Tag: long covid pathomechanism

Mechanisms of long COVID: An updated review

Abstract:

The coronavirus disease 2019 (COVID-19) pandemic has been ongoing for more than 3 years, with an enormous impact on global health and economies. In some patients, symptoms and signs may remain after recovery from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which cannot be explained by an alternate diagnosis; this condition has been defined as long COVID.

Long COVID may exist in patients with both mild and severe disease and is prevalent after infection with different SARS-CoV-2 variants. The most common symptoms include fatigue, dyspnea, and other symptoms involving multiple organs. Vaccination results in lower rates of long COVID. To date, the mechanisms of long COVID remain unclear. In this narrative review, we summarized the clinical presentations and current evidence regarding the pathogenesis of long COVID.

Source: Yan Liu, Xiaoying Gu, Haibo Li, Hui Zhang, Jiuyang Xu. Mechanisms of long COVID: An updated review. Chinese Medical Journal Pulmonary and Critical Care Medicine, Volume 1, Issue 4, December 2023, Pages 231-240. https://www.sciencedirect.com/science/article/pii/S2772558823000580 (Full text)

Investigating the Human Intestinal DNA Virome and Predicting Disease-Associated Virus-Host Interactions in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Abstract:

Understanding how the human virome, and which of its constituents, contributes to health or disease states is reliant on obtaining comprehensive virome profiles. By combining DNA viromes from isolated virus-like particles (VLPs) and whole metagenomes from the same faecal sample of a small cohort of healthy individuals and patients with severe myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), we have obtained a more inclusive profile of the human intestinal DNA virome.

Key features are the identification of a core virome comprising tailed phages of the class Caudoviricetes, and a greater diversity of DNA viruses including extracellular phages and integrated prophages. Using an in silico approach, we predicted interactions between members of the Anaerotruncus genus and unique viruses present in ME/CFS microbiomes. This study therefore provides a framework and rationale for studies of larger cohorts of patients to further investigate disease-associated interactions between the intestinal virome and the bacteriome.

Source: Hsieh SY, Savva GM, Telatin A, Tiwari SK, Tariq MA, Newberry F, Seton KA, Booth C, Bansal AS, Wileman T, Adriaenssens EM, Carding SR. Investigating the Human Intestinal DNA Virome and Predicting Disease-Associated Virus-Host Interactions in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Int J Mol Sci. 2023 Dec 8;24(24):17267. doi: 10.3390/ijms242417267. PMID: 38139096. https://www.mdpi.com/1422-0067/24/24/17267 (Full text)

Molecular Mechanisms Involved in the Occurrence and Progression of Long COVID and Associated Analysis Techniques

Abstract:

Long COVID, also known as post-acute sequelae of SARS-CoV-2 infection (PASC), has emerged as a significant health concern following the COVID-19 pandemic. Molecular mechanisms underlying the occurrence and progression of long COVID include viral persistence, immune dysregulation, endothelial dysfunction, and neurological involvement, and highlight the need for further research to develop targeted therapies for this condition.
While a clearer picture of the clinical symptomatology is shaping, many molecular mechanisms are yet to be unraveled, given their complexity and high level of interaction with other metabolic pathways. This review summarizes some of the most important symptoms and associated molecular mechanisms that occur in long COVID, as well as the most relevant molecular techniques that can be used in understanding the viral pathogen, its affinity towards the host and the possible outcomes of host-pathogen interaction.
Source: Constantinescu-Bercu, A.; Lobiuc, A.; Caliman Sturdza, O.A.; Oita, R.; Iavorschi, M.; Paval, N.; Soldanescu, I.; Dimian, M.; Covasa, M. Molecular Mechanisms Involved in the Occurrence and Progression of Long COVID and Associated Analysis Techniques. Preprints 2023, 2023111865. https://doi.org/10.20944/preprints202311.1865.v1 https://www.preprints.org/manuscript/202311.1865/v1 (Full text available as PDF file)

Beyond the acute illness: Exploring long COVID and its impact on multiple organ systems

Abstract:

Unprecedented worldwide health catastrophe due to the COVID-19 pandemic has ended up resulting in high morbidity and mortality rates. Even though many people recover from acute infection, there is rising concern regarding post-COVID-19 conditions (PCCs), often referred to as post-acute sequelae of SARS-CoV-2 infection (PASC) or “long COVID.”

The respiratory, cardiovascular, neurological, and endocrine systems are just a few of the many organ systems that can be impacted by this multifarious, complicated illness. The clinical manifestations of long COVID can vary among individuals and may include fatigue, dyspnea, chest pain, cognitive impairment, and new-onset diabetes, among others.

Although the underlying processes of long COVID are not fully understood, they probably involve unregulated immune response, persistent generation of pro-inflammatory cytokines (chronic inflammation), autoimmune-like reactions, persistent viral replication, and micro-clot formation.

To create successful treatments and care plans, it is essential to comprehend the immunological mechanisms causing these difficulties. The pathogenesis of long COVID should be clarified and potential biomarkers to help with diagnosis and treatment should be sought after. To reduce the burden of long COVID on people and healthcare systems around the world, the need for long-term monitoring and management of long COVID problems should be emphasized. It also underscores the significance of a multidisciplinary approach to patient care. The goal of this review is to carefully evaluate the clinical signs and symptoms of long COVID, their underlying causes, and any potential immunological implications.

Source: Bhattacharjee N, Sarkar P, Sarkar T. Beyond the acute illness: Exploring long COVID and its impact on multiple organ systems. Physiol Int. 2023 Nov 9. doi: 10.1556/2060.2023.00256. Epub ahead of print. PMID: 37943302. https://akjournals.com/view/journals/2060/aop/article-10.1556-2060.2023.00256/article-10.1556-2060.2023.00256.xml (Full text)

Several De-Regulated Chemokine Pathways Characterize Long COVID Syndrome

Abstract:

Introduction: The diagnosis of the Long COVID multi-organ syndrome is impeded by lack of circulating biomarkers. Hypothesis: We hypothesized, that post-COVID syndrome is associated with circulating protein de-regulation, enabling diagnosis of long COVID syndrome.

Methods: Consecutive patients (70% female, 55±8y) with long COVID syndrome (n=70, 64.3% female, 49±6y) and non-diseased, non-vaccinated healthy controls (n=23, 70% female, 55±8y) of the Vienna POSTCOV Registry (EC 1008/2021) were included, and blood samples were collected. Proteomics was performed by using the Olink proteomics technology (Olink Proteomics, Uppsala, Sweden), by using cardiovascular, Immunologic, inflammation and neurologic protein (3×96 protein) panels. Protein-protein interaction network were built by selecting the significantly dysregulated proteins from the 4 panels, and were classified into functional groups.

Results: Multiplex protein panel revealed 34 significantly de-regulated proteins as compared to controls. Gene ontology categorized the 29 upregulated proteins into several pathways with significant (false discovery rate <0.05) functional enrichment in biological processes (eg. death-inducing signaling complex assembly or positive regulation of tumor necrosis factor-mediated signaling pathway), and in molecular function (catalytic activity). Downregulated proteins were in association with chemokine-mediated signaling pathway and chemokine activity (Figure). KEGG pathway analyses revealed upregulated apoptosis, TNF- and NF-κB signaling pathways, but unchanged ACE2 receptors in patients with long COVID syndrome.

Conclusions: Several de-regulated chemokine pathways characterize long COVID syndrome and may serve as a combined biomarker panel for long COVOD diagnosis and target drug prediction.

Source: Mariann Gyongyosi, Emilie Han, Dominika Lukovic, Kevin Hamzaraj, Jutta K Bergler-Klein and Ena Hasimbegovic. Several De-Regulated Chemokine Pathways Characterize Long COVID Syndrome. Originally published 6 Nov 2023,Circulation. 2023;148:A18340 https://www.ahajournals.org/doi/abs/10.1161/circ.148.suppl_1.18340

Dysregulations in hemostasis, metabolism, immune response, and angiogenesis in post-acute COVID-19 syndrome with and without postural orthostatic tachycardia syndrome: a multi-omic profiling study

Abstract:

Post-acute COVID-19 (PACS) are associated with cardiovascular dysfunction, especially postural orthostatic tachycardia syndrome (POTS). Patients with PACS, both in the absence or presence of POTS, exhibit a wide range of persisting symptoms long after the acute infection. Some of these symptoms may stem from alterations in cardiovascular homeostasis, but the exact mechanisms are poorly understood.

The aim of this study was to provide a broad molecular characterization of patients with PACS with (PACS + POTS) and without (PACS-POTS) POTS compared to healthy subjects, including a broad proteomic characterization with a focus on plasma cardiometabolic proteins, quantification of cytokines/chemokines and determination of plasma sphingolipid levels.

Twenty-one healthy subjects without a prior COVID-19 infection (mean age 43 years, 95% females), 20 non-hospitalized patients with PACS + POTS (mean age 39 years, 95% females) and 22 non-hospitalized patients with PACS-POTS (mean age 44 years, 100% females) were studied. PACS patients were non-hospitalized and recruited ≈18 months after the acute infection.

Cardiometabolic proteomic analyses revealed a dysregulation of ≈200 out of 700 analyzed proteins in both PACS groups vs. healthy subjects with the majority (> 90%) being upregulated. There was a large overlap (> 90%) with no major differences between the PACS groups. Gene ontology enrichment analysis revealed alterations in hemostasis/coagulation, metabolism, immune responses, and angiogenesis in PACS vs. healthy controls.

Furthermore, 11 out of 33 cytokines/chemokines were significantly upregulated both in PACS + POTS and PACS-POTS vs. healthy controls and none of the cytokines were downregulated. There were no differences in between the PACS groups in the cytokine levels. Lastly, 16 and 19 out of 88 sphingolipids were significantly dysregulated in PACS + POTS and PACS-POTS, respectively, compared to controls with no differences between the groups.

Collectively, these observations suggest a clear and distinct dysregulation in the proteome, cytokines/chemokines, and sphingolipid levels in PACS patients compared to healthy subjects without any clear signature associated with POTS. This enhances our understanding and might pave the way for future experimental and clinical investigations to elucidate and/or target resolution of inflammation and micro-clots and restore the hemostasis and immunity in PACS.

Source: Mahdi, A., Zhao, A., Fredengren, E. et al. Dysregulations in hemostasis, metabolism, immune response, and angiogenesis in post-acute COVID-19 syndrome with and without postural orthostatic tachycardia syndrome: a multi-omic profiling study. Sci Rep 13, 20230 (2023). https://doi.org/10.1038/s41598-023-47539-1 https://www.nature.com/articles/s41598-023-47539-1 (Full study)

From aging to long COVID: exploring the convergence of immunosenescence, inflammaging, and autoimmunity

Abstract:

The process of aging is accompanied by a dynamic restructuring of the immune response, a phenomenon known as immunosenescence. This mini-review navigates through the complex landscape of age-associated immune changes, chronic inflammation, age-related autoimmune tendencies, and their potential links with immunopathology of Long COVID. Immunosenescence serves as an introductory departure point, elucidating alterations in immune cell profiles and their functional dynamics, changes in T-cell receptor signaling, cytokine network dysregulation, and compromised regulatory T-cell function.

Subsequent scrutiny of chronic inflammation, or “inflammaging,” highlights its roles in age-related autoimmune susceptibilities and its potential as a mediator of the immune perturbations observed in Long COVID patients. The introduction of epigenetic facets further amplifies the potential interconnections.

In this compact review, we consider the dynamic interactions between immunosenescence, inflammation, and autoimmunity. We aim to explore the multifaceted relationships that link these processes and shed light on the underlying mechanisms that drive their interconnectedness. With a focus on understanding the immunological changes in the context of aging, we seek to provide insights into how immunosenescence and inflammation contribute to the emergence and progression of autoimmune disorders in the elderly and may serve as potential mediator for Long COVID disturbances.

Source: Müller L, Di Benedetto S. From aging to long COVID: exploring the convergence of immunosenescence, inflammaging, and autoimmunity. Front Immunol. 2023 Oct 24;14:1298004. doi: 10.3389/fimmu.2023.1298004. PMID: 37942323; PMCID: PMC10628127. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10628127/ (Full text)

Probing long COVID through a proteomic lens: a comprehensive two-year longitudinal cohort study of hospitalised survivors

Abstract:

Background: As a debilitating condition that can impact a whole spectrum of people and involve multi-organ systems, long COVID has aroused the most attention than ever. However, mechanisms of long COVID are not clearly understood, and underlying biomarkers that can affect the long-term consequences of COVID-19 are paramount to be identified.

Methods: Participants for the current study were from a cohort study of COVID-19 survivors discharged from hospital between Jan 7, and May 29, 2020. We profiled the proteomic of plasma samples from hospitalised COVID-19 survivors at 6-month, 1-year, and 2-year after symptom onset and age and sex matched healthy controls. Fold-change of >2 or <0.5, and false-discovery rate adjusted P value of 0.05 were used to filter differentially expressed proteins (DEPs). In-genuity pathway analysis was performed to explore the down-stream effects in the dataset of significantly up- or down-regulated proteins. Proteins were integrated with long-term consequences of COVID-19 survivors to explore potential biomarkers of long COVID.

Findings: The proteomic of 709 plasma samples from 181 COVID-19 survivors and 181 matched healthy controls was profiled. In both COVID-19 and control group, 114 (63%) were male. The results indicated four major recovery modes of biological processes. Pathways related to cell-matrix interactions and cytoskeletal remodeling and hypertrophic cardiomyopathy and dilated cardiomyopathy pathways recovered relatively earlier which was before 1-year after infection. Majority of immune response pathways, complement and coagulation cascade, and cholesterol metabolism returned to similar status of matched healthy controls later but before 2-year after infection. Fc receptor signaling pathway still did not return to status similar to healthy controls at 2-year follow-up. Pathways related to neuron generation and differentiation showed persistent suppression across 2-year after infection. Among 98 DEPs from the above pathways, evidence was found for association of 11 proteins with lung function recovery, with the associations consistent at two consecutive or all three follow-ups. These proteins were mainly enriched in complement and coagulation (COMP, PLG, SERPINE1, SRGN, COL1A1, FLNA, and APOE) and hypertrophic/dilated cardiomyopathy (TPM2, TPM1, and AGT) pathways. Two DEPs (APOA4 and LRP1) involved in both neuron and cholesterol pathways showed associations with smell disorder.

Interpretation: The study findings provided molecular insights into potential mechanism of long COVID, and put forward biomarkers for more precise intervention to reduce burden of long COVID.

Source: Gu X, Wang S, Zhang W, Li C, Guo L, Wang Z, Li H, Zhang H, Zhou Y, Liang W, Li H, Liu Y, Wang Y, Huang L, Dong T, Zhang D, Wong CCL, Cao B. Probing long COVID through a proteomic lens: a comprehensive two-year longitudinal cohort study of hospitalised survivors. EBioMedicine. 2023 Nov 2;98:104851. doi: 10.1016/j.ebiom.2023.104851. Epub ahead of print. PMID: 37924708. https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(23)00417-6/fulltext (Full text)

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

Abstract:

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, α+β-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.

Source: Abbas F. Almulla, Michael Maes, Bo Zhou, Hussein K. Al-Hakeim, Aristo Vojdani. Brain-targeted autoimmunity is strongly associated with Long COVID and its chronic fatigue syndrome as well as its affective symptoms. medRxiv [Preprint] https://www.medrxiv.org/content/10.1101/2023.10.04.23296554v1 (Full text available as PDF file)

Blood T cell phenotypes correlate with fatigue severity in post-acute sequelae of COVID-19

Abstract:

Purpose: Post-acute sequelae of COVID-19 (PASC) affect approximately 10% of convalescent patients. The spectrum of symptoms is broad and heterogeneous with fatigue being the most often reported sequela. Easily accessible blood biomarkers to determine PASC severity are lacking. Thus, our study aimed to correlate immune phenotypes with PASC across the severity spectrum of COVID-19.

Methods: A total of 176 originally immunonaïve, convalescent COVID-19 patients from a prospective cohort during the first pandemic phase were stratified by initial disease severity and underwent clinical, psychosocial, and immune phenotyping around 10 weeks after first COVID-19 symptoms. COVID-19-associated fatigue dynamics were assessed and related to clinical and immune phenotypes.

Results: Fatigue and severe fatigue were commonly reported irrespective of initial COVID-19 severity or organ-specific PASC. A clinically relevant increase in fatigue severity after COVID-19 was detected in all groups. Neutralizing antibody titers were higher in patients with severe acute disease, but no association was found between antibody titers and PASC. While absolute peripheral blood immune cell counts in originally immunonaïve PASC patients did not differ from unexposed controls, peripheral CD3+CD4+ T cell counts were independently correlated with fatigue severity across all strata in multivariable analysis.

Conclusions: Patients were at similar risk of self-reported PASC irrespective of initial disease severity. The independent correlation between fatigue severity and blood T cell phenotypes indicates a possible role of CD4+ T cells in the pathogenesis of post-COVID-19 fatigue, which might serve as a blood biomarker.

Source: Pink, I., Hennigs, J.K., Ruhl, L. et al. Blood T cell phenotypes correlate with fatigue severity in post-acute sequelae of COVID-19. Infection (2023). https://doi.org/10.1007/s15010-023-02114-8 https://link.springer.com/article/10.1007/s15010-023-02114-8 (Full text)