Tag: oxidative stress

Innate Immune Activation and Mitochondrial ROS Invoke Persistent Cardiac Conduction System Dysfunction after COVID-19

Abstract:

Background Cardiac risk rises during acute SARS-CoV-2 infection and in long COVID syndrome in humans, but the mechanisms behind COVID-19-linked arrhythmias are unknown. This study explores the acute and long term effects of SARS-CoV-2 on the cardiac conduction system (CCS) in a hamster model of COVID-19.

Methods Radiotelemetry in conscious animals was used to non-invasively record electrocardiograms and subpleural pressures after intranasal SARS-CoV-2 infection. Cardiac cytokines, interferon-stimulated gene expression, and macrophage infiltration of the CCS, were assessed at 4 days and 4 weeks post-infection. A double-stranded RNA mimetic, polyinosinic:polycytidylic acid (PIC), was used in vivo and in vitro to activate viral pattern recognition receptors in the absence of SARS-CoV-2 infection.

Results COVID-19 induced pronounced tachypnea and severe cardiac conduction system (CCS) dysfunction, spanning from bradycardia to persistent atrioventricular block, although no viral protein expression was detected in the heart. Arrhythmias developed rapidly, partially reversed, and then redeveloped after the pulmonary infection was resolved, indicating persistent CCS injury. Increased cardiac cytokines, interferon-stimulated gene expression, and macrophage remodeling in the CCS accompanied the electrophysiological abnormalities. Interestingly, the arrhythmia phenotype was reproduced by cardiac injection of PIC in the absence of virus, indicating that innate immune activation was sufficient to drive the response. PIC also strongly induced cytokine secretion and robust interferon signaling in hearts, human iPSC-derived cardiomyocytes (hiPSC-CMs), and engineered heart tissues, accompanied by alterations in electrical and Ca2+ handling properties. Importantly, the pulmonary and cardiac effects of COVID-19 were blunted by in vivo inhibition of JAK/STAT signaling or by a mitochondrially-targeted antioxidant.

Conclusions The findings indicate that long term dysfunction and immune cell remodeling of the CCS is induced by COVID-19, arising indirectly from oxidative stress and excessive activation of cardiac innate immune responses during infection, with implications for long COVID Syndrome.

Source: Deepthi Ashok, Ting Liu, Joseph Criscione, Meghana Prakash, Byunggik Kim, Julian Chow, Morgan Craney, Kyriakos N. Papanicolaou, Agnieszka Sidor, D. Brian Foster, Andrew Pekosz, Jason Villano, Deok-Ho Kim, Brian O’Rourke. Innate Immune Activation and Mitochondrial ROS Invoke Persistent Cardiac Conduction System Dysfunction after COVID-19. bioRxiv 2024.01.05.574280; doi: https://doi.org/10.1101/2024.01.05.574280 https://www.biorxiv.org/content/10.1101/2024.01.05.574280v1.full (Full text)

Arterial Stiffness and Oxidized LDL Independently Associated With Post-Acute Sequalae of SARS-CoV-2

Abstract:

Objective: COVID-19 survivors can experience lingering symptoms known as post-acute sequelae of SARS-CoV-2 (PASC) that appear in different phenotypes, and its etiology remains elusive. We assessed the relationship of endothelial dysfunction with having COVID and PASC.

Methods: Data was collected from a prospectively enrolled cohort (n=379) of COVID-negative and COVID-positive participants with and without PASC. Primary outcomes, endothelial function (measured by reactive hyperemic index [RHI]), and arterial elasticity (measured by augmentation index standardized at 75 bpm [AI]), were measured using the FDA approved EndoPAT. Patient characteristics, labs, metabolic measures, markers of inflammation, and oxidized LDL (ox-LDL) were collected at each study visit, and PASC symptoms were categorized into 3 non-exclusive phenotypes: cardiopulmonary, neurocognitive, and general. COVID-negative controls were propensity score matched to COVID-negative-infected cases using the greedy nearest neighbor method.

Results: There were 14.3% of participants who were fully recovered COVID positive and 28.5% who were COVID positive with PASC, averaging 8.64 ± 6.26 total number of symptoms. The mean RHI was similar across the cohort and having COVID or PASC was not associated with endothelial function (P=0.33). Age (P<0.0001), female sex (P<0.0001), and CRP P=0.04) were positively associated with arterial stiffness, and COVID positive PASC positive with neurological and/or cardiopulmonary phenotypes had the worst arterial elasticity (highest AI). Values for AI (P=0.002) and ox-LDL (P<0.0001) were independently and positively associated with an increased likelihood of having PASC.

Conclusion: There is evidence of an independent association between PASC, ox-LDL, and arterial stiffness with neurological and/or cardiopulmonary phenotypes having the worst arterial elasticity. Future studies should continue investigating the role of oxidative stress in the pathophysiology of PASC.

Source: Zisis SN, Durieux JC, Mouchati C, Funderburg N, Ailstock K, Chong M, Labbato D, McComsey GA. Arterial Stiffness and Oxidized LDL Independently Associated With Post-Acute Sequalae of SARS-CoV-2. Pathog Immun. 2023 Dec 20;8(2):1-15. doi: 10.20411/pai.v8i2.634. PMID: 38156116; PMCID: PMC10753933. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10753933/ (Full text)

Identification of CD8 T-cell dysfunction associated with symptoms in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and Long COVID and treatment with a nebulized antioxidant/anti-pathogen agent in a retrospective case series

Highlights:

• Both Long COVID and ME/CFS are characterized by dysfunctional CD8 T-cells with severe deficiencies in their abilities to produce IFNγ and TNFα.

• In a small Long COVID and ME/CFS case series, patients’ immune deficiency and health improve during treatment period with a nebulized antioxidant, anti-pathogen and immune-modulatory pharmacological agent.

• This work provides evidence of a useful biomarker, CD8 T-cell dysfunction reminiscent of T cell exhaustion, that may assist diagnosis and have utility for tracking disease outcome during therapy, including response to a potential new treatment.

Abstract:

Background: Patients with post-acute sequelae of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection (PASC, i.e., Long COVID) have a symptom complex highly analogous to many features of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), suggesting they may share some aspects of pathogenesis in these similar disorders. ME/CFS is a complex disease affecting numerous organ systems and biological processes and is often preceded by an infection-like episode. It is postulated that the chronic manifestations of illness may result from an altered host response to infection or inability to resolve inflammation, as is being reported in Long COVID. The immunopathogenesis of both disorders is still poorly understood. Here, we show data that suggest Long COVID and ME/CFS may be due to an aberrant response to an immunological trigger-like infection, resulting in a dysregulated immune system with CD8 T-cell dysfunction reminiscent of some aspects of T-cell clonal exhaustion, a phenomenon associated with oxidative stress. As there is an urgent need for diagnostic tools and treatment strategies for these two related disabling disorders, here, in a retrospective case series, we have also identified a potential nebulized antioxidant/anti-pathogen treatment that has evidence of a good safety profile. This nebulized agent is comprised of five ingredients previously reported individually to relieve oxidative stress, attenuate NF-κB signaling, and/or to act directly to inhibit pathogens, including viruses. Administration of this treatment by nebulizer results in rapid access of small doses of well-studied antioxidants and agents with anti-pathogen potential to the lungs; components of this nebulized agent are also likely to be distributed systemically, with potential to enter the central nervous system.

Methods and Findings: We conducted an analysis of CD8 T-cell function and severity of symptoms by self-report questionnaires in ME/CFS, Long COVID and healthy controls. We developed a CD8 T-cell functional assay, assessing CD8 T-cell dysfunction by intracellular cytokine staining (ICS) in a group of ME/CFS (n = 12) and Long COVID patients (n = 8), comparing to healthy controls (HC) with similar age and sex (n = 10). Magnet-enriched fresh CD8 T-cells in both patient groups had a significantly diminished capacity to produce both cytokines, IFNγ or TNFα, after PMA stimulation when compared to HC. The symptom severity questionnaire showed similar symptom profiles for the two disorders. Fortuitously, through a retrospective case series, we were able to examine the ICS and questionnaire data of 4 ME/CFS and 4 Long COVID patients in conjunction with their treatment (3–15 months). In parallel with the treatment pursued electively by participants in this retrospective case series, there was an increase in CD8 T-cell IFNγ and TNFα production and a decrease in overall self-reported symptom severity score by 54%. No serious treatment-associated side effects or laboratory anomalies were noted in these patients.

Conclusions: Here, in this small study, we present two observations that appear potentially fundamental to the pathogenesis and treatment of Long COVID and ME/CFS. The first is that both disorders appear to be characterized by dysfunctional CD8 T-cells with severe deficiencies in their abilities to produce IFNγ and TNFα. The second is that in a small retrospective Long COVID and ME/CFS case series, this immune dysfunction and patient health improved in parallel with treatment with an immunomodulatory, antioxidant pharmacological treatment with anticipated anti-pathogen activity. This work provides evidence of the potential utility of a biomarker, CD8 T-cell dysfunction, and suggests the potential for benefit from a new nebulized antioxidant/anti-pathogen treatment. These immune biomarker data may help build capacity for improved diagnosis and tracking of treatment outcomes during clinical trials for both Long COVID and ME/CFS while providing clues to new treatment avenues that suggest potential efficacy for both conditions.

Source: Gil, A., Hoag, G.E., Salerno, J.P., Hornig, M., Klimas, N., Selin, L.K. Identification of CD8 T-cell dysfunction associated with symptoms in myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) and Long COVID and treatment with a nebulized antioxidant/antipathogen agent in a retrospective case series. Brain, Behavior, & Immunity – Health (2024), doi: https://doi.org/10.1016/j.bbih.2023.100720 https://www.sciencedirect.com/science/article/pii/S2666354623001345 (Full text)

Long COVID, POTS, CFS and MTHFR: Linked by Biochemistry and Nutrition

Abstract:

The recent pandemic has energized research spotlighting chronic fatigue disorders. The similarities between Long COVID (LC) and Chronic Fatigue Syndrome (CFS), often accompanied by postural orthostatic tachycardia syndrome (POTS) are striking.

Furthermore, the majority afflicted with LC and CFS may be those with methylenetetrahydrofolate reductase (MTHFR) polymorphisms, present in the majority of Americans and characterized by hypomethylation. Elevated homocysteine (Hcy) and depressed B9 and B12 may be links. Speculation about an association between these laboratory analytes and MTHFR abnormalities has been previously reported (Regland et al., 2015).

The absence of a blood-brain barrier (BBB) in CNS circumventricular organs (CVOs) that control autonomic and neuroendocrine functions, problematic in LC, CFS, POTS, and MTHFR, is provocative. Diffusion of CNS Hcy is associated with brain fog, cognitive impairment, and dementia. This provides a distinct link between MTHFR variants and the fog of LC, CFS, and POTS.

Small intestine bacterial overgrowth (SIBO), present in about 17% of Americans, is linked to POTS, mast cell activation syndrome (MCAS), and Ehlers Danlos syndrome (EDS). All exhibit histamine intolerance and female predominance. This may be due to hypomethylation and/or intestinal diamine oxidase (DAO) deficiency.

Metabolism of monoamines and histamine requires methylation. Specific CNS nuclei in CVOs may also provide insight to the POTS paradox. The similar gut microbiomes of LC/CFS (and vitamin D deficiency) may via CVOs trigger an imbalance in glutamate/GABA neurotransmission that translates to neuroendocrine and baroreflex dysfunction. Homozygosity for the MTHFR 677T allele can facilitate hypermethylation via an alternative “rescue” riboflavin pathway triggered by significant Hcy increase.

Hypermethylation predominates in Long Covid. The primary problem in these syndromes is compromised mitochondrial function due to oxidative stress induced by an antioxidant shortfall.

Victims are also frequently deficient in 25(OH)D3 (the storage form of vitamin D), magnesium, and B vitamins, consumed by the persistent chronic inflammatory state. Estrogen increases histamine, norepinephrine, and bradykinin (BKN), which may in part explain the brain fog and its predilection for females.

Source: Patrick W Chambers. Long COVID, POTS, CFS and MTHFR: Linked by Biochemistry and Nutrition. Journal of Orthomolecular Medicine. 38. https://www.researchgate.net/publication/373073968_Long_Covid_POTS_CFS_and_MTHFR_Linked_by_Biochemistry_and_Nutrition#fullTextFileContent (Full text)

Amino acids, post-translational modifications, nitric oxide, and oxidative stress in serum and urine of long COVID and ex COVID human subjects

Abstract:

In this study, we investigated the status of amino acids, their post-translational modifications (PTM), major nitric oxide (NO) metabolites and of malondialdehyde (MDA) as a biomarker of oxidative stress in serum and urine samples of long COVID (LoCo, n = 124) and ex COVID (ExCo, n = 24) human subjects collected in 2022.

Amino acids and metabolites were measured by gas chromatography–mass spectrometry (GC–MS) methods using stable-isotope labelled analogs as internal standards. There were no differences with respect to circulating and excretory arginine and asymmetric dimethylarginine (ADMA). LoCo participants excreted higher amounts of guanidino acetate than ExCo participants (17.8 ± 10.4 µM/mM vs. 12.6 ± 8.86 µM/mM, P = 0.005). By contrast, LoCo participants excreted lower amounts of the advanced glycation end-product (AGE) NG-carboxyethylarginine (CEA) than ExCo participants did (0.675 ± 0.781 µM/mM vs. 1.16 ± 2.04 µM/mM, P = 0.0326).

The serum concentrations of MDA did not differ between the groups, indicating no elevated oxidative stress in LoCo or ExCo. The serum concentration of nitrite was lower in LoCo compared to ExCo (1.96 ± 0.92 µM vs. 2.56 ± 1.08 µM; AUC, 0.718), suggesting altered NO synthesis in the endothelium. The serum concentration of nitrite correlated inversely with the symptom anxiety (r = − 0.293, P = 0.0003). The creatinine-corrected urinary excretion of Lys and its metabolite L-5-hydroxy-Lys correlated positively with COVID toes (r = 0.306, P = 0.00027) and sore throat (r = 0.302, P = 0.0003).

Our results suggest that amino acid metabolism, PTM and oxidative stress are not severely affected in long COVID. LoCo participants may have a lower circulating NO reservoir than ExCo.

Source: Mikuteit, M., Baskal, S., Klawitter, S. et al. Amino acids, post-translational modifications, nitric oxide, and oxidative stress in serum and urine of long COVID and ex COVID human subjects. Amino Acids (2023). https://doi.org/10.1007/s00726-023-03305-1 https://link.springer.com/article/10.1007/s00726-023-03305-1 (Full text)

MTHFR and LC, CFS, POTS, MCAS, SIBO, EDS: Methylating the Alphabet

Abstract:

Long Covid (LC), Chronic Fatigue Syndrome (CFS), Postural Orthostatic Tachycardia Syndrome (POTS), Mast Cell Activation Syndrome (MCAS), Small Intestine Bacterial Overgrowth (SIBO), and Ehlers-Danlos Syndrome (EDS) are all loosely connected, some poorly defined, some with overlapping symptoms.

The female preponderance, the prominence of fatigue and chronic inflammation, and methylenetetrahydrofolate reductase (MTHFR) abnormalities may connect them all. Indeed differential methylation may lie at the root. Two – EDS and MTHFR – are genetic. But epigenetic factors may ultimately determine their phenotypic expression.

Oxidative stress, overloaded mitochondria, an antioxidant and nutrient shortfall, and suboptimal gut microbiome appear to be the primary determinants. A deep dive into the folate and methionine cycles is undertaken in an attempt to connect these syndromes.

The active forms of vitamin D and vitamins B2,3,6,9,12 are shown to be biochemically integral to optimal methylation and control of the epigenome. Their status largely determines the symptoms of abnormal MTHFR in all its phenotypes. The wider implications for aging, cancer, cardiovascular disease, neurodegenerative disease, and autoimmune disease are briefly explored.

Source: Chambers P. MTHFR and LC, CFS, POTS, MCAS, SIBO, EDS: Methylating the Alphabet. Preprint from Qeios, 30 Jun 2023. https://www.qeios.com/read/ZPYS4F (Full text)

Altered Lipid, Energy Metabolism and Oxidative Stress Are Common Features in a Range of Chronic Conditions

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), Gulf War Syndrome (GWS) and Fibromyalgia are chronic illnesses that, despite their prevalence in society, are still of unknown aetiology. All three conditions present similar clinical symptoms and are difficult to diagnose due to a lack of appropriate biomarkers. Currently, diagnosis consists of satisfying clinical criteria and eliminating other conditions, a lengthy and often costly process for patients. The discovery of biomarkers would significantly speed up patient diagnosis and allow the development of pharmacological therapies that target the underlying metabolic causes of these diseases.

Metabolomics is an emerging research area used to characterise the metabolites present within biological specimens. Developments within this field now allow the analysis of thousands of metabolites within different samples and model systems, and have the potential to aid in unravelling the metabolic phenotypes that underpin complex metabolic diseases. ME/CFS, GWS and Fibromyalgia are three conditions that could benefit from a plasma/tissue metabolomics analysis, allowing a greater understanding of their aetiology and identify common pathways. An analysis of the literature in these conditions reveals alterations within pathways associated with energy and lipid metabolism with alterations in key metabolites associated with elevated oxidative stress. Understanding what might drive the elevated oxidative stress within all three illnesses will not only be important in future research but could also be a potential therapeutic target for antioxidant medications which could be implemented to reduce the symptom burden in these illnesses.

Source: MORTEN, Karl Jonathan and Davis, Leah and Lodge, Tiffany A. and Strong, James and Espejo-Oltra, José Andrés and Zalewski, Pawel and Pretorius, Etheresia, Altered Lipid, Energy Metabolism and Oxidative Stress Are Common Features in a Range of Chronic Conditions. Available at SSRN: https://ssrn.com/abstract=4455366 or http://dx.doi.org/10.2139/ssrn.4455366 (Full text available as PDF file)

Ginkgo Biloba and Long COVID: In Vivo and In Vitro Models for the Evaluation of Nanotherapeutic Efficacy

Abstract:

Coronavirus infections are neuroinvasive and can provoke injury to the central nervous system (CNS) and long-term illness consequences. They may be associated with inflammatory processes due to cellular oxidative stress and an imbalanced antioxidant system. The ability of phytochemicals with antioxidant and anti-inflammatory activities, such as Ginkgo biloba, to alleviate neurological complications and brain tissue damage has attracted strong ongoing interest in the neurotherapeutic management of long COVID.
Ginkgo biloba leaf extract (EGb) contains several bioactive ingredients, e.g., bilobalide, quercetin, ginkgolides A–C, kaempferol, isorhamnetin, and luteolin. They have various pharmacological and medicinal effects, including memory and cognitive improvement. Ginkgo biloba, through its anti-apoptotic, antioxidant, and anti-inflammatory activities, impacts cognitive function and other illness conditions like those in long COVID. While preclinical research on the antioxidant therapies for neuroprotection has shown promising results, clinical translation remains slow due to several challenges (e.g., low drug bioavailability, limited half-life, instability, restricted delivery to target tissues, and poor antioxidant capacity).
This review emphasizes the advantages of nanotherapies using nanoparticle drug delivery approaches to overcome these challenges. Various experimental techniques shed light on the molecular mechanisms underlying the oxidative stress response in the nervous system and help comprehend the pathophysiology of the neurological sequelae of SARS-CoV-2 infection.
To develop novel therapeutic agents and drug delivery systems, several methods for mimicking oxidative stress conditions have been used (e.g., lipid peroxidation products, mitochondrial respiratory chain inhibitors, and models of ischemic brain damage). We hypothesize the beneficial effects of EGb in the neurotherapeutic management of long-term COVID-19 symptoms, evaluated using either in vitro cellular or in vivo animal models of oxidative stress.
Source: Akanchise T, Angelova A. Ginkgo Biloba and Long COVID: In Vivo and In Vitro Models for the Evaluation of Nanotherapeutic Efficacy. Pharmaceutics. 2023; 15(5):1562. https://doi.org/10.3390/pharmaceutics15051562 https://www.mdpi.com/1999-4923/15/5/1562 (Full text)

Possible Pathogenesis and Prevention of Long COVID: SARS-CoV-2-Induced Mitochondrial Disorder

Abstract:

Patients who have recovered from coronavirus disease 2019 (COVID-19) infection may experience chronic fatigue when exercising, despite no obvious heart or lung abnormalities. The present lack of effective treatments makes managing long COVID a major challenge.
One of the underlying mechanisms of long COVID may be mitochondrial dysfunction. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can alter the mitochondria responsible for energy production in cells. This alteration leads to mitochondrial dysfunction which, in turn, increases oxidative stress. Ultimately, this results in a loss of mitochondrial integrity and cell death. Moreover, viral proteins can bind to mitochondrial complexes, disrupting mitochondrial function and causing the immune cells to over-react. This over-reaction leads to inflammation and potentially long COVID symptoms.
It is important to note that the roles of mitochondrial damage and inflammatory responses caused by SARS-CoV-2 in the development of long COVID are still being elucidated. Targeting mitochondrial function may provide promising new clinical approaches for long-COVID patients; however, further studies are needed to evaluate the safety and efficacy of such approaches.
Source: Chen T-H, Chang C-J, Hung P-H. Possible Pathogenesis and Prevention of Long COVID: SARS-CoV-2-Induced Mitochondrial Disorder. International Journal of Molecular Sciences. 2023; 24(9):8034. https://doi.org/10.3390/ijms24098034 https://www.mdpi.com/1422-0067/24/9/8034 (Full text)

Astragalus polysaccharide ameliorated complex factor-induced chronic fatigue syndrome by modulating the gut microbiota and metabolites in mice

Abstract:

Chronic fatigue syndrome (CFS) is a debilitating disease with no symptomatic treatment. Astragalus polysaccharide (APS), a component derived from the traditional Chinese medicine A. membranaceus, has significant anti-fatigue activity. However, the mechanisms underlying the potential beneficial effects of APS on CFS remain poorly understood.

A CFS model of 6-week-old C57BL/6 male mice was established using the multiple-factor method. These mice underwent examinations for behavior, oxidative stress and inflammatory indicators in brain and intestinal tissues, and ileum histomorphology. 16 S rDNA sequencing analysis indicated that APS regulated the abundance of gut microbiota and increased production of short chain fatty acids (SCFAs) and anti-inflammatory bacteria.

In addition, APS reversed the abnormal expression of Nrf2, NF-κB, and their downstream factors in the brain-gut axis and alleviated the reduction in SCFAs in the cecal content caused by CFS. Further, APS modulated the changes in serum metabolic pathways induced by CFS.

Finally, it was verified that butyrate exerted antioxidant and anti-inflammatory effects in neuronal cells. In conclusion, APS could increase the SCFAs content by regulating the gut microbiota, and SCFAs (especially butyrate) can further regulate the oxidative stress and inflammation in the brain, thus alleviating CFS.

This study explored the efficacy and mechanism of APS for CFS from the perspective of gut-brain axis and provides a reference to further explore the efficacy of APS and the role of SCFAs in the central nervous system.

Source: Wei X, Xin J, Chen W, Wang J, Lv Y, Wei Y, Li Z, Ding Q, Shen Y, Xu X, Zhang X, Zhang W, Zu X. Astragalus polysaccharide ameliorated complex factor-induced chronic fatigue syndrome by modulating the gut microbiota and metabolites in mice. Biomed Pharmacother. 2023 May 9;163:114862. doi: 10.1016/j.biopha.2023.114862. Epub ahead of print. PMID: 37167729. https://www.sciencedirect.com/science/article/pii/S0753332223006522?via%3Dihub (Full study)