Tag: long covid pathomechanism

Pathophysiology and mechanism of long COVID: a comprehensive review

Abstract:

Background: After almost 2 years of fighting against SARS-CoV-2 pandemic, the number of patients enduring persistent symptoms long after acute infection is a matter of concern. This set of symptoms was referred to as “long COVID”, and it was defined more recently as “Post COVID-19 condition” by the World health Organization (WHO). Although studies have revealed that long COVID can manifest whatever the severity of inaugural illness, the underlying pathophysiology is still enigmatic.

Aim: To conduct a comprehensive review to address the putative pathophysiology underlying the persisting symptoms of long COVID.

Method: We searched 11 bibliographic databases (Cochrane Library, JBI EBP Database, Medline, Embase, PsycInfo, CINHAL, Ovid Nursing Database, Journals@Ovid, SciLit, EuropePMC, and CoronaCentral). We selected studies that put forward hypotheses on the pathophysiology, as well as those that encompassed long COVID patients in their research investigation.

Results: A total of 98 articles were included in the systematic review, 54 of which exclusively addressed hypotheses on pathophysiology, while 44 involved COVID patients. Studies that included patients displayed heterogeneity with respect to the severity of initial illness, timing of analysis, or presence of a control group. Although long COVID likely results from long-term organ damage due to acute-phase infection, specific mechanisms following the initial illness could contribute to the later symptoms possibly affecting many organs. As such, autonomic nervous system damage could account for many symptoms without clear evidence of organ damage. Immune dysregulation, auto-immunity, endothelial dysfunction, occult viral persistence, as well as coagulation activation are the main underlying pathophysiological mechanisms so far.

Conclusion: Evidence on why persistent symptoms occur is still limited, and available studies are heterogeneous. Apart from long-term organ damage, many hints suggest that specific mechanisms following acute illness could be involved in long COVID symptoms.

KEY MESSAGES:

  • Long-COVID is a multisystem disease that develops regardless of the initial disease severity. Its clinical spectrum comprises a wide range of symptoms.
  • The mechanisms underlying its pathophysiology are still unclear. Although organ damage from the acute infection phase likely accounts for symptoms, specific long-lasting inflammatory mechanisms have been proposed, as well.
  • Existing studies involving Long-COVID patients are highly heterogeneous, as they include patients with various COVID-19 severity levels and different time frame analysis, as well.

Source: Castanares-Zapatero D, Chalon P, Kohn L, Dauvrin M, Detollenaere J, Maertens de Noordhout C, Primus-de Jong C, Cleemput I, Van den Heede K. Pathophysiology and mechanism of long COVID: a comprehensive review. Ann Med. 2022 Dec;54(1):1473-1487. doi: 10.1080/07853890.2022.2076901. PMID: 35594336; PMCID: PMC9132392. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9132392/ (Full text)

Impaired exercise capacity in post-COVID syndrome: the role of VWF-ADAMTS13 axis

Abstract:

Post-COVID syndrome (PCS) or Long-COVID is an increasingly recognised complication of acute SARS-CoV-2 infection, characterised by persistent fatigue, reduced exercise tolerance chest pain, shortness of breath and cognitive slowing. Acute COVID-19 is strongly linked with increased risk of thrombosis; a prothrombotic state, quantified by elevated Von Willebrand Factor (VWF) Antigen (Ag):ADAMTS13 ratio, and is associated with severity of acute COVID-19 infection. We investigated if patients with PCS also had evidence of a pro-thrombotic state associating with symptom severity.

In a large cohort of patients referred to a dedicated post-COVID-19 clinic, thrombotic risk including VWF(Ag):ADAMTS13 ratio, was investigated. An elevated VWF(Ag):ADAMTS13 ratio (≥1.5) was raised in nearly one-third of the cohort and four times more likely in patients with impaired exercise capacity as evidenced by desaturation ≥3% and/or rise in lactate level more than 1 from baseline on 1-minute sit to stand test and/or 6-minute walk test (p<0.0001). 20% (56/276) had impaired exercise capacity, of which 55% (31/56) had a raised VWF(Ag):ADAMTS13 ratio ≥1.5 (p<0.0001). FVIII and VWF(Ag) were elevated in 26% and 18% respectively and support a hypercoagulable state in some patients with PCS.

These findings suggest possible ongoing microvascular/endothelial dysfunction in the pathogenesis of PCS and highlight a potential role for antithrombotic therapy in the management of these patients.

Source: Prasannan N, Heightman M, Hillman T, Wall E, Bell R, Kessler A, Neave L, Doyle AJ, Devaraj A, Singh D, Dehbi HM, Scully M. Impaired exercise capacity in post-COVID syndrome: the role of VWF-ADAMTS13 axis. Blood Adv. 2022 May 11:bloodadvances.2021006944. doi: 10.1182/bloodadvances.2021006944. Epub ahead of print. PMID: 35543533; PMCID: PMC9098525. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9098525/ (Full text)

Autonomic dysfunction in long-COVID syndrome: a neurophysiological and neurosonology study

Dear Sirs,

A significant proportion of patients infected from SARS-CoV-2 experience new, recurring, or ongoing symptoms usually 3 months after infection that may last for weeks or months and comprise the so-called Long-COVID Syndrome (LCS). Most frequent neurological symptoms include fatigue, memory/attention deficits, sleep disorders, myalgias and hyposmia []. The occurrence of LCS is not associated with the severity of foregoing acute COVID-19 nor have specific predisposing factors been identified so far. LCS shares common features with two other diseases, Fibromyalgia (FM) and Chronic Fatigue Syndrome (CFS): young women are predominantly affected, the etiology is unknown, although a previous viral infection is suspected, and both conditions have symptoms similar to those of LCS. Autonomic Nervous System (ANS) maladaptation has been proposed as a possible pathogenetic underlying mechanism. [, ]

Hence, a case–control study was conducted to investigate if ANS dysfunction may contribute to LCS. Consecutive, adult patients, with history of laboratory-confirmed COVID-19 without hospitalization, presenting with persistent LCS symptoms for > 3 months from COVID-19 onset, including fatigue, cognitive impairment (brain fog), orthostatic dizziness, palpitations, breathlessness or gastrointestinal symptoms, were evaluated at a referral center in Athens, Greece (“Attikon” University Hospital) between September 2021 and December 2021. LCS patients with cardiovascular complications or diabetes were excluded. Controls included colleagues, nursing staff and volunteers without history of SARS-COV-2 infection, cardiovascular diseases, diabetes and ANS disorders. Evaluation of ANS function was performed by Sympathetic Skin Response (SSR) to investigate the Sympathetic Nervous System (SNS), and the cross-sectional area (CSA) of the Vagus Nerve (VN) was assessed by ultrasound to investigate the Parasympathetic Nervous System (PNS) []. A detailed description of the methods is available in the online-only supplement. The study was approved by the Institutional Research Bioethics. Informed consent was obtained by all participants. Statistical analysis was performed using the Statistical Package for Social Science (SPSS Inc., version 24.0 for Windows; IBM, Armonk, NY, USA). Descriptive statistics are given as the mean and standard deviation, frequency, and percentage. Statistical comparisons between different groups were performed using the chi-square test (or exact test) for binary outcomes, and Student’s t test or Mann–Whitney U test for continuous variables as appropriate.

Read the full article HERE.

Source: Papadopoulou M, Bakola E, Papapostolou A, Stefanou MI, Gaga M, Zouvelou V, Michopoulos I, Tsivgoulis G. Autonomic dysfunction in long-COVID syndrome: a neurophysiological and neurosonology study. J Neurol. 2022 May 10:1–2. doi: 10.1007/s00415-022-11172-1. Epub ahead of print. PMID: 35536408; PMCID: PMC9086662. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9086662/ (Full text)

Long COVID: A proposed hypothesis-driven model of viral persistence for the pathophysiology of the syndrome

Abstract:

Background: Long COVID (coronavirus disease 2019) syndrome includes a group of patients who, after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), exhibit lingering mild-to-moderate symptoms and develop medical complications that can have lasting health problems. In this report, we propose a model for the pathophysiology of the long COVID presentation based on increased proinflammatory cytokine production that results from the persistence of the SARS-CoV-2 virus or one of its molecular components. Associated with this hyperproduction of inflammatory cytokines is a heightened activity of nuclear factor κ B (NF-κB) and p38 mitogen-activated protein kinase signaling pathways that regulate cytokine production.

Objective: The purpose of the present report was to review the causes of long COVID syndrome and suggest ways that can provide a basis for a better understanding of the clinical symptomatology for the of improved diagnostic and therapeutic procedures for the condition.

Methods: Extensive research was conducted in medical literature data bases by applying terms such as “long COVID” associated with “persistence of the SARS-CoV-2 virus” “spike protein’ “COVID-19” and “biologic therapies.”

Results and Conclusions: In this model of the long COVID syndrome, the persistence of SARS-CoV-2 is hypothesized to trigger a dysregulated immune system with subsequent heightened release of proinflammatory cytokines that lead to chronic low-grade inflammation and multiorgan symptomatology. The condition seems to have a genetic basis, which predisposes individuals to have a diminished immunologic capacity to completely clear the virus, with residual parts of the virus persisting. This persistence of virus and resultant hyperproduction of proinflammatory cytokines are proposed to form the basis of the syndrome.

Source: Buonsenso D, Piazza M, Boner AL, Bellanti JA. Long COVID: A proposed hypothesis-driven model of viral persistence for the pathophysiology of the syndrome. Allergy Asthma Proc. 2022 May 1;43(3):187-193. doi: 10.2500/aap.2022.43.220018. PMID: 35524358. https://pubmed.ncbi.nlm.nih.gov/35524358/ https://www.ingentaconnect.com/content/ocean/aap/2022/00000043/00000003/art00003;jsessionid=pp9ea7gev7kv.x-ic-live-01#  (Full text available as download)

Prevalence of vitamin D deficiency among patients attending Post COVID-19 follow-up clinic: a cross-sectional study

Abstract:

Objective: Post-COVID-19 syndrome appears to be a multi-organ illness with a broad spectrum of manifestations, occurring after even mild acute illness. Limited data currently available has suggested that vitamin D deficiency may play a role in COVID-19 cases. However, to our knowledge, no study has examined the frequency of vitamin D deficiency in post-COVID-19 cases and its effect on the symptom severity. The aim of this study is to both screen the frequency of vitamin D deficiency in post-COVID-19 syndrome patients and to study its relation to persistent symptoms.

Patients and methods: A cross-sectional, single-center study was conducted involving all cases attending post-COVID-19 follow-up clinic from November 2020 to May 2021. Complete history, clinical examination, and laboratory analysis [kidney functions, serum calcium, C-reactive protein, serum ferritin, Serum 25-(OH) vitamin D] was done as well as HRCT chest.

Results: The study included 219 post-COVID-19 cases, 84% had deficient vitamin D levels (< 20 ng/dL); 11.4% had insufficient level (20-30 ng/dL) and only 4.9 % reported normal level. There was no link between levels of vitamin D with either the acute or post-COVID-19 symptoms in the studied groups.

Conclusions: Despite the prevalence of vitamin D deficiency among the study population, no association was observed between the levels of vitamin D and post-COVID-19 symptoms. It appears that post-COVID-19 syndrome pathophysiology involves a more complex interaction with the immune system. Dedicated clinical trials are advised to better study vitamin D levels and the related disease severity in COVID-19 patients.

Source: Mohamed Hussein AAR, Galal I, Amin MT, Moshnib AA, Makhlouf NA, Makhlouf HA, Abd-Elaal HK, Kholief KMS, Abdel Tawab DA, Kamal Eldin KA, Attia AM, Othman AEA, Shah J, Aiash H. Prevalence of vitamin D deficiency among patients attending Post COVID-19 follow-up clinic: a cross-sectional study. Eur Rev Med Pharmacol Sci. 2022 Apr;26(8):3038-3045. doi: 10.26355/eurrev_202204_28635. PMID: 35503606. https://www.europeanreview.org/article/28635 (Full text)

Long-Term Cardiovascular Effects of COVID-19: Emerging Data Relevant to the Cardiovascular Clinician

Abstract:

Purpose of review: COVID-19 is now a global pandemic and the illness affects multiple organ systems, including the cardiovascular system. Long-term cardiovascular consequences of COVID-19 are not yet fully characterized. This review seeks to consolidate available data on long-term cardiovascular complications of COVID-19 infection.

Recent findings: Acute cardiovascular complications of COVID-19 infection include myocarditis, pericarditis, acute coronary syndrome, heart failure, pulmonary hypertension, right ventricular dysfunction, and arrhythmia. Long-term follow-up shows increased incidence of arrhythmia, heart failure, acute coronary syndrome, right ventricular dysfunction, myocardial fibrosis, hypertension, and diabetes mellitus. There is increased mortality in COVID-19 patients after hospital discharge, and initial myocardial injury is associated with increased mortality. Emerging data demonstrates increased incidence of cardiovascular illness and structural changes in recovered COVID-19 patients. Future research will be important in understanding the clinical significance of these structural abnormalities, and to determine the effect of vaccines on preventing long-term cardiovascular complications.

Source: Tobler DL, Pruzansky AJ, Naderi S, Ambrosy AP, Slade JJ. Long-Term Cardiovascular Effects of COVID-19: Emerging Data Relevant to the Cardiovascular Clinician. Curr Atheroscler Rep. 2022 May 4:1–8. doi: 10.1007/s11883-022-01032-8. Epub ahead of print. PMID: 35507278; PMCID: PMC9065238. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9065238/ (Full text)

Clinical, radiological, and transbronchial biopsy findings in patients with long COVID-19: a case series

Abstract:

in English, Portuguese

This brief communication demonstrates the correlation of persistent respiratory symptoms with functional, tomographic, and transbronchial pulmonary biopsy findings in patients with COVID-19 who had a long follow-up period. We report a series of six COVID-19 patients with pulmonary involvement who presented with persistent dyspnea within 4-15 months of discharge. We performed transbronchial biopsies, and the histopathological pattern consistently demonstrated peribronchial remodeling with interstitial pulmonary fibrosis. Therefore, lung biopsy may be useful in the approach of patients with long COVID-19, although the type of procedure, its precise indication, and the moment to perform it are yet to be clarified.

(Brazilian Registry of Clinical Trials-ReBEC; identifier: RBR-8j9kqy [http://www.ensaiosclinicos.gov.br]).

Source: Baldi BG, Fabro AT, Franco AC, Machado MHC, Prudente RA, Franco ET, Marrone SR, Vale SAD, Cezare TJ, Moraes MPT, Ferreira EVM, Albuquerque ALP, Sawamura MVY, Tanni SE. Clinical, radiological, and transbronchial biopsy findings in patients with long COVID-19: a case series. J Bras Pneumol. 2022 Apr 29;48(3):e20210438. doi: 10.36416/1806-3756/e20210438. PMID: 35508067; PMCID: PMC9064656. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9064656/  (Full text)

Evidence mapping and review of long-COVID and its underlying pathophysiological mechanism

Abstract:

Purpose: Apart from the global disease burden of acute COVID-19 disease, the health complications arising after recovery have been recognized as a long-COVID or post-COVID-19 syndrome. Evidences of long-COVID symptoms involving various organ systems are rapidly growing in literature. The objective was to perform a rapid review and evidence mapping of systemic complications and symptoms of long-COVID and underlying pathophysiological mechanisms.

Methods: Publications reporting clinical trials, observational cohort studies, case-control studies, case-series, meta-analysis, and systematic reviews, focusing on the squeal of the disease, consequences of COVID-19 treatment/hospitalization, long-COVID, chronic COVID syndrome, and post acute COVID-19 were reviewed in detail for the narrative synthesis of frequency, duration, risk factors, and pathophysiology.

Results: The review highlights that pulmonary, neuro-psychological, and cardiovascular complications are major findings in most epidemiological studies. However, dysfunctional gastrointestinal, endocrine, and metabolic health are recent findings for which underlying pathophysiological mechanisms are poorly understood. Analysis of the clinical trial landscape suggests that more than 50% of the industry-sponsored trials are focused on pulmonary symptoms. In contrast to the epidemiological trends and academic trials, cardiovascular complications are not a focus of industry-sponsored trials, suggestive of the gaps in the research efforts.

Conclusion: The gap in epidemiological trends and academic trials, particularly concerning cardiovascular complications not being a focus of industry-sponsored trials is suggestive of the gaps in research efforts and longer follow-up durations would help identify other long-COVID-related health issues such as reproductive health and fertility.

Source: Umesh A, Pranay K, Pandey RC, Gupta MK. Evidence mapping and review of long-COVID and its underlying pathophysiological mechanism. Infection. 2022 Apr 30:1–14. doi: 10.1007/s15010-022-01835-6. Epub ahead of print. PMID: 35489015; PMCID: PMC9055372. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9055372/ (Full text)

Dissecting the Molecular Mechanisms Surrounding Post-COVID-19 Syndrome and Neurological Features

Abstract:

Many of the survivors of the novel coronavirus disease (COVID-19) are suffering from persistent symptoms, causing significant morbidity and decreasing their quality of life, termed “post-COVID-19 syndrome” or “long COVID”. Understanding the mechanisms surrounding PCS is vital to developing the diagnosis, biomarkers, and possible treatments.

Here, we describe the prevalence and manifestations of PCS, and similarities with previous SARS epidemics. Furthermore, we look at the molecular mechanisms behind the neurological features of PCS, where we highlight important neural mechanisms that may potentially be involved and pharmacologically targeted, such as glutamate reuptake in astrocytes, the role of NMDA receptors and transporters (EAAT2), ROS signaling, astrogliosis triggered by NF-κB signaling, KNDy neurons, and hypothalamic networks involving Kiss1 (a ligand for the G-protein-coupled receptor 54 (GPR54)), among others. We highlight the possible role of reactive gliosis following SARS-CoV-2 CNS injury, as well as the potential role of the hypothalamus network in PCS manifestations.

Source: Mohamed MS, Johansson A, Jonsson J, Schiöth HB. Dissecting the Molecular Mechanisms Surrounding Post-COVID-19 Syndrome and Neurological Features. Int J Mol Sci. 2022 Apr 12;23(8):4275. doi: 10.3390/ijms23084275. PMID: 35457093. https://www.mdpi.com/1422-0067/23/8/4275/htm (Full text)

Risk factors and multidimensional assessment of long COVID fatigue: a nested case-control study

Abstract:

Background: Fatigue is the most prevalent and debilitating long COVID symptom, however risk factors and pathophysiology of this condition remain unknown. We assessed risk factors for long COVID fatigue and explored its possible pathophysiology.

Methods: Nested case-control study in a COVID recovery clinic. Individuals with (cases) and without (controls) significant fatigue were included. We performed a multidimensional assessment evaluating various parameters, including pulmonary function tests and cardiopulmonary exercise testing, and implemented multivariable logistic regression to assess risk factors for significant long COVID fatigue.

Results: Total of 141 individuals were included. Mean age was 47 (SD 13) years; 115 (82%) were recovering from mild COVID-19. Mean time for evaluation was 8 months following COVID-19. Sixty-six (47%) individuals were classified with significant long COVID fatigue. They had significantly higher number of children, lower proportion of hypothyroidism, higher proportion of sore throat during acute illness and long COVID symptoms, and of physical limitation in daily activities. Individuals with fatigue had poorer sleep quality and higher degree of depression. They had significantly lower heart rate [153.52 (22.64) vs 163.52 (18.53), p=0.038] and oxygen consumption per Kg [27.69 (7.52) vs 30.71 (7.52), p=0.036] at peak exercise. The two independent risk factors for fatigue identified in multivariable analysis were peak exercise heart rate (odds ratio [OR] 0.79 per 10 beats/minute, 95% confidence interval [CI] 0.65-0.96, p=0.019); and long COVID memory impairment (OR 3.76, 95% CI 1.57-9.01, p=0.003).

Conclusions: Long COVID fatigue may be related to autonomic dysfunction, impaired cognition and decreased mood. This may suggest a limbic-vagal pathophysiology. Clinical Trial registration: NCT04851561.

Source: Margalit I, Yelin D, Sagi M, Rahat MM, Sheena L, Mizrahi N, Gordin Y, Agmon H, Epstein NK, Atamna A, Tishler O, Daitch V, Babich T, Abecasis D, Yarom Y, Kazum S, Shitenberg D, Baltaxe E, Elkana O, Shapira-Lichter I, Leibovici L, Yahav D. Risk factors and multidimensional assessment of long COVID fatigue: a nested case-control study. Clin Infect Dis. 2022 Apr 11:ciac283. doi: 10.1093/cid/ciac283. Epub ahead of print. PMID: 35403679.  https://pubmed.ncbi.nlm.nih.gov/35403679/