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StartNeuroscienceFrontiers | MicroRNA Alterations in Persistent Traumatic Encephalopathy and Amyotrophic Lateral Sclerosis

Frontiers | MicroRNA Alterations in Persistent Traumatic Encephalopathy and Amyotrophic Lateral Sclerosis


Persistent traumatic encephalopathy (CTE) is a neurodegenerative illness related to years publicity to repetitive head impacts (RHI). Persistent traumatic encephalopathy has been reported in all kinds of RHI exposures, together with contact sports activities equivalent to American soccer, boxing, hockey, and rugby in addition to from navy blast accidents. Medical signs might contain a number of domains, together with temper, conduct, and cognitive features (Katz et al., 2021). In some circumstances, motor signs can emerge within the type of parkinsonism (Adams et al., 2018) or motor neuron illness/amyotrophic lateral sclerosis (ALS) (McKee et al., 2009). Amyotrophic lateral sclerosis is 4 occasions extra frequent in Nationwide Soccer League gamers (Lehman et al., 2012; Daneshvar et al., 2021) and is discovered inside ∼6% of contact sports activities athletes with CTE (Mez et al., 2017). Microscopically, the hallmark of CTE includes phosphorylated tau (p-tau) neurofibrillary tangles (NFTs) that accumulate inside neurons and neuronal processes within the cerebral cortex, preferentially at sulcal depths and round blood vessels. TDP-43 is current in roughly half of low stage (stage I and II) CTE and first seems throughout the CTE p-tau lesions on the sulcal depths of the frontal cortex (Danielsen et al., 2017). In excessive stage (stage III and IV) CTE, TDP-43 pathology is extra frequent and includes further mind areas (McKee et al., 2013).

Amyotrophic lateral sclerosis (ALS) is characterised by progressive degeneration of motor neurons throughout the motor cortex of the mind (higher motor neurons) and spinal wire (decrease motor neurons). Signs sometimes manifest in a single area of the physique and progress to paralysis, respiratory failure, and eventual loss of life. In most sporadic circumstances, pTDP-43 inclusions are current inside motor neurons and variably in different areas of the mind. The illness course tends to be speedy with loss of life occurring in 2 to five years. Each genetic and environmental elements are linked to the etiology of ALS (Saez-Atienzar et al., 2021). A 2007 examine discovered {that a} analysis of ALS was 11-fold larger in these with a number of head accidents inside 10 years than in these with no head accidents (H. Chen et al., 2007; Schmidt et al., 2010).

Persistent traumatic encephalopathy (CTE) with TDP-43 proteinopathy and ALS was first reported involved sport athletes, together with 2 former NFL athletes and one skilled boxer (McKee et al., 2010) in addition to a younger soccer participant (McKee et al., 2014). In a examine accomplished on the navy cohort of the Division of Veterans Affairs Biorepository Mind Financial institution 5.8% of these with ALS have been additionally comorbid with CTE. These comorbid topics have been extra prone to have a historical past of traumatic mind harm (TBI). Clinically, they have been extra prone to have a bulbar onset and temper and behavioral alterations (Moszczynski et al., 2018; Walt et al., 2018).

MicroRNAs (miRNAs) are small non-coding strands of RNA of roughly 22 base pairs which might be concerned in regulating translation of messenger RNA. They aim mRNA on the 3′ UTR and will both silence their translation or degrade them (O’Brien et al., 2018). MiRNAs are pretty new within the biomarker subject and several other research have been carried out that describe that their fluctuations in relation to ailments equivalent to ALS and Alzheimer’s illness (Cheng et al., 2015; Mez et al., 2017; Miya Shaik et al., 2018; Ricci et al., 2018; Dewan and Traynor, 2021; Magen et al., 2021). Their putative involvement in CTE is to date unknown.

The overlap in CTE and ALS pathologies and danger elements suggests they could share widespread illness mechanisms, but the pathways of neurodegeneration is perhaps sufficiently divergent to permit biomarker distinctions and analysis throughout life. Right here we got down to decide whether or not miRNA ranges have been altered within the prefrontal cortex of individuals with CTE, ALS, and comorbid CTE + ALS in comparison with controls. We hypothesized that particular person miRNAs could be differentially regulated in every illness and that some miRNAs could be shared by CTE and ALS.

Supplies and Strategies

Members and Pathological Teams

Mind donors have been chosen from the Division of Veterans Affairs Biorepository Mind Financial institution (Brady et al., 2013) and the Understanding Neurology Harm and Traumatic Encephalopathy (UNITE) examine mind financial institution (Mez et al., 2015, 2017). All consents for analysis participation and mind donation have been offered by subsequent of kin. Institutional Evaluate Boards of the Boston and Bedford VA Healthcare Programs and Boston College Medical Heart accredited the related examine protocols.

All brains have been examined by neuropathologists (TS, AM, BH, VA) with no data of the scientific information. Diagnoses have been made utilizing beforehand reported protocols and well-established standards (Mez et al., 2015). The analysis of ALS required degeneration of higher and decrease motor neurons with degeneration of lateral and ventral corticospinal tracts of the spinal wire and lack of anterior horn cells from cervical, thoracic and lumbar spinal wire with gliosis (Mackenzie et al., 2010). Persistent traumatic encephalopathy was recognized utilizing established Nationwide Institute of Neurological Problems and Stroke, NIBIB consensus standards (McKee et al., 2016; Bieniek et al., 2021) and the McKee staging system (McKee et al., 2013; Alosco et al., 2020).

Mind donors have been age and intercourse (all males) matched, had no different neurodegenerative illness co-morbidities and CTE circumstances have been chosen to incorporate all 4 phases. The teams included 16 individuals with CTE, 12 with CTE and ALS (CTE + ALS), and a couple of controls from the UNITE mind financial institution (Mez et al., 2015). Fourteen individuals with ALS, 9 with CTE + ALS, and 5 controls have been chosen based mostly on matching analysis, age, and intercourse from the Division of VABBB (Brady et al., 2013). A further 13 controls have been included from the VA Nationwide Publish-Traumatic Stress Dysfunction mind financial institution (Friedman et al., 2017). Controls have been with no scientific neurodegenerative illness at submit mortem examination. General, there have been 71 individuals, 16 within the CTE group, 21 within the CTE + ALS group, 14 within the ALS group, and 20 individuals within the management group (Desk 1). There was no vital distinction within the age at loss of life or RIN values between the teams.

Desk 1. Variation in pathological group demographics.

MiRNA Choice

A customized miRNA plate (Utilized BioSystems, Waltham MA) was designed to incorporate 47 targets beforehand implicated in human neurodegenerative ailments together with Alzheimer illness, ALS, A number of Sclerosis and Huntington’s illness as decided by PubMed search in Might 2019 (Supplementary Tables 1, 2). This examine is the primary to look at miRNA ranges in CTE. MiRNA pathways have been decided by way of Pubmed searches carried out in December 2019 utilizing phrases together with every miRNA identify, Alzheimer Illness, ALS, Huntington’s illness, TBI, a number of sclerosis, Parkinson’s illness, inflammatory, cell loss of life, apoptosis, cell progress, cell proliferation, improvement, human mind. Every particular person miRNA could also be concerned in a number of completely different processes, and there may be probably overlap between concerned pathways.

Samples and MiRNA Extraction

Complete mind and spinal wire have been half frozen and half mounted for full neuropathological workup as described beforehand (Brady et al., 2013; Mez et al., 2015). miRNAs have been measured inside frozen dorsolateral prefrontal cortex grey matter. This area was chosen as a result of it’s affected in each ailments and has been utilized in earlier research of gene expression in neurodegenerative ailments (Labadorf et al., 2018).

Roughly 30 mg of frozen prefrontal cortex was homogenized over moist ice by hand utilizing thioglyecrol offered by the Maxwell RSC miRNA package (Promega, Madison WI). From this similar package the homogenized tissue was then processed with lysis buffer, DNase and proteinase Okay options. The answer was then inserted right into a ready-made cartridge from the package with all of the reagents wanted for extraction. MiRNA was extracted and eluted utilizing the Maxwell 16 Instrument (Promega).

Quantitative Actual Time Polymerase Chain Response

Samples have been diluted to 5ng/μl and transcribed into cDNA utilizing a Taqman Superior MiRNA cDNA Synthesis Equipment from Utilized BioSciences. The cDNA underwent a further amplification step to extend yields of unstable miRNAs (MiR-Amp). Samples have been diluted 1:10 and loaded onto qPCR plates with Taqman Quick Superior Grasp Combine. Every pattern obtained 2 qPCR runs utilizing the StepOnePlus Actual Time polymerase chain response (PCR) System (Utilized Biosystems, Foster Metropolis, CA), together with one to guage for U6 a small non-coding spliceosome RNA that may be a widespread endogenous management (Campos-Melo et al., 2013). The following qPCR run was with the customized miRNA plates with primers for chosen targets. Samples have been examined in duplicate.

Statistical Evaluation

Targets that have been efficiently amplified had their ΔCT calculated utilizing U6 endogenous management values. All statistics and graphs have been generated utilizing GraphPad Prism. Outliers have been excluded utilizing the ROUT technique set to 0.1%, which resulted within the exclusion of miR-15a-5p from one CTE + ALS pattern. Important adjustments in every miRNA ΔCT have been decided between experimental teams and controls utilizing ANOVA with Dunnett’s a number of comparability testing. In an effort to additional account for the a number of miRNAs examined, a Bonferroni correction of α-value (0.05) divided by the variety of efficiently amplified miRNA (38) was utilized to offer a cut-off p-value of 0.00132. For the needs of graphing the relative change was calculated utilizing the two–ΔΔCT technique (Livak and Schmittgen, 2001).


A complete of 38 of the 47 targets have been efficiently amplified, indicating dependable expression within the human prefrontal cortex. Of these 38 miRNAs, 28 confirmed a major distinction in ΔCT values throughout pathology teams utilizing ANOVA (Desk 2). Determine 1 reveals the distribution and overlap of upregulated miRNA throughout pathology teams.

Desk 2. Modifications in miRNA expression between pathological teams.

Determine 1. Venn Diagram exhibiting distinct and overlapping considerably altered miRNA inside CTE, ALS, and CTE + ALS in comparison with controls. Daring and underline signifies a p-value at or under the Bonferroni variety of 0.0013. Purple signifies miRNAs concerned in inflammatory pathways; inexperienced signifies cell progress; blue signifies apoptotic; and black signifies miRNA that didn’t slot in any group.

MiRNAs considerably upregulated throughout pathology teams are summarized in Desk 3. These altered in just one illness group included two (7%) miRNAs (miR-34a-5p and miR-10b-5p) upregulated in ALS; 5 miRNAs (18%; miR-124-3p, miR-181c-5p, miR-197-3p, miR-16-5p, and miR-100-5p) have been considerably altered in CTE; and two (7%; miR-30c-5p and miR-210-3p) have been distinctive to CTE + ALS. Of the miRNAs that have been considerably altered in two illness teams, two miRNAs (7%; miR-146b-5p and miR-148a-3p) have been upregulated in ALS and CTE; two (7%; miR-196a-5p and miR-30e-5p) have been upregulated in each ALS and within the CTE + ALS; eleven (39%; miR-125b-5p, miR-9-5p, let-7i-5p, miR-26a-5p, miR-26b-5p, miR-30d-5p, miR-128-3p, miR-34c-5p, miR-19b-3p, miR-186 and let-7b-5p) have been upregulated in CTE and CTE + ALS. Lastly, 4 miRNAs (14%; miR-146a-5p, miR-107, miR-15a-5p and miR-221-3p) had vital upregulation in all 3 pathological teams (Determine 1). Solely miR-10b had a p-value lower than 0.00132 (Bonferroni corrected for a number of comparisons).

Desk 3. Upregulated miRNAs between management and pathology teams.

Primarily based on earlier research, miRNAs have been categorized in accordance with their position in physiological processes. Nearly all of miRNAs altered in ALS, CTE, or CTE + ALS have roles in irritation, apoptosis, or cell progress and differentiation (Supplementary Tables 35). Particularly, eight (29%) upregulated miRNAs are concerned in inflammatory processes (Determine 2), 9 (32%) are concerned in cell progress and differentiation (Determine 3) and 10 (36%) play a job in apoptosis (Determine 4). There was one miRNA (3%) (miR-186) that was upregulated in CTE and CTE + ALS that has been proven to have an effect on synaptic exercise and inhibit BACE1 (Kim et al., 2016). The cell progress and differentiation miR-10b was elevated in ALS, however not CTE or CTE + ALS (Determine 3). Apoptotic miRNAs have been elevated equally throughout ALS, CTE, and CTE + ALS (Determine 4).

Determine 2. Cell Development and Differentiation miRNAs considerably altered in CTE, ALS, or CTE + ALS. MiR-10b was upregulated in ALS alone. MiR-146b-5p and miR-148a-3p have been considerably upregulated in non-comorbid ALS and CTE. MiR-197-3p was upregulated in CTE. 4 miRNAs, miR-26a-5p, miR-26b-5p, miR-128-3p, miR-34c-5p have been upregulated in CTE and CTE + ALS. Lastly, miR-15a-5p was upregulated in all 3 circumstances. Error bars denote commonplace error of the imply. *p < 0.05, **p < 0.01 in comparison with management group. Consult with Desk 3 for statistical analyses between the pathologic teams and the management group.

Determine 3. Inflammatory miRNAs considerably altered in CTE, ALS, or CTE + ALS. MiR-124-3p, miR-181c-5p have been considerably upregulated in CTE solely. MiR-9-5p, let-7b-5p, miR-125-5p, let-7b-5p have been considerably upregulated in each CTE and CTE + ALS. MiR-210-3p was considerably upregulated in comorbid CTE + ALS. Lastly, miR-146a-5p and miR-107 have been considerably upregulated in all three teams. Error bars denote commonplace error of the imply. *p < 0.05, **p < 0.01 in comparison with management group. Consult with Desk 3 for statistical analyses between the pathologic teams and the management group.

Determine 4. Apoptotic miRNAs considerably altered in CTE, ALS, or CTE + ALS. MiR-34a-5p-5p was considerably upregulated in ALS alone. miR-16-5p and miR-100-5p have been upregulated in CTE. MiR-30c-5p was upregulated in comorbid CTE + ALS. MiR-196a-5p and miR-30e-5p miRNAs have been upregulated in each ALS and CTE + ALS. Let-7i-5p, miR-30d-5p, and miR-19-3p have been upregulated in each CTE and CTE + ALS. Lastly, miR-221-3p was upregulated in all three teams. Error bars denote commonplace error of the imply. *p < 0.05, **p < 0.01 in comparison with management group. Consult with Desk 3 for statistical analyses between the pathologic teams and the management group.

Inside every illness, the proportion of miRNA pathways concerned differed (Determine 5). In ALS, altered miRNAs have been most incessantly concerned in cell progress (40%) and apoptosis (40%) and fewer incessantly irritation (20%). CTE additionally confirmed frequent alterations in cell progress (36%), however higher involvement in inflammatory pathways (32%) in comparison with ALS. Lastly, when ALS and CTE have been comorbid, apoptosis (37%) and inflammatory (32%) pathways have been probably the most incessantly concerned.

Determine 5. Frequency of miRNA pathways in illness. MiRNAs have been labeled into inflammatory, cell progress, apoptotic, and different pathways and the frequency inside every pathway is proven. (A). Frequency of miRNA pathways in ALS. (B). Frequency of miRNA pathways in CTE. (C). Frequency of miRNA pathways in CTE + ALS.


General, we discovered that CTE and ALS have been characterised by related adjustments in miRNAs beforehand implicated in neurological illness. Nearly all of miRNAs (72%) have been equally concerned in ALS and CTE, suggesting widespread pathogenetic pathways of irritation, cell progress, and apoptosis. Essentially the most considerably modified miRNA was miR-10b-5p, which was elevated in ALS.

Cell Development and Differentiation Pathways

MiR-10b is concerned in cell progress and differentiation pathways. Mir-10b-5p has been proven to work together with the HOX gene cluster in each Alzheimer’s illness (AD) (Ruan et al., 2021) and Huntington’s illness (Hoss et al., 2014). In Alzheimer illness Ruan and colleagues confirmed that HOX genes have been decreased and inhibited by miR-10b-5p, resulting in extra extreme illness. Hoss et al. confirmed that three miRNAs that originate at or close to the HOX gene cluster, miR-10b-5p, miR-196a-5p and miR-148a-3p, are considerably upregulated in Huntington’s illness, a neurodegeneration characterised by motor dysfunction, persona change, and cognitive decline. MiR-10b-5p has been studied in its relation to ALS although outcomes have been blended. Down regulation in ALS has been noticed in muscle tissue (Si et al., 2018) and in plasma (Banack et al., 2020), however upregulation has been noticed in entire blood (De Felice et al., 2018).

One other goal of miR-10b-5p is mind derived neurotrophic progress issue (BDNF), which is a key regulator of cell progress and plasticity within the mind and has been proven to reinforce cell survival. MiR-10b-5p has been proven to immediately inhibit BDNF (L. Wang et al., 2020). The BDNF/TrkB pathway has been proven to be altered in ALS and BDNF was elevated in skeletal muscle (Lanuza et al., 2019). Decreases in BDNF have additionally been reported after TBI (Korley et al., 2016), in AD, and in growing older (Jiao et al., 2016). Different miRNAs that disrupt BDNF and could also be concerned embrace miR-26a-5p, miR-26b-5p, and miR-15a-5p. These have been additionally discovered to be altered in CTE and CTE + ALS.

Inflammatory Pathways

Altered inflammatory pathways are a function of RHI and CTE (Cherry et al., 2016, 2021) and ALS (Spencer et al., 2020), and quite a few miRNAs would possibly regulate these processes (Supplementary Desk 3). Of the miRNAs altered in CTE and CTE + ALS in comparison with ALS, many have been inflammatory, which helps the roles of RHI and irritation in CTE pathogenesis. Then again, some inflammatory miRNAs have been upregulated equally in all three illness teams (miR-146a-5p, miR-107). MiR-146a-5p and miR-107 together with miR-9-5p, miR-181c-5p and miR-125b-5p are concerned within the NF-κB pathway. The NF-κB has been beforehand implicated in ALS (Parisi et al., 2016; Tahamtan et al., 2018; Slota and Sales space, 2019; Källstig et al., 2021) and TBI (Jassam et al., 2017; Pierre et al., 2021). Exterior of the NF-κB pathway, miR-125b-5p has been immediately implicated in hyperphosphorylation of tau (Banzhaf-Strathmann et al., 2014) and would possibly contribute to CTE pathogenesis.

Apoptotic Pathways

A number of upregulated miRNAs have a job in apoptosis and autophagy in neurodegenerative ailments. Protein and broken cell clearance are particularly essential in ALS and CTE through which irregular p-TDP-43 and p-tau proteins accumulate. MiRNAs associated to apoptosis and autophagy have been the predominantly altered group in ALS and CTE + ALS (Determine 5). MiR-34a-5p upregulation was distinctive to ALS. It has been beforehand demonstrated an upregulation within the plasma of familial ALS analysis individuals with the C9orf72 mutation (Kmetzsch et al., 2021). The autophagy pathway is primarily regulated by inhibition of mTOR (mammalian goal of rapamycin). mTOR is immediately inhibited by miR-100-5p which was additionally discovered to be upregulated in CTE and has beforehand been implicated in altered protein deposition in AD (Ye et al., 2015). PI3K/akt, an activator of mTOR which is inhibited by miR-16-5p (T. Li et al., 2019), additionally discovered to be upregulated in CTE. One other key participant in each apoptosis and autophagy pathways is Beclin, which fosters elimination of previous proteins and broken cells. MiR-30c-5p, miR-30d-5p, and miR-30e-5p have been all upregulated in ALS and CTE and have been proven to inhibit Beclin (Millan, 2017; Zhao et al., 2017), a protein concerned in apoptosis and autophagy.

Biomarker Improvement

MiRNAs have been proposed as potential biomarkers for illness (Ghosh et al., 2021). At present, CTE can solely be recognized at post-mortem and ALS is often recognized after motor features have declined. It stays to be decided whether or not miRNAs, equivalent to miR-10b-5p are altered in biofluids such because the cerebrospinal fluid or blood throughout life in people with ALS or CTE. There have been latest research which have examined the utility of choose miRNA biomarkers in blood. MiR-181 is broadly expressed in neurons and could also be a marker for neuronal density, and miR-181 ranges in serum have not too long ago been related to elevated danger of loss of life in ALS (Magen et al., 2021). We didn’t see variations in ALS prefrontal cortex however discovered that miR-181c-5p was considerably upregulated within the CTE group. Different promising miRNA targets which may be used as blood biomarkers of ALS sufferers embrace miR-206 and miR-124-3p (Soliman et al., 2021; Vaz et al., 2021). Correlations with blood and mind miRNA ranges require additional examine.


There have been a number of limitations to this examine. Solely choose miRNAs beforehand implicated in neurological illness have been examined. Future research ought to embrace extra circumstances and look at further miRNA targets in addition to correlation between miRNA expression and markers for irritation, cell progress, and apoptosis. This examine additionally targeted on adjustments in miRNAs inside postmortem tissue from prefrontal cortex. Whether or not these adjustments are particular to prefrontal cortex in CTE and ALS or traits of widespread mind areas stays to be decided. Postmortem human mind tissue was evaluated; nonetheless, miRNAs are usually steady to degradation, and RIN values, a measure of tissue high quality, weren’t considerably completely different between teams. Examine individuals have been restricted to primarily Caucasian males, limiting the generalizability of those findings.


Shared miRNA alterations in CTE and ALS recommend that irritation, apoptosis, and cell progress are neurodegenerative pathways widespread to each problems. Distinctive will increase in miR-100-5p in mind donors with CTE, and distinctive will increase in miR-10b-5p in mind donors with ALS recommend that miRNA evaluation would possibly show helpful in distinguishing these problems however would require future research of further mind donors utilizing broader areas of mind and spinal wire. Future research in biofluids throughout life are warranted, together with cerebrospinal fluid and serum, to find out the utility of miRNAs for potential biomarker improvement. General, these shared and distinct miRNA profiles recommend that miRNA evaluation would possibly show helpful sooner or later improvement of biomarkers for CTE and ALS.

Information Availability Assertion

The unique contributions offered within the examine are included within the article/Supplementary Materials, additional inquiries could be directed to the corresponding creator.

Creator Contributions

MaA and TS: examine design, conception, and drafting of the manuscript. MaA, TS, NA, KS, ZF, NR, LG, IR, JA, SW, VA, BH, RM, KC, RN, MP, AL, FA, JM, NK, AM, and CB: acquisition and evaluation of knowledge. All authors contributed to the article and accredited the submitted model.


This work was supported by the US (U.S.) Division of Veterans Affairs, Veterans Well being Administration, Veterans Affairs Biorepository (BX002466), Medical Sciences Analysis and Improvement Advantage Award (I01-CX001038), BLRD Advantage Award (I01-BX005161), Nationwide Institute of Neurological Problems and Stroke (U54NS115266, U01NS086659, and K23NS102399), Nationwide Institute of Growing older Boston College AD Analysis Heart (P30AG072978) and the Concussion Legacy Basis. This work was additionally supported by unrestricted presents from the Andlinger Basis and WWE.

Battle of Curiosity

The authors declare that the analysis was carried out within the absence of any business or monetary relationships that might be construed as a possible battle of curiosity.

Writer’s Be aware

All claims expressed on this article are solely these of the authors and don’t essentially symbolize these of their affiliated organizations, or these of the writer, the editors and the reviewers. Any product which may be evaluated on this article, or declare which may be made by its producer, isn’t assured or endorsed by the writer.


We wholeheartedly acknowledge the usage of sources and services on the Edith Nourse Rogers Memorial Veterans Hospital (Bedford, MA), Jamacia Plain VA Medical Heart in addition to the donors and their households who make this analysis doable.

Supplementary Materials

The Supplementary Materials for this text could be discovered on-line at:



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