ABSTRACT
Background: T cells play an essential role in SARS-CoV-2 immunity, including in defense against severe COVID-19. However, most studies analyzing SARSCoV- 2-specific T cells have been limited to analysis of blood. Furthermore, the role of T cells in SARS-CoV-2 immunity in pregnant women, which are at disproportionately higher risk of severe COVID-19, is poorly understood. Method(s): Here, we quantitated and deeply phenotyped SARS-CoV-2-specific T cells from convalescent women (n=12) that had mild (non-hospitalized) COVID-19 during pregnancy. Endometrial, maternal blood, and fetal cord blood specimens were procured at term, which ranged from 3 days to 5 months post-infection. SARS-CoV-2-specific T cells were deeply analyzed by CyTOF using a tailored phenotyping panel designed to assess the effector functions, differentiation states, and homing properties of the cells. Result(s): SARS-CoV-2-specific T cells were more abundant in the endometrium than in maternal or fetal cord blood. In a particularly striking example, in one donor sampled 5 months after infection, SARS-CoV-2-specific CD8+ T cells comprised 4.8% of total endometrial CD8+ T cells, while it only reached 1.4% in blood. Endometrial SARS-CoV-2-specific T cells were more frequently of the memory phenotype relative to their counterparts in maternal and fetal cord blood, which harbored higher frequencies of naive T cells. Relative to their counterparts in blood, endometrial SARS-CoV-2-specific T cells exhibited unique phenotypic features, including preferential expression of the T resident memory marker CD69, inflammatory tissue-homing receptor CXCR4, and the activation marker 4-1BB. Endometrial T cells were highly polyfunctional, and could secrete IFNg, TNFa, MIP1b, IL2, and/or IL4 in response to spike peptide stimulation. By contrast, their counterparts in blood preferentially produced the cytolytic effectors perforin and granzyme B. Conclusion(s): Polyfunctional SARS-CoV-2-specific T cells primed by prior exposure to the virus are abundant and persist in endometrial tissue for months after infection. These cells exhibit unique phenotypic features including preferential expression of select chemokine receptors and activation molecules. Compared to their blood counterparts, the effector functions of these cells are more cytokine-driven and less cytolytic. The long-term persistence of these cells in the endometrium may help protect future pregnancies from SARS-CoV-2 re-infection.
ABSTRACT
Background: A significant portion of individuals experience persistent symptoms months after SARS-CoV-2 infection, broadly referred to as Long COVID (LC). Although the frequencies of subsets of SARS-CoV-2-specific T cells have been shown to differ in individuals with LC relative to those with complete recovery, a deep dive into phenotypic and functional features of total and SARSCoV- 2-specific T cells from individuals with LC has yet to be performed. Method(s): Here, we used CyTOF to characterize the phenotypes and effector functions of T cells from LIINC cohort. The median age was 46, the cohort was 55.8% female, and 9/43 had been hospitalized. Participants were reported a median of 7 LC symptoms at 8 months. SARS-CoV-2-specific total antibody levels were also measured in concurrent sera. Manual gating was used to define T cell subsets, SPICE analyses for polyfunctionality, T cell clustering for phenotypic features, and linear regression for correlation. Permutation tests, Student's t tests, and Welch's t test were used for statistical analysis. Result(s): SARS-CoV-2 total antibody responses were elevated in the LC group (p=0.043), and correlated with frequencies of SARS-CoV-2-specific T cells in those without LC (r=0.776, p< 0.001) but not those with LC. While the frequencies of total SARS-CoV-2-specific CD4+ and CD8+ T cells were similar between individuals with and without LC, those from individuals without LC tended to be more polyfunctional (co-expressing IFNgamma, TNFalpha, IL2, and/or MIP1beta). CD4+ T cells from individuals with LC harbored higher frequencies of Tcm (p=0.003), Tfh (p=0.037), and Treg subsets (p=0.0412), and preferentially expressed a variety of tissue homing receptors including CXCR4 and CXCR5 (p=0.037). SARS-CoV-2-specific CD4+ T cells producing IL6, albeit rare, were observed exclusively among those with LC (p=0.016). In addition, participants with LC harbored significantly higher frequencies of SARS-CoV-2-specific CD8+ T cells co-expressing exhaustion markers PD1 and CTLA4 (p=0.018). Conclusion(s): Long COVID is characterized by global phenotypic differences in the CD4+ T cell compartment in ways suggesting preferential migration of these cells to inflamed mucosal tissues. Individuals with LC also harbor higher numbers of exhausted SARS-CoV-2-specific CD8+ T cells, potentially implicating viral persistence. Finally, our data additionally suggest that individuals with LC may uniquely exhibit an uncoordinated T cell and antibody response during COVID-19 convalescence.
ABSTRACT
Collection of peripheral blood stem cells (PBSCs) for autologous stem cell transplant (ASCT) requires mobilization from the bone marrow. There is variation in mobilization choice;during the COVID-19 pandemic BSBMT&CT guidelines recommended using granulocyte-colony stimulating factor (G-CSF) alone to minimize the use of chemotherapy. We report on the impact of mobilization regimen on stem cell collection, and whether IMiD-containing induction therapy impacts on mobilization and consequently transplant engraftment times for 83 patients undergoing ASCT at Leeds Teaching Hospitals. Cyclophosphamide plus G-CSF (cyclo-G) mobilization yielded more CD34+ cells (8.94 vs. 4.88 x106/kg, p = < 0.0001) over fewer days (1.6 vs. 2.4 days, p = 0.007), and required fewer doses of salvage Plerixafor than G-CSF only (13.6% vs. 35%, p = 0.0407). IMiD-containing induction impaired all of these factors. CD34+ doses > 8x106/kg were more frequent with Cyclo-G (62% vs. 11%, p = 0.0001), including for those receiving IMiD 1st line induction (50% vs. 13.3%, p = 0.0381). Note that 92.6% of those receiving IMiD-free inductions were mobilized with Cyclo-G. The novel agents used in modern induction regimens (e.g Daratumumab) have been shown to impair yields, increasing the importance of optimizing mobilization regimens in the first instance. Furthermore, as cellular therapies become established in the management of multiple myeloma emerging data highlights the potential benefits of stem cell top up in the management of the haematological toxicities of these therapies. Our findings support re-adoption of Cyclo-G as the gold standard for mobilization to optimize PBSC harvesting and ensure sufficient cells for subsequent ASCTs.Copyright © 2023 The Authors. eJHaem published by British Society for Haematology and John Wiley & Sons Ltd.
ABSTRACT
Genome-wide association studies have recently identified 3p21.31, with lead variant pointing to the CXCR6 gene, as the strongest thus far reported susceptibility risk locus for severe manifestation of COVID-19. In order the determine its role, we measured plasma levels of Chemokine (CXC motif) ligand 16 (CXCL16) in the plasma of COVID-19 hospitalized patients. CXCL16 interacts with CXCR6 promoting chemotaxis or cell adhesion. The CXCR6/CXCL16 axis mediates homing of T cells to the lungs in disease and hyper-expression is associated with localized cellular injury. To characterize the CXCR6/CXCL16 axis in the pathogenesis of severe COVID-19, plasma concentrations of CXCL16 collected at baseline from 115 hospitalized COVID-19 patients participating in ODYSSEY COVID-19 clinical trial were assessed together with a set of controls. We report elevated levels of CXCL16 in a cohort of COVID-19 hospitalized patients. Specifically, we report significant elevation of CXCL16 plasma levels in association with severity of COVID-19 (as defined by WHO scale) (P-value<0.02). We replicate this finding in an independent replication set CALYPSO (P-value<0.0012). We also observe a highly significant effect on mortality (P-value<0.0004) in association with higher CXCL16 plasma levels. We are further characterizing the expression of CXCR6 in in CD8+ T cells. Our current study is the largest thus far study reporting CXCL16 levels in COVID-19 hospitalized patients (with whole-genome sequencing data available). Latest results support the significant role of the CXCR6/CXCL16 axis in the immunopathogenesis of severe COVID-19 and warrants further studies to understand which patients would benefit most from targeted treatments.
ABSTRACT
Background: The number of cases of SARS-CoV-2 infection after BNT162b2 mRNA vaccination is significantly higher in elderly people, which has been associated to lower frequencies of SARS-CoV-2 neutralizing antibodies. Our objective was to investigate the differences in the cellular response in old and young people after the SARS-CoV-2 vaccination. Methods: Young (24-53 years, n=20) and old (70-76 years, n=20) healthy subjects vaccinated with BNT162b2 SARS-CoV-2 mRNA vaccine were studied before vaccination, two weeks after the first dose and two months after the second dose. SARS-CoV-2 (spike) specific T cell response, TLR-4 dependent monocyte response and TLR-3 dependent myeloid dendritic cell (DC) response and DC, monocyte and T-cell immunophenotype, were studied by multiparametric flow cytometry. TLR-9 dependent interferon-α (IFNα) production by PBMCs was measured by ELISA and thymic function assayed by sj/β TREC ratio using droplet digital PCR. Results: The SARS-CoV-2 specific T cell response was lower and less polyfunctional in old people. Most of the differences in CD4+ and CD8+ T cell subsets were found in degranulation (CD107a), cytokine (IFN-γ) and cytotoxic (perforin) profile (eg, Memory CD8+ perforin+;p=0.0016). The lower SARS-CoV-2 specific T cell response was associated with lower thymic function levels (eg, Memory CD4+ perforin+, r=0.631;p=0.0001). The vaccination induced a higher activation and proliferation (eg, CM CD4 HLA-DR+ p=0.002, Ki67+ p=0.019) of T cells in young people than in old ones, in addition to a higher level of homing makers to different tissues and inflammatory sites (eg, CD1c mDC integrin β7+ p=0.001, intermediate monocytes CCR2+ p=0.0003) in DCs and monocytes. Moreover, after the vaccination, old subjects showed a higher production of proinflammatory cytokines by monocytes in response to LPS (eg, IL6+;p=0.015), while young people showed a higher production of IFNα by plasmacytoid DCs after CpG-A stimulation (p=0.0009). Conclusion: The magnitude and polyfunctionality of SARS-CoV-2 specific T cell response is lower in old people, associated to a lower thymic function. In old people, the vaccination induced less immune activation and homing and the myeloid TLR-dependent response is directed towards a proinflammatory response, while in young people prevails IFNα production, related to a more effective antiviral response. These results support the additional boosting strategies in this vulnerable population.
ABSTRACT
Introduction: COVID-19 is a life-threatening disease leading to bilateral pneumonia and respiratory failure. The underlying reasons why a smaller percentage of patients present with severe pulmonary symptoms whereas the majority is only mildly affected, are to date not well understood. Methods: We analyzed immune cell dynamics in patients with mild (NIH Score 4+5) and severe (NIH Score 1-3) cases of SARS-CoV2 infection. Patients with mild courses presented with COVID-19 specific, mostly respiratory symptoms, however no one required treatment in the ICU, mechanical ventilation nor died due to COVID-19. Patients with a severe course of disease were treated in the ICU department of our hospital, all of them needed supplementary oxygen. Mortality rate of the cohort with severely ill patients was 33%. Results: Given that T cells play a critical role in the elimination of viral infections, we studied this lymphoid compartment in COVID-19 patients. Compared to healthy controls, patients with SARS-CoV2 infection presented increased T cell activation and proliferation and a decline of naive CD8 T-cells. Interestingly, activation markers on T cells were further enhanced in patients with severe courses of COVID-19 disease. Furthermore, the CD8 T-cell compartment in patients with mild COVID-19 exhibited a shift towards terminal differentiation. In contrast, severe cases showed an expansion of effector cells, which correlated with increased cell activation. To determine whether T-cells might be primed for homing to specific tissues during SARS-CoV-2 infection, we checked for particular chemokine receptors in our cohorts. We found the lung homing receptor CCR4 and the proinflammatory receptor CCR5 strongly upregulated on CD8 T-cells in patients with severe COVID-19 infection, mainly characterized by pulmonary failure and requirement of mechanical ventilation, however not in mild COVID-19 disease. Moreover, CD8 T-cells from patients with severe disease exhibited reduced CCR7 expression, pointing towards enhanced attracting to sites of inflammation and limited homing to secondary lymphoid organs. Further analysis revealed a linear relationship between CCR4 expression and CD8 T-cell activation and effector differentiation in patients with severe disease. Conclusion: Taken together, our data support the critical involvement of T cells in the pathogenesis of SARS-CoV2 infection and link clinical severity to T-cell hyperactivation and altered migratory capacity.