Multiple sclerosis and drug discovery:A work of translation

Multiple sclerosis (MS) is after trauma the most important neurological disease in young adults, affecting 1 per 1000 individuals. With currently available medications, most of these targeting the immune system, satisfactory results have been obtained in patients with relapsing MS, but these can have serious adverse effects. Moreover, despite some promising developments, such as with B cell targeting therapies or sphingosine-1-phosphate modulating drugs, there still is a high unmet need of safe drugs with broad efficacy in patients with progressive MS. Despite substantial investments and intensive preclinical research, the proportion of promising lead compounds that reaches the approved drug status remains disappointingly low. One cause lies in the poor predictive validity of MS animal models used in the translation of pathogenic mechanisms into safe and effective treatments for the patient. This disturbing situation has raised criticism against the relevance of animal models used in preclinical research and calls for improvement of these models. This publication presents a potentially useful strategy to enhance the predictive validity of MS animal models, namely, to analyze the causes of failure in forward translation (lab to clinic) via reverse translation (clinic to lab). Through this strategy new insights can be gained that can help generate more valid MS models

Marathon performance but not BMI affects post-marathon pro-inflammatory and cartilage biomarkers

We tested the hypothesis that changes in serum cartilage oligomeric matrix protein (COMP), tumour necrosis factor α (TNF-α), interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) concentration after regular endurance training and running a marathon race depend on body mass index (BMI) and/or on marathon performance. Blood samples were collected from 45 runners of varying BMI and running experience before and after a 10-week marathon training programme and before, immediately and 24 h after a marathon race. Serum biomarker concentrations, BMI and marathon finishing time were measured. The mean (95% confidence interval (CI)) changes from before to immediately after the marathon were COMP: 4.09 U/L (3.39-4.79 U/L); TNF-α: -1.17 mg/L (-2.58 to 0.25 mg/L); IL-6: 12.0 pg/mL (11.4-12.5 pg/mL); and hsCRP: -0.08 pg/mL (-0.14 to -0.3 pg/mL). The mean (95% CI) changes from immediately after to 24 h after the marathon were COMP: 0.35 U/L (-0.88 to 1.57 U/L); TNF-α: -0.43 mg/L (-0.99 to 0.13 mg/L); IL-6: -9.9 pg/mL (-10.5 to -9.4 pg/mL); and hsCRP: 1.52 pg/mL (1.25-1.79 pg/mL). BMI did not affect changes in biomarker concentrations. Differences in marathon finishing time explained 32% of variability in changes in serum hsCRP and 28% of variability in changes in serum COMP during the 24 h recovery after the marathon race (P < 0.001). Slower marathon finishing time but not a higher BMI modulates increases in pro-inflammatory markers or cartilage markers following a marathon race

Table of Contents

Table of contents for Volume 10, Issue 3 of the Linfield Magazin

Mechanistic underpinning of an inside–out concept for autoimmunity in multiple sclerosis

The neuroinflammatory disease multiple sclerosis is driven by autoimmune pathology in the central nervous system. However, the trigger of the autoimmune pathogenic process is unknown. MS models in immunologically naïve, specific‐pathogen‐free bred rodents support an exogenous trigger, such as an infection. The validity of this outside–in pathogenic concept for MS has been frequently challenged by the difficulty to translate pathogenic concepts developed in these models into effective therapies for the MS patient. Studies in well‐validated non‐human primate multiple sclerosis models where, just like in humans, the autoimmune pathogenic process develops from an experienced immune system trained by prior infections, rather support an endogenous trigger. Data reviewed here corroborate the validity of this inside–out pathogenic concept for multiple sclerosis. They also provide a plausible sequence of events reminiscent of Wilkin’s primary lesion theory: (i) that autoimmunity is a physiological response of the immune system against excess antigen turnover in diseased tissue (the primary lesion) and (ii) that individuals developing autoimmune disease are (genetically predisposed) high responders against critical antigens. Data obtained in multiple sclerosis brains reveal the presence in normally appearing white matter of myelinated axons where myelin sheaths have locally dissociated from their enwrapped axon (i.e., blistering). The ensuing disintegration of axon–myelin units potentially causes the excess systemic release of post‐translationally modified myelin. Data obtained in a unique primate multiple sclerosis model revealed a core pathogenic role of T cells present in the normal repertoire, which hyper‐react to post‐translationally modified (citrullinated) myelin–oligodendrocyte glycoprotein and evoke clinical and pathological aspects of multiple sclerosis

Comparative analysis of bone structural parameters reveals subchondral cortical plate resorption and increased trabecular bone remodeling in human facet joint osteoarthritis

Facet joint osteoarthritis is a prominent feature of degenerative spine disorders, highly prevalent in ageing populations, and considered a major cause for chronic lower back pain. Since there is no targeted pharmacological therapy, clinical management of disease includes analgesic or surgical treatment. The specific cellular, molecular, and structural changes underpinning facet joint osteoarthritis remain largely elusive. The aim of this study was to determine osteoarthritis-related structural alterations in cortical and trabecular subchondral bone compartments. To this end, we conducted comparative micro computed tomography analysis in healthy (n = 15) and osteoarthritic (n = 22) lumbar facet joints. In osteoarthritic joints, subchondral cortical plate thickness and porosity were significantly reduced. The trabecular compartment displayed a 42 percent increase in bone volume fraction due to an increase in trabecular number, but not trabecular thickness. Bone structural alterations were associated with radiological osteoarthritis severity, mildly age-dependent but not gender-dependent. There was a lack of association between structural parameters of cortical and trabecular compartments in healthy and osteoarthritic specimens. The specific structural alterations suggest elevated subchondral bone resorption and turnover as a potential treatment target in facet joint osteoarthritis

Multi-contrast, isotropic, single-slab 3D MR imaging in multiple sclerosis

To describe signal and contrast properties of an isotropic, single-slab 3D dataset [double inversion- recovery (DIR), fluid-attenuated inversion recovery (FLAIR), T2, and T1-weighted magnetization prepared rapid acquisition gradient-echo (MPRAGE)] and to evaluate its performance in detecting multiple sclerosis (MS) brain lesions compared to 2D T2-weighted spin-echo (T2SE). All single-slab 3D sequences and 2DT2SE were acquired in 16 MS patients and 9 age-matched healthy controls. Lesions were scored independently by two raters and characterized anatomically. Two-tailed Bonferroni-corrected Student’s t-tests were used to detect differences in lesion detection between the various sequences per anatomical area after logtransformation. In general, signal and contrast properties of the 3D sequences enabled improved detection of MS brain lesions compared to 2DT2SE. Specifically, 3D-DIR showed the highest detection of intracortical and mixed WM-GM lesions, whereas 3D-FLAIR showed the highest total number of WM lesions. Both 3D-DIR and 3D-FLAIR showed the highest number of infratentorial lesions. 3DT2 and 3D-MPRAGE did not improve lesion detection compared to 2DT2SE. Multi-contrast, isotropic, single-slab 3D MRI allowed an improved detection of both GM and WM lesions compared to 2D-T2SE. A selection of single-slab 3D contrasts, for example, 3D-FLAIR and 3D-DIR, could replace 2D sequences in the radiological practice

Typha latifolia paludiculture effectively improves water quality and reduces greenhouse gas emissions in rewetted peatlands

Paludiculture, the cultivation of crops on wet or rewetted agricultural peatlands, sustainably integrates productive land use with the provision of multiple ecosystem services. Paludiculture crops thrive under waterlogged conditions that stimulate nitrogen (N) and phosphorus (P) removal from soil and water and convert serious drainage-induced carbon (C) losses to C sequestration. Nutrient uptake by paludicrops can prevent mobilisation after rewetting and provide opportunities for purification of nutrient-rich water. Uncertainty remains, however, if and to what extent N loading and a subsequent increase in biomass productivity affect nutrient cycling as well as emissions of the potent greenhouse gases methane (CH4) and nitrous oxide (N2O). In this study, we use mesocosms with rewetted peat to investigate the effect of different N sources in surface water on biomass production of Typha latifolia, a typical paludiculture crop, and the emissions of CH4 and N2O. Organic (Azolla filiculoides; urea) or mineral (KNO3 ; NH4NO) N was supplied either a single time (steady state) or repeatedly (pulse) to simulate a total surface water load of 150 kg N ha(-1) . We found that N stimulated aboveground and belowground biomass production and nutrient uptake by T. latifolia. These effects were absent in Azolla treatments. Whereas after two months CH4 emissions arose to substantial amounts (> 10 mg CH4 m(-2) day(-1)) in unvegetated mesocosms loaded with organic N, they remained very low (<1 mg CH4 m(-2) day(-1)) in vegetated mesocosms, despite the labile C pool in the extensive belowground biomass and organic N loading. Overall, N2O emissions were close to zero and were only detected episodically after NO(3)(- )loading, irrespective of plant presence. Our findings support that T. latifolia as a paludicrop effectively removes various forms of N and P when harvested, and strongly mitigates CH4 emission after the rewetting of agricultural peat soils compared to unvegetated conditions

Regulation of microglial TMEM119 and P2RY12 immunoreactivity in multiple sclerosis white and grey matter lesions is dependent on their inflammatory environment

Multiple Sclerosis (MS) is the most common cause of acquired neurological disability in young adults, pathologically characterized by leukocyte infiltration of the central nervous system, demyelination of the white and grey matter, and subsequent axonal loss. Microglia are proposed to play a role in MS lesion formation, however previous literature has not been able to distinguish infiltrated macrophages from microglia. Therefore, in this study we utilize the microglia-specific, homeostatic markers TMEM119 and P2RY12 to characterize their immunoreactivity in MS grey matter lesions in comparison to white matter lesions. Furthermore, we assessed the immunological status of the white and grey matter lesions, as well as the responsivity of human white and grey matter derived microglia to inflammatory mediators. We are the first to show that white and grey matter lesions in post-mortem human material differ in their immunoreactivity for the homeostatic microglia-specific markers TMEM119 and P2RY12. In particular, whereas immunoreactivity for TMEM119 and P2RY12 is decreased in the center of WMLs, immunoreactivity for both markers is not altered in GMLs. Based on data from post-mortem human microglia cultures, treated with IL-4 or IFNγ+LPS and on counts of CD3+ or CD20+ lymphocytes in lesions, we show that downregulation of TMEM119 and P2RY12 immunoreactivity in MS lesions corresponds with the presence of lymphocytes and lymphocyte-derived cytokines within the parenchyma but not in the meninges. Furthermore, the presence of TMEM119+ and partly P2RY12+ microglia in pre-active lesions as well as in the rim of active white and grey matter lesions, in addition to TMEM119+ and P2RY12+ rod-like microglia in subpial grey matter lesions suggest that blocking the entrance of lymphocytes into the CNS of MS patients may not interfere with all possible effects of TMEM119+ and P2RY12+ microglia in both white and grey matter MS lesions

Axon-Myelin Unit Blistering as Early Event in MS Normal Appearing White Matter

Objective: Multiple sclerosis (MS) is a chronic neuroinflammatory and neurodegenerative disease of unknown etiology. Although the prevalent view regards a CD4 +-lymphocyte autoimmune reaction against myelin at the root of the disease, recent studies propose autoimmunity as a secondary reaction to idiopathic brain damage. To gain knowledge about this possibility we investigated the presence of axonal and myelinic morphological alterations, which could implicate imbalance of axon-myelin units as primary event in MS pathogenesis. Methods: Using high resolution imaging histological brain specimens from patients with MS and non-neurological/non-MS controls, we explored molecular changes underpinning imbalanced interaction between axon and myelin in normal appearing white matter (NAWM), a region characterized by normal myelination and absent inflammatory activity. Results: In MS brains, we detected blister-like swellings formed by myelin detachment from axons, which were substantially less frequently retrieved in non-neurological/non-MS controls. Swellings in MS NAWM presented altered glutamate receptor expression, myelin associated glycoprotein (MAG) distribution, and lipid biochemical composition of myelin sheaths. Changes in tethering protein expression, widening of nodes of Ranvier and altered distribution of sodium channels in nodal regions of otherwise normally myelinated axons were also present in MS NAWM. Finally, we demonstrate a significant increase, compared with controls, in citrullinated proteins in myelin of MS cases, pointing toward biochemical modifications that may amplify the immunogenicity of MS myelin. Interpretation: Collectively, the impaired interaction of myelin and axons potentially leads to myelin disintegration. Conceptually, the ensuing release of (post-translationally modified) myelin antigens may elicit a subsequent immune attack in MS. ANN NEUROL 2021;89:711–725

A more unstable resting-state functional network in cognitively declining multiple sclerosis

Cognitive impairment is common in people with multiple sclerosis and strongly affects their daily functioning. Reports have linked disturbed cognitive functioning in multiple sclerosis to changes in the organization of the functional network. In a healthy brain, communication between brain regions and which network a region belongs to is continuously and dynamically adapted to enable adequate cognitive function. However, this dynamic network adaptation has not been investigated in multiple sclerosis, and longitudinal network data remain particularly rare. Therefore, the aim of this study was to longitudinally identify patterns of dynamic network reconfigurations that are related to the worsening of cognitive decline in multiple sclerosis. Resting-state functional MRI and cognitive scores (expanded Brief Repeatable Battery of Neuropsychological tests) were acquired in 230 patients with multiple sclerosis and 59 matched healthy controls, at baseline (mean disease duration: 15 years) and at 5-year follow-up. A sliding-window approach was used for functional MRI analyses, where brain regions were dynamically assigned to one of seven literature-based subnetworks. Dynamic reconfigurations of subnetworks were characterized using measures of promiscuity (number of subnetworks switched to), flexibility (number of switches), cohesion (mutual switches) and disjointedness (independent switches). Cross-sectional differences between cognitive groups and longitudinal changes were assessed, as well as relations with structural damage and performance on specific cognitive domains. At baseline, 23% of patients were cognitively impaired (≥2/7 domains Z < -2) and 18% were mildly impaired (≥2/7 domains Z < -1.5). Longitudinally, 28% of patients declined over time (0.25 yearly change on ≥2/7 domains based on reliable change index). Cognitively impaired patients displayed more dynamic network reconfigurations across the whole brain compared with cognitively preserved patients and controls, i.e. showing higher promiscuity (P = 0.047), flexibility (P = 0.008) and cohesion (P = 0.008). Over time, cognitively declining patients showed a further increase in cohesion (P = 0.004), which was not seen in stable patients (P = 0.544). More cohesion was related to more severe structural damage (average r = 0.166, P = 0.015) and worse verbal memory (r = -0.156, P = 0.022), information processing speed (r = -0.202, P = 0.003) and working memory (r = -0.163, P = 0.017). Cognitively impaired multiple sclerosis patients exhibited a more unstable network reconfiguration compared to preserved patients, i.e. brain regions switched between subnetworks more often, which was related to structural damage. This shift to more unstable network reconfigurations was also demonstrated longitudinally in patients that showed cognitive decline only. These results indicate the potential relevance of a progressive destabilization of network topology for understanding cognitive decline in multiple sclerosis