CGRP is essential for protection against alveolar epithelial cell necroptosis by activating the AMPK/L-OPA1 signaling pathway during acute lung injury

Alveolar epithelial cell (AEC) necroptosis is critical to disrupt the alveolar barrier and provoke acute lung injury (ALI). Here, we define calcitonin gene-related peptide (CGRP), the most abundant endogenous neuropeptide in the lung, as a novel modulator of AEC necroptosis in lipopolysaccharide (LPS)-induced ALI. Upon LPS-induced ALI, overexpression of Cgrp significantly mitigates the inflammatory response, alleviates lung tissue damage, and decreases AEC necroptosis. Similarly, CGRP alleviated AEC necroptosis under the LPS challenge in vitro. Previously, we identified that long optic atrophy 1 (L-OPA1) deficiency mediates mitochondrial fragmentation, leading to AEC necroptosis. In this study, we discovered that CGRP positively regulated mitochondrial fusion through stabilizing L-OPA1. Mechanistically, we elucidate that CGRP activates AMP-activated protein kinase (AMPK). Furthermore, the blockade of AMPK compromised the protective effect of CGRP against AEC necroptosis following the LPS challenge. Our study suggests that CRGP-mediated activation of the AMPK/L-OPA1 axis may have potent therapeutic benefits for patients with ALI or other diseases with necroptosis.

Epoxyeicosatrienoic acids alleviate alveolar epithelial cell senescence by inhibiting mitophagy through NOX4/Nrf2 pathway

Alveolar epithelial cell (AEC) senescence is considered to be a universal pathological feature of many chronic pulmonary diseases. Our previous study found that epoxyeicosatrienoic acids (EETs), produced from arachidonic acid (ARA) through the cytochrome P450 cyclooxygenase (CYP) pathway, have significant negative regulatory effects on cellular senescence in AECs. However, the exact mechanisms by which EETs alleviate the senescence of AECs still need to be further explored. In the present study, we observed that bleomycin (BLM) induced enhanced mitophagy accompanied by increased mitochondrial ROS (mito-ROS) content in the murine alveolar epithelial cell line MLE12. While EETs reduced BLM-induced mitophagy and mito-ROS content in MLE12 cells, and the mechanism was related to the regulation of NOX4/Nrf2-mediated redox imbalance. Furthermore, we found that inhibition of EETs degradation could significantly inhibit mitophagy and regulate NOX4/Nrf2 balance to exert anti-oxidant effects in D-galactose-induced premature aging mice. Collectively, these findings may provide new ideas for treating age-related pulmonary diseases by targeting EETs to improve mitochondrial dysfunction and reduce oxidative stress.

The role of vasoactive intestinal peptide in pulmonary diseases

Vasoactive intestinal peptide (VIP) is an abundant neurotransmitter in the lungs and other organs. Its discovery dates back to 1970. And VIP gains attention again due to the potential application in COVID-19 after a research wave in the 1980s and 1990s. The diverse biological impacts of VIP extend beyond its usage in COVID-19 treatment, encompassing its involvement in various pulmonary and systemic disorders. This review centers on the function of VIP in various lung diseases, such as pulmonary arterial hypertension, chronic obstructive pulmonary disease, asthma, cystic fibrosis, acute lung injury/acute respiratory distress syndrome, pulmonary fibrosis, and lung tumors. This review also outlines two main limitations of VIP as a potential medication and gathers information on extended-release formulations and VIP analogues.

Mitochondrial citrate accumulation triggers senescence of alveolar epithelial cells contributing to pulmonary fibrosis in mice

Alveolar epithelial cell (AEC) senescence is implicated in the pathogenesis of pulmonary fibrosis (PF). However, the exact mechanism underlying AEC senescence during PF remains poorly understood. Here, we reported an unrecognized mechanism for AEC senescence during PF. We found that, in bleomycin (BLM)-induced PF mice, the expressions of isocitrate dehydrogenase 3α (Idh3α) and citrate carrier (CIC) were significantly down-regulated in the lungs, which could result in mitochondria citrate (citrate^mt) accumulation in our previous study. Notably, the down-regulation of Idh3α and CIC was related to senescence. The mice with AECs-specific Idh3α and CIC deficiency by adenoviral vector exhibited spontaneous PF and senescence in the lungs. In vitro, co-inhibition of Idh3α and CIC with shRNA or inhibitors triggered the senescence of AECs, indicating that accumulated citrate^mt triggers AEC senescence. Mechanistically, citrate^mt accumulation impaired the mitochondrial biogenesis of AECs. In addition, the senescence-associated secretory phenotype from senescent AECs induced by citrate^mt accumulation activated the proliferation and transdifferentiation of NIH3T3 fibroblasts into myofibroblasts. In conclusion, we show that citrate^mt accumulation would be a novel target for protection against PF that involves senescence.

EETs alleviate alveolar epithelial cell senescence by inhibiting endoplasmic reticulum stress through the Trim25/Keap1/Nrf2 axis

Alveolar epithelial cell (AEC) senescence is a key driver of a variety of chronic lung diseases. It remains a challenge how to alleviate AEC senescence and mitigate disease progression. Our study identified a critical role of epoxyeicosatrienoic acids (EETs), downstream metabolites of arachidonic acid (ARA) by cytochrome p450 (CYP), in alleviating AEC senescence. In vitro, we found that 14,15-EET content was significantly decreased in senescent AECs. Exogenous EETs supplementation, overexpression of CYP2J2, or inhibition of EETs degrading enzyme soluble epoxide hydrolase (sEH) to increase EETs alleviated AECs' senescence. Mechanistically, 14,15-EET promoted the expression of Trim25 to ubiquitinate and degrade Keap1 and promoted Nrf2 to enter the nucleus to exert an anti-oxidant effect, thereby inhibiting endoplasmic reticulum stress (ERS) and alleviating AEC senescence. Furthermore, in D-galactose (D-gal)-induced premature aging mouse model, inhibiting the degradation of EETs by Trifluoromethoxyphenyl propionylpiperidin urea (TPPU, an inhibitor of sEH) significantly inhibited the protein expression of p16, p21, and γH2AX. Meanwhile, TPPU reduced the degree of age-related pulmonary fibrosis in mice. Our study has confirmed that EETs are novel anti-senescence substances for AECs, providing new targets for the treatment of chronic lung diseases.

TREM-1 triggers necroptosis of macrophages through mTOR-dependent mitochondrial fission during acute lung injury

BACKGROUND

Necroptosis of macrophages is a necessary element in reinforcing intrapulmonary inflammation during acute lung injury (ALI). However, the molecular mechanism that sparks macrophage necroptosis is still unclear. Triggering receptor expressed on myeloid cells-1 (TREM-1) is a pattern recognition receptor expressed broadly on monocytes/macrophages. The influence of TREM-1 on the destiny of macrophages in ALI requires further investigation.

METHODS

TREM-1 decoy receptor LR12 was used to evaluate whether the TREM-1 activation induced necroptosis of macrophages in lipopolysaccharide (LPS)-induced ALI in mice. Then we used an agonist anti-TREM-1 Ab (Mab1187) to activate TREM-1 in vitro. Macrophages were treated with GSK872 (a RIPK3 inhibitor), Mdivi-1 (a DRP1 inhibitor), or Rapamycin (an mTOR inhibitor) to investigate whether TREM-1 could induce necroptosis in macrophages, and the mechanism of this process.

RESULTS

We first observed that the blockade of TREM-1 attenuated alveolar macrophage (AlvMs) necroptosis in mice with LPS-induced ALI. In vitro, TREM-1 activation induced necroptosis of macrophages. mTOR has been previously linked to macrophage polarization and migration. We discovered that mTOR had a previously unrecognized function in modulating TREM-1-mediated mitochondrial fission, mitophagy, and necroptosis. Moreover, TREM-1 activation promoted DRP1^Ser616 phosphorylation through mTOR signaling, which in turn caused surplus mitochondrial fission-mediated necroptosis of macrophages, consequently exacerbating ALI.

CONCLUSION

In this study, we reported that TREM-1 acted as a necroptotic stimulus of AlvMs, fueling inflammation and aggravating ALI. We also provided compelling evidence suggesting that mTOR-dependent mitochondrial fission is the underpinning of TREM-1-triggered necroptosis and inflammation. Therefore, regulation of necroptosis by targeting TREM-1 may provide a new therapeutic target for ALI in the future.

TREM-1 governs NLRP3 inflammasome activation of macrophages by firing up glycolysis in acute lung injury

The triggering receptor expressed on myeloid cells-1 (TREM-1) is a pro-inflammatory immune receptor potentiating acute lung injury (ALI). However, the mechanism of TREM-1-triggered inflammation response remains poorly understood. Here, we showed that TREM-1 blocking attenuated NOD-, LRR- and pyrin domain-containing 3 (NLRP3) inflammasome activation and glycolysis in LPS-induced ALI mice. Then, we observed that TREM-1 activation enhanced glucose consumption, induced glycolysis, and inhibited oxidative phosphorylation in macrophages. Specifically, inhibition of glycolysis with 2-deoxyglucose diminished NLRP3 inflammasome activation of macrophages triggered by TREM-1. Hypoxia-inducible factor-1α (HIF-1α) is a critical transcriptional regulator of glycolysis. We further found that TREM-1 activation facilitated HIF-1α accumulation and translocation to the nucleus via the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway. Inhibiting mTOR or HIF-1α also suppressed TREM-1-induced metabolic reprogramming and NLRP3/caspase-1 activation. Overall, the mTOR/HIF-1α/glycolysis pathway is a novel mechanism underlying TREM-1-governed NLRP3 inflammasome activation. Therapeutic targeting of the mTOR/HIF-1α/glycolysis pathway in TREM-1-activated macrophages could be beneficial for treating or preventing inflammatory diseases, such as ALI.

Mitochondrial citrate accumulation drives alveolar epithelial cell necroptosis in lipopolysaccharide-induced acute lung injury

Necroptosis is the major cause of death in alveolar epithelial cells (AECs) during acute lung injury (ALI). Here, we report a previously unrecognized mechanism for necroptosis. We found an accumulation of mitochondrial citrate (citrate^mt) in lipopolysaccharide (LPS)-treated AECs because of the downregulation of Idh3α and citrate carrier (CIC, also known as Slc25a1). shRNA- or inhibitor-mediated inhibition of Idh3α and Slc25a1 induced citrate^mt accumulation and necroptosis in vitro. Mice with AEC-specific Idh3α and Slc25a1 deficiency exhibited exacerbated lung injury and AEC necroptosis. Interestingly, the overexpression of Idh3α and Slc25a1 decreased citrate^mt levels and rescued AECs from necroptosis. Mechanistically, citrate^mt accumulation induced mitochondrial fission and excessive mitophagy in AECs. Furthermore, citrate^mt directly interacted with FUN14 domain-containing protein 1 (FUNDC1) and promoted the interaction of FUNDC1 with dynamin-related protein 1 (DRP1), leading to excessive mitophagy-mediated necroptosis and thereby initiating and promoting ALI. Importantly, necroptosis induced by citrate^mt accumulation was inhibited in FUNDC1-knockout AECs. We show that citrate^mt accumulation is a novel target for protection against ALI involving necroptosis.

Sepsis-induced immunosuppression: mechanisms, diagnosis and current treatment options

Sepsis is a common complication of combat injuries and trauma, and is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. It is also one of the significant causes of death and increased health care costs in modern intensive care units. The use of antibiotics, fluid resuscitation, and organ support therapy have limited prognostic impact in patients with sepsis. Although its pathophysiology remains elusive, immunosuppression is now recognized as one of the major causes of septic death. Sepsis-induced immunosuppression is resulted from disruption of immune homeostasis. It is characterized by the release of anti-inflammatory cytokines, abnormal death of immune effector cells, hyperproliferation of immune suppressor cells, and expression of immune checkpoints. By targeting immunosuppression, especially with immune checkpoint inhibitors, preclinical studies have demonstrated the reversal of immunocyte dysfunctions and established host resistance. Here, we comprehensively discuss recent findings on the mechanisms, regulation and biomarkers of sepsis-induced immunosuppression and highlight their implications for developing effective strategies to treat patients with septic shock.

Fn14 exacerbates acute lung injury by activating the NLRP3 inflammasome in mice

BACKGROUND

Uncontrolled inflammation is an important factor in the occurrence and development of acute lung injury (ALI). Fibroblast growth factor-inducible 14 (Fn14), a plasma membrane-anchored receptor, takes part in the pathological process of a variety of acute and chronic inflammatory diseases. However, the role of Fn14 in ALI has not yet been elucidated. This study aimed to investigate whether the activation of Fn14 exacerbated lipopolysaccharide (LPS)-induced ALI in mice.

METHODS

In vivo, ALI was induced by intratracheal LPS-challenge combined with/without Fn14 receptor blocker aurintricarboxylic acid (ATA) treatment in C57BL/6J mice. Following LPS administration, the survival rate, lung tissue injury, inflammatory cell infiltration, inflammatory factor secretion, oxidative stress, and NLRP3 inflammasome activation were assessed. In vitro, primary murine macrophages were used to evaluate the underlying mechanism by which Fn14 activated the NLRP3 inflammasome. Lentivirus was used to silence Fn14 to observe its effect on the activation of NLRP3 inflammasome in macrophages.

RESULTS

In this study, we found that Fn14 expression was significantly increased in the lungs of LPS-induced ALI mice. The inhibition of Fn14 with ATA downregulated the protein expression of Fn14 in the lungs and improved the survival rate of mice receiving a lethal dose of LPS. ATA also attenuated lung tissue damage by decreasing the infiltration of macrophages and neutrophils, reducing inflammation, and suppressing oxidative stress. Importantly, we found that ATA strongly inhibited the activation of NLRP3 inflammasome in the lungs of ALI mice. Furthermore, in vitro, TWEAK, a natural ligand of Fn14, amplified the activation of NLRP3 inflammasome in the primary murine macrophage. By contrast, inhibition of Fn14 with shRNA decreased the expression of Fn14, NLRP3, Caspase-1 p10, and Caspase-1 p20, and the production of IL-1β and IL-18. Furthermore, the activation of Fn14 promoted the production of reactive oxygen species and inhibited the activation of Nrf2-HO-1 in activated macrophages.

CONCLUSIONS

Our study first reports that the activation of Fn14 aggravates ALI by amplifying the activation of NLRP3 inflammasome. Therefore, blocking Fn14 may be a potential way to treat ALI.

Beneficial effects of aloperine on inflammation and oxidative stress by suppressing necroptosis in lipopolysaccharide-induced acute lung injury mouse model

RATIONALE

Alveolar epithelial cell death, inflammation, and oxidative stress are typical features of acute lung injury (ALI). Aloperine (Alo), an alkaloid isolated from Sophora alopecuroides, has been reported to display various biological effects, such as anti-inflammatory, immunoregulatory, and anti-oxidant properties. In this study, we investigated the effects and mechanisms of Alo in treating a lipopolysaccharide (LPS)-induced ALI in a murine model.

METHODS

The effects of Alo in LPS-induced ALI were investigated in C57BL/6 mice. The RIPK1 inhibitor (Nec-1) and the RIPK3 inhibitor (GSK'872) were used to evaluate the relationship of necroptosis, NF-κB activation, and PDC subunits in LPS-treated mouse alveolar epithelial cells (MLE-12). Then the effects of Alo on necroptosis, inflammation, and oxidative stress of LPS-stimulated MLE-12 cells were evaluated.

RESULTS

Alo significantly attenuated histopathological lung injuries and reduced lung wet/dry ratio in LPS-induced ALI mice. Alo also remarkedly reduced total protein and neutrophils recruitment in bronchoalveolar lavage fluid of ALI mice. Meanwhile, Alo ameliorated the LPS-induced necroptosis in the lungs of ALI mice. The RIPK3 inhibitor GSK'872, but not the RIPK1 inhibitor Nec-1, reversed LPS-induced p65 phosphorylation and translocation to the nucleus in MLE-12 cells. GSK'872 also reversed the LPS-induced increase in ROS and binding of RIPK3 and PDC subunits in MLE-12 cells. Moreover, Alo down-regulated the levels of p-RIPK1, p-RIPK3, p-MLKL, p-p65, the translocation of p65 to the nucleus, and reduced the expression of IL-6 and IL-8 in LPS-stimulated MLE-12 cells. Alo also inhibited the binding of RIPK3 and PDC-E1α, PDC-E1β, PDC-E2, and PDC-E3 and the ROS production in LPS-treated MLE-12 cells.

CONCLUSION

The present study validated the beneficial effects of Alo on LPS-induced ALI , suggesting Alo may be a new drug candidate against ALI.

L-OPA1 deficiency aggravates necroptosis of alveolar epithelial cells through impairing mitochondrial function during ALI in mice

Necroptosis, a recently described form of programmed cell death, is the main way of alveolar epithelial cells (AECs) death in acute lung injury (ALI). While the mechanism of how to trigger necroptosis in AECs during ALI has been rarely evaluated. Long optic atrophy protein 1 (L-OPA1) is a crucial mitochondrial inner membrane fusion protein, and its deficiency impairs mitochondrial function. This study aimed to investigate the role of L-OPA1 deficiency-mediated mitochondrial dysfunction in AECs necroptosis. We comprehensively investigated the detailed contribution and molecular mechanism of L-OPA1 deficiency in AECs necroptosis by inhibiting or activating L-OPA1. Firstly, our data showed that L-OPA1 expression was down-regulated in the lungs and AECs under the lipopolysaccharide (LPS) challenge. Furthermore, inhibition of L-OPA1 aggravated the pathological injury, inflammatory response, and necroptosis in the lungs of LPS-induced ALI mice. In vitro, inhibition of L-OPA1 induced necroptosis of AECs, while activation of L-OPA1 alleviated necroptosis of AECs under the LPS challenge. Mechanistically, inhibition of L-OPA1 aggravated necroptosis of AECs by inducing mitochondrial fragmentation and reducing mitochondrial membrane potential. While activation of L-OPA1 had the opposite effects. In summary, these findings indicate for the first time that L-OPA1 deficiency mediates mitochondrial fragmentation, induces necroptosis of AECs, and exacerbates ALI in mice. This article is protected by copyright. All rights reserved.

Activation of NLRP3 inflammasome up-regulates TREM-1 expression in murine macrophages via HMGB1 and IL-18

•

NLRP3 inflammasome inhibition reduces TREM-1 expression in the lungs of mice with ALI.

•

Activation of NLRP3 inflammasome up-regulates TREM-1 expression in murine macrophages via HMGB1 and IL-18.

•

NLRP3 inflammasome activation induces TREM-1 expression, contributing to the inflammatory network in the lungs of ALI mice.

NOD-, LRR- and pyrin domain-containing 3 (NLRP3) inflammasome and triggering receptor expressed on myeloid cells-1 (TREM-1) are considered critical orchestrators of the inflammatory response in acute lung injury (ALI). However, few assumptions are based on the relationship between them. Here, we investigated the effect of NLRP3 inflammasome activation on the TREM-1 expression in lipopolysaccharide (LPS)-induced ALI and macrophages. We found that inhibition of the NLRP3 inflammasome reduced the TREM-1 expression and pathological lung injury in mice with ALI. Then, primary murine macrophages were used to dissect the underlying mechanistic events of the activation NLRP3 inflammasome involved in the TREM-1 expression. Our results demonstrated that the conditioned medium (CM) from NLRP3 inflammasome-activated-macrophages up-regulated the TREM-1 expression in macrophages, while this effect was reversed by an NLRP3 inflammasome inhibitor MCC950. Furthermore, neutralizing antibodies anti-IL-18 and anti-HMGB1 reduced the TREM-1 expression induced by NLRP3 inflammasome activation. Mechanistically, we found that CM from NLRP3 inflammasome-activated-macrophages increased the level of inhibitor κB kinase protein phosphorylation (p-IκBα) and reactive oxygen species (ROS) content, and promoted IκBα protein degradation in macrophages. While the inhibition of nuclear factor kappa-B (NF-κB) and scavenging ROS eliminated the up-regulation of TREM-1 induced by the NLRP3 inflammasome activation in macrophages. In summary, our study confers NLRP3 inflammasome as a new trigger of TREM-1 signing, which allows additional insight into the pathological of the inflammatory response in ALI.

The role of NOX4 in pulmonary diseases

Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) is a subtype of the NOX family, which is mainly expressed in the pulmonary vasculature and pulmonary endothelial cells in the respiratory system. NOX4 has unique characteristics, and is a constitutively active enzyme that primarily produces hydrogen peroxide. The signaling pathways associated with NOX4 are complicated. Negative and positive feedback play significant roles in regulating NOX4 expression. The role of NOX4 is controversial because NOX4 plays a protective or damaging role in different respiratory diseases. This review summarizes the structure, enzymatic properties, regulation, and signaling pathways of NOX4. This review then introduces the roles of NOX4 in different diseases in the respiratory system, such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis.

Genomic Analysis Identifies Mutations Concerning Drug-Resistance and Beijing Genotype in Multidrug-Resistant Mycobacterium tuberculosis Isolated From China

Development of modern genomics provides us an effective method to understand the molecular mechanism of drug resistance and diagnose drug-resistant Mycobacterium tuberculosis. In this study, mutations in 18 genes or intergenic regions acquired by whole-genome sequencing (WGS) of 183 clinical M. tuberculosis strains, including 137 multidrug-resistant and 46 pan-susceptible isolates from China, were identified and used to analyze their associations with resistance of isoniazid, rifampin, ethambutol, and streptomycin. Using the proportional method as the gold standard method, the accuracy values of WGS to predict resistance were calculated. The association between synonymous or lineage definition mutations with different genotypes were also analyzed. The results show that, compared to the phenotypic proportional method, the sensitivity and specificity of WGS for resistance detection were 94.2 and 100.0% for rifampicin (based on mutations in rpoB), 90.5 and 97.8% for isoniazid (katG), 83.0 and 97.8% for streptomycin (rpsL combined with rrs 530 loop and 912 loop), and 90.9 and 65.1% for ethambutol (embB), respectively. WGS data also showed that mutations in the inhA promoter increased only 2.2% sensitivity for INH based on mutations in katG. Synonymous mutation rpoB A1075A was confirmed to be associated with the Beijing genotype. This study confirmed that mutations in rpoB, katG, rrs 530 loop and 912 loop, and rpsL were excellent biomarkers for predicting rifampicin, isoniazid, and streptomycin resistance, respectively, and provided clues in clarifying the drug-resistance mechanism of M. tuberculosis isolates from China.

Epoxyeicosatrienoic acids inhibit the activation of NLRP3 inflammasome in murine macrophages

Epoxyeicosatrienoic acids (EETs) derived from arachidonic acid exert anti-inflammation effects. We have reported that blocking the degradation of EETs with a soluble epoxide hydrolase (sEH) inhibitor protects mice from lipopolysaccharide (LPS)-induced acute lung injury (ALI). The underlying mechanisms remain essential questions. In this study, we investigated the effects of EETs on the activation of nucleotide-binding domain leucine-rich repeat-containing receptor, pyrin domain-containing-3 (NLRP3) inflammasome in murine macrophages. In an LPS-induced ALI murine model, we found that sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl), TPPU, profoundly attenuated the pathological injury and inhibited the activation of the NLRP3 inflammasome, characterized by the reduction of the protein expression of NLRP3, ASC, pro-caspase-1, interleukin precursor (pro-IL-1β), and IL-1β p17 in the lungs of LPS-treated mice. In vitro, primary peritoneal macrophages from C57BL/6 were primed with LPS and activated with exogenous adenosine triphosphate (ATP). TPPU treatment remarkably reduced the expression of NLRP3 inflammasome-related molecules and blocked the activation of NLRP3 inflammasome. Importantly, four EETs (5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET) inhibited the activation of NLRP3 inflammasome induced by LPS + ATP or LPS + nigericin in macrophages in various degree. While the inhibitory effect of 5,6-EET was the weakest. Mechanismly, EETs profoundly decreased the content of reactive oxygen species (ROS) and restored the calcium overload in macrophages receiving LPS + ATP stimulation. In conclusion, this study suggests that EETs inhibit the activation of the NLRP3 inflammasome by suppressing calcium overload and ROS production in macrophages, contributing to the therapeutic potency to ALI.

Accuracy of a reverse dot blot hybridization assay for simultaneous detection of the resistance of four anti-tuberculosis drugs in Mycobacterium tuberculosis isolated from China

Background

Drug resistant tuberculosis poses a great challenge for tuberculosis control worldwide. Timely determination of drug resistance and effective individual treatment are essential for blocking the transmission of drug resistant Mycobacterium tuberculosis. We aimed to establish and evaluate the accuracy of a reverse dot blot hybridization (RDBH) assay to simultaneously detect the resistance of four anti-tuberculosis drugs in M. tuberculosis isolated in China.

Methods

In this study, we applied a RDBH assay to simultaneously detect the resistance of rifampicin (RIF), isoniazid (INH), streptomycin (SM) and ethambutol (EMB) in 320 clinical M. tuberculosis isolates and compared the results to that from phenotypic drug susceptibility testing (DST) and sequencing. The RDBH assay was designed to test up to 42 samples at a time. Pearson’s chi-square test was used to compute the statistical measures of the RDBH assay using the phenotypic DST or sequencing as the gold standard method, and Kappa identity test was used to determine the consistency between the RDBH assay and the phenotypic DST or sequencing.

Results

The results showed that the concordances between phenotypic DST and RDBH assay were 95% for RIF, 92.8% for INH, 84.7% for SM, 77.2% for EMB and the concordances between sequencing and RDBH assay were 97.8% for RIF, 98.8% for INH, 99.1% for SM, 93.4% for EMB. Compared to the phenotypic DST results, the sensitivity and specificity of the RDBH assay for resistance detection were 92.4 and 98.5% for RIF, 90.3 and 97.3% for INH, 77.4 and 91.5% for SM, 61.4 and 85.7% for EMB, respectively; compared to sequencing, the sensitivity and specificity of the RDBH assay were 97.7 and 97.9% for RIF, 97.9 and 100.0% for INH, 97.8 and 100.0% for SM, 82.6 and 99.1% for EMB, respectively. The turnaround time of the RDBH assay was 7 h for testing 42 samples.

Conclusions

Our data suggested that the RDBH assay could serve as a rapid and efficient method for testing the resistance of M. tuberculosis against RIF, INH, SM and EMB, enabling early administration of appropriate treatment regimens to the affected drug resistant tuberculosis patients.

A COX-2/sEH dual inhibitor PTUPB alleviates lipopolysaccharide-induced acute lung injury in mice by inhibiting NLRP3 inflammasome activation

Rationale: Dysregulation of arachidonic acid (ARA) metabolism results in inflammation; however, its role in acute lung injury (ALI) remains elusive. In this study, we addressed the role of dysregulated ARA metabolism in cytochromes P450 (CYPs) /cyclooxygenase-2 (COX-2) pathways in the pathogenesis of lipopolysaccharide (LPS)-induced ALI in mice. Methods: The metabolism of CYPs/COX-2-derived ARA in the lungs of LPS-induced ALI was investigated in C57BL/6 mice. The COX-2/sEH dual inhibitor PTUPB was used to establish the function of CYPs/COX-2 dysregulation in ALI. Primary murine macrophages were used to evaluate the underlying mechanism of PTUPB involved in the activation of NLRP3 inflammasome in vitro. Results: Dysregulation of CYPs/COX-2 metabolism of ARA occurred in the lungs and in primary macrophages under the LPS challenge. Decrease mRNA expression of Cyp2j9, Cyp2j6, and Cyp2j5 was observed, which metabolize ARA into epoxyeicosatrienoic acids (EETs). The expressions of COX-2 and soluble epoxide hydrolase (sEH), on the other hand, was significantly upregulated. Pre-treatment with the dual COX-2 and sEH inhibitor, PTUPB, attenuated the pathological injury of lung tissues and reduced the infiltration of inflammatory cells. Furthermore, PTUPB decreased the pro-inflammatory factors, oxidative stress, and activation of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in LPS-induced ALI mice. PTUPB pre-treatment remarkably reduced the activation of macrophages and NLRP3 inflammasome in vitro. Significantly, both preventive and therapeutic treatment with PTUPB improved the survival rate of mice receiving a lethal dose of LPS. Conclusion: The dysregulation of CYPs/COX-2 metabolized ARA contributes to the uncontrolled inflammatory response in ALI. The dual COX-2 and sEH inhibitor PTUPB exerts anti-inflammatory effects in treating ALI by inhibiting the NLRP3 inflammasome activation.

A COX-2/sEH dual inhibitor PTUPB ameliorates cecal ligation and puncture-induced sepsis in mice via anti-inflammation and anti-oxidative stress

Arachidonic acid can be metabolized to prostaglandins and epoxyeicosatrienoic acids (EETs) by cyclooxygenase-2 (COX-2) and cytochrome P450 (CYP), respectively. While protective EETs are degraded by soluble epoxide hydrolase (sEH) very fast. We have reported that dual inhibition of COX-2 and sEH with specific inhibitor PTUPB shows anti-pulmonary fibrosis and renal protection. However, the effect of PTUPB on cecal ligation and puncture (CLP)-induced sepsis remains unclear. The current study aimed to investigate the protective effects of PTUPB against CLP-induced sepsis in mice and the underlying mechanisms. We found that COX-2 expressions were increased, while CYPs expressions were decreased in the liver, lung, and kidney of mice undergone CLP. PTUPB treatment significantly improved the survival rate, reduced the clinical scores and systemic inflammatory response, alleviated liver and kidney dysfunction, and ameliorated the multiple-organ injury of the mice with sepsis. Besides, PTUPB treatment reduced the expression of hypoxia-inducible factor-1α in the liver, lung, and kidney of septic mice. Importantly, we found that PTUPB treatment suppressed the activation of NLRP3 inflammasome in the liver and lung of septic mice. Meanwhile, we found that PTUPB attenuated the oxidative stress, which contributed to the activation of NLRP3 inflammasome. Altogether, our data, for the first time, demonstrate that dual inhibition of COX-2 and sEH with PTUPB ameliorates the multiple organ dysfunction in septic mice.

Psoralen attenuates bleomycin-induced pulmonary fibrosis in mice through inhibiting myofibroblast activation and collagen deposition

Idiopathic pulmonary fibrosis (IPF) is a progressive disease characterized by excessive deposition of extracellular matrix (ECM) and chronic inflammation with limited therapeutic options. Psoralen, a major active component extracted from Psoralea corylifolia L. seed, has several biological effects. However, the role of psoralen in IPF is still unclear. Here, we hypothesized that psoralen played an essential role in IPF in the inhibition of fibroblast proliferation and inflammatory response. A murine model of IPF was established by injecting bleomycin (BLM) intratracheally, and psoralen was administered for 14 days from the 7^th to 21^st day after BLM injection. Our results demonstrated that psoralen treatment reduced body weight loss and improved the survival rate of mice with IPF. Histological and immunofluorescent examination showed that psoralen alleviated BLM-induced lung parenchymal inflammatory and fibrotic alteration. Furthermore, psoralen inhibited proliferation and collagen synthesis of mouse fibroblasts and partially reversed BLM-induced expression of α-smooth muscle actin at both the tissue and cell level. Moreover, psoralen decreased the expression of transforming growth factor-β1, interleukin-1β, and tumor necrosis factor-α in the lungs of BLM-stimulated mice. Our results reveale for the first time that psoralen exerts therapeutic effects against IPF in a BLM-induced murine model.

COX-2/sEH dual inhibitor PTUPB alleviates bleomycin-induced pulmonary fibrosis in mice via inhibiting senescence

Pulmonary fibrosis (PF) is a senescence-associated disease with poor prognosis. Currently, there is no effective therapeutic strategy for preventing and treating the disease process. Mounting evidence suggests that arachidonic acid (ARA) metabolites are involved in the pathogenesis of various fibrosis. However, the relationship between the metabolism of ARA and PF is still elusive. In this study, we observed a disorder in the cyclooxygenase-2/cytochrome P450 (COX-2/CYP) metabolism of ARA in the lungs of PF mice induced by bleomycin (BLM). Therefore, we aimed to explore the role of COX-2/CYP-derived ARA metabolic disorders in PF. PTUPB, a dual COX-2 and soluble epoxide hydrolase (sEH) inhibitor, was used to restore the balance of COX-2/CYP metabolism. sEH is an enzyme hydrolyzing epoxyeicosatrienoic acids derived from ARA by CYP. We found that PTUPB alleviated the pathological changes in lung tissue and collagen deposition, as well as reduced senescence marker molecules (p16^Ink4a and p53-p21^Waf1/Cip1 ) in the lungs of mice treated by BLM. In vitro, we found that PTUPB pretreatment remarkably reduced the expression of senescence-related molecules in the alveolar epithelial cells (AECs) induced by BLM. In conclusion, our study supports the notion that the COX-2/CYP-derived ARA metabolic disorders may be a potential therapeutic target for PF via inhibiting the cellular senescence in AECs.

Vasoactive intestinal peptide inhibits the activation of murine fibroblasts and expression of interleukin 17 receptor C

Acute respiratory distress syndrome (ARDS) is an acute, severe, and refractory pulmonary inflammation with high morbidity and mortality. Excessive activation of fibroblast during the fibroproliferative phase plays a pivotal role in the prognosis of ARDS. Our previous study demonstrated that the vasoactive intestinal peptide (VIP) is mediated by lentivirus attenuates lipopolysaccharide (LPS)-induced ARDS in a murine model, and VIP inhibits the release of interleukin-17A (IL-17A) from activation macrophages. However, the effects of VIP on the activation of murine fibroblast and expression of IL-17 receptor (IL-17R) in ARDS remain unclear. Here, a mouse model of ARDS was established by an intratracheal injection of LPS. We found that the gene expression of col3a1 and hydroxyproline contents in the lungs were significantly increased 24 h after LPS injection. IL-17RC rather than IL-17RA was increased in the lungs of mice with ARDS. In vitro, LPS activated NIH3T3 cells, which was suppressed by VIP in a dose-dependent manner. In detail, VIP reduced the hydroxyproline content and col3a1 messenger RNA induced by LPS in NIH3T3 cells, as well as the expression of α-smooth muscle actin. Furthermore, we found that VIP inhibited the expression of IL-17R in the lungs of mice with ARDS and NIH3T3 cells stimulated with LPS, which was partly inhibited by antagonists of protein kinase A and protein kinase C. Taken together, our results demonstrated that VIP inhibited the activation of fibroblast via downregulation of IL-17RC, which may contribute to the protective effects of VIP against ARDS in mice.

Aucubin Alleviates Bleomycin-Induced Pulmonary Fibrosis in a Mouse Model

Pulmonary fibrosis is a life-threatening disease characterized by progressive dyspnea and worsening of pulmonary function. No effective therapeutic strategy for pulmonary fibrosis has been established. Aucubin is a natural constituent with a monoterpene cyclic ring system. The potency of aucubin in protecting cellular components against inflammation, oxidative stress, and proliferation effects is well documented. In this study, we investigated the protective effect of aucubin against pulmonary fibrosis in mice. A mouse model of pulmonary fibrosis was established by intratracheal injection of bleomycin (BLM), and aucubin was administered for 21 days after BLM injection. We found that aucubin decreased the breathing frequency and increased the lung dynamic compliance of BLM-stimulated mice detected by Buxco pulmonary function testing system. Histological examination showed that aucubin alleviated BLM-induced lung parenchymal fibrotic changes. Aucubin also reduced the intrapulmonary collagen disposition and inflammatory injury induced by BLM. In addition, aucubin reduced the expression of pro-fibrotic protein transforming growth factor (TGF)-β1 and α-smooth muscle actin (α-SMA) of pulmonary fibrosis mice induced by BLM. Furthermore, the effect of aucubin on the proliferation and differentiation of fibroblast was investigated in vitro. Aucubin inhibited the mRNA and protein expression of Ki67 and proliferating cell nuclear antigen (PCNA) induced by TGF-β1 and reduced the cell proliferation in a murine fibroblast cell NIH3T3. Aucubin also reduced the collagen syntheses and α-SMA expression induced by TGF-β1 in fibroblast. Our results indicate that aucubin inhibits inflammation, fibroblast proliferation, and differentiation, exerting protective effects against BLM-induced pulmonary fibrosis in a mouse model. This study provides an evidence that aucubin may be a novel drug for pulmonary fibrosis.

Vasoactive intestinal peptide overexpression mediated by lentivirus attenuates lipopolysaccharide-induced acute lung injury in mice by inhibiting inflammation

Vasoactive intestinal peptide (VIP) is one of the most abundant neuropeptides in the lungs with various biological characters. We have reported that VIP inhibited the expressions of TREM-1 and IL-17A, which are involved in the initiation and amplification of inflammation in acute lung injury (ALI). However, the overall effect of VIP on ALI remains unknown. The aim of this study is to investigate the therapeutic effect of VIP mediated by lentivirus (Lenti-VIP) on lipopolysaccharide (LPS)-induced murine ALI. We found that the expression of intrapulmonary VIP peaked at day7 after the intratracheal injection of Lenti-VIP. Lenti-VIP increased the respiratory rate, lung compliance, and tidal volume, while decreased airway resistance in ALI mice, detected by Buxco system. Lenti-VIP significantly reduced inflammatory cell infiltration and maintained the integrity of the alveolar septa. Lenti-VIP also remarkably decreased the total protein level, the number of neutrophil and lactate dehydrogenase activity in the bronchoalveolar lavage fluid of LPS-induced ALI mice. In addition, Lenti-VIP down-regulated pro-inflammatory tumor necrosis factor (TNF)-α mRNA and protein expression, while up-regulated anti-inflammatory interleukin-10 mRNA and protein expression in lungs of ALI mice. Furthermore, we observed that VIP reduced the TNF-α expression in murine macrophages under LPS stimulation through protein kinase C and protein kinase A pathways. Together, our findings show that in vivo administration of lentivirus expressing VIP exerts a potent therapeutic effect on LPS-induced ALI in mice via inhibiting inflammation.

Soluble Epoxide Hydrolase Inhibitor Suppresses the Expression of Triggering Receptor Expressed on Myeloid Cells-1 by Inhibiting NF-kB Activation in Murine Macrophage

Triggering receptors expressed on myeloid cell-1 (TREM-1) is a superimmunoglobulin receptor expressed on myeloid cells. TREM-1 amplifies the inflammatory response. Epoxyeicosatrienoic acids (EETs), the metabolites of arachidonic acid derived from the cytochrome P450 enzyme, have anti-inflammatory properties. However, the effects of EETs on TREM-1 expression under inflammatory stimulation remain unclear. Therefore, inhibition of soluble epoxide hydrolase (sEH) with a highly selective inhibitor [1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea, TPPU] was used to stabilize EETs. LPS was intratracheally injected into mice to induce pulmonary inflammation, after TPPU treatment for 3 h. Histological examination showed TPPU treatment-alleviated LPS-induced pulmonary inflammation. TPPU decreased TREM-1 expression, but not DAP12 or MyD88 expression. Murine peritoneal macrophages were challenged with LPS in vitro. We found that TPPU reduced LPS-induced TREM-1 expression in a dose-dependent manner, but not DAP12 or MyD88 expression. TPPU also decreased downstream signal from TREM-1, reducing pro-inflammatory cytokine TNF-α and IL-1β mRNA expression. Furthermore, TPPU treatment inhibited IkB degradation in vivo and in vitro. Our results indicate that the inhibition of sEH suppresses LPS-induced TREM-1 expression and inflammation via inhibiting NF-kB activation in murine macrophage.

Blocking triggering receptor expressed on myeloid cells-1 attenuates lipopolysaccharide-induced acute lung injury via inhibiting NLRP3 inflammasome activation

Acute lung injury (ALI) is associated with high mortality and uncontrolled inflammation plays a critical role in ALI. TREM-1 is an amplifier of inflammatory response, and is involved in the pathogenesis of many infectious diseases. NLRP3 inflammasome is a member of NLRs family that contributes to ALI. However, the effect of TREM-1 on NLRP3 inflammasome and ALI is still unknown. This study aimed to determine the effect of TREM-1 modulation on LPS-induced ALI and activation of the NLRP3 inflammasome. We showed that LR12, a TREM-1 antagonist peptide, significantly improved survival of mice after lethal doses of LPS. LR12 also attenuated inflammation and lung tissue damage by reducing histopathologic changes, infiltration of the macrophage and neutrophil into the lung, and production of the pro-inflammatory cytokine, and oxidative stress. LR12 decreased expression of the NLRP3, pro-caspase-1 and pro-IL-1β, and inhibited priming of the NLRP3 inflammasome by inhibiting NF-κB. LR12 also reduced the expression of NLRP3 and caspase-1 p10 protein, and secretion of the IL-1β, inhibited activation of the NLRP3 inflammasome by decreasing ROS. For the first time, these data show that TREM-1 aggravates inflammation in ALI by activating NLRP3 inflammasome, and blocking TREM-1 may be a potential therapeutic approach for ALI.

TGF-β1 Upregulates the Expression of Triggering Receptor Expressed on Myeloid Cells 1 in Murine Lungs

Triggering receptor expressed on myeloid cells 1 (TREM-1) increases the expression of TGF-β family genes, which are known as profibrogenic cytokines in the pathogenesis of pulmonary fibrosis. In this study, we determined whether TGF-β1 regulated the expression of TREM-1 in a mouse model of pulmonary fibrosis. The expression of TGF-β1 and TREM-1 was increased on day 7, 14, and 21 after single intratracheal injection of bleomycin (BLM). And there was positive correlation between the expression of TGF-β1 and TREM-1. TGF-β1 increased expression of TREM-1 mRNA and protein in a time- and dose-dependent manner in mouse macrophages. The expression of the activator protein 1 (AP-1) was increased in lung tissues from mouse after BLM injection and in mouse macrophages after TGF-β1 treatment, respectively. TGF-β1 significantly increased the relative activity of luciferase in the cells transfected with plasmid contenting wild type-promoter of TREM-1. But TGF-β1 had no effect on the activity of luciferase in the cells transfected with a mutant-TREM1 plasmid carrying mutations in the AP-1 promoter binding site. In conclusion, we found the expression of TREM-1 was increased in lung tissues from mice with pulmonary fibrosis. TGF-β1 increased the expression of TREM-1 in mouse macrophages partly via the transcription factor AP-1.

Ginkgolide B Reduces the Degradation of Membrane Phospholipids to Prevent Ischemia/Reperfusion Myocardial Injury in Rats

Platelet-activating factor (PAF), a bioactive phospholipid, plays an important role in the integrity of the cellular membrane structure, and is involved in the pathogenesis of myocardial ischemia/reperfusion (IR) injuries. In this study, we tested the hypothesis that blockage of PAF receptor by BN 52021 (Ginkgolide B) can prevent IR-induced degradation of the myocardial membrane phospholipid, and deterioration of the cardiac function. Rat hearts in situ were subjected to 5 min ischemia and followed by 10 min reperfusion. Cardiac performances during periods of ischemia and reperfusion were monitored, and the amount of membrane phospholipids was analyzed. Myocardial total phospholipids, phosphatidylcholine, and phosphatidylethanolamine were decreased significantly in ischemia-reperfusion rat hearts compared with those of sham-operated rat hearts. Degradation of the membrane phospholipid was accompanied by the deterioration of cardiac functions and increase in serum lactate dehydrogenase (LDH) activity. BN 52021 (15 mg/kg), given by intravenous infusion 10 min prior to the left anterior descending coronary artery occlusion, reduced IR-related degradation of the myocardial phospholipids, the activity of serum LDH, and was concomitant with improvement of cardiac function. Furthermore, we demonstrated that the production of PAF was increased and BN 52021 decreased cellular damage in cultured anoxic cardiomyocytes. These results indicated that PAF antagonist BN 52021 has a protective effect against IR-induced myocardial dysfunction and degradation of the membrane phospholipids.

Vasoactive intestinal peptide suppresses macrophage-mediated inflammation by downregulating interleukin-17A expression via PKA- and PKC-dependent pathways

Interleukin (IL)-17A is a pro-inflammatory cytokine that markedly enhances inflammatory responses in the lungs by recruiting neutrophils and interacting with other pro-inflammatory mediators. Reducing the expression of IL-17A could attenuate inflammation in the lungs. However, whether VIP exerts its anti-inflammatory effects by regulating the expression of IL-17A has remained unclear. Here, we show that there is a remarkable increase of IL-17A in bronchoalveolar lavage fluid (BALF) and lung tissue of mice with acute lung injury (ALI). Moreover, lipopolysaccharides (LPS) stimulated elevated expression of IL-17A, which was evident by the enhanced levels of mRNA and protein observed. Furthermore, we also found that VIP inhibited LPS-mediated IL-17A expression in a time- and dose-dependent manner in an in vitro model of ALI and that this process might be mediated via the phosphokinase A (PKA) and phosphokinase C (PKC) pathways. Taken together, our results demonstrated that VIP might be an effective protector during ALI by suppressing IL-17A expression.

Calcitonin gene-related peptide promotes the wound healing of human bronchial epithelial cells via PKC and MAPK pathways

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide derived from the calcitonin gene. CGRP is widely distributed in the central and peripheral neuronal systems. In the lung, CGRP could modulate dendritic cell function, stimulate proliferation of alveolar epithelial cells and mediate lung injury in mice. In this study, we investigated the effect of CGRP on the wound healing of human bronchial epithelial cells (HBECs) in vitro. The results showed that CGRP accelerated the recovery of wound area of monolayer HBECs in a dose-dependent manner. CGRP inhibited the lipopolysaccharide-induced apoptosis in HBECs. The percentage of S phase and G2/M phase was increased in HBECs after CGRP treatment. CGRP upregulated the expression of Ki67 in a dose-dependent manner. Some pathway inhibitors were used to investigate the signal pathway in which CGRP was involved. We found out that PKC pathway inhibitor (H-7) and MAPK pathway inhibitor (PD98059) could partially attenuate the effect of CGRP, which indicated that CGRP might promote the wound healing of HBECs via PKC and/or MAPK dependent pathway by accelerating migration and proliferation, and inhibiting apoptosis.

[Effects of CGRP on the E-cadherin expression in human bronchial epithelial cells]

OBJECTIVE

To discuss the effect of calcitonin gene-related peptides (CGRP) on epithelial cadherin (E-cd) expression in human bronchial epithelial cells (HBECs) in vitro.

METHODS

The effect of CGRP on E-cd protein and mRNA expression in both normal and O3-challenged HBECs were determined by immunocytochemistry and RT-PCR. The signal transduction pathways of CGRP were observed by using protein kinase C(PKC) inhibitor (H-7), calmodulin(CaM) inhibitor (W-7) and PKA inhibitor (H-89).

RESULTS

CGRP increased E-cd mRNA and protein expressions of normal and O3-challenged HBECs in a dose-dependent manner. CGRP had no effect on cytoplasm E-cd expression. Pre-treatment with H-89, H-7 and W-7, the up-regulatory effect of CGRP on E-cd expression was partly abolished.

CONCLUSION

CGRP increased in cytomembrane E-cd expression of normal and O3-challenged HBECs in a dose-dependent manner. E-cd expression on HBECs was strengthened by CGRP via PKA, PKC and CaM pathways.

Role of c-fos gene in vasoactive intestinal peptide promoted synthesis of pulmonary surfactant phospholipids

We previously reported that vasoactive intestinal peptide (VIP) promoted synthesis of phosphatidylcholine (PC) in alveolar type II (ATII) cells. But the intracellular mechanism for this effect was unknown. In this work, we investigated the intracellular signal transduction pathway for VIP promoted synthesis of PC, the major lipid component of pulmonary surfactant (PS), by using an antagonist of VIP receptors, inhibitor of protein kinase C (PKC) and antisense oligonucleotides (AS-ODN) for c-fos oncogene. Our results showed that: 1 in circle [D-P-Cl-Phe(6)-Leu(17)]-VIP (10(-6) mol/l), an antagonist of VIP receptors, could decrease the quantity of [(3)H] choline incorporation, microsomal choline-phosphate cytidylyltransferase (CCT) mRNA expression and CCT activity induced by VIP (10(-8) mol/l) in cultured lung explants to the control levels; 2 in circle VIP (10(-8) mol/l) upregulated c-Fos protein expression in ATII cells. AS-ODN for c-fos oncogene (9x10(-6) mol/l) could block the elevation of [(3)H] choline incorporation, microsomal CCT mRNA expression and CCT activity induced by VIP in cultured lung explants and in ATII cells; 3 in circle H7 (10(-5) mol/l), a PKC inhibitor could also reduce VIP induced [(3)H] choline incorporation, microsomal CCT mRNA expression and CCT activity in cultured lung explants and in ATII cells. These results demonstrated that VIP receptors, PKC and c-Fos protein played important roles in the signaling pathway through which VIP promoted the synthesis of PC.

Vasoactive intestinal peptide enhances wound healing and proliferation of human bronchial epithelial cells

In the present study, we investigated the effects of vasoactive intestinal peptide (VIP) on wound healing of bronchial epithelium. Wound healing of the mechanical damaged human bronchial epithelial cells (HBEC) was observed in the absence or presence of VIP. Effects of VIP on chemotactic migration, cell proliferation of HBEC were also tested. HBEC chemotaxis was assessed by the blind well chamber technique, the cell cycle was determined by flow cytometry, and cell proliferation was determined by measuring the expression of proliferating cell nuclear antigen Ki67. Effects of VIP on epithelial E-cadherins protein and mRNA were also measured by immunohistochemistry and RT-PCR. The results showed that VIP accelerated the recovery of wound area of HBEC. VIP increased the migration and proliferation of HBEC, and these effects were blocked by a VPAC1 receptor antagonist. VIP also increased the expression of E-cadherin mRNA and protein in HBEC, suggesting that protective effects of VIP on wound healing may be related to its ability to increase the expression of E-cadherin. In conclusion, VIP has protective effects against human bronchial epithelial cell damage, and the beneficial effects of VIP might be mediated, at least in part, by VPAC1, and associated with increased expression of E-cadherin.

[Fibronectin upregulates catalase gene expression in rabbit bronchial epithelial cells]

We have previously shown that the binding of integrins with extracellular matrix component fibronectin (Fn) can improve the ability of bronchial epithelial cells (BECs) in resisting oxidant injury by up-regulating the activity of catalase and increasing the content of GSH. However, the molecular mechanism or its signaling pathway of this protection is still unclear. In order to examine the intracellular signaling mechanism activated by Fn-integrin binding reaction, the present study investigated the mRNA expression of catalase in primary cultured rabbit BECs using RT-PCR based on a cell-injury model made with ozone exposure. The product bands of target gene CAT were checked with Southern blot and oligonucleotide probe hybridization. The results showed that Fn (10 microg/ml) promoted the catalase mRNA transcription (P<0.01). This effect was abolished either by protein-tyrosine kinase inhibitor genistein or calmodulin inhibitor W(7) (P<0.01). These results indicate that the promotion of catalase activity induced by Fn-integrin reaction is partly due to the elevation of catalase mRNA transcription, and that its signalling are possibly relevant to tyrosine phosphorylation or calmodulin pathway.

Temporal and spatial distribution of VIP, CGRP and their receptors in the development of airway hyperresponsiveness in the lungs

To explore the role of intrapulmonary neuropeptides in the development of airway hyperresponsiveness, we established an animal model of airway hyperresponsiveness (AHR) in rabbits by using ozone exposure. With the model, after test of the mechanics of respiration and bronchoalveolar lavage assay, the levels of vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) in the lungs were determined by radioimmunoassay, and the expression of mRNA coding receptors of these two neuropeptides was evaluated by reverse transcriptional-polymerase chain reaction (RT-PCR). At the same time, the distribution of VIP receptor-1 (VIPR1) and CGRP receptor-1 (CGRPR1) in lung tissues and its time-course were examined by in situ hybridization. The results showed: (1) in ozone-stressing groups, airway resistance increased significantly and typical inflammatory pathological changes were observed in pulmonary tissue slides, including neutrophil and eosinophil infiltration, mucus exudation and bronchial epithelial cells (BECs) shedding; (2) with elongation of ozone exposure, the levels of VIP and CGRP in the lungs increased at first, reaching a peak on d 2 to 4, then decreased slowly, and CGRP peaked somewhat earlier than VIP; (3) mRNA expression of the two neuropeptide receptors in the lungs changed in a similar manner like VIP and CGRP, but the high level of mRNA expression of VIPR1 lasted longer than that of CGRPR1; and (4) in situ hybridization for neuropeptide receptors demonstrated that, in unstressed control, VIPR1 and CGRPR1 positive cells appeared in the airway epithelium, pulmonary interstitial and focal areas of airway and vascular smooth muscles. With the elongation of ozone exposure, hybridization stained deeper and the majority of positive cells were located around the vessels and bronchus except a few in the alveoli. At 8 d, only a small number of positive cells were seen in the lungs. From the results, it is concluded that ozone-stressing can induce the development of AHR, in which VIP and CGRP may play important roles. That implies, through binding to CGRPR1, CGRP stimulates an early inflammation response which contributes in cleaning up of irritants, while VIP exerts a later dampening of pulmonary inflammation response. These two neuropeptides may play sequential and complementary roles in the development of AHR.

Regulatory peptides modulate ICAM-1 gene expression and NF-kappaB activity in bronchial epithelial cells

Intercellular adhesion molecule-1 (ICAM-1) is an important adhesion molecule leading to adhesion between cells; NF-kappaB, being universally distributed in the organism, is an important nuclear transcription factor leading to a rapid response to the stimuli. Line of evidence have shown that ICAM-1 transcription and NF-kappaB activation is an important step of inflammatory reaction. To testify that intrapulmonary regulatory peptides modulate inflammatory lesion of bronchial epithelial cells (BECs) through their effect on ICAM-1 expression and nuclear factor kappaB (NF-kappaB) activation, we used immunocytochemistry, RT-PCR, and electrophoretic mobility-shift assay (EMSA) to determine the ICAM-1 expression and NF-kappaB activity in BECs. The effects of NF-kappaB inhibitor MG-132 on ICAM-1 expression were also observed. The results showed that vasoactive intestinal peptide (VIP) and epidermal growth factor (EGF) decreased ICAM-1 expression in O(3)-stressed BECs, while endothelin-1 (ET-1) and calcitonin gene-related peptides (CGRP) increased ICAM-1 expression in resting BECs. MG-132 blocked ICAM-1 expression induced by O(3), ET-1 and CGRP. The results obtained by using EMSA confirmed that VIP and EGF restrained the activation of NF-kappaB in O(3)-stressed BECs; CGRP and ET-1 promoted activation of NF-kappaB. These observations indicate that VIP and EGF abated the injury by means of down-regulatory effects on ICAM-1 transcription and NF-kappaB activation, while ET-1 and CGRP enhanced the inflammation reaction by an up-regulatory effect. It is suggested that a developing and intensive airway inflammation correlates closely with a persistent expression of ICAM-1 and repeated activation of NF-kappaB.

[Effect of 17beta-estradiol on phosphorylcholine cytidylyltransferase activity from cultured rat lung explants]

AIM

To investigate the influence and mechanisms of 17beta-estradiol on the CTP: phosphorylcholine cytidylyltransferase (CCT) activity from cultured lung explants without serum.

METHODS

We detected the amount of [M-14C] choline incorporation into phosphatidylcholine so as to reflect CCT activity by liquid scintillation.

RESULTS

(1) 17beta-estradiol increased the CCT activity in dose-dependence and time-dependence. (2) Both the protein kinase C inhibitor H-7 and calmodulin antagonist W-7 abolished the stimulatory effect of 17beta-estradiol (3 x 10(-6) mol/L) on the CCT activity.

CONCLUSION

17beta-estradiol can increase CCT activity in cultured lung explants, its mechanism is related to protein kinase C and calmodulin.

[Effect of sex hormones on secretion of lysozyme in alveolar macrophage]

AIM AND METHODS

To further explore the functions of alveolar macrophage and their modulation mechanisms, the activity of lysozyme in rat alveolar macrophage assessed by electrophoresis was determined. The effects of androsterone and estradiol on lysozyme secretion and their mechanisms were also studied.

RESULTS

The results showed that androsterone and estradiol increased activity of lysozyme significantly (P < 0.01), indomethacin abolished those effects. This suggests that the insufficiency of sex hormones secretion as the retrogression of gonads is involved in the decrease of immunological functions, and the susceptibility to infectious diseases.

CONCLUSION

Sex hormones increased activity of lysozyme, and those effects related to prostaglandin.

[Effects of vasoactive intestinal peptide on chemotaxis of bronchial epithelial cells]

To investigate the influence of vasoactive intestinal peptide (VIP) on chemotaxis of bronchial epithelial cells (BECs). Rabbit chemotactic migration of primary BEC was assessed in a blind-well Boyden chamber. Radioimmunoassay and radio-ligand affinity analysis were used for determining VIP secretion and vasoactive intestinal peptide receptor (VIPR) expression. The results showed: (1) the method for determining chemotaxis of BECs by using insulin as chemotactic factor was stable and reproducible (r=0.9703, P<0.01). (2) VIP (0.001-1 micromol/L) elicited chemotaxis of BECs which was substantial and concentration-dependent. The effects of VIP were inhibited by W-7 and H-7 (P<0.01). (3) Heat stress enhanced the secretion of VIP (P<0.01) and upregulated the expression of VIPR on BECs (P<0.05). These results indicate that VIP in the lungs may play an important role in the repair of damaged epithelium, accelerating restoration of the airway to its normal state. Calmodulin and protein kinase C may be involved in the signal transduction of VIP effects.

[Influence of regulatory peptides on the secretion of interleukins from bronchial epithelial cells of the rabbit]

To explore the role of regulatory peptides in the secretion of bronchial epithelial cells (BECs), we observed the effects of four peptides, i.e.vasoactive intestinal peptide (VIP), epidermal growth factor (EGF), endothelin-1 (ET-1), and calcitonin gene-related peptide (CGRP), on the secretion of ILs from unstimulated or O3-stressed BECs. The results of the experiments showed that VIP exerted an inhibitory effect on the secretion of IL-1 and IL-8 from unstimulated and O3-stressed BECs, VIP also decreased the secretion of IL-5 from O3-stressed BECs; EGF promoted secretion of IL-1 and IL-8 from unstimulated BECs, but decreased the secretion of ILs from O3-stressed BECs; ET-1 and CGRP enhanced the secretion of IL-1, IL-5, and IL-8 from unstimlated BECs, CGRP also increased the secretion of ILs from O3-stressed BECs. The results obtained demonstrate that intrapulmonary regulatory peptides modulate the secretion of ILs from BECs, and may play an important part in transduction of inflammatory signals.

[Effects of regulatory peptides on adhesion of eosinophil to bronchial epithelial cells]

To explore the roles of regulatory peptides in the process of various anaphylactic inflammation of the airway, we observed the influence of four peptides, i.e., vasoactive intestinal peptide (VIP), epidermal growth factor (EGF), endothelin-1 (ET-1), and calcitonin gene-related peptide (CGRP), on the adhesion of eosinophil (EOS) to unstimulated and O(3)-stressed bronchial epithelial cells (BEC). From the experiments we observed that VIP and EGF decreased EOS adherence to O(3)-stressed BEC and downregulated airway inflammation; ET-1 and CGRP increased the adhesion of EOS to BEC in the inflammatory process; and CGRP aggravated O(3)-stressed reactions. The effects of ET-1 and CGRP were inhibited by W(7)and H(7). Anti-ICAM-1 antibody inhibited the adhesion of EOS to BEC, which brings to light that EOS adherence to BEC may be related to the expression of ICAM-1 of BEC.

[Resisting injury and protective effect of fibronectin on bronchial epithelial cells]

AIM AND METHODS

To test the hypothesis that activation of integrin molecules play a role on protecting bronchial epithelial cells (BEC) from oxidant injury. Based on a cell-injury model made by ozone (1.5 x 10(-6)) exposure, the present study investigated the protective effect of fibronectin (Fn), a kind of ligand of integrin, and it's specific sequence Arg-Gly-Asp (RGD peptide) which is a recognizable domain for integrin on BEC. 3H release, LDH and MDA were measured as indexes for damage.

RESULTS

(1) Ozone exposure induced a significant increase of 3H release and LDH release from BEC and elevation of MDA. (2) Pretreatment with Fn or RGD before ozone exposure markedly attenuated the release of 3H, LDH and MDA, and the effects of Fn were reversed by W7, a calmodulin inhibitor. (3) Either Fn or RGD up-regulated activity of catalase in BEC and promoted GSH synthesis in BEC.

CONCLUSION

These suggests that the binding of integrin with Fn improve the antioxidant ability of BEC and lighten the damage induced by oxidant attack. The protective mechanism of Fn-integrin binding may be related with calmodulin.

[Integrin-ligands binding reaction upregulates the antioxidant activity of rabbit bronchial epithelial cells]

Antioxidant activity of bronchial epithelial cells (BECs) plays an essential role in preventing the airway epithelium integrity from damage in structure and function. Integrin expressed by BECs is the receptor of extracellular matrix such as fibronectin (Fn), and it is involved in modulation of proliferation, differentiation and metabolism of the cells. In order to test the hypothesis that integrin-ligand binding reaction supports the ability of cells to withstand oxidant attack, the present study evaluated the antioxidant activity of primary cultured rabbit BECs treated with fibronectin or its sequence Arg-Gly-Asp (RGD peptide), by determining changes in the activity of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) and in the level of glutathione (GSH). The results are as follows: (1) Fn (10 micrograms/ml) increased significantly the activity unit of GSH-Px (P < 0.05, n = 5), which was inhibited by calmodulin-inhibitor W7 (10(-5) mol/L) (P < 0.05). Both Fn (5-20 micrograms/ml) and RGD (15-60 micrograms/ml) showed a dose-dependent upregulatory effect (respectively r = 0.93 and r = 0.73). (2) Treatment with Fn increased SOD activity (P < 0.01, n = 7), which was abolished by W7 (P < 0.01). (3) Catalase activity was also stimulated by Fn (P < 0.05, n = 6) and reversed by W7 (P < 0.01). (4) A dose-dependent increase of GSH level was observed in both Fn (r = 0.82) and RGD treatment (r = 0.84). The data suggest that the binding of integrin with extracellular matrix can upregulate activity of antioxidant enzymes, and increase the content of GSH and improve the ability of BECs to resist oxidant injury.

[Cytoprotective effect of epidermal growth factor on cultured rabbit airway epithelial cells exposed to ozone]

In this study, it was observed that ozone (O3) exposure has cytotoxic effects on cultured airway epithelial cells, which was positively related with exposure duration. Both the production of malondialdehyde (MDA) and the 3H release in the exposure group were much higher than the control (P < 0.01), suggesting that lipoperoxidation occurring in the cell membrane was responsible for the cellular injury observed under O3 attack. EGF at low concentration (5 ng/ml) showed cytoprotective effect on airway epithelial cells exposed to O3 as shown by attenuated MDA production and decrease of 3H release and cytotoxic index (P < 0.01). Pretreatment with EGF could reverse the depletion of intracellular GSH content as a result of O3 exposure and increase the total glutathionein the cells. The above results suggest that the cytoprotection of EGF on airway epithelial cells may be related to its promotive effect on GSH synthesis.