Evolutionary Medicine Provides Insight into the Chronic Inflammatory State Note Rheumatologists at the 2013 ACR/ARHP Annual Meeting

SAN DIEGO—In an elegant and engaging presentation that used concepts from evolutionary medicine to provide novel insights into the pathophysiology of chronic inflammatory diseases, Rainer H. Straub, MD, professor of medicine in the lab of experimental rheumatology and neuroendocrine immunology in the department of internal medicine, division of rheumatology, at University Hospital in Regensburg, Germany, honored the memory of Philip S. Hench, MD, during his delivery of the 2013 Hench Lecture at the at the 2013 ACR/ARHP Annual Meeting. [Editor’s Note: This session was recorded and is available via ACR SessionSelect at www.rheumatology.org.] He showed how the scientific mind works through a hypothesis to arrive at some theoretical possibilities on the mysterious workings of the human body in chronic inflammation.

“In a thoughtful and integrative approach, Dr. Straub advanced the hypothesis that the consequences to the body of chronic inflammatory disease result from prolonged energy requirements of an activated immune system,” said Eric Matteson, MD, chair of the department of rheumatology and professor of medicine at the Mayo Clinic in Rochester, Minn., who moderated the session. “By integrating new insights with studies of metabolism, neuroendocrinology, and immunology, the new model explains the sometimes baffling symptomatology of autoimmune disease.”

What does the hypothesis or new model proposed by Dr. Straub contribute to an understanding of the pathophysiology of chronic inflammatory diseases? The following are some of the steps he walked participants through to explain this new model.

Etiology of Chronic Inflammatory Diseases: Systemic Response

Dr. Straub introduced first the idea of a systemic response as a potential etiological factor in chronic inflammatory diseases (CIDs). Although classic etiological factors of CIDs focus on local inflammation (e.g., the immune system), with the underlying understanding that the dangerous molecules involved in local inflammation remain local and don’t get into the body’s system, Dr. Straub said that inflammatory factors can spill over to the central nervous system or to endocrine glands either through cytokines, such as interleukin (IL) 6 in circulation, or via sensory nerve fibers and activate the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis while shutting down other pathways (e.g., gonadal axis). He provided examples to show that there is crosstalk between local inflammation in tissue and the central nervous system and endocrine organs, and that this crosstalk has influence but is relatively nonspecific (i.e., it is observed in many CIDs).

In answering why there is a systemic response, he focused on the high level of energy consumed when the immune system is activated, indicating that inflammation needs a lot of energy-rich fuels. Regulation of energy, he said, depends on two super systems in the body—the brain and muscles that consume energy during the day and the immune system that consumes energy primarily at night.