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ASAIO Journal ; 68:61-62, 2022.
Article in English | EMBASE | ID: covidwho-2032179


Background: Patients with severe COVID-19 related respiratory failure may require veno-venous extracorporeal membrane oxygenation (VV ECMO). After decannulation, patients on VV ECMO have historically had high percentages of cannula-associated deep vein thrombosis (CaDVT). Due to their hypercoagulable state and prolonged course on VV ECMO, we hypothesized that patients with COVID-19 would experience a higher rate of CaDVT when compared to their non-COVID-19 counterparts. We also described the association between location and size of cannula in the development of CaDVTs. Methods: This was a single center retrospective review of patients ≥ 18 years old who were treated with VV ECMO and decannulated from January 1, 2014, to January 10, 2022. Patients who were placed on VV ECMO due to trauma and patients who were cannulated for veno-arterial ECMO were excluded. Patients were managed in a dedicated Lung Rescue Unit and anticoagulated with a heparin infusion at a goal partial thromboplastin time (aPTT) of 45-55 or 60-80 depending on the presence of clotting complications. Post-decannulation venous duplexes were performed 24 hours after decannulation and if positive for DVT, performed again in 2 weeks. Univariate and multivariate analyses were conducted to analyze our primary outcome of the development of CaDVT. Results: A total of 291 patients met our inclusion criteria: 76 COVID-19 VV ECMO patients and 215 non-COVID-19 VV ECMO patients. Decannulated COVID-19 VV ECMO patients had a significantly higher body mass index (BMI) (35.8, 32.9, p= 0.03) and length of ECMO run (hours) (660, 312, p< 0.001) than their non-COVID-19 counterparts. Most decannulated patients in both groups received post-decannulation duplexes (96%, 99%, p= 0.45). COVID-19 and non-COVID-19 patients decannulated from VV ECMO both experienced high incidences of CaDVT on initial post-decannulation ultrasound (95%, 88%, p= 0.13). COVID-19 patients were more likely to have multiple CaDVTs (32%, 11%, p< 0.001). Patients with COVID- 19 experienced a higher rate of right common femoral CaDVT (47%, 17%, p< 0.001) and a higher percentage of 25 French drainage cannula CaDVT (48%, 18%, p< 0.001). COVID-19 VV ECMO patients had a significantly higher incidence of persistent CaDVT on repeat ultrasound (78%, 56%, p= 0.03). A logistic regression was performed with all decannulated patients. Age, BMI, hours on ECMO, COVID-19 status, and size and location of ECMO cannulas did not predict the presence of DVT. Conclusion: Both COVID-19 and non-COVID-19 VV ECMO patients had high rates of CaDVTs. The utilization of VV ECMO in COVID-19 respiratory failure was associated with a higher incidence of CaDVTs on repeat ultrasound as compared to patients with non-COVID-19 related respiratory failure. Regular post-decannulation screening, treatment, and follow up imaging should be performed. Further investigation into the effect of anticoagulation strategy is needed. (Table Presented).

Topics in Antiviral Medicine ; 30(1 SUPPL):120, 2022.
Article in English | EMBASE | ID: covidwho-1880030


Background: T cells have been shown to play a role in the immune response to SARS-CoV-2. Identification of T cell epitopes and a better understanding of the T cell repertoire will provide important insights into how T cells impact antiviral immunity. Here, we identified T cell epitopes within the Spike (S), Nucleocapsid (N) and Membrane (M) proteins from SARS-CoV-2 convalescent individuals and performed TCR sequencing on epitope-specific T cells. Methods: Epitope mapping was performed by IFNγ ELISpot on PBMC from SARS-CoV-2 convalescent patients with mild/moderate disease (n = 19 for S;n=15 for N and M), and minimum epitopes were determined using truncated peptides and ICS. TCR sequence analysis was performed on a subset of individuals (n=9 donors;2-3 epitopes/donor), with longitudinal samples for 7 donors (2-3 time points/donor;33 to 236 days post-symptom onset). T cells were stimulated with individual peptides for 6 hours and sorted based on the expression of activation markers (CD4+: CD69, CD40L;CD8+: CD69, CD107a, surface TNF). scRNAseq was performed on sorted cells for TCR repertoire and transcriptome analysis. Results: We identified several peptides recognized by multiple individuals, including S42 (amino acids 165-179;7/19 donors), S302 (a.a. 1205-1219;6/19 donors), N27 (a.a. 106-120;6/14 donors) and M45 (a.a. 177-191;10/14 donors). S42 elicited both CD4+ (n=5) and CD8+ (n=1) T cell responses, with one individual having both a CD4+ and CD8+ response. The minimum epitope for S42 was determined to be a 9mer (FEYVSQPFL) for both CD4+ and CD8+ cells. TCR sequencing of S42-specific T cells identified a dominant gene pairing for TCRα across multiple donors (TRAV35;TRAJ42) and for both CD4+ and CD8+ T cells (Figure 1). In general, epitope-specific CD4+ responses (S42, M45) were more clonally diverse than CD8+ responses (S42, S302, N27). For both CD4+ and CD8+ T cells, conserved TCR gene usage and gene pairings could be identified within multiple donors responding to the same epitope. Conclusion: These data suggest that in SARS-CoV-2 convalescent people, epitope-specific CD4+ and CD8+ T cells can differ in their clonal diversity and that related TCRs can be identified across multiple donors. S42-specific T cell studies are ongoing to determine their transcriptional profile and pMHC presentation. Ongoing longitudinal analysis will provide a better understanding of different epitope-specific TCR repertoires and T cell transcriptional profiles, and how they evolve after infection.

Anaesthesia ; 76:28-28, 2021.
Article in English | Web of Science | ID: covidwho-1312047
Topics in Antiviral Medicine ; 29(1):31, 2021.
Article in English | EMBASE | ID: covidwho-1249971


Background: The role that CD4+ and CD8+ T cells play in the protection from and disease severity of COVID-19 is not completely understood. A better understanding of T cell function and the epitopes that they target will be invaluable in the development of the next generation of vaccines and therapeutics. To better understand the role of T cells, we characterized the frequency, effector functions and phenotype of SARS-CoV-2-specific CD4+ and CD8+ T cells in a cohort of patients who recovered from COVID-19, and identified multiple peptides that contain T cell epitopes within the Spike protein (S), Nucleocapsid protein (N) and Membrane protein (M). Methods: The frequency and phenotype of SARS-CoV-2-specific T cells from convalescent patients with mild or moderate disease (n=27, 25 to 92 days post-symptom onset) were determined by polychromatic flow cytometry and intracellular cytokine staining (ICS). Cells were stimulated for 6 hours with peptide pools corresponding to S, N and M. Cytokine production, memory phenotype, chemokine receptor expression and PD-1 expression were analyzed. For a subset of individuals (n = 19 for S;n=14 for N and M), IFNg ELISpot assays and peptide matrices were utilized to identify peptides that contain T cell epitopes. Results: CD4+ T cell responses to S, N and/or M were detected in almost all donors by ICS and were predominantly a Th1-type response as determined by cytokine production (IFNg, IL-2 or TNF) and expression of CXCR3. A majority of the antigen-specific CD4+ cells were found in the effector memory compartment. Although less robust than the CD4+ T cell response, antigenspecific CD8+ T cells were detected in a majority of donors, were found within the effector memory compartments and displayed modest PD-1 upregulation. Multiple peptides that contain T cell epitopes were identified by IFNg ELISpot (Figure 1). Some of the most commonly identified peptides include S42 (amino acids 165-179;7/19 donors), S205 (a.a. 817-831;10/19 donors), N83 (a.a. 329-343;7/14 donors), M37 (a.a. 145-159;8/14 donors) and M45 (a.a. 177-191;10/14 donors). Conclusion: These data suggest that T cells that target S, N and M play an important role in the immune response to SARS-CoV-2 and should be considered in future vaccine development. Further studies such as transcriptomic analysis and the TCR usage in longitudinal samples will provide a better understanding of epitope-specific T cells and their longevity.