The immune system consists of cells, tissues, organs, etc. that work as a team to fight off illness, infections and other invaders. When an unsafe substance enters the body, the immune system comes to the fore and launches an attack. Olfaction or the sense of smell is a sense through which odors are perceived and functions in detecting danger, pheromones etc. Researchers from various fields of biology, such as behavior ecology, neuroscience, developmental biology, immunology etc., are trying to understand the connection between the olfactory system and the immune system. Previous studies have reported that sense of smell can regulate immune reactions and certain scents can reduce the effects of stress on immune reactions. Thus, it is important and fascinating to study and understand the relation between sense of smell and immune system at different levels.
Stem cells have potential to develop into many different types of cells and acts as a repair system for the body. The Metabolism and Development (MAD) lab at inStem is focused on identifying signals that regulate the development and maintenance of stem cells. The group is interested in learning about how the metabolic condition of progenitors (early descendants of stem cells) and immune cells influences outcomes during development, maintenance, and maturation. The lab uses fruit fly as a model organism to identify metabolic signals and associated sensing systems in order to determine the important chemicals required for metabolism, sensors, and pathways in blood cell development.
Reactive Oxygen Species (ROS) are highly reactive chemicals formed as a byproduct during metabolism of Oxygen. ROS as a signaling molecule play and important role in blood cell development and maintenance, as reported in both invertebrates and vertebrates. In a recent study, MAD lab led by Dr. Tina Mukherjee looked into the metabolic processes that allow immune progenitor cells to regulate their ROS levels. The study described the use of a molecule required for metabolism playing a critical role in the metabolic balance and growth control of blood progenitor cells. The interesting findings from the study concluded that the sense of smell regulates blood progenitor cells and lymph gland development in fruit flies.
The results of the study depicted that blood progenitor cells of fruit fly larvae, which reside in a specialized organ known as the lymph gland, use TCA to generate ROS. The researchers discovered that conditions that cause an increase in progenitor ROS have a negative effect on lymph gland growth. Intriguingly, fruit fly larvae rely on their sense of smell and GABA molecule to moderate blood progenitor ROS. In fruit flies, GABA metabolism via PDK activation maintains TCA activity and blood progenitor ROS balance, as well as normal lymph gland growth. As a result, animals that cannot smell are unable to maintain TCA activity and ROS balance, resulting in lymph gland developmental defects.
Olfaction-derived systemic GABA in lymph gland ROS balance and growth control
Overall, this research highlights the significance of animal odor sensing and the GABA molecule in the regulation of ROS and blood cell development control. The findings by Dr. Mukherjee and her group suggest that the olfactory system plays a very important developmental role in the regulation of immune progenitor cells and development of lymph gland. The relevance of these research findings to the development of blood cells in higher animals will be an intriguing aspect to investigate.