Intravenous immunoglobulin in MS: Promise or failure?

Wnt signaling in remyelination in multiple sclerosis: friend or foe?

Myelination is critical to normal functioning of the vertebrate nervous system. In demyelinating diseases such as multiple sclerosis, oligodendrocytes, the myelinating cells in the central nervous system, are targeted, resulting in myelin loss, axonal damage, and severe functional impairment. While spontaneous remyelination has been proven a failure in multiple sclerosis, understanding the molecular mechanism underlying oligodendrocyte biology, myelination, and remyelination becomes crucial. To date, a series of signaling pathways in regulating oligodendrocyte development and remyelination have been suggested and, among them, the Wnt/β-catenin/Tcf pathway has been considered a negative factor in the myelinating process. However, this notion has been challenged by recent studies, which showed a pro-myelinating effect of this pathway. This review summarizes the current contradictory concepts concerning the role of the Wnt pathway in the oligodendrocyte development and remyelination process, attempts to address the potential mechanism underlying this controversy, and recommends caution in targeting the Wnt pathway as a potential demyelinating therapy.

Role of pathogens in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating autoimmune disease of the central nervous system (CNS). Although the etiology of MS is unknown, genetic and environmental factors play a role. Infectious pathogens are the likely environmental factors involved in the development of MS. Pathogens associated with the development or exacerbation of MS include bacteria, such as Mycoplasma pneumoniae and Chlamydia pneumoniae, the Staphylococcus aureus-produced enterotoxins that function as superantigens, viruses of the herpes virus (Epstein-Barr virus and human herpesvirus 6) and human endogenous retrovirus (HERV) families and the protozoa Acanthamoeba castellanii. Evidence, from studies with humans and animal models, supporting the association of these various pathogens with the development and/or exacerbation of MS will be discussed along with the potential mechanisms including molecular mimicry, epitope spreading and bystander activation. In contrast, infection with certain parasites such as helminthes (Schistosoma mansoni, Fasciola hepatica, Hymenolepis nana, Trichuris trichiura, Ascaris lumbricoides, Strongyloides stercolaris, Enterobius vermicularis) appears to protect against the development or exacerbation of MS. Evidence supporting the ability of parasitic infections to protect against disease will be discussed along with a brief summary of a recent Phase I clinical trial testing the ability of Trichuris suis ova treatment to improve the clinical course of MS. A complex interaction between the CNS (including the blood-brain barrier), multiple infections with various infectious agents (occurring in the periphery or within the CNS), and the immune response to those various infections may have to be deciphered before the etiology of MS can be fully understood.

Polyclonal immunoglobulin G for autoimmune demyelinating nervous system disorders

Demyelinating diseases with presumed autoimmune pathogenesis are characterised by direct or indirect immune-mediated damage to myelin sheaths, which normally surround nerve fibres to ensure proper electrical nerve conduction. Parenteral administration of polyclonal IgG purified from multi-donor human plasma pools may beneficially modulate these misguided immune reactions via several mechanisms that are outlined in this review. Convincing therapeutic evidence from controlled trials now exists for certain disorders of the peripheral nervous system, including Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy, and multifocal motor neuropathy. In addition, there is evidence for potential therapeutic benefits of IgG in patients with chronic inflammatory demyelinating diseases of the central nervous system, including multiple sclerosis and neuromyelitis optica. This review introduces these disorders, briefly summarises the established treatment options, and discusses therapeutic evidence for the use of polyclonal immunoglobulins with a particular emphasis on recent clinical trials and meta-analyses.

Long-term use of glatiramer acetate by 11 pregnant women with multiple sclerosis: a retrospective, multicentre case series

BACKGROUND

Glatiramer acetate is a US FDA category B drug with regard to use by pregnant women with multiple sclerosis (MS). There are no data currently available for the continuous use of glatiramer acetate during pregnancy.

OBJECTIVE

To assess the risks and benefits of glatiramer acetate used throughout pregnancy among women with active MS.

DESIGN

Retrospective and multicentre case series.

SETTINGS

Outpatient services of academic and private institutions caring for patients with MS in Brazil.

PATIENTS

Eleven women with MS and their children were assessed.

INTERVENTION

Retrospective evaluation of women with MS who received glatiramer acetate continuously for at least 7 months during pregnancy. This evaluation was performed by the neurologist responsible for the patient. Children aged 1 year and over, born to mothers who received glatiramer acetate during pregnancy, were assessed using the Denver II developmental screening test.

MAIN OUTCOME MEASUREMENTS

Obstetric, neonatal and developmental outcomes.

RESULTS

No drug-related obstetric complications were observed. No specific drug-related malformations, neonatal complications or developmental abnormalities were observed in the children. Postnatal MS relapse rates remained significantly lower than antenatal rates in these patients.

CONCLUSIONS

No deleterious effects from glatiramer acetate were observed in these pregnant women with MS or in their offspring. No increment in postnatal relapse rate was observed. However, the use of glatiramer acetate during pregnancy should be restricted to the most difficult cases, in which the benefits clearly outweigh the risks.

Expanding Tregs with IVIg

In this issue of Blood, Ephrem et al demonstrate that IVIg expands CD4+CD25+FoxP3+ T regulatory cells (Tregs) and enhances their function in vivo and in vitro. Their findings shed new light on the elusive mechanism of action of IVIg in ameliorating autoimmune diseases.