Tag: hypoxia

Possible Role of Fibrinaloid Microclots in Postural Orthostatic Tachycardia Syndrome (POTS): Focus on Long COVID

Abstract:

Postural orthostatic tachycardia syndrome (POTS) is a common accompaniment of a variety of chronic, inflammatory diseases, including long COVID, as are small, insoluble, ‘fibrinaloid’ microclots.
We here develop the argument, with accompanying evidence, that fibrinaloid microclots, through their ability to block the flow of blood through microcapillaries and thus cause tissue hypoxia, are not simply correlated with but in fact, by preceding it, may be a chief intermediary cause of POTS, in which tachycardia is simply the body’s exaggerated ‘physiological’ response to hypoxia. Similar reasoning accounts for the symptoms bundled under the term ‘fatigue’.
Amyloids are known to be membrane disruptors, and when their targets are nerve membranes, this can explain neurotoxicity and hence the autonomic nervous system dysfunction that contributes to POTS. Taken together as a system view, we indicate that fibrinaloid microclots can serve to link POTS and fatigue in long COVID in a manner that is at once both mechanistic and explanatory. This has clear implications for the treatment of such diseases.
Source: Kell DB, Khan MA, Kane B, Lip GYH, Pretorius E. Possible Role of Fibrinaloid Microclots in Postural Orthostatic Tachycardia Syndrome (POTS): Focus on Long COVID. Journal of Personalized Medicine. 2024; 14(2):170. https://doi.org/10.3390/jpm14020170 https://www.mdpi.com/2075-4426/14/2/170 (Full text)

Heterogenous circulating miRNA changes in ME/CFS converge on a unified cluster of target genes: A computational analysis

Abstract:

Myalgic Encephalomyelitis / Chronic Fatigue Syndrome is a debilitating, multisystem disease of unknown mechanism, with a currently ongoing search for its endocrine mediators. Circulating microRNAs (miRNA) are a promising candidate for such a mediator and have been reported as significantly different in the patient population versus healthy controls by multiple studies. None of these studies, however, agree with each other on which specific miRNA are under- or over-expressed.

This discrepancy is the subject of the computational study presented here, in which a deep dive into the predicted gene targets and their functional interactions is conducted, revealing that the aberrant circulating miRNAs in ME/CFS, although different between patients, seem to mainly target the same specific set of genes (p ≈ 0.0018), which are very functionally related to each other (p ≲ 0.0001).

Further analysis of these functional relations, based on directional pathway information, points to impairments in exercise hyperemia, angiogenic adaptations to hypoxia, antioxidant defenses, and TGF-β signaling, as well as a shift towards mitochondrial fission, corroborating and explaining previous direct observations in ME/CFS. Many transcription factors and epigenetic modulators are implicated as well, with currently uncertain downstream combinatory effects.

As the results show significant similarity to previous research on latent herpesvirus involvement in ME/CFS, the possibility of a herpesvirus origin of these miRNA changes is also explored through further computational analysis and literature review, showing that 8 out of the 10 most central miRNAs analyzed are known to be upregulated by various herpesviruses. In total, the results establish an appreciable and possibly central role for circulating microRNAs in ME/CFS etiology that merits further experimental research.

Source: Kaczmarek MP. Heterogenous circulating miRNA changes in ME/CFS converge on a unified cluster of target genes: A computational analysis. PLoS One. 2023 Dec 29;18(12):e0296060. doi: 10.1371/journal.pone.0296060. PMID: 38157384; PMCID: PMC10756525. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10756525/ (Full text)

Dysregulation of the Kynurenine Pathway, Cytokine Expression Pattern, and Proteomics Profile Link to Symptomology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Abstract:

Dysregulation of the kynurenine pathway (KP) is believed to play a significant role in neurodegenerative and cognitive disorders. While some evidence links the KP to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), further studies are needed to clarify the overall picture of how inflammation-driven KP disturbances may contribute to symptomology in ME/CFS.

Here, we report that plasma levels of most bioactive KP metabolites differed significantly between ME/CFS patients and healthy controls in a manner consistent with their known contribution to symptomology in other neurological disorders. Importantly, we found that enhanced production of the first KP metabolite, kynurenine (KYN), correlated with symptom severity, highlighting the relationship between inflammation, KP dysregulation, and ME/CFS symptomology.

Other significant changes in the KP included lower levels of the downstream KP metabolites 3-HK, 3-HAA, QUIN, and PIC that could negatively impact cellular energetics. We also rationalized KP dysregulation to changes in the expression of inflammatory cytokines and, for the first time, assessed levels of the iron (Fe)-regulating hormone hepcidin that is also inflammation-responsive. Levels of hepcidin in ME/CFS decreased nearly by half, which might reflect systemic low Fe levels or possibly ongoing hypoxia.

We next performed a proteomics screen to survey for other significant differences in protein expression in ME/CFS. Interestingly, out of the seven most significantly modulated proteins in ME/CFS patient plasma, 5 proteins have roles in maintaining gut health, which considering the new appreciation of how gut microbiome and health modulates systemic KP could highlight a new explanation of symptomology in ME/CFS patients and potential new prognostic biomarker/s and/or treatment avenues.

Source: Kavyani B, Ahn SB, Missailidis D, Annesley SJ, Fisher PR, Schloeffel R, Guillemin GJ, Lovejoy DB, Heng B. Dysregulation of the Kynurenine Pathway, Cytokine Expression Pattern, and Proteomics Profile Link to Symptomology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Mol Neurobiol. 2023 Nov 28. doi: 10.1007/s12035-023-03784-z. Epub ahead of print. PMID: 38015302. https://pubmed.ncbi.nlm.nih.gov/38015302/

Long-Term cognitive dysfunction after the COVID-19 pandemic: a narrative review

Abstract:

Introduction: SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has brought a conglomerate of novel chronic disabling conditions described as ‘Long COVID/Post-COVID-19 Syndrome’. Recent evidence suggests that the multifaceted nature of this syndrome results in both pulmonary and extrapulmonary sequelae, chronic dyspnoea, persistent fatigue, and cognitive dysfunction being the most common, debilitating symptoms. Several mechanisms engender or exacerbate cognitive impairment, including central nervous system (CNS) and extra-CNS causes, although the exact mechanism remains unclear. Both hospitalized and non-hospitalized patients may suffer varying degrees of cognitive impairment, ranging from fatigue and brain fog to prolonged deficits in memory and attention, detrimental to the quality-of-life years post-recovery. The aim of this review is to understand the underlying mechanisms, associations, and attempts for prevention with early intervention of long-term cognitive impairment post-COVID-19.

Methodology: A systematic search was conducted through multiple databases such as Medline, National Library of Medicine, Ovid, Scopus database to retrieve all the articles on the long term sequalae of cognitive dysfunction after Sars-Cov2 infection. The inclusion criteria included all articles pertinent to this specific topic and exclusion criteria subtracted studies pertaining to other aetiologies of cognitive dysfunction. This search was carefully screened for duplicates and the relevant information was extracted and analysed.

Results/discussion: To date, the exact pathogenesis, and underlying mechanisms behind cognitive dysfunction in COVID-19, remain unclear, hindering the development of adequate management strategies. However, the proposed mechanisms suggested by various studies include direct damage to the blood-brain barrier, systemic inflammation, prolonged hypoxia, and extended intensive care admissions. However, no clear-cut guidelines for management are apparent.

Conclusion: This review of the COVID-19 pandemic has elucidated a new global challenge which is affecting individuals’ quality of life by inducing long-term impaired cognitive function. We have found that comprehensive evaluations and interventions are crucial to address the cognitive sequelae in all COVID-19 patients, especially in patients with pre-existing cognitive impairment. Nevertheless, the authors recommend further research for the development of relevant, timely neurocognitive assessments and treatment plans.

Source: Shariff, Sanobar; Uwishema, Olivier; Mizero, Jocelyn; Devi Thambi, Vimala; Nazir, Abubakar; Mahmoud, Ashraf; Kaushik, Ikshwaki; Khayat, Saadeddine; Yusif Maigoro, Abdulkadir; Awde, Sara; Al Maaz, Zeina; Alwan, Iktimal; Hijazi, Mahdi; Wellington, Jack MSc (LSHTM) FGMS; Soojin, Lee. Long-Term cognitive dysfunction after the COVID-19 pandemic: a narrative review. Annals of Medicine & Surgery ():10.1097/MS9.0000000000001265, September 8, 2023. | DOI: 10.1097/MS9.0000000000001265 https://journals.lww.com/annals-of-medicine-and-surgery/abstract/9900/long_term_cognitive_dysfunction_after_the_covid_19.1011.aspx

Role of Janus Kinase inhibitors in the management of pulmonary involvement due to Long COVID-19 disease: A case control study

Abstract:

Objectives: Ongoing symptomatic coronavirus disease 2019 (OSC) is defined as persistent symptoms beyond 4 weeks of acute illness. OSC leads to prolonged hospitalization and oxygen dependence. We aimed to find the outcome of Janus kinase inhibitors (JAKi) as a steroid-sparing agent to treat OSC.

Methods: In this single-center case-controlled study comparing JAKi and corticosteroids in OSC cases, data of 41 cases out of 86 were included – 21 in the JAKi group and 20 in the corticosteroid group from 4 weeks of acute illness to the next 4 weeks. Clinical parameters and inflammatory markers were recorded. The primary outcome was to compare the proportion of patients who were able to maintain oxygen saturation ≥95% with any oxygen supplementation in the two groups.

Results: The baseline clinical and demographic characteristics were similar in the two groups. The age was 53.65 ± 9.8 years and 51.48 ± 14.0 years in the corticosteroid group and JAKi group, respectively. At the baseline, 85% of patients in the corticosteroid group and 85.8% in the JAKi group were on oxygen support. The most common symptom in both groups was breathlessness followed by cough. Twenty percent of patients in the JAKi group received baricitinib and the remaining were given tofacitinib. At the time of follow-up, the majority of cases had a significant reduction in C-reactive protein (CRP) and D-dimer; however, the change in CRP and D-dimer was similar in both groups. The number of patients off oxygen support at 4 weeks was higher in the JAKi group (85% in the corticosteroid group vs. 95.2% in the JAKi group, P = 0.269), and the median time to liberation from oxygen support was significantly lower in JAKi group (19 days in corticosteroid group vs. 9 days in JAKi group, P < 0.001). The frequency of any adverse event was also higher in the corticosteroid group (70% vs. 23.8%, P = 0.003).

Conclusion: JAKi can be used as immunomodulatory drugs in hypoxic OSC cases having evidence of ongoing inflammation.

Source: Singh PK, Sharma VK, Lalwani LK, Chaudhry D, Govindagoudar MB, Sriram CP, Ahuja A. Role of Janus Kinase inhibitors in the management of pulmonary involvement due to Long COVID-19 disease: A case control study. Turk J Emerg Med. 2023 Jun 26;23(3):149-155. doi: 10.4103/tjem.tjem_363_22. PMID: 37529783; PMCID: PMC10389097. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10389097/ (Full text)

Initial COVID-19 Severity and Long-COVID Manifestations: An Observational Analysis

Abstract:

Objective: New-onset or persistent symptoms beyond after 4 weeks from COVID-19 are termed “long-COVID.” Whether the initial severity of COVID-19 has a bearing on the clinicoradiological manifestations of long COVID is an area of interest.

Material and methods: We did an observational analysis of the long-COVID patients after categorizing them based on their course of COVID-19 illness into mild, moderate, and severe groups. The clinical and radiological profile was compared across these groups.

Results: Out of 150 long-COVID patients recruited in the study, about 79% (118), 14% (22), and 7% (10) had a history of mild, moderate, and severe COVID-19, respectively. Fatigue (P = .001), breathlessness (P = .001), tachycardia (P = .002), tachypnea (P < .001), raised blood pressure (P < .001), crepitations (P = .04), hypoxia at rest (P < .001), significant desaturation in 6-minute walk test (P = .27), type 1 respiratory failure (P = .001), and type 2 respiratory failure (P = .001) were found to be significantly higher in the long-COVID patients with a history of severe COVID-19. These patients also had the highest prevalence of abnormal chest X-ray (60%) and honeycombing in computed tomography scan thorax (25%, P = .027).

Conclusion: The course of long COVID bears a relationship with initial COVID-19 severity. Patients with severe COVID-19 are prone to develop more serious long-COVID manifestations.

Source: Goel N, Goyal N, Spalgais S, Mrigpuri P, Varma-Basil M, Khanna M, Nagaraja R, Menon B, Kumar R. Initial COVID-19 Severity and Long-COVID Manifestations: An Observational Analysis. Thorac Res Pract. 2023 Jan;24(1):22-28. doi: 10.5152/ThoracResPract.2023.21307. PMID: 37503595. https://thoracrespract.org/en/initial-covid-19-severity-and-long-covid-manifestations-an-observational-analysis-165530 (Full text as PDF file)

Mitigating neurological, cognitive, and psychiatric sequelae of COVID-19-related critical illness

Abstract:

Despite advances in the treatment and mitigation of critical illness caused by infection with SARS-CoV-2, millions of survivors have a devastating, post-acute infection syndrome known as long COVID. A large proportion of patients with long COVID have nervous system dysfunction, which is also seen in the distinct but overlapping condition of post-intensive care syndrome (PICS), putting survivors of COVID-19-related critical illness at high risk of long-lasting morbidity affecting multiple organ systems and, as a result, engendering measurable deficits in quality of life and productivity.

In this Series paper, we discuss neurological, cognitive, and psychiatric sequelae in patients who have survived critical illness due to COVID-19. We review current knowledge of the epidemiology and pathophysiology of persistent neuropsychological impairments, and outline potential preventive strategies based on safe, evidence-based approaches to the management of pain, agitation, delirium, anticoagulation, and ventilator weaning during critical illness. We highlight priorities for current and future research, including possible therapeutic approaches, and offer considerations for health services to address the escalating health burden of long COVID.

Source: Pandharipande P, Williams Roberson S, Harrison FE, Wilson JE, Bastarache JA, Ely EW. Mitigating neurological, cognitive, and psychiatric sequelae of COVID-19-related critical illness. Lancet Respir Med. 2023 Jul 17:S2213-2600(23)00238-2. doi: 10.1016/S2213-2600(23)00238-2. Epub ahead of print. PMID: 37475124. https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(23)00238-2/fulltext (Full text)

Carotid body dysregulation contributes to the enigma of long COVID

Abstract:

The symptoms of long COVID, which include fatigue, breathlessness, dysregulated breathing, and exercise intolerance, have unknown mechanisms. These symptoms are also observed in heart failure and are partially driven by increased sensitivity of the carotid chemoreflex. As the carotid body has an abundance of ACE2 (the cell entry mechanism for SARS-CoV-2), we investigated whether carotid chemoreflex sensitivity was elevated in participants with long COVID. During cardiopulmonary exercise testing, the VE/VCO2 slope (a measure of breathing efficiency) was higher in the long COVID group than in the controls, indicating excessive hyperventilation.

The hypoxic ventilatory response, which measures carotid chemoreflex sensitivity, was increased in long COVID participants and correlated with the VE/VCO2 slope, suggesting that excessive hyperventilation may be related to carotid body hypersensitivity. Therefore, the carotid chemoreflex is sensitized in long COVID and may explain dysregulated breathing and exercise intolerance in these participants. Tempering carotid body excitability may be a viable treatment option for long COVID patients.

Source: Ahmed El-Medany, Zoe H Adams, Hazel C Blythe, Katrina A Hope, Adrian H Kendrick, Ana Paula Abdala Sheikh, Julian FR Paton, Angus K Nightingale, Emma C Hart. Carotid body dysregulation contributes to the enigma of long COVID. medRxiv 2023.05.25.23290513; doi: https://doi.org/10.1101/2023.05.25.23290513 https://www.medrxiv.org/content/10.1101/2023.05.25.23290513v1.full-text (Full text)

Long COVID: pathophysiological factors and abnormalities of coagulation

Abstract:

Acute COVID-19 infection is followed by prolonged symptoms in approximately one in ten cases: known as Long COVID. The disease affects ~65 million individuals worldwide. Many pathophysiological processes appear to underlie Long COVID, including viral factors (persistence, reactivation, and bacteriophagic action of SARS CoV-2); host factors (chronic inflammation, metabolic and endocrine dysregulation, immune dysregulation, and autoimmunity); and downstream impacts (tissue damage from the initial infection, tissue hypoxia, host dysbiosis, and autonomic nervous system dysfunction). These mechanisms culminate in the long-term persistence of the disorder characterized by a thrombotic endothelialitis, endothelial inflammation, hyperactivated platelets, and fibrinaloid microclots. These abnormalities of blood vessels and coagulation affect every organ system and represent a unifying pathway for the various symptoms of Long COVID.

Source: Simone Turner, Asad Khan, David Putrino, Ashley Woodcock, Douglas B. Kell, and Etheresia Pretorius.  Long COVID: pathophysiological factors and abnormalities of coagulation. Trends in Endocrinology & Metabolism. April 19, 2023. https://www.sciencedirect.com/science/article/pii/S1043276023000553 (Full text)

Direct and indirect impact of SARS-CoV-2 on the brain

Abstract:

Although COVID-19 is mostly a pulmonary disease, it is now well accepted that it can cause a much broader spectrum of signs and symptoms and affect many other organs and tissue. From mild anosmia to severe ischemic stroke, the impact of SARS-CoV-2 on the central nervous system is still a great challenge to scientists and health care practitioners.

Besides the acute and severe neurological problems described, as encephalopathies, leptomeningitis, and stroke, after 2 years of pandemic, the chronic impact observed during long-COVID or the post-acute sequelae of COVID-19 (PASC) greatly intrigues scientists worldwide. Strikingly, even asymptomatic, and mild diseased patients may evolve with important neurological and psychiatric symptoms, as confusion, memory loss, cognitive decline, chronic fatigue, associated or not with anxiety and depression. Thus, the knowledge on the correlation between COVID-19 and the central nervous system is of great relevance.

In this sense, here we discuss some important mechanisms obtained from in vitro and in vivo investigation regarding how SARS-CoV-2 impacts the brain and its cells and function.

Source: Peron JPS. Direct and indirect impact of SARS-CoV-2 on the brain. Hum Genet. 2023 Apr 1:1–10. doi: 10.1007/s00439-023-02549-x. Epub ahead of print. PMID: 37004544; PMCID: PMC10066989. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10066989/ (Full text)