Mast Cell Response to Parasites: from Recognition and Activation to Host Defense Modulation.

Parasites represent a diverse and widely distributed group of pathogens that cause diseases with significant global health implications. The interaction between parasite and host is characterized by a high degree of complexity, with both parties continuously adapting to changes in the other. The successful host invasion is largely attributable to the evasion strategies employed by parasites to ensure their survival in immunocompetent individuals. In turn, the host's defense mechanisms utilize a variety of structures and processes, ranging from primary barriers to the most sophisticated ones, to counter the parasite attack. Acting as an early line of defense, the immune system includes a variety of cell types that are capable of recognizing, destroying, and eliminating infectious agents. Undoubtedly, the orchestration of first-line innate immune responses but also adaptive immunity processes during infection depends to a large extent on the involvement of tissue-resident mast cells (MCs). MCs are capable of supporting immune reactions to parasites through a broad spectrum of processes, including degranulation, synthesis and release of cytokines/chemokines and other mediators, and the generation of reactive oxygen species (ROS). They may also be involved in immune cell recruitment, phagocytosis, and the provision of extracellular DNA traps. Despite the well documented association of MCs with antibacterial and antiviral defense, their role in host protection against parasites remains incompletely identified. This article provides an overview of the engagement of MCs in host defense mechanisms developed during parasitic infections. Furthermore, it considers the impact of parasites or parasite-derived molecules on the various aspects of MC activity.