inflammation – American ME and CFS Society

Dysregulation of tetrahydrobiopterin metabolism in myalgic encephalomyelitis/chronic fatigue syndrome by pentose phosphate pathway

Abstract:

Background: Tetrahydrobiopterin (BH4) and its oxidized derivative dihydrobiopterin (BH2) were found to be strongly elevated in ME/CFS patients with orthostatic intolerance (ME + OI).

Objective: However, the molecular mechanism of biopterin biogenesis is poorly understood in ME + OI subjects. Here, we report that the activation of the non-oxidative pentose phosphate pathway (PPP) plays a critical role in the biogenesis of biopterins (BH4 and BH2) in ME + OI subjects.

Research design and results: Microarray-based gene screening followed by real-time PCR-based validation, ELISA assay, and finally enzyme kinetic studies of glucose-6-phosphate dehydrogenase (G6PDH), transaldolase (TALDO1), and transketolase (TK) enzymes revealed that the augmentation of anaerobic PPP is critical in the regulations of biopterins. To further investigate, we devised a novel cell culture strategy to induce non-oxidative PPP by treating human microglial cells with ribose-5-phosphate (R5P) under a hypoxic condition of 85%N₂/10%CO₂/5%O₂ followed by the analysis of biopterin metabolism via ELISA, immunoblot, and dual immunocytochemical analyses. Moreover, the siRNA knocking down of the taldo1 gene strongly inhibited the bioavailability of phosphoribosyl pyrophosphate (PRPP), reduced the expressions of purine biosynthetic enzymes, attenuated GTP cyclohydrolase 1 (GTPCH1), and suppressed subsequent production of BH4 and its metabolic conversion to BH2 in R5P-treated and hypoxia-induced C20 human microglia cells. These results confirmed that the activation of non-oxidative PPP is indeed required for the upregulation of both BH4 and BH2 via the purine biosynthetic pathway. To test the functional role of ME + OI plasma-derived biopterins, exogenously added plasma samples of ME + OI plasma with high BH4 upregulated inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in human microglial cells indicating that the non-oxidative PPP-induced-biopterins could stimulate inflammatory response in ME + OI patients.

Conclusion: Taken together, our current research highlights that the induction of non-oxidative PPP regulates the biogenesis of biopterins contributing to ME/CFS pathogenesis.

Source: Bulbule S, Gottschalk CG, Drosen ME, Peterson D, Arnold LA, Roy A. Dysregulation of tetrahydrobiopterin metabolism in myalgic encephalomyelitis/chronic fatigue syndrome by pentose phosphate pathway. J Cent Nerv Syst Dis. 2024 Aug 19;16:11795735241271675. doi: 10.1177/11795735241271675. PMID: 39161795; PMCID: PMC11331476. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11331476/ (Full text)

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: the biology of a neglected disease

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic, debilitating disease characterised by a wide range of symptoms that severely impact all aspects of life. Despite its significant prevalence, ME/CFS remains one of the most understudied and misunderstood conditions in modern medicine. ME/CFS lacks standardised diagnostic criteria owing to variations in both inclusion and exclusion criteria across different diagnostic guidelines, and furthermore, there are currently no effective treatments available.

Moving beyond the traditional fragmented perspectives that have limited our understanding and management of the disease, our analysis of current information on ME/CFS represents a significant paradigm shift by synthesising the disease’s multifactorial origins into a cohesive model. We discuss how ME/CFS emerges from an intricate web of genetic vulnerabilities and environmental triggers, notably viral infections, leading to a complex series of pathological responses including immune dysregulation, chronic inflammation, gut dysbiosis, and metabolic disturbances.

This comprehensive model not only advances our understanding of ME/CFS’s pathophysiology but also opens new avenues for research and potential therapeutic strategies. By integrating these disparate elements, our work emphasises the necessity of a holistic approach to diagnosing, researching, and treating ME/CFS, urging the scientific community to reconsider the disease’s complexity and the multifaceted approach required for its study and management.

Source: Arron HE, Marsh BD, Kell DB, Khan MA, Jaeger BR, Pretorius E. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: the biology of a neglected disease. Front Immunol. 2024 Jun 3;15:1386607. doi: 10.3389/fimmu.2024.1386607. PMID: 38887284; PMCID: PMC11180809. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11180809/ (Full text)

An amyloidogenic fragment of the SARS CoV-2 envelope protein promotes serum amyloid A misfolding and fibrillization

Abstract:

SARS CoV-2 infection can affect a surprising number of organs in the body and cause symptoms such as abnormal blood coagulation, fibrinolytic disturbances, and neurodegeneration. Our study delves into the intricate pathogenic potential of a SARS-CoV-2 envelope protein peptide, shedding light on its implications for multi-organ effects and amyloid formation. Specifically, we focus on the peptide SK9 or 54SFYVYSRVK62 derived from the C-terminus of human SARS coronavirus 2 envelope protein.

We demonstrate that SK9 containing peptides readily form classic amyloid structures consistent with predictions of amyloid aggregation algorithms. In vivo, overexpression of proteases such as neutrophil elastase during inflammation can potentially lead to C-terminal peptides containing SK9. We also demonstrate that SK9 can promote the fibrillization of SAA, a protein marker of acute inflammation.

Our investigations reveal that the aromatic residues Phe2 and Tyr3 of SK9 play a pivotal role in its amyloidogenic function. We show that the primary sites of SK9-SAA binding lie in the amyloidogenic hotspots of SAA itself. Our results highlight two possible complications of SARS CoV-2 infection in individuals with hyper-inflammation either due to amyloids arising from SK9 containing peptides or SK9-induced AA amyloidosis.

Source: Asal Nady, Sean E. Reichheld, Simon Sharpe. An amyloidogenic fragment of the SARS CoV-2 envelope protein promotes serum amyloid A misfolding and fibrillization. bioRxiv 2024.04.25.591137; doi: https://doi.org/10.1101/2024.04.25.591137 https://www.biorxiv.org/content/10.1101/2024.04.25.591137v1.full (Full text)

Large-scale phenotyping of patients with long COVID post-hospitalization reveals mechanistic subtypes of disease

Abstract:

One in ten severe acute respiratory syndrome coronavirus 2 infections result in prolonged symptoms termed long coronavirus disease (COVID), yet disease phenotypes and mechanisms are poorly understood¹. Here we profiled 368 plasma proteins in 657 participants ≥3 months following hospitalization. Of these, 426 had at least one long COVID symptom and 233 had fully recovered.

Elevated markers of myeloid inflammation and complement activation were associated with long COVID. IL-1R2, MATN2 and COLEC12 were associated with cardiorespiratory symptoms, fatigue and anxiety/depression; MATN2, CSF3 and C1QA were elevated in gastrointestinal symptoms and C1QA was elevated in cognitive impairment. Additional markers of alterations in nerve tissue repair (SPON-1 and NFASC) were elevated in those with cognitive impairment and SCG3, suggestive of brain-gut axis disturbance, was elevated in gastrointestinal symptoms.

Severe acute respiratory syndrome coronavirus 2-specific immunoglobulin G (IgG) was persistently elevated in some individuals with long COVID, but virus was not detected in sputum. Analysis of inflammatory markers in nasal fluids showed no association with symptoms.

Our study aimed to understand inflammatory processes that underlie long COVID and was not designed for biomarker discovery. Our findings suggest that specific inflammatory pathways related to tissue damage are implicated in subtypes of long COVID, which might be targeted in future therapeutic trials.

Source: Liew F, Efstathiou C, Fontanella S, Richardson M, Saunders R, Swieboda D, Sidhu JK, Ascough S, Moore SC, Mohamed N, Nunag J, King C, Leavy OC, Elneima O, McAuley HJC, Shikotra A, Singapuri A, Sereno M, Harris VC, Houchen-Wolloff L, Greening NJ, Lone NI, Thorpe M, Thompson AAR, Rowland-Jones SL, Docherty AB, Chalmers JD, Ho LP, Horsley A, Raman B, Poinasamy K, Marks M, Kon OM, Howard LS, Wootton DG, Quint JK, de Silva TI, Ho A, Chiu C, Harrison EM, Greenhalf W, Baillie JK, Semple MG, Turtle L, Evans RA, Wain LV, Brightling C, Thwaites RS, Openshaw PJM; PHOSP-COVID collaborative group; ISARIC investigators. Large-scale phenotyping of patients with long COVID post-hospitalization reveals mechanistic subtypes of disease. Nat Immunol. 2024 Apr;25(4):607-621. doi: 10.1038/s41590-024-01778-0. Epub 2024 Apr 8. PMID: 38589621; PMCID: PMC11003868. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11003868/ (Full text)

ACE-2-like enzymatic activity is associated with immunoglobulin in COVID-19 patients

Abstract:

Many mechanisms responsible for COVID-19 pathogenesis are well-established, but COVID-19 includes features with unclear pathogenesis, such as autonomic dysregulation, coagulopathies, and high levels of inflammation. The receptor for the SARS-CoV-2 spike protein receptor-binding domain (RBD) is angiotensin-converting enzyme 2 (ACE2). We hypothesized that some COVID-19 patients may develop antibodies that have a negative molecular image of RBD sufficiently similar to ACE2 to yield ACE2-like catalytic activity-ACE2-like abzymes.

To explore this hypothesis, we studied patients hospitalized with COVID-19 who had plasma samples available obtained about 7 days after admission. ACE2 is a metalloprotease that requires Zn²⁺ for activity. However, we found that the plasma from some patients studied could specifically cleave a synthetic ACE2 peptide substrate, even though the plasma samples were collected using disodium EDTA anticoagulant. When we spiked plasma with synthetic ACE2, no ACE2 substrate cleavage activity was observed unless Zn²⁺ was added or the plasma was diluted to decrease EDTA concentration.

After processing samples by 100 kDa size exclusion columns and protein A/G adsorption, which depleted immunoglobulin by >99.99%, the plasma samples did not cleave the ACE2 substrate peptide. The data suggest that some patients with COVID-19 develop antibodies with abzyme-like activity capable of cleaving synthetic ACE2 substrate. Since abzymes can exhibit promiscuous substrate specificities compared to the enzyme whose active site image they resemble, and since proteolytic cascades regulate many physiologic processes, anti-RBD abzymes may contribute to some otherwise obscure COVID-19 pathogenesis.

Importance: We provide what we believe to be the first description of angiotensin-converting enzyme 2 (ACE2)-like enzymatic activity associated with immunoglobulin in COVID-19 patients. COVID-19 includes many puzzling clinical features that have unclear pathogenesis, including a hyperinflammatory state, abnormalities of the clotting cascade, and blood pressure instability.

We hypothesized that some patients with COVID-19 patients may produce antibodies against SARS-CoV-2 with enzymatic activity, or abzymes, that target important proteolytic regulatory cascades. The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein binds ACE2 on the surface of the future host cell. This means that the RBD has a negative molecular image of ACE2.

We hypothesized that some antibodies produced against the RBD would have, in turn, a negative molecular image of the RBD sufficiently similar to ACE2 to have ACE2-like catalytic activity. In other words, some anti-RBD antibodies would be ACE2-like abzymes. Abzymes elicited by SARS-CoV-2 infection have the potential to affect host physiology.

Source: Song Y, Myers R, Mehl F, Murphy L, Brooks B, Wilson JM, Kadl A, Woodfolk J, Zeichner SL. ACE-2-like enzymatic activity is associated with immunoglobulin in COVID-19 patients. mBio. 2024 Mar 19:e0054124. doi: 10.1128/mbio.00541-24. Epub ahead of print. PMID: 38501835. https://journals.asm.org/doi/10.1128/mbio.00541-24 (Full text)

Bulk RNA sequencing for analysis of post COVID-19 condition in adolescents and young adults

Abstract:

Background: Post COVID-19 condition (PCC) is a complication of SARS-COV-2 infection and can lead to long-term disability.

Methods: The present study was designed to analyse the gene expression patterns of PCC through bulk RNA sequencing of whole blood and to explore the potential molecular mechanisms of PCC. Whole blood was collected from 80 participants enrolled in a prospective cohort study following SARS-CoV-2 infected and non-infected individuals for 6 months after recruitment and was used for bulk RNA sequencing. Identification of differentially expressed genes (DEG), pathway enrichment and immune cell deconvolution was performed to explore potential biological pathways involved in PCC.

Results: We have found 13 differentially expressed genes associated with PCC. Enriched pathways were related to interferon-signalling and anti-viral immune processes.

Conclusion: The PCC transcriptome is characterized by a modest overexpression of interferon-stimulated genes, pointing to a subtle ongoing inflammatory response.

Source: Sommen SL, Zhao Z, Segtnan S, Stiansen-Sonerud T, Selvakumar J, Beier Havdal L, Gjerstad J, Wyller VBB, Lund Berven L. Bulk RNA sequencing for analysis of post COVID-19 condition in adolescents and young adults. J Transl Med. 2024 Mar 26;22(1):312. doi: 10.1186/s12967-024-05117-7. PMID: 38532465. https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-024-05117-7 (Full text)

Iron dysregulation and inflammatory stress erythropoiesis associates with long-term outcome of COVID-19

Abstract:

Persistent symptoms following SARS-CoV-2 infection are increasingly reported, although the drivers of post-acute sequelae (PASC) of COVID-19 are unclear. Here we assessed 214 individuals infected with SARS-CoV-2, with varying disease severity, for one year from COVID-19 symptom onset to determine the early correlates of PASC.

A multivariate signature detected beyond two weeks of disease, encompassing unresolving inflammation, anemia, low serum iron, altered iron-homeostasis gene expression and emerging stress erythropoiesis; differentiated those who reported PASC months later, irrespective of COVID-19 severity. A whole-blood heme-metabolism signature, enriched in hospitalized patients at month 1-3 post onset, coincided with pronounced iron-deficient reticulocytosis. Lymphopenia and low numbers of dendritic cells persisted in those with PASC, and single-cell analysis reported iron maldistribution, suggesting monocyte iron loading and increased iron demand in proliferating lymphocytes.

Thus, defects in iron homeostasis, dysregulated erythropoiesis and immune dysfunction due to COVID-19 possibly contribute to inefficient oxygen transport, inflammatory disequilibrium and persisting symptomatology, and may be therapeutically tractable.

Source: Hanson AL, Mulè MP, Ruffieux H, Mescia F, Bergamaschi L, Pelly VS, Turner L, Kotagiri P; Cambridge Institute of Therapeutic Immunology and Infectious Disease–National Institute for Health Research (CITIID–NIHR) COVID BioResource Collaboration; Göttgens B, Hess C, Gleadall N, Bradley JR, Nathan JA, Lyons PA, Drakesmith H, Smith KGC. Iron dysregulation and inflammatory stress erythropoiesis associates with long-term outcome of COVID-19. Nat Immunol. 2024 Mar;25(3):471-482. doi: 10.1038/s41590-024-01754-8. Epub 2024 Mar 1. PMID: 38429458; PMCID: PMC10907301. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10907301/ (Full text)

Severe COVID-19 and long COVID are associated with high expression of STING, cGAS and IFN-α

Abstract:

The cGAS-STING pathway appears to contribute to dysregulated inflammation during coronavirus disease 2019 (COVID-19); however, inflammatory factors related to long COVID are still being investigated.

In the present study, we evaluated the association of cGAS and STING gene expression levels and plasma IFN-α, TNF-α and IL-6 levels with COVID-19 severity in acute infection and long COVID, based on analysis of blood samples from 148 individuals, 87 with acute COVID-19 and 61 in the post-COVID-19 period.

Quantification of gene expression was performed by real-time PCR, and cytokine levels were quantified by ELISA and flow cytometry. In acute COVID-19, cGAS, STING, IFN-α, TNF-α, and IL-6 levels were higher in patients with severe disease than in those with nonsevere manifestations (p < 0.05). Long COVID was associated with elevated cGAS, STING and IFN-α levels (p < 0.05).

Activation of the cGAS-STING pathway may contribute to an intense systemic inflammatory state in severe COVID-19 and, after infection resolution, induce an autoinflammatory disease in some tissues, resulting in long COVID.

Source: Queiroz, M.A.F., Brito, W.R.S., Pereira, K.A.S. et al. Severe COVID-19 and long COVID are associated with high expression of STING, cGAS and IFN-α. Sci Rep 14, 4974 (2024). https://doi.org/10.1038/s41598-024-55696-0 https://www.nature.com/articles/s41598-024-55696-0 (Full text)

Patients with ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome) and chronic pain report similar level of sickness behavior as individuals injected with bacterial endotoxin at peak inflammation

Abstract:

Background: Chronic sickness behavior is implicated in ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome) and chronic pain but the level of subjective sickness behavior in these conditions has not been investigated or compared to other clinical and non-clinical samples, or to the level in experimental inflammation. Furthermore, the relationship between sickness behavior and self-rated health and functioning is not known in patients with ME/CFS and chronic pain. The aim of the present study was to investigate how sickness behavior in patients with chronic conditions differs from that in individuals with experimental acute sickness, primary care patients, the general population and healthy subjects. In addition, we wanted to explore how sickness behavior is related to self-rated health and health-related functioning.

Methods: Sickness behavior was quantified using the sickness questionnaire (SicknessQ). Self-ratings were collected at one time-point in 6 different samples. Levels of sickness behavior in patients with ME/CFS (n = 38) and patients with chronic pain (n = 190) were compared to healthy subjects with lipopolysaccharide(LPS)-induced inflammation (n = 29), primary care patients (n = 163), individuals from the general population (n = 155) and healthy subjects (n = 48), using linear regression. Correlations and moderated regression analyses were used to investigate associations between sickness behavior and self-rated health and health-related functioning in ME/CFS, chronic pain and the general population.

Results: LPS-injected individuals (M = 16.3), patients with ME/CFS (M = 16.1), chronic pain (M = 16.1) and primary care patients (M = 10.7) reported significantly higher SicknessQ scores than individuals from the general population (M = 5.4) and healthy subjects (M = 3.6) all p‘s < 0.001). In turn, LPS-injected individuals, patients with ME/CFS and chronic pain reported significantly higher SicknessQ scores than primary care patients (p’s < 0.01). Higher levels of sickness behavior were associated with poorer self-rated health and health-related functioning (p’s < 0.01), but less so in patients with ME/CFS and chronic pain than in individuals from the general population.

Conclusions: Patients with ME/CFS and chronic pain report similar high levels of sickness behavior; higher than primary care patients, and comparable to levels in experimental inflammation. Further study of sickness behavior in ME/CFS and chronic pain populations is warranted as immune-to-brain interactions and sickness behavior may be of importance for functioning as well as in core pathophysiological processes in subsets of patients.

Source: Jonsjö MA, Åström J, Jones MP, Karshikoff B, Lodin K, Holmström L, Agréus L, Wicksell RK, Axelsson J, Lekander M, Olsson GL, Kemani M, Andreasson A. Patients with ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome) and chronic pain report similar level of sickness behavior as individuals injected with bacterial endotoxin at peak inflammation. Brain Behav Immun Health. 2019 Dec 17;2:100028. doi: 10.1016/j.bbih.2019.100028. PMID: 38377418; PMCID: PMC8474484. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8474484/ (Full text)

Brain FADE syndrome: the final common pathway of chronic inflammation in neurological disease

Abstract:

Importance: While the understanding of inflammation in the pathogenesis of many neurological diseases is now accepted, this special commentary addresses the need to study chronic inflammation in the propagation of cognitive Fog, Asthenia, and Depression Related to Inflammation which we name Brain FADE syndrome. Patients with Brain FADE syndrome fall in the void between neurology and psychiatry because the depression, fatigue, and fog seen in these patients are not idiopathic, but instead due to organic, inflammation involved in neurological disease initiation.

Observations: A review of randomized clinical trials in stroke, multiple sclerosis, Parkinson’s disease, COVID, traumatic brain injury, and Alzheimer’s disease reveal a paucity of studies with any component of Brain FADE syndrome as a primary endpoint. Furthermore, despite the relatively well-accepted notion that inflammation is a critical driving factor in these disease pathologies, none have connected chronic inflammation to depression, fatigue, or fog despite over half of the patients suffering from them.

Conclusions and relevance: Brain FADE Syndrome is important and prevalent in the neurological diseases we examined. Classical “psychiatric medications” are insufficient to address Brain FADE Syndrome and a novel approach that utilizes sequential targeting of innate and adaptive immune responses should be studied.

Source: Khalid A. Hanafy, Tudor G. Jovin. Brain FADE syndrome: the final common pathway of chronic inflammation in neurological disease. Front. Immunol., 17 January 2024, Sec. Inflammation, Volume 15 – 2024 | https://doi.org/10.3389/fimmu.2024.1332776 https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1332776/full (Full text)