Bacterial hopanoids: a newly identified potent inducer of monocyte to macrophage differentiation

Monocyte to macrophage differentiation is an extremely essential cellular and immunological process aimed to combat the assault of foreign pathogens as well as this process has immense importance in the maintenance of physiological homeostasis. Differentiated macrophage, serving as specialized phagocytes is an indispensable component of innate immunity. Besides this, being a well-documented antigen-presenting cell (APC) macrophages also function as a key regulator of both humoral and cell-mediated immunity: the two integral components of adaptive immunity. Bacterial hopanoids are a primitive analogous of eukaryotic sterols that are established as a prominent immunomodulator. In this study, we have demonstrated the isolation protocol of neutral lipid fractions from different Gram-negative bacteria, and adopting several analytical approaches we proposed that the extracted lipid fractions may contain hopanoid as an active component. We have delved deeper into the biological effect of these probable hopanoids like compounds. Here, by considering the several structural and functional attributes like altered phenotype, expression of macrophage-specific markers, increased intracellular organelles, acquirement of enhanced phagocytic and inflammatory property, induction of autophagy, etc we have established hopanoids as a potential inducer of monocyte to macrophage differentiation. Thus, our study has unraveled a new immunomodulator present in Gram-negative bacteria and would undoubtedly help to understand the intricacies of host-pathogen interaction in a better and conclusive manner.