Cytokine production of mononuclear leukocytes in response to respiratory syncytial virus is increased in COPD but suppressed in non-COPD tobacco smokers

Abstract

Background: Respiratory syncytial virus (RSV) induces exacerbations of chronic obstructive pulmonary disease (COPD) that are critical for disease progression and burden. COPD subjects have an increased susceptibility to viral respiratory infections. We aimed to identify underlying systemic immune pathologies that could be used as drug targets to reduce exacerbations.

Methods: Peripheral blood mononuclear cells were isolated from 16 healthy never smokers, 17 current smokers without airflow limitation, and 17 COPD subjects. The cells were cultured and infected with RSV for 24 h or seven days. IFNα, T-cell- and inflammatory cytokines, the expression of interferon-stimulating genes (ISGs), and virus load in supernatants were measured by ELISA or real-time PCR, respectively. Data were compared between the three patient groups.

Results: RSV induced CCL2, CCL5, IFNα, IFNγ, IL1-β, IL-6, IL-8, and TNFα but not IL-4, IL-5, IL-17, GM-CSF, and TGFβ. CCL2 was unchanged between the groups. All other cytokines were either increased or produced for a longer period of time in COPD but were reduced or not produced at all in smokers. Virus copy numbers were increased in COPD but reduced in smokers. RSV induced MxA, OAS, and Viperin expression with differences between the groups.

Conclusion: Circulating immune cells in COPD might cause cytokine overproduction in response to RSV after recruitment to the site of infection and might contribute to the increase in inflammation in exacerbations. This might be explained by differences in RSV replication efficacy and ISG expression. We provide first indication for ISGs and circulating cells as drug targets to reduce or prevent exacerbations.

Supplementary Information: The online version contains supplementary material available at 10.1186/s10020-025-01277-4.

Keywords: COPD; Circulating immune cells; Cytokine overproduction; Exacerbation; RSV.

Fig. 1

RSV replication in PBMCs. PBMCs from healthy never smokers (NS), current tobacco cigarette smokers without airflow limitation (S), and COPD subjects (5 × 10⁵cells per approach) were infected with RSV-A2 at the given multiplicities if infection (MOI). After 24 h and 7 days replication was measured by real time RT-RCR. Data are presented as median with scatter. N numbers are according to Table 1, two probes of S and two probes of COPD were excluded because of technical errors or insufficient sample material. Data were analyzed with Wilcoxon signed rank tests (vs. input) and successive Mann Whitney tests (order: NS vs. COPD, NS vs. S, S vs. COPD). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001 compared to input (dashed line) if placed on top of bars or between groups as indicated. Dashed line: RSV input

Fig. 2

ISG gene expression in response to RSV in PBMCs. PBMCs from never smokers (NS), current tobacco cigarette smokers without airflow limitation (S), and COPD subjects were infected with RSV-A2 at a multiplicity of infection (MOI) of 1. After 24 h and 7 days, the mRNA levels of Viperin (A, B), OAS (C, D), and MXA (E, F) were measured by Taqman real-time RT-PCR. Data are presented as median with scatter. N numbers are according to Table 1, one probe of COPD was excluded because of insufficient sample material. The data were compared by Wilcoxon T-test and by Kruskal-Wallis test with post hoc Dunn test. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001