Fat necrosis generates proinflammatory halogenated lipids during acute pancreatitis.

OBJECTIVE: To evaluate the generation of halogenated fatty acids in the areas of fat necrosis during acute pancreatitis and to evaluate the effects of these molecules on the ensuing inflammatory process. BACKGROUND: Lipid mediators derived from adipose tissue have been implicated in the progression of acute pancreatitis, although their precise role remains unknown. METHODS: Acute pancreatitis was induced in rats by intraductal infusion of 3.5% sodium taurocholate. Fatty acid chlorohydrins (FA-Cl) were measured in adipose tissue, ascitic fluid, and plasma by mass spectrometry. Chlorohydrins were also instilled in the rats' peritoneal cavity, and their effects on peritoneal macrophages activation and in systemic inflammation were evaluated. Finally, they have also been measured in plasma from human patients with acute pancreatitis. RESULTS: Induced acute pancreatitis results in a substantial release not only of free fatty acids but also of the chlorohydrins of both oleic and linoleic acids from adipose tissue. In plasma, only the chlorohydrin of oleic acid was detected. Administration of 250-µM lipid chlorohydrins, which is the concentration found in ascitic fluid, induces the expression of TNFα and interleukin-1ß in peritoneal macrophages and increases the systemic inflammatory response in pancreatitis. Finally, increased concentrations of oleic acid chlorohydrin have been found in plasma of human patients with pancreatitis. CONCLUSIONS: During acute pancreatitis, adipose tissue release FA-Cl, which exacerbate the systemic inflammatory response.

Expression of the tyrosine kinase discoidin domain receptor 1 (DDR1) in human central nervous system myelin.

During development of the mouse brain, the protein kinase discoidin domain receptor 1 (DDR1) is present prenatally in neurons of the proliferative areas, and postnatally, DDR1 expression is no longer detected in neurons, but a spatial-temporal expression pattern in oligodendrocytes that overlaps with the dynamics of the myelination process is detected. Notably, oligodendrocytic DDR1 expression is upregulated in mice during experimentally induced remyelination. Recently, we demonstrated that DDR1 expression is high in human brain and that there is an association between the gene and schizophrenia in a case-control study. However, data regarding expression of DDR1 in the human brain are scarce. Here, we describe the expression pattern of DDR1 in the human adult cerebral cortex. Using several immunohistological techniques and in situ hybridization, we identified DDR1 in the following: a) myelin, b) capillary endothelial cells in the gray as well as white matter, and c) in the soma of some oligodendrocytes and astrocytes in the white matter. The most important overall finding in this study was that DDR1 is present in myelin and is expressed by oligodendrocyte cells. We detected the presence of DDR1 mRNA and protein in myelin and observed that DDR1 co-localized with the classical myelin basic protein (MBP). Moreover, we found a strong positive correlation between expression levels of DDR1 and two myelin-associated genes, myelin-associated glycoprotein (MAG) and oligodendrocyte transcription factor 2 (OLIG2). These observations suggest that DDR1 could be an important constituent of myelin. Because defects in myelination are linked to several mental disorders such as schizophrenia, the function of DDR1 in the process of myelination warrants further investigation.

Release of inflammatory mediators by adipose tissue during acute pancreatitis.

Obesity and lipid metabolism are associated with the severity of acute pancreatitis. Fat necrosis appears in the severe acute pancreatitis as a consequence of the release of lipolytic enzymes, but its potential role on the progression of the disease is unclear. In this study, we have examined the role of white adipose tissue as a source of inflammatory mediators that can promote systemic inflammation during experimental taurocholate-induced acute pancreatitis in rats. The inflammatory status and the expression of TNFalpha, iNOS, adiponectin and IL-10 were determined in necrotic and non-necrotic areas of adipose tissue. Samples of adipose tissue were also used to induce the activation of macrophages in vitro. Finally, the release of TNFalpha to mesenterial vessels surrounded by necrotic or non-necrotic fat was evaluated in ex vivo perfused mesenterium. A strong inflammatory infiltrate was observed in the border between necrotic and non-necrotic areas of adipose tissue. In these areas, high expression of TNFalpha and iNOS and a reduced expression of IL-10 were observed, while adiponectin showed only a moderate increase. Necrotic fat strongly activates peritoneal macrophages in vitro. Mesenterial areas with fat necrosis release to the vascular vessels significantly increased amounts of TNFalpha when compared to vessels without necrosis. Altogether, these results indicate that adipose tissue inflammation is a process secondary to acute pancreatitis but also contributes to the generation of mediators potentially involved in the induction of the systemic inflammatory response. In particular, the areas of fat necrosis are important sources of inflammatory mediators.

Discoidin domain receptor 1, a tyrosine kinase receptor, is upregulated in an experimental model of remyelination and during oligodendrocyte differentiation in vitro.

The discoidin domain receptor (DDR1) is highly expressed in oligodendrocytes during the neurodevelopmental myelination process and is genetically associated to schizophrenia. In this study, we aimed to further assess the involvement of DDR1 in both remyelination and oligodendrocyte differentiation. In the mouse model of demyelination-remyelination induced by oral administration of cuprizone, in situ hybridization showed an upregulation of the DDR1 gene in three different white matter areas (corpus callosum, dorsal fornix, and external capsule) during the remyelination period. Moreover, real time reverse transcriptase polymerase chain reaction showed that the increase in DDR1 messenger RNA (mRNA) was strongly correlated with the number of DDR1-positive cells in the corpus callosum (Spearman coefficient = 0.987, P = 0.013). Cells positive for DDR1 mRNA were also positive for oligodendrocyte markers (OLIG2, carnosine, and APC) but not for markers of oligodendrocyte precursors (NG2), myelin markers (CNPase), microglia (CD11b), or reactive glia (GFAP). Differentiation of a human oligodendroglial cell line, HOG16, was associated with an increase in mRNA expression of DDR1 and several myelin proteins (MBP and MOBP) but not other proteins (APC and CNPase). Here, we demonstrate that DDR1 is upregulated in vitro and in vivo when oligodendrocyte myelinating machinery is activated. Further studies are needed to identify the specific molecular pathway.

Serum paraoxonase undergoes inhibition and proteolysis during experimental acute pancreatitis.

Oxidative stress has a primary role in the pathogenesis of severe acute pancreatitis. Then, the antioxidant capacity is a critical factor in the progression of this disease. Serum paraoxonase-1 (PON1) is an esterase associated with high-density lipoprotein, which clinical interest resides in its ability to prevent or limit the lipid oxidation. The aim of this study was to investigate changes in PON1 activity in the early stages of acute pancreatitis and to find out if its alteration is related with the severity of the disease. To this purpose, we used an experimental model of taurocholate-induced mild and severe acute pancreatitis. Our results showed that serum activity and PON1 concentration decreased 18 h after the induction of a severe acute pancreatitis. In vitro analysis revealed that incubation with oxidized lipids obtained from pancreatitis samples results in the inactivation of the enzyme in a concentration-dependent manner. In addition to oxidative inactivation, we observed by Western blot, an immunoreactive band suggestive of proteolytic degradation of the enzyme, altogether indicating that during severe acute pancreatitis, there is a significant decrease in serum PON1 activity. This decrease is related with inactivation of the enzyme by oxidized lipids, probably followed by proteolytic degradation of the enzyme.

Concurrent exposure to perfluorooctane sulfonate and restraint stress during pregnancy in mice: effects on postnatal development and behavior of the offspring.

The combined effects of maternal restraint stress and perfluorooctane sulfonate (PFOS) on postnatal development and behavior of the offspring were assessed in mice. Thirty-four plug positive females were randomly divided into two groups. Animals were given by gavage 0 and 6 mg PFOS/kg/day on gestation days 12-18. One-half of the animals in each group was subjected to restraint stress (30 min per session, three sessions per day) during the same period. Neither restraint nor PFOS exposure significantly modified maternal food or water consumption. Pups of dams exposed to 6 mg/kg of PFOS showed a reduced body weight on postnatal days 4 and 8. Moreover, PFOS exposure induced some delay in developmental landmarks and neuromotor maturation. Maternal restraint stress reduced activity in an open-field when combined with 6 mg PFOS/kg/day. In addition, in males prenatal restraint stress impaired motor coordination in a rotarod. The current results indicate that concurrent exposure to PFOS and restraint stress during pregnancy induces opposite effects on developmental parameters in the pups. These effects consist in a general delayed maturation trend induced by PFOS exposure, and a general accelerated maturation pattern induced by prenatal stress. Interactive effects between PFOS and maternal stress were observed in young adult mice. These effects consisted mainly in a diminished activity in an open-field test.

Behavioral deficits in the cuprizone-induced murine model of demyelination/remyelination.

The neurotoxicant cuprizone has been used extensively to create a mouse model of demyelination. However, the effects on behavior of cuprizone treatment have not been previously reported. We have analyzed the behavioral changes of mice given a diet containing 0.2% cuprizone for 6 weeks followed by 6 weeks of recovery. Behavior was assessed using a range of tests: the functional observation battery, the open-field test and the rota-rod test. Concurrent with the start of demyelination, at 3 and 4 weeks of 0.2% cuprizone treatment, the animals exhibited an increase in central nervous system activity and an inhibited anxiogenic response to the novelty challenge test. At 5 weeks of treatment (the period of maximal demyelination) equilibrium was altered and sensorimotor reactivity was also affected. Further, rota-rod analysis demonstrated that the treated group had poorer motor co-ordination than control animals. This effect was not reversed 6 weeks after cuprizone withdrawal. The animals in the recovery period also exhibited difficulties in the rota-rod progressive learning task. Our results indicate that behavioral deficits follow the course of demyelination-remyelination induced by administration of 0.2% cuprizone, and that some of the changes persist even after 6 weeks on normal diet.