HHS Public Access Author manuscript Author Manuscript
Int Innov. Author manuscript; available in PMC 2016 May 10. Published in final edited form as: Int Innov. 2011 ; 2011(1): 91–93.
Multi Vitamin E: E-lusive E-ffects Abstract Investigations into vitamin E’s anti-inflammatory effects must be more comprehensive: Dr Joan Cook-Mills explains how their research could redefine medical perceptions and shed new light on previous studies
Author Manuscript
Firstly, can you provide an overview of the aims and focus of your research?
Author Manuscript
Our aims are to examine signals in vascular cells for the regulation of inflammatory cell recruitment from the blood into tissues. During inflammation, receptors are induced on the endothelial cells lining blood vessels; these receptors activate signals necessary for ‘recruiting’ inflammatory cells. We have focused our research on signals generated by the receptor vascular cell adhesion molecule-1 (VCAM-1), which regulates recruitment of inflammatory cells across endothelial cells in several diseases, including allergy/asthma, cardiovascular diseases, and multiple sclerosis. As we have shown VCAM-1 activates signals in endothelial cells through oxidation of enzymes, we have focused on regulation of oxidation by the antioxidant vitamin E. Existing in many isoforms, the most abundant forms of vitamin E in tissues are α-tocopherol and γ-tocopherol. Therefore, we have studied regulation of VCAM-1-dependent recruitment of inflammatory cells by purified natural isoforms of vitamin E in animal models of allergic inflammation.
Could you explain how the various forms of vitamin E differ? Where is each likely to be found?
Author Manuscript
Vitamin E, a lipid synthesised by plants, is composed of a chromanol head group and lipid tail. Natural vitamin E consists of four tocopherols (α, β, γ, and δ) and four tocotrienols (α, β, γ, and δ). The tocotrienols differ from the tocopherols by the presence of three double bonds in the lipid tail. The α, β, γ, and δ isoforms differ by the number of methyl groups on the chromanol head group. These forms of vitamin E are acquired from lipids in the diet. The most abundant isoforms in human diet and tissues are α- and γ-tocopherol. Levels of αtocopherol in human plasma are consistent around the world, but γ-tocopherol levels are about six times higher in the U.S., where individuals consume much more γ-tocopherol rich soy oil (vegetable oil). Other dietary oils, such as olive oil and sunflower oil, have low levels of γ-tocopherol. Sunflower oil is relatively rich in α-tocopherol compared to other dietary oils; olive oil contains modest α-tocopherol levels and generally undetectable levels of γtocopherol.
CONTACT: Joan Cook-Mills, PhD, Associate Professor, Allergy/Immunology Division, Northwestern University Feinberg School of Medicine, 240 E Huron, McGaw M304, Chicago, IL 60611, USA, T +1 312-503-0906, [email protected].
et al.
Page 2
Author Manuscript
Why have you chosen to focus on the role of both the α-tocopherol and γtocopherol form of vitamin E in this study? These two forms of tocopherols are the most abundant in diet and mammalian tissues; other forms are very low to nearly undetectable. Furthermore, because of preferential transfer of α-tocopherol in the liver, the tissues contain tenfold higher levels of α-tocopherol than γtocopherol when equal dietary levels of these tocopherols are consumed. Thus, it is most interesting that we found that γ-tocopherol ablates the anti-inflammatory benefit of αtocopherol during allergic responses, even though γ-tocopherol is at a tenfold lower tissue concentration than α-tocopherol.
Could you tell us more about how VCAM-1 functions in allergic and Author Manuscript
infection-induced inflammation in the experiments you have carried out in vivo? What are the advantages of using murine models for your tests (above in vitro, or other animal models)?
Author Manuscript
VCAM-1 is a receptor induced on endothelial cells in inflammatory sites. Endothelial cells line blood vessels and VCAM-1’s function is to bind blood leukocytes, activating VCAM-1 to send signals within the endothelial cells. These signals cause endothelial cells to change shape, opening a passageway for leukocytes to migrate and enter inflamed tissue. Murine models have the advantage of allowing examination of regulatory effects of tocopherols in the complex tissue microenvironment of allergic inflammation, as well as establishing physiological levels of tocopherol isoforms in the tissues. These physiological levels of tocopherol isoforms are then used in in vitro studies to identify mechanisms for regulation of leukocyte interactions with isolated vascular endothelial cells.
Are there any achievements you would like to highlight from the project?
Author Manuscript
The tocopherols have long been studied for their anti-inflammatory properties. However, reports in the basic and clinical research studies indicate seemingly conflicting effects of Vitamin E. Meta-analysis of the data suggests no effect of vitamin E on inflammation. This meta-analysis does not differentiate between different isoforms of vitamin E. We have demonstrated that at physiological concentrations of purified tocopherols, γ-tocopherol is pro-inflammatory, whereas α-tocopherol is anti-inflammatory in vitro and in vivo. Moreover, γ-tocopherol ablates the anti-inflammatory benefit of α-tocopherol because, when these two tocopherols are administered together, they no longer regulate allergic inflammation. Our novel results alter our interpretations of previous reports on α-tocopherol when we consider the contribution of γ-tocopherol inadvertently present in diets or oils used as delivery vehicles. This also changes the interpretation of meta-analysis that demonstrates no effect of α-tocopherol on allergic inflammation. This meta-analysis does not take into consideration the opposing effects of γ-tocopherol on α-tocopherol regulation of inflammation.
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 3
Author Manuscript
Elusive effects Armed with new information on its isoforms, this NIH-NCCAM-funded project could transform the study of vitamin E’s relation to human immunoregulatory responses Seeking health benefits and medical treatments through the appropriate amount – or type – of a vitamin could be far more complex than previous studies suggest. Such is certainly the case with vitamin E: far from a single organic compound, it actually consists of a series of different isoforms - four tocopherols and four tocotrienols. Unlike other vitamins whose deficiency has been defined by a single clear condition – scurvy for vitamin C, or rickets for vitamin D – its significance was recognised relatively late. So there is still much we do not know about the effects of vitamin E’s different forms, especially in conjunction with diet or the interaction between its different isoforms.
Author Manuscript
It is in this area that Dr Joan Cook-Mills, Associate Professor at the Northwestern University Feinberg School of Medicine, is making headway. With a background in biochemistry and a research interest in anti-oxidant regulation of endothelial cell function during recruitment of leukocytes into inflammatory sites during disease, her work may alter future studies and reinterpret those already carried out. Vitamin E comes in four different isoforms – α, β, γ and δ. Previous studies have tended to focus on α-tocopherol, thought to have immunoregulatory effects on inflammatory sites caused by conditions such as asthma and atherosclerosis (hardening of blood vessels). But Cook-Mills has found that, in conjunction with the γ-tocopherol isoform, this effect can be negated – meaning studies where this relationship was unknown could be fundamentally flawed.
Author Manuscript
VCAM-1-DEPENDENT RECRUITMENT During inflammation, the receptor VCAM-1 is induced on the surface of endothelial cells, which line blood vessels. VCAM-1 binds to blood leukocytes and sends signals in the endothelial cells, causing them to change shape and create a passageway for leukocytes to migrate into inflamed tissue. These activation signals operate through the oxidation of enzymes, hence vitamin E’s important role as an antioxidant and, more specifically, the role of its most abundant isoforms in tissues, α-tocopherol and γ-tocopherol. Cook-Mills explains how focusing on this relationship has guided their research: “We have reported novel findings that the receptor VCAM-1 on blood vessels sends signals through low levels of reactive oxygen species for recruitment of inflammatory cells. Regulation of these signals by antioxidants would limit inflammation in diseases including asthma, allergy, and atherosclerosis”.
Author Manuscript
While α-tocopherol has anti-inflammatory effects on allergic inflammation, lesser-studied γtocopherol was surprisingly proinflammatory. The isoforms have opposite functional effects on VCAM-1 signalling and leukocyte recruitment: administered together, vitamin E has no effect. Cook- Mills believes this new information could be a key piece of the puzzle: “Our discovery that α-tocopherol and γ-tocopherol have opposing immunoregulatory functions changes interpretations of seemingly conflicting clinical and basic research on α-tocopherol regulation of inflammation,” she remarks. This could be an indication that past studies did
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 4
Author Manuscript
not have all the necessary information. “In previous reports,” continues Cook-Mills, “presence or absence of γ-tocopherol was not considered during design or data interpretation. When γ-tocopherol’s contribution from diets, supplements and oil vehicles is taken into consideration, it changes interpretations.” Several previous reports have suggested that plasma levels of γ-tocopherol in American and Dutch subjects are two to six times higher than most Europeans and Asians. So seemingly conflicting results may actually be consistent, in light of opposing tocopherol functions. LOST ANTI-INFLAMMATORY EFFECTS
Author Manuscript
These findings could reach out beyond the laboratory into treatments as well as the public perception of vitamin E’s assumed health benefits in diet and supplements. “At physiological levels, purified natural α-tocopherol is anti-inflammatory, but these antiinflammatory effects are lost when mixed with pro-inflammatory tocopherol isoforms or oil vehicles containing natural γ-tocopherol - such as soy oil,” observes Cook-Mills. Consequently, α-tocopherol might only show anti-inflammatory benefit where diet and nutrient supplement are not – as many U.S. diets are - rich in soy oil, or where γ-tocopherol has been added as an anti-oxidant to preserve food. In terms of vitamin supplements, CookMills has no doubt they should be treated with care: “Tocopherols should be at supplemental, not high, levels since the clinical literature cautions that high levels of tocopherols can increase high blood pressure or hemorrhagic stroke”.
Author Manuscript
Work previously carried out has focused on the α-tocopherol isoform in humans (including clinical studies of asthma and atherosclerosis), animal models and cell systems. Cook-Mills’ research has demonstrated opposing regulatory functions of α-tocopherol and γ-tocopherol isoforms during allergic inflammation; her studies also indicate that tocopherol’s effects are only partially reversible using physiological levels of the opposing immunoregulatory tocopherol isoform. If acquired through dietary oils or supplements, substantial vitamin E isoforms may have been present before previous studies began. This is consistent with elevated levels of plasma γ-tocopherol in some countries and with the high prevalence of asthma in countries with elevated γ-tocopherol. INTERNATIONAL PRESENTATION
Author Manuscript
To investigate this immunoregulatory effect properly, murine models were employed to observe the process in the complex tissue microenvironment, establishing physiological levels of tocopherol isoforms. From these in vivo and in vitro studies, using spleen leukocytes from freshly isolated male mice, mechanisms were identified for tocopherol isoform regulation of leukocyte interaction with isolated vascular endothelial cells. In their Northwestern University Feinberg School of Medicine laboratory, Cook-Mills has headed up a team of two postdoctoral fellows and two graduate students working on this project. Indeed, she is ever watchful for more opportunities to expand their collaboration: “Recently, our ongoing research has expanded to include several clinical investigators, as we analyse two patient cohorts for tocopherol isoform-specific regulation of inflammation”. But alongside the research itself, Cook-Mills points out that sharing their findings is also key: “Besides peer reviewed research articles (Journal of Immunology, 182:4395, 2009), we
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 5
Author Manuscript
have presented the studies on tocopherol isoform-specific regulation of allergic inflammation at several national and international conferences,” she enthuses. The team has presented at the International Eosinophil Society Meeting 2009 in Bruges, the American Association of Immunology Meeting 2010 in Baltimore, and the Annual Immunology Conference in Chicago in 2008/9. Their reviews, ‘Isoforms of Vitamin E Differentially Regulate Inflammation’, are published in Endocrine, Metabolic & Immune Disorders - Drug Targets, 2010 and ‘VCAM-1 Expression and Signaling during Disease: Regulation by ROS and Antioxidants’ is published in Antioxidants and Redox Signaling, October 2010. Indeed, this dissemination could be key in connecting their research to those other scientific communities who could help their findings become applied treatments. FUTURE RESEARCH
Author Manuscript
Previous studies that have demonstrated some countries have higher human plasma γtocopherol also suggest they have correspondingly high levels of conditions like allergic asthma. Encouragingly, this project’s research could therefore alter the course of treatment for these countries, as Cook-Mills asserts: “Our studies in animal models are also consistent with human plasma γ-tocopherol levels present in the U.S. affecting the efficacy of αtocopherol supplementation in asthma and cardiovascular disease. However, more studies are needed to demonstrate cause and effect of tocopherols on inflammation in humans”. Their ongoing research includes examination of the associations of plasma α- and γtocopherol levels with lung function, in control and asthmatic patients, and ascertaining whether their pro- and anti-inflammatory effects could be reversible. This could lead to controlled clinical studies in patients with inflammatory diseases where, for the first time, tocopherol isoform supplements and baseline plasma tocopherol isoforms are considered.
Author Manuscript
Future research must consider these factors, Cook-Mills is keen to stress: “For interpretation of future basic research and clinical reports, it is critical these reports include source and purity of tocopherol isoforms,” she says. “As tocopherol suspension in lipid vehicles can vary, it is important to measure and report tocopherol levels in vehicle or diet, as well as tissue and plasma concentrations.” Some studies also indicate effects of synthetic tocopherol acetate and succinate can differ from natural forms: to truly understand vitamin E, we must build into future studies the sum total effect of its various isoforms at work. This, CookMills states, can only lead to further clarity and scientific rigour in understanding its effect in the human body: “Currently, meta-analysis of vitamin E is done on studies with various forms of tocopherols. Since these tocopherols have opposing functions, the conclusion is that tocopherols have little effect whereas, in actuality, there are significant opposing effects of tocopherol isoforms on inflammation”.
Author Manuscript
Acknowledgments FUNDING National Institutes of Health - National Center for Complementary and Alternative Medicine (NIH-NCCAM) American Heart Association
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 6
Author Manuscript
Biography
Author Manuscript
DR JOAN COOK-MILLS is an Associate professor at the Northwestern University Feinberg School of Medicine. She earned her PhD in Biochemistry from Michigan State University, working with a member of the National Academy of Sciences, Dr Pam Fraker. She engaged in postdoctoral research at the University of Illinois in Chicago and has been an Assistant and then Associate Professor at the University of Cincinnati before moving her research group to Northwestern University. She has been interested in antioxidant regulation of endothelial cell function during the recruitment of leukocytes into inflammatory sites during disease.
Author Manuscript Author Manuscript Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 7
Author Manuscript
INTELLIGENCE FORMS OF VITAMIN E HAVE OPPOSING EFFECTS ON INFLAMMATION OBJECTIVES The differential regulation of inflammation by isoforms of vitamin E provide a basis towards designing drugs and diets that more effectively modulate inflammatory pathways and improve health. Ongoing objectives are to determine whether the effects of the tocopherol isoforms on inflammation are reversible, especially the pro-inflammatory functions of gammatocopherol. This is critical for future clinical studies and improvement in health by changing tocopherol isoforms in diets and supplements
Author Manuscript Author Manuscript Author Manuscript Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 8
Author Manuscript Author Manuscript Author Manuscript Author Manuscript
An anti-inflammatory balance for vitamin E isoforms (tocopherols)
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 9
Author Manuscript Author Manuscript Author Manuscript
THE TEAM (From left to right): Michelle Marchese, Christine McCary, Joan Cook-Mills, Hiam Abdala- Valencia, and Sergejs Berdnikovs
Author Manuscript Int Innov. Author manuscript; available in PMC 2016 May 10.
Int Innov. Author manuscript; available in PMC 2016 May 10. Published in final edited form as: Int Innov. 2011 ; 2011(1): 91–93.
Multi Vitamin E: E-lusive E-ffects Abstract Investigations into vitamin E’s anti-inflammatory effects must be more comprehensive: Dr Joan Cook-Mills explains how their research could redefine medical perceptions and shed new light on previous studies
Author Manuscript
Firstly, can you provide an overview of the aims and focus of your research?
Author Manuscript
Our aims are to examine signals in vascular cells for the regulation of inflammatory cell recruitment from the blood into tissues. During inflammation, receptors are induced on the endothelial cells lining blood vessels; these receptors activate signals necessary for ‘recruiting’ inflammatory cells. We have focused our research on signals generated by the receptor vascular cell adhesion molecule-1 (VCAM-1), which regulates recruitment of inflammatory cells across endothelial cells in several diseases, including allergy/asthma, cardiovascular diseases, and multiple sclerosis. As we have shown VCAM-1 activates signals in endothelial cells through oxidation of enzymes, we have focused on regulation of oxidation by the antioxidant vitamin E. Existing in many isoforms, the most abundant forms of vitamin E in tissues are α-tocopherol and γ-tocopherol. Therefore, we have studied regulation of VCAM-1-dependent recruitment of inflammatory cells by purified natural isoforms of vitamin E in animal models of allergic inflammation.
Could you explain how the various forms of vitamin E differ? Where is each likely to be found?
Author Manuscript
Vitamin E, a lipid synthesised by plants, is composed of a chromanol head group and lipid tail. Natural vitamin E consists of four tocopherols (α, β, γ, and δ) and four tocotrienols (α, β, γ, and δ). The tocotrienols differ from the tocopherols by the presence of three double bonds in the lipid tail. The α, β, γ, and δ isoforms differ by the number of methyl groups on the chromanol head group. These forms of vitamin E are acquired from lipids in the diet. The most abundant isoforms in human diet and tissues are α- and γ-tocopherol. Levels of αtocopherol in human plasma are consistent around the world, but γ-tocopherol levels are about six times higher in the U.S., where individuals consume much more γ-tocopherol rich soy oil (vegetable oil). Other dietary oils, such as olive oil and sunflower oil, have low levels of γ-tocopherol. Sunflower oil is relatively rich in α-tocopherol compared to other dietary oils; olive oil contains modest α-tocopherol levels and generally undetectable levels of γtocopherol.
CONTACT: Joan Cook-Mills, PhD, Associate Professor, Allergy/Immunology Division, Northwestern University Feinberg School of Medicine, 240 E Huron, McGaw M304, Chicago, IL 60611, USA, T +1 312-503-0906, [email protected].
et al.
Page 2
Author Manuscript
Why have you chosen to focus on the role of both the α-tocopherol and γtocopherol form of vitamin E in this study? These two forms of tocopherols are the most abundant in diet and mammalian tissues; other forms are very low to nearly undetectable. Furthermore, because of preferential transfer of α-tocopherol in the liver, the tissues contain tenfold higher levels of α-tocopherol than γtocopherol when equal dietary levels of these tocopherols are consumed. Thus, it is most interesting that we found that γ-tocopherol ablates the anti-inflammatory benefit of αtocopherol during allergic responses, even though γ-tocopherol is at a tenfold lower tissue concentration than α-tocopherol.
Could you tell us more about how VCAM-1 functions in allergic and Author Manuscript
infection-induced inflammation in the experiments you have carried out in vivo? What are the advantages of using murine models for your tests (above in vitro, or other animal models)?
Author Manuscript
VCAM-1 is a receptor induced on endothelial cells in inflammatory sites. Endothelial cells line blood vessels and VCAM-1’s function is to bind blood leukocytes, activating VCAM-1 to send signals within the endothelial cells. These signals cause endothelial cells to change shape, opening a passageway for leukocytes to migrate and enter inflamed tissue. Murine models have the advantage of allowing examination of regulatory effects of tocopherols in the complex tissue microenvironment of allergic inflammation, as well as establishing physiological levels of tocopherol isoforms in the tissues. These physiological levels of tocopherol isoforms are then used in in vitro studies to identify mechanisms for regulation of leukocyte interactions with isolated vascular endothelial cells.
Are there any achievements you would like to highlight from the project?
Author Manuscript
The tocopherols have long been studied for their anti-inflammatory properties. However, reports in the basic and clinical research studies indicate seemingly conflicting effects of Vitamin E. Meta-analysis of the data suggests no effect of vitamin E on inflammation. This meta-analysis does not differentiate between different isoforms of vitamin E. We have demonstrated that at physiological concentrations of purified tocopherols, γ-tocopherol is pro-inflammatory, whereas α-tocopherol is anti-inflammatory in vitro and in vivo. Moreover, γ-tocopherol ablates the anti-inflammatory benefit of α-tocopherol because, when these two tocopherols are administered together, they no longer regulate allergic inflammation. Our novel results alter our interpretations of previous reports on α-tocopherol when we consider the contribution of γ-tocopherol inadvertently present in diets or oils used as delivery vehicles. This also changes the interpretation of meta-analysis that demonstrates no effect of α-tocopherol on allergic inflammation. This meta-analysis does not take into consideration the opposing effects of γ-tocopherol on α-tocopherol regulation of inflammation.
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 3
Author Manuscript
Elusive effects Armed with new information on its isoforms, this NIH-NCCAM-funded project could transform the study of vitamin E’s relation to human immunoregulatory responses Seeking health benefits and medical treatments through the appropriate amount – or type – of a vitamin could be far more complex than previous studies suggest. Such is certainly the case with vitamin E: far from a single organic compound, it actually consists of a series of different isoforms - four tocopherols and four tocotrienols. Unlike other vitamins whose deficiency has been defined by a single clear condition – scurvy for vitamin C, or rickets for vitamin D – its significance was recognised relatively late. So there is still much we do not know about the effects of vitamin E’s different forms, especially in conjunction with diet or the interaction between its different isoforms.
Author Manuscript
It is in this area that Dr Joan Cook-Mills, Associate Professor at the Northwestern University Feinberg School of Medicine, is making headway. With a background in biochemistry and a research interest in anti-oxidant regulation of endothelial cell function during recruitment of leukocytes into inflammatory sites during disease, her work may alter future studies and reinterpret those already carried out. Vitamin E comes in four different isoforms – α, β, γ and δ. Previous studies have tended to focus on α-tocopherol, thought to have immunoregulatory effects on inflammatory sites caused by conditions such as asthma and atherosclerosis (hardening of blood vessels). But Cook-Mills has found that, in conjunction with the γ-tocopherol isoform, this effect can be negated – meaning studies where this relationship was unknown could be fundamentally flawed.
Author Manuscript
VCAM-1-DEPENDENT RECRUITMENT During inflammation, the receptor VCAM-1 is induced on the surface of endothelial cells, which line blood vessels. VCAM-1 binds to blood leukocytes and sends signals in the endothelial cells, causing them to change shape and create a passageway for leukocytes to migrate into inflamed tissue. These activation signals operate through the oxidation of enzymes, hence vitamin E’s important role as an antioxidant and, more specifically, the role of its most abundant isoforms in tissues, α-tocopherol and γ-tocopherol. Cook-Mills explains how focusing on this relationship has guided their research: “We have reported novel findings that the receptor VCAM-1 on blood vessels sends signals through low levels of reactive oxygen species for recruitment of inflammatory cells. Regulation of these signals by antioxidants would limit inflammation in diseases including asthma, allergy, and atherosclerosis”.
Author Manuscript
While α-tocopherol has anti-inflammatory effects on allergic inflammation, lesser-studied γtocopherol was surprisingly proinflammatory. The isoforms have opposite functional effects on VCAM-1 signalling and leukocyte recruitment: administered together, vitamin E has no effect. Cook- Mills believes this new information could be a key piece of the puzzle: “Our discovery that α-tocopherol and γ-tocopherol have opposing immunoregulatory functions changes interpretations of seemingly conflicting clinical and basic research on α-tocopherol regulation of inflammation,” she remarks. This could be an indication that past studies did
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 4
Author Manuscript
not have all the necessary information. “In previous reports,” continues Cook-Mills, “presence or absence of γ-tocopherol was not considered during design or data interpretation. When γ-tocopherol’s contribution from diets, supplements and oil vehicles is taken into consideration, it changes interpretations.” Several previous reports have suggested that plasma levels of γ-tocopherol in American and Dutch subjects are two to six times higher than most Europeans and Asians. So seemingly conflicting results may actually be consistent, in light of opposing tocopherol functions. LOST ANTI-INFLAMMATORY EFFECTS
Author Manuscript
These findings could reach out beyond the laboratory into treatments as well as the public perception of vitamin E’s assumed health benefits in diet and supplements. “At physiological levels, purified natural α-tocopherol is anti-inflammatory, but these antiinflammatory effects are lost when mixed with pro-inflammatory tocopherol isoforms or oil vehicles containing natural γ-tocopherol - such as soy oil,” observes Cook-Mills. Consequently, α-tocopherol might only show anti-inflammatory benefit where diet and nutrient supplement are not – as many U.S. diets are - rich in soy oil, or where γ-tocopherol has been added as an anti-oxidant to preserve food. In terms of vitamin supplements, CookMills has no doubt they should be treated with care: “Tocopherols should be at supplemental, not high, levels since the clinical literature cautions that high levels of tocopherols can increase high blood pressure or hemorrhagic stroke”.
Author Manuscript
Work previously carried out has focused on the α-tocopherol isoform in humans (including clinical studies of asthma and atherosclerosis), animal models and cell systems. Cook-Mills’ research has demonstrated opposing regulatory functions of α-tocopherol and γ-tocopherol isoforms during allergic inflammation; her studies also indicate that tocopherol’s effects are only partially reversible using physiological levels of the opposing immunoregulatory tocopherol isoform. If acquired through dietary oils or supplements, substantial vitamin E isoforms may have been present before previous studies began. This is consistent with elevated levels of plasma γ-tocopherol in some countries and with the high prevalence of asthma in countries with elevated γ-tocopherol. INTERNATIONAL PRESENTATION
Author Manuscript
To investigate this immunoregulatory effect properly, murine models were employed to observe the process in the complex tissue microenvironment, establishing physiological levels of tocopherol isoforms. From these in vivo and in vitro studies, using spleen leukocytes from freshly isolated male mice, mechanisms were identified for tocopherol isoform regulation of leukocyte interaction with isolated vascular endothelial cells. In their Northwestern University Feinberg School of Medicine laboratory, Cook-Mills has headed up a team of two postdoctoral fellows and two graduate students working on this project. Indeed, she is ever watchful for more opportunities to expand their collaboration: “Recently, our ongoing research has expanded to include several clinical investigators, as we analyse two patient cohorts for tocopherol isoform-specific regulation of inflammation”. But alongside the research itself, Cook-Mills points out that sharing their findings is also key: “Besides peer reviewed research articles (Journal of Immunology, 182:4395, 2009), we
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 5
Author Manuscript
have presented the studies on tocopherol isoform-specific regulation of allergic inflammation at several national and international conferences,” she enthuses. The team has presented at the International Eosinophil Society Meeting 2009 in Bruges, the American Association of Immunology Meeting 2010 in Baltimore, and the Annual Immunology Conference in Chicago in 2008/9. Their reviews, ‘Isoforms of Vitamin E Differentially Regulate Inflammation’, are published in Endocrine, Metabolic & Immune Disorders - Drug Targets, 2010 and ‘VCAM-1 Expression and Signaling during Disease: Regulation by ROS and Antioxidants’ is published in Antioxidants and Redox Signaling, October 2010. Indeed, this dissemination could be key in connecting their research to those other scientific communities who could help their findings become applied treatments. FUTURE RESEARCH
Author Manuscript
Previous studies that have demonstrated some countries have higher human plasma γtocopherol also suggest they have correspondingly high levels of conditions like allergic asthma. Encouragingly, this project’s research could therefore alter the course of treatment for these countries, as Cook-Mills asserts: “Our studies in animal models are also consistent with human plasma γ-tocopherol levels present in the U.S. affecting the efficacy of αtocopherol supplementation in asthma and cardiovascular disease. However, more studies are needed to demonstrate cause and effect of tocopherols on inflammation in humans”. Their ongoing research includes examination of the associations of plasma α- and γtocopherol levels with lung function, in control and asthmatic patients, and ascertaining whether their pro- and anti-inflammatory effects could be reversible. This could lead to controlled clinical studies in patients with inflammatory diseases where, for the first time, tocopherol isoform supplements and baseline plasma tocopherol isoforms are considered.
Author Manuscript
Future research must consider these factors, Cook-Mills is keen to stress: “For interpretation of future basic research and clinical reports, it is critical these reports include source and purity of tocopherol isoforms,” she says. “As tocopherol suspension in lipid vehicles can vary, it is important to measure and report tocopherol levels in vehicle or diet, as well as tissue and plasma concentrations.” Some studies also indicate effects of synthetic tocopherol acetate and succinate can differ from natural forms: to truly understand vitamin E, we must build into future studies the sum total effect of its various isoforms at work. This, CookMills states, can only lead to further clarity and scientific rigour in understanding its effect in the human body: “Currently, meta-analysis of vitamin E is done on studies with various forms of tocopherols. Since these tocopherols have opposing functions, the conclusion is that tocopherols have little effect whereas, in actuality, there are significant opposing effects of tocopherol isoforms on inflammation”.
Author Manuscript
Acknowledgments FUNDING National Institutes of Health - National Center for Complementary and Alternative Medicine (NIH-NCCAM) American Heart Association
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 6
Author Manuscript
Biography
Author Manuscript
DR JOAN COOK-MILLS is an Associate professor at the Northwestern University Feinberg School of Medicine. She earned her PhD in Biochemistry from Michigan State University, working with a member of the National Academy of Sciences, Dr Pam Fraker. She engaged in postdoctoral research at the University of Illinois in Chicago and has been an Assistant and then Associate Professor at the University of Cincinnati before moving her research group to Northwestern University. She has been interested in antioxidant regulation of endothelial cell function during the recruitment of leukocytes into inflammatory sites during disease.
Author Manuscript Author Manuscript Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 7
Author Manuscript
INTELLIGENCE FORMS OF VITAMIN E HAVE OPPOSING EFFECTS ON INFLAMMATION OBJECTIVES The differential regulation of inflammation by isoforms of vitamin E provide a basis towards designing drugs and diets that more effectively modulate inflammatory pathways and improve health. Ongoing objectives are to determine whether the effects of the tocopherol isoforms on inflammation are reversible, especially the pro-inflammatory functions of gammatocopherol. This is critical for future clinical studies and improvement in health by changing tocopherol isoforms in diets and supplements
Author Manuscript Author Manuscript Author Manuscript Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 8
Author Manuscript Author Manuscript Author Manuscript Author Manuscript
An anti-inflammatory balance for vitamin E isoforms (tocopherols)
Int Innov. Author manuscript; available in PMC 2016 May 10.
et al.
Page 9
Author Manuscript Author Manuscript Author Manuscript
THE TEAM (From left to right): Michelle Marchese, Christine McCary, Joan Cook-Mills, Hiam Abdala- Valencia, and Sergejs Berdnikovs
Author Manuscript Int Innov. Author manuscript; available in PMC 2016 May 10.
