Cardiopulmonary Complications after Pulmonary Embolism in COVID-19.

Although pulmonary embolism (PE) is a frequent complication in COVID-19, its consequences remain unknown. We performed pulmonary function tests, echocardiography and computed tomography pulmonary angiography and identified blood biomarkers in a cohort of consecutive hospitalized COVID-19 patients with pneumonia to describe and compare medium-term outcomes according to the presence of PE, as well as to explore their potential predictors. A total of 141 patients (56 with PE) were followed up during a median of 6 months. Post-COVID-19 radiological lung abnormalities (PCRLA) and impaired diffusing capacity for carbon monoxide (DLCOc) were found in 55.2% and 67.6% cases, respectively. A total of 7.3% had PE, and 6.7% presented an intermediate-high probability of pulmonary hypertension. No significant difference was found between PE and non-PE patients. Univariate analysis showed that age > 65, some clinical severity factors, surfactant protein-D, baseline C-reactive protein, and both peak red cell distribution width and Interleukin (IL)-10 were associated with DLCOc < 80%. A score for PCRLA prediction including age > 65, minimum lymphocyte count, and IL-1ß concentration on admission was constructed with excellent overall performance. In conclusion, reduced DLCOc and PCRLA were common in COVID-19 patients after hospital discharge, but PE did not increase the risk. A PCRLA predictive score was developed, which needs further validation.

Pulmonary thrombosis associated with COVID-19 pneumonia: Beyond classical pulmonary thromboembolism.

BACKGROUND: Classical pulmonary thromboembolism (TE) and local pulmonary thrombosis (PT) have been suggested as mechanisms of thrombosis in COVID-19. However, robust evidence is still lacking because this was mainly based on retrospective studies, in which patients were included when TE was suspected. METHODS: All patients with COVID-19 pneumonia underwent computed tomography and pulmonary angiography in a prospective study. The main objective was to determine the number and percentage of thrombi surrounded by lung opacification (TSO) in each patient, as well as their relationship with percentage of lung involvement (TLI), to distinguish classical TE (with a random location of thrombi that should correspond to a percentage of TSO equivalent to the TLI) from PT. We determined TLI by artificial intelligence. Analyses at patient level (TLI and percentage of TSO) and at thrombi level (TLI and TSO) were performed. RESULTS: We diagnosed TE in 70 out of 184 patients. Three (2-8) thrombi/patient were detected. The percentage of TSO was 100% (75-100) per patient, and TLI was 19.9% (4.6-35.2). Sixty-five patients (92.9%) were above the random scenario with higher percentage of TSO than TLI. Most thrombi were TSO (n = 299, 75.1%). When evaluating by TLI (<10%, 10%-20%, 20%-30% and >30%), percentage of TSO was higher in most groups. Thrombi were mainly in subsegmental/segmental arteries, and percentage of TSO was higher in all locations. CONCLUSIONS: Thrombi in COVID-19 were found within lung opacities in a higher percentage than lung involvement, regardless of TLI and clot location, supporting the hypothesis of local PT rather than "classic TE".

A Prospective Study Evaluating Cumulative Incidence and a Specific Prediction Rule in Pulmonary Embolism in COVID-19.

Rationale: Abnormal values of hypercoagulability biomarkers, such as D-dimer, have been described in Coronavirus Disease 2019 (COVID-19), which has also been associated with disease severity and in-hospital mortality. COVID-19 patients with pneumonia are at greater risk of pulmonary embolism (PE). However, the real incidence of PE is not yet clear, since studies have been limited in size, mostly retrospective, and PE diagnostic procedures were only performed when PE was clinically suspected. Objectives: (1) To determine the incidence, clinical, radiological, and biological characteristics, and clinical outcomes of PE among patients hospitalized for COVID-19 pneumonia with D-dimer > 1,000 ng/mL. (2) To develop a prognostic model to predict PE in these patients. Methods: Single-center prospective cohort study. Consecutive confirmed cases of COVID-19 pneumonia with D-dimer > 1,000 ng/mL underwent computed tomography pulmonary angiography (CTPA). Demographic and laboratory data, comorbidities, CTPA scores, treatments administered, and clinical outcomes were analyzed and compared between patients with and without PE. A risk score was constructed from all these variables. Results: Between 6 April 2020 and 2 February 2021, 179 consecutive patients were included. The overall incidence of PE was 39.7% (71 patients) (CI 95%, 32-47%). In patients with PE, emboli were located mainly in segmental/subsegmental arteries (67%). Patients with PE did not differ from the non-PE group in sex, age, or risk factors for thromboembolic disease. Higher urea, D-Dimer, D-dimer-to-ferritin and D-dimer-to-lactate dehydrogenase (LDH) ratios, platelet distribution width (PDW), and neutrophil-to-lymphocyte ratio (NLR) values were found in patients with PE when compared to patients with non-PE. Besides, lymphocyte counts turned out to be lower in patients with PE. A score for PE prediction was constructed with excellent overall performance [area under the ROC curve-receiver operating characteristic (AUC-ROC) 0.81 (95% CI: 0.73-0.89)]. The PATCOM score stands for Pulmonary Artery Thrombosis in COVID-19 Mallorca and includes platelet count, PDW, urea concentration, and D-dimer-to-ferritin ratio. Conclusion: COVID-19 patients with pneumonia and D-dimer values > 1,000 ng/mL were presented with a very high incidence of PE, regardless of clinical suspicion. Significant differences in urea, D-dimer, PDW, NLR, and lymphocyte count were found between patients with PE and non-PE. The PATCOM score is presented in this study as a promising PE prediction rule, although validation in further studies is required.

TLR/WNT: A Novel Relationship in Immunomodulation of Lung Cancer.

The most frequent cause of death by cancer worldwide is lung cancer, and the 5-year survival rate is still very poor for patients with advanced stage. Understanding the crosstalk between the signaling pathways that are involved in disease, especially in metastasis, is crucial to developing new targeted therapies. Toll-like receptors (TLRs) are master regulators of the immune responses, and their dysregulation in lung cancer is linked to immune escape and promotes tumor malignancy by facilitating angiogenesis and proliferation. On the other hand, over-activation of the WNT signaling pathway has been reported in lung cancer and is also associated with tumor metastasis via induction of Epithelial-to-mesenchymal-transition (EMT)-like processes. An interaction between both TLRs and the WNT pathway was discovered recently as it was found that the TLR pathway can be activated by WNT ligands in the tumor microenvironment; however, the implications of such interactions in the context of lung cancer have not been discussed yet. Here, we offer an overview of the interaction of TLR-WNT in the lung and its potential implications and role in the oncogenic process.

Hsa-Mir-320c, Hsa-Mir-200c-3p, and Hsa-Mir-449c-5p as Potential Specific miRNA Biomarkers of COPD: A Pilot Study.

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease commonly induced by cigarette smoke. The expression of miRNAs can be altered in patients with COPD and could be used as a biomarker. We aimed to identify a panel of miRNAs in bronchoalveolar lavage (BAL) to differentiate COPD patients from smokers and non-smokers with normal lung function. Accordingly, forty-five subjects classified as COPD, smokers, and non-smokers (n = 15 per group) underwent clinical, functional characterization and bronchoscopy with BAL. The mean age of the studied population was 61.61 ± 12.95 years, BMI 25.72 ± 3.82 Kg/m2, FEV1/FVC 68.37 ± 12.00%, and FEV1 80.07 ± 23.63% predicted. According to microarray analysis, three miRNAs of the most upregulated were chosen: miR-320c, miR-200c-3p, and miR-449c-5p. These miRNAs were validated by qPCR and were shown to be differently expressed in COPD patients. ROC analysis showed that these three miRNAs together had an area under the curve of 0.89 in differentiating COPD from controls. Moreover, in silico analysis of candidate miRNAs by DIANA-miRPath showed potential involvement in the EGFR and Hippo pathways. These results suggest a specific 3-miRNA signature that could be potentially used as a biomarker to distinguish COPD patients from smokers and non-smoker subjects.

Different Faces of Idiopathic Pulmonary Fibrosis With Preserved Forced Vital Capacity.

INTRODUCTION: Idiopathic pulmonary fibrosis (IPF) is progressive and irreversible. Some discrepancies about IPF staging exists, especially in mild phases. Forced vital capacity (FVC) higher than 80% has been considered early or mild IPF even for the design of clinical trials. METHODS: Spanish multicentre, observational, retrospective study of IPF patients diagnosed between 2012 and 2016, based on the ATS/ERS criteria, which presented FVC greater or equal 80% at diagnosis. Clinical and demographic characteristics, lung function, radiological pattern, treatment, and follow-up were analyzed. RESULTS: 225 IPF patients were included, 72.9% were men. The mean age was 69.5 years. The predominant high-resolution computed tomography (HRCT) pattern was consistent usual interstitial pneumonia (UIP) (51.6%). 84.7% of patients presented respiratory symptoms (exertional dyspnea and/or cough) and 33.33% showed oxygen desaturation below 90% in the 6min walking test (6MWT). Anti-fibrotic treatment was initiated at diagnosis in 55.11% of patients. Median FVC was 89.6% (IQR 17) and 58.7% of patients had a decrease of diffusion lung capacity for carbon monoxide (DLCO) below 60% of theoretical value; most of them presented functional progression (61.4%) and higher mortality at 3 years (20.45%). A statistically significant correlation with the 3-years mortality was observed between DLCO <60% and consistent UIP radiological pattern. CONCLUSIONS: Patients with preserved FVC but presenting UIP radiological pattern and moderate-severe DLCO decrease at diagnosis associate an increased risk of progression, death or lung transplantation. Therefore, in these cases, preserved FVC would not be representative of early or mild IPF.

Prevalence of pulmonary embolism in patients with COVID-19 pneumonia and high D-dimer values: A prospective study.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) pneumonia is associated to systemic hyper-inflammation and abnormal coagulation profile. D-dimer elevation is particularly frequent, and values higher than 1µg/mL have been associated with disease severity and in-hospital mortality. Previous retrospective studies found a high pulmonary embolism (PE) prevalence, however, it should be highlighted that diagnoses were only completed when PE was clinically suspected. MATERIAL AND METHODS: Single-center prospective cohort study. Between April 6th and April 17th 2020, consecutive confirmed cases of COVID-19 pneumonia with D-dimer >1 µg/mL underwent computed tomography pulmonary angiography (CTPA) to investigate the presence and magnitude of PE. Demographic and laboratory data, comorbidities, CTPA scores, administered treatments, and, clinical outcomes were analysed and compared between patients with and without PE. RESULTS: Thirty consecutive patients (11 women) were included. PE was diagnosed in 15 patients (50%). In patients with PE, emboli were located mainly in segmental arteries (86%) and bilaterally (60%). Patients with PE were significantly older (median age 67.0 (IQR 63.0-73.0) vs. 57.0 (IQR 48.0-69.0) years, p = .048) and did not differ in sex or risk factors for thromboembolic disease from the non-PE group. D-dimer, platelet count, and, C reactive protein values were significantly higher among PE patients. D-dimer values correlated with the radiologic magnitude of PE (p<0.001). CONCLUSIONS: Patients with COVID-19 pneumonia and D-dimer values higher than 1 µg/mL presented a high prevalence of PE, regardless of clinical suspicion. We consider that these findings could contribute to improve the prognosis of patients with COVID-19 pneumonia, by initiating anticoagulant therapy when a PE is found.

Colchicine Administered in the First Episode of Acute Idiopathic Pericarditis: A Randomized Multicenter Open-label Study.

INTRODUCTION AND OBJECTIVES: There is a paucity of information about the real benefit of colchicine administration in the first episode of acute idiopathic pericarditis (AIP). The main objective of the present study was to assess the real efficacy of colchicine in patients with AIP who did not receive corticosteroids. METHODS: Randomized multicenter open-label study. Patients with a first episode of AIP (not secondary to cardiac injury or connective tissue disease) were randomized into 2 groups: group A received conventional anti-inflammatory treatment plus colchicine for 3 months, and group B received conventional anti-inflammatory treatment only. None of the patients received corticosteroids. The primary endpoint was the appearance of recurrent episodes of pericarditis. The secondary endpoint was the time to first recurrence. Follow-up was extended to 24 months. RESULTS: A total of 110 patients (83.6% men, age 44±18.3 years) were randomized to group A (n=59) and group B (n=51). No differences were found in baseline demographics or in the clinical features of the index episode or in the type of anti-inflammatory treatment administered in both groups. The follow-up was completed by 102 patients (92.7%). No differences were found in the rate of recurrent pericarditis between groups (12 patients [10.9%]; group A vs group B, 13.5% vs 7.8%; P=.34). The time to first recurrence (group A vs group B, 9.6±9.0 vs 8.3±10.5 months; P=.80) did not differ between groups. CONCLUSIONS: Among patients with a first episode of AIP who had not received corticosteroids, the addition of colchicine to conventional anti-inflammatory treatment does not seem to reduce the recurrence rate. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrialsregister.eu. Identifier: EudraCT 2009-011258-16.

Physical Activity Is Associated with Attenuated Disease Progression in Chronic Obstructive Pulmonary Disease.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) progression is variable and affects several disease domains, including decline in lung function, exercise capacity, muscle strength, and health status as well as changes in body composition. We aimed to assess the longitudinal association of physical activity (PA) with these a priori selected components of disease progression. METHODS: We studied 114 COPD patients from the PAC-COPD cohort (94% male, mean [SD], 70 yr [8 yr] of age, 54 [16] forced expiratory volume in 1 s % predicted) at baseline and 2.6 yr (0.6 yr) later. Baseline PA was assessed by accelerometry. Multivariable general linear models were built to assess the association between PA and changes in lung function, functional exercise capacity, muscle strength, health status, and body composition. All models were adjusted for confounders and the respective baseline value of each measure. RESULTS: Per each 1000 steps higher baseline PA, forced expiratory volume in 1 s declined 7 mL less (P < 0.01), forced vital capacity 9 mL less (P = 0.03) and carbon monoxide diffusing capacity 0.10 mL·min·mm Hg less (P = 0.04), while the St George's Respiratory Questionnaire symptom domain deteriorated 0.4 points less (P = 0.03), per year follow-up. Physical activity was not associated with changes in functional exercise capacity, muscle strength, other domains of health status or body composition. CONCLUSIONS: Higher PA is associated with attenuated decline in lung function and reduced health status (symptoms domain) deterioration in moderate-to-very severe COPD patients.

Idiopathic Pulmonary Fibrosis: Epidemiology, Natural History, Phenotypes.

Idiopathic pulmonary fibrosis (IPF) is the most common of the idiopathic interstitial pneumonias. It is characterized by a chronic, progressive, fibrotic interstitial lung disease of unknown cause that occurs primarily in older adults. Its prevalence and incidence have appeared to be increasing over the last decades. Despite its unknown nature, several genetic and environmental factors have been associated with IPF. Moreover, its natural history is variable, but could change depending on the currently suggested phenotypes: rapidly progressive IPF, familial, combined pulmonary fibrosis and emphysema, pulmonary hypertension, and that associated with connective tissue diseases. Early recognition and accurate staging are likely to improve outcomes and induce a prompt initiation of antifibrotics therapy. Treatment is expected to be more effective in the early stages of the disease, while developments in treatment aim to improve the current median survival of 3⁻4 years after diagnosis.

Usefulness of Bronchoscopic Probe-Based Confocal Laser Endomicroscopy in the Diagnosis of Pneumocystis jirovecii Pneumonia.

BACKGROUND: Probe-based confocal laser endomicroscopy (pCLE) is a novel technique that provides in vivo microscopic imaging of the distal lung. We hypothesized that the intra-alveolar exudates characterizing Pneumocystis jirovecii pneumonia (PJP) can be identified by pCLE in vivo and help in its diagnosis. OBJECTIVES: We aimed to assess the usefulness of pCLE for the in vivo diagnosis of PJP. METHODS: Thirty-two human immunodeficiency virus (HIV)-positive patients with new pulmonary infiltrates and fever were studied using pCLE. Real-time alveolar images were recorded during the bronchoscopy for off-line analysis by two independent observers. Bronchoalveolar lavage samples were also obtained and processed for microbiology and cytological evaluation, including Grocott stain for P. jirovecii. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of pCLE for the diagnosis of PJP in these patients were calculated. RESULTS: Fourteen patients (44%) were confirmed to have PJP by cultures/staining. pCLE was well tolerated in all patients. It identified intra-alveolar exudates in 13 of them (41%), where 11 of them (85%) had positive Grocott stain for P. jirovecci, with 93% concordance between observers. Sensitivity, specificity, PPV and NPV of pCLE for the diagnosis of PJP were 79, 89, 85 and 84%, respectively. In smokers, these figures improved to be 92, 88, 85 and 94%. CONCLUSIONS: pCLE is a quick and safe procedure for on-site diagnosis of PJP in HIV+ patients with excellent specificity and sensitivity mainly in smokers.

Risk of postoperative complications in chronic obstructive lung diseases patients considered fit for lung cancer surgery: beyond oxygen consumption.

OBJECTIVES: Patients with poor lung function usually undergo cardiopulmonary exercise testing (CPET) and those with a predicted postoperative maximal oxygen consumption (VO2 max) of >10 ml/kg/min undergo lung resection surgery and still some complications are observed. We aimed to determine other parameters beyond VO2 able to predict postoperative complications in patients undergoing lung resection surgery. METHODS: This is an observational study with longitudinal follow-up. Patients with forced expiratory volume in 1 second (FEV1) or diffusing capacity for carbon monoxide of <40% underwent CPET and those with VO2 max of >10 ml/kg/min were considered fit for surgery. Patients were followed up prospectively for 12 months and postoperative complications and survival were recorded. Physiological parameters obtained during CPET and pulmonary function tests were analysed. RESULTS: Eighty-three chronic obstructive pulmonary disease (COPD) patients were evaluated for surgery between 2010 and 2015. Twenty-four patients were considered unfit for surgery and received an alternative therapy. Fifty-five patients had a VO2 max of >10 ml/kg/min and underwent lung surgery. Among them, 4% died and 41% developed complications postoperatively. Baseline minute ventilation to carbon dioxide output (VE/VCO2) slope was significantly higher among those who developed postoperative complications or died (P = 0.047). Furthermore, VE/VCO2 slope of >35 (at maximal exercise) was the single parameter most strongly associated with the probability of mortality and postoperative complications (hazard ratio 5.14) with a survival probability of 40% after 1 year of follow-up. In a multivariable model, VO2, VE/VCO2 slope of >35 and work load were independently associated with the probability of having an event. CONCLUSIONS: VO2 is not the unique parameter to consider when CPET is performed to evaluate the postoperative risk of lung cancer surgery in COPD patients. The signs of ventilatory inefficiency such as VE/VCO2 slope predict complications better than VO2 does.

Lack of Correlation Between Pulmonary and Systemic Inflammation Markers in Patients with Chronic Obstructive Pulmonary Disease: A Simultaneous, Two-Compartmental Analysis. / Ausencia de correlación entre marcadores de inflamación pulmonar y sistémica en pacientes con enfermedad pulmonar obstructiva crónica: un análisis bi-compartimental simultáneo.

INTRODUCTION: The origin of systemic inflammation in chronic obstructive pulmonary disease (COPD) patients remains to be defined, but one of the most widely accepted hypothesis is the 'spill over' of inflammatory mediators from the lung to the circulation. OBJECTIVE: To evaluate the relationship between pulmonary and systemic inflammation in COPD quantifying several inflammatory markers in sputum and serum determined simultaneously. METHODOLOGY: Correlations between various inflammatory variables (TNF-α, IL6, IL8) in sputum and serum were evaluated in 133 patients from the PAC-COPD cohort study. A secondary objective was the evaluation of relationships between inflammatory variables and lung function. RESULTS: Inflammatory markers were clearly higher in sputum than in serum. No significant correlation was found (absolute value, r=0.03-0.24) between inflammatory markers in blood and in sputum. There were no significant associations identified between those markers and lung function variables, such as FEV1, DLCO and PaO2 neither. CONCLUSIONS: We found no correlation between pulmonary and systemic inflammation in patients with stable COPD, suggesting different pathogenic mechanisms.

Prevalence and Perception of 24-Hour Symptom Patterns in Patients With Stable Chronic Obstructive Pulmonary Disease in Spain. / Prevalencia y percepción de la variabilidad diaria de los síntomas en pacientes con enfermedad pulmonar obstructiva crónica estable en España.

INTRODUCTION: Few studies have examined the 24-hour symptom profile in patients with chronic obstructive pulmonary disease (COPD). The main objective of this study was to determine daily variations in the symptoms of patients with stable COPD in Spain, compared with other European countries. METHODS: Observational study conducted in 8 European countries. The results from the Spanish cohort (n=122) are compared with the other European subjects (n=605). We included patients with COPD whose treatment had been unchanged in the previous 3months. Patients completed questionnaires on morning, day-time, and night-time symptoms of COPD, the COPD assessment test (CAT), the hospital anxiety and depression scale (HADS), and the COPD and asthma sleep impact scale (CASIS). RESULTS: Mean age: 69 (standard deviation [SD]=9) years; mean post-bronchodilator FEV1: 50.5 (SD=19.4)% (similar in Spanish and European cohorts). The proportion of men among the Spanish cohort was greater (91.0% versus 60.7%, P<.0001). A total of 52.5% patients experienced some type of symptom throughout the day, compared to 57.5% of the other Europeans, P<.001). Patients with symptoms throughout the day had poorer health-related quality of life (HRQoL) and higher levels of anxiety/depression than patients without symptoms. Patients with night-time symptoms had a poorer quality of sleep. Spanish patients with symptoms throughout the day had higher CAT scores (16.9 versus 20.5 in the other Europeans, P<.05). CONCLUSIONS: Despite receiving treatment, more than half of patients report symptoms throughout the day. These patients have poorer HRQoL and higher levels of anxiety/depression. Among patients with similar lung function, the Spanish cohort was less symptomatic and reported better HRQoL than other Europeans.

Inspiratory capacity-to-total lung capacity ratio and dyspnoea predict exercise capacity decline in COPD.

BACKGROUND AND OBJECTIVE: Exercise capacity decline is a predictor of mortality in patients with chronic obstructive pulmonary disease (COPD). Static pulmonary hyperinflation is a key determinant of exercise performance, but its effect on the longitudinal decline in exercise capacity remains unknown. We aimed to study the relationship between the inspiratory capacity-to-total lung capacity (IC/TLC) ratio and exercise capacity decline in COPD. METHODS: We measured IC/TLC and other relevant clinical and functional variables in 342 clinically stable patients with COPD. The 6-min walk distance (6MWD) was determined at recruitment and after a mean ± SD of 1.7 ± 0.3 years. The annual rate of change in 6MWD was calculated. Multiple imputation to account for losses during follow up was implemented, and multivariate regression was used to analyze predictive factors of 6MWD decline. RESULTS: Mean decline rate in the 6MWD was 21.9 ± 34.1 m/year. In the bivariate analysis, patients with lower levels of IC/TLC had greater 6MWD decline (-27.4 ± 42.5, -24.9 ± 36.5 and -13.4 ± 39.9 m/year in the first, second and third tertile of IC/TLC, respectively; P-for-trend = 0.018). From other potential risk factors considered, dyspnoea, health status, serum C-reactive protein and Borg dyspnoea score at the end of the exercise test were related to exercise capacity decline. In the multivariate regression model, only IC/TLC (ß = 0.7 m/year per each percentage unit of IC/TLC; P = 0.007) and dyspnoea (mMRC ≥ 2) (ß = -14.6 m/year; P = 0.013) were associated with the annual rate of 6MWD change. CONCLUSION: IC/TLC and dyspnoea in clinically stable patients with COPD predict their exercise capacity decline and may help to guide early therapeutic interventions.

Myeloid-Derived Suppressor Cells: Possible Link Between Chronic Obstrucive Pulmonary Disease and Lung Cancer.

Chronic obstructive pulmonary disease (COPD) and lung cancer (LC) are prevalent diseases and are a leading cause of morbidity and mortality worldwide. There is strong evidence to show that COPD is an independent risk factor for LC. Chronic inflammation plays a significant pathogenic role in COPD comorbidities, particularly in LC. On the one hand, cellular and molecular inflammatory mediators promote carcinogenesis and, on the other, chronic inflammation impairs the capacity of the immune system to identify and destroy pre-malignant and malignant cells, a process known as tumor immune surveillance. This altered antitumor immunity is due in part to the expansion of myeloid-derived suppressor cells (MDSC), which are characterized by an ability to suppress the antitumor activity of T-cells by down-regulation of the T-cell receptor ζ chain (TCRζ) through the catabolism of L-arginine. COPD and LC patients share a common pattern of expansion and activation of circulating MDSC associated with TCRζ downregulation and impaired peripheral T-cell function. The objectives of this study were to review the evidence on the association between COPD and LC and to analyze how MDSC accumulation may alter tumor immune surveillance in COPD, and therefore, promote LC development.