Introduction
Chronic constipation leads to an increased risk of heart disease, stroke, and kidney disease1). Stimulant laxatives provide quick relief and are preferred by patients and pharmaceutical companies; “sennosides” and “bisacodyl,” are more popular compared with bulk-forming laxatives2). However, with prolonged use, the human body becomes habituated to them. The laxatives induce prostaglandin production3) through immune cell aggregation and local cytokine expression4). Thus, prolonged use of stimulant laxatives leads to inflammation and damages the intestinal nervous plexus, leading to intestinal exhaustion5).
Mesalazine can remove reactive oxygen and inhibit the biosynthesis of cytokines including interleukin (IL)-1β and leukotrieneB4, and hence, is used for treating inflammatory bowel disease6). Concurrent intake of mesalazine and stimulant laxatives might suppress leukotriene and the subsequent adverse inflammatory responses, thus allowing the safe and long-term use of sennosides.
Herein, we observed stool characteristics of animal models and performed pathological analyses of their colon tissue to establish the stable use of mesalazine-adapted stimulant laxatives. Lamina propria mononuclear cells (LPMCs) of the colon were then collected for flow cytometry analysis (FACS) and real-time polymerase chain reaction (PCR).
Aims & Methods
Six-week-old BALB/cAJcl mice were assigned to one of the four groups: control, mesalazine (100 mg/kg), sennosides (4.8 mg/kg), or mesalazine and sennosides combination groups, (n = 8 for each group). Each drug was suspended in 0.5% carboxymethylcellulose (CMC). Doses were administered orally once daily for 21 days. Stool samples were collected on days 0, 7, 14, and 21; looseness and weight of each stool sample were measured. Feces were then freeze-dried and weighed to calculate the water content percentage.
Mice were euthanized after 21 days, and their colons were harvested. Inflammatory cell aggregation was detected on pathological evaluation, which was performed via H&E staining. Composition of the aggregated LPMCs was evaluated via FACS. Real-time PCR was performed to detect cytokine mRNA expression in LPMCs.
Results
No differences in food intake, water consumption, and body weight were observed among the groups during the experimental period. On day 21, the sennosides group exhibited significantly greater stool looseness compared with the control group. Stool looseness was similar in the sennosides and combination groups. Water content percentage in the stool was significantly higher in the sennosides group compared with in the control group, and this increase was not influenced by the addition of mesalazine. Inflammatory cell aggregation was detected in sennosides and combination groups. A drastic increase in the level of killer T cells was revealed in the sennosides group on FACS, and mesalazine administration resulted in restoration to normal composition. Regarding mRNA expression, IL-1β, IL-2, and IFN-γ levels were elevated in the sennosides group, which was alleviated by mesalazine co-administration.
Conclusion
Sennosides is predicted to provoke IL-2 and IFN-γ biosynthesis that induces killer T cell aggregation and subsequent IL-1β production. As the combination group did not show any inflammation, it is assumed that mesalazine prohibits the inflammatory process. These results provide further evidence to indicate that mesalazine can alleviate sennosides-induced inflammation without adversely affecting its efficacy. This finding may promote the effective use of laxatives in patients with chronic constipation.
References
1) Joseph Y Chang, et al. Am J Gastroenterol, 105: 822-832 (2010)
2) Barry L. Werth, et al. J. Clin. Med, 10, 143 (2021)
3) Teruyo Yagi, et al. J. Pharm. Pharmacol, 40: 27-30 (1988)
4) B A van Gorkom, et al. Aliment Pharmacol Ther, 13: 443-452 (1999)
5) John H. Cummings, et al. Gut, 15: 758-766 (1974)
6) Koichi Nakamaru, et al. Folia Pharmacol. Jpn, 104：447-457 (1994)