Spatial and phenotypic heterogeneity of resident and monocyte-derived macrophages during inflammatory exacerbations leading to pulmonary fibrosis.

Introduction: Genetic mutations in critical nodes of pulmonary epithelial function are linked to the pathogenesis of pulmonary fibrosis (PF) and other interstitial lung diseases. The slow progression of these pathologies is often intermitted and accelerated by acute exacerbations, complex non-resolving cycles of inflammation and parenchymal damage, resulting in lung function decline and death. Excess monocyte mobilization during the initial phase of an acute exacerbation, and their long-term persistence in the lung, is linked to poor disease outcome. Methods: The present work leverages a clinical idiopathic PF dataset and a murine model of acute inflammatory exacerbations triggered by mutation in the alveolar type-2 cell-restricted Surfactant Protein-C [SP-C] gene to spatially and phenotypically define monocyte/macrophage changes in the fibrosing lung. Results: SP-C mutation triggered heterogeneous CD68+ macrophage activation, with highly active peri-injured cells relative to those sampled from fully remodeled and healthy regions. Ingenuity pathway analysis of sorted CD11b-SigF+CD11c+ alveolar macrophages defined asynchronous activation of extracellular matrix re-organization, cellular mobilization, and Apolipoprotein E (Apoe) signaling in the fibrosing lung. Cell-cell communication analysis of single cell sequencing datasets predicted pro-fibrogenic signaling (fibronectin/Fn1, osteopontin/Spp1, and Tgfb1) emanating from Trem2/TREM2 + interstitial macrophages. These cells also produced a distinct lipid signature from alveolar macrophages and monocytes, characterized by Apoe expression. Mono- and di-allelic genetic deletion of ApoE in SP-C mutant mice had limited impact on inflammation and mortality up to 42 day after injury. Discussion: Together, these results provide a detailed spatio-temporal picture of resident, interstitial, and monocyte-derived macrophages during SP-C induced inflammatory exacerbations and end-stage clinical PF, and propose ApoE as a biomarker to identify activated macrophages involved in tissue remodeling.

Pro-Inflammatory Effects of Inhaled Great Salt Lake Dust Particles.

Background: Climatological shifts and human activities have decimated lakes worldwide. Water in the Great Salt Lake, Utah, USA is at near record lows which has increased risks for exposure to windblown dust from dried lakebed sediments. Formal studies evaluating the health effects of inhaled Great Salt Lake dust (GSLD) have not been performed despite the belief that the dust is harmful. The objectives of this study were to illustrate windblown dust events, assess the impact of inhaled dust on the lungs, and to identify mechanisms that could contribute to the effects of GSLD in the lungs. Results: An animation, hourly particle and meteorological data, and images illustrate the impact of dust events on the Salt Lake Valley/Wasatch front airshed. Great Salt Lake sediment and PM2.5 contained metals, lipopolysaccharides, natural and anthropogenic chemicals, and bacteria. Inhalation and oropharyngeal delivery of PM2.5 triggered neutrophilia and the expression of mRNA for Il6, Cxcl1, Cxcl2, and Muc5ac in mouse lungs, was more potent than coal fly ash (CFA) PM2.5, and more cytotoxic to human airway epithelial cells (HBEC3-KT) in vitro. Induction of IL6 and IL8 was replicated in vitro using HBEC3-KT and THP-1 cells. For HBEC3-KT cells, IL6 induction was variably attenuated by EGTA/ruthenium red, the TLR4 inhibitor TAK-242, and deferoxamine, while IL8 was attenuated by EGTA/ruthenium red. Inhibition of mRNA induction by EGTA/ruthenium red suggested roles for transition metals, calcium, and calcium channels as mediators of the responses. Like CFA, GSLD and a similar dust from the Salton Sea in California, activated human TRPA1, M8, and V1. However, only inhibition of TRPV1, TRPV3, and a combination of both channels impacted cytokine mRNA induction in HBEC3-KT cells. Responses of THP1 cells were partially mediated by TLR4 as opposed to TRP channels and mice expressing a "humanized" form of TRPV1 exhibited greater neutrophilia when exposed to GSLD via inhalation. Conclusions: This study suggests that windblown dust from Great Salt Lake and similar lake sediments could pose a risk to humans via mechanisms including the activation of TRPV1/V3, TLR4, and possibly oxidative stress.

Transcriptomic-based roadmap to the healthy and ozone-exposed lung.

The lung is constantly exposed to a myriad of exogenous stressors. Ground-level ozone represents a ubiquitous and extremely reactive anthropogenic toxicant, impacting the health of millions across the globe. While abundant, epidemiological, in vivo, and in vitro data focuses the ozone toxicity in individual cell types (e.g. epithelial type II, alveolar macrophages) or signaling pathways involved in the injury (e.g., akt, glutathione). When appropriately used, bulk and single cell RNA sequencing techniques have the potential to provide complete, and in certain cases unbiased, information of the molecular events taking place in the steady state and injured lung, and even capture the phenotypic diversity of neighboring cells. To this end, this review compiles information pertaining to the latest understanding of lung cell identity and activation in the steady state and ozone exposed lung. In addition, it discusses the value and benefits of multi-omics approaches and other tools developed to predict cell-cell communication and dissect spatial heterogeneity.

Association of Relative Skeletal Immaturity of the Triradiate Cartilage with Increased Proximal Femoral Deformity in Prophylactic Fixation for Slipped Capital Femoral Epiphysis: A Radiographic Study.

INTRODUCTION: The purpose of this study was to describe proximal femoral deformity after contralateral hip prophylactic fixation of slipped capital femoral epiphysis (SCFE) in patients and the association of relative skeletal immaturity with this deformity. METHODS: A retrospective review of patients presenting with a SCFE was conducted from 2009 to 2015. Inclusion criteria were (1) radiographic evidence of a unilateral SCFE treated with in situ fixation, (2) contralateral prophylactic fixation of an unslipped hip, and (3) at least 3 years of follow-up. Measurements were made on radiographs and included greater trochanter height relative to the center of the femoral head, femoral head-neck offset, and femoral neck length. Skeletal maturity was evaluated by assessing the status of the proximal femoral physis and triradiate cartilage (TRC) of the hip, in addition to the length of time to closure of these physes. Values were compared from initial presentation to final follow-up. Statistical analysis included descriptive statistics and linear regression. RESULTS: Twenty-seven patients were included. Bivariable linear regression demonstrated that an increased relative trochanteric overgrowth was associated with TRC width (ß = 3.048, R = 0.585, P = 0.001) and an open TRC (ß = -11.400, R = 0.227, P = 0.012). Time to proximal femoral physis closure (ß = 1.963, R = 0.444, P = 0.020) and TRC closure (ß = 1.983, R = 0.486, P = 0.010) were predictive of increased deformity. In addition, multivariable elimination linear regression demonstrated that TRC width (ß = 3.048, R = 0.585, P = 0.001) was predictive of an increased relative trochanteric overgrowth. DISCUSSION: Patients with an open TRC and increased TRC width are associated with increased relative trochanteric overgrowth when undergoing prophylactic fixation for a unilateral SCFE. Increased caution should be exercised when considering contralateral hip prophylactic fixation in skeletally immature patients presenting with a unilateral SCFE. LEVEL OF EVIDENCE: Level IV, case series.

Telehealth follow-up in the postoperative care of surgically treated pediatric supracondylar humerus fractures.

Supracondylar humerus fractures are a common pediatric orthopedic injury requiring surgery. These patients are typically seen 4 weeks post-op for cast and pin removal followed by an 8-12-week post-op motion check. Our study aimed to limit the number of in-office visits by conducting this last motion check by telehealth. This was a single-surgeon series of consecutive surgically treated supracondylar humerus fractures. The primary outcome was the number of patients who completed their range of motion check remotely. Loss to follow-up at the telehealth visit was compared to a prior cohort for whom the range of motion visit was performed in person. Secondary outcomes included number of patients missing work/school for the in-person vs. telehealth visits and satisfaction with the in-person and telehealth visits. Twenty-two patients were enrolled during the study period. Sixteen (73%) successfully completed their telehealth follow-up, which was similar to the prior in-person cohort. Significantly more parents/children had to take a day off from work/school to attend the in-person visit. No patient required a subsequent in-person visit or referral to physical therapy. A total of 100% of patients reported excellent satisfaction with their telehealth visit. Overall satisfaction was similar comparing the in-person vs. telehealth visits (84% vs. 100% reporting excellent satisfaction, P  = 0.12). Telehealth is a viable option for the postoperative care of surgically treated supracondylar humerus fractures. This approach limits in-office visits and decreases the need for parents/children to miss work/school while maintaining excellent satisfaction scores.