TREM-1--expressing intestinal macrophages crucially amplify chronic inflammation in experimental colitis and inflammatory bowel diseases

Triggering receptor expressed on myeloid cells-1 (TREM-1) potently amplifies acute inflammatory responses by enhancing degranulation and secretion of proinflammatory mediators. Here we demonstrate that TREM-1 is also crucially involved in chronic inflammatory bowel diseases (IBD). Myeloid cells of the normal intestine generally lack TREM-1 expression. In experimental mouse models of colitis and in patients with IBD, however, TREM-1 expression in the intestine was upregulated and correlated with disease activity. TREM-1 significantly enhanced the secretion of relevant proinflammatory mediators in intestinal macrophages from IBD patients. Blocking TREM-1 by the administration of an antagonistic peptide substantially attenuated clinical course and histopathological alterations in experimental mouse models of colitis. This effect was also seen when the antagonistic peptide was administered only after the first appearance of clinical signs of colitis. Hence, TREM-1-mediated amplification of inflammation contributes not only to the exacerbation of acute inflammatory disorders but also to the perpetuation of chronic inflammatory disorders. Furthermore, interfering with TREM-1 engagement leads to the simultaneous reduction of production and secretion of a variety of pro-inflammatory mediators such as TNF, IL-6, IL-8 (CXCL8), MCP-1 (CCL2), and IL-1beta. Therefore, TREM-1 may also represent an attractive target for the treatment of chronic inflammatory disorders.

Inhibition by interferon-gamma of human mononuclear cell-mediated low density lipoprotein oxidation. Participation of tryptophan metabolism along the kynurenine pathway

In this study we examined the potential inhibition by interferon-gamma (IFN gamma) of the early stages of low density lipoprotein (LDL) oxidation mediated by human peripheral blood mononuclear cells (PBMC) and monocyte-derived macrophages (MDM) in Ham's F-10 medium supplemented with physiological amounts of L-tryptophan (Trp). We assessed LDL oxidation by measuring the consumption of LDL's major antioxidant (i.e., alpha-tocopherol) and targets for oxidation (cholesteryllinoleate and cholesterylarachidonate), together with the accumulation of cholesterylester hydroperoxides and the increase in relative electrophoretic mobility of the lipoprotein particle. Exposure of PBMC or MDM to IFN gamma induced the degradation of extracellular Trp with concomitant accumulation of kynurenine, anthranilic and 3-hydroxyanthranilic acid (3HAA) in the culture medium. Formation of 3HAA, but neither Trp degradation nor formation of kynurenine and anthranilic acid, was inhibited by low amounts of diphenylene iodonium (DPI) in a concentration-dependent manner. In contrast to oxidative Trp metabolism, exposure of human PBMC or MDM to IFN gamma failed to induce degradation of arginine, and nitrite was not detected in the cell supernatant, indicating that nitric oxide synthase was not induced under these conditions. Incubation of LDL in Trp-supplemented F-10 medium resulted in a time-dependent oxidation of the lipoprotein that was accelerated in the presence of PBMC or MDM but inhibited strongly in the presence of both cells and IFN gamma, i.e., when Trp degradation and formation of 3HAA were induced. In contrast, when IFN gamma was added to PBMC or MDM in F-10 medium that was virtually devoid of Trp, inhibition of cell-accelerated LDL oxidation was not observed. Exogenous 3HAA added to PBMC or purified monocytes in the absence of IFN gamma also strongly and in a concentration-dependent manner inhibited LDL oxidation. Selective inhibition of IFN gamma-induced formation of 3HAA by DPI caused reversion of the inhibitory action of this cytokine on both PBMC- and MDM-mediated LDL oxidation. These results show that IFN gamma treatment of human PBMC or MDM in vitro attenuates the extent of LDL oxidation caused by these cells, and indicate that Trp degradation with formation of 3HAA is a major contributing factor to this inhibitory activity.

Glucagon, catecholamine and pancreatic polypeptide secretion in type I diabetic recipients of pancreas allografts

Successful pancreas transplantation in type I diabetic patients restores normal fasting glucose levels and biphasic insulin responses to glucose. However, virtually no data from pancreas recipients are available relative to other islet hormonal responses or hormonal counterregulation of hypoglycemia. Consequently, glucose, glucagon, catecholamine, and pancreatic polypeptide responses to insulin-induced hypoglycemia and to stimulation with arginine and secretin were examined in 38 diabetic pancreas recipients, 54 type I diabetic nonrecipients, and 26 nondiabetic normal control subjects. Glucose recovery after insulin-induced hypoglycemia in pancreas recipients was significantly improved. Basal glucagon levels were significantly higher in recipients compared with nonrecipients and normal subjects. Glucagon responses to insulin-induced hypoglycemia were significantly greater in the pancreas recipients compared with nonrecipients and similar to that observed in control subjects. Glucagon responses to intravenous arginine were significantly greater in pancreas recipients than that observed in both the nonrecipients and normal subjects. No differences were observed in epinephrine responses during insulin-induced hypoglycemia. No differences in pancreatic polypeptide responses to hypoglycemia were observed when comparing the recipient and nonrecipient groups, both of which were less than that observed in the control subjects. Our data demonstrate significant improvement in glucose recovery after hypoglycemia which was associated with improved glucagon secretion in type I diabetic recipients of pancreas transplantation.

Effect of hydration status on cerebral blood flow and cerebrospinal fluid lactic acidosis in rabbits with experimental meningitis

The effects of hydration status on cerebral blood flow (CBF) and development of cerebrospinal fluid (CSF) lactic acidosis were evaluated in rabbits with experimental pneumococcal meningitis. As loss of cerebrovascular autoregulation has been previously demonstrated in this model, we reasoned that compromise of intravascular volume might severely affect cerebral perfusion. Furthermore, as acute exacerbation of the inflammatory response in the subarachnoid space has been observed after antibiotic therapy, animals were studied not only while meningitis evolved, but also 4-6 h after treatment with antibiotics to determine whether there would also be an effect on CBF. To produce different levels of hydration, animals were given either 50 ml/kg per 24 h of normal saline ("low fluid") or 150 ml/kg 24 h ("high fluid"). After 16 h of infection, rabbits that were given the lower fluid regimen had lower mean arterial blood pressure (MABP), lower CBF, and higher CSF lactate compared with animals that received the higher fluid regimen. In the first 4-6 h after antibiotic administration, low fluid rabbits had a significant decrease in MABP and CBF compared with, and a significantly greater increase in CSF lactate concentration than, high fluid rabbits. This study suggests that intravascular volume status may be a critical variable in determining CBF and therefore the degree of cerebral ischemia in meningitis.

The transcription factor IFN regulatory factor-4 controls experimental colitis in mice via T cell-derived IL-6

The proinflammatory cytokine IL-6 seems to have an important role in the intestinal inflammation that characterizes inflammatory bowel diseases (IBDs) such as Crohn disease and ulcerative colitis. However, little is known about the molecular mechanisms regulating IL-6 production in IBD. Here, we assessed the role of the transcriptional regulator IFN regulatory factor-4 (IRF4) in this process. Patients with either Crohn disease or ulcerative colitis exhibited increased IRF4 expression in lamina propria CD3+ T cells as compared with control patients. Consistent with IRF4 having a regulatory function in T cells, in a mouse model of IBD whereby colitis is induced in RAG-deficient mice by transplantation with CD4+CD45RB(hi) T cells, adoptive transfer of wild-type but not IRF4-deficient T cells resulted in severe colitis. Furthermore, IRF4-deficient mice were protected from T cell-dependent chronic intestinal inflammation in trinitrobenzene sulfonic acid- and oxazolone-induced colitis. In addition, IRF4-deficient mice with induced colitis had reduced mucosal IL-6 production, and IRF4 was required for IL-6 production by mucosal CD90+ T cells, which it protected from apoptosis. Finally, the protective effect of IRF4 deficiency could be abrogated by systemic administration of either recombinant IL-6 or a combination of soluble IL-6 receptor (sIL-6R) plus IL-6 (hyper-IL-6). Taken together, our data identify IRF4 as a key regulator of mucosal IL-6 production in T cell-dependent experimental colitis and suggest that IRF4 might provide a therapeutic target for IBDs.

Expeditious synthesis of 5,6,7 ,8-tetrahydro-imidazo[1,2-a ] pyrimidin-2-ones and 3,4,6,7 ,8,9-hexahydro-pyrimido[,2-a ] pyrimidin-2-ones

A convenient synthesis of new 5,6,7 ,8-tetrahydro-imidazo[ 1,2-a]pyrimidin-2-ones and 3,4,6,7 ,8,9-hexahydro-pyrimido[1 ,2a]pyrimidin-2- ones from the Baylis-Hillman adducts of acrylonitrile and their derivatives is described. A common strategy employed to achieve the syntheses of title compounds involved generation of diamines from different Baylis-Hillman derivatives followed by treatment with cyanogen bromide at reflux temperature to trigger a double intramolecular cyclization.

Synthesis of substituted 1H- and 3H-1-benzazepines: Rearrangement of 2-alkoxycarbonyl-1H-1-benzazepines to isoquinolines

The SnCl2-mediated reduction of nitro groups in 2-nitro-4-(2-nitro-benzylidene)-alkanoates and 4-nitro-2-(2-nitro-alkylidene)-alkanoates afforded via SN2′ reaction of ethyl nitroacetate and nitroethane with the acetyl derivatives of Baylis-Hillman adducts afforded by 2-nitro-substituted benzaldehydes leads to facile synthesis of substituted 1H-1-benzazepine and 3H-1-benzazepine. During the study an unprecedented rearrangement of 2-alkoxycarbonyl-1H-benzazepine to substituted isoquinoline has been observed.

Neighboring group effect: DBU-promoted ring transformation of substituted isoxazoles to substituted pyrroles

A novel DBU-promoted ring transformation of substituted isoxazoles to substituted pyrroles is described

Tributyltin hydride-mediated straightforward synthesis of a new isoxazolo-benzazulene ring system

Tributyltin hydride-mediated straightforward synthesis of a new isoxazolo-benzazulene system from the derivatives afforded by the Baylis-Hillman reaction of 3-(2-bromophenyl)-4-isoxazolecarbaldehydes is described

A Facile synthesis of 3-Methylene-4-aryl-1,3,4,5-tetrahydro-benzo[b][1,4] di-azepin-2-ones and 3-arylemethylene-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-ylamines

A simple and convenient synthesis of 3-methylene-4-aryl-1,3,4,5-tetrahydro-benzo[b][1,4] diazepin-2-ones was accomplished by the SN2 nucleophilic substitution of the acetates of Baylis-Hillman adducts of acrylate with 1,2-phenylenediamines followed by base-mediated intramolecular cyclization. On the other hand similar substrates derived from the Baylis-Hillman adducts of acrylonitrile via Pinner’s reaction leads to 3-arylmethylene-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-ylamines in good yields..