In this work of the University Institute of Biotechnology and Biomedicine (BIOTECMED) and the Department of Microbiology and Ecology of the UV, a model of vaccination in mice with a non-virulent strain of the fungus Candida albicans has been used, and demonstrated the protective capacity against future infections independently of specific immunity (development of T lymphocytes and B lymphocytes producing antibodies specific for the pathogen).

“What we see is that vaccination trains stem cells and hematopoietic progenitors in the bone marrow and then travels to the spleen, where they are able to produce large amounts of improved mature cells to fight infection”, explains Alberto Yáñez, Ramon y Cajal researcher at the UV and director of this work.

“In previous studies, our group showed that these cells are able to directly detect the opportunistic pathogenic fungus C. albicans and respond by producing a greater number of innate immune system cells, important for eliminating the fungus. In addition, we observed that the function of these cells was improved to fight the infection”, indicates María Luisa Gil, professor of the Department of Microbiology and Ecology of the UV and co-author of the study.

To find the action mechanism of the vaccine on this training, state-of-the-art technology has been used consisting of RNA sequencing of individual cells. With this, it is possible to determine the changes in gene expression that each of these stem cells undergo during vaccination and the response to an infection with a virulent strain of the fungus. This analysis has pointed to the growth factor GM-CSF (a type of hormone-like substance that helps the bone marrow produce new blood cells and is created during vaccination), as responsible for programming the cells. Stem cells and hematopoietic progenitors to increase their protective capacity.

“The results of this study highlight the importance of stem cells and hematopoietic progenitors in the protective immune response to infections”, said Cristina Bono, the first author of the article and a UV predoctoral researcher. “In addition, these results could help design more effective immunotherapies in the future, including the development of enhanced vaccines, to enhance the immune response to various infections, including COVID-19”, says Alberto Yáñez.

This work has the collaboration of Nathan Salomonis and Lee Grimes, researchers in haematology and bioinformatics at Cincinnati Children’s Hospital Medical Center in Cincinnati (USA). The work has been funded by the Ministry of Science and Innovation (RTI2018-093426-B-I00).

Article: Bono C, Guerrero P, Jordán-Pla A, Erades A, Salomonis N, Grimes HL, Gil ML and Yáñez A (2021) GM-CSF «Programs Hematopoietic Stem and Progenitor Cells During Candida albicans Vaccination for Protection Against Reinfection». Front. Immunol. 12:790309. doi: 10.3389/fimmu.2021.790309

Link: https://www.frontiersin.org/articles/10.3389/fimmu.2021.790309/abstract