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)

In severe first episode major depressive disorder, psychosomatic, chronic fatigue syndrome, and fibromyalgia symptoms are driven by immune activation and increased immune-associated neurotoxicity.

Abstract:

Background: Major depressive disorder (MDD) is accompanied by activated neuro-immune pathways, increased physiosomatic and chronic fatigue-fibromyalgia (FF) symptoms. The most severe MDD phenotype, namely major dysmood disorder (MDMD), is associated with adverse childhood experiences (ACEs) and negative life events (NLEs) which induce cytokines/chemokines/growth factors.

Aims: To delineate the impact of ACE+NLEs on physiosomatic and FF symptoms in first episode (FE)-MDMD, and examine whether these effects are mediated by immune profiles.

Methods: ACEs, NLEs, physiosomatic and FF symptoms, and 48 cytokines/chemokines/growth factors were measured in 64 FE-MDMD patients and 32 normal controls.

Results: Physiosomatic, FF and gastro-intestinal symptoms belong to the same factor as depression, anxiety, melancholia, and insomnia. The first factor extracted from these seven domains is labeled the physio-affective phenome of depression. A part (59.0%) of the variance in physiosomatic symptoms is explained by the independent effects of interleukin (IL)-16 and IL-8 (positively), CCL3 and IL-1 receptor antagonist (inversely correlated). A part (46.5%) of the variance in physiosomatic (59.0%) symptoms is explained by the independent effects of interleukin (IL)-16, TNF-related apoptosis-inducing ligand (TRAIL) (positively) and combined activities of negative immunoregulatory cytokines (inversely associated).

Partial Least Squares analysis shows that ACE+NLEs exert a substantial influence on the physio-affective phenome which are partly mediated by an immune network composed of interleukin-16, CCL27, TRAIL, macrophage-colony stimulating factor, and stem cell growth factor.

Conclusions: The physiosomatic and FF symptoms of FE-MDMD are partly caused by immuneassociated neurotoxicity due to Th-1 polarization, T helper-1, and M1 macrophage activation and relative lowered compensatory immunoregulatory protection.

Source: Michael Maes, Abbas F Almulla, Bo Zhou, Ali Abbas Abo Algon, Pimpayao Sodsai. In severe first episode major depressive disorder, psychosomatic, chronic fatigue syndrome, and fibromyalgia symptoms are driven by immune activation and increased immune-associated neurotoxicity. ResearchGate [Preprint] https://www.researchgate.net/publication/372940821_In_severe_first_episode_major_depressive_disorder_psychosomatic_chronic_fatigue_syndrome_and_fibromyalgia_symptoms_are_driven_by_immune_activation_and_increased_immune-associated_neurotoxicity (Full text)

In Schizophrenia, Chronic Fatigue Syndrome- and Fibromyalgia-Like Symptoms are Driven by Breakdown of the Paracellular Pathway with Increased Zonulin and Immune Activation-Associated Neurotoxicity

Abstract:

Background: A meaningful part of schizophrenia patients suffer from physiosomatic symptoms (formerly named psychosomatic) which are reminiscent of chronic fatigue syndrome and fibromyalgia (FF) and are associated with signs of immune activation and increased levels of tryptophan catabolites (TRYCATs).

Aims: To examine whether FF symptoms in schizophrenia are associated with breakdown of the paracellular pathway, zonulin, lowered natural IgM responses to oxidative specific epitopes (OSEs); and whether FF symptoms belong to the behavioral-cognitive-physical-psychosocial-(BCPS)-worsening index consisting of indices of a general cognitive decline (G-CoDe), symptomatome of schizophrenia, and quality of life (QoL)-phenomenome.

Methods: FF symptoms were assessed using the Fibromyalgia and Chronic Fatigue Rating scale in 80 schizophrenia patients and 40 healthy controls and serum cytokines/chemokines, IgA levels to TRYCATs, IgM to OSEs, zonulin and transcellular/paracellular (TRANS/PARA) molecules were assayed using ELISA methods.

Results: A large part (42.3%) of the variance in the total FF score was explained by the regression on the PARA/TRANS ratio, pro-inflammatory cytokines, IgM to zonulin, IgA to TRYCATs (all positively) and IgM to OSEs (inversely). There were highly significant correlations between the total FF score and G-CoDe, symtopmatome, QoL phenomenome and BCPS-worsening score. FF symptoms belong to a common core shared by G-CoDe, symtopmatome, and QoL phenomenome.

Discussion: The physio-somatic symptoms of schizophrenia are driven by various pathways including increased zonulin, breakdown of the paracellular tight-junctions pathway, immune activation with induction of the TRYCAT pathway, and consequent neurotoxicity. It is concluded that FF symptoms are part of the phenome of schizophrenia and BCPS-worsening as well.

Source: Maes M, Andrés-Rodríguez L, Vojdani A, Sirivichayakul S, Barbosa DS, Kanchanatawan B. In Schizophrenia, Chronic Fatigue Syndrome- and Fibromyalgia-Like Symptoms are Driven by Breakdown of the Paracellular Pathway with Increased Zonulin and Immune Activation-Associated Neurotoxicity. CNS Neurol Disord Drug Targets. 2022 Aug 6. doi: 10.2174/1871527321666220806100600. Epub ahead of print. PMID: 35946099.

Persistent Autoimmune Activation and Proinflammatory State in Post-COVID Syndrome

Abstract:

Background: The immunopathological pathways enabling post-COVID syndrome (PCS) development are not entirely known. We underwent a longitudinal analysis of patients with COVID-19 who developed PCS aiming to evaluate the autoimmune and immunological status associated with this condition.

Methods: Thirty-three patients were included for longitudinal clinical and autoantibody analyses of whom 12 patients were assessed for cytokines and lymphocyte populations. Patients were followed during 7-11 months after acute COVID-19. Autoimmune profile and immunological status were evaluated mainly by enzyme-linked-immunosorbent assays and flow cytometry.

Results: Latent autoimmunity and overt autoimmunity persisted over time. A proinflammatory state was observed in patients with PCS characterized by upregulated IFN-α, TNF-α, G-CSF, IL-17A, IL-6, IL-1β, and IL-13, whereas IP-10 was decreased. In addition, PCS was characterized by increased levels of Th9, CD8+ effector T cells, naive B cells, and CD4+ effector memory T cells. Total levels of IgG S1-SARS-CoV-2 antibodies remained elevated over time.

Discussion: The clinical manifestations of PCS are associated with the persistence of a proinflammatory, and effector phenotype induced by SARS-CoV-2 infection. This long-term persistent immune activation may contribute to the development of latent and overt autoimmunity. Results suggest the need to evaluate the role of immunomodulation in the treatment of PCS.

Source: Acosta-Ampudia Y, Monsalve DM, Rojas M, Rodríguez Y, Zapata E, Ramírez-Santana C, Anaya JM. Persistent Autoimmune Activation and Proinflammatory State in Post-COVID Syndrome. J Infect Dis. 2022 Jan 25:jiac017. doi: 10.1093/infdis/jiac017. Epub ahead of print. PMID: 35079804. https://pubmed.ncbi.nlm.nih.gov/35079804/

Evaluation of Immune Dysregulation in an Austrian Patient Cohort Suffering from Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a severe multi-systemic disease characterized by debilitating fatigue that is not relieved by rest. The causes of the disease are still largely unexplained, and no causative treatment is currently available. Changes in the immune response are considered as fundamental in the development of ME/CFS. Thus, we aimed to evaluate the immunological profile of ME/CFS patients in a retrospective data analysis.

As part of the routine workup for ME/CFS patients, a differential blood count, leukocyte subtyping, and quantification of immunoglobulins and IgG subclasses, as well as a complement analysis, was performed. Out of 262 ME/CFS patients, 64.9% had a reduction or deficiency in at least one of the listed immune parameters. In contrast, 26.3% showed signs of immune activation or inflammation. A total of 17.6% of the ME/CFS patients had an unclassified antibody deficiency, with IgG3 and IgG4 subclass deficiencies as the most common phenotypes. Reduced MBL (mannose-binding lectin) levels were found in 32% of ME/CFS patients, and MBL deficiency in 7%.

In summary, the present results confirmed the relevance of immune dysfunction in ME/CFS patients underlining the involvement of a dysfunctional immune response in the disease. Thus, immune parameters are relevant disease biomarkers, which might lead to targeted therapeutic approaches in the future.

Source: Lutz L, Rohrhofer J, Zehetmayer S, Stingl M, Untersmayr E. Evaluation of Immune Dysregulation in an Austrian Patient Cohort Suffering from Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Biomolecules. 2021 Sep 14;11(9):1359. doi: 10.3390/biom11091359. PMID: 34572574. https://pubmed.ncbi.nlm.nih.gov/34572574/

Dysregulation of cytokine pathways in chronic fatigue syndrome and multiple sclerosis

Abstract:

Background: Cytokine studies in chronic fatigue syndrome (CFS) have yielded mixed findings.

Purpose: This investigation evaluated whether network analysis of cytokine production differs between patients with CFS and multiple sclerosis (MS) as compared to a reference group of healthy controls.

Methods: Three subgroups (N = 109) were included: 15 participants who met diagnostic criteria for CFS, 57 participants meeting criteria for MS, and 37 controls. Peripheral blood was obtained and production of a select cytokine profile was determined from stimulated and unstimulated mononuclear cells. Data were generated through the use of a multi-analyte bead suspension array. Pairwise associations were determined for each group, and these associations were used to create a graphical representation of the data. The graph was clustered using an eigenvector community algorithm and results visualized using edges to model the correlations by color and thickness to show direction and strength.

Results: The control and MS groups produced a three-neighborhood relationship regardless of cell condition. While producing a three-neighborhood relationship, the MS group differed significantly from the control group as it displayed stronger relationships among pro-inflammatory cytokines. In contrast, the CFS group displayed a three-neighborhood solution when unstimulated. However, when cells from the CFS group were stimulated, a two-neighborhood model was found that exhibited stronger inter-cytokine correlations. The model found in CFS was significantly different from that found in the control and MS groups.

Conclusion: CFS was characterized by a pattern of global immunologic activation using network analysis, fundamentally different from those found for either MS or control groups.

Source: Matthew Sorenson, Jacob Furst, Herbert Mathews & Leonard A. Jason. Dysregulation of cytokine pathways in chronic fatigue syndrome and multiple sclerosis. Fatigue: Biomedicine, Health & Behavior, Published online: 07 Jun 2017. http://www.tandfonline.com/doi/abs/10.1080/21641846.2017.1335237?journalCode=rftg20

Hypothalamic-Pituitary-Adrenal Hypofunction in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS) as a Consequence of Activated Immune-Inflammatory and Oxidative and Nitrosative Pathways

Abstract:

There is evidence that immune-inflammatory and oxidative and nitrosative stress (O&NS) pathways play a role in the pathophysiology of myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS). There is also evidence that these neuroimmune diseases are accompanied by hypothalamic-pituitary-adrenal (HPA) axis hypoactivity as indicated by lowered baseline glucocorticoid levels.

This paper aims to review the bidirectional communications between immune-inflammatory and O&NS pathways and HPA axis hypoactivity in ME/CFS, considering two possibilities: (a) Activation of immune-inflammatory pathways is secondary to HPA axis hypofunction via attenuated negative feedback mechanisms, or (b) chronic activated immune-inflammatory and O&NS pathways play a causative role in HPA axis hypoactivity.

Electronic databases, i.e., PUBMED, Scopus, and Google Scholar, were used as sources for this narrative review by using keywords CFS, ME, cortisol, ACTH, CRH, HPA axis, glucocorticoid receptor, cytokines, immune, immunity, inflammation, and O&NS.

Findings show that activation of immune-inflammatory and O&NS pathways in ME/CFS are probably not secondary to HPA axis hypoactivity and that activation of these pathways may underpin HPA axis hypofunction in ME/CFS. Mechanistic explanations comprise increased levels of tumor necrosis factor-α, T regulatory responses with elevated levels of interleukin-10 and transforming growth factor-β, elevated levels of nitric oxide, and viral/bacterial-mediated mechanisms.

HPA axis hypoactivity in ME/CFS is most likely a consequence and not a cause of a wide variety of activated immune-inflammatory and O&NS pathways in that illness.

 

Source: Morris G, Anderson G, Maes M. Hypothalamic-Pituitary-Adrenal Hypofunction in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS) as a Consequence of Activated Immune-Inflammatory and Oxidative and Nitrosative Pathways. Mol Neurobiol. 2016 Oct 20. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/27766535

 

Activation of cell-mediated immunity in depression: association with inflammation, melancholia, clinical staging and the fatigue and somatic symptom cluster of depression

Abstract:

BACKGROUND: Depression is characterized by activation of cell-mediated immunity (CMI), including increased neopterin levels, and increased pro-inflammatory cytokines (PICs), such as interleukin-1 (IL-1) and tumor necrosis factor-α (TNFα). These PICs may induce depressive, melancholic and chronic fatigue (CF) symptoms.

METHODS: We examined serum neopterin and plasma PIC levels in depressive subgroups in relation to the depressive subtypes and the melancholic and CF symptoms of depression. Participants were 85 patients with depression and in 26 normal controls. Severity of depression was assessed with the Hamilton Depression Rating Scale (HDRS) and severity of CF with the Fibromyalgia and Chronic Fatigue Syndrome (FF) Rating Scale.

RESULTS: Serum neopterin was significantly higher in depressed patients and in particular in those with melancholia. There were positive correlations between serum neopterin, the plasma PICs and the number of previous depressive episodes. Neopterin and TNFα were associated with melancholia, while both PICs were associated with CF. Melancholia-group membership was predicted by the HDRS and neopterin, and CF group membership by age, the FF score and serum TNFα.

DISCUSSION: Depression and melancholia are accompanied by CMI activation, suggesting that neopterin plays a role in their pathophysiology, e.g. through activation of oxidative and nitrosative stress and apoptosis pathways. The intertwined CMI and inflammatory responses are potentially associated with the onset of depression and with the melancholic and CF symptoms of depression. Exposure to previous depressive episodes may magnify the size of CMI and PIC responses, possibly increasing the likelihood of new depressive episodes. CMI activation and inflammation may contribute to the staging or recurrence of depression.

Copyright © 2011 Elsevier Inc. All rights reserved.

 

Source: Maes M, Mihaylova I, Kubera M, Ringel K. Activation of cell-mediated immunity in depression: association with inflammation, melancholia, clinical staging and the fatigue and somatic symptom cluster of depression. Prog Neuropsychopharmacol Biol Psychiatry. 2012 Jan 10;36(1):169-75. doi: 10.1016/j.pnpbp.2011.09.006. Epub 2011 Sep 16. https://www.ncbi.nlm.nih.gov/pubmed/21945535

 

Evidence of inflammatory immune signaling in chronic fatigue syndrome: A pilot study of gene expression in peripheral blood

Abstract:

BACKGROUND: Genomic profiling of peripheral blood reveals altered immunity in chronic fatigue syndrome (CFS) however interpretation remains challenging without immune demographic context. The object of this work is to identify modulation of specific immune functional components and restructuring of co-expression networks characteristic of CFS using the quantitative genomics of peripheral blood.

METHODS: Gene sets were constructed a priori for CD4+ T cells, CD8+ T cells, CD19+ B cells, CD14+ monocytes and CD16+ neutrophils from published data. A group of 111 women were classified using empiric case definition (U.S. Centers for Disease Control and Prevention) and unsupervised latent cluster analysis (LCA). Microarray profiles of peripheral blood were analyzed for expression of leukocyte-specific gene sets and characteristic changes in co-expression identified from topological evaluation of linear correlation networks.

RESULTS: Median expression for a set of 6 genes preferentially up-regulated in CD19+ B cells was significantly lower in CFS (p = 0.01) due mainly to PTPRK and TSPAN3 expression. Although no other gene set was differentially expressed at p < 0.05, patterns of co-expression in each group differed markedly. Significant co-expression of CD14+ monocyte with CD16+ neutrophil (p = 0.01) and CD19+ B cell sets (p = 0.00) characterized CFS and fatigue phenotype groups. Also in CFS was a significant negative correlation between CD8+ and both CD19+ up-regulated (p = 0.02) and NK gene sets (p = 0.08). These patterns were absent in controls.

CONCLUSION: Dissection of blood microarray profiles points to B cell dysfunction with coordinated immune activation supporting persistent inflammation and antibody-mediated NK cell modulation of T cell activity. This has clinical implications as the CD19+ genes identified could provide robust and biologically meaningful basis for the early detection and unambiguous phenotyping of CFS.

 

Source: Aspler AL, Bolshin C, Vernon SD, Broderick G. Evidence of inflammatory immune signaling in chronic fatigue syndrome: A pilot study of gene expression in peripheral blood. Behav Brain Funct. 2008 Sep 26;4:44. doi: 10.1186/1744-9081-4-44. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2569951/ (Full article)

 

Hypothalamic digoxin, cerebral chemical dominance and myalgic encephalomyelitis

Abstract:

The isoprenoid pathway was assessed in 15 patients with chronic fatigue syndrome. The pathway was also assessed in individuals with differing hemispheric dominance to assess whether hemispheric dominance had any correlation with these disease states.

The isoprenoid metabolites–digoxin, dolichol, and ubiquinone–RBC membrane Na+-K+ ATPase activity, serum magnesium and tyrosine/tryptophan catabolic patterns were assessed. The free-radical metabolism, glycoconjugate metabolism, and RBC membrane composition was also assessed. Membrane Na+-K+ ATPase activity and serum magnesium levels were decreased while HMG CoA reductase activity and serum digoxin levels were increased in myalgic encephalomyelitis (ME). There were increased levels of tryptophan catabolites–nicotine, strychnine, quinolinic acid, and serotonin–and decreased levels of tyrosine catabolites–dopamine, noradrenaline, and morphine in ME. There was an increase in dolichol levels, carbohydrate residues of glycoproteins, glycolipids, total/individual GAG fractions, and lysosomal enzymes in ME. Reduced levels of ubiquinone, reduced glutathione, and free-radical scavenging enzymes, as well as increased lipid peroxidation products and nitric oxide, were noticed in ME.

The biochemical patterns in ME correlated with those obtained in right hemispheric chemical dominance. The role of hypothalamic digoxin and neurotransmitter induced immune activation, altered glycoconjugate metabolism, and resultant defective viral antigen presentation, NMDA excitotoxicity and cognitive dysfunction, and mitochondrial dysfunction related myalgia in the pathogenesis of ME is stressed. ME occurs in individuals with right hemispheric chemical dominance.

 

Source: Kurup RK, Kurup PA. Hypothalamic digoxin, cerebral chemical dominance and myalgic encephalomyelitis. Int J Neurosci. 2003 May;113(5):683-701. https://ammes.orgwp-admin/post-new.php