Tag: platelets

Postural orthostatic tachycardia syndrome is associated with platelet storage pool deficiency

Abstract:

Mechanisms have been postulated to explain postural orthostatic tachycardia syndrome (POTS), however, the etiology of this often debilitating disorder remains unknown. We conducted a retrospective case-control study of 181 POTS patients who exhibited/reported bleeding symptoms for a specific platelet (PL) dysfunction disorder, delta granule storage pool deficiency (δ-SPD).Patients were included only if results of blood tests for δ-SPD were available.

Electron microscopy was utilized to diagnose δ-SPD. An ELISA assay was used to determine serotonin (5HT) concentration in PLs and medical record review was employed to collect patients’ clinical symptoms.The most common bleeding symptom was easy bruising (71%) but frequent nose bleeds, heavy menstrual bleeding, and a family history of bleeding were also commonly reported. Of the patients studied, 81% were diagnosed with δ-SPD.

Our investigation of 5HT concentration extracted from PLs revealed significantly lower levels of 5HT in POTS patients when compared to that of control subjects. Our data suggest that patients with POTS have significant comorbidities including bleeding symptoms and/or family bleeding histories, and have diminished PL 5HT levels supporting the hypothesis that POTS is a low 5HT level disorder.

While we describe a significant relationship with POTS and δ-SPD, this finding does not constitute an etiology for POTS.Our results establish an additional comorbidity frequently seen in POTS that could explain a number of disparate symptoms often affecting the severity of POTS.

Source: Gunning WT 3rd, Karabin BL, Blomquist TM, Grubb BP. Postural orthostatic tachycardia syndrome is associated with platelet storage pool deficiency. Medicine (Baltimore). 2016 Sep;95(37):e4849. doi: 10.1097/MD.0000000000004849. PMID: 27631244; PMCID: PMC5402587. https://pmc.ncbi.nlm.nih.gov/articles/PMC5402587/ (Full text)

Persistence of SARS-CoV-2 in Platelets and Megakaryocytes in Long COVID

Abstract:

Background: We have shown that acute COVID-19 pathophysiology is profoundly altered by infection of lung megakaryocytes (MKs) and platelets by SARS‑CoV‑2 (Zhu et al, 2022). A significant proportion of COVID-19 patients have symptoms persisting for > 3 months after initial infection with SARS-CoV-2, referred to as Long COVID or Post-acute Sequelae of SARS-CoV-2 (PASC) patients. Persistent or re-emerging symptoms are varied, with a predominance of asthenia, neuro-cognitive impairment and cardio-vascular symptoms. The pathophysiology underlying long-onset COVID remains poorly understood.

Methods: Blood was collected from patients with Long COVID with symptoms duration > 3 months (LC) (n=30), previously infected by SARS-CoV-2 but without persistent symptoms (resolved COVID-19 (CR), n=10), or healthy donor (n=20). MK frequency in blood was quantified by flow cytometry. Platelets and blood MKs were analysed for microclots, the presence of Spike protein and SARS-CoV-2 RNA by in situ hybridization and immunodetection visualized by confocal microscopy. Spike and serotonin were quantified in plasma.

Results: The frequency of CD41+ MKs in peripheral blood mononucleated cells (PBMCs) was significantly higher than healthy donors (0.28±0.05 versus 0.03±0.02) as a sign of MK infection, as we previously shown in acutely infected individuals with SARS-CoV-2 in platelets. Accordingly, in all samples analyzed, circulating MK in Long COVID sheltered both Spike and SARS-CoV-2 ssRNA, but also dsRNA suggestive of viral replication. These infected MKs produced blood platelets that contain also P Spike and SARS-CoV-2 ssRNA. Platelets microclots were detected in all tested Long COVID patients. Spike protein was detected at the pg level in 30 % of analyzed plasma from Long COVID but not CR individuals. The level of serotonin in platelet and of tryptophan hydroxylase-1 (TPH-1), the enzyme that regulates serotonin synthesis decreased significantly (p<0.0001) in blood of Long COVID patients compared to CR individuals.

Conclusions: In patients developing Long COVID, SARS-CoV-2 persists and replicates in MKs producing virus-containing platelets. The presence of spike in plasma might be an additional sign of viral persistence that could be used as a Long COVID biomarker. The presence of the virus could lead to abnormal platelet activation and the formation of microclots, which would contribute to the various symptoms and to deregulation of serotonin uptake, contributing to the neurocognitive symptoms observed in long-onset COVID.

Source: Feifan He, Boxin Huang, Andrea Cottignies-Calamarte, Wiem Bouchneb, Agathe Goubard, Faroudy Boufassa, Jacques Callebert, Dominique Salmon, Morgane Bomsel. Persistence of SARS-CoV-2 in Platelets and Megakaryocytes in Long COVID. The Conference on Retroviruses and Opportunistic Infections (CROI), March 3-6, 2024 | Denver, Colorado. https://www.croiconference.org/abstract/persistence-of-sars-cov-2-in-platelets-and-megakaryocytes-in-long-covid/ 

Long COVID-19 and Peripheral Serotonin: A Commentary and Reconsideration

Abstract:

We believe there are serious problems with a recently published and highly publicized paper entitled “Serotonin reduction in post-acute sequelae of viral infection.” The blood centrifugation procedure reportedly used by Wong et al would produce plasma that is substantially (over 95%) depleted of platelets. Given this, their published mean plasma serotonin values of 1.2 uM and 2.4 uM for the control/contrast groups appear to be at least 30 to 60 times too high and should be disregarded. The plasma serotonin values reported for the long COVID and viremia patients also should be disregarded, as should any comparisons to the control/contrast groups.

We also note that the plasma serotonin means for the two control/contrast groups are not in good agreement. In the “Discussion” section, Wong et al state that their results tend to support the use of selective serotonin reuptake inhibitors (SSRIs) for the treatment of COVID-19, and they encourage further clinical trials of SSRIs. While they state that, “Our animal models demonstrate that serotonin levels can be restored and memory impairment reversed by precursor supplementation or SSRI treatment”, it should be noted that no data are presented showing an increase or restoration in circulating serotonin with SSRI administration.

In fact, one would expect a marked decline in platelet serotonin due to SSRIs’ effective inhibition of the platelet serotonin transporter. Wong et al hypothesize that problems of long COVID arise from too little peripheral serotonin. However, given the frequent presence of a hyperaggregation state in long COVID, and the known augmenting effects of platelet serotonin on platelet aggregation, it is plausible to suggest that reductions in platelet serotonin might be associated with a lessening of the cardiovascular sequelae of COVID-19.

Source: Anderson GM, Cook EH, Blakely RD, Sutcliffe JS, Veenstra-VanderWeele J. Long COVID-19 and Peripheral Serotonin: A Commentary and Reconsideration. J Inflamm Res. 2024 Apr 11;17:2169-2172. doi: 10.2147/JIR.S456000. PMID: 38628604; PMCID: PMC11019386. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11019386/ (Full text)

Dysregulated platelet function in patients with postacute sequelae of COVID-19

Abstract:

Background: Postacute sequelae of COVID-19 (PASC), also referred to as “Long COVID”, sometimes follows COVID-19, a disease caused by SARS-CoV-2. Although SARS-CoV-2 is well known to promote a prothrombotic state, less is known about the thrombosis risk in PASC. Our objective was to evaluate platelet function and thrombotic potential in patients following recovery from SARS-CoV-2, but with clear symptoms of patients with PASC.

Methods: patients with PASC and matched healthy controls were enrolled in the study on average 15 months after documented SARS-CoV-2 infection. Platelet activation was evaluated by light transmission aggregometry (LTA) and flow cytometry in response to platelet surface receptor agonists. Thrombosis in platelet-deplete plasma was evaluated by Factor Xa activity. A microfluidics system assessed thrombosis in whole blood under shear stress conditions.

Results: A mild increase in platelet aggregation in patients with PASC through the thromboxane receptor was observed, and platelet activation through the glycoprotein VI (GPVI) receptor was decreased in patients with PASC compared to age- and sex-matched healthy controls. Thrombosis under shear conditions as well as Factor Xa activity were reduced in patients with PASC. Plasma from patients with PASC was an extremely potent activator of washed, healthy platelets – a phenomenon not observed when stimulating healthy platelets after incubation with plasma from healthy individuals.

Conclusions: patients with PASC show dysregulated responses in platelets and coagulation in plasma, likely caused by a circulating molecule that promotes thrombosis. A hitherto undescribed protective response appears to exist in patients with PASC to counterbalance ongoing thrombosis that is common to SARS-CoV-2 infection.

Source: Aggarwal A, Singh TK, Pham M, Godwin M, Chen R, McIntyre TM, Scalise A, Chung MK, Jennings C, Ali M, Park H, Englund K, Khorana AA, Svensson LG, Kapadia S, McCrae KR, Cameron SJ. Dysregulated platelet function in patients with postacute sequelae of COVID-19. Vasc Med. 2024 Feb 9:1358863X231224383. doi: 10.1177/1358863X231224383. Epub ahead of print. PMID: 38334067. https://pubmed.ncbi.nlm.nih.gov/38334067/

Persistent complement dysregulation with signs of thromboinflammation in active Long Covid

Abstract:

Long Covid is a debilitating condition of unknown etiology. We performed multimodal proteomics analyses of blood serum from COVID-19 patients followed up to 12 months after confirmed severe acute respiratory syndrome coronavirus 2 infection. Analysis of >6500 proteins in 268 longitudinal samples revealed dysregulated activation of the complement system, an innate immune protection and homeostasis mechanism, in individuals experiencing Long Covid.

Thus, active Long Covid was characterized by terminal complement system dysregulation and ongoing activation of the alternative and classical complement pathways, the latter associated with increased antibody titers against several herpesviruses possibly stimulating this pathway. Moreover, markers of hemolysis, tissue injury, platelet activation, and monocyte–platelet aggregates were increased in Long Covid. Machine learning confirmed complement and thromboinflammatory proteins as top biomarkers, warranting diagnostic and therapeutic interrogation of these systems.

Source: Carlo Cervia-Hasler et al. Persistent complement dysregulation with signs of thromboinflammation in active Long Covid. Science383,eadg7942(2024). DOI: 10.1126/science.adg7942 https://www.science.org/doi/10.1126/science.adg7942 (Full text)

Long COVID is primarily a Spike protein Induced Thrombotic Vasculitis

Abstract:

Long COVID describes an array of often debilitating symptoms in the aftermath of SARS-CoV-2 infection, with similar symptomatology affecting some people post-vaccination. With an estimated > 200 million Long COVID patients worldwide and cases still rising, the effects on quality of life and the economy are significant, thus warranting urgent attention to understand the pathophysiology. Herein we describe our perspective that Long COVID is a continuation of acute COVID-19 pathology, whereby coagulopathy is the main driver of disease and can cause or exacerbate other pathologies common in Long COVID, such as mast cell activation syndrome and dysautonomia.
Considering the SARS-CoV-2 spike protein can independently induce fibrinaloid microclots, platelet activation, and endotheliitis, we predict that persistent spike protein will be a key mechanism driving the continued coagulopathy in Long COVID. We discuss several treatment targets to address the coagulopathy, and predict that (particularly early) treatment with combination anticoagulant and antiplatelet drugs will bring significant relief to many patients, supported by a case study. To help focus attention on such treatment targets, we propose Long COVID should be referred to as Spike protein Induced Thrombotic Vasculitis (SITV). These ideas require urgent testing, especially as the world tries to co-exist with COVID-19.

Source: Kerr R, Carroll HA. Long COVID is primarily a Spike protein Induced Thrombotic Vasculitis. Research Square; 2023. DOI: 10.21203/rs.3.rs-2939263/v1. https://assets.researchsquare.com/files/rs-2939263/v1_covered_7190a867-1475-4b57-b220-716a953649f1.pdf?c=1684433225 (Full text)

Long COVID: pathophysiological factors and abnormalities of coagulation

Abstract:

Acute COVID-19 infection is followed by prolonged symptoms in approximately one in ten cases: known as Long COVID. The disease affects ~65 million individuals worldwide. Many pathophysiological processes appear to underlie Long COVID, including viral factors (persistence, reactivation, and bacteriophagic action of SARS CoV-2); host factors (chronic inflammation, metabolic and endocrine dysregulation, immune dysregulation, and autoimmunity); and downstream impacts (tissue damage from the initial infection, tissue hypoxia, host dysbiosis, and autonomic nervous system dysfunction).

These mechanisms culminate in the long-term persistence of the disorder characterized by a thrombotic endothelialitis, endothelial inflammation, hyperactivated platelets, and fibrinaloid microclots. These abnormalities of blood vessels and coagulation affect every organ system and represent a unifying pathway for the various symptoms of Long COVID.

Source: Turner S, Khan MA, Putrino D, Woodcock A, Kell DB, Pretorius E. Long COVID: pathophysiological factors and abnormalities of coagulation. Trends Endocrinol Metab. 2023 Jun;34(6):321-344. doi: 10.1016/j.tem.2023.03.002. Epub 2023 Apr 19. PMID: 37080828; PMCID: PMC10113134. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10113134/ (Full text)

Thrombo-inflammation in Long COVID – the elusive key to post-infection sequelae?

Abstract:

Long COVID is a public health emergency affecting millions of people worldwide, characterized by heterogenous symptoms across multiple organs systems. Here, we discuss the current evidence linking thrombo-inflammation to Post-acute sequelae of COVID-19 (PASC).

Studies have found persistence of vascular damage with increased circulating markers of endothelial dysfunction, coagulation abnormalities with increased thrombin generation capacity, and abnormalities in platelet counts in PASC. Neutrophil phenotype resembles acute COVID-19 with an increase in activation and NETosis. These insights are potentially linked by elevated platelet-neutrophil aggregate formation. This hypercoagulable state in turn can lead to microvascular thrombosis, evidenced by microclots and elevated D-Dimer in the circulation, as well as perfusion abnormalities in the lung and brain of Long COVID patients. Also, COVID-19 survivors suffer from an increased rate of arterial and venous thrombotic events.

We discuss three important, potentially intertwined hypotheses, that might contribute to thromboinflammation in Long COVID: Lasting structural changes, most prominently endothelial damage, caused during initial infection, a persistent viral reservoir, and immunopathology driven by a misguided immune system.

Lastly, we outline the necessity for large, well-characterized clinical cohorts and mechanistic studies to clarify the contribution of thromboinflammation to Long COVID.

Source: Nicolai L, Kaiser R, Stark K. Thrombo-inflammation in Long COVID – the elusive key to post-infection sequelae? J Thromb Haemost. 2023 May 11:S1538-7836(23)00400-2. doi: 10.1016/j.jtha.2023.04.039. Epub ahead of print. PMID: 37178769; PMCID: PMC10174338. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10174338/ (Full text)

NETosis induction reflects COVID-19 severity and Long COVID: insights from a two-center patient cohort study in Israel

Abstract:

Background: COVID-19 severity and its late complications continue to be poorly understood. Neutrophil extracellular traps (NETs) form in acute COVID-19, likely contributing to morbidity and mortality. This study evaluated immunothrombosis markers in a comprehensive cohort of acute and recovered COVID-19 patients, including the association of NETs with LongCOVID.

Methods: One-hundred-seventy-seven patients were recruited from clinical cohorts at two Israeli centers: acute COVID-19 (mild/moderate, severe/critical), convalescent COVID-19 (recovered and Long COVID), along with 54 non-COVID controls. Plasma was examined for markers of platelet activation, coagulation, and NETs. Ex vivo NETosis induction capability was evaluated after neutrophil incubation with patient plasma.

Results: Soluble P-selectin, Factor VIII, von Willebrand factor, and platelet factor 4 were significantly elevated in COVID-19 patients versus controls. Myeloperoxidase (MPO)-DNA complex levels were increased only in severe COVID-19 and did not differentiate between COVID-19 severities or correlate with thrombotic markers. NETosis induction levels strongly correlated with illness severity/duration, platelet activation markers, and coagulation factors, and were significantly reduced upon dexamethasone treatment and recovery. Long COVID patients maintained higher NETosis induction, but not NET fragments, compared to recovered convalescent patients.

Conclusions: Increased NETosis induction can be detected in Long COVID patients. NETosis induction appears to be a more sensitive NET measurement than MPO-DNA levels in COVID-19, differentiating between disease severity and Long COVID patients. Ongoing NETosis induction capability in Long COVID may provide insights into pathogenesis and serve as a surrogate marker for persistent pathology. This study emphasizes the need to explore neutrophil-targeted therapies in acute and chronic COVID-19.

Source: Krinsky N, Sizikov S, Nissim S, Dror A, Sas A, Prinz H, Pri-Or E, Perek S, Raz-Pasteur A, Lejbkowicz I, Cohen-Matsliah SI, Almog R, Chen N, Kurd R, Jarjou’i A, Rokach A, Ben-Chetrit E, Schroeder A, Caulin AF, Yost CC, Schiffman JD, Goldfeder M, Martinod K. NETosis induction reflects COVID-19 severity and Long COVID: insights from a two-center patient cohort study in Israel. J Thromb Haemost. 2023 Apr 11:S1538-7836(23)00274-X. doi: 10.1016/j.jtha.2023.02.033. Epub ahead of print. PMID: 37054916; PMCID: PMC10088279. https://www.jthjournal.org/article/S1538-7836(23)00274-X/fulltext (Full text available as PDF file)

Long COVID: pathophysiological factors and abnormalities of coagulation

Abstract:

Acute COVID-19 infection is followed by prolonged symptoms in approximately one in ten cases: known as Long COVID. The disease affects ~65 million individuals worldwide. Many pathophysiological processes appear to underlie Long COVID, including viral factors (persistence, reactivation, and bacteriophagic action of SARS CoV-2); host factors (chronic inflammation, metabolic and endocrine dysregulation, immune dysregulation, and autoimmunity); and downstream impacts (tissue damage from the initial infection, tissue hypoxia, host dysbiosis, and autonomic nervous system dysfunction). These mechanisms culminate in the long-term persistence of the disorder characterized by a thrombotic endothelialitis, endothelial inflammation, hyperactivated platelets, and fibrinaloid microclots. These abnormalities of blood vessels and coagulation affect every organ system and represent a unifying pathway for the various symptoms of Long COVID.

Source: Simone Turner, Asad Khan, David Putrino, Ashley Woodcock, Douglas B. Kell, and Etheresia Pretorius.  Long COVID: pathophysiological factors and abnormalities of coagulation. Trends in Endocrinology & Metabolism. April 19, 2023. https://www.sciencedirect.com/science/article/pii/S1043276023000553 (Full text)