Inflammatory activity is still present in the advanced stages of idiopathic pulmonary fibrosis

Serum lactate dehydrogenase is associated with impaired lung function: NHANES 2011-2012

BACKGROUND

Serum lactate dehydrogenase levels reflect disease status in a variety of organs, but its role in indicating pulmonary function is not yet clear. Therefore, this study explored the correlation between pulmonary function and serum lactate dehydrogenase, and investigated thresholds for changes in pulmonary function indicators in the total population as well as in different strata of the population.

METHODS

Based on data from the National Health and Nutrition Examination Survey (NHANES) 2011-2012 (n = 3453), univariate and stratified analyses were performed to investigate factors associated with pulmonary function, and multiple regression analysis was used to further investigate the specific relationship with serum lactate dehydrogenase. Smoothed curve fitting, threshold effect and saturation effect analysis were used to explore the threshold level of serum lactate dehydrogenase at the onset of changes in pulmonary function indicators.

RESULTS

Adjusted smoothed curve fit plots showed a linear relationship between serum lactate dehydrogenase levels and forced vital capacity and forced expiratory volume in one second: for each 1 U/L increase in serum lactate dehydrogenase levels, forced vital capacity decreased by 1.24 mL (95% CI = -2.05, -0.42, P = 0.0030) and forced expiratory volume in one second by 1.11 mL (95% CI = -1.82, -0.39, P = 0.0025).

CONCLUSIONS

Serum lactate dehydrogenase was negatively and linearly correlated with pulmonary function indices in the total population analyzed. Based on the total population and different population stratifications, this study determined the threshold values of serum lactate dehydrogenase at the onset of decline of pulmonary function in different populations. This provides a new serological monitoring indicator for patients suffering from respiratory diseases and has implications for patients with possible clinical impairment of pulmonary function. However, our cross-sectional study was not able to determine a causal relationship between these two factors, and further research is needed.

Genetic association of circulating C-reactive protein levels with idiopathic pulmonary fibrosis: a two-sample Mendelian randomization study

BACKGROUND

Several observational studies have found that idiopathic pulmonary fibrosis (IPF) is often accompanied by elevated circulating C-reactive protein (CRP) levels. However, the causal relationship between them remains to be determined. Therefore, our study aimed to explore the causal effect of circulating CRP levels on IPF risk by the two-sample Mendelian randomization (MR) analysis.

METHODS

We analyzed the data from two genome-wide association studies (GWAS) of European ancestry, including circulating CRP levels (204,402 individuals) and IPF (1028 cases and 196,986 controls). We primarily used inverse variance weighted (IVW) to assess the causal effect of circulating CRP levels on IPF risk. MR-Egger regression and MR-PRESSO global test were used to determine pleiotropy. Heterogeneity was examined with Cochran's Q test. The leave-one-out analysis tested the robustness of the results.

RESULTS

We obtained 54 SNPs as instrumental variables (IVs) for circulating CRP levels, and these IVs had no significant horizontal pleiotropy, heterogeneity, or bias. MR analysis revealed a causal effect between elevated circulating CRP levels and increased risk of IPF (OR_IVW = 1.446, 95% CI 1.128-1.854, P = 0.004).

CONCLUSIONS

The present study indicated that elevated circulating CRP levels could increase the risk of developing IPF in people of European ancestry.

Development and Validation of the Prognostic Index Based on Inflammation-Related Gene Analysis in Idiopathic Pulmonary Fibrosis

Background: Historically, idiopathic pulmonary fibrosis (IPF) was considered a chronic inflammation disorder, but this conception was reassessed in the past decades. Our understanding of the role of inflammation in IPF and its association with clinical significance remained incomplete.

Methods: We downloaded mRNA expression data of peripheral blood mononuclear cells (PBMCs) from the Gene Expression Omnibus (GEO) repository. Inflammation-related genes (IRGs) expressed differently between IPF and control (CTRL) were determined. In this study, we systemically analyzed the expression of differently expressed IRGs by comprehensive bioinformatic analysis, and then investigated their potential prognostic values. The related prognostic gene expressions were verified in our cohort.

Results: 110 differently expressed IRGs were identified in this study, including 64 upregulated and 46 downregulated IRGs. Three IRGs (S100A12, CCR7, and TNFSF4) were identified as potential hub genes for prognosis. Those genes were subsequently subjected to the construction of the prognostic models. In the results, IPF patients categorized as high risk demonstrated a poor overall survival rate compared to patients categorized as low risk. Based on this prognostic model, the area under the curve (AUC) of the survival-dependent receiver operator characteristic (ROC) for 1-year, 2-year, and 3-year survival rates was 0.611, 0.695, and 0.681, respectively, in the GSE28042 cohort. These observations were validated in the GSE27957 cohort, confirming the good prognostic effect of this model. The expression of the three genes was validated in our cohort. We also conducted a nomogram based on the three IRGs’ mRNA for quantitative IPF prognosis.

Conclusion: Three IRGs (S100A12, CCR7, and TNFSF4) were identified as potential markers for the prognosis of IPF.

Inflammatory mediators in various molecular pathways involved in the development of pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD) that is marked by scarring of lung tissue, ultimately leading to respiratory failure. The survival rate of IPF is disappointing and to date demonstrates a clinical quandary. The exact etiology of the disease remains under discussion. According to the recent hypothesis, inflammatory mediators cause severe damage to the alveolar epithelium leading to the impairment of the alveolar structure. The role of inflammation in the development of the IPF has been controversial for years. There are two schools of thought regarding the role of inflammation. One group of researchers claims that cell death and fibroblast dysfunction are the primary causes and inflammation is just a secondary cause of IPF. The other group claims inflammation to be the primary cause. Studies using human subjects have also reported inflammation as a critical element in IPF. Inflammatory cytokinesserve amajor rolein commencing theinflammatoryresponse in the lungs. Several cytokines are reported to be involved in different molecular mechanisms underlying IPF, someof which alsocontribute additionally by acting as growth factors. The present review addressed to explore the contribution of various inflammatory cytokines, growth factors, and various other inflammatory molecules activating the major molecular pathways involved during the development of IPF.

Effects of chronic immobilization stress on biokinetics and dosimetry of 67Ga in a murine model

The aim of this work is to determine the effect of chronic immobilization stress on kinetics and dosimetry of ⁶⁷Ga in a mouse model. A control group (CG) and a stress group (SG), each with 15 mice, were included in the study, and the latter group was subjected to a chronic immobilization stress model 2 h daily for 14 consecutive days. At day 13, ⁶⁷Ga-citrate was administered intraperitoneally (11.24 ± 0.44 MBq) to each mouse. Then, sets of three mice were obtained sequentially at 24, 36, 48, 60 and 72 h, in which the radionuclide activity was measured with an activity counter. The ⁶⁷Ga biokinetic data showed a fast blood clearance in the SG, with a mean residence time of 0.06 h. The calculated mean radiation absorbed doses were: liver (2.45 × 10^-03 Gy), heart (3.17 × 10^-04 Gy) and kidney (1.88 × 10^-04 Gy) in the SG. The results show that stress reduced weight gain by approximately 13% and also increased adrenal gland weight by 26%. On the other hand, chronic stress accelerates ⁶⁷Ga clearance after 24 h compared to normal conditions. It is concluded that murine organisms under chronic immobilization stress have higher gallium-67 clearance rates, decreasing the cumulated activity and absorbed dose in all organs.

Current advances in idiopathic pulmonary fibrosis: the pathogenesis, therapeutic strategies and candidate molecules

Idiopathic pulmonary fibrosis (IPF) is a type of chronic, progressive lung disease with unknown cause, which is characterized by increasing dyspnea and destruction of lung function with a high mortality rate. Evolving evidence demonstrated that the pathogenesis of IPF involved multiple signaling pathways such as inflammation, oxidative stress and fibrosis. However, drug discovery to prevent or revert IPF has been insufficient to cope with the development. Drug discovery targeting multiple links should be considered. In this review, we will brief the pathogenesis of IPF and discuss several small chemical entities toward the pathogenesis for IPF studied in animal models and clinical trials. The field of novel anti-IPF agents and the future directions for the prevention and treatment of IPF are detailed thoroughly discussed.

[18F]FDG PET/CT predicts progression-free survival in patients with idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by an unpredictable course. Prognostic markers and disease activity markers are needed. The purpose of this single-center retrospective study was to evaluate the prognostic value of lung fluorodeoxyglucose ([¹⁸F]-FDG) uptake assessed by standardized uptake value (SUV), metabolic lung volume (MLV) and total lesion glycolysis (TLG) in patients with IPF.

METHODS

We included 27 IPF patients (IPF group) and 15 patients with a gastrointestinal neuroendocrine tumor without thoracic involvement (control group). We quantified lung SUV mean and SUV max, MLV and TLG and assessed clinical data, high-resolution CT (HRCT) fibrosis and ground-glass score; lung function; gender, age, physiology (GAP) stage at inclusion and during follow-up; and survival.

RESULTS

Lung SUV mean and SUV max were higher in IPF patients than controls (p <0.00001). For patients with IPF, SUV mean, SUV max, MLV and TLG were correlated with severity of lung involvement as measured by a decline in forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO) and increased GAP score. In a univariate and in a multivariate Cox proportional-hazards model, risk of death was increased although not significantly with high SUV mean. On univariate analysis, risk of death was significantly associated with high TLG and MLV, which disappeared after adjustment functional variables or GAP index. Increased MLV and TLG were independent predictors of death or disease progression during the 12 months after PET scan completion (for every 100-point increase in TLG, hazard ratio [HR]: 1.11 (95% CI 1.06; 1.36), p = 0.003; for every 100-point increase in MLV, HR: 1.20 (1.04; 1.19), p = 0.002). On multivariable analysis including TLG or MLV with age, FVC, and DLCO or GAP index, TLG and MLV remained associated with progression-free survival (HR: 1.1 [1.03; 1.22], p = 0.01; and 1.13 [1.0; 1.2], p = 0.005).

CONCLUSION

FDG lung uptake may be a marker of IPF severity and predict progression-free survival for patients with IPF.

Annual Change in Pulmonary Function and Clinical Characteristics of Combined Pulmonary Fibrosis and Emphysema and Idiopathic Pulmonary Fibrosis: Over a 3-Year Follow-up

BACKGROUND

Combined pulmonary fibrosis and emphysema (CPFE) have different pulmonary function tests (PFTs) and outcomes than idiopathic pulmonary fibrosis (IPF). The intention of this study was to identify unknown differences between CPFE and IPF by a retrospective comparison of clinical data including baseline and annual changes in pulmonary function, comorbidities, laboratory findings, clinical characteristics and cause of hospitalization.

METHODS

This study retrospectively enrolled patients with CPFE and IPF who had undergone PFTs once or several times per year during a follow-up period of three years. Baseline clinical characteristics and the annual changes in the pulmonary function during the follow-up period were compared between 26 with CPFE and 42 patients with IPF.

RESULTS

The baseline ratio of forced expiratory volume in one second to forced vital capacity (FEV1/FVC%) in patients with CPFE was lower than that in patients with IPF (78.6±1.7 vs. 82.9±1.1, p=0.041). The annual decrease in FEV1/FVC in the CPFE was significantly higher than in the IPF. The annual decreases in diffusion capacity of carbon monoxide and FVC showed no significant differences between the two groups. The symptom durations of cough and sputum were in the CPFE significantly lower than in the IPF. The serum erythrocyte sedimentation rate level at the acute stage was significantly higher than in the IPF. There were no significant differences in the hospitalization rate and pneumonia was the most common cause of hospitalization in both study groups.

CONCLUSION

The annual decrease of FEV1/FVC was in patients with CPFE significantly higher than in the patients with IPF.

IL-4 polymorphisms, HRCT score and lung tissue markers in idiopathic pulmonary fibrosis

AIMS

We studied the influence of IL-4 gene polymorphisms on the IPF phenotype, i.e., extent of radiological changes (HRCT interstitial (IS) and alveolar (AS) score) and histopathological markers from lung biopsies.

PATIENTS AND METHODS

46 IPF patients underwent genotyping, 43 of them had HRCT and 14 patients had a surgical lung biopsy. The HRCT scans were evaluated for AS and IS. The histopathological evaluation comprised myofibroblast foci (MF), intensity of inflammation and fibrosis (Ashcroft score) and numbers of eosinophils and granulomas. For immunohistochemical evaluation primary antibodies against PAR-2, CD124, TGF beta, YY-1 and TSLP were used. The IL-4 and IL-4 R alpha gene polymorphisms were characterized.

RESULTS

We found a correlation between eosinophils in lung biopsies and AS. The Ashcroft score was higher in IL-4 HA 2 GCC and MF were more frequent in IL-4 HA 2 TCC carriers. A relationship was found between IL-4 (-1098) A2 T and PAR-2 expression and IL-4 (-590) A1 T, IL-4 HA1TTT and CD124 expression. AS was lower in IL-4 (-590) A1 C, in IL-4 HA1 TCC and in IL-4RA (+1902) A1 A carriers.

CONCLUSIONS

We suggest that the polymorphisms of IL-4 genes might influence the phenotype of IPF reflected by histopathological changes in lung biopsies and HRCT score.

Repeated low-dose computed tomography in current and former smokers for quantification of emphysema

OBJECTIVE

To quantify different emphysema evolution in current and former smokers.

METHODS

We retrospectively analyzed low-dose computed tomography scans from a lung cancer screening study of 59 current and 75 former smokers. The quantitative emphysema analysis was performed using a home-built software (YACTA version 0.9), yielding the parameters lung volume, emphysema volume (EV), emphysema index (EI), mean lung density, and 15th percentile.

RESULTS

The baseline EV and EI were significantly different (median EVformer =422 mL vs EVcurrent =249 mL, P = 0.0003; and median EIformer =7.6 % vs EIcurrent =4.1 %, P = 0.0001, respectively). On the annual repeat scan, the median EI and EV for former smokers had decreased significantly (ΔEIformer = -0.257%, P = 0.004; and ΔEVcurrent = -0.203 mL, P = 0.020), whereas there was no emphysema change in current smokers.

CONCLUSIONS

We were able to demonstrate different emphysema evolution in current versus former smokers; emphysema parameters decreased in the former smokers and remained stable in current smokers.

Cytokine gene polymorphisms and high-resolution-computed tomography score in idiopathic pulmonary fibrosis

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a serious disease with unknown cause and the influence of cytokine gene polymorphisms is presumed in the etiology and pathogenesis of the disease. We used high-resolution computed tomography (HRCT) as a marker of disease stage and progression and compared the alveolar and interstitial score with IL-1, IL-4, IL-12, IL-1RA and IL-4RA cytokine gene polymorphisms.

SUBJECTS AND METHODS

The IPF patients were all Caucasians from the Czech Republic and consisted of 20 females and 10 males, with a mean age of 65 years, range 36-85. The HRCT results were evaluated by an experienced viewer using the interstitial and alveolar score scales, which were based on the IPF HRCT description system from Gay SE, Kazerooni EA, Tows GB, Lynch JP, Gross BH, Cascade PN, et al. [Idiopathic pulmonary fibrosis. Predicting response to therapy and survival. Am J Respir Crit Care Med 1998;157:1063-72]. We evaluated the polymorphisms of cytokine genes utilizing a PCR with sequence-specific primers method.

RESULTS

The HRCT alveolar score was more pronounced in IL-4 RA (+1902) AG heterozygotes. The HRCT interstitial score was less severe in the IL-12 (-1188) AA homozygotes. According to progression of the HRCT interstitial score, the CC homozygosity at IL-1 RA (mspa 111100), the AA homozygosity at IL-4 RA (+1902) and CC homozygosity at IL-4(+33) positions were more frequent in patients with stable disease compared to those with progressive disease.

CONCLUSIONS

We assume from our data that the polymorphisms of IL-4, IL-4RA, IL-1RA and IL-12 genes (genes of cytokines with regulatory activity) might influence the phenotype of IPF as shown by measurable changes in HRCT investigations.