Amlexanox attenuates experimental autoimmune encephalomyelitis by inhibiting dendritic cell maturation and reprogramming effector and regulatory T cell responses

Amlexanox targeted inhibition of TBK1 regulates immune cell function to exacerbate DSS-induced inflammatory bowel disease

Amlexanox (ALX) is a small-molecule drug for the treatment of inflammatory, autoimmune, metabolic, and tumor diseases. At present, there are no studies on whether ALX has a therapeutic effect on inflammatory bowel disease (IBD). In this study, we used a mouse model of dextran sulfate sodium-induced colitis to investigate the effect of ALX-targeted inhibition of TBK1 on colitis. We found that the severity of colitis in mice was correlated with TBK1 expression. Notably, although ALX inhibited the activation of the TBK1-NF-κB/TBK1-IRF3 pro-inflammatory signaling pathway, it exacerbated colitis and reduced survival in mice. The results of drug safety experiments ruled out a relationship between this exacerbating effect and drug toxicity. In addition, ELISA results showed that ALX promoted the secretion of IL-1β and IFN-α, and inhibited the production of cytokines IL-6, TNF-α, IL-10, TGF-β, and secretory IgA. Flow cytometry results further showed that ALX promoted T-cell proliferation, activation, and differentiation, and thus played a pro-inflammatory role; also, ALX inhibited the generation of dendritic cells and the polarization of macrophages to M1 type, thus exerting anti-inflammatory effect. These data suggest that the regulation of ALX on the function of different immune cells is different, so the effect on the inflammatory response is bidirectional. In conclusion, our study demonstrates that simply inhibiting TBK1 in all immune cells is not effective for the treatment of colitis. Further investigation of the anti-inflammatory mechanism of ALX on dendritic cells and macrophages may provide a new strategy for the treatment of IBD.

Human microbiome-derived peptide affects the development of experimental autoimmune encephalomyelitis via molecular mimicry

BACKGROUND

Gut commensal microbiota has been identified as a potential environmental risk factor for multiple sclerosis (MS), and numerous studies have linked the commensal microorganism with the onset of MS. However, little is known about the mechanisms underlying the gut microbiome and host-immune system interaction.

METHODS

We employed bioinformatics methodologies to identify human microbial-derived peptides by analyzing their similarity to the MHC II-TCR binding patterns of self-antigens. Subsequently, we conducted a range of in vitro and in vivo assays to assess the encephalitogenic potential of these microbial-derived peptides.

FINDINGS

We analyzed 304,246 human microbiome genomes and 103 metagenomes collected from the MS cohort and identified 731 nonredundant analogs of myelin oligodendrocyte glycoprotein peptide 35-55 (MOG35-55). Of note, half of these analogs could bind to MHC II and interact with TCR through structural modeling of the interaction using fine-tuned AlphaFold. Among the 8 selected peptides, the peptide (P3) shows the ability to activate MOG35-55-specific CD4+ T cells in vitro. Furthermore, P3 shows encephalitogenic capacity and has the potential to induce EAE in some animals. Notably, mice immunized with a combination of P3 and MOG35-55 develop severe EAE. Additionally, dendritic cells could process and present P3 to MOG35-55-specific CD4+ T cells and activate these cells.

INTERPRETATION

Our data suggests the potential involvement of a MOG35-55-mimic peptide derived from the gut microbiota as a molecular trigger of EAE pathogenesis. Our findings offer direct evidence of how microbes can initiate the development of EAE, suggesting a potential explanation for the correlation between certain gut microorganisms and MS prevalence.

FUNDING

National Natural Science Foundation of China (82371350 to GY).

Cytosolic DNA sensors in neurodegenerative diseases: from physiological defenders to pathological culprits

Cytosolic DNA sensors are a group of pattern recognition receptors (PRRs) that vary in structures, molecular mechanisms, and origins but share a common function to detect intracellular microbial DNA and trigger the innate immune response like type 1 interferon production and autophagy. Cytosolic DNA sensors have been proven as indispensable defenders against the invasion of many pathogens; however, growing evidence shows that self-DNA misplacement to cytoplasm also frequently occurs in non-infectious circumstances. Accumulation of cytosolic DNA causes improper activation of cytosolic DNA sensors and triggers an abnormal autoimmune response, that significantly promotes pathological progression. Neurodegenerative diseases are a group of neurological disorders characterized by neuron loss and still lack effective treatments due to a limited understanding of pathogenesis. But current research has found a solid relationship between neurodegenerative diseases and cytosolic DNA sensing pathways. This review summarizes profiles of several major cytosolic DNA sensors and their common adaptor protein STING. It also discusses both the beneficial and detrimental roles of cytosolic DNA sensors in the genesis and progression of neurodegenerative diseases.

Amlexanox attenuates LPS-induced neuroinflammatory responses in microglial cells via inhibition of NF-κB and STAT3 signaling pathways

Amlexanox is an anti-inflammatory and anti-allergic agent used clinically for the treatment of aphthous ulcers, allergic rhinitis, and asthma. Recent studies have demonstrated that amlexanox, a selective inhibitor of IkB kinase epsilon (IKKε) and TANK-binding kinase 1 (TBK1), suppresses a range of diseases or inflammatory conditions, such as obesity-related metabolic dysfunction and type 2 diabetes. However, the effects of amlexanox on neuroinflammatory responses to amlexanox have not yet been comprehensively studied. In this study, we investigated the novel therapeutic effect of amlexanox on LPS-induced neuroinflammation in vivo, and intraperitoneal injection of amlexanox markedly reduced LPS-induced IKKε levels, proinflammatory cytokines, and microglial activation, as evidenced by ionized calcium-binding adapter molecule 1 (Iba1) immunostaining. Furthermore, amlexanox significantly reduced proinflammatory cytokines and chemokines in LPS-induced bone marrow-derived macrophages (BMDM), murine BV2, and human HMC3 microglial cells. This data provided considerable evidence that amlexanox can be used as a preventive and curative therapy for neuroinflammatory and neurodegenerative diseases. In terms of mechanism aspects, our results demonstrated that the anti-inflammatory action of amlexanox in BV2 microglial cells was through the downregulation of NF-κB and STAT3 signaling pathways. In addition, the combination of amlexanox and SPI (a STAT3 selective inhibitor) showed high efficiency in inhibiting the production of neurotoxic and pro-inflammatory mediators. Overall, our data provide rational insights into the mechanisms of amlexanox as a potential therapeutic strategy for neuroinflammation-related diseases.

Microglia-derived exosomes modulate myelin regeneration via miR-615-5p/MYRF axis

Demyelination and failure of remyelination in the central nervous system (CNS) characterize a number of neurological disorders. Spontaneous remyelination in demyelinating diseases is limited, as oligodendrocyte precursor cells (OPCs), which are often present in demyelinated lesions in abundance, mostly fail to differentiate into oligodendrocytes, the myelinating cells in the CNS. In addition to OPCs, the lesions are assembled numbers of activated resident microglia/infiltrated macrophages; however, the mechanisms and potential role of interactions between the microglia/macrophages and OPCs are poorly understood. Here, we generated a transcriptional profile of exosomes from activated microglia, and found that miR-615-5p was elevated. miR-615-5p bound to 3'UTR of myelin regulator factor (MYRF), a crucial myelination transcription factor expressed in oligodendrocyte lineage cells. Mechanistically, exosomes from activated microglia transferred miR-615-5p to OPCs, which directly bound to MYRF and inhibited OPC maturation. Furthermore, an effect of AAV expressing miR-615-5p sponge in microglia was tested in experimental autoimmune encephalomyelitis (EAE) and cuprizone (CPZ)-induced demyelination model, the classical mouse models of multiple sclerosis. miR-615-5p sponge effectively alleviated disease progression and promoted remyelination. This study identifies miR-615-5p/MYRF as a new target for the therapy of demyelinating diseases.

Nose to brain delivery of Astragaloside IV by β-Asarone modified chitosan nanoparticles for multiple sclerosis therapy

Multiple sclerosis (MS), an autoimmune disease, has been considered an inflammatory disorder of the central nervous system (CNS) with demyelination and axonal damage. Although there are certain first-line therapies to treat MS, their unsatisfactory efficacy is partly due to the limited CNS access after systemic administration. Besides, there is an urgent need to treat MS by enhancing remyelination or neuroprotection, or dampen the activity of microglia. Astragaloside IV (ASI) bears anti-inflammatory, antioxidant, remyelination and neuroprotective activity. While its poor permeability, relatively high molecular weight and low lipophilicity restrict it to reach the brain. Therefore, β-asarone modified ASI loaded chitosan nanoparticles (ASI-βCS-NP) were prepared to enhance the nose-to-brain delivery and therapeutic effects of ASI on EAE mice. The prepared ASI-βCS-NP showed mean size of about 120 nm, and zeta potential from +19 to +25 mV. DiR-βCS-NP was confirmed with good nose-to-brain targeting ability. After intranasal administration, the ASI-βCS-NP significantly reduced behavioral scores, decreased weight loss, suppressed inflammatory infiltration and astrocyte/microglial activation, reduced demyelination and increased remyelination on a mice EAE model. Our findings indicate that ASI-βCS-NP may be a potent treatment for MS after nose-to-brain drug delivery.

Adipocyte-Secreted IL-6 Sensitizes Macrophages to IL-4 Signaling

Complex bidirectional cross talk between adipocytes and adipose tissue immune cells plays an important role in regulating adipose function, inflammation, and insulin responsiveness. Adipocytes secrete the pleiotropic cytokine IL-6 in response to both inflammatory and catabolic stimuli. Previous studies have suggested that IL-6 secretion from adipocytes in obesity may promote adipose tissue inflammation. Here, we investigated catabolic stimulation of adipocyte IL-6 secretion and its impact on adipose tissue immune cells. In obesity, catecholamine resistance reduces cAMP-driven adipocyte IL-6 secretion in response to catabolic signals. By restoring adipocyte catecholamine sensitivity in obese adipocytes, amlexanox stimulates adipocyte-specific IL-6 secretion. We report that in this context, adipocyte-secreted IL-6 activates local macrophage STAT3 to promote Il4ra expression, thereby sensitizing them to IL-4 signaling and promoting an anti-inflammatory gene expression pattern. Supporting a paracrine adipocyte to macrophage mechanism, these effects could be recapitulated using adipocyte conditioned media to pretreat bone marrow-derived macrophages prior to polarization with IL-4. The effects of IL-6 signaling in adipose tissue are complex and context specific. These results suggest that cAMP-driven IL-6 secretion from adipocytes sensitizes adipose tissue macrophages to IL-4 signaling.

Contribution of IL-38 in Lung Immunity during Pseudomonas Aeruginosa-induced Pneumonia

OBJECTIVE

Interleukin-38 (IL-38), a new type of cytokine, is involved in processes such as tissue repair, inflammatory response, and immune response. However, its function in pneumonia caused by Pseudomonas aeruginosa (P. aeruginosa) is still unclear.

METHODS

In this study, we detected circulating IL-38 and cytokines such as IL-1β, IL-6, IL-17A, TNF-α, IL-8, and IL-10 in adults affected by early stage pneumonia caused by P. aeruginosa. Collected clinical data of these patients, such as the APACHE II score, levels of PCT, and oxygenation index when they entering the ICU. Using P. aeruginosa-induced pneumonia WT murine model to evaluate the effect of IL-38 on Treg differentiation, cell apoptosis, survival, tissue damage, inflammation, and bacterial removal.

RESULTS

In clinical research, although IL-38 is significantly increased during the early stages of clinical P. aeruginosa pneumonia, the concentration of IL-38 in the serum of patients who died with P. aeruginosa pneumonia was relatively lower than that of surviving patients. It reveals IL-38 may insufficiently secreted in patients who died with P. aeruginosa pneumonia. Besides, the serum IL-38 level of patients with P. aeruginosa pneumonia on the day of admission to the ICU showed significantly positive correlations with IL-10 and the PaO2/FiO2 ratio but negative correlations with IL-1β, IL-6, IL-8, IL-17, TNF-α, APACHE II score, and PCT In summary, IL-38 might be a molecule for adjuvant therapy in P. aeruginosa pneumonia. In experimental animal models, first recombinant IL-38 improved survival, whereas anti-IL-38 antibody reduced survival in the experimental pneumonia murine model. Secondly, IL-38 exposure reduced the inflammatory response, as suggested by the lung injury, and reduced cytokine levels (IL-1β, IL-6, IL- 17A, TNF-α, and IL-8, but not IL-10). It also increased bacterial clearance and reduced cell apoptosis in the lungs. Furthermore, IL-38 was shown to reduce TBK1 expression in vitro when naive CD4+ T lymphocytes were differentiated to Tregs and played a protective role in P. aeruginosa pneumonia.

CONCLUSIONS

To summarize, the above findings provide additional insights into the mechanism of IL-38 in the treatment of P. aeruginosa pneumonia.

Regulatory T cells: Their role in triple-negative breast cancer progression and metastasis

Triple-negative breast cancer (TNBC) is an aggressive and immunogenic subtype of breast cancer. This tumorigenicity is independent of hormonal or HER2 pathways because of a lack of respective receptor expression. TNBC is extremely prone to drug resistance and early recurrence because of T-regulatory cell (Treg) infiltration into the tumor microenvironment (TME) in addition to other mechanisms like genomic instability. Tumor-infiltrating Tregs interact with both tumor and stromal cells as well as extracellular matrix components in the TME and induce an immune-suppressive phenotype. Hence, treatment of TNBC with conventional therapies remains challenging. Understanding the protective mechanism of Tregs in shielding TNBC from antitumor immune responses in the TME will pave the way for developing novel, immune-based therapeutics. The current review focuses on the role of tumor-infiltrating Tregs in tumor progression and metabolic reprogramming of the TME. The authors have extended their focus to oncotargeting Treg-mediated immune suppression in breast cancer. Because of its potential role in the TME, modulating Treg activity may provide a novel strategic intervention to combat TNBC. Both under laboratory conditions and in clinical trials, currently available anticancer drugs and natural therapeutics as potential agents for targeting Tregs are explored.

The potential value of amlexanox in the treatment of cancer: Molecular targets and therapeutic perspectives

Amlexanox (AMX) is an azoxanthone drug used for decades for the treatment of mouth aphthous ulcers and now considered for the treatment of diabetes and obesity. The drug is usually viewed as a dual inhibitor of the non-canonical IκB kinases IKK-ɛ (inhibitor-kappaB kinase epsilon) and TBK1 (TANK-binding kinase 1). But a detailed target profile analysis indicated that AMX binds directly to twelve protein targets, including different enzymes (IKK-ɛ, TBK1, GRK1, GRK5, PDE4B, 5- and 12-lipoxygenases) and non-enzyme proteins (FGF-1, HSP90, S100A4, S100A12, S100A13). AMX has been demonstrated to have marked anticancer effects in multiple models of xenografted tumors in mice, including breast, colon, lung and gastric cancers and in onco-hematological models. The anticancer potency is generally modest but largely enhanced upon combination with cytotoxic (temozolide, docetaxel), targeted (selumetinib) or biotherapeutic agents (anti-PD-1 and anti-CTLA4 antibodies). The multiple targets participate in the anticancer effects, chiefly IKK-ɛ/TBK1 but also S100A proteins and PDE4B. The review presents the molecular basis of the antitumor effects of AMX. The capacity of the drug to block nonsense-mediated mRNA decay (NMD) is also discussed, as well as AMX-induced reduction of cancer-related pain. Altogether, the analysis provides a survey of the anticancer action of AMX, with the implicated protein targets. The use of this well-tolerated drug to treat cancer should be further considered and the design of newer analogues encouraged.

Isoproterenol-Induced Cardiomyopathy Recovery Intervention: Amlexanox and Forskolin Enhances the Resolution of Catecholamine Stress-Induced Maladaptive Myocardial Remodeling

The increasing incidence of stress-induced cardiomyopathy is due to the complexities of our modern-day lives, which constantly elicit stress responses. Herein, we aimed to explore the therapeutic potential of Amlexanox and Forskolin in promoting the recovery from stress-induced cardiomyopathy. Isoproterenol-induced cardiomyopathy (ICM) models were made, and the following treatment interventions were administered: 5% v/v DMSO as a placebo, Amlexanox (2.5 mg/100 g/day) treatment, Forskolin (0.5 mg/100 g/day), and Amlexanox and Forskolin combination, at their respective aforementioned dosages. The effects of Amlexanox and Forskolin treatment on ICM models were assessed by eletrocardiography and echocardiography. Also, using histological analysis and ELISA, their impact on myocardial architecture and inflammation were ascertained. ICM mice had excessive myocardial fibrosis, hypertrophy, and aggravated LVSDs which were accompanied by massive CD86+ inflammatory cells infiltration. Amlexanox treatment attenuated the myocardial hypertrophy, fibrosis, and inflammation and also slightly improved systolic functions. Meanwhile, forskolin treatment resulted in arrhythmias but significantly enhanced the resolution of myocardial fibrosis and inflammation. Intriguingly, Amlexanox and Forskolin combination demonstrated the most potency at promoting the recovery of the ICM from LVSD by attenuating maladaptive myocardial hypertrophy, fibrosis, and inflammatory responses. Our findings highlight the Amlexanox and Forskolin combination as a potential therapeutic intervention for enhancing cardiac function recovery from stress-induced cardiomyopathy by promoting the resolution of maladaptive cardiac remodeling.

Drug Repurposing for Glioblastoma and Current Advances in Drug Delivery-A Comprehensive Review of the Literature

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with an extremely poor prognosis. There is a dire need to develop effective therapeutics to overcome the intrinsic and acquired resistance of GBM to current therapies. The process of developing novel anti-neoplastic drugs from bench to bedside can incur significant time and cost implications. Drug repurposing may help overcome that obstacle. A wide range of drugs that are already approved for clinical use for the treatment of other diseases have been found to target GBM-associated signaling pathways and are being repurposed for the treatment of GBM. While many of these drugs are undergoing pre-clinical testing, others are in the clinical trial phase. Since GBM stem cells (GSCs) have been found to be a main source of tumor recurrence after surgery, recent studies have also investigated whether repurposed drugs that target these pathways can be used to counteract tumor recurrence. While several repurposed drugs have shown significant efficacy against GBM cell lines, the blood–brain barrier (BBB) can limit the ability of many of these drugs to reach intratumoral therapeutic concentrations. Localized intracranial delivery may help to achieve therapeutic drug concentration at the site of tumor resection while simultaneously minimizing toxicity and side effects. These strategies can be considered while repurposing drugs for GBM.

Identification of key genes and microRNAs for multiple sclerosis using bioinformatics analysis

To better understand the molecular mechanism underlying the pathogenesis of multiple sclerosis (MS), we aimed to identify the key genes and microRNAs (miRNA) associated with MS and analyze their interactions. Differentially expressed genes (DEGs) and miRNAs (DEMs) based on the gene miRNA dataset GSE17846 and mRNA dataset GSE21942 were determined using R software. Next, we performed functional enrichment analysis and constructed a protein-protein interaction network. Data validation was performed to ensure the reliability of hub genes. The miRNA-mRNA regulatory network was constructed. In total, 47 DEMs and 843 DEGs were identified. Protein-protein interaction network analysis identified several hub genes, including JUN, FPR2, AKT1, POLR2L, LYZ, CXCL8, HBB, CST3, CTSZ, and MMP9, especially LYZ and CXCL8. We constructed an miRNA-mRNA regulatory network and found that hsa-miR-142-3p, hsa-miR-107, hsa-miR-140-5p, and hsa-miR-613 were the most important miRNAs. This study reveals some key genes and miRNAs that may be involved in the pathogenesis of MS, providing potential targets for the diagnosis and treatment of MS.

Amlexanox and Forskolin Prevents Isoproterenol-Induced Cardiomyopathy by Subduing Cardiomyocyte Hypertrophy and Maladaptive Inflammatory Responses

Chronic catecholamine stress (CCS) induces the occurrence of cardiomyopathy-pathological cardiac hypertrophy (PCH), which is characterized by left ventricular systolic dysfunction (LVSD). Recently, mounting evidence has implicated myocardial inflammation in the exacerbation of pathological cardiac remodeling. However, there are currently no well-defined treatment interventions or regimes targeted at both the attenuation of maladaptive myocardial hypertrophy and inflammation during CCS to prevent PCH. G protein-coupled receptor kinase 5 (GRK5) and adenylyl cyclases (ACs)-cAMP mediates both cardiac and inflammatory responses. Also, GRK5 and ACs are implicated in stress-induced LVSD. Herein, we aimed at preventing PCH during CCS via modulating adaptive cardiac and inflammatory responses by inhibiting GRK5 and/or stimulating ACs. Isoproterenol-induced cardiomyopathy (ICM) was modeled using 0.5 mg/100 g/day isoproterenol injections for 40 days. Alterations in cardiac and inflammatory responses were assessed from the myocardia. Similarities in the immunogenicity of cardiac troponin I (cTnI) and lipopolysaccharide under CCS were assessed, and Amlexanox (35 μM/ml) and/or Forskolin (10 μM/ml) were then employed in vitro to modulate adaptive inflammatory responses by inhibiting GRK5 or activating ACs-cAMP, respectively. Subsequently, Amlexanox (2.5 mg/100 g/day) and/or Forskolin (0.5 mg/100 g/day) were then translated into in vivo during CCS to modulate adaptive cardiac and inflammatory responses. The effects of Amlexanox and Forskolin on regulating myocardial systolic functions and inflammatory responses during CCS were ascertained afterward. PCH mice had excessive myocardial hypertrophy, fibrosis, and aggravated LVSD, which were accompanied by massive CD68⁺ inflammatory cell infiltrations. In vitro, Forskolin-AC/cAMP was effective than Amlexanox-GRK5 at downregulating proinflammatory responses during stress; nonetheless, Amlexanox and Forskolin combination demonstrated the most efficacy in modulating adaptive inflammatory responses. Individually, the translated Amlexanox and Forskolin treatment interventions were ineffective at subduing the pathological remodeling and sustaining cardiac function during CCS. However, their combination was potent at preventing LVSD during CCS by attenuating maladaptive myocardial hypertrophy, fibrosis, and inflammatory responses. The treatment intervention attained its potency mainly via Forskolin-ACs/cAMP-mediated modulation of cardiac and inflammatory responses, coupled with Amlexanox inhibition of GRK5 mediated maladaptive cascades. Taken together, our findings highlight the Amlexanox and Forskolin combination as a potential therapeutic intervention for preventing the occurrence of pathological cardiac hypertrophy during chronic stress.

Arachidonic Acid 15-Lipoxygenase: Effects of Its Expression, Metabolites, and Genetic and Epigenetic Variations on Airway Inflammation

Arachidonic acid 15-lipoxygenase (ALOX15) is an enzyme that can oxidize polyunsaturated fatty acids. ALOX15 is strongly expressed in airway epithelial cells, where it catalyzes the conversion of arachidonic acid to 15-hydroxyeicosatetraenoic acid (15-HETE) involved in various airway inflammatory diseases. Interleukin (IL)-4 and IL-13 induce ALOX15 expression by activating Jak2 and Tyk2 kinases as well as signal transducers and activators of transcription (STATs) 1/3/5/6. ALOX15 up-regulation and subsequent association with phosphatidylethanolamine-binding protein 1 (PEBP1) activate the mitogen-activated extracellular signal-regulated kinase (MEK)-extracellular signal-regulated kinase (ERK) pathway, thus inducing eosinophil-mediated airway inflammation. In addition, ALOX15 plays a significant role in promoting the migration of immune cells, such as immature dendritic cells, activated T cells, and mast cells, and airway remodeling, including goblet cell differentiation. Genome-wide association studies have revealed multiple ALOX15 variants and their significant correlation with the risk of developing airway diseases. The epigenetic modifications of the ALOX15 gene, such as DNA methylation and histone modifications, have been shown to closely relate with airway inflammation. This review summarizes the role of ALOX15 in different phenotypes of asthma, chronic obstructive pulmonary disease, chronic rhinosinusitis, aspirin-exacerbated respiratory disease, and nasal polyps, suggesting new treatment strategies for these airway inflammatory diseases with complex etiology and poor treatment response.

Immunomodulatory Role and Therapeutic Potential of Non-Coding RNAs Mediated by Dendritic Cells in Autoimmune and Immune Tolerance-Related Diseases

Dendritic cells (DCs) are professional antigen-presenting cells that act as a bridge between innate immunity and adaptive immunity. After activation, DCs differentiate into subtypes with different functions, at which point they upregulate co-stimulatory molecules and produce various cytokines and chemokines. Activated DCs also process antigens for presentation to T cells and regulate the differentiation and function of T cells to modulate the immune state of the body. Non-coding RNAs, RNA transcripts that are unable to encode proteins, not only participate in the pathological mechanisms of autoimmune-related diseases but also regulate the function of immune cells in these diseases. Accumulating evidence suggests that dysregulation of non-coding RNAs contributes to DC differentiation, functions, and so on, consequently producing effects in various autoimmune diseases. In this review, we summarize the main non-coding RNAs (miRNAs, lncRNAs, circRNAs) that regulate DCs in pathological mechanisms and have tremendous potential to give rise to novel therapeutic targets and strategies for multiple autoimmune diseases and immune tolerance-related diseases.

Activation of macrophage TBK1-HIF-1α-mediated IL-17/IL-10 signaling by hyperglycemia aggravates the complexity of coronary atherosclerosis: An in vivo and in vitro study

Our purpose was to study the effect of hyperglycemia on macrophage TBK1-HIF-1α-mediated IL-17/IL-10 signaling and its correlation with coronary atherosclerosis. A total of 135 patients with coronary heart disease (CHD) were divided into a stable CHD (SCHD) group (n = 30) and an acute myocardial infarction (AMI) group (n = 105) [nondiabetes mellitus (non-DM)-AMI, n = 60; DM-AMI, n = 45] from January to September 2020. The SYNTAX score and metabolic and inflammatory markers were quantified and compared. THP-1 cell studies and an animal study of coronary intimal hyperplasia were also carried out. We found that the DM-AMI group showed a higher SYNTAX score than the non-DM-AMI group (P < .05). The DM-AMI group showed the highest expression levels of TANK-binding kinase 1 (TBK1), hypoxia-inducible factor 1α (HIF-1α), and interleukin (IL)-17 and the lowest expression level of IL-10, followed by the non-DM-AMI group and the SCHD group (P < .05). THP-1 cell studies showed that BAY87-2243 (a HIF-1α inhibitor) reversed the increase in IL-17 and decrease in IL-10 expression induced by hyperglycemia. Amlexanox (a TBK1 inhibitor) reversed the increase in HIF-1α expression induced by hyperglycemia. Amlexanox treatment resulted in lower coronary artery intimal hyperplasia and a larger lumen area in a diabetic swine model. We conclude that hyperglycemia might aggravate the complexity of coronary atherosclerosis through activation of TBK1-HIF-1α-mediated IL-17/IL-10 signaling. Thus, TBK1 may be a novel drug therapy target for CHD complicated with DM.

Acute TBK1/IKK-ε Inhibition Enhances the Generation of Disease-Associated Microglia-Like Phenotype Upon Cortical Stab-Wound Injury

Traumatic brain injury has a poorer prognosis in elderly patients, possibly because of the enhanced inflammatory response characteristic of advanced age, known as “inflammaging.” Recently, reduced activation of the TANK-Binding-Kinase 1 (Tbk1) pathway has been linked to age-associated neurodegeneration and neuroinflammation. Here we investigated how the blockade of Tbk1 and of the closely related IKK-ε by the small molecule Amlexanox could modify the microglial and immune response to cortical stab-wound injury in mice. We demonstrated that Tbk1/IKK-ε inhibition resulted in a massive expansion of microglial cells characterized by the TMEM119⁺/CD11c⁺ phenotype, expressing high levels of CD68 and CD317, and with the upregulation of Cst7a, Prgn and Ccl4 and the decrease in the expression levels of Tmem119 itself and P2yr12, thus a profile close to Disease-Associated Microglia (DAM, a subset of reactive microglia abundant in Alzheimer’s Disease and other neurodegenerative conditions). Furthermore, Tbk1/IKK-ε inhibition increased the infiltration of CD3⁺ lymphocytes, CD169⁺ macrophages and CD11c⁺/CD169⁺ cells. The enhanced immune response was associated with increased expression of Il-33, Ifn-g, Il-17, and Il-19. This upsurge in the response to the stab wound was associated with the expanded astroglial scars and increased deposition of chondroitin-sulfate proteoglycans at 7 days post injury. Thus, Tbk1/IKK-ε blockade results in a massive expansion of microglial cells with a phenotype resembling DAM and with the substantial enhancement of neuroinflammatory responses. In this context, the induction of DAM is associated with a detrimental outcome such as larger injury-related glial scars. Thus, the Tbk1/IKK-ε pathway is critical to repress neuroinflammation upon stab-wound injury and Tbk1/IKK-ε inhibitors may provide an innovative approach to investigate the consequences of DAM induction.

Ponesimod modulates the Th1/Th17/Treg cell balance and ameliorates disease in experimental autoimmune encephalomyelitis

Sphingosine-1-phosphate receptor 1 (S1P1) plays an important role in autoimmune disease. Here, we evaluated whether ponesimod, an S1P1 modulator, affects inflammation in experimental autoimmune encephalomyelitis (EAE) and investigated Th1/Th2/Th17/Treg cell subsets. Ponesimod treatment ameliorated EAE and alleviated inflammatory infiltration. Compared with untreated EAE, ponesimod-treated mice had lower Th1 and Th17 cell numbers and higher Treg cell numbers; their IFN-γ, T-bet, IL-17, and RORγt levels as well as their pmTOR/mTOR ratio were diminished, while their TGF-β and Foxp3 levels were enhanced. These results suggest that ponesimod modulates the Th1/Th17/Treg balance and regulates the mTOR pathway.

9,10-Anhydrodehydroartemisinin Attenuates Experimental Autoimmune Encephalomyelitis by Inhibiting Th1 and Th17 Cell Differentiation

Human inflammatory disease, multiple sclerosis (MS), is a demyelinating disease of central nervous system (CNS). The experimental autoimmune encephalomyelitis (EAE) is the most commonly used as experimental model because of its key pathological features' approximation of MS. The interaction between complex elements in immune system and in the CNS determines the MS pathogenesis. However, there is no cure for MS and the treatment for MS still encounters great challenges. Thus, finding a more effective disease-modifying treatment is imminent. In the present study, we investigated whether 9,10-Anhydrodehydroartemisin (ADART), a compound derived from artemisinin, could decrease demyelination in EAE and the underlying mechanisms. In established EAE mice, 100 mg/kg 9,10-Anhydrodehydroartemisinin (ADART) effectively reduced CNS and peripheral immune system infiltration inflammatory cells including CD4⁺ IFN-γ⁺ Th1 cells and CD4⁺ IL-17A⁺ Th17 cells. Correspondingly, the serum level of IFN-γ and IL-17A was also reduced. In vitro, ADART almost completely inhibited Th17 differentiation, and partially inhibited Th1 differentiation in 10 μM. This research revealed that ADART could be a great promising avenue among current therapies for MS.

Amlexanox: A Novel Therapeutic for Atopic, Metabolic, and Inflammatory Disease

Amlexanox, a small molecule targeted therapy which has been used in the treatment of atopic conditions was previously but is not currently available in the United States. Amlexanox has also been legally utilized and administered in Japan as a treatment for asthma, a chronic pulmonary disease characterized by inflammation of the lower respiratory tract. Amlexanox's immune modulatory effects have been the subject of studies which have repurposed the drug for potential therapeutic applications in metabolic and inflammatory disease. Because amlexanox inhibits TANK-binding kinase1 (TBK1) and nuclear factor kB kinase epsilon (IKKε), several studies have demonstrated its usefulness through its evidence downregulation of the immune system and attenuation of downstream TBK1 signaling. Novel therapies, such as amlexanox, for inflammatory conditions such as asthma will continue to be of value in clinical management. This report summarizes key applications of the drug based on animal and human studies and explores its potential in treatment of metabolic and inflammatory diseases.

The combined treatment of NAD+ and atorvastatin ameliorates the development of experimental autoimmune encephalomyelitis in C57BL/6 mice

Multiple sclerosis (MS) is a demyelinating and degenerating disorder of the central nervous system impacting many patients worldwide. Due to the complex pathogenesis of MS, drugs to treat MS often show partial effectiveness. Earlier experiments have demonstrated that both atorvastatin and nicotinamide adenine dinucleotide (NAD+) may ameliorate experimental autoimmune encephalomyelitis (EAE), which is known as a classical model of MS, via different protective mechanisms. Since combination therapy can exhibit more beneficial effects than monotherapy, we observed the protective effects of combined treatment of atorvastatin and NAD+ in EAE mice. Our results showed that the combined treatment of these two drugs at half of their optimal dosages had synergistic effect to alleviate the severity of EAE in mice than treatment with each alone. The combined treatment of EAE mice with atorvastatin plus NAD+ relieved the clinical signs and histologic changes, increased the proportion of Treg cells, attenuated IL-17 production, reduced proinflammatory cytokine secretion of Th17 cells, and increased cytokine secretion of Treg cells. In addition, the combined treatment also diminished phosphorylation of both P38 MAPK and ERK, while elevated SIRT1 expression. Taken together, these data suggested that combined treatment with NAD+ and atorvastatin could attenuate the progression of EAE by synergistic immune regulation.

Calcitriol inhibits osteoclastogenesis in an inflammatory environment by changing the proportion and function of T helper cell subsets (Th2/Th17)

Objectives

Previously, we found that by regulating T helper (Th) cell polarization, calcitriol intervention inhibited lipopolysaccharide (LPS)‐induced alveolar bone loss in an animal periodontitis model, but the underlying cellular events remain unknown.

Materials and methods

In this study, mouse Th cells were incubated in an inflammatory environment in the presence of dendritic cells (DCs) and LPS. Then, the potential of the Th cells to undergo Th2/Th17 polarization, the RANKL expression of the polarized Th cells and the subsequent influences of the polarized Th cells on RAW264.7 cell osteoclastogenesis in response to calcitriol administration were assessed. Finally, the effects of calcitriol on antigen presentation by DCs during these cellular events were evaluated.

Results

In response to calcitriol administration, Th cells in an inflammatory environment exhibited an enhanced potential for Th2 polarization along with a decreased potential for Th17 polarization. In addition, RANKL expression in Th17‐polarized cells was largely inhibited. Furthermore, inflammation‐induced osteoclastogenesis in RAW264.7 cells was suppressed following coculture with calcitriol‐treated Th cells. During these cellular events, increased expression of Th2 promoters (such as OX‐40L and CCL17) and decreased expression of Th17 promoters (such as IL‐23 and IL‐6) were found in DCs.

Conclusions

Calcitriol can inhibit osteoclastogenesis in an inflammatory environment by changing the proportion and function of Th cell subsets. Our findings suggest that calcitriol may be an effective therapeutic agent for treating periodontitis.

Nicotine attenuates concanavalin A-induced liver injury in mice by regulating the α7-nicotinic acetylcholine receptor in Kupffer cells

Nicotine, a potent parasympathomimetic alkaloid, manifests anti-inflammatory properties by activating nicotinic acetylcholine receptors (nAChRs). In this study, we evaluated the effects of nicotine on concanavalin A (ConA)-induced autoimmune hepatitis. Nicotine (0.5 and 1 mg/kg) was intraperitoneally administered to BALB/c mice and mice were intravenously injected with ConA (15 mg/kg) to induce hepatitis. The results showed that nicotine treatment ameliorated pathological lesions in livers and significantly suppressed the expression of pro-inflammatory cytokines in the livers. Such effects were mediated by inhibiting the nuclear factor-kappa B (NF-κB) signaling in livers. Interestingly, nicotine inhibited the ConA-induced inflammatory response in primary cultured Kupffer cells (KCs) but did not alter the proliferation of splenocytes. The protective effects of nicotine against ConA-induced hepatitis were abolished in KC-depleted mice, indicating the requirement of KCs in this process. Additionally, the expression of α7-nAChR on KCs was dramatically increased by nicotine treatment, and the protective effects of nicotine on ConA-induced liver injury were significantly suppressed by treatment with methyllycaconitine (MLA), a specific α7-nAChR antagonist. Consistently, in primary cultured KCs, the activation of NF-κB signaling was also regulated by nicotine treatment. This study suggests that nicotine increases α7-nAChR-mediated cholinergic activity in KCs resulting in decrease of ConA-induced autoimmune hepatitis through inhibiting NF-κB signaling.

MicroRNA-223-3p modulates dendritic cell function and ameliorates experimental autoimmune myocarditis by targeting the NLRP3 inflammasome

Autoimmune myocarditis is a cause of dilated cardiomyopathy and heart failure. MicroRNAs regulate many immune processes, but their role in aberrant inflammation during autoimmune myocarditis remains unclear. In this study, we investigated the role of miR-223-3p in experimental autoimmune myocarditis (EAM). We found that miR-223-3p expression was significantly lower in EAM mice than that in normal mice. miR-223-3p inhibited NLRP3 inflammasome expression, promoting the polarization of dendritic cells (DCs) towards a tolerogenic DC phenotype. miR-223-3p effectively induced regulatory T cell (Treg) generation by inhibiting the function of antigen-presenting DCs. Transfer of miR-223-3p-overexpressing DCs protected mice against the development of EAM. Our findings suggest that miR-223-3p is involved in the induction of the tolerogenic DC phenotype and regulates tolerance in autoimmune myocarditis.