A36 INVESTIGATING TYPE 1 REGULATORY T CELLS AS A THERAPY FOR INFLAMMATORY BOWEL DISEASE USING A MOUSE MODEL OF ACUTE INTESTINAL EPITHELIAL DAMAGE

Background

Inflammatory bowel disease (IBD) affects an estimated 270,000 people in Canada and is rapidly increasing in prevalence. All patients have relapsing disease, and a subset of individuals do not respond to current treatments. Further, there are no approved treatment options in Canada that reverse IBD-induced intestinal fibrosis. We have previously shown type 1 regulatory cells (Tr1s) are capable of suppressing inflammatory macrophages, promote barrier function of human intestinal epithelial cells, and induce differentiation of mucin-producing goblet cells. We hypothesize that Tr1 cells can prevent inflammatory damage and fibrosis in an mouse model of acute gut damage.

Purpose

We hypothesize that Tr1 cells can prevent inflammatory damage and fibrosis in an mouse model of gut damage. Here we evalute the therapeutic potential of Tr1 cells in an model of acute intestinal epithelial damage.

Method

Tr1 cells were isolated and expanded from CD4⁺ CD44^high FOXP3^- cells. Their phenotype was characterized by flow cytometry and cytokine secretion was measured via ELISA. WT B6 mice were given 2% DSS in H₂O for 7 days, followed by H₂O alone for 7 days. Prior to DSS treatment, mice were sub-lethally irradiated to facilitate engraftment, and given I.P. injections of PBS or 0.5 – 2 x 10⁶ Tr1 cells. Mice weights and health scores were recorded daily. At the endpoint, blood, spleen, and mesenteric lymph nodes were analyzed for Tr1 cell engraftment (or lack thereof) for each mouse. Complete white blood counts were performed for each mouse. Additionally, proximal, medial, and distal portions of the ileum were processed for histologic scoring.

Result(s)

Tr1 cells isolated from CD4⁺ CD44^high FOXP3^- cells produce high levels of IL-10 following stimulation (>35,000 pg/ml/1 x 10⁵ cells). Additionally, these cells express high levels of Tr1 markers CD49b and Lag-3. Optimization experiments indicated no significant differences between mice irradiated and given DSS and mice only given DSS (no irradiation). Our results suggest no significant differences in inflammatory cell infiltrate scores between control and Tr1 treated mice. However, gut architecture scores appeared to improve with increasing Tr1 doses. Further, weight change improved with Tr1 treatment, as compared to PBS controls. Interestingly, Tr1 treatment appeared to decrease total eosinophil and neutrophil counts from peripheral blood.

Conclusion(s)

Our initial findings indicate Tr1 adoptive transfer prior to acute damage via DSS improves gut damage and weight loss.

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CIHR

Disclosure of Interest

None Declared

A8 REPEATED SUBMERGENCE OF AIR-LIQUID INTERFACE COLONOID CULTURES IMPAIRS INFLAMMATORY AND REGENERATIVE RESPONSES

Background

Damage in the intestinal epithelium is repaired via de-differentiation of mature intestinal epithelial cells to a stem-like state. Indeed, literature has primarily focused on acute forms of intestinal damage, but there is a lack of models to study how intestinal stem cells function after chronic injury, such as in inflammatory bowel disease (IBD). A previous report found that growth of mouse intestinal organoids in air-liquid interface (ALI) follows by submergence caused differentiation and reversible injury, but this has not been demonstrated in human cells or with repeated cycles of injury. Understanding how chronic damage alters human intestinal stem cell fate and function is imperative to developing novel therapies that repair the epithelium in people with IBD

Aims

To develop a robust in vitro model to differentiate and damage human intestinal epithelial cells, with or without the addition of bacterial flagellin to mimic pathogen exposure.

Methods

Human colonoid monolayers were seeded on Transwell inserts for 10 days until fully confluent and then differentiated by removing the apical media to create ALI growth conditions for 7 days. To induce damage, media was added to the apical side of the Transwell, with or without the addition of flagellin in the basolateral compartment. Following submergence induced damage, the apical media was removed and collected for chemokine analysis, and the cells were grown back in ALI for 3 days to recover them from injury. This cycle was repeated 5 times to induce chronic damage. Cells were collected for qPCR analysis, immunofluorescence imaging, RNA sequencing and DNA methylation analysis

Results

Repeated rounds of damage impaired the ability of intestinal epithelial cells (IECs) to respond to TLR stimulation (a decrease in basolateral IL-8 with each round), likely due to a decrease in TLR signaling pathways, as demonstrated by GSEA and qPCR. Chronic submergence damage led to an increase in differentiation of cells expressing MUC2, SLC26a3 and CHGA, and a decrease in stemness as shown by qPCR for BMI1, HOPX, and LGR5. After several rounds of damage, colonoid monolayers were unable to regrow as monolayers after passaging, likely due to a decrease in YAP signaling. We also identified mRNA expression and DNA methylation changes in genes associated with IBD and colon cancer.

Conclusions

We have developed a novel chronic damage model of recurrent IEC injury, which possibly mimics pathologies seen in people with inflammatory bowel disease. This model can be used to understand how chronic damage alters the ability of IECs to respond to pathogens and regenerate to repair and protect the epithelium from further damage.

Funding Agencies

CCC

Hybrid multistep approach to mega-aortic syndrome: the Lupiae technique

OBJECTIVES

Several techniques have been described for the treatment of thoraco-abdominal aneurysms in patients with mega-aortic syndrome (MAS), but the incidence of stroke, spinal cord injury and endoleaks remains significant. We present the mid-term results of a new hybrid, multistep technique to treat patients with MAS.

METHODS

From November 2005 to November 2012, 118 patients with MAS underwent surgical repair of thoracic and thoraco-abdominal aneurysms with the Lupiae technique. Fifty-five patients presented chronic aneurysms and 63 patients Type A acute dissections. Eighty-three patients underwent ascending aorta and arch replacement with a multibranched Dacron graft and epiaortic vessels rerouting (thoracic Lupiae procedure). Twenty patients had the thoracic Lupiae procedure plus partial visceral debranching (coeliac trunk and superior mesenteric artery [SMA]) through an upper mini-laparotomy. Fifteen patients had the thoracic Lupiae procedure plus a complete visceral debranching (coeliac trunk, SMA and renal arteries) using a second multibranched Dacron graft to replace the infrarenal aorta. All the patients with chronic aneurysms and 34 of 63 patients with Type A dissections underwent implant of endovascular stent grafts.

RESULTS

In-hospital mortality was 8.4%. No patients had stroke or spinal cord injury. The incidence of temporary renal failure was 5.2%. No patients presented endoleaks immediately and at follow-up CT scans. No death or reoperation occurred during the follow-up.

CONCLUSIONS

These results evidence that the Lupiae technique is a safe and effective option for the treatment of patients with MAS, achieving the complete exclusion of thoraco-abdominal aneurysms and of the residual false lumen in patients with acute aortic dissections.

Experimental evidence of flow destabilization in a two-dimensional bidisperse foam

Liquid foam flows in a Hele-Shaw cell were investigated. The plug flow obtained for a monodisperse foam is strongly perturbed in the presence of bubbles whose sizes are larger than the average bubble size by an order of magnitude, at least. Above a velocity threshold, the large bubbles migrate faster than the mean flow. We evidence experimentally this instability and, in the case of a single large bubble, we compare the large bubble velocity to the prediction deduced from scaling arguments. In the case of a bidisperse foam, an attractive interaction between large bubbles induces segregation and the large bubbles organize themselves in columns oriented along the flow.

Epidemiological typing of Legionella pneumophila with ribotyping. Report of two clinical cases

The ribotyping method, adapted to the strains of Legionella pneumophila in our possession, was tested in two separate cases of legionellosis and in the associated finding of Legionella pneumophila in the water, from different sources, with which these patients had come into contact. Determination of the serogroup enabled us to carry out a preliminary analysis of the strains, which was then confirmed by application of the ribotyping procedure: the ribosomal profile of the strains found in the two patients correspond to that of the strains isolated from the water with which they had come into contact. These results provide important information concerning the probable sources of infection involved in these two cases of Legionnaires' disease. We consider ribotyping to be a very useful tool, which is easy and simple to perform and is applicable to the Legionella genus as the method of choice for epidemiological studies.

[Progress and problems in hospital infections: exemplified by pneumonia]

Nosocomial pneumonias have various etiologies and their development depends mainly on the underlying condition of the patients. Intubated patients are prone to development of bacterial pneumonia from the oropharyngeal or gastric flora. Prevention relies on reducing exogenous as well as endogenous colonization of the bronchotracheal tree: avoidance of cross-contamination, maintenance of a physiological gastric pH and, possibly, selective digestive decontamination. Neutropenic patients may develop invasive aspergillus infection. Prevention depends on appropriate air filtration. Patients with cellular immunodeficiency are susceptible to various agents. Prevention of legionella depends on control of the water and ventilation systems. The prevention of cytomegalovirus infection includes the screening of blood products for certain patients and, in some cases, the administration of hyperimmune gammaglobulins and possibly ganciclovir. Even though Pneumocystis carinii pneumonia is thought to be due to reactivation, recent evidence suggests that transmission may occur between patients and therefore appropriate respiratory isolation is advisable. Finally, nosocomial tuberculosis is an increasing problem in which control depends on early diagnosis and treatment of patients as well as on appropriate air exchange in particular rooms of the hospital. In conclusion, the prevention of nosocomial pneumonia includes numerous measures which largely depend on the type of microorganisms.

Anxiety and depression in 100 female geriatric inpatients. A psychopathological study

50 anxious and 50 depressed female geriatric inpatients aged 70 and above were assessed with a semistructured interview focusing on the patient's experience of her illness and hospital admission and on the doctor-patient relationship. Each interview was completed by psychodynamic evaluations and a clinical assessment. The psychopathological findings suggested the distinction of four groups of patients characterized by different psychological reaction profiles: patients with anxiety reaction only, anxious patients with some depressive reactions, depressive-dependent and depressive-resigned patients. These profiles were related to age: anxiety was more frequent among the younger patients while severe depression (resigned depression) prevailed among the oldest age-group (80 years and above). Sociological, psychological and psychotherapeutic implications are discussed.