Interleukin-6 (IL-6) Receptor Antagonist Protects Against Rheumatoid Arthritis

Revolutionizing rheumatoid arthritis therapy: harnessing cytomembrane biomimetic nanoparticles for novel treatment strategies

Rheumatoid arthritis (RA) is a systemic immune disease with severe implications for joint health. The issue of non-specific drug distribution potentially limits the therapeutic efficacy and increases the risk associated with RA treatment. Researchers employed cytomembrane-coated biomimetic nanoparticles (NPs) to enhance the targeting delivery efficacy to meet the demand for drug accumulation within the affected joints. Furthermore, distinct cytomembranes offer unique functionalities, such as immune cell activation and augmented NP biocompatibility. In this review, the current strategies of RA treatments were summarized in detail, and then an overview of RA's pathogenesis and the methodologies for producing cytomembrane-coated biomimetic NPs was provided. The application of cytomembrane biomimetic NPs derived from various cell sources in RA therapy is explored, highlighting the distinctive attributes of individual cytomembranes as well as hybrid membrane configurations. Through this comprehensive assessment of cytomembrane biomimetic NPs, we elucidate the prospective applications and challenges in the realm of RA therapy, and the strategy of combined therapy is proposed. In the future, cytomembrane biomimetic NPs have a broad therapeutic prospect for RA.

Circulating interleukin-39 as a potential biomarker for rheumatoid arthritis diagnosis

BACKGROUND

Imbalances in cytokine networks have been shown to be a possible cause of rheumatoid arthritis (RA). The interleukin (IL)-12 family is involved in the pathogenesis of autoimmune diseases including RA, while IL-39 is a newly discovered member of the IL-12 family, although its role in RA remains unclear. The purpose of the present study was to detect the expression of IL-39 in the sera of patients with RA and its relationship with RA activity.

METHODS

We recruited 46 patients with RA and 35 healthy controls at Ningbo Sixth Hospital. Blood samples were collected for biochemical analysis, and disease activity scores of 28 joints based on C-reactive protein were monitored. Serum concentrations of IL-39 were determined using an enzyme-linked immunosorbent assay. The Pearson correlation test was used to analyze the association between serum IL-39 levels and clinical indicators.

RESULTS

Serum levels of IL-39 were significantly higher in patients with RA compared with healthy controls (p < 0.0001). IL-39 levels positively correlated with rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), and IgM; RF positively correlated with ESR. Receiver operating characteristic curve analysis showed that IL-39 has diagnostic value for RA (p < 0.0001).

CONCLUSIONS

The significant increase of IL-39 levels in serum of patients with RA and its positive correlation with clinical indicators suggest that IL-39 may serve as biomarker for the diagnosis of RA.

Th17 Cells: Orchestrators of Mucosal Inflammation and Potential Therapeutic Targets

T helper 17 (Th17) cells represent a specialized subgroup of effector CD4+ T cells known for their role in provoking neutrophil-driven tissue inflammation, particularly within mucosal tissues. Although they are pivotal for defending the host against extracellular bacteria and fungi, they have also been associated with development of various T cell-mediated inflammatory conditions, autoimmune diseases, and even cancer. Notably, Th17 cells exhibit a dual nature, with different Th17 cell subtypes showcasing distinct effector functions and varying capacities to incite autoimmune tissue inflammation. Furthermore, Th17 cells exhibit significant plasticity, which carries important functional implications, both in terms of their expression of cytokines typically associated with other effector T cell subsets and in their interactions with regulatory CD4+ T cells. The intricate balance of Th17 cytokines can also be a double-edged sword in inflammation, autoimmunity, and cancer. Within this article, we delve into the mechanisms that govern the differentiation, function, and adaptability of Th17 cells. We culminate with an exploration of therapeutic potentials in harnessing the power of Th17 cells and their cytokines. Targeted interventions to modulate Th17 responses are emerging as promising strategies for autoimmunity, inflammation, and cancer treatment. By precisely fine-tuning Th17-related pathways, we may unlock new avenues for personalized therapeutic approaches, aiming to restore immune balance, alleviate the challenges of these disorders, and ultimately enhance the quality of life for individuals affected by them.

Expression analysis of cytokines IL-5, IL-6, IL-8, IL-17 and VEGF in breast cancer patients

OBJECTIVE

To investigate the relationship between changes in peripheral blood vascular endothelial growth factor (VEGF), interleukin-5 (IL-5), interleukin-6 (IL-6), interleukin-8 (IL-8) and interleukin-17 (IL-17) concentrations in breast cancer patients and their significance and clinical value in breast cancer staging and invasive metastasis.

METHODS

From September 2021 to April 2022, 60 breast cancer patients from Chongqing Medical University Hospital No. 2022 were enrolled in the breast breast cancer surgery group, while 30 patients with benign breast disease were enrolled in the control group during the same period. Venous blood samples were collected at admission and 1 week after surgery to determine the expression of these factors in serum. Statistical methods such as Wilcoxon test and Spearman correlation analysis were used to analyze the relationship between the above factors and the clinicopathological characteristics of the patients.

RESULTS

By analyzing data from patients with benign and malignant breast tumors, an association was found with serum levels of IL-6, IL-17 and VEGF. Their respective areas under the operating characteristic curve were 0.649, 0.734 and 0.656 (P < 0.05). There were significant differences in the cytokine expression levels of IL-17 and VEGF in different molecular typing (P values were 0.008 and 0.040, respectively). The expression levels of IL-17 and VEGF were higher in HER-2 receptor-positive and triple-negative patients than in hormone receptor-positive patients (P < 0.05). Also, no significant correlation was found between the various cytokines mentioned in the article and breast cancer lymph node metastasis and Tumor Node Metastasis stage (TNM stage). In addition, in the breast cancer surgery group, postoperative VEGF levels were lower (P < 0.05) and IL-6 levels were higher (P < 0.05) compared to preoperative levels.

CONCLUSIONS

Serum IL-6, IL-17, and VEGF are strongly associated with breast cancer development and can be used as a reference indicators for breast cancer diagnosis. In addition, post-operative VEGF levels decreases and IL-6 levels increases compared to pre-operative levels, which can also be used as an a postoperative follow-up indicator. In contrast, IL-5 and IL-8 have not found to be significantly associated with breast cancer patients in this study, which requires further study.

Research progress on Th17 and T regulatory cells and their cytokines in regulating atherosclerosis

Background

Coronary heart disease due to atherosclerosis is the leading cause of death worldwide. Atherosclerosis is considered a chronic inflammatory state in the arterial wall that promotes disease progression and outcome, and immune cells play an important role in the inflammatory process.

Purpose

We review the mechanisms of CD4+ T subsets, i.e., helper T17 (Th17) cells and regulatory T cells (Tregs), in regulating atherosclerosis, focusing on the role of interleukin (IL)-17, IL-10, and other cytokines in this disease and the factors influencing the effects of these cytokines.

Results

IL-17 secreted by Th17 cells can promote atherosclerosis, but few studies have reported that IL-17 can also stabilize atherosclerotic plaques. Tregs play a protective role in atherosclerosis, and Th17/Treg imbalance also plays an important role in atherosclerosis.

Conclusion

The immune response is important in regulating atherosclerosis, and studying the mechanism of action of each immune cell on atherosclerosis presents directions for the treatment of atherosclerosis. Nevertheless, the current studies are insufficient for elucidating the mechanism of action, and further in-depth studies are needed to provide a theoretical basis for clinical drug development.

Xiaoyao-Qingluoyin Cure Adjuvant-Induced Arthritis by Easing LPS Response-Related Pathway-Mediated Immune Abnormality

Qingluoyin (QLY) is a representative herbal formula prescribed for hot symptom-related rheumatoid arthritis treatment. Among its derivatives, Xiaoyao-Qingluoyin (XYQLY) attracts increasing attention due to the notable clinical efficacy. In this study, we compared its effects with QLY on adjuvant-induced arthritis (AIA) in rats and partially elucidated the antirheumatic mechanism using a network pharmacology-based strategy. After continuous oral treatments, clinical outcomes were systematically evaluated by radiographic, histological, immunohistochemical, and serological analyses. Possibly altered pathways were predicted based on reported interactions between the related chemicals and proteins/genes. The obtained conclusion was further validated by experiments in vitro. QLY and XYQLY eased polyarthritis in AIA rats after repeated doses, which reflected in reduced inflammation and bone degradation and downregulated p-p65, MMP3, and TLR4 expressions in joints. Meanwhile, they restored oxidative stress (MDA, SOD, GSH, T-AOC, and NO) and inflammatory indicators (TNF-α and CO) in serum. Synovium-based immunoblotting assay revealed that QLY and XYQLY were similarly effective in downregulating MMP3 and COX-2, but XYQLY treatment exhibited notable merit in suppressing p-p65 expression. Network pharmacology analysis hinted that XYQLY should exert greater impacts on LPS signaling and the downstream. Based on results from LC-MS analysis, we treated AIA rat-derived peripheral blood mononuclear cells with either QLY or XYQLY-based chemical combinations and confirmed that XYQLY had the better potential in inhibiting TLR4/NF-κB-controlled IL-6 production. Consequently, it led to a more profound decrease in Th17 cells counts. Overall evidence demonstrated that XYQLY was especially effective in regulating innate immunity and, therefore, improved immune environment in AIA rats as a whole.

DEC1 negatively regulates CYP2B6 expression by binding to the CYP2B6 promoter region ascribed to IL-6-induced downregulation of CYP2B6 expression in HeLa cells

The cytochrome P450 superfamily (CYPs) is a group of metabolic enzymes involved in drug biotransformation/metabolism. It is the most important drug metabolic enzyme; however, its mechanism of action remains unclear.We investigated the expression of CYP2B6 in HeLa cells induced by interleukin-6 (IL-6) and explored the relationship between differentially expressed chondrocytes 1 (DEC1) and CYP2B6 via luciferase reporter, chromatin immunoprecipitation (ChIP) and ELISA assays.We observed the expression of CYP2B6 in HeLa cells exhibited a time-dependent decrease under the effect of IL-6, and the expression of CYP2B6 down-regulated by IL-6was negatively correlated with DEC1. After overexpression or knockdown of DEC1 in HeLa cells, the expression of CYP2B6 decreased or increased. The luciferase reporter assay and ChIP assay confirmed that DEC1 inhibited the expression of CYP2B6 by binding to the CYP2B6 promoter. ELISA results showed that high expression of DEC1 or low expression of CYP2B6 can promote the secretion of IL-6 in HeLa cells, and the secreted IL-6 can continually downregulate the expression of CYP2B6 in HeLa cells.Our results indicate that DEC1/CYP2B6 pathway in the inflammatory environment of tumours, and this provides a small amount of theoretical basis for the study of genes encoding drug-metabolising enzymes.

T regulatory cells as a potential therapeutic target in psychosis? Current challenges and future perspectives

Many studies have reported that patients with psychosis, even before drug treatment, have mildly raised levels of blood cytokines relative to healthy controls. In contrast, there is a remarkable scarcity of studies investigating the cellular basis of immune function and cytokine changes in psychosis. The few flow-cytometry studies have been limited to counting the proportion of the major classes of monocyte and lymphocytes without distinguishing their pro- and anti-inflammatory subsets. Moreover, most of the investigations are cross-sectional and conducted with patients on long-term medication. These features make it difficult to eliminate confounding of illness-related changes by lifestyle factors, disease duration, and long exposure to antipsychotics. This article focuses on regulatory T cells (Tregs), cornerstone immune cells that regulate innate and adaptive immune forces and neuro-immune interactions between astrocytes and microglia. Tregs are also implicated in cardio-metabolic disorders that are common comorbidities of psychosis. We have recently proposed that Tregs are hypofunctional ('h-Tregs') in psychosis driven by our clinical findings and other independent research. Our h-Treg-glial imbalance hypothesis offers a new account for the co-occurrence of systemic immune dysregulation and mechanisms of psychosis development. This article extends our recent review, the h-Treg hypothesis, to cover new discoveries on Treg-based therapies from pre-clinical findings and their clinical implications. We provide a detailed characterisation of Treg studies in psychosis, identifying important methodological limitations and perspectives for scientific innovation. The outcomes presented in this article reaffirms our proposed h-Treg state in psychosis and reveals emerging preclinical research suggesting the potential benefit of Treg-enhancing therapies. There is a clear need for longitudinal studies conducted with drug-naïve or minimally treated patients using more sophisticated techniques of flow-cytometry, CyTOF expression markers, and in vitro co-culture assays to formally test the suppressive capacity of Tregs. Investment in Treg research offers major potential benefits in targeting emerging immunomodulatory treatment modalities on person-specific immune dysregulations.

Crosstalk of Microorganisms and Immune Responses in Autoimmune Neuroinflammation: A Focus on Regulatory T Cells

Regulatory T cells (Tregs) are the major determinant of peripheral immune tolerance. Many Treg subsets have been described, however thymus-derived and peripherally induced Tregs remain the most important subpopulations. In multiple sclerosis, a prototypical autoimmune disorder of the central nervous system, Treg dysfunction is a pathogenic hallmark. In contrast, induction of Treg proliferation and enhancement of their function are central immune evasion mechanisms of infectious pathogens. In accordance, Treg expansion is compartmentalized to tissues with high viral replication and prolonged in chronic infections. In friend retrovirus infection, Treg expansion is mainly based on excessive interleukin-2 production by infected effector T cells. Moreover, pathogens seem also to enhance Treg functions as shown in human immunodeficiency virus infection, where Tregs express higher levels of effector molecules such as cytotoxic T-lymphocyte-associated protein 4, CD39 and cAMP and show increased suppressive capacity. Thus, insights into the molecular mechanisms by which intracellular pathogens alter Treg functions might aid to find new therapeutic approaches to target central nervous system autoimmunity. In this review, we summarize the current knowledge of the role of pathogens for Treg function in the context of autoimmune neuroinflammation. We discuss the mechanistic implications for future therapies and provide an outlook for new research directions.

Dysfunctions, Molecular Mechanisms, and Therapeutic Strategies of Regulatory T Cells in Rheumatoid Arthritis

Regulatory T cells (Tregs) represent a distinct subpopulation of CD4⁺ T lymphocytes that promote immune tolerance and maintain immune system homeostasis. The dysfunction of Tregs is tightly associated with rheumatoid arthritis (RA). Although the complex pathogenic processes of RA remain unclear, studies on Tregs in RA have achieved substantial progress not only in fundamental research but also in clinical application. This review discusses the current knowledge of the characterizations, functions, and molecular mechanisms of Tregs in the pathogenesis of RA, and potential therapies for these disorders are also involved.

Influence of Prednisone on Inflammatory Biomarkers in Community-Acquired Pneumonia: Secondary Analysis of a Randomized Trial

Glucocorticoids are frequently prescribed in inflammatory diseases and have recently experienced a boom in the treatment of COVID-19. Small studies have shown an effect of glucocorticoids on inflammatory marker levels, but definitive proof is lacking. We investigated the influence of prednisone on inflammatory biomarkers in a previous multicenter, randomized, placebo-controlled trial that compared a 7-day treatment course of 50-mg prednisone to placebo in patients hospitalized with community-acquired pneumonia. We compared levels of C-reactive protein (CRP), procalcitonin (PCT), leukocyte and neutrophil count between patients with and without glucocorticoid treatment at baseline and on days 3, 5, and 7 and at discharge by Wilcoxon tests and analysis of variance. A total of 356 patient data sets in the prednisone group and 355 in the placebo group were available for analysis. Compared to placebo, use of prednisone was associated with reductions in levels of CRP on days 3, 5, and 7 (mean difference of 46%, P < .001 for each time point). For PCT, no such difference was observed. Leukocyte and neutrophil count were higher in the prednisone group at all time points (mean difference of 27% for leukocytes and 33% for neutrophils, P <.001 for all time points). We conclude that after administration of glucocorticoids in community-acquired pneumonia, patients had lower CRP levels and increased leukocyte and neutrophil count as compared to the placebo group. PCT levels were not different between treatment groups. PCT levels thus may more appropriately mirror the resolution of infection compared to more traditional inflammatory markers.

Temperature Plays an Essential Regulatory Role in the Tumor Immune Microenvironment

In recent years, emerging immunotherapy has been included in various malignant tumor treatment standards. Temperature has been considered to affect different pathophysiological reactions such as inflammation and cancer for a long time. However, in tumor immunology research, temperature is still rarely considered a significant variable. In this review, we discuss the effects of room temperature, body temperature, and the local tumor temperature on the tumor immune microenvironment from multiple levels and perspectives, and we discuss changes in the body's local and whole-body temperature under tumor conditions. We analyze the current use of ablation treatment-the reason for the opposite immune effect. We should pay more attention to the therapeutic potential of temperature and create a better antitumor microenvironment that can be combined with immunotherapy.

Present Status and Future Trends of Natural-Derived Compounds Targeting T Helper (Th) 17 and Microsomal Prostaglandin E Synthase-1 (mPGES-1) as Alternative Therapies for Autoimmune and Inflammatory-Based Diseases

Several natural-based compounds and products are reported to possess anti-inflammatory and immunomodulatory activity both in vitro and in vivo. The primary target for these activities is the inhibition of eicosanoid-generating enzymes, including phospholipase A2, cyclooxygenases (COXs), and lipoxygenases, leading to reduced prostanoids and leukotrienes. Other mechanisms include modulation of protein kinases and activation of transcriptases. However, only a limited number of studies and reviews highlight the potential modulation of the coupling enzymatic pathway COX-2/mPGES-1 and Th17/Treg circulating cells. Here, we provide a brief overview of natural products/compounds, currently included in the Italian list of botanicals and the BELFRIT, in different fields of interest such as inflammation and immunity. In this context, we focus our opinion on novel therapeutic targets such as COX-2/mPGES-1 coupling enzymes and Th17/Treg circulating repertoire. This paper is dedicated to the scientific career of Professor Nicola Mascolo for his profound dedication to the study of natural compounds.

Flaccidoside II ameliorates collagen-induced arthritis in mice

Flaccidoside II (FLA II), the primary active constituent from Anemone flaccida rhizome, was proven to exert therapeutic effect against collagen-induced arthritis (CIA). In this study, a research based on the CIA mouse model was carried out in order to elucidate its therapeutic mechanisms preliminarily. The mice were immunized with porcine type-II collagen to induce CIA and administrated intragastrically with FLA II daily from day 7-42 of the first collagen immunization. The arthritis scores as reflected by the severity of paw swelling and erythema were significantly reduced in FLA II (32 mg/kg) from day 33 onwards. On day 42, the joints of FLA II-treated mice exhibited obvious reductions of inflammatory cells infiltration, synovial hyperplasia and bone destruction. When the concentration of FLA II was no less than 40 nmol/ml, the treatment notably inhibited T and B lymphocyte proliferative responses. As compared to the model group, in FLA II groups, the serum levels of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) were significantly decreased while those of Th2 type cytokines (IL-4 and IL-10) were clearly enhanced. In addition, FLA II treatment showed little regulatory effect on the levels of Th1 type cytokines (IFN-γ and IL-2). The severity of mice CIA was improved by FLA II, further confirming its potential value for the safe treatment of rheumatoid arthritis. The main mechanisms likely involve the inhibition of lymphocyte proliferation and pro-inflammatory cytokine secretion, and the modulation of Th1/Th2-related cytokine balance in CIA.

Dawn of Monitoring Regulatory T Cells in (Pre-)clinical Studies: Their Relevance Is Slowly Recognised

Regulatory T cells (Tregs) have a prominent role in the control of immune homeostasis. Pharmacological impact on their activity or balance with effector T cells could contribute to (impaired) clinical responses or adverse events. Monitoring treatment-related effects on T cell subsets may therefore be part of (pre-)clinical studies for medicinal products. However, the extent of immune monitoring performed in studies for marketing authorisation and the degree of correspondence with data available in the public domain is not known. We evaluated the presence of T cell immunomonitoring in 46 registration dossiers of monoclonal antibodies indicated for immune-related disorders and published scientific papers. We found that the depth of Treg analysis in registration dossiers was rather small. Nevertheless, data on treatment-related Treg effects are available in public academia-driven studies (post-registration) and suggest that Tregs may act as a biomarker for clinical responses. However, public data are fragmented and obtained with heterogeneity of experimental approaches from a diversity of species and tissues. To reveal the potential added value of T cell (and particular Treg) evaluation in (pre-)clinical studies, more cell-specific data should be acquired, at least for medicinal products with an immunomodulatory mechanism. Therefore, extensive analysis of T cell subset contribution to clinical responses and the relevance of treatment-induced changes in their levels is needed. Preferably, industry and academia should work together to obtain these data in a standardised manner and to enrich our knowledge about T cell activity in disease pathogenesis and therapies. This will ultimately elucidate the necessity of T cell subset monitoring in the therapeutic benefit-risk assessment.

Role of Foxp3/Treg and RORγt/Th17 imbalance in chronic hepatitis B virus infection

A wide range of immune-mediated liver damage can be seen during infection with hepatitis B virus (HBV). Failure of HBV immune clearance leads to chronic hepatitis and greatly increases the risk of liver cirrhosis and hepatocellular carcinoma. Recently, there have been many studies on the relationship between the outcome of HBV infection and the immune status of patients. The immune response of T lymphocytes in HBV infection plays an important role, especially the imbalance of regulatory T cells (Treg)/Helper T cell 17 (Th17). The imbalance between the Treg and Th17 is an important mechanism of persistent HBV infection and inflammatory injury of the liver. To better reveal the underlying mechanisms, we systematically review the roles of Treg and Th17 and discuss the relationship between Treg and Th17 during HBV infection as well as the changes in the two related specific transcription factors, retinoid-related orphan nuclear receptor γt (RORγt) and forkhead/winged helix family transcription factor 3 (Foxp3). The research on HBV immunotargeting therapy in recent years has suggested the role of Foxp3/Treg and RORγt/Th17 imbalance in HBV infection. Such findings provide new ideas for the treatment of chronic hepatitis B.

Enhanced neutrophil autophagy and increased concentrations of IL-6, IL-8, IL-10 and MCP-1 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a high morbidity and disability disease with numerous inflammatory cells infiltrating in interstitial of articular cartilages and bones. As the most abundant inflammatory cells, neutrophil has been reported that their apoptosis changed gradually in the circumstance of RA. Apoptosis, one modality of programmed cell death (PCD), is closely associated with autophagy, which indicates neutrophil autophagy may also alter in RA. Flow cytometry, western blotting, immunohistochemistry, immunofluorescence, transmission electron microscope and multiplex antibody microarray were used to comparative investigate the status of neutrophil autophagy in patients with RA and in vitro. The results showed that the expression of autophagy related LC3 protein was up-regulated with lower lysosomal pH in neutrophils from synovial fluid of RA and changed under stimulation of CQ and small RNA interferences (siRNAs) Atg5 transfection, which proved in acute promyelocytic leukemia HL-60 cell lines, predominantly a neutrophilic promyelocyte, treated by plasma and synovial fluid from RA. We further found out the concentration of IL-6, IL-8, IL-10 and MCP-1 was higher in their synovial fluid which may mediate neutrophil autophagy in RA via cytokine-cytokine receptor interaction and IL-17 signaling pathway. Our results indicate that neutrophil autophagy may be a novel perspective to understand the pathology which may provide a new maker to diagnose RA and IL-8, IL-10, MCP-1 specific antagonists and neutrophil autophagy target inhibitors may improve the therapeutic effect of RA someday.

The pleiotropic role of interleukin-17 in atherosclerosis

Atherosclerosis is the main cause of cardiovascular diseases (CVDs), which considers the leading cause of mortality worldwide. Atherosclerosis is a chronic inflammatory condition of arterials' wall in which the development and the destabilization of plaque occur. Both innate and adaptive immunity play a significant role in modifying lipoproteins in arterials' wall. Recent investigations have demonstrated the opposing roles of CD4⁺ T cells subtypes in atherosclerosis. T helper-1 (Th1) response and pro-inflammatory cytokines possess proatherogenic effects, whereas T regulatory (Treg) cells have an atheroprotective role. Th17 cells have emerged as a new CD4⁺ T-cell subtype, which produce IL-17 that plays a crucial role in numerous inflammatory and autoimmune diseases. Recently, several studies have investigated the potential role of IL-17 in atherosclerosis. Some investigations have suggested a proatherogenic effect, however the others proposed an atheroprotective role. Hence, the exact role of IL-17 in the disease development and plaque stability is still debatable. In this review, we summarize the current knowledge on both atherogenesis and atheroprotective roles of IL-17. In addition, the synergistic and antagonistic effects of IL-17 with other cytokines in atherosclerosis will be discussed. On the basis of the current understanding of these roles, the possibility of developing novel therapeutic strategies against atherosclerosis may be evolved.

Interleukin-6 as a "metabolic hormone"

Interleukin 6 (IL-6) is a cytokine that is involved in divers immune responses and implicated in a number of diseases. However, this cytokine has other non-immune functions. Within this review, we highlight selected effects on metabolic pathways, which are mediated, controlled or modified by the IL-6. Importantly, putting spotlight on such concepts could allow us to classify IL-6 among the metabolic hormones and further study it to both deepen our knowledge on disorders involving metabolic or energy imbalances such as obesity and develop novel therapeutic strategies. Furthermore, potential explanations related to IL-6 roles in both physiology and pathology as well as relevant implications and applications on both research and therapeutic fields are also pointed as consequences of the involvement of IL-6 in the energy and metabolic homeostasis via its "endocrine" roles.

Anti-Inflammatory Effects of HDL in Mice With Rheumatoid Arthritis Induced by Collagen

Objective

To investigate the anti-inflammatory effects of high-density lipoprotein (HDL) in mice with rheumatoid arthritis (RA) induced by collagen.

Methods

Male DBA/1 mice (8-week-old) were divided into three groups: control (treated with saline), collagen-induced arthritis (CIA), and CIA + HDL. CIA was induced with bovine type II collagen, and after the injection of bovine type II collagen, the CIA + HDL group received an injection of HDL on day 28 followed by HDL injections four times every 3 days. Mice were weighed, the paws were scored, and paw thickness was measured beginning on day 21. Additionally, the levels of tumor necrosis factor-alpha (TNF-α) and IL-6 were measured by ELISA kits, tissue sections of paws were stained with hematoxylin and eosin, and the inflammatory signaling pathway was analyzed by western blotting.

Results

We found that the production of pro-inflammatory cytokines TNF-α and IL-6 in mice which received HDL decreased 45.14 and 35.02%, respectively. And we also found that HDL could significantly decrease the level of anti-type-II-collagen IgG2a and inhibit the neutrophil infiltration and cell proliferation and protect the ankle joint from type II collage-induced injury. Western blot analysis indicated that HDL could also inhibit the activation of the NF-κB, MAPK, and ERK signaling pathways in RA mice.

Conclusion

HDL can inhibit the inflammation induced by bovine type II collagen and the development of RA.

The Balance of Th17 versus Treg Cells in Autoimmunity

T helper type 17 (Th17) cells and pTreg cells, which share a common precursor cell (the naïve CD4 T cell), require a common tumor growth factor (TGF)-β signal for initial differentiation. However, terminally differentiated cells fulfill opposite functions: Th17 cells cause autoimmunity and inflammation, whereas Treg cells inhibit these phenomena and maintain immune homeostasis. Thus, unraveling the mechanisms that affect the Th17/Treg cell balance is critical if we are to better understand autoimmunity and tolerance. Recent studies have identified many factors that influence this balance; these factors range from signaling pathways triggered by T cell receptors, costimulatory receptors, and cytokines, to various metabolic pathways and the intestinal microbiota. This review article summarizes recent advances in our understanding of the Th17/Treg balance and its implications with respect to autoimmune disease.

Anti-Inflammatory Effects of p-Coumaric Acid, a Natural Compound of Oldenlandia diffusa, on Arthritis Model Rats

Objectives

In China, Oldenlandia diffusa (OD) is a natural herb that is widely used and has been proven to be effective in the treatment of rheumatoid arthritis (RA). This study aimed to preliminarily reveal the mechanism by which OD exerts its beneficial effect.

Methods

Ultra-performance liquid chromatography photodiode array was applied to identify the absorbable compounds in the plasma of collagen-induced arthritis (CIA) model rats. After 2 weeks, an OD decoction or the identified absorbable compound was administered to CIA rats. Morphology, X-ray images of the joints, pathological images, arthritis index, and cytokine (TNF-α and IL-6) levels were evaluated.

Results

p-Coumaric acid (p-CA) was identified as the absorbed compound in plasma. After administration of p-CA solution or the OD decoction, symptoms in the treated rats were alleviated as compared to the untreated model rats, and inflammatory cell infiltration was suppressed. The arthritis index and serum levels of TNF-α and IL-6 were decreased as compared to the control group.

Conclusions

OD may exert its anti-inflammatory effect on RA via its active ingredient, p-CA. This information sheds light on the mechanism by which OD exerts its anti-inflammatory effort in RA and forms the basis for further development of therapeutic agents for RA.

Leptin-induced migration and angiogenesis in rheumatoid arthritis is mediated by reactive oxygen species

Rheumatoid arthritis (RA) is a progressive autoimmune disease affecting the joints. In this study, we investigated the role of the pro‐angiogenic factor leptin in regulating reactive oxygen species (ROS) to promote cell migration and angiogenesis in RA. We showed that leptin triggered RA fibroblast‐like synoviocyte (FLS) migration by increased ROS expression. Additionally, leptin enhanced human umbilical vein endothelial cell (HUVEC) tube formation in a ROS/hypoxia‐inducible factor‐1α‐dependent manner, accompanied by increased production of vascular endothelial growth factor and interleukin (IL)‐6. We also revealed that antagonists of tumor necrosis factor, IL‐6 and IL‐1β down‐regulated ROS production of RA FLS induced by leptin, which subsequently attenuated RA FLS migration and HUVEC tube formation. These findings demonstrated that leptin might play an important role in RA FLS migration and HUVEC angiogenesis.

PTEN drives Th17 cell differentiation by preventing IL-2 production

Th17 cells mediate inflammation and autoimmunity. Although it was known that cytokine IL-2 inhibits Th17 cell differentiation, how it does so was elusive. Using IL-17–specific PTEN-deficient mice, Kim et al. show that phosphatase PTEN inhibits IL-2 production and thus promotes Th17 cell differentiation.

T helper 17 (Th17) cells are a CD4⁺ T cell subset that produces IL-17A to mediate inflammation and autoimmunity. IL-2 inhibits Th17 cell differentiation. However, the mechanism by which IL-2 is suppressed during Th17 cell differentiation remains unclear. Here, we show that phosphatase and tensin homologue (PTEN) is a key factor that regulates Th17 cell differentiation by suppressing IL-2 production. Th17-specific Pten deletion (Pten^fl/flIl17a^cre) impairs Th17 cell differentiation in vitro and ameliorated symptoms of experimental autoimmune encephalomyelitis (EAE), a model of Th17-mediated autoimmune disease. Mechanistically, Pten deficiency up-regulates IL-2 and phosphorylation of STAT5, but reduces STAT3 phosphorylation, thereby inhibiting Th17 cell differentiation. PTEN inhibitors block Th17 cell differentiation in vitro and in the EAE model. Thus, PTEN plays a key role in Th17 cell differentiation by blocking IL-2 expression.

Therapeutic Potential of Targeting the Th17/Treg Axis in Autoimmune Disorders

A disruption of the crucial balance between regulatory T-cells (Tregs) and Th17-cells was recently implicated in various autoimmune disorders. Tregs are responsible for the maintenance of self-tolerance, thus inhibiting autoimmunity, whereas pro-inflammatory Th17-cells contribute to the induction and propagation of inflammation. Distortion of the Th17/Treg balance favoring the  pro-inflammatory Th17 side is hence suspected to contribute to exacerbation of autoimmune disorders. This review aims to summarize recent data and advances in targeted therapeutic modification of the Th17/Treg-balance, as well as information on the efficacy of candidate therapeutics with respect to the treatment of autoimmune diseases.