A selective plasmin inhibitor, trans-aminomethylcyclohexanecarbonyl-L-(O-picolyl)tyrosine-octylamide (YO-2), induces thymocyte apoptosis

The treatment of rat thymocytes with YO-2, a novel inhibitor of plasmin, resulted in an increase in DNA fragmentation. DNA fragmentation was also induced by another YO compounds such as YO-0, -3, -4 and -5. These YO compounds are the inhibitor of plasmin activity. On the other hand, YO-1, -6 and -8 that hardly inhibit plasmin activity had no effect on DNA fragmentation. Analysis of fragmented DNA from thymocytes treated with YO-2 by agarose gel electrophoresis revealed that the compound caused internucleosomal DNA fragmentation. In addition, judging from a laser scanning microscopy, annexin V-positive and propidium iodide-negative cells were increased by the treatment of the cells with the compound. Moreover, chromatin condensation was observed in thymocytes treated with the compound. These results demonstrated that YO-2 induces thymocyte apoptosis. There seemed to be some correlation between the apoptosis induced by YO compounds and their plasmin inhibitory effect. However, because the other protease inhibitors including pepstatin A, leupeptin, AEBSF, DFP and E-64-d did not affect DNA fragmentation, YO compounds are likely to have unique mechanism on plasmin or to show the effect on the other plasmin-like proteases. The plasmin inhibitory activity may have an important role in YO-2-induced apoptosis. Furthermore, the stimulations of caspase-8, -9 and -3-like activities were observed in thymocytes treated with YO-2. These results suggest that YO-2 induces thymocyte apoptosis via activation of caspase cascade.     

Regulatory effects of deoxycholic acid, a component of the anti-inflammatory traditional Chinese medicine Niuhuang, on human leukocyte response to chemoattractants

Niuhuang is a commonly used Chinese traditional medicine with immunoregulatory and anti-inflammatory properties. Deoxycholic acid (DCA) is a major active constituent of Niuhuang. The reaction of human leukocytes to chemoattractants is an important part of the host immune response and also plays a crucial role in the development of inflammation. We, therefore, investigated the in vitro effects of DCA on human monocyte and neutrophil responses to classic chemoattractants [fMet-Leu-Phe (fMLP), complement fraction 5a (C5a)], CC chemokine [monocyte chemoattractant protein-1 (MCP-1/CCL2)], and/or CXC chemokines [stromal cell-derived factor-1 (SDF-1alpha/CXCL12), interleukin-8 (IL-8/CXCL8)]. The results showed that DCA significantly inhibited fMLP-induced monocyte and neutrophil chemotaxis and calcium mobilization, and also blocked the binding of [3H]fMLP and anti-formyl peptide receptor (FPR) monoclonal antibodies (mAb) to the cells. The inhibitory effects of DCA on calcium mobilization and anti-FPR-mAb binding to the receptor could be abrogated by washing DCA out of the cell suspension, suggesting that DCA blocked fMLP receptors via a steric hindrance mechanism, not via receptor internalization. DCA had no significant inhibitory effects on MCP-1-, SDF-1alpha-, or C5a-induced monocyte function, or C5a- or IL-8-induced neutrophil function. Taken together, our experimental results suggest that blockade of fMLP receptors may contribute to the anti-inflammatory effects of traditional medicine containing DCA.     

5-Hydroxyindole potentiates human alpha 7 nicotinic receptor-mediated responses and enhances acetylcholine-induced glutamate release in cerebellar slices

The effects of 5-hydroxyindole (5-HI) have been investigated on human alpha 7 nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes and GH4 cells, on native alpha 7 nAChRs expressed by IMR-32 cells and on alpha 7 nAChR-mediated events in mossy fibre-granule cell synapses in rat cerebellar slices. In oocytes expressing alpha 7 nAChRs, 5-HI potentiated sub-maximal, 60 micro M ACh-induced ion currents in a concentration-dependent manner, the threshold effective concentration being 30 micro M. 5-HI itself did not act as an agonist on alpha 7 nAChRs. A maximum potentiation of 12 times the control was observed at 20 mM 5-HI. The effect of 1 mM 5-HI on the concentration-response curve for ACh revealed that 5-HI increased the potency as well as the efficacy of ACh on alpha 7 nAChRs. 5-HI also potentiated alpha 7-mediated increases in intracellular free calcium levels in both mammalian cells heterologously expressing human alpha 7 nAChRs and in human IMR-32 neuroblastoma cells expressing native alpha 7 nAChRs. At mossy fibre-granule cell synapses, application of 1 mM ACh induced glutamate-evoked excitatory post-synaptic currents (EPSCs). Co-application of 1 mM 5-HI with 1 mM ACh further increased the frequency of the EPSCs. The ACh-induced release, as well as the 5-HI-induced enhancement of release, were blocked by 1-10 nM methyllycaconitine or 200 nM alpha-bungarotoxin, demonstrating that both effects were mediated by presynaptic alpha 7 nAChRs. The results demonstrate that responses mediated by alpha 7 nAChRs are strongly potentiated by 5-HI.     

Involvement of the peroxisome proliferator-activated receptor alpha in the immunomodulation caused by peroxisome proliferators in mice

Peroxisome proliferators (PPs) are a large class of structurally diverse chemicals, which includes drugs designed to improve the metabolic abnormalities linking hypertriglyceridemia to diabetes, hyperglycemia, insulin-resistance and atherosclerosis. We have recently demonstrated that exposure of rodents to potent PPs indirectly causes a number of immunomodulating effects, resulting in severe adaptive immunosuppression. Since the peroxisome proliferator-activated receptor alpha (PPARalpha) plays a central role in mediating the pleiotropic responses exerted by PPs, we have compared here the immunomodulating effects of the PPs perfluorooctanoic acid (PFOA) and Wy-14,643 in wild-type and PPARalpha-null mice. The reductions in spleen weight and in the number of splenocytes caused by PP treatment in wild-type mice was not observed in PPARalpha-null mice. Furthermore, the reductions in thymus weight and in the number of thymocytes were potently attenuated in the latter animals. Similarly, the dramatic decreases in the size of the CD4(+)CD8(+) population of cells in the thymus and in the number of thymocytes in the S and G2/M phases of the cell cycle observed in wild-type mice administered PPs were much less extensive in PPARalpha-null mice. Finally, in contrast to the case of wild-type animals, the response of splenocytes isolated from the spleen of PP-treated PPARalpha-null mice to appropriate T- or B-cell activators in vitro was not reduced. Altogether, these data indicate that PPARalpha plays a major role in the immunomodulation caused by PPs. The possible relevance of these changes to the alterations in plasma lipids also caused by PPs is discussed.     

Interleukin-1beta converting enzyme (caspase-1) in intestinal inflammation

An imbalance of T helper cell type 1 (Th1) versus type 2 (Th2) polarization in favor of Th1 cell subsets appears to be a key pathogenic mechanism in chronic inflammatory bowel disease (IBD), in particular in Crohn's disease. The interferon gamma-inducing factor interleukin (IL)-18 acts in strong synergism with the Th1 polarizing cytokine IL-12. Recent studies provide evidence for the participation of IL-18 in the pathogenesis of IBD: IL-18 expression is increased in inflamed lesions of Crohn's disease patients and neutralization of IL-18 in different models of experimental colitis resulted in a dramatic amelioration of disease severity. IL-18 and IL-1beta are cleaved and thereby activated by the interleukin-1beta converting enzyme (ICE). Activation of ICE also occurs during different types of infectious colitis, and ICE expression and subsequent release of IL-1beta and IL-18 significantly contribute to intestinal inflammation. ICE knockout mice as well as mice treated with the ICE inhibitor pralnacasan are protected against experimental mucosal inflammation. Thus, inhibition of ICE represents an intriguing new target that requires further investigation in animal models.     

Basal levels and patterns of anticancer drug-induced activation of nuclear factor-kappaB (NF-kappaB), and its attenuation by tamoxifen,dexamethasone, and curcumin in carcinoma cells

Nuclear factor-kappaB (NF-kappaB) has been implicated in the development of drug resistance in cancer cells. We systematically examined the baseline levels of NF-kappaB activity of representative carcinoma cell lines, and the change of NF-kappaB activity in response to a challenge with four major anticancer drugs (doxorubicin, 5-fluorouracil, cisplatin, and paclitaxel). We found that the basal level of NF-kappaB activity was heterogeneous and roughly correlated with drug resistance. When challenged with various drugs, all the cell lines examined responded with a transient activation of NF-kappaB which then declined to basal level despite variation in the concentration of the agent and the timing of the treatment. In contrast to tumor necrosis factor-alpha (TNF-alpha), which activates NF-kappaB in minutes, NF-kappaB activation induced by anticancer drugs usually occurred more than 1hr after stimulation. A gradual increase of total NF-kappaB and its nuclear translocation, and cytoplasmic translocation of nuclear IkappaBalpha and its degradation were involved in this process. In particular, when cells were pretreated with common biologic modulators such as tamoxifen, dexamethasone, and curcumin, the doxorubicin-induced NF-kappaB activation was attenuated significantly. This inhibition may play a role in sensitizing cancer cells to chemotherapeutic drugs. This study has demonstrated that activation of NF-kappaB is a general cellular response to anticancer drugs, and the mechanism of activation appears to be distinct from that induced by TNF-alpha. These observations may have implications for improving the efficacy of systemic chemotherapy for cancer patients.     

Epidemiology,implications and mechanisms underlying drug-induced weight gain in psychiatric patients

Body weight gain frequently occurs during drug treatment of psychiatric disorders and is often accompanied by increased appetite or food craving. While occurrence and time course of this side effect are difficult to predict, it ultimately results in obesity and the morbidity associated therewith in a substantial part of patients, often causing them to discontinue treatment even if it is effective. This paper reviews the available epidemiological data on the frequency and extent of weight gain associated with antidepressant, mood-stabilizing, and antipsychotic treatment. Possible underlying pathomechanisms are discussed with special attention to central nervous control of appetite including the role of leptin and the tumor necrosis factor system. Metabolic alterations induced by drug treatment such as type 2 diabetes mellitus and the metabolic syndrome are also considered. Weight gain appears to be most prominent in patients treated with some of the second generation antipsychotic drugs and with some mood stabilizers. Marked weight gain also frequently occurs during treatment with most tricyclic antidepressants, while conventional antipsychotics typically induce only slight to moderate weight gain. Serotonin reuptake inhibitors may induce weight loss during the first few weeks, but some of them induce weight gain during long-term treatment. Several antidepressant and antipsychotic drugs are identified which reliably do not cause weight gain or even reduce weight. Based on these insights, countermeasures to manage drug-induced weight gain are suggested.     

Local expression of tumor necrosis factor-alpha and interleukin-10 on wound healing of intestinal anastomosis during endotoxemia in mice

BACKGROUND: This study aimed to evaluate the integrity of anastomotic wound healing after digestive surgery under septic conditions and define the participation of local expression of tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) around the anastomotic segment. MATERIALS AND METHODS: Experimental animals were divided into lipopolysaccharide (LPS) and control groups, which had either LPS or normal saline solution injected into the peritoneal cavity 24 h before transection and anastomosis of the colon. Anastomotic bursting pressure (ABP) and tissue hydroxyproline concentration (HP) were measured as indicators of wound healing. Immunohistochemical staining for TNF-alpha and IL-10 on tissue samples obtained from the anastomotic segment were examined 1, 6, and 24 h after the operation. The reactive cells were counted under light microscopy. RESULTS: ABP and HP were significantly lower in the LPS group than in the control group 7 days after surgery. In the LPS group, TNF-alpha expression increased about threefold over that in the control group 1 h after the operation. TNF-alpha-reactive cells were observed until 24 h after the operation in the LPS group, but not in the control group. On the other hand, IL-10 was not expressed in the control group during the observed period, whereas IL-10 was observed 24 h after the operation in the LPS group. CONCLUSIONS: It is suggested that anastomotic wound healing was impaired after the digestive surgery in animals treated with intraperitoneal LPS, and that local expression of TNF-alpha and IL-10 at the anastomotic site acts as an inhibitory factor in the wound healing process.