Chemokine network in multiple sclerosis: role in pathogenesis and targeting for future treatments

Interferon-β1bin multiple sclerosis

In 1993, interferon (IFN)-beta(1b) for subcutaneous injection became the first US FDA-approved immunomodulatory treatment for multiple sclerosis, a chronic inflammatory disease of the CNS. In this review of IFN-beta(1b), we first present a short introduction to multiple sclerosis and currently available therapeutics. We then summarize current knowledge about the biochemical structure of IFN-beta(1b), as well as pharmacokinetics and pharmacodynamics, including data on putative mechanisms underlying therapeutic as well as adverse effects. Furthermore, a critical review of ongoing and recently published clinical trials investigating IFN-beta(1b) in multiple sclerosis will be provided. Main topics are: trials investigating IFN-beta(1b) after a first clinical event, at higher dosages or in comparison to once-weekly subcutaneous IFN-beta(1a) injections, 16 years of long-term follow-up, IFN-beta(1b) in Japanese patients, the role of neutralizing antibodies, biomarkers for the prediction of therapy response, IFN-beta(1b) and pregnancy, and IFN-beta(1b) treatment of children with multiple sclerosis. Finally, we discuss how novel drugs, especially monoclonal antibodies and orally administered immunosuppressants, might soon challenge the position of this well-established agent on the multiple sclerosis therapeutics market.

Progranulin gene variability increases the risk for primary progressive multiple sclerosis in males

Progranulin (GRN) gene variability has been analyzed in a sample of 354 patients with multiple sclerosis (MS) compared with 343 controls. No significant differences were observed, but by stratifying according to MS subtypes, a significant increased frequency of the rs2879096 TT genotype was found in primary progressive MS (PPMS) patients versus controls (16.0 vs 3.5%, P=0.023, odds ratio (OR) 5.2, 95% confidence interval (CI) 1.2-21.4). In addition, in PPMS, an association with the C allele of rs4792938 was observed (55.3 vs 33.5%, P=0.011, OR 2.4, 95% CI 1.2-4.7). An independent population was studied as replication, failing to confirm results previously obtained. Stratifying according to gender, an association with rs4792938 C allele was found in male PPMS patients compared with controls (40.7 vs 26.9%, P=0.002, OR 1.87, 95% CI 1.2-2.8). An association with the rs2879096T allele was observed (29.2 in patients compared with 18.9% in controls, P=0.012, OR 1.77, 95% CI 1.1-2.8). Haplotype analysis showed that TC haplotype frequency is increased in PPMS male patients compared with male controls (25.7 vs 16.6%; P=0.02, OR 1.69, 95% CI 1.1-2.7), whereas the respective GC haplotype seems to exert a protective effect, as its frequency is decreased in patients compared with controls (55.8% vs 70.9%; P=0.001, OR 0.52, 95% CI 0.4-0.8). Therefore, GRN haplotypes likely influence the risk of developing PPMS in males.

Cerebrospinal fluid progranulin levels in patients with different multiple sclerosis subtypes

Progranulin has recently attracted attention due to the discovery of mutations in its encoding gene (GRN) in several cases of frontotemporal lobar degeneration, but also for a possible role in inflammatory processes. In adult central nervous system, GRN mRNA is expressed in forebrain, olfactory bulbs and spinal cord. Progranulin cerebrospinal fluid (CSF) levels were evaluated in 55 patients with multiple sclerosis (MS) as well as in 35 subjects with non-inflammatory neurological diseases (NIND), 7 individuals with other inflammatory neurological disease (OIND) and 8 controls (CON), matched for ethnic background, gender and age. No statistically significant differences were found in patients compared with either NIND, OIND or CON (P>0.05), even stratifying according to disease subtype or gender. A positive correlation between progranulin CSF levels and age was observed in patients (rho=0.29, P=0.03). According to these data, progranulin does not likely play a major role in the pathogenesis of MS.

MDC/CCL22 intrathecal levels in patients with multiple sclerosis

MDC/CCL22 has been detected in the brain of mice with experimental autoimmune encephalomyelitis. MDC/CCL22 cerebrospinal fluid levels were evaluated in 56 patients with multiple sclerosis (MS) and in 17 controls. No significant differences were found, even when stratifying patients according to the disease subtype. Stratifying by gender, significantly increased MDC/CCL22 levels were observed in female patients when compared with female controls and male patients (109.03 versus 98.54 and 99.37 pg/mL, P = 0.034 and 0.018, respectively). Therefore, MDC/CCL22 is likely to play a role in the development of MS in females only, possibly influencing the intracerebral recruitment of Th2 cells, which produce anti-inflammatory cytokines. Multiple Sclerosis 2008; 14: 547—549. http://msj.sagepub.com

A network analysis of the human T-cell activation gene network identifies JAGGED1 as a therapeutic target for autoimmune diseases

Understanding complex diseases will benefit the recognition of the properties of the gene networks that control biological functions. Here, we set out to model the gene network that controls T-cell activation in humans, which is critical for the development of autoimmune diseases such as Multiple Sclerosis (MS). The network was established on the basis of the quantitative expression from 104 individuals of 20 genes of the immune system, as well as on biological information from the Ingenuity database and Bayesian inference. Of the 31 links (gene interactions) identified in the network, 18 were identified in the Ingenuity database and 13 were new and we validated 7 of 8 interactions experimentally. In the MS patients network, we found an increase in the weight of gene interactions related to Th1 function and a decrease in those related to Treg and Th2 function. Indeed, we found that IFN-ß therapy induces changes in gene interactions related to T cell proliferation and adhesion, although these gene interactions were not restored to levels similar to controls. Finally, we identify JAG1 as a new therapeutic target whose differential behaviour in the MS network was not modified by immunomodulatory therapy. In vitro treatment with a Jagged1 agonist peptide modulated the T-cell activation network in PBMCs from patients with MS. Moreover, treatment of mice with experimental autoimmune encephalomyelitis with the Jagged1 agonist ameliorated the disease course, and modulated Th2, Th1 and Treg function. This study illustrates how network analysis can predict therapeutic targets for immune intervention and identified the immunomodulatory properties of Jagged1 making it a new therapeutic target for MS and other autoimmune diseases.

Therapeutic neutralization of CXCL10 decreases secondary degeneration and functional deficit after spinal cord injury in mice

Inflammation plays a critical role in the secondary degenerative response to spinal cord injury (SCI). The influx of inflammatory cells following SCI is preceded by the expression of specific chemoattractants, including chemokines. The chemokine CXCL10 is a potent T lymphocyte recruiter and has been strongly implicated in the pathology of many CNS disorders. We have previously demonstrated that CXCL10 exacerbates secondary degeneration by blocking the function of CXCL10 prior to SCI. Here we administered neutralizing antibodies against CXCL10 1 h after SCI in order to investigate the efficacy of this therapeutic intervention in abating histologic and functional deficit following acute SCI and further assess the functional role of CXCL10 in secondary degeneration. Neutralization of CXCL10 significantly reduced inflammation, apoptosis, neuronal loss and whole tissue loss. Notably, this therapeutic treatment also promoted revascularization of the injured spinal cord and functional recovery. These data suggest that anti-CXCL10 antibody treatment is a viable therapeutic strategy for acute SCI.

TRAIL, CXCL10 and CCL2 plasma levels during long-term Interferon-β treatment of patients with multiple sclerosis correlate with flu-like adverse effects but do not predict therapeutic response

High serum levels of soluble TRAIL (sTRAIL) before or during the first year of Interferon-beta (IFN-beta) therapy were shown to predict an individual therapeutic response of patients with relapsing-remitting multiple sclerosis (RRMS). Here, we investigated whether sTRAIL plasma levels during long-term IFN-beta treatment correlate with future therapeutic response or adverse effects of treatment. Postinjection short-time bursts of sTRAIL were associated with flu-like symptoms and IP-10/CXCL10 as well as MCP-1/CCL2 induction, and were detected after up to 6 years of continuous IFN-beta therapy. However, neither sTRAIL nor chemokine levels allowed prediction of one- and two-year clinical treatment response in 30 RRMS patients, prospectively followed by blinded investigators.

Candidate gene analysis of SPARCL1 gene in patients with multiple sclerosis

Recently, proteomic analysis in cerebrospinal fluid (CSF) from patients with MS identified four proteins which are present in MS but not in normal human CSF, including SPARCL1, an extracellular matrix-associated protein member of the SPARC family. One hundred eighty-six patients with MS and 185 age-matched controls were genotyped for A/G single nucleotide polymorphism (SNP) in exon 1 (rs1049539), C/G SNP in exon 4 (rs1049544), resulting in a substitution of an aspartate with an histidine, and A/G substitution in the exon 5 (rs1130643), leading to the substitution of alanine with threonine. No significant differences in either allelic or genotypic frequency of the three SNPs were found (P>0.05), even in stratifying MS patients according to the course of the disease. Stratifying according to gender, a trend towards a decreased frequency of the C/C genotype of the rs1049544 was observed in male patients as compared with male controls (30.2% versus 44.0%; P=0.217). Despite proteomic studies in CSF from MS patients suggested an important role for SPARCL1 in the development of the disease, SPARCL1 gene does not appear to act as susceptibility factor for MS in the population investigated here. However, the frequency of the C/C genotype of rs1049544 was decreased in male patients, possibly conferring a lower risk of developing MS in male population. Further studies are needed to clarify this issue.

CXCL10 haplotypes and multiple sclerosis: association and correlation with clinical course

CXCL10 (interferon-gamma-inducible protein-10) levels are increased in cerebrospinal fluid of multiple sclerosis (MS) patients with symptomatic attacks of inflammatory demyelination, supporting a role for this molecule in MS pathogenesis. Two hundred and twenty-six patients with MS and 235 controls were genotyped for G --> C and T --> C single nucleotide polymorphisms (SNPs) in exon 4 of CXCL10 gene. Haplotypes were tested for association and correlated with clinical variables. The two SNPs studied were in complete linkage disequilibrium. None of the determined haplotypes was associated with MS. However, carriers of the GGTT haplotype (defined as wild type, according to the sequence in National Centre for Biotechnology Information (NCBI) database) had a significantly lower progression index than non-carriers (P = 0.016). Furthermore, amongst patients who had an initial relapsing remitting (RR) course of the disease, the time between onset and second episode was significantly longer in GGTT carriers (P = 0.021). Considering secondary progressive (SP)-MS patients, the time between the initial RR form and the subsequent worsening to SP was longer in this group (P = 0.08). Therefore, the GGTT haplotype of the CXCL10 gene is not a susceptibility factor for the development of MS, but is probably to influence the course of MS, possibly contributing to slow down the progression of the disease.

Functional diversity of chemokines and chemokine receptors in response to viral infection of the central nervous system

Encounters with neurotropic viruses result in varied outcomes ranging from encephalitis, paralytic poliomyelitis or other serious consequences to relatively benign infection. One of the principal factors that control the outcome of infection is the localized tissue response and subsequent immune response directed against the invading toxic agent. It is the role of the immune system to contain and control the spread of virus infection in the central nervous system (CNS), and paradoxically, this response may also be pathologic. Chemokines are potent proinflammatory molecules whose expression within virally infected tissues is often associated with protection and/or pathology which correlates with migration and accumulation of immune cells. Indeed, studies with a neurotropic murine coronavirus, mouse hepatitis virus (MHV), have provided important insight into the functional roles of chemokines and chemokine receptors in participating in various aspects of host defense as well as disease development within the CNS. This chapter will highlight recent discoveries that have provided insight into the diverse biologic roles of chemokines and their receptors in coordinating immune responses following viral infection of the CNS.

P-selectin glycoprotein ligand-1 variable number of tandem repeats (VNTR) polymorphism in patients with multiple sclerosis

P-selectin glycoprotein ligand-1 (PSGL-1) is an important adhesion molecule involved in lymphocyte recruitment into the brain, which represents a crucial step in the pathogenesis of multiple sclerosis (MS). Three hundred twenty-one MS patients and 342 controls were genotyped for the presence of a polymorphism in the PSGL-1 gene, consisting of a variable number of tandem repeats (VNTR) originating three possible alleles: A, B and C, in order to test whether they influence the susceptibility and the course of the disease. No significant differences among allelic frequencies of A, B and C alleles in MS as compared with controls were observed. Stratifying patients according to the course of the disease, a significantly increased frequency of the shortest C allele in PP-MS was found (7.1%), either in comparison with controls (P=0.011) or with all other MS patients, who had acute inflammatory attacks at onset and an initial RR form (P=0.036). Besides, none of SP-MS patients was a carrier of the C allele and B carriers converted later from RR to SP course as compared with A/A subjects (after 15.8 rather than 8.8 years, P=0.01). In conclusion, the C allele of the VNTR polymorphism in PSGL-1 is likely to be associated with PP-MS. As this allele has been demonstrated to have a very low efficiency in mediating lymphocyte binding to brain endothelium during attacks, its high frequency in PP-MS could be related to the absence of exacerbations in such patients.

E-selectin A561C and G98T polymorphisms influence susceptibility and course of multiple sclerosis

Three hundred seven patients with MS and 300 controls were genotyped for G98T and A561C SNPs in the E-selectin gene, and genetic data were correlated with the course of the disease. The frequency of the T/T genotype of the G98T SNP was significantly increased in RR-MS patients compared with controls, while was absent in PP-MS. The frequency of the A561C SNP was significantly decreased in SP-MS compared with benign RR-MS. The T/T genotype of the G98T SNP is likely to confer an increased risk to develop MS. The A561C polymorphism seems to act as protective factor towards the progression to SP-MS.