GLP-1 Analogue Liraglutide Enhances SP-A Expression in LPS-Induced Acute Lung Injury through the TTF-1 Signaling Pathway

Liraglutide pretreatment attenuates sepsis-induced acute lung injury

There are no effective targeted therapies to treat acute respiratory distress syndrome (ARDS). Recently, the commonly used diabetes and obesity medications, glucagon-like peptide-1 (GLP-1) receptor agonists, have been found to have anti-inflammatory properties. We, therefore, hypothesized that liraglutide pretreatment would attenuate murine sepsis-induced acute lung injury (ALI). We used a two-hit model of ALI (sepsis+hyperoxia). Sepsis was induced by intraperitoneal injection of cecal slurry (CS; 2.4 mg/g) or 5% dextrose (control) followed by hyperoxia [HO; fraction of inspired oxygen ([Formula: see text]) = 0.95] or room air (control; [Formula: see text] = 0.21). Mice were pretreated twice daily with subcutaneous injections of liraglutide (0.1 mg/kg) or saline for 3 days before initiation of CS+HO. At 24-h post CS+HO, physiological dysfunction was measured by weight loss, severity of illness score, and survival. Animals were euthanized, and bronchoalveolar lavage (BAL) fluid, lung, and spleen tissues were collected. Bacterial burden was assessed in the lung and spleen. Lung inflammation was assessed by BAL inflammatory cell numbers, cytokine concentrations, lung tissue myeloperoxidase activity, and cytokine expression. Disruption of the alveolar-capillary barrier was measured by lung wet-to-dry weight ratios, BAL protein, and epithelial injury markers (receptor for advanced glycation end products and sulfated glycosaminoglycans). Histological evidence of lung injury was quantified using a five-point score with four parameters: inflammation, edema, septal thickening, and red blood cells (RBCs) in the alveolar space. Compared with saline treatment, liraglutide improved sepsis-induced physiological dysfunction and reduced lung inflammation, alveolar-capillary barrier disruption, and lung injury. GLP-1 receptor activation may hold promise as a novel treatment strategy for sepsis-induced ARDS. Additional studies are needed to better elucidate its mechanism of action.NEW & NOTEWORTHY In this study, pretreatment with liraglutide, a commonly used diabetes medication and glucagon-like peptide-1 (GLP-1) receptor agonist, attenuated sepsis-induced acute lung injury in a two-hit mouse model (sepsis + hyperoxia). Septic mice who received the drug were less sick, lived longer, and displayed reduced lung inflammation, edema, and injury. These therapeutic effects were not dependent on weight loss. GLP-1 receptor activation may hold promise as a new treatment strategy for sepsis-induced acute respiratory distress syndrome.

The relationship between the use of GLP-1 receptor agonists and the incidence of respiratory illness: a meta-analysis of randomized controlled trials

AIM

We aimed to assess the association between the use of Glucagon-like peptide-1 receptor agonists and the risk of 12 respiratory diseases in patients with type 2 diabetes, obesity, or overweight.

METHOD

The PubMed (MEDLINE), EMBASE, Cochrane Library, and ClinicalTrials.gov databases were searched from the establishment of the database to December 24, 2022. Dichotomous outcomes were analyzed using RR and 95% CI calculated from fixed-effects models.

RESULTS

Twenty-eight RCTs were ultimately included for analysis, involving a total of 77,485 participants. Compared to controls, patients with GLP-1RAs have a 14% lower risk of respiratory disease (RR 0.86, 95% CI 0.81-0.93 p < 0.0001), with Semaglutid (RR 0.82, 95% CI 0.68-0.97, p = 0.02), Liraglutide (RR 0.86. 95% CI 0.75-0.98, p = 0.03), Dulaglutide (RR 0.82, 95% CI 0.70-0.96, p = 0.02), Albiglutide (RR 0.93,95% CI 0.79-1.10, p = 0.40), Exenatide (RR 0.93, 95% CI 0.74-1.18, p = 0.55), Lixisenatide (RR 0.83, 95% CI 0.62-1.12, p = 0.22), and Efpeglenatide (RR 0.76, 95% CI 0.46-1.24, p = 0.27). Semaglutide, Liraglutide and Dulaglutide reduce the risk of respiratory diseases by 18%, 14% and 18%, respectively.Trial duration, control type, and indication were not associated with the impact of GLP-1 receptor agonists on overall respiratory disease. Among secondary outcomes, the risk of Pulmonary edema (RR 0.66, 95% CI 0.44-0.98, p = 0.04), and Bronchitis (RR 0.86, 95% CI 0.74-1.00, p = 0.04) was reduced.

CONCLUSION

In conclusion, GLP-1RAs were linked to a lower risk of overall respiratory diseases, especially Pulmonary edema and Bronchitis. In the future, physicians should pay attention to the relationship between GLP-1 RA and the risk of respiratory diseases and evaluate the efficacy of GLP-1RAs in the primary and secondary prevention of respiratory diseases. Trial registration CRD42023396138.

LncRNA CASC15 inhibition relieves renal fibrosis in diabetic nephropathy through down-regulating SP-A by sponging to miR-424

Study has demonstrated the abnormal expression and role of lncRNA CASC15 in diabetes patients with chronic renal failure. However, its role in diabetes nephropathy (DN) is still unclear. This study aimed to investigate the potential mechanism and role of lncRNA CASC15 in DN. The relationship between miR-424 and CASC15/SP-A was predicted by Starbase software and verified by luciferase reporter assay. HK-2 cells were treated with 25 mM glucose (HG) for 24 h to establish DN cell model. MTT and flow cytometry analysis were carried out to test cell proliferation and apoptosis. Epithelial-to-mesenchymal transition (EMT) markers were analyzed by RT-qPCR and western blot assay. We proved that CASC15 could interact with miR-424, and SP-A was a target of miR-424. HG-treatment significantly enhanced lncRNA CASC15 level and decreased miR-424 level in HK-2 cells. LncRNA CASC15-siRNA significantly improved cell viability, repressed apoptosis, promoted E-cadherin expression, and inhibited N-cadherin expression in HG-treated HK-2 cells, and these effects were reversed by miR-424 inhibitor. SP-A was highly expressed in HG-treated HK-2 cells. The biological effects of miR-424 mimic on HG-treated HK-2 cells were reversed by SP-A-plasmid. In conclusion, lncRNA CASC15 inhibition relieved HG-induced HK-2 cell injury and EMT through miR-424/SP-A axis.

Glucagon-like peptide-1: a multi-faceted anti-inflammatory agent

Inflammation contributes to many chronic conditions. It is often associated with circulating pro-inflammatory cytokines and immune cells. GLP-1 levels correlate with disease severity. They are often elevated and can serve as markers of inflammation. Previous studies have shown that oxytocin, hCG, ghrelin, alpha-MSH and ACTH have receptor-mediated anti-inflammatory properties that can rescue cells from damage and death. These peptides have been studied well in the past century. In contrast, GLP-1 and its anti-inflammatory properties have been recognized only recently. GLP-1 has been proven to be a useful adjuvant therapy in type-2 diabetes mellitus, metabolic syndrome, and hyperglycemia. It also lowers HbA1C and protects cells of the cardiovascular and nervous systems by reducing inflammation and apoptosis. In this review we have explored the link between GLP-1, inflammation, and sepsis.

Therapeutic Peptides for Treatment of Lung Diseases: Infection, Fibrosis, and Cancer

Various lung diseases endanger people's health. Side effects and pharmaceutical resistance complicate the treatment of acute lung injury, pulmonary fibrosis, and lung cancer, necessitating the development of novel treatments. Antimicrobial peptides (AMPs) are considered to serve as a viable alternative to conventional antibiotics. These peptides exhibit a broad antibacterial activity spectrum as well as immunomodulatory properties. Previous studies have shown that therapeutic peptides including AMPs had remarkable impacts on animal and cell models of acute lung injury, pulmonary fibrosis, and lung cancer. The purpose of this paper is to outline the potential curative effects and mechanisms of peptides in the three types of lung diseases mentioned above, which may be used as a therapeutic strategy in the future.

The anti-inflammatory feature of glucagon-like peptide-1 and its based diabetes drugs—Therapeutic potential exploration in lung injury

Since 2005, GLP-1 receptor (GLP-1R) agonists (GLP-1RAs) have been developed as therapeutic agents for type 2 diabetes (T2D). GLP-1R is not only expressed in pancreatic islets but also other organs, especially the lung. However, controversy on extra-pancreatic GLP-1R expression still needs to be further resolved, utilizing different tools including the use of more reliable GLP-1R antibodies in immune-staining and co-immune-staining. Extra-pancreatic expression of GLP-1R has triggered extensive investigations on extra-pancreatic functions of GLP-1RAs, aiming to repurpose them into therapeutic agents for other disorders. Extensive studies have demonstrated promising anti-inflammatory features of GLP-1RAs. Whether those features are directly mediated by GLP-1R expressed in immune cells also remains controversial. Following a brief review on GLP-1 as an incretin hormone and the development of GLP-1RAs as therapeutic agents for T2D, we have summarized our current understanding of the anti-inflammatory features of GLP-1RAs and commented on the controversy on extra-pancreatic GLP-1R expression. The main part of this review is a literature discussion on GLP-1RA utilization in animal models with chronic airway diseases and acute lung injuries, including studies on the combined use of mesenchymal stem cell (MSC) based therapy. This is followed by a brief summary.

Evaluating the glucagon-like peptide-1 receptor in managing asthma

PURPOSE OF REVIEW

The aim of this study was to discuss the role of glucagon-like peptide-1 (GLP-1) receptor signalling in reducing lung inflammation and potential use for GLP-1 receptor agonists (GLP-1RAs) in management of asthma.

RECENT FINDINGS

Although GLP-1RA are currently used for the treatment of type 2 diabetes (T2D) and weight loss in obesity, there is much interest in expanding the indications for use in other diseases, including inflammatory pulmonary disease. In animal models of both acute and chronic pulmonary disease, use of GLP-1RA reduces airway inflammation, obstruction and fibrosis. In particular, GLP-1 receptor (GLP-1R) signalling seems to inhibit allergen-induced type 2 inflammation, making it an attractive agent for asthma. Results are especially promising in disease processes with disturbed metabolic regulation, such as T2D or metabolic syndrome. Retrospective clinical studies demonstrate promising evidence for the use of GLP-1RAs in comorbid diabetes and asthma, although prospective human studies are limited.

SUMMARY

Here, we discuss the biology of GLP-1 and GLP-1R signalling, review the preclinical and mechanistic evidence for how GLP-1R signalling may reduce pulmonary inflammation, and summarize recent and upcoming clinical studies. Ultimately, targeting GLP-1R signalling may represent a novel approach for asthma therapy that is glucocorticoid sparing and possibly disease modifying.

Emodin protects against intestinal and lung injury induced by acute intestinal injury by modulating SP-A and TLR4/NF-κB pathway

Objective: Our aim was to investigate the effect of emodin on intestinal and lung injury induced by acute intestinal injury in rats and explore potential molecular mechanisms.

Methods: Healthy male Sprague–Dawley (SD) rats were randomly divided into five groups (n=10, each group): normal group; saline group; acute intestinal injury model group; model + emodin group; model+NF-κB inhibitor pynolidine dithiocarbamate (PDTC) group. Histopathological changes in intestine/lung tissues were observed by Hematoxylin and Eosin (H&E) and terminal deoxynucleotidyl transferase biotin-dUTP nick-end labeling (TUNEL) staining. Serum IKBα, p-IKBα, surfactant protein-A (SP-A) and toll-like receptor 4 (TLR4) levels were examined using enzyme-linked immunosorbent assay (ELISA). RT-qPCR was performed to detect the mRNA expression levels of IKBα, SP-A and TLR4 in intestine/lung tissues. Furthermore, the protein expression levels of IKBα, p-IKBα, SP-A and TLR4 were detected by Western blot.

Results: The pathological injury of intestinal/lung tissues was remarkedly ameliorated in models treated with emodin and PDTC. Furthermore, the intestinal/lung injury scores were significantly decreased after emodin or PDTC treatment. TUNEL results showed that both emodin and PDTC treatment distinctly attenuated the apoptosis of intestine/lung tissues induced by acute intestinal injury. At the mRNA level, emodin significantly increased the expression levels of SP-A and decreased the expression levels of IKBα and TLR4 in intestine/lung tissues. According to ELISA and Western blot, emodin remarkedly inhibited the expression of p-IKBα protein and elevated the expression of SP-A and TLR4 in serum and intestine/lung tissues induced by acute intestinal injury.

Conclusion: Our findings suggested that emodin could protect against intestinal and lung injury induced by acute intestinal injury by modulating SP-A and TLR4/NF-κB pathway.

Dysregulated Metabolism in the Pathophysiology of Non-Allergic Obese Asthma

Asthma is an obstructive airway disease that is characterized by reversible airway obstruction and is classically associated with atopic, T_H2 driven inflammation. Landmark studies in the second half of the twentieth century identified eosinophils as a key mediator of inflammation and steroids, both inhaled and systemic, as a cornerstone of therapy. However, more recently other phenotypes of asthma have emerged that do not respond as well to traditional therapies. In particular, obese patients who develop asthma as adults are less likely to have eosinophilic airway inflammation and do not respond to traditional therapies. Obese patients often have metabolic comorbidities such as impaired glucose tolerance and dyslipidemias, also known as metabolic syndrome (MetS). The unified pathophysiology of metabolic syndrome is not known, however, several signaling pathways, such as the neuropeptide glucagon-like peptide-1 (GLP-1) and nitric oxide (NO) signaling have been shown to be dysregulated in MetS. These pathways are targeted by commercially available medications. This review discusses the potential roles that dysregulation of the GLP-1 and NO signaling pathways, along with arginine metabolism, play in the development of asthma in obese patients. GLP-1 receptors are found in high density in the lung and are also detectable in bronchoalveolar lavage fluid. NO has long been associated with asthma. We hypothesize that these derangements in metabolic signaling pathways underpin the asthmatic phenotype seen in obese patients with non-eosinophilic airway inflammation and poor response to established therapies. While still an active area of research, novel interventions are needed for this subset of patient who respond poorly to available asthma therapies.

[MiR-600 suppresses HeLa cell proliferation by inhibiting hypoxia-inducible factor-1α signaling pathway]

OBJECTIVE

To determine whether miR-600 suppresses the proliferation of HeLa cells by inhibiting hypoxia-inducible factor-1α (HIF-1α) signaling pathway and its effect on expressions of cyclin D1 and vascular endothelial growth factor (VEGF).

OBJECTIVE

HeLa cells were transfected with miR-600 mimic and plasmid-HIF-1α, either alone or in combination, to up-regulate miR-600 and HIF-1α expressions in the cells. Six hours after the transfection, the cell viability was assessed using MTT assay, and the mRNA and protein expressions of VEGF, cyclin D1, and HIF-1α were analyzed with qPCR and Western blotting.

OBJECTIVE

The viability of HeLa cells showed no obvious changes 6 h after transfection with miR-600 mimic or Plasmid-HIF-1α. At 24 h and 48 h, the cells transfected with miR-600 mimic showed a time-dependent reduction of cell viability, while the cells transfected with Plasmid-HIF-1α alone and with both miR-600 mimic and Plasmid-HIF-1α showed increased cell viability. The cell viabilities in Plasmid-HIF-1α group were significantly higher than those in miR-600 mimic+Plasmid-HIF-1α group at 24 h and 48 h. Six hours after transfection with miR-600 mimic, the cells exhibited significantly decreased expressions of VEGF, cyclin D1, and HIF-1α, which were all significantly up-regulated in Plasmid-HIF-1α group and miR-600 mimic+Plasmid-HIF-1α group. VEGF, cyclin D1, and HIF-1α expressions were significant higher in Plasmid-HIF-1α group than in miR-600 mimic+ Plasmid-HIF-1α group.

OBJECTIVE

miR-600 suppresses the proliferation of HeLa cells and down-regulate the expressions of cyclin D1 and VEGF by inhibiting HIF-1α signaling pathway.

GLP-1 Receptor Signaling Differentially Modifies the Outcomes of Sterile vs Viral Pulmonary Inflammation in Male Mice

A number of disease states, including type 2 diabetes (T2D), are associated with an increased risk of pulmonary infection. Glucagon-like peptide-1 (GLP-1) receptor agonists are used to treat T2D and exert anti-inflammatory actions through a single, well-defined GLP-1 receptor (GLP-1R). Although highly expressed in the lung, little is known about the role of the GLP-1R in the context of pulmonary inflammation. Here we examined the consequences of gain or loss of GLP-1R activity in infectious and noninfectious lung inflammation. We studied wild-type mice treated with a GLP-1R agonist, and Glp1r-/- mice, in the setting of bleomycin-induced noninfectious lung injury and influenza virus infection. Loss of the GLP-1R attenuated the severity of bleomycin-induced lung injury, whereas activation of GLP-1R signaling increased pulmonary inflammation via the sympathetic nervous system. In contrast, GLP-1R agonism reduced the pathogen load in mice with experimental influenza virus infection in association with increased expression of intracellular interferon-inducible GTPases. Notably, the GLP-1 receptor agonist liraglutide improved the survival rate after influenza virus infection. Our results reveal context-dependent roles for the GLP-1 system in the response to lung injury. Notably, the therapeutic response of GLP-1R agonism in the setting of experimental influenza virus infection may have relevance for ongoing studies of GLP-1R agonism in people with T2D susceptible to viral lung injury.

Induced sputum metabolomic profiles and oxidative stress are associated with chronic obstructive pulmonary disease (COPD) severity: potential use for predictive, preventive, and personalized medicine

Chronic obstructive pulmonary disease (COPD) is a highly heterogeneous disease, and metabolomics plays a hub role in predictive, preventive, and personalized medicine (PPPM) related to COPD. This study thus aimed to reveal the role of induced sputum metabolomics in predicting COPD severity. In this pilot study, a total of 20 COPD patients were included. The induced sputum metabolites were assayed using a liquid chromatography-mass spectrometry (LC-MS/MS) system. Five oxidative stress products (myeloperoxidase (MPO), superoxide dismutase (SOD), glutathione (GSH), neutrophil elastase (NE), and 8-iso-PGF2α) in induced sputum were measured by ELISA, and the metabolomic profiles were distinguished by principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA). The Kyoto Encyclopedia of Genes and Genomes (KEGG) was used for pathway enrichment analysis, and a significant difference in induced sputum metabolomics was observed between moderate and severe COPD. The KEGG analysis revealed that the glycerophospholipid metabolism pathway was downregulated in severe COPD. Due to the critical role of glycerophospholipid metabolism in oxidative stress, significant negative correlations were discovered between glycerophospholipid metabolites and three oxidative stress products (SOD, MPO, and 8-iso-PGF2α). The diagnostic values of SOD, MPO, and 8-iso-PGF2α in induced sputum were found to exhibit high sensitivities and specificities in the prediction of COPD severity. Collectively, this study provides the first identification of the association between induced sputum metabolomic profiles and COPD severity, indicating the potential value of metabolomics in PPPM for COPD management. The study also reveals the correlation between glycerophospholipid metabolites and oxidative stress products and their value for predicting COPD severity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-020-00227-w.

Monocyte chemotactic protein-inducing protein 1 negatively regulating asthmatic airway inflammation and mucus hypersecretion involving γ-aminobutyric acid type A receptor signaling pathway in vivo and in vitro

BACKGROUND

Mounting evidence, consistent with our previous study, showed that γ-aminobutyric acid type A receptor (GABAAR) played an indispensable role in airway inflammation and mucus hypersecretion in asthma. Monocyte chemotactic protein-inducing protein 1 (MCPIP1) was a key negative regulator of inflammation. Recent studies showed that inflammation was largely suppressed by enhanced MCPIP1 expression in many inflammatory diseases. However, the role and potential mechanism of MCPIP1 in airway inflammation and mucus hypersecretion in asthma were still not well studied. This study was to explore the role of MCPIP1 in asthmatic airway inflammation and mucus hypersecretion in both mice and BEAS-2B cells, and its potential mechanism.

METHODS

In vivo, mice were sensitized and challenged by ovalbumin (OVA) to induce asthma. Airway inflammation and mucus secretion were analyzed. In vitro, BEAS-2B cells were chosen. Interleukin (IL)-13 was used to stimulate inflammation and mucus hypersecretion in cells. MCPIP1 Lentiviral vector (LA-MCPIP1) and plasmid-MCPIP1 were used to up-regulate MCPIP1 in lung and cells, respectively. MCP-1, thymic stromal lymphopoietin (TSLP), mucin 5AC (MUC5AC), MCPIP1, and GABAARβ2 expressions were measured in both lung and BEAS-2B cells. Immunofluorescence staining was performed to observe the expression of GABAARβ2 in cells.

RESULTS

MCPIP1 was up-regulated by LA-MCPIP1 (P < 0.001) and plasmid-MCPIP1 (P < 0.001) in lung and cells, respectively. OVA-induced airway inflammation and mucus hypersecretion, OVA-enhanced MCP-1, TSLP, MUC5AC, and GABAARβ2 expressions, and OVA-reduced MCPIP1 were significantly blunted by LA-MCPIP1 in mice (all P < 0.001). IL-13-enhanced MCP-1, TSLP, MUC5AC, and GABAARβ2 expressions, and IL-13-reduced MCPIP1 were markedly abrogated by plasmid-MCPIP1 in BEAS-2B cells (all P < 0.001).

CONCLUSION

The results of this study suggested that OVA and IL-13-induced airway inflammation and mucus hypersecretion were negatively regulated by MCPIP1 in both lung and BEAS-2B cells, involving GABAAR signaling pathway.

Repurposing existing drugs for COVID-19: an endocrinology perspective

BACKGROUND

Coronavirus Disease 2019 (COVID-19) is a multi-systemic infection caused by the novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), that has become a pandemic. Although its prevailing symptoms include anosmia, ageusia, dry couch, fever, shortness of brief, arthralgia, myalgia, and fatigue, regional and methodological assessments vary, leading to heterogeneous clinical descriptions of COVID-19. Aging, uncontrolled diabetes, hypertension, obesity, and exposure to androgens have been correlated with worse prognosis in COVID-19. Abnormalities in the renin-angiotensin-aldosterone system (RAAS), angiotensin-converting enzyme-2 (ACE2) and the androgen-driven transmembrane serine protease 2 (TMPRSS2) have been elicited as key modulators of SARS-CoV-2.

MAIN TEXT

While safe and effective therapies for COVID-19 lack, the current moment of pandemic urges for therapeutic options. Existing drugs should be preferred over novel ones for clinical testing due to four inherent characteristics: 1. Well-established long-term safety profile, known risks and contraindications; 2. More accurate predictions of clinical effects; 3. Familiarity of clinical management; and 4. Affordable costs for public health systems. In the context of the key modulators of SARS-CoV-2 infectivity, endocrine targets have become central as candidates for COVID-19. The only endocrine or endocrine-related drug class with already existing emerging evidence for COVID-19 is the glucocorticoids, particularly for the use of dexamethasone for severely affected patients. Other drugs that are more likely to present clinical effects despite the lack of specific evidence for COVID-19 include anti-androgens (spironolactone, eplerenone, finasteride and dutasteride), statins, N-acetyl cysteine (NAC), ACE inhibitors (ACEi), angiotensin receptor blockers (ARB), and direct TMPRSS-2 inhibitors (nafamostat and camostat). Several other candidates show less consistent plausibility. In common, except for dexamethasone, all candidates have no evidence for COVID-19, and clinical trials are needed.

CONCLUSION

While dexamethasone may reduce mortality in severely ill patients with COVID-19, in the absence of evidence of any specific drug for mild-to-moderate COVID-19, researchers should consider testing existing drugs due to their favorable safety, familiarity, and cost profile. However, except for dexamethasone in severe COVID-19, drug treatments for COVID-19 patients must be restricted to clinical research studies until efficacy has been extensively proven, with favorable outcomes in terms of reduction in hospitalization, mechanical ventilation, and death.

The Effect of Modified Porcine Surfactant Alone or in Combination with Polymyxin B on Lung Homeostasis in LPS-Challenged and Mechanically Ventilated Adult Rats

The study aimed to prove the hypothesis that exogenous surfactant and an antibiotic polymyxin B (PxB) can more effectively reduce lipopolysaccharide (LPS)-induced acute lung injury (ALI) than surfactant treatment alone, and to evaluate the effect of this treatment on the gene expression of surfactant proteins (SPs). Anesthetized rats were intratracheally instilled with different doses of LPS to induce ALI. Animals with LPS 500 μg/kg have been treated with exogenous surfactant (poractant alfa, Curosurf^®, 50 mg PL/kg b.w.) or surfactant with PxB 1% w.w. (PSUR + PxB) and mechanically ventilated for 5 hrs. LPS at 500 μg/kg increased lung edema, oxidative stress, and the levels of proinflammatory mediators in lung tissue and bronchoalveolar lavage fluid (BALF). PSUR reduced lung edema and oxidative stress in the lungs and IL-6 in BALF. This effect was further potentiated by PxB added to PSUR. Exogenous surfactant enhanced the gene expression of SP-A, SP-B, and SP-C, however, gene expression for all SPs was reduced after treatment with PSUR + PxB. In mechanically ventilated rats with LPS-induced ALI, the positive effect of exogenous surfactant on inflammation and oxidative stress was potentiated with PxB. Due to the tendency for reduced SPs gene expression after surfactant/PxB treatment topical use of PxB should be considered with caution.

Glucagon-like peptide-1 receptor mediates the beneficial effect of liraglutide in an acute lung injury mouse model involving the thioredoxin-interacting protein

Repurposing clinically used drugs is among the important strategies in drug discovery. Glucagon-like peptide-1 (GLP-1) and its diabetes-based drugs, such as liraglutide, possess a spectrum of extra-pancreatic functions, while GLP-1 receptor (GLP-1R) is most abundantly expressed in the lung. Recent studies have suggested that GLP-1-based drugs exert beneficial effects in chronic, as well as acute, lung injury rodent models. Here, we show that liraglutide pretreatment reduced LPS induced acute lung injury in mice. It significantly reduced lung injury score, wet/dry lung weight ratio, bronchoalveolar lavage fluid immune cell count and protein concentration, and cell apoptosis in the lung, and it was associated with reduced lung inflammatory cytokine and chemokine gene expression. Importantly, these effects were virtually absent in GLP-1R^-/- mice. A well-known function of GLP-1 and GLP-based drugs in pancreatic β-cells is the attenuation of high-glucose stimulated expression of thioredoxin-interacting protein (TxNIP), a key component of inflammasome. LPS-challenged lungs showed elevated TxNIP mRNA and protein expression, which was attenuated by liraglutide treatment in a GLP-1R-dependent manner. Hence, our observations suggest that GLP-1R is essential in mediating beneficial effects of liraglutide in acute lung injury, with the inflammasome component TxNIP as a potential target.

Interactions between antihyperglycemic drugs and the renin-angiotensin system: Putative roles in COVID-19. A mini-review

BACKGROUND

Diabetes mellitus is associated with a more severe course of coronavirus disease 2019 (COVID-19). The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizes angiotensin-converting enzyme II (ACE2) receptor for host cell entry. We aimed to assess the interactions between antihyperglycemic drugs and the renin-angiotensin system (RAS) and their putative roles in COVID-19.

METHODS

A literature search was performed using Pubmed to review the interrelationships between hyperglycemia, RAS and COVID-19, and the effects of antihyperglycemic medications.

RESULTS

The RAS has an essential role in glucose homeostasis and may have a role in COVID-19-induced lung injury. Some antihyperglycemic medications modulate RAS and might hypothetically alleviate the deleterious effect of angiotensin II on lung injury. Furthermore, most antihyperglycemic medications showed anti-inflammatory effects in animal models of lung injury.

CONCLUSIONS

Some antihyperglycemic medications might have protective effects against COVID-19-induced lung injury. Early insulin therapy seems very promising in alleviating lung injury.

Fucoidan inhibits LPS-induced acute lung injury in mice through regulating GSK-3β-Nrf2 signaling pathway

The purpose of this study was to investigate the protective effects of fucoidan on Lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. The mice were divided into the control, LPS, and LPS + fucoidan (20, 40, or 80 mg/kg) groups. LPS was given by intracheal instillation and fucoidan was given 1 h before LPS treatment. Myeloperoxidase (MPO) activity, malondialdehyde (MDA), superoxide dismutase (SOD), reactive oxygen species (ROS), glutathione (GSH) contents, and inflammatory cytokine production were detected. The results showed that LPS-induced TNF-α, IL-1β, and IL-6 production, lung wet/dry (W/D) ratio, ROS, MDA content, and MPO activity were suppressed by fucoidan. The levels of SOD and GSH were increased by fucoidan. Meanwhile, LPS-induced nuclear factor kappa-B (NF-κB) activation was dose-dependently attenuated by fucoidan. Furthermore, fucoidan increased the expression of nuclear factor erythroid-2 related factor 2 (Nrf2), Glycogen synthase kinase3β (GSK-3β), and heme oxygenase (HO-1). In vitro, the results demonstrated that fucoidan or GSK-3β inhibitor significantly inhibited LPS-induced TNF-α production in A549 cells. And the inhibition of fucoidan on TNF-α production was blocked by Nrf2 siRNA. This study showed fucoidan protected mice against LPS-induced ALI through inhibiting inflammatory and oxidative responses via regulating GSK-3β-Nrf2 signaling pathway.

Mesenchymal stem cells combined with liraglutide relieve acute lung injury through apoptotic signaling restrained by PKA/β-catenin

Background

ARDS and ALI are life-threatening diseases with extremely high mortality in patients. Different sources of MSCs could mitigate the symptoms of ALI from diverse mechanisms. Liraglutide is an activator of glucagon-like peptide-1 receptor (GLP-1R) that activates anti-apoptotic pathways and exerts anti-inflammatory effects. We mainly compared the effects of human chorionic villus-derived mesenchymal stem cells (hCMSCs), human bone marrow-derived mesenchymal stem cells (hBMSCs), and human adipose-derived mesenchymal stem cells (hAMSCs) on the treatment of ALI and explored the apoptosis mechanism of combination MSCs of liraglutide.

Methods

The proliferation of MSCs was detected by MTT assay. Western blot and RT-qPCR were used to detect the expression of GLP-1R, SPC, Ang-1, and KGF in MSCs stimulated by LPS and liraglutide. By using flow cytometry and TUNEL assay to compare the apoptosis of three MSCs under the action of LPS and liraglutide, we selected hCMSCs as the target cells to study the expression of apoptotic protein through the PKA/β-catenin pathway. In ALI animal models, we observed the effects of liraglutide alone, MSCs alone, and MSCs combined with liraglutide by H&E staining, cell counting, immunohistochemistry, and ELISA assay.

Results

We demonstrated that LPS attenuates the proliferation of the three MSCs and the expression of GLP-1R. Liraglutide could reverse the effects of LPS; increase the expression of SPC, Ang-1, and KGF; and can reduce the apoptosis of three MSCs through the PKA/β-catenin pathway. In the LPS-induced ALI model, MSCs combined with liraglutide showed a significant therapeutic effect, and hCMSCs combined with liraglutide have advantages in the treatment of ALI.

Conclusions

The therapeutic effect of combination MSCs of liraglutide on ALI was higher than that of MSCs alone or liraglutide alone, and liraglutide could alleviate the symptoms of ALI by reducing MSCs apoptosis.

Aloin suppresses lipopolysaccharide-induced acute lung injury by inhibiting NLRP3/NF-κB via activation of SIRT1 in mice

OBJECTIVE

The purpose of this study was to explore the protective effects and potential mechanisms of aloin on lipopolysaccharide (LPS)-induced acute lung injury (ALI).

METHODS

Mice were pretreatment with aloin 1 h before LPS administration. The number of inflammatory cells and the levels of TNF-α and IL-1β was detected. The lung histopathological changes, wet/dry ratio, MPO activity, GSH, MDA, SOD, and the expression of NF-κB and NLRP3 inflammasome were measured.

RESULTS

The results showed that aloin significantly inhibited the number of total cells, neutrophils, and macrophages, as well as the levels of TNF-α and IL-1β in BALF induced by LPS. In addition, pretreatment with aloin also inhibited LPS-induced lung histopathological injuries, lung wet/dry ratio, MPO activity, and MDA content. The levels of GSH and SOD were decreased by LPS and treatment of aloin could increase the levels of GSH and SOD. To study the protective mechanisms of alion on LPS-induced ALI, the expression of SIRT1, NF-κB and NLRP3 inflammasome were tested. We found that aloin significantly inhibited the activation of NF-κB and NLRP3 inflammasome in ALI induced by LPS. Meanwhile, aloin was found to increase the expression of SIRT1 and inhibition of SIRT1 by EX-527 reversed the protective effects of aloin.

CONCLUSIONS

These results suggest that aloin exerts its protective effects on LPS-induced ALI by activation SIRT1, which subsequently results in the suppression of NF-κB and NLRP3 inflammasome.

Intratracheal GLP-1 receptor agonist treatment up-regulates mucin via p38 and exacerbates emphysematous phenotype in mucus hypersecretory obstructive lung diseases

Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone that stimulates glucose-mediated insulin production by pancreatic beta cells. It is also associated with protective effects in multiple tissues. GLP-1 receptor is highly expressed in pulmonary tissue, hinting possible pulmonary delivery of GLP-1 drugs. However, little is known about the role of GLP-1 signaling in the lung, especially in mucus hypersecretory obstructive lung diseases. Here, we showed that treatment with exendin-4, a clinically available GLP-1 receptor agonist, up-regulates mucin expression in normal airway epithelial cells and in the lung of normal mice, indicating mucus stimulatory effect of GLP-1 under physiological condition. Exendin-4 also increased mucin expression in in vitro cellular and in vivo murine models of obstructive lung diseases via the activation of p38 MAP kinase. Notably, mucin induction in vivo exacerbated key pulmonary abnormalities including emphysematous phenotypes, implying that GLP-1 signaling in the lung is detrimental under pulmonary obstructive condition. Another GLP-1 receptor agonist liraglutide had similar induction of mucin. Together, our studies not only demonstrate novel physiological and pathological roles of GLP-1 in the lung but may also caution against the clinical use of inhaled GLP-1 receptor agonists in the patients with obstructive lung diseases.

Effect of hCMSCs and liraglutide combination in ALI through cAMP/PKAc/β-catenin signaling pathway

BACKGROUND

ALI/ARDS is the major cause of acute respiratory failure in critically ill patients. As human chorionic villi-derived MSCs (hCMSCs) could attenuate ALI in the airway injury model, and liraglutide, glucagon-like peptide 1 (GLP-1) agonist, possesses anti-inflammatory and proliferation promotion functions, we proposed to probe the potential combinatory effect of hCMSCs and liraglutide on ALI.

METHODS

We examined the time- and dose-dependent manner of GLP-1R, SPC, Ang-1, and FGF-10 with LPS via western blot and qRT-PCR. Western blot and chromatin immunoprecipitation assay detected the effects of liraglutide on GLP-1R, SPC, Ang-1, and FGF-10 through PKAc/β-catenin pathway and cAMP pathway. In the ALI animal model, we detected the effects of MSC and liraglutide combination on ALI symptoms by H&E staining, western blot, ELISA assays, calculating wet-to-dry ratio of the lung tissue, and counting neutrophils, leukocytes, and macrophages in mouse bronchoalveolar lavage fluid (BALF).

RESULTS

The data demonstrated that LPS reduced hCMSC proliferation and GLP-1R, SPC, Ang-1, and FGF-10 levels in a dose- and time-dependent manner. Liraglutide significantly dampened the reduction of GLP-1R, SPC, Ang-1, and FGF-10 and reversed the effect of LPS on hCMSCs, which could be regulated by GLP-1R and its downstream cAMP/PKAc/β-catenin-TCF4 signaling. Combination of hCMSCs with liraglutide showed more therapeutic efficacy than liraglutide alone in reducing LPS-induced ALI in the animal model.

CONCLUSIONS

These results reveal that the combination of hCMSCs and liraglutide might be an effective strategy for ALI treatment.

Glucagon-Like Peptide 1 and Atrial Natriuretic Peptide in a Female Mouse Model of Obstructive Pulmonary Disease

Glucagon-like peptide-1 (GLP-1) is protective in lung disease models but the underlying mechanisms remain elusive. Because the hormone atrial natriuretic peptide (ANP) also has beneficial effects in lung disease, we hypothesized that GLP-1 effects may be mediated by ANP expression. To study this putative link, we used a mouse model of chronic obstructive pulmonary disease (COPD) and assessed lung function by unrestrained whole-body plethysmography. In 1 study, we investigated the role of endogenous GLP-1 by genetic GLP-1 receptor (GLP-1R) knockout (KO) and pharmaceutical blockade of the GLP-1R with the antagonist exendin-9 to -39 (EX-9). In another study the effects of exogenous GLP-1 were assessed. Lastly, we investigated the bronchodilatory properties of ANP and a GLP-1R agonist on isolated bronchial sections from healthy and COPD mice.

Lung function did not differ between mice receiving phosphate-buffered saline (PBS) and EX-9 or between GLP-1R KO mice and their wild-type littermates. The COPD mice receiving GLP-1R agonist improved pulmonary function (P < .01) with less inflammation, but no less emphysema compared to PBS-treated mice. Compared with the PBS-treated mice, treatment with GLP-1 agonist increased ANP (nppa) gene expression by 10-fold (P < .01) and decreased endothelin-1 (P < .01), a peptide associated with bronchoconstriction. ANP had moderate bronchodilatory effects in isolated bronchial sections and GLP-1R agonist also showed bronchodilatory properties but less than ANP. Responses to both peptides were significantly increased in COPD mice (P < .05, P < .01).

Taken together, our study suggests a link between GLP-1 and ANP in COPD.

Curcumin Attenuates Asthmatic Airway Inflammation and Mucus Hypersecretion Involving a PPARγ-Dependent NF-κB Signaling Pathway In Vivo and In Vitro

Asthma is characterized by airway inflammation and mucus hypersecretion. Curcumin possessed a potent anti-inflammatory property involved in the PPARγ-dependent NF-κB signaling pathway. Then, the aim of the current study was to explore the value of curcumin in asthmatic airway inflammation and mucus secretion and its underlying mechanism. In vivo, mice were sensitized and challenged by ovalbumin (OVA) to induce chronic asthma. Airway inflammation and mucus secretion were analyzed. In vitro, BEAS-2B cells were obtained. MCP-1, MUC5AC, and PPARγ expression and the phosphorylation of NF-κB p65 and NF-κB p65 DNA-binding activity were measured in both the lungs and BEAS-2B cells. shRNA-PPARγ was used to knock down PPARγ expression. We found that OVA-induced airway inflammation and mucus hypersecretion in mice, OVA and IL-4-induced upregulation of MCP-1 and MUC5AC, suppression of PPARγ, and activation and translocation of NF-κB p65 were notably improved by curcumin both in vivo and in vitro. Our data also showed that these effects of curcumin were significantly abrogated by shRNA-PPARγ. Taken together, our results indicate that curcumin attenuated OVA-induced airway inflammation and mucus hypersecretion in mice and suppressed OVA- and IL-4-induced upregulation of MCP-1 and MUC5AC both in vivo and in vitro, most likely through a PPARγ-dependent NF-κB signaling pathway.

[Curcumin suppresses cigarette smoke extract-induced oxidative stress through PPARγ/ NF-κB pathway in human bronchial epithelial cells in vitro]

OBJECTIVE

To investigate the effect of curcumin against cigarette smoke extract (CSE)- induced oxidative stress in human bronchial epithelial cells and explore the underlying mechanism.

METHODS

Human bronchial epithelial cell line 16HBE was treated for 24 h with curcumin, CSE, CSE + curcumin, and CSE + curcumin with transfection by a short hairpin RNA targeting PPARγ (shPPARγ). MTT assay was used to observe the changes in the cell viability after the treatments. Quantitative real-time PCR was performed to detect the mRNA expressions of tumor necrosis factor-α (TNF-α), iNOS and PPARγ in the cells, and the protein expressions of iNOS, PPARγ and the phosphorylation of NF-κB p65 were detected using Western blotting.

RESULTS

The treatments did not cause significant changes in the cell viability. Exposure to CSE for 24 h significantly lowered PPARγ expression and increased TNF-α and iNOS expressions and phosphorylation of NF-κB p65 in the cells. The effects of CSE were significantly suppressed by curcumin, but transfection of the cells with shRNA-PPARγ obviously abrogated the suppressive effects of curcumin.

CONCLUSIONS

Curcumin suppresses CSE-induced oxidative stress and inflammation via the PPARγ/NF-κB signaling pathway in 16HBE cells, suggesting the potential of curcumin in the treatment of chronic obstructive pulmonary disease.