Promoting remyelination is recognized as a novel strategy to foster repair in neurodegenerative demyelinating diseases, such as multiple sclerosis. In this respect, the receptor GPR17, recently emerged as a new target for remyelination, is expressed by early oligodendrocyte precursors (OPCs) and after a certain differentiation stage it has to be downregulated to allow progression to mature myelinating oligodendrocytes. Here, we took advantage of the first inducible GPR17 reporter mouse line (GPR17‐iCreERT2xCAG‐eGFP mice) allowing to follow the final fate of GPR17+ cells by tamoxifen‐induced GFP‐labeling to unveil the destiny of these cells in two demyelination models: experimental autoimmune encephalomyelitis (EAE), characterized by marked immune cell activation and inflammation, and cuprizone induced demyelination, where myelin dysfunction is achieved by a toxic insult. In both models, demyelination induced a strong increase of fluorescent GFP+ cells at damaged areas. However, only in the cuprizone model reacting GFP+ cells terminally differentiated to mature oligodendrocytes, thus contributing to remyelination. In EAE, GFP+ cells were blocked at immature stages and never became myelinating oligodendrocytes. We suggest these strikingly distinct fates be due to different permissiveness of the local CNS environment. Based on previously reported GPR17 activation by emergency signals (e.g., Stromal Derived Factor‐1), we propose that a marked inflammatory milieu, such as that reproduced in EAE, induces GPR17 overactivation resulting in impaired downregulation, untimely and prolonged permanence in OPCs, leading, in turn, to differentiation blockade. Combined treatments with remyelinating agents and anti‐inflammatory drugs may represent new potential adequate strategies to halt neurodegeneration and foster recovery.
In the mature central nervous system (CNS), oligodendrocytes provide support and insulation to axons thanks to the production of a myelin sheath. During their maturation to myelinating cells, oligodendroglial precursors (OPCs) follow a very precise differentiation program, which is finely orchestrated by transcription factors, epigenetic factors and microRNAs (miRNAs), a class of small non-coding RNAs involved in post-transcriptional regulation. Any alterations in this program can potentially contribute to dysregulated myelination, impaired remyelination and neurodegenerative conditions, as it happens in multiple sclerosis (MS). Here, we identify miR-125a-3p, a developmentally regulated miRNA, as a new actor of oligodendroglial maturation, that, in the mammalian CNS regulates the expression of myelin genes by simultaneously acting on several of its already validated targets. In cultured OPCs, over-expression of miR-125a-3p by mimic treatment impairs while its inhibition with an antago-miR stimulates oligodendroglial maturation. Moreover, we show that miR-125a-3p levels are abnormally high in the cerebrospinal fluid of MS patients bearing active demyelinating lesions, suggesting that its pathological upregulation may contribute to MS development, at least in part by blockade of OPC differentiation leading to impaired repair of demyelinated lesions.
Detection of early carotid vascular disease in patients with systemic lupus erythematosus (SLE) is considered mandatory for evaluation of subclinical atherosclerosis (ATS), and various ultrasonographic (US) parameters have been proposed. In the present investigation, 33 SLE and 33 healthy age-matched females have been studied by colour-coded sonography of the common carotid artery, assessing intima-media thickness (IMT), vascular strain (VS), vascular distensibility (VD), vascular stiffness (VSf) and pressure-strain elastic modulus (PSEM) as possible markers of early ATS. Patients with SLE, despite equivalent exposure to "traditional" cardiovascular risk factors, presented a higher mean IMT of the common carotid artery than healthy subjects (0.7 +/- 0.2 mm vs 0.5 +/- 0.1 mm - P < 0.0001). Of the stiffness parameters, patients with lupus showed a mean VSf of 0.72 +/- 0.38 vs 0.54 +/- 0.14 in controls (P < 0.0001) and a mean PSEM of 6.0 +/- 2.8 Pa vs 3.0 +/- 1.4 Pa in controls (P < 0.0001). Mean VS and VD were significantly lower in patients with SLE than in healthy subjects (P < 0.0001). Among individuals with IMT < 0.6 mm, patients with SLE presented more compromised stiffness parameters. IMT was shown to be a useful parameter in the evaluation of vascular damage, even in a "sub-clinical" phase, while stiffness parameters provide additional details regarding endothelial and vessel functional state. Combined evaluation may allow ATS to be detected in the early stages in patients with SLE.
Alexithymia is conceptualized as a disorder of emotion regulation mechanisms, which involves a dissociation of emotional and physical responses to life events and bodily sensations. Our results might suggest a possible relationship between the alexithymic construct and TNF levels in RA patients. These preliminary findings corroborate the integrated bidirectional interactions between neuropsychological mechanisms and the neuroendocrine-immune system in patients affected by autoimmune diseases and contribute to finding a common biological pathway linking alexithymia and autoimmune-inflammatory diseases.
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