Native and IgE-primed rat peritoneal mast cells exert pro-inflammatory activity and migrate in response to yeast zymosan upon Dectin-1 engagement

Hyaluronic acid-modified yeast β-glucan particles delivering doxorubicin for treatment of breast cancer

Breast cancer is one of the most threatening cancers that poses a great risk to women's health. The anti-tumor drug doxorubicin (DOX) is one of commonly used drugs in the treatment of breast cancer. However, the cytotoxicity of DOX has always been an urgent challenge to be solved. In this study, we report an alternative drug delivery system delivering DOX for reducing its physiological toxicity by using the yeast β-glucan particle (YGP) with a hollow and porous vesicle structure. Briefly, amino groups were grafted onto the surface of YGP with the silane coupling agent, then the oxidized hyaluronic acid (OHA) was attached by Schiff base reaction to get HA-modified YGP (YGP@N=C-HA), finally DOX was encapsulated into YGP@N=C-HA to get DOX-loaded YGP@N=C-HA (YGP@N=C-HA/DOX). In vitro release experiments exhibited the pH-responsive DOX release from YGP@N=C-HA/DOX. Cell experiments displayed that YGP@N=C-HA/DOX had good killing effect on both MCF-7 and 4T1 cells and could be internalized into these cells through CD44 receptors, showing targetability to cancer cells. Furthermore, YGP@N=C-HA/DOX could effectively inhibit tumor growth and reduce the physiological toxicity of DOX. Thus, the YGP-based vesicle provides an alternative strategy for lowering the physiological toxicity of DOX in the medical treatment of breast cancer.

Do Mast Cells Contribute to the Antifungal Host Defense?

The fungal kingdom includes a group of microorganisms that are widely distributed in the environment, and therefore the exposure to them is almost constant. Furthermore, fungal components of the microbiome, i.e., mycobiome, could serve as a reservoir of potentially opportunistic pathogens. Despite close encounters with fungi, defense mechanisms that develop during fungal infections remain unexplored. The strategic location of mast cells (MCs) close to the external environment places them among the first cells to encounter pathogens along with the other innate immune cells. MCs are directly involved in the host defense through the ability to destroy pathogens or indirectly by activating other immune cells. Most available data present MCs’ involvement in antibacterial, antiviral, or antiparasitic defense mechanisms. However, less is known about their contribution in defense mechanisms against fungi. MCs may support immune responses to fungi or their specific molecules through initiated degranulation, synthesis and release of cytokines, chemokines, mediators, and generation of reactive oxygen species (ROS), as well as immune cells’ recruitment, phagocytosis, or provision of extracellular DNA traps. This review summarizes current knowledge on host defense mechanisms against fungi and MCs’ involvement in those processes. It also describes the effects of fungi or fungus-derived constituents on MCs’ activity.

The Emerging Role of Mast Cells in Response to Fungal Infection

Mast cells (MCs) have been considered as the core effector cells of allergic diseases. However, there are evidence suggesting that MCs are involved in the mechanisms of fungal infection. MCs are mostly located in the border between host and environment and thus may have easy contact with the external environmental pathogens. These cells express receptors which can recognize pathogen-associated molecular patterns such as Toll-like receptors (TLR2/4) and C-type Lectins receptors (Dectin-1/2). Currently, more and more data indicate that MCs can be interacted with some fungi (Candida albicans, Aspergillus fumigatus and Sporothrix schenckii). It is demonstrated that MCs can enhance immunity through triggered degranulation, secretion of cytokines and chemokines, neutrophil recruitment, or provision of extracellular DNA traps in response to the stimulation by fungi. In contrast, the involvement of MCs in some immune responses may lead to more severe symptoms, such as intestinal barrier function loss, development of allergic bronchial pulmonary aspergillosis and increased area of inflammatory in S. schenckii infection. This suggests that MCs and their relevant signaling pathways are potential treatment regimens to prevent the clinically unwanted consequences. However, it is not yet possible to make definitive statements about the role of MCs during fungal infection and/or pathomechanisms of fungal diseases. In our article, we aim to review the function of MCs in fungal infections from molecular mechanism to signaling pathways, and illustrate the role of MCs in some common host-fungi interactions.