Early anastomotic repair in the rat intestine is affected by transient preoperative mesenteric ischemia

NLRX1/FUNDC1/NIPSNAP1-2 axis regulates mitophagy and alleviates intestinal ischaemia/reperfusion injury

OBJECTIVES

Mitophagy is considered to be a key mechanism in the pathogenesis of intestinal ischaemic reperfusion (IR) injury. NOD-like receptor X1 (NLRX1) is located in the mitochondria and is highly expressed in the intestine, and is known to modulate ROS production, mitochondrial damage, autophagy and apoptosis. However, the function of NLRX1 in intestinal IR injury is unclear.

MATERIALS AND METHODS

NLRX1 in rats with IR injury or in IEC-6 cells with hypoxia reoxygenation (HR) injury were measured by Western blotting, real-time PCR and immunohistochemistry. The function of NLRX1-FUNDC1-NIPSNAP1/NIPSNAP2 axis in mitochondrial homeostasis and cell apoptosis were assessed in vitro.

RESULTS

NLRX1 is significantly downregulated following intestinal IR injury. In vivo studies showed that rats overexpressing NLRX1 exhibited resistance against intestinal IR injury and mitochondrial dysfunction. These beneficial effects of NLRX1 overexpression were dependent on mitophagy activation. Functional studies showed that HR injury reduced NLRX1 expression, which promoted phosphorylation of FUN14 domain-containing 1 (FUNDC1). Based on immunoprecipitation studies, it was evident that phosphorylated FUNDC1 could not interact with the mitophagy signalling proteins NIPSNAP1 and NIPSNAP2 on the outer membrane of damaged mitochondria, which failed to launch the mitophagy process, resulting in the accumulation of damaged mitochondria and epithelial apoptosis.

CONCLUSIONS

NLRX1 regulates mitophagy via FUNDC1-NIPSNAP1/NIPSNAP2 signalling pathway. Thus, this study provides a potential target for the development of a therapeutic strategy for intestinal IR injury.

Aggravated intestinal ischemia‑reperfusion injury is associated with activated mitochondrial autophagy in a mouse model of diabetes

Numerous studies have reported that diabetes is associated with an increased susceptibility to cardiac ischemia- reperfusion injury; however, the mechanism underlying the role of diabetes during intestinal ischemia-reperfusion (IIR) has yet to be elucidated. The present study evaluated the intestinal pathological alterations and possible underlying mechanisms in a mouse model of type 1 diabetes mellitus with IIR. The effects of diabetes were investigated by assessing the histopathology, oxidative stress, inflammatory cytokine levels in intestine tissues and blood plasma, and protein expression levels of phosphatase and tensin homolog-induced putative kinase (PINK1), Parkin and the ratio of light chain 3B (LC3B) II/I. The results demonstrated that diabetes increased the Chiu's intestinal injury score, concentration of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, and levels of oxidative stress. Furthermore, the alterations were more pronounced in the diabetes with IIR group. The expression levels of PINK1 and Parkin, as well as the ratio of LC3BII/I, were significantly upregulated in the IIR group compared with the Sham group. Diabetes activated PINK1 and Parkin, and increased the expression of LC3BII. Furthermore, transmission electron microscopy revealed that mitochondrial destruction and the number of autophagosomes was increased in the diabetic groups compared with the non-diabetic groups. Collectively, the results of the present study suggest that diabetes increased intestinal vulnerability to IIR by enhancing inflammation and oxidative stress. Furthermore, IIR was associated with overactivation of mitochondrial autophagy; therefore, the increased vulnerability to IIR-induced intestine damage due to diabetes may be associated with PINK1/Parkin-regulated mitochondrial autophagy.

Reconstructive Surgery for Intestinal Failure

BACKGROUND

Intestinal failure (IF) in the adult is the result of a wide spectrum of disease. Acute mesenteric ischemia, postoperative short bowel due to a complicative course, and Crohn's disease are major causes of IF. Reconstructive surgery in the context of IF comprises a spectrum of procedures including stoma takedown, reversal of laparostomies, and closure of enteric fistulas.

METHODS

This article is based on a PubMed-based literature search and personal experience in adult patients with IF.

RESULTS

This review summarizes therapeutic options of reconstructive surgery in adult patients focusing on the main reasons of IF such as mesenteric ischemia, complicative previous surgery, and Crohn's disease. Indications and contraindications are discussed as well as the optimal time point of reconstructive surgery.

CONCLUSION

This overview summarizes surgical aspects in a special cohort of patients with a rare disease entity necessitating an interdisciplinary approach.

Healing of Ischemic Colon Anastomosis in Rats Could Be Provided by Administering Dexpanthenol or Coenzyme Q10

Background: In this study, the effectiveness of dexpanthenol and coenzyme Q10 (CoQ10) on the healing of ischemic colon anastomosis was investigated. Methods: Forty eight male Wistar Albino rats were divided into four equal groups (Sham-S, Sham-I, DXP, Q10). Following full layer colon resection, single layer colon anastomosis, without creating ischemia, was performed on the Sham-S group. The same experimental model was performed on remaining groups after ischemia was created. Intraperitoneal dexpanthenol and CoQ10 was administered to the DXP and Q10 groups once a day for three days. Ten days later, all colon anastomoses were investigated histopathologically and biochemically, as well as their burst pressure values, in all sacrificed rats. Results: The highest burst pressure value was observed in the Sham-S group, decreasing from high to low in the DXP, Q10, and Sham-I groups, respectively (p = 0.008). Furthermore, tissue hydroxyproline (p = 0.001) level values were significantly different among the groups. Additionally, histopathological analysis revealed a significant difference among groups regarding reepithelization (p = 0.027) and polymorphonuclear leukocyte density (p = 0.022). Conclusions: This preliminary study has shown that ischemia-reperfusion injury may impair the healing of colon anastomosis and it has been concluded that dexpanthenol and CoQ10 may have positive effects on the healing of ischemic colon anastomosis in rat, although re-epithelization may be adversely affected using CoQ10.

The effect of carbon dioxide pneumoperitoneum on the healing colonic anastomosis in rats

PURPOSE

To investigate the effects of pneumoperitoneum on colonic anastomosis healing.

METHODS

Colonic anastomosis was performed in 120 rats divided into four groups: Group I - pneumoperitoneum before laparotomy, Group II - pneumoperitoneum after laparorrhaphy, Group III - pneumoperitoneum before laparotomy and after laparorrhaphy, Group IV - no pneumoperitoneum (control group). Pneumoperitoneum pressure was 5 mmHg. Animals were killed on the 3rd, 7th and 14th postoperative day. Histopathological features, anastomosis breaking strength, collagen histomorphometry and hydroxyproline concentration were assessed.

RESULTS

Breaking strength between groups: (day 3, p=0.165; day 7, p=0.219; day 14, p=0.539). Histopathology revealed that group II had, on day 7, less infiltration of mononuclear cells (p=0.006), greater infiltration of polymorphonuclear cells (p=0.001) and greater necrosis (p=0.001); and on day 14, less fibrosis. Histomorphometry revealed a decrease in collagen in groups I and III (p<0.001) on day 7 and an increase in groups I and II on day 14 (p<0.001). Hydroxyproline concentration was similar for groups on days 3 (p=0.152), 7 (p=0.913) or 14 (p=0.981).

CONCLUSION

Carbon dioxide does not impair the healing of colonic anastomosis in rats.

Examining the safety of colon anastomosis on a rat model of ischemia-reperfusion injury

Introduction

Intestinal ischemia and reperfusion can impair anastomotic strength.

The purpose of this study was to evaluate the safety of delayed colon anastomosis following remote ischemia-reperfusion (IR) injury.

Methods

Rats divided into two groups underwent bilateral groin incisions, however only the study group had femoral artery clamping to inflict IR injury. Twenty-four hours following this insult, the animals underwent laparotomy, incision of the transverse colon and reanastomosis. End points included anastomotic leakage, strength and histopathological features.

Results

Anastomotic leak among IR animals (22.2%) was not statistically different in comparison to the controls [10.5% (p = 0.40)]. Anastomotic mean burst pressures showed no statistically significant difference [150.6 ± 15.57 mmHg in the control group vs. 159.9 ± 9.88 mmHg in the IR group (p = 0.64)]. The acute inflammatory process in the IR group was similar to controls (p = 0.26), as was the chronic repair process (p = 0.88). There was no significant difference between the inflammation:repair ratios amongst the two groups (p = 0.67).

Conclusion

Primary colon repair is safe when performed 24 hours following systemic IR injury.

Recombinant vascular endothelial growth factor165 gene therapy improves anastomotic healing in an animal model of ischemic esophagogastrostomy

Proper anastomotic healing is dependent upon many factors including adequate blood flow to healing tissue. The aim of this study was to investigate the impact of vascular endothelial growth factor (VEGF(165)) transfection on anastomotic healing in an ischemic gastrointestinal anastomosis model. Utilizing an established opossum model of esophagogastrectomy followed by esophageal-gastric anastomosis, the gastric fundus was transfected with recombinant human vascular endothelial growth factor via direct injection of a plasmid-based nonviral delivery system. Twenty-nine animals were divided into three groups: two concentrations of VEGF and a control group. Outcomes included VEGF mRNA transcript levels, neovascularization, tissue blood flow, and anastomotic bursting pressure. To determine whether local injection resulted in a systemic effect, distant tissues were evaluated for VEGF transcript levels. Successful gene transfection was demonstrated by quantitative polymerase chain reaction analysis of anastomotic tissue, with significantly higher VEGF mRNA expression in treated animals compared to controls. At the gastric side of the anastomosis, there was significantly increased neovascularization, blood flow, and bursting pressure in experimental animals compared to controls. There were no differences in outcome measures between low- and high-dose VEGF groups; however, the high-dose group demonstrated increased VEGF mRNA expression across the anastomosis. VEGF production was not increased at distant sites in treated animals. In this animal model, VEGF gene therapy increased VEGF transcription at a healing gastrointestinal anastomosis without systemic VEGF upregulation. This treatment led to improved healing and strength of the acutely ischemic anastomosis. These findings suggest that VEGF gene therapy has the potential to reduce anastomotic morbidity and improve surgical outcomes in a wide array of patients.

Adipose-tissue-derived Stem Cells Enhance the Healing of Ischemic Colonic Anastomoses: An Experimental Study in Rats

Purpose

This experimental study verified the effect of adipose-tissue-derived stem cells (ASCs) on the healing of ischemic colonic anastomoses in rats.

Methods

ASCs were isolated from the subcutaneous fat tissue of rats and identified as mesenchymal stem cells by identification of different potentials. An animal model of colonic ischemic anastomosis was induced by modifying Nagahata's method. Sixty male Sprague-Dawley rats (10-week-old, 370 ± 50 g) were divided into two groups (n = 30 each): a control group in which the anastomosis was sutured in a single layer with 6-0 polypropylene without any treatment and an ASCtreated group (ASC group) in which the anastomosis was sutured as in the control group, but then ASCs were locally transplanted into the bowel wall around the anastomosis. The rats were sacrificed on postoperative day 7. Healing of the anastomoses was assessed by measuring loss of body weight, wound infection, anastomotic leakage, mortality, adhesion formation, ileus, anastomotic stricture, anastomotic bursting pressure, histopathological features, and microvascular density.

Results

No differences in wound infection, anastomotic leakage, or mortality between the two groups were observed. The ASC group had significantly more favorable anastomotic healing, including less body weight lost, less ileus, and fewer ulcers and strictures, than the control group. ASCs augmented bursting pressure and collagen deposition. The histopathological features were significantly more favorable in the ASC group, and microvascular density was significantly higher than it was in the control group.

Conclusion

Locally-transplanted ASCs enhanced healing of ischemic colonic anastomoses by increasing angiogenesis. ASCs could be a novel strategy for accelerating healing of colonic ischemic risk anastomoses.

The influence of the CO₂ pneumoperitoneum on a rat model of intestinal anastomosis healing

Background

The CO₂ pneumoperitoneum, which is used for laparoscopic surgery, causes local and systemic effects in patients. Concern arises about what the pressurized anoxic environment of the CO₂ pneumoperitoneum has on intestinal healing. Earlier experimental work showed a negative correlation between intestinal healing and the applied intra-abdominal pressure. To further elucidate this, we developed a rat model, in which enterotomy healing can be compared after open or laparoscopic surgery. Possible mechanisms of injury, such as impaired neoangiogenesis or injury through hypoxia-induced pathways were studied.

Methods

A new experimental mechanically ventilated rat model was developed. An enterotomy was made and closed via laparotomy (group I) or laparoscopy under CO₂ pressures of 5 mmHg (group II) or 10 mmHg (group III). Intestinal healing was tested in vivo after 1 week by bursting-pressure analysis. The effect of the operative procedure on neoangiogenesis was tested by counting factor VIII positive vessels in biopsies of the perianastomotic granulation tissue after 1 week. Intestinal anoxia was tested by quantifying HIF-1α protein levels in intestinal biopsies, taken before the enterotomy closure.

Results

The bursting pressures were significantly lower after laparoscopic surgery at 10 mmHg CO₂ pneumoperitoneum (group III) compared with rats that had undergone open surgery (group I) or laparoscopic surgery at 5 mmHg CO₂ pneumoperitoneum (group II). There was no significant quantitative difference between the three groups in the neoangiogenesis nor was there a difference in the amount of HIF-1α measured in the intestinal biopsies.

Conclusions

We developed a surgical model that is well fitted to study the effects of pneumoperitoneum on intestinal healing. With this model, we found further evidence of CO₂ pressure-dependant hampered intestinal healing. These differences could not be explained by difference in neoangiogenesis nor local upregulation of hypoxic factors.