mRNA expression analysis confirms CD44 splicing impairment in systemic lupus erythematosus patients

Abstract

Background Systemic Lupus Erythematosus (SLE) is a complex chronic autoimmune disease characterized by several immunological alterations. T cells have a peculiar role in SLE pathogenesis, moving from the bloodstream to the peripheral tissues, causing organ damage. This process is possible for their increased adherence and migration capacity mediated by adhesion molecules, such as CD44. Ten different variant isoforms of this molecule have been described, and two of them, CD44v3 and CD44v6 have been found to be increased on SLE T cells compared to healthy controls, being proposed as biomarkers of disease and disease activity. The process of alternative splicing of CD44 transcripts is not fully understood. We investigated the mRNA expression of CD44v3 and CD44v6 and also analyzed possible CD44 splicing regulators (ESRP1 molecule and rs9666607 CD44 polymorphism) in a cohort of SLE patients compared to healthy controls. Methods This study involved 18 SLE patients and 18 healthy controls. Total RNA and DNA were extracted by peripheral blood mononuclear cells. The expression study was conducted by quantitative RT-polymerase chain reaction, using SYBR Green protocol. Genotyping of rs9666607 SNP was performed by direct sequencing. Results CD44v6 mRNA expression was higher in SLE patients compared to healthy controls (p = 0.028). CD44v3/v6 mRNA ratio in healthy controls was strongly unbalanced towards isoform v3 compared to SLE patients (p = 0.002) and decreased progressively from healthy controls to the SLE patients in remission and those with active disease (p = 0.015). The expression levels of CD44v3 and CD44v6 mRNA correlated with the disease duration (p = 0.038, Pearson r = 0.493 and p = 0.038, Pearson r = 0.495, respectively). Splicing regulator ESRP1 expression positively correlated with CD44v6 expression in healthy controls (p = 0.02, Pearson r = 0.532) but not in SLE patients. The variant A allele of rs9666607 of CD44 was associated with higher level of global CD44 mRNA (p = 0.04) but not with the variant isoforms. Conclusions In SLE patients, the increase in CD44v6 protein correlates with a higher transcript level of this isoform, confirming an impairment of CD44 splicing in the disease, whose regulatory mechanisms require further investigation.

Progress in the application of body fluid and tissue level mRNAs-non-coding RNAs for the early diagnosis and prognostic evaluation of systemic lupus erythematosus

“…Adhesion and migration mediated by adhesion molecules are associated with the pathogenesis of SLE, and the high expression of CD44v6 mRNA in PBMCs is correlated with disease duration ( 50 ). The mRNA expression of METTL14, ALKBH5, and YTHDF2 is increased in PBMCs of SLE patients.…”

Prediction of CD44 Structure by Deep Learning-Based Protein Modeling

“…CD44v6 has been widely confirmed as a marker of cancer with metastatic potential, and its inhibition is proving to be a therapeutic strategy [9][10][11][12]. Other isoforms have been proposed as candidate biomarkers of inflammatory processes such as allergic asthma [13], systemic lupus erythematosus (SLE) [14,15], and multiple sclerosis (MS) [16][17][18].…”

A TLR/CD44 axis regulates T cell trafficking in experimental and human multiple sclerosis

“…Moreover, it has been previously described a specific role of CD44 isoforms in the pathogenesis of immunomodulated diseases (Di Sante et al, 2013), whereas involvement of CD44v5 was shown in the pathogenesis of asthma (Yang et al, 2012). In addition, CD44 v3/v6 was proposed as biomarker of disease activity in systemic lupus erythematosus (SLE) (Latini et al, 2021;Novelli et al, 2019). Decrease of CD44 expression leads to a reduction of adhesive interactions with lymph node matrix, thereby facilitating the exit of T cells from lymph nodes (Brennan et al, 1997;McDonald and Kubes, 2015).…”