The online version of this article (https://doi.org/10.1186/s13058-018-1036-5) contains supplementary material, which is available to authorized users.
Antimicrobial T cells play key roles in the disease progression of cancers arising in mucosal epithelial tissues, such as the colon. However, little is known about microbe-reactive T cells within human breast ducts and whether these impact breast carcinogenesis.
Epithelial ducts were isolated from primary human breast tissue samples, and the associated T lymphocytes were characterized using flow cytometric analysis. Functional assays were performed to determine T-cell cytokine secretion in response to bacterially treated human breast carcinoma cells.
We show that human breast epithelial ducts contain mucosal associated invariant T (MAIT) cells, an innate T-cell population that recognizes specific bacterial metabolites presented by nonclassical MR1 antigen-presenting molecules. The MAIT cell population from breast ducts resembled that of peripheral blood in its innate lymphocyte phenotype (i.e., CD161, PLZF, and interleukin [IL]-18 receptor coexpression), but the breast duct MAIT cell population had a distinct T-cell receptor Vβ use profile and was markedly enriched for IL-17-producing cells compared with blood MAIT cells. Breast carcinoma cells that had been exposed to Escherichia coli activated MAIT cells in an MR1-dependent manner. However, whereas phorbol 12-myristate 13-acetate/ionomycin stimulation induced the production of both interferon-γ and IL-17 by breast duct MAIT cells, bacterially exposed breast carcinoma cells elicited a strongly IL-17-biased response. Breast carcinoma cells also showed upregulated expression of natural killer group 2 member D (NKG2D) ligands compared with primary breast epithelial cells, and the NKG2D receptor contributed to MAIT cell activation by the carcinoma cells.
These results demonstrate that MAIT cells from human breast ducts mediate a selective T-helper 17 cell response to human breast carcinoma cells that were exposed to E. coli. Thus, cues from the breast microbiome and the expression of stress-associated ligands by neoplastic breast duct epithelial cells may shape MAIT cell responses during breast carcinogenesis.
Additional file 1: Figure S4. Magnetic sorting of CD161+ cells from PBMCs yields enrichment of MAIT cells and depletion of nonlymphocytic antigen-presenting cells. Flow cytometric analysis of the CD161-enriched fraction, showing the MAIT cell population (far right plot) and demonstrating that the CD3− population is almost entirely comprised of NK cells as assessed by NKp46 and CD56 expression. (PDF 235 kb)13058_2018_1036_MOESM1_ESM.pdf
Additional file 2: Figure S1. Validation of MR1 tetramer staining. MR1-5RU tetramer staining (1:100 dilution) and MR1-6FP tetramer (1:100 dilution) in combination with Vα7.2 on CD3+ cells from (a) PBMCs and (b) breast ducts. (PDF 401 kb)13058_2018_1036_MOESM2_ESM.pdf
Additional file 3: Figure S2. Phenotypic analyses of breast duct lymphocytes. a CD161, IL-18Rα, and PLZF expression on Vα7.2+ T cells that do not costain with MR1-5RU tetramer (black line) compared with Vα7.2−CD3+ T cells (filled gray histogram). b In contrast to most T cells from PBMCs, T lymphocytes from breast ducts show a tissue-resident memory phenotype (CD69+ and CD103+). (PDF 270 kb)13058_2018_1036_MOESM3_ESM.pdf
Additional file 4: Figure S3. IFN-γ vs. IL-17A production by in vitro-expanded MAIT lines after PMA/ionomycin stimulation. In vitro-expanded MAIT cells derived from breast duct (left column) or from PBMCs (right column) were stimulated with PMA and ionomycin, and expression of IFN-γ and IL-17A was assessed by intracellular cytokine staining. (PDF 252 kb)13058_2018_1036_MOESM4_ESM.pdf
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- Mucosal associated invariant T cells from human breast ducts mediate a Th17-skewed response to bacterially exposed breast carcinoma cells
Nicholas A. Zumwalde
Jill D. Haag
Michael N. Gould
Jenny E. Gumperz
- BioMed Central
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