Use of artificial intelligence-powered ECG to differentiate between cardiac and pulmonary pathologies in patients with acute dyspnoea in the emergency department.

BACKGROUND: Acute dyspnoea is common in acute care settings. However, identifying the origin of dyspnoea in the emergency department (ED) is often challenging. We aimed to investigate whether our artificial intelligence (AI)-powered ECG analysis reliably distinguishes between the causes of dyspnoea and evaluate its potential as a clinical triage tool for comparing conventional heart failure diagnostic processes using natriuretic peptides. METHODS: A retrospective analysis was conducted using an AI-based ECG algorithm on patients ≥18 years old presenting with dyspnoea at the ED from February 2006 to September 2023. Patients were categorised into cardiac or pulmonary origin groups based on initial admission. The performance of an AI-ECG using a transformer neural network algorithm was assessed to analyse standard 12-lead ECGs for accuracy, sensitivity, specificity and area under the receiver operating characteristic curve (AUC). Additionally, we compared the diagnostic efficacy of AI-ECG models with N-terminal probrain natriuretic peptide (NT-proBNP) levels to identify cardiac origins. RESULTS: Among the 3105 patients included in the study, 1197 had cardiac-origin dyspnoea. The AI-ECG model demonstrated an AUC of 0.938 and 88.1% accuracy for cardiac-origin dyspnoea. The sensitivity, specificity and positive and negative predictive values were 93.0%, 79.5%, 89.0% and 86.4%, respectively. The F1 score was 0.828. AI-ECG demonstrated superior diagnostic performance in identifying cardiac-origin dyspnoea compared with NT-proBNP. True cardiac origin was confirmed in 96 patients in a sensitivity analysis of 129 patients with a high probability of cardiac origin initially misdiagnosed as pulmonary origin predicted by AI-ECG. CONCLUSIONS: AI-ECG demonstrated superior diagnostic accuracy over NT-proBNP and showed promise as a clinical triage tool. It is a potentially valuable tool for identifying the origin of dyspnoea in emergency settings and supporting decision-making.

Utility of serum uric acid levels in excluding pulmonary hypertension in severe chronic lung disease: insights from a tertiary care center.

Hyperuricemia is a known predictor of World Health Organization (WHO) Group 1 pulmonary hypertension (PH) (pulmonary arterial hypertension), but its role in excluding PH secondary to chronic lung diseases (WHO Group 3) remains unclear. We retrospectively analyzed data from 323 patients with severe chronic pulmonary diseases who underwent evaluation for lung transplantation at a tertiary medical center between June 2017 and February 2023. We examined the association between hyperuricemia (serum uric acid > 6 mg/dL or > 0.357 mmol/L) and PH [mean pulmonary arterial pressure (MPAP) > 20 mmHg]. Compared to the normouricemia group (n = 211), hyperuricemic patients (n = 112) were more likely to be younger (P = 0.02), male (P < 0.001), and present with PH (P = 0.001) and severe PH (MPAP > 35 mmHg; P < 0.001). These patients also had a higher body mass index (P = 0.004), plasma N-terminal pro-B-type natriuretic peptide (P < 0.001), serum creatinine (P < 0.001), and C-reactive protein levels (P = 0.03). Significant associations with PH included higher body mass index (P = 0.005), uric acid levels (P < 0.001), total lung capacity (P = 0.02), and residual volume (P = 0.01); shorter 6-min walk test distance (P = 0.005); and lower forced expiratory volume in one second (P = 0.006) and diffusing capacity for carbon monoxide (P < 0.001). Multivariate analysis showed elevated uric acid levels remained significantly associated with PH (OR 1.29, 95% CI 1.05-1.58, P = 0.01). In conclusion, normal serum uric acid levels serve as a significant predictor for excluding pulmonary hypertension in patients with severe chronic lung diseases.

Discriminating Benign from Malignant Lung Diseases Using Plasma Glycosaminoglycans and Cell-Free DNA.

We aimed to investigate the use of free glycosaminoglycan profiles (GAGomes) and cfDNA in plasma to differentiate between lung cancer and benign lung disease, in a cohort of 113 patients initially suspected of lung cancer. GAGomes were analyzed in all samples using the MIRAM® Free Glycosaminoglycan Kit with ultra-high-performance liquid chromatography and electrospray ionization triple quadrupole mass spectrometry. In a subset of samples, cfDNA concentration and NGS-data was available. We detected two GAGome features, 0S chondroitin sulfate (CS), and 4S CS, with cancer-specific changes. Based on the observed GAGome changes, we devised a model to predict lung cancer. The model, named the GAGome score, could detect lung cancer with 41.2% sensitivity (95% CI: 9.2-54.2%) at 96.4% specificity (95% CI: 95.2-100.0%, n = 113). When we combined the GAGome score with a cfDNA-based model, the sensitivity increased from 42.6% (95% CI: 31.7-60.6%, cfDNA alone) to 70.5% (95% CI: 57.4-81.5%) at 95% specificity (95% CI: 75.1-100%, n = 74). Notably, the combined GAGome and cfDNA testing improved the sensitivity, compared to cfDNA alone, especially in ASCL stage I (55.6% vs 11.1%). Our findings show that plasma GAGome profiles can enhance cfDNA testing performance, highlighting the applicability of a multiomics approach in lung cancer diagnostics.

Correlation of vitamin A levels in umbilical cord blood with neonatal pulmonary diseases.

OBJECTIVE: To study the relationship between umbilical cord blood vitamin A (VA) and neonatal lung diseases and explore the impact of umbilical cord blood VA on neonatal lung diseases. METHOD: Umbilical vein blood was collected at birth, and its VA content was measured. According to the VA levels in umbilical cord blood, a VA deficiency (VAD) group, a marginal deficiency group and a normal group were created and followed up until 28 days after birth. RESULTS: The umbilical cord blood VA level in the neonatal group with lung disease was 0.13 ± 0.05 mg/L, while the result for the VA level in the non-lung disease group was 0.15 ± 0.05 mg/L. The umbilical cord blood VA levels in the neonatal lung disease group were significantly lower than those in the non-lung disease group. The incidence of neonatal pulmonary diseases was highest in the VAD group, and the incidence decreased as the level of VA in umbilical cord blood increased. Umbilical cord blood VAD and premature birth were found to be independent risk factors for neonatal respiratory disease. CONCLUSION: Umbilical cord blood VAD and premature birth are independent risk factors for neonatal pulmonary diseases. The lower the level of VA in umbilical cord blood, the more susceptible infants will be to neonatal respiratory infections in the neonatal period.

Increased Apolipoprotein B/Apolipoprotein A-I Ratio Is Associated With Decline in Lung Function in Healthy Individuals: The Kangbuk Samsung Health Study.

BACKGROUND: Lung dysfunction and high apolipoprotein B/apolipoprotein A-I (apoB/apoA-I) ratio are both recognized risk factors for cardiovascular disease. However, few studies have examined the association between the apoB/ApoA-I ratio and lung function. Therefore, we investigated whether this ratio is associated with decreased lung function in a large healthy cohort. METHODS: We performed a cohort study on 68,418 healthy Koreans (34,797 males, mean age: 38.1 years) who underwent a health examination in 2019. ApoB/apoA-I ratio was categorized into quartiles. Spirometric values at the fifth percentile in our population were considered the lower limit of normal (LLN), which was used to define lung function impairment. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs), using the lowest quartile as the reference, were estimated to determine lung function impairment. RESULTS: Mean apoB/apoA-I ratio was 0.67 ± 0.21. Subjects with the highest quartile of this ratio had the lowest predicted forced expiratory volume in one second (FEV1%) and forced vital capacity (FVC%) after controlling for covariates (P < 0.001). However, FEV1/FVC ratio was not significantly different among the four quartiles (P = 0.059). Compared with the lowest quartile (Q1, reference), the aORs (95% CI) for FEV1% < LLN across increasing quartiles (from Q2 to Q4) were 1.216 (1.094-1.351), 1.293 (1.156-1.448), and 1.481 (1.311-1.672) (P for trend < 0.001), respectively. Similarly, the aORs for FVC% < LLN compared with the reference were 1.212 (1.090-1.348), 1.283 (1.147-1.436), and 1.502 (1.331-1.695) with increasing quartiles (P for trend < 0.001). However, the aORs for FEV1/FVC < LLN were not significantly different among groups (P for trend = 0.273). CONCLUSION: High apoB/apoA-I ratio was associated with decreased lung function. However, longitudinal follow-up studies are required to validate our findings.

Metabolomic differentiation of benign vs malignant pulmonary nodules with high specificity via high-resolution mass spectrometry analysis of patient sera.

Differential diagnosis of pulmonary nodules detected by computed tomography (CT) remains a challenge in clinical practice. Here, we characterize the global metabolomes of 480 serum samples including healthy controls, benign pulmonary nodules, and stage I lung adenocarcinoma. The adenocarcinoma demonstrates a distinct metabolomic signature, whereas benign nodules and healthy controls share major similarities in metabolomic profiles. A panel of 27 metabolites is identified in the discovery cohort (n = 306) to distinguish between benign and malignant nodules. The discriminant model achieves an AUC of 0.915 and 0.945 in the internal validation (n = 104) and external validation cohort (n = 111), respectively. Pathway analysis reveals elevation in glycolytic metabolites associated with decreased tryptophan in serum of lung adenocarcinoma vs benign nodules and healthy controls, and demonstrates that uptake of tryptophan promotes glycolysis in lung cancer cells. Our study highlights the value of the serum metabolite biomarkers in risk assessment of pulmonary nodules detected by CT screening.

Restrictive allograft syndrome vs bronchiolitis obliterans syndrome: Immunological and molecular characterization of circulating exosomes.

BACKGROUND: Chronic lung allograft dysfunction in lung transplant recipients (LTxRs) has 2 phenotypes: obstructive bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). Our goal was to define distinct immunologic markers of exosomes from LTxRs with BOS or RAS. METHODS: Plasma was collected from LTxRs with BOS (n = 18), RAS (n = 13), and from stable LTxRs (n = 5). Antibodies to lung self-antigens (SAgs) were determined by ELISA. Exosomes were isolated by ultracentrifugation. Donor specific antibodies to HLA were quantified using Luminex. Exosomes were characterized for lung SAgs, transcription factors, 20S proteasome, HLA class I and II, and polymeric immunoglobulin receptor protein using western blot. Exosome miRNA was analyzed using NanoString. The exosome-induced immune response was determined in mice. RESULTS: LTxRs with RAS, but not BOS, had donor specific antibodies at diagnosis. CIITA, NFkB, polymeric immunoglobulin receptor protein, 20S proteasome, HLA-DQ, and HLA-DR were significantly higher in RAS exosomes than in BOS exosomes. RAS plasma had high levels of proinflammatory cytokines and distinct exosomal miRNA. Immunization of C57BL/6 mice with RAS exosomes showed severe inflammation and peribronchial fibrosis, whereas BOS exosomes induced patchy inflammation and fibrosis. CONCLUSION: LTxRs with BOS or RAS had exosomes with distinct molecular and immunologic profiles. RAS samples had a higher concentration of proinflammatory factors, HLA class II, lung SAgs, and antibodies to HLA class II molecules, indicating severe allograft injury. Mice immunized with RAS exosomes developed lesions in airways, pleura, interlobular septum, and alveoli, whereas BOS exosomes induced mild to patchy inflammation with lung fibrosis.

Risk factors for functional decline among survivors of Gram-negative bloodstream infection: A prospective cohort study.

OBJECTIVE: To identify risk factors for functional decline after hospitalization for Gram-negative bacteremia. PATIENTS AND METHODS: A prospective cohort study based on a randomized controlled trial conducted between January 1, 2013 and August 31, 2017 in Israel and Italy. Hospitalized patients with Gram-negative bacteremia who survived until day 90 and were not bedridden at baseline were included. The primary end point was functional decline at 90 days. RESULTS: Five hundred and nine patients were included. The median age of the cohort was 71 years (interquartile range [IQR], 60-80 years), 46.4% (236/509) were male and 352 of 509 (69%) patients were independent at baseline. Functional decline at 90 days occurred in 24.4% of patients (124/509). In multivariable analysis; older age (odds ratio [OR], 1.03; for an one-year increment, 95% confidence interval [CI] 1.01-1.05), functional dependence in instrumental activities of daily living at baseline (OR, 4.64; 95% CI 2.5-8.6), low Norton score (OR, 0.87; 95% CI 0.79-0.96) and underlying comorbidities: cancer (OR, 2.01; 95% CI 1.14-3.55) and chronic pulmonary disease (OR, 2.23 95% CI 1.12-4.42) and longer length of hospital stay (OR 1.09; for one-day increment, 95% CI 1.04-1.15) were associated with functional decline. Appropriate empirical antibiotic treatment was associated with lower rates of functional decline within 90 days (OR, 0.4; 95% CI 0.21-0.78). CONCLUSIONS: Patients surviving bloodstream infections have poor long term trajectories after clinical recovery and hospital discharge. This has vast implications for patients, their family members and health policy makers.

Serum carcinoembryonic antigen elevation in benign lung diseases.

Carcinoembryonic antigen (CEA) is not only used to aid the diagnosis of lung cancer, but also help monitor recurrence and determine the prognosis of lung cancer as well as evaluate the therapeutic efficacy for lung cancer. However, studies have also shown that CEA is present at low levels in the serum of patients with benign lung diseases (BLD), which will interfere with the accurate judgment of the disease. Due to difference in sample size, detection methods, cutoff values and sources of BLD, the positive rate of CEA in BLD is different with different literature. Therefore, it is necessary to define CEA levels in patients of different BLD in a large sample study. 4796 patients with BLD were included in this study. The results showed that the CEA levels of 3.1% (149/4796) patients with BLD were elevated, with three cases exceeds 20 ng/mL (0.06%, 3/4796). The results from the literature showed that BLD had a mean positive rate of 5.99% (53/885) and only two cases had CEA above 20 ng/mL. The CEA elevations mainly distributed in chronic obstructive pulmonary disease (COPD), pneumonitis and interstitial lung disease and significantly correlated with age of patients (OR 2.69, 95% CI 1.94-3.73, p < 0.001). Pulmonary tuberculosis (7/1311, 0.53%) had the lowest positive rate of CEA elevations while pulmonary alveolar proteinosis (6/27, 22.22%) had the highest positive rate. The majority of patients with abnormally elevated CEA levels had multiple underlying diseases, mainly diseases of the circulatory system (42.28% [63/149]), endocrine diseases (26.85% [40/149]), and respiratory or heart failure (24.16% [36/149]. In endocrine diseases, 87.5% (35/40) of patients had diabetes. In conclusion, CEA is present at a low positive rate in the serum of patients with BLD, but few exceed 20 ng/mL. For lung disease patients, if CEA levels rise, we should carry out comprehensive analysis of types of lung diseases, age of patients, and comorbid diseases.

Association between circulating alpha-1 antitrypsin polymers and lung and liver disease.

BACKGROUND: Alpha-1 antitrypsin deficiency (AATD) is considered one of the most common genetic diseases and is characterised by the misfolding and polymerisation of the alpha-1 antitrypsin (AAT) protein within hepatocytes. The relevance of circulating polymers (CP) of AAT in the pathogenesis of lung and liver disease is not completely understood. Therefore, the main objective of our study was to determine whether there is an association between the levels of CP of AAT and the severity of lung and liver disease. METHOD: This was a cross-sectional study in patients with different phenotypes of AATD and controls. To quantify CP, a sandwich ELISA was performed using the 2C1 monoclonal antibody against AAT polymers. Sociodemographic data, clinical characteristics, and liver and lung parameters were collected. RESULTS: A cohort of 70 patients was recruited: 32 Pi*ZZ (11 on augmentation therapy); 29 Z-heterozygous; 9 with other genotypes. CP were compared with a control group of 47 individuals (35 Pi*MM and 12 Pi*MS). ZZ patients had the highest concentrations of CP (p < 0.001) followed by Z heterozygous. The control group and patients with Pi*SS and Pi*SI had the lowest CP concentrations. Pi*ZZ also had higher levels of liver stiffness measurements (LSM) than the remaining AATD patients. Among patients with one or two Z alleles, two patients with lung and liver impairment showed the highest concentrations of CP (47.5 µg/mL), followed by those with only liver abnormality (n = 6, CP = 34 µg/mL), only lung (n = 18, CP = 26.5 µg/mL) and no abnormalities (n = 23, CP = 14.3 µg/mL). Differences were highly significant (p = 0.004). CONCLUSIONS: Non-augmented Pi*ZZ and Z-patients with impaired lung function and increased liver stiffness presented higher levels of CP than other clinical phenotypes. Therefore, CP may help to identify patients more at risk of developing lung and liver disease and may provide some insight into the mechanisms of disease.

A Prospective Cohort Study of Bioavailable 25-Hydroxyvitamin D Levels as a Marker of Vitamin D Status in Nontuberculous Mycobacterial Pulmonary Disease.

Research on vitamin D in patients with nontuberculous mycobacterial (NTM) pulmonary disease (PD) is limited. We aimed to compare the vitamin D parameters of patients with NTM-PD to those of a healthy control group, and to assess the possible predictive markers for a clinical response. We prospectively enrolled 53 patients with NTM-PD between January 2014 and December 2016. The clinical data and vitamin D indices, including total, free, bioavailable 25-(OH)D, and vitamin D binding protein (VDBP) genotyping, were measured at baseline and six months after enrollment. An external dataset of 226 healthy controls was compared with the NTM-PD group. The mean age of subjects was 53 years; 54.5% were male. The NTM-PD group was older, predominantly female, and had a lower body mass index (BMI) than the controls. The proportion of patients with vitamin D concentration <50 nmol/L was 52.8% in the NTM-PD group and 54.9% in the control group (p = 0.789). The bioavailable 25-(OH)D concentrations of the NTM-PD group and the controls were similar (6.9 nmol/L vs. 7.6 nmol/L, p = 0.280). In the multivariable analysis, bioavailable 25-(OH)D concentrations were associated with NTM-PD, adjusting for age, sex, BMI, and VDBP levels. Bioavailable 25-(OH)D concentrations were significantly associated with susceptibility to NTM-PD, but not with treatment outcomes. Lower bioavailable 25-(OH)D might be a risk factor for NTM-PD.

Splenic Infarcts and Pulmonary Renal Syndrome in a Young Patient with Double-Positive Anti-GBM and ANCA-Associated Vasculitis.

Double-positive disease, defined by double-seropositivity for serum anti-glomerular basement membrane (GBM) antibodies and anti-neutrophil cytoplasmic antibodies (ANCA) is a rare cause of pulmonary-renal syndrome. Here, we present an exceptional course of a 20-year-old male with seropositivity for anti-myeloperoxidase anti-neutrophil cytoplasmic antibodies and anti-GBM antibody, who presented first with renal impairment due to focal necrotizing crescentic glomerulonephritis. After receiving treatment, he presented two years later with a relapse manifesting with diffuse alveolar hemorrhage and multiple splenic infarcts. We discuss the clinical presentation patterns and treatment strategies of this entity.

Myxomavirus serpin alters macrophage function and prevents diffuse alveolar hemorrhage in pristane-induced lupus.

C57BL/6 mice with pristane-induced lupus develop macrophage-dependent diffuse alveolar hemorrhage (DAH), which is blocked by treatment with liver X receptor (LXR) agonists and is exacerbated by low IL-10 levels. Serp-1, a myxomavirus-encoded serpin that impairs macrophage activation and plasminogen activation, blocks DAH caused by MHV68 infection. We investigated whether Serp-1 also could block DAH in pristane-induced lupus. Pristane-induced DAH was prevented by treatment with recombinant Serp-1 and macrophages from Serp1-treated mice exhibited an anti-inflammatory M2-like phenotype. Therapy activated LXR, promoting M2 polarization and expression of Kruppel-like factor-4 (KLH4), which upregulates IL-10. In contrast, deficiency of tissue plasminogen activator or plasminogen activator inhibitor had little effect on DAH. We conclude that Serp-1 blocks pristane-induced lung hemorrhage by enhancing LXR-regulated M2 macrophage polarization and KLH4-regulated IL-10 production. In view of the similarities between DAH in pristane-treated mice and SLE patients, Serp-1 may represent a potential new therapy for this severe complication of SLE.

Validation of the Withings ScanWatch as a Wrist-Worn Reflective Pulse Oximeter: Prospective Interventional Clinical Study.

BACKGROUND: A decrease in the level of pulse oxygen saturation as measured by pulse oximetry (SpO2) is an indicator of hypoxemia that may occur in various respiratory diseases, such as chronic obstructive pulmonary disease (COPD), sleep apnea syndrome, and COVID-19. Currently, no mass-market wrist-worn SpO2 monitor meets the medical standards for pulse oximeters. OBJECTIVE: The main objective of this monocentric and prospective clinical study with single-blind analysis was to test and validate the accuracy of the reflective pulse oximeter function of the Withings ScanWatch to measure SpO2 levels at different stages of hypoxia. The secondary objective was to confirm the safety of this device when used as intended. METHODS: To achieve these objectives, we included 14 healthy participants aged 23-39 years in the study, and we induced several stable plateaus of arterial oxygen saturation (SaO2) ranging from 100%-70% to mimic nonhypoxic conditions and then mild, moderate, and severe hypoxic conditions. We measured the SpO2 level with a Withings ScanWatch on each participant's wrist and the SaO2 from blood samples with a co-oximeter, the ABL90 hemoximeter (Radiometer Medical ApS). RESULTS: After removal of the inconclusive measurements, we obtained 275 and 244 conclusive measurements with the two ScanWatches on the participants' right and left wrists, respectively, evenly distributed among the 3 predetermined SpO2 groups: SpO2≤80%, 80%

Clinical Utility of Midregional Proadrenomedullin in Patients with COVID-19.

OBJECTIVE: The aim of the study was to assess the role of midregional proadrenomedullin (MR-proADM) in patients with COVID-19. METHODS: We included 110 patients hospitalized for COVID-19. Biochemical biomarkers, including MR-proADM, were measured at admission. The association of plasma MR-proADM levels with COVID-19 severity, defined as a requirement for mechanical ventilation or in-hospital mortality, was evaluated. RESULTS: Patients showed increased levels of MR-proADM. In addition, MR-proADM was higher in patients who died during hospitalization than in patients who survived (median, 2.59 nmol/L; interquartile range, 2.3-2.95 vs median, 0.82 nmol/L; interquartile range, 0.57-1.03; P <.0001). Receiver operating characteristic curve analysis showed good accuracy of MR-proADM for predicting mortality. A MR-proADM value of 1.73 nmol/L was established as the best cutoff value, with 90% sensitivity and 95% specificity (P <.0001). CONCLUSION: We found that MR-proADM could represent a prognostic biomarker of COVID-19.

Pathogenesis of Pulmonary Hemorrhagic Syndrome in Human Leptospirosis.

Based on a previous study and by incorporating new knowledge, the goal of our study was to understand more fully the pathogenesis of hemorrhagic pneumonia of severe human leptospirosis, highlighting the onset of capillary lesions by Leptospira itself and/or its antigenic/toxic products acting on the endothelium and binding to cadherins. Both events lead to loss of endothelial integrity, alter permeability, cause rupture, and open intercellular junctions, contributing to the hemorrhagic phenomena associated with severe leptospirosis.

Epigenome-wide association study of whole blood gene expression in Framingham Heart Study participants provides molecular insight into the potential role of CHRNA5 in cigarette smoking-related lung diseases.

BACKGROUND: DNA methylation is a key epigenetic modification that can directly affect gene regulation. DNA methylation is highly influenced by environmental factors such as cigarette smoking, which is causally related to chronic obstructive pulmonary disease (COPD) and lung cancer. To date, there have been few large-scale, combined analyses of DNA methylation and gene expression and their interrelations with lung diseases. RESULTS: We performed an epigenome-wide association study of whole blood gene expression in ~ 6000 individuals from four cohorts. We discovered and replicated numerous CpGs associated with the expression of cis genes within 500 kb of each CpG, with 148 to 1,741 cis CpG-transcript pairs identified across cohorts. We found that the closer a CpG resided to a transcription start site, the larger its effect size, and that 36% of cis CpG-transcript pairs share the same causal genetic variant. Mendelian randomization analyses revealed that hypomethylation and lower expression of CHRNA5, which encodes a smoking-related nicotinic receptor, are causally linked to increased risk of COPD and lung cancer. This putatively causal relationship was further validated in lung tissue data. CONCLUSIONS: Our results provide a large and comprehensive association study of whole blood DNA methylation with gene expression. Expression platform differences rather than population differences are critical to the replication of cis CpG-transcript pairs. The low reproducibility of trans CpG-transcript pairs suggests that DNA methylation regulates nearby rather than remote gene expression. The putatively causal roles of methylation and expression of CHRNA5 in relation to COPD and lung cancer provide evidence for a mechanistic link between patterns of smoking-related epigenetic variation and lung diseases, and highlight potential therapeutic targets for lung diseases and smoking cessation.

Direct and indirect evidence of efficacy and safety of rapid exercise tests for exertional desaturation in Covid-19: a rapid systematic review.

BACKGROUND: Even when resting pulse oximetry is normal in the patient with acute Covid-19, hypoxia can manifest on exertion. We summarise the literature on the performance of different rapid tests for exertional desaturation and draw on this evidence base to provide guidance in the context of acute Covid-19. MAIN RESEARCH QUESTIONS: 1. What exercise tests have been used to assess exertional hypoxia at home or in an ambulatory setting in the context of Covid-19 and to what extent have they been validated? 2. What exercise tests have been used to assess exertional hypoxia in other lung conditions, to what extent have they been validated and what is the applicability of these studies to acute Covid-19? METHOD: AMED, CINAHL, EMBASE MEDLINE, Cochrane and PubMed using LitCovid, Scholar and Google databases were searched to September 2020. Studies where participants had Covid-19 or another lung disease and underwent any form of exercise test which was compared to a reference standard were eligible. Risk of bias was assessed using QUADAS 2. A protocol for the review was published on the Medrxiv database. RESULTS: Of 47 relevant papers, 15 were empirical studies, of which 11 described an attempt to validate one or more exercise desaturation tests in lung diseases other than Covid-19. In all but one of these, methodological quality was poor or impossible to fully assess. None had been designed as a formal validation study (most used simple tests of correlation). Only one validation study (comparing a 1-min sit-to-stand test [1MSTST] with reference to the 6-min walk test [6MWT] in 107 patients with interstitial lung disease) contained sufficient raw data for us to calculate the sensitivity (88%), specificity (81%) and positive and negative predictive value (79% and 89% respectively) of the 1MSTST. The other 4 empirical studies included two predictive studies on patients with Covid-19, and two on HIV-positive patients with suspected pneumocystis pneumonia. We found no studies on the 40-step walk test (a less demanding test that is widely used in clinical practice to assess Covid-19 patients). Heterogeneity of study design precluded meta-analysis. DISCUSSION: Exertional desaturation tests have not yet been validated in patients with (or suspected of having) Covid-19. A stronger evidence base exists for the diagnostic accuracy of the 1MSTST in chronic long-term pulmonary disease; the relative intensity of this test may raise safety concerns in remote consultations or unstable patients. The less strenuous 40-step walk test should be urgently evaluated.

sFasL-The Key to a Riddle: Immune Responses in Aging Lung and Disease.

By dint of the aging population and further deepened with the Covid-19 pandemic, lung disease has turned out to be a major cause of worldwide morbidity and mortality. The condition is exacerbated when the immune system further attacks the healthy, rather than the diseased, tissue within the lung. Governed by unremittingly proliferating mesenchymal cells and increased collagen deposition, if inflammation persists, as frequently occurs in aging lungs, the tissue develops tumors and/or turns into scars (fibrosis), with limited regenerative capacity and organ failure. Fas ligand (FasL, a ligand of the Fas cell death receptor) is a key factor in the regulation of these processes. FasL is primarily found in two forms: full length (membrane, or mFasL) and cleaved (soluble, or sFasL). We and others found that T-cells expressing the mFasL retain autoimmune surveillance that controls mesenchymal, as well as tumor cell accumulation following an inflammatory response. However, mesenchymal cells from fibrotic lungs, tumor cells, or cells from immune-privileged sites, resist FasL+ T-cell-induced cell death. The mechanisms involved are a counterattack of immune cells by FasL, by releasing a soluble form of FasL that competes with the membrane version, and inhibits their cell death, promoting cell survival. This review focuses on understanding the previously unrecognized role of FasL, and in particular its soluble form, sFasL, in the serum of aged subjects, and its association with the evolution of lung disease, paving the way to new methods of diagnosis and treatment.