Publications by authors named "Michael Carrithers"

Background: Major depressive disorder (MDD) is prevalent, yet sub-optimally treated among persons with multiple sclerosis (MS). We propose that exercise training may be a promising approach for treating depression in persons with MS who have MDD. Our primary hypothesis predicts a reduction in depression severity immediately after an exercise training intervention compared with minimal change in an attention control condition, and the reduction will be maintained during a follow-up period.

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The extraction of patient signs and symptoms recorded as free text in electronic health records is critical for precision medicine. Once extracted, signs and symptoms can be made computable by mapping to signs and symptoms in an ontology. Extracting signs and symptoms from free text is tedious and time-consuming.

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Disease phenotypes are characterized by signs (what a physician observes during the examination of a patient) and symptoms (the complaints of a patient to a physician). Large repositories of disease phenotypes are accessible through the Online Mendelian Inheritance of Man, Human Phenotype Ontology, and Orphadata initiatives. Many of the diseases in these datasets are neurologic.

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Article Synopsis
  • The study used network analysis to categorize subjects with relapsing-remitting multiple sclerosis based on their cumulative signs and symptoms from electronic medical records.
  • Different community structures were identified in bipartite and unipartite network graphs, highlighting five distinct communities in each that reflect varying symptom profiles.
  • While no pure subtypes of multiple sclerosis were identified, the research demonstrates that network analysis can effectively separate subjects into different subtype communities, suggesting the need for larger datasets to validate these findings.
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Black and Hispanic American patients frequently develop earlier onset of multiple sclerosis (MS) and a more severe disease course that can be resistant to disease modifying treatments. The objectives were to identify differential methylation of genomic DNA (gDNA) associated with disease susceptibility and treatment responses in a cohort of MS patients from underrepresented minority populations. Patients with MS and controls with non-inflammatory neurologic conditions were consented and enrolled under an IRB-approved protocol.

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Prior work demonstrated that epithelial V-like antigen (EVA), a cell surface adhesion molecule, is expressed in B lymphocytes and is necessary for the efficacy of anti-alpha integrin treatment of experimental autoimmune encephalomyelitis (EAE), the mouse model of human multiple sclerosis. EVA deficiency is associated with a severe clinical phenotype of EAE in the presence or absence of treatment. Histological analysis revealed enhanced B cell-mediated autoimmunity and deposition of antibody and complement within the brain and spinal cord.

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Prior work demonstrated that a splice variant of SCN5A, a voltage-gated sodium channel gene, acts as a cytoplasmic sensor for viral dsRNA in human macrophages. Expression of this channel also polarizes macrophages to an anti-inflammatory phenotype in vitro and in vivo. Here we utilized global expression analysis of splice variants to identify novel channel-dependent signaling mechanisms.

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Recent work demonstrated that a splice variant of a human macrophage voltage-gated sodium channel expressed on endosomes acts as an intracellular sensor for dsRNA, a viral-associated molecular pattern. Here our goal was to identify a candidate gene in a clinically relevant invertebrate model with related cellular and pattern recognition properties. The para gene in drosophila and other insects encodes voltage-gated sodium channels with similar electrophysiological properties to those found in vertebrate excitable membranes.

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Pattern recognition receptors contain a binding domain for pathogen-associated molecular patterns coupled to a signaling domain that regulates transcription of host immune response genes. Here, a novel mechanism that links pathogen recognition to channel activation and downstream signaling is proposed. We demonstrate that an intracellular sodium channel variant, human macrophage SCN5A, initiates signaling and transcription through a calcium-dependent isoform of adenylate cyclase, ADCY8, and the transcription factor, ATF2.

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Purpose: The purpose of this review is to discuss the selection and use of disease- modifying treatments for patients with relapsing forms of multiple sclerosis (MS).

Methods: PubMed was searched (1966-2014) using the terms multiple sclerosis, treatment, interferon, glatiramer acetate, dimethyl fumarate, fingolimod, teriflunomide, natalizumab, rituximab, and alemtuzumab.

Findings: MS is a chronic neurological disorder that can cause a substantial degree of disability.

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Article Synopsis
  • Mononuclear phagocytes play a critical role in the initial immune response to acute viral infections by recognizing viral components and injury signals.
  • Pattern recognition receptors (PRRs) like TLRs, RLRs, and NOD-like receptors are essential for triggering inflammatory responses and activating adaptive immunity.
  • Different neurotropic viruses, such as HSV, West Nile virus, and HIV, utilize unique strategies to manipulate and evade the innate immune system, influencing infection severity and the effectiveness of vaccines.
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Natalizumab inhibits the transmigration of activated T lymphocytes into the brain and is highly efficacious in multiple sclerosis (MS). However, from a pharmacogenomic perspective, its efficacy and safety in specific patients remain unclear. Here our goal was to analyze the effects of epithelial V-like antigen (EVA) on anti-alpha₄ integrin (VLA4) efficacy in a mouse model of MS, experimental autoimmune encephalomyelitis (EAE).

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Multiple sclerosis (MS) is the most common nontraumatic cause of neurologic disability in young adults. Despite treatment, progressive tissue injury leads to accumulation of disability in many patients. Here, our goal was to develop an immune-mediated strategy to promote tissue repair and clinical recovery in an MS animal model.

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Multiple sclerosis is the most common chronic inflammatory disease of the central nervous system and can cause severe neurological disability. Current immune therapy with beta-interferons, glatiramer acetate, immune suppressives, or selective adhesion molecule inhibitors can reduce the frequency and severity of acute attacks in a majority of patients but have little effect on the progressive phase of the disease. Patients who require aggressive immune therapy are also at risk for the development of potentially fatal opportunistic infections.

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Multiple sclerosis is the most common chronic inflammatory disease of the central nervous system and can cause severe neurological disability. Current immune therapy with beta-interferons, glatiramer acetate, immune suppressives, or selective adhesion molecule inhibitors can reduce the frequency and severity of acute attacks in a majority of patients but have little effect on the progressive phase of the disease. Patients who require aggressive immune therapy are also at risk for the development of potentially fatal opportunistic infections.

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Article Synopsis
  • Phagocytosis and intracellular processing of mycobacteria in macrophages involve precise coordination of various cellular activities, including uptake, signaling, and organelle movement.
  • Recent findings indicate that the voltage-gated sodium channel NaV1.5 enhances endosomal acidification and phagocytosis in human macrophages.
  • Knockdown of NaV1.5 impairs the uptake of mycobacteria and disrupts calcium signaling during phagosome maturation, highlighting the importance of this channel in regulating macrophage responses.
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Prior work demonstrated that immune surveillance of the brain occurs primarily through the blood-cerebrospinal (CSF) fluid barrier rather than the blood-brain barrier endothelium. Recently, we identified epithelial V-like antigen (EVA), an immunoglobulin-like adhesion molecule, as a regulator of blood-CSF barrier integrity in a mouse model. Here we characterized EVA expression and function in human choroid plexus epithelial cells and analyzed its role in CD4 T lymphocyte adhesion.

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Voltage-gated sodium channels initiate electrical signaling in excitable cells such as muscle and neurons. They also are expressed in non-excitable cells such as macrophages and neoplastic cells. Previously, in macrophages, we demonstrated expression of SCN8A, the gene that encodes the channel NaV1.

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Epithelial V-like antigen (EVA), a CD3-binding immunoglobulin-like protein, regulates embryonic thymic development. Here we demonstrate that EVA is expressed in choroid plexus from mature immune competent and lymphocyte-deficient (RAG-/-) mice. Choroid plexus epithelial cells from RAG-/- mice demonstrated reduced junctional integrity and enhanced permeability that was associated with decreased expression of E-cadherin and EVA mRNA as compared to wild-type mice.

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Objective: In vitro observations and studies in murine experimental autoimmune encephalomyelitis (EAE) have shown protective effects of sodium channel blockers on central nervous system axons and improved clinical status when treatment is continued throughout the period of observation. Several clinical studies of sodium channel blockers are under way in patients with multiple sclerosis. Here we asked whether a protective effect would persist after withdrawal of a sodium channel blocker.

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Voltage-gated sodium channels expressed on the plasma membrane activate rapidly in response to changes in membrane potential in cells with excitable membranes such as muscle and neurons. Macrophages also require rapid signaling mechanisms as the first line of defense against invasion by microorganisms. In this study, our goal was to examine the role of intracellular voltage-gated sodium channels in macrophage function.

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We here describe a novel CD4 T cell adoptive transfer model of severe experimental autoimmune encephalomyelitis in (C57BL6xB10.PL)F1 mice. This FI cross developed severe disease characterized by extensive parenchymal spinal cord and brain periventricular white matter infiltrates.

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