Activation of phosphorylating-p38 mitogen-activated protein kinase and its relationship with localization of intestinal stem cells in rats after ischemia-reperfusion injury

Remifentanil Promotes PDIA3 Expression by Activating p38MAPK to Inhibit Intestinal Ischemia/Reperfusion-Induced Oxidative and Endoplasmic Reticulum Stress

Background: Remifentanil protects against intestinal ischemia/reperfusion (I/R) injury; however, its exact mechanism remains to be elucidated. The objective of this study was to investigate the underlying molecular mechanism of remifentanil in intestinal I/R injury in mice.

Methods: We evaluated the intestine-protective effect of remifentanil in adult male mice with 45 min superior mesenteric artery occlusion followed by 4 h reperfusion by determining the following: intestinal Chiu’s scores, diamine oxidase, and intestinal fatty acid binding protein in serum; the apoptotic index, lipid peroxidation product malondialdehyde (MDA), and superoxide dismutase (SOD) activity in the intestinal mucosa; and the intestinal mRNA and protein expressions of Bip, CHOP, caspase-12, and cleaved caspase-3, reflecting endoplasmic reticulum (ER) stress. Furthermore, conditional knockout mice, in which the protein disulfide isomerase A3 (PDIA3) gene was deleted from the intestinal epithelium, and SB203580 (a selective p38MAPK inhibitor) were used to determine the role of PDIA3 and p38MAPK in I/R progression and intestinal protection by remifentanil.

Results: Our data showed that intestinal I/R induced obvious oxidative stress and endoplasmic reticulum stress–related cell apoptosis, as evidenced by an increase in the intestinal mucosal malondialdehyde, a decrease in the intestinal mucosal SOD, and an increase in the apoptotic index and the mRNA and protein expression of Bip, CHOP, caspase-12, and cleaved caspase-3. Remifentanil significantly improved these changes. Moreover, the deletion of intestinal epithelium PDIA3 blocked the protective effects of remifentanil. SB203580 also abolished the intestinal protection of remifentanil and downregulated the mRNA and protein expression of PDIA3.

Conclusion: Remifentanil appears to act via p38MAPK to protect the small intestine from intestinal I/R injury by its PDIA3-mediated antioxidant and anti-ER stress properties.

Advantage of parenteral nutrition for diarrheic calves

This study assessed the advantages of dextrose and amino acid mixture solution as parenteral nutrition (PN) therapy for diarrheic calves. Thirty diarrheic calves were randomly assigned to receive PN (PN group, n=15) or only dextrose solution (Dex group, n=15). The treatment period for the PN group (4.0 days; min-max, 2–10 days) was significantly shorter than that for the Dex group (6.0 days; min-max, 3–21 days) (P<0.01). The PN therapy tended to improve plasma diamine oxidase activity compared with traditional therapy. One potential association between PN therapy and shortened treatment period may be the repair of damaged intestinal villi. Although our proposal has limitations, PN therapy suggested the potential for new treatment of diarrheic calves.

Inhibition of P38 MAPK Downregulates the Expression of IL-1β to Protect Lung from Acute Injury in Intestinal Ischemia Reperfusion Rats

Acute lung injury (ALI) induced by intestinal ischemia/reperfusion (II/R) has high incidence and mortality, in which IL-1β was essential for the full development of ALI. However, the detailed regulating mechanism for this phenomenon remains to be unclear. The purpose of this study was to investigate whether inhibition of P38 MAPK could downregulate the expression of IL-1β to protect lung from acute injury in II/R rats. Here, we found that the level of pulmonary edema at 16 hours after operation (hpo) was obviously enhanced compared to that in 8hpo and sham groups. Immunofluorescent staining demonstrated that IL-1β and P38 MAPK were detected in lung tissues. And rats with II/R have the highest translation level for IL-1β and phosphorylation of P38 MAPK in lung tissues at 16hpo compared with 8hpo and sham groups. Moreover, administration of SB239063, an inhibitor of P38 α and β, could effectively downregulate the expressions of IL-1β and protects lung tissues from injury in II/R rats. Our findings indicate that the inhibition of P38 α and β may downregulate the expression of IL-1β to protect lung from acute injury in II/R, which could be used as a potential target for reducing ALI induced by II/R in the future clinical trial.

miR-300 mediates Bmi1 function and regulates differentiation in primitive cardiac progenitors

B lymphoma Mo-MLV insertion region 1 (Bmi1) is a polycomb-family transcriptional factor critical for self-renewal in many adult stem cells and human neoplasia. We sought to identify microRNAs regulated by Bmi1 that could play a role in multipotent cardiac progenitor cell (CPC) decisions. We found that miR-300, a poorly characterized microRNA mapping in the Dlk1-Dio3 microRNA cluster, was positively regulated by Bmi1 in CPCs. Forced expression of miR-300 in CPCs promoted an improved stemness signature with a significant increase in Oct4 levels, a reduction in senescence progression and an enhanced proliferative status via p19 activation and inhibition of p16 accumulation. Endothelial and cardiogenic differentiation were clearly compromised by sustained miR-300 expression. Additionally, RNA and protein analysis revealed a significant reduction in key cardiac transcription factors, including Nkx2.5 and Tbx5. Collectively, these results suggest that some functions attributed to Bmi1 are due to induction of miR-300, which decreases the cardiogenic differentiation potential of multipotent CPCs in vitro and promotes self-renewal.

Inhibition of p38 MAPK improves intestinal disturbances and oxidative stress induced in a rabbit endotoxemia model

BACKGROUND

Lipopolysaccharide (LPS) decreases intestinal contractility and induces the release of reactive oxygen species, which play an important role in the pathogenesis of sepsis. p38 mitogen-activated protein kinase (MAPK) can be activated by a variety of stimuli such as LPS. The aims of this study were: (i) to investigate the role of p38 MAPK in the effect of LPS on (a) the acetylcholine, prostaglandin E(2) and KCl-induced contractions of rabbit duodenum and (b) the oxidative stress status; (ii) to localize the active form of p38 in the intestine.

METHODS

Rabbits were injected with (i) saline, (ii) LPS, (iii) SB203580, a specific p38 MAPK inhibitor or (iv) SB203580 + LPS. Duodenal contractility was studied in an organ bath. SB203580 was also tested in vitro. The protein expression of p-p38 and total p38 was measured by Western blot and p-p38 was localized by immunohistochemistry. The formation of products of oxidative damage to proteins (carbonyls) and lipids (MDA+4-HDA) was quantified in intestine and plasma.

KEY RESULTS

ACh, PGE(2) and KCl-induced contractions decreased with LPS. LPS increased phospho-p38 expression and the levels of carbonyls and MDA+4-HDA. SB203580 blocked the effect of LPS on the ACh, PGE(2) and KCl-induced contractions in vivo and in vitro and the levels of carbonyls and MDA+4-HDA. P-p38 was detected in neurons of the myenteric plexus and smooth muscle cells of duodenum.

CONCLUSIONS & INFERENCES

Lipopolysaccharide decreases the duodenal contractility in rabbits and increases the production of free radicals. p38 MAPK is a mediator of these effects.

The role of p38b MAPK in age-related modulation of intestinal stem cell proliferation and differentiation in Drosophila

It is important to understand how age-related changes in intestinal stem cells (ISCs) may contribute to age-associated intestinal diseases, including cancer. Drosophila midgut is an excellent model system for the study of ISC proliferation and differentiation. Recently, age-related changes in the Drosophila midgut have been shown to include an increase in ISC proliferation and accumulation of mis-differentiated ISC daughter cells. Here, we show that the p38b MAPK pathway contributes to the age-related changes in ISC and progenitor cells in Drosophila. D-p38b MAPK is required for an age-related increase of ISC proliferation. In addition, this pathway is involved in age and oxidative stress-associated mis-differentiation of enterocytes and upregulation of Delta, a Notch receptor ligand. Furthermore, we also show that D-p38b acts downstream of PVF2/PVR signaling in these age-related changes. Taken together, our findings suggest that p38 MAPK plays a crucial role in the balance between ISC proliferation and proper differentiation in the adult Drosophila midgut.

Molecular analysis for differential diagnosis of small bowel obstruction: expression of proinflammatory cytokines and diamine oxidase activity

BACKGROUND

A small bowel obstruction is classified as simple (nonstrangulated) or strangulated. The early recognition with correct diagnosis of small bowel obstruction is a critical issue as the release from strangulation requires surgical emergency.

METHODS

To evaluate the physiological effect on small bowel obstruction, a metallic ring was put in the small intestine (simple ileus) and a loop obstruction was made with keeping the blood flow (strangulated obstruction). Serum level of cytokines, IL-6, TNF-α, and IL-1β as well as endotoxin and seromuscular enzymes, CPK and LDH, were serially analyzed. Serum and mucosal DAO activity were also assessed.

RESULTS

Endotoxin was increased at 18 h through 48 h in strangulated obstruction, but not detected in the simple ileus. Early proinflammatory cytokines were significantly elevated in strangulated obstruction. High expression of IL-6 prolonged after 12h. Transiently expressed IL-1β peaked at 12h, TNF-α was increased at 18 h. In simple ileus, these expressions of cytokines were low and slow. LDH and CPK were significantly elevated at 48h, but there were no difference between simple ileus and strangulated obstruction. Serum DAO activity was significantly increased in simple ileus, but gradually decreased in strangulated obstruction, while mucosal DAO activity was decreased in both groups.

CONCLUSIONS

High level of serum IL-6 is an early marker for strangulated obstruction. The pattern of serum DAO activity, decrease in strangulated obstruction and increase in simple ileus, might be useful molecular parameter in the early and proper diagnosis of small bowel obstruction.

Acid fibroblast growth factor reduces rat intestinal mucosal damage caused by ischemia-reperfusion insult

AIM: To detect the effects of acid fibroblast growth factor (aFGF) on apoptosis and proliferation of intestinal epithelial cells in differentiation or proliferation status to explore the protective mechanisms of aFGF.

METHODS: Wistar rats were randomly divided into sham-operated control group (C, n = 6), intestinal ischemia group (I, n = 6), aFGF treatment group (A, n = 48) and intestinal ischemia-reperfusion group (R, n = 48). Apoptosis of intestinal mucosal cells was determined with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) technique. Proliferating cell nuclear antigen (PCNA) protein expression and distribution were detected with immunohistochemical method. Plasma levels of D-lactate were determined with modified Brandts method.

RESULTS: In A group, administration of exogenous aFGF could improve intestinal histological structure and decrease plasma D-lactate levels at 2-12 h after the reperfusion compared with R group. The apoptotic rates and PCNA protein expressions were not increased until 2 h after reperfusion and were maximal at 12 h. After reperfusion for 2-12 h, the apoptotic rates were gradually augmented along the length of jejunal crypt-villus units. Administration of aFGF could significantly reduce the apoptotic response at 2-12 h after reperfusion (P<0.05). Apoptosis rates in villus and crypt epithelial cells in A group at 12 h after reperfusion were (62.5±5.5)% and (73.2±18.6)% of those in R group, respectively. Treatment of aFGF could apparently induce protein expression of PCNA in intestinal mucosal cells of A group compared with R group during 2-12 h after reperfusion (P<0.05). There were approximately 1.3- and 1.5-times increments of PCNA expression levels in villus and crypt cells in A group at 12 h after reperfusion compared with R group, respectively.

CONCLUSION: Intestinal I/R insult could lead to histological structure change and apoptotic rate increment. The protective effects of aFGF against ischemia/reperfusion in rat intestinal mucosa might be partially due to its ability to inhibit ischemia/reperfusion-induced apoptosis and to promote cell proliferation of crypt cells and villus epithelial cells.

Inhibition of p38 mitogen-activated protein kinase may decrease intestinal epithelial cell apoptosis and improve intestinal epithelial barrier function after ischemia- reperfusion injury

AIM: To investigate the role of p38 mitogen-activated protein kinase in rat small intestine after ischemia-reperfusion (I/R) insult and the relationship between activation of p38 MAPK and apoptotic cell death of intestine.

METHODS: Ninety Wistar rats were divided randomly into three groups, namely sham-operated group (C), I/R vehicle group (R) and SB203580 pre-treated group (S). In groups R and S, the superior mesenteric artery (SMA) was separated and occluded for 45 min, then released for reperfusion for 0.25, 0.5, 1, 2, 6, 12 and 24 h. In group C, SMA was separated without occlusion. Plasma D-lactate levels were examined and histological changes were observed under a light microscope. The activity of p38 MAPK was determined by Western immunoblotting and apoptotic cells were detected by the terminal deoxynucleotidyl transferase (TdT)-mediated dUDP-biotin nick end labeling (TUNEL).

RESULTS: Intestinal ischemia followed by reperfusion activated p38 MAPK, and the maximal level of activation (7.3-fold vs sham-operated group) was reached 30 min after I/R. Treatment with SB 203580, a p38 MAPK inhibitor, reduced intestinal apoptosis (26.72±3.39% vs 62.50±3.08% in I/R vehicle, P<0.01) and decreased plasma D-lactate level (0.78±0.15 mmol/L in I/R vehicle vs 0.42±0.17 mmol/L in SB-treated group) and improved post-ischemic intestinal histological damage.

CONCLUSION: p38 MAPK plays a crucial role in the signal transduction pathway mediating post-ischemic intestinal apoptosis, and inhibition of p38 MAPK may attenuate ischemia-reperfusion injury.

Effects of extrogenous aFGF on bax and bcl-2 expression in intestinal cells after ischemia/reperfusion

AIM: To detect the effects of acid fibroblast growth factor (aFGF) on apoptosis and Bax and bcl-2 expression in rat intestine after I/R injury, and to explore the protective mechanisms of aFGF on intestinal villus.

METHODS: One hundred and eight Wistar rats were randomly divided into 4 groups, namely intestinal ischemia/reperfusion group (R, n = 48), intestinal ischemia group (I, n = 6), aFGF treatment group (A, n = 48) and sham-operated group (C, n = 6). The rats sustained 45 min of arteria mesenterica (SMA) occlusion to establish the ischemia model. At the beginning of reperfusion, rats in group R and A were treated with normal saline (0.15 mL) and aFGF (20 μg/kg, 0.15 mL) respectively. Then each six rats as a sub-group were reperfused for a duration of 0.25, 0.5, 1, 2, 6, 12, 24, 48 h respectively. Cell apoptotic rates in intestinal villus were determined with terminal deoxynucl-eotidy transferase mediated dUTP-biotin nick-end-labeling technique (TUNEL). RT-PCR was used to detect the expressions of bax and bcl-2 gene in intestinal villus. Immunohistochemical methods were adopted to detect bax and bcl-2 protein expressions and distributions.

RESULTS: The improvement of intestinal histological structures was observed at 2 h, 6 h and 12 h after the reperfusion in group A, compared with group R. The apoptotic rates were (41.17±3.49 %), (42.83±5.23 %) and (53.33±6.92 %) at 2, 6, 12 h after reperfusion respectively in group A, and these rates were significantly lower than those in group R (P < 0.05). The expressions of bax gene and bax protein in intestinal villus were gradually increased after ischemia/reperfusion, while the transcription of bcl-2 gene and expression of bcl-2 protein were decreased. During the 2-12 h of reperfusion, the transcription of bcl-2 gene and expression of bcl-2 protein were significantly increased in group A compared with those in group R (P < 0.05). However, the expressions of bax gene and bax protein were significantly higher than those in group R (P < 0.05).

CONCLUSION: Intravenous aFGF could alleviate I/R-induced injury, in which its effects on the facilitation of bcl-2 transcription and inhibition of bax expression may play an important role.