The protective effects of orexin a against high glucose-induced activation of NLRP3 inflammasome in human vascular endothelial cells

Trigeminal nerve electrical stimulation attenuates early traumatic brain injury through the TLR4/NF-κB/NLRP3 signaling pathway mediated by orexin-A/OX1R system

BACKGROUND

Traumatic brain injury (TBI) is a significant contributor to global mortality and disability, and emerging evidence indicates that trigeminal nerve electrical stimulation (TNS) is a promising therapeutic intervention for neurological impairment following TBI. However, the precise mechanisms underlying the neuroprotective effects of TNS in TBI are poorly understood. Thus, the objective of this study was to investigate the potential involvement of the orexin-A (OX-A)/orexin receptor 1 (OX1R) mediated TLR4/NF-κB/NLRP3 signaling pathway in the neuroprotective effects of TNS in rats with TBI.

METHODS

Sprague-Dawley rats were randomly assigned to four groups: sham, TBI, TBI+TNS+SB334867, and TBI+TNS. TBI was induced using a modified Feeney's method, and subsequent behavioral assessments were conducted to evaluate neurological function. The trigeminal nerve trunk was isolated, and TNS was administered following the establishment of the TBI model. The levels of neuroinflammation, brain tissue damage, and proteins associated with the OX1R/TLR4/NF-κB/NLRP3 signaling pathway were assessed using hematoxylin-eosin staining, Nissl staining, western blot analysis, quantitative real-time polymerase chain reaction, and immunofluorescence techniques.

RESULTS

The findings of our study indicate that TNS effectively mitigated tissue damage, reduced brain edema, and alleviated neurological deficits in rats with TBI. Furthermore, TNS demonstrated the ability to attenuate neuroinflammation levels and inhibit the expression of proteins associated with the TLR4/NF-κB/NLRP3 signaling pathway. However, it is important to note that the aforementioned effects of TNS were reversible upon intracerebroventricular injection of an OX1R antagonist.

CONCLUSION

TNS may prevent brain damage and relieve neurological deficits after a TBI by inhibiting inflammation, possibly via the TLR4/NF-κB/NLRP3 signaling pathway mediated by OX-A/OX1R.

Local glucose elevation activates pyroptosis via NLRP3 inflammasome in ovarian granulosa cells of overweight patients

Overweight, with an increasing prevalence worldwide, significantly impairs the clinical outcomes following in vitro fertilization (IVF). Hyperglycemia, hyperlipidemia, and metabolic disorders are always accompanied by the majority of overweight patients. The association between granulosa cell function and metabolic alterations in follicular fluid including lipids, proteins, and growth factors has been extensively documented. However, the effects of higher glucose level on ovarian granulosa cells (GCs), remain largely unknown. In this study, we identified that overweight women had elevated follicular glucose level which profoundly activated NLRP3 inflammasome and pyroptosis. An in vitro correlation between follicular high glucose, NLRP3 inflammasome and pyroptosis was also established. More importantly, in granulosa cells of overweight patients, the activation of the NLRP3 inflammasome and pyroptosis induced by high glucose was involved in the dysregulation of estradiol synthesis. Our study may provide new options to interpretate and improve IVF outcomes in overweight women.

Research progress on the mechanism of aging of vascular endothelial cells and the intervention of traditional Chinese medicine: A review

Vascular senescence is the basic factor of many cardiovascular diseases. Vascular endothelium, as a protective barrier between blood and vascular wall, plays an important role in maintaining the integrity and homeostasis of vascular system. Endothelial cell senescence is an important pathological change of vascular senescence. In recent years, more and more studies have been conducted on vascular endothelial cell senescence, especially on its mechanism. Many research results showed that the mechanism is various, but the systematic elucidation still lacks. Western medicine has little choice in the prevention and treatment of endothelial cell senescence, and the control effect is also limited, while Chinese medicine makes up for the deficiency in this regard. The main mechanisms of vascular endothelial cell aging and the related research progress of traditional Chinese medicine in the prevention and treatment of vascular endothelial aging in recent years were summarized in this paper to provide reference for the research of traditional Chinese medicine in anti-vascular aging and the prevention and treatment of cardiovascular disease.

Protective Effects of Orexin A in a Murine Model of Cisplatin-Induced Acute Kidney Injury

Cisplatin is a chemotherapeutic agent widely used in the treatment of various cancers, but its application is often limited due to complications such as acute kidney injury (AKI). Orexins are hypothalamic neuropeptides that modulate the sleep-wake cycle, neuroendocrine function, and the autonomic nervous system. Emerging evidence suggests that orexin A (OXA) has anti-inflammatory and neuroprotective effects in animal models of neuroinflammatory diseases of the central nervous system. However, the effect of OXA on kidney diseases has not been examined. Here, we investigated whether OXA has a protective effect in a murine model of cisplatin-induced AKI. Intraperitoneal administration of OXA ameliorated renal dysfunction, and histological abnormalities in mice injected with cisplatin. OXA inhibited cisplatin-induced oxidative stress through the modulation of prooxidant and antioxidant enzymes. This peptide reduced apoptotic cell death by inhibiting the p53-mediated pathway in mice injected with cisplatin. OXA also alleviated cisplatin-induced cytokine production and macrophage infiltration into injured kidneys. Taken together, these results showed that OXA ameliorates cisplatin-induced AKI via antioxidant, anti-apoptotic, and anti-inflammatory actions. This peptide could be a potential therapeutic agent for cisplatin-induced AKI.

Orexin/hypocretin system dysfunction in patients with Takotsubo syndrome: A novel pathophysiological explanation

Takotsubo syndrome (TTS) is an acute heart failure syndrome. Emotional or physical stressors are believed to precipitate TTS, while the pathophysiological mechanism is not yet completely understood. During the coronavirus disease (COVID-19) pandemic, an increased incidence of TTS has been reported in some countries; however, the precise pathophysiological mechanism for developing TTS with acute COVID-19 infection is unknown. Nevertheless, observing the symptoms of COVID-19 might lead to new perspectives in understanding TTS pathophysiology, as some of the symptoms of the COVID-19 infection could be assessed in the context of an orexin/hypocretin-system dysfunction. Orexin/hypocretin is a cardiorespiratory neuromodulator that acts on two orexin receptors widely distributed in the brain and peripheral tissues. In COVID-19 patients, autoantibodies against one of these orexin receptors have been reported. Orexin-system dysfunction affects a variety of systems in an organism. Here, we review the influence of orexin-system dysfunction on the cardiovascular system to propose its connection with TTS. We propose that orexin-system dysfunction is a potential novel explanation for the pathophysiology of TTS due to direct or indirect dynamics of orexin signaling, which could influence cardiac contractility. This is in line with the conceptualization of TTS as a cardiovascular syndrome rather than merely a cardiac abnormality or cardiomyopathy. To the best of our knowledge, this is the first publication to present a plausible connection between TTS and orexin-system dysfunction. We hope that this novel hypothesis will inspire comprehensive studies regarding orexin's role in TTS pathophysiology. Furthermore, confirmation of this plausible pathophysiological mechanism could contribute to the development of orexin-based therapeutics in the treatment and prevention of TTS.

Low-intensity focused ultrasound attenuates early traumatic brain injury by OX-A/NF-κB/NLRP3 signaling pathway

Background: Traumatic brain injury (TBI) is a serious hazard to human health and is characterized by high rates of disability and mortality. It is necessary to explore new effective treatment methods to reduce the impact of TBI on individuals and society. As an emerging neuromodulation technique, ultrasound is used to treat some neurological diseases, but the neuroprotective mechanism of low-intensity focused ultrasound (LIFUS) in TBI remains unclear. We aimed to investigate the protective effects and potential mechanisms of LIFUS in TBI.

Methods: A rat model of TBI was established using the free-fall method. After establishing the TBI model, the hypothalamus region was covered with LIFUS radiation, and an orexin receptor 1 (OXR1) antagonist (SB334867) was injected intraperitoneally. Neurobehavioral examination, Nissl staining, hematoxylin and eosin staining of the brain tissue, and brain water content, were performed 3 days later. Western blotting, quantitative real-time polymerase chain reaction, immunofluorescence staining, and immunohistochemical staining, were used to evaluate the neuroprotective mechanisms of LIFUS.

Results: LIFUS improved tissue damage, neurological deficits, and brain edema. LIFUS can increase the expression of orexin-A (OX-A) and OXR1, significantly inhibit the activation of nuclear factor-κB (NF-κB) protein and nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome after TBI, and reduce the release of pro-inflammatory factors after TBI; however, SB334867 can reverse this effect.

Conclusions: This study suggests that LIFUS may play a neuroprotective role by promoting the release of OX-A from the hypothalamus and inhibiting the inflammatory response after TBI through the OX-A /NF-κB/NLRP3 pathway.

Effects of caffeine ingestion and thermotherapy on blood orexin circulation in humans

Caffeine and orexin can affect awakening, neuroendocrine, and sympathetic nerve function. Our previous study has reported that caffeine intake can increase human body temperature. However, little is known about the combined effects of thermotherapy and caffeine intake on human serum orexin concentrations. Forty-two healthy male subjects with age of 26.72 ± 5.05 years, height of 174.10 ± 7.09 cm, and body weight of 74.68 ± 8.91 kg participated in this study. They were randomly assigned to a control (CON) group (n = 21) and a caffeine (CAFF) group (n = 21). After thermotherapy (half-body immersion in a hot water bath at 42 ± 0.5 °C, circulating orexin level increased more (p < 0.05) in the CAFF group than in the CON group. Positive relationships between mean body temperature and orexin were observed before and after heat stimulation (p < 0.001). Caffeine intake boosted the upregulation of serum orexin concentrations in subjects undergoing thermotherapy.

Large-leaf yellow tea attenuates high glucose-induced vascular endothelial cells injury by up-regulating autophagy and down-regulating oxidative stress

Vascular endothelial cells injury induced by high glucose (HG) plays an important role in the occurrence and development of diabetic vascular complications. Yellow tea has a protective effect on vascular...

Effects of Orexin B on Swine Granulosa and Endothelial Cells

Simple Summary

The follicle is the ovarian functional unit. It is mainly composed of granulosa cells and angiogenesis is crucial to guarantee its development till ovulation. Carrying on our previous studies on the orexin system in the ovary, we presently demonstrate a potential role of orexin B in the control of granulosa cells’ oxidative stress and of the angiogenesis event.

Abstract

In addition to the well-known central modulatory role of orexins, we recently demonstrated a peripheral involvement in swine granulosa cells for orexin A and in adipose tissue for orexin B (OXB). The aim of present research was to verify immunolocalization of OXB and its potential role in modulating the main features of swine granulosa cells. In particular, we explored the effects on granulosa cell proliferation (through the incorporation of bromodeoxyuridine), cell metabolic activity (as indirect evaluation by the assessment of ATP), steroidogenic activity (by immunoenzymatic examination) and redox status (evaluating the production of superoxide anion by means of the WST test, production of nitric oxide through the use of the Griess test and the non-enzymatic reducing power by FRAP test). Our data point out that OXB does not modify granulosa cell growth, steroidogenesis and superoxide anion generation. On the contrary, the peptide stimulates (p < 0.05) nitric oxide output and non-enzymatic reducing power. Since new vessel growth is crucial for ovarian follicle development, a further aim of this study was to explore the expression of prepro-orexin and the effects of OXB on swine aortic endothelial cells. We found that the peptide is ineffective in modulating cell growth, while it inhibits redox status parameters. In addition, we demonstrated a stimulatory effect on angiogenesis evaluated in fibrin gel angiogenesis assay. Taken together, OXB appears to be potentially involved in the modulation of redox status in granulosa and endothelial cells and we could argue an involvement of the peptide in the follicular angiogenic events.

Intranasal insulin and orexins to treat age-related cognitive decline

The intranasal (IN) administration of neuropeptides, such as insulin and orexins, has been suggested as a treatment strategy for age-related cognitive decline (ARCD). Because dysfunctional neuropeptide signaling is an observed characteristic of ARCD, it has been suggested that IN delivery of insulin and/or orexins may restore endogenous peptide signaling and thereby preserve cognition. IN administration is particularly alluring as it is a relatively non-invasive method that directly targets peptides to the brain. Several laboratories have examined the behavioral effects of IN insulin in young, aged, and cognitively impaired rodents and humans. These studies demonstrated improved performance on various cognitive tasks following IN insulin administration. Fewer laboratories have assessed the effects of IN orexins; however, this peptide also holds promise as an effective treatment for ARCD through the activation of the cholinergic system and/or the reduction of neuroinflammation. Here, we provide a brief overview of the advantages of IN administration and the delivery pathway, then summarize the current literature on IN insulin and orexins. Additional preclinical studies will be useful to ultimately uncover the mechanisms underlying the pro-cognitive effects of IN insulin and orexins, whereas future clinical studies will aid in the determination of the most efficacious dose and dosing paradigm. Eventually, IN insulin and/or orexin administration may be a widely used treatment strategy in the clinic for ARCD.

The Emerging Role of TXNIP in Ischemic and Cardiovascular Diseases; A Novel Marker and Therapeutic Target

Thioredoxin interacting protein (TXNIP) is a metabolism- oxidative- and inflammation-related marker induced in cardiovascular diseases and is believed to represent a possible link between metabolism and cellular redox status. TXNIP is a potential biomarker in cardiovascular and ischemic diseases but also a novel identified target for preventive and curative medicine. The goal of this review is to focus on the novelties concerning TXNIP. After an overview in TXNIP involvement in oxidative stress, inflammation and metabolism, the remainder of this review presents the clues used to define TXNIP as a new marker at the genetic, blood, or ischemic site level in the context of cardiovascular and ischemic diseases.

NLRP3 inflammasome in endothelial dysfunction

Inflammasomes are a class of cytosolic protein complexes. They act as cytosolic innate immune signal receptors to sense pathogens and initiate inflammatory responses under physiological and pathological conditions. The NLR-family pyrin domain-containing protein 3 (NLRP3) inflammasome is the most characteristic multimeric protein complex. Its activation triggers the cleavage of pro-interleukin (IL)-1β and pro-IL-18, which are mediated by caspase-1, and secretes mature forms of these mediators from cells to promote the further inflammatory process and oxidative stress. Simultaneously, cells undergo pro-inflammatory programmed cell death, termed pyroptosis. The danger signals for activating NLRP3 inflammasome are very extensive, especially reactive oxygen species (ROS), which act as an intermediate trigger to activate NLRP3 inflammasome, exacerbating subsequent inflammatory cascades and cell damage. Vascular endothelium at the site of inflammation is actively involved in the regulation of inflammation progression with important implications for cardiovascular homeostasis as a dynamically adaptable interface. Endothelial dysfunction is a hallmark and predictor for cardiovascular ailments or adverse cardiovascular events, such as coronary artery disease, diabetes mellitus, hypertension, and hypercholesterolemia. The loss of proper endothelial function may lead to tissue swelling, chronic inflammation, and the formation of thrombi. As such, elimination of endothelial cell inflammation or activation is of clinical relevance. In this review, we provided a comprehensive perspective on the pivotal role of NLRP3 inflammasome activation in aggravating oxidative stress and endothelial dysfunction and the possible underlying mechanisms. Furthermore, we highlighted the contribution of noncoding RNAs to NLRP3 inflammasome activation-associated endothelial dysfunction, and outlined potential clinical drugs targeting NLRP3 inflammasome involved in endothelial dysfunction. Collectively, this summary provides recent developments and perspectives on how NLRP3 inflammasome interferes with endothelial dysfunction and the potential research value of NLRP3 inflammasome as a potential mediator of endothelial dysfunction.

Sirtuins family as a target in endothelial cell dysfunction: implications for vascular ageing

The vascular endothelium is a protective barrier between the bloodstream and the vasculature that may be disrupted by different factors such as the presence of diseased states. Diseases like diabetes and obesity pose a great risk toward endothelial cell inflammation and oxidative stress, leading to endothelial cell dysfunction and thereby cardiovascular complications such as atherosclerosis. Sirtuins are NAD⁺-dependent histone deacetylases that are implicated in the pathophysiology of cardiovascular diseases, and they have been identified to be important regulators of endothelial cell function. A handful of recent studies suggest that disbalance in the regulation of endothelial sirtuins, mainly sirtuin 1 (SIRT1), contributes to endothelial cell dysfunction. Herein, we summarize how SIRT1 and other sirtuins may contribute to endothelial cell function and how presence of diseased conditions may alter their expressions to cause endothelial dysfunction. Moreover, we discuss how the beneficial effects of exercise on the endothelium are dependent on SIRT1. These mainly include regulation of signaling pathways related to endothelial nitric oxide synthase phosphorylation and nitric oxide production, mitochondrial biogenesis and mitochondria-mediated apoptotic pathways, oxidative stress and inflammatory pathways. Sirtuins as modulators of the adverse conditions in the endothelium hold a promising therapeutic potential for health conditions related to endothelial dysfunction and vascular ageing.