Development of lung tissue models and their applications

The lungs are important organs that play a critical role in the development of specific diseases, as well as responding to the effects of drugs, chemicals, and environmental pollutants. Due to the ethical concerns around animal testing, alternative methods have been sought which are more time-effective, do not pose ethical issues for animals, do not involve species differences, and provide easy investigation of the pathobiology of lung diseases. Several national and international organizations are working to accelerate the development and implementation of structurally and functionally complex tissue models as alternatives to animal testing, particularly for the lung. Unfortunately, to date, there is no lung tissue model that has been accepted by regulatory agencies for use in inhalation toxicology. This review discusses the challenges involved in developing a relevant lung tissue model derived from human cells such as cell lines, primary cells, and pluripotent stem cells. It also introduces examples of two-dimensional (2D) air-liquid interface and monocultured and co-cultured three-dimensional (3D) culture techniques, particularly organoid culture and 3D bioprinting. Furthermore, it reviews development of the lung-on-a-chip model to mimic the microenvironment and physiological performance. The applications of lung tissue models in various studies, especially disease modeling, viral respiratory infection, and environmental toxicology will be also introduced. The development of a relevant lung tissue model is extremely important for standardizing and validation the in vitro models for inhalation toxicity and other studies in the future.

Preventive effects of Ramelteon on bleomycin-induced pulmonary fibrosis in mice

Pulmonary fibrosis (PF) is a devastating lung disease that leads to impaired lung function and ultimately death. Several studies have suggested that melatonin, a hormone involved in regulating sleep-wake cycles, may be effective in improving PF. Ramelteon, an FDA-approved melatonin receptor agonist, has shown promise in exerting an anti-PF effect similar to melatonin. However, further investigations are required for illuminating the extent on its therapeutic benefits and the underlying molecular mechanisms. In this work, a mouse lung fibrosis model was built through intratracheal administration of bleomycin (BLM). Subsequently, the mice were administrated Ramelteon for a duration of 3 weeks to explore its efficacy and mechanism of action. Additionally, we utilized a TGF-β1-induced MRC-5 cell model to further investigate the molecular mechanism underlying ramelteon's effects. Functionally, Ramelteon partially abrogated TGF-β1-induced pulmonary fibrosis and reduced fibroblast proliferation, extracellular matrix deposition, and differentiation into myofibroblasts. In vivo experiments, ramelteon attenuated BLM-induced pulmonary fibrosis and collagen deposition. Mechanistically, ramelteon exerts its beneficial effect by alleviating translocation and expression of YAP1, a core component of Hippo pathway, from cytoplasm to nucleus; however, overexpression of YAP1 reversed this effect. In conclusion, our findings indicate that ramelteon can improve PF by regulating Hippo pathway and may become a potential candidate as a therapy to PF.

METTL3-mediated m6A RNA methylation induces the differentiation of lung resident mesenchymal stem cells into myofibroblasts via the miR-21/PTEN pathway

BACKGROUND

The accumulation of myofibroblasts is the key pathological feature of pulmonary fibrosis (PF). Aberrant differentiation of lung-resident mesenchymal stem cells (LR-MSCs) has been identified as a critical source of myofibroblasts, but the molecular mechanisms underlying this process remain largely unknown. In recent years, N6-methyladenosine (m6A) RNA modification has been implicated in fibrosis development across diverse organs; however, its specific role in promoting the differentiation of LR-MSCs into myofibroblasts in PF is not well defined.

METHODS

In this study, we examined the levels of m6A RNA methylation and the expression of its regulatory enzymes in both TGF-β1-treated LR-MSCs and fibrotic mouse lung tissues. The downstream target genes of m6A and their related pathways were identified according to a literature review, bioinformatic analysis and experimental verification. We also assessed the expression levels of myofibroblast markers in treated LR-MSCs and confirmed the involvement of the above-described pathway in the aberrant differentiation direction of LR-MSCs under TGF-β1 stimulation by overexpressing or knocking down key genes within the pathway.

RESULTS

Our results revealed that METTL3-mediated m6A RNA methylation was significantly upregulated in both TGF-β1-treated LR-MSCs and fibrotic mouse lung tissues. This process directly led to the aberrant differentiation of LR-MSCs into myofibroblasts by targeting the miR-21/PTEN pathway. Moreover, inhibition of METTL3 or miR-21 and overexpression of PTEN could rescue this abnormal differentiation.

CONCLUSION

Our study demonstrated that m6A RNA methylation induced aberrant LR-MSC differentiation into myofibroblasts via the METTL3/miR-21/PTEN signaling pathway. We indicated a novel mechanism to promote PF progression. Targeting METTL3-mediated m6A RNA methylation and its downstream targets may present innovative therapeutic approaches for the prevention and treatment of PF.

Post-COVID-19 Pulmonary Fibrosis: Facts-Challenges and Futures: A Narrative Review

Patients with coronavirus disease 2019 (COVID-19) usually suffer from post-acute sequelae of coronavirus disease 2019 (PASC). Pulmonary fibrosis (PF) has the most significant long-term impact on patients' respiratory health, called post-COVID-19 pulmonary fibrosis (PC19-PF). PC19- PF can be caused by acute respiratory distress syndrome (ARDS) or pneumonia due to COVID-19. The risk factors of PC19-PF, such as older age, chronic comorbidities, the use of mechanical ventilation during the acute phase, and female sex, should be considered. Individuals with COVID-19 pneumonia symptoms lasting at least 12 weeks following diagnosis, including cough, dyspnea, exertional dyspnea, and poor saturation, accounted for nearly all disease occurrences. PC19-PF is characterized by persistent fibrotic tomographic sequelae associated with functional impairment throughout follow-up. Thus, clinical examination, radiology, pulmonary function tests, and pathological findings should be done to diagnose PC19-PF patients. PFT indicated persistent limitations in diffusion capacity and restrictive physiology, despite the absence of previous testing and inconsistency in the timeliness of assessments following acute illness. It has been hypothesized that PC19-PF patients may benefit from idiopathic pulmonary fibrosis treatment to prevent continued infection-related disorders, enhance the healing phase, and manage fibroproliferative processes. Immunomodulatory agents might reduce inflammation and the length of mechanical ventilation during the acute phase of COVID-19 infection, and the risk of the PC19-PF stage. Pulmonary rehabilitation, incorporating exercise training, physical education, and behavioral modifications, can improve the physical and psychological conditions of patients with PC19-PF.

The MIR155 host gene/microRNA-627/HMGB1/NF-κB loop modulates fibroblast proliferation and extracellular matrix deposition

Pulmonary fibrosis (PF), which is characterized by excessive matrix formation, may ultimately lead to irreversible lung damage and thus death. Fibroblast activation has been regarded as a central event during PF pathogenesis. In our previous study, we confirmed that the miR-627/high-mobility group box protein 1 (HMGB1)/Nuclear factor kappa beta (NF-κB) axis modulates transforming growth factor beta 1 (TGFβ1)-induced pulmonary fibrosis. In the present study, we investigated the upstream factors leading to miR-627 dysregulation in the process of pulmonary fibroblast activation and PF. The lncRNA MIR155 host gene (MIR155HG) was found to be abnormally upregulated in pulmonary fibrosis tissues and TGFβ1-stimulated normal human primary lung fibroblasts (NHLFs). By directly binding to miR-627, MIR155HG inhibited miR-627 expression. MIR155HG overexpression enhanced TGFβ1-induced increases in HMGB1 protein expression and p65 phosphorylation, NHLF proliferation, and extracellular matrix (ECM) deposition. In contrast, miR-627 overexpression attenuated the TGFβ1-induced changes in NHLFs and significantly reversed the effects of MIR155HG overexpression. Under TGFβ1 stimulation, miR-627 inhibition promoted, whereas JSH-23 treatment inhibited NF-κB activation; in NHLFs, NF-κB overexpression upregulated, whereas JSH-23 treatment downregulated MIR155HG expression. In tissue samples, HMGB1 protein levels and p65 phosphorylation were increased; MIR155HG was negatively correlated with miR-627 and positively correlated with HMGB1. In conclusion, we validated that the MIR155HG/miR-627/HMGB1/NF-κB axis formed a regulatory loop that modulates TGFβ1-induced NHLF activation. Considering the critical role of NHLF activation in PF pathogenesis, the NF-κB/MIR155HG/miR-627/HMGB1 regulatory loop could exert a vital effect on PF pathogenesis. Further in vivo and clinical investigations are required to confirm this model.

Acute Lung Injury: IL-17A-Mediated Inflammatory Pathway and Its Regulation by Curcumin

Acute lung injury (ALI) is characterized by acute inflammation and tissue injury results in dysfunction of the alveolar epithelial membrane. If the epithelial injury is severe, a fibroproliferative phase of ALI can develop. During this phase, the activated fibroblast and myofibroblasts synthesize excessive collagenous extracellular matrix that leads to a condition called pulmonary fibrosis. Lung injury can be caused by several ways; however, the present review focus on bleomycin (BLM)-mediated changes in the pathology of lungs. BLM is a chemotherapeutic agent and has toxic effects on lungs, which leads to oxidative damage and elaboration of inflammatory cytokines. In response to the injury, the inflammatory cytokines will be activated to defend the system from injury. These cytokines along with growth factors stimulate the proliferation of myofibroblasts and secretion of pathologic extracellular matrix. During BLM injury, the pro-inflammatory cytokine such as IL-17A will be up-regulated and mediates the inflammation in the alveolar epithelial cell and also brings about recruitment of certain inflammatory cells in the alveolar surface. These cytokines probably help in up-regulating the expression of p53 and fibrinolytic system molecules during the alveolar epithelial cells apoptosis. Here, our key concern is to provide the adequate knowledge about IL-17A-mediated p53 fibrinolytic system and their pathogenic progression to pulmonary fibrosis. The present review focuses mainly on IL-17A-mediated p53-fibrinolytic aspects and how curcumin is involved in the regulation of pathogenic progression of ALI and pulmonary fibrosis.

Hydrogen Peroxide Preconditioning Promotes Protective Effects of Umbilical Cord Vein Mesenchymal Stem Cells in Experimental Pulmonary Fibrosis

Purpose: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disorder with few available treatments. Mesenchymal stem cell therapy (MSCT), an innovative approach, has high therapeutic potential when used to treat IPF. According to recent data, preconditioning of MSCs can improve their therapeutic effects. Our research focuses on investigating the anti-inflammatory and antifibrotic effects of H2 O2 -preconditioned MSCs (p-MSCs) on mice with bleomycin-induced pulmonary fibrosis (PF). Methods: Eight-week-old male C57BL/6 mice were induced with PF by intratracheal (IT) instillation of bleomycin (4 U/kg). Human umbilical cord vein-derived MSCs (hUCV-MSCs) were isolated and exposed to a sub-lethal concentration (15 μM for 24 h) of H2 O2 in vitro. One week following the injection of bleomycin, 2×105 MSCs or p-MSCs were injected (IT) into the experimental PF. The survival rate and weight of mice were recorded, and 14 days after MSCs injection, all mice were sacrificed. Lung tissue was removed from these mice to examine the myeloperoxidase (MPO) activity, histopathological changes (hematoxylin-eosin and Masson's trichrome) and expression of transforming growth factor beta 1 (TGF-β1) and alpha-smooth muscle actin (α-SMA) through immunohistochemistry (IHC) staining. Results: Compared to the PF+MSC group, p-MSCs transplantation results in significantly decreased connective tissue (P<0.05) and collagen deposition. Additionally, it is determined that lung tissue in the PF+pMSC group has increased alveolar space (P<0.05) and diminished expression of TGF-β1 and α-SMA. Conclusion: The results demonstrate that MSCT using p-MSCs decreases inflammatory and fibrotic factors in bleomycin-induced PF, while also able to increase the therapeutic potency of MSCT in IPF.

An animal research and a chemical composition analysis of a Chinese prescription for pulmonary fibrosis: Yangfei Huoxue Decoction

ETHNOPHARMACOLOGICAL EVIDENCE

Pulmonary fibrosis (PF) is a progressive disease characterized by the aberrant accumulation of fibrotic tissue in the lungs parenchyma, associated with significant morbidity. Few effective drugs have been developed to reverse PF or even halt the disease progression. Yangfei Huoxue Decoction (YHD), a Traditional Chinese Medicine, which consisted of Astragalus membranacus(AM), Glehnia littoralis(GL), Schisandra chinensis(SC), Salvia miltiorrhiza Bunge(SB), Reynoutria japonica(RJ), Ligusticum chuanxiong(LX), and Euonymus alatus(EA) , has been used in China for the treatment of PF for many years with remarkable efficacy. According to the clinic observation of the results, we conducted experiments on animals, the process of BLM-induced pulmonary fibrosis in rats was interfered by YHD, through the detection of pulmonary fibrosis rats' blood cells and plasma, we selected the related molecules that may exert proinflammatory(IL-1β), promote angiogenesis(vascular endothelial growth factor ,VEGF). For further explicitly research, we should know what the chemical composition the prescription (YHD) contains and what the related bioactive components have. In accordance with in-house library and evaluating the characteristic MS fragmentation patterns, the schisandra chinensis methanol, lignin, flavonol, polyphenol, tanshinone, salvianolic acid, anthraquinone, ligustrazine, etc. had a retardant and inhibitory effect on the development and formation of pulmonary fibrosis. These results will aid in the quality control of YHD, as well as provide fundamental data for further pharmaco-mechanisms studies.

AIM OF THE STUDY

To discover the pulmonary immune related bioactive components of YHD.

MATERIALS AND METHODS

Animal Experiment:144 SD rats, based on the principles of randomization divided into eight groups, Control group, bleomycin(BLM) group, BLM + dexamethasone(BLM + DXM) group, BLM + Yangfei(YF) group, BLM + Huoxue(HX) group, BLM + high-doseYHD(YHD-H) group, BLM + medium-doseYHD(YHD-M) group, and BLM + low-doseYHD(YHD-L) group, each group of 18 rats. After endotracheal administration of Bleomycin by tracheotomy, rats were sacrificed on day 7, day 14 and day 28, blood and plasma were taken at the same time. Respectively, the VEGF, an immune molecule associated with angiogenesis, and IL-1β in plasma were detected by ELISA at three time periods. Component testing: 100 g YHD were constituted of SB 15 g, LX 12 g, EA 10 g, RJ 15 g, AM 20 g, GL 20 g and SC 8 g. All herbs were obtained from Beijing Tong Ren Tang (Group) Co ltd. The voucher specimens were identified by Prof. Jiening Gong (Nanjing University of Chinese Medicine). YHD were extracted by sonication with 1 L ethanol/water (70:30, v/v) for two cycle (1 h per cycle) at room temperature. The combined extracts were filtered, condensed, and reconstituted with 50 mL methanol before analysis. Standard Cianidanol, Ferulic Acid, Polydatin, Calycosin 7-O-glucoside, Tanshinone IIA, Salvianolic acid B, Schizandrol A, and Isoimperatorin were prepared in methanol. After centrifuging at 20,000 rpm for 10 min, 4 μL supernatant was injected into the Ultra-Performance Liquid Chromatography coupled with Quadrupole Time-of-Flight tandem mass spectrometry (UPLC/QTOF-MS^E) combined with UNIFI informatics platform for analysis.

CONCLUSION

The experiment results revealed that the vascularized VEGF, inflammatory factor expression of IL-1β was restrained by YHD. The UPLC/QTOF-MS^E method, an automatic database screening platform and the characteristic MS fragmentation patterns have efficiently facilitated the post data process, so we test for the identification of major components in YHD by this technology, more than seven or more active ingredients, the results showed that YHD contained a total of 55 components, including 11 lignans, 12 flavonoids, 7 tanshinones, 9 organic acid, 5 polyphenols, 4 anthraquinones, 5 senkyunolides and 2 others. Based on this, we can ensure the discovery and analysis of biologically active compounds in YHD, as well as provide a reference for the quality evaluation. We expect the method presented here could be applied to other multi-component TCM formula. In addition, we can conduct more in-depth research, such as mechanism research, molecular detection, gene target and so on.

MicroRNA-30d/JAG1 axis modulates pulmonary fibrosis through Notch signaling pathway

Pulmonary fibrosis (PF) is a fibroproliferative disease which can finally end up fatal lung failure. PF is characterized by abnormal proliferation of fibroblast, dysregulated fibroblast differentiation to myofibroblast and disorganized collagen and extracellular matrix (ECM) production, deposition and degradation. JAG1/Notch signaling has been reported to play a key role in tissue fibrosis including PF. Herein, we confirmed the abnormal upregulation of JAG1 mRNA expression and protein levels in PF tissue specimens; JAG1 knockdown reduced TGF-β1-induced α-SMA and Collagen I protein levels. From the aspect of miRNA regulation, we searched for candidate miRNAs which might target JAG1 to inhibit its expression. Among the selected miRNAs, miR-30d expression was downregulated in PF tissues; miR-30d overexpression attenuated TGF-β1-induced primary normal human lung fibroblast (NHLF) proliferation, as well as α-SMA and Collagen I protein levels. Through directly binding to the 3'-UTR of JAG1, miR-30d significantly inhibited JAG1 mRNA expression and protein level. Furthermore, JAG1 overexpression partially reversed the effect of miR-30d on NHLF proliferation and α-SMA and Collagen I proteins upon TGF-β1 stimulation; miR-30d could suppress TGF-β1 function on NHLFs through blocking JAG1/Notch signaling. Rescuing miR-30d expression to suppress TGF-β1-induced activation of JAG1/Notch signaling may present a promising strategy for PF treatment.