INTRODUCTION The clinical course of coronavirus 2019 (COVID-19) is heterogeneous, ranging from mild to severe multiorgan failure and death. In this study, we analyzed cell-free DNA (cfDNA) as a biomarker of injury to define the sources of tissue injury that contribute to such different trajectories. METHODS We conducted a multicenter prospective cohort study to enroll patients with COVID-19 and collect plasma samples. Plasma cfDNA was subject to bisulfite sequencing. A library of tissue-specific DNA methylation signatures was used to analyze sequence reads to quantitate cfDNA from different tissue types. We then determined the correlation of tissue-specific cfDNA measures to COVID-19 outcomes. Similar analyses were performed for healthy controls and a comparator group of patients with respiratory syncytial virus and influenza. RESULTS We found markedly elevated levels and divergent tissue sources of cfDNA in COVID-19 patients compared with patients who had influenza and/or respiratory syncytial virus and with healthy controls. The major sources of cfDNA in COVID-19 were hematopoietic cells, vascular endothelium, hepatocytes, adipocytes, kidney, heart, and lung. cfDNA levels positively correlated with COVID-19 disease severity, C-reactive protein, and D-dimer. cfDNA profile at admission identified patients who subsequently required intensive care or died during hospitalization. Furthermore, the increased cfDNA in COVID-19 patients generated excessive mitochondrial ROS (mtROS) in renal tubular cells in a concentration-dependent manner. This mtROS production was inhibited by a TLR9-specific antagonist. CONCLUSION cfDNA maps tissue injury that predicts COVID-19 outcomes and may mechanistically propagate COVID-19–induced tissue injury. FUNDING Intramural Targeted Anti–COVID-19 grant, NIH.

Life-threatening hemoptysis is commonly encountered in the ICU and its management can be challenging even for experienced clinicians. Depending on the etiology and severity, one can tailor the treatment modality and therapeutic intervention(s). The grading of severity of hemoptysis varies greatly in the literature; however, unlike hemorrhage in other scenarios, small amounts of blood can significantly impair oxygenation and ventilation leading to cardiovascular collapse. Importantly, the initial evaluation and management should focus on airway and hemodynamic stabilization along with maintenance of oxygenation and ventilation. In this review, we discuss commonly encountered etiologies, vascular anatomy, diagnostic evaluation, and therapeutic interventions. We examine the evolving trends in etiologies of life-threating hemoptysis over the years. The role of flexible and rigid bronchoscopy as both a diagnostic and therapeutic modality is explored, as well as the use and indications of several bronchoscopic techniques, such as topical hemostatic agents, endobronchial tamponade, and tranexamic acid (TXA). In addition, we assess the use of multi-row detector computed tomography as the initial rapid diagnostic method of choice and its use in planning for definitive treatment. The efficacy and long-term results of bronchial artery embolization (BAE) are evaluated, as well as indications for surgical intervention. Furthermore, the importance of a multidisciplinary approach is emphasized. The necessary interplay between intensivists, consultative services, and radiologists is described in detail and an algorithmic management strategy incorporating the above is outlined. Given the complexity in management of life-threatening hemoptysis, this paper aims to summarize the available diagnostic and therapeutic methods and provide a standardized approach for the management of patients with this often difficult to treat condition.

Plasma donor-derived cell-free DNA (dd-cfDNA) is a sensitive biomarker for the diagnosis of acute rejection in lung transplant recipients; however, differences in dd-cfDNA levels between single and double lung transplant remains unknown. We performed an observational analysis that included 221 patients from two prospective cohort studies who had serial measurements of plasma dd-cfDNA at the time of bronchoscopy and pulmonary function testing, and compared dd-cfDNA between single and double lung transplant recipients across a range of disease states. Levels of dd-cfDNA were lower for single vs. double lung transplant in stable controls (median [IQR]: 0.15% [0.07, 0.44] vs. 0.46% [0.23, 0.74], p < .01) and acute rejection (1.06% [0.75, 2.32] vs. 1.78% [1.18, 5.73], p = .05). Doubling dd-cfDNA for single lung transplant to account for differences in lung mass eliminated this difference. The area under the receiver operating curve (AUC) for the detection of acute rejection was 0.89 and 0.86 for single and double lung transplant, respectively. The optimal dd-cfDNA threshold for the detection of acute rejection was 0.54% in single lung and 1.1% in double lung transplant. In conclusion, accounting for differences in dd-cfDNA in single versus double lung transplant is key for the interpretation of dd-cfDNA testing in research and clinical settings.

Pulmonary chronic graft-versus-host disease (PcGvHD) is a devastating complication of allogeneic hematopoietic stem cell transplant (HCT). The 2014 NIH chronic GvHD (cGvHD) Consensus Criteria (NIH Criteria) only captures bronchiolitis obliterans syndrome (BOS). In this study, we adapted the 2019 Criteria of chronic lung allograft dysfunction (CLAD) to define novel phenotypes of PcGvHD and compared the performance of this criteria with the NIH Criteria to identify high-risk PcGvHD patients. We reviewed consecutive patients in a cGvHD natural history protocol (NCT00092235) and adapted the 2019 CLAD Criteria (the Adapted Criteria) to define PcGvHD as post-HCT FEV1 &lt;80% predicted value, with four phenotypes: obstructive, restrictive, mixed obstructive/restrictive and undefined. An independent adjudication committee evaluated subjects for diagnosis and phenotyping. We identified 166 (47.4%) patients who met the Adapted Criteria, including obstructive (n = 12, 3.4%), restrictive (n=67, 19.1%), mixed obstruction/restriction (n = 47, 13.4%) and undefined (n = 40, 11.4%). In these patients, less than half (n= 78) met the NIH criteria for BOS (NIH+), the rest (n=88) did not (NIH-). The NIH- subjects showed increased risk of death compared to those without PcGvHD (HR = 1.88, 95%CI = 1.20-2.95, p = 0.006) that was similar to NIH+ subjects (p = 0.678). Our study demonstrated the potential of the Adapted Criteria in identifying high risk PcGvHD patients that have been missed by the NIH Criteria. The Adapted Criteria could become a valuable tool to better phenotype and study lung disease in cGvHD.

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