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Diagnosing and monitoring pulmonary diseases is highly dependent on imaging, physiological function tests and tissue sampling. Optical coherence tomography (OCT) and confocal laser endomicroscopy (CLE) are novel imaging techniques with near-microscopic resolution that can be easily and safely combined with conventional bronchoscopy. Disease-related pulmonary anatomical compartments can be visualized, real time, using these techniques. In obstructive lung diseases, airway wall layers and related structural remodelling can be identified and quantified. In malignant lung disease, normal and malignant areas of the central airways, lung parenchyma, lymph nodes and pleura can be discriminated. A growing number of interstitial lung diseases (ILDs) have been visualized using OCT or CLE. Several ILD-associated structural changes can be imaged: fibrosis, cellular infiltration, bronchi(ol)ectasis, cysts and microscopic honeycombing. Although not yet implemented in clinical practice, OCT and CLE have the potential to improve detection and monitoring pulmonary diseases and can contribute in unravelling the pathophysiology of disease and mechanism of action of novel treatments. Indeed, assessment of the airway wall layers with OCT might be helpful when evaluating treatments targeting airway remodelling. By visualizing individual malignant cells, CLE has the potential as a real-time lung cancer detection tool. In the future, both techniques could be combined with laser-enhanced fluorescent-labelled tracer detection. This review discusses the value of OCT and CLE in pulmonary medicine by summarizing the current evidence and elaborating on future perspectives.

Abstract Bronchoalveolar lavage (BAL) is a non-invasive bronchoscopic technique used to aspirate cells from the pulmonary interstitium, initially applied to detect neoplastic cells but later expanded for microbiological studies, leukocyte counts, molecular analyses, and immunophenotyping. This broader approach has linked BAL to the study of interstitial lung diseases (ILD). Despite its use since the 1970s, standardization of BAL cytopathological analysis is lacking, hindering its routine clinical application. The limited number of studies, particularly in Southern Hemisphere countries, reflects challenges in refining laboratory procedures and cytological findings. This article discusses the diagnostic potential of BAL when combined with clinical and radiological data. Integrating cytomorphologic findings with molecular techniques enhances its accuracy, particularly for cases with undefined etiopathogenesis, offering improved diagnostic and follow-up capabilities. The results make it clear that BALF cytology helps tell the difference between different types of ILDs. They also show that it is a useful tool for monitoring and diagnosing lung diseases. Resumo A lavagem broncoalveolar (LBA) é uma técnica broncoscópica não invasiva usada para aspirar células do interstício pulmonar. Inicialmente aplicada para detectar células neoplásicas, sua utilização foi ampliada para estudos microbiológicos, contagem de leucócitos, análises moleculares e imunofenotipagem. Essa abordagem mais ampla vinculou o LBA ao estudo de doenças pulmonares intersticiais (DIP). Apesar de ser utilizada desde a década de 1970, a análise citopatológica do LBA carece de padronização, dificultando sua aplicação como rotina clínica. A escassez de estudos, especialmente em países do hemisfério sul, reflete os desafios na melhoria dos procedimentos laboratoriais e dos achados citológicos. O artigo discute o potencial diagnóstico do LBA quando combinado com dados clínicos e radiológicos e os reune aos achados citomorfológicos com técnicas moleculares, visando proporcionar melhores capacidades de diagnóstico e acompanhamento. Os achados enfatizam que a citologia oriunda do LBA contribui com o diagnóstico diferencial de diversos subtipos de DIPs, sugerindo um algoritmo celular de fácil uso clínico, além de realçar sua versatilidade como ferramenta de acompanhamento e diagnóstico na área pneumológica.

Background Fibroblastic foci profusion on histopathology and severity of traction bronchiectasis on highresolution computed tomography (HRCT) have been shown to be predictors of mortality in patients with idiopathic pulmonary fibrosis (IPF). The aim of this study was to investigate the relationship between fibroblastic foci (FF) profusion and HRCT patterns in patients with a histopathologic diagnosis of usual interstitial pneumonia (UIP), fibrotic non-specific interstitial pneumonia (NSIP) and chronic hypersensitivity pneumonitis (CHP). Methods The HRCT scans of 162 patients with a histopathologic diagnosis of UIP or fibrotic NSIP (n = 162) were scored on extent of groundglass opacification, reticulation, honeycombing, emphysema and severity of traction bronchiectasis. For each patient, a fibroblastic foci profusion score based on histopathologic appearances was assigned. Relationships between extent of fibroblastic foci and individual HRCT patterns were investigated using univariate correlation analysis and multivariate linear regression. Results Increasing extent of reticulation ( P  < 0.0001) and increasing severity of traction bronchiectasis ( P  < 0.0001) were independently associated with increasing FF score within the entire cohort. Within individual multidisciplinary team diagnosis subgroups, the only significant independent association with FF score was severity of traction bronchiectasis in patients with idiopathic pulmonary fibrosis (IPF)/UIP (n = 66, r 2  = 0.19, P  < 0.0001) and patients with chronic hypersensitivity pneumonitis (CHP) (n = 49, r 2  = 0.45, P  < 0.0001). Furthermore, FF score had the strongest association with severity of traction bronchiectasis in patients with IPF (r 2  = 0.34, P  < 0.0001) and CHP (r 2  = 0.35, P  < 0.0001). There was no correlation between FF score and severity of traction bronchiectasis in patients with fibrotic NSIP. Global disease extent had the strongest association with severity of traction bronchiectasis in patients with fibrotic NSIP (r 2  = 0.58, P  < 0.0001). Conclusion In patients with fibrotic lung disease, profusion of fibroblastic foci is strikingly related to the severity of traction bronchiectasis, particularly in IPF and CHP. This may explain the growing evidence that traction bronchiectasis is a predictor of mortality in several fibrotic lung diseases.

Entirely re-written and revised with over 1,000 new images, Pulmonary Pathology: An Atlas and Text is a comprehensive, highly illustrated guide to diagnoses in pulmonary pathology, including tumors and lymphomas. The book-titled Color Atlas and Text of Pulmonary Pathology in earlier editions-combines highly detailed photographs and illustrations with concise, bulleted text so you can quickly grasp the information you need to make accurate diagnoses.

The binding of the receptor for advanced glycation end products (RAGE) with its ligands begins a sustained period of cellular activation and inflammatory signal amplification in different tissues and diseases. This binding could represent an as yet uninvestigated pathway of inflammatory reaction in the lung, where the presence of the receptor has been largely documented and advanced glycation end products (AGEs) are produced by nonenzymatic glycation and oxidation of proteins and lipids, driven by smoke and pollutants exposure or inflammatory stress. We immunohistochemically assessed the expression of RAGE and of its major proinflammatory ligands, N-ɛ-carboxy-methyl-lysine, S100B and S-100A12 in normal lung and in non-neoplastic lung disorders including smoke-related airway disease, granulomatous inflammation, postobstructive damage and usual interstitial pneumonia. In normal lung low expression of the receptor was observed in bronchiolar epithelia, type II pneumocytes, macrophages and some endothelia. S100A12 and S100B were expressed, respectively, in granulocytes and in dendritic cells. Carboxy-methyl-lysine was present in bronchiolar epithelia and macrophages. In all pathological conditions associated with inflammation and lung damage overexpression of both the receptor and of AGEs was observed in bronchiolar epithelia, type II alveolar pneumocytes, alveolar macrophages and endothelia. RAGE overexpression was more evident in epithelia associated with inflammatory cell aggregates. Fibroblasts in usual interstitial pneumonia expressed both the receptor and AGEs. The number of S100A12 and S100B immunoreactive inflammatory cells was variable. S100A12 was also expressed in mononuclear inflammatory cells and in activated epithelia. The activation of the inflammatory pathway controlled by the RAGE is not specific of a single lung disease, however, it may be relevant as a nonspecific pathway of sustained inflammation in lung tissue, and on this basis therapeutic approaches based on receptor blockage can be envisaged.

Since its initial recognition in December 2019, Coronavirus disease 19 (COVID-19) has quickly spread to a pandemic infectious disease. The causative agent has been recognized as a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), primarily affecting the respiratory tract. To date, no vaccines are available nor any specific treatment. To limit the number of infections, strict directives have been issued by governments that have been translated into equally rigorous guidelines notably for post-mortem examinations by international and national scientific societies. The recommendations for biosafety control required during specimen collection and handling have strongly limited the practice of autopsies of the COVID-19 patients to a few adequate laboratories. A full pathological examination has always been considered an important tool to better understand the pathophysiology of diseases, especially when the knowledge of an emerging disorder is limited and the impact on the healthcare system is significant. The first evidence of diffuse alveolar damage in the context of an acute respiratory distress syndrome has now been joined by the latest findings that report a more complex scenario in COVID-19, including a vascular involvement and a wide spectrum of associated pathologies. Ancillary tools such as electron microscopy and molecular biology used on autoptic tissue samples from autopsy are also significantly contributing to confirm and/or identify new aspects useful for a deeper knowledge of the pathogenetic mechanisms. This article will review and summarize the pathological findings described in COVID-19 until now, chiefly focusing on the respiratory tract, highlighting the importance of autopsy towards a better knowledge of this disease.

AimsPulmonary toxoplasmosis has become a very rare parasitic infection since the advent of highly active antiretroviral therapies. It is generally diagnosed by the direct microscopic observation of Toxoplasma gondii tachyzoites in bronchoalveolar lavage fluid (BALF). The aim of this study was to assess possible improvements in diagnostic performance associated with the use of real-time PCR.MethodsThis prospective study was carried out on BALFs obtained from immunocompromised patients over a 2-year period. We systematically compared the results of conventional staining with those of molecular detection.ResultsTwo cases of pulmonary toxoplasmosis were diagnosed for a total of 336 samples. PCR did not detect any additional cases and was more time-consuming than conventional staining.ConclusionsConventional staining is a reliable technique and is probably the most appropriate method for experienced microbiology laboratories, whereas T. gondii-specific PCR may be useful for laboratories with less experience in parasitology.Trial registration number2015_030, May 27th 2015.

Transforming growth factor (TGF)-β is an evolutionarily conserved pleiotropic factor that regulates a myriad of biological processes including development, tissue regeneration, immune responses, and tumorigenesis. TGF-β is necessary for lung organogenesis and homeostasis as evidenced by genetically engineered mouse models. TGF-β is crucial for epithelial-mesenchymal interactions during lung branching morphogenesis and alveolarization. Expression and activation of the three TGF-β ligand isoforms in the lungs are temporally and spatially regulated by multiple mechanisms. The lungs are structurally exposed to extrinsic stimuli and pathogens, and are susceptible to inflammation, allergic reactions, and carcinogenesis. Upregulation of TGF-β ligands is observed in major pulmonary diseases, including pulmonary fibrosis, emphysema, bronchial asthma, and lung cancer. TGF-β regulates multiple cellular processes such as growth suppression of epithelial cells, alveolar epithelial cell differentiation, fibroblast activation, and extracellular matrix organization. These effects are closely associated with tissue remodeling in pulmonary fibrosis and emphysema. TGF-β is also central to T cell homeostasis and is deeply involved in asthmatic airway inflammation. TGF-β is the most potent inducer of epithelial-mesenchymal transition in non-small cell lung cancer cells and is pivotal to the development of tumor-promoting microenvironment in the lung cancer tissue. This review summarizes and integrates the current knowledge of TGF-β signaling relevant to lung health and disease.

The ongoing coronavirus disease 2019 (COVID-19) pandemic is associated with substantial morbidity and mortality. Although much has been learned in the first few months of the pandemic, many features of COVID-19 pathogenesis remain to be determined. For example, anosmia is a common presentation, and many patients with anosmia show no or only minor respiratory symptoms 1 . Studies in animals infected experimentally with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of COVID-19, provide opportunities to study aspects of the disease that are not easily investigated in human patients. Although the severity of COVID-19 ranges from asymptomatic to lethal 2 , most experimental infections provide insights into mild disease 3 . Here, using K18-hACE2 transgenic mice that were originally developed for SARS studies 4 , we show that infection with SARS-CoV-2 causes severe disease in the lung and, in some mice, the brain. Evidence of thrombosis and vasculitis was detected in mice with severe pneumonia. Furthermore, we show that infusion of convalescent plasma from a recovered patient with COVID-19 protected against lethal disease. Mice developed anosmia at early time points after infection. Notably, although pre-treatment with convalescent plasma prevented most signs of clinical disease, it did not prevent anosmia. Thus, K18-hACE2 mice provide a useful model for studying the pathological basis of both mild and lethal COVID-19 and for assessing therapeutic interventions. Transgenic K18-hACE2 mice are a useful model of COVID-19 including anosmia; infection of these mice resulted in severe pneumonia and, in some cases, infection in the brain, which was prevented by convalescent plasma.

Brucella are facultative intracellular bacteria that chronically infect humans and animals causing brucellosis. Brucella are able to invade and replicate in a broad range of cell lines in vitro, however the cells supporting bacterial growth in vivo are largely unknown. In order to identify these, we used a Brucella melitensis strain stably expressing mCherry fluorescent protein to determine the phenotype of infected cells in spleen and liver, two major sites of B. melitensis growth in mice. In both tissues, the majority of primary infected cells expressed the F4/80 myeloid marker. The peak of infection correlated with granuloma development. These structures were mainly composed of CD11b⁺ F4/80⁺ MHC-II⁺ cells expressing iNOS/NOS2 enzyme. A fraction of these cells also expressed CD11c marker and appeared similar to inflammatory dendritic cells (DCs). Analysis of genetically deficient mice revealed that differentiation of iNOS⁺ inflammatory DC, granuloma formation and control of bacterial growth were deeply affected by the absence of MyD88, IL-12p35 and IFN-γ molecules. During chronic phase of infection in susceptible mice, we identified a particular subset of DC expressing both CD11c and CD205, serving as a reservoir for the bacteria. Taken together, our results describe the cellular nature of immune effectors involved during Brucella infection and reveal a previously unappreciated role for DC subsets, both as effectors and reservoir cells, in the pathogenesis of brucellosis.