Association of Prehospital Neck Wound Survivability and Battlefield Medical Evacuation Time in Afghanistan.

INTRODUCTION: The U.S. Military's Golden Hour policy led to improved warfighter survivability during the Global War on Terror. The policy's success is well-documented, but a categorical evaluation and stratification of medical evacuation (MEDEVAC) times based on combat injury is lacking. METHODS: We queried the Department of Defense Joint Trauma System Prehospital Trauma Registry for casualties with documented penetrating neck trauma in Afghanistan requiring battlefield MEDEVAC from June 15, 2009, through February 1, 2021. Casualties were excluded if the time from the point of injury to reach higher level medical care was not documented, listed as zero, or exceeded 4 hours. They were also excluded if demographic data were incomplete or deemed unreliable or if their injuries occurred outside of Afghanistan.We designed a logistic regression model to test for associations in survivability, adjusting for composite injury severity score, patient age group, and type of next higher level of care reached. We then used our model to interpolate MEDEVAC times associated with 0.1%, 1%, and 10% increased risk of death for an incapacitated casualty with penetrating neck trauma. RESULTS: Of 1,147 encounters, 444 casualties met inclusion criteria. Of these casualties, 430 (96.9%) survived to discharge. Interpolative analysis of our multivariable logistic regression model showed that MEDEVAC times ≥8 minutes, ≥53 minutes, and ≥196 minutes are associated with a 0.1%, 1%, and 10% increased risk of mortality from baseline, respectively. CONCLUSIONS: Our data characterize the maximum MEDEVAC times associated with 0.1%, 1%, and 10% increased risk of death from baseline survivability for penetrating battlefield neck trauma in Afghanistan.

Role of epigenetics in innate lymphoid cells.

Epigenetics plays a crucial role in gene regulation and cell function without changing the DNA sequence. The process of differentiation in eukaryotes during cellular morphogenesis is a paradigm of epigenetic change; stem cells develop into pluripotent cell lines in the embryo, eventually becoming terminally developed cells. Recently, epigenetic changes were shown to play an important role in immune cell development, activation and differentiation, which impacts chromatin remodeling, DNA methylation, post-translational histone modifications and small or lncRNA engagement. Innate lymphoid cells (ILCs) are newly identified immune cells that lack antigen receptors. ILCs differentiate from hematopoietic stem cells via multipotent progenitor stages. In this editorial, the authors discuss the epigenetic regulation of ILC differentiation and function.

Prehospital Pharmacotherapy in Moderate and Severe Traumatic Brain Injury: A Systematic Review.

BACKGROUND: Traumatic brain injury (TBI) affects civilian and military populations with high morbidity and mortality rates and devastating sequelae. As the US military shifts its operational paradigm to prepare for future large-scale combat operations, the need for prolonged casualty care is expected to intensify. Identifying efficacious prehospital TBI management strategies is therefore vital. Numerous pharmacotherapies are beneficial in the inpatient management of TBI, including beta blockers, calcium channel blockers, statins, and other agents. However, their utility in prehospital management of moderate or severe TBI is not well understood. We performed a systematic review to elucidate agents of potential prehospital benefit in moderate and severe TBI. METHODS: We searched 6 databases from January 2000 through December 2021 without limitations in outcome metrics using a variety of search terms designed to encapsulate all studies pertaining to prehospital TBI management. We identified 2,142 unique articles, which netted 114 studies for full review. Seven studies met stringent inclusion criteria for our aims. RESULTS: Studies meeting inclusion criteria assessed tranexamic acid (TXA) (n=6) and ethanol (n=1). Of the TXA studies, 3 were randomized controlled trials, 2 were retrospective cohort studies, 1 was a prospective cohort study, and 1 was a meta-analysis. Notably absent were papers investigating therapeutics shown to be beneficial in inpatient hospital treatment of TBI. Overall, data suggest TXA administration is potentially beneficial in moderate or severe TBI with or without intracranial hemorrhage. Severe TBI with or without penetrating trauma was associated with worse overall outcomes, regardless of TXA use. CONCLUSION: Effective interventions for treating moderate or severe TBI are lacking. TXA is the most widely studied pharmacologic intervention and appears to offer some benefit without adverse effects in moderate TBI (with or without intracranial hemorrhage) in the pre-hospital setting despite heterogeneous results. Limitations of these studies include heterogeneity in outcome metrics, patient populations, and circumstances of TXA use. We identified a gap in the literature in translating agents with demonstrated inpatient benefit to the prehospital setting. Further investigation into these and other novel therapeutic options in the prehospital arena is crucial to improving clinical outcomes in TBI.

Military Medical Role in Civilian Disaster.

US military medical units have responded to natural disasters (eg, hurricanes, earthquakes), relieved overwhelmed civilian health care systems (eg, during the COVID-19 pandemic), and provided support to stabilization efforts after civil unrest. The military will continue to assist civilian agencies with future medical response to similar disasters, contagious outbreaks, or even terrorist attacks. The keys to an effective disaster response are unity of effort, prior coordination, and iterative practice during military-civilian exercises to identify strengths and areas of improvement. Critical care advanced practice nurses are likely to work concurrently with military medical colleagues in multiple scenarios in the future; therefore, it is important for these nurses to understand the capacities and limitations of military medical assets. This article describes the capabilities and collaboration needed between civilian and military medical assets during a variety of disaster scenarios.

Blood Product Administration During the Role 1 Phase of Care: The Prehospital Trauma Registry Experience.

BACKGROUND: The majority of combat deaths occur in the prehospital setting. Efforts to increase survival including blood transfusions are made in the prehospital setting. The blood products available in the Role 1 setting include whole blood (WB), red blood cells (RBCs), fresh frozen plasma (FFP), and lyophilized (freeze-dried) plasma (FDP). METHODS: This is a secondary analysis of a previously published dataset within the Prehospital Trauma Registry (PHTR) from 2003 through May 2019. Deterministic linking was used when possible with the DoD Trauma Registry for outcome data. Descriptive statistics were used to analyze the data. RESULTS: We identified 1,357 patient encounters in the PHTR. Within that group, 28 patients received a prehospital blood product, with 41 total administrations: WB (18), RBCs (12), FFP (6), FDP (3), and blood not otherwise specified (2). Outcome data were available for 17 of the 28 patients. The median injury severity score was 20, with the thorax being the most frequent seriously injured body region. Most (94%) patients survived to discharge. The median ICU days was 11 (Interquartile Range [IQR] 3-19), and the median hospital days was 19 (IQR 8-29). The average volume (units) of RBCs was 6.0 (95% CI 1.9-10.1), WB 2.8 (95% CI 0.0-5.6), platelets 0.7 (95% CI 0.0-1.4), and FFP 5.0 (95% CI 1.2-8.8). CONCLUSIONS: The use of prehospital blood products is uncommon in U.S. combat settings. Patients who received blood products sustained severe injuries but had a high survival rate. Given the infrequent but critical use and potentially increased need for adequate prolonged casualty care in future near-peer conflicts, optimizing logistical chain circulation is required.

Characterizing pediatric supermassive transfusion and the contributing injury patterns in the combat environment.

BACKGROUND: Trauma is the leading cause of pediatric mortality in the United States. Often, these patients require supermassive transfusion (SMT), which we define as receipt of >80 mL/kg blood products, double the proposed volume for standard pediatric massive transfusion (MT). Evaluating the blood volumes, injury patterns, clinical findings, and prehospital interventions predictive for SMT are critical to reducing pediatric mortality. We describe the pediatric casualties, injury patterns, and clinical findings that comprise SMT. METHODS: We retrospectively analyzed pediatric trauma data from the Department of Defense Trauma Registry from January 2007-2016. We stratified patients into two cohorts based on blood products received in the first 24 h after injury: 1) those who received 40-80 mL/kg (MT), or 2) those who received >80 mL/kg (SMT). We evaluated demographics, injury patterns, prehospital interventions, and clinical findings. RESULTS: Our original dataset included 3439 pediatric casualties. We identified 536 patients who met inclusion parameters (receipt of ≥40 mL/kg of blood products [whole blood, packed red blood cells, fresh frozen plasma, platelets, or cryoprecipitate]). The MT cohort included 271 patients (50.6%), and the SMT cohort comprised 265 patients (49.4%). Survival to discharge was significantly lower (78% for SMT, 86% for MT; p < 0.011) in the SMT cohort. Multivariable analysis of injury patterns revealed serious injuries (Abbreviated Injury Scale 3-6) to the extremities (OR 2.13, 95% CI 1.45-3.12) and abdomen (OR 1.65, 1.08-2.53) were associated with SMT. Wound dressings (41% versus 29%; p = 0.003), tourniquets (23% vs 12%; p = 0.001), and IO access (17% vs 10%; p = 0.013) were more common in the SMT group. Age-adjusted hypotension was significantly higher in the SMT group (41%, n = 100 vs 23%, n = 59; p < 0.001) with no statistical difference detected in tachycardia (87%, n = 223 vs 87%, n = 228; p = 0.932). CONCLUSIONS: Our research demonstrates that pediatric SMT patients are at increased risk of mortality. Our study highlights the seriousness of extremity injuries in pediatric trauma patients, identifying associations between severe injuries to the extremities and abdomen with the receipt of SMT. Prehospital interventions of wound dressing, tourniquets, and IO access were more frequent in the SMT cohort. Our research determined that hypotension was associated with SMT, but tachycardia was not a reliable predictor of SMT over MT.

A Descriptive Analysis of Battlefield First Responder and Combat Lifesaver Interventions during the Role 1 Phase of Care.

BACKGROUND: Battlefield first responders (BFR) are the first non-medical personnel to render critical lifesaving interventions for combat casualties, especially for massive hemorrhage where rapid control will improve survival. Soldiers receive medical instruction during initial entry training (IET) and unit-dependent medical training, and by attending the Combat Lifesaver (CLS) course. We seek to describe the interventions performed by BFRs on casualties with only BFRs listed in their chain of care within the Prehospital Trauma Registry (PHTR). METHODS: This is a secondary analysis of a dataset from the PHTR from 2003-2019. We excluded encounters with a documented medical officer, medic, or unknown prehospital provider at any time in their chain of care during the Role 1 phase to isolate only casualties with BFR medical care. RESULTS: Of the 1,357 encounters in our initial dataset, we identified 29 casualties that met inclusion criteria. Pressure dressing was the most common intervention (n=12), followed by limb tourniquets (n=4), IV fluids (n=3), hemostatic gauze (n=2), and wound packing (n=2). Bag-valve-masks, chest seals, extremity splints, and nasopharyngeal airways (NPA) were also used (n=1 each). Notably absent were backboards, blizzard blankets, cervical collars, eye shields, pelvic splints, hypothermia kits, chest tubes, supraglottic airways (SGA), intraosseous (I/O) lines, and needle decompression (NDC). CONCLUSIONS: Despite limited training, BFRs employ vital medical skills in the prehospital setting. Our data show that BFRs largely perform medical interventions within the scope of their medical knowledge and training. Better datasets with efficacy and complication data are needed.

Warfighter Personal Protective Equipment and Combat Wounds.

BACKGROUND: Personal protective equipment (PPE) is crucial to force protection and preservation. Innovation in PPE has shifted injury patterns, with protected body regions accounting for decreased proportions of battlefield trauma relative to unprotected regions. Little is known regarding the PPE in use by warfighters at the time of injury. METHODS: We queried the Prehospital Trauma Registry (PHTR) for all encounters from 2003-2019. This is a sub-analysis of casualties with documented PPE at the time of medical encounter. When possible, encounters were linked to the Department of Defense Trauma Registry (DODTR) for outcome data. Serious injuries are defined as an abbreviated injury scale of 3 or greater. RESULTS: Of 1,357 total casualty encounters in the PHTR, 83 were US military with documented PPE. We link 62 of this cohort to DODTR. The median composite Injury Severity Score (ISS) was 6 (Interquartile range (IQR) 4-21), and 11 casualties (18%) had an ISS >25. The most seriously injured body regions were the extremities (21%), head/neck (16%), thorax (16%), and abdomen (10%). PPE worn at time of injury included helmet (91%), eye protection (73%), front (75%) and rear plates (77%), left/right plates (65%), tactical vest (46%), groin protection (12%), neck protection (6%), pelvic shield (3%), and deltoid protection (3%). CONCLUSION: Our data set demonstrates that the extremities were the most commonly injured body region, followed by head/neck, and thorax. PPE designed for the extremities and neck are also among the least commonly worn protective equipment.

The molecular and epigenetic mechanisms of innate lymphoid cell (ILC) memory and its relevance for asthma.

Repetitive exposure of Rag1-/- mice to the Alternaria allergen extract generated a form of memory that elicited an asthma-like response upon a subthreshold recall challenge 3-15 wk later. This memory was associated with lung ICOS+ST2+ ILC2s. Genetic, pharmacologic, and antibody-mediated inhibition and adoptive transfer established an essential role for ILC2s in memory-driven asthma. ATAC-seq demonstrated a distinct epigenetic landscape of memory ILC2s and identified Bach2 and AP1 (JunD and Fosl2) motifs as major drivers of altered gene accessibility. scRNA-seq, gene knockout, and signaling studies suggest that repetitive allergenic stress induces a gene repression program involving Nr4a2, Zeb1, Bach2, and JunD and a preparedness program involving Fhl2, FosB, Stat6, Srebf2, and MPP7 in memory ILC2s. A mutually regulated balance between these two programs establishes and maintains memory. The preparedness program (e.g., Fhl2) can be activated with a subthreshold cognate stimulation, which down-regulates repressors and activates effector pathways to elicit the memory-driven phenotype.

Sprouty2 positively regulates T cell function and airway inflammation through regulation of CSK and LCK kinases.

The function of Sprouty2 (Spry2) in T cells is unknown. Using 2 different (inducible and T cell-targeted) knockout mouse strains, we found that Spry2 positively regulated extracellular signal-regulated kinase 1/2 (ERK1/2) signaling by modulating the activity of LCK. Spry2-/- CD4+ T cells were unable to activate LCK, proliferate, differentiate into T helper cells, or produce cytokines. Spry2 deficiency abrogated type 2 inflammation and airway hyperreactivity in a murine model of asthma. Spry2 expression was higher in blood and airway CD4+ T cells from patients with asthma, and Spry2 knockdown impaired human T cell proliferation and cytokine production. Spry2 deficiency up-regulated the lipid raft protein caveolin-1, enhanced its interaction with CSK, and increased CSK interaction with LCK, culminating in augmented inhibitory phosphorylation of LCK. Knockdown of CSK or dislodgment of caveolin-1-bound CSK restored ERK1/2 activation in Spry2-/- T cells, suggesting an essential role for Spry2 in LCK activation and T cell function.

Optimal identification of human conventional and nonconventional (CRTH2-IL7Rα-) ILC2s using additional surface markers.

BACKGROUND: Human type 2 innate lymphoid cells (ILC2s) are identified by coupled detection of CRTH2 and IL7Rα on lineage negative (Lin-) cells. Type 2 cytokine production by CRTH2-IL7Rα- innate lymphoid cells (ILCs) is unknown. OBJECTIVE: We sought to identify CRTH2-IL7Rα- type 2 cytokine-producing ILCs and their disease relevance. METHODS: We studied human blood and lung ILCs from asthmatic and control subjects by flow cytometry, ELISA, RNA sequencing, quantitative PCR, adoptive transfer to mice, and measurement of airway hyperreactivity by Flexivent. RESULTS: We found that IL-5 and IL-13 were expressed not only by CRTH2+ but also by CRTH2-IL7Rα+ and CRTH2-IL7Rα- (double-negative [DN]) human blood and lung cells. All 3 ILC populations expressed type 2 genes and induced airway hyperreactivity when adoptively transferred to mice. The frequency of type 2 cytokine-positive IL7Rα and DN ILCs were similar to that of CRTH2 ILCs in the blood and lung. Their frequency was higher in asthmatic patients than in disease controls. Transcriptomic analysis of CRTH2, IL7Rα, and DN ILCs confirmed the expression of mRNA for type 2 transcription factors in all 3 populations. Unexpectedly, the mRNA for GATA3 and IL-5 correlated better with mRNA for CD30, TNFR2, ICOS, CCR4, and CD200R1 than for CRTH2. By using a combination of these surface markers, especially CD30/TNFR2, we identified a previously unrecognized ILC2 population. CONCLUSIONS: The commonly used surface markers for human ILC2s leave a majority of type 2 cytokine-producing ILC2s unaccounted for. We identified top GATA3-correlated cell surface-expressed genes in human ILCs by RNA sequencing. These new surface markers, such as CD30 and TNFR2, identified a previously unrecognized human ILC2 population. This ILC2 population is likely to contribute to asthma.

PD-L2 Regulates B-1 Cell Antibody Production against Phosphorylcholine through an IL-5-Dependent Mechanism.

B-1 cells produce natural Abs which provide an integral first line of defense against pathogens while also performing important homeostatic housekeeping functions. In this study, we demonstrate that programmed cell death 1 ligand 2 (PD-L2) regulates the production of natural Abs against phosphorylcholine (PC). Naive PD-L2-deficient (PD-L2-/-) mice produced significantly more PC-reactive IgM and IgA. This afforded PD-L2-/- mice with selectively enhanced protection against PC-expressing nontypeable Haemophilus influenzae, but not PC-negative nontypeable Haemophilus influenzae, relative to wild-type mice. PD-L2-/- mice had significantly increased PC-specific CD138+ splenic plasmablasts bearing a B-1a phenotype, and produced PC-reactive Abs largely of the T15 Id. Importantly, PC-reactive B-1 cells expressed PD-L2 and irradiated chimeras demonstrated that B cell-intrinsic PD-L2 expression regulated PC-specific Ab production. In addition to increased PC-specific IgM, naive PD-L2-/- mice and irradiated chimeras reconstituted with PD-L2-/- B cells had significantly higher levels of IL-5, a potent stimulator of B-1 cell Ab production. PD-L2 mAb blockade of wild-type B-1 cells in culture significantly increased CD138 and Blimp1 expression and PC-specific IgM, but did not affect proliferation. PD-L2 mAb blockade significantly increased IL-5+ T cells in culture. Both IL-5 neutralization and STAT5 inhibition blunted the effects of PD-L2 mAb blockade on B-1 cells. Thus, B-1 cell-intrinsic PD-L2 expression inhibits IL-5 production by T cells and thereby limits natural Ab production by B-1 cells. These findings have broad implications for the development of therapeutic strategies aimed at altering natural Ab levels critical for protection against infectious disease, autoimmunity, allergy, cancer, and atherosclerosis.

Advances in the management of erythropoietic protoporphyria - role of afamelanotide.

Erythropoietic protoporphyria (EPP) and the phenotypically similar disease X-linked protoporphyria (XLPP) are inherited cutaneous porphyrias characterized clinically by acute non-blistering photosensitivity, intolerance to sunlight, and significantly reduced quality of life. They are due to marked overproduction of protoporphyrin (PP) chiefly by erythroblasts and reticulocytes. In EPP, the underlying genetic defect is in the ferrochelatase gene, which encodes the final enzyme in the heme synthetic pathway. In XLPP, the genetic defect is a gain-of-function mutation, usually a four-base deletion, in the gene that encodes the enzyme 5-aminolevulinic acid synthase-2, the first and rate-controlling enzyme of heme synthesis in developing red blood cells. The excess PP causes acute and painful photosensitivity, being activated by light in the long ultraviolet to blue spectrum (380-420 nm, the Soret band). Although several treatments have been proposed, presently no very effective treatment exists for EPP or XLPP. Afamelanotide (Scenesse®) is a first-in-class synthetic analog of α-melanocyte stimulating hormone. Afamelanotide mimics the naturally occurring hormone to increase skin pigmentation by increasing melanin production in melanocytes, resulting in increased sunlight tolerance in those with EPP/XLPP. Afamelanotide is currently approved for use in the European Union and Switzerland, and it is under review in the United States by the Food and Drug Administration for use in patients with EPP/XLPP. This paper provides a review of the clinical characteristics and current therapies for EPP/XLPP. We discuss the pharmacology, clinical efficacy, safety, and tolerability of afamelanotide and summarize the results of several key Phase II and III clinical trials. These data indicate that afamelanotide is a promising therapy for those with these debilitating diseases.

PD-1 suppresses protective immunity to Streptococcus pneumoniae through a B cell-intrinsic mechanism.

Despite the emergence of the programmed cell death 1 (PD-1):PD-1 ligand (PD-L) regulatory axis as a promising target for treating multiple human diseases, remarkably little is known about how this pathway regulates responses to extracellular bacterial infections. We found that PD-1(-/-) mice, as well as wild-type mice treated with a PD-1 blocking Ab, exhibited significantly increased survival against lethal Streptococcus pneumoniae infection following either priming with low-dose pneumococcal respiratory infection or S. pneumoniae-capsular polysaccharide immunization. Enhanced survival in mice with disrupted PD-1:PD-L interactions was explained by significantly increased proliferation, isotype switching, and IgG production by pneumococcal capsule-specific B cells. Both PD-L, B7-H1 and B7-DC, contributed to PD-1-mediated suppression of protective capsule-specific IgG. Importantly, PD-1 was induced on capsule-specific B cells and suppressed IgG production and protection against pneumococcal infection in a B cell-intrinsic manner. To our knowledge, these results provide the first demonstration of a physiologic role for B cell-intrinsic PD-1 expression in vivo. In summary, our study reveals that B cell-expressed PD-1 plays a central role in regulating protection against S. pneumoniae, and thereby represents a promising target for bolstering immunity to encapsulated bacteria.

A real-time polymerase chain reaction assay to detect single nucleotide polymorphisms at codon 171 in the prion gene for the genotyping of scrapie susceptibility in sheep.

The objective of this study was to report a reliable real-time polymerase chain reaction assay compatible with the Roche LightCycler 2.0 capable of genotyping sheep for scrapie susceptibility at codon 171. The single nucleotide polymorphisms (SNPs) in the prion protein gene in sheep that may govern resistance to scrapie at codon 171 encode for lysine (K), histidine (H), glutamine (Q), and arginine (R). A modified proteinase K method for leukocytes or whole blood was used to isolate genomic DNA from sheep blood. Fluoresentric developed and optimized primers and probes for the codon 171 SNP assay. The assay was initially validated using 218 determinations from whole blood of known genotypes with 100% correct identity. The assay was further validated through a whole-blood check test provided annually by the National Veterinary Services Laboratory with a correct identification rate of 100%. From January 2005 to December 2006, 3,672 samples from blood were genotyped at codon 171. The genotypes were QR(171) (n = 1,838, 50.05%), RR(171) (n = 1,423, 38.75%), QQ(171) (n = 407, 11.08%), HR(171) (n = 2, 0.05%), and HQ(171) (n = 2, 0.05%). The combination of this simple extraction method and the novel Fluoresentric assay is very accurate, is capable of identifying all 4 SNPs at codon 171 in one reaction, and has proven to be a useful tool for producers in their selective breeding programs.