Functional side-to-side splenorenal shunts to treat extrahepatic portal vein thrombosis in children.

BACKGROUND: Surgical shunts are commonly used to manage complications resulting from extrahepatic portal vein thrombosis (EHPVT) in children. We describe a single-center experience utilizing a functional Side-to-Side Splenorenal Shunt (fSRS), created using either an enlarged inferior mesenteric vein (IMV) or left adrenal vein (LAV). METHODS: Pediatric patients with isolated EHPVT who were poor candidates for a Rex shunt and who underwent a fSRS procedure at our institution between 2003 and 2020 were reviewed. The pre/post shunt portosystemic gradient change, rates of early and late complications, postoperative shunt patency, and mortality were evaluated. RESULTS: Twelve EHPVT patients (mean age of 6.1 years) underwent a fSRS procedure. The mean portosystemic gradient change for the cohort was -11.7 mmHg (±4.9). There were no cases of recurrent variceal bleeding or episodes of shunt thrombosis reported after fSRS procedures. CONCLUSIONS: Surgical shunts continue to be an important adjunct in the treatment of complications related to EHPVT. The functional Side-to-Side Splenorenal Shunt is a safe alternative that is easy to perform, involves minimal dissection and requires only a single anastomosis.

Infant T cells are developmentally adapted for robust lung immune responses through enhanced T cell receptor signaling.

Infants require coordinated immune responses to prevent succumbing to multiple infectious challenges during early life, particularly in the respiratory tract. The mechanisms by which infant T cells are functionally adapted for these responses are not well understood. Here, we demonstrated using an in vivo mouse cotransfer model that infant T cells generated greater numbers of lung-homing effector cells in response to influenza infection compared with adult T cells in the same host, due to augmented T cell receptor (TCR)­mediated signaling. Mouse infant T cells showed increased sensitivity to low antigen doses, originating at the interface between T cells and antigen-bearing accessory cells­through actin-mediated mobilization of signaling molecules to the immune synapse. This enhanced signaling was also observed in human infant versus adult T cells. Our findings provide a mechanism for how infants control pathogen load and dissemination, which is important for designing developmentally targeted strategies for promoting immune responses at this vulnerable life stage.

GATA3-Controlled Nucleosome Eviction Drives MYC Enhancer Activity in T-cell Development and Leukemia.

Long-range enhancers govern the temporal and spatial control of gene expression; however, the mechanisms that regulate enhancer activity during normal and malignant development remain poorly understood. Here, we demonstrate a role for aberrant chromatin accessibility in the regulation of MYC expression in T-cell lymphoblastic leukemia (T-ALL). Central to this process, the NOTCH1-MYC enhancer (N-Me), a long-range T cell-specific MYC enhancer, shows dynamic changes in chromatin accessibility during T-cell specification and maturation and an aberrant high degree of chromatin accessibility in mouse and human T-ALL cells. Mechanistically, we demonstrate that GATA3-driven nucleosome eviction dynamically modulates N-Me enhancer activity and is strictly required for NOTCH1-induced T-ALL initiation and maintenance. These results directly implicate aberrant regulation of chromatin accessibility at oncogenic enhancers as a mechanism of leukemic transformation. SIGNIFICANCE: MYC is a major effector of NOTCH1 oncogenic programs in T-ALL. Here, we show a major role for GATA3-mediated enhancer nucleosome eviction as a driver of MYC expression and leukemic transformation. These results support the role of aberrant chromatin accessibility and consequent oncogenic MYC enhancer activation in NOTCH1-induced T-ALL.This article is highlighted in the In This Issue feature, p. 1631.