David N. McMurray

Research Interests

Malnutrition and tuberculosis (TB) combine to cause extensive morbidity and mortality in the developing world. Nutritional status may be an important determinant of disease outcome, as well as influencing the response to vaccination or antibiotic therapy. We have developed an excellent model of chronic, moderate protein deficiency in the guinea pig. Protein-deprived guinea pigs exhibit many of the metabolic and clinical hallmarks of kwashiorkor in humans. Recently, we have addressed the effect of dietary n-3 polyunsaturated fatty acids (PUFA) on resistance to TB in guinea pig and mouse models. In many papers published over the past 30 years, with continual funding from NIH, we have dissected the detrimental impact of diet on mechanisms of vaccine-induced resistance of guinea pigs to pulmonary tuberculosis.

In order to study the macrophage-lymphocyte interaction, including cytokine cross-talk, in the guinea pig model of tuberculosis, we have obtained cDNA clones of several guinea pig chemokine and cytokine genes through collaboration with Dr. Teizo Yoshimura at the NCI. These include RANTES, IL-8, MCP-1, IL1β, TNFα, IFNγ, TGFβ, and IL-4. Probes for these and other important cytokines (e.g., IL-12p40, IL-10, iNOS) have been prepared and mRNA levels for these genes have been quantified in guinea pig cells stimulated in vitro by real-time RT-PCR assays. Laser capture microdissection (LCM) studies have revealed the effect of vaccination on cytokine mRNA profiles directly in guinea pig pulmonary TB granulomas. In addition, the development of prokaryotic and eukaryotic gene expression systems have allowed us to produce sufficient quantities of some of the recombinant guinea pig proteins to alter cellular functions in vivo and in vitro, and to raise neutralizing antibodies to block cytokine function. These reagents are being used to assess the role of chemokines and cytokines in vaccine-induced immunity to pulmonary tuberculosis in the guinea pig.

The overall goal of the current funding period (2005-2011) of my NIH grant is to elucidate the mechanisms by which diet and vaccination influence the protective immune responses to low-dose, pulmonary infection of guinea pigs with virulent Mycobacterium tuberculosis. The specific aims are: (1) To elucidate the    mechanisms by which vaccination promotes the accumulation of a protective cellular response in the lungs of guinea pigs; (2) To compare the cellular and cytokine responses of primary and secondary pulmonary granulomas in vaccinated and non-vaccinated guinea pigs following pulmonary challenge with virulent M tuberculosis; (3) To interpret the cytokine cross-talk between immune lymphocyes and infected macrophages which results in the control of mycobacterial accumulation; and (4) To elucidate the mechanisms by which diets enriched in n-3 PUFA impair innate and vaccine-induced resistance to pulmonary tuberculosis.

A second major NIH-sponsored research focus for the laboratory is a collaborative project with Dr. Robert Chapkin in the Department of Nutrition and Food Science. We have spent nearly 20 years elucidating the fundamental mechanisms by which dietary n-3 PUFA exert their anti-inflammatory properties. We study diet-induced alterations in CD4+ T lymphocyte activation in mice fed diets enriched in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Short-term dietary supplementation with highly purified EPA and DHA can modulate membrane lipid composition and certain functional and transmembrane signaling responses of purified mouse CD4+ T lymphocytes. Dietary DHA suppresses mitogen- and antigen-induced T-cell proliferation by inhibiting IL-2 secretion, and these events are accompanied by alterations in the membrane composition of, and protein translocation into, T cell lipid rafts. Changes in raft composition, in turn, affects the function of the immunological synapse (IS) with antigen-presenting cells. We are currently pursuing these studies at the cellular and sub-cellular levels utilizing transgenic (e.g., DO11.10, fat-1) and gene knockout (e.g., IL-10^-/-, PPAR δ^-/-) mouse models. These studies are funded by NIH through 2012.

Graduate students select an independent project within the overall scope of the above research. The students will acquire a strong academic preparation in immunology, microbiology, and cell and molecular biology to assist them in their research goals. The research itself will involve feeding diets and immunizing or infecting experimental animals, perhaps under BSL-3 conditions, and the isolation and culture of various leukocyte populations. Cell culture techniques will include proliferation assays, cytokine assays, phagocytic uptake assays and antimicrobial activity. Cells may be extracted to determine the levels and composition of membrane lipids and second messengers. Polyacrylamide gel electrophoresis, Western and Northern blotting, laser capture microdissection, confocal microscopy, and real-time RT-PCR technologies may be employed to evaluate changes in gene activation and protein function. Students will participate in weekly lab group meetings and a departmental journal club, and present seminars as appropriate. Students will be expected to present their research findings at national meetings (e.g. ASM, EB) and travel to such meetings will be facilitated. Publication of student research in peer-reviewed journals is expected.

Selected Publications

Ly LH, Russell MI, McMurray DN. 2007. Microdissection of the cytokine milieu of pulmonary granulomas from tuberculous guinea pigs. Cell Micro 9: 1127-1136.

Sawant KV, McMurray DN. 2007. Guinea pig neutrophils infected with Mycobacterium tuberculosis produce cytokines which activate alveolar macrophages in non-contact co-cultures. Infect Immun 75: 1870-1877

Ly LH, Russell MI, McMurray DN. 2008. Cytokine profiles in primary and secondary pulmonary granulomas of guinea pigs with tuberculosis. Am J Resp Cell Molec Biol 38: 455-462.

Cho H, de Hass R, Jeevan A, McMurray DN. 2008. Differential activation of alveolar and peritoneal macrophages from BCG-vaccinated guinea pigs. Tuberculosis 88: 307-316.

Chapkin RS, Seo J, McMurray DN, Lupton JR. 2008. Mechanisms by which docosahexaenoic acid and related fatty acids reduce colon cancer risk and inflammatory disorders of the intestine. Chem Phys Lipids 153: 14-23.

Jia Q, Lupton JR. Smith R, Weeks BR, Callaway E, Davidson LA, Kim W, Fan Y-Y, Yang P, Newman RA, Kang JX, McMurray DN, Chapkin RS. 2008. Reduced colitis-associated colon cancer in fat-1 (n-3 fatty acid desaturase) transgenic mice. Cancer Res 68: 3985-3991.

Chapkin RS, McMurray DN, Davidson LA, Patil B, Fan Y-Y, Lupton JR. 2008. Bioactive dietary long-chain fatty acids: Emerging mechanisms of action. Brit J Nutr 100: 1152-1157.

Allen SS, Mackie JT, Russell K, Jeevan A, Skwor TA, McMurray DN. 2008. Altered inflammatory responses following transforming growth factor-β neutralization in experimental guinea pig tuberculous pleurisy. Tuberculosis 88: 430-436.

Ly LH, Barhoumi R, Cho SH, Franzblau SG, McMurray DN. 2008. Vaccination with Bacille Calmette-Guerin promotes mycobacterial control in guinea pig macrophages infected in vivo. J Infect Dis 198: 768-771.

McFarland CT, Fan Y-Y, Chapkin RS, Weeks BR, McMurray DN. 2008. Dietary polyunsaturated fatty acids modulate resistance to Mycobacterium tuberculosis in guinea pigs. J Nutr 138: 2123-2128.

Kim W, Fan Y-Y, Barhoumi R, Smith R, McMurray DN, Chapkin RS. 2008. n-3 polyunsaturated fatty acids suppress the localization and activation of signaling proteins at the immunological synapse in murine CD4+ T cells by affecting lipid raft formation. J Immunol 181: 6236-6243.

Jeevan A, Bonilla DL, McMurray DN. 2009. Expression of Interferon-γ and tumor necrosis factor-α messenger RNA does not correlate with protection in guinea pigs challenged with virulent Mycobacterium tuberculosis by the respiratory route.Immunol 128: e296-e305

Ly LH, McMurray DN. 2009. The Yin-Yang of TNFα in the guinea pig model of tuberculosis. Indian J Exp Biol 47: 432-439

Ly LH, Jeevan A, McMurray DN. 2009. Neutralization of TNFα alters inflammation in guinea pig tuberculous pleuritis.Microbes Infect 11: 680-688.

Chapkin RS, Kim W, Lupton JR, McMurray DN. 2009. Dietary docosahexaenoic and eicosapentaenoic acid: Emerging mediators of inflammation. Prost Leuk Essen Fatty Acids 81: 187-191.

Bonilla DL, Fan Y-Y, Chapkin RS, McMurray DN. 2010. Transgenic mice enriched in omega-3 fatty acids are more susceptible to pulmonary tuberculosis: impaired resistance to tuberculosis in fat-1 mice. J Infect Dis 201: 399-408.