Interobserver agreement of current and new proposed endoscopic scores for postoperative recurrence in Crohn's disease.

BACKGROUND AND AIMS: The modified Rutgeerts' score (mRS) is widely used for the assessment of endoscopic postoperative recurrence (ePOR) in Crohn's disease (CD) after ileocolic resection to guide therapeutic decisions. To improve the validity and prognostic value of this endoscopic assessment, two new scores have been proposed. This study assessed the interobserver agreement of the current (mRS) and new endoscopic scores for ePOR in CD. METHODS: Sixteen Dutch academic and non-academic IBD specialists assessed endoscopic videos (n=71) of postoperative CD patients (n=66) retrieved from nine Dutch centers. Each video was assessed for the degree of inflammation by four gastroenterologists using the mRS and the new proposed endoscopic score: REMIND score (separate score of anastomosis and neoterminal ileum) and updated Rutgeerts score (assessment of lesions at the anastomotic line, ileal inlet, ileal body and neoterminal ileum). In addition, lesions at the ileal body, ileal inlet, neoterminal ileum, colonic and/or ileal blind loop were separately assessed. Interobserver agreement was assessed using Fleiss' weighted kappa. RESULTS: Fleiss' weighted kappa for the mRS was 0.67 (95% confidence interval [CI] 0.59-0.74). The weighted kappa for the REMIND score was 0.73 (95% CI 0.65-0.80) for lesions in the neoterminal ileum and 0.46 (95% CI 0.35-0.58) for anastomotic lesions. The weighted kappa for the updated Rutgeerts' score was 0.69 (95% CI 0.62-0.77). The weighted kappa for lesions in the ileal body, ileal inlet, neoterminal ileum, colonic and ileal blind loop was 0.61 (95% CI 0.49-0.73), 0.63 (95% CI 0.54-0.72), 0.61 (95% CI 0.49-0.74), 0.83 (95% CI 0.62-1.00) and 0.68 (95% CI 0.46-0.89). CONCLUSION: The interobserver agreement of the mRS is substantial. Similarly, the interobserver agreement is substantial for the updated Rutgeerts' score. According to the REMIND score, the interobserver agreement was substantial for lesions in the neoterminal ileum, whereas only moderate for anastomotic lesions. Since therapeutic decisions in clinical practice are based on these assessments and these scores are used as outcome measure in clinical studies, further improvement of the interobserver agreement is essential.

Cumulative thiopurine dosing and keratinocyte skin cancer in inflammatory bowel disease: a case-control study.

BACKGROUND AND AIM: Patients with inflammatory bowel disease (IBD) treated with thiopurines are at increased risk of keratinocyte skin cancer (KSC). Most international guidelines recommend yearly dermatological screening of thiopurine-treated patients. Whether the association between the development of KSC and the use of thiopurines is dose-dependent remains unclear. The aim of this study was to investigate the association between the cumulative thiopurine dose and KSC development in patients with IBD which can be helpful to assist in further skin cancer risk stratification and personalization of screening recommendations in patients with IBD. METHODS: We performed a single-center case-control study, including patients with IBD with and without a history of KSC (cases and controls, respectively). The primary outcome was the association of cumulative azathioprine, mercaptopurine and thioguanine dose with KSC development. Univariable and multivariable logistic regression analyses were performed, the latter corrected for age and smoking, known risk factors of KSC. RESULTS: We included 50 cases and 150 controls, predominantly white population. Age and current azathioprine use were univariably significantly associated with KSC development. In multivariable logistic regression analyses, age at inclusion remained significantly associated. Cumulative doses of thiopurines (separate or combined) or duration of thiopurine use did not impact KSC risk, also after correcting for age and smoking. CONCLUSION: Cumulative thiopurine dose and duration did not show an association with KSC development. Future KSC risk stratification, based on all available KSC risk factors, may aid in selecting individuals who can benefit most from dermatologic screening programs.

Effectiveness of Mindfulness-Based Cognitive Therapy in reducing psychological distress and improving sleep in patients with Inflammatory Bowel Disease: study protocol for a multicentre randomised controlled trial (MindIBD).

BACKGROUND: Many patients with Inflammatory Bowel Diseases (IBD) suffer from psychological distress, fatigue and sleep disturbances, which are associated with reduced quality of life (QoL) and increased societal costs. Only limited psychosocial treatment options are available. As Mindfulness-Based Cognitive Therapy (MBCT) has demonstrated to improve psychological distress, QoL and sleep in other populations, MBCT might also be effective in patients with IBD. METHODS: The MindIBD study is a prospective, multicentre, randomised controlled trial comparing MBCT plus Treatment As Usual (TAU) versus TAU alone in a targeted number of 136 IBD patients in remission, aged 16 years and older with at least mild psychological distress (Hospital Anxiety and Depression Scale (HADS) total score ≥ 11). Primary outcome is reduction of psychological distress post-intervention, measured by the HADS. In addition, the effect of MBCT on sleep quality (including actigraphy and electroencephalography recordings), fatigue, disease activity, perceived disease control, QoL and positive mental health will be examined. Assessments will be conducted at baseline and at 3, 6, 9 and 12 months follow-up. Cost-effectiveness will be determined and a process evaluation will be conducted. DISCUSSION: This study will provide valuable insight into the clinical effect of MBCT on psychological distress, sleep quality, fatigue and QoL in IBD patients and into the cost-effectiveness. If effective, MBCT can be a valuable addition to the available psychosocial interventions for patients with IBD. Moreover, findings from this study may also be applicable in patients with other chronic conditions. TRIAL REGISTRATION: ClinicalTrials.gov: NCT04646785, registered on 30/11/2020.

Feasibility of Reduced Clinical Monitoring in Patients with Inflammatory Bowel Disease Treated with Thiopurine Therapy.

BACKGROUND: Outpatient visits and laboratory assessments are routinely scheduled every 3 to 4 months in thiopurine-treated patients with inflammatory bowel disease (IBD) to timely detect thiopurine-related adverse events (AEs). AEs that require therapy adjustment beyond 12 months of treatment are rare. AIM AND METHODS: This single-center prospective cohort study evaluated the safety of a reduced 6-monthly monitoring strategy in steroid-free patients with quiescent IBD on stable dose of azathioprine, mercaptopurine, or thioguanine monotherapy. The primary outcome was thiopurine-related AEs requiring therapy adjustments during a follow-up period of 24 months. Secondary outcomes included all AEs including laboratory toxicity, disease flares until 12 months, and the net monetary benefit from this strategy concerning IBD-related health care use. RESULTS: We enrolled 85 patients with IBD (median age 42 years, 61% Crohn's disease, 62% female), with a median disease duration of 12.5 years and median thiopurine treatment duration of 6.7 years. During follow-up, 3 patients (4%) ceased thiopurines due to AEs: recurrent infections, non-melanoma skin cancer, and gastrointestinal complaints (nausea, vomiting). At 12 months, 25 laboratory toxicities were observed (including 13% myelotoxicity, 17% hepatotoxicity); none required therapy adjustments and all were transient. A reduced monitoring strategy had a net benefit of €136 per patient. CONCLUSION: Three patients (4%) ceased thiopurine therapy due to thiopurine-related AEs, while no laboratory toxicity required therapy adjustments. Monitoring frequency of every 6 months seems feasible in patients with stable IBD on long-term (median duration > 6 years) maintenance thiopurine therapy and may contribute to reduced patient-burden and health care costs.

Exposure to Thioguanine During 117 Pregnancies in Women With Inflammatory Bowel Disease.

BACKGROUND: Safety of thioguanine in pregnant patients with inflammatory bowel disease [IBD] is sparsely recorded. This study was aimed to document the safety of thioguanine during pregnancy and birth. METHODS: In this multicentre case series, IBD patients treated with thioguanine during pregnancy were included. Data regarding disease and medication history, pregnancy course, obstetric complications, and neonatal outcomes were collected. RESULTS: Data on 117 thioguanine-exposed pregnancies in 99 women were collected. Most [78%] had Crohn's disease and the mean age at delivery was 31 years. In 18 pregnancies [15%], IBD flared. Obstetric and infectious complications were seen in 15% [n = 17] and 7% [n = 8] of pregnancies, respectively. Ten pregnancies [8.5%] resulted in a first trimester miscarriage, one in a stillbirth at 22 weeks of gestational age and one in an induced abortion due to trisomy 21. In total, 109 neonates were born from 101 singleton pregnancies and four twin pregnancies. One child was born with a congenital abnormality [cleft palate]. In the singleton pregnancies, 10 children were born prematurely and 10 were born small for gestational age. Screening for myelosuppresion was performed in 16 neonates [14.7%]; two had anaemia in umbilical cord blood. All outcomes were comparable to either the general Dutch population or to data from three Dutch cohort studies on the use of conventional thiopurines in pregnant IBD patients. CONCLUSION: In this large case series, the use of thioguanine during pregnancy is not associated in excess with adverse maternal or neonatal outcomes.

Thymoma-associated autoimmune enteropathy with colonic stricture: a diagnostic and histological challenge.

Thymoma-associated autoimmune enteropathy is a rare paraneoplastic syndrome that is characterized by severe chronic diarrhea, malabsorption, and specific histological findings. Because of its rarity, it is difficult to diagnose. We describe an adult patient with protracted diarrhea and weight loss that developed recurrent sepsis and progressive colonic stenosis due to thymoma-associated autoimmune enteropathy. Ultimately, the diagnosis thymoma-associated autoimmune enteropathy was established by characteristic intestinal histology, anti-enterocytes antibodies, and thorax imaging. Radical thymectomy was performed without improvement. Therapy with azathioprine and infliximab induced clinical remission with complete recovery of the colonic stenosis.

Ustekinuma b for Crohn's Disease: Two-Year Results of the Initiative on Crohn and Colitis (ICC) Registry, a Nationwide Prospective Observational Cohort Study.

AIMS: Ustekinumab is a monoclonal antibody that selectively targets p40, a shared subunit of the cytokines interleukin [IL]-12 and IL-23. It is registered for the treatment of inflammatory bowel diseases. We assessed the 2-year effectiveness and safety of ustekinumab in a real world, prospective cohort of patients with Crohn's disease [CD]. METHODS: Patients who started ustekinumab were prospectively enrolled in the nationwide Initiative on Crohn and Colitis [ICC] Registry. At weeks 0, 12, 24, 52 and 104, clinical remission Harvey Bradshaw Index≤ 4 points], biochemical remission (faecal calprotectin ≤ 200 µg/g and/or C-reactive protein ≤5 mg/L], perianal fistula remission, extra-intestinal manifestations, ustekinumab dosage and safety outcomes were determined. The primary outcome was corticosteroid-free clinical remission at week 104. RESULTS: In total, 252 CD patients with at least 2 years of follow-up were included. Of all included patients, the proportion of patients in corticosteroid-free clinical remission was 32.3% [81/251], 41.4% [104/251], 39% [97/249] and 34.0% [84/247] at weeks 12, 24, 52 and 104, respectively. In patients with combined clinical and biochemical disease activity at baseline [n = 122], the corticosteroid-free clinical remission rates were 23.8% [29/122], 35.2% [43/122], 40.0% [48/120] and 32.8% [39/119] at weeks 12, 24, 52 and 104, respectively. The probability of remaining on ustekinumab treatment after 52 and 104 weeks in all patients was 64.3% and 54.8%, respectively. The main reason for discontinuing treatment after 52 weeks was loss of response [66.7%]. No new safety issues were observed. CONCLUSION: After 104 weeks of ustekinumab treatment, one-third of CD patients were in corticosteroid-free clinical remission.

Clinical Outcomes of Covid-19 in Patients With Inflammatory Bowel Disease: A Nationwide Cohort Study.

BACKGROUND AND AIMS: The COVID-19 risk and disease course in inflammatory bowel disease [IBD] patients remains uncertain. Therefore, we aimed to assess the clinical presentation, disease course, and outcomes of COVID-19 in IBD patients. Second, we determined COVID-19 incidences in IBD patients and compared this with the general population. METHODS: We conducted a multicentre, nationwide IBD cohort study in The Netherlands and identified patients with COVID-19. First, we assessed the COVID-19 disease course and outcomes. Second, we compared COVID-19 incidences between our IBD study cohort and the general Dutch population. RESULTS: We established an IBD cohort of 34 763 patients. COVID-19 was diagnosed in 100/34 763 patients [0.29%]; 20/100 of these patients [20%] had severe COVID-19 defined as admission to the intensive care unit, mechanical ventilation, and/or death. Hospitalisation occurred in 59/100 [59.0%] patients and 13/100 [13.0%] died. All patients who died had comorbidities and all but one were ≥65 years old. In line, we identified ≥1 comorbidity as an independent risk factor for hospitalisation (odds ratio [OR] 4.20, 95% confidence interval [CI] 1.58-11.17,; p = 0.004). Incidences of COVID-19 between the IBD study cohort and the general population were comparable (287.6 [95% CI 236.6-349.7] versus 333.0 [95% CI 329.3-336.7] per 100000 patients, respectively; p = 0.15). CONCLUSIONS: Of 100 cases with IBD and COVID-19, 20% developed severe COVID-19, 59% were hospitalised and 13% died. A comparable COVID-19 risk was found between the IBD cohort [100/34 763 = 0.29%] and the general Dutch population. The presence of ≥1 comorbidities was an independent risk factor for hospitalisation due to COVID-19.

Comorbidity, not patient age, is associated with impaired safety outcomes in vedolizumab- and ustekinumab-treated patients with inflammatory bowel disease-a prospective multicentre cohort study.

BACKGROUND: Few data are available on the effects of age and comorbidity on treatment outcomes of vedolizumab and ustekinumab in inflammatory bowel disease (IBD). AIMS: To evaluate the association between age and comorbidity with safety and effectiveness outcomes of vedolizumab and ustekinumab in IBD. METHODS: IBD patients initiating vedolizumab or ustekinumab in regular care were enrolled prospectively. Comorbidity prevalence was assessed using the Charlson Comorbidity Index (CCI). Association between age and CCI, both continuously assessed, with safety outcomes (any infection, hospitalisation, adverse events) during treatment, and effectiveness outcomes (clinical response and remission, corticosteroid-free remission, clinical remission combined with biochemical remission) after 52 weeks of treatment were evaluated. Multivariable logistic regression was used to adjust for confounders. RESULTS: We included 203 vedolizumab- and 207 ustekinumab-treated IBD patients, mean age 42.2 (SD 16.0) and 41.6 (SD 14.4). Median treatment duration 54.0 (IQR 19.9-104.0) and 48.4 (IQR 24.4-55.1) weeks, median follow-up time 104.0 (IQR 103.1-104.0) and 52.0 weeks (IQR 49.3-100.4). On vedolizumab, CCI associated independently with any infection (OR 1.387, 95% CI 1.022-1.883, P = 0.036) and hospitalisation (OR 1.586, 95% CI 1.127-2.231, P = 0.008). On ustekinumab, CCI associated independently with hospitalisation (OR 1.621, 95% CI 1.034-2.541, P = 0.035). CCI was not associated with effectiveness, and age was not associated with any outcomes. CONCLUSIONS: Comorbidity - but not age - is associated with an increased risk of hospitalisations on either treatment, and with any infection on vedolizumab. This underlines the importance of comorbidity assessment and safety monitoring of IBD patients.

Clinical management of the most common extra-intestinal manifestations in patients with inflammatory bowel disease focused on the joints, skin and eyes.

Extra-intestinal manifestations (EIMs) of inflammatory bowel disease (IBD) occur frequently and contribute to morbidity and reduced quality of life. The musculoskeletal, ocular and cutaneous organ systems are frequently involved in IBD-related EIMs. By focusing on manifestations involving the joints, skin and eyes, this review will discuss the most common clinically relevant and burdensome EIMs that affect IBD patients, and strives for early recognition, adequate treatment and timely referral. For this purpose, we aimed to create a comprehensive overview on this topic, with the main focus on the treatment of reactive and associated EIMs, including spondyloarthropathies, pyoderma gangrenosum, erythema nodosum, psoriasis and anterior uveitis. The recently developed biologicals enable simultaneous treatment of inflammatory disorders. This review can be used as a helpful guide in daily clinical practice for physicians who are involved in the treatment of IBD patients.

Indian Hedgehog Suppresses a Stromal Cell-Driven Intestinal Immune Response.

BACKGROUND & AIMS: Upon intestinal epithelial damage a complex wound healing response is initiated to restore epithelial integrity and defend against pathogenic invasion. Epithelium-derived Indian Hedgehog (Ihh) functions as a critical sensor in this process. Signaling occurs in a paracrine manner because the receptor for Ihh is expressed only in the mesenchyme, but the exact Hedgehog target cell has remained elusive. The aim of this study was to elucidate further the nature of this target cell in the context of intestinal inflammation. METHODS: Hedgehog activity was modulated genetically in both cell type-specific and body-wide models and the resulting animals were analyzed for gene expression profiles and sensitivity for dextran sodium sulfate (DSS) colitis. To characterize the Hedgehog target cell, Gli1-CreERT2-Rosa26-ZsGreen animals were generated, which express ZsGreen in all Hedgehog-responsive cells. These cells were characterized using flow cytometry and immunofluorescence. RESULTS: Loss of Indian Hedgehog from the intestinal epithelium resulted in a rapid increase in expression of inflammation-related genes, accompanied by increased influx of immune cells. Animals with epithelium-specific deletion of Ihh or lacking the Hedgehog receptor Smoothened from Hedgehog target cells were more sensitive to DSS colitis. In contrast, specific deletion of Smoothened in the myeloid compartment did not alter the response to DSS. This suggests that Hedgehog signaling does not repress intestinal immunity through an effect on myeloid cells. Indeed, we found that Hedgehog-responsive cells expressed gp38, smooth muscle actin, and desmin, indicating a fibroblastic nature. Ihh signaling inhibited expression of C-X-C motif chemokine ligand 12 (CXCL12) in fibroblasts in vitro and in vivo, thereby impairing the recruitment of immune cells. CONCLUSIONS: We show that epithelium-derived Indian Hedgehog signals exclusively to fibroblasts in the intestine. Loss of Ihh leads to a rapid immune response with up-regulation of fibroblast-derived CXCL12, and migration of immune cells into the lamina propria.

Stromal Indian hedgehog signaling is required for intestinal adenoma formation in mice.

BACKGROUND & AIMS: Indian hedgehog (IHH) is an epithelial-derived signal in the intestinal stroma, inducing factors that restrict epithelial proliferation and suppress activation of the immune system. In addition to these rapid effects of IHH signaling, IHH is required to maintain a stromal phenotype in which myofibroblasts and smooth muscle cells predominate. We investigated the role of IHH signaling during development of intestinal neoplasia in mice. METHODS: Glioma-associated oncogene (Gli1)-CreERT2 and Patched (Ptch)-lacZ reporter mice were crossed with Apc(Min) mice to generate Gli1CreERT2-Rosa26-ZSGreen-Apc(Min) and Ptch-lacZ-Apc(Min) mice, which were used to identify hedgehog-responsive cells. Cyp1a1Cre-Apc (Apc(HET)) mice, which develop adenomas after administration of ß-naphthoflavone, were crossed with mice with conditional disruption of Ihh in the small intestine epithelium. Apc(Min) mice were crossed with mice in which sonic hedgehog (SHH) was overexpressed specifically in the intestinal epithelium. Intestinal tissues were collected and analyzed histologically and by immunohistochemistry and quantitative reverse-transcription polymerase chain reaction. We also analyzed levels of IHH messenger RNA and expression of IHH gene targets in intestinal tissues from patients with familial adenomatous polyposis (n = 18) or sessile serrated adenomas (n = 15) and normal colonic tissue from control patients (n = 12). RESULTS: Expression of IHH messenger RNA and its targets were increased in intestinal adenomas from patients and mice compared with control colon tissues. In mice, IHH signaling was exclusively paracrine, from the epithelium to the stroma. Loss of IHH from Apc(HET) mice almost completely blocked adenoma development, and overexpression of SHH increased the number and size of adenomas that developed. Loss of IHH from Apc(HET) mice changed the composition of the adenoma stroma; cells that expressed α-smooth muscle actin or desmin were lost, along with expression of cyclooxygenase-2, and the number of vimentin-positive cells increased. CONCLUSIONS: Apc mutant epithelial cells secrete IHH to maintain an intestinal stromal phenotype that is required for adenoma development in mice.

[Acute upper abdominal pain after excessive vomiting: Boerhaave's syndrome]. / Acute pijn in de bovenbuik na veelvuldig braken: Het Boerhaave-syndroom.

BACKGROUND: Boerhaave's syndrome is a spontaneous oesophageal rupture caused by excessive vomiting. Left untreated the mortality rate is high. Surgical intervention was always the treatment of first choice, but increasingly a minimally invasive approach involving the endoscopic placement of an oesophageal stent is being carried out. CASE STUDY: A 55-year-old man with no previous history presented at the Emergency Department complaining of pain in the upper abdomen that had come on suddenly after excessive vomiting. On CT scan Boerhaave's syndrome was diagnosed. An oesophageal stent was placed. The postoperative course was complicated by mediastinal and pleural abscesses for which surgical debridement was required. After 2 months the patient was discharged to a rehabilitation centre. CONCLUSION: Surgical intervention is indicated if a patient with Boerhaave's syndrome is haemodynamically unstable or has sepsis, and the diagnosis is made within 24 hours. In all other cases a minimally invasive approach involving antibiotics, pleural drainage and endoscopic stent placement should be considered.

Inactivation of Patched1 in mice leads to development of gastrointestinal stromal-like tumors that express Pdgfrα but not kit.

BACKGROUND & AIMS: A fraction of gastrointestinal stromal tumor (GIST) cells overexpress the platelet-derived growth factor receptor (PDGFR)A, although most overexpress KIT. It is not known if this is because these receptor tyrosine kinases have complementary oncogenic potential, or because of heterogeneity in the cellular origin of GIST. Little also is known about why Hedgehog (HH) signaling is activated in some GIST. HH binds to and inactivates the receptor protein patched homolog (PTCH). METHODS: Ptch was conditionally inactivated in mice (to achieve constitutive HH signaling) using a Cre recombinase regulated by the lysozyme M promoter. Cre-expressing cells were traced using R26R-LacZ reporter mice. Tumors were characterized by in situ hybridization, immunohistochemistry, immunoblot, and quantitative reverse-transcriptase polymerase chain reaction analyses. Cell transformation was assessed by soft agar assay. RESULTS: Loss of Ptch from lysozyme M-expressing cells resulted in the development of tumors of GIST-like localization and histology; these were reduced when mice were given imatinib, a drug that targets KIT and PDGFRA. The Hh signaling pathway was activated in the tumor cells, and Pdgfrα, but not Kit, was overexpressed and activated. Lineage tracing revealed that Cre-expressing intestinal cells were Kit-negative. These cells sometimes expressed Pdgfrα and were located near Kit-positive interstitial cells of Cajal. In contrast to KIT, activation of PDGFRA increased anchorage-independent proliferation and was required for tumor formation in mice by cells with activated HH signaling. CONCLUSIONS: Inactivation of Ptch in mice leads to formation of GIST-like tumors that express Pdgfrα, but not Kit. Activation of Pdgfrα signaling appears to facilitate tumorigenesis.

Hedgehog signalling stimulates precursor cell accumulation and impairs epithelial maturation in the murine oesophagus.

OBJECTIVE: In the intestine Hedgehog (Hh) signalling is directed from epithelium to mesenchyme and negatively regulates epithelial precursor cell fate. The role of Hh signalling in the oesophagus has not been studied in vivo. Here the authors examined the role of Hh signalling in epithelial homeostasis of oesophagus. DESIGN: The authors used transgenic mice in which the Hh receptor Patched1 (Ptch1) could be conditionally inactivated in a body-wide manner and mice in which Gli1 could be induced specifically in the epithelium of the skin and oesophagus. Effects on epithelial homeostasis of the oesophagus were examined using immunohistochemistry, in situ hybridisation, transmission electron microscopy and real-time PCR. Hh signalling was examined in patients with oesophageal squamous cell carcinoma (SCC) by quantitative real-time PCR. RESULTS: Sonic Hh is signalled in an autocrine manner in the basal layer of the oesophagus. Activation of Hh signalling resulted in an expansion of the epithelial precursor cell compartment and failure of epithelial maturation and migration. Levels of Hh targets GLI1, HHIP and PTCH1 were increased in SCC compared with normal tissue from the same patients. CONCLUSION: Here the authors find that Hh signalling positively regulates the precursor cell compartment in the oesophageal epithelium in an autocrine manner. Since Hh signalling targets precursor cells in the oesophageal epithelium and signalling is increased in SCCs, Hh signalling may be involved in oesophageal SCC formation.

Loss of Indian Hedgehog activates multiple aspects of a wound healing response in the mouse intestine.

BACKGROUND & AIMS: Indian Hedgehog (Ihh) is expressed by the differentiated epithelial cells of the small intestine and signals to the mesenchyme where it induces unidentified factors that negatively regulate intestinal epithelial precursor cell fate. Recently, genetic variants in the Hh pathway have been linked to the development of inflammatory bowel disease. METHODS: We deleted Ihh from the small intestinal epithelium in adult mice using Cyp1a1-CreIhh(fl/fl) conditional Ihh mutant mice. Intestines were examined by immunohistochemistry, in situ hybridization, and real-time polymerase chain reaction. RESULTS: Deletion of Ihh from the intestinal epithelium initially resulted in a proliferative response of the intestinal epithelium with lengthening and fissioning of crypts and increased Wnt signaling. The epithelial proliferative response was associated with loss of bone morphogenetic protein and Activin signaling from the epithelium of the villus and crypts, respectively. At the same stage we observed a substantial influx of fibroblasts and macrophages into the villus core with increased mesenchymal transforming growth factor-ß signaling and deposition of extracellular matrix proteins. Prolonged loss of Ihh resulted in progressive leukocyte infiltration of the crypt area, blunting and loss of villi, and the development of intestinal fibrosis. CONCLUSIONS: Loss of Ihh initiates several events that are characteristic of an intestinal wound repair response. Prolonged loss resulted in progressive inflammation, mucosal damage, and the development of intestinal fibrosis. Ihh is a signal derived from the superficial epithelial cells that may act as a critical indicator of epithelial integrity.

The absence of functional PI3Kgamma prevents leukocyte recruitment and ameliorates DSS-induced colitis in mice.

Phosphatidylinositol-3-kinase gamma (PI3Kgamma) is the major PI3K that is activated in response to chemoattractants. It is responsible for the migration of leukocytes from the bloodstream to sites of injury or infection. Constant migration of new leukocytes to the intestinal mucosa may be an important factor in maintenance of inflammation and tissue damage in inflammatory bowel disease (IBD). Reducing this influx, for example by inhibition of PI3Kgamma, might therefore be a potential goal for therapy. Here we investigated the role of PI3Kgamma in the migration of leukocytes to sites of intestinal inflammation. We induced colitis in mice with a point mutation that inactivates PI3Kgamma enzymatic activity ('kinase-dead') by oral administration of dextran sodium sulphate (DSS). Mice were treated with 1.5% DSS for 1 week and effects on cytokine production, leukocyte recruitment and disease severity were examined. Both clinical and histological parameters showed that the severity of colitis was significantly reduced in PI3Kgamma-kinase-dead mice compared to controls. Although mutant mice had a less severe colitis than controls they produced significantly more pro-inflammatory Th1 cytokines such as Il-12, Tnfalpha and Ifngamma and more Il-10. PI3Kgamma mutant mice showed increased numbers of resident macrophages and T cells in the colonic lamina propria in an unstressed condition but failed to recruit new leukocytes to the mucosa upon treatment with DSS despite the increased cytokine levels. These results suggest that PI3Kgamma plays a critical role in lamina propria leukocyte trafficking and that loss of PI3Kgamma-activity ameliorates DSS-induced colitis in mice.

Depletion of the colonic epithelial precursor cell compartment upon conditional activation of the hedgehog pathway.

BACKGROUND & AIMS: The intestinal epithelium is a homeostatic system in which differentiated cells are in dynamic equilibrium with rapidly cycling precursor cells. Wnt signaling regulates intestinal epithelial precursor cell fate and proliferation. Homeostatic systems exist by virtue of negative feedback loops, and we have previously identified the Hedgehog (Hh) pathway as a potential negative feedback signal in the colonic epithelium. Indian hedgehog (Ihh) is produced by the differentiated enterocytes and negatively regulates Wnt signaling in intestinal precursor cells. We studied the role of members of the Hh signaling family in the intestine using a conditional genetic approach. METHODS: We inactivated the Hh receptor Patched1 (Ptch1) in adult mice, resulting in constitutive activation of the Hh signaling pathway. Effects on colonic mucosal homeostasis were examined. Colon tissues were examined by immunohistochemistry, in situ hybridization, transmission electron microscopy, and real-time polymerase chain reaction. RESULTS: Ihh but not Sonic hedgehog (Shh) was expressed in colonic epithelium. Expression of Ptch1 and Gli1 was restricted to the mesenchyme. Constitutive activation of Hh signaling resulted in accumulation of myofibroblasts and colonic crypt hypoplasia. A reduction in the number of epithelial precursor cells was observed with premature development into the enterocyte lineage and inhibition of Wnt signaling. Activation of Hh signaling resulted in induction of the expression of bone morphogenetic proteins (Bmp) and increased Bmp signaling in the epithelium. CONCLUSIONS: Hh signaling acts in a negative feedback loop from differentiated cells via the mesenchyme to the colonic epithelial precursor cell compartment in the adult mouse.