Atherosclerosis and complement: anaphylatoxin C5a as a new risk marker and therapeutic target

Use of capillary electrophoresis to select a DNA aptamer that recognizes swine anaphylatoxin C5a

Complement factor 5a is a potent proinflammatory mediator that contributes to the pathogenesis of numerous inflammatory diseases. Protein-based C5a inhibitors have proven to be clinically valuable. Aptamers, which are oligonucleic acid chains or polypeptides, can bind to target molecules and hence have the potential to be used for detection and blockade of targets. Here, we describe the discovery that the single-stranded DNA aptamer S1 can bind specifically to swine C5a, which can then be quickly selected for with capillary electrophoresis for high-throughput sequencing. Aptamer S1 bound specifically to swine C5a with a dissociation constant of 4 μM as measured by surface plasmon resonance (SPR). Moreover, aptamer S1 inhibited C5a-induced chemotaxis of neutrophils in vitro. Our study suggests that the S1 aptamer has great potential to be a key structure in the development of effective therapeutic agents against inflammatory diseases.

Effectiveness of C5a aptamers in a TNBS-induced colitis mouse model

The complement-activated product, complement component 5a (C5a), is a potent inflammatory peptide with a broad spectrum of functions. In vivo and in vitro studies have demonstrated that C5a serves an important role in inflammation; however, the role of C5a in the pathogenesis of inflammatory bowel disease (IBD) is not known. The purpose of the current study was to investigate the role of C5a in IBD using an experimental mouse model of colitis. Colitis was induced in mice using 2,4,6-trinitrobenzene sulfonic acid (TNBS), and C5a aptamers were subsequently administered via intraperitoneal injection. Clinical symptoms of the disease, histopathological analysis of the colon and the level of inflammatory components were examined. The symptoms of colitis, including changes in behavior, weight loss, colon damage and an increase in inflammatory cytokines, were attenuated following the treatment of mice with TNBS-induced colitis with C5a aptamers. The aptamer-treated mice exhibited a marked attenuation of colitis when compared with untreated mice, as demonstrated by the phenotypic observations, histological examinations and inflammatory cytokine levels. Colitis is characterized by an imbalance between pro-inflammatory and anti-inflammatory mediators. The results of the current study suggest that C5a may serve a critical role in inflammation in IBD.