A New Methodology for the Oxygen Measurement in Lung Tissue of an Aged Ferret Model Proves Hypoxia During COVID-19

Oxygen as a key element has a high impact on cellular processes. Infection with a pathogen such as SARS-CoV-2 and following inflammation may lead to hypoxic conditions in tissue that impact cellular responses. To develop optimized translational in vitro models for a better understanding of physiologic and pathophysiologic oxygen conditions, it is a prerequisite to determine oxygen levels generated in vivo. Our study objective was the establishment of an invasive method for oxygen measurements using a luminescence-based microsensor to determine the dissolved oxygen in the lung tissue of ferrets as animal models for SARS-CoV-2 research. In analogy to humans, aged ferrets are more likely to show clinical signs after SARS-CoV-2 infection compared to young animals. To investigate oxygen levels during a respiratory viral infection, we intratracheally infected nine aged (3-year-old) ferrets with SARS-CoV-2. The aged SARS-CoV-2 infected ferrets showed mild to moderate clinical signs associated with prolonged viral RNA shedding until 14 days post infection (dpi). SARS-CoV-2 infected ferrets showed histopathologic lung lesion scores that significantly negatively correlated with oxygen levels in lung tissue. At 4 dpi, oxygen levels in lung tissue were significantly lower (mean %O2 of 3.89 ≙ ≈ 27.78 mmHg) compared to the negative control group (mean %O2 of 8.65 ≙ ≈ 61.4 mmHg). In summary, we succeeded in determining the pathophysiologic oxygen conditions in the lung tissue of aged SARS-CoV-2-infected ferrets. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/). .

SARS-CoV-2 inactivation in laboratory animal tissues with 4% formaldehyde or 5% glutaraldehyde for transfer to biosafety level 1 laboratories

The SARS-CoV-2 pandemic required the immediate need to transfer inactivated tissue from biosafety level (BSL)-3 to BSL-1 areas to enable downstream analytical methods. No validated SARS-CoV-2 inactivation protocols were available for either formaldehyde (FA)-fixed or glutaraldehyde (GA)-fixed tissues. Therefore, representative tissue from ferrets and hamsters was spiked with 2.2 × 106 tissue culture infectious dose 50% per ml (TCID50/ml) SARS-CoV-2 or were obtained from mice experimentally infected with SARS-CoV-2. SARS-CoV-2 inactivation was demonstrated with 4% FA or 5% GA at room temperature for 72 hours by a titer reduction of up to 103.8 TCID50/ml in different animal tissues with a maximum protein content of 100 µg/mg and a thickness of up to 10 mm for FA and 8 mm for GA. Our protocols can be easily adapted for validating the inactivation of other pathogens to allow for the transfer of biological samples from BSL-3 areas to BSL-1 laboratories.

Nanobodies to multiple spike variants and inhalation of nanobody-containing aerosols neutralize SARS-CoV-2 in cell culture and hamsters

The ongoing threat of COVID-19 has highlighted the need for effective prophylaxis and convenient therapies, especially for outpatient settings. We have previously developed highly potent single-domain (VHH) antibodies, also known as nanobodies, that target the Receptor Binding Domain (RBD) of the SARS-CoV-2 Spike protein and neutralize the Wuhan strain of the virus. In this study, we present a new generation of anti-RBD nanobodies with superior properties. The primary representative of this group, Re32D03, neutralizes Alpha to Delta as well as Omicron BA.2.75; other members neutralize, in addition, Omicron BA.1, BA.2, BA.4/5, and XBB.1. Crystal structures of RBD-nanobody complexes reveal how ACE2-binding is blocked and also explain the nanobodies' tolerance to immune escape mutations. Through the cryo-EM structure of the Ma16B06-BA.1 Spike complex, we demonstrated how a single nanobody molecule can neutralize a trimeric spike. We also describe a method for large-scale production of these nanobodies in Pichia pastoris, and for formulating them into aerosols. Exposing hamsters to these aerosols, before or even 24 h after infection with SARS-CoV-2, significantly reduced virus load, weight loss and pathogenicity. These results show the potential of aerosolized nanobodies for prophylaxis and therapy of coronavirus infections.

Characterization of young and aged ferrets as animal models for SARS-CoV-2 infection with focus on neutrophil extracellular traps

Neutrophil extracellular traps (NETs) are net-like structures released by activated neutrophils upon infection [e.g., severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)] as part of the innate immune response that have protective effects by pathogen entrapment and immobilization or result in detrimental consequences for the host due to the massive release of NETs and their impaired degradation by nucleases like DNase-1. Higher amounts of NETs are associated with coronavirus disease 2019 (COVID-19) severity and are a risk factor for severe disease outcome. The objective of our study was to investigate NET formation in young versus aged ferrets to evaluate their value as translational model for SARS-CoV-2-infection and to correlate different NET markers and virological parameters. In each of the two groups (young and aged), nine female ferrets were intratracheally infected with 1 mL of 106 TCID50/mL SARS-CoV-2 (BavPat1/2020) and euthanized at 4, 7, or 21 days post-infection. Three animals per group served as negative controls. Significantly more infectious virus and viral RNA was found in the upper respiratory tract of aged ferrets. Interestingly, cell-free DNA and DNase-1 activity was generally higher in bronchoalveolar lavage fluid (BALF) but significantly lower in serum of aged compared to young ferrets. In accordance with these data, immunofluorescence microscopy revealed significantly more NETs in lungs of aged compared to young infected ferrets. The association of SARS-CoV-2-antigen in the respiratory mucosa and NET markers in the nasal conchae, but the absence of virus antigen in the lungs, confirms the nasal epithelium as the major location for virus replication as described for young ferrets. Furthermore, a strong positive correlation was found between virus shedding and cell-free DNA or the level of DNAse-1 activity in aged ferrets. Despite the increased NET formation in infected lungs of aged ferrets, the animals did not show a strong NET phenotype and correlation among tested NET markers. Therefore, ferrets are of limited use to study SARS-CoV-2 pathogenesis associated with NET formation. Nevertheless, the mild to moderate clinical signs, virus shedding pattern, and the lung pathology of aged ferrets confirm those animals as a relevant model to study age-dependent COVID-19 pathogenesis.

CYP19A1 mediates severe SARS-CoV-2 disease outcome in males

Male sex represents one of the major risk factors for severe COVID-19 outcome. However, underlying mechanisms that mediate sex-dependent disease outcome are as yet unknown. Here, we identify the CYP19A1 gene encoding for the testosterone-to-estradiol metabolizing enzyme CYP19A1 (also known as aromatase) as a host factor that contributes to worsened disease outcome in SARS-CoV-2-infected males. We analyzed exome sequencing data obtained from a human COVID-19 cohort (n = 2,866) using a machine-learning approach and identify a CYP19A1-activity-increasing mutation to be associated with the development of severe disease in men but not women. We further analyzed human autopsy-derived lungs (n = 86) and detect increased pulmonary CYP19A1 expression at the time point of death in men compared with women. In the golden hamster model, we show that SARS-CoV-2 infection causes increased CYP19A1 expression in the lung that is associated with dysregulated plasma sex hormone levels and reduced long-term pulmonary function in males but not females. Treatment of SARS-CoV-2-infected hamsters with a clinically approved CYP19A1 inhibitor (letrozole) improves impaired lung function and supports recovery of imbalanced sex hormones specifically in males. Our study identifies CYP19A1 as a contributor to sex-specific SARS-CoV-2 disease outcome in males. Furthermore, inhibition of CYP19A1 by the clinically approved drug letrozole may furnish a new therapeutic strategy for individualized patient management and treatment.

Water-film thickness imaging based on time-multiplexed near-infrared absorption with up to 500 Hz repetition rate

We demonstrate high-repetition-rate imaging of the liquid-film thickness in the 50-1000 µm range resulting from impinging water droplets on a glass surface. The pixel-by-pixel ratio of line-of-sight absorption at two time-multiplexed near-infrared wavelengths at 1440 and 1353 nm was detected with a high-frame-rate InGaAs focal-plane array camera. Frame rates of 1 kHz and thus measurement rates of 500 Hz could be achieved, well suited to capture the fast dynamics of droplet impingement and film formation. The droplets were sprayed onto the glass surface using an atomizer. Suitable absorption wavelength bands for water droplet/film imaging were determined from Fourier-transform infrared (FTIR) spectra of pure water between 298 and 338 K. At 1440 nm, the water absorption is nearly temperature-independent, making the measurements robust against temperature fluctuations. Time-resolved imaging measurements capturing the dynamics of the water droplet impingement and evolution were successfully demonstrated.

β-Propiolactone (BPL)-inactivation of SARS-Co-V-2: in vitro validation with focus on saliva from COVID-19 patients for scent dog training

β-Propiolactone (BPL) is an organic compound widely used as an inactivating agent in vaccine development and production, for example for SARS-CoV, SARS-CoV-2 and Influenza viruses. Inactivation of pathogens by BPL is based on an irreversible alkylation of nucleic acids but also on acetylation and cross-linking between proteins, DNA or RNA. However, the protocols for BPL inactivation of viruses vary widely. Handling of infectious, enriched SARS-CoV-2 specimens and diagnostic samples from COVID-19 patients is recommended in biosafety level (BSL)-3 or BSL-2 laboratories, respectively. We validated BPL inactivation of SARS-CoV-2 in saliva samples with the objective to use saliva from COVID-19 patients for training of scent dogs for the detection of SARS-CoV-2 positive individuals. Therefore, saliva samples and cell culture medium buffered with NaHCO₃ (pH 8.3) were comparatively spiked with SARS-CoV-2 and inactivated with 0.1% BPL for 1hour (h) or 71h (± 1h) at 2-8°C, followed by hydrolysis of BPL at 37°C for 1 or 2h, converting BPL into non-toxic beta-hydroxy-propionic acid. SARS-CoV-2 inactivation was demonstrated by a titre reduction of up to 10^4 TCID₅₀/ml in the spiked samples for both inactivation periods using virus titration and virus isolation, respectively. The validated method was confirmed by successful inactivation of pathogens in saliva samples from COVID-19 patients. Furthermore, we reviewed the currently available literature on SARS-CoV-2 inactivation by BPL. Accordingly, BPL-inactivated, hydrolysed samples can be handled in a non-laboratory setting. Furthermore, our BPL inactivation protocols can be adapted to validation experiments with other pathogens.

Canine real-time detection of SARS-CoV-2 infections in the context of a mass screening event

Introduction

Previous research demonstrated that medical scent detection dogs have the ability to distinguish SARS-CoV-2 positive from negative samples with high diagnostic accuracy. To deploy these dogs as a reliable screening method, it is mandatory to examine if canines maintain their high diagnostic accuracy in real-life screening settings. We conducted a study to evaluate the performance of medical scent detection dogs under real-life circumstances.

Methods

Eight dogs were trained to detect SARS-CoV-2 RT-qPCR-positive samples. Four concerts with a total of 2802 participants were held to evaluate canines’ performance in screening individuals for SARS-CoV-2 infection. Sweat samples were taken from all participants and presented in a line-up setting. In addition, every participant had been tested with a SARS-CoV-2 specific rapid antigen test and a RT-qPCR and they provided information regarding age, sex, vaccination status and medical disease history. The participants’ infection status was unknown at the time of canine testing. Safety measures such as mask wearing and distance keeping were ensured.

Results

The SARS-CoV-2 detection dogs achieved a diagnostic specificity of 99.93% (95% CI 99.74% to 99.99%) and a sensitivity of 81.58% (95% CI 66.58% to 90.78%), respectively. The overall rate of concordant results was 99.68%. The majority of the study population was vaccinated with varying vaccines and vaccination schemes, while several participants had chronic diseases and were under chronic medication. This did not influence dogs’ decisions.

Conclusion

Our results demonstrate that SARS-CoV-2 scent detection dogs achieved high diagnostic accuracy in a real-life scenario. The vaccination status, previous SARS-CoV-2 infection, chronic disease and medication of the participants did not influence the performance of the dogs in detecting the acute infection. This indicates that dogs provide a fast and reliable screening option for public events in which high-throughput screening is required.

Reversible Glutamate Coordination to High-Valent Nickel Protects the Active Site of a [NiFe] Hydrogenase from Oxygen

NAD⁺-reducing [NiFe] hydrogenases are valuable biocatalysts for H₂-based energy conversion and the regeneration of nucleotide cofactors. While most hydrogenases are sensitive toward O₂ and elevated temperatures, the soluble NAD⁺-reducing [NiFe] hydrogenase from Hydrogenophilus thermoluteolus (HtSH) is O₂-tolerant and thermostable. Thus, it represents a promising candidate for biotechnological applications. Here, we have investigated the catalytic activity and active-site structure of native HtSH and variants in which a glutamate residue in the active-site cavity was replaced by glutamine, alanine, and aspartate. Our biochemical, spectroscopic, and theoretical studies reveal that at least two active-site states of oxidized HtSH feature an unusual architecture in which the glutamate acts as a terminal ligand of the active-site nickel. This observation demonstrates that crystallographically observed glutamate coordination represents a native feature of the enzyme. One of these states is diamagnetic and characterized by a very high stretching frequency of an iron-bound active-site CO ligand. Supported by density-functional-theory calculations, we identify this state as a high-valent species with a biologically unprecedented formal Ni(IV) ground state. Detailed insights into its structure and dynamics were obtained by ultrafast and two-dimensional infrared spectroscopy, demonstrating that it represents a conformationally strained state with unusual bond properties. Our data further show that this state is selectively and reversibly formed under oxic conditions, especially upon rapid exposure to high O₂ levels. We conclude that the kinetically controlled formation of this six-coordinate high-valent state represents a specific and precisely orchestrated stereoelectronic response toward O₂ that could protect the enzyme from oxidative damage.

Implementing Remote Collaboration in a Virtual Patient Platform: Usability Study

BACKGROUND

Learning with virtual patients is highly popular for fostering clinical reasoning in medical education. However, little learning with virtual patients is done collaboratively, despite the potential learning benefits of collaborative versus individual learning.

OBJECTIVE

This paper describes the implementation of student collaboration in a virtual patient platform. Our aim was to allow pairs of students to communicate remotely with each other during virtual patient learning sessions. We hypothesized that we could provide a collaborative tool that did not impair the usability of the system compared to individual learning and that this would lead to better diagnostic accuracy for the pairs of students.

METHODS

Implementing the collaboration tool had five steps: (1) searching for a suitable software library, (2) implementing the application programming interface, (3) performing technical adaptations to ensure high-quality connections for the users, (4) designing and developing the user interface, and (5) testing the usability of the tool in 270 virtual patient sessions. We compared dyad to individual diagnostic accuracy and usability with the 10-item System Usability Scale.

RESULTS

We recruited 137 students who worked on 6 virtual patients. Out of 270 virtual patient sessions per group (45 dyads times 6 virtual patients, and 47 students working individually times 6 virtual patients minus 2 randomly selected deleted sessions) the students made successful diagnoses in 143/270 sessions (53%, SD 26%) when working alone and 192/270 sessions (71%, SD 20%) when collaborating (P=.04, η²=0.12). A usability questionnaire given to the students who used the collaboration tool showed a usability score of 82.16 (SD 1.31), representing a B+ grade.

CONCLUSIONS

The collaboration tool provides a generic approach for collaboration that can be used with most virtual patient systems. The collaboration tool helped students diagnose virtual patients and had good overall usability. More broadly, the collaboration tool will provide an array of new possibilities for researchers and medical educators alike to design courses for collaborative learning with virtual patients.

Ferrets are valuable models for SARS-CoV-2 research

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), resulted in an ongoing pandemic with millions of deaths worldwide. Infection of humans can be asymptomatic or result in fever, fatigue, dry cough, dyspnea, and acute respiratory distress syndrome with multiorgan failure in severe cases. The pathogenesis of COVID-19 is not fully understood, and various models employing different species are currently applied. Ferrets can be infected with SARS-CoV-2 and efficiently transmit the virus to contact animals. In contrast to hamsters, ferrets usually show mild disease and viral replication restricted to the upper airways. Most reports have used the intranasal inoculation route, while the intratracheal infection model is not well characterized. Herein, we present clinical, virological, and pathological data from young ferrets intratracheally inoculated with SARS-CoV-2. Infected animals showed no significant clinical signs, and had transient infection with peak viral RNA loads at 4 days postinfection, mild to moderate rhinitis, and pulmonary endothelialitis/vasculitis. Viral antigen was exclusively found in the respiratory epithelium of the nasal cavity, indicating a particular tropism for cells in this location. Viral antigen was associated with epithelial damage and influx of inflammatory cells, including activated neutrophils releasing neutrophil extracellular traps. Scanning electron microscopy of the nasal respiratory mucosa revealed loss of cilia, shedding, and rupture of epithelial cells. The currently established ferret SARS-CoV-2 infection models are comparatively discussed with SARS-CoV-2 pathogenesis in mink, and the advantages and disadvantages of both species as research models for zoonotic betacoronaviruses are highlighted.

Detection of Post-COVID-19 Patients Using Medical Scent Detection Dogs—A Pilot Study

There is a growing number of COVID-19 patients experiencing long-term symptoms months after their acute SARS-CoV-2 infection. Previous research proved dogs' ability to detect acute SARS-CoV-2 infections, but has not yet shown if dogs also indicate samples of patients with post-COVID-19 condition (Long COVID). Nine dogs, previously trained to detect samples of acute COVID-19 patients, were confronted with samples of Long COVID patients in two testing scenarios. In test scenario I (samples of acute COVID-19 vs. Long COVID) dogs achieved a mean sensitivity (for acute COVID-19) of 86.7% (95%CI: 75.4–98.0%) and a specificity of 95.8% (95%CI: 92.5–99.0%). When dogs were confronted with Long COVID and negative control samples in scenario IIa, dogs achieved a mean sensitivity (for Long COVID) of 94.4 (95%CI: 70.5–100.0%) and a specificity of 96.1% (95%CI: 87.6–100.0%). In comparison, when acute SARS-CoV-2 positive samples and negative control samples were comparatively presented (scenario IIb), a mean sensitivity of 86.9 (95%CI: 55.7–100.0%) and a specificity of 88.1% (95%CI: 82.7–93.6%) was attained. This pilot study supports the hypothesis of volatile organic compounds (VOCs) being long-term present after the initial infection in post-COVID-19 patients. Detection dogs, trained with samples of acute COVID-19 patients, also identified samples of Long COVID patients with a high sensitivity when presented next to samples of healthy individuals. This data may be used for further studies evaluating the pathophysiology underlying Long COVID and the composition of specific VOC-patterns released by SARS-CoV-2 infected patients throughout the course of this complex disease.

Modification of Skin Flaps for Single-Stage Reconstruction of the Nasal Ala Using All-Layer Suture-A Prospective Study

BACKGROUND AND OBJECTIVES

After local flaps, it may be necessary to reconstruct the contour of the nasal ala. This is possible with a single-stage all-layer shaping suture. In the present study, the functional and aesthetic results after single-stage reconstruction of the nasal ala were prospectively evaluated.

PATIENTS AND METHODS

Patients who underwent surgery for skin tumors of the nose between 06/2019 and 06/2020 who required reconstruction of the nasal ala as part of the defect closure and had an all-layer suture used were prospectively included in the study. A standardized evaluation of aesthetic and functional outcome was conducted by the patient and a physician at discharge as well as 4 weeks later. Patients additionally underwent a follow-up survey 6 months later.

RESULTS

Thirty-seven patients were included in the study. Four weeks postoperatively, all flaps were found to be fully healed and vital. Aesthetic outcome at 4 weeks was rated as very good or good by physicians in 73% and by patients in 78.4%. Persistent complications due to reduced blood flow were not observed.

CONCLUSION

The reshaping of the nasal ala as part of the defect reconstruction with an all-layer suture demonstrates very good aesthetic as well as functional results and can be performed in a single-stage procedure. .

Regulation of APD and force by Na+/Ca2+ exchanger in hiPSC-cardiomyocytes

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): BMBF

Introduction

Human induced pluripotent stem cell-derived cardiomyocytes (HiPSC-CM) are an emerging, powerful tool to study human cardiac physiology, pharmacology and toxicology, to model cardiovascular diseases or even to use for cardiac repair. Understanding the similarities and differences between hiPSC-CM and adult human cardiomyocytes is critical for their use. Here we focus on sodium calcium exchanger (NCX) who plays a crucial role in the Ca2+-homeostasis in the mammalian heart. Importantly, alterations in NCX expression in human heart are associated with various cardiac pathologies such as heart failure or arrhythmias. In order to investigate whether hiPSC-CM could serve as model for adult human heart NCX we measured the properties of NCX in hiPSC-CM and human ventricular tissue. Rat ventricular tissue was used for comparison.

Methods

HiPSC-CM were differentiated from a healthy iPSC line and dissociated from engineered heart tissue (EHT). Adult human and rat cardiomyocytes were digested from ventricular samples. We measured NCX current by the whole-cell patch clamp technique at 37 °C. Standard sharp microelectrodes were used to record action potentials (AP). Contractile force in human and rat ventricular samples was measured isometrically. A video-optical contractility test system was used to measure force in EHT. SEA0400 (10 µM) was used to block NCX.

Results

NCX currents could be measured in every hiPSC-CM. The NCX current densities in hiPSC-CM were larger than in human ventricular cardiomyocytes (3.2±0.2 pA/pF n=28 vs. 1.3±0.2 pA/pF n=15, p<0.05), but lower than reported for rat left ventricular cardiomyocytes using the same protocol. SEA0400 shortened APD90 markedly in EHT (264.1±24.9 ms to 191±31.6 ms, n=4) and to a lesser extent in rat ventricular tissue (54.4±3.9 ms to 48.9±4.2 ms, n=7). Shortening in human left ventricular preparations was tiny (320±22.1 ms to 305.5±20.3 ms, n=6) and not different from time-matched controls (TMC). Resting membrane potential, action potential amplitude and upstroke velocity were not affected neither in EHT nor in left ventricular preparations (rat and human). Force was significantly increased by NCX block in rat ventricle (by 31±5.4%, n=18) and EHT (by 20.8±3.9%, n=4), but in human left ventricular preparations there was only a tendency to attenuate spontaneous run-down (-3.7±4.3% n=8 with SEA vs. -6.2±3.7% n=12 in TMC).

Conclusion

HiPSC-CM possess NCX in the physiological range. HiPSC-CM show NCX-effects on APD and force as predicted from rat ventricle and in full accordance with cardiac physiology. Lack of NCX effect in human adult ventricles that had been already reported previously needs further investigations.

Outcomes and costs of ureteroscopy, extracorporeal shockwave lithotripsy, and percutaneous nephrolithotomy for the treatment of urolithiasis: an analysis based on health insurance claims data in Germany

Purpose

Comparisons of ureteroscopy (URS), extracorporeal shockwave lithotripsy (SWL), and percutaneous nephrolithotomy (PCNL) for urolithiasis considering long-term health and economic outcomes based on claims data are rare. Our aim was to analyze URS, SWL, and PCNL regarding complications within 30 days, re-intervention, healthcare costs, and sick leave days within 12 months, and to investigate inpatient and outpatient SWL treatment as the latter was introduced in Germany in 2011.

Methods

This retrospective cohort study based on German health insurance claims data included 164,203 urolithiasis cases in 2008–2016. We investigated the number of complications within 30 days, as well as time to re-intervention, number of sick leave days and hospital and ambulatory health care costs within a 12-month follow-up period. We applied negative binomial, Cox proportional hazard, gamma and two-part models and adjusted for patient variables.

Results

Compared to URS cases, SWL and PCNL had fewer 30-day complications, time to re-intervention within 12 months was decreased for SWL and PCNL, SWL and PCNL were correlated with a higher number of sick leave days, and SWL and particularly PCNL were associated with higher costs. SWL outpatients had fewer complications, re-interventions and lower costs than inpatients. This study was limited by the available information in claims data.

Conclusion

URS cases showed benefits in terms of fewer re-interventions, fewer sick leave days, and lower healthcare costs. Only regarding complications, SWL was superior. This emphasizes URS as the most frequent treatment choice. Furthermore, SWL outpatients showed less costs, fewer complications, and re-interventions than inpatients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-021-03903-2.

Discrimination of SARS-CoV-2 Infections From Other Viral Respiratory Infections by Scent Detection Dogs

Background: Testing of possibly infected individuals remains cornerstone of containing the spread of SARS-CoV-2. Detection dogs could contribute to mass screening. Previous research demonstrated canines' ability to detect SARS-CoV-2-infections but has not investigated if dogs can differentiate between COVID-19 and other virus infections. Methods: Twelve dogs were trained to detect SARS-CoV-2 positive samples. Three test scenarios were performed to evaluate their ability to discriminate SARS-CoV-2-infections from viral infections of a different aetiology. Naso- and oropharyngeal swab samples from individuals and samples from cell culture both infected with one of 15 viruses that may cause COVID-19-like symptoms were presented as distractors in a randomised, double-blind study. Dogs were either trained with SARS-CoV-2 positive saliva samples (test scenario I and II) or with supernatant from cell cultures (test scenario III). Results: When using swab samples from individuals infected with viruses other than SARS-CoV-2 as distractors (test scenario I), dogs detected swab samples from SARS-CoV-2-infected individuals with a mean diagnostic sensitivity of 73.8% (95% CI: 66.0-81.7%) and a specificity of 95.1% (95% CI: 92.6-97.7%). In test scenario II and III cell culture supernatant from cells infected with SARS-CoV-2, cells infected with other coronaviruses and non-infected cells were presented. Dogs achieved mean diagnostic sensitivities of 61.2% (95% CI: 50.7-71.6%, test scenario II) and 75.8% (95% CI: 53.0-98.5%, test scenario III), respectively. The diagnostic specificities were 90.9% (95% CI: 87.3-94.6%, test scenario II) and 90.2% (95% CI: 81.1-99.4%, test scenario III), respectively. Conclusion: In all three test scenarios the mean specificities were above 90% which indicates that dogs can distinguish SARS-CoV-2-infections from other viral infections. However, compared to earlier studies our scent dogs achieved lower diagnostic sensitivities. To deploy COVID-19 detection dogs as a reliable screening method it is therefore mandatory to include a variety of samples from different viral respiratory tract infections in dog training to ensure a successful discrimination process.

Simultaneous measurement of liquid-film thickness and solute concentration of aqueous solutions of two urea derivatives using NIR absorption

We present a method to simultaneously measure the film thickness and individual concentrations of two urea derivates (urea CH₄N₂O and dimethylurea C₃H₈N₂O) mixed in an aqueous solution at constant temperature using near-infrared (NIR) absorption at multiple specific wavelengths. Fourier transform infrared (FTIR) spectra of aqueous mixtures of urea and dimethylurea solutions were recorded in the 1250-2500 nm wavelength range in thin-layer quartz cuvettes at room temperature. The spectra reveal suitable detection wavelengths, i.e., 1450, 1933, 2200, and 2270 nm, for which both the absorption coefficient and its variation with the species concentration are large enough to achieve satisfactory detection sensitivity and selectivity. For validation measurements, samples were prepared in thin-layer quartz transmission cells with known path lengths and mixture compositions in the range 100-1000 µm and 0-40 wt.%, respectively. Film thickness and mass fractions of both species were determined from measured absorbance ratios in the determined characteristic wavelength bands.

SARS-CoV-2-Specific Antibodies in Domestic Cats during First COVID-19 Wave, Europe

We conducted a severe acute respiratory syndrome coronavirus 2 antibody seroprevalence study among >2,000 domestic cats from 4 countries during the first coronavirus disease wave in Europe. We found 4.4% seroprevalence using a virus neutralization test and 4.3% using a receptor-binding domain ELISA, demonstrating probable human-to-cat transmission.

Spectroscopy of the frustrated quantum antiferromagnet Cs2CuCl4

We investigate the electronic structure of Cs₂CuCl₄, a material discussed in the framework of a frustrated quantum antiferromagnet, by means of resonant inelastic x-ray scattering (RIXS) and density functional theory (DFT). From the non-dispersive highly localizedddexcitations, we resolve the crystal field splitting of the Cu²⁺ions in a strongly distorted tetrahedral coordination. This allows us to model the RIXS spectrum within the crystal field theory (CFT), assign theddorbital excitations and retrieve experimentally the values of the crystal field splitting parametersD_q,D_sandD_τ. The electronic structure obtainedab-initioagrees with the RIXS spectrum and modelled by CFT, highlighting the potential of combined spectroscopic, cluster and DFT calculations to determine the electronic ground state of complex materials.

Health-economic evaluation of collaborative orthogeriatric care for patients with a hip fracture in Germany: a retrospective cohort study using health and long-term care insurance claims data

BACKGROUND

Evidence suggests benefits of orthogeriatric co-management (OGCM) for hip fracture patients. Yet, evidence on cost-effectiveness is limited and based on small datasets. The aim of our study was to conduct an economic evaluation of the German OGCM for geriatric hip fracture patients.

METHODS

This retrospective cohort study was based on German health and long-term care insurance data. Individuals were 80 years and older, sustained a hip fracture in 2014, and were treated in hospitals providing OGCM (OGCM group) or standard care (control group). Health care costs from payer and societal perspective, life years gained (LYG) and cost-effectiveness were investigated within 1 year. We applied weighted gamma and two-part models, and entropy balancing to account for the lack of randomisation. We calculated incremental cost-effectiveness ratios (ICER) and employed the net-benefit approach to construct cost-effectiveness acceptability curves.

RESULTS

14,005 patients were treated in OGCM, and 10,512 in standard care hospitals. Total average health care costs per patient were higher in the OGCM group: €1181.53 (p < 0.001) from payer perspective, and €1408.21 (p < 0.001) from societal perspective. The ICER equalled €52,378.12/ LYG from payer and €75,703.44/ LYG from societal perspective. The probability for cost-effectiveness would be 95% if the willingness-to-pay was higher than €82,000/ LYG from payer, and €95,000/ LYG from societal perspective.

CONCLUSION

Survival improved in hospitals providing OGCM. Costs were found to increase, driven by inpatient and long-term care. The cost-effectiveness depends on the willingness-to-pay. The ICER is likely to improve with a longer follow-up.

Scent dog identification of SARS-CoV-2 infections in different body fluids

Background

The main strategy to contain the current SARS-CoV-2 pandemic remains to implement a comprehensive testing, tracing and quarantining strategy until vaccination of the population is adequate. Scent dogs could support current testing strategies.

Methods

Ten dogs were trained for 8 days to detect SARS-CoV-2 infections in beta-propiolactone inactivated saliva samples. The subsequent cognitive transfer performance for the recognition of non-inactivated samples were tested on three different body fluids (saliva, urine, and sweat) in a randomised, double-blind controlled study.

Results

Dogs were tested on a total of 5242 randomised sample presentations. Dogs detected non-inactivated saliva samples with a diagnostic sensitivity of 84% (95% CI: 62.5–94.44%) and specificity of 95% (95% CI: 93.4–96%). In a subsequent experiment to compare the scent recognition between the three non-inactivated body fluids, diagnostic sensitivity and specificity were 95% (95% CI: 66.67–100%) and 98% (95% CI: 94.87–100%) for urine, 91% (95% CI: 71.43–100%) and 94% (95% CI: 90.91–97.78%) for sweat, 82% (95% CI: 64.29–95.24%), and 96% (95% CI: 94.95–98.9%) for saliva respectively.

Conclusions

The scent cognitive transfer performance between inactivated and non-inactivated samples as well as between different sample materials indicates that global, specific SARS-CoV-2-associated volatile compounds are released across different body secretions, independently from the patient’s symptoms. All tested body fluids appear to be similarly suited for reliable detection of SARS-CoV-2 infected individuals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06411-1.

Multi-species ELISA for the detection of antibodies against SARS-CoV-2 in animals

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a pandemic with millions of infected humans and hundreds of thousands of fatalities. As the novel disease - referred to as COVID-19 - unfolded, occasional anthropozoonotic infections of animals by owners or caretakers were reported in dogs, felid species and farmed mink. Further species were shown to be susceptible under experimental conditions. The extent of natural infections of animals, however, is still largely unknown. Serological methods will be useful tools for tracing SARS-CoV-2 infections in animals once test systems are evaluated for use in different species. Here, we developed an indirect multi-species ELISA based on the receptor-binding domain (RBD) of SARS-CoV-2. The newly established ELISA was evaluated using 59 sera of infected or vaccinated animals, including ferrets, raccoon dogs, hamsters, rabbits, chickens, cattle and a cat, and a total of 220 antibody-negative sera of the same animal species. Overall, a diagnostic specificity of 100.0% and sensitivity of 98.31% were achieved, and the functionality with every species included in this study could be demonstrated. Hence, a versatile and reliable ELISA protocol was established that enables high-throughput antibody detection in a broad range of animal species, which may be used for outbreak investigations, to assess the seroprevalence in susceptible species or to screen for reservoir or intermediate hosts.

Prolonged SARS-CoV-2 RNA Shedding from Therapy Cat after Cluster Outbreak in Retirement Home

We report a therapy cat in a nursing home in Germany infected with severe acute respiratory syndrome coronavirus 2 during a cluster outbreak in the home residents. Although we confirmed prolonged presence of virus RNA in the asymptomatic cat, genome sequencing showed no further role of the cat in human infections on site.

Post-operative follow-up of 150 patients with sentinel lymph node biopsy under tumescence local anesthesia

BACKGROUND

Sentinel lymph node biopsy (SLNB) is useful for staging of patients with melanoma. Although SLNB is mostly performed under general anesthesia (GA), tumescence local anesthesia (TLA) can also be used. However, less data are available regarding feasibility of SLNB under TLA. Here we present a post-operative follow-up of 150 patients.

PATIENTS AND METHODS

We prospectively analyzed data from 150 patients with primary cutaneous malignant melanoma. We assessed pain, post-operative complications and patients' satisfaction after SLNB under TLA.

RESULTS

32 % of the patients reported post-operative pain within the first 48 h after SLNB. Seroma was the most frequent complication, as 29 seromas after SLNB were observed. Wound infection was observed in 3.3 % of the patients. 98.7 % of the patients were satisfied with SLNB under TLA.

CONCLUSIONS

SLNB under TLA is a safe and feasible option and should be considered for patients with melanoma. Especially with multimorbid or elderly patients, the risks of GA can be avoided.

Impact of morbidity on care need increase and mortality in nursing homes: a retrospective longitudinal study using administrative claims data

Background

A growing number of older people are care dependent and live in nursing homes, which accounts for the majority of long-term-care spending. Specific medical conditions and resident characteristics may serve as risk factors predicting negative health outcomes. We investigated the association between the risk of increasing care need and chronic medical conditions among nursing home residents, allowing for the competing risk of mortality.

Methods

In this retrospective longitudinal study based on health insurance claims data, we investigated 20,485 older adults (≥65 years) admitted to German nursing homes between April 2007 and March 2014 with care need level 1 or 2 (according to the three level classification of the German long-term care insurance). This classification is based on required daily time needed for assistance. The outcome was care level change. Medical conditions were determined according to 31 Charlson and Elixhauser conditions. Competing risks analyses were applied to identify chronic medical conditions associated with risk of care level change and mortality.

Results

The probability for care level change and mortality acted in opposite directions. Dementia was associated with increased probability of care level change compared to other conditions. Patients who had cancer, myocardial infarction, congestive heart failure, cardiac arrhythmias, renal failure, chronic pulmonary disease, weight loss, or recent hospitalization were more likely to die, as well as residents with paralysis and obesity when admitted with care level 2.

Conclusion

This paper identified risk groups of nursing home residents which are particularly prone to increasing care need or mortality. This enables focusing on these risk group to offer prevention or special treatment. Moreover, residents seemed to follow specific trajectories depending on their medical conditions. Some were more prone to increased care need while others had a high risk of mortality instead. Several conditions were neither related to increased care need nor mortality, e.g., valvular, cerebrovascular or liver disease, peripheral vascular disorder, blood loss anemia, depression, drug abuse and psychosis. Knowledge of functional status trajectories of residents over time after nursing home admission can help decision-makers when planning and preparing future care provision strategies (e.g., planning of staffing, physical equipment and financial resources).

Differences in Self-Esteem Between Cat Owners, Dog Owners, and Individuals Without Pets

Introduction: Pet ownership may provide an additional source of social support and may contribute to the owner's self-esteem. Self-esteem is considered a basic human need and is associated with psychological conditions such as depressive symptoms. To date, there is limited knowledge on the association between keeping a pet and self-esteem.

Objectives: The aim of this study was to determine whether cat owners, dog owners, and individuals without pets differ in terms of self-esteem (total sample and stratified by sex).

Methods: Data were taken from the German Aging Survey (wave 5; nationally representative sample of individuals residing in private households ≥40 years). In this survey, the widely used and well-established Rosenberg scale was used to quantify self-esteem. Socioeconomic, lifestyle, and health-related factors were adjusted for in the regression analysis (n = 5,485).

Results: Multiple linear regressions showed that dog owners reported higher self-esteem scores compared to individuals without pets (β = 0.04, p < 0.05). Similarly, male dog owners reported higher self-esteem scores compared to men without pets (β = 0.07, p < 0.01). In contrast, female cat owners reported lower self-esteem scores compared to women without pets (β = −0.07, p < 0.01).

Conclusion: Study findings showed a link between owning a cat and lower self-esteem (women), as well as between owning a dog and higher self-esteem (total sample; men). Future studies should concentrate on investigating the underlying mechanisms. Furthermore, longitudinal studies are needed to better understand the link between animal ownership and self-esteem.

Scent dog identification of samples from COVID-19 patients - a pilot study

BACKGROUND

As the COVID-19 pandemic continues to spread, early, ideally real-time, identification of SARS-CoV-2 infected individuals is pivotal in interrupting infection chains. Volatile organic compounds produced during respiratory infections can cause specific scent imprints, which can be detected by trained dogs with a high rate of precision.

METHODS

Eight detection dogs were trained for 1 week to detect saliva or tracheobronchial secretions of SARS-CoV-2 infected patients in a randomised, double-blinded and controlled study.

RESULTS

The dogs were able to discriminate between samples of infected (positive) and non-infected (negative) individuals with average diagnostic sensitivity of 82.63% (95% confidence interval [CI]: 82.02-83.24%) and specificity of 96.35% (95% CI: 96.31-96.39%). During the presentation of 1012 randomised samples, the dogs achieved an overall average detection rate of 94% (±3.4%) with 157 correct indications of positive, 792 correct rejections of negative, 33 incorrect indications of negative or incorrect rejections of 30 positive sample presentations.

CONCLUSIONS

These preliminary findings indicate that trained detection dogs can identify respiratory secretion samples from hospitalised and clinically diseased SARS-CoV-2 infected individuals by discriminating between samples from SARS-CoV-2 infected patients and negative controls. This data may form the basis for the reliable screening method of SARS-CoV-2 infected people.

Sentinel lymph node biopsy for high-thickness cutaneous squamous cell carcinoma

Squamous cell carcinomas are among the most common skin tumors and show a risk of metastasis depending on various factors such as tumor thickness, localization, histological subtype and immune status of the patient. Sentinel lymph node biopsy (SLNB) SLNB represents a possibility for assessing the locoregional lymph node status. In this study, the role of the SLNB in lymph node status and survival was analyzed. Retrospectively, 720 patients with high-risk squamous cell carcinoma (tumor thickness > 5 mm) were examined. 150 patients agreed to SLNB, 570 patients did not undergo histologic confirmation of lymph node status and were included directly in follow-up. In 101 patients, a sentinel lymph node was successfully marked and extirpated, followed by regular follow-up examinations.A total of 11.11% of the patients showed lymph node metastasis in the course of their treatment, with no difference in the proportion of patients in the SLNB group (11.9%) and the observation group (11.4%) (p = 0.873). The proportion of distant metastasis also did not differ between the groups (p = 0.898). In 3.96% of the patients in the SLNB group, a metastasis was found in the sentinel lymph node. Tumor-specific death was observed in 7.14% of the patients in the SLNB group and 4.74% in the observation group (p = 0.269). Although SLNB is a principally suitable method for determining lymph node status, the available data do not provide any benefit regarding further metastasis or tumor-specific survival.

Analysis of mortality after hip fracture on patient, hospital, and regional level in Germany

Knowledge about risk factors of mortality after hip fracture might encourage prevention and further improvements in care. This study identified patient risk factors as well as hospital and regional characteristics associated with a decreased risk. Variation of mortality was largest on patient level and modest on hospital and regional level.

INTRODUCTION

Among numerous studies analyzing mortality as worst consequence after hip fracture, the majority focused on patient level and fewer on hospital and regional level. Comprehensive knowledge about contributing factors on all levels might help to reveal relevant inequalities, which would encourage prevention and further improvements in care. This study aimed at investigating variation of mortality after hip fracture on patient, hospital, and regional level in Germany.

METHODS

We performed a retrospective cohort study on hip fracture patients aged 65 and older using statutory health insurance claims data from Jan 2009 through Dec. 2012 and additional information from the Federal Statistical Office Germany. Regions were classified based on two-digit postal code. We applied a multilevel Cox proportional hazard model with random intercepts on hospital and regional level to investigate the risk factors for mortality within 6 and 12 months after hip fracture.

RESULTS

The dataset contained information on 123,119 hip fracture patients in 1014 hospitals in 95 German regions. Within 6/12 months, 20.9%/27.6% of the patients died. On patient level, male sex, increasing age, increased pre-fracture care level, and increasing comorbidity were associated with an increased hazard of mortality. Hospitals with increasing hip fracture volume or with orthogeriatric co-management and regions with increased population density were associated with a decreased hazard. Variation was largest on patient level and rather modest on hospital and regional level.

CONCLUSIONS

The identification of patient-related risk factors enables prognosticating mortality after hip fracture. After adjusting for those, variation seemed to be attributable rather to hospitals than to regions.

The Association Between Orthogeriatric Co-Management and Mortality Following Hip Fracture

BACKGROUND

To meet the special needs of older patients with fragility fractures, models for collaborative orthogeriatric care have been developed. The objective of our study was to analyze the association of orthogeriatric co-management with mortality following hip fracture in older patients in Germany.

METHODS

This observational study was based on health insurance claims data from 58 001 patients (79.4% women) aged ≥80 years admitted to the hospital with hip fracture between January 2014 and March 2016. They were treated in 828 German hospitals with or without orthogeriatric co-management. The outcome measure was cumulative mortality with adjustment of the regression analyses.

RESULTS

The crude 30-day mortality was 10.3% for patients from hospitals with orthogeriatric co-management and 13.4% for patients from hospitals without orthogeriatric co-management. The adjusted 30-day mortality was 22% lower for patients in hospitals with orthogeriatric co-management (rate ratio 0.78; 95% CI [0.74; 0.82]; adjusted absolute difference -2.48%; 95% CI [-2.98; -1.98]). The difference in 30-day mortality remained nearly unchanged over the first 6 months. The risk reduction with orthogeriatric co-management was consistently observed in both women and men, across age groups, and in patients with and without care needs. The mean length of the index stay was 19.8 days in hospitals with orthogeriatric co-management and 14.4 days in hospitals without orthogeriatric co-management.

CONCLUSION

A multidisciplinary orthogeriatric approach is associated with lower mortality and a longer index stay in hospital after hip fracture.

Regional variation of care dependency after hip fracture in Germany: A retrospective cohort study using health insurance claims data

Objective

To investigate variation of care dependency after hip fracture across German regions based on the assessment by the German statutory long-term care insurance.

Data sources/study setting

Patient-level statutory health and long-term care insurance claims data from 2009–2011 and official statistical data from Germany.

Study design

We performed a retrospective cohort study. Investigated multinomial outcome categories were increase in care dependency (new onset or a higher care dependency than pre-fracture), no change as reference and death as competing risk in the quarterly period following hip fracture (follow-up 3 months). Regional variation was operationalized with the variance of regional-level random intercepts based on generalized linear mixed models. We adjusted for patient and regional characteristics.

Principal findings

The study included 122,887 hip fracture patients in 95 German postal code regions. Crude outcomes were 30.87% increase in care dependency and 14.35% death. Results indicated modest variation on regional level. Male sex, increasing age, increasing comorbidity, pertrochanteric and subtrochanteric fracture site compared to femoral neck, time from hospital admission to surgery of 3 or more days, as well as increasing inpatient length of stay, non-participation in rehabilitation and regions with lower hospital density were positively associated with an increase in care dependency.

Conclusions

Several characteristics on patient and regional level associated with the outcome were identified. Variation in the increase in care dependency after hip fracture appeared to be attributable primarily to patient characteristics. Variation on regional level was only modest.

Acute care models for hip fracture treatment vs post-acute rehabilitation services in older adults after hip fracture: A comparative claims data analysis from Germany

OBJECTIVE

Acute geriatric care (geriatric early rehabilitative treatment) and sub-acute (inpatient) geriat-ric rehabilitation are delivered to geriatric patients in Germany after hip fracture. The aim of this study was to compare patients' outcomes after hip fracture between 3 German federal states (Hesse, Bavaria, and Baden-Wuerttemberg) that nearly exclusively offered one of the two geriatric care systems.

DESIGN

Retrospective cohort study with patient-related health insurance claims data.

PATIENTS

Analyses were performed with data from 2009-2012 of over 30,000 patients aged ≥80 years with incident hip fracture.

METHODS

Primary outcomes: "increase in care dependency", "nursing home admission"; secondary outcomes: "rehospitalization", "mortality". Multivariate regression models were applied.

RESULTS

Compared with Hesse, the state with acute geriatric care, the risks of an "increase in care dependency" were lower in Bavaria (adjusted ratio = 0.84; 95% confidence interval (95% CI) 0.81-0.87) and Baden-Wurttemberg (0.88; 0.85-0.92), the 2 federal states with sub-acute geriatric rehabilitation. A reduction in the risk of nursing home admission was observed in Baden-Wuerttemberg (0.77; 95% CI 0.69-0.87), but not in Bavaria. Rehospitalization rates were lower in Bavaria and Baden-Wuerttemberg compared with Hesse. There was no difference in mortality.

CONCLUSION

Some, but not all, outcomes were more favourable in the federal states with sub-acute geriatric rehabilitation than in the federal state with acute geriatric care.

Treatment utilization and treatment barriers in individuals with body dysmorphic disorder

BACKGROUND

Although effective treatments are available, most individuals with body dysmorphic disorder (BDD) do not receive an appropriate diagnosis or treatment. We aimed to examine treatment utilization and barriers to treatment, and to identify associated socio-demographic and clinical characteristics.

METHODS

German individuals completed an online self-report survey of appearance concerns. A sample of N = 429 individuals met criteria for BDD. We examined the frequency of treatment utilization and barriers, analyzed comparisons between treated and untreated individuals and assessed the relationships of socio-demographic and clinical features with mental health treatment utilization and treatment barriers, respectively.

RESULTS

Only 15.2% of the individuals with BDD had been diagnosed with BDD, and lifetime rates of mental health treatment were low (39.9%). Individuals endorsed multiple barriers to mental health treatment, especially shame, low perceived need and a preference for cosmetic and medical treatments. Associated features were identified, including age, a BDD diagnosis, body dysmorphic symptom severity, a likely major depressive disorder, prior cosmetic surgery, and insight.

CONCLUSIONS

The results of this largest study to date highlight that BDD is still underrecognized and undertreated even in a country with extensive mental health care and few financial barriers. We discuss modifiable factors and strategies to foster awareness of BDD in sufferers and professionals to improve treatment dissemination and to reduce treatment barriers.

Eradication of Peste des Petits Ruminants Virus and the Wildlife-Livestock Interface

Growing evidence suggests that multiple wildlife species can be infected with peste des petits ruminants virus (PPRV), with important consequences for the potential maintenance of PPRV in communities of susceptible hosts, and the threat that PPRV may pose to the conservation of wildlife populations and resilience of ecosystems. Significant knowledge gaps in the epidemiology of PPRV across the ruminant community (wildlife and domestic), and the understanding of infection in wildlife and other atypical host species groups (e.g., camelidae, suidae, and bovinae) hinder our ability to apply necessary integrated disease control and management interventions at the wildlife-livestock interface. Similarly, knowledge gaps limit the inclusion of wildlife in the FAO/OIE Global Strategy for the Control and Eradication of PPR, and the framework of activities in the PPR Global Eradication Programme that lays the foundation for eradicating PPR through national and regional efforts. This article reports on the first international meeting on, "Controlling PPR at the livestock-wildlife interface," held in Rome, Italy, March 27-29, 2019. A large group representing national and international institutions discussed recent advances in our understanding of PPRV in wildlife, identified knowledge gaps and research priorities, and formulated recommendations. The need for a better understanding of PPRV epidemiology at the wildlife-livestock interface to support the integration of wildlife into PPR eradication efforts was highlighted by meeting participants along with the reminder that PPR eradication and wildlife conservation need not be viewed as competing priorities, but instead constitute two requisites of healthy socio-ecological systems.

Detrimental Role of Neutrophil Extracellular Traps during Dengue Virus Infection

A recent article by Sung et al. identified the CLEC2 platelet receptor as an important factor of lethal dengue virus infection. Formation of neutrophil extracellular traps via crosstalk with CLEC5A and TLR2 neutrophils were ascribed a causative role in DENV infection. This provides new insights for the development of candidate broad-spectrum therapies against hemorrhagic virus infections.

P6303Developmental origin of cardiac macrophages in steady state and myocardial infarction

Background

Macrophages are the most abundant immune cells in the myocardial tissue in steady state. The sterile inflammation caused by myocardial infarction triggers a massive immune reaction, which leads to a profound influx of neutrophils and monocytes. In the postacute phase of infarction macrophages play an essential role in reparative processes. Recently, it has become clear that macrophages in the heart have a dual developmental origin from embryonic and bone marrow (BM) hematopoiesis. In this study, we sought to investigate the contribution of embryonic derived macrophages to the cardiac macrophage pool in steady state as well as the acute and chronic phase after ischemia/reperfusion injury.

Methods/Results

To address the origin of macrophages in steady state we used different models of lineage tracing to determine the developmental origin of cardiac macrophages. Using FLT3-Cre mice and radiation-independent CD45.1/.2 bone marrow chimera, we found that the resident macrophage population in the heart is mainly independent of definitive hematopoiesis (approximately 70–80% of cardiac macrophages). The BM-dependent population on the other hand is replenished by blood-derived monocytes.

Further we used the radiation-independent CD45.1/.2 bone marrow chimera to characterize the origin of macrophages at different time points after I/R-injury. In the acute phase after myocardial infarction we observed a profound influx of BM-derived macrophages in the infarct region and also in the remote area. 30 days after I/R-injury the composition of the resident macrophage pool was mainly comprised of BM-independent macrophages, similar to steady state conditions. To address the role of BM-derived macrophages we used CCR2-ko mice, which have low numbers of inflammatory monocytes in peripheral blood. CCR2-ko mice showed reduced macrophage numbers in the acute phase after myocardial infarction. Using positron emission tomography we investigated the influence of CCR2-deficiency on cardiac function after I/R-injury. In comparison to WT mice, CCR2-ko mice showed a significantly increased infarct size. Cardiac remodeling, determined by end-diastolic volume, on the other hand was improved in CCR2-ko mice. The ejection fraction was similar in both groups.

Conclusion

The cardiac macrophage pool is mainly comprised of BM-independent macrophages. In response to I/R-injury monocyte-derived macrophages transiently enter the myocardium but do not persist in significant numbers over time. The influx of BM-derived macrophages after I/R-injury was reduced using CCR2-ko mice, which led to improved cardiac remodeling.

Our findings are of potential importance for understanding the cardiac immune response and for the therapeutic targeting of macrophages in inflammatory conditions.

Acknowledgement/Funding

German Society of Cardiology, German Centre for Cardiovascular Research, LMU Excellence, SFB 914