Humoral and cellular immunity in three different types of COVID-19 vaccines against SARS-CoV-2 variants in a real-world data analysis

BackgroundAn effective vaccine response is currently a critical issue in the control of COVID-19. Little is known about humoral and cellular immunity comparing protein-based vaccine with other types of vaccines. The relevance of basal immunity to antibody production is also unknown.MethodsSeventy-eight individuals were enrolled in the study. The primary outcome were the level of spike-specific antibodies and neutralizing antibodies measured by ELISA. Secondary measures included memory T cells and basal immunity estimated by flow cytometry and ELISA. Correlations for all parameters were calculated using the nonparametric Spearman correlation method.ResultsWe observed that two doses of mRNA-based Moderna mRNA-1273 (Moderna) vaccine produced the highest total spike-binding antibody and neutralizing ability against the wild-type (WT), Delta, and Omicron variants. The protein-based MVC-COV1901 (MVC) vaccine developed in Taiwan produced higher spike-binding antibodies against Delta and Omicron variants and neutralizing ability against the WT strain than the adenovirus-based AstraZeneca-Oxford AZD1222 (AZ) vaccine. Moderna and AZ vaccination produced more central memory T cells in PBMC than the MVC vaccine. However, the MVC vaccine had the lowest adverse effects compared to the Moderna and AZ vaccines. Surprisingly, the basal immunity represented by TNF-α, IFN-γ, and IL-2 prior to vaccination was negatively correlated with the production of spike-binding antibodies and neutralizing ability.ConclusionThis study compared memory T cells, total spike-binding antibody levels, and neutralizing capacity against WT, Delta, and Omicron variants between the MVC vaccine and the widely used Moderna and AZ vaccines, which provides valuable information for future vaccine development strategies.     

Divergent SARS-CoV-2-specific T- and B-cell responses in severe but not mild COVID-19 patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the current coronavirus disease 2019 (COVID-19) pandemic. Understanding the immune response that provides specific immunity but may also lead to immunopathology is crucial for the design of potential preventive and therapeutic strategies. Here, we characterized and quantified SARS-CoV-2-specific immune responses in patients with different clinical courses. Compared to individuals with a mild clinical presentation, CD4⁺ T-cell responses were qualitatively impaired in critically ill patients. Strikingly, however, in these patients the specific IgG antibody response was remarkably strong. Furthermore, in these critically ill patients, a massive influx of circulating T cells into the lungs was observed, overwhelming the local T-cell compartment, and indicative of vascular leakage. The observed disparate T- and B-cell responses could be indicative of a deregulated immune response in critically ill COVID-19 patients.     

Spheromers reveal robust T cell responses to the Pfizer/BioNTech vaccine and attenuated peripheral CD8+ T cell responses post SARS-CoV-2 infection

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Long-term coexistence of SARS-CoV-2 with antibody response in COVID-19 patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causing coronavirus disease 2019 (COVID-19) has spread worldwide. Whether antibodies are important for the adaptive immune responses against SARS-CoV-2 infection needs to be determined. Here, 26 cases of COVID-19 in Jinan, China, were examined and shown to be mild or with common clinical symptoms, and no case of severe symptoms was found among these patients. Strikingly, a subset of these patients had SARS-CoV-2 and virus-specific IgG coexist for an unexpectedly long time, with two cases for up to 50 days. One COVID-19 patient who did not produce any SARS-CoV-2–bound IgG successfully cleared SARS-CoV-2 after 46 days of illness, revealing that without antibody-mediated adaptive immunity, innate immunity alone may still be powerful enough to eliminate SARS-CoV-2. This report may provide a basis for further analysis of both innate and adaptive immunity in SARS-CoV-2 clearance, especially in nonsevere cases.     

Increased Coexpression of PD-1, TIGIT,and KLRG-1 on Tumor-Reactive CD8+ T Cells During Relapse after Allogeneic Stem Cell Transplantation

Allogeneic stem cell transplantation (allo-SCT) can be a curative treatment for patients with a hematologic malignancy due to alloreactive T cell responses recognizing minor histocompatibility antigens (MiHA). Yet tumor immune escape mechanisms can cause failure of T cell immunity, leading to relapse. Tumor cells display low expression of costimulatory molecules and can up-regulate coinhibitory molecules that inhibit T cell functionality on ligation with their counter-receptors on the tumor-reactive T cells. The aim of this explorative study was to evaluate immune checkpoint expression profiles on T cell subsets and on cytomegalovirus (CMV)- and/or MiHA-reactive CD8⁺ T cells of allo-SCT recipients using a 13-color flow cytometry panel, and to correlate these expression patterns to clinical outcomes. MiHA-reactive CD8⁺ T cells exhibited an early differentiated CD27⁺⁺/CD28⁺⁺ phenotype with low KLRG-1 and CD57 expression. These T cells also displayed increased expression of PD-1, TIM-3, and TIGIT compared with total effector memory T cells and CMV-specific CD8⁺ T cells in healthy donors and allo-SCT recipients. Remarkably, high coexpression of PD-1, TIGIT, and KLRG-1 on MiHA-reactive CD8⁺ T cells was associated with relapse after allo-SCT. Taken together, these findings indicate that MiHA-specific CD8⁺ T cells of relapsed patients have a distinctive coinhibitory expression signature compared with patients who stay in remission. This phenotype may serve as a potential monitoring tool in patients. Moreover, these findings suggest that PD-1 and TIGIT play important roles in regulating T cell-mediated tumor control, providing a rationale for immunotherapy with blocking antibodies to treat relapse after allo-SCT.     

COVID-19 multisystem inflammatory syndrome in three teenagers with confirmed SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) is generally a relatively mild illness in children. An emerging disease entity coined as pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) has been reported recently, but is very rare and only affects a very small minority of children. Here we describe the clinical presentations and outcomes of three teenagers with serologically-confirmed SARS-CoV-2 infection admitted to a pediatric intensive care unit for PIMS-TS. Although their initial presentations were very similar, their COVID-19-related disease varied in severity.     

A whole blood test to measure SARS-CoV-2-specific response in COVID-19 patients

ObjectivesTo examine whether specific T-cell-responses to SARS-CoV-2 peptides can be detected in COVID-19 using a whole-blood experimental setting, which may be further explored as a potential diagnostic tool.MethodsWe evaluated interferon (IFN)-γ levels after stimulating whole-blood with spike and remainder-antigens peptides megapools (MP) derived from SARS-CoV-2 sequences; interleukin (IL)-1β, IL-1RA, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12p70, IL-13, IL-15, IL-17A, eotaxin, basic fibroblast growth factor (FGF), granulocyte-colony stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), IFN-γ, Interferon gamma-induced protein 10 (IP-10), monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1α, MIP-1β, Platelet-derived growth factor (PDGF), RANTES (regulated on activation, normal T cell expressed and secreted), tumour necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF) were also evaluated.ResultsIFN-γ-response to spike and remainder-antigens MPs was significantly increased in 35 COVID-19 patients compared with 29 ‘no COVID-19’ individuals (medians spike-MP: 0.26 vs 0, p = 0.0002; medians remainder-antigens-MP: 0.07 vs 0.02; p = 0.02).This response was detected independently of patients' clinical parameters. IFN-γ-response to SARS-CoV-2-unrelated antigens cytomegalovirus (CMV) and Staphylococcal Enterotoxin B (SEB) was similar in COVID-19 compared with ‘no COVID-19’ individuals (median CMV: 3.46 vs 5.28, p = 0.16; median SEB: 12.68 vs 15.05; p = 0.1). In response to spike-MPs in COVID-19- compared with ‘no COVID-19’ -individuals, we found significant higher median of IL-2 (50.08 vs 0, p = 0.0018), IFN-γ (90.16 vs 0, p = 0.01), IL-4 (0.52 vs 0, p = 0.03), IL-13 (0.84 vs 0, p = 0.007) and MCP-1 (4602 vs 359.2, p = 0.05).ConclusionsImmune response to SARS-CoV-2 peptides in a whole-blood assay is associated with COVID-19 and it is characterized by both Th1 and Th2 profile. This experimental approach may be useful for developing new T-cell based diagnostic tests for disease and vaccine settings.     

Neutralizing Antibody Responses to SARS-CoV-2 in Korean Patients Who Have Recovered from COVID-19

PurposeNeutralizing antibodies (NAbs) have been considered effective in preventing and treating viral infections. However, until now, the duration and clinical implications of antibody-mediated nature immunity in Koreans have remained unknown. Therefore, we examined NAbs levels and clinical characteristics in recovered coronavirus disease 2019 (COVID-19) patients.Materials and MethodsBlood samples were collected from 143 adult patients who had been diagnosed with and had recovered from COVID-19 from February to March in 2020 at a tertiary-care university-affiliated hospital in Daegu, Korea. A plaque reduction neutralization test was conducted to analyze NAb titers. Individualized questionnaires were used to identify patient clinical information.ResultsThe median number of days from symptom onset to the blood collection date was 109.0 (104.0; 115.0). The NAb titers ranged from 10 to 2560. The median NAb titer value was 40. Of the 143 patients, 68 (47.6%) patients had NAb titers ≥80, and 31 (21.7%) patients had NAb titers ≥160. The higher the age or disease severity, the higher the NAb titer. In univariate logistic regression, statistically significant predictors of high NAb titers (≥80) were age, myalgia, nausea or vomiting, dyspnea, and disease severity (p<0.05). Multivariable logistic regression showed that age ≥50 years (p=0.013) and moderate or higher disease severity (p<0.001) were factors associated with high NAb titers (≥80). None of the patients had reinfection of COVID-19.ConclusionAll recovered patients were found to have NAbs regardless of the NAb titers maintained by natural immunity. Age and disease severity during COVID-19 infection were associated with high NAb titers.     

Soluble PD-1 is Associated with Aberrant Regulation of T Cells Activation in Aplastic Anemia

Engagement of the membrane program death-1 (PD-1) receptor by its ligands suppresses T cell proliferation and cytokine production. Aberrant over-expression of costimulatory molecules, including PD-1, has been associated with persistent activation of self-reactive T cells in autoimmune diseases. However, the mechanism underlying the dysfunction of PD-1 in the regulation of T-cell activation in such diseases remains unclear. Here, we report the overexpression of CD4⁺ and CD8⁺ T cell PD-1 and elevated serum levels of soluble PD-1 in aplastic anemia (AA) patients. Detailed characterization of soluble PD-1 revealed that it corresponded to an alternative splice variant PD-1Δex3, which lacks the transmembrane domain but has a soluble extracellular domain of the PD-1 molecule. In a further study, PD-1 fusion protein displayed the ability of increasing the proliferation of T cells in vitro, which suggested that soluble PD-1 might serve as an autoimmune antibody to block the function of membrane-bound PD-1 on T cells and lead to aberrant T cell proliferation. Our study revealed a novel pathogenic pathway in which the function of overexpressed PD-1 to restrict over-self-reaction is counteracted by the excessive production of soluble PD-1.     

Screening HLA-A-restricted T cell epitopes of SARS-CoV-2 and the induction of CD8+ T cell responses in HLA-A transgenic mice

Since severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-specific T cells have been found to play essential roles in host immune protection and pathology in patients with coronavirus disease 2019 (COVID-19), this study focused on the functional validation of T cell epitopes and the development of vaccines that induce specific T cell responses. A total of 120 CD8⁺ T cell epitopes from the E, M, N, S, and RdRp proteins were functionally validated. Among these, 110, 15, 6, 14, and 12 epitopes were highly homologous with SARS-CoV, OC43, NL63, HKU1, and 229E, respectively; in addition, four epitopes from the S protein displayed one amino acid that was distinct from the current SARS-CoV-2 variants. Then, 31 epitopes restricted by the HLA-A2 molecule were used to generate peptide cocktail vaccines in combination with Poly(I:C), R848 or poly (lactic-co-glycolic acid) nanoparticles, and these vaccines elicited robust and specific CD8⁺ T cell responses in HLA-A2/DR1 transgenic mice as well as wild-type mice. In contrast to previous research, this study established a modified DC-peptide-PBL cell coculture system using healthy donor PBMCs to validate the in silico predicted epitopes, provided an epitope library restricted by nine of the most prevalent HLA-A allotypes covering broad Asian populations, and identified the HLA-A restrictions of these validated epitopes using competitive peptide binding experiments with HMy2.CIR cell lines expressing the indicated HLA-A allotype, which initially confirmed the in vivo feasibility of 9- or 10-mer peptide cocktail vaccines against SARS-CoV-2. These data will facilitate the design and development of vaccines that induce antiviral CD8⁺ T cell responses in COVID-19 patients.     

Human CXCR5+PD-1+ CD8 T cells in healthy individuals and patients with hematologic malignancies

Immune checkpoint blockade (ICB) has revolutionized cancer therapy, but varying response rates illustrate the need for biomarkers of response. Studies in mice have identified a subset of CD8 T cells that is essential for response to PD-1 ICB. These CD8 T cells co-express CXCR5, PD-1 and Tcf1, and provide effector T cells upon PD-1 ICB. It is unknown whether similar T cells play a role in PD-1 ICB in humans. We studied human peripheral blood and lymph nodes (LNs) for the frequency, phenotype, and functionality of CXCR5⁺PD-1⁺ CD8 T cells. We find that CXCR5⁺PD-1⁺ CD8 T cells are memory-like cells, express Tcf1, and lack expression of effector molecules. CXCR5⁺PD-1⁺ CD8 T cells produce cytokines upon stimulation, but have limited proliferative capacity. We studied patients with hematologic malignancies with varying response rates to PD-1 ICB. Specifically in chronic lymphocytic leukemia, in which PD-1 ICB does not induce clinical responses, CXCR5⁺PD-1⁺ CD8 T cells show loss of the memory phenotype and increased effector differentiation. In conclusion, we identified CXCR5⁺PD-1⁺ CD8 T cells in human peripheral blood and LN, which could play a similar role during PD-1 ICB. Future studies should analyze CXCR5⁺PD-1⁺ CD8 T cells during PD-1 ICB and their importance for therapeutic response.     

Upregulation of CCR4 in activated CD8+ T cells indicates enhanced lung homing in patients with severe acute SARS-CoV-2 infection

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. Comparing the immunological phenotype in healthy donors and patients with mild versus severe COVID-19 shows that in COVID-19 patients, NK-/B-cell activation and proliferation are enhanced independent of severity. As an important precondition for effective antibody responses, T-follicular helper cells and antibody secreting cells are increased both in patients with mild and severe SARS-CoV-2 infection. Beyond this, T cells in COVID-19 patients exhibit a stronger activation profile with differentiation toward effector cell phenotypes. Importantly, when looking at the rates of pulmonary complications in COVID-19 patients, the chemokine receptor CCR4 is higher expressed by both CD4 and CD8 T cells of patients with severe COVID-19. This raises the hypothesis that CCR4 upregulation on T cells in the pathogenesis of COVID-19 promotes stronger T-cell attraction to the lungs leading to increased immune activation with presumably higher pulmonary toxicity. Our study contributes significantly to the understanding of the immunological changes during COVID-19, as new therapeutic agents, preferentially targeting the immune system, are highly warranted.     

系统性红斑狼疮患者外周血CD4+CD25high Tr和 CD4+CD25low T细胞PD-1表达的分析和意义

目的 探讨PD-1(programmed death-1)在系统性红斑狼疮(systemic lupus erythematosus,SLE)患者外周血CD4+ CD25high调节性T细胞(regulatory T cell,Tr)和CD4+ CD25lowT细胞上的表达及临床意义.方法 应用流式细胞仪检测51例SLE患者和38例健康对照者外周血CD4+ CD25high Tr和CD4+ CD25lowT细胞表面PD-1表达水平,同时收集SLE患者临床表现、实验室检查数据,比较SLE稳定组、活动组和健康对照组以及狼疮肾炎组和无狼疮肾炎组之间CD4+ CD25 high Tr和CD4+CD25lowT细胞表PD-1表达的百分比,并分析其与临床表现及实验室检查数据的相关性.结果 (1)SLE活动组和稳定组外周血CD4+ CD25 high Tr和CD4+ CD25lowT细胞的百分率均低于对照组.(2)SLE活动组和稳定组外周血CD4+ CD25 highTr表达PD-1的百分率均高于对照组.SLE稳定组和对照组外周血CD4+ CD25lowT细胞表达PD-1的百分率均高于活动组.(3)狼疮肾炎患者外周血CD4+CD25highTr表达PD-1的百分率高于无狼疮肾炎患者.而狼疮肾炎患者CD4+ CD25lowT细胞表达PD-1的百分率低于无狼疮肾炎患者.(4) CD4+CD25high PD-1+T细胞百分率与SLEDAI评分呈正相关;CD4+ CD25high Tr、CD4+CD25lowPD-1+T细胞百分率与SLEDAI评分呈负相关.结论 SLE患者外周血中CD4+ CD25high Tr、CD4+ CD25lowT细胞以及它们表面PD-1表达异常,并且与疾病活动性相关,PD-1/PD-L1信号通路可能对CD4+CD25highTr、CD4+CD25lowT细胞的数量和功能有影响.     

CD8+ T cells specific for an immunodominant SARS-CoV-2 nucleocapsid epitope display high naive precursor frequency and TCR promiscuity

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