Interstitial cells of Cajal in dysmotility in intestinal ischemia and reperfusion injury in rats

"M1/M2" Muscularis Macrophages Are Associated with Reduction of Interstitial Cells of Cajal and Glial Cells in Achalasia

BACKGROUND AND AIMS

Several studies showed muscularis macrophages (MMφ) are associated with GI motility disorders. The purpose of this study was to preliminary explore the association between MMφ and achalasia.

METHODS

Tissue samples of the lower esophageal sphincter (LES) high-pressure zone were obtained from 27 achalasia patients and 10 controls. Immunohistochemistry for MMφ, interstitial cells of Cajal (ICC), neuronal nitric oxide synthase (nNOS), and glial cells were conducted. Histological characteristics were compared between groups, and correlation analysis was performed.

RESULTS

Fewer ICC was found in achalasia compared with controls (P = 0.018), and the level of M1 macrophages was higher than that in controls no matter in terms of the number or the proportion of M1(P = 0.026 for M1 and 0.037 for M1/MMφ). Statistical differences were found between two groups in terms of proportion of M2 and ratio of M1 to M2 (P = 0.048 for M2/ MMφ and < 0.001 for M1/M2). For the correlation analysis, significant correlations were detected between levels of nNOS, ICC, and glial cells in patients with achalasia (P = 0.026 for nNOS and ICC, 0.001 for nNOS and glial cells, 0.019 for ICC and glial cells). There were significant correlations between M2/MMφ and levels of ICC (P = 0.019), glial cells (P = 0.004), and nNOS (P = 0.135).

CONCLUSION

Patients with achalasia had a higher level of M1/M2 ratio in LES and significant correlations were found between M2/MMφ and numbers of ICC and glial cells, which suggested that MMφ were probably associated with occurrence and development of achalasia.

Gut Microbiota and Probiotics/Synbiotics for Modulation of Immunity in Critically Ill Patients

Patients suffering from critical illness have host inflammatory responses against injuries, such as infection and trauma, that can lead to tissue damage, organ failure, and death. Modulation of host immune response as well as infection and damage control are detrimental factors in the management of systemic inflammation. The gut is the motor of multiple organ failure following injury, and it is recognized that gut dysfunction is one of the causative factors of disease progression. The gut microbiota has a role in maintaining host immunity, and disruption of the gut microbiota might induce an immunosuppressive condition in critically ill patients. Treatment with probiotics and synbiotics has been reported to attenuate systemic inflammation by maintaining gut microbiota and to reduce postoperative infectious complications and ventilator-associated pneumonia. The administration of prophylactic probiotics/synbiotics could be an important treatment option for preventing infectious complications and modulating immunity. Further basic and clinical research is needed to promote intestinal therapies for critically ill patients.

Interstitial cells of Cajal are diminished in critically ill patients: Autopsy cases

OBJECTIVE

Gastrointestinal dysmotility in critically ill patients is important as enteral nutrition is crucial. However, normal gut motility is impaired under conditions of critical illness subsequent to severe insult. Interstitial cells of Cajal (ICC) form an extensive network associated with the myenteric plexus in the enteric nervous system. There are few reports about ICC distribution in critically ill patients. The aim of this study was to evaluate ICC in critically ill patients.

METHODS

Postmortem colon harvest was obtained from critically ill patients. Control specimens were obtained from patients without bowel movement problems who underwent hemicolectomy. The tissues were stained with c-Kit for ICC. The number of ICC was identified by counting from 10 high-power fields (HPFs).

RESULTS

Specimens from six patients were analyzed and compared with those from six control patients. All patients had abnormalities of crypt architecture and inflammatory cell infiltrations. Mucosal thickness tended to be lower in the critically ill patients than in the controls (147 ± 47 versus 231 ± 127 μm; P = 0.15). Muscle layer thickness tended to be higher in the critically ill patients than in the controls (494 ± 163 versus 394 ± 258 μm; P = 0.44). ICC in the critically ill patients were almost depleted in the colon compared with those in the controls. Significantly fewer ICC were present in the critically ill patients than in the controls (0.45 versus 7.25 cells/HPF; P < 0.05).

CONCLUSIONS

Critical illness is associated with diminished numbers of ICC in the colon. This finding could have implications for dysmotility in critically ill patients.

Muscularis macrophages: Key players in intestinal homeostasis and disease

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Muscularis macrophages densily colonize the outermost layer of the gastrointestinal tract.

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Muscularis macrophages communicate with enteric neurons in a bidirectional matter.

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Muscularis macrophages are tissue-protective but can contribute to disease.

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Current challenges are to decipher therapeutic potentials of muscularis macrophages.

Macrophages residing in the muscularis externa of the gastrointestinal tract are highly specialized cells that are essential for tissue homeostasis during steady-state conditions as well as during disease. They are characterized by their unique protective functional phenotype that is undoubtedly a consequence of the reciprocal interaction with their environment, including the enteric nervous system. This muscularis macrophage-neuron interaction dictates intestinal motility and promotes tissue-protection during injury and infection, but can also contribute to tissue damage in gastrointestinal disorders such as post-operative ileus and gastroparesis. Although the importance of muscularis macrophages is clearly recognized, different aspects of these cells remain largely unexplored such their origin, longevity and instructive signals that determine their function and phenotype. In this review, we will discuss the phenotype, functions and origin of muscularis macrophages during steady-state and disease conditions. We will highlight the bidirectional crosstalk with neurons and potential therapeutic strategies that target and manipulate muscularis macrophages to restore their protective signature as a treatment for disease.

Nitric oxide-induced oxidative stress impairs pacemaker function of murine interstitial cells of Cajal during inflammation

The pacemaker function of interstitial cells of Cajal (ICC) is impaired during intestinal inflammation. The aim of this study is to clarify the pathophysiological mechanisms of ICC dysfunction during inflammatory condition by using intestinal cell clusters. Cell clusters were prepared from smooth muscle layer of murine jejunum and treated with interferon-gamma and lipopolysaccharide (IFN-γ+LPS) for 24h to induce inflammation. Pacemaker function of ICC was monitored by measuring cytosolic Ca(2+) oscillation in the presence of nifedipine. Treatment with IFN-γ+LPS impaired the pacemaker activity of ICC with increasing mRNA level of interleukin-1 beta, tumor necrosis factor-alpha and interleukin-6 in cell clusters; however, treatment with these cytokines individually had little effect on pacemaker activity of ICC. Treatment with IFN-γ+LPS also induced the expression of inducible nitric oxide synthase (iNOS) in smooth muscle cells and resident macrophages, but not in ICC. Pretreatment with NOS inhibitor, L-NAME or iNOS inhibitor, 1400W ameliorated IFN-γ+LPS-induced pacemaker dysfunction of ICC. Pretreatment with guanylate cyclase inhibitor, ODQ did not, but antioxidant, apocynin, to suppress NO-induced oxidative stress, significantly suppressed the impairment of ICC function induced by IFN-γ+LPS. Treatment with IFN-γ+LPS also decreased c-Kit-positive ICC, which was prevented by pretreatment with L-NAME. However, apoptotic ICC were not detected in IFN-γ+LPS-treated clusters, suggesting IFN-γ+LPS stimulation just changed the phenotype of ICC but not induced cell death. Moreover, ultrastructure of ICC was not disturbed by IFN-γ+LPS. In conclusion, ICC dysfunction during inflammation is induced by NO-induced oxidative stress rather than NO/cGMP signaling. NO-induced oxidative stress might be the main factor to induce phenotypic changes of ICC.

Interstitial cells of Cajal are decreased in patients with gastroschisis associated intestinal dysmotility

BACKGROUND

Gastroschisis associated intestinal dysmotility (GAID) is poorly understood. Animal experiments suggest that interstitial cells of Cajal (ICC), play an important role.

METHODS

Infants with gastroschisis (GS) and GAID (time to full feed >42days) were selected. Age matched GS and control (NEC, ileal atresia, malrotation, and volvulus) samples from primary (T1) and secondary (T2) time points underwent standard histopathology and immunohistochemistry for identification of ICC, followed by evaluation of ICC numbers, distribution, morphology, relation to ganglion cells, and myenteric plexus architecture. Groups were compared using parametric and nonparametric tests.

MAIN RESULTS

Twelve patients had samples available for histopathological evaluation. GAID patients had a significantly lower total number of ICCs than controls (3 vs. 8, P<0.0029). ICC number at T1 was 2.5 vs. 6 (P=0.0629) and significantly lower at T2. (3.5 vs. 11, P=0.0124). GAID patients did not show a significant increase of ICC from T1 to T2. Controls showed a significant increase of ICC over time (6 vs. 11, P=0.0408).

CONCLUSION

Intestinal samples from infants with GAID who underwent stoma formation demonstrated fewer ICC than controls. There was no improvement or cell recovery during the study period. The ability to modulate ICC may have significant implications for the management of GAID.

Anti-oxidative stress effect of proanthocyanidin on intestinal mucosa of rats with limb ischemia-reperfusion injury

AIM: To investigate the protective effect of proanthocyanidin (PC) on the intestinal mucosa of rats with limb ischemia-reperfusion (LI/R) and to explore the possible mechanism.

METHODS: Twenty-one male adult Sprague-Dawley rats were randomly divided into three groups (n = 7): sham operation group, LI/R group and PC group. The PC group received 100 mg/(kg•d) PC via oral gavage for 7 d before LI/R. The sham operation and LI/R groups were given the same dose of salad oil each day for 7 d. A tourniquet was used to tie the rat left hind limb to induce LI/R injury in rats (ischemia 3 h and reperfusion 18 h). Following reperfusion, the abdominal cavity was opened and blood samples were taken from the abdominal aorta to determine serum superoxide dismutase (SOD) and malondialdehyde (MDA) levels. Segments of the ileum were quickly resected and equally separated into two parts to conduct hematoxylin & eosin (H&E) staining and determine tissue secretory immunoglobulin A (sIgA) levels, respectively.

RESULTS: Compared with the sham operation group, serum SOD activity was significantly decreased (P < 0.01), MDA levels were significantly increased (P < 0.01), mucosal injury was significantly aggravated in light microscopic evaluations (P < 0.01) and tissue sIgA (P < 0.01) was significantly reduced after LI/R. Compared with the LI/R group, pretreatment with PC significantly enhanced serum SOD activity (P < 0.05), decreased MDA levels (P < 0.01), mitigated intestinal mucosal injury (P < 0.01) and increased the tissue sIgA contents (P < 0.05).

CONCLUSION: PC protects the intestinal mucosa by elevating serum SOD activity, reducing MDA levels and increasing tissue sIgA contents in rats after LI/R injury.

The effects of female sexual steroids on gastric function and barrier resistance of gastrointestinal tract following traumatic brain injury

AIM

The aim was to assess the alteration of gastric function and barrier function of gastrointestinal (GI) tract following diffuse brain injury in varying ovarian hormone status.

MATERIALS AND METHODS

Diffuse traumatic brain injury (TBI) was induced by Marmarou method. Rats were randomly assigned into 10 groups: Intact, sham + ovariectomized female (OVX), TBI, TBI + OVX, vehicle, estradiol (E2), progesterone (P), E2 + P, estrogen receptor alpha agonist and estrogen receptor beta agonist (DPN). Endotoxin levels were measured using enzyme-linked immunosorbent assay method. All the parameters were measured 5 days after TBI.

RESULTS

Intragastric pressure was significantly decreased in TBI as compared to the intact group (P < 0.001) and this was lower in TBI group versus TBI + OVX group (P < 0.05). Pretreatment with steroid hormones and their agonists did not have any effect on the gastric pressure compared to TBI + OVX or vehicle groups. Inflammation, congestion, ulcer and erosion were seen in the TBI rats. All treatment groups worsen the tissue condition so that the presence of thrombosis also was seen. The trauma induction did not have any effect on the serum and intestinal endotoxin levels. DPN had caused a significant reduction in serum levels of endotoxin compared with OVX + TBI group (P < 0.05).

CONCLUSION

Pretreatment with sexual steroids is not useful in the treatment of GI dysfunction induced by TBI. The treatment with all sexual female hormones worsens the gastric tissue condition. Furthermore, the applied weight was not enough for releasing of endotoxin. It seems that estrogen reduced the endotoxin levels by estrogen beta receptor.

Involvement of interstitial cells of Cajal in experimental severe acute pancreatitis in rats

AIM: To observe the changes in interstitial cells of Cajal (ICC) in rats with experimental severe acute pancreatitis (SAP).

METHODS: A total of twenty-four SD rats were randomly divided into two groups (n = 12), namely the sham (S) group and the SAP group; the SAP rat model was established by retrograde injection of 5% sodium taurocholate (1.0 mL/kg) into the pancreatic duct. Twenty-four hours later intestinal motility was assessed by testing small intestinal propulsion rate, and then the rats were sacrificed. The pancreas and jejunum were resected and underwent routine pathologic examination. Immunohistochemical staining was used to detect c-kit-positive cells in the jejunum. Expression of c-kit mRNA was detected by real-time polymerase chain reaction, and the expression of c-kit protein was evaluated by Western blotting. Ultrastructure of ICC was evaluated by transmission electron microscopy.

RESULTS: There was bleeding, necrosis and a large amount of inflammatory cell infiltration in pancreatic tissue in the SAP group, while in jejunal tissue we observed a markedly denuded mucosal layer, loss of villous tissue and a slightly dilated muscular layer. The small intestinal propulsion rate was 68.66% ± 2.66% in the S group and 41.55% ± 3.85% in the SAP group. Compared with the S group, the rate of the SAP group decreased sharply. The density of c-kit-positive cells in the SAP group was significantly lower than in the S group; the respective mean densities were 88.47 ± 10.49 in the S group and 56.11 ± 7.09 in the SAP group. The levels of c-kit protein and mRNA were 0.36 ± 0.04 and 1.29 ± 0.91 in the SAP group, respectively, which were significantly lower than those in the S group (0.53 ± 0.06, 0.64 ± 0.33, respectively). In the SAP group, ICC profiles showed the same change tendency, such as vacuolation of mitochondria, irregular vacuoles and loosened desmosome-like junctions.

CONCLUSION: Decreased c-kit-positive cells and ultrastructural changes in ICC resulting from blockade of the c-kit signaling pathway are involved in the intestinal dysmotility associated with SAP.

Effect of octreotide on enteric motor neurons in experimental acute necrotizing pancreatitis

Background/Aims

Amelioration of intestinal dysmotility and stasis during the early period of acute necrotizing pancreatitis (ANP) appears to be important to reduce the risks of secondary pancreatic infection. We aimed to characterize the association between the neuropathy of the enteric nervous system and gut dysfunction and to examine the effect of octreotide on motor innervation in the early stage of ANP.

Methodology/Principal Findings

The rats were randomly divided into eight groups: control+saline; control+octreotide; ANP+saline and ANP+octreotide (24 h, 48 h, 72 h). The spontaneous activity of ileal segments and the response to ACh, l-NNA were recorded. The alterations of myenteric neuronal nitric oxide synthase (nNOS), choline acetyltransferase (CHAT), PGP9.5 and somatostatin receptor 2 (SSTR₂) immunoreactive cells were evaluated by immunofluorescence and the protein expression of nNOS and CHAT were evaluated by western blot. We found the amplitude of spontaneous contractions at 48 h and the response to ACh at 24 h declined in the ANP+saline rats. A higher contractile response to both ACh and to l-NNA was observed in the ANP+octreotide group, compared with the ANP+saline rats at 24 h. A significant reduction in the nNOS and cholinergic neurons was observed in ANP+saline rats at the three time points. However, this reduction was greatly ameliorated in the presence of octreotide at 24 h and 48 h. The protein expression of CHAT neurons at 24 h and the nNOS neurons at 48 h in the ANP+octreotide rats was much higher than the ANP+saline rats.

Conclusion

The pathogenesis of ileus in the early stage of ANP may be related to the neuropathy of the enteric nervous system. Octreotide may reduce the severity of ileus by lessening the damage to enteric motor innervation.

Effect of an omega-3 lipid emulsion in reducing oxidative stress in a rat model of intestinal ischemia-reperfusion injury

OBJECTIVES

The usefulness of omega-3 lipid emulsions has been extensively studied. The objectives of the present study were to examine the effect of an omega-3 lipid emulsion in reducing oxidative stress in a rat model of intestinal ischemia-reperfusion injury and the underlying mechanism.

METHODS

A total of 66 rats were divided into three dietary groups (lipid-free, soybean oil, and fish oil groups). Each animal was administered total parenteral nutrition for 3 days, followed by induction of intestinal ischemia for 100 min. Animals subjected to sham surgery served as the controls. Intestinal tissue and blood were harvested 6 and 12 h after the surgery, then, assessment of the histological damage score, plasma-related parameters, and statistical evaluation were performed.

RESULTS

The histological damage score in the intestinal tissues was significantly lower in the fish oil group than in the soybean oil group (P = 0.0121). The late-phase urinary level of 8-hydroxy-2-deoxyguanosine was also significantly lower in the fish oil group as compared with that in the other groups (P = 0.0267). Furthermore, the plasma level of high-mobility group box 1 protein was also significantly lower in the fish oil group as compared with that in the lipid-free group (P = 0.0398).

CONCLUSION

It appeared that intravenous administration of an omega-3 lipid emulsion prior to ischemia-reperfusion injury reduced the oxidative stress and severity of tissue damage. Modification of membrane fatty acids may serve as the mechanism underlying this reduction of tissue damage.

Octreotide ameliorates intestinal dysmotility by interstitial cells of Cajal protection in a rat acute necrotizing pancreatitis model

OBJECTIVES

Intestinal motility is impaired in acute necrotizing pancreatitis (ANP). The aim of present study was to investigate the effects of octreotide on the small intestinal motor function during experimentally induced ANP.

METHODS

L-Ornithine was intraperitoneally injected to induce ANP. Octreotide was administrated subcutaneously every 8 hours. The small intestine migrating myoelectrical complexes and slow waves in vivo were recorded before and after (24, 48, and 72 hours) ANP induction. The morphological alterations of interstitial cells of Cajal (ICCs) in deep muscular plexus were evaluated by immunohistochemistry and Western blots.

RESULTS

Disturbed migrating myoelectrical complex cycle length and decreased dominant frequency of slow waves exacerbated gradually with time. The bolus applications of octreotide per 8 hours attenuated these functional abnormalities. The result of morphological study suggested that octreotide might ameliorate the damage of ICCs at 48 and 72 hours after ANP induction. Decreased expression of c-Kit protein at 72 hours was also attenuated by octreotide.

CONCLUSIONS

The pathogenesis of the ileus in ANP may be related to the sustained deficiencies in ICCs. Octreotide may ameliorate the severity of ileus by minimizing the injury of ICCs.

Pyloric atresia associated with Dieulafoy lesion and gastric dysmotility in a neonate

In this case study, we report a male infant with pyloric atresia, extreme gastric distension, and a caliber-persistent gastric artery (Dieulafoy lesion) with massive gastric bleeding. After a transverse pyloroplasty and endoscopic hemoclip application to the caliber-persistent gastric artery, very slow gastric emptying developed, which required repeated surgical interventions. Gastroduodenostomy failed to promote gastric emptying. The intraoperative and postmortem histologic examinations of the gastric wall revealed a loss of interstitial cells of Cajal, which possibly explains the extreme motility disorder.

Influence of immunosuppression on alloresponse, inflammation and contractile function of graft after intestinal transplantation

In small bowel transplantation (SBTx), graft manipulation, ischemia/reperfusion injury and acute rejection initiate a severe cellular and molecular inflammatory response in the muscularis propria leading to impaired motility of the graft. This study examined and compared the effect of tacrolimus and sirolimus on inflammation in graft muscularis. After allogeneic orthotopic SBTx, recipient rats were treated with tacrolimus or sirolimus. Tacrolimus and sirolimus attenuated neutrophilic, macrophage and T-cell infiltration in graft muscularis, which was associated with reduced apoptotic cell death. Nonspecific inflammatory mediators (IL-6, MCP-1) and T-cell activation markers (IL-2, IFN-gamma) were highly upregulated in allogeneic control graft muscularis 24 h and 7 days after SBTx, and tacrolimus and sirolimus significantly suppressed upregulation of these mediators. In vitro organ bath method demonstrated a severe decrease in graft smooth muscle contractility in allogeneic control (22% of normal control). Correlating with attenuated upregulation of iNOS, tacrolimus and sirolimus treatment significantly improved contractility (64% and 72%, respectively). Although sirolimus reduced cellular and molecular inflammatory response more efficiently after 24 h, contrary tacrolimus prevented acute rejection more efficiently. In conclusion, tacrolimus and sirolimus attenuate cellular and molecular inflammatory response in graft muscularis and subsequent dysmotility of the graft after allogeneic SBTx.

Damage of the interstitial cells of Cajal and myenteric neurons causing ileus in acute necrotizing pancreatitis rats

BACKGROUND

Small intestinal motility is impaired in acute necrotizing pancreatitis (ANP). The present study was designed to detect the impairment in small intestinal motility and to assess the role of interstitial cells of Cajal (ICC), myenteric neurons and the associated mechanism in the pathogenesis of ileus during experimentally induced acute pancreatitis.

METHODS

ANP was induced by intraperitoneal injections of 30% L-ornithine at a dose of 3 g/kg at hourly intervals. The alterations of small intestine electrical activity--migrating myoelectric complexes (MMCs), and slow waves--were measured 24 hr after ANP induction. The spontaneous mechanical activity and the contractile response to ACh, KCl, tetrodotoxin (TTX) and the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine (L-NNA) were evaluated by organ bath technique, and the morphologic alterations of the network of ICC, myenteric neurons and neuronal nitric oxide synthase (nNOS) immunoreactive cells were evaluated using the markers of c-Kit, PGP9.5, and nNOS, respectively. To demonstrate the deficiencies in enteric neuronal origin, we also measured nNOS expression in the muscular layer of ileum.

RESULTS

L-ornithine-induced necrotizing pancreatitis manifests with multiple symptoms, including decreased amplitude of spontaneous contractions in small intestinal smooth muscle, declined contractile response to ACh, TTX, and L-NNA in vitro, disrupted MMC cycle length, decreased dominant frequency and dominant power of slow waves in vivo. Furthermore, the morphologic studies demonstrated the damage of ICC (ANP group versus control; P = .000), myenteric neurons (ANP group versus control; P = .001) and nNOS immunoreactive neurons (ANP group versus control; P = .000). We also observed a substantial loss in the expression of nNOS protein in muscular layer of the small intestine (ANP group versus control; P = .032).

CONCLUSION

Our results suggest that the pathogenesis of the small intestinal paralysis in ANP may be related to the deficiencies in ICC and nNOS neurons.

Delayed gastric emptying and disruption of the interstitial cells of Cajal network after gastric ischaemia and reperfusion

BACKGROUND

Gastrointestinal tract is one of the most susceptible organ systems to ischaemia. Not only mucosal injury but also alterations of the intestinal motility and loss of interstitial cells of Cajal (ICC) have been reported in response to ischaemia and reperfusion (I/R). However, there are few reports on the changes in the gastric motility after gastric I/R. The present study was designed to investigate the alterations in gastric emptying, the ICC and enteric nerves that regulate smooth muscle function in response to gastric I/R.

METHODS

Seven-week-old male Wistar rats were exposed to gastric I/R, and the gastric emptying rates at 12 and 48 h after I/R were evaluated by the phenol red method. Expressions of gene product of c-kit receptor tyrosine kinase (c-Kit), a marker of ICC, and of neuronal proteins were also examined.

KEY RESULTS

Gastric emptying was transiently delayed at 12 h after I/R, but returned to normal by 48 h. Expression of c-Kit protein as assessed by Western blotting and immunofluorescent staining of the smooth muscle layer, as well as expression of the mRNA of stem cell factor, the ligand for c-Kit, were reduced at both 12 and 48 h after I/R. The expression of neuronal nitric oxide synthase (nNOS) protein as assessed by Western blotting and immunofluorescent staining was also decreased at 12 h after I/R, but was restored to normal by 48 h.

CONCLUSIONS & INFERENCES

Gastric I/R evokes transient gastroparesis with delayed gastric emptying, associated with disruption of the ICC network and nNOS-positive neurons.

The reactions of specific neuron types to intestinal ischemia in the guinea pig enteric nervous system

Damage following ischemia and reperfusion (I/R) is common in the intestine and can be caused during abdominal surgery, in several disease states and following intestinal transplantation. Most studies have concentrated on damage to the mucosa, although published evidence also points to effects on neurons. Moreover, alterations of neuronally controlled functions of the intestine persist after I/R. The present study was designed to investigate the time course of damage to neurons and the selectivity of the effect of I/R damage for specific types of enteric neurons. A branch of the superior mesenteric artery supplying the distal ileum of anesthetised guinea pigs was occluded for 1 h and the animals were allowed to recover for 2 h to 4 weeks before tissue was taken for the immunohistochemical localization of markers of specific neuron types in tissues from sham and I/R animals. The dendrites of neurons with nitric oxide synthase (NOS) immunoreactivity, which are inhibitory motor neurons and interneurons, were distorted and swollen by 24 h after I/R and remained enlarged up to 28 days. The total neuron profile areas (cell body plus dendrites) increased by 25%, but the sizes of cell bodies did not change significantly. Neurons of type II morphology (intrinsic primary afferent neurons), revealed by NeuN immunoreactivity, were transiently reduced in cell size, at 24 h and 7 days. These neurons also showed signs of minor cell surface blebbing. Calretinin neurons, many of which are excitatory motor neurons, were unaffected. Thus, this study revealed a selective damage to NOS neurons that was observed at 24 h and persisted up to 4 weeks, without a significant change in the relative numbers of NOS neurons.

Bombesin can minimize impairments of interstitial cells of Cajal induced by FK506 in small bowel transplantation

PURPOSE

Interstitial cells of Cajal (ICC) are known as intestinal pacemaker cells and express c-kit on their membrane. Previously, we reported that FK506 had neurotoxicity to enteric ganglia, and bombesin (BBS) preserved them against FK506. The aim of this study was to investigate whether ICC was impaired by FK506 and whether ICC was preserved by BBS against FK506.

METHODS

Twelve rats underwent allogeneic SBTx heterotopically and were divided into 2 groups as follows: group A underwent SBTx with FK506 and group B with FK506/BBS. All rats were administered FK506 daily. Either BBS or normal saline was infused continuously from day 14 to 28. Analysis of ICC was performed immunohistochemically with c-kit. Interstitial cells of Cajal were evaluated by counting the number of c-kit-positive clusters in each graft.

RESULTS

The expression of c-kit accumulated around 60% of PGP9.5-positive enteric ganglia. The number of c-kit-positive clusters in group A was 22.3 +/- 5.5 clusters per cross section (C/CS) and that in group B was 36.3 +/- 5.1 C/CS. Interstitial cells of Cajal were well preserved in group B. There was a significant difference between groups A and B (P <.001).

CONCLUSION

Interstitial cells of Cajal were impaired by FK506 in allografts, and BBS could minimize the impairment of ICC against FK506.

The effects of intestinal ischemia on colonic motility in conscious rats

BACKGROUND

The present study aimed to examine whether and how colonic motility is affected by mild ischemia-induced intestinal injury in conscious rats through in vivo monitoring of colonic contractions, specifically with regard to the interstitial cells of Cajal (ICC) and the effect of nitric oxide (NO).

METHODS

Using miniature strain-gauge transducers, colonic motility with or without ischemia was recorded in conscious rats on the 4th, 7th, and 14th days after surgery. Histological examination for c-kit-positive cells was performed.

RESULTS

In control nonischemic rats, the number and duration of contractions (NC and DC, respectively) decreased gradually, but the mean amplitude of contractions (MC) and motility index (MI) did not change. On the 7th day, the NC in the ischemic group increased significantly when compared with that in the control group (P = 0.037). The DC in the ischemic group was lower than that in the control group; the difference was significant on the 4th day (P = 0.008). The MIs in the ischemic group were lower than those in the control group. In both groups, administration of NGnitro-L: -arginine methyl ester on the 7th day increased only the resting cecal motility. Pathological examinations revealed c-kit-positive cells in both groups.

CONCLUSIONS

Changes such as increased NC with shortened DC accompanied with decreased MI must have occurred at the ischemic site and might have been induced by an ischemic event. However, there exists a possibility that ICC and NO do not play a role in mild ischemia-induced dysmotility.

Infiltration of mast cells in rat colon is a consequence of ischemia/reperfusion

Intestinal ischemia as well as mastocytosis occur in patients with inflammatory bowel disease and irritable bowel syndrome. Our aim was to clarify how ischemia with reperfusion (I/R) affects the structure, enteric neurons, and immune cells in the colon. Rats were subjected to colon ischemia for 1 h and reperfused for 1 day up to 20 weeks; sham-operated rats were used as controls. No structural remodeling of the intestinal segment was detected after I/R. The number and distribution of eosinophils were not affected by I/R. Local areas containing numerous mast cells were detected in the muscle layers, the serosa, and in and around the myenteric ganglia 4-20 weeks post ischemia. It was notable that myenteric ganglionic formations within mast-cell-rich areas virtually lacked neurons. Mast cells were rarely found in controls. In conclusion, I/R of the colon attracts mast cells, and death of myenteric neurons occurs in such locations.

Oxymatrine attenuates intestinal ischemia/reperfusion injury in rats

PURPOSE

Intestinal ischemia/reperfusion (I/R) is a common and serious clinical condition. The anti-inflammatory and anti-apoptotic properties of oxymatrine, the extract from a traditional Chinese herb, Sophora flavescens Ait, have been shown to protect the liver from I/R injury and attenuate colitis. The objective of this study was to investigate if oxymatrine could attenuate intestinal I/R injury induced in rats.

METHODS

The experimental design consisted of three groups of 24 Wistar rats each: a sham-operation group (control group), a group subjected to intestinal I/R and then given saline (saline group), and a group subjected to intestinal I/R and then given oxymatrine (oxymatrine group). Intestinal I/R was induced by occluding the superior mesenteric artery for 45 min. Six rats from each group were killed at selected time points, and blood and intestinal samples were collected.

RESULTS

Morphological alteration, reduction of gamma-glutamyl transpeptidase (gamma-GGT) activity, and increased cell apoptosis confirmed intestinal I/R injury. The oxymatrine group had a significantly lower histological score and apoptosis index than the saline group, demonstrating that the preadministration of oxymatrine attenuated gut damage. Moreover, oxymatrine inhibited the production of lipid peroxides (LPO), decreased the serum levels of tumor necrosis factor (TNF)-alpha, and downregulated expression of phosphorylated p38 mitogen-activated protein kinase, Fas, and FasL, which had been elevated by I/R.

CONCLUSIONS

These results provide further evidence of the anti-inflammatory and anti-apoptotic activities of oxymatrine, which may become a potent drug for protecting the intestines against I/R injury.

Correlation of motility and neuronal integrity with a focus on the grade of intestinal allograft rejection

Intestinal graft motility after small bowel transplantation (SBT) is poorly characterized. The aim of this study was to compare motor patterns with myenteric neuronal cell population as a parameter of graft viability at various degrees of acute cellular rejection (ACR). Three grades of ACR were achieved in orthotopic allografts. Syngeneic transplants and allografts with immunosuppression served as controls. Motor activities were recorded using strain gauge force transducers and analyzed visually. Quantifications of myenteric neurons in whole mounts of intestinal grafts were used to evaluate neuronal population. A typical migrating motor complex (MMC) was found in syngeneic and allogenic transplants with immunosuppression. A high prevalence of discrete clustered contractions (DCC) and nonpropagating contractions (NPC) without MMC was seen in moderately and severely rejected allografts. Neuronal cell loss in the allografts, which could be one of the causes of motor dysfunction, was noted in moderate rejection (19.3%) and progressed until severe rejection (60.1%). Monitoring motility patterns in SBT could be an effective tool for assessing intestinal rejection. Allograft dysmotility, such as absence of MMC and high prevalence of DCC or NPC, could be useful markers of progression of acute rejection and help guide treatment decisions.

Morphological and physiological changes of interstitial cells of Cajal after small bowel transplantation in rats

Intestinal dysmotility has been reported to be associated with a decreased number of interstitial cells of Cajal (ICCs). However, the chronological changes in ICCs after small bowel transplantation (SBT) have not yet been elucidated. In this study, we aimed to evaluate the chronological change of ICCs after SBT. Orthotopic syngeneic SBT was performed in rats. Graft specimens were obtained at postreperfusion, and on 1, 3, 7, 14, and 30 postoperative day (POD). Thereafter, immunohistochemical staining was performed and the spontaneous contractions measured. During the initial period after SBT, the temporal impairment of ICCs was found. In an immunohistochemical study, c-Kit-positive cells appeared to decrease on POD 0, 1, and 3. Thereafter, the number of cells increased gradually up to POD 7. In contrast, the recovery of the spontaneous contractile amplitude took more time. The frequency of the electrical signal was preserved at almost exactly the same levels throughout this experimental period. Although the network of ICCs was found to be temporarily impaired after SBT in an immunohistochemical examination, this change was reversible. Moreover, the recovery of the function of the intestinal motility associated with ICCs was delayed after the early postoperative period.

Interstitial Cajal-like cells in rat mesentery: an ultrastructural and immunohistochemical approach

Interstitial Cajal-like Cells (ICLC) were recently recognized in a plethora of non-digestive organs. Here, we describe a cell type of rat mesentery sharing ultrastructural and immunohistochemical features with ICLC. Mesenteric ICLC were demonstrated by transmission electron microscopy (TEM) and further tested by light microscope immunohistochemistry. The cell described here fulfils the TEM diagnostic criteria accepted for ICLC: location in the connective interstitium; close vicinity to nerves, capillaries and other interstitial cells; characteristic long, moniliform cell processes; specialized cell-to-cell junctions; caveolae; mitochondria at 5–10% of cytoplasmic volume; rough endoplasmic reticulum at about 1–2%; intermediate and thin filaments, microtubules; undetectable thick filaments. The processes of this mesenteric ICLC were particularly long, with a mean length of 24.91 μm (10.27–50.83 μm), and a convolution index of 2.32 (1.37–3.63) was calculated in order to measure their potential length. Mean distances versus main target cells of ICLC–nerve bundles, vessels, adipocytes and macrophages–were 110.69, 115.80, 205.07 and 34.65 nm, respectively. We also tested the expression of CD117/c-kit, CD34, vimentin, α-smooth muscle actin, nestin, NK-1, tryptase and chymase and the antigenic profile of the mesenteric ICLC was comparable if not identical with that recently observed in ICLC from other extra-digestive tissues. Due to the peculiar aspect of the mesenteric ICLC processes it can be hypothesized that these cells form a three-dimensional network within the mesentery that is at the same time resistant and deformable following stretches consequent to intestine movements, mainly avoiding blood vessels closure or controlling blood vessels rheology. It remains, however, to be established if and how such cells are connected with the archetypal enteric ICC.