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

LIRAGLUTIDE ALLEVIATES ACUTE LUNG INJURY AND MORTALITY IN PNEUMONIA-INDUCED SEPSIS THROUGH REGULATING SURFACTANT PROTEIN EXPRESSION AND SECRETION

ABSTRACT

Glucagon-like peptide 1 (GLP-1) analogs are used to treat type 2 diabetes, and they can regulate insulin secretion, energy homeostasis, inflammation, and immune cell function. This study sought to determine whether the GLP-1 analog liraglutide exerts a beneficial action in an acute lung injury model of pneumonia-induced sepsis. Methods: Wild-type FVB/NJ mice (n = 114) were infected by intratracheal injection with Pseudomonas aeruginosa Xen5 (4 × 10 4 CFU/mouse) or an equal volume (50 μL) of saline (control) with or without a subcutaneous injection of liraglutide (2 mg/kg, 30 min after infection). Mice were killed 24 h after infection. Lung tissues and BALF were analyzed. In separate experiments, the dynamic growth of bacteria and animal mortality was monitored using in vivo imaging system within 48 h after infection. In addition, primary lung alveolar type II cells isolated from mice were used to study the mechanism of liraglutide action. Result: Liraglutide improved survival ( P < 0.05), decreased bacterial loads in vivo , and reduced lung injury scores ( P < 0.01) in septic mice. Liraglutide-treated mice showed decreased levels of inflammatory cells ( P < 0.01) and proinflammatory cytokines (TNF-α and IL-6) ( P < 0.01) in the lung compared with septic controls. Liraglutide significantly increased pulmonary surfactant proteins (SP-A and SP-B) expression/secretion ( P < 0.01) and phospholipid secretion ( P < 0.01) in vivo . Primary alveolar type II cells pretreated with liraglutide improved SP-A and SP-B expression after LPS exposure ( P < 0.01). Conclusion: Liraglutide attenuates mortality and lung inflammation/injury in pneumonia-induced sepsis. The increased surfactant expression/secretion and anti-inflammatory effects of liraglutide represent potential mechanisms by GLP-1 agonists potentiate host defense and maintain alveolar respiratory function in acute lung injury.

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.

Dulaglutide provides protection against sepsis-induced lung injury in mice by inhibiting inflammation and apoptosis

Sepsis is a dangerous condition with a high mortality rate. In addition to promoting insulin secretion in a glucose-dependent manner, glucagon-like peptide-1 (GLP-1) also exhibits anti-inflammatory properties. Dulaglutide is a glucagon-like peptide-1 receptor agonist (GLP-1 RA). In this study, we investigated the effects and mechanism of action of dulaglutide (Dul) in lipopolysaccharide (LPS) induced lung injury in mice with sepsis. In mice with LPS (15 mg/kg, ip, qd)-induced acute lung injury, the administration of dulaglutide (0.6 mg/kg, ip, qd) improved weight loss, reduced lung injury, reversed the increase in IL-1β, TNF-α, IL-6, CXCL1, CCL2 and CXCL2 expression in the lung, and reduced the infiltration of neutrophils and macrophages in the lung tissues. The decline in caspase-3, cleaved caspase-3, caspase-8, and Bcl-2/Bax expression and the increase in the number of TUNEL positive cells in the lung were reversed, suggesting that GLP-1RA could play a protective role in the lung by inhibiting inflammation and apoptosis. In addition, GLP-1RA could reduce the expression of P-STAT3 and NLRP3, suggesting that P-STAT3 and NLRP3 may be potential targets against lung injury in sepsis. Collectively, our data demonstrated that GLP-1RA exerts a protective effect against sepsis-induced lung injury through mechanisms related to the inhibition of inflammation, apoptosis, and STAT3 signaling.

Short-term semaglutide treatment improves FGF21 responsiveness in primary hepatocytes isolated from high fat diet challenged mice

Metabolic functions of GLP-1 and its analogues have been extensively investigated. In addition to acting as an incretin and reducing body weight, we and others have suggested the existence of GLP-1/fibroblast growth factor 21 (FGF21) axis in which liver mediates certain functions of GLP-1 receptor agonists. In a more recent study, we found with surprise that four-week treatment with liraglutide but not semaglutide stimulated hepatic FGF21 expression in HFD-challenged mice. We wondered whether semaglutide can also improve FGF21 sensitivity or responsiveness and hence triggers the feedback loop in attenuating its stimulation on hepatic FGF21 expression after a long-term treatment. Here, we assessed effect of daily semaglutide treatment in HFD-fed mice for 7 days. HFD challenge attenuated effect of FGF21 treatment on its downstream events in mouse primary hepatocytes, which can be restored by 7-day semaglutide treatment. In mouse liver, 7-day semaglutide treatment stimulated FGF21 as well as genes that encode its receptor (FGFR1) and the obligatory co-receptor (KLB), and a battery of genes that are involved in lipid homeostasis. In epididymal fat tissue, expressions of a battery genes including Klb affected by HFD challenge were reversed by 7-day semaglutide treatment. We suggest that semaglutide treatment improves FGF21 sensitivity which is attenuated by HFD challenge.

Liraglutide ameliorates gentamicin-induced acute kidney injury in rats via PGC-1α- mediated mitochondrial biogenesis: Involvement of PKA/CREB and Notch/Hes-1 signaling pathways

Acute kidney injury (AKI) is a challenging side effect which may clinically impede the use of gentamicin (GM). The present study explored the impact of liraglutide (Lir) on GM-induced kidney injury in rats. Lir (0.2 and 0.4 mg/kg, s.c) was given for 10 days (a dose/day) starting 3 days before giving GM (100 mg/kg, i.p) once daily for 7 days. Interestingly, Lir notably ameliorated GM-induced elevated levels of renal injury markers; urea and creatinine. Moreover, Lir remarkably mitigated malondialdehyde (MDA) level and elevated glutathione (GSH) level as well as superoxide dismutase (SOD) activity. Also, Lir pre-treatment notably diminished inflammatory markers levels; interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), vascular cell adhesion molecule (VCAM), monocyte chemoattractant protein 1 (MCP-1) and interferon gamma (INF-γ). In addition, Lir significantly replenished expression of Peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1α), Protein kinase A (PKA), cAMP response element-binding protein (CREB), nuclear Nuclear factor erythroid 2-related factor 2 (Nrf2), heme Oxygenase-1 (HO-1), B-cell lymphoma 2 (Bcl-2), and remarkably attenuated expression of Notch homolog 1 (Notch1), Hairy and enhancer of split-1 (Hes-1), Bcl-2-associated X (Bax), cleaved caspase 3 and nuclear Nuclear factor Kappa B (NF-κB (p65)). The nephroprotective activity of Lir was further confirmed by histopathological examination as well as transmission electron microscopy (TEM). In conclusion Lir achieved its nephroprotective effects through the amelioration of oxidative stress, inflammatory and apoptotic manifestations. It is worth-mentioning that the current study is the first to focus on the involvement of mitochondrial biogenesis and its upstream regulators, PKA/CREB and Notch/Hes-1 signaling pathways in the nephroprotective potentials of Lir. The attenuation of the aforementioned injurious aspects is partially attributed to the improvement of the mitochondrial status as demonstrated by elevated PGC-1α expression via acceleration of PKA/CREB and abatement of Notch/Hes-1 signaling pathways.

An update on the role of thioredoxin-interacting protein in diabetic kidney disease: A mini review

Thioredoxin-interacting protein (TXNIP) was first isolated from Vitamin D3-exposed HL60 cells. TXNIP is the main redox-regulating factor in various organs and tissues. We begin with an overview of the TXNIP gene and protein information, followed by a summary of studies that have shown its expression in human kidneys. Then, we highlight our current understanding of the effect of TXNIP on diabetic kidney disease (DKD) to improve our understanding of the biological roles and signal transduction of TXNIP in DKD. Based on the recent review, the modulation of TXNIP may be considered as a new target in the management of DKD.

Application of glucagon-like peptide-1 receptor antagonists in fibrotic diseases

Fibrosis can occur in various organs, leading to structural destruction, dysfunction, and even organ failure. Hence, organ fibrosis is being actively researched worldwide. Glucagon-like peptide-1 (GLP-1), a naturally occurring hormone, binds to a G-protein-coupled receptor widely distributed in the pancreas, kidney, lung, heart, gastrointestinal tract, and other organs. Synthetic GLP-1 analogs can be used as GLP-1 receptor agonists (GLP-1RAs) for treating diabetes mellitus. In recent years, GLP-1RAs have also been found to exert anti-inflammatory, antioxidant, and cardiovascular protective effects. GLP-1RAs have also been shown to inhibit fibrosis of solid organs, such as the lung, heart, liver, and kidney. In this review, we discuss the advancements in research on the role of GLP-1RAs in the fibrosis of the heart, lung, liver, kidney, and other organs to obtain new clues for treating organ fibrosis.

Obesity and COVID-19: Mechanistic Insights From Adipose Tissue

Obesity is associated with an increase in morbidity and mortality from coronavirus disease 2019 (COVID-19). The risk is related to the cytokine storm, a major contributor to multiorgan failure and a pathological character of COVID-19 patients with obesity. While the exact cause of the cytokine storm remains elusive, disorders in energy metabolism has provided insights into the mechanism. Emerging data suggest that adipose tissue in obesity contributes to the disorders in several ways. First, adipose tissue restricts the pulmonary function by generation of mechanical pressures to promote systemic hypoxia. Second, adipose tissue supplies a base for severe acute respiratory syndrome coronavirus 2 entry by overexpression of viral receptors [angiotensin-converting enzyme 2 and dipeptidyl peptidase 4]. Third, impaired antiviral responses of adipocytes and immune cells result in dysfunction of immunologic surveillance as well as the viral clearance systems. Fourth, chronic inflammation in obesity contributes to the cytokine storm by secreting more proinflammatory cytokines. Fifth, abnormal levels of adipokines increase the risk of a hyperimmune response to the virus in the lungs and other organs to enhance the cytokine storm. Mitochondrial dysfunction in adipocytes, immune cells, and other cell types (endothelial cells and platelets, etc) is a common cellular mechanism for the development of cytokine storm, which leads to the progression of mild COVID-19 to severe cases with multiorgan failure and high mortality. Correction of energy surplus through various approaches is recommended in the prevention and treatment of COVID-19 in the obese patients.

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.

Antidiabetic effects of quercetin and liraglutide combination through modulation of TXNIP/IRS-1/PI3K pathway

The study was designed to assess the possible augmented antidiabetic effects of combining quercetin and liraglutide in a type 1 diabetes model, with emphasis on the contribution of hepatic thioredoxin interacting protein (TXNIP)/insulin receptor substrate 1 (IRS-1)/phosphatidyl inositol-3 kinase (PI3K) pathway. The wound-healing effects were also examined. Diabetes was induced by a single i.p STZ injection (55 mg/kg). Diabetic rats were treated with either quercetin (100 mg/kg/day, orally) or liraglutide (0.3 mg/kg/twice daily, S.C.) or their combination. Drugs were also applied topically on the wound. Blood glucose levels, serum albumin, total protein, total cholesterol and triglycerides were measured. Histopathological examination of the liver, pancreas and skin tissues was performed using haematoxylin and eosin staining. The hepatic malondialdehyde level was measured spectrophotometrically. Hepatic TXNIP and PI3K levels were measured by enzyme-linked immunsorbent assay (ELISA). Tissue expression of IRS-1 and phospho-IRS-1 (Ser 616) was assessed by immunohistochemistry. Quercetin, liraglutide and their combination effectively decreased blood glucose levels, improved lipid profile, upregulated albumin and total protein serum levels and reduced hepatic oxidative stress with the combination being most effective. Moreover, the combination group showed enhanced wound-healing effects and almost normalized hepatic and pancreatic histopathology. Quercetin and/or liraglutide significantly decreased TXNIP levels and serine phosphorylation of IRS-1 and increased PI3K levels compared to the diabetic untreated group. Interestingly, only the combination therapy normalized hepatic IRS-1 expression. The combination of quercetin and liraglutide showed enhanced antidiabetic effects, possibly through lowering hepatic TXNIP levels, with the resultant up-regulation of the IRS-1/PI3K pathway.

Narrative review on clinical considerations for patients with diabetes and COVID-19: More questions than answers

BACKGROUND-AIM

Diabetes, obesity and hypertension are common comorbidities associated with increased severity and mortality rates from Corona Virus Disease (COVID)-19.

METHODS

In this narrative review (using the PubMed database), we discuss epidemiological data and pathophysiological links between diabetes and COVID-19. The potential effects of glycaemic control and antidiabetic drugs on the prevalence and outcomes of COVID-19 are also reviewed, as well as the role of telemedicine and diabetes self-management in the post-COVID-19 era.

RESULTS

Diabetes has been linked to COVID-19 morbidity and mortality, although further research is needed to elucidate this association. In the meantime, physicians should be aware of the potential rise in the prevalence of diabetes (due to unhealthy lifestyle changes during the pandemic), its severity and complications and focus on achieving optimal diabetes prevention and management. Telemedicine and diabetes self-management may help towards this direction. Dipeptidyl-peptidase 4 (DPP4) inhibitors, glucagon-like peptide-1 (GLP-1) receptor agonists and sodium-glucose transporter 2 (SGLT2) inhibitors may affect viral entry and infection, and thus COVID-19 outcomes, as shown in observational studies.

CONCLUSION

Diabetes has been associated with COVID-19 development and progression. Certain antidiabetic drugs may influence COVID-19 prevention and management. The results of ongoing randomized clinical trials will shed more light on this field.

Titanium Dioxide Nanoparticles Exacerbate Allergic Airway Inflammation via TXNIP Upregulation in a Mouse Model of Asthma

Titanium dioxide nanoparticles (TiO₂NPs) are widely used in industrial and medicinal fields and in various consumer products, and their increasing use has led to an increase in the number of toxicity studies; however, studies investigating the underlying toxicity mechanism have been rare. In this study, we evaluated potential toxic effects of TiO₂NPs exposure on lungs as well as the development of asthma through the ovalbumin (OVA)-induced mouse model of asthma. Furthermore, we also investigated the associated toxic mechanism. TiO₂NPs caused pulmonary toxicity by exacerbating the inflammatory response, indicated by an increase in the number and level of inflammatory cells and mediators, respectively. OVA-induced asthma exposed mice to TiO₂NPs led to significant increases in inflammatory mediators, cytokines, and airway hyperresponsiveness compared with those in non-exposed asthmatic mice. This was also accompanied by increased inflammatory cell infiltration and mucus production in the lung tissues. Additionally, TiO₂NPs decreased the expression of B-cell lymphoma 2 (Bcl2) and the expressions of thioredoxin-interacting protein (TXNIP), phospho-apoptosis signal-regulating kinase 1, Bcl2-associated X, and cleaved-caspase 3 were escalated in the lungs of asthmatic mice compared with those in non-exposed asthmatic mice. These responses were consistent with in vitro results obtained using human airway epithelial cells. TiO₂NPs treated cells exhibited an increase in the mRNA and protein expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α with an elevation of TXNIP signaling compared to non-treated cells. Moreover, pathophysiological changes induced by TiO₂NP treatment were significantly decreased by TXNIP knockdown in airway epithelial cells. Overall, TiO₂NP exposure induced toxicological changes in the respiratory tract and exacerbated the development of asthma via activation of the TXNIP-apoptosis pathway. These results provide insights into the underlying mechanism of TiO₂NP-mediated respiratory toxicity.

Use of GLP1RAs and occurrence of respiratory disorders: A meta-analysis of large randomized trials of GLP1RAs

OBJECTIVES

No large sample studies have been designed to evaluate the efficacy of glucagon-like peptide-1 receptor agonists (GLP1RAs) in the primary and secondary prevention of respiratory disorders. We aimed at evaluating the relationship between use of GLP1RAs and occurrence of 12 kinds of respiratory disorders.

METHODS

Large randomized placebo-controlled trials of GLP1RAs were included. We conducted meta-analysis using random effects model and measured heterogeneity using I² . Treatment effect was presented as risk ratio (RR) and 95% confidence interval (CI).

RESULTS

Seven trials including 55 922 participants were included in meta-analysis. The occurrence rates of various respiratory disorders were low, with the minimum of 0.02% (pulmonary fibrosis) and the maximum of 2.31% (pneumonia). Although not reaching statistical significance, GLP1RAs versus placebo showed the reduced trends in the risks of nine kinds of respiratory disorders including pneumonia (RR 0.89, 95% CI 0.78-1.01), squamous cell carcinoma of lung (SCCL; RR 0.55, 95% CI 0.25-1.21), asthma (RR 0.82, 95% CI 0.51-1.32), and chronic obstructive pulmonary disease (COPD; RR 0.89, 95% CI 0.73-1.10), but the increased trend in interstitial lung disease (ILD; RR 1.89, 95% CI 0.87-4.08). GLP1RAs had neutral effects on two other respiratory disorders. Heterogeneity in any meta-analysis was absent or low.

CONCLUSION

GLP1RAs show the reduced trends in the risks of nine kinds of respiratory disorders (eg, pneumonia, SCCL, asthma, and COPD), but the increased trend in the risk of ILD. However, these findings need to be validated by further studies due to the low incidence rates of all the respiratory disorders.

Friend or foe? ACE2 inhibitors and GLP-1R agonists in COVID-19 treatment

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a pandemic since WHO made the statement on March 11, 2020. The infection is causing a high mortality in old people, especially those with obesity, type 2 diabetes (T2D) or cardiovascular diseases (CVD). Extra cautions are needed in the treatment of those patients. The CVD drugs ACEIs and ARBs, as well as the T2D drugs GLP-1R agonists, were shown to activate angiotensin-converting enzyme 2 (ACE2) expression in experimental animals. Elevated ACE2 expression may accelerate virus entrance into the host cells during the infection for its replication. However, expression of the soluble ACE2, may neutralize the virus to limit the infection and replication. Given that obese, diabetes and CVD patients often take those medicines in the treatment and prevention of blood pressure and glucose elevation, it remains to be determined whether those medicines represent friend or foe in the treatment of COVID-19. We suggest that retrospective studies should be conducted to determine the exact impact of those medicines in obese, diabetic, or CVD patients who had COVID-19. Results obtained will provide guidance whether those drugs can be utilized in COVID-19 patients with obesity, diabetic, or CVD.

The active GLP-1 analogue liraglutide alleviates H9N2 influenza virus-induced acute lung injury in mice

Influenza virus is responsible for significant morbidity and mortality worldwide. Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is the major cause of death in influenza virus infected patients. Recent studies indicated that active glucagon like peptide-1 (GLP-1) encoded by glucagon (GCG) gene exerts anti-inflammatory functions. The aim of this study was to determine the potential role of active GLP-1 in H9N2 influenza virus-induced ALI/ARDS in mice. First, we uncovered that GCG mRNA expression levels and GCG precursor protein levels were significantly increased, but total GLP-1 and active GLP-1 levels were decreased in the lungs of H9N2-infected mice. Next, liraglutide, an active GLP-1 analogue, was used to treat infected mice and to observe its effects on H9N2 virus-induced ALI. Liraglutide treatment ameliorated the declined body weight, decreased food intake and mortality observed in infected mice. It also alleviated the severity of lung injury, including lowering lung index, decreasing inflammatory cell infiltration and lowing total protein levels in bronchoalveolar lavage fluid (BALF). In addition, liraglutide did not influence viral titers in infected lungs, but decreased the levels of interleukin-1β, interleukin-6 and tumor necrosis factor-α in BALF. These results indicated that liraglutide alleviated H9N2 virus-induced ALI in mice most likely due to lower levels of pro-inflammatory cytokines.