RiteeshGrandhi/sciclaimeval-shared-task huggingface dataset:
Materials and Methods
A total of 54 stable COPD patients spirometric stages I–IV (confirmed according to the Global Initiative for Obstructive Lung Disease (GOLD)) and 24 age-matched donors with normal lung function considered controls were enrolled. COPD was defined as follows: a post-bronchodilator FEV1/FVC ratio < 0.7 and FEV1 of less than 80% of the predicted value. COPD subjects with exacerbations within the 2-month prior to the study were excluded. Other exclusion criteria included the following: cancer, asthma, heart disease, autoimmune diseases, infectious diseases and administration with immunomodulatory drugs. Ethics committee approval (No. 18190-0-01) was obtained for the trial protocol at Tsinghua Changgeng Hospital. The remaining samples obtained from the patients after testing were utilized, and as a result, the ethics committee granted a waiver of informed consent for their use (No. 18190-0-01).

Fresh peripheral blood samples were isolated from each subject and subjected to Ficoll-Paque Plus (GE Healthcare, Pittsburgh, PA, USA) layering and centrifugation (200 × 6 g for 5 min). Through Ficoll-Paque gradient centrifugation, human peripheral blood mononuclear cells were subsequently isolated.

Human PBMC were freshly obtained and stained with fluorochrome (APC, FITC, PE, PerCP-Cyanine5.5)-conjugated antibodies. For surface staining, the following antibodies were used: CD25 (cat. 12-0257-42), PD-1 (cat. 61-2799-42), PD-L2 (cat. 25-9952-42),CTLA-4 (cat. 85-46-1529-42), CD4 (cat. 25-0049-42), CD127 (cat. 17-1278-42), CD14 (cat. 61-0149-42), HLA-DR (cat. 25-9952), CD14 (cat. 61-0149-42), PD-L1 (cat. 85-12-5888-42), CD15 (cat. 11-0159-42), CD33 (cat. 56-0338-42), CD3 (cat. MHCD0327), CD11b (cat. 46-0118-42) for 30 min at 4 °C according to surface marker staining of each subpopulation and the corresponding isotype-matched controls were also used. eBioscience provided all of the antibodies we used. The gated strategies to identify Treg (CD3 + CD4 + CD25 + CD127 −/low ), G-MDSCs (CD15 + CD33 + CD11b + CD14 - HLA-DR −/low ) and M-MDSCs (CD14 + CD15 − CD11b + CD33 + HLA-DR −/low ) were shown respectively in the below section. The data in this study were acquired using CytoFLEX instrument (Beckman Coulter, Pasadena, CA, USA) and analyzed using CytExpert for DxFLEX (Beckman Coulter, Pasadena, CA, USA).

Data are expressed as the mean ± SEM. Comparisons between multiple groups were performed by variance (ANOVA) analysis, while statistical analysis was performed with Student’s t-test between two groups. An evaluation of the correlation was made using Spearman’ s rank correlation coefficient. Data were analyzed using GraphPad PRISM software (Version 8.0 for Windows; San Diego, CA, USA). Statistical significance was determined at a threshold of p < 0.05 (* for p < 0.05,** for p < 0.01, *** for p < 0.001, **** for p < 0.0001).
Conclusions
In conclusion, we observed the accumulation of circulating MDSCs subsets, immunosuppressive Tregs and upregulation expression of the PD-1/PD-L1, not PD-L2, on these two cell populations in COPD patients and we speculated that PD-1/PD-L1 axis may be involved in MDSCs, especially M-MDSCs, induced Tregs expansion and activation at least partially in COPD patients. Additionally, smoking status was inversely related to the percentage of G-MDSCs and decreased expression of PD-L1 by G-MDSCs, implying the negative effects of smoking on G-MDSCs cells production and the impaired immunosuppressive function of G-MDSCs. However, our result need more experiments in vitro and in vivo to prove. A comprehensive and in-depth understanding of MDSC subsets in COPD may help to provide useful prognostic indicators and effective therapeutic targets for the disease.
Figure 1: The frequency of MDSCs subsets in peripheral blood was significantly increased in COPD patients.
(A) The gated strategies to identify M-MDSCs; (B) Gated strategies for identifying G-MDSCs; (C and D) a higher diversity of M-MDSC percentages was observed in the peripheral blood of COPD patients compared with controls (n = 54 and 24, respectively); (E and F) the percentages of G-MDSCs in peripheral blood of COPD patients were higher than those in control (n = 54 and 24, respectively). Data were expressed as mean ± SEM, **p < 0.01; ***p < 0.001.

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DOI: 10.7717/peerj.16988/fig-1
Figure 2: The frequency of Tregs and the CTLA-4 expression on Tregs in COPD patients peripheral blood.
(A) The gated strategies for Tregs; (B and C) The increased percentage of Tregs in COPD patients peripheral blood compared with controls (n = 54 and 24, respectively); (D and E) the increased expression of CTLA-4 on Tregs in COPD patients compared with controls (n = 54 and 24, respectively). Data were expressed as mean ± SEM, *p < 0.05; **p < 0.01; ***p < 0.001.

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DOI: 10.7717/peerj.16988/fig-2
Figure 3: The abnormal expression patternof PD-L1 on MDSCs subsets and the expression of PD-1 on T cell subsets in COPD patients peripheral blood.
(A and E) The expression level of CD273 (PD-L2) on M-MDSC in COPD patients peripheral blood; (B and F) the expression level of CD274 (PD-L1) on M-MDSC in COPD patients peripheral blood; (C and G) the expression level of CD273 (PD-L2) on G-MDSC in COPD patients peripheral blood; (D and H) the expression level of CD274 (PD-L1) on G-MDSC in COPD patients peripheral blood; (I and K) the expression of PD-1 on CD4+T cells in COPD patients peripheral blood; (J and L) the expression of PD-1 on Treg in COPD patients peripheral blood; Data were expressed as mean ± SEM, *p < 0.05; **p < 0.01; ***p < 0.001. n = 54 and 24 for COPD patients (25 in stages I–II and 29 in stages III–IV) and controls respectively.

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DOI: 10.7717/peerj.16988/fig-3
Figure 4: Relationship of MDSCs subsets, Tregs and PD-1/PD-L1 expression in COPD peripheral blood.
(A and B) The percentages of M-MDSCs cells were positively correlated with the expression of PD-1 on CD4+T cells (A, r = 0.32, p = 0.001, n = 54) and CD8+T cells (B, r = 0.36, p = 0.008, n = 54); (C and D) the percentages of M-MDCS were positively correlated with the expression of PD-1 on Treg (C, r = 0.36, p = 0.008, n = 54) and CTLA-4 on Tregs (D, r = 0.42, p = 0.0014, n = 54); (E) the percentages of M-MDCS were positively correlated with the percentages of M-MDSCs and Treg cells in COPD patients (r = 0.315, p = 0.02, n = 54); (F) the percentages of G-MDSCs cells were positively related to the percentages of M-MDSCs in COPD patients (r = 0.29, p = 0.028, n = 54); (G and H) increased percentages of G-MDSCs was associated with the increased expression of PD-1 on CD4+T cells (G, r = 0.299, p = 0.028, n = 54) and Treg (H, r = 0.297, p = 0.028, n = 54) and in COPD patients; (I-K)Relationship between smoking pack-years and PD-1 expression on CD4+T cells (I), PD-1 expression on Tregs (J, r = −0.33, p = 0.04, n = 54), and percentages of G-MDSCs (K, r = −0.35, p = 0.03, n = 54) in COPD peripheral blood.

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DOI: 10.7717/peerj.16988/fig-4
Participants’ clinical characteristics and demographics.