The role of neutrophils in the pathogenesis of idiopathic pulmonary fibrosis

Cell-Free DNA Maps Tissue Injury and Correlates with Disease Severity in Lung Transplant Candidates

Rationale: Plasma cell-free DNA levels correlate with disease severity in many conditions. Pretransplant cell-free DNA may risk stratify lung transplant candidates for post-transplant complications. Objectives: To evaluate if pretransplant cell-free DNA levels and tissue sources identify patients at high risk of primary graft dysfunction and other pre- and post-transplant outcomes. Methods: This multicenter, prospective cohort study recruited 186 lung transplant candidates. Pretransplant plasma samples were collected to measure cell-free DNA. Bisulfite sequencing was performed to identify the tissue sources of cell-free DNA. Multivariable regression models determined the association between cell-free DNA levels and the primary outcome of primary graft dysfunction and other transplant outcomes, including Lung Allocation Score, chronic lung allograft dysfunction, and death. Measurements and Main Results: Transplant candidates had twofold greater cell-free DNA levels than healthy control patients (median [interquartile range], 23.7 ng/ml [15.1-35.6] vs. 12.9 ng/ml [9.9-18.4]; P < 0.0001), primarily originating from inflammatory innate immune cells. Cell-free DNA levels and tissue sources differed by native lung disease category and correlated with the Lung Allocation Score (P < 0.001). High pretransplant cell-free DNA increased the risk of primary graft dysfunction (odds ratio, 1.60; 95% confidence interval [CI], 1.09-2.46; P = 0.0220), and death (hazard ratio, 1.43; 95% CI, 1.07-1.92; P = 0.0171) but not chronic lung allograft dysfunction (hazard ratio, 1.37; 95% CI, 0.97-1.94; P = 0.0767). Conclusions: Lung transplant candidates demonstrate a heightened degree of tissue injury with elevated cell-free DNA, primarily originating from innate immune cells. Pretransplant plasma cell-free DNA levels predict post-transplant complications.

Association of the lung immune prognostic index with the survival of patients with idiopathic interstitial pneumonias

BACKGROUND AND OBJECTIVE

The lung immune prognostic index (LIPI), a simple index calculated from the blood lactate dehydrogenase level and derived neutrophil-to-lymphocyte ratio, is thought to be associated with host immune status. However, the utility of LIPI in patients with idiopathic interstitial pneumonias (IIPs) is unknown.

METHODS

In this multicentre, retrospective, observational study, an association between LIPI and the survival of patients with IIPs was evaluated.

RESULTS

Exploratory and validation cohorts consisting of 460 and 414 patients with IIPs, respectively, were included (159 and 159 patients had idiopathic pulmonary fibrosis [IPF], and 301 and 255 had non-IPF, respectively). In the exploratory cohort, patients with IPF and a low LIPI had significantly better survival than those with a high LIPI (median of 5.6 years vs. 3.9 years, p = 0.016). The predictive ability of LIPI for the survival of patients with IPF was validated in the validation cohort (median of 8.5 years vs. 4.4 years, p = 0.003). In a multivariate Cox proportional hazard analysis, LIPI was selected as an independent predictive factor for the survival of IPF patients. There was no significant association between LIPI and survival of non-IPF patients in the exploratory and validation cohorts.

CONCLUSION

The LIPI was a predictive factor for the survival of patients with IPF and could aid the management of IPF.

S100 Calcium-Binding Protein A9, a Potential Novel Diagnostic Biomarker for Idiopathic Pulmonary Fibrosis

BACKGROUND

Neutrophilic inflammation is a characteristic feature of idiopathic pulmonary fibrosis (IPF). S100 calcium-binding protein A9 (S100A9) is a neutrophil-derived protein involved in the development of neutrophil-related chronic inflammatory disorders. However, the role of S100A9 in IPF remains unclear.

METHODS

We used enzyme-linked immunosorbent assays to measure S100A9 levels in bronchoalveolar lavage fluid (BALF) and serum obtained from healthy controls (HCs) and patients with IPF, non-specific interstitial pneumonia, hypersensitivity pneumonitis, and sarcoidosis.

RESULTS

Compared with HCs, BALF S100A9 levels were significantly higher in IPF patients (P < 0.001), patients with hypersensitivity pneumonitis (P = 0.043), and patients with nonspecific interstitial pneumonia (P < 0.001). The S100A9 level in BALF of 0.093 ng/mL could distinguish IPF patients from HCs, with a specificity of 78.8% and a sensitivity of 81.6%. Similarly, the S100A9 level in BALF of 0.239 ng/mL had a specificity of 64.7% and a sensitivity of 66.7% for distinguishing IPF patients from patients with other interstitial lung diseases. Additionally, BALF S100A9 levels were significantly correlated with neutrophil counts (r = 0.356, P < 0.001) in BALF. IPF patients with S100A9 levels in BALF > 0.533 ng/mL had lower survival rates, compared with patients who had levels ≤ 0.553 ng/mL (n = 49; hazard ratio [HR], 3.62; P = 0.021). Combination analysis revealed that IPF patients with S100A9 levels in BALF> 0.553 ng/mL or neutrophil percentages > 49.1% (n = 43) had significantly lower survival rates than patients with S100A9 levels in BALF ≤ 0.553 ng/mL and neutrophil percentages ≤ 49.1% (n = 41) (HR, 3.91; P = 0.014). Additionally, patients with serum S100A9 levels > 0.077 ng/mL (n = 29) had significantly lower survival rates than patients with levels ≤ 0.077 ng/mL (n = 53, HR, 2.52; P = 0.013). S100A9 was expressed on neutrophils and macrophages in BALF from IPF patients as well as α-smooth muscle actin positive cells in the lung tissues.

CONCLUSION

S100A9 is involved in the development and progression of IPF. Moreover, S100A9 levels in BALF and serum may be surrogate markers for IPF diagnosis and survival prediction, particularly when analyzed in combination with neutrophil percentages.

Neutrophil levels correlate with quantitative extent and progression of fibrosis in IPF: results of a single-centre cohort study

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with poor prognosis. Clinical studies have demonstrated association between different blood leucocytes and mortality and forced vital capacity (FVC) decline. Here, we question which blood leucocyte levels are specifically associated with progression of fibrosis, measured by accumulation of fibrosis on CT scan using a standardised automated method.

METHODS

Using the Computer-Aided Lung Informatics for Pathology Evaluation and Rating CT algorithm, we determined the correlation between different blood leucocytes (<4 months from CT) and total lung fibrosis (TLF) scores, pulmonary vessel volume (PVV), FVC% and transfer factor of lung for carbon monoxide% at baseline (n=171) and with progression of fibrosis (n=71), the latter using multivariate Cox regression.

RESULTS

Neutrophils (but not monocyte or lymphocytes) correlated with extent of lung fibrosis (TLF/litre) (r=0.208, p=0.007), PVV (r=0.259, p=0.001), FVC% (r=-0.127, p=0.029) at baseline. For the 71 cases with repeat CT; median interval between CTs was 25.9 (16.8-39.9) months. Neutrophil but not monocyte levels are associated with increase in TLF/litre (HR 2.66, 95% CI 1.35 to 5.25, p=0.005).

CONCLUSION

Our study shows that neutrophil rather than monocyte levels correlated with quantifiable increase in fibrosis on imaging of the lungs in IPF, suggesting its relative greater contribution to progression of fibrosis in IPF.

Nintedanib treatment for bleomycin-induced lung injury - First report

Although the antineoplastic agent bleomycin is known for more than 50 years, its exact pharmacological and side-effect mechanisms remain incompletely understood. The major limitation of bleomycin therapy is the risk of pulmonary toxicity which can be diverse, and potentially fatal in 10% of patients. The optimal treatment for bleomycin lung toxicity has not been established and no clinical trials have been performed. Here we present first successful case report of nintedanib therapy in a patient with bleomycin-induced lung injury (BILI). The prevention, early diagnosis, and management of bleomycin pulmonary toxicities are essential, clinical trials are needed in this area.

Higher susceptibility of males to bleomycin-induced pulmonary inflammation is associated with sex-specific transcriptomic differences in myeloid cells

Idiopathic pulmonary fibrosis, a condition with likely genetic and environmental etiology, is relatively more prevalent with poor prognosis in human males. However, the underlying mechanisms for these gender-associated differences in the severity of fibrosis remain unknown. Here, we tested the hypothesis that the transcriptomic repertoire of myeloid cells determines the higher susceptibility of male mice to bleomycin (BLM)-induced lung fibrosis. Adult mice were oropharyngeally challenged with saline or BLM. Lung injury, inflammation, and fibrosis outcomes were assessed, and airspace myeloid-cells were subjected to RNA-sequencing. As compared with the female mice, the male mice manifested significantly increased lung injury, inflammation, proinflammatory cytokines (IL-6, IL-1β, IL-7, and IP-10), and fibrosis in response to BLM challenge. Interestingly, several pro-inflammatory and extracellular matrix-associated genes were significantly up-regulated in male myeloid-cells compared to female myeloid-cells in the saline-control group. Similarly, BLM challenge resulted in greater pro-inflammatory and pro-fibrotic transcriptomic changes in male compared to female myeloid cells. On the other hand, anti-inflammatory and regulatory cytokine, Il10 and Ifng respectively, were uniquely upregulated in BLM-challenged female but not in male myeloid cells when compared to their respective saline-control groups. Further, cross-sex bone marrow transplantation experiments revealed that male hematopoietic progenitor cells (HPCs) increased the granulocytic infiltration in female mice while female HPCs decreased the granulocytic infiltration in male mice post-BLM challenge. These findings suggest that there are inherent transcriptomic differences between the male and female lung myeloid cells and that the pro-inflammatory nature of male myeloid cells is sufficient to increase the susceptibility of female mice to BLM-induced inflammation.

Granulocyte colony-stimulating factor in bronchoalveolar lavage fluid is a potential biomarker for prognostic prediction of idiopathic pulmonary fibrosis

BACKGROUND/AIMS

Neutrophilia is frequently observed in bronchoalveolar lavage fluid (BALF) of idiopathic pulmonary fibrosis (IPF) patients. Granulocyte colony-stimulating factor (G-CSF) is a potent neutrophil-activating glycoprotein. However, the clinical implications of G-CSF remain poorly understood.in patients with IPF. Therefore, we evaluated the relationship between the G-CSF concentration in BALF and the progression of fibrosis, including in terms of the decline in lung function and long-term survival rate.

METHODS

G-CSF concentrations were measured in BALF using enzyme-linked immunosorbent assay (ELISA). The survival rate was estimated using Kaplan-Meier survival analyses.

RESULTS

G-CSF protein levels were significantly higher in IPF (n = 87; 1.88 [0 to 5.68 pg/mL]), nonspecific interstitial pneumonia (n = 22; 0.58 [0 to 11.64 pg/mL]), and hypersensitivity pneumonitis (n = 19; 2.48 [0.46 to 5.71 pg/mL]) patients than in normal controls (n = 33; 0 [0 to 0.68 pg/mL]) (all p &lt; 0.01). A receiver operating characteristic curve showed a difference in G-CSF levels between IPF and NC (area under the curve, 0.769): The G-CSF cut-off of 0.96 pg/mL indicated 84.9% specificity and 63.2% sensitivity for IPF. The survival rate was significantly lower in the group with G-CSF &gt; 2.872 pg/mL than in the group with ≤ 2.872 pg/mL (hazard ratio, 2.69; p = 0.041). The annual decline in diffusing capacity of the lung for carbon monoxide was positively correlated with the G-CSF level (p = 0.018).

CONCLUSION

G-CSF may participate in the development of IPF and be useful for predicting the prognosis of IPF. Therefore, G-CSF should be analyzed in BALF, in addition to differential cell counts.

Lung cancer in never smokers: Tumor immunology and challenges for immunotherapy

Lung cancer is the second most common and the most lethal malignancy worldwide. It is estimated that lung cancer in never smokers (LCINS) accounts for 10-25% of cases, and its incidence is increasing according to recent data, although the reasons remain unclear. If considered alone, LCINS is the 7th most common cause of cancer death. These tumors occur more commonly in younger patients and females. LCINS tend to have a better prognosis, possibly due to a higher chance of bearing an actionable driver mutation, making them amenable to targeted therapy. Notwithstanding, these tumors respond poorly to immune checkpoint inhibitors (ICI). There are several putative explanations for the poor response to immunotherapy: low immunogenicity due to low tumor mutation burden and hence low MANA (mutation-associated neo-antigen) load, constitutive PD-L1 expression in response to driver mutated protein signaling, high expression of immunosuppressive factors by tumors cells (like CD39 and TGF-beta), non-permissive immune TME (tumor microenvironment), abnormal metabolism of amino acids and glucose, and impaired TLS (Tertiary Lymphoid Structures) organization. Finally, there is an increasing concern of offering ICI as first line therapy to these patients owing to several reports of severe toxicity when TKIs (tyrosine kinase inhibitors) are administered sequentially after ICI. Understanding the biology behind the immune response against these tumors is crucial to the development of better therapeutic strategies.

The Dynamic Contribution of Neutrophils in the Chronic Respiratory Diseases

Asthma, chronic obstructive pulmonary disease, and idiopathic pulmonary fibrosis are representative chronic respiratory diseases (CRDs). Although they differ in terms of disease presentation, they are all thought to arise from unresolved inflammation. Neutrophils are not only the first responders to acute inflammation, but they also help resolve the inflammation. Notably, emerging clinical studies show that CRDs are associated with systemic and local elevation of neutrophils. Moreover, murine studies suggest that airway-infiltrating neutrophils not only help initiate airway inflammation but also prolong the inflammation. Given this background, this review describes neutrophil-mediated immune responses in CRDs and summarizes the completed, ongoing, and potential clinical trials that test the therapeutic value of targeting neutrophils in CRDs. The review also clarifies the importance of understanding how neutrophils interact with other immune cells and how these interactions contribute to chronic inflammation in specific CRDs. This information may help identify future therapeutic strategies for CRDs.

Neutrophil lymphocyte ratio as an indicator for disease progression in Idiopathic Pulmonary Fibrosis

RATIONALE

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease. Patients present at different stages and disease course is varied. Blood monocytes have been linked to all-cause mortality, and neutrophils to progression to IPF in patients with the indeterminate for usual interstitial pneumonia CT pattern.

OBJECTIVE

To determine association between blood monocytes, neutrophils and lymphocytes levels (and their derived indexes), with lung function decline and mortality in IPF.

METHODS

We performed a retrospective analysis of an IPF cohort (n=128) who had their first clinical visit at the Oxford Interstitial Lung Disease Service between 2013 and 2017. Association between blood monocytes, neutrophils, lymphocytes and derived indexes (within 4 months of visit) and decline in forced vital capacity (FVC) and all-cause mortality were assessed using Cox proportional hazard regression analysis. Kaplan-Meier analysis was used to assess time-to-event for 10% FVC decline and mortality for patients dichotomised to high and low leucocyte counts.

RESULTS

Median length of follow-up was 31.0 months (IQR 16.2-42.4); 41.4% demonstrated FVC decline >10% per year and 43.8% died. In multivariate models (incorporating age, gender and initial FVC%), raised neutrophils, lymphopaenia and neutrophil:lymphocyte ratio were associated with FVC decline (p≤0.01); while both monocytes and neutrophil levels (and their derived indexes) were associated with all-cause mortality (p≤0.01). Kaplan-Meier analysis also showed association between neutrophils and its derived indexes but not monocyte, with FVC decline.

CONCLUSION

Blood neutrophil and lymphopaenia are more sensitive than monocytes as prognostic indicators of disease progression in those with established IPF.

Implications of the Immune Landscape in COPD and Lung Cancer: Smoking Versus Other Causes

Cigarette smoking is reported in about one third of adults worldwide. A strong relationship between cigarette smoke exposure and chronic obstructive pulmonary disease (COPD) as well as lung cancer has been proven. However, about 15% of lung cancer cases, and between one fourth and one third of COPD cases, occur in never-smokers. The effects of cigarette smoke on the innate as well as the adaptive immune system have been widely investigated. It is assumed that certain immunologic features contribute to lung cancer and COPD development in the absence of smoking as the major risk factor. In this article, we review different immunological aspects of lung cancer and COPD with a special focus on non-smoking related risk factors.

Progress of Statin Therapy in the Treatment of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD) characterized by the proliferation of fibroblasts and aberrant accumulation of extracellular matrix. These changes are accompanied by structural destruction of the lung tissue and the progressive decline of pulmonary function. In the past few decades, researchers have investigated the pathogenesis of IPF and sought a therapeutic approach for its treatment. Some studies have shown that the occurrence of IPF is related to pulmonary inflammatory injury; however, its specific etiology and pathogenesis remain unknown, and no effective treatment, with the exception of lung transplantation, has been identified yet. Several basic science and clinical studies in recent years have shown that statins, the traditional lipid-lowering drugs, exert significant antifibrotic effects, which can delay the progression of IPF and impairment of pulmonary function. This article is aimed at summarizing the current understanding of the pathogenesis of IPF, the progress of research on the use of statins in IPF models and clinical trials, and its main molecular targets.

Normal ex vivo mesenchymal stem cell function combined with abnormal immune profiles sets the stage for informative cell therapy trials in idiopathic pulmonary fibrosis patients

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive pulmonary disease characterized by aberrant tissue remodeling, formation of scar tissue within the lungs and continuous loss of lung function. The areas of fibrosis seen in lungs of IPF patients share many features with normal aging lung including cellular senescence. The contribution of the immune system to the etiology of IPF remains poorly understood. Evidence obtained from animal models and human studies suggests that innate and adaptive immune processes can orchestrate existing fibrotic responses. Currently, there is only modest effective pharmacotherapy for IPF. Mesenchymal stem cells (MSCs)-based therapies have emerged as a potential option treatment of IPF. This study characterizes the functionality of autologous MSCs for use as an IPF therapy and presents an attempt to determine whether the disease occurring in the lungs is associated with an alterated immune system.

METHODS

Comprehensive characterization of autologous adipose-derived MSCs (aMSCs) from 5 IPF patient and 5 age- and gender-matched healthy controls (HC) was done using flow cytometry, PCR (ddPCR), multiplex Luminex xMAP technology, confocal microscopy self-renewal capacity and osteogenic differentiation. Additionally, multi-parameter quantitative flow cytometry of unmanipulated whole blood of 15 IPF patients and 87 (30 age- and gender-matched) HC was used to analyze 110 peripheral phenotypes to determine disease-associated changes in the immune system.

RESULTS

There are no differences between autologous aMSCs from IPF patients and HC in their stem cell properties, self-renewal capacity, osteogenic differentiation, secretome content, cell cycle inhibitor marker levels and mitochondrial health. IPF patients had altered peripheral blood immunophenotype including reduced B cells subsets, increased T cell subsets and increased granulocytes demonstrating disease-associated alterations in the immune system.

CONCLUSIONS

Our results indicate that there are no differences in aMSC properties from IPF patients and HC, suggesting that autologous aMSCs may be an acceptable option for IPF therapy. The altered immune system of IPF patients may be a valuable biomarker for disease burden and monitoring therapeutic response.

Use of peripheral neutrophil to lymphocyte ratio and peripheral monocyte levels to predict survival in fibrotic hypersensitivity pneumonitis (fHP): a multicentre retrospective cohort study

The factors determining disease course and survival in fibrotic hypersensitivity pneumonitis (fHP) have not been fully elucidated.The aim of this study was to describe the characteristics of patients with fHP in a real-world cohort and investigate factors associated with worse outcomes. We aimed to explore the use of neutrophil to lymphocyte ratio (NLR) and peripheral blood monocyte levels in predicting mortality.

METHODS

A retrospective, multicentre, observational UK cohort study.

RESULTS

Patients with fHP were significantly younger than those with idiopathic pulmonary fibrosis (IPF) (median age fHP 73 vs IPF 75 years) and were much more likely to be woman (fHP 61% vs IPF 26%). In almost half of all fHP cases (49%, n=104/211), no causative antigen was identified from either the history or specific antigen testing. Overall, fHP was associated with a better survival than IPF, although median survival of both groups was poor (fHP 62 months vs IPF 52 months).IPF survival in patients with a high NLR was significantly lower than those with a low NLR (44 vs 83 months). A monocyte count ≥0.95 K/uL also predicted significantly poorer outcomes for patients with IPF compared with <0.95 K/uL (33 vs 57 months). In contrast, NLR and monocyte count did not predict survival in the fHP cohort.

CONCLUSIONS

Although fHP has a statistically lower mortality than IPF, absolute survival time of both conditions is poor. High baseline NLR and absolute monocyte counts predict worse survival in IPF but not in fHP, highlighting the potential for divergence in their pathogenic mechanisms.

Evolving Perspectives on Innate Immune Mechanisms of IPF

While epithelial-fibroblast interactions are viewed as the primary drivers of Idiopathic Pulmonary Fibrosis (IPF), evidence gleaned from animal modeling and human studies implicates innate immunity as well. To provide perspective on this topic, this review synthesizes the available data regarding the complex role of innate immunity in IPF. The role of substances present in the fibrotic microenvironment including pathogen associated molecular patterns (PAMPs) derived from invading or commensal microbes, and danger associated molecular patterns (DAMPs) derived from injured cells and tissues will be discussed along with the proposed contribution of innate immune populations such as macrophages, neutrophils, fibrocytes, myeloid suppressor cells, and innate lymphoid cells. Each component will be considered in the context of its relationship to environmental and genetic factors, disease outcomes, and potential therapies. We conclude with discussion of unanswered questions and opportunities for future study in this area.

Prognostic significance of peripheral blood monocyte and neutrophil counts in rheumatoid arthritis-associated interstitial lung disease

OBJECTIVES

Interstitial lung disease (ILD) is a common pulmonary manifestation of rheumatoid arthritis (RA) associated with clinical heterogeneity and high mortality. This study aimed to determine whether non-invasive biomarkers, especially monocyte count in peripheral blood, would be useful for predicting outcomes in patients with RA-associated ILD (RA-ILD).

METHODS

We retrospectively reviewed the medical records of 72 patients with RA-ILD. We assessed clinical characteristics, laboratory findings at the time of diagnosis. We used Cox proportional hazard analyses to determine significant variables associated with outcomes. Cumulative survival rates were calculated using the Kaplan-Meier method.

RESULTS

The median age was 68.6 years (58% male). The 5-year survival rate was 78.4%. Cox proportional hazard analyses adjusted by age and sex showed that increased monocyte count and neutrophil count were significantly associated with poor prognosis in patients with RA-ILD. According to optimal cutoff levels, patients with high monocyte counts (≥458/μl) had significantly lower survival rates than those with low monocyte counts (<458/μl). Similarly, patients with high neutrophil counts (≥9394/μl) had significantly lower survival rates than those with low neutrophil counts (<9394/μl). Combinatorial assessments with peripheral monocyte and neutrophil counts revealed that the patients with both high monocyte and neutrophil counts had the lowest survival.

CONCLUSIONS

Increased monocyte and neutrophil counts might be potential cellular biomarkers to predict poor outcomes in patients with RA-ILD.

A proposed role of neutrophil extracellular traps and their interplay with fibroblasts in ANCA-associated vasculitis lung fibrosis

ANCA-associated vasculitides (AAV) comprise three diseases: granulomatosis with polyangiitis, microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis. They are characterised by small vessel inflammation and have a broad range of clinical manifestations and multiorgan involvement which endanger the patient's life. An increasingly recognised complication of AAV, especially in MPA is lung fibrosis, for which no clearcut therapy in this context is available. The release of neutrophil extracellular traps (NETs) in these diseases has been related to the development of fibrosis, but the precise mechanisms are not fully unravelled. This review provides an overview of some of the important proteins known to compose NETs, and proposes some mechanisms by which these remarkable components may exert an impact on the different fibroblastic phenotypes leading to lung fibrosis.

The Roles of Immune Cells in the Pathogenesis of Fibrosis

Tissue injury and inflammatory response trigger the development of fibrosis in various diseases. It has been recognized that both innate and adaptive immune cells are important players with multifaceted functions in fibrogenesis. The activated immune cells produce various cytokines, modulate the differentiation and functions of myofibroblasts via diverse molecular mechanisms, and regulate fibrotic development. The immune cells exhibit differential functions during different stages of fibrotic diseases. In this review, we summarized recent advances in understanding the roles of immune cells in regulating fibrotic development and immune-based therapies in different disorders and discuss the underlying molecular mechanisms with a focus on mTOR and JAK-STAT signaling pathways.

Nintedanib Reduces Neutrophil Chemotaxis via Activating GRK2 in Bleomycin-Induced Pulmonary Fibrosis

Neutrophils are involved in the alveolitis of idiopathic pulmonary fibrosis (IPF). However, their pathogenic mechanisms are still poorly understood. Nintedanib has antifibrotic and anti-inflammatory activity in IPF. This study aimed to investigate the regulatory mechanism of nintedanib on neutrophil chemotaxis in bleomycin (BLM)-induced pulmonary fibrosis. Nintedanib was administered via oral gavage to male C57BL/6 mice 24 h after a bleomycin intratracheal injection (1.5 U/kg). Lung histopathological findings, the expression of cytokines, and the regulatory signaling pathways of neutrophil chemotaxis were analyzed. The effect of nintedanib was also investigated in a mouse model with adoptive neutrophil transfer in vivo. Nintedanib significantly decreased the histopathological changes and neutrophil recruitment in BLM-induced pulmonary fibrosis. Nintedanib mediated a downregulation of chemokine (C-X-C motif) receptor 2 (CXCR2) and very late antigen 4 (VLA-4) expression, as well as an upregulation of G protein-coupled receptor kinase 2 (GRK2) activity in peripheral blood neutrophils in BLM-induced pulmonary fibrosis. Nintedanib also decreased the activation of endothelial cells by the decreased expression of vascular cell adhesion molecule 1 (VCAM-1). The effect of nintedanib on regulating neutrophil chemotaxis was also confirmed by a mouse model with adoptive neutrophil transfer in vivo. In conclusion, nintedanib reduces neutrophil chemotaxis and endothelial cell activation to regulate the severity of BLM-induced pulmonary fibrosis. These effects are associated with an enhancement of GRK2 activity and a reduction in CXCR2 and VLA-4 expression on neutrophils and a decrease in VCAM-1 expression on endothelial cells.

Comprehensive analysis of lncRNA-associated competing endogenous RNA network and immune infiltration in idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is a life-threatening lung disorder with an unknown aetiology. The roles of long non-coding RNAs (lncRNAs) and its related competing endogenous RNAs (ceRNA) network in IPF remains poorly understood. In this study, we aimed to build a lncRNA-miRNA-mRNA network and explore the pathogenesis of IPF.

Methods

We screened differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) between IPF and control lung tissues from two datasets. The ceRNA network was built according to the interactions between DElncRNA, miRNA, and DEmRNA. Functional enrichment analysis of DemRNAs was performed using Metascape. CIBERSORT (Cell type Identification by Estimating Relative Subsets Of known RNA Transcripts) was applied to estimate the fraction of 22 immune cells in IPF and controls lung tissue samples. Then we investigated the correlation between immune cells and clinical traits.

Results

We constructed a lncRNA-miRNA-mRNA network, which was composed of two DElncRNAs, 18 miRNAs, 66 DemRNAs. Functional enrichment analysis showed that the DEmRNAs mainly participated in MicroRNAs in cancer. By applying CIBERSORT, we found that IPF tissue samples had a higher proportion of plasma cells, resting mast cells and a lower proportion of resting NK cells, monocytes, neutrophils compared with control tissue samples. Also, our results indicated that immune cells were associated with the severity of IPF.

Conclusions

In summary, this is the first study to build lncRNA-miRNA-mRNA ceRNA network of IPF, which may improve our understanding of IPF pathogenesis. Our study indicates that immune cells in lung tissues may predict disease severity and participate in the development of IPF. Future prospective studies are required to confirm the findings of the current study.

Proportions of resting memory T cells and monocytes in blood have prognostic significance in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterized by progressive decline of lung function. Here, we tested the importance of differential proportions of blood immune cells to IPF clinical outcomes. We used Cibersort to deconvolute immune cell components based on PBMCs or whole blood IPF genomics datasets. We found that a higher proportion of resting memory (RM) T cells was associated with a better survival and a higher DLco (diffusing capacity for carbon monoxide) in IPF patients. The association was also found in opposite direction for monocytes. Additionally, in IPF patients as compared to healthy controls, proportions of monocytes were observed to be higher, yet RM T cells were observed to be lower. Taken together, our result suggests a beneficial effect of RM T cells and a detrimental effect of monocytes for IPF. Future genomics studies of IPF should be more focused on these two types of cells.

Epithelial Expression of an Interstitial Lung Disease-Associated Mutation in Surfactant Protein-C Modulates Recruitment and Activation of Key Myeloid Cell Populations in Mice

Patients with idiopathic pulmonary fibrosis (IPF) often experience precipitous deteriorations, termed "acute exacerbations" (AE), marked by diffuse alveolitis and altered gas exchange, resulting in a significant loss of lung function or mortality. The missense isoleucine to threonine substitution at position 73 (I73T) in the alveolar type 2 cell-restricted surfactant protein-C (SP-C) gene (SFTPC) has been linked to clinical IPF. To better understand the sequence of events that impact AE-IPF, we leveraged a murine model of inducible SP-C^I73T (SP-C^I73T/I73TFlp^+/- ) expression. Following administration of tamoxifen to 8-12-wk-old mice, an upregulation of Sftpc^I73T initiated a diffuse lung injury marked by increases in bronchoalveolar lavage fluid (BALF) protein and histochemical evidence of CD45⁺ and CD11b⁺ cell infiltrates. Flow cytometry of collagenase-digested lung cells revealed a transient, early reduction in SiglecF^hiCD11b^lowCD64^hiCD11c^hi macrophages, countered by the sequential accumulation of SiglecF^loCD11b⁺CD64^-CD11c^-CCR2⁺Ly6C⁺ immature macrophages (3 d), Ly6G⁺ neutrophils (7 d), and SiglecF^hiCD11b^hiCD11c^lo eosinophils (2 wk). By mRNA analysis, BALF cells demonstrated a time-dependent phenotypic shift from a proinflammatory (3 d) to an anti-inflammatory/profibrotic activation state, along with serial elaboration of monocyte and eosinophil recruitment factors. The i.v. administration of clodronate effectively reduced total BALF cell numbers, CCR2⁺ immature macrophages, and eosinophil influx while improving survival. In contrast, resident macrophage depletion from the intratracheal delivery of clodronate liposomes enhanced Sftpc^I73T -induced mortality. These results using Sftpc^I73T mice provide a detailed ontogeny for AE-IPF driven by alveolar epithelial dysfunction that induces a polycellular inflammation initiated by the early influx of proinflammatory CCR2⁺Ly6C^hi immature macrophages.

Secretory immunoglobulin A induces human lung fibroblasts to produce inflammatory cytokines and undergo activation

Immunoglobulin (Ig)A is the most abundant immunoglobulin in humans, and in the airway mucosa secretory IgA (sIgA) plays a pivotal role in first-line defense against invading pathogens and antigens. IgA has been reported to also have pathogenic effects, including possible worsening of the prognosis of idiopathic pulmonary fibrosis (IPF). However, the precise effects of IgA on lung fibroblasts remain unclear, and we aimed to elucidate how IgA activates human lung fibroblasts. We found that sIgA, but not monomeric IgA (mIgA), induced interleukin (IL)-6, IL-8, monocyte chemoattractant protein (MCP)-1 and granulocyte-macrophage colony-stimulating factor (GM-CSF) production by normal human lung fibroblasts (NHLFs) at both the protein and mRNA levels. sIgA also promoted proliferation of NHLFs and collagen gel contraction comparable to with transforming growth factor (TGF)-β, which is involved in fibrogenesis in IPF. Also, Western blot analysis and real-time quantitative polymerase chain reaction (PCR) revealed that sIgA enhanced production of α-smooth muscle actin (α-SMA) and collagen type I (Col I) by NHLFs. Flow cytometry showed that NHLFs bound sIgA, and among the known IgA receptors, NHLFs significantly expressed CD71 (transferrin receptor). Transfection of siRNA targeting CD71 partially but significantly suppressed cytokine production by NHLFs co-cultured with sIgA. Our findings suggest that sIgA may promote human lung inflammation and fibrosis by enhancing production of inflammatory or fibrogenic cytokines as well as extracellular matrix, inducing fibroblast differentiation into myofibroblasts and promoting human lung fibroblast proliferation. sIgA's enhancement of cytokine production may be due partially to its binding to CD71 or the secretory component.

Ibrutinib Exacerbates Bleomycin-Induced Pulmonary Fibrosis via Promoting Inflammation

Idiopathic pulmonary fibrosis (IPF) is a progressive and irreversible lung disease with high mortality rate. The etiology is unknown and treatment choices are limited. Thus, there is great interest to investigate novel agents for IPF therapy. Ibrutinib, BTK, and ITK irreversible inhibitor is a FDA-approved small molecule for the clinical therapy of B cell lymphoma. Its role in pulmonary fibrosis remains unknown. In this study, we investigated the anti-fibrotic activity of ibrutinib. Strikingly, ibrutinib did not inhibit but exacerbated bleomycin-induced pulmonary fibrosis by increased epithelial cell apoptosis, and inflammation in the lung. The upregulated TGF-β and EMT transformation also contributes to enhanced myofibroblast differentiation and ECM deposition. Our findings reveal the detrimental effects of ibrutinib against bleomycin-mediated fibrosis and added to the understanding of IPF pathogenesis.

Oxidation-resistant and thermostable forms of alpha-1 antitrypsin from Escherichia coli inclusion bodies

Native α1‐antitrypsin (AAT) is a 52‐kDa glycoprotein that acts as an antiprotease and is the physiological inhibitor of neutrophil serine proteases. The main function of AAT is to protect the lung from proteolytic damage induced by inflammation. AAT deficiency (AATD) is a codominant autosomal disorder caused by pathogenic mutations in SERPINA1 gene, leading to reduced levels of serum AAT. The deficiency is known to increase the risk of pulmonary emphysema and chronic obstructive pulmonary disease as a consequence of proteolytic imbalance induced by inflammation, associated in many instances with cigarette smoking and other environmental hazards. Currently, the available therapy for lung disease associated with AATD is serum purified human AAT injected into patients on a weekly basis. It would be advantageous to replace serum‐derived AAT with a recombinant version which is stable and resistant to oxidation. We have expressed AAT in Escherichia coli as inclusion bodies and developed a highly efficient refolding and purification process. We engineered a series of mutant forms of AAT to achieve enhance thermostability and oxidation resistance. Moreover, we synthesized an active form of AAT via cysteine‐pegylation to achieve a markedly extended half‐life in vivo. The resulting molecule, which retains comparable activity to the wild‐type form, is expected to be an improved therapeutic agent for treating hereditary emphysema. In addition, the molecule may also be used to treat other types of emphysema caused by smoking, cystic fibrosis, pulmonary hypertension, pulmonary fibrosis, and chronic obstructive pulmonary disease.

An Adaptogen: Withaferin A Ameliorates in Vitro and in Vivo Pulmonary Fibrosis by Modulating the Interplay of Fibrotic, Matricelluar Proteins, and Cytokines

Pulmonary fibrosis (PF) is chronic lung disease with only two FDA approved clinically available drugs, with limited safety profile. Inadequate therapy motivated us to explore the effect of vimentin inhibitor Withaferin A, as an anti-fibrotic agent against TGF-β1-induced in vitro fibrotic events and Bleomycin induced in vivo fibrosis with an emphasis on epithelial to mesenchymal transition (EMT), extracellular matrix deposition (ECM), inflammation, and angiogenesis. In vitro EMT and fibrotic events were induced by TGF-β1 in alveolar epithelial cells and human fetal lung fibroblasts followed by treatment with Withaferin A (0.25, 0.5, and 1 μM concentrations) to explore its anti-fibrotic effects. In vivo potential of Withaferin A (2 and 4 mg/kg) was assessed in murine model of Bleomycin induced PF. All the parameters and molecular studies related to PF were performed at the end of treatment period. Withaferin A treatment reduced the progression of PF by modulating the EMT related cell markers both in vivo and in vitro. Withaferin A ameliorated the expression of inflammatory cytokines including NF-κB p65, IL-1β and TNF-α, as well as attenuated the expression of pro-fibrotic proteins including CTGF, collagen 1A2, collagen 3A1, and fibronectin. Expression of angiogenic factors like VEGF, FAK, p38 MAPK, and PLC-γ1 were also inhibited by Withaferin A. Phosphorylation of Smad 2/3 induced by TGF-β1 and Bleomycin were significantly inhibited. Withaferin A suppressed expression of pro-inflammatory, pro-fibrotic, and pro-angiogenic mediators and also reduced the ECM deposition. In a nutshell, Withaferin A could probably prove as an efficient and potential therapeutic against PF.

The Role of Immune and Inflammatory Cells in Idiopathic Pulmonary Fibrosis

The contribution of the immune system to idiopathic pulmonary fibrosis (IPF) remains poorly understood. While most sources agree that IPF does not result from a primary immunopathogenic mechanism, evidence gleaned from animal modeling and human studies suggests that innate and adaptive immune processes can orchestrate existing fibrotic responses. This review will synthesize the available data regarding the complex role of professional immune cells in IPF. The role of innate immune populations such as monocytes, macrophages, myeloid suppressor cells, and innate lymphoid cells will be discussed, as will the activation of these cells via pathogen-associated molecular patterns derived from invading or commensural microbes, and danger-associated molecular patterns derived from injured cells and tissues. The contribution of adaptive immune responses driven by T-helper cells and B cells will be reviewed as well. Each form of immune activation will be discussed in the context of its relationship to environmental and genetic factors, disease outcomes, and potential therapies. We conclude with discussion of unanswered questions and opportunities for future study in this area.

The diversity of myeloid immune cells shaping wound repair and fibrosis in the lung

In healthy circumstances the immune system coordinates tissue repair responses in a tight balance that entails efficient inflammation for removal of potential threats, proper wound closure, and regeneration to regain tissue function. Pathological conditions, continuous exposure to noxious agents, and even ageing can dysregulate immune responses after injury. This dysregulation can lead to a chronic repair mechanism known as fibrosis. Alterations in wound healing can occur in many organs, but our focus lies with the lung as it requires highly regulated immune and repair responses with its continuous exposure to airborne threats. Dysregulated repair responses can lead to pulmonary fibrosis but the exact reason for its development is often not known. Here, we review the diversity of innate immune cells of myeloid origin that are involved in tissue repair and we illustrate how these cell types can contribute to the development of pulmonary fibrosis. Moreover, we briefly discuss the effect of age on innate immune responses and therefore on wound healing and we conclude with the implications of current knowledge on the avenues for future research.

Conjunctival Neutrophils Predict Progressive Scarring in Ocular Mucous Membrane Pemphigoid

Purpose

Ocular mucous membrane pemphigoid (OcMMP) is a rare autoimmune disorder resulting in progressive conjunctival fibrosis and ocular surface failure leading to sight loss in up to 50%. This study was designed to optimize an ocular surface sampling technique for identification of novel biomarkers associated with disease activity and/or progressive fibrosis.

Methods

Fifty-seven patients with OcMMP underwent detailed examination of conjunctival inflammation and fibrosis using fornix depth measurement. Ocular surface impression cytology (OSIC) to sample superior bulbar conjunctiva combined with flow cytometry (OSIC-flow) profiled infiltrating leukocytes. Profiles were compared with healthy controls (HC) and disease controls (primary Sjögren's syndrome, pSS). Thirty-five OcMMP patients were followed every 3 months for 12 months.

Results

Overall neutrophils were elevated in OcMMP eyes when compared to pSS or HC (109 [18%] neutrophils/impression [NPI]; 2 [0.2%]; 6 [0.8%], respectively [P < 0.0001]) and in OcMMP patients with no visible inflammation when compared with HC (44.3 [7.9%]; 5.8 [0.8%]; P < 0.05). At 12 months follow-up, 53% of OcMMP eyes progressed, and this was associated with baseline conjunctival neutrophilia (P = 0.004). As a potential biomarker, a value of 44 NPI had sensitivity, specificity, and positive predictive values of 75%, 70%, and 73%, respectively. Notably, eyes with no visible inflammation and raised conjunctival neutrophils were more likely to progress and have a greater degree of conjunctival shrinkage compared to those without raised neutrophils.

Conclusions

These data suggest that OSIC-flow cytometric analyses may facilitate repeated patient sampling. Neutrophils may act as a biomarker for monitoring disease activity, progressive fibrosis, and response to therapy in OcMMP even when the eye appears clinically uninflamed.

Role of Nonneuronal TRPV4 Signaling in Inflammatory Processes

Transient receptor potential (TRP) ion channels are important signaling components in nociceptive and inflammatory pathways. This is attributed to their ability to function as polymodal sensors of environmental stimuli (chemical and mechanical) and as effector molecules in receptor signaling pathways. TRP vanilloid 4 (TRPV4) is a nonselective cation channel that is activated by multiple endogenous stimuli including shear stress, membrane stretch, and arachidonic acid metabolites. TRPV4 contributes to many important physiological processes and dysregulation of its activity is associated with chronic conditions of metabolism, inflammation, peripheral neuropathies, musculoskeletal development, and cardiovascular regulation. Mechanosensory and receptor- or lipid-mediated signaling functions of TRPV4 have historically been attributed to central and peripheral neurons. However, with the development of potent and selective pharmacological tools, transgenic mice and improved molecular and imaging techniques, many new roles for TRPV4 have been revealed in nonneuronal cells. In this chapter, we discuss these recent findings and highlight the need for greater characterization of TRPV4-mediated signaling in nonneuronal cell types that are either directly associated with neurons or indirectly control their excitability through release of sensitizing cellular factors. We address the integral role of these cells in sensory and inflammatory processes as well as their importance when considering undesirable on-target effects that may be caused by systemic delivery of TRPV4-selective pharmaceutical agents for treatment of chronic diseases. In future, this will drive a need for targeted drug delivery strategies to regulate such a diverse and promiscuous protein.

The Role and Immunobiology of Eosinophils in the Respiratory System: a Comprehensive Review

The eosinophil is a fully delineated granulocyte that disseminates throughout the bloodstream to end-organs after complete maturation in the bone marrow. While the presence of eosinophils is not uncommon even in healthy individuals, these granulocytes play a central role in inflammation and allergic processes. Normally appearing in smaller numbers, higher levels of eosinophils in the peripheral blood or certain tissues typically signal a pathologic process. Eosinophils confer a beneficial effect on the host by enhancing immunity against molds and viruses. However, tissue-specific elevation of eosinophils, particularly in the respiratory system, can cause a variety of short-term symptoms and may lead to long-term sequelae. Eosinophils often play a role in more commonly encountered disease processes, such as asthma and allergic responses in the upper respiratory tract. They are also integral in the pathology of less common diseases including eosinophilic pneumonia, allergic bronchopulmonary aspergillosis, hypersensitivity pneumonitis, and drug reaction with eosinophilia and systemic symptoms. They can be seen in neoplastic disorders or occupational exposures as well. The involvement of eosinophils in pulmonary disease processes can affect the method of diagnosis and the selection of treatment modalities. By analyzing the complex interaction between the eosinophil and its environment, which includes signaling molecules and tissues, different therapies have been discovered and created in order to target disease processes at a cellular level. Innovative treatments such as mepolizumab and benralizumab will be discussed. The purpose of this article is to further explore the topic of eosinophilic presence, activity, and pathology in the respiratory tract, as well as discuss current and future treatment options through a detailed literature review.

Amnion Epithelial Cells Promote Lung Repair via Lipoxin A4

Human amnion epithelial cells (hAECs) have been shown to possess potent immunomodulatory properties across a number of disease models. Recently, we reported that hAECs influence macrophage polarization and activity, and that this step was dependent on regulatory T cells. In this study, we aimed to assess the effects of hAEC-derived proresolution lipoxin-A₄ (LXA4) on T-cell, macrophage, and neutrophil phenotype and function during the acute phase of bleomycin-induced lung injury. Using C57Bl6 mice, we administered 4 million hAECs intraperitoneally 24 hours after bleomycin challenge. Outcomes were measured at days 3, 5, and 7. hAEC administration resulted in significant changes to T-cell, macrophage, dendritic cell, and monocyte/macrophage infiltration and phenotypes. Endogenous levels of lipoxygenases, LXA4, and the lipoxin receptor FPR2 were elevated in hAEC-treated animals. Furthermore, we showed that the effects of hAECs on macrophage phagocytic activity and T-cell suppression are LXA4 dependent, whereas the inhibition of neutrophil-derived myleoperoxidase by hAECs is independent of LXA4. This study provides the first evidence that lipid-based mediators contribute to the immunomodulatory effects of hAECs and further supports the growing body of evidence that LXA4 is proresolutionary in lung injury. This discovery of LXA4-dependent communication between hAECs, macrophages, T cells, and neutrophils is important to the understanding of hAEC biodynamics and would be expected to inform future clinical applications. Stem Cells Translational Medicine 2017;6:1085-1095.

CYFRA 21.1 in bronchoalveolar lavage of idiopathic pulmonary fibrosis patients

AIM

Idiopathic pulmonary fibrosis (IPF) is one of the most aggressive forms of interstitial lung diseases, however, clinically relevant biomarkers of diagnosis or prognosis are lacking. In this study, we investigated the levels of a fragment of Cytokeratin 19 (CYFRA 21.1) in bronchoalveolar lavage (BAL) of IPF patients at time of diagnosis. We further evaluated associations between CYFRA 21.1, pulmonary function evolution, mortality, and BAL cell count.

MATERIALS AND METHODS

Using the Lumipulse® G1200, CYFRA 21.1 was measured in BAL samples of 81 IPF patients and 9 controls. Based upon the median detected level (1.2 ng/mL) of CYFRA 21.1 in IPF patients, they were subdivided into an IPF CYFRA 21.1 low group (≤ 1.2 ng/mL) and IPF CYFRA 21.1 high group (> 1.2 ng/mL).

RESULTS

The CYFRA 21.1 levels were significantly higher in BAL of IPF patients compared to controls (P = .0015).Worse survival was observed, but no changes in pulmonary function, for IPF patients with high CYFRA 21.1 levels versus patients with low CYFRA 21.1 levels [P = .030, HR: 0.41, (0.18-0.92)[. The CYFRA 21.1 level correlated with both neutrophils (%: R = 0.60, P < .0001; #: R = 0.47, P < .0001) and eosinophils (%: R = 0.38, P = .0005; #: R = 0.30, P < .0072).

CONCLUSIONS

CYFRA 21.1 is increased in BAL of IPF patients. IPF patients with a high CYFRA 21.1 concentration have a worse survival. CYFRA 21.1 levels correlate with eosinophils and neutrophils. Further studies are warranted in using CYFRA 21.1 as a biomarker for IPF prognosis.

Secretory leukocyte protease inhibitor gene deletion alters bleomycin-induced lung injury, but not development of pulmonary fibrosis

Idiopathic pulmonary fibrosis is a progressive, fatal disease with limited treatment options. Protease-mediated transforming growth factor-β (TGF-β) activation has been proposed as a pathogenic mechanism of lung fibrosis. Protease activity in the lung is tightly regulated by protease inhibitors, particularly secretory leukocyte protease inhibitor (SLPI). The bleomycin model of lung fibrosis was used to determine the effect of increased protease activity in the lungs of Slpi(-/-) mice following injury. Slpi(-/-), and wild-type, mice received oropharyngeal administration of bleomycin (30 IU) and the development of pulmonary fibrosis was assessed. Pro and active forms of matrix metalloproteinase (MMP)-2 and MMP-9 were measured. Lung fibrosis was determined by collagen subtype-specific gene expression, hydroxyproline concentration, and histological assessment. Alveolar TGF-β activation was measured using bronchoalveolar lavage cell pSmad2 levels and global TGF-β activity was assessed by pSmad2 immunohistochemistry. The active-MMP-9 to pro-MMP-9 ratio was significantly increased in Slpi(-/-) animals compared with wild-type animals, demonstrating enhanced metalloproteinase activity. Wild-type animals showed an increase in TGF-β activation following bleomycin, with a progressive and sustained increase in collagen type I, alpha 1 (Col1α1), III, alpha 1(Col3α1), IV, alpha 1(Col4α1) mRNA expression, and a significant increase in total lung collagen 28 days post bleomycin. In contrast Slpi(-/-) mice showed no significant increase of alveolar TGF-β activity following bleomycin, above their already elevated levels, although global TGF-β activity did increase. Slpi(-/-) mice had impaired collagen gene expression but animals demonstrated minimal reduction in lung fibrosis compared with wild-type animals. These data suggest that enhanced proteolysis does not further enhance TGF-β activation, and inhibits sustained Col1α1, Col3α1, and Col4α1 gene expression following lung injury. However, these changes do not prevent the development of lung fibrosis. Overall, these data suggest that the absence of Slpi does not markedly modify the development of lung fibrosis following bleomycin-induced lung injury.

Targeting of Discoidin Domain Receptor 2 (DDR2) Prevents Myofibroblast Activation and Neovessel Formation During Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lethal human disease with short survival time and few treatment options. Herein, we demonstrated that discoidin domain receptor 2 (DDR2), a receptor tyrosine kinase that predominantly transduces signals from fibrillar collagens, plays a critical role in the induction of fibrosis and angiogenesis in the lung. In vitro cell studies showed that DDR2 can synergize the actions of both transforming growth factor (TGF)-β and fibrillar collagen to stimulate lung fibroblasts to undergo myofibroblastic changes and vascular endothelial growth factor (VEGF) expression. In addition, we confirmed that late treatment of the injured mice with specific siRNA against DDR2 or its kinase inhibitor exhibited therapeutic efficacy against lung fibrosis. Thus, this study not only elucidated novel mechanisms by which DDR2 controls the development of pulmonary fibrosis, but also provided candidate target for the intervention of this stubborn disease.

Hyaluronidase-loaded PLGA microparticles as a new strategy for the treatment of pulmonary fibrosis

The aim of this work was to develop an innovative tool for the treatment of pulmonary fibrosis based on our previous findings, which demonstrated that intranasally administered soluble bovine hyaluronidase (HYAL) increases the numbers of mesenchymal (MSC)-like cells in the bronchoalveolar fluid (BALF) and thus reduces the bleomycin-induced fibrosis. To this end, we developed poly(D,L-lactide-co-glycolide) (PLGA) microparticles (MPs) loaded with HYAL (HYAL-MP) to preserve the enzyme's biological activity and to facilitate its delivery to the lung. Nonloaded MPs (Control-MPs) and HYAL-MPs were prepared using the emulsion and solvent evaporation methods and thoroughly characterized. The HYAL-MPs and Control-MPs exhibited an average diameter of 4.3±2.1 and 4.4±1.5 μm, respectively. The encapsulation efficiency of the HYAL-MPs was 68%, and encapsulation led to a reduced release rate. Additionally, the HYAL-MPs were efficiently phagocytosed by J-774.1 cells. Compared with the soluble HYAL, the HYAL-MPs increased the proportion of MSC-like cells in the BALF of C57BL6 mice 96 h after treatment. The efficacy of the HYAL-MPs was also tested in C57BL6 mice that were previously exposed to 4 U/kg of bleomycin to induce lung fibrosis. The results demonstrated that the HYAL-MPs reduced neutrophil recruitment after bleomycin treatment more effectively than did the soluble HYAL, whereas the Control-MPs did not exhibit any effect. The HYAL-MPs also reduced the bleomycin-induced fibrosis more efficiently, and 134% of the collagen deposition in the lung compared with the soluble HYAL and the Control-MPs. In summary, our data indicate that HYAL-MPs are an effective delivery system that could feasibly be used in the treatment of pulmonary fibrosis.

CD8+ T Cell Response to Gammaherpesvirus Infection Mediates Inflammation and Fibrosis in Interferon Gamma Receptor-Deficient Mice

Idiopathic pulmonary fibrosis (IPF), one of the most severe interstitial lung diseases, is a progressive fibrotic disorder of unknown etiology. However, there is growing appreciation for the role of viral infection in disease induction and/or progression. A small animal model of multi-organ fibrosis, which involves murine gammaherpesvirus (MHV68) infection of interferon gamma receptor deficient (IFNγR-/-) mice, has been utilized to model the association of gammaherpesvirus infections and lung fibrosis. Notably, several MHV68 mutants which fail to induce fibrosis have been identified. Our current study aimed to better define the role of the unique MHV68 gene, M1, in development of pulmonary fibrosis. We have previously shown that the M1 gene encodes a secreted protein which possesses superantigen-like function to drive the expansion and activation of Vβ4+ CD8+ T cells. Here we show that M1-dependent fibrosis is correlated with heightened levels of inflammation in the lung. We observe an M1-dependent cellular infiltrate of innate immune cells with most striking differences at 28 days-post infection. Furthermore, in the absence of M1 protein expression we observed reduced CD8+ T cells and MHV68 epitope specific CD8+ T cells to the lungs-despite equivalent levels of viral replication between M1 null and wild type MHV68. Notably, backcrossing the IFNγR-/- onto the Balb/c background, which has previously been shown to exhibit weak MHV68-driven Vβ4+ CD8+ T cell expansion, eliminated MHV68-induced fibrosis-further implicating the activated Vβ4+ CD8+ T cell population in the induction of fibrosis. We further addressed the role that CD8+ T cells play in the induction of fibrosis by depleting CD8+ T cells, which protected the mice from fibrotic disease. Taken together these findings are consistent with the hypothesized role of Vβ4+ CD8+ T cells as mediators of fibrotic disease in IFNγR-/- mice.

Neutrophil elastase promotes myofibroblast differentiation in lung fibrosis

IPF is a progressive lung disorder characterized by fibroblast proliferation and myofibroblast differentiation. Although neutrophil accumulation within IPF lungs has been negatively correlated with outcomes, the role played by neutrophils in lung fibrosis remains poorly understood. We have demonstrated previously that NE promotes lung cancer cell proliferation and hypothesized that it may have a similar effect on fibroblasts. In the current study, we show that NE(-/-) mice are protected from asbestos-induced lung fibrosis. NE(-/-) mice displayed reduced fibroblast and myofibroblast content when compared with controls. NE directly both lung fibroblast proliferation and myofibroblast differentiation in vitro, as evidenced by proliferation assays, collagen gel contractility assays, and αSMA induction. Furthermore, αSMA induction occurs in a TGF-β-independent fashion. Treatment of asbestos-recipient mice with ONO-5046, a synthetic NE antagonist, reduced hydroxyproline content. Thus, the current study points to a key role for neutrophils and NE in the progression of lung fibrosis. Lastly, the study lends rationale to use of NE-inhibitory approaches as a novel therapeutic strategy for patients with lung fibrosis.

The pathogenesis of bleomycin-induced lung injury in animals and its applicability to human idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease of unknown etiology, for which there is no curative pharmacological therapy. Bleomycin, an anti-neoplastic agent that causes lung fibrosis in human patients has been used extensively in rodent models to mimic IPF. In this review, we compare the pathogenesis and histological features of human IPF and bleomycin-induced pulmonary fibrosis (BPF) induced in rodents by intratracheal delivery. We discuss the current understanding of IPF and BPF disease development, from the contribution of alveolar epithelial cells and inflammation to the role of fibroblasts and cytokines, and draw conclusions about what we have learned from the intratracheal bleomycin model of lung fibrosis.

The anti-angiogenic role of discoidin domain receptor 2 (DDR2) in laser-induced choroidal neovascularization

Choroidal neovascularization (CNV), an aberrant growth of blood vessels in the choroid layer of the eye, is a major cause of vision loss. In view of our recent finding that discoidin domain receptor 2 (DDR2), a collagen-binding receptor tyrosine kinase, is involved in control of vascular endothelial activity and tumor angiogenesis, the present study aims to investigate whether and how DDR2 affects the pathogenesis of CNV. We initially found that a spontaneous DDR2 mutant mouse colony (slie) exhibited enhanced amplitude of laser-induced CNV. The inhibitory role of DDR2 in CNV development was further confirmed by experiments through intravitreous injection of DDR2 small interference RNA (siRNA) or DDR2-expressing adenovirus. Quantitative real-time polymerase chain reaction (qPCR) and immunoblot analysis showed that DDR2 regulates the expression of several major pro-angiogenic factors in the laser-injured choroid as well as in retinal pigment epithelium (RPE) cells. In addition, it was demonstrated that the CNV-induced increases in the phosphorylation levels of Akt and mTOR were affected by the upregulation or downregulation of DDR2. Thus, the data from this study for the first time revealed that DDR2 negatively regulates the development of experimental CNV in vivo, which may provide a novel target for preventing human pathological ocular neovascularization. Key messages: DDR2 does not affect retinal development. DDR2 inhibits laser-induced CNV. DDR2 regulates angiogenic factor expression in CNV lesion as well as in RPE cells. DDR2 is involved in modulation of CNV-induced activation of PI3K pathway.

P53, Bcl-2 and CD68 expression in response to amethopterin-induced lung injury and ameliorating role of L-carnitine

Amethopterin (methotrexate, MTX) is an antimetabolite and antifolate drug with antiflammatory properities and is used to treat autoimmune diseases, such as psoriasis, rheumatoid arthritis and certain types of cancer, such as breast, lymphoma and lung. The present study aimed to study the changes in P53, Bcl-2 and CD68 expression in response to amethopterin-induced lung injury and ameliorating the role of l-carnitine. A total of 36 male albino rats were equally divided into six groups: the first and second groups were the control and l-carnitine groups respectively while the 3rd group was amethopterin rat group; the 4th and 5th groups were co- and post-treated amethopterin rat with l-carnitine respectively and the 6th group was self treated amethopterin rat group. Our results shows that lung in amethopterin-treated rats showed many of histopathological alterations as severe to strong alveolar damage in the form of collapsed alveoli and strong thickened interalveolar septa with heavy infiltration of inflammatory cells. This damage was increased or remaining in self-amethopterin-treated group. Treatment (co- and post) with l-carnitine were improved in the lung structure that was treated with amethopterin. A significant increase in p53 and CD68 and decrease in Bc1-2 immunoreactivity in the lung in amethopterin group is observed when compared with the control group. However, treatment of rats with l-carnitine decreased the intensity of P53-ir and CD68-ir and increased the intensity of Bcl-2 in lung when compared with amethopterin rat group. Co-treatment with l-carnitine improved lung damage induced with amethopterin.

Mononuclear phagocytes and airway epithelial cells: novel sources of matrix metalloproteinase-8 (MMP-8) in patients with idiopathic pulmonary fibrosis

Objectives

Matrix metalloproteinase-8 (MMP-8) promotes lung fibrotic responses to bleomycin in mice. Although prior studies reported that MMP-8 levels are increased in plasma and bronchoalveolar lavage fluid (BALF) samples from IPF patients, neither the bioactive forms nor the cellular sources of MMP-8 in idiopathic pulmonary fibrosis (IPF) patients have been identified. It is not known whether MMP-8 expression is dys-regulated in IPF leukocytes or whether MMP-8 plasma levels correlate with IPF outcomes. Our goal was to address these knowledge gaps.

Methods

We measured MMP-8 levels and forms in blood and lung samples from IPF patients versus controls using ELISAs, western blotting, and qPCR, and assessed whether MMP-8 plasma levels in 73 IPF patients correlate with rate of lung function decline and mortality. We used immunostaining to localize MMP-8 expression in IPF lungs. We quantified MMP-8 levels and forms in blood leukocytes from IPF patients versus controls.

Results

IPF patients have increased BALF, whole lung, and plasma levels of soluble MMP-8 protein. Active MMP-8 is the main form elevated in IPF lungs. MMP-8 mRNA levels are increased in monocytes from IPF patients, but IPF patients and controls have similar levels of MMP-8 in PMNs. Surprisingly, macrophages and airway epithelial cells are the main cells expressing MMP-8 in IPF lungs. Plasma and BALF MMP-8 levels do not correlate with decline in lung function and/or mortality in IPF patients.

Conclusion

Blood and lung MMP-8 levels are increased in IPF patients. Active MMP-8 is the main form elevated in IPF lungs. Surprisingly, blood monocytes, lung macrophages, and airway epithelial cells are the main cells in which MMP-8 is upregulated in IPF patients. Plasma and BALF MMP-8 levels are unlikely to serve as a prognostic biomarker for IPF patients. These results provide new information about the expression patterns of MMP-8 in IPF patients.

Neonatal hyperoxia increases sensitivity of adult mice to bleomycin-induced lung fibrosis

Supplemental oxygen used to treat infants born prematurely constitutes a major risk factor for long-term deficits in lung function and host defense against respiratory infections. Likewise, neonatal oxygen exposure results in alveolar simplification in adult mice, and enhances leukocyte recruitment and fibrosis when adult mice are infected with a sublethal dose of influenza A virus. Because pulmonary fibrosis was not observed in infected adult mice exposed to room air as neonates, previous neonatal oxygen exposure may have reprogrammed how the adult lung responds to epithelial injury. By administering bleomycin to adult mice exposed to room air or hyperoxia as neonates, we tested the hypothesis that neonatal hyperoxia enhances fibrosis when the epithelium is injured by direct fibrotic stimulus. Increased sensitivity to bleomycin-induced lung fibrosis was observed in adult mice exposed to neonatal hyperoxia, and was associated with increased numbers of leukocytes and an accumulation of active transforming growth factor (TGF)-β1 in the lung. Fate mapping of the respiratory epithelium revealed that the epithelial-mesenchymal transition was not a significant source of fibroblasts in room air-exposed or oxygen-exposed mice treated with bleomycin. Instead, the treatment of mice with anti-Gr-1 antibody that depletes neutrophils and myeloid-derived suppressor cells reduced the early activation of TGF-β1 and attenuated hyperoxia-enhanced fibrosis. Because bleomycin and influenza A virus both cause epithelial injury, understanding how neonatal hyperoxia reprograms the epithelial response to these two different injurious agents could lead to new therapeutic opportunities for treating lung diseases attributed to prematurity.

The pathogenesis of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with an appalling prognosis. The failure of anti-inflammatory therapies coupled with the observation that deranged epithelium overlies proliferative myofibroblasts to form the fibroblastic focus has lead to the emerging concept that IPF is a disease of deregulated epithelial-mesenchymal crosstalk. IPF is triggered by an as yet unidentified alveolar injury that leads to activation of transforming growth factor-β (TGF-β) and alveolar basement membrane disruption. In the presence of persisting injurious pathways, or disrupted repair pathways, activated TGF-β can lead to enhanced epithelial apoptosis and epithelial-to-mesenchymal transition (EMT) as well as fibroblast, and fibrocyte, transformation into myofibroblasts which are resistant to apoptosis. The resulting deposition of excess disrupted matrix by these myofibroblasts leads to the development of IPF.

Therapeutic effects of evasin-1, a chemokine binding protein, in bleomycin-induced pulmonary fibrosis

CC chemokines play an important role in the pathogenesis of idiopathic pulmonary fibrosis. Few studies have evaluated the efficacy of therapeutically targeting CC chemokines and their receptors during interstitial lung diseases. In the present study, the therapeutic effects of Evasin-1, a tick-derived chemokine-binding protein that has high affinity for CCL3/microphage inflammatory protein (MIP)-1α, was investigated in a murine model of bleomycin-induced lung fibrosis. CCL3/MIP-1α concentrations in lung homogenates increased significantly with time after bleomycin challenge, and this was accompanied by increased number of leukocytes and elevated levels of CCL2/monocyte chemoattractant protein (MCP)-1, CCL5/regulated upon activation, normal T cell expressed and secreted, TNF-α and transforming growth factor-β(1), and pulmonary fibrosis. Administration of evasin-1 on a preventive (from the day of bleomycin administration) or therapeutic (from Day 8 after bleomycin) schedule decreased number of leukocytes in the lung, reduced levels of TNF-α and transforming growth factor-β(1), and attenuated lung fibrosis. These protective effects were similar to those observed in CCL3/MIP-1α-deficient mice. In conclusion, targeting CCL3/MIP-1α by treatment with evasin-1 is beneficial in the context of bleomycin-induced lung injury, even when treatment is started after the fibrogenic insult. Mechanistically, evasin-1 treatment was associated with decreased recruitment of leukocytes and production of fibrogenic cytokines. Modulation of CCL3/MIP-1α function by evasin-1 could be useful for the treatment of idiopathic pulmonary fibrosis.