New approaches to modulating idiopathic pulmonary fibrosis

Pan-Phosphodiesterase Inhibitors Attenuate TGF-β-Induced Pro-Fibrotic Phenotype in Alveolar Epithelial Type II Cells by Downregulating Smad-2 Phosphorylation

Airway remodeling is a pathological process that accompanies many chronic lung diseases. One of the important players in this process are epithelial cells, which under the influence of pro-inflammatory and pro-fibrotic factors present in the airway niche, actively participate in the remodeling process by increasing extracellular matrix secretion, acquiring migration properties, and overproducing pro-fibrotic transducers. Here, we investigated the effect of three new 8-arylalkylamino- and 8-alkoxy-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl-N-(5-(tert-butyl)-2-hydroxyphenyl)butanamides (1, 2, and 3), representing prominent pan-phosphodiesterase (pan-PDE) inhibitors on transforming growth factor type β (TGF-β)-induced alveolar epithelial type II cells (A549 cell line) of a pro-fibrotic phenotype. Our results demonstrate for the first time the strong activity of pan-PDE inhibitors in the prevention of TGF-β-induced mesenchymal markers’ expression and A549 cells’ migration. We also showed an increased p-CREB and decreased p-Smad-2 phosphorylation in TGF-β-induced A549 cells treated with 1, 2, and 3 derivatives, thereby confirming a pan-PDE inhibitor mesenchymal phenotype reducing effect in alveolar epithelial type II cells via suppression of the canonical Smad signaling pathway. Our observations confirmed that PDE inhibitors, and especially those active against various isoforms involved in the airway remodeling, constitute an interesting group of compounds modulating the pro-fibrotic response of epithelial cells.

The phosphodiesterase 4 inhibitor AA6216 suppresses activity of fibrosis-specific macrophages

Background

Idiopathic pulmonary fibrosis (IPF) is a form of chronic, progressive fibrosing interstitial pneumonia of unknown cause, with a poor prognosis. We previously showed the antifibrotic effects of a novel phosphodiesterase 4 (PDE4) inhibitor, AA6216. In this study, we examined the effect of AA6216 on the pulmonary accumulation of segregated-nucleus-containing atypical monocytes (SatMs), which produce tumor necrosis factor (TNF)-α and are involved in murine lung fibrosis.

Methods

Mice were treated with bleomycin intratracheally at day 0 and either 10 mg/kg AA6216, 100 mg/kg nintedanib, or vehicle orally once daily from day 0 to 8. On day 9, we isolated the bronchoalveolar lavage fluid and analyzed the SatM ratio. In addition, we evaluated the effect of AA6216 on TNF-α production from SatMs isolated from murine bone marrow.

Results

AA6216, and not the antifibrotic agent nintedanib, significantly suppressed the pulmonary accumulation of SatMs (AA6216: 68.3 ± 5.4%, Nintedanib: 129.8 ± 19.7%). Furthermore, AA6216 dose-dependently inhibited the production of TNF-α by SatMs.

Conclusions

AA6216 suppresses pathogenic SatMs in the lung, which contributes to its antifibrotic effects.

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Fibrosis-specific macrophages are critical for the development of lung fibrosis.

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The PDE4 inhibitor, AA6216, suppresses the pro-fibrotic activity of macrophages.

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AA6216 inhibits the pulmonary accumulation of fibrosis-specific macrophages.

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AA6216 inhibits the production of TNF-α by fibrosis-specific macrophages.

Combined analysis of serum SAP and PRSS2 for the differential diagnosis of CD and UC

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory disease. Crone's disease (CD) and ulcerative colitis (UC) are types of IBD. There is a need for a more accurate, noninvasive biomarker to distinguish CD from UC.

PURPOSE

To verify the diagnostic value of combined serum trypsin 2 (PRSS2) and serum amyloid P component (SAP) evaluation in distinguishing CD from UC.

METHODS

The subjects included 28 normal controls (NC) as well as 44 UC, 72CD, 16 colorectal cancer (CRC), 10 colorectal polyps, and 10 cancer cases. Serum SAP, PRSS2, CRP, and CEA were measured and compared.

RESULTS

The concentration of CEA in CRC and other gastrointestinal tumors was significantly higher than that in UC, CD, and colorectal polyps. The concentration of CRP was significantly higher in UC and CD than that in the healthy group, but there were no significant differences when compared to the intestinal polyp group. Serum PRSS2 concentration was significantly higher in the UC and CD groups than that in the colorectal polyp group, and the average serum concentration of SAP in CD was significantly higher compared to UC. In patients with colorectal polyps, there was no correlation between PRSS2 and CRP. ROC curve analysis showed that the AUC of PRSS2 used to distinguish IBD patients from healthy controls or colorectal polyp patients was 0.730 and 0.774, respectively. The AUC of SAP used to distinguish CD from UC was 0.706. The AUC of combined PRSS2 and SAP was not different from the AUC for individual SAP. Finally, we demonstrated that the expression of SAP in CD patient tissues was significantly higher than that in UC patients.

CONCLUSION

The combined analysis of serum SAP and PRSS2 has differential diagnostic value for CD and UC.

A novel phosphodiesterase 4 inhibitor, AA6216, reduces macrophage activity and fibrosis in the lung

Idiopathic pulmonary fibrosis (IPF) is an intractable disease with poor prognosis, and therapeutic options are limited. While the pathogenic mechanism is unknown, cytokines, such as transforming growth factor (TGF)-β, and immune cells, such as monocytes and macrophages, that produce them, seem to be involved in fibrosis. Some phosphodiesterase 4 (PDE4) inhibitors reportedly have anti-fibrotic potential by acting on these disease-related factors. Therefore, we evaluated the effect of a novel PDE4 inhibitor, AA6216, on nonclinical IPF-related models and samples from IPF patients. First, we examined the inhibitory effect of AA6216 on the production of TGF-β1 from a human monocytic cell line, THP-1. Second, we analyzed the impact of AA6216 on TNF-α production by human alveolar macrophages collected from patients with IPF. Finally, we investigated the anti-fibrotic potency of AA6216 on bleomycin-induced lung fibrosis in mice. We found that AA6216 significantly inhibited TGF-β1 production by THP-1 cells. It also significantly suppressed TNF-α production by alveolar macrophages from patients with IPF. In the mouse model of bleomycin-induced pulmonary fibrosis, therapeutic administration of AA6216 significantly reduced fibrosis scores, collagen-stained areas, and TGF-β1 in bronchoalveolar lavage fluid. AA6216 may represent a new agent for the treatment of IPF with a distinct mechanism of action from that of conventional anti-fibrotic agents.

Insights into the Role of Bioactive Food Ingredients and the Microbiome in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease mainly associated with aging and, to date, its causes are still largely unknown. It has been shown that dietary habits can accelerate or delay the occurrence of aging-related diseases; however, their potential role in IPF development has been underestimated so far. The present review summarizes the evidence regarding the relationship between diet and IPF in humans, and in animal models of pulmonary fibrosis, in which we discuss the bioactivity of specific dietary food ingredients, including fatty acids, peptides, amino acids, carbohydrates, vitamins, minerals and phytochemicals. Interestingly, many animal studies reveal preventive and therapeutic effects of particular compounds. Furthermore, it has been recently suggested that the lung and gut microbiota could be involved in IPF, a relationship which may be linked to changes in immunological and inflammatory factors. Thus, all the evidence so far puts forward the idea that the gut-lung axis could be modulated by dietary factors, which in turn have an influence on IPF development. Overall, the data reviewed here support the notion of identifying food ingredients with potential benefits in IPF, with the ultimate aim of designing nutritional approaches as an adjuvant therapeutic strategy.

Inhibiting eicosanoid degradation exerts antifibrotic effects in a pulmonary fibrosis mouse model and human tissue

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a disease with high 5-year mortality and few therapeutic options. Prostaglandin (PG) E₂ exhibits antifibrotic properties and is reduced in bronchoalveolar lavage from patients with IPF. 15-Prostaglandin dehydrogenase (15-PGDH) is the key enzyme in PGE₂ metabolism under the control of TGF-β and microRNA 218.

OBJECTIVE

We sought to investigate the expression of 15-PGDH in IPF and the therapeutic potential of a specific inhibitor of this enzyme in a mouse model and human tissue.

METHODS

In vitro studies, including fibrocyte differentiation, regulation of 15-PGDH, RT-PCR, and Western blot, were performed using peripheral blood from healthy donors and patients with IPF and A549 cells. Immunohistochemistry, immunofluorescence, 15-PGDH activity assays, and in situ hybridization as well as ex vivo IPF tissue culture experiments were done using healthy donor and IPF lungs. Therapeutic effects of 15-PGDH inhibition were studied in the bleomycin mouse model of pulmonary fibrosis.

RESULTS

We demonstrate that 15-PGDH shows areas of increased expression in patients with IPF. Inhibition of this enzyme increases PGE₂ levels and reduces collagen production in IPF precision cut lung slices and in the bleomycin model. Inhibitor-treated mice show amelioration of lung function, decreased alveolar epithelial cell apoptosis, and fibroblast proliferation. Pulmonary fibrocyte accumulation is also decreased by inhibitor treatment in mice, similar to PGE₂ that inhibits fibrocyte differentiation from blood of healthy donors and patients with IPF. Finally, microRNA 218-5p, which is downregulated in patients with IPF, suppressed 15-PGDH expression in vivo and in vitro.

CONCLUSIONS

These findings highlight the role of 15-PGDH in IPF and suggest 15-PGDH inhibition as a promising therapeutic approach.

Feifukang ameliorates pulmonary fibrosis by inhibiting JAK-STAT signaling pathway

Background

Feifukang (FFK) is a traditional Chinese medicine composed of herbs that protect lung function. However, difficulty arises regarding the clinical application of FFK due to the complex mechanism of Chinese medicines. This study aimed to investigate the efficacy of FFK and explore its targeted genes and pathways.

Methods

Histopathological changes and collagen deposition were measured to evaluate the effect of FFK on bleomycin-induced pulmonary fibrosis in mice. The differentially expressed targeted genes and pathways were first screened using RNA sequencing. Then network pharmacology and other experiments were conducted to confirm RNA sequencing data.

Results

FFK treatment reduced the pathological score and collagen deposition, with a decrease in α-SMA and collagen. RNA sequencing and network pharmacology results all showed that FFK can ameliorate pulmonary fibrosis through multi-genes and multi-pathways. The targeted genes in JAK-STAT signaling pathway are some of the most notable components of these multi-genes and multi-pathways. Further experiments illustrated that FFK regulated phosphorylation of SMAD3, STAT3 and JAK1, and their co-expressed lncRNAs, which all are the important genes in JAK-STAT signaling pathway.

Conclusion

FFK can ameliorate pulmonary fibrosis by inhibiting JAK-STAT signaling pathway and has potential therapeutic value for lung fibrosis treatment. Our study provides a new idea for the study of traditional Chinese medicine.

Induced Pluripotent Stem Cells Inhibit Bleomycin-Induced Pulmonary Fibrosis in Mice through Suppressing TGF-β1/Smad-Mediated Epithelial to Mesenchymal Transition

Pulmonary fibrosis is a progressive and irreversible fibrotic lung disorder with high mortality and few treatment options. Recently, induced pluripotent stem (iPS) cells have been considered as an ideal resource for stem cell-based therapy. Although, an earlier study demonstrated the therapeutic effect of iPS cells on pulmonary fibrosis, the exact mechanisms remain obscure. The present study investigated the effects of iPS cells on inflammatory responses, transforming growth factor (TGF)-β1 signaling pathway, and epithelial to mesenchymal transition (EMT) during bleomycin (BLM)-induced lung fibrosis. A single intratracheal instillation of BLM (5 mg/kg) was performed to induce pulmonary fibrosis in C57BL/6 mice. Then, iPS cells (c-Myc-free) were administrated intravenously at 24 h following BLM instillation. Three weeks after BLM administration, pulmonary fibrosis was evaluated. As expected, treatment with iPS cells significantly limited the pathological changes, edema, and collagen deposition in lung tissues of BLM-induced mice. Mechanically, treatment with iPS cells obviously repressed the expression ratios of matrix metalloproteinase-2 (MMP-2) to its tissue inhibitor -2 (TIMP-2) and MMP-9/TIMP-1 in BLM-induced pulmonary tissues. In addition, iPS cell administration remarkably suppressed BLM-induced up-regulation of pulmonary inflammatory mediators, including tumor necrosis factor-α, interleukin (IL)-1β, IL-6, inducible nitric oxide synthase, nitric oxide, cyclooxygenase-2 and prostaglandin E₂. We further demonstrated that transplantation of iPS cells markedly inhibited BLM-mediated activation of TGF-β1/Mothers against decapentaplegic homolog 2/3 (Smad2/3) and EMT in lung tissues through up-regulating epithelial marker E-cadherin and down-regulating mesenchymal markers including fibronectin, vimentin and α-smooth muscle actin. Moreover, in vitro, iPS cell-conditioned medium (iPSC-CM) profoundly inhibited TGF-β1-induced EMT signaling pathway in mouse alveolar epithelial type II cells (AECII). Collectively, our results suggest that transplantation of iPS cells could suppress inflammatory responses, TGF-β1/Smad2/3 pathway and EMT during the progression of BLM-induced pulmonary fibrosis, providing new useful clues regarding the mechanisms of iPS cells in the treatment for this disease.

Characterization of a novel model incorporating airway epithelial damage and related fibrosis to the pathogenesis of asthma

Asthma develops from injury to the airways/lungs, stemming from airway inflammation (AI) and airway remodeling (AWR), both contributing to airway hyperresponsiveness (AHR). Airway epithelial damage has been identified as a new etiology of asthma but is not targeted by current treatments. Furthermore, it is poorly studied in currently used animal models of AI and AWR. Therefore, this study aimed to incorporate epithelial damage/repair with the well-established ovalbumin (OVA)-induced model of chronic allergic airway disease (AAD), which presents with AI, AWR, and AHR, mimicking several features of human asthma. A 3-day naphthalene (NA)-induced model of epithelial damage/repair was superimposed onto the 9-week OVA-induced model of chronic AAD, before 6 weeks of OVA nebulization (NA+OVA group), during the second last OVA nebulization period (OVA/NA group) or 1 day after the 6-week OVA nebulization period (OVA+NA group), using 6-8-week-old female Balb/c mice (n=6-12/group). Mice subjected to the 9-week OVA model, 3-day NA model or respective vehicle treatments (saline and corn oil) were used as appropriate controls. OVA alone significantly increased epithelial thickness and apoptosis, goblet cell metaplasia, TGF-β1, subepithelial collagen (assessed by morphometric analyses of various histological stains), total lung collagen (hydroxyproline analysis), and AHR (invasive plethysmography) compared with that in saline-treated mice (all P<0.05 vs saline treatment). NA alone caused a significant increase in epithelial denudation and apoptosis, TGF-β1, subepithelial, and total lung collagen compared with respective measurements from corn oil-treated controls (all P<0.01 vs corn oil treatment). All three combined models underwent varying degrees of epithelial damage and AWR, with the OVA+NA model demonstrating the greatest increase in subepithelial/total lung collagen and AHR (all P<0.05 vs OVA alone or NA alone). These combined models of airway epithelial damage/AAD demonstrated that epithelial damage is a key contributor to AWR, fibrosis and related AHR, and augments the effects of AI on these parameters.

Persistent lung inflammation and fibrosis in serum amyloid P component (APCs-/-) knockout mice

Fibrosing diseases, such as pulmonary fibrosis, cardiac fibrosis, myelofibrosis, liver fibrosis, and renal fibrosis are chronic and debilitating conditions and are an increasing burden for the healthcare system. Fibrosis involves the accumulation and differentiation of many immune cells, including macrophages and fibroblast-like cells called fibrocytes. The plasma protein serum amyloid P component (SAP; also known as pentraxin-2, PTX2) inhibits fibrocyte differentiation in vitro, and injections of SAP inhibit fibrosis in vivo. SAP also promotes the formation of immuno-regulatory Mreg macrophages. To elucidate the endogenous function of SAP, we used bleomycin aspiration to induce pulmonary inflammation and fibrosis in mice lacking SAP. Compared to wildtype C57BL/6 mice, we find that in Apcs^-/- “SAP knock-out” mice, bleomycin induces a more persistent inflammatory response and increased fibrosis. In both C57BL/6 and Apcs^-/- mice, injections of exogenous SAP reduce the accumulation of inflammatory macrophages and prevent fibrosis. The types of inflammatory cells present in the lungs following bleomycin-aspiration appear similar between C57BL/6 and Apcs^-/- mice, suggesting that the initial immune response is normal in the Apcs^-/- mice, and that a key endogenous function of SAP is to promote the resolution of inflammation and fibrosis.