| 1. |
- Richards, Mark, et al.
(författare)
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Claudin5 protects the peripheral endothelial barrier in an organ and vessel-type-specific manner
- 2022
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Dysfunctional and leaky blood vessels resulting from disruption of the endothelial cell (EC) barrier accompanies numerous diseases. The EC barrier is established through endothelial cell tight and adherens junctions. However, the expression pattern and precise contribution of different junctional proteins to the EC barrier is poorly understood. Here, we focus on organs with continuous endothelium to identify structural and functional in vivo characteristics of the EC barrier. Assembly of multiple single-cell RNAseq datasets into a single integrated database revealed the variability and commonalities of EC barrier patterning. Across tissues, Claudin5 exhibited diminishing expression along the arteriovenous axis, correlating with EC barrier integrity. Functional analysis identified tissue-specific differences in leakage properties and response to the leakage agonist histamine. Loss of Claudin5 enhanced histamine-induced leakage in an organotypic and vessel type-specific manner in an inducible, EC-specific, knock-out mouse. Mechanistically, Claudin5 loss left junction ultrastructure unaffected but altered its composition, with concomitant loss of zonula occludens-1 and upregulation of VE-Cadherin expression. These findings uncover the organ-specific organisation of the EC barrier and distinct importance of Claudin5 in different vascular beds, providing insights to modify EC barrier stability in a targeted, organ-specific manner.
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| 2. |
- Richards, Mark, et al.
(författare)
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Intra-vessel heterogeneity establishes enhanced sites of macromolecular leakage downstream of laminin alpha 5
- 2021
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Ingår i: Cell Reports. - : Cell Press. - 2211-1247. ; 35:12
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Tidskriftsartikel (refereegranskat)abstract
- Endothelial cells display heterogeneous properties based on location and function. How this heterogeneity influences endothelial barrier stability both between and within vessel subtypes is unexplored. In this study, we find that endothelial cells exhibit heterogeneous barrier properties on inter-organ and intra-vessel levels. Using intravital microscopy and sequential stimulation of the ear dermis with vascular endothelial growth factor-A (VEGFA) and/or histamine, we observe distinct, reappearing sites, common for both agonists, where leakage preferentially takes place. Through repetitive stimulation of the diaphragm and trachea, we find inter-organ conservation of such predetermined leakage sites. Qualitatively, predetermined sites display distinct leakage properties and enhanced barrier breakdown compared to less susceptible regions. Mechanistically, laminin alpha 5 is reduced at predetermined sites, which is linked to reduced junctional vascular endothelial (VE)-cadherin and enhanced VEGFA-induced VE-cadherin phosphorylation. These data highlight functional intra-vessel heterogeneity that defines predetermined sites with distinct leakage properties and that may disproportionately impact pathological vascular leakage.
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| 3. |
- Sjöberg, Elin, et al.
(författare)
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Endothelial VEGFR2-PLCγ signaling regulates vascular permeability and antitumor immunity through eNOS/Src
- 2023
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Ingår i: Journal of Clinical Investigation. - : American Society For Clinical Investigation. - 0021-9738 .- 1558-8238. ; 133:20
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Tidskriftsartikel (refereegranskat)abstract
- Endothelial phospholipase C gamma (PLC gamma) is essential for vascular development; however, its role in healthy, mature, or pathological vessels is unexplored. Here, we show that PLC gamma was prominently expressed in vessels of several human cancer forms, notably in renal cell carcinoma (RCC). High PLC gamma expression in clear cell RCC correlated with angiogenic activity and poor prognosis, while low expression correlated with immune cell activation. PLC gamma was induced downstream of vascular endothelial growth factor receptor 2 (VEGFR2) phosphosite Y1173 (pY1173). Heterozygous Vegfr2Y1173F/+ mice or mice lacking endothelial PLC gamma (Plcg1iECKO) exhibited a stabilized endothelial barrier and diminished vascular leakage. Barrier stabilization was accompanied by decreased expression of immunosuppressive cytokines, reduced infiltration of B cells, helper T cells and regulatory T cells, and improved response to chemo-and immunotherapy. Mechanistically, pY1173/PLC gamma signaling induced Ca2+/protein kinase C-dependent activation of endothelial nitric oxide synthase (eNOS), required for tyrosine nitration and activation of Src. Src-induced phosphorylation of VE-cadherin at Y685 was accompanied by disintegration of endothelial junctions. This pY1173/PLC gamma/eNOS/Src pathway was detected in both healthy and tumor vessels in Vegfr2Y1173F/+ mice, which displayed decreased activation of PLC gamma and eNOS and suppressed vascular leakage. Thus, we believe that we have identified a clinically relevant endothelial PLC gamma pathway downstream of VEGFR2 pY1173, which destabilizes the endothelial barrier and results in loss of antitumor immunity.
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