Vitamin D and systemic lupus erythematosus: Causality and association with disease activity and therapeutics.

The major role of bioactive vitamin 1,25-dihydroxyvitamin D3 (1,25(OH)2D or calcitriol) is to maintain the levels of calcium and phosphorus to achieve bone and mineral homeostasis. Dietary intake and adequate natural light exposure are the main contributors to normal vitamin D status. In addition to regulating metabolism, vitamin D exerts various immunomodulatory effects that regulate innate and adaptive immunity through immune effector cells such as monocytes, macrophages, T and B lymphocytes, and natural killer cells and nonimmune cells that express vitamin D receptors. Systemic lupus erythematosus (SLE) is an autoimmune disease with an unknown etiology, and the association between vitamin D and SLE remains incompletely understood. Given that the current treatment for SLE relies heavily on corticosteroids and that SLE patients tend to have low vitamin D status, vitamin D supplementation may help to reduce the dosage of corticosteroids and/or attenuate disease severity. In this review, we address the associations between vitamin D and several clinical aspects of SLE. In addition, the underlying immunomodulatory mechanisms accounting for the potential vitamin D-mediated therapeutic effects are discussed. Finally, several confounding factors in data interpretation and the execution of clinical trials and perspectives targeting vitamin D supplementation in patients with SLE are also addressed.

USP18 induction regulates immunometabolism to attenuate M1 signal-polarized macrophages and enhance IL-4-polarized macrophages in systemic lupus erythematosus.

Effective treatment of systemic lupus erythematosus (SLE) remains an unmet need. Different subsets of macrophages play differential roles in SLE and the modulation of macrophage polarization away from M1 status is beneficial for SLE therapeutics. Given the pathogenic roles of type I interferons (IFN-I) in SLE, this study investigated the effects and mechanisms of a mitochondria localization molecule ubiquitin specific peptidase 18 (USP18) preserving anti-IFN effects and isopeptidase activity on macrophage polarization. After observing USP18 induction in monocytes from SLE patients, we studied mouse bone marrow-derived macrophages and showed that USP18 deficiency increased M1signal (LPS + IFN-γ treatment)-induced macrophage polarization, and the effects involved the induction of glycolysis and mitochondrial respiration and the expression of several glycolysis-associated enzymes and molecules, such as hypoxia-inducible factor-1α. Moreover, the effects on mitochondrial activities, such as mitochondrial DNA release and mitochondrial reactive oxygen species production were observed. In contrast, the overexpression of USP18 inhibited M1signal-mediated and enhanced interleukin-4 (IL-4)-mediated polarization of macrophages and the related cellular events. Moreover, the levels of USP18 mRNA expression showed tendency of correlation with the expression of metabolic enzymes in monocytes from patients with SLE. We thus concluded that by preserving anti-IFN effect and downregulating M1 signaling, promoting USP18 activity may serve as a useful approach for SLE therapeutics.

USP18 enhances dengue virus replication by regulating mitochondrial DNA release.

Dengue virus (DENV) infection remains a challenging health threat worldwide. Ubiquitin-specific protease 18 (USP18), which preserves the anti-interferon (IFN) effect, is an ideal target through which DENV mediates its own immune evasion. However, much of the function and mechanism of USP18 in regulating DENV replication remains incompletely understood. In addition, whether USP18 regulates DENV replication merely by causing IFN hyporesponsiveness is not clear. In the present study, by using several different approaches to block IFN signaling, including IFN neutralizing antibodies (Abs), anti-IFN receptor Abs, Janus kinase inhibitors and IFN alpha and beta receptor subunit 1 (IFNAR1)knockout cells, we showed that USP18 may regulate DENV replication in IFN-associated and IFN-unassociated manners. Localized in mitochondria, USP18 regulated the release of mitochondrial DNA (mtDNA) to the cytosol to affect viral replication, and mechanisms such as mitochondrial reactive oxygen species (mtROS) production, changes in mitochondrial membrane potential, mobilization of calcium into mitochondria, 8-oxoguanine DNA glycosylase 1 (OGG1) expression, oxidation and fragmentation of mtDNA, and opening of the mitochondrial permeability transition pore (mPTP) were involved in USP18-regulated mtDNA release to the cytosol. We therefore identify mitochondrial machineries that are regulated by USP18 to affect DENV replication and its association with IFN effects.

Mitochondrial CMPK2 mediates immunomodulatory and antiviral activities through IFN-dependent and IFN-independent pathways.

Mitochondria regulate the immune response after dengue virus (DENV) infection. Microarray analysis of genes identified the upregulation of mitochondrial cytidine/uridine monophosphate kinase 2 (CMPK2) by DENV infection. We used small interfering RNA-mediated knockdown (KD) and CRISPR-Cas9 knockout (KO) approaches, to investigate the role of CMPK2 in mouse and human cells. The results showed that CMPK2 was critical in DENV-induced antiviral cytokine release and mitochondrial oxidative stress and mitochondrial DNA release to the cytosol. The DENV-induced activation of Toll-like receptor (TLR)-9, inflammasome pathway, and cell migration was suppressed by CMPK2 depletion; however, viral production increased under CMPK2 deficiency. Examining mouse bone marrow-derived dendritic cells from interferon-alpha (IFN-α) receptor-KO mice and signal transducer and activator of transcription 1 (STAT1)-KO mice, we confirmed that CMPK2-mediated antiviral activity occurred in IFN-dependent and IFN-independent manners. In sum, CMPK2 is a critical factor in DENV-induced immune responses to determine innate immunity.

Mitochondrial protein CMPK2 regulates IFN alpha-enhanced foam cell formation, potentially contributing to premature atherosclerosis in SLE.

BACKGROUND: Premature atherosclerosis occurs in patients with SLE; however, the mechanisms remain unclear. Both mitochondrial machinery and proinflammatory cytokine interferon alpha (IFN-α) potentially contribute to atherogenic processes in SLE. Here, we explore the roles of the mitochondrial protein cytidine/uridine monophosphate kinase 2 (CMPK2) in IFN-α-mediated pro-atherogenic events. METHODS: Foam cell measurements were performed by oil red O staining, Dil-oxLDL uptake and the BODIPY approach. The mRNA and protein levels were measured by qPCR and Western blotting, respectively. Isolation of CD4+ T cells and monocytes was performed with monoclonal antibodies conjugated with microbeads. Manipulation of protein expression was conducted by either small interference RNA (siRNA) knockdown or CRISPR/Cas9 knockout. The expression of mitochondrial reactive oxygen species (mtROS) was determined by flow cytometry and confocal microscopy. RESULTS: IFN-α enhanced oxLDL-induced foam cell formation and Dil-oxLDL uptake by macrophages. In addition to IFN-α, several triggers of atherosclerosis, including thrombin and IFN-γ, can induce CMPK2 expression, which was elevated in CD4+ T cells and CD14+ monocytes isolated from SLE patients compared to those isolated from controls. The analysis of cellular subfractions revealed that CMPK2 was present in both mitochondrial and cytosolic fractions. IFN-α-induced CMPK2 expression was inhibited by Janus kinase (JAK)1/2 and tyrosine kinase 2 (Tyk2) inhibitors. Both the knockdown and knockout of CMPK2 attenuated IFN-α-mediated foam cell formation, which involved the reduction of scavenger receptor class A (SR-A) expression. CMPK2 also regulated IFN-α-enhanced mtROS production and inflammasome activation. CONCLUSIONS: The study suggests that CMPK2 plays contributing roles in the pro-atherogenic effects of IFN-α.

Epigallocatechin-3-gallate exhibits immunomodulatory effects in human primary T cells.

T cells secrete several inflammatory cytokines that play a critical role in the progression of atherosclerosis. Although green tea epigallocatechin-3-gallate (EGCG) exerts anti-inflammatory and anti-atherosclerotic effects in animals, few studies have identified the mechanism underlying these effects in human primary T cells. This study investigated the pathway involved in EGCG modulation of cytokine secretion in activated human primary T cells. We pre-treated human primary T cells with EGCG (0.1, 1, 5, 10, and 20 µM) for 4 h and incubated them with or without phorbol 12-myristate 13-acetate and ionomycin (P/I) for 20 h. The cytokine production, activator protein (AP)-1 binding activity, and level of mitogen-activated protein kinase (MAPK) were assessed using enzyme-linked immunosorbent assay, electrophoretic mobility shift assay, and Western blotting, respectively. At 10 and 20 µM, EGCG decreased interleukin (IL)-2 levels by 26.0% and 38.8%, IL-4 levels by 41.5% and 55.9%, INF-γ levels by 31.3% and 34.7%, and tumor-necrosis factor (TNF)-α levels by 23.0% and 37.6%, respectively. In addition, the level of phosphorylated c-Jun N-terminal (p-JNK) and extracellular signal-regulated kinase (p-ERK) was decreased, but not the level of p-p38 MAPK. EGCG did not alter any of the total protein amounts, suggesting a selective effect on specific types of MAPKs in stimulated human T cells. EGCG tended to inactivate AP-1 DNA-binding activity. The P/I-induced production of IL-2, IL-4, INF-γ, and TNF-α by human T cells was suppressed by AP-1 inhibitor in a concentration-dependent manner. In conclusion, EGCG suppressed cytokine secretion in activated human primary T cells, and this effect was likely mediated by AP-1 inactivation through the ERK and JNK, but not p38 MAPK, pathways. These results may be related to the mechanisms through which EGCG inhibits immune- or inflammation-related atherogenesis.

Monosodium urate crystals induced ICAM-1 expression and cell-cell adhesion in renal mesangial cells: Implications for the pathogenesis of gouty nephropathy.

BACKGROUND: Renal disease is prevalent in gouty patients and monosodium urate (MSU) crystal deposition in the kidney can be detected in some gouty nephropathy patients. MSU crystals can induce inflammatory events, we investigated the MSU-induced expression of intercellular adhesion molecule (ICAM)-1 on human renal mesangial cells (HRMCs) and the involved signal transduction mechanisms. METHODS: The HRMCs cell line was purchased from ScienCell Research Laboratories. MSU crystals were made by dissolving uric acid in sodium hydroxide (NaOH) solution. The involvement of MAPKs, apoptosis-associated speck-like protein containing a CARD domain (ASC), and Toll-like receptor (TLR) was investigated using pharmacological inhibitors, transfection with short hairpin RNA (shRNA), or monoclonal antibodies. Protein expression was evaluated by Western blotting. The functional activity of ICAM-1 was evaluated with cell-cell adhesion assay and immunofluorescence analysis. RESULTS: MSU stimulation increased expression of ICAM-1 and adhesion between HRMCs and human monocytic THP-1 cells. The interaction between HRMCs and THP-1 was suppressed by ICAM-1 neutralizing antibodies. MSU stimulation induced activation of mitogen-activated protein kinases, including c-Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK), but only p38 was responsible for MSU-induced expression of ICAM-1 and cell-cell adhesion. ASC also play a role in MSU-induced effects. Pretreatment with monoclonal antibodies against toll-like receptor (TLR)2 or TLR4 reduced MSU-induced ICAM-1 expression, cell-cell adhesion, p38 phosphorylation but the reduction of ASC activation is insignificant. CONCLUSION: The MSU induced ICAM-1 expression on HRMCs and cell-cell adhesion involved TLR2/4-p38-ICAM1 pathway and TLR2/4 independent ASC-p38-ICAM1 axis. These findings might partly explain the mechanisms underlying gouty nephropathy.

Compound K inhibits priming and mitochondria-associated activating signals of NLRP3 inflammasome in renal tubulointerstitial lesions.

BACKGROUND: Renal tubulointerstitial lesions (TILs), a key pathological hallmark for chronic kidney disease to progress to end-stage renal disease, feature renal tubular atrophy, interstitial mononuclear leukocyte infiltration and fibrosis in the kidney. Our study tested the renoprotective and therapeutic effects of compound K (CK), as described in our US patent (US7932057B2), on renal TILs using a mouse unilateral ureteral obstruction (UUO) model. METHODS: Renal pathology was performed and renal draining lymph nodes were subjected to flow cytometry analysis. Mechanism-based experiments included the analysis of mitochondrial dysfunction, a model of tubular epithelial cells (TECs) under mechanically induced constant pressure (MICP) and tandem mass tags (TMT)-based proteomics analysis. RESULTS: Administration of CK ameliorated renal TILs by reducing urine levels of proinflammatory cytokines, and preventing mononuclear leukocyte infiltration and fibrosis in the kidney. The beneficial effects clearly correlated with its inhibition of: (i) NF-κB-associated priming and the mitochondria-associated activating signals of the NLRP3 inflammasome; (ii) STAT3 signalling, which in part prevents NLRP3 inflammasome activation; and (iii) the TGF-ß-dependent Smad2/Smad3 fibrotic pathway, in renal tissues, renal TECs under MICP and/or activated macrophages, the latter as a major inflammatory player contributing to renal TILs. Meanwhile, TMT-based proteomics analysis revealed downregulated renal NLRP3 inflammasome activation-associated signalling pathways in CK-treated UUO mice. CONCLUSIONS: The present study, for the first time, presents the potent renoprotective and therapeutic effects of CK on renal TILs by targeting the NLRP3 inflammasome and STAT3 signalling.

Targeting the CD40-CD154 Signaling Pathway for Treatment of Autoimmune Arthritis.

Full activation of T lymphocytes requires signals from both T cell receptors and costimulatory molecules. In addition to CD28, several T cell molecules could deliver costimulatory signals, including CD154, which primarily interacts with CD40 on B-cells. CD40 is a critical molecule regulating several B-cell functions, such as antibody production, germinal center formation and cellular proliferation. Upregulated expression of CD40 and CD154 occurs in immune effector cells and non-immune cells in different autoimmune diseases. In addition, therapeutic benefits have been observed by blocking the CD40-CD154 interaction in animals with collagen-induced arthritis. Given the therapeutic success of the biologics abatacept, which blocks CD28 costimulation, and rituximab, which deletes B cells in the treatment of autoimmune arthritis, the inhibition of the CD40-CD154 axis has two advantages, namely, attenuating CD154-mediated T cell costimulation and suppressing CD40-mediated B-cell stimulation. Furthermore, blockade of the CD40-CD154 interaction drives the conversion of CD4+ T cells to regulatory T cells that mediate immunosuppression. Currently, several biological products targeting the CD40-CD154 axis have been developed and are undergoing early phase clinical trials with encouraging success in several autoimmune disorders, including autoimmune arthritis. This review addresses the roles of the CD40-CD154 axis in the pathogenesis of autoimmune arthritis and its potential as a therapeutic target.

Pitavastatin Exerts Potent Anti-Inflammatory and Immunomodulatory Effects via the Suppression of AP-1 Signal Transduction in Human T Cells.

Statins inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase are the standard treatment for hypercholesterolemia in atherosclerotic cardiovascular disease (ASCVD), mediated by inflammatory reactions within vessel walls. Several studies highlighted the pleiotropic effects of statins beyond their lipid-lowering properties. However, few studies investigated the effects of statins on T cell activation. This study evaluated the immunomodulatory capacities of three common statins, pitavastatin, atorvastatin, and rosuvastatin, in activated human T cells. The enzyme-linked immunosorbent assay (ELISA) and quantitative real time polymerase chain reaction (qRT-PCR) results demonstrated stronger inhibitory effects of pitavastatin on the cytokine production of T cells activated by phorbol 12-myristate 13-acetate (PMA) plus ionomycin, including interleukin (IL)-2, interferon (IFN)-γ, IL-6, and tumor necrosis factor α (TNF-α). Molecular investigations revealed that pitavastatin reduced both activating protein-1 (AP-1) DNA binding and transcriptional activities. Further exploration showed the selectively inhibitory effect of pitavastatin on the signaling pathways of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal kinase (JNK). Our findings suggested that pitavastatin might provide additional benefits for treating hypercholesterolemia and ASCVD through its potent immunomodulatory effects on the suppression of ERK/p38/AP-1 signaling in human T cells.

Anti-inflammatory and anti-osteoarthritis effects of Cm-02 and Ck-02.

Osteoarthritis (OA) is a common degenerative joint disease characterized by progressive deterioration of articular cartilage. There have been reports that small molecule inhibitors have anti-osteoarthritis effects; however, the effects of 3-(4-chloro-2-fluorophenyl)-6-(2,4-difluorophenyl)-2H-benzo[e] [1,3]oxazine-2,4(3H)-dione (Cm-02) and 6-(2,4-difluorophenyl)-3-(3,4-difluorophenyl)-2H-benzo[e] [1,3]oxazine-2,4(3H)-dione (Ck-02), small molecule inhibitors which share many structural similarities with quercetin (a potent anti-inflammatory flavonoid), remain unclear. In this study, TNF-α-stimulated porcine and human chondrocyte models were used to investigate the inhibitory effects of Cm-02 and Ck-02 on the molecular mechanisms underlying the anti-OA effects. TNF-α was used to stimulate porcine and human chondrocytes to mimic immunomodulatory potency in-vitro. Anti-osteoarthritic effects were characterized in terms of protein and mRNA levels associated with the pathogenesis of OA. We also examined (1) the inducible nitric oxide synthase (iNOS)-nitric oxide (NO) system in cultured chondrocytes, (2) matrix metalloproteinases (MMPs) in cultured chondrocytes, and (3) aggrecan degradation in cartilage explants. Finally, we tested the activation of nuclear factor-kappaB (NF-κB), interferon regulatory factor-1 (IRF-1), and activate the protein-1 (AP-1), and we tested the signal transduction and activation of transcription-3 (STAT-3). Our results indicate that, in chondrocytes, Cm-02 and Ck-02 inhibit TNF-α induced NO production, iNOS, MMP, the expression of disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), and the enzyme activity of MMP-13. Furthermore, both Cm-02 and Ck-02 were found to stimulate TNF-α, which has been shown to suppress the activation of several transcription factors, including NF-κB, STAT-3, and IRF-1 in porcine and human chondrocytes. Cm-02 and Ck-02 were also found to help prevent the release of proteoglycans from cartilage explants. Our findings demonstrate that both Cm-02 and Ck-02 have potent anti-inflammatory activities and the ability to protect cartilage in an OA cell model. These findings indicate that Cm-02 and Ck-02 have the potential to be further developed for the therapeutic treatment of OA.

Useful message in choosing optimal biological agents for patients with autoimmune arthritis.

The introduction of biological disease-modifying antirheumatic drug (bDMARD) treatments for various types of autoimmune arthritis, such as rheumatoid arthritis, psoriatic arthropathy and ankylosing spondylitis, represents a new era of treatment for patients with a refractory response to conventional synthetic DMARDs (csDMARDs). Many new bDMARDs with different modalities or that target different pro-inflammatory molecules, likely cytokines, are rapidly emerging. Hence, physicians in the field may be confused about choosing appropriate bDMARDs for their patients. Considering the high cost of bDMARDs and the rapid destructive process of autoimmune arthritis in patients, the choice of optimal bDMARDs for patients who fail to respond or show an inadequate therapeutic response to csDMARDs designed to control the disease is very critical. Here, we summarize the strengths and weaknesses of bDMARDs and specifically focus on their uses in patients with comorbid conditions or with specific medical conditions, such as pregnancy. This commentary provides a solid up-to-date review on commercially available bDMARDs and very useful information for physicians to facilitate the choice of more appropriate bDMARDs to treat patients with autoimmune arthritis and for basic researchers to understand the current strategies of bDMARD usage and hopefully to develop more powerful bDMARDs with fewer safety concerns.

Spices and Atherosclerosis.

Cardiovascular disease is one of the leading causes of death and disability in the world. Atherosclerosis, characterized by lipid accumulation and chronic inflammation in the vessel wall, is the main feature of cardiovascular disease. Although the amounts of fruits and vegetables present in the diets vary by country, diets, worldwide, contain large amounts of spices; this may have positive or negative effects on the initiation and development of atherosclerosis. In this review, we focused on the potential protective effects of specific nutrients from spices, such as pepper, ginger, garlic, onion, cinnamon and chili, in atherosclerosis and atherosclerotic cardiovascular disease. The mechanisms, epidemiological analysis, and clinical studies focusing on a variety of spices are covered in this review. Based on the integrated information, we aimed to raise specific recommendations for people with different dietary styles for the prevention of atherosclerotic cardiovascular disease through dietary habit adjustments.

Operation of mitochondrial machinery in viral infection-induced immune responses.

Mitochondria have been recognized as ancient bacteria that contain evolutionary endosymbionts. Metabolic pathways and inflammatory signals interact within mitochondria in response to different stresses, such as viral infections. In this commentary, we address several interesting questions, including (1) how do mitochondrial machineries participate in immune responses; (2) how do mitochondria mediate antiviral immunity; (3) what mechanisms involved in mitochondrial machinery, including the downregulation of mitochondrial DNA (mtDNA), disturbances of mitochondrial dynamics, and the induction of mitophagy and regulation of apoptosis, have been adopted by viruses to evade antiviral immunity; (4) what mechanisms involve the regulation of mitochondrial machineries in antiviral therapeutics; and (5) what are the potential challenges and perspectives in developing mitochondria-targeting antiviral treatments? This commentary provides a comprehensive review of the roles and mechanisms of mitochondrial machineries in immunity, viral infections and related antiviral therapeutics.

Infection with the dengue RNA virus activates TLR9 signaling in human dendritic cells.

Toll-like receptors (TLRs) are important sensors that recognize pathogen-associated molecular patterns. Generally, TLR9 is known to recognize bacterial or viral DNA but not viral RNA and initiate an immune response. Herein, we demonstrate that infection with dengue virus (DENV), an RNA virus, activates TLR9 in human dendritic cells (DCs). DENV infection induces release of mitochondrial DNA (mtDNA) into the cytosol and activates TLR9 signaling pathways, leading to production of interferons (IFNs). The DENV-induced mtDNA release involves reactive oxygen species generation and inflammasome activation. DENV infection disrupts the association between transcription factor A mitochondria (TFAM) and mtDNA and activates the mitochondrial permeability transition pores. The side-by-side comparison of TLR9 and cyclic GMP-AMP synthase (cGAS) knockdown reveals that both cGAS and TLR9 comparably contribute to DENV-induced immune activation. The significance of TLR9 in DENV-induced immune response is also confirmed in examination with the bone marrow-derived DCs prepared from Tlr9-knockout mice. Our study unravels a previously unrecognized phenomenon in which infection with an RNA virus, DENV, activates TLR9 signaling by inducing mtDNA release in human DCs.

Arthroprotective Effects of Cf-02 Sharing Structural Similarity with Quercetin.

In this study, we synthesized hundreds of analogues based on the structure of small-molecule inhibitors (SMIs) that were previously identified in our laboratory with the aim of identifying potent yet safe compounds for arthritis therapeutics. One of the analogues was shown to share structural similarity with quercetin, a potent anti-inflammatory flavonoid present in many different fruits and vegetables. We investigated the immunomodulatory effects of this compound, namely 6-(2,4-difluorophenyl)-3-(3-(trifluoromethyl)phenyl)-2H-benzo[e][1,3]oxazine-2,4(3H)-dione (Cf-02), in a side-by-side comparison with quercetin. Chondrocytes were isolated from pig joints or the joints of patients with osteoarthritis that had undergone total knee replacement surgery. Several measures were used to assess the immunomodulatory potency of these compounds in tumor necrosis factor (TNF-α)-stimulated chondrocytes. Characterization included the protein and mRNA levels of molecules associated with arthritis pathogenesis as well as the inducible nitric oxide synthase (iNOS)⁻nitric oxide (NO) system and matrix metalloproteinases (MMPs) in cultured chondrocytes and proteoglycan, and aggrecan degradation in cartilage explants. We also examined the activation of several important transcription factors, including nuclear factor-kappaB (NF-κB), interferon regulatory factor-1 (IRF-1), signal transducer and activator of transcription-3 (STAT-3), and activator protein-1 (AP-1). Our overall results indicate that the immunomodulatory potency of Cf-02 is fifty-fold more efficient than that of quercetin without any indication of cytotoxicity. When tested in vivo using the induced edema method, Cf-02 was shown to suppress inflammation and cartilage damage. The proposed method shows considerable promise for the identification of candidate disease-modifying immunomodulatory drugs and leads compounds for arthritis therapeutics.

Chondroprotective Effects and Mechanisms of Dextromethorphan: Repurposing Antitussive Medication for Osteoarthritis Treatment.

Osteoarthritis (OA) is the most common joint disorder and primarily affects older people. The ideal anti-OA drug should have a modest anti-inflammatory effect and only limited or no toxicity for long-term use. Because the antitussive medication dextromethorphan (DXM) is protective in atherosclerosis and neurological diseases, two common disorders in aged people, we examined whether DXM can be protective in pro-inflammatory cytokine-stimulated chondrocytes and in a collagen-induced arthritis (CIA) animal model in this study. Chondrocytes were prepared from cartilage specimens taken from pigs or OA patients. Western blotting, quantitative PCR, and immunohistochemistry were adopted to measure the expression of collagen II (Col II) and matrix metalloproteinases (MMP). DXM significantly restored tumor necrosis factor-alpha (TNF-α)-mediated reduction of collagen II and decreased TNF-α-induced MMP-13 production. To inhibit the synthesis of MMP-13, DXM blocked TNF-α downstream signaling, including I kappa B kinase (IKK)α/ß-IκBα-nuclear factor-kappaB (NF-κB) and c-Jun N-terminal kinase (JNK)-activator protein-1 (AP-1) activation. Besides this, DXM protected the CIA mice from severe inflammation and cartilage destruction. DXM seemed to protect cartilage from inflammation-mediated matrix degradation, which is an irreversible status in the disease progression of osteoarthritis. The results suggested that testing DXM as an osteoarthritis therapeutic should be a focus in further research.

Translational Implication of Galectin-9 in the Pathogenesis and Treatment of Viral Infection.

The interaction between galectin-9 and its receptor, Tim-3, triggers a series of signaling events that regulate immune responses. The expression of galectin-9 has been shown to be increased in a variety of target cells of many different viruses, such as hepatitis C virus (HCV), hepatitis B virus (HBV), herpes simplex virus (HSV), influenza virus, dengue virus (DENV), and human immunodeficiency virus (HIV). This enhanced expression of galectin-9 following viral infection promotes significant changes in the behaviors of the virus-infected cells, and the resulting events tightly correlate with the immunopathogenesis of the viral disease. Because the human immune response to different viral infections can vary, and the lack of appropriate treatment can have potentially fatal consequences, understanding the implications of galectin-9 is crucial for developing better methods for monitoring and treating viral infections. This review seeks to address how we can apply the current understanding of galectin-9 function to better understand the pathogenesis of viral infection and better treat viral diseases.

JNK/AP-1 activation contributes to tetrandrine resistance in T-cell acute lymphoblastic leukaemia.

T-cell acute lymphoblastic leukaemia (T-ALL) is a challenging malignancy with a high relapse rate attributed to drug resistance. Tetrandrine (TET), a bisbenzylisoquinoline alkaloid extracted from a Chinese herb, is a potential anti-cancer and anti-leukaemic drug. In this study we investigated the mechanisms of TET resistance in T-ALL cells in vitro. Among the four T-ALL cell lines tested, Jurkat and CEM cells exhibited the lowest and highest resistance to TET with IC50 values at 24 h of 4.31±0.12 and 16.53±3.32 µmol/L, respectively. When treated with TET, the activity of transcription factor activator protein 1 (AP-1) was significantly decreased in Jurkat cells but nearly constant in CEM cells. To avoid cell-specific variation in drug resistance and transcription factor activities, we established a TET-R Jurkat subclone with the estimated IC50 value of 10.90±.92 µmol/L by exposing the cells to increasing concentrations of TET. Interestingly, when treated with TET, TET-R Jurkat cells exhibited enhanced AP-1 and NF-κB activity, along with upregulation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) signaling pathways, whereas the expression of P-gp was not altered. Selective inhibition of JNK but not ERK suppressed AP-1 activity and TET resistance in TET-R Jurkat cells and in CEM cells. These results demonstrate that Jurkat cells acquire TET resistance through activation of the JNK/AP-1 pathway but not through P-gp expression. The JNK/AP-1 pathway may be a potential therapeutic target in relapsed T-ALL.

Physiological concentrations of soluble uric acid are chondroprotective and anti-inflammatory.

High uric acid levels are a risk factor for cardiovascular disorders and gout; however, the role of physiological concentrations of soluble uric acid (sUA) is poorly understood. This study aimed to clarify the effects of sUA in joint inflammation. Both cell cultures of primary porcine chondrocytes and mice with collagen-induced arthritis (CIA) were examined. We showed that sUA inhibited TNF-α- and interleukin (IL)-1ß-induced inducible nitric oxide synthase, cyclooxygenase-2 and matrix metalloproteinase (MMP)-13 expression. Examination of the mRNA expression of several MMPs and aggrecanases confirmed that sUA exerts chondroprotective effects by inhibiting the activity of many chondro-destructive enzymes. These effects attenuated collagen II loss in chondrocytes and reduced proteoglycan degradation in cartilage explants. These results were reproduced in chondrocytes cultured in three-dimensional (3-D) alginate beads. Molecular studies revealed that sUA inhibited the ERK/AP-1 signalling pathway, but not the IκBα-NF-κB signalling pathway. Increases in plasma uric acid levels facilitated by the provision of oxonic acid, a uricase inhibitor, to CIA mice exerted both anti-inflammatory and arthroprotective effects in these animals, as demonstrated by their arthritis severity scores and immunohistochemical analysis results. Our study demonstrated that physiological concentrations of sUA displayed anti-inflammatory and chondroprotective effects both in vitro and in vivo.