Searching for Novel Candidate Small Molecules for Ameliorating Idiopathic Pulmonary Fibrosis: a Narrative Review

Idiopathic pulmonary fibrosis (IPF) can be defined as a progressive chronic pulmonary disease showing scarring in the lung parenchyma, thereby resulting in increase in mortality and decrease in the quality of life. The pathophysiologic mechanism of fibrosis in IPF is still unclear. Repetitive microinjuries to alveolar epithelium with genetical predisposition and an abnormal restorative reaction accompanied by excessive deposition of collagens are involved in the pathogenesis. Although the two FDA-approved drugs, pirfenidone and nintedanib, are under use for retarding the decline in lung function of patients suffered from IPF, they are not able to improve the survival rate or quality of life. Therefore, a novel therapeutic agent acting on the major steps of the pathogenesis of disease and/or, at least, managing the clinical symptoms of IPF should be developed for the effective regulation of this incurable disease. In the present review, we tried to find a potential of managing the clinical symptoms of IPF by natural products derived from medicinal plants used for controlling the pulmonary inflammatory diseases in traditional Asian medicine. A multitude of natural products have been reported to exert an antifibrotic effect in vitro and in vivo through acting on the epithelial-mesenchymal transition pathway, transforming growth factor (TGF)-β-induced intracellular signaling, and the deposition of extracellular matrix. However, clinical antifibrotic efficacy of these natural products on IPF have not been elucidated yet. Thus, those effects should be proven by further examinations including the randomized clinical trials, in order to develop the ideal and optimal candidate for the therapeutics of IPF.

Regulation of the Gene Expression of Airway MUC5AC Mucin through NF-κκB Signaling Pathway by Artesunate, an Antimalarial Agent

In this study, artesunate, an antimalarial agent, was investigated for its potential effect on the gene expression of airway MUC5AC mucin. The human pulmonary epithelial NCI-H292 cells were pretreated with artesunate for 30 min and then stimulated with phorbol 12-myristate 13-acetate (PMA), for the following 24 h. The effect of artesunate on PMA-induced nuclear factor kappa B (NFkB) signaling pathway was also examined. Artesunate inhibited the glycoprotein production and mRNA expression of MUC5AC mucins, induced by PMA through the inhibition of degradation of inhibitory kappa Bα (IkBα) and NF-kB p65 nuclear translocation.These results suggest artesunate suppresses the gene expression of mucin through regulation of NF-kB signaling pathway, in human pulmonary epithelial cells.

Meclofenamate Suppresses MUC5AC Mucin Gene Expression by Regulating the NF-kB Signaling Pathway in Human Pulmonary Mucoepidermoid NCI-H292 Cells

The current study aimed to reveal the potential effect of meclofenamate, a nonsteroidal anti-inflammatory drug, on the gene expression of airway MUC5AC mucin. Human pulmonary mucoepidermoid NCI-H292 cells were pretreated with meclofenamate for 30 min and stimulated with phorbol 12-myristate 13-acetate (PMA) for 24 h. Thereafter, the effect of meclofenamate on the PMAinduced nuclear factor kappa B (NF-kB) signaling pathway was assessed. Meclofenamate inhibited glycoprotein production and mRNA expression of MUC5AC mucins induced by PMA by inhibiting the degradation of inhibitory kappa Bα (IkBα) and NF-kB p65 nuclear translocation. These results suggest meclofenamate suppresses mucin gene expression by regulating NF-kB signaling pathway in human pulmonary epithelial cells.

Kaempferol Regulates the Expression of Airway MUC5AC Mucin Gene via IκBα-NF-κB p65 and p38-p44/42-Sp1 Signaling Pathways

In the present study, kaempferol, a flavonoidal natural compound found in Polygonati Rhizoma, was investigated for its potential effect on the gene expression and production of airway MUC5AC mucin. A human respiratory epithelial NCI-H292 cells was pretreated with kaempferol for 30 min and stimulated with epidermal growth factor (EGF) or phorbol 12-myristate 13-acetate (PMA), for the following 24 h. The effect on PMA-induced nuclear factor kappa B (NF-κB) signaling pathway or EGF-induced mitogen-activated protein kinase (MAPK) signaling pathway was investigated. Kaempferol suppressed the production and gene expression of MUC5AC mucins, induced by PMA through the inhibition of degradation of inhibitory kappa Bα (IκBα), and NF-κB p65 nuclear translocation. Also, kaempferol inhibited EGF-induced gene expression and production of MUC5AC mucin through regulating the phosphorylation of EGFR, phosphorylation of p38 MAPK and extracellular signal-regulated kinase (ERK) 1/2 (p44/42), and the nuclear expression of specificity protein-1 (Sp1). These results suggest kaempferol regulates the gene expression and production of mucin through regulation of NF-κB and MAPK signaling pathways, in human airway epithelial cells.

Kaempferol Regulates the Expression of Airway MUC5AC Mucin Gene via IκBα-NF-κB p65 and p38-p44/42-Sp1 Signaling Pathways

In the present study, kaempferol, a flavonoidal natural compound found in Polygonati Rhizoma, was investigated for its potential effect on the gene expression and production of airway MUC5AC mucin. A human respiratory epithelial NCI-H292 cells was pretreated with kaempferol for 30 min and stimulated with epidermal growth factor (EGF) or phorbol 12-myristate 13-acetate (PMA), for the following 24 h. The effect on PMA-induced nuclear factor kappa B (NF-κB) signaling pathway or EGF-induced mitogen-activated protein kinase (MAPK) signaling pathway was investigated. Kaempferol suppressed the production and gene expression of MUC5AC mucins, induced by PMA through the inhibition of degradation of inhibitory kappa Bα (IκBα), and NF-κB p65 nuclear translocation. Also, kaempferol inhibited EGF-induced gene expression and production of MUC5AC mucin through regulating the phosphorylation of EGFR, phosphorylation of p38 MAPK and extracellular signal-regulated kinase (ERK) 1/2 (p44/42), and the nuclear expression of specificity protein-1 (Sp1). These results suggest kaempferol regulates the gene expression and production of mucin through regulation of NF-κB and MAPK signaling pathways, in human airway epithelial cells.

Eriodictyol Inhibits the Production and Gene Expression of MUC5AC Mucin via the IκBα-NF-κB p65 Signaling Pathway in Airway Epithelial Cells

In this study, we investigated whether eriodictyol exerts an effect on the production and gene expression of MUC5AC mucin in human pulmonary epithelial NCI-H292 cells. The cells were pretreated with eriodictyol for 30 min and then stimulated with phorbol 12-myristate 13-acetate (PMA) for 24 h. The effect of eriodictyol on PMA-induced nuclear factor kappa B (NF-κB) signaling pathway was also investigated. Eriodictyol suppressed the MUC5AC mucin production and gene expression induced by PMA via suppression of inhibitory kappa Bα degradation and NF-κB p65 nuclear translocation. These results suggest that eriodictyol inhibits mucin gene expression and production in human airway epithelial cells via regulation of the NF-κB signaling pathway.

Small Molecule Drug Candidates for Managing the Clinical Symptoms of COVID-19: a Narrative Review

Towards the end of 2019, an atypical acute respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in Wuhan, China and subsequently named Coronavirus disease 2019 (COVID-19). The rapid dissemination of COVID-19 has provoked a global crisis in public health. COVID-19 has been reported to cause sepsis, severe infections in the respiratory tract, multiple organ failure, and pulmonary fibrosis, all of which might induce mortality. Although several vaccines for COVID-19 are currently being administered worldwide, the COVID-19 pandemic is not yet effectively under control.Therefore, novel therapeutic agents to eradicate the cause of the disease and/or manage the clinical symptoms of COVID-19 should be developed to effectively regulate the current pandemic. In this review, we discuss the possibility of managing the clinical symptoms of COVID-19 using natural products derived from medicinal plants used for controlling pulmonary inflammatory diseases in folk medicine. Diverse natural products have been reported to exert potential antiviral effects in vitro by affecting viral replication, entry into host cells, assembly in host cells, and release. However, the in vivo antiviral effects and clinical antiviral efficacies of these natural products against SARS-CoV-2 have not been successfully proven to date. Thus, these properties need to be elucidated through further investigations, including randomized clinical trials, in order to develop optimal and ideal therapeutic candidates for COVID-19.

Diclofenac Inhibits Phorbol Ester-Induced Gene Expression and Production of MUC5AC Mucin via Affecting Degradation of IkBα and Translocation of NF-kB p65 in NCI-H292 Cells

In this study, diclofenac, a non-steroidal anti-inflammatory drug, was investigated for its potential effect on the gene expression and production of airway MUC5AC mucin. The human respiratory epithelial NCI-H292 cells were pretreated with diclofenac for 30 min and stimulated with phorbol 12-myristate 13-acetate (PMA), for the following 24 h. The effect of diclofenac on PMA-induced nuclear factor kappa B (NF-kB) signaling pathway was also investigated. Diclofenac suppressed the production and gene expression of MUC5AC mucins, induced by PMA through the inhibition of degradation of inhibitory kappa Bα (IkBα) and NF-kB p65 nuclear translocation. These results suggest diclofenac regulates the gene expression and production of mucin through regulation of NF-kB signaling pathway, in human airway epithelial cells.

Recent Advances in the Development of Novel Drug Candidates for Regulating the Secretion of Pulmonary Mucus

Hypersecretion of pulmonary mucus is a major pathophysiological feature in allergic and inflammatory respiratory diseases including asthma and chronic obstructive pulmonary disease (COPD). Overproduction and/or oversecretion of mucus cause the airway obstruction and the colonization of pathogenic microbes. Developing a novel pharmacological agent to regulate the production and/or secretion of pulmonary mucus can be a useful strategy for the effective management of pathologic hypersecretion of mucus observed in COPD and asthma. Thus, in the present review, we tried to give an overview of the conventional pharmacotherapy for mucus-hypersecretory diseases and recent research results on searching for the novel candidate agents for controlling of pulmonary mucus hypersecretion, aiming to shed light on the potential efficacious pharmacotherapy of mucus-hypersecretory diseases.

Growth Factor- and Phorbol Ester-induced Production and Gene Expression of MUC5AC Mucin in Human Airway Epithelial NCI-H292 Cells Were Inhibited by Afzelin and Natural Products Derived from Houttuynia Cordata

In the present study, we investigated whether quercitrin, quercetin and afzelin derived from Houttuynia cordata affect the production and gene expression of MUC5AC mucin from airway epithelial cells. Confluent NCI-H292 cells were pretreated with quercitrin, quercetin or afzelin for 30 min and then stimulated with epidermal growth factor (EGF) or phorbol 12-myristate 13-acetate (PMA) for 24 h. The MUC5AC mucin gene expression and production were measured by RT-PCR and ELISA, respectively. The results were as follows: (1) Quercitrin, quercetin and afzelin inhibited EGF- and PMA-induced MUC5AC mucin production from NCI-H292 cells; (2) The three natural products also decreased EGF- and PMA-induced MUC5AC mucin gene expression in NCI-H292 cells. These results suggest that quercitrin, quercetin and afzelin showed the regulatory effect on the steps of gene expression and production of mucin, by directly acting on airway epithelial cells.

Effect of Pyunkang-tang on Inflammatory Aspects of Chronic Obstructive Pulmonary Disease in a Rat Model

We investigated the anti-inflammatory effect of Pyunkang-tang extract (PGT), a complex herbal extract based on traditional Chinese medicine that is used in Korea for controlling diverse pulmonary diseases, on cigarette smoke-induced pulmonary pathology in a rat model of chronic obstructive pulmonary disease (COPD). The constituents of PGT were Lonicerae japonica, Liriope platyphylla, Adenophora triphilla, Xantium strumarinum, Selaginella tamariscina and Rehmannia glutinosa. Rats were exposed by inhalation to a mixture of cigarette smoke extract (CSE) and sulfur dioxide for three weeks to induce COPD-like pulmonary inflammation. PGT was administered orally to rats and pathological changes to the pulmonary system were examined in each group of animals through measurement of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels in bronchoalveolar lavage fluid (BALF) at 21 days post-CSE treatment. The effect of PGT on the hypersecretion of pulmonary mucin in rats was assessed by quantification of the amount of mucus secreted and by examining histopathologic changes in tracheal epithelium. Confluent NCI-H292 cells were pretreated with PGT for 30 min and then stimulated with CSE plus PMA (phorbol 12-myristate 13-acetate), for 24 h. The MUC5AC mucin gene expression was measured by RT-PCR. Production of MUC5AC mucin protein was measured by ELISA. The results were as follows: (1) PGT inhibited CSE-induced pulmonary inflammation as shown by decreased TNF-α and IL-6 levels in BALF; (2) PGT inhibited the hypersecretion of pulmonary mucin and normalized the increased amount of mucosubstances in goblet cells of the CSE-induced COPD rat model; (3) PGT inhibited CSE-induced MUC5AC mucin production and gene expression in vitro in NCI-H292 cells, a human airway epithelial cell line. These results suggest that PGT might regulate the inflammatory aspects of COPD in a rat model.

Natural Products as Sources of Novel Drug Candidates for the Pharmacological Management of Osteoarthritis: A Narrative Review

Osteoarthritis is a chronic degenerative articular disorder. Formation of bone spurs, synovial inflammation, loss of cartilage, and underlying bone restructuring have been reported to be the main pathologic characteristics of osteoarthritis symptoms. The onset and progression of osteoarthritis are attributed to various inflammatory cytokines in joint tissues and fluids that are produced by chondrocytes and/or interact with chondrocytes, as well as to low-grade inflammation in intra-articular tissues. Disruption of the equilibrium between the synthesis and degradation of the cartilage of the joint is the major cause of osteoarthritis. Hence, developing a promising pharmacological tool to restore the equilibrium between the synthesis and degradation of osteoarthritic joint cartilage can be a useful strategy for effectively managing osteoarthritis. In this review, we provide an overview of the research results pertaining to the search for a novel candidate agent for osteoarthritis management via restoration of the equilibrium between cartilage synthesis and degradation. We especially focused on investigations of medicinal plants and natural products derived from them to shed light on the potential pharmacotherapy of osteoarthritis.

Molecular Pathophysiology of Ossification of the Posterior Longitudinal Ligament (OPLL)

Ossification of the posterior longitudinal ligament (OPLL) can be defined as an ectopic ossification in the tissues of spinal ligament showing a hyperostotic condition. OPLL is developed mostly in the cervical spine and clinical presentations of OPLL are majorly myelopathy and/or radiculopathy, with serious neurological pathology resulting in paralysis of extremities and disturbances of motility lowering the quality of life. OPLL is known to be an idiopathic and multifactorial disease, which genetic factors and non-genetic factors including diet, obesity, physical strain on the posterior longitudinal ligament, age, and diabetes mellitus, are involved into the pathogenesis. Up to now, surgical management by decompressing the spinal cord is regarded as standard treatment for OPLL, although there might be the risk of development of reprogression of ossification. The molecular pathogenesis and efficient therapeutic strategy, especially pharmacotherapy and/or preventive intervention, of OPLL has not been clearly elucidated and suggested. Therefore, in this review, we tried to give an overview to the present research results on OPLL, in order to shed light on the potential pharmacotherapy based on molecular pathophysiologic aspect of OPLL, especially on the genetic/genomic factors involved into the etiology of OPLL.

Inhibition of the Expression of Matrix Metalloproteinases in Articular Chondrocytes by Resveratrol through Affecting Nuclear Factor-Kappa B Signaling Pathway

In the present study, we tried to examine whether resveratrol regulates the expression of matrix metalloproteinases (MMPs) through affecting nuclear factor-kappa B (NF-κB) in articular chondrocytes. Rabbit articular chondrocytes were cultured in a monolayer, and reverse transcription-polymerase chain reaction (RT-PCR) was used to measure interleukin-1β (IL-1β)-induced gene expression of MMP-3, MMP-1, MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), ADAMTS-5 and type II collagen. Effect of resveratrol on IL-1β-induced secretion of MMP-3 was investigated in rabbit articular chondrocytes using western blot analysis. To elucidate the action mechanism of resveratrol, effect of resveratrol on IL-1β-induced NF-κB signaling pathway was investigated in SW1353, a human chondrosarcoma cell line, by western blot analysis. The results were as follows: (1) resveratrol inhibited the gene expression of MMP-3, MMP-1, MMP-13, ADAMTS-4, and ADAMTS-5, but increased the gene expression of type II collagen; (2) resveratrol reduced the secretion of MMP-3; (3) resveratrol inhibited IL-1β-induced activation (phosphorylation) of inhibitory kappa B kinase (IKK), and thus phosphorylation and degradation of inhibitory kappa Bα (IκBα); (4) resveratrol inhibited IL-1β-induced phosphorylation and nuclear translocation of NF-κB p65. This, in turn, led to the down-regulation of gene expression of MMPs in SW1353 cells. These results suggest that resveratrol can regulate the expression of MMPs through affecting NF-κB by directly acting on articular chondrocytes.

Tussilagone suppressed the production and gene expression of MUC5AC mucin via regulating nuclear factor-kappa B signaling pathway in airway epithelial cells

In the present study, we investigated whether tussilagone, a natural product derived from Tussilago farfara, significantly affects the production and gene expression of airway MUC5AC mucin. Confluent NCI-H292 cells were pretreated with tussilagone for 30 min and then stimulated with EGF (epidermal growth factor) or PMA (phorbol 12-myristate 13-acetate) for 24 h or the indicated periods. The MUC5AC mucin gene expression was measured by RT-PCR. Production of MUC5AC mucin protein was measured by ELISA. To elucidate the action mechanism of tussilagone, effect of tussilagone on PMA-induced NF-κB signaling pathway was investigated by western blot analysis. Tussilagone significantly inhibited the production of MUC5AC mucin protein and down-regulated the expression of MUC5AC mucin gene, induced by EGF or PMA. Tussilagone inhibited PMA-induced activation (phosphorylation) of inhibitory kappa B kinase (IKK), and thus phosphorylation and degradation of inhibitory kappa Ba (IκBα). Tussilagone inhibited PMA-induced phosphorylation and nuclear translocation of nuclear factor kappa B (NF-κB) p65. This, in turn, led to the down-regulation of MUC5AC protein production in NCI-H292 cells. These results suggest that tussilagone can regulate the production and gene expression of mucin by acting on airway epithelial cells through regulation of NF-κB signaling pathway.

Effects of Homogentisic Acid and Natural Products Derived from Pinellia ternata on Secretion, Production and Gene Expression of MUC5AC Mucin from Cultured Airway Epithelial Cells

In this study, we investigated whether adenosine, adenine, uridine and homogentisic acid derived from Pinellia ternata affect the secretion, production and gene expression of MUC5AC mucin from airway epithelial cells. Confluent NCI-H292 cells were pretreated with adenosine, adenine, uridine or homogentisic acid for 30 min and then stimulated with PMA (phorbol 12-myristate 13-acetate) for 24 h. The MUC5AC mucin gene expression, mucin protein production and secretion were measured by RT-PCR and ELISA, respectively. The results were as follows: (1) Adenine and homogentisic acid decreased PMA-induced MUC5AC mucin gene expression, although adenosine and uridine did not affect the mucin gene expression; (2) Adenosine, adenine, uridine and homogentisic acid inhibited PMA-induced MUC5AC mucin production; (3) Homogentisic acid inhibited the secretion of MUC5AC mucin from NCI-H292 cells. These results suggest that, among the four compounds examined, homogentisic acid showed the regulatory effect on the steps of gene expression, production and secretion of mucin, by directly acting on airway epithelial cells.

Effects of Nodakenin, Columbianadin, and Umbelliferone Isolated from the Roots of Angelica decursiva on the Gene Expression and Production of MUC5AC Mucin from Human Airway Epithelial NCI-H292 Cells

Angelica decursiva has been utilised as remedy for controlling the airway inflammatory diseases in folk medicine. We investigated whether nodakenin, columbianadin, and umbelliferone isolated from the roots of Angelica decursiva inhibit the gene expression and production of MUC5AC mucin from human airway epithelial cells. Confluent NCI-H292 cells were pretreated with nodakenin, columbianadin or umbelliferone for 30 min and then stimulated with epidermal growth factor (EGF), phorbol 12-myristate 13-acetate (PMA) or tumor necrosis factor-α (TNF-α) for 24 h. The MUC5AC mucin gene expression was measured by reverse transcription - polymerase chain reaction (RT-PCR). Production of MUC5AC mucin protein was measured by enzyme-linked immunosorbent assay (ELISA). The results were as follows: (1) Nodakenin did not affect the expression of MUC5AC mucin gene induced by EGF, PMA or TNF-α. Columbianadin inhibited the expression of MUC5AC mucin gene induced by EGF or PMA. However, umbelliferone inhibited the expression of MUC5AC mucin gene induced by EGF, PMA or TNF-α; (2) Nodakenin also did not affect the production of MUC5AC mucin protein induced by EGF, PMA or TNF-α. Columbianadin inhibited the production of MUC5AC mucin protein induced by PMA. However, umbelliferone inhibited the production of MUC5AC mucin protein induced by EGF, PMA or TNF-α. These results suggest that, among the three compounds investigated, umbelliferone only inhibits the gene expression and production of MUC5AC mucin stimulated by various inducers, by directly acting on airway epithelial cells, and the results might explain the traditional use of Angelica decursiva as remedy for diverse inflammatory pulmonary diseases.

Betulin suppressed interleukin-1β-induced gene expression, secretion and proteolytic activity of matrix metalloproteinase in cultured articular chondrocytes and production of matrix metalloproteinase in the knee joint of rat

We investigated whether betulin affects the gene expression, secretion and proteolytic activity of matrix metalloproteinase-3 (MMP-3) in primary cultured rabbit articular chondrocytes, as well as in vivo production of MMP-3 in the rat knee joint to evaluate the potential chondroprotective effect of betulin. Rabbit articular chondrocytes were cultured and reverse transcription-polymerase chain reaction (RT-PCR) was used to measure interleukin-1β (IL-1β)-induced gene expression of MMP-3, MMP-1, MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), ADAMTS-5 and type II collagen. Effect of betulin on IL-1β-induced secretion and proteolytic activity of MMP-3 was investigated using western blot analysis and casein zymography, respectively. Effect of betulin on MMP-3 protein production was also examined in vivo. The results were as follows: (1) betulin inhibited the gene expression of MMP-3, MMP-1, MMP-13, ADAMTS-4, and ADAMTS-5, but increased the gene expression of type II collagen; (2) betulin inhibited the secretion and proteolytic activity of MMP-3; (3) betulin suppressed the production of MMP-3 protein in vivo. These results suggest that betulin can regulate the gene expression, secretion, and proteolytic activity of MMP-3, by directly acting on articular chondrocytes.

Erratum to: Betulin suppressed interleukin-1b-induced gene expression, secretion and proteolytic activity of matrix metalloproteinase in cultured articular chondrocytes and production of matrix metalloproteinase in the knee joint of rat

Due to an oversight of the editorial team, the original version of this article contained an error in the list of authors.

Effect of oleanolic acid on the activity, secretion and gene expression of matrix metalloproteinase-3 in articular chondrocytes in vitro and the production of matrix metalloproteinase-3 in vivo

In the present study, we tried to examine whether oleanolic acid regulates the activity, secretion and gene expression of matrix metalloproteinase-3 (MMP-3) in primary cultured rabbit articular chondrocytes, as well as the production of MMP-3 in the knee joint of rat to evaluate the potential chondroprotective effect of oleanolic acid. Rabbit articular chondrocytes were cultured in a monolayer, and reverse transcription-polymerase chain reaction (RT-PCR) was used to measure interleukin-1β (IL-1β)-induced gene expression of MMP-3, MMP-1, MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), ADAMTS-5 and type II collagen. In rabbit articular chondrocytes, the effects of oleanolic acid on IL-1β-induced secretion and proteolytic activity of MMP-3 were investigated using western blot analysis and casein zymography, respectively. The effect of oleanolic acid on in vivo MMP-3 protein production was also examined, after intra-articular injection to the knee joint of rat. The results were as follows: (1) oleanolic acid inhibited the gene expression of MMP-3, MMP-1, MMP-13, ADAMTS-4, and ADAMTS-5, but increased the gene expression of type II collagen; (2) oleanolic acid reduced the secretion and proteolytic activity of MMP-3; (3) oleanolic acid suppressed the production of MMP-3 protein in vivo. These results suggest that oleanolic acid can regulate the activity, secretion and gene expression of MMP-3, by directly acting on articular chondrocytes.