Pediatric Phalanx Fractures.

Phalangeal fractures are extremely common in the pediatric and adolescent populations. The incidence of phalangeal fractures peaks in children ages 10 to 14 years, corresponding to the age in which children begin contact sports. Younger children are more likely to experience crush injuries, whereas older children often sustain phalangeal fractures during sports. The physis is particularly susceptible to fracture because of the biomechanically weak nature of the physis compared with the surrounding ligaments and bone. Phalangeal fractures are identified through a thorough physical examination and are subsequently confirmed with radiographic evaluation. Management of pediatric phalangeal fractures is dependent on the age of the child, the severity of the injury, and the degree of fracture displacement. Nondisplaced fractures are often managed nonsurgically with immobilization, whereas unstable, displaced fractures may require surgery, which is often a closed rather than open reduction and percutaneous pinning.

The independent prognostic value of global epigenetic alterations: An analysis of single-cell ATAC-seq of circulating leukocytes from trauma patients followed by validation in whole blood leukocyte transcriptomes across three etiologies of critical illness.

BACKGROUND: While bulk and single cell transcriptomic patterns in circulating leukocytes from trauma patients have been reported, how these relate to changes in open chromatin patterns remain unstudied. Here, we investigated whether single-cell ATAC-seq would provide further resolution of transcriptomic patterns that align with patient outcomes. METHODS: We performed scATAC-seq on peripheral blood mononuclear cells from four trauma patients at <4 h, 24 h, 72 h post-injury and four matched healthy controls, and extracted the features associated with the global epigenetic alterations. Three large-scale bulk transcriptomic datasets from trauma, burn and sepsis patients were used to validate the scATAC-seq derived signature, explore patient epigenetic heterogeneity (Epigenetic Groups: EG_hi vs. EG_lo), and associate patterns with clinical outcomes in critical illness. FINDINGS: Patient subsets with gene expression patterns in blood leukocytes representative of a high global epigenetic signature (EG_hi) had worse outcomes across three etiologies of critical illness. EG_hi designation contributed independent of the known immune leukocyte transcriptomic responses to patient prognosis (Trauma: HR=0.62 [95% CI: 0.43-0.89, event set as recovery], p=0.01, n=167; Burns: HR=4.35 [95% CI: 0.816-23.2, event set as death], p=0.085, n=121; Sepsis: HR=1.60 [95% CI: 1.10-2.33, event set as death], p=0.013, n=479; Cox proportional hazards regression). INTERPRETATION: The inclusion of gene expression patterns that associate with global epigenetic changes in circulating leukocytes improves the resolution of transcriptome-based patient classification in acute critical illnesses. Early detection of both the global epigenetic signature and the known immune transcriptomic patterns associates with the worse prognosis in trauma, burns and sepsis. FUNDING: This project was supported by an R35 grant from National Institutes of Health: 1R35GM127027-01 (T.B.).

Single-Cell Transcriptomics Reveals Compartment-Specific Differences in Immune Responses and Contributions for Complement Factor 3 in Hemorrhagic Shock Plus Tissue Trauma.

ABSTRACT: Hemorrhagic shock with tissue trauma (HS/T) leads to the activation of a system-wide immune-inflammatory response that involves all organs and body compartments. Recent advances in single-cell analysis permit the simultaneous assessment of transcriptomic patterns in a large number of cells making it feasible to survey the landscape of immune cell responses across numerous anatomic sites. Here, we used single-cell RNA sequencing of leukocytes from the blood, liver, and spleen to identify the major shifts in gene expression by cell type and compartment in a mouse HS/T model. At 6 h, dramatic changes in gene expression were observed across multiple-cell types and in all compartments in wild-type mice. Monocytes from circulation and liver exhibited a significant upregulation of genes associated with chemotaxis and migration and a simultaneous suppression of genes associated with interferon signaling and antigen presentation. In contrast, liver conventional DC exhibited a unique pattern compared with other myeloid cells that included a pronounced increase in major histocompatibility complex class II (MHCII) gene expression. The dominant pattern across all compartments for B and T cells was a suppression of genes associated with cell activation and signaling after HS/T. Using complement factor 3 (C3) knockout mice we unveiled a role for C3 in the suppression of monocyte Major Histocompatibility Complex class II expression and activation of gene expression associated with migration, phagocytosis and cytokine upregulation, and an unexpected role in promoting interferon-signaling in a subset of B and T cells across all three compartments after HS/T. This transcriptomic landscape study of immune cells provides new insights into the host immune response to trauma, as well as a rich resource for further investigation of trauma-induced immune responses and complement in driving interferon signaling.

A road map from single-cell transcriptome to patient classification for the immune response to trauma.

Immune dysfunction is an important factor driving mortality and adverse outcomes after trauma but remains poorly understood, especially at the cellular level. To deconvolute the trauma-induced immune response, we applied single-cell RNA sequencing to circulating and bone marrow mononuclear cells in injured mice and circulating mononuclear cells in trauma patients. In mice, the greatest changes in gene expression were seen in monocytes across both compartments. After systemic injury, the gene expression pattern of monocytes markedly deviated from steady state with corresponding changes in critical transcription factors, which can be traced back to myeloid progenitors. These changes were largely recapitulated in the human single-cell analysis. We generalized the major changes in human CD14+ monocytes into 6 signatures, which further defined 2 trauma patient subtypes (SG1 vs. SG2) identified in the whole-blood leukocyte transcriptome in the initial 12 hours after injury. Compared with SG2, SG1 patients exhibited delayed recovery, more severe organ dysfunction, and a higher incidence of infection and noninfectious complications. The 2 patient subtypes were also recapitulated in burn and sepsis patients, revealing a shared pattern of immune response across critical illness. Our data will be broadly useful to further explore the immune response to inflammatory diseases and critical illness.