Hypomyelination, hypodontia and craniofacial abnormalities in a Polr3b mouse model of leukodystrophy.

RNA polymerase III (Pol III)-related hypomyelinating leukodystrophy (POLR3-HLD), also known as 4H leukodystrophy, is a severe neurodegenerative disease characterized by the cardinal features of hypomyelination, hypodontia and hypogonadotropic hypogonadism. POLR3-HLD is caused by biallelic pathogenic variants in genes encoding Pol III subunits. While approximately half of all patients carry mutations in POLR3B encoding the RNA polymerase III subunit B, there is no in vivo model of leukodystrophy based on mutation of this Pol III subunit. Here, we determined the impact of POLR3BΔ10 (Δ10) on Pol III in human cells and developed and characterized an inducible/conditional mouse model of leukodystrophy using the orthologous Δ10 mutation in mice. The molecular mechanism of Pol III dysfunction was determined in human cells by affinity purification-mass spectrometry and western blot. Postnatal induction with tamoxifen induced expression of the orthologous Δ10 hypomorph in triple transgenic Pdgfrα-Cre/ERT; R26-Stopfl-EYFP; Polr3bfl mice. CNS and non-CNS features were characterized using a variety of techniques including microCT, ex vivo MRI, immunofluorescence, immunohistochemistry, spectral confocal reflectance microscopy and western blot. Lineage tracing and time series analysis of oligodendrocyte subpopulation dynamics based on co-labelling with lineage-specific and/or proliferation markers were performed. Proteomics suggested that Δ10 causes a Pol III assembly defect, while western blots demonstrated reduced POLR3BΔ10 expression in the cytoplasm and nucleus in human cells. In mice, postnatal Pdgfrα-dependent expression of the orthologous murine mutant protein resulted in recessive phenotypes including severe hypomyelination leading to ataxia, tremor, seizures and limited survival, as well as hypodontia and craniofacial abnormalities. Hypomyelination was confirmed and characterized using classic methods to quantify myelin components such as myelin basic protein and lipids, results which agreed with those produced using modern methods to quantify myelin based on the physical properties of myelin membranes. Lineage tracing uncovered the underlying mechanism for the hypomyelinating phenotype: defective oligodendrocyte precursor proliferation and differentiation resulted in a failure to produce an adequate number of mature oligodendrocytes during postnatal myelinogenesis. In summary, we characterized the Polr3bΔ10 mutation and developed an animal model that recapitulates features of POLR3-HLD caused by POLR3B mutations, shedding light on disease pathogenesis, and opening the door to the development of therapeutic interventions.

Supporting mental health and psychosocial wellbeing through social and emotional learning: A participatory study of conflict-affected youth resettled to the U.S.

BACKGROUND: A growing literature has drawn attention to the central role that schools play in supporting the adjustment of resettled refugee youth and promoting their mental health and psychosocial wellbeing. In particular, the recent proliferation of school-based social and emotional learning (SEL) initiatives presents an opportunity to strengthen supports for resettled adolescents. This participatory research study aims to understand how high school students resettled from countries in the Middle East and North Africa region are experiencing the challenges and opportunities of acculturation and the ways in which they believe schools can better support them in this process. METHODS: We analyzed primary data collected during focus group discussions as part of the SALaMA study. During these discussions, we used participatory ranking methodology to elicit adolescents' suggestions on how high schools can better support students both academically and psychosocially after resettlement. Fourteen focus group discussions were held with male (n = 38) and female (n = 31) adolescents aged 14-20 years, who were selected purposively across six public high schools in Harrisonburg, Virginia, Austin, Texas, and Detroit, Michigan. Participants offered suggestions and then ranked them in order of importance using consensus ranking. RESULTS: Thematic analysis of the PRM results across sites produced a wealth of suggestions centered around three broad themes, namely: skills related to navigating social and academic challenges, culturally responsive teaching, and socially and culturally equitable learning environments. CONCLUSIONS: Findings reported illustrate limitations of the conventional, universal SEL model and shed light on how schools can adapt transformative SEL strategies to serve their students better, especially newcomers from conflict-affected countries.

SALaMA study protocol: a mixed methods study to explore mental health and psychosocial support for conflict-affected youth in Detroit, Michigan.

BACKGROUND: Families resettling to the U.S. from conflict-affected countries in the Middle East and North Africa (MENA) face countless challenges. These families must cope with experiences of armed conflict and forced migration while also assimilating to a new society. According to the 'immigrant paradox,' time spent in a new country can compound the effects of migration and assimilation challenges and lead to deteriorated mental health. This study aims to assess the psychosocial wellbeing of MENA-born or first-generation adolescents attending school in the Detroit metropolitan area (DMA) to understand how schools, families, and communities play a role in supporting these adolescents' wellbeing. METHODS: The quantitative component of this mixed methods study will involve a self-administered survey with a sample of students whose responses will be linked to academic records and behavioral assessments. The survey will utilize validated instruments to measure depressive and anxiety symptoms (Hopkins Symptom Checklist-37A), hope (Children's Hope Scale), resilience (Child and Youth Resilience Measure-12), externalizing and prosocial behavior (Hopkins Symptom Checklist-37A, Strengths and Difficulties Questionnaire), school belonging (Psychological Sense of School Membership), and peer relationships (Multidimensional Scale of Perceived Social Support). Differences in outcomes will be analyzed across two strata: students born in the MENA region and first-generation students whose parents immigrated to the US from the MENA region. The qualitative component will involve semi-structured key informant interviews with parents, school administrators, educators, and mental health providers, and focus group discussions (FGDs) with a purposive sample of adolescents born - or whose parents were born - in the MENA region. The FGDs will include a participatory ranking activity where participants will be asked to free-list and rank ideas about how schools can better support students like them. Thematic content analysis will be conducted to identify common themes. DISCUSSION: This study will contribute evidence about the wellbeing of adolescents who come from - or whose parents come from - conflict-affected countries currently living in the U.S. Findings can be used to inform program and policy development to enable schools and their community partners to serve this population more effectively.

Perspectives on program mis-implementation among U.S. local public health departments.

BACKGROUND: Public health resources are limited and best used for effective programs. This study explores associations of mis-implementation in public health (ending effective programs or continuing ineffective programs) with organizational supports for evidence-based decision making among U.S. local health departments. METHODS: The national U.S. sample for this cross-sectional study was stratified by local health department jurisdiction population size. One person was invited from each randomly selected local health department: the leader in chronic disease, or the director. Of 600 selected, 579 had valid email addresses; 376 completed the survey (64.9% response). Survey items assessed frequency of and reasons for mis-implementation. Participants indicated agreement with statements on organizational supports for evidence-based decision making (7-point Likert). RESULTS: Thirty percent (30.0%) reported programs often or always ended that should have continued (inappropriate termination); organizational supports for evidence-based decision making were not associated with the frequency of programs ending. The main reason given for inappropriate termination was grant funding ended (86.0%). Fewer (16.4%) reported programs often or always continued that should have ended (inappropriate continuation). Higher perceived organizational supports for evidence-based decision making were associated with less frequent inappropriate continuation (odds ratio = 0.86, 95% confidence interval 0.79, 0.94). All organizational support factors were negatively associated with inappropriate continuation. Top reasons were sustained funding (55.6%) and support from policymakers (34.0%). CONCLUSIONS: Organizational supports for evidence-based decision making may help local health departments avoid continuing programs that should end. Creative mechanisms of support are needed to avoid inappropriate termination. Understanding what influences mis-implementation can help identify supports for de-implementation of ineffective programs so resources can go towards evidence-based programs.

MerTK Is a Functional Regulator of Myelin Phagocytosis by Human Myeloid Cells.

Multifocal inflammatory lesions featuring destruction of lipid-rich myelin are pathologic hallmarks of multiple sclerosis. Lesion activity is assessed by the extent and composition of myelin uptake by myeloid cells present in such lesions. In the inflamed CNS, myeloid cells are comprised of brain-resident microglia, an endogenous cell population, and monocyte-derived macrophages, which infiltrate from the systemic compartment. Using microglia isolated from the adult human brain, we demonstrate that myelin phagocytosis is dependent on the polarization state of the cells. Myelin ingestion is significantly enhanced in cells exposed to TGF-ß compared with resting basal conditions and markedly reduced in classically activated polarized cells. Transcriptional analysis indicated that TGF-ß-treated microglia closely resembled M0 cells. The tyrosine kinase phagocytic receptor MerTK was one of the most upregulated among a select number of differentially expressed genes in TGF-ß-treated microglia. In contrast, MerTK and its known ligands, growth arrest-specific 6 and Protein S, were downregulated in classically activated cells. MerTK expression and myelin phagocytosis were higher in CNS-derived microglia than observed in monocyte-derived macrophages, both basally and under all tested polarization conditions. Specific MerTK inhibitors reduced myelin phagocytosis and the resultant anti-inflammatory biased cytokine responses for both cell types. Defining and modulating the mechanisms that regulate myelin phagocytosis has the potential to impact lesion and disease evolution in multiple sclerosis. Relevant effects would include enhancing myelin clearance, increasing anti-inflammatory molecule production by myeloid cells, and thereby permitting subsequent tissue repair.

Roles of microglia in brain development, tissue maintenance and repair.

The emerging roles of microglia are currently being investigated in the healthy and diseased brain with a growing interest in their diverse functions. In recent years, it has been demonstrated that microglia are not only immunocentric, but also neurobiological and can impact neural development and the maintenance of neuronal cell function in both healthy and pathological contexts. In the disease context, there is widespread consensus that microglia are dynamic cells with a potential to contribute to both central nervous system damage and repair. Indeed, a number of studies have found that microenvironmental conditions can selectively modify unique microglia phenotypes and functions. One novel mechanism that has garnered interest involves the regulation of microglial function by microRNAs, which has therapeutic implications such as enhancing microglia-mediated suppression of brain injury and promoting repair following inflammatory injury. Furthermore, recently published articles have identified molecular signatures of myeloid cells, suggesting that microglia are a distinct cell population compared to other cells of myeloid lineage that access the central nervous system under pathological conditions. Thus, new opportunities exist to help distinguish microglia in the brain and permit the study of their unique functions in health and disease.

Feasibility and acceptability of a timeline follow-back method to assess opioid use, non-fatal overdose, and substance use disorder treatment.

BACKGROUND: Non-fatal overdoses are underreported and there is no accepted and feasible self-report research measure of non-fatal opioid overdose. Timeline follow-back (TLFB) calendar-based questionnaires assess self-reported risk behaviors. We assessed feasibility and acceptability of a new TLFB research measure for opioid use, non-fatal opioid overdose, and substance use disorder treatment among opioid overdose survivors. METHODS: For the Repeated-dose Behavioral Intervention to Reduce Opioid Overdose Trial (REBOOT) study among opioid overdose survivors, we developed a TLFB questionnaire to assess daily non-prescribed opioid use, opioid overdose, facility stays, medications/behavioral treatment for opioid use disorder, and COVID-19 history during the previous 120 days. Staff assessors administered TLFB at four-monthly visits over the 16-month study participation period. To measure feasibility, we estimated TLFB completion time using an electronic timestamp tool. To measure acceptability, we administered a satisfaction survey to 103 participants who completed REBOOT. RESULTS: Among 525 TLFB assessments conducted in 174 participants from January 2021-January 2023, opioid use was reported in 510 assessments, medication for opioid use disorder (MOUD) in 331 assessments, and ≥ 1 overdose in 107 assessments. Median TLFB completion time was 11 (IQR: 6-17) minutes for sections administered to all participants; detailed overdose questions administered to those reporting overdose took an additional 3 (IQR: 2-6) minutes. Report of ≥ 1 overdose and MOUD use were significantly associated with increased TLFB completion time. 88 % of participants reported that TLFB was very/somewhat acceptable. CONCLUSIONS: Among opioid overdose survivors, REBOOT TLFB was a feasible and acceptable research measure, with similar completion time as other TLFB assessments of substance use.

Decreased RNA polymerase III subunit expression leads to defects in oligodendrocyte development.

Introduction: RNA polymerase III (Pol III) is a critical enzymatic complex tasked with the transcription of ubiquitous non-coding RNAs including 5S rRNA and all tRNA genes. Despite the constitutive nature of this enzyme, hypomorphic biallelic pathogenic variants in genes encoding subunits of Pol III lead to tissue-specific features and cause a hypomyelinating leukodystrophy, characterized by a severe and permanent deficit in myelin. The pathophysiological mechanisms in POLR3- related leukodystrophy and specifically, how reduced Pol III function impacts oligodendrocyte development to account for the devastating hypomyelination seen in the disease, remain poorly understood. Methods: In this study, we characterize how reducing endogenous transcript levels of leukodystrophy-associated Pol III subunits affects oligodendrocyte maturation at the level of their migration, proliferation, differentiation, and myelination. Results: Our results show that decreasing Pol III expression altered the proliferation rate of oligodendrocyte precursor cells but had no impact on migration. Additionally, reducing Pol III activity impaired the differentiation of these precursor cells into mature oligodendrocytes, evident at both the level of OL-lineage marker expression and on morphological assessment, with Pol III knockdown cells displaying a drastically more immature branching complexity. Myelination was hindered in the Pol III knockdown cells, as determined in both organotypic shiverer slice cultures and co-cultures with nanofibers. Analysis of Pol III transcriptional activity revealed a decrease in the expression of distinct tRNAs, which was significant in the siPolr3a condition. Discussion: In turn, our findings provide insight into the role of Pol III in oligodendrocyte development and shed light on the pathophysiological mechanisms of hypomyelination in POLR3-related leukodystrophy.

An optimized and validated protocol for the purification of PDGFRα+ oligodendrocyte precursor cells from mouse brain tissue via immunopanning.

Immunopanning is an efficient and reliable method for isolating primary cells from rodent brain tissue, making it a valuable tool for researchers interested in in vitro glial models. Here, we present an immunopanning protocol optimized for the isolation of Platelet-Derived Growth Factor Receptor Alpha positive (PDGFRα+) oligodendrocyte precursor cells (OPCs) from mouse brain tissue that results in a high yield of pure OPCs from minimal quantities of starting tissue.•The protocol presented here is optimized for a PDGFRα-dependent selection of mouse OPCs using a commercial antibody, accounting for the relatively weaker adhesion of OPCs to the anti-PDGFRα plate as compared to other oligodendrocyte lineage markers (e.g., MOG).•A modified papain digestion step, with 95% O2/5% CO2 gas that is humidified prior to perfusion, significantly enhances the yield of dissociated cells and final yield of OPCs.•Isolating OPCs at the PDGFRα+ stage permits the expansion of cells in culture, facilitating studies using transgenic mice, and enables studies on the development of the oligodendrocyte lineage without the spatial and temporal complexity of in vivo studies.

Solving inherited white matter disorder etiologies in the neurology clinic: Challenges and lessons learned using next-generation sequencing.

Introduction: Rare neurodevelopmental disorders, including inherited white matter disorders or leukodystrophies, often present a diagnostic challenge on a genetic level given the large number of causal genes associated with a range of disease subtypes. This study aims to demonstrate the challenges and lessons learned in the genetic investigations of leukodystrophies through presentation of a series of cases solved using exome or genome sequencing. Methods: Each of the six patients had a leukodystrophy associated with hypomyelination or delayed myelination on MRI, and inconclusive clinical diagnostic genetic testing results. We performed next generation sequencing (case-based exome or genome sequencing) to further investigate the genetic cause of disease. Results: Following different lines of investigation, molecular diagnoses were obtained for each case, with patients harboring pathogenic variants in a range of genes including TMEM106B, GJA1, AGA, POLR3A, and TUBB4A. We describe the lessons learned in reaching the genetic diagnosis, including the importance of (a) utilizing proper multi-gene panels in clinical testing, (b) assessing the reliability of biochemical assays in supporting diagnoses, and (c) understanding the limitations of exome sequencing methods in regard to CNV detection and region coverage in GC-rich areas. Discussion: This study illustrates the importance of applying a collaborative diagnostic approach by combining detailed phenotyping data and metabolic results from the clinical environment with advanced next generation sequencing analysis techniques from the research environment to increase the diagnostic yield in patients with genetically unresolved leukodystrophies.

The Effectiveness of Women and Girls Safe Spaces: A Systematic Review of Evidence to Address Violence Against Women and Girls in Humanitarian Contexts.

One in three women and girls will experience violence in their lifetime. In conflict and postconflict settings, the incidence of violence against women and girls (VAWG) is exacerbated, resulting in increased negative social, economic, health, and psychosocial effects. In an attempt to prevent and respond to the occurrence of VAWG in humanitarian settings, Women and Girls Safe Spaces (WGSS) have been promoted as a promising intervention. The authors conducted a systematic review to examine the current quantitative evidence available on the impact and effectiveness of WGSS programs. The authors reviewed relevant peer-reviewed and gray literature using predefined search terms for potential inclusion. Seven records met inclusion criteria. Records included evaluations of WGSS programs implemented in the Democratic Republic of the Congo, Ethiopia, Uganda, Tanzania, Kenya, Bangladesh, and Pakistan. While none of the studies reported reductions in exposure to or incidence of VAWG among program participants, three evaluations demonstrated moderate improvements in psychosocial well-being, social support, and attitudes toward rites of passage. Additionally, only three of the seven evaluations employed rigorous methodologies. This study illustrates the paucity of existing quantitative evidence around the impact of WGSS and the need for further research examining the potential benefits of this widely implemented intervention for women and girls. A stronger evidence base has the potential to inform policy and program development and to help governments, organizations, and communities better allocate limited resources in response to VAWG.

Discovery of Phospholipase D Inhibitors with Improved Drug-like Properties and Central Nervous System Penetrance.

Phospholipase D (PLD) is a phospholipase enzyme responsible for hydrolyzing phosphatidylcholine into the lipid signaling molecule, phosphatidic acid, and choline. From a therapeutic perspective, PLD has been implicated in human cancer progression as well as a target for neurodegenerative diseases, including Alzheimer's. Moreover, knockdown of PLD rescues the ALS phenotype in multiple Drosophila models of ALS (amyotrophic lateral sclerosis) and displays modest motor benefits in an SOD1 ALS mouse model. To further validate whether inhibiting PLD is beneficial for the treatment of ALS, a brain penetrant small molecule inhibitor with suitable PK properties to test in an ALS animal model is needed. Using a combination of ligand-based drug discovery and structure-based design, a dual PLD1/PLD2 inhibitor was discovered that is single digit nanomolar in the Calu-1 cell assay and has suitable PK properties for in vivo studies. To capture the in vivo measurement of PLD inhibition, a transphosphatidylation pharmacodynamic LC-MS assay was developed, in which a dual PLD1/PLD2 inhibitor was found to reduce PLD activity by 15-20-fold.

Psychosocial Well-Being, Mental Health, and Available Supports in an Arab Enclave: Exploring Outcomes for Foreign-Born and U.S.-Born Adolescents.

Introduction: Few studies have assessed the impact of displacement, resettlement, and discrimination on well-being outcomes for adolescent refugees resettled within the U.S. Conducted in three charter schools in the intergenerational Arab enclave of the Detroit Metropolitan Area, this mixed-methods study assessed the mental health and psychosocial support for both U.S.- and foreign-born adolescents from the Middle East and North Africa region. Methods: A quantitative survey was used to collect data on 176 students. Key outcomes included hope, prosocial behaviors, resilience, depressive, anxiety, externalizing symptoms, stressful life events, perceived social support, and sense of school belonging. Differences in outcomes between U.S.- and foreign-born students were compared using T-tests. Regression analysis explored whether outcomes were gendered and correlated with years in the U.S. for foreign-born students. Qualitative data collection included key informant interviews with school staff and community service providers, student focus group discussions, and caregiver interviews. Interview transcripts were analyzed using thematic analysis and the constant comparative method. Results: No statistically significant differences between the foreign-born and U.S.-born groups were observed. However, analysis revealed that resilience decreased for male students with time spent in the U.S. Qualitative themes illuminated these results; shared cultural heritage allowed newcomer students to access relevant language and psychosocial support, while inter- and intra-group peer relationships strengthened students' dual language skills and identity formation. However, shifting gender expectations and role hierarchies for newcomer students revealed boys' increased stressors in the family domain and girls' better accessed support in the school context. Conclusion: The existence of an immigrant paradox in this enclave setting was not supported. Instead, findings highlight the reciprocal value of peer-based mentorships and friendships between U.S.- and foreign-born students with similar cultural backgrounds, the importance of social and emotional curricula and cultural competency training within schools, and the gendered effects of acculturation.

POLR3-Related Leukodystrophy: Exploring Potential Therapeutic Approaches.

Leukodystrophies are a class of rare inherited central nervous system (CNS) disorders that affect the white matter of the brain, typically leading to progressive neurodegeneration and early death. Hypomyelinating leukodystrophies are characterized by the abnormal formation of the myelin sheath during development. POLR3-related or 4H (hypomyelination, hypodontia, and hypogonadotropic hypogonadism) leukodystrophy is one of the most common types of hypomyelinating leukodystrophy for which no curative treatment or disease-modifying therapy is available. This review aims to describe potential therapies that could be further studied for effectiveness in pre-clinical studies, for an eventual translation to the clinic to treat the neurological manifestations associated with POLR3-related leukodystrophy. Here, we discuss the therapeutic approaches that have shown promise in other leukodystrophies, as well as other genetic diseases, and consider their use in treating POLR3-related leukodystrophy. More specifically, we explore the approaches of using stem cell transplantation, gene replacement therapy, and gene editing as potential treatment options, and discuss their possible benefits and limitations as future therapeutic directions.

Expanding the phenotypic and molecular spectrum of RNA polymerase III-related leukodystrophy.

OBJECTIVE: To expand the phenotypic spectrum of severity of POLR3-related leukodystrophy and identify genotype-phenotype correlations through study of patients with extremely severe phenotypes. METHODS: We performed an international cross-sectional study on patients with genetically proven POLR3-related leukodystrophy and atypical phenotypes to identify 6 children, 3 males and 3 females, with an extremely severe phenotype compared with that typically reported. Clinical, radiologic, and molecular features were evaluated for all patients, and functional and neuropathologic studies were performed on 1 patient. RESULTS: Each patient presented between 1 and 3 months of age with failure to thrive, severe dysphagia, and developmental delay. Four of the 6 children died before age 3 years. MRI of all patients revealed a novel pattern with atypical characteristics, including progressive basal ganglia and thalami abnormalities. Neuropathologic studies revealed patchy areas of decreased myelin in the cerebral hemispheres, cerebellum, brainstem, and spinal cord, with astrocytic gliosis in the white matter and microglial activation. Cellular vacuolization was observed in the thalamus and basal ganglia, and neuronal loss was evident in the putamen and caudate. Genotypic similarities were also present between all 6 patients, with one allele containing a POLR3A variant causing a premature stop codon and the other containing a specific intronic splicing variant (c.1771-7C>G), which produces 2 aberrant transcripts along with some wild-type transcript. CONCLUSIONS: We describe genotype-phenotype correlations at the extreme end of severity of the POLR3-related leukodystrophy spectrum and shed light on the complex disease pathophysiology.

Local Health Department Accreditation Is Associated With Organizational Supports for Evidence-Based Decision Making.

Introduction: Recent studies show that health department accreditation from the U.S. Public Health Accreditation Board (PHAB) drives performance management and quality improvement. PHAB standards call for agencies to use evidence in decision making. It is unknown whether accreditation is associated with organizational supports for evidence-based decision making (EBDM). Self-report data from a 2017 survey of U.S. local health departments were analyzed to test relationships of accreditation status with organizational supports for EBDM. Methods: A cross-sectional survey was conducted in this observational study. A total of 579 local health departments were invited to complete an online survey; 350 (60.4%) provided complete data for the present study. The dependent variables were six factors of organizational supports for EBDM previously validated through confirmatory factor analyses. Accreditation status (PHAB-accredited, preparing, not preparing) was the independent variable of interest. Logistic regression analyses controlled for governance (presence of a local board of health; state, local, or shared state and local governance) and jurisdiction population size. Results: PHAB-accredited health departments were more likely to report higher capacity for EBDM, resource availability for EBDM, and evaluation capacity than health departments that reported not yet preparing for accreditation. Health departments that reported preparing for PHAB accreditation showed a non-significant pattern of higher perceived supports for EBDM compared to departments not preparing for accreditation. Conclusion: PHAB standards and the accreditation process may help stimulate health department organizational supports for EBDM.

Effects of fumarates on circulating and CNS myeloid cells in multiple sclerosis.

OBJECTIVE: Dimethyl fumarate (DMF), a therapy for relapsing-remitting multiple sclerosis (RRMS), is implicated as acting on inflammatory and antioxidant responses within both systemic immune and/or central nervous system (CNS) compartments. Orally administered DMF is rapidly metabolized to monomethyl fumarate (MMF). Our aim was to analyze the impact of fumarates on antiinflammatory and antioxidant profiles of human myeloid cells found in the systemic compartment (monocytes) and in the inflamed CNS (blood-derived macrophages and brain-derived microglia). METHODS: We analyzed cytokine and antioxidant expression in monocytes from untreated or DMF-treated RRMS patients and controls, and in monocyte-derived macrophages (MDMs) and microglia isolated from adult and fetal human brain tissue. RESULTS: Monocytes from multiple sclerosis (MS) patients receiving DMF had reduced expression of the proinflammatory micro-RNA miR-155 and of antioxidant genes HMOX1 and OSGIN1 compared to untreated MS patients; similar changes were observed in patients receiving FTY720 and/or natalizumab. In vitro addition of DMF but not MMF to MDMs and microglia inhibited lipopolysaccharide-induced production of inflammatory cytokines and increased expression of the antioxidant gene HMOX1 in the absence of significant cytotoxicity. INTERPRETATION: Our in vivo-based observations that effects of DMF therapy on systemic myeloid cell gene expression are also observed with FTY720 and natalizumab therapy suggests that the effect may be indirect, reflecting reduced overall disease activity. Our in vitro results demonstrate significant effects of DMF but not MMF on inflammation and antioxidant responses by MDMs and microglia, questioning the mechanisms whereby DMF therapy would modulate myeloid cell properties within the CNS.