Progress in microglia-mediated neuroinflammation and synaptic pruning in autism spectrum disorder
[Background]Autism spectrum disorder(ASD)is a group of neurodevelopmental disorders characterized by deficits in social interactions and repetitive behaviors,accompanied by some related issues such as intellectual disability,anxiety,depression,sleep deficits,attention deficit and hyperactivity disorder,seizures,and obsessive-compulsive disorder.A large number of studies have shown that various genetic,epigenetic modification and environmental factors contribute to the etiology and development of ASD.However,the precise mechanisms underlying ASD have yet to be elucidated.[Progress]In recent years,the role of microglia in ASD has received increasing attention.Microglia not only mediate neuroinflammation in response to stimulus but also regulate brain development and neural circuits through synaptic pruning.Microglial activation and increased neuroinflammation have been observed in both ASD postmortem brain tissues and animal models,suggesting that the activation of microglia may contribute to the pathology and behavioral abnormalities of ASD.Moreover,increasing evidence suggests that abnormal microglia also contribute to ASD through dysregulating synaptic formation.Although microglia are found to be aberrantly activated in the ASD brain,dendritic spine density is found to be higher in ASD patients than that in control healthy group.The increased spine density may be attributed to the reduced capacity of synaptic pruning by microglia.Several molecular signals,such as complement pathways,triggering receptor expressed on myeloid cells 2(TREM2)and C-X3-C motif chemokine receptor 1-ligand 1(CX3CR1-CX3CL1)axis,participate in microglial synaptic pruning and are found to be abnormally expressed in the individuals with ASD.Previous studies have demonstrated that dysregulation of these signals leads to impaired synaptic pruning and ASD-like behaviors in mice.However,whether there is a direct association between microglia-mediated neuroinflammation and synaptic pruning remains to be explored.This comprehensive review summarizes the current findings about microglia-mediated neuroinflammation and synaptic function in ASD.[Perspective]The etiology of ASD is not solely attributed to neuronal abnormality.Emerging evidence indicates that microglial dysfunction also plays a crucial role in the etiology and development of ASD.Abnormal activation of microglia and increased neuroinflammation are found in the brains of patients with ASD and contribute to the development of the disease.Synaptic pruning by microglia is necessary for synaptic maturation and plasticity during the early brain neurodevelopment.Aberrant synaptic pruning in ASD can also lead to changes in the number and function of synapses.This review provides a deeper understanding of the association between microglial dysfunction and ASD.So far,the correlation between neuroinflammatory responses and the abnormal synaptic regulation mediated by microglia in ASD remains uncertain and requires detailed investigation.Further study on the molecular mechanisms underlying microglia dysfunction-induced ASD,such as identifying risk genes of ASD in microglia using modern techniques like single-cell sequencing,will provide better guidance for the clinical diagnosis and therapeutic strategy for ASD.
国家科技期刊平台
NSTL
万方数据
