Phase 2 randomised placebo-controlled trial of spironolactone and dexamethasone versus dexamethasone in COVID-19 hospitalised patients in Delhi.

BACKGROUND: In this phase 2 randomised placebo-controlled clinical trial in patients with COVID-19, we hypothesised that blocking mineralocorticoid receptors using a combination of dexamethasone to suppress cortisol secretion and spironolactone is safe and may reduce illness severity. METHODS: Hospitalised patients with confirmed COVID-19 were randomly allocated to low dose oral spironolactone (50 mg day 1, then 25 mg once daily for 21 days) or standard of care in a 2:1 ratio. Both groups received dexamethasone 6 mg daily for 10 days. Group allocation was blinded to the patient and research team. Primary outcomes were time to recovery, defined as the number of days until patients achieved WHO Ordinal Scale (OS) category ≤ 3, and the effect of spironolactone on aldosterone, D-dimer, angiotensin II and Von Willebrand Factor (VWF). RESULTS: One hundred twenty patients with PCR confirmed COVID were recruited in Delhi from 01 February to 30 April 2021. 74 were randomly assigned to spironolactone and dexamethasone (SpiroDex), and 46 to dexamethasone alone (Dex). There was no significant difference in the time to recovery between SpiroDex and Dex groups (SpiroDex median 4.5 days, Dex median 5.5 days, p = 0.055). SpiroDex patients had significantly lower D-dimer levels on days 4 and 7 (day 7 mean D-dimer: SpiroDex 1.15 µg/mL, Dex 3.15 µg/mL, p = 0.0004) and aldosterone at day 7 (SpiroDex 6.8 ng/dL, Dex 14.52 ng/dL, p = 0.0075). There was no difference in VWF or angiotensin II levels between groups. For secondary outcomes, SpiroDex patients had a significantly greater number of oxygen free days and reached oxygen freedom sooner than the Dex group. Cough scores were no different during the acute illness, however the SpiroDex group had lower scores at day 28. There was no difference in corticosteroid levels between groups. There was no increase in adverse events in patients receiving SpiroDex. CONCLUSION: Low dose oral spironolactone in addition to dexamethasone was safe and reduced D-dimer and aldosterone. Time to recovery was not significantly reduced. Phase 3 randomised controlled trials with spironolactone and dexamethasone should be considered. TRIAL REGISTRATION: The trial was registered on the Clinical Trials Registry of India TRI: CTRI/2021/03/031721, reference: REF/2021/03/041472. Registered on 04/03/2021.

Computational Fluorescence Suppression in Shifted Excitation Raman Spectroscopy.

Fiber-based Raman spectroscopy in the context of in vivo biomedical application suffers from the presence of background fluorescence from the surrounding tissue that might mask the crucial but inherently weak Raman signatures. One method that has shown potential for suppressing the background to reveal the Raman spectra is shifted excitation Raman spectroscopy (SER). SER collects multiple emission spectra by shifting the excitation by small amounts and uses these spectra to computationally suppress the fluorescence background based on the principle that Raman spectrum shifts with excitation while fluorescence spectrum does not. We introduce a method that utilizes the spectral characteristics of the Raman and fluorescence spectra to estimate them more effectively, and compare this approach against existing methods on real world datasets.

Specific in situ immuno-imaging of pulmonary-resident memory lymphocytes in human lungs.

Introduction: Pulmonary-resident memory T cells (TRM) and B cells (BRM) orchestrate protective immunity to reinfection with respiratory pathogens. Developing methods for the in situ detection of these populations would benefit both research and clinical settings. Methods: To address this need, we developed a novel in situ immunolabelling approach combined with clinic-ready fibre-based optical endomicroscopy (OEM) to detect canonical markers of lymphocyte tissue residency in situ in human lungs undergoing ex vivo lung ventilation (EVLV). Results: Initially, cells from human lung digests (confirmed to contain TRM/BRM populations using flow cytometry) were stained with CD69 and CD103/CD20 fluorescent antibodies and imaged in vitro using KronoScan, demonstrating it's ability to detect antibody labelled cells. We next instilled these pre-labelled cells into human lungs undergoing EVLV and confirmed they could still be visualised using both fluorescence intensity and lifetime imaging against background lung architecture. Finally, we instilled fluorescent CD69 and CD103/CD20 antibodies directly into the lung and were able to detect TRM/BRM following in situ labelling within seconds of direct intra-alveolar delivery of microdoses of fluorescently labelled antibodies. Discussion: In situ, no wash, immunolabelling with intra-alveolar OEM imaging is a novel methodology with the potential to expand the experimental utility of EVLV and pre-clinical models.

Tri-mode optical biopsy probe with fluorescence endomicroscopy, Raman spectroscopy, and time-resolved fluorescence spectroscopy.

We present an endoscopic probe that combines three distinct optical fibre technologies including: A high-resolution imaging fibre for optical endomicroscopy, a multimode fibre for time-resolved fluorescence spectroscopy, and a hollow-core fibre with multimode signal collection cores for Raman spectroscopy. The three fibers are all enclosed within a 1.2 mm diameter clinical grade catheter with a 1.4 mm end cap. To demonstrate the probe's flexibility we provide data acquired with it in loops of radii down to 2 cm. We then use the probe in an anatomically accurate model of adult human airways, showing that it can be navigated to any part of the distal lung using a commercial bronchoscope. Finally, we present data acquired from fresh ex vivo human lung tissue. Our experiments show that this minimally invasive probe can deliver real-time optical biopsies from within the distal lung - simultaneously acquiring co-located high-resolution endomicroscopy and biochemical spectra.

Randomised controlled trial of intravenous nafamostat mesylate in COVID pneumonitis: Phase 1b/2a experimental study to investigate safety, Pharmacokinetics and Pharmacodynamics.

BACKGROUND: Many repurposed drugs have progressed rapidly to Phase 2 and 3 trials in COVID19 without characterisation of Pharmacokinetics /Pharmacodynamics including safety data. One such drug is nafamostat mesylate. METHODS: We present the findings of a phase Ib/IIa open label, platform randomised controlled trial of intravenous nafamostat in hospitalised patients with confirmed COVID-19 pneumonitis. Patients were assigned randomly to standard of care (SoC), nafamostat or an alternative therapy. Nafamostat was administered as an intravenous infusion at a dose of 0.2 mg/kg/h for a maximum of seven days. The analysis population included those who received any dose of the trial drug and all patients randomised to SoC. The primary outcomes of our trial were the safety and tolerability of intravenous nafamostat as an add on therapy for patients hospitalised with COVID-19 pneumonitis. FINDINGS: Data is reported from 42 patients, 21 of which were randomly assigned to receive intravenous nafamostat. 86% of nafamostat-treated patients experienced at least one AE compared to 57% of the SoC group. The nafamostat group were significantly more likely to experience at least one AE (posterior mean odds ratio 5.17, 95% credible interval (CI) 1.10 - 26.05) and developed significantly higher plasma creatinine levels (posterior mean difference 10.57 micromol/L, 95% CI 2.43-18.92). An average longer hospital stay was observed in nafamostat patients, alongside a lower rate of oxygen free days (rate ratio 0.55-95% CI 0.31-0.99, respectively). There were no other statistically significant differences in endpoints between nafamostat and SoC. PK data demonstrated that intravenous nafamostat was rapidly broken down to inactive metabolites. We observed no significant anticoagulant effects in thromboelastometry. INTERPRETATION: In hospitalised patients with COVID-19, we did not observe evidence of anti-inflammatory, anticoagulant or antiviral activity with intravenous nafamostat, and there were additional adverse events. FUNDING: DEFINE was funded by LifeArc (an independent medical research charity) under the STOPCOVID award to the University of Edinburgh. We also thank the Oxford University COVID-19 Research Response Fund (BRD00230).

Sub millimetre flexible fibre probe for background and fluorescence free Raman spectroscopy.

Using the shifted-excitation Raman difference spectroscopy technique and an optical fibre featuring a negative curvature excitation core and a coaxial ring of high numerical aperture collection cores, we have developed a portable, background and fluorescence free, endoscopic Raman probe. The probe consists of a single fibre with a diameter of less than 0.25 mm packaged in a sub-millimetre tubing, making it compatible with standard bronchoscopes. The Raman excitation light in the fibre is guided in air and therefore interacts little with silica, enabling an almost background free transmission of the excitation light. In addition, we used the shifted-excitation Raman difference spectroscopy technique and a tunable 785 nm laser to separate the fluorescence and the Raman spectrum from highly fluorescent samples, demonstrating the suitability of the probe for biomedical applications. Using this probe we also acquired fluorescence free human lung tissue data.

VPAC and PAC receptors: From ligands to function.

Vasoactive intestinal peptide (VIP) and the pituitary adenylate cyclase activating polypeptides (PACAPs) share 68% identity at the amino acid level and belong to the secretin peptide family. Following the initial discovery of VIP almost four decades ago a substantial amount of knowledge has been presented describing the mechanisms of action, distribution and pleiotropic functions of these related peptides. It is now known that the physiological actions of these widely distributed peptides are produced through activation of three common G-protein coupled receptors (VPAC(1), VPAC(2) and PAC(1)R) which preferentially stimulate adenylate cyclase and increase intracellular cAMP, although stimulation of other intracellular messengers, including calcium and phospholipase D, has been reported. Using a range of in vitro and in vivo approaches, including cell-based functional assays, transgenic animals and rodent models of disease, VPAC/PAC receptor activation has been associated with numerous physiological processes (e.g. control of circadian rhythms) and clinical conditions (e.g. pulmonary hypertension), which underlies on-going research efforts and makes these peptides and their cognate receptors attractive targets for the pharmaceutical industry. However, despite the considerable interest in VPAC/PAC receptors and the processes which they mediate, there is still a paucity of selective and available, non-peptide ligands, which has hindered further advances in this field both at the basic research and clinical level. This review summarises the current knowledge of VIP/PACAP and the VPAC/PAC receptors with regard to their distribution, pharmacology, signalling pathways, splice variants and finally, the utility of animal models in exploring their physiological roles.

Progressive impairment in olfactory working memory in a mouse model of Mild Cognitive Impairment.

Patients with Mild Cognitive Impairment (MCI), exhibiting both working memory and olfactory deficits are likely to progress to Alzheimer's disease (AD). Targeting this pre-clinical AD population with disease modifying agents or cognitive enhancers represents the best strategy for halting or delaying the impact of this pernicious disease. However, there is a paucity of animal models of MCI with which to assess putative therapeutic strategies. We describe an odour span task which assesses the ability of mice to remember lists of odours, and report subtle cognitive deficits in human amyloid over-expressing (Tg2576) mice, at an age prior to plaque deposition. Four-month-old Tg2576 mice exhibited normal acquisition and performance in the standard 12-span task, but were significantly impaired when memory load was increased to 22 odours. By 8-months, a performance deficit was apparent in the 12-span task and by 1-year mice also exhibited significant acquisition deficits. Thus, by assessing olfactory working memory in Tg2576 mice we can model aspects of MCI in rodents and aid development of future therapeutic strategies for AD.

Characterisation of the Bax-nucleophosmin interaction: the importance of the Bax C-terminus.

The molecular chaperone nucleophosmin has been identified as a novel Bax binding protein with this interaction proposed to be a key event in the activation and translocation of Bax in mitochondrial dysfunction and apoptotic cell death. Using a proximity assay, we have quantitatively defined the high affinity and saturable interaction between Bax and nucleophosmin indicative of a competitive and specific mechanism. Binding of full length Bax to nucleophosmin was only observed after conformational change was induced using non-ionic detergents (e.g., NP-40). The Bax-nucleophosmin interaction was inhibited by a Bax C-terminal antibody (IC(50) = 1 nM) but minimally affected by antibodies directed against either the N-terminus or alpha-helices 4 and 5. Bcl-2 and p53 inhibited the interaction between full length activated Bax and nucleophosmin. The proximity assay based on the Bax-nucleophosmin interaction was robust and reproducible (Z' = 0.50) facilitating its use for screening a small chemical library. A low molecular weight non-peptide compound, 2-(5-methyl-2-phenyl-1,3-thiazol-4-yl)ethanohydrazide, partially inhibited the Bax-nucleophosmin interaction (IC(50) = 100 nM) and also attenuated UV-induced cell death of HEK293 cells. The present investigations demonstrate the importance of exposure of the C-terminus of Bax for its interaction with nucleophosmin. These protein-protein interaction assays provide a technical approach both for the study of Bax-interacting proteins and for the discovery of novel anti-apoptotic agents.

The role of the purinergic P2X7 receptor in inflammation.

The inflammatory process, orchestrated against a variety of injurious stimuli, is composed of three inter-related phases; initiation, propagation and resolution. Understanding the interplay between these three phases and harnessing the beneficial properties of inflammation whilst preventing its damaging effects, will undoubtedly lead to the advent of much needed therapies, particularly in chronic disease states. The P2X7 receptor (P2X7R) is increasingly recognised as an important cell surface regulator of several key inflammatory molecules including IL-1beta, IL-18, TNF-alpha and IL-6. Moreover, as P2X7R-dependent cytokine production is driven by activating the inflammasome, antagonists of this receptor are likely to have therapeutic potential as novel anti-inflammatory therapies. The function of the P2X7R in inflammation, immunity and its potential role in disease will be reviewed and discussed.

Impaired attention is central to the cognitive deficits observed in alpha 7 deficient mice.

alpha7-Nicotinic acetylcholine receptors (alpha7-nAChR) have been implicated in a range of cognitive deficits in schizophrenia. Therefore we examined alpha7-nAChR knockout (KO), heterozygote (HT) and wildtype (WT) littermate mice in the 5-CSR (a rodent model of sustained attention) and odour span (a novel mouse working memory paradigm) tasks, and related performance to nAChR density. Whilst there was no difference between groups in baseline 5-CSR task performance, alpha7-nAChR KO's exhibited significantly higher omission levels compared to WT mice on increasing the attentional load, with HT mice performing at an intermediate level. Furthermore, alpha7-nAChR KO mice were significantly impaired in the odour span task when compared to WT mice, in a pattern consistent with impaired attention. These behavioural deficits were associated with the loss of alpha7-nAChRs, as alpha4beta2-nAChR density was unaltered in these mice. Thus these studies intimate that the attentional impairment in alpha7-nAChR transgenic mice maybe core to other deficits in cognition.

The odour span task: a novel paradigm for assessing working memory in mice.

Impoverished odour recognition and memory are amongst the earliest symptoms observed in mild cognitive impairment, Alzheimer's disease and schizophrenia, and have been advocated as early disease bio-markers. Although transgenic animals modelling disease pathologies continually emerge, there remains a paucity of tasks to examine olfactory working memory in mice. The present studies describe a mouse odour span task, which assesses the ability to remember increasing numbers of odours. Since caspase-3 is highly expressed throughout the olfactory system, we postulated that mice over-expressing this apoptogenic protein would exhibit impaired performance in the odour span task. Mice over-expressing human caspase-3 (Tg) exhibited age-independent deficits in olfactory working memory (6-18 months) compared with wild-type littermates, requiring longer for task acquisition and exhibiting impaired asymptotic performance, with reduced span lengths, lower accuracy and increased error rates. These impairments appeared to be selective for working memory, as Tg mice had no deficits in odour discriminatory ability or in locomotor measures. Importantly, nicotine, which improves working memory span in man, reversed the deficits exhibited by Tg mice. In conclusion, the mouse odour span task can detect subtle changes in olfactory working memory induced by genetic manipulation and drug administration and therefore should be applied to animal models of neurological disease.

VIP and PACAP receptor pharmacology: a comparison of intracellular signaling pathways.

VIP/PACAP receptor activation stimulates the production of [cAMP]i and [Ca2+]i by coupling to independent G-protein subunits, although agonist potencies for the different transduction pathways appear to differ. Using CHO-K1 cells stably expressing the human VIP/PACAP receptors (hVPAC1R, hVPAC2R, and hPAC1R), functional assays ([cAMP]i and [Ca2+]i) were established and the receptor pharmacology was characterized with five peptide agonists (VIP, PACAP-27, PACAP-38, [Ala(11,22,28)]VIP, and R3P65). The rank order of potency (ROP) was consistent between assays for the individual receptor subtypes, however, higher agonist concentrations (approximately 100-fold) were required for stimulating [Ca2+]i when compared to [cAMP]i.

A systematic comparison of intracellular cyclic AMP and calcium signalling highlights complexities in human VPAC/PAC receptor pharmacology.

VPAC/PAC receptor activation classically results in cyclic-AMP production, with limited reports evaluating calcium signalling. These studies systematically characterise intracellular cyclic-AMP ([cAMP](i)) and calcium ([Ca(2+)](i)) responses in CHO-cells expressing recombinant human (h) VPAC/PAC receptors (hVPAC(1)R, hVPAC(2)R, hPAC(1)R), using two simple, non-radioactive, HT-amenable assays. The rank order of potency (ROP) of the agonists VIP, PACAP-27 and PACAP-38 was similar in both assays for each individual receptor subtype, although potencies (EC(50)) in the [Ca(2+)](i) assay were approximately 100-fold lower. Importantly, this shift was also evident in SHSY-5Y cells endogenously expressing hPAC(1)R. Furthermore, [Ala(11,22,28)]VIP and maxadilan were selective hVPAC(1)R and hPAC(1)R agonists, respectively, and although R3P65 had no demonstrable hVPAC(2)R selectivity, these compounds exhibited comparable reductions in [Ca(2+)](i) EC(50) values. In contrast, PG97-269 and PG99-465, putatively selective hVPAC(1)R and hVPAC(2)R antagonists, respectively, were marginally less potent in [cAMP](i) studies, whereas M65 was equipotent at hPAC(1)R. Moreover, PG99-465 alone increased [cAMP](i) at all three hVPAC/PAC receptor subtypes, with full hVPAC(1)R and hPAC(1)R agonism. With equivalent agonist ROPs generated in both assays, [Ca(2+)](i) signalling provides an alternative approach to examine hVPAC/PAC receptor pharmacology. However, these studies underscore the paucity of receptor selective compounds, complexities in comparing drug potencies across assays, and the pleiotropic nature of VPAC/PAC-receptor signalling.

Acquired QT interval prolongation and HERG: implications for drug discovery and development.

Putative interactions between the Human Ether-a-go-go Related Gene (HERG), QT interval prolongation and Torsades de Pointes (TdP) are now integral components of any discussion on drug safety. HERG encodes for the inwardly rectifying potassium channel (I(Kr)), which is essential to the maintenance of normal cardiac function. HERG channel mutations are responsible for one form of familial long QT syndrome, a potentially deadly inherited cardiac disorder associated with TdP. Moreover, drug-induced (acquired) QT interval prolongation has been associated with an increase in the incidence of sudden unexplained deaths, with HERG inhibition implicated as the underlying cause. Subsequently, a number of non-cardiovascular drugs which induce QT interval prolongation and/or TdP have been withdrawn. However, a definitive link between HERG, QT interval prolongation and arrhythmogenesis has not been established. Nevertheless, this area is subject to ever increasing regulatory scrutiny. Here we review the relationship between HERG, long QT syndrome and TdP, together with a summary of the associated regulatory issues, and developments in pre-clinical screening.

Nicotine improves sustained attention in mice: evidence for involvement of the alpha7 nicotinic acetylcholine receptor.

In humans, nicotine has been shown to improve attention in both normal and impaired individuals. Observations in rats reflect some, but not all aspects of the nicotine-induced improvements in humans. To date these findings have not been replicated in mice. To examine the effect of nicotine on sustained attention in mice, we have established a version of the 5-choice serial reaction-time (5-CSR) task with graded levels of difficulty, based upon spatial displacement and a variable intertrial interval. Using this paradigm, microgram doses of nicotine produced a consistent reduction in the level of omissions and an improvement in proportion correct in normal mice. This improvement in sustained attention was made irrespectively of whether mice had previously received nicotine. In an attempt to elucidate which nicotinic acetylcholine receptor (nAChR) subtype(s) mediate this effect, we examined the performance of alpha7 nAChR knockout (KO) mice in the 5-CSR task. alpha7 nAChR KO mice not only acquired the task more slowly than their wild-type littermates, but on attaining asymptotic performance, they exhibited a higher level of omissions. In conclusion, by increasing the level of task difficulty, the performance of mice was maintained at sufficiently low levels to allow a demonstrable improvement in performance upon nicotine administration. Furthermore, as alpha7 KO mice are clearly impaired in the acquisition and asymptotic performance of this task, the alpha7 nAChR may be involved in mediating these effects of nicotine.

Comparison of effects of MgCl2 and Gpp(NH)p on antagonist and agonist radioligand binding to adenosine A1 receptors.

AIM: To investigate modulation of antagonist and agonist binding to adenosine A1 receptors by MgCl2 and 5 -guanylimidodiphosphate (Gpp(NH)p) using rat brain membranes and the A1 antagonist [3H]-8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX) and the A1 agonist [3H]-2-chloro-N6-cyclopentyladenosine ([3H]CCPA). METHODS: Parallel saturation and inhibition studies were performed using well-characterised radioligand binding assays and a Brandel Cell Harvester. RESULTS: MgCl2 produced a concentration-dependent decrease (44%), whereas Gpp(NH)p increased [3H]DPCPX binding (19%). In [3H]DPCPX competition studies, agonist affinity was 1.5-14.6-fold higher and 4.6-10-fold lower in the presence of 10 mmol/L MgCl2 and 10 micromol/L Gpp(NH)p respectively; antagonist affinity was unaffected. The decrease in agonist affinity with increasing Gpp(NH)p concentrations was due to a reduction in the proportion of binding to the high affinity receptor state. In contrast to [3H]DPCPX, MgCl2 produced a concentration-dependent increase (72%) and Gpp(NH)p a decrease (85%) in [3H]CCPA binding. Using [3H]CCPA, agonist affinities were 5-17-fold higher than those for [3H]DPCPX, consistent with binding only to the high affinity receptor state. Agonist affinity was 1.3-10.5-fold higher and 2.4-4.7-fold lower on adding MgCl2 or Gpp(NH)p respectively; antagonist affinities were as for [3H]DPCPX. CONCLUSION: The inconsistencies surrounding the effects of MgCl2 and guanine nucleotides on radioligand binding to adenosine A1 receptors were systematically examined. The effects of MgCl2 and Gpp(NH)p on agonist binding to A1 receptors are consistent with their roles in stimulating GTP-hydrolysis at the G-protein alpha-subunit and in blocking formation of the high affinity agonist-receptor-G protein complex.