Mrp1 is involved in lipid presentation and iNKT cell activation by Streptococcus pneumoniae

Shilpi Chandra,Stewart K Richardson,Bjoern Peters,Steven A Porcelli,Sonia Sharma,Zheng Fu,Archana Khurana,Catherine M Crosby,Meng Zhao,James Gray,Gurdyal Besra,Mitchell Kronenberg,Ashu Chawla,William B Kiosses,Natacha Veerapen,Kaori Hitomi,Amy R Howell

doi:10.1038/s41467-018-06646-8

Abstract

Invariant natural killer T cells (iNKT cells) are activated by lipid antigens presented by CD1d, but the pathway leading to lipid antigen presentation remains incompletely characterized. Here we show a whole-genome siRNA screen to elucidate the CD1d presentation pathway. A majority of gene knockdowns that diminish antigen presentation reduced formation of glycolipid-CD1d complexes on the cell surface, including members of the HOPS and ESCRT complexes, genes affecting cytoskeletal rearrangement, and ABC family transporters. We validated the role in vivo for the multidrug resistance protein 1 (Mrp1) in CD1d antigen presentation. Mrp1 deficiency reduces surface clustering of CD1d, which decreased iNKT cell activation. Infected Mrp1 knockout mice show decreased iNKT cell responses to antigens from Streptococcus pneumoniae and were associated with increased mortality. Our results highlight the unique cellular events involved in lipid antigen presentation and show how modification of this pathway can lead to lethal infection.

Highlights

Invariant natural killer T cells are activated by lipid antigens presented by CD1d, but the pathway leading to lipid antigen presentation remains incompletely characterized
Recognition of GalGalCer requires that CD1d localize to late endosomes/lysosomes, where antigen loading takes place[10]
The use of this antigen allowed us to assess effects on various processes leading to iNKT cell stimulation, including antigen uptake, traffic in antigen-presenting cells (APCs) to lysosomes, carbohydrate processing, CD1d trafficking to lysosomes, antigen loading, and movement of CD1d-lipid antigen complexes to the cell surface

Summary

Introduction

Invariant natural killer T cells (iNKT cells) are activated by lipid antigens presented by CD1d, but the pathway leading to lipid antigen presentation remains incompletely characterized. In order to obtain a more comprehensive understanding of the pathway leading to lipid antigen presentation by CD1d, we performed a genome-wide small interfering RNA (siRNA) screen in a mouse macrophage cell line loaded with a glycolipid antigen that requires lysosomal carbohydrate removal for its presentation[10]. In this way, we set out to identify genes related to how glycolipid antigens are taken up by antigen-presenting cells (APCs), processed, and loaded into CD1d. We show that Abcc[1], an ATP transporter, affects CD1d clustering and localization to lipid membrane rafts and is involved in lipid presentation and the protective antibacterial response of iNKT cells

Methods

Results

Conclusion