Diffuse alveolar damage: a common phenomenon in progressive interstitial lung disorders

Lung tissue expression of epithelial injury markers is associated with acute lung injury severity but does not discriminate sepsis from ARDS

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in critically ill patients, and diffuse alveolar damage (DAD) is considered its histological hallmark. Sepsis is one of the most common aetiology of ARDS with the highest case-fatality rate. Identifying ARDS patients and differentiate them from other causes of acute respiratory failure remains a challenge. To address this, many studies have focused on identifying biomarkers that can help assess lung epithelial injury. However, there is scarce information available regarding the tissue expression of these markers. Evaluating the expression of elafin, RAGE, and SP-D in lung tissue offers a potential bridge between serological markers and the underlying histopathological changes. Therefore, we hypothesize that the expression of epithelial injury markers varies between sepsis and ARDS as well as according to its severity.

METHODS

We compared the post-mortem lung tissue expression of the epithelial injury markers RAGE, SP-D, and elafin of patients that died of sepsis, ARDS, and controls that died from non-pulmonary causes. Lung tissue was collected during routine autopsy and protein expression was assessed by immunohistochemistry. We also assessed the lung injury by a semi-quantitative analysis.

RESULTS

We observed that all features of DAD were milder in septic group compared to ARDS group. Elafin tissue expression was increased and SP-D was decreased in the sepsis and ARDS groups. Severe ARDS expressed higher levels of elafin and RAGE, and they were negatively correlated with PaO2/FiO2 ratio, and positively correlated with bronchopneumonia percentage and hyaline membrane score. RAGE tissue expression was negatively correlated with mechanical ventilation duration in both ARDS and septic groups. In septic patients, elafin was positively correlated with ICU admission length, SP-D was positively correlated with serum lactate and RAGE was correlated with C-reactive protein.

CONCLUSIONS

Lung tissue expression of elafin and RAGE, but not SP-D, is associated with ARDS severity, but does not discriminate sepsis patients from ARDS patients.

Frequency of subclinical interstitial lung disease in COVID-19 autopsy cases: potential risk factors of severe pneumonia

Risk factors of severe coronavirus disease 2019 (COVID-19) have been previously reported; however, histological risk factors have not been defined thus far. The aim of this study was to clarify subclinical hidden interstitial lung disease (ILD) as a risk factor of severe pneumonia associated with COVID-19. We carefully examined autopsied lungs and chest computed tomography scanning (CT) images from patients with COVID-19 for interstitial lesions and then analyzed their relationship with disease severity. Among the autopsy series, subclinical ILD was found in 13/27 cases (48%) in the COVID-19 group, and in contrast, 8/65 (12%) in the control autopsy group (p = 0.0006; Fisher's exact test). We reviewed CT images from the COVID-19 autopsy cases and verified that subclinical ILD was histologically detectable in the CT images. Then, we retrospectively examined CT images from another series of COVID-19 cases in the Yokohama, Japan area between February-August 2020 for interstitial lesions and analyzed the relationship to the severity of COVID-19 pneumonia. Interstitial lesion was more frequently found in the group with the moderate II/severe disease than in the moderate I/mild disease (severity was evaluated according to the COVID-19 severity classification system of the Ministry of Health, Labor, and Welfare [Japan]) (moderate II/severe, 11/15, 73.3% versus moderate I/mild, 108/245, 44.1%; Fisher exact test, p = 0.0333). In conclusion, it was suggested that subclinical ILD could be an important risk factor for severe COVID-19 pneumonia. A benefit of these findings could be the development of a risk assessment system using high resolution CT images for fatal COVID-19 pneumonia.

Stratifin as a novel diagnostic biomarker in serum for diffuse alveolar damage

Among the various histopathological patterns of drug-induced interstitial lung disease (DILD), diffuse alveolar damage (DAD) is associated with poor prognosis. However, there is no reliable biomarker for its accurate diagnosis. Here, we show stratifin/14-3-3σ (SFN) as a biomarker candidate found in a proteomic analysis. The study includes two independent cohorts (including totally 26 patients with DAD) and controls (total 432 samples). SFN is specifically elevated in DILD patients with DAD, and is superior to the known biomarkers, KL-6 and SP-D, in discrimination of DILD patients with DAD from patients with other DILD patterns or other lung diseases. SFN is also increased in serum from patients with idiopathic DAD, and in lung tissues and bronchoalveolar lavage fluid of patients with DAD. In vitro analysis using cultured lung epithelial cells suggests that extracellular release of SFN occurs via p53-dependent apoptosis. We conclude that serum SFN is a promising biomarker for DAD diagnosis.

COVID-19 lung disease shares driver AT2 cytopathic features with Idiopathic pulmonary fibrosis

BACKGROUND

In the aftermath of Covid-19, some patients develop a fibrotic lung disease, i.e., post-COVID-19 lung disease (PCLD), for which we currently lack insights into pathogenesis, disease models, or treatment options.

METHODS

Using an AI-guided approach, we analyzed > 1000 human lung transcriptomic datasets associated with various lung conditions using two viral pandemic signatures (ViP and sViP) and one covid lung-derived signature. Upon identifying similarities between COVID-19 and idiopathic pulmonary fibrosis (IPF), we subsequently dissected the basis for such similarity from molecular, cytopathic, and immunologic perspectives using a panel of IPF-specific gene signatures, alongside signatures of alveolar type II (AT2) cytopathies and of prognostic monocyte-driven processes that are known drivers of IPF. Transcriptome-derived findings were used to construct protein-protein interaction (PPI) network to identify the major triggers of AT2 dysfunction. Key findings were validated in hamster and human adult lung organoid (ALO) pre-clinical models of COVID-19 using immunohistochemistry and qPCR.

FINDINGS

COVID-19 resembles IPF at a fundamental level; it recapitulates the gene expression patterns (ViP and IPF signatures), cytokine storm (IL15-centric), and the AT2 cytopathic changes, e.g., injury, DNA damage, arrest in a transient, damage-induced progenitor state, and senescence-associated secretory phenotype (SASP). These immunocytopathic features were induced in pre-clinical COVID models (ALO and hamster) and reversed with effective anti-CoV-2 therapeutics in hamsters. PPI-network analyses pinpointed ER stress as one of the shared early triggers of both diseases, and IHC studies validated the same in the lungs of deceased subjects with COVID-19 and SARS-CoV-2-challenged hamster lungs. Lungs from tg-mice, in which ER stress is induced specifically in the AT2 cells, faithfully recapitulate the host immune response and alveolar cytopathic changes that are induced by SARS-CoV-2.

INTERPRETATION

Like IPF, COVID-19 may be driven by injury-induced ER stress that culminates into progenitor state arrest and SASP in AT2 cells. The ViP signatures in monocytes may be key determinants of prognosis. The insights, signatures, disease models identified here are likely to spur the development of therapies for patients with IPF and other fibrotic interstitial lung diseases.

FUNDING

This work was supported by the National Institutes for Health grants R01- GM138385 and AI155696 and funding from the Tobacco-Related disease Research Program (R01RG3780).

Clinical characteristics and histopathology of COVID-19 related deaths in South African adults

Comparisons of histopathological features and microbiological findings between decedents with respiratory symptoms due to SARS-CoV-2 infection or other causes, in settings with high prevalence of HIV and Mycobacterium tuberculosis (MTB) infections have not been reported. Deaths associated with a positive ante-mortem SARS-CoV-2 PCR test and/or respiratory disease symptoms at Chris Hani Baragwanath Academic Hospital in Soweto, South Africa from 15th April to 2nd November 2020, during the first wave of the South African COVID-19 epidemic, were investigated. Deceased adult patients had post-mortem minimally-invasive tissue sampling (MITS) performed to investigate for SARS-CoV-2 infection and molecular detection of putative pathogens on blood and lung samples, and histopathology examination of lung, liver and heart tissue. During the study period MITS were done in patients displaying symptoms of respiratory disease including 75 COVID-19-related deaths (COVID+) and 42 non-COVID-19-related deaths (COVID-). The prevalence of HIV-infection was lower in COVID+ (27%) than in the COVID- (64%), MTB detection was also less common among COVID+ (3% vs 13%). Lung histopathology findings showed differences between COVID+ and COVID- in the severity of the morphological appearance of Type-II pneumocytes, alveolar injury and repair initiated by SARS-CoV-2 infection. In the liver necrotising granulomatous inflammation was more common among COVID+. No differences were found in heart analyses. The prevalence of bacterial co-infections was higher in COVID+. Most indicators of respiratory distress syndrome were undifferentiated between COVID+ and COVID- except for Type-II pneumocytes. HIV or MTB infection does not appear in these data to have a meaningful correspondence with COVID-related deaths.

Pulmonary Toxicities of Immunotherapy

Immune checkpoint inhibitors are a form of immunotherapy that are increasingly being used in a wide variety of cancers. Immune-related adverse events (irAEs) pose a major challenge in the treatment of cancer patients. Pneumonitis, the most common lung irAE, can cause significant disruptions in the treatment of cancer and may be life-threatening. The goal of this chapter is to instruct readers on the incidence and clinical manifestations of pneumonitis and to offer guidance in the evaluation and treatment of patients with pneumonitis.

Pulmonary adverse events due to immune checkpoint inhibitors: A literature review

Cancer immunotherapy aims to stimulate the immune system to fight against tumors, utilizing the presentation of molecules on the surface of the malignant cells that can be recognized by the antibodies of the immune system. Immune checkpoint inhibitors, a type of cancer immunotherapy, are broadly used in different types of cancer, improving patients' survival and quality of life. However, treatment with these agents causes immune-related toxicities affecting many organs. The most frequent pulmonary adverse event is pneumonitis representing a non-infective inflammation localized to the interstitium and alveoli. Other lung toxicities include airway disease, pulmonary vasculitis, sarcoid-like reactions, infections, pleural effusions, pulmonary nodules, diaphragm myositis and allergic bronchopulmonary aspergillosis. This review aims to summarize these pulmonary adverse events, underlining the significance of an optimal expeditious diagnosis and management.

Human-Based Advanced in vitro Approaches to Investigate Lung Fibrosis and Pulmonary Effects of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has caused considerable socio-economic burden, which fueled the development of treatment strategies and vaccines at an unprecedented speed. However, our knowledge on disease recovery is sparse and concerns about long-term pulmonary impairments are increasing. Causing a broad spectrum of symptoms, COVID-19 can manifest as acute respiratory distress syndrome (ARDS) in the most severely affected patients. Notably, pulmonary infection with Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), the causing agent of COVID-19, induces diffuse alveolar damage (DAD) followed by fibrotic remodeling and persistent reduced oxygenation in some patients. It is currently not known whether tissue scaring fully resolves or progresses to interstitial pulmonary fibrosis. The most aggressive form of pulmonary fibrosis is idiopathic pulmonary fibrosis (IPF). IPF is a fatal disease that progressively destroys alveolar architecture by uncontrolled fibroblast proliferation and the deposition of collagen and extracellular matrix (ECM) proteins. It is assumed that micro-injuries to the alveolar epithelium may be induced by inhalation of micro-particles, pathophysiological mechanical stress or viral infections, which can result in abnormal wound healing response. However, the exact underlying causes and molecular mechanisms of lung fibrosis are poorly understood due to the limited availability of clinically relevant models. Recently, the emergence of SARS-CoV-2 with the urgent need to investigate its pathogenesis and address drug options, has led to the broad application of in vivo and in vitro models to study lung diseases. In particular, advanced in vitro models including precision-cut lung slices (PCLS), lung organoids, 3D in vitro tissues and lung-on-chip (LOC) models have been successfully employed for drug screens. In order to gain a deeper understanding of SARS-CoV-2 infection and ultimately alveolar tissue regeneration, it will be crucial to optimize the available models for SARS-CoV-2 infection in multicellular systems that recapitulate tissue regeneration and fibrotic remodeling. Current evidence for SARS-CoV-2 mediated pulmonary fibrosis and a selection of classical and novel lung models will be discussed in this review.

Radiographic features and poor prognostic factors of interstitial lung disease with nivolumab for non-small cell lung cancer

Nivolumab can cause interstitial lung disease (ILD), which may be fatal; however, mortality risk factors have not been identified. This postmarketing study evaluated the poor prognostic factors of ILD in nivolumab-treated patients with non-small cell lung cancer (NSCLC) in Japan. Clinical and chest imaging findings for each ILD case were assessed by an expert central review committee, and prognosis was evaluated by radiographic findings, including the presence/absence of peritumoral ground-glass opacity (peritumoral-GGO). Poor prognostic factors were identified by univariate and multivariate Cox regression analysis. Of the 238 patients with nivolumab-induced ILD, 37 died. The main radiographic patterns of ILD were cryptogenic organizing pneumonia/chronic eosinophilic pneumonia-like (53.4%), faint infiltration pattern/acute hypersensitivity pneumonia-like (20.2%), diffuse alveolar damage (DAD)-like (10.9%), and nonspecific interstitial pneumonia-like (6.3%). The main poor prognostic factors identified were DAD-like pattern (highest hazard ratio: 10.72), ≤60 days from the start of nivolumab treatment to the onset of ILD, pleural effusion before treatment, lesion distribution contralateral or bilateral to the tumor, and abnormal change in C-reactive protein (CRP) levels. Of the 37 deaths due to ILD, 17 had DAD-like radiographic pattern, three had peritumoral-GGO, and five had a change in radiographic pattern from non-DAD at the onset to DAD-like. Patients with NSCLC who develop ILD during nivolumab treatment should be managed carefully if they have poor prognostic factors such as DAD-like radiographic pattern, onset of ILD ≤60 days from nivolumab initiation, pleural effusion before nivolumab treatment, lesion distribution contralateral or bilateral to the tumor, and abnormal changes in CRP levels.

Alemtuzumab-associated diffuse alveolar damage - a case report

Background

Identifying causes of alemtuzumab induced respiratory symptoms in Multiple Sclerosis (MS) patients is crucial.

Case presentation

We report a case of diffuse alveolar damage (DAD) in a patient with MS after the first course of alemtuzumab treatment. A 42-year-old female developed progressive non-productive cough and exertional dyspnea 2 months after alemtuzumab treatment. DAD was diagnosed histopathologically by lung biopsy. The patient recovered completely, alemtuzumab was not continued.

Conclusions

Our case highlights another pathomechanism for non-infective lung-disorders in alemtuzumab treated MS patients. DAD is a potential, albeit rare side effect of alemtuzumab, broadening the spectrum of non-infective lung disorders that should be considered in the diagnostic work-up.

Immune checkpoint inhibitor-associated interstitial lung diseases correlate with better prognosis in patients with advanced non-small-cell lung cancer

Background

Interstitial lung disease (ILD) induced by immune checkpoint inhibitors (ICIs) is a potentially life‐threatening adverse event. The purpose of this study was to evaluate whether the development of immune‐related adverse events (irAEs), especially ILD, was associated with treatment efficacy and to research the features and risk factors of ILD in advanced non‐small cell lung cancer (NSCLC).

Methods

Between December 2015 and November 2018, 130 advanced NSCLC patients were treated with nivolumab, pembrolizumab or atezolizumab. The patients were categorized into two groups (irAEs group or non‐irAEs group). Subsequently, we divided the irAEs group into two groups based on the incidence of ILD (ILD group and irAEs‐non‐ILD group). Treatment efficacy and the characteristics of ILD were evaluated.

Results

A total of 39 (30%) patients developed irAEs. ILD was observed in 16 (12%) patients. Patients with ILD had a higher objective response rate (ORR) compared with irAEs‐non‐ILD patients and non‐irAEs patients (63%, 43% and 22%, respectively). Median progression‐free survival (mPFS) was 15.9 months in ILD patients, 5.4 months in irAEs‐non‐ILD patients and 3.3 months in non‐irAEs patients (log‐rank test, P = 0.033). Pre‐existing interstitial pneumonia (IP) was an independent risk factor for ILD‐induced ICIs (odds ratio [OR] 14.7; 95% confidence interval [CI]: 2.16–99.6, P = 0.006).

Conclusions

ORR and PFS were significantly better in ILD patients than in irAEs‐non‐ILD and non‐irAEs patients. Pre‐existing history of IP was an independent risk factor for ILD‐induced ICIs.

Immune-Related Adverse Events: Pneumonitis

Checkpoint inhibitors are part of the family of immunotherapies and are increasingly being used in a wide variety of cancers. Immune-related adverse events pose a major challenge in the treatment of cancer patients. Pneumonitis is a rare immune-related adverse event that presents in distinct patterns. The goal of this chapter is to instruct readers on the incidence and clinical manifestations of pneumonitis and to offer guidance in the evaluation and treatment of patients with pneumonitis.

Interstitial Lung Disease Onset and Its Risk Factors in Japanese Patients With ALK-Positive NSCLC After Treatment With Crizotinib

INTRODUCTION

The study objective was to determine the incidence and characteristics of drug-induced interstitial lung disease (ILD) associated with an orally available small-molecule tyrosine kinase inhibitor, crizotinib, in a real-world clinical setting.

METHODS

Post-marketing surveillance was performed in Japan to obtain information on the safety and efficacy of crizotinib. Target patients included all patients with anaplastic lymphoma kinase-positive NSCLC who received crizotinib during the enrollment period between May 2012 and December 2014. The observation period was 52 weeks. Expert analysis of the ILD incidence was performed by an ILD independent review committee composed of five medical specialists.

RESULTS

The safety analysis set included 2028 patients, and more than half of the patients (56.4%) were nonsmokers. The incidence of ILD associated with crizotinib therapy was 5.77%; and 3.45% patients showed grade 3 or greater. Pulmonary edema-like shadows with or without diffuse alveolar damage pattern were observed in crizotinib-associated ILD (incidence: 0.39%), but a causal relationship with the prognosis could not be identified. ILD developed within 4 weeks from initiation of crizotinib administration in 41.9% and within 8 weeks in 69.2% of the patients. Age 55 years or older, Eastern Cooperative Oncology Group performance status 2-4, smoking history, previous or concomitant ILD, and comorbid pleural effusion were statistically determined as significant risk factors for crizotinib-induced ILD.

CONCLUSIONS

Crizotinib therapy should be applied to the NSCLC patients with any of above risk factors under a cautious monitoring for ILD occurrence, and clinicians should pay attention to the risks of severe ILD.

Immune-Related Adverse Events: Pneumonitis

Checkpoint inhibitors are part of the family of immunotherapies and are increasingly being used in a wide variety of cancers. Immune-related adverse events pose a major challenge in the treatment of cancer patients. Pneumonitis is a rare immune-related adverse event that presents in distinct patterns. The goal of this chapter is to instruct readers on the incidence and clinical manifestations of pneumonitis and to offer guidance in the evaluation and treatment of patients with pneumonitis.

Roles of high-mobility group box 1 and thrombin in murine pulmonary fibrosis and the therapeutic potential of thrombomodulin

Cross talk between inflammation and coagulation plays important roles in acute or subacute progressive pulmonary fibrosis characterized by diffuse alveolar damage. Thrombomodulin is a physiological inhibitor of high-mobility group box 1 (HMGB1), and thrombin and may be effective for this condition. This study investigated the roles of HMGB1 and thrombin in the pathophysiology of bleomycin-induced pulmonary fibrosis and the efficacy of recombinant human soluble thrombomodulin (rhTM). Pulmonary fibrosis was induced in wild-type C57BL/6 mice by intratracheal instillation of bleomycin. We first assessed HMGB1, thrombin, transforming growth factor (TGF)-β1, and α-smooth muscle actin (SMA) levels in bronchoalveolar lavage fluid and lung tissue sections over time. Expression of HMGB1 and thrombin was elevated before that of TGF-β1 and α-SMA and remained high during the fibrotic phase after bleomycin instillation. We next examined whether in vitro stimulation with HMGB1 and thrombin induced expression of TGF-β1 and α-SMA in cultured alveolar macrophages and lung fibroblasts, respectively, by performing quantitative PCR, enzyme-linked immunosorbent assay, Western blot, and immunofluorescence analyses. HMGB1 and thrombin stimulation induced TGF-β1 production by alveolar macrophages, and thrombin stimulation also induced α-SMA expression in lung fibroblasts. Finally, we evaluated the effect of rhTM on bleomycin-induced pulmonary fibrosis. Compared with the vehicle control, both early and late-phase administration of rhTM suppressed the fibrotic process. Our results suggest that HMGB1 and thrombin were involved in the pathophysiology of pulmonary fibrosis via production of profibrotic proteins and that rhTM attenuated bleomycin-induced pulmonary fibrosis. rhTM may be a therapeutic option for acute or subacute pulmonary fibrosis.

High-dose steroid therapy for acute respiratory distress syndrome lacking common risk factors: predictors of outcome

Aim

Acute respiratory distress syndrome (ARDS) is a life-threatening lung disease that usually occurs in patients with the underling risk factors that triggers lung inflammation. We sometimes encounter patients with ARDS lacking common risk factors. Recent studies have indicated the effectiveness of corticosteroids for this cohort. However, the characteristics of survivors with ARDS who lack common risk factors, and who received high-dose methylprednisolone pulse therapy (MPPT), are not known.

Methods

We undertook a retrospective study of patients with ARDS lacking common risk factors, who received i.v. MPPT for 3 days. The patients (n = 46) were classified into two groups, survivors (n = 23) and non-survivors (n = 23), based on their survival at 60 days after the initiation of MPPT, and their clinical and radiological parameters were evaluated.

Results

The patient characteristics and disease severity of the two groups were comparable. The percentage of consolidation/(ground-glass attenuation [GGA] + consolidation) on the chest computed tomography scans of survivors was significantly lower than that of non-survivors (survivors, 5.63% [2.31-13.8] versus non-survivors, 27.2% [5.97-41.4]; P = 0.01). In the stratified analysis, the percentage of consolidation/(GGA + consolidation) was significantly associated with 60-day survival.

Conclusions

Our results show that the percentage of consolidation/(GGA + consolidation) on the chest CT scans is an independent prognostic factor for patients with ARDS lacking common risk factors after MPPT.

Airway and parenchyma immune cells in influenza A(H1N1)pdm09 viral and non-viral diffuse alveolar damage

Background

Diffuse alveolar damage (DAD), which is the histological surrogate for acute respiratory distress syndrome (ARDS), has a multifactorial aetiology. Therefore it is possible that the immunopathology differs among the various presentations of DAD. The aim of this study is to compare lung immunopathology of viral (influenza A(H1N1)pdm09) to non-viral, extrapulmonary aetiologies in autopsy cases with DAD.

Methods

The lung tissue of 44 patients, was divided in the H1N1 group (n = 15) characterized by severe pulmonary injury due to influenza A(H1N1)pdm09 infection; the ARDS group (n = 13), characterized by patients with DAD due to non-pulmonary causes; and the Control group (n = 16), consisting of patients with non-pulmonary causes of death. Immunohistochemistry and image analysis were used to quantify, in the parenchyma and small airways, several immune cell markers.

Results

Both DAD groups had higher expression of neutrophils and macrophages in parenchyma and small airways. However, there was a higher expression of CD4+ and CD8+ T lymphocytes, CD83+ dendritic cells, granzyme A+ and natural killer + cell density in the lung parenchyma of the H1N1 group (p < 0.05). In the small airways, there was a lower cell density of tryptase + mast cells and dendritic + cells and an increase of IL-17 in both DAD groups (p < 0.05).

Conclusion

DAD due to viral A(H1N1)pdm09 is associated with a cytotoxic inflammatory phenotype, with partially divergent responses in the parenchyma relative to the small airways. In non-viral DAD, main immune cell alterations were found at the small airway level, reinforcing the role of the small airways in the pathogenesis of the exudative phase of DAD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0630-x) contains supplementary material, which is available to authorized users.

Asymmetry in acute exacerbation of idiopathic pulmonary fibrosis

Acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF) results in poor survival. The objective of the present study was to elucidate the impact of asymmetrical ground-glass opacity (GGO) and/or consolidation on outcomes in patients with AE-IPF. The cases of 59 consecutive patients with AE-IPF were retrospectively reviewed. High-resolution computed tomography (HRCT) at diagnosis of an AE was assessed to determine the disease extent and asymmetry. Asymmetrical AE was defined as a right-to-left ratio of GGO and consolidation ≥2.0 or ≤0.5. The impacts of HRCT indices and other clinical parameters on 180-day mortality were analysed. The overall 180-day mortality rate was 59.2%, and asymmetrical AE was observed in 13 patients (22.0%). A multivariate analysis revealed that asymmetrical AE was a significant predictor of 180-day mortality (hazard ratio=0.36, p=0.047), long-term oxygen therapy before AE and serum lactate dehydrogenase levels. The 180-day mortality of patients with asymmetrical AE was significantly lower than that of patients with symmetrical AE (asymmetrical AE 30.8% versus symmetrical AE 68.2%, p=0.03). An asymmetrical distribution of GGO and/or consolidation is a predictor of survival in patients with AE-IPF.

Keratin14 mRNA expression in human pneumocytes during quiescence, repair and disease

The lung alveoli slowly self-renew pneumocytes, but their facultative regeneration capacity is rapidly efficient after an injury, so fibrosis infrequently occurs. We recently observed Keratin 14 (KRT14) expression during diffuse alveolar damage (DAD), but not in controls. We wonder if KRT14 may be a marker of pneumocyte transition from quiescence to regeneration. Quantitative PCR and Western blot analyses highlighted the presence of KRT14 (mRNA and protein) only in human lung samples with DAD or interstitial lung disease (ILD). In the exponentially growing cell lines A549 and H441, the mRNA and protein levels of KRT14 peaked at day one after cell seeding and decreased at day two, opposite to what observed for the proliferation marker E2F1. The inverse relation of KRT14 versus E2F1 expression holds true also for other proliferative markers, such as cyclin E1 and cyclin D1. Of interest, we also found that E2F1 silencing caused cell cycle arrest and increased KRT14 expression, whilst E2F1 stimulation induced cell cycle progression and decreased KRT14. KRT14 also increased in proliferative pneumocytes (HPAEpiC) just before transdifferentiation. Overall, our results suggest that KRT14 is a viable biomarker of pneumocyte activation, and repair/regeneration. The involvement of KRT14 in regenerative process may suggest a novel pharmaceutical target to accelerate lung repair.

Imaging of Idiopathic Pulmonary Fibrosis

Idiopathic interstitial pneumonias are a heterogeneous group of diffuse lung diseases characterized by distinct clinicopathologic entities with the usual interstitial pneumonia (UIP) being the most common. The pattern of UIP can be seen in idiopathic pulmonary fibrosis (IPF) as well as in secondary causes, most commonly in connective tissue diseases. IPF is usually progressive and associated with a very poor prognosis, and newer therapies pose a risk of serious complications; therefore, diagnostic certainty is crucial. This article reviews the radiologic findings in UIP with clinical correlation and histopathologic features along with its significance for prognosis and patients monitoring.

Prognostic evaluation by oxygenation with positive end-expiratory pressure in acute exacerbation of idiopathic pulmonary fibrosis: A retrospective cohort study

INTRODUCTION

Acute exacerbation (AE) is a severe complication of idiopathic pulmonary fibrosis (IPF), which shares some common pathological features with acute respiratory distress syndrome (ARDS). The new definition of ARDS requires positive end-expiratory pressure (PEEP) to assess gas exchange and has better predictive validity for short-term mortality compared with the previous definition.

OBJECTIVES

The aim of this study was to evaluate the prognostic utility of oxygenation with PEEP in AE-IPF.

METHODS

We performed a retrospective cohort study using the data of AE-IPF patients between 2007 and 2015. At the time of diagnosis, PaO₂ /FiO₂ was evaluated before and 30 minutes after PEEP. We evaluated the prognostic utility of PaO₂ /FiO₂ with PEEP after including other candidate prognostic factors. Considering the definition of ARDS, patients with AE-IPF were classified into a severe group (PaO₂ /FiO₂  ≤ 300 with PEEP) and a non-severe group (PaO₂ /FiO₂  > 300 with PEEP).

RESULTS

We identified 62 consecutive patients with AE-IPF. All patients were treated with mechanical ventilation on the first day. The median PaO₂ /FiO₂ before and 30 minutes after PEEP was significantly increased (237.5-425.5, P < .001). In multivariate Cox proportional analysis, Krebs von den Lungen-6 (KL-6) (HR 1.239; 95%CI 1.050-1.461; P = .011), D-dimer (HR 1.039; 95%CI 1.015-1.064; P = .001), % neutrophils in bronchoalveolar lavage fluid (HR 1.015; 95%CI 1.003-1.027; P = .017), and being in the severe group (HR 3.233; 95%CI 1.503-6.957; P = .003) had significant impacts on survival up to 90 days.

CONCLUSION

Evaluation of oxygenation with PEEP may provide useful information for predicting short-term mortality in patients with AE-IPF.

Therapeutic advances in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterised by progressive accumulation of scar tissue in the lung and is associated with a median life expectancy of 2-4 years. Until recently, treatment options were limited, focusing on ineffective anti-inflammatory therapy, palliation, transplant or trial recruitment. Significant recent advances in the field have led to two novel anti-fibrotic agents, pirfenidone and nintedanib, which have been shown to significantly slow disease progression in IPF. This article outlines the approach to management of IPF, the role of specialist centres and specialist interstitial lung disease multidisciplinary review, and explores both the trial evidence and practical considerations in the use of these anti-fibrotic agents.

Airspace-Occupying Diseases

Diseases of the air space of the lung share many common findings and presentation that it makes more sense to be grouped together in a differential diagnosis. The common imaging finding is usually as a lung infiltrate or consolidation of some type of distribution or another. Trying to find the putative cause for the imaging pattern is a good first step in narrowing the differential diagnosis and answering the question: what accounts for this pattern on imaging studies? Most of these diseases have an acute or subacute onset and exhibit restrictive pattern on pulmonary function tests. When treated promptly, they resolve completely with little or no residual injury to the lung architecture.

On a small biopsy it is important to have a clinical history and imaging results before embarking on a descriptive rather than a definitive diagnosis. The smaller the sample, the more information is needed to complete the picture. Pulmonologists should be advised to target the part of the lung that should provide the most information related to the process under investigation. An endobronchial wall biopsy is not suitable in the setting of investigating a lung infiltrate as part of the alveolated lung has to be included.

The category of airspace-occupying diseases of the lung includes:

Acute lung infections such as bacterial and viral pneumonias

Acute lung injury pattern which includes bronchiolitis obliterans/organizing pneumonia and diffuse alveolar damage

Intra-alveolar hemorrhage

Pulmonary alveolar proteinosis

Pulmonary edema

Pneumocystis pneumonia

Lymphangitic carcinomatosis

In all of these instances, there are ground-glass opacities obscuring the air space. Most clinicians would describe the imaging as “infiltrate” or “consolidation.” The task for the pathologist is to find the pertinent finding that could account for the imaging.

Immunohistochemical detection of virus through its nuclear cytopathic effect in idiopathic interstitial pneumonia other than acute exacerbation

Idiopathic interstitial pneumonias include complex diseases that have a strong interaction between genetic makeup and environmental factors. However, in many cases, no infectious agent can be demonstrated, and these clinical diseases rapidly progress to death. Theoretically, idiopathic interstitial pneumonias could be caused by the Epstein-Barr virus, cytomegalovirus, adenovirus, hepatitis C virus, respiratory syncytial virus, and herpesvirus, which may be present in such small amounts or such configuration that routine histopathological analysis or viral culture techniques cannot detect them. To test the hypothesis that immunohistochemistry provides more accurate results than the mere histological demonstration of viral inclusions, this method was applied to 37 open lung biopsies obtained from patients with idiopathic interstitial pneumonias. As a result, immunohistochemistry detected measles virus and cytomegalovirus in diffuse alveolar damage-related histological patterns of acute exacerbation of idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia in 38 and 10% of the cases, respectively. Alveolar epithelium infection by cytomegalovirus was observed in 25% of organizing pneumonia patterns. These findings were coincident with nuclear cytopathic effects but without demonstration of cytomegalovirus inclusions. These data indicate that diffuse alveolar damage-related cytomegalovirus or measles virus infections enhance lung injury, and a direct involvement of these viruses in diffuse alveolar damage-related histological patterns is likely. Immunohistochemistry was more sensitive than the histological demonstration of cytomegalovirus or measles virus inclusions. We concluded that all patients with diffuse alveolar damage-related histological patterns should be investigated for cytomegalovirus and measles virus using sensitive immunohistochemistry in conjunction with routine procedures.

The current position of surgical lung biopsy in the diagnosis of idiopathic pulmonary fibrosis

A new international statement defines usual interstitial pneumonia (UIP) which is a histological and radiological form of idiopathic pulmonary fibrosis (IPF) more precisely than previously. In the diagnosis of IPF, either in high resolution computed tomography (HRCT) a UIP pattern must be present or alternatively specific combinations of HRCT and surgical lung biopsy findings can be accepted. In about two third of the cases IPF can be diagnosed by clinical and radiological criteria. Thus surgical lung biopsy is needed in about one third of cases to achieve the ultimate diagnosis, which requires multidisciplinary cooperation. In large clinical trials conducted during the last decade, lung biopsy was performed in about 30-60% of the cases. The most serious complication of lung biopsy is mortality within 30 days after the procedure, with a frequency of about 3-4% reported in most studies. Because of the histological variability, surgical lung biopsy should be taken from a minimum of two lobes. The number of fibroblast foci in surgical lung biopsy has been shown to correlate with survival in several studies.

A case of asymptomatic, localized, and idiopathic diffuse alveolar damage

Diffuse alveolar damage (DAD) is a histological change in lung tissue, and is generally caused by an acute lung injury, which is characterized by bilateral and widespread damages. Localized DAD occurs very rarely. The causes for DAD are numerous, but the chief cause is acute interstitial pneumonia or acute exacerbation of idiopathic interstitial pneumonia, in cases of idiopathic manifestation. The 82-year-old patient, in this case study, showed a DAD lesion in only 1 lobe. The patient was otherwise healthy, with no previous symptoms of DAD. He was admitted to our medical center owing to localized infiltration, observed on his chest radiograph. Laboratory studies showed no signs of infections. DAD was confirmed by a surgical lung biopsy. The patient received corticosteroid treatment and had gradually improved. We report the case of a patient with localized, idiopathic DAD that cannot be classified as acute interstitial pneumonia or acute exacerbation of idiopathic interstitial pneumonia.

Diffuse alveolar hemorrhage in coumarin users: a fibrosing interstitial pneumonia trigger?

BACKGROUND

Fibrosing interstitial pneumonias (IPs) include idiopathic pulmonary fibrosis (IPF) and nonspecific interstitial pneumonia (NSIP). It has been suggested that oxidative damage plays a role in the pathophysiology of idiopathic interstitial pneumonias. Diffuse alveolar hemorrhage (DAH) can cause oxidative stress. Accordingly, we hypothesized that episodes of DAH might trigger fibrosing IP development.

METHODS

Patients using coumarins with confirmed DAH were retrospectively gathered during a 9 year period and reviewed for the development of IPF or fibrosing NSIP.

RESULTS

A total of 65 patients with DAH could finally be included, 31 (48 %) of whom subsequently developed a fibrosing IP. The majority of these 31 patients developed the fibrosing IP within 3 years after DAH confirmation. A total of 41 (63 %) patients died within 3.0 ± 0.9 (range 1.3-4.7) years after the DAH diagnosis had been confirmed. Twenty-two of the deceased (54 %) had finally developed fibrosing IP.

CONCLUSIONS

Almost half of the patients with established episodes of DAH developed fibrosing IP; therefore it seems that DAH might be a trigger for the development of fibrosing IP. This observation warrants prospective studies to further evaluate the clinical impact of these findings.

Diffuse alveolar damage of the lungs in forensic autopsies: assessment of histopathological stages and causes of death

Introduction. Diffuse alveolar damage (DAD) is a morphological prototype of acute interstitial pneumonia. Hospital autopsies or open-lung biopsies are used to monitor common alveolar damage and hyaline membrane (HM) development histopathologically. The aim of this study was to detect histopathological profiles and frequency of DAD and HM in adult forensic autopsies. Materials and Methods. In total, 6813 reports with histopathological samples in 12,504 cases on which an autopsy was performed between 2006 and 2008 were investigated. Sixty-six individuals >18 years of age who were diagnosed with DAD were included. Hematoxylin- and eosin-stained lung preparations were reexamined in line with the 2002 American Thoracic Society/European Respiratory Society idiopathic interstitial pneumonia consensus criteria. Results. Histopathological examination revealed that 50 cases (75.7%) were in the exudative phase and 16 (24.2%) were in the proliferative phase. Only the rate of alveolar exudate/oedema in exudative phase cases (P = 0.003); those of alveolar histiocytic desquamation (P = 0.037), alveolar fibrosis (P = 0.017), chronic inflammation (P = 0.02), and alveolar fibrin (P = 0.001) in proliferative cases were significantly higher. The presence of alveolar fibrin was the only independent variable in favour of proliferative cases (P = 0.016). Conclusion. The detection of all DAD morphological criteria with the same intensity is not always possible in each case. Forensic autopsies may provide a favourable means for expanding our knowledge about acute lung damage, DAD, and interstitial lung disease.

Drug induced interstitial lung disease

With an increasing number of therapeutic drugs, the list of drugs that is responsible for severe pulmonary disease also grows. Many drugs have been associated with pulmonary complications of various types, including interstitial inflammation and fibrosis, bronchospasm, pulmonary edema, and pleural effusions. Drug-induced interstitial lung disease (DILD) can be caused by chemotherapeutic agents, antibiotics, antiarrhythmic drugs, and immunosuppressive agents. There are no distinct physiologic, radiographic or pathologic patterns of DILD, and the diagnosis is usually made when a patient with interstitial lung disease (ILD) is exposed to a medication known to result in lung disease. Other causes of ILD must be excluded. Treatment is avoidance of further exposure and systemic corticosteroids in patients with progressive or disabling disease.