• Tuberculosis and Respiratory Diseases
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• v.85 no.4
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• pp.320-331
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• 2022

Coronavirus disease 2019 (COVID-19) has become a major health burden worldwide, with over 450 million confirmed cases and 6 million deaths. Although the acute phase of COVID-19 management has been established, there is still a long way to go to evaluate the long-term clinical course or manage complications due to the relatively short outbreak of the virus. Pulmonary fibrosis is one of the most common respiratory complications associated with COVID-19. Scarring throughout the lungs after viral or bacterial pulmonary infection have been commonly observed, but the prevalence of post-COVID-19 pulmonary fibrosis is rapidly increasing. However, there is limited information available about post-COVID-19 pulmonary fibrosis, and there is also a lack of consensus on what condition should be defined as post-COVID-19 pulmonary fibrosis. During a relatively short follow-up period of approximately 1 year, lesions considered related to pulmonary fibrosis often showed gradual improvement; therefore, it is questionable at what time point fibrosis should be evaluated. In this review, we investigated the epidemiology, risk factors, pathogenesis, and management of post-COVID-19 pulmonary fibrosis.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.2
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• pp.103-111
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• 2022

Idiopathic pulmonary fibrosis (IPF) is a progressive disease caused by some risk factors, including smoking, viral infection, toxic substances, and radiation, that decline lung function of fresh oxygen and blood delivery throughout the body. Patients with pulmonary fibrosis have suffered from breathing and cough and the average survival rate is only 3 years after diagnosis. Therefore, it is significant to diagnose IPF and start treatment in enough time. Usually, lung biopsy is available to diagnose localized pulmonary fibrotic sites directly. However, it is insufficient to visualize whole lung tissue, and also it has a risk of infection for patients. In the clinic, medical imaging systems can diagnose pulmonary fibrosis non-invasively without infection. In this review, we introduce current medical imaging systems used to diagnose pulmonary fibrosis, including CT, MRI, and nuclear medicine. Further, we introduce several molecular imaging probes targeting specific biomarkers which are expressed in pulmonary fibrosis. Through this paper, it is expected that it would be helpful to understand the latest knowledge and research trends on pulmonary fibrosis diagnostic imaging.

• Journal of Yeungnam Medical Science
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• v.37 no.4
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• pp.269-276
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• 2020

Fibrosis is characterized by excessive accumulation of extracellular matrix components. The fibrotic process ultimately leads to organ dysfunction and failure in chronic inflammatory and metabolic diseases such as pulmonary fibrosis, advanced kidney disease, and liver cirrhosis. Idiopathic pulmonary fibrosis (IPF) is a common form of progressive and chronic interstitial lung disease of unknown etiology. Pathophysiologically, the parenchyma of the lung alveoli, interstitium, and capillary endothelium becomes scarred and stiff, which makes breathing difficult because the lungs have to work harder to transfer oxygen and carbon dioxide between the alveolar space and bloodstream. The transforming growth factor beta (TGF-β) signaling pathway plays an important role in the pathogenesis of pulmonary fibrosis and scarring of the lung tissue. Recent clinical trials focused on the development of pharmacological agents that either directly or indirectly target kinases for the treatment of IPF. Therefore, to develop therapeutic targets for pulmonary fibrosis, it is essential to understand the key factors involved in the pathogenesis of pulmonary fibrosis and the underlying signaling pathway. The objective of this review is to discuss the role of kinase signaling cascades in the regulation of either TGF-β-dependent or other signaling pathways, including Rho-associated coiled-coil kinase, c-jun N-terminal kinase, extracellular signal-regulated kinase 5, and p90 ribosomal S6 kinase pathways, and potential therapeutic targets in IPF.

• Toxicological Research
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• v.26 no.2
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• pp.137-147
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• 2010

Pulmonary fibrosis is a common consequence of many lung diseases and a leading cause of morbidity and mortality. The molecular mechanisms underlying the development of pulmonary fibrosis remain poorly understood. One model used successfully to study pulmonary fibrosis over the past few decades is the bleomycin-induced pulmonary fibrosis model. We aimed to identify the genes associated with fibrogenesis using an Affymetrix GeneChip system in a bleomycin-induced rat model for pulmonary fibrosis. To confirm fibrosis development, several analyses were performed, including cellular evaluations using bronchoalveolar lavage fluid, measurement of lactate dehydrogenase activity, and histopathological examinations. Common aspects of pulmonary fibrosis such as prolonged inflammation, immune cell infiltration, emergence of fibroblasts, and deposition of extracellular matrix and connective tissue elements were observed. Global gene expression analysis revealed significantly altered expression of genes ($\geq$ 1.5-fold, p < 0.05.) in a time-dependent manner during the development of pulmonary fibrosis. Our results are consistent with previous results of well-documented gene expression. Interestingly, the expression of triggering receptor expressed on myeloid cells 2 (Trem2), secreted phosphoprotein 1 (Spp1), and several proteases such as Tpsab1, Mcpt1, and Cma1 was considerably induced in the lung after bleomycin treatment, despite little evidence that they are involved in pulmonary fibrogenesis. These data will aid in our understanding of fibrogenic mechanisms and contribute to the identification of candidate biomarkers of fibrotic disease development.

• BMB Reports
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• v.57 no.3
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• pp.143-148
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• 2024

Pulmonary fibrosis is a serious lung disease that occurs predominantly in men. Genistein is an important natural soybean-derived phytoestrogen that affects various biological functions, such as cell migration and fibrosis. However, the antifibrotic effects of genistein on pulmonary fibrosis are largely unknown. The antifibrotic effects of genistein were evaluated using in vitro and in vivo models of lung fibrosis. Proteomic data were analyzed using nano-LC-ESI-MS/MS. Genistein significantly reduced transforming growth factor (TGF)-β1-induced expression of collagen type I and α-smooth muscle actin (SMA) in MRC-5 cells and primary fibroblasts from patients with idiopathic pulmonary fibrosis (IPF). Genistein also reduced TGF-β1-induced expression of p-Smad2/3 and p-p38 MAPK in fibroblast models. Comprehensive protein analysis confirmed that genistein exerted an anti-fibrotic effect by regulating various molecular mechanisms, such as unfolded protein response, epithelial mesenchymal transition (EMT), mammalian target of rapamycin complex 1 (mTORC1) signaling, cell death, and several metabolic pathways. Genistein was also found to decrease hydroxyproline levels in the lungs of BLM-treated mice. Genistein exerted an anti-fibrotic effect by preventing fibroblast activation, suggesting that genistein could be developed as a pharmacological agent for the prevention and treatment of pulmonary fibrosis.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.5
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• pp.401-411
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• 2015

Aldose reductase (AR) is known to play a crucial role in the mediation of diabetic and cardiovascular complications. Recently, several studies have demonstrated that allergen-induced airway remodeling and ovalbumin-induced asthma is mediated by AR. Epalrestat is an aldose reductase inhibitor that is currently available for the treatment of diabetic neuropathy. Whether AR is involved in pathogenesis of pulmonary fibrosis and whether epalrestat attenuates pulmonary fibrosis remains unknown. Pulmonary fibrosis was induced by intratracheal instillation of bleomycin (5 mg/kg) in rats. Primary pulmonary fibroblasts were cultured to investigate the proliferation by BrdU incorporation method and flow cytometry. The expression of AR, TGF-${\beta}_1$, ${\alpha}$-SMA and collagen I was analyzed by immunohistochemisty, real-time PCR or western blot. In vivo, epalrestat treatment significantly ameliorated the bleomycin-mediated histological fibrosis alterations and blocked collagen deposition concomitantly with reversing bleomycin-induced expression up-regulation of TGF-${\beta}_1$, AR, ${\alpha}$-SMA and collagen I (both mRNA and protein). In vitro, epalrestat remarkably attenuated proliferation of pulmonary fibroblasts and expression of ${\alpha}$-SMA and collagen I induced by TGF-${\beta}_1$, and this inhibitory effect of epalrestat was accompanied by inhibiting AR expression. Knockdown of AR gene expression reversed TGF-${\beta}_1$-induced proliferation of fibroblasts, up-regulation of ${\alpha}$-SMA and collagen I expression. These findings suggest that AR plays an important role in bleomycin-induced pulmonary fibrosis, and epalrestat inhibited the progression of bleomycin-induced pulmonary fibrosis is mediated via inhibiting of AR expression.

• Tuberculosis and Respiratory Diseases
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• v.67 no.4
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• pp.275-280
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• 2009

Interstitial lung disease (ILD) is a group of diseases characterized by pulmonary interstitial inflammation. Finally the inflammation results in pulmonary fibrosis and impairment of oxygen transportation. The causes of idiopathic interstitial pneumonia (IIP) are unknown. Diagnosis of IIP is not easy, especially distinguising between nonspecific interstitial pneumonia and usual interstitial pneumonia (UIP). First line treatments of IIP include corticosteroids and immune modulators, which have limited effect. Currently, several drugs are being researched to prevent and treat fibrosis. Newer drugs that may useful to treat pulmonary fibrosis include endothelin receptor antagonist, recombinant soluble TNF receptor antagonist, and cotrimoxazole. The causes of IIP are largely unknown, treatment is not specific, and prognosis is poor. Recent studies are underway to investigate the pathogenesis and treatment of IIP and pulmonary fibrosis. As the pathogenesis of IIP is elucidated, better treatments will emerge.

• Toxicological Research
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• v.26 no.3
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• pp.217-222
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• 2010

Many studies have reported that bleomycin, anti-cancer drug, induces pulmonary fibrosis as a side effect. However, few investigations have focused on the dose-response effects of bleomycin on pulmonary fibrosis. Therefore, in the present study, we investigated the effects of different doses of bleomycin in male mice. ICR mice were given 3 consecutive doses of bleomycin: 1, 2, or 4 mg/kg in bleomycin-treated (BT) groups and saline only in vehicle control (VC) groups. The animals were sacrificed at 7 and 24 days postinstillation. The severity of pulmonary fibrosis was evaluated according to inflammatory cell count and lactate dehydrogenase (LDH) activity in the broncho alveolar lavage fluid (BALF), and lung tissues were histologically evaluated after hematoxylin and eosin (H&E), and Masson's trichrome staining. BT groups exhibited changed cellular profiles in BAL fluid compared to the VC group, which had an increased number of total cells, neutrophils, and lymphocytes and a modest increase in the number of macrophages at 7 days post-bleomycin instillation. Moreover, BT groups showed a dose-dependent increase in LDH levels and inflammatory cell counts. However, at 24 days after treatment, collagen deposition, interstitial thickening, and granulomatous lesions were observed in the alveolar spaces in addition to a decrease in inflammatory cells. These results indicate that pulmonary fibrosis induced by 4 mg/kg bleomycin was more severe than that induced by 1 or 2 mg/kg. These data will be utilized in experimental animal models and as basic data to evaluate therapeutic candidates through non-invasive monitoring using the pulmonary fibrosis mouse model established in this study.

• Biomolecules & Therapeutics
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• v.27 no.3
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• pp.318-326
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• 2019

Sphingosine 1-phosphate (S1P) levels are often found to be elevated in serum, bronchoalveolar lavage, and lung tissue of idiopathic pulmonary fibrosis patients and experimental mouse models. Although the roles of sphingosine kinase 1 and S1P receptors have been implicated in fibrosis, the underlying mechanism of fibrosis via Sphingosine 1-phosphate receptor 2 ($S1P_2$) has not been fully investigated. Therefore, in this study, the roles of $S1P_2$ in lung inflammation and fibrosis was investigated by means of a bleomycin-induced lung fibrosis model and lung epithelial cells. Bleomycin was found to induce lung inflammation on day 7 and fibrosis on day 28 of treatment. On the $7^{th}$ day after bleomycin administration, $S1P_2$ deficient mice exhibited significantly less pulmonary inflammation, including cell infiltration and pro-inflammatory cytokine induction, than the wild type mice. On the $28^{th}$ day after bleomycin treatment, severe inflammation and fibrosis were observed in lung tissues from wild type mice, while lung tissues from $S1P_2$ deficient mice showed less inflammation and fibrosis. Increase in TGF-${\beta}1$-induced extracellular matrix accumulation and epithelial-mesenchymal transition were inhibited by JTE-013, a $S1P_2$ antagonist, in A549 lung epithelial cells. Taken together, pro-inflammatory and pro-fibrotic functions of $S1P_2$ were elucidated using a bleomycin-induced fibrosis model. Notably, $S1P_2$ was found to mediate epithelial-mesenchymal transition in fibrotic responses. Therefore, the results of this study indicate that $S1P_2$ could be a promising therapeutic target for the treatment of pulmonary fibrosis.

• Tuberculosis and Respiratory Diseases
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• v.87 no.2
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• pp.123-133
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• 2024

Interstitial lung diseases (ILDs) are a diverse collection of lung disorders sharing similar features, such as inflammation and fibrosis. The diagnosis and management of ILD require a multidisciplinary approach using clinical, radiological, and pathological evaluation. Progressive pulmonary fibrosis (PPF) is a distinct form of progressive and fibrotic disease, occurring in ILD cases other than in idiopathic pulmonary fibrosis (IPF). It is defined based on clinical symptoms, lung function, and chest imaging, regardless of the underlying condition. The progression to PPF must be monitored through a combination of pulmonary function tests (forced vital capacity [FVC] and diffusing capacity of the lung for carbon monoxide), an assessment of symptoms, and computed tomography scans, with regular follow-up. Although the precise mechanisms of PPF remain unclear, there is evidence of shared pathogenetic mechanisms with IPF, contributing to similar disease behavior and worse prognosis compared to non-PPF ILD. Pharmacological treatment of PPF includes immunomodulatory agents to reduce inflammation and the use of antifibrotics to target progressive fibrosis. Nintedanib, a known antifibrotic agent, was found to be effective in slowing IPF progression and reducing the annual rate of decline in FVC among patients with PPF compared to placebos. Nonpharmacological treatment, including pulmonary rehabilitation, supplemental oxygen therapy, and vaccination, also play important roles in the management of PPF, leading to comprehensive care for patients with ILD. Although there is currently no cure for PPF, there are treatments that can help slow the progression of the disease and improve quality of life.