Drug screening and identification of key candidate genes and pathways of rheumatoid arthritis.

Rheumatoid arthritis (RA), which normally manifests as a multi­joint inflammatory reaction, is a common immunological disease in clinical practice. However, the pathogenesis of RA has not yet been fully elucidated. Rituximab (RTX) is an effective drug in the treatment of RA, however its therapeutic efficacy and mechanism of action require further investigation. Thus, the present study aimed to screen the candidate key regulatory genes and explain the potential mechanisms of RA. Gene chips of RA and normal joint tissues were analyzed and, gene chips of RTX before and after treatment were investigated. In the present study, strong evidence supporting the pathogenesis of RA and mechanism of action of RTX were also revealed. Differentially expressed genes (DEGs) were analyzed using the limma package of RStudio software. A total of 1,150 DEGs were detected in RA compared with normal joint tissues. The upregulated genes were enriched in 'interleukin­12 production', 'I­κB kinase/NF­κB signaling', 'regulation of cytokine production involved in immune response' and 'cytokine metabolic process'. Functional enrichment analysis showed that RTX was primarily involved in the inhibition of 'adaptive immune response', 'B cell activation involved in immune response' and 'immune effector process'. Subsequently, leukocyte immunoglobulin­like receptor subfamily B member 1 (LILRB1), a hub gene with high connectivity degree, was selected, and traditional Chinese medicine libraries were molecularly screened according to the structure of the LILRB1 protein. The results indicated that kaempferol 3­O­ß­D­glucosyl­(1→2)­ß­D­glucoside exhibited the highest docking score. In the present study, the DEGs and their biological functions in RA and the pharmacological mechanism of RTX action were determined. Taken together, the results suggested that LILRB1 may be used as a molecular target for RA treatment, and kaempferol 3­O­ß­D­glucosyl­(1→2)­ß­D­glucoside may inhibit the pathological process of RA.

LILRB1 Intron 1 Has a Polymorphic Regulatory Region That Enhances Transcription in NK Cells and Recruits YY1.

LILRB1 is a highly polymorphic receptor expressed by subsets of innate and adaptive immune cells associated with viral and autoimmune diseases and targeted by pathogens for immune evasion. LILRB1 expression on human NK cells is variegated, and the frequency of LILRB1+ cells differs among people. However, little is known about the processes and factors mediating LILRB1 transcription in NK cells. LILRB1 gene expression in lymphoid and myeloid cells arises from two distinct promoters that are separated by the first exon and intron. In this study, we identified a polymorphic 3-kb region within LILRB1 intron 1 that is epigenetically marked as an active enhancer in human lymphoid cells and not monocytes. This region possesses multiple YY1 sites, and complexes of the promoter/enhancer combination were isolated using anti-YY1 in chromatin immunoprecipitation-loop. CRISPR-mediated deletion of the 3-kb region lowers LILRB1 expression in human NKL cells. Together, these results indicate the enhancer in intron 1 binds YY1 and suggest YY1 provides a scaffold function enabling enhancer function in regulating LILRB1 gene transcription in human NK cells.