Blood gene expression of Toll-like receptors in SLE patients with lupus nephritis or neuropsychiatric systemic lupus erythematosus

Abstract

To determine differences in the blood innate gene expression signatures of systemic lupus erythematosus (SLE) patients across various organ manifestations and disease activity, with a focus on lupus nephritis (LN) and central nervous system (CNS) involvement. Toll-like receptor family (TLR 1–10) mRNA expression was investigated in peripheral blood mononuclear cells from patients with SLE (n = 74) and healthy controls (n = 34). We compared patients with histologically confirmed active LN or neuropsychiatric systemic lupus erythematosus (NPSLE) with patients without these symptoms. The expression of TLR mRNA was determined by RT‒qPCR using a high-throughput SmartChip Real-Time-qPCR system (WaferGen). Multivariate analysis and nonparametric statistics were used for data analysis to assess the associations between TLRs and disease activity and severity. TLR4 (0.044 vs. 0.081, p = 0.012) was upregulated and TLR10 (0.009 vs. 0.006, p = 0.0007) was downregulated in the whole cohort of SLE patients compared to healthy controls. A comparison of the active LN group with participants without kidney involvement revealed increased expression of TLR2 (0.078 vs. 0.03, p = 0.009), and TLR5 (0.035 vs. 0.017, p = 0.03). Moreover, a significant difference was observed in TLR9 expression between inactive LN and the control group (0.014 vs. 0.009, p = 0.01), together with borderline correlation in TLR2 expression (0.04 vs. 0.03, p = 0.06). Receiver operating characteristic (ROC) curve analysis revealed that TLR1 and TLR2 expression were the best potential diagnostic markers for active LN. The NPSLE group showed upregulation of TLR1 (0.088 vs. 0.048, p = 0.01), TLR4 (0.173 vs. 0.066, p = 0.0003) and TLR6 (0.087 vs. 0.036, 0.007). Our correlation analysis supported the close relationships among the expression of individual TLRs in the whole lupus cohort and its subgroups. Our study revealed differences in TLR expression between a lupus cohort and healthy controls. Additionally, our analysis provides insight into specific TLR expression in cases with severe organ manifestations, such as LN and NPSLE. The multiple mutual relationships of TLRs demonstrate the activation of innate immunity in SLE and suggest promising targets for future therapies or diagnostics.