Interleukin (IL)-10 is an anti-inflammatory cytokine that may play a protective role in atherosclerosis. The aim of this study was to assess the effect of IL-10 deficiency in the apolipoprotein E knockout mouse. Apolipoprotein E deficient (E-/-) and IL-10 deficient (-/-) mice were crossed to generate E-/ϫ IL-10-/double knockout mice. By 16 wk, cholesterol and triglycerides were similar in double and single knockouts but the lack of IL-10 led to increased low-density lipoprotein cholesterol whereas very-low-density lipoprotein was reduced. In parallel, T-helper 1 responses and lesion size were dramatically increased in double knockout compared with E-/controls. At 48 wk, matrix metalloproteinases and tissue factor activities were increased in lesions of double-knockout mice. Furthermore, markers of systemic coagulation were increased, and vascular thrombosis in response to i.v. thrombin occurred more frequently in E-/ϫ IL-10-/than in E-/mice. Our findings suggest that IL-10 deficiency plays a deleterious role in atherosclerosis. The early phase of lesion development was increased, and the proteolytic and procoagulant activity was elevated in advanced lesions. These data show that IL-10 may reduce atherogenesis and improve the stability of plaques.

This study demonstrates the involvement of the MMP/TIMP system in ECM remodelling of both AS and AR. These findings provide evidence of inflammatory injury more severe in AS than in AR and involvement of mesenchymal cell response.

No abstract

The exact aetiology and physiopathology of varicose disorders remain unclear. The aim of the present work was to study, in situ, the morphology and composition of cellular and matrix components in varicose veins compared with control veins and to identify factors that could contribute to varicose remodelling. A combined histological, immunohistochemical, and biochemical approach was used. Longitudinal sections of varicose (n=12) and control veins (n=9) were studied to assess the organization, structure, and phenotype of smooth muscle cells; the localization of microvascular endothelial cells; the distribution of connective tissue proteins; and the localization of cytokines. These cytokines were further quantified by ELISA. Considerable heterogeneity of the varicose vein wall was observed, with a succession of hypertrophic and atrophic segments, presenting severe disorganization of the medial layer and numerous areas of intimal thickening. In hypertrophic portions, medial smooth muscle cells showed marked alterations suggesting modulation from a contractile to a proliferative and synthetic phenotype; furthermore, the number of vasa vasorum was increased. In contrast, in atrophic portions, both cellular and matrix components were decreased. TGFbeta1 (p< or =0.005) and bFGF (p< or =0.001) were increased and VEGF was not significantly modified in varicose veins when the results were expressed per mg of DNA. These results show that phenotypic modulation of smooth muscle cells, altered extracellular matrix metabolism, and angiogenesis are the main mechanisms contributing to the morphological and functional modifications of varicose remodelling. The increased expression of bFGF and TGFbeta1 by varicose vein cells may play a pivotal role in the hypertrophy of the venous wall, but the exact mechanism leading to aneurysmal dilatations remains to be elucidated.

Elastin is the macromolecular polymer of tropoelastin molecules responsible for the elastic properties of tissues. The understanding of its specific elasticity is uncertain because its structure is still unknown. Here, we report the first experimental quantitative determination of bovine elastin secondary structures as well as those of its corresponding soluble -elastin. Using circular dichroism and Fourier transform infrared and near infrared Fourier transform Raman spectroscopic data, we estimated the secondary structure contents of elastin to be ϳ10% ␣-helices, ϳ45% ␤-sheets, and ϳ45% undefined conformations. These values were very close to those we had previously determined for the free monomeric tropoelastin molecule, suggesting thus that elastin would be constituted of a closely packed assembly of globular ␤ structural class tropoelastin molecules crosslinked to form the elastic network (liquid drop model of elastin architecture). The presence of a strong hydration shell is demonstrated for elastin, and its possible contribution to elasticity is discussed.

No abstract

The therapeutic potential of low-molecular-weight (LMW) fucoidan, a sulfated polysaccharide extracted from brown seaweed devoid of direct antithrombin effect, was investigated in vitro and in a model of critical hindlimb ischemia in rat. In vitro results showed that LMW fucoidan enhanced fibroblast growth factor (FGF)-2-induced [ 3 H]thymidine incorporation in cultured rat smooth muscle cells. Intravenous injection in rats of LMW fucoidan significantly increased the stromal-derived factor (SDF)-1 level from 1.2 Ϯ 0.1 to 6.5 Ϯ 0.35 ng/ml in plasma. The therapeutic effect of LMW fucoidan (5 mg/kg/day), FGF-2 (1 g/kg/day), and LMW fucoidan combined with FGF-2 was assessed 14 days after induction of ischemia by 1) clinical evaluation of claudication, 2) tissue blood flow analysis, 3) histoenzymology of muscle metabolic activity, and 4) quantification of capillary density. Both LMW fucoidan and FGF-2 similarly improved residual muscle blood flow (62.5 Ϯ 6.5 and 64.5 Ϯ 4.5%, respectively) compared with the control group (42 Ϯ 3.5%, p Ͻ 0.0001). The combination of FGF-2 and LMW fucoidan showed further significant improvement in tissue blood flow (90.5 Ϯ 3%, p Ͻ 0.0001). These results were confirmed by phosphorylase activity, showing muscle regeneration in rats treated with the combination of FGF-2 and LMW fucoidan. Capillary density count increased from 9.6 Ϯ 0.7 capillaries/muscle section in untreated ischemic controls to 14.3 Ϯ 0.9 with LMW fucoidan, 14.5 Ϯ 0.9 with FGF-2, and 19

Elastic fiber formation involves the secretion of tropoelastin which is converted to insoluble elastin by cross-linking, initiated by the oxidative deamination of lysine residues by lysyl oxidase. Five lysyl oxidase genes have been discovered. This study deals with the expression of two isoforms, LOX and LOX-like (LOXL), in human foreskin and in a human skin-equivalent (SE) model that allows the formation of elastic fibers. In this model, keratinocytes are added to a dermal equivalent made of fibroblasts grown on a chitosan-cross-linked collagen-GAG matrix. LOX and LOXL were detected by immunohistochemistry in the dermis and the epidermis of both normal skin and in a SE. This expression was confirmed by in situ hybridization on the SE. LOX and LOXL expression patterns were confirmed in human skin. The ultrastructural localization of LOXL was indicative of its association with elastin-positive materials within the SE and human skin, though interaction with collagen could not be discarded. LOX was found on collagen fibers and could be associated with elastin-positive materials in the SE and human skin. LOXL and LOX were detected in keratinocytes where LOX was mainly expressed by differentiating keratinocytes, in contrast to LOXL that can be found in both proliferating and differentiating fibroblasts. These data favor a role for LOXL in elastic fiber formation, together with LOX, and within the epidermis where both enzymes should play a role in post-translational modification of yet unknown substrates.