Despite progress in planning and delivery of radiation therapy, treatment of abdominal tumors is dose-limited by the risk of intestinal toxicity (radiation enteropathy). The previous notion that radiation enteropathy develops exclusively as a result of crypt cell death has been supplanted. Instead, it is now widely recognized that many functional and secondary changes contribute to the manifestations of radiation enteropathy. These changes are promising targets for interventions to prevent and/or reduce radiation-induced bowel toxicity. In the intestine, there are important connections between the nervous system and cells of the immune system. Notably, sensory nerves and resident mast cells in the bowel mucosa constitute a functional unit that regulates many physiological and pathological processes through bidirectional interactions. We have shown that crosstalk between intestinal sensory nerves and mast cells substantially regulate the development of radiation enteropathy. The extension of this MERIT award will use validated genetic and phannacologic approaches, coupled with quantitative structural and functional endpoints and molecular methods, to systematically "dissect" the mechanisms by which these neuroimmune interactions modulate the intestinal radiation response. We will 1) examine the role ofthe endocannabinoid system and its relationship to mast cells and sensory neurons in early and delayed radiation enteropathy;2) determine to what extent the kinin- kallikrein system regulates radiation enteropathy development and whether the effects depend on resident mast cells or sensory nerves;and 3) investigate the significance of the sympathetic nervous system in radiation enteropathy. These experiments are based on data generated during the previous funding period and will provide substantial new insight into the basic pathogenesis of the intestinal radiation response. Advancing the understanding ofthe basic mechanisms underlying radiation enteropathy is critical for identifying targets for intervention. This research will thus facilitate development of specific strategies to minimize intestinal radiation toxicity in the clinic and thereby make radiation therapy safer and more effective.

Public Health Relevance

This research focuses on issues that are important to cancer survivors, specifically on making radiation therapy safer and more effective. The goal is to study how interactions between the immune system and nervous system in the bowel affect the development of radiation injury. The studies will generate new insight into how intestinal radiation injury occurs and help develop strategies to minimize such injury.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Method to Extend Research in Time (MERIT) Award (R37)
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Special Emphasis Panel (NSS)
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Wong, Rosemary S
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University of Arkansas for Medical Sciences
Schools of Medicine
Little Rock
United States
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Pathak, Rupak; Wang, Junru; Garg, Sarita et al. (2016) Recombinant Thrombomodulin (Solulin) Ameliorates Early Intestinal Radiation Toxicity in a Preclinical Rat Model. Radiat Res 186:112-20
Koturbash, Igor; Miousse, Isabelle R; Sridharan, Vijayalakshmi et al. (2016) Radiation-induced changes in DNA methylation of repetitive elements in the mouse heart. Mutat Res 787:43-53
Pathak, Rupak; Bachri, Abdel; Ghosh, Sanchita P et al. (2016) The Vitamin E Analog Gamma-Tocotrienol (GT3) Suppresses Radiation-Induced Cytogenetic Damage. Pharm Res 33:2117-25
Pathak, Rupak; Cheema, Amrita K; Boca, Simina M et al. (2015) Modulation of Radiation Response by the Tetrahydrobiopterin Pathway. Antioxidants (Basel) 4:68-81
Sridharan, Vijayalakshmi; Tripathi, Preeti; Aykin-Burns, Nukhet et al. (2015) A tocotrienol-enriched formulation protects against radiation-induced changes in cardiac mitochondria without modifying late cardiac function or structure. Radiat Res 183:357-66
Pathak, Rupak; Shao, Lijian; Ghosh, Sanchita P et al. (2015) Thrombomodulin contributes to gamma tocotrienol-mediated lethality protection and hematopoietic cell recovery in irradiated mice. PLoS One 10:e0122511
Pathak, Rupak; Hauer-Jensen, Martin (2015) Particle Beam may have Higher Effectiveness in Treating Chemo-resistant Cancers than Low-LET Photon Beam Therapy. Res Rev J Pharm Pharm Sci 4:1-2
Hauer-Jensen, Martin (2014) Toward development of interleukin-11 as a medical countermeasure for use in radiological/nuclear emergencies. Dig Dis Sci 59:1349-51
Sridharan, Vijayalakshmi; Tripathi, Preeti; Sharma, Sunil et al. (2014) Roles of sensory nerves in the regulation of radiation-induced structural and functional changes in the heart. Int J Radiat Oncol Biol Phys 88:167-74
Hauer-Jensen, Martin; Denham, James W; Andreyev, H Jervoise N (2014) Radiation enteropathy--pathogenesis, treatment and prevention. Nat Rev Gastroenterol Hepatol 11:470-9

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