Treatment with novel AP-1 and NF-κB inhibitors restores the colonic endocrine cells to normal levels in rats with DSS-induced colitis

Ligilactobacillus Salivarius LCK11 Prevents Obesity by Promoting PYY Secretion to Inhibit Appetite and Regulating Gut Microbiota in C57BL/6J Mice

SCOPE

Obesity is a common disease worldwide and there is an urgent need for strategies to preventing obesity.

METHODS AND RESULTS

The anti-obesity effect and mechanism of Ligilactobacillus salivarius LCK11 (LCK11) is studied using a C57BL/6J male mouse model in which obesity is induced by a high-fat diet (HFD). Results show that LCK11 can prevent HFD-induced obesity, reflected as inhibited body weight gain, abdominal and liver fat accumulation and dyslipidemia. Analysis of its mechanism shows that on the one hand, LCK11 can inhibit food intake through significantly improving the transcriptional and translational levels of peptide YY (PYY) in the rectum, in addition to the eventual serum PYY level; this is attributed to the activation of the toll-like receptor 2/nuclear factor-κB signaling pathway in enteroendocrine L cells by the peptidoglycan of LCK11. On the other hand, LCK11 supplementation effectively reduces the Firmicutes/Bacteroidetes ratio and shifts the overall structure of the HFD-disrupted gut microbiota toward that of mice fed on a low-fat diet; this also contributes to preventing obesity.

CONCLUSION

LCK11 shows the potential to be used as a novel probiotic for preventing obesity by both promoting PYY secretion to inhibit food intake and regulating gut microbiota.

Inhibition of Cellular and Animal Inflammatory Disease Models by NF-κB Inhibitor DHMEQ

General inflammatory diseases include skin inflammation, rheumatoid arthritis, inflammatory bowel diseases, sepsis, arteriosclerosis, and asthma. Although these diseases have been extensively studied, most of them are still difficult to treat. Meanwhile, NF-κB is a transcription factor promoting the expression of many inflammatory mediators. NF-κB is likely to be involved in the mechanism of most inflammatory diseases. We discovered a specific NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), about 20 years ago by molecular design from a natural product. It directly binds to and inactivates NF-κB components. It has been widely used to suppress cellular and animal inflammatory disease models and was shown to be potent in vivo anti-inflammatory activity without any toxicity. We have prepared ointment of DHMEQ for the treatment of severe skin inflammation. It inhibited inflammatory cytokine expressions and lowered the clinical score in mouse models of atopic dermatitis. Intraperitoneal (IP) administration of DHMEQ ameliorated various disease models of inflammation, such as rheumatoid arthritis, sepsis, and also graft rejection. It has been suggested that inflammatory cells in the peritoneal cavity would be important for most peripheral inflammation. In the present review, we describe the synthesis, mechanism of action, and cellular and in vivo anti-inflammatory activities and discuss the clinical use of DHMEQ for inflammatory diseases.

Versatile Functions of Somatostatin and Somatostatin Receptors in the Gastrointestinal System

Somatostatin (SST) and somatostatin receptors (SSTRs) play an important role in the brain and gastrointestinal (GI) system. SST is produced in various organs and cells, and the inhibitory function of somatostatin-containing cells is involved in a range of physiological functions and pathological modifications. The GI system is the largest endocrine organ for digestion and absorption, SST-endocrine cells and neurons in the GI system are a critical effecter to maintain homeostasis via SSTRs 1-5 and co-receptors, while SST-SSTRs are involved in chemo-sensory, mucus, and hormone secretion, motility, inflammation response, itch, and pain via the autocrine, paracrine, endocrine, and exoendocrine pathways. It is also a power inhibitor for tumor cell proliferation, severe inflammation, and post-operation complications, and is a first-line anti-cancer drug in clinical practice. This mini review focuses on the current function of producing SST endocrine cells and local neurons SST-SSTRs in the GI system, discusses new development prognostic markers, phosphate-specific antibodies, and molecular imaging emerging in diagnostics and therapy, and summarizes the mechanism of the SST family in basic research and clinical practice. Understanding of endocrines and neuroendocrines in SST-SSTRs in GI will provide an insight into advanced medicine in basic and clinical research.

Protective Effects of SIRT6 Overexpression against DSS-Induced Colitis in Mice

Sirtuin 6 (SIRT6), as a NAD + -dependent deacetylase, plays an indispensable role in the regulation of health and physiology. Loss of SIRT6 causes spontaneous colitis in mice and makes intestinal epithelial cells prone to stress. However, whether SIRT6 overexpression increases resistance to colitis remains unknown. Here, in vivo results demonstrated that SIRT6 overexpression attenuates DSS-induced colitis in terms of clinical manifestations, histopathological damage, loss of tight junction function and imbalanced intestinal microenvironment. Additionally, we also found that the activation of NF-κB and c-Jun induced by DSS is diminished by SIRT6 overexpression. Furthermore, SIRT6 may regulate TAK1 to inhibit NF-κB and c-Jun signaling. Thus, our findings highlight the protective effect of SIRT6 on colon, further supporting the perspective that SIRT6 may be a therapeutic target for intestine injury under stress.

Chromogranin-A and its derived peptides and their pharmacological effects during intestinal inflammation

The gastrointestinal tract is the largest endocrine organ that produces a broad range of active peptides. Mucosal changes during inflammation alter the distribution and products of enteroendocrine cells (EECs) that play a role in immune activation and regulation of gut homeostasis by mediating communication between the nervous, endocrine and immune systems. Patients with inflammatory bowel disease (IBD) typically have altered expression of chromogranin (CHG)-A (CHGA), a major soluble protein secreted by EECs that functions as a pro-hormone. CHGA gives rise to several bioactive peptides that have direct or indirect effects on intestinal inflammation. In IBD, CHGA and its derived peptides are correlated with the disease activity. In this review we describe the potential immunomodulatory roles of CHGA and its derived peptides and their clinical relevance during the progression of intestinal inflammation. Targeting CHGA and its derived peptides could be of benefit for the diagnosis and clinical management of IBD patients.

Chromogranin A cell density in the large intestine of Asian and European patients with irritable bowel syndrome

OBJECTIVE

Patients with irritable bowel syndrome (IBS) in Asia show distinctive differences from those in the western world. The gastrointestinal endocrine cells appear to play an important role in the pathophysiology of IBS. The present study aimed at studying the density of chromogranin A (CgA) cells in the large intestine of Thai and Norwegian IBS patients.

METHODS

Thirty Thai IBS patients and 20 control subjects, and 47 Norwegian IBS patients and 20 control subjects were included. A standard colonoscopy was performed in both the patients and controls, and biopsy samples were taken from the colon and the rectum. The biopsy samples were stained with hematoxylin-eosin and immunostained for CgA. The density of CgA cells was determined by computerized image analysis.

RESULTS

In the colon and rectum, the CgA cell densities were far higher in both IBS and healthy Thai subjects than in Norwegians. The colonic CgA cell density was lower in Norwegian IBS patients than in controls, but did not differ between Thai IBS patients and controls. In the rectum, the CgA cell densities in both Thai and Norwegian patients did not differ from those of controls.

CONCLUSIONS

The higher densities of CgA cells in Thai subjects than Norwegians may be explained by a higher exposure to infections at childhood and the development of a broad immune tolerance, by differences in the intestinal microbiota, and/or differing diet habits. The normal CgA cell density in Thai IBS patients in contrast to that of Norwegians may be due to differences in pathophysiology.

Gastrointestinal neuroendocrine peptides/amines in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic recurrent condition whose etiology is unknown, and it includes ulcerative colitis, Crohn’s disease, and microscopic colitis. These three diseases differ in clinical manifestations, courses, and prognoses. IBD reduces the patients’ quality of life and is an economic burden to both the patients and society. Interactions between the gastrointestinal (GI) neuroendocrine peptides/amines (NEPA) and the immune system are believed to play an important role in the pathophysiology of IBD. Moreover, the interaction between GI NEPA and intestinal microbiota appears to play also a pivotal role in the pathophysiology of IBD. This review summarizes the available data on GI NEPA in IBD, and speculates on their possible role in the pathophysiology and the potential use of this information when developing treatments. GI NEPA serotonin, the neuropeptide Y family, and substance P are proinflammatory, while the chromogranin/secretogranin family, vasoactive intestinal peptide, somatostatin, and ghrelin are anti-inflammatory. Several innate and adaptive immune cells express these NEPA and/or have receptors to them. The GI NEPA are affected in patients with IBD and in animal models of human IBD. The GI NEPA are potentially useful for the diagnosis and follow-up of the activity of IBD, and are candidate targets for treatments of this disease.

Abnormal differentiation of stem cells into enteroendocrine cells in rats with DSS-induced colitis

The present study aimed to determine whether there is an association between abnormalities in enteroendocrine cells in dextran sulfate sodium (DSS)-induced colitis and the clonogenic and/or proliferative activities of stem cells. A total of 48 male Wistar rats were divided into four groups. Animals in the control group were provided with normal drinking water, whereas DSS colitis was induced in the remaining three groups. The rats with DSS-induced colitis were randomized into the following three groups: i) DSS group, which received 0.5 ml 0.5% carboxymethyl cellulose (CMC; vehicle); ii) DSS-G group, which was treated with 3-[(dodecylthiocarbonyl)-methyl]-glutarimide at 20 mg/kg body weight in 0.5% CMC; and iii) DSS-Q group, which was treated with dehydroxymethylepoxyquinomicin at 15 mg/kg body weight in 0.5% CMC. Treatments were administered intraperitoneally twice daily for 5 days in all groups. Subsequently, tissue samples from the colon were stained with hematoxylin-eosin, or immunostained for chromogranin A (CgA), Musashi 1 (Msi1), Math-1, neurogenin 3 (Neurog3) and neurogenic differentiation D1 (NeuroD1). The densities of CgA, Msi1-, Math-1-, Neurog3- and NeuroD1-immunoreactive cells were determined. DTCM-G, and DHMEQ ameliorated the inflammation in DSS-induced colitis. The density of CgA-, Neurog3- and NeuroD1-immunoreactive cells was significantly higher in the DSS group compared with in the control group, and the density of CgA cells was correlated with the densities of Neurog3- and NeuroD1-immunoreactive cells. There were no significant differences in the densities of Msi1- and Math-1-immunoreactive cells among the four experimental groups. The elevated densities of enteroendocrine cells detected in DSS-induced colitis may be due to the increased differentiation of early enteroendocrine progenitors during secretory lineage. It is probable that the DSS-induced inflammatory processes trigger certain signaling pathways, which control differentiation of the stem-cell secretory lineage into mature enteroendocrine cells.

Enteroendocrine cells, stem cells and differentiation progenitors in rats with TNBS-induced colitis

Patients with inflammatory bowel disease (IBD), as well as animal models of human IBD have abnormal enteroendocrine cells. The present study aimed to identify the possible mechanisms underlying these abnormalities. For this purpose, 40 male Wistar rats were divided into 4 groups as follows: the control group, the group with trinitrobenzene sulfonic acid (TNBS)-induced colitis with no treatment (TNBS group), the group with TNBS-induced colitis treated with 3-[(dodecylthiocarbonyl)-methyl]-glutarimide (DTCM-G; an activator protein-1 inhibitor) (DTCM-G group), and the group with TNBS-induced colitis treated with dehydroxymethylepoxyquinomicin (DHMEQ; a nuclear factor-κB inhibitor) treatment (DHMEQ group). Three days following the administration of TNBS, the rats were treated as follows: those in the control and TNBS groups received 0.5 ml of the vehicle [0.5% carboxymethyl cellulose (CMC)], those in the DTCM-G group received DTCM-G at 20 mg/kg body weight in 0.5% CMC, and those in the DHMEQ group received DHMEQ at 15 mg/kg body weight in 0.5% CMC. All injections were administered intraperitoneally twice daily for 5 days. The rats were then sacrificed, and tissue samples were taken from the colon. The tissue sections were stained with hemotoxylin-eosin and immunostained for chromogranin A (CgA), serotonin, peptide YY (PYY), oxyntomodulin, pancreatic polypeptide (PP), somatostatin, Musashi1 (Msi1), Math1, Neurogenin3 (Neurog3) and NeuroD1. The staining was quantified using image analysis software. The densities of CgA-, PYY-, PP-, Msi1-, Neurog3- and NeuroD1-positive cells were significantly lower in the TNBS group than those in the control group, while those of serotonin-, oxyntomodulin- and somatostatin-positive cells were significantly higher in the TNBS group than those in the control group. Treatment with either DTCM-G or DHMEQ restored the densities of enteroendocrine cells, stem cells and their progenitors to normal levels. It was thus concluded that the abnormalities in enteroendocrine cells and stem cells and their differentiation progenitors may be caused by certain signaling substances produced under inflammatory processes, resulting in changes in hormone expression in enteroendocrine cells. These substances may also interfere with the colonogenic activity and the differentiation of the stem-cell secretory lineage into mature enteroendocrine cells.