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Studying pancreatitis in mice, we found activation of digestive proteases to occur not only in acinar cells but also in macrophages that infiltrate pancreatic tissue. Activation of the proteases in macrophage occurs during endocytosis of zymogen-containing vesicles, and depends on pH and CTSB. This process involves macrophage activation via NF-κB-translocation, and contributes to systemic inflammation and severity of pancreatitis.

Emergency mobilization of neutrophil granulocytes (neutrophils) from the bone marrow (BM) is a key event of early cellular immunity. The hematopoietic cytokine granulocyte-colony stimulating factor (G-CSF) stimulates this process, but it is unknown how individual neutrophils respond in situ. We show by intravital 2-photon microscopy that a systemic dose of human clinical-grade G-CSF rapidly induces the motility and entry of neutrophils into blood vessels within the tibial BM of mice. Simultaneously, the neutrophil-attracting chemokine KC (Cxcl1) spikes in the blood. In mice lacking the KC receptor Cxcr2, G-CSF fails to mobilize neutrophils and antibody blockade of Cxcr2 inhibits the mobilization and induction of neutrophil motility in the BM. KC is expressed by megakaryocytes and endothelial cells in situ and is released in vitro by megakaryocytes isolated directly from BM. This production of KC is strongly increased by thrombopoietin (TPO). Systemic G-CSF rapidly induces the increased production of TPO in BM. Accordingly, a single injection of TPO mobilizes neutrophils with kinetics similar to G-CSF, and mice lacking the TPO receptor show impaired neutrophil mobilization after short-term G-CSF administration. Thus, a network of signaling molecules, chemokines, and cells controls neutrophil release from the BM, and their mobilization involves rapidly induced Cxcr2-mediated motility controlled by TPO as a pacemaker. IntroductionNeutrophils are the most abundant and, arguably, the most important leukocyte in the vertebrate immune system. Under normal conditions, human bone marrow (BM) produces ϳ 10 11 neutrophils per day. 1 In "danger situations" such as peripheral infections, the constant release of neutrophils can be dramatically increased within hours, a process termed danger or stress mobilization. 2 The hematopoietic cytokine granulocyte-colony stimulating factor (G-CSF) is central to the danger mobilization of neutrophils in both humans and mice. 3 However, although recombinant G-CSF has been used in clinical hematology for 20 years, the molecular mechanisms by which it mobilizes neutrophils are still not well understood.Neutrophils are restrained in the BM by the binding of their chemokine receptor Cxcr4 to the chemokine Cxcl12, which is expressed in a membrane-associated fashion by BM stromal cells. 4 There is evidence that G-CSF breaks the Cxcr4-Cxcl12 bond by activating neutrophil proteases, 5 thereby releasing neutrophils from the BM into the bloodstream. 3,6 However, several findings cannot be explained by the Cxcr4-Cxcl12 breakage concept alone. First, G-CSF can mobilize neutrophils in protease-deficient mice, arguing against the need for protease activation for this process. 7,8 Second, because neutrophil-specific deletion of Cxcr4 in mice results in much higher numbers of circulating neutrophils compared with wild-type animals, factors other than Cxcr4 must be involved in steering neutrophils into the BM blood sinuses (unless the process is passive). Finally, the specific Cxcr4-antagonist AMD3100 a...

The calcineurin inhibitor cyclosporine A and the mammalian target of rapamycin (mTOR) inhibitor, rapamycin, improve the course of AIP in MRL/Mp mice via different mechanisms. These findings further support the concept of autoreactive T cells as key players in the pathogenesis of AIP and suggest that cyclosporine A and rapamycin should be considered for treatment of AIP in humans.

The incidence of acute pancreatitis per 100,000 of population ranges from 5 to 80. Patients suffering from hemorrhagic-necrotizing pancreatitis die in 10-24% of cases. 80% of all cases of acute pancreatitis are etiologically linked to gallstone disease immoderate alcohol consumption. As of today no specific causal treatment for acute pancreatitis exists. Elevated C-reactive protein levels above 130,mg/L can also predict a severe course of acute pancreatitis. The essential medical treatment for acute pancreatitis is the correction of hypovolemia. Prophylactic antibiotics should be restricted to patients with necrotizing pancreatitis, infected necrosis or other infectious complications. However, as premature intracellular protease activation is known to be the primary event in acute pancreatitis. Severe acute pancreatitis is characterized by an early inflammatory immune response syndrome (SIRS) and a subsequent compensatory anti-inflammatory response syndrome (CARS) contributing to severity as much as protease activation does. CARS suppresses the immune system and facilitates nosocomial infections including infected pancreatic necrosis, one of the most feared complications of the disease. A number of attempts have been made to suppress the early systemic inflammatory response but even if these mechanisms have been found to be beneficial in animal models they failed in daily clinical practice.

ObjectivePancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies and is projected to be the second leading cause of cancer-related death by 2030. Despite extensive knowledge and insights into biological properties and genetic aberrations of PDAC, therapeutic options remain temporary and ineffective. One plausible explanation for the futile response to therapy is an insufficient and non-specific delivery of anticancer drugs to the tumour site.DesignSuperparamagnetic iron oxide nanoparticles (SPIONs) coupled with siRNA directed against the cell cycle-specific serine-threonine-kinase, Polo-like kinase-1 (siPLK1-StAv-SPIONs), could serve a dual purpose for delivery of siPLK1 to the tumour and for non-invasive assessment of efficiency of delivery in vivo by imaging the tumour response. siPLK1-StAv-SPIONs were designed and synthesised as theranostics to function via a membrane translocation peptide with added advantage of driving endosomal escape for mediating transportation to the cytoplasm (myristoylated polyarginine peptides) as well as a tumour-selective peptide (EPPT1) to increase intracellular delivery and tumour specificity, respectively.ResultsA syngeneic orthotopic as well as an endogenous cancer model was treated biweekly with siPLK1-StAv-SPIONs and tumour growth was monitored by small animal MRI. In vitro and in vivo experiments using a syngeneic orthotopic PDAC model as well as the endogenous LSL-KrasG12D, LSL-Trp53R172H, Pdx-1-Cre model revealed significant accumulation of siPLK1-StAv-SPIONs in PDAC, resulting in efficient PLK1 silencing. Tumour-specific silencing of PLK1 halted tumour growth, marked by a decrease in tumour cell proliferation and an increase in apoptosis.ConclusionsOur data suggest siPLK1-StAv-SPIONs with dual specificity residues for tumour targeting and membrane translocation to represent an exciting opportunity for targeted therapy in patients with PDAC.

Magnesium supplementation significantly reduces premature protease activation and the severity of pancreatitis, and antagonises pathological [Ca(2+)](i) signals. Nutritional magnesium deficiency increases the susceptibility of the pancreas towards pathological stimuli. These data have prompted two clinical trials on the use of magnesium in patients at risk for pancreatitis.

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