Proatherosklerotische Wechselwirkung von oxidativem Stress, Low-Density-Lipoprotein, Angiotensin II und Endothelin-1 in humanen Endothelzellen

Eine der häufigsten kardiovaskulären Erkrankungen ist die Atherosklerose. Bei der Entstehung einer Atherosklerose spielt eine Hyperlipoproteinämie eine entscheidende Rolle. Ein weiterer Faktor für die Entstehung kardiovaskulärer Erkrankungen ist ein hoher Blutdruck. In dieser Arbeit wurde eine mögliche Interaktion zwischen Lipoproteinen und den blutdruckregulierenden Endothelin- und Renin-Angiotensin-Systemen untersucht. Weiterführende Analysen erfolgten an Rezeptoren für die Aufnahme von nLDL und oxLDL. Abschließend wurden Signalwege untersucht, die durch nLDL und oxLDL aktiviert werden. Tierexperimentielle Untersuchungen in Aorten und Herzen fettreich gefütterter Wildtyp- Mäuse unterstützen die Zellkultur-Ergebnisse einer Induzierung des Endothelin-Systems durch erhöhte Lipoproteine. Zusammenfassend zeigt diese Arbeit neue Mechanismen der Interaktion von Lipoproteinen und blutdruckregulierenden Systemen in Endothelzellen. Die Rezeptoren scheinen dabei eine Schlüsselrolle zu spielen. Dies spricht für eine Potenzierung von Hyperlipoproteinämie und Hypertonie bei der Entstehung von Herz-Kreislauf-Erkrankungen

Renal Ischemia/Reperfusion Injury in Soluble Epoxide Hydrolase-Deficient Mice

Aim 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) are cytochrome P450 (CYP)-dependent eicosanoids that play opposite roles in the regulation of vascular tone, inflammation, and apoptosis. 20-HETE aggravates, whereas EETs ameliorate ischemia/reperfusion (I/R)-induced organ damage. EETs are rapidly metabolized to dihydroxyeicosatrienoic acids (DHETs) by the soluble epoxide hydrolase (sEH). We hypothesized that sEH gene (EPHX2) deletion would increase endogenous EET levels and thereby protect against I/R-induced acute kidney injury (AKI). Methods Kidney damage was evaluated in male wildtype (WT) and sEH-knockout (KO)-mice that underwent 22-min renal ischemia followed by two days of reperfusion. CYP-eicosanoids were analyzed by liquid chromatography tandem mass spectrometry. Results Contrary to our initial hypothesis, renal function declined more severely in sEH-KO mice as indicated by higher serum creatinine and urea levels. The sEH-KO-mice also featured stronger tubular lesion scores, tubular apoptosis, and inflammatory cell infiltration. Plasma and renal EET/DHET-ratios were higher in sEH-KO than WT mice, thus confirming the expected metabolic consequences of sEH deficiency. However, CYP-eicosanoid profiling also revealed that renal, but not plasma and hepatic, 20-HETE levels were significantly increased in sEH-KO compared to WT mice. In line with this finding, renal expression of Cyp4a12a, the murine 20-HETE-generating CYP-enzyme, was up-regulated both at the mRNA and protein level, and Cyp4a12a immunostaining was more intense in the renal arterioles of sEH-KO compared with WT mice. Conclusion These results indicate that the potential beneficial effects of reducing EET degradation were obliterated by a thus far unknown mechanism leading to kidney-specific up- regulation of 20-HETE formation in sEH-KO-mice

Angiogenic Role of Mesothelium-Derived Chemokine CXCL1 During Unfavorable Peritoneal Tissue Remodeling in Patients Receiving Peritoneal Dialysis as Renal Replacement Therapy

Peritoneal dialysis (PD) is a valuable 'home treatment' option, even more so during the ongoing Coronavirus pandemic. However, the long-term use of PD is limited by unfavourable tissue remodelling in the peritoneal membrane, which is associated with inflammation-induced angiogenesis. This appears to be driven primarily through vascular endothelial growth factor (VEGF), while the involvement of other angiogenic signaling pathways is still poorly understood. Here, we have identified the crucial contribution of mesothelial cell-derived angiogenic CXC chemokine ligand 1 (CXCL1) to peritoneal angiogenesis in PD. CXCL1 expression and peritoneal microvessel density were analysed in biopsies obtained by the International Peritoneal Biobank (NCT01893710 at www.clinicaltrials.gov), comparing 13 children with end-stage kidney disease before initiating PD to 43 children on chronic PD. The angiogenic potential of mesothelial cell-derived CXCL1 was assessed in vitro by measuring endothelial tube formation of human microvascular endothelial cells (HMECs) treated with conditioned medium from human peritoneal mesothelial cells (HPMCs) stimulated to release CXCL1 by treatment with either recombinant IL-17 or PD effluent. We found that the capillary density in the human peritoneum correlated with local CXCL1 expression. Both CXCL1 expression and microvessel density were higher in PD patients than in the age-matched patients prior to initiation of PD. Exposure of HMECs to recombinant CXCL1 or conditioned medium from IL-17-stimulated HPMCs resulted in increased endothelial tube formation, while selective inhibition of mesothelial CXCL1 production by specific antibodies or through silencing of relevant transcription factors abolished the proangiogenic effect of HPMC-conditioned medium. In conclusion, peritoneal mesothelium-derived CXCL1 promotes endothelial tube formation in vitro and associates with peritoneal microvessel density in uremic patients undergoing PD, thus providing novel targets for therapeutic intervention to prolong PD therapy

Proatherosklerotische Wechselwirkung von oxidativem Stress, Low-Density-Lipoprotein, Angiotensin II und Endothelin-1 in humanen Endothelzellen

Eine der häufigsten kardiovaskulären Erkrankungen ist die Atherosklerose. Bei der Entstehung einer Atherosklerose spielt eine Hyperlipoproteinämie eine entscheidende Rolle. Ein weiterer Faktor für die Entstehung kardiovaskulärer Erkrankungen ist ein hoher Blutdruck. In dieser Arbeit wurde eine mögliche Interaktion zwischen Lipoproteinen und den blutdruckregulierenden Endothelin- und Renin-Angiotensin-Systemen untersucht. Weiterführende Analysen erfolgten an Rezeptoren für die Aufnahme von nLDL und oxLDL. Abschließend wurden Signalwege untersucht, die durch nLDL und oxLDL aktiviert werden. Tierexperimentielle Untersuchungen in Aorten und Herzen fettreich gefütterter Wildtyp- Mäuse unterstützen die Zellkultur-Ergebnisse einer Induzierung des Endothelin-Systems durch erhöhte Lipoproteine. Zusammenfassend zeigt diese Arbeit neue Mechanismen der Interaktion von Lipoproteinen und blutdruckregulierenden Systemen in Endothelzellen. Die Rezeptoren scheinen dabei eine Schlüsselrolle zu spielen. Dies spricht für eine Potenzierung von Hyperlipoproteinämie und Hypertonie bei der Entstehung von Herz-Kreislauf-Erkrankungen

Proatherosklerotische Wechselwirkung von oxidativem Stress, Low-Density-Lipoprotein, Angiotensin II und Endothelin-1 in humanen Endothelzellen

Eine der häufigsten kardiovaskulären Erkrankungen ist die Atherosklerose. Bei der Entstehung einer Atherosklerose spielt eine Hyperlipoproteinämie eine entscheidende Rolle. Ein weiterer Faktor für die Entstehung kardiovaskulärer Erkrankungen ist ein hoher Blutdruck. In dieser Arbeit wurde eine mögliche Interaktion zwischen Lipoproteinen und den blutdruckregulierenden Endothelin- und Renin-Angiotensin-Systemen untersucht. Weiterführende Analysen erfolgten an Rezeptoren für die Aufnahme von nLDL und oxLDL. Abschließend wurden Signalwege untersucht, die durch nLDL und oxLDL aktiviert werden. Tierexperimentielle Untersuchungen in Aorten und Herzen fettreich gefütterter Wildtyp- Mäuse unterstützen die Zellkultur-Ergebnisse einer Induzierung des Endothelin-Systems durch erhöhte Lipoproteine. Zusammenfassend zeigt diese Arbeit neue Mechanismen der Interaktion von Lipoproteinen und blutdruckregulierenden Systemen in Endothelzellen. Die Rezeptoren scheinen dabei eine Schlüsselrolle zu spielen. Dies spricht für eine Potenzierung von Hyperlipoproteinämie und Hypertonie bei der Entstehung von Herz-Kreislauf-Erkrankungen

Hepatic oxylipin profiles in WT and sEH-KO mice.

<p>(A), (B): Metabolic deficiency of sEH resulted in decreased DiHOME/EpOME- (A) as well as 14,15-DHET/14,15-EET-ratios (B). (C), (D): The hepatic levels of 5- through 19-HETE (C) as well as the hepatic 20-HETE levels (D) were not different in WT and sEH-KO mice. Results are given as mean ± SEM (n = 5–6 per group). Statistically significant differences were observed as indicated: * p<0.05, ** p<0.01 vs WT.</p

sEH gene disruption enhanced I/R-induced tubular damage.

<p>(A): Representative images of PAS-stained sections of kidneys harvested two days after reperfusion or sham surgery (magnification 200×, scale bar: 50 μm). Images were taken at the border of cortex and outer medulla. Arrows indicate necrotic tubules, and asterisks indicate tubular casts. (B): Evaluation of Acute Tubular Necrosis (ATN) score. sEH-KO mice subjected to I/R injury showed significantly increased tubular damage compared to the WT I/R or uninephrectomized control groups. Data are given as mean ± SEM (n = 5 per group). ***p<0.001 vs WT.</p

Plasma oxylipin profiles in WT and sEH-KO mice.

<p>(A): The conversion of linoleic acid-derived epoxides (EpOMEs) to the corresponding vicinal diols (DiHOMEs) was reduced in sEH-KO compared to WT mice as indicated by the decreased DiHOME/EpOME-ratios. (B): The conversion of AA-derived epoxides (EETs) to the corresponding vicinal diols (DHETs) was reduced in sEH-KO compared to WT mice as indicated by the decreased DHET/EET-ratios. (C): The plasma levels of AA-derived 5- through 19-HETE were not different in WT and sEH-KO mice. (D): Plasma 20-HETE levels were significantly lower in sEH-KO compared with WT mice. Results are given as mean ± SEM (n = 5–6 per group). Statistically significant differences were observed as indicated: * p<0.05, ** p<0.01, ***p<0.001 vs WT.</p

Upregulation of renal Cyp4a12a expression in sEH-KO mice.

<p>(A): Quantification of Cyp4a12a mRNA expression in kidneys of WT and sEH-KO mice by TaqMan RT-PCR. (B): A representative Western blot comparing the renal expression of Cyp4a12a protein in WT and sEH-KO mice. (C): Quantification of immunoreactive bands showed 2.5-fold higher Cyp4a12a protein levels in the kidneys of sEH-KO compared to WT mice. Real time-PCR data (A) and Western blot data (C) are given as mean ± SEM (n = 5–7 group). Statistically significant differences were observed as indicated: * p<0.05 vs WT.</p

Intrarenal localization of Cyp4a12a protein expression.

<p>(A): Representative images of renal sections stained for Cyp4a12a by the immunofluorescence (magnification 200×; scale bar: 50 μm). sEH gene disruption resulted in upregulating the expression of Cyp4a12a in mouse kidneys compared to WT mouse. The signals were blocked by pre-saturating the peptide-specific Cyp4a12a antibody with the corresponding synthetic peptide. (B): Images of a renal section from sEH-KO mice showing how immunostaining relates to the underlying renal structures (magnification 200×; scale bar: 50 μm). Images were taken at the area of renal cortex. Cyp4a12a immunostaining was most intense in the renal vessels (arcuate, interlobar, and interlobular arteries). Faint but specific staining occurred in tubules. No staining was detectable in glomeruli.</p