The Bleomycin Model of Pulmonary Fibrosis

Total flavonoids of Oxytropis falcata Bunge have a positive effect on idiopathic pulmonary fibrosis by inhibiting the TGF-β1/Smad signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease with unknown etiology. Oxytropis falcata Bunge (O. falcata) is a 1-35 cm high perennial clustered herb, also known as edaxia, has viscosity and a special smell, and is mainly distributed in the western areas of China. The root of O. falcata has a diameter of 6 mm, is straight and deep, dark red and its stems are shortened, woody and multibranched. O. falcata has heat-clearing, detoxification, analgesic, anti-inflammatory, antibacterial, hemostatic and antitumor activities. Furthermore, O. falcata has excellent anti-inflammatory and analgesic effects, and it is one of the three major anti-inflammatory drugs in Tibetan medicine, known as "the king of herbs". Total flavonoids of Oxytropis falcata Bunge (FOFB) were previously extracted, and their pharmacological activities are consistent with those of the whole herb. In this study, FOFB was extracted from O. falcata by ethanol extraction, and the mechanism of FOFB on IPF was verified by in vivo and in vitro experiments.

AIM OF THE STUDY

In this study, we aimed to observe the effects of FOFB on idiopathic pulmonary fibrosis.

MATERIALS AND METHODS

In in vivo experiments, an IPF rat model was established by bleomycin induction. The rats were treated with FOFB (100, 200, 400 mg kg^-1·d^-1) for 4 weeks. Masson staining and the expression of TGF-β, p-Smad2, p-Smad3 and Smad7 in the lung tissue of rats were detected. In in vitro experiments, we perfused normal rats with FOFB (100, 200, 400 mg kg^-1·d^-1) and obtained the corresponding drug-containing serum. The HFL-1 cell model induced by TGF-β1 was used to detect the corresponding indices through intervention with drug-containing serum. The best intervention time for drug-containing serum was detected by the CCK-8 method. Changes in apoptosis, cytoskeleton and rough endoplasmic reticulum structure were detected. Finally, the expression of TGF-β, p-Smad2, p-Smad3 and Smad7 in cells was examined.

RESULTS

In vivo, Masson staining indicated that the degree of pulmonary fibrosis increased significantly, the expression of TGF-β, p-smad2 and p-Smad3 increased significantly, and the expression of Smad7 decreased in the model group. We found that the degree of pulmonary fibrosis gradually decreased and that the inhibition of the TGF-β/Smad signaling pathway became more obvious with increasing FOFB dose. FOFB (400 mg kg^-1·d^-1) significantly improved the degree of pulmonary fibrosis in rats. In in vitro experiments, the CCK-8 results showed that 120 h was the best intervention time for drug-containing serum. In the model group, there was no obvious apoptosis or changes in microfilaments and microtubules, the number of rough endoplasmic reticulum increased, and the expression of TGF-β, p-Smad2 and p-Smad3 increased significantly, while the expression of Smad7 decreased significantly. We found that with the increase in drug-containing serum concentration, the apoptosis, cytoskeleton and degree of destruction of the rough endoplasmic reticulum in the HFL-1 cell model also increased, and the inhibition of the TGF-β/Smad signaling pathway became more pronounced; the effect of the drug-containing serum administered with FOFB (400 mg kg^-1·d^-1) was the most significant.

CONCLUSIONS

The results suggest that FOFB can improve the occurrence and development of IPF. The effect of FOFB on IPF may be mediated by inhibition of the TGF-β1/Smad signaling pathway.

Myeloid Fbxw7 Prevents Pulmonary Fibrosis by Suppressing TGF-β Production

Idiopathic pulmonary fibrosis (IPF) is a group of chronic interstitial pulmonary diseases characterized by an inexorable decline in lung function with limited treatment options. The abnormal expression of transforming growth factor-β (TGF-β) in profibrotic macrophages is linked to severe pulmonary fibrosis, but the regulation mechanisms of TGF-β expression are incompletely understood. We found that decreased expression of E3 ubiquitin ligase Fbxw7 in peripheral blood mononuclear cells (PBMCs) was significantly related to the severity of pulmonary fibrosis in IPF patients. Fbxw7 is identified to be a crucial suppressing factor for pulmonary fibrosis development and progression in a mouse model induced by intratracheal bleomycin treatment. Myeloid cell-specific Fbxw7 deletion increases pulmonary monocyte-macrophages accumulation in lung tissue, and eventually promotes bleomycin-induced collagen deposition and progressive pulmonary fibrosis. Notably, the expression of TGF-β in profibrotic macrophages was significantly upregulated in myeloid cell-specific Fbxw7 deletion mice after bleomycin treatment. C-Jun has long been regarded as a critical transcription factor of Tgfb1, we clarified that Fbxw7 inhibits the expression of TGF-β in profibrotic macrophages by interacting with c-Jun and mediating its K48-linked ubiquitination and degradation. These findings provide insight into the role of Fbxw7 in the regulation of macrophages during the pathogenesis of pulmonary fibrosis.

Syndecan-2 regulates PAD2 to exert antifibrotic effects on RA-ILD fibroblasts

Rheumatoid arthritis (RA)-associated interstitial lung disease (RA-ILD) is the most common pulmonary complication of RA, increasing morbidity and mortality. Anti-citrullinated protein antibodies have been associated with the development and progression of both RA and fibrotic lung disease; however, the role of protein citrullination in RA-ILD remains unclear. Here, we demonstrate that the expression of peptidylarginine deiminase 2 (PAD2), an enzyme that catalyzes protein citrullination, is increased in lung homogenates from subjects with RA-ILD and their lung fibroblasts. Chemical inhibition or genetic knockdown of PAD2 in RA-ILD fibroblasts attenuated their activation, marked by decreased myofibroblast differentiation, gel contraction, and extracellular matrix gene expression. Treatment of RA-ILD fibroblasts with the proteoglycan syndecan-2 (SDC2) yielded similar antifibrotic effects through regulation of PAD2 expression, phosphoinositide 3-kinase/Akt signaling, and Sp1 activation in a CD148-dependent manner. Furthermore, SDC2-transgenic mice exposed to bleomycin-induced lung injury in an inflammatory arthritis model expressed lower levels of PAD2 and were protected from the development of pulmonary fibrosis. Together, our results support a SDC2-sensitive profibrotic role for PAD2 in RA-ILD fibroblasts and identify PAD2 as a promising therapeutic target of RA-ILD.

Matrix Metalloproteinase 7 Expression and Apical Epithelial Defects in Atp8b1 Mutant Mouse Model of Pulmonary Fibrosis

Abnormalities in airway epithelia and lung parenchyma are found in Atp8b1 mutant mice, which develop pulmonary fibrosis after hyperoxic insult. Microarray and ingenuity pathway analysis (IPA) show numerous transcripts involved in ciliogenesis are downregulated in 14-month (14 M) -old Atp8b1 mouse lung compared with wild-type C57BL/6. Lung epithelium of Atp8b1 mice demonstrate apical abnormalities of ciliated and club cells in the bronchial epithelium on transmission electron microscopy (TEM). Matrix metalloproteinase 7 (MMP7) regulates of ciliogenesis and is a biomarker for idiopathic pulmonary fibrosis (IPF) in humans. Mmp7 transcript and protein expression are significantly upregulated in 14 M Atp8b1 mutant mouse lung. MMP7 expression is also increased in bronchoalveolar lavage fluid (BAL). Immunohistochemistry is localized MMP7 to bronchial epithelial cells in the Atp8b1 mutant. In conclusion, MMP7 is upregulated in the aged Atp8b1 mouse model, which displays abnormal ciliated cell and club cell morphology. This mouse model can facilitate the exploration of the role of MMP7 in epithelial integrity and ciliogenesis in IPF. The Atp8b1 mutant mouse is proposed as a model for IPF.

p62-Nrf2 Regulatory Loop Mediates the Anti-Pulmonary Fibrosis Effect of Bergenin

Idiopathic pulmonary fibrosis (IPF) can severely disrupt lung function, leading to fatal consequences, and there is currently a lack of specific therapeutic drugs. Bergenin is an isocoumarin compound with lots of biological functions including antioxidant activity. This study evaluated the potential beneficial effects of bergenin on pulmonary fibrosis and investigated the possible mechanisms. We found that bergenin alleviated bleomycin-induced pulmonary fibrosis by relieving oxidative stress, reducing the deposition of the extracellular matrix (ECM) and inhibiting the formation of myofibroblasts. Furthermore, we showed that bergenin could induce phosphorylation and expression of p62 and activation of Nrf2, Nrf2 was required for bergenin-induced p62 upregulation, and p62 knockdown reduced bergenin-induced Nrf2 activity. More importantly, knockdown of Nrf2 or p62 could abrogate the antioxidant activity of bergenin and the inhibition effect of bergenin on TGF-β-induced ECM deposition and myofibroblast differentiation. Thereby, a regulatory loop is formed between p62 and Nrf2, which is an important target for bergenin aimed at treating pulmonary fibrosis.

Esomeprazole alleviates fibrosis in systemic sclerosis by modulating AhR/Smad2/3 signaling

Systemic sclerosis (SSc) is a connective tissue disease with the involvement of complex signaling pathways, such as TGF-β/Smad2/3. SSc can lead to severe multiple organ fibrosis, but no effective therapy is currently available because of its unclear pathogenesis. Exploring new treatments is the focus of recent research on SSc. Recent studies have implied a potential antifibrotic role of esomeprazole (ESO), but with currently unidentified mechanisms. Signaling of AhR, a ligand-dependent transcription factor, has been described as a key controller of fibrosis, tumorigenesis, and immune balance. Recently, it has been reported that ESO may be an exogenous agonist of AhR signaling, while no previous study has revealed the effects of ESO on SSc and its underlying mechanisms. In this study, we demonstrate that ESO suppresses the migration of SSc dermal fibroblasts, downregulates profibrotic markers, including COLIA1, α-SMA CTGF and MMP1, and limits collagen production potentially via the activation of AhR signaling. More importantly, ESO could block Smad2/3 phosphorylation concurrently with the reduction in collagen via AhR signaling. Moreover, our results from the bleomycin (BLM)-induced SSc model in skin and lung shows that ESO ameliorates fibrosis in vivo, which in keeping with our in vitro results. We conclude that ESO is a potential therapeutic drug for SSc fibrosis.

Cell Origin and iNOS Function Are Critical to Macrophage Activation Following Acute Lung Injury

In the intratracheal bleomycin (ITB) model of acute lung injury (ALI), macrophages are recruited to the lung and participate in the inflammation and resolution that follows injury. Macrophage origin is influential in determining activation; however, the specific phenotype of recruited and resident macrophages is not known. Inducible nitric oxide synthase (iNOS) has been implicated in the pathogenesis of ALI; however, the effects of its inhibition are mixed. Here we examined how macrophage origin determines the phenotypic response to ALI. Further, we hypothesize cell specific iNOS is key to determining activation and recruitment. Using a chimeric mouse approach, we have identified recruited and resident macrophage populations. We also used the chimeric mouse approach to create either pulmonary or bone marrow NOS2^-/- mice and systemically inhibited iNOS via 1400 W. We evaluated macrophage populations at the peak of inflammation (8 days) and the beginning of resolution (15 days) following ITB. These studies demonstrate tissue resident macrophages adopt a M2 phenotype specifically, but monocyte originated macrophages activate along a spectrum. Additionally, we demonstrated that monocyte originating macrophage derived iNOS is responsible for recruitment to the lung during the inflammatory phase. Further, we show that macrophage activation is dependent upon cellular origin. Finally, these studies suggest pulmonary derived iNOS is detrimental to the lung following ITB. In conclusion, macrophage origin is a key determinant in response to ALI and iNOS is central to recruitment and activation.

Nuclear respiratory factor-1 negatively regulates TGF-β1 and attenuates pulmonary fibrosis

The preclinical model of bleomycin-induced lung fibrosis is useful to study mechanisms related to human pulmonary fibrosis. Using BLM in mice, we find low HO-1 expression. Although a unique Rhenium-CO-releasing molecule (ReCORM) up-regulates HO-1, NRF-1, CCN5, and SMAD7, it reduces TGFβ1, TGFβr1, collagen, α-SMA, and phosphorylated Smad2/3 levels in mouse lung and in human lung fibroblasts. ChIP assay studies confirm NRF-1 binding to the promoters of TGFβ1 repressors CCN5 and Smad7. ReCORM did not blunt lung fibrosis in Hmox1-deficient alveolar type 2 cell knockout mice, suggesting this gene participates in lung protection. In human lung fibroblasts, TGFβ1-dependent production of α-SMA is abolished by ReCORM or by NRF-1 gene transfection. We demonstrate effective HO-1/NRF-1 signaling in lung AT2 cells protects against BLM induced lung injury and fibrosis by maintaining mitochondrial health, function, and suppressing the TGFβ1 pathway. Thus, protection of AT2 cell mitochondrial integrity via HO-1/NRF-1 presents an innovative therapeutic target.

Latent Transforming Growth Factor-β Binding Protein-2 Regulates Lung Fibroblast-to-Myofibroblast Differentiation in Pulmonary Fibrosis via NF-κB Signaling

Despite past extensive studies, the mechanisms underlying pulmonary fibrosis (PF) still remain poorly understood. The aberrantly activated lung myofibroblasts, predominantly emerging through fibroblast-to-myofibroblast differentiation, are considered to be the key cells in PF, resulting in excessive accumulation of extracellular matrix (ECM). Latent transforming growth factor-β (TGFβ) binding protein-2 (LTBP2) has been suggested as playing a critical role in modulating the structural integrity of the ECM. However, its function in PF remains unclear. Here, we demonstrated that lungs originating from different types of patients with PF, including idiopathic PF and rheumatoid arthritis-associated interstitial lung disease, and from mice following bleomycin (BLM)-induced PF were characterized by increased LTBP2 expression in activated lung fibroblasts/myofibroblasts. Moreover, serum LTBP2 was also elevated in patients with COVID-19-related PF. LTBP2 silencing by lentiviral shRNA transfection protected against BLM-induced PF and suppressed fibroblast-to-myofibroblast differentiation in vivo and in vitro. More importantly, LTBP2 overexpression was able to induce differentiation of lung fibroblasts to myofibroblasts in vitro, even in the absence of TGFβ1. By further mechanistic analysis, we demonstrated that LTBP2 silencing prevented fibroblast-to-myofibroblast differentiation and subsequent PF by suppressing the phosphorylation and nuclear translocation of NF-κB signaling. LTBP2 overexpression-induced fibroblast-to-myofibroblast differentiation depended on the activation of NF-κB signaling in vitro. Therefore, our data indicate that intervention to silence LTBP2 may represent a promising therapy for PF.

Fibrotic lung disease inhibits innate immune responses to Staphylococcal pneumonia via impaired neutrophil and macrophage function

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease characterized by collagen deposition within the lung interstitium. Bacterial infection is associated with increased morbidity and more rapid mortality in IPF patient populations, and pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) are commonly isolated from the lungs of hospitalized patients with IPF. Despite this, the effects of fibrotic lung injury on critical immune responses to infection remain unknown. In the present study, we show that, like humans with IPF, fibrotic mice infected with MRSA exhibit increased morbidity and mortality compared with uninfected fibrotic mice. We determine that fibrosis conferred a defect in MRSA clearance compared with nonfibrotic mice, resulting from blunted innate immune responses. We show that fibrosis inhibited neutrophil intracellular killing of MRSA through impaired neutrophil elastase release and oxidative radical production. Additionally, we demonstrate that lung macrophages from fibrotic mice have impaired phagocytosis of MRSA. Our study describes potentially novel impairments of antimicrobial responses upon pulmonary fibrosis development, and our findings suggest a possible mechanism for why patients with IPF are at greater risk of morbidity and mortality related to infection.

Inhibition of aberrant tissue remodelling by mesenchymal stromal cells singly coated with soft gels presenting defined chemomechanical cues

The precise understanding and control of microenvironmental cues could be used to optimize the efficacy of cell therapeutics. Here, we show that mesenchymal stromal cells (MSCs) singly coated with a soft conformal gel presenting defined chemomechanical cues promote matrix remodelling by secreting soluble interstitial collagenases in response to the presence of tumour necrosis factor alpha (TNF-α). In mice with fibrotic lung injury, treatment with the coated MSCs maintained normal collagen levels, fibre density and microelasticity in lung tissue, and the continuous presentation of recombinant TNF-α in the gel facilitated the reversal of aberrant tissue remodelling by the cells when inflammation subsided in the host. Gel coatings with predefined chemomechanical cues could be used to tailor cells with specific mechanisms of action for desired therapeutic outcomes.

Effect and Mechanism of Qingfei Paidu Decoction in the Management of Pulmonary Fibrosis and COVID-19

Qingfei Paidu decoction (QFPD) has been repeatedly recommended for the clinical treatment of novel coronavirus disease 2019 (COVID-19) in multiple provinces throughout China. A possible complication of COVID-19 lung involvement is pulmonary fibrosis, which causes chronic breathing difficulties and affects the patient's quality of life. Therefore, there is an important question regarding whether QFPD can alleviate the process of pulmonary fibrosis and its potential mechanisms. To explore this issue, this study demonstrated the anti-pulmonary fibrosis activity and mode of action of QFPD in vivo and in vitro pulmonary fibrosis models and network pharmacology. The results showed that QFPD effectively ameliorated the bleomycin-induced inflammation and collagen deposition in mice and significantly improved the epithelial-mesenchymal transition in pulmonary fibrosis in mice. In addition, QFPD inhibited bleomycin-induced M2 polarization of macrophages in pulmonary tissues. An in-depth study of the mechanism of QFPD in the treatment of pulmonary fibrosis based on network pharmacology and molecular simulation revealed that SRC was the main target of QFPD and sitosterol (a key compound in QFPD). QFPD and sitosterol regulate the EMT process and M2 polarization of macrophages by inhibiting the activation of SRC, thereby alleviating pulmonary fibrosis in mice. COVID-19 infection might produce severe fibrosis, and antifibrotic therapy with QFPD may be valuable in preventing severe neocoronavirus disease in patients with IPF, which could be a key factor explaining the role of QFPD in the treatment of COVID-19.

Distinct roles of KLF4 in mesenchymal cell subtypes during lung fibrogenesis

During lung fibrosis, the epithelium induces signaling to underlying mesenchyme to generate excess myofibroblasts and extracellular matrix; herein, we focus on signaling in the mesenchyme. Our studies indicate that platelet-derived growth factor receptor (PDGFR)-β⁺ cells are the predominant source of myofibroblasts and Kruppel-like factor (KLF) 4 is upregulated in PDGFR-β⁺ cells, inducing TGFβ pathway signaling and fibrosis. In fibrotic lung patches, KLF4 is down-regulated, suggesting KLF4 levels decrease as PDGFR-β⁺ cells transition into myofibroblasts. In contrast to PDGFR-β⁺ cells, KLF4 reduction in α-smooth muscle actin (SMA)⁺ cells non-cell autonomously exacerbates lung fibrosis by inducing macrophage accumulation and pro-fibrotic effects of PDGFR-β⁺ cells via a Forkhead box M1 to C-C chemokine ligand 2-receptor 2 pathway. Taken together, in the context of lung fibrosis, our results indicate that KLF4 plays opposing roles in PDGFR-β⁺ cells and SMA⁺ cells and highlight the importance of further studies of interactions between distinct mesenchymal cell types.

A novel mouse wound model for scar tissue formation in abdominal muscle wall

Hypertrophic scars found on the human body rarely develop in experimental animals, possibly due to their looser skin structure. This makes it difficult to understand the genesis of scar lesions. Therefore, appropriate animal models are urgently needed. In this study, we established a novel experimental model of a scar-forming wound by resecting a small portion of the abdominal muscle wall on the lower center of the abdomen in C57BL/6N mice, which are exposed to contractive forces by the surrounding muscle tissue. As a low-tension control, a back skin excision model was used with a splint fixed onto the excised skin edge, and granulation tissue formed on the muscle fascia supported by the back skeleton. One week after the resection, initial healing reactions, such as fibroblast proliferation, occurred in both models. However, after 21 days, lesions with collagen-rich granulation tissues, which were also accompanied by multiple nodular/spherical-like structures, developed only in the abdominal wall model. These lesions were analogous to scar lesions in humans. Therefore, the animal model developed in this study is unique in that fibrous scar tissues form under physiological conditions without using any artificial factors and is valuable for studying the pathogenesis and preclinical treatment of scar lesions.

Antifibrotic effect of Gancao Ganjiang decoction is mediated by PD-1 / TGF-β1 / IL-17A pathway in bleomycin-induced idiopathic pulmonary fibrosis

ETHNOPHARMACOLOGICAL RELEVANCE

Firstly prescribed in the ancient Chinese book Jingui Yaolue, Gancao Ganjiang decoction (GGD) is a traditional Chinese herbal formula that has been widely used to treat "atrophic lung disease". GGD is a popular and widely used traditional Chinese medicine. The decoction is extracted from the dried rhizomes and roots of Glycyrrhiza uralensis Fisch. and Zingiber officinale Roscoe (2:1).

AIM OF STUDY

To investigate the therapeutic effect of idiopathic pulmonary fibrosis (IPF) of GGD, a bleomycin-induced IPF murine model was used in this study.

MATERIALS AND METHODS

Mice were induced by bleomycin instillation and GGD was orally administered. Changes on mice weight were recorded during the experiment. Lung weight was recorded on days 14 and 28, and pulmonary index was calculated accordingly. Pathological evaluation, including fibrosis analysis of lung tissue, was assessed by H&E and Masson staining. The expression of PD-1, p-STAT3 and IL-17A were detected by immunohistochemistry (IHC). The expression of p-STAT3 in lung tissues of mice were detected by Western blot. The level of IL-17A in lung tissue were detected by ELISA. The expression of PD-1 in CD4+ T cells in peripheral blood of mice was detected by flow cytometry. The levels of hydroxyproline and TGF-β1 in lung tissue were detected by ELISA. The expression of E-cadherin, vimentin and α-SMA in lung tissues of mice were detected by qRT-PCR and Western blot.

RESULTS

GGD can increase body weight and reduce pulmonary index in mice with pulmonary fibrosis. As such, GGD can significantly improve the inflammatory and alleviate IPF in the lung tissue of mice. GGD treatment was capable of reducing the content of PD-1 in lung tissue as well as the expression of PD-1 in CD4+ T cells in peripheral blood. Likewise, GGD was able to reduce the content of p-STAT3, IL-17A and TGF-β1. In addition, GGD stimulation could inhibit epithelial-mesenchymal transformation (EMT) by increasing the expression of E-cadherin and reducing vimentin and α-SMA, thus reducing extracellular matrix (ECM) deposition.

CONCLUSION

Our results indicate that GGD positively affects IPF by regulating PD-1/TGF-β1/IL-17A pathway.

Evaluation of the effect of filtered ultrafine particulate matter on bleomycin-induced lung fibrosis in a rat model using computed tomography, histopathologic analysis, and RNA sequencing

We aimed to investigate the effect of chronic particulate matter (PM) exposure on bleomycin-induced lung fibrosis in a rat model using chest CT, histopathologic evaluation, and RNA-sequencing. A bleomycin solution was intratracheally administrated to 20 male rats. For chronic PM exposure, after four weeks of bleomycin treatment to induce lung fibrosis, PM suspension (experimental group) or normal saline (control group) was intratracheally administrated for 10 weeks. Chest CT was carried out in all rats, and then both lungs were extracted for histopathologic evaluation. One lobe from three rats in each group underwent RNA sequencing, and one lobe from five rats in each group was evaluated by western blotting. Inflammation and fibrosis scores in both chest CT and pathologic analysis were significantly more aggravated in rats with chronic PM exposure than in the control group. Several genes associated with inflammation and immunity were also upregulated with chronic PM exposure. Our study revealed that chronic PM exposure in a bleomycin-induced lung fibrosis rat model aggravated pulmonary fibrosis and inflammation, proven by chest CT, pathologic analysis, and RNA sequencing.

Glutamine restores mitochondrial respiration in bleomycin-injured epithelial cells

Whether from known or unknown causes, loss of epithelial repair plays a central role in the pathogenesis of pulmonary fibrosis. Recently, diminished mitochondrial function has been implicated as a factor contributing to the loss of epithelial repair but the mechanisms mediating these changes have not been defined. Here, we investigated the factors contributing to mitochondrial respiratory dysfunction after bleomycin, a widely accepted agent for modeling pulmonary fibrosis in mice and in vitro systems. In agreement with previous reports, we found that mitochondrial respiration was decreased in lung epithelial cells exposed to bleomycin, but also observed that responses differed depending on the type of metabolic fuel available to cells. For example, we found that mitochondrial respiration was dramatically reduced when glucose served as the primary fuel. Moreover, this associated with a marked decrease in glucose uptake, expression of glucose uptake transport 1 and capacity to augment glycolysis to either glucose or oligomycin. Conversely, mitochondrial respiration was largely preserved if glutamine was present in culture medium. The addition of glutamine also led to increased intracellular metabolite levels, including multiple TCA cycle intermediates and the glycolytic intermediate lactate, as well as reduced DNA damage and cell death to bleomycin. Taken together, these findings indicate that glutamine, rather than glucose, supports mitochondrial respiration and metabolite production in injured lung epithelial cells, and suggest that this shift away from glucose utilization serves to protect the lung epithelium from injury.

Evaluation of microRNA expression in a sheep model for lung fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibroproliferative disorder that has one of the poorest prognoses amongst interstitial lung diseases. Recently, the finding of aberrant expression levels of miRNAs in IPF patients has drawn significant attention to the involvement of these molecules in the pathogenesis of this disease. Clarification of the differential expression of miRNAs in health and disease may identify novel therapeutic strategies that can be employed in the future to combat IPF. This study evaluates the miRNA expression profiles in a sheep model for lung fibrosis and compares them to the miRNA profiles of both IPF patients and the mouse bleomycin model for pulmonary fibrosis. Pathway enrichment analyses were performed on differentially expressed miRNAs to illustrate which biological mechanisms were associated with lung fibrosis.

RESULTS

We discovered 49 differentially expressed miRNAs in the sheep fibrosis model, in which 32 miRNAs were significantly down regulated, while 17 miRNAs were significantly upregulated due to bleomycin-induced lung injury. Moreover, the miRNA families miR-29, miR-26, miR-30, let-7, miR-21, miR-19, miR-17 and miR-199 were aberrantly expressed in both sheep and mouse models, with similar differential miRNAs expression observed in IPF cases. Importantly, 18 miRNAs were aberrantly expressed in both the sheep model and IPF patients, but not in mice.

CONCLUSION

Together with pathway enrichment analyses, these results show that the sheep model can potentially be used to characterize previously unrecognized biological pathways associated with lung fibrosis.

Intermittent hypoxia increases ROS/HIF-1α 'related oxidative stress and inflammation and worsens bleomycin-induced pulmonary fibrosis in adult male C57BL/6J mice

Obstructive sleep apnea (OSA) has been increasingly recognized as a risk factor for idiopathic pulmonary fibrosis (IPF). The intermittent hypoxia (IH) and re-oxygenation of OSA contribute to poor outcomes of IPF, however, the potential mechanism remains unknown. Here, C57BL/6J mice were administered intratracheal injection of Bleomycin (BLM) or saline and then exposed to IH (alternating cycles of FiO2 21% for 60S and FiO2 10% for 30 s, 40 cycles/hour, 8 h/day) to mimic OSA or intermittent air (IA) for 4 days, 8 days or 21 days. This study found that pulmonary fibrosis in BLM + IH treated mice was more severe than that in BLM + IA group at day 8 and 21, but not observed at day 4. Besides, the expression of reactive oxygen species (ROS) and hypoxia inducible factor-1α (HIF-1α),which are related to hypoxia reduced oxidative stress and inflammation, were higher in BLM + IH treated mice than BLM + IA mice, and IH increased these indexes in BLM treated mice from day 4 to day 21. Interestingly, a positive linear correlation between the HIF-1α expression and hydroxyproline (HYP) content was observed. We further found some inflammatory cells in bronchoalveolar lavage fluid were increased significantly from day 4 to 21, and there was a positive correlation between inflammation and ROS expression. Our results demonstrated that IH aggravated BLM-induced pulmonary fibrosis, and ROS/HIF-1α related oxidative stress and inflammation involved. The increase of ROS/HIF-1α related oxidative stress and inflammation may be a potential mechanism of moderate-to-severe OSA in potentiating pulmonary fibrosis of IPF, which warrants further study.

IL-35 subunit EBI3 alleviates bleomycin-induced pulmonary fibrosis via suppressing DNA enrichment of STAT3

BACKGROUND

IL-35 subunit EBI3 is up-regulated in pulmonary fibrosis tissues. In this study, we investigated the pathological role of EBI3 in pulmonary fibrosis and dissected the underlying molecular mechanism.

METHODS

Bleomycin-induced pulmonary fibrosis mouse model was established, and samples were performed gene expression analyses through RNAseq, qRT-PCR and Western blot. Wild type and EBI3 knockout mice were exposed to bleomycin to investigate the pathological role of IL-35, via lung function and gene expression analyses. Primary lung epithelial cells were used to dissect the regulatory mechanism of EBI3 on STAT1/STAT4 and STAT3.

RESULTS

IL-35 was elevated in both human and mouse with pulmonary fibrosis. EBI3 knockdown aggravated the symptoms of pulmonary fibrosis in mice. EBI3 deficiency enhanced the expressions of fibrotic and extracellular matrix-associated genes. Mechanistically, IL-35 activated STAT1 and STAT4, which in turn suppressed DNA enrichment of STAT3 and inhibited the fibrosis process.

CONCLUSION

IL-35 might be one of the potential therapeutic targets for bleomycin-induced pulmonary fibrosis.

Computed tomography-based radiomics decodes prognostic and molecular differences in interstitial lung disease related to systemic sclerosis

Background

Radiomic features calculated from routine medical images show great potential for personalised medicine in cancer. Patients with systemic sclerosis (SSc), a rare, multiorgan autoimmune disorder, have a similarly poor prognosis due to interstitial lung disease (ILD). Here, our objectives were to explore computed tomography (CT)-based high-dimensional image analysis (“radiomics”) for disease characterisation, risk stratification and relaying information on lung pathophysiology in SSc-ILD.

Methods

We investigated two independent, prospectively followed SSc-ILD cohorts (Zurich, derivation cohort, n=90; Oslo, validation cohort, n=66). For every subject, we defined 1355 robust radiomic features from standard-of-care CT images. We performed unsupervised clustering to identify and characterise imaging-based patient clusters. A clinically applicable prognostic quantitative radiomic risk score (qRISSc) for progression-free survival (PFS) was derived from radiomic profiles using supervised analysis. The biological basis of qRISSc was assessed in a cross-species approach by correlation with lung proteomic, histological and gene expression data derived from mice with bleomycin-induced lung fibrosis.

Results

Radiomic profiling identified two clinically and prognostically distinct SSc-ILD patient clusters. To evaluate the clinical applicability, we derived and externally validated a binary, quantitative radiomic risk score (qRISSc) composed of 26 features that accurately predicted PFS and significantly improved upon clinical risk stratification parameters in multivariable Cox regression analyses in the pooled cohorts. A high qRISSc score, which identifies patients at risk for progression, was reverse translatable from human to experimental ILD and correlated with fibrotic pathway activation.

Conclusions

Radiomics-based risk stratification using routine CT images provides complementary phenotypic, clinical and prognostic information significantly impacting clinical decision making in SSc-ILD.

CT-based radiomics decodes phenotypic, prognostic and molecular differences in SSc-ILD, and predicts progression-free survival with a significant impact on future clinical decision making in SSc-ILDhttps://bit.ly/3zPaMOn

Anlotinib Inhibits PFKFB3-Driven Glycolysis in Myofibroblasts to Reverse Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease in which the normal alveolar network is gradually replaced by fibrotic scars. Current evidence suggests that metabolic alterations correlate with myofibroblast activation in IPF. Anlotinib has been proposed to have antifibrotic effects, but the efficacy and mechanisms of anlotinib against lung fibrosis have not been systematically evaluated. The antifibrotic effects of anlotinib were evaluated in bleomycin-induced mouse models and transforming growth factor-beta 1 (TGF-β1)-stimulated lung fibroblasts. We measured lactate levels, 2-NBDG glucose uptake and the extracellular acidification rate (ECAR) to assess glycolysis in fibroblasts. RNA-protein coimmunoprecipitation (RIP) and polysome analyses were performed to investigate novel mechanisms of glycolytic reprogramming in pulmonary fibrosis. We found that anlotinib diminished myofibroblast activation and inhibited the augmentation of glycolysis. Moreover, we show that PCBP3 posttranscriptionally increases PFKFB3 expression by promoting its translation during myofibroblast activation, thus promoting glycolysis in myofibroblasts. Regarding mechanism, anlotinib exerts potent antifibrotic effects by downregulating PCBP3, reducing PFKFB3 translation and inhibiting glycolysis in myofibroblasts. Furthermore, we observed that anlotinib had preventative and therapeutic antifibrotic effects on bleomycin-induced pulmonary fibrosis. Therefore, we identify PCBP3 as a protein involved in the regulation of glycolysis reprogramming and lung fibrogenesis and propose it as a therapeutic target for pulmonary fibrosis. Our data suggest that anlotinib has antifibrotic effects on the lungs, and we provide a novel mechanism for this effect. Anlotinib may constitute a novel and potent candidate for the treatment of pulmonary fibrosis.

Iron oxide nanoparticles augment the intercellular mitochondrial transfer-mediated therapy

The transfer of mitochondria between cells has recently been revealed as a spontaneous way to protect the injured cells. However, the utilization of this natural transfer process for disease treatment is so far limited by its unsatisfactory transfer efficiency and selectivity. Here, we demonstrate that iron oxide nanoparticles (IONPs) can augment the intercellular mitochondrial transfer from human mesenchymal stem cells (hMSCs) selectively to diseased cells, owing to the enhanced formation of connexin 43–containing gap junctional channels triggered by ionized IONPs. In a mouse model of pulmonary fibrosis, the IONP-engineered hMSCs achieve a remarkable mitigation of fibrotic progression because of the promoted intercellular mitochondrial transfer, with no serious safety issues identified. The present study reports a potential method of using IONPs to enable hMSCs for efficient and safe transfer of mitochondria to diseased cells to restore mitochondrial bioenergetics.

Systems biology analysis of lung fibrosis-related genes in the bleomycin mouse model

Tissue fibrosis is a major driver of pathology in aging and is involved in numerous age-related diseases. The lungs are particularly susceptible to fibrotic pathology which is currently difficult to treat. The mouse bleomycin-induced fibrosis model was developed to investigate lung fibrosis and widely used over the years. However, a systematic analysis of the accumulated results has not been performed. We undertook a comprehensive data mining and subsequent manual curation, resulting in a collection of 213 genes (available at the TiRe database, www.tiredb.org ), which when manipulated had a clear impact on bleomycin-induced lung fibrosis. Our meta-analysis highlights the age component in pulmonary fibrosis and strong links of related genes with longevity. The results support the validity of the bleomycin model to human pathology and suggest the importance of a multi-target therapeutic strategy for pulmonary fibrosis treatment.

Intracellular hydroxyproline imprinting following resolution of bleomycin-induced pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with few treatment options. The poor success in developing anti-IPF strategies have impelled researchers to reconsider the importance of choice for animal model and assessment methodologies. Currently, it is still not settled whether the bleomycin-induced lung fibrosis mouse model finally returns to resolution.This study aimed to follow the dynamic fibrotic features of BLM (Bleomycin)-treated mouse lungs with extended durations through a combination of the latest technologies (micro-CT imaging and histological detection of degraded collagens) with traditional methods. In addition, we also applied immunohistochemistry to explore the distribution of all hydroxyproline-containing molecules.As determined by classical biochemical method, total lung hydroxyproline contents reached peak at 4-week after bleomycin injury and maintained a steady high level thereafter until the end of the experiments (16-week). This result seemed to partially contradict with the changes of other fibrosis evaluation parameters, which indicated a gradual degradation of collagens and a recovery of lung aeration post the fibrosis peak. This inconsistency was well reconciled by our data from immunostaining against hydroxyproline and a fluorescent peptide staining against degraded collagen, together showing large amounts of hydroxyproline-rich degraded collagen fragments detained and enriched within the intracellular regions at 10- or 16-week, rather than at 4-week post the BLM-treatment. Hence, our present data not only offer respiratory researchers a new perspective towards the resolution nature of mouse lung fibrosis, but also remind them to be cautious while using hydroxyproline content assay to evaluate the severity of fibrosis.

Collagen-derived dipeptide Pro-Hyp administration accelerates muscle regenerative healing accompanied by less scarring after wounding on the abdominal wall in mice

Collagens act as cellular scaffolds in extracellular matrixes, and their breakdown products may also have important biological functions. We hypothesize that collagen dipeptide Pro-Hyp induces favorable healing activities and examined the effects of Pro-Hyp administered via different routes on wound healing using our novel murine model, in which an advanced fibrosis-prone scar lesion was developed in the abdominal muscle wall under the skin. After excising a part of the abdominal wall, a free-drinking experiment was performed using solutions with casein (CS), high molecular weight collagen peptides (HP), and low molecular weight collagen peptides including Pro-Hyp and Hyp-Gly (LP), in addition to water (HO). On day 21 of the study, when compared to the HO and CS groups, muscle regeneration in the LP group was significantly advanced in the granulation tissue, which was associated with a decrease in fibrosis. To clarify the effects of Pro-Hyp, daily intraperitoneal administration of pure Pro-Hyp was performed. Pro-Hyp administration induced many myogenically differentiated cells, including myogenin-positive myoblasts and myoglobin-positive myocytes, to migrate in the granulation tissue, while scar tissue decreased. These results indicated that Pro-Hyp administration accelerates muscle regenerative healing accompanied by less scarring after wounding on the abdominal wall.

Bleomycin-Induced Lung Injury Increases Resistance to Influenza Virus Infection in a Type I Interferon-Dependent Manner

Acute lung injury (ALI) results in acute respiratory disease that causes fatal respiratory diseases; however, little is known about the incidence of influenza infection in ALI. Using a ALI-mouse model, we investigated the pro-inflammatory cytokine response to ALI and influenza infection. Mice treated with bleomycin (BLM), which induces ALI, were more resistant to influenza virus infection and exhibited higher levels of type I interferon (IFN-I) transcription during the early infection period than that in PBS-treated control mice. BLM-treated mice also exhibited a lower viral burden, reduced pro-inflammatory cytokine production, and neutrophil levels. In contrast, BLM-treated IFN-I receptor 1 (IFNAR1)-knockout mice failed to show this attenuated phenotype, indicating that IFN-I is key to the antiviral response in ALI-induced mice. The STING/TBK1/IRF3 pathway was found to be involved in IFN-I production and the establishment of an antiviral environment in the lung. The depletion of plasmacytoid dendritic cells (pDCs) reduced the effect of BLM treatment against influenza virus infection, suggesting that pDCs are the major source of IFN-I and are crucial for defense against viral infection in BLM-induced lung injury. Overall, this study showed that BLM-mediated ALI in mice induced the release of double-stranded DNA, which in turn potentiated IFN-I-dependent pulmonary viral resistance by activating the STING/TBK1/IRF3 pathway in association with pDCs.

Effectivity of mesenchymal stem cells for bleomycin-induced pulmonary fibrosis: a systematic review and implication for clinical application

Pulmonary fibrosis (PF) is a chronic, progressive, fibrotic interstitial disease of the lung with poor prognosis and without effective treatment currently. Data from previous coronavirus infections, such as the Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome, as well as current clinical evidence from the Coronavirus disease 2019 (COVID-19), support that SARS-CoV-2 infection may lead to PF, seriously impacting patient prognosis and quality of life. Therefore, effective prevention and treatment of PF will improve patient prognosis and reduce the overall social and economic burdens. Stem cells, especially mesenchymal stem cells (MSCs) have many great advantages, including migration to damaged lung tissue and secretion of various paracrine factors, thereby regulating the permeability of endothelial and epithelial cells, reducing inflammatory response, promoting tissue repair and inhibiting bacterial growth. Clinical trials of MSCs for the treatment of acute lung injury, PF and severe and critically ill COVID-19 are ongoing. The purpose of this study is to systematically review preclinical studies, explored the effectiveness of MSCs in the treatment of bleomycin (BLM)-induced pulmonary fibrosis and analyze the potential mechanism, combined with clinical trials of current MSCs for idiopathic pulmonary fibrosis (IPF) and COVID-19, so as to provide support for clinical research and transformation of MSCs. Searching PubMed and Embase (- 2021.4) identified a total of 36 preclinical studies of MSCs as treatment of BLM-induced acute lung injury and PF in rodent models. Most of the studies showed the MSCs treatment to reduce BLM-induced lung tissue inflammatory response, inflammatory cell infiltration, inflammatory cytokine expression, extracellular matrix production and collagen deposition, and to improve Ashcroft score. The results of present studies indicate that MSCs may serve as a potential therapeutic modality for the treatment of PF, including viral-induced PF and IPF.

Time course of histopathological changes after bleomycin sclerotherapy in rabbit gallbladders as a model for simple hepatic cysts

Bleomycin sclerotherapy is used in the treatment of cystic lesions; however, the histopathological changes are undefined. Present animal models of cystic diseases are not adequate for the study of sclerotherapy of hepatic cysts, primarily because the established cysts in these models are too small in size. The aim of the present study was to establish a new animal model of simple hepatic cysts, and assess the histopathological changes after bleomycin sclerotherapy. Rabbit gallbladder, with ligaturing of the cholecystic duct whilst preserving cholecystic vessels, was used as a model for simple hepatic cysts. Bleomycin (2 mg dissolved in 1 ml saline) was injected into the aspirated gallbladder, gallbladder tissue was harvested (after 1, 7, 14, 28, 42, 56 and 84 days) and histopathological changes were evaluated (n=4 per group). Additionally, control rabbit gallbladders were injected with 1 ml saline and sampled after 14 days (n=4). Histopathological changes were evaluated using hematoxylin-eosin and Masson's trichrome staining, and immunohistochemistry for CD20-, CD43- and CD68-positive cells was performed. The integrated optical density (IOD) of immunohistochemical staining and average positive stained area percentage (APSAP) of collagen were quantitatively analyzed. The results revealed gallbladders in the control group had regular epithelial cells with no visible inflammation or fibrosis. In the experimental group, epithelial cells were swollen and necrotic on the first day, and were replaced gradually by single-layer flat cells from day 56. Inflammatory infiltration was found in the submucosa, and the IOD of T cells, B cells and macrophages were highest on day 1, and these parameters declined gradually, eventually disappearing. The APSAP of collagen was highest on day 7, and gradually declined thereafter. The results suggest that histopathological changes after bleomycin sclerotherapy of a simple hepatic cyst model were characterized by sequential epithelial destruction, inflammatory cell infiltration, collagen proliferation and epithelial partial regeneration.

Cellular Senescence in Idiopathic Pulmonary Fibrosis

Cellular senescence (CS) is increasingly implicated in the etiology of age-related diseases. While CS can facilitate physiological processes such as tissue repair and wound healing, senescent cells also contribute to pathophysiological processes involving macromolecular damage and metabolic dysregulation that characterize multiple morbid and prevalent diseases, including Alzheimer's disease, osteoarthritis, atherosclerotic vascular disease, diabetes mellitus, and idiopathic pulmonary fibrosis (IPF). Preclinical studies targeting senescent cells and the senescence-associated secretory phenotype (SASP) with "senotherapeutics" have demonstrated improvement in age-related morbidity associated with these disease states. Despite promising results from these preclinical trials, few human clinical trials have been conducted. A first-in-human, open-label, pilot study of the senolytic combination of dasatinib and quercetin (DQ) in patients with IPF showed improved physical function and mobility. In this review, we will discuss our current understanding of cellular senescence, its role in age-associated diseases, with a specific focus on IPF, and potential for senotherapeutics in the treatment of fibrotic lung diseases.

Animal and Human Models of Tissue Repair and Fibrosis: An Introduction

Reductionist cell culture systems are not only convenient but essential to understand molecular mechanisms of myofibroblast activation and action in carefully controlled conditions. However, tissue myofibroblasts do not act in isolation and the complexity of tissue repair and fibrosis in humans cannot be captured even by the most elaborate culture models. Over the past five decades, numerous animal models have been developed to study different aspects of myofibroblast biology and interactions with other cells and extracellular matrix. The underlying principles can be broadly classified into: (1) organ injury by trauma such as prototypical full thickness skin wounds or burns; (2) mechanical challenges, such as pressure overload of the heart by ligature of the aorta or the pulmonary vein; (3) toxic injury, such as administration of bleomycin to lungs and carbon tetrachloride to the liver; (4) organ infection with viruses, bacteria, and parasites, such as nematode infections of liver; (5) cytokine and inflammatory models, including local delivery or viral overexpression of active transforming growth factor beta; (6) "lifestyle" and metabolic models such as high-fat diet; and (7) various genetic models. We will briefly summarize the most widely used mouse models used to study myofibroblasts in tissue repair and fibrosis as well as genetic tools for manipulating myofibroblast repair functions in vivo.

Fedratinib Attenuates Bleomycin-Induced Pulmonary Fibrosis via the JAK2/STAT3 and TGF-β1 Signaling Pathway

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease with multiple causes, characterized by excessive myofibrocyte aggregation and extracellular matrix deposition. Related studies have shown that transforming growth factor-β1 (TGF-β1) is a key cytokine causing fibrosis, promoting abnormal epithelial-mesenchymal communication and fibroblast-to-myofibroblast transition. Fedratinib (Fed) is a marketed drug for the treatment of primary and secondary myelofibrosis, targeting selective JAK2 tyrosine kinase inhibitors. However, its role in pulmonary fibrosis remains unclear. In this study, we investigated the potential effects and mechanisms of Fed on pulmonary fibrosis in vitro and in vivo. In vitro studies have shown that Fed attenuates TGF-β1- and IL-6-induced myofibroblast activation and inflammatory response by regulating the JAK2/STAT3 signaling pathway. In vivo studies have shown that Fed can reduce bleomycin-induced inflammation and collagen deposition and improve lung function. In conclusion, Fed inhibited inflammation and fibrosis processes induced by TGF-β1 and IL-6 by targeting the JAK2 receptor.

Danggui Buxue Tang Ameliorates Bleomycin-Induced Pulmonary Fibrosis by Suppressing the TLR4/NLRP3 Signaling Pathway in Rats

Objective

To investigate the effects of Danggui Buxue Tang (DBT) on rats with pulmonary fibrosis (PF) and the underlying mechanism.

Methods

Sixty specific pathogen-free (SPF) male Sprague-Dawley (SD) rats were randomly divided into 4 groups: control, PF, prednisone treatment, and DBT treatment. Intratracheal instillation of bleomycin (BLM) was performed to establish a PF rat model. DBT was administered to PF rats concurrently for 2 weeks. Lung samples were then collected for HE and Masson staining after pulmonary function testing, and semiquantitative analysis for the degree of alveolitis and fibrosis was performed using the Szapiel and Ashcroft score systems. Myeloperoxidase (MPO) activity, hydroxyproline (HYP), hyaluronic acid (HA), and inflammatory cytokine content were measured. Western blotting was performed to detect fibrotic marker and TLR4/NLRP3 signaling pathway changes.

Results

Oral administration of DBT attenuated weight loss, survival rate, and pulmonary index. Lung histopathologic lesions were also reduced. DBT inhibited PF by decreasing the secretion of inflammatory cytokines and collagen deposition. Specifically, DBT reduced tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), IL-6, HYP, alpha-smooth muscle actin (α-SMA), collagen I, and collagen III levels. Corollary experiments identified a potential mechanism involving suppression of TLR4/MyD88/NF-κB signaling pathway activation and the NLRP3/ASC/caspase-1 axis, the downstream regulatory pathway.

Conclusion

DBT exhibited a potent effect on BLM-induced PF rats by inhibiting the TLR4/NLRP3 signaling pathway. Thus, DBT alleviates pulmonary inflammation to inhibit fibrotic pathology and should be considered as a candidate for the clinical treatment of PF.

Pleural mesothelial cell migration into lung parenchyma by calpain contributes to idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is defined as a specific form of chronic, progressive fibrosing interstitial pneumonia. It is unknown why fibrosis in IPF distributes in the peripheral or named sub-pleural area. Migration of pleural mesothelial cells (PMC) should contribute to sub-pleural fibrosis. Calpain is known to be involved in cell migration, but the role of calpain in PMC migration has not been investigated. In this study, we found that PMCs migrated into lung parenchyma in patients with IPF. Then using Wt1^{tm1(EGFP/Cre)Wtp} /J knock-in mice, we observed PMC migration into lung parenchyma in bleomycin-induced pleural fibrosis models, and calpain inhibitor attenuated pulmonary fibrosis with prevention of PMC migration. In vitro studies revealed that bleomycin and transforming growth factor-β1 increased calpain activity in PMCs, and activated calpain-mediated focal adhesion (FA) turnover as well as cell migration, cell proliferation, and collagen-I synthesis. Furthermore, we determined that calpain cleaved FA kinase in both C-terminal and N-terminal regions, which mediated FA turnover. Lastly, the data revealed that activated calpain was also involved in phosphorylation of cofilin-1, and p-cofilin-1 induced PMC migration. Taken together, this study provides evidence that calpain mediates PMC migration into lung parenchyma to promote sub-pleural fibrosis in IPF.

The predicting roles of carcinoembryonic antigen and its underlying mechanism in the progression of coronavirus disease 2019

BACKGROUND

The coronavirus disease 2019 (COVID-19) has induced a worldwide epidemiological event with a high infectivity and mortality. However, the predicting biomarkers and their potential mechanism in the progression of COVID-19 are not well known.

OBJECTIVE

The aim of this study is to identify the candidate predictors of COVID-19 and investigate their underlying mechanism.

METHODS

The retrospective study was conducted to identify the potential laboratory indicators with prognostic values of COVID-19 disease. Then, the prognostic nomogram was constructed to predict the overall survival of COVID-19 patients. Additionally, the scRNA-seq data of BALF and PBMCs from COVID-19 patients were downloaded to investigate the underlying mechanism of the most important prognostic indicators in lungs and peripherals, respectively.

RESULTS

In total, 304 hospitalized adult COVID-19 patients in Wuhan Jinyintan Hospital were included in the retrospective study. CEA was the only laboratory indicator with significant difference in the univariate (P < 0.001) and multivariate analysis (P = 0.020). The scRNA-seq data of BALF and PBMCs from COVID-19 patients were downloaded to investigate the underlying mechanism of CEA in lungs and peripherals, respectively. The results revealed the potential roles of CEA were significantly distributed in type II pneumocytes of BALF and developing neutrophils of PBMCs, participating in the progression of COVID-19 by regulating the cell-cell communication.

CONCLUSION

This study identifies the prognostic roles of CEA in COVID-19 patients and implies the potential roles of CEACAM8-CEACAM6 in the progression of COVID-19 by regulating the cell-cell communication of developing neutrophils and type II pneumocyte.

Kindlin-2 Acts as a Key Mediator of Lung Fibroblast Activation and Pulmonary Fibrosis Progression

Pulmonary fibrosis is a progressive and fatal lung disease characterized by activation of lung fibroblasts and excessive deposition of collagen matrix. We show here that the concentrations of kindlin-2 and its binding partner PYCR1, a key enzyme for proline synthesis, are significantly increased in the lung tissues of human patients with pulmonary fibrosis. Treatment of human lung fibroblasts with TGF-β1 markedly increased the expression of kindlin-2 and PYCR1, resulting in increased kindlin-2 mitochondrial translocation, formation of the kindlin-2-PYCR1 complex, and proline synthesis. The concentrations of the kindlin-2-PYCR1 complex and proline synthesis were markedly reduced in response to pirfenidone or nintedanib, two clinically approved therapeutic drugs for pulmonary fibrosis. Furthermore, depletion of kindlin-2 alone was sufficient to suppress TGF-β1-induced increases of PYCR1 expression, proline synthesis, and fibroblast activation. Finally, using a bleomycin mouse model of pulmonary fibrosis, we show that ablation of kindlin-2 effectively reduced the concentrations of PYCR1, proline, and collagen matrix and alleviate the progression of pulmonary fibrosis in vivo. Our results suggest that kindlin-2 is a key promoter of lung fibroblast activation, collagen matrix synthesis, and pulmonary fibrosis, underscoring the therapeutic potential of targeting the kindlin-2 signaling pathway for control of this deadly lung disease.

PPARγ mediates the anti-pulmonary fibrosis effect of icaritin

BACKGROUND

Pulmonary fibrosis is a fatal lung disease with limited treatment options. Icaritin is the active ingredient derived from the traditional Chinese medical plant Epimedium and possesses many biomedical activities. This study aimed to investigate the effects and molecular mechanisms of icaritin on bleomycin-induced pulmonary fibrosis in mice.

METHODS

To assess its preventative effects, bleomycin treated mice received 0, 0.04, 0.2, and 1 mg/kg of icaritin from day 1 onwards. To assess its therapeutic effects, bleomycin treated mice received 0 and 1 mg/kg of icaritin from day 15 onwards. Mice were sacrificed on day 21 and lung tissues were collected, stained with HE, Masson and immunohistochemistry. Q-PCR was used to measure Collagen I and Collagen III expression, western blotting was used to quantify α-SMA, Collagen I expression. Hydroxyproline content was measured using a biochemical method. NIH3T3 and HLF-1 cells were treated with TGF-β1with or without icaritin, and α-SMA, Collagen I were tested. PPARγ antagonist GW9662 and PPARγ-targeted siRNA were used to investigate the mechanism of icaritin in inhibiting myofibroblast differentiation.

RESULTS

Both preventative and therapeutic administration of icaritin improved the histopathological changes, decreased Collagen and α-SMA, lowered hydroxyproline content in bleomycin-treated lung tissues. Icaritin decreased α-SMA and Collagen I expression in TGF-β1-stimulated NIH3T3 and HLF-1 cells. However, its effect in reducing α-SMA and Collagen I expression was suppressed when expression or activity of PPARγ was inhibited.

CONCLUSIONS

Icaritin has therapeutic potential against pulmonary fibrosis via the inhibition of myofibroblast differentiation, which may be mediated by PPARγ.

Chelerythrine Ameliorates Pulmonary Fibrosis via Activating the Nrf2/ARE Signaling Pathway

Chelerythrine (CHE) is a natural benzophenanthridine alkaloid, which has shown its anti-fibrosis activity in kidney and liver, while the impact of CHE in pulmonary fibrosis is still unclear. This study is developed to explore the impact and mechanism of CHE in pulmonary fibrosis. Pulmonary fibrosis mouse models were established through intratracheal injection of bleomycin (BLM), after which the mice were intraperitoneally injected with CHE (0.375 or 0.75 mg/kg/d) every other day. The mice were sacrificed at the 28th day to collect blood serum, bronchoalveolar lavage fluid (BALF), and pulmonary tissues. Then, the severity of pulmonary fibrosis and the expression of nuclear factor erythroid 2 [NF-E2]-related factor 2 (Nrf2) in the pulmonary tissues were detected. Western blot analysis quantified the expressions of fibronectin and alpha-smooth muscle actin (α-SMA). The levels of 4-hydroxynonenal (4-HNE), glutathione (GSH), superoxide dismutase (SOD), TGF-β and hydroxyproline (HP) in the BALF, and pulmonary tissues were measured. The expression levels of Nrf2 and its downstream genes, hemeoxygenase-1 (HO-1) and NAD (P) H: quinone oxidoreductase (NQO1) were examined. CHE at the concentration of 0.375 or 0.75 mg/kg/d could attenuate pulmonary fibrosis. CHE injection reduced the expression levels of fibronectin, α-SMA, and TGF-β, upregulated the levels of SOD and GSH and decreased the levels of 4-HNE and HP. Also, CHE increased the expressions of Nrf2, HO-1, and NQO1. Treatment of Nrf2/antioxidant response element (ARE) inhibitor could block the Nrf2/ARE signaling pathway, thus perturbing the inhibition of CHE on BLM-stimulated pulmonary fibrosis in mice. CHE alleviates BLM-induced pulmonary fibrosis in mice through activating the Nrf2/ARE pathway to increase the activity of antioxidant enzymes.

Cymbopogon winterianus Essential Oil Attenuates Bleomycin-Induced Pulmonary Fibrosis in a Murine Model

The essential oil of Cymbopogon winterianus (EOCW) is a natural product with antioxidant, anti-inflammatory, and antifibrotic properties. We studied the effect of EOCW in the progression of histological changes of pulmonary fibrosis (PF) in a rodent model. The oil was obtained by hydrodistillation and characterized using gas chromatography–mass spectrometry. Intratracheal instillation of bleomycin was performed in 30 rats to induce PF, while Sham animals were subjected to instillation of saline solution. The treatment was performed using daily oral administration of distilled water, EOCW at 50, 100, and 200 mg/kg, and deflazacort (DFC). After 28 days, hemogram and bronchoalveolar lavage fluid (BALF), tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were assayed. Histological grading of PF, immunohistochemical expression of α-smooth muscle actin (α-SMA), and transforming growth factor-β (TGF-β) were also analyzed. The EOCW major compounds were found to be citronellal, geraniol, and citronellol. EOCW significantly reduced inflammation in BALF, reduced MDA levels, and increased SOD activity. EOCW attenuated histological grading of PF and reduced immunohistochemical expression of α-SMA and TGF-β in a dose-dependent way, likely due to the reduction of oxidative stress, inflammation, and TGF-β-induced myofibroblast differentiation.

Counter Regulation of Spic by NF-κB and STAT Signaling Controls Inflammation and Iron Metabolism in Macrophages

Activated macrophages must carefully calibrate their inflammatory responses to balance efficient pathogen control with inflammation-mediated tissue damage, but the molecular underpinnings of this "balancing act" remain unclear. Using genetically engineered mouse models and primary macrophage cultures, we show that Toll-like receptor (TLR) signaling induces the expression of the transcription factor Spic selectively in patrolling monocytes and tissue macrophages by a nuclear factor κB (NF-κB)-dependent mechanism. Functionally, Spic downregulates pro-inflammatory cytokines and promotes iron efflux by regulating ferroportin expression in activated macrophages. Notably, interferon-gamma blocks Spic expression in a STAT1-dependent manner. High levels of interferon-gamma are indicative of ongoing infection, and in its absence, activated macrophages appear to engage a "default" Spic-dependent anti-inflammatory pathway. We also provide evidence for the engagement of this pathway in sterile inflammation. Taken together, our findings uncover a pathway wherein counter-regulation of Spic by NF-κB and STATs attune inflammatory responses and iron metabolism in macrophages.

Deoxidized gulose moiety attenuates the pulmonary toxicity of 6'-deoxy-bleomycin Z without effect on its antitumor activity

Bleomycins (BLMs) are broad-spectrum antitumor drugs, but the dose-dependent lung toxicity has restricted their therapeutic applications. Many efforts have contributed to develop novel BLM analogues, but mainly focused on single functional domain owing to the structural complexity of BLM. Benefit from the engineered production of two novel analogues 6'-deoxy-BLM Z (6'-DO-BLM Z) and BLM Z, they together with clinical BLM-sulfate comprised a good model with varied sugar or C-terminal domain in any two of them, allowing us to study their structure-activity relationships pairwise. Our investigations suggested the biological activities of BLM or its analogues are mainly depended on the C-terminal amine, while the changed C-terminal amine endowed BLM Z with much higher pulmonary toxicity comparing to BLM-sulfate, whereas the deoxidized gulose unit with same C-terminal amine evidently attenuated the pulmonary toxicity of 6'-DO-BLM Z without effect on antitumor activity. Further mechanistic studies revealed that the alleviation of pulmonary toxicity in 6'-DO-BLM Z by a slight change in the sugar moiety could attribute to the decrease of ROS production and thereby reduce the subsequent caspase-1 activity and resulting inflammatory response. Therefore, the synergistic modifications on C-terminal amine and sugar moiety provide new insights to efficiently develop potential BLM candidate with good clinical performance.

Anti-Fibrosis Effects of Magnesium Lithospermate B in Experimental Pulmonary Fibrosis: By Inhibiting TGF-βRI/Smad Signaling

Pulmonary fibrosis is a severe and irreversible interstitial pulmonary disease with high mortality and few treatments. Magnesium lithospermate B (MLB) is a hydrosoluble component of Salvia miltiorrhiza and has been reported to have antifibrotic effects in other forms of tissue fibrosis. In this research, we studied the effects of MLB on pulmonary fibrosis and the underlying mechanisms. Our results indicated that MLB treatment (50 mg/kg) for seven days could attenuate bleomycin (BLM)-induced pulmonary fibrosis by reducing the alveolar structure disruption and collagen deposition in the C57 mouse model. MLB was also found to inhibit transforming growth factor-beta (TGF-β)-stimulated myofibroblastic transdifferentiation of human lung fibroblast cell line (MRC-5) cells and collagen production by human type II alveolar epithelial cell line (A549) cells, mainly by decreasing the expression of TGF-β receptor I (TGF-βRI) and regulating the TGF-β/Smad pathway. Further studies confirmed that the molecular mechanisms of MLB in BLM-induced pulmonary fibrosis mice were similar to those observed in vitro. In summary, our results demonstrated that MLB could alleviate experimental pulmonary fibrosis both in vivo and in vitro, suggesting that MLB has great potential for pulmonary fibrosis treatment.

Organoid Model in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive- fibrosing disease characterized by extensive deposition of extracellular matrix (ECM), scarring of the lung parenchyma. Despite increased awareness of IPF, etiology and physiological mechanism of IPF are unclear. Therefore, preclinical model will require relevant and recapitulative features of IPF. Recently, pluripotent stem cells (PSC)-based organoid studies are emerging as an alternative approach able to recapitulate tissue architecture with remarkable fidelity. Moreover, these biomimetic tissue models can be served to investigate the mechanisms of diverse disease progression. In this review, we will overview the current organoids technology for human disease modeling including lung organoids for IPF.

Elevated inflammatory responses and targeted therapeutic intervention in a preclinical mouse model of ataxia-telangiectasia lung disease

Ataxia-telangiectasia (A-T) is an autosomal recessive, multisystem disorder characterized by cerebellar degeneration, cancer predisposition, and immune system defects. A major cause of mortality in A-T patients is severe pulmonary disease; however, the underlying causes of the lung complications are poorly understood, and there are currently no curative therapeutic interventions. In this study, we examined the lung phenotypes caused by ATM-deficient immune cells using a mouse model of A-T pulmonary disease. In response to acute lung injury, ATM-deficiency causes decreased survival, reduced blood oxygen saturation, elevated neutrophil recruitment, exaggerated and prolonged inflammatory responses and excessive lung injury compared to controls. We found that ATM null bone marrow adoptively transferred to WT recipients induces similar phenotypes that culminate in impaired lung function. Moreover, we demonstrated that activated ATM-deficient macrophages exhibit significantly elevated production of harmful reactive oxygen and nitrogen species and pro-inflammatory cytokines. These findings indicate that ATM-deficient immune cells play major roles in causing the lung pathologies in A-T. Based on these results, we examined the impact of inhibiting the aberrant inflammatory responses caused by ATM-deficiency with reparixin, a CXCR1/CXCR2 chemokine receptor antagonist. We demonstrated that reparixin treatment reduces neutrophil recruitment, edema and tissue damage in ATM mutant lungs. Thus, our findings indicate that targeted inhibition of CXCR1/CXCR2 attenuates pulmonary phenotypes caused by ATM-deficiency and suggest that this treatment approach represents a viable therapeutic strategy for A-T lung disease.

Histological and Physiological Studies of the Effect of Bone Marrow-Derived Mesenchymal Stem Cells on Bleomycin Induced Lung Fibrosis in Adult Albino Rats

BACKGROUND

Lung fibrosis is considered as an end stage for many lung diseases including lung inflammatory disease, autoimmune diseases and malignancy. There are limited therapeutic options with bad prognostic outcome. The aim of this study was to explore the effect of mesenchymal stem cells (MSCs) derived from bone marrow on Bleomycin (BLM) induced lung fibrosis in albino rats.

METHODS

30 adult female albino rats were distributed randomly into 4 groups; negative control group, Bleomycin induced lung fibrosis group, lung fibrosis treated with bone marrow-MSCs (BM-MSCs) and lung fibrosis treated with cell free media. Lung fibrosis was induced with a single dose of intratracheal instillation of BLM. BM-MSCs or cell free media were injected intravenously 28 days after induction and rats were sacrificed after another 28 days for assessment. Minute respiratory volume (MRV), forced vital capacity (FVC) and forced expiratory volume 1 (FEV1) were recorded using spirometer (Power lab data acquisition system). Histological assessment was performed by light microscopic examination of H&E, and Masson's trichrome stained sections and was further supported by morphometric studies. In addition, electron microscopic examination to assess ultra-structural changes was done. Confocal Laser microscopy and PCR were used as tools to ensure MSCs homing in the lung.

RESULTS

Induction of lung fibrosis was confirmed by histological examination, which revealed disorganized lung architecture, thickened inter-alveolar septa due excessive collagen deposition together with inflammatory cellular infiltration. Moreover, pneumocytes depicted variable degenerative changes. Reduction in MRV, FVC and FEV1 were recorded. BM-MSCs treatment showed marked structural improvement with minimal cellular infiltration and collagen deposition and hence restored lung architecture, together with lung functions.

CONCLUSION

MSCs are promising potential therapy for lung fibrosis that could restore the normal structure and function of BLM induced lung fibrosis.

Human ex vivo lung perfusion: a novel model to study human lung diseases

Experimental animal models to predict physiological responses to injury and stress in humans have inherent limitations. Therefore, the development of preclinical human models is of paramount importance. Ex vivo lung perfusion (EVLP) has typically been used to recondition donor lungs before transplantation. However, this technique has recently advanced into a model to emulate lung mechanics and physiology during injury. In the present study, we propose that the EVLP of diseased human lungs is a well-suited preclinical model for translational research on chronic lung diseases. Throughout this paper, we demonstrate this technique's feasibility in pulmonary arterial hypertension (PAH), idiopathic pulmonary fibrosis (IPF), emphysema, and non-disease donor lungs not suitable for transplantation. In this study, we aimed to perfuse the lungs for 6 h with the EVLP system. This facilitated a robust and continuous assessment of airway mechanics, pulmonary hemodynamics, gas exchange, and biochemical parameters. We then collected at different time points tissue biopsies of lung parenchyma to isolate RNA and DNA to identify each disease's unique gene expression. Thus, demonstrating that EVLP could successfully serve as a clinically relevant experimental model to derive essential insights into pulmonary pathophysiology and various human lung diseases.

Protective Role of the Nucleic Acid Sensor STING in Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common and severe type of interstitial lung disease for which current treatments display limited efficacy. IPF is largely driven by host-derived danger signals released upon recurrent local tissue damage. Here we explored the roles of self-DNA and stimulator of interferon genes (STING), a protein belonging to an intracellular DNA sensing pathway that leads to type I and/or type III interferon (IFN) production upon activation. Using a mouse model of IPF, we report that STING deficiency leads to exacerbated pulmonary fibrosis with increased collagen deposition in the lungs and excessive remodeling factors expression. We further show that STING-mediated protection does not rely on type I IFN signaling nor on IL-17A or TGF-β modulation but is associated with dysregulated neutrophils. Together, our data support an unprecedented immunoregulatory function of STING in lung fibrosis.

Diversity and Biology of Cancer-Associated Fibroblasts

Efforts to develop anti-cancer therapies have largely focused on targeting the epithelial compartment, despite the presence of non-neoplastic stromal components that substantially contribute to the progression of the tumor. Indeed, cancer cell survival, growth, migration, and even dormancy are influenced by the surrounding tumor microenvironment (TME). Within the TME, cancer-associated fibroblasts (CAFs) have been shown to play several roles in the development of a tumor. They secrete growth factors, inflammatory ligands, and extracellular matrix proteins that promote cancer cell proliferation, therapy resistance, and immune exclusion. However, recent work indicates that CAFs may also restrain tumor progression in some circumstances. In this review, we summarize the body of work on CAFs, with a particular focus on the most recent discoveries about fibroblast heterogeneity, plasticity, and functions. We also highlight the commonalities of fibroblasts present across different cancer types, and in normal and inflammatory states. Finally, we present the latest advances regarding therapeutic strategies targeting CAFs that are undergoing preclinical and clinical evaluation.

A novel tree shrew model of pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease without effective therapy. Animal models effectively reproducing IPF disease features are needed to study the underlying molecular mechanisms. Tree shrews are genetically, anatomically, and metabolically closer to humans than rodents or dogs; therefore, the tree shrew model presents a unique opportunity for translational research in lung fibrosis. Here we demonstrate that tree shrews have in vivo and in vitro fibrotic responses induced by bleomycin and pro-fibrotic mediators. Bleomycin exposure induced lung fibrosis evidenced by histological and biochemical fibrotic changes. In primary tree shrew lung fibroblasts, transforming growth factor beta-1 (TGF-β1) induced myofibroblast differentiation, increased extracellular matrix (ECM) protein production, and focal adhesion kinase (FAK) activation. Tree shrew lung fibroblasts showed enhanced migration and increased matrix invasion in response to platelet derived growth factor BB (PDGF-BB). Inhibition of FAK significantly attenuated pro-fibrotic responses in lung fibroblasts. The data demonstrate that tree shrews have in vivo and in vitro fibrotic responses similar to that observed in IPF. The data, for the first time, support that the tree shrew model of lung fibrosis is a new and promising experimental animal model for studying the pathophysiology and therapeutics of lung fibrosis.

Bleomycin: A novel osteogenesis inhibitor of dental follicle cells via a TGF-β1/SMAD7/RUNX2 pathway

BACKGROUND AND PURPOSE

Tooth eruption is a complicated process regulated by the dental follicles (DF). Our recent study discovered that tooth eruption was inhibited upon injection of bleomycin into DF. However, the mechanisms were unknown.

EXPERIMENTAL APPROACH

Human dental follicle cells (hDFCs) were treated by bleomycin or exogenous TGF-β1 or transfected by plasmids loading SMAD7 or shRNA targeting SMAD7, followed by osteogenesis induction assay and signalling analysis. Human fresh DF tissues and Wistar rats were used to further confirm bleomycin function.

KEY RESULTS

Bleomycin decreased expression of RUNX2 and osteogenic genes in hDFCs, reducing osteogenic capacity. TGF-β1 expression was up-regulated in bleomycin-treated hDFCs. The effects of exogenous TGF-β1 were similar to those of bleomycin in hDFCs. Additionally, compared to SMAD2/3, SMAD7 expression increased more in bleomycin- or TGF-β1-treated hDFCs. Overexpression of SMAD7 likewise significantly decreased RUNX2 expression and osteogenic capacity of hDFCs. Knockdown of SMAD7 markedly attenuated the inhibitory effects of bleomycin and TGF-β1 on osteogenic capacity and RUNX2 expression of hDFCs. Most importantly, changes in TGF-β1, SMAD7, and RUNX2 expressions were similar in the DF of rats and humans treated with bleomycin.

CONCLUSION AND IMPLICATIONS

SMAD7 was a negative regulator of osteogenic differentiation in DFCs through suppressing RUNX2 expression. Bleomycin or TGF-β1 inhibited osteogenic differentiation of DFCs via a TGF-β1/SMAD7/RUNX2 pathway. Our findings might be beneficial for enhancing the osteogenic activity of DFCs or inhibiting the eruption of undesirable teeth.