Effects of extracellular Hsp70, lipoteichoic acid and lipopolysaccharide on TLR2 and TLR4 mRNA expression in monocyte-derived macrophages

Abstract

Introduction: Patients with chronic obstructive pulmonary disease (COPD) are prone to bacterial colonizations and infections. They have elevated extracellular Hsp70 (eHsp70) in plasma, which exerts its biological actions via Toll-like receptors (TLR) 2 and 4 leading to the development of inflammation. Aims and Objectives: The aim of this study was to explore the effects of eHsp70 alone and in combination with bacterial components lipoteichoic acid (LTA) and lipopolysaccharide (LPS) on TLR2 and TLR4 mRNA expression in monocyte-derived macrophages (MDMs). Methods: MDMs were treated with recombinant human Hsp70 (rhHsp70), LPS, LTA, and their combinations for 24 h. RNA was isolated by Trizol/chlorophorm method, cDNA was synthesized followed by qPCR. Results: 3 and 10 µg/ml rhHsp70 alone, as well as 0.1 µg/ml LPS and 1 µg/ml LTA increased TLR2 expression compared to non-treated MDMs. Combinations of 1 µg/ml rhHsp70 with LPS or LTA increased, while combinations with 3 µg/ml rhHsp70 did not affect TLR2 expression. In contrast, LPS, LTA and their combinations with rhHsp70 decreased TLR4 expression compared to non-treated MDMs. Treatment of the cells with rhHsp70 alone did not change TLR4 expression. Conclusions: Pro-inflammatory effect in MDMs could be potentiated by rhHsp70, LPS and LTA via elevated TLR2 expression. It seems that rhHsp70 does not have an effect on TLR4 expression in MDMs, but LPS, LTA and their combinations with rhHsp70 supress it. This might lead to altered capacity to properly respond to the noxious stimuli, such as bacteria or viruses, thus leading to adverse consequences for patients with COPD.