Reduction of cPLA_2α overexpression: An efficient anti‐inflammatory therapy for collagen‐induced arthritis

Abstract

Cytosolic phospholipase A 2a (cPLA 2 ) plays an important role in the development of several inflammatory diseases. The aim of the present study is to determine whether inhibition of cPLA 2 expression, using specific antisense oligonucleotides against cPLA 2 (antisense), is efficient in reducing inflammation after its development. Two mouse models of inflammation were included in the study: thioglicolate peritonitis and collagen-induced arthritis (CIA). The antisense was found to be specific and efficient in inhibiting cPLA 2 expression and NADPH oxidase activity ex vivo in peritoneal phagocytes. Immunoblotting and immunohistochemistry analysis showed a significant elevation in cPLA 2 expression in the inflamed joints of collagen-induced arthritis mice localized in cell infiltrate, chondrocytes and the surrounding skin and skeletal muscle. Similarly, the cPLA 2 metabolite, leukotriene B 4 , accumulated in the peritoneal cavity of mice with peritonitis. Inhibition of elevated cPLA 2 expression after development of inflammation by intravenous administration of antisense resulted in a dramatic reduction in inflammation and a significant reduction in neutrophils recruitment to the site of inflammation in both mouse models of inflammation. Our results demonstrate the critical role of cPLA 2 for the duration of inflammation and suggest that inhibition of cPLA 2 expression by antisense oligonucleotides may serve as an efficient treatment of inflammatory diseases. IntroductionRheumatoid arthritis is an autoimmune inflammatory disease that affects 1% of the population. It is characterized by polyarticular joint inflammation with leukocytic recruitment into synovial fluid and tissue, which appears as a symmetric polyarticular arthritis and which is associated with joint deformities of the hands and feet [1]. Despite extensive efforts, its etiology and pathogenesis remain poorly understood, and effective therapies with limited side effects are still lacking. Collagen-induced arthritis (CIA) in mice is an experimental model that reproduces many of the pathogenic mechanisms of human rheumatoid arthritis, such as increased cellular infiltration, synovial hyperplasia, pannus formation and erosion of cartilage and bone in the distal joints [2]. In humans and in murine arthritis models, chemokines and other chemoattractants [11] knock-out mice suggest that both prostaglandins and LT play an important role in the onset of CIA. Furthermore, dual inhibitors of 5-lipoxygenase and COX were more effective than selective COX inhibitors in preventing arthritis [12]. We have previously provided evidence that cPLA 2 , in addition to its known role in participating in eicosanoid production [13], regulates the phagocyte NADPH oxidase-releasing superoxides [14][15][16]. Moreover, consistent with many other studies, we have demonstrated in vivo and in vitro that during inflammation, the level and activity of both cPLA 2 and NADPH oxidase enzymes are elevated in neutrophils and monocytes [17,18]. Inhibition of overexpressed cPLA 2 protein du...

FAN Stimulates TNFα-Induced Gene Expression, Leukocyte Recruitment, and Humoral Response

“…injection of thioglycollate, a widely used proinflammatory compound. Under our experimental conditions, neutrophil recruitment elicited by thioglycollate was maximal at 24 h (data not shown), in agreement with previous reports (28,29). Thioglycollate triggered a time-dependent neutrophil and macrophage recruitment in both groups, albeit to a lesser extent in FAN Ϫ/Ϫ mice, at 24 h (Figs.…”

Metabolic products of soluble epoxide hydrolase are essential for monocyte chemotaxis to MCP-1 in vitro and in vivo

“…Alternatively, because sEH inhibition is not complete, addition of EETs may merely lead to elevations in DHETs from the remaining sEH activity. cPLA 2 plays a major role in the development of several infl ammatory diseases ( 32 ). AA is believed to be the critical mediator for cPLA 2 -regulated infl ammation.…”

Cytosolic phospholipase A2 alpha inhibitor, pyrroxyphene, displays anti-arthritic and anti-bone destructive action in a murine arthritis model

“…This treatment reduced inflammation in collagen-induced arthritis in mice [25]. However, the inhibitory effects of administration of cPLA2 alpha inhibitors after the onset of inflammation on arthritic symptoms remain to be elucidated.…”