Investigating the possible mechanisms of autonomic dysfunction post-COVID-19

Abstract:

Patients with long COVID suffer from many neurological manifestations that persist for 3 months following infection by SARS-CoV-2. Autonomic dysfunction (AD) or dysautonomia is one complication of long COVID that causes patients to experience fatigue, dizziness, syncope, dyspnea, orthostatic intolerance, nausea, vomiting, and heart palpitations. The pathophysiology behind AD onset post-COVID is largely unknown. As such, this review aims to highlight the potential mechanisms by which AD occurs in patients with long COVID.

The first proposed mechanism includes the direct invasion of the hypothalamus or the medulla by SARS-CoV-2. Entry to these autonomic centers may occur through the neuronal or hematogenous routes. However, evidence so far indicates that neurological manifestations such as AD are caused indirectly.

Another mechanism is autoimmunity whereby autoantibodies against different receptors and glycoproteins expressed on cellular membranes are produced. Additionally, persistent inflammation and hypoxia can work separately or together to promote sympathetic overactivation in a bidirectional interaction. Renin-angiotensin system imbalance can also drive AD in long COVID through the downregulation of relevant receptors and formation of autoantibodies. Understanding the pathophysiology of AD post-COVID-19 may help provide early diagnosis and better therapy for patients.

Source: Jammoul M, Naddour J, Madi A, Reslan MA, Hatoum F, Zeineddine J, Abou-Kheir W, Lawand N. Investigating the possible mechanisms of autonomic dysfunction post-COVID-19. Auton Neurosci. 2022 Dec 24;245:103071. doi: 10.1016/j.autneu.2022.103071. Epub ahead of print. PMID: 36580747; PMCID: PMC9789535. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9789535/ (Full text)

Long Covid: Untangling the Complex Syndrome and the Search for Therapeutics

Abstract:

Long Covid can affect anyone who has previously had acute COVID-19. The root causes of this syndrome are still unknown, and no effective therapeutics are available. This complex syndrome, with a wide array of symptoms, is still evolving. Given the dire situation, it is important to identify the causes of Long Covid and the changes occurring within the immune system of affected patients to figure out how to treat it.
The immune system intersects with the persistent viral fragments and blood clots that are implicated in this syndrome; understanding how these complex systems interact may help in untangling the puzzling physiopathology of Long Covid and identifying mitigation measures to provide patients some relief. In this paper, we discuss evidence-based findings and formulate hypotheses on the mechanisms underlying Long Covid’s physiopathology and propose potential therapeutic options.
Source: Haque A, Pant AB. Long Covid: Untangling the Complex Syndrome and the Search for Therapeutics. Viruses. 2023; 15(1):42. https://doi.org/10.3390/v15010042 https://www.mdpi.com/1999-4915/15/1/42 (Full text)

Deep Dive into the Long Haul: Analysis of Symptom Clusters and Risk Factors for Post-Acute Sequelae of COVID-19 to Inform Clinical Care

Abstract:

Long COVID is a chronic condition characterized by symptoms such as fatigue, dyspnea, and cognitive impairment that persist or relapse months after an acute infection with the SARS-CoV-2 virus. Many distinct symptoms have been attributed to Long COVID; however, little is known about the potential clustering of these symptoms and risk factors that may predispose patients to certain clusters. In this study, an electronic survey was sent to patients in the UC San Diego Health (UCSDH) system who tested positive for COVID-19, querying if patients were experiencing symptoms consistent with Long COVID.

Based on survey results, along with patient demographics reported in the electronic health record (EHR), linear and logistic regression models were used to examine putative risk factors, and exploratory factor analysis was performed to determine symptom clusters. Among 999 survey respondents, increased odds of Long COVID (n = 421; 42%) and greater Long COVID symptom burden were associated with female sex (OR = 1.73, 99% CI: 1.16-2.58; β = 0.48, 0.22-0.75), COVID-19 hospitalization (OR = 4.51, 2.50-8.43; β = 0.48, 0.17-0.78), and poorer pre-COVID self-rated health (OR = 0.75, 0.57-0.97; β = -0.19, -0.32–0.07).

Over one-fifth of Long COVID patients screened positive for depression and/or anxiety, the latter of which was associated with younger age (OR = 0.96, 0.94-0.99). Factor analysis of 16 self-reported symptoms suggested five symptom clusters-gastrointestinal (GI), musculoskeletal (MSK), neurocognitive (NC), airway (AW), and cardiopulmonary (CP), with older age (β = 0.21, 0.11-0.30) and mixed race (β = 0.27, 0.04-0.51) being associated with greater MSK symptom burden. Greater NC symptom burden was associated with increased odds of depression (OR = 5.86, 2.71-13.8) and anxiety (OR = 2.83, 1.36-6.14).

These results can inform clinicians in identifying patients at increased risk for Long COVID-related medical issues, particularly neurocognitive symptoms and symptom clusters, as well as informing health systems to manage operational expectations on a population-health level.

Source: Goldhaber NH, Kohn JN, Ogan WS, Sitapati A, Longhurst CA, Wang A, Lee S, Hong S, Horton LE. Deep Dive into the Long Haul: Analysis of Symptom Clusters and Risk Factors for Post-Acute Sequelae of COVID-19 to Inform Clinical Care. Int J Environ Res Public Health. 2022 Dec 15;19(24):16841. doi: 10.3390/ijerph192416841. PMID: 36554723; PMCID: PMC9778884. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9778884/ (Full text)

Low molecular weight cytotoxic components (DAMPs) form the post-COVID-19 syndrome

Abstract:

We studied the role of cytotoxic components (DAMPs) formed in the body of patients with COVID-19 in ensuring the long-term preservation of post-COVID-19 manifestations and the possibility of creating an experimental model by transferring DAMPs to rats. In patients with post-COVID-19 syndrome (PCS) 2 months after SARS-CoV-2 infection we determined the presence of cytotoxic components in the blood serum (Terasaki test, Dunaliella viridis test and content of DAMPs).

In post-COVID-19 syndrome patients with a high content of serum cytotoxic oligopeptide fraction (selective group, n = 16) we determined the number of leukocytes, lymphocytes, neutrophil granulocytes and monocytes in the blood, the content of C-reactive protein (CRP), the concentration of C3 and C4 complement components and circulating immune complexes, the serum content of IL-6, IL -10, IL-18, TNF-α, phagocytic activity of neutrophils, presence of neutrophil traps and autoantibodies ANA.

It has been shown that in patients with PCS, there are components with cytotoxicity in the blood serum, form specific immunopathological patterns, which are characterized by: an increased content of CRP, complement system components C3 and C4 and cytokines (TNF-α, IL-6, IL-10, IL-18) activation, the formation of a wide range of autoantibodies ANA, the low efficiency of endocytosis in oxygen-independent phagocytosis; their phagocytic activity reaches its functional limit, and against this background, activation of neutrophil traps occurs, which can contribute to further induction of DAMPs. This self-sustaining cell-killing activation provided long-term preservation of PCS symptoms.

The transfer of blood serum components from selective group patients with PCS to rats was accompanied by the appearance of cytotoxic components in them which induced sensitization and immunopathological reactions. Preventive administration of a biologically active substance with polyfunctional properties MF to experimental animals “corrected” the initial functional state of the body’s immune-metabolic system and eliminated or facilitated immuno-inflammatory reactions.

Source: Klimova EM, Bozhkov AI, Lavinska OV, Drozdova LA, Kurhuzova NI. Low molecular weight cytotoxic components (DAMPs) form the post-COVID-19 syndrome. Immunobiology. 2023 Jan;228(1):152316. doi: 10.1016/j.imbio.2022.152316. Epub 2022 Dec 20. PMID: 36565610; PMCID: PMC9764760. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9764760/ (Full text)

Generalisable long COVID subtypes: Findings from the NIH N3C and RECOVER programmes

Abstract:

Background: Stratification of patients with post-acute sequelae of SARS-CoV-2 infection (PASC, or long COVID) would allow precision clinical management strategies. However, long COVID is incompletely understood and characterised by a wide range of manifestations that are difficult to analyse computationally. Additionally, the generalisability of machine learning classification of COVID-19 clinical outcomes has rarely been tested.

Methods: We present a method for computationally modelling PASC phenotype data based on electronic healthcare records (EHRs) and for assessing pairwise phenotypic similarity between patients using semantic similarity. Our approach defines a nonlinear similarity function that maps from a feature space of phenotypic abnormalities to a matrix of pairwise patient similarity that can be clustered using unsupervised machine learning.

Findings: We found six clusters of PASC patients, each with distinct profiles of phenotypic abnormalities, including clusters with distinct pulmonary, neuropsychiatric, and cardiovascular abnormalities, and a cluster associated with broad, severe manifestations and increased mortality. There was significant association of cluster membership with a range of pre-existing conditions and measures of severity during acute COVID-19. We assigned new patients from other healthcare centres to clusters by maximum semantic similarity to the original patients, and showed that the clusters were generalisable across different hospital systems. The increased mortality rate originally identified in one cluster was consistently observed in patients assigned to that cluster in other hospital systems.

Interpretation: Semantic phenotypic clustering provides a foundation for assigning patients to stratified subgroups for natural history or therapy studies on PASC.

Source: Reese JT, Blau H, Casiraghi E, Bergquist T, Loomba JJ, Callahan TJ, Laraway B, Antonescu C, Coleman B, Gargano M, Wilkins KJ, Cappelletti L, Fontana T, Ammar N, Antony B, Murali TM, Caufield JH, Karlebach G, McMurry JA, Williams A, Moffitt R, Banerjee J, Solomonides AE, Davis H, Kostka K, Valentini G, Sahner D, Chute CG, Madlock-Brown C, Haendel MA, Robinson PN; N3C Consortium; RECOVER Consortium. Generalisable long COVID subtypes: Findings from the NIH N3C and RECOVER programmes. EBioMedicine. 2022 Dec 21;87:104413. doi: 10.1016/j.ebiom.2022.104413. Epub ahead of print. PMID: 36563487; PMCID: PMC9769411. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9769411/ (Full text)

Characteristics and predictors of Long COVID among diagnosed cases of COVID-19

Abstract:

Background: Long COVID or long-term symptoms after COVID-19 has the ability to affect health and quality of life. Knowledge about the burden and predictors could aid in their prevention and management. Most of the studies are from high-income countries and focus on severe acute COVID-19 cases. We did this study to estimate the incidence and identify the characteristics and predictors of Long COVID among our patients.

Methodology: We recruited adult (≥18 years) patients who were diagnosed as Reverse Transcription Polymerase Chain Reaction (RTPCR) confirmed SARS-COV-2 infection and were either hospitalized or tested on outpatient basis. Eligible participants were followed up telephonically after four weeks and six months of diagnosis of SARS-COV-2 infection to collect data on sociodemographic, clinical history, vaccination history, Cycle threshold (Ct) values during diagnosis and other variables. Characteristics of Long COVID were elicited, and multivariable logistic regression was done to find the predictors of Long COVID.

Results: We have analyzed 487 and 371 individual data with a median follow-up of 44 days (Inter quartile range (IQR): 39,47) and 223 days (IQR:195,251), respectively. Overall, Long COVID was reported by 29.2% (95% Confidence interval (CI): 25.3%,33.4%) and 9.4% (95% CI: 6.7%,12.9%) of participants at four weeks and six months of follow-up, respectively. Incidence of Long COVID among patients with mild/moderate disease (n = 415) was 23.4% (95% CI: 19.5%,27.7%) as compared to 62.5% (95% CI: 50.7%,73%) in severe/critical cases(n = 72) at four weeks of follow-up. At six months, the incidence among mild/moderate (n = 319) was 7.2% (95% CI:4.6%,10.6%) as compared to 23.1% (95% CI:12.5%,36.8%) in severe/critical (n = 52). The most common Long COVID symptom was fatigue. Statistically significant predictors of Long COVID at four weeks of follow-up were-Pre-existing medical conditions (Adjusted Odds ratio (aOR) = 2.00, 95% CI: 1.16,3.44), having a higher number of symptoms during acute phase of COVID-19 disease (aOR = 11.24, 95% CI: 4.00,31.51), two doses of COVID-19 vaccination (aOR = 2.32, 95% CI: 1.17,4.58), the severity of illness (aOR = 5.71, 95% CI: 3.00,10.89) and being admitted to hospital (Odds ratio (OR) = 3.89, 95% CI: 2.49,6.08).

Conclusion: A considerable proportion of COVID-19 cases reported Long COVID symptoms. More research is needed in Long COVID to objectively assess the symptoms and find the biological and radiological markers.

Source: Arjun MC, Singh AK, Pal D, Das K, G A, Venkateshan M, Mishra B, Patro BK, Mohapatra PR, Subba SH. Characteristics and predictors of Long COVID among diagnosed cases of COVID-19. PLoS One. 2022 Dec 20;17(12):e0278825. doi: 10.1371/journal.pone.0278825. PMID: 36538532; PMCID: PMC9767341. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9767341/ (Full text)

Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) in Adolescents: Practical Guidance and Management Challenges

Abstract:

This paper reviews the current understanding of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and whether any treatment strategies have been effective. ME/CFS is a condition of as yet unknown etiology that commonly follows an infective process. It includes a new onset of fatigue (of more than 3-6 month duration and not relieved by rest), post-exertional malaise, cognitive difficulties and unrefreshing sleep, and frequently orthostatic intolerance, somatic symptoms and pain. Long COVID has renewed interest in the condition and stimulated research with findings suggestive of a multisystem neuroimmune disease. There are no definitively effective treatments. Despite earlier recommendations regarding graded exercise therapy and cognitive behavior therapy, the current recommendations are managing symptoms, with lifestyle management and supportive care.

This paper provides an outline of strategies that young people and their families have reported as helpful in managing a chronic illness that impacts their life socially, physically, emotionally, cognitively and educationally. As the illness frequently occurs at a time of rapid developmental changes, reducing these impacts is reported to be as important as managing the physical symptoms. Young people face a mean duration of 5 years illness (range 1-16 years) with a likely residual 20% having significant restrictions after 10 years.

Their feedback has suggested that symptom management, self-management strategies, advocacy and educational liaison have been the most helpful. They value professionals who will listen and take them seriously, and after excluding alternative diagnoses, they explain the diagnosis, are supportive and assist in monitoring their progress. Remaining engaged in education was the best predictor of later functioning. This allowed for social connections, as well as potential independence and fulfilling some aspirations. The need to consider the impact of this chronic illness on all aspects of adolescent development, as part of management, is highlighted.

Source: Rowe K. Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) in Adolescents: Practical Guidance and Management Challenges. Adolesc Health Med Ther. 2023 Jan 4;14:13-26. doi: 10.2147/AHMT.S317314. PMID: 36632532; PMCID: PMC9827635. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9827635/ (Full text)

Anti-Correlated Myelin-Sensitive MRI Levels in Humans Consistent with a Subcortical to Sensorimotor Regulatory Process-Multi-Cohort Multi-Modal Evidence

Abstract:

Differential axonal myelination synchronises signalling over different axon lengths. The consequences of myelination processes described at the cellular level for the regulation of myelination at the macroscopic level are unknown. We analysed multiple cohorts of myelin-sensitive brain MRI. Our aim was to (i) confirm a previous report of anti-correlation between myelination in subcortical and sensorimotor areas in healthy subjects, (ii) and thereby test our hypothesis for a regulatory interaction between them.

We analysed nine image-sets across three different human cohorts using six MRI modalities. Each image-set contained healthy controls (HC) and ME/CFS subjects. Subcortical and Sensorimotor regions of interest (ROI) were optimised for the detection of anti-correlations and the same ROIs were used to test the HC in all image-sets. For each cohort, median MRI values were computed in both regions for each subject and their correlation across the cohort was computed.

We confirmed negative correlations in healthy controls between subcortical and sensorimotor regions in six image-sets: three T1wSE (p = 5 × 10-8, 5 × 10-7, 0.002), T2wSE (p =2 × 10-6), MTC (p = 0.01), and WM volume (p = 0.02). T1/T2 was the exception with a positive correlation (p = 0.01). This myelin regulation study is novel in several aspects: human subjects, cross-sectional design, ROI optimization, spin-echo MRI and reproducible across multiple independent image-sets.

In multiple independent image-sets we confirmed an anti-correlation between subcortical and sensorimotor myelination which supports a previously unreported regulatory interaction. The subcortical region contained the brain’s primary regulatory nuclei. We suggest a mechanism has evolved whereby relatively low subcortical myelination in an individual is compensated by upregulated sensorimotor myelination to maintain adequate sensorimotor performance.

Source: Barnden L, Crouch B, Kwiatek R, Shan Z, Thapaliya K, Staines D, Bhuta S, Del Fante P, Burnet R. Anti-Correlated Myelin-Sensitive MRI Levels in Humans Consistent with a Subcortical to Sensorimotor Regulatory Process-Multi-Cohort Multi-Modal Evidence. Brain Sci. 2022 Dec 9;12(12):1693. doi: 10.3390/brainsci12121693. PMID: 36552153; PMCID: PMC9776387. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9776387/ (Full text)

Nursing Diagnoses of Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Research Protocol for a Qualitative Synthesis

Abstract:

Although previously developed qualitative studies have explored the experience of illness of individuals with myalgic encephalomyelitis/chronic fatigue syndrome, these findings have not been undertaken for the purpose of enabling the identification of nursing care needs in such patients. This study aims to identify NANDA-I nursing diagnoses of adults with myalgic encephalomyelitis/chronic fatigue syndrome based on a qualitative literature review of their experience of illness.

The protocol includes: searches in the electronic databases Medline, Embase, CINAHL, PsycINFO, SCI-EXPANDED, SSCI, SciELO, LILACS, and Cuiden; and manual searches in specialised journals and the references of the included studies. The authors will systematically search qualitative research studies published in databases from 1994 to 2021. Searches are limited to studies in Spanish and English. All stages of the review process will be carried out independently by two reviewers. Any disagreements shall be resolved through joint discussions, involving a third reviewer if necessary.

The findings will be synthesised into a thematic analysis informed by the Domains and Classes of the NANDA-I Classification of Nursing Diagnoses, which will then serve to identify nursing diagnoses. This review will enable nursing professionals to identify the care needs of individuals with myalgic encephalomyelitis/chronic fatigue syndrome by taking into consideration their experience of illness in its entirety.

Source: Oter-Quintana C, Esteban-Hernández J, Cuéllar-Pompa L, Gil-Carballo MC, Brito-Brito PR, Martín-García A, Alcolea-Cosín MT, Martínez-Marcos M, Alameda-Cuesta A. Nursing Diagnoses of Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Research Protocol for a Qualitative Synthesis. Healthcare (Basel). 2022 Dec 10;10(12):2506. doi: 10.3390/healthcare10122506. PMID: 36554030; PMCID: PMC9777975. https://www.mdpi.com/2227-9032/10/12/2506 (Full text)

Long COVID: major findings, mechanisms and recommendations

Abstract:

Long COVID is an often debilitating illness that occurs in at least 10% of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. More than 200 symptoms have been identified with impacts on multiple organ systems. At least 65 million individuals worldwide are estimated to have long COVID, with cases increasing daily. Biomedical research has made substantial progress in identifying various pathophysiological changes and risk factors and in characterizing the illness; further, similarities with other viral-onset illnesses such as myalgic encephalomyelitis/chronic fatigue syndrome and postural orthostatic tachycardia syndrome have laid the groundwork for research in the field.

In this Review, we explore the current literature and highlight key findings, the overlap with other conditions, the variable onset of symptoms, long COVID in children and the impact of vaccinations. Although these key findings are critical to understanding long COVID, current diagnostic and treatment options are insufficient, and clinical trials must be prioritized that address leading hypotheses. Additionally, to strengthen long COVID research, future studies must account for biases and SARS-CoV-2 testing issues, build on viral-onset research, be inclusive of marginalized populations and meaningfully engage patients throughout the research process.

Source: Davis, H.E., McCorkell, L., Vogel, J.M. et al. Long COVID: major findings, mechanisms and recommendations. Nat Rev Microbiol (2023). https://doi.org/10.1038/s41579-022-00846-2 https://www.nature.com/articles/s41579-022-00846-2