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)

An exploration of the experiences and self-generated strategies used when navigating everyday life with Long Covid

Abstract:

Background: Around one in ten people who contract Covid-19 report ongoing symptoms or ‘Long Covid’. Without any known interventions to cure the condition, forms of self-management are routinely prescribed by healthcare professionals and described by people with the condition. However, there is limited research exploring what strategies are used to navigate everyday life with Long Covid, and experiences that initiate development of these strategies. Our study aimed to explore the range and influence of self-generated strategies used by people with Long Covid to navigate everyday life within the context of their own condition.

Methods: Forming part of the Long Covid Personalised Self-managemenT support co-design and EvaluatioN (LISTEN) project, we conducted a qualitative study using narrative interviews with adults who were not hospitalised with Covid-19. Participants aged over 18 years, who self-identified with Long Covid, were recruited from England and Wales. Data were analysed with patient contributors using a reflexive thematic analysis.

Results: Eighteen participants (mean age = 44 years, SD = 13 years) took part in interviews held between December 2021 and February 2022. Themes were constructed which depicted 1) the landscape behind the Long Covid experience and 2) the everyday experience of participants’ Long Covid. The everyday experience comprised a combination of physical, emotional, and social factors, forming three sub-themes: centrality of physical symptoms, navigating ‘experts’ and the ‘true colour’ of personal communities, and a rollercoaster of psychological ambiguity). The third theme, personal strategies to manage everyday life was constructed from participants’ unique presentations and self-generated solutions to manage everyday life. This comprised five sub-themes: seeking reassurance and knowledge, developing greater self-awareness through monitoring, trial and error of ‘safe’ ideas, building in pleasure and comfort, and prioritising ‘me’.

Conclusions: Among this sample of adults with Long Covid, their experiences highlighted the unpredictable nature of the condition but also the use of creative and wide ranging self-generated strategies. The results offer people with Long Covid, and healthcare professionals supporting them, an overview of the collective evidence relating to individuals’ self-management which can enable ways to live ‘better’ and regain some sense of identity whilst facing the impact of a debilitating, episodic condition.

Trial registration: LISTEN ISRCTN36407216.

Source: Leggat FJ, Heaton-Shrestha C, Fish J, Siriwardena AN, Domeney A, Rowe C, Patel I, Parsons J, Blair J, Jones F. An exploration of the experiences and self-generated strategies used when navigating everyday life with Long Covid. BMC Public Health. 2024 Mar 13;24(1):789. doi: 10.1186/s12889-024-18267-6. PMID: 38481230; PMCID: PMC10938753. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10938753/ (Full text)

Comparison of the muscle oxygenation during submaximal and maximal exercise tests in patients post-coronavirus disease 2019 syndrome with pulmonary involvement

Abstract:

Introduction: Pulmonary involvement is prevalent in patients with coronavirus disease 2019 (COVID-19). Arterial hypoxemia may reduce oxygen transferred to the skeletal muscles, possibly leading to impaired exercise capacity. Oxygen uptake may vary depending on the increased oxygen demand of the muscles during submaximal and maximal exercise.

Objective: This study aimed to compare muscle oxygenation during submaximal and maximal exercise tests in patients with post-COVID-19 syndrome with pulmonary involvement.

Methods: Thirty-nine patients were included. Pulmonary function (spirometry), peripheral muscle strength (dynamometer), quadriceps femoris (QF) muscle oxygenation (Moxy® device), and submaximal exercise capacity (six-minute walk test (6-MWT)) were tested on the first day, maximal exercise capacity (cardiopulmonary exercise test (CPET)) was tested on the second day. Physical activity level was evaluated using an activity monitor worn for five consecutive days. Cardiopulmonary responses and muscle oxygenation were compared during 6-MWT and CPET.

Results: Patients’ minimum and recovery muscle oxygen saturation were significantly decreased; maximum total hemoglobin increased, heart rate, blood pressure, breathing frequency, dyspnea, fatigue, and leg fatigue at the end-of-test and recovery increased in CPET compared to 6-MWT (p < .050). Peak oxygen consumption (VO2peak) was 18.15 ± 4.75 ml/min/kg, VO2peak; percent predicted < 80% was measured in 51.28% patients. Six-MWT distance and QF muscle strength were less than 80% predicted in 58.9% and 76.9% patients, respectively.

Conclusions: In patients with post-COVID-19 syndrome with pulmonary involvement, muscle deoxygenation of QF is greater during maximal exercise than during submaximal exercise. Specifically, patients with lung impairment should be evaluated for deoxygenation and should be taken into consideration during pulmonary rehabilitation.

Source: Kavalcı Kol B, Boşnak Güçlü M, Baytok E, Yılmaz Demirci N. Comparison of the muscle oxygenation during submaximal and maximal exercise tests in patients post-coronavirus disease 2019 syndrome with pulmonary involvement. Physiother Theory Pract. 2024 Mar 12:1-14. doi: 10.1080/09593985.2024.2327534. Epub ahead of print. PMID: 38469863. https://pubmed.ncbi.nlm.nih.gov/38469863/

Health outcomes for Long COVID are comparable with ME/CFS

Press Release: Griffith News

People with Long COVID in Australia have poor health outcomes that are comparable with another emerging disease known as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), new Griffith University research has discovered.

PhD student Breanna Weigel from Griffith’s National Centre for Neuroimmunology and Emerging Diseases (NCNED) will be presenting the findings in Singapore this month at the International Public Health Conference.

Ms Weigel said the study found people with Long COVID have the same health outcomes as ME/CFS over a 12-month period.

“Quality of life and disability scores were significantly poorer for both Long COVID and ME/CFS when compared with healthy people,” she said.

“However, there were no differences between ME/CFS and Long COVID groups which indicates considerable reductions in functional capacity and health and well-being among people living with these illnesses.”

The research found only a few differences in more than 25 different symptoms between Long COVID and ME/CFS participants.

Importantly, both ME/CFS and Long COVID groups had comparable prevalence with the severity of their illness.

Both groups over time had the same symptom presentation of significantly impaired cognition, mobility, bodily pain, and post-exertional malaise (PEM) which means symptoms get worse after physical or mental activity.

PEM is very disabling and causes changes in symptoms and a further reduction in ability to do everyday activities.

Director of the NCNED, Professor Sonya Marshall-Gradisnik, said: “This research highlighted the continued impact of Long COVID on peoples’ lives, which is especially poignant as today we recognise International Long COVID Awareness Day.”

“The research forms one of many Long COVID investigations and clinical trials being undertaken at the national centre where it is hoped these findings will provide pathways for those with Long COVID.

“We are uniquely positioned nationally as we are the only centre to undertake scientific laboratory and MRI research in Long COVID and ME/CFS in tandem, and monitor the health and economic impact of the patients.

“At the national centre we also undertake clinical trials and contribute to best practice guidelines such as the recently published guidelines in the British Medical Journal for ME.”

Dr Natalie Eaton-Fitch, who was an undergraduate student at Griffith University and is now an emerging researcher at the NCNED said: “Researchers are very fortunate to have wonderful opportunities at all stages of their careers and to know research can make a real-world difference for people.”

Ms Weigel’s work builds upon the Issues Brief she did in collaboration with the Deeble Institute that reported how patient experiences can guide the development of Long COVID health policy.

 

Impaired Sleep in Patients with Post-COVID-19 Syndrome Compared to Healthy Controls: A Cross-Sectional Trial

Abstract:

Introduction: To objectify self-reported sleep disorders in individuals with post-COVID-syndrome (PCS), we aimed to investigate the prevalence and nature of sleep disturbances by polysomnography (PSG) in PCS compared to healthy individuals.

Methods: People with PCS (n = 21) and healthy controls (CON, n = 10) were included in this prospective trial. At baseline, clinical and social anamnesis, lung function, 1 min sit-to-stand test (STST) and Pittsburgh Sleep Quality Index (PSQI) were assessed. For a single-night, sleep health was evaluated by video-PSG. The apnoea/hypopnea index (AHI) was used as the primary outcome.

Results: Twenty patients with PCS (50 ± 11 y, BMI 27.1 m2/kg, SARS-CoV-2 infection 8.5 ± 4.5 months ago) and 10 CON participants (46 ± 10 y, BMI 23.0 m2/kg, no SARS-CoV-2 infection in the history) completed the study. Forced vital capacity (p = 0.018), STST repetitions (p &lt; 0.001), and symptoms of dyspnoea (at rest: p = 0.002, exertion: p &lt; 0.001) were worse in PCS compared to CON. PSQI score (PCS: 7.5 ± 4.7 points) was higher in PCS compared to CON (Δ = 3.7 points, 95% CI [0.4-7.1] p = 0.015), indicating poor sleep in 80% of patients with PCS. Although PSG showed comparable sleep stage distributions in both groups, AHI (Δ = 9.0 n/h, 95% CI [3.3-14.8], p = 0.002), PLM index (Δ = 5.1 n/h, 95% CI [0.4-9.8], p = 0.017), and the prevalence of sleep apnoea (60% vs. 10%, p = 0.028) was significantly higher in PCS compared to CON.

Conclusion: Quantifiable subjective limitations of sleep have been revealed by PSG data in this PCS cohort. More than half of PCS patients had signs of sleep apnoea, highlighting the importance of sleep screening in PCS.

Source: Jarosch I, Schneeberger T, Stegemann A, Gloeckl R, Leitl D, Dennis C, Hitzl W, Schoen C, Koczulla AR. Impaired Sleep in Patients with Post-COVID-19 Syndrome Compared to Healthy Controls: A Cross-Sectional Trial. Respiration. 2024 Mar 1:1-5. doi: 10.1159/000536272. Epub ahead of print. PMID: 38432219. https://karger.com/res/article/doi/10.1159/000536272/896169/Impaired-Sleep-in-Patients-with-Post-COVID-19 (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)

Blood–brain barrier disruption and sustained systemic inflammation in individuals with long COVID-associated cognitive impairment

Abstract:

Vascular disruption has been implicated in coronavirus disease 2019 (COVID-19) pathogenesis and may predispose to the neurological sequelae associated with long COVID, yet it is unclear how blood–brain barrier (BBB) function is affected in these conditions. Here we show that BBB disruption is evident during acute infection and in patients with long COVID with cognitive impairment, commonly referred to as brain fog.

Using dynamic contrast-enhanced magnetic resonance imaging, we show BBB disruption in patients with long COVID-associated brain fog. Transcriptomic analysis of peripheral blood mononuclear cells revealed dysregulation of the coagulation system and a dampened adaptive immune response in individuals with brain fog.

Accordingly, peripheral blood mononuclear cells showed increased adhesion to human brain endothelial cells in vitro, while exposure of brain endothelial cells to serum from patients with long COVID induced expression of inflammatory markers.

Together, our data suggest that sustained systemic inflammation and persistent localized BBB dysfunction is a key feature of long COVID-associated brain fog.

Source: Greene C, Connolly R, Brennan D, Laffan A, O’Keeffe E, Zaporojan L, O’Callaghan J, Thomson B, Connolly E, Argue R, Martin-Loeches I, Long A, Cheallaigh CN, Conlon N, Doherty CP, Campbell M. Blood-brain barrier disruption and sustained systemic inflammation in individuals with long COVID-associated cognitive impairment. Nat Neurosci. 2024 Mar;27(3):421-432. doi: 10.1038/s41593-024-01576-9. Epub 2024 Feb 22. PMID: 38388736; PMCID: PMC10917679. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10917679/ (Full text)

What is the impact of long-term COVID-19 on workers in healthcare settings? A rapid systematic review of current evidence

Abstract:

Background: Long COVID is a devastating, long-term, debilitating illness which disproportionately affects healthcare workers, due to the nature of their work. There is currently limited evidence specific to healthcare workers about the experience of living with Long COVID, or its prevalence, pattern of recovery or impact on healthcare.

Objective: Our objective was to assess the effects of Long COVID among healthcare workers and its impact on health status, working lives, personal circumstances, and use of health service resources.

Methods: We conducted a systematic rapid review according to current methodological standards and reported it in adherence to the PRISMA 2020 and ENTREQ statements.

Results: We searched relevant electronic databases and identified 3770 articles of which two studies providing qualitative evidence and 28 survey studies providing quantitative evidence were eligible. Thematic analysis of the two qualitative studies identified five themes: uncertainty about symptoms, difficulty accessing services, importance of being listened to and supported, patient versus professional identity and suggestions to improve communication and services for people with Long COVID. Common long-term symptoms in the survey studies included fatigue, headache, loss of taste and/or smell, breathlessness, dyspnoea, difficulty concentrating, depression and anxiety.

Conclusion: Healthcare workers struggled with their dual identity (patient/doctor) and felt dismissed or not taken seriously by their doctors. Our findings are in line with those in the literature showing that there are barriers to healthcare professionals accessing healthcare and highlighting the challenges of receiving care due to their professional role. A more representative approach in Long COVID research is needed to reflect the diverse nature of healthcare staff and their occupations. This rapid review was conducted using robust methods with the codicil that the pace of research into Long COVID may mean relevant evidence was not identified.

Source: Cruickshank M, Brazzelli M, Manson P, Torrance N, Grant A. What is the impact of long-term COVID-19 on workers in healthcare settings? A rapid systematic review of current evidence. PLoS One. 2024 Mar 5;19(3):e0299743. doi: 10.1371/journal.pone.0299743. PMID: 38442116; PMCID: PMC10914278. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10914278/ (Full text)

Possible Role of Fibrinaloid Microclots in Postural Orthostatic Tachycardia Syndrome (POTS): Focus on Long COVID

Abstract:

Postural orthostatic tachycardia syndrome (POTS) is a common accompaniment of a variety of chronic, inflammatory diseases, including long COVID, as are small, insoluble, ‘fibrinaloid’ microclots.
We here develop the argument, with accompanying evidence, that fibrinaloid microclots, through their ability to block the flow of blood through microcapillaries and thus cause tissue hypoxia, are not simply correlated with but in fact, by preceding it, may be a chief intermediary cause of POTS, in which tachycardia is simply the body’s exaggerated ‘physiological’ response to hypoxia. Similar reasoning accounts for the symptoms bundled under the term ‘fatigue’.
Amyloids are known to be membrane disruptors, and when their targets are nerve membranes, this can explain neurotoxicity and hence the autonomic nervous system dysfunction that contributes to POTS. Taken together as a system view, we indicate that fibrinaloid microclots can serve to link POTS and fatigue in long COVID in a manner that is at once both mechanistic and explanatory. This has clear implications for the treatment of such diseases.
Source: Kell DB, Khan MA, Kane B, Lip GYH, Pretorius E. Possible Role of Fibrinaloid Microclots in Postural Orthostatic Tachycardia Syndrome (POTS): Focus on Long COVID. Journal of Personalized Medicine. 2024; 14(2):170. https://doi.org/10.3390/jpm14020170 https://www.mdpi.com/2075-4426/14/2/170 (Full text)

Unravelling shared mechanisms: insights from recent ME/CFS research to illuminate long COVID pathologies

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic illness often triggered by an initiating acute event, mainly viral infections. The transition from acute to chronic disease remains unknown, but interest in this phenomenon has escalated since the COVID-19 pandemic and the post-COVID-19 illness, termed ‘long COVID’ (LC). Both ME/CFS and LC share many clinical similarities.

Here, we present recent findings in ME/CFS research focussing on proposed disease pathologies shared with LC. Understanding these disease pathologies and how they influence each other is key to developing effective therapeutics and diagnostic tests. Given that ME/CFS typically has a longer disease duration compared with LC, with symptoms and pathologies evolving over time, ME/CFS may provide insights into the future progression of LC.

Source: Annesley SJ, Missailidis D, Heng B, Josev EK, Armstrong CW. Unravelling shared mechanisms: insights from recent ME/CFS research to illuminate long COVID pathologies. Trends Mol Med. 2024 Mar 4:S1471-4914(24)00028-5. doi: 10.1016/j.molmed.2024.02.003. Epub ahead of print. PMID: 38443223. https://www.sciencedirect.com/science/article/pii/S1471491424000285 (Full text)