Changsheng Du

MicroRNA miR-326 regulates T H -17 differentiation and is associated with the pathogenesis of multiple sclerosis

Interleukin 17 (IL-17)-producing T helper cells (TH-17 cells) are increasingly recognized as key participants in various autoimmune diseases, including multiple sclerosis. Although sets of transcription factors and cytokines are known to regulate TH-17 differentiation, the role of noncoding RNA is poorly understood. Here we identify a TH-17 cell–associated microRNA, miR-326, whose expression was highly correlated with disease severity in patients with multiple sclerosis and mice with experimental autoimmune encephalomyelitis (EAE). In vivo silencing of miR-326 resulted in fewer TH-17 cells and mild EAE, and its overexpression led to more TH-17 cells and severe EAE. We also found that miR-326 promoted TH-17 differentiation by targeting Ets-1, a negative regulator of TH-17 differentiation. Our data show a critical role for microRNA in TH-17 differentiation and the pathogenesis of multiple sclerosis.

Blocking A2B Adenosine Receptor Alleviates Pathogenesis of Experimental Autoimmune Encephalomyelitis via Inhibition of IL-6 Production and Th17 Differentiation

Adenosine is a key endogenous signaling molecule that regulates immune responses. A2B adenosine receptor (AR) is a relatively low-affinity receptor for adenosine, and the activation of A2BAR is believed to require pathological level of adenosine that is associated with ischemia, inflammation, trauma, or other types of stress. The role of A2BAR in the pathogenesis of multiple sclerosis (MS) is still unclear. In this study, we discovered that A2BAR was upregulated both in the peripheral blood leukocytes of MS patients and the peripheral lymphoid tissues of experimental autoimmune encephalomyelitis (EAE) mice. A2BAR-specific antagonists, CVT-6883 and MRS-1754, alleviated the clinical symptoms of EAE and protected the CNS from immune damage. A2BAR-knockout mice also developed less severe EAE. Further study indicated that blocking or deleting A2BAR inhibited Th17 cell differentiation by blocking IL-6 production from APCs such as dendritic cells. In dendritic cells, A2BAR was also upregulated during the development of EAE. CVT-6883 and genetic deletion of A2BAR significantly reduced adenosine-mediated IL-6 production. The phospholipase Cβ–protein kinase C and p38 MAPK pathways were found to be involved in the A2BAR-mediated IL-6 production. Our findings not only revealed the pathological role of A2BAR in EAE, but also suggested that this receptor might be a new therapeutic target for the development of anti-MS drugs.

Antiasthmatic Drugs Targeting the Cysteinyl Leukotriene Receptor 1 Alleviate Central Nervous System Inflammatory Cell Infiltration and Pathogenesis of Experimental Autoimmune Encephalomyelitis

Cysteinyl leukotrienes (CysLTs) are potent proinflammatory mediators and are considered to play a key role in inflammatory diseases such as asthma. Antagonists targeting the receptor of CysLTs (CysLT1) are currently used as antiasthmatic drugs. CysLTs have also been implicated in other inflammatory reactions. In this study, we report that in experimental autoimmune encephalomyelitis animals, CysLT1 is upregulated in immune tissue and the spinal cord, and CysLT levels in the blood and cerebrospinal fluid are also higher than in normal mice. Two clinically used antiasthma drugs, montelukast and zafirlukast, both targeting CysLT1, effectively block the CNS infiltration of inflammatory cells and thus reduce the incidence, peak severity, and cumulative clinical scores. Further study indicated that CysLT1 signaling does not affect the differentiation of pathogenic T helper cells. It might affect the pathogenesis of experimental autoimmune encephalomyelitis by increasing the secretion of IL-17 from myelin oligodendrocyte glycoprotein-specific T cells, increasing the permeability of the blood–brain barrier and inducing chemotaxis of T cells. These effects can be blocked by CysLT1 antagonists. Our findings indicate that the antiasthmatic drugs against CysLT1 can also be used to treat multiple sclerosis.

G protein-coupled receptors as therapeutic targets for multiple sclerosis

G protein-coupled receptors (GPCRs) mediate most of our physiological responses to hormones, neurotransmitters and environmental stimulants. They are considered as the most successful therapeutic targets for a broad spectrum of diseases. Multiple sclerosis (MS) is an inflammatory disease that is characterized by immune-mediated demyelination and degeneration of the central nervous system (CNS). It is the leading cause of non-traumatic disability in young adults. Great progress has been made over the past few decades in understanding the pathogenesis of MS. Numerous data from animal and clinical studies indicate that many GPCRs are critically involved in various aspects of MS pathogenesis, including antigen presentation, cytokine production, T-cell differentiation, T-cell proliferation, T-cell invasion, etc. In this review, we summarize the recent findings regarding the expression or functional changes of GPCRs in MS patients or animal models, and the influences of GPCRs on disease severity upon genetic or pharmacological manipulations. Hopefully some of these findings will lead to the development of novel therapies for MS in the near future.

The antiepileptic drug valproic acid restores T cell homeostasis and ameliorates pathogenesis of experimental autoimmune encephalomyelitis

Background: Dysregulation of T cell survival and apoptosis is the common cause of autoimmune diseases including multiple sclerosis (MS). Results: Valproic acid (VPA) treatment restores the dysregulated apoptosis of T cells and reduces the symptoms of EAE. Conclusion: In addition to the antiepileptic activity, VPA also regulates T cell homeostasis. Significance: As an orally available drug, VPA might be used to treat autoimmune diseases, such as MS. Maintaining a constant number and ratio of immune cells is one critical aspect of the tight regulation of immune homeostasis. Breakdown of this balance will lead to autoimmune diseases such as multiple sclerosis (MS). The antiepileptic drug valproic acid (VPA) was reported to regulate the growth, survival, and differentiation of many cells. However, its function in T cell homeostasis and MS treatment remains unknown. In this study, VPA was found to reduce spinal cord inflammation, demyelination, and disease scores in experimental autoimmune encephalomyelitis, a mouse model of MS. Further study indicated that VPA induces apoptosis in activated T cells and maintains the immune homeostasis. This effect was found to be mainly mediated by the caspase-8/caspase-3 pathway. Interestingly, this phenomenon was also confirmed in T cells from normal human subjects and MS patients. Considering the long history of clinical use and our new findings, we believe VPA might be a safe and effective therapy for autoimmune diseases, such as multiple sclerosis.

Kappa opioid receptor activation alleviates experimental autoimmune encephalomyelitis and promotes oligodendrocyte-mediated remyelination

Multiple sclerosis (MS) is characterized by autoimmune damage to the central nervous system. All the current drugs for MS target the immune system. Although effective in reducing new lesions, they have limited effects in preventing the progression of disability. Promoting oligodendrocyte-mediated remyelination and recovery of neurons are the new directions of MS therapy. The endogenous opioid system, consisting of MOR, DOR, KOR and their ligands, has been suggested to participate in the pathogenesis of MS. However, the exact receptor and mechanism remain elusive. Here we show that genetic deletion of KOR exacerbates experimental autoimmune encephalomyelitis, whereas activating KOR with agonists alleviates the symptoms. KOR does not affect immune cell differentiation and function. Instead, it promotes oligodendrocyte differentiation and myelination both in vitro and in vivo. Our study suggests that targeting KOR might be an intriguing way to develop new MS therapies that may complement the existing immunosuppressive approaches.

Magnesium Lithospermate B Protects Cardiomyocytes from Ischemic Injury Via Inhibition of TAB1–p38 Apoptosis Signaling

Danshen has been used in traditional Chinese medicine for hundreds of years to treat cardiovascular diseases. However, its precise cardioprotective components and the underlying mechanism are still unclear. In the present study, we demonstrated that in a rat model of acute myocardial infarction, the treatment with magnesium lithospermate B (MLB), the representative component of phenolic acids in Danshen, significantly reduced the infarct size and the blood lactate dehydrogenase level. In contrast, tanshinone IIA, the representative component of lipophilic tanshinones in Danshen, had no such protective effects. Moreover, in the simulated ischemia cell model, MLB treatment considerably increased the cell viability and reduced the sub-G1 population and the apoptotic nuclei, indicating its anti-apoptotic effect. Further mechanism study revealed that the ischemia-induced p38 phosphorylation was abolished by MLB treatment. Interestingly, MLB specifically inhibited the TGFβ-activated protein kinase 1-binding protein 1 (TAB1) mediated p38 phosphorylation through disrupting the interaction between TAB1 and p38, but it did not affect the mitogen-activated protein kinase 3/6 mediated p38 phosphorylation. In conclusion, the present study identifies MLB as an active component of Danshen in protecting cardiomyocytes from ischemic injury through specific inhibition of TAB1–p38 apoptosis signaling. These results indicate TAB1–p38 interaction as a putative drug target in treating ischemic heart diseases.

Deficiency of the G protein Gαq ameliorates experimental autoimmune encephalomyelitis with impaired DC-derived IL-6 production and Th17 differentiation

Many G protein-coupled receptors (GPCRs) are reported to be involved in the pathogenesis of multiple sclerosis (MS), and ~40% of all identified GPCRs rely on the Gαq/11 G protein family to stimulate inositol lipid signaling. However, the function of Gα subunits in MS pathogenesis is still unknown. In this study, we attempted to determine the role of Gαq in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a well-known mouse model of MS. We discovered that compared with wild-type mice, Gαq-knockout mice exhibited less severe EAE symptoms, with lower clinical scores, reduced leukocyte infiltration and less extensive demyelination. Moreover, a significantly lower percentage of Th17 cells, one of the key players in MS pathogenesis, was observed in Gαq-knockout EAE mice. Studies in vitro demonstrated that deficiency of Gαq in CD4+ T cells directly impaired Th17 differentiation. In addition, deficiency of Gαq significantly impaired DC-derived IL-6 production, thus inhibiting Th17 differentiation and the Gαq-PLCβ-PKC and Gαq-MAPKs signaling pathways involved in the reduced IL-6 production by DCs. In summary, our data highlighted the critical role of Gαq in regulating Th17 differentiation and MS pathogenesis.

The Spatio-Temporal Expression Profiles of CD4 + T Cell Differentiation and Function-Related Genes During EAE Pathogenesis

Multiple sclerosis is a CD4+ T cell-mediated autoimmune disease of the central nervous system. The unbalance of the cytokines and transcription factors critical for CD4+ T cell differentiation and function is probably the main reason that causes MS. We detected the mRNA expression changes of key cytokines and transcription factors which are critical for Th1, Th2, Th17, and Treg cell differentiation and function in different tissues during EAE pathogenesis. We fund that each gene not only has its own featured expression changes, but also has interaction with one another, which composes a network of immunity. Understanding the roles of key cytokines and transcription factors in these processes will help to understand disease pathogenesis and supply indications for disease therapy.

BLT1 in dendritic cells promotes Th1/Th17 differentiation and its deficiency ameliorates TNBS-induced colitis

Leukotriene B4 (LTB4) synthesis is enhanced in the colonic mucosa in patients with inflammatory bowel disease (IBD). BLT1, a high-affinity receptor for LTB4, exhibits no effect on the progression of dextran sodium sulfate (DSS)-induced colitis, which mostly relies on innate immunity. Here, we reported that BLT1 regulates trinitrobenzene sulfonic acid (TNBS)-induced colitis, which reflects CD4+ T-cell-dependent adaptive immune mechanisms of IBD. We found that BLT1 signaling enhanced the progression of colitis through controlling the production of proinflammatory cytokines by dendritic cells (DCs) and modulating the differentiation of Th1 and Th17. BLT1−/− mice displayed an alleviated severity of TNBS-induced colitis with reduced body weight loss and infiltrating cells in the lamina propria. BLT1 deficiency in DCs led to reduced production of proinflammatory cytokines, including IL-6, TNF-α, and IL-12, and these results were further confirmed via treatment with a BLT1 antagonist. The impaired cytokine production by BLT1−/− DCs subsequently led to reduced Th1 and Th17 differentiation both in vitro and in vivo. We further performed a conditional DC reconstitution experiment to assess whether BLT1 in DCs plays a major role in regulating the pathogenesis of TNBS-induced colitis, and the results indicate that BLT1 deficiency in DCs also significantly reduces disease severity. The mechanistic study demonstrated that BLT1-regulated proinflammatory cytokine production through the Gαi βγ subunit-phospholipase Cβ (PLCβ)-PKC pathway. Notably, we found that treatment with the BLT1 antagonist also reduced the production of proinflammatory cytokines by human peripheral blood DCs. Our findings reveal the critical role of BLT1 in regulating adaptive immunity and TNBS-induced colitis, which further supports BLT1 as a potential drug target for adaptive immunity-mediated IBD.