Postoperative Respiratory Complications in SARS-CoV-2 Positive Pediatric Patients Across 20 United States Hospitals: A Cohort Study.

INTRODUCTION: Data examining rates of postoperative complications among SARS-CoV-2 positive children are limited. The purpose of this study was to evaluate the impact of symptomatic and asymptomatic SARS-CoV-2 positive status on postoperative respiratory outcomes for children. METHODS: This retrospective cohort study included SARS-CoV-2 positive pediatric patients across 20 hospitals who underwent general anesthesia from March to October 2020. The primary outcome was frequency of postoperative respiratory complications, including: high-flow nasal cannula/non invasive ventilation, reintubation, pneumonia, Extracorporeal Membrane Oxygenation (ECMO), and 30-day respiratory-related readmissions or emergency department (ED) visits. Univariate analyses were used to evaluate associations between patient and procedure characteristics and stratified analyses by symptoms were performed examining incidence of complications. RESULTS: Of 266 SARS-CoV-2 positive patients, 163 (61.7%) were male, and the median age was 10 years (interquartile range 4-14). The majority of procedures were emergent or urgent (n = 214, 80.5%). The most common procedures were appendectomies (n = 78, 29.3%) and fracture repairs (n = 40,15.0%). 13 patients (4.9%) had preoperative symptoms including cough or dyspnea. 26 patients (9.8%) had postoperative respiratory complications, including 15 requiring high-flow oxygen, 8 with pneumonia, 4 requiring non invasive ventilation, 3 respiratory ED visits, and 2 respiratory readmissions. Respiratory complications were more common among symptomatic patients than asymptomatic patients (30.8% vs. 8.7%, p = 0.01). Higher ASA class and comorbidities were also associated with postoperative respiratory complications. CONCLUSIONS: Postoperative respiratory complications are less common in asymptomatic versus symptomatic SARS-COV-2 positive children. Relaxation of COVID-19-related restrictions for time-sensitive, non urgent procedures in selected asymptomatic patients may be reasonably considered. Additionally, further research is needed to evaluate the costs and benefits of routine testing for asymptomatic patients. LEVEL OF EVIDENCE: Iii, Respiratory complications.

Differential Contribution of Pancreatic Fibroblast Subsets to the Pancreatic Cancer Stroma.

BACKGROUND & AIMS: Although the healthy pancreas consists mostly of epithelial cells, pancreatic cancer and the precursor lesions known as pancreatic intraepithelial neoplasia, are characterized by an extensive accumulation of fibroinflammatory stroma that includes a substantial and heterogeneous fibroblast population. The cellular origin of fibroblasts within the stroma has not been determined. Here, we show that the Gli1 and Hoxb6 markers label distinct fibroblast populations in the healthy mouse pancreas. We then set out to determine whether these distinct fibroblast populations expanded during carcinogenesis. METHODS: We developed genetically engineered models using a dual-recombinase approach that allowed us to induce pancreatic cancer formation through codon-optimized Flp recombinase-driven epithelial recombination of Kirsten rat sarcoma viral oncogene homolog while labeling Gli1+ or Hoxb6+ fibroblasts in an inducible manner. By using these models, we lineage-traced these 2 fibroblast populations during the process of carcinogenesis. RESULTS: Although in the healthy pancreas Gli1+ fibroblasts and Hoxb6+ fibroblasts are present in similar numbers, they contribute differently to the stroma in carcinogenesis. Namely, Gli1+ fibroblasts expand dramatically, whereas Hoxb6+ cells do not. CONCLUSIONS: Fibroblasts present in the healthy pancreas expand during carcinogenesis, but with a different prevalence for different subtypes. Here, we compared Gli1+ and Hoxb6+ fibroblasts and found only Gli1+ expanded to contribute to the stroma during pancreatic carcinogenesis.

Prominin-1 Promotes Biliary Fibrosis Associated With Biliary Atresia.

In patients with biliary atresia (BA), the extent of intrahepatic biliary fibrosis negatively correlates with successful surgical bypass of the congenital cholangiopathy as well as subsequent transplant-free survival. We recently linked the expansion of a population of prominin-1 (Prom1)-expressing hepatic progenitor cells to biliary fibrogenesis. Herein, we hypothesized that Prom1-expressing progenitor cells play a role in BA-associated fibrosis. Rhesus rotavirus (RRV)-mediated experimental BA was induced in newborn mice homozygous for the transgene Prom1cre-ert2-nlacz , which was knocked in to the Prom1 gene locus, thus creating functional Prom1 knockout (KO) mice, and their wildtype (WT) littermates. Clinical data and tissue samples from BA infants from the Childhood Liver Disease Research Consortium were analyzed. Extrahepatic biliary obliteration was present in both WT and KO mice; there was no difference in serum total bilirubin (TBili) levels. The intrahepatic periportal expansion of the PROM1pos cell population, typically observed in RRV-induced BA, was absent in KO mice. RRV-treated KO mice demonstrated significantly fewer cytokeratin-19 (CK19)-positive ductular reactions (P = 0.0004) and significantly less periportal collagen deposition (P = 0.0001) compared with WT. RRV-treated KO mice expressed significantly less integrin-ß6, which encodes a key biliary-specific subunit of a transforming growth factor (TGF) ß activator (P = 0.0004). Infants with successful biliary drainage (Tbili ≤1.5 mg/dL within 3 months postoperatively), which is highly predictive of increased transplant-free survival, expressed significantly less hepatic PROM1, CK19, and COLLAGEN-1α compared with those with TBili >1.5 (P < 0.05). Conclusion: Prom1 plays an important role in biliary fibrogenesis, in part through integrin-mediated TGF pathway activation.

Epithelial-Myeloid cell crosstalk regulates acinar cell plasticity and pancreatic remodeling in mice.

Dedifferentiation of acini to duct-like cells occurs during the physiologic damage response in the pancreas, but this process can be co-opted by oncogenic Kras to drive carcinogenesis. Myeloid cells infiltrate the pancreas during the onset of pancreatic cancer, and promote carcinogenesis. Here, we show that the function of infiltrating myeloid cells is regulated by oncogenic Kras expressed in epithelial cells. In the presence of oncogenic Kras, myeloid cells promote acinar dedifferentiation and carcinogenesis. Upon inactivation of oncogenic Kras, myeloid cells promote re-differentiation of acinar cells, remodeling of the fibrotic stroma and tissue repair. Intriguingly, both aspects of myeloid cell activity depend, at least in part, on activation of EGFR/MAPK signaling, with different subsets of ligands and receptors in different target cells promoting carcinogenesis or repair, respectively. Thus, the cross-talk between epithelial cells and infiltrating myeloid cells determines the balance between tissue repair and carcinogenesis in the pancreas.