Decreased T-bet expression and changes in chemokine levels in adults with asthma

Authors


Dr Fanny W. S. Ko, Department of Medicine and Therapeutics, Prince of Wales Hospital, 30–32, Ngan Shing Street, Shatin, NT, Hong Kong SAR.
E-mail: fannyko@cuhk.edu.hk

Summary

T-bet is a novel transcription factor regulating lineage commitment of T helper (Th) lymphocytes to a predominant Th1 phenotype. Previous studies on T-bet and asthma focused mainly on bronchial biopsy specimens. This study assessed the relationship between T-bet expression and levels of selected chemokines in the peripheral blood of asthmatics. Blood was collected from 24 steroid-naive asthmatics, 39 asthmatics on inhaled corticosteroid and 32 age- and sex-matched controls for assay of T-bet expression, specific IgE and chemokines (interferon-gamma inducible protein-10 (IP-10/CXCL10), monokines induced by interferon-gamma (MIG/CXCL9), monocyte chemotactic protein-1 (MCP-1/CCL2), regulated upon activation normal T cell expressed and secreted (RANTES/CCL5) and interleukin-8 (IL-8/CXCL8) levels. T-bet mRNA expression was assessed by real-time quantitative reverse transcription–polymerase chain reaction (RT–PCR). Chemokine levels were assessed by immunofluorescence flow cytometry. The mean (s.d.) age and forced expiratory volume in 1 s (FEV1)% predicted of the asthmatics were 43·6 (14·6) years and 85·9 (20·0)%, respectively. The median (IQR) T-bet expression after normalization with β-actin was suppressed in asthmatics versus controls [asthmatics 0·71 (0·59) versus controls 1·07 (1·14), P = 0·03].The median (IQR) of plasma RANTES was elevated, whereas IP-10 was suppressed in asthmatics versus controls (RANTES: 13 658·0 (13673·3) versus 6299·5 (19 407·8) pg/ml, P = 0·03; IP-10: 1047·6 (589·8) versus 1306·4 (759·9) pg/ml, P = 0·001). There was a weak and negative correlation between T-bet expression and RANTES level in the asthmatics (r = –0·29, P = 0·032). T-bet could be measured in peripheral blood and its expression was suppressed in asthmatics. This is in keeping with asthma being a predominantly Th2 disease and T-bet probably plays a role in the pathogenesis of asthma. Further studies are needed to explore the potential application of peripheral blood monitoring of T-bet.

Ancillary