Physiologic Response to Exercise or Rhabdomyolysis? Creatine Phosphokinase Elevation in 16 Asymptomatic Firefighters.

BACKGROUND We present a case series of 16 trainee firefighters who presented to the Emergency Department with elevated creatine phosphokinase levels of greater than 14 000 units per liter 3 days after the initiation of intense aerobic exercise. All 16 patients were diagnosed with exercise-induced rhabdomyolysis and were mostly asymptomatic. While exercise-induced rhabdomyolysis often affects untrained individuals who abruptly initiate strenuous exercises, our patients were all physically well-trained and maintained an active training regimen. In review of this unusual case series, we assess the patients' risk factors for exercise-induced rhabdomyolysis and the complications of their elevated creatine phosphokinase levels despite their asymptomatic presentations. CASE REPORT We focus on the exercise routine, hospital admission, and course of treatment for 4 of the 16 patients who gave written consent to participate in the study. Therapy was targeted towards intravenous fluids and the lowering of creatine phosphokinase levels. Patients 1, 2, 3, and 4 were discharged when creatine phosphokinase levels decreased by 17%, 40%, 39%, and 40%, respectively. CONCLUSIONS Given the differing guidelines for diagnosis, treatment, and discharge for asymptomatic exercise-induced rhabdomyolysis, it was unclear if this was a physiologic or pathologic response to exercise, if hospital admission was indicated, and the extent to which creatine phosphokinase had to decrease for discharge. Our aim is to: 1) determine recommendations to prevent muscle injury following exercise, 2) distinguish between physiologic response to exercise and clinically significant muscle damage, and 3) and recommend a course of treatment given asymptomatic presentation.

GMM-Demux: sample demultiplexing, multiplet detection, experiment planning, and novel cell-type verification in single cell sequencing.

Identifying and removing multiplets are essential to improving the scalability and the reliability of single cell RNA sequencing (scRNA-seq). Multiplets create artificial cell types in the dataset. We propose a Gaussian mixture model-based multiplet identification method, GMM-Demux. GMM-Demux accurately identifies and removes multiplets through sample barcoding, including cell hashing and MULTI-seq. GMM-Demux uses a droplet formation model to authenticate putative cell types discovered from a scRNA-seq dataset. We generate two in-house cell-hashing datasets and compared GMM-Demux against three state-of-the-art sample barcoding classifiers. We show that GMM-Demux is stable and highly accurate and recognizes 9 multiplet-induced fake cell types in a PBMC dataset.

Simultaneous Measurement of Surface Proteins and Gene Expression from Single Cells.

Single-cell transcriptomic analysis has become a new and powerful tool to study complex multicellular systems. Single-cell RNA sequencing provides an unbiased classification of heterogeneous cellular states at the transcriptional level, but it does not always correlate to cell-surface protein expression. A recently developed method called cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) simultaneously measures surface proteins and gene expression from single cells. Briefly, based on the existing single-cell sequencing technology, oligonucleotide-labeled antibodies and barcoded primer gel beads are used to bind to corresponding cell-surface proteins and mRNA, respectively. Further, libraries of labeled protein and RNA information are sequenced to integrate cellular protein and transcriptome reads together efficiently. CITE-seq is transforming comprehensive genomic studies into models of causal gene-protein investigation.

Epigenetic Regulation of IL-17-Induced Chemokines in Lung Epithelial Cells.

Epithelial cells are known to have barrier functions in multiple organs and regulate innate immune responses. Airway epithelial cells respond to IL-17 by altering their transcriptional profiles and producing antimicrobial proteins and neutrophil chemoattractants. Although IL-17 has been shown to promote inflammation through stabilizing mRNA of CXCR2 ligands, how IL-17 exerts its downstream effects on its target cells through epigenetic mechanisms is largely unknown. Using primary human bronchial epithelial cells and immortalized epithelial cell line from both human and mouse, we demonstrated that IL-17-induced CXCR2 ligand production is dependent on histone acetylation specifically through repressing HDAC5. Furthermore, the chemokine production induced by IL-17 is strictly dependent on the bromodomain and extraterminal domain (BET) family as BET inhibition abolished the IL-17A-induced proinflammatory chemokine production, indicating a pivotal role of the recognition of acetylated histones. In combination with single-cell RNA-seq analysis, we revealed that the cell lines we employed represent specific lineages and their IL-17 responses were regulated differently by the DNA methylation mechanisms. Taken together, our data strongly support that IL-17 sustains epithelial CXCR2 ligand production through epigenetic regulation and the therapeutic potential of interrupting histone modification as well as the recognition of modified histones could be evaluated in neutrophilic lung diseases.

IL-17 Receptor Signaling in the Lung Epithelium Is Required for Mucosal Chemokine Gradients and Pulmonary Host Defense against K. pneumoniae.

The cytokine IL-17, and signaling via its heterodimeric IL-17RA/IL-17RC receptor, is critical for host defense against extracellular bacterial and fungal pathogens. Polarized lung epithelial cells express IL-17RA and IL-17RC basolaterally. However, their contribution to IL-17-dependent pulmonary defenses in vivo remains to be determined. To address this, we generated mice with conditional deletion of Il17ra or Il17rc in Scgb1a1-expressing club cells, a major component of the murine bronchiolar epithelium. These mice displayed an impaired ability to recruit neutrophils into the airway lumen in response to IL-17, a defect in bacterial clearance upon mucosal challenge with the pulmonary pathogen Klebsiella pneumoniae, and substantially reduced epithelial expression of the chemokine Cxcl5. Neutrophil recruitment and bacterial clearance were restored by intranasal administration of recombinant CXCL5. Our data show that IL-17R signaling in the lung epithelium plays a critical role in establishing chemokine gradients that are essential for mucosal immunity against pulmonary bacterial pathogens.