Introducing ...

A member of the International Scientific Advisory Panel -- Yoshimi Shibata, Ph.D.

When David Jackson, DC; Matthew McCoy, DC; and Robert Blanks, PhD founded Research & Clinical Science (RCS), they realized that the credibility and validity of the program would rely in great part on the quality of researchers chosen to analyze the data collected by chiropractors around the world.

They sought out a world‑class group of respected scientists with unimpeachable credentials and proven expertise in health care research. The result of their efforts was the RCS International Scientific Advisory Panel, a multi‑disciplinary group charged with overseeing the collection of, and analyzing, data compiled on hundreds of thousands of volunteers and chiropractic patients across the globe.

Each month during this special series, The Chiropractic Journal profiles one member of this prestigious panel.

Yoshimi Shibata, Ph.D.

As we advance our understanding of the biology of chiropractic, we will need to rely more and more on content experts from many different fields. Consider the following case scenario.

Every day, a healthy person generates tens of millions of dead cells, together accounting for on average 0.5% of all the cells in the body. The immune system and more specifically the innate immune system is tasked with recognizing dying or abnormal cells, enveloping and drawing them into the cytoplasm of cells called macrophages (phagocytosis) and systematically digesting the protein fragments for recycling. Healthy individuals can eliminate a wide range of mild pathogens in this fashion through activation of the "innate immune system." The innate immunity system is what we are born with and it is nonspecific; all antigens are attacked more or less equally.

 Unfortunately, the "modern lifestyle" keeps many individuals in various degrees of immunocompromise from aging, stressful lifestyles, viruses, chronic illness, immune system illnesses (especially AIDS), drugs and trauma (including surgery). An immunocompromised state impairs the effectiveness of the immune system leaving the body vulnerable to various viral, bacterial, or fungal opportunistic infections.

This month's featured scientist is Yoshimi Shibata, Ph.D., Associate Professor, Department of Biomedical Science, Florida Atlantic University. Dr. Shibata is an immunologist who has focused his research on tissue macrophage biology. These cells are essential for the proper function of the innate immune system. The origin of tissue macrophages from monocytes, their cell cycle regulation and ability to recognize live properly functioning cells from dying cells is the area of Dr. Shibata's research.

Dr. Shibata was born and raised in Japan. He completed his Bachelor of Science degree in biology from Yamagata University, and then conducted PhD work in the Department of Bacteriology, at Tohoku University School of Medicine, Sendai, Japan. His research during these seven years focused on bacteriology, immunology and tumor cell biology. During this time, he had the distinction of working with one of the world foremost authorities in virology, Dr. Nakao Ishida. His mentor is credited with, among many other research accomplishments, the discovery of the Sendai virus.

The Sendai virus is a strain of parainfluenza viruses that, unlike the influenza viruses, are relatively weak pathogens in humans (except in immune compromised babies or the elderly). On the other hand, the Sendai virus is particularly devastating in rodents. Dr. Shibata's mentor was the first investigator to create the experimental cell fusion using Sendai virus to destroy the membranes of adjacent cells thereby allowing them to fuse. This process was an important break‑through and was a necessary first‑step to creating genetic manipulations in hybridoma cells. Dr. Ishida is credited with having trained more than 250 professors. Dr. Shibata is one of these distinguished individuals who have gone onto prominent positions in Universities all over the world.

In 1983, Dr. Shibata moved to the United States to work with Dr. Alvin Volkman in the Department of Pathology, East Carolina University School of Medicine, Greenville NC. Over the next five years, he worked closely with Dr. Volkman to examine the mechanism of tissue macrophage production. These cells are derived from monocytes, which are circulating stem cells that are drawn to sites of inflammation in the body through a process known as chemotaxis. Monocytes accumulate at sites of inflammation and transform into tissue macrophages which gobble up the dying cells in the region of inflammation.

A severe side‑effect of macrophage accumulation is their role in triggering a full‑blown inflammatory response. Body trauma will cause local release of chemical attractants, a signaling of monocytes (and another immune‑related cell the neutrophil) that are then drawn to the site usually within about 24 hours. Trauma is required to produce tissue macrophages. There is a small production of these cells in the absence of trauma, but with trauma their numbers grow by orders of magnitude as demonstrated by their research.

Dr. Shibata received his first faculty appointments at the East Carolina University School of Medicine in the Departments of Pathology (1989‑94), Biology (1994‑95), Medicine (1995‑99) and Physiology (1999‑2003). He then assumed his current position at FAU in 2003.

The research during his early faculty years began to slowly shift from experimental pathology and bacteriology to immunology and the role of tissue macrophages. His early work was sponsored by a total of $1.9 million in extramural funding from the National Institutes of Health, private and state grants. Dr. Shibata's current work, which has brought in an additional $1.8 million in grants from the NIH and Department of Defense, examines 1) The shift in immune response (TH1 to TH2) in atherogenesis, and 2) the benefits of oral administration of a type of shellfish chitin for down‑regulation of allergic responses in asthma.

At this midpoint in his career, he is well‑respected by his peers as a leading authority in the field of macrophage signaling. He has published an impressive total of 52 peer‑reviewed publications and has trained 17 postdoctoral, graduate, and medical fellows in his laboratory.

Dr. Shibata's research has had a profound impact on clinical immunology and may help our understanding of the benefits of chiropractic care on the immune system. From a general perspective, many experts view tissue macrophages as a homogeneous population derived from monocytes. However, Dr. Shibata's research has shown that these specialized cells are a very heterogeneous population; lung macrophages (alveolar macrophages) inhabit the lung, liver macrophages (Kupffer cells) inhabit the liver, etc. and one population does not substitute for the other.

His research examines the general hypothesis that disease specificity, i.e., which organ is attacked by the disease process, is dictated by the inflammatory cycle and the tissue specific uniqueness of macrophages. This specificity could help to account for the secondary osteodegenerative changes in the spine and other bones following local trauma.

Dr. Shibata's research interest in allergic asthma, resulting from excessive response by the immune system, examines specific abnormality with the monocytes producing lung macrophages triggering a local allergic reaction that severely restricts the airway passages. Asthma is one of the most significant chronic diseases of children. Much of the treatment cost stems from hospitalizations and emergency room visits to treat acute episodes. Dr. Shibata has demonstrated that a naturally occurring polymer from shellfish (chitin) can reduce the allergic response in mice to specific allergens (i.e., reduced serum levels of immunoglobulin E and eosinophils in the lungs). He hopes that they can proceed to Phase I clinical trials for use of chitin in treatment of childhood asthma.

Dr. Shibata's cutting‑edge research highlights the important health consequences of what is now termed the "chiropractic lifestyle," namely, the need for regular care, for controlling stress in ones life, proper diet and exercise and understanding the serious health consequences over the indiscriminate use of antibiotics and antibacterial agents such as soaps and detergents. Individuals can become immunocompromised by poor lifestyle‑related issues. Preventative approaches including adequate exercise, balanced diet, stress reduction and effective long‑term wellness strategies consistent with the "chiropractic lifestyle" are the best personal strategies for improving immune function and health.

Finally, exciting new research demonstrates that low‑level exposure to bacteria and other infectious agents is required to maintain a normal function of tissue macrophage system and hence a healthy immune system. Antibiotic therapy and the use of antibacterial soaps block the necessary exposure of "friendly" bacteria to the macrophages and therefore one gets a deleterious effect on the innate immune system. There is a need for large controlled studies on individuals who have not been exposed to antibiotics and other immunocompromising drugs.

Dr. Shibata looks forward to assisting in the design and implementation of future studies that will examine the direct influence of chiropractic care on tissue macrophage targeting and overall immune status.