Vascular damage and lack of angiogenesis in systemic sclerosis skin.

The aim of this study was to analyse microvascular damage and compensatory angiogenesis in skin from patients with systemic sclerosis (SSc) compared with systemic lupus erythematosus (SLE), Raynaud's phenomenon (RP) and healthy controls. Immunohistochemistry was used for skin biopsies (9 SSc, 10 SLE, 9 RP and 12 healthy controls) using von Willebrand factor and beta3 integrin subunit specific antibodies, TechMate immunostaining robot and biotin-streptavidin protocol. In the early stages of SSc, vWF was found in the perivascular space and interstitial matrix in papillary but not in the reticular dermis, in particular around small oedematous blood vessels infiltrated by mononuclear cells. The extravascular release of vWF in SSc specimens was associated with weak or even a total lack of immunoreactivity within the associated endothelial cells. Late stages of SSc were characterised by loss of the dermal papillae, subepidermal fibrosis, hypovascularity and strong endothelial vWF expression without extravascular leakage. In all SSc patients studied only a few vascular profiles were weakly immunostained for beta3 integrin subunit. This work demonstrates that vWF is not only released into the systemic circulation, but is also leaked to the perivascular space/matrix. This local release and deposition of vWF is probably a sensitive and early marker of microvascular involvement in SSc pathogenesis. Local vWF release may play a role in platelet adhesion, aggregation, thrombogenesis and dermal connective tissue remodelling. In spite of some attempts towards compensatory angiogenesis in SSc, as evidenced by beta3 integrin subunit expression, it was evident that the angiogenic response was not able to prevent the development of hypovascularity during the advanced stages of the disease.

Dual effects of caspase-1, interleukin-1 beta, tumour necrosis factor-alpha and nerve growth factor receptor in inflammatory myopathies.

OBJECTIVE: To analyse the expression of factors potentially involved in skeletal muscle degeneration and regeneration in dermatomyositis (DM), systemic sclerosis (SSc), polymyositis (PM), systemic lupus erythematosus (SLE) and non-inflammatory myopathies. METHODS: Immunohistochemical staining of skeletal muscle biopsies (10 DM, 10 SSc, 10 PM, 10 SLE, 10 non-inflammatory myopathies) for tumour necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), activated caspase-1, pan-macrophage marker CD68, inducible nitric oxide synthase (NOS2) and nerve growth factor receptor (NGFR). TechMate staining robot and biotin-streptavidin protocol were used. RESULTS: Expression of TNF-alpha, IL-1 beta, caspase-1 and NOS2 was found in the cytoplasm and sarcolemma of dystrophic skeletal muscle fibres. TNF-alpha and IL-1 beta immunoreactive profiles were faint and few and close to satellite nuclei-containing regenerating muscle fibres both in inflammatory and non-inflammatory myopathies. NGFR expression was found in comparable areas. In non-inflammatory inherited myopathies more nuclei were caspase-1 immunoreactive whereas caspase-1 expression was rarely seen in inflammatory myopathies, implying regeneration of the affected muscle fibres. CONCLUSION: Prominent expression of the proinflammatory factors TNF-alpha, IL-1 beta and NOS2 and caspase-1 is associated with muscle fibre damage, albeit when expressed to a low degree these factors may, like NGFR, contribute to muscle regeneration and healing.

Increased but imbalanced expression of VEGF and its receptors has no positive effect on angiogenesis in systemic sclerosis skin.

OBJECTIVE: To investigate the expression of vascular endothelial growth factor (VEGF) and its vascular and lymphatic receptors in skin in systemic sclerosis (SSc) compared to systemic lupus erythematosus (SLE), Raynaud's phenomenon (RP) and normal healthy control skin. METHODS: Staining was performed using rabbit anti-human antibodies in DAKO TechMate Horizon staining robot programmed for the biotin-streptavidin protocol. RESULTS: VEGF was sporadically and weakly expressed in normal skin, but in spite of vascular damage in diseased skin, VEGF expression was only slightly upregulated. In contrast, its vascular receptors VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1), were clearly upregulated. Finally, the lymphatic VEGFR-3 (Flt-4) receptor was also upregulated in diseased skin and ectopically expressed also in blood vessels. Negative staining and positive sample controls confirmed the specificity of the staining. CONCLUSION: The imbalanced expression of VEGF and its vascular receptors suggest that the compensatory efforts to angiogenesis fail in SSc, in part due to insufficient local production of VEGF, which was low compared to VEGFR expression. This is compatible with the recent observations on the lack of alpha V beta 3+ newly formed blood vessels in SSc skin. Since microvascular angiogenic stimuli normally induce first VEGF and then VEGFR, these findings also suggest that the angiogenic cascade is turned on, but there is a defect in the finalization of its effects. Normalization of angiogenic cascade in SSc could provide a future therapeutic target.