Regulatory B cells (Bregs) participate in auto-tolerance maintenance and immune homeostasis. Despite their impact on many diseases and due to the difficulty to define them, knowledge about their origin and their physiological inducers is still unclear. The incomplete understanding about the generation of Bregs and their limited numbers in periphery make it difficult to develop Breg-based therapy. Therefore, identifying factors that promote their development would allow their ex-vivo production in order to create new immunotherapy. This project aims to test the capacity of several cytokines (Interleukin 1-beta (IL-1β), Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF), and Cluster of differentiation 40 ligand (CD40L)) and bacteria-derived oligodeoxynucleotides (CpG-ODN), alone or in combination, to generate B cells with regulatory phenotype and function. We have demonstrated that the Breg-associated phenotypes were heterogeneous between one and other stimulation conditions. However, the expression of other markers related to Bregs such as IL-10, CD80, CD86, CD71, Programmed cell death-1 (PD-1), and Programmed death-ligand 1 (PD-L1) was increased when cells were stimulated with CpG alone or in combination. Moreover, stimulated B cells presented a suppressive function on autologous activated peripheral blood mononuclear cells (PBMC) proliferation. Therefore, this work is the first step to demonstrate the feasibility to induce functional Breg-like cells in vitro and will then facilitate the way to produce Breg-like cells as a potential future cellular therapy.

In our work, we analyzed the role of the CD100/CD72 and PD-1/PD-L1 axes in immune response dysfunction in human immunodeficiency virus (HIV)-1 infection in which high expressions of PD-1 and PD-L1 were associated with an immunosuppressive state via limitation of the HIV-1-specific T-cell responses. CD100 was demonstrated to play a relevant role in immune responses in various pathological processes and may be responsible for immune dysregulation during HIV-1 infection. We investigated the function of CD72/CD100, and PD-1/PDL-1 axes on T and B cells in HIV-infected individuals and in healthy individuals. We analyzed the frequencies and fluorescence intensities of these four markers on CD4+, CD8+ T and B cells. Marker expressions were increased during active HIV-1 infection. CD100 frequency on T cells was positively associated with the expression of PD-1 and PD-L1 on T cells from HIV-infected treatment-naïve individuals. In addition, the frequency of CD72-expressing T cells was associated with interferon gamma (IFN-γ) production in HIV-infected treatment-naïve individuals. Our data suggest that the CD72/CD100 and PD-1/PD-L1 axes may jointly participate in dysregulation of immunity during HIV-1 infection and could partially explain the immune systems’ hyper-activation and exhaustion.

Since December 2019, the coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread throughout the world. To eradicate it, it is crucial to acquire a strong and long-lasting anti-SARS-CoV-2 immunity, by either natural infection or vaccination. We collected blood samples 12–305 days after positive polymerase chain reactions (PCRs) from 35 recovered individuals infected by SARS-CoV-2. Peripheral blood mononuclear cells were stimulated with SARS-CoV-2-derived peptide pools, such as the spike (S), nucleocapsid (N) and membrane (M) proteins, and we quantified anti-S immunoglobulins in plasma. After 10 months post-infection, we observed a sustained SARS-CoV-2-specific CD4+ T-cell response directed against M-protein, but responses against S- or N-proteins were lost over time. Besides, we demonstrated that O-group individuals presented significantly lower frequencies of specific CD4+ T-cell responses against Pep-M than non O-group individuals. The non O-group subjects also needed longer to clear the virus, and they lost cellular immune responses over time, compared to the O-group individuals, who showed a persistent specific immune response against SARS-CoV-2. Therefore, the S-specific immune response was lost over time, and individual factors might determine the sustainability of the body’s defenses, which must be considered in the future design of vaccines to achieve continuous anti-SARS-CoV-2 immunity.

Vaccination against SARS-CoV-2 has become the main method of reducing mortality and severity of COVID-19. This work aims to study the evolution of the cellular and humoral responses conferred by two mRNA vaccines after two doses against SARS-CoV-2. On days 30 and 240 after the second dose of both vaccines, the anti-S antibodies in plasma were evaluated from 82 volunteers vaccinated with BNT162b2 and 68 vaccinated with mRNA-1273. Peripheral blood was stimulated with peptides encompassing the entire SARS-CoV-2 Spike sequence. IgG Anti-S antibodies (humoral) were quantified on plasma, and inflammatory cytokines (cellular) were measured after stimulation. We observed a higher response (both humoral and cellular) with the mRNA-1273 vaccine. Stratifying by age and gender, differences between vaccines were observed, especially in women under 48 and men over 48 years old. Therefore, this work could help to set up a vaccination strategy that could be applied to confer maximum immunity.

This study examines the relationship between regulatory B (Breg) and T (Treg) compartments, which play crucial roles in the maintenance of immune homeostasis in the context of HIV. Using flow cytometry, the phenotypes of different Breg and Treg subsets from HIV-infected and healthy individuals were analyzed, along with the suppressive capacity of Breg. Peripheral blood samples of thirteen HIV + treatment-naïve individuals, fourteen treated-HIV + individuals with undetectable viral load and twelve healthy individuals were analyzed. The absolute counts of Breg and Treg subsets were decreased in HIV + treatment-naïve individuals in comparison to treated-HIV + and healthy individuals. Interestingly, correlations between Breg subsets (CD24 hi CD27 + and PD-L1 + B cells) and IL-10-producing Breg observed in healthy individuals were lost in HIV + treatment-naïve individuals. However, a correlation between frequencies of CD24 hi CD38 hi or TIM-1 + -Breg subsets and Treg was observed in HIV + treatment-naïve individuals and not in healthy individuals. Therefore, we hypothesized that various Breg subsets might have different functions during B and T-cell homeostasis during HIV-1 infection. In parallel, stimulated Breg from HIV-infected treatment-naïve individuals presented a decreased ability to suppress CD4 + T-cell proliferation in comparison to the stimulated Breg from treated-HIV + or healthy individuals. We demonstrate a dysregulation between Breg and Treg subsets in HIV-infected individuals, which might participate in the hyper-activation and exhaustion of the immune system that occurs in such patients.

No abstract

Since December 2019, the coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread throughout the world. To eradicate it, it is crucial to acquire a strong and long-lasting anti-SARS-CoV-2 immunity, by either natural infection or vaccination. We collected blood samples 12-305 days after positive polymerase chain reactions (PCRs) from 35 recovered individuals infected by SARS-CoV-2. Peripheral blood mononuclear cells were stimulated with SARS-CoV-2-derived peptide pools, such as the Spike (S), Nucleocapsid (N), and Membrane (M) proteins, and we quantified anti-S immunoglobulins in plasma. After 10 months post-infection, we observed a sustained SARS-CoV-2-specific CD4+ T-cell response directed against M-protein, but responses against S- or N-proteins were lost over time. Besides, we demonstrated that A-group individuals presented significantly higher frequencies of specific CD4+ T-cell responses against Pep-M than O-group individuals. The A-group subjects also needed longer to clear the virus and they lost cellular immune responses over time, compared to the O-group individuals, who showed a persistent specific immune response against SARS-CoV-2. Therefore, the S-specific immune response was lost over time, and individual factors determine the sustainability of the body's defences, which must be considered in the future design of vaccines to achieve continuous anti-SARS-CoV-2 immunity.

Regulatory T cells (Tregs), which are characterized by the expression of the transcription factor forkhead box P3 (FOXP3), are the main immune cells that induce tolerance and are regulators of immune homeostasis. Natural Treg cells (nTregs), described as CD4+CD25+FOXP3+, are generated in the thymus via activation and cytokine signaling. Transforming growth factor beta type 1 (TGF-β1) is pivotal to the generation of the nTreg lineage, its maintenance in the thymus, and to generating induced Treg cells (iTregs) in the periphery or in vitro arising from conventional T cells (Tconvs). Here, we tested whether TGF-β1 treatment, associated with interleukin-2 (IL-2) and CD3/CD28 stimulation, could generate functional Treg-like cells from human thymocytes in vitro, as it does from Tconvs. Additionally, we genetically manipulated the cells for ectopic FOXP3 expression, along with the TGF-β1 treatment. We demonstrated that TGF-β1 and ectopic FOXP3, combined with IL-2 and through CD3/CD28 activation, transformed human thymocytes into cells that expressed high levels of Treg-associated markers. However, these cells also presented a lack of homogeneous suppressive function and an unstable proinflammatory cytokine profile. Therefore, thymocyte-derived cells, activated with the same stimuli as Tconvs, were not an appropriate alternative for inducing cells with a Treg-like phenotype and function.