Molecular signalling during cross talk between gut brain axis regulation and progression of irritable bowel syndrome: A comprehensive review

Irritable bowel syndrome (IBS) is a chronic functional disorder which alters gastrointestinal (GI) functions, thus leading to compromised health status. Pathophysiology of IBS is not fully understood, whereas abnormal gut brain axis (GBA) has been identified as a major etiological factor. Recent studies are suggestive for visceral hyper-sensitivity, altered gut motility and dysfunctional autonomous nervous system as the main clinical abnormalities in IBS patients. Bidirectional signalling interactions among these abnormalities are derived through various exogenous and endogenous factors, such as microbiota population and diversity, microbial metabolites, dietary uptake, and psychological abnormalities. Strategic efforts focused to study these interactions including probiotics, antibiotics and fecal transplantations in normal and germ-free animals are clearly suggestive for the pivotal role of gut microbiota in IBS etiology. Additionally, neurotransmitters act as communication tools between enteric microbiota and brain functions, where serotonin (5-hydroxytryptamine) plays a key role in pathophysiology of IBS. It regulates GI motility, pain sense and inflammatory responses particular to mucosal and brain activity. In the absence of a better understanding of various interconnected crosstalks in GBA, more scientific efforts are required in the search of novel and targeted therapies for the management of IBS. In this review, we have summarized the gut microbial composition, interconnected signalling pathways and their regulators, available therapeutics, and the gaps needed to fill for a better management of IBS.

Modulatory effect of caffeic acid in alleviating diabetes and associated complications

Diabetes mellitus (DM) is one of the most common metabolic disorders characterized by elevated blood glucose levels. Prolonged uncontrolled hyperglycemia often leads to multi-organ damage including diabetic neuropathy, nephropathy, retinopathy, cardiovascular disorders, and diabetic foot ulcers. Excess production of free radicals causing oxidative stress in tissues is often considered to be the primary cause of onset and progression of DM and associated complications. Natural polyphenols can be used to induce or inhibit the expression of antioxidant enzymes such as glutathione peroxidase, heme oxygenase-1, superoxide dismutase, and catalase that are essential in maintaining redox balance, and ameliorate oxidative stress. Caffeic acid (CA) is a polyphenolderived from hydroxycinnamic acid and possesses numerous physiological properties includ-ing antioxidant, anti-inflammatory, anti-atherosclerotic, immune-stimulatory, cardioprotective, antiproliferative, and hepatoprotective activities. CA acts as a regulatory compound affecting numerous biochemical pathways and multiple targets. These include various transcription factors such as nuclear factor-B, tumor necrosis factor-α, interleukin-6, cyclooxygenase-2, and nuclear factor erythroid 2-related factor 2. Therefore, this review summarizes the pharmacological properties, molecular mechanisms, and pharmacokinetic profile of CA in mitigating the adverse effects of DM and associated complications. The bioavailability, drug delivery, and clinical trials of CA have also been discussed.

Modulation of host mitochondrial dynamics during bacterial infection

Mitochondria is a dynamic organelle of the cell that can regulate and maintain cellular ATP level, ROS production, calcium signaling and immune response. In order to retain their shape and distribution, mitochondria go through coordinated cycles of fission and fusion. Further, dysfunctional mitochondria are selectively eliminated from the cell via mitophagy to synchronize mitochondrial quality control and cellular homeostasis. In addition, mitochondria when in close proximity with the endoplasmic reticulum can alter the signaling pathways and some recent findings also reveal a direct correlation between the mitochondrial localization in the cell to the immune response elicited against the invading pathogen. These modulations in the mitochondrial network are collectively termed as 'mitochondrial dynamics'. Diverse bacteria, virus and parasitic pathogens upon infecting a cell can alter the host mitochondrial dynamics in favor of their multiplication and this in turn can be a major determinant of the disease outcome. Pharmacological perturbations in these pathways thus could lead to generation of additional therapeutic opportunities. This review will focus on the pathogenic modulation of the host mitochondrial dynamics, specifically during the bacterial infections and describes how dysregulated mitochondrial dynamics facilitates the pathogen's ability to establish efficient infection.

Abstract P6-02-02: Increased interval cancers after the 2009 U.S. preventive services task force guidelines: A single-center, retrospective analysis

Background: In late 2009, the U.S. Preventive Services Task Force (USPSTF) increased the recommended time between screening mammography from one year to two years. We examined the effect of USPSTF recommendations in an integrated safety-net system whose patients often have intermittent access to care. The purpose of this study was to determine if changes in screening guidelines were associated with stage migration or changes in rate of interval cancers.

Methods: We conducted a retrospective cohort analysis of breast cancer patients diagnosed between 2005-2013 at one safety-net hospital. We abstracted stage at diagnosis, time intervals between screening and diagnostic imaging, as well as BIRADS classification from clinical and administrative billing data. We divided patients into two cohorts: Those diagnosed with breast cancer "pre-2010" (2005 – 2010) and "post-2010" (2011-2013). We compared stage of diagnosis between cohorts using Chi-Square tests. In a subset of patients for whom we had prior screening imaging information, we determined the rate of interval cancers. Interval cancers were defined as patients whose diagnosis occurred within 14 months (pre-2010) or within 26 months (post-2010) of normal screening mammography. Logistic regression was used to determine the unadjusted odds of interval cancer as a function of being post-2010 versus pre-2010.

Results: There were 521 unique, breast cancer patients between 2005-2013,

Distribution of Breast Cancer by Stage Stage 0Stage IStage IIStage IIIStage IVTotal2005-200941816142242492010-20134679824421272

249 in the 'pre-2010' cohort, and 272 in the 'post-2010' cohort. In the 2005-2009 cohort, 32.5% and 24.5% of patients were stage I and Stage II respectively. In 2010-2013, 29.0% and 30% were stage I and stage II, respectively. The difference in stage at diagnosis was not statistically significant (p=0.62). In a subset of 178 patients with available screening imaging data, we determined the rate of interval cancers. Pre-2010, 7.4% (8/108) of patients had an interval cancer. Post-2010, 20% (14/70) patients had an interval cancer. Patients diagnosed post-2010 had three times the odds of having an interval cancer compared to pre-2010 patients (OR = 3.13, 95% CI 1.24-7.91, p=0.01).

Discussion: The USPSTF 2009 recommendation is associated with a statistically significant increase in interval cancers in a safety-net population, but we cannot conclude that this contributes to stage migration in this limited population. Investigation of larger groups is needed to further assess how USPSTF guidelines affect outcomes in underserved populations.

Citation Format: Townsend NT, Everhart RM, Bayliss EA, Jaiswal K. Increased interval cancers after the 2009 U.S. preventive services task force guidelines: A single-center, retrospective analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-02-02.

Bone marrow progenitor cells contribute to esophageal regeneration and metaplasia in a rat model of Barrett's esophagus

Barrett's esophagus develops when refluxed gastric juice injures the esophageal squamous lining and the injury heals through a metaplastic process in which intestinal-type columnar cells replace squamous ones. The progenitor cell that gives rise to Barrett's metaplasia is not known, nor is it known why the condition is predisposed to malignancy. We studied the contribution of bone marrow stem cells to the development of Barrett's esophagus in an animal model. Twenty female rats were given a lethal dose of irradiation followed by tail vein injection of bone marrow cells from male rats. Ten days later, the female rats were randomly assigned to undergo either esophagojejunostomy, a procedure that causes reflux esophagitis with intestinal metaplasia, or a sham operation. The rats were killed at 8 weeks and serial sections of the snap-frozen esophagi were cut and mounted on slides. The first and last sections were used for histological evaluation and the intervening sections were immunostained for cytokeratin to identify epithelial cells and analyzed for Y chromosome by fluorescence in situ hybridization (FISH). Histological evaluation of the esophagi from rats that had esophagojejunostomy revealed ulcerative esophagitis and multiple areas of intestinal metaplasia. FISH analyses showed that some of the squamous epithelial cells and some of the columnar epithelial cells lining the glands of the intestinal metaplasia were positive for Y chromosome. These observations suggest that multi-potential progenitor cells of bone marrow origin contribute to esophageal regeneration and metaplasia in this rat model of Barrett's esophagus.

Effect of age and caloric restriction on bleomycin-chelatable and nonheme iron in different tissues of C57BL/6 mice

The objective of this study was to test the hypothesis that the widely observed age-associated increase in the amounts of macromolecular oxidative damage is due to an elevation in the availability of redox-active iron, that is believed to catalyze the scission of H2O2 to generate the highly reactive hydroxyl radical. Concentrations of bleomycin-chelatable iron and nonheme iron were measured in various tissues and different regions of the brain of mice fed on ad libitum (AL) or a calorically restricted (to 60% of AL) diet at different ages. The concentrations of these two pools of iron varied markedly as a function of tissue, age, and caloric intake. There was no consistent ratio between the amounts of nonheme and the bleomycin-chelatable iron pools across these conditions. Nonheme iron concentration increased with age in the liver, kidney, heart, striatum, hippocampus, midbrain and cerebellum of AL animals, whereas bleomycin-chelatable iron increased significantly with age only in the liver. Amounts of both nonheme and bleomycin-chelatable iron remained unaltered during aging in the cerebral cortex and hindbrain of AL mice. Caloric restriction had no effect on iron concentration in the brain or heart, but caused a marked increase in the concentration of both bleomycin-chelatable and nonheme iron in the liver and the kidney. The results do not support the hypothesis that accumulation of oxidative damage with age, or its attenuation by CR, are associated with corresponding variations in redox-active iron.

Effects of hormones on the number, distribution and degranulation of mast cells in the ovarian complex of mice

The changes in the number and degranulation pattern of mast cells varied with the types of hormonal treatment and ovarian compartment. Luteinizing hormone (LH), follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH) and 17-beta estradiol (E2) treatment caused increase (P < 0.05) in the number of mast cells in the hilum as compared with the controls. Increase (P < 0.05) in the number of mast cells in the whole ovarian complex was observed only following FSH and E2 treatment. All the hormones used in the present study increased the percentage degranulation of mast cells in the hilum. However, only LH, FSH and E2 increased the percentage degranulation of mast cells in other compartments of the ovary (medulla, bursa and cortex). TSH and ACTH failed to cause any increase in the percentage degranulation of mast cells in these compartments. The present findings indicate E2 to be the most potent among the hormones tested in causing degranulation of mast cells in all ovarian compartments.

Effects of cimetidine, H2 receptor antagonist, on follicular and luteal development in the mice

The effects of various doses, duration and frequency of cimetidine treatment on vaginal cycle, ovulation, ovarian histology and follicular kinetics were investigated. In addition, studies were performed to assess the reversibility in ovarian functions following withdrawal of cimetidine treatment. A statistically significant (P < 0.05) decline in ovarian and uterine weights, but not in body and adrenal weights, were observed in females treated with cimetidine four times daily for long-term as compared with the controls. Ovarian and uterine weights recovered to pretreatment levels following withdrawal of the treatment. Cimetidine treatment caused irregularities in the reproductive cyclicity of mice. Cimetidine treatment causes adverse effect on ovarian function depending on the time, duration and frequency of treatment. Treatment for only one day at proestrus induced significant (P < 0.05) decline in ovulatory efficiency. However, administration of cimetidine, four times daily, for either 6 or 14 days caused ovarian dysfunction. The treatment depressed the number of healthy preantral and antral follicles as well as number of healthy corpus luteum (CL) in the ovary. Absence of healthy CL, presence of several atretic late antral follicles and reproductive acyclicity provide evidence for the failure of ovulation in mice treated with cimetidine four times per day for 14 days. Moreover, when cimetidine was administered twice daily, the ovaries also showed newly formed CL. The results, thus, suggest that the effects of cimetidine on ovulation are dependent on dose, duration and frequency of treatment. Blockage of ovulation in long-term cimetidine treated mice could be due to its influence on follicular atresia. Ovulation had occurred in these females after withdrawal of cimetidine treatment.