Dietary supplementation with fresh pineapple juice decreases inflammation and colonic neoplasia in IL-10-deficient mice with colitis.

BACKGROUND: Bromelain, a mixture of proteolytic enzymes typically derived from pineapple stem, decreases production of proinflammatory cytokines and leukocyte homing to sites of inflammation. We previously showed that short-term oral treatment with bromelain purified from pineapple stem decreased the severity of colonic inflammation in C57BL/6 Il10(-/-) mice with chronic colitis. Since fresh pineapple fruit contains similar bromelain enzymes but at different proportions, this study aimed to determine whether long-term dietary supplementation with pineapple (supplied as juice) could decrease colon inflammation and neoplasia in Il10(-/-) mice with chronic colitis as compared with bromelain derived from stem. METHODS: Colitis was triggered in Il10(-/-) mice by exposure to the non-steroidal anti-inflammatory drug piroxicam. Mice with colitis were supplemented with fresh vs. boiled pineapple juice or bromelain purified from stem for up to 6 months. RESULTS: Experimental mice readily consumed fresh pineapple juice at a level that generated mean stool proteolytic activities equivalent to 14 mg bromelain purified from stem, while control mice received boiled juice with inactive enzymes. Survival was increased in the group supplemented with fresh rather than boiled juice (P = 0.01). Mice that received fresh juice also had decreased histologic colon inflammation scores and a lower incidence of inflammation-associated colonic neoplasia (35% versus 66%; P < 0.02), with fewer neoplastic lesions/colon (P = 0.05). Flow cytometric analysis of murine splenocytes exposed to fresh pineapple juice in vitro demonstrated proteolytic removal of cell surface molecules that can affect leukocyte trafficking and activation. CONCLUSIONS: These results demonstrate that long-term dietary supplementation with fresh or unpasteurized frozen pineapple juice with proteolytically active bromelain enzymes is safe and decreases inflammation severity and the incidence and multiplicity of inflammation-associated colonic neoplasia in this commonly used murine model of inflammatory bowel disease.

Treatment with oral bromelain decreases colonic inflammation in the IL-10-deficient murine model of inflammatory bowel disease.

Bromelain is a mixture of proteinases derived from pineapple stem that is marketed in health food stores as a "digestive aid". Orally administered bromelain was anecdotally reported to induce clinical and endoscopic remission of ulcerative colitis in two patients whose disease was refractory to multi-agent conventional medical therapy. However, the potential efficacy of bromelain in colitis has not yet been tested rigorously in either animals or humans. In this study, the clinical and histologic severity of inflammatory bowel disease (IBD) was determined in IL-10-/- mice treated orally with bromelain in vivo. Daily treatment with oral bromelain beginning at age 5 weeks decreased the incidence and severity of spontaneous colitis in C57BL/6 IL-10-/- mice. Bromelain also significantly decreased the clinical and histologic severity of colonic inflammation when administered to piroxicam-exposed IL-10-/- mice with established colitis. Proteolytically active bromelain was required for anti-inflammatory effects in vivo. Adverse effects of dermatitis, hair loss, and weight loss due to mucositis were rare, dose related, and were not seen in wild-type mice treated orally with up to 1000 mg bromelain/kg/day for 18 weeks. Although the exact mechanisms by which exogenous proteinases affect bowel inflammation have not yet been determined, the results justify additional studies of this complementary biologically based approach to treatment of IBD.

Proteinase activity and stability of natural bromelain preparations.

Bromelain is a complex mixture of proteinases typically derived from pineapple stem. Similar proteinases are also present in pineapple fruit. Beneficial therapeutic effects of bromelain have been suggested or proven in several human inflammatory diseases and animal models of inflammation, including arthritis and inflammatory bowel disease. However, it is not clear how each of the proteinases within bromelain contributes to its anti-inflammatory effects in vivo. Previous in vivo studies using bromelain have been limited by the lack of assays to control for potential differences in the composition and proteolytic activity of this naturally derived proteinase mixture. In this study, we present model substrate assays and assays for cleavage of bromelain-sensitive cell surface molecules can be used to assess the activity of constituent proteinases within bromelain without the need for biochemical separation of individual components. Commercially available chemical and nutraceutical preparations of bromelain contain predominately stem bromelain. In contrast, the proteinase activity of pineapple fruit reflects its composition of fruit bromelain>ananain approximately stem bromelain. Concentrated bromelain solutions (>50 mg/ml) are more resistant to spontaneous inactivation of their proteolytic activity than are dilute solutions, with the proteinase stability in the order of stem bromelain>fruit bromelain approximately ananain. The proteolytic activity of concentrated bromelain solutions remains relatively stable for at least 1 week at room temperature, with minimal inactivation by multiple freeze-thaw cycles or exposure to the digestive enzyme trypsin. The relative stability of concentrated versus dilute bromelain solutions to inactivation under physiologically relevant conditions suggests that delivery of bromelain as a concentrated bolus would be the preferred method to maximize its proteolytic activity in vivo.