Long COVID (PASC) Is Maintained by a Self-Sustaining Pro-Inflammatory TLR4/RAGE-Loop of S100A8/A9 > TLR4/RAGE Signalling, Inducing Chronic Expression of IL-1b, IL-6 and TNFa: Anti-Inflammatory Ezrin Peptides as Potential Therapy

Abstract:

Long COVID, also referred to as Post-Acute Sequelae of COVID (PASC), is probably triggered during SARS-CoV-2 infection and acute COVID-19 by SARS-CoV-2 Spike-protein binding and hyper-activating the cell-membrane expressed Receptor for Advance Glycation End-products (mRAGE) and Toll-Like Receptor 4 (TLR4). SARS-CoV-2 infects lung monocytes by Spike binding to mRAGE (not ACE2).
During acute COVID-19, high levels of IL-6 hyper-stimulate S100A8/A9 expression and secretion. Although no viral protein nor mRNA can be detected in half of long COVID (PASC) patients, there is a significant elevation of serum levels of IL-1b, IL-6, TNFa, and S100A8/A9. It appears that a pathological pro-inflammatory feedback loop (the TLR4/RAGE-loop) is established during acute COVID-19, which is maintained by S100A8/A9 > RAGE/TLR4 chronic inflammatory signalling, even after SARS-CoV-2 has been cleared from the body. During long COVID/PASC, Ca2+-binding protein S100A8/A9 chronically stimulates TLR4/RAGE-signalling to induce chronic expression of IL-1b, IL-6 and TNFa. Secreted IL-6 binds to its IL-6R receptor on the surface of other cells and signals via STAT3 and C/EBPb for more S100A8/A9 expression. Secreted IL-1b binds to its receptor IL-1R on other cells, and signals via NFkB for more mRAGE and TLR4 expression. New S100A8/A9 can bind and activate cell-surface mRAGE and TLR4 to stimulate expression of more IL-1b, IL-6 and TNFa.
This process establishes a pathogenic pro-inflammatory TLR4/RAGE-loop: IL-1b + IL-6 > IL-1R + IL-6R > TLR4/mRAGE + S100A8/A9 > IL-1b + IL-6, which generates multi-organ inflammation that persists in the blood vessels, the brain, the liver, the heart, the kidneys, the gut and the musculo-skeletal system, and is responsible for all the complex pathologies associated with long COVID/PASC. Chronic expression of IL-1, IL-6 and TNFa is critical for the maintenance of the TLR4/RAGE-loop and persistence of long COVID/PASC.
Ezrin peptides are inhibitors of IL-1, IL-6, IL-8 and TNFa expression, so are now being investigated as potential therapy for long COVID/PASC. There is preliminary anecdotal evidence of symptomatic relief (not confirmed yet by formal clinical trials) from a few long COVID/PASC patient volunteers, after treatment with ezrin peptide therapy.
Source: Holms RD. Long COVID (PASC) Is Maintained by a Self-Sustaining Pro-Inflammatory TLR4/RAGE-Loop of S100A8/A9 > TLR4/RAGE Signalling, Inducing Chronic Expression of IL-1b, IL-6 and TNFa: Anti-Inflammatory Ezrin Peptides as Potential Therapy. Immuno. 2022; 2(3):512-533. https://doi.org/10.3390/immuno2030033 https://www.mdpi.com/2673-5601/2/3/33 (Full text)

Studies find that microbiome changes may be a signature for ME/CFS

Researchers have found differences in the gut microbiomes of people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) compared to healthy controls. Findings from two studies, published in Cell Host & Microbe and funded by the National Institutes of Health add to growing evidence that connects disruptions in the gut microbiome, the complete collection of bacteria, viruses, and fungi that live in our gastrointestinal system, to ME/CFS.

“The microbiome has emerged as a potential contributor to ME/CFS. These findings provide unique insights into the role the microbiome plays in the disease and suggest that certain differences in gut microbes could serve as biomarkers for ME/CFS,” said Vicky Whittemore, Ph.D., program director at NIH’s National Institute of Neurological Disorders and Stroke (NINDS).

ME/CFS is a serious, chronic, and debilitating disease characterized by a range of symptoms, including fatigue, post-exertional malaise, sleep disturbance, cognitive difficulties, pain, and gastrointestinal issues. The causes of the disease are unknown and there are no treatments.

In one study, senior author Brent L. Williams, Ph.D., assistant professor, W. Ian Lipkin, M.D., John Snow Professor of Epidemiology and director of the Center for Infection and Immunity at the Columbia University Mailman School of Public Health, in New York City, and their collaborators analyzed the genetic makeup of gut bacteria in fecal samples collected from a geographically diverse cohort of 106 people with ME/CFS and 91 healthy controls. The results revealed key differences in microbiome diversity, quantity, metabolic pathways, and interactions between species of gut bacteria.

Dr. Williams and his colleagues found that people with ME/CFS had abnormally low levels of several bacterial species compared to healthy controls, including Faecalibacterium prausnitzii (F. prausnitzii) and Eubacterium rectale. These health-promoting bacteria produce a short chain fatty acid called butyrate, a bacterial metabolite, or by-product, that plays an important role in maintaining gut health. An acetate-producing bacterium was also reduced in samples obtained from people with ME/CFS.

More detailed metabolomic analyses confirmed that a reduction in these bacteria was associated with reduced butyrate production in ME/CFS. Butyrate is the primary energy source for cells that line the gut, providing up to 70% of their energy requirements, support for the gut immune system, and protection against diseases of the digestive tract. Butyrate, tryptophan, and other metabolites detected in the blood are important for regulating immune, metabolic, and endocrine functions.

While species of butyrate-producing bacteria decreased, there were increased levels of nine other species in ME/CFS, including Enterocloster bolteae and Ruminococcus gnavus, which are associated with autoimmune diseases and inflammatory bowel disease, respectively.

Dr. Williams’ group also reported that an abundance of F. prausnitzii was inversely associated with fatigue severity in ME/CFS, suggesting a possible link between gut bacteria and disease symptoms. More research is needed to determine if differences in the gut microbiome are a consequence or cause of symptoms.

The findings indicate that imbalances in these 12 species of bacteria could be used as biomarkers for ME/CFS classification, potentially providing consistent, measurable targets to improve diagnosis.

The gut microbiome is an ecosystem with complex interactions between bacteria, where microbes can exchange or compete for nutrients, metabolites, or other molecular signals. Researchers found notable differences in the network of species interactions in people with ME/CFS—including unique interactions between F. prausnitzii and other species. This indicates that there is an extensive rewiring of bacterial networks in ME/CFS.

“In addition to differences in individual species in ME/CFS, focusing a lens on community interaction dynamics may add greater specificity to the broad definition of dysbiosis, distinguishing between other diseases in which the gut microbiome becomes imbalanced,” said Dr. Williams. “This is also important for generating new testable hypotheses about the underlying mechanisms and mediators of dysbiosis in ME/CFS and may eventually inform strategies to correct these imbalances.”

A balanced microbiome is also essential for a variety of neural systems, especially immune regulation and coupling between energy metabolism and blood supply in the brain, as well as the function of the nerves that supply the gut.

In another study at the Jackson Laboratory in Farmington, Connecticut, Julia Oh, Ph.D.(link is external), associate professor, and Derya Unutmaz, M.D., professor, teamed up with other ME/CFS experts to study microbiome abnormalities in different phases of ME/CFS. Dr. Oh’s team collected and analyzed clinical data, fecal samples, and blood samples from 149 people with ME/CFS who had been diagnosed within the previous four years (74 short-term) or who had been diagnosed more than 10 years ago (75 long-term) and 79 healthy controls.

The results showed that the short-term group had less microbial diversity, while the long-term group established a stable, but individualized gut microbiome similar to healthy controls. Dr. Oh and her colleagues found lower levels of several butyrate-producing species, including F. prausnitzii, especially in the short-term participants. There was also a reduction in species associated with tryptophan metabolism in all ME/CFS participants compared to controls.

Dr. Oh’s group also collected detailed clinical and lifestyle data from participants. By combining these data with genetic and metabolome data, the team developed a way to accurately classify and differentiate ME/CFS from healthy controls. Using this approach, they found that individuals with long-term ME/CFS had a more balanced microbiome but showed more severe clinical symptoms and progressive metabolic irregularities compared to the other groups.

Both studies identify potential biomarkers for ME/CFS, which may inform diagnostic tests and disease classification. Understanding the connection between disturbances in the gut microbiome and ME/CFS may also guide the development of new therapeutics.

Additional research is required to learn more about the pathophysiological implications of butyrate and other metabolite deficiencies in ME/CFS. Future studies will determine how gut microbe disturbances contribute to symptoms, including changes during disease progression.

The studies were funded in part by the NIH’s ME/CFS Collaborative Research Network(link is external), a consortium supported by multiple institutes and centers at NIH, consisting of three collaborative research centers and a data management coordinating center. The research network was established in 2017 to help advance research on ME/CFS. The research was supported by NINDS grant U54NS105539, National Institute of Allergy and Infectious Diseases grants U54AI138370 and R56AI120724, and anonymous donors through the Crowdfunding Microbe Discovery Project.

SARS-CoV-2 infection and persistence in the human body and brain at autopsy

Abstract:

Coronavirus disease 2019 (COVID-19) is known to cause multi-organ dysfunction1-3 during acute infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with some patients experiencing prolonged symptoms, termed post-acute sequelae of SARS-CoV-2 (refs. 4,5). However, the burden of infection outside the respiratory tract and time to viral clearance are not well characterized, particularly in the brain3,6-14.

Here we carried out complete autopsies on 44 patients who died with COVID-19, with extensive sampling of the central nervous system in 11 of these patients, to map and quantify the distribution, replication and cell-type specificity of SARS-CoV-2 across the human body, including the brain, from acute infection to more than seven months following symptom onset.

We show that SARS-CoV-2 is widely distributed, predominantly among patients who died with severe COVID-19, and that virus replication is present in multiple respiratory and non-respiratory tissues, including the brain, early in infection. Further, we detected persistent SARS-CoV-2 RNA in multiple anatomic sites, including throughout the brain, as late as 230 days following symptom onset in one case. Despite extensive distribution of SARS-CoV-2 RNA throughout the body, we observed little evidence of inflammation or direct viral cytopathology outside the respiratory tract.

Our data indicate that in some patients SARS-CoV-2 can cause systemic infection and persist in the body for months.

Source: Stein SR, Ramelli SC, Grazioli A, Chung JY, Singh M, Yinda CK, Winkler CW, Sun J, Dickey JM, Ylaya K, Ko SH, Platt AP, Burbelo PD, Quezado M, Pittaluga S, Purcell M, Munster VJ, Belinky F, Ramos-Benitez MJ, Boritz EA, Lach IA, Herr DL, Rabin J, Saharia KK, Madathil RJ, Tabatabai A, Soherwardi S, McCurdy MT; NIH COVID-19 Autopsy Consortium; Peterson KE, Cohen JI, de Wit E, Vannella KM, Hewitt SM, Kleiner DE, Chertow DS. SARS-CoV-2 infection and persistence in the human body and brain at autopsy. Nature. 2022 Dec;612(7941):758-763. doi: 10.1038/s41586-022-05542-y. Epub 2022 Dec 14. PMID: 36517603; PMCID: PMC9749650. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9749650/ (Full text)

Persistent SARS-CoV-2 infection in patients seemingly recovered from COVID-19

Abstract:

SARS-CoV-2 infection is clinically heterogeneous, ranging from asymptomatic to deadly. A few patients with COVID-19 appear to recover from acute viral infection but nevertheless progress in their disease and eventually die, despite persistent negativity at molecular tests for SARS-CoV-2 RNA.

Here, we performed post-mortem analyses in 27 consecutive patients who had apparently recovered from COVID-19 but had progressively worsened in their clinical conditions despite repeated viral negativity in nasopharyngeal swabs or bronchioalveolar lavage for 11-300 consecutive days (average: 105.5 days). Three of these patients remained PCR-negative for over 9 months.

Post-mortem analysis revealed evidence of diffuse or focal interstitial pneumonia in 23/27 (81%) patients, accompanied by extensive fibrotic substitution in 13 cases (47%). Despite apparent virological remission, lung pathology was similar to that observed in acute COVID-19 individuals, including micro- and macro-vascular thrombosis (67% of cases), vasculitis (24%), squamous metaplasia of the respiratory epithelium (30%), frequent cytological abnormalities and syncytia (67%), and the presence of dysmorphic features in the bronchial cartilage (44%).

Consistent with molecular test negativity, SARS-CoV-2 antigens were not detected in the respiratory epithelium. In contrast, antibodies against both spike and nucleocapsid revealed the frequent (70%) infection of bronchial cartilage chondrocytes and para-bronchial gland epithelial cells. In a few patients (19%), we also detected positivity in vascular pericytes and endothelial cells. Quantitative RT-PCR amplification in tissue lysates confirmed the presence of viral RNA.

Together, these findings indicate that SARS-CoV-2 infection can persist significantly longer than suggested by standard PCR-negative tests, with specific infection of specific cell types in the lung. Whether these persistently infected cells also play a pathogenic role in long COVID remains to be addressed.

Source: Bussani R, Zentilin L, Correa R, Colliva A, Silvestri F, Zacchigna S, Collesi C, Giacca M. Persistent SARS-CoV-2 infection in patients seemingly recovered from COVID-19. J Pathol. 2023 Jan 18. doi: 10.1002/path.6035. Epub ahead of print. PMID: 36651103. https://onlinelibrary.wiley.com/doi/10.1002/path.6035 (Full text)

Long Covid and Neurodegenerative Disease

Abstract:

Brain fog with compromised ability to concentrate has been the most frequent Long Covid (LC) complaint. This is due to an increased TGF beta/IFN gamma with consequently increased bradykinin (BKN), especially in Caucasian females. Brain and lung blood vessels “leak.” This same ratio is increased in Alzheimer’s disease (AD), but decreased in Parkinson’s disease (PD), because CD4+ and CD8+ T cells are differentially affected by the invading associated viruses, e.g., SARS CoV2, HIV, ….

In Covid-19 CD147 receptors on immune cells are critical in generating the increased TGF beta/IFN gamma and those on endothelial cells, platelets, and erythrocytes are critical to the abnormal microvascular blood flow. ACE2 receptors on pneumocytes and enterocytes enable pulmonary and GI entry, initiating gut dysbiosis.

Epigenetics, methylation, magnesium, vitamin D, the B vitamins, and antioxidants suggest that these issues can be surmounted. Biochemical, physiologic, and epidemiologic data are analyzed to answer these questions. An LC model is presented and discussed in the context of the most recent research. Suggestions to avoid these and other worrisome concerns are included. Other topics discussed include estrogen, the gut microbiome, type 2 diabetes (T2D), and homocysteine.

Source: Chambers, P. Long Covid and Neurodegenerative Disease. Preprints 2023, 2023020027 (doi: 10.20944/preprints202302.0027.v1) https://www.preprints.org/manuscript/202302.0027/v1 (Full text available as PDF file)

 

Long COVID Syndrome and Cardiovascular Manifestations: A Systematic Review and Meta-Analysis

Abstract:

Background: Long COVID syndrome is a significant cause of morbidity in COVID-19 patients who remain symptomatic with varied clinical presentations beyond three weeks. Furthermore, the relevance of considering cardiovascular outcomes in post-COVID-19 syndrome is important in the current COVID-19 pandemic.
Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed for this systematic review and meta-analysis. Systematic searches were conducted from multiple databases without language restrictions until October 8, 2022, to find studies evaluating cardiovascular outcomes such as arrhythmias, myocardium and pericardium diseases, coronary vessel disease, and thromboembolic disorders in post-COVID cases. The pooled odds ratio (OR), and standard mean difference (SMD) with their corresponding 95% confidence intervals (CI) were computed to find the association.
Results: Altogether, seven studies with a total of 8,126,462 (cases: 1,321,305; controls: 6,805,157) participants were included in the meta-analysis. Pooled odds ratios of cardiovascular outcomes were significantly higher in post-COVID cases (OR > 1, p < 0.05) than in controls. However, the mortality (OR: 4.76, p = 0.13), and heart rate variability (SMD: −0.06, p = 0.91) between cases and controls were not statistically significant.
Conclusions: Significant cardiovascular sequelae in long COVID syndrome highlight the importance of careful cardiac monitoring of COVID-19 patients in the post-COVID phase to address cardiovascular complications as soon as possible; larger-scale prospective studies are required for accurate estimation.
Source: Shrestha AB, Mehta A, Pokharel P, Mishra A, Adhikari L, Shrestha S, Yadav RS, Khanal S, Sah R, Nowrouzi-Kia B, Padhi BK, Chattu VK. Long COVID Syndrome and Cardiovascular Manifestations: A Systematic Review and Meta-Analysis. Diagnostics. 2023; 13(3):491. https://doi.org/10.3390/diagnostics13030491 https://www.mdpi.com/2075-4418/13/3/491 (Full text)

Compounding for the Treatment of COVID-19 and Long COVID, Part 1: Terminology, Mutations, and Variants

Abstract:

COVID-19 (coronavirus disease 2019), which is caused by the positive-stranded ribonucleic acid virus SARS-CoV-2 (acute respiratory syndrome coronavirus 2), is an extremely contagious airborne illness of pandemic proportions. In the modern era, few diseases other than COVID-19 have produced such severe, prolific, and protean short-term adverse effects and long-term sequelae. In addition, few other pandemics have exhibited a trajectory of morbidity and mortality so affected by social, economic, and political factors as well as individual personal perceptions and beliefs.

Vaccines for the prevention of SARS-CoV-2 infection and treatments for COVID-19 mitigate associated morbidity and mortality, but an increasing array of variants presents challenges to therapeutic effectiveness. As a result, afflicted patients often require customized treatments that address the severity of their infection, the manifestations of disease they exhibit, and their individual pharmacogenomic profile. In such cases, a compounded preparation may offer needed support for recovery.

This article, which is the first in a series on compounding for COVID-19 and long COVID (i.e., the long- term sequelae of SARS-CoV-2 infection), provides information about pertinent viral terminology and a brief overview of SARS-CoV-2 mutations and variants of note. Two formulations for customized compounds that may prove effective in treating the acute and/or long-term effects of COVID-19 when commercial therapies have failed are also provided.

Source: Riepl M. Compounding for the Treatment of COVID-19 and Long COVID, Part 1: Terminology, Mutations, and Variants. Int J Pharm Compd. 2023 Jan-Feb;27(1):12-21. PMID: 36720058. https://pubmed.ncbi.nlm.nih.gov/36720058/

Marital status and post-COVID-19 conditions

Abstract:

Although studies have investigated the factors associated with psychological post-COVID-19 symptoms, the impact of marital status on symptom development has not been fully determined. This study conducts a questionnaire survey to investigate the association between marital status and the proportion of patients with post-COVID-19 symptoms in 749 cases as valid responses.

Depressive state and memory impairment were more frequently seen in the no-spouse group when each symptom was compared according to marital status. Particularly in individuals in the 40s who had minor COVID-19 illness, this trend was noted. Single patients with mild COVID-19 illness may need proactive psychological support.

Source: Kudoh R, Komiya K, Shinohara A, Kageyama T, Hiramatsu K, Kadota JI. Marital status and post-COVID-19 conditions. Respir Investig. 2023 Jan 23;61(2):181-185. doi: 10.1016/j.resinv.2023.01.001. Epub ahead of print. PMID: 36720183; PMCID: PMC9868354. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9868354/ (Full text)

Functional Neurological Disorder in people with Long-Covid: A Systematic Review

Abstract:

Background: Acute health events, including infections, can trigger the onset of functional neurological disorder (FND). We hypothesised that a proportion of people with long-COVID might be experiencing functional symptoms.

Methods: We performed a systematic review of studies containing original data on long-COVID. We reviewed the frequency and characteristics of neurological symptoms, looking for positive evidence suggesting an underlying functional disorder, and the hypothesised causes of long-COVID.

Results: We included 102 studies in our narrative synthesis. The most consistently reported neurological symptoms were cognitive difficulties, headaches, pain, dizziness, fatigue, sleep-related symptoms, and ageusia/anosmia. Overall, we found no evidence that any authors had systematically looked for positive features of FND. An exception were three studies describing temporal inconsistency. In general, the neurological symptoms were insufficiently characterised in order to support or refute a diagnosis of FND. Moreover, only 13 studies specifically focussed on long-COVID after mild infection, where the impact of confounders from the general effects of severe illness would be mitigated. Only one study hypothesised that some people with long-COVID might have a functional disorder, and another 8 studies a chronic fatigue syndrome-like response.

Discussion: Neurological symptoms are prevalent in long-COVID, but poorly characterised. We are struck by the similarities between some manifestations of long-COVID and functional disorders triggered by acute illnesses. Unfortunately, the current literature is plagued by confounders, including the mixing of patients with initial mild infection with those with severe acute medical complications. The hypothesis that long-COVID might in part correspond to a functional disorder remains untested.

Source: Teodoro T, Chen J, Gelauff J, Edwards MJ. Functional Neurological Disorder in people with Long-Covid: A Systematic Review. Eur J Neurol. 2023 Jan 31. doi: 10.1111/ene.15721. Epub ahead of print. PMID: 36719069. https://onlinelibrary.wiley.com/doi/10.1111/ene.15721 (Full text available as PDF file)

Comparability of control and comparison groups in studies assessing long COVID

Abstract:

Background: Awareness of long COVID began primarily through media and social media sources, which eventually led to the development of various definitions, based on methodologies of varying quality. We sought to characterize comparison groups in long COVID studies and evaluate comparability of the different groups.

Methods: We searched Embase, Web of Science, and PubMed for original research articles published in high-impact journals. We included studies on human patients with long COVID outcomes, and we abstracted study-related characteristics, as well as long COVID characteristics.

Results: Of the 83 studies, 3 were RCTs testing interventions for long COVID, and 80 (96.4%) were observational studies. Among the 80 observational studies, 76 (95%) were trying to understand the incidence, prevalence, and risk factors for long COVID, two (2.5%) examined prevention strategies, and 2 (2.5%) examined treatment strategies. Among those 80 studies, 45 (56.2%) utilized a control or comparison group and 35 (43.8%) did not. Compared to 95% of observational studies that documented symptoms or assessed risk factors, all randomized studies assessed treatment strategies. We found 48.8% of observational studies did any adjustment for covariates, including demographics or health status. Of those that did adjust for covariates, 15 (38.5%) adjusted for four or fewer variables. We found that 26.5% of all studies and 45.8% of studies with a control/comparator group matched participants on at least one variable.

Conclusion: Long COVID studies in high-impact journals primarily examine symptoms and risk factors of long COVID, often lack an adequate comparison group, and often do not control for potential confounders. Our results suggest that standardized definitions for long COVID, which are often based on data from uncontrolled and potentially biased studies, should be reviewed to ensure that they are based on objective data.

Source: Haslam A, Prasad V. Comparability of control and comparison groups in studies assessing long COVID. Am J Med. 2023 Jan 25:S0002-9343(23)00038-4. doi: 10.1016/j.amjmed.2023.01.005. Epub ahead of print. PMID: 36708796. https://pubmed.ncbi.nlm.nih.gov/36708796/