Obese asthmatics are characterized by altered adipose tissue macrophage activation

Summary Background Adipose tissue‐derived inflammation is linked to obesity‐related comorbidities. This study aimed to quantify and immuno‐phenotype adipose tissue macrophages ( ATM s) from obese asthmatics and obese non‐asthmatics and to examine associations between adipose tissue, systemic and airway inflammation. Methods Visceral ( VAT ) adipose tissue and subcutaneous ( SAT ) adipose tissue were collected from obese adults undergoing bariatric surgery and processed to obtain the stromovascular fraction. Pro‐inflammatory (M1) and anti‐inflammatory (M2) macrophages were quantified by flow cytometry. Cytospins of induced sputum were stained for differential cell counts. Plasma C‐reactive protein ( CRP ) and CD 163 were measured by ELISA . Results VAT contained a higher number of ATM s compared to SAT . A higher percentage of M1 ATM s was observed in VAT of obese asthmatics compared to obese non‐asthmatics. The M1:M2 ratio in VAT was negatively associated with FEV 1 %. Sputum macrophage count was correlated positively with M1 ATM s and negatively with M2 ATM s in VAT . In obese asthmatics, CRP was positively associated with M1:M2 ratio in VAT . There were no associations with CD 163. An elevated ratio of M1:M2 ATM s was observed in VAT of obese asthmatics with increased disease severity. Conclusions and Clinical Relevance Visceral inflammation with increased pro‐inflammatory macrophages (M1) occurs in obese asthma and may be a determinant of systemic inflammation and asthma severity.