Hypercoagulability, endotheliopathy, and inflammation approximating 1 year after recovery: Assessing the long-term outcomes in COVID-19 patients

Inflammatory risk contributes to post-COVID endothelial dysfunction through anti-ACKR1 autoantibody

Subclinical vascular impairment can be exacerbated in individuals who experience sustained inflammation after COVID-19 infection. Our study explores the prevalence and impact of autoantibodies on vascular dysfunction in healthy COVID-19 survivors, an area that remains inadequately investigated. Focusing on autoantibodies against the atypical chemokine receptor 1 (ACKR1), COVID-19 survivors demonstrated significantly elevated anti-ACKR1 autoantibodies, correlating with systemic cytokines, circulating damaged endothelial cells, and endothelial dysfunction. An independent cohort linked these autoantibodies to increased vascular disease outcomes during a median 6.7-yr follow-up. We analyzed a single-cell transcriptome atlas of endothelial cells from diverse mouse tissues, identifying enriched Ackr1 expressions in venous regions of the brain and soleus muscle vasculatures, which holds intriguing implications for tissue-specific venous thromboembolism manifestations reported in COVID-19. Functionally, purified immunoglobulin G (IgG) extracted from patient plasma did not trigger cell apoptosis or increase barrier permeability in human vein endothelial cells. Instead, plasma IgG enhanced antibody-dependent cellular cytotoxicity mediated by patient PBMCs, a phenomenon alleviated by blocking peptide or liposome ACKR1 recombinant protein. The blocking peptide uncovered that purified IgG from COVID-19 survivors possessed potential epitopes in the N-terminal extracellular domain of ACKR1, which effectively averted antibody-dependent cellular cytotoxicity. Our findings offer insights into therapeutic development to mitigate autoantibody reactivity in blood vessels in chronic inflammation.

Endothelial dysfunction and persistent inflammation in severe post-COVID-19 patients: implications for gas exchange

BACKGROUND

Understanding the enduring respiratory consequences of severe COVID-19 is crucial for comprehensive patient care. This study aims to evaluate the impact of post-COVID conditions on respiratory sequelae of severe acute respiratory distress syndrome (ARDS).

METHODS

We examined 88 survivors of COVID-19-associated severe ARDS six months post-intensive care unit (ICU) discharge. Assessments included clinical and functional evaluation as well as plasma biomarkers of endothelial dysfunction, inflammation, and viral response. Additionally, an in vitro model using human umbilical vein endothelial cells (HUVECs) explored the direct impact of post-COVID plasma on endothelial function.

RESULTS

Post-COVID patients with impaired gas exchange demonstrated persistent endothelial inflammation marked by elevated ICAM-1, IL-8, CCL-2, and ET-1 plasma levels. Concurrently, systemic inflammation, evidenced by NLRP3 overexpression and elevated levels of IL-6, sCD40-L, and C-reactive protein, was associated with endothelial dysfunction biomarkers and increased in post-COVID patients with impaired gas exchange. T-cell activation, reflected in CD69 expression, and persistently elevated levels of interferon-β (IFN-β) further contributed to sustained inflammation. The in vitro model confirmed that patient plasma, with altered levels of sCD40-L and IFN-β proteins, has the capacity to alter endothelial function.

CONCLUSIONS

Six months post-ICU discharge, survivors of COVID-19-associated ARDS exhibited sustained elevation in endothelial dysfunction biomarkers, correlating with the severity of impaired gas exchange. NLRP3 inflammasome activity and persistent T-cell activation indicate on going inflammation contributing to persistent endothelial dysfunction, potentially intensified by sustained viral immune response.

What Role Does Microthrombosis Play in Long COVID?

Soon after the outbreak of coronavirus disease 2019 (COVID-19), unexplained sustained fatigue, cognitive disturbance, and muscle ache/weakness were reported in patients who had recovered from acute COVID-19 infection. This abnormal condition has been recognized as "long COVID (postacute sequelae of COVID-19 [PASC])" with a prevalence estimated to be from 10 to 20% of convalescent patients. Although the pathophysiology of PASC has been studied, the exact mechanism remains obscure. Microclots in circulation can represent one of the possible causes of PASC. Although hypercoagulability and thrombosis are critical mechanisms of acute COVID-19, recent studies have reported that thromboinflammation continues in some patients, even after the virus has cleared. Viral spike proteins and RNA can be detected months after patients have recovered, findings that may be responsible for persistent thromboinflammation and the development of microclots. Despite this theory, long-term results of anticoagulation, antiplatelet therapy, and vascular endothelial protection are inconsistent, and could not always show beneficial treatment effects. In summary, PASC reflects a heterogeneous condition, and microclots cannot explain all the presenting symptoms. After clarification of the pathomechanisms of each symptom, a symptom- or biomarker-based stratified approach should be considered for future studies.

COVID-19 and Long-COVID Thrombosis: From Clinical and Basic Science to Therapeutics

Coronavirus infectious disease-19 (COVID-19) is a pandemic characterized by serious lung disease and thrombotic events in the venous and circulation trees, which represent a harmful clinical sign of poor outcome. Thrombotic events are more frequent in patients with severe disease requiring intensive care units and are associated with platelet and clotting activation. However, after resolution of acute infection, patients may still have clinical sequelae, the so-called long-COVID-19, including thrombotic events again in the venous and arterial circulation. The mechanisms accounting for thrombosis in acute and long COVID-19 have not been fully clarified; interactions of COVID-19 with angiotensin converting enzyme 2 or toll-like receptor family or infection-induced cytokine storm have been suggested to be implicated in endothelial cells, leucocytes, and platelets to elicit clotting activation in acute as well in chronic phase of the disease. In acute COVID-19, prophylactic or full doses of anticoagulants exert beneficial effects even if the dosage choice is still under investigation; however, a residual risk still remains suggesting a need for a more appropriate therapeutic approach. In long COVID-19 preliminary data provided useful information in terms of antiplatelet treatment but definition of candidates for thrombotic prophylaxis is still undefined.

Coagulation profile in hospitalized children with COVID-19: pediatric age dependency and its impact on long COVID development

Introduction

Pulmonary endotheliopathy and microvascular immunothrombosis play a key role in acute COVID-19. Moreover, persistent endotheliopathy and heightened coagulability frequently occur in individuals recovering from COVID-19, suggesting the intriguing possibility of their role in the development of long COVID. The aim of our study was to investigate the coagulation profile in patients with COVID-19 based on age and their role in the development of long COVID.

Methods

We conducted a prospective single-center cohort study from September 2022 to August 2023. The study involved 190 patients younger than 18 years who were hospitalized at the Ternopil City Children's Hospital, Ukraine due to COVID-19. Patients underwent determination of coagulation profile in addition to the general clinical examination. After discharge from the hospital, patients were monitored for the presence of long COVID symptoms. Among the 157 participants who consented for follow-up, 62 patients (39.5%) had long COVID symptoms according to the WHO definition, while the rest (95 patients) did not have symptoms of long COVID (fully recovered).

Results

The study revealed the normal count of platelets in the majority of patients (86.8%), whereas abnormalities in the coagulation profile were revealed in 94.5% of children with COVID-19, and these changes were age-dependent. The patients were mostly presented with increased activated partial thromboplastin time (69.1%), prothrombin time (PT) (39.8%) and D-dimer (45.0%). There was no significant difference between the median of platelet levels and coagulation profile indicators between the groups with long COVID and recovered. Among children who developed persistent long COVID symptoms there was a statistically higher percentage of abnormal PT values (53% versus 36.1%, p=0.0432), with no significant differences in other coagulation profile indicators. Abnormal PT along with female gender, comorbidities, especially allergic pathology, nutritional disorder, including obesity, were determined as potential risk factors of the long COVID development (Odds ratio - 2.0611; 95% 1.0179-4.1737, p=0.0445).

Conclusions

The study highlights the need for more extensive research into the coagulation profiles of pediatric populations, considering age-specific factors. This could enhance our understanding of thromboinflammation in COVID-19 and its potential contribution to the development of persistent symptoms.

Superior Ophthalmic Vein Thrombosis Associated With Asymptomatic COVID-19 Infection

Superior ophthalmic vein thrombosis is a rare condition scarcely described in clinical literature with potentially severe consequences including permanent vision loss. This report details the case of a 70-year-old woman who presented with acute binocular horizontal diplopia, relative proptosis of the OD by 4 mm, and pain OD. On exam, visual acuity was 20/20 OD and 20/30 OS with full extraocular movements. CT revealed proptosis OD with a thrombosed superior ophthalmic varix. Evaluation for etiology of hypercoagulability was unremarkable, although the patient did have an asymptomatic COVID-19 infection 1 month prior. To the authors' knowledge, this is the first reported case of superior ophthalmic vein thrombosis secondary to an asymptomatic COVID-19 infection.

VEGF-A plasma levels are associated with impaired DLCO and radiological sequelae in long COVID patients

BACKGROUND

Long COVID, also known as post-acute sequelae of COVID-19 (PASC), is characterized by persistent clinical symptoms following COVID-19.

OBJECTIVE

To correlate biomarkers of endothelial dysfunction with persistent clinical symptoms and pulmonary function defects at distance from COVID-19.

METHODS

Consecutive patients with long COVID-19 suspicion were enrolled. A panel of endothelial biomarkers was measured in each patient during clinical evaluation and pulmonary function test (PFT).

RESULTS

The study included 137 PASC patients, mostly male (68%), with a median age of 55 years. A total of 194 PFTs were performed between months 3 and 24 after an episode of SARS-CoV-2 infection. We compared biomarkers evaluated in PASC patients with 20 healthy volunteers (HVs) and acute hospitalized COVID-19 patients (n = 88). The study found that angiogenesis-related biomarkers and von Willebrand factor (VWF) levels were increased in PASC patients compared to HVs without increased inflammatory or platelet activation markers. Moreover, VEGF-A and VWF were associated with persistent lung CT scan lesions and impaired diffusing capacity of the lungs for carbon monoxide (DLCO) measurement. By employing a Cox proportional hazards model adjusted for age, sex, and body mass index, we further confirmed the accuracy of VEGF-A and VWF. Following adjustment, VEGF-A emerged as the most significant predictive factor associated with persistent lung CT scan lesions and impaired DLCO measurement.

CONCLUSION

VEGF-A is a relevant predictive factor for DLCO impairment and radiological sequelae in PASC. Beyond being a biomarker, we hypothesize that the persistence of angiogenic disorders may contribute to long COVID symptoms.

Damage to endothelial barriers and its contribution to long COVID

The world continues to contend with COVID-19, fueled by the emergence of viral variants. At the same time, a subset of convalescent individuals continues to experience persistent and prolonged sequelae, known as long COVID. Clinical, autopsy, animal and in vitro studies all reveal endothelial injury in acute COVID-19 and convalescent patients. Endothelial dysfunction is now recognized as a central factor in COVID-19 progression and long COVID development. Different organs contain different types of endothelia, each with specific features, forming different endothelial barriers and executing different physiological functions. Endothelial injury results in contraction of cell margins (increased permeability), shedding of glycocalyx, extension of phosphatidylserine-rich filopods, and barrier damage. During acute SARS-CoV-2 infection, damaged endothelial cells promote diffuse microthrombi and destroy the endothelial (including blood-air, blood-brain, glomerular filtration and intestinal-blood) barriers, leading to multiple organ dysfunction. During the convalescence period, a subset of patients is unable to fully recover due to persistent endothelial dysfunction, contributing to long COVID. There is still an important knowledge gap between endothelial barrier damage in different organs and COVID-19 sequelae. In this article, we mainly focus on these endothelial barriers and their contribution to long COVID.

Long COVID: Molecular Mechanisms and Detection Techniques

Long COVID, also known as post-acute sequelae of SARS-CoV-2 infection (PASC), has emerged as a significant health concern following the COVID-19 pandemic. Molecular mechanisms underlying the occurrence and progression of long COVID include viral persistence, immune dysregulation, endothelial dysfunction, and neurological involvement, and highlight the need for further research to develop targeted therapies for this condition. While a clearer picture of the clinical symptomatology is shaping, many molecular mechanisms are yet to be unraveled, given their complexity and high level of interaction with other metabolic pathways. This review summarizes some of the most important symptoms and associated molecular mechanisms that occur in long COVID, as well as the most relevant molecular techniques that can be used in understanding the viral pathogen, its affinity towards the host, and the possible outcomes of host-pathogen interaction.

Sex Differences and Cytokine Profiles among Patients Hospitalized for COVID-19 and during Their Recovery: The Predominance of Adhesion Molecules in Females and Oxidative Stress in Males

The severity and mortality of coronavirus disease 2019 (COVID-19) are greater in males than in females, though the infection rate is the same in the two sexes. We investigated sex hormone differences associated with the hyperinflammatory immune response to SARS-CoV-2 on the basis of patients' cytokine profiles and vaccination statuses. Clinical and laboratory data of 117 patients with COVID-19 were collected to examine sex differences associated with oxidative stress markers, neutrophil extracellular traps (NETs), and plasma cytokine levels up to 5 months from hospital admission. The testosterone and free testosterone levels were low in male patients with COVID-19 and returned to normal values after recovery from the disease. The dihydrotestosterone (DHT) levels were transiently reduced, while the sex hormone-binding globulin levels were decreased in post-COVID-19 male patients. The levels of the inflammatory cytokines interleukin-6 (IL-6) and IL-10 appeared generally increased at diagnosis and decreased in post-COVID-19 patients. In females, the concentration of tumor necrosis factor-alpha was increased by four times at diagnosis. The levels of the coagulation markers intercellular adhesion molecule-1 (ICAM-1) and E-selectin were consistently upregulated in post-COVID-19 female patients, in contrast to those of vascular cell adhesion molecule-1 (VCAM-1), P-selectin, and chemokine IL-8. DHT increased the levels of reactive oxygen species in the neutrophils of male patients, while estradiol decreased them in females. Markers for NET, such as circulating DNA and myeloperoxidase, were significantly more abundant in the patients' plasma. Sex hormones have a potential protective role during SARS-CoV-2 infection, which is weakened by impaired testosterone synthesis in men.

Uncertainties about the roles of anticoagulation and microclots in postacute sequelae of severe acute respiratory syndrome coronavirus 2 infection

Three years after the start of the pandemic, approaches to the prevention and treatment of acute COVID-19 have been established. However, postacute sequelae of SARS-CoV-2 infection (PASC) is now the focus of current investigations searching for the etiology of the symptoms and developing diagnostic and treatment strategies, as up to 10% of those with acute COVID-19 will go on to develop PASC, a significant public health burden. Some have suggested that ongoing microvascular thrombosis and microclots may play a role in the persistent sequelae of COVID-19 infection. Treatments are being given to address the presumed role of thrombosis in PASC, and some suggest that randomized controlled trials of anticoagulants in patients with PASC should be performed. In this Forum article, we focus on findings from patients with PASC that have led to the suggestion of using anticoagulants and discuss alternative considerations.

Endothelium dysfunction and thrombosis in COVID-19 with type 2 diabetes

SARS-CoV-2 can directly or indirectly damage endothelial cells. Endothelial injury, especially phosphatidylserine (PS) exposure on the outer membrane of cells, can more easily promote thrombosis. Type 2 diabetes(T2D) patients were more susceptible to COVID-19, they had more severe symptoms, higher risk of thrombotic complications, and longer duration of post-COVID-19 sequelae. This review provided a detailed overview of the mechanisms underlying endothelial dysfunction in T2D patients with COVID-19 (including long COVID), which may be influenced by hyperglycemia, hypoxia, and pro-inflammatory environments. The mechanisms of thrombosis in T2D patients with COVID-19 are also explored, particularly the effects of increased numbers of PS-exposing particles, blood cells, and endothelial cells on hypercoagulability. Given the high risk of thrombosis in T2D patients with COVID-19, early antithrombotic therapy can both minimize the impact of the disease on patients and maximize the chances of improvement, thereby alleviating patient suffering. We provided detailed guidance on antithrombotic drugs and dosages for mild, moderate, and severe patients, emphasizing that the optimal timing of thromboprophylaxis is a critical factor in influencing prognosis. Considering the potential interactions between antidiabetic, anticoagulant, and antiviral drugs, we proposed practical and comprehensive management recommendations to supplement the incomplete efficacy of vaccines in the diabetic population, reduce the incidence of post-COVID-19 sequelae, and improve patient quality of life.

Persistent Endothelial Lung Damage and Impaired Diffusion Capacity in Long COVID

Since the beginning of the pandemic, both COVID-19-associated coagulopathy biomarkers and a plethora of endothelial biomarkers have been proposed and tested as prognostic tools of severity and mortality prediction. As the pandemic is gradually being controlled, attention is now focusing on the long-term sequelae of COVID-19. In the present study, we investigated the role of endothelial activation/dysfunction in long COVID syndrome. This observational study included 68 consecutive long COVID patients and a healthy age and sex-matched control group. In both groups, we measured 13 endothelial biomarkers. Moreover, in the long COVID patients, we evaluated fatigue and dyspnea severity, lung diffusion capacity (DLCO), and the 6-min walk (6MWT) test as measures of functional capacity. Our results showed that markers of endothelial activation/dysfunction were higher in long COVID patients, and that soluble intracellular adhesion molecule 1 (sICAM-1) and soluble vascular adhesion molecule 1 (sVCAM-1) negatively correlated with lung diffusion and functional capacity (sICAM-1 vs. DLCO, r = -0.306, p = 0.018; vs. 6MWT, r = -0.263, p = 0.044; and sVCAM-1 vs. DLCO, r= -0.346, p = 0.008; vs. 6MWT, r = -0.504, p < 0.0001). In conclusion, evaluating endothelial biomarkers alongside clinical tests might yield more specific insights into the pathophysiological mechanisms of long COVID manifestations.

Fatigue in Post-Acute Sequelae of Coronavirus Disease 2019

Fatigue from post-acute sequelae of coronavirus disease 2019 is a complex constellation of symptoms that could be driven by a wide spectrum of underlying etiologies. Despite this, there seems to be hope for treatment plans that focus on addressing possible etiologies and creating a path to improving quality of life and a paced return to activity.

Hematological alterations associated with long COVID-19

Long COVID-19 is a condition characterized by persistent symptoms lasting beyond the acute phase of COVID-19. Long COVID-19 produces diverse symptomatology and can impact organs and systems, including the hematological system. Several studies have reported, in COVID-19 patients, hematological abnormalities. Most of these alterations are associated with a higher risk of severe disease and poor outcomes. This literature review identified studies reporting hematological parameters in individuals with Long COVID-19. Findings suggest that Long COVID-19 is associated with a range of sustained hematological alterations, including alterations in red blood cells, anemia, lymphopenia, and elevated levels of inflammatory markers such as ferritin, D-dimer, and IL-6. These alterations may contribute to a better understanding of the pathophysiology of Long COVID-19 and its associated symptoms. However, further research is needed to elucidate the underlying mechanisms and potential treatments for these hematological changes in individuals with Long COVID-19.

Long-term hypercoagulability, endotheliopathy and inflammation following acute SARS-CoV-2 infection

INTRODUCTION

both symptomatic and asymptomatic SARS-CoV-2 infections - coined Coronavirus disease 2019 (COVID-19) - have been linked to a higher risk of cardiovascular events after recovery.

AREAS COVERED

our review aims to summarize the latest evidence on the increased thrombotic and cardiovascular risk in recovered COVID-19 patients and to examine the pathophysiological mechanisms underlying the interplay among endothelial dysfunction, inflammatory response and coagulation in long-COVID. We performed a systematic search of studies on hypercoagulability, endothelial dysfunction and inflammation after SARS-CoV-2 infection.

EXPERT OPINION

endothelial dysfunction is a major pathophysiological mechanism responsible for most clinical manifestations in COVID-19. The pathological activation of endothelial cells by a virus infection results in a pro-adhesive and chemokine-secreting phenotype, which in turn promotes the recruitment of circulating leukocytes. Cardiovascular events after COVID-19 appear to be related to persistent immune dysregulation. Patients with long-lasting symptoms display higher amounts of proinflammatory molecules such as tumor necrosis factor-α, interferon γ and interleukins 2 and 6. Immune dysregulation can trigger the activation of the coagulation pathway. The formation of extensive microclots in vivo, both during acute COVID-19 and in long-COVID-19, appears to be a relevant mechanism responsible for persistent symptoms and cardiovascular events.

Laboratory Findings and Biomarkers in Long COVID: What Do We Know So Far? Insights into Epidemiology, Pathogenesis, Therapeutic Perspectives and Challenges

Long COVID (LC) encompasses a constellation of long-term symptoms experienced by at least 10% of people after the initial SARS-CoV-2 infection, and so far it has affected about 65 million people. The etiology of LC remains unclear; however, many pathophysiological pathways may be involved, including viral persistence; a chronic, low-grade inflammatory response; immune dysregulation and a defective immune response; the reactivation of latent viruses; autoimmunity; persistent endothelial dysfunction and coagulopathy; gut dysbiosis; hormonal and metabolic dysregulation; mitochondrial dysfunction; and autonomic nervous system dysfunction. There are no specific tests for the diagnosis of LC, and clinical features including laboratory findings and biomarkers may not specifically relate to LC. Therefore, it is of paramount importance to develop and validate biomarkers that can be employed for the prediction, diagnosis and prognosis of LC and its therapeutic response, although this effort may be hampered by challenges pertaining to the non-specific nature of the majority of clinical manifestations in the LC spectrum, small sample sizes of relevant studies and other methodological issues. Promising candidate biomarkers that are found in some patients are markers of systemic inflammation, including acute phase proteins, cytokines and chemokines; biomarkers reflecting SARS-CoV-2 persistence, the reactivation of herpesviruses and immune dysregulation; biomarkers of endotheliopathy, coagulation and fibrinolysis; microbiota alterations; diverse proteins and metabolites; hormonal and metabolic biomarkers; and cerebrospinal fluid biomarkers. At present, there are only two reviews summarizing relevant biomarkers; however, they do not cover the entire umbrella of current biomarkers, their link to etiopathogenetic mechanisms or the diagnostic work-up in a comprehensive manner. Herein, we aim to appraise and synopsize the available evidence on the typical laboratory manifestations and candidate biomarkers of LC, their classification based on pathogenetic mechanisms and the main LC symptomatology in the frame of the epidemiological and clinical aspects of the syndrome and furthermore assess limitations and challenges as well as potential implications in candidate therapeutic interventions.

Endotheliopathy in Acute COVID-19 and Long COVID

The pulmonary endothelium is a highly regulated organ that performs a wide range of functions under physiological and pathological conditions. Since endothelial dysfunction has been demonstrated to play a direct role in sepsis and acute respiratory distress syndrome, its role in COVID-19 has also been extensively investigated. Indeed, apart from the COVID-19-associated coagulopathy biomarkers, new biomarkers were recognised early during the pandemic, including markers of endothelial cell activation or injury. We systematically searched the literature up to 10 March 2023 for studies examining the association between acute and long COVID-19 severity and outcomes and endothelial biomarkers.

The Long Term Residual Effects of COVID-Associated Coagulopathy

During the acute phase of COVID-19, many patients experience a complex coagulopathy characterized by a procoagulant pattern. The present study investigates the persistence of hemostatic changes in post-COVID patients at a long-term follow up, and the link with the persistence of physical and neuropsychological symptoms. We completed a prospective cohort study on 102 post-COVID patients. Standard coagulation and viscoelastic tests were performed, along with an assessment of persistent symptoms and recording of acute phase details. A procoagulant state was adjudicated in the presence of fibrinogen > 400 mg/dL, or D-dimer > 500 ng/mL, or platelet count > 450,000 cells/µL, or a maxim clot lysis at viscoelastic test < 2%. A procoagulant state was identified in 75% of the patients at 3 months follow up, 50% at 6 months, and 30% at 12–18 months. Factors associated with the persistence of a procoagulant state were age, severity of the acute phase, and persistence of symptoms. Patients with major physical symptoms carry a procoagulant state relative risk of 2.8 (95% confidence interval 1.17–6.7, p = 0.019). The association between persistent symptoms and a procoagulant state raises the hypothesis that an ongoing process of thrombi formation and/or persistent microthrombosis may be responsible for the main physical symptoms in long-COVID patients.

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

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.

Immune and coagulation profiles in 3 adults with multisystem inflammatory syndrome

Introduction: There is a paucity of information on the cytokine, complement, endothelial activation, and coagulation profiles of multisystem inflammatory syndrome in adults (MIS-A), a rare but serious complication following recovery from SARS-CoV-2 infection. We aim to examine the immune biomarker and coagulation profiles in association with the clinical presentation and course of MIS-A. Method: The clinical features of MIS-A patients admitted to our tertiary hospital were documented. Their levels of interleukin (IL)-1β, IL-6, IL-10, IL-17, IL-18, interferon-α (IFN-α), IFN-γ, interferon gamma-induced protein 10 (IP-10), tumour necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, complement activation product (complement 5a [C5a]), and endothelial biomarker intercellular adhesion molecule-1 (ICAM-1) levels were assayed. The haemostatic profile was assessed with standard coagulation testing and thromboelastography. Results: Three male patients were diagnosed with MIS-A at our centre from January to June 2022 with a median age of 55 years. All had tested positive for SARS-CoV-2 12–62 days prior to MIS-A presentation, with gastrointestinal and cardiovascular systems as the most commonly involved. Levels of IL-6, IL-10, IL-18, IP-10 and MCP-1 were raised whereas IL-1β, IFN-α, IFN-γ, IL-17 and TNF-α remained normal. Markedly elevated levels of C-reactive protein (CRP), ferritin and ICAM-1 were present in all. C5a was elevated in 2 patients. A hypercoagulable state was demonstrated by raised levels of D-dimer, factor VIII, von Willebrand factor antigen, and ristocetin cofactor with corresponding raised parameters in thromboelastography in the 2 patients who had their coagulation profile assessed. Conclusion: MIS-A patients demonstrate activation of pro-inflammatory cytokines, endotheliopathy, complement hyperactivation and hypercoagulability. Keywords: COVID-19, cytokines, hypercoagulability, hyperinflammatory syndrome

Vascular Function, Systemic Inflammation, and Coagulation Activation 18 Months after COVID-19 Infection: An Observational Cohort Study

INTRODUCTION

Among its effect on virtually all other organs, COVID-19 affects the cardiovascular system, potentially jeopardizing the cardiovascular health of millions. Previous research has shown no indication of macrovascular dysfunction as reflected by carotid artery reactivity, but has shown sustained microvascular dysfunction, systemic inflammation, and coagulation activation at 3 months after acute COVID-19. The long-term effects of COVID-19 on vascular function remain unknown.

MATERIALS AND METHODS

This cohort study involved 167 patients who participated in the COVAS trial. At 3 months and 18 months after acute COVID-19, macrovascular dysfunction was evaluated by measuring the carotid artery diameter in response to cold pressor testing. Additionally, plasma endothelin-1, von Willebrand factor, Interleukin(IL)-1ra, IL-6, IL-18, and coagulation factor complexes were measured using ELISA techniques.

RESULTS

The prevalence of macrovascular dysfunction did not differ between 3 months (14.5%) and 18 months (11.7%) after COVID-19 infection (p = 0.585). However, there was a significant decrease in absolute carotid artery diameter change, 3.5% ± 4.7 vs. 2.7% ± 2.5, p-0.001, respectively. Additionally, levels of vWF:Ag were persistently high in 80% of COVID-19 survivors, reflecting endothelial cell damage and possibly attenuated endothelial function. Furthermore, while levels of the inflammatory cytokines interleukin(IL)-1RA and IL-18 were normalized and evidence of contact pathway activation was no longer present, the concentrations of IL-6 and thrombin:antithrombin complexes were further increased at 18 months versus 3 months (2.5 pg/mL ± 2.6 vs. 4.0 pg/mL ± 4.6, p = 0.006 and 4.9 μg/L ± 4.4 vs. 18.2 μg/L ± 11.4, p < 0.001, respectively).

DISCUSSION

This study shows that 18 months after COVID-19 infection, the incidence of macrovascular dysfunction as defined by a constrictive response during carotid artery reactivity testing is not increased. Nonetheless, plasma biomarkers indicate sustained endothelial cell activation (vWF), systemic inflammation (IL-6), and extrinsic/common pathway coagulation activation (FVII:AT, TAT) 18 months after COVID-19 infection.

The impact of supervised physical exercise on chemokines and cytokines in recovered COVID-19 patients

COVID-19 is an infectious disease caused by the SARS-CoV-2 virus, which induces a high release of pro-inflammatory chemokines and cytokines, leading to severe systemic disorders. Further, evidence has shown that recovered COVID-19 patients still have some symptoms and disorders from COVID-19. Physical exercise can have many health benefits. It is known to be a potent regulator of the immune system, which includes frequency, intensity, duration, and supervised by a professional. Given the confinement and social isolation or hospitalization of COVID-19 patients, the population became sedentary or opted for physical exercise at home, assuming the guarantee of the beneficial effects of physical exercise and reducing exposure to SARS-CoV-2. This study aimed to investigate the effects of a supervised exercise protocol and a home-based unsupervised exercise protocol on chemokine and cytokine serum levels in recovered COVID-19 patients. This study was a prospective, parallel, two-arm clinical trial. Twenty-four patients who had moderate to severe COVID-19 concluded the intervention protocols of this study. Participants were submitted to either supervised exercise protocol at the Clinical Hospital of the Federal University of Pernambuco or home-based unsupervised exercise for 12 weeks. We analyzed serum levels of chemokines (CXCL8/IL-8, CCL5/RANTES, CXCL9/MIG, CCL2/MCP-1, and CXCL10/IP-10) and cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α, and IFN-γ). Before the interventions, no significant differences were observed in the serum levels of chemokines and cytokines between the supervised and home-based unsupervised exercise groups. The CXCL8/IL-8 (p = 0.04), CCL2/MCP-1 (p = 0.03), and IFN-γ (p = 0.004) levels decreased after 12 weeks of supervised exercise. In parallel, an increase in IL-2 (p = 0.02), IL-6 (p = 0.03), IL-4 (p = 0.006), and IL-10 (p = 0.04) was observed after the supervised protocol compared to pre-intervention levels. No significant differences in all the chemokines and cytokines were found after 12 weeks of the home-based unsupervised exercise protocol. Given the results, the present study observed that supervised exercise was able to modulate the immune response in individuals with post-COVID-19, suggesting that supervised exercise can mitigate the inflammatory process associated with COVID-19 and its disorders.

Clinical trial registration

https://ensaiosclinicos.gov.br/rg/RBR-7z3kxjk, identifier U1111-1272-4730.

Clinical trials on the pharmacological treatment of long COVID: A systematic review

The postacute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC), also known as post-acute coronavirus disease 19 (COVID-19) or the long COVID syndrome (long COVID) is an emerging public health concern. A substantial proportion of individuals may remain symptomatic months after initial recovery. An updated review of published and ongoing trials focusing on managing long COVID will help identify gaps and address the unmet needs of patients suffering from this potentially debilitating syndrome. A comprehensive literature search was conducted on the international databases and clinical trial registries from inception to 31 July 2022. This review included 6 published trials and 54 trial registration records. There is significant heterogeneity in the characterization of long COVID and ascertainment of primary outcomes. Most of the trials are focused on individual symptoms of long COVID or isolated organ dysfunction, classified according to cardiovascular, respiratory and functional capacity, neurological and psychological, fatigue, and olfactory dysfunction. Most of the interventions are related to the mechanisms causing the individual symptoms. Although the six published trials showed significant improvement in the symptoms or organ dysfunction studied, these initial studies lack internal and external validity limiting the generalizability. This review provides an update of the pharmacological agents that could be used to treat long COVID. Further standardization of the diagnostic criteria, inclusion of participants with concomitant chronic cardiometabolic diseases and standardization of outcomes will be essential in future clinical trials.

Inflammasome signaling proteins as biomarkers of COVID-19

Introduction

One of the main characteristics of COVID-19 is an exacerbated inflammatory response that results in cardiometabolic complications and dysfunction in the nervous system. Moreover, these complications may extend beyond the period of active SARS-CoV2 infection and even extend over a year. Thus, it is important to better understand the contribution of the inflammatory responses in COVID-19 patients, not just in the acute phase but also after the infection has subsided.

Methods

We measured the protein levels of inflammasome signaling proteins using Simple Plex microfluidics technology in patients with an active SARS-CoV2 infection and in recovered patients to determine their potential use as biomarkers of COVID-19. We carried out statistical analyses to identify which proteins were increased in COVID-19 patients with active infection and in recovered patients. The receiver operating characteristics (ROC) were calculated for each analyte to determine their potential fit as biomarkers.

Results

The inflammasome proteins caspase-1, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), interleukin (IL)-1β and IL-18 were elevated in the plasma of patients with active infection and remained elevated after the infection was resolved for approximately 2 months after. Levels of caspase-1 and ASC continued to increase long after patients had recovered from the infection. Furthermore, when measuring biomarkers of inflammation during active infection, analyses with area under the curve (AUC) values above 0.75 indicated that caspase-1, ASC, IL-1β and IL-18 are reliable biomarkers of the inflammatory response during active COVID-19 infection. Moreover, when measuring biomarkers of inflammation after recovery from active infection, caspase-1 and ASC presented AUC values above 0.9.

Discussion

These findings indicate that inflammasome signaling proteins can be used to reliably monitor the inflammatory innate immune response in COVID-19 patients.

Tripterin liposome relieves severe acute respiratory syndrome as a potent COVID-19 treatment

For coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), 15-30% of patients are likely to develop COVID-19-related acute respiratory distress syndrome (ARDS). There are still few effective and well-understood therapies available. Novel variants and short-lasting immunity are posing challenges to vaccine efficacy, so finding antiviral and antiinflammatory treatments remains crucial. Here, tripterin (TP), a traditional Chinese medicine, was encapsulated into liposome (TP lipo) to investigate its antiviral and antiinflammatory effects in severe COVID-19. By using two severe COVID-19 models in human ACE2-transgenic (hACE2) mice, an analysis of TP lipo's effects on pulmonary immune responses was conducted. Pulmonary pathological alterations and viral burden were reduced by TP lipo treatment. TP lipo inhibits SARS-CoV-2 replication and hyperinflammation in infected cells and mice, two crucial events in severe COVID-19 pathophysiology, it is a promising drug candidate to treat SARS-CoV-2-induced ARDS.

Clinical assessment of endothelial function in convalescent COVID-19 patients: a meta-analysis with meta-regressions

BACKGROUND

Endothelial dysfunction has been proposed to play a key role in the pathogenesis of coronavirus disease 2019 (COVID-19) and its post-acute sequelae. Flow-mediated dilation (FMD) is recognized as an accurate clinical method to assess endothelial function. Thus, we performed a meta-analysis of the studies evaluating FMD in convalescent COVID-19 patients and controls with no history of COVID-19.

METHODS

A systematic literature search was conducted in the main scientific databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Using the random effects method, differences between cases and controls were expressed as mean difference (MD) with 95% confidence intervals (95% CI). The protocol was registered on PROSPERO with reference number CRD42021289684.

RESULTS

Twelve studies were included in the final analysis. A total of 644 convalescent COVID-19 patients showed significantly lower FMD values as compared to 662 controls (MD: -2.31%; 95% CI: -3.19, -1.44; p < 0.0001). Similar results were obtained in the sensitivity analysis of the studies that involved participants in either group with no cardiovascular risk factors or history of coronary artery disease (MD: -1.73%; 95% CI: -3.04, -0.41; p = 0.010). Interestingly, when considering studies separately based on enrolment within or after 3 months of symptom onset, results were further confirmed in both short- (MD: -2.20%; 95% CI: -3.35, -1.05; p < 0.0001) and long-term follow-up (MD: -2.53%; 95% CI: -4.19, -0.86; p = 0.003). Meta-regression models showed that an increasing prevalence of post-acute sequelae of COVID-19 was linked to a higher difference in FMD between cases and controls (Z-score: -2.09; p = 0.037).

CONCLUSIONS

Impaired endothelial function can be documented in convalescent COVID-19 patients, especially when residual clinical manifestations persist. Targeting endothelial dysfunction through pharmacological and rehabilitation strategies may represent an attractive therapeutic option.Key messagesThe mechanisms underlying the post-acute sequelae of coronavirus disease 2019 (COVID-19) have not been fully elucidated.Impaired endothelial function can be documented in convalescent COVID-19 patients for up to 1 year after infection, especially when residual clinical manifestations persist.Targeting endothelial dysfunction may represent an attractive therapeutic option in the post-acute phase of COVID-19.

Pathophysiological mechanisms of thrombosis in acute and long COVID-19

COVID-19 patients have a high incidence of thrombosis, and thromboembolic complications are associated with severe COVID-19 and high mortality. COVID-19 disease is associated with a hyper-inflammatory response (cytokine storm) mediated by the immune system. However, the role of the inflammatory response in thrombosis remains incompletely understood. In this review, we investigate the crosstalk between inflammation and thrombosis in the context of COVID-19, focusing on the contributions of inflammation to the pathogenesis of thrombosis, and propose combined use of anti-inflammatory and anticoagulant therapeutics. Under inflammatory conditions, the interactions between neutrophils and platelets, platelet activation, monocyte tissue factor expression, microparticle release, and phosphatidylserine (PS) externalization as well as complement activation are collectively involved in immune-thrombosis. Inflammation results in the activation and apoptosis of blood cells, leading to microparticle release and PS externalization on blood cells and microparticles, which significantly enhances the catalytic efficiency of the tenase and prothrombinase complexes, and promotes thrombin-mediated fibrin generation and local blood clot formation. Given the risk of thrombosis in the COVID-19, the importance of antithrombotic therapies has been generally recognized, but certain deficiencies and treatment gaps in remain. Antiplatelet drugs are not in combination with anticoagulant treatments, thus fail to dampen platelet procoagulant activity. Current treatments also do not propose an optimal time for anticoagulation. The efficacy of anticoagulant treatments depends on the time of therapy initiation. The best time for antithrombotic therapy is as early as possible after diagnosis, ideally in the early stage of the disease. We also elaborate on the possible mechanisms of long COVID thromboembolic complications, including persistent inflammation, endothelial injury and dysfunction, and coagulation abnormalities. The above-mentioned contents provide therapeutic strategies for COVID-19 patients and further improve patient outcomes.

Post acute CoViD-19 syndrome (PACS) - Long CoViD

Patients sero-positive for the Systemic Acute Respiratory Syndrome Corona virus2 (SARS-CoV2) virus develop the Corona Virus Disease 2019 (CoViD-19). CoViD-19 may be asymptomatic in some individuals, proffer mild symptoms in other patients, and can be a serious and even lethal disease in a sub-group of the population. The variables that determine the severity of CoViD-19 have not been fully characterized. What is clear is that the patients who survive CoViD-19 return to a state of sero-negativity for SARS-CoV2 generally within 3-5 weeks. However, several cases of repeated infection have been reported, and a large proportion of CoViD-19-recovered patients manifest multi-system and multi-organ symptomatic pathologies several weeks-to-months after resuming sero-negativity for SARS-CoV2. This new pathological condition, originally termed Long Covid, is now recognized as the Post Acute CoViD-19 Syndrome (PACS). The original principal clusters of signs and symptoms of PACS: likelihood of relapse and reinfection, physical fatigue and cognitive slowdown, may actually be broadened to include immune deregulation, cardiovascular disease and coagulation abnormalities. The development and evaluation of new and improved clinical interventions for PACS are critical and timely.

Iron chelation of hetrombopag in aplastic anemia: a post hoc analysis of a phase II study

Hetrombopag is the only CFDA-approved thrombopoietin (TPO) receptor agonist for severe aplastic anemia (SAA) in China. Its chemical structure has an iron chelation domain. To explore the iron chelation effect of hetrombopag, we performed a post hoc analysis of the phase II clinical trial (NCT03557099). Thirty-five immunosuppressive therapy (IST)-refractory SAA patients were enrolled in the study, and the longitudinal changes of serum ferritin (SF) were assessed. At 18 weeks post-hetrombopag initiation, 51.4% of patients showed decreased SF levels by a median of 49.0 (18.1-95.5) % from baseline (median ΔSF decrease value, 917.2 ng/ml, range from 104.0 to 7030.0 ng/ml). A decrease in SF was found in 75.0% of hematologic responders and 31.6% of non-responders. Among the 24 patients with iron overload, 12 had decreased SF levels by up to 51% of the baseline. Patients with normal SF levels also showed decreased SF levels, and iron deficiency occurred in two patients. In conclusion, hetrombopag showed a powerful and rapid iron chelation effect.

Serial thrombin generation and exploration of alternative anticoagulants in critically ill COVID-19 patients: Observations from Maastricht Intensive Care COVID Cohort

Background

COVID-19 associated coagulopathy (CAC) is associated with an increase in thromboembolic events. Current guidelines recommend prophylactic heparins in the management of CAC. However, the efficacy of this strategy in the intensive care population remains uncertain.

Objective

We aimed to measure thrombin generation (TG) to assess CAC in intensive care unit (ICU) patients receiving thromboprophylaxis with low molecular weight heparin (LMWH) or unfractionated heparin (UFH). In addition, we performed statistical modeling to link TG parameters to patient characteristics and clinical parameters. Lastly, we studied the potency of different anticoagulants as an alternative to LMWH treatment in ex vivo COVID-19 plasma.

Patients/Methods

We included 33 patients with confirmed COVID-19 admitted at the ICU. TG was measured at least twice over the course of 6 weeks after admission. Thrombin generation parameters peak height and endogenous thrombin potential (ETP) were compared to healthy controls. Results were subsequently correlated with a patient characteristics and laboratory measurements. In vitro spiking in TG with rivaroxaban, dabigatran, argatroban and orgaran was performed and compared to LMWH.

Results

Anti-Xa levels of all patients remained within the therapeutic range throughout follow-up. At baseline, the mean (SE) endogenous thrombin potential (ETP) was 1,727 (170) nM min and 1,620 (460) nM min for ellagic acid (EA) and tissue factor (TF), respectively. In line with this we found a mean (SE) peak height of 353 (45) nM and 264 (96) nM for EA and TF. Although fluctuating across the weeks of follow-up, TG parameters remained elevated despite thromboprophylaxis. In vitro comparison of LMWHs and direct thrombin inhibitors (e.g., agratroban, dabigatran) revealed a higher efficacy in reducing coagulation potential for direct thrombin inhibition in both ellagic acid (EA) and tissue factor (TF) triggered TG.

Conclusion

In a sub-group of mechanically ventilated, critically ill COVID-19 patients, despite apparent adequate anti-coagulation doses evaluated by anti-Xa levels, thrombin generation potential remained high during ICU admission independent of age, sex, body mass index, APACHE II score, cardiovascular disease, and smoking status. These observations could, only partially, be explained by (anti)coagulation and thrombosis, inflammation, and multi-organ failure. Our in vitro data suggested that direct thrombin inhibition compared with LMWH might offer an alternate, more effective anticoagulant strategy in COVID-19.

Sustained VWF-ADAMTS-13 axis imbalance and endotheliopathy in long COVID syndrome is related to immune dysfunction

BACKGROUND

Prolonged recovery is common after acute SARS-CoV-2 infection; however, the pathophysiological mechanisms underpinning Long COVID syndrome remain unknown. VWF/ADAMTS-13 imbalance, dysregulated angiogenesis, and immunothrombosis are hallmarks of acute COVID-19. We hypothesized that VWF/ADAMTS-13 imbalance persists in convalescence together with endothelial cell (EC) activation and angiogenic disturbance. Additionally, we postulate that ongoing immune cell dysfunction may be linked to sustained EC and coagulation activation.

PATIENTS AND METHODS

Fifty patients were reviewed at a minimum of 6 weeks following acute COVID-19. ADAMTS-13, Weibel Palade Body (WPB) proteins, and angiogenesis-related proteins were assessed and clinical evaluation and immunophenotyping performed. Comparisons were made with healthy controls (n = 20) and acute COVID-19 patients (n = 36).

RESULTS

ADAMTS-13 levels were reduced (p = 0.009) and the VWF-ADAMTS-13 ratio was increased in convalescence (p = 0.0004). Levels of platelet factor 4 (PF4), a putative protector of VWF, were also elevated (p = 0.0001). A non-significant increase in WPB proteins Angiopoietin-2 (Ang-2) and Osteoprotegerin (OPG) was observed in convalescent patients and WPB markers correlated with EC parameters. Enhanced expression of 21 angiogenesis-related proteins was observed in convalescent COVID-19. Finally, immunophenotyping revealed significantly elevated intermediate monocytes and activated CD4+ and CD8+ T cells in convalescence, which correlated with thrombin generation and endotheliopathy markers, respectively.

CONCLUSION

Our data provide insights into sustained EC activation, dysregulated angiogenesis, and VWF/ADAMTS-13 axis imbalance in convalescent COVID-19. In keeping with the pivotal role of immunothrombosis in acute COVID-19, our findings support the hypothesis that abnormal T cell and monocyte populations may be important in the context of persistent EC activation and hemostatic dysfunction during convalescence.

Evolving outcomes of extracorporeal membrane oxygenation during the first 2 years of the COVID-19 pandemic: a systematic review and meta-analysis

Background

Extracorporeal membrane oxygenation (ECMO) has been used extensively for coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome (ARDS). Reports early in the pandemic suggested that mortality in patients with COVID-19 receiving ECMO was comparable to non-COVID-19-related ARDS. However, subsequent reports suggested that mortality appeared to be increasing over time. Therefore, we conducted an updated systematic review and meta-analysis, to characterise changes in mortality over time and elucidate risk factors for poor outcomes.

Methods

We conducted a meta-analysis (CRD42021271202), searching MEDLINE, Embase, Cochrane, and Scopus databases, from 1 December 2019 to 26 January 2022, for studies reporting on mortality among adults with COVID-19 receiving ECMO. We also captured hospital and intensive care unit lengths of stay, duration of mechanical ventilation and ECMO, as well as complications of ECMO. We conducted random-effects meta-analyses, assessed risk of bias of included studies using the Joanna Briggs Institute checklist and evaluated certainty of pooled estimates using GRADE methodology.

Results

Of 4522 citations, we included 52 studies comprising 18,211 patients in the meta-analysis. The pooled mortality rate among patients with COVID-19 requiring ECMO was 48.8% (95% confidence interval 44.8–52.9%, high certainty). Mortality was higher among studies which enrolled patients later in the pandemic as opposed to earlier (1st half 2020: 41.2%, 2nd half 2020: 46.4%, 1st half 2021: 62.0%, 2nd half 2021: 46.5%, interaction p value = 0.0014). Predictors of increased mortality included age, the time of final patient enrolment from 1 January 2020, and the proportion of patients receiving corticosteroids, and reduced duration of ECMO run.

Conclusions

The mortality rate for patients receiving ECMO for COVID-19-related ARDS has increased as the pandemic has progressed. The reasons for this are likely multifactorial; however, as outcomes for these patients evolve, the decision to initiate ECMO should include the best contextual estimate of mortality at the time of ECMO initiation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04011-2.