The Scalding Truth: Geospatial Analysis Identifies Communities at Risk for Pediatric Scald Burns.

INTRODUCTION: Pediatric scald burns account for 12% of all U.S. burn center admissions and are the most common type of burn in children. We hypothesized that geospatial analysis of burn registry data could identify specific geographic areas and risk factors to focus injury prevention efforts. METHODS: The burn registry of a U.S. regional burn center was used to retrospectively identify pediatric scald burn patients ages 0-17, from January 2018 to June 2023. Geocoding of patient home addresses with census tract data was performed. Area Deprivation Index (ADI) was assigned to patients at the census block group level. Burn incident hot spot analysis to identify statistically significant burn incident clusters was done using the Getis Ord Gi∗ statistic. RESULTS: There were 950 pediatric scald burn patients meeting study criteria. The cohort was 52% male and 36% White, with median age of 3 y and median total body surface area of 1.5%; 23.8% required hospital admission. On multivariable logistic regression, increased child poverty levels (P = 0.004) and children living in single-parent households (P = 0.009) were associated with increased scald burn incidence. Geospatial analysis identified burn hot spots, which were associated with higher ADI (P < 0.001). Black patients were more likely to undergo admission compared to White patients. CONCLUSIONS: Geospatial analysis of burn registry data identified geographic areas at high risk of pediatric scald burn. ADI, poverty, and children in single-parent households were the greatest predictors of injury. Addressing these inequalities requires targeted injury prevention education, enhanced outpatient support systems and more robust community resources.

Identification and management of low-risk isolated traumatic brain injury patients initially treated at a rural level IV trauma center.

STUDY OBJECTIVE: Our goal was to determine if low-risk, isolated mild traumatic brain injury (TBI) patients who were initially treated at a rural emergency department may have been safely managed without transfer to the tertiary referral trauma center. METHODS: This was a retrospective observational analysis of isolated mild TBI patients who were transferred from a rural Level IV Trauma Center to a regional Level I Trauma Center between 2018 and 2022. Patients were risk-stratified according to the modified Brain Injury Guidelines (mBIG). Data abstracted from the electronic medical record included patient presentation, management, and outcomes. RESULTS: 250 patients with isolated mild TBI were transferred out to the Level I Trauma Center. Fall was the most common mechanism of injury (69.2%). 28 patients (11.2%) were categorized as low-risk (mBIG1). No mBIG1 patients suffered a progression of neurological injury, had worsening of intracranial hemorrhage on repeat head CT, or required neurosurgical intervention. 12/28 (42.9%) of mBIG1 patients had a hospital length of stay of 2 days or less, typically for observation. Those with longer lengths of stay were due to medical complications, such as sepsis, or difficulty in arranging disposition. CONCLUSION: We propose that patients who meet mBIG1 criteria may be safely observed without transfer to a referral Level I Trauma Center. This would be of considerable benefit to patients, who would not need to leave their community, and would improve resource utilization in the region.

Post-traumatic Liver Pseudoaneurysms: Rare but Serious Sequela.

INTRODUCTION: The liver is the most commonly injured organ after blunt abdominal trauma. Nonoperative management is the standard of care in stable individuals. Liver injuries, particularly high-grade injuries, can develop pseudoaneurysms (PSAs), which can rupture and cause life-threatening bleeding, even after hospital discharge. There is no consensus on whether patients should receive predischarge contrast computed tomography (CT) screening, or at what time interval after injury, nor which patients are at the highest risk for PSA. The purpose of this study was to identify the rates of PSA in our population and potential risk factors for their formation. METHODS: The trauma registry at our Level 1 urban trauma center was queried for patients admitted with liver injuries between 2015 and 2021. Demographic information was collected from the registry. Individual charts were then reviewed for timing of CT scans, CT findings, interventions, and complications. Liver injury grade was assessed using radiology reports or operative findings. The frequency of PSAs was then analyzed using descriptive statistics using Microsoft Excel and SPSS for odds ratio. RESULTS: A total of 172 patients were admitted with liver injuries during the study period. 130 patients received a CT scan diagnosing liver injury, 42 were diagnosed with liver injury intraoperatively. Of the 130 patients (59.9%) which received follow-up CT scans, six (6.5%) developed PSA, four of which being from penetrating injuries (odds ratio, 6.95). CONCLUSIONS: This study demonstrated a low incidence of PSA consistent with the known literature. We found the majority of the PSA developed following penetrating injury. This may represent a significant indication for follow-up imaging regardless of grade. A larger study will be necessary to identify those most at risk for PSA formation and determine the best PSA screening algorithm.

A majority of trauma-related deep venous thromboses resolve prior to discharge.

Post-traumatic DVTs present unique challenges in patient populations with specific high-risk injury patterns. Duplex ultrasound (US) can be used to assess evolution of DVTs and may guide treatment for high-risk patients. We hypothesized that many DVTs resolve during the initial admission. Weekly duplex US are ordered on all trauma inpatients regardless of prior DVT at our facility. We reviewed US and outcomes data on all patients with lower extremity DVTs at our Level I trauma center from January 2012-December 2021. 392 patients were diagnosed with lower extremity DVT by US. 261 (67%) patients received follow-up US with a mean time to repeat US of 6 days. Of these, 91 (35%) patients experienced DVT resolution prior to the first follow-up US, and 141 (54%) patients experienced resolution prior to discharge. Mean time to resolution was 10 days. Over 50% of DVTs resolve before discharge and are detected by US. Further studies and post-discharge follow-up are needed to determine if patients with resolved DVTs can be managed without therapeutic anticoagulation.

CHRFAM7A expression in mice increases resiliency after injury.

INTRODUCTION: The CHRNA7 gene encodes the α-7 nicotinic acetylcholine receptor (α7nAchR) that regulates anti-inflammatory responses to injury; however, only humans express a variant gene called CHRFAM7A that alters the function of α7nAChR; CHRFAM7A expression predominates in bone marrow and monocytes/macrophages where the CHRFAM7A/CHRNA7 ratio is highly variable between individuals. We have previously shown in transgenic mice that CHRFAM7A increased emergency myelopoiesis from the bone marrow and monocyte/macrophage expression in lungs. MATERIALS AND METHODS: CHRFAM7A transgenic mice are compared to age- and gender-matched wild-type (WT) siblings. We utilized a model of sepsis using LPS injection to measure survival. Lung vascular permeability was measured after severe burn injury in WT vs. CHRFAM7A transgenic mice. Bone marrow CHRFAM7A expression was evaluated using adoptive transfer of CHRFAM7A transgenic bone marrow into WT mice. RESULTS: Here, we demonstrate that CHRFAM7A expression results in an anti-inflammatory phenotype with an improved survival to LPS and decreased acute lung injury in a severe cutaneous burn model compared to WT. CONCLUSIONS: These data suggest that the relative expression of CHRFAM7A may alter resiliency to injury and contribute to individual variability in the human systemic inflammatory response (SIRS) to injury.

Predictors of Readmission Following Treatment for Traumatic Hemothorax.

INTRODUCTION: Retained-hemothorax after trauma can be associated with prolonged hospitalization, empyema, pneumonia, readmission, and the need for additional intervention. The purpose of this study is to reduce patient morbidity associated with retained-hemothorax by defining readmission rates and identifying predictors of readmission after traumatic hemothorax. METHODS: The Nationwide Readmission Database for 2017 was queried for patients with an index admission for traumatic hemothorax during the first 9 mo of the year. Deaths during the index admission were excluded. Data collected includes demographics, injury mechanism, outcomes and interventions including chest tube, video-assisted thoracoscopic surgery, and thoracotomy. Chest-related readmissions (CRR) were defined as hemothorax, pleural effusion, pyothorax, and lung abscess. Univariate and multivariate analysis were used to identify predictors of readmission. RESULTS: There were 13,903 patients admitted during the study period with a mean age of 53 ± 21, 75.2% were admitted after blunt versus 18.3% penetrating injury. The overall 90-day readmission rate was 20.8% (n = 2896). The 90-day CRR rate was 5.7% (n = 794), with 80.5% of these occurring within 30 d. Of all CRR, 62.3% (n = 495) required an intervention (chest tube 72.7%, Thoracotomy 26.9%, video-assisted thoracoscopic surgery 0.4%). Mortality for CRR was 6.2%. Predictors for CRR were age >50, pyothorax or pleural effusion during the index admission and discharge to another healthcare facility or skilled nursing facility. CONCLUSIONS: Majority of CRR after traumatic hemothorax occur within 30 d of discharge and frequently require invasive intervention. These findings can be used to improve post discharge follow-up and monitoring.

Uniquely human CHRFAM7A gene increases the hematopoietic stem cell reservoir in mice and amplifies their inflammatory response.

A subset of genes in the human genome are uniquely human and not found in other species. One example is CHRFAM7A, a dominant-negative inhibitor of the antiinflammatory α7 nicotinic acetylcholine receptor (α7nAChR/CHRNA7) that is also a neurotransmitter receptor linked to cognitive function, mental health, and neurodegenerative disease. Here we show that CHRFAM7A blocks ligand binding to both mouse and human α7nAChR, and hypothesized that CHRFAM7A-transgenic mice would allow us to study its biological significance in a tractable animal model of human inflammatory disease, namely SIRS, the systemic inflammatory response syndrome that accompanies severe injury and sepsis. We found that CHRFAM7A increased the hematopoietic stem cell (HSC) reservoir in bone marrow and biased HSC differentiation to the monocyte lineage in vitro. We also observed that while the HSC reservoir was depleted in SIRS, HSCs were spared in CHRFAM7A-transgenic mice and that these mice also had increased immune cell mobilization, myeloid cell differentiation, and a shift to inflammatory monocytes from granulocytes in their inflamed lungs. Together, the findings point to a pathophysiological inflammatory consequence to the emergence of CHRFAM7A in the human genome. To this end, it is interesting to speculate that human genes like CHRFAM7A can account for discrepancies between the effectiveness of drugs like α7nAChR agonists in animal models and human clinical trials for inflammatory and neurodegenerative disease. The findings also support the hypothesis that uniquely human genes may be contributing to underrecognized human-specific differences in resiliency/susceptibility to complications of injury, infection, and inflammation, not to mention the onset of neurodegenerative disease.

Emergency General Surgery and the Gallbladder: The Affordable Care Act's Impact on Practice Patterns.

BACKGROUND: Gallbladder disease frequently requires emergency general surgery (EGS). The Affordable Care Act (ACA) mandated health insurance coverage for all with the intent to improve access to care and decrease morbidity, mortality, and costs. We hypothesize that after the ACA open-enrollment in 2014 the number of EGS cholecystectomies decreased as access to care improved with a shift in EGS cholecystectomies to teaching institutions. METHODS: A retrospective review of the National Inpatient Sample Database from 2012 to quarter 3 of 2015 was performed. Patients age 18-64, with a nonelective admission for gallbladder disease based on ICD-9 codes, were collected. Outcomes measured included cholecystectomy, complications, mortality, and wage index-adjusted costs. The effect of the ACA was determined by comparing preACA to postACA years. RESULTS: 189,023 patients were identified. In the postACA period the payer distribution for admissions decreased for Self-pay (19.3% to 13.6%, P < 0.001), Medicaid increased (26.3% to 34.0%, P < 0.001) and Private insurance was unchanged (48.6% to 48.7%, P = 0.946). PostACA, admissions to teaching hospitals increased across all payer types, EGS cholecystectomies decreased, while complications increased, and mortality was unchanged. Median costs increased significantly for Medicaid and Private insurance while Self-pay was unchanged. Based on adjusted DID analyses for Insured compared to Self-pay patients, EGS cholecystectomies decreased (-2.7% versus -1.21%, P = 0.033) and median cost increased more rapidly (+$625 versus +$166, P = 0.017). CONCLUSIONS: The ACA has changed EGS, shifting the majority of patients to teaching institutions despite insurance type and decreasing the need for EGS cholecystectomy. The trend toward higher complication rate with increased overall cost requires attention.

Methamphetamine Use is Associated with Increased Surgical Site Infections after Trauma Laparotomy.

BACKGROUND: Methamphetamine (METH) use causes significant vasoconstriction, which can be severe enough to cause bowel ischemia. Methamphetamines have also been shown to alter the immune response. These effects could predispose METH users to poor wound healing, increased infections, and other post-operative complications. We hypothesized that METH users would have longer length of stay and higher rates of complications compared to non-METH users. METHODS: The trauma registry for our urban Level 1 trauma center was searched for patients that received an exploratory laparotomy from 2016 to 2019. A total 204 patients met criteria and 52 (25.5%) were METH positive. Length of stay (LOS), ventilator days, abbreviated injury scale (AIS), and wound class were compared using nonparametric statistics. Age and injury severity score (ISS) were compared using a Student's t-test. A Chi Square or Fisher's Exact test was used to compare sex, mechanism of injury, and rates of infectious complications. RESULTS: Methamphetamine-positive patients had a significantly higher rate of surgical site infections (7.4% versus 0%, P = 0.001). Patients that developed surgical site infection had equivalent rates of smoking and diabetes, as well as equivalent abdominal AIS and wound class compared to those who did not develop surgical site infection. Hospital and ICU LOS, ventilator days, ISS, and mortality were equivalent between METH positive and negative patients. Rates of other infectious complications were the same between groups. CONCLUSIONS: Methamphetamine use is associated with an increased rate of surgical site infection after trauma laparotomy. Other serious complications and mortality were not affected by METH use.

TBC1D3 regulates the payload and biological activity of extracellular vesicles that mediate tissue repair.

Healthy repair of cutaneous injury is a coordinated response of inflammatory cells, secreted factors, and biologically active extracellular vesicles (EVs). Although constitutive release of EVs into biologic fluids is a hallmark of cultured cells and tumors, their payload and biologic activity appears to be tightly regulated. We show that Tre-2/Bub2/Cdc16 (TBC1) domain family member 3 (TBC1D3) drives the release of an EV population that causes a decrease in phosphorylation of the transcription factor signal transducer and activator of transcription 3 in naive recipient cells. To explore the biologic activity of EVs in vivo, we used a mouse model of sterile subcutaneous inflammation to determine the payload and biologic activity of EVs released into the microenvironment by committed myeloid lineages and stroma. Expression of TBC1D3 in macrophages altered the payload of their released EVs, including RNA-binding proteins, molecular motors, and proteins regulating secretory pathways. A wound-healing model demonstrated that closure was delayed by EVs released under the control of TBC1D3. We show that modulating the secretory repertoire of a cell regulates EV payload and biologic activity that affects outcomes in tissue repair and establishes a strategy for modifying EVs mediating specific biologic responses.-Qin, S., Dorschner, R. A., Masini, I., Lavoie-Gagne, O., Stahl, P. D., Costantini, T. W., Baird, A., Eliceiri, B. P. TBC1D3 regulates the payload and biological activity of extracellular vesicles that mediate tissue repair.

CHRFAM7A reduces monocyte/macrophage migration and colony formation in vitro.

OBJECTIVE AND DESIGN: CHRFAM7A is a unique human gene that encodes a dominant negative inhibitor of the α7 nicotinic acetylcholine receptor. We have recently shown that CHRFAM7A is expressed in human leukocytes, increases cel-cell adhesion, and regulates the expression of genes associated with leukocyte migration. MATERIAL: Human THP-1, RAW264.7 and HEK293 cells. METHODS: Cell migration, cell proliferation and colony formation in soft agar to compare the biological activity of vector vs. CHRFAM7A-transduced cells. RESULTS: We show that gene delivery of CHRFAM7A into the THP-1 human monocytic cell line reduces cell migration, reduces chemotaxis to monocyte chemoattractant protein, and reduces colony formation in soft agar. CONCLUSION: Taken together, the findings demonstrate that CHRFAM7A regulates the biological activity of monocytes/macrophages to migrate and undergo anchorage-independent growth in vitro.

The Effects of Cross-Border Transport on Patients With Tibia Fractures.

BACKGROUND: Tibia fractures are common after trauma. Prior studies have shown that delays in treatment are associated with poor outcomes. A subpopulation of our patients are transported from Mexico, adding barriers to prompt care. We hypothesized that patients with tibia fractures crossing from Mexico would have delays in treatment and subsequently worse outcomes. METHODS: The trauma registry of an American College of Surgeons-verified level 1 trauma center was retrospectively reviewed for all tibia fractures admitted from 2010 to 2015. Data collection included demographics, country of injury, characterization of injuries, interventions, complications, and outcomes. Patients were subdivided into those injured in the United States and in Mexico, and the two groups were compared. RESULTS: A total of 498 patients were identified, 440 from the United States and 58 from Mexico. Mexico patients were more severely injured overall, with higher injury severity scores and a higher percentage of patients with abbreviated injury scale scores ≥3 for both head and chest regions. Mexico patients had longer times from injury to admission, as well as increased times to both debridement of open fractures and operative fixation after admission. On subgroup analysis of patients with isolated tibia fractures (other system abbreviated injury scale < 3), times from arrival to treatment and injury severity score were no longer statistically different. CONCLUSIONS: Patients crossing the border from Mexico with tibia fractures have delays in time to admission and from admission to operative management, although this is primarily due to other severe injuries. Ongoing systems development is required to minimize delays in care and optimize outcomes.

Open reading frame mining identifies a TLR4 binding domain in the primary sequence of ECRG4.

The embedding of small peptide ligands within large inactive pre-pro-precursor proteins encoded by orphan open reading frames (ORFs) makes them difficult to identify and study. To address this problem, we generated oligonucleotide (< 100-400 base pair) combinatorial libraries from either the epidermal growth factor (EGF) ORF that encodes the > 1200 amino acid EGF precursor protein or the orphan ECRG4 ORF, that encodes a 148 amino acid Esophageal Cancer Related Gene 4 (ECRG4), a putative cytokine precursor protein of up to eight ligands. After phage display and 3-4 rounds of biopanning for phage internalization into prostate cancer epithelial cells, sequencing identified the 53-amino acid EGF ligand encoded by the 5' region of the EGF ORF and three distinct domains within the primary sequence of ECRG4: its membrane targeting hydrophobic signal peptide, an unanticipated amino terminus domain at ECRG437-63 and a C-terminus ECRG4133-148 domain. Using HEK-blue cells transfected with the innate immunity receptor complex, we show that both ECRG437-63 and ECRG4133-148 enter cells by interaction with the TLR4 immune complex but neither stimulate NFkB. Taken together, the results help establish that phage display can be used to identify cryptic domains within ORFs of the human secretome and identify a novel TLR4-targeted internalization domain in the amino terminus of ECRG4 that may contribute to its effects on cell migration, immune cell activation and tumor suppression.

Exosomes in postshock mesenteric lymph are key mediators of acute lung injury triggering the macrophage activation via Toll-like receptor 4.

Acute lung injury (ALI) is a common cause of morbidity in patients after severe injury due to dysregulated inflammation, which is believed to be driven by gut-derived inflammatory mediators carried via mesenteric lymph (ML). We have previously demonstrated that nano-sized extracellular vesicles, called exosomes, secreted into ML after trauma/hemorrhagic shock (T/HS) have the potential to activate immune cells in vitro Here, we assess the function of ML exosomes in the development of T/HS-induced ALI and the role of TLR4 in the ML exosome-mediated inflammatory response. ML exosomes isolated from rats subjected to T/HS stimulated NF-κB activation and caused proinflammatory cytokine production in alveolar macrophages. In vivo experiments revealed that intravenous injection of exosomes harvested after T/HS, but not before shock, caused recruitment of inflammatory cells in the lung, increased vascular permeability, and induced histologic ALI in naive mice. The exosome-depleted supernatant of ML had no effect on in vitro and in vivo inflammatory responses. We also demonstrated that both pharmacologic inhibition and genetic knockout of TLR4 completely abolished ML exosome-induced cytokine production in macrophages. Thus, our findings define the critical role of exosomes secreted into ML as a critical mediator of T/HS-induced ALI through macrophage TLR4 activation.-Kojima, M., Gimenes-Junior, J. A., Chan, T. W., Eliceiri, B. P., Baird, A., Costantini, T. W., Coimbra, R. Exosomes in postshock mesenteric lymph are key mediators of acute lung injury triggering the macrophage activation via Toll-like receptor 4.

Readmissions After Acute Hospitalization for Traumatic Brain Injury.

BACKGROUND: Traumatic brain injury (TBI) is associated with functional deficits, impaired cognition, and medical complications that continue well after the initial injury. Many patients seek medical care at other health care facilities after discharge, rather than returning to the admitting trauma center, making assessment of readmission rates and readmission diagnoses difficult to determine. The objective of this study was to determine the incidence and factors associated with readmission to any acute care hospital after an index admission for TBI. MATERIALS AND METHODS: The Nationwide Readmission Database was queried for all patients admitted with a TBI during the first 3 mo of 2015. Nonelective readmissions for this population were then collected for the remainder of 2015. Patients who died during the index admission were excluded. Demographic data, injury mechanism, type of TBI, the number of readmissions, days from discharge to readmission, readmission diagnosis, and mortality were studied. RESULTS: Of the 15,277 patients with an index admission for TBI, 5296 patients (35%) required at least 1 readmission. Forty percent of readmissions occurred within the first 30 d after discharge from the index trauma admission. The most common primary diagnosis on readmission was SDH, followed by septicemia, urinary tract infection, and aspiration. Readmission rates increased with age, with 75% of readmissions occurring in patients aged >65 y. Initial discharge to a skilled nursing facility (Relative Risk [RR], 1.60) or leaving the hospital against medical advice (RR, 1.59) increased the risk of readmission. Patients with fall as their mechanism of injury and a subdural hematoma were more likely to require readmission compared with other types of mechanisms with TBI (RR, 1.59 and RR, 1.21, respectively; P < 0.001). Notably, the first readmission was to a different hospital for 39.5% of patients and 46.9% of patients had admissions to at least one facility outside that of their original presentation. CONCLUSIONS: Hospital readmission is common for patients discharged after TBI. Elderly patients who fall with resultant subdural hematoma are at especially high risk for complications and readmission. Understanding potentially preventable causes for readmission can be used to guide discharge planning pathways to decrease morbidity in this patient population.

Prophylactic enoxaparin doses may be inadequate in patients undergoing abdominal cancer surgery.

BACKGROUND: The incidence of venous thromboembolism has increased in patients following cancer surgery despite the increased use of prophylactic anticoagulants, suggesting standard doses may be inadequate. We sought to determine the adequacy of enoxaparin prophylaxis in patients undergoing abdominal cancer surgery. METHODS: Peak and trough anti-Xa levels were measured in patients receiving enoxaparin thromboprophylaxis (40 mg daily or 30 mg twice daily, at the surgeon's discretion) after undergoing open abdominal cancer surgery at a single institution. RESULTS: Fifty-five patients received enoxaparin 40 mg daily (group 1), 18 received 30 mg twice daily (group 2; total n = 73). There were no significant differences in gender, age, body mass index, creatinine clearance, diagnosis, or procedure between the two groups. Thirty-nine patients (53.4%) had inadequate peak anti-Xa levels (<0.2 IU/mL) and 69 patients (94.5%) had inadequate trough levels (≤0.1 IU/mL). Group 2 had lower mean peak levels (0.14 ± 0.02 IU/mL) than group 1 (0.22 ± 0.01, P = 0.003), and higher mean trough levels (0.06 ± 0.017) than group 1 (0.02 ± 0.004, P = 0.033). Group 2 had lower incidence of adequate peak anti-Xa levels than group 1 when adjusting for gender, age, body mass index, and preoperative creatinine clearance (OR 0.23, P = 0.039). CONCLUSIONS: The majority of patients had inadequate anti-Xa levels following abdominal cancer surgery, calling into question standard prophylactic enoxaparin dosing.

Enteric glia cells are critical to limiting the intestinal inflammatory response after injury.

Vagal nerve stimulation (VNS) has been shown to limit intestinal inflammation following injury; however, a direct connection between vagal terminals and resident intestinal immune cells has yet to be identified. We have previously shown that enteric glia cell (EGC) expression is increased after injury through a vagal-mediated pathway to help restore gut barrier function. We hypothesize that EGCs modulate immune cell recruitment following injury and relay vagal anti-inflammatory signals to resident immune cells in the gut. EGCs were selectively ablated from an isolated segment of distal bowel with topical application of benzalkonium chloride (BAC) in male mice. Three days following BAC application, mice were subjected to an ischemia-reperfusion injury (I/R) by superior mesenteric artery occlusion for 30 min. VNS was performed in a separate cohort of animals. EGC+ and EGC- segments were compared utilizing histology, flow cytometry, immunohistochemistry, and intestinal permeability. VNS significantly reduced immune cell recruitment after I/R injury in EGC+ segments with cell percentages similar to sham. VNS failed to limit immune cell recruitment in EGC- segments. Histologic evidence of gut injury was diminished with VNS application in EGC+ segments, whereas EGC- segments showed features of more severe injury. Intestinal permeability increased following I/R injury in both EGC+ and EGC- segments. Permeability was significantly lower after VNS application compared with injury alone in EGC+ segments only (95.1 ± 30.0 vs. 217.6 ± 21.7 µg/ml, P < 0.05). Therefore, EGC ablation uncouples the protective effects of VNS, suggesting that vagal-mediated signals are translated to effector cells through EGCs.NEW & NOTEWORTHY Intestinal inflammation is initiated by local immune cell activation and epithelial barrier breakdown, resulting in the production of proinflammatory mediators with subsequent leukocyte recruitment. Vagal nerve stimulation (VNS) has been shown to limit intestinal inflammation following injury; however, direct connection between vagal terminals and resident intestinal immune cells has yet to be identified. Here, we demonstrate that intact enteric glia cells are required to transmit the gut anti-inflammatory effects of VNS.

The Response to Burn Injury in Mice With Human Hematolymphoid Systems.

OBJECTIVE: To develop an animal model of injury that more closely represents the human inflammatory cell response to injury. BACKGROUND: Because the mouse inflammatory response to burn injury cannot account for the contribution of human-specific genes, animal models are needed to more closely recapitulate the human inflammatory response and improve the translational impact of injury research. To this end, we hypothesized that the human inflammatory cell response to injury could be selectively assessed after severe burn injury using humanized mice. METHODS: NOD-Scid-IL2Rγ null mice were transplanted with human hematopoietic CD34+ progenitor cells; their engraftment confirmed and then subjected to 30% total body surface area steam burn injury. Blood, bone marrow, and lung tissue were collected 4 hours after injury and human inflammatory cell mobilization analyzed using flow cytometry and immunohistochemistry. RESULTS: Burn injury caused mobilization of human inflammatory cells into the systemic circulation. Next, burn injury was accompanied by evidence of histologic lung injury and concomitant mobilization of human CD45+ immune cells into the lung that were associated with increased trafficking of human CD11b+ myeloid cells. CONCLUSIONS: These experiments are the first to demonstrate the suitability of humanized mice for injury research. They offer the possibility to address very specific research questions that are not amenable to traditional mouse models of injury, for example, the emerging role of certain human-specific genes that are either unrepresented or totally absent, from the mouse genome.

CHRFAM7A: a human-specific α7-nicotinic acetylcholine receptor gene shows differential responsiveness of human intestinal epithelial cells to LPS.

The human genome contains a unique, distinct, and human-specific α7-nicotinic acetylcholine receptor (α7nAChR) gene [CHRNA7 (gene-encoding α7-nicotinic acetylcholine receptor)] called CHRFAM7A (gene-encoding dup-α7-nicotinic acetylcholine receptor) on a locus of chromosome 15 associated with mental illness, including schizophrenia. Located 5' upstream from the "wild-type" CHRNA7 gene that is found in other vertebrates, we demonstrate CHRFAM7A expression in a broad range of epithelial cells and sequenced the CHRFAM7A transcript found in normal human fetal small intestine epithelial (FHs) cells to prove its identity. We then compared its expression to CHRNA7 in 11 gut epithelial cell lines, showed that there is a differential response to LPS when compared to CHRNA7, and characterized the CHRFAM7A promoter. We report that both CHRFAM7A and CHRNA7 gene expression are widely distributed in human epithelial cell lines but that the levels of CHRFAM7A gene expression vary up to 5000-fold between different gut epithelial cells. A 3-hour treatment of epithelial cells with 100 ng/ml LPS increased CHRFAM7A gene expression by almost 1000-fold but had little effect on CHRNA7 gene expression. Mapping the regulatory elements responsible for CHRFAM7A gene expression identifies a 1 kb sequence in the UTR of the CHRFAM7A gene that is modulated by LPS. Taken together, these data establish the presence, identity, and differential regulation of the human-specific CHRFAM7A gene in human gut epithelial cells. In light of the fact that CHRFAM7A expression is reported to modulate ligand binding to, and alter the activity of, the wild-type α7nAChR ligand-gated pentameric ion channel, the findings point to the existence of a species-specific α7nAChR response that might regulate gut epithelial function in a human-specific fashion.

Mice engrafted with human hematopoietic stem cells support a human myeloid cell inflammatory response in vivo.

Mice engrafted with human CD34+ hematopoietic stem and progenitor cells (CD34+ -HSPCs) have been used to study human infection, diabetes, sepsis, and burn, suggesting that they could be highly amenable to characterizing the human inflammatory response to injury. To this end, human leukocytes infiltrating subcutaneous implants of polyvinyl alcohol (PVA) sponges were analyzed in immunodeficient NSG mice reconstituted with CD34+ -HSPCs. It was reported that human CD45+ (hCD45+ ) leukocytes were present in PVA sponges 3 and 7 days postimplantation and could be localized within the sponges by immunohistochemistry. The different CD45+ subtypes were characterized by flow cytometry and the profile of human cytokines they secreted into PVA wound fluid was assessed using a human-specific multiplex bead analyses of human IL-12p70, TNFα, IL-10, IL-6, IL1ß, and IL-8. This enabled tracking the functional contributions of HLA-DR+ , CD33+ , CD19+ , CD62L+ , CD11b+ , or CX3CR1+ hCD45+ infiltrating inflammatory leukocytes. PCR of cDNA prepared from these cells enabled the assessment and differentiation of human, mouse, and uniquely human genes. These findings support the hypothesis that mice engrafted with CD34+ -HSPCs can be deployed as precision avatars to study the human inflammatory response to injury.