Variability of Creatine Metabolism Genes in Children with Autism Spectrum Disorder

Upregulation and epigenetic modification of the creatine transporter SLC6A8 in non-small cell lung cancer

INTRODUCTION

Lung cancer is a major cause of cancer-related death worldwide and effective therapies, besides surgery, are available only for a small proportion of patients. Since cellular respiration is known to be broadly altered in malignant tumors, the cellular processes of respiration can be a potential therapeutic target. One important element of cellular respiration is creatine and its transport by the creatine transporter SLC6A8. Here we describe the expression of SLC6A8 at the RNA and protein level, epigenetic modifications as well as survival analysis in NSCLC tissues and matched controls.

MATERIALS AND METHODS

We analyzed epigenetic modifications of the SLC68A gene in 32 patients, of which 18 were additionally analyzed by transcriptome analysis. The expression of SLC6A8 at the protein level was assessed by immunohistochemistry using an independent cohort and correlated with clinicopathological data including survival. Kaplan-Meier analysis was performed to analyze the possible effects of the transcriptional levels of SLC6A8 in another separate cohort (n=1925).

RESULTS

SLC6A8 loci are epigenetically modified in NSCLC compared with tumor-free controls. SLC6A8 is upregulated in NSCLC at the RNA and protein level. High mRNA expression of SLC6A8 was associated with an overall poor prognosis in lung adenocarcinoma patients and displayed the strongest adverse prognostic effect in male smokers with adenocarcinomas. Results of transcriptome analysis were partially confirmed at the protein level.

CONCLUSIONS

Our results suggest an important role of creatine and its transport via SLC6A8 in NSCLC.

Rare disease variant curation from literature: assessing gaps with creatine transport deficiency in focus

BACKGROUND

Approximately 4-8% of the world suffers from a rare disease. Rare diseases are often difficult to diagnose, and many do not have approved therapies. Genetic sequencing has the potential to shorten the current diagnostic process, increase mechanistic understanding, and facilitate research on therapeutic approaches but is limited by the difficulty of novel variant pathogenicity interpretation and the communication of known causative variants. It is unknown how many published rare disease variants are currently accessible in the public domain.

RESULTS

This study investigated the translation of knowledge of variants reported in published manuscripts to publicly accessible variant databases. Variants, symptoms, biochemical assay results, and protein function from literature on the SLC6A8 gene associated with X-linked Creatine Transporter Deficiency (CTD) were curated and reported as a highly annotated dataset of variants with clinical context and functional details. Variants were harmonized, their availability in existing variant databases was analyzed and pathogenicity assignments were compared with impact algorithm predictions. 24% of the pathogenic variants found in PubMed articles were not captured in any database used in this analysis while only 65% of the published variants received an accurate pathogenicity prediction from at least one impact prediction algorithm.

CONCLUSIONS

Despite being published in the literature, pathogenicity data on patient variants may remain inaccessible for genetic diagnosis, therapeutic target identification, mechanistic understanding, or hypothesis generation. Clinical and functional details presented in the literature are important to make pathogenicity assessments. Impact predictions remain imperfect but are improving, especially for single nucleotide exonic variants, however such predictions are less accurate or unavailable for intronic and multi-nucleotide variants. Developing text mining workflows that use natural language processing for identifying diseases, genes and variants, along with impact prediction algorithms and integrating with details on clinical phenotypes and functional assessments might be a promising approach to scale literature mining of variants and assigning correct pathogenicity. The curated variants list created by this effort includes context details to improve any such efforts on variant curation for rare diseases.

Global metabolic profiles in a non-human primate model of maternal immune activation: implications for neurodevelopmental disorders

Epidemiological evidence implicates severe maternal infections as risk factors for neurodevelopmental disorders, such as ASD and schizophrenia. Accordingly, animal models mimicking infection during pregnancy, including the maternal immune activation (MIA) model, result in offspring with neurobiological, behavioral, and metabolic phenotypes relevant to human neurodevelopmental disorders. Most of these studies have been performed in rodents. We sought to better understand the molecular signatures characterizing the MIA model in an organism more closely related to humans, rhesus monkeys (Macaca mulatta), by evaluating changes in global metabolic profiles in MIA-exposed offspring. Herein, we present the global metabolome in six peripheral tissues (plasma, cerebrospinal fluid, three regions of intestinal mucosa scrapings, and feces) from 13 MIA and 10 control offspring that were confirmed to display atypical neurodevelopment, elevated immune profiles, and neuropathology. Differences in lipid, amino acid, and nucleotide metabolism discriminated these MIA and control samples, with correlations of specific metabolites to behavior scores as well as to cytokine levels in plasma, intestinal, and brain tissues. We also observed modest changes in fecal and intestinal microbial profiles, and identify differential metabolomic profiles within males and females. These findings support a connection between maternal immune activation and the metabolism, microbiota, and behavioral traits of offspring, and may further the translational applications of the MIA model and the advancement of biomarkers for neurodevelopmental disorders such as ASD or schizophrenia.

Dog Therapy in Supporting the Rehabilitation Process of Children with Autism

Introduction: Autism is not a specific condition. It is, however, a comprehensive disorder of psychomotor and social development. A number of factors, both environmental (family-related) and genetic, are believed to be the cause of autism. The percentage of children affected by autism has been increasing over the past 20 years. It is assumed that statistically, approximately 20 children in every 10,000 will become affected by this condition. Autism is 4 times more common in boys than in girls. The disorder is characterised by impaired mental growth, and, consequently, social and motor development. Research objective: The aim of the article is to present the role of dog therapy in supporting the process of therapeutic rehabilitation among children with autism. In particular, the following aspects were taken into account: breeds of canines used in dog therapy, mechanisms of influence concerning dog therapy on the child's body, as well as the forms and results obtained. Material and methods: The work is a narrative review. It was written on the basis of the document analysis method with the use of quantitative and qualitative techniques, as well as database searches for Polish and foreign scientific literature on the subject, i.e. Web of Science, PubMed and Google Scholar. In the article, the research results are presented in relation to the efficiency of applying dog therapy in the treatment of autistic children between 2002 and 2017, with emphasis on foreign literature. Results: The most commonly used forms of dog therapy used are: Animal Assisted Activity (AAA), Animal Assisted Therapy (AAT) and Animal Assisted Education (AAE). Conclusions: The use of dogs in the process of therapeutic rehabilitation has positive influence both on the autistic child and his/her family environment. It helps cope better with many difficulties and motivates to take up more activities. Dog therapy affects all spheres of personal development, i.e. mental, motor and socio-emotional.

Decreased in vivo glutamate/GABA ratio correlates with the social behavior deficit in a mouse model of autism spectrum disorder

To diagnose autism spectrum disorder (ASD), researchers have sought biomarkers whose alterations correlate with the susceptibility to ASD. However, biomarkers closely related to the pathophysiology of ASD are lacking. Even though excitation/inhibition (E/I) imbalance has been suggested as an underlying mechanism of ASD, few studies have investigated the actual ratio of glutamate (Glu) to γ-aminobutyric acid (GABA) concentration in vivo. Moreover, there are controversies in the directions of E/I ratio alterations even in extensively studied ASD animal models. Here, using proton magnetic resonance spectroscopy (¹H-MRS) at 9.4T, we found significant differences in the levels of different metabolites or their ratios in the prefrontal cortex and hippocampus of Cntnap2^−/− mice compared to their wild-type littermates. The Glu/GABA ratio, N-acetylaspartate (NAA)/total creatine (tCr) ratio, and tCr level in the prefrontal cortex were significantly different in Cntnap2^−/− mice compared to those in wild-type mice, and they significantly correlated with the sociability of mice. Moreover, receiver operating characteristic (ROC) analyses indicated high specificity and selectivity of these metabolites in discriminating genotypes. These results suggest that the lowered Glu/GABA ratio in the prefrontal cortex along with the changes in the other metabolites might contribute to the social behavior deficit in Cntnap2^−/− mice. Our results also demonstrate the utility of ¹H-MRS in investigating the underlying mechanisms or the diagnosis of ASD.

Creatine in Health and Disease

Although creatine has been mostly studied as an ergogenic aid for exercise, training, and sport, several health and potential therapeutic benefits have been reported. This is because creatine plays a critical role in cellular metabolism, particularly during metabolically stressed states, and limitations in the ability to transport and/or store creatine can impair metabolism. Moreover, increasing availability of creatine in tissue may enhance cellular metabolism and thereby lessen the severity of injury and/or disease conditions, particularly when oxygen availability is compromised. This systematic review assesses the peer-reviewed scientific and medical evidence related to creatine's role in promoting general health as we age and how creatine supplementation has been used as a nutritional strategy to help individuals recover from injury and/or manage chronic disease. Additionally, it provides reasonable conclusions about the role of creatine on health and disease based on current scientific evidence. Based on this analysis, it can be concluded that creatine supplementation has several health and therapeutic benefits throughout the lifespan.

A bigger brain for a more complex environment

The environment increased complexity required more neural functions to develop in the hominin brains, and the hominins adapted to the complexity by developing a bigger brain with a greater interconnection between its parts. Thus, complex environments drove the growth of the brain. In about two million years during hominin evolution, the brain increased three folds in size, one of the largest and most complex amongst mammals, relative to body size. The size increase has led to anatomical reorganization and complex neuronal interactions in a relatively small skull. At birth, the human brain is only about 20% of its adult size. That facilitates the passage through the birth canal. Therefore, the human brain, especially cortex, develops postnatally in a rich stimulating environment with continuous brain wiring and rewiring and insertion of billions of new neurons. One of the consequence is that in the newborn brain, neuroplasticity is always turned "on" and it remains active throughout life, which gave humans the ability to adapt to complex and often hostile environments, integrate external experiences, solve problems, elaborate abstract ideas and innovative technologies, store a lot of information. Besides, hominins acquired unique abilities as music, language, and intense social cooperation. Overwhelming ecological, social, and cultural challenges have made the human brain so unique. From these events, as well as the molecular genetic changes that took place in those million years, under the pressure of natural selection, derive the distinctive cognitive abilities that have led us to complex social organizations and made our species successful.

The Autism Treatment Network: Bringing Best Practices to All Children With Autism

The Autism Treatment Network and Autism Intervention Research Network on Physical Health were established in 2008 with goals of improving understanding of the medical aspects of autism spectrum disorders. Over the past decade, the combined network has conducted >2 dozen clinical studies, established clinical pathways for best practice, developed tool kits for professionals and families to support better care, and disseminated these works through numerous presentations at scientific meetings and publications in medical journals. As the joint network enters its second decade continuing this work, it is undergoing a transformation to increase these activities and accelerate their incorporation into clinical care at the primary care and specialty care levels. In this article, we describe the past accomplishments and present activities. We also outline planned undertakings such as the establishment of the Autism Learning Health Network, the increasing role of family members as co-producers of the work of the network, the growth of clinical trials activities with funding from foundations and industry, and expansion of work with primary care practices and autism specialty centers. We also discuss the challenges of supporting network activities and potential solutions to sustain the network.

Identification of gender-related metabolic disturbances in autism spectrum disorders using urinary metabolomics

Autism spectrum disorders (ASD) are a highly heterogeneous group of neurodevelopmental disorders that are more commonly diagnosed in boys than in girls. The reasons for gender differences in ASD are unknown and no definitive current evidence can explain male predominance. Therefore, in search for laboratory biomarkers responsible for ASD, a comprehensive metabolomics study was performed by metabolic profiling of urine samples in 51 ASD subjects and 51 age- and sex-matched children with typical development. Orthogonal partial least-squares discriminant analysis (OPLS-DA) models with poor quality failed to perform the analysis based on gender in the ASD and control groups. OPLS-DA models based on single-sex samples, especially in female subjects, had better clustering between the ASD and control groups with an increase in the R² and Q² values compared with those in the whole group. Significantly increased levels of adenine, 2-Methylguanosine, creatinine, and 7alpha-hydroxytestololactone and a decrease in creatine were observed in the female ASD subjects. In particular, 7alpha-hydroxytestololactone, which has a structure similar to that of testolactone, was positively correlated with adenine (Pearson correlation coefficient, r = 0.738, p < 0.01), creatinine (r = 0.826, p < 0.01), and 2-Methylguanosine (r = 0.757, p < 0.01) and negatively correlated with creatine (r=-0.413, p < 0.05). A receiver operating characteristic curve analysis using the creatinine:creatine ratio yielded an area under the curve of 0.913 (95% CI: 0.806-1). These metabolites may be sex-related or sex-sensitive to an extent and can be valuable for identification of the molecular pathways involved in the gender bias in manifestation of ASD. The creatinine:creatine ratio has a potential to be a good predictor of ASD in the female subjects.