Tag: innate immunity

Immune exhaustion in ME/CFS and long COVID

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID are debilitating multisystemic conditions sharing similarities in immune dysregulation and cellular signaling pathways contributing to the pathophysiology. In this study, immune exhaustion gene expression was investigated in participants with ME/CFS or long COVID concurrently.

RNA was extracted from peripheral blood mononuclear cells isolated from participants with ME/CFS (n = 14), participants with long COVID (n = 15), and healthy controls (n = 18). Participants with ME/CFS were included according to Canadian Consensus Criteria. Participants with long COVID were eligible according to the case definition for “Post COVID-19 Condition” published by the World Health Organization. RNA was analyzed using the NanoString nCounter Immune Exhaustion gene expression panel.

Differential gene expression analysis in ME/CFS revealed downregulated IFN signaling and immunoglobulin genes, and this suggested a state of immune suppression. Pathway analysis implicated dysregulated macrophage activation, cytokine production, and immunodeficiency signaling.

Long COVID samples exhibited dysregulated expression of genes regarding antigen presentation, cytokine signaling, and immune activation. Differentially expressed genes were associated with antigen presentation, B cell development, macrophage activation, and cytokine signaling.

This investigation elucidates the intricate role of both adaptive and innate immune dysregulation underlying ME/CFS and long COVID, emphasizing the potential importance of immune exhaustion in disease progression.

Source: Natalie Eaton-Fitch, Penny Rudd, Teagan Er, Livia Hool, Lara Herrero, and Sonya Marshall-Gradisnik. Immune exhaustion in ME/CFS and long COVID. JCI Insight. 2024;9(20):e183810. https://doi.org/10.1172/jci.insight.183810. https://insight.jci.org/articles/view/183810 (Full text)

Impact of age and sex on neuroinflammation following SARS-CoV-2 infection in a murine model

Abstract:

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, is known to infect people of all ages and both sexes. Senior populations have the greatest risk of severe COVID-19, and sexual dimorphism in clinical outcomes has been reported. Neurological symptoms are widely observed in COVID-19 patients, with many survivors exhibiting persistent neurological and cognitive impairment. The present study aims to investigate the impact of age and sex on the neuroinflammatory response to SARS-CoV-2 infection using a mouse model. Wild-type C57BL/6J mice were intranasally inoculated with SARS-CoV-2 lineage B.1.351, a variant known to infect mice.

Older male mice exhibited a significantly greater weight loss and higher viral loads in the lung at 3 days post infection. Notably, no viral RNA was detected in the brains of infected mice. Nevertheless, expression of IL-6, TNF-α, and CCL-2 in the lung and brain increased with viral infection. RNA-seq transcriptomic analysis of brains showed that SARS-CoV-2 infection caused significant changes in gene expression profiles, implicating innate immunity, defense response to virus, and cerebrovascular and neuronal functions.

These findings demonstrate that SARS-CoV-2 infection triggers a neuroinflammatory response, despite the lack of detectable virus in the brain. Aberrant activation of innate immune response, disruption of blood-brain barrier and endothelial cell integrity, and suppression of neuronal activity and axonogenesis underlie the impact of SARS-CoV-2 infection on the brain. Understanding the role of these affected pathways in SARS-CoV-2 pathogenesis helps identify appropriate points of therapeutic interventions to alleviate neurological dysfunction observed during COVID-19.

Source: Krishna VD, Chang A, Korthas H, Var SR, Low WC, Li L, Cheeran MC. Impact of age and sex on neuroinflammation following SARS-CoV-2 infection in a murine model. bioRxiv [Preprint]. 2023 Aug 14:2023.08.11.552998. doi: 10.1101/2023.08.11.552998. Update in: Front Microbiol. 2024 Jul 15;15:1404312. doi: 10.3389/fmicb.2024.1404312. PMID: 37645925; PMCID: PMC10462071. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10462071/ (Full text)

Chronic fatigue syndrome: number of patients is expected to double due to long-term effects of the COVID-19 pandemic

Press Release:

Up to 80,000 people in Austria are estimated to suffer from chronic fatigue syndrome, also known as ME/CFS or myalgic encephalomyelitis/chronic fatigue syndrome. The number of ME/CFS patients is expected to rise drastically due to long-term effects of the COVID-19 pandemic. However, research in the field has neither identified mechanisms of disease onset nor causal treatment approaches. Scientists at MedUni Vienna have now identified possible biomarkers that could improve the diagnosis and treatment of long-lasting and debilitating fatigue. The study has recently been published in the Journal of Clinical Medicine.

The study by Eva Untersmayr-Elsenhuber and her team from MedUni Vienna’s Center for Pathophysiology, Infectiology and Immunology builds on earlier research on immune disorders and the intestinal barrier function in patients with ME/CFS. It is well known that ME/CFS patients often differ greatly in the clinical manifestations of their disease. However, despite intensive research, there is still no measurable parameter (biomarker) that clearly indicates the disease.

As the MedUni Vienna research team shows, ME/CFS patients can be divided into subgroups based on the function of their immune system. The study was able to identify various biomarkers in the patients that indicate immune system disorders or reduced intestinal barrier function. As a result, differences relevant to clinical care were identified in ME/CFS patients that would have remained undetected without the previous immunological stratification of the ME/CFS patient group. “In our study, we see that the immunological evaluation of ME/CFS patients is of crucial importance. Patients suffering from immunodeficiencies are characterised by an altered innate immune function. In ME/CFS patients with an intact immune system, the intestinal barrier function was reduced,” explains the study’s principal investigator Eva Untersmayr-Elsenhuber. According to the researchers, this not only provides a more detailed insight in different disease mechanisms, but also indicates that depending on the patient’s immune competence, some treatment approaches might be more suitable than others.

The next step will be to review the study results on a larger scale. In order to advance research in the field, the first ME/CFS Biobank in Austria is currently being set up at MedUni Vienna with the support of the WE&ME Foundation. “ME/CFS Biobank Austria” collects human samples, which will be made available for future research projects. Untersmayr-Elsenhuber: “To ensure that ME/CFS research can take place quickly and transnationally in the future, we have been coordinating with research groups in the UK, the Netherlands and Germany from the outset.”

25 per cent of those affected are bedridden

ME/CFS is a severe multisystemic disease that often leads to a high degree of disability. 60 per cent of patients are unable to work full-time and 25 per cent are bedridden. The exact causes of the disease are still unclear. As diagnosis is difficult due to the lack of biomarkers, the number of people affected cannot be precisely quantified. According to current studies, between 26,000 and 80,000 people in Austria suffer from chronic fatigue. Due to Covid-19, this number could double in the next few years. The links between infection with SARS-CoV-2 and ME/CFS are also the subject of intensive research.

JOURNAL

Journal of Clinical Medicine

DOI

10.3390/jcm13010275 

ARTICLE TITLE

Immunological Patient Stratification in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

ARTICLE PUBLICATION DATE

3-Jan-2024

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)

Innate Immune Activation and Mitochondrial ROS Invoke Persistent Cardiac Conduction System Dysfunction after COVID-19

Abstract:

Background Cardiac risk rises during acute SARS-CoV-2 infection and in long COVID syndrome in humans, but the mechanisms behind COVID-19-linked arrhythmias are unknown. This study explores the acute and long term effects of SARS-CoV-2 on the cardiac conduction system (CCS) in a hamster model of COVID-19.

Methods Radiotelemetry in conscious animals was used to non-invasively record electrocardiograms and subpleural pressures after intranasal SARS-CoV-2 infection. Cardiac cytokines, interferon-stimulated gene expression, and macrophage infiltration of the CCS, were assessed at 4 days and 4 weeks post-infection. A double-stranded RNA mimetic, polyinosinic:polycytidylic acid (PIC), was used in vivo and in vitro to activate viral pattern recognition receptors in the absence of SARS-CoV-2 infection.

Results COVID-19 induced pronounced tachypnea and severe cardiac conduction system (CCS) dysfunction, spanning from bradycardia to persistent atrioventricular block, although no viral protein expression was detected in the heart. Arrhythmias developed rapidly, partially reversed, and then redeveloped after the pulmonary infection was resolved, indicating persistent CCS injury. Increased cardiac cytokines, interferon-stimulated gene expression, and macrophage remodeling in the CCS accompanied the electrophysiological abnormalities. Interestingly, the arrhythmia phenotype was reproduced by cardiac injection of PIC in the absence of virus, indicating that innate immune activation was sufficient to drive the response. PIC also strongly induced cytokine secretion and robust interferon signaling in hearts, human iPSC-derived cardiomyocytes (hiPSC-CMs), and engineered heart tissues, accompanied by alterations in electrical and Ca2+ handling properties. Importantly, the pulmonary and cardiac effects of COVID-19 were blunted by in vivo inhibition of JAK/STAT signaling or by a mitochondrially-targeted antioxidant.

Conclusions The findings indicate that long term dysfunction and immune cell remodeling of the CCS is induced by COVID-19, arising indirectly from oxidative stress and excessive activation of cardiac innate immune responses during infection, with implications for long COVID Syndrome.

Source: Deepthi Ashok, Ting Liu, Joseph Criscione, Meghana Prakash, Byunggik Kim, Julian Chow, Morgan Craney, Kyriakos N. Papanicolaou, Agnieszka Sidor, D. Brian Foster, Andrew Pekosz, Jason Villano, Deok-Ho Kim, Brian O’Rourke. Innate Immune Activation and Mitochondrial ROS Invoke Persistent Cardiac Conduction System Dysfunction after COVID-19. bioRxiv 2024.01.05.574280; doi: https://doi.org/10.1101/2024.01.05.574280 https://www.biorxiv.org/content/10.1101/2024.01.05.574280v1.full (Full text)

Long-COVID-19: the persisting imprint of SARS-CoV-2 infections on the innate immune system

In a recent Cell publication, Cheong et al. uncover how COVID-19 causes IL-6 induced epigenetic reprogramming of human immune stem cells, which causes lasting alterations in the composition and response characteristics of circulating immune cells.1 The study provides important insights into the mechanisms by which SARS-CoV-2 infections impact the human immune system and is an important hook into unraveling the mechanisms of post-acute sequelae of COVID-19 (PASC) commonly referred to as long-COVID.

While vaccination and drugs are reducing the societal impact of acute SARS-CoV-2 infections, between 10 and 40% of patients continue to suffer long after the acute infection has been cleared. The diverse PASC symptoms range from short breath and headaches to cognitive impairment (‘brain fog’) and debilitating fatigue. Not only are no treatments for PASC available but also the underlying molecular mechanisms remain opaque.2

Cheong et al. investigated in patients’ circulating immune cells if detectable changes persisted after clearance of the acute SARS-CoV-2 infection 3 weeks after the first symptoms. They assembled a cohort of COVID-19 convalescent patients, which was sampled between 1–3 and 4–12 months after SARS-CoV-2 infections requiring intensive care unit (ICU) admission and compared these patients to non-infected controls and to patients that had been on the ICU for different reasons. Focusing on peripheral blood mononuclear cells (PBMC) they investigated transcriptional or epigenetic changes using an integrated pipeline of single-nuclei transcriptome analysis and ATAC-seq sequencing, which identifies accessible chromatin regions. Among PBMCs CD14+ monocytes exhibited the most drastic changes. CD14+ monocytes are a group of heterogenous, short-lived antigen presenting cells that help orchestrating immune responses. Among these the authors could distinguish one cluster, M.SC3, which was more abundant even 12 months after the infection. Cells in this cluster resembled intermediate-type monocytes with functions that altogether resemble dendritic cells, the most effective amongst professional antigen presenting cells. In response to stimuli indicating viral infections, post-COVID monocytes showed up to 100-fold increased secretion of proinflammatory cytokines and enhanced transcriptional responses relating to cytokine signaling and monocyte activation. ATAC-seq also revealed a persistent pattern of differentially accessible chromatin which increased in abundance in early convalescent patients and did not return to the low levels observed in healthy individuals even 12 months after the acute infection. Thus, following severe SARS-CoV-2 infections, patients’ CD14+ monocytes carry specific and persistent epigenetic changes that puts them into an alerted state with heightened response characteristics.

Given that monocytes have a lifespan of a single day, the discovery of persistent epigenetic changes is notable and may reflect altered hematopoiesis and inheritance of epigenetic states from hematopoietic stem and progenitor cells (HSPC). To overcome the challenges associated with obtaining bone marrow resident HSPC, Cheong et al. developed a platform to enrich rare circulating HSPCs from PBMC and demonstrated that these faithfully represent the diversity and functional characteristics of their bone marrow-derived counterparts. With this platform, they discovered lasting epigenetic changes in HSPC of post-COVID patients that resembled those observed in mature monocytes. Especially late post-COVID HSPC exhibited skewed hematopoiesis with a significant increase of granulocyte monocyte precursor (GMP) cells. Intriguingly, the stem cells and the mature monocytes shared epigenetic signatures indicating that epigenetic and transcriptional programs are inherited by the mature progeny. The previously identified M.SC3 module activity was similarly increased in stem cells of the same patients.

Read the rest of this article HERE. 

Source: Boes, M., Falter-Braun, P. Long-COVID-19: the persisting imprint of SARS-CoV-2 infections on the innate immune system. Sig Transduct Target Ther 8, 460 (2023). https://doi.org/10.1038/s41392-023-01717-9 https://www.nature.com/articles/s41392-023-01717-9 (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)

Cytometry profiling of ex vivo recall responses to Coxiella burnetii in previously naturally exposed individuals reveals long-term changes in both adaptive and innate immune cellular compartments

Abstract:

Introduction: Q fever, caused by the intracellular bacterium Coxiella burnetii, is considered an occupational and biodefense hazard and can result in debilitating long-term complications. While natural infection and vaccination induce humoral and cellular immune responses, the exact nature of cellular immune responses to C. burnetii is incompletely understood. The current study seeks to investigate more deeply the nature of long-term cellular recall responses in naturally exposed individuals by both cytokine release assessment and cytometry profiling.

Methods: Individuals exposed during the 2007-2010 Dutch Q fever outbreak were grouped in 2015, based on a C. burnetii-specific IFNγ release assay (IGRA), serological status, and self-reported clinical symptoms during initial infection, into asymptomatic IGRA-negative/seronegative controls, and three IGRA-positive groups (seronegative/asymptomatic; seropositive/asymptomatic and seropositive/symptomatic). Recall responses following in vitro re-stimulation with heat-inactivated C. burnetii in whole blood, were assessed in 2016/2017 by cytokine release assays (n=55) and flow cytometry (n=36), and in blood mononuclear cells by mass cytometry (n=36).

Results: Cytokine release analysis showed significantly elevated IL-2 responses in all seropositive individuals and elevated IL-1β responses in those recovered from symptomatic infection. Comparative flow cytometry analysis revealed significantly increased IFNγ, TNFα and IL-2 recall responses by CD4 T cells and higher IL-6 production by monocytes from symptomatic, IGRA-positive/seropositive individuals compared to controls. Mass cytometry profiling and unsupervised clustering analysis confirmed recall responses in seropositive individuals by two activated CD4 T cell subsets, one characterized by a strong Th1 cytokine profile (IFNγ+IL-2+TNFα+), and identified C. burnetii-specific activation of CD8 T cells in all IGRA-positive groups. Remarkably, increased C. burnetii-specific responses in IGRA-positive individuals were also observed in three innate cell subpopulations: one characterized by an IFNγ+IL-2+TNFα+ Th1 cytokine profile and lack of canonical marker expression, and two IL-1β-, IL-6- and IL-8-producing CD14+ monocyte subsets that could be the drivers of elevated secretion of innate cytokines in pre-exposed individuals.

Discussion: These data highlight that there are long-term increased responses to C. burnetii in both adaptive and innate cellular compartments, the latter being indicative of trained immunity. These findings warrant future studies into the protective role of these innate responses and may inform future Q fever vaccine design.

Source: Raju Paul S, Scholzen A, Reeves PM, Shepard R, Hess JM, Dzeng RK, Korek S, Garritsen A, Poznansky MC, Sluder AE. Cytometry profiling of ex vivo recall responses to Coxiella burnetii in previously naturally exposed individuals reveals long-term changes in both adaptive and innate immune cellular compartments. Front Immunol. 2023 Oct 11;14:1249581. doi: 10.3389/fimmu.2023.1249581. PMID: 37885896; PMCID: PMC10598782. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10598782/ (Full text)

Persistent immune and clotting dysfunction detected in saliva and blood plasma after COVID-19

Abstract:

A growing number of studies indicate that coronavirus disease 2019 (COVID-19) is associated with inflammatory sequelae, but molecular signatures governing the normal versus pathologic convalescence process have not been well-delineated. Here, we characterized global immune and proteome responses in matched plasma and saliva samples obtained from COVID-19 patients collected between 20 and 90 days after initial clinical symptoms resolved.

Convalescent subjects showed robust total IgA and IgG responses and positive antibody correlations in saliva and plasma samples. Shotgun proteomics revealed persistent inflammatory patterns in convalescent samples including dysfunction of salivary innate immune cells, such as neutrophil markers (e.g., myeloperoxidase), and clotting factors in plasma (e.g., fibrinogen), with positive correlations to acute COVID-19 disease severity. Saliva samples were characterized by higher concentrations of IgA, and proteomics showed altered myeloid-derived pathways that correlated positively with SARS-CoV-2 IgA levels.

Beyond plasma, our study positions saliva as a viable fluid to monitor normal and aberrant immune responses including vascular, inflammatory, and coagulation-related sequelae.

Source: Jang H, Choudhury S, Yu Y, Sievers BL, Gelbart T, Singh H, Rawlings SA, Proal A, Tan GS, Qian Y, Smith D, Freire M. Persistent immune and clotting dysfunction detected in saliva and blood plasma after COVID-19. Heliyon. 2023 Jul 4;9(7):e17958. doi: 10.1016/j.heliyon.2023.e17958. PMID: 37483779; PMCID: PMC10362241. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10362241/ (Full text)

Characterisation of cell functions and receptors in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME)

Abstract:

BACKGROUND: Abnormal immune function is often an underlying component of illness pathophysiology and symptom presentation. Functional and phenotypic immune-related alterations may play a role in the obscure pathomechanism of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME). The objective of this study was to investigate the functional ability of innate and adaptive immune cells in moderate and severe CFS/ME patients. The 1994 Fukuda criteria for CFS/ME were used to define CFS/ME patients. CFS/ME participants were grouped based on illness severity with 15 moderately affected (moderate) and 12 severely affected (severe) CFS/ME patients who were age and sex matched with 18 healthy controls. Flow cytometric protocols were used for immunological analysis of dendritic cells, monocytes and neutrophil function as well as measures of lytic proteins and T, natural killer (NK) and B cell receptors.

RESULTS: CFS/ME patients exhibited alterations in NK receptors and adhesion markers and receptors on CD4(+)T and CD8(+)T cells. Moderate CFS/ME patients had increased CD8(+) CD45RA effector memory T cells, SLAM expression on NK cells, KIR2DL5(+) on CD4(+)T cells and BTLA4(+) on CD4(+)T central memory cells. Moderate CFS/ME patients also had reduced CD8(+)T central memory LFA-1, total CD8(+)T KLRG1, naïve CD4(+)T KLRG1 and CD56(dim)CD16(-) NK cell CD2(+) and CD18(+)CD2(+). Severe CFS/ME patients had increased CD18(+)CD11c(-) in the CD56(dim)CD16(-) NK cell phenotype and reduced NKp46 in CD56(bright)CD16(dim) NK cells.

CONCLUSIONS: This research accentuated the presence of immunological abnormalities in CFS/ME and highlighted the importance of assessing functional parameters of both innate and adaptive immune systems in the illness.

 

Source: Hardcastle SL, Brenu EW, Johnston S, Nguyen T, Huth T, Wong N, Ramos S, Staines D, Marshall-Gradisnik S. Characterisation of cell functions and receptors in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME). BMC Immunol. 2015 Jun 2;16:35. doi: 10.1186/s12865-015-0101-4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4450981/ (Full article)