Joshua B. Wechsler

Objective: Activated T cell pediatric acute liver failure (TC‐PALF) is characterized by CD8+T cells in liver and peripheral blood. TC‐PALF patients are at increased risk of developing aplastic anemia (AA), an immune‐mediated disorder in which CD8+ T cells target hematopoietic stem and progenitor cells. Clonal expansion of T cell receptors (TCRs) and specific human leukocyte antigen (HLA) class I risk alleles have been reported in AA. We hypothesized TC‐PALF shares similar HLA associations and exhibits increased TCR clonality. Methods: Thirty‐one TC‐PALF and 15 other PALF diagnosis (other‐PALF) patients enrolled in the Pediatric Acute Liver Failure Study Group (PALFSG) were included. Liver tissue DNA underwent TCR β‐chain (TCRβ) complementarity‐determining region 3 sequencing and HLA genotyping. HLA allele frequencies were compared with ethnicity‐matched controls. TCR clonality was assessed and Grouping of Lymphocyte Interactions by Paratope Hotspots 2 (GLIPH2) was used to identify antigen‐convergent, disease‐associated TCR groups. Results: HLA class I alleles HLA‐A*23:01, HLA‐B*35:03, HLA‐B*52:01, and HLA‐B*39:05 were significantly overrepresented among TC‐PALF patients compared to ethnicity‐matched controls. Hepatic TCRβ clonality was increased in the TC‐PALF group. GLIPH2 identified 158 statistically significant TCR convergence groups enriched in TC‐PALF with significant HLA associations, representing putative antigen‐specific TCR clusters. Conclusions: Enrichment of specific HLA class I alleles, increased hepatic TCR clonality, and HLA‐associated TCR convergence groups support an HLA‐restricted, antigen‐driven CD8+ T cell response as a central mechanism of TC‐PALF. These findings provide a mechanistic framework for antigen discovery and future development of immunogenetic biomarkers to improve disease classification, risk stratification, and targeted immunomodulatory therapy.

Background & Aims: Pyloric dysfunction contributes to chronic nausea, vomiting, and abdominal pain in adults and children. The Functional Luminal Imaging Probe (FLIP) has been used in adults to characterize pyloric distensibility as a marker of muscular hypertonicity and to predict symptomatic improvement to intrapyloric botulinum toxin injection (IPBI). FLIP parameters that identify pyloric dysfunction in children are unknown. In this retrospective cohort study, we aimed to characterize the relationship of pyloric FLIP parameters to clinical symptoms, gastric emptying (GE), and antroduodenal manometry (ADM) findings in pediatric patients. Secondarily, we aimed to assess FLIP metrics as related to the subjective response to IPBI. Methods: Chart review was performed for patients undergoing pyloric FLIP for refractory upper gastrointestinal symptoms at Lurie Children's Hospital. FLIP parameters were compared to symptoms, demographics, medical history, GE, ADM findings, and documented response to IPBI. The presence of a distensibility plateau (DP) was assessed. Results: Ninety‐nine patients underwent pyloric FLIP and 74 were treated with IPBI. Pyloric distensibility index (pDI) correlated with age and biological gender. Patients with chronic nausea, early satiety, concurrent pain disorders, joint hypermobility, and orthostatic intolerance demonstrated higher pDI compared to other symptoms. While pDI did not correlate with GE, it was lower in patients with normal fasting patterns on ADM and higher in IPBI responders. Nearly half of patients demonstrated a DP for which pDI was significantly higher in IPBI responders. Conclusions: This pilot study supports pyloric dysfunction as a mechanism underlying chronic upper gastrointestinal symptoms and would support prospective investigation of pyloric FLIP metrics in pediatrics.

Background & Aims: Unchecked inflammation in Eosinophilic esophagitis (EoE) leads to esophageal fibrosis and eventual stricture. Differentiated fibroblasts, termed myofibroblasts, are the main effector cells in fibrosis, responsible for secreting extracellular matrix proteins leading to tissue stiffness. Regulating myofibroblasts has not been explored as a therapeutic possibility in the fibrostenotic esophagus. Herein, we aim to investigate the efficacy of Prostaglandin E₂ (PGE₂) in dedifferentiation of the EoE myofibroblast. Methods: We evaluated the efficacy and mechanism of myofibroblast dedifferentiation using fetal esophageal fibroblasts (FEF3), patient-derived fibroblasts, and a murine model of EoE. Results: Fibrosis markers (αSMA, FN1, and COL1A1) and contractility of myofibroblasts were significantly decreased by PGE₂ via the cAMP pathway. PGE₂ treatment decreased nuclear accumulation of phospho-Smad2/3-YAP complex and induced phospho-YAP proteasomal degradation. Transcriptome analyses of FEF3 treated with TGFβ or PGE₂ revealed that the Integrin1 pathway, and specifically thrombospondin 1 (THBS-1), was significantly upregulated by TGFβ and downregulated by PGE₂, as supported by pseudo-bulk single-cell RNA-seq of EoE biopsies. THBS-1 was shown to be regulated by PGE₂ via the cAMP/YAP pathway, and its knockdown induced myofibroblasts dedifferentiation. In a murine model of EoE, Butaprost, agonist of the E-prostanoid G protein-coupled receptor 2, treatment significantly reduced the expression of THBS-1, αSMA, and FN1 along with a decrease in YAP nuclear translocation. Additionally, collagen fiber organization in the lamina propria was markedly reduced. Conclusion: PGE₂ promotes dedifferentiation of myofibroblasts in EoE via the cAMP/YAP/ THBS-1 pathway. Our data suggest that PGE₂ is a promising treatment strategy for EoE with stenosis. What You Need to Know: Background and Context: In Eosinophilic esophagitis, unchecked inflammation and tissue stiffness drives fibroblast differentiation and fibrostenosis of the esophagus, yet targeting myofibroblasts as regulators of extracellular matrix deposition in fibrostenotic disease remains clinically unexplored. New Findings: Prostaglandin E₂ promotes dedifferentiation of myofibroblasts in eosinophilic esophagitis via the cAMP/YAP pathway, with Thrombospondin-1 identified as a critical YAP regulated target driving fibrostenosis. Limitations: This study focused on fibroblast-specific mechanisms. The effects of PGE₂ on esophageal epithelial differentiation, barrier function, and immune cell recruitment in EoE remain to be determined. Clinical Research Relevance: This study demonstrates proof-of-concept that pharmacological reversal of established fibrosis is achievable in EoE. PGE2 and its EP₂-selective agonists represent translatable therapeutic targets for fibrostenotic EoE—a patient population that remains treatment-refractory to current immunosuppressive approaches. Basic Research Relevance: The cAMP/YAP/THBS-1 signaling in fibroblasts emerges as a critical therapeutic target for esophageal fibrosis. Importantly, this work demonstrates that terminally differentiated myofibroblasts retain remarkable plasticity and can dedifferentiate—challenging the paradigm that fibrosis is irreversible.

INTRODUCTION: Functional lumen imaging probe (FLIP) can assess the esophageal contractile response (CR). Anesthetic agents used during endoscopy affect esophageal contractility, however, the time or dose-dependent effect of specific medications on the esophageal CR in children is unknown. METHODS: Charts of patients aged 3–22 years undergoing endoscopy with FLIP for evaluation of dysphagia at 2 tertiary pediatric hospitals were reviewed. Anesthetic dose and timing were collected. FLIP data were exported to Wklytics to generate Panometry plots, and the CR was classified as normal, borderline, spastic, impaired, or absent based on established definitions. Binary logistic regression was performed to assess whether anesthetic administration was associated with absent CR. End-tidal sevoflurane concentration was compared across groups with normal, borderline, and absent/impaired CR. RESULTS: Three hundred-three pediatric patients with a mean (SD) age of 13 years (4), 65% adolescent boys, were included. Totally, 80 (26%) had abnormal esophageal CR, where 16 (5%) were impaired, 63 (21%) were absent, and 1 was spastic. Two hundred twenty-eight (75%) were diagnosed with eosinophilic esophagitis, and 215 (71%) received sevoflurane. The odds ratio for absent CR if sevoflurane was administered was 8.4 ( P < 0.001). Sevoflurane was used significantly more often for both induction and maintenance in patients with abnormal CR compared with normal CR (70% vs 38%, P < 0.001). During the maintenance phase of anesthesia, end-tidal sevoflurane concentration was higher in patients with abnormal CR compared with normal CR independent of propofol infusion, recruitment site, and distensibility. DISCUSSION: The timing and dose of sevoflurane is strongly associated with esophageal CR impairment during FLIP.

INTRODUCTION: Endoscopy, standard-of-care for monitoring eosinophilic esophagitis (EoE), assesses mucosal inflammation. The Esophageal String Test (EST), a minimally invasive swallowed capsule and immunoassays, quantifies EoE inflammation. We determined whether the EST/EoEScore can monitor disease in patients undergoing treatment. METHODS: Thirty-three samples from 14 patients with EoE (7 children, 7 adults) who underwent repeat endoscopies and ESTs were studied. Biopsies were analyzed for peak eosinophil counts; ESTs were analyzed for EoEScores. RESULTS: Eosinophil counts and EoEScores significantly correlated during treatment, distinguishing patients with active EoE from treatment-associated remissions for 93.9% of ESTs performed. DISCUSSION: The EST can be used to longitudinally monitor responses to treatment in EoE.

Elevated numbers of antibody-secreting cells (ASCs) and anti–double-stranded DNA (anti-dsDNA) antibodies are found in nasal polyp (NP) tissue. The presence of anti-dsDNA IgG in tissue prospectively predicts recurrent NP but the characteristics of the source ASCs are unknown. Here, we investigated whether NP B cells expressing the extrafollicular marker EBI2 have increased propensity for autoantibody production and evaluated the molecular characteristics of NP ASCs. NPs showed increased frequencies of anti-dsDNA IgG and total IgG ASCs compared with tonsils, with more pronounced differences among EBI2 ⁺ cells. In NPs, EBI2 ⁺ cells were frequently double negative (IgD ^– CD27 ^– ) and ASCs. Single-cell RNA-Seq analysis of tonsils and NPs revealed substantial differences in B lineage composition, including differences in percentages of ASCs, germinal centers, proliferative cells, and non-ASCs. NPs exhibited higher expression of specific isotypes ( IGHE , IGHA1 , IGHA2 , and IGHG4 ) and mature plasma genes, including SDC1 and XBP1 , than tonsils. Gene Ontology biological processes indicated upregulated NF-κB and downregulated apoptosis pathways in NP ASCs. Together, these data indicate that NP EBI2 ⁺ ASCs secret increased total and anti-dsDNA IgG compared with those from tonsils and had molecular features of mature plasma cell differentiation.

Background: Post‐infectious disorders of gut‐brain interaction (PI‐DGBI) have significant impact on children and adolescents. The effect of COVID‐19 on PI‐DGBI‐associated symptoms in this population, however, is unknown.Methods: We performed electronic medical record searches to identify patients 8–17 years old with a SARS‐CoV2 PCR test at Lurie Children's Hospital between November 2020 and March 2021 (cohort 1) and April–October 2021 (cohort 2). Questionnaires were administered to assess symptoms prior to and 3 months following the test. This included the Pediatric Eosinophilic Esophagitis Symptom Score (PEESS), questionnaire of pediatric gastrointestinal symptoms—Rome IV, Nausea Profile (NP), dyspepsia symptom survey (DSS), nausea severity profile (NSP), and Pediatric Quality of Life Inventory (PedsQL). We grouped patients based on the presence of symptoms prior to COVID‐19 test or the test result.Results: One hundred and ninety‐six parent(s) or guardian(s) in cohort 1 and 274 in cohort 2 completed surveys and self‐reported their child's COVID‐19 result. Cohort 1 had increased PEESS and DSS scores, lower PedsQL scores, and increased frequency of abdominal pain disorders among patients with symptoms prior to COVID‐19 testing. Both cohorts had increased NP and NSP scores among patients with symptoms prior to COVID‐19 testing that was highest among patients with a positive COVID‐19 test. Abdominal pain and diarrhea prior to COVID‐19 testing predicted higher NP scores.Conclusions: Among symptomatic COVID‐19 tested children, we found increased severity of nausea‐associated somatic, emotional, and gastrointestinal symptoms in the 3 months following the test that was most increased among patients with a positive COVID‐19 test.

Intraepithelial mast cells (MCs) are increased in eosinophilic esophagitis (EoE) and reduced with elimination of dietary antigens. Single food reintroduction can identify triggers of eosinophilia; however, the extent to which specific foods trigger intraepithelial mastocytosis remains unknown. We hypothesized that specific foods drive different degrees of MC inflammation. We previously reported a prospective pediatric EoE cohort treated with a 4-food elimination diet (4FED) with removal of soy, egg, wheat, and milk. We retrieved unstained slides in which baseline, 4FED, and post-4FED diet reintroduction time points were available. Slides were stained with tryptase, and intraepithelial MCs were counted. Comparisons were made by stratifying patients by eosinophilia, basal cell hyperplasia (BCH), endoscopic abnormalities, and symptoms. Pearson correlation was assessed for MCs with eosinophilic, endoscopic, and BCH severity; symptoms; and a novel mucosal activity score combining endoscopic and histologic structural severity. Slides were available from 37 patients with at least 1 food reintroduced. MCs were significantly reduced with 4FED. Wheat led to increased intraepithelial MCs in the upper esophagus and with food-induced eosinophilia, while milk led to significantly increased MCs in the upper and lower esophagus and was significantly associated with patients with food-triggered eosinophilia, endoscopic abnormalities, BCH, and symptoms. MCs best correlated with the mucosal activity score during milk reintroduction. In children with EoE, MCs are reduced with 4FED. During milk reintroduction, significant increases in MCs were observed with all metrics of inflammation along with moderate correlation with structural mucosal activity that was not seen with other foods. This suggests that milk exerts unique effects either directly or indirectly on MCs in the esophagus in EoE patients.