Ramelteon protects against human pulmonary microvascular endothelial cell injury induced by lipopolysaccharide (LPS) via activating nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway

Inhaled aerosolized algal polysaccharides: A novel and reliable strategy for treating pneumonia through inflammation and oxidative stress inhibition

Sepsis-associated acute lung injury (ALI) poses a significant threat, characterized by inflammation and oxidative damage. Effective drugs targeting these aspects with reliable drug delivery systems are vital for ALI management. This study aimed to evaluate the influence of algal polysaccharides (APs) with aerosolized drug delivery in ALI mice and clarify the underlying mechanism. To induce the sepsis-associated acute lung injury (ALI) model, mice were administered intraperitoneal injections of 10 mg/kg LPS for 48 h in vivo. ALI mice received APs via atomization to arrive at different sites within the lungs. Lung tissue samples and bronchoalveolar lavage fluid (BALF) were collected to access lung injury parameters. Concurrently, western blotting, H&E staining, and immunofluorescence (IF) were applied to investigate the specific impact of APs on ALI. The results showed that APs protect lung tissue against ALI by inhibiting inflammation and mitigating oxidative stress-induced damage. This study highlights promising avenues for ALI intervention using natural compounds with anti-inflammatory and antioxidant properties.

Ameliorative effects of topical ramelteon on imiquimod-induced psoriasiform inflammation in mice

Psoriasis is a long-lasting, immune-related inflammatory skin disease that affects 2-3% of the global population. It is distinguished by erythematous, silvery, and scaly patches. Ramelteon is a type of melatonin agonist that is used to treat insomnia. It has enhanced non-classical immunomodulatory and anti-inflammatory activities. The aim of the study is to assess the ameliorative effects of topical ramelteon on imiquimod (IMQ)-aggravated psoriasiform-like dermatosis in mice. The 32 albino mouse males were placed into six groups of eight animals, all of them. With the exception of the control group, all groups gained a once-a-day regimen of topical imiquimod 5% cream at a dose of 62.5 mg for eight uninterrupted days, while mice in the control group gained vaseline-based ointment alternately. Immediately after an 8-day induction period in the imiquimod group, mice in the clobetasol and ramelteon treatment groups obtained a twice-daily regimen of topical clobetasol propionate 0.05% ointment and 0.1% ointment, respectively, for a further 8 days. This extends the total duration of the experimental study to 16 continuous days. The findings of our study found that ramelteon significantly mitigated the concentrations of inflammatory cytokines in the skin tissue, including interleukin (IL)-6, IL-17A, IL-23, tumor necrosis factor-α (TNF-α), and vascular endothelial growth factor (VEGF), as well as the scores associated with psoriatic lesions, including erythema, scaling, skin thickening, ear thickness, and overall cumulative PASI scores. Additionally, the anti-inflammatory impact of ramelteon was achieved by markedly increasing IL-10 levels in the skin tissue and correcting cutaneous histopathological alterations. Ramelteon ointment (0.1%) was comparable to that of clobetasol (0.05%) ointment in alleviating a mouse model of imiquimod-induced psoriasiform inflammation; this is probably due to its potential anti-inflammatory and immunomodulatory activities. Therefore, ramelteon could be a good additive option for therapeutic management of immune-triggered inflammatory conditions such as psoriasis.

Preventive effects of Ramelteon on bleomycin-induced pulmonary fibrosis in mice

Pulmonary fibrosis (PF) is a devastating lung disease that leads to impaired lung function and ultimately death. Several studies have suggested that melatonin, a hormone involved in regulating sleep-wake cycles, may be effective in improving PF. Ramelteon, an FDA-approved melatonin receptor agonist, has shown promise in exerting an anti-PF effect similar to melatonin. However, further investigations are required for illuminating the extent on its therapeutic benefits and the underlying molecular mechanisms. In this work, a mouse lung fibrosis model was built through intratracheal administration of bleomycin (BLM). Subsequently, the mice were administrated Ramelteon for a duration of 3 weeks to explore its efficacy and mechanism of action. Additionally, we utilized a TGF-β1-induced MRC-5 cell model to further investigate the molecular mechanism underlying ramelteon's effects. Functionally, Ramelteon partially abrogated TGF-β1-induced pulmonary fibrosis and reduced fibroblast proliferation, extracellular matrix deposition, and differentiation into myofibroblasts. In vivo experiments, ramelteon attenuated BLM-induced pulmonary fibrosis and collagen deposition. Mechanistically, ramelteon exerts its beneficial effect by alleviating translocation and expression of YAP1, a core component of Hippo pathway, from cytoplasm to nucleus; however, overexpression of YAP1 reversed this effect. In conclusion, our findings indicate that ramelteon can improve PF by regulating Hippo pathway and may become a potential candidate as a therapy to PF.

Effect fraction of Bletilla striata (Thunb.) Reichb.f. alleviates LPS-induced acute lung injury by inhibiting p47phox/NOX2 and promoting the Nrf2/HO-1 signaling pathway

BACKGROUND & AIMS

The effect fraction of Bletilla striata (Thunb.) Reichb.f. (EFBS), a phenolic-rich extract, has significant protective effects on lipopolysaccharide (LPS)-induced acute lung injury (ALI), but its composition and molecular mechanisms are unclear. This study elucidated its chemical composition and possible protective mechanisms against LPS-induced ALI from an antioxidant perspective.

METHODS

EFBS was prepared by ethanol extraction, enriched by polyamide column chromatography, and characterized using ultra-performance liquid chromatography/time-of-flight mass spectrometry. The LPS-induced ALI model and the RAW264.7 model were used to evaluate the regulatory effects of EFBS on oxidative stress, and transcriptome analysis was performed to explore its possible molecular mechanism. Then, the pathway by which EFBS regulates oxidative stress was validated through inhibitor intervention, flow cytometry, quantitative PCR, western blotting, and immunofluorescence techniques.

RESULTS

A total of 22 compounds in EFBS were identified. The transcriptome analyses of RAW264.7 cells indicated that EFBS might reduce reactive oxygen species (ROS) production by inhibiting the p47phox/NADPH oxidase 2 (NOX2) pathway and upregulating the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. Both in vitro and in vivo data confirmed that EFBS significantly inhibited the expression and phosphorylation of p47phox protein, thereby weakening the p47phox/NOX2 pathway and reducing ROS production. EFBS significantly increased the expression of Nrf2 in primary peritoneal macrophages and lung tissue and promoted its nuclear translocation, dose-dependent increase in HO-1 levels, and enhancement of antioxidant activity. In vitro, both Nrf2 and HO-1 inhibitors significantly reduced the scavenging effects of EFBS on ROS, further confirming that EFBS exerts antioxidant effects at least partially by upregulating the Nrf2/HO-1 pathway.

CONCLUSIONS

EFBS contains abundant phenanthrenes and dibenzyl polyphenols, which can reduce ROS production by inhibiting the p47phox/NOX2 pathway and enhance ROS clearance activity by upregulating the Nrf2/HO-1 pathway, thereby exerting regulatory effects on oxidative stress and improving LPS-induced ALI.

Ramelteon attenuates renal ischemia and reperfusion injury through reducing mitochondrial fission and fusion and inflammation

Background

Renal ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury (AKI). This study explored the function and mechanisms of ramelteon on IRI-induced AKI.

Methods

Mice were randomly divided into five groups: Sham, IRI, IRI + ramelteon (0.3 mg/kg), IRI + ramelteon (1 mg/kg), and IRI + ramelteon (3 mg/kg). Mice were intraperitoneally treated with ramelteon for 7 days before IRI. IRI was accomplished by bilateral renal artery clamping for 30 minutes, after which the clamps were removed for blood reperfusion. HK-2 cells were randomly divided into five groups: control, hypoxia/reoxygenation (H/R), H/R + ramelteon (10 nM), H/R + ramelteon (30 nM), and H/R + ramelteon (60 nM). HK-2 cells were prophylactically treated with ramelteon and then exposed to H/R.

Results

Ramelteon attenuated renal injury, inhibited cell apoptosis, decreased reactive oxygen species (ROS) generation, and suppressed levels of interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β). Ramelteon decreased apoptosis-related protein Bax and TLR4-related proteins (TLR4, MyD88, p-IκBα, and p-p65 NF-κB), enhanced apoptosis-related protein Bcl-2. Furthermore, ramelteon increased mitochondrial membrane potential in H/R cells. Mitochondrial-related proteins (Drp1, Fis1, and Mff) were abated, whereas Mfn1 and Mfn2 were enhanced in H/R induced cells.

Conclusions

Ramelteon attenuates renal injury induced by IRI and H/R, which is involved in apoptosis, mitochondrial damage, and inflammation.

The melatonin agonist ramelteon attenuates bleomycin-induced lung fibrosis by suppressing the NLRP3/TGF-Β1/HMGB1 signaling pathway

PURPOSE

The possible effects of ramelteon, a melatonin receptor agonist on bleomycin-induced lung fibrosis were analyzed via transforming growth factor β1 (TGF-β1), the high mobility group box 1 (HMGB1) and Nod-like receptor pyrin domain-containing 3 (NLRP3) which are related to the fibrosis process.

MATERIALS AND METHODS

Bleomycin (0.1 ​mL of 5 ​mg/kg) was administered by intratracheal instillation to induce pulmonary fibrosis (PF). Starting 24 ​h after bleomycin administration, a single dose of ramelteon was administered by oral gavage to the healthy groups, i.e. PF ​+ ​RM2 (pulmonary fibrosis model with bleomycin ​+ ​ramelteon at 2 ​mg/kg) and PF ​+ ​RM4 (pulmonary fibrosis model with bleomycin ​+ ​ramelteon at 4 ​mg/kg) at 2 and 4 ​mg/kg doses, respectively. Real-time polymerase chain reaction (real-time PCR) analyses, histopathological, and immunohistochemical staining were performed on lung tissues. Lung tomography images of the rats were also examined.

RESULTS

The levels of TGF-β1, HMGB1, NLRP3, and interleukin 1 beta (IL-1β) mRNA expressions increased as a result of PF and subsequently decreased with both ramelteon doses (p ​< ​0.0001). Both doses of ramelteon partially ameliorated the reduction in the peribronchovascular thickening, ground-glass appearances, and reticulations, and the loss of lung volume.

CONCLUSIONS

The severity of fibrosis decreased with ramelteon application. These effects of ramelteon may be associated with NLRP3 inflammation cascade.

The role of melatonin in the development of postmenopausal osteoporosis

Melatonin is an important endogenous hormone that modulates homeostasis in the microenvironment. Recent studies have indicated that serum melatonin levels are closely associated with the occurrence and development of osteoporosis in postmenopausal women. Exogenous melatonin could also improve bone mass and increase skeletal strength. To determine the underlying mechanisms of melatonin in the prevention and treatment of postmenopausal osteoporosis, we performed this review to analyze the role of melatonin in bone metabolism according to its physiological functions. Serum melatonin is related to bone mass, the measurement of which is a potential method for the diagnosis of osteoporosis. Melatonin has a direct effect on bone remodeling by promoting osteogenesis and suppressing osteoclastogenesis. Melatonin also regulates the biological rhythm of bone tissue, which benefits its osteogenic effect. Additionally, melatonin participates in the modulation of the bone microenvironment. Melatonin attenuates the damage induced by oxidative stress and inflammation on osteoblasts and prevents osteolysis from reactive oxygen species and inflammatory factors. As an alternative drug for osteoporosis, melatonin can improve the gut ecology, remodel microbiota composition, regulate substance absorption and maintain metabolic balance, all of which are beneficial to the health of bone structure. In conclusion, our review systematically demonstrates the effects of melatonin on bone metabolism. Based on the evidence in this review, melatonin will play a more important role in the diagnosis, prevention and treatment of postmenopausal osteoporosis.

Ginkgolide A Participates in LPS-Induced PMVEC Injury by Regulating miR-224 and Inhibiting p21 in a Targeted Manner

Most studies have focused on the protective effects of ginkgolide A against ischemia/reperfusion-induced cardiomyopathy and injury of the brain, liver, and other organs, but there are few reports about the protection of lung tissues. This study was designed to clarify the protection of ginkgolide A against lipopolysaccharide (LPS)-induced pulmonary microvascular endothelial cell (PMVEC) injury. PMVECs were extracted and fell into control, LPS, and ginkgolide A groups. Next, we delved into the growth activity and apoptosis rate of cells via the CCK-8 assay and Hoechst staining, independently. Beyond that, western blotting (WB) was implemented for measurement of the expressions of cyclin D1, cyclin-dependent kinase 4 (CDK4), and CDK inhibitor (p21) that pertained to the cell cycle. The target sites of ginkgolide A were confirmed by miRNA array and real-time quantitative PCR. The relationship between miR-224 and p21 was analyzed using dual-luciferase reporter gene assay. Compared with the control group, the LPS group and ginkgolide A group had significantly decreased cell growth activity and relative expressions of cyclin D1 and CDK4 and elevated apoptosis rate and p21 expression. Pronounced elevations were observable in the cell growth activity and expressions of cyclin D1, CDK4, and p21, while the ginkgolide A group presented with a reduced apoptosis rate in comparison with the LPS group (P < 0.05). MiR-224 was the target of ginkgolide A, which had targeted regulatory effects on p21. Ginkgolide A can modulate miR-224 expression and regulate p21 expression in a targeted manner to enhance the resistance of PMVECs to LPS-induced cell apoptosis.