IL-25 stimulates M2 macrophage polarization and thereby promotes mitochondrial respiratory capacity and lipolysis in adipose tissues against obesity

Systematic pharmacology and experimental validation to elucidate the inflammation-associated mechanism of Huanglian Wendan (HLWD) decoction in the treatment of MAFLD associated with atherosclerosis

ETHNOPHARMACOLOGICAL RELEVANCE

Metabolic-associated fatty liver disease (MAFLD) and atherosclerosis are very common disorders that frequently coexist. The therapeutic efficacy of Huanglian Wendan (HLWD) decoction, a traditional Chinese medicine (TCM) prescription, is satisfactory in treating MAFLD associated with atherosclerosis. However, the underlying mechanisms through which HLWD exerts its effects need to be elucidated. Given the complex composition of HLWD and its multiple therapeutic targets, pharmacological investigation is challenging.

AIM OF THIS STUDY

This study aimed to identify the effective compounds in HLWD and elucidate the mechanisms involved in its therapeutic effect on MAFLD associated with atherosclerosis.

MATERIALS AND METHODS

We used a systematic pharmacology method to identify effective compounds present in HLWD and determine the mechanism by which it affects MAFLD associated with atherosclerosis. The effective components of HLWD were identified through ultrahigh-performance liquid chromatography-q exactive-orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). Next, a comprehensive in silico method was used to predict potential related targets and disease targets for these compounds to establish corresponding pathways. The accuracy of our assumed systemic pharmacology results was determined by conducting follow-up experiments.

RESULTS

By conducting UHPLC-Q-Orbitrap HRMS combined with network analysis, we identified 18 potentially active components of HLWD and assessed the inflammatory regulatory mechanism by which it affects MAFLD associated with atherosclerosis on the basis of 52 key targets. We used a high-fat, high-cholesterol (HFHC)-induced mice model of MAFLD associated with atherosclerosis to confirm our results. We found that administering HLWD significantly improved the appearance of their liver and reduced their body weight, liver weight, blood lipids, hepatic damage, and hepatic pathology. HLWD also decreased atherosclerotic lesion areas, foam cells, and inflammatory cells in the aorta. HLWD showed anti-inflammatory effects, suppressed M1 polarization, and promoted M2 polarization in the liver and aorta. HLWD might also regulate peroxisome proliferator-activated receptor-γ (PPARγ)/nuclear factor kappa-B (NF-κB) signaling to influence macrophage polarization and inflammation.

CONCLUSIONS

Our results showed that HLWD protected against HFHC diet-induced MAFLD associated with atherosclerosis by regulating PPARγ/NF-κB signaling, thus adjusting macrophage polarization and inflammation. Additionally, pharmacochemistry research, network pharmacology analysis, and experimental verification can be combined to form a comprehensive model used in studies on TCM.

Predicting steroid-induced osteonecrosis of the femoral head: role of lipid metabolism biomarkers and radiomics in young and middle-aged adults

BACKGROUND

Femoral head necrosis is a common orthopedic disease that results in significant physical disability in patients. Early prediction and diagnosis of steroid-induced osteonecrosis of the femoral head (SONFH) are crucial for the prevention and treatment of this condition.

METHODS

In this study, initial CT images and clinical data of patients with SONFH, admitted from January 2019 to December 2022, were collected. Patients were grouped as follows: (1) those diagnosed with SONFH at the initial diagnosis (control group), and (2) those with high-risk factors but no symptoms at first diagnosis, who developed SONFH two years later (experimental group). CT imaging histological features, clinical characteristics, and transcriptome screening for differentially expressed genes, pathway enrichment, and immune infiltration analyses were performed.

RESULTS

Significant differences were found in triglyceride (TG) levels between the training and validation groups. Age, sex, alkaline phosphatase (ALP), and hemoglobin levels differed between the training and internal validation groups, while HDL and red blood cell counts varied between the training and external validation groups. Univariate analysis showed that age, TG, HDL, and Radiomics scores influenced SONFH, while multivariate analysis revealed TG, HDL, and Radiomics scores were closely related to SONFH. Transcriptomic analysis showed associations with sphingolipid and adipocyte signaling pathways, along with immune cell involvement, linking SONFH to lipid metabolism and atherosclerosis.

CONCLUSIONS

These findings indicate a significant association between steroid-induced osteonecrosis of the femoral head and age, with TG and HDL serving as indicators of lipid metabolism closely correlated with the occurrence of SONFH. Radiomics scores were also found to correlate with SONFH occurrence, supported by transcriptomic and CT imaging findings. However, this study has limitations, including its retrospective design and a relatively limited sample size, which may impact the generalizability of the results. Further prospective studies with larger, more diverse populations are needed to validate and enhance the predictive model.

Gene therapy for fat-1 prevents obesity-induced metabolic dysfunction, cellular senescence, and osteoarthritis

Obesity is one of the primary risk factors for osteoarthritis (OA), acting through cross talk among altered biomechanics, metabolism, adipokines, and dietary free fatty acid (FA) composition. Obesity and aging have been linked to cellular senescence in various tissues, resulting in increased local and systemic inflammation and immune dysfunction. We hypothesized that obesity and joint injury lead to cellular senescence that is typically associated with increased OA severity or with aging and that the ratio of omega-6 (ω-6) to omega-3 (ω-3) FAs regulates these pathologic effects. Mice were placed on an ω-6-rich high-fat diet or a lean control diet and underwent destabilization of the medial meniscus to induce OA. Obesity and joint injury significantly increased cellular senescence in subcutaneous and visceral fat as well as joint tissues such as synovium and cartilage. Using adeno-associated virus (AAV) gene therapy for fat-1, a fatty acid desaturase that converts ω-6 to ω-3 FAs, decreasing the serum ω-6:ω-3 FA ratio had a strong senomorphic and therapeutic effect, mitigating metabolic dysfunction, cellular senescence, and joint degeneration. In vitro coculture of bone marrow-derived macrophages and chondrocytes from control and AAV8-fat1-treated mice were used to examine the roles of various FA mediators in regulating chondrocyte senescence. Our results suggest that obesity and joint injury result in a premature "aging" of the joint as measured by senescence markers, and these changes can be ameliorated by altering FA composition using fat-1 gene therapy. These findings support the potential for fat-1 gene therapy to treat obesity- and/or injury-induced OA clinically.

Trained immunity of intestinal tuft cells during infancy enhances host defense against enteroviral infections in mice

Innate immune cells have been acknowledged as trainable in recent years. While intestinal tuft cells are recognized for their crucial roles in the host defense against intestinal pathogens, there remains uncertainty regarding their trainability. Enterovirus 71 (EV71), a prevalent enterovirus that primarily infects children but rarely infects adults. At present, there is a significant expansion of intestinal tuft cells in the EV71-infected mouse model, which is associated with EV71-induced interleukin-25 (IL-25) production. Further, we found that IL-25 pre-treatment at 2 weeks old mouse enabled tuft cells to acquire immune memory. This was evidenced by the rapid expansion and stronger response of IL-25-trained tuft cells in response to EV71 infection at 6 weeks old, surpassing the reactivity of naïve tuft cells in mice without IL-25-trained progress. Interestingly, IL-25-trained intestinal tuft cells exhibit anti-enteroviral effect via producing a higher level of IL-25. Mechanically, IL-25 treatment upregulates spermidine/spermine acetyl-transferase enzyme (SAT1) expression, mediates intracellular polyamine deficiency, further inhibits enterovirus replication. In summary, tuft cells can be trained by IL-25, which supports faster and higher level IL-25 production in response to EV71 infection and further exhibits anti-enteroviral effect via SAT1-mediated intracellular polyamine deficiency. Given that IL-25 can be induced by multiple gut microbes during human growth and development, including shifts in gut flora abundance, which may partially explain the different susceptibility to enteroviral infections between adults and children.

Legumain-deficient macrophages regulate inflammation and lipid metabolism in adipose tissues to protect against diet-induced obesity

Adipose tissue macrophages (ATMs) are key players in the development of obesity and associated metabolic inflammation, which contributes to systemic metabolic dysfunction, and understanding the interaction between macrophages and adipocytes is crucial for developing novel macrophage-based strategies against obesity. Here, we found that Legumain (Lgmn), a well-known lysosomal cysteine protease, is expressed mainly in the ATMs of obese mice. To further define the potential role of Lgmn-expressing macrophages in the generation of an aberrant metabolic state, LgmnF/F; LysMCre mice, which do not express Lgmn in macrophages, were maintained on a high-fat diet (HFD), and metabolic parameters were assessed. Macrophage-specific Lgmn deficiency protects mice against HFD-induced obesity, diminishes the quantity of proinflammatory macrophages in obese adipose tissues, and alleviates hepatic steatosis and insulin resistance. By analysing the transcriptome and proteome of murine visceral white adipose tissue (vWAT) after HFD feeding, we determined that macrophage Lgmn deficiency causes changes in lipid metabolism and the inflammatory response. Furthermore, the reciprocity of macrophage-derived Lgmn with integrin α5β1 in adipocytes was tested via colocalization analyses. It is further demonstrated in macrophage and adipocyte coculture system that macrophage derived Lgmn bound to integrin α5β1 in adipocytes, therefore attenuating PKA activation, downregulating lipolysis-related proteins and eventually exacerbating obesity development. Overall, our study identified Lgmn as a previously unrecognized regulator involved in the interaction between ATMs and adipocytes contributing to diet-induced obesity and suggested that Lgmn is a potential target for treating metabolic disorders.

Cell-cell crosstalk between fat cells and immune cells

Obesity is a metabolic disorder with pandemic-like implications, lacking viable pharmaceutical treatments currently. Thermogenic adipose tissues, including brown and beige adipose tissues, play an essential role in regulating systemic energy homeostasis and have emerged as appealing therapeutic targets for the treatment of obesity and obesity-related diseases. The function of adipocytes is subject to complex regulation by a cellular network of immune signaling pathways in response to environmental signals. However, the specific regulatory roles of immune cells in thermogenesis and relevant involving mechanisms are still not well understood. Here, we concentrate on our present knowledge of the interaction between thermogenic adipocytes and immune cells and present an overview of cellular and molecular mechanisms underlying immunometabolism in adipose tissues. We discuss cytokines, especially interleukins, which originate from widely variable sources, and their impacts on the development and function of thermogenic adipocytes. Moreover, we summarize the neuroimmune regulation in heat production and expand a new mode of intercellular communication mediated by mitochondrial transfer. The crosstalk between immune cells and adipocytes achieves adipose tissue homeostasis and systemic energy balance. A deep understanding of this intricate interaction would provide evidence for improving thermogenic efficiency by remodeling the immune microenvironment. Interventions based on these factors show a high potential to prevent adverse metabolic outcomes in patients with obesity.

Obesity-induced chronic low-grade inflammation in adipose tissue: A pathway to Alzheimer's disease

Alzheimer's disease (AD) is a leading cause of cognitive impairment worldwide. Overweight and obesity are strongly associated with comorbidities, such as hypertension, diabetes, and insulin resistance (IR), which contribute substantially to the development of AD and subsequent morbidity and mortality. Adipose tissue (AT) is a highly dynamic organ composed of a diverse array of cell types, which can be classified based on their anatomic localization or cellular composition. The expansion and remodeling of AT in the context of obesity involves immunometabolic and functional shifts steered by the intertwined actions of multiple immune cells and cytokine signaling within AT, which contribute to the development of metabolic disorders, IR, and systemic markers of chronic low-grade inflammation. Chronic low-grade inflammation, a prolonged, low-dose stimulation by specific immunogens that can progress from localized sites and affect multiple organs throughout the body, leads to neurodystrophy, increased apoptosis, and disruption of homeostasis, manifesting as brain atrophy and AD-related pathology. In this review, we sought to elucidate the mechanisms by which AT contributes to the onset and progression of AD in obesity through the mediation of chronic low-grade inflammation, particularly focusing on the roles of adipokines and AT-resident immune cells.

Interleukin 25 promotes muscle regeneration in sarcopenia by regulating macrophage-mediated Sonic Hedgehog signaling

OBJECTIVE

Sarcopenia manifests as a chronic, low-level inflammation along with multiple inflammatory cells infiltration. Interleukin (IL)-25 can regulate the function of macrophages. However, the specific role and mechanisms through which IL-25 functions in sarcopenia are still not fully understood and require further investigation.

METHODS

Aged mice were utilized as sarcopenia models and examined the expression of inflammatory factors. To investigate the effects of IL-25 on sarcopenia, the model mice received IL-25 treatment and underwent in vivo adoptive transfer of IL-25-induced macrophages. Meanwhile, RAW264.7 cells, bone marrow-derived macrophages, satellite cells and C2C12 cells were used in vitro. Shh insufficiency was induced through intramuscular administration of SHH-shRNA adenoviruses. Then, various assays including scratch wound, cell counting kit-8 and Transwell assays, as well as histological staining and molecular biological methods, were conducted.

RESULTS

Aged mice exhibited an accelerated decline in muscle strength and mass, along with an increased muscle lipid droplets and macrophage infiltration, and decreased IL-25 levels compared to the young group. IL-25 therapy and the transfer of IL-25-preconditioned macrophages could improve these conditions by promoting M2 macrophage polarization in vivo as well as in vitro. M2 macrophage conditioned medium enhanced satellite cell proliferation and migration, as well as the vitality, migration, and differentiation of C2C12 cells in vitro. Furthermore, IL-25 enhanced Shh expression in macrophages in vitro, and activated the Shh signaling pathway in muscle tissue of aged mice, which could be suppressed by either the inhibitor cyclopamine or Shh knockdown. Mechanistic studies showed that Shh insufficiency suppressed the activation of Akt/mTOR signaling pathway in muscle tissue of aged mice.

CONCLUSION

IL-25 promotes the secretion of Shh by M2 macrophages and activates the Shh/Akt/mTOR signaling pathway, which improves symptoms and function in sarcopenia mice. This suggests that IL-25 has potential as a therapeutic agent for treating sarcopenia.

The significance of lipid metabolism reprogramming of tumor-associated macrophages in hepatocellular carcinoma

In the intricate landscape of the tumor microenvironment, tumor-associated macrophages (TAMs) emerge as a ubiquitous cellular component that profoundly affects the oncogenic process. The microenvironment of hepatocellular carcinoma (HCC) is characterized by a pronounced infiltration of TAMs, underscoring their pivotal role in modulating the trajectory of the disease. Amidst the evolving therapeutic paradigms for HCC, the strategic reprogramming of metabolic pathways presents a promising avenue for intervention, garnering escalating interest within the scientific community. Previous investigations have predominantly focused on elucidating the mechanisms of metabolic reprogramming in cancer cells without paying sufficient attention to understanding how TAM metabolic reprogramming, particularly lipid metabolism, affects the progression of HCC. In this review article, we intend to elucidate how TAMs exert their regulatory effects via diverse pathways such as E2F1-E2F2-CPT2, LKB1-AMPK, and mTORC1-SREBP, and discuss correlations of TAMs with these processes and the characteristics of relevant pathways in HCC progression by consolidating various studies on TAM lipid uptake, storage, synthesis, and catabolism. It is our hope that our summary could delineate the impact of specific mechanisms underlying TAM lipid metabolic reprogramming on HCC progression and provide useful information for future research on HCC and the development of new treatment strategies.

Macrophage polarization: an important role in inflammatory diseases

Macrophages are crucial cells in the human body's innate immunity and are engaged in a variety of non-inflammatory reactions. Macrophages can develop into two kinds when stimulated by distinct internal environments: pro-inflammatory M1-like macrophages and anti-inflammatory M2-type macrophages. During inflammation, the two kinds of macrophages are activated alternatively, and maintaining a reasonably steady ratio is critical for maintaining homeostasis in vivo. M1 macrophages can induce inflammation, but M2 macrophages suppress it. The imbalance between the two kinds of macrophages will have a significant impact on the illness process. As a result, there are an increasing number of research being conducted on relieving or curing illnesses by altering the amount of macrophages. This review summarizes the role of macrophage polarization in various inflammatory diseases, including autoimmune diseases (RA, EAE, MS, AIH, IBD, CD), allergic diseases (allergic rhinitis, allergic dermatitis, allergic asthma), atherosclerosis, obesity and type 2 diabetes, metabolic homeostasis, and the compounds or drugs that have been discovered or applied to the treatment of these diseases by targeting macrophage polarization.

The molecular mechanism of macrophage-adipocyte crosstalk in maintaining energy homeostasis

Interactions between macrophages and adipocytes in adipose tissue are critical for the regulation of energy metabolism and obesity. Macrophage polarization induced by cold or other stimulations can drive metabolic reprogramming of adipocytes, browning, and thermogenesis. Accordingly, investigating the roles of macrophages and adipocytes in the maintenance of energy homeostasis is critical for the development of novel therapeutic approaches specifically targeting macrophages in metabolic disorders such as obesity. Current review outlines macrophage polarization not only regulates the release of central nervous system and inflammatory factors, but controls mitochondrial function, and other factor that induce metabolic reprogramming of adipocytes and maintain energy homeostasis. We also emphasized on how the adipocytes conversely motivate the polarization of macrophage. Exploring the interactions between adipocytes and macrophages may provide new therapeutic strategies for the management of obesity-related metabolic diseases.

Prepared Radix Polygoni Multiflori and emodin alleviate lipid droplet accumulation in nonalcoholic fatty liver disease through MAPK signaling pathway inhibition

As one of the most common liver diseases, nonalcoholic fatty liver disease (NAFLD) affects almost one-quarter of the world's population. Although the prevalence of NAFLD is continuously rising, effective medical treatments are still inadequate. Radix Polygoni Multiflori (RPM) is a traditional Chinese herbal medicine. As a processed product of RPM, prepared Radix Polygoni Multiflori (PRPM) has been reported to have antioxidant and anti-inflammatory effects. This study investigated whether PRPM treatment could significantly improve NAFLD. We used recent literature, the Herb database and the SwissADME database to isolate the active compounds of PRPM. The OMIM, DisGeNET and GeneCards databases were used to isolate NAFLD-related target genes, and GO functional enrichment and KEGG pathway enrichment analyses were conducted. Moreover, PRPM treatment in NAFLD model mice was evaluated. The results indicate that the target genes are mainly enriched in the AMPK and de novo lipogenesis signaling pathways and that PRPM treatment improves NAFLD disease in model mice. Here, we found the potential benefits of PRPM against NAFLD and demonstrated in vivo and in vitro that PRPM and its ingredient emodin downregulate phosphorylated P38/P38, phosphorylated ERK1/2 and genes related to de novo adipogenesis signaling pathways and reduce lipid droplet accumulation. In conclusion, our findings revealed a novel therapeutic role for PRPM in the treatment of NAFLD and metabolic inflammation.

Possible connection between intestinal tuft cells, ILC2s and obesity

Intestinal tuft cells (TCs) are defined as chemosensory cells that can "taste" danger and induce immune responses. They play a critical role in gastrointestinal parasite invasion, inflammatory bowel diseases and high-fat diet-induced obesity. Intestinal IL-25, the unique product of TCs, is a key activator of type 2 immunity, especially to promote group 2 innate lymphoid cells (ILC2s) to secret IL-13. Then the IL-13 mainly promotes intestinal stem cell (ISCs) proliferation into TCs and goblet cells. This pathway formulates the circuit in the intestine. This paper focuses on the potential role of the intestinal TC, ILC2 and their circuit in obesity-induced intestinal damage, and discussion on further study and the potential therapeutic target in obesity.

DHA alleviated hepatic and adipose inflammation with increased adipocyte browning in high-fat diet-induced obese mice

Obesity is associated with accumulation of inflammatory immune cells in white adipose tissue, whereas thermogenic browning adipose tissue is inhibited. Dietary fatty acids are important nutritional components and several clinical and experimental studies have reported beneficial effects of docosahexaenoic acid (DHA) on obesity-related metabolic changes. In this study, we investigated effects of DHA on hepatic and adipose inflammation and adipocyte browning in high-fat diet-induced obese C57BL/6J mice, and in vitro 3T3-L1 preadipocyte differentiation. Since visceral white adipose tissue has a close link with metabolic abnormality, epididymal adipose tissue represents current target for evaluation. A course of 8-week DHA supplementation improved common phenotypes of obesity, including improvement of insulin resistance, inhibition of macrophage M1 polarization, and preservation of macrophage M2 polarization in hepatic and adipose tissues. Moreover, dysregulated adipokines and impaired thermogenic and browning molecules, considered obesogenic mechanisms, were improved by DHA, along with parallel alleviation of endoplasmic reticulum (ER) stress, mitochondrial dysfunction, and mitochondrial DNA stress-directed innate immunity. During 3T3-L1 preadipocytes differentiation, DHA treatment decreased lipid droplet accumulation and increased the levels of thermogenic, browning, and mitochondrial biogenesis molecules. Our study provides experimental evidence that DHA mitigates obesity-associated inflammation and induces browning of adipose tissue in visceral epididymal adipose tissue. Since obesity is associated with metabolic abnormalities across tissues, our findings indicate that DHA may have potential as part of a dietary intervention to combat obesity.

A Newly Synbiotic Combination Alleviates Obesity by Modulating the Gut Microbiota-Fat Axis and Inhibiting the Hepatic TLR4/NF-κB Signaling Pathway

SCOPE

Obesity has been recognized as a worldwide public health crisis, this is accompanied by dysregulation of the intestinal microbiota and upregulation of liver steatosis and adipose inflammation. Synbiotic as a novel alternative therapy for obesity have recently gained much attention.

METHODS

This study innovatively research the anti-obesity properties of a newly synbiotic composed of Lactobacillus acidophilus, Bifidobacterium infantis and konjac glucomannan oligosaccharides.

RESULTS

The synbiotic treatment can reduce body weight, fat mass, blood sugar, liver steatosis and adipose inflammation in obesity mice fed by high-fat diet (HFD). Meanwhile, synbiotic treatment activated brown adipose tissue and improve energy, glucose and lipid metabolism. In addition, synbiotic treatment not solely enhanced the protection of intestinal barrier, but also ameliorated gut microbiota dysbiosis directly by enhancing beneficial microbes and reducing potentially harmful bacteria. Furthermore, the microbiome phenotype and functional prediction showed that synbiotic treatment can improve the gut microbiota functions involving inflammatory state, immune response, metabolism and pathopoiesia.

CONCLUSION

The synbiotic may be an effective candidate treatment strategy for the clinical prevention and treatment of obesity and other associated metabolic diseases such as hyperlipidemia, nonalcoholic fatty liver diseases by alleviating inflammatory response, regulating energy metabolism and maintaining the balance of intestinal microecology.

CD36-SREBP1 Axis Mediates TSLP Production in Obesity-Exacerbated Atopic Dermatitis

Obesity is associated with an increased risk of atopic dermatitis (AD) and may accelerate its development. Keratinocyte dysfunction has been observed in obesity-related skin diseases, including psoriasis and acanthosis nigricans, but is not fully understood in AD. In this study, we found that high-fat diet-induced obesity exacerbated AD-like dermatitis in mice, with elevated inflammatory molecules and increased CD36-SREBP1-related fatty acid accumulation in the lesional skin. Blocking CD36 or SREBP1 with chemical inhibitors effectively alleviated AD-like inflammation, decreased fatty acid accumulation, and downregulated TSLP expression in obese calcipotriol (MC903)-treated mice. Moreover, palmitic acid treatment induced TSLP overexpression in keratinocytes through the activation of the CD36-SREBP1 signaling pathway. The chromatin immunoprecipitation assay further revealed increased binding of SREBP1 to the TSLP promoter region. Our findings provide compelling evidence that obesity triggers the activation of the CD36-SREBP1-TSLP axis in keratinocytes, leading to epidermal lipid disorders and the aggravation of AD-like inflammation. By targeting CD36 or SREBP1, future combination therapies or modified treatment strategies could be developed to help manage patients with both obesity and AD.

Myeloid BAF60a deficiency alters metabolic homeostasis and exacerbates atherosclerosis

Atherosclerosis, a leading health concern, stems from the dynamic involvement of immune cells in vascular plaques. Despite its significance, the interplay between chromatin remodeling and transcriptional regulation in plaque macrophages is understudied. We discovered the reduced expression of Baf60a, a component of the switch/sucrose non-fermentable (SWI/SNF) chromatin remodeling complex, in macrophages from advanced plaques. Myeloid-specific Baf60a deletion compromised mitochondrial integrity and heightened adhesion, apoptosis, and plaque development. BAF60a preserves mitochondrial energy homeostasis under pro-atherogenic stimuli by retaining nuclear respiratory factor 1 (NRF1) accessibility at critical genes. Overexpression of BAF60a rescued mitochondrial dysfunction in an NRF1-dependent manner. This study illuminates the BAF60a-NRF1 axis as a mitochondrial function modulator in atherosclerosis, proposing the rejuvenation of perturbed chromatin remodeling machinery as a potential therapeutic target.

PPARs/macrophages: A bridge between the inflammatory response and lipid metabolism in autoimmune diseases

Autoimmune diseases (AIDs) are a collection of pathologies that arise from autoimmune reactions and lead to the destruction and damage of the body's tissues and cellular components, ultimately resulting in tissue damage and organ dysfunction. The anti-inflammatory effects of the peroxisome proliferator-activated receptor (PPAR), a pivotal regulator of lipid metabolism, are crucial in the context of AIDs. PPAR mitigates AIDs by modulating macrophage polarization and suppressing the inflammatory response. Numerous studies have demonstrated the crucial involvement of lipid metabolism and phenotypic switching in classically activated (M1)/alternatively activated (M2)-like macrophages in the inflammatory pathway of AIDs. However, the precise mechanism by which PPAR, a critical mediator between of lipid metabolism and macrophage polarization, regulates macrophage polarization remains unclear. This review aimed to clarify the role of PPAR and macrophages in the triangular relationship among AIDs, lipid metabolism, and inflammatory response, and aims to summarize the mechanism of the PPAR-mediated macrophage activation and polarization, which impacts the progression and development of AIDs.

Exosomes-regulated lipid metabolism in tumorigenesis and cancer progression

Increasing evidence highlights the role of lipid metabolism in tumorigenesis and tumor progression. Targeting the processes of lipid metabolism, including lipogenesis, lipid uptake, fatty acid oxidation, and lipolysis, is an optimal strategy for anti-cancer therapy. Beyond cell-cell membrane surface interaction, exosomes are pivotal factors that transduce intercellular signals in the tumor microenvironment (TME). Most research focuses on the role of lipid metabolism in regulating exosome biogenesis and extracellular matrix (ECM) remodeling. The mechanisms of exosome and ECM-mediated reprogramming of lipid metabolism are currently unclear. We summarize several mechanisms associated with the regulation of lipid metabolism in cancer, including transport of exosomal carriers and membrane receptors, activation of the PI3K pathway, ECM ligand-receptor interactions, and mechanical stimulation. This review aims to highlight the significance of these intercellular factors in TME and to deepen the understanding of the functions of exosomes and ECM in the regulation of lipid metabolism.

Sitosterol-rich Digera muricata against 7-ketocholesterol and lipopolysaccharide-mediated atherogenic responses by modulating NF-ΚB/iNOS signalling pathway in macrophages

Digera muricata L., commonly known as Tartara, is an edible herb used as traditional medicine in many countries of Africa and Asia. This study aimed to elucidate the effect of a phytosterol-rich extract of D. muricata on 7-ketocholesterol-mediated atherosclerosis in macrophages. The extract was examined by phytochemical analyses, GC-MS, TLC, DPPH scavenging and hRBC membrane stabilization assays. Macrophage polarization was studied with experimental groups framed based on alamar blue cell viability and griess assays. Regulations of arginase enzyme activity, ROS generation, mitochondrial membrane potential, cell membrane integrity, pinocytosis, lipid uptake and peroxidation, as well as, intracellular calcium deposition were determined. In addition, expressions of atherogenic mediators were analysed using PCR, ELISA and immunocytochemistry techniques. Diverse phytochemicals with higher free radical scavenging activity and anti-inflammatory potential have been detected in the D. muricata. Co-treatment with D. muricata markedly reduced the atherogenic responses induced by 7KCh in the presence of LPS such as ROS, especially, NO and O2- along with lipid peroxidation. Furthermore, D. muricata significantly normalized mitochondrial membrane potential, cell membrane integrity, pinocytic activity, intracellular lipid accumulation and calcium deposition. These results provided us with the potentiality of D. muricata in ameliorating atherogenesis. Additionally, it decreased the expression of pro-atherogenic mediators (iNOS, COX-2, MMP9, IL-6, IL-1β, CD36, CD163 and TGFβ1) and increased anti-atherogenic mediators (MRC1 and PPARγ) with high cellular expressions of NF-κB and iNOS. Results showed the potential of sitosterol-rich D. muricata as a versatile biomedical therapeutic agent against abnormal macrophage polarization and its associated pathologies.

Lipid Metabolism Reprogramming of Immune Cells in Acne: An Update

Acne vulgaris is one of the most widespread skin conditions and the main reason for visiting a dermatologist. Inflammatory response and abnormal infiltrations of immune cells are the main pathogenesis of acne. The increased lipid is the prerequisite for the acne, and the perturbation of lipid composition and content is consistent with the severity of acne. Furthermore, the increased lipid production not only contributes to the occurrence and development of acne, but also sensitizes the function of immune cells. The lipid metabolic dysfunction aggravates the severity of local tissue and provides pro-inflammatory-cytokine cues, which indicates the crucial roles of lipid metabolism on immune cells. Recent advances have demonstrated the lipid metabolism reprogramming of various immune cells in acne lesion. The abnormal lipid accumulation, lipolysis, and fatty acid oxidation lead to the activation and differentiation of immune cells, which promotes the pro-inflammatory cytokines production. Thus, this review discusses the emerging role of lipid metabolism reprogramming of immune cells in the progress of acne and aims to constitute food for others' projects involved in acne research.

Apocynin alleviates weight gain and obesity-induced adipose tissue inflammation in high-fat diet-fed C57BL/6 mice

Obesity involves chronic low-grade inflammation within adipose tissue. Apocynin (APO) is a therapeutic agent for the treatment of inflammatory diseases. Therefore, the present study aimed to investigate whether APO can reduce weight gain and obesity-induced adipose tissue inflammation. C57BL/6 mice were administered APO or orlistat (Orli) as a positive control with a high-fat diet (HFD) for 12 weeks. Lipopolysaccharide-stimulated 3T3-L1 adipocytes were used for the in vitro study. Our results showed a significantly lower white adipose tissue (WAT) mass index in 10 mg/kg APO-treated mice than in 20 mg/kg Orli-treated mice. Moreover, the protein expression of adipose triglyceride lipase, fatty acid synthase, sterol regulatory element-binding transcription factor 1, and peroxisome proliferator-activated receptor γ was reversed in the WAT of 10 mg/kg APO-treated mice. Furthermore, APO reduced the expression of the macrophage marker F4/80, decreased the mRNA levels of tumor necrosis factor-α and monocyte chemoattractant protein-1, and increased the mRNA levels of interleukin-10 in WAT. APO decreased the phosphorylation of c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p65 in vivo and in vitro. Notably, APO had a stronger effect on the amelioration of adipose tissue inflammation than Orli did. Our findings lay the foundation for research on the use of APO as an agent to ameliorate weight gain and obesity-induced inflammatory diseases.

Tuft cells - the immunological interface and role in disease regulation

Tuft cells, also known as taste chemosensory cells, accumulate during parasite colonization or infection and have powerful immunomodulatory effects on substances that could be detrimental, as well as possible anti-inflammatory or antibacterial effects. Tuft cells are the primary source of interleukin (IL)-25. They trigger extra Innate lymphoid type-2 cells (ILC2) in the intestinal lamina propria to create cytokines (type 2); for instance, IL-13, which leads to an increase in IL-25. As tuft cells can produce biological effector molecules, such as IL-25 and eicosanoids involved in allergy (for example, cysteinyl leukotrienes and prostaglandin D₂) and the neurotransmitter acetylcholine. Following parasite infection, tuft cells require transient receptor potential cation channel subfamily M member 5 (TRPM5)-dependent chemosensation to produce responses. Secretory tuft cells provide a physical mucus barrier against the external environment and therefore have vital defensive roles against diseases by supporting tissue maintenance and repair. In addition to recent research on tuft cells, more studies are required to understand the distribution, cell turnover, molecular characteristics, responses in various species, involvement in immunological function across tissues, and most importantly, the mechanism involved in the control of various diseases.

CX3CR1hi macrophages sustain metabolic adaptation by relieving adipose-derived stem cell senescence in visceral adipose tissue

Adipose-derived stem cells (ASCs) drive healthy visceral adipose tissue (VAT) expansion via adipocyte hyperplasia. Obesity induces ASC senescence that causes VAT dysfunction and metabolic disorders. It is challenging to restrain this process by biological intervention, as mechanisms of controlling VAT ASC senescence remain unclear. We demonstrate that a population of CX3CR1^hi macrophages is maintained in mouse VAT during short-term energy surplus, which sustains ASCs by restraining their senescence, driving adaptive VAT expansion and metabolic health. Long-term overnutrition induces diminishment of CX3CR1^hi macrophages in mouse VAT accompanied by ASC senescence and exhaustion, while transferring CX3CR1^hi macrophages restores ASC reservoir and triggers VAT beiging to alleviate the metabolic maladaptation. Mechanistically, visceral ASCs attract macrophages via MCP-1 and shape their CX3CR1^hi phenotype via exosomes; these macrophages relieve ASC senescence by promoting the arginase1-eIF5A hypusination axis. These findings identify VAT CX3CR1^hi macrophages as ASC supporters and unravel their therapeutic potential for metabolic maladaptation to obesity.

Glucocorticoid activation of anti-inflammatory macrophages protects against insulin resistance

Insulin resistance (IR) during obesity is linked to adipose tissue macrophage (ATM)-driven inflammation of adipose tissue. Whether anti-inflammatory glucocorticoids (GCs) at physiological levels modulate IR is unclear. Here, we report that deletion of the GC receptor (GR) in myeloid cells, including macrophages in mice, aggravates obesity-related IR by enhancing adipose tissue inflammation due to decreased anti-inflammatory ATM leading to exaggerated adipose tissue lipolysis and severe hepatic steatosis. In contrast, GR deletion in Kupffer cells alone does not alter IR. Co-culture experiments show that the absence of GR in macrophages directly causes reduced phospho-AKT and glucose uptake in adipocytes, suggesting an important function of GR in ATM. GR-deficient macrophages are refractory to alternative ATM-inducing IL-4 signaling, due to reduced STAT6 chromatin loading and diminished anti-inflammatory enhancer activation. We demonstrate that GR has an important function in macrophages during obesity by limiting adipose tissue inflammation and lipolysis to promote insulin sensitivity.

New insights into the function of Interleukin-25 in disease pathogenesis

Interleukin-25 (IL-25), also known as IL-17E, is a cytokine belonging to the IL-17 family. IL-25 is abundantly expressed by Th2 cells and various kinds of epithelial cells. IL-25 is an alarm signal generated upon cell injury or tissue damage to activate immune cells through the interaction with IL-17RA and IL-17RB receptors. The binding of IL-25 to IL-17RA/IL-17RB complex not only initiates and maintains type 2 immunity but also regulates other immune cells (e.g., macrophages and mast cells) via various signaling pathways. It has been well-documented that IL-25 is critically involved in the development of allergic disorders (e.g., asthma). However, the roles of IL-25 in the pathogenesis of other diseases and the underlying mechanisms are still unclear. This review presents current evidence on the roles of IL-25 in cancers, allergic disorders, and autoimmune diseases. Moreover, we discuss the unanswered key questions underlying IL-25-mediated disease pathology, which will provide new insights into the targeted therapy of this cytokine in clinical treatment.

Synergy of antioxidant and M2 polarization in polyphenol-modified konjac glucomannan dressing for remodeling wound healing microenvironment

Effective skin wound healing and tissue regeneration remain a challenge. Excessive/chronic inflammation inhibits wound healing, leading to scar formation. Herein, we report a wound dressing composed of KGM-GA based on the natural substances konjac glucomannan (KGM) and gallic acid (GA) that accelerates wound healing without any additional drugs. An in vitro study showed that KGM-GA could not only stimulate macrophage polarization to the anti-inflammatory M2 phenotype but also decrease reactive oxygen species (ROS) levels, indicating excellent anti-inflammatory properties. Moreover, in vivo studies of skin wounds demonstrated that the KGM-GA dressing significantly improved wound healing by accelerating wound closure, collagen deposition, and angiogenesis. In addition, it was observed that KGM-GA regulated M2 polarization, reducing the production of intracellular ROS in the wound microenvironment, which was consistent with the in vitro experiments. Therefore, this study designed a multifunctional biomaterial with biological activity, providing a novel dressing for wound healing.

Capturing the multifaceted function of adipose tissue macrophages

Adipose tissue macrophages (ATMs) bolster obesity-induced metabolic dysfunction and represent a targetable population to lessen obesity-associated health risks. However, ATMs also facilitate adipose tissue function through multiple actions, including adipocyte clearance, lipid scavenging and metabolism, extracellular remodeling, and supporting angiogenesis and adipogenesis. Thus, high-resolution methods are needed to capture macrophages' dynamic and multifaceted functions in adipose tissue. Herein, we review current knowledge on regulatory networks critical to macrophage plasticity and their multifaceted response in the complex adipose tissue microenvironment.

Environmental endocrine disruptor Bisphenol A induces metabolic derailment and obesity via upregulating IL-17A in adipocytes

BACKGROUND

Bisphenol A (BPA), a ubiquitous environmental endocrine disruptor, has been extensively demonstrated to be associated with metabolic disorders, including obesity and type 2 diabetes mellitus. However, the underlying mechanism underpinning the environmental etiology of chronic metabolic disorders has not been sufficiently elucidated.

OBJECTIVES

This study is designed to explore the toxicological pathogenesis of chronic inflammation in BPA exposure during obesity.

METHODS

We investigated the role of IL-17A in the association of BPA exposure and obesity from human cross-sectional study to animal models, including genetically modified IL-17A^-/- mice.

RESULTS

Here, our work started from case-control observation that BPA exposure was significantly associated with risk of obesity (odds ratio = 4.72, 95%CI: 3.18 - 11.18, P < 0.01), metabolic disorder and levels of interleukin-17A (IL-17A) in human adipose (estimated changes β = 0.46, 95%CI: 0.15 - 1.01, P < 0.01) with bariatric surgery. Animal model fed with high-fat diet (HFD) confirmed that BPA exposure aggravated body weight gain and insulin resistance, concurrent with much heightened inflammatory responses in the adipose tissue including increase in IL-17A and macrophage polarization towards M1 stage. Genetically modified IL-17A ablated mice (IL-17A^-/-) showed reversed adipose tissue inflammation response, improved macrophage polarization homeostasis, along with insulin sensitivity in both HFD group alone or much more significantly the HFD + BPA group. Moreover, mediation analysis in human epidemiological investigation demonstrated that plasma IL-17A attributed up to 30.01% mediating role in the associations between BPA exposure and obesity risk.

DISCUSSION

This research paradigm from human to animal provides strong evidence for the elucidation of IL-17A moderating inflammation and insulin resistance in obesity. Such findings reiterate the obesogenic role of environmental endocrine disruptor BPA in metabolic disorders and unveils the potential toxicological mechanisms underpinning such effect.

Treatment with Interleukin-25 Suppresses Short-Term High-Fructose Diet-Induced Hepatic Gene Expression and Activities of Fatty Acid Synthesis Enzymes in Rats

This study aimed to investigate the effects of interleukin-25, which belongs to the interleukin-17 family, on short-term high-fructose diet-induced hepatic triacylglycerol accumulation. Rats were fed a high-starch (control) or high-fructose diet for 7 d, with or without intraperitoneal administration of recombinant interleukin-25 from days 3-7. Treatment with interleukin-25 significantly reduced the mRNA levels and activity of fatty acid synthesis enzymes and caused a nominal reduction in hepatic triacylglycerol levels in rats fed a high-fructose diet but not in those fed a control diet. Interleukin-25 treatment did not affect the mRNA levels of β-oxidation enzymes in either the control or fructose-fed rats. These results suggest that treatment with interleukin-25 suppresses short-term high-fructose diet-induced fatty acid synthesis and leads to the alleviation of triacylglycerol accumulation in the liver.

TSLP, IL-33, and IL-25: Not just for allergy and helminth infection

The release of cytokines from epithelial and stromal cells is critical for the initiation and maintenance of tissue immunity. Three such cytokines, thymic stromal lymphopoietin, IL-33, and IL-25, are important regulators of type 2 immune responses triggered by parasitic worms and allergens. In particular, these cytokines activate group 2 innate lymphoid cells, TH2 cells, and myeloid cells, which drive hallmarks of type 2 immunity. However, emerging data indicate that these tissue-associated cytokines are not only involved in canonical type 2 responses but are also important in the context of viral infections, cancer, and even homeostasis. Here, we provide a brief review of the roles of thymic stromal lymphopoietin, IL-33, and IL-25 in diverse immune contexts, while highlighting their relative contributions in tissue-specific responses. We also emphasize a biologically motivated framework for thinking about the integration of multiple immune signals, including the 3 featured in this review.

Evaluation of Cardiac Biomarkers and Expression Analysis of IL-1, IL-6, IL-10, IL-17, and IL-25 among COVID-19 Patients from Pakistan

Coronavirus disease 19 (COVID-19) is caused by viral infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Where upregulation of several important biomarkers and multiple organ dysfunction occurs, this study aimed to evaluate the association of cardiac biomarkers and CS induced acute lung damage with disease severity and mortality in survival of COVID-19 patients. A total of 500 COVID-19 patients with elevated cardiac biomarkers were studied for the analysis of myocardial abnormality through cardiac enzymes, inflammatory biomarkers, and the expression analysis of various cytokines, including IL-1, IL-6, IL-10, IL-17, and IL-25 genes. The elevation of various cardiac enzymes including LDH (87%), CK (78.4%), TNI (80.4%), CK-MB (83%), and D-dimer (80.8%) were found correlated (p < 0.001) with COVID-19 infection. Cardiac enzyme elevation was highly associated with an increased level of inflammatory biomarkers such as CRP (14.2%), SAA (11.4%) and erythrocyte sedimentation rate (ESR) (7.8%) (p = 0.001 for all). The quantitative expression analysis of IL-10, 1L-17, and 1L-25 were found to be high, while those of IL-1 and IL-6 were moderately elevated. The death-to-live ratio of COVID-19 patients was 457:43 indicating that the patients having elevated levels of both CKMB, D-dimer, CK and IL-1, IL-6, IL-10 and D-dimer, Troponin, CK and IL-1, IL-10 had high fatality rate (73% and 12% respectively). The current finding concludes that the evaluation of cardiac biomarkers with cytokine storm plays a significant role in COVID-19-associated anatomical organ damage, myocardial injury, and mortality. Physicians should pay special attention to cardiac biomarkers in patients with old age, inflammation, and comorbidities among COVID-19 infections.

The potential roles of interleukin-25 in infectious diseases

Interleukin-25 (IL-25), also known as IL-17E, is a recently identified cytokine of the IL-17 family. Numerous studies illustrated that the expression of IL-25 is regulated by multiple pathogens, including parasitic, viral, and bacterial infections. IL-25 has a dual function in infectious diseases. On the one hand, IL-25 activates type 2 immunity via the relevant cytokines, including IL-4, IL-5, and IL-13, which are associated with the development of pathogenic infection-related allergic diseases. On the other hand, IL-25 involves in the recruitment of group 2 innate lymphoid cells (ILC2) to enhanced T helper 2 (Th2) cell differentiation, which are important to the clearance of pathogens. However, the precise roles of IL-25 in infectious diseases remain largely unknown. Thus, the current review will shed light on the pivotal roles of IL-25 in infectious diseases.

A high preoperative serum IL-25 level is a negative prognosis predictor after liver resection for HBV-HCC

Objective

The aim of this study was to evaluate the association between preoperative IL-25 levels and HBV-HCC patient outcomes following liver surgery.

Methods

This study enrolled consecutive HCC patients that had undergone liver surgery from 2008 to 2015. Baseline patient clinical properties were assessed to establish predictors of postoperative overall survival and recurrence-free survival (OS and RFS, respectively) following liver resection. In addition, serum IL-25 levels were assessed via ELISA.

Results

Cox regression analyses revealed IL-25 levels to be independently related to the OS and RFS of 896 HBV-associated HCC patients. An optimal IL-25 cutoff level of 14.9 μg/ml was identified, with 206 patients in this cohort having IL-25 levels above this threshold. Both the OS and RFS of patients with an IL-25 level <14.9 μg/ml were significantly better after liver resection as compared to those of patients with higher preoperative levels of this cytokine (p < 0.05). Cox multivariate regression analyses revealed an IL-25 level ≥ 14.9 μg/L to be an independent predictor of poorer RFS and OS. A combination of IL-25 levels and tumor diameter may be an even more reliable predictor of OS.

Conclusions

IL-25 levels are independent predictors of postoperative survival within HCC patients undergoing liver resection.

IL-25 ameliorates acute cholestatic liver injury via promoting hepatic bile acid secretion

Cholestasis caused by bile secretion and excretion disorders is a serious manifestation of hepatopathy. Interleukin (IL)-25 is a member of the IL-17 cytokine family, which involves in mucosal immunity and type 2 immunity via its receptor-IL-17RB. Our previous studies have shown that IL-25 improves non-alcoholic fatty liver via stimulating M2 macrophage polarization and promotes development of hepatocellular carcinoma via alternative activation of macrophages. These hepatopathy are closely associated with cholestasis. However, whether IL-25 play an important role in cholestasis remains unclear. IL-25 treatment and IL-25 knockout (Il25^-/-) mice were injected intragastrically with α-naphthyl isothiocyanate (ANIT) to determine the biological association between IL-25 and cholestasis. Here, we found that IL-25 and IL-17RB decreased in ANIT-induced cholestatic mice. Il25^-/- mice showed exacerbated ANIT-induced parenchymal injury and IL-25 treatment significantly alleviated cholestatic liver injury induced by ANIT. We found that IL-25 reduced the level of hepatic total bile acids and increased the expression of multidrug resistance-associated protein 2 (MRP2) and multidrug resistance-associated protein 3 (MRP3) in liver. In conclusion, IL-25 exhibited a protective effect against ANIT-induced cholestatic liver injury in mice, which may be related to the regulation on bile acids secretion. These results provide a theoretical basis for the use of IL-25 in the treatment of cholestatic hepatopathy.

IL-25 directly modulates adipocyte function and inflammation through the regulation of adiponectin

OBJECTIVE

This study aimed to investigate the direct role of IL-25 in modulating adipocyte function during homeostasis and low-grade inflammation induced by lipopolysaccharide (LPS).

METHODS

The 3T3-L1 preadipocyte cell lines and primary cultures of adipose-derived stromal vascular precursor cells of wild-type and IL-17RB-deficient mice were used to determine the direct function of IL-25. The expression of IL-17RB in differentiating adipocyte was determined using real-time PCR and flow cytometry analysis. The effect of IL-25 on lipid accumulation, triglyceride content, lipolysis, glucose uptake, and adipokine expression in the mature adipocytes was evaluated. IL-25 modulating the expression of inflammatory cytokines in adipocytes induced by low dose LPS was determined using real-time PCR and ELISA.

RESULTS

The receptor for IL-25 was up-regulated during adipocyte differentiation and IL-25 directly modulated adipocyte function by reducing lipid accumulation and triglyceride concentration and enhancing lipolysis without affecting an insulin-stimulated glucose uptake. Interestingly, IL-25 induced adiponectin secretion through the PI3K/AKT signaling pathway. In 3T3-L1 adipocytes under low-grade inflammation, IL-25 attenuated the expression of IL-6 and CCL5 through the induction of adiponectin.

CONCLUSION

Our studies suggest that IL-25 directly regulates adipocyte function by maintaining the adiponectin level during homeostasis and by alleviating inflammatory response through the regulation of adiponectin during low-grade inflammation in adipocytes.

Obesity-Mediated Immune Modulation: One Step Forward, (Th)2 Steps Back

Over the past decades, the relationship between the immune system and metabolism has become a major research focus. In this arena of immunometabolism the capacity of adipose tissue to secrete immunomodulatory molecules, including adipokines, within the underlying low-grade inflammation during obesity brought attention to the impact obesity has on the immune system. Adipokines, such as leptin and adiponectin, influence T cell differentiation into different T helper subsets and their activation during immune responses. Furthermore, within the cellular milieu of adipose tissue nutrient availability regulates differentiation and activation of T cells and changes in cellular metabolic pathways. Upon activation, T cells shift from oxidative phosphorylation to oxidative glycolysis, while the differential signaling of the kinase mammalian target of rapamycin (mTOR) and the nuclear receptor PPARγ, amongst others, drive the subsequent T cell differentiation. While the mechanisms leading to a shift from the typical type 2-dominated milieu in lean people to a Th1-biased pro-inflammatory environment during obesity are the subject of extensive research, insights on its impact on peripheral Th2-dominated immune responses become more evident. In this review, we will summarize recent findings of how Th2 cells are metabolically regulated during obesity and malnutrition, and how these states affect local and systemic Th2-biased immune responses.

Maresin1 Protect Against Ferroptosis-Induced Liver Injury Through ROS Inhibition and Nrf2/HO-1/GPX4 Activation

Drugs, viruses, and chemical poisons stimulating live in a short period of time can cause acute liver injury (ALI). ALI can further develop into serious liver diseases such as cirrhosis and liver cancer. Therefore, how to effectively prevent and treat ALI has become the focus of research. Numerous studies have reported Maresin1 (MaR1) has anti-inflammatory effect and protective functions on organs. In the present study, we used d-galactosamine/lipopolysaccharide (D-GalN/LPS) to establish an ALI model, explored the mechanism of liver cells death caused by D-GalN/LPS, and determined the effect of MaR1 on D-GalN/LPS-induced ALI. In vivo experiments, we found that MaR1 and ferrostatin-1 significantly alleviated D-GalN/LPS-induced ALI, reduced serum alanine transaminase and aspartate transaminase levels, and improved the survival rate of mice. Meanwhile, MaR1 inhibited hepatocyte death, inhibited tissue reactive oxygen species (ROS) expression, reduced malondialdehyde (MDA), reduced glutathione (GSH), GSH/oxidized glutathione (GSSG), and iron content induced by D-GalN/LPS in mice. In addition, MaR1 inhibited ferroptosis-induced liver injury through inhibiting the release of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6. Subsequently, western blot showed that MaR1 improved the expression of nuclear factor E2-related factor 2(Nrf2)/heme oxygenase-1 (HO-1)/glutathione peroxidase 4 (GPX4). In vitro experiments, we found that MaR1 inhibited LPS-induced and erastin-induced cell viability reduction. Meanwhile, we found that MaR1 increased the MDA and GSH levels in cells. Western blot showed that MaR1 increased the expression level of Nrf2/HO-1/GPX4. Next, the Nrf2 was knocked down in HepG2 cells, and the results showed that the protective effect of MaR1 significantly decreased. Finally, flow cytometry revealed that MaR1 inhibited ROS production and apoptosis. Overall, our study showed MaR1 inhibited ferroptosis-induced liver injury by inhibiting ROS production and Nrf2/HO-1/GPX4 activation.

IL-25 improves diabetic wound healing through stimulating M2 macrophage polarization and fibroblast activation

BACKGROUND

Persistent chronic inflammation is one of the main pathogenic characteristics of diabetic wounds. The resolution of inflammation is important for wound healing and extracellular matrix (ECM) formation. Interleukin (IL)-25 can modulate the function of macrophage and fibroblast, but its role and mechanism of action in the treatment of diabetic wounds remain largely unclear.

METHODS

The mice were categorized into diabetic, diabetic + IL-25 and control groups. Human monocytic THP-1 cell line and human dermal fibroblast (HDF) were stimulated under different IL-25 conditions. Then, flow cytometry, real-time quantitative PCR (RT-qPCR), Western blot (WB), and immunofluorescence (IF) assays were carried out.

RESULTS

The mice in diabetes group (DG) had a slower wound healing rate, more severe inflammation, less blood vessels and more disordered collagen than those in control group (CG). Intradermal injection of IL-25 could improve these conditions. IL-25 promoted M2 macrophage polarization and fibroblast activation in DG and high-glucose environment. The phenomenon, which was dependent on PI3K/AKT/mTOR and TGF-β/SMAD signaling, could be blocked by LY294002 and LY2109761.

CONCLUSION

IL-25 may serve as a therapeutic target to improve wound healing in diabetic mice.

Interleukin-25-Mediated-IL-17RB Upregulation Promotes Cutaneous Wound Healing in Diabetic Mice by Improving Endothelial Cell Functions

Diabetic foot ulcer (DFU) frequently leads to non-traumatic amputation and finally even death. However, the mechanism of DFU is not fully understood. Interleukin 25 (IL-25), an alarmin cytokine that responds to tissue injury, has been reported to participate in tissue regeneration and maintaining glucose homeostasis. However, the role of IL-25 in diabetic wound healing remains unknown. Here, we showed that interleukin 17 receptor B (IL-17RB), the functional receptor of IL-25, was significantly inhibited in the wound skin of both diabetic patients with DFU and streptozotocin (STZ)-induced diabetic mice. Topical administration of recombinant IL-25 protein improved angiogenesis and collagen deposition in the wound bed and thus ameliorated delayed diabetic wound healing. IL-25 increased endothelial-specific CD31 expression in diabetic wounds and exogenous IL-25 protected endothelial cells from high glucose-impaired cell migration and tube formation in vitro. We further revealed that IL-25-mediated-IL-17RB signaling rescued the downregulation of Wnt/β-catenin pathway both in vivo in diabetic mice and in vitro in HUVECs and induced the phosphorylation of AKT and ERK 1/2 in HUVECs under high glucose conditions. This study defines a positive regulatory role of IL-25-mediated-IL-17RB signaling in diabetic wound healing and suggests that induction of IL-25-mediated-IL-17RB signaling may be a novel therapeutic strategy for treating poor healing diabetic wounds.

IL-25 Induced ROS-Mediated M2 Macrophage Polarization via AMPK-Associated Mitophagy

Interleukin (IL)-25 is a cytokine released by airway epithelial cells responding to pathogens. Excessive production of reactive oxygen species (ROS) leads to airway inflammation and remodeling in asthma. Mitochondria are the major source of ROS. After stress, defective mitochondria often undergo selective degradation, known as mitophagy. In this study, we examined the effects of IL-25 on ROS production and mitophagy and investigated the underlying mechanisms. The human monocyte cell line was pretreated with IL-25 at different time points. ROS production was measured by flow cytometry. The involvement of mitochondrial activity in the effects of IL-25 on ROS production and subsequent mitophagy was evaluated by enzyme-linked immunosorbent assay, Western blotting, and confocal microscopy. IL-25 stimulation alone induced ROS production and was suppressed by N-acetylcysteine, vitamin C, antimycin A, and MitoTEMPO. The activity of mitochondrial complex I and complex II/III and the levels of p-AMPK and the mitophagy-related proteins were increased by IL-25 stimulation. The CCL-22 secretion was increased by IL-25 stimulation and suppressed by mitophagy inhibitor treatment and PINK1 knockdown. The Th2-like cytokine IL-25 can induce ROS production, increase mitochondrial respiratory chain complex activity, subsequently activate AMPK, and induce mitophagy to stimulate M2 macrophage polarization in monocytes.

The roles of T cells in obese adipose tissue inflammation

Adipose tissue inflammation in obese patients can cause a series of metabolic diseases. There are a variety of immune cells in adipose tissue, and studies have shown that T cells are associated with adipose tissue inflammation. This review aims to describe the current understanding of the relationship between T cells and adipose tissue inflammation, with a focus on regulation by T cell subtypes. Studies have shown that Th1, Th17 and CD8+ T cells, which are important T cell subsets, can promote the development of adipose tissue inflammation, whereas Treg cells protect against inflammation, suggesting that targeting the mechanism by which T cell subtypes regulate adipose tissue inflammation is a potential therapeutic strategy for treating obesity. T cells play important roles in regulating obesity-associated adipose tissue inflammation, thus providing new research directions for the treatment of obesity. More studies are needed to clarify how T cell subtypes regulate adipose tissue inflammation to identify new treatments for obesity.

Mitochondrial MicroRNAs Contribute to Macrophage Immune Functions Including Differentiation, Polarization, and Activation

A subset of microRNA (miRNA) has been shown to play an important role in mitochondrial (mt) functions and are named MitomiR. They are present within or associated with mitochondria. Most of the mitochondrial miRNAs originate from the nucleus, while a very limited number is encoded by mtDNA. Moreover, the miRNA machinery including the Dicer and Argonaute has also been detected within mitochondria. Recent, literature has established a close relationship between miRNAs and inflammation. Indeed, specific miRNA signatures are associated with macrophage differentiation, polarization and functions. Nevertheless, the regulation of macrophage inflammatory pathways governed specifically by MitomiR and their implication in immune-mediated inflammatory disorders remain poorly studied. Here, we propose a hypothesis in which MitomiR play a key role in triggering macrophage differentiation and modulating their downstream activation and immune functions. We sustain this proposition by bioinformatic data obtained from either the human monocytic THP1 cell line or the purified mitochondrial fraction of PMA-induced human macrophages. Interestingly, 22% of the 754 assayed miRNAs were detected in the mitochondrial fraction and are either exclusively or highly enriched cellular miRNA. Furthermore, the in silico analysis performed in this study, identified a specific MitomiR signature associated with macrophage differentiation that was correlated with gene targets within the mitochondria genome or with mitochondrial pathways. Overall, our hypothesis and data suggest a previously unrecognized link between MitomiR and macrophage function and fate. We also suggest that the MitomiR-dependent control could be further enhanced through the transfer of mitochondria from donor to target cells, as a new strategy for MitomiR delivery.

Enteric Tuft Cells in Host-Parasite Interactions

Enteric tuft cells are chemosensory epithelial cells gaining attention in the field of host-parasite interactions. Expressing a repertoire of chemosensing receptors and mediators, these cells have the potential to detect lumen-dwelling helminth and protozoan parasites and coordinate epithelial, immune, and neuronal cell defenses against them. This review highlights the versatility of enteric tuft cells and sub-types thereof, showcasing nuances of tuft cell responses to different parasites, with a focus on helminths reflecting the current state of the field. The role of enteric tuft cells in irritable bowel syndrome, inflammatory bowel disease and intestinal viral infection is assessed in the context of concomitant infection with parasites. Finally, the review presents pertinent questions germane to understanding the enteric tuft cell and its role in enteric parasitic infections. There is much to be done to fully elucidate the response of this intriguing cell type to parasitic-infection and there is negligible data on the biology of the human enteric tuft cell—a glaring gap in knowledge that must be filled.

Type 2 Innate Lymphoid Cells: Protectors in Type 2 Diabetes

Type 2 innate lymphoid cells (ILC2) are the innate counterparts of Th2 cells and are critically involved in the maintenance of homeostasis in a variety of tissues. Instead of expressing specific antigen receptors, ILC2s respond to external stimuli such as alarmins released from damage. These cells help control the delicate balance of inflammation in adipose tissue, which is a determinant of metabolic outcome. ILC2s play a key role in the pathogenesis of type 2 diabetes mellitus (T2DM) through their protective effects on tissue homeostasis. A variety of crosstalk takes place between resident adipose cells and ILC2s, with each interaction playing a key role in controlling this balance. ILC2 effector function is associated with increased browning of adipose tissue and an anti-inflammatory immune profile. Trafficking and maintenance of ILC2 populations are critical for tissue homeostasis. The metabolic environment and energy source significantly affect the number and function of ILC2s in addition to affecting their interactions with resident cell types. How ILC2s react to changes in the metabolic environment is a clear determinant of the severity of disease. Treating sources of metabolic instability via critical immune cells provides a clear avenue for modulation of systemic homeostasis and new treatments of T2DM.

IL-25-induced shifts in macrophage polarization promote development of beige fat and improve metabolic homeostasis in mice

Beige fat dissipates energy and functions as a defense against cold and obesity, but the mechanism for its development is unclear. We found that interleukin (IL)-25 signaling through its cognate receptor, IL-17 receptor B (IL-17RB), increased in adipose tissue after cold exposure and β3-adrenoceptor agonist stimulation. IL-25 induced beige fat formation in white adipose tissue (WAT) by releasing IL-4 and IL-13 and promoting alternative activation of macrophages that regulate innervation and up-regulate tyrosine hydroxylase (TH) up-regulation to produce more catecholamine including norepinephrine (NE). Blockade of IL-4Rα or depletion of macrophages with clodronate-loaded liposomes in vivo significantly impaired the beige fat formation in WAT. Mice fed with a high-fat diet (HFD) were protected from obesity and related metabolic disorders when given IL-25 through a process that involved the uncoupling protein 1 (UCP1)-mediated thermogenesis. In conclusion, the activation of IL-25 signaling in WAT may have therapeutic potential for controlling obesity and its associated metabolic disorders.

Elucidating the interaction between maternal physical activity and circulating myokines throughout gestation: A scoping review

Physical activity (PA) during pregnancy provides both maternal and fetal health benefits. It has been theorized that myokines, peptides secreted by contracting skeletal muscle, may play an important mechanistic role in facilitating the health benefits obtained from prenatal exercise. The objective of this review was to synthesize the current literature on the relationship between maternal PA and myokine response. A search strategy was developed using the terms pregnancy, PA, IL-6, IL-10, IL-13, and TNF-α. A systematic search was completed in July 2020, in Medline, SPORTDiscus, EMBASE, CENTRAL, and in November 2020 for unpublished dissertations (grey literature; Proquest). Both human- and animal-based studies of any design were included, while commentaries and editorial articles were excluded. Data were extracted by two independent reviewers and summarized narratively. Data were thematically summarized based on the myokine and whether findings were from human or animal studies. Ten studies were included in this review. Findings from studies that examined IL-6, IL-10, and TNF-α suggest a trimester-specific interaction between PA and myokine levels; no studies evaluated IL-13. Future research should investigate the PA-myokine relationship throughout all stages of gestation.

Activation of GCN2 in macrophages promotes white adipose tissue browning and lipolysis under leucine deprivation

We have previously shown that leucine deprivation stimulates browning and lipolysis in white adipose tissue (WAT), which helps to treat obesity. Adipose tissue macrophages (ATMs) significantly influence WAT browning and lipolysis. However, it is unclear whether ATMs are involved in leucine deprivation-induced browning and lipolysis in WAT; the associated signals remain to be elucidated. Here, we investigated the role of ATMs and the possible mechanisms involved in WAT browning and lipolysis under leucine-deprivation conditions. In this study, macrophages were depleted in mice by injecting clodronate-liposomes (CLOD) into subcutaneous white adipose tissues. Then, mice lacking general control nonderepressible 2 kinase (GCN2), which is a sensor of amino acid starvation, specifically in Lyz2-expressing cells, were generated to investigate the changes in leucine deprivation-induced WAT browning and lipolysis. We found leucine deprivation decreased the accumulation and changed the polarization of ATMs. Ablation of macrophages by CLOD impaired WAT browning and lipolysis under leucine-deprivation conditions. Mechanistically, leucine deprivation activated GCN2 signals in macrophages. Myeloid-specific abrogation of GCN2 in mice blocked leucine deprivation-induced browning and lipolysis in WAT. Further analyses revealed that GCN2 activation in macrophages reduced the expression of monoamine oxidase A (MAOA), resulting in increased norepinephrine (NE) secretion from macrophages to adipocytes, and this resulted in enhanced WAT browning and lipolysis. Moreover, the injection of CL316,243, a β3-adrenergic receptor agonist, and inhibition of MAOA effectively increased the level of NE, leading to the enhancement of browning and lipolysis of WAT in myeloid GCN2 knockout mice under leucine deprivation. Collectively, our results demonstrate a novel function of GCN2 signals in macrophages, that is, regulating WAT browning and lipolysis under leucine deprivation. Our study provides important hints for possible treatment for obesity.

Amadis: A Comprehensive Database for Association Between Microbiota and Disease

The human gastrointestinal tract represents a symbiotic bioreactor that can mediate the interaction of the human host. The deployment and integration of multi-omics technologies have depicted a more complete image of the functions performed by microbial organisms. In addition, a large amount of data has been generated in a short time. However, researchers struggling to keep track of these mountains of information need a way to conveniently gain a comprehensive understanding of the relationship between microbiota and human diseases. To tackle this issue, we developed Amadis (http://gift2disease.net/GIFTED), a manually curated database that provides experimentally supported microbiota-disease associations and a dynamic network construction method. The current version of the Amadis database documents 20167 associations between 221 human diseases and 774 gut microbes across 17 species, curated from more than 1000 articles. By using the curated data, users can freely select and combine modules to obtain a specific microbe-based human disease network. Additionally, Amadis provides a user-friendly interface for browsing, searching and downloading. We hope it can serve as a useful and valuable resource for researchers exploring the associations between gastrointestinal microbiota and human diseases.