1,721,329 research outputs found
IL-15 in T-Cell Responses and Immunopathogenesis
No full textIL-15 belongs to the common gamma chain cytokine family and has pleiotropic immunological functions. IL-15 is a homeostatic cytokine essential for the development and maintenance of NK cells and memory CD8+ T cells. In addition, IL-15 plays a critical role in the activation, effector functions, tissue residency, and senescence of CD8+ T cells. IL-15 also activates virtual memory T cells, mucosal-associated invariant T cells and γδ T cells. Recently, IL-15 has been highlighted as a major trigger of TCR-independent activation of T cells. This mechanism is involved in T cell-mediated immunopathogenesis in diverse diseases, including viral infections and chronic inflammatory diseases. Deeper understanding of IL-15-mediated T-cell responses and their underlying mechanisms could optimize therapeutic strategies to ameliorate host injury by T cell-mediated immunopathogenesis. This review highlights recent advancements in comprehending the role of IL-15 in relation to T cell responses and immunopathogenesis under various host conditions. © 2024. The Korean Association of Immunologists.11Nsciescopuskc
Human CD8+ T-Cell Populations That Express Natural Killer Receptors
No full textCD8+ T cells are activated by TCRs that recognize specific cognate Ags, while NK-cell activation is regulated by a balance between signals from germline-encoded activating and inhibitory NK receptors. Through these different processes of Ag recognition, CD8+ T cells and NK cells play distinct roles as adaptive and innate immune cells, respectively. However, some human CD8+ T cells have been found to express activating or inhibitory NK receptors. CD8+ T-cell populations expressing NK receptors straddle the innate-adaptive boundary with their innate-like features. Recent breakthrough technical advances in multi-omics analysis have enabled elucidation of the unique immunologic characteristics of these populations. However, studies have not yet fully clarified the heterogeneity and immunological characteristics of each CD8+ T-cell population expressing NK receptors. Here we aimed to review the current knowledge of various CD8+ T-cell populations expressing NK receptors, and to pave the way for delineating the landscape and identifying the various roles of these T-cell populations. © 2023, Korean Association of Immunologists. All rights reserved.11Nsciescopuskc
KIR+CD8+ and NKG2A+CD8+ T cells are distinct innate-like populations in humans
No full textSubsets of the human CD8+ T cell population express inhibitory NK cell receptors, such as killer immunoglobulin-like receptors (KIRs) and NKG2A. In the present study, we examine the phenotypic and functional characteristics of KIR+CD8+ T cells and NKG2A+CD8+ T cells. KIRs and NKG2A tend to be expressed by human CD8+ T cells in a mutually exclusive manner. In addition, TCR clonotypes of KIR+CD8+ T cells barely overlap with those of NKG2A+CD8+ T cells, and KIR+CD8+ T cells are more terminally differentiated and replicative senescent than NKG2A+CD8+ T cells. Among cytokine receptors, IL12Rβ1, IL12Rβ2, and IL18Rβ are highly expressed by NKG2A+CD8+ T cells, whereas IL2Rβ is expressed by KIR+CD8+ T cells. IL-12/IL-18-induced production of IFN-γ is prominent in NKG2A+CD8+ T cells, whereas IL-15-induced NK-like cytotoxicity is prominent in KIR+CD8+ T cells. These findings suggest that KIR+CD8+ and NKG2A+CD8+ T cells are distinct innate-like populations with different cytokine responsiveness. © 2023 The Author(s)11Nsciescopu
Dynamic Responses of Circulating T Cells After Stereotactic Body Radiation Therapy for Bone Metastasis in Patients With Breast Cancer
No full textPurpose: Preclinical studies have shown that radiation therapy modulates antitumor immune responses. However, circulating T-cell responses after radiation therapy in patients with cancer have been poorly characterized. This study aims to explore the changes in circulating T cells after stereotactic body radiation therapy (SBRT). Methods and Materials: Peripheral blood samples of 30 patients with breast cancer who underwent SBRT for bone metastasis were analyzed using multicolor flow cytometry. Phenotypes of PD-1+ CD8+ T cells and regulatory T (TREG) cells were examined. Additionally, plasma protein levels were analyzed using a bead-based immunoassay. Results: Circulating PD-1+ CD8+ T cells, which are enriched for tumor-specific clonotypes, were activated at 1 week after SBRT. However, circulating TREG cells were also activated after SBRT; this pattern was also evident among effector Foxp3hiCD45RA− TREG cells. We observed no difference in T-cell responses according to the fraction size and number. Notably, activation of TREG cells was more prominent in patients who experienced greater activation of PD-1+ CD8+ T cells. Plasma level changes in TGF-β1, soluble CTLA-4, and soluble 4-1BB at 1 week after SBRT were associated with PD-1+ CD8+ T-cell responses. Activation of TREG cells at 1 week after SBRT was associated with worse progression-free survival. Clinical factors including molecular subtype were not associated with the T-cell responses. Conclusions: SBRT induced activation of both potentially tumor-specific CD8+ T cells and TREG cells, which were tightly associated with each other. These results may support the use of TREG cell-modulating strategies with SBRT to improve the antitumor immune response. © 2023 Elsevier Inc.11Nsciescopu
Corticosteroids reduce pathologic interferon responses by downregulating STAT1 in patients with high-risk COVID-19
No full textWe do not yet understand exactly how corticosteroids attenuate hyperinflammatory responses and alleviate high-risk coronavirus disease 2019 (COVID-19). We aimed to reveal the molecular mechanisms of hyperinflammation in COVID-19 and the anti-inflammatory effects of corticosteroids in patients with high-risk COVID-19. We performed single-cell RNA sequencing of peripheral blood mononuclear cells (PBMCs) from three independent COVID-19 cohorts: cohort 1 was used for comparative analysis of high-risk and low-risk COVID-19 (47 PBMC samples from 28 patients), cohort 2 for longitudinal analysis during COVID-19 (57 PBMC samples from 15 patients), and cohort 3 for investigating the effects of corticosteroid treatment in patients with high-risk COVID-19 (55 PBMC samples from 13 patients). PBMC samples from healthy donors (12 PBMC samples from 12 donors) were also included. Cohort 1 revealed a significant increase in the proportion of monocytes expressing the long noncoding RNAs NEAT1 and MALAT1 in high-risk patients. Cohort 2 showed that genes encoding inflammatory chemokines and their receptors were upregulated during aggravation, whereas genes related to angiogenesis were upregulated during improvement. Cohort 3 demonstrated downregulation of interferon-stimulated genes (ISGs), including STAT1, in monocytes after corticosteroid treatment. In particular, unphosphorylated STAT-dependent ISGs enriched in monocytes from lupus patients were selectively downregulated by corticosteroid treatment in patients with high-risk COVID-19. Corticosteroid treatment suppresses pathologic interferon responses in monocytes by downregulating STAT1 in patients with high-risk COVID-19. Our study provides insights into the mechanisms underlying COVID-19 aggravation and improvement and the effects of corticosteroid treatment. © 2023, The Author(s).11Nsciescopuskc
Omicron Subvariants, Including BA.4 and BA.5, Substantially Preserve T Cell Epitopes of Ancestral SARS-CoV-2
Full text link[No abstract available]11Nsciescopuskc
Distinctive Dynamics and Functions of the CD4+CD25+FOXP3+ Regulatory T Cell Population in Patients with Severe and Mild COVID-19
No full textAlthough CD4+CD25+FOXP3+ regulatory T (TREG) cells have been studied in patients with COVID-19, changes in the TREG cell population have not been longitudinally examined during the course of COVID-19. In this study, we longitudinally investigated the quantitative and qualitative changes in the TREG cell population in patients with COVID-19. We found that the frequencies of total TREG cells and CD45RA-FOXP3hi activated TREG cells were significantly increased 15-28 d postsymptom onset in severe patients, but not in mild patients. TREG cells from severe patients exhibited not only increased proliferation but also enhanced apoptosis, suggesting functional derangement of the TREG cell population during severe COVID-19. The suppressive functions of the TREG cell population did not differ between patients with severe versus mild COVID-19. The frequency of TREG cells inversely correlated with SARS-CoV-2-specific cytokine production by CD4+ T cells and their polyfunctionality in patients with mild disease, suggesting that TREG cells are major regulators of virus-specific CD4+ T cell responses during mild COVID-19. However, such correlations were not observed in patients with severe disease. Thus, in this study, we describe distinctive changes in the TREG cell population in patients with severe and mild COVID-19. Our study provides a deep understanding of host immune responses upon SARS-CoV-2 infection in regard to TREG cells. Copyright © 2023 by The American Association of Immunologists, Inc.11Nsciescopu
A heterologous AZD1222 priming and BNT162b2 boosting regimen more efficiently elicits neutralizing antibodies, but not memory T cells, than the homologous BNT162b2 regimen
No full textBackground: Comparative analyses of SARS-CoV-2-specific immune responses elicited by diverse primeboost regimens are required to establish efficient regimens for the control of COVID-19.
Method: In this prospective observational cohort study, spike-specific immunoglobulin G (IgG) and neutralizing antibodies (nAbs) alongside spike-specific T-cell responses in age-matched groups of homologous BNT162b2/BNT162b2 or AZD1222/AZD1222 vaccination, heterologous AZD1222/BNT162b2
vaccination, and prior wild-type SARS-CoV-2 infection/vaccination were evaluated.
Results: Peak immune responses were achieved after the second vaccine dose in the naïve vaccinated
groups and after the first dose in the prior infection/vaccination group. Peak titers of anti-spike IgG
and nAb were significantly higher in the AZD1222/BNT162b2 vaccination and prior infection/vaccination
groups than in the BNT162b2/BNT162b2 or AZD1222/AZD1222 groups. However, the frequency of
interferon-c-producing CD4+ T cells was highest in the BNT162b2/BNT162b2 vaccination group.
Similar results were observed in the analysis of polyfunctional T cells. When nAb and CD4+ T-cell
responses against the Delta variant were analyzed, the prior infection/vaccination group exhibited higher
responses than the groups of other homologous or heterologous vaccination regimens.
Conclusion: nAbs are efficiently elicited by heterologous AZD1222/BNT162b2 vaccination, as well as prior
infection/vaccination, whereas spike-specific CD4+ T-cell responses are efficiently elicited by homologous
BNT162b2 vaccination. Variant-recognizing immunity is more efficiently generated by prior infection/-
vaccination than the other homologous or heterologous vaccination regimens.11Nsciescopu
Increased type III interferons and NK cell functions in SARS-CoV-2-infected children
No full text[No abstract available]11Nsciescopu
Better understanding CD8+ T cells in cancer and viral infections
No full textThe first conference on 'Infection and Immunity' was organized by the Institute for Basic Science and Korean Association of Immunologists and held in Daejeon, South Korea, from 12 to 14 July 2023. The conference focused on the biology of CD8+ T cells in the context of viral disease and cancer.11Nsciescopu
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