Chemokine-enhanced migration of human peripheral blood mononuclear cells is antagonized by interferon beta-1b through an effect on matrix metalloproteinase-9

The role of STING signaling in central nervous system infection and neuroinflammatory disease

The cyclic guanosine monophosphate-adenosine monophosphate (GMP-AMP) synthase-Stimulator of Interferon Genes (cGAS-STING) pathway is a critical innate immune mechanism for detecting the presence of double-stranded DNA (dsDNA) and prompting a robust immune response. Canonical cGAS-STING activation occurs when cGAS, a predominantly cytosolic pattern recognition receptor, binds microbial DNA to promote STING activation. Upon STING activation, transcription factors enter the nucleus to cause the production of Type I interferons, inflammatory cytokines whose primary function is to prime the host for viral infection by producing a number of antiviral interferon-stimulated genes. While the pathway was originally described in viral infection, more recent studies have implicated cGAS-STING signaling in a number of different contexts, including autoimmune disease, cancer, injury, and neuroinflammatory disease. This review focuses on how our understanding of the cGAS-STING pathway has evolved over time with an emphasis on the role of STING-mediated neuroinflammation and infection in the nervous system. We discuss recent findings on how STING signaling contributes to the pathology of pain, traumatic brain injury, and stroke, as well as how mitochondrial DNA may promote STING activation in common neurodegenerative diseases. We conclude by commenting on the current knowledge gaps that should be filled before STING can be an effective therapeutic target in neuroinflammatory disease. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology Infectious Diseases > Molecular and Cellular Physiology Immune System Diseases > Molecular and Cellular Physiology.

Chemokine-Capturing Wound Contact Layer Rescues Dermal Healing

Excessive inflammation often impedes the healing of chronic wounds. Scavenging of chemokines by multiarmed poly(ethylene glycol)-glycosaminoglycan (starPEG-GAG) hydrogels has recently been shown to support regeneration in a diabetic mouse chronic skin wound model. Herein, a textile-starPEG-GAG composite wound contact layer (WCL) capable of selectively sequestering pro-inflammatory chemokines is reported. Systematic variation of the local and integral charge densities of the starPEG-GAG hydrogel component allows for tailoring its affinity profile for biomolecular signals of the wound milieu. The composite WCL is subsequently tested in a large animal (porcine) model of human wound healing disorders. Dampening excessive inflammatory signals without affecting the levels of pro-regenerative growth factors, the starPEG-GAG hydrogel-based WCL treatment induced healing with increased granulation tissue formation, angiogenesis, and deposition of connective tissue (collagen fibers). Thus, this biomaterials technology expands the scope of a new anti-inflammatory therapy toward clinical use.

Microglia response following acute demyelination is heterogeneous and limits infiltrating macrophage dispersion

Microglia and infiltrating macrophages are thought to orchestrate the central nervous system (CNS) response to injury; however, the similarities between these cells make it challenging to distinguish their relative contributions. We genetically labeled microglia and CNS-associated macrophages to distinguish them from infiltrating macrophages. Using single-cell RNA sequencing, we describe multiple microglia activation states, one of which was enriched for interferon associated signaling. Although blood-derived macrophages acutely infiltrated the demyelinated lesion, microglia progressively monopolized the lesion environment where they surrounded infiltrating macrophages. In the microglia-devoid sciatic nerve, the infiltrating macrophage response was sustained. In the CNS, the preferential proliferation of microglia and sparse microglia death contributed to microglia dominating the lesion. Microglia ablation reversed the spatial restriction of macrophages with the demyelinated spinal cord, highlighting an unrealized macrophages-microglia interaction. The restriction of peripheral inflammation by microglia may be a previously unidentified mechanism by which the CNS maintains its "immune privileged" status.

The role of B cells in multiple sclerosis: Current and future therapies

While it was long held that T cells were the primary mediators of multiple sclerosis (MS) pathogenesis, the beneficial effects observed in response to treatment with Rituximab (RTX), a monoclonal antibody (mAb) targeting CD20, shed light on a key contributor to MS that had been previously underappreciated: B cells. This has been reaffirmed by results from clinical trials testing the efficacy of subsequently developed B cell-depleting mAbs targeting CD20 as well as studies revisiting the effects of previous disease-modifying therapies (DMTs) on B cell subsets thought to modulate disease severity. In this review, we summarize current knowledge regarding the complex roles of B cells in MS pathogenesis and current and potential future B cell-directed therapies.

Matrix metalloproteinase 28 is regulated by TRIF- and type I IFN-dependent signaling in macrophages

Matrix metalloproteinases (MMPs) are transcriptionally regulated proteases that have multiple roles in modifying the extracellular matrix (ECM) and inflammatory response. Our previous work identified Mmp28 as a key regulator of inflammation and macrophage polarization during experimental models of pulmonary infection, fibrosis, and chronic smoke exposure. However, the signaling pathways responsible for regulation of macrophage Mmp28 expression remain undefined. This study utilized murine macrophages obtained from wild type, Tlr2^-/-, Tlr4^-/-, MyD88^-/-, Ticam1 ^Lps2 ( Trif_mutant), and Ifnar1^-/- mice to test the hypothesis that macrophage Mmp28 expression was dependent on TRIF and type I IFN. Our results support the hypothesis, demonstrating that increased macrophage Mmp28 expression was dependent on type I IFN after LPS and poly(I:C) stimulation. To gain further insight into the function of MMP28, we explored the inflammatory response of macrophages derived from wild type or Mmp28^-/- mice to stimulation with poly(I:C). Our data support a role for MMP28 in regulating the macrophage inflammatory response to poly(I:C) because expression of Ccl2, Ccl4, Cxcl10, and Il6 were increased in Mmp28^-/- macrophages. Together, these data support a model in which macrophages integrate TRIF- and type I IFN-dependent signaling to coordinate regulation of proteins with the capacity to modify the ECM.

B-cell-targeted therapies in relapsing forms of MS

In recent years, there has been a significant increase in the therapeutic options available for the management of relapsing forms of MS. Therapies primarily targeting B cells, including therapeutic anti-CD20 monoclonal antibodies, have been evaluated in phase I, phase II, and phase III clinical trials. Results of these trials have shown their efficacy and relatively tolerable adverse effect profiles, suggesting a favorable benefit-to-risk ratio. In this review, we discuss the pathogenic role of B cells in MS and the rationale behind the utilization of B-cell depletion as a therapeutic cellular option. We also discuss the data of clinical trials for anti-CD20 antibodies in relapsing forms of MS and existing evidence for other B-cell–directed therapeutic strategies.

Impairment of human neural crest cell migration by prolonged exposure to interferon-beta

Human cell-based toxicological assays have been used successfully to detect known toxicants, and to distinguish them from negative controls. However, there is at present little experience on how to deal with hits from screens of compounds with yet unknown hazard. As a case study to this issue, we characterized human interferon-beta (IFNβ) as potential developmental toxicant affecting neural crest cells (NCC). The protein was identified as a hit during a screen of clinically used drugs in the ‘migration inhibition of neural crest’ (MINC) assay. Concentration–response studies in the MINC combined with immunocytochemistry and mRNA quantification of cellular markers showed that IFNβ inhibited NCC migration at concentrations as low as 20 pM. The effective concentrations found here correspond to levels found in human plasma, and they were neither cytostatic nor cytotoxic nor did they did they affect the differentiation state and overall phenotype of NCC. Data from two other migration assays confirmed that picomolar concentration of IFNβ reduced the motility of NCC, while other interferons were less potent. The activation of JAK kinase by IFNβ, as suggested by bioinformatics analysis of the transcriptome changes, was confirmed by biochemical methods. The degree and duration of pathway activation correlated with the extent of migration inhibition, and pharmacological block of this signaling pathway before, or up to 6 h after exposure to the cytokine prevented the effects of IFNβ on migration. Thus, the reduction of vital functions of human NCC is a hitherto unknown potential hazard of endogenous or pharmacologically applied interferons.

Increased Expression of p-Akt correlates with Chronic Allograft Nephropathy in a Rat Kidney Model

Chronic allograft nephropathy (CAN) is the most common cause of chronic graft dysfunction leading to graft failure, our study investigates the expression and significance of p-Akt in the pathogenesis of CAN in rats. Kidneys of Fisher (F344) rats were orthotopically transplanted into Lewis (LEW) rats. The animals were evaluated at 4, 8, 12, 16, and 24 weeks post-transplantation for renal function and histopathology. Phosphorate Akt (p-Akt) protein expression was determined by Western blot and immunohistological assays. Our data show that 24-h urinary protein excretion in CAN rats increased significantly at week 16 as compared with F344/LEW controls. Allografts got severe interstitial infiltration of mononuclear cells at week 4 and week 8, but it was degraded as the time went on after week 16. Allografts markedly presented with severe interstitial fibrosis (IF) and tubular atrophy at 16 and 24 weeks. p-Akt expression was upregulated in rat kidneys with CAN, and the increase became more significant over time after transplantation. p-Akt expression correlated significantly with 24-h urinary protein excretion, serum creatinine levels, tubulointerstitial mononuclear cells infiltration, smooth muscle cells (SMCs) migration in vascular wall, and IF. It was concluded that p-Akt overexpression might be the key event that involved mononuclear cells infiltration and vascular SMCs migration at early stage, and IF and allograft nephroangiosclerosis at the late stage of CAN pathogenesis in rats.

Elevated endothelial microparticle—monocyte complexes induced by multiple sclerosis plasma and the inhibitory effects of interferon-β1b on release of endothelial microparticles, formation and transendothelial migration of monocyte-endothelial microparticle complexes

Monocyte migration through the disrupted cerebral endothelial cell (EC) junctions plays an essential role in formation of multiple sclerosis (MS) demyelinating lesions. During pathogenesis of MS, activated ECs release endothelial microparticles (EMP), which possibly facilitate transendothelial migration (TEMIG) of monocytes. To assess functional roles of EMP in MS, specifically, their (i) interaction with monocytes, (ii) effect on monocyte TEMIG in an in vitro model of the brain microvascular endothelial cells (BMVEC), (iii) phenotypic profiles of EMP elicited by MS plasma and (iv) the effects of IFN-b1b on release of EMP and on TEMIG of monocytes (mono) and monocytes:EMP complexes (mono:EMP) through the BMVEC. The effect of IFN-b1b on the release of EMP and the TEMIG of mono and mono:EMP was assessed by preincubating BMVEC cultures of IFN-b1b prior to addition of plasma. Three EMP phenotypes, CD54, CD62E and CD31 were assayed. Plasma specimens from 20 patients with relapsing—remitting MS (11 in exacerbation, MS-E, and 9 in remission, ME-R) and 10 healthy controls were studied. Incubation of BMVEC with MS-E plasma yielded elevated levels of EMPCD54, EMP62E and EMPCD31 relative to MS-R and control plasmas. MS-E but not MS-R or control plasma also augmented TEMIG of monocytes, respectively. Mono:EMP complexes further augmented TEMIG relative to mono alone, but only in the presence of MS-E plasma; there was no significant effect with MS-R or control plasmas. The presence of IFN-b1b inhibited TEMIG of mono and mono:EMP by 20% and 30%, respectively. MS-E but not MS-R plasma elicited release of activation-derived EMP and enhanced TEMIG of mono and mono:EMP. IFN-b1b inhibited TEMIG and release of EMP, suggesting a role of EMP and a novel therapeutic mechanism for IFN-β1b in MS.

Gene expression analysis during recovery process indicates the mechanism for innate immune injury and repair from Coxsackievirus B3-induced myocarditis

To investigate the innate immune injury and repair mechanism during recovery from Coxsackievirus B3 (CVB3) induced myocarditis, we established an acute viral myocarditis recovery model by infecting BALB/c mice with CVB3. Histopathological examination of cardiac tissues after infection showed a gradual increase of myocardial injury to the maximum degree at 8 dpi (days post infection), followed by a recovery process with reduced viral replication. We also measured expression changes of innate immune genes in heart after 4, 8 and 12 days of infection using innate immune real-time PCR array. The results showed expression alterations in many Pattern Recognition Receptors (PRRs) genes upon CVB3 infection, which activated multiple important signaling pathways during recovery process. The expression of TLRs, RLRs, PKR and cytokines were strongly induced and reached the peak at 4 dpi in early myocarditis stage, followed by a gradual reduction in recovery stage, during which the levels were even lower than normal at 12 dpi. The strong correlation between cardiac histopathology score and chemokine expression level suggested that the chemokines might play a role in pathological changes during early myocarditis stage. In addition, we also found that both cell survival signaling pathways (AKT1, p38MAPK) and antiviral signaling pathways (IKKα/β/ε) were activated and promoted the recovery during late myocarditis stage. Altogether, our observations improved the understanding of formation and progression of the pathological lesions, as well as the repair mechanism for acute viral myocarditis.

Interferon-β gene transfer inhibits melanoma cells adhesion and migration

We evaluated the effects of expression of interferon-β (IFNβ) after lipofection on melanoma cells adhesion and migration. Three canine mucosal (Ak, Br and Ol) and one human dermal (SB2) melanomas were assayed. By means of the wound healing assay, we found a significant inhibitory effect of canine IFNβ gene expression on cells migration in Br and Ol monolayers. This effect could be reproduced on unlipofected Ol cells with conditioned culture media obtained from canine IFNβ gene-lipofected Ol cells, and with recombinant human IFNβ on unlipofected SB2 cells. Furthermore, IFNβ gene expression of the four tested tumor cells significantly inhibited their adhesion to extracellular matrix (ECM) proteins and their spreading from multicellular spheroids onto gelatin coating. The addition of catalase reverted the increase of reactive oxygen species (ROS) in Ol cells and the inhibition of cell migration in monolayers (Ol) and spheroids (Ol an SB2) produced by canine and human IFNβ expression, suggesting the involvement of ROS as mediators of IFNβ action on the cells interactions with ECM. Together with its known immune, antiangiogenic and cytotoxic effects, the present data strongly support more studies exploring the clinical potential of IFNβ for cancer therapy.

Curcuminoids Modulate the PKCδ/NADPH Oxidase/Reactive Oxygen Species Signaling Pathway and Suppress Matrix Invasion during Monocyte-Macrophage Differentiation

Monocyte recruitment and invasion play critical roles in the initiation and progression of atherosclerosis. The reduction in monocyte adhesion and infiltration is thought to exert antiatherosclerotic effects. Curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) are the major active components of curcuminoids and exhibit several biological activities, including anti-inflammatory, anticarcinogenic, and hypocholesterolemic activities. The aim of this study was to investigate the antiatherogenic effects and mechanisms of curcuminoids during monocyte to macrophage differentiation. The results showed that curcumin, DMC, and BDMC (20 μM) suppressed matrix invasion from 100.0 ± 5.0% to 24.8 ± 1.4%, 26.6 ± 2.9%, and 33.7 ± 1.7%, respectively, during PMA-induced THP-1 differentiation. We found that curcuminoids significantly reduced PMA-induced CD11b and MMP-9 expression by THP-1 cells. Production of reactive oxygen species (ROS) induced by PMA (126.7 ± 2.1%) was markedly attenuated by curcumin, DMC, and BDMC to 99.5 ± 7.8%, 87.8 ± 8.2%, and 89.8 ± 7.6%, respectively, resulting in the down-regulation of CD11b and MMP-9 expression. We demonstrated that curcuminoids inhibited NADPH oxidase through the down-regulation of NOX2 expression and the reduction of p47phox membrane translocation. Moreover, we found involvement of PKCδ in the PMA-induced NOX2, CD11b, and MMP-9 mRNA expression. Curcumin, DMC, and BDMC decreased the active form of PKCδ protein stimulated by PMA in THP-1 cells. Overall, our results reveal that curcuminoids suppress matrix invasion through the inhibition of the PKCδ/NADPH oxidase/ROS signaling pathway during monocyte-macrophage differentiation.

Emerging roles of endothelial cells in multiple sclerosis pathophysiology and therapy

Although multiple sclerosis (MS) has traditionally been viewed and researched as an immune-mediated demyelinating and neurodegenerative disease of the human central nervous system (CNS), its highly complex pathogenesis clearly includes a significant vascular inflammatory component and many therapeutic approaches achieve benefit by direct or indirect effects on cerebrovascular endothelial cells. Cerebral endothelial cells create and separate the compartments of the peripheral circulation and CNS creating the blood-brain barrier (BBB), a selectively permeable boundary layer between these spaces. Interactions between activated leukocytes and cerebral endothelium play essential roles in mediating their trans-BBB diapedesis during normal immune surveillance and during pathogenesis of neuroinflammatory diseases like MS. Extravasation of activated and committed leukocytes from the peripheral circulation through the endothelial layer of the BBB into the CNS milieu is the most fundamental step in formation of MS lesions. During MS pathogenesis, once the activated leukocytes enter the CNS environment, they propagate a massive wave of destruction which culminates in the loss of both myelin/oligodendrocyte complex and neurodegeneration. Multiple clinical and basic scientific observations support endothelial cell 'stress' and apoptosis as a hallmark characteristic of MS. The manipulation of the endothelial biology aiming to block trans-endothelial migration of activated immune cells into the CNS is a potent form of treatment for MS achieving significant reductions in disease activity and new lesion formation. In particular, endothelial microparticles are now well-recognized as important biomarkers and mediators of this type of stress. In this review, we discuss recent findings and new advances in our knowledge regarding leukocyte migration through the endothelial frontier of the BBB and how this can be exploited toward treating MS patients.

Valproic acid ameliorates inflammation in experimental autoimmune encephalomyelitis rats

Valproic acid (VPA) is a short-chain branched fatty acid with anti-inflammatory, neuro-protective and axon remodeling effects. Here we have studied effects of VPA in gpMBP(68-84)-induced experimental autoimmune encephalomyelitis (EAE). Both preventive (from Day 0 to Day 18) and therapeutic (from Day 7 to Day 18 or from Day 9 to Day 19) VPA (500 mg/kg, intra-gastric) administration to EAE rats once daily greatly reduced the severity and duration of EAE, and suppressed mRNA levels of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-17, matrix metalloproteinase 9 (MMP9), inducible nitric oxide synthase (iNOS) and transcription factor T-bet, but increased levels of IL-4 mRNA in EAE spinal cords. Furthermore, preventive VPA treatment greatly attenuated accumulation of macrophages and lymphocytes in EAE spinal cords. VPA treatment altered the cytokine milieu of lymph nodes, modulating the Th profile from Th1 and Th17 to a profile of Th2 and regulatory T cells. In addition, in vitro study showed that VPA inhibited non-specific lymphocyte proliferation in a dose-dependent manner. In summary, our data demonstrated that VPA could suppress systemic and local inflammation to improve outcome of EAE, suggesting that VPA might be a candidate for treatment of multiple sclerosis.

Interferon regulatory factor-7 modulates experimental autoimmune encephalomyelitis in mice

Background

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) with unknown etiology. Interferon-β (IFN-β), a member of the type I IFN family, is used as a therapeutic for MS and the IFN signaling pathway is implicated in MS susceptibility. Interferon regulatory factor 7 (IRF7) is critical for the induction and positive feedback regulation of type I IFN. To establish whether and how endogenous type I IFN signaling contributes to disease modulation and to better understand the underlying mechanism, we examined the role of IRF7 in the development of MS-like disease in mice.

Methods

The role of IRF7 in development of EAE was studied by immunizing IRF7-KO and C57BL/6 (WT) mice with myelin oligodendrocyte glycoprotein using a standard protocol for the induction of EAE. We measured leukocyte infiltration and localization in the CNS using flow cytometric analysis and immunohistochemical procedures. We determined levels of CD3 and selected chemokine and cytokine gene expression by quantitative real-time PCR.

Results

IRF7 gene expression increased in the CNS as disease progressed. IRF7 message was localized to microglia and infiltrating leukocytes. Furthermore, IRF7-deficient mice developed more severe disease. Flow cytometric analysis showed that the extent of leukocyte infiltration into the CNS was higher in IRF7-deficient mice with significantly higher number of infiltrating macrophages and T cells, and the distribution of infiltrates within the spinal cord was altered. Analysis of cytokine and chemokine gene expression by quantitative real-time PCR showed significantly greater increases in CCL2, CXCL10, IL-1β and IL17 gene expression in IRF7-deficient mice compared with WT mice.

Conclusion

Together, our findings suggest that IRF7 signaling is critical for regulation of inflammatory responses in the CNS.

Cilostazol inhibits matrix invasion and modulates the gene expressions of MMP-9 and TIMP-1 in PMA-differentiated THP-1 cells

The invasion of monocytes into the subendothelium space plays an important role in the early stage of atherosclerosis. Cilostazol, a specific phosphodiesterase type III (PDE3) inhibitor, has been shown to exhibit anti-atherosclerotic effect. The present study aimed to investigate the modulating effects of cilostazol on monocyte invasion and the gene expressions of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1. We found that PMA significantly increased the invasive ability and the MMP-9 activity of THP-1 cells, as analyzed by matrix invasion assay and gelatin zymography, respectively. The increased expression of MMP-9 was demonstrated at both the RNA and protein levels by RT/real-time PCR and western blot analysis. These changes were markedly inhibited by cilostazol in a dose-dependent manner, which also could be observed when cAMP analog was used. On the contrary, the expression of TIMP-1, an inhibitor of MMP-9, was significantly upregulated by cilostazol dose dependently at both the RNA and protein levels. Reverse zymography further confirmed the increase of TIMP-1 activity after cilostazol treatment. The increase of TIMP-1 by cilostazol, however, was not cAMP-dependent. Cilostazol reduced the MMP-9 promoter activity and suppressed the nuclear translocation of NF-κB, indicating that the inhibitory effect of cilostazol is at the transcriptional level. In conclusion, the present study provides an additional mechanism underlying the anti-atherosclerotic effect of cilostazol by inhibiting the monocyte invasion and modulating the gene expressions of MMP-9 and TIMP-1 in monocytes upon differentiating to macrophages.

Aristolochic acid downregulates monocytic matrix metalloproteinase-9 by inhibiting nuclear factor-κB activation

Aristolochic acid (AA)-associated nephropathy was described as being characterized by a rapid progressive enhancement of interstitial renal fibrosis. Renal tissue fibrosis occurs because of an imbalance of extracellular matrix (ECM) accumulation and matrix metalloproteinase (MMP) activation. Much evidence indicates that inflammatory renal disease including monocyte and mesangial interactions is linked to the development and progression of renal remodeling. In this study, we found that AA showed concentration-dependent inhibition of tumor necrosis factor (TNF)-α-induced MMP-9 activation with an IC(50) value of 6.4±0.5μM in human monocytic THP-1 cells. A similar effect was also noted with different ratios of AAs (types I and II). However, AA had no inhibitory effect on the intact enzymatic activity of MMP-9 at a concentration of 20μM. On the other hand, the level of tissue inhibitor of metalloproteinase (TIMP)-1 was not induced by AA, but it suppressed TNF-α-induced MMP-9 protein and messenger RNA expressions. AA also significantly inhibited TNF-α-induced IκBα degradation. Furthermore, an electrophoretic mobility shift assay and a reported gene study, respectively, revealed that AA inhibited TNF-α-induced NF-κB translocation and activation. In addition, compared to other NF-κB inhibitors, AA exerted significant inhibition of MMP-9 activation and monocyte chemotactic protein-1-directed invasion. From these results, we concluded that AA, a natural compound, inhibits TNF-α-induced MMP-9 in human monocytic cells possibly through the NF-κB signal pathway. These results also imply that AA may be involved in alteration of matrix homeostasis during renal fibrosis in vivo.

Differential gene expression and translational approaches to identify biomarkers of interferon beta activity in multiple sclerosis

More than 16 years ago human interferon-β-1b (IFN-β-1β) was shown to be effective in the treatment of the relapsing-remitting form of multiple sclerosis (MS). Over time, IFN-β has been demonstrated to be both a safe and effective treatment. However, the mechanism of action of IFN-β in MS remains unknown. To better understand the mechanism of action of IFN-β, considerable effort has been made in transcriptional profiling of peripheral blood mononuclear cells collected from MS patients. IFN-β is known to induce a large number of genes that play an important role in regulating responses to viral infection, immune modulation, and cell proliferation. Identifying differentially induced genes that are linked to the beneficial effects observed during treatment is under active investigation. IFN biomarkers in MS patients have been proposed but have not been clearly confirmed in independent studies or consistently correlated with clinical measures of disease progression. Organizing single genes or gene signatures grouped according to molecular mechanisms meaningful in MS may help to link IFN activity measurements to clinical outcomes. In this review, IFN activity measurements will be discussed with a specific emphasis on what is known about differential gene expression and treatment effects in MS.

Regulatory effects of interferon-β on osteopontin and interleukin-17 expression in multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease characterized by autoimmune inflammation in the central nervous system. Despite over a decade of use of interferon-β (IFN-β) in the treatment of MS, its mechanisms of action are still not fully elucidated. New data now demonstrate that the 2 important proinflammatory cytokines involved in the pathogenesis of MS, osteopontin (OPN) and interleukin-17 (IL-17), are regulated by IFN-β. This review discusses the role of OPN and IL-17 in the development of MS and how the downregulation of the levels of OPN and interleukin-17 contributes to the therapeutic effects of IFN-β in MS.

Injury-induced type I IFN signaling regulates inflammatory responses in the central nervous system

Innate glial response is critical for the induction of inflammatory mediators and recruitment of leukocytes to sites of the injury in the CNS. We have examined the involvement of type I IFN signaling in the mouse hippocampus following sterile injury (transection of entorhinal afferents). Type I IFNs signal through a receptor (IFNAR), which involves activation of IFN regulatory factor (IRF)9, leading to the induction of IFN-stimulated genes including IRF7, that in turn enhances the induction of type I IFN. Axonal transection induced upregulation of IRF7 and IRF9 in hippocampus. Induction of IRF7 and IRF9 mRNAs was IFNAR dependent. Double-labeling immunofluorescence showed that IRF7 selectively was induced in Mac-1/CD11b(+) macrophages/microglia in hippocampus after axonal transection. IRF7 mRNA was also detected in microglia sorted by flow cytometry. Lack of type I IFN signaling resulted in increased leukocyte infiltration into the lesion-reactive hippocampus. Axonal lesion-induced CXCL10 gene expression was abrogated, whereas matrix metalloproteinase 9 mRNA was elevated in IFNAR-deficient mice. Our findings point to a role for type I IFN signaling in regulation of CNS response to sterile injury.

Minocycline differentially modulates macrophage mediated peripheral immune response following Japanese encephalitis virus infection

Japanese encephalitis virus (JEV) is a neurotropic flavivirus that is the causative agent of a major mosquito-borne encephalitis in the world. Evasion of peripheral immune system facilitates the entry of the virus into the central nervous system (CNS) where it causes extensive neuronal inflammatory damage that leads to death or severe neuropschychiatric sequel in survivors. It has been proposed that after entry into the body, the virus is carried into the CNS by peripheral immune cells that act as Trojan horses. In this study we investigate whether macrophages can be considered as such a Trojan horse. We also investigate the role of minocycline, a synthetic tetracycline, in such processes. Minocycline has been found to be broadly protective in neurological disease models featuring inflammation and cell death but there has been no report of it having any modulatory role in peripheral macrophage-mediated immune response against viral infection. Persistence of internalized virus within macrophages was visualized by immunofluorescent staining. Cytotoxicity assay revealed that there was no significant cell death after 24 h and 72 h infection with JEV. Proinflammatory cytokine levels were elevated in cells that were infected with JEV but it was abrogated following minocycline treatment. Reactive oxygen species level was also increased after JEV infection. Nitric oxide level was found to increase after 72 h post infection but remained unchanged after 24h. The cellular levels of signaling molecules such as PI3 kinase, phophoAkt and phospho p38MAP kinase were found to be altered after JEV infection and minocycline treatment. JEV infection also affected the VEGF-MMP pathway. Increased activity of MMP-9 was detected from JEV-infected macrophage culture supernatants after 72 h; minocycline treatment resulted in reduced activity. Thus it seems that minocycline dampens peripheral immune reactions by decreasing proinflammatory cytokine release from infected macrophages and the virus survives within macrophages long enough to be carried into the CNS, even though minocycline inhibits cell survival.

PEG minocycline-liposomes ameliorate CNS autoimmune disease

Background

Minocycline is an oral tetracycline derivative with good bioavailability in the central nervous system (CNS). Minocycline, a potent inhibitor of matrix metalloproteinase (MMP)-9, attenuates disease activity in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Potential adverse effects associated with long-term daily minocycline therapy in human patients are concerning. Here, we investigated whether less frequent treatment with long-circulating polyethylene glycol (PEG) minocycline liposomes are effective in treating EAE.

Findings

Performing in vitro time kinetic studies of PEG minocycline-liposomes in human peripheral blood mononuclear cells (PBMCs), we determined that PEG minocycline-liposome preparations stabilized with CaCl₂ are effective in diminishing MMP-9 activity. Intravenous injections of PEG minocycline-liposomes every five days were as effective in ameliorating clinical EAE as daily intraperitoneal injections of minocycline. Treatment of animals with PEG minocycline-liposomes significantly reduced the number of CNS-infiltrating leukocytes, and the overall expression of MMP-9 in the CNS. There was also a significant suppression of MMP-9 expression and proteolytic activity in splenocytes of treated animals, but not in CNS-infiltrating leukocytes. Thus, leukocytes gaining access to the brain and spinal cord require the same absolute amount of MMP-9 in all treatment groups, but minocycline decreases the absolute cell number.

Conclusions

Our data indicate that less frequent injections of PEG minocycline-liposomes are an effective alternative pharmacotherapy to daily minocycline injections for the treatment of CNS autoimmune diseases. Also, inhibition of MMP-9 remains a promising treatment target in EAE and patients with MS.

Pharmacological activation of the prostaglandin E2 receptor EP4 improves cardiac function after myocardial ischaemia/reperfusion injury

AIMS

Increased expression of several subtypes of prostaglandin E(2) receptors (EP1-4) has recently been described in clinical and experimental myocardial ischaemia/reperfusion (I/R) injury. However, their pathophysiological significance in I/R remains obscure. Thus, we determined whether the activation of the prostanoid receptor, EP4, suppresses myocardial I/R injury.

METHODS AND RESULTS

To analyse the role of EP4, we administered an EP4 selective agonist (EP4RAG, 1 or 3 mg/kg) or vehicle to rats with myocardial I/R injury. After 7 days of reperfusion, I/R rats exhibited left ventricular (LV) dilatation and contractile dysfunction with myocyte hypertrophy and interstitial fibrosis. EP4RAG significantly reduced infarction area/ischaemic myocardium (72.4 +/- 0.7 vs. 23.3 +/- 0.6%; P < 0.05) and improved LV contraction and dilatation compared with that of the vehicle. EP4RAG also attenuated the recruitment of inflammatory cells, especially macrophages, and interstitial fibrosis in hearts. Monocyte chemoattractant protein (MCP)-1 and other cytokines were increased in both non-ischaemic (area not at risk, ANAR) and ischaemic (area at risk, AAR) myocardium; however, western blot analysis and RNase protection assay showed that EP4RAG suppressed these changes. Gelatin zymography revealed EP4RAG significantly reduced matrix metalloproteinase-2 and -9 activities in both ANAR and AAR. Chemoattractant assay demonstrated that EP4RAG suppressed the migration of cytokine-stimulated macrophages and decreased the level of MCP-1 production in the supernatant (587.3 +/- 55.3 vs. 171.5 +/- 47.5 pg/mL; P < 0.05).

CONCLUSION

The data suggest that the EP4 agonist is effective for attenuation of I/R injury by suppressing MCP-1 and the infiltration of inflammatory cells, especially macrophages.

Ceramide inhibition of MMP-2 expression and human cancer bronchial cell invasiveness involve decreased histone acetylation

Ceramides have been proposed as potential therapeutic strategy with regard to their ability to induce cell death. We previously demonstrated that C2-ceramide generated apoptosis in bronchocarcinoma BZR cells. We here investigated whether ceramides also target other molecules involved in cell-cell or cell-matrix interactions during cancer progression. A SuperArray(R) analysis showed that ceramides modulate gene expression after 2 h. Among deregulated genes, we observed an inhibition of the transcript coding for the pro-metastatic enzyme MMP-2. The pharmacological inhibitor of caspases cascade, ZVAD-fmk, did not prevent C2-ceramide-induced down-regulation of MMP-2 ruling out apoptosis as a mediator of this event, whereas inhibition of oxidative stress using NAC confirmed a role for ROS. This effect of C2-ceramide was associated with changes in histone H3 acetylation. However, although histone deacetylase inhibitors are also currently under investigation for their anti-tumor activity, we demonstrated here that a combined treatment with trichostatin A abrogated both MMP-2 down-regulation and reduced invasive properties elicited by C2-ceramide alone. Hence, this study demonstrates that besides its apoptotic effect, C2-ceramide also exhibits anti-invasive properties, showing a dual beneficial effect against cancer progression, but casts some doubt on the use of HDAC inhibitors as combined treatment with drugs that trigger the ceramide pathway.

Type I interferons as anti-inflammatory mediators

The type I interferons (IFNs), IFN-alpha and IFN-beta, are cytokines that have antiviral, antiproliferative, and immunomodulatory activities. Data are now emerging that suggest that type I IFNs are also important mediators of anti-inflammatory responses. These findings, largely driven by studies to explain the beneficial effects of IFN-beta in the treatment of multiple sclerosis, an autoimmune disease of the central nervous system, offer a number of mechanisms for the anti-inflammatory properties of type I IFNs. Type I IFNs, through their ability to induce the immunosuppressive cytokine interleukin-10 (IL-10), mediate the inhibition of proinflammatory gene products. In addition, type I IFNs induce other immunosuppressive mediators such as suppressor of cytokine signaling-1 (SOCS-1) and tristetrapolin (TTP), which act by divergent mechanisms to restore homeostasis to the immune system. Furthermore, type I IFNs mediate anti-inflammatory and protective effects in a variety of autoimmune disease models such as experimental colitis, experimental allergic encephalomyelitis, experimental arthritis, and neonatal inflammation. Here, we discuss the molecular basis for the anti-inflammatory properties of type I IFNs and their therapeutic potential in autoimmune and inflammatory diseases.

Effect of immunomodulation with human interferon-beta on early functional recovery from experimental spinal cord injury

STUDY DESIGN

Electron and light microscopic changes, neutrophil infiltration, and lipid peroxidation in the spinal cord and early neurologic examination were studied in rats.

OBJECTIVE

To examine the effects of immunomodulator treatment with recombinant human interferon-beta after spinal cord contusion injury.

SUMMARY OF BACKGROUND DATA

Immunomodulator treatment with interferon-beta has been the subject of extensive studies, but mainly in relation to multiple sclerosis. Recently, it was reported that interferon-beta possessed significant neuroprotection after experimental transient ischemic stroke. However, to our knowledge, there have been no previous reports about the neuroprotective effect of interferon-beta after spinal cord injury.

METHODS

Rats were randomly allocated into 5 groups. Group 1 was control and after clinical examination, normal spinal cord samples were obtained. Group 2 was introduced 50 g/cm contusion injury. Group 3 was vehicle, immediately after trauma 1 mL of physiologic saline was injected. Group 4 was given 30 mg/kg methylprednisolone sodium succinate intraperitoneally immediately after trauma. Group 5 was given 1 x 10(7) IU interferon-beta immediately and 0.5 x 10(7) IU interferon-beta 4 hours after trauma. Animals were examined by inclined plane and Basso-Beattie-Bresnahan scale 24 hours after trauma. Spinal cord samples obtained following clinical evaluations. Neutrophil infiltration was evaluated by myeloperoxidase activity and lipid peroxidation was estimated by thiobarbituric acid test. Electron and light microscopic results were also performed to determine the effects of interferon-beta on tissue structure.

RESULTS

Interferon-beta treatment improved neurologic outcome, which was supported by decreased myeloperoxidase activity and lipid peroxidation. Electron and light microscopic results also showed preservation of tissue structure in the treatment group.

CONCLUSIONS

Immunomodulator treatment with interferon-beta possesses obvious neuroprotection after acute contusion injury to the rat spinal cord.

Matrix metalloproteinases, their production by monocytes and macrophages and their potential role in HIV-related diseases

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that are a subfamily of metzincins. Matrix metalloproteinases are responsible for much of the turnover of extra-cellular matrix components and are key to a wide range of processes including tissue remodeling and release of biological factors. Imbalance between the MMPs and endogenous tissue inhibitors of metalloproteinases (TIMPs) can result in dysregulation of many biologic processes and lead to the development of malignancy, cardiovascular disease, and autoimmune and inflammatory disorders. MMP production by monocyte/macrophages is dependent on the cell type, state of differentiation, and/or level of activation and whether they are infected, e.g., by HIV-1. MMP expression by HIV-1 infected monocytes and macrophages may alter cellular trafficking and contribute to HIV-associated pathology such as HIV-associated dementia (HAD). This review will provide a classification of the MMP super-family with particular reference to those produced by monocyte/macrophages, describe their regulation and function within the immune system, and indicate their possible roles in the pathogenesis of disease, including HIV-associated dementia.

Anti-inflammatory properties of Type I interferons

The notion that Type I interferons (interferon-alpha and -beta) possess anti-inflammatory potential is supported by data from clinical application in multiple sclerosis, by studies on cultured immune-competent cells and by investigation of experimental diseases in whole animals. These observations deserve the attention of virologists for their potential role in the pathogenesis and clinical management of virus infections.

Lipoic acid in multiple sclerosis: a pilot study

Lipoic acid (LA) is an antioxidant that suppresses and treats an animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis. The purpose of this study was to determine the pharmacokinetics (PK), tolerability and effects on matrix metalloproteinase-9 (MMP-9) and soluble intercellular adhesion molecule-1 (sICAMP-1) of oral LA in patients with MS. Thirty-seven MS subjects were randomly assigned to one of four groups: placebo, LA 600 mg twice a day, LA 1200 mg once a day and LA 1200 mg twice a day. Subjects took study capsules for 14 days. We found that subjects taking 1200 mg LA had substantially higher peak serum LA levels than those taking 600 mg and that peak levels varied considerably among subjects. We also found a significant negative correlation between peak serum LA levels and mean changes in serum MMP-9 levels (T = -0.263, P =0.04). There was a significant dose response relationship between LA and mean change in serum sICAM-1 levels (P =0.03). We conclude that oral LA is generally well tolerated and appears capable of reducing serum MMP-9 and sICAM-1 levels. LA may prove useful in treating MS by inhibiting MMP-9 activity and interfering with T-cell migration into the CNS.

Statins and their potential targets in multiple sclerosis therapy

Multiple sclerosis (MS) is a CNS-demyelinating disease characterised by relapsing and chronic neurological impairment. While traditionally CNS autoantigen-specific CD4(+) T cells have been considered the culprits in the initial phase of the disease, recent observations have altered this concept. It is now recognised that other T lymphocyte subclasses can initiate CNS demyelination. In addition, other cell types and molecules may play an important role in MS pathogenesis. There is overwhelming evidence that MS is a dynamic process, in which recurrent episodes of blood-brain barrier disruption and CNS inflammation play a crucial role in early disease stages, leading eventually to the largely irreversible changes of demyelination, gliosis and axonal degeneration. These observations may have important therapeutic implications. Within the last ten years, several medications have been approved for MS treatment. These agents, all of which are given parenterally, are only partially effective and are often associated with adverse effects and potential toxicities. The number and different types of medications used for MS are likely to increase in the near future, as several novel therapies are currently tested in clinical trials. 3-hydroxy-3-methyglutaryl coenzyme A reductase inhibitors, 'statins', are cholesterol-lowering drugs that are given orally, are safe and have biological effects independent of their cholesterol-reducing properties. Recent reports have shown that statins have anti-inflammatory and neuroprotective properties that may be beneficial in the treatment of MS. This article will outline experimental evidence that suggests potential clinical benefits of statins for MS patients.

The potential use of MMP inhibitors to treat CNS diseases

The matrix metalloproteinases (MMPs) are considered to be the physiological mediators of extracellular matrix remodelling. MMPs are involved in a variety of functions and in the nervous system, these include angiogenesis and the extension of neuronal growth cones during development. However, it has become increasingly evident that the aberrant expression of MMPs in the nervous system contributes to diseases that include among others, multiple sclerosis, malignant gliomas, Alzheimer's disease and stroke. This review highlights the evidence that MMPs are involved in diseases of the nervous system, and provides information for the potential beneficial use of MMP inhibitors in NS disorders. However, the application of MMP inhibitors to treat CNS diseases must be balanced carefully against the beneficial roles normally played by MMPs in CNS physiology or recovery.

? lipoic acid inhibits human T-cell migration: Implications for multiple sclerosis

We have demonstrated previously the ability of the antioxidant alpha lipoic acid (ALA) to suppress and treat a model of multiple sclerosis (MS), relapsing experimental autoimmune encephalomyelitis (EAE). We describe the effects of ALA and its reduced form, dihydrolipoic acid (DHLA), on the transmigration of human Jurkat T cells across a fibronectin barrier in a transwell system. ALA and DHLA inhibited migration of Jurkat cells in a dose-dependent fashion by 16-75%. ALA and DHLA reduced matrix metalloproteinase-9 (MMP-9) activity by 18-90% in Jurkat cell supernatants. GM6001, a synthetic inhibitor of MMP, reduced Jurkat cell migration, but not as effectively as ALA and DHLA did. Both ALA and DHLA downmodulated the surface expression of the alpha4beta1 integrin (very late activation-4 antigen; VLA-4), which binds fibronectin and its endothelial cell ligand vascular cell adhesion molecule-1 (VCAM-1). Moreover, ALA, but not DHLA, reduced MMP-9-specific mRNA and extracellular MMP-9 from Jurkat cells and their culture supernatants as detected by relative reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. ALA and DHLA inhibited Jurkat cell migration and have different mechanisms for inhibiting MMP-9 activity. These data, coupled with its ability to treat relapsing EAE, suggest that ALA warrants investigation as a therapy for MS.

Statins as potential therapeutic agents in multiple sclerosis

3-Hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (ie, statins) are oral cholesterol-lowering drugs. Statins are well tolerated and have an excellent safety record. These agents competitively inhibit HMG CoA reductase, which is the enzyme that catalyzes the conversion of HMG CoA to L-mevalonate. Although L-mevalonate is a key intermediate in cholesterol synthesis, several of its metabolites are involved in post-translational modification of specific proteins involved in cell proliferation and differentiation. Thus, independent of their cholesterol-reducing properties, statins have important pleiotropic biologic effects. Recent reports indicate that statins have anti-inflammatory and neuroprotective properties. Whether statins will be of clinical benefit for patients with multiple sclerosis and other neurodegenerative diseases of the central nervous system will only be known after they are evaluated in prospective randomized clinical trials.

Functional roles and therapeutic targeting of gelatinase B and chemokines in multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the CNS of unknown cause. Pathogenetic mechanisms, such as chemotaxis, subsequent activation of autoreactive lymphocytes, and skewing of the extracellular proteinase balance, are targets for new therapies. Matrix metalloproteinase gelatinase B (MMP-9) is upregulated in MS and was recently shown to degrade interferon beta, one of the drugs used to treat MS. Consequently, the effect of endogenously produced interferon beta or parenterally given interferon beta may be increased by gelatinase B inhibitors. Blockage of chemotaxis or cell adhesion molecule engagement, and inhibition of hydroxymethyl-glutaryl-coenzyme-A reductase to lower expression of gelatinase B, may become effective treatments of MS, alone or in combination with interferon beta. This may allow interferon beta to be used at lower doses and prevent side-effects.

Interferon-beta blocks infiltration of inflammatory cells and reduces infarct volume after ischemic stroke in the rat

The inflammatory response that exacerbates cerebral injury after ischemia is an attractive therapeutic target: it progresses over days and strongly contributes to worsening of the neurologic outcome. The authors show that, after transient ischemic injury to the rat brain, systemic application of interferon-beta (IFN-beta), a cytokine with antiinflammatory properties, attenuated the development of brain infarction. Serial magnetic resonance imaging (MRI) showed that IFN-beta treatment reduced lesion volume on diffusion-weighted MRI by 70% (P < 0.01) at 1 day after stroke. IFN-beta attenuated the leakage of contrast agent through the blood-brain barrier (P < 0.005), indicating a better-preserved blood-brain barrier integrity. Both control and IFN-beta-treated animals showed a similar degree of relative hyperperfusion of the lesioned hemisphere, indicating that neuroprotection by IFN-beta was not mediated by improved cerebral perfusion as assessed 24 hours after stroke onset. IFN-beta treatment resulted in an 85% reduction (P < 0.0001) in infarct volume 3 weeks later, as determined from T2-weighted MRI and confirmed by histology. This effect was achieved even when treatment was started 6 hours after stroke onset. Quantitative immunohistochemistry at 24 hours after stroke onset showed that IFN-beta almost completely prevented the infiltration of neutrophils and monocytes into the brain. Gelatinase zymography showed that this effect was associated with a decrease in matrix metalloproteinase-9 expression. In conclusion, treatment with the antiinflammatory cytokine IFN-beta affords significant neuroprotection against ischemia/reperfusion injury, and within a relatively long treatment window. Because IFN-beta has been approved for clinical use, it may be rapidly tested in a clinical trial for its efficacy against human stroke.

Interferon-beta prevents cytokine-induced neutrophil infiltration and attenuates blood-brain barrier disruption

Inflammation can contribute to brain injury, such as that resulting from ischemia or trauma. The authors have previously shown that the cytokine interferon-beta (IFN-beta) affords protection against ischemic brain injury, which was associated with a diminished infiltration of neutrophils and a reduction in blood-brain barrier (BBB) disruption. The goal of the current study was to directly assess the effects of IFN-beta on neutrophil infiltration, with the use of an in vivo assay of neutrophil infiltration with relevance to ischemic brain injury. Intrastriatal injection of recombinant rat cytokine-induced neutrophil chemoattractant-1, a member of the interleukin-8 family (1 microg in 1 microl), triggered massive infiltration of neutrophils and extensive BBB disruption 6 hours later, as measured using immunofluorescence microscopy and magnetic resonance imaging in the rat, respectively. Depleting the animals of neutrophils before interleukin-8 injection prevented BBB disruption. Treatment with IFN-beta (5 x 106 U/kg) almost completely prevented neutrophil infiltration and attenuated BBB damage. Gelatinase zymography showed matrix metalloproteinase-9 expression in the ipsilateral striatum after interleukin-8 injection. Both neutrophil depletion and IFN-beta treatment downregulated matrix metalloproteinase-9. IFN-beta has already been approved for human use as a treatment for the chronic inflammatory disorder multiple sclerosis. The potential value of IFN-beta as a treatment that can attenuate acute brain inflammation is considered.

Chemokines and matrix metalloproteinase-9 in leukocyte recruitment to the central nervous system

Chemokines and matrix metalloproteinases (MMPs) play key roles in leukocyte migration across the blood-brain barrier (BBB) in infectious and inflammatory diseases, including multiple sclerosis (MS). In MS some chemokine receptors are expressed by an increased percentage of T cells in blood, the CSF concentration of chemokine ligands for these receptors is increased, and there is accumulation of T cells expressing relevant chemokine receptors in CSF and in the CNS parenchyma. Chemokine receptor expression patterns appear to reflect disease activity and disease stage in MS. MMPs are constitutively expressed or induced by proinflammatory cytokines and chemokines in leukocytes and CNS-resident cells. Several MMPs are expressed in MS plaques, and the CSF concentration of MMP-9 is increased in MS. The CSF concentration of MMP-9 may reflect disease activity in MS, and the CSF concentration of MMP-9 is higher in patients carrying the MS-associated HLA type DRB1 1501. We review how chemokines and MMP-9 may be involved in the pathogenesis of MS by controlling leukocyte migration between different functional compartments. Measuring expression of these molecules may find use as surrogate markers of disease activity in MS, and interfering with their function holds promise as a novel therapeutic strategy in MS.

Adhesion molecules and matrix metalloproteinases in Multiple Sclerosis: effects induced by Interferon-beta

In Multiple Sclerosis (MS) pathology, early inflammation involves leukocyte migration across the blood-brain barrier (BBB) within the central nervous system. In this process, adhesion molecules (AMs), both membrane-bound and soluble-circulating forms, and matrix metalloproteinases (MMPs) certainly play a regulatory role. In MS, recombinant Interferon-beta (rIFNbeta) is effective in reducing gadolinium contrast-enhancing lesions on magnetic resonance imaging and this suggests that it may reduce BBB damage or even restore its integrity by different mechanisms that include interference with both AM and MMP pathways. This review will highlight the effects induced by rIFNbeta, both in vitro and in vivo, on cell-bound and soluble forms of AMs and on MMPs.

IFN-beta gene deletion leads to augmented and chronic demyelinating experimental autoimmune encephalomyelitis

Since the basic mechanisms behind the beneficial effects of IFN-beta in multiple sclerosis (MS) patients are still obscure, here we have investigated the effects of IFN-beta gene disruption on the commonly used animal model for MS, experimental autoimmune encephalomyelitis (EAE). We show that IFN-beta knockout (KO) mice are more susceptible to EAE than their wild-type (wt) littermates; they develop more severe and chronic neurological symptoms with more extensive CNS inflammation and demyelination. However, there was no discrepancy observed between wt and KO mice regarding the capacity of T cells to proliferate or produce IFN-gamma in response to recall Ag. Consequently, we addressed the effect of IFN-beta on encephalitogenic T cell development and the disease initiation phase by passive transfer of autoreactive T cells from KO or wt littermates to both groups of mice. Interestingly, IFN-beta KO mice acquired a higher incidence and augmented EAE regardless of the source of T cells. This shows that the anti-inflammatory effect of endogenous IFN-beta is predominantly exerted on the effector phase of the disease. Histopathological investigations of CNS in the effector phase revealed an extensive microglia activation and TNF-alpha production in IFN-beta KO mice; this was virtually absent in wt littermates. This coincided with an increase in effector functions of T cells in IFN-beta KO mice, as measured by IFN-gamma and IL-4 production. We suggest that lack of endogenous IFN-beta in CNS leads to augmented microglia activation, resulting in a sustained inflammation, cytokine production, and tissue damage with consequent chronic neurological deficits.

Monocyte chemoattractant protein 1 and chemokine receptor CCR2 productions in Guillain-Barré syndrome and experimental autoimmune neuritis

Infiltration of activated lymphocytes and monocytes is a key phenomenon in the pathogenesis of Guillain-Barré syndrome (GBS) and experimental autoimmune neuritis (EAN). To investigate the role of chemokines, we determined the blood and nerve tissue expression of monocyte chemoattractant protein 1 (MCP-1), a major chemoattractant of monocytes and activated lymphocytes, and its receptor CCR2 in GBS and EAN. MCP-1 circulating levels (ng/ml) in GBS were increased at the time of progression, peaked at the time of plateau and normalized with recovery. MCP-1 circulating levels were the highest in the most disabled patients. The number of circulating CCR2 positive cells was lower in patients with GBS than in healthy subjects (p<0.004). In GBS, MCP-1 expression was observed in epineurial and endoneurial vessels, on infiltrating cells, Schwann cells and in the endoneurial extracellular matrix. Some CCR2 positive cells were observed in nerve biopsies of GBS patients. In EAN, a slight positivity for MCP-1 was observed in the sciatic nerve. There was no circulating CCR2 positive cells. However, at the time of plateau, a conspicuous infiltration of CCR2 positive cells was observed in the sciatic nerve that was no longer observed at the time of recovery. These results suggest that MCP-1 and CCR2 may participate to the recruitment of circulating mononuclear cells in nerve tissue in EAN and GBS.

Cellular immunity and Chlamydia genital infection: induction, recruitment, and effector mechanisms

Chlamydia trachomatis is one of the major causes of bacterial sexually transmitted disease worldwide. The initial infection of endocervical epithelium in females is asymptomatic and commonly ascends to fallopian tubes when left untreated. Immunity to Chlamydia develops after infection and appears to provide short-term protection. Consequently, a significant rate of reinfection occurs among sexually active individuals, which can result in reproductive disability. T helper type 1 responses are implicated in providing protective immunity but may also contribute to tubal infertility. The purpose of this chapter is to review the factors that regulate the induction and recruitment of protective cellular immune responses within the local genital mucosa. An understanding of these events is important for the design of a protective vaccine and control of immunopathologic reactions.

Upregulation of matrix metalloproteinase-9 in murine 5T33 multiple myeloma cells by interaction with bone marrow endothelial cells

MM is a B-cell malignancy mainly characterized by monoclonal expansion of plasma cells in the BM, presence of paraprotein in serum and occurrence of osteolytic bone lesions. MMPs are a family of proteolytic enzymes that can contribute to cancer growth, invasion, angiogenesis, bone degradation and other processes important in the pathogenesis of MM. We investigated MMP-9 production in the 5T33MM murine model. Expression of MMP-9 protein in supernatant and cell extracts was analyzed by gelatin zymography. The in vitro, stroma-independent variant 5T33MMvt showed no protein expression of MMP-9 in contrast to in vivo growing MM cells, 5T33MMvv. However, when 5T33MMvt cells were injected into naive mice and isolated after tumor take (5T33MMvt-vv), they secreted a significant amount of MMP-9. These results were confirmed by specific staining of cytospins with an anti-MMP-9 antibody. The MMP-9 production by 5T33MMvt-vv cells disappeared when the cells were recultured in vitro. These data demonstrated that upregulation of MMP-9 occurs in vivo and that this process is dependent on the microenvironment. Cocultures of 5T33MMvt cells with STR10 BMECs induced MMP-9 in MM cells, as determined by both gelatin zymography and flow-cytometric analysis. In conclusion, our results demonstrate that MMP-9 production by MM cells is upregulated in vivo by the interaction of MM cells with BMECs.

Alpha lipoic acid inhibits T cell migration into the spinal cord and suppresses and treats experimental autoimmune encephalomyelitis

Oxidative injury may be important to the pathogenesis of multiple sclerosis (MS). We tested the antioxidant alpha lipoic acid (ALA) in an experimental murine model of MS, experimental autoimmune encephalomyelitis (EAE). ALA was administered to SJL mice 7 days after immunization with proteolipid protein (PLP) 139-151 peptide. Mice that received 5-100 mg/kg/day of ALA had dose-dependent reductions in their 10-Day Cumulative Disease Scores (10-Day CDS) by 23-100%. Minimal inflammation, demyelination and axonal loss occurred in the spinal cords (SC) of ALA-suppressed mice, and there was a marked reduction in CD3+ T cells and CD11b+ monocyte/macrophage cells within the SC. Mice treated with ALA (100 mg/kg/day) commencing on the first day of clinical EAE had a significant reduction in 10-Day CDS. SC of ALA-treated mice had reduced demyelination and axonal loss and a rapid reduction in CD3+ T cells. In vitro, ALA and its reduced form, dihydrolipoic acid, inhibited the activity of matrix metalloproteinase-9 (MMP-9) in a dose-dependent fashion. ALA is highly effective at suppressing and treating EAE and does so by inhibiting T cell trafficking into the SC, perhaps by acting as a matrix metalloproteinase inhibitor.

Modulation of monocytes matrix metalloproteinase-2, MT1-MMP and TIMP-2 by interferon-gamma and -beta: implications to multiple sclerosis

Recent findings have implicated the activity of matrix metalloproteinases (MMPs) in the pathogenesis of multiple sclerosis (MS), while in vivo interferon (IFN)-beta treatment was demonstrated to suppress MMPs. In the present study, the effects mediated by IFN-gamma and IFN-beta on the mRNA and protein expression of MMP-2, its physiological activator, MT1-MMP and its endogenous inhibitor, TIMP-2, by monocytes were evaluated in vitro. The results point to the significance of IFNs in modulating MMPs/tissue inhibitors of MMPs (TIMPs) expression, and support the possibility that the therapeutic effects of IFN-beta may be, in part, due to induction of a shift from "pro-" to "anti-proteolytic" pattern of MMPs and TIMPs expression.

Approved and future pharmacotherapy for multiple sclerosis

BACKGROUND

Pharmacotherapy for relapsing-remitting multiple sclerosis (MS) advanced with the demonstration that interferon beta and glatiramer acetate improve the clinical course of this disease. Mitoxantrone is the first drug approved by the Food and Drug Administration for treatment of secondary progressive MS. Despite this progress, the agents presently available are only partially effective, are difficult to administer, and may have significant side effects. Several orally administered immunomodulatory agents are presently being evaluated for treatment of MS. One class of drugs, HMG CoA inhibitors (statins), is safe and well-tolerated and could become another mainstay of MS therapy.

REVIEW SUMMARY

This article reviews the clinical evidence for approved MS therapies and discusses their mechanisms of action. Furthermore, the clinical and laboratory data suggesting a potential role for statins in MS therapy are discussed.

CONCLUSIONS

Although treatment with interferon beta, glatiramer acetate, and mitoxantrone, the approved therapies, provide important treatment options for patients with relapsing-remitting MS and secondary progressive MS, the potential benefits of other medications, including statins, should be explored in controlled clinical trials.

Expression and modulation of IFN-gamma-inducible chemokines (IP-10, Mig, and I-TAC) in human brain endothelium and astrocytes: possible relevance for the immune invasion of the central nervous system and the pathogenesis of multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS) mediated by blood-derived immune cells invading the CNS. This invasion could be determined by chemokines, and their role within the MS-affected brain is still poorly defined. We investigated the expression by RT-PCR and protein release by ELISA of the interferon-gamma (IFN-gamma)-inducible chemokines in human brain microvascular endothelial cells (HBMECs) and astrocytes. The monokine induced by IFN-gamma (Mig) behaves as a homing chemokine constitutively expressed in HBMECs and astrocytes, whereas the IFN-gamma-inducible 10-kDa protein (IP-10) and IFN-inducible T cell alpha-chemoattractant (I-TAC) are induced only after inflammatory stimuli. The biologic activity of IFN-gamma-inducible chemokines from an endothelial source was analyzed, and the transendothelial migration of activated lymphocytes was partly antagonized by specific antibodies, especially anti-Mig antibody. Our data highlight the capability of cells of the CNS to activate the chemoattractant machinery in a proinflammatory environment and in MS.

Interferon-beta directly influences monocyte infiltration into the central nervous system

Interferon-beta (IFN-beta) has beneficial effects on the clinical symptoms of multiple sclerosis (MS) patients, but its exact mechanism of action is yet unknown. We here suggest that IFN-beta directly modulates inflammatory events at the level of cerebral endothelium. IFN-beta treatment resulted in a marked reduction of perivascular infiltrates in acute experimental allergic encephalomyelitis (EAE), the rat model for MS, which was coupled to a major decrease in the expression of the adhesion molecules ICAM-1 and VCAM-1 on brain capillaries. In vitro, IFN-beta reduced the mRNA levels and protein expression of adhesion molecules of brain endothelial cell cultures and diminished monocyte transendothelial migration. Monocyte adhesion and subsequent migration was found to be predominantly regulated by VCAM-1. These data indicate that IFN-beta exerts direct antiinflammatory effects on brain endothelial cells thereby contributing to reduced lesion formation as observed in MS patients.