Developmental differences in focal adhesion kinase expression modulate pulmonary endothelial barrier function in response to inflammation

Catalpol ameliorates liver fibrosis via inhibiting aerobic glycolysis by EphA2/FAK/Src signaling pathway

BACKGROUND

Hepatic fibrosis is a pathological process in a variety of acute or chronic liver injuries. Catalpol (CAT), an iridoid glycoside found in Rehmannia glutinosa, has several pharmacological properties, including anti-inflammatory, antidiabetic and anti-fibrotic effects. Nevertheless, there is currently no report on whether CAT regulates the aerobic glycolysis of hepatic stellate cells (HSCs) to inhibit liver fibrosis.

OBJECTIVE

This study aimed to investigate the protective effects of CAT on hepatic fibrosis and elucidate its underlying mechanisms.

METHODS

To explore whether CAT improved liver fibrosis in vivo and in vitro, hepatic fibrosis was induced to mice by intraperitoneally injecting carbon tetrachloride (CCl4). Additionally, LX-2 cells were stimulated with transforming growth factor-β (TGF-β) to simulate fibrosis in vitro. Serum markers of liver injury were examined by using an automatic biochemical analyzer. Histopathological staining, Immunofluorescence (IF) staining, Western blot (WB) analysis, co-immunoprecipitation (Co-IP), drug affinity responsive target stability (DARTS), cellular thermal shift assay (CETSA), etc. were employed to identify the targeting between CAT and EphA2 and detect the expression of aerobic glycolysis related proteins, fiber markers and signaling pathways that are responsible for CAT's anti-fibrotic effects of CAT.

RESULTS

Results showed that CAT significantly inhibited hepatic injury, fibrogenesis and inflammation in mice treated with CCl4. This was demonstrated by the enhancement of fibrosis markers, liver function indices, and histopathology. In addition, CAT significantly inhibited the activation of HSCs in TGF-β-induced LX-2 cells, as indicated by decreased proliferation, migration, and expression of collagen I and a-SMA. The study results also suggested that CAT may exert anti-fibrotic effects by inhibiting glycolysis in activated HSCs and in CCl4-treated mice. Mechanistically, CAT directly targets Ephrin type-A receptor 2 (EphA2) to reduce binding with focal adhesion kinases (FAK) and significantly inhibits the FAK/Src pathway. In addition, the pharmacological inhibition of EphA2 cannot further increase the therapeutic effects of CAT on liver fibrosis in vivo and in vitro.

CONCLUSION

The study findings generally demonstrated that CAT presented a novel therapeutic method to treat hepatic fibrosis; this method which inhibits the aerobic glycolysis of activated HSCs through the EphA2/FAK/Src signaling pathway.

FAK regulates tension transmission to the nucleus and endothelial transcriptome independent of kinase activity

The mechanical environment generated through the adhesive interaction of endothelial cells (ECs) with the matrix controls nuclear tension, preventing aberrant gene synthesis and the transition from restrictive to leaky endothelium, a hallmark of acute lung injury (ALI). However, the mechanisms controlling tension transmission to the nucleus and EC-restrictive fate remain elusive. Here, we demonstrate that, in a kinase-independent manner, focal adhesion kinase (FAK) safeguards tension transmission to the nucleus to maintain EC-restrictive fate. In FAK-depleted ECs, robust activation of the RhoA-Rho-kinase pathway increased EC tension and phosphorylation of the nuclear envelope protein, emerin, activating DNMT3a. Activated DNMT3a methylates the KLF2 promoter, impairing the synthesis of KLF2 and its target S1PR1 to induce the leaky EC transcriptome. Repleting FAK (wild type or kinase dead) or inhibiting RhoA-emerin-DNMT3a activities in damaged lung ECs restored KLF2 transcription of the restrictive EC transcriptome. Thus, FAK sensing and control of tension transmission to the nucleus govern restrictive endothelium to maintain lung homeostasis.

COVID-19 Disease in Under-5 Children: Current Status and Strategies for Prevention including Vaccination

Since the coronavirus disease (COVID-19) pandemic hit the globe in early 2020, we have steadily gained insight into its pathogenesis; thereby improving surveillance and preventive measures. In contrast to other respiratory viruses, neonates and young children infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have a milder clinical presentation, with only a small proportion needing hospitalization and intensive care support. With the emergence of novel variants and improved testing services, there has been a higher incidence of COVID-19 disease reported among children and neonates. Despite this, the proportion of young children with severe disease has not increased. Key mechanisms that protect young children from severe COVID-19 disease include the placental barrier, differential expression of angiotensin-converting enzyme 2 (ACE-2) receptors, immature immune response, and passive transfer of antibodies via placenta and human milk. Implementing mass vaccination programs has been a major milestone in reducing the global disease burden. However, considering the lower risk of severe COVID-19 illness in young children and the limited evidence about long-term vaccine safety, the risk-benefit balance in children under five years of age is more complex. In this review, we do not support or undermine vaccination of young children but outline current evidence and guidelines, and highlight controversies, knowledge gaps, and ethical issues related to COVID-19 vaccination in young children. Regulatory bodies should consider the individual and community benefits of vaccinating younger children in their local epidemiological setting while planning regional immunization policies.

Long-Term Consequences of Asymptomatic SARS-CoV-2 Infection: A Systematic Review and Meta-Analysis

Little is known about the long-term consequences of asymptomatic infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to review the data available to explore the long-term consequences of asymptomatic SARS-CoV-2 infection in the real world. We searched observational cohort studies that described the long-term health effects of asymptomatic SARS-CoV-2 infections. Random-effects inverse-variance models were used to evaluate the pooled prevalence (PP) and its 95% confidence interval (CI) of long-term symptoms. Random effects were used to estimate the pooled odds ratios (OR) and its 95%CI of different long-term symptoms between symptomatic and asymptomatic infections. Five studies involving a total of 1643 cases, including 597 cases of asymptomatic and 1043 cases of symptomatic SARS-CoV-2 infection were included in this meta-analysis. The PPs of long-term consequences after asymptomatic SARS-CoV-2 infections were 17.13% (95%CI, 7.55−26.71%) for at least one symptom, 15.09% (95%CI, 5.46−24.73%) for loss of taste, 14.14% (95%CI, −1.32−29.61%) for loss of smell, and 9.33% (95%CI, 3.07−15.60) for fatigue. Compared with symptomatic SARS-CoV-2 infection, asymptomatic infection was associated with a significantly lower risk of developing COVID-19-related sequelae (p < 0.05), with 80% lower risk of developing at least one symptom (OR = 0.20, 95%CI, 0.09−0.45), 81% lower risk of fatigue (OR = 0.19, 95%CI, 0.08−0.49), 90% lower risk of loss of taste/smell (OR = 0.10, 95%CI, 0.02−0.58). Our results suggested that there were long-term effects of asymptomatic SARS-CoV-2 infection, such as loss of taste or smell, fatigue, cough and so on. However, the risk of developing long-term symptoms in asymptomatic SARS-CoV-2 infected persons was significantly lower than those in symptomatic SARS-CoV-2 infection cases.

Dam-Infant Rhesus Macaque Pairs to Dissect Age-Dependent Responses to SARS-CoV-2 Infection

The global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated coronavirus disease (COVID-19) has led to a pandemic of unprecedented scale. An intriguing feature of the infection is the minimal disease in most children, a demographic at higher risk for other respiratory viral diseases. To investigate age-dependent effects of SARS-CoV-2 pathogenesis, we inoculated two rhesus macaque monkey dam-infant pairs with SARS-CoV-2 and conducted virological and transcriptomic analyses of the respiratory tract and evaluated systemic cytokine and Ab responses. Viral RNA levels in all sampled mucosal secretions were comparable across dam-infant pairs in the respiratory tract. Despite comparable viral loads, adult macaques showed higher IL-6 in serum at day 1 postinfection whereas CXCL10 was induced in all animals. Both groups mounted neutralizing Ab responses, with infants showing a more rapid induction at day 7. Transcriptome analysis of tracheal airway cells isolated at day 14 postinfection revealed significant upregulation of multiple IFN-stimulated genes in infants compared with adults. In contrast, a profibrotic transcriptomic signature with genes associated with cilia structure and function, extracellular matrix composition and metabolism, coagulation, angiogenesis, and hypoxia was induced in adults compared with infants. Our study in rhesus macaque monkey dam-infant pairs suggests age-dependent differential airway responses to SARS-CoV-2 infection and describes a model that can be used to investigate SARS-CoV-2 pathogenesis between infants and adults.

The Protective Effect of Artesunate on LPS-Induced Acute Respiratory Distress Syndrome through Inhibiting NLRP3 Inflammasome Signaling

Background

Artesunate (AS) is a derivative of artemisinin that can exert anti-inflammatory effects. This study aims to explore the effect of AS on lipopolysaccharide (LPS)-induced acute respiratory distress syndrome (ARDS).

Methods

The newborn mice were used for experimental ARDS model establishment by intraperitoneal injection of LPS (10 mg/kg) into mice with or without AS (20 mg/kg) pretreatment. After that, the pathological morphology of mouse lung tissue was observed by H&E staining. The content of inflammatory factors in serum was measured by ELISA and mRNA expression and lung tissue was determined by qRT-PCR. The expression of NLRP3 inflammasome and related proteins in lung tissue was confirmed by immunohistochemistry and Western blot.

Results

AS treatment effectively alleviated the LPS-induced lung injury and pulmonary edema, and reduced the expression of IL-1β, IL-18, IL-6, IL-8, MCP-1, and TNF-α in serum and lung tissues of experimental ARDS mice. In addition, AS treatment reduced the expression of NLRP3, ASC, and caspase-1 in lung tissues of experimental ARDS mice.

Conclusion

AS alleviated LPS-induced lung injury in ARDS mice by inhibiting the activation of NLRP3 inflammasome.

Adenovirus type 5 SARS-CoV-2 vaccines delivered orally or intranasally reduced disease severity and transmission in a hamster model

Transmission-blocking strategies that slow the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and protect against coronavirus disease 2019 (COVID-19) are needed. We have developed an orally delivered adenovirus type 5-vectored SARS-CoV-2 vaccine candidate that expresses the spike protein. Here, we demonstrated that hamsters vaccinated by the oral or intranasal route had robust and cross-reactive antibody responses. We then induced a postvaccination infection by inoculating vaccinated hamsters with SARS-CoV-2. Orally or intranasally vaccinated hamsters had decreased viral RNA and infectious virus in the nose and lungs and experienced less lung pathology compared to mock-vaccinated hamsters after SARS-CoV-2 challenge. Naïve hamsters exposed in a unidirectional air flow chamber to mucosally vaccinated, SARS-CoV-2-infected hamsters also had lower nasal swab viral RNA and exhibited fewer clinical symptoms than control animals, suggesting that the mucosal route reduced viral transmission. The same platform encoding the SARS-CoV-2 spike and nucleocapsid proteins elicited mucosal cross-reactive SARS-CoV-2-specific IgA responses in a phase 1 clinical trial (NCT04563702). Our data demonstrate that mucosal immunization is a viable strategy to decrease SARS-CoV-2 disease and airborne transmission.

Angiopoietin-1 protects against endotoxin-induced neonatal lung injury and alveolar simplification in mice

BACKGROUND

Sepsis in premature newborns is a risk factor for bronchopulmonary dysplasia (BPD), but underlying mechanisms of lung injury remain unclear. Aberrant expression of endothelial cell (EC) angiopoietin 2 (ANGPT2) disrupts angiopoietin 1 (ANGPT1)/TIE2-mediated endothelial quiescence, and is implicated in sepsis-induced acute respiratory distress syndrome in adults. We hypothesized that recombinant ANGPT1 will mitigate sepsis-induced ANGPT2 expression, inflammation, acute lung injury (ALI), and alveolar remodeling in the saccular lung.

METHODS

Effects of recombinant ANGPT1 on lipopolysaccharide (LPS)-induced endothelial inflammation were evaluated in human pulmonary microvascular endothelial cells (HPMEC). ALI and long-term alveolar remodeling were assessed in newborn mice exposed to intraperitoneal LPS and recombinant ANGPT1 pretreatment.

RESULTS

LPS dephosphorylated EC TIE2 in association with increased ANGPT2 in vivo and in vitro. ANGPT1 suppressed LPS and ANGPT2-induced EC inflammation in HPMEC. Neonatal mice treated with LPS had increased lung cytokine expression, neutrophilic influx, and cellular apoptosis. ANGPT1 pre-treatment suppressed LPS-induced lung Toll-like receptor signaling, inflammation, and ALI. LPS-induced acute increases in metalloproteinase 9 expression and elastic fiber breaks, as well as a long-term decrease in radial alveolar counts, were mitigated by ANGPT1.

CONCLUSIONS

In an experimental model of sepsis-induced BPD, ANGPT1 preserved endothelial quiescence, inhibited ALI, and suppressed alveolar simplification.

IMPACT

Key message: Angiopoietin 1 inhibits LPS-induced neonatal lung injury and alveolar remodeling. Additions to existing literature: Demonstrates dysregulation of angiopoietin-TIE2 axis is important for sepsis- induced acute lung injury and alveolar simplification in experimental BPD. Establishes recombinant Angiopoietin 1 as an anti-inflammatory therapy in BPD.

IMPACT

Angiopoietin 1-based interventions may represent novel therapies for mitigating sepsis-induced lung injury and BPD in premature infants.

Influence of Fucoidan Extracts from Different Fucus Species on Adult Stem Cells and Molecular Mediators in In Vitro Models for Bone Formation and Vascularization

Fucoidans, sulfated polysaccharides extracted from brown algae, are marine products with the potential to modulate bone formation and vascularization processes. The bioactivity and safety of fucoidans are highly associated with their chemical structure, which may vary with algae species and extraction method. Thus, in depth evaluation of fucoidan extracts in terms of endotoxin content, cytotoxicity, and their detailed molecular biological impact on the individual cell types in bone is needed. In this study, we characterized fucoidan extracts from three different Fucus species including Fucus vesiculosus (Fv), Fucus serratus (Fs), and Fucus distichus subsp. evanescens (Fe) for their chemical features, endotoxin content, cytotoxicity, and bioactive effects on human outgrowth endothelial cells (OEC) and human mesenchymal stem cells (MSC) as in vitro models for bone function and vascularization. Extracts contained mainly high molecular weight (HMW) fucoidans and were free of endotoxins that may cause inflammation or influence vascularization. OEC tolerated fucoidan concentrations up to 200 µg/mL, and no indication of cytotoxicity was observed. The inflammatory response, however, investigated by real-time PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) and endothelial barrier assessed by impedance measurement differed for the individual extracts. MSC in comparison with endothelial cells were more sensitive to fucoidans and showed partly reduced metabolic activity and proliferation at higher doses of fucoidans. Further results for MSC indicated impaired osteogenic functions in alkaline phosphatase and calcification assays. All tested extracts consistently lowered important molecular mediators involved in angiogenesis, such a VEGF (vascular endothelial growth factor), ANG-1 (angiopoietin 1), and ANG-2 (angiopoietin 2), as indicated by RT-PCR and ELISA. This was associated with antiangiogenic effects at the functional level using selected extracts in co-culture models to mimic bone vascularization processes during bone regeneration or osteosarcoma.

Understanding the age divide in COVID-19: why are children overwhelmingly spared?

The rapid emergence and subsequent global dissemination of SARS-CoV-2 disease (COVID-19) has resulted in over 4 million cases worldwide. The disease has a marked predilection for adults, and children are relatively spared. Understanding the age-based differences in pathophysiological pathways and processes relevant to the onset and progression of disease both in the clinical course and in experimental disease models may hold the key to the identification of therapeutic targets. The differences in the clinical course are highlighted by the lack of progression of the SARS-CoV-2 infection beyond mild symptoms in a majority of children, whereas in adults the disease progresses to acute lung injury and an acute respiratory distress syndrome (ARDS)-like phenotype with high mortality. The pathophysiological mechanisms leading to decreased lung injury in children may involve the decreased expression of the mediators necessary for viral entry into the respiratory epithelium and differences in the immune system responses in children. Specifically, decreased expression of proteins, including angiotensin-converting enzyme 2 (ACE2) and Transmembrane Serine Protease 2 (TMPRSS2) in the airway epithelium in children may prevent viral entry. The immune system differences may include a relative preponderance of CD4+ T cells, decreased neutrophil infiltration, decreased production of proinflammatory cytokines, and increased production of immunomodulatory cytokines in children compared with adults. Notably, the developing lung in children may have a greater capacity to recover and repair after viral infection. Understanding the relative contributions of the above processes to the protective phenotype in the developing lung can guide the trial of the appropriate therapies in adults.

Ibudilast, a Phosphodiesterase-4 Inhibitor, Ameliorates Acute Respiratory Distress Syndrome in Neonatal Mice by Alleviating Inflammation and Apoptosis

Background

Acute respiratory distress syndrome (ARDS) is a sudden and serious disease with increasing morbidity and mortality rates. Phosphodiesterase 4 (PDE4) is a novel target for inflammatory disease, and ibudilast (IBU), a PDE4 inhibitor, inhibits inflammatory response. Our study investigated the effect of IBU on the pathogenesis of neonatal ARDS and the underlying mechanism related to it.

Material/Methods

Western blotting was performed to analyze the expression levels of PDE4, CXCR4, SDF-1, CXCR5, CXCL1, inflammatory cytokines, and proteins related to cell apoptosis. Hematoxylin-eosin staining was performed to observe the pathological morphology of lung tissue. Pulmonary edema score was used to assess the degree of lung water accumulation after pulmonary injury. Enzyme-linked immunosorbent assay (ELISA) was used to assess levels of inflammatory factors (TNF-α, IL-1β, IL-6, and MCP-1) in serum. TUNEL assay was used to detect apoptotic cells.

Results

Increased expression of PDE4 was observed in an LPS-induced neonatal ARDS mouse model, and IBU ameliorated LPS-induced pathological manifestations and pulmonary edema in lung tissue. In addition, IBU attenuated the secretion of inflammatory cytokines by inactivating the chemokine axis in the LPS-induced neonatal ARDS mouse model. Finally, IBU significantly reduced LPS-induced cell apoptosis in lung tissue.

Conclusions

IBU, a PDE4 inhibitor, protected against ARDS by interfering with pulmonary inflammation and apoptosis. Our findings provide a novel and promising strategy to regulate pulmonary inflammation in ARDS.

Interleukin-37 Attenuates Lipopolysaccharide (LPS)-Induced Neonatal Acute Respiratory Distress Syndrome in Young Mice via Inhibition of Inflammation and Cell Apoptosis

Background

Neonatal acute respiratory distress syndrome (ARDS) is a common clinical syndrome caused by lung immaturity and the abnormal synthesis of pulmonary surfactant in preterm newborns, and it has high morbidity and mortality rates. The present study investigated the roles of interleukin-37 (IL-37) in the pathogenesis of neonatal ARDS and the underlying biochemical mechanism.

Material/Methods

We used 6-day-old neonatal C57BL/6 mice to establish the ARDS model. Inflammatory cytokines levels were measured with enzyme-linked immunosorbent assay (ELISA) Kits. The pathological morphology of lung tissues was observed by hematoxylin-eosin (HE) staining. The expression levels of proteins were assessed by Western blotting and apoptotic cells were detected via TUNEL assay. Further, the expression of nucleotide-bound oligomerization domain (Nod)-like receptor P3 (NLRP3) was detected with immunohistochemistry and Western blotting.

Results

IL-37 attenuated lipopolysaccharide (LPS)-induced cell apoptosis and excessive inflammatory cytokines levels, including IL-1β, IL-8, TNF-α, and MCP-1, and ameliorated lung pathological manifestations in an LPS-induced neonatal ARDS model. Moreover, IL-37 suppressed the abnormal expression of proteins related to the CXCR4/SDF-1 chemokine axis and NLRP3 inflammasome pathway.

Conclusions

The present results suggest that IL-37 protect against LPS-induced lung injury through inhibition of inflammation and apoptosis in lung tissue in an LPS-induced neonatal ARDS model. Hence, IL-37 may be considered as a potential therapeutic agent for neonatal ARDS.

Exosome-delivered syndecan-1 rescues acute lung injury via a FAK/p190RhoGAP/RhoA/ROCK/NF-κB signaling axis and glycocalyx enhancement

Acute lung injury (ALI) is characterized by protein-rich pulmonary edema, critical hypoxemia, and influx of pro-inflammatory cytokines and cells. There are currently no effective pharmacon therapies in clinical practice. Syndecan-1 in endothelial cells has potential to protect barrier function of endothelium and suppress inflammation response. Thus, the present study was to identify whether exosomes with encapsulation of syndecan-1 could achieve ideal therapeutic effects in ALI. Exosomes were isolated from the conditional medium of lentivirus-transfected mouse pulmonary microvascular endothelial cells (MPMVECs) and characterized by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and western blotting. ALI mouse models were induced via intratracheal administration of lipopolysaccharide (LPS) and treated with exosomes. Lung edema, inflammation, and glycocalyx thickness were examined. The possible mechanism was verified by immunoblotting in MPMVECs. The purified exosomes included SDC1-high-Exos and SDC1-low-Exos which loaded with up-regulated syndecan-1 and down-regulated syndecan-1 respectively. Compared with SDC1-low-Exos, administration of SDC1-high-Exos could ameliorate lung edema and inflammation, attenuate number of cells and protein levels in bronchoalveolar lavage fluid (BALF), and preserve glycocalyx. Furthermore, SDC1-high-Exos also mitigated the expression of pro-inflammatory cytokines such as IL-1β, TNF-α, and IL-6 following LPS challenge. In MPMVECs, SDC1-high-Exos decreased stress fiber formation and ameliorated monolayer hyper-permeability after LPS stimulation. Western blotting analysis demonstrated that FAK/p190RhoGAP/RhoA/ROCK/NF-κB signaling pathway may be involved in LPS-induced ALI. In conclusion, SDC1-high-Exos play a pivotal role in ameliorating LPS-stimulated ALI models and may be served as a potential therapeutic agent for clinical application in the future.

Cortical Actin Dynamics in Endothelial Permeability

The pulmonary endothelial cell forms a critical semi-permeable barrier between the vascular and interstitial space. As part of the blood-gas barrier in the lung, the endothelium plays a key role in normal physiologic function and pathologic disease. Changes in endothelial cell shape, defined by its plasma membrane, determine barrier integrity. A number of key cytoskeletal regulatory and effector proteins including non-muscle myosin light chain kinase, cortactin, and Arp 2/3 mediate actin rearrangements to form cortical and membrane associated structures in response to barrier enhancing stimuli. These actin formations support and interact with junctional complexes and exert forces to protrude the lipid membrane to and close gaps between individual cells. The current knowledge of these cytoskeletal processes and regulatory proteins are the subject of this review. In addition, we explore novel advancements in cellular imaging that are poised to shed light on the complex nature of pulmonary endothelial permeability.