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Mathematical Modeling Estimates the Impact of Acute Gastroenteritis on the Development of IBS in the U.S.
AGA Abstracts
exogenous application of proteases on neuronal excitability (decrease in rheobase and/or increased number of action potentials discharged at twice the rheobase) were studied. Incubation of neurons with supernatants from diarrhea predominant IBS patients induced hyperexcitability compared to controls (n = 18 cells). Mean action potential discharge increased by > 100% compared to controls (mean = 1.6 ± 0.4 control vs. 4.3 ± 0.9 PI-IBS, n = 11 and 9 cells respectively, p = 0.014). In contrast, the effect of supernatants from constipation predominant IBS patients did not differ from controls. To determine if cysteine proteases may be important mediators in the supernatant, the effects of exogenous cysteine proteases (cathepsin-s 500 nM) were studied and the effect of the cysteine protease inhibitor E-64 (100 μM) was determined. Incubation of neurons in cysteine proteases for 2 hours increased excitability in patch clamp recordings. Action potential discharge increased by more than 100% (mean = 1.5 ± 0.2 control vs. 3.8 ± 0.6 cathepsin-s, n = 12 and 11 respectively, p = 0.002). When enemas containing cathepsin- s (500 nM) were applied rectally for 2 hours, visceromotor reflexes evoked by rectal distentions (0 - 60 mmHg) were significantly increased compared to vehicle enemas (p = 0.039). In patch clamp studies, the increased action potential discharge mediated by the incubation with cysteine proteases was blocked by E-64 (mean = 3.8 ± 0.6 cathepsin-s vs. 1.9 ± 0.4 cathepsin-s plus E-64, n = 11 and 14 cells respectively, p = 0.017). To test the selectivity of this inhibitor, the effects of the serine protease trypsin was studied. Incubation in trypsin (50 nM) for 2 hours also increased excitability but this effect was not blocked by E-64, suggesting E-64 was selective for cysteine proteases. IBS supernatant from diarrhea predominant IBS patients was then incubated with E-64 and compared to supernatant alone. Action potential discharge was decreased ~ 100% by E-64 (p< 0.05) and the rheobase increased 20% (did not reach significance) compared to supernatant alone. These data demonstrate that supernatants from diarrhea-predominant IBS patients increase the intrinsic excitability of colonic DRG neurons. Cysteine proteases appear to be important mediators underlying this effect and could play a role in generating visceral hyperalgesia.
as the initial response contraction and the following receptive relaxation. After meal intake the rectal tone response was evaluated. Results: IBS patients had lower pressure and volume thresholds for defecatory urge, discomfort and pain, higher unpleasantness and pain ratings and larger viscerosomatic referral areas compared with controls (p<0.0001 for all comparisons). After meal intake IBS patients had lower thresholds for defecatory urge (p<0.01), discomfort (p<0.001) and pain (p<0.0001), larger referral areas for pain (p<0.001), and higher intensity ratings for unpleasantness (p<0.001) compared with fasting, which was not the case in healthy controls. In the fasting state 47% of the patients demonstrated rectal hypersensitivity (pain threshold<31mmHg;
Su1975 Genomic Determinants of a Relaxation Response Resiliency Program in Inflammatory Bowel Disease and Irritable Bowel Syndrome Manoj Bhasin, Joshua R. Korzenik, Allison Dassatti, Nicole Hasheminejad, Andrea H. Thurler, Jessica Rosenblum, Leslee Kagan, Gregory Fricchione, Ellen A. Slawsby, BethAnn Norton, Sowmya R. Rao, Herbert Benson, John W. Denninger, Towia A. Libermann, Brad Kuo Background: Stress has been implicated in exacerbations of inflammatory bowel diseases (IBD) and irritable bowel syndrome (IBS). The relaxation response (RR) is a physiological and psychological opposite to the stress response and should potentially counteract stressinduced physiological changes. We previously showed that genomic changes elicited by the RR counterregulate genes induced by stress and inflammation. The aim was to identify and compare genomic determinants of a relaxation response resiliency program (RRRP) in IBD and IBS using transcriptional profiling. Methods: We assessed the peripheral blood gene expression profile of 10 IBD and 9 IBS patients before and after a 10 week RRRP using HT U133+ PM arrayplates (Affymetrix). After normalization using the robust multi-chip analysis (RMA) algorithm, differentially expressed genes were identified using Student t-test. To understand the underlying biological mechanisms associated with RRRP regulated genes and the gene sets with concordant differences between the two groups, we performed functional categories, canonical pathways, interactive network, and Geneset Enrichment Analysis (GSEA). Results: IBS-QOL scores decreased (p=0.03), showing clinical improvement from 39.7 at baseline to 29.3 at week 10. IBD-Q scores increased (p=0.21), suggesting a trend towards clinical improvement from 163.6 at baseline to 185.8 at week 10. Principal component analysis of the baseline data separated IBD from most of the IBS patients. However, IBS samples appear to be more heterogeneous with some of them clustering together with IBD. At baseline, 392 genes (P value <0.01) significantly linked to immunological and inflammatory diseases with NF-κB and TGF-β as focus hubs differentiating IBS from IBD. Transcriptional profiling identified 512 differentially expressed transcripts for IBD and 280 for IBS (P value <0.01) between Pre and Post RRRP training. In IBD, GSEA identified significant (P<0.05, FDR<30%, 500 permutations) upregulation of genesets involved in ribosomal protein activity and serine type endopeptidase inhibitor activity and downregulation of FAS, TNFR1, IL1, apoptosis and TGF-β pathways. Similarly in IBS, cell cycle regulation and chromosome segregation related genesets are significantly upregulated and serine metabolism and muscle contraction genesets are downregulated by RRRP. The regulatory hubs of the most comprehensive interactive network, meaning the genes with highest degrees of interactions, consist of NF-κB, AKT, Insulin and tumor necrosis factor (TNF) for IBD and IBS, and TGFβ1 and PPARG in IBD only and BCL2, CSF1, and MAPK1 in IBS only. Conclusion: Our data provide evidence that a RRRP in IBD and IBS patients elicits specific and consistent gene expression changes. NF-κB emerges as a common focus molecule that may counteract the harmful effects of stress in both IBS and IBD.
Su1978 Pharmacogenetics of the Effects of Colesevelam on Colonic Transit in Irritable Bowel Syndrome With Diarrhea Banny S. Wong, Michael Camilleri, Paula Carlson, Suwebatu Odunsi-Shiyanbade, Sanna McKinzie, Irene A. Busciglio, Duane D. Burton, Alan R. Zinsmeister Background & Aims: Colesevelam (CSV) is a bile acid (BA) sequestrant that delays colonic transit (CT) in diarrhea-predominant irritable bowel syndrome (IBS-D). In prior studies, we showed that genetic variants in Klothoβ (KLB) and fibroblast growth factor receptor 4 (FGFR4), whose protein products are critical to fibroblast growth factor 19 (FGF19)-mediated feedback inhibition of hepatic BA synthesis, significantly influence CT in IBS-D. Our aim was to examine the pharmacogenetics of these 2 genes on CSV's effects on CT. Methods: We conducted a pharmacogenetic analysis of data acquired in a double-blind, randomized study of oral placebo versus CSV 1.875 g twice daily taken for 12 to 14 consecutive days in 24 female IBS-D patients (mean age 42.7 y). CT was measured by validated scintigraphic method using delayed-release capsule to deliver 111In-charcoal particles to the ileocolonic region. The primary endpoints for CT were ascending colon emptying half time (AC t1/2) and geometric center at 24 hours (GC24, a valid measure of overall CT). Genotyping was performed on 4 common, non-synonymous, single nucleotide polymorphisms (SNPs) in KLB (rs17618244) and FGFR4 (rs351855, rs386618, and rs1966265). Minor allele frequencies are >15% for all 4 SNPs. Genomic DNA was isolated from blood using standard methods. TaqMan SNP assay was used for genotyping. Two-way analysis of variance was used to detect differential treatment effects on CT by CSV across genotype groups using a dominant genetic model coding for genotype. Results: All 4 SNPs were in Hardy-Weinberg equilibrium in our subjects. The functional genetic variant, FGFR4 rs351855 (Gly388Arg), was associated with differential CSV treatment effect on AC t1/2 (uncorrected p=0.046) and for GC24 (uncorrected p=0.073). In the rs351855 GA/AA genotype group, CSV significantly delayed CT, with increased AC t1/2 (23.46±3.56 vs 9.95±2.70 hours on placebo, p=0.04) and decreased GC24 (2.28±0.31 vs 3.59±0.56 units on placebo, p=0.05). In contrast, in the rs351855 GG genotype, there was no significant effect of CSV treatment on CT with either AC t1/2 (13.38±2.79 vs 18.50±5.33 hours on placebo, p=0.43) or GC24 (3.49±0.59 vs 3.10±0.40 units on placebo, p=0.56). No significant differential CSV treatment effects were
Su1976 Fasting and Postprandial Rectal Hypersensitivity in IBS Patients Hans Törnblom, Jenny Gunnarsson, Iris Posserud, Magnus Simren Background: Colorectal hypersensitivity is proposed to be one of the key pathophysiological factors in patients with irritable bowel syndrome (IBS). Postprandial worsening of symptoms is common in IBS, and in line with this meal intake exaggerates colorectal sensitivity in IBS (Simren et al Gut 2001; Neurogastroenterol Motil 2007; Clin Gastroenterol Heptol 2007). Aim: To evaluate the prevalence of rectal hypersensitivity before and after meal intake in IBS, and to assess the additional information obtained by adding a meal in the evaluation of rectal sensorimotor function. Methods: We included 369 patients with IBS (age 38±13 (mean±SD) years; 279 females) and 35 healthy controls (age 36±11 years; 27 females). The subjects underwent a rectal barostat study with two distension sequences, one before and one 60 min after a liquid meal (800 kcal; 60% fat). We used isobaric phasic distensions. Sensory thresholds, the perceived intensity of unpleasantness and pain, and the viscerosomatic referral area were determined during the distensions. Besides sensitivity variables, we also assessed static (V/P) and dynamic compliance (ΔV/ΔP) during the distensions, as well
AGA Abstracts
S-524
exogenous application of proteases on neuronal excitability (decrease in rheobase and/or increased number of action potentials discharged at twice the rheobase) were studied. Incubation of neurons with supernatants from diarrhea predominant IBS patients induced hyperexcitability compared to controls (n = 18 cells). Mean action potential discharge increased by > 100% compared to controls (mean = 1.6 ± 0.4 control vs. 4.3 ± 0.9 PI-IBS, n = 11 and 9 cells respectively, p = 0.014). In contrast, the effect of supernatants from constipation predominant IBS patients did not differ from controls. To determine if cysteine proteases may be important mediators in the supernatant, the effects of exogenous cysteine proteases (cathepsin-s 500 nM) were studied and the effect of the cysteine protease inhibitor E-64 (100 μM) was determined. Incubation of neurons in cysteine proteases for 2 hours increased excitability in patch clamp recordings. Action potential discharge increased by more than 100% (mean = 1.5 ± 0.2 control vs. 3.8 ± 0.6 cathepsin-s, n = 12 and 11 respectively, p = 0.002). When enemas containing cathepsin- s (500 nM) were applied rectally for 2 hours, visceromotor reflexes evoked by rectal distentions (0 - 60 mmHg) were significantly increased compared to vehicle enemas (p = 0.039). In patch clamp studies, the increased action potential discharge mediated by the incubation with cysteine proteases was blocked by E-64 (mean = 3.8 ± 0.6 cathepsin-s vs. 1.9 ± 0.4 cathepsin-s plus E-64, n = 11 and 14 cells respectively, p = 0.017). To test the selectivity of this inhibitor, the effects of the serine protease trypsin was studied. Incubation in trypsin (50 nM) for 2 hours also increased excitability but this effect was not blocked by E-64, suggesting E-64 was selective for cysteine proteases. IBS supernatant from diarrhea predominant IBS patients was then incubated with E-64 and compared to supernatant alone. Action potential discharge was decreased ~ 100% by E-64 (p< 0.05) and the rheobase increased 20% (did not reach significance) compared to supernatant alone. These data demonstrate that supernatants from diarrhea-predominant IBS patients increase the intrinsic excitability of colonic DRG neurons. Cysteine proteases appear to be important mediators underlying this effect and could play a role in generating visceral hyperalgesia.
as the initial response contraction and the following receptive relaxation. After meal intake the rectal tone response was evaluated. Results: IBS patients had lower pressure and volume thresholds for defecatory urge, discomfort and pain, higher unpleasantness and pain ratings and larger viscerosomatic referral areas compared with controls (p<0.0001 for all comparisons). After meal intake IBS patients had lower thresholds for defecatory urge (p<0.01), discomfort (p<0.001) and pain (p<0.0001), larger referral areas for pain (p<0.001), and higher intensity ratings for unpleasantness (p<0.001) compared with fasting, which was not the case in healthy controls. In the fasting state 47% of the patients demonstrated rectal hypersensitivity (pain threshold<31mmHg;
Su1975 Genomic Determinants of a Relaxation Response Resiliency Program in Inflammatory Bowel Disease and Irritable Bowel Syndrome Manoj Bhasin, Joshua R. Korzenik, Allison Dassatti, Nicole Hasheminejad, Andrea H. Thurler, Jessica Rosenblum, Leslee Kagan, Gregory Fricchione, Ellen A. Slawsby, BethAnn Norton, Sowmya R. Rao, Herbert Benson, John W. Denninger, Towia A. Libermann, Brad Kuo Background: Stress has been implicated in exacerbations of inflammatory bowel diseases (IBD) and irritable bowel syndrome (IBS). The relaxation response (RR) is a physiological and psychological opposite to the stress response and should potentially counteract stressinduced physiological changes. We previously showed that genomic changes elicited by the RR counterregulate genes induced by stress and inflammation. The aim was to identify and compare genomic determinants of a relaxation response resiliency program (RRRP) in IBD and IBS using transcriptional profiling. Methods: We assessed the peripheral blood gene expression profile of 10 IBD and 9 IBS patients before and after a 10 week RRRP using HT U133+ PM arrayplates (Affymetrix). After normalization using the robust multi-chip analysis (RMA) algorithm, differentially expressed genes were identified using Student t-test. To understand the underlying biological mechanisms associated with RRRP regulated genes and the gene sets with concordant differences between the two groups, we performed functional categories, canonical pathways, interactive network, and Geneset Enrichment Analysis (GSEA). Results: IBS-QOL scores decreased (p=0.03), showing clinical improvement from 39.7 at baseline to 29.3 at week 10. IBD-Q scores increased (p=0.21), suggesting a trend towards clinical improvement from 163.6 at baseline to 185.8 at week 10. Principal component analysis of the baseline data separated IBD from most of the IBS patients. However, IBS samples appear to be more heterogeneous with some of them clustering together with IBD. At baseline, 392 genes (P value <0.01) significantly linked to immunological and inflammatory diseases with NF-κB and TGF-β as focus hubs differentiating IBS from IBD. Transcriptional profiling identified 512 differentially expressed transcripts for IBD and 280 for IBS (P value <0.01) between Pre and Post RRRP training. In IBD, GSEA identified significant (P<0.05, FDR<30%, 500 permutations) upregulation of genesets involved in ribosomal protein activity and serine type endopeptidase inhibitor activity and downregulation of FAS, TNFR1, IL1, apoptosis and TGF-β pathways. Similarly in IBS, cell cycle regulation and chromosome segregation related genesets are significantly upregulated and serine metabolism and muscle contraction genesets are downregulated by RRRP. The regulatory hubs of the most comprehensive interactive network, meaning the genes with highest degrees of interactions, consist of NF-κB, AKT, Insulin and tumor necrosis factor (TNF) for IBD and IBS, and TGFβ1 and PPARG in IBD only and BCL2, CSF1, and MAPK1 in IBS only. Conclusion: Our data provide evidence that a RRRP in IBD and IBS patients elicits specific and consistent gene expression changes. NF-κB emerges as a common focus molecule that may counteract the harmful effects of stress in both IBS and IBD.
Su1978 Pharmacogenetics of the Effects of Colesevelam on Colonic Transit in Irritable Bowel Syndrome With Diarrhea Banny S. Wong, Michael Camilleri, Paula Carlson, Suwebatu Odunsi-Shiyanbade, Sanna McKinzie, Irene A. Busciglio, Duane D. Burton, Alan R. Zinsmeister Background & Aims: Colesevelam (CSV) is a bile acid (BA) sequestrant that delays colonic transit (CT) in diarrhea-predominant irritable bowel syndrome (IBS-D). In prior studies, we showed that genetic variants in Klothoβ (KLB) and fibroblast growth factor receptor 4 (FGFR4), whose protein products are critical to fibroblast growth factor 19 (FGF19)-mediated feedback inhibition of hepatic BA synthesis, significantly influence CT in IBS-D. Our aim was to examine the pharmacogenetics of these 2 genes on CSV's effects on CT. Methods: We conducted a pharmacogenetic analysis of data acquired in a double-blind, randomized study of oral placebo versus CSV 1.875 g twice daily taken for 12 to 14 consecutive days in 24 female IBS-D patients (mean age 42.7 y). CT was measured by validated scintigraphic method using delayed-release capsule to deliver 111In-charcoal particles to the ileocolonic region. The primary endpoints for CT were ascending colon emptying half time (AC t1/2) and geometric center at 24 hours (GC24, a valid measure of overall CT). Genotyping was performed on 4 common, non-synonymous, single nucleotide polymorphisms (SNPs) in KLB (rs17618244) and FGFR4 (rs351855, rs386618, and rs1966265). Minor allele frequencies are >15% for all 4 SNPs. Genomic DNA was isolated from blood using standard methods. TaqMan SNP assay was used for genotyping. Two-way analysis of variance was used to detect differential treatment effects on CT by CSV across genotype groups using a dominant genetic model coding for genotype. Results: All 4 SNPs were in Hardy-Weinberg equilibrium in our subjects. The functional genetic variant, FGFR4 rs351855 (Gly388Arg), was associated with differential CSV treatment effect on AC t1/2 (uncorrected p=0.046) and for GC24 (uncorrected p=0.073). In the rs351855 GA/AA genotype group, CSV significantly delayed CT, with increased AC t1/2 (23.46±3.56 vs 9.95±2.70 hours on placebo, p=0.04) and decreased GC24 (2.28±0.31 vs 3.59±0.56 units on placebo, p=0.05). In contrast, in the rs351855 GG genotype, there was no significant effect of CSV treatment on CT with either AC t1/2 (13.38±2.79 vs 18.50±5.33 hours on placebo, p=0.43) or GC24 (3.49±0.59 vs 3.10±0.40 units on placebo, p=0.56). No significant differential CSV treatment effects were
Su1976 Fasting and Postprandial Rectal Hypersensitivity in IBS Patients Hans Törnblom, Jenny Gunnarsson, Iris Posserud, Magnus Simren Background: Colorectal hypersensitivity is proposed to be one of the key pathophysiological factors in patients with irritable bowel syndrome (IBS). Postprandial worsening of symptoms is common in IBS, and in line with this meal intake exaggerates colorectal sensitivity in IBS (Simren et al Gut 2001; Neurogastroenterol Motil 2007; Clin Gastroenterol Heptol 2007). Aim: To evaluate the prevalence of rectal hypersensitivity before and after meal intake in IBS, and to assess the additional information obtained by adding a meal in the evaluation of rectal sensorimotor function. Methods: We included 369 patients with IBS (age 38±13 (mean±SD) years; 279 females) and 35 healthy controls (age 36±11 years; 27 females). The subjects underwent a rectal barostat study with two distension sequences, one before and one 60 min after a liquid meal (800 kcal; 60% fat). We used isobaric phasic distensions. Sensory thresholds, the perceived intensity of unpleasantness and pain, and the viscerosomatic referral area were determined during the distensions. Besides sensitivity variables, we also assessed static (V/P) and dynamic compliance (ΔV/ΔP) during the distensions, as well
AGA Abstracts
S-524