Background/Objectives: Although kidney transplant recipients (KTRs) who are immune-compromised have been shown to be at high risk of adverse acute COVID-19 outcomes (i.e., mortality and critical illness), the long-term outcomes of KTRs with a history of SARS-CoV-2 infection are unknown. We aimed to compare long-term outcomes of KTRs with and without exposure to SARS-CoV-2. Methods: This study retrospectively evaluated 1815 KTRs in the Montefiore Health System from 4 January 2001 to 31 January 2024. The final cohorts consisted of KTRs who survived COVID-19 (n = 510) and matched KTRs without COVID-19 (n = 510, controls). Outcomes were defined as all-cause mortality and changes in estimated glomerular filtration rate (eGFR) and urine protein to creatinine ratio (UPCR) from 30 days up to four years post index date. Kaplan-Meier survival analysis and Cox proportional modeling were performed for mortality. Generalized estimating equations were used to analyze changes in eGFR and UPCR across time. Results: There was no significant group difference in long-term all-cause mortality (adjusted hazard ratio = 0.66, [0.43, 1.01] p = 0.057). eGFR in controls and COVID-19 patients before infection similarly decreased -0.98 units/year [-1.50, -0.46]. By contrast, eGFR declined at a significantly greater rate (-1.80 units/year [-2.45, -1.15]) in KTRs after COVID-19 compared to KTRs without COVID-19. This association was only seen among male and not female KTRs. COVID-19 status was not significantly associated with rate of change in UPCR or acute kidney rejection rate. Conclusions: SARS-CoV-2 infection was associated with an accelerated decline in eGFR up to four years post infection, suggesting potential long-term implications for graft health. These findings underscore the importance of vigilant monitoring and management of kidney function post SARS-CoV-2 infection in this vulnerable population.

While the inhibitory receptor FcγRIIB has been shown to be upregulated on activated CD8+ T cells in both mice and humans, its effect on T cell fate during infection has not been fully elucidated. We identified an increase in FcγRIIB-expressing CD8+ T cells in patients with COVID-19 relative to healthy controls as well as in mouse models of viral infection. Despite its well-known role as an Fc receptor, FcγRIIB also ligates the immunosuppressive cytokine Fgl2, resulting in CD8+ T cell apoptosis. Both chronic LCMV infection in mice and COVID-19 in humans resulted in a significant increase in plasma Fgl2. Transfer of CD8+ T cells into a Fgl2-replete, but not Fgl2-devoid, environment resulted in elimination of FcγRIIB+, but not FcγRIIB-, CD8+ T cells. Similarly, plasma Fgl2 was directly proportional to CD8+ T cell lymphopenia in patients with COVID-19. RNA-Seq analysis demonstrated that Fgl2 was produced by murine virus-specific CD8+ T cells, with an increase in Fgl2 in CD8+ T cells elicited during chronic versus acute viral infection. Fgl2 was also upregulated in CD8+ T cells from patients with COVID-19 versus healthy controls. In summary, CD8+ T cell production of Fgl2 during viral infection underpinned an FcγRIIB-mediated loss of CD8+ T cell immunity in both mice and humans.

As the world grapples with the coronavirus-19 (COVID) pandemic, more reports are coming in regarding Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in endotheliopathy. It is a vascular condition in which endothelial cell injury or damage inflicts anatomical and functional changes in the endothelium, significantly impacting the physiological process and function. Previously, it was assumed that SARS-CoV-2 infects respiratory epithelial cells via spike glycoproteins present on the surface of the virus. However, severe cases and different autopsy studies described the clandestine role of this virus in infecting endothelial cells other than epithelial cells. It was observed that SARS-CoV-2 targets the pulmonary and extrapulmonary systems to damage the microvasculature and affect respiratory functioning, resulting in the onset of endotheliopathy, thrombosis, inflammation, pulmonary edema, and fibrosis. Such deleterious events are the consequence of the hyperactive immune response initiated by the SARS-CoV-2 infection, leading to pulmonary and extrapulmonary complications. However, the molecular mechanism behind endotheliopathy and other complications caused by this virus is elusive and will be unraveled by covering recent literature in this mini-review.

Glanzmann thrombasthenia (GT) is the most common inherited platelet disorder (IPD) with mucocutaneous bleeding and a failure of platelets to aggregate when stimulated. The molecular cause is insufficient or defective αIIbβ3, an integrin encoded by the ITGA2B and ITGB3 genes. On activation αIIbβ3 undergoes conformational changes and binds fibrinogen (Fg) and other proteins to join platelets in the aggregate. The application of next-generation sequencing (NGS) to patients with IPDs has accelerated genotyping for GT; progress accompanied by improved mutation curation. The evaluation by NGS of variants in other hemostasis and vascular genes is a major step toward understanding why bleeding varies so much between patients. The recently discovered role for glycoprotein VI in thrombus formation, through its binding to fibrin and surface-bound Fg, may offer a mechanosensitive back-up for αIIbβ3, especially at sites of inflammation. The setting up of national networks for IPDs and GT is improving patient care. Hematopoietic stem cell therapy provides a long-term cure for severe cases; however, prophylaxis by monoclonal antibodies designed to accelerate fibrin formation at injured sites in the vasculature is a promising development. Gene therapy using lentil-virus vectors remains a future option with CRISPR/Cas9 technologies offering a promising alternative route.

The 2019 coronavirus illness (COVID 2019) first manifests as a newly identified pneumonia and may quickly escalate to acute respiratory distress syndrome, which has caused a global pandemic. Except for individualized supportive care, no curative therapy has been steadfastly advised for COVID-19 up until this point. T cells and virus-specific T lymphocytes are required to guard against viral infection, particularly COVID-19. Delayed immunological reconstitution (IR) and cytokine storm (CS) continue to be significant barriers to COVID-19 cure. While severe COVID-19 patients who survived the disease had considerable lymphopenia and increased neutrophils, especially in the elderly, their T cell numbers gradually recovered. Exhausted T lymphocytes and elevated levels of pro-inflammatory cytokines, including IL6, IL10, IL2, and IL17, are observed in peripheral blood and the lungs. It implies that while convalescent plasma, IL-6 blocking, mesenchymal stem cells, and corticosteroids might decrease CS, Thymosin α1 and adaptive COVID-19-specific T cells could enhance IR. There is an urgent need for more clinical research in this area throughout the world to open the door to COVID-19 treatment in the future.

Compared to donations after brain death, donations after circulatory death present a series of difficulties: the acquisition of the family's consent, the need for qualified personnel and specific resources, death assessment, assessment of the organ, and graft care (pre- and post-transplant). These are all time-related factors that negatively impact the organ, resulting in increased tubular, glomerular, and vascular damage. The evaluation of the organ, as per today's standards, requires three hours for the preparation and processing of formalin-fixed paraffin-embedded (FFPE) samples. An alternative to this is the use of the extemporaneous frozen biopsy. However, frozen samples are considered a second choice in the decision-making process. This retrospective study investigates the reliability of the frozen samples in identifying a series of morphological alterations compared to the more accepted results from FFPE samples. Additionally, two important clinical data, terminal serum creatinine levels and warm ischemia time, were correlated to the presence of some morphological alterations in an attempt to find effective and fast strategies to predict the kidney transplant outcome.

In the intensive care unit (ICU), acute kidney injury (AKI) is the most common cause of morbidity and mortality. Hospital-acquired acute kidney injury (HAAKI) is AKI developing after 48 h. We aimed to study the development of AKI and its associated risk factors. We conducted a longitudinal observational study. Inclusion criteria were patients > 18 years of age admitted to ICU. The primary outcome was the development of AKI as defined by Kidney Disease Improving Global Outcomes (KDIGO) criteria. A total of 273 patients were included in the study. Out of 273, 44(16.11%) patients developed AKI. The mean age was 45.80(17.39) years, and 60.81% were males. The median acute physiology and chronic health evaluation (APACHE II) and sequential organ failure assessment (SOFA) scores were 12(8-18) and 5(3-7), respectively. Diabetes mellitus (23.44%) and hypertension (23.81%) were predominant comorbidities. The risk factors associated with AKI were serum chloride level, colistin, invasive ventilation, positive end-expiratory pressure (PEEP), and fluid balance. The hospital mortality was significantly higher in patients with AKI (43.18%) as compared with no AKI (14.41%). Among the secondary outcomes, 7 (15.90%) patients required renal replacement therapy (RRT) during hospitalisation. The length of ICU stay was higher in patients with AKI 8(5-13) compared to no AKI 5(3-8). A total of 16.11% developed HAAKI, and mortality was 43.18%. Post 6 months follow-up of AKI patients, mortality was 23%. Among survivors none of the patients were on RRT.Patients admitted with normal kidney function can develop AKI. Hence, careful monitoring of ICU patients is necessary.

COVID-19 pandemics increases venous thromboembolism (VTE) risk during hospitalization, despite prophylactic anticoagulation. Limited radiological diagnosis in pandemic requires a guided protocol for anticoagulant adjustment.

This retrospective cohort study was conducted at a single center as part of a quality improvement program evaluating the efficacy and safety of anticoagulation protocols. The study focused on implementing a guideline for anticoagulant dosing protocol based on dynamic changes in D-dimer levels in COVID-19 hospitalized patients. The dosing guideline allowed for dose escalation from standard prophylactic levels to escalated prophylactic or therapeutic levels, depending on the patient's risk profile for VTE. The primary endpoints included in-hospital survival comparing between fix and dynamic adjustment treatment groups. Secondary endpoints encompassed major and clinically relevant non-major bleeding (CRNMB) events, incidence of breakthrough thrombosis, length of hospitalization and ICU stay, days of mechanical ventilator use, and survival duration.

Among the 260 COVID-19-infected patients hospitalized between March 15th and June 15th, 2020. The patients received fixed anticoagulant dosage in 188, 72.3%) patients, while 72 (27.7%) were up-titrated according to the protocol. In-hospital survival at 30 days demonstrated superiority among patients whose anticoagulation was up-titrated to either escalated prophylactic or therapeutic (80.2%) compared to receiving fixed anticoagulant dosage (51.3%) (p=0.01). Bleeding events were significantly higher in up-titrate group (12.5%) compared to fixed anticoagulant dosage group (2.13%). Most of them are CRNMB.

A dynamic, D-dimer-based dose escalation of anticoagulation for hospitalized patients with COVID-19 holds promise in improving in-hospital mortality rates without a significant increase in fatal bleeding events.

Glenzocimab is a novel antithrombotic agent which targets platelet glycoprotein VI (GPVI) and does not induce haemorrhage. SARS-CoV-2 triggers a prothrombotic state and lung injury whose mechanisms include coagulopathy, endothelial dysfunction, and inflammation with dysregulated platelets.

GARDEN was a randomised double-blind, exploratory phase II study of glenzocimab in SARS-CoV-2 respiratory failure (NCT04659109). PCR+ adults in Brazil and France (7 centres) were randomized to standard-of-care (SOC) plus glenzocimab (1000 mg/dayx3 days) or placebo, followed for 40 days. Primary efficacy endpoint was clinical progression at Day 4. All analyses concerned the intention-to-treat population.

Between December 2020 and August 2021, 61 patients received at least one dose (30 glenzocimab vs 32 placebo) and 58 completed the study (29 vs 29). Clinical progression of COVID-19 ARDS was not statistically different between glenzocimab and placebo arms (43.3% and 29.0%, respectively; p = 0.245). Decrease in the NEWS-2 category at D4 was statistically significant (p = 0.0290) in the glenzocimab arm vs placebo. No Serious Adverse Event (SAE) was deemed related to study drug; bleeding related events were reported in 6 patients (7 events) and 4 patients (4 events) in glenzocimab and placebo arms, respectively.

Therapeutic GPVI inhibition assessment during COVID-19 was conducted in response to a Public Health emergency. Glenzocimab in coagulopathic patients under therapeutic heparin was neither associated with increased bleeding, nor SAE. Clinical impact of glenzocimab on COVID-19 ARDS was not demonstrated. A potential role for GPVI inhibition in other types of ARDS deserves further experimentation. Glenzocimab is currently studied in stroke (ACTISAVE: NCT05070260) and cardiovascular indications.

Coronavirus disease 2019 (COVID-19) triggers multiple components of the immune system and causes inflammation of endothelial walls across vascular beds, resulting in respiratory failure, arterial and venous thrombosis, myocardial injury, and multi-organ failure leading to death. Early in the COVID-19 pandemic, aspirin was suggested for the treatment of symptomatic individuals, given its analgesic, antipyretic, anti-inflammatory, anti-thrombotic, and antiviral effects. This study aimed to evaluate the association of aspirin use with various clinical outcomes in patients hospitalized for COVID-19.

This was a retrospective study involving patients aged ≥ 18 years and hospitalized for COVID-19 from March 2020 to October 2020. Primary outcomes were acute cardiovascular events (ST elevation myocardial infarction (STEMI), type 1 non-ST elevation myocardial infarction (NSTEMI), acute congestive heart failure (CHF), and acute stroke) and death. Secondary outcomes were respiratory failure, need for mechanical ventilation, and acute deep vein thrombosis (DVT)/pulmonary embolism (PE).

Of 376 patients hospitalized for COVID-19, 128 were taking aspirin. Significant proportions of native Americans were hospitalized for COVID-19 in both aspirin (22.7%) and non-aspirin (24.6%) groups. Between aspirin and non-aspirin groups, no significant differences were found with regard to mechanical ventilator support (21.1% vs. 15.3%, P = 0.16), acute cardiovascular events (7.8% vs. 5.2%, P = 0.32), acute DVT/PE (3.9% vs. 5.2%, P = 0.9), readmission rate (13.3% vs. 12.9%, P = 0.91) and mortality (23.4% vs. 20.2%, P = 0.5); however, the median duration of mechanical ventilation was significantly shorter (7 vs. 9 days, P = 0.04) and median length of hospitalization was significantly longer (5.5 vs. 4 days, P = 0.01) in aspirin group compared to non-aspirin group.

No significant differences were found in acute cardiovascular events, acute DVT/PE, mechanical ventilator support, and mortality rate between hospitalized COVID-19 patients who were taking aspirin compared to those not taking aspirin. However, larger studies are required to confirm our findings.

The role of platelets in coronavirus disease (COVID-19) severity requires further exploration. To determine whether the platelet index is useful in predicting COVID-19 severity, we compared the platelet index in patients with higher and lower oxygen requirements (≥ 4 L/min vs. < 4 L/min) and patients without COVID-19. We also analyzed the time course of the platelet index in each group. A total of 285 patients with COVID-19 and 36 without COVID-19 who were hospitalized at Fussa Hospital were analyzed. After matching for oxygen requirement at admission, multivariate analysis was performed. Platelets (≤ 16.6 × 104/μL) and platelet-large cell ratio (P-LCR) (≥ 27.8%) were significant factors influencing severity. Based on these factors, we created the Fussa platelet score, and the group with a Fussa platelet score ≥ 2 was significantly more likely to reach the 4 L/min oxygen requirement (event-free survival: Fussa platelet score ≥ 2 versus < 2, P < 0.00000001). Analysis of platelet index by time period showed a significant increase from 6-10 days after onset. The Fussa platelet score can be measured quickly, easily, and inexpensively in a clinic and may be useful in determining need for transfer to a critical care hospital.

The pathology of severe COVID-19 lung injury is predominantly diffuse alveolar damage, with other reported patterns including acute fibrinous organizing pneumonia, organizing pneumonia, and bronchiolitis. Lung injury was caused by primary viral injury, exaggerated immune responses, and superinfection with bacteria and fungi. Although fatality rates have decreased from the early phases of the pandemic, persistent pulmonary dysfunction occurs and its pathogenesis remains to be fully elucidated.

Background/Objectives: The hypercoagulable state associated with COVID-19 infection is associated with adverse outcomes and mortality. Studies have also demonstrated high rates of venous thromboembolism (VTE) events among patients with sepsis. We aimed to evaluate how the increase in thrombotic events in critically ill patients with COVID-19 infection compares to that of critically ill patients with non-COVID-19 sepsis. Methods: A chart review was performed of patients 18 years or older admitted to the intensive care unit (ICU) at Tampa General Hospital between 1 January 2020 and 31 December 2020 diagnosed with COVID-19 or sepsis secondary to other pathogens. Non-COVID-19 sepsis patients and COVID-19 patients were propensity-matched 3:1 on the Charlson Comorbidity Index. Multivariate analyses adjusting for confounding were conducted to report odds ratio (OR) and 95% confidence intervals (95% CIs) of predictors for thrombotic events and overall mortality. Results: After propensity score matching, 492 sepsis patients and 164 COVID-19 patients were included in the analysis. COVID-19 patients were significantly older (p = 0.021) and showed higher BMI (p < 0.001) than sepsis patients. COVID-19 patients did not show significantly higher odds of thrombosis after adjustment for confounders (OR 0.85, 95% CI 0.42-1.72), but had significantly lower odds of mortality than sepsis patients (OR 0.33, 95% CI 0.16-0.66). Conclusions: Our results suggest that further study is required to lower the rate of VTE in COVID-19 and non-COVID-19 sepsis patients admitted to the ICU; it is also reasonable to consider similar thromboembolism practices between these two patient groups.

Thromboembolic (TE) complications [myocardial infarction (MI), stroke, deep vein thrombosis (DVT), and pulmonary embolism (PE)] are common causes of mortality in hospitalised COVID-19 patients. Therefore, this review was undertaken to explore the incidence of TE complications and mortality associated with TE complications in hospitalised COVID-19 patients from different studies. A literature search was performed using ScienceDirect and PubMed databases using the MeSH term search strategy of "COVID-19", "thromboembolic complication", "venous thromboembolism", "arterial thromboembolism", "deep vein thrombosis", "pulmonary embolism", "myocardial infarction", "stroke", and "mortality". There were 33 studies included in this review. Studies have revealed that COVID-19 patients tend to develop venous thromboembolism (PE:1.0-40.0% and DVT:0.4-84%) compared to arterial thromboembolism (stroke:0.5-15.2% and MI:0.8-8.7%). Lastly, the all-cause mortality of COVID-19 patients ranged from 4.8 to 63%, whereas the incidence of mortality associated with TE complications was between 5% and 48%. A wide range of incidences of TE complications and mortality associated with TE complications can be seen among hospitalized COVID-19 patients. Therefore, every patient should be assessed for the risk of thromboembolic complications and provided with an appropriate thromboprophylaxis management plan tailored to their individual needs.

Despite the end of the pandemic, coronavirus disease 2019 (COVID-19) remains a major public health concern. The first waves of the virus led to a better understanding of its pathogenesis, highlighting the fact that there is a specific pulmonary vascular disorder. Indeed, COVID-19 may predispose patients to thrombotic disease in both venous and arterial circulation, and many cases of severe acute pulmonary embolism have been reported. The demonstrated presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within the endothelial cells suggests that direct viral effects, in addition to indirect effects of perivascular inflammation and coagulopathy, may contribute to pulmonary vasculopathy in COVID-19. In this review, we discuss the pathological mechanisms leading to pulmonary vascular damage during acute infection, which appear to be mainly related to thromboembolic events, an impaired coagulation cascade, micro- and macrovascular thrombosis, endotheliitis and hypoxic pulmonary vasoconstriction. As many patients develop post-COVID symptoms, including dyspnea, we also discuss the hypothesis of pulmonary vascular damage and pulmonary hypertension as a sequela of the infection, which may be involved in the pathophysiology of long COVID.

Platelets are one of the major targets of SARS-CoV-2. Activated platelets release prothrombotic substances, express adhesion molecules, and activate coagulation, thereby contributing to the thrombotic tendency in COVID-19. However, the antiplatelet therapy is not recommended in the current international guidelines. We think that the initiation timing and the target severity are the causes of the failure in clinical trials. As shown in the clinical studies that examined the effects of anticoagulants, early initiation in moderate severity is necessary for the success of antithrombotic therapy. Future trials are warranted to study the effects of antiplatelets in such conditions.

Thromboembolism is reported to be up to 27% in COVID-19 patients due to SARS-CoV-2 infection. Dysregulated systemic inflammation and various patient traits play a vital role in thrombosis progression.

To assess odds and associated factors for thrombosis development among Lebanese COVID-19 patients.

This was a case-control retrospective study conducted in January-May 2021. Patients infected with COVID-19 and developed thrombosis were classified as cases and patients who were thrombosis-free identified as control. A questionnaire assessed socio-demographics, clinical parameters, and WHO COVID-19 disease severity.

Among 267 patients, 26 (9.7%) developed thrombosis and the majority of thrombosis 34.6% was myocardial infarction, and the least (3.8%) was for catheter-related thrombosis. Results showed that the risk of thrombosis development is higher in patients with previous thromboembolic event (OR = 9.160) and previous intake of anti-hypertensive medications at home (OR = 3.116). However, females (OR = 0.330; CI: 0.118-0.925), intake of anticoagulants during hospital admission (OR = 0.126; CI: 0.053-0.300) and non-severe COVID-19 were at lower thrombosis risk (OR = 0.273). Patients who developed thromboembolic events had longer hospital stay (OR = 0.077).

Patients with COVID-19 and thromboembolism were at higher risk of mortality as compared to patients with COVID-19 but without thromboembolism. The use of anticoagulants significantly reduced the risk for thromboembolism.

One of the major pathomechanisms of COVID-19 is the interplay of hyperinflammation and disruptions in coagulation processes, involving thrombocytes. Antiplatelet therapy (AP) by anti-inflammatory effect and inhibition of platelet aggregation may affect these pathways. The aim of this study was to investigate if AP has an impact on the in-hospital course and medium-term outcomes in hospitalized COVID-19 patients. The study population (2170 COVID-19 patients: mean ± SD age 60 ± 19 years old, 50% male) was divided into a group of 274 patients receiving any AP prior to COVID-19 infection (AP group), and after propensity score matching, a group of 274 patients without previous AP (non-AP group). Patients from the AP group were less frequently hospitalized in the intensive care unit: 9% vs. 15%, 0.55 (0.33-0.94), developed less often shock: 9% vs. 15%, 0.56 (0.33-0.96), and required less aggressive forms of therapy. The AP group had more coronary revascularizations: 5% vs. 1%, 3.48 (2.19-5.55) and strokes/TIA: 5% vs. 1%, 3.63 (1.18-11.2). The bleeding rate was comparable: 7% vs. 7%, 1.06 (0.54-2.06). The patients from the AP group had lower 3-month mortality: 31% vs. 39%, 0.69 (0.51-0.93) and didn't differ significantly in 6-month mortality: 34% vs. 41%, 0.79 (0.60-1.04). When analyzing the subgroup with a history of myocardial infarction and/or coronary revascularization and/or previous stroke/transient ischemic attack and/or peripheral artery disease, AP had a beneficial effect on both 3-month: 37% vs. 56%, 0.58 (0.40-0.86) and 6-month mortality: 42% vs. 57%, 0.63 (0.44-0.92). Moreover, the favourable effect was highly noticeable in this subgroup where acetylsalicylic acid was continued during hospitalization with reduction of in-hospital: 19% vs. 43%, 0.31 (0.15-0.67), 3-month: 30% vs. 54%, 044 (0.26-0.75) and 6-month mortality: 33% vs. 54%, 0.49 (0.29-0.82) when confronted with the subgroup who had acetylsalicylic acid suspension during hospitalization. The AP may have a beneficial impact on hospital course and mortality in COVID-19 and shouldn't be discontinued, especially in high-risk patients.

Nonmuscle cell contractility is an essential feature underlying diverse cellular processes such as motility, morphogenesis, division and genome replication, intracellular transport, and secretion. Blood clot contraction is a well-studied process driven by contracting platelets. Megakaryocytes (MKs), which are the precursors to platelets, can be found in bone marrow and lungs. Although they express many of the same proteins and structures found in platelets, little is known about their ability to engage with extracellular proteins such as fibrin and contract. Here, we have measured the ability of MKs to compress plasma clots. Megakaryocytes derived from human induced pluripotent stem cells (iPSCs) were suspended in human platelet-free blood plasma and stimulated with thrombin. Using real-time macroscale optical tracking, confocal microscopy, and biomechanical measurements, we found that activated iPSC-derived MKs (iMKs) caused macroscopic volumetric clot shrinkage, as well as densification and stiffening of the fibrin network via fibrin-attached plasma membrane protrusions undergoing extension-retraction cycles that cause shortening and bending of fibrin fibers. Contraction induced by iMKs involved 2 kinetic phases with distinct rates and durations. It was suppressed by inhibitors of nonmuscle myosin IIA, actin polymerization, and integrin αIIbβ3-fibrin interactions, indicating that the molecular mechanisms of iMK contractility were similar or identical to those in activated platelets. Our findings provide new insights into MK biomechanics and suggest that iMKs can be used as a model system to study platelet contractility. Physiologically, the ability of MKs to contract plasma clots may play a role in the mechanical remodeling of intravascular blood clots and thrombi.

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

SARS-CoV-2 infection can result in ongoing, relapsing, or new symptoms or organ dysfunction after the acute phase of infection, termed Post-Acute Sequelae of SARS-CoV-2 (PASC), or long COVID. The characteristics, prevalence, trajectory and mechanisms of PASC are poorly understood. The objectives of the Researching COVID to Enhance Recovery (RECOVER) tissue pathology study (RECOVER-Pathology) are to: (1) characterize prevalence and types of organ injury/disease and pathology occurring with PASC; (2) characterize the association of pathologic findings with clinical and other characteristics; (3) define the pathophysiology and mechanisms of PASC, and possible mediation via viral persistence; and (4) establish a post-mortem tissue biobank and post-mortem brain imaging biorepository.

RECOVER-Pathology is a cross-sectional study of decedents dying at least 15 days following initial SARS-CoV-2 infection. Eligible decedents must meet WHO criteria for suspected, probable, or confirmed infection and must be aged 18 years or more at the time of death. Enrollment occurs at 7 sites in four U.S. states and Washington, DC. Comprehensive autopsies are conducted according to a standardized protocol within 24 hours of death; tissue samples are sent to the PASC Biorepository for later analyses. Data on clinical history are collected from the medical records and/or next of kin. The primary study outcomes include an array of pathologic features organized by organ system. Causal inference methods will be employed to investigate associations between risk factors and pathologic outcomes.

RECOVER-Pathology is the largest autopsy study addressing PASC among US adults. Results of this study are intended to elucidate mechanisms of organ injury and disease and enhance our understanding of the pathophysiology of PASC.

Coagulation disorders are described in COVID-19 and long COVID patients. In particular, SARS-CoV-2 infection in megakaryocytes, which are precursors of platelets involved in thrombotic events in COVID-19, long COVID and, in rare cases, in vaccinated individuals, requires further investigation, particularly with the emergence of new SARS-CoV-2 variants. CD147, involved in the regulation of inflammation and required to fight virus infection, can facilitate SARS-CoV-2 entry into megakaryocytes. MCT4, a co-binding protein of CD147 and a key player in the glycolytic metabolism, could also play a role in SARS-CoV-2 infection. Here, we investigated the susceptibility of megakaryocytes to SARS-CoV-2 infection via CD147 and MCT4. We performed infection of Dami cells and human CD34+ hematopoietic progenitor cells induced to megakaryocytic differentiation with SARS-CoV-2 pseudovirus in the presence of AC-73 and syrosingopine, respective inhibitors of CD147 and MCT4 and inducers of autophagy, a process essential in megakaryocyte differentiation. Both AC-73 and syrosingopine enhance autophagy during differentiation but only AC-73 enhances megakaryocytic maturation. Importantly, we found that AC-73 or syrosingopine significantly inhibits SARS-CoV-2 infection of megakaryocytes. Altogether, our data indicate AC-73 and syrosingopine as inhibitors of SARS-CoV-2 infection via CD147 and MCT4 that can be used to prevent SARS-CoV-2 binding and entry into megakaryocytes, which are precursors of platelets involved in COVID-19-associated coagulopathy.

Evidence increasingly shows that the risk of thrombotic complications in COVID-19 is associated with a hypercoagulable state. Several organizations have released guidelines for the management of COVID-19-related coagulopathy and prevention of VTE. However, an urgent need exists for practical guidance on the management of arterial thrombosis and thromboembolism in this setting.

What is the current available evidence informing the prevention and management of arterial thrombosis and thromboembolism in patients with COVID-19?

A group of approved panelists developed key clinical questions by using the Population, Intervention, Comparator, and Outcome (PICO) format that address urgent clinical questions regarding prevention and management of arterial thrombosis and thromboembolism in patients with COVID-19. Using MEDLINE via PubMed, a literature search was conducted and references were screened for inclusion. Data from included studies were summarized and reviewed by the panel. Consensus for the direction and strength of recommendations was achieved using a modified Delphi survey.

The review and analysis of the literature based on 11 PICO questions resulted in 11 recommendations. Overall, a low quality of evidence specific to the population with COVID-19 was found. Consequently, many of the recommendations were based on indirect evidence and prior guidelines in similar populations without COVID-19.

The existing evidence and panel consensus do not suggest a major departure from the management of arterial thrombosis according to recommendations predating the COVID-19 pandemic. Data on the optimal strategies for prevention and management of arterial thrombosis and thromboembolism in patients with COVID-19 are sparse. More high-quality evidence is needed to inform management strategies in these patients.

Treatment of coronavirus disease 2019 (COVID-19) patients may require antithrombotic and/or anti-inflammatory medications. We hypothesized that individualized anticoagulant (AC) management, based on diagnosis of coagulopathy using thromboelastography with platelet mapping (TEG-PM), would decrease the frequency of pulmonary failure (PF) requiring mechanical ventilation (MV), mitigate thrombotic and hemorrhagic events, and, in-turn, reduce mortality.

Hospital-admitted COVID-19 patients, age 18 or older, with escalating oxygen requirements were included. Prospective and supplemental retrospective chart reviews were conducted during a 2-month period. Patients were stratified into two groups based on clinician-administered AC treatment: TEG-PM guided vs. non-TEG guided.

Highly-elevated inflammatory markers (D-dimer, C-reactive protein, ferritin) were associated with poor prognosis but did not distinguish coagulopathic from noncoagulopathic patients. TEG-guided AC treatment was used in 145 patients vs. 227 treated without TEG-PM guidance. When managed by TEG-PM, patients had decreased frequency of PF requiring MV (45/145 [31%] vs. 152/227 [66.9%], P  < 0.0001), fewer thrombotic events (2[1.4%] vs. 39[17.2%], P  = 0.0019) and fewer hemorrhagic events (6[4.1%] vs. 24[10.7%], P  = 0.0240), and had markedly reduced mortality (43[29.7%] vs. 142[62.6%], P  < 0.0001). Platelet hyperactivity, indicating the need for antiplatelet medications, was identified in 75% of TEG-PM patients. When adjusted for confounders, empiric, indiscriminate AC treatment (not guided by TEG-PM) was shown to be an associated risk factor for PF requiring MV, while TEG-PM guided management was associated with a protective effect (odds ratio = 0.18, 95% confidence interval 0.08-0.4).

Following COVID-19 diagnosis, AC therapies based on diagnosis of coagulopathy using TEG-PM were associated with significantly less respiratory decompensation, fewer thrombotic and hemorrhagic complications, and improved likelihood of survival.

Consistent with well-established biochemical properties of coronaviruses, sialylated glycan attachments between SARS-CoV-2 spike protein (SP) and host cells are key to the virus's pathology. SARS-CoV-2 SP attaches to and aggregates red blood cells (RBCs), as shown in many pre-clinical and clinical studies, causing pulmonary and extrapulmonary microthrombi and hypoxia in severe COVID-19 patients. SARS-CoV-2 SP attachments to the heavily sialylated surfaces of platelets (which, like RBCs, have no ACE2) and endothelial cells (having minimal ACE2) compound this vascular damage. Notably, experimentally induced RBC aggregation in vivo causes the same key morbidities as for severe COVID-19, including microvascular occlusion, blood clots, hypoxia and myocarditis. Key risk factors for COVID-19 morbidity, including older age, diabetes and obesity, are all characterized by markedly increased propensity to RBC clumping. For mammalian species, the degree of clinical susceptibility to COVID-19 correlates to RBC aggregability with p = 0.033. Notably, of the five human betacoronaviruses, the two common cold strains express an enzyme that releases glycan attachments, while the deadly SARS, SARS-CoV-2 and MERS do not, although viral loads for COVID-19 and the two common cold infections are similar. These biochemical insights also explain the previously puzzling clinical efficacy of certain generics against COVID-19 and may support the development of future therapeutic strategies for COVID-19 and long COVID patients.

Sepsis, the foremost contributor to mortality in intensive care unit patients, arises from an uncontrolled systemic response to invading infections, resulting in extensive harm across multiple organs and systems. Recently, S100A8/A9 has emerged as a promising biomarker for sepsis and sepsis-induced organ injury, and targeting S100A8/A9 appeared to ameliorate inflammation-induced tissue damage and improve adverse outcomes. S100A8/A9, a calcium-binding heterodimer mainly found in neutrophils and monocytes, serves as a causative molecule with pro-inflammatory and immunosuppressive properties, which are vital in the pathogenesis of sepsis. Therefore, improving our comprehension of how S100A8/A9 acts as a pathological player in the development of sepsis is imperative for advancing research on sepsis. Our review is the first-to the best of our knowledge-to discuss the biology of S100A8/A9 and its release mechanisms, summarize recent advances concerning the vital roles of S100A8/A9 in sepsis and the consequential organ damage, and underscore its potential as a promising diagnostic biomarker and therapeutic target for sepsis.

Platelets contribute to COVID-19 clinical manifestations, of which microclotting in the pulmonary vasculature has been a prominent symptom. To investigate the potential diagnostic contributions of overall platelet morphology and their α-granules and mitochondria to the understanding of platelet hyperactivation and micro-clotting, we undertook a 3D ultrastructural approach. Because differences might be small, we used the high-contrast, high-resolution technique of focused ion beam scanning EM (FIB-SEM) and employed deep learning computational methods to evaluate nearly 600 individual platelets and 30 000 included organelles within three healthy controls and three severely ill COVID-19 patients. Statistical analysis reveals that the α-granule/mitochondrion-to-plateletvolume ratio is significantly greater in COVID-19 patient platelets indicating a denser packing of organelles, and a more compact platelet. The COVID-19 patient platelets were significantly smaller -by 35% in volume - with most of the difference in organelle packing density being due to decreased platelet size. There was little to no 3D ultrastructural evidence for differential activation of the platelets from COVID-19 patients. Though limited by sample size, our studies suggest that factors outside of the platelets themselves are likely responsible for COVID-19 complications. Our studies show how deep learning 3D methodology can become the gold standard for 3D ultrastructural studies of platelets.

Our study aimed to explore the association between serum C-reactive protein (CRP) and COVID-19 mortality. This is a retrospective cohort study of all patients admitted to 4 hospitals within the Montefiore Health System between March 1 and April 16, 2020, with SARS-CoV-2 infection. All-cause mortality were collected in 7 May 2020. The mortality risk was estimated using Cox proportional hazards models. Of the 3545 patients with a median age of 63.7 years, 918 (25.9%) died within the time of cohort data collection after admission. When the CRP was < 15.6 mg/L, the mortality rate increased with an adjusted HR of 1.57 (95% CI 1.30-1.91, P < 0.0001) for every 10 mg/L increment in the CRP. When the CRP was ≥ 15.6 mg/L, the mortality rate increased with an adjusted HR of 1.11 (95% CI 0.99-1.24, P = 0.0819) for every 10 mg/L increment in the CRP. For patients with COVID-19, the association between the CRP and the mortality risk was curve and had a saturation effect. When the CRP was small, the mortality rate increased significantly with the increase of CRP. When CRP > 15.6 mg/L, with the increase of CRP, the mortality rate increases relatively flat.

Single cell spatial interrogation of the immune-structural interactions in COVID -19 lungs is challenging, mainly because of the marked cellular infiltrate and architecturally distorted microstructure. To address this, we develop a suite of mathematical tools to search for statistically significant co-locations amongst immune and structural cells identified using 37-plex imaging mass cytometry. This unbiased method reveals a cellular map interleaved with an inflammatory network of immature neutrophils, cytotoxic CD8 T cells, megakaryocytes and monocytes co-located with regenerating alveolar progenitors and endothelium. Of note, a highly active cluster of immature neutrophils and CD8 T cells, is found spatially linked with alveolar progenitor cells, and temporally with the diffuse alveolar damage stage. These findings offer further insights into how immune cells interact in the lungs of severe COVID-19 disease. We provide our pipeline [Spatial Omics Oxford Pipeline (SpOOx)] and visual-analytical tool, Multi-Dimensional Viewer (MDV) software, as a resource for spatial analysis.

Ophthalmic manifestations and tissue tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported in association with coronavirus disease 2019 (COVID-19), but the pathology and cellular localization of SARS-CoV-2 are not well characterized. The objective of this study was to evaluate macroscopic and microscopic changes and investigate cellular localization of SARS-CoV-2 across ocular tissues at autopsy. Ocular tissues were obtained from 25 patients with COVID-19 at autopsy. SARS-CoV-2 nucleocapsid gene RNA was previously quantified by droplet digital PCR from one eye. Herein, contralateral eyes from 21 patients were fixed in formalin and subject to histopathologic examination. Sections of the droplet digital PCR-positive eyes from four other patients were evaluated by in situ hybridization to determine the cellular localization of SARS-CoV-2 spike gene RNA. Histopathologic abnormalities, including cytoid bodies, vascular changes, and retinal edema, with minimal or no inflammation in ocular tissues were observed in all 21 cases evaluated. In situ hybridization localized SARS-CoV-2 RNA to neuronal cells of the retinal inner and outer layers, ganglion cells, corneal epithelia, scleral fibroblasts, and oligodendrocytes of the optic nerve. In conclusion, a range of common histopathologic alterations were identified within ocular tissue, and SARS-CoV-2 RNA was localized to multiple cell types. Further studies will be required to determine whether the alterations observed were caused by SARS-CoV-2 infection, the host immune response, and/or preexisting comorbidities.

Megakaryocytes are commonly known as large, polyploid, bone marrow resident cells that contribute to hemostasis through the production of platelets. Soon after their discovery in the 19th century, megakaryocytes were described in tissue locations other than the bone marrow, specifically in the lungs and the blood circulation. However, the localization of megakaryocytes in the lungs and the contribution of lung megakaryocytes to the general platelet pool has only recently been appreciated. Moreover, the conception of megakaryocytes as uniform cells with the sole purpose of platelet production has been challenged. Here, we review the literature on megakaryocyte cell identity and location with a special focus on recent observations of megakaryocyte subpopulations identified by transcriptomic analyses.