Expression of a tumor necrosis factor-alpha transgene in murine lung causes lymphocytic and fibrosing alveolitis. A mouse model of progressive pulmonary fibrosis

Regorafenib exerts an inhibitory effect on the proliferation of human lung fibroblasts by reducing the production of several cytokines in vitro study

BACKGROUND

Pulmonary fibrosis is a disease that leads to respiratory failure and death. There has been little progress in therapeutic strategies for pulmonary fibrosis. There have been several reports on the cytokines associated with pulmonary fibrosis, including IL-6 and TGF-β1. Angiogenesis is one of the most important phenomena in the pathogenesis of pulmonary fibrosis. Previously, we reported the preventive effects of thalidomide against pulmonary fibrosis via the inhibition of neovascularization by angiogenic factors such as VEGF. Regorafenib is a multikinase inhibitor, which inhibits tyrosine kinase receptors such as VEGFR1-3 and TIE2. In the clinical setting, regorafenib has been widely used for anti-cancer therapy for metastatic colorectal cancer. In this study, we examined the preventive effects of regorafenib against pulmonary fibrosis.

METHODS

We investigated whether regorafenib had an inhibitory effect on the proliferation, viability, and production of several cytokines in lung fibroblasts.

RESULTS

We demonstrated an inhibitory effect of regorafenib on the proliferation and viability of lung fibroblasts. Moreover, regorafenib reduced the production of several cytokines associated with the pathogenesis of pulmonary fibrosis, including IL-6, VEGF and TGF- β1, and collagen synthesis from lung fibroblasts.

CONCLUSIONS

These data suggest that regorafenib may have potential clinical applications in the prevention of pulmonary fibrosis.

Integrative analysis of gene expression and chromatin dynamics multi-omics data in mouse models of bleomycin-induced lung fibrosis

BACKGROUND

Pulmonary fibrosis is a relentless and ultimately fatal lung disorder. Despite a wealth of research, the intricate molecular pathways that contribute to the onset of PF, especially the aspects related to epigenetic modifications and chromatin dynamics, continue to be elusive and not fully understood.

METHODS

Utilizing a bleomycin-induced pulmonary fibrosis model, we conducted a comprehensive analysis of the interplay between chromatin structure, chromatin accessibility, gene expression patterns, and cellular heterogeneity. Our chromatin structure analysis included 5 samples (2 control and 3 bleomycin-treated), while accessibility and expression analysis included 6 samples each (3 control and 3 bleomycin-treated).

RESULTS

We found that chromatin architecture, with its alterations in compartmentalization and accessibility, is positively correlated with genome-wide gene expression changes during fibrosis. The importance of immune system inflammation and extracellular matrix reorganization in fibrosis is underscored by these chromatin alterations. Transcription factors such as PU.1, AP-1, and IRF proteins, which are pivotal in immune regulation, are associated with an increased abundance of their motifs in accessible genomic regions and are correlated with highly expressed genes.

CONCLUSIONS

We identified 14 genes that demonstrated consistent changes in their expression, accessibility, and compartmentalization, suggesting their potential as promising targets for the development of treatments for lung fibrosis.

TNF signaling mediates lipopolysaccharide-induced lung epithelial progenitor cell responses in mouse lung organoids

Bacterial respiratory infections are a major global health concern, often leading to lung injury and triggering lung repair mechanisms. Endogenous epithelial progenitor cells are crucial in this repair, yet the mechanisms remain poorly understood. This study investigates the response of lung epithelial progenitor cells to injury induced by lipopolysaccharide (LPS), a component of gram-negative bacteria, focusing on their regulation during lung repair. Lung epithelial cells (CD31-CD45-Epcam+) from wild-type and tumor necrosis factor (TNF) receptor 1/2 knock-out mice were co-cultured with wild-type fibroblasts. Organoid numbers and size were measured after 14 days of exposure to 100 ng/mL LPS. Immunofluorescence was used to assess differentiation (after 14 days), RNA sequencing analyzed gene expression changes (after 72 hours), and MTS assay assessed proliferative effects of LPS on individual cell types (after 24 hours). LPS treatment increased the number and size of wild-type lung organoids and promoted alveolar differentiation, indicated by more SPC+ organoids. RNA sequencing revealed upregulation of inflammatory and fibrosis-related markers, including Cxcl3, Cxcl5, Ccl20, Mmp13, and Il33, and enrichment of TNF-α signaling and epithelial-mesenchymal transition pathways. TNF receptor 1 deficiency inhibited LPS-induced progenitor cell activation and organoid growth. In conclusion, LPS enhances lung epithelial progenitor cell proliferation and differentiation via TNF receptor 1 signaling, highlighting potential therapeutic targets for bacterial lung injury.

Rheumatoid arthritis extra-articular lung disease: new insights on pathogenesis and experimental drugs

INTRODUCTION

Pulmonary involvement is one of the most common extra-articular manifestations of rheumatoid arthritis (RA), a systemic inflammatory disease characterized by joint swelling and tenderness. All lung compartments can be interested in the course of RA, including parenchyma, airways, and, more rarely, pleura and vasculature.

AREAS COVERED

The aim of this paper is to review the main RA lung manifestations, focusing on pathogenesis, clinical and therapeutic issues of RA-related interstitial lung disease (ILD). Despite an increasing number of studies in the last years, pathogenesis of RA-ILD remains largely debated and the treatment of RA patients with lung involvement is still challenging in these patients.

EXPERT OPINION

Management of RA-ILD is largely based on expert-opinion. Due to the broad clinical manifestations, including both joints and pulmonary involvement, multidisciplinary discussion, including rheumatologist and pulmonologist, is essential, not only for diagnosis, but also to evaluate the best therapeutic approach and follow-up. In fact, the coexistence of different lung manifestations may influence the treatment response and safety. The identification of biomarkers and risk-factors for an early identification of RA patients at risk of developing ILD remains a need that still needs to be fulfilled, and that will require further investigation in the next years.

Distinct TNF-alpha and HLA polymorphisms associate with fibrotic and non-fibrotic subtypes of hypersensitivity pneumonitis

INTRODUCTION

Since Hypersensitivity Pneumonitis (HP) categorization in fibrotic and nonfibrotic/inflammatory types seems to be more consistent with the distinctive clinical course and outcomes, recent international guidelines recommended the use of this classification. Moreover, fibrotic subtype may share immunogenetic and pathophysiological mechanisms with other fibrotic lung diseases.

AIM

To investigate HLA -A, -B, -DRB1 and TNF-α -308 gene polymorphisms among fibrotic and nonfibrotic HP patients due to avian exposure, also in comparison with asymptomatic exposed controls.

METHODS

We prospectively enrolled 40 HP patients, classified as fibrotic or nonfibrotic/inflammatory, and 70 exposed controls. HLA and TNF-α polymorphisms were determined by polymerase chain reaction-sequence specific primer amplification.

RESULTS

While HLA alleles were not associated to HP susceptibility, fibrotic HP patients showed increased frequencies of HLA A*02 (46.7% vs 25.7%; OR=2.53, p = 0.02) and HLA DRB1*14 (10.0% vs 0.7%; OR=15.44, p=0.02) alleles when compared with exposed controls, although not statistically significant after correction for multiple comparisons. TNF-α G/G genotype (associated with low TNF-α production) frequencies were significantly increased among the non-fibrotic/inflammatory HP patients comparatively to fibrotic presentations (88% vs 60%; RR=0.44; p=0.04) and controls (88% vs 63%, OR 4.33, p=0.037). Also, these patients had a significantly increased frequency of the G allele (94.0% vs 73.3%, RR=0.44, p=0.01), while fibrotic HP patients predominantly presented the A allele (26.7% vs 6.0%, RR=2.28, p=0.01).

CONCLUSIONS

Our results support the hypothesis that fibrotic and non-fibrotic HP subtypes exhibit a distinct profile of TNF-α and HLA polymorphisms, which may be relevant to predict disease course and better define treatment strategies.

Infliximab-Induced Interstitial Pneumonitis: A Case Report

Anti-tumor necrosis factor inhibitors are increasingly being recommended to treat and control a wide range of diseases, including Crohn's disease, ulcerative colitis, rheumatoid, and psoriatic arthritis. Serious pulmonary consequences, ranging from infectious disease to pulmonary edema, airway involvement, and even interstitial lung disease, are well-known multisystemic side effects. Interstitial lung disease is a well-known but uncommon condition. This report presents a case of a 49-year-old man with ulcerative colitis who developed interstitial pneumonitis following three infusions of infliximab therapy based on clinical, radiologic, and pathology data that are consistent with drug-induced interstitial pneumonitis. After stopping infliximab and starting steroid therapy, we noticed complete symptom resolution and improvement in respiratory symptoms and imaging.

Focus on Anti-Tumour Necrosis Factor (TNF)-α-Related Autoimmune Diseases

Anti-tumour necrosis factor (TNF)-α agents have been increasingly used to treat patients affected by inflammatory bowel disease and dermatological and rheumatologic inflammatory disorders. However, the widening use of biologics is related to a new class of adverse events called paradoxical reactions. Its pathogenesis remains unclear, but it is suggested that cytokine remodulation in predisposed individuals can lead to the inflammatory process. Here, we dissect the clinical aspects and overall outcomes of autoimmune diseases caused by anti-TNF-α therapies.

Combined Pulmonary Fibrosis and Emphysema: When Scylla and Charybdis Ally

Combined pulmonary fibrosis and emphysema (CPFE) is a recently recognized syndrome that, as its name indicates, involves the existence of both interstitial lung fibrosis and emphysema in one individual, and is often accompanied by pulmonary hypertension. This debilitating, progressive condition is most often encountered in males with an extensive smoking history, and is presented by dyspnea, preserved lung volumes, and contrastingly impaired gas exchange capacity. The diagnosis of the disease is based on computed tomography imaging, demonstrating the coexistence of emphysema and interstitial fibrosis in the lungs, which might be of various types and extents, in different areas of the lung and several relative positions to each other. CPFE bears high mortality and to date, specific and efficient treatment options do not exist. In this review, we will summarize current knowledge about the clinical attributes and manifestations of CPFE. Moreover, we will focus on pathophysiological and pathohistological lung phenomena and suspected etiological factors of this disease. Finally, since there is a paucity of preclinical research performed for this particular lung pathology, we will review existing animal studies and provide suggestions for the development of additional in vivo models of CPFE syndrome.

Mesenchymal stem cells in fibrotic diseases-the two sides of the same coin

Fibrosis is caused by extensive deposition of extracellular matrix (ECM) components, which play a crucial role in injury repair. Fibrosis attributes to ~45% of all deaths worldwide. The molecular pathology of different fibrotic diseases varies, and a number of bioactive factors are involved in the pathogenic process. Mesenchymal stem cells (MSCs) are a type of multipotent stem cells that have promising therapeutic effects in the treatment of different diseases. Current updates of fibrotic pathogenesis reveal that residential MSCs may differentiate into myofibroblasts which lead to the fibrosis development. However, preclinical and clinical trials with autologous or allogeneic MSCs infusion demonstrate that MSCs can relieve the fibrotic diseases by modulating inflammation, regenerating damaged tissues, remodeling the ECMs, and modulating the death of stressed cells after implantation. A variety of animal models were developed to study the mechanisms behind different fibrotic tissues and test the preclinical efficacy of MSC therapy in these diseases. Furthermore, MSCs have been used for treating liver cirrhosis and pulmonary fibrosis patients in several clinical trials, leading to satisfactory clinical efficacy without severe adverse events. This review discusses the two opposite roles of residential MSCs and external MSCs in fibrotic diseases, and summarizes the current perspective of therapeutic mechanism of MSCs in fibrosis, through both laboratory study and clinical trials.

Prevention of Bleomycin-Induced Pulmonary Inflammation and Fibrosis in Mice by Bilobalide

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease. Bilobalide (BB) is a sesquiterpene isolated from Ginkgo biloba, and its role in IPF is poorly understood. Mice were intratracheally instilled with 2.5 mg/kg bleomycin (BLM) to induce IPF and then treated with 2.5, 5, and 10 mg/kg BB daily for 21 days. Treatment with BB ameliorated pathological injury and fibrosis of lung tissues in BLM-induced mice. BB suppressed BLM-induced inflammatory response in mice as demonstrated by reduced inflammatory cells counts (leukocytes, neutrophils, macrophages, and lymphocytes) and pro-inflammatory factors (CCL2 and TNF-α), as well as increased CXCL10 levels in BALF. The expression of BLM-induced hydroxyproline, LDH, and pro-fibrotic mediators including fibronectin, collagen I, α-smooth muscle actin (α-SMA), transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-2, and MMP-9 in lung tissue was inhibited by BB treatment, and the tissue inhibitor of metalloproteinase-1 (TIMP-1) expression was increased. BB blocked the phosphorylation of JNK and NF-κB, and the nuclear translocation of NF-κB in the lung tissue of mice induced by BLM. Additionally, it abated the activation of NLRP3 inflammasome in lung tissue induced by BLM, which led to the downregulation of IL-18 and IL-1β in BALF. Our present study suggested that BB might ameliorate BLM-induced pulmonary fibrosis by inhibiting the early inflammatory response, which is probably via the inhibition of the JNK/NF-κB/NLRP3 signal pathway. Thus, BB might serve as a therapeutic potential agent for pulmonary inflammation and fibrosis.

Neutrophil extracellular traps and pulmonary fibrosis: an update

Pulmonary fibrosis (PF) is a serious and often fatal illness that occurs in various clinical settings and represents a significant unmet medical need. Increasing evidence indicates that neutrophil extracellular traps (NETs) contribute significantly to the progression of PF. Therefore, understanding the pathways by which NETs contribute to the disease is crucial for developing effective treatments. This review focuses on the formation of NETs and the common mechanisms of NETs in PF.

Decreased absolute number of peripheral regulatory T cells in patients with idiopathic retroperitoneal fibrosis

Objective

In order to determine whether the immune balance of T helper 17(Th17)/regulatory T(Treg) is related to the pathogenesis of idiopathic retroperitoneal fibrosis (IRPF), we analyzed the differences in peripheral blood lymphocytes, CD4+T cell subsets and cytokines between patients with IRPF and healthy people to clarify the CD4+T cell subsets, especially Treg cell subsets, and the role of cytokines in the pathogenesis of IRPF.

Methods

This study included 22 patients with IRPF, 36 patients with IgG4-related diseases (IgG4-RD) without retroperitoneal fibrosis (RPF), and 28 healthy controls. The absolute numbers and percentage of peripheral blood lymphocyte subsets and CD4+T cell subsets in each group were detected by flow cytometry, and the serum cytokine level was detected by flow cytometric bead array (CBA).

Results

Compared with the healthy group, the absolute value of B cells in peripheral blood of IRPF patients was significantly decreased, and T, natural killer (NK), CD4+ and CD8+ were not significantly abnormal. The absolute numbers of Th2 cells were lower than healthy group(p=0.043). In particular, the absolute numbers of Treg cells were significantly lower than healthy group(p<0.001), while the absolute numbers of Th17 cells increased(p=0.682). Th17/Treg was significantly higher than healthy group (p< 0.001). Cytokine analysis showed that the level of interleukin (IL)-4 in IRPF patients was higher than healthy group(p=0.011), IL-6, IL-10, IL-17, TNF-α and IFN-γ were significantly higher than healthy group (all p<0.001). Receiver operating characteristic (ROC) curves showed that IL-10 and TNF-α could distinguish bilateral ureteral dilatation in IRPF patients, with areas under the ROC curve (AUCs) of 0.813 (95% CI:0.607-1.000, p=0.026) and 0.950 (95% CI:0.856-1.000, p=0.001), respectively. IL-6 could distinguish bilateral ureteral obstruction, with an AUC of 0.861 (95% CI: 0.682-1.000, p=0.015).

Conclusions

Our study showed that IRPF patients had reduced Treg cells and indeed had Th17/Treg imbalance, which may be related to the pathogenesis of the disease. The levels of IL-6, IL-10 and TNF-α appear to be associated with the progression of IRPF.

Anti-Fibrotic Effect of SDF-1β Overexpression in Bleomycin-Injured Rat Lung

Rational: Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease and is associated with high mortality due to a lack of effective treatment. Excessive deposition of the extracellular matrix by activated myofibroblasts in the alveolar space leads to scar formation that hinders gas exchange. Therefore, selectively removing activated myofibroblasts with the aim to repair and remodel fibrotic lungs is a promising approach. Stromal-derived growth factor (SDF-1) is known to stimulate cellular signals which attract stem cells to the site of injury for tissue repair and remodeling. Here, we investigate the effect of overexpression of SDF-1β on lung structure using the bleomycin-injured rat lung model. Methods: Intratracheal administration of bleomycin was performed in adult male rats (F344). Seven days later, in vivo electroporation-mediated gene transfer of either SDF-1β or the empty vector was performed. Animals were sacrificed seven days after gene transfer and histology, design-based stereology, flow cytometry, and collagen measurement were performed on the tissue collected. For in vitro experiments, lung fibroblasts obtained from IPF patients were used. Results: Seven days after SDF-1β gene transfer to bleomycin-injured rat lungs, reduced total collagen, reduced collagen fibrils, improved histology and induced apoptosis of myofibroblasts were observed. Furthermore, it was revealed that TNF-α mediates SDF-1β-induced apoptosis of myofibroblasts; moreover, SDF-1β overexpression increased alveolar epithelial cell numbers and proliferation in vivo and also induced their migration in vitro. Conclusions: Our study demonstrates a new antifibrotic mechanism of SDF-1β overexpression and suggests SDF-1β as a potential new approach for the treatment of lung fibrosis.

Banti's Syndrome in an Adult Male: A Case Report

Banti’s syndrome is a chronic congestive enlargement of the spleen leading to the destruction of blood cells resulting in pancytopenia. It is also associated with cirrhosis and ascites along with symptoms of pancytopenia such as infection, bruising, weakness, and fatigue. Multiple factors such as hepatitis B infection, coagulation abnormalities and exposure to arsenic, etc. may also cause Banti’s syndrome. Clinical evaluation with blood profile along with use of imaging studies such as MRI and splenic venography is utilized for the determination of Banti’s syndrome. In this report, we present a 29-year-old diabetic male who presented with abdominal distention, right leg cellulitis, fever, and a past history of hematemesis and melena. On examination, distended abdomen showed marked splenomegaly with ascites (positive shifting dullness and fluid thrill). Also, the left leg was warm, swollen, and tender to the touch. Complete blood count showed decreased WBC, RBC, Hb, with peripheral smear negative for malarial parasites. Ultrasound scan of abdomen and pelvis was done illustrating massive splenomegaly with pelvic dilation and ascites.

Rheumatoid arthritis: Methods for two murine models

Rheumatoid arthritis is an incurable chronic inflammatory disease for which the pathophysiology is not fully understood, and treatment options are flawed. Thus, animal models are used to dissect disease pathogenesis and to develop improved therapeutics. However, accurately modeling all aspects of human rheumatoid arthritis in mice is not possible, and each model has pros and cons. Two useful murine models of rheumatoid arthritis are collagen induced arthritis and TNF induced arthritis. Both recapitulate the chronic inflammatory, erosive arthritis of human rheumatoid arthritis. Collagen induced arthritis has the added similarity to human rheumatoid arthritis of pathogenic autoantibodies, but can have variable degrees of arthritis severity, a challenge for experiments. In contrast, TNF induced arthritis tends to be uniform, but primarily models the innate arm of the immune response. Here we describe the benefits, limitations, and details for both models to help investigators select and implement an appropriate model to achieve the goals of their experiments.

Anti-fibrotic effect of adipose-derived stem cells on fibrotic scars

BACKGROUND

Sustained injury, through radiotherapy, burns or surgical trauma, can result in fibrosis, displaying an excessive deposition of extracellular matrix (ECM), persisting inflammatory reaction, and reduced vascularization. The increasing recognition of fibrosis as a cause for disease and mortality, and increasing use of radiotherapy causing fibrosis, stresses the importance of a decent anti-fibrotic treatment.

AIM

To obtain an in-depth understanding of the complex mechanisms underlying fibrosis, and more specifically, the potential mechanisms-of-action of adipose-derived stomal cells (ADSCs) in realizing their anti-fibrotic effect.

METHODS

A systematic review of the literature using PubMed, Embase and Web of Science was performed by two independent reviewers.

RESULTS

The injection of fat grafts into fibrotic tissue, releases ADSC into the environment. ADSCs’ capacity to directly differentiate into key cell types (e.g., ECs, fibroblasts), as well as to secrete multiple paracrine factors (e.g., hepatocyte growth factor, basis fibroblast growth factor, IL-10), allows them to alter different mechanisms underlying fibrosis in a combined approach. ADSCs favor ECM degradation by impacting the fibroblast-to-myofibroblast differentiation, favoring matrix metalloproteinases over tissue inhibitors of metalloproteinases, positively influencing collagen organization, and inhibiting the pro-fibrotic effects of transforming growth factor-β1. Furthermore, they impact elements of both the innate and adaptive immune response system, and stimulate angiogenesis on the site of injury (through secretion of pro-angiogenic cytokines like stromal cell-derived factor-1 and vascular endothelial growth factor).

CONCLUSION

This review shows that understanding the complex interactions of ECM accumulation, immune response and vascularization, is vital to fibrosis treatments’ effectiveness like fat grafting. It details how ADSCs intelligently steer this complex system in an anti-fibrotic or pro-angiogenic direction, without falling into extreme dilation or stimulation of a single aspect. Detailing this combined approach, has brought fat grafting one step closer to unlocking its full potential as a non-anecdotal treatment for fibrosis.

Advancing the Adverse Outcome Pathway for PPARγ Inactivation Leading to Pulmonary Fibrosis Using Bradford-Hill Consideration and the Comparative Toxicogenomics Database

Pulmonary fibrosis is regulated by transforming growth factor-β (TGF-β) and peroxisome proliferator-activated receptor-gamma (PPARγ). An adverse outcome pathway (AOP) for PPARγ inactivation leading to pulmonary fibrosis has been previously developed. To advance the development of this AOP, the confidence of the overall AOP was assessed using the Bradford-Hill considerations as per the recommendations from the Organisation for Economic Co-operation and Development (OECD) Users' Handbook. Overall, the essentiality of key events (KEs) and the biological plausibility of key event relationships (KERs) were rated high. In contrast, the empirical support of KERs was found to be moderate. To experimentally evaluate the KERs from the molecular initiating event (MIE) and KE1, PPARγ (MIE) and TGF-β (KE1) inhibitors were used to examine the effects of downstream events following inhibition of their upstream events. PPARγ inhibition (MIE) led to TGF-β activation (KE1), upregulation in vimentin expression (KE3), and an increase in the fibronectin level (KE4). Similarly, activated TGF-β (KE1) led to an increase in vimentin (KE3) and fibronectin expression (KE4). In the database analysis using the Comparative Toxicogenomics Database, 31 genes related to each KE were found to be highly correlated with pulmonary fibrosis, and the top 21 potential stressors were suggested. The AOP for pulmonary fibrosis evaluated in this study will be the basis for the screening of inhaled toxic substances in the environment.

Obesity and the Development of Lung Fibrosis

Obesity is an epidemic worldwide and the obese people suffer from a range of respiratory complications including fibrotic changes in the lung. The influence of obesity on the lung is multi-factorial, which is related to both mechanical injury and various inflammatory mediators produced by excessive adipose tissues, and infiltrated immune cells. Adiposity causes increased production of inflammatory mediators, for example, cytokines, chemokines, and adipokines, both locally and in the systemic circulation, thereby rendering susceptibility to respiratory diseases, and altered responses. Lung fibrosis is closely related to chronic inflammation in the lung. Current data suggest a link between lung fibrosis and diet-induced obesity, although the mechanism remains incomplete understood. This review summarizes findings on the association of lung fibrosis with obesity, highlights the role of several critical inflammatory mediators (e.g., TNF-α, TGF-β, and MCP-1) in obesity related lung fibrosis and the implication of obesity in the outcomes of idiopathic pulmonary fibrosis patients.

Mesenchymal Stromal Cells for the Treatment of Interstitial Lung Disease in Children: A Look from Pediatric and Pediatric Surgeon Viewpoints

Mesenchymal stromal cells (MSCs) have been proposed as a potential therapy to treat congenital and acquired lung diseases. Due to their tissue-regenerative, anti-fibrotic, and immunomodulatory properties, MSCs combined with other therapy or alone could be considered as a new approach for repair and regeneration of the lung during disease progression and/or after post- surgical injury. Children interstitial lung disease (chILD) represent highly heterogeneous rare respiratory diseases, with a wild range of age of onset and disease expression. The chILD is characterized by inflammatory and fibrotic changes of the pulmonary parenchyma, leading to gas exchange impairment and chronic respiratory failure associated with high morbidity and mortality. The therapeutic strategy is mainly based on the use of corticosteroids, hydroxychloroquine, azithromycin, and supportive care; however, the efficacy is variable, and their long-term use is associated with severe toxicity. The role of MSCs as treatment has been proposed in clinical and pre-clinical studies. In this narrative review, we report on the currently available on MSCs treatment as therapeutical strategy in chILD. The progress into the therapy of respiratory disease in children is mandatory to ameliorate the prognosis and to prevent the progression in adult age. Cell therapy may be a future therapy from both a pediatric and pediatric surgeon's point of view.

Pulmonary Complications of Pediatric Hematopoietic Cell Transplantation. A National Institutes of Health Workshop Summary

Approximately 2,500 pediatric hematopoietic cell transplants (HCTs), most of which are allogeneic, are performed annually in the United States for life-threatening malignant and nonmalignant conditions. Although HCT is undertaken with curative intent, post-HCT complications limit successful outcomes, with pulmonary dysfunction representing the leading cause of nonrelapse mortality. To better understand, predict, prevent, and/or treat pulmonary complications after HCT, a multidisciplinary group of 33 experts met in a 2-day National Institutes of Health Workshop to identify knowledge gaps and research strategies most likely to improve outcomes. This summary of Workshop deliberations outlines the consensus focus areas for future research.

Tumor microenvironment and radioresistance

Metastasis is not the result of a random event, as cancer cells can sustain and proliferate actively only in a suitable tissue microenvironment and then form metastases. Since Dr. Stephen Paget in the United Kingdom proposed the seed and soil hypothesis of cancer metastasis based on the analogy that plant seeds germinate and grow only in appropriate soil, considerable attention has focused on both extracellular environmental factors that affect the growth of cancer cells and the tissue structure that influences the microenvironment. Malignant tumor tissues consist of not only cancer cells but also a wide variety of other cells responsible for the inflammatory response, formation of blood vessels, immune response, and support of the tumor tissue architecture, forming a complex cellular society. It is also known that the amounts of oxygen and nutrients supplied to each cell differ depending on the distance from tumor blood vessels in tumor tissue. Here, we provide an overview of the tumor microenvironment and characteristics of tumor tissues, both of which affect the malignant phenotypes and radioresistance of cancer cells, focusing on the following keywords: diversity of oxygen and nutrient microenvironment in tumor tissue, inflammation, immunity, and tumor vasculature.

Preclinical MRI to Quantify Pulmonary Disease Severity and Trajectories in Poorly Characterized Mouse Models: A Pedagogical Example Using Data from Novel Transgenic Models of Lung Fibrosis

Structural remodeling in lung disease is progressive and heterogeneous, making temporally and spatially explicit information necessary to understand disease initiation and progression. While mouse models are essential to elucidate mechanistic pathways underlying disease, the experimental tools commonly available to quantify lung disease burden are typically invasive (e.g., histology). This necessitates large cross-sectional studies with terminal endpoints, which increases experimental complexity and expense. Alternatively, magnetic resonance imaging (MRI) provides information noninvasively, thus permitting robust, repeated-measures statistics. Although lung MRI is challenging due to low tissue density and rapid apparent transverse relaxation (T₂* <1 ms), various imaging methods have been proposed to quantify disease burden. However, there are no widely accepted strategies for preclinical lung MRI. As such, it can be difficult for researchers who lack lung imaging expertise to design experimental protocols-particularly for novel mouse models. Here, we build upon prior work from several research groups to describe a widely applicable acquisition and analysis pipeline that can be implemented without prior preclinical pulmonary MRI experience. Our approach utilizes 3D radial ultrashort echo time (UTE) MRI with retrospective gating and lung segmentation is facilitated with a deep-learning algorithm. This pipeline was deployed to assess disease dynamics over 255 days in novel, transgenic mouse models of lung fibrosis based on disease-associated, loss-of-function mutations in Surfactant Protein-C. Previously identified imaging biomarkers (tidal volume, signal coefficient of variation, etc.) were calculated semi-automatically from these data, with an objectively-defined high signal volume identified as the most robust metric. Beyond quantifying disease dynamics, we discuss common pitfalls encountered in preclinical lung MRI and present systematic approaches to identify and mitigate these challenges. While the experimental results and specific pedagogical examples are confined to lung fibrosis, the tools and approaches presented should be broadly useful to quantify structural lung disease in a wide range of mouse models.

Beneficial impact of cathelicidin on hypersensitivity pneumonitis treatment-In vivo studies

Cathelicidin (CRAMP) is a defence peptide with a wide range of biological responses including antimicrobial, immunomodulatory and wound healing. Due to its original properties the usefulness of CRAMP in the treatment of pulmonary fibrosis was assessed in a murine model of hypersensitivity pneumonitis (HP). The studies were conducted on mouse strain C57BL/6J exposed to a saline extract of Pantoea agglomerans cells (HP inducer). Cathelicidin was administered in the form of an aerosol during and after HP development. Changes in the composition of immune cell populations (NK cells, macrophages, lymphocytes: Tc, Th, Treg, B), were monitored in lung tissue by flow cytometry. Extracellular matrix deposition (collagens, hydroxyproline), the concentration of cytokines involved in inflammatory and the fibrosis process (IFNγ, TNFα, TGFβ1, IL1β, IL4, IL5, IL10, IL12α, IL13) were examined in lung homogenates by the ELISA method. Alterations in lung tissue morphology were examined in mouse lung sections stained with haematoxylin and eosin as well as Masson trichrome dyes. The performed studies revealed that cathelicidin did not cause any negative changes in lung morphology/structure, immune cell composition or cytokines production. At the same time, CRAMP attenuated the immune reaction induced by mice chronic exposure to P. agglomerans and inhibited hydroxyproline and collagen deposition in the lung tissue of mice treated with bacteria extract. The beneficial effect of CRAMP on HP treatment was associated with restoring the balance in quantity of immune cells, cytokines production and synthesis of extracellular matrix components. The presented study suggests the usefulness of cathelicidin in preventing lung fibrosis; however, cathelicidin was not able to reverse pathological changes completely.

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.

Interstitial Score and Concentrations of IL-4Rα, PAR-2, and MMP-7 in Bronchoalveolar Lavage Fluid Could Be Useful Markers for Distinguishing Idiopathic Interstitial Pneumonias

Idiopathic interstitial pneumonia (IIP) entails a variable group of lung diseases of unknown etiology. Idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, interstitial lung diseases related to connective tissue disease (CTD-ILD), and hypersensitivity pneumonitis (HP) can manifest with similar clinical, radiological, and histopathological features. In a differential diagnosis, biomarkers can play a significant role. We assume that levels of specific cyto- or chemokines or their receptors can signal pathogenetic processes in the lungs. Eighty patients with different types of idiopathic interstitial pneumonia were enrolled in this study. Cell counts and concentrations of tumor necrosis factor (TNF)-α, interleukin-4 receptor α, proteinase-activated receptor (PAR)-2, matrix metalloproteinase (MMP)-7, and B cell-activating factor were measured in bronchoalveolar lavage fluid using commercial ELISA kits. High resolution computer tomography results were evaluated using alveolar and interstitial (IS) score scales. Levels of TNF-α were significantly higher in HP compared to fibrosing IIP (p < 0.0001) and CTD-ILD (p = 0.0381). Concentrations of IL-4Rα, PAR-2, and MMP-7 were positively correlated with IS (p = 0.0009; p = 0.0256; p = 0.0015, respectively). Since TNF-α plays a major role in inflammation, our results suggest that HP is predominantly an inflammatory disease. From the positive correlation with IS we believe that IL-4Rα, PAR-2, and MMP-7 could serve as fibroproliferative biomarkers in differential diagnosis of IIP.

Twist1 in T Lymphocytes Augments Kidney Fibrosis after Ureteral Obstruction

Background

Twist1 is a basic helix-loop-helix domain-containing transcription factor that participates in diverse cellular functions, including epithelial-mesenchymal transition and the cellular immune response. Although Twist1 plays critical roles in the initiation and progression of kidney diseases, the effects of Twist1 in the T lymphocyte on the progression of renal fibrosis require elucidation.

Methods

129/SvEv mice with a floxed allele for the gene encoding Twist1 or TNFα were bred with CD4-Cre mice to yield CD4-Cre⁺ Twist1^flox/flox (Twist1-TKO) or CD4-Cre⁺ TNF^flox/flox (TNF-TKO) mice with robust, but selective, deletion of Twist1 or TNFα mRNA in T cells, respectively. Twist1 TKO, TNF TKO, and WT controls underwent UUO with assessment of kidney fibrosis and T-cell phenotype at 14 days.

Results

Compared with WT controls, obstructed kidneys from Twist1 TKO mice had attenuated extracellular matrix deposition. Despite this diminished fibrosis, Twist1 TKO obstructed kidneys contained more CD8⁺ T cells than in WTs. These intrarenal CD8⁺ T cells exhibited greater activation and higher levels of TNFα expression than those from WT obstructed kidneys. Further, we found that selective deletion of TNFα from T cells exaggerated renal scar formation and injury after UUO, highlighting the capacity of T-cell TNF to constrain fibrosis in the kidney.

Conclusions

Twist1 in T cells promotes kidney fibrogenesis, in part, by curtailing the renal accumulation of TNF-elaborating T cells.

Increased sensitivity to TNF-α promotes keloid fibroblast hyperproliferation by activating the NF-κB, JNK and p38 MAPK pathways

Hyperproliferation of fibroblasts is the main cause of keloid formation. However, the pathogenesis of keloids has yet to be fully elucidated. Tumor necrosis factor (TNF)-α may play an important role in the formation and proliferation of keloids, as it is implicated in the pathogenesis of various fibrous disorders. In the present study, the expression level of TNF-α and its receptors, soluble TNF receptor (sTNFR)1 and sTNFR2, in the peripheral blood and skin tissues was detected by ELISA, reverse transcription-quantitative PCR or immunohistochemistry. There was no statistically significant difference in the expression of TNF-α and sTNFR2 in the peripheral blood and skin tissues between patients with keloids and healthy participants (P>0.05), while the sTNFR1 mRNA level in fibroblasts cultured in vitro and its protein level in keloid skin samples were significantly higher compared with those in normal skin (P<0.05). Subsequently, TNF-α recombinant protein was used to treat keloid-derived and normal skin fibroblasts, and it was observed that TNF-α promoted the proliferation of keloid fibroblasts (KFs), but had little effect on normal skin fibroblasts. Furthermore, it was observed that TNF-α stimulation led to the activation of the nuclear factor (NF)-κB, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) pathways in KFs. In conclusion, KFs exhibited increased expression of sTNFR1, which may contribute to the increased sensitivity to TNF-α, resulting in low concentrations of TNF-α activating the NF-κB, JNK and p38 MAPK pathways, thereby promoting the sustained and excessive proliferation of KFs.

Emerging cellular and molecular determinants of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF), the most common form of idiopathic interstitial pneumonia, is a progressive, irreversible, and typically lethal disease characterized by an abnormal fibrotic response involving vast areas of the lungs. Given the poor knowledge of the mechanisms underpinning IPF onset and progression, a better understanding of the cellular processes and molecular pathways involved is essential for the development of effective therapies, currently lacking. Besides a number of established IPF-associated risk factors, such as cigarette smoking, environmental factors, comorbidities, and viral infections, several other processes have been linked with this devastating disease. Apoptosis, senescence, epithelial-mesenchymal transition, endothelial-mesenchymal transition, and epithelial cell migration have been shown to play a key role in IPF-associated tissue remodeling. Moreover, molecules, such as chemokines, cytokines, growth factors, adenosine, glycosaminoglycans, non-coding RNAs, and cellular processes including oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, hypoxia, and alternative polyadenylation have been linked with IPF development. Importantly, strategies targeting these processes have been investigated to modulate abnormal cellular phenotypes and maintain tissue homeostasis in the lung. This review provides an update regarding the emerging cellular and molecular mechanisms involved in the onset and progression of IPF.

The protective effects of granulocyte-macrophage colony-stimulating factor against radiation-induced lung injury

Background

Radiation-induced lung injury (RILI) is a common complication of thoracic cancer radiation therapy. Currently, there is no effective treatment for RILI. RILI is associated with chronic inflammation, this injury is perpetuated by the stimulation of chemokines and proinflammatory cytokines. Recent studies have demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) plays a pivotal role in inflammation and fibrosis. This study aimed to investigate the protective effect of GM-CSF against the development of RILI in lung tissue.

Method

First, a single fraction of radiation at a dose of 16 Gy was targeted at the entire thorax of wild-type (WT) C57BL/6 mice and GM-CSF^–/– mice to induce RILI. Second, we detected the radioprotective effects of GM-CSF by measuring the inflammatory biomarkers and fibrosis alteration on radiated lung tissues. Furthermore, we investigated the potential mechanism of GM-CSF protective effects in RILI.

Results

The GM-CSF^–/– mice sustained more severe RILI than the WT mice. RILI was significantly alleviated by GM-CSF treatment. Intraperitoneally administered GM-CSF significantly inhibited inflammatory cytokine production and decreased epithelial-mesenchymal transition (EMT) in the RILI mouse model.

Conclusions

GM-CSF was shown to be an important modulator of RILI through regulating inflammatory cytokines, which provides a new strategy for the prevention and treatment of RILI.

Molecular and Clinical Features of EGFR-TKI-Associated Lung Injury

The tyrosine kinase activity of epidermal growth factor receptors (EGFRs) plays critical roles in cell proliferation, regeneration, tumorigenesis, and anticancer resistance. Non-small-cell lung cancer patients who responded to EGFR-tyrosine kinase inhibitors (EGFR-TKIs) and obtained survival benefits had somatic EGFR mutations. EGFR-TKI-related adverse events (AEs) are usually tolerable and manageable, although serious AEs, including lung injury (specifically, interstitial lung disease (ILD), causing 58% of EGFR-TKI treatment-related deaths), occur infrequently. The etiopathogenesis of EGFR-TKI-induced ILD remains unknown. Risk factors, such as tobacco exposure, pre-existing lung fibrosis, chronic obstructive pulmonary disease, and poor performance status, indicate that lung inflammatory circumstances may worsen with EGFR-TKI treatment because of impaired epithelial healing of lung injuries. There is limited evidence from preclinical and clinical studies of the mechanisms underlying EGFR-TKI-induced ILD in the available literature. Herein, we evaluated the relationship between EGFR-TKIs and AEs, especially ILD. Recent reports on mechanisms inducing lung injury or resistance in cytokine-rich circumstances were reviewed. We discussed the relevance of cytotoxic agents or immunotherapeutic agents in combination with EGFR-TKIs as a potential mechanism of EGFR-TKI-related lung injury and reviewed recent developments in diagnostics and therapeutics that facilitate recovery from lung injury or overcoming resistance to anti-EGFR treatment.

SARS-CoV-2, immunosenescence and inflammaging: partners in the COVID-19 crime

Pneumonia outbreak in the city of Wuhan, China, prompted the finding of a novel strain of severe acute respiratory syndrome virus (SARS-CoV-2). Here, we discuss potential long-term consequences of SARS-CoV-2 infection, and its possibility to cause permanent damage to the immune system and the central nervous system. Advanced chronological age is one of the main risk factors for the adverse outcomes of COVID-19, presumably due to immunosenescence and chronic low-grade inflammation, both characteristic of the elderly. The combination of viral infection and chronic inflammation in advanced chronological age might cause multiple detrimental unforeseen consequences for the predisposition and severity of neurodegenerative diseases and needs to be considered so that we can be prepared to deal with future outcomes of the ongoing pandemic.

Current models of pulmonary fibrosis for future drug discovery efforts

INTRODUCTION

Pulmonary fibrosis includes several lung disorders characterized by progressive fibrosis, of which idiopathic pulmonary fibrosis (IPF) is a particularly severe form with a median survival time of 3-5 years after diagnosis. Although numerous compounds have shown efficacy in attenuating pulmonary fibrosis using animal models, only a few compounds have shown their beneficial effects for IPF in clinical trials. Thus, there is an emergent need to improve the preclinical development process to better identify, characterize and select clinically useful targets.

AREAS COVERED

In this review, the authors extensively describe current models of pulmonary fibrosis, including rodent models, ex vivo models, and in vitro models.

EXPERT OPINION

Based upon our current understanding, improving the identification and characterization of clinically relevant molecules or pathways responsible for progressive fibrotic diseases and use of the appropriate preclinical model system to test these will likely be required to improve the drug development pipeline for pulmonary fibrosis. Combination with appropriate preclinical models with ex vivo (precision-cut lung slices) or in vitro models would be beneficial for high-throughput drug discovery or validation of drug effects.

Reinterpreting Evidence of Rheumatoid Arthritis-Associated Interstitial Lung Disease to Understand Etiology

Interstitial Lung Disease (ILD) is a well-known complication of rheumatoid arthritis (RA) which often results in significant morbidity and mortality. It is often diagnosed late in the disease process via descriptive criteria. Multiple subtypes of RA-ILD exist as defined by chest CT and histopathology. In the absence of formal natural history studies and definitive diagnostics, a conventional dogma has emerged that there are two major subtypes of RA-ILD (nonspecific interstitial pneumonia (NSIP) and Usual Interstitial Pneumonia (UIP)). These subtypes are based on clinical experience and correlation studies. However, recent animal model data are incongruous with established paradigms of RA-ILD and beg reassessment of the clinical evidence in order to better understand etiology, pathogenesis, prognosis, and response to therapy. To this end, here we: 1) review the literature on epidemiology, radiology, histopathology and clinical outcomes of the various RAILD subtypes, existing animal models, and current theories on RA-ILD pathogenesis; 2) highlight the major gaps in our knowledge; and 3) propose future research to test an emerging theory of RAILD that posits initial rheumatic lung inflammation in the form of NSIP-like pathology transforms mesenchymal cells to derive chimeric disease, and subsequently develops into frank UIP-like fibrosis in some RA patients. Elucidation of the pathogenesis of RA-ILD is critical for the development of effective interventions for RA-ILD.

Gene therapy-emulating small molecule treatments in cystic fibrosis airway epithelial cells and patients

Background

Several small molecule corrector and potentiator drugs have recently been licensed for Cystic Fibrosis (CF) therapy. However, other aspects of the disease, especially inflammation, are less effectively treated by these drugs. We hypothesized that small molecule drugs could function either alone or as an adjuvant to licensed therapies to treat these aspects of the disease, perhaps emulating the effects of gene therapy in CF cells. The cardiac glycoside digitoxin, which has been shown to inhibit TNFα/NFκB signaling in CF lung epithelial cells, may serve as such a therapy.

Methods

IB3–1 CF lung epithelial cells were treated with different Vertex (VX) drugs, digitoxin, and various drug mixtures, and ELISA assays were used to assess suppression of baseline and TNFα-activated secretion of cytokines and chemokines. Transcriptional responses to these drugs were assessed by RNA-seq and compared with gene expression in AAV-[wildtype]CFTR-treated IB3–1 (S9) cells. We also compared in vitro gene expression signatures with in vivo data from biopsied nasal epithelial cells from digitoxin-treated CF patients.

Results

CF cells exposed to digitoxin exhibited significant suppression of both TNFα/NFκB signaling and downstream secretion of IL-8, IL-6 and GM-CSF, with or without co-treatment with VX drugs. No evidence of drug-drug interference was observed. RNA-seq analysis showed that gene therapy-treated CF lung cells induced changes in 3134 genes. Among these, 32.6% were altered by digitoxin treatment in the same direction. Shared functional gene ontology themes for genes suppressed by both digitoxin and gene therapy included inflammation (84 gene signature), and cell-cell interactions and fibrosis (49 gene signature), while genes elevated by both were enriched for epithelial differentiation (82 gene signature). A new analysis of mRNA data from digitoxin-treated CF patients showed consistent trends in expression for genes in these signatures.

Conclusions

Adjuvant gene therapy-emulating activities of digitoxin may contribute to enhancing the efficacy of currently licensed correctors and potentiators in CF patients.

TNF-Induced Interstitial Lung Disease in a Murine Arthritis Model: Accumulation of Activated Monocytes, Conventional Dendritic Cells, and CD21+/CD23- B Cell Follicles Is Prevented with Anti-TNF Therapy

Interstitial lung disease (ILD) is a well-known extra-articular manifestation of rheumatoid arthritis (RA). RA-associated ILD (RA-ILD) exists on a wide spectrum, with variable levels of inflammatory and fibrotic activity, although all subtypes are regarded as irreversible pathologic conditions. In both articular and pulmonary manifestations, TNF is a significant pathogenic factor. Whereas anti-TNF therapy alleviates joint pathologic conditions, it exacerbates fibrotic RA-ILD. The TNF-transgenic (TNF-Tg) murine model of RA develops both inflammatory arthritis and an ILD that mimics a cellular nonspecific interstitial pneumonia pattern dominated by an interstitial accumulation of inflammatory cells with minimal-to-absent fibrosis. Given the model's potential to elucidate the genesis of inflammatory RA-ILD, we aim to achieve the following: 1) characterize the cellular accumulations in TNF-Tg lungs, and 2) assess the reversibility of inflammatory ILD following anti-TNF therapy known to resolve TNF-Tg inflammatory arthritis. TNF-Tg mice with established disease were randomized to anti-TNF or placebo therapy and evaluated with imaging, histology, and flow cytometric analyses, together with wild-type controls. Flow cytometry of TNF-Tg versus wild-type lungs revealed significant increases in activated monocytes, conventional dendritic cells, and CD21+/CD23- B cells that are phenotypically distinct from the B cells in inflamed nodes, which are known to accumulate in joint-draining lymph nodes. In contrast to human RA-ILD, anti-TNF treatment significantly alleviated both joint and lung inflammation. These results identify a potential role for activated monocytes, conventional dendritic cells, and CD21+/CD23- B cells in the genesis of RA-ILD, which exist in a previously unknown, reversible, prefibrotic stage of the disease.

Pirfenidone activates cannabinoid receptor 2 in a mouse model of bleomycin-induced pulmonary fibrosis

Inflammation serves an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Cannabinoid receptor 2 (CB2R) is a receptor predominantly expressed in the immune system. CB2R agonists can be used to treat a wide range of inflammation-related diseases. Pirfenidone has been demonstrated to be effective for IPF treatment. The aim of present study was to investigate whether CB2R activation mediates the antifibrotic effect of pirfenidone. For that purpose, mice were intravenously injected with bleomycin (BLM; 5 mg/kg/day). pirfenidone (300 mg/kg/day) was then orally administered for 15 days. Lung pathological alterations in the mice were evaluated by Masson's trichrome staining. The mRNA and protein levels of CB2R in lung tissues were measured by reverse transcription-quantitative PCR and western blotting. The levels of inflammatory factors were determined by ELISA. The effect of pirfenidone on WI38 cell viability was evaluated by MTT assay. The results demonstrated that CB2R protein and mRNA levels increased with increasing fibrosis in mice with BLM-induced IPF. Pirfenidone administration significantly ameliorated IPF and reduced the serum levels of inflammatory factors induced by BLM. Pirfenidone also inhibited fibroblast cell proliferation and decreased the levels of inflammatory factors in vitro, which could be reversed by the CB2R antagonist SR144528, suggesting that CB2R was activated by pirfenidone. In conclusion, pirfenidone attenuated and activated CB2R in BLM-treated mice. In addition, pirfenidone inhibited fibroblast cell proliferation in vitro. These effects could be reversed by the CB2R antagonist SR144528. Thus, activation of CB2R may be considered a mechanism of the antifibrotic effects of pirfenidone.

Restrictive lung disease in TNF-transgenic mice: correlation of pulmonary function testing and micro-CT imaging

Purpose: Micro-computed tomography (µCT) is increasingly being used on animal models as a minimally-invasive longitudinal outcome measure of pulmonary disease progression. However, while imaging can elucidate macroscopic structural changes over the whole lung, µCT is unable to describe the mechanical changes and functional impairments imposed by progressive disease, which can only be measured via pulmonary function tests (PFTs). The tumor necrosis factor-transgenic (TNF-Tg) mouse model of rheumatoid arthritis (RA) develops pulmonary pathology that mimics many aspects of the inflammatory interstitial lung disease (ILD) seen in a subset of patients with RA. Prior studies using µCT imaging of these mice found increased pulmonary density, characteristic of restrictive disease; however, there have been conflicting reports in the literature regarding the obstructive versus restrictive phenotype of this model. Our study looks to 1) define the functional impairments and 2) characterize the restrictive/obstructive nature of the disease found in this model. Materials and Methods: In this study, we performed PFTs at end-stage ILD, and paired these findings with µCT results, correlating radiology to functional parameters. TNF-Tg and WT littermates of both sexes underwent µCT imaging and PFT testing at 5.5 months-old. Spearman's correlation analyses were performed comparing lung tissue volume (LTV) to PFT parameters of gas exchange and tissue stiffness. Results: Compared to WT, TNF-Tg mice had impaired gas exchange capacity, increased respiratory resistance, and reduced lung compliance, elastance, and inspiratory capacity, indicating increased tissue stiffness and compromised pulmonary function. LTV was also consistently higher in TNF-Tg lungs. Conclusions: These findings demonstrate that: 1) TNF-Tg mice display a restrictive pathology, and 2) in vivo µCT is a valid outcome measure to infer changes in pulmonary mechanical and functional parameters.

Blockade of EGFR Activation Promotes TNF-Induced Lung Epithelial Cell Apoptosis and Pulmonary Injury

Pneumonitis is the leading cause of death associated with the use of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs) against non-small cell lung cancer (NSCLC). However, the risk factors and the mechanism underlying this toxicity have not been elucidated. Tumor necrosis factor (TNF) has been reported to transactivate EGFR in pulmonary epithelial cells. Hence, we aimed to test the hypothesis that EGFR tyrosine kinase activity regulates TNF-mediated bronchial epithelial cell survival, and that inhibition of EGFR activity increases TNF-induced lung epithelial cell apoptosis. We used surfactant protein C (SPC)-TNF transgenic (tg) mice which overexpress TNF in the lungs. In this model, gefitinib, an EGFR-TKI, enhanced lung epithelial cell apoptosis and lymphocytic inflammation, indicating that EGFR tyrosine kinase prevents TNF-induced lung injury. Furthermore, IL-17A was significantly upregulated by gefitinib in SPC-TNF tg mice and p38MAPK activation was observed, indicative of a pathway involved in lung epithelial cell apoptosis. Moreover, in lung epithelial cells, BEAS-2B, TNF stimulated EGFR transactivation via the TNF-α-converting enzyme in a manner that requires heparin binding (HB)-EGF and transforming growth factor (TGF)-α. These novel findings have significant implications in understanding the role of EGFR in maintaining human bronchial epithelial cell homeostasis and in NSCLC treatment.

N-acetylcysteine tiherapeutically protects against pulmonary fibrosis in a mouse model of silicosis

Silicosis is a lethal pneumoconiosis disease characterized by chronic lung inflammation and fibrosis. The present study was to explore the effect of against crystalline silica (CS)-induced pulmonary fibrosis. A total of 138 wild-type C57BL/6J mice were divided into control and experimental groups, and killed on month 0, 1, 2, 3, 4, and 5. Different doses of N-acetylcysteine (NAC) were gavaged to the mice after CS instillation to observe the effect of NAC on CS induced pulmonary fibrosis and inflammation. The pulmonary injury was evaluated with Hematoxylin and eosin/Masson staining. Reactive oxygen species level was analyzed by DCFH-DA labeling. Commercial ELISA kits were used to determine antioxidant activity (T-AOC, glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) and cytokines (TNF-α, IL-1β, IL-4, and IL-6). The expression of oxidising enzymes (NOX2, iNOS, SOD2, and XO) were detected by real time PCR. Immunohistochemistry (IHC) staining was performed to examine epithelial-mesenchymal transition-related markers. The mice treated with NAC presented markedly reduced CS-induced pulmonary injury and ameliorated CS-induced pulmonary fibrosis and inflammation. The level of malondialdehyde was reduced, while the activities of GSH-PX, SOD, and T-AOC were markedly enhanced by NAC. We also found the down-regulation of oxidising enzymes (NOX2, iNOS, SOD2, and XO) after NAC treatment. Moreover, E-cadherin expression was increased while vimentin and Cytochrome C expressions were decreased by NAC. These encouraging findings suggest that NAC exerts pulmonary protective effects in CS-induced pulmonary fibrosis and might be considered as a promising agent for the treatment of silicosis.

Mouse pulmonary response to dust from sawing Corian®, a solid-surface composite material

Corian®, a solid-surface composite (SSC), is composed of alumina trihydrate and acrylic polymer. The aim of the present study was to examine the pulmonary toxicity attributed to exposure to SSC sawing dust. Male mice were exposed to either phosphate buffer saline (PBS, control), 62.5, 125, 250, 500, or 1000 µg of SSC dust, or 1000 µg silica (positive control) via oropharyngeal aspiration. Body weights were measured for the duration of the study. Bronchoalveolar lavage fluid (BALF) and tissues were collected for analysis at 1 and 14 days post-exposure. Enhanced-darkfield and histopathologic analysis was performed to assess particle distribution and inflammatory responses. BALF cells and inflammatory cytokines were measured. The geometric mean diameter of SSC sawing dust following suspension in PBS was 1.25 µm. BALF analysis indicated that lactate dehydrogenase (LDH) activity, inflammatory cells, and pro-inflammatory cytokines were significantly elevated in the 500 and 1000 µg SSC exposure groups at days 1 and 14, suggesting that exposure to these concentrations of SSC induced inflammatory responses, in some cases to a greater degree than the silica positive control. Histopathology indicated the presence of acute alveolitis at all doses at day 1, which was largely resolved by day 14. Alveolar particle deposition and granulomatous mass formation were observed in all exposure groups at day 14. The SSC particles were poorly cleared, with 81% remaining at the end of the observation period. These findings demonstrate that SSC sawing dust exposure induces pulmonary inflammation and damage that warrants further investigation. Abbreviations: ANOVA: Analysis of Variance; ATH: Alumina Trihydrate; BALF: Bronchoalveolar Lavage Fluid; D_pg: Geometric Mean Diameter; FE-SEM: Field Emission Scanning Electron Microscopy; IACUC: Institutional Animal Care and Use Committee; IFN-γ: Interferon Gamma; IL-1 Β: Interleukin-1 Beta; IL-10: Interleukin-10; IL-12: Interleukin-12; IL-2: Interleukin-2; IL-4: Interleukin-4; IL-5: Interleukin-5; IL-6: Interleukin-6; KC/GRO: Neutrophil-Activating Protein 3; MMAD: Mass Median Aerodynamic Diameter; PBS: Phosphate-Buffered Saline; PEL: Permissible Exposure Limit; PM: Polymorphonuclear Leukocytes; PNOR: Particles Not Otherwise Regulated; SEM/EDX: Scanning Electron Microscope/Energy-Dispersive X-Ray; SSA: Specific Surface Area; SSC: Solid Surface Composite; TNFα: Tumor Necrosis Factor-Alpha; VOC: Volatile Organic Compounds; σ_g: Geometric Standard Deviation.

Pomalidomide Reduces Ischemic Brain Injury in Rodents

Stroke is a leading cause of death and severe disability worldwide. After cerebral ischemia, inflammation plays a central role in the development of permanent neurological damage. Reactive oxygen species (ROS) are involved in the mechanism of post-ischemic inflammation. The activation of several inflammatory enzymes produces ROS, which subsequently suppress mitochondrial activity, leading to further tissue damage. Pomalidomide (POM) is a clinically available immunomodulatory and anti-inflammatory agent. Prior cellular studies demonstrate that POM can mitigate oxidative stress and lower levels of pro-inflammatory cytokines, particularly TNF-α, which plays a prominent role in ischemic stroke-induced brain damage and functional deficits. To evaluate the potential value of POM in cerebral ischemia, POM was initially administered to transgenic mice chronically over-expressing TNF-α surfactant protein (SP)-C promoter (SP-C/TNF-α mice) to assess whether systemically administered drug could lower systemic TNF-α level. POM significantly lowered serum levels of TNF-α and IL-5. Pharmacokinetic studies were then undertaken in mice to evaluate brain POM levels following systemic drug administration. POM possessed a brain/plasma concentration ratio of 0.71. Finally, rats were subjected to transient middle cerebral artery occlusion (MCAo) for 60 min, and subsequently treated with POM 30 min thereafter to evaluate action on cerebral ischemia. POM reduced the cerebral infarct volume in MCAo-challenged rats and improved motor activity, as evaluated by the elevated body swing test. POM’s neuroprotective actions on ischemic injury represent a potential therapeutic approach for ischemic brain damage and related disorders, and warrant further evaluation.

Tumor necrosis factor gene polymorphisms are associated with silicosis: a systemic review and meta-analysis

Studies investigating association between tumor necrosis factor (TNF) gene polymorphisms and silicosis susceptibility report conflicting results. The aim of this meta-analysis was to assess association between TNF gene polymorphisms and silicosis susceptibility. A systematic literature search was conducted to find relevant studies. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of association. Finally, a total of 12 articles, involving 1990 silicosis patients and 1898 healthy controls were included in the meta-analysis. Overall, meta-analysis revealed a significant association between the TNF −308A allele and silicosis (OR = 1.348, 95%CI = 1.156–1.570, P<0.001). A significant association of AA+AG genotype of the TNF −308 A/G polymorphism with susceptibility to silicosis was also found (OR = 1.466, 95%CI = 1.226–1.753, P<0.001). After stratification by ethnicity, significant associations were detected under the genetic models (A allele and AA+AG genotype) for TNF −308A/G polymorphisms in the Asian population (P<0.05). Similarly, meta-analysis of the TNF −238A/G polymorphism revealed the same pattern as that shown by meta-analysis of TNF −308A/G. The meta-analysis suggests that the TNF −308A/G and −238A/G polymorphisms are associated with susceptibility to silicosis, especially in Asians.

Protective effect of cysteinyl leukotriene receptor antagonist montelukast in bleomycin-induced pulmonary fibrosis

Background

This study aims to investigate the early- and late-term effects of pharmacological inhibition of cysteinyl leukotriene activity by using montelukast in bleomycin-induced inflammatory and oxidative lung injury in an animal model.

Methods

The study included 48 male Wistar albino rats (weighing 250 g to 300 g). Rats were administered intratracheal bleomycin or saline and assigned into groups to receive montelukast or saline. Bronchoalveolar lavage fluid and lung tissue samples were collected four and 15 days after bleomycin administration.

Results

Bleomycin resulted in significant increases in tumor necrosis factor-alpha levels (4.0±1.4 pg/mL in controls vs. 44.1±14.5 pg/mL in early-term vs. 30.3±5.7 pg/mL in late-term, p<0.001 and p<0.001, respectively), transforming growth factor beta 1 levels (28.6±6.6 pg/mL vs. 82.3±14.1 pg/mL in early-term vs. 60.1±2.9 pg/mL in late-term, p<0.001 and p<0.001, respectively), and fibrosis score (1.85±0.89 in early-term vs. 5.60±1.14 in late-term, p<0.001 and p<0.01, respectively). In bleomycin exposed rats, collagen content increased only in the late-term (15.3±3.0 ?g/mg in controls vs. 29.6±9.1 ?g/mg in late-term, p<0.001). Montelukast treatment reversed all these biochemical indices as well as histopathological alterations induced by bleomycin.

Conclusion

Montelukast attenuates bleomycin-induced inflammatory and oxidative lung injury and prevents lung collagen deposition and fibrotic response. Thus, cysteinyl leukotriene receptor antagonists might be regarded as new therapeutic agents for idiopathic pulmonary fibrosis.

Longitudinal micro-CT as an outcome measure of interstitial lung disease in TNF-transgenic mice

INTRODUCTION

Rheumatoid arthritis associated interstitial lung disease (RA-ILD) is a debilitating condition with poor survival prognosis. High resolution computed tomography (CT) is a common clinical tool to diagnose RA-ILD, and is increasingly being adopted in pre-clinical studies. However, murine models recapitulating RA-ILD are lacking, and CT outcomes for inflammatory lung disease have yet to be formally validated. To address this, we validate μCT outcomes for ILD in the tumor necrosis factor transgenic (TNF-Tg) mouse model of RA.

METHODS

Cross sectional μCT was performed on cohorts of male TNF-Tg mice and their WT littermates at 3, 4, 5.5 and 12 months of age (n = 4-6). Lung μCT outcomes measures were determined by segmentation of the μCT datasets to generate Aerated and Tissue volumes. After each scan, lungs were obtained for histopathology and 3 sections stained with hematoxylin and eosin. Automated histomorphometry was performed to quantify the tissue area (nuclei, cytoplasm, and extracellular matrix) and aerated area (white space) within the tissue sections. Spearman's correlation coefficients were used to evaluate the extent of association between μCT imaging and histopathology endpoints.

RESULTS

TNF-Tg mice had significantly greater tissue volume, total lung volume and mean intensity at all timepoints compared to age matched WT littermates. Histomorphometry also demonstrated a significant increase in tissue area at 3, 4, and 5.5 months of age in TNF-Tg mice. Lung tissue volume was correlated with lung tissue area (ρ = 0.81, p<0.0001), and normalize lung aerated volume was correlated with normalized lung air area (ρ = 0.73, p<0.0001).

CONCLUSIONS

We have validated in vivo μCT as a quantitative biomarker of ILD in mice. Further, development of longitudinal measures is critical for dissecting pathologic progression of ILD, and μCT is a useful non-invasive method to study lung inflammation in the TNF-Tg mouse model.

Lung fibrosis-associated soluble mediators and bronchoalveolar lavage from idiopathic pulmonary fibrosis patients promote the expression of fibrogenic factors in subepithelial lung myofibroblasts

Idiopathic pulmonary fibrosis (IPF) is characterized by infiltration of inflammatory cells, excessive collagen production and accumulation of myofibroblasts. We explored the possible role of subepithelial lung myofibroblasts (SELMs) in the development of fibrosis in IPF. SELMs, isolated from surgical specimens of healthy lung tissue, were cultured with pro-inflammatory factors or bronchoalveolar lavage fluid (BALF) from patients with IPF or idiopathic non-specific interstitial pneumonia (iNSIP) and their fibrotic activity was assessed. Stimulation of SELMs with pro-inflammatory factors induced a significant increase of Tissue Factor (TF) and Tumor necrosis factor-Like cytokine 1 A (TL1A) expression and collagen production in culture supernatants. Stimulation with BALF from IPF patients with mild to moderate, but not severe disease, and from iNSIP patients induced a significant increase of TF expression. BALF from all IPF patients induced a significant increase of TL1A expression and collagen production, while BALF from iNSIP patients induced a significant increase of TL1A, but not of collagen production. Interestingly, TGF-β1 and BALF from all IPF, but not iNSIP patients, induced a significant increase in SELMs migration. In conclusion, BALF from IPF patients induces fibrotic activity in lung myofibroblasts, similar to mediators associated with lung fibrosis, indicating a key role of SELMs in IPF.

Dioscin Exerts Protective Effects Against Crystalline Silica-induced Pulmonary Fibrosis in Mice

Inhalation of crystalline silica particles leads to pulmonary fibrosis, eventually resulting in respiratory failure and death. There are few effective drugs that can delay the progression of this disease; thus, patients with silicosis are usually only offered supportive care. Dioscin, a steroidal saponin, exhibits many biological activities and health benefits including its protective effects against hepatic fibrosis. However, the effect of dioscin on silicosis is unknown.

Methods: We employed experimental mouse mode of silicosis. Different doses of dioscin were gavaged to the animals 1 day after crystalline silica instillation to see the effect of dioscin on crystalline silica induced pulmonary fibrosis. Also, we used RAW264.7 and NIH-3T3 cell lines to explore dioscin effects on macrophages and fibroblasts. Dioscin was also oral treatment but 10 days after crystalline silica instillation to see its effect on established pulmonary fibrosis.

Results: Dioscin treatment reduced pro-inflammation and pro-fibrotic cytokine secretion by modulating innate and adaptive immune responses. It also reduced the recruitment of fibrocytes, protected epithelial cells from crystalline silica injury, inhibited transforming growth factor beta/Smad3 signaling and fibroblast activation. Together, these effects delayed the progression of crystalline silica-induced pulmonary fibrosis. The mechanism by which dioscin treatment alleviated CS-induced inflammation appeared to be via the reduction of macrophage, B lymphocyte, and T lymphocte infiltration into lung. Dioscin inhibits macrophages and fibroblasts from secreting pro-inflammatory cytokines and may also function as a modulator of T helper cells responses, concurrent with attenuated phosphorylation of the apoptosis signal-regulating kinase 1-p38/c-Jun N-terminal kinase pathway. Also, dioscin could block the phosphorylation of Smad3 in fibroblast. Oral treatment of dioscin could also effectively postpone the progression of established silicosis.

Conclusion: Oral treatment dioscin delays crystalline silica-induced pulmonary fibrosis and exerts pulmonary protective effects in mice. Dioscin may be a novel and potent candidate for protection against crystalline silica-induced pulmonary fibrosis.