Age-Associated Differences in MiRNA Signatures Are Restricted to CD45RO Negative T Cells and Are Associated with Changes in the Cellular Composition, Activation and Cellular Ageing.

Nato Teteloshvili,Anke Van Den Berg,Joost Kluiver,Bart-Jan Kroesen,Elisabeth Brouwer,Kornelis S M Van Der Geest,Roelof Jan Van Der Lei,Pytrick Jellema,Graham Pawelec,Annemieke M H Boots,Bernard Mari

doi:10.1371/journal.pone.0137556

Abstract

MicroRNAs (miRNAs) have emerged as important players in the regulation of T-cell functionality. However, comprehensive insight into the extent of age-related miRNA changes in T cells is lacking. We established miRNA expression patterns of CD45RO- naïve and CD45RO+ memory T-cell subsets isolated from peripheral blood cells from young and elderly individuals. Unsupervised clustering of the miRNA expression data revealed an age-related clustering in the CD45RO- T cells, while CD45RO+ T cells clustered based on expression of CD4 and CD8. Seventeen miRNAs showed an at least 2-fold up- or downregulation in CD45RO- T cells obtained from young as compared to old donors. Validation on the same and independent samples revealed a statistically significant age-related upregulation of miR-21, miR-223 and miR-15a. In a T-cell subset analysis focusing on known age-related phenotypic changes, we showed significantly higher miR-21 and miR-223 levels in CD8+CD45RO-CCR7- TEMRA compared to CD45RO-CCR7+ TNAIVE-cells. Moreover, miR-21 but not miR-223 levels were significantly increased in CD45RO-CD31- post-thymic TNAIVE cells as compared to thymic CD45RO-CD31+ TNAIVE cells. Upon activation of CD45RO- TNAIVE cells we observed a significant induction of miR-21 especially in CD4+ T cells, while miR-223 levels significantly decreased only in CD4+ T cells. Besides composition and activation-induced changes, we showed a borderline significant increase in miR-21 levels upon an increasing number of population doublings in CD4+ T-cell clones. Together, our results show that ageing related changes in miRNA expression are dominant in the CD45RO- T-cell compartment. The differential expression patterns can be explained by age related changes in T-cell composition, i.e. accumulation of CD8+ TEMRA and CD4+ post-thymic expanded CD31- T cells and by cellular ageing, as demonstrated in a longitudinal clonal culture model.

Highlights

Advanced age has been associated with defects of the immune system to mount appropriate antigen specific responses to pathogens
Human T-cell clones are characterized by altered cell surface and cytokine expression signatures that resemble the in vivo situation of chronic antigenic stress
In the CD45RO- T cell subset, the clustering was based on age, irrespective of CD4 and CD8 expression status (Fig 1A)

Summary

Introduction

Advanced age has been associated with defects of the immune system to mount appropriate antigen specific responses to pathogens. Within the CD8+ T cell fraction, expression of CD45RA or CD45RO in combination with the C-C chemokine receptor type 7 (CCR7) is used to further define CCR7+CD45RA+(CD45RO-) naïve (TNAIVE), CCR7+CD45RA-(CD45RO+) central memory (TCM), CCR7-CD45RA-(CD45RO+) effector memory (TEM) and CCR7-CD45RA+(CD45RO)- late-stage effector memory (TEMRA) T-cell subsets [2]. Whether or not this model can be applied to the CD4+ subset is still a matter of debate. Long-term cultured T-cell clones may represent a model for cellular ageing [10]

Methods

Results

Discussion

Conclusion