Differences in Innate Lymphoid Cell profiles between COPD, asthma, smoking controls and non-smoking healthy controls

Abstract

<b>Introduction:</b> Innate lymphoid cells (ILCs) are divided into different subsets, each with specific functions in controlling tissue homeostasis and host defence. However, ILCs also play a role in chronic inflammation and have been implicated in the pathogenesis of asthma and Chronic Obstructive Pulmonary Disease (COPD). <b>Aims and objectives:</b> To compare ILC subsets in clinically stable COPD, asthma patients, and smoking and non-smoking healthy controls. <b>Methods:</b> Peripheral blood ILCs were characterized by flow cytometry. Principal Component Analyses (PCA) was used to compare the obtained ILC profiles between the two patient groups and the controls. A subanalysis was performed in COPD and smoking controls. <b>Results:</b> In total 111 individuals were included: 39 COPD patients, 37 asthma patients, 19 smoking and 16 non-smoking healthy controls. The proportions of ILC1s of ILCs as well as the frequencies of CD4+ cells within the ILC1 populations were significantly elevated in COPD patients, compared with asthma patients and non-smoking healthy controls. A PCA additionally showed that the frequency of CD4-CD45RO+ cells within the ILC1 population could separate asthma patients and non-smoking controls. A subanalysis showed significantly elevated proportions of cKit+CD45RO+ cells within the ILC2 population and NKdim frequencies in COPD (n=29) compared to (current smokers and pack years matched) smoking controls (n=19). <b>Conclusion:</b> Analyses of our patient cohorts reveal significant differences in the ILC-profiles of COPD patients compared to asthma patients and (smoking) controls, indicating that ILC-subsets in peripheral blood can discriminate between COPD inflammation and smoking exposure.