Lucas Rocha (IOC/Fiocruz)
Lipid droplets are the main organelles of lipid storage and they play an important role in the organism of living beings. Common parasites, such as bacteria, viruses and protozoans, induce and target these structures during their life cycles. Scientists are well aware that lipid droplets support infection by supplying invaders with substrates for their survival or growth. However, studies show that the host’s immune responses have co-evolved with the pathogens, developing countless defense mechanisms.
More recently, researchers have found evidence that lipid droplets participate actively in innate defense. As a result of an international collaboration, the study, which involved researchers of the Immunopharmacology Laboratory of the Oswaldo Cruz Institute (IOC/Fiocruz), was published in the Science magazine.
The research shows that lipid droplets in mammals have protein-based antimicrobial properties. Using light and electronic microscopy, specialists have observed a specific association between organelles and bacteria in macrophages (cells of the immune system), suggesting the existence of mechanisms that facilitate the involvement of antibacterial proteins of the lipid droplets and the bacteria.
According to the results, organelles form a first line of intracellular defense, i.e. they function as molecular switches in innate immune response, responding to danger signals by reprogramming cellular metabolism and triggering protein-mediated antimicrobial mechanisms.