Time-Dependent Alterations of Gut Wall Integrity in Small Bowel Obstruction in Mice

Heterozygous Actg2R257C mice mimic the phenotype of megacystis microcolon intestinal hypoperistalsis syndrome

BACKGROUND

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a rare and serious congenital disorder with poor outcomes, where a heterozygous missense mutation is present in the ACTG2 gene. Here, we aimed to investigate the pathogenesis of ACTG2 in MMIHS.

METHODS

A cohort with 20 patients with MMIHS was screened. Actg2^R257C heterozygous mutant mice were generated using the CRISPR/Cas9 system. Gastrointestinal (GI) motility, voluntary urination, collagen gel contraction, and G-actin/F-actin analysis were performed.

KEY RESULTS

The R257C variant of ACTG2 most frequently occurred in patients with MMIHS and demonstrated the typical symptoms of MMIHS. Actg2^R257C heterozygous mutant mice had dilated intestines and bladders. The functional assay showed a prolonged total time of GI transit and decreased urine spot area. Collagen gel contraction assay and G-actin/F-actin analysis indicated that mutant mice showed reduced area of contraction of smooth muscle cells (SMCs) and impaired actin polymerization.

CONCLUSIONS & INFERENCES

A mouse model demonstrating MMIHS-like symptoms was generated. The Actg2^R257C heterozygous variant impairs SMCs contraction by interfering with actin polymerization, leading to GI motility disorders.

Glycyrrhiza Polysaccharide Alleviates Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice

Background

Licorice is one of the most ubiquitous herbs in traditional Chinese medicine, with notable anti-inflammatory and antiulcerative effects as well as potent digestive disease therapeutic impacts; yet, its active components and mechanisms remain unclear. There is a lot of evidence that Glycyrrhiza polysaccharide (GPS) has antioxidants, improving intestinal flora, anti-inflammatory effects, etc. Hypothesis/Purpose. Here, we investigated the effects of GPS on dextran sulfate sodium (DSS)-induced acute ulcerative colitis (UC) mice and its possible mechanisms.

Methods

GPS (100, 200, and 400 mg/kg) or the positive control drug sulfasalazine (SASP) (200 mg/kg) were orally administered to mice for 8 days. Body weight was recorded daily. Symptoms associated with UC, such as disease activity index (DAI), colon length, spleen weight, and mucosal damage were detected. The possible mechanism of GPS ameliorating enteritis symptoms was explored by detecting intestinal permeability and serum levels of inflammatory factors, and changes in intestinal permeability were expressed by serum concentration of FITC-dextran and D-lactic acid.

Results

The results demonstrated that GPS administration alleviated UC symptoms in colitis mice, including weight loss, DAI index, shorting colon length, and mucosal damage. Mechanistic evaluation revealed that GPS treatment reduced intestinal permeability and serum levels of inflammatory factors: IL-1, IL-6, and TNF-α, while increasing serum levels of the anti-inflammatory factor IL-10, suggesting that GPS's mechanism in UC is related to reducing intestinal permeability and inhibiting the inflammatory response, with intestinal permeability implicated as the initiating mechanism.

Conclusion

This study highlights GPS as a promising therapeutic agent, with high therapeutic efficacy and a good safety profile, for enteritis and beyond.

Pneumatosis intestinalis and portal venous gas in mechanical small bowel obstruction: Is it worrisome?

PURPOSE

The purpose of this study was to evaluate the clinical significance of pneumatosis intestinalis (PI) and portal venous gas (PVG) in patients with mechanical small bowel obstruction (SBO), using surgical findings or clinical follow-up as standard of reference.

MATERIALS AND METHODS

Fourteen patients with mechanical SBO associated with PI and PVG were retrospectively included. There were 7 men and 7 women with a mean age of 59±19 (SD) (range: 25-93 years). CT examinations were reviewed by two radiologists to confirm the diagnosis of mechanical SBO and make a description of PI. Interobserver agreement was calculated. The reference standard was intraoperative appearance of the bowel wall (10/14; 71%) or the recovery of a normal bowel function in patients who were managed conservatively (4/14; 29%).

RESULTS

Among the 10 patients who underwent surgery, a normal appearance of the bowel in association with PI on CT was found intraoperatively in 8/10 (80%) patients and a reversible ischemia in the remaining 2/10 (20%) patients. The four patients who were managed conservatively recovered normal bowel function. Two patients died within two weeks following SBO.

CONCLUSION

PI and PVG are not specific signs of bowel necrosis in mechanical SBO.