Tag: long covid pathomechanism

Proteomics of fibrin amyloid microclots in long COVID/post-acute sequelae of COVID-19 (PASC) shows many entrapped pro-inflammatory molecules that may also contribute to a failed fibrinolytic system

Abstract:

Background: Post-acute sequelae of COVID-19 (PASC), also now known as long COVID, has become a major global health and economic burden. Previously, we provided evidence that there is a significant insoluble fibrin amyloid microclot load in the circulation of individuals with long COVID, and that these microclots entrap a substantial number of inflammatory molecules, including those that might prevent clot breakdown. Scientifically, the most challenging aspect of this debilitating condition is that traditional pathology tests such as a serum CRP (C-reactive protein) may not show any significant abnormal inflammatory markers, albeit these tests measure only the soluble inflammatory molecules. Elevated, or abnormal soluble biomarkers such as IL-6, D-Dimer or fibrinogen indicate an increased risk for thrombosis or a host immune response in COVID-19. The absence of biomarkers in standard pathology tests, result in a significant amount of confusion for patients and clinicians, as patients are extremely sick or even bed-ridden but with no regular identifiable reason for their disease. Biomarkers that are currently available cannot detect the molecules present in the microclots we identified and are therefore unable to confirm their presence or the mechanisms that drive their formation.

Methods: Here we analysed the protein content of double-digested microclots of 99 long COVID patients and 29 healthy controls. The patients suffering from long COVID reported their symptoms through a questionnaire completed by themselves or their attending physician.

Results: Our long COVID cohort’s symptoms were found to be in line with global findings, where the most prevalent symptoms were constant fatigue (74%,) cognitive impairment (71%) and depression and anxiety (30%). Our most noteworthy findings were a reduced level of plasma Kallikrein compared to our controls, an increased level of platelet factor 4 (PF4) von Willebrand factor (VWF), and a marginally increased level of α-2 antiplasmin (α-2-AP). We also found a significant presence of antibodies entrapped inside these microclots.

Conclusion: Our results confirm the presence of pro-inflammatory molecules that may also contribute to a failed fibrinolysis phenomenon, which could possibly explain why individuals with long COVID suffer from chronic fatigue, dyspnoea, or cognitive impairment. In addition, significant platelet hyperactivation was noted. Hyperactivation will result in the granular content of platelets being shed into the circulation, including PF4. Overall, our results provide further evidence of both a failed fibrinolytic system in long COVID/PASC and the entrapment of many proteins whose presence might otherwise go unrecorded. These findings might have significant implications for individuals with pre-existing comorbidities, including cardiovascular disease and type 2 diabetes.

Source: Kruger A, Vlok M, Turner S, Venter C, Laubscher GJ, Kell DB, Pretorius E. Proteomics of fibrin amyloid microclots in long COVID/post-acute sequelae of COVID-19 (PASC) shows many entrapped pro-inflammatory molecules that may also contribute to a failed fibrinolytic system. Cardiovasc Diabetol. 2022 Sep 21;21(1):190. doi: 10.1186/s12933-022-01623-4. PMID: 36131342; PMCID: PMC9491257. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9491257/ (Full text)

Differential diagnosis and pathogenesis of the neurological signs and symptoms in COVID-19 and long-COVID syndrome

Abstract:

Neurological features have now been reported very frequently in the ongoing COVID-19 pandemic caused by SARS-CoV-2. The neurological deficits associated features are observed in both acute and chronic stages of COVID-19 and they appear to overlap with wide-ranging symptoms that can be attributed to being of non-neural origins, thus obscuring the definitive diagnosis of neuro-COVID.

The pathogenetic factors acting in concert to cause neuronal injury are now emerging, with SARS-CoV-2 directly affecting the brain coupled with the neuroinflammatory factors have been implicated in the causation of disabilities in acute COVID-19 and patients with Long-COVID syndrome. As the differentiation between a neural origin and other organ-based causation of a particular neurological feature is of prognostic significance, it implores a course of action to this covert, yet important neurological challenge.

Source: Baig AM. Differential diagnosis and pathogenesis of the neurological signs and symptoms in COVID-19 and long-COVID syndrome. CNS Neurosci Ther. 2022 Sep 19. doi: 10.1111/cns.13957. Epub ahead of print. PMID: 36117492. https://onlinelibrary.wiley.com/doi/10.1111/cns.13957 (Full text)

After the virus has cleared-Can preclinical models be employed for Long COVID research?

Abstract:

Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) can cause the life-threatening acute respiratory disease called COVID-19 (Coronavirus Disease 2019) as well as debilitating multiorgan dysfunction that persists after the initial viral phase has resolved. Long COVID or Post-Acute Sequelae of COVID-19 (PASC) is manifested by a variety of symptoms, including fatigue, dyspnea, arthralgia, myalgia, heart palpitations, and memory issues sometimes affecting between 30% and 75% of recovering COVID-19 patients. However, little is known about the mechanisms causing Long COVID and there are no widely accepted treatments or therapeutics.

After introducing the clinical aspects of acute COVID-19 and Long COVID in humans, we summarize the work in animals (mice, Syrian hamsters, ferrets, and nonhuman primates (NHPs)) to model human COVID-19. The virology, pathology, immune responses, and multiorgan involvement are explored. Additionally, any studies investigating time points longer than 14 days post infection (pi) are highlighted for insight into possible long-term disease characteristics.

Finally, we discuss how the models can be leveraged for treatment evaluation, including pharmacological agents that are currently in human clinical trials for treating Long COVID. The establishment of a recognized Long COVID preclinical model representing the human condition would allow the identification of mechanisms causing disease as well as serve as a vehicle for evaluating potential therapeutics.

Source: Jansen EB, Orvold SN, Swan CL, Yourkowski A, Thivierge BM, Francis ME, Ge A, Rioux M, Darbellay J, Howland JG, Kelvin AA. After the virus has cleared-Can preclinical models be employed for Long COVID research? PLoS Pathog. 2022 Sep 7;18(9):e1010741. doi: 10.1371/journal.ppat.1010741. PMID: 36070309; PMCID: PMC9451097. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9451097/ (Full text)

Severe fatigue as symptom of long COVID is characterized by increased expression of inflammatory genes in monocytes, increased serum pro-inflammatory cytokines, and increased CD8+ T-lymphocytes. A putative dysregulation of the immune-brain axis, the coagulation process, and auto-inflammation to explain the diversity of long COVID symptoms

Abstract:

Background. A significant proportion of patients with SARS-CoV-2 infection develops long COVID with fatigue as one of the most disabling symptoms. We performed clinical and immunologic profiling of fatigued and non-fatigued long COVID patients and age and gender matched healthy controls (HCs).

Methods. We included 37 long COVID patients with and 36 without severe fatigue and assessed inflammation-related monocyte gene expression, serum levels of inflammatory cytokines, and leukocyte and lymphocyte subsets 3-6 months after hospital discharge, and followed clinical symptoms up to one year.

Results. Long COVID with fatigue represented a severe variant with many symptoms (median 9 [IQR 5.0-10.0] symptoms) and signs of cognitive failure (41%) and depression (>24%). Symptoms persisted up to one year follow-up. Fatigued patients showed increased expression of inflammatory genes in monocytes, increased serum IL-6, TNF-α, galectin-9, and CXCL10, and increased CD8+ T-lymphocytes compared to HCs. Non-fatigued long COVID patients were arbitrarily divided in those with moderately severe disease (4 [2.5-5.0] symptoms, primarily impaired fitness, n=25) and those with mild disease (1 [1.0-2.0] symptom, n=11). Symptoms in non-fatigued long COVID patients persisted up to one year follow-up. Moderately severe patients showed reduced CD45RO- naive CD4+ T-lymphocytes and CD25+FOXP3+ regulatory CD4+ T-lymphocytes and limited monocyte and serum (galectin-9) inflammation. Mild patients showed monocyte and serum (IL-6, galectin-9) inflammation and decreased CD4+ T-lymphocyte subsets (T-helper 1 cells).

Conclusion. Long COVID with fatigue is associated with many concurrent and persistent symptoms up to one year after hospitalization and with clear signs of low grade inflammation and increased CD8+ T-lymphocytes. We showed that long COVID is a clinical and immunologic heterogeneous disorder. Diagnostic tools and personalized therapies combatting the diverse immune abnormalities might be required to alleviate the persisting disabling complaints of the patients.

Source: Julia C Berentschot, Hemmo A Drexhage, Daniel A Aynekulu Mersha, Annemarie JM Wijkhuijs, Corine H GeurtsvanKessel, Marion PG Koopmans, Jolanda Voermans, Majanka H Heijenbrok-Kal, L. Martine Bek, Gerard M Ribbers, Rita JG van den Berg-Emons, Joachim GJV Aerts, Willem A Dik, Merel E Hellemons. Severe fatigue as symptom of long COVID is characterized by increased expression of inflammatory genes in monocytes, increased serum pro-inflammatory cytokines, and increased CD8+ T-lymphocytes. A putative dysregulation of the immune-brain axis, the coagulation process, and auto-inflammation to explain the diversity of long COVID symptoms.  medRxiv 2022.09.15.22279970; doi: https://doi.org/10.1101/2022.09.15.22279970 (Full text available as PDF file)

Lots of long COVID treatment leads, but few are proven

As the current crisis phase of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic winds down—and the world nervously awaits potentially dangerous new variants—research into the nature and treatment of so-called long coronavirus disease (COVID) is beginning to ramp up. The White House has promised funding and a federal research roadmap, and dedicated clinics have started cropping up at academic medical centers across the country.

But attempts to understand and treat long COVID have been underway almost since the pandemic began. For more than 2 years, clinicians have been coping—mostly on their own—with streams of patients complaining of persistent symptoms or mysterious new ones after a bout with COVID-19 had seemingly resolved ( 1 ). And collectively, doctors and researchers have already made headway toward identifying some of the mechanisms underlying the condition—formally known as post-acute sequelae of COVID (PASC).

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Source: Leah Shaffer. Lots of long COVID treatment leads, but few are proven. Vol. 119 | No. 36. https://www.pnas.org/doi/10.1073/pnas.2213524119 (Full text)

Lowered Quality of Life in Long COVID Is Predicted by Affective Symptoms, Chronic Fatigue Syndrome, Inflammation and Neuroimmunotoxic Pathways

Abstract:

The physio-affective phenome of Long COVID-19 is predicted by (a) immune-inflammatory biomarkers of the acute infectious phase, including peak body temperature (PBT) and oxygen saturation (SpO2), and (b) the subsequent activation of immune and oxidative stress pathways during Long COVID. The purpose of this study was to delineate the effects of PBT and SpO2 during acute infection, as well as the increased neurotoxicity on the physical, psychological, social and environmental domains of health-related quality of life (HR-QoL) in people with Long COVID.

We recruited 86 participants with Long COVID and 39 normal controls, assessed the WHO-QoL-BREF (World Health Organization Quality of Life Instrument-Abridged Version, Geneva, Switzerland) and the physio-affective phenome of Long COVID (comprising depression, anxiety and fibromyalgia-fatigue rating scales) and measured PBT and SpO2 during acute infection, and neurotoxicity (NT, comprising serum interleukin (IL)-1β, IL-18 and caspase-1, advanced oxidation protein products and myeloperoxidase, calcium and insulin resistance) in Long COVID.

We found that 70.3% of the variance in HR-QoL was explained by the regression on the physio-affective phenome, lowered calcium and increased NT, whilst 61.5% of the variance in the physio-affective phenome was explained by calcium, NT, increased PBT, lowered SpO2, female sex and vaccination with AstraZeneca and Pfizer. The effects of PBT and SpO2 on lowered HR-QoL were mediated by increased NT and lowered calcium yielding increased severity of the physio-affective phenome which largely affects HR-QoL.

In conclusion, lowered HR-Qol in Long COVID is largely predicted by the severity of neuro-immune and neuro-oxidative pathways during acute and Long COVID.

Source: Maes M, Al-Rubaye HT, Almulla AF, Al-Hadrawi DS, Stoyanova K, Kubera M, Al-Hakeim HK. Lowered Quality of Life in Long COVID Is Predicted by Affective Symptoms, Chronic Fatigue Syndrome, Inflammation and Neuroimmunotoxic Pathways. Int J Environ Res Public Health. 2022 Aug 19;19(16):10362. doi: 10.3390/ijerph191610362. PMID: 36011997. https://www.mdpi.com/1660-4601/19/16/10362/htm (Full text)

Prevalence of symptoms, comorbidities, fibrin amyloid microclots and platelet pathology in individuals with Long COVID/Post-Acute Sequelae of COVID-19 (PASC)

Abstract:

Background: Fibrin(ogen) amyloid microclots and platelet hyperactivation previously reported as a novel finding in South African patients with the coronavirus 2019 disease (COVID-19) and Long COVID/Post-Acute Sequelae of COVID-19 (PASC), might form a suitable set of foci for the clinical treatment of the symptoms of Long COVID/PASC. A Long COVID/PASC Registry was subsequently established as an online platform where patients can report Long COVID/PASC symptoms and previous comorbidities.

Methods: In this study, we report on the comorbidities and persistent symptoms, using data obtained from 845 South African Long COVID/PASC patients. By using a previously published scoring system for fibrin amyloid microclots and platelet pathology, we also analysed blood samples from 80 patients, and report the presence of significant fibrin amyloid microclots and platelet pathology in all cases.

Results: Hypertension, high cholesterol levels (dyslipidaemia), cardiovascular disease and type 2 diabetes mellitus (T2DM) were found to be the most important comorbidities. The gender balance (70% female) and the most commonly reported Long COVID/PASC symptoms (fatigue, brain fog, loss of concentration and forgetfulness, shortness of breath, as well as joint and muscle pains) were comparable to those reported elsewhere. These findings confirmed that our sample was not atypical. Microclot and platelet pathologies were associated with Long COVID/PASC symptoms that persisted after the recovery from acute COVID-19.

Conclusions: Fibrin amyloid microclots that block capillaries and inhibit the transport of O2 to tissues, accompanied by platelet hyperactivation, provide a ready explanation for the symptoms of Long COVID/PASC. Removal and reversal of these underlying endotheliopathies provide an important treatment option that urgently warrants controlled clinical studies to determine efficacy in patients with a diversity of comorbidities impacting on SARS-CoV-2 infection and COVID-19 severity. We suggest that our platelet and clotting grading system provides a simple and cost-effective diagnostic method for early detection of Long COVID/PASC as a major determinant of effective treatment, including those focusing on reducing clot burden and platelet hyperactivation.

Source: Pretorius E, Venter C, Laubscher GJ, Kotze MJ, Oladejo SO, Watson LR, Rajaratnam K, Watson BW, Kell DB. Prevalence of symptoms, comorbidities, fibrin amyloid microclots and platelet pathology in individuals with Long COVID/Post-Acute Sequelae of COVID-19 (PASC). Cardiovasc Diabetol. 2022 Aug 6;21(1):148. doi: 10.1186/s12933-022-01579-5. PMID: 35933347; PMCID: PMC9356426. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9356426/ (Full text)

Long COVID endotheliopathy: hypothesized mechanisms and potential therapeutic approaches

Abstract:

SARS-CoV-2–infected individuals may suffer a multi–organ system disorder known as “long COVID” or post-acute sequelae of SARS-CoV-2 infection (PASC). There are no standard treatments, the pathophysiology is unknown, and incidence varies by clinical phenotype.

Acute COVID-19 correlates with biomarkers of systemic inflammation, hypercoagulability, and comorbidities that are less prominent in PASC. Macrovessel thrombosis, a hallmark of acute COVID-19, is less frequent in PASC. Female sex at birth is associated with reduced risk for acute COVID-19 progression, but with increased risk of PASC. Persistent microvascular endotheliopathy associated with cryptic SARS-CoV-2 tissue reservoirs has been implicated in PASC pathology.

Autoantibodies, localized inflammation, and reactivation of latent pathogens may also be involved, potentially leading to microvascular thrombosis, as documented in multiple PASC tissues. Diagnostic assays illuminating possible therapeutic targets are discussed.

Source: Ahamed J, Laurence J. Long COVID endotheliopathy: hypothesized mechanisms and potential therapeutic approaches. J Clin Invest. 2022 Aug 1;132(15):e161167. doi: 10.1172/JCI161167. PMID: 35912863; PMCID: PMC9337829. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9337829/ (Full text)

Transient receptor potential melastatin 3 dysfunction in post COVID-19 condition and myalgic encephalomyelitis/chronic fatigue syndrome patients

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a severe multisystemic condition associated with post-infectious onset, impaired natural killer (NK) cell cytotoxicity and impaired ion channel function, namely Transient Receptor Potential Melastatin 3 (TRPM3). Long-term effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has resulted in neurocognitive, immunological, gastrointestinal, and cardiovascular manifestations recently recognised as post coronavirus disease 2019 (COVID-19) condition. The symptomatology of ME/CFS overlaps significantly with post COVID-19; therefore, this research aimed to investigate TRPM3 ion channel function in post COVID-19 condition patients.

Methods: Whole-cell patch-clamp technique was used to measure TRPM3 ion channel activity in isolated NK cells of N = 5 ME/CFS patients, N = 5 post COVID-19 patients, and N = 5 healthy controls (HC). The TRPM3 agonist, pregnenolone sulfate (PregS) was used to activate TRPM3 function, while ononetin was used as a TRPM3 antagonist.

Results: As reported in previous research, PregS-induced TRPM3 currents were significantly reduced in ME/CFS patients compared with HC (p = 0.0048). PregS-induced TRPM3 amplitude was significantly reduced in post COVID-19 condition compared with HC (p = 0.0039). Importantly, no significant difference was reported in ME/CFS patients compared with post COVID-19 condition as PregS-induced TRPM3 currents of post COVID-19 condition patients were similar of ME/CFS patients currents (p > 0.9999). Isolated NK cells from post COVID-19 condition and ME/CFS patients were resistant to ononetin and differed significantly with HC (p < 0.0001).

Conclusion: The results of this investigation suggest that post COVID-19 condition patients may have impaired TRPM3 ion channel function and provide further evidence regarding the similarities between post COVID-19 condition and ME/CFS. Impaired TRPM3 channel activity in post COVID-19 condition patients suggest impaired ion mobilisation which may consequently impede cell function resulting in chronic post-infectious symptoms. Further investigation into TRPM3 function may elucidate the pathomechanism, provide a diagnostic and therapeutic target for post COVID-19 condition patients and commonalities with ME/CFS patients.

Source: Sasso EM, Muraki K, Eaton-Fitch N, Smith P, Lesslar OL, Deed G, Marshall-Gradisnik S. Transient receptor potential melastatin 3 dysfunction in post COVID-19 condition and myalgic encephalomyelitis/chronic fatigue syndrome patients. Mol Med. 2022 Aug 19;28(1):98. doi: 10.1186/s10020-022-00528-y. PMID: 35986236.  https://molmed.biomedcentral.com/articles/10.1186/s10020-022-00528-y (Full text)

Rationale for Nicotinamide Adenine Dinucleotide (NAD+) Metabolome Disruption as a Pathogenic Mechanism of Post-Acute COVID-19 Syndrome

Abstract:

Many acute COVID-19 convalescents experience a persistent sequelae of infection, called post-acute COVID-19 syndrome (PACS). With incidence ranging between 31% and 69%, PACS is becoming increasingly acknowledged as a new disease state in the context of SARS-CoV-2 infection. As SARS-CoV-2 infection can affect several organ systems to varying degrees and durations, the cellular and molecular abnormalities contributing to PACS pathogenesis remain unclear.

Despite our limited understanding of how SARS-CoV-2 infection promotes this persistent disease state, mitochondrial dysfunction has been increasingly recognized as a contributing factor to acute SARS-CoV-2 infection and, more recently, to PACS pathogenesis. The biological mechanisms contributing to this phenomena have not been well established in previous literature; however, in this review, we summarize the evidence that NAD+ metabolome disruption and subsequent mitochondrial dysfunction following SARS-CoV-2 genome integration may contribute to PACS biological pathogenesis.

We also briefly examine the coordinated and complex relationship between increased oxidative stress, inflammation, and mitochondrial dysfunction and speculate as to how SARS-CoV-2-mediated NAD+ depletion may be causing these abnormalities in PACS. As such, we present evidence supporting the therapeutic potential of intravenous administration of NAD+ as a novel treatment intervention for PACS symptom management.

Source: Block T, Kuo J. Rationale for Nicotinamide Adenine Dinucleotide (NAD+) Metabolome Disruption as a Pathogenic Mechanism of Post-Acute COVID-19 Syndrome. Clin Pathol. 2022 Jun 24;15:2632010X221106986. doi: 10.1177/2632010X221106986. PMID: 35769168; PMCID: PMC9234841. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9234841/ (Full text)