Reconstitution of Monocyte Subsets and PD-L1 Expression but Not T Cell PD-1 Expression in Obstructive Sleep Apnea Patients upon PAP Therapy

Int J Mol Sci. 2021 Oct 21;22(21):11375. doi: 10.3390/ijms222111375.


Obstructive sleep apnea (OSA) is characterized by nocturnal breathing intermissions resulting in oxidative stress and eventually, a low-grade systemic inflammation. The study aimed to investigate the impact of positive airway pressure (PAP) therapy on the inflammatory milieu as measured by monocyte and T cell phenotypic alterations. Participants were assessed for their OSA severity before PAP therapy and about six months later, including patient-reported outcome and therapy usage by telemetry readout. The distributions of the CD14/CD16-characterized monocyte subsets as well as the CD4/CD8-characterized effector T cell subsets with regard to their PD-1 and PD-L1 expression were analyzed by flow cytometry from blood samples. Data of 25 patients revealed a significant reconstitution of the monocyte subset distribution and a decrease in PD-L1 expression on pan-monocytes and CD8+ T cells without an association to initial AHI and overweight. The PD-1 expression was still increased on T cell subsets, especially on CD4+ TH17/22 cells. We conclude that PAP therapy might have a rapid effect on the monocyte phenotype and overall PD-L1 expression levels. However, T cell immune alterations especially on TH17/22 cells persist longer, indicating an ongoing disturbance of the adaptive immune system.

Keywords: PAP therapy; PD-1/PD-L1; monocyte subsets; obstructive sleep apnea.

MeSH terms

  • B7-H1 Antigen / genetics*
  • CD4-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / metabolism
  • GPI-Linked Proteins
  • Gene Expression Regulation
  • Humans
  • Inflammation*
  • Lipopolysaccharide Receptors
  • Monocytes / metabolism*
  • Oxidative Stress
  • Positive-Pressure Respiration*
  • Programmed Cell Death 1 Receptor / genetics
  • Receptors, IgG
  • Sleep Apnea, Obstructive / immunology*
  • Sleep Apnea, Obstructive / metabolism
  • Sleep Apnea, Obstructive / therapy


  • B7-H1 Antigen
  • CD14 protein, human
  • CD274 protein, human
  • FCGR3B protein, human
  • GPI-Linked Proteins
  • Lipopolysaccharide Receptors
  • Programmed Cell Death 1 Receptor
  • Receptors, IgG