Vascular Endothelial Growth Factor Expression In Fibroblasts Research Articles

Hydrolyzed Collagen Induces an Anti-Inflammatory Response That Induces Proliferation of Skin Fibroblast and Keratinocytes.

Collagen-based products are found in different pharmaceuticals, medicine, food, and cosmetics products for a wide variety of applications. However, its use to prevent or improve the health of skin is growing dizzyingly. Therefore, this study investigated whether collagen peptides could induce fibroblast and keratinocyte proliferation and activation beyond reducing an inflammatory response induced by lipopolysaccharide (LPS). Human skin fibroblasts (CCD-1072Sk) and human keratinocytes (hKT-nh-skp-KT0026) were seeded at a concentration of 5 × 104 cells/mL. LPS (10 ng/mL) and three doses of collagen peptides (2.5 mg/mL, 5 mg/mL, 10 mg/mL) were used. The readout parameters were cell proliferation; expression of inducible nitric oxide synthase (iNOS); expression of pro-collagen-1α by fibroblasts; and secretion of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor α (TNF-α), transforming growth factor β (TGF-β), and vascular endothelial growth factor (VEGF) by both cell types. The results demonstrated that all doses of collagen supplementation induced increased proliferation of both human fibroblasts (p < 0.01) and human keratinocytes (p < 0.001), while only the dose of 10 mg/mL induced an increased expression of pro-collagen-1α by fibroblasts. Similarly, only the dose of 10 mg/mL reduced LPS-induced iNOS expression in fibroblasts (p < 0.05) and keratinocytes (p < 0.01). In addition, collagen supplementation reduced the LPS-induced IL-1β (p < 0.05), IL-6 (p < 0.001), IL-8 (p < 0.01), and TNF-α (p < 0.05), and increased the TGF-β and VEGF expression in fibroblasts. Furthermore, collagen supplementation reduced the LPS-induced IL-1β (p < 0.01), IL-6 (p < 0.01), IL-8 (p < 0.01), and TNF-α (p < 0.001), and increased the TGF-β (p < 0.05) and VEGF (p < 0.05) expression in keratinocytes. In conclusion, collagen peptides were found to induce fibroblast and keratinocyte proliferation and pro-collagen-1α expression, involving increased expression of TGF-β and VEGF, as well as the suppression of an inflammatory response induced by LPS.

The extra domain A of fibronectin facilitates osteoclastogenesis in radicular cysts through vascular endothelial growth factor.

To analyse the effects of the alternatively spliced fibronectin (FN) gene and its isoforms on osteoclastogenesis in radicular cysts. Specimens of radicular cysts were collected surgically from 22 patients whose radiolucent periapical areas were measured on digital panoramic radiographs before surgery. The associations between the radiolucent areas and FN isoforms, vascular endothelial growth factor (VEGF) expression or micro-vessel density, as well as the relationships amongst them, were analysed by immunohistochemical staining using the antibodies IST-9, BC-1, P1F11, VEGF and CD34. Fibroblasts isolated from those specimens were used to induce Trap+MNCs, and the effects of induction were assessed by blocking FN containing extra domain A (EDA+FN), COX-2 or VEGF in vitro. The effects of EDA exon knockout using CRISPR/Cas system were also assessed. Quantitative PCR was used to analyse relative expression of FN isoforms and osteoclastogenic genes. Data were analysed using linear regression, Spearman's rank correlation analysis, chi-square test and Student's t-test; P<0.05 was considered significant. Micro-vessel density and EDA+FN staining were positively associated with the size of radiolucent periapical areas (mm2 ; P<0.05), consistent with a positive association between Trap+MNCs and VEGF expression in fibroblasts (P<0.05). Blocking the interaction between EDA+FN and fibroblasts inhibited Trap+MNC formation. In addition, EDA exon knockout decreased VEGF expression and inhibited Trap+MNC formation to the extent of blocking VEGF by bevacizumab, but osteoclastogenic induction was restored by recombinant VEGF. Using retrospective clinicopathological data, VEGF staining was shown to be positively associated with EDA+FN staining, micro-vessel density and the size of radiolucent areas (P<0.05). In fibrous capsules of radicular cysts, the alternatively spliced isoform EDA+FN generated by fibroblasts stimulated VEGF expression via an autocrine effect and then facilitated osteoclastogenesis. Both blockage of VEGF and EDA exon knockout could be used to inhibit bone destruction.

VEGF expression is augmented by hypoxia-induced PGIS in human fibroblasts

Prostacyclin synthase (PGIS or PTGIS) is an enzyme that catalyses the conversion of prostaglandin H2 (PGH2) to prostaglandin I2 (PGI2). PGI2 promotes cancer growth by activating peroxisome proliferator-activated receptor δ (PPARδ), and increases the expression levels of the pro-angiogenic factor vascular endothelial growth factor (VEGF). We found that the expression of the PGIS gene was enhanced in WI-38, TIG-3-20 and HEL human lung fibroblast cells and two cancer cell lines (NB-1 and G361) under hypoxic conditions. The main localization of PGIS changed from the cytoplasm to the nucleus by hypoxia in WI-38 cells. The induced PGIS had an enzymatic activity since the intracellular level of 6-keto-prostaglandin, a useful marker of PGI2 biosynthesis in vivo, was increased with the increasing levels of PGIS. Expression of VEGF was increased in parallel with PGIS induction under hypoxic conditions. PGIS knockdown resulted in the decreased expression of VEGF mRNA. Since VEGF is a known PPARδ target gene, we examined the effects of siRNAs targeting PPARδ on the expression of VEGF under hypoxic conditions. Knockdown of PPARδ suppressed the expression of VEGF under hypoxic conditions in WI-38 cells. These findings suggest that PGIS is induced by hypoxia and regulates the expression of VEGF in fibroblasts. Fibroblasts in the hypoxic area of tumors may have an important role in tumor growth and angiogenesis.

Effects of Topical Copper Tripeptide Complex on Wound Healing in an Irradiated Rat Model

To evaluate clinical and immunohistopathological effects of topical glycyl-histidyl-lysine-copper (GHK-Cu) on in vivo irradiated rat wounds. Animal model. Academic institution. After dorsal irradiation and a 28-day recovery period, 2 × 8 cm cranially based dorsal flaps were created in Sprague-Dawley rats. Twice daily GHK-Cu gel (test) or aquaphilic ointment (control) was applied for 10 days. Animals were euthanized, digital images of flaps were taken, and harvested tissues were immunohistochemically stained for a vascular endothelium marker, caveolin-1, and vascular endothelial growth factor (VEGF). Digital image analysis was used for outcome measures. Unpaired t-tests were used for statistical analyses; significance of P < .01 accounted for multiple comparisons. By digital analysis of clinical images, 13 test and 10 control animals showed mean ischemic areas of 5.0 cm(2) (SD = 0.9) for tests and 3.8 cm(2) (SD = 1.1; P = .011) for controls. Whole slide digitized images allowed quantification of caveolin-1-stained blood vessels and VEGF expression in fibroblasts at the interface of healing flaps. Caveolin-1 analyses showed a mean of 209.0 vessels (SD = 111.1) and a mean vessel luminal area of 525.7 um(2) (SD = 191.0) in tests and 207.4 vessels (SD = 109.4; P = .973) and 422.8 um(2) (SD = 109.7; P = .118) in controls. VEGF quantified as the percentage of pixels exceeding a colorimetric threshold, with higher fractions of positive pixels indicating more intense staining, showed a mean intensity score of 0.34 (SD = 0.19) in tests and 0.54 (SD = 0.41; P = .169) in controls. Irradiated dorsal rat flaps treated with topical GHK-Cu gel demonstrated no difference in flap ischemia, blood vessel number or area, or VEGF expression compared to controls.

Prostaglandin E2 stimulates VEGF expression in primary rat gastric fibroblasts through EP4 receptors

Vascular endothelial growth factor (VEGF), a fundamental regulator of angiogenesis, plays an important role in gastric ulcer healing. In addition, prostaglandin E2 (PGE2), derived from cyclooxygenase-2, stimulates VEGF release in gastric fibroblasts. In the present study, we examined which EP receptor subtype is involved in the expression of VEGF in primary rat gastric fibroblasts. PGE2 stimulated VEGF protein expression in the fibroblasts in a time- and dose-dependent manner. The up-regulation by PGE2 of VEGF expression was completely inhibited by a subtype selective EP4 receptor antagonist (AE3-208). Furthermore, the selective EP4 receptor agonist, AE1-329, promoted VEGF expression in the fibroblasts, and this effect was also totally antagonized by AE3-208. These results suggest that PGE2 stimulates VEGF expression in gastric fibroblasts through the activation of EP4 receptors, and this effect may be involved in the healing promoting action of PGE2 on gastric ulcers.

The angiogenic pathway "vascular endothelial growth factor/flk-1(KDR)-receptor" in rheumatoid arthritis and osteoarthritis.

Active angiogenesis, together with an up-regulation of angiogenic factors, is evident in the synovium of both rheumatoid arthritis (RA) and osteoarthritis (OA). The present study assessed, by immunohistochemistry, the microvessel density in the synovium of these arthritides and in normal controls, in relation to the expression of the angiogenic factors vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) and the apoptosis-related proteins bcl-2 and p53. More importantly, using the novel 11B5 MAb, the activated "VEGF/flk-1(KDR)-receptor" microvessel density was assessed. VEGF expression in fibroblasts was diffuse in both RA and OA. Diffuse PD-ECGF expression of fibroblasts was noted in all cases of RA, while fibroblast reactivity was focal in the OA material. The standard microvessel density (sMVD), as assessed with the anti-CD31 monoclonal antibody (MAb), was higher in RA (64+/-12) and in OA (65+/-16) than in normal tissues (52+/-8; p=0.008 and 0.0004, respectively). The activated microvessel density (aMVD), assessed with the 11B5 MAb, was significantly higher in RA (29+/-10) than in OA (17+/-4; p<0.0001) and than in normal tissues (14+/-2; p<0.0001). The "activation ratio" (aMVD/sMVD) was statistically higher in RA (0.46+/-0.17) than in OA and normal synovial tissues, the latter two having a similar ratio (0.28+/-0.08 and 0.26+/-0.03, respectively). Cytoplasmic bcl-2 expression was frequent in the synovial cells of OA, but rare in RA. Nuclear p53 protein accumulation was never observed. It is suggested that the angiogenic pathway VEGF/flk-1(KDR) may play an important role in the pathogenesis of RA and OA. Thus, failure of VEGF/flk-1(KDR) activation, in the presence of increased VEGF expression, may indicate a synovium with an impaired capacity to establish a viable vasculature, consistent with the degenerative nature of OA. On the other hand, the activated angiogenesis in RA shows a functional, still pathologically up-regulated VEGF/flk-1(KDR) pathway. Whether restoration of an impaired VEGF/flk-1(KDR) pathway in OA, or inhibition of this in RA, would prove of therapeutic importance requires further investigation.