Intraperitoneal insufflation of carbon dioxide rescues intestinal damage in an experimental murine model of colitis

OBJECTIVES

Necrotizing enterocolitis (NEC) is a severe neonatal surgical condition, associated with a prolonged pro-inflammatory state, leading to high mortality and morbidity rates. Carbon dioxide (CO2 ) insufflation during laparoscopy may have an anti-inflammatory effect. We aimed to evaluate the effects of CO2 -insufflation on experimental colitis.

METHODS

Acute colitis was induced in 6-week-old Balb/c mice by the administration of 2%-dextran sulfate-sodium (DSS) during 7 days (n = 45). On Day 4, two groups received intraperitoneal insufflation (duration: 30 mn, pressure: 5 mmHg) of CO2 ("DSS+CO2 ") or air ("DSS+air"). A group received no insufflation ("DSS"). Groups were compared for clinical severity using the disease activity index (DAI-body weight loss, stool consistency, and bleeding), histological severity (histopathological activity index, colon length, and ulcerations), colonic mucosecretion, and inflammation.

RESULTS

DAI was significantly decreased in DSS+CO2 group, compared to DSS (p < 0.0001) or DSS+air (p < 0.0001) groups. Colon length was increased in DSS+CO2 treated mice compared to DSS (p = 0.0002). The histopathological activity index was lower in DSS+CO2 (vs. DSS, p = 0.0059/vs. DSS+air, p = 0.0389), with decreased ulcerations (3.77 vs. 10.7, p = 0.0306), and persistent mucosecretion with increased mucin-secreting cells.

CONCLUSIONS

CO2 -insufflation attenuates DSS-induced colitis and improves both clinical and histological scores. Laparoscopy with CO2 insufflation represents a therapeutic anti-inflammatory strategy for NEC.

Usefulness of serum procalcitonin and point-of-care multiplex PCR gastro-intestinal panel in acute diarrhea or colitis in the emergency department

Introduction: Acute infectious diarrhea is one of the most common diseases worldwide. Procalcitonin (PCT) is useful for antibiotic stewardship in lower respiratory tract infections but has been poorly studied in infectious diarrhea. Our objective is to describe the PCT concentrations according to diarrhea etiology.Methods: This is a single-center prospective cohort study involving adults consulting the emergency department (ED) for an acute diarrhea or colitis. Serum PCT was measured and a stool sample was tested with FilmArray® Gastro-Intestinal Panel. The primary endpoint is the PCT concentration according to each type of pathogen identified using Gastro-Intestinal-panel and/or stool cultures at ED admission.Results: 125 patients were included: 80 had an acute infectious diarrhea, 21 an acute colitis and 24 another illness causing diarrhea. The median (interquartile ranges) PCT values (ng/ml) were 0.13 (0.08-0.28), 0.07 (0.06-0.54), 0.13 (0.09-0.26) and 0.05 (0.03-0.17), respectively if there was a bacteria (n = 41), parasite (n = 3), virus (n = 10) or no pathogen identified and 0.34 (0.13-1.03) if the diarrhea was due to another illness (n = 24).Conclusion: In patients admitted to the ED with an acute infectious diarrhea or acute colitis, PCT remained low when a bacteria was identified. It may not be informative in current practice to guide antibiotic therapy.

AKR1B8 deficiency drives severe DSS-induced acute colitis through invasion of luminal bacteria and activation of innate immunity

Background

Dysfunction of intestinal epithelial cells (IECs) promotes inflammatory bowel disease (IBD) and associated colorectal cancer (CRC). AKR1B8 deficiency impairs the IEC barrier function, leading to susceptibility to chronic colitis induced by dextran sulfate sodium (DSS), yet it remains unclear how acute colitic response is in AKR1B8 deficient mice.

Methods

AKR1B8 knockout (KO) and littermate wild type mice were exposed to oral 1.5% DSS in drinking water for 6 days. Disease activity index and histopathological inflammation scores by H&E staining were calculated for colitic severity; permeability was assessed by fluorescein isothiocyanate dextran (FITC-Dextran) probes and bacterial invasion and transmission were detected by in situ hybridization in mucosa or by culture in blood agar plates. Immunofluorescent staining and flow cytometry were applied for immune cell quantification. Toll-like receptor 4 (TLR4) and target gene expression was analyzed by Western blotting and qRT-PCR.

Results

AKR1B8 KO mice developed severe acute colitis at a low dose (1.5%) of DSS in drinking water compared to wild type controls. In AKR1B8 KO mice, FITC-dextran was penetrated easily and luminal bacteria invaded to the surface of IEC layer on day 3, and excessive bacteria translocated into the colonic mucosa, mesenteric lymph nodes (MLNs) and liver on day 6, which was much mild in wild type mice. Hyper-infiltration of neutrophils and basophils occurred in AKR1B8 KO mice, and monocytes in spleen and macrophages in colonic mucosa increased markedly compared to wild type mice. TLR4 signaling in colonic epithelial cells of AKR1B8 KO mice was activated to promote great IL-1β and IL-6 expression compared to wild type mice.

Conclusions

AKR1B8 deficiency in IECs drives severe acute colitis induced by DSS at a low dose through activation of the innate immunity, being a novel pathogenic factor of colitis.

Computer-Aided Screening and Revealing Action Mechanism of Food-Derived Tripeptides Intervention in Acute Colitis

Food-derived tripeptides can relieve colitis symptoms; however, their alleviation mode has not been systematically evaluated as an alternative nutritional compound. This study aimed to reveal the potential mechanism of 8000 food-derived tripeptides against acute colitis using a computer-aided screening strategy. Forty-one potential hub targets related to colitis with a Fit score > 4.0 were screened to construct the protein-protein and protein-tripeptide network based on the PharmMapper database and STRING software (Ver. 11.5). In addition, 30 significant KEGG signaling pathways with p-values < 0.001 that the 41 hub targets mainly participated in were identified using DAVID software (Ver. 6.8), including inflammatory, immunomodulatory, and cell proliferation and differentiation-related signaling pathways, particularly in the Ras- and PI3K-Akt signaling pathways. Furthermore, molecular docking was performed using the Autodock against majorly targeted proteins (AKT1, EGFR, and MMP9) with the selected 52 tripeptides. The interaction model between tripeptides and targets was mainly hydrogen-bonding and hydrophobic interactions, and most of the binding energy of the tripeptide target was less than −7.13 kcal/mol. This work can provide valuable insight for exploring food-derived tripeptide mechanisms and therapeutic indications.

Polyphenolic Extracts of Coffee Cherry Husks Alleviated Colitis-Induced Neural Inflammation via NF-κB Signaling Regulation and Gut Microbiota Modification

Coffee cherry husks, the main byproduct of coffee production, contain an abundance of polyphenols. In this study, dextran sodium sulfate (DSS)-induced colitis mice were used to study the protective effects of polyphenolic extracts of coffee cherry husks (CCHP) on inflammation. The results indicated that CCHP administration alleviated the histological changes of DSS-induced colitis in mice and downregulated the mRNA level of TNF-α, IL-1β, IL-6 and Cox-2. Interestingly, CCHP inhibited the activation of microglia and suppressed neural inflammation in the brain. The TLR4/Myd88/NF-κB signaling pathway was examined and found to be inhibited by CCHP. Furthermore, a determination of the gut microbiota showed that an alteration of microbiota induced by DSS was restored by CCHP, including the decrease of the relative abundance of Proteobacteria and the increase of Bacteroidota. In conclusion, our results revealed the great potential of CCHP to alleviate brain inflammation in colitis mice by inhibiting the NF-κB signaling pathway and regulating gut microbiota.

Orange Pectin with Compact Conformation Effectively Alleviates Acute Colitis in Mice

A comprehensive understanding of the relationships between the structure and function is critical for the targeted preparation of functional pectins. In this study, we compared the alleviating effects of five orange pectins (200 mg/kg) extracted using acid (P2), alkali (P10), cellulase (C), acid + cellulase (P2 + C), and alkali + cellulase (P10 + C) on dextran sodium sulfate-induced acute colitis. The physiological and histopathological indicators revealed that the alleviating effects were most significant for P10 + C, followed by P10, P2 + C, P2, and C. P10 + C increased the diversity and relative abundance of Akkermansia, leading to increased generation of colonic short-chain fatty acids as well as mRNA and protein expressions of GPR43, GPR109A, claudin-1, ZO-1, and occludin. Therefore, proinflammatory cytokines were decreased, and anti-inflammatory cytokines were increased. A compact conformation of P10 + C contributed to the alleviation effects on acute colitis. Alkali + cellulase-extracted orange pectin with a compact conformation has potential as adjuvant treatment for intestinal inflammation.

Natural flavone tricin exerted anti-inflammatory activity in macrophage via NF-κB pathway and ameliorated acute colitis in mice

BACKGROUND

Ulcerative colitis is a subtype of inflammatory bowel disease, characterized by relapsing inflammation in the gastrointestinal tract with limited treatment options. Previous studies suggested that the natural compound tricin, a flavone isolated from rice bran, could suppress chemically-induced colitis in mice, while our recent study also demonstrated the anti-metastatic effect of tricin in colon tumor-bearing mice.

HYPOTHESIS/PURPOSE

Here we further investigated the underlying mechanism of the inhibitory effects of tricin on lipopolysaccharides-activated macrophage RAW264.7 cells and explored the efficacy of tricin in acute colitis mouse model induced by 4.5% dextran sulfate sodium (DSS) for 7 days.

METHODS

Tricin (75, 100, and 150 mg/kg) or the positive control drug sulfasalazine (200 mg/kg) were orally administered to mice for 7 days. Stool consistency scores, stool blood scores, and body weight were recorded daily. Disease activity index (DAI) was examined on day 7, and colon tissues were collected for biochemical analyses. The fecal microbiome of colitis mice after tricin treatment was characterized for the first time in this study using 16S rDNA amplicon sequencing.

RESULTS

Results showed that tricin (50 µM) remarkably reduced nitric oxide production in lipopolysaccharides-activated RAW264.7 cells and the anti-inflammatory activity of tricin was shown to act through the NF-κB pathway. Besides, tricin treatment at 150 mg/kg significantly reversed colon length reduction, reduced myeloperoxidase activities and DAI scores, as well as restored the elevated myeloid-derived suppressive cells population in acute colitis mice. The influence from DSS on gut microbiota, such as the increased population of Proteobacteria phylum and Ruminococcaceae family, was shown to be relieved after tricin treatment.

CONCLUSION

Our present study firstly demonstrated that tricin ameliorated acute colitis by improving colonic inflammation and modulating gut microbiota profile, which supports the potential therapeutic use of tricin for colitis treatment.

Microbiota regulate innate immune signaling and protective immunity against cancer

Microbiota play critical roles in regulating colitis and colorectal cancer (CRC). However, it is unclear how the microbiota generate protective immunity against these disease states. Here, we find that loss of the innate and adaptive immune signaling molecule, TAK1, in myeloid cells (Tak1^ΔM/ΔM) yields complete resistance to chemical-induced colitis and CRC through microbiome alterations that drive protective immunity. Tak1^ΔM/ΔM mice exhibit altered microbiota that are critical for resistance, with antibiotic-mediated disruption ablating protection and Tak1^ΔM/ΔM microbiota transfer conferring protection against colitis or CRC. The altered microbiota of Tak1^ΔM/ΔM mice promote IL-1β and IL-6 signaling pathways, which are required for induction of protective intestinal Th17 cells and resistance. Specifically, Odoribacter splanchnicus is abundant in Tak1^ΔM/ΔM mice and sufficient to induce intestinal Th17 cell development and confer resistance against colitis and CRC in wild-type mice. These findings identify specific microbiota strains and immune mechanisms that protect against colitis and CRC.

The Mechanism of Lavender Essential Oil in the Treatment of Acute Colitis Based on "Quantity-Effect" Weight Coefficient Network Pharmacology

This study aimed to introduce a new weight coefficient combined with network pharmacology to predict the potential active components, action targets, and signal pathways of lavender essential oil and to investigate the therapeutic effect of lavender essential oil on colitis through animal experiments. The component targets of lavender essential oil were mined from the Pubchem and SwissTargetPrediction databases, and the relative content of lavender essential oil was compared with OB (oral bioavailability) to establish a “quantity–effect” weight coefficient. Online databases such as GeneCards and String were used to construct a “lavender essential oil compound target disease target” network to extract the key targets of core compounds acting on diseases. The clusterProfiler package in R language programming of Rstudio software was used to analyze the enrichment of the related targets by Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes (KEGG), and the enriched pathways were reordered according to the “quantity–effect” weight coefficient of the targets they participated in. Following up on the findings, the pharmacodynamic test showed that, after injecting lavender essential oil into mice, the levels of inflammatory cytokines including EGFR, TNF-α, and IFN-γ in serum and colon tissue decreased, and lavender essential oil could mediate Th17 cell differentiation by reducing dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) colonic mucosal damage. The results indicated that lavender essential oil can alleviate DSS-induced colonic mucosal injury in ulcerative Colitis mice. Based on the network pharmacology of the “quantity–effect” weight coefficient, this study indicated that lavender essential oil can regulate the level of inflammatory factors, inhibit inflammatory reactions through a multicomponent and multitarget strategy, and ultimately alleviate the colonic mucosal injury of UC mice. Through the weight coefficient network pharmacology mining, it was concluded that the Th17 cell differentiation, PI3K-Akt signaling pathway, and Th1 and Th2 cell differentiation of lavender essential oil in the treatment of UC may be the key pathway for the treatment of the disease. Through the establishment of a weight coefficient combined with network pharmacology and the combination of dose and effect, it shows that network pharmacology may provide a better basis for the treatment of disease mechanism.

CD137 Signaling Regulates Acute Colitis via RALDH2-Expressing CD11b-CD103+ DCs

CD137, a potent costimulatory receptor for CD8⁺ T cells, is expressed in various non-T cells, but little is known about its regulatory functions in these cells. In this study, we show that CD137 signaling, specifically in intestinal CD11b^-CD103⁺ dendritic cells (DCs), restricts acute colitis progression. Mechanistically, CD137 engagement activates TAK1 and subsequently stimulates the AMPK-PGC-1α axis to enhance expression of the Aldh1a2 gene encoding the retinoic acid (RA) metabolizing enzyme RALDH2. RA can act on CD11b⁺CD103^- DCs and induce SOCS3 expression, which, in turn, suppresses p38MAPK activation and interleukin-23 (IL-23) production. Administration of RA in DC-specific CD137^-/- mice represses IL-23-producing CD11b⁺CD103^- DCs and T_H17 cells, indicating that RA is a major inhibitory effector molecule against intestinal CD11b⁺CD103^- DCs. Additionally, the therapeutic effect of the anti-CD137 antibody is abrogated in DC-specific CD137^-/- mice. Taken together, our results define a mechanism of paracrine immunoregulation operating between adjacent DC subsets in the intestine.

Murine Intrarectal Instillation of Purified Recombinant Clostridioides difficile Toxins Enables Mechanistic Studies of Pathogenesis

Clostridioides difficile is linked to nearly 225,000 antibiotic-associated diarrheal infections and almost 13,000 deaths per year in the United States. Pathogenic strains of C. difficile produce toxin A (TcdA) and toxin B (TcdB), which can directly kill cells and induce an inflammatory response in the colonic mucosa. Hirota et al. (S. A. Hirota et al., Infect Immun 80:4474-4484, 2012) first introduced the intrarectal instillation model of intoxication using TcdA and TcdB purified from VPI 10463 (VPI 10463 reference strain [ATCC 43255]) and 630 C. difficile strains. Here, we expand this technique by instilling purified, recombinant TcdA and TcdB, which allows for the interrogation of how specifically mutated toxins affect tissue. Mouse colons were processed and stained with hematoxylin and eosin for blinded evaluation and scoring by a board-certified gastrointestinal pathologist. The amount of TcdA or TcdB needed to produce damage was lower than previously reported in vivo and ex vivo Furthermore, TcdB mutants lacking either endosomal pore formation or glucosyltransferase activity resemble sham negative controls. Immunofluorescent staining revealed how TcdB initially damages colonic tissue by altering the epithelial architecture closest to the lumen. Tissue sections were also immunostained for markers of acute inflammatory infiltration. These staining patterns were compared to slides from a human C. difficile infection (CDI). The intrarectal instillation mouse model with purified recombinant TcdA and/or TcdB provides the flexibility needed to better understand structure/function relationships across different stages of CDI pathogenesis.

Glochidion ellipticum Wight extracts ameliorate dextran sulfate sodium-induced colitis in mice by modulating nuclear factor kappa-light-chain-enhancer of activated B cells signalling pathway

OBJECTIVES

Glochidion ellipticum Wight is a medicinal plant, rich in polyphenols, frequently used by the indigenous communities of Bangladesh and possess with multiple health benefits. It exerts anti-inflammatory and antidiarrheal properties, but the detailed chemical constituents are yet to be elucidated.

METHODS

Glochidion ellipticum extracts were analyzed using ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry and then tested by both lipopolysaccharide (LPS) induced inflammation of Raw 264.7 macrophage cells and dextran sulfate sodium (DSS) induced acute colitis model. Blood serum was taken for fluorescein isothiocyanate-dextran (FITC-dextran) measurement and tissue samples were used to perform histology, RT-PCR and Western blotting.

KEY FINDINGS

The extracts could lower the levels of nitric oxide (NO), reactive oxygen species (ROS) and pro-inflammatory cytokines significantly in LPS induced macrophage cells. The extracts could also reduce disease activity index (DAI) score, restore antioxidants and pro-oxidants and improve macroscopic and microscopic features of colonic tissues in DSS induced mice. Expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in protein level was markedly diminished (up to 51.21% and 71.11%, respectively) in the treatment groups compared to the model group of colitic mice.

CONCLUSIONS

Our findings suggested that G. ellipticum extracts ameliorate DSS colitis via blocking nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway, which make them to be potential candidates for further research against inflammation and colitis.

Novel Histone Deacetylase 6 Inhibitor CKD-506 Inhibits NF-κB Signaling in Intestinal Epithelial Cells and Macrophages and Ameliorates Acute and Chronic Murine Colitis

BACKGROUND

Selective blocking of HDAC6 has become a promising strategy in treating inflammatory bowel disease. CKD-506 is a novel isoform-selective inhibitor of histone deacetylase 6. The present study was performed to evaluate the effect of CKD-506 on the NF-κB signaling pathway in intestinal epithelial cells (IECs) and macrophages and on murine models of acute and chronic colitis.

METHODS

RAW264RAW264.7 murine macrophages and COLO 205 human IECs were pretreated with CKD-506 and then stimulated with lipopolysaccharides (LPS). Cytokine expression of TNF-α, interleukin (IL)-6, IL-8, and IL-10 was measured by ELISA. The effect of CKD-506 on NF-κB signaling was evaluated by Western blotting of IκBα phosphorylation/degradation and electrophoretic mobility shift assay. In vivo studies were performed using a dextran sulfate sodium (DSS)-induced acute colitis model, a chronic colitis model in IL-10 knockout mice, and an adoptive transfer model. Colitis was quantified by the disease activity index, colon length, and histopathologic evaluation.

RESULTS

CKD-506 suppressed the expression of pro-inflammatory cytokines such as IL-6, IL-8, and TNF-α in IECs and macrophages. CKD-506 strongly inhibited IκBα phosphorylation/degradation and the DNA-binding activity of NF-κB. Oral administration of CKD-506 attenuated DSS-induced acute colitis and chronic colitis in IL-10-/- and adoptive transfer models. CKD-506 ameliorated weight loss, disease activity, and histopathologic score in colitis mice and downregulated IκBα phosphorylation and pro-inflammatory cytokine production significantly.

CONCLUSIONS

CKD-506 blocked NF-κB signaling in IECs and macrophages and ameliorated experimental acute and chronic murine colitis models, which suggests that CKD-506 is a promising candidate for inflammatory bowel disease treatment as a small molecular medicine.

Regulation of S100A8 Stability by RNF5 in Intestinal Epithelial Cells Determines Intestinal Inflammation and Severity of Colitis

Inflammatory bowel disease (IBD) is prevalent, but the mechanisms underlying disease development remain elusive. We identify a role for the E3 ubiquitin ligase RNF5 in IBD. Intestinal epithelial cells (IECs) express a high level of RNF5, while the colon of Rnf5^−/− mice exhibits activated dendritic cells and intrinsic inflammation. Rnf5^−/− mice exhibit severe acute colitis following dextran sodium sulfate (DSS) treatment. S100A8 is identified as an RNF5 substrate, resulting in S100A8 ubiquitination and proteasomal-dependent degradation that is attenuated upon inflammatory stimuli. Loss of RNF5 from IECs leads to enhanced S100A8 secretion, which induces mucosal CD4⁺ T cells, resulting in Th1 pro-inflammatory responses. Administration of S100A8-neutralizing antibodies to DSS-treated Rnf5^−/− mice attenuates acute colitis development and increases survival. An inverse correlation between RNF5 and S100A8 protein expression in IECs of IBD patients coincides with disease severity. Collectively, RNF5-mediated regulation of S100A8 stability in IECs is required for the maintenance of intestinal homeostasis.

Fujita et al. show that RNF5 regulation of S100A8 stability in intestinal epithelial cells defines the degree of pro-inflammatory response, culminating in severe intestinal inflammation following DSS treatment to Rnf5^−/− mice. Neutralizing S100A8 antibodies attenuates acute colitis phenotypes, and inverse RNF5/S100A8 expression coincides with clinical severity in IBD patients.

Systematic understanding of the mechanism and effects of Arctigenin attenuates inflammation in dextran sulfate sodium-induced acute colitis through suppression of NLRP3 inflammasome by SIRT1

Arctigenin (ARC-G) is the main active ingredient extracted from Great Burdock Achene, with extensive pharmacological effects. In addition, ARC-G has been suggested to show excellent efficacy on inflammatory disease. This study aimed to defined that the function of Arctigenin attenuates inflammation in dextran sulfate sodium (DSS)-induced acute colitis, to determine its possible mechanism. Mice was induced by giving 2.0% DSS in the drinking water for DSS-induced acute colitis. Mice of acute colitis were injected intraperitoneally with 20 mg/kg per day of Arctigenin for 7 days. MPO activity levels were measured using MPO activity kits. Western Blot Analysis was used to determine the protein expression. Arctigenin prevents colitis and attenuates inflammation in DSS-induced acute colitis. Arctigenin suppressed NLRP3 inflammasome by SIRT1 in DSS-induced acute colitis. In THP-1 cell by LPS model, Arctigenin suppressed NLRP3, caspase-1 and IL-1β protein expression by SIRT1. Si-NLRP3 increases the effects of Arctigenin on inflammation in THP-1 cell by LPS model. Si-SIRT1 decreases the effects of Arctigenin on inflammation in THP-1 cell by LPS model. INF39, NLRP3 inhibitor also increased the effects of Arctigenin on inflammation in DSS-induced acute colitis. SIRT1 inhibitor also decreases the effects of Arctigenin on inflammation in DSS-induced acute colitis. Taken together our results demonstrated that Arctigenin attenuates inflammation in DSS-induced acute colitis through suppression of NLRP3 inflammasome by SIRT1.

Synergistic effect of combined melatonin and adipose-derived mesenchymal stem cell (ADMSC)-derived exosomes on amelioration of dextran sulfate sodium (DSS)-induced acute colitis

This study tested the hypothesis that melatonin (Mel) and adipose-derived mesenchymal stem cell-derived exosomes effectively suppress dextran sulfate sodium (DSS)-induced acute inflammatory colitis (AIC) in rats. To determine whether Mel-exosome treatment could ameliorate the severity of AIC, we treated Sprague Dawley rats with DSS-induced AIC with Mel, exosomes, or combined Mel-exosome therapy and evaluated the effects on AIC. First, to induce an inflammatory response in vitro, we treated HT-29 cells with lipopolysaccharide (LPS) and evaluated the response to Mel and/or exosome treatment. We found that expression of NOX-1, NOX-2, MMP-9, NF-κB, iNOS, ICAM-1, and COX-2 was significantly higher in HT-29 cells treated with LPS than in control cells, and was significantly reduced by either exosome or Mel treatment (P<0.001 for all). In vivo, flow cytometric analysis showed that, compared to untreated rats with AIC, the number of circulating inflammatory cells was lowest in rats treated with combined Mel-exosome treatment than in rats treated with either Mel or exosomes alone (P<0.0001). Compared with controls, as well as Mel or exosome treatment alone, combined Mel-exosome treatment ameliorated the effects of DSS-induced AIC as evidenced by changes in the expression of markers for inflammation, oxidative stress, apoptosis, and fibrosis (P<0.0001 for all). Additionally, histopathological findings showed that colon injury score, expression of inflammatory and DNA-damage markers, and bloody stool were all improved following combined Mel-exosome treatment (P<0.0001 for all). In conclusion, combined Mel-exosome treatment significantly protected the rat colon against DSS-induced AIC injury.

Targeted deletion of miR-139-5p activates MAPK, NF-κB and STAT3 signaling and promotes intestinal inflammation and colorectal cancer

miR-139-5p, which has been reported to be underexpressed in several types of cancer, is associated with tumorigenesis by participating in various biological processes via the modulation of different target genes. In the present study, we analyzed mice deficient in miR-139-5p, aiming to investigate its role in intestinal inflammation and colitis-associated colorectal cancer. We show that miR-139-5p knockout (KO) mice are highly susceptible to colitis and colon cancer, accompanied by elevated proliferation and decreased apoptosis, as well as an increased production of inflammatory cytokines, chemokines and tumorigenic factors. Furthermore, enhanced colon inflammation and colorectal tumor development in miR-139-5p KO mice are a result of the regulatory effects of miR-139-5p on its target genes for Rap1b and nuclear factor-kappa B, thus affecting the activity of the mitogen-activated protein kinase, nuclear factor-kappa B and signal transducer and activator of transcription 3 signaling pathways. These results reveal a critical part for miR-139-5p in maintaining intestinal homeostasis and protecting against colitis and colorectal cancer in vivo, providing new insights into the function of miR-139-5p with respect to linking inflammation to carcinogenesis.

VEGFR-3 blocking deteriorates inflammation with impaired lymphatic function and different changes in lymphatic vessels in acute and chronic colitis

BACKGROUND

Recent studies show inflammation-associated lymphangiogenesis (IAL) induced by vascular endothelial growth factor receptor 3 (VEGFR-3) pathway has a close relationship with chronic intestinal inflammation, and antilymphatic signaling pathways may repress IAL. However, whether the biologic function of lymphatic vessel is the same in severe acute intestinal inflammation still remain unknown.

METHODS

C57BL/6 mice were administered with 5% of dextran sodium sulfate (DSS) in drinking water for 7 days to establish severe acute colitis (SAC) model. Chronic colitis (CC) model was established by three cycles of 2% DSS for 5 days following water for 5 days. Mice were treated with VEGFR-3 antibody once daily in SAC group, or once every 3 days in CC group. The colon inflammation, submucosal edema, lymphatic vessel (LV) density, LV size, lymph flow, cytokines and immune cells infiltration were detected.

RESULTS

Both acute and chronic colitis resulted in a significant aggravation of colon inflammation in anti-VEGFR-3-treated mice, compared with PBS-treated colitis mice. Meanwhile, this was accompanied with decreased lymph drainage, increased submucosal edema, inflammatory cells infiltration and cytokines levels. In acute intestinal inflammation, significantly distorted and enlarged lymphatics were found but the LV number remained unchanged; not only significantly distorted and enlarged lymphatics but reduced LV number were found in chronic colitis.

CONCLUSION

Blocking VEGFR-3 in acute and chronic colitis leads to deterioration of colon inflammation with impaired lymphatic function and different changes in LVs. In the therapy targeting VEGF-C/VEGFR-3 pathway for lymphangiogenesis, the phrase and severity of intestinal inflammation should be taken into account.

Management of acute colitis and toxic megacolon

Severe colitis is a well-defined condition that can develop in patients afflicted with ulcerative colitis, but typically responds to a variety of medical therapies. Operative intervention is warranted when massive hemorrhage, perforation, or peritonitis complicates the clinical scenario or medical therapy fails to control the disease. Of the operative options, total/subtotal colectomy and end ileostomy is the usual procedure of choice especially if the operation can be performed through a laparoscopic approach.