Distinct roles of SOX9 in self-renewal of progenitors and mesenchymal transition of the endothelium.

Regenerative capabilities of the endothelium rely on vessel-resident progenitors termed endothelial colony forming cells (ECFCs). This study aimed to investigate if these progenitors are impacted by conditions (i.e., obesity or atherosclerosis) characterized by increased serum levels of oxidized low-density lipoprotein (oxLDL), a known inducer of Endothelial-to-Mesenchymal Transition (EndMT). Our investigation focused on understanding the effects of EndMT on the self-renewal capabilities of progenitors and the associated molecular alterations. In the presence of oxLDL, ECFCs displayed classical features of EndMT, through reduced endothelial gene and protein expression, function as well as increased mesenchymal genes, contractility, and motility. Additionally, ECFCs displayed a dramatic loss in self-renewal capacity in the presence of oxLDL. RNA-sequencing analysis of ECFCs exposed to oxLDL validated gene expression changes suggesting EndMT and identified SOX9 as one of the highly differentially expressed genes. ATAC sequencing analysis identified SOX9 binding sites associated with regions of dynamic chromosome accessibility resulting from oxLDL exposure, further pointing to its importance. EndMT phenotype and gene expression changes induced by oxLDL in vitro or high fat diet (HFD) in vivo were reversed by the silencing of SOX9 in ECFCs or the endothelial-specific conditional knockout of Sox9 in murine models. Overall, our findings support that EndMT affects vessel-resident endothelial progenitor's self-renewal. SOX9 activation is an early transcriptional event that drives the mesenchymal transition of endothelial progenitor cells. The identification of the molecular network driving EndMT in vessel-resident endothelial progenitors presents a new avenue in understanding and preventing a range of condition where this process is involved.

Resident vascular endothelial progenitor definition and function: the age of reckoning.

The cardiovascular system is composed around the central function of the endothelium that lines the inner surfaces of its vessels. In recent years, the existence of a progenitor population within the endothelium has been validated through the study of endothelial colony-forming cells (ECFCs) in human peripheral blood and certain vascular beds. However, our knowledge on endothelial populations in vivo that can give rise to ECFCs in culture has been limited. In this review we report and analyse recent attempts at describing progenitor populations in vivo from murine studies that reflect the self-renewal and stemness capacity observed in ECFCs. We pinpoint seminal discoveries within the field, which have phenotypically defined, and functionally scrutinised these endothelial progenitors. Furthermore, we review recent publications utilising single-cell sequencing technologies to better understand the endothelium in homeostasis and pathology.

Effect of intravenous thrombolysis combined with mild hypothermia on the levels of IL-1ß, IL-6, ICAM-1 and MMP-2 in patients with acute cerebral infarction and clinical significance.

The present study aimed to explore the effects and clinical importance of serum interleukin (IL) IL-1ß, IL-6, C-reactive protein (CRP), intercellular adhesion molecule (ICAM)-1 and matrix metalloproteinase (MMP)-2 in patients with acute cerebral infarction undergoing intravenous thrombolysis during simultaneous hypothermia therapy. A total of 80 patients with acute cerebral infarction who were treated at our hospital were randomly selected. They were divided into groups A and B. The two groups were treated with intravenous thrombolysis, while group B received sub-hypothermia treatment. Prior to treatment and at 7 days after treatment, 5 ml of venous blood was collected and stored in a freezer at -80˚C. IL-1ß, IL-6, CRP, ICAM-1 and MMP-2 levels were detected by ELISA and compared between the groups and time-points. The results were as follows: i) At 7 days after treatment, the levels of IL-1ß, IL-6, CRP, ICAM-1 and MMP-2 in group B were significantly decreased compared with those in group A (P<0.05), while there was no significant difference of these levels between group A and B before treatment (P>0.05). The incidence of adverse reactions in group A and group B was 35 and 20% respectively, and the mortality rate was 10 and 5%, respectively. There were no significant differences in adverse events and mortality between the two groups (P>0.05). In addition, a positive correlation of the level of IL-1ß, IL-6, CRP, ICAM-1 and MMP-2 with the National Institutes of Health Stroke Scale score was determined in the patients prior to treatment. In conclusion, mild hypothermia treatment in addition to intravenous thrombolysis significantly reduced the levels of IL-1ß, IL-6, CRP, ICAM-1 and MMP-2 in patients with acute cerebral infarction and reduced inflammation, and should therefore be incorporated in clinical practice.

Sox9 and Rbpj differentially regulate endothelial to mesenchymal transition and wound scarring in murine endovascular progenitors.

Endothelial to mesenchymal transition (EndMT) is a leading cause of fibrosis and disease, however its mechanism has yet to be elucidated. The endothelium possesses a profound regenerative capacity to adapt and reorganize that is attributed to a population of vessel-resident endovascular progenitors (EVP) governing an endothelial hierarchy. Here, using fate analysis, we show that two transcription factors SOX9 and RBPJ specifically affect the murine EVP numbers and regulate lineage specification. Conditional knock-out of Sox9 from the vasculature (Sox9fl/fl/Cdh5-CreER RosaYFP) depletes EVP while enhancing Rbpj expression and canonical Notch signalling. Additionally, skin wound analysis from Sox9 conditional knock-out mice demonstrates a significant reduction in pathological EndMT resulting in reduced scar area. The converse is observed with Rbpj conditionally knocked-out from the murine vasculature (Rbpjfl/fl/Cdh5-CreER RosaYFP) or inhibition of Notch signaling in human endothelial colony forming cells, resulting in enhanced Sox9 and EndMT related gene (Snail, Slug, Twist1, Twist2, TGF-ß) expression. Similarly, increased endothelial hedgehog signaling (Ptch1fl/fl/Cdh5-CreER RosaYFP), that upregulates the expression of Sox9 in cells undergoing pathological EndMT, also results in excess fibrosis. Endothelial cells transitioning to a mesenchymal fate express increased Sox9, reduced Rbpj and enhanced EndMT. Importantly, using topical administration of siRNA against Sox9 on skin wounds can substantially reduce scar area by blocking pathological EndMT. Overall, here we report distinct fates of EVPs according to the relative expression of Rbpj or Notch signalling and Sox9, highlighting their potential plasticity and opening exciting avenues for more effective therapies in fibrotic diseases.

Panaxatriol Saponins Promote M2 Polarization of BV2 Cells to Reduce Inflammation and Apoptosis after Glucose/Oxygen Deprivation by Activating STAT3.

Panaxatriol saponins (PTS) have a long history in the treatment of stroke. In our previous experiments, PTS has been found to alleviate ischemic stroke and play a role through regulating the inflammatory response, but the specific mechanism of its regulation is still unclear. Cell viability was determined by MTT assay. Expressions of polarization-related proteins CD16, CD68, ARG1 and CD206; inflammatory factors interleukin-1ß (IL-1ß); inducible nitric oxide synthase (iNOS); monocyte chemotactic protein 1(MCP-1) and cyclooxygenase-2 (COX-2); apoptosis-related proteins pro-caspase3; bax; caspase3 and bcl-2; and STAT3 and p-STAT3 were detected by western blot. ELISA was used to detect the expression of inflammatory-related factors in cells. The apoptosis rate was detected by flow cytometry. We found that the survival rate of oxygen sugar deprivation/reoxygenation (OGD/R) cells increased obviously after PTS treatment in a dose-dependent manner. PTS can promote M2 polarization of microglial cells (BV2) and inhibit inflammatory response of OGD/R cells, accompanied by decreased expression of inflammatory factors IL-1ß, iNOS, MCP-1, and COX-2. PTS inhibited apoptosis of OGD/R cells and was accompanied by decreased expression of apoptotic proteins Bax and caspase3 and increased expression of Bcl-2. We also found that PTS activated STAT3 levels in BV2 cells. After the addition of STAT3 inhibitor Stattic, it was found that PTS could promote M2 polarization of BV2 cells by activating the STAT3 pathway, thus inhibiting cell inflammation and apoptosis. PTS promoted M2 polarization in microglia cells by activating the STAT3 pathway, thereby reducing cell inflammation and apoptosis after glucose/oxygen deprivation.