T cells play a vital role in combatting SARS-CoV-2 and forming long-term memory responses. Whereas extensive structural information is available on neutralizing antibodies against SARS-CoV-2, such ...information on SARS-CoV-2-specific T-cell receptors (TCRs) bound to their peptide-MHC targets is lacking. Here we determine the structures of a public and a private TCR from COVID-19 convalescent patients in complex with HLA-A2 and two SARS-CoV-2 spike protein epitopes (YLQ and RLQ). The structures reveal the basis for selection of particular TRAV and TRBV germline genes by the public but not the private TCR, and for the ability of the TCRs to recognize natural variants of RLQ but not YLQ. Neither TCR recognizes homologous epitopes from human seasonal coronaviruses. By elucidating the mechanism for TCR recognition of an immunodominant yet variable epitope (YLQ) and a conserved but less commonly targeted epitope (RLQ), this study can inform prospective efforts to design vaccines to elicit pan-coronavirus immunity.
Th1 lymphocytes are considered the main mediators of protection against tuberculosis (TB); however, their phenotypic characteristics and relationship with Th17 and Th1Th17 populations during TB are ...poorly understood. We have analyzed Th1, Th17, and Th1Th17 lymphocytes in the blood and pulmonary lesions of TB patients. The populations were identified based on the production of IFN-γ and/or IL-17 and the coexpression of CXCR3 (X3) and CCR6 (R6). In the blood, IL-17
and IFN-γ
IL-17
lymphocytes were barely detectable (median, <0.01% of CD4
lymphocytes), whereas IFN-γ
lymphocytes predominated (median, 0.45%). Most IFN-γ
lymphocytes (52%) were X3
R6
, suggesting their "nonclassical" (ex-Th17) nature. In the lungs, IL-17
and IFN-γ
IL-17
lymphocytes were more frequent (0.3%,
< 0.005), yet IFN-γ
cells predominated (11%). Phenotypically, lung CD4
cells were X3
R6
The degree of differentiation of blood effector CD4
lymphocytes (evaluated based on CD62L/CD27/CD28 coexpression) increased as follows: X3
R6
< X3
R6
< X3
R6
, with X3
R6
cells being largely terminally differentiated CD62L
CD27
CD28
cells. Lung CD4
lymphocytes were highly differentiated, recalling blood X3
R6
populations. Following in vitro stimulation with anti-CD3/anti-CD28 Abs, X3
R6
CD4
lymphocytes converted into X3
R6
and X3
R6
cells. The results demonstrate that, during active TB, Th1 lymphocytes predominate in blood and lungs, document differences in X3/R6 expression by blood and lung CD4
cells, and link the pattern of X3/R6 expression with the degree of cell differentiation. These findings add to the understanding of immune mechanisms operating during TB and are relevant for the development of better strategies to control it.
It is generally thought that
(
)-specific CD4
Th1 cells producing IFN-γ are essential for protection against tuberculosis (TB). In some studies, protection has recently been associated with ...polyfunctional subpopulation of
-specific Th1 cells, i.e., with cells able to simultaneously secrete several type 1 cytokines. However, the role for
-specific Th1 cells and their polyfunctional subpopulations during established TB disease is not fully defined. Pulmonary TB is characterized by a great variability of disease manifestations. To address the role for
-specific Th1 responses during TB, we investigated how Th1 and other immune cells correlated with particular TB manifestations, such as the degree of pulmonary destruction, TB extent, the level of bacteria excretion, clinical disease severity, clinical TB forms, and "Timika X-ray score," an integrative parameter of pulmonary TB pathology. In comparison with healthy
-exposed controls, TB patients (TBP) did not exhibit deficiency in
-specific cytokine-producing CD4
cells circulating in the blood and differed by a polyfunctional profile of these cells, which was biased toward the accumulation of bifunctional TNF-α
IFN-γ
IL-2
lymphocytes. Importantly, however, severity of different TB manifestations was not associated with
-specific cytokine-producing cells or their polyfunctional profile. In contrast, several TB manifestations were strongly correlated with leukocyte numbers, the percent or the absolute number of lymphocytes, segmented or band neutrophils. In multiple alternative statistical analyses, band neutrophils appeared as the strongest positive correlate of pulmonary destruction, bacteria excretion, and "Timika X-ray score." In contrast, clinical TB severity was primarily and inversely correlated with the number of lymphocytes in the blood. The results suggest that: (i) different TB manifestations may be driven by distinct mechanisms; (ii) quantitative parameters and polyfunctional profile of circulating
-specific CD4
cells play a minor role in determining TB severity; and (iii) general shifts in production/removal of granulocytic and lymphocytic lineages represent an important factor of TB pathogenesis. Mechanisms leading to these shifts and their specific role during TB are yet to be determined but are likely to involve changes in human hematopoietic system.
In peripheral tissues, immune protection critically depends on the activity of tissue resident macrophages, which makes our understanding of the biology of these cells of great significance. Until ...recently, human macrophage studies were largely based on the analysis of monocyte-derived macrophages that differ from tissue resident macrophages by many characteristics. To model tissue resident macrophages, methods of generating macrophages from pluripotent stem cells have been developed. However, the immunological properties of macrophages derived from pluripotent stem cells remain under-investigated. In this study, we aimed to perform the multifarious immunological characteristics of macrophages generated from human induced pluripotent stem cells (iMϕs), including an analysis of their phenotype, secretory and antibacterial activities, as well as their comparison with macrophages derived from blood monocytes and infected lung tissue. We report that iMϕs displayed the morphology and the CD11b
CD45
CD14
phenotype typical for mononuclear phagocytes. The cells co-expressed markers known to be associated with classically (CD80, CD86, CCR5) and alternatively (CD163 and CD206) activated macrophages, with a bias toward a higher expression of the latter. iMϕs secreted pro-inflammatory (IL-6, CXCL8, CCL2, CCL4, CXCL1, CXCL10) and anti-inflammatory (IL-10, IL-1RA, CCL22) cytokines with a high IL-10/IL-12p70 index (>20). iMϕs were phagocytic and restricted
growth
by >75%. iMϕs differed from blood monocytes/macrophages by a lower expression level of HLA-DR and the CD14
CD16
phenotype and shared several phenotypic characteristics with lung macrophages. In response to LPS, iMϕs up-regulated HLA-DR and produced TNF-α. IFN-γ increased iMϕ reactivity to LPS, but did not increase iMϕ mycobactericidal capacity. The results characterize iMϕs as differentiated but low-activated/low-polarized "naïve-like" macrophages that are capable of mounting inflammatory and antibacterial responses when exposed to inflammatory stimuli or pathogens. iMϕs represent a valuable model for studying antibacterial responses of tissue resident macrophages and for developing approaches to modulating macrophage activity.
To determine the immunogenicity, efficacy, reactogenicity, and safety of a single dose of recombinant adenovirus type-5 vectored COVID-19 vaccine (Ad5-nCoV, 5 × 1010 viral particles per 0.5 mL dose), ...we conducted a single-dose, randomised, double-blind, placebo-controlled, parallel group (3:1 Ad5-nCoV:placebo), phase 3 trial (Prometheus).
From 11-September-2020 to 05-May-2021, across six sites in the Russian Federation, 496 participants were injected with either placebo or Ad5-nCoV expressing the full-length spike (S) protein from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Seroconversion (the primary endpoint) rates of 78.5% (95% CI: 73.9; 82.6) against receptor binding domain (RBD), 90.6% (95% CI: 87.2; 93.4) against S protein and 59.0% (95% CI: 53.3; 64.6) seroconversion of neutralising antibodies against SARS-CoV-2 at 28 days post-vaccination were observed. Geometric mean titres (GMTs) were also elevated for antibodies against the RBD (405 95% CI: 366; 449) and S protein (677 95% CI: 608; 753) compared to the GMT of neutralising antibodies against SARS-CoV-2 (16.7 95% CI: 15.3; 18.3). Using an IFN-γ ELISpot assay after stimulating the cells with recombinant S protein ectodomain we showed that the Ad5-nCoV vaccine induced the most robust cellular immune response on Days 14 and 28. Up to Day 28, the primary and all secondary endpoints of the Ad5-nCoV vaccine were statistically significant compared with the placebo (р<0.001). Systemic reactions were reported in 113 of 496 (22.8%) participants (Ad5-nCoV, 26.9%; Placebo, 10.5%), and local reactions were reported in 108 (21.8%) participants (Ad5-nCoV, 28.5%; Placebo, 1.6%). These were generally mild and resolved within 7 days after vaccination. Of the six serious adverse events reported, none of the events were vaccine related. There were no deaths or premature withdrawals.
A single-dose of Ad5-nCoV vaccine induced a marked specific humoral and cellular immune response with a favourable safety profile.
Trial registration: ClinicalTrials.gov: NCT04540419.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mesenchymal stromal cells (MSC) have strong immunomodulatory properties and therefore can be used to control inflammation and tissue damage. It was suggested recently that MSC injections can be used ...to treat multi-drug resistant tuberculosis (TB). However, MSC trafficking and immunomodulatory effects of MSC injections during Mycobacterium tuberculosis (Mtb) infection have not been studied. To address this issue we have analyzed MSC distribution in tissues and local immunological effects of MSC injections in Mtb infected and uninfected mice. After intravenous injection, MSC accumulated preferentially in the lungs where they were located as cell aggregates in the alveolar walls. Immunological analysis of MSC effects included detection of activated, IFN-γ and IL-4 producing CD4+ lymphocytes, the frequency analysis of dendritic cells (CD11c+F4/80) and macrophages (CD11c-F4/80+) located in the lungs, the expression of IA/IE and CD11b molecules by these cells, and evaluation of 23 cytokines/chemokines in lung lysates. In the lungs of uninfected mice, MSC transfer markedly increased the percentage of IFN-γ+ CD4+ lymphocytes and dendritic cells, elevated levels of IA/IE expression by dendritic cells and macrophages, augmented local production of type 2 cytokines (IL-4, IL-5, IL-10) and chemokines (CCL2, CCL3, CCL4, CCL5, CXCL1), and downregulated type 1 and hematopoietic cytokines (IL-12p70, IFN-γ, IL-3, IL-6, GM-CSF). Compared to uninfected mice, Mtb infected mice had statistically higher "background" frequency of activated CD69+ and IFN-γ+ CD4+ lymphocytes and dendritic cells, and higher levels of cytokines in the lungs. The injections of MSC to Mtb infected mice did not show statistically significant effects on CD4+ lymphocytes, dendritic cells and macrophages, only slightly shifted cytokine profile, and did not change pathogen load or slow down TB progression. Lung section analysis showed that in Mtb infected mice, MSC could not be found in the proximity of the inflammatory foci. Thus, in healthy recipients, MSC administration dramatically changed T-cell function and cytokine/chemokine milieu in the lungs, most likely, due to capillary blockade. But, during Mtb infection, i.e., in the highly-inflammatory conditions, MSC did not affect T-cell function and the level of inflammation. The findings emphasize the importance of the evaluation of MSC effects locally at the site of their predominant post-injection localization and question MSC usefulness as anti-TB treatment.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Adenovirus vaccines, particularly the COVID-19 Ad5-nCoV adenovirus vaccine, have emerged as promising tools in the fight against infectious diseases. In this study, we investigated the structure of ...the T cell response to the Spike protein of the SARS-CoV-2 virus used in the COVID-19 Ad5-nCoV adenoviral vaccine in a phase 3 clinical trial (NCT04540419). In 69 participants, we collected peripheral blood samples at four time points after vaccination or placebo injection. Sequencing of T cell receptor repertoires from Spike-stimulated T cell cultures at day 14 from 17 vaccinated revealed a more diverse CD4
T cell repertoire compared to CD8
. Nevertheless, CD8
clonotypes accounted for more than half of the Spike-specific repertoire. Our longitudinal analysis showed a peak T cell response at day 14, followed by a decline until month 6. Remarkably, multiple T cell clonotypes persisted for at least 6 months after vaccination, as demonstrated by ex vivo stimulation. Examination of CDR3 regions revealed homologous sequences in both CD4
and CD8
clonotypes, with major CD8
clonotypes sharing high similarity with annotated sequences specific for the NYNYLYRLF peptide, suggesting potential immunodominance. In conclusion, our study demonstrates the immunogenicity of the Ad5-nCoV adenoviral vaccine and highlights its ability to induce robust and durable T cell responses. These findings provide valuable insight into the efficacy of the vaccine against COVID-19 and provide critical information for ongoing efforts to control infectious diseases.
Understanding the hallmarks of the immune response to SARS-CoV-2 is critical for fighting the COVID-19 pandemic. We assessed antibody and T cell reactivity in convalescent COVID-19 patients and ...healthy donors sampled both prior to and during the pandemic. Healthy donors examined during the pandemic exhibited increased numbers of SARS-CoV-2-specific T cells, but no humoral response. Their probable exposure to the virus resulted in either asymptomatic infection without antibody secretion or activation of preexisting immunity. In convalescent patients, we observed a public and diverse T cell response to SARS-CoV-2 epitopes, revealing T cell receptor (TCR) motifs with germline-encoded features. Bulk CD4+ and CD8+ T cell responses to the spike protein were mediated by groups of homologous TCRs, some of them shared across multiple donors. Overall, our results demonstrate that the T cell response to SARS-CoV-2, including the identified set of TCRs, can serve as a useful biomarker for surveying antiviral immunity.
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•Healthy donors sampled in 2020 had an increased T cell response to SARS-CoV-2•SARS-CoV-2 glycoprotein S-specific TCR repertoire features public CDR3 motifs•Two epitopes are recognized by the majority of the HLA-A2+ COVID-19 convalescents
Shomuradova et al. assessed the immune response to SARS-CoV-2 in convalescent patients and healthy donors. Antigen-specific T cells were increased in convalescents and in donors sampled during the pandemic. The work identified two public epitopes from S-glycoprotein. T cell receptor repertoire profiling of S-glycoprotein-specific lymphocytes revealed public CDR3 motifs.
During the ongoing coronavirus disease COVID-19 pandemic, many individuals were infected with and have cleared the virus, developing virus-specific antibodies and effector/memory T cells. An ...important unanswered question is what levels of T cell and antibody responses are sufficient to protect from the infection.
In 5340 Moscow residents, we evaluated anti-SARS-CoV-2 IgM/IgG titers and frequencies of the T cells specific to the membrane, nucleocapsid, and spike proteins of SARS-CoV-2, using IFNγ ELISpot assay. Additionally, we evaluated the fractions of virus-specific CD4+ and CD8+ T cells using intracellular staining of IFNγ and IL2 followed by flow cytometry. We analyzed the COVID-19 rates as a function of the assessed antibody and T cell responses, using the Kaplan-Meyer estimator method, for up to 300 days post-inclusion.
We showed that T cell and antibody responses are closely interconnected and are commonly induced concurrently. Magnitudes of both responses inversely correlated with infection probability. Individuals positive for both responses demonstrated the highest levels of protectivity against the SARS-CoV-2 infection. A comparable level of protection was found in individuals with antibody response only, while the T cell response by itself granted only intermediate protection.
We found that the contribution of the virus-specific antibodies to protection against the SARS-CoV-2 infection is more pronounced than that of the T cells. The data on the virus-specific IgG titers may be instructive for making decisions in personalized health care and public anti-COVID-19 policies.
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