Ulcerative colitis is a chronic inflammatory disease that frequently progresses to colon cancer. The tumor-promoting effect of inflammation is now widely recognized and understood. Recent studies have revealed that treatment with nicotine ameliorates colitis in humans and experimental murine models, whereas the effect of nicotine on colitis-associated colonic tumorigenesis remains unclear. In the present study, we examined the effect of nicotine on the development of acute colitis and colitis-associated cancer (CAC). The acute colitis model was induced by treatment with 3% dextran sulfate sodium (DSS) for 7 days, whereas the CAC model was induced by a combination of azoxymethane and repeated DSS treatment. Nicotine and a selective agonist of the α₇-nicotinic acetylcholine receptor (α₇-nAChR) reduced the severity of DSS-induced acute colonic inflammation. In addition, the suppressive effect of nicotine on acute colitis was attenuated by an antagonist of α₇-nAChR. Furthermore, nicotine inhibited the IL-6 production of CD4 T cells in the DSS-induced inflamed colonic mucosa. We found that nicotine significantly reduced the number and size of colonic tumors in mice with CAC. Nicotine markedly inhibited the elevation of TNF-α and IL-6 mRNA as well as phosphorylated signal transducer and activator of transcription (Stat) 3 expression in the colons of the tumor model mice. These results demonstrate that nicotine suppresses acute colitis and colitis-associated tumorigenesis, and this effect may be associated with the activation of α₇-nAChR. Furthermore, it is presumed that nicotine downregulates the expression of inflammatory mediators such as IL-6/Stat3 and TNF-α, thereby reducing the colonic tumorigenesis associated with chronic colitis.

The establishment of new therapeutic strategies for metabolic syndrome is urgently needed because metabolic syndrome, which is characterized by several disorders, such as hypertension, increases the risk of lifestyle-related diseases. One approach is to focus on the pre-disease state, a state with high susceptibility before the disease onset, which is considered as the best period for preventive treatment. In order to detect the pre-disease state, we recently proposed mathematical theory called the dynamical network biomarker (DNB) theory based on the critical transition paradigm. Here, we investigated time-course gene expression profiles of a mouse model of metabolic syndrome using 64 whole-genome microarrays based on the DNB theory, and showed the detection of a pre-disease state before metabolic syndrome defined by characteristic behavior of 147 DNB genes. The results of our study demonstrating the existence of a notable pre-disease state before metabolic syndrome may help to design novel and effective therapeutic strategies for preventing metabolic syndrome, enabling just-in-time preemptive interventions.

The prevalence of food allergy (FA) has increased in developed countries over the past few decades. However, no effective drug therapies are currently available. Therefore, we investigated cholinergic anti-inflammatory pathway as a regulatory system to ameliorate disrupted mucosal immune homeostasis in the gut based on the pathophysiological elucidation of mucosal mast cells (MMCs) in a murine FA model. BALB/c mice sensitized with ovalbumin received repeated oral ovalbumin for the development of FA. FA mice developed severe allergic diarrhea and exhibited enhanced type 2 helper T (Th2) cell immune responses in both systemic immunity and mucosal immunity, along with MMCs hyperplasia in the colon. MMCs were localized primarily in the strategic position of the mucosal epithelium. Furthermore, the allergic symptoms did not develop in p85α disrupted phosphoinositide-3 kinase-deficient mice that lacked mast cells in the gut. Vagal stimulation by 2-deoxy-D-glucose and drug treatment with nicotinic ACh receptor (nAChR) agonists (nicotine and α7 nAChR agonist GTS-21) alleviated the allergic symptoms in the FA mice. Nicotine treatment suppressed MMCs hyperplasia, enhanced MPO and upregulated mRNA expression of Th1 and Th2 cytokines in the FA mice colon. MMCs, which are negatively regulated by α7 nAChRs, were often located in close proximity to cholinergic CGRP-immunoreactive nerve fibers in the FA mice colon. The present results reveal that the cholinergic neuroimmune interaction via α7 nAChRs on MMCs is largely involved in maintaining intestinal immune homeostasis and can be a target for a new therapy against mucosal immune diseases with homeostatic disturbances such as FA.

Clinical chemotherapy frequently causes intestinal mucositis as a side effect, which is accompanied by severe diarrhea. We recently showed that the cytokine-mediated apoptotic pathway might be important for the development of intestinal mucositis induced by 5-fluorouracil (5-FU). Saireito, the traditional Japanese herbal (Kampo) medicine, is widely used to treat diarrhea and various inflammatory diseases in Japan. In the present study, we investigated the effect of saireito on 5-FU-induced intestinal mucositis in mice, especially in relation to apoptosis in the intestinal crypt. Male C57BL/6 mice were given 5-FU (50 mg/kg), i.p. once daily for 6 days. Intestinal mucositis was evaluated histochemically. Saireito (100–1000 mg/kg) was administered p.o. twice daily for 6 days. Repeated 5-FU treatment caused severe intestinal mucositis including morphological damage, which was accompanied by body weight loss and diarrhea. Daily administration of saireito reduced the severity of intestinal mucositis in a dose-dependent manner. Body weight loss and diarrhea during 5-FU treatment were also significantly attenuated by saireito administration. The number of apoptotic and caspase-3-activated cells in the intestinal crypt was increased, and was accompanied by up-regulated tumor necrosis factor (TNF)-α and interleukin (IL)-1β mRNA within 24 h of the first 5-FU injection. However, all of these measures were significantly lower after saireito administration. These results suggest that saireito attenuates 5-FU-induced intestinal mucositis. This action may come from the reduction of apoptosis in the intestinal crypt via suppression of the up-regulation of inflammatory cytokines. Therefore, saireito may be clinically useful for the prevention of intestinal mucositis during cancer chemotherapy.

Lubiprostone, a bicyclic fatty acid derived from prostaglandin E₁, has been used to treat chronic constipation and irritable bowel syndrome, and its mechanism of action has been attributed to the stimulation of intestinal fluid secretion via the activation of the chloride channel protein 2/cystic fibrosis transmembrane regulator (ClC-2/CFTR) chloride channels. We examined the effects of lubiprostone on indomethacin-induced enteropathy and investigated the functional mechanisms involved, including its relationship with the EP4 receptor subtype. Male Sprague-Dawley rats were administered indomethacin (10 mg/kg p.o.) and killed 24 hours later to examine the hemorrhagic lesions that developed in the small intestine. Lubiprostone (0.01–1 mg/kg) was administered orally twice 30 minutes before and 9 h after the indomethacin treatment. Indomethacin markedly damaged the small intestine, accompanied by intestinal hypermotility, a decrease in mucus and fluid secretion, and an increase in enterobacterial invasion as well as the up-regulation of inducible nitric-oxide synthase (iNOS) and tumor necrosis factor α (TNFα) mRNAs. Lubiprostone significantly reduced the severity of these lesions, with the concomitant suppression of the functional changes. The effects of lubiprostone on the intestinal lesions and functional alterations were significantly abrogated by the coadministration of AE3-208 [4-(4-cyano-2-(2-(4-fluoronaphthalen-1-yl)propionylamino)phenyl)butyric acid], a selective EP4 antagonist, but not by CFTR(inh)-172, a CFTR inhibitor. These results suggest that lubiprostone may prevent indomethacin-induced enteropathy via an EP4 receptor-dependent mechanism. This effect may be functionally associated with the inhibition of intestinal hypermotility and increase in mucus/fluid secretion, resulting in the suppression of bacterial invasion and iNOS/TNFα expression, which are major pathogenic events in enteropathy. The direct activation of CFTR/ClC-2 chloride channels is not likely to have contributed to the protective effects of lubiprostone.