Important Functions and Molecular Mechanisms of Mitochondrial Redox Signaling in Pulmonary Hypertension

Treg Cells Attenuate Pulmonary Venous Remodeling in PH-LHD via NLRC3 Signaling

BACKGROUND

Pulmonary venous remodeling is a key pathological feature of pulmonary hypertension associated with left heart disease (PH-LHD). This study aims to investigate the role of regulatory T (Treg) cells in this process.

METHODS

We used mouse models with transverse aortic constriction and cell depletion of Foxp3-DTR/tdTomato mice to examine Treg cells' function around pulmonary veins in PH-LHD in vivo. To confirm the effect of Nlrc3-/- Treg cells on PH-LHD, we utilized 3 mouse models: Nlrc3 knockout mice, athymic mice, and endothelial cell lineage tracing Cdh5CreERT2+/--mT/mG+/- mice. The interaction proteins and signaling pathways of Treg cells during endothelial-to-mesenchymal transition were elucidated by protein docking prediction, coimmunoprecipitation and cocultivation of Treg cells with venous endothelial cells.

RESULTS

Treg cells were abundant around pulmonary veins of transverse aortic constriction-induced PH-LHD and were essential for promoting inflammation resolution and inhibiting pulmonary venous remodeling. Nlrc3 expression was reduced in mice and patients with PH-LHD. NLRC3 (nucleotide-oligomerization domain-like receptor family CARD domain containing 3) deficiency inhibited Treg cell proliferation and impaired their immunosuppressive and endothelial-to-mesenchymal transition-protective effects. Mechanistically, NLRC3 interacted with TRAM (TRIF-related adaptor molecule) and regulated IRF3/NF-κB (nuclear factor-κB) p65 signaling in CD4+ T cells. NLRC3-deficient Treg cells promoted IL (interleukin)-18 expression through IRF3/NF-κB p65 signaling, and thus IL-18 secretion activated endothelial RTK (receptor tyrosine kinase) signaling, favoring endothelial-to-mesenchymal transition progression in pulmonary veins and PH-LHD progress. This process was reversible with IL-18 binding protein in vivo.

CONCLUSIONS

NLRC3 is crucial for Treg cells to prevent pulmonary venous remodeling in PH-LHD, primarily by modulating IL-18 secretion, which inhibits endothelial-to-mesenchymal transition and thereby improves disease progression and prognosis.

Hypoxia-Induced Mitochondrial ROS and Function in Pulmonary Arterial Endothelial Cells

Pulmonary artery endothelial cells (PAECs) are a major contributor to hypoxic pulmonary hypertension (PH) due to the possible roles of reactive oxygen species (ROS). However, the molecular mechanisms and functional roles of ROS in PAECs are not well established. In this study, we first used Amplex UltraRed reagent to assess hydrogen peroxide (H2O2) generation. The result indicated that hypoxic exposure resulted in a significant increase in Amplex UltraRed-derived fluorescence (i.e., H2O2 production) in human PAECs. To complement this result, we employed lucigenin as a probe to detect superoxide (O2-) production. Our assays showed that hypoxia largely increased O2- production. Hypoxia also enhanced H2O2 production in the mitochondria from PAECs. Using the genetically encoded H2O2 sensor HyPer, we further revealed the hypoxic ROS production in PAECs, which was fully blocked by the mitochondrial inhibitor rotenone or myxothiazol. Interestingly, hypoxia caused an increase in the migration of PAECs, determined by scratch wound assay. In contrast, nicotine, a major cigarette or e-cigarette component, had no effect. Moreover, hypoxia and nicotine co-exposure further increased migration. Transfection of lentiviral shRNAs specific for the mitochondrial Rieske iron-sulfur protein (RISP), which knocked down its expression and associated ROS generation, inhibited the hypoxic migration of PAECs. Hypoxia largely increased the proliferation of PAECs, determined using Ki67 staining and direct cell number accounting. Similarly, nicotine caused a large increase in proliferation. Moreover, hypoxia/nicotine co-exposure elicited a further increase in cell proliferation. RISP knockdown inhibited the proliferation of PAECs following hypoxia, nicotine exposure, and hypoxia/nicotine co-exposure. Taken together, our data demonstrate that hypoxia increases RISP-mediated mitochondrial ROS production, migration, and proliferation in human PAECs; nicotine has no effect on migration, increases proliferation, and promotes hypoxic proliferation; the effects of nicotine are largely mediated by RISP-dependent mitochondrial ROS signaling. Conceivably, PAECs may contribute to PH via the RISP-mediated mitochondrial ROS.

Salidroside enhances NO bioavailability and modulates arginine metabolism to alleviate pulmonary arterial hypertension

BACKGROUND

Salidroside (SAL), derived from Rhodiola, shows protective effects in pulmonary arterial hypertension (PAH) models, but its mechanisms are not fully elucidated.

OBJECTIVES

Investigate the therapeutic effects and the mechanism of SAL on PAH.

METHODS

Monocrotaline was used to establish a PAH rat model. SAL's impact on oxidative stress and inflammatory responses in lung tissues was analyzed using immunohistochemistry, ELISA, and Western blot. Untargeted metabolomics explored SAL's metabolic regulatory mechanisms.

RESULTS

SAL significantly reduced mean pulmonary artery pressure, right ventricular hypertrophy, collagen deposition, and fibrosis in the PAH rats. It enhanced antioxidant enzyme levels, reduced inflammatory cytokines, and improved NO bioavailability by upregulating endothelial nitric oxide synthase (eNOS), soluble guanylate cyclase (sGC), cyclic guanosine monophosphate (cGMP), and protein kinase G (PKG) and decreases the expression of endothelin-1 (ET-1). Metabolomics indicated SAL restored metabolic balance in PAH rats, particularly in arginine metabolism.

CONCLUSIONS

SAL alleviates PAH by modulating arginine metabolism, enhancing NO synthesis, and improving pulmonary vascular remodeling.

o8G Site-Specifically Modified tRF-1-AspGTC: A Novel Therapeutic Target and Biomarker for Pulmonary Hypertension

BACKGROUND

Hypoxia and oxidative stress contribute to the development of pulmonary hypertension (PH). tRNA-derived fragments play important roles in RNA interference and cell proliferation, but their epitranscriptional roles in PH development have not been investigated. We aimed to gain insight into the mechanistic contribution of oxidative stress-induced 8-oxoguanine in pulmonary vascular remodeling.

METHODS

Through small RNA modification array analysis and quantitative polymerase chain reaction, a significant upregulation of the 8-oxoguanine -modified tRF-1-AspGTC was found in the lung tissues and the serum of patients with PH.

RESULTS

This modification occurs at the position 5 of the tRF-1-AspGTC (5o8G tRF). Inhibition of the 5o8G tRF reversed hypoxia-induced proliferation and apoptosis resistance in pulmonary artery smooth muscle cells. Further investigation unveiled that the 5o8G tRF retargeted mRNA of WNT5A (Wingless-type MMTV integration site family, member 5A) and CASP3 (Caspase3) and inhibited their expression. Ultimately, BMPR2 (Bone morphogenetic protein receptor 2) -reactive oxygen species/5o8G tRF/WNT5A signaling pathway exacerbated the progression of PH.

CONCLUSIONS

Our study highlights the role of site-specific 8-oxoguanine-modified tRF in promoting the development of PH. Our findings present a promising therapeutic avenue for managing PH and propose 5o8G tRF as a potential innovative marker for diagnosing this disease.

Biomimetic Integrated Nanozyme for Flare and Recurrence of Gouty Arthritis

Flare and multiple recurrences pose significant challenges in gouty arthritis. Traditional treatments provide temporary relief from inflammation but fail to promptly alleviate patient pain or effectively prevent subsequent recurrences. It should also be noted that both anti-inflammation and metabolism of uric acid are necessary for gouty arthritis, calling for therapeutic systems to achieve these two goals simultaneously. In this study, we propose a biomimetic integrated nanozyme, HMPB-Pt@MM, comprising platinum nanozyme and hollow Prussian blue. It demonstrates anti-inflammatory properties by eliminating reactive oxygen species and reducing infiltration of inflammatory macrophages. Additionally, it rapidly targets inflamed ankles through the camouflage of macrophage membranes. Furthermore, HMPB-Pt@MM exhibits urate oxidase-like capabilities, continuously metabolizing locally elevated uric acid concentrations, ultimately inhibiting multiple recurrences of gouty arthritis. In summary, HMPB-Pt@MM integrates ROS clearance with uric acid metabolism, offering a promising platform for the treatment of gouty arthritis.

Mitochondrial dysfunction following repeated administration of alprazolam causes attenuation of hippocampus-dependent memory consolidation in mice

The frequently repeated administration of alprazolam (Alp), a highly effective benzodiazepine sedative-hypnotic agent, in anxiety, insomnia, and other diseases is closely related to many negative adverse reactions that are mainly manifested as memory impairment. However, the exact molecular mechanisms underlying these events are poorly understood. Therefore, we conducted a proteomic analysis on the hippocampus in mice that received repeated administration of Alp for 24 days. A total of 439 significantly differentially expressed proteins (DEPs) were identified in mice with repeated administration of Alp compared to the control group, and the GO and KEGG analysis revealed the enrichment of terms related to mitochondrial function, cycle, mitophagy and cognition. In vitro experiments have shown that Alp may affect the cell cycle, reduce the mitochondrial membrane potential (MMP) to induce apoptosis in HT22 cells, and affect the progress of mitochondrial energy metabolism and morphology in the hippocampal neurons. Furthermore, in vivo behavioral experiments including IntelliCage System (ICS) and nover object recognition (NOR), hippocampal neuronal pathological changes with HE staining, and the expression levels of brain-deprived neuron factor (BDNF) with immunohistochemistry showed a significant decrease in memory consolidation in mice with repeated administration of Alp, which could be rescued by the co-administration of the mitochondrial protector NSI-189. To the best of our knowledge, this is the first study to identify a link between repeated administration of Alp and mitochondrial dysfunction and that mitochondrial impairment directly causes the attenuation of memory consolidation in mice.

Pitfalls of Mitochondrial Redox Signaling Research

Redox signaling from mitochondria (mt) to the cytosol and plasma membrane (PM) has been scarcely reported, such as in the case of hypoxic cell adaptation or (2-oxo-) 2-keto-isocaproate (KIC) β-like-oxidation stimulating insulin secretion in pancreatic β-cells. Mutual redox state influence between mitochondrial major compartments, the matrix and the intracristal space, and the cytosol is therefore derived theoretically in this article to predict possible conditions, when mt-to-cytosol and mt-to-PM signals may occur, as well as conditions in which the cytosolic redox signaling is not overwhelmed by the mitochondrial antioxidant capacity. Possible peroxiredoxin 3 participation in mt-to-cytosol redox signaling is discussed, as well as another specific case, whereby mitochondrial superoxide release is diminished, whereas the matrix MnSOD is activated. As a result, the enhanced conversion to H2O2 allows H2O2 diffusion into the cytosol, where it could be a predominant component of the H2O2 release. In both of these ways, mt-to-cytosol and mt-to-PM signals may be realized. Finally, the use of redox-sensitive probes is discussed, which disturb redox equilibria, and hence add a surplus redox-buffering to the compartment, where they are localized. Specifically, when attempts to quantify net H2O2 fluxes are to be made, this should be taken into account.

In Vitro Cell Death Mechanisms Induced by Dicoma anomala Root Extract in Combination with ZnPcS4 Mediated-Photodynamic Therapy in A549 Lung Cancer Cells

Globally, lung cancer has remained the leading cause of morbidity and mortality in men and women. To enhance photodynamic therapeutic effects in vitro, the present study was designed to reduce dose-dependence in photodynamic therapy (PDT) and evaluate the anticancer effects of Dicoma anomala (D. anomala) root extracts (i.e., chloroform (Chl), ethyl acetate (EtOAc), and methanol (MeOH)) on A549 lung cancer cells. The most active extract of D. anomala (D.A) was used to establish the 50% inhibitory concentration (IC₅₀), which was further used to evaluate the anticancer efficacy of D.A in combination with ZnPcS₄-mediated PDT IC₅₀. The study further evaluated cell death mechanisms by cell viability/ cytotoxicity (LIVE/DEAD^TM assay), flow cytometry (Annexin V-fluorescein isothiocyanate (FITC)-propidium iodide (PI) staining), immunofluorescence (p38, p53, Bax, and caspase 3 expressions), and fluorometric multiplex assay (caspase 8 and 9) 24 h post-treatment with IC₅₀ concentrations of ZnPcS₄-mediated PDT and D.A MeOH root extract. Morphological changes were accompanied by a dose-dependent increase in cytotoxicity, decrease in viability, and proliferation in all experimental models. Apoptosis is the highly favored cell death mechanism observed in combination therapy groups. Apoptotic activities were supported by an increase in the number of dead cells in the LIVE/DEAD^TM assay, and the upregulation of p38, p53, Bax, caspase 3, 8, and 9 apoptotic proteins. In vitro experiments confirmed the cytotoxic and antiproliferative effects of D.A root extracts in monotherapy and in combination with ZnPcS₄-mediated PDT. Taken together, our findings demonstrated that D.A could be a promising therapeutic candidate worth exploring in different types of cancer.

The Impact of General Anesthesia on Redox Stability and Epigenetic Inflammation Pathways: Crosstalk on Perioperative Antioxidant Therapy

Worldwide, the prevalence of surgery under general anesthesia has significantly increased, both because of modern anesthetic and pain-control techniques and because of better diagnosis and the increased complexity of surgical techniques. Apart from developing new concepts in the surgical field, researchers and clinicians are now working on minimizing the impact of surgical trauma and offering minimal invasive procedures due to the recent discoveries in the field of cellular and molecular mechanisms that have revealed a systemic inflammatory and pro-oxidative impact not only in the perioperative period but also in the long term, contributing to more difficult recovery, increased morbidity and mortality, and a negative financial impact. Detailed molecular and cellular analysis has shown an overproduction of inflammatory and pro-oxidative species, responsible for augmenting the systemic inflammatory status and making postoperative recovery more difficult. Moreover, there are a series of changes in certain epigenetic structures, the most important being the microRNAs. This review describes the most important molecular and cellular mechanisms that impact the surgical patient undergoing general anesthesia, and it presents a series of antioxidant therapies that can reduce systemic inflammation.

The Potential Important Role of Mitochondrial Rieske Iron-Sulfur Protein as a Novel Therapeutic Target for Pulmonary Hypertension in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide, which is often due to pulmonary hypertension (PH). The underlying molecular mechanisms are poorly understood, and current medications are neither specific nor always effective. In this review, we highlight the recent findings on the roles of altered mitochondrial bioenergetics in PH in COPD. We also discuss the central role of mitochondrial reactive oxygen species (ROS) generation mediated by Rieske iron-sulfur protein (RISP) and review the contributions of RISP-dependent DNA damage and NF-κB-associated inflammatory signaling. Finally, the potential importance of mitochondrial RISP and its associated molecules as novel therapeutic targets for PH in COPD are meticulously discussed.