engleski

Inflammatory effects of TLR2/4 receptor agonists in THP-1 monocytic cell line

Chronic obstructive pulmonary disease (COPD) is characterized by enhanced chronic airway and lung inflammation. Smoking is the major risk factor for COPD in genetically predisposed individuals. Toll like receptors (TLR) are involved in regulation of innate and acquired immunity, and they play an important role in defence against pathogen infections as well as in sterile inflammation. It is believed that cigarette smoke and other noxious environmental factors affect TLR receptors causing their activation, which contributes to the development of chronic inflammation. Our aim was to assess toxicity and inflammatory effects of lipopolysaccharide (LPS), a TLR4 agonist, and lipoteichoic acid (LTA), a TLR2 agonist, in monocytic cell line THP-1 used as a model of systemic compartment of COPD. THP-1 cells were differentiated into macrophage-like cells, and then treated with various concentrations of LPS (0.1, 1 and 5 μg/ml) and LTA (0.1, 1 and 5 μg/ml). Cytotoxicity was determined by MTS cell viability assay and lactate dehydrogenase (LDH) activity assay. Pro-inflammatory cytokines IL-1β, IL-6 and TNF-α were determined in cell supernatants by ELISA method. Expression and activation of mitogen-activated protein kinases (MAPKs) were determined by Western blot method. MTS assay showed statistically significant differences in cell viability for 0.1 and 1 μg/ml LPS after 24h. Cells treated with 0.1, 1 and 5 μg/ml LPS, and with 1 and 5 μg/ml LTA had statistically significant differences in LDH leakage from cells. Only IL-1β was detectable in supernatants of non-treated cells, whereas all applied concentrations of LPS significantly induced production of IL-1β, IL-6 and TNF-α. LTA induced production of IL-1β and TNF-α at 0.1, 1 and 5 μg/ml, but IL-6 was induced only by 5 μg/ml LTA. In addition, treating cells with 0.1 and 1 μg/ml LPS for 30 min induced activation of ERK and p38 MAPK. In conclusion, both LPS and LTA caused some changes in cell membrane integrity without significant alterations in cell viability (as determined by MTS assay). In addition, they induced strong pro-inflammatory response in THP-1 cells. Therefore, we suggest that LPS and LTA might be considered as good surrogate agents for mimicking inflammatory processes that occur in COPD.

chronic obstructive pulmonary disease ; inflammation ; TLR receptor ; MAP kinases ; THP-1 cells

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