Hyperbaric oxygen therapy as a new treatment approach for Alzheimer's disease

Hyperbaric Oxygen Therapy as an Alternative Therapeutic Option for Radiation-Induced Necrosis Following Radiotherapy for Intracranial Pathologies

BACKGROUND

Radiotherapy (RT) is a feasible adjuvant therapeutic option for managing intracranial pathologies. One of the late complications of RT that frequently develops within months following RT is radiation necrosis (RN). Corticosteroids are the first-line therapeutic option for RNs; however, in case of unfavorable outcomes or intolerability, several other options, including bevacizumab, laser interstitial thermal therapy, surgery, and hyperbaric oxygen therapy (HBOT). Our goal was to investigate the feasibility and efficacy of the application of HBOT in RNs following RT and help physicians make decisions based on the latest data in the literature.

METHODS

We provide a comprehensive review of the literature on the current issues of utilization of HBOT in RNs.

RESULTS

We included 11 studies with a total of 46 patients who underwent HBOT. Most of the cases were diagnosed with brain tumors or arteriovenous malformations. Improvement was achieved in most of the cases.

DISCUSSION

HBOT is a noninvasive therapeutic intervention that can play a role in adjuvant therapy concurrent with RT and chemotherapy and treating RNs. HBOT resolves the RN through 3 mechanisms, including angiogenesis, anti-inflammatory modulation, and cellular repair. Previous studies demonstrated that HBOT is a feasible and well-tolerated therapeutic option that has shown promising results in improving clinical and radiological outcomes in intracranial RNs. Complications of HBOT are usually mild and reversible.

CONCLUSIONS

HBOT is a feasible and effective therapeutic option in steroid-refractory RNs and is associated with favorable outcomes and a low rate of side effects.

The role of oxidative stress and neuroinflammatory mediators in the pathogenesis of high-altitude cerebral edema in rats

High-altitude environments present extreme conditions characterized by low barometric pressure and oxygen deficiency, which can disrupt brain functioning and cause edema formation. The objective of the present study is to investigate several biomolecule expressions and their role in the development of High Altitude Cerebral Edema in a rat model. Specifically, the study focuses on analyzing the changes in total arginase, nitric oxide, and lipid peroxidation (MDA) levels in the brain following acute hypobaric hypoxic exposure (7620 m, SO2=8.1 %, for 24 h) along with the histopathological assessment. The histological examination revealed increased TNF-α activity, and an elevated number of mast cells in the brain, mainly in the hippocampus and cerebral cortex. The research findings demonstrated that acute hypobaric hypoxic causes increased levels of apoptotic cells, shrinkage, and swelling of neurons, accompanied by the formation of protein aggregation in the brain parenchyma. Additionally, the level of nitric oxide and MDA was found to have increased (p<0.0001), however, the level of arginase decreased indicating active lipid peroxidation and redox imbalance in the brain. This study provides insights into the pathogenesis of HACE by evaluating some biomolecules that play a pivotal role in the inflammatory response and the redox landscape in the brain. The findings could have significant implications for understanding the neuronal dysfunction and the pathological mechanisms underlying HACE development.

Expression and metabolism profiles of CVT associated with inflammatory responses and oxygen carrier ability in the brain

AIM

As the main type of stroke, the incidence of cerebral venous thrombosis (CVT) has been rising. However, the comprehensive mechanisms behind it remain unclear. Thus, the multi-omics study is required to investigate the mechanism after CVT and elucidate the characteristic pathology of venous stroke and arterial stroke.

METHODS

Adult rats were subjected to CVT and MCAO models. Whole-transcriptome sequencing (RNA-seq) and untargeted metabolomics analysis were performed to construct the transcriptome and metabolism profiles of rat brains after CVT and also MCAO. The difference analysis, functional annotation, and enrichment analysis were also performed.

RESULTS

Through RNA-seq analysis, differentially expressed genes (DEGs) were screened. 174 CVT specific genes including Il1a, Ccl9, Cxxl6, Tnfrsf14, etc., were detected. The hemoglobin genes, including both Hba and Hbb, were significantly downregulated after CVT, compared both to the MCAO and Sham groups. Metabolism analysis showed that CVT had higher heterogeneity of metabolism compared to MCAO. Metabolites including N-stearoyltyrosine, 5-methoxy-3-indoleaceate, Afegostat, pipecolic acid, etc. were specially regulated in CVT. Through the immune infiltration analysis, it was found that CVT had a higher immune response, with the abundance of certain types of immune cells increased, especially T helper cells. It was important to find the prevalence of the activation of inflammatory chemokine, cytokine, NOD-like pathway, and neutrophil extracellular trap.

CONCLUSION

We explored and analyzed the gene expression and metabolomic characteristics of CVT, revealed the specific inflammatory reaction mechanism of CVT and found the markers in transcriptome and metabolism levels. It points out the direction for CVT early diagnosis and treatment.

Ischemia as a common trigger for Alzheimer’s disease

Alzheimer’s disease has various potential etiologies, all culminating in the accumulation of beta -amyloid derivatives and significant cognitive decline. Vascular-related pathology is one of the more frequent etiologies, especially in persons older than 65 years, as vascular risk factors are linked to both cerebrovascular disease and the development of AD. The vascular patho-mechanism includes atherosclerosis, large and small vessel arteriosclerosis, cortical and subcortical infarcts, white matter lesions, and microbleeds. These insults cause hypoperfusion, tissue ischemia, chronic inflammation, neuronal death, gliosis, cerebral atrophy, and accumulation of beta-amyloid and phosphorylated tau proteins. In preclinical studies, hyperbaric oxygen therapy has been shown to reverse brain ischemia, and thus alleviate inflammation, reverse the accumulation of beta-amyloid, induce regeneration of axonal white matter, stimulate axonal growth, promote blood–brain barrier integrity, reduce inflammatory reactions, and improve brain performance. In this perspective article we will summarize the patho-mechanisms induced by brain ischemia and their contribution to the development of AD. We will also review the potential role of interventions that aim to reverse brain ischemia, and discuss their relevance for clinical practice.

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.

Hyperbaric Oxygen Treatment: Effects on Mitochondrial Function and Oxidative Stress

Hyperbaric oxygen treatment (HBOT)—the administration of 100% oxygen at atmospheric pressure (ATA) greater than 1 ATA—increases the proportion of dissolved oxygen in the blood five- to twenty-fold. This increase in accessible oxygen places the mitochondrion—the organelle that consumes most of the oxygen that we breathe—at the epicenter of HBOT’s effects. As the mitochondrion is also a major site for the production of reactive oxygen species (ROS), it is possible that HBOT will increase also oxidative stress. Depending on the conditions of the HBO treatment (duration, pressure, umber of treatments), short-term treatments have been shown to have deleterious effects on both mitochondrial activity and production of ROS. Long-term treatment, on the other hand, improves mitochondrial activity and leads to a decrease in ROS levels, partially due to the effects of HBOT, which increases antioxidant defense mechanisms. Many diseases and conditions are characterized by mitochondrial dysfunction and imbalance between ROS and antioxidant scavengers, suggesting potential therapeutic intervention for HBOT. In the present review, we will present current views on the effects of HBOT on mitochondrial function and oxidative stress, the interplay between them and the implications for several diseases.

Hyperbaric oxygen therapy induces transcriptome changes in elderly: a prospective trial

Introduction: Aging is characterized by the progressive loss of physiological capacity. Changes in gene expression can alter activity in defined age-related molecular pathways leading to cellular aging and increased aging disease susceptibility. The aim of the current study was to evaluate whether hyperbaric oxygen therapy (HBOT) affects gene expression in normal, non-pathological, aging adults.

Methods: Thirty-five healthy independently living adults, aged 64 and older, were enrolled to receive 60 daily HBOT exposures. Whole blood samples were collected at baseline, at the 30th and 60th HBOT session, and 1–2 weeks following the last session. Differential gene expression analysis was performed.

Results: Following 60 sessions of HBOT, 1342 genes and 570 genes were differently up- and downregulated (1912 total), respectively (p < 0.01 FDR), compared to baseline. Out of which, five genes were downregulated with a >1.5-fold change: ABCA13 (FC = −2.28), DNAJ6 (FC = −2.16), HBG2 (FC = −1.56), PDXDC1 (FC = −1.53), RANBP17 (FC = −1.75). Two weeks post-HBOT, ABCA13 expression was significantly downregulated with a >1.5fold change (FC = −1.54, p = 0.008).

In conclusion, for the first time in humans, the study provides direct evidence of HBOT is associated with transcriptome changes in whole-blood samples. Our results demonstrate significant changes in gene expression of normal aging population.

Hyperbaric Oxygen Treatment-From Mechanisms to Cognitive Improvement

Hyperbaric oxygen treatment (HBOT)—the medical use of oxygen at environmental pressure greater than one atmosphere absolute—is a very effective therapy for several approved clinical situations, such as carbon monoxide intoxication, incurable diabetes or radiation-injury wounds, and smoke inhalation. In recent years, it has also been used to improve cognition, neuro-wellness, and quality of life following brain trauma and stroke. This opens new avenues for the elderly, including the treatment of neurological and neurodegenerative diseases and improvement of cognition and brain metabolism in cases of mild cognitive impairment. Alongside its integration into clinics, basic research studies have elucidated HBOT’s mechanisms of action and its effects on cellular processes, transcription factors, mitochondrial function, oxidative stress, and inflammation. Therefore, HBOT is becoming a major player in 21st century research and clinical treatments. The following review will discuss the basic mechanisms of HBOT, and its effects on cellular processes, cognition, and brain disorders.

Integrative Role of Hyperbaric Oxygen Therapy on Healthspan, Age-Related Vascular Cognitive Impairment, and Dementia

Growing life expectancy will contribute to the on-going shift towards a world population increasingly comprised of elderly individuals. This demographic shift is associated with a rising prevalence of age-related diseases, among all age-related pathologies it has become crucial to understand the age-associated cognitive changes that remain a major risk factor for the development of vascular cognitive impairment and dementia (VCID). Furthermore, age-related Alzheimer's disease and other neurogenerative diseases with vascular etiology are the most prominent contributing factors for the loss of cognitive function observed in aging. Hyperbaric Oxygen Therapy (HBOT) achieves physiologic effects by increasing oxygen tension (PO2), raising oxygen tissue levels, decreasing intracranial pressure and relieving cerebral edema. Many of the beneficial effects of HBOT exert their protective effects at the level of the microcirculation. Furthermore, the microcirculation's exquisite pervasive presence across every tissue in the body, renders it uniquely able to influence the local environment of most tissues and organs, including the brain. As such, treatments aimed at restoring aging-induced functional and structural alterations of the cerebral microcirculation may potentially contribute to the amelioration of a range of age-related pathologies including vascular cognitive impairment, Alzheimer's disease, and vascular dementias. Despite the presented evidence, the efficacy and safety of HBOT for the treatment of age-related vascular cognitive impairment and dementia remains understudied. The present review aims to examine the existing evidence indicative of a potential therapeutic role for HBOT-induced hyperoxia against age-related cerebromicrovascular pathologies contributing to cognitive impairment, dementia and decreased healthspan in the elderly.

Hyperoxygenation Treatment Reduces Beta-amyloid Deposition via MeCP2-dependent Upregulation of MMP-2 and MMP-9 in the Hippocampus of Tg-APP/PS1 Mice

Recently we reported that hyperoxygenation treatment reduces amyloid-beta accumulation and rescues cognitive impairment in the Tg-APP/PS1 mouse model of Alzheimer’s disease. In the present study, we continue to investigate the mechanism by which hyperoxygenation reduces amyloid-beta deposition in the brain. Hyperoxygenation treatment induces upregulation of matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue plasminogen activator (tPA), the endopeptidases that can degrade amyloid-beta, in the hippocampus of Tg-APP/PS1 mice. The promoter regions of the three proteinase genes all contain potential binding sites for MeCP2 and Pea3, which are upregulated in the hippocampus after hyperoxygenation. Hyperoxygenation treatment in HT22 neuronal cells increases MeCP2 but not Pea3 expression. In HT22 cells, siRNA-mediated knockdown of Mecp2 decreases Mmp-9 expression and to a lesser extent, Mmp-2 and tPA expression. In mice, siRNA-mediated Mecp2 knockdown in the hippocampus reduces Mmp-9 expression, but not significantly Mmp-2 and tPA expression. The ChIP assay indicates that hyperoxygenation treatment in Tg-APP/PS1 mice increases MeCP2 binding to the promoter regions of Mmp-2, Mmp-9 and tPA genes in the hippocampus. Together, these results suggest that hyperoxygenation increases the expression of MMP-2, MMP-9, and tPA, of which MMP-9 is upregulated via MeCP2 in neuronal cells, and MMP-2 and tPA are upregulated through MeCP2 and other nuclear factors.

Huperzine A combined with hyperbaric oxygen on the effect on cognitive function and serum hypoxia-inducible factor-1α Level in elderly patients with vascular dementia

OBJECTIVE

To explore the clinical effect of huperzine A combined with hyperbaric oxygen on cognitive function and serum hypoxia-inducible factor-1α (HIF-1α) level in elderly patients with vascular dementia (VD).

METHODS

120 elderly VD patients admitted to our hospital from February 2018 to March 2020 were selected and divided into two groups according to the treatment method (n = 60 each). They were administered for huperzine A and huperzine A combined with hyperbaric oxygen, respectively. The comparison of disease control rate (DCR), mini-mental state examination (MMSE) score, revised hasegawa's dementia scale (HDS-R) score and serum index were conducted.

RESULTS

At 2 and 4 weeks after treatment, the HDS-R and MMSE scores were reported to be higher in the observation group than those in the control group (P < 0.05), and the vascular endothelial growth factor (VEGF), anti-apoptotic factor (Livin), and HIF-1α showed a higher level of improvement as compared with the control group (P < 0.05). Moreover, the DCR in the observation group was much higher than that in the control group (P < 0.05).

CONCLUSION

Huperzine A combined with hyperbaric oxygen is remarkably effective in the treatment of elderly VD patients. It can improve the serum HIF-1α level and speed up the recovery of cognitive function.

Inflammatory seborrheic keratosis resolution after hyperbaric oxygen therapy: Case presentation and pathophysiology review

Seborrheic keratosis (SK) is a common epidermal tumor, consisting of a benign proliferation of immature keratinocytes. The natural history of SK is a slow progression over time and complete remission is not expected. The article presents the first case of a complete resolution of a large (2.5 cm diameter) SK lesion after hyperbaric oxygen therapy (HBOT). In addition to the case presentation, the pathophysiology of SK and the potential beneficial physiological effects of HBOT are reviewed and discussed.

Wernicke's encephalopathy in Crohn's disease and ulcerative colitis

Crohn's disease (CD) and ulcerative colitis (UC) are chronic and debilitating inflammatory conditions of the gastrointestinal tract. Thiamine can deplete rapidly in CD and UC, which can lead to Wernicke's encephalopathy (WE), is an acute neurologic disorder. Our objective was to systematically review the presentation of WE in CD and UC. We conducted our search from inception using the MeSH terms "Crohn's disease," "ulcerative colitis," and "Wernicke's encephalopathy." Our search yielded 28 case studies reporting on 31 cases. CD was diagnosed in 21 cases, and UC in 10. The first signs of WE were nausea and vomiting (13 cases), double vision (10), blurred vision (10), and hearing loss (4). In 12 cases, partial or complete bowel resection was one of the etiologies of thiamine depletion. In nine cases, thiamine was not supplemented intramuscularly or intravenously while parenteral nutrition or glucose was given to the patient. In 10 cases, detailed descriptions of thiamine treatment were given. Thiamine treatment at suboptimal levels (7 of 10 cases) turned out to lead to residual cognitive deficits in three cases. In three cases with optimal treatment (1500 mg/d intravenously), complete remission of WE symptoms was achieved. Rapid treatment with high doses (500 mg, 3 times/d) of thiamine saves lives, and treats WE in its core symptomatology.

Effects of Dissolved Gases on the Amyloid Fibril Morphology

The onset or progression of numerous neurodegenerative diseases occurs due to aggregation of proteins that ultimately form fibrils. The assembly and morphology of fibrils are susceptible to environmental factors. In this work, we used atomic force microscopy (AFM) to investigate the effects of dissolved nitrogen and oxygen molecules on the morphology of fibrils formed by a hydrophobic amyloid peptide implicated in amyotrophic lateral sclerosis, 15 repeats of glycine-alanine, on a highly oriented pyrolytic graphite substrate. We started with preformed fibril solutions that were then diluted with buffers of different gas conditions, resulting in the aggregation of the fibrils into different morphologies that were revealed by AFM after adsorption on the substrate. Straight fibrils were observed in both degassed and ambient buffers, but a stronger lateral association was seen in degassed buffers. Smaller and softer fibrils were observed in O₂-supersaturated buffers, and plaque-like fibril aggregates of considerably large size were evident in N₂-supersaturated buffers. In overnight incubation experiments, we observed changes in both the morphology and height of the fibril aggregates, and their evolution varied with different gas conditions. These findings indicate that the gas type and concentration affect the aggregation of amyloid fibrils and may facilitate the development of biomaterial applications and treatments for amyloid-related diseases.

Hyperbaric oxygen therapy increases telomere length and decreases immunosenescence in isolated blood cells: a prospective trial

INTRODUCTION

Aging is characterized by the progressive loss of physiological capacity. At the cellular level, two key hallmarks of the aging process include telomere length (TL) shortening and cellular senescence. Repeated intermittent hyperoxic exposures, using certain hyperbaric oxygen therapy (HBOT) protocols, can induce regenerative effects which normally occur during hypoxia. The aim of the current study was to evaluate whether HBOT affects TL and senescent cell concentrations in a normal, non-pathological, aging adult population.

METHODS

Thirty-five healthy independently living adults, aged 64 and older, were enrolled to receive 60 daily HBOT exposures. Whole blood samples were collected at baseline, at the 30^th and 60^th session, and 1-2 weeks following the last HBOT session. Peripheral blood mononuclear cells (PBMCs) telomeres length and senescence were assessed.

RESULTS

Telomeres length of T helper, T cytotoxic, natural killer and B cells increased significantly by over 20% following HBOT. The most significant change was noticed in B cells which increased at the 30^th session, 60^th session and post HBOT by 25.68%±40.42 (p=0.007), 29.39%±23.39 (p=0.0001) and 37.63%±52.73 (p=0.007), respectively. There was a significant decrease in the number of senescent T helpers by -37.30%±33.04 post-HBOT (P<0.0001). T-cytotoxic senescent cell percentages decreased significantly by -10.96%±12.59 (p=0.0004) post-HBOT. In conclusion, the study indicates that HBOT may induce significant senolytic effects including significantly increasing telomere length and clearance of senescent cells in the aging populations.

Breaking the Glass Ceiling

Over the past century, the life expectancy in industrialized countries has rapidly risen by over 30 years due to improvements in standards of medical care, sanitation, and lifestyle. Estimation of life expectancy has traditionally been viewed through a lens of epidemiology and public health. However, this data, while considered the "gold standard" of measuring healthy life expectancy, may soon find itself redundant in the face of advancing medical technology. Even as average life expectancy has increased, there has not been an equivalent increase in healthy life expectancy, or "healthspan"; furthermore, there is a current trend of stagnation in life expectancy, as the supposed increases are estimated to be drastically slowing down, in part due to exhaustion of our current ability to extend the human lifespan. In this viewpoint, we will examine the developing fields of medicine and life sciences which will reshape our current approach to life expectancy prediction.