Calcitriol inhibits bleomycin-induced early pulmonary inflammatory response and epithelial-mesenchymal transition in mice

Modeling of Respiratory Diseases Evolving with Fibrosis from Organoids Derived from Human Pluripotent Stem Cells

Respiratory disease is one of the leading causes of morbidity and mortality worldwide. There is no cure for most diseases, which are treated symptomatically. Hence, new strategies are required to deepen the understanding of the disease and development of therapeutic strategies. The advent of stem cell and organoid technology has enabled the development of human pluripotent stem cell lines and adequate differentiation protocols for developing both airways and lung organoids in different formats. These novel human-pluripotent-stem-cell-derived organoids have enabled relatively accurate disease modeling. Idiopathic pulmonary fibrosis is a fatal and debilitating disease that exhibits prototypical fibrotic features that may be, to some extent, extrapolated to other conditions. Thus, respiratory diseases such as cystic fibrosis, chronic obstructive pulmonary disease, or the one caused by SARS-CoV-2 may reflect some fibrotic aspects reminiscent of those present in idiopathic pulmonary fibrosis. Modeling of fibrosis of the airways and the lung is a real challenge due to the large number of epithelial cells involved and interaction with other cell types of mesenchymal origin. This review will focus on the status of respiratory disease modeling from human-pluripotent-stem-cell-derived organoids, which are being used to model several representative respiratory diseases, such as idiopathic pulmonary fibrosis, cystic fibrosis, chronic obstructive pulmonary disease, and COVID-19.

A novel and low-toxic peptide DR3penA alleviates pulmonary fibrosis by regulating the MAPK/miR-23b-5p/AQP5 signaling axis

Pulmonary fibrosis (PF) is a pathological change caused by repeated injuries and repair dysfunction of the alveolar epithelium. Our previous study revealed that the residues Asn3 and Asn4 of peptide DR8 (DHNNPQIR-NH₂) could be modified to improve stability and antifibrotic activity, and the unnatural hydrophobic amino acids α-(4-pentenyl)-Ala and d-Ala were considered in this study. DR3penA (DHα-(4-pentenyl)-ANPQIR-NH₂) was verified to have a longer half-life in serum and to significantly inhibit oxidative damage, epithelial-mesenchymal transition (EMT) and fibrogenesis in vitro and in vivo. Moreover, DR3penA has a dosage advantage over pirfenidone through the conversion of drug bioavailability under different routes of administration. A mechanistic study revealed that DR3penA increased the expression of aquaporin 5 (AQP5) by inhibiting the upregulation of miR-23b-5p and the mitogen-activated protein kinase (MAPK) pathway, indicating that DR3penA may alleviate PF by regulating MAPK/miR-23b-5p/AQP5. Safety evaluation showed that DR3penA is a peptide drug without obvious toxicity or acute side effects and has significantly improved safety compared to DR8. Thus, our findings suggest that DR3penA, as a novel and low-toxic peptide, has the potential to be a leading compound for PF therapy, which provides a foundation for the development of peptide drugs for fibrosis-related diseases.

The Role of Serum 1,25-Dihydroxy Vitamin D3 and PCT in Idiopathic Pulmonary Fibrosis

OBJECTIVE

Biomarkers for the acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) are urgently needed to provide better patient management. We aimed to investigate whether serum 1,25(OH)2D3 (1,25-dihydroxy vitamin D3) levels predict AE-IPF and whether they could be a potential prognostic biomarker for IPF.

PARTICIPANTS AND METHODS

This prospective study included 72 patients with IPF (31 with stable IPF and 41 with AE-IPF). All participants were recruited during hospitalisation at Tianjin Chest Hospital and were followed up for at least 12 months. Demographics, comorbidities, arterial blood gas, and serum biochemical profile, radiological features, and anti-fibrotic therapy were evaluated. Serum concentrations of 1,25(OH)2D3 and transforming growth factor beta1 (TGFβ1) were detected using enzyme-linked immunosorbent assay (ELISA). Risk factors for AE-IPF were identified using multivariate analysis. Prognostic factors were assessed using Kaplan-Meier and Cox regression analyses.

RESULTS

Baseline values of alveolar-arterial oxygen difference (A-aDO2) (40.85 mmHg vs 29.2 mmHg, p =0.035), white blood cell counts (10.09 ± 4.2×109/L vs 7.46 ± 7.84×109/L, p <0.001), percentage of monocytes (7.36 ± 1.36% vs 6.6 ± 1.2%, p =0.017), C-reactive protein (CRP) (2.1 mg/dL vs 1.12 mg/dL, p =0.015) and procalcitonin (PCT) (36.59% vs 3.23%, p <0.001) were significantly higher in AE-IPF patients than in stable IPF patients. Instead, the mean concentration of serum calcium and 1,25(OH)2D3 at baseline were higher in IPF patients with stable disease than in those with acute exacerbation (2.17 ± 0.13 nmol/L vs 2.09 ± 0.13 nmol/L, p =0.023 and 16.62 pg/mL vs 11.58 pg/mL, p <0.001, respectively). In multivariate analysis, a higher proportion of patients with lower serum 1,25(OH)2D3 levels experienced AE-IPF (OR 0.884, 95% CI 0.791-0.987, p =0.029), and rising serum PCT level (PCT > 0.05 ng/mL) was associated with an increased risk of mortality (HR 3.664, 95% CI 1.010-12.900, p =0.043).

CONCLUSION

Decreased serum 1,25(OH)2D3 is associated with an increased risk of acute exacerbation for patients with IPF. A high serum PCT level is predictive of worse prognosis in IPF patients. 1,25(OH)2D3 may be a potential biomarker for AE-IPF, while PCT could be a prognostic biomarker for IPF.

Shared mechanisms and crosstalk of COVID-19 and osteoporosis via vitamin D

Recently accumulated evidence implicates a close association of vitamin D (VitD) insufficiency to the incidence and clinical manifestations of the COVID-19 caused by severe acute respiratory syndrome coronavirus-2 (SARS-COV-2). Populations with insufficient VitD including patients with osteoporosis are more susceptible to SARS-COV-2 infection and patients with COVID-19 worsened or developed osteoporosis. It is currently unknown, however, whether osteoporosis and COVID-19 are linked by VitD insufficiency. In this study, 42 common targets for VitD on both COVID-19 and osteoporosis were identified among a total of 243 VitD targets. Further bioinformatic analysis revealed 8 core targets (EGFR, AR, ESR1, MAPK8, MDM2, EZH2, ERBB2 and MAPT) in the VitD-COVID-19-osteoporosis network. These targets are involved in the ErbB and MAPK signaling pathways critical for lung fibrosis, bone structural integrity, and cytokines through a crosstalk between COVID-19 and osteoporosis via the VitD-mediated conventional immune and osteoimmune mechanisms. Molecular docking confirmed that VitD binds tightly to the predicted targets. These findings support that VitD may target common signaling pathways in the integrated network of lung fibrosis and bone structural integrity as well as the immune systems. Therefore, VitD may serve as a preventive and therapeutic agent for both COVID-19 and osteoporosis.

Effects of Hypocalcemic Vitamin D Analogs in the Expression of DNA Damage Induced in Minilungs from hESCs: Implications for Lung Fibrosis

In our previous work, we evaluated the therapeutic effects of 1α,25-Dihydroxyvitamin D₃, the biologically active form of vitamin D, in the context of bleomycin-induced lung fibrosis. Contrary to the expected, vitamin D supplementation increased the DNA damage expression and cellular senescence in alveolar epithelial type II cells and aggravated the overall lung pathology induced in mice by bleomycin. These effects were probably due to an alteration in the cellular DNA double-strand breaks’ repair capability. In the present work, we have evaluated the effects of two hypocalcemic vitamin D analogs (calcipotriol and paricalcitol) in the expression of DNA damage in the context of minilungs derived from human embryonic stem cells and in the cell line A549.

Vitamin D Actions: The Lung Is a Major Target for Vitamin D, FGF23, and Klotho

Vitamin D is well known for its role as a calcium regulator and in maintenance of phosphate homeostasis in musculoskeletal health, and fibroblast growth factor 23 (FGF23) and its coreceptor α-klotho are known for their roles as regulators of serum phosphate levels. However, apart from these classical actions, recent data point out a relevant role of vitamin D and FGF23/klotho in lung health. The expression of the vitamin D receptor by different cell types in the lung and the fact that those cells respond to vitamin D or can locally produce vitamin D indicate that the lung represents a target for vitamin D actions. Similarly, the presence of the four FGF receptor isoforms in the lung and the ability of FGF23 to stimulate pulmonary cells support the concept that the lung is a target for FGF23 actions, whereas the contribution of klotho is still undetermined. This review will give an overview on how vitamin D or FGF23/klotho may act on the lung and interfere positively or negatively with lung health. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Inhaled B7 alleviates bleomycin-induced pulmonary fibrosis in mice

Treatment options for the progression of pulmonary fibrosis (PF), which ultimately causes respiratory failure, are limited. According to recent studies, recombinant human relaxin is potentially therapeutic against fibrosis and contraction during pulmonary damage. However, the production of recombinant H2 relaxin is laborious and expensive, limiting its extensive application. Thankfully, alternative research has revealed that treatment with a single-chain peptide of relaxin attenuates organ fibrosis in rodent models too, with the production of a single-chain peptide of relaxin simple and cheap; it could be therapeutic against idiopathic pulmonary fibrosis. Here, we explored the probable inhibiting effects of B7, a B chain of recombinant human relaxin, on bleomycin-induced pulmonary inflammation. Inhaled B7 efficiently reduced the number of inflammatory leukocytes and neutrophils in the bronchoalveolar lavage fluid of mice with bleomycin-induced PF, significantly improved the structure of the damaged alveolar, reduced collagen deposition, suppressed the main pathological features of idiopathic pulmonary fibrosis, i.e. the expression of both pulmonary α-smooth muscle actin and pulmonary vimentin, and inhibited the transcription of inflammation and collagen deposition-related mRNAs, including fibronectin, α-smooth muscle actin (α-SMA), interleukin-1β (IL-1β), interleukin-6 (IL-6), and alpha-1 type 1 collagen (Col-1a), and the expression of inflammation-related proteins, such as IL-1β, IL-6, chemokines (KC), TIMP metallopeptidase inhibitor 1 (TIMP-1), and hydroxyproline (Hyp). Overall, our findings suggest that inhaled B7 exerts beneficial effects against pulmonary fibrosis via attenuating inflammation. It could be developed into a simple, highly effective therapeutic approach for pulmonary fibrosis.

Vitamin D3 alleviates pulmonary fibrosis by regulating the MAPK pathway via targeting PSAT1 expression in vivo and in vitro

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal fibrotic lung disease. However, there are insufficient drugs available for IPF treatment, and the currently used drugs are accompanied by many adverse reactions. Deficiency of vitamin D3 (VD3) in the development of IPF and the potential role of VD3 in the treatment of IPF have attracted increasing attention. In vivo experimental results showed that VD3 could increase the survival rate in bleomycin (BLM)-induced models, relieve lung inflammation, reduce hydroxyproline content, and inhibit collagen deposition and cell apoptosis. We further performed proteomics analysis and screened 251 target proteins that reflect VD3 intervention in BLM-induced animal models. These target proteins were involved in acute inflammation, oxidative stress, antioxidant activity and extracellular matrix binding. Combined with the comprehensive analysis of clinical samples, PSAT1 was screened out as a candidate target related to IPF disease and VD3 treatment. Through further computational analysis, the MAPK signaling pathway was considered to be the most probable candidate pathway for VD3 function targeting IPF. In in vivo experiments, VD3 inhibited BLM-induced expression of PSAT1 and phosphorylation of p38 and ERK1/2 in mouse lung tissue. The experiments of cell proliferation and western blot confirmed that VD3 inhibited the expression of PSAT1 and the activation of the mitogen-activated protein kinase (MAPK) pathway in human pulmonary fibroblasts (HPF). Furthermore, experiments with transfection plasmids overexpressing PSAT1 proved that VD3 could attenuate the proliferation and differentiation of HPF by suppressing the effect of PSAT1 on the MAPK signaling pathway. Finally, we confirmed that vitamin D receptor (VDR) could occupy the PSAT1 promoter to reveal the transcriptional regulation effect of VD3 on PSAT1. In conclusion, VD3 exerted a therapeutic effect on IPF by down-regulating the MAPK signaling pathway via targeting the expression of PSAT1.

The inhibitory mechanisms of losartan and vitamin D on amiodarone-induced lung inflammation in rats: Role of mitogen-activated protein kinases/activator protein-1

Amiodarone (AMD), an antiarrhythmic drug, is used cautiously due to its lung toxicity that is characterized by alveolar inflammation followed by fatal fibrosis. AMD induces lung inflammation via increasing the alveolar macrophages and disturbing the balance of T-helper-1 (Th1) and Th2 cells cytokines. In this study, the role of the mitogen-activated protein kinases (MAPKs)/activator protein-1 (AP-1) pathway in AMD-induced lung inflammation was evaluated. Also, the anti-inflammatory and antifibrotic effects of losartan and/or vitamin D were investigated following 7, 14, and 28 days of AMD administration. AMD resulted in lung injury, inflammatory infiltration, and increased pulmonary levels of inflammatory cytokines starting from Week 1 of exposure. A significant increase in serum levels of interleukin-4 along with a significant reduction of interferon-gamma, in addition to strong expression of CD68, were reported after 14 and 28 days of AMD administration reflecting Th1/Th2 cytokines imbalance and the accumulation of alveolar macrophages, respectively. The phosphorylation of MAPKs (ERK1/2, JNK, p38) and AP-1 was significantly enhanced starting from Week 1 of exposure. Marked expression of transforming growth factor beta-1 and massive deposition of collagen were detected after 28 days reflecting late fibrosis. All these abnormalities were significantly mitigated by vitamin D and its combination with losartan. Losartan alone has less prominent anti-inflammatory effects particularly after 28 days; however, it efficiently prevented late fibrosis. This study concludes that MAPKs/AP-1 pathway is involved in AMD-induced lung inflammation and that vitamin D and/or losartan could be used as a prophylactic agent to prevent AMD-induced lung toxicity.

Tauroursodeoxycholic acid alleviates pulmonary endoplasmic reticulum stress and epithelial-mesenchymal transition in bleomycin-induced lung fibrosis

Background

Several studies demonstrate that endoplasmic reticulum (ER) stress-mediated epithelial-mesenchymal transition (EMT) is involved in the process of bleomycin (BLM)-induced pulmonary fibrosis. Tauroursodeoxycholic acid (TUDCA), a bile acid with chaperone properties, is an inhibitor of ER stress. This study aimed to investigate the preventive effects of TUDCA on BLM-induced EMT and lung fibrosis.

Methods

The model of lung fibrosis was established by intratracheal injection with a single dose of BLM (3.0 mg/kg). In TUDCA + BLM group, mice were intraperitoneally injected with TUDCA (250 mg/kg) daily.

Results

BLM-induced alveolar septal destruction and inflammatory cell infiltration were alleviated by TUDCA. BLM-induced interstitial collagen deposition, as determined by Sirius Red staining, was attenuated by TUDCA. BLM-induced elevation of pulmonary α-smooth muscle actin (α-SMA) and reduction of pulmonary E-cadherin were attenuated by TUDCA. BLM-induced pulmonary Smad2/3 phosphorylation was suppressed by TUDCA. BLM-induced elevation of Ki67 and PCNA was inhibited by TUDCA in mice lungs. In addition, BLM-induced elevation of HO-1 (heme oxygenase-1) and 3-NT (3-nitrotyrosine) was alleviated by TUDCA. Finally, BLM-induced upregulation of pulmonary GRP78 and CHOP was attenuated by TUDCA.

Conclusions

These results provide evidence that TUDCA pretreatment inhibits Smad2/3-medited EMT and subsequent lung fibrosis partially through suppressing BLM-induced ER stress and oxidative stress.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01514-6.

Supplementation with high-dose cholecalciferol throughout pregnancy induces fetal growth restriction through inhibiting placental proliferation and trophoblast epithelial-mesenchymal transition

Vitamin D deficiency has been associated with adverse pregnant outcomes. Several studies investigated the effects of maternal vitamin D3 supplementation on fetal development with inconsistent results. The aim of this study was to investigate the effects of maternal supplementation with different doses of vitamin D3 on fetal development. Pregnant mice were administered with different doses of cholecalciferol (0, 2,000, 10,000, 40,000 IU/kg/day) by gavage throughout pregnancy. Fetal weight and crown-rump length were measured. Placental proliferation and mesenchymal characteristics were detected. HTR-8/SVneo cells were incubated in the absence or presence of calcitriol (500 nmol/L) to evaluate the effects of active vitamin D3 on migration and invasion of human trophoblast cells. Although a low dose of cholecalciferol was safe, fetal weight and crown-rump length were decreased in dams treated with high-dose cholecalciferol throughout pregnancy. Placental weight and labyrinth thickness were reduced in mice administered with high-dose cholecalciferol. An obvious calcification was observed in placentae of mice administered with high-dose cholecalciferol. Ki67-positive cells, a marker of placental proliferation, were reduced in mice administered with high-dose cholecalciferol. N-cadherin and vimentin, two mesenchymal markers, were decreased in cholecalciferol-treated mouse placentae and calcitriol-treated human trophoblast cells. MMP-2 and MMP-9, two matrix metalloproteinases, were downregulated in cholecalciferol-treated mouse placentae and calcitriol-treated human trophoblast cells. In addition, trophoblast migration and invasion were suppressed by calcitriol. Supplementation with high-dose cholecalciferol induces fetal growth restriction partially through inhibiting placental proliferation and trophoblast epithelial-mesenchymal transition.

Low Vitamin D Status Is Associated with Inflammation in Patients with Chronic Obstructive Pulmonary Disease

Vitamin D deficiency is associated with increased risks of chronic obstructive pulmonary disease (COPD). Nevertheless, the mechanisms remain unknown. This study analyzed the correlations between vitamin D levels and inflammation in COPD patients. One hundred and one patients with COPD and 202 control subjects were enrolled. Serum 25(OH)D level and inflammatory cytokines were detected. Serum 25(OH)D was decreased and inflammatory cytokines were increased in COPD patients. According to forced expiratory volume in 1 s, COPD patients were divided into three grades. Furthermore, serum 25(OH)D was gradually decreased in COPD patients ranging from grade 1-2 to 4. Serum 25(OH)D was inversely associated with inflammatory cytokines in COPD patients. Further analysis found that NF-κB and AP-1 signaling were activated in COPD patients. Besides, inflammatory signaling was gradually increased in parallel with the severity of COPD. By contrast, pulmonary nuclear vitamin D receptor was decreased in COPD patients. In vitro experiments showed that 1,25(OH)₂D₃ inhibited LPS-activated inflammatory signaling in A549 cells (human lung adenocarcinoma cell). Mechanically, 1,25(OH)₂D₃ reinforced physical interactions between vitamin D receptor with NF-κB p65 and c-Jun. Our results indicate that vitamin D is inversely correlated with inflammatory signaling in COPD patients. Inflammation may be a vital mediator of COPD progress in patients with low vitamin D levels.

Vitamin D high doses supplementation could represent a promising alternative to prevent or treat COVID-19 infection

Although we lack enough evidence to justify supplementing with vitamin D in the prevention and treatment of COVID-19 infection, it is increasingly feasible that this hypothesis is valid. Two general underlying mechanisms should be considered. One would be the anti-infectious and immunomodulatory action that it exerts by improving intercellular barriers by stimulating innate immunity, as well as by modulating adaptive immunity. Also, vitamin D reduces the production of inflammatory cytokines, such as IL-2 and interferon-gamma (INFγ). More recently, multiple pleiotropic effects have been demonstrated on the actions of vitamin D at the anti-inflammatory and immunomodulatory level with positive results in studies with influenza, coronavirus, and other respiratory infections. An inverse relationship between serum vitamin D levels and the prevalence of the respiratory infectious disease has been described. Of interest, another mechanistic approach responds to considering the inhibition of the renin-angiotensin-aldosterone system (RAAS), which is exacerbated in COVID-19 infection because the virus binds to the enzyme ACE2, making more angiotensin II available to cause damage. Vitamin D inhibits mediators of RAAS – present in all cells of the body – and by inhibiting ACE activity and increasing ACE2, it lowers angiotensin II levels. We present studies with proposals for recommended doses of vitamin D, and although a single guideline is not specified, the possible benefits are promising. Finally, the purpose of this review is to share this idea with health professionals to ignite the debate and call for critical reflection, so that it can contribute to the undertaking of more and better clinical designs to validate the benefits of using high doses of vitamin D for the benefit of public health and especially in times of crisis for COVID-19.

Vitamin D high doses supplementation could represent a promising alternative to prevent or treat COVID-19 infection

Although we lack enough evidence to justify supplementing with vitaminD in the prevention and treatment of COVID-19 infection, it is increasingly feasible that this hypothesis is valid. Two general underlying mechanisms should be considered. One would be the anti-infectious and immunomodulatory action that it exerts by improving intercellular barriers by stimulating innate immunity, as well as by modulating adaptive immunity. Also, vitaminD reduces the production of inflammatory cytokines, such as IL-2 and interferon-gamma (INF-γ). More recently, multiple pleiotropic effects have been demonstrated on the actions of vitaminD at the anti-inflammatory and immunomodulatory level with positive results in studies with influenza, coronavirus, and other respiratory infections. An inverse relationship between serum vitaminD levels and the prevalence of the respiratory infectious disease has been described. Of interest, another mechanistic approach responds to considering the inhibition of the renin-angiotensin-aldosterone system (RAAS), which is exacerbated in COVID-19 infection because the virus binds to the enzyme ACE2, making more angiotensinII available to cause damage. VitaminD inhibits mediators of RAAS - present in all cells of the body - and by inhibiting ACE activity and increasing ACE2, it lowers angiotensinII levels. We present studies with proposals for recommended doses of vitaminD, and although a single guideline is not specified, the possible benefits are promising. Finally, the purpose of this review is to share this idea with health professionals to ignite the debate and call for critical reflection, so that it can contribute to the undertaking of more and better clinical designs to validate the benefits of using high doses of vitaminD for the benefit of public health and especially in times of crisis for COVID-19.

Vitamin D supplementation as a rational pharmacological approach in the COVID-19 pandemic

The COVID-19 pandemic has reached most of the countries worldwide causing death, which often results from an inflammatory storm associated with severe acute respiratory syndrome (SARS). This has prompted researchers to seek specific novel and definitive treatments urgently. In this context, it is interesting to evaluate the preventive and therapeutic effects of existing pharmacological agents that could be useful. In this regard, vitamin D supplementation, particularly in individuals likely to be deficient, may be a promising option. Vitamin D is a hormone that modulates many of the same inflammatory and oxidative signaling pathways triggered during COVID-19. For example, vitamin D suppresses the actions of the renin-angiotensin system, which has a determining role in the pathophysiology of the inflammatory response related to COVID-19. This paper analyzes the evidence that vitamin D supplementation might be a valuable preventive/therapeutic measure in groups at risk for or infected with COVID-19. It also discusses how clinical studies could be best designed to evaluate the possible advantages of vitamin D supplementation for the benefit of public health during the pandemic.

Natural products as home-based prophylactic and symptom management agents in the setting of COVID-19

Coronavirus disease (COVID‐19) caused by the novel coronavirus (SARS‐CoV‐2) has rapidly spread across the globe affecting 213 countries or territories with greater than six million confirmed cases and about 0.37 million deaths, with World Health Organization categorizing it as a pandemic. Infected patients present with fever, cough, shortness of breath, and critical cases show acute respiratory infection and multiple organ failure. Likelihood of these severe indications is further enhanced by age as well as underlying comorbidities such as diabetes, cardiovascular, or thoracic problems, as well as due to an immunocompromised state. Currently, curative drugs or vaccines are lacking, and the standard of care is limited to symptom management. Natural products like ginger, turmeric, garlic, onion, cinnamon, lemon, neem, basil, and black pepper have been scientifically proven to have therapeutic benefits against acute respiratory tract infections including pulmonary fibrosis, diffuse alveolar damage, pneumonia, and acute respiratory distress syndrome, as well as associated septic shock, lung and kidney injury, all of which are symptoms associated with COVID‐19 infection. This review highlights the potential of these natural products to serve as home‐based, inexpensive, easily accessible, prophylactic agents against COVID‐19.

Impact of the Local Inflammatory Environment on Mucosal Vitamin D Metabolism and Signaling in Chronic Inflammatory Lung Diseases

Vitamin D plays an active role in the modulation of innate and adaptive immune responses as well as in the protection against respiratory pathogens. Evidence for this immunomodulatory and protective role is derived from observational studies showing an association between vitamin D deficiency, chronic airway diseases and respiratory infections, and is supported by a range of experimental studies using cell culture and animal models. Furthermore, recent intervention studies have now shown that vitamin D supplementation reduces exacerbation rates in vitamin D-deficient patients with chronic obstructive pulmonary disease (COPD) or asthma and decreases the incidence of acute respiratory tract infections. The active vitamin D metabolite, 1,25-dihydroxy-vitamin D (1,25(OH)₂D), is known to contribute to the integrity of the mucosal barrier, promote killing of pathogens (via the induction of antimicrobial peptides), and to modulate inflammation and immune responses. These mechanisms may partly explain its protective role against infections and exacerbations in COPD and asthma patients. The respiratory mucosa is an important site of local 1,25(OH)₂D synthesis, degradation and signaling, a process that can be affected by exposure to inflammatory mediators. As a consequence, mucosal inflammation and other disease-associated factors, as observed in e.g., COPD and asthma, may modulate the protective actions of 1,25(OH)₂D. Here, we discuss the potential consequences of various disease-associated processes such as inflammation and exposure to pathogens and inhaled toxicants on vitamin D metabolism and local responses to 1,25(OH)₂D in both immune- and epithelial cells. We furthermore discuss potential consequences of disturbed local levels of 25(OH)D and 1,25(OH)₂D for chronic lung diseases. Additional insight into the relationship between disease-associated mechanisms and local effects of 1,25(OH)₂D is expected to contribute to the design of future strategies aimed at improving local levels of 1,25(OH)₂D and signaling in chronic inflammatory lung diseases.

Lungs as target of COVID-19 infection: Protective common molecular mechanisms of vitamin D and melatonin as a new potential synergistic treatment

COVID-19 pandemic has a high mortality rate and is affecting practically the entire world population. The leading cause of death is severe acute respiratory syndrome as a consequence of exacerbated inflammatory response accompanied by uncontrolled oxidative stress as well as the inflammatory reaction at the lung level. Until now, there is not a specific and definitive treatment for this pathology that worries the world population, especially the older adults who constitute the main risk group. In this context, it results in a particular interest in the evaluation of the efficacy of existing pharmacological agents that may be used for overcoming or attenuating the severity of this pulmonary complication that has ended the lives of many people worldwide. Vitamin D and melatonin could be good options for achieving this aim, taking into account that they have many shared underlying mechanisms that are able to modulate and control the immune adequately and oxidative response against COVID-19 infection, possibly even through a synergistic interaction. The renin-angiotensin system exaltation with consequent inflammatory response has a leading role in the physiopathology of COVID-19 infection; and it may be down-regulated by vitamin D and melatonin in many organs. Therefore, it is also essential to analyze this potential therapeutic association and their relation with RAS as part of this new approach.

Acute 1-NP exposure induces inflammatory responses through activating various inflammatory signaling pathways in mouse lungs and human A549 cells

1-Nitropyrene (1-NP), a key component of fine particulate matter (PM2.5), is a representative of nitrated polycyclic aromatic hydrocarbons (NPAHs). The aim of this research is to investigate proinflammatory effects of acute 1-NP exposure in mouse lungs and human A549 cells. All mice except controls were intratracheally instilled with 1-NP (20 μg/mouse). A549 cell, a human lung cancer cell line, was cultured with or without 1-NP (5 μM). Acute 1-NP exposure elevated lung weight and caused infiltration of inflammatory cells, especially neutrophils in mouse lungs. Although it had little effect on serum TNF-α and KC, acute 1-NP exposure elevated the levels of TNF-α and KC in BALF. Correspondingly, acute 1-NP exposure upregulated pulmonary Il-1β, Il-6, Tnf-α and Kc. Mechanistically, acute 1-NP exposure activated nuclear factor kappa B (NF-κB) in mouse lungs and human A549 cells. Additionally, acute 1-NP exposure induced Akt phosphorylation in mouse lungs and human A549 cells. Moreover, acute 1-NP exposure induced phosphorylation of pulmonary JNK and ERK1/2, molecules of the mitogen-activated protein kinase (MAPK) pathway. This study provides evidence that acute 1-NP exposure induces inflammatory responses through activating various inflammatory signaling pathways in mouse lungs and human A549 cells.

Vitamin D deficiency exacerbates bleomycin-induced pulmonary fibrosis partially through aggravating TGF-β/Smad2/3-mediated epithelial-mesenchymal transition

Background

Our earlier report indicated that active vitamin D3 inhibited epithelial-mesenchymal transition (EMT) in bleomycin (BLM)-induced pulmonary fibrosis. The objective of this study was to further investigate whether vitamin D deficiency exacerbates BLM-induced pulmonary fibrosis.

Methods

This study consists of two independent experiments. Experiment 1, male mice were fed with vitamin D deficient (VDD) fodder. Experiment 2, Cyp27b1^+/+, Cyp27b1^+/− and Cyp27b1^−/− mice were fed with standard diet. For pulmonary fibrosis, mice were intratracheally instilled with a single dose of BLM (1.5 mg/kg). Serum 25(OH) D level was measured. Pulmonary collagen deposition was assessed by Sirius red staining. EMT was measured and transforming growth factor-beta (TGF-β)/Smad3 signaling was evaluated in the lungs of BLM-treated mice.

Results

The relative weight of lungs was elevated in BLM-treated mice. Col1α1 and Col1α2, two collagen protein genes, were upregulated, and collagen deposition, as determined by Sirius red staining, was observed in the lungs of BLM-treated mice. E-cadherin, an epithelial marker, was downregulated. By contrast, vimentin and α-SMA, two EMT markers, were upregulated in the lungs of BLM-treated mice. Pulmonary TGF-β/Smad3 signaling was activated in BLM-induced lung fibrosis. Further analysis showed that feeding VDD diet, leading to vitamin D deficiency, aggravated elevation of BLM-induced relative lung weight. Moreover, feeding VDD diet aggravated BLM-induced TGF-β/Smad3 activation and subsequent EMT in the lungs. In addition, feeding VDD diet exacerbated BLM-induced pulmonary fibrosis. Additional experiment showed that Cyp27b1 gene knockout, leading to active vitamin D3 deficiency, exacerbated BLM-induced pulmonary fibrosis. Moreover, Cyp27b1 gene knockout aggravated pulmonary TGF-β/Smad2/3 activation and subsequent EMT in BLM-induced lung fibrosis.

Conclusion

Vitamin D deficiency exacerbates BLM-induced pulmonary fibrosis partially through aggravating TGF-β/Smad2/3-mediated EMT in the lungs.

Low Vitamin D Status Is Associated with Epithelial-Mesenchymal Transition in Patients with Chronic Obstructive Pulmonary Disease

Vitamin D deficiency is correlated with the increased morbidity of chronic obstructive pulmonary disease (COPD). However, the mechanisms underlying these effects have largely remained elusive. This study analyzed the correlations among COPD, vitamin D concentration, and epithelial-mesenchymal transition (EMT). Ninety-five patients with newly diagnosed COPD and 190 age- and sex-matched healthy subjects were recruited for this research. Serum 25(OH)D levels were detected, and pulmonary EMT biomarkers and TGF-β/Smad signaling were evaluated. Serum 25(OH)D level was remarkably decreased in COPD patients compared with that in control subjects. Furthermore, serum 25(OH)D concentration gradually decreased in COPD patients ranging from grade 1-2 to 4. However, reduced expression of the epithelial biomarker E-cadherin and increased expression of the mesenchymal biomarkers vimentin and α-SMA were found in COPD patients. Mechanistic analysis showed that pulmonary nuclear vitamin D receptor (VDR) was decreased in patients with COPD. In contrast, TGF-β/Smad signaling was obviously activated in COPD patients. Furthermore, the level of serum TGF-β in COPD patients increased in parallel with COPD severity. Serum 25(OH)D concentration was inversely associated with TGF-β levels in COPD patients. In vitro experiments showed that active vitamin D3 inhibits TGF-β-induced Smad2/3 phosphorylation in MRC-5 cells. Furthermore, vitamin D concentration was inversely correlated with TGF-β/Smad signaling and EMT in COPD patients, suggesting EMT as a vital mediator of COPD development in patients with low vitamin D concentrations.

TGF-β1 Impairs Vitamin D-Induced and Constitutive Airway Epithelial Host Defense Mechanisms

Airway epithelium is an important site for local vitamin D (VD) metabolism; this can be negatively affected by inflammatory mediators. VD is an important regulator of respiratory host defense, for example, by increasing the expression of hCAP18/LL-37. TGF-β1 is increased in chronic obstructive pulmonary disease (COPD), and known to decrease the expression of constitutive host defense mediators such as secretory leukocyte protease inhibitor (SLPI) and polymeric immunoglobulin receptor (pIgR). VD has been shown to affect TGF-β1-signaling by inhibiting TGF-β1-induced epithelial-to-mesenchymal transition. However, interactions between VD and TGF-β1, relevant for the understanding host defense in COPD, are incompletely understood. Therefore, the aim of the present study was to investigate the combined effects of VD and TGF-β1 on airway epithelial cell host defense mechanisms. Exposure to TGF-β1 reduced both baseline and VD-induced expression of hCAP18/LL-37, partly by increasing the expression of the VD-degrading enzyme CYP24A1. TGF-β1 alone decreased the number of secretory club and goblet cells and reduced the expression of constitutive host defense mediators SLPI, s/lPLUNC and pIgR, effects that were not modulated by VD. These results suggest that TGF-β1 may decrease the respiratory host defense both directly by reducing the expression of host defense mediators, and indirectly by affecting VD-mediated effects such as expression of hCAP18/LL-37.

Detrimental pro-senescence effects of vitamin D on lung fibrosis

Background

The multiple biological effects of vitamin D and its novel activities on inflammation and redox homeostasis have raised high expectations on its use as a therapeutic agent for multiple fibrogenic conditions. We have assessed the therapeutic effects of 1α,25-Dihydroxyvitamin D₃, the biologically active form of vitamin D, in the context of lung fibrosis.

Methods

We have used representative cellular models for alveolar type II cells and human myofibroblasts. The extension of DNA damage and cellular senescence have been assessed by immunofluorescence, western-blot and senescence-associated β-galactosidase activity. We have also set up a murine model for lung fibrosis by intraperitoneal injections of bleomycin.

Results

Vitamin D induces cellular senescence in bleomycin-treated alveolar epithelial type II cells and aggravates the lung pathology induced by bleomycin. These effects are probably due to an alteration of the cellular DNA double-strand breaks repair in bleomycin-treated cells.

Conclusions

The detrimental effects of vitamin D in the presence of a DNA damaging agent might preclude its use as an antifibrogenic agent for pulmonary fibrosis characterized by DNA damage occurrence and cellular senescence.

Vitamin D treatment abrogates the inflammatory response in paraquat-induced lung fibrosis

A high incidence of intentional or accidental paraquat (PQ) ingestion is related to irreversible lung fibrosis and no effective therapy is currently available. Vitamin D has emerged with promising results as an immunomodulatory molecule when abrogating the inflammatory responses of lung diseases. Therefore, we have investigated the role of vitamin D treatments on PQ-induced lung fibrosis in male C57/BL6 mice. Lung fibrosis was induced by a single injection of PQ (10 mg/kg; i.p.). The control group received PQ vehicle. Seven days later, after the PQ injection or the vehicle injection, the mice received vitamin D (5 μg/kg, i.p., once a day) or vehicle, for a further 7 days. Twenty-four hours after the last dose of vitamin D or the vehicle, the analysis were performed. The vitamin D treatments reduced the number of leukocytes in their BALF and they decreased the IL-6, IL-17, TGF-beta and MMP-9 levels and the abrogated collagenase deposits in their lung tissues. Conversely, the vitamin D treatments increased the resolvin D levels in their BALF. Moreover, their tracheal contractility was also significantly reduced by the vitamin D treatments. Altogether, the data that was obtained showed a promising use of vitamin D, in treating the lung fibrosis that had been induced by the PQ intoxications. This may improve its prognostic use for a non-invasive and low cost therapy.

1&#945;,25-dihydroxyvitamin D3 Attenuates TGF-&#946;-Induced Pro-Fibrotic Effects in Human Lung Epithelial Cells through Inhibition of Epithelial-Mesenchymal Transition

Pulmonary fibrosis is a progressive fibrotic lung disease of persisting lung injury and ineffective wound repair, with poor prognosis. Epithelial-mesenchymal transition (EMT) of alveolar epithelia cells is an early event in the development of pulmonary fibrosis, and transforming growth factor β (TGF-β) is an acknowledged inducer of EMT. Epidemiological studies demonstrated that serum levels of 25-hydroxy-vitamin D were associated with the presence of fibrosis diseases. We investigated whether vitamin D attenuated TGF-β-induced pro-fibrotic effects through inhibiting EMT in human alveolar epithelia A549 cells. A549 cells were cultured with TGF-β alone or in combination with 1α,25-dihydroxyvitamin D3 (1α,25(OH)₂D₃). TGF-β increased the expression of the mesenchymal markers (N-cadherin and Vimentin), and decreased the expression of epithelial markers (E-cadherin). 1α,25(OH)₂D₃ attenuated these TGF-β-induced alterations. Furthermore, the EMT-related transcription factors (Snail and β-catenin) and the extracellular matrix genes (Collagen I and fibronectin) were inhibited by 1α,25(OH)₂D₃, while the expression of vitamin D receptor (VDR) was elevated. In addition, 1α,25(OH)₂D₃ alleviated the cell migration and the invasion abilities in TGF-β-stimulated A549 cells, determined by the scratch wound healing and transwell assays. Our findings suggested that 1α,25(OH)₂D₃ inhibited the pro-fibrotic phenotype of lung epithelial cells under TGF-β stimulation and provided new clues in the clinical management of pulmonary fibrosis.

3-Phosphoinositide Dependent Protein Kinase-1 (PDK-1) Promotes Migration and Invasion in Gastric Cancer Cells Through Activating the NF-κB Pathway

Gastric cancer (GC) is one of the most common cancers and the second leading cause of cancer deaths in the world. Many factors have been reported regarding the progression and development of GC. In this study, we aimed to investigate the correlation of 3-phosphoinositide dependent protein kinase-1 (PDK-1) with cell viability, migration, and invasion of GC. The expression of PDK-1 was measured in different GC cell lines. Thereafter, the expression of PDK-1 was interfered by small hairpin RNA (shRNA) and then incubated with or without the inhibitor of nuclear factor-κB (NF-κB) pyrrolidine dithiocarbamate (PDTC). We then investigated the effects of PDK-1 aberrant expression on GC cell viability, migration, invasion, and the epithelial-mesenchymal transition (EMT) progress. The results showed that PDK-1 was highly expressed in GC cells, and PDK-1 promoted cell viability, migration, invasion, and EMT in GC. Moreover, we confirmed that PDK-1 activated the phosphatidylinositol 3-hydroxy kinase (PI3K)/AKT and NF-κB signaling pathways. However, administration of PDTC reversed the effects of overexpression of PDK-1 on cell migration and invasion. All these findings suggest that PDK-1 may be involved in progression of GC and could be a new therapeutic target for this disease.

Trichostatin A attenuates ventilation-augmented epithelial-mesenchymal transition in mice with bleomycin-induced acute lung injury by suppressing the Akt pathway

Background

Mechanical ventilation (MV) used in patients with acute respiratory distress syndrome (ARDS) can cause diffuse lung inflammation, an effect termed ventilator-induced lung injury, which may produce profound pulmonary fibrogenesis. Histone deacetylases (HDACs) and serine/threonine kinase/protein kinase B (Akt) are crucial in modulating the epithelial–mesenchymal transition (EMT) during the reparative phase of ARDS; however, the mechanisms regulating the interactions among MV, EMT, HDACs, and Akt remain unclear. We hypothesized that trichostatin A (TSA), a HDAC inhibitor, can reduce MV-augmented bleomycin-induced EMT by inhibiting the HDAC4 and Akt pathways.

Methods

Five days after bleomycin treatment to mimic acute lung injury (ALI), wild-type or Akt-deficient C57BL/6 mice were exposed to low-tidal-volume (low-V_T, 6 mL/kg) or high-V_T (30 mL/kg) MV with room air for 5 h after receiving 2 mg/kg TSA. Nonventilated mice were examined as controls.

Results

Following bleomycin exposure in wild-type mice, high-V_T MV induced substantial increases in microvascular leaks; matrix metalloproteinase-9 (MMP-9) and plasminogen activator inhibitor-1 proteins; free radical production; Masson’s trichrome staining; fibronectin, MMP-9, and collagen 1a1 gene expression; EMT (identified by increased localized staining of α-smooth muscle actin and decreased staining of E-cadherin); total HDAC activity; and HDAC4 and Akt activation (P < 0.05). In Akt-deficient mice, the MV-augmented lung inflammation, profibrotic mediators, EMT profiles, Akt activation, and pathological fibrotic scores were reduced and pharmacologic inhibition of HDAC4 expression was triggered by TSA (P < 0.05).

Conclusions

Our data indicate that TSA treatment attenuates high-V_T MV-augmented EMT after bleomycin-induced ALI, in part by inhibiting the HDAC4 and Akt pathways.

Low vitamin D status is associated with advanced liver fibrosis in patients with nonalcoholic fatty liver disease

Several studies explored the association between vitamin D status and nonalcoholic fatty liver disease with contradictory results. We aimed to investigate the association between vitamin D status, inflammatory cytokines and liver fibrosis in nonalcoholic fatty liver disease patients. Two hundred nineteen nonalcoholic fatty liver disease patients and 166 age- and gender- matched healthy controls were recruited for this study. Serum 25(OH)D was measured by radioimmunoassay. Serum interleukin-8 and transforming growth factor-β1 were measured using ELISA. Serum 25(OH)D was only marginally decreased in nonalcoholic fatty liver disease patients. Interestingly, serum 25(OH)D was markedly reduced in nonalcoholic fatty liver disease patients with advanced liver fibrosis compared to nonalcoholic fatty liver disease patients with indeterminate liver fibrosis and no advanced fibrosis. Logistic regression analysis showed that there was an inverse association between serum 25(OH)D and severity of liver fibrosis in nonalcoholic fatty liver disease patients. Further analysis showed that serum interleukin-8 was elevated in nonalcoholic fatty liver disease patients, the highest interleukin-8 in patients with advanced fibrosis. An inverse correlation between serum 25(OH)D and interleukin-8 was observed in nonalcoholic fatty liver disease patients with and without liver fibrosis. Although serum transforming growth factor-β1 was slightly elevated in nonalcoholic fatty liver disease patients, serum transforming growth factor-β1 was reduced in nonalcoholic fatty liver disease patients with advanced fibrosis. Unexpectedly, a positive correlation between serum 25(OH)D and transforming growth factor-β1 was observed in nonalcoholic fatty liver disease patients with advanced fibrosis. In conclusion, low vitamin D status is associated with advanced liver fibrosis in nonalcoholic fatty liver disease patients. Interleukin-8 may be an important mediator for hepatic fibrosis in nonalcoholic fatty liver disease patients with low vitamin D status.

Calcitriol inhibits tumor necrosis factor alpha and macrophage inflammatory protein-2 during lipopolysaccharide-induced acute lung injury in mice

Acute lung injury is a common complication of sepsis in intensive care unit patients with an extremely high mortality. The present study investigated the effects of calcitriol, the active form of vitamin D, on tumor necrosis factor alpha (TNF-α) and macrophage inflammatory protein-2 (MIP-2) in sepsis-induced acute lung injury. Mice were intraperitoneally (i.p.) injected with lipopolysaccharide (LPS, 1.0mg/kg) to establish the animal model of sepsis-induced acute lung injury. Some mice were i.p. injected with calcitriol (1.0μg/kg) before LPS injection. An obvious infiltration of inflammatory cells in the lungs was observed beginning at 1h after LPS injection. Correspondingly, TNF-α and MIP-2 in sera and lung homogenates were markedly elevated in LPS-treated mice. Interestingly, calcitriol obviously alleviated LPS-induced infiltration of inflammatory cells in the lungs. Moreover, calcitriol markedly attenuated LPS-induced elevation of TNF-α and MIP-2 in sera and lung homogenates. Further analysis showed that calcitriol repressed LPS-induced p38 mitogen-activated protein kinase (MAPK) and protein kinase B (Akt) phosphorylation. In addition, calcitriol blocked LPS-induced nuclear translocation of nuclear factor kappa B (NF-κB) p65 and p50 subunit in the lungs. Taken together, these results suggest that calcitriol inhibits inflammatory cytokines production in LPS-induced acute lung injury.