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Pancreatic cancer is known for its tumor microenvironment (TME), which is rich in stromal and immune cells supporting cancer growth and therapy resistance. In particular, tumor-associated macrophages (TAMs) are known for their angiogenesis- and metastasis-promoting properties, which lead to the failure of conventional therapies for pancreatic cancer. Hence, treatment options targeting TAMs are needed. The C-C chemokine receptor type 4 (CCR4) is critical for immune cell recruitment into the TME, and in this paper we explore the effects of its genetic or immunotherapeutic blockade in pancreatic-cancer-bearing mice. Murine PDA6606 pancreatic cancer cells and murine peritoneal macrophages were used for in vitro migration assays. In vivo, a syngeneic, orthotropic pancreatic cancer model was established. Tumor growth and survival were monitored under prophylactic and therapeutic application of a CCR4 antagonist (AF-399/420/18025) in wildtype (CCR4wt) and CCR4-knockout (CCR4−/−) mice. Immune infiltration was monitored in tumor tissue sections and via flow cytometry of lysed tumors. PDA6606 cells induced less migration in CCR4−/− than in CCR4wt macrophages in vitro. Pancreatic TAM infiltration was higher, and survival was reduced in CCR4wt mice compared to CCR4−/− mice. Antagonizing CCR4 in wildtype mice revealed similar results as in CCR4−/− mice without antagonization. Prophylactic CCR4 antagonist application in wildtype mice was more efficient than therapeutic antagonization. CCR4 seems to be critically involved in TAM generation and tumor progression in pancreatic cancer. CCR4 blockade may help prolong the relapse-free period after curative surgery in pancreatic cancer and improve prognosis.
Introduction: Splenic B cells exhibit a high expression of the G protein-coupled sphingosine-1-phosphate (S1P) receptor type 4 (S1PR4). Little is known about the functional relevance of S1PR4 expression on those cells.
Methods: In this study, S1PR4-deficient mice were used to study the role of S1PR4-mediated S1P signaling in B cell motility in vitro and for the maintenance of the splenic architecture under steady state conditions as well as in polymicrobial abdominal sepsis in vivo. Finally, the impact of S1PR4 deficiency on antibody production after immunization with T cell dependent antigens was assessed.
Results: Loss of S1PR4 resulted in minor alterations of the splenic architecture concerning the presence of B cell follicles. After sepsis induction, the germinal center response was severely impaired in S1PR4-deficient animals. Splenic B cells showed reduced motility in the absence of S1PR4. However, titres of specific antibodies showed only minor reductions in S1PR4-deficient animals.
Discussion: These observations suggest that S1P signaling mediated by S1PR4 modifies chemokine-induced splenic B cell chemotaxis, thus modulating splenic microarchitecture, GC formation and T-cell dependent antibody production.
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.
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. Sphingosine1-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 semi-quantitatively 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.
Abstract
(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.
Background: Despite the growing concern over its potentially severe side effects and considerable economic burden, stress ulcer prophylaxis (SUP) is still frequently prescribed to patients in medical non-intensive care units. Recent data indicate that the situation is similar in surgical departments. Currently, data on the concepts within and regulation of routine SUP practice in surgical departments are sparse. The present study was designed to examine the current practice of SUP in Mecklenburg West Pomerania, Germany, and to identify possible reasons for the dissociation of medical literature and clinical practice. Methods: A questionnaire-based survey was conducted to elucidate current SUP practices in surgical departments of acute care hospitals in Mecklenburg Western Pomerania, Germany. Results: In most surgical departments (68%), a standard operating procedure (SOP) for SUP had not been developed. In departments with an existing SOP, 47.6% of responding medical staff members (MSM) with prescribing authority did not know of its existence. Of the MSMs aware of the existence of an SUP-SOP, only 42.9% indicated that they were familiar with its content. Critical re-evaluation of SUP indications upon transfer from the intensive care unit (ICU) to the general hospital ward (GHW) and before hospital discharge was performed frequently or systematically by only about half of the responding MSMs. Discussion: In the face of continued massive over-prescription of SUP in the perioperative routine, the development of easy-to-use local guidelines and their strict implementation in the clinical routine, as well as intensified medial education on this subject, may be effective tools to reduce acid-suppressive medication (ASM) associated side effects and economic burden.