Biology subjects

Longchamp, A.

Publications and source records attributed to Longchamp, A..

8 recordsLinked to original sources

bioRxiv2024

Sulfur Amino Acid Restriction Enhances Exercise Capacity in Mice by Boosting Fat Oxidation

Dietary restriction of the sulfur-containing amino acids methionine and cysteine (SAAR) improves body composition, enhances insulin sensitivity, and extends lifespan; benefits seen also with endurance exercise. Yet, the impact of SAAR on skeletal muscle remains largely unexplored. Here we demonstrate that one week of SAAR in sedentary, young, male mice increases endurance exercise capacity. Indirect calorimetry showed that SAAR increased lipid oxidation at rest and delayed the onset of carbohydrate utilization during exercise. Transcriptomic analysis revealed increased expression of genes involved in fatty acid catabolism especially in glycolytic muscle following SAAR. These findings were functionally supported by increased fatty acid circulatory turnover flux and muscle {beta}-oxidation. Reducing lipid uptake from circulation through endothelial cell (EC)-specific CD36 deletion attenuated the running phenotype. Mechanistically, VEGF-signaling inhibition prevented exercise increases following SAAR, without affecting angiogenesis, implicating noncanonical VEGF signaling and EC CD36-dependent fatty acid transport in regulating exercise capacity by influencing muscle substrate availability.

physiology↗

bioRxiv2024

Optimization of liver graft function using a poly-pharmacological drug cocktail CEPT in a simulated transplant model

BackgroundThe number of patients in need of a liver transplant far exceeds the supply of available organs. This imbalance could be dramatically reduced should the donor organ pool be expanded by rendering marginal cases transplantable rather than discarded. The poly-pharmacological drug cocktail CEPT (Chroman-1, Emricasan, Polyamine, and Trans-ISRIB (integrated stress inhibitor)) has been found to improve the in-vitro viability of human pluripotent stem cells (hPSCs) following cryopreservation. It is worth exploring CEPTs ability to inhibit various apoptotic pathways and preserve cellular function for potentially mitigating warm ischemic stress of the anhepatic phase of graft implantation and promoting more rapid graft recovery following reperfusion with continuous treatment. MethodsRat livers without warm ischemia and CEPT supplementation are the healthy control: fresh (n=3) group. Room-temperature warm ischemia was used to replicate the anhepatic phase of graft implantation in the control (n=6) group and the experimental CEPT group (n=6) without and with CEPT supplementation, respectively. Transplantation was modeled by ex-vivo reperfusion at 37{degrees}C for six hours with Williams E-based hepatocyte culture media and with CEPT supplementation in the CEPT group. ResultsLivers treated with CEPT during warm ischemia and subsequent reperfusion have improved hepatocellular function as indicated by increased oxygen O2 utilization, stable pH, and improved cholangiocyte function indicated by the increased hourly rate of bile production. Furthermore, resistance, an endothelial injury marker, and caspase 3/7, an apoptotic marker, were lower. ConclusionTo improve the utilization of available donor livers, different stages of the organ transplantation process can be optimized. The anhepatic phase, which includes the period from the removal of the native liver from the recipient to the reperfusion of the donors graft liver through the portal vein during graft implantation, can be targeted using CEPT for mitigating warm ischemia-induced injury that occurs during vascular anastomosis. (S1 Fig: Graphical abstract)

bioengineering↗

bioRxiv2024

Impaired glycolysis in aged endothelial cells is associated with reduced neovascularisation upon tissue ischemia

The vascular system experiences an age-associated decline in tissue perfusion and response to ischemic diseases. The factors driving this age-associated neovascularization decline remain unclear. While old endothelial cells (ECs) adopt a pro-angiogenic gene expression profile, we observed a stark reduction in the proliferative capacity of old ECs, while migratory capabilities remain intact. This is paralleled by a drastic decline in glycolytic capacity and ATP production, which likely act as limiting factors to neovascularization. These findings may provide new strategies to restore EC function in aging, thereby improving organ resilience and extending health- and lifespan.

molecular biology↗

bioRxiv2022

Cystathionine gamma lyase overexpression enhances neovascularization through NAD-dependent mechanisms

ObjectiveHydrogen sulfide (H2S) is a proangiogenic gas produced primarily by the transsulfuration enzyme cystathionine-gamma-lyase (CGL). CGL-dependant H2S production is required for neovasculariation in models of peripheral arterial disease. However, the benefits of increasing endogenous CGL and its mechanism of action have yet to be elucidated. Methods10 weeks old male whole-body CGL overexpressing mice (CGLTg) and wild type littermates (C57BL/6J) were subjected to the hindlimb ischemia model. Functional recovery was assessed through treadmill exercise endurance testing, while ischemic leg perfusion recovery was measured by laser Doppler perfusion imaging and tissue immunohistochemistry. To examine angiogenic potential, aortic ring sprouting assay and post-natal mouse retinal vasculature development studies were performed. Lastly, comparative metabolomics, NAD+/NADH analysis, and quantitative real-time PCR were performed on WT and CGLTg gastrocnemius muscles. ResultsThe restoration of blood flow upon femoral ligation occurred more rapidly in CGLTg mice. CGLTg mice were able to run further and for longer compared to WT mice. In ischemic gastrocnemius, capillary density was increased in mice overexpressing CGL. Endothelial cell sprouting was increased in aorta isolated from CGLTg mice, especially when cultured in VEGF-only media. Metabolomics analysis demonstrated an increased presence of niacinamide, a precursor of nicotinamide adenine dinucleotide (NAD+/ NADH) in the muscle of CGLTg mice. Finally, CGL overexpression and NMN supplementation improved endothelial cell migration in vitro. ConclusionsTaken together, our results demonstrate that CGL overexpression improves the neovascularization of skeletal muscle upon hindlimb ischemia. These effects are mediated by changes in the NAD pathway, which improves endothelial cell migration.

physiology↗

bioRxiv2021

Hydrogen sulfide release via the ACE inhibitor Zofenopril prevents intimal hyperplasia in human vein segments and in a mouse model of carotid artery stenosis

ObjectivesHypertension is a major risk factor for intimal hyperplasia (IH) and restenosis following vascular and endovascular interventions. Pre-clinical studies suggest that hydrogen sulfide (H2S), an endogenous gasotransmitter, limits restenosis. While there is no clinically available pure H2S releasing compound, the sulfhydryl-containing angiotensin-converting enzyme inhibitor Zofenopril is a source of H2S. Here, we hypothesized that Zofenopril, due to H2S release, would be superior to other non-sulfhydryl containing angiotensin converting enzyme inhibitor (ACEi), in reducing intimal hyperplasia. MaterialsSpontaneously hypertensive male Cx40 deleted mice (Cx40-/-) or WT littermates were randomly treated with Enalapril 20 mg (Mepha Pharma) or Zofenopril 30 mg (Mylan SA). Discarded human vein segments and primary human smooth muscle cells (SMC) were treated with the active compound Enalaprilat or Zofenoprilat. MethodsIH was evaluated in mice 28 days after focal carotid artery stenosis surgery and in human vein segments cultured for 7 days ex vivo. Human primary smooth muscle cell (SMC) proliferation and migration were studied in vitro. ResultsCompared to control animals (intima/media thickness=2.3{+/-}0.33), Enalapril reduced IH in Cx40-/- hypertensive mice by 30% (1.7{+/-}0.35; p=0.037), while Zofenopril abrogated IH (0.4{+/-}0.16; p<.0015 vs. Ctrl and p>0.99 vs. sham-operated Cx40-/- mice). In WT normotensive mice, enalapril had no effect (0.9665{+/-}0.2 in control vs 1.140{+/-}0.27; p>.99), while Zofenopril also abrogated IH (0.1623{+/-}0.07, p<.008 vs. Ctrl and p>0.99 vs. sham-operated WT mice). Zofenoprilat, but not Enalaprilat, also prevented intimal hyperplasia in human veins segments ex vivo. The effect of Zofenopril on carotid and SMC correlated with reduced SMC proliferation and migration. Zofenoprilat inhibited the MAPK and mTOR pathways in SMC and human vein segments. ConclusionZofenopril provides extra beneficial effects compared to non-sulfhydryl ACEi to reduce SMC proliferation and restenosis, even in normotensive animals. These findings may hold broad clinical implications for patients suffering from vascular occlusive diseases and hypertension. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/460108v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@a37b62org.highwire.dtl.DTLVardef@f977e0org.highwire.dtl.DTLVardef@2d3266org.highwire.dtl.DTLVardef@147d604_HPS_FORMAT_FIGEXP M_FIG C_FIG What this paper addsThe current strategies to reduce intimal hyperplasia (IH) principally rely on local drug delivery, in endovascular approach. The oral angiotensin converting enzyme inhibitor (ACEi) Zofenopril has additional effects compared to other non-sulfyhydrated ACEi to prevent intimal hyperplasia and restenosis. Given the number of patients treated with ACEi worldwide, these findings call for further prospective clinical trials to test the benefits of sulfhydrated ACEi over classic ACEi for the prevention of restenosis in hypertensive patients.

physiology↗

bioRxiv2021

Sodium Thiosulfate acts as an H2S mimetic to prevent intimal hyperplasia via inhibition of tubulin polymerization

BackgroundIntimal hyperplasia (IH) remains a major limitation in the long-term success of any type of revascularization. IH is due to vascular smooth muscle cell (VSMC) dedifferentiation, proliferation and migration. The gasotransmitter Hydrogen Sulfide (H2S) inhibits IH in pre-clinical models. However, there is currently no clinically approved H2S donor. Here we used sodium thiosulfate (STS), a clinically-approved source of sulfur, to limit IH. MethodsHypercholesterolemic LDLR deleted (LDLR-/-), WT or CSE-/- male mice randomly treated with 4g/L STS in the water bottle were submitted to focal carotid artery stenosis to induce IH. Human vein segments were maintained in culture for 7 days to induce IH. Further in vitro studies were conducted in primary human vascular smooth muscle cell (VSMC). FindingsSTS inhibited IH in mice and in human vein segments. STS inhibited cell proliferation in the carotid artery wall and in human vein segments. STS increased polysulfides in vivo and protein persulfidation in vitro, which correlated with microtubule depolymerization, cell cycle arrest and reduced VSMC migration and proliferation. InterpretationSTS, a drug used for the treatment of cyanide poisoning and calciphylaxis, protects against IH in a mouse model of arterial restenosis and in human vein segments. STS acts as an H2S donor to limit VSMC migration and proliferation via microtubule depolymerization. FundingThis work was supported by the Swiss National Science Foundation (grant FN-310030_176158 to FA and SD and PZ00P3-185927 to AL); the Novartis Foundation to FA; and the Union des Societes Suisses des Maladies Vasculaires to SD. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/459573v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@c98479org.highwire.dtl.DTLVardef@1863f0org.highwire.dtl.DTLVardef@1492ad7org.highwire.dtl.DTLVardef@9bca8a_HPS_FORMAT_FIGEXP M_FIG C_FIG Research in contextO_ST_ABSEvidence before this studyC_ST_ABSIntimal hyperplasia (IH) is a complex process leading to vessel restenosis, a major complication following cardiovascular surgeries and angioplasties. Therapies to limit IH are currently limited. Pre-clinical studies suggest that hydrogen sulfide (H2S), an endogenous gasotransmitter, limits restenosis. However, despite these potent cardiovascular benefits in pre-clinical studies, H2S-based therapeutics are not available yet. Sodium thiosulfate (Na2S2O3) is an FDA-approved drug used for the treatment of cyanide poisoning and calciphylaxis, a rare condition of vascular calcification affecting patients with end-stage renal disease. Evidence suggest that thiosulfate may generate H2S in vivo in pre-clinical studies. Added value of this studyHere, we demonstrate that STS inhibit IH in a surgical mouse model of IH and in an ex vivo model of IH in human vein culture. We further found that STS increases circulating polysulfide levels in vivo and inhibits IH via decreased cell proliferation via disruption of the normal cells cytoskeleton. Finally, using CSE knockout mice, the main enzyme responsible for H2S production in the vasculature, we found that STS rescue these mice from accelerated IF formation. Implications of all the available evidenceThese findings suggest that STS holds strong translational potentials to limit IH following vascular surgeries and should be investigated further.

physiology↗

bioRxiv2020

ATF-4 and hydrogen sulfide signalling mediate longevity from inhibition of translation or mTORC1

Inhibition of the master growth regulator mTORC1 (mechanistic target of rapamycin complex 1) slows ageing across phyla, in part by reducing protein synthesis. Various stresses globally suppress protein synthesis through the integrated stress response (ISR), resulting in preferential translation of the transcription factor ATF-4. Here we show in C. elegans that inhibition of translation or mTORC1 increases ATF-4 expression, and that ATF-4 mediates longevity under these conditions independently of ISR signalling. ATF-4 promotes longevity by activating canonical anti-ageing mechanisms, but also by elevating expression of the transsulfuration enzyme CTH-2 to increase hydrogen sulfide (H2S) production. This H2S boost increases protein persulfidation, a protective modification of redox-reactive cysteines. The ATF-4/CTH-2/H2S pathway also mediates longevity and increased stress resistance from mTORC1 suppression. Increasing H2S levels, or enhancing mechanisms that H2S influences through persulfidation, may represent promising strategies for mobilising therapeutic benefits of the ISR, translation suppression, or mTORC1 inhibition.

physiology↗

bioRxiv2019

Impact of an intra-abdominal cooling device during open kidney transplantation in pigs

BackgroundKidney transplantation using deceased donors still suffers from high post-operative dysfunction rate. During implantation into the recipient, the kidney rewarms. This second warm ischemia time, which is not monitored, is harmful especially if prolonged. We recently developed an intra-abdominal cooling device that efficiently prevents kidney rewarming during robotic transplantation, and prevent ischemia-reperfusion injuries. Here, we tested the benefits of this cooling device during open kidney transplantation in pigs.\n\nMaterialsKidneys were procured from large pigs by open bilateral nephrectomy. Following procurement, kidneys were flushed with 4{degrees}C Institut Georges Lopez-1 preservation solution, and placed on ice for 128.5 {+/-} 23.2 min. The cooling device was used to continuously cool down the kidney during the vascular anastomosis time.\n\nMethodsAnimals underwent double sequential autologous open renal transplantation with (n = 7) and without (n = 6) intra-abdominal cooling. Renal cortex temperature and urine output were monitored. The severity of the ischemia reperfusion lesions was analyzed by histology (modified Goujon score).\n\nResultsMean anastomosis time was similar between groups (43.9 {+/-} 13 min). At reperfusion, the renal cortex temperature was lower in the group with cooling (4.3 {+/-} 1.1{degrees}C vs 26.5 {+/-} 5.5{degrees}C p <0.001). The cooled kidneys tended to be protected from injury, including some histopathological ischemia-reperfusion lesions. With the device, kidneys had a better immediate post-operative urine output (p=0.05).\n\nConclusionsOur results indicate that the intra-abdominal cooling device significantly reduces second warm ischemic time during transplantation, is technically safe, and does not prolong anastomotic time.

physiology↗