engleski

Activity of apoptotic and inflammatory caspases in THP-1 cells treated with extracellular Hsp70

Introduction: Extracellular Hsp70 (eHsp70) was shown to be increased in serum of patients with lung diseases, such as chronic obstructive pulmonary disease (COPD). Some studies demonstrated that eHsp70 can act pro-inflammatory and trigger sterile inflammation via Toll like receptors (TLR) 2 and 4. Aims and objectives: We hypothesized that eHsp70 might induce inflammatory, but not necessarily cytotoxic effects in this cell line. Therefore, we assess activity of caspases-1, -3/7, -8 and -9 in PMA-differentiated THP-1 macrophage-like cells, which could be used as a model for systemic component of COPD. Methods: THP-1 cells were treated with 0.3, 1 and 3 g/mL low endotoxin human Hsp70 recombinant protein (rhHsp70) for 2, 4, 6 and 8 hours. Caspases’ activity was measured with Caspase-Glo luminescent assays. Results: In THP-1 cells, rhHsp70 did not influence caspase-8 or caspase-9 activation. However, rhHsp70 in all concentrations applied inhibited caspase-3 activity after 8 h (P=0.0103, P=0.0221 and P=0.0140 for 0.3, 1 and 3 g/mL rhHsp70, respectively, vs. non-treated cells). On the other hand, 1 g/mL rhHsp70 induced significant activation of caspase-1 after 2 and 4 h (P=0.0473 and P=0.0252, respectively, vs. non-treated cells), while 3 g/mL rhHsp70 induced significant activation of caspase-1 after 4 and 8 h (P=0.0092 and P=0.0089, respectively, vs. non-treated cells). Conclusions: Apoptotic caspases were inactive, while pro-inflammatory caspase-1 was strongly activated by rhHsp70 in THP-1 cells. The results obtained show that extracellular Hsp70 might exert its inflammatory effects also through inflammasome-induced caspase-1 activation.

extracellular Hsp70, caspases, THP-1 cells

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