The vaccinia-based Sementis Copenhagen Vector coronavirus disease 2019 vaccine induces broad and durable cellular and humoral immune responses.

The ongoing coronavirus disease 2019 (COVID-19) pandemic perpetuated by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has highlighted the continued need for broadly protective vaccines that elicit robust and durable protection. Here, the vaccinia virus-based, replication-defective Sementis Copenhagen Vector (SCV) was used to develop a first-generation COVID-19 vaccine encoding the spike glycoprotein (SCV-S). Vaccination of mice rapidly induced polyfunctional CD8 T cells with cytotoxic activity and robust type 1 T helper-biased, spike-specific antibodies, which are significantly increased following a second vaccination, and contained neutralizing activity against the alpha and beta variants of concern. Longitudinal studies indicated that neutralizing antibody activity was maintained up to 9 months after vaccination in both young and middle-aged mice, with durable immune memory evident even in the presence of pre-existing vector immunity. Therefore, SCV-S vaccination has a positive immunogenicity profile, with potential to expand protection generated by current vaccines in a heterologous boost format and presents a solid basis for second-generation SCV-based COVID-19 vaccine candidates incorporating additional SARS-CoV-2 immunogens.

Regulatory B Cells: Dark Horse in Pregnancy Immunotherapy?

There are many unanswered questions surrounding the function of immune cells and how they interact with the reproductive system to support successful pregnancy or contribute to pregnancy pathologies. While the role of immune cells such as uterine natural killer and dendritic cells, and more recently regulatory T cells has been established, the role of another major immune cell population, the B cell, and particularly the regulatory B cells, is relatively poorly understood. This review outlines what is known about B-cell subsets in the context of pregnancy, what constitutes a regulatory B cell and what role they may play, particularly during early pregnancy. Lastly, we discuss why immunotherapies for the treatment of pregnancy disorders is not widely progressed clinically and speculate on the potential of functional regulatory B cells as the basis of novel immunotherapeutic approaches for the treatment of immune-based pregnancy pathologies.

Polyinosinic: Polycytidylic Acid and Murine Cytomegalovirus Modulate Expression of Murine IL-10 and IL-21 in White Adipose Tissue.

White adipose tissue (WAT) produces interleukin-10 and other immune suppressors in response to pathogen-associated molecular patterns (PAMPs). It also homes a subset of B-cells specialized in the production of IL-10, referred to as regulatory B-cells. We investigated whether viral stimuli, polyinosinic: polycytidylic acid (poly(I:C)) or whole replicative murine cytomegalovirus (MCMV), could stimulate the expression of IL-10 in murine WAT using in vivo and ex vivo approaches. Our results showed that in vivo responses to systemic administration of poly(I:C) resulted in high levels of endogenously-produced IL-10 and IL-21 in WAT. In ex vivo WAT explants, a subset of B-cells increased their endogenous IL-10 expression in response to poly(I:C). Finally, MCMV replication in WAT explants resulted in decreased IL-10 levels, opposite to the effect seen with poly(I:C). Moreover, downregulation of IL-10 correlated with relatively lower number of Bregs. To our knowledge, this is the first report of IL-10 expression by WAT and WAT-associated B-cells in response to viral stimuli.

Trophoblasts promote induction of a regulatory phenotype in B cells that can protect against detrimental T cell-mediated inflammation.

PROBLEM: A successful outcome to pregnancy is critically dependent on the initiation of maternal immune tolerance before embryo implantation. Cells of embryonic origin that come in contact with the uterine microenvironment can exert influence over the phenotype and function of immune cells to facilitate robust implantation; however, what influence they may have on B cells remains unknown. In this study, we investigate the effect of human trophoblast cells on B-cell phenotype and the subsequent effect on peri-implantation events. METHOD OF STUDY: We cultured purified human B cells with the first-trimester human trophoblast cell line Swan 71 to investigate trophoblast-B-cell interactions and utilized trophoblast spheroids in an in vitro implantation model of migration and invasion. RESULTS: Trophoblast-educated B cells or TE-B cells were found to consist of B cells in committed lineages such as plasmablasts and memory B cells, as well as increased proportions in subsets of CD24hi CD27+ regulatory B cells and CD19+ IL-10+ B cells. Conditioned media from the TE-B cells showed reduced production of pro-inflammatory cytokines that influenced the T-cell proliferation and cytokine production. Using trophoblast spheroids, we assessed the role of TE-B cells in trophoblast invasion and migration. Our results demonstrate a protective effect of TE-B-conditioned media against deleterious inflammation as evidenced by survival of the trophoblast spheroid in the presence of an immune assault and promotion of a migratory phenotype. CONCLUSION: We posit that trophoblast-mediated education of B cells leads to their acquisition of properties capable of modulating inflammation in the uterine environment during the peri-implantation period.

Uterine B Cells Exhibit Regulatory Properties During the Peri-Implantation Stage of Murine Pregnancy.

A successful outcome to pregnancy is dependent on the ability of the maternal uterine microenvironment to regulate inflammation processes and establish maternal tolerance. Recently, B cells have been shown to influence pregnancy outcomes as aberrations in their numbers and functions are associated with obstetric complications. In this study, we aimed to comprehensively examine the population frequency and phenotypic profile of B cells over the course of murine pregnancy. Our results demonstrated a significant expansion in B cells within the uterus during the peri-implantation period, accompanied by alterations in B cell phenotype. Functional evaluation of uterine B cells purified from pregnant mice at day 5.5 post-coitus established their regulatory capacity as evidenced by effective suppression of proliferation and activation of syngeneic CD4+ T cells. Flow cytometric analysis revealed that the uterine B cell population has an expanded pool of IL-10-producing B cells bearing upregulated expression of co-stimulatory molecules CD80 and CD86 and activation marker CD27. Our investigations herein demonstrate that during the critical stages surrounding implantation, uterine B cells are amplified and phenotypically modified to act in a regulatory manner that potentially contributes toward the establishment of maternal immunological tolerance in early pregnancy.

Isolation and Structural Characterization of Echinocystic Acid Triterpenoid Saponins from the Australian Medicinal and Food Plant Acacia ligulata.

The Australian plant Acacia ligulata has a number of traditional food and medicinal uses by Australian Aboriginal people, although no bioactive compounds have previously been isolated from this species. Bioassay-guided fractionation of an ethanolic extract of the mature pods of A. ligulata led to the isolation of the two new echinocystic acid triterpenoid saponins, ligulatasides A (1) and B (2), which differ in the fine structure of their glycan substituents. Their structures were elucidated on the basis of 1D and 2D NMR, GC-MS, LC-MS/MS, and saccharide linkage analysis. These are the first isolated compounds from A. ligulata and the first fully elucidated structures of triterpenoid saponins from Acacia sensu stricto having echinocystic acid reported as the aglycone. Compounds 1 and 2 were evaluated for cytotoxic activity against a human melanoma cancer cell line (SK-MEL28) and a diploid fibroblast cell line (HFF), but showed only weak activity.

Regulatory B Cells in Pregnancy: Lessons from Autoimmunity, Graft Tolerance, and Cancer.

The success of pregnancy is contingent on the maternal immune system recognizing and accommodating a growing semi-allogeneic fetus. Specialized subsets of lymphocytes capable of negative regulation are fundamental in this process, and include the regulatory T cells (Tregs) and potentially, regulatory B cells (Bregs). Most of our current understanding of the immune regulatory role of Bregs comes from studies in the fields of autoimmunity, transplantation tolerance, and cancer biology. Bregs control autoimmune diseases and can elicit graft tolerance by inhibiting the differentiation of effector T cells and dendritic cells (DCs), and activating Tregs. Furthermore, in cancer, Bregs are hijacked by neoplastic cells to promote tumorigenesis. Pregnancy therefore represents a condition that reconciles these fields-mechanisms must be in place to ensure maternal immunological tolerance throughout gravidity to allow the semi-allogeneic fetus to grow within. Thus, the mechanisms underlying Breg activities in autoimmune diseases, transplantation tolerance, and cancer may take place during pregnancy as well. In this review, we discuss the potential role of Bregs as guardians of pregnancy and propose an endocrine-modulated feedback loop highlighting the Breg-Treg-tolerogenic DC interface essential for the induction of maternal immune tolerance.

Evaluation of trained immunity by ß-1, 3 (d)-glucan on murine monocytes in vitro and duration of response in vivo.

The ß-1, 3 (d)-glucan (ß-glucan) present in the cell wall of Candida albicans induces epigenetic changes in human monocytes resulting in primed macrophages exhibiting increased cytokine responsiveness to reinfection. This phenomenon is referred to as trained immunity or innate immune memory. However, whether ß-glucan can reprogramme murine monocytes in vitro or induce lasting effects in vivo has yet to be elucidated. Thus, purified murine spleen-derived monocytes were primed with ß-glucan in vitro and assessed for markers of differentiation and survival. Important macrophage cell markers during monocyte-to-macrophage differentiation were downregulated and survival enhanced due to partial inhibition of apoptosis. Increased survival and not the ß-glucan training effect explained the elevated production of tumour necrosis factor-α (TNFα) and interleukin-6 (IL-6) induced by subsequent lipopolysaccharide (LPS) challenge. In vivo, 4 days after systemic administration of ß-glucan, mice were more responsive to LPS challenge as shown by the increased serum levels of TNFα, IL-6 and IL-10, an effect shown to be short lived as enhanced cytokine production was lost by day 20. Here, we have characterised murine macrophages derived from ß-glucan-primed monocytes based on their surface marker expression and for the first time provide evidence that the training effect of ß-glucan in vivo declines within a 3-week period.