Soluble CD14 (sCD14) is involved in innate immune responses and has been implicated to play a pathogenic role in inflammatory diseases including rheumatoid arthritis (RA). No studies have identified the specific factors that influence sCD14 expression in RA. We used cross-sectional data to evaluate the relationship of sCD14 concentrations in RA with measures of disease activity and severity. We hypothesized that sCD14 concentrations would be elevated in subjects with greater RA disease severity and markers of disease activity, compared to subjects with lower disease activity. We also examined whether well-defined polymorphisms in CD14 are associated with sCD14 expression in RA.
Soluble CD14 concentrations were measured using banked serum from patients with RA (n = 1270) and controls (n = 186). Associations of patient factors including demographics, measures of RA disease activity/severity, and select CD14 single-nucleotide polymorphisms (SNP) with sCD14 concentration were examined in patients with RA using ordinal logistic regression.
Circulating concentrations of sCD14 were higher in patients with RA compared to controls (p < 0.0001). Factors significantly and independently associated with higher sCD14 levels in patients with RA included older age, being white (vs African American), lower body mass index, elevated high sensitivity C-reactive protein, and higher levels of disease activity based on the Disease Activity Score (DAS28). There were no significant associations of CD14 tagging SNP with sCD14 level in either univariate or multivariable analyses.
Circulating levels of sCD14 are increased in RA and are highest in patients with increased levels of RA disease activity. In the context of RA, sCD14 concentrations also appear to be strongly influenced by specific patient factors including older age and race but not by genetic variation in CD14.
"Only 2 studies had investigated the role of this polymorphism in RA and both concluded that the CD14 C/T -159 SNP do not constitute a predisposition factor to RA and do not influence its severity [29,30]. Inversely, levels of sCD14 were correlated to RA susceptibility, disease activity and occurrence of radiological damage [29,30] confirming that CD14 is deeply involved in RA pathogenesis. The fact that the investigation of CD14 C/T -159 SNP failed to confirm its impact might be due to, first genetic and epigenetic factors that could influence the gene transcription, second to a weak role that could be missed in case control studies. "
[Show abstract][Hide abstract] ABSTRACT: Background:
Toll-like receptor 4 (TLR4) and its co-receptor CD14 play a major role in innate immunity by recognizing PAMPs and signal the activation of adaptive responses. These receptors can recognize endogenous ligands mainly auto-antigens. In addition, TLR4 (Asp299Gly) and CD14 (C/T -159) polymorphisms (SNPs) may modify qualitatively and/or quantitatively their expression. Therefore, they could be implied in autoimmune diseases and can influence both susceptibility and severity of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).
Patients and methods:
TLR4 (Asp299Gly) and CD14 (C/T -159) SNPs were genotyped using polymerase chain reaction (PCR)-RFLP in 127 SLE patients, 100 RA patients, and 114 healthy controls matched in age and gender.
CD14*T allele was significantly more frequent in SLE patients (0.456) comparatively to controls (0.355), p = 0.02 OR (95% CI) = 1.53 [1.04-2.24]. In RA patients, the higher frequency of CD14*T allele (0.405) failed to reach significance, p = 0.28. Investigation of the TLR4 (Asp299Gly) SNP showed no significant association neither with SLE nor with RA.Analysis of these SNPs according to clinical and biological features showed a significant higher frequency of arthritis in SLE patients carrying CD14*T/T genotype (92%) comparatively to those with C/C and C/T genotypes (72.5%), p = 0.04. Moreover, SLE patients carrying CD14*T/T/TLR4*A/A haplotype had significantly more arthritis (91.3%) than the rest of SLE group (73%), p = 0,044 and confirmed by multivariable analysis after adjustment according to age and gender, p = 0.01.
The CD14 (-159)*T allele seems to be associated with susceptibility to SLE and arthritis occurrence.
[Show abstract][Hide abstract] ABSTRACT: The substitution of an active-site aspartic acid residue by asparagine in the lysosomal protease cathepsin D (CTSD) results in a loss of enzyme activity and severe cerebrocortical atrophy in a novel form of neuronal ceroid lipofuscinosis in sheep [Tyynelä, Sohar, Sleat, Gin, Donnelly, Baumann, Haltia and Lobel (2000) EMBO J. 19, 2786-2792]. In the present study we have introduced the corresponding mutation by replacing aspartic acid residue 293 with asparagine (D293N) into the mouse CTSD cDNA to analyse its effect on synthesis, transport and stability in transfected HEK-293 cells. The complete inactivation of mutant D293N mouse CTSD was confirmed by a newly developed fluorimetric quantification system. Moreover, in the heterologous overexpression systems used, mutant D293N mouse CTSD was apparently unstable and proteolytically modified during early steps of the secretory pathway, resulting in a loss of mass by about 1 kDa. In the affected sheep, the endogenous mutant enzyme was stable but also showed the shift in its molecular mass. In HEK-293 cells, the transport of the mutant D293N mouse CTSD to the lysosome was delayed and associated with a low secretion rate compared with wild-type CTSD. These data suggest that the mutation may result in a conformational change which affects stability, processing and transport of the enzyme.
[Show abstract][Hide abstract] ABSTRACT: Objective:
CD14 is a glycosylphosphotidylinositol-anchored membrane glycoprotein expressed on neutrophils and monocytes/macrophages that also circulates as a soluble form (sCD14). Despite the well-recognized role of CD14 in inflammation, relatively little is known about the genetic determinants of sCD14 or the relationship of sCD14 to vascular- and aging-related phenotypes.
Methods and results:
We measured baseline levels of sCD14 in >5000 European-American and black adults aged 65 years and older from the Cardiovascular Health Study, who were well characterized at baseline for atherosclerotic risk factors and subclinical cardiovascular disease, and who have been followed for clinical cardiovascular disease and mortality outcomes up to 20 years. At baseline, sCD14 generally showed strong positive correlations with traditional cardio-metabolic risk factors and with subclinical measures of vascular disease such as carotid wall thickness and ankle-brachial index (independently of traditional cardiovascular disease risk factors), and was also inversely correlated with body mass index. In genomewide association analyses of sCD14, we (1) confirmed the importance of the CD14 locus on chromosome 5q21 in European-American; (2) identified a novel African ancestry-specific allele of CD14 associated with lower sCD14 in blacks; and (3) identified a putative novel association in European-American of a nonsynonymous variant of PIGC, which encodes an enzyme required for the first step in glycosylphosphotidylinositol anchor biosynthesis. Finally, we show that, like other acute phase inflammatory biomarkers, sCD14 predicts incident cardiovascular disease, and strongly and independently predicts all-cause mortality in older adults.
CD14 independently predicts risk mortality in older adults.
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