Rheumatoid arthritis and cardiovascular disease

A novel murine model for chronic inflammatory alveolar bone loss

BACKGROUND AND OBJECTIVE

Chronic inflammatory bowel disease (IBD) demonstrates some similarities to the dysregulated chronic immunoinflammatory lesion of periodontitis. Trinitrobenzene sulphonic acid (TNBS) and dextran sodium sulphate (DSS) administered to rodents have been shown to elicit inflammatory responses that undermine the integrity of the gut epithelium in a similar manner to IBD in humans. The objective of this study was to evaluate the ability of these chemicals to elicit periodontal inflammation as a novel model for alveolar bone loss.

MATERIAL AND METHODS

Mice were treated by oral application of TNBS twice a week, or with DSS in the diet over a period of 18 weeks. Alveolar bone loss was assessed on the defleshed skull using morphometric measures for area of bone resorption.

RESULTS

The TNBS-treated animals tolerated oral administration with no clinical symptoms and gained weight at a similar rate to normal control animals. In contrast, DSS exerted a systemic response, including shortening of colonic tissue and liver enzyme changes. Both TNBS and DSS caused a localized action on periodontal tissues, with alveolar bone loss observed in both maxilla and mandibles, with progression in a time-dependent manner. Bone loss was detected as early as week 7, with more severe periodontitis increasing over the 18 weeks (p < 0.001). Young (7-month-old) and old (12-month-old) mice with severe combined immunodeficiency were treated with TNBS for a period of 7 weeks and did not develop significant bone loss.

CONCLUSION

These data show that oral administration of TNBS or DSS provokes alveolar bone loss in concert with the autochthonous oral microbiota.

Induction of CCR2-dependent macrophage accumulation by oxidized phospholipids in the air-pouch model of inflammation

OBJECTIVE

Macrophages are key players in the pathogenesis of rheumatoid synovitis as well as in atherosclerosis. To determine whether atherogenic oxidized phospholipids potentially contribute to synovial inflammation and subsequent monocyte/macrophage recruitment, we examined the effects of oxidized 1- palmitoyl-2-arachidonoyl-sn-3-glycero-phosphorylcholine (OxPAPC) on chemokine expression and leukocyte recruitment in a facsimile synovium in vivo using the murine air-pouch model.

METHODS

Air pouches were raised by 2 injections of sterile air, and inflammation was induced by injecting either lipopolysaccharide (LPS) or OxPAPC into the pouch lumen. Inflammation was assessed by analysis of inflammatory gene expression using reverse transcription-polymerase chain reaction or immunohistochemical analysis, and leukocytes were quantified in the lavage fluid and in the pouch wall after staining with Giemsa or after enzymatic digestion followed by fluorescence-activated cell sorter analysis.

RESULTS

Application of OxPAPC resulted in selective recruitment of monocyte/macrophages into the air-pouch wall, but not in the lumen. In contrast, LPS induced both monocyte and neutrophil accumulation in the pouch lumen as well as in the wall. LPS, but not OxPAPC, induced the expression of adhesion molecules E-selectin, P-selectin, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1. OxPAPC increased the expression of the CCR2 ligands monocyte chemotactic protein 1 (MCP-1), MCP-3, and MCP-5, as well as RANTES and growth-related oncogene alpha (GROalpha), while it down-regulated the expression of CCR2 on macrophages. Moreover, oxidized phospholipid-induced macrophage accumulation was abrogated in CCR2-/- mice.

CONCLUSION

These data demonstrate that oxidized phospholipids trigger a type of inflammatory response that leads to selective macrophage accumulation in vivo, a process relevant for the pathogenesis of chronic inflammatory rheumatic diseases.

Association of physical inactivity with increased cardiovascular risk in patients with rheumatoid arthritis

OBJECTIVE

Patients with rheumatoid arthritis (RA) are characterized by reduced physical activity and increased morbidity and mortality from cardiovascular disease (CVD). The aim of this study was to investigate associations between levels of physical activity and CVD risk profile in RA patients.

METHODS

Levels of physical activity were assessed in 65 RA patients (43 females). Using the International Physical Activity Questionnaire, patients were allocated into three groups: active, moderately active and inactive. Anthropometric characteristics, RA activity/severity, multiple classical and novel CVD risk factors and 10-year CVD event probability were assessed and compared among the three groups.

RESULTS

Significant differences were detected among groups in systolic blood pressure (P=0.006), cholesterol (P<0.001), low-density lipoprotein (P=0.01), homeostasis model assessment (P=0.001), type-I plasminogen activator inhibitor antigen (P<0.001), tissue-type plasminogen activator antigen (P=0.019), homocysteine (P=0.027), fibrinogen (P=0.001), apolipoprotein B (P=0.002) and von Willebrand Factor (P=0.001), with a consistent deterioration from the physically active to the physically inactive group. Multivariate analysis of variance revealed that levels of physical activity were significantly associated with the differences in all of the above variables (P<0.05) after adjustment for age, weight, sex, smoking status, as well as RA disease activity and severity.

CONCLUSION

This cross-sectional study suggests that physically inactive RA patients have significantly worse CVD risk profile compared with physically active patients. The possible beneficial impact of increased physical activity, including structured exercise, to the CVD risk of RA patients needs to be accurately assessed in prospective studies.

Impact of ezetimibe on atherosclerosis: is the jury still out?

Ezetimibe is a new lipid-lowering agent that inhibits intestinal absorption of dietary cholesterol. It substantially lowers low-density lipoprotein cholesterol levels when used alone or in combination with statins. However, its effect on cardiovascular mortality remains unknown. We reviewed peer-reviewed published literature on the effect of ezetimibe on different phases of atherosclerosis. MEDLINE, EMBASE, BIOSIS, and other Web of Knowledge databases were searched for relevant abstracts and articles published in the English language that compared ezetimibe and statins as modulators of atherosclerosis. On the basis of the available evidence, ezetimibe appears to reduce inflammation when used in combination with statins, but its effect on endothelial function is mixed and less clear. The effect of ezetimibe on coronary disease progression or prevention of cardiovascular events is currently unknown. Use of ezetimibe as a second- or third-line agent to achieve low-density lipoprotein cholesterol treatment goals seems appropriate on the basis of the available evidence.

High-density lipoprotein: does it have a dark side?

There are proven pleiotropic anti-atherogenic actions of high-density lipoprotein (HDL). However, in systemic inflammation, HDL can have pro-inflammatory properties that may contribute to accelerated atherosclerosis, likely mediated by a change in the structure of HDL to pro-inflammatory HDL (PiHDL). Validation of the technically challenging assay for PiHDL, and confirmation of an association of PiHDL in multiple populations with known risk for atherosclerosis will eventually provide a useful biomarker. Identification of PiHDL in patients with rheumatic disease may help identify patients at risk of accelerated atherosclerosis, and focus our therapeutic interventions.

Tumor necrosis factor (TNF) inhibitor therapy for rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disorder characterized by inflammation involving large and small joints. Systemic manifestations as well as involvement of paraoral tissues contribute to morbidity. Tumor necrosis factor (TNF) plays a central role in RA by amplifying inflammation in multiple pathways that lead to joint destruction. Tumor necrosis factor inhibitors were first licensed for clinical use in 1998; 3 have been approved for the treatment of RA: Iinfliximab, etanercept, and adalimumab. The purpose of this paper is to review the pathogenesis of RA, the state of the art of therapy, and the most current information on the safety and efficacy of TNF inhibitors for treatment of RA.