Prior SARS-CoV-2 infection enhances and reshapes spike protein-specific memory induced by vaccination.

The diversity of vaccination modalities and infection history are both variables that have an impact on the immune memory of individuals vaccinated against SARS-CoV-2. To gain more accurate knowledge of how these parameters imprint on immune memory, we conducted a long-term follow-up of SARS-CoV-2 spike protein-specific immune memory in unvaccinated and vaccinated COVID-19 convalescent individuals as well as in infection-naïve vaccinated individuals. Here, we report that individuals from the convalescent vaccinated (hybrid immunity) group have the highest concentrations of spike protein-specific antibodies at 6 months after vaccination. As compared with infection-naïve vaccinated individuals, they also display increased frequencies of an atypical mucosa-targeted memory B cell subset. These individuals also exhibited enhanced TH1 polarization of their SARS-CoV-2 spike protein-specific follicular T helper cell pool. Together, our data suggest that prior SARS-CoV-2 infection increases the titers of SARS-CoV-2 spike protein-specific antibody responses elicited by subsequent vaccination and induces modifications in the composition of the spike protein-specific memory B cell pool that are compatible with enhanced functional protection at mucosal sites.

T- and B-cell therapy in solid organ transplantation: current evidence and future expectations.

Cell therapy has emerged as an attractive therapeutic option in organ transplantation. During the last decade, the therapeutic potency of Treg immunotherapy has been shown in various preclinical animal models and safety was demonstrated in first clinical trials. However, there are still critical open questions regarding specificity, survival, and migration to the target tissue so the best Treg population for infusion into patients is still under debate. Recent advances in CAR technology hold the promise for Treg-functional superiority. Another exciting strategy is the generation of B-cell antibody receptor (BAR) Treg/cytotoxic T cells to specifically regulate or deplete alloreactive memory B cells. Finally, B cells are also capable of immune regulation, making them promising candidates for immunomodulatory therapeutic strategies. This article summarizes available literature on cell-based innovative therapeutic approaches aiming at modulating alloimmune response for transplantation. Crucial areas of investigation that need a joined effort of the transplant community for moving the field toward successful achievement of tolerance are highlighted.

Short and Long Term Clinical and Immunologic Follow up after Bone Marrow Mesenchymal Stromal Cell Therapy in Progressive Multiple Sclerosis-A Phase I Study.

Bone marrow derived mesenchymal stromal cells (BM-MSCs) have emerged as a possible new therapy for Multiple Sclerosis (MS), however studies regarding efficacy and in vivo immune response have been limited and inconclusive. We conducted a phase I clinical study assessing safety and clinical and peripheral immune responses after MSC therapy in MS. Seven patients with progressive MS were intravenously infused with a single dose of autologous MSC (1-2 × 106 MSCs/kg body weight). The infusions were safe and well tolerated when given during clinical remission. Five out of seven patients completed the follow up of 48 weeks post-infusion. Brain magnetic resonance imaging (MRI) showed the absence of new T2 lesions at 12 weeks in 5/6 patients, while 3/5 had accumulated new T2 lesions at 48 weeks. Patient expanded disability status scales (EDSS) were stable in 6/6 at 12 weeks but declined in 3/5 patients at 48 weeks. Early changes of circulating microRNA levels (2 h) and increased proportion of FOXP3+ Tregs were detected at 7 days post-infusion compared to baseline levels. In conclusion, MSC therapy was safe and well tolerated and is associated with possible transient beneficial clinical and peripheral immunotolerogenic effects.

Phenotypic and functional alterations of myeloid-derived suppressor cells during the disease course of multiple sclerosis.

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system involving dysregulated encephalitogenic T cells. Myeloid-derived suppressor cells (MDSCs) have been recognized for their important function in regulating T-cell responses. Recent studies have indicated a role for MDSCs in autoimmune diseases, but their significance in MS is not clear. Here, we assessed the frequencies of CD14+ HLA-DRlow monocytic MDSCs (Mo-MDSCs) and CD33+ CD15+ CD11b+ HLA-DRlow granulocytic MDSCs (Gr-MDSCs) and investigated phenotypic and functional differences of Mo-MDSCs at different clinical stages of MS and in healthy subjects (HC). Increased frequencies of Mo-MDSCs (P < 0.05) and Gr-MDSCs (P < 0.05) were observed in relapsing-remitting MS patients during relapse (RRMS-relapse) compared to stable RRMS (RRMS-rem). Secondary progressive MS (SPMS) patients displayed a decreased frequency of Mo-MDSCs and Gr-MDSCs compared to HC (P < 0.05). Mo-MDSCs within RRMS patients expressed significantly higher cell surface protein levels of CD86 and CD163 compared to SPMS patients. Mo-MDSCs within SPMS exhibited decreased mRNA expression of interleukin-10 and heme oxygenase 1 compared to RRMS and HC. Analysis of T-cell regulatory function of Mo-MDSCs demonstrated T-cell suppressive capacity in RRMS and HCs, while Mo-MDSCs of SPMS promoted autologous T-cell proliferation, which aligned with a differential cytokine profile compared to RRMS and HCs. This study is the first to show phenotypic and functional shifts of MDSCs between clinical stages of MS, suggesting a role for MDSCs as a therapeutic target to prevent MS disease progression.