The prostaglandin E2 increases the production of IL-17 and the expression of costimulatory molecules on γδ T cells in rheumatoid arthritis

High-throughput metabolomics exploring the pharmacological effects and mechanism of icariin on rheumatoid arthritis rat based on ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Introduction

Metabolomics could provide insights into the pharmacological effects and action mechanisms of drugs through assessment of the changes in relevant biomarkers and biological pathways. Icariin (ICA) is a promising ffavonoid compound known to have significant anticancer activity; however, the pharmacological mechanisms of ICA in the treatment of rheumatoid arthritis (RA) need to be explored further.

Methods

The changes in the metabolic profiles of serum samples were revealed using non-targeted metabolomics based on ultrahigh-performance liquid chromatography coupled with quadrupole time-of-fight mass spectrometry. Tissue histopathology, physical parameters, and biochemical indicators were also measured and analyzed to reveal the mechanisms of ICA in the treatment of RA.

Results and discussion

Thirty-one potential biomarkers were identified to highlight the metabolic disorders in an RA animal model, out of which twenty-three were regulated by ICA treatment. These biomarkers were mainly involved in alanine, aspartate, and glutamate metabolism; arachidonic acid metabolism; citrate cycle; pyruvate metabolism; and glycolysis/gluconeogenesis pathways. The anticancer mechanism of ICA on RA may be attributed to amelioration of the amino acid metabolism, unsaturated fatty acid metabolism, citrate cycle, pyruvate metabolism, and others, which in turn regulate the oxidative stress state and inflammatory effects. Thus, metabolomics is a promising approach for revealing the biomarker distribution and pathways of RA to determine the effects and mechanisms of ICA, which can benefit the development of natural medicines.

The recent progress of γδ T cells and its targeted therapies in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune condition that mostly impacts the joints. During the advanced phases of the disorder, it may be accompanied by other problems. While the precise cause of RA is uncertain, various research has been conducted to gain a better understanding of the immunological processes involved in the development of RA. T cells are acknowledged as significant contributors to the progression of RA because of their roles in cytokine secretion, antigen presentation, and facilitating B cells in the manufacture of antibodies. γδ T cells are a small subset of T cells that have significant functions in the context of infection and diseases linked with tumors. γδ T cells have been the subject of investigation in autoimmune disorders in recent years. This review focused on the involvement of γδ T lymphocytes in the development of RA. In this article, we provide an analysis of the immunological capabilities of γδ T cells, intending to comprehend their significance in RA, which could be pivotal in the creation of innovative clinical treatments.

Network pharmacology and experimental validation methods to reveal the active compounds and hub targets of Curculigo orchioides Gaertn in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease that can lead to joint destruction and deformity. Curculigo orchioides Gaertn (CO) was previously revealed to play a significant role in RA treatment. However, the main active ingredients and molecular mechanisms of CO in regulating RA are still unclear.

METHODS

The active ingredients of CO were obtained from the Traditional Chinese Medicine Systems Pharmacology database and published literature. The targets corresponding to these compounds and the targets linked to RA were collected from public databases. The "ingredient-target" and "protein-protein interaction" networks were constructed to screen the main active ingredients and hub targets of CO in the treatment of RA. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment assays were used to elucidate the potential pharmacological mechanism of CO in RA. Molecular docking was performed to detect the binding between the main active ingredients and hub targets. Collagen-induced arthritis rats were used to validate the hub targets of CO against RA.

RESULTS

Network pharmacological topology analysis showed that caffeine, 2,4-dichloro-5-methoxy-3-methylphenol, curculigoside, orcinol glucoside, and orcin were the main active ingredients of CO, and matrix metalloproteinase 9 (MMP9), transcription factor AP-1 (JUN), prostaglandin-endoperoxide synthase 2 (PTGS2), brain-derived neurotrophic factor, and receptor-type tyrosine-protein phosphatase C were the hub targets of CO for RA treatment. Molecular docking revealed that curculigoside and orcinol glucoside had effective binding potential with MMP9, JUN, and PTGS2, respectively. In vivo experiments demonstrated that CO alleviated RA symptoms and inhibited the expression of MMP9, JUN, and PTGS2 proteins.

CONCLUSIONS

Our study demonstrates the main active ingredients and potential targets of CO against RA, laying an experimental foundation for the development and application of CO as an anti-RA drug.

Lipid metabolism and rheumatoid arthritis

As a chronic progressive autoimmune disease, rheumatoid arthritis (RA) is characterized by mainly damaging the synovium of peripheral joints and causing joint destruction and early disability. RA is also associated with a high incidence rate and mortality of cardiovascular disease. Recently, the relationship between lipid metabolism and RA has gradually attracted attention. Plasma lipid changes in RA patients are often detected in clinical tests, the systemic inflammatory status and drug treatment of RA patients can interact with the metabolic level of the body. With the development of lipid metabolomics, the changes of lipid small molecules and potential metabolic pathways have been gradually discovered, which makes the lipid metabolism of RA patients or the systemic changes of lipid metabolism after treatment more and more comprehensive. This article reviews the lipid level of RA patients, as well as the relationship between inflammation, joint destruction, cardiovascular disease, and lipid level. In addition, this review describes the effect of anti-rheumatic drugs or dietary intervention on the lipid profile of RA patients to better understand RA.

Photodynamic Therapy-Induced Cyclooxygenase 2 Expression in Tumor-Draining Lymph Nodes Regulates B-Cell Expression of Interleukin 17 and Neutrophil Infiltration

Photodynamic therapy (PDT) is an effective anticancer modality approved by the U.S. Food and Drug Administration (FDA). Antitumor immunity can be augmented during PDT by inducing sterile inflammation in an acute manner, and this process is characterized by interleukin 17 (IL-17)-mediated neutrophil infiltration to tumor-draining lymph nodes (TDLNs). However, the inflammatory factors that influence IL-17 expression in TDLNs are poorly understood. Prior studies have linked the cyclooxygenase 2 (COX2)-driven prostaglandin E₂ (PGE2) pathway to IL-17 expression. Here, we report that an immune-activating PDT regimen (imPDT) induces COX2/PGE2 expression in TDLNs, whereby IL-17 expression is facilitated without corresponding effects on the expression of RORγt, the transcriptional driver of the canonical IL-17 pathway. Pharmacologic inhibition with NS398, a COX2 inhibitor, was utilized to demonstrate that imPDT-induced COX2 regulates RORγt-independent expression of IL-17 by B cells and neutrophil entry into TDLNs. Depletion of B cells prior to imPDT significantly reduced neutrophil entry into TDLNs following treatment, and diminishes the efficacy of imPDT, which is dependent upon antitumor immunity. These findings are suggestive of a novel role for B cells in the augmentation of antitumor immunity by imPDT.

Pro- and anti-inflammatory bioactive lipids imbalance contributes to the pathobiology of autoimmune diseases

Autoimmune diseases are driven by T_H17 cells that secrete pro-inflammatory cytokines, especially IL-17. Under normal physiological conditions, autoreactive T cells are suppressed by TGF-β and IL-10 secreted by microglia and dendritic cells. When this balance is upset due to injury, infection and other causes, leukocyte recruitment and macrophage activation occurs resulting in secretion of pro-inflammatory IL-6, TNF-α, IL-17 and PGE2, LTs (leukotrienes) accompanied by a deficiency of anti-inflammatory LXA4, resolvins, protecting, and maresins. PGE2 facilitates T_H1 cell differentiation and promotes immune-mediated inflammation through T_H17 expansion. There is evidence to suggest that autoimmune diseases can be suppressed by anti-inflammatory bioactive lipids LXA4, resolvins, protecting, and maresins. These results imply that systemic and/or local application of LXA4, resolvins, protecting, and maresins and administration of their precursors AA/EPA/DHA could form a potential therapeutic approach in the prevention and treatment of autoimmune diseases.

Research progress on inflammatory mechanism of primary Sjögren syndrome

Primary Sjögren syndrome is an autoimmune disease, in which a large number of lymphocytes infiltrate the exocrine glands and cause gland dysfunction. Its pathogenesis is related to the chronic inflammation of the exocrine glands caused by genetic factors, immunodeficiency or viral infection. Long-term inflammation leads to accelerated apoptosis of epithelial cells, disordered gland structure, increased expression of proinflammatory cytokine such as CXC subfamily ligand (CXCL) 12, CXCL13, B cell-activating factor (BAF), interleukin (IL)-6, interferon (IFN)-γ and tumor necrosis factor (TNF)-α in submandibular gland. With the action of antigen-presenting cells such as dendritic cells and macrophages, lymphocytes (mainly B cells) are induced to mature in secondary lymphoid organs and migrate to the submandibular gland to promotes the formation of germinal centers and the synthesis of autoantibodies. Meanwhile, innate lymphocytes, vascular endothelial cells and mucosa-associated constant T cells as important immune cells, also participated in the inflammatory response of the submandibular gland in primary Sjögren syndrome through different mechanisms. This process involves the activation of multiple signal pathways such as JAK/STAT, MAPK/ERK, PI3K/AKT/mTOR, PD-1/PD-L1, TLR/MyD88/NF-κB, BAF/BAF-R and IFN. These signaling pathways interact with each other and are intricately complex, causing lymphocytes to continuously activate and invade the submandibular glands. This article reviews the latest literature to clarify the mechanism of submandibular gland inflammation in primary Sjögren syndrome, and to provide insights for further research.

Prostaglandin E2 amplifies IL-17 production by γδ T cells during barrier inflammation

Interleukin-17 (IL-17)-producing γδ (γδ17) T cells are innate-like lymphocytes that contribute to protective anti-microbial responses but are also implicated in pathogenic inflammation at barrier sites. Understanding tissue-specific signals that regulate this subset is important to boost host defense mechanisms, but also to mitigate immunopathology. Here, we demonstrate that prostaglandin E2 (PGE2), a cyclooxygenase-dependent member of the eicosanoid family, directly enhances cytokine production by circulating and tissue-specific γδ17 T cells in vitro. Gain- and loss-of-function in vivo approaches further reveal that although provision of PGE2 amplifies psoriasiform inflammation, ablation of host mPGES1-dependent PGE2 synthesis is dispensable for cutaneous γδ17 T cell activation. By contrast, loss of endogenous PGE2 production or depletion of the gut microbiota compromises intestinal γδ17 T cell responses and increases disease severity during experimental colitis. Together, our results demonstrate how a lipid mediator can synergize with tissue-specific signals to enhance innate lymphocyte production of IL-17 during barrier inflammation.

Prostanoids and Resolution of Inflammation - Beyond the Lipid-Mediator Class Switch

Bioactive lipid mediators play a major role in regulating inflammatory processes. Herein, early pro-inflammatory phases are characterized and regulated by prostanoids and leukotrienes, whereas specialized pro-resolving mediators (SPM), including lipoxins, resolvins, protectins, and maresins, dominate during the resolution phase. While pro-inflammatory properties of prostanoids have been studied extensively, their impact on later phases of the inflammatory process has been attributed mainly to their ability to initiate the lipid-mediator class switch towards SPM. Yet, there is accumulating evidence that prostanoids directly contribute to the resolution of inflammation and return to homeostasis. In this mini review, we summarize the current knowledge of the resolution-regulatory properties of prostanoids and discuss potential implications for anti-inflammatory, prostanoid-targeted therapeutic interventions.