2019 Fiscal Year Annual Research Report
Elucidation of the cause of allergy by identifying somatic mutations in human IgE+ memory B cells.
| Project/Area Number |
18K16162
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| Research Institution | National Center for Global Health and Medicine |
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Principal Investigator |
NguyenTien Dat 国立研究開発法人国立国際医療研究センター, その他部局等, 上級研究員 (50750270)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Keywords | Allergy / B cells / IgE |
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| Outline of Annual Research Achievements |
It has been largely unknown how IgE production is regulated and how IgE B-cell memory is generated in allergic patients. However, there are technical limitations in identifying rare IgE+ B cells, especially in humans. Adopting the Fas-mediated Ag-specific iGB cell selection (FAIS) system, I have developed a system to selectively expand IgE+ B cells by a four-step B cell culture procedure. 1) Culture with IL-21 on feeder cells expressing exogenous CD40L and BAFF (40LB). 2) Stimulation culture on 40LB cells expressing FcεR1 to stimulate IgE+ iGB cells. 3) Selection culture on 40LB cells expressing the Fas ligand: all but IgE+ iGB cells undergo apoptosis. 4) Recovery culture on 40LB cells. Starting with blood B cells of hay fever allergic donors, I successfully obtained an almost pure population of IgE+ B cells with this procedure in combination with cell sorting. I found 30 mutations in genomic genes of mIgE+ Bm cells by comparing with non-B leukocytes from the same patients of various allergic diseases, using whole-exome sequencing. The mutant genes mainly express on the membrane and the endoplasmic reticulum. Their functions are cell-cell interaction, ER stress, apoptosis, cell proliferation, endocytosis, and ubiquitination. Especially, I found that allergic IgE+ B cells have IgE-endocytosis defects. Altogether, the mutations in endocytosis-related genes (LRP6, MICALL1, EPS15, and ACK1) may lead to the survival of allergic IgE+ B cells then the allergic disease.
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