Mdka produced by the activated HSCs drives bipotential progenitor cell redifferentiation during zebrafish biliary-mediated liver regeneration.

BACKGROUND AND AIMS: After extensive hepatocyte loss or impaired hepatocyte proliferation, liver regeneration occurs through trans-differentiation of biliary epithelial cells (BECs), which involves dedifferentiation of biliary epithelial cells into bipotential progenitor cells (BP-PCs) and subsequent redifferentiation of BP-PCs into nascent hepatocytes and biliary epithelial cells. Despite several studies on the redifferentiation process of BP-PCs into nascent hepatocytes, the contributions of nonparenchymal cells in this process remain poorly understood. APPROACH AND RESULTS: Using the zebrafish severe liver injury model, we observed specific expression of midkine a (Mdka) in the activated HSCs through single-cell analyses and fluorescence in situ hybridization. Genetic mutation, pharmacological inhibition, whole-mount in situ hybridizations, and antibody staining demonstrated an essential role of mdka in the redifferentiation of BP-PCs during liver regeneration. Notably, we identified Nucleolin (Ncl), the potential receptor for Mdka, specifically expressed in BP-PCs, and its mutant recapitulated the mdka mutant phenotypes with impaired BP-PC redifferentiation. Mechanistically, the Mdka-Ncl axis drove Erk1 activation in BP-PCs during liver regeneration. Furthermore, overexpression of activated Erk1 partially rescued the defective liver regeneration in the mdka mutant. CONCLUSIONS: The activated HSCs produce Mdka to drive the redifferentiation process of BP-PCs through activating Erk1 during the biliary-mediated liver regeneration, implying previously unappreciated contributions of nonparenchymal cells to this regeneration process.

The oncogenic kinase TOPK upregulates in psoriatic keratinocytes and contributes to psoriasis progression by regulating neutrophils infiltration.

BACKGROUND: T-LAK cell-oriented protein kinase (TOPK) strongly promotes the malignant proliferation of cancer cells and is recognized as a promising biomarker of tumor progression. Psoriasis is a common inflammatory skin disease featured by excessive proliferation of keratinocytes. Although we have previously reported that topically inhibiting TOPK suppressed psoriatic manifestations in psoriasis-like model mice, the exact role of TOPK in psoriatic inflammation and the underlying mechanism remains elusive. METHODS: GEO datasets were analyzed to investigate the association of TOPK with psoriasis. Skin immunohistochemical (IHC) staining was performed to clarify the major cells expressing TOPK. TOPK conditional knockout (cko) mice were used to investigate the role of TOPK-specific deletion in IMQ-induced psoriasis-like dermatitis in mice. Flow cytometry was used to analyze the alteration of psoriasis-related immune cells in the lesional skin. Next, the M5-induced psoriasis cell model was used to identify the potential mechanism by RNA-seq, RT-RCR, and western blotting. Finally, the neutrophil-neutralizing antibody was used to confirm the relationship between TOPK and neutrophils in psoriasis-like dermatitis in mice. RESULTS: We found that TOPK levels were strongly associated with the progression of psoriasis. TOPK was predominantly increased in the epidermal keratinocytes of psoriatic lesions, and conditional knockout of TOPK in keratinocytes suppressed neutrophils infiltration and attenuated psoriatic inflammation. Neutrophils deletion by neutralizing antibody greatly diminished the suppressive effect of TOPK cko in psoriasis-like dermatitis in mice. In addition, topical application of TOPK inhibitor OTS514 effectively attenuated already-established psoriasis-like dermatitis in mice. Mechanismly, RNA-seq revealed that TOPK regulated the expression of some genes in the IL-17 signaling pathway, such as neutrophils chemokines CXCL1, CXCL2, and CXCL8. TOPK modulated the expression of neutrophils chemokines via activating transcription factors STAT3 and NF-κB p65 in keratinocytes, thereby promoting neutrophils infiltration and psoriasis progression. CONCLUSIONS: This study identified a crucial role of TOPK in psoriasis by regulating neutrophils infiltration, providing new insights into the pathogenesis of psoriasis.

Synthesis and evaluation of L-quebrachitol derivatives against platelet aggregation.

Thrombosis plays an important role in the occurrence and development of cardiovascular and cerebrovascular diseases that contribute to high mortality and morbidity in patients. L-(-)-Quebrachitol (QCT), a natural product, was first isolated from quebracho bark. It can inhibit PAF receptor and decrease gastric damage induced by indomethacin, as a drug against platelet aggregation. Here, five QCT derivatives were synthesized and investigated for their inhibitory effects on platelet aggregation. Among them, compound 3a showed anticoagulant effects comparable to aspirin, while compound 4b showed dose-independent inhibitory activities in rats that were stronger than aspirin.

Farnesoid X Receptor Is Required for the Redifferentiation of Bipotential Progenitor Cells During Biliary-Mediated Zebrafish Liver Regeneration.

BACKGROUND AND AIMS: Liver regeneration after extreme hepatocyte loss occurs through transdifferentiation of biliary epithelial cells (BECs), which includes dedifferentiation of BECs into bipotential progenitor cells (BPPCs) and subsequent redifferentiation into nascent hepatocytes and BECs. Although multiple molecules and signaling pathways have been implicated to play roles in the BEC-mediated liver regeneration, mechanisms underlying the dedifferentiation-redifferentiation transition and the early phase of BPPC redifferentiation that is pivotal for both hepatocyte and BEC directions remain largely unknown. APPROACH AND RESULTS: The zebrafish extreme liver damage model, genetic mutation, pharmacological inhibition, transgenic lines, whole-mount and fluorescent in situ hybridizations and antibody staining, single-cell RNA sequencing, quantitative real-time PCR, and heat shock-inducible overexpression were used to investigate roles and mechanisms of farnesoid X receptor (FXR; encoded by nuclear receptor subfamily 1, group H, member 4 [nr1h4]) in regulating BPPC redifferentiation. The nr1h4 expression was significantly up-regulated in response to extreme liver injury. Genetic mutation or pharmacological inhibition of FXR was ineffective to BEC-to-BPPC dedifferentiation but blocked the redifferentiation of BPPCs to both hepatocytes and BECs, leading to accumulation of undifferentiated or less-differentiated BPPCs. Mechanistically, induced overexpression of extracellular signal-related kinase (ERK) 1 (encoded by mitogen-activated protein kinase 3) rescued the defective BPPC-to-hepatocyte redifferentiation in the nr1h4 mutant, and ERK1 itself was necessary for the BPPC-to-hepatocyte redifferentiation. The Notch activities in the regenerating liver of nr1h4 mutant attenuated, and induced Notch activation rescued the defective BPPC-to-BEC redifferentiation in the nr1h4 mutant. CONCLUSIONS: FXR regulates BPPC-to-hepatocyte and BPPC-to-BEC redifferentiations through ERK1 and Notch, respectively. Given recent applications of FXR agonists in the clinical trials for liver diseases, this study proposes potential underpinning mechanisms by characterizing roles of FXR in the stimulation of dedifferentiation-redifferentiation transition and BPPC redifferentiation.

Effect of local coordination on catalytic activities and selectivities of Fe-based catalysts for N2 reduction.

Electrochemical reduction of nitrogen is considered a promising route for achieving green and sustainable ammonia synthesis under ambient conditions. A transition metal atom loaded on N-doped graphene is commonly used in the nitrogen reduction reaction (NRR), but the effect of the graphene's coordination environment on electron transfer has rarely been studied. Herein, the NRR performance of Fe1/2/3 clusters, anchored on single-vacancy and N-doped graphene, is investigated systematically via density functional theory (DFT). The calculation results show that the Fe2 cluster supported by two N atom-modified single-vacancy graphene displays the highest catalytic performance of NRR with the lowest energy barrier of 0.62 eV among the 12 candidates, and exhibits efficient selectivity. It has superior performance because of the highly asymmetrical distribution of electrons on graphene, the large positive charge of the Fe2, and the strong adsorption of *NNH. This study provides a new strategy to improve the NRR performance by regulating the Fe1/2/3 clusters coordination environment.

Inversion of spectral information obtained during hypersonic impact.

A large number of space activities are generating a high amount of undesirable space debris, which causes inevitable damage to spacecraft and satellites. Moreover, the damage assessment of ultrahigh-speed debris is a challenging task that requires both theoretical and ground-level experimental simulations. One should note that the location and damage degree can be preliminarily determined by measuring the impact flash spectrum, which provides basic data for damage assessment. Herein, the radiation spectrum of an ultrahigh-speed collision between plastic projectile and aluminum target is measured by using spectroscopic technology. The surface temperature of the colliding material, electron temperature, and electron density in the plasma are simultaneously retrieved by using a single-frame spectrum. The single-frame spectrum is separated into a continuous spectrum and a line spectrum by using continuous thermal radiation spectrum inversion material interface temperature and line spectrum inversion electron temperature and electron density in the plasma.

Antibody Detection and Dynamic Characteristics in Patients With Coronavirus Disease 2019.

BACKGROUND: The coronavirus disease 2019 (COVID-19), caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been rapidly spreading nationwide and abroad. A serologic test to identify antibody dynamics and response to SARS-CoV-2 was developed. METHODS: The antibodies against SARS-CoV-2 were detected by an enzyme-linked immunosorbent assay based on the recombinant nucleocapsid protein of SARS-CoV-2 in patients with confirmed or suspected COVID-19 at 3-40 days after symptom onset. The gold standard for COVID-19 diagnosis was nucleic acid testing for SARS-CoV-2 by real-time reverse-transcription polymerase chain reaction (rRT-PCR). The serodiagnostic power of the specific immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against SARS-CoV-2 was investigated in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and consistency rate. RESULTS: The seroconversion of specific IgM and IgG antibodies were observed as early as the fourth day after symptom onset. In the patients with confirmed COVID-19, sensitivity, specificity, PPV, NPV, and consistency rate of IgM were 77.3% (51/66), 100%, 100%, 80.0%, and 88.1%, respectively, and those of IgG were 83.3% (55/66), 95.0%, 94.8%, 83.8%, and 88.9%. In patients with suspected COVID-19, sensitivity, specificity, PPV, NPV, and consistency rate of IgM were 87.5% (21/24), 100%, 100%, 95.2%, and 96.4%, respectively, and those of IgG were 70.8% (17/24), 96.6%, 85.0%, 89.1%, and 88.1%. Both antibodies performed well in serodiagnosis for COVID-19 and rely on great specificity. CONCLUSIONS: The antibodies against SARS-CoV-2 can be detected in the middle and later stages of the illness. Antibody detection may play an important role in the diagnosis of COVID-19 as a complementary approach to viral nucleic acid assays.

Mammalian Target of Rapamycin Complex 1 Signaling Is Required for the Dedifferentiation From Biliary Cell to Bipotential Progenitor Cell in Zebrafish Liver Regeneration.

The liver has a high regenerative capacity. Upon two-thirds partial hepatectomy, the hepatocytes proliferate and contribute to liver regeneration. After severe liver injury, when the proliferation of residual hepatocytes is blocked, the biliary epithelial cells (BECs) lose their morphology and express hepatoblast and endoderm markers, dedifferentiate into bipotential progenitor cells (BP-PCs), then proliferate and redifferentiate into mature hepatocytes. Little is known about the mechanisms involved in the formation of BP-PCs after extreme liver injury. Using a zebrafish liver extreme injury model, we found that mammalian target of rapamycin complex 1 (mTORC1) signaling regulated dedifferentiation of BECs and proliferation of BP-PCs. mTORC1 signaling was up-regulated in BECs during extreme hepatocyte ablation and continuously expressed in later liver regeneration. Inhibition of mTORC1 by early chemical treatment before hepatocyte ablation blocked the dedifferentiation from BECs into BP-PCs. Late mTORC1 inhibition after liver injury reduced the proliferation of BP-PC-derived hepatocytes and BECs but did not affect BP-PC redifferentiation. mTOR and raptor mutants exhibited defects in BEC transdifferentiation including dedifferentiation, BP-PC proliferation, and redifferentiation, similar to the chemical inhibition. Conclusion: mTORC1 signaling governs BEC-driven liver regeneration by regulating the dedifferentiation of BECs and the proliferation of BP-PC-derived hepatocytes and BECs.

A comparison study of SARS-CoV-2 IgG antibody between male and female COVID-19 patients: A possible reason underlying different outcome between sex.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in China at the end of 2019 has spread throughout the world and caused many thousands of deaths. The previous study reported a higher severe status rate and mortality rate in male patients in China. However, the reason underlying this difference has not been reported. The convalescent plasma containing a high level of SARS-CoV-2 immunoglobulin G (IgG) antibody has been used in clinical therapy and achieved good effects in China. In this study, to compare the differences of the SARS-CoV-2 IgG antibody between male and female patients, a total number of 331 patients confirmed SARS-CoV-2 infection were enrolled. The serum of these patients was collected during hospitalization and detected for the SARS-CoV-2 IgG antibody. Our data showed that the concentration of IgG antibody in mild, general, and recovering patients showed no difference between male and female patients. In severe status, compared with male patients, there were more female patients having a relatively high concentration of serum SARS-CoV-2 IgG antibody. In addition, the generation of IgG antibody in female patients was stronger than male patients in disease early phase. Our study identified a discrepancy in the SARS-CoV-2 IgG antibody level in male and female patients, which may be a potential cause leading to a different outcome of Coronavirus Disease 2019 between sex.

COVID-19 confirmed patients with negative antibodies results.

BACKGROUND: A new coronavirus disease 2019 (COVID-19) has escalated to a pandemic since its first outbreak in Wuhan, China. A small proportion of patients may have difficulty in generating IgM or IgG antibodies against SARS-CoV-2, and little attention has been paid to them. CASE PRESENTATIONS: We present two cases of confirmed COVID-19 patients and characterize their initial symptoms, chest CT results, medication, and laboratory test results in detail (including RT-PCR, IgM/ IgG, cytokine and blood cell counts). CONCLUSION: Both of patients with confirmed COVID-19 pneumonia failed to produce either IgM or IgG even 40 to 50 days after their symptoms onset. This work provides evidence demonstrating that at least a small proportion of patients may have difficulty in rapidly gaining immunity against SARS-CoV-2.

Inversion of target radiant temperature and distance via spectrum separation.

Accurate measurement of temperature and distance is essential for applications in multiple fields such as air defense, antimissile systems, laser damage, and infrared remote sensing. However, ranging currently relies on either laser or infrared radiation characteristics, neither of which fully utilize the substantial information contained in the spectrum. In this study, we realized the simultaneous inversion of target radiant temperature and distance via spectrum separation based on the distance information from the atmospheric spectrum as well as the temperature information from multispectral radiation thermometry (MRT), by measuring the thermal radiation spectrum of distant high-temperature objects. The study initially involved conducting a theoretical analysis of long-distance MRT in the atmosphere by utilizing the least squares and Newton's iteration methods. Once the thermal radiation spectrum and the long-distance atmospheric spectral transmittance were acquired from nonlinear models, highly precise and accurate radiant temperature and distance information was derived via simultaneous inversion. Subsequently, experimental verifications were performed to measure an explosion spectrum at a temperature of approximately 2000 K and a distance of 9 km. The spectral band was 400-900 nm, and the temperature and distance of the explosion calculated by the inversion was 2004.4 K and 9.9 km, respectively. The inversion distance error was 10%, indicating that the simultaneous inversion of radiant temperature and distance was successful and that the proposed method was effective. The method proposed in this study can be applied to the measurement of radiant temperature and distance of long-distance objects.

Ribosome biogenesis protein Urb2 regulates hematopoietic stem cells development via P53 pathway in zebrafish.

Ribosome biogenesis is a significant process in cells. Dysfunction in this process will result in the defects of protein synthesis and consequently cause the development of specific diseases called ribosomopathies. Mutations in ribosome biogenesis protein Rps19, Rpl5, or Rpl11 can lead to hematopoietic defects in human, thus triggering the disease Diamond Blackfan anemia. However, the regulatory mechanisms of ribosome biogenesis in hematopoiesis remain incompletely understood. In this study, we describe a zebrafish mutant cq42, which carries a nonsense mutation in the gene that encodes ribosome biogenesis 2 homolog (Urb2). Urb2 is strongly expressed in the caudal hematopoietic tissue (CHT) during hematopoietic stem cells (HSCs) expanding. Molecular characterization of urb2cq42 larvae suggest that urb2 deficiency notably decrease the population of HSCs in CHT and early T cells in thymus. Further analysis shows that compromised cell proliferation and superfluous apoptosis are observed in the CHT of urb2cq42 mutant. P53 pathway is upregulated in the urb2cq42 larvae and loss-of-function of P53 can fully rescue the hematopoietic defects in urb2cq42 mutant. These data demonstrate that urb2 is essential for HSCs development through the regulation of P53 pathway.

miR-18a-5p Inhibits Sub-pleural Pulmonary Fibrosis by Targeting TGF-ß Receptor II.

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease that typically leads to respiratory failure and death within 3-5 years of diagnosis. Sub-pleural pulmonary fibrosis is a pathological hallmark of IPF. Bleomycin treatment of mice is a an established pulmonary fibrosis model. We recently showed that bleomycin-induced epithelial-mesenchymal transition (EMT) contributes to pleural mesothelial cell (PMC) migration and sub-pleural pulmonary fibrosis. MicroRNA (miRNA) expression has recently been implicated in the pathogenesis of IPF. However, changes in miRNA expression in PMCs and sub-pleural fibrosis have not been reported. Using cultured PMCs and a pulmonary fibrosis animal model, we found that miR-18a-5p was reduced in PMCs treated with bleomycin and that downregulation of miR-18a-5p contributed to EMT of PMCs. Furthermore, we determined that miR-18a-5p binds to the 3' UTR region of transforming growth factor ß receptor II (TGF-ßRII) mRNA, and this is associated with reduced TGF-ßRII expression and suppression of TGF-ß-Smad2/3 signaling. Overexpression of miR-18a-5p prevented bleomycin-induced EMT of PMC and inhibited bleomycin-induced sub-pleural fibrosis in mice. Taken together, our data indicate that downregulated miR-18a-5p mediates sub-pleural pulmonary fibrosis through upregulation of its target, TGF-ßRII, and that overexpression of miR-18a-5p might therefore provide a novel approach to the treatment of IPF.

BMP4 inhibits PDGF-induced proliferation and collagen synthesis via PKA-mediated inhibition of calpain-2 in pulmonary artery smooth muscle cells.

In the present study, we investigated the effect of bone morphogenetic protein 4 (BMP4) on PDGF-induced cell proliferation and collagen synthesis in pulmonary artery smooth muscle cells (PASMCs). Normal human PASMCs were incubated with and without PDGF-BB in the absence and presence of BMP4 for 0.5 to 24 h. The protein levels of collagen-I, p-Smad2/3, p-Smad1/5, and intracellular active TGF-ß1, calpain activity, and cell proliferation were then measured. The results showed that BMP4 induced an increase in p-Smad1/5 but had no effect on the protein levels of collagen-I, p-Smad2/3, and intracellular active TGF-ß1 and calpain activity in control PASMCs. Nevertheless, BMP4 attenuated increases in cell proliferation and protein levels of collagen-I, p-Smad2/3, and intracellular active TGF-ß1 and calpain activity in PASMCs exposed to PDGF-BB. Moreover, BMP4 increased PKA activity and inhibition of PKA prevented the inhibitory effects of BMP4 on PDGF-BB-induced calpain activation in normal PASMCs. The PKA activator forskolin recapitulated the suppressive effect of BMP4 on PDGF-induced calpain activation. Furthermore, BMP4 prevented a PDGF-induced decrease in calpain-2 phosphorylation at serine-369 in normal PASMCs. Finally, BMP4 did not attenuate PDGF-induced increases in cell proliferation, collagen-I protein levels, and calpain activation and did not induce PKA activation and did not prevent a PDGF-induced decrease in calpain-2 phosphorylation at serine-369 in PASMCs from idiopathic pulmonary arterial hypertension (PAH) patients. These data demonstrate that BMP4 inhibits PDGF-induced cell proliferation and collagen synthesis via PKA-mediated inhibition of calpain-2 in normal PASMCs. The inhibitory effects of BMP4 on PDGF-induced cell proliferation, collagen synthesis, and calpain-2 activation are impaired in PASMCs from PAH patients, which may contribute to pulmonary vascular remodeling in PAH.

Combined blockade of Tim-3 and MEK inhibitor enhances the efficacy against melanoma.

Insights into the role of the mitogen-activated protein kinase (MAPK) pathway and immune checkpoints have led combined targeted therapy and immunotherapy to be a promising regimen. Trametinib, as a mitogen-activated extracellular signal-regulated kinase (MEK) inhibitor, has demonstrated effectiveness in patients with advanced melanoma. T cell immunoglobulin- and mucin-domain-containing molecule-3 (Tim-3), an immune checkpoint molecule, participates in multiple negative regulation of antitumor immunity. We for the first time to our knowledge reported the combination of trametinib and anti-Tim-3 monoclonal antibody (mAb) in treating B16-F10 melanoma mice. We discovered that trametinib remarkably promoted apoptosis and inhibited cell proliferation while inhibition of MEK improved the expression of Tim-3 and caused the decrease of CD8+ T cells; to the contrary, anti-Tim-3 mAb enhanced antitumor immunity by stimulating CD8+ T cells, thus the combined therapy produced potent antitumor effect cooperatively. Taken together, our study provides compelling evidence for combining trametinib and anti-Tim-3 mAb as a potential valuable regimen in treating melanoma.

IL-4-induced caveolin-1-containing lipid rafts aggregation contributes to MUC5AC synthesis in bronchial epithelial cells.

BACKGROUND: Mucus overproduction is an important feature of asthma. Interleukin (IL)-4 is required for allergen-induced airway inflammation and mucus production. MUC5AC gene expression is regulated by transcript factors NF-κB. The intracellular Ca2+ ([Ca2+]i) signal is required for activation of NF-κB. The transient receptor potential canonical 1 (TRPC1) channel has been shown to contribute for agonist-stimulated Ca2+ influx in some types of cells. However, the relationships among IL-4, TRPC1 and mucus overproduction in bronchial epithelial cells (BECs) in asthma are poorly understood. METHODS: BECs were isolated from large bronchial airway of rats and used as cell model. To present changes of lipid raft, caveolin-1 and TRPC1, immunofluorescence staining and sucrose gradient centrifugation were performed. [Ca2+]i was measured after loading with Fura-2. NF-κB activities were measured by an ELISA-based assay. MUC5AC mRNA and protein levels were detected by real-time quantitative RT-PCR, ELISA analysis and immunofluorescence staining respectively. RESULTS: IL-4 induced Ca2+ influx in BECs, and this was blocked by a Ca2+ influx inhibitor (2-APB). 2-APB also prevented MUC5AC protein synthesis induced by IL-4. Depletion of extracellular Ca2+ resulted in partial decrease in expression of MUC5AC in IL-4 treated cells. NF-κB rather than STAT6 activation mediated IL-4-induced MUC5AC protein synthesis. Then the mechanism of Ca2+ influx was investigated. Immunofluorescence staining and sucrose gradient centrifugation revealed that caveolin-1-containing lipid rafts aggregation was involved in TRPC1 activation and Ca2+ influx in BECs. Lastly, the data revealed that blocking lipid rafts aggregation exactly prevented Ca2+ influx, NF-κB activation and MUC5AC synthesis induced by IL-4. CONCLUSIONS: Our results indicate that IL-4-induced caveolin-1-containing lipid rafts aggregation at least partly contributes to MUC5AC synthesis in BECs.

Crosstalk between calpain activation and TGF-ß1 augments collagen-I synthesis in pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease of unknown cause that typically leads to respiratory failure and death within 3-5years of diagnosis. TGF-ß1 is considered a major profibrotic factor. However, TGF-ß1 is necessary but not sufficient to the pathogenesis of fibrotic lesion of the lungs. Recent observations have revealed that calpain, a calcium dependent protease, plays a pivotal role in tissue remodeling and fibrosis. However, the mechanism of calpain mediating pulmonary fibrosis is not understood. Calpain conditional knockout (ER-Cre(+/-)capns1(flox/flox)) mice and primary human lung fibroblasts (HLFs) were used here to investigate the relationship between calpain and TGF-ß1. Calpain knockout mice were protected from fibrotic effects of bleomycin. Bleomycin induced increases in TGF-ß1 via calpain activation in HLFs. Moreover, TGF-ß1 also activated calpain. This crosstalk between calpain activation and TGF-ß1 triggered the downstream signaling pathway including TGF-ß1 Smad2/3 and non-Smad (Akt) pathways, as well as collagen-I synthesis. Taken together, our data indicate that the crosstalk between calpain activation and TGF-ß1 augments collagen-I synthesis in HLFs and in pulmonary fibrosis. Intervention in the crosstalk between calpain activation and TGF-ß1 is a novel potential strategy to prevent pulmonary fibrosis.

Activation of calpain by renin-angiotensin system in pleural mesothelial cells mediates tuberculous pleural fibrosis.

Pleural fibrosis is defined as an excessive deposition of extracellular matrix (ECM) components that results in destruction of the normal pleural tissue architecture. It can result from diverse inflammatory conditions, especially tuberculous pleurisy. Pleural mesothelial cells (PMCs) play a pivotal role in pleural fibrosis. Calpain is a family of calcium-dependent endopeptidases, which plays an important role in ECM remodeling. However, the role of calpain in pleural fibrosis remains unknown. In the present study, we found that tuberculous pleural effusion (TPE) induced calpain activation in PMCs and that inhibition of calpain prevented TPE-induced collagen-I synthesis and cell proliferation of PMCs. Moreover, our data revealed that the levels of angiotensin (ANG)-converting enzyme (ACE) were significantly higher in pleural fluid of patients with TPE than those with malignant pleural effusion, and ACE-ANG II in TPE resulted in activation of calpain and subsequent triggering of the phosphatidylinositol 3-kinase (PI3K)/Akt/NF-κB signaling pathway in PMCs. Finally, calpain activation in PMCs and collagen depositions were confirmed in pleural biopsy specimens from patients with tuberculous pleurisy. Together, these studies demonstrated that calpain is activated by renin-angiotensin system in pleural fibrosis and mediates TPE-induced collagen-I synthesis and proliferation of PMCs via the PI3K/Akt/NF-κB signaling pathway. Calpain in PMCs might be a novel target for intervention in tuberculous pleural fibrosis.

Bleomycin induced epithelial-mesenchymal transition (EMT) in pleural mesothelial cells.

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease characterized by the development of subpleural foci of myofibroblasts that contribute to the exuberant fibrosis. Recent studies revealed that pleural mesothelial cells (PMCs) undergo epithelial-mesenchymal transition (EMT) and play a pivotal role in IPF. In animal model, bleomycin induces pulmonary fibrosis exhibiting subpleural fibrosis similar to what is seen in human IPF. It is not known yet whether bleomycin induces EMT in PMCs. In the present study, PMCs were cultured and treated with bleomycin. The protein levels of collagen-I, mesenchymal phenotypic markers (vimentin and α-smooth muscle actin), and epithelial phenotypic markers (cytokeratin-8 and E-cadherin) were measured by Western blot. PMC migration was evaluated using wound-healing assay of culture PMCs in vitro, and in vivo by monitoring the localization of PMC marker, calretinin, in the lung sections of bleomycin-induced lung fibrosis. The results showed that bleomycin induced increases in collagen-I synthesis in PMC. Bleomycin induced significant increases in mesenchymal phenotypic markers and decreases in epithelial phenotypic markers in PMC, and promoted PMC migration in vitro and in vivo. Moreover, TGF-ß1-Smad2/3 signaling pathway involved in the EMT of PMC was demonstrated. Taken together, our results indicate that bleomycin induces characteristic changes of EMT in PMC and the latter contributes to subpleural fibrosis.

Dissociation of FK506-binding protein 12.6 kD from ryanodine receptor in bronchial smooth muscle cells in airway hyperresponsiveness in asthma.

Airway hyperresponsiveness (AHR) in asthma is predominantly caused by increased sensitivity of bronchial smooth muscle cells (BSMCs) to stimuli. The sarcoplasmic reticulum (SR)-Ca(2+) release channel, known as ryanodine receptor (RyR), mediates the contractive response of BSMCs to stimuli. FK506-binding protein 12.6 kD (FKBP12.6) stabilizes the RyR2 channel in a closed state. However, the interaction of FKBP12.6 with RyR2 in AHR remains unknown. This study examined the interaction of FKBP12.6 with RyR2 in BSMCs in AHR of asthma. The interaction of FKBP12.6 with RyR2 and FKBP12.6 expression was determined in a rat asthma model and in BSMCs treated with inflammatory cytokines. The calcium responses to contractile agonists were determined in BSMCs with overexpression and knockdown of FKBP12.6. Asthmatic serum, IL-5, IL-13, and TNF-α enhance the calcium response of BSMCs to contractile agonists and cause dissociation of FKBP12.6 from RyR2 and a decrease in FKBP12.6 gene expression in BSMCs in culture and in ovalbumin (OVA)-sensitized and -challenged rats. Knockdown of FKBP12.6 in BSMCs causes a decrease in the association of RyR2 with FKBP12.6 and an increase in the calcium response of BSMCs. Overexpression of FKBP12.6 increases the association of FKBP12.6 with RyR2, decreases the calcium response of BSMCs, and normalizes airway responsiveness in OVA-sensitized and -challenged rats. Dissociation of FKBP12.6 from RyR2 in BSMCs is responsible for the increased calcium response contributing to AHR in asthma. Manipulating the interaction of FKBP12.6 with RyR2 might be a novel and useful treatment for asthma.