High expression of pro-inflammatory cytokine genes IL-1β and IL-1R2 upon TLR4 activation in Takayasu arteritis

Toll-like receptors (TLR) 4 and its endogenous ligands are highly expressed in aorta. In the present study, we have explored the effect of TLR-4 activation by pro-inflammatory and angiogenic factors in PBMCs of patients with Takayasu Arteritis (TA). In the screening cohort, PBMCs of TA (n = 6) and healthy controls (n = 6) were stimulated with LPS and cultured. mRNA expression of 84 genes were quantitated by RT2 Profiler™ PCR Array kit in PBMCs. Validation set of additional PBMCs from TA (n = 7) and healthy controls [HC) (n = 7) were then stimulated with LPS to study expression of selected genes with delta Ct > 0.1 in the screening cohort. Significant gene expressions were correlated with Indian Takayasu arteritis activity scores (ITAS 2010). Increased expression of CCL2 was observed only in unstimulated PBMCs of patients with TA [median relative difference (RD) of 2.37] as compared to HC (RD 1.37, p < 0.03) in validation cohort, while stimulation with TLR4 ligand led to increased mRNA expression of IL-1β (RD 7.9, p < 0.028) and IL-1R2 (RD 0.08 p < 0.013) genes as compared to that of HC [RD of 5.32 for IL-1β and 0.01 for IL-1R2, respectively] in validation cohort. TLR4 activation also led to significantly higher expression of HPSE, TIMP1 and low expression of VEGFB, S1PR1, SERPINF1, ANGPLT4, ANGPT2, TIE1 and NOS3 genes in the screening cohort. But expression of VEGFB was not significant in validation cohort. The significant gene expressions, however, did not correlate with ITAS [ITAS2010 and ITAS-A (CRP)]. TLR4 activation leads to increased expression of IL-1β and IL-1R2 genes in PBMCs of patients with TA.