Human lung epithelial cells contain Mycobacterium tuberculosis in a late endosomal vacuole and are efficiently recognized by CD8⁺ T cells.
Mycobacterium tuberculosis (Mtb) is transmitted via inhalation of aerosolized particles. While alveolar macrophages are thought to play a central role in the acquisition and control of this infection, Mtb also has ample opportunity to interact with the airway epithelium. In this regard, we have recently shown that the upper airways are enriched with a population of non-classical, MR1-restricted, Mtb-reactive CD8⁺ T cells (MAIT cells). Additionally, we have demonstrated that Mtb-infected epithelial cells lining the upper airways are capable of stimulating IFNγ production by MAIT cells. In this study, we demonstrate that airway epithelial cells efficiently stimulate IFNγ release by MAIT cells as well as HLA-B45 and HLA-E restricted T cell clones. Characterization of the intracellular localization of Mtb in epithelial cells indicates that the vacuole occupied by Mtb in epithelial cells is distinct from DC in that it acquires Rab7 molecules and does not retain markers of early endosomes such as Rab5. The Mtb vacuole is also heterogeneous as there is a varying degree of association with Lamp1 and HLA-I. Although the Mtb vacuole shares markers associated with the late endosome, it does not acidify, and the bacteria are able to replicate within the cell. This work demonstrates that Mtb infected lung epithelial cells are surprisingly efficient at stimulating IFNγ release by CD8⁺ T cells.
Portland Veterans Administration Medical Center, Portland, Oregon, United States of America; Department of Pulmonary and Critical Care Medicine, Oregon Health & Sciences University, Portland, Oregon, United States of America.
Melanie J
MJ
Harriff
Department of Pediatrics, Oregon Health & Sciences University, Portland, Oregon, United States of America.
Meghan E
ME
Cansler
Department of Pediatrics, Oregon Health & Sciences University, Portland, Oregon, United States of America.
Katelynne Gardner
KG
Toren
Department of Pulmonary and Critical Care Medicine, Oregon Health & Sciences University, Portland, Oregon, United States of America.
Elizabeth T
ET
Canfield
Department of Pulmonary and Critical Care Medicine, Oregon Health & Sciences University, Portland, Oregon, United States of America.
Stephen
S
Kwak
Portland Veterans Administration Medical Center, Portland, Oregon, United States of America; Department of Pulmonary and Critical Care Medicine, Oregon Health & Sciences University, Portland, Oregon, United States of America; Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, United States of America.
Marielle C
MC
Gold
Portland Veterans Administration Medical Center, Portland, Oregon, United States of America; Department of Pulmonary and Critical Care Medicine, Oregon Health & Sciences University, Portland, Oregon, United States of America; Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, United States of America.
David M
DM
Lewinsohn
D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D002460:Cell Line; D018920:Coculture Techniques; D011992:Endosomes / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D004847:Epithelial Cells / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D015870:Gene Expression; D015235:HLA-B Antigens / Q000235:genetics / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D051907:Lysosomal Membrane Proteins / Q000235:genetics / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D061251:Primary Cell Culture; D020545:Respiratory Mucosa / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D014617:Vacuoles / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000276:immunology; D000090802:rab7 GTP-Binding Proteins; D000097625:HLA-E Antigens; D052118:Lysosomal-Associated Membrane Protein 1
D015235:HLA-B Antigens; D015395:Histocompatibility Antigens Class I; D007371:Interferon-gamma; D051907:Lysosomal Membrane Proteins; D020691:rab GTP-Binding Proteins; D000090802:rab7 GTP-Binding Proteins; D000097625:HLA-E Antigens; C077377:HLA-B45 antigen; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1; C000716463:rab7 GTP-binding proteins, human