Carmen Espejo

Altered inflammatory response and increased neurodegeneration in metallothionein I+II deficient mice during experimental autoimmune encephalomyelitis

Metallothionein-I+II (MT-I+II) are antioxidant, neuroprotective proteins, and in this report we have examined their roles during experimental autoimmune encephalomyelitis (EAE) by comparing MT-I+II-knock-out (MTKO) and wild-type mice. We herewith show that EAE susceptibility is higher in MTKO mice relatively to wild-type mice, and that the inflammatory responses elicited by EAE in the central nervous system (CNS) are significantly altered by MT-I+II deficiency. Thus, during EAE the MTKO mice showed increased macrophage and T-lymphocytes infiltration in the CNS, while their reactive astrogliosis was significantly decreased. In addition, the expression of the proinflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha elicited by EAE was further increased in the MTKO mice, and oxidative stress and apoptosis were also significantly increased in MTKO mice compared to normal mice. The present results strongly suggest that MT-I+II are major factors involved in the inflammatory response of the CNS during EAE and that they play a neuroprotective role in this scenario.

Expression of chemokine receptors in the different clinical forms of multiple sclerosis

Chemokines and their receptors are important in the trafficking of peripheral leukocytes into the central nervous system, a major event in the pathogenesis of multiple sclerosis (MS). Evidence based on clinical, pathological and magnetic resonance imaging grounds supports some divergence between forms of MS with relapses [relapsing-remitting (RR) and secondary progressive (SP)] and the primary progressive (PP) form. To elucidate whether different pathogenic mechanisms are involved in PPMS, we compared membrane expression of a group of CC and CXC chemokine receptors (CCR1, CCR5, CXCR3, CXCR4) in peripheral blood of 68 MS patients (25 PPMS, 23 SPMS and 20 RRMS) and 26 healthy controls. We found a significant increase in surface expression of CCR5 in CD4+, CD8+, CD19+ and CD14+ cells as well as an increased percentage of CXCR3 and CXCR4 in CD14+ cells in MS patients compared to controls. Increased levels of CXCL10 (IP-10) and CCL5 (RANTES) in cerebrospinal fluid were also observed in a subgroup of MS patients. These results support that chemokines and their receptors are involved in the pathogenesis of MS. However, a pattern of chemokine-chemokine receptor expression characteristic of each clinical form of the disease failed to be observed.

Differential expression of metallothioneins in the CNS of mice with experimental autoimmune encephalomyelitis

Multiple sclerosis is an inflammatory, demyelinating disease of the CNS. Metallothioneins-I+II are antioxidant proteins induced in the CNS by immobilisation stress, trauma or degenerative diseases which have been postulated to play a neuroprotective role, while the CNS isoform metallothionein-III has been related to Alzheimers disease. We have analysed metallothioneins-I-III expression in the CNS of mice with experimental autoimmune encephalomyelitis. Moreover, we have examined the putative role of interferon-gamma, a pro-inflammatory cytokine, in the control of metallothioneins expression during experimental autoimmune encephalomyelitis in interferon-gamma receptor knockout mice with two different genetic backgrounds: 129/Sv and C57BL/6x129/Sv. Mice with experimental autoimmune encephalomyelitis showed a significant induction of metallothioneins-I+II in the spinal cord white matter, and to a lower extent in the brain. Interferon-gamma receptor knockout mice suffered from a more severe experimental autoimmune encephalomyelitis, and interestingly showed a higher metallothioneins-I+II induction in both white and grey matter of the spinal cord and in the brain. In contrast to the metallothioneins-I+II isoforms, metallothionein-III expression remained essentially unaltered during experimental autoimmune encephalomyelitis; interferon-gamma receptor knockout mice showed an altered metallothionein-III expression (a slight increase in the spinal cord white matter) only in the C57BL/6x129/Sv background. Metallothioneins-I+II proteins were prominent in areas of induced cellular infiltrates. Reactive astrocytes and activated monocytes/macrophages were the sources of metallothioneins-I+II proteins. From these results we suggest that metallothioneins-I+II but not metallothionein-III may play an important role during experimental autoimmune encephalomyelitis, and indicate that the pro-inflammatory cytokine interferon-gamma is unlikely an important factor in this response.

Increased demyelination and axonal damage in metallothionein I+II-deficient mice during experimental autoimmune encephalomyelitis

Abstract. Metallothioneins I+II (MT-I+II) are antioxidant, neuroprotective factors. We previously showed that MT-I+II deficiency during experimental autoimmune encephalomyelitis (EAE) leads to increased disease incidence and clinical symptoms. Moreover, the inflammatory response of macrophages and T cells, oxidative stress, and apoptotic cell death during EAE were increased by MT-I+II deficiency. We now show for the first time that demyelination and axonal damage are significantly increased in MT-I+II deficient mice during EAE. Furthermore, oligodendroglial regeneration, growth cone formation, and tissue repair including expression of trophic factors were significantly reduced in MT-I+II-deficient mice during EAE. Accordingly, MT-I+II have protective and regenerative roles in the brain.

Treatment with methylprednisolone in relapses of multiple sclerosis patients: immunological evidence of immediate and short‐term but not long‐lasting effects

Relapses of multiple sclerosis (MS) are treated commonly with high‐dose intravenous methylprednisolone (MP) given over a period of 3–5 days. The mechanisms responsible for the beneficial effects of MP in attacks are not clearly established. It is also controversial whether this treatment may have a long‐term effect. Here, peripheral blood samples from relapsing–remitting MS patients in acute relapse were analysed by flow cytometry just before steroid treatment and at different time points after initiation of the therapy. We observed an immediate (day 3) decrease in the percentage of CD4+ lymphocytes, with a relative increase in the memory (CD4+CD45R0+) subpopulation. A longer standing effect of MP on IFN‐γ production, CD54, CCR5, CXCR3 and CD95 (Fas) expression was also observed on CD4+ cells after 1 month of treatment initiation. Six months after the therapy, during clinical remission, no changes due to ivMP therapy were detected. These results support that MP treatment of relapses induces immediate post‐treatment and short‐term effects on the immune system that could partly account for the clinical and radiological improvement observed in MS patients. However, no conclussion can be drawn as to a possible long‐term or even intermediate influence of ivMP treatment on the course of the disease.

Lipid‐specific immunoglobulin M bands in cerebrospinal fluid are associated with a reduced risk of developing progressive multifocal leukoencephalopathy during treatment with natalizumab

Progressive multifocal leukoencephalopathy (PML) is a serious side effect associated with natalizumab treatment in multiple sclerosis (MS). PML risk increases in individuals seropositive for anti–John Cunningham virus (JC) antibodies, with prolonged duration of natalizumab treatment, and with prior exposure to immunosuppressants. We explored whether the presence of lipid‐specific immunoglobulin M oligoclonal bands in cerebrospinal fluid (CSF; IgM bands), a recognized marker of highly inflammatory MS, may identify individuals better able to counteract the potential immunosuppressive effect of natalizumab and hence be associated with a reduced risk of developing PML.

Expression of metallothionein-I, -II, and -III in Alzheimer disease and animal models of neuroinflammation

In recent years it has become increasingly clear that the metallothionein (MT) family of proteins is important in neurobiology. MT-I and MT-II are normally dramatically up-regulated by neuroinflammation. Results for MT-III are less clear. MTs could also be relevant in human neuropathology. In Alzheimer disease (AD), a major neurodegenerative disease, clear signs of inflammation and oxidative stress were detected associated with amyloid plaques. Furthermore, the number of cells expressing apoptotic markers was also significantly increased in these plaques. As expected, MT-I and MT-II immunostaining was dramatically increased in cells surrounding the plaques, consistent with astrocytosis and microgliosis, as well as the increased oxidative stress elicited by the amyloid deposits. MT-III, In contrast, remained essentially unaltered, which agrees with some but not all studies, of AD. In situ hybridization results in a transgenic mouse model of AD amyloid deposits, the Tg2576 mouse, which expresses human Aβ precursor protein harboring the Swedish K670N/M671L mutations, are in accordance with results in human brains. Overall, these and other studies strongly suggest specific roles for MT-I, MT-II, and MT-III in brain physiology.

Changes in matrix metalloproteinases and their inhibitors during interferon-beta treatment in multiple sclerosis

Matrix metalloproteinases (MMPs) and tissue inhibitors (TIMPs) play a key role in the pathogenesis of multiple sclerosis (MS) and have been proposed as biomarkers of response to therapy. We investigated serum levels of several MMPs and TIMPs in 43 relapsing-remitting MS (RRMS) patients undergoing interferon-beta (IFN-b) treatment and classified as responders and non-responders based on clinical criteria. Levels of MMP-2, MMP-7, MMP-9, TIMP-1 and TIMP-2 were determined by ELISA before treatment and after 3, 6, 12, and 24 months of therapy. Neutralizing antibodies were determined by the myxovirus A induction bioassay. Treatment with IFN-b induced changes in levels of MMP-9 and TIMP-1. In contrast to non-responders, IFN-b resulted in an early and sustained increase in TIMP-1 levels in MS patients who showed clinical response to IFN-b. The early and sustained increase in TIMP-1 levels could be a marker of the response to IFN-b during the first 2 years of treatment.

Metallothionein expression in the central nervous system of multiple sclerosis patients.

Abstract: Multiple sclerosis (MS) is a major chronic demyelinating and inflammatory disease of the central nervous system (CNS) in which oxidative stress likely plays a pathogenic role in the development of myelin and neuronal damage. Metallothioneins (MTs) are antioxidant proteins induced in the CNS by tissue injury, stress and some neurodegenerative diseases, which have been postulated to play a neuroprotective role. In fact, MT-I+II-deficient mice are more susceptible to developing experimental autoimmune encephalomyelitis (EAE), and treatment of Lewis rats with Zn-MT-II reduces EAE severity. We show here that, as in EAE, MT-I+II proteins were expressed in brain lesions of MS patients. Cells expressing MT-I+II were mainly astrocytes and activated monocytes/macrophages. Interestingly, the levels of MT-I+II were slightly increased in the inactive MS lesions in comparison with the active lesions, suggesting that MTs may be important in disease remission.

Heat Shock Protein 70: Roles in Multiple Sclerosis

Heat shock proteins (HSP) have long been considered intracellular chaperones that possess housekeeping and cytoprotective functions. Consequently, HSP overexpression was proposed as a potential therapy for neurodegenerative diseases characterized by the accumulation or aggregation of abnormal proteins. Recently, the discovery that cells release HSP with the capacity to trigger proinflammatory as well as immunoregulatory responses has focused attention on investigating the role of HSP in chronic inflammatory autoimmune diseases such as multiple sclerosis (MS). To date, the most relevant HSP is the inducible Hsp70, which exhibits both cytoprotectant and immunoregulatory functions. Several studies have presented contradictory evidence concerning the involvement of Hsp70 in MS or experimental autoimmune encephalomyelitis (EAE), the MS animal model. In this review, we dissect the functions of Hsp70 and discuss the controversial data concerning the role of Hsp70 in MS and EAE.