J. Jasper Deuring

Disease-related expression of the IL6/STAT3/SOCS3 signalling pathway in ulcerative colitis and ulcerative colitis-related carcinogenesis

Background Mouse models have shown that interleukin (IL)6 stimulates survival, proliferation and progression to cancer of intestinal epithelial cells via activation of signal transducers and activators of transcription 3 (STAT3). Objective To investigate the expression of IL6/phosphorylated STAT3 (p-STAT3)/suppressor of cytokine signalling 3 (SOCS3) in biopsy specimens from patients with ulcerative colitis (UC) and UC-related colorectal cancer (CRC) progression. Methods Biopsy specimens from patients with inactive UC (n=18), active UC (n=28), UC with low-grade dysplasia (LGD) (n=9), UC with high-grade dysplasia (HGD) (n=7), UC-CRC (n=11) and sporadic CRC (n=14) were included. Biopsy specimens (n=9) from patients without colonic abnormalities served as control. The protein expression of IL6, p-STAT3 and SOCS3 was determined immunohistochemically. Results Patients with active UC had significantly more IL6 and p-STAT3-positive epithelial cells than both patients with inactive UC and controls (strong positive IL6: 53.6%, 11.1% and 0%, respectively; p-STAT3: 64.3%, 22.2% and 11.1%, respectively; all p≤0.012). SOCS3-positive cells were significantly increased in colonic epithelium of both inactive and active UC compared with controls (strong positive: 94.4%, 96.4% and 11.1%, respectively; both p<0.001). In dysplasia and cancer, significantly more epithelial cells expressed IL6 and p-STAT3 compared with controls (strong positive IL6: 72.7% and 0% respectively; p-STAT3: 54.5% and 11.1%, respectively; both p<0.05), whereas the proportion of SOCS3-positive cells in this progression reduced (LGD 33.3%; HGD 14.3%; UC-CRC 9.1%). In addition, methylation of the SOCS3 gene was detected in epithelial cells from UC-CRC biopsy specimens. Conclusion The importance of IL6/p-STAT3 in patients with inflammation-induced CRC was demonstrated. Moreover, SOCS3 may be involved in UC pathogenesis and the absence of SOCS3 seems critical for CRC progression.

Genomic ATG16L1 risk allele-restricted Paneth cell ER stress in quiescent Crohn's disease

Objective Although genome wide association studies have partly uncovered the genetic basis of Crohns disease (CD), it remains a challenge to link genetic polymorphisms to functional intestinal phenotypes. Paneth cells are specialised antimicrobial epithelial cells localised to the small-intestinal crypt-base. Here, we investigate whether genomic variations in ATG16L1 affect Paneth cell function. Design Genomic variation of ATG16L1 (T300A, rs2241880) was determined in DNA from 78 patients with CD and 12 healthy controls. Paraffin-embedded ileal biopsies from patients with genotype AA (n=17), GA (n=38) and patients with the GG allele (n=23) were stained for GRP78, phospho-EIF2α, lysozyme, cleaved-caspase 3, phosphohistone H3, phospho-IκB, p65, phospho-p38MAPK and PHLDA1. Microbial composition of biopsies was assessed by PCR. Disease phenotype was scored. Results In patients with quiescent disease but with an ATG16L1 risk allele, the endoplasmic reticulum (ER) stress markers GRP78 and pEIF2α were highly expressed in Paneth cells. Other CD risk gene variations did not correlate with Paneth cell ER stress. Functionally, patients with ER-stressed Paneth cells showed no changes in intestinal epithelial cells proliferation or apoptosis, Paneth cell or stem cell numbers, p65, phospho-IκB and phospho-p38 staining. However, a significantly increased presence of adherent-invasive Escherichia coli was observed in biopsies from patients with ER-stressed Paneth cells. Phenotypically, patients with GRP78 positive Paneth cells have relatively less colonic disease over ileal disease (−21%, p=0.04), more fistulas (+21%, p=0.05) and an increased need for intestinal surgery (+38%, p=0.002). Conclusions The ATG16L1 T300A polymorphism defines a specific subtype of patients with CD, characterised by Paneth cell ER stress even during quiescent disease. Paneth cell ER stress correlates with bacterial persistence, and is thus likely to modulate antimicrobial functionality of this cell type in patients with CD.

Linking risk conferring mutations in NCF4 to functional consequences in Crohn's disease

We read with interest the paper from Muise et al in which they describe a rare variant in the NCF2 gene, which demonstrates a diminished RAC2 binding capacity.1 The NCF2 encoded protein p67phox is one of the components of the NADPH oxidase complex which drives the production of reactive oxygen species (ROS) during the bactericidal response of innate immune cells. Output of disturbed granulocytic ROS as a result of impaired functioning of this enzyme complex has been shown in a number of diseases, including myelodysplasia (MDS) and chronic granulomatous disease.2 3 As Muise and colleagues point out, these diseases have been linked to development of a colitis resembling that seen in Crohns disease (CD), suggesting a potential role for impaired ROS production in CD pathology. Genome-wide association studies (GWAS) are a promising tool to identify genetic variants …

Suppression of p21Rac Signaling and Increased Innate Immunity Mediate Remission in Crohn’s Disease

Overactivation of p21Rac1 is a rate-limiting step for innate immune function in Crohn’s disease and prevents remission. Crohn’s Disease on the Rac Crohn’s disease is a type of inflammatory bowel disease (IBD), wherein the body’s immune system attacks the gastrointestinal tract. In patients with Crohn’s, there are areas of apparently healthy tissue right next to damaged intestine, but it remains unclear what differentiates healthy and inflamed regions. Now, Parikh et al. examine signal transduction differences in healthy and inflamed tissue to find targets that may be protective in Crohn’s. The authors performed a comparative kinome profile in healthy controls as well as healthy and inflamed tissues from Crohn’s patients. They found that p21Rac1 GTPase signaling is suppressed in noninflamed tissue. What’s more, blocking p21Rac1 correlated with clinical improvement of IBD, potentially by boosting innate immune responses. These data suggest that blocking p21Rac1 may be protective for IBD. In inflammatory bowel disease (IBD), large areas of apparently healthy mucosa lie adjacent to ulcerated intestine. Knowledge of the mechanisms that maintain remission in an otherwise inflamed intestine could provide important clues to the pathogenesis of this disease and provide rationale for clinical treatment strategies. We used kinome profiling to generate comprehensive descriptions of signal transduction pathways in inflamed and noninflamed colonic mucosa in a cohort of IBD patients, and compared the results to non-IBD controls. We observed that p21Rac1 guanosine triphosphatase (GTPase) signaling was strongly suppressed in noninflamed colonic mucosa in IBD. This suppression was due to both reduced guanine nucleotide exchange factor activity and increased intrinsic GTPase activity. Pharmacological p21Rac1 inhibition correlated with clinical improvement in IBD, and mechanistically unrelated pharmacological p21Rac1 inhibitors increased innate immune functions such as phagocytosis, bacterial killing, and interleukin-8 production in healthy controls and patients. Thus, suppression of p21Rac activity assists innate immunity in bactericidal activity and may induce remission in IBD.

The cell biology of the intestinal epithelium and its relation to inflammatory bowel disease.

The epithelial layer of our intestines must meet two opposing requirements. On one hand it must allow for efficient uptake of nutrients and fluids, on the other hand it is a vital defence barrier between the milieu interior and the milieu exterior. In contrast to the lung that by virtue of cilia movement is kept virtually sterile, the gut epithelium is confronted by a stupendous microbiological load and a substantial xenobiotic challenge. The efficiency by which our intestinal epithelium manages to deal with the challenge of efficient nutrient absorption while simultaneously fulfilling its barrier function is testimony to what the forces of evolution can accomplish. Importantly, our understanding as to how our gut epithelial compartment manages this balancing act is now rapidly emerging, answering one of the oldest questions in cell biology. Importantly, when aberrations in this balance occur, for instance as a consequence genetic polymorphisms, increased propensity to develop chronic inflammation and inflammatory bowel disease is the result. Thus the knowledge on intestinal cell biology and biochemistry is not only of academic interest but may also aid design of novel avenues for the rational treatment of mucosal disease.

Impeded protein folding and function in active inflammatory bowel disease.

The intestinal tract is covered by a total of 300 square metres of IECs (intestinal epithelial cells) that covers the entire intestinal mucosa. For protection against luminal xenobiotics, pathogens and commensal microbes, these IECs are equipped with membrane-bound transporters as well as the ability to secrete specific protective proteins. In patients with active IBD (inflammatory bowel disease), the expression of these proteins, e.g. ABC (ATP-binding cassette) transporters such as ABCG2 (ABC transporter G2) and defensins, is decreased, thereby limiting the protection against various luminal threats. Correct ER (endoplasmic reticulum)-dependent protein folding is essential for the localization and function of secreted and membrane-bound proteins. Inflammatory triggers, such as cytokines and nitric oxide, can impede protein folding, which causes the accumulation of unfolded proteins inside the ER. As a result, the unfolded protein response is activated which can lead to a cellular process named ER stress. The protein folding impairment affects the function and localization of several proteins, including those involved in protection against xenobiotics. In the present review, we discuss the possible inflammatory pathways affecting protein folding and eventually leading to IEC malfunction in patients with active IBD.

STAT1, STAT6 and adenosine 3',5'-cyclic monophosphate (cAMP) signaling drive SOCS3 expression in inactive ulcerative colitis.

Ulcerative colitis (UC) is a chronic disease associated with long periods of quiescent disease followed by fulminant exacerbation. Imminent relapse in UC is associated with high mucosal expression of suppressor of cytokine signaling 3 (SOCS3); hence, knowledge of the mechanisms driving mucosal SOCS3 expression may provide important clues as to rational therapy. Thus, here we aim to characterize the molecular forces driving SOCS3 expression in the mucosal compartment, focusing on druggable pathways. The colon epithelial cell line Caco-2 was stimulated with interferon (IFN)-γ, interleukin (IL)-4 or prostaglandin E2 (PGE2) to allow correlations between SOCS3 expression with signal transducer and activator of transcription 1 (STAT1), STAT6 and adenosine 3′,5′-cyclic monophosphate (cAMP) signaling, respectively. The physiological relevance of the findings obtained was assessed by immunohistochemical staining for the activated forms of STAT1, STAT6, protein kinase A (PKA)-Cγ and cAMP response element-binding protein (CREB) in biopsies from inactive UC patients and controls. Stimulation with IFN-γ, IL-4 or PGE2 induced activation of STAT1, STAT6 and cAMP, respectively, in colonic cells, without any signs of concomitant STAT3 activation. Forced activation of all these signaling pathways was sufficient for SOCS3 expression. Biopsies from patients with inactive UC showed significant increase of phosphorylated STAT1 (p-STAT1) (p < 0.0001), p-STAT6 (p = 0.0001), p-PKA-Cγ (p = 0.0003) and p-CREB (p = 0.0025) expression compared with controls. STAT3-independent SOCS3 induction in inactive UC involves multiple proinflammatory signaling pathways and contradicts the usefulness of pathway-specific antiinflammatory drugs for preventing relapse. Our findings suggest that broad-spectrum antiinflammatory drugs are essential to counteract increases in SOCS3 expression and exacerbation of disease. Our results highlight the multifactorial nature of the factors that cause exacerbation in UC.

Dichotomal effect of space flight-associated microgravity on stress-activated protein kinases in innate immunity

Space flight strongly moderates human immunity but is in general well tolerated. Elucidation of the mechanisms by which zero gravity interacts with human immunity may provide clues for developing rational avenues to deal with exaggerated immune responses, e.g. as in autoimmune disease. Using two sounding rockets and one manned Soyuz launch, the influence of space flight on immunological signal transduction provoked by lipopolysaccharide (LPS) stimulation was investigated in freshly isolated peripheral blood monocytes and was compared to samples obtained from on-board centrifuge-loaded 1 g controls. The effect of microgravity on immunological signal transduction is highly specific, since LPS dependent Jun-N-terminal kinase activation is impaired in the 0 g condition, while the corresponding LPS dependent activation of p38 MAP kinase remains unaffected. Thus our results identify Jun-N-terminal kinase as a relevant target in immunity for microgravity and support using Jun-N-terminal kinase specific inhibitors for combating autoimmune disease.

Analysis of SHIP1 expression and activity in Crohn’s disease patients

Background SH2 domain containing inositol-5-phosphatase (SHIP1) is an important modulator of innate and adaptive immunity. In mice, loss of SHIP1 provokes severe ileitis resembling Crohn’s disease (CD), as a result of deregulated immune responses, altered cytokine production and intestinal fibrosis. Recently, SHIP1 activity was shown to be correlated to the presence of a CD-associated single nucleotide polymorphism in ATG16L1. Here, we studied SHIP1 activity and expression in an adult cohort of CD patients. Methods SHIP1 activity, protein and mRNA expression in peripheral blood mononuclear cells from CD patients in clinical remission were determined by Malachite green assay, Western blotting and qRT-PCR respectively. Genomic DNA was genotyped for ATG16L1 rs2241880. Results SHIP1 protein levels are profoundly diminished in a subset of patients; however, SHIP1 activity and expression are not correlated to ATG16L1 SNP status in this adult cohort. Conclusions Aberrant SHIP1 activity can contribute to disease in a subset of adult CD patients, and warrants further investigation.

P288 - Breast cancer resistance protein (BCRP/ABCG2) expression is reduced during active colitis and translocated in IBD-related neoplasia

compared to control samples, but TGF-b signalling was only significantly increased in the fibrotic muscle (Fig 3). An unexpected observation was the lack of a concomitant increase in inflamed or fibrotic muscle MMP-2 (Fig 4), in tissues in which collagen synthesis was increased compared to controls. Mucosal MMP-9, MMP-2, TNF-a and IL-1b, and muscle MMP-9 and IL-1b were increased compared to controls. TGF-b has previously been shown to stimulate collagen and MMP-2 genes concordantly, but from the novel finding that increased collagen synthesis occured without a similar increase in MMP-2 synthesis in fibrotic muscle tissue, and that phosphorylated smad2 was increased in fibrotic muscle, we propose that altered regulation of TGF-b signalling in fibrotic muscle contributes to the fibrosis. We also propose that increasing MMP-2 activity in patients with intestinal fibrosis may reduce the stricture, especially in early stage disease.