| 1. |
- Johansson, Emil, et al.
(författare)
-
Hierarchical Clustering and Trajectory Analyses Reveal Viremia-Independent B-Cell Perturbations in HIV-2 Infection
- 2022
-
Ingår i: Cells. - : MDPI. - 2073-4409. ; 11:19
-
Tidskriftsartikel (refereegranskat)abstract
- Time to AIDS in HIV-2 infection is approximately twice as long compared to in HIV-1 infection. Despite reduced viremia, HIV-2-infected individuals display signs of chronic immune activation. In HIV-1-infected individuals, B-cell hyperactivation is driven by continuous antigen exposure. However, the contribution of viremia to B-cell perturbations in HIV-2-infected individuals remains largely unexplored. Here, we used polychromatic flow cytometry, consensus hierarchical clustering and pseudotime trajectory inference to characterize B-cells in HIV-1- or HIV-2-infected and in HIV seronegative individuals. We observed increased frequencies of clusters containing hyperactivated T-bethighCD95highCD27int and proliferating T-bet+CD95highCD27+CD71+ memory B-cells in viremic HIV-1 (p < 0.001 and p < 0.001, respectively), viremic HIV-2 (p < 0.001 and p = 0.014, respectively) and in treatment-naïve aviremic HIV-2 (p = 0.004 and p = 0.020, respectively)-infected individuals, compared to seronegative individuals. In contrast, these expansions were not observed in successfully treated HIV-1-infected individuals. Finally, pseudotime trajectory inference showed that T-bet-expressing hyperactivated and proliferating memory B-cell populations were located at the terminal end of two trajectories, in both HIV-1 and HIV-2 infections. As the treatment-naïve aviremic HIV-2-infected individuals, but not the successfully ART-treated HIV-1-infected individuals, showed B-cell perturbations, our data suggest that aviremic HIV-2-infected individuals would also benefit from antiretroviral treatment.
|
|
| 2. |
- Lundgren, Anna, 1974, et al.
(författare)
-
Plasmablasts in previously immunologically naive COVID-19 patients express markers indicating mucosal homing and secrete antibodies cross-reacting with SARS-CoV-2 variants and other beta-coronaviruses
- 2023
-
Ingår i: Clinical and Experimental Immunology. - 0009-9104 .- 1365-2249. ; 213:2, s. 173-89
-
Tidskriftsartikel (refereegranskat)abstract
- Antigen-specific class-switched antibodies are detected at the same time or even before IgM in serum of non-vaccinated individuals infected with SARS-CoV-2. These derive from the first wave of plasmablasts formed. Hence, the phenotype and specificity of plasmablasts can reveal information about early B-cell activation. Here we have analyzed B cells and plasmablasts circulating in blood of COVID-19 patients not previously exposed to SARS-CoV-2 during and after disease. We find that during infection with the original Wuhan strain, plasmablasts in blood produce IgA1, IgG1, and IgM, and that most express CCR10 and integrin beta 1, only some integrin beta 7, while the majority lack CCR9. Plasmablast-secreted antibodies are reactive to the spike (S) and nucleocapsid (N) proteins of the Wuhan strain as well as later variants of concern, but also bind S proteins from endemic and non-circulating betacoronaviruses. In contrast, after recovery, antibodies produced from memory B cells target variants of SARS-CoV-2 and SARS-CoV-1 but compared to previously non-infected individuals do not show increased binding to endemic coronaviruses. This suggests that the early antibody response to a large extent stems from pre-existing cross-reactive class-switched memory B cells, and that although newly formed memory cells target the novel SARS-CoV-2 virus the numbers of broadly cross-reactive memory B cells do not increase extensively. The observations give insight into the role of pre-existing memory B cells in early antibody responses to novel pathogens and may explain why class-switched antibodies are detected early in the serum of COVID-19 patients. During an infection, plasmablasts circulating in blood represent ongoing formation of antibody-producing cells from activated B cells. Here we study the early plasmablasts in previously naive COVID-19 patients arriving at hospital. We find extensive cross-reactivity to circulating and non-circulating beta-coronaviruses, that IgA1 responses dominate, and that the cells express markers suggesting mucosal homing.
|
|
| 3. |
- Scharf, Lydia
(författare)
-
Immune deterioration in HIV-1 and HIV-2 infection with a focus on CD8 T cell exhaustion
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Thanks to the development of antiretroviral treatment (ART), human immunodeficiency virus (HIV) infection is now considered a chronic infection rather than the death sentence it used to be. Despite constant expansion and improvement of treatment options, even optimal therapy cannot prevent the impact of HIV on the human immune system. Persistence of latently infected cells, low-level residual viral replication and long-term impact from initial tissue damage lead to chronic immune activation, which in turn drives a number of comorbidities and complications that lower the patient´s quality of life. The hallmark of HIV infection is the depletion of CD4 T cells, also called helper T cells. In addition to immune activation due to the virus itself, the lack of support by CD4 T cells impairs numerous immune cell types. As the main defender against viral infections, CD8 T cells play a central role in ending the peak of viral replication during acute HIV infection. However, during the subsequent chronic phase, they become exhausted, which impairs not only immune responses against HIV, but also other viral infections and malignant cells. In paper I we investigate the role of the immune receptor TIGIT in HIV type 1 (HIV-1) infection. As an exhaustion marker, it is increased in HIV-1 infection, co-expressed with other inhibitory receptors and fails to return to normal levels despite viral suppression by ART. It is also part of a regulation network together with the complementary co-stimulator CD226 and their shared ligand PVR. All members of this network are skewed in HIV-1 infection and contribute to CD8 T cell exhaustion and immune deterioration. Of the few human genetic factors beneficial in HIV-1 infection, HLA-B*57 has the potential to slow down disease progression. Paper II investigates the connection between HLA-B*57 and exhaustion of HIV-specific CD8 T cells. Delayed co-expression of TIGIT and PD-1 might be one factor contributing to slower disease progression often seen in people positive for the HLA-B*57 allele. HIV type 2 (HIV-2) is associated with slower disease progression and a higher chance of virus control by the host immune system than HIV-1. In paper III, we found signs of CD8 T cell pathogenesis, especially a skewed balance of co-stimulation and inhibition, in HIV-2 infection despite controlled viral replication. HIV-1 pathogenesis in children after mother-to-child transmission shows differences from pathogenesis in adult patients and leads to unique complications. To better understand the unique aspects of pediatric HIV infection and potentially find candidates for therapeutic intervention, we investigated plasma biomarkers in well treated children in paper IV. Their treatment prevents high levels of dysregulation in comparison to HIV-negative children. However increased levels of sTRAIL, a marker for T cell activation with potential to induce apoptosis, shows the capacity to further optimize treatment in HIV infected children.
|
|
| 4. |
- Scharf, Lydia, et al.
(författare)
-
Inverted CD8 T-Cell Exhaustion and Co-Stimulation Marker Balance Differentiate Aviremic HIV-2-Infected From Seronegative Individuals
- 2021
-
Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- HIV-2 is less pathogenic compared to HIV-1. Still, disease progression may develop in aviremic HIV-2 infection, but the driving forces and mechanisms behind such development are unclear. Here, we aimed to reveal the immunophenotypic pattern associated with CD8 T-cell pathology in HIV-2 infection, in relation to viremia and markers of disease progression. The relationships between pathological differences of the CD8 T-cell memory population and viremia were analyzed in blood samples obtained from an occupational cohort in Guinea-Bissau, including HIV-2 viremic and aviremic individuals. For comparison, samples from HIV-1- or dually HIV-1/2-infected and seronegative individuals were obtained from the same cohort. CD8 T-cell exhaustion was evaluated by the combined expression patterns of activation, stimulatory and inhibitory immune checkpoint markers analyzed using multicolor flow cytometry and advanced bioinformatics. Unsupervised multidimensional clustering analysis identified a cluster of late differentiated CD8 T-cells expressing activation (CD38+, HLA-DRint/high), co-stimulatory (CD226+/-), and immune inhibitory (2B4+, PD-1high, TIGIThigh) markers that distinguished aviremic from viremic HIV-2, and treated from untreated HIV-1-infected individuals. This CD8 T-cell population displayed close correlations to CD4%, viremia, and plasma levels of IP-10, sCD14 and beta-2 microglobulin in HIV-2 infection. Detailed analysis revealed that aviremic HIV-2-infected individuals had higher frequencies of exhausted TIGIT+ CD8 T-cell populations lacking CD226, while reduced percentage of stimulation-receptive TIGIT-CD226+ CD8 T-cells, compared to seronegative individuals. Our results suggest that HIV-2 infection, independent of viremia, skews CD8 T-cells towards exhaustion and reduced co-stimulation readiness. Further knowledge on CD8 T-cell phenotypes might provide help in therapy monitoring and identification of immunotherapy targets.
|
|
| 5. |
- Scharf, Lydia, et al.
(författare)
-
Longitudinal single-cell analysis of SARS-CoV-2-reactive B cells uncovers persistence of early-formed, antigen specific clones.
- 2023
-
Ingår i: JCI insight. - : American Society for Clinical Investigation. - 2379-3708. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding persistence and evolution of B cell clones after COVID-19 infection and vaccination is crucial for predicting responses against emerging viral variants and optimizing vaccines. Here, we collected longitudinal samples from severe COVID-19 patients every third to seventh day during hospitalization and every third month after recovery. We profiled the antigen-specific immune cell dynamics by combining single cell RNA-Seq, Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE)-Seq, B cell receptor (BCR)-Seq with oligo-tagged antigen baits. While the proportion of Spike Receptor Binding Domain-specific memory B cells (MBC) increased from 3 months after infection, the other Spike- and Nucleocapsid-specific B cells remained constant. All patients showed ongoing class switching and sustained affinity maturation of antigen specific cells, which was not significantly increased early after vaccine. B cell analysis revealed a polyclonal response with limited clonal expansion; nevertheless, some clones detected during hospitalization, as plasmablasts, persisted for up to one year, as MBC. Monoclonal antibodies derived from persistent B cell families increased their binding and neutralization breadth and started recognizing viral variants by 3 months after infection. Overall, our findings provide important insights into the clonal evolution and dynamics of antigen specific B cell responses in longitudinally sampled COVID-19 infected patients.
|
|
