Alteration of gut microbiota-associated epitopes in children with autism spectrum disorders.

BACKGROUND: Autism spectrum disorder (ASD) affects 1% of children and has no cure. Gastrointestinal (GI) problems are common in children with ASD, and although gut microbiota is known to play an important role in ASD through the gut-brain axis, the specific mechanism is unknown. Recent evidence suggests that gut microbiota may participate in the pathogenesis of ASD through immune- and inflammation-mediated pathways. Here, we identified potentially immunogenic epitopes derived from gut microbiota in stool samples from ASD children with and without GI problems and typically developing (TD) children. METHODS: Candidate gut microbiota-associated epitopes (MEs) were identified by blast shotgun metagenomic sequencing of fecal samples from 43 ASD children (19 with and 24 without GI involvement) and 31 sex- and age-matched typically developing (TD) children. Potentially immunogenic epitopes were screened against a predictive human Immune Epitope Database. The composition and abundance of candidate MEs were compared between the three groups of children. RESULTS: MEs identified in ASD children with GI problems were significantly more diverse than those in TD children. ME composition could discriminate between the three groups of children. We identified 34 MEs that were significantly more or less abundant in ASD children than TD children, most (29/34) of the differences in MEs were reduced in ASD and associated with abnormal gut IgA level and altered gut microbiota composition, these MEs were limited effected by clinical factors such as age, gender, and GI problems, of which eleven MEs were pathogenic microorganisms peptides with strong T or B cell response, nine MEs showed high homology to peptides from human self proteins associated with autoimmune disease occurrence, eliciting immune attack against hematopoietic stem cells and inhibition antigen binding. We also found that the abundance of five MEs were increased in ASD, including three human self proteins, gap junction alpha-1 (GJA1), paired box protein Pax-3 (PAX3) and eyes absent homolog 1 isoform 4 (EYA1) which associated with cancer, and a ME with homology to a Listeriolysin O peptide from the pathogenic bacterium Listeria monocytogenes was significantly increased in ASD children compared with TD children. CONCLUSIONS: Our findings demonstrate the abnormal of MEs composition in the gut of children with ASD, moreover, the abnormality in MEs composition was associated with abnormal gut IgA levels and altered gut microbiota composition, this abnormality also suggests that there may be abnormalities in intestinal immunity in children with ASD; In all, thirty-four MEs identified were potential biomarker of ASD, and alterations in MEs may contribute to abnormalities in gut immunity and/or homeostasis in ASD children. Further study of the MEs identified here may advance our understanding of the pathogenesis of ASD.

Expression of PAX3 Distinguishes Biphenotypic Sinonasal Sarcoma From Histologic Mimics.

Biphenotypic sinonasal sarcoma (BSNS) is a distinctive, anatomically restricted, low-grade spindle cell sarcoma that shows considerable histologic overlap with other cellular spindle cell neoplasms. This tumor type shows both myogenic and neural differentiation, which can be demonstrated by immunohistochemistry; however, the available diagnostic markers are relatively nonspecific. BSNS is characterized by PAX3 rearrangements, with MAML3 as the most common fusion partner. Our aim was to determine whether immunohistochemistry using a monoclonal PAX3 antibody could distinguish BSNS from potential histologic mimics, as well as to evaluate a widely available polyclonal PAX8 antibody, which is known to cross-react with other paired box transcription factor family members. Immunohistochemistry for PAX3 and PAX8 was performed on whole sections of 15 BSNS (10 with confirmed PAX3 rearrangement) and 10 cases each of the following histologic mimics: malignant peripheral nerve sheath tumor, monophasic synovial sarcoma, spindle cell rhabdomyosarcoma (RMS), solitary fibrous tumor, sinonasal hemangiopericytoma, and cellular schwannoma, as well as alveolar RMS (which harbors PAX3 or PAX7 gene rearrangements). BSNS showed consistent expression of PAX3 (15/15), all multifocal-to-diffuse and most with moderate-to-strong intensity of staining. One single case of spindle cell RMS showed PAX3 expression (1/10), and all other histologic mimics were completely PAX3-negative. In contrast, nuclear staining for PAX8 was present in all 15 BSNS, 7/10 malignant peripheral nerve sheath tumor, 3/10 cellular schwannomas, 2/10 sinonasal hemangiopericytomas, 1/10 synovial sarcoma, 1 spindle cell RMS, and 1 solitary fibrous tumor. All cases of alveolar RMS were positive for PAX8, and most were also positive for PAX3 (8/10). Immunohistochemical expression of PAX3 is highly sensitive (100%) and specific (98%) for BSNS. A polyclonal PAX8 antibody also stains BSNS (likely due to cross-reactivity with PAX3) but has much lower specificity (75%), with frequent expression in numerous mimics.