Toll-like receptors 4 and 2 expression in the bronchial mucosa of patients with cystic fibrosis.
BACKGROUND
Cystic fibrosis (CF) is a lung disease characterized by chronic infection with Gram-negative bacteria Pseudomonas aeruginosa and Gram-positive bacteria Staphylococcus aureus. Recently, toll-like receptor (TLR) 4 has been shown to be responsible for the lipopolysaccharide (LPS)-mediated immune response. While TLR2 mediates responses driven by bacterial lipoproteins and peptidoglycans from Gram-positive bacteria, LPS derived from P aeruginosa may stimulate the immune response in the airways of patients with CF via activation of TLR4.


OBJECTIVE
To investigate TLR4 and TLR2 expression in the bronchial mucosa of patients with CF and normal control subjects.


METHODS
Endoscopic bronchial biopsies from seven patients with CF and six healthy control subjects were obtained. TLR4 and TLR2 expression was assessed using immmunocytochemistry. Real-time polymerase chain reaction was used to detect TLR4 messenger RNA in blood cells from patients with CF and to compare TLR4 expression in CF bronchial epithelial cells with non-CF bronchial epithelial cells.


RESULTS
In patients with CF, the number of TLR4-positive cells was significantly increased in their submucosa (P<0.05) but significantly reduced in their epithelium compared with control subjects (P<0.05). The majority of TLR4-positive cells were neutrophils. Patients with CF (n=4) and control subjects (n=4) had a similar percentage of TLR4-expressing neutrophils and monocytes/lymphocytes in peripheral blood. CF cells (IB-3) had significantly decreased basal TLR4 messenger RNA expression compared with non-CF cells (Calu-3) (P<0.05). Although there was a trend toward reduced TLR2 expression in the airway epithelium of patients with CF (P=0.07), there was no significant difference in TLR2 expression in the submucosa of patients with CF compared with that of control subjects.


CONCLUSIONS
Both TLR4 and TLR2 expression in the bronchial epithelium of patients with CF were significantly reduced compared with healthy control subjects. In contrast, the number of TLR4-positive neutrophils in the submucosa of patients with CF was higher than in control subjects. This may suggest that the loss of epithelial TLR expression may contribute to the impaired defense against LPS.
Hauber
Hans-Peter
HP
Meakins-Christie Laboratories, McGill University, Montreal, Canada.
Tulic
Meri K
MK
Tsicopoulos
Anne
A
Wallaert
Benoit
B
Olivenstein
Ron
R
Daigneault
Patrick
P
Hamid
Qutayba
Q
D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000032:analysis; D001707:Biopsy, Needle; D001980:Bronchi / Q000166:cytology / Q000473:pathology*; D016022:Case-Control Studies; D002478:Cells, Cultured; D003550:Cystic Fibrosis / Q000235:genetics / Q000473:pathology*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D009092:Mucous Membrane / Q000473:pathology; D011336:Probability; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
D015415:Biomarkers; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors