Novel multiple sclerosis susceptibility loci implicated in epigenetic regulation

We conducted a genome-wide association study (GWAS) on multiple sclerosis (MS) susceptibility in German cohorts with 4888 cases and 10,395 controls. In addition to associations within the major histocompatibility complex (MHC) region, 15 non-MHC loci reached genome-wide significance. Four of these loci are novel MS susceptibility loci. They map to the genes L3MBTL3, MAZ, ERG, and SHMT1. The lead variant at SHMT1 was replicated in an independent Sardinian cohort. Products of the genes L3MBTL3, MAZ, and ERG play important roles in immune cell regulation. SHMT1 encodes a serine hydroxymethyltransferase catalyzing the transfer of a carbon unit to the folate cycle. This reaction is required for regulation of methylation homeostasis, which is important for establishment and maintenance of epigenetic signatures. Our GWAS approach in a defined population with limited genetic substructure detected associations not found in larger, more heterogeneous cohorts, thus providing new clues regarding MS pathogenesis

Continuous short-term structural network reorganisation beyond atrophy in patients with RRMS [Abstract]

Background and aim: Longitudinal assessment of structural brain changes is important to track the clinical course of multiple sclerosis (MS), but an exact quantification of the diffuse tissue damage is highly challenging. We aimed to identify short-term structural dynamics by measuring grey matter (GM) network connectivity patterns and comparing these with established morphological measures of GM integrity. Methods: For our prospectively designed study, we collected data from January 2013 through December 2014. In total, forty-five structural MRI datasets from relapsing-remitting MS patients in the relapse free phase of the disease (mean age: 42 ± 12.1 years; median EDSS 1.5 (0 - 2.5); mean disease duration 3.5 ± 6.5 years) were acquired using 3T MRI. Each patient was followed up every 8 weeks for 8 months and all patients were enrolled at two German university hospitals. Longitudinal brain atrophy was analyzed using SIENA (part of FSL), while FreeSurfer was used to investigate cortical thickness changes over time. GM connectivity patterns were reconstructed from cortical thickness correlation matrix between anatomical regions, as derived from the AAL atlas, and a network analysis was conducted using graph theoretical approaches. Results: Our study shows a significant longitudinal structural network reorganisation in the absence of cortical thinning and brain atrophy already over a period of 4 months. We demonstrate an increased local (clustering coefficient (F(4,41) = 3.547, p < 0.001), local efficiency (F(4,41) = 3.0874, p < 0.01)) and modular connectivity pattern (modularity (F(4,41) =2.612, p < 0.01)). Conversely a concomitant break-down of long-range connectivity occurred (assortativity (F(4,41) = 3.0654, p < 0.01) and small-world index (F(4,41) = 3.687, p < 0.001)). No regional or global atrophy signs were detected in the applied morphometric analysis. Conclusions and relevance: Our GM network analysis demonstrates a short-term increase in local connectivity and a decrease in long-range paths in MS patients in the relapse free state of the disease, in the absence of atrophy or clinical progression. Structural reorganisation patterns with co-occurrence of detrimental and adaptive reorganisation processes might be important sensitive measurable fingerprints of the disease that can be used in clinical practice

Longitudinal structural network reorganisation in early relapsing-remitting multiple sclerosis [Abstract]

Background: Multiple sclerosis (MS) is characterized by relapses and remissions indicating damage and compensatory processes occurring early in the disease. Over time, cortical pathology is highly relevant for disability, while brain networks evolve towards a disconnected organization as the disease progresses. However, it is poorly understood how and when pathology impacts cortical networks and in particular, how the network responds to damage in the very beginning of the disease. Aim: To address cortical pathology by quantifying structural connectivity patterns over 12 months in patients with early relapsing-remitting MS. Methods: Here we investigated cortical grey matter networks longitudinally as derived from structural 3 Tesla MRI in 92 patients in the initial phase of the disease (65 female / 27 male; mean age: 32.9 ± 9.9 years; mean disease duration: 12.1 ± 14.5 months) and in 101 healthy controls (59 female / 42 male; mean age: 19.7 ± 0.9 years). Longitudinal brain volume atrophy was analyzed using SIENA and cortical thickness changes were quantified using FreeSurfer. Brain networks were computed based on cortical thickness inter-regional correlations between anatomical regions and fed into graph theoretical analysis. Finally, subgroup analyses were performed between patients with “no evidence of disease activity” (NEDA) during this period and those with disease activity (EDA). Results: Over one year, increased local cortical connectivity and an emerging modular-constructed network were detected in patients - a pattern reported to be associated with adaptation, efficiency and compensation. These longitudinal dynamics were attested in both patients with NEDA and EDA, indicating continuous cortical reorganisation independent of disease activity. This local and modular cortical reorganisation was not detected in healthy controls over the same period of time and emerged beyond measureable signs of atrophy using established morphometric tools. Conclusion: Our findings demonstrate that despite initiation of neuroinflammatory damage, substantial structural adaptation processes emerge cortically in the early disease stage. This subtle reorganisation of the cortex architecture is quantifiable by structural MRI in patients with and without disease activity, suggesting a principal response of the network evolving from the onset of this chronic disease. Disclosure: The authors declare no conflict of interests

Modulation of Calcium-Dependent Inactivation of L-Type Ca2+ Channels via β-Adrenergic Signaling in Thalamocortical Relay Neurons

Neuronal high-voltage-activated (HVA) Ca2+ channels are rapidly inactivated by a mechanism that is termed Ca2+-dependent inactivation (CDI). In this study we have shown that β-adrenergic receptor (βAR) stimulation inhibits CDI in rat thalamocortical (TC) relay neurons. This effect can be blocked by inhibition of cAMP-dependent protein kinase (PKA) with a cell-permeable inhibitor (myristoylated protein kinase inhibitor-(14–22)-amide) or A-kinase anchor protein (AKAP) St-Ht31 inhibitory peptide, suggesting a critical role of these molecules downstream of the receptor. Moreover, inhibition of protein phosphatases (PP) with okadaic acid revealed the involvement of phosphorylation events in modulation of CDI after βAR stimulation. Double fluorescence immunocytochemistry and pull down experiments further support the idea that modulation of CDI in TC neurons via βAR stimulation requires a protein complex consisting of CaV1.2, PKA and proteins from the AKAP family. All together our data suggest that AKAPs mediate targeting of PKA to L-type Ca2+ channels allowing their phosphorylation and thereby modulation of CDI

Continuous reorganisation of cortical information flow in MS patients: a longitudinal effective connectivity study [Abstract]

Background: Brain reorganisation processes are essential for the long-term outcome in patients with multiple sclerosis (MS). Effective connectivity (EC) as derived from functional MRI, can be analysed to estimate reorganisation processes and directional information flows between cortical regions. These measures could provide the missing link for modelling the long-term disease course between tissue damage and repair or adaptation. Aim: To obtain longitudinal measurements of EC and information flows in MS patients at short-term intervals focusing on the main anatomical brain regions and to investigate the link between the connectivity strength and clinical impairment. Methods: Twelve MS patients (mean age: 41.7 ± 11.5 years) underwent 3 Tesla structural and resting state functional MRI at five different time points over one year (approximately every 12 weeks). Twelve healthy subjects (mean age: 33.5 ± 9.6 years) served as controls (HC). For the analytical framework, two novel approaches for EC quantification were used. Causal Bayesian Network (CBN) and Time Domain Partial Directed Coherence (TPDC) were applied for the description of the information flows between frontal, prefrontal, temporal, occipital, and parietal lobe; cerebellum and deep grey matter nuclei (DGMN) were also analysed. Results: Specific longitudinal EC patterns have been attested in the studied regions. Information flows from DGMN, frontal, prefrontal and temporal to the other studied regions showed a continuous increase over time, whereas the directed connections from parietal and occipital lobes and from the cerebellum did not change over time as confirmed by both applied methods. No longitudinal changes of EC were attested in HC. The longitudinal connectivity increase in the prefrontal-frontal and fronto-cerebellar pathway showed a significant inverse correlation to EDSS (Expanded Disability Status Scale). Moreover, the EC change from the frontal lobe to the cerebellum showed a significant inverse correlation to patients’ fatigue score. Conclusion: Our data depicts a continuous longitudinal increase in EC in patients with MS substantiated by two novel methodological approaches. Furthermore, the dynamics of the fronto-cerebellar connections are linked to clinical impairment and possibly essential for the long-term outcome

HDAC inhibitor confers radiosensitivity to prostate stem-like cells

Background: Radiotherapy can be an effective treatment for prostate cancer, but radiorecurrent tumours do develop. Considering prostate cancer heterogeneity, we hypothesised that primitive stem-like cells may constitute the radiation-resistant fraction. Methods: Primary cultures were derived from patients undergoing resection for prostate cancer or benign prostatic hyperplasia. After short-term culture, three populations of cells were sorted, reflecting the prostate epithelial hierarchy, namely stem-like cells (SCs, α2β1integrinhi/CD133+), transit-amplifying (TA, α2β1integrinhi/CD133−) and committed basal (CB, α2β1integrinlo) cells. Radiosensitivity was measured by colony-forming efficiency (CFE) and DNA damage by comet assay and DNA damage foci quantification. Immunofluorescence and flow cytometry were used to measure heterochromatin. The HDAC (histone deacetylase) inhibitor Trichostatin A was used as a radiosensitiser. Results: Stem-like cells had increased CFE post irradiation compared with the more differentiated cells (TA and CB). The SC population sustained fewer lethal double-strand breaks than either TA or CB cells, which correlated with SCs being less proliferative and having increased levels of heterochromatin. Finally, treatment with an HDAC inhibitor sensitised the SCs to radiation. Interpretation: Prostate SCs are more radioresistant than more differentiated cell populations. We suggest that the primitive cells survive radiation therapy and that pre-treatment with HDAC inhibitors may sensitise this resistant fraction

High socioeconomic impact on prescription behavior despite unrestricted access to disease-modifying therapies in people with multiple sclerosis

BACKGROUND: Economic and health care restraints strongly impact on drug prescription for chronic diseases. We aimed to identify potential factors for prescription behavior in chronic disease. Multiple sclerosis was chosen as a model disease due to its chronic character, incidence, and high socioeconomic impact. METHODS: Germany was used as a model country as the health-care system is devoid of economic and drug availability restraints. German statutory health insurance data were analyzed retrospectively. The impact of number of university hospitals and neurologists as well as the gross domestic product (GDP) as potential factors on prescriptions of platform and high-efficacy disease-modifying therapies (DMTs) was analyzed. RESULTS: Prescription of platform DMTs increased over time in almost all federal states with varying degree of increase. Univariate regression analysis showed that the prescription volume of platform DMTs positively correlated with the number of university hospitals and neurologists, as well as the GDP per federal state. Stepwise forward regression analysis including all potential factors indicated a statistically significant model for platform DMT (R(2) = 0.55; 95%-CI [0.28, 0.82]; p=0.001) revealing GDP as the main contributor. This was confirmed in the independent analysis. CONCLUSION: This study illustrates that even without overt drug prescription inequity, access to medication is not evenly distributed and depends on economic strength and regional medical care density

Immune system activation and cognitive impairment in arterial hypertension

Chronic arterial hypertension disrupts the integrity of the cerebral microvasculature, doubling the risk of age-related dementia. Despite sufficient antihypertensive therapy in still a significant proportion of individuals blood pressure lowering alone does not preserve cognitive health. Accumulating evidence highlights the role of inflammatory mechanisms in the pathogenesis of hypertension. In this review, we introduce a temporal framework to explore how early immune system activation and interactions at neurovascular-immune interfaces pave the way to cognitive impairment. The overall paradigm suggests that prohypertensive stimuli induce mechanical stress and systemic inflammatory responses that shift peripheral and meningeal immune effector mechanisms toward a proinflammatory state. Neurovascular-immune interfaces in the brain include a dysfunctional blood-brain barrier, crossed by peripheral immune cells; the perivascular space, in which macrophages respond to cerebrospinal fluid- and blood-derived immune regulators; and the meningeal immune reservoir, particularly T cells. Immune responses at these interfaces bridge peripheral and neurovascular unit inflammation, directly contributing to impaired brain perfusion, clearance of toxic metabolites, and synaptic function. We propose that deep immunophenotyping in biofluids together with advanced neuroimaging could aid in the translational determination of sequential immune and brain endotypes specific to arterial hypertension. This could close knowledge gaps on how and when immune system activation transits into neurovascular dysfunction and cognitive impairment. In the future, targeting specific immune mechanisms could prevent and halt hypertension disease progression before clinical symptoms arise, addressing the need for new interventions against one of the leading threats to cognitive health

CD4+ CD25+ FoxP3+ regulatory T cells suppress cytotoxicity of CD8+ effector T cells: implications for their capacity to limit inflammatory central nervous system damage at the parenchymal level

<p>Abstract</p> <p>Background</p> <p>CD4⁺CD25⁺forkhead box P3 (FoxP3)⁺regulatory T cells (T reg cells) are known to suppress adaptive immune responses, key control tolerance and autoimmunity.</p> <p>Methods</p> <p>We challenged the role of CD4⁺T reg cells in suppressing established CD8⁺T effector cell responses by using the OT-I/II system <it>in vitro </it>and an OT-I-mediated, oligodendrocyte directed <it>ex vivo </it>model (ODC-OVA model).</p> <p>Results</p> <p>CD4⁺T reg cells dampened cytotoxicity of an ongoing CD8⁺T effector cell attack <it>in vitro </it>and within intact central nervous system tissue <it>ex vivo</it>. However, their suppressive effect was limited by the strength of the antigen signal delivered to the CD8⁺T effector cells and the ratio of regulatory to effector T cells. CD8⁺T effector cell suppression required T cell receptor-mediated activation together with costimulation of CD4⁺T reg cells, but following activation, suppression did not require restimulation and was antigen non-specific.</p> <p>Conclusions</p> <p>Our results suggest that CD4⁺T reg cells are capable of suppressing CD8⁺T effector cell responses at the parenchymal site, that is, limiting parenchymal damage in autoimmune central nervous system inflammation.</p

Altered grey matter networks in young patients with MS at genetic risk for Alzheimer's disease [Abstract]

Background: The Apolipoprotein E (APOE) ε4 is the major susceptibility factor for cognitive impairment and Alzheimer’s disease. Cognitive decline is also a concern in patients with multiple sclerosis (MS). Whether APOE ε4 exerts an effect on brain structure and grey matter (GM) networks in MS patients that could potentiate the long-term cognitive disabilities is unclear. Moreover the description of the exact link between genetic markers and MR driven measures of brain integrity are of essential importance to study cognition in patients with MS and for interventions to prevent longitudinal deterioration. Methods: MS Patients with no immunomodulatory treatment were enrolled in the “Krankheitsbezogene Kompetenznetz Multiple Sclerosis (KKNMS)”. From this multicenter dataset 37 heterozygous APOE ε4 carriers (i.e. having the genotype ε3/ε4) and 37 non-carriers (ε3/ε3) were matched for demographics (mean age: 38.4±9.2 yrs, mean EDSS 1.23±0.99) from one site. A replication study was performed in a cohort (n=46) from a second site. Cortical thickness (CT) was derived from 3T MRI using FreeSurfer. GM connectivity networks were reconstructed from the CT correlation between the 68 regions of the Desikan-Killiany atlas. Cortical integrity and network connectivity -derived from graph theoretical approaches- were compared between the groups in both cohorts. Results corrected for multiple comparisons were considered (p< 0.05 FDR). Results: No regional or global cortical atrophy differences were attested between the two groups in both cohorts. In the network connectivity analysis a decreased local connectivity pattern (reduced transitivity, t=-3.24 p=0.008) was evident in APOE ε4 carriers. Regions with decreased connectivity were consistently seen in the medial part of the left temporal lobe. APOE ε4 status was further associated with raised whole brain connectivity, reflected by increased global efficiency (t=4.34 p=0.005) and reduced modularity (t=-2.84 p=0.02). This network pattern was shown in the frontal, parietal and lateral temporal associative cortices. The results were entirely replicated in the second cohort. Conclusion: We found that MS patients at genetic risk for cognitive decline have significant abnormalities of local GM networks and possibly compensatory increased long-range connectivity patterns. Chronic or focal neuroinflammation could lead to behaviourally relevant memory impairments in these patients through a specific break-down of the long-range paths