Effect of Nrf2 signaling pathway on the improvement of intestinal epithelial barrier dysfunction by hyperbaric oxygen treatment after spinal cord injury

TRAUMA AND THE ENTEROCYTE: DISTURBANCE OF COMMUNICATION AND DELINEATION

ABSTRACT

The enterocyte as major building stone of the intestinal barrier plays a central role in maintaining cellular homeostasis and mediating host-environment interactions. Trauma, whether direct or remote, disrupts enterocyte function through complex mechanisms including impaired oxygen delivery, disturbed intercellular communication, and compromised nutrient uptake and metabolite clearance. These changes may lead to barrier dysfunction and altered repair mechanisms, facilitating systemic inflammation and remote organ injury. The failure of communication pathways-both within enterocytes and across epithelial networks-undermines coordinated responses to injury. Understanding these multifaceted perturbations reveals the enterocyte not merely as a passive victim but as an active participant in trauma-induced pathology. Emerging therapeutic strategies focus on enhancing mucosal repair via sealing agents, promoting epithelial proliferation, and restoring metabolic and signaling homeostasis. This review delineates the dynamic response of the enterocyte to trauma, highlighting opportunities for targeted interventions aimed at restoring intestinal integrity and function.

Limosilactobacillus reuteri DSM17938 Attenuates Neuroinflammatory Responses After Spinal Cord Injury by Modulating Tryptophan Metabolism

Spinal cord injury (SCI) disrupts gut flora and exacerbates neuroinflammation. Evidence supports the important role of the intestinal microbiota in SCI. This study evaluated the neuroprotective effect of Limosilactobacillus reuteri (L. reuteri) DSM 17938 on SCI and its potential anti-inflammatory mechanism. The intestinal microbiota was disorganised following SCI, with a significant decrease in the abundance of probiotic bacteria such as L. reuteri. L. reuteri DSM17938 treatment improved the spinal cord pathology and enhanced locomotor functional recovery in SCI-model rats. Moreover, it modulated tryptophan metabolism by promoting indole-3-carboxaldehyde production. In addition, L. reuteri DSM17938 inhibits polarization of M1 microglia and reduces the production of IL-6, IL-1 β, and TNF-α in spinal cord injury to alleviate neuroinflammation. It also activates aryl hydrocarbon receptor (AhR) signalling via upregulating AhR and CYP1A1 expression, promoting tight junction protein synthesis. In summary, L. reuteri DSM17938 promotes SCI recovery by modulating tryptophan metabolism to activate AhR signalling and intestinal barrier repair to attenuate spinal cord M1 microglial activation and neuroinflammation, suggesting a strategy for clinical adjuvant SCI treatment.

Mechanism of effect and therapeutic potential of NLRP3 inflammasome in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury that can trigger various neuropathological conditions, resulting in neuronal damage and release of various pro-inflammatory mediators, leading to neurological dysfunction. Currently, surgical decompression, drugs and rehabilitation are primarily used to relieve symptoms and improve endogenous repair mechanisms; however, they cannot directly promote nerve regeneration and functional recovery. SCI can be divided into primary and secondary injuries. Secondary injury is key to determining the severity of injury, whereas inflammation and cell death are important pathological mechanisms in the process of secondary SCI. The activation of the inflammasome complex is thought to be a necessary step in neuro-inflammation and a key trigger for neuronal death. The NLRP3 inflammasome is a cytoplasmic multiprotein complex that is considered an important factor in the development of SCI. Once the NLRP3 inflammasome is activated after SCI, NLRP3 nucleates the assembly of an inflammasome, leading to caspase 1-mediated proteolytic activation of the interleukin-1β (IL-1β) family of cytokines, and induces an inflammatory, pyroptotic cell death. Inhibition of inflammasomes can effectively inhibit inflammation and cell death in the body and promote the recovery of nerve function after SCI. Therefore, inhibition of NLRP3 inflammasome activation may be a promising approach for the treatment of SCI. In this review, we describe the current understanding of NLRP3 inflammasome activation in SCI pathogenesis and its subsequent impact on SCI and summarize drugs and other potential inhibitors based on NLRP3 inflammasome regulation. The objective of this study was to emphasize the role of the NLRP3 inflammasome in SCI, and provide a new therapeutic strategy and theoretical basis for targeting the NLRP3 inflammasome as a therapy for SCI.

Endothelial Dysfunction and Cardiovascular Disease: Hyperbaric Oxygen Therapy as an Emerging Therapeutic Modality?

Maintaining the physiological function of the vascular endothelium and endothelial glycocalyx is crucial for the prevention of cardiovascular disease, which is one of the leading causes of morbidity and mortality worldwide. Damage to these structures can lead to atherosclerosis, hypertension, and other cardiovascular problems, especially in individuals with risk factors such as diabetes and obesity. Endothelial dysfunction is associated with ischemic disease and has a negative impact on overall cardiovascular health. The aim of this review was to comprehensively summarize the crucial role of the vascular endothelium and glycocalyx in cardiovascular health and associated thrombo-inflammatory conditions. It highlights how endothelial dysfunction, influenced by factors such as diabetes, chronic kidney disease, and obesity, leads to adverse cardiovascular outcomes, including heart failure. Recent evidence suggests that hyperbaric oxygen therapy (HBOT) may offer therapeutic benefits in the treatment of cardiovascular risk factors and disease. This review presents the current evidence on the mechanisms by which HBOT promotes angiogenesis, shows antimicrobial and immunomodulatory effects, enhances antioxidant defenses, and stimulates stem cell activity. The latest findings on important topics will be presented, including the effects of HBOT on endothelial dysfunction, cardiac function, atherosclerosis, plaque stability, and endothelial integrity. In addition, the role of HBOT in alleviating cardiovascular risk factors such as hypertension, aging, obesity, and glucose metabolism regulation is discussed, along with its impact on inflammation in cardiovascular disease and its potential benefit in ischemia-reperfusion injury. While HBOT demonstrates significant therapeutic potential, the review also addresses potential risks associated with excessive oxidative stress and oxygen toxicity. By combining information on the molecular mechanisms of HBOT and its effects on the maintenance of vascular homeostasis, this review provides valuable insights into the development of innovative therapeutic strategies aimed at protecting and restoring endothelial function to prevent and treat cardiovascular diseases.

Epigenetic modifications of inflammation in spinal cord injury

Spinal cord injury (SCI) is a central nervous system injury that leads to neurological dysfunction or paralysis, which seriously affects patients' quality of life and causes a heavy social and economic burden. The pathological mechanism of SCI has not been fully revealed, resulting in unsatisfactory clinical treatment. Therefore, more research is urgently needed to reveal its precise pathological mechanism. Numerous studies have shown that inflammation is closely related to various pathological processes in SCI. Inflammatory response is an important pathological process leading to secondary injury, and sustained inflammatory response can exacerbate the injury and hinder the recovery of neurological function after injury. Epigenetic modification is considered to be an important regulatory mechanism in the pathological process of many diseases. Epigenetic modification mainly affects the function and characteristics of genes through the reversibility of mechanisms such as DNA methylation, histone modification, and regulation of non-coding RNA, thus having a significant impact on the pathological process of diseases and the survival state of the body. Recently, the role of epigenetic modification in the inflammatory response of SCI has gradually entered the field of view of researchers, and epigenetic modification may be a potential means to treat SCI. In this paper, we review the effects and mechanisms of different types of epigenetic modifications (including histone modifications, DNA methylation, and non-coding RNAs) on post-SCI inflammation and their potential therapeutic effects on inflammation to improve our understanding of the secondary SCI stage. This review aims to help identify new markers, signaling pathways and targeted drugs, and provide theoretical basis and new strategies for the diagnosis and treatment of SCI.

Regional Heterogeneity in Intestinal Epithelial Barrier Permeability and Mesenteric Perfusion After Thoracic Spinal Cord Injury

BACKGROUND

Spinal cord injury (SCI) disrupts intestinal barrier function, thereby increasing antigen permeation and leading to poor outcomes. Despite the intestinal tract's anatomic and physiologic heterogeneity, studies following SCI have not comprehensively addressed intestinal pathophysiology with regional specificity.

AIMS AND METHODS

We used an experimental model of high thoracic SCI to investigate (1) regional mucosal oxidative stress using dihydroethidium labeling; (2) regional paracellular permeability to small- and large-molecular probes via Ussing chamber; (3) regional intestinal tight junction (TJ) protein expression; and (4) hindgut perfusion via the caudal mesenteric artery.

RESULTS

Dihydroethidium staining was significantly elevated within duodenal mucosa at 3-day post-SCI. Molar flux of [14C]-urea was significantly elevated in duodenum and proximal colon at 3-day post-SCI, while molar flux of [3H]-inulin was significantly elevated only in duodenum at 3-day post-SCI. Barrier permeability was mirrored by a significant increase in the expression of pore-forming TJ protein claudin-2 in duodenum and proximal colon at 3-day post-SCI. Claudin-2 expression remained significantly elevated in proximal colon at 3-week post-SCI. Expression of the barrier-forming TJ protein occludin was significantly reduced in duodenum at 3-day post-SCI. Caudal mesenteric artery flow was unchanged by SCI at 3 days or 3 weeks despite significant reductions in mean arterial pressure.

CONCLUSION

These data show that T3-SCI provokes elevated mucosal oxidative stress, altered expression of TJ proteins, and elevated intestinal barrier permeability in the proximal intestine. In contrast, mucosal oxidative stress and intestinal barrier permeability were unchanged in the hindgut after SCI. This regional heterogeneity may result from differential sensitivity to reduced mesenteric perfusion, though further studies are required to establish a causal link. Understanding regional differences in intestinal pathophysiology is essential for developing effective treatments and standards of care for individuals with SCI.

Hyperbaric oxygen therapy alleviates intestinal dysfunction following traumatic brain injury via m6A regulation

Hyperbaric oxygen (HBO) therapy can attenuate neurological impairment after traumatic brain injury (TBI) and alleviate intestinal dysfunction. However, the role and mechanism of HBO therapy in intestinal dysfunction following TBI remain unclear. Herein, by establishing a mouse model of controlled cortical impact (CCI), we found that HBO therapy reduced histopathological lesions and decreased the levels of inflammatory and oedema proteins in the intestinal tissues of mice 10 days after TBI. We also showed that HBO therapy improved microbiome abundance and probiotic (particularly g_Bifidobacterium) colonisation in mice post-CCI. Then, we identified that the m6A level imcreased notably in injured cortical tissue of CCI+HBO group compared with the CCI group following CCI. Thus, our results suggested that HBO therapy could alleviate TBI-induced intestinal dysfunction and m6A might participate in this regulation process, which provides new insights for exploring the specific mechanism and targets of HBO in the treatment of intestinal dysfunction after TBI, thereby improving the therapeutic effect of HBO.

The new insights of hyperbaric oxygen therapy: focus on inflammatory bowel disease

Inflammatory bowel diseases (IBD), with an increasing incidence, pose a significant health burden. Although there have been significant advances in the treatment of IBD, more progress is still needed. Hyperbaric oxygen therapy (HBOT) has been shown to treat a host of conditions such as carbon monoxide poisoning, decompression sickness, and gas gangrene. In the last few years, there has been an increase in research into the use of HBOT as an adjunct to conventional treatment for IBD. Related research has shown that HBOT may exert its therapeutic effects by decreasing oxidative stress, inhibiting mucosal inflammation, promoting ulcer healing, influencing gut microbes, and reducing the incidence of IBD complications. This paper aims to provide a comprehensive review of experimental and clinical trials exploring HBOT as a supplement to IBD treatment strategies.

Hyperbaric Oxygen Therapy Inhibits Neuronal Ferroptosis After Spinal Cord Injury in Mice

STUDY DESIGN

Basic science study investigating the potential molecular mechanisms of hyperbaric oxygen (HBO) therapy in mice with spinal cord injury (SCI).

OBJECTIVE

We aimed to explore the intrinsic mechanisms of HBO for SCI through the lens of ferroptosis in the subacute phase.

SUMMARY OF BACKGROUND DATA

HBO has been observed to facilitate the restoration of neurological function subsequent to SCI. Ferroptosis is a distinct cellular death mechanism that can be distinguished from apoptosis, necrosis, and autophagy. However, the precise relationship between these two phenomena remains poorly understood.

METHODS

We established an SCI model and employed a range of techniques, including behavioral assessments, electron microscopy, immunofluorescence, RT-qPCR, Western blotting (WB), Glutathione (GSH) measurement, and iron assay, to investigate various aspects of HBO therapy on SCI in mice. These included analyzing mitochondrial morphology, neuronal count, GSH levels, iron levels, and the expression of genes (Acyl-CoA synthetase family member-2, Iron-responsive element-binding protein-2) and proteins (Glutathione peroxidase 4; system Xc-light chain) associated with ferroptosis. The study included three groups: Sham-operated, SCI, and HBO. Group comparisons were performed using one-way analysis of variance and one-way repeated measures analysis of variance, followed by Tukey's post hoc test. Statistical significance was set at a P < 0.05.

RESULTS

Our findings revealed that HBO therapy significantly enhanced the recovery of lower limb motor function in mice following SCI in the subacute phase. This was accompanied by upregulated expression of GPX4 and system Xc-light chain proteins, elevated GSH levels, increased number of NeuN+ cells, decreased expression of the iron-responsive element-binding protein-2 gene, and reduced iron concentration.

CONCLUSIONS

Our research suggests that HBO therapy has the potential to be an effective treatment for SCI in the subacute phase by mitigating ferroptosis.

Nrf2 Activation: Involvement in Central Nervous System Traumatic Injuries. A Promising Therapeutic Target of Natural Compounds

Central nervous system (CNS) trauma, such as traumatic brain injury (TBI) and spinal cord injury (SCI), represents an increasingly important health burden in view of the preventability of most injuries and the complex and expensive medical care that they necessitate. These injuries are characterized by different signs of neurodegeneration, such as oxidative stress, mitochondrial dysfunction, and neuronal apoptosis. Cumulative evidence suggests that the transcriptional factor nuclear factor erythroid 2-related factor 2 (Nrf2) plays a crucial defensive role in regulating the antioxidant response. It has been demonstrated that several natural compounds are able to activate Nrf2, mediating its antioxidant response. Some of these compounds have been tested in experimental models of SCI and TBI, showing different neuroprotective properties. In this review, an overview of the preclinical studies that highlight the positive effects of natural bioactive compounds in SCI and TBI experimental models through the activation of the Nrf2 pathway has been provided. Interestingly, several natural compounds can activate Nrf2 through multiple pathways, inducing a strong antioxidant response against CNS trauma. Therefore, some of these compounds could represent promising therapeutic strategies for these pathological conditions.

Intestinal microbiota and melatonin in the treatment of secondary injury and complications after spinal cord injury

Spinal cord injury (SCI) is a central nervous system (CNS) disease that can cause sensory and motor impairment below the level of injury. Currently, the treatment scheme for SCI mainly focuses on secondary injury and complications. Recent studies have shown that SCI leads to an imbalance of intestinal microbiota and the imbalance is also associated with complications after SCI, possibly through the microbial-brain-gut axis. Melatonin is secreted in many parts of the body including pineal gland and gut, effectively protecting the spinal cord from secondary damage. The secretion of melatonin is affected by circadian rhythms, known as the dark light cycle, and SCI would also cause dysregulation of melatonin secretion. In addition, melatonin is closely related to the intestinal microbiota, which protects the barrier function of the gut through its antioxidant and anti-inflammatory effects, and increases the abundance of intestinal microbiota by influencing the metabolism of the intestinal microbiota. Furthermore, the intestinal microbiota can influence melatonin formation by regulating tryptophan and serotonin metabolism. This paper summarizes and reviews the knowledge on the relationship among intestinal microbiota, melatonin, and SCI in recent years, to provide new theories and ideas for clinical research related to SCI treatment.

Melatonin Attenuates Spinal Cord Injury in Mice by Activating the Nrf2/ARE Signaling Pathway to Inhibit the NLRP3 Inflammasome

Background: Spinal cord injury (SCI) is a central nervous system (CNS) trauma involving inflammation and oxidative stress, which play important roles in this trauma’s pathogenesis. Therefore, controlling inflammation is an effective strategy for SCI treatment. As a hormone, melatonin is capable of producing antioxidation and anti-inflammation effects. In the meantime, it also causes a neuroprotective effect in various neurological diseases. Nrf2/ARE/NLRP3 is a well-known pathway in anti-inflammation and antioxidation, and Nrf2 can be positively regulated by melatonin. However, how melatonin regulates inflammation during SCI is poorly explored. Therefore, it was investigated in this study whether melatonin can inhibit the NLRP3 inflammasome through the Nrf2/ARE signaling pathway in a mouse SCI model. Methods: A model of SCI was established in C57BL/6 mice and PC12 cells. The motor function of mice was detected by performing an open field test, and Nissl staining and terminal deoxynucleotidyl transferase dUTP nick end labeling were carried out to evaluate the survival of neurons. Mitochondrial dysfunction was detected by transmission electron microscopy (TEM) and by assessing the mitochondrial membrane potential. In addition, the expression of NLRP3 inflammasome and oxidative-stress-related proteins were detected through Western blot and immunofluorescence double staining. Results: By inhibiting neuroinflammation and reducing neuronal death, melatonin promotes the recovery of neuromotor function. Besides this, melatonin is able to reduce the damage that causes neuronal mitochondrial dysfunction, reduce the level of reactive oxygen species (ROS) and malondialdehyde, and enhance the activity of superoxide dismutase and the production of glutathione peroxidase. Mechanically, melatonin inhibits the activation of NLRP3 inflammasomes and reduces the secretion of pro-inflammatory factors through the Nrf2/ARE signaling. Conclusions: In conclusion, melatonin inhibits the NLRP3 inflammasome through stimulation of the Nrf2/ARE pathway, thereby suppressing neuroinflammation, reducing mitochondrial dysfunction, and improving the recovery of nerve function after SCI.

Hyperbaric oxygen therapy for healthy aging: From mechanisms to therapeutics

Hyperbaric oxygen therapy (HBOT), a technique through which 100% oxygen is provided at a pressure higher than 1 atm absolute (ATA), has become a well-established treatment modality for multiple conditions. The noninvasive nature, favorable safety profile, and common clinical application of HBOT make it a competitive candidate for several new indications, one of them being aging and age-related diseases. In fact, despite the conventional wisdom that excessive oxygen accelerates aging, appropriate HBOT protocols without exceeding the toxicity threshold have shown great promise in therapies against aging. For one thing, an extensive body of basic research has expanded our mechanistic understanding of HBOT. Interestingly, the therapeutic targets of HBOT overlap considerably with those of aging and age-related diseases. For another, pre-clinical and small-scale clinical investigations have provided validated information on the efficacy of HBOT against aging from various aspects. However, a generally applicable protocol for HBOT to be utilized in therapies against aging needs to be defined as a subsequent step. It is high time to look back and summarize the recent advances concerning biological mechanisms and therapeutic implications of HBOT in promoting healthy aging and shed light on prospective directions. Here we provide the first comprehensive overview of HBOT in the field of aging and geriatric research, which allows the scientific community to be aware of the emerging tendency and move beyond conventional wisdom to scientific findings of translational value.

Recent Advances in the Role of Nuclear Factor Erythroid-2-Related Factor 2 in Spinal Cord Injury: Regulatory Mechanisms and Therapeutic Options

Nuclear factor erythroid-2-related factor 2 (Nrf2) is a pleiotropic transcription factor, and it has been documented that it can induce defense mechanisms both oxidative stress and inflammatory injury. At present, more and more evidences show that the Nrf2 signaling pathway is a key pharmacological target for the treatment of spinal cord injury (SCI), and activating the Nrf2 signaling pathway can effectively treat the inflammatory injury and oxidative stress after SCI. This article firstly introduces the biological studies of the Nrf2 pathway. Meanwhile, it is more powerful to explain that activating the Nrf2 signaling pathway can effectively treat SCI by deeply exploring the relationship between Nrf2 and oxidative stress, inflammatory injury, and SCI. In addition, several potential drugs for the treatment of SCI by promoting Nrf2 activation and Nrf2-dependent gene expression are reviewed. And some other treatment strategies of SCI by modulating the Nrf2 pathway are also summarized. It will provide new ideas and directions for the treatment of SCI.

Survey of Molecular Mechanisms of Hyperbaric Oxygen in Tissue Repair

For more than six decades, hyperbaric oxygen (HBO) has been used for a variety of indications involving tissue repair. These indications comprise a wide range of diseases ranging from intoxications to ischemia-reperfusion injury, crush syndrome, central nervous injury, radiation-induced tissue damage, burn injury and chronic wounds. In a systematic review, the molecular mechanisms triggered by HBO described within the last two decades were compiled. They cover a wide range of pathways, including transcription, cell-to-cell contacts, structure, adhesion and transmigration, vascular signaling and response to oxidative stress, apoptosis, autophagy and cell death, as well as inflammatory processes. By analyzing 71 predominantly experimental publications, we established an overview of the current concepts regarding the molecular mechanisms underlying the effects of HBO. We considered both the abovementioned pathways and their role in various applications and indications.