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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12950-015-0071-6) contains supplementary material, which is available to authorized users.