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.

Reversion of Pneumolysin-Induced Executioner Caspase Activation Redirects Cells to Survival.

Apoptosis is an indispensable mechanism for eliminating infected cells and activation of executioner caspases is considered to be a point of no return. Streptococcus pneumoniae, the most common bacterial pathogen causing community-acquired pneumonia, induces apoptosis via its pore-forming toxin pneumolysin, leading to rapid influxes of mitochondrial calcium [Ca2+]m as well as fragmentation, and loss of motility and membrane potential, which is accompanied by caspase-3/7 activation. Using machine-learning and quantitative live-cell microscopy, we identified a significant number of alveolar epithelial cells surviving such executioner caspase activation after pneumolysin attack. Precise single-cell analysis revealed the [Ca2+]m amplitude and efflux rate as decisive parameters for survival and death, which was verified by pharmacological inhibition of [Ca2+]m efflux shifting the surviving cells towards the dying fraction. Taken together, we identified the regulation of [Ca2+]m as critical for controlling the cellular fate under pneumolysin attack, which might be useful for therapeutic intervention during pneumococcal infection.

The everlasting issue of prolonged air leaks after lobectomy for non-small cell lung cancer: A data-driven prevention planning model in the era of minimally invasive approaches.

BACKGROUND AND OBJECTIVES: Prolonged air leaks (PAL) are the most frequent complication after lobectomy for non-small cell lung cancer, even in case of minimally invasive approaches. We developed a novel score to identify high-risk patients for PAL during minimally invasive lobectomy. METHODS: A dedicated database was created. We investigated preoperative candidate features and specific intraoperative variables. Univariate and subsequent logistic regression analysis with bootstrap resampling have been used. Model performance has been assessed by reckoning the area under the receiver operating characteristics curve and the Hosmer-Lemeshow goodness of fit. RESULTS: PAL (>5 days) occurred in 72 (15.69%) patients. Five variables emerged from the model. Each one was assigned a score to provide a cumulative scoring system: forced expiratory volume in 1 second below 86% (P = 0.004, 1.5 points), body mass index <24 ( P = 0.002, 1 point), active smoking ( P = 0.001, 1.5 points), incomplete fissures ( P = 0.004, 1.5 points), and adhesions ( P = 0.0001, 1 point). The new score provided a stratification into four risk classes. CONCLUSIONS: The risk score incorporates either general or more specific variables, providing a risk stratification that could be readily applied intra- and postoperatively. Henceforth, specific technical and management measures could be properly allocated to curb PAL.

Tyk2 as a target for immune regulation in human viral/bacterial pneumonia.

The severity and lethality of influenza A virus (IAV) infections is frequently aggravated by secondary bacterial pneumonia. However, the mechanisms in human lung tissue that provoke this increase in fatality are unknown and therapeutic immune modulatory options are lacking.We established a human lung ex vivo co-infection model to investigate innate immune related mechanisms contributing to the susceptibility of secondary pneumococcal pneumonia.We revealed that type I and III interferon (IFN) inhibits Streptococcus pneumoniae-induced interleukin (IL)-1ß release. The lack of IL-1ß resulted in the repression of bacterially induced granulocyte-macrophage colony-stimulating factor (GM-CSF) liberation. Specific inhibition of IFN receptor I and III-associated tyrosine kinase 2 (Tyk2) completely restored the S. pneumoniae-induced IL-1ß-GM-CSF axis, leading to a reduction of bacterial growth. A preceding IAV infection of the human alveolus leads to a type I and III IFN-dependent blockade of the early cytokines IL-1ß and GM-CSF, which are key for orchestrating an adequate innate immune response against bacteria. Their virally induced suppression may result in impaired bacterial clearance and alveolar repair.Pharmacological inhibition of Tyk2 might be a new treatment option to sustain beneficial endogenous GM-CSF levels in IAV-associated secondary bacterial pneumonia.

State of the art of robotic thymectomy.

BACKGROUND: Thymectomy is a widely accepted treatment for most cases of myasthenia gravis and essential for the treatment of thymoma. The development of a minimally invasive procedure for thymectomy resulted in a variety of approaches for surgery on the thymic gland. The use of thoracoscopy-based techniques has continued to increase, including the latest advance in this field, robotic thymectomy. METHODS: We review the rapid development and actual use of this approach by examining published reports, worldwide registries, and personal communications and by analyzing our database, which is the largest single-center experience and contains 317 thymectomies until 12/2012. The technical modifications of robotic thymectomy are also described. RESULTS: Since 2001, approximately 3,500 robotic thymectomies have been registered worldwide. Meanwhile, the results of approximately 500 thymectomy cases have been published. Robotic thymectomy is performed most frequently through a standardized unilateral three-trocar approach. All reports describe promising and satisfactory results for myasthenia gravis. For early-stage thymoma, robotic thymectomy is a technically sound and safe procedure with a very low complication rate and short hospital stay. Oncological outcome without recurrences is promising, but a longer follow-up is needed. CONCLUSION: The unilateral robotic technique can be considered an adequate approach for thymectomy, even with demanding anatomical configurations. Robotic thymectomy has spread worldwide over the last decade because of the promising results in myasthenia gravis and thymoma patients.

Influenza A viruses target type II pneumocytes in the human lung.

BACKGROUND: Highly pathogenic avian H5N1 influenza viruses preferentially infect alveolar type II pneumocytes in human lung. However, it is unknown whether this cellular tropism contributes to high viral virulence because the primary target cells of other influenza viruses have not been systematically studied. METHODS: We provide the first comparison of the replication, tropism, and cytokine induction of human, highly pathogenic avian influenza A virus subtype H5N1 and other animal influenza A viruses in primary human lung organ cultures. RESULTS: Subytpe H5N1 and human-adapted subtype H1N1 and H3N2 viruses replicated efficiently in the lung tissue, whereas classic swine and low-pathogenicity avian viruses propagated only poorly. Nevertheless, all viruses examined were detected almost exclusively in type II pneumocytes, with a minor involvement of alveolar macrophages. Infection with avian viruses that have a low and high pathogenicity provoked a pronounced induction of cytokines and chemokines, while human and pandemic H1N1-2009 viruses triggered only weak responses. CONCLUSIONS: These findings show that differences in the pathogenic potential of influenza A viruses in the human lung cannot be attributed to a distinct cellular tropism. Rather, high or low viral pathogenicity is associated with a strain-specific capacity to productively replicate in type II pneumocytes and to cope with the induced cytokine response.

Advanced lung cancer patient benefits from minimally invasive costal resection and reconstruction: an effective palliative approach for costal metastasis.

We hereby describe the resection and reconstruction of a rib infiltrated by a lung cancer metastasis. Despite prior radiation therapy aimed at mitigating pain from rib infiltration in a stage IV non-small cell lung cancer patient, results were unsatisfactory. Employing a minimally invasive palliative strategy, we executed a successful operation to address this issue. This technique presents a viable alternative for patients experiencing recurrent pain post radiation therapy.

Vascular clips versus ligatures in thyroid surgery--results of a multicenter randomized controlled trial (CLIVIT Trial).

BACKGROUND: New techniques using vascular clips or ultrasonically activated shears have been suggested to shorten operation time without compromising safety. The objective of the CLIVIT Trial was to compare ligatures with vascular clips for hemostasis in elective benign thyroid surgery. METHODS: This multicenter, randomized, controlled, parallel group superiority trial was conducted in 13 German surgical centers. Patients scheduled for at least subtotal resection bilaterally were intraoperatively randomized. The primary endpoint was resection time. Secondary endpoints were the amount of postoperative bleeding, reoperation due to bleeding, wound infection, temporary (reversal within 12 months) and permanent (over 1 year) recurrent laryngeal nerve (RLN) paralysis, length of hospital stay, and safety. REGISTRATION: ISRCTN 96901396. RESULTS: Two hundred fifty patients were treated with ligatures and 241 with vascular clips. No differences in patients' baseline and surgical characteristics were observed. No difference was detected for mean resection time (clip 63.5 min ± 29.6, ligature 66.1 min ± 29.3, P = 0.258). Postoperative bleeding (mean 86 ml ± 93), reoperation due to bleeding (clips 4, ligature 2), wound infections (clips 4, ligature 4), postoperative hospital stay (mean 3.0 ± 1.9), and safety data also did not vary significantly. The rates of temporary and permanent RLN paralysis were 6.9 % (34/491) and 2.9 % (14/491), respectively. Not using a surgical drain (123 patients) was not associated with a higher rate of complications. CONCLUSION: Vascular clips did not reduce the resection time. However, a 2.9 % rate of permanent RLN paralysis is of concern. Drains in elective surgery may be of no benefit.

Acute appendicitis is characterised by local invasion with Fusobacterium nucleatum/necrophorum.

BACKGROUND: Acute appendicitis is a local intestinal inflammation with unclear origin. The aim was to test whether bacteria in appendicitis differ in composition to bacteria found in caecal biopsies from healthy and disease controls. METHODS AND PATIENTS: We investigated sections of 70 appendices using rRNA-based fluorescence in situ hybridisation. Four hundred caecal biopsies and 400 faecal samples from patients with inflammatory bowel disease and other conditions were used as controls. A set of 73 group-specific bacterial probes was applied for the study. RESULTS: The mucosal surface in catarrhal appendicitis showed characteristic lesions of single epithelial cells filled with a mixed bacterial population ('pinned cells') without ulceration of the surroundings. Bacteria deeply infiltrated the tissue in suppurative appendicitis. Fusobacteria (mainly Fusobacterium nucleatum and necrophorum) were a specific component of these epithelial and submucosal infiltrates in 62% of patients with proven appendicitis. The presence of Fusobacteria in mucosal lesions correlated positively with the severity of the appendicitis and was completely absent in caecal biopsies from healthy and disease controls. Main faecal microbiota represented by Bacteroides, Eubacterium rectale (Clostridium group XIVa), Faecalibacterium prausnitzii groups and Akkermansia muciniphila were inversely related to the severity of the disease. The occurrence of other bacterial groups within mucosal lesions of acute appendicitis was not related to the severity of the appendicitis. No Fusobacteria were found in rectal swabs of patients with acute appendicitis. CONCLUSIONS: Local infection with Fusobacterium nucleatum/necrophorum is responsible for the majority of cases of acute appendicitis.

A predictive model of lymph node metastasis for thymic epithelial tumours.

OBJECTIVES: Thymic epithelial tumours (TETs) are relatively rare indolent malignancies in the mediastinum. Lymph node metastasis (LNM) is an important prognostic indicator for TETs; however, the pattern of LNM involved in TETs has yet to be elucidated. METHODS: Patients diagnosed with histologically confirmed thymoma (A-B3), thymic carcinomas and thymic neuroendocrine tumours, between 1988 and 2016 were identified from the Surveillance, Epidemiology, and End Results database. Univariable and multivariable logistic regression analyses were applied to identify the predictors for LNM. The predictive nomogram was built from the independent risk factors and measured using the concordance statistic. RESULTS: The overall proportion of TETs with LNM was 18.5% (200/1048). The rate of LNM in thymoma, thymic carcinomas and thymic neuroendocrine tumours was 6.8% (42/622), 30.2% (100/331) and 61.1% (58/95), respectively. According to the logistic regression analysis, histology type and T stage were independent factors correlated with LNM. A predictive nomogram model was developed with a concordance statistic of 0.807 (95% confidence interval: 0.773-0.841), which was significantly better than the T stage (P < 0.001) while had limited benefit to the histology type (P = 0.047). The calibration curve for the nomogram comparing the predicted and actual probabilities after bias correction showed good agreement. CONCLUSIONS: Nodal involvement was not uncommon in TETs. Main factors related to LNM in TETs were histology type and T stage. The probability of LNM could be well calculated using the predictive model.

Transcriptomic comparison of primary human lung cells with lung tissue samples and the human A549 lung cell line highlights cell type specific responses during infections with influenza A virus.

Influenza A virus (IAV) causes pandemics and annual epidemics of severe respiratory infections. A better understanding of the molecular regulation in tissue and cells upon IAV infection is needed to thoroughly understand pathogenesis. We analyzed IAV replication and gene expression induced by IAV strain H3N2 Panama in isolated primary human alveolar epithelial type II cells (AECIIs), the permanent A549 adenocarcinoma cell line, alveolar macrophages (AMs) and explanted human lung tissue by bulk RNA sequencing. Primary AECII exhibit in comparison to AM a broad set of strongly induced genes related to RIG-I and interferon (IFN) signaling. The response of AECII was partly mirrored in A549 cells. In human lung tissue, we observed induction of genes unlike in isolated cells. Viral RNA was used to correlate host cell gene expression changes with viral burden. While relative induction of key genes was similar, gene abundance was highest in AECII cells and AM, while weaker in the human lung (due to less IAV replication) and A549 cells (pointing to their limited suitability as a model). Correlation of host gene induction with viral burden allows a better understanding of the cell-type specific induction of pathways and a possible role of cellular crosstalk requiring intact tissue.

Human alveolar progenitors generate dual lineage bronchioalveolar organoids.

Mechanisms of epithelial renewal in the alveolar compartment remain incompletely understood. To this end, we aimed to characterize alveolar progenitors. Single-cell RNA-sequencing (scRNA-seq) analysis of the HTII-280+/EpCAM+ population from adult human lung revealed subclusters enriched for adult stem cell signature (ASCS) genes. We found that alveolar progenitors in organoid culture in vitro show phenotypic lineage plasticity as they can yield alveolar or bronchial cell-type progeny. The direction of the differentiation is dependent on the presence of the GSK-3ß inhibitor, CHIR99021. By RNA-seq profiling of GSK-3ß knockdown organoids we identified additional candidate target genes of the inhibitor, among others FOXM1 and EGF. This gives evidence of Wnt pathway independent regulatory mechanisms of alveolar specification. Following influenza A virus (IAV) infection organoids showed a similar response as lung tissue explants which confirms their suitability for studies of sequelae of pathogen-host interaction.

Effect of Lymph Node Dissection on the Prognosis of Thymic Carcinomas and Thymic Neuroendocrine Tumors.

We aimed to analyze the effect of lymph node dissection (LND) and accurate lymph node (LN) status on the survival and prognosis of patients with thymic carcinomas (TCs) and thymic neuroendocrine tumors (TNETs) undergoing surgical treatment. The Surveillance, Epidemiology, and End Results database was queried for patients who underwent surgical resection for TCs and TNETs during 1998-2016. LN status were defined as no LND (LND-), pathologically negative with LND (N0), and LN metastasis positive (N+). We investigated outcomes of LN status together with other clinicopathological features for overall survival (OS). Subgroup analyses were performed between LND-, N0, and N+ cohorts using propensity score matching, to analyze the significance of LND in prognosis. A total of 812 patients were enrolled, including 623 with TCs and 189 with TNETs. The proportion of LN metastasis positive in TNETs was 58.8% which was significantly higher than that in TCs (30%) (P < 0.001). In multivariable Cox analysis of OS, patients with LND- had a significantly worse prognosis than those with N0 (P = 0.018); there was no difference between N+ and LND- (P = 0.560). After propensity score matching, patients with N0 still had better survival than those with LND- and N+ in subgroup univariable and multivariable analyses of OS; however, the survival of patients with LND- and N+ was not significantly different in multivariable analysis. It was demonstrated that LND in TCs and TNETs can clarify the status of LN metastasis, to more accurately evaluate patients' long-term prognosis.

Minimally invasive thymectomy for myasthenia gravis favours left-sided approach and low severity class.

OBJECTIVES: Complete thymectomy is a key component of the optimal treatment for myasthenia gravis. Unilateral, minimally invasive approaches are increasingly utilized with debate about the optimal laterality approach. A right-sided approach has a wider field of view, while a left-sided approach accesses potentially more thymic tissue. We aimed to assess the impact of laterality on perioperative and medium-term outcomes, and to identify predictors of a 'good outcome' using standard definitions. METHODS: We performed a multicentre review of 123 patients who underwent a minimally invasive thymectomy for myasthenia gravis between January 2000 and August 2015, with at least 1-year follow-up. The Myasthenia Gravis Foundation of America standards were followed. A 'good outcome' was defined by complete stable remission/pharmacological remission/minimal manifestations 0, and a 'poor outcome' by minimal manifestations 1-3. Univariate and multivariable logistic regression analyses were performed to assess factors associated with a 'good outcome'. RESULTS: Ninety-two percent of thymectomies (113/123) were robotic-assisted. The left-sided approach had a shorter median operating time than a right-sided: 143 (interquartile range, IQR 110-196) vs 184 (IQR 133-228) min, P = 0.012. At a median of 44 (IQR 27-75) months, the left-sided approach achieved a 'good outcome' (46%, 31/68) more frequently than the right-sided (22%, 12/55); P = 0.011. Multivariable analysis identified a left-sided approach and Myasthenia Gravis Foundation of America class I/II to be associated with a 'good outcome'. CONCLUSIONS: A left-sided thymectomy may be preferred over a right-sided approach in patients with myasthenia gravis given the shorter operating times and potential for superior medium-term symptomatic outcomes. A lower severity class is also associated with a 'good outcome'.

Single lung resection: The limits of the possible. Clinical report.

INTRODUCTION: Single lung resection remains a challenge due to the preservation of the respiratory reserve. This report presents that case of a female patient with bilateral fibrotic-cavitary pulmonary tuberculosis complicated with empyema on the right lung. Only 3.5 lung segments were left after a multistage surgery. PRESENTATION OF CASE: The first stage included draining of empyema and transsternal transmediastinal right main bronchus occlusion. Then, upper lobectomy with partial S6 resection of the left lung, followed by pleuropneumonectomy was performed. At a follow-up of two years and 10 months, patient's condition was good. DISCUSSION: Although single lung surgery has been possible over half a century ago, it remains a high-risk intervention. CONCLUSION: With the removal of the non-functioning parenchyma and elimination of the air/vascular shunt, single lung resection volume exceeding lobectomy is possible, which may improve cardiorespiratory function.

Thymectomy in ocular myasthenia gravis before generalization results in a higher remission rate.

OBJECTIVES: This study aimed to compare the outcomes of patients with ocular myasthenia gravis (OMG) who underwent thymectomy before generalization with the outcomes of those who underwent thymectomy after generalization. METHODS: We retrospectively reviewed patients who underwent robotic thymectomy for myasthenia gravis between January 2003 and February 2018. Patients who presented with purely ocular symptoms at myasthenia gravis onset were eligible for inclusion. Exclusion criteria were patients who were lost to follow-up and patients who underwent re-thymectomy. Patients with OMG who developed generalization before thymectomy were categorized into gOMG group and those who did not were categorized into OMG group. The primary outcome was complete stable remission according to the Myasthenia Gravis Foundation of America Post-Intervention Status (MGFA-PIS). RESULTS: One hundred and sixty-five (66 males and 99 females) out of 596 patients with myasthenia gravis were eligible for inclusion. Of these, there were 73 and 92 patients undergoing thymectomy before and after the generalization of OMG, respectively. After propensity score matching, a data set of 130 patients (65 per group) was formed and evaluating results showed no statistical differences between the 2 groups. The estimated cumulative probabilities of complete stable remission at 5 years were 49.5% [95% confidence interval (CI) 0.345-0.611] in the OMG group and 33.4% (95% CI 0.176-0.462) in the gOMG group (P = 0.0053). Similar results were also found in patients with non-thymomatous subgroup [55 patients per group, OMG vs gOMG, 53.5% (95% CI 0.370-0.656) vs 28.9% (95% CI 0.131-0.419), P = 0.0041]. CONCLUSIONS: Thymectomy in OMG before generalization might result in a higher rate of complete stable remission than thymectomy after generalization.

Current status and evolution of robotic-assisted thoracic surgery in Germany-results from a nationwide survey.

BACKGROUND: Robot-assisted surgery has made a significant entry into surgical practice within Germany, including thoracic surgery. As no published data exists regarding robotic-assisted thoracic surgery (RATS), we conducted a survey to investigate its current status. METHODS: We performed a nationwide survey of all centers active in RATS, using a standardized questionnaire. The annual number of operations, mean duration of surgery, docking time, length of hospital stay(s), conversions, chest tube duration, the RATS program start date, robot system used, operating room capacity, and staplers and instruments used were recorded. RESULTS: Of the 22 centers contacted, 14 responded. In total, 786 RATS interventions were recorded. Most were anatomical lung resections, comprising 372 (bi-) lobectomies and 80 segmentectomies. During the study period, eight bronchoplastic procedures were performed robotically. There were 93 wedge lung resections, 148 thymectomies, 26 sympathectomies, and 59 other RATS procedures, and a single-center series of around 1,000 RATS thymectomies (excluded from statistical analysis). The average incision-suture time of the RATS lobectomy was 245 (range, 80-419) minutes, average residence time seven days. The conversion rate was 6.7% across all interventions, with significant inter-intervention differences. All surveyed centers plan to further expand RATS, with OR capacity being a frequent impediment. Five RATS interventions were performed in Germany in 2013, versus 320 in 2018. CONCLUSIONS: Overall, RATS is becoming more established in everyday clinical practice in Germany. The number of operations, active centers, and trained RATS surgeons has increased steadily since 2013. A German-speaking operation course for entry into RATS already exists. Even extended resections can be carried out safely, and RATS has become standard procedure in some centers.

Unraveling the role of ectopic thymic tissue in patients undergoing thymectomy for myasthenia gravis.

Extended thymectomy has been considered the goal of surgery for myasthenia gravis (MG) mainly due to the existence of ectopic thymic tissue. Recently, ectopic thymic tissue has attracted increasing attention in patients with MG following thymectomy. However, the specific role of ectopic thymic tissue in patients with MG is still under debate. A systematic search of the literature was performed on PubMed and Medline according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISM) statement. Studies evaluating the rate of ectopic thymic tissue in patients with MG with or without thymoma were included. Extraction was performed for all eligible studies and the rate of ectopic thymic tissue at common locations was calculated. Eighteen out of fifty-nine studies were eligible for inclusion, of which ten studies reported the common locations of ectopic thymic tissue in mediastinal fat. Of these ten studies, the presence of ectopic thymic tissue was investigated in different anatomical locations in 882 patients, of whom, 509 patients (58%) have at least one positive location with the most common ones being anterior mediastinal fat, pericardiophrenic angles, aortopulmonary window, cervical region (pretracheal fat) and lateral to phrenic nerves. On the other hand, nine studies analyzed the influence of the presence of ectopic thymic tissue on the clinical outcomes of MG patients. Of these, six found that the presence of ectopic thymic tissue in MG patients is a significant predictor of poor outcome after thymectomy, however, the other three did not find a significance. Altogether, ectopic thymic tissue is likely to present in more than a half of patients undergoing thymectomy for MG. Besides, MG patients who have ectopic thymic tissue after thymectomy do not seem to have as good outcome as those who have not.