Transcriptional regulation of CXC-ELR chemokines KC and MIP-2 in mouse pancreatic acini

Abstract

Neutrophils and their chemoattractants, the CXC-ELR chemokines keratinocyte cytokine (KC) and macrophage inflammatory protein-2 (MIP-2), play a critical role in pancreatitis. While acute pancreatitis is initiated in acinar cells, it is unclear if these are a source of CXC-ELR chemokines. KC and MIP-2 have NF-κB, activator protein-1 (AP-1) sites in their promoter regions. However, previous studies have shown increased basal and reduced caerulein-induced AP-1 activation in harvested pancreatic tissue in vitro, which limits interpreting the caerulein-induced response. Moreover, recent studies suggest that NF-κB silencing in acinar cells alone may not be sufficient to reduce inflammation in acute pancreatitis. Thus the aim of this study was to determine whether acinar cells are a source of KC and MIP-2 and to understand their transcriptional regulation. Primary overnight-cultured murine pancreatic acini were used after confirming their ability to replicate physiological and pathological acinar cell responses. Upstream signaling resulting in KC, MIP-2 upregulation was studied along with activation of the transcription factors NF-κB and AP-1. Cultured acini replicated critical responses to physiological and pathological caerulein concentrations. KC and MIP-2 mRNA levels increased in response to supramaximal but not to physiological caerulein doses. This upregulation was calcium and protein kinase C (PKC), but not cAMP, dependent. NF-κB inhibition completely prevented upregulation of KC but not MIP-2. Complete suppression of MIP-2 upregulation required dual inhibition of NF-κB and AP-1. Acinar cells are a likely source of KC and MIP-2 upregulation during pancreatitis. This upregulation is dependent on calcium and PKC. MIP-2 upregulation requires both NF-κB and AP-1 in these cells. Thus dual inhibition of NF-κB and AP-1 may be a more successful strategy to reduce inflammation in pancreatitis than targeting NF-κB alone.

ADP-ribosylation Factor 1 Protein Regulates Trypsinogen Activation via Organellar Trafficking of Procathepsin B Protein and Autophagic Maturation in Acute Pancreatitis

“…Supraphysiologic caerulein induces numerous deleterious phenomena other than autophagy in acinar cells, including actin reorganization, blebbing (23,31), mitochondrial depolarization (28,55,56), sustained elevations in cytosolic calcium (55), and generation of inflammatory mediators (24,57). In our studies, BFA did not prevent up-regulation of inflammatory mediator mRNA (i.e.…”

Pancreatitis activates pancreatic apelin-APJ axis in mice

“…G-CSF and KC are important regulators of neutrophil homeostasis. G-CSF exerts a variety of trophic actions on neutrophils to increase their density, and KC is a key chemoattractant for neutrophils (2,31). The present study also shows that apelin administration during a 1-wk recovery period following CP induction reduced pancreatic MPO levels.…”

“…Neutrophil and macrophage infiltration is a major characteristic of human and experimental pancreatitis, resulting in parenchymal damage and a dysfunctional pancreas (2,31,42,50). In APKO mice subjected to two sequential episodes of AP, neutrophil recruitment was enhanced greatly compared with WT mice.…”

“…Our results show decrements in pancreatic IBs with NF-B activation. NF-B activation occurs in all experimental pancreatitis models (11,12,31,47); however, the functional role of NF-B activation during CP is less studied (50). A recent report shows that prolonged NF-B activation in a transgenic mouse model results in CP (17).…”

“…Objectives for the present study are as follows: 1) to define the influence of experimental AP and CP on expression levels of apelin and APJ in the mouse pancreas, 2) to examine the influence of apelin exposure on pancreatic neutrophil recruitment, serum chemoattractant levels, and pancreatic production of ECM-associated proteins during pancreatitis, 3) to examine the effects of apelin on PDGF-simulated proliferation and connective tissue growth factor (CTGF) production in cultured PSCs, and 4) because NF-B is an important transcription factor thought to play a major role in regulation of pancreatic inflammation and fibrosis during pancreatitis (11,12,17,31,47), to examine the influence of apelin exposure on pancreatic NF-B binding in mice with AP and CP.…”