title: Cell division curtails helper phenotype plasticity and expedites helper T-cell differentiation.
abstract: Following activation by antigen, helper T cells differentiate into one of many effector phenotypes. Formulating mechanistic mathematical models combining regulatory networks at the transcriptional, translational and epigenetic level, we study how individual helper T cells may adopt their different phenotypes. For each cytokine phenotype, for example, T helper type 1 (Th1) and type 2 (Th2) cells, we find that the intracellular molecular network allows a cell to adopt one of the three states, which we interpret as naive, active and memory states. Cell division markedly speeds up the differentiation into a particular memory state because of DNA demythelation. In a memory state, cells readily resume production of the same cytokine they produced before. Using stochastic models we show that helper T-cell plasticity (that is, the ability to switch phenotype) is low during clonal expansion. Although most memory cells rapidly secrete the original cytokine upon restimulation, some adopt another phenotype and produce different cytokines, allowing for considerable diversity in the phenotypes that are adopted during a memory response. In summary, we show that helper T-cell division expedites cell differentiation by increasing DNA demethylation. We also show that plasticity is low during the clonal expansion phase, but that helper T cells may adopt alternative phenotypes during a memory response.
authors.affiliation: Theoretical Biology and Bioinformatics, Utrecht University, Utrecht, The Netherlands. h.j.vandenham@erasmusmc.nl
authors.forename: Henk Jan
authors.initials: HJ
authors.lastname: van den Ham
authors.forename: Rob J
authors.initials: RJ
authors.lastname: de Boer
mesh_terms: D000465:Algorithms; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology*; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D003198:Computer Simulation; D018899:CpG Islands / Q000235:genetics / Q000276:immunology; D016207:Cytokines / Q000235:genetics / Q000276:immunology*; D019175:DNA Methylation / Q000276:immunology; D053263:Gene Regulatory Networks / Q000235:genetics / Q000276:immunology; D006801:Humans; D008957:Models, Genetic; D018448:Models, Immunological; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism
chemical_list: D016207:Cytokines