A Decade of Firearm Injuries: Children Caught in the Crossfire.

Introduction: Firearm injuries (FIs) are the leading cause of preventable morbidity and mortality in pediatric patients. In this study, we aim to define evolving trends and avenues for prevention.

Methods: Following institutional review board approval, medical records of patients presenting to our two State-Designated Level 1 Pediatric Trauma Centers for treatment of FIs from 2010 to 2019 were retrospectively reviewed.

TREM2 deficiency reprograms intestinal macrophages and microbiota to enhance anti-PD-1 tumor immunotherapy.

The gut microbiota and tumor-associated macrophages (TAMs) affect tumor responses to anti-programmed cell death protein 1 (PD-1) immune checkpoint blockade. Reprogramming TAM by either blocking or deleting the macrophage receptor triggering receptor on myeloid cells 2 (TREM2) attenuates tumor growth, and lack of functional TREM2 enhances tumor elimination by anti-PD-1. Here, we found that anti-PD-1 treatment combined with TREM2 deficiency in mice induces proinflammatory programs in intestinal macrophages and a concomitant expansion of in the gut microbiota.

Gut-associated lymphoid tissue attrition associates with response to anti-α4β7 therapy in ulcerative colitis.

Vedolizumab (VDZ) is a first-line treatment in ulcerative colitis (UC) that targets the α4β7- mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) axis. To determine the mechanisms of action of VDZ, we examined five distinct cohorts of patients with UC. A decrease in naïve B and T cells in the intestines and gut-homing (β7) plasmablasts in circulation of VDZ-treated patients suggested that VDZ targets gut-associated lymphoid tissue (GALT).

Gut-associated lymphoid tissue attrition associates with response to anti-α4β7 therapy in ulcerative colitis.

Targeting the α4β7-MAdCAM-1 axis with vedolizumab (VDZ) is a front-line therapeutic paradigm in ulcerative colitis (UC). However, mechanism(s) of action (MOA) of VDZ remain relatively undefined. Here, we examined three distinct cohorts of patients with UC (n=83, n=60, and n=21), to determine the effect of VDZ on the mucosal and peripheral immune system.

Lipid absorption and overall intestinal lymphatic transport are impaired following partial small bowel resection in mice.

Short bowel syndrome (SBS) is associated with diminished levels of serum fats caused by unknown mechanisms. We have shown that mesenteric lymphatics remodel to a more primitive state one week after small bowel resection (SBR); therefore, this study focuses on the effect of chronic lymphatic remodeling and magnitude of resection on intestinal lipid uptake and transport. C57BL6 and Prox1 creER-Rosa26TdTomato (lymphatic reporter) mice underwent 50% or 75% proximal SBR or sham operations.

Ileitis-associated tertiary lymphoid organs arise at lymphatic valves and impede mesenteric lymph flow in response to tumor necrosis factor.

Lymphangitis and the formation of tertiary lymphoid organs (TLOs) in the mesentery are features of Crohn's disease. Here, we examined the genesis of these TLOs and their impact on disease progression. Whole-mount and intravital imaging of the ileum and ileum-draining collecting lymphatic vessels (CLVs) draining to mesenteric lymph nodes from TNF mice, a model of ileitis, revealed TLO formation at valves of CLVs.

LYVE1+ macrophages of murine peritoneal mesothelium promote omentum-independent ovarian tumor growth.

Two resident macrophage subsets reside in peritoneal fluid. Macrophages also reside within mesothelial membranes lining the peritoneal cavity, but they remain poorly characterized. Here, we identified two macrophage populations (LYVE1hi MHC IIlo-hi CX3CR1gfplo/- and LYVE1lo/- MHC IIhi CX3CR1gfphi subsets) in the mesenteric and parietal mesothelial linings of the peritoneum.

SATB2 preserves colon stem cell identity and mediates ileum-colon conversion via enhancer remodeling.

Adult stem cells maintain regenerative tissue structure and function by producing tissue-specific progeny, but the factors that preserve their tissue identities are not well understood. The small and large intestines differ markedly in cell composition and function, reflecting their distinct stem cell populations. Here we show that SATB2, a colon-restricted chromatin factor, singularly preserves LGR5 adult colonic stem cell and epithelial identity in mice and humans.

Racial disparities in triage of adolescent patients after bullet injury.

Background: While pediatric trauma centers (PTCs) and adult trauma centers (ATCs) exhibit equivalent trauma mortality, the optimal care environment for traumatically injured adolescents remains controversial. Race has been shown to effect triage within emergency departments (EDs) with people of color receiving lower acuity triage scores. We hypothesized that African-American adolescents were more likely triaged to an ATC than a PTC compared with their White peers.

Enterically derived high-density lipoprotein restrains liver injury through the portal vein.

The biogenesis of high-density lipoprotein (HDL) requires apoA1 and the cholesterol transporter ABCA1. Although the liver generates most of the HDL in the blood, HDL synthesis also occurs in the small intestine. Here, we show that intestine-derived HDL traverses the portal vein in the HDL subspecies form, in complex with lipopolysaccharide (LPS)-binding protein (LBP).

Liver injury after small bowel resection is prevented in obesity-resistant 129S1/SvImJ mice.

Intestinal failure-associated liver disease is a major morbidity associated with short bowel syndrome. We sought to determine if the obesity-resistant mouse strain (129S1/SvImJ) conferred protection from liver injury after small bowel resection (SBR). Using a parenteral nutrition-independent model of resection-associated liver injury, C57BL/6J and 129S1/SvImJ mice underwent a 50% proximal SBR or sham operation.

COVER: A Curriculum in the Management of Soft Tissue Injury and Infection for Junior Surgery Residents.

Background: While wound management is a common task for practicing surgeons, there is a paucity of dedicated education on soft tissue management during residency training.

Objective: The COVER (Causes of soft tissue injury, Obstacles to closure, Vacuums and stitches, Epithelialization, Rationale for wound care) curriculum was developed to engage junior surgery residents in the management of soft tissue injury and infection.

Methods: Junior surgery residents participated in the COVER lab during academic years 2018-2020.

SAVE 2.0: Identifying and strengthening resident leadership skills through simulation based team training.

Background: The "Surgery for Abdomino-thoracic ViolencE (SAVE)" animate lab engages surgical residents in the management of penetrating injuries in a team setting. Senior residents, representing postgraduate year (PGY) 3-5, assume the role of team leader and facilitate the junior residents, PGY1-2, in operative management of simulated penetrating wounds. Residents completed five scenarios with increasing level of difficulty within set time limits.

Anatomy of Gun Violence: Contextualized Curriculum to Train Surgical Residents in Both Technical and Non-Technical Skills in the Management of Gun Violence.

Background: Gun violence (GV) is a complex public health issue, and the management of GV as a disease engages the surgeon in technical and nontechnical skills. The Anatomy of Gun Violence (AGV) curriculum was developed to teach surgical trainees these seemingly disparate skills, training residents to manage the multiple aspects of firearm injury.

Study Design: The AGV curriculum was delivered over 6 weeks in the 2017-2018 and 2018-2019 academic years (AY), and used multiple educational methods including didactic lectures, mock oral examinations, a Bleeding Control training session, a GV survivor's personal story, a Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) training session, and the Surgery for Abdominal-thoracic ViolencE (SAVE) simulation lab.

Small Bowel Resection Increases Paracellular Gut Barrier Permeability via Alterations of Tight Junction Complexes Mediated by Intestinal TLR4.

Background: Short bowel syndrome resulting from small bowel resection (SBR) is associated with significant morbidity and mortality. Many adverse sequelae including steatohepatitis and bacterial overgrowth are thought to be related to increased bacterial translocation, suggesting alterations in gut permeability. We hypothesized that after intestinal resection, the intestinal barrier is altered via toll-like receptor 4 (TLR4) signaling at the intestinal level.

EGFR in enterocytes & endothelium and HIF1α in enterocytes are dispensable for massive small bowel resection induced angiogenesis.

Background: Short bowel syndrome (SBS) results from significant loss of small intestinal length. In response to this loss, adaptation occurs, with Epidermal Growth Factor Receptor (EGFR) being a key driver. Besides enhanced enterocyte proliferation, we have revealed that adaptation is associated with angiogenesis.

Alterations in pancreatic islet cell function in response to small bowel resection.

After 50% proximal small bowel resection (SBR) in mice, we have demonstrated hepatic steatosis, impaired glucose metabolism without insulin resistance, and increased pancreatic islet area. We sought to determine the consequences of SBR on pancreatic β-cell morphology, proliferation, and expression of a key regulatory hormone, glucagon-like peptide-1 (GLP-1). C57BL/6 mice underwent 50% SBR or sham operation.

Effects of high-fat diet on liver injury after small bowel resection.

Background: The optimal regimen for enteral nutritional support in the management of children with short bowel syndrome (SBS) is not well characterized. A high fat, enteral diet is theoretically beneficial due to increased caloric density and enhanced structural adaptation. We therefore sought to determine the long-term effects of a high fat diet (HFD) on liver injury, a common complication of SBS, compared to a standard chow (SC) diet.

SCORE - Leveling the Playing Field for Surgical Training Programs.

Objective: The Surgical Council on Resident Education (SCORE) web portal provides a uniform, comprehensive, competency-based curriculum for general surgery residents. One of SCORE's principal founding goals was to provide equal opportunity for access of educational resources at programs across the United States which reported having a range of resources. We aimed to determine if there was a difference in portal usage by trainees in independent versus university programs, and across geographic areas.

A Stromal Niche Defined by Expression of the Transcription Factor WT1 Mediates Programming and Homeostasis of Cavity-Resident Macrophages.

Tissue-resident macrophages require specific milieus for the maintenance of defining gene-expression programs. Expression of the transcription factor GATA6 is required for the homeostasis, function and localization of peritoneal cavity-resident macrophages. Gata6 expression is maintained in a non-cell autonomous manner and is elicited by the vitamin A metabolite, retinoic acid.

Single-Cell Analysis Reveals Regional Reprogramming During Adaptation to Massive Small Bowel Resection in Mice.

Background & Aims: The small intestine (SI) displays regionality in nutrient and immunological function. Following SI tissue loss (as occurs in short gut syndrome, or SGS), remaining SI must compensate, or "adapt"; the capacity of SI epithelium to reprogram its regional identity has not been described. Here, we apply single-cell resolution analyses to characterize molecular changes underpinning adaptation to SGS.

Lymphatic network remodeling after small bowel resection.

Background: Short gut syndrome (SGS) following massive small bowel resection (SBR) is a major cause of pediatric mortality and morbidity secondary to nutritional deficiencies and the sequelae of chronic total parenteral nutrition use, including liver steatosis. Despite the importance of lymphatic vasculature in fat absorption, lymphatic response after SBR has not been studied. We hypothesize that lymphatic vessel integrity is compromised in SGS, potentially contributing to the development of impaired lipid transport leading to liver steatosis and metabolic disease.

Trauma Technical Skill and Management Exposure for Junior Surgical Residents - The "SAVE Lab 1.0".

Objective: The "Surgery for Abdomino-thoracic ViolencE (SAVE)" animate lab engages surgical residents in the management of complex penetrating injuries. We hypothesized that residents will improve their understanding of the management of trauma patients and will perform skills that they have not previously performed in training.

Design: Pre- and postlab assessments were reviewed from surgical residents participating in the SAVE lab over 2 years (2017-2018).

Hepatocyte and stellate cell deletion of liver fatty acid binding protein reveals distinct roles in fibrogenic injury.

Liver fatty acid binding protein (L-Fabp) modulates lipid trafficking in enterocytes, hepatocytes, and hepatic stellate cells (HSCs). We examined hepatocyte vs. HSC L-Fabp deletion in hepatic metabolic adaptation and fibrotic injury.