Transcription Factor Analysis to Investigate Immunosenescence in Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA) is linked to various signs of advanced aging, such as premature immunosenescence which occurs due to decline in regenerative ability of T cells. RA T cells develop a unique aggressive inflammatory senescent phenotype with an imbalance of Th17/T regulatory (Treg) cell homeostasis and presence of CD28^- T cells. The phenotypic analysis and characterization of T cell subsets become necessary to ascertain if any functional deficiencies exist within with the help of transcription factor (TF) analysis. These subset-specific TFs dictate the functional characteristics of T-cell populations, leading to the production of distinct effector cytokines and functions. Examining the expression, activity, regulation, and genetic sequence of TFs not only aids researchers in determining their importance in disease processes but also aids in immunological monitoring of patients enrolled in clinical trials, particularly in evaluating various T-cell subsets [Th17 (CD3⁺CD4⁺IL17⁺RORγt⁺) cells and T regulatory (Treg) (CD3⁺CD4⁺CD25⁺CD127^-FOXP3⁺) cells], markers of T-cell aging [aged Th17 cells (CD3⁺CD4⁺IL17⁺RORγt⁺CD28^-), and aged Treg cells (CD3⁺CD4⁺CD25⁺CD127^-FOXP3⁺CD28^-)]. In this context, we propose and outline the protocols for assessing the expression of TFs in aged Th17 and Treg cells, highlighting the crucial aspects of this cytometric approach.