Reduced expression of peroxisome proliferator-activated receptor alpha in BAL and blood T cells of non-löfgren's sarcoidosis patients.

BACKGROUND

Sarcoidosis is a granulomatous disease affecting in particular the lungs. The peroxisome proliferator-activated receptors (PPARs) play important regulatory roles in inflammation. The aim of this study was to gain more insight about the expression of all three PPARs (α, β/δ and γ) in sarcoidosis.

METHODS

Bronchoalveolar lavage (BAL) cells and peripheral blood cells were obtained from healthy controls (HC) and sarcoidosis patients with Löfgren's syndrome (LS) and without Löfgren's syndrome (non-LS). PPARs mRNA expression was analyzed in total BAL cells and in FACS (Fluorescence-activated cell sorting) sorted alveolar macrophages (AM) and CD4(+) T cells respectively by comparative RT-PCR. PPARs protein expression was analyzed in AM, and in BAL and blood CD4(+) and CD8(+) T cells by flow cytometry.

RESULTS

In BAL CD4(+) T cells, we noticed a significantly lower PPARα mRNA expression in sarcoidosis patients compared with HC. In non-LS patients, a significantly lower PPARα protein expression in BAL CD4(+) T cells was detected as compared with LS patients. In peripheral blood CD4(+) T cells, non-LS patients had a significantly lower expression of PPARα and PPARγ compared with LS patients.

CONCLUSION

The lower protein expression of PPARα and PPARγ could contribute to the persistent T-cell driven inflammation noted especially in non-resolving sarcoidosis, common in non-LS patients.