Pirfenidone prevents rat esophageal stricture formation

A Novel Rat Model to Simulate the Benign Esophageal Stricture Induced by Endoscopic Submucosal Dissection

Objective

This study aimed to establish a rat model that simulates benign esophageal strictures induced by endoscopic submucosal dissection (ESD).

Materials and Methods

Sixteen male Sprague-Dawley rats were randomly divided into mucosal resection (n = 8) and sham-operated groups (n = 8). The rats in the mucosal resection group underwent a 5-mm three-fourths mucosal resection by way of a 3-mm incision in the distal esophagus under direct visualization via laparotomy. Rats in the sham-operated group underwent a 3-mm incision of the muscularis propria layer in the distal esophagus via laparotomy without mucosal resection. Dysphagia score, weight gain, mucosal constriction rate, and histology were evaluated 2 weeks after surgery.

Results

Technical success was achieved in all the animals. One rat in the mucosal resection group died of infection, and no other complications were observed. Weight gain (P < 0.001) and luminal diameter derived from the esophagograms (P < 0.001) were significantly lower in the mucosal resection group than those in the sham-operated group. Dysphagia score (P < 0.001) and mucosal constriction rate (P < 0.001) were significantly higher in the mucosal resection group than those in the sham-operated group. The inflammation grade (P = 0.002), damage to the muscularis propria (P < 0.001), number of nascent microvessels (P = 0.006), and degree of α-SMA positive deposition (P = 0.006) were significantly higher in the mucosal resection group.

Conclusion

A rat model of benign esophageal stricture induced by ESD was successfully and safely established by mucosal resection.

Pirfenidone prevents esophageal stricture by inhibiting nucleotide binding oligomerization domain like receptor protein 3 inflammasome activation

BACKGROUND AND AIM

Esophageal injury often results in a scar, leading to refractory strictures. The NLRP3 inflammasome activates caspase-1, causing the maturation of interleukin (IL)-1β. Here, we aimed to investigate the preventive effect of pirfenidone (PFD), an antifibrotic drug, on esophageal stricture after ulcer healing and studied its mechanism by focusing on the activation of the NLRP3 inflammasome.

METHODS

Esophageal ulcers were induced in rats via the local application of acetic acid in the serosa. PFD was intraperitoneally administered to the rats 3 days after ulcer induction. The effect of PFD on esophageal stricture after ulcer healing was assessed by esophagography on day 9. The protein levels of mature caspase-1 and IL-1β were assessed by western blotting.

RESULTS

The ulcers fully developed 3 days after induction and were almost scarred by day 9 with severe strictures. PFD promoted ulcer healing and attenuated fibrotic collagen in the submucosa by suppressing the increase in NLRP3, cleaved caspase-1, and mature IL-1β expression, improving stricture rate (PFD vs vehicle = 55% vs 81%). Exogenous IL-1β abolished the therapeutic effects of PFD on ulcer healing and stricture formation. Furthermore, NLRP3 and caspase-1 inhibitors mimicked the effects of PFD on ulcer healing and stricture formation, with suppression of the increase in cleaved caspase-1 and mature IL-1β proteins and expression of fibrosis-related molecules including transforming growth factor (TGF)-β1.

CONCLUSION

The NLRP3 inflammasome promotes esophageal stricture formation following ulcer healing, and PFD exerts potential prophylactic activity against strictures, possibly via the inhibition of the NLRP3/IL-1β/TGF-β1 axis.

Cordycepin prevents the esophageal stricture formation in the alkali-burn rat model by exerting anti-inflammatory and antifibrotic effects

Purpose

To investigate the efficacy of cordycepin, an adenosine analogue, on prevention of esophageal damage and stricture formation due to esophageal caustic burns in rat model comparing with prednisolone.

Methods

Caustic esophageal burn was introduced by 37.5% of NaOH to distal esophagus. Thirty-two Wistar albino rats were divided in four groups: sham rats undergone laparotomy, treated with 0.9% NaCl; control rats injured with NaOH without cordycepin treatment; cordycepin group injured with NaOH, treated with 20 mg/kg cordycepin; prednisolone group injured with NaOH, treated with 1 mg/kg prednisolone for 28 days. Efficacy was assessed by histopathological and immunohistochemical analysis of esophageal tissues.

Results

Cordycepin treatment significantly decreased inflammation, granulation tissue and fibrous tissue formation and prevented formation of esophageal strictures shown by histopathological damage score and stenosis indexes compared to control group (p < 0.01). These effects are relatively more substantial than prednisolone, probably based on attenuation of elevation of proinflammatory cytokines hypoxia-inducible factor 1-alpha (HIF-1?), tumor necrosis factor alpha (TNF-?), proliferative and fibrotic factor fibroblast growth factor 2 (FGF2) and angiogenic factor vascular endothelial growth factor A (VEGFA) (p < 0.05).

Conclusions

The findings suggest that cordycepin has a complex multifactorial healing process in alkali-burned tissue, more successful than prednisolone in preventing the formation of esophageal strictures and may be used as a therapeutic agent in the acute phase of esophageal alkali-burn.

Effects of Carvacrol in an Experimentally Induced Esophageal Burn Model: Expression of VEGF and Caspase-3 Proteins

INTRODUCTION

We investigated the therapeutic effects of carvacrol in an experimental esophageal burn rat model with immunohistochemical techniques. Materials and Methods: Three groups were included in this study, composed of eight Wistar albino rats each. The control group was given 1 mL 0.9% (wt/vol) NaCl; esophageal burns were induced in groups 2 and 3 by administration of 1 mL 40% NaOH in the distal 2 cm of the esophagus. The treatment group was administered 75 mg/kg carvacrol in 2 mL 0.9% NaCl for 10 days. After a routine histological examination of the tissues, sections were stained with vascular endothelial growth factor (VEGF) and caspase-3 for immunohistochemical analysis and were examined under a light microscope. Results: In the control group, there were regular cells in the cornified epithelial tissue and cylindrical cells in the basal layer, which faced toward the apical surface in the mitotic phase. The burn group displayed wide degeneration, necrosis, and abundant apoptotic cells in the epithelial tissue as well as intense inflammatory cell infiltration. In the treatment group, there was an increase in mitotic activity in the basal cells of the epithelial layer and degenerative changes, but a preserved epithelial layer and significant cornified structures. The treatment group showed positive caspase-3 expression in some apoptotic cells within the epithelial layer and in connective tissue, and there were only a small number of degenerated cells in the muscle layer. Additionally, in the treatment group, VEGF expression was evident in small numbers of inflammatory cells in the papillary region of the epithelium, and in dilated vascular endothelial cells. Conclusions: Carvacrol may contribute to a reduction in fibrosis by decreasing inflammation and preventing cell apoptosis.

A Novel Rabbit Model for Benign Biliary Stricture Formation and the Effects of Medication Infusions on Stricture Formation

BACKGROUND

Benign biliary stricture (BBS) is highly refractory. Currently, there is no effective strategy for prevention of BBS recurrence. The aim of this study is to establish a novel BBS rabbit model and to investigate the efficacy of biliary infusion with anti-proliferative medications for treating BBS.

METHOD

A BBS model was established via surgical injury and biliary infection. The biliary infusion tube was inserted into the common bile duct via the stump of cystic duct after cholecystectomy. Biliary infusions with Rapamycin, Pirfenidone and Fasudil were performed daily during the 4 weeks following the surgery. The wall thickness and luminal area of the bile duct were assessed.

RESULTS

All rabbits formed BBS after surgery. The mortality rate was 13% (8/60) and tube withdrawal rate was 4% (2/48). The thickness of the bile duct wall was significantly reduced; whereas the luminal area of the bile duct was dramatically enlarged in the Rapamycin or the Pirfenidone treated group, compared to the saline treated group. Furthermore, the local treatment significantly decreased the levels of proliferation makers, including PCNA, Collagen I and fibrogenic mediators, including ACTA2 and TGF-beta.

CONCLUSION

We have established a novel animal model for BBS formation. We have further demonstrated that biliary infusion with Rapamycin or Pirfenidone limits the biliary strictures through inhibiting the proliferation of the bile duct wall in this model. This may represent a new avenue for preventing biliary restenosis.

Pirfenidone reduces subchondral bone loss and fibrosis after murine knee cartilage injury

Pirfenidone is an anti-inflammatory and anti-fibrotic drug that has shown efficacy in lung and kidney fibrosis. Because inflammation and fibrosis have been linked to the progression of osteoarthritis, we investigated the effects of oral Pirfenidone in a mouse model of cartilage injury, which results in chronic inflammation and joint-wide fibrosis in mice that lack hyaluronan synthase 1 (Has1^-/- ) in comparison to wild-type. Femoral cartilage was surgically injured in wild-type and Has1^-/- mice, and Pirfenidone was administered in food starting after 3 days. At 4 weeks, Pirfenidone reduced the appearance, on micro-computed tomography, of pitting in subchondral bone at, and cortical bone surrounding, the site of cartilage injury. This corresponded with a reduction in fibrotic tissue deposits as observed with gross joint surface photography. Pirfenidone resulted in significant recovery of trabecular bone parameters affected by joint injury in Has1^-/- mice, although the effect in wild-type was less pronounced. Pirfenidone also increased Safranin-O staining of growth plate cartilage after cartilage injury and sham operation in both genotypes. Taken together with the expression of selected extracellular matrix, inflammation, and fibrosis genes, these results indicate that Pirfenidone may confer chondrogenic and bone-protective effects, although the well-known anti-fibrotic effects of Pirfenidone may occur earlier in the wound-healing response than the time point examined in this study. Further investigations to identify the specific cell populations in the joint and signaling pathways that are responsive to Pirfenidone are warranted, as Pirfenidone and other anti-fibrotic drugs may encourage tissue repair and prevent progression of post-traumatic osteoarthritis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:365-376, 2018.

Effect of polaprezinc on experimental corrosive esophageal burns in rats

Unconsciously caustic ingestion is one of the most common causes of serious esophageal strictures in children. The aim of this study is to determine the efficiency of polaprezinc in preventing stricture formation after corrosive esophageal burns (CEB); this was the first time it has been used to treat experimental CEB in rats. Twenty-four rats were divided into four groups, three of which received CEB by the instillation of 1 mL of 10% NaOH solution into their isolated esophageal segments for three minutes. Group C (control) was uninjured and untreated. Group B (esophageal burn) received CEB but were left untreated. Groups PT1 and PT2 had CEB and received 100 mg/kg/day and 200 mg/kg/day, respectively, of intraperitoneal polaprezinc treatment (PT) for the first two weeks, then oral PT for another two weeks. We assessed the treatment's efficiency of the treatment after the fourth week by evaluating the stenosis index (SI) and the histopathological damage score, determining tissue hydroxyproline content (HP), and measuring the weight of the rats before and after the experiment. Mean SI was statistically lower in the groups PT1 and PT2 when compared with Group B (p = 0.006, 0.004, respectively). HP levels were highest in Group B, but it was insignificant (P> 0.05). In terms of histopathological damage score, treatment groups demonstrated less collagen deposition, mucosal, and submucosal damage than both Group B (p = 0.01) and Group C (p = 0.02). Group PT1 and Group PT2 (P> 0.05) showed similar results, indicating the treatment's effectiveness was independent of dosage. Outside of Group C, weight gain was detected only in Group PT2, though it was statistically insignificant. In Group PT1, weight loss was lower than in Group B. Polaprezinc, with its antifibrotic, antioxidant, anti-inflammatory, wound-healing and antiapoptotic effects, was efficient in reducing stricture formation by decreasing HP levels and histopathologic damage, preventing stenosis, and weight gain in higher dosages in the treatment group.

EW-7197, an activin-like kinase 5 inhibitor, suppresses granulation tissue after stent placement in rat esophagus

BACKGROUND AND AIMS

Self-expanding metallic stent (SEMS) placement is a well-established method for treating malignant esophageal strictures; however, this procedure has not gained widespread acceptance for treating benign esophageal strictures because of granulation tissue formation. The aim of the present study was to investigate whether EW-7197, a novel per-oral transforming growth factor-β type I receptor kinase inhibitor, suppressed granulation tissue formation after SEMS placement in the rat esophagus.

METHODS

Sixty rats underwent SEMS placement and were randomly divided into 4 groups. Group A (n = 20) received vehicle-treated control for 4 weeks. Group B (n = 20) received 20 mg/kg/day EW-7197 for 4 weeks. Group C (n = 10) received 20 mg/kg/day EW-7197 for 4 weeks followed by vehicle-treated control for 4 weeks. Group D (n = 10) received 20 mg/kg/day EW-7197 for 8 weeks.

RESULTS

SEMS placement was technically successful in all rats. Eleven rats, however, were excluded because of stent migration (n = 9) and procedure-related death (n = 2). The luminal diameter in group A was significantly smaller than those in groups B, C, and D (all P < .001). The percentage of granulation tissue area, number of epithelial layers, thickness of submucosal fibrosis, percentage of connective tissue area, and degree of collagen deposition were significantly higher in group A than in groups B, C, and D (all P < .001); however, there were no significant differences among groups B, C, and D. EW-7197 decreased the expression levels of phospho-Smad 3, N-cadherin, fibronectin, α-smooth muscle actin, and transforming growth factor-β1 and increased the expression level of E-cadherin (all P < .01).

CONCLUSIONS

EW-7197 suppressed granulation tissue formation after SEMS placement in the rat esophagus.

Caustic ingestion in children-A review

Various domestic or industrial chemicals may cause significant upper aerodigestive tract burns. Preventive measures should be up-scaled, especially in the developing world, to reduce the epidemic of accidental victims, largely unsupervised preschool children. External signs do not predict degree of injury. Non-invasive diagnostic screening includes radio-nuclear imaging, but early oesophago-gastroduodenoscopy remains the standard to predict stricture formation from circumferential submucosal scarring. Serial dilation is the mainstay of oesophageal stricture therapy, with oesophageal replacement reserved for severe refractory strictures. Intra-lesional steroid or mitomycin C may decrease the dilatations required for severe strictures, although long-term effects are unknown. Risk of secondary oesophageal carcinoma mandates long-term surveillance.

In Vivo Endoluminal Ultrasound Biomicroscopy and Endoscopy of Inflamed Rat Esophagus

The development of high-frequency endoscopic ultrasound for the investigation of models of esophageal disease may offer insights for future translation to human imaging. With respect to small animal models of esophageal diseases, ultrasound imaging instrumentation must employ frequencies scaled up to maintain the compromise between image resolution and inspected region. In this sense, a 40-MHz endoluminal ultrasound biomicroscopy (eUBM) system and an endoscope were tested as diagnostic methods of imaging rat esophageal lesions in the acute and chronic phases caused by sodium hydroxide. Although endoscopy allowed grading of the esophagus in accordance with a classification specific to the epithelial alterations and including hyperemia, edema, exudates, fibrin and superficial and deep ulcerations, the eUBM images yielded the detection of superficial and deep ulcerations, as well as wall alterations caused by edema and inflammatory infiltrate in the submucosa. Additionally, eUBM enabled wall thickness measurements, which were statistically significantly increased (p < 0.05) in the acute phase.