Objectives:In many pediatric acute liver failure (PALF) cases, a diagnosis is not identified, and the etiology is indeterminate (IND-PALF). Our pilot study found dense CD8 T-cell infiltrates and increased T-cell clonality in liver specimens from IND-PALF patients. We aimed to validate these findings in a multicenter cohort with investigators blinded to diagnosis.Methods:PALF Study Group registry subjects with IND-PALF (n = 37) and known diagnoses (DX-PALF) (n = 18), ages 1 to 17 years, with archived liver tissue were included. Liver tissue slides were stained for T cells (CD8 and CD4), B cells (CD20), macrophages (CD163), perforin, and tissue resident-memory T cells (Trm, CD103), and scored as minimal, moderate, or dense. Lymphocytes were isolated from frozen liver tissue for T-cell receptor beta (TCRβ) sequencing.Results:Dense hepatic CD8 staining was found in significantly more IND-PALF (n = 29, 78%) compared with DX-PALF subjects (n = 5, 28%) (P = 0.001). IND-PALF subjects were more likely to have dense or moderate perforin (88% vs 50%,P = 0.03) and CD103 (82% vs 40%,P = 0.02) staining compared with DX-PALF subjects. TCRβ sequencing of 15 IND-PALF cases demonstrated increased clonal overlap compared with 6 DX-PALF cases (P = 0.002).Conclusions:Dense infiltration of effector Trm CD8 T cells characterizes liver tissue from IND-PALF subjects. Increased clonality suggests the T-cell expansion is antigen(s)-driven as opposed to a nonspecific inflammatory response. These findings support CD8 staining as a new biomarker of the activated CD8 T-cell PALF phenotype. Future studies are needed to characterize potential antigens, host risk factors, and inflammatory pathways with the goal of developing targeted therapies.

Background & aims Limited understanding of the role for specific macrophage subsets in the pathogenesis of cholestatic liver injury is a barrier to advancing medical therapy. Macrophages have previously been implicated in both the mal-adaptive and protective responses in obstructive cholestasis. Recently two macrophage subsets were identified in non-diseased human liver; however, no studies to date fully define the heterogeneous macrophage subsets during the pathogenesis of cholestasis. Here, we aim to further characterize the transcriptional profile of macrophages in pediatric cholestatic liver disease. Methods We isolated live hepatic immune cells from patients with biliary atresia (BA), Alagille syndrome (ALGS), and non-cholestatic pediatric liver by fluorescence activated cell sorting. Through single-cell RNA sequencing analysis and immunofluorescence, we characterized cholestatic macrophages. We next compared the transcriptional profile of pediatric cholestatic and non-cholestatic macrophage populations to previously published data on normal adult hepatic macrophages. Results We identified 3 distinct macrophage populations across cholestatic liver samples and annotated them as lipid-associated macrophages, monocyte-like macrophages, and adaptive macrophages based on their transcriptional profile. Immunofluorescence of liver tissue using markers for each subset confirmed their presence across BA (n = 6) and ALGS (n = 6) patients. Cholestatic macrophages demonstrated reduced expression of immune regulatory genes as compared to normal hepatic macrophages and were distinct from macrophage populations defined in either healthy adult or pediatric non-cholestatic liver. Conclusions We are the first to perform single-cell RNA sequencing on human pediatric cholestatic liver and identified three macrophage subsets with distinct transcriptional signatures from healthy liver macrophages. Further analyses will identify similarities and differences in these macrophage sub-populations across etiologies of cholestatic liver disease. Taken together, these findings may allow for future development of targeted therapeutic strategies to reprogram macrophages to an immune regulatory phenotype and reduce cholestatic liver injury.

ABSTRACTα-Catenins are actin-filament binding proteins and critical subunits of the cadherin-catenin cell-cell adhesive complex. They are found in nominally-defined epithelial (E), neural (N), and testis (T) forms transcribed from three distinct genes. While most of α-catenin research has focused on the developmentally essential founding member, αE-catenin, this review discusses recent studies on αT-catenin (CTNNA3), a developmentally dispensable isoform that is emerging as relevant to cardiac, allergic and neurological diseases.

In two independent microarray studies involving primary airway epithelial cells, the relative gene expression of TMEM178 decreases with the progression of asthma severity. Our manuscript creates a paradigm for future studies dissecting the role of Tmem178 in the pathogenesis of severe asthma.

Introduction: Previously, we discovered similar esophageal gene expression patterns in patients with systemic sclerosis and eosinophilic esophagitis where eosinophil/mast cell–targeted therapies are beneficial. Because systemic sclerosis and eosinophilic esophagitis patients experience similar esophageal symptoms, we hypothesized that eosinophil/mast cell–directed therapy may potentially benefit systemic sclerosis patients. Herein, we determine the association between esophageal mast cell quantities, gene expression, and clinical parameters in order to identify systemic sclerosis patients who may benefit from eosinophil/mast cell–directed therapy. Methods: Esophageal biopsies from systemic sclerosis patients and healthy participants were stained for tryptase, a mast cell marker, and associations with relevant clinical parameters including 24-h esophageal pH testing were assessed. Intra-epithelial mast cell density was quantified by semi-automated microscopy. Microarray data were utilized for functional and gene set enrichment analyses and to identify intrinsic subset assignment, a systemic sclerosis molecular classification system that includes inflammatory, proliferative, limited, and normal-like subsets. Results: Esophageal biopsies from 40 systemic sclerosis patients (39 receiving proton pump inhibition) and eleven healthy participants were studied. Mast cell numbers in both the upper esophagus ( rs = 0.638, p = 0.004) and the entire (upper + lower) esophagus ( rs = 0.562, p = 0.019) significantly correlated with acid exposure time percentage. The inflammatory, fibroproliferative, and normal-like intrinsic subset originally defined in skin biopsies were identified in esophageal biopsies. Although esophageal mast cell numbers in systemic sclerosis patients and healthy participants were similar, gene expression for mast cell–related pathways showed significant upregulation in the inflammatory intrinsic subset of systemic sclerosis patients compared to patients classified as proliferative or normal-like. Discussion: Esophageal mast cell numbers are heterogeneous in systemic sclerosis patients and may correlate with acid exposure. Patients with inflammatory intrinsic subset profiles in the esophagus demonstrate more tryptase staining. Mast cell–targeted therapy may be a useful therapeutic approach in systemic sclerosis patients belonging to the inflammatory intrinsic subset, but additional studies are warranted.