The Immune System in Autism

Inhibition of Trpv4 rescues circuit and social deficits unmasked by acute inflammatory response in a Shank3 mouse model of Autism

Mutations in the SHANK3 gene have been recognized as a genetic risk factor for Autism Spectrum Disorder (ASD), a neurodevelopmental disease characterized by social deficits and repetitive behaviors. While heterozygous SHANK3 mutations are usually the types of mutations associated with idiopathic autism in patients, heterozygous deletion of Shank3 gene in mice does not commonly induce ASD-related behavioral deficit. Here, we used in-vivo and ex-vivo approaches to demonstrate that region-specific neonatal downregulation of Shank3 in the Nucleus Accumbens promotes D1R-medium spiny neurons (D1R-MSNs) hyperexcitability and upregulates Transient Receptor Potential Vanilloid 4 (Trpv4) to impair social behavior. Interestingly, genetically vulnerable Shank3^+/- mice, when challenged with Lipopolysaccharide to induce an acute inflammatory response, showed similar circuit and behavioral alterations that were rescued by acute Trpv4 inhibition. Altogether our data demonstrate shared molecular and circuit mechanisms between ASD-relevant genetic alterations and environmental insults, which ultimately lead to sociability dysfunctions.

Diffusion tensor imaging findings in school-aged autistic children

OBJECTIVE

To analyze and compare cerebral white matter tracts through diffusion tensor imaging in autistic and normal children.

METHODS

This is a case-control study on a sample of eight male, right-handed children diagnosed with autism according to Diagnostic and Statistical Manual of Mental Disorders-4th Edition criteria, and eight healthy age- and sex-matched controls. Imaging studies were performed on a 1.5-T scanner (Symphony Maestro Class, Siemens, Erlangen, Germany). Fractional anisotropy was calculated for the frontopontine and corticospinal tracts, frontal subcortical white matter, anterior cingulate, corpus callosum, striatum, internal capsule, optic radiation, superior and inferior longitudinal fascicles, and cerebellum. Analysis of significance was based on analysis of variance test for the mean fractional anisotropy values.

RESULTS

Median age of cases was 9.53 +/- 1.83 years, and of controls, 9.57 +/- 1.36 years. Diffusion tensor imaging findings included significant reduction of fractional anisotropy in the anterior corpus callosum (P= .008), right corticospinal tract (P= .044), posterior limb of right and left internal capsules (P= .003 and .049, respectively), left superior cerebellar peduncle (P= .031), and right and left middle cerebellar peduncles (P= .043 and .039, respectively) in autistic children.

CONCLUSIONS

The diffusion tensor imaging findings in children with autistic disorder suggest impairment of white matter microstructure, possibly associated with reduced connectivity in corpus callosum, internal capsule, and superior and middle cerebellar peduncles.