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Introduction: The GAP model was widely used as a simple risk "screening" method for patients with idiopathic pulmonary fibrosis (IPF). Objectives: We sought to validate the GAP model in Chinese patients with IPF to evaluate whether it can accurately predict the risk for mortality. Methods: A total of 212 patients with IPF diagnosed at China‐Japan Friendship Hospital from 2015 to 2019 were enrolled. The latest follow‐up ended in September 2022. Cumulative mortality of each GAP stage was calculated and compared based on Fine‐Gray models for survival, and lung transplantation was treated as a competing risk. The performance of the model was evaluated in terms of both discrimination and calibration. Results: The cumulative mortality in patients with GAP stage III was significantly higher than that in those with GAP stage I or II (Gray's test p < 0.0001). The Harrell c‐index for the GAP calculator was 0.736 (95% CI: 0.667–0.864). The discrimination for the GAP staging system were similar with that for the GAP calculator. The GAP model overestimated the mortality rate at 1‐ and 2‐year in patients classified as GAP stage I (6.90% vs. 1.77% for 1‐year, 14.20% vs. 6.78% for 2‐year). Conclusions: Our findings indicated that the GAP model overestimated the mortality rate in mild group. [ABSTRACT FROM AUTHOR]

Background: Idiopathic pulmonary fibrosis (IPF) is a fatal disease characterized by fibroblastic foci and progressive scarring of the pulmonary parenchyma. IPF fibroblasts display increased proliferation and enhanced migration and invasion, analogous to cancer cells. This transformation-like phenotype of fibroblasts plays an important role in the development of pulmonary fibrosis, but the mechanism for this is not well understood.Methods: In this study, we compared gene expression profiles in fibrotic lung tissues from IPF patients and normal lung tissues from patients with primary spontaneous pneumothorax using a cDNA microarray to examine the mechanisms involved in the pathogenesis of IPF. In a cDNA microarray, we found that USP13 was decreased in lung tissues from patients with IPF, which was further confirmed by results from immunohistochemistry and western blot assays. Then, we used RNA interference in MRC-5 cells to inhibit USP13 and evaluated its effects by western blot, real-time RT-PCR, bromodeoxyuridine incorporation, and transwell assays. We also used co-immunoprecipitation and immunofluorescence staining to identify the correlation between USP13 and PTEN in IPF.Results: USP13 expression levels were markedly reduced in fibroblastic foci and primary IPF fibroblast lines. The depletion of USP13 resulted in the transformation of fibroblasts into an aggressive phenotype with enhanced proliferative, migratory, and invasive capacities. Additionally, USP13 interacted with PTEN and mediated PTEN ubiquitination and degradation in lung fibroblasts.Conclusions: Down-regulation of USP13 mediates PTEN protein loss and fibroblast phenotypic change, and thereby plays a crucial role in IPF pathogenesis. [ABSTRACT FROM AUTHOR]

Rationale: Sarcoidosis is a granulomatous interstitial lung disease involving a complex interplay among different cluster of differentiation 4 (CD4 + ) thymus cell (T-cell) subsets. Originally described as a type 1 T-helper (Th1) inflammatory disease, recent evidence suggests that both effector and regulatory T-cell subgroups play a critical role in sarcoidosis, but this remains controversial., Objectives: We aimed to investigate the distribution of CD4 + T-cell subpopulations in sarcoidosis patients and its potential associations with clinical disease activity and a radiographic fibrotic phenotype., Methods: We measured the frequencies of regulatory T cells (Tregs), Th1, Th17, and Th17.1 cells in the peripheral blood and/or bronchoalveolar lavage fluid (BALF) of 62 sarcoidosis patients, 66 idiopathic pulmonary fibrosis (IPF) patients, and 41 healthy volunteers using flow cytometry. We also measured the changes in these T-cell subpopulations in the blood at the follow-up visits of 11 sarcoidosis patients., Measurements and Results: An increased percentage of Tregs was observed in the peripheral blood of sarcoidosis patients, with a positive association to disease activity and a fibrotic radiographic phenotype. We found a higher frequency of Tregs, a lower proportion of Th17.1 cells, and a lower ratio of Th17.1 cells to total Tregs in the peripheral blood of both active and fibrotic sarcoidosis patients, compared with IPF patients or healthy donors. In contrast, a lower frequency of Tregs and a higher proportion of Th17.1 cells was found in the BALF of sarcoidosis patients than in that of IPF patients. There was an imbalance of Tregs and Th17.1 cells between the peripheral blood and BALF in sarcoidosis patients. Following immunoregulatory therapy, the proportion of circulating Tregs in sarcoidosis patients decreased., Conclusion: A higher proportion of Tregs in the peripheral blood of sarcoidosis patients was related to disease activity, fibrotic phenotype, and the need for immunoregulatory therapy. The imbalanced distribution of Tregs and Th17.1 cells in patients' peripheral blood and BALF suggests that the lung microenvironment has an effect on the immunological pathogenesis of sarcoidosis. Therefore, further studies on the functional analysis of Tregs and Th17.1 cells in sarcoidosis patients are warranted., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhang, Jiang, Zhu, Zhou, Xie, Cui, Costabel and Dai.)

Objective: To explore the role and underlying mechanisms of insulin-like growth factor I (IGF-I)/extracellular signal-regulated kinase (ERK) signaling pathway in lung fibrosis., Methods: Alveolar epithelial cell A549 was used. The expressions of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in A549 culture media stimulated by IGF-I were determined by enzyme-linked immunosorbent assay (ELISA). ERK inhibitor U0126 was used. And there were three groups of control, IGF-I stimulation and RK inhibitor plus IGF-I stimulation. The activity of ERK in three groups was measured by Western blot. The mRNA level and protein concentration of MMP-2 and MMP-9 in three groups were examined by quantitative real-time-polymerase chain reaction (qRT-PCR) and ELISA., Results: The protein concentrations of MMP-2 and MMP-9 in cell culture media increased in 50, 100 ng/ml IGF-I groups as compared with 0 ng/ml IGF-I group ((18.30 ± 0.11), (21.80 ± 0.09) vs (13.52 ± 0.19) ng/ml and (0.34 ± 0.01), (0.39 ± 0.01) vs (0.25 ± 0.01) ng/ml, P < 0.001). And the protein concentrations of MMP-2 and MMP-9 in 100 ng/ml IGF-I group increased versus 50 ng/ml IGF-I group (P < 0.01). IGF-I stimulation group increased the expression of p-ERK1/2 versus control group (0.40 ± 0.01 vs 0.23 ± 0.02, P < 0.05) while ERK inhibitor plus IGF-I stimulation group decreased the expression of p-ERK1/2 versus IGF-I stimulation group (0.14 ± 0.03 vs 0.40 ± 0.01, P < 0.01). ERK inhibitor plus IGF-I stimulation group inhibited the mRNA levels of MMP-2 and MMP-9 versus IGF-I stimulation group (0.88 ± 0.03 vs 1.17 ± 0.05 and 0.82 ± 0.23 vs 1.81 ± 0.27, both P < 0.05) and decreased the concentrations of MMP-2 and MMP-9 in culture media versus IGF-I stimulation group ((21.70 ± 0.32) vs (29.15 ± 0.34) ng/ml and (0.22 ± 0.01) vs (0.29 ± 0.01) ng/ml, both P < 0.01)., Conclusions: IGF-I induces the expressions of MMP-2 and MMP-9 in alveolar epithelial cell through ERK signaling pathway. And it is associated with the disruption of epithelial basement membrane and the development of lung fibrosis.