INFLAMMATORY REGULATION OF SKELETAL MUSCLE LIPID ACCUMULATION WITH OBESITY

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0219350
• Project Start Date: Oct 1, 2009
• Project End Date: Sep 30, 2014
• Program Code: [(N/A)]- (N/A)

Recipient Organization
VIRGINIA POLYTECHNIC INSTITUTE
(N/A)
BLACKSBURG,VA 24061

Performing Department
Human Nutrition & Foods

Non Technical Summary
Skeletal muscle lipid accumulation occurs with obesity and contributes to the development of insulin resistance. SCD1 activity is elevated in skeletal muscle of obese humans and contributes to dysregulated fatty acid metabolism . Toll-like receptor signaling and NF-kB activation are involved in fatty acid-induced insulin resistance in skeletal muscle. Preliminary evidence links TLR4 signaling through NF-kB to increased SCD1 transcription and increased cellular lipid accumulation. New preliminary data shows that a high lipid environment induces TLR4 signaling and NF-kB activation in skeletal muscle, which coincides with increased SCD1 protein content. The current proposal will expand on these findings to determine if there is a causal relationship between TLR4/NF-kB pathway and dyregulated lipogenesis and insulin resitance in skeletal muscle. Discerning a causal relationship would be important because pharmacological targeting of upstream regulators of SCD1, such as TLR4 and/or NF-kB, could provide new opportunities for treating obesity-associated insulin resistance.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
702	7010	1010	50%
702	7010	1020	20%
702	7010	1030	20%
702	7010	1040	10%

Knowledge Area
702 - Requirements and Function of Nutrients and Other Food Components;

Subject Of Investigation
7010 - Biological Cell Systems;

Field Of Science
1040 - Molecular biology; 1030 - Cellular biology; 1010 - Nutrition and metabolism; 1020 - Physiology;

Keywords

obesity

skeletal muscle

metabolism

insulin resistance

type 2 diabetes

Goals / Objectives
SPECIFIC AIM: Hypothesis: TLR4 signaling through NF-kB increases SCD1 activity and contributes to free fatty acid-induced skeletal muscle lipid accumulation and insulin resistance in humans. Objective: Use a euglycemic-hyperinsulinemic clamp, in combination with a 6 h lipid/heparin infusion, to determine if the TLR4/NF-kB pathway mediates increased SCD1 activity, skeletal muscle lipid accumulation, and insulin resistance in humans. Rationale: Acute hyperlipidemia causes an increase in intramuscular lipid accumulation and the development of insulin resistance in both animals and humans. This response is associated with reductions in IkB protein content, a marker of increased NF-kB activity. Specific Aim 3 proposes to expand on Aim 2 and to apply a model of acute hyperlipidemia to humans. Six hours of lipid infusion induces skeletal muscle lipid accumulation and insulin resistance in nonobese, healthy humans. This technique, in combination with the hyperinsulinemic-euglycemic clamp, will be used to assess the role of the TLR4 signaling, NF-kB activation, and increased SCD1 activity in acute lipid-induced insulin resistance.

Project Methods
Experimental Strategy. The proposed human studies will be performed at the GCRC at the Wake Forest Medical Center where Jorge Calles, M.D. will supervise all testing procedures. Additionally, either the PI or his post-doctoral fellow will be present at all infusion and hyper-insulinemic-euglycemic clamp procedures for muscle sample procurement and transport to Virginia Tech for processing. Nonobese and obese humans will be studied as part of Aim 3. Twenty nonobese, healthy humans (n=10 male, n=10 female) will be recruited for a randomized cross-over design in which they are studied on two occasions: one for a 6 h lipid infusion followed by a 2 h hyperinsulinemic-euglycemic clamp, and a second for a saline infusion followed by hyperinsulinemic-euglycemic clamp. As a 6 h lipid-infusion has been shown to induce whole-body and skeletal muscle insulin resistance, this model is ideal for studying the role of TLR4/NF-kB and SCD1 in lipid-induced insulin resistance. It is expected that stimulation of TLR4 signaling, NF-kB activation, and SCD1 activity in skeletal muscle will occur in concert with insulin resistance in response to the lipid infusion, which will be absent following the saline infusion. Obese, insulin-resistant humans (n=10 male, n=10 female) will be studied, cross-sectionally, to assess the relationship between TLR4 signaling, NFkB activation, intramuscular lipid accumulation, SCD1 expression/activity, and skeletal muscle and whole-body insulin resistance. As hyperlipidemia is a co-morbidity of the obese insulin-resistant state, it is expected that TLR4 signaling, NF-kB activation, and SCD1 activity in skeletal muscle will be heightened in the skeletal muscle of obese humans compared to corresponding basal levels in nonobese humans.

Progress 10/01/09 to 09/30/14

Outputs
Target Audience: The scientific community that partake in research endeavors associated with obesity, diabetes, and metabolism-based research. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? 4 graduate students particpated in this five year project. How have the results been disseminated to communities of interest? There have been over 25 publications since the inception of this project, and over 15 presentations at scientific meetings. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The highlight of this work is that as little as 5 days of high fat feeding in healthy, human males disrupts the normal metabolic response in skeletal muscle to a meal. Five days of high fat feeding induced metabolic inflexibility in skeletal muscle, which occurs in the absence of insulin resistance. These findings suggest that metabolic inflexibility may be the initiating insult that causes insulin resistance in response to high fat feeding. Metabolic inflexibility occured in concert with activation of pro-inflammatory signaling pathways, e.g., p38-MAPK. Interestingly, metabolic inflexibility was not associated with activation of NF-kB.

Publications

• Type: Journal Articles Status: Published Year Published: 2014 Citation: Anderson, A. S., Roberts, P. C., Frisard, M. I., Hulver, M. W., and Schmelz, E. M. (2014) Ovarian tumor-initiating cells display a flexible metabolism. Experimental cell research 328, 44-57
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Cheng, Z., Schmelz, E. M., Liu, D., and Hulver, M. W. (2014) Targeting mitochondrial alterations to prevent type 2 diabetes-Evidence from studies of dietary redox-active compounds. Molecular nutrition & food research 58, 1739-1749
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Dorenkott, M. R., Griffin, L. E., Goodrich, K. M., Thompson-Witrick, K. A., Fundaro, G., Ye, L., Stevens, J. R., Ali, M., O'Keefe, S. F., Hulver, M. W., and Neilson, A. P. (2014) Oligomeric cocoa procyanidins possess enhanced bioactivity compared to monomeric and polymeric cocoa procyanidins for preventing the development of obesity, insulin resistance, and impaired glucose tolerance during high-fat feeding. Journal of agricultural and food chemistry 62, 2216-2227
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Gao, S., McMillan, R. P., Jacas, J., Zhu, Q., Li, X., Kumar, G. K., Casals, N., Hegardt, F. G., Robbins, P. D., Lopaschuk, G. D., Hulver, M. W., and Butler, A. A. (2014) Regulation of substrate oxidation preferences in muscle by the peptide hormone adropin. Diabetes 63, 3242-3252
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Goodrich, K. M., Dorenkott, M. R., Ye, L., O'Keefe, S. F., Hulver, M. W., and Neilson, A. P. (2014) Dietary Supplementation with Cocoa Flavanols Does Not Alter Colon Tissue Profiles of Native Flavanols and Their Microbial Metabolites Established during Habitual Dietary Exposure in C57BL/6J Mice. Journal of agricultural and food chemistry 62, 11190-11199
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Li, X., Luo, J., Anandh Babu, P. V., Zhang, W., Gilbert, E., Cline, M., McMillan, R., Hulver, M., Alkhalidy, H., Zhen, W., Zhang, H., and Liu, D. (2014) Dietary supplementation of chinese ginseng prevents obesity and metabolic syndrome in high-fat diet-fed mice. Journal of medicinal food 17, 1287-1297
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Scheffler, T. L., Scheffler, J. M., Park, S., Kasten, S. C., Wu, Y., McMillan, R. P., Hulver, M. W., Frisard, M. I., and Gerrard, D. E. (2014) Fiber hypertrophy and increased oxidative capacity can occur simultaneously in pig glycolytic skeletal muscle. American journal of physiology. Cell physiology 306, C354-363
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Zhang, S., Hulver, M. W., McMillan, R. P., Cline, M. A., and Gilbert, E. R. (2014) The pivotal role of pyruvate dehydrogenase kinases in metabolic flexibility. Nutrition & metabolism 11, 10
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Zhang, S., McMillan, R. P., Hulver, M. W., Siegel, P. B., Sumners, L. H., Zhang, W., Cline, M. A., and Gilbert, E. R. (2014) Chickens from lines selected for high and low body weight show differences in fatty acid oxidation efficiency and metabolic flexibility in skeletal muscle and white adipose tissue. International journal of obesity 38, 1374-1382
• Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Boutagy, N., Marinik, E., McMillan, R., Anderson, A., Frisard, M., Davy, B., Rivero, J, Davy, k., Hulver, M. (2014) Angiotensin II rececptor blockade and skeletal muscle metabolism in overwieght and obese adults with elevated blood pressure. Therapeutic Advances in Cardiovascular Disease, (In Press)
• Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Anderson, A., Haynie, K., McMillan, R., Osterberg, K., Boutagy, N., Frisard, M., Davy, B., Davy, K., Hulver, M. (2014) Early skeletal muscle adaptations to short-term high fat diestb in humans prior to changes in insulin sensitivity, Obesity, In Press.
• Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Frisard, M., Wu, Y., McMillan, R., Voelker, K., Wahlberg, K., Anderson, A., Boutagy, N., Resendes, K., Ravussin, E., Hulver, M. (2014) Low levels of lipopolysaccharide modulate mitochondrial oxygen consumption in skelatl muscle. Metabolism, In Press.

Progress 10/01/12 to 09/30/13

Outputs
Target Audience: Scientific Communities Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Three maunscripts are in preparation as a result of this work. What do you plan to do during the next reporting period to accomplish the goals? Short and long-term high fat feeding studies will proceed. New studies have been designed to ascertain possible mechanism(s) by which high fat feeding disrupts metabolism in skeletal muscle, with an emphasis on stress kinases and mitochondrial bioenergetics.

Impacts
What was accomplished under these goals? During the last reporting period, studies were expanded to include short-term (5 days) and long-term (28 days) high fat feeding in healthy humans. The short-term high fat feeding study revealed that as little as 5 days of high fat feeding can dysregulate normal skeletal muscle metabolism in response to a meal. These observations occurred in concert with an elevated inflammatory response in skeletal muscle. These observations have led to the working hypothesis that a heightened inflammatory tone in skeletal muscle adversely impacts normal metabolic reponses in skeletal muscle to nutrient flux. The data has yet to be analyzed for the long-term high fat feeding study.

Publications

• Type: Book Chapters Status: Published Year Published: 2013 Citation: Berryman, D. E. and Hulver, M.W. Cellular and Whole Body Energetics in Biochemical, Physiological, and Molecular Aspects of Human Nutrition, Stipanuk, M.H., and Caudill, M. A., Eds. St. Louis, MO: Elsevier Saunders, 2013, pp. 481-500.
• Type: Book Chapters Status: Published Year Published: 2013 Citation: Stevens, J. and Hulver, M.W. Stearoyl-CoA Desaturase-1 Activity in Skeletal Muscle: Is it Good or Bad? in Stearoyl-CoA Desaturase Genes in Lipid Metabolism, Ntambi, J.M., Ed. New York, NY: Springer, 2013, pp. 103-118.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Marinik, E.L., Frisard, M.I., Hulver, M.W., Davy, B.M, Rivero, J.M., Salva, J.S., and Davy, K.P., Angiotensin II receptor blockade and insulin sensitivity in overweight and obese adults with elevated blood pressure. There Adv Cardiovasc Dis, 7(1):11-20, 2013.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Anderson, A.S., Roberts, P.C., Frisard, M.I., McMillan, R.P., Bown, T.J., Lawless, T.J., Hulver, M.W., and Schmelz, E.M. Metabolic changes during ovarian cancer progression as targets for sphingosine treatment. Exp Cell Res, 319(10):1431-42, 2013.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Hasek, B., Boudreau, A., Shin, J., Fend, D., Hulver, M., Van, N., Laque, A., Stewart, L.K., Stone, K.P., Wanders, D., Ghosh, S., Pessin, J., and Gettys, T.W. Remodeling the integration of lipid metabolism between liver and adipose tissue by dietary methionine restriction in rats. Diabetes, epub ahead of print, June 2013

Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: The current project is studying the effects of high levels of saturated fatty acids on skeletal muscle lipid metabolism. Diets high in saturated fats have been linked to skeletal muscle insulin resistance but the mechanism(s) for this deleterious effect are not known. We have published that activation of TLR4 in skeletal muscle impairs fatty acid oxidation. We have also shown that acute activation of TLR4 with endotoxin impairs mitochondrial function, which is currently in peer review for publication. During the last year, we have completed a study examining the effects of 5 days of high saturated fat feeding on skeletal muscle metabolic flexibility in humans (publication in preparation). We have also expanded our studies to mouse models with skeletal muscle-specific over expression of TLR4 (mTLR4). These studies showed that mTLR4 mice gain more weight and become more glucose intolerant in response to high fat feeding than their wild-type littermates. Additionally, the mTLR4 mice produce more superoxide and possess increased oxidative stress in skeletal muscle than their wild-type littermates. Ongoing projects include longer term (4 weeks) high fat feeding studies in humans and the characterization of a mouse model we have developed with skeletal muscle-specific knockout of TLR4. PARTICIPANTS: Matthew W. Hulver, Collaborators; Madlyn Frisard, Kevin Davy, Brenda Davy, Ryan McMillan, and Research Scientist; Kris Osterberg, Doctoral candidate; Nabil Boutagy. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Change of knowledge: Data generated in my laboratory, as well as others, have shown that a heightened immune response in skeletal muscle deleteriously impacts skeletal muscle metabolic flexibility. Previous work has shown that an immune response in skeletal muscle causes muscle wasting, but to date, our data is the first to show dysregulated metabolism. Moreover, we have shown in this reporting year that over-expression of TLR4 in skeletal muscle leads to oxidative stress; and that acute high fat feeding in humans induces an inflammatory response in skeletal muscle, which is associated with skeletal muscle metabolic inflexibility

Publications

• M. Carrer, N. Liu, C.E. Grueter, A.H. Williams, M.I. Frisard, M.W. Hulver, R. Bassl-Duby, and E.N. Olson, Control of mitochondrial metabolism and systemic energy homeostasis by microRNAs 378 and 378*. PNAS, In press. 2012
• Suagee, J.K., Corl, B.A., Hulver, M.W., MCCutheon, L.J., and R.J. Geor. Effects of hyperinsulinemia on glucose and lipid transporter expression in insulin-sensitive horses. Domestic Animal Endocrinology, 40(3):173-81, 2011.
• Suagee, J.K., Corl, B.A., Wearn, J.G., Crisman, M.V., Hulver, M.W., Geor, R.J., and L.J. McCutcheon. Effects of the insulin sensitizing drug, pioglitazone, and endotoxin administration on insulin sensitivity in horses. Journal of Veterinary Internal Medicine, 25(2):356-64, 2011.
• Liu N., Bezprozvannaya S., Shelton J., Wu Y., Frisard M.,I. McMillan R.P., Hulver M.W., Voelker K.A., Grange R., Richardson J., Bassel-Duby, R., Olson E., Mice lacking microRNA 133a develop dynamin 2-dependent centronuclear myopathy. Journal of Clinical Investigation, 121(8):3258-6, 2011.
• Suagee, J.K., Corl, B.A., Hulver, M.W., Crisman, L., McCutcheon, J., and R.J. Geor. Effects of acute hyperinsulinemia on inflammatory proteins in horses. Veterinary Immunology and Immunopathology, 142(3-4):141-6, 2011.
• Potteiger, J.P., Claytor, R.P., Hulver, M.W., Hughes, M.R., Carper, M.J., and Thyfault, J.P. Resistance exercise and aerobic exercise when paired with dietary energy restriction both reduce the clinical components of metabolic syndrome in previously physically inactive males. European Journal of Applied Physiology. 112(6):2035-44, 2011.
• Wearn, J.G., Suagee, J.K, Crisman, M.V., Corl, B.A., Hulver, M.W., Hodgson,D.R., Geor, R.J., and McCutcheon, L.J. Effects of the insulin sensitizing drug, pioglitazone, and lipopolysaccharide administration on markers of systymic inflammation and clinical parameters in horses. Veterinary Immunology and Immunopathology, 145(1-2):42-9, 2012.
• Yang, Z., Hulver, M.W., McMillan, R. P., Cai, L., Kershaw, E. E., Yu, L., Xue, B., and Shi, H. Regulation of leptin and insulin action by muscle suppressor of cytokine signaling 3 (SOCS3). PLoS ONE, In press. 2012,
• G. Murali, G.L. Milne, C.D. Webb, A.B. Stewart, R.P. McMillan, B.C. Lyle, M.W. Hulver, and S. Viswanthan, Fish oil and indomethacin in combination potently reduce dyslipidemia and hepatic steatosis in LDLR-/- mice. J Lipid Res In press, 2012
• KM Goodrich, G Fundaro, LE Griffin, A Grant, MW Hulver, MA Ponder, AP Neilson, Dietary grape seed extract increases colonic expression of gut tight junction protein occludin and reduces fecal calprotectin in healthy Wistar Furth rats, Nutr Res In press, 2012.
• Y. Jiao, S.K. George, Q. Zhaoq, M.W. Hulver, S.M. Hutson, C.E., Bishop, and B. Lu, Mex3c mutation reduces adiposity and increase energy expenditure, Moll Cell Biol, In press, 2012

Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: OUTPUTS: The current project is studying the effects of high levels of saturated fatty acids on skeletal muscle lipid metabolism. Diets high in saturated fats have been linked to skeletal muscle insulin resistance but the mechanism(s) for this deleterious effect are not known. Preliminary evidence from our lab suggests that high levels saturated fatty acids result in the activation of pathways associated with an innate immune response in skeletal muscle. More specifically, the toll-like receptor 4 (TLR4) pathway is activated and as a result, the skeletal muscle's ability to oxidize fatty acids as an energy source becomes impaired. To date, these observations have been made in cell culture and mouse studies. Additional animal studies are underway to better understand mechanisms by which activation of an immune response in skeletal muscle modulates metabolism. The current project is expanding these studies to humans. Subject recruitment, data collection, and data analysis continued during the reporting year and to date we have completed twelve subjects. Data continue to support that fatty oxidation in skeletal muscle is reduced in response to 5 days of a high saturated fat diet and this response is significantly correlated with activation of the nuclear factor kappa beta signaling pathway, which is a marker is a heightened immune response. Moreover, we have obtained preliminary data to suggest that the normal adaptation to a single high fat meal is disrupted following 5 days of high fat feeding. Recruitment is underway to confirm these findings in additional research participants. PARTICIPANTS: Matthew W. Hulver, PI; Madlyn Frisard, Co-investigator; Kevin Davy, Co-investigator; Kevin Voelker, Post doctoral trainee; Ryan McMilllan, Post doctoral trainee; Kimberly Haynie, Doctoral Candidate; Kristin Wahlber, M.S. student and; Kris Osterberg, Doctoral candidate. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Change of knowledge: As a result of the work in my laboratory as well as collaborations with other laboratories, we have shown that a heightened immune response in skeletal muscle deleteriously impacts fatty acid metabolism. Previous work has shown that an immune response in skeletal muscle causes muscle wasting but to date, our data is the first to show dysregulated metabolism. Moreover, we have shown in this reporting year that the inflammatory mediated effects on fatty acid metabolism in skeletal muscle are dependent of the production reactive oxygen species.

Publications

• Civitarese, A.E., MacLean, P.S., Carling, S., Kerr-Bayles, L., McMillan, R.P., Pierce, A., Becker T.C., Moro, C., Finlayson, J., Lefort, N., Newgard, C.B., Mandarino, L., Cefalu, W., Walder, K., Collier, G.R., Hulver, M.W., Smith, S.R., Ravussin, E. 2010. Regulation of skeletal muscle oxidative capacity and insulin signaling by the mitochondrial rhomboid protease PARL, Cell Metabolism, 11(5):412-26.
• Bell, J.A., Reed, M., Consitt, L.A., Martin, O., Haynie, K., Hulver, M.W., Muoio, D.M., and Dohm, G.L. 2010. Lipid Partitioning, Incomplete Fatty Acid Oxidation, and Insulin Signal Transduction in Primary Human Muscle Cells: Effects of Severe Obesity, Fatty Acid Incubation, and Fatty Acid Translocase/CD36 Overexpression. Journal of Clinical Endocrinology and Metabolism, 95(7):340-10.
• Consitt, L.A., Bell, J.A., Koves, T.R., Muoio, D.M., Haynie, K., Hulver, M.W., Dohm, G.L., and Houmard, J.A. 2010. PGC-1α overexpression increases lipid oxidation in myocytes from extremely obese individuals, Diabetes, 59(6):1407-15.
• Sparks, L.M., Moro, C., Ukropcova, B., Bajpeyi, S., Civitarese, A.E., Hulver, M.W., Thoresen, G.H., Rustan, A.C., and Smith S.R. 2011. Remodeling lipid metabolism and insulin responsiveness in human primary myotubes. PLoS One, 6(7).
• Flack, K.D., Day, K.P., Hulver, M.W., Winett, R.A., and Davy, B. 2011. Aging, Aging, Resistance Training, and Diabetes Prevention Journal of Aging Research, In Press.
• Frisard, M.I., Wu, Y., Voelker, K., McMillan, R.P., Wahlberg, Twig, G., Ravussin, E., Shirihai, O, and Hulver, M.W. 2011. Toll-like receptor 4 modulates skeletal muscle mitochondrial function in free radical dependent manner. In Review.
• McMillan, R.P., Frisard, M.I., Voelker, K., and Hulver, M.W. 2011. A high-saturated lipid environment sensitizes the toll-like receptor 4 pathway in skeletal muscle. In Review.
• Yang Z., Hulver MW. McMillan R., Kershaw E., Liqing Y., Xue B., and Shi H. Regulation of leptin and insulin signaling by muscle suppressor of cytokine signaling 3 (SOCS3). In Review. 2011.
• Suagee, J.K., Corl, B.A., Hulver, M.W., MCCutheon, L.J., and R.J. Geor. 2011. Effects of hyperinsulinemia on glucose and lipid transporter expression in insulin-sensitive horses. Domestic Animal Endocrinology, In Press.
• Suagee, J.K., Corl, B.A., Wearn, J.G., Crisman, M.V., Hulver, M.W., Geor, R.J., and L.J. McCutcheon. 2011. Effects of the insulin sensitizing drug, pioglitazone, and endotoxin administration on insulin sensitivity in horses. Journal of Veterinary Internal Medicine, In Press.
• Dynamin 2-dependent centronulcear myopathy in mice lacking microRN 133a. Liu N., Bezprozvannaya S., Shelton J., Wu Y., Frisard M.,I. McMillan R.P., Hulver M.W., Voelker K.A., Grange R., Richardson J., Bassel-Duby, R., Olson E. 2011. Journal of Clinical Investigation, In Press.
• Suagee, J.K., Corl, B.A., Hulver, M.W., Crisman, L., McCutcheon, J., and R.J. Geor. 2011. Effects of acute hyperinsulinemia on inflammatory proteins in horses. Veterinary Immunology and Immunopathology, In Press.
• Potteiger, J.P., Claytor, R.P., Hulver, M.W., Hughes, M.R., Carper, M.J., and Thyfault, J.P. 2011. Resistance exercise and aerobic exercise when paired with dietary energy restriction both reduce the clinical components of metabolic syndrome in previously physically inactive males. European Journal of Applied Physiology. In press.

Progress 10/01/09 to 09/30/10

Outputs
OUTPUTS: The current project is studying the effects of high levels of saturated fatty acids on skeletal muscle lipid metabolism. Diets high in saturated fats have been linked to skeletal muscle insulin resistance but the mechanism(s) for this deleterious effect are not known. Preliminary evidence from our lab suggests that high levels saturated fatty acids result in the activation of pathways associated with an innate immune response in skeletal muscle. More specifically, the toll-like receptor 4 (TLR4) pathway is activated and as a result, the skeletal muscle's ability to oxidize fatty acids as an energy source becomes impaired. To date, these observations have been made in cell culture and mouse studies. Additional animal studies are underway to better understand mechanisms by which activation of an immune response in skeletal muscle modulates metabolism. The current project is expanding these studies to humans. The project was initiated during the reporting year and to date we have completed seven subjects. Preliminary evidence suggests that fatty oxidation in skeletal muscle is reduced in response to 5 days of a high saturated fat diet and this response is significantly correlated with activation of the nuclear factor kappa beta signaling pathway, which is a marker is a heightened immune response. Recruitment is underway to confirm these findings in additional research participants. PARTICIPANTS: Matthew W. Hulver, PI; Madlyn Frisard, Co-investigator; Kevin Davy, Co-investigator; Kevin Voelker, Post doctoral trainee; Ryan McMilllan, Post doctoral trainee; Kimberly Haynie, Doctoral Candidate; Kristin Wahlber, M.S. student and; Kris Osterberg, Doctoral candidate. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Change of knowledge: As a result of the work in my laboratory as well as collaborations with other laboratories, we have shown that a heightened immune response in skeletal muscle deleteriously impacts fatty acid metabolism. Previous work has shown that an immune response in skeletal muscle causes muscle wasting but to date, our data is the first to show dysregulated metabolism. This has resulted in two manuscripts (one in publication and one in review).

Publications

• Frisard, M.I., McMillan, R.P., Marchand, J., Wahlberg, K., Wu, Y., Voekler, K., Heilbronn, L., Haynie, K., Muoio, B., Li, L., and Hulver, M.W. (2010). Toll-like receptor 4 modulates skeletal muscle substrate metabolism, American Journal of Physiology- Metabolism and Endocrinology, 298(5). (Accepted)
• Frisard, M.I., Wu, Y., Voelker, K., McMillan, R.P., Wahlberg, Twig, G., Ravussin, E., Shirihai, O, and Hulver, M.W. (2010). Toll-like receptor 4 modulates skeletal muscle mitochondrial function in free radical dependent manner. Diabetes. (Pending)