CD34 is required for infiltration of eosinophils into the colon and pathology associated with DSS-induced ulcerative colitis.

Eosinophil migration into the gut and the release of granular mediators plays a critical role in the pathogenesis of inflammatory bowel diseases, including ulcerative colitis. We recently demonstrated that eosinophil migration into the lung requires cell surface expression of the sialomucin CD34 on mast cells and eosinophils in an asthma model. Based on these findings, we investigated a similar role for CD34 in the migration of eosinophils and other inflammatory cells into the colon as well as explored the effects of CD34 ablation on disease development in a dextran sulfate sodium-induced model of ulcerative colitis. Our findings demonstrate decreased disease severity in dextran sulfate sodium-treated Cd34(-/-) mice, as assessed by weight loss, diarrhea, bleeding, colon shortening and tissue pathology, compared with wild-type controls. CD34 was predominantly expressed on eosinophils within inflamed colon tissues, and Cd34(-/-) animals exhibited drastically reduced colon eosinophil infiltration. Using chimeric animals, we demonstrated that decreased disease pathology resulted from loss of CD34 from bone marrow-derived cells and that eosinophilia in Cd34(-/-)IL5(Tg) animals was sufficient to overcome protection from disease. In addition, we demonstrated a decrease in peripheral blood eosinophil numbers following dextran sulfate sodium treatment. These findings demonstrate that CD34 was expressed on colon-infiltrating eosinophils and played a role in eosinophil migration. Further, our findings suggest CD34 is required for efficient eosinophil migration, but not proliferation or expansion, in the development of ulcerative colitis.

Comparative expression profiling in the intestine of patients with Giardia-induced postinfectious functional gastrointestinal disorders.

BACKGROUND: A Giardia outbreak in Bergen, Norway, caused postinfectious functional gastrointestinal disorders (PI-FGIDs). Despite the devastating effects of this outbreak, it presented a unique chance to investigate the implication on the dysregulation of genetic pathways in PI-FGID. METHODS: We performed the first comparative expression profiling of miRNAs and their potential target genes in microdissected rectal biopsies from 20 Giardia-induced PI-FGID patients vs 18 healthy controls by nCounter analysis. Subsequently, candidates were validated on protein level by immunostaining. KEY RESULTS: miRNA profiling on rectal biopsy samples from 5 diarrhea-predominant PI-IBS cases compared to 10 healthy controls revealed differential expression in the epithelial layer. The top five regulated miRNAs were implicated in GI disease, inflammatory response, and immunological disease. Subsequently, these miRNAs and 100 potential mRNA targets were examined in 20 PI-FGID cases and 18 healthy controls in both the mucosal epithelium and the lamina propria. Although deregulation of the selected miRNAs could not be verified in the larger sample set, mRNAs involved in barrier function were downregulated in the epithelium. Pro-inflammatory genes and genes implicated in epigenetic modifications were upregulated in the lamina propria. Immunostaining for selected candidates on 17 PI-FGID cases and 16 healthy controls revealed increased tryptase levels as well as a decreased and aberrant subcellular expression of occludin. CONCLUSIONS AND INFERENCES: Genes relevant to immune and barrier function as well as stress response and epigenetic modulation are differentially expressed in PI-FGIDs and may contribute to disease manifestation.

Natural products as promising drug candidates for the treatment of hepatitis B and C.

Hepatitis B virus (HBV) or hepatitis C virus (HCV) infections are a major threat worldwide. Combination therapy of interferon-alpha and ribavirin is currently the treatment of choice for HCV-infected patients. However, this regimen is only effective in approximately 50% of patients and provokes severe side-effects. Numerous natural alternatives for treating HCV have been suggested. Deoxynojirimycin and its derivatives are iminosugars which exert anti-HCV activity by inhibiting alpha-glucosidases. A non-immunosuppressive derivate of cyclosporine A, NIM811, exerts anti-HCV activity by binding to cyclophilin. Other natural products with promising anti-HCV activity are 2-arylbenzofuran derivatives, Mellein, and pseudoguaianolides. For HBV treatment, several drugs are available, specifically targeting the virus polymerase (lamivudine, entecavir, telbivudine, and adefovir dipivoxil). The efficacy of these drugs is hampered by the development of resistance due to point mutations in the HBV polymerase. Due to drug resistance and adverse side-effects, the search for novel drugs is mandatory. Wogonin, ellagic acid, artemisinin and artesunate, chrysophanol 8-O-beta-D-glucoside, saikosaponin C, and protostane triterpenes are active against HBV. Natural products need to be investigated in more detail to explore their potential as novel adjuncts to established HBV or HCV therapy.

miR-16 and miR-103 impact 5-HT4 receptor signalling and correlate with symptom profile in irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a gut-brain disorder involving alterations in intestinal sensitivity and motility. Serotonin 5-HT4 receptors are promising candidates in IBS pathophysiology since they regulate gut motor function and stool consistency, and targeted 5-HT4R selective drug intervention has been proven beneficial in subgroups of patients. We identified a single nucleotide polymorphism (SNP) (rs201253747) c.*61 T > C within the 5-HT4 receptor gene HTR4 to be predominantly present in diarrhoea-IBS patients (IBS-D). It affects a binding site for the miR-16 family and miR-103/miR-107 within the isoforms HTR4b/i and putatively impairs HTR4 expression. Subsequent miRNA-profiling revealed downregulation of miR-16 and miR-103 in the jejunum of IBS-D patients correlating with symptoms. In vitro assays confirmed expression regulation via three 3'UTR binding sites. The novel isoform HTR4b_2 lacking two of the three miRNA binding sites escapes miR-16/103/107 regulation in SNP carriers. We provide the first evidence that HTR4 expression is fine-tuned by miRNAs, and that this regulation is impaired either by the SNP c.*61 T > C or by diminished levels of miR-16 and miR-103 suggesting that HTR4 might be involved in the development of IBS-D.