SARS-CoV-2 Omicron variant replication in human bronchus and lung ex vivo.

The emergence of SARS-CoV-2 variants of concern with progressively increased transmissibility between humans is a threat to global public health. The Omicron variant of SARS-CoV-2 also evades immunity from natural infection or vaccines1, but it is unclear whether its exceptional transmissibility is due to immune evasion or intrinsic virological properties. Here we compared the replication competence and cellular tropism of the wild-type virus and the D614G, Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2) and Omicron (B.1.1.529) variants in ex vivo explant cultures of human bronchi and lungs. We also evaluated the dependence on TMPRSS2 and cathepsins for infection. We show that Omicron replicates faster than all other SARS-CoV-2 variants studied in the bronchi but less efficiently in the lung parenchyma. All variants of concern have similar cellular tropism compared to the wild type. Omicron is more dependent on cathepsins than the other variants of concern tested, suggesting that the Omicron variant enters cells through a different route compared with the other variants. The lower replication competence of Omicron in the human lungs may explain the reduced severity of Omicron that is now being reported in epidemiological studies, although determinants of severity are multifactorial. These findings provide important biological correlates to previous epidemiological observations.

Information-Distilled Generative Label-Free Morphological Profiling Encodes Cellular Heterogeneity.

Image-based cytometry faces challenges due to technical variations arising from different experimental batches and conditions, such as differences in instrument configurations or image acquisition protocols, impeding genuine biological interpretation of cell morphology. Existing solutions, often necessitating extensive pre-existing data knowledge or control samples across batches, have proved limited, especially with complex cell image data. To overcome this, "Cyto-Morphology Adversarial Distillation" (CytoMAD), a self-supervised multi-task learning strategy that distills biologically relevant cellular morphological information from batch variations, is introduced to enable integrated analysis across multiple data batches without complex data assumptions or extensive manual annotation. Unique to CytoMAD is its "morphology distillation", symbiotically paired with deep-learning image-contrast translation-offering additional interpretable insights into label-free cell morphology. The versatile efficacy of CytoMAD is demonstrated in augmenting the power of biophysical imaging cytometry. It allows integrated label-free classification of human lung cancer cell types and accurately recapitulates their progressive drug responses, even when trained without the drug concentration information. CytoMAD  also allows joint analysis of tumor biophysical cellular heterogeneity, linked to epithelial-mesenchymal plasticity, that standard fluorescence markers overlook. CytoMAD can substantiate the wide adoption of biophysical cytometry for cost-effective diagnosis and screening.

High-Throughput, Label-Free and Slide-Free Histological Imaging by Computational Microscopy and Unsupervised Learning.

Rapid and high-resolution histological imaging with minimal tissue preparation has long been a challenging and yet captivating medical pursuit. Here, the authors propose a promising and transformative histological imaging method, termed computational high-throughput autofluorescence microscopy by pattern illumination (CHAMP). With the assistance of computational microscopy, CHAMP enables high-throughput and label-free imaging of thick and unprocessed tissues with large surface irregularity at an acquisition speed of 10 mm2 /10 s with 1.1-µm lateral resolution. Moreover, the CHAMP image can be transformed into a virtually stained histological image (Deep-CHAMP) through unsupervised learning within 15 s, where significant cellular features are quantitatively extracted with high accuracy. The versatility of CHAMP is experimentally demonstrated using mouse brain/kidney and human lung tissues prepared with various clinical protocols, which enables a rapid and accurate intraoperative/postoperative pathological examination without tissue processing or staining, demonstrating its great potential as an assistive imaging platform for surgeons and pathologists to provide optimal adjuvant treatment.

Replication of SARS-CoV-2 Omicron BA.2 variant in ex vivo cultures of the human upper and lower respiratory tract.

BACKGROUND: The Omicron BA.2 sublineage has replaced BA.1 worldwide and has comparable levels of immune evasion to BA.1. These observations suggest that the increased transmissibility of BA.2 cannot be explained by the antibody evasion. METHODS: Here, we characterized the replication competence and respiratory tissue tropism of three Omicron variants (BA.1, BA.1.1, BA.2), and compared these with the wild-type virus and Delta variant, in human nasal, bronchial and lung tissues cultured ex vivo. FINDINGS: BA.2 replicated more efficiently in nasal and bronchial tissues at 33°C than wild-type, Delta and BA.1. Both BA.2 and BA.1 had higher replication competence than wild-type and Delta viruses in bronchial tissues at 37°C. BA.1, BA.1.1 and BA.2 replicated at a lower level in lung parenchymal tissues compared to wild-type and Delta viruses. INTERPRETATION: Higher replication competence of Omicron BA.2 in the human upper airway at 33°C than BA.1 may be one of the reasons to explain the current advantage of BA.2 over BA.1. A lower replication level of the tested Omicron variants in human lung tissues is in line with the clinical manifestations of decreased disease severity of patients infected with the Omicron strains compared with other ancestral strains. FUNDING: This work was supported by US National Institute of Allergy and Infectious Diseases and the Theme-Based Research Scheme under University Grants Committee of Hong Kong Special Administrative Region, China.

Thromboxane synthase suppression induces lung cancer cell apoptosis via inhibiting NF-κB.

Accumulating evidence shows that the inhibition of thromboxane synthase (TXS) induced apoptosis in cancer cells. TXS inhibitor 1-Benzylimidzole (1-BI) can trigger apoptosis in lung cancer cells but the mechanism is not fully defined. In this study, lung cancer cells were treated with 1-BI. In this study, the level of reactive oxygen species (ROS) was measured and NF-κB activity was determined in human lung cancer cells. The roles of ROS and NF-κB in 1-BI-mediated cell death were analyzed. The results showed that 1-BI induced ROS generation but decreased the activity of NF-κB by reducing phosphorylated IκBα (p-IκBα) and inhibiting the translocation of p65 into the nucleus. In contrast to 1-BI, antioxidant N-acetyl cysteine (NAC) stimulated cell proliferation and significantly protected the cells from 1-BI-mediated cell death by neutralizing ROS. Collectively, apoptosis induced by 1-BI is associated with the over-production of ROS and the reduction of NF-κB. Antioxidants can significantly block the inhibitory effect of 1-BI.

Spontaneous haemopneumothorax: current management.

Spontaneous haemopneumothorax (SHP) can be life threatening and is an important cause for unexplained signs of significant hypovolaemia. There is still some debate relating to patient selection and timing of surgery, particularly in those who become stable following chest tube insertion without further blood loss. Review of the literature over the past decade in the management of SHP are presented and discussed. Surgery should be considered early in the management of SHP to reduce morbidity associated with continued haemorrhage and inadequate drainage. Lower postoperative complications and shorter hospital stay following video assisted thoracic surgery compared with thoracotomy have led to its increased acceptance as an alternative approach for SHP patients who are haemodynamically stable.

PPARgamma activation extinguishes smoking carcinogen by inhibiting NNK-mediated proliferation.

Among the carcinogenic chemicals of cigarette smoking, 4-(methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) is the most potent. The activation of peroxisome proliferator-activated receptor (PPAR)gamma can arrest the growth of lung cancer. We hypothesized that PPARgamma activation inhibits NNK-mediated proliferation of lung cancer cells. PPARgamma expression was increased in 94.7% human lung cancer tumor tissues, compared with their paired corresponding nontumor tissues. PPARgamma was also found to be abundant in all the lung cancer cell lines tested. Troglitazone dose-dependently inhibited the NNK-mediated proliferation of lung cancer cells that expressed PPARgamma. Troglitazone blocked NNK-induced up-regulation of HO-1, Bcl-2, and c-IAP2, and recovered Bad activity that was suppressed by NNK. NNK promoted the nuclear p21, whereas troglitazone increased cytosolic p21. Troglitazone increased PPARgamma transcriptional activity in NNK-treated cells and a PPARgamma dominant-negative inhibitor completely suppressed the action of troglitazone, indicating that troglitazone against NNK was PPARgamma-dependent. The findings reveal a novel molecular pathway of PPARgamma activation against cigarette smoking-related lung cancer.

Roles of peroxisome proliferator-activated receptor-alpha and -gamma in the development of non-small cell lung cancer.

Peroxisome proliferator-activated receptor (PPAR)-α and PPARγ participate in cell proliferation and apoptosis. Few studies have simultaneously investigated both PPARα and PPARγ in lung cancers in vivo. The roles of PPARα and -γ were investigated in the development of pulmonary tumors induced in the adult A/J mouse by treatment with 4-(methylnitrosamino)-l-(3-pyridyl)-lbutanone (NNK). Compared with the normal lung tissues, PPARγ expression was much higher in the NNK-induced lung tumor tissues. However, PPARγ transcriptional activity, and the levels of two major endogenous PPARγ ligands, 13-hydroxyoctadecadienoic acid and 15-hydroxyeicosatetraenoic acid, were significantly lower in the NNK-treated lung tissues. The ligand changes in mice were confirmed in human lung cancer tissues. Along with the alteration of PPARγ and its endogenous ligands, the level of PPARα and its activity were increased in the NNK-induced mouse lung tumors. Treatment of mice with the synthetic PPARγ ligand, pioglitazone, significantly inhibited the formation of mouse lung tumors induced by NNK. Our study demonstrated that the reduction of endogenous PPARγ ligands and increased PPARα occurred before the formation of lung tumors, indicating that the molecular changes play a role in lung carcinogenesis. The results suggest that the enhancement of PPARγ activity with its ligands, and the suppression of PPARα with its inhibitors, may prevent the formation of lung tumors, as well as accelerate the therapy of lung cancer. Our findings may also reveal the possibility of using the level of endogenous PPARγ ligands and the activities of PPARγ or PPARα as tumor markers for lung cancer.

15-Lipoxygenases and its metabolites 15(S)-HETE and 13(S)-HODE in the development of non-small cell lung cancer.

BACKGROUND: 15-S-Hydroxyeicosatetraenoic acid (15(S)-HETE) and 13-S-hydroxyoctadecadienoic acid (13(S)-HODE), both of which are metabolites of 15-lipoxygenases (15-LOXs), are endogenous ligands for peroxisome proliferator-activated receptor gamma (PPARgamma). The activation of PPARgamma inhibits cell growth and induces apoptosis in some cancers. The role of 15(S)-HETE) and 13(S)-HODE in the development of lung cancer is not clear. METHODS: 15-LOXs, 15(S)-HETE and 13(S)-HODE were monitored during the development of mouse lung tumours induced by the tobacco smoke carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and the levels of these markers were determined in 54 human non-small cell lung cancers. RESULTS: 15-LOXs, 15(S)-HETE and 13(S)-HODE levels were significantly reduced in human lung cancer tissue compared with non-tumour lung tissue (p=0.011 and p=0.022, respectively). In mouse experiments, 15(S)-HETE and 13(S)-HODE started to reduce at 26 and 30 weeks, respectively, after NNK treatment. The time frame of 15(S)-HETE reduction was in line with the decrease in 12/15-LOX mRNA and protein. A significant difference in the number of tumours in NNK-treated mice and controls was not observed until week 34 (p<0.05) and week 38 (p<0.01). The reduction in 12/15-LOX and 15(S)-HETE therefore predated the appearance of lung tumour. Furthermore, PPARgamma activity was decreased in NNK-treated mouse lungs compared with the control, and the decreased PPARgamma activity occurred at the same time points as the reduction in 12/15-LOX and 15(S)-HETE. CONCLUSION: These findings indicate that the reduction in 15-LOX, 15(S)-HETE and 13(S)-HODE results in the decreased PPARgamma activity seen in lung tumours and contributes to the development of lung tumours induced by tobacco smoking.

Inhibition of thromboxane synthase induces lung cancer cell death via increasing the nuclear p27.

The role of thromboxane in lung carcinogenesis is not clearly known, though thromboxane B2 (TXB(2)) level is increased and antagonists of thromboxane receptors or TXA2 can induce apoptosis of lung cancer cells. p27, an atypical tumor suppressor, is normally sequestered in the nucleus. The increased nuclear p27 may result in apoptosis of tumor cells. We hypothesize that the inhibition of thromboxane synthase (TXS) induces the death of lung cancer cells and that such inhibition is associated with the nuclear p27 level. Our experiment showed that the inhibition of TXS significantly induced the death or apoptosis in lung cancer cells. The activity of TXS was increased in lung cancer. The nuclear p27 was remarkably reduced in lung cancer tissues. The inhibition of TXS caused the cell death and apoptosis of lung cancer cells, likely via the elevation of the nuclear p27 since the TXS inhibition promoted the nuclear p27 level and the inhibition of p27 by its siRNA recovered the cell death induced by TXS inhibition. Collectively, lung cancer cells produce high levels of TXB(2) but their nuclear p27 is markedly reduced. The inhibition of TXS results in the p27-related induction of cell death in lung cancer cells.

Management of complications of minimally invasive thoracic surgery.

Minimally invasive thoracic surgery (MITS) has become part of the modern thoracic surgeon's armamentarium. Its applications include diagnostic and therapeutic procedures, and over the past one and a half decades, the scope of MITS has undergone rapid evolution. The role of MITS is well established in the management of pleural and mediastinal conditions, and it is beginning to move beyond diagnostic procedures for lung parenchyma conditions, to gain acceptance as a viable option for primary lung cancer treatment. However MITS poses technical challenges that are quite different from the conventional open surgical procedures. After a brief review of the history of MITS, an overview of the scope of MITS is given. Important examples of diagnostic and therapeutic indications are then discussed, with special emphasis on the potential complications specific to MITS, and their prevention and management.

Recent advances in video-assisted thoracoscopic approach to posterior mediastinal tumours.

Minimal invasive video-assisted thoracic surgery can be a safe alternative technique in the assessment, diagnosis and surgical resection of posterior mediastinal tumours. Video-assisted thoracic surgery may be particularly suited for the management of posterior mediastinal tumours as most are benign. Surgical technique continues to evolve from the classic 3-port access in order to tackle more complex tumours positioned at the apical and inferior recesses of the posterior mediastinum. The preoperative identification of dumbbell tumours is important to facilitate arrangements for a single-stage combined resection for both the intra-thoracic and intraspinal tumour. Results from Video-assisted thoracic surgery posterior mediastinal tumour resection are comparable with conventional surgical techniques in terms of symptomatic improvement, recurrence and survival. Video-assisted thoracic surgery approach has been shown to result in less post-operative pain, improved cosmesis, shorter hospital stay, and more rapid recovery and return to normal activities. In over a decade, video-assisted thoracic surgery has gradually matured and is now a promising therapeutic alternative to open approach. In certain selected patients, video-assisted thoracic surgery may be considered the standard of care for conditions of the posterior mediastinum. Recent developments in robotic surgery for the management of mediastinal tumours are promising, however, long-term results are pending.

Deep-learning-assisted biophysical imaging cytometry at massive throughput delineates cell population heterogeneity.

The association of the intrinsic optical and biophysical properties of cells to homeostasis and pathogenesis has long been acknowledged. Defining these label-free cellular features obviates the need for costly and time-consuming labelling protocols that perturb the living cells. However, wide-ranging applicability of such label-free cell-based assays requires sufficient throughput, statistical power and sensitivity that are unattainable with current technologies. To close this gap, we present a large-scale, integrative imaging flow cytometry platform and strategy that allows hierarchical analysis of intrinsic morphological descriptors of single-cell optical and mass density within a population of millions of cells. The optofluidic cytometry system also enables the synchronous single-cell acquisition of and correlation with fluorescently labeled biochemical markers. Combined with deep neural network and transfer learning, this massive single-cell profiling strategy demonstrates the label-free power to delineate the biophysical signatures of the cancer subtypes, to detect rare populations of cells in the heterogeneous samples (10-5), and to assess the efficacy of targeted therapeutics. This technique could spearhead the development of optofluidic imaging cell-based assays that stratify the underlying physiological and pathological processes based on the information-rich biophysical cellular phenotypes.

Dysfunction of pulmonary vascular endothelium in chronic obstructive pulmonary disease: basic considerations for future drug development.

Chronic obstructive pulmonary disease (COPD) is one of the leading health problems worldwide and continues to be a major cause of morbidity and mortality in developed countries. The clinical features of COPD are chronic obstructive bronchiolitis and emphysema. Pulmonary vascular endothelial dysfunction is a characteristic pathological finding of COPD at different stages of the disease. Functional changes of pulmonary endothelial cells in COPD include antiplatelet abnormalities, anticoagulant disturbances, endothelial activation, atherogenesis, and compromised regulation of vascular tone which may adversely affect the ventilation-perfusion match in COPD. As the most important risk factor of COPD, cigarette smoking may initiate pulmonary vascular impairment through direct injury of endothelial cells or release of inflammatory mediators. Morphological changes such as denudation of endothelium and endothelial cell apoptosis have been observed in the pulmonary vasculature in COPD patients as well as functional alterations. Changes in the expression of tissue factor pathway inhibitor (TFPI), thrombomodulin, selectins, and adhesion molecules in pulmonary endothelial cells as well as complex regulation and interaction of vasoactive substances and growth factors released from endothelium may underlie the mechanisms of pulmonary endothelial dysfunction in COPD. The mechanism of endothelial repair/regeneration in COPD, although not fully understood, may involve upregulation of vascular endothelial growth factors in the early stages along with an increased number of bone marrow-derived progenitor cells. These factors should be taken into account when developing new strategies for the pharmacological therapy of patients with COPD.

The history of lung transplantation in Hong Kong.

Clinical lung transplant was first performed in Hong Kong in 1995. In the early years, the volume of activity was very low. There has been a clear trend of increasing volume in the past few years. The recipient pathology is very different from the International Society for Heart and Lung Transplantation (ISHLT) database, with complete absence of cystic fibrosis and alpha-1-antitrypsin deficiency, and a predominance of diseases of the pulmonary circulation. Lymphangioleiomyomatosis (LAM) has a much higher representation on the waiting list than the ISHLT. The survival of patients who received a lung transplant in Hong Kong compares favorably with international data.