Genetic Variation in the CYP2C Monooxygenase Enzyme Subfamily Shows No Association With Longevity in a German Population

Cytochrome P450 enzymes, especially the CYP2C subfamily, are involved in the generation of reactive oxygen species and are regarded as susceptibility factors for age-related diseases. Furthermore, the CYP2C-encoding genes are known to be highly polymorphic, with a number of variants leading to changes in enzyme activity. These observations prompted us to investigate whether allelic variation in the CYP2C-encoding genes was associated with human longevity. In a comprehensive haplotype tagging approach, we genotyped 56 single nucleotide polymorphisms located in the CYP2C gene family (CYP2C8, CYP2C9, CYP2C18, and CYP2C19) in our extensive collection of 1,384 long-lived individuals (centenarians and nonagenarians) and 945 younger controls. None of the tested single nucleotide polymorphisms showed a significant association with the longevity phenotype at the allele, genotype, or haplotype level. These results suggest that there is no notable influence of sequence variation in the CYP2C genes on longevity in the examined German populatio

Understanding, diagnosing, and treating Myalgic encephalomyelitis/chronic fatigue syndrome - State of the art: Report of the 2nd international meeting at the Charité fatigue center.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a devastating disease affecting millions of people worldwide. Due to the 2019 pandemic of coronavirus disease (COVID-19), we are facing a significant increase of ME/CFS prevalence. On May 11th to 12th, 2023, the second international ME/CFS conference of the Charité Fatigue Center was held in Berlin, Germany, focusing on pathomechanisms, diagnosis, and treatment. During the two-day conference, more than 100 researchers from various research fields met on-site and over 700 attendees participated online to discuss the state of the art and novel findings in this field. Key topics from the conference included: the role of the immune system, dysfunction of endothelial and autonomic nervous system, and viral reactivation. Furthermore, there were presentations on innovative diagnostic measures and assessments for this complex disease, cutting-edge treatment approaches, and clinical studies. Despite the increased public attention due to the COVID-19 pandemic, the subsequent rise of Long COVID-19 cases, and the rise of funding opportunities to unravel the pathomechanisms underlying ME/CFS, this severe disease remains highly underresearched. Future adequately funded research efforts are needed to further explore the disease etiology and to identify diagnostic markers and targeted therapies

Feedback inhibition of prednisolone on vasopressin (AVP) secretion but preserved renal water reabsorption after thirsting point to an AVP-independent antidiuretic action

Lange wurde angenommen, dass allein das Antidiuretische Hormon (ADH) nach Bindung am Vasopressin-2-Rezeptor (V2R) über eine intrazelluläre cAMP-Erhöhung die Translokation von Aquaporin-2 (AQP2) in die apikale Zellmembran der Prinzipalzellen des Sammelrohrs bewirkt. Allerdings wurde 2006 eine ADH- unabhängige renale Wasserrückresorption unter exogener Glucocorticoidzufuhr beschrieben. Die Ziele der vorliegenden Arbeit waren (1) die Suppression des Plasma-ADH unter exogener Glucocorticoidzufuhr an einer größeren Probandenzahl in vivo zu überprüfen, (2) die ADH-unabhängige Antidiurese zu bestätigen und (3) die biophysiologischen Vorgänge einer ADH-unabhängigen renalen Wasser¬rückresorption zu untersuchen. Um den negativen Feedback von exogenen Glucocorticoiden auf die ADH-Sekretion zu untersuchen, wurden an 12 Probanden standardisierte Durstversuche durchgeführt. Auf einen basalen Durstversuch ohne Medikamenten¬einnahme folgten zwei weitere Durstversuche am ersten und letzten Tag einer fünftägigen Einnahme von 30 mg/d Prednisolon oral. Für die Beurteilung der intrazellulären AQP2-Translokation wurde die Ausscheidung von urinary-AQP2 (u AQP2) im Urin bestimmt. Im Anschluss an das achtstündige Dursten wurden jeweils 4 µg des V2R-Agonisten Desmopressinacetat i.v. appliziert. Im basalen Durstversuch stieg das Plasma-ADH signifikant von 0,45 0,09 auf 1,79 0,15 pg/ml an. Unter Prednisolon stieg es auch nach achtstündigem Dursten nicht über die Nachweisgrenze des Radioimmunossays von 0,4 pg/ml an. Keine signifikanten Unterschiede gab es beim Anstieg der Plasmaosmolalität, der jeweils 8,1 % betrug. Trotz des supprimierten Plasma- ADH wurde der Urin im Tagesverlauf konzentriert. Die Prednisoloneinnahme hatte keinen Einfluss auf die Ausscheidung von u AQP2 während des Durstens. Nach pharmakologischer Stimulation des V2R kam es unabhängig von der Prednisoloneinnahme zur signifikanten Steigerung der Ausscheidung von u AQP2. Unter Prednisoloneinnahme waren die Plasmaspiegel des Atrialen Natriuretischen Peptids (ANP) signifikant erhöht. In vitro wurde bereits gezeigt, dass ANP über einen cGMP-vermittelten Mechanismus die AQP2-Translokation in die apikale Zellmembran der renalen Sammelrohrzellen bewirken kann. Meine Daten unterstützen die Möglichkeit der Existenz des gleichen Mechanismus in vivo. Unter Prednisolon wurde zudem eine signifikante Aktivierung des Renin- Angiotensin-Aldosteron-Systems (RAAS) festgestellt. 2009 wurde ein mem¬bran¬ständiger Aldosteronrezeptor in renalen Sammelrohrzellen nachgewiesen, dessen Aktivierung dort eine cAMP-Erhöhung und damit die Translokation von AQP2 in die apikale Zellmembran bewirken kann. Über diesen Pathomechanismus könnte der erhöhte Aldosteron-Spiegel zur erhaltenen Antidiurese beigetragen haben. In dieser Arbeit wurde zusammenfassend gezeigt, dass es (1) unter Prednisolon zu einer signifikanten Supprimierung des Plasma- ADH mit (2) erhaltener AQP2-vermittelter renaler Antidiurese kam und (3) die zugrundeliegenden biophysiologischen Mechanismen der ADH-unabhängigen Wasserrückresoprtion folgendermaßen interpretiert werden können: Die Ergebnisse dieser Arbeit stützen die Hypothese, dass das Phänomen der ADH- unabhängigen Antidiurese auf den signifikant erhöhten Plasma-ANP-Spiegel zurückzuführen ist. Vermutlich induzierte ANP über cGMP die ADH-unabhängige Translokation von AQP2 in die apikale Zellmembran. Unterstützend könnte der beobachtet Aldosteron-Anstieg über cAMP ebenfalls den Einbau von AQP2 bewirkt haben.Adrenal insufficiency can result in severe hyponatremia due to inappropriate high plasma vasopressin (pAVP). To elucidate the glucocorticoid AVP feedback we monitored thirsting of 12 male volunteers without and after on or five days of prednisolone (30mg/d). Although prednisolone suppressed pAVP below 0.4 pg/ml the rise in plasma osmolality during thirsting was not influenced by prednisolone. Independent of exogenous glucocorticoid thirsting resulted in higher urine osmolality and decreased urine volume. Although pAVP was extremely low there was no difference in urinary secretion of aquaporin-2 (AQP2). Exogenous stimulation of the AVP V2 receptor by 4 µg desmopressin resulted in normal renal response with increased urine osmolality and decreased urine volume. The V2 agonist induced a significant increase of urinary AQP2 secretion. This increase is independent of prednisolone intake and suggests that AVP is able to act normally on the translocation of the water channel AQP2 in the principal cells of the collecting duct, compatible with our data of a prednisolone unrestricted rise in urinary cAMP excretion after desmopressin injection. Evidence has been reported that both secretion of atrial natriuretic peptide (ANP) and synthesis of prostaglandin E2 (PGE2) are influenced by the action of glucocorticoids and that they may modulate renal AVP action. In this study urinary excretion of PGE2 was not influenced by prednisolone intake. Plasma ANP concentration were higher during prednisolone treatment. An AVP independent effect of elevated ANP on AQP2 translocation would be compatible with the reported phosphorylation of AQP2 at Ser256 by protein kinase G (PKG) and subsequent AQP2 membrane translocation. The experiments show a strong feedback inhibition of the glucocorticoid prednisolone on AVP secretion. Preserved renal water reabsorption after thirsting in the presence of prednisolone suggests an AVP independent mechanism that may be influenced by higher ANP plasma concentrations

A P2rx7 Passenger Mutation Affects the Vitality and Function of T cells in Congenic Mice

International audienceAmong laboratory mouse strains many genes are differentially expressed in the same cell population. As consequence, gene targeting in 129-derived embryonic stem cells (ESCs) and backcrossing the modified mice onto the C57BL/6 background can introduce passenger mutations in the close proximity of the targeted gene. Here, we demonstrate that several transgenic mice carry a P2rx7 passenger mutation that affects the function of T cells. By the example of P2rx4 tm1Rass we demonstrate that P2X4ko T cells express higher levels of P2X7 and are more sensitive toward the P2X7 activators ATP and NAD + , rendering these cells more vulnerable toward NAD-induced cell death (NICD) compared with wild type (WT). The enhanced NICD sensitivity confounded functional assays e.g. cytokine production and cell migration. Our results need to be considered when working with P2rx4 tm1Rass mice or other 129-based transgenic strains that target P2rx7 neighboring genes

IA-PACS-CFS: a double-blinded, randomized, sham-controlled, exploratory trial of immunoadsorption in patients with chronic fatigue syndrome (CFS) including patients with post-acute COVID-19 CFS (PACS-CFS)

Abstract Background Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a severely debilitating condition which markedly restricts activity and function of affected people. Since the beginning of the COVID-19 pandemic ME/CFS related to post-acute COVID-19 syndrome (PACS) can be diagnosed in a subset of patients presenting with persistent fatigue 6 months after a mostly mild SARS-CoV-2 infection by fulfillment of the Canadian Consensus Criteria (CCC 2003). Induction of autoimmunity after viral infection is a mechanism under intensive investigation. In patients with ME/CFS, autoantibodies against thyreoperoxidase (TPO), beta-adrenergic receptors (ß2AR), and muscarinic acetylcholine receptors (MAR) are frequently found, and there is evidence for effectiveness of immunomodulation with B cell depleting therapy, cyclophosphamide, or intravenous immunoglobulins (IVIG). Preliminary studies on the treatment of ME/CFS patients with immunoadsorption (IA), an apheresis that removes antibodies from plasma, suggest clinical improvement. However, evidence from placebo-controlled trials is currently missing. Methods In this double-blinded, randomized, sham-controlled, exploratory trial the therapeutic effect of five cycles of IA every other day in patients with ME/CFS, including patients with post-acute COVID-19 chronic fatigue syndrome (PACS-CFS), will be evaluated using the validated Chalder Fatigue Scale, a patient-reported outcome measurement. A total of 66 patients will be randomized at a 2:1 ratio: 44 patients will receive IA (active treatment group) and 22 patients will receive a sham apheresis (control group). Moreover, safety, tolerability, and the effect of IA on patient-reported outcome parameters, biomarker-related objectives, cognitive outcome measurements, and physical parameters will be assessed. Patients will be hospitalized at the clinical site from day 1 to day 10 to receive five IA treatments and medical visits. Four follow-up visits (including two visits at site and two visits via telephone call) at month 1 (day 30), 2 (day 60), 4 (day 120), and 6 (day 180; EOS, end of study visit) will take place. Discussion Although ME/CFS including PACS-CFS causes an immense individual, social, and economic burden, we lack efficient therapeutic options. The present study aims to investigate the efficacy of immunoadsorption and to contribute to the etiological understanding and establishment of diagnostic tools for ME/CFS. Trial registration Registration Number: NCT05710770 . Registered on 02 February 2023

Neuronal metabotropic glutamate receptor 8 protects against neurodegeneration in CNS inflammation

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with continuous neuronal loss. Treatment of clinical progression remains challenging due to lack of insights into inflammation-induced neurodegenerative pathways. Here, we show that an imbalance in the neuronal receptor interactome is driving glutamate excitotoxicity in neurons of MS patients and identify the MS risk-associated metabotropic glutamate receptor 8 (GRM8) as a decisive modulator. Mechanistically, GRM8 activation counteracted neuronal cAMP accumulation, thereby directly desensitizing the inositol 1,4,5-trisphosphate receptor (IP3R). This profoundly limited glutamate-induced calcium release from the endoplasmic reticulum and subsequent cell death. Notably, we found Grm8-deficient neurons to be more prone to glutamate excitotoxicity, whereas pharmacological activation of GRM8 augmented neuroprotection in mouse and human neurons as well as in a preclinical mouse model of MS. Thus, we demonstrate that GRM8 conveys neuronal resilience to CNS inflammation and is a promising neuroprotective target with broad therapeutic implications

TRPM4 cation channel mediates axonal and neuronal degeneration in experimental autoimmune encephalomyelitis and multiple sclerosis

In multiple sclerosis, an inflammatory disease of the central nervous system (CNS), axonal and neuronal loss are major causes for irreversible neurological disability. However, which molecules contribute to axonal and neuronal injury under inflammatory conditions remains largely unknown. Here we show that the transient receptor potential melastatin 4 (TRPM4) cation channel is crucial in this process. TRPM4 is expressed in mouse and human neuronal somata, but it is also expressed in axons in inflammatory CNS lesions in experimental autoimmune encephalomyelitis (EAE) in mice and in human multiple sclerosis tissue. Deficiency or pharmacological inhibition of TRPM4 using the antidiabetic drug glibenclamide resulted in reduced axonal and neuronal degeneration and attenuated clinical disease scores in EAE, but this occurred without altering EAE-relevant immune function. Furthermore, Trpm4(-/-) mouse neurons were protected against inflammatory effector mechanisms such as excitotoxic stress and energy deficiency in vitro. Electrophysiological recordings revealed TRPM4-dependent neuronal ion influx and oncotic cell swelling upon excitotoxic stimulation. Therefore, interference with TRPM4 could translate into a new neuroprotective treatment strategy