Tag: complement system

COVID-19 Antibody Discovery Could Explain Long COVID

Press Release:

UVA Health researchers have discovered a potential explanation for some of the most perplexing mysteries of COVID-19 and long COVID. The surprising findings could lead to new treatments for the difficult acute effects of COVID-19, long COVID and possibly other viruses.

Researchers led by UVA’s Steven L. Zeichner, MD, PhD, found that COVID-19 may prompt some people’s bodies to make antibodies that act like enzymes that the body naturally uses to regulate important functions – blood pressure, for example. Related enzymes also regulate other important body functions, such as blood clotting and inflammation.

Doctors may be able to target these “abzymes” to stop their unwanted effects. If abzymes with rogue activities are also responsible for some of the features of long COVID, doctors could target the abzymes to treat the difficult and sometimes mysterious symptoms of COVID-19 and long COVID at the source, instead of merely treating the downstream symptoms.

“Some patients with COVID-19 have serious symptoms and we have trouble understanding their cause. We also have a poor understanding of the causes of long COVID,” said Zeichner, a pediatric infectious disease expert at UVA Children’s. “Antibodies that act like enzymes are called ‘abzymes.’ Abzymes are not exact copies of enzymes and so they work differently, sometimes in ways that the original enzyme does not. If COVID-19 patients are making abzymes, it is possible that these rogue abzymes could harm many different aspects of physiology. If this turns out to be true, then developing treatments to deplete or block the rogue abzymes could be the most effective way to treat the complications of COVID-19.”

Understanding COVID-19 Abzymes

SARS-CoV-2, the virus that causes COVID, has protein on its surface called the Spike protein. When the virus begins to infect a cell, the Spike protein binds a protein called Angiotensin Converting Enzyme 2, or ACE2, on the cell’s surface. ACE2’s normal function in the body is to help regulate blood pressure; it cuts a protein called angiotensin II to make a derivative protein called angiotensin 1-7. Angiotensin II constricts blood vessels, raising blood pressure, while angiotensin 1-7 relaxes blood vessels, lowering blood pressure.

Zeichner and his team thought that some patients might make antibodies against the Spike protein that looked enough like ACE2 so that the antibodies also had enzymatic activity like ACE2, and that is exactly what they found.

Recently, other groups have found that some patients with long COVID have problems with their coagulation systems and with another system called “complement.” Both the coagulation system and the complement system are controlled by enzymes in the body that cut other proteins to activate them. If patients with long COVID make abzymes that activate proteins that control processes such as coagulation and inflammation, that could explain the source of some of the long COVID symptoms and why long COVID symptoms persist even after the body has cleared the initial infection. It also may explain rare side effects of COVID-19 vaccination.

To determine if antibodies could be having unexpected effects in COVID patients, Zeichner and his collaborators examined plasma samples collected from 67 volunteers with moderate or severe COVID on or around day 7 of their hospitalization. The researchers compared what they found with plasma collected in 2018, prior to the beginning of the pandemic. The results showed that a small subset of the COVID patients had antibodies that acted like enzymes.

While our understanding of the potential role of abzymes in COVID-19 is still in its early stages, enzymatic antibodies have already been detected in certain cases of HIV, Zeichner notes. That means there is precedent for a virus to trigger abzyme formation. It also suggests that other viruses may cause similar effects.

Zeichner, who is developing a universal coronavirus vaccine, expects UVA’s new findings will renew interest in abzymes in medical research. He also hopes his discovery will lead to better treatments for patients with both acute COVID-19 and long COVID.

“We now need to study pure versions of antibodies with enzymatic activity to see how abzymes may work in more detail, and we need to study patients who have had COVID-19 who did and did not develop long COVID,” he said. “There is much more work to do, but I think we have made a good start in developing a new understanding of this challenging disease that has caused so much distress and death around the world. The first step to developing effective new therapies for a disease is developing a good understanding of the disease’s underlying causes, and we have taken that first step.”

Findings Published

The researchers have published their findings in the scientific journal mBio, a publication of the American Society for Microbiology. The research team consisted of Yufeng Song, Regan Myers, Frances Mehl, Lila Murphy, Bailey Brooks, and faculty members from the Department of Medicine, Jeffrey M. Wilson, Alexandra Kadl, Judith Woodfolk.

“It’s great to have such talented and dedicated colleagues here at UVA who are excited about working on new and unconventional research projects,” said Zeichner.

Zeichner is the McClemore Birdsong Professor in the University of Virginia School of Medicine’s Departments of Pediatrics and Microbiology, Immunology and Cancer Biology; the director of the Pendleton Pediatric Infectious Disease Laboratory; and part of UVA Children’s Child Health Research Center.

The abzyme research was supported by UVA, including the Manning Fund for COVID-19 Research at UVA; the Ivy Foundation; the Pendleton Laboratory Fund for Pediatric Infectious Disease Research; a College Council Minerva Research Grant; the Coulter Foundation; and the National Institutes of Health’s National Institute of Allergy and Infection Diseases, grant R01 AI176515. Additional support came from the HHV-6 Foundation.

Source: UVA Health News

Role of the complement system in Long COVID

Abstract:

Long COVID, or Post-Acute COVID Syndrome (PACS), may develop following SARS-CoV-2 infection, posing a substantial burden to society. Recently, PACS has been linked to a persistent activation of the complement system (CS), offering hope for both a diagnostic tool and targeted therapy. However, our findings indicate that, after adjusting proteomics data for age, body mass index and sex imbalances, the evidence of complement system activation disappears.

Furthermore, proteomic analysis of two orthogonal cohorts—one addressing PACS following severe acute phase and another after a mild acute phase—fails to support the notion of persistent CS activation. Instead, we identify a proteomic signature indicative of either ongoing infections or sustained immune activation similar to that observed in acute COVID-19, particularly within the mild-PACS cohort.

Source: Vadim Farztdinov, Boris Zühlke, Franziska Sotzny, Fridolin Steinbeis, Martina Seifert, Claudia Kedor, Kirsten Wittke, Pinkus Tober-Lau, Thomas Zoller, Kathrin Textoris-Taube, Daniela Ludwig, Clemens Dierks, Dominik Bierbaum, Leif Erik Sander, Leif G Hanitsch, Martin Witzenrath, Florian Kurth, Michael Mülleder, Carmen Scheibenbogen, Markus Ralser. Role of the complement system in Long COVID. medRxiv 2024.03.14.24304224; doi: https://doi.org/10.1101/2024.03.14.24304224 https://www.medrxiv.org/content/10.1101/2024.03.14.24304224v1.full-text (Full text)

Unraveling Links between Chronic Inflammation and Long COVID: Workshop Report

As COVID-19 continues, an increasing number of patients develop long COVID symptoms varying in severity that last for weeks, months, or longer. Symptoms commonly include lingering loss of smell and taste, hearing loss, extreme fatigue, and “brain fog.” Still, persistent cardiovascular and respiratory problems, muscle weakness, and neurologic issues have also been documented. A major problem is the lack of clear guidelines for diagnosing long COVID. Although some studies suggest that long COVID is due to prolonged inflammation after SARS-CoV-2 infection, the underlying mechanisms remain unclear.

The broad range of COVID-19’s bodily effects and responses after initial viral infection are also poorly understood. This workshop brought together multidisciplinary experts to showcase and discuss the latest research on long COVID and chronic inflammation that might be associated with the persistent sequelae following COVID-19 infection.

Source: Pushpa Tandon, Natalie D. Abrams, Leela Rani Avula, Danielle M. Carrick, Preethi Chander, Rao L. Divi, Johanna T. Dwyer, Gallya Gannot, Nataliya Gordiyenko, Qian Liu, Kyung Moon, Mercy PrabhuDas, Anju Singh, Mulualem E. Tilahun, Merriline M. Satyamitra, Chiayeng Wang, Ronald Warren, Christina H. Liu; Unraveling Links between Chronic Inflammation and Long COVID: Workshop Report. J Immunol 15 February 2024; 212 (4): 505–512. https://doi.org/10.4049/jimmunol.2300804 https://journals.aai.org/jimmunol/article/212/4/505/266648 (Full text)

Persistent complement dysregulation with signs of thromboinflammation in active Long Covid

Abstract:

Long Covid is a debilitating condition of unknown etiology. We performed multimodal proteomics analyses of blood serum from COVID-19 patients followed up to 12 months after confirmed severe acute respiratory syndrome coronavirus 2 infection. Analysis of >6500 proteins in 268 longitudinal samples revealed dysregulated activation of the complement system, an innate immune protection and homeostasis mechanism, in individuals experiencing Long Covid.

Thus, active Long Covid was characterized by terminal complement system dysregulation and ongoing activation of the alternative and classical complement pathways, the latter associated with increased antibody titers against several herpesviruses possibly stimulating this pathway. Moreover, markers of hemolysis, tissue injury, platelet activation, and monocyte–platelet aggregates were increased in Long Covid. Machine learning confirmed complement and thromboinflammatory proteins as top biomarkers, warranting diagnostic and therapeutic interrogation of these systems.

Source: Carlo Cervia-Hasler et al. Persistent complement dysregulation with signs of thromboinflammation in active Long Covid. Science383,eadg7942(2024). DOI: 10.1126/science.adg7942 https://www.science.org/doi/10.1126/science.adg7942 (Full text)

Complement dysregulation is a predictive and therapeutically amenable feature of long COVID

Abstract:

Background Long COVID encompasses a heterogeneous set of ongoing symptoms that affect many individuals after recovery from infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The underlying biological mechanisms nonetheless remain obscure, precluding accurate diagnosis and effective intervention. Complement dysregulation is a hallmark of acute COVID-19 but has not been investigated as a potential determinant of long COVID.

Methods We quantified a series of complement proteins, including markers of activation and regulation, in plasma samples from healthy convalescent individuals with a confirmed history of infection with SARS-CoV-2 and age/ethnicity/gender/infection/vaccine-matched patients with long COVID.

Findings Markers of classical (C1s-C1INH complex), alternative (Ba, iC3b), and terminal pathway (C5a, TCC) activation were significantly elevated in patients with long COVID. These markers in combination had a receiver operating characteristic predictive power of 0.794. Other complement proteins and regulators were also quantitatively different between healthy convalescent individuals and patients with long COVID. Generalized linear modeling further revealed that a clinically tractable combination of just four of these markers, namely the activation fragments iC3b, TCC, Ba, and C5a, had a predictive power of 0.785.

Conclusions These findings suggest that complement biomarkers could facilitate the diagnosis of long COVID and further suggest that currently available inhibitors of complement activation could be used to treat long COVID.

Source: Kirsten Baillie, Helen E Davies, Samuel B K Keat, Kristin Ladell, Kelly L Miners, Samantha A Jones, Ermioni Mellou, Erik J M Toonen, David A Price, B Paul Morgan, Wioleta M Zelek. Complement dysregulation is a predictive and therapeutically amenable feature of long COVID.
medRxiv 2023.10.26.23297597; doi: https://doi.org/10.1101/2023.10.26.23297597 https://www.medrxiv.org/content/10.1101/2023.10.26.23297597v1.full-text (Full text)

Immunological Patient Stratification in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex disease characterized by profound fatigue, post-exertional malaise (PEM), and neurocognitive dysfunction. Immune dysregulation and gastrointestinal symptoms are commonly observed in ME/CFS patients. Despite affecting approximately 0.89% of the general population, the underlying pathophysiological mechanisms remain poorly understood. This study aimed to elucidate the relationship between immunological characteristics and intestinal barrier function in ME/CFS patients.

ME/CFS patients were stratified into two groups based on their immune competence. After documentation of detailed medical records, serum and plasma samples were collected for assessment of inflammatory immune mediators and biomarkers for intestinal barrier integrity by ELISA. We found reduced complement protein C4a levels in immunodeficient ME/CFS patients suggesting a sub-group specific innate immune dysregulation. ME/CFS patients without immunodeficiencies exhibit a mucosal barrier leakage, as indicated by elevated levels of Lipopolysaccharide-binding protein (LBP).

Stratifying ME/CFS patients based on immune competence enabled the distinction of two subgroups with different pathophysiological patterns. The study highlights the importance of emphasizing precise patient stratification in ME/CFS, particularly in the context of defining suitable treatment strategies. Given the substantial health and socioeconomic burden associated with ME/CFS, urgent attention and research efforts are needed to define causative treatment approaches.

Source: Rohrhofer, J.; Hauser, L.; Lettenmaier, L.; Lutz, L.; Koidl, L.; Gentile, S.A.; Ret, D.; Stingl, M.; Untersmayr, E. Immunological Patient Stratification in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Preprints 2023, 2023112007. https://doi.org/10.20944/preprints202311.2007.v1 https://www.preprints.org/manuscript/202311.2007/v1 (Full text available as PDF file)

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)

Relevance of complement immunity with brain fog in patients with long COVID

Abstract:

Introduction: This study aimed to elucidate the prevalence and clinical characteristics of patients with long COVID (coronavirus disease 2019), especially focusing on 50% hemolytic complement activity (CH50).

Methods: This retrospective observational study focused on patients who visited Okayama University Hospital (Japan) for the treatment of long COVID between February 2021 and March 2023. CH50 levels were measured using liposome immunometric assay (Autokit CH50 Assay, FUJIFILM Wako Pure Chemical Corporation, Japan); high CH50 was defined as ≥59 U/mL. Univariate analyses assessed differences in the clinical background, long COVID symptoms, inflammatory markers, and clinical scores of patients with normal and high CH50. Logistic regression model investigated the association between high CH50 levels and these factors.

Results: Of 659 patients who visited our hospital, 478 patients were included. Of these, 284 (59.4%) patients had high CH50 levels. Poor concentration was significantly more frequent in the high CH50 group (7.2% vs. 13.7%), whereas no differences were observed in other subjective symptoms (fatigue, headache, insomnia, dyspnea, tiredness, and brain fog). Multivariate analysis was performed on factors that could be associated with poor concentration, suggesting a significant relationship to high CH50 levels (adjusted odds ratio [aOR], 2.70; 95% confidence interval [CI], 1.33–5.49). Also, high CH50 was significantly associated with brain fog (aOR, 1.66; 95% CI, 1.04–2.66).

Conclusions: High CH50 levels were frequently reported in individuals with long COVID, indicating a relationship with brain fog. Future in-depth research should examine the pathological role and causal link between complement immunity and the development of long COVID.

Source: Hagiya H, Tokumasu K, Otsuka Y, Sunada N, Nakano Y, Honda H, Furukawa M, Otsuka F. Relevance of complement immunity with brain fog in patients with long COVID. J Infect Chemother. 2023 Oct 20:S1341-321X(23)00261-1. doi: 10.1016/j.jiac.2023.10.016. Epub ahead of print. PMID: 37866620. https://www.sciencedirect.com/science/article/abs/pii/S1341321X23002611

Long COVID: Clinical Findings, Pathology, and Endothelial Molecular Mechanisms

Abstract:

Persistence of COVID-19 symptoms may follow SARS-CoV-2 infection. The incidence of long COVID increases with the severity of acute disease, but even mild disease can be associated with sequelae. The symptoms vary widely with fatigue, shortness of breath, and cognitive dysfunction being the most common. Abnormalities of multiple organs have been documented and histopathology has revealed widespread microthrombi. Elevated levels of complement are present in acute COVID-19 patients and may persist at lower levels in long COVID. Evidence supports complement activation with endotheliopathy associated disease as the molecular mechanism causing both acute and long COVID.

Section snippets

Prevalence and Definition: A review and meta-analysis of published results of long COVID studies suggest a global prevalence of the post COVID-19 condition of approximately 43% with a wide range of 9-81%.1 Using a population-representative survey epidemiologists have estimated the prevalence of long COVID in the United States to be 7.3%.2 In an effort to standardize the definition of long COVID the World Health Organization (WHO) established a Clinical Case Definition Working Group on the Post-COVID-19 Condition.3

Symptoms: The symptoms of long COVID are similar to those observed in patients following chronic critical illness and hospitalization in intensive care units.4 In the United Kingdom a retrospective matched cohort study was undertaken to determine symptoms beyond 12 weeks in non-hospitalized SARS-CoV-2 infected patients compared with uninfected patients.5 A cohort of 486,149 non-hospitalized adults with confirmed SARS-CoV-2 infection was compared to 1,944,580 propensity score-matched adults with no record

Evaluation and Testing: The previously referenced study of COVID patients 6 months after discharge from hospital in Wuhan, China enrolled patients in radiographic, pulmonary function, and blood testing.7 High resolution computerized tomography (HRCT) was performed on 390 patients and was abnormal in 52% not requiring supplemental oxygen and 54% of patients requiring supplemental oxygen. Lung diffusion impairment was noted in 22% of patients not requiring oxygen and up to 56% of patients requiring supplemental oxygen

Pathology and Histopathology: Autopsy data has contributed considerable information to our understanding of SARS-CoV-2 infection. A review of the histopathological findings in coronavirus disease 2019 reported diffuse alveolar damage (DAD), multiple organ microvasculitis, and lymphocytic infiltration with changes in immune organs and emphasized the observance of microthrombosis in numerous studies.18 An autopsy study from New York Presbyterian Hospital revealed macroscopic and/or microscopic thrombi in 84% patients.19

Complement, von Willebrand factor, and Endotheliopathy: A prospective study in the Netherlands was conducted to examine the role of complement as a component of the innate immune response to SARS-CoV-2 infection.29 Investigators found that complement factors C3a, C3c, and the terminal complement complex or membrane attack complex (MAC) were increased in COVID-19 patients compared to healthy controls. Furthermore, these complement factors were more increased in patients who were admitted to intensive care units, died, or experienced thromboembolic

Discussion: Long COVID or post acute sequelae of COVID-19 (PASC) is a frequent occurrence in patients recovering from acute SARS-CoV-2 infection. Estimates of the incidence vary widely with the more recent estimates trending below 10% in the United States. Changes in definition, increasing population immunity, treatment with antivirals and monoclonal antibodies, and newer variants may all play a role in the downward trend. The symptoms of long COVID are numerous and reflect the multi-organ nature of both…

Conclusion: The pathology and histopathology of COVID-19 patients has demonstrated the presence of widespread multi-organ microthrombi as a central feature of SARS-CoV-2 infection. Elevated levels of complement factors and von Willebrand factor have been found in COVID-19 patients and the degree of increases are directly related to the severity of disease and persistent high levels correlate with long COVID symptoms.39 Persisting symptoms following acute COVID-19 occur more often and are more debilitating

Source: Hawley HB. Long COVID: Clinical Findings, Pathology, and Endothelial Molecular Mechanisms. Am J Med. 2023 Sep 11:S0002-9343(23)00539-9. doi: 10.1016/j.amjmed.2023.08.008. Epub ahead of print. PMID: 37704072. https://www.sciencedirect.com/science/article/abs/pii/S0002934323005399

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)