Current knowledge, challenges, new perspectives of the study, and treatments of Autism Spectrum Disorder

The potential ameliorative effect of mesenchymal stem cells-derived exosomes on cerebellar histopathology and their modifying role on PI3k-mTOR signaling in rat model of autism spectrum disorder

Autism spectrum disorder (ASD) is a group of severe neurodevelopmental disorders. This study aimed to elucidate the potential ameliorating effect of postnatal administration of MSCs-derived Exo in a rat model of ASD. Male pups were divided into control (Cont), (VPA); pups of pregnant rats injected with VPA subcutaneously (S.C.) at embryonic day (ED) 13, and (VPA + Exo); pups were intravenously (I.V.) injected with MSCs-derived Exo either at postnatal day (P) 21 (adolescent VPA + Exo) or P70 (adult VPA + Exo). They were evaluated for physiological, histopathological and immunohistochemical changes of cerebellar structure, and genetic expression of PI3k and mTOR. The VPA adult group showed increased locomotor activity and impaired social activity, and anxiety. The cerebellar histological structure was disrupted in VPA groups. VPA + Exo groups showed preservation of the normal histological structure of the cerebellum. Immunohistochemical studies revealed enhanced expression of caspase-3, GFAP, Nestin, and VEGF in VPA groups beside modifying PI3K and mTOR genetic expression. MSCs-derived Exo ameliorated most of the rat cerebellar histopathological alterations and behavioral changes. Their mitigating effect could be established through their antiapoptotic, anti-inflammatory and anti-neurogenesis effect besides modifying PI3k-mTOR signaling.

Comparative effect of atorvastatin and risperidone on modulation of TLR4/NF-κB/NOX-2 in a rat model of valproic acid-induced autism

BACKGROUND

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that is significantly increasing, resulting in severe distress. The approved treatment for ASD only partially improves the sympoms, but it does not entirely reverse the symptoms. Developing novel disease-modifying drugs is essential for the continuous improvement of ASD. Because of its pleiotropic effect, atorvastatin has been garnered attention for treating neuronal degeneration. The present study aimed to investigate the therapeutic effects of atorvastatin in autism and compare it with an approved autism drug (risperidone) through the impact of these drugs on TLR4/NF-κB/NOX-2 and the apoptotic pathway in a valproic acid (VPA) induced rat model of autism.

METHODS

On gestational day 12.5, pregnant rats received a single IP injection of VPA (500 mg/kg), for VPA induced autism, risperidone and atorvastatin groups, or saline for control normal group. At postnatal day 21, male offsprings were randomly divided into four groups (n = 6): control, VPA induced autism, risperidone, and atorvastatin. Risperidone and atorvastatin were administered from postnatal day 21 to day 51. The study evaluated autism-like behaviors using the three-chamber test, the dark light test, and the open field test at the end of the study. Biochemical analysis of TLR4, NF-κB, NOX-2, and ROS using ELISA, RT-PCR, WB, histological examination with hematoxylin and eosin and immunohistochemical study of CAS-3 were performed.

RESULTS

Male offspring of prenatal VPA-exposed female rats exhibited significant autism-like behaviors and elevated TLR4, NF-κB, NOX-2, ROS, and caspase-3 expression. Histological analysis revealed structural alterations. Both risperidone and atorvastatin effectively mitigated the behavioral, biochemical, and structural changes associated with VPA-induced rat model of autism. Notably, atorvastatin group showed a more significant improvement than risperidone group.

CONCLUSIONS

The research results unequivocally demonstrated that atorvastatin can modulate VPA-induced autism by suppressing inflammation, oxidative stress, and apoptosis through TLR4/NF-κB/NOX-2 signaling pathway. Atorvastatin could be a potential treatment for ASD.

Bifidobacterium animalis subsp. lactis Probio-M8 alleviates abnormal behavior and regulates gut microbiota in a mouse model suffering from autism

Probiotics can effectively improve a variety of neurological diseases, but there is little research on autism, and the specific mechanism is unclear. In this study, shotgun metagenomics analysis was used to investigate the preventive and therapeutic effects of Bifidobacterium animalis subsp. lactis Probio-M8 on autism. The results showed that Probio-M8 treatment significantly alleviated valproate (VPA)-induced autism in mice, with autistic symptoms characterized by increased stereotyped behaviors such as grooming, reduced learning ability, and decreased desire to socialize. Further studies have found that Probio-M8 can alleviate autism by optimizing gut microbiota diversity and regulating metabolic levels. Probio-M8 regulates gut microbiota structure by increasing the abundance of beneficial bacteria such as Bifidobacterium globosum and Akkermansia muciniphila. In addition, Probio-M8 regulates metabolic activity by increasing levels of choline, which corrects CAZy disorders. In conclusion, Probio-M8 is therapeutic in the VPA-induced autism mouse model by regulating the gut microbiome and metabolic levels.IMPORTANCEIndividuals with autism often exhibit symptoms of social invariance, obsessive-compulsive tendencies, and repetitive behaviors. However, early intervention and treatment can be effective in improving social skills and mitigating autism symptoms, including behaviors related to irritability. Although taking medication for autism may lead to side effects such as weight gain, probiotics can be an ideal intervention for alleviating these symptoms. In this study, we investigated the effects of Probio-M8 intervention on the behavior of autistic mice using an open-field test, a three-chamber sociability test, and a novel object recognition test. Metagenomic analysis revealed differences in gut microbiota diversity among groups, predicted changes in metabolite levels, and functionally annotated CAZy. Additionally, we analyzed serum neurotransmitter levels and found that probiotics were beneficial in mitigating neurotransmitter imbalances in mice with autism.

Atorvastatin Improves the Propionic Acid-Induced Autism in Rats: The Roles of Sphingosine-1-Phosphate and Anti-inflammatory Action

Purpose The aim of this study is to investigate the benefits of atorvastatin on the propionic acid-induced autism model via increasing sphingosine-1-phosphate and anti-inflammatory actions with imaging and brain tissue investigations. Materials and methods Twenty-five mg/kg/day/rat of propionic acid (PPA) was administered intraperitoneally to 20 male Wistar rats, and 10 male Wistar rats were fed orally. Study groups were designed as follows: Group 1: Control Group (orally fed control, n=10); Group 2 (PPA+saline, n=10); Group 3 (PPA+Atorvastatin, n=10). The brain biochemical and histopathology assessments and magnetic resonance (MR) imaging were conducted across groups in order to compare them. Results The PPA+Atorvastatin group was found to have significantly lower levels of brain malondialdehyde, IL-2 level, IL-17, tumor necrosis factor-alpha (TNF-α), and lactate compared to the PPA+saline group. The PPA+Atorvastatin group had higher levels of nerve growth factor and nuclear factor erythroid 2-related factor 2 (NRF-2) and sphingosine-1-phosphate. In histopathology assessments, the PPA+Atorvastatin group was found to have significantly higher neuronal counts of CA1 and CA2 in the hippocampus, and Purkinje cells in the cerebellum. Conclusions Current findings suggest that atorvastatin increases sphingosine-1-phosphate levels and decreases inflammatory actions which characterize the autism rodent model implemented in this study. These preliminary results have to be confirmed by further experimental and clinical studies.

Genome-wide methylation analysis of post-mortem cerebellum samples supports the role of peroxisomes in autism spectrum disorder

Aim: We tested the hypothesis that a subset of patients with autism spectrum disorder (ASD) contains candidate genes with high DNA methylation differences (effective values) that potentially affect one of the two alleles. Materials & methods: Genome-wide DNA methylation comparisons were made on cerebellum samples from 30 patients and 45 controls. Results: 12 genes with high effective values, including GSDMD, MMACHC, SLC6A5 and NKX6-2, implicated in ASD and other neuropsychiatric disorders were identified. Monoallelic promoter methylation and downregulation were observed for SERHL (serine hydrolase-like) and CAT (catalase) genes associated with peroxisome function. Conclusion: These data are consistent with the hypothesis implicating impaired peroxisome function/biogenesis for ASD. A similar approach holds promise for identifying rare epimutations in ASD and other complex disorders.

Granulocyte Colony-Stimulating Factor Has a Sex-Dependent Positive Effect in the Maternal Immune Activation-Induced Autism Model

OBJECTIVE

The medical intervention for autism spectrum disorder (ASD) is restricted to ameliorating comorbid situations. Granulocyte colony-stimulating factor (G-CSF) is a growth factor that enhances the proliferation, differentiation and survival of hematopoietic progenitor cells. In the present study, we aimed to investigate the effects of G-CSF in a maternal immune activation-induced autism model.

METHODS

Sixteen female and 6 male Wistar adult rats were included in the study. After 21 days, forty-eight littermates (8 male controls, 8 female controls, 16 male lipopolysaccharide (LPS)-exposed rats and 16 female LPS-exposed rats) were divided into groups. Sixteen male LPS-exposed and 16 female LPS-exposed rats were divided into saline and G-CSF treatment groups.

RESULTS

In male rats, the LPS-exposed group was found to have significantly higher levels of TNF-α, IL-2, and IL-17 than the LPS-exposed G-CSF group. Levels of nerve growth factor, brain PSD-95 and brain GAD67 were higher in the LPS-exposed G-CSF group than in the LPS-exposed group in male rats. In female rats, brain NGF levels were similar between groups. There was no difference between groups in terms of brain GAD 67 levels. Brain PSD-95 levels were higher in the control group than in both the LPS-exposed and LPS-exposed G-CSF groups in female rats. Both neuronal CA1 and neuronal CA2 levels were lower, and the GFAP immunostaining index (CA1) and GFAP immunostaining index (CA3) were higher in the LPS-exposed group than in the LPS-exposed G-CSF group in male rats. However, neuronal count CA1 and Neuronal count CA3 values were found to be similar between groups in female rats.

CONCLUSIONS

The present research is the first to demonstrate the beneficial effects of G-CSF on core symptoms of ASD experimentally depending on male sex. G-CSF can be a good candidate for ameliorating the core symptoms of ASD without serious side effects in males.