Ethanol inhibits skeletal muscle cell proliferation and delays its differentiation in cell culture

Exposomic Signatures of Cervical Pain

INTRODUCTION

We evaluated risk factors associated with cervical pain (CP) among officers and enlisted members of the U.S. Army and Marine Aviation community using an exposomic approach. Specifically, we aimed to determine the factors associated with reported CP.

MATERIALS AND METHODS

This is a retrospective cohort study that utilized the Medical Assessment and Readiness System housed at Womack Army Medical Center to evaluate the longitudinal data taken from medical and workforce resources. This study included 77,864 active duty AMAC members during October 2015-December 2019. Multivariable mixed-effects logistic regression was used to assess the relationship between the independent variables of rank, service time, deployment, Armed Forces Qualification Test score, tobacco use, alcohol use, age, gender, race, ethnicity, body mass index, marital status, and education level and the dependent variable, incidence occurrence of CP.

RESULTS

The total analysis included 77,864 individuals with 218,180 person-years of observations. The incidence rate of CP was 18.8 per 100 person-years, with a 12% period prevalence. Cervical pain was independently associated with rank, service time, Armed Forces Qualification Test score, and alcohol use (all P < .05).

CONCLUSIONS

Our longitudinal exposomic signatures-based approach aims to complement the outcomes of data science and analytics from Medical Assessment and Readiness System with validations of objective biochemical indicator species observed in Army and Marine Aviation community members suffering from CP. This initial approach using parallel track complementarity has the potential of substantiating the underlying mechanisms foundational to design prospective personalized algorithms that can be used as a predictive model. Finally, a specific evaluation of occupational risk factors may provide insight into factors not readily ascertained from the civilian literature.

The functional and molecular effects of problematic alcohol consumption on skeletal muscle: a focus on athletic performance

Background: Chronic alcohol misuse is associated with alcoholic myopathy, characterized by skeletal muscle weakness and atrophy. Moreover, there is evidence that sports-related people seem to exhibit a greater prevalence of problematic alcohol consumption, especially binge drinking (BD), which might not cause alcoholic myopathy but can negatively impact muscle function and amateur and professional athletic performance.Objective: To review the literature concerning the effects of alcohol consumption on skeletal muscle function and structure that can affect muscle performance.Methodology: We examined the currently available literature (PubMed, Google Scholars) to develop a narrative review summarizing the knowledge about the effects of alcohol on skeletal muscle function and exercise performance, obtained from studies in human beings and animal models for problematic alcohol consumption.Results: Exercise- and sport-based studies indicate that alcohol consumption can negatively affect muscle recovery after vigorous exercise, especially in men, while women seem less affected. Clinical studies and pre-clinical laboratory research have led to the knowledge of some of the mechanisms involved in alcohol-related muscle dysfunction, including an imbalance between anabolic and catabolic pathways, reduced regeneration, increased inflammation and fibrosis, and deficiencies in energetic balance and mitochondrial function. These pathological features can appear not only under chronic alcohol misuse but also in other alcohol consumption patterns.Conclusions: Most laboratory-based studies use chronic or acute alcohol exposure, while episodic BD, the most common drinking pattern in amateur and professional athletes, is underrepresented. Nevertheless, alcohol consumption negatively affects skeletal muscle health through different mechanisms, which collectively might contribute to reduced sports performance.

Evaluation of chemotherapeutic and cancer-protective properties of sphingosine and C2-ceramide in a human breast stem cell derived carcinogenesis model

The overall goal of the present study was to evaluate the chemotherapeutic and cancer-protective properties of D-erythro-sphingosine (sphingosine) and C₂-ceramide using a human breast epithelial cell (HBEC) culture system, which represents multiple-stages of breast carcinogenesis. The HBEC model includes Type I HBECs (normal stem), Type II HBECs (normal differentiated) and transformed cells (immortal/non-tumorigenic cells and tumorigenic cells, which are transformed from the same parental normal stem cells). The results of the present study indicate that sphingosine preferentially inhibits proliferation and causes death of normal stem cells (Type I), tumorigenic cells, and MCF7 breast cancer cells, but not normal differentiated cells (Type II). In contrast to the selective anti-proliferative effects of sphingosine, C₂-ceramide inhibits proliferation of normal differentiated cells as well as normal stem cells, tumorigenic cells, and MCF7 cancer cells with similar potency. Both sphingosine and C₂-ceramide induce apoptosis in tumorigenic cells. Among the sphingosine stereoisomers (D-erythro, D-threo, L-erythro, and L-threo) and sphinganine that were tested, L-erythro-sphingosine most potently inhibits proliferation of tumorigenic cells. The inhibition of breast tumorigenic/cancer cell proliferation by sphingosine was accompanied by inhibition of telomerase activity. Sphingosine at non-cytotoxic concentrations, but not C₂-ceramide, induces differentiation of normal stem cells (Type I), thereby reducing the number of stem cells that are more susceptible to neoplastic transformation. To the best of our knowledge, the present study demonstrates one of the first results that sphingosine can be a potential chemotherapeutic and cancer-protective agent, whereas C₂-ceramide is not an ideal chemotherapeutic and cancer-protective agent due to its anti-proliferative effects on Type II HBECs and its inability to induce the differentiation of Type I to Type II HBECs.

Persistent increase in ecto‑5'‑nucleotidase activity from encephala of adult zebrafish exposed to ethanol during early development

Prenatal alcohol exposure causes alterations to the brain and can lead to numerous cognitive and behavioral outcomes. Long-lasting effects of early ethanol exposure have been registered in glutamatergic and dopaminergic systems. The purinergic system has been registered as an additional target of ethanol exposure. The objective of this research was to evaluate if the ecto‑5'‑nucleotidase and adenosine deaminase activities and gene expression of adult zebrafish exposed to 1% ethanol during early development could be part of the long-lasting targets of ethanol. Zebrafish embryos were exposed to 1% ethanol in two distinct developmental phases: gastrula/segmentation (5-24 h post-fertilization) or pharyngula (24-48 h post-fertilization). At the end of three months, after checking for morphological outcomes, the evaluation of enzymatic activity and gene expression was performed. Exposure to ethanol did not promote gross morphological defects; however, a significant decrease in the body length was observed (17% in the gastrula and 22% in the pharyngula stage, p < 0.0001). Ethanol exposure during the gastrula/segmentation stage promoted an increase in ecto‑5'‑nucleotidase activity (39.5%) when compared to the control/saline group (p < 0.0001). The ecto‑5'‑nucleotidase gene expression and the deamination of adenosine exerted by ecto and cytosolic adenosine deaminase were not affected by exposure to ethanol in both developmental stages. HPLC experiments did not identify differences in adenosine concentration on the whole encephala of adult animals exposed to ethanol during the gastrula stage or on control animals (p > 0.05). Although the mechanism underlying these findings requires further investigation, these results indicate that ethanol exposure during restricted periods of brain development can have long-term consequences on ecto‑5'‑nucleotidase activity, which could have an impact on subtle sequels of ethanol early exposure.

Early exposure to ethanol is able to affect the memory of adult zebrafish: Possible role of adenosine

Ethanol is one of the most widely consumed drugs in the world, and the effects of ethanol during early development include morphological and cognitive problems. The regulation of adenosine levels is essential for the proper function of major neurotransmitter systems in the brain, particularly glutamate and dopamine; thus, the investigation of the relation of adenosine and memory after early ethanol exposure becomes relevant. Embryos of zebrafish were exposed to 1% ethanol during two distinct developmental stages: gastrula/segmentation or pharyngula. The evaluation of memory, morphology, and locomotor parameters was performed when fish were 3 months old. The effect of ecto-5'-nucleotidase and adenosine deaminase inhibition on the consequences of ethanol exposure with regard to memory formation was observed. Morphological evaluation showed decreases in body length and the relative telencephalic and cerebellar areas in ethanol exposed animals. The locomotor parameters evaluated were not affected by ethanol. In the inhibitory avoidance paradigm, ethanol exposure during the gastrula/segmentation and pharyngula stages decreased zebrafish memory retention. When ethanol was given in the pharyngula stage, the inhibition of ecto-5'-nucleotidase in the acquisition phase of memory tests was able to revert the effects of ethanol on the memory of adults. These findings suggest that the increased adenosine levels caused by ethanol could alter the neuromodulation of important components of memory formation, such as neurotransmitters. The adjustment of adenosine levels through ecto-5'-nucleotidase inhibition appears to be effective at restoring normal adenosine levels and the acquisition of memory in animals exposed to ethanol during the pharyngula stage.

PITX2 Enhances the Regenerative Potential of Dystrophic Skeletal Muscle Stem Cells

Duchenne muscular dystrophy (DMD), one of the most lethal genetic disorders, involves progressive muscle degeneration resulting from the absence of DYSTROPHIN. Lack of DYSTROPHIN expression in DMD has critical consequences in muscle satellite stem cells including a reduced capacity to generate myogenic precursors. Here, we demonstrate that the c-isoform of PITX2 transcription factor modifies the myogenic potential of dystrophic-deficient satellite cells. We further show that PITX2c enhances the regenerative capability of mouse DYSTROPHIN-deficient satellite cells by increasing cell proliferation and the number of myogenic committed cells, but importantly also increasing dystrophin-positive (revertant) myofibers by regulating miR-31. These PITX2-mediated effects finally lead to improved muscle function in dystrophic (DMD/mdx) mice. Our studies reveal a critical role for PITX2 in skeletal muscle repair and may help to develop therapeutic strategies for muscular disorders.

Chronic binge alcohol consumption alters myogenic gene expression and reduces in vitro myogenic differentiation potential of myoblasts from rhesus macaques

Chronic alcohol abuse is associated with skeletal muscle myopathy. Previously, we demonstrated that chronic binge alcohol (CBA) consumption by rhesus macaques accentuates skeletal muscle wasting at end-stage of simian immunodeficiency virus (SIV) infection. A proinflammatory, prooxidative milieu and enhanced ubiquitin proteasome activity were identified as possible mechanisms leading to loss of skeletal muscle. The possibility that impaired regenerative capacity, as reflected by the ability of myoblasts derived from satellite cell (SCs) to differentiate into myotubes has not been examined. We hypothesized that the inflammation and oxidative stress in skeletal muscle from CBA animals impair the differentiation capacity of myoblasts to form new myofibers in in vitro assays. We isolated primary myoblasts from the quadriceps femoris of rhesus macaques that were administered CBA or isocaloric sucrose (SUC) for 19 mo. Proliferation and differentiation potential of cultured myoblasts were examined in vitro. Myoblasts from the CBA group had significantly reduced PAX7, MYOD1, MYOG, MYF5, and MEF2C expression. This was associated with decreased myotube formation as evidenced by Jenner-Giemsa staining and myonuclei fusion index. No significant difference in the proliferative ability, cell cycle distribution, or autophagy was detected between myoblasts isolated from CBA and SUC groups. Together, these results reflect marked dysregulation of myoblast myogenic gene expression and myotube formation, which we interpret as evidence of impaired skeletal muscle regenerative capacity in CBA-administered macaques. The contribution of this mechanism to alcoholic myopathy warrants further investigation.

Chronic alcohol ingestion delays skeletal muscle regeneration following injury

Background

Chronic alcohol ingestion may cause severe biochemical and pathophysiological derangements to skeletal muscle. Unfortunately, these alcohol-induced events may also prime skeletal muscle for worsened, delayed, or possibly incomplete repair following acute injury. As alcoholics may be at increased risk for skeletal muscle injury, our goals were to identify the effects of chronic alcohol ingestion on components of skeletal muscle regeneration. To accomplish this, age- and gender-matched C57Bl/6 mice were provided normal drinking water or water that contained 20% alcohol (v/v) for 18–20 wk. Subgroups of mice were injected with a 1.2% barium chloride (BaCl₂) solution into the tibialis anterior (TA) muscle to initiate degeneration and regeneration processes. Body weights and voluntary wheel running distances were recorded during the course of recovery. Muscles were harvested at 2, 7 or 14 days post-injection and assessed for markers of inflammation and oxidant stress, fiber cross-sectional areas, levels of growth and fibrotic factors, and fibrosis.

Results

Body weights of injured, alcohol-fed mice were reduced during the first week of recovery. These mice also ran significantly shorter distances over the two weeks following injury compared to uninjured, alcoholics. Injured TA muscles from alcohol-fed mice had increased TNFα and IL6 gene levels compared to controls 2 days after injury. Total protein oxidant stress and alterations to glutathione homeostasis were also evident at 7 and 14 days after injury. Ciliary neurotrophic factor (CNTF) induction was delayed in injured muscles from alcohol-fed mice which may explain, in part, why fiber cross-sectional area failed to normalize 14 days following injury. Gene levels of TGFβ₁ were induced early following injury before normalizing in muscle from alcohol-fed mice compared to controls. However, TGFβ₁ protein content was consistently elevated in injured muscle regardless of diet. Fibrosis was increased in injured, muscle from alcohol-fed mice at 7 and 14 days of recovery compared to injured controls.

Conclusions

Chronic alcohol ingestion appears to delay the normal regenerative response following significant skeletal muscle injury. This is evidenced by reduced cross-sectional areas of regenerated fibers, increased fibrosis, and altered temporal expression of well-described growth and fibrotic factors.

Notch pathway activation contributes to inhibition of C2C12 myoblast differentiation by ethanol

The loss of muscle mass in alcoholic myopathy may reflect alcohol inhibition of myogenic cell differentiation into myotubes. Here, using a high content imaging system we show that ethanol inhibits C2C12 myoblast differentiation by reducing myogenic fusion, creating smaller and less complex myotubes compared with controls. Ethanol administration during C2C12 differentiation reduced MyoD and myogenin expression, and microarray analysis identified ethanol activation of the Notch signaling pathway target genes Hes1 and Hey1. A reporter plasmid regulated by the Hes1 proximal promoter was activated by alcohol treatment in C2C12 cells. Treatment of differentiating C2C12 cells with a gamma secretase inhibitor (GSI) abrogated induction of Hes1. On a morphological level GSI treatment completely rescued myogenic fusion defects and partially restored other myotube parameters in response to alcohol. We conclude that alcohol inhibits C2C12 myoblast differentiation and the inhibition of myogenic fusion is mediated by Notch pathway activation.

Ethanol, acetaldehyde, and estradiol affect growth and differentiation of rhesus monkey embryonic stem cells

BACKGROUND

The timing of the origins of fetal alcohol syndrome has been difficult to determine, in part because of the challenge associated with in vivo studies of the peri-implantation stage of embryonic development. Because embryonic stem cells (ESCs) are derived from blastocyst stage embryos, they are used as a model for early embryo development.

METHODS

Rhesus monkey ESC lines (ORMES-6 and ORMES-7) were treated with 0, 0.01, 0.1, or 1.0% ethanol, 1.0% ethanol with estradiol, or 0.00025% acetaldehyde with or without estradiol for 4 weeks.

RESULTS

Although control ESCs remained unchanged, abnormal morphology of ESCs in the ethanol and acetaldehyde treatment groups was observed before 2 weeks of treatment. Immunofluorescence staining of key pluripotency markers (TRA-1-81 and alkaline phosphatase) indicated a loss of ESC pluripotency in the 1.0% ethanol group. ORMES-7 was more sensitive to effects of ethanol than ORMES-6.

CONCLUSIONS

Estradiol appeared to increase sensitivity to ethanol in the ORMES-6 and ORMES-7 cell line. The morphological changes and labeling for pluripotency, proliferation, and apoptosis demonstrated that how ethanol affects these early cells that develop in culture, their differentiation state in particular. The effects of ethanol may be mediated in part through metabolic pathways regulating acetaldehyde formation, and while potentially accentuated by estradiol in some individuals, how remains to be determined.

Ethanol decreases agrin-induced acetylcholine receptor clustering in C2C12 myotube culture

We investigated the effect of ethanol on skeletal muscle development using C2C12 cell culture. The ethanol concentrations of 10mM, 25mM, and 100mM, were tested because plasma samples of alcohol-dependent individuals fall within this range. We assessed two specific events in skeletal muscle development, the fusion of myoblasts to form myotubes and the acetylcholine receptor (AChR) clustering associated with neuromuscular synapse formation. We report that ethanol does not effect myotube formation or the viability of myoblasts or myotubes in C2C12 cell culture. However, ethanol does effect AChR clustering on C2C12 myotubes. As motor neurons approach skeletal muscle during development, agrin is released by motor neurons and induces AChR clustering on muscle fibers. In our experiments, agrin was applied to cell cultures during the period when myoblasts fuse to form myotubes. In cell cultures exposed to ethanol during myotube formation, agrin-induced AChR clustering was decreased compared to untreated cultures. In cell cultures exposed to ethanol during myoblast proliferation, with ethanol removed during myotube formation, agrin-induced AChR clustering was unaffected. We conclude that exposure to a physiologically relevant concentration of ethanol during the specific period of myotube formation decreases agrin-induced AChR clustering.

The effects of solvents on embryonic stem cell differentiation

Dimethyl sulfoxide (DMSO) and ethanol are common organic solvents used for dissolving lipophilic substances for in vitro testing. However, DMSO is known to induce differentiation in embryonic stem (ES) and embryonic teratocarcinoma (EC) cells. In order to clarify if solvents like DMSO and ethanol have an influence on in vitro developmental toxicity test systems, the presented study has evaluated their effects on differentiation by using different test systems. ES and EC cells were transfected with a construct containing the mTert promoter combined with the green fluorescent protein gene (GFP). A down-regulation of mTert, a marker for undifferentiated cells, results in a lower expression of GFP, which could be measured by flow cytometry. Taking the specific characteristics of ES and EC cells into account this effect could be a hint for the interaction of DMSO with embryonic development. Additionally, the effects of the solvents ethanol and DMSO on Oct-4 expression, another marker for undifferentiated cells, were measured in wild-type ES cells. Both selected molecular markers demonstrated an induction of differentiation after exposure to DMSO; in wild-type ES cells at a concentration of 0.125% and in transgenic EC cells at a concentration of 0.25% DMSO. All other differences from controls, including those which attained a level of statistical significance, were minor or not dosage related in degree, or were not consistent over time and are, therefore, considered to be of little toxicological importance. In addition, a cytotoxicity test demonstrated that the solvents affected the employed molecular markers in non-cytotoxic concentrations. The ES cells were the most sensitive towards the cytotoxic effects of the solvent DMSO while the EC cells were more sensitive when treated with the solvent ethanol.

The Detection of Differentiation-inducing Chemicals by using Green Fluorescent Protein Expression in Genetically Engineered Teratocarcinoma Cells

The murine embryonal teratocarcinoma cell line, P19, was genetically manipulated in order to provide preliminary information on compounds that induce differentiation. Without chemical induction, P19 cells remain in an undifferentiated state, but can be induced to differentiate into specific cell types. For example, dimethyl sulphoxide (DMSO) induces cardiac and skeletal muscle differentiation, whereas retinoic acid stimulates neuronal differentiation. P19 cells were transfected with a construct containing a segment of the murineTert (mTert) promoter sequence combined with the green fluorescent protein (GFP) gene, which acts as a reporter gene. mTert expression, the reverse transcriptase component of murine telomerase, is closely linked to telomerase activity and is down-regulated during differentiation. Three retinoids and DMSO induced the differentiation of P19 cells, which was determined by a reduction in mTert_GFP expression, detected by flow cytometry and confocal microscopy as independent methods of detection. A test substance, ethanol, and a control substance, saccharin, did not cause a decrease in mTert_GFP expression. In addition, it could be demonstrated that the mTert_GFP test detects developmentally relevant effects at non-cytotoxic concentrations. The ID50 values derived for the reduction of mTert_GFP expression were lower than the IC50 values detected with the MTT test, by a factor of 21.4 for all-trans retinoic acid, 12.7 for 9-cis retinoic acid, 29.6 for 13-cis retinoic acid, and 8.7 for DMSO. In comparison to the IC50 value for the P19 cell line, a similar IC50 value was obtained with 3T3 cells for ethanol, but there was a 2-fold increase for DMSO. The retinoids were not cytotoxic to 3T3 cells at the concentrations tested. This newly developed test is capable of detecting differentiation-inducing compounds at non-cytotoxic concentrations within 4 days. It offers a method for detecting chemicals with specific toxicological mechanisms, such as the retinoids, which could provide additional information in embryotoxicity testing as different promoters could be employed. Here, we report the use of this novel test system for the successful analysis of DMSO and three retinoids with different in vivo teratogenic potentials.

Metabolic effects of ethanol on primary cell cultures of rat skeletal muscle

Individuals who have consumed alcohol chronically accumulate glycogen in their skeletal muscles. Changes in the energy balance caused by alcohol consumption might lead to alcoholic myopathy. Experimental models used in the past, such as with skeletal muscle biopsy samples of alcohol-dependent individuals or in animal models, do not distinguish between direct effects and indirect effects (i.e., alterations to the nervous or endocrine system) of alcohol. In the current study, we evaluated the direct effect of ethanol on skeletal muscle glycogen concentrations and related glycolytic pathways. We measured the changes in metabolite concentrations and enzyme activities of carbohydrate metabolism in primary cell cultures of rat skeletal muscle exposed to ethanol for two periods. The concentrations of glycolytic metabolites and the activities of several enzymes that regulate glucose and glycogen metabolism were measured. After a short exposure to ethanol (6 h), glucose metabolism slowed. After 48 h of exposure, glycogen accumulation was observed.

Moderate alcohol intake has no impact on acute and chronic progressive anti-thy1 glomerulonephritis

Moderate alcohol consumption has shown beneficial effects in experimental and human cardiovascular disease. With the use of rat models of acute and chronic progressive anti-thy1 glomerulonephritis (GN), we tested the hypothesis that moderate alcohol intake is protective in renal fibrotic disease. In acute anti-thy1 GN, untreated nephritic rats showed marked mesangial cell lysis and induced nitric oxide production at day 1 and high proteinuria, glomerular matrix accumulation, and transforming growth factor (TGF)-beta(1), fibronectin, and plasminogen activator inhibitor (PAI)-1 expression at day 7 after disease induction, respectively. In animals 15 wk after induction of chronic progressive anti-thy1 GN, disease was characterized by significantly reduced renal function, persisting albuminuria as well as increased glomerular and tubulointerstitial matrix expansion, TGF-beta(1), fibronectin, and PAI-1 protein expression. In both anti-thy1 GN models, an ethanol intake of approximately 2 ml per day and animal was achieved, however, disease severity was not significantly altered by moderate alcohol consumption in any of the protocols. In conclusion, moderate alcohol intake does not influence renal matrix protein production and accumulation in acute and chronic progressive anti-thy1 glomerulofibrosis. The study suggests that, in contrast to cardiovascular disorders, moderate alcohol consumption might not provide specific protection in renal fibrotic disease.

Alcoholic myopathy: biochemical mechanisms

Between one- and two-thirds of all alcohol abusers have impairment of muscle function that may be accompanied by biochemical lesions and/or the presence of a defined myopathy characterised by selective atrophy of Type II fibres. Perturbations in protein metabolism are central to the effects on muscle and account for the reductions in muscle mass and fibre diameter. Ethanol abuse is also associated with abnormalities in carbohydrate (as well as lipid) metabolism in skeletal muscle. Ethanol-mediated insulin resistance is allied with the inhibitory effects of ethanol on insulin-stimulated carbohydrate metabolism. It acutely impairs insulin-stimulated glucose and lipid metabolism, although it is not known whether it has an analogous effect on insulin-stimulated protein synthesis. In alcoholic cirrhosis, insulin resistance occurs with respect to carbohydrate metabolism, although the actions of insulin to suppress protein degradation and stimulate amino acid uptake are unimpaired. In acute alcohol-dosing studies defective rates of protein synthesis occur, particularly in Type II fibre-predominant muscles. The relative amounts of mRNA-encoding contractile proteins do not appear to be adversely affected by chronic alcohol feeding, although subtle changes in muscle protein isoforms may occur. There are also rapid and sustained reductions in total (largely ribosomal) RNA in chronic studies. Loss of RNA appears to be related to increases in the activities of specific muscle RNases in these long-term studies. However, in acute dosing studies (less than 1 day), the reductions in muscle protein synthesis are not due to overt loss of total RNA. These data implicate a role for translational modifications in the initial stages of the myopathy, although changes in transcription and/or protein degradation may also be superimposed. These events have important implications for whole-body metabolism.