Bronchiolitis obliterans syndrome is associated with increased p-glycoprotein expression and loss of glucocorticoid receptor from steroid-resistant proinflammatory CD8+ T cells

Abstract

Immunosuppressive therapy fails to suppress the production of proinflammatory cytokines, particularly by CD8 T cells, in stable lung transplant recipients and those undergoing chronic rejection, suggesting that some patients may become relatively resistant to immunosuppressants such as glucocorticoids (GC). We have shown loss of GC receptor (GCR) from the CD8 cells, and we hypothesized that the drug membrane efflux pump, p-glycoprotein-1 (Pgp), may also be involved in lymphocyte steroid resistance following lung transplant. Pgp/GCR expression and interferon (IFN)-γ/tumour necrosis factor (TNF)-α proinflammatory cytokine production was measured in blood lymphocytes from 15 stable lung transplant patients, 10 patients with bronchiolitis obliterans syndrome (BOS) and 10 healthy aged-matched controls (± prednisolone ± Pgp inhibitor, cyclosporin A ± GCR activator, Compound A) using flow cytometry. Both Pgp and Pgp lymphocyte subsets from all subjects produced IFN-γ/TNF-α proinflammatory cytokines. Pgp expression was increased in CD8 Pgp T cells and correlated with IFN-γ/TNF-α expression and BOS grade. Reduced GCR was observed in CD8 Pgp T, natural killer (NK) T-like and NK cells from stable patients compared with controls, and reduced further in CD8 Pgp T cells in BOS. The addition of 2·5 ng/ml cyclosporin A and 1 µM prednisolone inhibit IFN-γ/TNF-α production significantly by CD8 Pgp T cells from BOS patients. The addition of 10 µM Compound A and 1 µM prednisolone inhibit IFN-γ/TNF-α production significantly by CD8 Pgp T cells from BOS patients. BOS is associated with increased Pgp expression and loss of GCR from steroid-resistant proinflammatory CD8 T cells. Treatments that inhibit Pgp and up-regulate GCR in CD8 T cells may improve graft survival.

Therapeutic Targeting Steroid Resistant Pro-Inflammatory NK and NKT-Like Cells in Chronic Inflammatory Lung Disease

“…Furthermore, the dose of cyclosporine A required to inhibit Pgp1 was 2.5 ng/mL, which is approximately 25 times less than the dose used to treat transplant rejection so not considered to be associated with any unwanted side effects. There has been a very recent report on Pgp1 expression in lymphocyte subsets in patients with BOS [18]. Pgp1 expression was increased in CD8+Pgp+ T cells and correlated with IFNγ/TNFα expression along with the BOS grade [18].…”

“…There has been a very recent report on Pgp1 expression in lymphocyte subsets in patients with BOS [18]. Pgp1 expression was increased in CD8+Pgp+ T cells and correlated with IFNγ/TNFα expression along with the BOS grade [18]. However, Pgp1 expression was decreased in NKT-like and NK lymphocyte subsets in patients with BOS compared with heathy aged-matched control subjects suggesting alternate mechanisms of steroid resistance in these patients [18].…”

“…These data suggests that alternate treatment options to glucocorticoids are required to suppress pro-inflammatory cytokines in these patients. Reduced GCR has been reported in CD8+NKT-like and NK cells from stable lung transplant patients and patients with BOS compared with controls [18]. Another study of patients with interstitial lung disease showed decreased expression of GCR mRNA in lung tissue from steroid resistant compared with steroid sensitive patients [24].…”

“…Steroid resistance was shown to be similarly increased in patients with BOS compared with stable transplant patients and in stable patients compared with healthy aged-matched control subjects as assessed by the decreased inhibitory effect of 1 µM prednisolone on IFNγ and TNFα production by CD8+ T cells [18]. Unfortunately, NKT-like and NK cells were not assessed.…”