Status of Gene Methylation and Polymorphism in Different Courses of Ulcerative Colitis and Their Comparison with Sporadic Colorectal Cancer

BACKGROUND

The objective of this study is to explore the common genetic and epigenetic mechanism of ulcerative colitis (UC) and sporadic colorectal cancer (SCRC) by observing genes methylation level and single nucleotide polymorphisms (SNPs) of different disease courses in UC and SCRC.

METHODS

Two hundred subjects were enrolled, including 40 in the healthy control (HC) group, 50 in the short disease course UC group (SUC), 52 in the long disease course UC group (LUC), and 58 in the SCRC group. Methylation-specific polymerase chain reaction was used to detect the methylation of MINT1 and cyclooxygenase 2 (COX-2) gene. Single nucleotide polymorphisms of interleukin (IL)-23R rs10889677 and IL-1β rs1143627 were detected by Sanger sequencing.

RESULTS

Compared with HCs (32.5%), methylation level of MINT1 was significantly increased in SCRC (67.2%; P = 0.001) and was a risk factor for CRC (odds ratio, [OR] 4.26). The methylation ratios of COX-2 were 95.0%, 58.0%, 23.1%, and 24.1% in HC, SUC, LUC, and SCRC, respectively, which were negatively correlated with the disease course of UC (r = -0.290). Hypermethylation of COX-2 was a protective factor for SUC (OR, 0.11), LUC (OR, 0.02), and SCRC (OR, 0.03; P < 0.05). Compared with HCs, rs10889677 allele A was a risk factor for SUC and LUC, and rs1143627 allele T was a protective factor for SUC and LUC. Genotype TT was a protective factor for SUC.

CONCLUSION

The hypomethylation of COX-2 gene was a common risk factor and epigenetic modification for UC and SCRC, which might be one of the mechanisms through which UC patients were susceptible to CRC. The hypermethylation of MINT1 was a risk factor for SCRC but not for UC; alleles of IL-23Rrs10889677 and IL-1βrs1143627 were related to UC but not to SCRC.

Elevation of Fasting Ghrelin in Healthy Human Subjects Consuming a High-Salt Diet: A Novel Mechanism of Obesity?

Overweight/obesity is a chronic disease that carries an increased risk of hypertension, diabetes mellitus, and premature death. Several epidemiological studies have demonstrated a clear relationship between salt intake and obesity, but the pathophysiologic mechanisms remain unknown. We hypothesized that ghrelin, which regulates appetite, food intake, and fat deposition, becomes elevated when one consumes a high-salt diet, contributing to the progression of obesity. We, therefore, investigated fasting ghrelin concentrations during a high-salt diet. Thirty-eight non-obese and normotensive subjects (aged 25 to 50 years) were selected from a rural community in Northern China. They were sequentially maintained on a normal diet for three days at baseline, a low-salt diet for seven days (3 g/day, NaCl), then a high-salt diet for seven days (18 g/day). The concentration of plasma ghrelin was measured using an immunoenzyme method (ELISA). High-salt intake significantly increased fasting ghrelin levels, which were higher during the high-salt diet (320.7 ± 30.6 pg/mL) than during the low-salt diet (172.9 ± 8.9 pg/mL). The comparison of ghrelin levels between the different salt diets was statistically-significantly different (p < 0.01). A positive correlation between 24-h urinary sodium excretion and fasting ghrelin levels was demonstrated. Our data indicate that a high-salt diet elevates fasting ghrelin in healthy human subjects, which may be a novel underlying mechanism of obesity.

Impact of endoscopy nurse involvement on polyp detection rates during colonoscopy

AIM: To investigate the impact of endoscopy nurse involvement during colonoscopy on the polyp detection rate (PDR) and adenoma detection rate (ADR).

METHODS: This was a single-center, prospective study. Patients involved were prospectively randomized to a routine colonoscopy group or an endoscopy nurse involvement group. The association of nurse involvement with PDR and ADR was evaluated.

RESULTS: A total of 1192 patients were included in the study. The PDR was significantly higher (33.19% vs 27.81%, P = 0.000) among colonoscopies that included an endoscopy nurse compared with those performed by only a physician, as was the left-sided and the right-sided adenomas detected (P = 0.017). There was no difference in ADR between the two groups (20.88% vs 20.55%, P = 0.889). Nurse participation was associated with a higher detection rate of small (< 5 mm) polyps (P = 0.006).

CONCLUSION: Endoscopy nurse involvement in colonoscopies significantly improves the overall PDR. Involvement of a well-trained nurse in screening colonoscopies may be an effective strategy to increase access.

Effects of salt intake and potassium supplementation on renalase expression in the kidneys of Dahl salt-sensitive rats

Renalase is currently the only known amine oxidase in the blood that can metabolize catecholamines and regulate sympathetic activity. High salt intake is associated with high blood pressure (BP), possibly through the modulation of renalase expression and secretion, whereas potassium can reverse the high salt-mediated increase in blood pressure. However, whether potassium could also modulate BP through renalase is unclear. In this study, we aim to investigate how salt intake and potassium supplementation affect the level of renalase in rats. Eighteen salt-sensitive (SS) and 18 SS-13BN rats were divided into six groups, receiving normal salt (0.3% NaCl), high salt (8% NaCl) and high salt/potassium (8% NaCl and 8% KCl) dietary intervention for four weeks. At the end of experiments, blood and kidneys were collected for analysis. mRNA level of renalase was measured by quantitative real-time PCR and protein level was determined by Western blot. We found that mRNA and protein levels of renalase in the kidneys of SS and SS-13BN rats were significantly decreased (P < 0.05) after high salt intervention, whereas dopamine in plasma was increased (P < 0.05) compared with rats received normal salt, suggesting that salt may induce salt-sensitive hypertension through inhibition of renalase expression. We also found increased mRNA level and protein level of renalase, decreased catecholamine levels in plasma, and decreased BP in SS rats treated with high salt/potassium, compared with that of the high salt SS group. Taken together, the salt-induced increase and potassium-induced decrease in BP could be mediated through renalase. More studies are needed to confirm our findings and understand the underlying mechanisms.

Effect of salt intake and potassium supplementation on brachial-ankle pulse wave velocity in Chinese subjects: an interventional study

Accumulating evidence has suggested that high salt and potassium might be associated with vascular function. The aim of this study was to investigate the effect of salt intake and potassium supplementation on brachial-ankle pulse wave velocity (PWV) in Chinese subjects. Forty-nine subjects (28-65 years of age) were selected from a rural community of northern China. All subjects were sequentially maintained on a low-salt diet for 7 days (3.0 g/day NaCl), a high-salt diet for an additional 7 days (18.0 g/day NaCl), and a high-salt diet with potassium supplementation for a final 7 days (18.0 g/day NaCl+4.5 g/day KCl). Brachial-ankle PWV was measured at baseline and on the last day of each intervention. Blood pressure levels were significantly increased from the low-salt to high-salt diet, and decreased from the high-salt diet to high-salt plus potassium supplementation. Baseline brachial-ankle PWV in salt-sensitive subjects was significantly higher than in salt-resistant subjects. There was no significant change in brachial-ankle PWV among the 3 intervention periods in salt-sensitive, salt-resistant, or total subjects. No significant correlations were found between brachial-ankle PWV and 24-h sodium and potassium excretions. Our study indicates that dietary salt intake and potassium supplementation, at least in the short term, had no significant effect on brachial-ankle PWV in Chinese subjects.

Effect of salt intake and potassium supplementation on serum renalase levels in Chinese adults: a randomized trial

Renalase, a recently discovered enzyme released by the kidneys, breaks down blood-borne catecholamines and may thus regulate blood pressure (BP). Animal studies have suggested that high levels of dietary salt might reduce blood and kidney renalase levels. We conducted a randomized trial to assess the effects of altered salt and potassium intake on serum renalase levels and the relationship between serum renalase levels and BP in humans.Forty-two subjects (28-65 years of age) were selected from a rural community of northern China. All subjects were sequentially maintained on a low-salt diet for 7 days (3.0 g/day of NaCl), a high-salt diet for additional 7 days (18.0 g/day of NaCl), and a high-salt diet with potassium supplementation for final 7 days (18.0 g/day of NaCl + 4.5 g/day of KCl).Serum renalase levels were significantly higher than baseline levels during the low-salt diet intervention period. Renalase levels decreased with the change from the low-salt to high-salt diet, whereas dietary potassium prevented the decrease in serum renalase induced by the high-salt diet. There was a significant inverse correlation between the serum renalase level and 24-h urinary sodium excretion. No significant correlation was found between the renalase level and BP among the different dietary interventions.The present study indicates that variations in dietary salt intake and potassium supplementation affect the serum renalase concentration in Chinese subjects.

Effect of active Notch signaling system on the early repair of rat sciatic nerve injury

It is all known that dedifferentiated Schwann cells (SCs) play an important role in neural regeneration, and Notch signaling has complex and extensive regulatory functions in dedifferentiated SCs. So studies have focused on how to improve peripheral nerve repair by regulating proliferation and dedifferentiation in SCs with Notch signaling meloculars.We have found SCs can be activated when adding Recombinant rat jagged1/FC chimera (an activator of the Notch signaling system) in vivo. Compared with that of the control groups, at 4 weeks post-surgery nerve regeneration and functional rehabilitation in the Recombinant rat jagged1/FC chimera group were advanced significantly, and the expression of neurotrophic factors in the regenerated nerves was elevated largely. These results indicated that SCs activated by Notch signaling could promote nerve repair effectively in the early regenerative stage, suggesting the possible clinical application for the treatment of peripheral nerve defects.

Salt-induced epithelial-to-mesenchymal transition in Dahl salt-sensitive rats is dependent on elevated blood pressure

Dietary salt intake has been linked to hypertension and cardiovascular disease. Accumulating evidence has indicated that salt-sensitive individuals on high salt intake are more likely to develop renal fibrosis. Epithelial-to-mesenchymal transition (EMT) participates in the development and progression of renal fibrosis in humans and animals. The objective of this study was to investigate the impact of a high-salt diet on EMT in Dahl salt-sensitive (SS) rats. Twenty-four male SS and consomic SS-13^BN rats were randomized to a normal diet or a high-salt diet. After 4 weeks, systolic blood pressure (SBP) and albuminuria were analyzed, and renal fibrosis was histopathologically evaluated. Tubular EMT was evaluated using immunohistochemistry and real-time PCR with E-cadherin and alpha smooth muscle actin (α-SMA). After 4 weeks, SBP and albuminuria were significantly increased in the SS high-salt group compared with the normal diet group. Dietary salt intake induced renal fibrosis and tubular EMT as identified by reduced expression of E-cadherin and enhanced expression of α-SMA in SS rats. Both blood pressure and renal interstitial fibrosis were negatively correlated with E-cadherin but positively correlated with α-SMA. Salt intake induced tubular EMT and renal injury in SS rats, and this relationship might depend on the increase in blood pressure.

Clinical efficacy of Lactobacillus acidophilus against experimental murine colitis and its effects on the expression of STAT1, T-bet and GATA3

AIM: To investigate the therapeutic efficacy of Lactobacillus acidophilus against experimental murine colitis and its effects on the expression of STAT1, T-bet and GATA3.

METHODS: Experimental murine colitis was induced with 2.5% dextran sulfate sodium (DSS). A total of 70 mice were randomly and equally divided into seven groups: model control group, negative control group, mesalamine group, low-dose Lactobacillus acidophilus group, medium-dose Lactobacillus acidophilus group, high-dose Lactobacillus acidophilus group and normal control group. The expression of STAT1, T-bet and GATA3 mRNAs in colonic mucosa was measured by reverse transcription-polymerase chain reaction (RT-PCR). The expression of T-bet protein was measured by Western blot and immunohistochemistry (IHC). Colonic tissue damage was assessed using histopathologic score. The body weight and disease activity index (DAI) of all rats were evaluated daily.

RESULTS: Compared with the normal control group, the disease activity index and histopathologic scores were significantly increased (both P < 0.05) in the model control group. All doses of Lactobacillus acidophilus and mesalamine could significantly reduce disease activity index and histopathologic scores when compared to the model control group (6.20 ± 2.64, 5.00 ± 1.21, 5.72 ± 2.63 and 5.81 ± 1.32 vs 7.81 ± 1.02; 4.25 ± 2.05, 2.56 ± 1.81, 2.20 ± 1.12 and 3.10 ± 2.60 vs 5.80 ± 2.94; all P < 0.05). The expression levels of STAT1 and T-bet mRNAs in all Lactobacillus acidophilus groups (low-, medium- and high-dose) and mesalazine group were lower than that in the model control group (all P < 0.05). Moreover, the expression levels of T-bet protein in all Lactobacillus acidophilus groups and mesalazine group were also significantly lower than that in the model control group (0.27 ± 0.04, 0.23 ± 0.02, 0.18 ± 0.04 and 0.27 ± 0.11 vs 0.30 ± 0.04; 0.263 ± 0.045, 0.234 ± 0.015, 0.114 ± 0.025 and 0.252 ± 0.024 vs 0.322 ± 0.064; all P < 0.05). Optimum effects were achieved in the high-dose Lactobacillus acidophilus group.

CONCLUSION: Inhibition of transcriptional factors STAT1/T-bet activation maybe one mechanism contributing to the therapeutic effects of Lactobacillus acidophilus against ulcerative colitis.

Glomerular macrophage proliferation in experimental immune complex nephritis

In immune complex nephritis, glomerular hypercellularity is known to result from the proliferation of intrinsic cells and from the infiltration of mononuclear cells, primarily macrophages. An immunohistochemical double-labeling procedure was used to determine whether macrophages were among the cells which may undergo mitosis within the glomerular tuft. The monoclonal antibody ED1 served as a macrophage marker; cells in the S-phase of mitosis were recognized by uptake of bromodeoxyuridine. Glomerular proliferation was studied in chronic serum sickness of LEW rats, an animal model of immune complex nephritis for which the relationship between immunopathology and pathophysiology has been well described. In normal glomeruli, resident mesangial macrophages accounted for an unexpectedly large proportion (greater than or equal to one-third) of the total mitotic activity. In immune complex glomerulonephritis, the rate of glomerular macrophage proliferation increased rapidly just at the onset of proteinuria and remained high throughout the remaining course of disease. Glomerular macrophages from rats with proliferative nephritis also divided more vigorously than normal in short term culture in vitro, while persistently expressing abnormal surface marker phenotypes. The proliferation of mesangial macrophages appears to be a prominent feature of the normal process of glomerular cell renewal. In hypercellular glomeruli, vigorous local proliferation could greatly amplify the potential of macrophages to cause damage.