Expression of programmed cell death-1 and its ligand B7 homolog 1 in peripheral blood lymphocytes from patients with peripartum cardiomyopathy

Immune response has been postulated to play a prominent role in the pathogenesis of peripartum cardiomyopathy (PPCM). Given the importance of programmed death (PD)-1 and its ligand B7 homologue 1 (B7-H1) costimulatory molecules as an immune regulatory pathway, this study aimed to investigate the effect of PD-1 and B7-H1 expression on immune response in peripheral blood lymphocytes from the patients with PPCM. Hypothesis: PD-1 and B7-H1 may be involved in modulating immune response in PPCM.

This study provided the first findings that PD-1 and B7-H1 expression were decreased, which might impair functional regulation of negative costimulation on immune response that may work in the etiopathogenesis of PPCM.

Peripheral blood lymphocytes were obtained from PPCM and pregnancy-matched healthy women. PD-1 and B7-H1 expression were determined using fluorescence quantitative reverse transcription-polymerase chain reactions (RT-PCR) and Western blot. The presence of serum interferon (IFN)-γ and interleukin (IL)-4 were determined with enzyme-linked immunosorbent assay.

The levels of pro-brain natriuretic peptide and IFN-γ were markedly elevated, whereas the levels of left ventricular ejection fraction and IL-4 were significantly reduced in PPCM patients compared to controls. Additionally, both RT-PCR and Western blot revealed that the levels of PD-1 and B7-H1 expression were decreased significantly in PPCM patients compared with controls. A significant positive correlation was observed between PD-1 and B7-H1 expression. Furthermore, PD-1 and B7-H1 expression showed significant negative correlation with IFN-γ, as well as positive correlation with IL-4. Therefore, decreased expression of PD-1 and B7-H1 led to a dysregulating immune response such that cellular immunity linked to T helper (Th)1 cells was predominant over humoral immunity linked to Th2 cells in PPCM. Conclusions: This study provided the first findings that PD-1 and B7-H1 expression were decreased, which might impair functional regulation of negative costimulation on immune response that may work in the etiopathogenesis of PPCM.