Tag: long covid immunology

Inflammatory and vascular biomarkers in post-COVID-19 syndrome: A systematic review and meta-analysis of over 20 biomarkers

Abstract:

Severe acute respiratory syndrome coronavirus 2 may inflict a post-viral condition known as post-COVID-19 syndrome (PCS) or long-COVID. Studies measuring levels of inflammatory and vascular biomarkers in blood, serum, or plasma of COVID-19 survivors with PCS versus non-PCS controls have produced mixed findings. Our review sought to meta-analyse those studies. A systematic literature search was performed across five databases until 25 June 2022, with an updated search on 1 November 2022.

Data analyses were performed with Review Manager and R Studio statistical software. Twenty-four biomarkers from 23 studies were meta-analysed. Higher levels of C-reactive protein (Standardized mean difference (SMD) = 0.20; 95% CI: 0.02-0.39), D-dimer (SMD = 0.27; 95% CI: 0.09-0.46), lactate dehydrogenase (SMD = 0.30; 95% CI: 0.05-0.54), and leukocytes (SMD = 0.34; 95% CI: 0.02-0.66) were found in COVID-19 survivors with PCS than in those without PCS. After sensitivity analyses, lymphocytes (SMD = 0.30; 95% CI: 0.12-0.48) and interleukin-6 (SMD = 0.30; 95% CI: 0.12-0.49) were also significantly higher in PCS than non-PCS cases. No significant differences were noted in the remaining biomarkers investigated (e.g., ferritin, platelets, troponin, and fibrinogen). Subgroup analyses suggested the biomarker changes were mainly driven by PCS cases diagnosed via manifestation of organ abnormalities rather than symptomatic persistence, as well as PCS cases with duration of <6 than ≥6 months.

In conclusion, our review pinpointed certain inflammatory and vascular biomarkers associated with PCS, which may shed light on potential new approaches to understanding, diagnosing, and treating PCS.

Source: Yong SJ, Halim A, Halim M, Liu S, Aljeldah M, Al Shammari BR, Alwarthan S, Alhajri M, Alawfi A, Alshengeti A, Khamis F, Alsalman J, Alshukairi AN, Abukhamis NA, Almaghrabi FS, Almuthree SA, Alsulaiman AM, Alshehail BM, Alfaraj AH, Alhawaj SA, Mohapatra RK, Rabaan AA. Inflammatory and vascular biomarkers in post-COVID-19 syndrome: A systematic review and meta-analysis of over 20 biomarkers. Rev Med Virol. 2023 Jan 27:e2424. doi: 10.1002/rmv.2424. Epub ahead of print. PMID: 36708022. https://pubmed.ncbi.nlm.nih.gov/36708022/ 

Long-COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): Potential neurophysiological biomarkers for these enigmatic entities

Since early in the pandemic, fatigue has been recognized as one of the most common persistent complaints in individuals infected with SARS-CoV-2, and constitutes one main symptom of the so-called long-COVID syndrome. The term fatigue refers to a sustained feeling of tiredness, which can be present at rest; it is not directly related to physical activity, but can be exacerbated disproportionally by exertion.

Survivors of other recent coronavirus outbreaks, such as severe acute respiratory syndrome (SARS) in 2002 and Middle East respiratory syndrome (MERS) in 2012 also developed chronic fatigue. These ‘post-infectious’ fatigue syndromes, including long-COVID, resemble myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a chronic disorder of unknown physiopathology characterized by fatigue, post-exertional malaise, chronic muscle or skeletal pain, and cognitive impairment (‘brain fog’).

Despite it being an extremely disabling symptom, the results of routine examinations are often normal in patients complaining of lingering fatigue, a phenomenon that has also led the medical-scientific community to view this condition with skepticism.

In physiology, fatigue is defined as a decrease in the maximal force-generating capacity of a muscle during exercise. It may result from peripheral processes distal to the neuromuscular junction and from central processes controlling the discharge rate of motoneurons.

Physical fatigue related to both central and peripheral nervous system dysfunction can be assessed with neurophysiological techniques including transcranial magnetic stimulation (TMS) of the motor cortex, electrical stimulation of nerve trunks or intramuscular nerve fibers, and electromyography (EMG) recordings.

In August 2021, the first study showing myopathic changes in quantitative EMG (qEMG) in long-COVID patients with musculoskeletal symptoms was published (). The same authors demonstrated myopathic qEMG features and histopathological changes in skeletal muscle biopsies in 16 patients with complaints of fatigue, myalgia, and/or weakness persisting for up to 14 months after mild to moderate COVID-19 (). The wide variety of histological changes in this study, including muscle fiber atrophy, mitochondrial changes, subsarcolemmal accumulation, inflammation, capillaries alteration, suggests that skeletal muscle may be a major target of SARS-CoV-2.

On the opposite side of the neuroaxis, dysfunction in the activity of the primary motor cortex and reduced corticomotor output may underlie fatigue.

The first TMS study on motor cortex physiology was conducted on 12 patients with long-term fatigue and ‘brain fog’ after severe COVID-19 (). It showed disruption of the physiological mechanism of post-contraction depression, i.e., the transient decrease in the amplitude of motor evoked potentials and prolongation of the cortical silent period after a fatiguing motor task, which depends on cortical inhibitory mechanisms and has the protective purpose of preventing muscle overload. Impairment of intracortical GABAergic activity, as indicated by disrupted long-interval intracortical inhibition, together with reduced excitability of the primary motor cortex was subsequently demonstrated in 67 patients with fatigue and cognitive difficulties after mild COVID-19 (). These patients also presented selective deficits in executive functions. Based on these findings, the authors proposed that fatigue depends on altered excitability and neurotransmission within the motor cortex at rest, and on abnormal reactivity to muscular exercise. In addition, reduced executive control may contribute to exacerbating poor physical performance and fatigue tolerance ().

These objective neurophysiological and histopathological findings showed for the first time that fatigue may due both to pathological processes in the muscle (the effector of the motor command) and/or at the site of motor command processing. The mechanisms of chronic dysfunction of neural and muscle cells may be sustained by inflammation or dysimmunity, triggered by SARS-COV-2 in predisposed individuals.

Immune-inflammatory and neuroendocrine mechanisms have also been implicated in ME/CFS. In particular, increased production of autoantibodies against CNS and autonomic nervous system targets, such as the ß2 adrenergic receptor (ß2AdR), have been documented (). As ß2AdR are important vasodilators, their functional disturbance may result in vasoconstriction and hypoxemia with chronic muscular and cerebral hypoperfusion.

The COVID-19 pandemic is likely to greatly increase the incidence of ME/CFS, so that the intense research on the pathophysiological mechanisms of fatigue in long-COVID can help to shed light on a poorly understood and underestimated syndrome.

Source: Versace V, Tankisi H. Long-COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): Potential neurophysiological biomarkers for these enigmatic entities. Clin Neurophysiol. 2023 Jan 13;147:58-59. doi: 10.1016/j.clinph.2023.01.001. Epub ahead of print. PMID: 36657309; PMCID: PMC9838078. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9838078/ (Full text)

Can Baseline IL-6 Levels Predict Long COVID in Subjects Hospitalized for SARS-CoV-2 Disease?

Abstract:

The immune response to infection plays a crucial role in the pathogenesis of COVID-19, but several patients develop a wide range of persistent symptoms, which is becoming a major global health and economic burden. However, reliable indicators are not yet available to predict the persistence of symptoms typical of the so-called long COVID. Our study aims to explore an eventual role of IL-6 levels as a marker of long COVID. Altogether, 184 patients admitted to the COVID Medicine Unit of the University Hospital in Palermo, Italy, from the 1st of September 2020, were analyzed.

Patients were divided into two groups according to the IL-6 serum levels (normal or elevated), considering the serum IL-6 levels measured during the first four days of hospitalization. In our study, higher serum IL-6 levels were associated with a doubled higher risk of long COVID (OR = 2.05; 95% CI: 1.04-4.50) and, in particular, they were associated with a higher incidence of mobility decline (OR = 2.55; 95% CI: 1.08-9.40) and PTSD (OR = 2.38; 95% CI: 1.06-8.61). The analysis of our case series confirmed the prominent role of IL-6 levels in response to SARS-CoV-2 infection, as predictors not only of COVID-19 disease severity and unfavorable outcomes, but also long COVID development trends.

Source: Giannitrapani L, Mirarchi L, Amodeo S, Licata A, Soresi M, Cavaleri F, Casalicchio S, Ciulla G, Ciuppa ME, Cervello M, Barbagallo M, Veronese N, The Comepa Group. Can Baseline IL-6 Levels Predict Long COVID in Subjects Hospitalized for SARS-CoV-2 Disease? Int J Mol Sci. 2023 Jan 15;24(2):1731. doi: 10.3390/ijms24021731. PMID: 36675242. https://www.mdpi.com/1422-0067/24/2/1731 (Full text)

Long COVID: Is There a Role for Antidepressants?

Abstract:

Two years into this historic pandemic, the scientific and healthcare communities continue to learn a great deal regarding COVID-19. The most urgent and immediate focus has been on vaccine development for disease prevention/mitigation and on identification of effective therapeutic interventions for acute phase of illness. However, attention is increasingly being placed on formulating treatment strategies for individuals who are post-COVID-19 and experiencing a syndrome of persistent symptoms that is being referred to as long COVID.

One strategy is to repurpose drugs which have been approved for other conditions and subsequently assess their safety and efficacy when applied to COVID-19. In this light, antidepressant medications have garnered attention amidst evidence supporting anti-inflammatory and anti-viral properties.

In this article, we present purported anti-inflammatory mechanisms of antidepressants, review studies appearing in the literature to date regarding antidepressants and acute COVID-19, and discuss the utility of antidepressants as a potential therapeutic resource for long COVID.

Source: Rivas-Vázquez R, Carrazana EJ, Blais MA, Rey GJ, RivasVázquez E, Quintana AA. Long COVID: Is There a Role for Antidepressants? Neurol Curr Res. 2022;2(3):1019. https://www.medtextpublications.com/open-access/long-covid-is-there-a-role-for-antidepressants-1249.pdf (Full text)

Novel clinical and immunological features associated with persistent post-acute sequelae of COVID-19 after six months of follow-up: a pilot study

Abstract:

Background: Currently, there is scant information regarding the features associated to the persistence of post-COVID-19 syndrome, which is the main aim of the present study.

Methods: A cohort study of 102 COVID-19 patients was conducted. The post-COVID-19 symptoms were assessed by a standardised questionnaire. Lymphocyte immunophenotyping was performed by flow cytometry and chemokines/cytokines, neutrophil extracellular traps, the tripartite motif 63, anti-cellular, and anti-SARS-CoV-2 IgG antibodies were addressed in serum. The primary outcome was the persistence of post-COVID-19 syndrome after six months follow-up.

Results: Thirteen patients (12.7%) developed the primary outcome and had a more frequent history of post-COVID-19 syndrome 3 months after infection onset (p = .044), increased levels of IL-1α (p = .011) and IP-10 (p = .037) and increased CD57 expression in CD8+ T cells (p = .003). There was a trend towards higher levels of IFN-γ (p = .051), IL-1β (p = .062) and IL-6 (p = .087). The history of post COVID-19 in the previous 3 months, obesity, baseline serum MIP-1α and IP-10, and CD57 expression in CD8+ T cells were independently associated with the persistence of post-COVID-19 syndrome.

Conclusion: Our data suggest an important relationship between a pro-inflammatory state mediated through metabolic pathways related to obesity and increased cellular senescence as a key element in the persistence of post-COVID-19 syndrome at six months of follow-up.

Source: Torres-Ruiz J, Lomelín-Gascón J, Lira Luna J, Vargas-Castro AS, Pérez-Fragoso A, Nuñez-Aguirre M, Alcalá-Carmona B, Absalón-Aguilar A, Balderas-Miranda JT, Maravillas-Montero JL, Mejía-Domínguez NR, Núñez-Álvarez C, Llorente L, Romero-Ramírez S, Sosa-Hernández VA, Cervantes-Díaz R, Juárez-Vega G, Meza-Sánchez D, Rull-Gabayet M, Martínez-Juárez LA, Morales L, López-López LN, Negrete-Trujillo JA, Falcón-Lezama JA, Valdez-Vázquez RR, Gallardo-Rincón H, Tapia-Conyer R, Gómez-Martín D. Novel clinical and immunological features associated with persistent post-acute sequelae of COVID-19 after six months of follow-up: a pilot study. Infect Dis (Lond). 2023 Jan 13:1-12. doi: 10.1080/23744235.2022.2158217. Epub ahead of print. PMID: 36637466. https://www.tandfonline.com/doi/full/10.1080/23744235.2022.2158217 (Full text)

SARS-CoV-2 escape from cytotoxic T cells during long-term COVID-19

Abstract:

Evolution of SARS-CoV-2 in immunocompromised hosts may result in novel variants with changed properties. While escape from humoral immunity certainly contributes to intra-host evolution, escape from cellular immunity is poorly understood. Here, we report a case of long-term COVID-19 in an immunocompromised patient with non-Hodgkin’s lymphoma who received treatment with rituximab and lacked neutralizing antibodies.

Over the 318 days of the disease, the SARS-CoV-2 genome gained a total of 40 changes, 34 of which were present by the end of the study period. Among the acquired mutations, 12 reduced or prevented the binding of known immunogenic SARS-CoV-2 HLA class I antigens. By experimentally assessing the effect of a subset of the escape mutations, we show that they resulted in a loss of as much as ~1% of effector CD8 T cell response. Our results indicate that CD8 T cell escape represents a major underappreciated contributor to SARS-CoV-2 evolution in humans.

Source: Stanevich OV, Alekseeva EI, Sergeeva M, Fadeev AV, Komissarova KS, Ivanova AA, Simakova TS, Vasilyev KA, Shurygina AP, Stukova MA, Safina KR, Nabieva ER, Garushyants SK, Klink GV, Bakin EA, Zabutova JV, Kholodnaia AN, Lukina OV, Skorokhod IA, Ryabchikova VV, Medvedeva NV, Lioznov DA, Danilenko DM, Chudakov DM, Komissarov AB, Bazykin GA. SARS-CoV-2 escape from cytotoxic T cells during long-term COVID-19. Nat Commun. 2023 Jan 10;14(1):149. doi: 10.1038/s41467-022-34033-x. PMID: 36627290; PMCID: PMC9831376. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9831376/ (Full text)

The relationship between chronic immune response and neurodegenerative damage in long COVID-19

Abstract:

In the past two years, the world has faced the pandemic caused by the severe acute respiratory syndrome 2 coronavirus (SARS-CoV-2), which by August of 2022 has infected around 619 million people and caused the death of 6.55 million individuals globally. Although SARS-CoV-2 mainly affects the respiratory tract level, there are several reports, indicating that other organs such as the heart, kidney, pancreas, and brain can also be damaged.

A characteristic observed in blood serum samples of patients suffering COVID-19 disease in moderate and severe stages, is a significant increase in proinflammatory cytokines such as interferon-α (IFN-α), interleukin-1β (IL-1β), interleukin-2 (IL-2), interleukin-6 (IL-6) and interleukin-18 (IL-18), as well as the presence of autoantibodies against interferon-α (IFN-α), interferon-λ (IFN-λ), C-C motif chemokine ligand 26 (CCL26), CXC motif chemokine ligand 12 (CXCL12), family with sequence similarity 19 (chemokine (C-C motif)-like) member A4 (FAM19A4), and C-C motif chemokine ligand 1 (CCL1). Interestingly, it has been described that the chronic cytokinemia is related to alterations of blood-brain barrier (BBB) permeability and induction of neurotoxicity.

Furthermore, the generation of autoantibodies affects processes such as neurogenesis, neuronal repair, chemotaxis and the optimal microglia function. These observations support the notion that COVID-19 patients who survived the disease present neurological sequelae and neuropsychiatric disorders. The goal of this review is to explore the relationship between inflammatory and humoral immune markers and the major neurological damage manifested in post-COVID-19 patients.

Source: Elizalde-Díaz JP, Miranda-Narváez CL, Martínez-Lazcano JC, Martínez-Martínez E. The relationship between chronic immune response and neurodegenerative damage in long COVID-19. Front Immunol. 2022 Dec 16;13:1039427. doi: 10.3389/fimmu.2022.1039427. PMID: 36591299; PMCID: PMC9800881. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9800881/ (Full text)

Autoimmune complications of COVID-19 and potential consequences for long-lasting disease syndromes

Abstract:

The latest WHO report determined the increasing diversity within the CoV-2 omicron and its descendent lineages. Some heavily mutated offshoots of BA.5 and BA.2, such as BA.4.6, BF.7, BQ.1.1, and BA.2.75, are responsible for about 20% of infections and are spreading rapidly in multiple countries. It is a sign that Omicron subvariants are now developing a capacity to be more immune escaping and may contribute to a new wave of COVID-19.

Covid-19 infections often induce many alterations in human physiological defense and the natural control systems, with exacerbated activation of the inflammatory and homeostatic response, as for any infectious diseases. Severe activation of the early phase of hemostatic components, often occurs, leading to thrombotic complications and often contributing to a lethal outcome selectively in certain populations. Development of autoimmune complications increases the disease burden and lowers its prognosis.

While the true mechanism still remains unclear, it is believed to mainly be related to the host autoimmune responses as demonstrated, only in some patients suffering from the presence of autoantibodies that worsens the disease evolution. In fact in some studies the development of autoantibodies to angiotensin converting enzyme 2 (ACE2) was identified, and in other studies autoantibodies, thought to be targeting interferon or binding to annexin A1, or autoantibodies to phospholipids were seen. Moreover, the occurrence of autoimmune heparin induced thrombocytopenia has also been described in infected patients treated with heparin for controlling thrombogenicity.

This commentary focuses on the presence of various autoantibodies reported so far in Covid-19 diseases, exploring their association with the disease course and the durability of some related symptoms. Attempts are also made to further analyze the potential mechanism of actions and link the presence of antibodies with pathological complications.

Source: Amiral J, Seghatchian J. Autoimmune complications of COVID-19 and potential consequences for long-lasting disease syndromes. Transfus Apher Sci. 2022 Dec 17:103625. doi: 10.1016/j.transci.2022.103625. Epub ahead of print. PMID: 36585276; PMCID: PMC9757887. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9757887/ (Full text)

A scoping review of regulatory T cell dynamics in convalescent COVID-19 patients – indications for their potential involvement in the development of Long COVID?

Abstract:

Background: Recovery from coronavirus disease 2019 (COVID-19) can be impaired by the persistence of symptoms or new-onset health complications, commonly referred to as Long COVID. In a subset of patients, Long COVID is associated with immune system perturbations of unknown etiology, which could be related to compromised immunoregulatory mechanisms.

Objective: The objective of this scoping review was to summarize the existing literature regarding the frequency and functionality of Tregs in convalescent COVID-19 patients and to explore indications for their potential involvement in the development of Long COVID.

Design: A systematic search of studies investigating Tregs during COVID-19 convalescence was conducted on MEDLINE (via Pubmed) and Web of Science.

Results: The literature search yielded 17 relevant studies, of which three included a distinct cohort of patients with Long COVID. The reviewed studies suggest that the Treg population of COVID-19 patients can reconstitute quantitatively and functionally during recovery. However, the comparison between recovered and seronegative controls revealed that an infection-induced dysregulation of the Treg compartment can be sustained for at least several months. The small number of studies investigating Tregs in Long COVID allowed no firm conclusions to be drawn about their involvement in the syndrome’s etiology. Yet, even almost one year post-infection Long COVID patients exhibit significantly altered proportions of Tregs within the CD4+ T cell population.

Conclusions: Persistent alterations in cell frequency in Long COVID patients indicate that Treg dysregulation might be linked to immune system-associated sequelae. Future studies should aim to address the association of Treg adaptations with different symptom clusters and blood parameters beyond the sole quantification of cell frequencies while adhering to consensualized phenotyping strategies.

Source: Haunhorst S, Bloch W, Javelle F, Krüger K, Baumgart S, Drube S, Lemhöfer C, Reuken P, Stallmach A, Müller M, Zielinski CE, Pletz MW, Gabriel HHW, Puta C. A scoping review of regulatory T cell dynamics in convalescent COVID-19 patients – indications for their potential involvement in the development of Long COVID? Front Immunol. 2022 Dec 13;13:1070994. doi: 10.3389/fimmu.2022.1070994. PMID: 36582234; PMCID: PMC9792979. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9792979/ (Full text)

Long Covid: Untangling the Complex Syndrome and the Search for Therapeutics

Abstract:

Long Covid can affect anyone who has previously had acute COVID-19. The root causes of this syndrome are still unknown, and no effective therapeutics are available. This complex syndrome, with a wide array of symptoms, is still evolving. Given the dire situation, it is important to identify the causes of Long Covid and the changes occurring within the immune system of affected patients to figure out how to treat it.
The immune system intersects with the persistent viral fragments and blood clots that are implicated in this syndrome; understanding how these complex systems interact may help in untangling the puzzling physiopathology of Long Covid and identifying mitigation measures to provide patients some relief. In this paper, we discuss evidence-based findings and formulate hypotheses on the mechanisms underlying Long Covid’s physiopathology and propose potential therapeutic options.
Source: Haque A, Pant AB. Long Covid: Untangling the Complex Syndrome and the Search for Therapeutics. Viruses. 2023; 15(1):42. https://doi.org/10.3390/v15010042 https://www.mdpi.com/1999-4915/15/1/42 (Full text)