IL-17 mRNA in sputum of asthmatic patients: linking T cell driven inflammation and granulocytic influx?
BACKGROUND
The role of Th2 cells (producing interleukin (IL-)4, IL-5 and IL-13) in allergic asthma is well-defined. A distinct proinflammatory T cell lineage has recently been identified, called Th17 cells, producing IL-17A, a cytokine that induces CXCL8 (IL-8) and recruits neutrophils. Neutrophilic infiltration in the airways is prominent in severe asthma exacerbations and may contribute to airway gland hypersecretion, bronchial hyper-reactivity and airway wall remodelling in asthma.


OBJECTIVE
to study the production of IL-17 in asthmatic airways at the mRNA level, and to correlate this with IL-8 mRNA, neutrophilic inflammation and asthma severity.


METHODS
We obtained airway cells by sputum induction from healthy individuals (n = 15) and from asthmatic patients (n = 39). Neutrophils were counted on cytospins and IL-17A and IL-8 mRNA expression was quantified by real-time RT-PCR (n = 11 controls and 33 asthmatics).


RESULTS
Sputum IL-17A and IL-8 mRNA levels are significantly elevated in asthma patients compared to healthy controls. IL-17 mRNA levels are significantly correlated with CD3gamma mRNA levels in asthmatic patients and mRNA levels of IL-17A and IL-8 correlated with each other and with sputum neutrophil counts. High sputum IL-8 and IL-17A mRNA levels were also found in moderate-to-severe (persistent) asthmatics on inhaled steroid treatment.


CONCLUSIONS
The data suggest that Th17 cell infiltration in asthmatic airways links T cell activity with neutrophilic inflammation in asthma.
Bullens
Dominique M A
DM
Department of Experimental Medicine, Clinical Immunology, Katholieke Universiteit Leuven, (KULeuven), Leuven, Belgium. Dominique.Bullens@med.kuleuven.be
Truyen
Els
E
Coteur
Liesbeth
L
Dilissen
Ellen
E
Hellings
Peter W
PW
Dupont
Lieven J
LJ
Ceuppens
Jan L
JL
D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000235:genetics / Q000276:immunology* / Q000473:pathology*; D005260:Female; D006098:Granulocytes / Q000276:immunology*; D006801:Humans; D020381:Interleukin-17 / Q000235:genetics / Q000276:immunology*; D016209:Interleukin-8 / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D013183:Sputum / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
D020381:Interleukin-17; D016209:Interleukin-8; D012333:RNA, Messenger