Jacek Losy

Chemokines and chemokine receptors in multiple sclerosis. Potential targets for new therapies.

Multiple sclerosis (MS) is a chronic demyelinating disease of the human central nervous system of a still unknown etiology. The autoimmune inflammatory process is believed to be essential for the development of the disease. Several different studies have shown that chemokines and chemokine receptors are involved in the pathogenesis of MS. Chemokines can mediate the trafficking of immune cells across the blood–brain barrier, and regulate their transfer to lesion sites. Chemokines were detected in actively demyelinating lesions and were found to be elevated in the cerebrospinal fluid of patients with MS during relapse. Different pairs of chemokine receptors and their ligands seem to play a pathogenic role in MS (e.g., CXCR3 and CXCL9, CXCL10; CCR1 and CCL3, CCL4, CCL5; CCR2 and CCL2; CCR5 and CCL3, CCL4, CCL5). Interfering with the chemokine system may be an effective therapeutic approach in MS. In this review we briefly summarize the results of the previous studies and identify the most important findings in the field.

Early TNF‐α levels correlate with ischaemic stroke severity

Objectives– The study aimed to evaluate the levels of an important proinflammatory cytokine tumour necrosis factor‐α (TNF‐α) in cerebrospinal fluid (CSF) and serum in acute stroke and to study the relation between those and the neurological stroke severity and functional disability. Material and methods– The investigations comprised 23 ischaemic stroke patients. CSF and blood samples were obtained 24 h after the onset of stroke, and stored until analysis. Patients were examined according to Scandinavian Stroke Scale (SSS) and to Barthel Index (BI). Results– The patients displayed statistically significant high levels of TNF‐α in CSF and sera within the first 24 h of stroke. These correlated significantly with SSS and BI scores calculated within the same interval, and 1 and 2 weeks later. Conclusion– Our results suggest the involvement of TNF‐α in mechanisms of early stroke‐induced inflammation and a predictive value of the initial TNF‐α levels for the outcome of stroke.

Tumour necrosis factor-alpha is increased in the cerebrospinal fluid and serum of ischaemic stroke patients and correlates with the volume of evolving brain infarct

A growing body of evidence suggests the involvement of inflammatory mediators, including cytokines, in the development of ischaemic brain lesions. The aim of the present study was to investigate whether tumour necrosis factor-alpha (TNF-alpha), the proinflammatory cytokine, contributes to early pathophysiological mechanisms leading to brain damage as a consequence of acute stroke. We have studied TNF-alpha levels in cerebrospinal fluid (CSF) and serum in 23 stroke patients within the first 24 hours after ischaemic stroke, confirmed by computerized tomography of the brain (CT). The control group consisted of 15 patients with the diagnosis of tension headache and neurasthenia. In stroke patients the levels of TNF-alpha both in CSF and serum were significantly higher in comparison with the control group. The positive correlation between the levels of TNF-alpha in CSF and serum of the studied patients has been observed. Furthermore, a positive correlation between both TNF-alpha levels in CSF and serum and the volume of evolving brain infarct have been shown.

IL-18 in patients with multiple sclerosis.

IL‐18 is a cytokine which plays an important role in Th‐1 response through its ability to induce IFN‐gamma production in T cells and NK cells. The purpose of the study was to measure IL‐18 levels in serum and CSF of 21 patients with the relapsing–remitting form of MS, 9 with active gadolinium enhancing lesions in MRI and 12 without enhancing lesions, and to compare results with control group consisting of 11 patients with diagnosis of neurasthenia and tension headache. IL‐18 concentration in the CSF and sera was measured by ELISA. We found a highly significant increase of both IL‐18 CSF and serum levels in MS patients in comparison with the control group. In patients with active MRI lesions the levels of IL‐18 in CSF and serum were significantly higher in comparison with the levels found in patients without enhancing lesions. The results suggest involvement of IL‐18 in immunopathogenesis of MS especially in the active stages of the disease.

Increased serum levels of soluble PECAM-1 in multiple sclerosis patients with brain gadolinium-enhancing lesions

Platelet endothelial cell adhesion molecule, PECAM-1 (CD31) is a 130-kDa glycoprotein, member of the immunoglobulin superfamily, which is involved in transendothelial migration of leukocytes. It is expressed on endothelial cells, lymphocytes, monocytes, neutrophils, basophils and platelets. We present data showing that soluble PECAM-1 is significantly increased in sera of multiple sclerosis patients with active, gadolinium enhancing lesions. Since we have found increased levels of sPECAM-1 in sera of patients with active MRI lesions, but not in those of patients without enhancing lesions, the molecule may be regarded as marker of MS activity. Soluble PECAM-1 may be involved in immunomodulatory mechanism leading to inhibition of migration of leukocytes in MS.

sPECAM‐1 in serum and CSF of acute ischaemic stroke patients

Objectives– As platelet endothelial cell adhesion molecule‐1 (PECAM‐1) is one of key mediators of transendothelial migration of leucocytes during inflammation, and inflammatory reaction is observed in cerebral ischaemia, we decided to determine the levels of soluble PECAM‐1 (sPECAM‐1) in serum and cerebrospinal fluid (CSF) of patients with acute stroke. Material and methods– Twenty‐three patients with first‐ever in a lifetime completed ischaemic stroke have been studied. CSF and blood samples were obtained within 24 h of the onset of stroke and the levels of sPECAM‐1 in serum and CSF were quantified by ELISA. Results– Stroke patients displayed statistically significant higher levels of sPECAM‐1 in sera and CSF in comparison with control group. The levels were significantly higher in serum than in CSF, correlated between each other, and CSF sPECAM‐1 fraction was blood‐derived. Conclusion – Our results indirectly suggest that PECAM‐1 may play a role in the pathophysiological events during early phase of ischaemic stroke.

CCL5, CXCL10 and CXCL11 Chemokines in Patients with Active and Stable Relapsing-Remitting Multiple Sclerosis

Objective: Chemokines are involved in the migration of inflammatory cells to the central nervous system in multiple sclerosis (MS). The aim of our study was to estimate the concentrations of CCL5, CXCL10 and CXCL11 in serum and cerebrospinal fluid (CSF) samples of relapsing-remitting MS (RRMS) patients during both relapse and stable disease, and to compare the results with those of controls. We also decided to evaluate the effect of methylprednisolone (MP) therapy on CCL5, CXCL10 and CXCL11 serum concentrations in MS patients with relapse. Methods: The study groups consisted of 17 RRMS patients during relapse, 30 RRMS patients in remission and 25 patients with tension headache with no symptoms of inflammatory disease as controls. In the group of relapsing MS patients, blood samples were obtained before steroid therapy and after a 5-day treatment with MP at a dose of 1 g i.v. once daily. Chemokine levels were measured by ELISA. Results: CXCL10 levels were significantly higher in the CSF of MS patients both during relapse (mean ± SD, 298.2 ± 143.8 pg/ml) and stable disease (323.7 ± 183 pg/ml) in comparison with the control group (152.4 ± 97.7 pg/ml; p < 0.001). CSF levels of CCL5 were significantly higher in relapsing MS patients (8.74 ± 6.18 pg/ml) in comparison with stable MS patients (4.4 ± 3.9 pg/ml, p = 0.005). CXCL11 levels of MS patients did not significantly differ from control values. There was no effect of MP therapy on serum levels of CCL5, CXCL10 and CXCL11. Conclusions: These observations suggest involvement of CXCL10 and CCL5 but not CXCL11 in the pathogenesis of MS. CCL5 may induce the recruitment of inflammatory cells in acute-stage MS.

Investigational C-C chemokine receptor 2 antagonists for the treatment of autoimmune diseases

Background: C-C chemokine receptor 2 (CCR2) antagonists belong to a group of chemokine blockers, which represent a new strategy for inflammatory diseases treatment by interfering with the complex system of chemokines and their receptors. A number of CCR2 antagonists are being developed for treatment of autoimmune diseases by different pharmaceutical and biotechnological companies. Objective: In this article the dark and the bright side of therapeutic CCR2 antagonism is discussed, with a view to its potential efficacy in various autoimmune diseases, in which clinical trials are already in progress, such as multiple sclerosis and rheumatoid arthritis. We describe different modes of possible interactions with CCR2–chemokine CC motif ligand 2 (CCL2) axis, usefulness of experimental animal models, continuing clinical trials and future perspectives of CCR2 antagonists. Methods: Until now only a few peer-reviewed articles providing data on the progress of preclinical and clinical trials with CCR2 antagonists have been published; therefore, we also present data based on preliminary reports, obtained from a number of press releases, conference communications and from the PharmaProjects database. Results/Conclusion: Although there is growing evidence for a great therapeutic potential of CCR2 blockade in autoimmune diseases, especially well documented in experimental animal models, so far clinical trials with CCR2 antagonists in humans have been moderately encouraging or even disappointing, indicating a need to further elucidate the complex system of chemokine interactions.

In vivo effect of interferon-β 1a on interleukin-12 and TGF-β1 cytokines in patients with relapsing–remitting multiple sclerosis

We have studied in vivo effect of interferon‐β 1a (IFN‐β 1a) (6 MIU once weekly i.m.) on interleukin‐12 (IL‐12) and transforming growth factor‐β1 (TGF‐β1) serum levels during 6 months of therapy in group of 20 patients with relapsing–remitting multiple sclerosis (MS). IL‐12 and TGF‐β1 concentrations were measured by enzyme linked immunoabsorbent assay (ELISA). There was a significant increase of IL‐12 levels in MS patients in comparison with control group, suggesting a role of this cytokine in immunity of MS. We have also found a significant increase of TGF‐β1 levels after 6 months of therapy with IFN‐β 1a, however, there was no in vivo effect of the therapy on IL‐12 levels. The results suggest that IFN‐β 1a may exert its action through up‐ regulation and increase secretion of TGF‐β1.

Is MS an inflammatory or primary degenerative disease

Multiple sclerosis (MS) is characterized by multiple areas of inflammation, demyelination and neurodegeneration. Multiple molecular and cellular components mediate neuroinflammation in MS. They involve: adhesion molecules, chemokines, cytokines, matalloproteases and the following cells: CD4+ T cells, CD8+ T cells, B cells, microglia and macrophages. Infiltrating Th1 CD4+ T cells secrete proinflammatory cytokines. They stimulate the release of chemokines, expression of adhesion molecules and can be factors that cause damage to the myelin sheath and axons. Chemokines stimulate integrin activation, mediate leukocyte locomotion on endothelial cells and participate in transendothelial migration. CD8+ cells can directly damage axons. B cells are involved in the production of antibodies which can participate in demyelination. B cells can also function as antigen presenting cells and contribute to T cell activation. Neuroinflammation is not only present in relapsing–remitting MS, but also in the secondary and primary progressive forms of the disease. The association between inflammation consisting of T cells, B cells, plasma cells and macrophages and axonal injury exists in MS patients including the progressive forms of the disease. The above association does not exclude the possibility that neurodegeneration can exist independently from inflammation. Very little inflammation is seen in cortical MS plaques. Anti-inflammatory therapies with different mode of action change the course of MS. Anti-inflammatory and immunomodulatory treatments are beneficial in the early relapsing stage of MS, but these treatments are ineffective in secondary progressive and primary progressive MS. In the stage of progressive MS, inflammation becomes trapped behind a closed or repaired blood–brain barrier. In such a situation current immunomodulatory, immunosuppressive or anti-inflammatory treatments might not reach this inflammatory process to exert a beneficial effect.