Getting Started in Immunometabolism
Part Three: Literature Resources for Innate Immunity
Myeloid cells are subjected to highly variable environments invivo and invitro. Integrating environmental and cell-specific factors, the emerging field of Immunometabolism is making new connections between well-known metabolic mechanisms and specific innate immune functions. It is becoming increasingly clear that metabolic processes do more than just provide material support cell functions, but also contain key control points to innate immunity. Here are a few recent reviews and other resources to get you started in exploring Immunometabolism.
Key Control Points - mTOR, HIF, and Oxygen
Macrophage, granulocytes, and DC, primarily use glycolysis for generating energy and metabolites for use (reviewed in). mTOR and HIF-1, well known for their ability to change cell function in response to oxygen and other environmental stimuli, are key regulators of metabolic programs as well as specific myeloid functions. HIF-1a and mTOR activity in myeloid cells have been implicated in disease states such as infection, sepsis, and autoimmunity. Transcription factors such as NF-kB that are central to the cytokine response are linked to these signaling pathways as well.
- mTORC1 is a key controller of metabolic programming, proliferation, migration, polarization, and antigen presentation (reviewed in   )
- Oxygen-sensitive HIF proteins are central in innate immune cell regulation  
- Myeloid cells of the airway system may be suppressed by systemic hypoxia 
- ROS are a critical secondary signal for formation of the NLRP3 inflammasome in response to TLR signaling (reviewed in )
- Low O2 levels due to microbial competition and disrupted vasculature may limit neutrophils recruitment to a wound and affect duration of the response 
- Low O2 pre-conditioning via HIF and glycolysis reduces neutrophil-mediated Staph mortality. 
- HIF-1a is essential for DC maturation (reviewed in )
- Through HIF-1a, in vitro oxygen levels can alter DC LPS-responses, CD80 and CD86 expression, and stimulation of allo T cell responses (reviewed in )
- Low O2 may favor DC migration over recruitment functions ()
Physiologically relevant O2 control in vitro is essential for translatable myeloid studies.
- O'Neill, L.A., R.J. Kishton, and J. Rathmell, A guide to immunometabolism for immunologists. Nat Rev Immunol, 2016. 16(9): p. 553-65.
- Devraj, G., et al., Hypoxia and HIF-1 activation in bacterial infections. Microbes and infection, 2017. 19(3): p. 144-156.
- Lewis, A.J., T.R. Billiar, and M.R. Rosengart, Biology and Metabolism of Sepsis: Innate Immunity, Bioenergetics, and Autophagy. Surgical infections, 2016. 17(3): p. 286-293.
- Deng, W., et al., Hypoxia-inducible factor 1 in autoimmune diseases. Cellular immunology, 2016. 303: p. 7-15.
- Rius, J., et al., NF-&kgr; B links innate immunity to the hypoxic response through transcriptional regulation of HIF-1&agr. Nature, 2008. 453(7196): p. 807-811.
- Huynh, L., et al., Opposing regulation of the late phase TNF response by mTORC1-IL-10 signaling and hypoxia in human macrophages. Scientific Reports, 2016. 6: p. 31959.
- Weichhart, T., M. Hengstschlager, and M. Linke, Regulation of innate immune cell function by mTOR. Nat Rev Immunol, 2015. 15(10): p. 599-614.
- Murray, P.J., J. Rathmell, and E. Pearce, SnapShot: Immunometabolism. Cell Metab, 2015. 22(1): p. 190-190 e1.
- Lin, N. and M.C. Simon, Hypoxia-inducible factors: key regulators of myeloid cells during inflammation. The Journal of Clinical Investigation, 2016. 126(10): p. 3661-3671.
- Zinkernagel, A.S., R.S. Johnson, and V. Nizet, Hypoxia inducible factor (HIF) function in innate immunity and infection. J Mol Med, 2007. 85.
- Polke, M., et al., Hypoxia and the hypoxia-regulated transcription factor HIF-1alpha suppress the host defence of airway epithelial cells. Innate Immun, 2017. 23(4): p. 373-380.
- Abais, J.M., et al., Redox regulation of NLRP3 inflammasomes: ROS as trigger or effector? Antioxid Redox Signal, 2015. 22(13): p. 1111-29.
- Saiko, G., K. Cross, and A. Douplik, Mathematical Model of an Innate Immune Response to Cutaneous Wound in the Presence of Local Hypoxia. Adv Exp Med Biol, 2016. 923: p. 427-433.
- Thompson, A.A.R., et al., Hypoxia determines survival outcomes of bacterial infection through HIF-1α–dependent reprogramming of leukocyte metabolism. Science Immunology, 2017. 2(8).
- Corcoran, S.E. and L.A. O’Neill, HIF1α and metabolic reprogramming in inflammation. The Journal of Clinical Investigation, 2016. 126(10): p. 3699-3707.
- Winning, S. and J. Fandrey, Dendritic Cells under Hypoxia: How Oxygen Shortage Affects the Linkage between Innate and Adaptive Immunity. J Immunol Res, 2016. 2016: p. 5134329.
About the Author
Alicia D Henn, PhD, MBA
Alicia Henn has been the Chief Scientific Officer of BioSpherix, Ltd for two years. Previously, she was a researcher at the Center for Biodefense Immune Modeling in Rochester, NY. Alicia obtained her PhD in molecular pharmacology and cancer therapeutics from Roswell Park Cancer Institute in Buffalo, NY and her MBA from the Simon School at University of Rochester in Rochester, NY.