17ß-Estradiol Regulates mTORC2 Sensitivity to Rapamycin in Adaptive Cardiac Remodeling

Adaptive cardiac remodeling is characterized by enhanced signaling of mTORC2 downstream kinase Akt. In females, 17ß-estradiol (E2), as well as Akt contribute essentially to sex-related premenopausal cardioprotection. Pharmacologic mTOR targeting with rapamycin is increasingly used for various clinical indications, yet burdened with clinical heterogeneity in therapy responses. The drug inhibits mTORC1 and less-so mTORC2. In male rodents, rapamycin decreases maladaptive cardiac hypertrophy whereas it leads to detrimental dilative cardiomyopathy in females. We hypothesized that mTOR inhibition could interfere with 17β-estradiol (E2)-mediated sexual dimorphism and adaptive cell growth and tested responses in murine female hearts and cultured female cardiomyocytes. Under physiological in vivo conditions, rapamycin compromised mTORC2 function only in female, but not in male murine hearts. In cultured female cardiomyocytes, rapamycin impaired simultaneously IGF-1 induced activation of both mTOR signaling branches, mTORC1 and mTORC2 only in presence of E2. Use of specific estrogen receptor (ER)α- and ERβ-agonists indicated involvement of both estrogen receptors (ER) in rapamycin effects on mTORC1 and mTORC2. Classical feedback mechanisms common in tumour cells with upregulation of PI3K signaling were not involved. E2 effect on Akt-pS473 downregulation by rapamycin was independent of ERK as shown by sequential mTOR and MEK-inhibition. Furthermore, regulatory mTORC2 complex defining component rictor phosphorylation at Ser1235, known to interfere with Akt-substrate binding to mTORC2, was not altered. Functionally, rapamycin significantly reduced trophic effect of E2 on cell size. In addition, cardiomyocytes with reduced Akt-pS473 under rapamycin treatment displayed decreased SERCA2A mRNA and protein expression suggesting negative functional consequences on cardiomyocyte contractility. Rictor silencing confirmed regulation of SERCA2A expression by mTORC2 in E2-cultured female cardiomyocytes. These data highlight a novel modulatory function of E2 on rapamycin effect on mTORC2 in female cardiomyocytes and regulation of SERCA2A expression by mTORC2. Conceivably, rapamycin abrogates the premenopausal “female advantage”

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

Expanded Hemodialysis ameliorates uremia-induced impairment of vasculoprotective KLF2 and concomitant proinflammatory priming of endothelial cells through an ERK/AP1/cFOS-dependent mechanism

AimsExpanded hemodialysis (HDx) therapy with improved molecular cut-off dialyzers exerts beneficial effects on lowering uremia-associated chronic systemic microinflammation, a driver of endothelial dysfunction and cardiovascular disease (CVD) in hemodialysis (HD) patients with end-stage renal disease (ESRD). However, studies on the underlying molecular mechanisms are still at an early stage. Here, we identify the (endothelial) transcription factor Krüppel-like factor 2 (KLF2) and its associated molecular signalling pathways as key targets and regulators of uremia-induced endothelial micro-inflammation in the HD/ESRD setting, which is crucial for vascular homeostasis and controlling detrimental vascular inflammation.Methods and resultsFirst, we found that human microvascular endothelial cells (HMECs) and other typical endothelial and kidney model cell lines (e.g. HUVECs, HREC, and HEK) exposed to uremic serum from patients treated with two different hemodialysis regimens in the Permeability Enhancement to Reduce Chronic Inflammation II (PERCI-II) crossover clinical trial - comparing High-Flux (HF) and Medium Cut-Off (MCO) membranes - exhibited strongly reduced expression of vasculoprotective KLF2 with HF dialyzers, while dialysis with MCO dialyzers led to the maintenance and restoration of physiological KLF2 levels in HMECs. Mechanistic follow-up revealed that the strong downmodulation of KLF2 in HMECs exposed to uremic serum was mediated by a dominant engagement of detrimental ERK instead of beneficial AKT signalling, with subsequent AP1-/c-FOS binding in the KLF2 promoter region, followed by the detrimental triggering of pleiotropic inflammatory mediators, while the introduction of a KLF2 overexpression plasmid could restore physiological KLF2 levels and downmodulate the detrimental vascular inflammation in a mechanistic rescue approach.ConclusionUremia downmodulates vasculoprotective KLF2 in endothelium, leading to detrimental vascular inflammation, while MCO dialysis with the novel improved HDx therapy approach can maintain physiological levels of vasculoprotective KLF2

A Systematic Review of Phase II Targeted Therapy Clinical Trials in Anaplastic Thyroid Cancer

Anaplastic thyroid carcinoma (ATC) is a rare, but devastating disease. Despite multimodal approaches combining surgery, chemotherapy and radiation therapy, ATC is associated with a dire prognosis, with a median overall survival of only three to ten months. Novel treatments are thus urgently needed. Recent efforts towards the characterization of the molecular landscape of ATC have led to the identification of pro-oncogenic targetable alterations, lending promise for novel targeted therapeutic approaches. This systematic review summarizes the results of phase II clinical trials of targeted therapy in ATC, providing an overview of efficacy and safety profiles. The majority of trials to date have consisted of small single-arm studies and have presented modest results. However, only a minority of trials have selected or stratified patients by molecular alterations. In the setting of BRAF V600E mutated ATC, dabrafenib/trametinib combination therapy and vemurafenib monotherapy have both demonstrated efficacy. Everolimus has furthermore shown promising results in patients with PI3K/mTOR/AKT pathway alterations. These studies underscore the importance of molecular profiling of tumors for appropriate patient selection and determination of genomic correlates of response. Clinical trials are underway testing additional targeted therapies as monotherapy, or as a part of multimodal treatment, and in combination with immunotherapy

Paediatric Virology and its interaction between basic science and clinical practice

The 3rd Workshop on Paediatric Virology, which took place on October 7th, 2017 in Athens, Greece, highlighted the role of breast feeding in the prevention of viral infections during the first years of life. Moreover, it focused on the long-term outcomes of respiratory syncytial virus and rhinovirus infections in prematurely born infants and emphasised the necessity for the development of relevant preventative strategies. Other topics that were covered included the vaccination policy in relation to the migration crisis, mother-to-child transmission of hepatitis B and C viruses, vaccination against human papilloma viruses in boys and advances on intranasal live-attenuated vaccination against influenza. Emphasis was also given to the role of probiotics in the management of viral infections in childhood, the potential association between viral infections and the pathogenesis of asthma, fetal and neonatal brain imaging and the paediatric intensive care of children with central nervous system viral infections. Moreover, an interesting overview of the viral causes of perinatal mortality in ancient Greece was given, where recent archaeological findings from the Athenian Agora's bone well were presented. Finally, different continuing medical educational options in Paediatric Virology were analysed and evaluated. The present review provides an update of the key topics discussed during the workshop