Staphylococcal aureus (S. aureus), a Gram-positive bacteria, is known to cause various infections. Extracellular vesicles (EVs) are a heterogeneous array of membranous structures secreted by cells from all three domains of life, i.e., eukaryotes, bacteria, and archaea. Bacterial EVs are implied to be involved in both bacteria–bacteria and bacteria–host interactions during infections. It is still unclear how S. aureus EVs interact with host cells and induce inflammatory responses. In this study, EVs were isolated from S. aureus and mutant strains deficient in either prelipoprotein lipidation (Δlgt) or major surface proteins (ΔsrtAB). Their immunostimulatory capacities were assessed both in vitro and in vivo. We found that S. aureus EVs induced pro-inflammatory responses both in vitro and in vivo. However, this activity was dependent on lipidated lipoproteins (Lpp), since EVs isolated from the Δlgt showed no stimulation. On the other hand, EVs isolated from the ΔsrtAB mutant showed full immune stimulation, indicating the cell wall anchoring of surface proteins did not play a role in immune stimulation. The immune stimulation of S. aureus EVs was mediated mainly by monocytes/macrophages and was TLR2 dependent. In this study, we demonstrated that not only free Lpp but also EV-imbedded Lpp had high pro-inflammatory activity.

Aging alters immunoglobulin production, affecting the humoral immune response. Toll-like receptor 2 (TLR2) recognizes Staphylococcus aureus (S. aureus) which causes bacteremia with high mortality in the elderly. To understand how TLR2 and aging affect the humoral immune response in bacteremia, four groups of mice (wild type-young, wild type-old, TLR2−/−-young, and TLR2−/−-old) were used to analyze immunoglobulin levels in healthy conditions as well as 10 days after intravenous injection with S. aureus. We found that aging increased the levels of both IgM and IgG. Increased IgG in aged mice was controlled by TLR2. In bacteremia infection, aged mice failed to mount proper IgM response in both wild-type (WT) and TLR2−/− mice, whereas IgG response was impaired in both aged and TLR2−/− mice. Aged mice displayed reduced IgG1 and IgG2a response irrespective of TLR2 expression. However, impaired IgG2b response was only found in aged WT mice and not in TLR2−/− mice. Both aging and TLR2−/− increased the levels of anti-staphylococcal IgM in bacteremia. Aging increased sialylated IgG in WT mice but not in TLR2−/− mice. IgG sialylation was not affected by the infection in neither of the mice. In summary, aging increases all immunoglobulins except IgG1. However, aged mice fail to mount a proper antibody response to S. aureus bacteremia. TLR2 plays the regulatory role in IgG but not IgM response to infection.

Staphylococcus aureus (S. aureus) causes a broad range of infections. TLR2 senses the S. aureus lipoproteins in S. aureus infections. Aging raises the risk of infection. Our aim was to understand how aging and TLR2 impact the clinical outcomes of S. aureus bacteremia. Four groups of mice (Wild type/young, Wild type/old, TLR2-/-/young, and TLR2-/-/old) were intravenously infected with S. aureus, and the infection course was followed. Both TLR2 deficiency and aging enhanced the susceptibility to disease. Increased age was the main contributing factor to mortality and changes in spleen weight, whereas other clinical parameters such as weight loss and kidney abscess formation were more TLR2 dependent. Importantly, aging increased mortality without relying on TLR2. In vitro, both aging and TLR2 deficiency downregulated cytokine/chemokine production of immune cells with distinct patterns. In summary, we demonstrate that aging and TLR2 deficiency impair the immune response to S. aureus bacteremia in distinct ways.

For full list of author affiliations and declarations see end of paper Fertility preservation methods for prepubertal women about to undergo gonadotoxic chemo and/or radiation therapy are limited. Therefore, the aim of this study was to investigate the feasibility to develop an alternative fertility preservation method based on an ex vivo perfusion platform for whole ewe ovaries. Thirteen ewe ovaries were divided into two groups (group 1 and 2) that were perfused in a bioreactor for up to 7 days. Group 1 (n = 3) were stimulated with human menopausal gonadotropin (hMG) administered in single daily dose, while group 2 (n = 10) were stimulated continuously for 24 h. The perfused ovaries in group 1 showed no significant differences in follicular density, sub-follicular morphology and oocyte quality after ischaemia and after ex vivo perfusion compared with non-perfused control ovaries. The perfused ovaries in group 2 showed a significant decrease in the follicular reserve and oocyte quality compared with the control group. In total, 16 GV-MI oocytes were retrieved from both groups. This study describes for the first time the ex vivo maintenance of viable follicles of ewe ovaries with oocyte integrity and the retrieval of oocytes after ex vivo hormonal perfusion with two different protocols for up to 7 days.

Biological scaffold or implant is a popular choice for the preparation of tissue-engineered organs and has the potential to address donor shortage in the clinics. However, biological scaffolds prepared by physical or chemical agents cause damage to the extracellular matrix by potentially inducing immune responses after implantation. The current study explores an alternative route for the preparation of acellular scaffolds and explores the fate of the prepared scaffolds in a milieu of immune cells following implantation without using immunosuppressant. Using the syngeneic (Lewis male-Lewis female) and allogeneic (Brown Norway male-Lewis female) models and different tissue routes (subcutaneous vs omentum) for transplantation, normal blood vascular scaffolds were implanted which was converted to acellular vascular scaffolds by in vivo natural decellularization at the end of 2 months of observation. We also prepared chemically decellularized acellular scaffolds from normal untreated blood vascular scaffolds using a cocktail of chemicals which was also similarly placed in subcutaneous and omentum sites. Here, we applied in-depth quantitative proteomics along with histology and image analysis to comprehensively describe and compare the proteome of the natural and chemically decellularized scaffold. Our data confirm that site-specific advantages exist in modulating the ECM and regulating the immune responses (macrophage and T cells) following implantation, which possibly led to the production of an acellular scaffold (natural decellularization) under in vivo conditions. The current approach opens up the possibility to create tailor-made acellular scaffolds to build functional blood vessels. In addition, the identification of different tissue sites facilitates differential immune response against the scaffolds. This study provides a rich resource aimed toward an enhanced mechanistic understanding to study immune responses under similar settings in the field of transplantation and regenerative medicine.