Terretonin as a New Protective Agent against Sepsis-Induced Acute Lung Injury: Impact on SIRT1/Nrf2/NF-κBp65/NLRP3 Signaling

Nicotinamide mononucleotide alleviates endotoxin-induced acute lung injury by modulating macrophage polarization via the SIRT1/NF-κB pathway

CONTEXT

Sepsis-induced acute lung injury (ALI) is a severe condition with limited effective therapeutics; nicotinamide mononucleotide (NMN) has been reported to exert anti-inflammatory activities.

OBJECTIVE

This study explores the potential mechanisms by which NMN ameliorates sepsis-induced ALI in vivo and in vitro.

MATERIALS AND METHODS

Cultured MH-S cells and a murine model were used to evaluate the effect of NMN on sepsis-induced ALI. MH-S cells were stimulated with LPS (1 μg/mL) and NMN (500 μM) for 12 h grouping as control, LPS, and LPS + NMN. Cell viability, apoptotic status, and M1/2 macrophage-related markers were detected. The mice were pretreated intraperitoneally with NMN (500 mg/kg) and/or EX-527 (5 mg/kg) 1 h before LPS injection and randomized into 7 groups (n = 8): control, LPS, LPS + NMN, NMN, LPS + NMN + EX-527 (a SIRT1 inhibitor), LPS + EX-527, and EX-527. After 12 h, lung histopathology, W/D ratio, MPO activity, NAD+ and ATP levels, M1/2 macrophage-related markers, and expression of the SIRT1/NF-κB pathway were detected.

RESULTS

In MH-S cells, NMN significantly decreased the apoptotic rate from 12.25% to 5.74%. In septic mice, NMN improved the typical pathologic findings in lungs and reduced W/D ratio and MPO activity, but increased NAD+ and ATP levels. Additionally, NMN suppressed M1 but promoted M2 polarization, and upregulated the expression of SIRT1, with inhibition of NF-κB-p65 acetylation and phosphorylation. Furthermore, inhibition of SIRT1 reversed the effects of NMN-induced M2 macrophage polarization.

CONCLUSIONS

NMN protects against sepsis-induced ALI by promoting M2 macrophage polarization via the SIRT1/NF-κB pathway, it might be an effective strategy for preventing or treating sepsis-induced ALI.

R. Almalki N, Asfour HZ, Al-Rabia MW, Alzain AA, Mohamed GA, Ibrahim SR. Protective effect of kaempferol glucoside against lipopolysaccharide-caused acute lung injury via targeting Nrf2/NF-κB/NLRP3/GSDMD: Integrating experimental and computational studies

The current study explored the protective potential of kaempferol 3-sophoroside-7-glucoside (KSG) against acute lung injury (ALI). Pre-treatment with KSG effectively secured mice from ALI and showed similar efficaciousness to dexamethasone. KSG markedly increased the survival rate and alleviated lung pathological lesions induced by lipopolysaccharide (LPS). Furthermore, KSG attenuated differential and total cell counts in BALF (bronchoalveolar lavage fluid) and MPO (myeloperoxidase) activity. KSG counteracted the NF-κB (nuclear factor-κB) activation and significantly ameliorated the downstream inflammatory cytokine, TNF-α (tumor necrosis factor-α). Simultaneously, KSG suppressed the over-expression of NLRP3 (NOD-like receptor protein 3), caspase-1, and pro-inflammatory cytokine interleukin IL-1β (interleukine-1β) and prohibited the elevation of the pyroptotic parameter GSDMD-N (N-terminal domain of gasdermin D) induced by LPS challenge. In addition, KSG significantly enhanced Nrf2 (nuclear-factor erythroid-2-related factor) and HO-1 (heme-oxygenase-1) expression. Meanwhile, KSG mitigated lipid peroxidative markers (malondialdehyde, protein carbonyl and 4-hydroxynonenal) and boosted endogenous antioxidants (superoxide dismutase/reduced glutathione/catalase) in lung tissue. In silico analyses revealed that KSG disrupts Keap1-Nrf2 protein-protein interactions by binding to the KEAP1 domain, consequently activating Nrf2. Specifically, molecular docking demonstrated superior binding affinity of KSG to KEAP1 compared to the reference inhibitor, with docking scores of -9.576 and -6.633 Kcal/mol, respectively. Additionally, the MM-GBSA binding free energy of KSG (-67.25 Kcal/mol) surpassed that of the reference inhibitor (-56.36 Kcal/mol). Furthermore, MD simulation analysis revealed that the KSG-KEAP1 complex exhibits substantial and stable binding interactions with various amino acids over a duration of 100 ns. These findings showed the protective anti-inflammatory and anti-oxidative modulatory efficiencies of KSG that effectively counteracted LPS-induced ALI and encouraged future research and clinical applications of KSG as a protective strategy for ALI.

Mechanisms of Sepsis-Induced Acute Lung Injury and Advancements of Natural Small Molecules in Its Treatment

Sepsis-induced acute lung injury (ALI), characterized by widespread lung dysfunction, is associated with significant morbidity and mortality due to the lack of effective pharmacological treatments available clinically. Small-molecule compounds derived from natural products represent an innovative source and have demonstrated therapeutic potential against sepsis-induced ALI. These natural small molecules may provide a promising alternative treatment option for sepsis-induced ALI. This review aims to summarize the pathogenesis of sepsis and potential therapeutic targets. It assembles critical updates (from 2014 to 2024) on natural small molecules with therapeutic potential against sepsis-induced ALI, detailing their sources, structures, effects, and mechanisms of action.

Therapeutic potential of HUC-MSC-exos primed with IFN-γ against LPS-induced acute lung injury

Objectives

Human umbilical cord mesenchymal stem cells (HUC-MSCs) are pluripotent stem cells with anti-inflammatory and immunomodulatory properties used in the treatment of acute lung injury (ALI). However, the treatment of ALI using exosomes derived from HUC-MSCs (HUC-MSC-exos) primed with interferon-gamma (IFN-γ-exos) has not been described. This study investigated the effects of IFN-γ-exos on ALI.

Materials and Methods

IFN-γ primed and unprimed HUC-MSC-exos (IFN-γ-exos and CON-exos, respectively) were extracted, identified, and traced. A549 cells and mice subjected to lipopolysaccharide (LPS)-induced inflammation were treated with IFN-γ-exos or CON-exos. Viability; interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and reactive oxygen species (ROS) levels; NF-κB p65, and NLRP3 expression and histology and lung injury scores were measured in cell, supernatant or lung tissue.

Results

Indoleamine 2,3-dioxygenase (IDO) mRNA expression was elevated in HUC-MSCs primed with 5 ng/mL IFN-γ (P<0.001), and IFN-γ-exos and CON-exos were successfully extracted. LPS-induced inflammation resulted in decreased cell viability in A549 cells, and increased IL-1β, IL-6, TNF-α and ROS levels and NF-κB p65 and NLRP3 expression in A549 cells and mice(P<0.05 to P<0.001). Treatment with IFN-γ-exos and CON-exos increased cell viability and decreased the concentrations of IL-1β, and ROS, expression of NF-κB p65 and NLRP3, and the lung injury score, and these effects were more obvious for IFN-γ-exos(P<0.05 to P<0.001).

Conclusion

IFN-γ-exos reduced oxidative stress and inflammatory responses in LPS-induced A549 cells and mice. The result demonstrated the therapeutic potential of IFN-γ-exos in LPS-induced ALI.

Sepsis-Induced Acute Lung Injury Is Alleviated by Small Molecules from Dietary Plants via Pyroptosis Modulation

Sepsis-induced acute respiratory distress syndrome (ARDS) has high morbidity and mortality, and it has three major pathogeneses, namely alveolar-capillary barrier destruction, elevated gut permeability, and reduced neutrophil extracellular traps (NETS), all of which are pyroptosis-involved. Due to limitations of current agents like adverse reaction superposition, inevitable drug resistance, and relatively heavier financial burden, naturally extracted small-molecule compounds have a broad market even though chemically modified drugs have straightforward efficacy. Despite increased understanding of the molecular biology and mechanism underlying sepsis-induced ARDS, there are no specific reviews concerning how small molecules from dietary plants alleviate sepsis-induced acute lung injury (ALI) via regulating pyroptotic cell death. Herein, we traced and reviewed the molecular underpinnings of sepsis-induced ALI with a focus on small-molecule compounds from dietary plants, the top three categories of which are respectively flavonoids and flavone, terpenoids, and polyphenol and phenolic acids, and how they rescued septic ALI by restraining pyroptosis.

Involvement of the SIRT1-NLRP3 pathway in the inflammatory response

The silent information regulator 2 homolog 1-NACHT, LRR and PYD domains-containing protein 3 (SIRT1-NLRP3) pathway has a crucial role in regulation of the inflammatory response, and is closely related to the occurrence and development of several inflammation-related diseases. NLRP3 is activated to produce the NLRP3 inflammasome, which leads to activation of caspase-1 and cleavage of pro-interleukin (IL)-1β and pro-IL-18 to their active forms: IL-1β and IL-18, respectively. They are proinflammatory cytokines which then cause an inflammatory response.SIRT1 can inhibit this inflammatory response through nuclear factor erythroid 2-related factor 2 and nuclear factor-kappa B pathways. This review article focuses mainly on how the SIRT1-NLRP3 pathway influences the inflammatory response and its relationship with melatonin, traumatic brain injury, neuroinflammation, depression, atherosclerosis, and liver damage. Video Abstract.

Docking and Molecular Dynamic Investigations of Phenylspirodrimanes as Cannabinoid Receptor-2 Agonists

Cannabinoid receptor ligands are renowned as being therapeutically crucial for treating diverse health disorders. Phenylspirodrimanes are meroterpenoids with unique and varied structural scaffolds, which are mainly reported from the Stachybotrys genus and display an array of bioactivities. In this work, 114 phenylspirodrimanes reported from Stachybotrys chartarum were screened for their CB2 agonistic potential using docking and molecular dynamic simulation studies. Compound 56 revealed the highest docking score (-11.222 kcal/mol) compared to E3R_6KPF (native agonist, gscore value -12.12 kcal/mol). The molecular docking and molecular simulation results suggest that compound 56 binds to the putative binding site in the CB2 receptor with good affinity involving key interacting amino acid residues similar to that of the native ligands, E3R. The molecular interactions displayed π-π stacking with Phe183 and hydrogen bond interactions with Thr114, Leu182, and Ser285. These findings identified the structural features of these metabolites that might lead to the design of selective novel ligands for CB2 receptors. Additionally, phenylspirodrimanes should be further investigated for their potential as a CB2 ligand.

MiR-362-5p inhibits cartilage repair in osteoarthritis via targeting plexin B1

BACKGROUND AND OBJECTIVES

Chondrogenesis of bone marrow mesenchymal stem cells (BMSCs) exerts great function during the pathogenesis of osteoarthritis (OA). Studies have reported the association of plexin B1 (PLXNB1) with OA pathogenesis. In this study, the upstream mechanism and function of PLXNB1 in this disease were explored.

METHODS

Flow cytometry was applied to test BMSC characterization. Chondrogenic differentiation of BMSCs was evaluated by Alcian blue staining. The expression of PLXNB1, miR-362-5p, miR-501-5p, miR-1827, miR-500-5p was measured using RT-qPCR analysis. The protein levels of PLXNB1, Aggrecan, and Silent information regulator factor 2-related enzyme 1 (SIRT1) were determined by western blotting. Binding relationship between miR-362-5p and PLXNB1 was confirmed using bioinformatics analysis and luciferase reporter assay. The in vivo model of OA was established in Sprague-Dawley rats which received medial meniscus instability surgery. For histopathological examination, cartilage tissues in the knee joint of rats were stained with hematoxylin and eosin. Micro-CT analysis was employed to observe the changes of morphometric indices including average trabecular separation, average trabecular thickness, and bone volume fraction.

RESULTS

BMSCs were identified to possess the characteristics of mesenchymal stem cells. PLXNB1 was observed to be highly expressed during chondrogenic differentiation of BMSCs and PLXNB1 overexpression promoted BMSC chondrogenic differentiation. Mechanically, PLXNB1 was targeted by miR-362-5p. In rescue assays, miR-362-5p reversed the effects of PLXNB1 on chondrogenic differentiation of BMSCs. In the in vivo experiments, upregulated PLXNB1 expression alleviated joint injury of OA rats. Additionally, overexpressed miR-362-5p and downregulated PLXNB1 expression levels were detected in OA rats.

CONCLUSION

MiR-362-5p promotes OA progression by suppressing PLXNB1.

Nrf2 Deficiency Exacerbated CLP-Induced Pulmonary Injury and Inflammation through Autophagy- and NF-κB/PPARγ-Mediated Macrophage Polarization

The balance between M1 and M2 macrophage polarization is involved in the regulation of pulmonary inflammation. Nuclear factor erythroid-derived 2-like 2 (Nfe2l2, also known as Nrf2), a nuclear transcription factor, is reported to play protective roles in acute lung injury (ALI) and inflammation, and increasing evidence indicates that the protective effects of Nrf2 are closely related to autophagy. This study aimed to explore whether Nrf2 is involved in sepsis-induced acute pulmonary injury and inflammation and in the role of macrophage polarization in the process. In the present study, sepsis patients, an Nrf2 knockout mouse that underwent cecal ligation and puncture (CLP), and lipopolysaccharide (LPS)-treated macrophage cell lines were employed to investigate the potential functions of Nrf2 in sepsis-induced lung injury and the underlying mechanisms. Clinical studies showed that the NRF2 mRNA level was inversely correlated with pulmonary inflammation and disease severity in patients with sepsis. Analyses in a CLP-treated Nrf2 knockout mouse model indicated that an Nrf2 deficiency promoted a CLP-induced increase in M1 macrophage polarization and apoptosis and inhibited CLP-induced upregulation of the autophagy level in lung tissues. Experiments in RAW264.7 cells revealed that Nrf2 overexpression inhibited M1 macrophage polarization but promoted M2 macrophage polarization by improving the autophagy, and Nrf2 overexpression promoted PPARγ but inhibited NF-κB nuclear translocation. In conclusion, these results indicate that Nrf2 plays a protective role in sepsis-induced pulmonary injury and inflammation through the regulation of autophagy- and NF-κB/PPARγ-mediated macrophage polarization.

The protective effect of natural medicines against excessive inflammation and oxidative stress in acute lung injury by regulating the Nrf2 signaling pathway

Acute lung injury (ALI) is a common critical disease of the respiratory system that progresses into acute respiratory distress syndrome (ARDS), with high mortality, mainly related to pulmonary oxidative stress imbalance and severe inflammation. However, there are no clear and effective treatment strategies at present. Nuclear factor erythroid 2-related factor 2(Nrf2) is a transcription factor that interacts with multiple signaling pathways and regulates the activity of multiple oxidases (NOX, NOS, XO, CYP) related to inflammation and apoptosis, and exhibits antioxidant and anti-inflammatory roles in ALI. Recently, several studies have reported that the active ingredients of natural medicines show protective effects on ALI via the Nrf2 signaling pathway. In addition, they are cheap, naturally available, and possess minimal toxicity, thereby having good clinical research and application value. Herein, we summarized various studies on the protective effects of natural pharmaceutical components such as polyphenols, flavonoids, terpenoids, alkaloids, and polysaccharides on ALI through the Nrf2 signaling pathway and demonstrated existing gaps as well as future perspectives.

Cucurbitacin E glucoside alleviates concanavalin A-induced hepatitis through enhancing SIRT1/Nrf2/HO-1 and inhibiting NF-ĸB/NLRP3 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Cucurbitacins are highly oxygenated tetracyclic triterpenoids, that represent the major metabolites reported from C. colocynthis (L.) Schrad.. Cucurbitacin E glucoside (CuE) is a tetracyclic triterpene glycoside separated from Cucurbitaceae plants. CuE has potent anti-inflammatory, immunomodulatory, and anti-tumor properties.

AIM OF THE STUDY

The current study aimed at examining the hepatoprotective effect of CuE against concanavalin A (Con A)-produced hepatitis.

MATERIALS AND METHODS

Mice were intravenously administered Con A (15 mg/kg) to induce AIH. CuE was orally administered at two different doses for five days preceding Con A injection.

RESULTS

The results revealed that CuE pretreatment markedly attenuated the serum indices of hepatotoxicity and the severity of hepatic lesions. CuE depressed Con A-provoked increment in CD4⁺ T-cells in hepatic tissue. The antioxidant activity of CuE was evident through its ability to decrease markers of Con A-induced oxidative stress (malondialdehyde, 4-hydroxyenonanal, and protein carbonyl) and intensified the antioxidants in the hepatic tissue (SOD, GSH, and TAC). CuE increased mRNA expression of SIRT1 and Nrf2 as well as its binding capacity. Subsequently, CuE augmented mRNA expression of Nrf2 targeted genes as NQO1, GCL, and HO-1 and recovered its normal level. CuE inhibited the activation of NF-κB/downstream pro-inflammatory mediators signaling. Furthermore, CuE attenuated the mRNA expression of NLRP3 and its associated genes.

CONCLUSION

Collectively, these results demonstrated the remarkable hepatoprotective potential of CuE towards Con A-induced AIH which was mediated via suppression of oxidative stress, enhancing SIRT1/Nrf2/HO-1, and prohibition of the NF-κB/NLRP3 signaling. CuE could be a candidate for hepatitis patients.

Fungal Naphthalenones; Promising Metabolites for Drug Discovery: Structures, Biosynthesis, Sources, and Pharmacological Potential

Fungi are well-known for their abundant supply of metabolites with unrivaled structure and promising bioactivities. Naphthalenones are among these fungal metabolites, that are biosynthesized through the 1,8-dihydroxy-naphthalene polyketide pathway. They revealed a wide spectrum of bioactivities, including phytotoxic, neuro-protective, cytotoxic, antiviral, nematocidal, antimycobacterial, antimalarial, antimicrobial, and anti-inflammatory. The current review emphasizes the reported naphthalenone derivatives produced by various fungal species, including their sources, structures, biosynthesis, and bioactivities in the period from 1972 to 2021. Overall, more than 167 references with 159 metabolites are listed.

Chaetomugilins and Chaetoviridins—Promising Natural Metabolites: Structures, Separation, Characterization, Biosynthesis, Bioactivities, Molecular Docking and Molecular Dynamics

Fungi are recognized as luxuriant metabolic artists that generate propitious biometabolites. Historically, fungal metabolites have largely been investigated as leads for various therapeutic agents. Chaetomugilins and the closely related chaetoviridins are fungal metabolites, and each has an oxygenated bicyclic pyranoquinone core. They are mainly produced by various Chaetomaceae species. These metabolites display unique chemical features and diversified bioactivities. The current review gives an overview of research about fungal chaetomugilins and chaetoviridins regarding their structures, separation, characterization, biosynthesis, and bioactivities. Additionally, their antiviral potential towards the SARS-CoV-2 protease was evaluated using docking studies and molecular dynamics (MD) simulations. We report on the docking and predictive binding energy estimations using reported crystal structures of the main protease (PDB ID: 6M2N, 6W81, and 7K0f) at variable resolutions—i.e., 2.20, 1.55, and 1.65 Å, respectively. Chaetovirdin D (43) exhibited highly negative docking scores of −7.944, −8.141, and −6.615 kcal/mol, when complexed with 6M2N, 6W81, and 7K0f, respectively. The reference inhibitors exhibited the following scores: −5.377, −6.995, and −8.159 kcal/mol, when complexed with 6M2N, 6W81, and 7K0f, respectively. By using molecular dynamics simulations, chaetovirdin D’s stability in complexes with the viral protease was analyzed, and it was found to be stable over the course of 100 ns.