IV Immunoglobulin Is Associated With Epigenetic, Ribosomal, and Immune Changes in Pediatric Acute-Onset Neuropsychiatric Syndrome

Abstract

Objectives: Pediatric acute-onset neuropsychiatric syndrome (PANS) is characterized by infection-provoked abrupt-onset obsessive compulsive disorder (OCD) and neurodevelopmental regression. Owing to the neuroimmune hypothesis, we investigated the effects of IV immunoglobulin (IVIg) on cell-specific gene expression.

Methods: Single-cell RNA sequencing of peripheral immune cells was performed in 5 children with PANS (median age 8 (5.5-16) years), before and after administering open-label IVIg, compared with 4 controls (median age 13.5 [IQR 12-15] years).

Results: The index PANS event (age 1.8-13 years) involved abrupt eating restriction (n = 5), developmental regression (n = 4), and OCD (n = 3). A total of 144,470 cells were sequenced and clustered into 11 cell types. Children with PANS before IVIg compared with controls showed downregulated immune pathways (defense response, innate immunity, secretory granules) in most cell types, with natural killer (NK) cells showing upregulated immune pathways (response to corticosteroid), supporting baseline "immune dysregulation." Ribosomal pathways were upregulated in neutrophils and CD8 T cells but downregulated in NK cells. In children with PANS after IVIg, the baseline immune and ribosomal pathway abnormalities were reversed and histone modification pathways (histone methyltransferase, chromatin) were downregulated in neutrophils and NK cells.

Discussion: We propose that PANS is an epigenetic immune brain disorder with cellular epigenetic, ribosomal, and immune dysregulation. Epigenetic and immune-modulating therapies, such as IVIg, may have disease-modifying effects.

Figure 1. Single-Cell RNA Sequencing in Children With PANS Before and After IVIg: UMAP, DEGs, Neutrophil Pathways

(A) Uniform manifold approximation and projection (UMAP) analysis identified 11 distinct cell clusters. (B) Bar chart of differentially expressed genes (DEGs) across 7 cell types in children with pediatric acute neuropsychiatric syndrome (PANS) showing the number of upregulated (red) or downregulated (blue) DEGs. In children with PANS pre-IVIg vs controls (left), differentially expressed genes (DEGs) with FDR <0.05 of the 7 cell types ranged from 49 to 947 genes per cell type. In children with PANS post-IVIg vs pre-IVIg (right), there were 109–2,347 DEGs per cell type. (C) Bar plot of the top 5 upregulated and downregulated GSEA GO pathways in neutrophils from children with pre-IVIg PANS vs controls (left) and children with PANS post-IVIg vs pre-IVIg (right). (D) Connectivity network enrichment plot (CNET) of the upregulated “response to bacterium” GO pathway (left) and downregulated “histone modification” GO pathway (right) in neutrophils from children with PANS post-IVIg vs pre-IVIg. Dot size corresponds to the number of genes enriching that pathway.

Figure 2. Single-Cell RNA Sequencing in Children With PANS Before and After IVIg: NK Cell Pathways, Dotplot Across Cell Types

(A) Bar plot of top 5 upregulated and downregulated GSEA GO pathways in NK cells from children with pre-IVIg pediatric acute neuropsychiatric syndrome (PANS) vs controls (left) and children with PANS post-IVIg vs pre-IVIg (right). (B) Connectivity network enrichment plot of the upregulated “cytosolic ribosome” GO pathway (left) and downregulated “histone methyltransferase” GO pathway (right) in NK cells from children with PANS post-IVIg vs pre-IVIg. Dot size corresponds to the number of genes enriching that pathway. (C) Heatmap of genes in “histone methyltransferase” GO pathway by average log2 fold change, with pre-IVIg vs control (left) and post-IVIg vs pre-IVIg comparison (right). (D) Dot plot visualizing the top 5 upregulated and downregulated GSEA GO pathways across cell types in children with PANS pre-IVIg vs controls (left) and children with PANS post-IVIg vs pre-IVIg (right). Significant pathways (FDR <0.05) were simplified, and only those that were present in >3 cell types in PANS pre-IVIg vs control comparison were plotted. Dot size represents the -log10(padj) of the pathway while the color intensity represents the normalized enrichment score (NES).