Lipid Droplet, a Key Player in Host-Parasite Interactions

Abstract

Lipid droplets (lipid bodies, LDs) are dynamic organelles that have important roles in regulating lipid metabolism, energy homeostasis, cell signaling, membrane trafficking, and inflammation. LD biogenesis, composition, and functions are highly regulated and may vary according to the stimuli, cell type, activation state, and inflammatory environment. Increased cytoplasmic LDs are frequently observed in leukocytes and other cells in a number of infectious diseases. Accumulating evidence reveals LDs participation in fundamental mechanisms of host-pathogen interactions, including cell signaling and immunity. LDs are sources of eicosanoid production, and may participate in different aspects of innate signaling and antigen presentation. In addition, intracellular pathogens evolved mechanisms to subvert host metabolism and may use host LDs, as ways of immune evasion and nutrients source. Here, we review mechanisms of LDs biogenesis and their contributions to the infection progress, and discuss the latest discoveries on mechanisms and pathways involving LDs roles as regulators of the immune response to protozoan infection.

Fat, fight, and beyond: The multiple roles of lipid droplets in infections and inflammation

“…Furthermore, T. gondii promotes the expression of some triglyceride synthesis genes and lipid transporters, and inhibits the expression of lipolytic genes, especially ATGL, favoring the LD accumulation in the host cell . Several parasites lost the ability to synthesize all lipids essential for their survival, requiring the supply of lipids from the host cell, mainly cholesterol . For several protozoan parasites, they rely on host LDs and their lipolytic enzymatic activities to survive and proliferate .…”

“…gondii and L. donovani infections in mice, the roles of the interaction between Irgm3 and LDs in the elimination of the pathogen remain uncertain. It has been suggested that this interaction may be related to blockade of recruitment of LDs by the parasite or even participation of this system in antigen (Ag) presentation . Furthermore, it remains uncertain whether LD recruitment favors parasite survival or a host cell defense mechanism (Fig.…”

“…15,180 The accumulation of LDs in infected cells has been reported for several parasites, such as Trypanosoma cruzi, 135,183 Leishmania amazonensis, 184 Leishmania major, 185 Leishmania infantum, 186 Plasmodium chabaudi, 187 Neospora caninum, 61 and Toxoplasma gondii. 29 During parasite infection, LDs are usually associated with sustaining successful parasite replication within the PV 102,182 (Fig. 3).…”

“…61 Several parasites lost the ability to synthesize all lipids essential for their survival, requiring the supply of lipids from the host cell, mainly cholesterol. 182 For several protozoan parasites, they rely on host LDs and their lipolytic enzymatic activities to survive and proliferate. 47,61 LDs are frequently observed around and within the PV.…”

“…It has been suggested that this interaction may be related to blockade of recruitment of LDs by the parasite or even participation of this system in antigen (Ag) presentation. 11,182 Furthermore, it remains uncertain whether LD recruitment favors parasite survival or a host cell defense mechanism ( Fig. 3).…”