α-Lactosylceramide Protects Against iNKT-Mediated Murine Airway Hyperreactivity and Liver Injury Through Competitive Inhibition of Cd1d Binding.

Alan Chuan-Ying Lai,Hsien-Neng Kao,Po-Yu Chi,Jacquelyn Gervay-Hague,Ya-Jen Chang,Yun-Chiann Han,Christina Li-Ping Thio,Hsiao-Wu Hsieh

doi:10.3389/fchem.2019.00811

Alan Chuan-Ying Lai, Hsien-Neng Kao + Show 6 more

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https://doi.org/10.3389/fchem.2019.00811

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Abstract

Invariant natural killer T (iNKT) cells, which are activated by T cell receptor (TCR)-dependent recognition of lipid-based antigens presented by the CD1d molecule, have been shown to participate in the pathogenesis of many diseases, including asthma and liver injury. Previous studies have shown the inhibition of iNKT cell activation using lipid antagonists can attenuate iNKT cell-induced disease pathogenesis. Hence, the development of iNKT cell-targeted glycolipids can facilitate the discovery of new therapeutics. In this study, we synthesized and evaluated α-lactosylceramide (α-LacCer), an α-galactosylceramide (α-GalCer) analog with lactose substitution for the galactose head and a shortened acyl chain in the ceramide tail, toward iNKT cell activation. We demonstrated that α-LacCer was a weak inducer for both mouse and human iNKT cell activation and cytokine production, and the iNKT induction by α-LacCer was CD1d-dependent. However, when co-administered with α-GalCer, α-LacCer inhibited α-GalCer-induced IL-4 and IFN-γ production from iNKT cells. Consequently, α-LacCer also ameliorated both α-GalCer and GSL-1-induced airway hyperreactivity and α-GalCer-induced neutrophilia when co-administered in vivo. Furthermore, we were able to inhibit the increases of ConA-induced AST, ALT and IFN-γ serum levels through α-LacCer pre-treatment, suggesting α-LacCer could protect against ConA-induced liver injury. Mechanistically, we discerned that α-LacCer suppressed α-GalCer-stimulated cytokine production through competing for CD1d binding. Since iNKT cells play a critical role in the development of AHR and liver injury, the inhibition of iNKT cell activation by α-LacCer present a possible new approach in treating iNKT cell-mediated diseases.

Highlights

Invariant natural killer T cells are a rare subset of T cells that possess properties of both conventional T and natural killer (NK) cells (Wu and Van Kaer, 2011; Cameron et al, 2015)
Unlike conventional T cells, Invariant natural killer T (iNKT) cells express a highly restricted T cell receptor (TCR)-α chain (Vα14/Jα18 in mice and Vα24/Jα18 in humans) and a moderately diverse TCR-β chain (Vβ2, Vβ7, α-Lactosylceramide Suppresses iNKT-Mediated Inflammation and Vβ8 in mice and Vβ11 in humans; Carreno et al, 2016). iNKT cells are activated through invariant TCR by the recognition of lipid-based antigens presented by the MHC class I-like CD1d molecule found on antigen presenting cells (Laurent et al, 2014; Cameron et al, 2015)
INKT cells play a key role in bridging the innate and adaptive immunity. Due to their restricted TCR rearrangements, all iNKT cells share the ability to recognize glycolipids with their sugar head attached in an α-anomeric configuration to the polar head group of a lipid (Kjer-Nielsen et al, 2006). α-galactosylceramide, known as KRN7000, is the prototypical glycolipid of this type and has the capability to activate all iNKT cells with a mixed Th1 and Th2 response when presented by CD1d molecule (Kawano et al, 1997; Zhang et al, 2008). α-Glucuronosylceramide (GSL-1), a glycolipid extracted from Sphingomonas bacteria, represents another CD1d ligand with αlinked glucuronic acid and a mixture of at least three different sphingosine bases (Perola et al, 2002; Kinjo et al, 2005)

Summary

INTRODUCTION

Invariant natural killer T (iNKT) cells are a rare subset of T cells that possess properties of both conventional T and natural killer (NK) cells (Wu and Van Kaer, 2011; Cameron et al, 2015). Activated iNKT cells can enhance tumor immunity (Kawano et al, 1999; Aspeslagh et al, 2013) as well as suppress autoimmune disease (Singh et al, 2001) They are associated with the disruption of mucosal homeostasis in the intestines and airways (Nau et al, 2014) and contribute to allergic airway inflammation in various allergen models, including ovalbumin (OVA) and house dust mite (HDM) extract, through Th2-biased cytokine responses (Akbari et al, 2003; Lisbonne et al, 2003; Wingender et al, 2011). Our results in the plate-bound CD1d binding assay suggested the inhibitory function of α-LacCer was mediated by competitive CD1d binding

MATERIALS AND METHODS

RESULTS

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