In order to perform its role as a guard against disease and infection, it is critical for immune cells to know exactly how to differentiate foreign invaders within the body. Two such mechanisms that enable immune cells to identify foreign proteins are phagocytosis and autophagy. Recent research conducted by scientists at Baylor College of Medicine is helping to better understand how these two mechanisms assist in strengthening the innate arm of immune defenses to prevent diseases and infections.
The results of this research appear online in scientific journal Immunity.
Details of the BCM study:
According to the corresponding author of the study, Dr. N. Tony Eissa, (who is also a professor of Pulmonary medicine at Baylor College of Medicine, and whose work in Lymphangioleiomyomatosis Treatment was previously covered here on BioNews Texas) transcription factors such as Nuclear factor-like 2 play a crucial role in phagocytosis and autophagy.
In order to study the behavior of immune cells and their importance in innate immunity, Eissa and his research colleagues introduced mycobacteria (a class of bacteria that is responsible for causing tuberculosis and pneumonia in immuno-compromised patients) in mice with absent autophagy genes. The research team identified that phagocytic cells like macrophages (specialized immune cells and an integral arm of innate immunity) engulfed large amounts of cellular debris and invading pathogens.
Eissa suggested: “They took in so much stuff, and they could not kill it.”
The research team concluded that in mice with absent autophagy genes, the scavenger receptors on macrophages are overexpressed (this is especially true for receptors like macrophage scavenger receptor 1 and macrophage receptor with collagenous structure). Likewise, the Nuclear factor-like 2 also plays an important role in the positive activity of scavenger receptors.
Eissa commented: “We are figuring out how to use this in a clinical infectious disease such as tuberculosis. We want to ensure that autophagy is not deficient and the body doesn’t end up ‘eating” more than it can digest,” adding that, “The big finding in this paper is that autophagy controls both processes.”
About Phagocytosis and Autophagy:
Phagocytosis refers to engulfing cellular debris or invading pathogens by the special contractile action of immune cells (that are designed to serve this purpose). Autophagy is a somewhat similar mechanism with the difference that cellular debris and invading pathogens are degraded by their own. The two mechanisms play an important role in innate immunity and also contribute in the adaptive arm of the immune system.
Other notable researchers who also contributed in the study include Diana L. Bonilla, Youbao Sha, Yi Xu, Abhisek Bhattacharya, and Qian Xiang from Baylor College of Medicine; Arshad Kan and Chinnaswamy Jagannath from The University of Texas Medical School at Houston and Masaaki Komatsu from Tokyo Metropolitan Institute of Medical Science in Japan.
Check out this video from Khan Academy on the role of Phagocytes: