limitations of immunotherapy and provide a positive hand in immune responses to exert a broader therapeutic role.

Identification and pre-clinical investigation of 3-O-cyclohexanecarbonyl-11-keto-β-boswellic acid as a drug for external use to treat psoriasis

BACKGROUND AND PURPOSE

Psoriasis vulgaris is a refractory skin inflammatory disorder with 80% of the cases belonging to the mild-to-moderate type, which can be controlled by topical treatment. Nevertheless, the drugs for external use have not been upgraded for decades. We modified acetyl-11-keto-beta-boswellic acid (ABKA), a natural compound shown to treat psoriasis animal models, to improve efficacy and solubility for topical use.

EXPERIMENTAL APPROACH

Eleven compounds were synthesized using AKBA as a lead compound, and their effects on Th17 cell differentiation were screened. 3-O-cyclohexanecarbonyl-11-keto-β-boswellic acid (CKBA) potently inhibited Th17 cell differentiation. Its efficacy in a mouse model of psoriasis was assessed along with its pharmacology and safety profile when topically or systemically delivered to several animal species.

KEY RESULTS

CKBA inhibited mouse and human Th17 cell differentiation with an IC50 of 3.28 and 3.61 μM, respectively, and directly targeted acetyl-CoA carboxylase 1 (ACC1). Safety evaluation and toxicity tests suggested that systemically delivered high-dose CKBA for 14 days had no dose-associated adverse effects on the CNS, haematopoietic, cardiovascular, respiratory and digestive systems of cynomolgus monkeys. CKBA ointment permeated the skin and did not irritate or sensitize intact skin. CKBA ointment mediated dose-dependent suppression of imiquimod-induced psoriasis-like skin inflammation with slow absorption and limited bioavailability (<10% in rats and <1% in minipigs).

CONCLUSIONS AND IMPLICATIONS

CKBA is safe when topically or systemically delivered to animals. The beneficial effects of CKBA ointment in a mouse model of psoriasis indicate that this is a promising drug candidate for further development as a treatment for psoriasis.

Metabolic Dysregulation and Its Role in Postoperative Pain among Knee Osteoarthritis Patients

Knee osteoarthritis (KOA) is characterized by low-grade inflammation, loss of articular cartilage, subchondral bone remodeling, synovitis, osteophyte formation, and pain. Strong, continuous pain may indicate the need for joint replacement in patients with end-stage OA, although postoperative pain (POP) of at least a two-month duration persists in 10-40% of patients with OA.

STUDY PURPOSE

The inflammation observed in joint tissues is linked to pain caused by the production of proinflammatory cytokines. Since the biosynthesis of cytokines requires energy, their production is supported by extensive metabolic conversions of carbohydrates and fatty acids, which could lead to a disruption in cellular homeostasis. Therefore, this study aimed to investigate the association between POP development and disturbances in energy metabolic conversions, focusing on carbohydrate and fatty acid metabolism.

METHODS

Peripheral blood samples were collected from 26 healthy subjects and 50 patients with end-stage OA before joint replacement surgery. All implants were validated by orthopedic surgeons, and patients with OA demonstrated no inherent abnormalities to cause pain from other reasons than OA disease, such as malalignment, aseptic loosening, or excessive bleeding. Pain levels were assessed before surgery using the visual analogue scale (VAS) and neuropathic pain questionnaires, DN4 and PainDETECT. Functional activity was evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Three and six months after surgery, pain indices according to a VAS of 30 mm or higher were considered. Total RNA isolated from whole blood was analyzed using quantitative real-time RT-PCR (qRT-PCR) for the expression of genes related to carbohydrate and fatty acid metabolism. Protein levels of the examined genes were measured using an ELISA in the peripheral blood mononuclear cells (PBMCs). We used qRT-PCR because it is the most sensitive and reliable method for gene expression analysis, while an ELISA was used to confirm our qRT-PCR results.

KEY FINDINGS

Among the study cohort, 17 patients who reported POP demonstrated significantly higher (p < 0.05) expressions of the genes PKM2, LDH, SDH, UCP2, CPT1A, and ACLY compared to pain-free patients with KOA. Receiver-operating characteristic (ROC) curve analyses confirmed the association between these gene expressions and pain development post-arthroplasty. A principle component analysis identified the prognostic values of ACLY, CPT1A, AMPK, SDHB, Caspase 3, and IL-1β gene expressions for POP development in the examined subjects.

CONCLUSION

These findings suggest that the disturbances in energy metabolism, as observed in the PBMCs of patients with end-stage KOA before arthroplasty, may contribute to POP development. An understanding of these metabolic processes could provide insights into the pathogenesis of KOA. Additionally, our findings can be used in a clinical setting to predict POP development in end-stage patients with KOA before arthroplasty.

Th17 cells: A new target in kidney disease research

Type 17 T helper (Th17) cells, which are a subtype of CD4+ T helper cells, secrete pro-inflammatory cytokines such as IL-17A, IL-17F, IL-21, IL-22, and GM-CSF, which play crucial roles in immune defence and protection against fungal and extracellular pathogen invasion. However, dysfunction of Th17 cell immunity mediates inflammatory responses and exacerbates tissue damage. This pathological process initiated by Th17 cells is common in kidney diseases associated with renal injury, such as glomerulonephritis, lupus nephritis, IgA nephropathy, hypertensive nephropathy, diabetic kidney disease and acute kidney injury. Therefore, targeting Th17 cells to treat kidney diseases has been a hot topic in recent years. This article reviews the mechanisms of Th17 cell-mediated inflammation and autoimmune responses in kidney diseases and discusses the related clinical drugs that modulate Th17 cell fate in kidney disease treatment.

Emerging mechanisms of obesity-associated immune dysfunction

Obesity is associated with a wide range of complications, including type 2 diabetes mellitus, cardiovascular disease, hypertension and nonalcoholic fatty liver disease. Obesity also increases the incidence and progression of cancers, autoimmunity and infections, as well as lowering vaccine responsiveness. A unifying concept across these differing diseases is dysregulated immunity, particularly inflammation, in response to metabolic overload. Herein, we review emerging mechanisms by which obesity drives inflammation and autoimmunity, as well as impairing tumour immunosurveillance and the response to infections. Among these mechanisms are obesity-associated changes in the hormones that regulate immune cell metabolism and function and drive inflammation. The cargo of extracellular vesicles derived from adipose tissue, which controls cytokine secretion from immune cells, is also dysregulated in obesity, in addition to impairments in fatty acid metabolism related to inflammation. Furthermore, an imbalance exists in obesity in the biosynthesis and levels of polyunsaturated fatty acid-derived oxylipins, which control a range of outcomes related to inflammation, such as immune cell chemotaxis and cytokine production. Finally, there is a need to investigate how obesity influences immunity using innovative model systems that account for the heterogeneous nature of obesity in the human population.

Obesity alters immunopathology in cancers and inflammatory diseases

Obesity is characterized by chronic low-grade inflammation and is strongly associated with multiple immunological diseases, including cancer and inflammatory diseases. Recent animal studies revealed that obesity-induced immunological changes worsen immune-driven diseases and cause resistance to immunotherapy. Here, we discuss the role of obesity in the immunopathology and treatment responses of cancers, respiratory and allergic diseases, and IL-17-mediated inflammatory diseases. We summarize the unique features of the inflammatory state of these diseases, which are orchestrated by obesity. In particular, obesity alters the immune landscape in cancers with a reprogrammed metabolic profile of tumor-infiltrating immune cells. Obesity exacerbates airway inflammation by dysregulating multiple immune-cell subsets. Obesity also dysregulates Th17, IL-17-producing mucosal-associated invariant T (MAIT), and γδ T cells, which contribute to IL-17-mediated inflammatory response in multiple sclerosis, inflammatory bowel disease, psoriasis, atopic dermatitis, and rheumatoid arthritis. By identifying the effects of obesity on immunological diseases, new strategies could be devised to target immune dysregulation caused by obesity.

Targeting dysregulated lipid metabolism in the tumor microenvironment

The reprogramming of lipid metabolism and its association with oncogenic signaling pathways within the tumor microenvironment (TME) have emerged as significant hallmarks of cancer. Lipid metabolism is defined as a complex set of molecular processes including lipid uptake, synthesis, transport, and degradation. The dysregulation of lipid metabolism is affected by enzymes and signaling molecules directly or indirectly involved in the lipid metabolic process. Regulation of lipid metabolizing enzymes has been shown to modulate cancer development and to avoid resistance to anticancer drugs in tumors and the TME. Because of this, understanding the metabolic reprogramming associated with oncogenic progression is important to develop strategies for cancer treatment. Recent advances provide insight into fundamental mechanisms and the connections between altered lipid metabolism and tumorigenesis. In this review, we explore alterations to lipid metabolism and the pivotal factors driving lipid metabolic reprogramming, which exacerbate cancer progression. We also shed light on the latest insights and current therapeutic approaches based on small molecular inhibitors and phytochemicals targeting lipid metabolism for cancer treatment. Further investigations are worthwhile to fully understand the underlying mechanisms and the correlation between altered lipid metabolism and carcinogenesis.

Metabolic influences on T cell in psoriasis: a literature review

Psoriasis is a systemic inflammatory disease that frequently coexists with various other conditions, such as essential hypertension, diabetes, metabolic syndrome, and inflammatory bowel disease. The association between these diseases may be attributed to shared inflammatory pathways and abnormal immunomodulatory mechanisms. Furthermore, metabolites also play a regulatory role in the function of different immune cells involved in psoriasis pathogenesis, particularly T lymphocytes. In this review, we have summarized the current research progress on T cell metabolism in psoriasis, encompassing the regulation of metabolites in glucose metabolism, lipid metabolism, amino acid metabolism, and other pathways within T cells affected by psoriasis. We will also explore the interaction and mechanism between psoriatic metabolites and immune cells. Moreover, we further discussed the research progress of metabolomics in psoriasis to gain a deeper understanding of its pathogenesis and identify potential new therapeutic targets through identification of metabolic biomarkers associated with this condition.

Dysfunctional T Follicular Helper Cells Cause Intestinal and Hepatic Inflammation in NASH

Nonalcoholic steatohepatitis (NASH), characterized by hepatic inflammation and cellular damage, is the most severe form of nonalcoholic fatty liver disease and the fastest-growing indication for a liver transplant. The intestinal immune system is a central modulator of local and systemic inflammation. In particular, Peyer's patches (PPs) contain T follicular helper (Tfh) cells that support germinal center (GC) responses required for the generation of high-affinity intestinal IgA and the maintenance of intestinal homeostasis. However, our understanding of the mechanisms regulating mucosal immunity during the pathogenesis of NASH is incomplete. Here, using a preclinical mouse model that resembles the key features of human disease, we discovered an essential role for Tfh cells in the pathogenesis of NASH. We have found that mice fed a high-fat high-carbohydrate (HFHC) diet have an inflamed intestinal microenvironment, characterized by enlarged PPs with an expansion of Tfh cells. Surprisingly, the Tfh cells in the PPs of NASH mice showed evidence of dysfunction, along with defective GC responses and reduced IgA+ B cells. Tfh-deficient mice fed the HFHC diet showed compromised intestinal permeability, increased hepatic inflammation, and aggravated NASH, suggesting a fundamental role for Tfh cells in maintaining gut-liver homeostasis. Mechanistically, HFHC diet feeding leads to an aberrant increase in the expression of the transcription factor KLF2 in Tfh cells which inhibits its function. Thus, transgenic mice with reduced KLF2 expression in CD4 T cells displayed improved Tfh cell function and ameliorated NASH, including hepatic steatosis, inflammation, and fibrosis after HFHC feeding. Overall, these findings highlight Tfh cells as key intestinal immune cells involved in the regulation of inflammation in the gut-liver axis during NASH.

Obesity is associated with poor outcomes of corticosteroid treatment in patients with primary immune thrombocytopenia

Emerging evidence has demonstrated that obesity impacts multiple immune-related diseases. It remains unclear whether and how obesity alters treatment outcomes in patients with primary immune thrombocytopenia (ITP). Thus, we retrospectively investigated 214 treatment-naïve patients who received standard high-dose dexamethasone therapy in Qilu Hospital. Patients with obesity showed significantly lower overall initial response (underweight vs. normal vs. overweight vs. obese: 85.7% vs. 85.2% vs. 72.0% vs. 52.3%, p = 0.001) and initial complete response ([CR], 71.4% vs. 70.4% vs. 53.3% vs. 27.3%, p < 0.001) rates. The same trend was observed in the 6-month sustained response (63.6% vs. 52.3% vs. 35.6% vs. 22.7%, p = 0.03) and sustained CR (36.4% vs. 44.6% vs. 24.4% vs. 9.1%, p = 0.01). The Kaplan-Meier analysis revealed a shortened duration of remission in the obese group (median duration of remission, not reached vs. 16 months vs. 2 months vs. 1 month, p = 0.002). In multivariate regression analysis, obesity was independently associated with poor initial and sustained responses, and an increased risk for relapse. In conclusion, obesity is a negative predictor for outcomes of corticosteroid treatment. A stratified strategy according to body mass index status may facilitate the precision management of ITP.

Targeting ACC1 in T cells ameliorates psoriatic skin inflammation

Psoriasis is a chronic inflammatory skin disease driven by the IL-23/IL-17 axis. It results from excessive activation of effector T cells, including T helper (Th) and cytotoxic T (Tc) cells, and is associated with dysfunctional regulatory T cells (Tregs). Acetyl-CoA carboxylase 1 (ACC1), a rate-limiting enzyme of fatty acid synthesis (FAS), directs cell fate decisions between Th17 and Tregs and thus could be a promising therapeutic target for psoriasis treatment. Here, we demonstrate that targeting ACC1 in T cells by genetic ablation ameliorates skin inflammation in an experimental model of psoriasis by limiting Th17, Tc17, Th1, and Tc1 cells in skin lesions and increasing the frequency of effector Tregs in skin-draining lymph nodes (LNs). KEY MESSAGES : ACC1 deficiency in T cells ameliorates psoriatic skin inflammation in mice. ACC1 deficiency in T cells reduces IL-17A-producing Th17/Tc17/dysfunctional Treg populations in psoriatic lesions. ACC1 deficiency in T cells restrains IFN-γ-producing Th1/Tc1 populations in psoriatic skin lesions and skin-draining LNs. ACC1 deficiency promotes activated CD44+CD25+ Tregs and effector CD62L-CD44+ Tregs under homeostasis and psoriatic conditions.

Weight loss improves inflammation by T helper 17 cells in an obese patient with psoriasis at high risk for cardiovascular events

Psoriasis is a chronic inflammatory skin disease that is associated with obesity and myocardial infarction. Obesity-induced changes in lipid metabolism promote T helper 17 (Th17) cell differentiation, which in turn promotes chronic inflammation. Th17 cells have central roles in many inflammatory diseases, including psoriasis and atherosclerosis; however, whether treatment of obesity attenuates Th17 cells and chronic inflammatory diseases has been unknown. In this study, we found an increase in Th17 cells in a patient with obesity, type 2 diabetes and psoriasis. Furthermore, weight loss with diet and exercise resulted in a decrease in Th17 cells and improvement of psoriasis. This case supports the hypothesis that obesity leads to an increase in Th17 cells and chronic inflammation of the skin and blood vessel walls, thereby promoting psoriasis and atherosclerosis.

1-Oleoyl-lysophosphatidylethanolamine stimulates RORγt activity in TH17 cells

Metabolic fluxes involving fatty acid biosynthesis play essential roles in controlling the differentiation of T helper 17 (TH17) cells. However, the exact enzymes and lipid metabolites involved, as well as their link to promoting the core gene transcriptional signature required for the differentiation of TH17 cells, remain largely unknown. From a pooled CRISPR-based screen and unbiased lipidomics analyses, we identified that 1-oleoyl-lysophosphatidylethanolamine could act as a lipid modulator of retinoid-related orphan receptor gamma t (RORγt) activity in TH17 cells. In addition, we specified five enzymes, including Gpam, Gpat3, Lplat1, Pla2g12a, and Scd2, suggestive of the requirement of glycerophospholipids with monounsaturated fatty acids being required for the transcription of Il17a. 1-Oleoyl-lysophosphatidylethanolamine was reduced in Pla2g12a-deficient TH17 cells, leading to the abolition of interleukin-17 (IL-17) production and disruption to the core transcriptional program required for the differentiation of TH17 cells. Furthermore, mice with T cell-specific deficiency of Pla2g12a failed to develop disease in an experimental autoimmune encephalomyelitis model of multiple sclerosis. Thus, our data indicate that 1-oleoyl-lysophosphatidylethanolamine is a lipid metabolite that promotes RORγt-induced TH17 cell differentiation and the pathogenicity of TH17 cells.

Morin, the PPARγ agonist, inhibits Th17 differentiation by limiting fatty acid synthesis in collagen-induced arthritis

T helper (Th) 17 cells highly contribute to the immunopathology of rheumatoid arthritis. Morin, a natural flavonoid, owns well anti-arthritic action but unclear effect on Th17 differentiation. This study tried to solve this issue and explore the mechanisms in view of cellular metabolism. Naïve CD4+ T cells were treated with anti-CD3/CD28 along with Th17-inducing cytokines. Morin was shown to block Th17 differentiation without affecting cell viability even when Foxp3 was dampened. The mechanisms were ascribed to the limited fatty acid synthesis by restricting FASN transcription, as indicated by metabolomics analysis, nile red staining, detection of triglycerides, FASN overexpression, and addition of palmitic acid. Moreover, morin had slight effect on cell apoptosis and protein palmitoylation during Th17 differentiation, but blocked the binding of RORγt to promoter and CNS2 region of Il17a gene. Oleic acid rescued the inhibition of morin on RORγt function, and Th17-inducing cytokines could not induce RORγt function in SCD1-defficient cells, suggesting that oleic acid but not palmitic acid was the direct effector in the action of morin. Then, PPARγ was identified as the target of morin, and GW9662 or PPARγ CRISPR/Cas9 KO plasmid weakened its above-mentioned effects. The transrepression of FASN by morin was owing to physical interaction between PPARγ and Sp1, and the importance of Sp1 in Th17 differentiation was confirmed by siSp1. Finally, the effects and mechanisms for morin-dampened Th17 responses were confirmed in collagen-induced arthritis (CIA) mice. Collectively, morin inhibited Th17 differentiation and alleviated CIA by limiting fatty acid synthesis subsequent to PPARγ activation.

Modulation of immunity by the secreted phospholipase A2 family

Among the phospholipase A2 (PLA2 ) superfamily, which typically catalyzes the sn-2 hydrolysis of phospholipids to yield fatty acids and lysophospholipids, the secreted PLA2 (sPLA2 ) family contains 11 isoforms in mammals. Individual sPLA2 s have unique enzymatic specificity toward fatty acids and polar heads of phospholipid substrates and display distinct tissue/cellular distributions, suggesting their distinct physiological functions. Recent studies using knockout and/or transgenic mice for a full set of sPLA2 s have revealed their roles in modulation of immunity and related disorders. Application of mass spectrometric lipidomics to these mice has enabled to identify target substrates and products of individual sPLA2 s in given tissue microenvironments. sPLA2 s hydrolyze not only phospholipids in the plasma membrane of activated, damaged or dying mammalian cells, but also extracellular phospholipids such as those in extracellular vesicles, microbe membranes, lipoproteins, surfactants, and dietary phospholipids, thereby exacerbating or ameliorating various diseases. The actions of sPLA2 s are dependent on, or independent of, the generation of fatty acid- or lysophospholipid-derived lipid mediators according to the pathophysiological contexts. In this review, we make an overview of our current understanding of the roles of individual sPLA2 s in various immune responses and associated diseases.

Exploring the roles of prostanoids, leukotriens, and dietary fatty acids in cutaneous inflammatory diseases: Insights from pharmacological and genetic approaches

Prostanoids and leukotrienes (LTs) are representative of ω6 fatty acid-derived metabolites that exert their actions through specific receptors on the cell surface. These lipid mediators, being unstable in vivo, act locally at their production sites; thus, their physiological functions remain unclear. However, recent pharmacological and genetic approaches using experimental murine models have provided significant insights into the roles of these lipid mediators in various pathophysiological conditions, including cutaneous inflammatory diseases. These lipid mediators act not only through signaling by themselves but also by potentiating the signaling of other chemical mediators, such as cytokines and chemokines. For instance, prostaglandin E2 -EP4 and LTB4 -BLT1 signaling on cutaneous dendritic cells substantially facilitate their chemokine-induced migration ability into the skin and play critical roles in the priming and/or activation of antigen-specific effector T cells in the skin. In addition to these ω6 fatty acid-derived metabolites, various ω3 fatty acid-derived metabolites regulate skin immune cell functions, and some exert potent anti-inflammatory functions. Lipid mediators act as modulators of cutaneous immune responses, and manipulating the signaling from lipid mediators has the potential as a novel therapeutic approach for human skin diseases.

Differential impact of environmental factors on systemic and localized autoimmunity

The influence of environmental factors on the development of autoimmune disease is being broadly investigated to better understand the multifactorial nature of autoimmune pathogenesis and to identify potential areas of intervention. Areas of particular interest include the influence of lifestyle, nutrition, and vitamin deficiencies on autoimmunity and chronic inflammation. In this review, we discuss how particular lifestyles and dietary patterns may contribute to or modulate autoimmunity. We explored this concept through a spectrum of several autoimmune diseases including Multiple Sclerosis (MS), Systemic Lupus Erythematosus (SLE) and Alopecia Areata (AA) affecting the central nervous system, whole body, and the hair follicles, respectively. A clear commonality between the autoimmune conditions of interest here is low Vitamin D, a well-researched hormone in the context of autoimmunity with pleiotropic immunomodulatory and anti-inflammatory effects. While low levels are often correlated with disease activity and progression in MS and AA, the relationship is less clear in SLE. Despite strong associations with autoimmunity, we lack conclusive evidence which elucidates its role in contributing to pathogenesis or simply as a result of chronic inflammation. In a similar vein, other vitamins impacting the development and course of these diseases are explored in this review, and overall diet and lifestyle. Recent work exploring the effects of dietary interventions on MS showed that a balanced diet was linked to improvement in clinical parameters, comorbid conditions, and overall quality of life for patients. In patients with MS, SLE and AA, certain diets and supplements are linked to lower incidence and improved symptoms. Conversely, obesity during adolescence was linked with higher incidence of MS while in SLE it was associated with organ damage. Autoimmunity is thought to emerge from the complex interplay between environmental factors and genetic background. Although the scope of this review focuses on environmental factors, it is imperative to elaborate the interaction between genetic susceptibility and environment due to the multifactorial origin of these disease. Here, we offer a comprehensive review about the influence of recent environmental and lifestyle factors on these autoimmune diseases and potential translation into therapeutic interventions.

Role of T cells in the pathogenesis of systemic lupus erythematous: Focus on immunometabolism dysfunctions

Evidence demonstrates that T cells are implicated in developing SLE, and each of them dominantly uses distinct metabolic pathways. Indeed, intracellular enzymes and availability of specific nutrients orchestrate fate of T cells and lead to differentiation of regulatory T cells (Treg), memory T cells, helper T cells, and effector T cells. The function of T cells in inflammatory and autoimmune responses is determined by metabolic processes and activity of their enzymes. Several studies were conducted to determine metabolic abnormalities in SLE patients and clarify how these modifications could control the functions of the involved T cells. Metabolic pathways such as glycolysis, mitochondrial pathways, oxidative stress, mTOR pathway, fatty acid and amino acid metabolisms are dysregulated in SLE T cells. Moreover, immunosuppressive drugs used in treating autoimmune diseases, including SLE, could affect immunometabolism. Developing drugs to regulate autoreactive T cell metabolism could be a promising therapeutic approach for SLE treatment. Accordingly, increased knowledge about metabolic processes paves the way to understanding SLE pathogenesis better and introduces novel therapeutic options for SLE treatment. Although monotherapy with metabolic pathways modulators might not be sufficient to prevent autoimmune disease, they may be an ideal adjuvant to reduce administration doses of immunosuppressive drugs, thus reducing drug-associated adverse effects. This review summarized emerging data about T cells that are involved in SLE pathogenesis, focusing on immunometabolism dysregulation and how these modifications could affect the disease development.

Fatty acid desaturation by stearoyl-CoA desaturase-1 controls regulatory T cell differentiation and autoimmunity

The imbalance between pathogenic and protective T cell subsets is a cardinal feature of autoimmune disorders such as multiple sclerosis (MS). Emerging evidence indicates that endogenous and dietary-induced changes in fatty acid metabolism have a major impact on both T cell fate and autoimmunity. To date, however, the molecular mechanisms that underlie the impact of fatty acid metabolism on T cell physiology and autoimmunity remain poorly understood. Here, we report that stearoyl-CoA desaturase-1 (SCD1), an enzyme essential for the desaturation of fatty acids and highly regulated by dietary factors, acts as an endogenous brake on regulatory T-cell (Treg) differentiation and augments autoimmunity in an animal model of MS in a T cell-dependent manner. Guided by RNA sequencing and lipidomics analysis, we found that the absence of Scd1 in T cells promotes the hydrolysis of triglycerides and phosphatidylcholine through adipose triglyceride lipase (ATGL). ATGL-dependent release of docosahexaenoic acid enhanced Treg differentiation by activating the nuclear receptor peroxisome proliferator-activated receptor gamma. Our findings identify fatty acid desaturation by SCD1 as an essential determinant of Treg differentiation and autoimmunity, with potentially broad implications for the development of novel therapeutic strategies and dietary interventions for autoimmune disorders such as MS.

Lipid metabolism in Th17 cell function

Among the subset of T helper cells, Th17 cells are known to play a crucial role in the pathogenesis of various autoimmune disorders, such as psoriasis, rheumatoid arthritis, inflammatory bowel disease, steroid-resistant asthma, and multiple sclerosis. The master transcription factor retinoid-related orphan receptor gamma t (RORγt), a nuclear hormone receptor, plays a vital role in inducing Th17-cell differentiation. Recent findings suggest that metabolic control is critical for Th17-cell differentiation, particularly through the engagement of de novo lipid biosynthesis. Inhibition of lipid biosynthesis, either through the use of pharmacological inhibitors or by the deficiency of related enzymes in CD4⁺ T cells, results in significant suppression of Th17-cell differentiation. Mechanistic studies indicate that metabolic fluxes through both the fatty acid and cholesterol biosynthetic pathways are essential for controlling RORγt activity through the generation of a lipid ligand of RORγt. This review highlights recent findings that underscore the significant role of lipid metabolism in the differentiation and function of Th17 cells, as well as elucidating the distinctive molecular pathways that drive the activation of RORγt by cellular lipid metabolism. We further elaborate on a pioneering therapeutic approach for ameliorating autoimmune disorders via the inhibition of RORγt.

Goliath induces inflammation in obese mice by linking fatty acid β-oxidation to glycolysis

Obesity is associated with metabolic disorders and chronic inflammation. However, the obesity-associated metabolic contribution to inflammatory induction remains elusive. Here, we show that, compared with lean mice, CD4+ T cells from obese mice exhibit elevated basal levels of fatty acid β-oxidation (FAO), which promote T cell glycolysis and thus hyperactivation, leading to enhanced induction of inflammation. Mechanistically, the FAO rate-limiting enzyme carnitine palmitoyltransferase 1a (Cpt1a) stabilizes the mitochondrial E3 ubiquitin ligase Goliath, which mediates deubiquitination of calcineurin and thus enhances activation of NF-AT signaling, thereby promoting glycolysis and hyperactivation of CD4+ T cells in obesity. We also report the specific GOLIATH inhibitor DC-Gonib32, which blocks this FAO-glycolysis metabolic axis in CD4+ T cells of obese mice and reduces the induction of inflammation. Overall, these findings establish a role of a Goliath-bridged FAO-glycolysis axis in mediating CD4+ T cell hyperactivation and thus inflammation in obese mice.

New insights into the metabolism of Th17 cells

T helper 17 (Th17) cells are IL-17-producing CD4 T cells that play a crucial role in autoimmune diseases. IL-17 is a key cytokine for host protection against mucosal and skin infection but is also one of the major pathogenic cytokines. IL-1 and IL-23 are requisite for stimulating pathogenic Th17 cell differentiation and proliferation. Therapeutics targeting the IL-17/IL-23 pathway are widely used clinically for the treatment of autoimmune diseases. Besides IL-17, pathogenic Th17 cells produce granulocyte-macrophage colony-stimulating factor, tumor necrosis factor α, interferon γ, IL-21 and IL-22. However, Th17-targeted therapy has not yet been established. T cell metabolism orchestrates T cell survival, cell differentiation, epigenetic change and function and each T cell subset favors a particular metabolic pathway. Recent studies have provided novel insights into the role of T cell metabolism in the pathogenesis of autoimmune diseases. The current review focuses on the role of Th17 cell metabolism in autoimmune diseases, particularly glycolysis, amino acid metabolism, lipid metabolism, as well as the regulators of these processes, including mTORC1. Therapeutics targeting T cell metabolism in autoimmune diseases could serve as a possible treatment option for patients who are refractory to or unresponsive to conventional therapy.

Itaconate ameliorates autoimmunity by modulating T cell imbalance via metabolic and epigenetic reprogramming

Dysregulation of Th17 and Treg cells contributes to the pathophysiology of many autoimmune diseases. Herein, we show that itaconate, an immunomodulatory metabolite, inhibits Th17 cell differentiation and promotes Treg cell differentiation by orchestrating metabolic and epigenetic reprogramming. Mechanistically, itaconate suppresses glycolysis and oxidative phosphorylation in Th17- and Treg-polarizing T cells. Following treatment with itaconate, the S-adenosyl-L-methionine/S-adenosylhomocysteine ratio and 2-hydroxyglutarate levels are decreased by inhibiting the synthetic enzyme activities in Th17 and Treg cells, respectively. Consequently, these metabolic changes are associated with altered chromatin accessibility of essential transcription factors and key gene expression in Th17 and Treg cell differentiation, including decreased RORγt binding at the Il17a promoter. The adoptive transfer of itaconate-treated Th17-polarizing T cells ameliorates experimental autoimmune encephalomyelitis. These results indicate that itaconate is a crucial metabolic regulator for Th17/Treg cell balance and could be a potential therapeutic agent for autoimmune diseases.

Role of FABP5 in T Cell Lipid Metabolism and Function in the Tumor Microenvironment

To evade immune surveillance, tumors develop a hostile microenvironment that inhibits anti-tumor immunity. Recent immunotherapy breakthroughs that target the reinvigoration of tumor-infiltrating T lymphocytes (TIL) have led to unprecedented success in treating some cancers that are resistant to conventional therapy, suggesting that T cells play a pivotal role in anti-tumor immunity. In the hostile tumor microenvironment (TME), activated T cells are known to mainly rely on aerobic glycolysis to facilitate their proliferation and anti-tumor function. However, TILs usually exhibit an exhausted phenotype and impaired anti-tumor activity due to the limited availability of key nutrients (e.g., glucose) in the TME. Given that different T cell subsets have unique metabolic pathways which determine their effector function, this review introduces our current understanding of T cell development, activation signals and metabolic pathways. Moreover, emerging evidence suggests that fatty acid binding protein 5 (FABP5) expression in T cells regulates T cell lipid metabolism and function. We highlight how FABP5 regulates fatty acid uptake and oxidation, thus shaping the survival and function of different T cell subsets in the TME.

Asthma, obesity, and microbiota: A complex immunological interaction

Obesity and allergic asthma are inflammatory chronic diseases mediated by distinct immunological features, obesity presents a Th1/Th17 profile, asthma is commonly associated with Th2 response. However, when combined, they result in more severe asthma symptoms, greater frequency of exacerbation episodes, and lower therapy responsiveness. These features lead to decreased life quality, associated with higher morbidity/mortality rates.  In addition, obesity prompts specific asthma phenotypes, which can be dependent on atopic status, age, and gender. In adults, obesity is associated with neutrophilic/Th17 profile, while in children, the outcome is diverse, in some cases children with obesity present aggravation of atopy, and Th2 inflammation, and in others an association with a Th1 profile, with reduced IgE levels and eosinophilia. These alterations occur due to a complex group of factors among which the microbiome has been recently explored. Particularly, evidence shows its important role in susceptibility or resistance to asthma development, via gut-lung-axis, and demonstrates its relevance to the immune pathogenesis of the syndrome. Few studies address the relevance of the lung microbiome in shaping the immune response, locally. However, specific bacteria, like Moraxella catarrhalis, Haemophilus influenza, and Streptococcus pneumoniae, correlate with important features of the obese-asthmatic phenotype. Although maternal obesity is known to increase asthma risk in offspring, the impact on lung colonization is unknown. This review details the main key immune mechanisms involved in obesity-aggravated asthma, featuring the effect of maternal obesity in the establishment of gut and lung microbiota of the offspring, acting as potential childhood asthma inducer.

The Increased Risk of Hypertension Caused by Irrational Dietary Pattern May Be Associated with Th17 Cell in the Middle-Aged and Elderly Rural Residents of Beijing City, Northern China: A 1:1 Matched Case-Control Study

An irrational diet has been widely considered as one of the vital risk factors of hypertension. Previous studies have indicated that immune dysfunction may be involved in the pathogenic process of hypertension, while fewer studies have mentioned whether CD4+ T cells are involved in the association between dietary pattern and hypertension. This present 1:1 matched case-control study was conducted to analyze the association among dietary pattern, CD4+ T cells and hypertension. A total of 56 patients with diagnosed hypertension and 56 subjects without diagnosed hypertension in the rural area of Beijing City, northern China, were matched by age and gender, and then classified into a case group and a control group, respectively. Compared with the control group, higher frequencies of pro-inflammatory CD4+ T cells, such as Th1, Th1(IFN-γ), Th17(IL-17A), and Th1/17 (IFN-γ/IL-17A), were found in the case group (p < 0.05). A significantly higher level of circulating IL-17A was also found in the case group (7.4 pg/mL vs. 8.2 pg/mL, p < 0.05). Five dietary patterns were identified using exploratory factor analysis. An irrational dietary pattern, characterized by high-factor loadings of refined wheat (0.65), meat (0.78), poultry (0.76), and alcoholic beverage (0.73), was positively associated with SBP (β = 5.38, 95%CI = 0.73~10.03, p < 0.05) in the multiple linear regression model with the adjustment of potential covariates. The other dietary patterns showed no significant association with blood pressure. Furthermore, meat, processed meat, and animal viscera were positively correlated with the peripheral Th17 or Th1/17. In conclusion, the irrational dietary pattern characterized by refined wheat, meat, poultry, and alcoholic beverage, was positively correlated with blood pressure, and may increase the risk of hypertension in the rural area of Beijing, northern China. Th17, a subset of the CD4+ T helper cells, may be involved in the association between irrational dietary pattern and hypertension.

The Value of Interleukin-17A as a Prognostic Indicator in COVID-19 Patients

Background: SARS-CoV-2 infections (COVID-19) first occurred in Wuhan, China, in December 2019 and spread worldwide, causing significant mortality and morbidity. IL-17A may mediate numerous immunopathological effects secondary to cytokine release syndrome during SARS-CoV-2 infection. However, there has not been enough research on its effect on prognosis. Objectives: This study evaluated the predictive power of serum interleukin (IL)-17A level as a prognostic marker in COVID-19. Methods: The study included 152 patients diagnosed with COVID-19 by real-time polymerase chain reaction analysis of nasopharyngeal swab samples in the infectious diseases department and intensive care unit of our hospital between October 1 and December 31, 2020. The control group consisted of 40 asymptomatic healthcare workers who had negative RT-PCR results during routine COVID-19 screening in our hospital. Samples were collected in anticoagulant-free tubes and left at room temperature for 30 minutes. Afterward, it was centrifuged at 1000 × g for 15 minutes at 4°C per the instructions provided with the enzyme-linked immunoassay (ELISA) kit. Serum IL-17A levels were measured using the Human Interleukin 17A ELISA Kit. Results: Serum IL-17A levels were significantly higher in COVID-19 patients than in controls (P < 0.001). IL-17A levels increased significantly in association with disease severity in patients with the moderate, severe, and critical disease, with a less pronounced difference between severe and critical patients (moderate vs. severe, P < 0.001; severe vs. critical, P = 0.048). IL-17A levels at hospital admission and day 7 were significantly higher in non-surviving patients (P < 0.001). At a cut-off value of 210.25 ng/L, IL-17A at admission had a predictive power of 0.792 (P < 0.001). Compared to baseline, IL-17A values on day seven were significantly increased in non-survivors (P = 0.004) and decreased in survivors (P = 0.014). An increase of 26.17 ng/L or more on day 7 had a predictive mortality power of 0.634 (P = 0.005). Conclusions: The results of this study suggest that IL-17A, an important part of the immune system previously shown to be useful in the treatment and follow-up of COVID-19, may also help predict mortality in COVID-19 patients.

Comprehensive analysis of the prognosis, tumor microenvironment, and immunotherapy response of SDHs in colon adenocarcinoma

Background

Succinate dehydrogenase (SDH), one of the key enzymes in the tricarboxylic acid cycle, is mainly found in the mitochondria. SDH consists of four subunits encoding SDHA, SDHB, SDHC, and SDHD. The biological function of SDH is significantly related to cancer progression. Colorectal cancer (CRC) is one of the most common malignant tumors globally, whose most common histological subtype is colon adenocarcinoma (COAD). However, the correlation between SDH factors and COAD remains unclear.

Methods

The data on pan-cancer was obtained from The Cancer Genome Atlas (TCGA) database. Kaplan-Meier survival analysis showed the prognostic ability of SDHs. The cBioPortal database reflected genetic variations of SDHs. The correlation analysis was conducted between SDHs and mitochondrial energy metabolism genes (MMGs) and the protein-protein interaction (PPI) network was built. Consequently, Univariate and Multivariate Cox Regression Analysis on SDHs and other clinical characteristics were conducted. A nomogram was established. The ssGSEA analysis visualized the association between SDHs and immune infiltration. Immunophenoscore (IPS) explored the correlation between SDHs and immunotherapy, and the correlation between SDHs and targeted therapy was investigated through Genomics of Drug Sensitivity in Cancer. Finally, qPCR and immunohistochemistry detected SDHs' expression.

Results

After assessing SDHs differential expression in pan-cancer, we found that SDHB, SDHC, and SDHD benefit COAD patients. The cBioPortal database demonstrated that SDHA was the top gene in mutation frequency rank. Correlation analysis mirrored a strong link between SDHs and MMGs. We formulated a nomogram and found that SDHB, SDHC, SDHD, and clinical characteristics correlated with COAD patients' survival. For T helper cells, Th2 cells, and Tem, SDHA, SDHB, SDHC, and SDHD were significantly enriched in the high expression group. Moreover, COAD patients with high SDHA expression were more suitable for immunotherapy. And COAD patients with different SDHs' expression have different sensitivity to targeted drugs. Further verifying the gene and protein expression levels of SDHs, we found that the tissues were consistent with the bioinformatics analysis.

Conclusions

Our study analyzed the expression and prognostic value of SDHs in COAD, explored the pathway mechanisms involved, and the immune cell correlations, indicating that SDHs might be biomarkers for COAD patients.

Characterization of proteogenomic signatures of differentiation of CD4+ T cell subsets

Functionally distinct CD4+ helper T (Th) cell subsets, including Th1, Th2, Th17, and regulatory T cells (Treg), play a pivotal role in the regulation of acquired immunity. Although the key proteins involved in the regulation of Th cell differentiation have already been identified how the proteogenomic landscape changes during the Th cell activation remains unclear. To address this issue, we characterized proteogenomic signatures of differentiation to each Th cell subsets by RNA sequencing and liquid chromatography-assisted mass spectrometry, which enabled us to simultaneously quantify more than 10,000 protein-coding transcripts and 8,000 proteins in a single-shot. The results indicated that T cell receptor activation affected almost half of the transcript and protein levels in a low correlative and gene-specific manner, and specific cytokine treatments modified the transcript and protein profiles in a manner specific to each Th cell subsets: Th17 and Tregs particularly exhibited unique proteogenomic signatures compared to other Th cell subsets. Interestingly, the in-depth proteome data revealed that mRNA profiles alone were not enough to delineate functional changes during Th cell activation, suggesting that the proteogenomic dataset obtained in this study serves as a unique and indispensable data resource for understanding the comprehensive molecular mechanisms underlying effector Th cell differentiation.

Vitamin B5 rewires Th17 cell metabolism via impeding PKM2 nuclear translocation

Metabolic rewiring is essential for Th17 cells' functional identity to sense and interpret environmental cues. However, the environmental metabolic checkpoints with specific regulation of Th17 cells, manifesting potential therapeutic opportunities to autoimmune diseases, remain largely unknown. Here, by screening more than one hundred compounds derived from intestinal microbes or diet, we found that vitamin B5 (VB5) restrains Th17 cell differentiation as well as related autoimmune diseases such as experimental autoimmune encephalomyelitis and colitis. Mechanistically, VB5 is catabolized into coenzyme A (CoA) in a pantothenate kinase (PANK)-dependent manner, and in turn, CoA binds to pyruvate kinase isoform 2 (PKM2) to impede its phosphorylation and nuclear translocation, thus inhibiting glycolysis and STAT3 phosphorylation. In humans, reduced serum VB5 levels are found in both IBD and MS patients. Collectively, our study demonstrates a role of VB5 in Th17 cell metabolic reprograming, thus providing a potential therapeutic intervention for Th17 cell-associated autoimmune diseases.

Regulation of Progression and Resolution of Liver Fibrosis by Immune Cells

The excessive accumulation of extracellular matrix proteins results in fibrosis-a condition implicated in several diseased conditions, such as nonalcoholic steatohepatitis, viral hepatitis, and autoimmune hepatitis. Despite its prevalence, direct and effective treatments for fibrosis are lacking, warranting the development of better therapeutic strategies. Accumulating evidence has shown that liver fibrosis-a condition previously considered irreversible-is reversible in specific conditions. Immune cells residing in or infiltrating the liver (e.g., macrophages) are crucial in the pathogenesis of fibrosis. Given this background, the roles and action mechanisms of various immune cells and their subsets in the progression and recovery of liver fibrosis, particularly concerning nonalcoholic steatohepatitis, are discussed in this review. Furthermore, the development of better therapeutic strategies based on stage-specific properties and using advanced techniques as well as the mechanisms underlying recovery are elaborated. In conclusion, we consider the review comprehensively provides the present achievements and future possibilities revolving around fibrosis treatment.

Do Sleep Disorders and Western Diet Influence Psoriasis? A Scoping Review

Western diet may trigger sleep disorders and vice versa, but their single and mutual effects on systemic inflammatory diseases (i.e., psoriasis) are far from being fully elucidated. At the same time, psoriatic patients display a great burden of sleep disorders and dysmetabolisms related to an unhealthy lifestyle (i.e., diet). These patients are also affected by a chronic disorder deeply modulated by environmental factors (i.e., sleep and diet) capable to influence drug-response and disease progression. Thus, we aimed to summarize the evidence in the literature that may highlight a potential link among psoriasis–diet–sleep in order to further promote a multidisciplinary approach to psoriatic patients in the scientific community.

Fatty acid metabolism in T-cell function and differentiation

Immunometabolism has recently emerged as a field of study examining the intersection between immunology and metabolism. Studies in this area have yielded new findings on the roles of a diverse range of metabolic pathways and metabolites, which have been found to control many aspects of T-cell biology, including cell differentiation, function and fate. A particularly important finding has been the discovery that to meet the energy requirements associated with their proliferation, activation and specific functions, T cells switch their metabolic signatures during differentiation. For example, whereas the induction of de novo fatty acid biosynthesis and fatty acid uptake programs are required for antigen-stimulation-induced proliferation and differentiation of effector T cells, fatty acid catabolism via β-oxidation is essential for the generation of memory T cells and the differentiation of regulatory T cells. In this review, we discuss recent advances in our understanding of the metabolism in different stages of T cells and how fatty acid metabolism in these cells controls their specific functions.

T-cell Metabolism as Interpreted in Obesity-associated Inflammation

The appreciation of metabolic regulation of T-cell function has exploded over the past decade, as has our understanding of how inflammation fuels comorbidities of obesity, including type 2 diabetes. The likelihood that obesity fundamentally alters T-cell metabolism and thus chronic obesity-associated inflammation is high, but studies testing causal relationships remain underrepresented. We searched PubMed for key words including mitochondria, obesity, T cell, type 2 diabetes, cristae, fission, fusion, redox, and reactive oxygen species to identify foundational and more recent studies that address these topics or cite foundational work. We investigated primary papers cited by reviews found in these searches and highlighted recent work with >100 citations to illustrate the state of the art in understanding mechanisms that control metabolism and thus function of various T-cell subsets in obesity. However, "popularity" of a paper over the first 5 years after publication cannot assess long-term impact; thus, some likely important work with fewer citations is also highlighted. We feature studies of human cells, supplementing with studies from animal models that suggest future directions for human cell research. This approach identified gaps in the literature that will need to be filled before we can estimate efficacy of mitochondria-targeted drugs in clinical trials to alleviate pathogenesis of obesity-associated inflammation.

Recent Advances Regarding the Molecular Mechanisms of Triterpenic Acids: A Review (Part II)

Triterpenic acids are a widespread class of phytocompounds which have been found to possess valuable therapeutic properties such as anticancer, anti-inflammatory, hepatoprotective, cardioprotective, antidiabetic, neuroprotective, lipolytic, antiviral, and antiparasitic effects. They are a subclass of triterpenes bearing a characteristic lipophilic structure that imprints unfavorable in vivo properties which subsequently limit their applications. The early investigation of the mechanism of action (MOA) of a drug candidate can provide valuable information regarding the possible side effects and drug interactions that may occur after administration. The current paper aimed to summarize the most recent (last 5 years) studies regarding the MOA of betulinic acid, boswellic acid, glycyrrhetinic acid, madecassic acid, moronic acid, and pomolic acid in order to provide scientists with updated and accessible material on the topic that could contribute to the development of future studies; the paper stands as the sequel of our previously published paper regarding the MOA of triterpenic acids with therapeutic value. The recent literature published on the topic has highlighted the role of triterpenic acids in several signaling pathways including PI3/AKT/mTOR, TNF-alpha/NF-kappa B, JNK-p38, HIF-α/AMPK, and Grb2/Sos/Ras/MAPK, which trigger their various biological activities.

Obesity, Inflammation, and Immune System in Osteoarthritis

Obesity remains the most important risk factor for the incidence and progression of osteoarthritis (OA). The leading cause of OA was believed to be overloading the joints due to excess weight which in turn leads to the destruction of articular cartilage. However, recent studies have proved otherwise, various other factors like adipose deposition, insulin resistance, and especially the improper coordination of innate and adaptive immune responses may lead to the initiation and progression of obesity-associated OA. It is becoming increasingly evident that multiple inflammatory cells are recruited into the synovial joint that serves an important role in pathological changes in the synovial joint. Polarization of macrophages and macrophage-produced mediators are extensively studied and linked to the inflammatory and destructive responses in the OA synovium and cartilage. However, the role of other major innate immune cells such as neutrophils, eosinophils, and dendritic cells in the pathogenesis of OA has not been fully evaluated. Although cells of the adaptive immune system contribute to the pathogenesis of obesity-induced OA is still under exploration, a quantity of literature indicates OA synovium has an enriched population of T cells and B cells compared with healthy control. The interplay between a variety of immune cells and other cells that reside in the articular joints may constitute a vicious cycle, leading to pathological changes of the articular joint in obese individuals. This review addresses obesity and the role of all the immune cells that are involved in OA and summarised animal studies and human trials and knowledge gaps between the studies have been highlighted. The review also touches base on the interventions currently in clinical trials, different stages of the testing, and their shortcomings are also discussed to understand the future direction which could help in understanding the multifactorial aspects of OA where inflammation has a significant function.

Intracellular Ca2+ Signaling and Calcium Release-Activated Calcium Modulator ORAI1 Are Associated With CD4+ T Lymphocytes in Dairy Cows

The nutritional status of dairy cows and the metabolism of specific nutrients are critical regulators of immune cell function. Around the time of parturition, mobilization of body lipid and muscle helps compensate for the decrease in nutrient intake and the increased requirements of the mammary gland for lactation. An end-result of these processes is the marked increase in circulating concentrations of fatty acids (FA), which are a major risk factor for immune dysfunction. In food animal species such as dairy cows, any disturbance in nutritional or immunological homeostasis leads to deleterious feedback loops that can further risk health, efficiency of nutrient use, and compromise availability of safe and nutritious dairy foods for humans. Despite substantial progress with respect to regulation of innate immunity, such knowledge for adaptive immunity is scarce. To help bridge this gap in knowledge, we sought to study the role of calcium release-activated calcium modulator ORAI1 activation in T cells systemic immune function in vivo. CD4⁺ T cells were isolated from peripheral blood of dairy cows diagnosed as healthy or with ketosis, a common metabolic disorder of FA metabolism. Results revealed that levels of intracellular Ca²⁺ and reactive oxygen species (ROS) along with the abundance of store-operated Ca²⁺ entry (SOCE) moiety increased during ketosis. Further, plasma concentrations of inflammatory cytokines were elevated, the balance of Th17/Treg cells was disrupted, mitochondrial function impaired, and the abundance of mitophagy-related proteins in CD4⁺ T cells altered during ketosis. Molecular characterization of the direct effects of FA was evaluated in CD4⁺ T cells isolated from the spleen of 1-day-old calves. Enhanced supply of FA increased intracellular Ca²⁺ and ROS concentrations, upregulated the abundance of proteins associated with mitochondrial dynamics and ORAI1. Intermediates of mitophagy accumulated and the balance of Th17/Treg cells also was affected by the supply of FA. These negative effects were attenuated by silencing or inhibition of ORAI1 in CD4⁺ T cells. Together, data indicated that physiological states that lead to increases in systemic concentrations of FA could impact adaptive immunity negatively through ORAI1 regulated intracellular Ca²⁺, ROS balance, and increased effector functions of Th17 cells.

Maternal body mass index is associated with an altered immunological profile at 28 weeks of gestation

Healthy pregnancy is accompanied by various immunological and metabolic adaptations. Maternal obesity has been implicated in adverse pregnancy outcomes such as miscarriage, preeclampsia, and gestational diabetes mellitus (GDM), while posing a risk to the neonate. There is a lack of knowledge surrounding obesity and the maternal immune system. The objective of this study was to consider if immunological changes in pregnancy are influenced by maternal obesity. Peripheral blood was collected from fasted GDM-negative pregnant women at 26-28 weeks of gestation. Analysis was done using immunoassay, flow cytometry, bioenergetics analysis, and cell culture. The plasma profile was significantly altered with increasing BMI, specifically leptin (r = 0.7635), MCP-1 (r = 0.3024), and IL-6 (r = 0.4985). Circulating leukocyte populations were also affected with changes in the relative abundance of intermediate monocytes (r = -0.2394), CD4:CD8 T-cell ratios (r = 0.2789), and NKT cells (r = -0.2842). Monocytes analysed in more detail revealed elevated CCR2 expression and decreased mitochondrial content with increased BMI. However, LPS-stimulated cytokine production and bioenergetic profile of PBMCs were not affected by maternal BMI. The Th profile skews towards Th17 with increasing BMI; Th2 (r = -0.3202) and Th9 (r = -0.3205) cells were diminished in maternal obesity, and CytoStim™-stimulation exacerbates IL-6 (r = 0.4166), IL-17A (r = 0.2753), IL-17F (r = 0.2973), and IL-22 (r = 0.2257) production with BMI, while decreasing IL-4 (r = -0.2806). Maternal obesity during pregnancy creates an inflammatory microenvironment. Successful pregnancy requires Th2-biased responses yet increasing maternal BMI favours a Th17 response that could be detrimental to pregnancy. Further research should investigate key populations of cells identified here to further understand the immunological challenges that beset pregnant women with obesity.

Fatty Acid Metabolism and T Cells in Multiple Sclerosis

Cellular metabolic remodeling is intrinsically linked to the development, activation, differentiation, function, and survival of T cells. T cells transition from a catabolic, naïve state to an anabolic effector state upon T cell activation. Subsequently, specialization of T cells into T helper (Th) subsets, including regulatory T cells (Treg), requires fine-tuning of metabolic programs that better support and optimize T cell functions for that particular environment. Increasingly, studies have shown that changes in nutrient availability at both the cellular and organismal level during disease states can alter T cell function, highlighting the importance of better characterizing metabolic-immune axes in both physiological and disease settings. In support of these data, a growing body of evidence is emerging that shows specific lipid species are capable of altering the inflammatory functional phenotypes of T cells. In this review we summarize the metabolic programs shown to support naïve and effector T cells, and those driving Th subsets. We then discuss changes to lipid profiles in patients with multiple sclerosis, and focus on how the presence of specific lipid species can alter cellular metabolism and function of T cells.

Lipid metabolism in T cell signaling and function

T cells orchestrate adaptive immunity against pathogens and other immune challenges, but their dysfunction can also mediate the pathogenesis of cancer and autoimmunity. Metabolic adaptation in response to immunological and microenvironmental signals contributes to T cell function and fate decision. Lipid metabolism has emerged as a key regulator of T cell responses, with selective lipid metabolites serving as metabolic rheostats to integrate environmental cues and interplay with intracellular signaling processes. Here, we discuss how extracellular, de novo synthesized and membrane lipids orchestrate T cell biology. We also describe the roles of lipids as regulators of intracellular signaling at the levels of transcriptional, epigenetic and post-translational regulation in T cells. Finally, we summarize therapeutic targeting of lipid metabolism and signaling, and conclude with a discussion of important future directions. Understanding the molecular and functional interplay between lipid metabolism and T cell biology will ultimately inform therapeutic intervention for human disease.

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.