Pharmacogenomics of multiple sclerosis: in search for a personalized therapy

Extracellular Vesicles as Pro- and Anti-inflammatory Mediators, Biomarkers and Potential Therapeutic Agents in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease of the central nervous system (CNS) characterized by multiple demyelinating lesions in the spinal cord and brain. Neuronal disruption caused by myelin loss or demyelination, which may accompany axonal changes, leads to multiple neurological symptoms. They may transiently appear for weeks during periods of disease worsening (relapse) in relapsing-remitting form of MS (RRMS). Although a number of genetic, metabolic and environmental factors influencing the development of MS have been identified, the precise mechanisms involved in the CNS tissue damage in MS are still poorly understood. Recent studies have revealed a significant role of circulating extracellular vesicles (EVs) in many diseases. EVs are known to serve as a cellular communication tool between two cell types either in close proximity or in different parts of the body. During the recent development in understanding of the pathogenesis of MS, studies have revealed the possible role of EVs in MS. Furthermore, circulating EVs can be used as a biomarker for monitoring disease progression and activity of MS, and they can also be therapeutic reagents or targets of therapy. In this review we overview and discuss in detail about generation of EVs and their diversified roles in MS.

Therapeutic Value of Single Nucleotide Polymorphisms on the Efficacy of New Therapies in Patients with Multiple Sclerosis

The introduction of new therapies for the treatment of multiple sclerosis (MS) is a very recent phenomenon and little is known of their mechanism of action. Moreover, the response is subject to interindividual variability and may be affected by genetic factors, such as polymorphisms in the genes implicated in the pathologic environment, pharmacodynamics, and metabolism of the disease or in the mechanism of action of the medications, influencing the effectiveness of these therapies. This review evaluates the impact of pharmacogenetics on the response to treatment with new therapies in patients diagnosed with MS. The results suggest that polymorphisms detected in the GSTP1, ITGA4, NQO1, AKT1, and GP6 genes, for treatment with natalizumab, ZMIZ1, for fingolimod and dimethyl fumarate, ADA, for cladribine, and NOX3, for dimethyl fumarate, may be used in the future as predictive markers of treatment response to new therapies in MS patients. However, there are few existing studies and their samples are small, making it difficult to generalize the role of these genes in treatment with new therapies. Studies with larger sample sizes and longer follow-up are therefore needed to confirm the results of these studies.

Biomarkers of treatment response in multiple sclerosis

Multiple sclerosis (MS) is considered a heterogeneous disease with respect to disease progression and treatment response, which have both remained highly unpredictable. With an increasing number of available disease modifying therapies, strategies for treatment allocation in the individual patient or subgroup of patients has become more important. Therefore biomarkers, which will identify subgroups of MS patients and predict treatment response early in the course of the disease, are urgently needed. Here we review current and emerging biomarkers, as well as study concepts for identification of new biomarkers in MS.

Inhibition of endogenous phosphodiesterase 7 promotes oligodendrocyte precursor differentiation and survival

During the development of the central nervous system (CNS), oligodendrocyte precursors (OPCs) are generated in specific sites within the neural tube and then migrate to colonize the entire CNS, where they differentiate into myelin-forming oligodendrocytes. Demyelinating diseases such as multiple sclerosis (MS) are characterized by the death of these cells. The CNS reacts to demyelination and by promoting spontaneous remyelination, an effect mediated by endogenous OPCs, cells that represent approximately 5-7 % of the cells in the adult brain. Numerous factors influence oligodendrogliogenesis and oligodendrocyte differentiation, including morphogens, growth factors, chemotropic molecules, extracellular matrix proteins, and intracellular cAMP levels. Here, we show that during development and in early adulthood, OPCs in the murine cerebral cortex contain phosphodiesterase-7 (PDE7) that metabolizes cAMP. We investigated the effects of different PDE7 inhibitors (the well-known BRL-50481 and two new ones, TC3.6 and VP1.15) on OPC proliferation, survival, and differentiation. While none of the PDE7 inhibitors analyzed altered OPC proliferation, TC3.6 and VP1.15 enhanced OPC survival and differentiation, processes in which ERK intracellular signaling played a key role. PDE7 expression was also observed in OPCs isolated from adult human brains and the differentiation of these OPCs into more mature oligodendroglial phenotypes was accelerated by treatment with both new PDE7 inhibitors. These findings reveal new roles for PDE7 in regulating OPC survival and differentiation during brain development and in adulthood, and they may further our understanding of myelination and facilitate the development of therapeutic remyelination strategies for the treatment of MS.

Natalizumab inhibits the expression of human endogenous retroviruses of the W family in multiple sclerosis patients: a longitudinal cohort study

Background:

Several viruses were reported as co-factors triggering the pathogenesis of multiple sclerosis (MS), including the endogenous retroviruses of the HERV-W family, that were also proposed as biomarkers of disease progression and therapy outcome.

Objective:

The objective of this article is to clarify whether in MS patients treatment with natalizumab has effects on MSRV/syncytin-1/HERV-W expression and the possible relationship with disease outcome.

Methods:

Peripheral blood mononuclear cells were collected from 22 patients with relapsing–remitting disease, at entry and after three, six and 12 months of treatment with natalizumab. The cell subpopulations and the expression of MSRV env/syncytin-1/HERV-W env were analyzed by flow cytometry and by discriminatory env-specific RT-PCR assays.

Results:

By flow cytometry the relative amounts of T, NK and monocyte subpopulations were shown to remain fairly constant. A relative increase of B lymphocytes was observed at three to six months ( p = 0.033). The MSRV env and syncitin-1 transcripts were reduced at six to 12 months of therapy ( p = 0.0001). Accordingly, at month 12, the plasma-membrane levels of the HERV-W env protein were reduced ( p = 0.0001). B cells, NK and monocytes but not T cells expressed the HERV-W env protein. None of the patients relapsed during therapy.

Conclusion:

Effective therapy with natalizumab downregulates MSRV/syncytin-1/HERV-W expression.

Pharmacogenomics and multiple sclerosis: moving toward individualized medicine

Notwithstanding the availability of disease-modifying treatments including interferon-β, glatiramer acetate, and natalizumab, a considerable proportion of multiple sclerosis (MS) patients experience continued progression of disease, clinical relapses, disease activity on MRI, and adverse effects. Application of gene expression, proteomic or genomic approaches is universally accepted as a suitable strategy toward the identification of biomarkers with predictive value for beneficial/poor clinical response to therapy and treatment risks. This review focuses on recent progress in research on the pharmacogenomics of disease-modifying therapies for MS. Although MS drug response biomarkers are not yet routinely implemented in the clinic, the diversity of reported, promising molecular markers is rapidly increasing. Even though most of these markers await further validation, given time, this research is likely to empower neurologists with an enhanced armamentarium to facilitate rational decisions on therapy and patient management.

Clinical predictors of response to immunomodulators for multiple sclerosis

OBJECTIVES: To determine, based on clinical criteria, the proportion of multiple sclerosis (MS) patients responsive to immunomodulators (RI) and nonresponsive to immunomodulators (NRI), and to ascertain whether clinical and epidemiological data differs between RI and NRI patient groups. METHODS: Patients were assessed on rate of exarcerbations per year, for the period before and after commencement of treatment. The RI and NRI groups were compared for several clinical and epidemiological characteristics. DISCUSSION AND CONCLUSION: A total of 31.4% of the patients were nonresponders to the immunomodulatory treatment. The main predictors of immunomodulatory response were early diagnostic and commencement of therapy and high rate of annual exacerbations prior to treatment. Given the arsenal of medication options available for MS management, screening potential candidates for different therapeutic approaches are critical to optimize evolution of patients with the disease.

FGF-2 and Anosmin-1 are selectively expressed in different types of multiple sclerosis lesions

Multiple sclerosis is a demyelinating disease that affects ≈ 2,000,000 people worldwide. In the advanced stages of the disease, endogenous oligodendrocyte precursors cannot colonize the lesions or differentiate into myelinating oligodendrocytes. During development, both FGF-2 and Anosmin-1 participate in oligodendrocyte precursor cell migration, acting via the FGF receptor 1 (FGFR1). Hence, we performed a histopathological and molecular analysis of these developmental modulators in postmortem tissue blocks from multiple sclerosis patients. Accordingly, we demonstrate that the distribution of FGF-2 and Anosmin-1 varies between the different types of multiple sclerosis lesions: FGF-2 is expressed only within active lesions and in the periplaque of chronic lesions, whereas Anosmin-1 is upregulated within chronic lesions and is totally absent in active lesions. We show that the endogenous oligodendrocyte precursor cells recruited toward chronic-active lesions express FGFR1, possibly in response to the FGF-2 produced by microglial cells in the periplaque. Also in human tissue, FGF-2 is upregulated in perivascular astrocytes in regions of the normal-appearing gray matter, where the integrity of the blood-brain barrier is compromised. In culture, FGF-2 and Anosmin-1 influence adult mouse oligodendrocyte precursor cell migration in the same manner as at embryonic stages, providing an explanation for the histopathological observations: FGF-2 attracts/enhances its migration, which is hindered by Anosmin-1. We propose that FGF-2 and Anosmin-1 are markers for the histopathological type and the level of inflammation of multiple sclerosis lesions, and that they may serve as novel pharmacogenetic targets to design future therapies that favor effective remyelination and protect the blood-brain barrier.

Overview of computational methods employed in early-stage drug discovery

BACKGROUND

The understanding of biomolecular interactions ultimately depends on knowledge about the structural and dynamic details of the interacting system. Rational structure-based drug design implements computational methodology in this rationale.

DISCUSSION

Together with increasing throughput of structural biology, molecular modeling has progressively contributed to rational drug design and elucidation of nontoxic and patient-tailored interventions, helping to make drug development more cost-efficient. But in this challenging time for the pharmaceutical industry, the successful discovery of novel therapeutics should rely on integration of computational modeling with experimentation when it comes to ligand-binding energetics, system flexibility and genetic diversity/heterogeneity of the target. Moreover, it appears that many drugs--even those for which specific receptors have been identified--intercalate in biological membranes, which could also become the actual target.

CONCLUSIONS

Understanding the drug-target and drug-unwanted-target interactions at the atomic level is fundamental in the initial phases of the drug development process. Molecular dynamics simulations and complementary computational methods are already contributing in this endeavor for the soluble pharmacological targets and show an increasing importance in the understanding of membrane-ligand interactions.

Metabonomic studies of schizophrenia and psychotropic medications: focus on alterations in CNS energy homeostasis

Schizophrenia is a severe neuropsychiatric disorder with a poorly understood etiology and progression. We and other research groups have found that energy metabolic pathways in the CNS are perturbed in many subjects with this disorder. Antipsychotic drugs that generally target neurotransmission are currently used for clinical management of the disorder, although these can also have marked effects on energy metabolism in the CNS and periphery. Recent proteomic and metabonomic studies have shown that molecular pathways associated with brain energy metabolism are altered in both the disorder and by antipsychotic treatments. This review focuses on discussion of these molecular alterations. Increased knowledge in this area could facilitate biomarker identification and drug discovery based on improving brain energy metabolism in this debilitating disorder.

Genetic polymorphisms, their allele combinations and IFN-beta treatment response in Irish multiple sclerosis patients

INTRODUCTION

IFN-beta is widely used as first-line immunomodulatory treatment for multiple sclerosis. Response to treatment is variable (30-50% of patients are nonresponders) and requires a long treatment duration for accurate assessment to be possible. Information about genetic variations that predict responsiveness would allow appropriate treatment selection early after diagnosis, improve patient care, with time saving consequences and more efficient use of resources.

MATERIALS & METHODS

We analyzed 61 SNPs in 34 candidate genes as possible determinants of IFN-beta response in Irish multiple sclerosis patients. Particular emphasis was placed on the exploration of combinations of allelic variants associated with response to therapy by means of a Markov chain Monte Carlo-based approach (APSampler).

RESULTS

The most significant allelic combinations, which differed in frequency between responders and nonresponders, included JAK2-IL10RB-GBP1-PIAS1 (permutation p-value was p(perm) = 0.0008), followed by JAK2-IL10-CASP3 (p(perm) = 0.001).

DISCUSSION

The genetic mechanism of response to IFN-beta is complex and as yet poorly understood. Data mining algorithms may help in uncovering hidden allele combinations involved in drug response versus nonresponse.

Biologic therapy for rheumatoid arthritis: clinical efficacy and predictors of response

We present evidence of a link between interferonβ-1b (IFN-β) and G-protein signaling by demonstrating that IFN-β can induce the expression of the negative regulator of G-protein signaling 1 (RGS1). RGS1 reduces G-protein activation and immune cell migration by interacting with heterotrimeric G-proteins and enhancing their intrinsic GTPase activity. In this study, IFN-β treatment resulted in the induction of RGS1 in peripheral blood mononuclear cells (PBMCs), monocytes, T cells, and B cells. Induction of RGS1 by IFN-β was concentration dependent and observed at both the RNA and protein level. Other members of the RGS family were not induced by IFN-β, and induction of RGS1 required the activation of the IFN receptor. In addition, RGS1 induction was observed in PBMCs obtained from IFN-β-treated multiple sclerosis patients suggesting a possible, as yet unexplored, involvement of G-protein regulation in disease treatment. The upregulation of RGS1 by IFN-β has not been previously reported.

United Europeans for development of pharmacogenomics in multiple sclerosis network

Multiple sclerosis (MS) is a chronic inflammatory, disabling disease of the CNS. A recent study has estimated the annual cost of MS in Europe at €12.5 billion. There is no definitive cure for the disease. Immunomodulatory therapies, such as IFN-β and glatiramer acetate, are only partially effective. Various new therapies in the final stages of clinical trials are being developed in the absence of efficacy biomarkers. Hence, there is a pressing need for identification of MS treatment response biomarkers. The focus of the multicenter research initiative United Europeans for the development of pharmacogenomics in MS (UEPHA*MS) is to promote and improve training opportunities in the novel supradisciplinary area of pharmacogenomics, biomarker research and systems biology applied to MS. UEPHA*MS is a Marie Curie Initial Training network funded by the 7th Framework Programme of the European Commission. The main scientific goals of this network are both to enhance our knowledge of the mechanisms determining response outcomes of existing immunomodulatory therapies and to identify novel therapeutic opportunities. UEPHA*MS is composed of 11 internationally recognized research teams from five countries with an assortment of expertise in complementary disciplines. The UEPHA*MS network will provide a coherent and internationally competitive platform for the training of young scientists based on multidisciplinary state-of-the-art laboratory-based and network-wide activities. This network will be instrumental in priming young scientists for Europe’s collective effort toward improved provision of healthcare based on personalized medicine.

The genetics of acute lung injury: looking back and pointing the way forward

Individual genetic factors have long been suspected of playing a major role in susceptibility to acute lung injury and acute respiratory distress syndrome. Flores and colleagues evaluate the quality of published studies testing the relationships between variation in candidate genes and susceptibility to lung injury syndromes or worsened outcome in patients with these conditions. Their results demonstrate that while important advances have been made in this area, attention should be paid to improving the methodology of future studies in order to minimize the chances of publishing false-positive results.