"A peptide derived from chaperonin 60.1, IRL201104, inhibits LPS-induced acute lung inflammation": Effect of IRL201104 on lung inflammation

Chaperonin 60.1 (Cpn60.1) is a protein derived from M. tuberculosis that has been shown, along with its peptide fragment IRL201104, to have beneficial effects in models of allergic inflammation. To further investigate the anti-inflammatory properties of Cpn60.1 and IRL201104, we have investigated these molecules in a model of non-allergic lung inflammation. Mice were treated with Cpn60.1 (0.5-5000 ng/kg) or IRL201104 (0.00025-2.5 ng/kg), immediately before intranasal instillation of bacterial lipopolysaccharide (LPS). Cytokine levels and cell numbers in mouse bronchoalveolar lavage (BAL) fluid were measured 4h after LPS administration. In some experiments mice were depleted of lung-resident phagocytes. Cells from BAL fluid were analysed for inflammasome function. Human umbilical vein endothelial cells (HUVEC) were analysed for adhesion molecule expression. Human neutrophils were analysed for integrin expression, chemotaxis and cell polarisation. Cpn60.1 and IRL201104 significantly inhibited neutrophil migration into the airways, independently of route of administration. This effect of the peptide was absent in TLR4 and Annexin A1 knock-out mice. Intravital microscopy revealed that IRL201104 reduced leukocyte adhesion and migration into inflamed tissues. However, IRL201104 did not significantly affect adhesion molecule expression in HUVEC or integrin expression, chemotaxis or polarisation of human neutrophils at the studied concentrations. In phagocyte-depleted animals, the anti-inflammatory effect of IRL201104 was not significant. IRL201104 significantly reduced IL-1β and NLRP3 expression and increased A20 expression in BAL cells. This study shows that Cpn60.1 and IRL201104 potently inhibit LPS-induced neutrophil infiltration in mouse lungs by a mechanism dependent on tissue-resident phagocytes and to a much lesser extent, the pro-resolving factor Annexin A1.