Mechanical stretch induces vascular permeability factor in human mesangial cells: Mechanisms of signal transduction

Abstract

Hemodynamic abnormalities have been implicated in the pathogenesis of the increased glomerular permeability to protein of diabetic and other glomerulopathies. Vascular permeability factor (VPF) is one of the most powerful promoters of vascular permeability. We studied the effect of stretch on VPF production by human mesangial cells and the intracellular signaling pathways involved. The application of mechanical stretch (elongation 10%) for 6 h induced a 2.4-fold increase over control in the VPF mRNA level (P < 0.05). There was a corresponding 3-fold increase in VPF protein level by 12 h (P < 0.001), returning to the baseline by 24 h. Stretch-induced VPF secretion was partially prevented both by the protein kinase C (PKC) inhibitor H7 (50 M: 72% inhibition, P < 0.05) and by pretreatment with phorbol ester (phorbol-12-myristate-13 acetate 10 ؊7 M: 77% inhibition, P < 0.05). A variety of protein tyrosine kinase (PTK) inhibitors, genistein (20 g͞ml), herbimycin A (3.4 M), and a specific pp60 src peptide inhibitor (21 M) also significantly reduced, but did not entirely prevent, stretch-induced VPF protein secretion (respectively 63%, 80%, and 75% inhibition; P < 0.05 for all). The combination of both PKC and PTK inhibition completely abolished the VPF response to mechanical stretch (100% inhibition, P < 0.05). Stretch induces VPF gene expression and protein secretion in human mesangial cells via PKC-and PTK-dependent mechanisms.

Angiotensin converting enzyme inhibition reduces retinal overexpression of vascular endothelial growth factor and hyperpermeability in experimental diabetes

“…Epidemiological, clinical course and intervention studies have all shown a positive relation between blood pressure and both the incidence and progression of diabetic retinopathy [63±65]. Furthermore, cell stretch, an in vitro counterpart of hypertension leads to increased VEGF expression [66]. Thus, it is possible that the effects of ACE inhibition on vascular permeability and VEGF expression, as shown in our study, followed a reduction in systemic blood pressure rather than a specific effect on the RAS.…”

Angiotensin converting enzyme inhibiting therapy is associated with lower vitreous vascular endothelial growth factor concentrations in patients with proliferative diabetic retinopathy

“…Another factor identified in vitro that also could contribute to VEGF overexpression is cell stretch [31]. In the retina cell stretch can be caused by an increased intraocular pressure.…”

P38 mitogen-activated protein kinase mediates hexosamine-induced TGFβ1 mRNA expression in human mesangial cells

“…Human mesangial cells (HMC) were obtained from glomeruli isolated from tumour-free portions of tumour nephrectomy specimens or from donor kidneys unsuitable for transplantation by serial sieving of cortex after collagenase digestion as described previously [17]. In brief, after digestion with collagenase (type IV, 750 U/ml), the isolated glomeruli were seeded in culture flasks.…”

“…Cells did not stain for cytokeratin, factor VIII, common leukocyte antigen or Thy-1, excluding contamination of epithelial cells, endothelial cells, lymphomonocytes and human fibroblasts respectively. Studies were done between passage 4 and 7 while the cells retain all the morphological and immunofluorescent characteristics as described above [17]. Ethics approval was obtained by the Guy's Hospital Research Ethics Committee (London, United Kingdom) and written consent obtained from the patient.…”