Alcohol functionally upregulates Toll-like receptor 2 in airway epithelial cells.
BACKGROUND
Alcoholics are known to have more severe airway diseases of the lung, such as bronchitis. Little is known about why this phenomenon is observed. We hypothesized that alcohol may modulate Toll-like receptor 2 (TLR2), which regulates inflammation caused by gram-positive bacteria.


METHODS
Airway epithelial cells [primary bronchial epithelial cells (NHBE) and 16HBE 14o-] were exposed to 0 to 100 mM alcohol for 0 to 24 hours. Real time PCR was used to quantify TLR2 mRNA. Protein levels of TLR2 were determined using Western blots and fluorescence activated cell sorting (FACS) on cells exposed to 0, 50, and 100 mM alcohol. Finally, cells were "primed" with alcohol, stimulated with a TLR2 agonist (peptidoglycan), and interleukin 8 (IL-8) release was measured.


RESULTS
Alcohol, at biologically relevant concentrations (25 to 100 mM), caused a 2 to 3-fold time- and concentration-dependent increase in TLR2 mRNA in normal human bronchial epithelial cells and 16HBE 14o- cells. Western blots for TLR2 revealed a qualitative increase in TLR2 protein in cells exposed to 100 mM alcohol. FACS showed that TLR2 was quantitatively increased on the surface of airway epithelial cells that were exposed to alcohol. Airway cells that were primed with alcohol produced nearly twice as much IL-8 in response to 40 ng of peptidoglycan than naive cells.


CONCLUSIONS
Alcohol upregulates TLR2 message and protein in the airway epithelium. This leads to exaggerated inflammation in response to environmental stimuli that would normally be well tolerated in airway epithelial cells. This may be a partial explanation of why alcoholics have more severe airway disease than nonalcoholics.
Bailey
Kristina L
KL
Department of Internal Medicine, Pulmonary, Critical Care, Sleep & Allergy Section, University of Nebraska Medical Center, Omaha, Nebraska 68198-5815, USA.
Wyatt
Todd A
TA
Romberger
Debra J
DJ
Sisson
Joseph H
JH
D000437:Alcoholism / Q000150:complications; D001980:Bronchi / Q000187:drug effects* / Q000378:metabolism; D001991:Bronchitis / Q000139:chemically induced* / Q000378:metabolism; D002478:Cells, Cultured; D002492:Central Nervous System Depressants / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D000431:Ethanol / Q000009:adverse effects*; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D010457:Peptidoglycan / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D051195:Toll-Like Receptor 2 / Q000378:metabolism*; D015854:Up-Regulation
D002492:Central Nervous System Depressants; D016209:Interleukin-8; D010457:Peptidoglycan; D012333:RNA, Messenger; D051195:Toll-Like Receptor 2; D000431:Ethanol