Amelioration Of Intestinal Inflammation Research Articles

Indole-3-Carbinol-Dependent Aryl Hydrocarbon Receptor Signaling Attenuates the Inflammatory Response in Experimental Necrotizing Enterocolitis.

Necrotizing enterocolitis (NEC) causes significant morbidity and mortality in premature infants; therefore, the identification of therapeutic and preventative strategies against NEC remains a high priority. The ligand-dependent transcription factor aryl hydrocarbon receptor (AhR) is well known to contribute to the regulation of intestinal microbial communities and amelioration of intestinal inflammation. However, the role of AhR signaling in NEC is unclear. Experimental NEC was induced in 4-d-old wild-type mice or mice lacking AhR expression in the intestinal epithelial cells or AhR expression in CD11c+ cells (AhRΔCD11c) by subjecting animals to twice daily hypoxic stress and gavage feeding with formula supplemented with LPS and enteric bacteria. During NEC, compared with wild-type mice treated with vehicle, littermates treated with an AhR proligand, indole-3-carbinol, had reduced expression of Il1b and Marco, a scavenger receptor that mediates dendritic cell activation and the recognition and clearance of bacterial pathogens by macrophages. Furthermore, indole-3-carbinol treatment led to the downregulation of genes involved in cytokine and chemokine, as revealed by pathway enrichment analysis. AhR expression in the intestinal epithelial cells and their cre-negative mouse littermates were similarly susceptible to experimental NEC, whereas AhRΔCD11c mice with NEC exhibited heightened inflammatory responses compared with their cre-negative mouse littermates. In seeking to determine the mechanisms involved in this increased inflammatory response, we identified the Tim-4− monocyte-dependent subset of macrophages as increased in AhRΔCD11c mice compared with their cre-negative littermates. Taken together, these findings demonstrate the potential for AhR ligands as a novel immunotherapeutic approach to the management of this devastating disease.

Effect of Synbiotics on Amelioration of Intestinal Inflammation Under Hypobaric Hypoxia.

Khanna, Kunjan, Kamla Prasad Mishra, Sudipta Chanda, Lilly Ganju, Shashi Bala Singh, and Bhuvnesh Kumar. Effect of synbiotics on amelioration of intestinal inflammation under hypobaric hypoxia. High Alt Med Biol. 22:32-44, 2021. Aim: High-altitude exposure alters the gastrointestinal (GI) system, which may be a cause of hypobaric hypoxia (HH)-induced microbial dysbiosis. Therefore, we investigated the effect of a combination of beneficial bacteria and nondigestible fiber popularly known as "synbiotics" (Syn) to mitigate intestinal inflammation and microbial dysbiosis post-HH exposure. Methods: Syn, that is, a combination of probiotics and prebiotics, was given to male Sprague-Dawley rats 3 days prior and along with the HH exposure to assess its effect on mucosal barrier injury and inflammation. Changes in the gut microbiota and functional analysis were assessed using 16S rRNA and whole-genome sequencing (WGS) analysis. Results: Syn treatment significantly improved mucosal barrier injury in terms of decreased serum fluorescein isothiocyanate dextran from 96.1 ± 7.95 μg/ml in HH-alone group to 38.35 ± 4.55 μg/ml in HH + Syn group (p < 0.01) and decreased serum zonulin levels, that is, from 134.7 ± 19.05 ng/ml (HH alone) to 64.02 ± 7.33 ng/ml (HH + Syn) (p < 0.05), along with improvement in the intestinal villi under HH exposure. Levels of proinflammatory cytokines and chemokines significantly reduced upon Syn treatment, indicating attenuation of inflammation and immune cell migration. Syn treatment significantly reduced Th17 biased immune response preventing interleukin (IL)-17-induced inflammatory response with 8.1 ± 0.5 ng/mg protein in HH exposure group, while treatment with Syn in HH-exposed group reduced IL-17 levels to 2.01 ± 0.3 ng/mg protein (p < 0.001). Analysis of 16S rRNA showed significant (p < 0.05) alterations in Deferribacteres, Firmicutes, and Verrucomicrobia at the phylum levels, whereas Prevotella, Paenibacillus, Clostridium, Turicibacter, Bacillus, Anoxybacillus, Enterococcus, SMB53, Mucispirillum, Allobaculum, and Lactococcus were significantly altered (p < 0.05) in abundance at the genus level. WGS analysis revealed improvement in GI health by regulating functional pathways post-Syn treatment. Conclusion: Our findings indicate that Syn treatment improves intestinal barrier function and curtailed inflammation in the HH-exposed rat models, proving it to be a promising potential countermeasure for HH-induced gut problems.

RETRACTED: miRNA-129/FBW7/NF-κB, a Novel Regulatory Pathway in Inflammatory Bowel Disease

F-box and WD repeat domain-containing protein 7 (FBW7) has been documented to be implicated in nuclear factor κB (NF-κB) signaling and inflammation, but its role in the pathogenesis of inflammatory bowel disease (IBD) remains unknown. FBW7 was increased both in colon tissues from IBD patients and trinitrobenzene sulphonic acid (TNBS)-induced colitis mice. Immunoprecipitation assay identified that FBW7 as a novel inhibitor of κBα (IκBα)-binding partner. FBW7 upregulation promoted IκBα ubiquitin-dependent degradation, NF-κB activation, and subsequent intestinal inflammation in intestinal epithelial cells, whereas inhibition of FBW7 produced the opposite effects. Computational analysis revealed that microRNA-129 (miR-129) directly targets at 3′ UTR of FBW7. The miR-129-suppressed proteasome pathway mediated the degradation of IκBα by negatively regulating FBW7. The in vivo study demonstrated that upregulation of miR-129 ameliorated intestinal inflammation in TNBS-induced colitis mice through inhibition of the NF-κB signaling pathway. In conclusion, FBW7 is a novel E3 ubiquitin ligase for IκBα and thereby leads to NF-κB activation and inflammation. miR-129 negatively regulates FBW7 expression, resulting in secondary inhibition of the NF-κB pathway and amelioration of intestinal inflammation. Our findings provide new insight into the development of therapeutic strategies for the treatment of IBD.

Intestinal Anti-Inflammatory Activity of Perillaldehyde.

Monoterpenoid perillaldehyde (PA) is the major component in Perilla frutescens leaf essential oil, but its function regarding anti-inflammatory effect is unclear. We explored the anti-inflammatory activity of PA in a dextran sulfate sodium (DSS)-induced colitis mouse model using relief of bodyweight loss (avg. 49.2% mitigation; P = 0.094) and colon damage (avg. 35.3% mitigation; P < 0.05) by administration of PA at a 100 mg/kg dosage. The PA administration resulted in suppression of DSS-induced expression of pro-inflammatory cytokine genes and matrix metalloproteinase-9 in the colon (e.g., avg. 60.6% mitigation for TNF-α mRNA levels; P < 0.05). These effects were confirmed in macrophage RAW264.7 cells stimulated with lipopolysaccharide (LPS). Application of PA induced cell suppression of LPS-induced expressions of genes and proteins of pro-inflammatory cytokines and induced activation of c-Jun N-terminal kinases (JNKs, p54 and p46; P < 0.05) but not nuclear factor-κB p65. The half maximal inhibitory concentration for decreased expression levels of TNF-α mRNA was 171.7 μM. We discuss the in vivo function of PA in amelioration of intestinal inflammation via JNK-mediated cytokine regulation.

P004 Stimulation of CYP450-mediated ω-3 docosahexaenoic acid metabolism via MFSD2A as a novel therapy for inflammatory bowel disease

Background: New evidences indicate that defects in pro-resolving pathways might underlie the pathogenesis of IBD. The resolution process is regulated by lipid mediators, such as those derived from the ω-3 docosahexaenoic acid (DHA), whose esterified form is transported by the Major Facilitator Superfamily Domain containing 2A (MFSD2A) through the endothelium of brain, retina, and placenta. We investigated if and how MFSD2A may modulate the lipid metabolism of gut endothelial cells, thus promoting the resolution of intestinal inflammation. Methods: Lipidomic analysis was performed by Liquid chromatography–mass spectrometry on both mucosal biopsies and primary human intestinal microvascular endothelial cells (HIMEC) isolated from surgical specimens of active, drug-induced resolving patients and healthy non-IBD subjects. Using a lentiviral strategy, healthy HIMEC were transduced with a lentivirus carrying GFP-tagged MFSD2A overexpressing vector (MFSD2A-OE), and assayed for their angiogenic properties and response to an inflammatory stimuli. Adoptive transfer of human circulating endothelial progenitor cells (ECFCs), genetically engineered to overexpress MFSD2A, was performed in CD1 nude colitic mice, along with orally administered DHA. Results: The lipidomic analysis revealed a reduced percentage of pro-resolving metabolites derived from Cytochrome P450 epoxygenation of DHA in the inflamed mucosa, when compared with samples from healthy and resolving tissues (1.40±0.09% vs 0.85±0.15% over total fatty acids; p<0.05). Interestingly, we found that reduced level of epoxy-DHA derivatives in active tissues correlated with lower amounts of MFSD2A compared to resolving mucosa (2±0.3 vs 1±0.1; p<0.01). MFSD2A, found exclusively expressed by gut endothelium, exerted pro-resolving effects in HIMEC in terms of reduced pro-inflammatory markers and anti-angiogenic functions. Transplantation of engineered human MFSD2A-OE ECFCs in DHA–fed colitic mice, resulted in amelioration of intestinal inflammation, through stimulation of docosanoids production in the inflamed mucosa. These pro-resolving effects of MFSD2A were completely abolished by CYP2C inhibitor both in vitro and in vivo, demonstrating that protective functions exerted by MFSD2A depends on epoxy metabolites of DHA. Conclusions: Our study provides not only important insights into the molecular mechanisms regulating resolution of intestinal inflammation, but also a strong rationale for the development of novel therapeutic strategies to treat IBD. Our cell-based therapeutic approach may help a selective cohort of non-responding patients, with the potential advantage of avoiding immune suppression, and using natural endogenous pathways to resolve inflammation.

MicroRNA‐146b improves intestinal injury in mouse colitis by activating nuclear factor‐κB and improving epithelial barrier function

The precise role of microRNAs in inflammatory disease is not clear. The present study investigated the effect of microRNA (miR-146b) with respect to improving intestinal inflammation. The microRNA profile in interleukin-10 deficient mice was examined using microRNA arrays and miR-146b was selected for the subsequent experiments. The expression vectors containing either the whole sequence of miR-146b or small interfering RNA for miR-146b were intraperitoneally administered to the dextran sodium sulfate (DSS)-induced colitis mouse. The expression levels of inflammation-related mediators were examined by the reverse transcriptase-polymerase chain reaction and western blotting analysis. Intestinal barrier function was evaluated by an ex vivo mannitol flux study. The overexpression of miR-146b activated the NF-κB pathway, improved epithelial barrier function, relieved intestinal inflammation in the DSS-induced colitis mice, and improved the survival rate of mice with lethal colitis. Furthermore, this amelioration of intestinal inflammation by miR-146b was negated by the inhibitor for the NF-κB pathway. The overexpression of miR-146b decreased the expression of siah2, which has a target sequence for miR-146b, and promoted the ubiquitination of TRAF proteins. This suggests that the up-regulation of NF-κB by miR-146b was mediated by inhibition of the ubiquitination of TRAF proteins upstream of NF-κB. miR-146b improves intestinal inflammation by up-regulating NF-κB as a result of the decreased expression of siah2, which ubiquitinates TRAF proteins. Modulation of the miR-146b expression is a potentially useful therapy for the treatment of intestinal inflammation via activation of the NF-κB pathway.

Cellulose Supplementation Early in Life Ameliorates Colitis in Adult Mice

Decreased consumption of dietary fibers, such as cellulose, has been proposed to promote the emergence of inflammatory bowel diseases (IBD: Crohn disease [CD] and ulcerative colitis [UC]) where intestinal microbes are recognized to play an etiologic role. However, it is not known if transient fiber consumption during critical developmental periods may prevent consecutive intestinal inflammation. The incidence of IBD peaks in young adulthood indicating that pediatric environmental exposures may be important in the etiology of this disease group. We studied the effects of transient dietary cellulose supplementation on dextran sulfate sodium (DSS) colitis susceptibility during the pediatric period in mice. Cellulose supplementation stimulated substantial shifts in the colonic mucosal microbiome. Several bacterial taxa decreased in relative abundance (e.g., Coriobacteriaceae [p = 0.001]), and other taxa increased in abundance (e.g., Peptostreptococcaceae [p = 0.008] and Clostridiaceae [p = 0.048]). Some of these shifts persisted for 10 days following the cessation of cellulose supplementation. The changes in the gut microbiome were associated with transient trophic and anticolitic effects 10 days following the cessation of a cellulose-enriched diet, but these changes diminished by 40 days following reversal to a low cellulose diet. These findings emphasize the transient protective effect of dietary cellulose in the mammalian large bowel and highlight the potential role of dietary fibers in amelioration of intestinal inflammation.