COX-2 inhibitors modulate IL-12 signaling through JAK-STAT pathway leading to Th1 response in experimental allergic encephalomyelitis

Systematic Review of Interleukin-35 in Endothelial Dysfunction: A New Target for Therapeutic Intervention

Endothelial dysfunction is a significant factor in the pathogenesis of various diseases. In pathological states, endothelial cells (ECs) undergo activation, resulting in dysfunction characterized by the stimulation of inflammatory responses, oxidative stress, cell proliferation, blood coagulation, and vascular adhesions. Interleukin-35 (IL-35), a novel member of the IL-12 family, is primarily secreted by regulatory T cells (Tregs) and regulatory B cells (Bregs). The role of IL-35 in immunomodulation, antioxidative stress, resistance to apoptosis, control of EC activation, adhesion, and angiogenesis in ECs remains incompletely understood, as the specific mechanisms of IL-35 action and its regulation have yet to be fully elucidated. Therefore, this systematic review aims to comprehensively investigate the impact of IL-35 on ECs and their physiological roles in a range of conditions, including cardiovascular diseases, tumors, sepsis, and rheumatoid arthritis (RA), with the objective of elucidating the potential of IL-35 as a therapeutic target for these ailments.

Ameliorative effect of Alangium chinense (Lour.) Harms on rheumatoid arthritis by reducing autophagy with targeting regulate JAK3-STAT3 and COX-2 pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Alangium chinense has been used as traditional folk medicine for centuries to treat rheumatoid arthritis (RA) by Guizhou Miao nationality with remarkable clinical effect. But the mechanism of its anti-RA is not fully clarified.

AIM OF THE STUDY

To explore the effect and underlying mechanism of A. chinense against RA.

MATERIAL AND METHODS

RA rats were induced by CII/IFA, and oral administrated with or without ethyl acetate extracts of Alangium chinense (ACEE) and tripterygium glycosides (GTW). Then arthritis scores, inflammatory factors in serum and histological evaluation were evaluated to assess the degree of joints disease. Proteomics were conducted via LC-MS/MS to clarify the mechanism of ACEE preliminarily, and further examined by immunohistochemistry, immunofluorescence, western botting, and molecular docking.

RESULTS

ACEE decreased joints swelling, cell abscission and necrosis of joint tissues arthropathy of RA rats, and attenuated expression of TNF-α, IL-1β, IL-6, PGE2, TGF-β. Meanwhile, differentially expressed proteins in the ACEE treated groups were observed, which were involved in RA, spliceosome, cell adhesion molecules, phagosome and lysosome signaling pathways. Moreover, ACEE significantly ameliorated arthropathy, suppressed JAK-STAT pathway (JAK3, p-JAK3, STAT3, iNOS, RANKL), COX-2 pathway (COX-2, TNF-α, IL-6I, L-1β, 5-LOX), and autophagic signaling pathway (LC3-Ⅰ, LC3-Ⅱ, p62, mTOR). But it showed little effect on the expression of COX-1, JAK1, JAK2, TyK2.

CONCLUSION

It is the first evidence that A. chinense significantly ameliorates RA, and the underlying immune mechanism involves reducing autophagy with targeting regulate JAK3-STAT3 and COX-2 pathways.

JAK-STAT Signaling Pathway in Non-Infectious Uveitis

Non-infectious uveitis (NIU) refers to various intraocular inflammatory disorders responsible for severe visual loss. Cytokines participate in the regulation of ocular homeostasis and NIU pathological processes. Cytokine receptors transmit signals by activating Janus kinase (JAK) and signal transducer and activator of transcription (STAT) proteins. Increasing evidence from human NIU and experimental models reveals the involvement of the JAK-STAT signaling pathway in NIU pathogenesis. Several small-molecule drugs that potentially inhibit multiple cytokine-dependent pathways are under investigation for treating autoimmune diseases, implicating possible applications for NIU treatment. This review summarizes the current understanding of the diverse roles of the JAK-STAT signaling pathway in ocular homeostasis and NIU pathology, providing a rationale for targeting JAKs and STATs for NIU treatment. Moreover, available evidence for the safety and efficacy of JAK inhibitors for refractory uveitis and potential approaches for treatment optimization are discussed.

Non-coding RNAs regulation of macrophage polarization in cancer

Noncoding RNA (ncRNA) transcripts that did not code proteins but regulate their functions were extensively studied for the last two decades and the plethora of discoveries have instigated scientists to investigate their dynamic roles in several diseases especially in cancer. However, there is much more to learn about the role of ncRNAs as drivers of malignant cell evolution in relation to macrophage polarization in the tumor microenvironment. At the initial stage of tumor development, macrophages have an important role in directing Go/No-go decisions to the promotion of tumor growth, immunosuppression, and angiogenesis. Tumor-associated macrophages behave differently as they are predominantly induced to be polarized into M2, a pro-tumorigenic type when recruited with the tumor tissue and thereby favoring the tumorigenesis. Polarization of macrophages into M1 or M2 subtypes plays a vital role in regulating tumor progression, metastasis, and clinical outcome, highlighting the importance of studying the factors driving this process. A substantial number of studies have demonstrated that ncRNAs are involved in the macrophage polarization based on their ability to drive M1 or M2 polarization and in this review we have described their functions and categorized them into oncogenes, tumor suppressors, Juggling tumor suppressors, and Juggling oncogenes.

A Systematic Review on the Role of Arachidonic Acid Pathway in Multiple Sclerosis

BACKGROUND & OBJECTIVE

Multiple sclerosis (MS) is an inflammatory neurodegenerative disease characterized by destruction of oligodendrocytes, immune cell infiltration and demyelination. Inflammation plays a significant role in MS, and the inflammatory mediators such as eicosanoids, leukotrienes, superoxide radicals are involved in pro-inflammatory responses in MS. In this systematic review we tried to define and discuss all the findings of in vivo animal studies and human clinical trials on the potential association between arachidonic acid (AA) pathway and multiple sclerosis.

METHODS

A systematic literature search across Pubmed, Scopus, Embase and Cochrane database was conducted. This systematic review was performed according to PRISMA guidelines.

RESULTS

A total of 146 studies were included, of which 34 were conducted in animals, 58 in humans, and 60 studies reported the role of different compounds that target AA mediators or their corresponding enzymes/ receptors, and can have a therapeutic effect in MS. These results suggest that eicosanoids have significant roles in experimental autoimmune encephalomyelitis (EAE) and MS. The data from animal and human studies elucidated that PGI2, PGF2α, PGD2, isoprostanes, PGE2, PLA2, LTs are increased in MS. PLA2 inhibition modulates the progression of the disease. PGE1 analogues can be a useful option in the treatment of MS.

CONCLUSIONS

All studies reported the beneficial effects of COX and LOX inhibitors in MS. The hybrid compounds, such as COX-2 inhibitors/TP antagonists and 5-LOX inhibitors can be an innovative approach for multiple sclerosis treatment. Future work in MS should shed light in synthesizing new compounds targeting arachidonic acid pathway.

Deletion of Arginase 2 Ameliorates Retinal Neurodegeneration in a Mouse Model of Multiple Sclerosis

Optic neuritis is a major clinical feature of multiple sclerosis (MS) and can lead to temporary or permanent vision loss. Previous studies from our laboratory have demonstrated the critical involvement of arginase 2 (A2) in retinal neurodegeneration in models of ischemic retinopathy. The current study was undertaken to investigate the role of A2 in MS-mediated retinal neuronal damage and degeneration. Experimental autoimmune encephalomyelitis (EAE) was induced in wild-type (WT) and A2 knockout (A2^-/-) mice. EAE-induced motor deficits, loss of retinal ganglion cells, retinal thinning, inflammatory signaling, and glial activation were studied in EAE-treated WT and A2^-/- mice and their respective controls. Increased expression of A2 was observed in WT retinas in response to EAE induction. EAE-induced motor deficits were markedly reduced in A2^-/- mice compared with WT controls. Retinal flat mount studies demonstrated a significant reduction in the number of RGCs in WT EAE retinas in comparison with normal control mice. A significant improvement in neuronal survival was evident in retinas of EAE-induced A2^-/- mice compared with WT. RNA levels of the proinflammatory molecules CCL2, COX2, IL-1α, and IL-12α were significantly reduced in the A2^-/- EAE retinas compared with WT EAE. EAE-induced activation of glia (microglia and Müller cells) was markedly reduced in A2^-/- retinas compared with WT. Western blot analyses showed increased levels of phospho-ERK1/2 and reduced levels of phospho-BAD in the WT EAE retina, while these changes were prevented in A2^-/- mice. In conclusion, our studies establish EAE as an excellent model to study MS-mediated retinal neuronal damage and suggest the potential value of targeting A2 as a therapy to prevent MS-mediated retinal neuronal injury.

Endothelial Microsomal Prostaglandin E Synthetase-1 Upregulates Vascularity and Endothelial Interleukin-1β in Deteriorative Progression of Experimental Autoimmune Encephalomyelitis

Microsomal prostaglandin E synthetase-1 (mPGES-1) is an inducible terminal enzyme for the production of prostaglandin E₂ (PGE₂). In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, mPGES-1 is induced in vascular endothelial cells (VECs) around inflammatory foci and facilitates inflammation, demyelination, and paralysis. Therefore, we investigated the role of CD31-positive VECs in mPGES-1-mediated EAE aggravation using immunohistochemical analysis and imaging of wild-type (wt) and mPGES-1-deficient (mPGES-1^-/-) mice. We demonstrated that EAE induction facilitated vascularity in inflammatory lesions in the spinal cord, and this was significantly higher in wt mice than in mPGES-1^-/- mice. In addition, endothelial interleukin-1β (IL-1β) production was significantly higher in wt mice than in mPGES-1^-/- mice. Moreover, endothelial PGE₂ receptors (E-prostanoid (EP) receptors EP1⁻4) were expressed after EAE induction, and IL-1β was induced in EP receptor-positive VECs. Furthermore, IL-1 receptor 1 expression on VECs was increased upon EAE induction. Thus, increased vascularity is one mechanism involved in EAE aggravation induced by mPGES-1. Furthermore, mPGES-1 facilitated the autocrine function of VECs upon EP receptor induction and IL-1β production, modulating mPGES-1 induction in EAE.

Long non-coding RNA cox-2 prevents immune evasion and metastasis of hepatocellular carcinoma by altering M1/M2 macrophage polarization

Macrophages have been shown to demonstrate a high level of plasticity, with the ability to undergo dynamic transition between M1 and M2 polarized phenotypes. We investigate long non-coding RNA (lncRNA) cox-2 in macrophage polarization and the regulatory mechanism functions in hepatocellular carcinoma (HCC). Lipopolysaccharide (LPS) was used to induce RAW264.7 macrophages into M1 type, and IL-4 was to induce RAW264.7 macrophages into M2 type. We selected mouse hepatic cell line Hepal-6 and hepatoma cell line HepG2 for co-incubation with M1 or M2 macrophages. Quantitative real-time PCR was used to detect the expressions of lncRNA cox-2 and mRNAs. ELISA was conducted for testing IL-12 and IL-10 expressions; Western blotting for epithelial mesenchymal transition related factors (E-cadherin and Vimentin). An MTT, colony formation assay, flow cytometry, transwell assay, and stretch test were conducted to test cell abilities. The M1 macrophages had higher lncRNA cox-2 expression than that in the non-polarized macrophages and M2 macrophages. The lncRNA cox-2 siRNA decreased the expression levels of IL-12, iNOS, and TNF-α in M1 macrophages, increased the expression levels of IL-10, Arg-1, and Fizz-1 in M2 macrophages (all P < 0.05). The lncRNA cox-2 siRNA reduces the ability of M1 macrophages to inhibit HCC cell proliferation, invasion, migration, EMT, angiogenesis and facilitate apoptosis while strengthening the ability of M2 macrophages to promote proliferation HCC cell growth and inhibit apoptosis. These findings indicate that lncRNA cox-2 inhibits HCC immune evasion and tumor growth by inhibiting the polarization of M2 macrophages.

Opportunities for Translation from the Bench: Therapeutic Intervention of the JAK/STAT Pathway in Neuroinflammatory Diseases

Pathogenic CD4+ T cells and myeloid cells play critical roles in the pathogenesis of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), an animal model of MS. These immune cells secrete aberrantly high levels of pro-inflammatory cytokines that pathogenically bridge the innate and adaptive immune systems and damage neurons and oligodendrocytes. These cytokines include interleukin-2 (IL-2), IL-6, IL-12, IL-21, IL-23, granulocyte macrophage-colony stimulating factor (GM-CSF), and interferon-γ (IFN-γ). It is, therefore, not surprising that both the dysregulated expression of these cytokines and the subsequent activation of their downstream signaling cascades is a common feature in MS/EAE. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway is utilized by numerous cytokines for signal transduction and is essential for the development and regulation of immune responses. Unbridled activation of the JAK/STAT pathway by pro-inflammatory cytokines has been demonstrated to be critically involved in the pathogenesis of MS/EAE. In this review, we discuss recent advancements in our understanding of the involvement of the JAK/STAT signaling pathway in the pathogenesis of MS/EAE, with a particular focus on therapeutic approaches to target the JAK/STAT pathway.

Microsomal Prostaglandin E Synthase-1 Facilitates an Intercellular Interaction between CD4⁺ T Cells through IL-1β Autocrine Function in Experimental Autoimmune Encephalomyelitis

Microsomal prostaglandin synthetase-1 (mPGES-1) is an inducible terminal enzyme that produces prostaglandin E₂ (PGE₂). In our previous study, we investigated the role of mPGES-1 in the inflammation and demyelination observed in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, using mPGES-1-deficient (mPGES-1^−/−) and wild-type (wt) mice. We found that mPGES-1 facilitated inflammation, demyelination, and paralysis and was induced in vascular endothelial cells and macrophages and microglia around inflammatory foci. Here, we investigated the role of interleukin-1β (IL-1β) in the intercellular mechanism stimulated by mPGES-1 in EAE spinal cords in the presence of inflammation. We found that the area invaded by CD4-positive (CD4⁺) T cells was extensive, and that PGE₂ receptors EP1–4 were more induced in activated CD4⁺ T cells of wt mice than in those of mPGES-1^−/− mice. Moreover, IL-1β and IL-1 receptor 1 (IL-1r1) were produced by 65% and 48% of CD4⁺ T cells in wt mice and by 44% and 27% of CD4⁺ T cells in mPGES-1^−/− mice. Furthermore, interleukin-17 (IL-17) was released from the activated CD4⁺ T cells. Therefore, mPGES-1 stimulates an intercellular interaction between CD4⁺ T cells by upregulating the autocrine function of IL-1β in activated CD4⁺ T cells, which release IL-17 to facilitate axonal and myelin damage in EAE mice.

Anemoside A3 ameliorates experimental autoimmune encephalomyelitis by modulating T helper 17 cell response

Anemoside A₃ (AA3) is a natural triterpenoid glycoside isolated from the root of Pulsatilla chinensis (Bunge) Regel. We previously showed that AA3 exhibits cognitive-enhancing and neuroprotective properties. In the present study, we demonstrated that AA3 modulates inflammatory responses by regulating prostaglandin E receptor 4 signaling. Because prostaglandin E receptor 4 is involved in the pathophysiology of experimental autoimmune encephalomyelitis (EAE), an animal model of human multiple sclerosis (MS), we assessed the beneficial effect of AA3 in EAE mice. AA3 treatment significantly reduced clinical severity and inflammatory infiltrates in the spinal cord of EAE mice. In vitro studies revealed that AA3 inhibited the T cell response toward the encephalitogenic epitope of myelin oligodendrocyte glycoprotein (MOG). AA3 significantly downregulated the expressions of certain Th1 and Th17 cytokines in activated T cells re-stimulated by MOG. Moreover, AA3 inhibited the activation of STAT4 and STAT3, which are the transcription factors pivotal for Th1 and Th17 lineage differentiation, respectively, in activated T cells. Pharmacological analysis further suggested that AA3 reduced Th17 cell differentiation and expansion. In conclusion, AA3 exerts an immunomodulatory effect in EAE, demonstrating its potential as a therapeutic agent for MS in humans.

The natural dual cyclooxygenase and 5-lipoxygenase inhibitor flavocoxid is protective in EAE through effects on Th1/Th17 differentiation and macrophage/microglia activation

Prostaglandins and leukotrienes, bioactive mediators generated by cyclooxygenases (COX) and 5-lipoxygenase (5-LO) from arachidonic acid, play an essential role in neuroinflammation. High levels of LTB4 and PGE2 and increased expression of COX and 5-LO, as well as high expression of PGE2 receptors were reported in multiple sclerosis (MS) patients and in experimental autoimmune encephalomyelitis (EAE). Prostaglandins and leukotrienes have an interdependent and compensatory role in EAE, which led to the concept of therapy using dual COX/5-LO inhibitors. The plant derived flavocoxid, a dual COX/5-LO inhibitor with anti-inflammatory and antioxidant properties, manufactured as a prescription pharmaconutrient, was reported to be neuroprotective in models of transient ischemic stroke and brain injury. The present study is the first report on prophylactic and therapeutic effects of flavocoxid in EAE. The beneficial effects correlate with reduced expression of proinflammatory cytokines and of COX2 and 5-LO in spinal cords and spleens of EAE mice. The protective mechanisms include: 1. reduction in expression of MHCII/costimulatory molecules and production of proinflammatory cytokines; 2. promotion of the M2 phenotype including IL-10 expression and release by macrophages and microglia; 3. inhibition of Th1 and Th17 differentiation through direct effects on T cells. The direct inhibitory effect on Th1/Th17 differentiation, and promoting the development of M2 macrophages and microglia, represent novel mechanisms for the flavocoxid anti-inflammatory activity. As a dual COX/5-LO inhibitor with antioxidant properties, flavocoxid might be useful as a potential therapeutic medical food agent in MS patients.

Translational utility of experimental autoimmune encephalomyelitis: recent developments

Multiple sclerosis (MS) is a complex autoimmune condition with firmly established genetic and environmental components. Genome-wide association studies (GWAS) have revealed a large number of genetic polymorphisms in the vicinity of, and within, genes that associate to disease. However, the significance of these single-nucleotide polymorphisms in disease and possible mechanisms of action remain, with a few exceptions, to be established. While the animal model for MS, experimental autoimmune encephalomyelitis (EAE), has been instrumental in understanding immunity in general and mechanisms of MS disease in particular, much of the translational information gathered from the model in terms of treatment development (glatiramer acetate and natalizumab) has been extensively summarized. In this review, we would thus like to cover the work done in EAE from a GWAS perspective, highlighting the research that has addressed the role of different GWAS genes and their pathways in EAE pathogenesis. Understanding the contribution of these pathways to disease might allow for the stratification of disease subphenotypes in patients and in turn open the possibility for new and individualized treatment approaches in the future.

The role of the prostaglandin E2 receptors in vulnerability of oligodendrocyte precursor cells to death

Background

Activity of cyclooxygenase 2 (COX-2) in mouse oligodendrocyte precursor cells (OPCs) modulates vulnerability to excitotoxic challenge. The mechanism by which COX-2 renders OPCs more sensitive to excitotoxicity is not known. In the present study, we examined the hypothesis that OPC excitotoxic death is augmented by COX-2-generated prostaglandin E2 (PGE₂) acting on specific prostanoid receptors which could contribute to OPC death.

Methods

Dispersed OPC cultures prepared from mice brains were examined for expression of PGE₂ receptors and the ability to generate PGE₂ following activation of glutamate receptors with kainic acid (KA). OPC death in cultures was induced by either KA, 3′-O-(Benzoyl) benzoyl ATP (BzATP) (which stimulates the purinergic receptor P2X7), or TNFα, and the effects of EP3 receptor agonists and antagonists on OPC viability were examined.

Results

Stimulation of OPC cultures with KA resulted in nearly a twofold increase in PGE₂. OPCs expressed all four PGE receptors (EP1–EP4) as indicated by immunofluorescence and Western blot analyses; however, EP3 was the most abundantly expressed. The EP3 receptor was identified as a candidate contributing to OPC excitotoxic death based on pharmacological evidence. Treatment of OPCs with an EP1/EP3 agonist 17 phenyl-trinor PGE₂ reversed protection from a COX-2 inhibitor while inhibition of EP3 receptor protected OPCs from excitotoxicity. Inhibition with an EP1 antagonist had no effect on OPC excitotoxic death. Moreover, inhibition of EP3 was protective against toxic stimulation with KA, BzATP, or TNFα.

Conclusion

Therefore, inhibitors of the EP3 receptor appear to enhance survival of OPCs following toxic challenge and may help facilitate remyelination.

Involvement of the janus kinase/signal transducer and activator of transcription signaling pathway in multiple sclerosis and the animal model of experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) and its animal model of experimental autoimmune encephalomyelitis (EAE) are characterized by focal inflammatory infiltrates into the central nervous system, demyelinating lesions, axonal damage, and abundant production of cytokines that activate immune cells and damage neurons and oligodendrocytes, including interleukin-12 (IL-12), IL-6, IL-17, IL-21, IL-23, granulocyte macrophage-colony stimulating factor, and interferon-gamma. The Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) signaling pathway mediates the biological activities of these cytokines and is essential for the development and regulation of immune responses. Dysregulation of the JAK/STAT pathway contributes to numerous autoimmune diseases, including MS/EAE. The JAK/STAT pathway is aberrantly activated in MS/EAE because of excessive production of cytokines, loss of expression of negative regulators such as suppressors of cytokine signaling proteins, and significant enrichment of genes encoding components of the JAK/STAT pathway, including STAT3. Specific JAK/STAT inhibitors have been used in numerous preclinical models of MS and demonstrate beneficial effects on the clinical course of disease and attenuation of innate and adaptive immune responses. In addition, other drugs such as statins, glatiramer acetate, laquinimod, and fumarates have beneficial effects that involve inhibition of the JAK/STAT pathway. We conclude by discussing the feasibility of the JAK/STAT pathway as a target for neuroinflammatory diseases.

IL-35 Is Involved in the Pathogenesis of Guillain-Barré Syndrome Through Its Influence on the Function of CD4+ T Cells

CD4+ T cells and many cytokines play critical roles in the pathogenesis of Guillain-Barré Syndrome (GBS), an immune-mediated inflammatory disease. However, the role of IL-35, a novel member of the IL-12 cytokine family, in this kind of disease has not yet been elucidated. In this study, we investigated the functional changes of CD4+ T cells from GBS patients with IL-35 treatment in vitro. This study involved 21 GBS patients and an equal number of healthy controls (HCs). The results indicated that the average concentration of IL-35 in the plasma of GBS patients was lower than that of healthy controls (HCs). Increased levels of STAT1, STAT3 and STAT4 proteins and T-bet, ROR γt, IFN-γ and IL-17A mRNA were observed in CD4+ T cells from GBS patients. In contrast, the levels of STAT5 and STAT6 proteins and GATA3, Foxp3, IL-4 and TGF-β1 mRNAs were decreased in GBS patients in comparison with those of HCs. In addition, treatment of CD4+ T cells from GBS patients with IL-35 upregulated IL-35, STAT5 and STAT6 protein and T-bet, GATA3, Foxp3, IFN-γ, IL-4, IL-17A and TGF-β1 mRNA while inhibited levels of STAT3 and STAT4 protein and RORγt and IL-17A mRNA. These results indicate that IL-35 might play a potential role in GBS pathogenesis. Further studies are required in order to evaluate its role in GBS.

Combination Treatment with Apricoxib and IL-27 Enhances Inhibition of Epithelial-Mesenchymal Transition in Human Lung Cancer Cells through a STAT1 Dominant Pathway

BACKGROUND

The cyclooxygenase 2 (COX-2) pathway has been implicated in the molecular pathogenesis of many malignancies, including lung cancer. Apricoxib, a selective COX-2 inhibitor, has been described to inhibit epithelial-mesenchymal transition (EMT) in human malignancies. The mechanism by which apricoxib may alter the tumor microenvironment by affecting EMT through other important signaling pathways is poorly defined. IL-27 has been shown to have anti-tumor activity and our recent study showed that IL-27 inhibited EMT through a STAT1 dominant pathway.

OBJECTIVE

The purpose of this study is to investigate the role of apricoxib combined with IL-27 in inhibiting lung carcinogenesis by modulation of EMT through STAT signaling.

METHODS AND RESULTS

Western blot analysis revealed that IL-27 stimulation of human non-small cell lung cancer (NSCLC) cell lines results in STAT1 and STAT3 activation, decreased Snail protein and mesenchymal markers (N-cadherin and vimentin) and a concomitant increase in expression of epithelial markers (E-cadherin, β-and γ-catenins), and inhibition of cell migration. The combination of apricoxib and IL-27 resulted in augmentation of STAT1 activation. However, IL-27 mediated STAT3 activation was decreased by the addition of apricoxib. STAT1 siRNA was used to determine the involvement of STAT1 pathway in the enhanced inhibition of EMT and cell migration by the combined IL-27 and apricoxib treatment. Pretreatment of cells with STAT1 siRNA inhibited the effect of combined IL-27 and apricoxib in the activation of STAT1 and STAT3. In addition, the augmented expression of epithelial markers, decreased expression mesenchymal markers, and inhibited cell migration by the combination treatment were also inhibited by STAT1 siRNA, suggesting that the STAT1 pathway is important in the enhanced effect from the combination treatment.

CONCLUSION

Combined apricoxib and IL-27 has an enhanced effect in inhibition of epithelial-mesenchymal transition and cell migration in human lung cancer cells through a STAT1 dominant pathway.

MicroRNA-containing T-regulatory-cell-derived exosomes suppress pathogenic T helper 1 cells

Foxp3(+) T regulatory (Treg) cells prevent inflammatory disease but the mechanistic basis of suppression is not understood completely. Gene silencing by RNA interference can act in a cell-autonomous and non-cell-autonomous manner, providing mechanisms of intercellular regulation. Here, we demonstrate that non-cell-autonomous gene silencing, mediated by miRNA-containing exosomes, is a mechanism employed by Treg cells to suppress T-cell-mediated disease. Treg cells transferred microRNAs (miRNA) to various immune cells, including T helper 1 (Th1) cells, suppressing Th1 cell proliferation and cytokine secretion. Use of Dicer-deficient or Rab27a and Rab27b double-deficient Treg cells to disrupt miRNA biogenesis or the exosomal pathway, respectively, established a requirement for miRNAs and exosomes for Treg-cell-mediated suppression. Transcriptional analysis and miRNA inhibitor studies showed that exosome-mediated transfer of Let-7d from Treg cell to Th1 cells contributed to suppression and prevention of systemic disease. These studies reveal a mechanism of Treg-cell-mediated suppression mediated by miRNA-containing exosomes.

Therapeutic targeting of STAT pathways in CNS autoimmune diseases

Signal transducers and activators of transcription (STATs) transduce extracellular signals that regulate the initiation, duration and intensity of immune responses. However, unbridled activation of STATs by pro-inflammatory cytokines or growth factors contributes to pathogenic autoimmunity. In this review, we briefly discuss STAT pathways that promote the development and expansion of T cells that mediate two CNS inflammatory diseases, multiple sclerosis (MS) and uveitis. Particular focus is on animal models of MS and uveitis and new approaches to the treatment of CNS autoimmune diseases based on therapeutic targeting of Th17 cells and STAT pathways.

Alterations of brain eicosanoid synthetic pathway in multiple sclerosis and in animal models of demyelination: role of cyclooxygenase-2

Inflammation is a physiological response to exogenous and endogenous stimuli and, together with demyelination and immune system activation, is one of the key features of multiple sclerosis (MS). Arachidonic acid (AA) metabolism by cyclooxygenase (COX) and lipoxygenase (LO) enzymes leads to the production of proinflammatory eicosanoids, and stimulates cytokine production and activation of microglia and astrocytes, thereby contributing to MS pathology. Current therapies target the immune system but do not specifically target AA-related inflammatory pathway. Corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs) are frequently associated with immunomodulatory therapies to treat flu-like adverse effects. Few clinical and mounting preclinical data in MS show that AA metabolism contributes to immune system activation, demyelination and motor disabilities, and administration of NSAIDs reduces these symptoms. The beneficial effect of NSAIDs seems to be a prerogative of COX-2 selective inhibitors and suggests that NSAIDs selective for COX-2 may be more effective than mixed COX-1/2 inhibitors.

A 63 year old woman with white matter lesions and pachymeningeal inflammation

We describe the case of a 63-year-old woman with CNS Rosai-Dorfman disease, presenting with diffuse dural infiltration, mimicking idiopathic hypertrophic pachymeningitis, and right vertebral artery dissection. Her symptoms included a progressive 11-month history of vertigo, gait ataxia, and right thalamic stroke. A diagnosis of CNS Rosai-Dorfman disease was made following open dural biopsy, and later confirmed on autopsy studies. The autopsy demonstrated widespread dural infiltration by inflammatory cells, principally large histiocytes, many of which exhibited emperipolesis, a characteristic finding in Rosai-Dorfman disease. A second pathological finding on autopsy was the presence of multiple demyelinating plaques (with preservation of axons), located in the corpus callosum, periventricular white matter, and multiple brainstem segments. These were consistent with a diagnosis of multiple sclerosis. This case description serves to remind clinicians that CNS Rosai-Dorfman disease—although uncommon—may present as a focal, dural-based, hemispheric mass lesion, or as diffuse pachymeningeal inflammation. Our case was also unusual due to the co-existence of CNS Rosai-Dorfman disease, multiple sclerosis, and polycythemia vera (all rare diseases) in a single patient. Although the overlap of disorders may have been co-incidental, one could raise the question whether all three disorders were triggered by the same underlying dysimmune state.

Teriflunomide for oral therapy in multiple sclerosis

Teriflunomide, the active metabolite of an approved antirheumatic drug, is an emerging oral therapy for multiple sclerosis (MS). Next to the inhibition of pyrimidine biosynthesis and proliferation of activated lymphocytes, it seems to have multiple anti-inflammatory and immunomodulating effects. Phase II and III clinical trials in relapsing MS demonstrated favorable safety and tolerability of the drug, as well as clinical efficacy, with a significant reduction of relapse rate, comparable with those of the available injectable immunomodulatory agents. While multiple other studies with teriflunomide are currently ongoing, its exact place in future treatment algorithms for MS is difficult to predict. It may be a good alternative for patients wishing to have an oral treatment with relatively large data regarding long-term safety.

Decreased signal transducers and activators of transcription (STAT) protein expression in lymphatic organs during EAE development in mice

Experimental autoimmune encephalomyelitis (EAE) is mediated by myelin-specific CD4+ T cells secreting Th1 and/or Th17 cytokines. Signal transducer and activator of transcription (STAT) family proteins have essential roles in transmitting Th1 and/or Th17 cytokine-mediated signals. However, most studies demonstrating the importance of the STAT signaling system in EAE have focused on distinct members of this family, often looking at their role specifically in the central nervous system, or in vitro. There is limited information available regarding the temporal and spatial expression patterns of each STAT protein and interplay between STAT proteins over the course of EAE development in critical lymphatic organs in vivo. In the present study, we demonstrate dramatic and progressive decrease of all six STAT family members (STAT1, STAT2, STAT3, STAT4, STAT5, STAT6) in the spleen and lymph nodes through the course of EAE development in SJL/J mice, in contrast with almost steady expression of thymic STAT proteins. Decreased splenic and lymphatic STAT expression was accompanied by significant enlargement of the spleen and lymph nodes, and histological proliferation of T cell areas with remodeling of the splenic microstructure in EAE mice. All STAT family members except STAT2 were mainly confined in T cell areas in spleen, whereas they were distributed in a protein specific manner in thymus. We present here a comprehensive analysis of all six members of the STAT family in spleen, lymph nodes and thymus through the development phase of EAE. Results suggest that EAE induced inflammatory T cells may develop distinct biological features different from normal splenic T cells due to altered STAT signaling.

Aurintricarboxylic acid ameliorates experimental autoimmune encephalomyelitis by blocking chemokine-mediated pathogenic cell migration and infiltration

Multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), are autoimmune diseases characterized by the immune-mediated demyelination and neurodegeneration of the CNS. Overactivation of CD4(+) T cells, especially the Th1 and Th17 subpopulations, is thought to be the direct cause of this disease. Aurintricarboxylic acid (ATA), an inhibitor of protein-nucleic acid interaction, has been reported to block with the JAK/STAT signaling pathway that is critical for Th cell differentiation. In this study, we discovered that ATA treatment significantly reduces the clinical score of EAE, but it does not directly inhibit the differentiation of Th1 and Th17 cells in vitro. ATA was found to block the chemotaxis and accumulation of dendritic cells in the spleen of EAE mice before the onset of the disease and to reduce the percentage of Th1 and Th17 cells in the spleen. Further study revealed that ATA also blocks the infiltration of pathogenic T cells into the CNS and blocks the onset of passive EAE. ATA was found to inhibit the functions of many chemokine receptors. By blocking chemokine-mediated migration of dendritic cells and pathogenic T cells, ATA alleviates the pathogenesis of EAE and might be used to treat autoimmune diseases, including multiple sclerosis.

Microsomal prostaglandin E synthase-1 aggravates inflammation and demyelination in a mouse model of multiple sclerosis

Microsomal prostaglandin synthetase-1 (mPGES-1) is an inducible terminal enzyme required for prostaglandin E(2) (PGE(2)) biosynthesis. In this study, we examined the role of mPGES-1 in the inflammation and demyelination observed in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). We induced EAE with myelin oligodendrocyte glycoprotein(35-55) peptide in mPGES-1-deficient (mPGES-1(-/-)) and wild-type (WT) mice. First, we examined the histopathology in the early and late phases of EAE progression. Next, we measured the concentration of PGE(2) in the spinal cord and investigated the expression of mPGES-1 using immunohistochemistry. In addition, we examined the progression of the severity of EAE using an EAE score to investigate a correlation between pathological features and paralysis. In this paper, we demonstrate that WT mice showed extensive inflammation and demyelination, whereas mPGES-1(-/-) mice exhibited significantly smaller and more localized changes in the perivascular area. The mPGES-1 protein was induced in vascular endothelial cells and microglia around inflammatory foci, and PGE(2) production was increased in WT mice but not mPGES-1(-/-) mice. Furthermore, mPGES-1(-/-) mice showed a significant reduction in the maximum EAE score and improved locomotor activity. These results suggest that central PGE(2) derived from non-neuronal mPGES-1 aggravates the disruption of the vessel structure, leading to the spread of inflammation and local demyelination in the spinal cord, which corresponds to the symptoms of EAE. The inhibition of mPGES-1 may be useful for the treatment of human MS.

Regulation of T helper cell subsets by cyclooxygenases and their metabolites

Cyclooxygenases and their metabolites are important regulators of inflammatory responses and play critical roles in regulating the differentiation of T helper cell subsets in inflammatory diseases. In this review, we highlight new information on regulation of T helper cell subsets by cyclooxygenases and their metabolites. Prostanoids influence cytokine production by both antigen presenting cells and T cells to regulate the differentiation of naïve CD4(+) T cells to Th1, Th2 and Th17 cell phenotypes. Cyclooxygenases and PGE2 generally exacerbate Th2 and Th17 phenotypes, while suppressing Th1 differentiation. Thus, cycloxygenases may play a critical role in diseases that involve immune cell dysfunction. Targeting of cyclooxygenases and their eicosanoid products may represent a new approach for treatment of inflammatory diseases, tumors and autoimmune disorders.

Cannabinoids, multiple sclerosis and neuroprotection

The cannabinoid signaling system participates in the control of cell homeostasis in the CNS, which explains why, in different neurodegenerative diseases including multiple sclerosis (MS), alterations in this system have been found to serve both as a pathogenic factor (malfunctioning of this system has been found at early phases of these diseases) and as a therapeutic target (the management of this system has beneficial effects). MS is an autoimmune disease that affects the CNS and it is characterized by inflammation, demyelination, remyelination, gliosis and axonal damage. Although it has been considered mainly as an inflammatory disorder, recent studies have recognized the importance of axonal loss both in the progression of the disorder and in the appearance of neurological disability, even in early stages of the disease. In recent years, several laboratories have addressed the therapeutic potential of cannabinoids in MS, given the experience reported by some MS patients who self-medicated with marijuana. Most of these studies focused on the alleviation of symptoms (spasticity, tremor, anxiety and pain) or on the inflammatory component of the disease. However, recent data also revealed the important neuroprotective action that could be exerted by cannabinoids in this disorder. The present review will be precisely centered on this neuroprotective potential, which is based mainly on antioxidant, anti-inflammatory and anti-excitotoxic properties, exerted through the activation of CB1 or CB2 receptors or other unknown mechanisms.

C6-ceramide enhances Interleukin-12-mediated T helper type 1 cell responses through a cyclooxygenase-2-dependent pathway

Ceramides, lipid molecules located predominantly within the plasma membrane of a cell, can function as second messengers, and have been known to carry out a number of cellular functions. T helper type 1 (Th1) immune responses are known to be involved in the cellular immunity, which is crucial in the cancer and allergy immunotherapy. This study was designed to evaluate the effects of ceramides on T helper cell responses and their underlying mechanisms. We demonstrated that a cell-permeable C6-ceramide (C6) together with IL-12 enhanced Th1 cell differentiation, whereas C6 alone had no effects, as demonstrated by the increased populations of IFN-γ expressing CD4(+) T cells and the up-regulation of IFN-γ production from CD4(+) T cells. In contrast, C2-ceramide and long chain ceramides (C16 and C24) did not affect the Th1 responses. C6 treatment was shown to increase the expression of T-bet, a master transcription factor of Th1 responses, in a dose-dependent fashion. Furthermore, C6 increased the expression of cyclooxygenase-2 (COX-2) in CD4(+) T cells. The C6-mediated increase of IFN-γ production and IFN-γ expressing CD4(+) T cell populations were significantly suppressed by a COX-2 specific inhibitor (NS-398) in a dose-dependent manner. T-bet expression was also decreased by NS-398 treatment, thereby indicating that C6 ceramide enhances Th1 responses via a COX-2 dependent pathway. This result demonstrates that C6 may be utilized in therapies for the treatment of immune diseases such cancer and allergy by enhancing the Th1 activity.

The cyclooxygenase-2 pathway via the PGE₂ EP2 receptor contributes to oligodendrocytes apoptosis in cuprizone-induced demyelination

Cyclooxygenases (COX)-1 and -2 are key enzymes required for the conversion of arachidonic acid to eicosanoids, potent mediators of inflammation. In patients with multiple sclerosis, COX-2 derived prostaglandins (PGs) are elevated in the CSF and COX-2 is up-regulated in demyelinating plaques. However, it is not known whether COX-2 activity contributes to oligodendrocyte death. In cuprizone-induced demyelination, oligodendrocyte apoptosis and a concomitant increase in the gene expression of COX-2 and PGE₂-EP2 receptor precede histological demyelination. COX-2 and EP2 receptor were expressed by oligodendrocytes, suggesting a causative role for the COX-2/EP2 pathway in the initiation of oligodendrocyte death and demyelination. COX-2 gene deletion, chronic treatment with the COX-2 selective inhibitor celecoxib, or with the EP2 receptor antagonist AH6809 reduced cuprizone-induced oligodendrocyte apoptosis, the degree of demyelination and motor dysfunction. These data indicate that the PGE₂ EP2 receptor contributes to oligodendrocyte apoptosis and open possible new therapeutic approaches for multiple sclerosis.

Cytosolic phospholipase A2α blockade abrogates disease during the tissue-damage effector phase of experimental autoimmune encephalomyelitis by its action on APCs

Cytosolic phospholipase A(2)α (cPLA(2)α) is the rate-limiting enzyme for release of arachidonic acid, which is converted primarily to PGs via the cyclooxygenase 1 and 2 pathways and to leukotrienes via the 5-lipoxygenase pathway. We used adoptive transfer and relapsing-remitting forms of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, in two different strains of mice (SJL or C57BL/6) to demonstrate that blockade of cPLA(2)α with a highly specific small-molecule inhibitor during the tissue-damage effector phase abrogates the clinical manifestation of disease. Using the adoptive transfer model in SJL mice, we demonstrated that the blockade of cPLA(2)α during the effector phase of disease was more efficacious in ameliorating the disease pathogenesis than the blockade of each of the downstream enzymes, cyclooxygenase-1/2 and 5-lipooxygenase. Similarly, blockade of cPLA(2)α was highly efficacious in ameliorating disease pathogenesis during the effector phase of EAE in the adoptive transfer model of EAE in C57BL/6 mice. Investigation of the mechanism of action indicates that cPLA(2)α inhibitors act on APCs to diminish their ability to induce Ag-specific effector T cell proliferation and proinflammatory cytokine production. Furthermore, cPLA(2)α inhibitors may prevent activation of CNS-resident microglia and may increase oligodendrocyte survival. Finally, in a relapsing-remitting model of EAE in SJL mice, therapeutic administration of a cPLA(2)α inhibitor, starting from the peak of disease or during remission, completely protected the mice from subsequent relapses.

Arachidonyl trifluoromethyl ketone ameliorates experimental autoimmune encephalomyelitis via blocking peroxynitrite formation in mouse spinal cord white matter

Inhibition of phospholipase A(2) (PLA(2)) has recently been found to attenuate the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a commonly used animal model of multiple sclerosis (MS). However, the protective mechanisms that underlie PLA(2) inhibition are still not well understood. In this study, we found that cytosolic PLA(2) (cPLA(2)) was highly expressed in infiltrating lymphocytes and macrophages/microglia in mouse spinal cord white matter. Although cPLA(2) is also expressed in spinal cord neurons and oligodendrocytes, there were no differences observed in these cell types between EAE and control animals. Arachidonyl trifluoromethyl ketone (AACOCF3), a cPLA(2) inhibitor, significantly reduced the clinical symptoms and inhibited the body weight loss typically found in EAE mice. AACOCF3 also attenuated the loss of mature, myelin producing, oligodendrocytes, and axonal damage in the spinal cord white matter. Nitrotyrosine immunoreactivity, an indicator of peroxynitrite formation, was dramatically increased in EAE mice and attenuated by treatment with AACOCF3. These protective effects were not evident when AA861, an inhibitor of lipoxygenase, was used. In primary cultures of microglia, lipopolysaccharide (LPS) induced an upregulation of cPLA(2), inducible nitric oxide synthase (iNOS) and components of the NADPH oxidase complex, p47phox and p67phox. AACOCF3 significantly attenuated iNOS induction, nitric oxide production and the generation of reactive oxygen species in reactive microglia. Similar to the decomposition catalyst of peroxynitrite, AACOCF3 also blocked oligodendrocyte toxicity induced by reactive microglia. These results suggest that AACOCF3 may prevent oligodendrocyte loss in EAE by attenuating peroxynitrite formation in the spinal cord white matter.

Cyclooxygenase expression and prostaglandin levels in central nervous system tissues during the course of chronic relapsing experimental autoimmune encephalomyelitis (EAE)

OBJECTIVE

Multiple sclerosis (MS) and its animal counterpart experimental autoimmune encephalomyelitis (EAE) have a major inflammatory component that drives and orchestrates both diseases. One particular group of mediators are the prostaglandins (PGs), which we have previously shown, through quantitation and pharmacological intervention, to be closely involved in the pathology of MS and EAE. The aim of the current study was to determine the expression of the PG-generating cyclooxygenase (COX) enzymes and the profile of PGE(2) and PGD(2), in selected central nervous system (CNS) tissues, with the development of the chronic relapsing (CR) form of EAE. In particular, the work investigates the possible relationship between the expression of COX isoenzymes and PG levels during the neurological phases of CR EAE.

METHODS

CR EAE was induced in Biozzi mice with inoculum containing lyophilised, syngeneic spinal cord emulsified in complete Freund's adjuvant. The cerebral cortex, cerebellum and spinal cord were dissected from mice during the acute, remission and relapse stages of disease with a minimum of five animals per treatment. The expression of COX-1, COX-1b variant and COX-2, in pooled samples, was determined by Western blotting. PGE(2) and PGD(2) levels in extracted samples were measured using commercial enzyme immunoassay kits.

RESULTS

COX-2 expression in spinal cords during acute disease remained unaltered and was in contrast to an enhancement of the enzyme, together with COX-1 and COX-1b, in all other sampled areas. PGE(2) and PGD(2) levels remained unchanged during the acute phase and the subsequent remission of symptoms. COX-1 and COX-1b expression was elevated in tissues during the relapse stage of CR EAE and concentrations of the prostanoids were markedly increased.

CONCLUSIONS

The study examines the implications of COX isoenzyme expression over the course of CR EAE and discusses the reported relationship between PGE(2) and PGD(2) in the instigation and resolution of CNS inflammation. Consideration is also given to the treatment of CR EAE and suggests that drugs designed to limit the inflammatory effects of the PGs should be administered prior to or during the relapse phase of the disease.

Cyclooxygenase-2 expression in oligodendrocytes increases sensitivity to excitotoxic death

BACKGROUND

We previously found that cyclooxygenase 2 (COX-2) was expressed in dying oligodendrocytes at the onset of demyelination in the Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD) model of multiple sclerosis (MS) (Carlson et al. J.Neuroimmunology 2006, 149:40). This suggests that COX-2 may contribute to death of oligodendrocytes.

OBJECTIVE

The goal of this study was to examine whether COX-2 contributes to excitotoxic death of oligodendrocytes and potentially contributes to demyelination.

METHODS

The potential link between COX-2 and oligodendrocyte death was approached using histopathology of MS lesions to examine whether COX-2 was expressed in dying oligodendrocytes. COX-2 inhibitors were examined for their ability to limit demyelination in the TMEV-IDD model of MS and to limit excitotoxic death of oligodendrocytes in vitro. Genetic manipulation of COX-2 expression was used to determine whether COX-2 contributes to excitotoxic death of oligodendrocytes. A transgenic mouse line was generated that overexpressed COX-2 in oligodendrocytes. Oligodendrocyte cultures derived from these transgenic mice were used to examine whether increased expression of COX-2 enhanced the vulnerability of oligodendrocytes to excitotoxic death. Oligodendrocytes derived from COX-2 knockout mice were evaluated to determine if decreased COX-2 expression promotes a greater resistance to excitotoxic death.

RESULTS

COX-2 was expressed in dying oligodendrocytes in MS lesions. COX-2 inhibitors limited demyelination in the TMEV-IDD model of MS and protected oligodendrocytes against excitotoxic death in vitro. COX-2 expression was increased in wild-type oligodendrocytes following treatment with Kainic acid (KA). Overexpression of COX-2 in oligodendrocytes increased the sensitivity of oligodendrocytes to KA-induced excitotoxic death eight-fold compared to wild-type. Conversely, oligodendrocytes prepared from COX-2 knockout mice showed a significant decrease in sensitivity to KA induced death.

CONCLUSIONS

COX-2 expression was associated with dying oligodendrocytes in MS lesions and appeared to increase excitotoxic death of oligodendrocytes in culture. An understanding of how COX-2 expression influences oligodendrocyte death leading to demyelination may have important ramifications for future treatments for MS.

Chronic inhibition of cyclooxygenase-2 attenuates antibody responses against vaccinia infection

Generation of optimal humoral immunity to vaccination is essential to protect against devastating infectious agents such as the variola virus that causes smallpox. Vaccinia virus (VV), employed as a vaccine against smallpox, provides an important model of infection. Herein, we evaluated the importance cyclooxygenase-2 (Cox-2) in immunity to VV using Cox-2 deficient mice and Cox-2 selective inhibitory drugs. The effects of Cox-2 inhibition on antibody responses to live viruses such as vaccinia have not been previously described. Here, we used VV infection in Cox-2 deficient mice and in mice chronically treated with Cox-2 selective inhibitors and show that the frequency of VV-specific B cells was reduced, as well as the production of neutralizing IgG. VV titers were approximately 70 times higher in mice treated with a Cox-2 selective inhibitor. Interestingly, Cox-2 inhibition also reduced the frequency of IFN-gamma producing CD4(+) T helper cells, important for class switching. The significance of these results is that the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs), and other drugs that inhibit Cox-2 activity or expression, blunt the ability of B cells to produce anti-viral antibodies, thereby making vaccines less effective and possibly increasing susceptibility to viral infection. These new findings support an essential role for Cox-2 in regulating humoral immunity.

The antidepressant venlafaxine ameliorates murine experimental autoimmune encephalomyelitis by suppression of pro-inflammatory cytokines

Antidepressants are known to impact on the immune system. In this study, we examined the immunomodulatory properties of venlafaxine, a selective serotonin/norepinephrine reuptake inhibitor (SNRI), in murine experimental autoimmune encephalomyelitis (EAE), a T-cell-mediated CNS demyelinating disease model of multiple sclerosis. EAE was induced in SJL/J mice by adoptive transfer of myelin-specific T cells. Mice received different doses of venlafaxine before induction and after onset of disease. Sustained daily oral treatment with 6, 20 and 60 mg/kg significantly ameliorated the clinical symptoms of the disease compared to vehicle during both preventive and therapeutic intervention. Venlafaxine suppressed the generation of pro-inflammatory cytokines IL-12 p40, TNF-alpha and IFN-gamma in encephalitogenic T-cell clones, splenocytes and peritoneal macrophages in vitro. It also diminished mRNA expression of a number of inflammatory genes in the inflamed CNS tissue, among them CD3, CD8, Granzyme B, IL-12 p40, IFN-gamma, TNF-alpha and the chemokines Ccl2 and RANTES, whereas the expression of brain-derived neurotrophic factor was increased. These findings demonstrate the strong immunomodulatory property of the selective SNRI venlafaxine. Further studies are warranted to clarify whether venlafaxine may exert similar effects in humans.

Prostaglandin E2 is a major soluble factor produced by stromal cells for preventing inflammatory cytokine production from dendritic cells

Dendritic cells (DCs) are specialized antigen-presenting cells that play pivotal roles in initiating immune responses. However, DC maturation is usually strongly restricted by the stromal microenvironment, especially in non-lymphoid tissues, such as skin and mucosa. Although suppression of DC maturation by stromal cells has been well documented, the molecular basis of this suppression has not been established. In this study, we examined the role of fibroblasts for DC maturation in vitro. The mouse embryonic fibroblasts (MEFs) strongly suppressed LPS-induced DC maturation. Although suppression of class II MHC and CD40 required DC-MEF contact, soluble factors in the culture supernatant of MEFs were sufficient for the suppression of IL-12 and tumor necrosis factor-alpha production. Using molecular-size selection and HPLC, we determined that prostaglandin E2 (PGE2) is a major soluble inhibitory factor secreted by MEFs. This was confirmed by the fact that cyclooxygenase inhibitors inhibited the production of the suppressive factor by MEFs. These results suggest that PGE2 is a major soluble factor produced by MEFs for the suppression of inflammatory cytokine production from DCs, while a contact mechanism between MEFs and DCs is required for the suppression to induce T cell-stimulating molecules.

15-deoxy-Delta(12,14)-prostaglandin J(2) and curcumin modulate the expression of toll-like receptors 4 and 9 in autoimmune T lymphocyte

INTRODUCTION

Experimental allergic encephalomyelitis (EAE) is a T cell-mediated autoimmune disease model for multiple sclerosis (MS). We have shown earlier that 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) and curcumin ameliorate EAE by modulating inflammatory signaling pathways in T lymphocytes. Toll-like receptors (TLRs), expressed primarily in innate immune cells, play critical roles in the pathogenesis of EAE. T lymphocytes also express TLRs and function as costimulatory receptors to upregulate proliferation and cytokine production in response to specific agonists.

DISCUSSION

In this study, we show that naïve CD4(+) and CD8(+) T cells express detectable levels of TLR4 and TLR9 and that increase after the induction of EAE in SJL/J and C57BL/6 mice by immunization with PLPp139-151 and MOGp35-55 antigen, respectively. It is interesting to note that in vivo treatment with 15d-PGJ2 or curcumin results in a significant decrease in TLR4 and TLR9 expression in CD4(+) and CD8(+) T cells in association with the amelioration of EAE.

CONCLUSION

Although the exact mechanisms are not known, the modulation of TLR expression in T lymphocytes by 15d-PGJ(2) and curcumin suggests new therapeutic targets in the treatment of T cell-mediated autoimmune diseases.

Cyclooxygenase-2 deficiency enhances Th2 immune responses and impairs neutrophil recruitment in hepatic ischemia/reperfusion injury

Cyclooxygenase-2 (COX-2) is a prostanoid-synthesizing enzyme that is critically implicated in a variety of pathophysiological processes. Using a COX-2-deficient mouse model, we present data that suggest that COX-2 has an active role in liver ischemia/reperfusion (I/R) injury. We demonstrate that COX-2-deficient mice had a significant reduction in liver damage after I/R insult. The inability of COX-2(-/-) to elaborate COX-2 products favored a Th2-type response in these mice. COX-2(-/-) livers after I/R injury showed significantly decreased levels of IL-2, as well as IL-12, a cytokine known to have a central role in Th1 effector cell differentiation. Moreover, such livers expressed enhanced levels of the anti-inflammatory cytokine IL-10, shifting the balance in favor of a Th2 response in COX-2-deficient mice. The lack of COX-2 expression resulted in decreased levels of CXCL2, a neutrophil-activating chemokine, reduced infiltration of MMP-9-positive neutrophils, and impaired late macrophage activation in livers after I/R injury. Additionally, Bcl-2 and Bcl-x(L) were normally expressed in COX-2(-/-) livers after injury, whereas respective wild-type controls were almost depleted of these two inhibitors of cell death. In contrast, caspase-3 activation and TUNEL-positive cells were depressed in COX-2(-/-) livers. Therefore, our data support the concept that COX-2 is involved in the pathogenic events occurring in liver I/R injury. The data also suggest that potential valuable therapeutic approaches in liver I/R injury may result from further studies aimed at identifying specific COX-2-derived prostanoid pathways.

Downregulation of CD4+CD25+ regulatory T cells may underlie enhanced Th1 immunity caused by immunization with activated autologous T cells

Regulatory T cells (Treg) play important roles in immune system homeostasis, and may also be involved in tumor immunotolerance by suppressing Th1 immune response which is involved in anti-tumor immunity. We have previously reported that immunization with attenuated activated autologous T cells leads to enhanced anti-tumor immunity and upregulated Th1 responses in vivo. However, the underlying molecular mechanisms are not well understood. Here we show that Treg function was significantly downregulated in mice that received immunization of attenuated activated autologous T cells. We found that Foxp3 expression decreased in CD4+CD25+ T cells from the immunized mice. Moreover, CD4+CD25+Foxp3+ Treg obtained from immunized mice exhibited diminished immunosuppression ability compared to those from naïve mice. Further analysis showed that the serum of immunized mice contains a high level of anti-CD25 antibody (about 30 ng/ml, p<0.01 vs controls). Consistent with a role of anti-CD25 response in the downregulation of Treg, adoptive transfer of serum from immunized mice to naïve mice led to a significant decrease in Treg population and function in recipient mice. The triggering of anti-CD25 response in immunized mice can be explained by the fact that CD25 was induced to a high level in the ConA activated autologous T cells used for immunization. Our results demonstrate for the first time that immunization with attenuated activated autologous T cells evokes anti-CD25 antibody production, which leads to impeded CD4+CD25+Foxp3+ Treg expansion and function in vivo. We suggest that dampened Treg function likely contributes to enhanced Th1 response in immunized mice and is at least part of the mechanism underlying the boosted anti-tumor immunity.

Curcumin and autoimmune disease

The immune system has evolved to protect the host from microbial infection; nevertheless, a breakdown in the immune system often results in infection, cancer, and autoimmune diseases. Multiple sclerosis, rheumatoid arthritis, type 1 diabetes, inflammatory bowel disease, myocarditis, thyroiditis, uveitis, systemic lupus erythromatosis, and myasthenia gravis are organ-specific autoimmune diseases that afflict more than 5% of the population worldwide. Although the etiology is not known and a cure is still wanting, the use of herbal and dietary supplements is on the rise in patients with autoimmune diseases, mainly because they are effective, inexpensive, and relatively safe. Curcumin is a polyphenolic compound isolated from the rhizome of the plant Curcuma longa that has traditionally been used for pain and wound-healing. Recent studies have shown that curcumin ameliorates multiple sclerosis, rheumatoid arthritis, psoriasis, and inflammatory bowel disease in human or animal models. Curcumin inhibits these autoimmune diseases by regulating inflammatory cytokines such as IL-1beta, IL-6, IL-12, TNF-alpha and IFN-gamma and associated JAK-STAT, AP-1, and NF-kappaB signaling pathways in immune cells. Although the beneficial effects of nutraceuticals are traditionally achieved through dietary consumption at low levels for long periods of time, the use of purified active compounds such as curcumin at higher doses for therapeutic purposes needs extreme caution. A precise understanding of effective dose, safe regiment, and mechanism of action is required for the use of curcumin in the treatment of human autoimmune diseases.

COX-2 inhibitors ameliorate experimental autoimmune encephalomyelitis through modulating IFN-γ and IL-10 production by inhibiting T-bet expression

The COX-2 inhibitors Rofecoxib (Rof) and Lumiracoxib (Lum) were evaluated in experimental autoimmune encephalomyelitis (EAE), the model of multiple sclerosis (MS). Administration of Rof and Lum significantly reduced the incidence and severity of EAE, which was associated with the inhibition of MOG 35-55 lymphocyte recall response, anti-MOG 35-55 T cell responses, and modulation of cytokines production. In vitro Rof and Lum inhibited primary T cells proliferation and modulated cytokine production. These findings highlight the fact that Rof and Lum likely prevents EAE by modulating Th1/Th2 response, and suggest its utility in the treatment of MS and other autoimmune diseases.

Differential gene expression patterns in cyclooxygenase-1 and cyclooxygenase-2 deficient mouse brain

Microarray analysis of gene expression in the cerebral cortex and hippocampus of mice deficient in cyclooxygenase-1 or cyclooxygenase-2 reveals that the two enzymes differentially modulate brain gene expression.

Background

Cyclooxygenase (COX)-1 and COX-2 produce prostanoids from arachidonic acid and are thought to have important yet distinct roles in normal brain function. Deletion of COX-1 or COX-2 results in profound differences both in brain levels of prostaglandin E₂ and in activation of the transcription factor nuclear factor-κB, suggesting that COX-1 and COX-2 play distinct roles in brain arachidonic acid metabolism and regulation of gene expression. To further elucidate the role of COX isoforms in the regulation of the brain transcriptome, microarray analysis of gene expression in the cerebral cortex and hippocampus of mice deficient in COX-1 (COX-1^-/-) or COX-2 (COX-2^-/-) was performed.

Results

A majority (>93%) of the differentially expressed genes in both the cortex and hippocampus were altered in one COX isoform knockout mouse but not the other. The major gene function affected in all genotype comparisons was 'transcriptional regulation'. Distinct biologic and metabolic pathways that were altered in COX^-/- mice included β oxidation, methionine metabolism, janus kinase signaling, and GABAergic neurotransmission.

Conclusion

Our findings suggest that COX-1 and COX-2 differentially modulate brain gene expression. Because certain anti-inflammatory and analgesic treatments are based on inhibition of COX activity, the specific alterations observed in this study further our understanding of the relationship of COX-1 and COX-2 with signaling pathways in brain and of the therapeutic and toxicologic consequences of COX inhibition.

Signal transducer and activator of transcription signals in allergic disease

Signal transducer and activator of transcription (STAT) proteins are a group of transcription factors that transmit signals from the extracellular milieu of cells to the nucleus. They are crucial for the signaling of many cytokines that are mediators of allergic inflammation and impact various cell types critical to allergy including epithelial cells, mast cells, lymphocytes, dendritic cells, and eosinophils. Dysregulation of STAT signaling has been implicated in allergic disease, highlighting the importance of these ubiquitous molecules in allergic inflammation and the potential of these pathways as a target for therapeutic intervention. This review will summarize the current understanding of the roles of STAT signaling in allergic disease and the potential of targeting STATs for the treatment of allergic disorders, emphasizing recent observations.

IL-12 p35 silenced dendritic cells modulate immune responses by blocking IL-12 signaling through JAK-STAT pathway in T lymphocytes

Dendritic cells (DC) constitute a complex system of uniquely specialized antigen-presenting cells (APC) that play crucial roles in the initiation and regulation of immune responses. Recent studies have demonstrated that DC silenced by siRNA IL-12 p35 showed tolerogenic capacity in vitro. However, their mechanism of action is not fully understood. In this study, IL-12p35 siRNA was chemically synthesized and transfected into DCs. A coculture of T cells and DCs was performed. After 30 min coculture, T cells were harvested and analyzed. We showed that the IL-12 p35 silenced DCs decreased IL-12-induced T cell responses through blocking tyrosine phosphorylation of JAK2, TYK2, STAT3, and STAT4 proteins in T cells. These results demonstrate IL-12 p35 silenced DCs modulate immune responses by blocking IL-12 signaling through JAK-STAT pathway in T cells.

The brain as a target of inflammation: common pathways link inflammatory and neurodegenerative diseases

Classical knowledge distinguishes between inflammatory and non-inflammatory diseases of the brain. Either the immune system acts on the CNS and initiates a damage cascade, as in autoimmune (e.g. multiple sclerosis) and infectious conditions, or the primary insult is not inflammation but ischemia or degeneration, as in stroke and Alzheimer's disease, respectively. However, as we review here, recent advances have blurred this distinction. On the one hand, the classical inflammatory diseases of the brain also exhibit profound and early neurodegenerative features - remarkably, it has been known for more than a century that neuronal damage is a key feature of multiple sclerosis pathology, yet this was neglected until very recently. On the other hand, immune mechanisms might set the pace of progressive CNS damage in primary neurodegeneration. Despite differing initial events, increasing evidence indicates that even in clinically heterogeneous diseases, there might be common immunological pathways that result in neurotoxicity and reveal targets for more efficient therapies.

The synthetic cannabinoid WIN 55,212-2 increases COX-2 expression and PGE2 release in murine brain-derived endothelial cells following Theiler's virus infection

Brain endothelial cells infection represents one of the first events in the pathogenesis of TMEV-induced demyelination disease (TMEV-IDD), a model of multiple sclerosis (MS). The fact that cyclooxygenase-2 (COX-2) expression in brain endothelium mediates a wide variety of actions during CNS inflammatory diseases such as MS, and that cannabinoids ameliorate the progression of TMEV-IDD, lead us to investigate the role of cannabinoids on COX-2 expression on murine brain endothelial cell cultures subjected or not to TMEV infection. Murine brain endothelial cells (b.end5) express both cannabinoid receptors CB1 and CB2. However, treatment of b.end5 with the cannabinoid agonist WIN 55,212-2 resulted in up-regulation COX-2 protein and PGE2 release by a mechanism independent on activation of these receptors. Other cannabinoids such as 2-arachidonoyl glycerol (2-AG) or the abnormal cannabidiol (Abn-CBD) failed to affect COX-2 in our conditions. TMEV infection of murine brain endothelial cell cultures induced a significant increase of COX-2 expression at 8h, which was maintained even increased, at 20 and 32h post-infection. The combination of TMEV infection and Win 55,212-2 treatment increased COX-2 expression to a greater amount than was seen with either treatment alone. 2-AG and Abn-CBD did not modify COX-2 expression after TMEV. COX-2 synthesis involved different signaling pathways when was induced by WIN 55,212-2 and/or by TMEV infection. WIN 55,212-2-induced COX-2 up-regulation involves the PI(3)K pathway, whereas COX-2 induction by TMEV needs p38 MAPK activation too. Overexpression of COX-2 and the subsequent increase of PGE2 could be affecting flow blood and/or immune reactivity.