Increased HLA-DR Expression on M2a Monocytes and Helper T Cells in Patients with COPD and Asthma-COPD Overlap Contributes to Disease Severity via Apoptosis and ROS.

OBJECTIVE

Ongoing debates focus on the role of human leukocyte antigen (HLA) class II expression in shaping clinical phenotypes of chronic inflammatory airway diseases. This study seeks to clarify the impact of class II HLA on chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap (ACO).

METHOD: The expression levels of HLA-DQ/DR in blood immune cells were analyzed in 116 participants: 41 with COPD, 37 with ACO, 20 with pure asthma, and 18 healthy subjects (HS).

RESULTS

In the COPD group, HLA-DR protein expression levels were significantly elevated on blood M2a monocytes (7695 ± 3743 vs. 5391 ± 3153 MFI, p = 0.026), helper T cells (2551 ± 956 vs. 1836 ± 531 MFI, adjusted p = 0.018), cytotoxic T cells (1591 ± 531 vs. 1360 ± 477 MFI, adjusted p = 0.036), and B cells (20,667 ± 7985 vs. 15,694 ± 2003 MFI, adjusted p = 0.031) compared to the HS group. Conversely, no significant changes were observed in the asthma group. In ACO patients, helper T cells showed increased HLA-DR protein expression (2416 ± 914 MFI; adjusted p = 0.016) compared with the HS group. Higher levels of HLA-DR expression correlated with reduced pulmonary function, frequent exacerbations, and more severe symptoms. Following one year of treatment in 14 COPD and 16 ACO patients, HLA-DR protein expression on blood helper T cells, cytotoxic T cells, M2a monocytes, and neutrophils significantly declined (all p < 0.05). In vitro experiments demonstrated that exposure of M2- or M1-polarized THP-1 cells to a stimulus mix containing cigarette smoke extract, house dust mite antigens, and lipopolysaccharide led to up-regulation of HLA-DR expression. This response was linked to increased apoptosis and reduced production of reactive oxygen species.

CONCLUSIONS

Up-regulation of HLA-DR in COPD and ACO patients may represent a novel biomarker for assessing disease severity and treatment response. Additionally, it could serve as a useful tool to distinguish COPD and ACO from asthma.