Presence of mRNA for interferon-gamma (IFN-gamma) in blood mononuclear cells is associated with an active stage I sarcoidosis

T-bet and interleukin-27: possible TH1 immunomodulators of sarcoidosis

Background

Sarcoidosis has often been termed an “immune paradox” as there is peripheral anergy to common recall antigens despite pronounced T_H1-dominant inflammation at disease sites, such as the lung, with up-regulation of interferon γ, IL-27 and transcription factors. Peripheral blood may reflect the anergic state, while exhaled breath condensate (EBC) analysis may offer insights into the lung disease.

Methods

A cross-sectional study was conducted to investigate the expression of T_H1 cytokines and transcription factors (IFNγ, IL-27 and T-bet) in the peripheral blood and/or EBC of sarcoidosis patients and healthy controls. Whole blood and EBC were collected from sarcoidosis patients and healthy controls. T_H1 cytokine expression levels were then measured in peripheral blood mononuclear cells (PBMCs) and/or plasma and EBC using quantitative real-time PCR, ELISA and via Western blotting.

Results

Compared to healthy controls, PBMC IL-27 mRNA was higher in patients (p = 0.0019). There were no significant differences in plasma IL-27 protein between patients and controls (p = 0.20). T-bet mRNA and protein were lower (p = 0.010 and p = 0.0043, respectively) in patients compared to controls. There were no significant differences in PBMC IFNγ mRNA and protein expression (p = 0.68 and p = 0.74, respectively) nor in EBC IL-27 levels.

Conclusions

Our data indicate that depressed T-bet mRNA and protein expression could contribute to the peripheral anergy in sarcoidosis and that IL-27 mRNA levels are elevated in the PBMC from those with sarcoidosis.

Electronic supplementary material

The online version of this article (doi:10.1007/s10787-015-0247-y) contains supplementary material, which is available to authorised users.

Combined association between IFN-gamma 3,3 homozygosity and DRB1*03 in Löfgren’s syndrome patients

In the present study, short tandem repeats (STR) polymorphism within the first intron of IFN-gamma gene in connection with HLA-DRB1*03 specificities was analysed in 43 sarcoidosis patients, 14 of which presented with Löfgren's syndrome (LS). Four out of 5 known IFN-gamma alleles with 12-15 CA repeats, respectively were detected in sarcoidosis patients. IFN-gamma 3,3 homozygosity was found to constitute a risk factor associating with LS manifestation (0.50 versus 0.19, OD = 4.18, P = 0.014). As expected, DRB1*03 prevailed in LS cases (9/14 versus 7/29, P = 0.014 LS versus non-LS cases and 9/14 versus 35/162, OD = 6.20, P = 0.001, LS patients versus controls). However, we also showed the presence of a combined association between DRB1*03 and IFN-gamma 3,3 in sarcoidosis (P = 0.017) and LS patients (P = 0.001).