Determination of Mucoadhesion of Polyvinyl Alcohol Films to Human Intestinal Tissue.

The absorption of drugs with narrow absorption windows in the upper small intestine can be improved with a mucoadhesive drug delivery system such as enteric films. To predict the mucoadhesive behaviour in vivo, suitable in vitro or ex vivo methods can be performed. In this study, the influence of tissue storage and sampling site on the mucoadhesion of polyvinyl alcohol film to human small intestinal mucosa was investigated. Tissue from twelve human subjects was used to determine adhesion using a tensile strength method. Thawing of tissue frozen at -20 °C resulted in a significantly higher work of adhesion (p = 0.0005) when a low contact force was applied for one minute, whereas the maximum detachment force was not affected. When the contact force and time were increased, no differences were found for thawed tissue compared to fresh tissue. No change in adhesion was observed depending on the sampling location. Initial results from a comparison of adhesion to porcine and human mucosa suggest that the tissues are equivalent.

Visceral Surgery Profoundly Affects the Cellular and Humoral Components of the Anti-Tumour Immune Response in a Murine Pancreatic Adenocarcinoma Model.

(1) Background: Surgery is the most important element of multimodal treatment concepts in oncological patients, especially in the early stages of pancreatic tumours. While the influence of primary tumour resection on the immune status was analysed in several studies, the impact of tumour-unrelated visceral surgery on the tumour-bearing organism and on the primary tumour itself is not yet fully understood. (2) Methods: We combined a murine model of orthotopically implanted adenocarcinoma of the pancreas with the model of surgically-induced immune dysfunction (SID). Mortality and general condition including body weight were observed over a period of 28 days. Tumour growth was analysed by MRI scans on days 8 and 27 following tumour implantation. On day 28, the immune cell populations in the blood and spleen as well as the serum cytokines were quantified. (3) Results: SID results in a significant deterioration of the general condition and a reduced increase in the body weight of tumour-bearing mice compared to the control groups, while mortality and tumour growth rate were not influenced. The numbers of spleen macrophages and neutrophils were increased in tumour-bearing animals following SID. Furthermore, both macrophage and neutrophil levels were increased in the peripheral blood. (4) Conclusions: The presented results might contribute to the basic understanding of the interaction of tumour and immune system and could contribute to new approaches to immunotherapeutic strategies.

Sphingosine-1-Phosphate Receptor Type 4 (S1P4) Is Differentially Regulated in Peritoneal B1 B Cells upon TLR4 Stimulation and Facilitates the Egress of Peritoneal B1a B Cells and Subsequent Accumulation of Splenic IRA B Cells under Inflammatory Conditions.

BACKGROUND: Gram-negative infections of the peritoneal cavity result in profound modifications of peritoneal B cell populations and induce the migration of peritoneal B cells to distant secondary lymphoid organs. However, mechanisms controlling the egress of peritoneal B cells from the peritoneal cavity and their subsequent trafficking remain incompletely understood. Sphingosine-1-phosphate (S1P)-mediated signaling controls migratory processes in numerous immune cells. The present work investigates the role of S1P-mediated signaling in peritoneal B cell trafficking under inflammatory conditions. METHODS: Differential S1P receptor expression after peritoneal B cell activation was assessed semi­quantitatively using RT-PCR in vitro. The functional implications of differential S1P1 and S1P4 expression were assessed by transwell migration in vitro, by adoptive peritoneal B cell transfer in a model of sterile lipopolysaccharide (LPS)­induced peritonitis and in the polymicrobial colon ascendens stent peritonitis (CASP) model. RESULTS: The two sphingosine-1-phosphate receptors (S1PRs) expressed in peritoneal B cell subsets S1P1 and S1P4 are differentially regulated upon stimulation with the TLR4 agonist LPS, but not upon PMA/ionomycin or B cell receptor (BCR) crosslinking. S1P4 deficiency affects both the trafficking of activated peritoneal B cells to secondary lymphoid organs and the positioning of these cells within the functional compartments of the targeted organ. S1P4 deficiency in LPS-activated peritoneal B cells results in significantly reduced numbers of splenic innate response activator B cells. CONCLUSIONS: The S1P-S1PR system is implicated in the trafficking of LPS-activated peritoneal B cells. Given the protective role of peritoneal B1a B cells in peritoneal sepsis, further experiments to investigate the impact of S1P4-mediated signaling on the severity and mortality of peritoneal sepsis are warranted.

Murine Distal Colostomy, A Novel Model of Diversion Colitis in C57BL/6 Mice.

Diversion colitis (DC) is a frequent clinical condition occurring in patients with bowel segments excluded from the fecal stream as a result of a diverting enterostomy. The etiology of this disease remains ill-defined but appears to differ from that of classical inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. Research aimed to decipher the pathophysiological mechanisms leading to the development of this disease has been severely hampered by the lack of an appropriate murine model. This protocol generates a murine model of DC that facilitates the study of the immune system's role and its interaction with the microbiome in the development of DC. In this model using C57BL/6 animals, distal parts of the colon are excluded from the fecal stream by creating a distal colostomy, triggering the development of mild to moderate inflammation in the excluded bowel segments and reproducing the hallmark lesions of human DC with a moderate systemic inflammatory response. In contrast to the rat model, a large number of genetically-modified murine models on the C57BL/6 background are available. The combination of these animals with our model allows the potential roles of individual cytokines, chemokines, or receptors of bioactive molecules (e.g., interleukin (IL)-17; IL-10, chemokine CXCL13, chemokine receptors CXCR5 and CCR7, and the sphingosine-1-phosphate receptor 4) to be assessed in the pathogenesis of DC. The availability of congenic mouse strains on the C57BL/6 background largely facilitates transfer experiments to establish the roles of distinct cell types involved in the etiology of DC. Finally, the model offers the opportunity to assess the influences of local interventions (e.g., modification of the local microbiome or local anti-inflammatory therapy) on mucosal immunity in affected and non-affected bowel segments and the on systemic immune homeostasis.

S1P Signalling Differentially Affects Migration of Peritoneal B Cell Populations In Vitro and Influences the Production of Intestinal IgA In Vivo.

Introduction: Sphingosine-1-phosphate (S1P) regulates the migration of follicular B cells (B2 cells) and directs the positioning of Marginal zone B cells (MZ B cells) within the spleen. The function of S1P signalling in the third B cell lineage, B1 B cells, mainly present in the pleural and peritoneal cavity, has not yet been determined. Methods: S1P receptor expression was analysed in peritoneal B cells by real-time polymerase chain reaction (qPCR). The chemotactic response to S1P was studied in vitro. The role of S1P signalling was further explored in a s1p4-/- mouse strain. Results: Peritoneal B cells expressed considerable amounts of the S1P receptors 1 and 4 (S1P1 and S1P4, respectively). S1P1 showed differential expression between the distinct peritoneal B cell lineages. While B2 cells showed no chemotactic response to S1P, B1 B cells showed a migration response to S1P. s1p4-/- mice displayed significant alterations in the composition of peritoneal B cell populations, as well as a significant reduction of mucosal immunoglobulin A (IgA) in the gut. Discussion: S1P signalling influences peritoneal B1 B cell migration. S1P4 deficiency alters the composition of peritoneal B cell populations and reduces secretory IgA levels. These findings suggest that S1P signalling may be a target to modulate B cell function in inflammatory intestinal pathologies.

Deviation of the Fecal Stream in Colonic Bowel Segments Results in Increased Numbers of Isolated Lymphoid Follicles in the Submucosal Compartment in a Novel Murine Model of Diversion Colitis.

INTRODUCTION: Diversion colitis is a significant health problem due to its high incidence in patients with diverting enterostomy. This mucosal inflammation presents characteristic histopathological features allowing for the differentiation of this entity from other inflammatory bowel diseases. The pathophysiology of this disease remains ill-defined, in part due to the lack of appropriate animal models. The present study was performed in order to develop and characterize a murine model of diversion colitis. METHODS: A diverting loop colostomy was performed in C57BL/6 mice either in the ascending colon or in the transverse colon. Animals were assessed for clinical and histopathological parameters during short-term and long-term survival. RESULTS: Animals with a colostomy in the transverse colon showed a good long-term survival and developed a mild colitis in the bypassed bowel closely resembling the human pathology on a histopathological level. CONCLUSION: This model is a promising tool to further elucidate the pathomechanism leading to impaired mucosal homeostasis in bypassed colonic segments. Moreover, the establishment of the model in the C57BL/6 background allows the combination of this colitis model with various transgenic mouse strains to investigate the effect of locally deregulated mucosal immunity on systemic immune homeostasis and to develop specific therapeutic strategies.