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INTRODUCTION: The presence of emphysema is common in patients with interstitial lung disease (ILD), which is designated as combined pulmonary fibrosis and emphysema (CPFE). This study aimed to examine the association between smoking, emphysema, and fibrosis in ILD patients. METHODS: A total of 800 patients hospitalized for ILD at the affiliated hospital of Qingdao University, Shandong, Qingdao, China, from December 2012 to December 2020 were included in our retrospective cohort study. Participants were divided into CPFE and non-CPFE groups. The patients' clinical presentations and radiographic and laboratory findings were reviewed and compared. The two groups were then divided and compared based on smoking status. Kaplan-Meier survival analysis with log-rank testing and multivariable Cox proportional hazards regression analysis were used to compare all-cause mortality. RESULTS: Emphysema was present in 188 (23.5%) ILD patients. Smoking was associated with increased odds of CPFE (adjusted odds ratio, AOR=2.13; 95% CI: 1.33-3.41, p=0.002). The CPFE patients had a comparable risk of death to non-CPFE patients (adjusted hazard ratio, AHR=0.89; 95% CI: 0.64-1.24, p=0.493). Smoking was not a risk prognostic factor in the whole group (AHR=1.34; 95% CI: 0.90-1.99, p=0.152) or the CPFE group (AHR=0.90; 95% CI: 0.43-1.86, p=0.771). However, a significant prognostic difference between smokers and non-smokers was found in the non-CPFE group (AHR=1.62; 95% CI: 1.02-2.58, p=0.042). In ILD patients, smoking pack-years were weakly correlated with total centrilobular emphysema (CLE) scores and total fibrosis scores (TFS), but not with total emphysema scores (TES); TFS were weakly correlated with TES. CONCLUSIONS: CPFE did not affect the prognosis of ILD. Smoking was a risk but not a prognostic factor for CPFE. However, smoking was associated with worse survival in non-CPFE patients. There was an intricate association among smoking, emphysema, and fibrosis in ILD patients.
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Background: Myeloid-derived suppressor cells (MDSCs) have crucial immunosuppressive role in T cell dysfunction in various disease processes. However, the role of MDSCs and their impact on Tregs in COPD have not been fully understood. The aim of the present study is to investigate the immunomodulatory role of MDSCs and their potential impact on the expansion and function of Tregs in COPD patients. Methods: Peripheral blood samples were collected to analyze circulating MDSCs, Tregs, PD-1/PD-L1 expression to assess the immunomodulatory role of MDSC and their potential impact on the expansion and function of Treg in COPD. A total of 54 COPD patients and 24 healthy individuals were enrolled in our study. Flow cytometric analyses were performed to identify granulocytic MDSCs (G-MDSCs), monocytic MDSCs (M-MDSCs), Tregs, and the expression of PD-1/PD-L1(L2) on MDSCs and Tregs in peripheral blood. Results: Our results revealed a significantly higher percentage of G-MDSCs and M-MDSCs (p < 0.001) in COPD patients compared to the healthy controls. Additionally, a significantly higher proportion of peripheral blood Tregs was observed in COPD patients. Furthermore, an increased expression of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) on Tregs (p < 0.01) was detected in COPD patients. The expression of PD-1 on CD4+ Tcells and Tregs, but not CD8+Tcells, was found to be increased in patients with COPD compared to controls. Furthermore, an elevated expression of PD-L1 on M-MDSCs (p < 0.01) was also observed in COPD patients. A positive correlation was observed between the accumulation of M-MDSCs and Tregs in COPD patients. Additionally, the percentage of circulating M-MDSCs is positively associated with the level of PD-1 (r = 0.51, p < 0.0001) and CTLA-4 (r = 0.42, p = 0.0014) on Tregs in COPD. Conclusion: The recruitment of MDSCs, accumulation of Tregs, and up-regulation of CTLA-4 on Treg in COPD, accompanied by an increased level of PD-1/PD-L1, suggest PD-1/PD-L1 axis may be potentially involved in MDSCs-induced the expansion and activation of Treg at least partially in COPD.
