Background: Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are autoimmune diseases with some overlapping clinical manifestations. Recent studies have revealed that Toll-like receptors (TLRs) play essential roles in autoimmune diseases' pathogenesis. To investigate the expression of TLR genes in SLE and SSc that are specific to the character of these diseases' pathogenesis.Methods: We recruited patients with SLE (n = 15) and SSc (n = 9) from China Medical University Hospital hospital in Taiwan from 2016 to 2017. Included were healthy reference controls and SLE datasets from the NCBI database. RNA was extracted from peripheral blood cells of the patients for next-generation sequencing (NGS). Results in identified differentially expressed genes were compared to explore TLRs' association with SLE and SSc pathogenesis. Housekeeping genes, including ACTB, GAPDH, PGK1, PPIB, SDHA, and TBP, were used to normalize the expression levels of the TLR genes. Results: There were significant differences in raw gene expression for patients with SLE and SSc (p < 0.05). No significant difference between patients with SLE and control datasets with SLE (p >0.05). The expression levels of TLR1 (p = 0.018) and TLR3 (p = 0.031) were significantly upregulated in the patients with SSc compared with those with SLE, normalized by GAPDH. Compared with many housekeeping genes, ACTB, GAPDH, and TBP indicated a significant difference (p < 0.05) in the expression of TLR1and TLR3. Conclusions: TLR1 and TLR3 can serve as biomarkers to distinguish the gene expression between SLE and SSc, normalized with housekeeping genes such as ACTB, GADPH, and TBP.

Background: Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are autoimmune diseases with some overlapping clinical manifestations. SLE is characterized by systemic inflammation with vasculitis and multiple organ damage, whereas SSc manifests as low-grade inflammation with vasculopathy and tissue fibrosis. Recent studies have revealed that Toll-like receptors (TLRs) play essential roles in the pathogenesis of autoimmune diseases. This study investigated the expression of TLR genes in SLE and SSc to determine their roles in the pathogenesis of these diseases.Methods: Patients with SLE (n = 15) and SSc (n = 9) were recruited from a hospital in Taiwan from 2016 to 2017. RNA was extracted from peripheral blood cells of the patients for next-generation sequencing (NGS). Then, We identified differentially expressed genes and associated pathways to explore the association of TLRs with SLE and SSc pathogenesis. Several housekeeping genes, including ACTB, GAPDH, PGK1, PPIB, SDHA, and TBP, were used to normalize the expression levels of the TLR genes.Results: GAPDH, PGK1, PPIB and SDHA are significantly different (p < 0.05) in patients of SLE and SSc. The expression levels of TLR1 (p = 0.018) and TLR3 (p = 0.031) were significantly upregulated in the patients with SSc compared with those with SLE, normalized by GAPDH.Conclusions: TLR1 and TLR3 can serve as biomarkers to distinguish the gene expression between SLE and SSc, normalized with housekeeping genes such as ACTB, GADPH and TBP.