Correction: State-of-the-art analytical methods of viral infections in human lung organoids

[This corrects the article DOI: 10.1371/journal.pone.0276115.].

State-of-the-art analytical methods of viral infections in human lung organoids

Human-based organ models can provide strong predictive value to investigate the tropism, virulence, and replication kinetics of viral pathogens. Currently, such models have received widespread attention in the study of SARS-CoV-2 causing the COVID-19 pandemic. Applicable to a large set of organoid models and viruses, we provide a step-by-step work instruction for the infection of human alveolar-like organoids with SARS-CoV-2 in this protocol collection. We also prepared a detailed description on state-of-the-art methodologies to assess the infection impact and the analysis of relevant host factors in organoids. This protocol collection consists of five different sets of protocols. Set 1 describes the protein extraction from human alveolar-like organoids and the determination of protein expression of angiotensin-converting enzyme 2 (ACE2), transmembrane serine protease 2 (TMPRSS2) and FURIN as exemplary host factors of SARS-CoV-2. Set 2 provides detailed guidance on the extraction of RNA from human alveolar-like organoids and the subsequent qPCR to quantify the expression level of ACE2, TMPRSS2, and FURIN as host factors of SARS-CoV-2 on the mRNA level. Protocol set 3 contains an in-depth explanation on how to infect human alveolar-like organoids with SARS-CoV-2 and how to quantify the viral replication by plaque assay and viral E gene-based RT-qPCR. Set 4 provides a step-by-step protocol for the isolation of single cells from infected human alveolar-like organoids for further processing in single-cell RNA sequencing or flow cytometry. Set 5 presents a detailed protocol on how to perform the fixation of human alveolar-like organoids and guides through all steps of immunohistochemistry and in situ hybridization to visualize SARS-CoV-2 and its host factors. The infection and all subsequent analytical methods have been successfully validated by biological replications with human alveolar-like organoids based on material from different donors.

Human lungs show limited permissiveness for SARS-CoV-2 due to scarce ACE2 levels but virus-induced expansion of inflammatory macrophages

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilises the angiotensin-converting enzyme 2 (ACE2) transmembrane peptidase as cellular entry receptor. However, whether SARS-CoV-2 in the alveolar compartment is strictly ACE2-dependent and to what extent virus-induced tissue damage and/or direct immune activation determines early pathogenesis is still elusive.

METHODS

Spectral microscopy, single-cell/-nucleus RNA sequencing or ACE2 "gain-of-function" experiments were applied to infected human lung explants and adult stem cell derived human lung organoids to correlate ACE2 and related host factors with SARS-CoV-2 tropism, propagation, virulence and immune activation compared to SARS-CoV, influenza and Middle East respiratory syndrome coronavirus (MERS-CoV). Coronavirus disease 2019 (COVID-19) autopsy material was used to validate ex vivo results.

RESULTS

We provide evidence that alveolar ACE2 expression must be considered scarce, thereby limiting SARS-CoV-2 propagation and virus-induced tissue damage in the human alveolus. Instead, ex vivo infected human lungs and COVID-19 autopsy samples showed that alveolar macrophages were frequently positive for SARS-CoV-2. Single-cell/-nucleus transcriptomics further revealed nonproductive virus uptake and a related inflammatory and anti-viral activation, especially in "inflammatory alveolar macrophages", comparable to those induced by SARS-CoV and MERS-CoV, but different from NL63 or influenza virus infection.

CONCLUSIONS

Collectively, our findings indicate that severe lung injury in COVID-19 probably results from a macrophage-triggered immune activation rather than direct viral damage of the alveolar compartment.

Clinical presentation, disease course, and outcome of COVID-19 in hospitalized patients with and without pre-existing cardiac disease: a cohort study across 18 countries

AIMS

Patients with cardiac disease are considered high risk for poor outcomes following hospitalization with COVID-19. The primary aim of this study was to evaluate heterogeneity in associations between various heart disease subtypes and in-hospital mortality.

METHODS AND RESULTS

We used data from the CAPACITY-COVID registry and LEOSS study. Multivariable Poisson regression models were fitted to assess the association between different types of pre-existing heart disease and in-hospital mortality. A total of 16 511 patients with COVID-19 were included (21.1% aged 66-75 years; 40.2% female) and 31.5% had a history of heart disease. Patients with heart disease were older, predominantly male, and often had other comorbid conditions when compared with those without. Mortality was higher in patients with cardiac disease (29.7%; n = 1545 vs. 15.9%; n = 1797). However, following multivariable adjustment, this difference was not significant [adjusted risk ratio (aRR) 1.08, 95% confidence interval (CI) 1.02-1.15; P = 0.12 (corrected for multiple testing)]. Associations with in-hospital mortality by heart disease subtypes differed considerably, with the strongest association for heart failure (aRR 1.19, 95% CI 1.10-1.30; P < 0.018) particularly for severe (New York Heart Association class III/IV) heart failure (aRR 1.41, 95% CI 1.20-1.64; P < 0.018). None of the other heart disease subtypes, including ischaemic heart disease, remained significant after multivariable adjustment. Serious cardiac complications were diagnosed in <1% of patients.

CONCLUSION

Considerable heterogeneity exists in the strength of association between heart disease subtypes and in-hospital mortality. Of all patients with heart disease, those with heart failure are at greatest risk of death when hospitalized with COVID-19. Serious cardiac complications are rare during hospitalization.

[Minor Victims of Violent Acts in the Context of the Victim Reparation Law]

OBJECTIVE

A descriptive analysis of victim compensation applications for children and adolescents as well as sociodemographic and trauma-specific information concerning victims and perpetrators.

METHOD

We did analysis of 100 victim-compensation application files based on a self-developed category system.

RESULTS

The files included solely interpersonal trauma, 59 % of which are type II trauma. The most frequent form is sexual violence. The perpetrators stem mostly from children’s homes or peripherals. 79 % of the victims received a diagnosis of a mental disorder, most often posttraumatic stress disorder.

CONCLUSIONS

Sexually abused children and adolescents make up the majority of the target population in OEG-related trauma outpatient units. Such outpatient units should therefore offer a specific expertise in treating sexually abused children and adolescents.

[Neuromyelitis optica spectrum disorder and pregnancy]

BACKGROUND

Neuromyelitis optica spectrum disorders (NMOSD) are autoimmune inflammatory diseases of the central nervous system that mainly affect women. In some of these patients NMOSD occurs during fertile age. For this reason, treating physicians may be confronted with questions concerning family planning, pregnancy and birth.

OBJECTIVE

This study provides an overview on the influence of NMOSD on fertility, pregnancy complications and pregnancy outcome. The effect of pregnancy on NMOSD course and therapy options during pregnancy are discussed.

MATERIAL AND METHODS

A search of the current literature was carried out using the PubMed database.

RESULTS AND CONCLUSION

Animal studies have shown lower fertility rates in NMOSD; however, studies investigating fertility in NMOSD patients are lacking. Pregnancy in NMOSD patients are associated with an increase in postpartum disease activity and a higher grade of disability after pregnancy. Some studies showed higher risks of pregnancy complications e. g. spontaneous abortions and preeclampsia. With a few limitations, acute relapses during pregnancy can be treated with methylprednisolone and/or plasma exchange/immunoadsorption. Stopping or continuing immunosuppressive therapy with azathioprine or rituximab during pregnancy should be critically weighed considering previous and current disease activity. Therefore, a joint supervision by a specialized center is recommended, particularly in specific situations such as pregnancy.

[Monitoring of blood parameters under course-modified MS therapy : Substance-specific relevance and current recommendations for action]

With the approval of various substances for the immunotherapy of multiple sclerosis (MS), treatment possibilities have improved significantly over the last few years. Indeed, the choice of individually tailored preparations and treatment monitoring for the treating doctor is becoming increasingly more complex. This is particularly applicable for monitoring for a treatment-induced compromise of the immune system. The following article by members of the German Multiple Sclerosis Skills Network (KKNMS) and the task force "Provision Structures and Therapeutics" summarizes the practical recommendations for approved immunotherapy for mild to moderate and for (highly) active courses of MS. The focus is on elucidating the substance-specific relevance of particular laboratory parameters with regard to the mechanism of action and the side effects profile. To enable appropriate action to be taken in clinical practice, any blood work changes that can be expected, in addition to any undesirable laboratory findings and their causes and relevance, should be elucidated.

Increasing the inspiratory time and I:E ratio during mechanical ventilation aggravates ventilator-induced lung injury in mice

Introduction

Lung-protective ventilation reduced acute respiratory distress syndrome (ARDS) mortality. To minimize ventilator-induced lung injury (VILI), tidal volume is limited, high plateau pressures are avoided, and positive end-expiratory pressure (PEEP) is applied. However, the impact of specific ventilatory patterns on VILI is not well defined. Increasing inspiratory time and thereby the inspiratory/expiratory ratio (I:E ratio) may improve oxygenation, but may also be harmful as the absolute stress and strain over time increase. We thus hypothesized that increasing inspiratory time and I:E ratio aggravates VILI.

Methods

VILI was induced in mice by high tidal-volume ventilation (HV_T 34 ml/kg). Low tidal-volume ventilation (LV_T 9 ml/kg) was used in control groups. PEEP was set to 2 cm H₂O, FiO₂ was 0.5 in all groups. HV_T and LV_T mice were ventilated with either I:E of 1:2 (LV_T 1:2, HV_T 1:2) or 1:1 (LV_T 1:1, HV_T 1:1) for 4 hours or until an alternative end point, defined as mean arterial blood pressure below 40 mm Hg. Dynamic hyperinflation due to the increased I:E ratio was excluded in a separate group of animals. Survival, lung compliance, oxygenation, pulmonary permeability, markers of pulmonary and systemic inflammation (leukocyte differentiation in lung and blood, analyses of pulmonary interleukin-6, interleukin-1β, keratinocyte-derived chemokine, monocyte chemoattractant protein-1), and histopathologic pulmonary changes were analyzed.

Results

LV_T 1:2 or LV_T 1:1 did not result in VILI, and all individuals survived the ventilation period. HV_T 1:2 decreased lung compliance, increased pulmonary neutrophils and cytokine expression, and evoked marked histologic signs of lung injury. All animals survived. HV_T 1:1 caused further significant worsening of oxygenation, compliance and increased pulmonary proinflammatory cytokine expression, and pulmonary and blood neutrophils. In the HV_T 1:1 group, significant mortality during mechanical ventilation was observed.

Conclusion

According to the “baby lung” concept, mechanical ventilation-associated stress and strain in overinflated regions of ARDS lungs was simulated by using high tidal-volume ventilation. Increase of inspiratory time and I:E ratio significantly aggravated VILI in mice, suggesting an impact of a “stress/strain × time product” for the pathogenesis of VILI. Thus increasing the inspiratory time and I:E ratio should be critically considered.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0759-2) contains supplementary material, which is available to authorized users.

Mechanical ventilation drives pneumococcal pneumonia into lung injury and sepsis in mice: protection by adrenomedullin

Introduction

Ventilator-induced lung injury (VILI) contributes to morbidity and mortality in acute respiratory distress syndrome (ARDS). Particularly pre-injured lungs are susceptible to VILI despite protective ventilation. In a previous study, the endogenous peptide adrenomedullin (AM) protected murine lungs from VILI. We hypothesized that mechanical ventilation (MV) contributes to lung injury and sepsis in pneumonia, and that AM may reduce lung injury and multiple organ failure in ventilated mice with pneumococcal pneumonia.

Methods

We analyzed in mice the impact of MV in established pneumonia on lung injury, inflammation, bacterial burden, hemodynamics and extrapulmonary organ injury, and assessed the therapeutic potential of AM by starting treatment at intubation.

Results

In pneumococcal pneumonia, MV increased lung permeability, and worsened lung mechanics and oxygenation failure. MV dramatically increased lung and blood cytokines but not lung leukocyte counts in pneumonia. MV induced systemic leukocytopenia and liver, gut and kidney injury in mice with pneumonia. Lung and blood bacterial burden was not affected by MV pneumonia and MV increased lung AM expression, whereas receptor activity modifying protein (RAMP) 1–3 expression was increased in pneumonia and reduced by MV. Infusion of AM protected against MV-induced lung injury (66% reduction of pulmonary permeability p < 0.01; prevention of pulmonary restriction) and against VILI-induced liver and gut injury in pneumonia (91% reduction of AST levels p < 0.05, 96% reduction of alanine aminotransaminase (ALT) levels p < 0.05, abrogation of histopathological changes and parenchymal apoptosis in liver and gut).

Conclusions

MV paved the way for the progression of pneumonia towards ARDS and sepsis by aggravating lung injury and systemic hyperinflammation leading to liver, kidney and gut injury. AM may be a promising therapeutic option to protect against development of lung injury, sepsis and extrapulmonary organ injury in mechanically ventilated individuals with severe pneumonia.

Neuromyelitis optica and pregnancy during therapeutic B cell depletion: infant exposure to anti-AQP4 antibody and prevention of rebound relapses with low-dose rituximab postpartum

Neuromyelitis optica (NMO) predominantly affects women, some in childbearing age, and requires early therapeutic intervention to prevent disabling relapses. We report an anti-AQP4 antibody-seropositive patient who became pregnant seven months after low-dose (100 mg) rituximab application. Pregnancy showed no complications, and low-dose rituximab restarted two days after delivery resulted in neurological stability for 24 months. Remarkably, her otherwise healthy newborn presented with anti-AQP4 antibody and reduced B lymphocyte counts in umbilical cord blood, which normalized three months later. Confirming and extending previous reports, our case suggests that low-dose rituximab might be compatible with pregnancy and prevent rebound NMO disease activity postpartum.

Natalizumab treatment during pregnancy - effects on the neonatal immune system

BACKGROUND

Pregnancies in women with severe relapsing-remitting multiple sclerosis treated with natalizumab constitute a major challenge, because withdrawal of the drug may cause relapses but continuation might have unknown effects on the infantile immune system.

AIMS OF THE STUDY

To identify the impact of maternal natalizumab treatment during pregnancy on basic immune functions of the newborn.

METHODS

Basic immunological testing and assessment of the chemotaxis rate of freshly isolated T lymphocytes in the presence and absence of CXCL12 was performed in two neonates, whose mothers were treated with natalizumab until the 34th week of pregnancy (pw).

RESULTS

Both children had an uneventful birth. However, a reduction in the CXCL12-induced T-cell chemotaxis was found in both children. In contrast, the chemotaxis rate of unstimulated T lymphocytes was not altered. The distribution of the lymphocyte subpopulations was investigated only in case 1 and was normal.

CONCLUSIONS

Here, we present to our knowledge the first assessment of T lymphocytes chemotaxis rate in two natalizumab-exposed newborns. A significant reduction in the CXCL12-induced chemotaxis rate of T lymphocytes has been observed and may compromise host defence function in early life. More clinical and immunological data on natalizumab-exposed neonates are warranted.

Anti-JC virus antibodies in a large German natalizumab-treated multiple sclerosis cohort

OBJECTIVE

To investigate the rate of seropositivity of anti-JC virus (JCV) antibodies in a German multiple sclerosis (MS) cohort treated with natalizumab in the postmarketing setting and to assess anti-JCV serostatus in samples obtained before diagnosis of progressive multifocal leukoencephalopathy (PML).

METHODS

This was a blinded, retrospective cross-sectional and longitudinal analysis for anti-JCV antibodies using a confirmatory 2-step ELISA on 2,782 blood samples obtained from 2,253 patients nationwide for routine testing for anti-natalizumab antibodies during open-label treatment between 2007 and 2010.

RESULTS

Of the natalizumab-treated patients with MS, 58.8% tested positive for anti-JCV antibodies. The rate of seropositivity was higher in males and increased with age, with a plateau between age intervals 20-29 and 30-39 years. In longitudinal analyses, 19 of 194 (9.8%) patients converted from anti-JCV antibody-negative to seropositive status over 7.7 months; 4.7% reverted from antibody-positive to seronegative status over 7.9 months. Antibody levels, especially in the latter group, were low, indicating fluctuations around the lower cut point of the assay. Neither anti-JCV serostatus nor antibody levels were associated with immunosuppressive pretreatment, duration of natalizumab treatment, or anti-natalizumab antibodies. All samples obtained from 10 patients who developed PML were seropositive (13 samples before PML diagnosis [2.0-37.6 months]; 2 samples at diagnosis). Antibody levels in these samples were higher than those in samples from seropositive patients who did not develop PML.

CONCLUSIONS

These data argue for the potential clinical utility of JCV serology for PML risk stratification. However, further investigations of fluctuations in serostatus and of antibody levels for a more precise understanding of the predictive value are warranted.

Intermedin stabilized endothelial barrier function and attenuated ventilator-induced lung injury in mice

BACKGROUND

Even protective ventilation may aggravate or induce lung failure, particularly in preinjured lungs. Thus, new adjuvant pharmacologic strategies are needed to minimize ventilator-induced lung injury (VILI). Intermedin/Adrenomedullin-2 (IMD) stabilized pulmonary endothelial barrier function in vitro. We hypothesized that IMD may attenuate VILI-associated lung permeability in vivo.

METHODOLOGY/PRINCIPAL FINDINGS

Human pulmonary microvascular endothelial cell (HPMVEC) monolayers were incubated with IMD, and transcellular electrical resistance was measured to quantify endothelial barrier function. Expression and localization of endogenous pulmonary IMD, and its receptor complexes composed of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs) 1-3 were analyzed by qRT-PCR and immunofluorescence in non ventilated mouse lungs and in lungs ventilated for 6 h. In untreated and IMD treated mice, lung permeability, pulmonary leukocyte recruitment and cytokine levels were assessed after mechanical ventilation. Further, the impact of IMD on pulmonary vasoconstriction was investigated in precision cut lung slices (PCLS) and in isolated perfused and ventilated mouse lungs. IMD stabilized endothelial barrier function in HPMVECs. Mechanical ventilation reduced the expression of RAMP3, but not of IMD, CRLR, and RAMP1 and 2. Mechanical ventilation induced lung hyperpermeability, which was ameliorated by IMD treatment. Oxygenation was not improved by IMD, which may be attributed to impaired hypoxic vasoconstriction due to IMD treatment. IMD had minor impact on pulmonary leukocyte recruitment and did not reduce cytokine levels in VILI.

CONCLUSIONS/SIGNIFICANCE

IMD may possibly provide a new approach to attenuate VILI.

Accidental natalizumab administration to the third trimester of pregnancy in an adolescent patient with multiple sclerosis

BACKGROUND

Natalizumab is neither licensed for the use in adolescents nor during pregnancy. There are no reports of accidental natalizumab exposure during pregnancy continued as long as to the third trimester of pregnancy.

AIMS

We report the outcome of pregnancy in a 17-year-old adolescent patient with multiple sclerosis (MS) treated with natalizumab from the age of 16, who was diagnosed to be pregnant in the 31st gestational week (gw) of pregnancy. To our knowledge, this report describes the first patient receiving natalizumab to the third trimester of pregnancy.

CASE REPORT

  Because of high relapse activity, natalizumab treatment was administered in an adolescent patient with MS. Pregnancy was diagnosed in the 31st gw after 17 natalizumab infusions, seven of them accidentally during pregnancy.

RESULTS

Pre- and postnatal development of the child was normal.

CONCLUSIONS

The case reported indicates that accidentally continued natalizumab treatment until few weeks before delivery may have no negative impact on the developing foetus.

Dissection of a type I interferon pathway in controlling bacterial intracellular infection in mice

Defence mechanisms against intracellular bacterial pathogens are incompletely understood. Our study characterizes a type I IFN-dependent cell-autonomous defence pathway directed against Legionella pneumophila, an intracellular model organism and frequent cause of pneumonia. We show that macrophages infected with L. pneumophila produced IFNβ in a STING- and IRF3- dependent manner. Paracrine type I IFNs stimulated upregulation of IFN-stimulated genes and a cell-autonomous defence pathway acting on replicating and non-replicating Legionella within their specialized vacuole. Our infection experiments in mice lacking receptors for type I and/or II IFNs show that type I IFNs contribute to expression of IFN-stimulated genes and to bacterial clearance as well as resistance in L. pneumophila pneumonia in addition to type II IFN. Overall, our study shows that paracrine type I IFNs mediate defence against L. pneumophila, and demonstrates a protective role of type I IFNs in in vivo infections with intracellular bacteria.

Simvastatin attenuates ventilator-induced lung injury in mice

INTRODUCTION

Mechanical ventilation (MV) is a life saving intervention in acute respiratory failure without alternative. However, particularly in pre-injured lungs, even protective ventilation strategies may evoke ventilator-induced lung injury (VILI), which is characterized by pulmonary inflammation and vascular leakage. Adjuvant pharmacologic strategies in addition to lung protective ventilation to attenuate VILI are lacking. Simvastatin exhibited anti-inflammatory and endothelial barrier stabilizing properties in vitro and in vivo.

METHODS

Mice were ventilated (12 ml/kg; six hours) and subjected to simvastatin (20 mg/kg) or sham treatment. Pulmonary microvascular leakage, oxygenation, pulmonary and systemic neutrophil and monocyte counts and cytokine release in lung and blood plasma were assessed. Further, lung tissue was analyzed by electron microscopy.

RESULTS

Mechanical ventilation induced VILI, displayed by increased pulmonary microvascular leakage and endothelial injury, pulmonary recruitment of neutrophils and Gr-1high monocytes, and by liberation of inflammatory cytokines in the lungs. Further, VILI associated systemic inflammation characterized by blood leukocytosis and elevated plasma cytokines was observed. Simvastatin treatment limited pulmonary endothelial injury, attenuated pulmonary hyperpermeability, prevented the recruitment of leukocytes to the lung, reduced pulmonary cytokine levels and improved oxygenation in mechanically ventilated mice.

CONCLUSIONS

High-dose simvastatin attenuated VILI in mice by reducing MV-induced pulmonary inflammation and hyperpermeability.