Chronic lung allograft pathology lesions in two rat strain combinations

Background

Chronic lung allograft dysfunction remains an obstacle to long-term survival after lung transplantation. Two phenotypes have been described: obliterative bronchiolitis and restrictive allograft syndrome. Preclinical models are essential to analyze chronic lung allograft dysfunction pathophysiology.

Methods

Orthotopic lung transplants from 38 Lewis into Fischer 344 (Lew→F344) and 67 Brown-Norway into Lewis (BN→Lew) rats were performed in our center in the last decade. We carefully reviewed and quantified all grafts with chronic rejection (40 cases) (18 Lew→F344, 22 BN→Lew) with the aim to investigate if histological changes of chronic lung allograft dysfunction could be also detected in rat grafts.

Results

All animals showed human reminiscent histological lesions. Early chronic rejection lesions were detected in BN→Lew. End-stage chronic rejection with features of obliterative bronchiolitis was observed in 33% of Lew→F344; end-stage with restrictive allograft syndrome chronic rejection in 67% and 80% of Lew→F344 and BN→Lew, respectively. BN→Lew showed higher grades of endotheliitis, vascular fibrosis, and lower grades of lymphoid aggregates than Lew→F344 (P=0.007, P=0.043, P=0.004, respectively).

Conclusions

Chronic rejection lesions in rat lung allografts mimic those in humans. The frequent occurrence of restrictive allograft syndrome-like lesions in BN→Lew may be related to a higher degree of mismatch in this strain combination. These animal models could allow future mechanistic studies to better understand chronic lung allograft dysfunction pathogenesis.

The Diagnostic Yield of the Multidisciplinary Discussion in Patients With COVID-19 Pneumonia

Purpose: The hypothesis of the study was that a multidisciplinary approach involving experienced specialists in diffuse parenchymal lung disease might improve the diagnosis of patients with COVID-19 pneumonia.

Methods: Two pulmonologists, two radiologists, and two pathologists reviewed 27 patients affected by severe COVID-19 pneumonia as the main diagnosis made by non-pulmonologists. To evaluate whether the contribution of specialists, individually and/or in combination, might modify the original diagnosis, a three-step virtual process was planned. The whole lung examination was considered the gold standard for the final diagnosis. The probability of a correct diagnosis was calculated using a model based on generalized estimating equations. The effectiveness of a multidisciplinary diagnosis was obtained by comparing diagnoses made by experienced pulmonologists with those made by non-pulmonologists.

Results: In 19% of cases, the diagnosis of COVID-19-related death was mainly incorrect. The probability of a correct diagnosis increased strikingly from an undedicated clinician to an expert specialist. Every single specialist made significantly more correct diagnoses than any non-pulmonologist. The highest level of accuracy was achieved by the combination of 3 expert specialists (p = 0.0003).

Conclusion: The dynamic interaction between expert specialists may significantly improve the diagnostic confidence and management of patients with COVID-19 pneumonia.

Organ Care System Lung resulted in lower apoptosis and iNOS expression in donor lungs

Ischemia-reperfusion (IR) injury after lung transplantation is still today an important complication in up to 25% of patients. The Organ Care System (OCS) Lung, an advanced normothermic ex vivo lung perfusion system, was found to be effective in reducing primary graft dysfunction compared to standard organ care (SOC) but studies on tissue/molecular pathways that could explain these more effective clinical results are lacking. This observational longitudinal study aimed to investigate IR injury in 68 tissue specimens collected before and after reperfusion from 17 OCS and 17 SOC preserved donor lungs. Several tissue analyses including apoptosis evaluation and inducible nitric oxide synthase (iNOS) expression (by immunohistochemistry and real-time reverse transcriptase-polymerase chain reaction) were performed. Lower iNOS expression and apoptotic index were distinctive of OCS preserved tissues at pre- and post-reperfusion times, independently from potential confounding factors. Moreover, OCS recipients had lower acute cellular rejection at the first 6-month follow-up. In conclusion, IR injury, in terms of apoptosis and iNOS expression, was less frequent in OCS- than in SOC-preserved lungs, which could eventually explain a better clinical outcome. Further studies are needed to validate our data and determine the role of iNOS expression as a predictive biomarker of the complex IR injury mechanism.

Are There New Biomarkers in Tissue and Liquid Biopsies for the Early Detection of Non-Small Cell Lung Cancer?

Lung cancer is one of the most lethal malignancies worldwide, mainly due to its late diagnoses. The detection of molecular markers on samples provided from routine bronchoscopy including several liquid-based cytology tests (e.g., bronchoaspirate, bronchoalveolar lavage) and/or on easily obtained specimens such as sputum could represent a new approach to improve the sensitivity in lung cancer diagnoses. Recently growing interest has been reported for "noninvasive" liquid biopsy as a valuable source for molecular profiling. Unfortunately, a biomarker and/or composition of biomarkers capable of detecting early-stage lung cancer has yet to be discovered even if in the last few years there has been, through the use of revolutionary new technologies, an explosion of lung cancer biomarkers. Assay sensitivity and specificity need to be improved particularly when new approaches and/or tools are used. We have focused on the most important markers detected in tissue, and on several cytological specimens and liquid biopsies overall.

Idiopathic Pulmonary Fibrosis and Antifibrotic Treatments: Focus on Experimental Studies

Context.—

Idiopathic pulmonary fibrosis (IPF) is a progressive fatal disease that up to now has been associated with a poor outcome. Some advances have been made in understanding the multiple interrelated pathogenic pathways underlying IPF. The disease is now believed to result from complex interactions among genetic, epigenetic, transcriptional, posttranscriptional, metabolic, and environmental factors. The discovery and validation of theranostic biomarkers are necessary to enable a more precise and earlier diagnosis of IPF and to improve the prediction of future disease behavior. Two drugs recently approved by the US Food and Drug Administration, pirfenidone and nintedanib, have shown the ability to reduce the progression of the disease, although survival benefits are only minimal and neither drug prevents or reverses the disease.

Objective.—

To provide a critical overview of the main experimental studies carried out for testing the principal effects of pirfenidone and nintedanib on IPF.

Data Sources.—

Experimental (animal and in vitro) studies concerning both drugs were used.

Conclusions.—

Pirfenidone has a longer history of preclinical experimental studies than nintedanib. Many studies have been reported more recently (after 2014) and some of them evaluated the association of both drugs, thus suggesting their combination in future therapeutic approaches. Future investigations focusing on targets at molecular, cellular, and tissue levels are necessary to have a better in-depth knowledge of the properties of these drugs and to explore the potential efficacy of both or other drug combinations.

Overexpression of Hypoxia-Inducible Factor-1α in Primary Graft Dysfunction Developing in an Orthotopic Lung Transplantation Rat Model

BACKGROUND

Primary graft dysfunction (PGD) is the major cause of early morbidity and mortality after transplantation. A high rate of PGD is a frequent complication in orthotopic lung transplantation (OLT) models, which are currently used to investigate acute and chronic rejection pathways. Hypoxia-inducible factor (HIF)-1α is a heterodimeric αβ transcription factor that mediates tissue response to hypoxia. In other solid organ transplantations, a significant correlation between HIF-1α expression and PGD was detected. To our knowledge no data are available on HIF-1α expression in PGD developing in lung transplantation. The aims of this study were to investigate HIF-1α expression (using immunohistochemistry) and correlate it to the main histological parameters related to ischemia-reperfusion (IR) injury, including terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) -positive apoptotic cells).

METHODS

OLT was performed in 32 inbred rat strains and 11 of them died in the early postoperative period (from day 0-3) for IR injury. The histological and molecular evaluations were done in all lung tissues. Unimplanted donor rat lungs were used as controls. HIF-1α expression was correlated with all morphological parameters.

RESULTS

Lung samples of animals with IR injury showed high scores of HIF-1α expression, edema, blood extravasation, granulocyte margination, apoptotic index, and necrosis in 91% of cases. Tissue overexpression of HIF-1α was detected in all lung samples with high scores of histological parameters and with high apoptotic indexes.

CONCLUSION

Our data demonstrate that HIF-1α was overexpressed in more severe rat lung IR injury. The use of HIF-1α inhibitors could provide a translatable route into manipulating this complex system in vivo.

Absence of Neurofibromin Induces an Oncogenic Metabolic Switch via Mitochondrial ERK-Mediated Phosphorylation of the Chaperone TRAP1

Mutations in neurofibromin, a Ras GTPase-activating protein, lead to the tumor predisposition syndrome neurofibromatosis type 1. Here, we report that cells lacking neurofibromin exhibit enhanced glycolysis and decreased respiration in a Ras/ERK-dependent way. In the mitochondrial matrix of neurofibromin-deficient cells, a fraction of active ERK1/2 associates with succinate dehydrogenase (SDH) and TRAP1, a chaperone that promotes the accumulation of the oncometabolite succinate by inhibiting SDH. ERK1/2 enhances both formation of this multimeric complex and SDH inhibition. ERK1/2 kinase activity is favored by the interaction with TRAP1, and TRAP1 is, in turn, phosphorylated in an ERK1/2-dependent way. TRAP1 silencing or mutagenesis at the serine residues targeted by ERK1/2 abrogates tumorigenicity, a phenotype that is reverted by addition of a cell-permeable succinate analog. Our findings reveal that Ras/ERK signaling controls the metabolic changes orchestrated by TRAP1 that have a key role in tumor growth and are a promising target for anti-neoplastic strategies.

Idiopathic pulmonary fibrosis: Are any of the morphological-molecular markers useful in clinical management?

Idiopathic pulmonary fibrosis (IPF), the most common form of chronic interstitial lung disease, is a severe progressive fibrotic disorder of unknown aetiology. The disease has a heterogeneous clinical course, with frequent poor prognosis, similar to malignant disease. Correctly diagnosing IPF has become particularly important in view of the availability of more precise therapeutic indications, thus avoiding steroid treatment and allowing new approaches with novel drugs. To date we have limited information about biomarkers predictive of progressive disease and associated complications. Efforts should be made in the future to more appropriately study lung tissue and then to extrapolate the most clinically fitting biomarkers. This approach is already used in routine management of many cancers and provides a potential road map for more appropriate clinical care of IPF. This review will mainly focus on histology and etiopathogenesis highlighting some morphological and molecular features that may influence the overall management of IPF.

MDM2 and HIF1alpha expression levels in different histologic subtypes of malignant pleural mesothelioma: correlation with pathological and clinical data

Malignant pleural mesothelioma (MPM) is an aggressive tumor with poor prognosis and limited treatment options. Sarcomatoid/biphasic mesotheliomas are characterized by more aggressive behaviour and a poorer prognosis compared with the epithelioid subtype. To date prognostic and tailored therapeutic biomarkers are lacking. The present study analyzed the expression levels of MDM2 and HIF1alpha in different histologic subtypes from chemonaive MPM patients. Diagnostic biopsies of MPM patients from four Italian cancer centers were centrally collected and analyzed. MDM2 and HIF1alpha expression levels were investigated through immunohistochemistry and RT-qPCR. Pathological assessment of necrosis, inflammation and proliferation index was also performed. Molecular markers, pathological features and clinical characteristics were correlated to overall survival (OS) and progression free survival (PFS). Sixty MPM patients were included in the study (32 epithelioid and 28 non-epithelioid). Higher levels of MDM2 (p < 0.001), HIF1alpha (p = 0.013), necrosis (p = 0.013) and proliferation index (p < 0.001) were seen mainly in sarcomatoid/biphasic subtypes. Higher levels of inflammation were significantly associated with epithelioid subtype (p = 0.044). MDM2 expression levels were correlated with HIF1alpha levels (p = 0.0001), necrosis (p = 0.008) and proliferation index (p = 0.009). Univariate analysis showed a significant correlation of non-epithelioid histology (p = 0.04), high levels of necrosis (p = 0.037) and proliferation index (p = 0.0002) with shorter PFS. Sarcomatoid/biphasic and epithelioid mesotheliomas showed different MDM2 and HIF1alpha expression levels and were characterized by different levels of necrosis, proliferation and inflammation. Further studies are warranted to confirm a prognostic and predictive role of such markers and features.