Alternation Of Circulating Monocyte Subsets In Patients With Acute Exacerbations Of Chronic Obstructive Pulmonary Disease And Its Relationship With Disease Diagnosis And Prognosis

Objective The aim of this study is to investigate the alternation of peripheral blood monocyte subsets in AECOPD patients in comparison with healthy donors and long-time smokers in surface marker expression and cytokine production.We also evaluated the potential of blood monocyte subsets ratio(NI ratio)as a biomarker for AECOPD diagnosis and prognosis.Methods Nineteen healthy non-smokers,19 current smokers without respiratory symptoms,and 23 AECOPD patients were recruited in this study.Peripheral blood of each group,at the time of hospital admission and remission,respectively,were collected.Serum cytokine levels were measured by Cytometric Bead Array(CBA)kit.Cytokine secretion of CD14+ monocytes in respond to LPS,and surface marker expression of monocyte subsets were analyzed by flow cytometry.Clinical parameters,pulmonary function,and routine laboratory tests were performed for each patient.Results 1.Monocytes of AECOPD patients showed increase of classcial and intermediate monocyte subsets and reduction of non-classical subset,with impaired TNF-? and IL-1? production in response to LPS and diminished expression of HLA-DR on cell surface.2.We showed that monocytes in AECOPD patients could be divided into two subpopulation according to FSC and SSC value: typical monocytes(T Mo)that similar with monocytes in healthy individual maintain relatively stable number in circulation;atypical monocytes only occurred in the circulation of AECOPD patients.Like typical monocytes,the atypical monocytes of AECOPD patients could be divided into classical,intermediate and non-classcial monocytes.Like total monocytes,both typical and atypical monocytes showed increased percentage of intermediate subset but decreased non-classical subset in AECOPD patients compared to healthy control.Thus classical and intermediate monocytes became the dominated subsets in typical,atypical and total monocytes(>95%).3.As for surface markers related to the monocytes migration,overexpression of CCR2 and ICAM-1 in classical subset and down-regulation of ICAM-1 level in non-classical subset were observed in total monocytes of AECOPD patients.However,further analysis revealed that the expression of CCR2 increased significantly only on classical subset in atypical monocytes,but not in typical monocytes,and the expression of ICAM-1 increased significantly in all three subsets in atypical monocytes,but decreased dramatically in typical monocytes.4.We showed diminished m HLA-DR level in CD14+ total monocytes of AECOPD patients,and the differences in HLA-DR levels between patients and control groups were mostly attributed to down-regulated HLA-DR expression in classical subset.However,we further showed that the expression of HLA-DR decreased dramatically only in typical monocytes in AECOPD patients but not in atypical monocytes.5.In comparison with control groups,the expression of CX3CR1 decreased in all the three subsets in typical,atypical and total monocytes,which was remarkably increased at remission.6.We found a decrease of NI ratio(Non-classical/Intermediate ratio)in AECOPD patients and a significant increase of NI ratio at remission.Further analysis showed high sensitivity and specificity of NI ratio in assessing AECOPD at admission in correlating with ROC curve.More importantly,we found that the NI ratio showed a negative correlation with the length of hospital stay.Conclusions Our data demonstrated altered monocyte subsets with changes in the expression of surface chemokine receptors/adhesion molecules and production of cytokines in AECOPD patients.These alternations were improved at disease remission.Moreover,we propose a new monocyte subset dividing strategy by FSC and SSC in FACS.Importantly,we found that NI ratio in AECOPD patients was correlated with disease outcomes,thus likely being a valuable biomarker for COPD diagnosis and prognosis. All these findings suggest that monocytes participate the pathogenesis of AECOPD and the alternation in monocyte subsets may be used as a biomarker in COPD diagnosis and prognosis.Our study open up a novel avenue for disclosing the underlying immunopathological mechanisms of AECOPD and COPD.