Highlights Social distancing orders have been justifiably required to slow the spread of the Covid-19 pandemic. Little is known regarding the secondary health consequences of these mandates. There was an increased proportion of physical child abuse injuries at our level I pediatric trauma center during the Covid-19 pandemic. Heightened awareness of this unintended consequence of social distancing can help to protect vulnerable children.

Angiotensin-converting enzyme 2 (ACE2) is a potent negative regulator capable of restraining overactivation of the renin–angiotensin system, which contributes to exuberant inflammation after bacterial infection. However, the mechanism through which ACE2 modulates this inflammatory response is not well understood. Accumulating evidence indicates that infectious insults perturb ACE2 activity, allowing for uncontrolled inflammation. In the current study, we demonstrate that pulmonary ACE2 levels are dynamically varied during bacterial lung infection, and the fluctuation is critical in determining the severity of bacterial pneumonia. Specifically, we found that a pre-existing and persistent deficiency of active ACE2 led to excessive neutrophil accumulation in mouse lungs subjected to bacterial infection, resulting in a hyperinflammatory response and lung damage. In contrast, pre-existing and persistent increased ACE2 activity reduces neutrophil infiltration and compromises host defense, leading to overwhelming bacterial infection. Further, we found that the interruption of pulmonary ACE2 restitution in the model of bacterial lung infection delays the recovery process from neutrophilic lung inflammation. We observed the beneficial effects of recombinant ACE2 when administered to bacterially infected mouse lungs following an initial inflammatory response. In seeking to elucidate the mechanisms involved, we discovered that ACE2 inhibits neutrophil infiltration and lung inflammation by limiting IL-17 signaling by reducing the activity of the STAT3 pathway. The results suggest that the alteration of active ACE2 is not only a consequence of bacterial lung infection but also a critical component of host defense through modulation of the innate immune response to bacterial lung infection by regulating neutrophil influx.

Objective: Necrotizing enterocolitis (NEC) develops through exaggerated toll-like receptor 4 (TLR4) signaling in the intestinal epithelium. Breast milk is rich in non-digestible oligosaccharides and prevents NEC through unclear mechanisms. We now hypothesize that the human milk oligosaccharides 2’-Fucosyllactose (2’-FL) and 6’-Sialyllactose (6’-SL), can reduce NEC through inhibition of TLR4 signaling. Design: NEC was induced in newborn mice and premature piglets and infant formula was supplemented with 2’-FL, 6’-SL or lactose. Intestinal tissue was obtained at surgical resection. HMO inhibition of TLR4 was assessed in IEC-6 enterocytes, mice, human tissue explants, and via in silico modeling. Results: Supplementation of infant formula with either 2’-FL and/or 6’-SL, but not the parent sugar lactose, reduced NEC in mice and piglets via reduced apoptosis, inflammation, weight loss, and histological appearance. Mechanistically, both 2’-FL and 6’-SL, but not lactose, reduced TLR4-mediated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) inflammatory signaling in the mouse and human intestine. Strikingly, in silico modeling revealed 2’-FL and 6’-SL, but not lactose, to dock into the binding pocket of the TLR4-MD2 complex, explaining their ability to inhibit TLR4 signaling. Conclusion: 2’-FL and 6’-SL, but not lactose, prevent NEC in mice and piglet models, and attenuate NEC-inflammation in human ileum, in part through TLR4 inhibition.

Necrotizing enterocolitis is a devastating disease of prematurity characterized by gram-negative bacteria colonization and enterocyte death. We identify a role of Toll-like receptor 4-mediated necroptosis of the intestinal epithelium as a precursor to necrotizing enterocolitis development. BACKGROUND & AIMS: Necrotizing enterocolitis (NEC) is a devastating disease of premature infants characterized by Toll-like receptor 4 (TLR4)-dependent intestinal inflammation and enterocyte death. Given that necroptosis is a proinflammatory cell death process that is linked to bacterial signaling, we investigated its potential role in NEC, and the mechanisms involved. METHODS: Human and mouse NEC intestine were analyzed for necroptosis gene expression (ie, RIPK1, RIPK3, and MLKL), and protein activation (phosphorylated RIPK3). To evaluate a potential role for necroptosis in NEC, the effects of genetic (ie, Ripk3 knockout or Mlkl knockout) or pharmacologic (ie, Nec1s) inhibition of intestinal inflammation were assessed in a mouse NEC model, and a possible upstream role of TLR4 was assessed in Tlr4-deficient mice. The NEC-protective effects of human breast milk and its constituent milk oligosaccharides on necroptosis were assessed in a NEC-in-a-dish model, in which mouse intestinal organoids were cultured as either undifferentiated or differentiated epithelium in the presence of NEC bacteria and hypoxia. RESULTS: Necroptosis was activated in the intestines of human and mouse NEC in a TLR4-dependent manner, and was upregulated specifically in differentiated epithelium of the immature ileum. Inhibition of necroptosis genetically and pharmacologically reduced intestinal-epithelial cell death and mucosal inflammation in experimental NEC, and ex vivo in the NEC-in-a-dish system. Strikingly, the addition of human breast milk, or the human milk oligosaccharide 2 fucosyllactose in the ex vivo system, reduced necroptosis and inflammation. CONCLUSIONS: Necroptosis is activated in the intestinal epithelium upon TLR4 signaling and is required for NEC development, and explains in part the protective effects of breast milk.

BackgroundThe COVID-19 pandemic has had far-reaching effects on healthcare systems and society with resultant impact on trauma systems worldwide. This study evaluates the impact the pandemic has had in the Washington, DC Metropolitan Region as compared with similar months in 2019.DesignA retrospective multicenter study of all adult trauma centers in the Washington, DC region was conducted using trauma registry data between January 1, 2019 and May 31, 2020. March 1, 2020 through May 31, 2020 was defined as COVID-19, and January 1, 2019 through February 28, 2020 was defined as pre-COVID-19. Variables examined include number of trauma contacts, trauma admissions, mechanism of injury, Injury Severity Score, trauma center location (urban vs. suburban), and patient demographics.ResultsThere was a 22.4% decrease in the overall incidence of trauma during COVID-19 compared with a 3.4% increase in trauma during pre-COVID-19. Blunt mechanism of injury decreased significantly during COVID-19 (77.4% vs. 84.9%, p<0.001). There was no change in the specific mechanisms of fall from standing, blunt assault, and motor vehicle crash. The proportion of trauma evaluations for penetrating trauma increased significantly during COVID-19 (22.6% vs. 15.1%, p<0.001). Firearm-related and stabbing injury mechanisms both increased significantly during COVID-19 (11.8% vs. 6.8%, p<0.001; 9.2%, 6.9%, p=0.002, respectively).Conclusions and relevanceThe overall incidence of trauma has decreased since the arrival of COVID-19. However, there has been a significant rise in penetrating trauma. Preparation for future pandemic response should include planning for an increase in trauma center resource utilization from penetrating trauma.Level of evidenceEpidemiological, level III.

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Necrotizing enterocolitis (NEC) is a disease of premature infants characterized by acute intestinal necrosis. Current dogma suggests that NEC develops in response to post-natal dietary and bacterial factors, and so a potential role for in utero factors in NEC remains unexplored. We now show that during pregnancy, administration of a diet rich in the aryl hydrocarbon receptor (AHR) ligand indole-3-carbinole (I3C), or of breast milk, activates AHR and prevents NEC in newborn mice by reducing Toll-like receptor 4 (TLR4) signaling in the newborn gut. Protection from NEC requires activation of AHR in the intestinal epithelium which is reduced in mouse and human NEC, and is independent of leukocyte activation. Finally, we identify an AHR ligand (“A18”) that limits TLR4 signaling in mouse and human intestine, and prevents NEC in mice when administered during pregnancy. In summary, AHR signaling is critical in NEC development, and maternally-delivered, AHR-based therapies may alleviate NEC.

Resuscitation task completion varies by team size, with a nonlinear association between number of team members and completed tasks. Management of team size during high-acuity activations, those without prior notification, and those in which the patient has a penetrating injury may help optimize performance.