Tag: covid pathomechanism

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/

Pathological sequelae of long-haul COVID

Abstract:

The world continues to contend with successive waves of coronavirus disease 2019 (COVID-19), fueled by the emergence of viral variants. At the same time, persistent, prolonged and often debilitating sequelae are increasingly recognized in convalescent individuals, named ‘post-COVID-19 syndrome’ or ‘long-haul COVID’. Clinical symptomatology includes fatigue, malaise, dyspnea, defects in memory and concentration and a variety of neuropsychiatric syndromes as the major manifestations, and several organ systems can be involved. The underlying pathophysiological mechanisms are poorly understood at present.

This Review details organ-specific sequelae of post-COVID-19 syndromes and examines the underlying pathophysiological mechanisms available so far, elaborating on persistent inflammation, induced autoimmunity and putative viral reservoirs. Finally, we propose diagnostic strategies to better understand this heterogeneous disorder that continues to afflict millions of people worldwide.

Source: Mehandru, S., Merad, M. Pathological sequelae of long-haul COVID. Nat Immunol (2022). https://doi.org/10.1038/s41590-021-01104-y https://www.nature.com/articles/s41590-021-01104-y (Full text)

Immunological dysfunction persists for 8 months following initial mild-to-moderate SARS-CoV-2 infection

Abstract:

A proportion of patients surviving acute coronavirus disease 2019 (COVID-19) infection develop post-acute COVID syndrome (long COVID (LC)) lasting longer than 12 weeks. Here, we studied individuals with LC compared to age- and gender-matched recovered individuals without LC, unexposed donors and individuals infected with other coronaviruses. Patients with LC had highly activated innate immune cells, lacked naive T and B cells and showed elevated expression of type I IFN (IFN-β) and type III IFN (IFN-λ1) that remained persistently high at 8 months after infection.

Using a log-linear classification model, we defined an optimal set of analytes that had the strongest association with LC among the 28 analytes measured. Combinations of the inflammatory mediators IFN-β, PTX3, IFN-γ, IFN-λ2/3 and IL-6 associated with LC with 78.5–81.6% accuracy. This work defines immunological parameters associated with LC and suggests future opportunities for prevention and treatment.

Source: Phetsouphanh, C., Darley, D.R., Wilson, D.B. et al. Immunological dysfunction persists for 8 months following initial mild-to-moderate SARS-CoV-2 infection. Nat Immunol (2022). https://doi.org/10.1038/s41590-021-01113-x  (Full article)

Acute and chronic neurological disorders in COVID-19: potential mechanisms of disease

Abstract:

Coronavirus disease 2019 (COVID-19) is a global pandemic caused by SARS-CoV-2 infection and is associated with both acute and chronic disorders affecting the nervous system. Acute neurological disorders affecting patients with COVID-19 range widely from anosmia, stroke, encephalopathy/encephalitis, and seizures to Guillain-Barré syndrome. Chronic neurological sequelae are less well defined although exercise intolerance, dysautonomia, pain, as well as neurocognitive and psychiatric dysfunctions are commonly reported. Molecular analyses of CSF and neuropathological studies highlight both vascular and immunologic perturbations.

Low levels of viral RNA have been detected in the brains of few acutely ill individuals. Potential pathogenic mechanisms in the acute phase include coagulopathies with associated cerebral hypoxic-ischaemic injury, blood-brain barrier abnormalities with endotheliopathy and possibly viral neuroinvasion accompanied by neuro-immune responses. Established diagnostic tools are limited by a lack of clearly defined COVID-19 specific neurological syndromes. Future interventions will require delineation of specific neurological syndromes, diagnostic algorithm development and uncovering the underlying disease mechanisms that will guide effective therapies.

Source: Balcom EF, Nath A, Power C. Acute and chronic neurological disorders in COVID-19: potential mechanisms of disease. Brain. 2021 Dec 31;144(12):3576-3588. doi: 10.1093/brain/awab302. PMID: 34398188; PMCID: PMC8719840. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8719840/ (Full text)

Could SARS-CoV-2 Spike Protein Be Responsible for Long-COVID Syndrome?

Abstract:

SARS-CoV-2 infects cells via its spike protein binding to its surface receptor on target cells and results in acute symptoms involving especially the lungs known as COVID-19. However, increasing evidence indicates that many patients develop a chronic condition characterized by fatigue and neuropsychiatric symptoms, termed long-COVID. Most of the vaccines produced so far for COVID-19 direct mammalian cells via either mRNA or an adenovirus vector to express the spike protein, or administer recombinant spike protein, which is recognized by the immune system leading to the production of neutralizing antibodies.

Recent publications provide new findings that may help decipher the pathogenesis of long-COVID. One paper reported perivascular inflammation in brains of deceased patients with COVID-19, while others showed that the spike protein could damage the endothelium in an animal model, that it could disrupt an in vitro model of the blood-brain barrier (BBB), and that it can cross the BBB resulting in perivascular inflammation. Moreover, the spike protein appears to share antigenic epitopes with human molecular chaperons resulting in autoimmunity and can activate toll-like receptors (TLRs), leading to release of inflammatory cytokines.

Moreover, some antibodies produced against the spike protein may not be neutralizing, but may change its conformation rendering it more likely to bind to its receptor. As a result, one wonders whether the spike protein entering the brain or being expressed by brain cells could activate microglia, alone or together with inflammatory cytokines, since protective antibodies could not cross the BBB, leading to neuro-inflammation and contributing to long-COVID.

Hence, there is urgent need to better understand the neurotoxic effects of the spike protein and to consider possible interventions to mitigate spike protein-related detrimental effects to the brain, possibly via use of small natural molecules, especially the flavonoids luteolin and quercetin.

Source: Theoharides TC. Could SARS-CoV-2 Spike Protein Be Responsible for Long-COVID Syndrome? Mol Neurobiol. 2022 Jan 13:1–12. doi: 10.1007/s12035-021-02696-0. Epub ahead of print. PMID: 35028901; PMCID: PMC8757925. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8757925/ (Full text)

“LONG COVID”-A hypothesis for understanding the biological basis and pharmacological treatment strategy

Abstract:

Infection of humans with SARS-CoV-2 virus causes a disease known colloquially as “COVID-19” with symptoms ranging from asymptomatic to severe pneumonia. Initial pathology is due to the virus binding to the ACE-2 protein on endothelial cells lining blood vessels and entering these cells in order to replicate. Viral replication causes oxidative stress due to elevated levels of reactive oxygen species. Many (~60%) of the infected people appear to have eliminated the virus from their body after 28 days and resume normal activity. However, a significant proportion (~40%) experience a variety of symptoms (loss of smell and/or taste, fatigue, cough, aching pain, “brain fog,” insomnia, shortness of breath, and tachycardia) after 12 weeks and are diagnosed with a syndrome named “LONG COVID.”

Longitudinal clinical studies in a group of subjects who were infected with SARS-CoV-2 have been compared to a non-infected matched group of subjects. A cohort of infected subjects can be identified by a battery of cytokine markers to have persistent, low level grade of inflammation and often self-report two or more troubling symptoms. There is no drug that will relieve their symptoms effectively.

It is hypothesized that drugs that activate the intracellular transcription factor, nuclear factor erythroid-derived 2-like 2 (NRF2) may increase the expression of enzymes to synthesize the intracellular antioxidant, glutathione that will quench free radicals causing oxidative stress. The hormone melatonin has been identified as an activator of NRF2 and a relatively safe chemical for most people to ingest chronically. Thus, it is an option for consideration of re-purposing studies in “LONG COVID” subjects experiencing insomnia, depression, fatigue, and “brain fog” but not tachycardia. Appropriately designed clinical trials are required to evaluate melatonin.

Source: Jarrott B, Head R, Pringle KG, Lumbers ER, Martin JH. “LONG COVID”-A hypothesis for understanding the biological basis and pharmacological treatment strategy. Pharmacol Res Perspect. 2022 Feb;10(1):e00911. doi: 10.1002/prp2.911. PMID: 35029046. https://bpspubs.onlinelibrary.wiley.com/doi/10.1002/prp2.911 (Full text)

Nervous system consequences of COVID-19

Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is considered a respiratory pathogen, myriad neurologic complications—including confusion, stroke, and neuromuscular disorders—manifest during acute COVID-19. Furthermore, maladies such as impaired concentration, headache, sensory disturbances, depression, and even psychosis may persist for months after infection, as part of a constellation of symptoms now called Long Covid. Even young people with mild initial disease can develop acute COVID-19 and Long Covid neuropsychiatric syndromes. The pathophysiological mechanisms are not well understood, although evidence primarily implicates immune dysfunction, including nonspecific neuroinflammation and antineural autoimmune dysregulation. It is uncertain whether unforeseen neurological consequences may develop years after initial infection. With millions of individuals affected, nervous system complications pose public health challenges for rehabilitation and recovery and for disruptions in the workforce due to loss of functional capacity. There is an urgent need to understand the pathophysiology of these disorders and develop disease-modifying therapies.

Read the rest of this article HERE.

Source: Serena Spudich and Avindra Nath. Nervous system consequences of COVID-19. Science, Volume 375 | Issue 6578, 21 January 2022.

A Machine-Generated View of the Role of Blood Glucose Levels in the Severity of COVID-19

Abstract:

SARS-CoV-2 started spreading toward the end of 2019 causing COVID-19, a disease that reached pandemic proportions among the human population within months. The reasons for the spectrum of differences in the severity of the disease across the population, and in particular why the disease affects more severely the aging population and those with specific preconditions are unclear. We developed machine learning models to mine 240,000 scientific articles openly accessible in the CORD-19 database, and constructed knowledge graphs to synthesize the extracted information and navigate the collective knowledge in an attempt to search for a potential common underlying reason for disease severity. The machine-driven framework we developed repeatedly pointed to elevated blood glucose as a key facilitator in the progression of COVID-19. Indeed, when we systematically retraced the steps of the SARS-CoV-2 infection, we found evidence linking elevated glucose to each major step of the life-cycle of the virus, progression of the disease, and presentation of symptoms.

Specifically, elevations of glucose provide ideal conditions for the virus to evade and weaken the first level of the immune defense system in the lungs, gain access to deep alveolar cells, bind to the ACE2 receptor and enter the pulmonary cells, accelerate replication of the virus within cells increasing cell death and inducing an pulmonary inflammatory response, which overwhelms an already weakened innate immune system to trigger an avalanche of systemic infections, inflammation and cell damage, a cytokine storm and thrombotic events. We tested the feasibility of the hypothesis by manually reviewing the literature referenced by the machine-generated synthesis, reconstructing atomistically the virus at the surface of the pulmonary airways, and performing quantitative computational modeling of the effects of glucose levels on the infection process.

We conclude that elevation in glucose levels can facilitate the progression of the disease through multiple mechanisms and can explain much of the differences in disease severity seen across the population. The study provides diagnostic considerations, new areas of research and potential treatments, and cautions on treatment strategies and critical care conditions that induce elevations in blood glucose levels.

Source: Logette E, Lorin C, Favreau C, et al. A Machine-Generated View of the Role of Blood Glucose Levels in the Severity of COVID-19. Front Public Health. 2021;9:695139. Published 2021 Jul 28. doi:10.3389/fpubh.2021.695139 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8356061/ (Full text)

Endothelial dysfunction is the key of long COVID-19 symptoms: The results of TUN-EndCOV study

Abstract:

Background: The COVID-19 disease is a multisystem disease due to in part to the vascular endothelium injury. Lasting effects and long-term sequalae could persist after the infection and may be due to persistent endothelial dysfunction.

Purpose: Our study focused on the study of endothelial function measurement by digital thermal monitoring (DTM) of endothelial quality index with E4 diagnosis Polymath in a large cohort of long COVID-19 patients to determine whether long COVID-19 symptoms are due to endothelial dysfunction.

Methods: This is a prospective multicenter longitudinal observational cohort study. Endothelial function was evaluated with “E4-Diagnose” Polymath Tunisia based on the Endothelium Quality Index (EQI). A complete echocardiographic evaluation analysis was performed. Primary outcomes were defined as the occurrence of long COVID-19 symptoms in patients with endothelial dysfunction measured by EQI.

Results: A total of 798 patients were included in this study. Patients were included at an average time of 68.93 ± 43.1 days. The mean EQI was 2.02 ± 0.99 [0–5]. A total of 397 (49.7%) patients had poor or very poor EQI and 211 (26.4%) patients had very poor EQI. The median age was 49.94 ± 14.2 (18–80) years. A total of 618 patients (77.4%) had long COVID-19 symptoms. Patients with long COVID-19 symptoms had a reduced EQI (1.99 ± 0.97 vs. 2.09 ± 1.05, P = 0.24). Among long COVID-19 symptoms, fatigue was the most common symptom reported in 42.2%. Fatigue and chest pain were significantly associated to the endothelial dysfunction (P = 0.04 and 0.001 respectively). Patients with chest pain had significantly lower EQI (1.74 ± 1.0 vs. 2.09 ± 0.9, P ≤ 10−3) and LVGLS (−16.35 ± 3.0 vs. −17.16 ± 2.5, P = 0.04).

Conclusion: Long COVID-19 symptoms specifically chest pain and fatigue are due to persistent poor endothelial quality index. These findings allow a better care of patients with long COVID-19 symptoms.

Source: S. Charfeddine, H. Ibnhadjamor, S. Torjmen, S. Kraiem, R. Hammami, A. Bahloul, N. Kallel, N. Moussa, I. Touil, S. Milouchi, J. Elghoul, Z. Meddeb, Y. Thabet, J. Jdidi, K. Bouslema, S. Abdesselem, L. Abid. Endothelial dysfunction is the key of long COVID-19 symptoms: The results of TUN-EndCOV study. Archives of Cardiovascular Diseases Supplements, Volume 14, Issue 1, 2022, Page 126, ISSN 1878-6480, https://doi.org/10.1016/j.acvdsp.2021.10.004. (https://www.sciencedirect.com/science/article/pii/S187864802100642X)

Diverse functional autoantibodies in patients with COVID-19

Abstract:

COVID-19 manifests with a wide spectrum of clinical phenotypes that are characterized by exaggerated and misdirected host immune responses1-6. Although pathological innate immune activation is well-documented in severe disease1, the effect of autoantibodies on disease progression is less well-defined. Here we use a high-throughput autoantibody discovery technique known as rapid extracellular antigen profiling7 to screen a cohort of 194 individuals infected with SARS-CoV-2, comprising 172 patients with COVID-19 and 22 healthcare workers with mild disease or asymptomatic infection, for autoantibodies against 2,770 extracellular and secreted proteins (members of the exoproteome).

We found that patients with COVID-19 exhibit marked increases in autoantibody reactivities as compared to uninfected individuals, and show a high prevalence of autoantibodies against immunomodulatory proteins (including cytokines, chemokines, complement components and cell-surface proteins). We established that these autoantibodies perturb immune function and impair virological control by inhibiting immunoreceptor signalling and by altering peripheral immune cell composition, and found that mouse surrogates of these autoantibodies increase disease severity in a mouse model of SARS-CoV-2 infection. Our analysis of autoantibodies against tissue-associated antigens revealed associations with specific clinical characteristics. Our findings suggest a pathological role for exoproteome-directed autoantibodies in COVID-19, with diverse effects on immune functionality and associations with clinical outcomes.

Source: Wang EY, Mao T, Klein J, Dai Y, Huck JD, Jaycox JR, Liu F, Zhou T, Israelow B, Wong P, Coppi A, Lucas C, Silva J, Oh JE, Song E, Perotti ES, Zheng NS, Fischer S, Campbell M, Fournier JB, Wyllie AL, Vogels CBF, Ott IM, Kalinich CC, Petrone ME, Watkins AE; Yale IMPACT Team, Dela Cruz C, Farhadian SF, Schulz WL, Ma S, Grubaugh ND, Ko AI, Iwasaki A, Ring AM. Diverse functional autoantibodies in patients with COVID-19. Nature. 2021 Jul;595(7866):283-288. doi: 10.1038/s41586-021-03631-y. Epub 2021 May 19. PMID: 34010947. https://pubmed.ncbi.nlm.nih.gov/34010947/