Conclusion
PF-06651600 demonstrated a potential to modulate the activity of TCD4+ cells in RA patients and to reduce the commitment of Th cells to the pathogenic Th1 and Th17 subsets. Further, it caused TCD4+ cells to gain an exhausted phenotype which is associated with better prognosis in RA patients.
Results
RA patients had higher percentages of TCD4+ cells, CD4+ PD-1+ cells, and CD4+ PD-1+ TIGIT+ cells compared to a healthy control group and the TCD4+ cells of these patients showed higher interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and interleukin (IL)-17 secretion along with higher messenger RNA (mRNA) expressions of T-bet. The percentage of CD4+ PD-1+ TIGIT+ cells showed a reverse correlation with the Disease Activity Score of 28 joints of the RA patients. PF-06651600 caused a significant decrease in the mRNA expressions of T-bet and RAR-related orphan receptor γt and the secretion of interferon (IFN)-γ and TNF-α in TCD4+ cells of RA patients. On the other hand, the population of CD4+ PD-1+ TIGIT+ cells was expanded under the influence of PF-06651600. This treatment also reduced the proliferation of TCD4+ cells.