SARS-CoV-2 and Epstein-Barr Virus-like Particles Associate and Fuse with Extracellular Vesicles in Virus Neutralization Tests

The successful development of effective viral vaccines depends on well-known correlates of protection, high immunogenicity, acceptable safety criteria, low reactogenicity, and well-designed immune monitoring and serology. Virus-neutralizing antibodies are often a good correlate of protective immunity, and their serum concentration is a key parameter during the pre-clinical and clinical testing of vaccine candidates. Viruses are inherently infectious and potentially harmful, but we and others developed replication-defective SARS-CoV-2 virus-like-particles (VLPs) as surrogates for infection to quantitate neutralizing antibodies with appropriate target cells using a split enzyme-based approach. Here, we show that SARS-CoV-2 and Epstein-Barr virus (EBV)-derived VLPs associate and fuse with extracellular vesicles in a highly specific manner, mediated by the respective viral fusion proteins and their corresponding host receptors. We highlight the capacity of virus-neutralizing antibodies to interfere with this interaction and demonstrate a potent application using this technology. To overcome the common limitations of most virus neutralization tests, we developed a quick in vitro diagnostic assay based on the fusion of SARS-CoV-2 VLPs with susceptible vesicles to quantitate neutralizing antibodies without the need for infectious viruses or living cells. We validated this method by testing a set of COVID-19 patient serum samples, correlated the results with those of a conventional test, and found good sensitivity and specificity. Furthermore, we demonstrate that this serological assay can be adapted to a human herpesvirus, EBV, and possibly other enveloped viruses.

Quantitation of SARS-CoV-2 neutralizing antibodies with a virus-free, authentic test

Neutralizing antibodies (NAbs), and their concentration in sera of convalescents and vaccinees are a correlate of protection from COVID-19. The antibody concentrations in clinical samples that neutralize SARS-CoV-2 are difficult and very cumbersome to assess with conventional virus neutralization tests (cVNTs), which require work with the infectious virus and biosafety level 3 containment precautions. Alternative virus neutralization tests currently in use are mostly surrogate tests based on direct or competitive enzyme immunoassays or use viral vectors with the spike protein as the single structural component of SARS-CoV-2. To overcome these obstacles, we developed a virus-free, safe and very fast (4.5 h) in vitro diagnostic test based on engineered yet authentic SARS-CoV-2 virus-like-particles (VLPs). They share all features of the original SARS-CoV-2 but lack the viral RNA genome and thus are non-infectious. NAbs induced by infection or vaccination, but also potentially neutralizing monoclonal antibodies can be reliably quantified and assessed with ease and within hours with our test, because they interfere and block the ACE2-mediated uptake of VLPs by recipient cells. Results from the VLP neutralization test (VLPNT) showed excellent specificity and sensitivity and correlated very well with a cVNT using fully infectious SARS-CoV-2. The results also demonstrated the reduced neutralizing capacity of COVID-19 vaccinee sera against variants of concern of SARS-CoV-2 including omicron B.1.1.529, BA.1.

Impact of the gut microbiome on the atorvastatin-dependent modulation of the serum lipidome

Background and aims

The modulation of serum lipids, in particular of the low-density lipoprotein cholesterol (LDL-C), by statins varies between individuals. The mechanisms regulating this interindividual variation are only poorly understood. Here, we investigated the relation between the gut microbiome and the regulatory properties of atorvastatin on the serum lipidome using mice with depleted gut microbiome.

Methods

Over a period of 6 weeks, mice (C57BL/6) with either an intact (conventional mice, CONV, n=24) or antibiotic-based depleted gut microbiome (antibiotic treated mice, ABS, n=16) were put on standard chow diet (SCD) or high fat diet (HFD), respectively. During the last 4 weeks of treatment atorvastatin (Ator, 10mg/kg body weight/day) or control vehicle was administered via daily oral gavage. Blood lipids (total cholesterol, VLDL, LDL-C, HDL-C) and serum sphingolipids were compared among the groups. The expressions of hepatic and intestinal genes involved in cholesterol metabolism were analyzed by qRT-PCR. Alterations in the gut microbiota profile of mice with intact gut microbiome were examined using 16S RNA qRT-PCR.

Results

In CONV mice, HFD led to significantly increased blood LDL-C levels as compared with SCD (HFD: 36.8±1.4 mg/dl vs. SCD: 22.0±1.8 mg/dl; P<0.01). In CONV mice atorvastatin treatment significantly reduced blood LDL-C levels after HFD, whereas in ABS mice the LDL-C lowering effect of atorvastatin was markedly attenuated (CONV+HFD+Ator: 31.0±1.8 mg/dl vs. ABS+HFD+Ator: 46.4±3 mg/dl; P<0.01). A significant reduction in the abundance of several plasma lipids, in particular sphingolipids and glycerophospholipids upon atorvastatin treatment was observed in CONV mice, but not in ABS mice. The expressions of distinct hepatic and intestinal cholesterol-regulating genes (ldlr, srebp2, pcsk9 and npc1l1) upon atorvastatin treatment were significantly altered in gut microbiota depleted mice. In response to HFD a decrease in the relative abundance of the bacterial phyla Bacteroides and an increase in the relative abundance of Firmicutes was observed. The altered ratio between Bacteroides and Firmicutes in HFD fed mice was partly reversed upon atorvastatin treatment.

Conclusions

Our findings indicate a crucial role of the gut microbiome for the regulatory properties of atorvastatin on the serum lipidome and, in turn, support a critical impact of atorvastatin on the gut microbial composition. The results provide novel insights into potential microbiota related mechanisms underlying interindividual variation in modulation of the serum lipidome by statins, given interindividual differences in microbiome composition and function.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): German Heart Research Foundation

54Role of the gut microbiome for the cholesterol lowering effect of atorvastatin

Background and aims

Statins show interindividual differences in the extent of low-density lipoprotein cholesterol (LDL-C) reduction. The mechanisms of this interindividual variation are not fully understood. Here, we examined the potential role of the gut microbiome for the LDL-C lowering property of atorvastatin.

Methods

Mice (C57BL/6) with either intact (conventional mice, CONV, n=24) or with antiobiotic depleted gut microbiome (gnotobiotic, n=16), were put on standard chow diet (SCD) (n=11) or high fat diet (HFD) (n=29) for 6 weeks. During the last 4 weeks atorvastatin (Ator, 10mg/kg body weight/day) or control vehicle was orally applied via gavage. Blood levels of LDL-C and glucose and body weight after 6 weeks of treatment were compared between the groups. Expression of genes involved in hepatic and intestinal cholesterol-metabolism were examined. Faeces of CONV mice were analyzed for alteration of the gut microbiota profile upon atorvastatin treatment using 16S rRNA qPCR.

Results

HFD fed mice with intact gut microbiome showed significantly increased blood LDL-C levels as compared to SCD (HFD: 36.8±1.4 mg/dl vs. SCD: 22.0±1.8 mg/dl; P<0.01). Bodyweight gain or blood glucose levels after HFD were not significantly different between CONV and gnotobiotic mice. While in CONV mice atorvastatin significantly reduced LDL-C levels after HFD, in gnotobiotic mice the LDL-C lowering effect of atorvastatin was attenuated (CONV+HFD+Ator: 31.0±1.8 mg/dl vs. gnotobiotic mice+HFD+Ator: 46.4±3 mg/dl; P<0.01). The expression of genes involved in hepatic cholesterol synthesis was not significantly altered in gnotobiotic mice as compared to CONV mice. In CONV mice HFD decreased the relative abundance of the bacterial phyla Bacteroidetes and increased the abundance of Firmicutes as compared to SCD. The ratio between Firmicutes to Bacteroidetes was shifted towards control conditions upon atorvastatin treatment.

Conclusions

The results of this study suggest a regulatory impact of atorvastatin on the gut-microbial profile and, in turn, a crucial role of the gut-microbiome for the LDL-C lowering effect of atorvastatin independent of its regulation of hepatic cholesterol synthesis. Our findings provide novel insight into potential microbiota-related mechanisms causing interindividual variation in LDL-C lowering effects of statins.

Acknowledgement/Funding

German Heart Research Foundation

The practical other: teleology and its development

We argue for teleology as a description of the way in which we ordinarily understand others' intentional actions. Teleology starts from the close resemblance between the reasoning involved in understanding others' actions and one's own practical reasoning involved in deciding what to do. We carve out teleology's distinctive features more sharply by comparing it to its three main competitors: theory theory, simulation theory, and rationality theory. The plausibility of teleology as our way of understanding others is underlined by developmental data in its favour.

Pro-social cognition: helping, practical reasons, and 'theory of mind'

There is converging evidence that over the course of the second year children become good at various fairly sophisticated forms of pro-social activities, such as helping, informing and comforting. Not only are toddlers able to do these things, they appear to do them routinely and almost reliably. A striking feature of these interventions, emphasized in the recent literature, is that they show precocious abilities in two different domains: they reflect complex 'theory of mind' abilities as well as 'altruistic motivation'. Our aim in this paper is to present a theoretical hypothesis that bears on both kinds of developments. The suggestion is that children's 'instrumental helping' reflects their budding understanding of practical reasons (in the standard sense of 'considerations that count in favour of' someone's acting in a certain way). We can put the basic idea in the familiar terminology of common coding: toddlers conceive of the goals of others' actions in the same format as the goals of their own actions: in terms of features of their situation that provide us with reasons to act.

Ovarian cancer stem cells

Because of its semi-solid character in dissemination and growth, advanced ovarian cancer with its hundreds of peritoneal tumor nodules and plaques appears to be an excellent in vivo model for studying the cancer stem cell hypothesis. The most important obstacle, however, is to adequately define and isolate these tumor-initiating cells endowed with the properties of anoikis-resistance and unlimited self-renewal. Until now, no universal single marker or marker constellation has been found to faithfully isolate (ovarian) cancer stem cells. As these multipotent cells are known to possess highly elaborated efflux systems for cytotoxic agents, these pump systems have been exploited to outline putative stem cells as a side-population (SP) via dye exclusion analysis. Furthermore, the cells in question have been isolated via flow cytometry on the basis of cell surface markers thought to be characteristic for stem cells.In the Vienna variant of the ovarian cancer cell line A2780 a proof-of-principle model with both a stable SP and a stable ALDH1A1+ cell population was established. Double staining clearly revealed that both cell fractions were not identical. Of note, A2780V cells were negative for expression of surface markers CD44 and CD117 (c-kit). When cultured on monolayers of healthy human mesothelial cells, green-fluorescence-protein (GFP)-transfected SP of A2780V exhibited spheroid-formation, whereas non-side-population (NSP) developed a spare monolayer growing over the healthy mesothelium. Furthermore, A2780V SP was found to be partially resistant to platinum. However, this resistance could not be explained by over-expression of the "excision repair cross-complementation group 1" (ERCC1) gene, which is essentially involved in the repair of platinated DNA damage. ERCC1 was, nonetheless, over-expressed in A2780V cells grown as spheres under stem cell-selective conditions as compared to adherent monolayers cultured under differentiating conditions. The same was true for the primary ovarian cancer cells B-57.In summary our investigations indicate that even in multi-passaged cancer cell lines hierarchic government of growth and differentiation is conserved and that the key cancer stem cell population may be composed of small overlapping cell fractions defined by various arbitrary markers.

From infants' to children's appreciation of belief

Evidence is accumulating that infants are sensitive to people's false beliefs, whereas children pass the standard false belief test at around 4 years of age. Debate currently centres on the nature of early and late understanding. We defend the view that early sensitivity to false beliefs shown in 'online tasks' (where engagement with ongoing events reflects an expectation of what will happen without a judgement that it will happen) reflects implicit/unconscious social knowledge of lawful regularities. The traditional false belief task requires explicit consideration of the agent's subjective perspective on his reasons for action. This requires an intentional switch of perspectives not possible before 4 years of age as evidenced by correlations between the false belief task and many different perspective-taking tasks.

False-positive radio-iodinated metaiodobenzylguanidine (123I-MIBG) accumulation in a mast cell-infiltrated infantile haemangioma

Radio-iodinated metaiodobenzylguanidine ((123)I-MIBG) is used for the detection and staging of neuroblastoma, pheochromcytoma and other neuroendocrine tumours in diagnostic nuclear medicine. A specific uptake and storage mechanism provides the basis for imaging with (123)I-MIBG. Nevertheless, cases of false-positive (123)I-MIBG scintigraphy with accumulation in non-chromaffin tumours have been described. Here, we present a case of a false-positive (123)I-MIBG scan in a case of a mast-cell infiltrated infantile haemangioma and discuss the possible uptake mechanism.

Intracoronary photodynamic therapy reduces neointimal growth without suppressing re-endothelialisation in a porcine model

OBJECTIVE

To examine the effects of intracoronary PhotoPoint photodynamic therapy (PDT) with a new photosensitiser, MV0611, in the overstretch balloon and stent porcine models of restenosis.

METHODS

28 pigs were injected with 3 mg/kg of MV0611 systemically 4 h before the procedure. Animals were divided into either the balloon overstretch injury (BI) group (n = 19) or the stented group (n = 9). After BI, a centred delivery catheter was positioned in the artery to cover the injured area, and light (532 nm, 125 J/cm(2)) was applied to activate the drug (n = 10). Control arteries (n = 9) were not activated by light. In the stented group, the drug was light activated before stent deployment. Serial sections of vessels were processed 14 days after treatment in the BI group and 30 days after treatment in the stented group for histomorphometric or immunohistochemical analysis.

RESULTS

Intracoronary PDT significantly reduced intimal thickness in both BI and stented arteries (about 65%: 0.22 (SEM 0.05) mm v 0.62 (0.05) mm, p < 0.01; and about 26%: 0.40 (0.04) mm v 0.54 (0.04) mm, p < 0.01, respectively). PDT increased luminal area by

CONCLUSION

Intracoronary PhotoPoint PDT with MV0611 reduces intimal proliferation without suppressing re-endothelialisation in a porcine model of restenosis.

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MESH Headings

• Angioplasty, Balloon
• Animals
• Cell Proliferation
• Coronary Restenosis/prevention & control
• Coronary Vessels/injuries
• Feasibility Studies
• Female
• Immunohistochemistry
• Male
• Mesoporphyrins/pharmacokinetics
• Mesoporphyrins/therapeutic use
• Photochemotherapy/methods
• Photosensitizing Agents/pharmacokinetics
• Photosensitizing Agents/therapeutic use
• Random Allocation
• Stents
• Swine
• Tunica Intima

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Affiliation(s)

R Waksman Division of Cardiology, Washington Hospital Center, Washington, DC, USA.
I M Leitch
J Roessler
H Yazdi
R Seabron
F Tio
R W Scott
R I Grove
S Rychnovsky
B Robinson
R Pakala
E Cheneau

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