Uptake of Carboxyfluorenscein-Containing Liposomes by Peyer's Patch and Non-Peyer's Patch Tissue of the Rat Intestine.

Studies have shown that stress in soldiers caused by caloric and sleep deprivation coupled with performance anxiety can markedly suppress immune function. This study was designed to test the possibility of oral targeting of liposomes containing immune-enhancing cargos to the Peyers patch follicles of the small intestine. The mucosal immune system is the bodys primary defense against the entry of infectious agents from the intestinal lumen, and Peyers patches PP are the specific lymphoid follicles located along the small intestine. This report contains the results of three studies on rats orally intubated with immune system-targeted liposomes stabilized against gastrointestinal stresses and containing a fluorescent marker, 56-carboxyfluorescein CF. In the study showing the greatest uptake, one hour after intubation, saline wash showed that 40 of liposomes fed had remained intact in the gut. In this study, total liposome CF uptake per rat was 0.12 of dose, three times that of free CF. In the 45 cm intestinal segment with the most active uptake, specific uptake of liposomal contents in PP was 0.470 nmolcm2, compared to non-Peyers patch NP of 1.64 nmollcm2. The specific uptake of liposomal contents in PP was 3.76 times that previously reported Tomizawa, et al., although lipid uptakes were similar. This result is partly because we achieved a 4.5 fold greater cargo loading of our liposomes. These uptakes are adequate for amplifying compounds like antigens and hormones but seem insufficient for targeting immune-enhancing nutrients. Chronic rather than single dose administration and more highly loaded liposomes or latex microspheres may improve uptakes.