Greater Role of Cognitive Impairment Over Fatigue in Post-COVID-19 Quality of Life: A Post-Hoc Analysis of a Randomized Controlled Trial (preprint)

BackgroundPost COVID-19 Condition (PCC) is a common and debilitating condition with significant reports of fatigue and psychosocial impairment globally. The extent to which cognitive symptoms and fatigue contribute to reduced quality of life in affected individuals remains clear. MethodsThis is a post-hoc analysis of a randomized, double-blind, placebo-controlled clinical trial that evaluated the effect of vortioxetine on cognitive function in adults with PCC. The post-hoc analysis herein aimed to determine the overall effect of baseline cognitive function [as measured by the Digit Symbol Substitution Test (DSST)] and baseline fatigue severity [as measured by the Fatigue Severity Scale (FSS)] on baseline health-related quality of life (HRQoL) [as measured by the 5-item World Health Organisation Well-Being Index (WHO-5)]. ResultsA total of 200 participants were enrolled in the primary trial. Due to missing baseline data, our statistical analysis included baseline measures of 147 individuals. Our generalized linear model analysis revealed a significant positive correlation between DSST-measured objective cognitive function and self-reported WHO-5-measured HRQoL ({beta} = 0.069, 95% CI [0.006, 0.131], p = 0.032). In contrast, our analysis revealed a significant negative correlation between FSS and WHO-5 scores ({beta} = -0.016, 95% CI [-0.021, -0.011], p < 0.001). The beta-coefficient ratio ({beta}DSST / {beta}FSS = 0.069 / 0.016) is calculated as 4.313. ConclusionsOverall, we observed that increased cognitive function was associated with increased HRQoL at baseline in adults with PCC. Moreover, we observed that increased severity of fatigue symptoms was associated with decreased HRQoL at baseline in adults with PCC. Furthermore, we observed that an improvement in cognitive function would have a four-fold greater impact on HRQoL than the effect generated by improvement in fatigue.

PFC/M1 activation and excitability: a longitudinal cohort study on fatigue symptoms in healthcare workers post-COVID-19 (preprint)

Background Fatigue is one of the most common neurological symptoms reported post coronavirus disease 2019 (COVID-19) infection. In order to establish effective early intervention strategies, more emphasis should be placed on the correlation between fatigue and cortical neurophysiological changes, especially in healthcare workers, who are at a heightened risk of COVID-19 infection.Methods A prospective cohort study was conducted involving 29 COVID-19 medical workers and 24 healthy controls. The assessment included fatigue, sleep and health quality, psychological status, and physical capacity. Functional near-infrared spectroscopy (fNIRS) was employed to detect activation of brain regions. Bilateral primary motor cortex (M1) excitabilities were measured using single- and paired-pulse transcranial magnetic stimulation. Outcomes were assessed at 1, 3, and 6 months into the disease course.Results At 1-month post-COVID-19 infection, 37.9% of patients experienced severe fatigue symptoms, dropping to 10.3% at 3 months. Interestingly, the remarkable decreased activation/excitability of bilateral prefrontal lobe (PFC) and M1 were closely linked to fatigue symptoms after COVID-19. Notably, greater increase in M1 region excitability correlated with more significant fatigue improvement. Re-infected patients exhibited lower levels of brain activation and excitability compared to single-infection patients.Conclusions Both single infection and reinfection of COVID-19 lead to decreased activation and excitability of the PFC and M1. The degree of excitability improvement in the M1 region correlates with a greater recovery in fatigue. Based on these findings, targeted interventions to enhance and regulate the excitability of M1 may represent a novel strategy for COVID-19 early rehabilitation.Trial registration The Ethics Review Committee of Xijing Hospital, No. KY20232051-F-1, registered February 3, 2023. The Chinese Clinical Trial Registry, ChiCTR2300068444, registered February 20, 2023. https://www.chictr.org.cn

Repeated Hand Grip Strength is an Objective Marker for Disability and Severity of Key Symptoms in Post-COVID ME/CFS (preprint)

Post-COVID Syndrome (PCS) refers to a diverse array of symptoms that persist beyond 3 months of the acute phase of a SARS-CoV-2 infection. The most frequent symptom is fatigue, which can manifest both mentally and physically. In this study, handgrip strength (HGS) parameters were determined as an objective measure of muscle fatigue and fatigability. HGS parameters were correlated with other fre-quent symptoms among 144 female PCS patients suffering from fatigue, exertional intolerance, and cognitive impairment. Seventy-eight patients met the Canadian Consensus Criteria (CCC) for post-infectious myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The severity of disa-bility and key symptoms were evaluated utilizing self-reported questionnaires. Notably, patients di-agnosed with ME/CFS exhibited a higher overall severity of symptoms, including lower physical func-tion (p < 0.001), a greater degree of disability (p < 0.001), more severe fatigue (p < 0.001), post-exertional malaise (p < 0.001), and autonomic dysfunction (p = 0.004). While HGS was similarly impaired in both PCS and ME/CFS patients, the associations between HGS and the severity of symptoms and disability revealed striking differences. We observed significant correlations of HGS parameters with physical function across all patients, but with the key symptoms PEM, fatigue, cog-nitive impairment, and autonomic dysfunction in ME/CFS patients only. This points to a common mechanism for these symptoms in the ME/CFS subtype, distinct from that in other types of PCS. Further HGS provides an objective marker of disease severity in ME/CFS.

SARS-CoV-2 RNA-dependent RNA Polymerase is Linked to Mitochondrial Dysfunction in Mouse Heart (preprint)

Little is known about specific viral factors responsible for the pathogenesis and pathophysiology of long COVID. Here we describe a conditional knock-in (cKI) mouse strain inducibly expressing Nsp12, an essential component of SARS-CoV-2 RNA-dependent RNA polymerase (RdRp). Induction of Nsp12 translation was dependent on co-treatment with inhibitors of the integrated stress response in vitro and in vivo. We show that Nsp12 has a biologically significant link to mitochondrial dysfunction in vivo. In vitro, ectopic Nsp12 expression suppressed mitochondrial function in primary lung epithelial cells isolated from Nsp12 cKI mice. This functionality was physiologically relevant because, although ectopic Nsp12 expression in mouse lungs did not induce pneumonia, it did decrease mitochondrial activity in the hearts of Nsp12 cKI mice over the short and long terms. Administration in vivo of an RdRp inhibitor, EIDD-2801, restored mitochondrial function in cardiomyocytes of Nsp12 cKI mice. Our data demonstrate that SARS-CoV-2 RdRp activity in the lungs leads to cardiac mitochondrial dysfunction in vivo, generating a phenotype resembling aspects of long COVID in humans. Therapeutic targeting of SARS-CoV-2 RdRp may thus represent a novel means of preventing or mitigating intense fatigue and/or myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)-like disease caused by mitochondrial dysfunction in long COVID patients.

Long COVID Disability Burden in US Adults: YLDs and NIH Funding Relative to Other Conditions (preprint)

BackgroundLong COVID (LC) is novel, debilitating and likely chronic. Yet, scant data exist about its disability burden to guide scientific research and public health planning. We estimated Long COVIDs non-fatal disease burden in US adults and its FY2024 actual: burden-commensurate research funding from the National Institutes of Health (NIH) relative to other conditions, and biological sex. MethodsWe present YLDs/100,000 for 70 NIH Research, Condition, and Disease Categories (RCDCs). Prevalence of disabling Long COVID was obtained from cross sectional surveys of representative samples of US adults, from September 2022 to August 2023. Disabling Long COVID was defined as incident symptoms persisting more than 3 months post-COVID, that significantly compromise daily activities. We calculated burden-commensurate funding for the top YLD conditions and for female vs. male dominant conditions. FindingsDisabling Long COVID was reported by 1.5% (n= 10,401) of n=757,580 respondents: Compared to the overall sample, those with disabling LC disproportionately identify as female (64.4% vs. 51.4%) and experiencing disability (80.8% vs. 52.9%) anxiety (57.5% vs. 23.8%) and depression (51.3% vs.18.5%). It ranked in the top 25% of YLDs at 320/100,000, between Alzheimers (279.4/100,000) and asthma (355.7/100,000) but received just 10% of its actual: YLD-commensurate funding. Only 5 conditions received less actual: burden: commensurate funding, including Myalgic Encephalitis/Chronic Fatigue Syndrome (<1%), another post-viral, female-dominant condition. InterpretationLC has debilitated 3.8 million (weighted frequency) US adults. Research funding for it, like other female dominant conditions, lags behind its disability burden. Research in ContextEvidence before this study - We analyzed Long-COVIDs (LC) non-fatal disease burden in the US--represented by YLD (years lived with disability= prevalence x disability weight) -- and National Institutes of Health (NIH) research 2024 funding relative to other conditions. We searched PubMed through 11/28/2023 for Long COVID prevalence (US), and Long COVID disability and disease burden (not US-specific). The keywords "years lived with disability" + "COVID" yielded n= 38 articles (11/29/23); but most referenced "disability-adjusted life years" (DALYs) in other countries. Similarly, "disease burden" + Long COVID yielded 23 papers, but no US YLD data. See Supplement 1 for meta-analyses, systematic reviews and US studies of Long COVID prevalence and impact. We instead sourced YLD data from the US Census Bureaus Household Pulse Survey (HPS) and the Institute for Health Metrics and Evaluation (IHME) /Global Burden of Disease (GBD) Long COVID Study Group. The HPS queries adults about Long COVID-related symptoms and their impact on daily activities. We applied the IHME/GBDs estimated Long COVID disability weight of 0.21 and harmonized it with our LC case definition from the HPS data in consultation with IHME/GBD researchers. To harmonize IHME/GBD disability weights for non-LC diseases/conditions with the NIHs terminology, we consulted with NIH staff. LC definition and measurement affects prevalence and burden estimates; our use of high-quality data sources and transparency in reporting how they were applied reduces the risk of biased assumptions. Added value of this study- Long COVID is a chronic debilitating condition. While there is ample research on COVIDs acute illness and loss of life, there are no population-based data on its disability burden. We provide that data. To guide scientific research and public health planning, we report YLDs associated with disabling Long COVID (i.e., symptoms significantly limit activity), and; compare it to other conditions YLDs, NIH funding, and female-vs. male-dominance. It ranked in the top 25% of YLDs at 320/100,000, between Alzheimers (279.4/100,000) and asthma (355.7/100,000) but received just 10% of its YLD-commensurate funding. Only 5 conditions received less burden-commensurate funding; 3/5 were female-dominant, including Myalgic Encephalitis/Chronic Fatigue Syndrome (ME/CFS) at <1%, another post-viral condition that shares significant overlap with Long COVID. Overall, median funding/YLD was >= 5 times greater for male-vs. female-dominant conditions. Implications of all the available evidence-Nearly 4 million US adults (weighted frequency) live with disabling Long COVID. They disproportionately identify as female and as having a disability, anxiety and depression. Yet NIH funding for diagnostic and treatment research for Long COVID hasnt kept pace with its disability burden.

An AI-enabled Bias-Free Respiratory Disease Diagnosis Model using Cough Audio: A Case Study for COVID-19 (preprint)

Cough-based diagnosis for Respiratory Diseases (RDs) using Artificial Intelligence (AI) has attracted considerable attention, yet many existing studies overlook confounding variables in their predictive models. These variables can distort the relationship between cough recordings (input data) and RD status (output variable), leading to biased associations and unrealistic model performance. To address this gap, we propose the Bias Free Network (RBFNet), an end to end solution that effectively mitigates the impact of confounders in the training data distribution. RBFNet ensures accurate and unbiased RD diagnosis features, emphasizing its relevance by incorporating a COVID19 dataset in this study. This approach aims to enhance the reliability of AI based RD diagnosis models by navigating the challenges posed by confounding variables. A hybrid of a Convolutional Neural Networks (CNN) and Long-Short Term Memory (LSTM) networks is proposed for the feature encoder module of RBFNet. An additional bias predictor is incorporated in the classification scheme to formulate a conditional Generative Adversarial Network (cGAN) which helps in decorrelating the impact of confounding variables from RD prediction. The merit of RBFNet is demonstrated by comparing classification performance with State of The Art (SoTA) Deep Learning (DL) model (CNN LSTM) after training on different unbalanced COVID-19 data sets, created by using a large scale proprietary cough data set. RBF-Net proved its robustness against extremely biased training scenarios by achieving test set accuracies of 84.1%, 84.6%, and 80.5% for the following confounding variables gender, age, and smoking status, respectively. RBF-Net outperforms the CNN-LSTM model test set accuracies by 5.5%, 7.7%, and 8.2%, respectively

Microvascular Capillary and Precapillary Cardiovascular Disturbances Strongly Interact to Severely Affect Tissue Perfusion and Mitochondrial Function in ME/CFS Evolving from the Post COVID-19 Syndrome (preprint)

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a frequent, debilitating and still enigmatic disease. There is a broad overlap in the symptomatology of ME/CFS and the Post-COVID Syndrome (PCS). A fraction of the PCS patients develops the full clinical picture of ME/CFS. New observations in microvessels and blood from patients suffering from PCS have appeared and include microclots and malformed pathological blood cells. Capillary blood flow is impaired not only by pathological blood components but also by prothrombotic changes in the vascular wall, endothelial dysfunction, and expression of adhesion molecules in the capillaries. These disturbances can finally cause a low capillary flow and even capillary stasis. A low cardiac stroke volume due to hypovolemia and the inability of the capacitance vessels to adequately constrict to deliver the necessary cardiac preload generate an unfavorable low precapillary perfusion pressure. Furthermore, a predominance of vasoconstrictor over vasodilator influences exists, in which sympathetic hyperactivity and endothelial dysfunction play a strong role, causing constriction of resistance vessels and of precapillary sphincters which leads to a fall in capillary pressure behind the sphincters. The interaction of these two precapillary cardiovascular mechanisms causing a low capillary perfusion pressure is hemodynamically highly unfavorable in the presence of a primary capillary stasis already caused by the pathological blood components and their interaction with the capillary wall, to severely impair organ perfusion. The detrimental coincidence of the microcirculatory with the precapillary cardiovascular disturbances may constitute the key disturbance of the Post-COVID-19 syndrome and finally lead to ME/CFS in pre-disposed patients because the interaction causes a particular kind of perfusion disturbance - capillary ischemia-reperfusion - which has a high potential of causing mitochondrial dysfunction by inducing sodium- and calcium-overload in skeletal muscles. The latter in turns worsens the vascular situation by the generation of reactive oxygen species to close a vicious cycle from which the patient can hardly escape.

Association of circulating biomarkers with illness severity measures differentiates myalgic encephalomyelitis/chronic fatigue syndrome and post-COVID-19 condition: a prospective cohort study (preprint)

Background Accumulating evidence suggests that autonomic dysfunction and persistent systemic inflammation are common clinical features in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID. However, there is limited knowledge regarding their potential association with circulating biomarkers and illness severity status.Methods This prospective, cross-sectional, case-control cohort study aimed to distinguish between the two patient populations by using self-reported outcome measures and circulating biomarkers to assess endothelial function and systemic inflammation. Thirty-one individuals with ME/CFS, 23 individuals with long COVID, and 31 matched healthy subjects were included. Regression analysis was used to examine associations between self-reported outcome measures and circulating biomarkers in study participants. Classification across groups was based on principal component and discriminant analyses.Results Four ME/CFS patients (13%), 1 with long COVID (4%), and 1 healthy control (3%) presented postural orthostatic tachycardia syndrome (POTS) with the 10-min NASA lean test. Compared with healthy controls, ME/CFS and long COVID subjects showed higher levels of ET-1 (p < 0.05) and VCAM-1 (p < 0.001), and lower levels of nitrites (NOx assessed as NO2- + NO3-) (p < 0.01). ME/CFS patients also showed higher levels of serpin E1 (PAI-1) and E-selectin than did both long COVID and control subjects (p < 0.01 in all cases). Long COVID patients had lower TSP-1 levels than did ME/CFS patients and healthy controls (p < 0.001). As for inflammation biomarkers, both long COVID and ME/CFS subjects had higher levels of TNF-α than did healthy controls (p < 0.01 in both comparisons). Compared with controls, ME/CFS patients had higher levels of IL-1β (p < 0.001), IL-4 (p < 0.001), IL-6 (p < 0.01), IL-10 (p < 0.001), IP-10 (p < 0.05), and leptin (p < 0.001). Principal component analysis supported differentiation between groups based on self-reported outcome measures and endothelial and inflammatory biomarkers.Conclusions Our findings revealed that combining biomarkers of endothelial dysfunction and inflammation with outcome measures differentiate ME/CFS and Long COVID using robust discriminant analysis of principal components. Further research is needed to provide a more comprehensive characterization of these underlying pathomechanisms, which could be promising targets for therapeutic and preventive strategies in these conditions.

Brain-targeted autoimmunity is strongly associated with Long COVID and its chronic fatigue syndrome as well as its affective symptoms. (preprint)

Background: Autoimmune responses contribute to the pathophysiology of Long COVID, affective symptoms and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Objectives: To examine whether Long COVID, and its accompanying affective symptoms and CFS are associated with immunoglobulin (Ig)A/IgM/IgG directed at neuronal proteins including myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG), synapsin, +{beta}-tubulin, neurofilament protein (NFP), cerebellar protein-2 (CP2), and the blood-brain-barrier-brain-damage (BBD) proteins claudin-5 and S100B. Methods: IgA/IgM/IgG to the above neuronal proteins, human herpes virus-6 (HHV-6) and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) were measured in 90 Long COVID patients and 90 healthy controls, while C-reactive protein (CRP), and advanced oxidation protein products (AOPP) in association with affective and CFS ratings were additionally assessed in a subgroup thereof. Results: Long COVID is associated with significant increases in IgG directed at tubulin (IgG-tubulin), MBP, MOG and synapsin; IgM-MBP, MOG, CP2, synapsin and BBD; and IgA-CP2 and synapsin. IgM-SARS-CoV-2 and IgM-HHV-6 antibody titers were significantly correlated with IgA/IgG/IgM-tubulin and -CP2, IgG/IgM-BBD, IgM-MOG, IgA/IgM-NFP, and IgG/IgM-synapsin. Binary logistic regression analysis shows that IgM-MBP and IgG-MBP are the best predictors of Long COVID. Multiple regression analysis shows that IgG-MOG, CRP and AOPP explain together 41.7% of the variance in the severity of CFS. Neural network analysis shows that IgM-synapsin, IgA-MBP, IgG-MOG, IgA-synapsin, IgA-CP2, IgG-MBP and CRP are the most important predictors of affective symptoms due to Long COVID with a predictive accuracy of r=0.801. Conclusion: Brain-targeted autoimmunity contributes significantly to the pathogenesis of Long COVID and the severity of its physio-affective phenome.

Observational Study of Repeat Immunoadsorption (RIA) in Post-COVID ME/CFS Patients with Elevated Beta-2-Adrenergic Receptor Autoantibodies (preprint)

There is increasing evidence for an autoimmune aetiology in post-infectious Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). SARS-CoV-2 has now become the main trigger for ME/CFS. We have already conducted two small proof-of-concept studies of IgG depletion by immunoadsorption (IA) in post-infectious ME/CFS, which showed efficacy in most patients. This observational study aims to evaluate the efficacy of IA in patients with post-COVID-19 ME/CFS. The primary objective is to assess the improvement in functional ability. Due to the urgency of finding therapies for post-Covid-Syndrome (PCS), we report here the interim results of the first ten patients with seven responders defined by an increase of between 10 and 35 points in the Short-Form 36 Physical Function (SF36-PF) at week four after IA. The results of this observational study will provide the basis for patient selection for a randomised controlled trial (RTC) including sham apheresis and for a RTC combining IA with B-cell depletion therapy.

Pediatric and Adult Patients with ME/CFS following COVID-19: A Structured Approach to Diagnosis Using the Munich Berlin Symptom Questionnaire (MBSQ) (preprint)

PurposeA subset of patients with post-COVID-19 condition (PCC) fulfill the clinical criteria of myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS). To establish the diagnosis of ME/CFS for clinical and research purposes, comprehensive scores have to be evaluated. MethodsWe developed the Munich Berlin Symptom Questionnaires (MBSQs) and supplementary scoring sheets (SSSs) to allow for a rapid evaluation of common ME/CFS case definitions. The MBSQs were applied to young patients with chronic fatigue and post-exertional malaise (PEM) who presented to the MRI Chronic Fatigue Center for Young People (MCFC). Trials were retrospectively registered (NCT05778006, NCT05638724). ResultsUsing the MBSQs and SSSs, we report on ten patients aged 11 to 25 years diagnosed with ME/CFS after asymptomatic SARS-CoV-2 infection or mild to moderate COVID-19. Results from their MBSQs and from well-established patient-reported outcome measures indicated severe impairments of daily activities and health-related quality of life. ConclusionsME/CFS can follow SARS-CoV-2 infection in patients younger than 18 years, rendering structured diagnostic approaches most relevant for pediatric PCC clinics. The MBSQs and SSSs represent novel diagnostic tools that can facilitate the diagnosis of ME/CFS in children, adolescents, and adults with PCC and other post-viral syndromes. What is knownME/CFS is a frequent debilitating illness. For diagnosis, an extensive differential diagnostic workup is required and the evaluation of clinical ME/CFS criteria. ME/CFS following COVID-19 has been reported in adults but not in pediatric patients younger than 19 years of age. What is newWe present novel questionnairs (MBSQs), as tools to assess common ME/CFS case definitions in pediatric and adult patients with post-COVID-19 condition and beyond. We report on ten patients aged 11 to 25 years diagnosed with ME/CFS following asymptomatic SARS-CoV-2 infection or mild to moderate COVID-19.

A Scoping Review of Pacing for Management of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): Lessons Learned for the Long COVID Pandemic (preprint)

Background: Controversy over treatment for people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a barrier to appropriate treatment. Energy management or pacing is a prominent coping strategy for people with ME/CFS that involves regulating activity to avoid post exertional malaise (PEM), the worsening of symptoms after an activity. Until now, characteristics of pacing, and the effects on patients symptoms had not been systematically reviewed. This is problematic as the most common approach to pacing, pacing prescription, and the pooled efficacy of pacing was unknown. Collating evidence may help advise those suffering with similar symptoms, including long COVID, as practitioners would be better informed on methodological approaches to adopt, pacing implementation, and expected outcomes. Objectives: In this scoping review of the literature, we aggregated type of, and outcomes of, pacing in people with ME/CFS. Eligibility criteria: Original investigations concerning pacing were considered in participants with ME/CFS. Sources of evidence: Six electronic databases (PubMed, Scholar, ScienceDirect, Scopus, Web of Science and the Cochrane Central Register of Controlled Trials [CENTRAL]) were searched; and websites MEPedia, Action for ME, and ME Action were also searched for grey literature. Methods: A scoping review was conducted. Review selection and characterisation was performed by two independent reviewers using pretested forms. Results: Authors reviewed 177 titles and abstracts, resulting in included 17 studies: three randomised control trials (RCTs); one uncontrolled trial; one interventional case series; one retrospective observational study; two prospective observational studies; four cross-sectional observational studies; and five cross-sectional analytical studies. Studies included variable designs, durations, and outcome measures. In terms of pacing administration, studies used educational sessions and diaries for activity monitoring. Eleven studies reported benefits of pacing, four studies reported no effect, and two studies reported a detrimental effect in comparison to the control group. Conclusions: Highly variable study designs and outcome measures, allied to poor to fair methodological quality resulted in heterogenous findings and highlights the requirement for more research examining pacing. Looking to the long COVID pandemic, future studies should be RCTs utilising objectively quantified digitised pacing, over a longer duration of examination, using the core outcome set for patient reported outcome measures.

Reactivation of herpesvirus type-6 and IgA/IgM-mediated responses to activin-A underpin Long COVID, including affective symptoms and chronic fatigue syndrome. (preprint)

Background: Persistent infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), reactivation of dormant viruses, and immune-oxidative responses are involved in Long COVID. Objectives: To investigate whether Long COVID and depressive, anxiety and chronic fatigue syndrome (CFS) symptoms, are associated with IgA/IgM/IgG to SARS-CoV-2, human Herpesvirus type 6 (HHV-6), Epstein-Barr Virus (EBV), and immune-oxidative biomarkers. Methods: We examined 90 Long COVID patients and 90 healthy controls. We measured serum IgA/IgM/IgG against HHV-6 and EBV and their deoxyuridine 5'-triphosphate nucleotidohydrolase (duTPase), SARS-CoV-2, and activin-A, C-reactive protein (CRP), advanced oxidation protein products (AOPP), and insulin resistance (HOMA2-IR). Results: Long COVID patients showed significant elevations in IgG/IgM-SARS-CoV-2, IgG/IgM-HHV-6 and HHV-6-duTPase, IgA/IgM-activin-A, CRP, AOPP, and HOMA2-IR. Neural network analysis yielded a highly significant predictive accuracy of 80.6% for the Long COVID diagnosis (sensitivity: 78.9%, specificity: 81.8%, area under the ROC curve=0.876); the topmost predictors were: IGA-activin-A, IgG-HHV-6, IgM-HHV-6-duTPase, IgG-SARS-CoV-2, and IgM-HHV-6 (all positively) and a factor extracted from all IgA levels to all viral antigens (inversely). The top-5 predictors of affective symptoms due to Long COVID were: IgM-HHV-6-duTPase, IgG-HHV-6, CRP, education, IgA-activin-A (predictive accuracy of r=0.636). The top-5 predictors of CFS due to Long COVID were in descending order: CRP, IgG-HHV-6-duTPase, IgM-activin-A, IgM-SARS-CoV-2, and IgA-activin-A (predictive accuracy: r=0.709). Conclusion: Reactivation of HHV-6, SARS-CoV-2 persistence, and autoimmune reactions to activin-A combined with activated immune-oxidative pathways play a major role in the pathophysiology of Long COVID as well as the severity of affective symptoms and CFS due to Long COVID.

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

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.

The Role of Hypothalamic Phospholipid Liposomes in the Supportive Therapy of Some Manifestations of Long Covid: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and Brain Fog (preprint)

Long Covid is a heterogeneous clinical condition in which Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and brain fog stand out among the different clinical symptoms and syndromes. The cerebral metabolic alterations and neuroendocrine disorders seem to constitute an important part of Long Covid. Given the substantial lack of drugs and effective therapeutic strategies, hypothalamic phospholipid liposomes which have been on the market for several years as adjuvant therapy of cerebral metabolic alterations resulting from neuroendocrine disorders, can be taken into consideration in an overall therapeutic strategy that aims to control the Long Covid associated symptoms and syndromes. Their pharmacological mechanisms and clinical effects strongly support their usefulness in Long Covid. Our initial clinical experience corroborates this rationale. Further research is imperative in order to obtain robust clinical evidence.

Polymerized type I collagen down-regulates STAT-1 phosphorylation through engagement to LAIR-1 in M1-macrophages avoiding long COVID (preprint)

Background: The polymerized type I collagen (PTIC) is a g-irradiated mixture of pepsinized porcine type I collagen and polyvinylpyrrolidone (PVP). It has immunomodulatory properties. However, the receptor and signaling pathway through which it exerts its therapeutic effects has not yet been identified. Aim: To evaluate LAIR-1 as a potential receptor for PTIC and the signaling pathway evoked by ligand-receptor binding. Methods: LAIR-1 binding assay was performed by incubating various concentrations of recombinant human LAIR-1 with native type I collagen or PTIC. Macrophages M1-derived from THP-1 cells were cultured with 2-10% PTIC for 24 h. Cell lysates from THP-1, monocytes-like cells (MLCs), M1, M1+IFN-{gamma}, M1+LPS, and 2 or 10% PTIC treated M1 were analyzed by western blot for the transcription factors NF-{kappa}B (p65), p38, STAT-1, and pSTAT-1. Cytokines, Th1 cells, and M1/M2 macrophages were analyzed by luminometry and flow cytometry from blood samples of symptomatic COVID-19 outpatients on treatment with intramuscular administration of PTIC. Results: PTIC binds LAIR-1 with a similar affinity to native collagen. This binding decreases STAT-1 signaling IFN-{gamma}-induced and IL-1{beta} expression in M1 macrophages by down-regulating STAT-1 phosphorylation. Moreover, intramuscular PTIC treatment of symptomatic COVID-19 outpatients decreased at statistically significant levels the percentage of M1 macrophages and cytokines (IP-10, MIF, eotaxin, IL-8, IL-1RA, and M-CSF) associated with STAT-1 transcription factor and increased M2 macrophages and Th1 cells. The downregulation of inflammatory mediators was related to better oxygen saturation and decreased dyspnea, chest pain, cough, and chronic fatigue syndrome in the acute phase of infection and the long term. Conclusion: PTIC is an agonist of LAIR-1 and down-regulates STAT-1 phosphorylation. PTIC could be relevant for treating STAT-1-mediated inflammatory diseases, including COVID-19 and long COVID.

Pre-pandemic activity on a myalgic encephalomyelitis/chronic fatigue syndrome support forum is highly associated with later activity on a long COVID support forum for a variety of reasons: a mixed methods study. (preprint)

Encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID share some clinical and social characteristics. We predicted that this would lead to an increased interaction between pre-pandemic members of a ME/CFS online support community and a long COVID community. We performed a mixed-methods retrospective observational study of the Reddit activity of 7,544 users active on Reddit's long COVID forum. From among 1600 forums, pre-pandemic activity specifically on a ME/CFS forum is the top predictor of later participation on the long COVID forum versus an acute COVID support forum. In the qualitative portion, motives for this co-participation included seeking mutual support and dual identification with both conditions. Some of this effect may be explained by pre-existing ME/CFS possibly being a risk factor for long COVID and/or SARS-CoV-2 infection being a cause of ME/CFS relapse. The high rate of ME/CFS patients seeking mutual support on a long COVID forum speaks to the long-suffering experience of these patients not feeling heard or respected, and the hope of some ME/CFS patients to gain legitimacy through the public's growing recognition of long COVID.

Increased circulating fibronectin, depletion of natural IgM and heightened EBV, HSV-1 reactivation in ME/CFS and long COVID (preprint)

Myalgic Encephalomyelitis/ Chronic Fatigue syndrome (ME/CFS) is a complex, debilitating, long-term illness without a diagnostic biomarker. ME/CFS patients share overlapping symptoms with long COVID patients, an observation which has strengthened the infectious origin hypothesis of ME/CFS. However, the exact sequence of events leading to disease development is largely unknown for both clinical conditions. Here we show antibody response to herpesvirus dUTPases, particularly to that of Epstein-Barr virus (EBV) and HSV-1, increased circulating fibronectin (FN1) levels in serum and depletion of natural IgM against fibronectin ((n)IgM-FN1) are common factors for both severe ME/CFS and long COVID. We provide evidence for herpesvirus dUTPases-mediated alterations in host cell cytoskeleton, mitochondrial dysfunction and OXPHOS. Our data show altered active immune complexes, immunoglobulin-mediated mitochondrial fragmentation as well as adaptive IgM production in ME/CFS patients. Our findings provide mechanistic insight into both ME/CFS and long COVID development. Finding of increased circulating FN1 and depletion of (n)IgM-FN1 as a biomarker for the severity of both ME/CFS and long COVID has an immediate implication in diagnostics and development of treatment modalities.

Clinical Features and Short-Term Outcomes in Virus-Induced Bradycardia: Comparison Between Covid and non-Covid Infected Patients (preprint)

Covid-19 outbreak has drawn attention to the fact that viral infections might present with clinical bradycardia. Seeking its clinical significance, not yet unveiled by the literature, we come across other viral infections that also show clinical bradycardia during its clinical course, such as dengue fever and viral diarrhea. The clinical presentation of the latest seems to be severe, often presenting with orthostatic intolerance and fatigue symptoms, requiring expert consultation irrespective of the infection stage, and in case of dengue fever, frequently during the recovery phase. Meanwhile, in Covid-19 infected patients, the bradycardia observed is mild, frugal, and usually asymptomatic. Thus, we conducted a comparison between two different groups of patients with viral infection displaying clinical bradycardia during hospital stay: Covid and non-Covid patients regarding clinical and Holter monitoring parameters. All patients had other causes of bradycardia excluded and echocardiography and cardiac biomarkers ruled out acute myocarditis. The results showed that non-Covid patients presented with significantly lower mean and minimum heart rates (HR) on Holter monitoring, as well as longer times in with HR < 50 beats per minute (bpm).  SDNN and pNN>50% were also significantly higher in non-Covid patients. The minimum systolic BP was significantly lower in non-Covid patients. The study shows that Covid-19 is not the only viral infection that may display with clinical bradycardia, but it’s much milder than other viral infections such as dengue fever and viral diarrhea. It remains unclear the mechanism throughout Covid-related bradycardia comes about.

Major Depressive Disorder and Chronic Fatigue Syndrome Show Characteristic Heart Rate Variability Profiles Reflecting Autonomic Dysregulations: Differentiation by Linear Discriminant Analysis.

Major depressive disorder (MDD) and chronic fatigue syndrome (CFS) have overlapping symptoms, and differentiation is important to administer the proper treatment. The present study aimed to assess the usefulness of heart rate variability (HRV) indices. Frequency-domain HRV indices, including high-frequency (HF) and low-frequency (LF) components, their sum (LF+HF), and their ratio (LF/HF), were measured in a three-behavioral-state paradigm composed of initial rest (Rest), task load (Task), and post-task rest (After) periods to examine autonomic regulation. It was found that HF was low at Rest in both disorders, but was lower in MDD than in CFS. LF and LF+HF at Rest were low only in MDD. Attenuated responses of LF, HF, LF+HF, and LF/HF to task load and an excessive increase in HF at After were found in both disorders. The results indicate that an overall HRV reduction at Rest may support a diagnosis of MDD. HF reduction was found in CFS, but with a lesser severity. Response disturbances of HRV to Task were observed in both disorders, and would suggest the presence of CFS when the baseline HRV has not been reduced. Linear discriminant analysis using HRV indices was able to differentiate MDD from CFS, with a sensitivity and specificity of 91.8% and 100%, respectively. HRV indices in MDD and CFS show both common and different profiles, and can be useful for the differential diagnosis.