Article

Modulating inflammatory monocytes with a unique microRNA gene signature ameliorates murine ALS. J Clin Investig

Department of Neurology, Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
The Journal of clinical investigation (Impact Factor: 13.22). 08/2012; 122(9):3063-87. DOI: 10.1172/JCI62636
Source: PubMed

ABSTRACT

Amyotrophic lateral sclerosis (ALS) is a progressive disease associated with neuronal cell death that is thought to involve aberrant immune responses. Here we investigated the role of innate immunity in a mouse model of ALS. We found that inflammatory monocytes were activated and that their progressive recruitment to the spinal cord, but not brain, correlated with neuronal loss. We also found a decrease in resident microglia in the spinal cord with disease progression. Prior to disease onset, splenic Ly6Chi monocytes expressed a polarized macrophage phenotype (M1 signature), which included increased levels of chemokine receptor CCR2. As disease onset neared, microglia expressed increased CCL2 and other chemotaxis-associated molecules, which led to the recruitment of monocytes to the CNS by spinal cord-derived microglia. Treatment with anti-Ly6C mAb modulated the Ly6Chi monocyte cytokine profile, reduced monocyte recruitment to the spinal cord, diminished neuronal loss, and extended survival. In humans with ALS, the analogous monocytes (CD14+CD16-) exhibited an ALS-specific microRNA inflammatory signature similar to that observed in the ALS mouse model, linking the animal model and the human disease. Thus, the profile of monocytes in ALS patients may serve as a biomarker for disease stage or progression. Our results suggest that recruitment of inflammatory monocytes plays an important role in disease progression and that modulation of these cells is a potential therapeutic approach.

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    • "In addition, miR-146a and miR-149* were down-regulated in our series of ALS patients as compared to controls, and also between bulbar ALS and spinal ALS. Previous studies on miR-146a in ALS patients have shown increased levels as compared to controls, but these investigations were conducted on cerebrospinal fluid [7] or spinal cord tissue [21] , possibly explaining this apparently discordant finding. Another novel and interesting result from our study is the demonstration that myostatin/follistatin levels were increased in ALS patients as compared to controls, and that this increase is especially observed in bulbar ALS. "
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    ABSTRACT: Aims: The identification of circulating biomarkers is needed to facilitate diagnosis and prognosis of amyotrophic lateral sclerosis (ALS) and to offer indicators of therapeutic response in clinical trials. We aimed to investigate the levels of muscle-specific microRNAs in serum of ALS patients subdivided according to bulbar or spinal onset. Methods: In 14 ALS patients (10 spinal, 4 bulbar) we measured the serum levels of muscle-specific miR-206, miR-1, miR-133a/b, miR-27a, and the expression of myostatin and follistatin, which are negative regulators of muscle growth. Morphometric analysis of muscle fiber size was used to correlate muscle atrophy with biochemical-molecular parameters. Results: In ALS patients the expression of miR-206 and miR-133 was significantly increased and that of miR-27a was significantly reduced as compared to controls, and also between spinal vs. bulbar ALS. Myostatin/follistatin ratio was significantly higher in ALS than in controls and in bulbar versus spinal ALS. Bulbar ALS patients present higher degree of muscle atrophy than spinal ALS, as documented by our muscle fiber morphometric analysis. Conclusions: Muscle mass regulators are particularly down-expressed in bulbar ALS, suggesting a more rapid and diffuse atrophic process. These biomarkers may be considered as useful biochemical and molecular indicators involved both in neuromuscular junction maintenance and reinnervation process.
    Full-text · Article · Nov 2015 · Clinical neuropathology
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    • "Consistently, a more recent work identified CD39, the dominant cellular ectonucleotidase that degrades ATP and ADP to AMP, to be down-regulated at the mRNA level in microglia derived from the spinal cord of SOD1-G93A mice and, furthermore, in lumbar ventral horns of spinal cord from ALS subjects (Table 2) (Butovsky et al., 2015). As microglia are the only cells in the CNS that express CD39 (Braun et al., 2000; Butovsky et al., 2012), this last finding further underlines the importance of this enzyme in sustaining purinergic inflammatory pathways in ALS microglia. The modulation of CD39 expression has now been documented also at the protein level in ALS cortical primary microglia (Box 1). "
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    ABSTRACT: By signalling through ionotropic P2X (for ATP) and metabotropic P1 (for adenosine) and P2Y (mainly ADP, UDP, UTP, ATP) purinergic receptors, the extracellular nucleotides ATP, UTP and their metabolic derivatives originated by extracellular activity of several different ectonucleotidases, are involved in the functioning of the nervous system where they exert a central role during physiological processes, but also in the precarious balance between beneficial and noxious events. Indeed, in recent years, the dysregulation of extracellular purinergic homeostasis has been correlated to well-characterized acute and chronic neurodegenerative and neuroinflammatory diseases. Among these, we focus our attention on purinergic signalling occurring in amyotrophic lateral sclerosis (ALS), the most common late onset motoneuron disease, characterized by specific loss of motoneurons in brain stem and ventral horns of spinal cord. ALS is a progressive non-cell-autonomous and multifactorial neuroinflammatory disease, whose aetiology and pathological mechanisms are unidentified for most patients and initiate long before any sign or symptom becomes apparent. By combining purinergic with ALS knowledge, in this work we thus present and sustain a novel line of investigation on the purinergic contribution to ALS. In particular, here we recapitulate very early results about P2X4, P2X7 and P2Y6 receptor expression in tissues from ALS animal and cell models and patients, and more recent achievements about purinergic signalling mainly performed in vitro in microglia and lately in astrocytes and motoneurons. We finally highlight how purinergic signalling has progressively evolved up to preclinical trials, to the point of deserving now full consideration with reference to ALS.
    Full-text · Article · Oct 2015 · Neuropharmacology
    • "Thereby, miRNA expression profiles can reflect activation of specific pathogenic pathways. Dysregulation of miRNA expression has been reported, for example, in the SOD1-G93A mouse model of ALS or patient-derived tissue (Butovsky et al., 2012; Campos-Melo et al., 2013; De Felice et al., 2012; Toivonen et al., 2014). miRNAs are remarkably stable in serum and other body fluids as exosomal cargos or bound to specific proteins (Xu et al., 2012), and disease-related changes of extracellular miRNA abundance has been repeatedly shown. "
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    ABSTRACT: MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression and specific mircoRNA "fingerprints" are thought to contribute to and/or reflect certain disease conditions. Recently, we identified surprisingly homogeneous signatures of circulating miRNAs in the serum of familial amyotrophic lateral sclerosis (ALS) patients, which were already present in presymptomatic carriers of ALS gene mutations. Here, we characterize circulating miRNAs in the serum of sporadic ALS patients. We show that, in contrast to familial ALS, miRNA signatures of sporadic ALS are highly heterogeneous suggesting a number of different etiologies. Nevertheless, 2 miRNAs, miR-1234-3p and miR-1825, could be identified to be consistently downregulated in sporadic ALS. Bioinformatic analysis revealed miRNA fingerprints resembling those of familial ALS patients and mutation carriers in 61% of sporadic ALS patients, while the remaining subgroup had clearly different miRNA signatures. These data support a higher than expected contribution of genetic factors also to sporadic ALS. Moreover, our results indicate a more heterogeneous molecular etiology of sporadic ALS compared with (mono)genic cases, which should be considered for the development of disease modifying treatments. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Jun 2015 · Neurobiology of Aging
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