Inhibition of tyrosine kinase signaling by tyrphostin AG126 downregulates the IL-21/IL-21R and JAK/STAT pathway in the BTBR mouse model of autism

Autism spectrum disorder (ASD) comprises a broad range of neurodevelopmental disorders that are associated with deficits in social interaction and communication. The tyrosine kinase inhibitor tyrphostin AG126 represents a promising therapeutic agent for several neuroinflammatory disorders. There are currently no treatments available that can improve ASD and we previously showed that AG126 treatment exerts beneficial effects on BTBR T⁺ Itpr3^tf/J (BTBR) mice, a model for autism that shows the core features of ASD; however, the immunological mechanisms and molecular targets associated with this effect were previously unclear. This study was undertaken to delineate the neuroprotective effect of AG126 on BTBR mice. Here, using this mouse model, we investigated the effects of AG126 administration on IL-21R, IL-21, IL-22, TNF-α, NOS2, STAT3, IL-27, and Foxp3 production by CD8⁺ T cells in the spleen by flow cytometry. We further explored the mRNA and protein expression of IL-21, IL-22, IL-1β, TNF-α, NOS2, JAK1, STAT3, IL-27, and Foxp3 in brain tissue by RT-PCR, and western blotting. We found that BTBR mice treated with AG126 exhibited significant decreases in IL-21R-, IL-21-, IL-22-, TNF-α-, NOS2-, STAT3-producing, and increases in IL-27- and Foxp3-producing, CD8⁺ T cells. Our results further demonstrated that AG126 treatment effectively decreased IL-21, IL-22, IL-1β, TNF-α, NOS2, JAK1, and STAT3, and increased IL-27 and Foxp3 mRNA and protein expression in brain tissues. Our findings suggest that AG126 elicits a neuroprotective response through downregulation of the IL-21/IL-21R and JAK/STAT pathway in BTBR mice, which could represent a promising novel therapeutic target for ASD treatment.

Resveratrol attenuates pro-inflammatory cytokines and activation of JAK1-STAT3 in BTBR T+ Itpr3tf/J autistic mice

Autism is a neurodevelopmental disorder characterized by qualitative impairment in communication, social interaction, and repetitive stereotypic behavior. Resveratrol plays a role in several disorders such as neuroimmune, autoimmune, and allergic disorders. BTBR T⁺ Itpr3^tf/J (BTBR) mice, a model for autism, show several behavioral deficits that are physiological characteristics similar to those observed in patients with autism. Previous studies have shown that JAK-STAT signaling pathway is associated with many neurodevelopmental disorders. We investigated the possible role of resveratrol on IL-6⁺, TNF-α⁺, IFN-γ⁺, and STAT3⁺ in CD4⁺ T spleen cells in BTBR mice as compared to C57BL/6J mice. We also assessed the effect of resveratrol treatment on IL-6, TNF-α, IFN-γ, JAK1, and STAT3 mRNA expression levels in the brain tissue. We further assessed IL-6, IFN-γ, TNF-α, phosphorylated (p) JAK1, and pSTAT3 (Tyr705) protein expression levels in the brain tissue. Resveratrol (20 and 40 mg/kg)-treated mice had significantly decreased in IL-6⁺, TNF-α⁺, IFN-γ⁺, and STAT3⁺ in CD4⁺ spleen cells as compared with BTBR control mice. Resveratrol treatment also decreased IL-6, TNF-α, IFN-γ, JAK1, and STAT3 mRNA expression levels as compared with BTBR control mice in the brain tissue. Moreover, resveratrol treatment resulted in decreased protein expression levels of IL-6, IFN-γ, TNF-α, pJAK1, and pSTAT3 (Tyr705) as compared with BTBR control mice in the brain tissues. Taken together, these results indicate the efficacy of resveratrol in reducing cytokines and JAK-1/STAT3 signaling in BTBR mice, which is a novel and important finding and might be important for future therapies in neuroimmune dysfunction.

Resveratrol Improves Neuroimmune Dysregulation Through the Inhibition of Neuronal Toll-Like Receptors and COX-2 Signaling in BTBR T+ Itpr3tf/J Mice

Autism is a neurodevelopmental disorder characterized by deficits in qualitative impairments in communication, repetitive and social interaction, restricted, and stereotyped patterns of behavior. Resveratrol has been extensively studied pharmacologically and biologically and has anti-inflammatory, antioxidant, and neuroprotective effects on neuronal damage in neurodegenerative disorders. The BTBR T⁺ Itpr3^tf/J (BTBR) autistic mouse model has been explored for treatment of autism, which shows low reciprocal social interactions, impaired juvenile play, and decreased social approach. Here, we explored whether resveratrol treatment decreases neuroimmune dysregulation mediated through toll-like receptor (TLR4) and nuclear factor-κB (NF-κB) signaling pathway in BTBR mice. We investigated the effect of resveratrol treatment on TLR2, TLR3, TLR4, NF-κB, and inducible nitric oxide synthase (iNOS or NOS2) levels in CD4 spleen cells. We also assessed the effect of resveratrol treatment on TLR2, TLR3, TLR4, NF-κB, iNOS, and cyclooxygenase (COX-2) mRNA expression levels in the brain tissue. We further explored TLR2, TLR4, NF-κB, iNOS, and COX-2 protein expression levels in the brain tissue. Resveratrol treatment on BTBR mice significantly decreased CD4⁺TLR2⁺, CD4⁺TLR3⁺, CD4⁺TLR4⁺ CD4⁺NF-κB⁺, and CD4⁺iNOS⁺ levels in spleen cells. Resveratrol treatment on BTBR mice decreased TLR2, TLR3, TLR4, NF-κB, iNOS, and COX-2 mRNA expression levels in brain tissue. Moreover, resveratrol treatment resulted in decreased protein expression of TLR2, TLR3, TLR4, NF-κB, iNOS, and COX-2 in brain tissue. Taken together, these results indicate that resveratrol treatment improves neuroimmune dysregulation through the inhibition of proinflammatory mediators and TLRs/NF-κB transcription factor signaling, which might be help devise future therapies for neuroimmune disorders.

Imbalance between the anti- and pro-inflammatory milieu in blood leukocytes of autistic children

Accumulating evidence suggests an association between immune dysfunction and autism disorders in a significant subset of children. In addition, an imbalance between pro- and anti-inflammatory pathways has been proposed to play an important role in the pathogenesis of several neurodevelopmental disorders including autism; however, the role of anti-inflammatory molecules IL-27 and CTLA-4 and pro-inflammatory cytokines IL-21 and IL-22 has not previously been explored in autistic children. In the current study, we investigated the expression of IL-21, IL-22, IL-27, and CD152 (CTLA-4) following an in-vitro immunological challenge of peripheral blood mononuclear cells (PBMCs) from children with autism (AU) or typically-developing children (TD) with phorbol-12-myristate 13-acetate (PMA) and ionomycin. In our study, cells from children with AU had increased IL-21 and IL-22 and decreased CTLA-4 expression on CD4+ T cells as compared with cells from the TD control. Similarly, AU cells showed decreased IL-27 production by CD14+ cells compared to that of TD control cells. These results were confirmed by real-time PCR and western blot analyses. Our study shows dysregulation of the immune balance in cells from autistic children as depicted by enhanced pro-inflammatory cytokines, 'IL-21/IL-22' and decreased anti-inflammatory molecules, 'IL-27/CTLA-4'. Thus, further study of this immune imbalance in autistic children is warranted in order to facilitate development of biomarkers and therapeutics.