Abstract
Background: Monocytes play an important role in immune and inflammatory diseases and monocyte subsets are predictors of disease in certain conditions. Expression of the chemokine receptors, CCR2 and CX3CR1 on monocyte subsets relates to their function and can be used in their characterization. Our objective was to determine whether CD14, CD16, CCR2 and CX3CR1 on monocyte subsets are potential indicators of asthma severity.
Methods: Blood samples were collected from Saudi Arabian patients with asthma and normal healthy individuals. Six-color flow-cytometry phenotypic analysis was used to identify human blood monocyte subsets, based on their expression of CD14 and CD16 following CD45 gating. Expression of CCR2 and CX3CR1 was analysed on classical (CD14++CD16-), intermediate (CD14++CD16+) and non-classical (CD14+CD16++) subsets and correlated with disease severity.
Results: We demonstrated a significant increase in percentage of total CD45-positive monocytes in the blood of patients with severe asthma, but the proportion of the individual monocyte subsets was not significantly changed when patients with mild, moderate and severe asthma were compared with healthy individuals. CD16 expression (Mean Fluorescence Intensity, MFI) was decreased on intermediate and non-classical subsets in patients with severe asthma compared to healthy controls. CX3CR1 expression was also lower, with a lower percentage of cells expressing CX3CR1 in the non-classical CD14+CD16++ subset in all patients with asthma and this was inversely related to the percentage of cells expressing CCR2.
Conclusions: CCR2 expression on monocytes indicated a tendency toward more phagocytic monocytes in patients with asthma. The differential expression of CD16, CX3CR1 and CCR2 on monocyte subsets in peripheral blood indicates modulation of the inflammatory response and suggests a role for monocytes in asthma pathogenesis.
Methods: Blood samples were collected from Saudi Arabian patients with asthma and normal healthy individuals. Six-color flow-cytometry phenotypic analysis was used to identify human blood monocyte subsets, based on their expression of CD14 and CD16 following CD45 gating. Expression of CCR2 and CX3CR1 was analysed on classical (CD14++CD16-), intermediate (CD14++CD16+) and non-classical (CD14+CD16++) subsets and correlated with disease severity.
Results: We demonstrated a significant increase in percentage of total CD45-positive monocytes in the blood of patients with severe asthma, but the proportion of the individual monocyte subsets was not significantly changed when patients with mild, moderate and severe asthma were compared with healthy individuals. CD16 expression (Mean Fluorescence Intensity, MFI) was decreased on intermediate and non-classical subsets in patients with severe asthma compared to healthy controls. CX3CR1 expression was also lower, with a lower percentage of cells expressing CX3CR1 in the non-classical CD14+CD16++ subset in all patients with asthma and this was inversely related to the percentage of cells expressing CCR2.
Conclusions: CCR2 expression on monocytes indicated a tendency toward more phagocytic monocytes in patients with asthma. The differential expression of CD16, CX3CR1 and CCR2 on monocyte subsets in peripheral blood indicates modulation of the inflammatory response and suggests a role for monocytes in asthma pathogenesis.
Original language | English |
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Article number | 64 |
Number of pages | 11 |
Journal | Allergy, Asthma, and Clinical Immunology |
Volume | 15 |
DOIs | |
Publication status | Published - 4 Nov 2019 |
Bibliographical note
FundingReem Al-Rashoudi was funded as part of the Saudi Arabian Cultural Bureau, External Joint Supervision Program (EJSP) to do a PhD degree jointly between Aberdeen University, UK and King Saud University, SA. The funding body played no part in the preparation of the data or the manuscript.
Acknowledgments
This work was supported by a grant from ‘Research Center, Center for Female Scientific and Medical Colleges, Deanship of Scientific Research, King Saud University. Support from the Saudi Arabian Cultural Bureau and External Joint Supervision Program (EJSP) is also gratefully acknowledged. Professor Graeme Devereux (Liverpool School of Tropical Medicine) provided helpful discussion on asthma. Dr. Raif Yuecel and Amer Al-Mazrou provided expertise for flow cytometry and analysis.
Keywords
- Saudi Arabia
- chemokine receptor
- flow cytometry
- CD14
- biomarker
- Biomarker
- Chemokine receptor
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Heather Wilson
- School of Medicine, Medical Sciences & Nutrition, Microbiology and Immunity
- School of Medicine, Medical Sciences & Nutrition, Medical Sciences - Chair in Immunology
- School of Medicine, Medical Sciences & Nutrition, Aberdeen Cardiovascular and Diabetes Centre
- School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences
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Iain Fraser Cytometry Centre
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