Associations Between Sputum Torque Teno Virus Load and Lung Function and Disease Severity in Patients With Chronic Obstructive Pulmonary Disease

Abstract

Purpose: Viral load of Torque Teno virus (TTV) is elevated in immunosuppressed patients. The weakened immune response is typical in chronic obstructive pulmonary disease (COPD) patients. However, the relationship between TTV and COPD is still unknown. Patients and Methods: We enrolled 91 patients admitted to hospitals with acute exacerbation of COPD (AECOPD) between January 2017 and August 2017 (ClinicalTrials.gov ID, NCT03236480). Sputum samples were gathered during hospitalization and the 120-day follow-up. TTV distribution and genogroups were assessed, and the associations between viral loads and clinical parameters were analyzed. Results: TTV DNA was detected in 95.6% of COPD patients, and the viral load was nearly invariable at the stable and exacerbation states. Most TTV DNA-positive patients carried four distinct genotypes. Sputum load of TTV was positively associated with RV/TLC (r = 0.378, p = 0.030), and negatively correlated with FEV1/pre and FEV1/FVC (r = -0.484, -0.432, p = 0.011, 0.024, respectively). Neutral correlation between the TTV DNA load and COPD assessment test (CAT) scores (r = 0.258, p = 0.018) was observed. Conclusion: Sputum loads of TTV DNA could be a novel indicator for lung function and disease severity assessment in COPD patients.

Keywords: biomarker; chronic obstructive pulmonary disease; disease severity; lung function; torque teno virus.

Conflict of interest statement

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 © 2021 Xie, Xue, Jiao, Wu, Yu, Zhao, Xu, Deng, Fang, Zheng and Gao.

Figures

Figure 1

(A) Torque Teno virus (TTV) DNA log10 sputum loads at admission for 74 patients and at discharge for 85 patients. The Mann-Whitney U test was performed to compare the median values, and no remarkable differences were found between the two points (p = 0.870). (B) TTV DNA log10 sputum loads at admission, at discharge and during follow-up (22, 21, and 20 patients at 1, 2, and 3 months after discharge, respectively) in cohort B. Kruskal-Wallis test was performed to compare the median values, and no significant differences were found between the points in time (p = 0.270). Thick horizontal bars represent the median value of each point.

Figure 2

(A) Correlation between the Torque Teno virus (TTV) DNA load and the residual volume (RV)/total lung capacity (TLC) in 33 patients. (B,C) Correlation between the TTV DNA load and forced expiratory volume in 1 s (FEV1)/pre, FEV1/forced vital capacity (FVC) in 27 patients. The correlations between the values were assessed by the Spearman's rank test. The r and p-values are shown.

Figure 3

(A) Correlation between the Torque Teno virus (TTV) DNA load at discharge and the CAT scores in 84 patients. (B) TTV DNA load at discharge for 46 patients with 6 MWD < 250 m and 38 patients with 6 MWD ≥ 250 m. The correlation between the values was assessed by the Spearman's rank test. The Mann-Whitney U test was performed to compare the median values. The r and p-values are shown. Thick horizontal bars represent the median value of each point.

Figure 4

(A) Correlation between the Torque Teno virus (TTV) DNA load at discharge and the number of eosinophils in 85 patients. (B) TTV DNA load at admission for 14 patients with a number of eosinophils < 0.02 × 109/L and 60 patients with a number of eosinophils ≥ 0.02 × 109/L. The correlation between the values was assessed by the Spearman's rank test. The Mann-Whitney U test was performed to compare the median values. The r and p-values are shown. Thick horizontal bars represent the median value of each point.