Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin-dependent diabetes mellitus (IDDM) is characterized by the T cell-mediated destruction of insulin-producing beta cells. Accordingly, APCs, such as macrophage, have also been shown to be important in the disease process. However, the role(s) of dendritic cells (DCs) that exhibit potent APC function remains undefined in IDDM. Here we demonstrate that DCs derived from nonobese diabetic (NOD) mice, a model for IDDM, are more sensitive to various forms of stimulation compared with those from C57BL/6 and BALB/c mice, resulting in increased IL-12 secretion. This property is a consequence of hyperactivation of NF-kappaB, a transcription factor known to regulate IL-12 gene expression. Specifically, NOD DCs exhibit persistent hyperactivation of both IkappaB kinase and NF-kappaB in response to stimuli, in addition to selective degradation of IkappaBepsilon. Transfection of NOD DCs with a modified form of IkappaBalpha significantly reduced IL-12 secretion, suggesting that hyperactivation of NF-kappaB was in part responsible for increased IL-12 production. An enhanced capacity of NOD DCs to secrete IL-12 would be expected to contribute to the development of pathogenic Th1 (Tc1) cells during the diabetogenic response.
 ...
PMID:Dendritic cells from nonobese diabetic mice exhibit a defect in NF-kappa B regulation due to a hyperactive I kappa B kinase. 1146 66

We report a mouse model for the spontaneous development of autoimmune diabetes: the 3A9 T cell receptor (TCR) transgenic mouse, which contains T cells that recognize the 52 - 61 family of hen egg-white lysozyme (HEL) peptides in the context of MHC class II I-A(k) molecules, was bred to the ILK3 mouse, that expresses HEL protein via the rat insulin promoter (RIP). Despite partial tolerance of 3A9 T cells in ILK3 mice, spontaneous diabetes developed in 64 % of 3A9xILK3 mice by 20 weeks of age. We provide evidence that APC from peri-pancreatic nodes have a large content of peptide-MHC complex and stimulate 3A9 T cells. We also report that cross presentation of HEL from beta cells to APC is 26-fold more efficient than presentation of soluble HEL. We previously reported on a biochemical margin of safety, based on the observation that activation of naive 3A9 T cells required 100-fold more peptide-MHC complexes than required for deletion of 3A9 thymocytes. We speculate that the high local density of autologous peptide-MHC complexes can be a determining factor that leads to the activation of autoreactive CD4 T cells and, consequently, to the development of autoimmunity.
 ...
PMID:The level of peptide-MHC complex determines the susceptibility to autoimmune diabetes: studies in HEL transgenic mice. 1174 64

We have recently demonstrated that dendritic cells (DC) prepared from nonobese diabetic (NOD) mice, a spontaneous model for insulin-dependent diabetes mellitus, exhibit elevated levels of NF-kappaB activation upon stimulation. In the current study, we investigated the influence of dysregulation of NF-kappaB activation on the APC function of bone marrow-derived DC prepared from NOD vs BALB/c and nonobese diabetes-resistant mice. NOD DC pulsed with either peptide or virus were found to be more efficient than BALB/c DC at stimulating in vitro naive Ag-specific CD8+ T cells. The T cell stimulatory capacity of NOD DC was suppressed by gene transfer of a modified form of IkappaBalpha, indicating a direct role for NF-kappaB in this process. Furthermore, neutralization of IL-12(p70) to block autocrine-mediated activation of DC also significantly reduced the capacity of NOD DC to stimulate T cells. Despite a reduction in low molecular mass polypeptide-2 expression relative to BALB/c DC, no effect on proteasome-dependent events associated with the NF-kappaB signaling pathway or Ag processing was detected in NOD DC. Finally, DC from nonobese diabetes-resistant mice, a strain genotypically similar to NOD yet disease resistant, resembled BALB/c and not NOD DC in terms of the level of NF-kappaB activation, secretion of IL-12(p70) and TNF-alpha, and the capacity to stimulate T cells. Therefore, elevated NF-kappaB activation and enhanced APC function are specific for the NOD genotype and correlate with the progression of insulin-dependent diabetes mellitus. These results also provide further evidence indicating a key role for NF-kappaB in regulating the APC function of DC.
 ...
PMID:Elevated NF-kappaB activation in nonobese diabetic mouse dendritic cells results in enhanced APC function. 1175 62

Recently, a newly identified human HERV-K18 like endogenous retrovirus (IDDMK(1,2)22) has been associated to the etiology of type I diabetes (IDDM). Although the exact mechanism remains unclear, it was postulated that the 3' end ORF product of the env gene of IDDMK(1,2)22 would trigger a V beta 7-specific human T cell expansion leading to their infiltration in the pancreas of afflicted patients and to the autoimmune destruction of the insulin-producing beta cells. Since then, such superantigen (SAg)-like activity as well as the association between the IDDMK(1,2)22 virus and IDDM pathogenesis have been challenged. To further characterize functionally the putative IDDMK(1,2)22-encoded SAg, we have cloned from human DNA the identical 462bp ORF sequence originally described. The IDDMK(1,2)22 ORF fragment was transfected in the same human B cell line (Raji) originally used as APC to demonstrate the V beta 7 specificity. The immunostimulatory potential of IDDM ORF was tested on murine T cell hybridomas and compared to the well-characterized mouse mammary tumor virus Mtv7 SAg transfected in the same conditions. A panel of 16 T cell hybridomas encompassing 14 different V betas was analyzed. We have failed to detect IDDMK(1,2)22-induced IL-2 production from any of these hybridomas, even those bearing the murine V beta 1 mV beta 1, V beta 4 or V beta 10 TcR beta chains which are most closely related to the human V beta 7 (hV beta 7). Our results suggest that IDDMK(1,2)22 ORF is devoid of superantigenic activity as defined by classical criteria.
 ...
PMID:Human endogenous retrovirus IDDMK(1,2)22 and mouse mammary tumor virus superantigens differ in their ability to stimulate murine T cell hybridomas. 1184 50

LT97, a permanent cell line consisting of epithelial cells with an early premalignant genotype was established from small colorectal polyps. LT97 cells have lost both alleles of the APC tumour suppressor gene. In addition, they carry a mutated Ki-ras oncogene, while TP53 is normal. LT97 growth characteristics are thus representative of early adenomas. They had to be passaged as multicellular aggregates indicating a dependency of survival on cell-cell contact and in accordance with their premalignant genotype were not capable of growth in soft agar. LT97 cells did express both the EGF-receptor and small amounts of TGF(alpha) establishing an autocrine growth or survival pathway. However, in spite of autocrine TGF(alpha) production, growth was strongly dependent on exogenous growth factors--mainly EGF, insulin and HGF. Inhibition of the EGF-receptor kinase induced apoptosis at an IC(50) concentration of 4 micromolar indicating that TGF(alpha) activated survival pathways in the early adenoma cell.
 ...
PMID:Cells obtained from colorectal microadenomas mirror early premalignant growth patterns in vitro. 1220 77

Activation of PPARgamma by synthetic ligands, such as thiazolidinediones, stimulates adipogenesis and improves insulin sensitivity. Although thiazolidinediones represent a major therapy for type 2 diabetes, conflicting studies showing that these agents can increase or decrease colonic tumors in mice have raised concerns about the role of PPARgamma in colon cancer. To analyze critically the role of this receptor, we have used mice heterozygous for Ppargamma with both chemical and genetic models of this malignancy. Heterozygous loss of PPARgamma causes an increase in beta-catenin levels and a greater incidence of colon cancer when animals are treated with azoxymethane. However, mice with preexisting damage to Apc, a regulator of beta-catenin, develop tumors in a manner insensitive to the status of PPARgamma. These data show that PPARgamma can suppress beta-catenin levels and colon carcinogenesis but only before damage to the APC/beta-catenin pathway. This finding suggests a potentially important use for PPARgamma ligands as chemopreventative agents in colon cancer.
 ...
PMID:APC-dependent suppression of colon carcinogenesis by PPARgamma. 1237 Apr 29

Type 1 diabetes is characterized by a chronic inflammatory response resulting in the selective destruction of the insulin-producing beta cells. We have previously demonstrated that dendritic cells (DCs) prepared from nonobese diabetic (NOD) mice, a model for spontaneous type 1 diabetes, exhibit hyperactivation of NF-kappaB resulting in an increased capacity to secrete proinflammatory cytokines and stimulate T cells compared with DCs of nondiabetic strains of mice. In the current study, the activational status of NF-kappaB and its role in regulating the APC function of macrophages (Mphi) prepared from NOD, nonobese resistant (NOR), and BALB/c mice was investigated. Independent of the stimulus, splenic and bone marrow-derived Mphi prepared from NOD mice exhibited increased NF-kappaB activation relative to NOR and BALB/c Mphi. This hyperactivation was detected for different NF-kappaB complexes and correlated with increased IkappaBalpha degradation. Furthermore, increased NF-kappaB activation resulted in an enhanced capacity of NOD vs NOR or BALB/c Mphi to secrete IL-12(p70), TNF-alpha, and IL-1alpha, which was inhibited upon infection with an adenoviral recombinant encoding a modified form of IkappaBalpha. In contrast, elevated NF-kappaB activation had no significant effect on the capacity of NOD Mphi to stimulate CD4(+) or CD8(+) T cells in an Ag-specific manner. These results demonstrate that in addition to NOD DCs, NOD Mphi exhibit hyperactivation of NF-kappaB, which correlates with an increased ability to mediate a proinflammatory response. Furthermore, NF-kappaB influences Mphi APC function by regulating cytokine secretion but not T cell stimulation.
 ...
PMID:NF-kappa B hyperactivation has differential effects on the APC function of nonobese diabetic mouse macrophages. 1257 41

Peroxisome proliferator activated receptors (PPARs) are a family of related receptors implicated in a diverse array of biological processes. There are 3 main isotypes of PPARs known as PPARalpha, PPARbeta and PPARgamma and each is organized into domains associated with a function such as ligand binding, activation and DNA binding. PPARs are activated by ligands, which can be both endogenous such as fatty acids or their derivatives, or synthetic, such as peroxisome proliferators, hypolipidaemic drugs, anti-inflammatory or insulin-sensitizing drugs. Once activated, PPARs bind to DNA and regulate gene transcription. The different isotypes differ in their expression patterns, lending clues on their function. PPARalpha is expressed mainly in liver whereas PPARgamma is expressed in fat and in some macrophages. Activation of PPARalpha in rodent liver is associated with peroxisome proliferation and with suppression of apoptosis and induction of cell proliferation. The mechanism by which activation of PPARalpha regulates apoptosis and proliferation is unclear but is likely to involve target gene transcription. Similarly, PPARgamma is involved in the induction of cell growth arrest occurring during the differentiation process of fibroblasts to adipocytes. However, it has been implicated in the regulation of cell cycle and cell proliferation in colon cancer models. Less in known concerning PPARbeta but it was identified as a downstream target gene for APC/beta-catenin/T cell factor-4 tumor suppressor pathway, which is involved in the regulation of growth promoting genes such as c-myc and cyclin D1. Marked species and tissue differences in the expression of PPARs complicate the extrapolation of pre-clinical data to humans. For example, PPARalpha ligands such as the hypolipidaemic fibrates have been used extensively in the clinic over the past 20 years to treat cardiovascular disease and side effects of clinical fibrate use are rare, despite the observation that these compounds are rodent carcinogens. Similarly, adverse clinical responses have been seen with PPARgamma ligands that were not predicted by pre-clinical models. Here, we consider the response to PPAR ligands seen in pre-clinical models of efficacy and safety in the context of human health and disease.
 ...
PMID:Advances in understanding the regulation of apoptosis and mitosis by peroxisome-proliferator activated receptors in pre-clinical models: relevance for human health and disease. 1262 71

Gateways to clinical trials is a guide to the most recent clinical trials in current literature and congresses. The data in the following tables has been retrieved from the Clinical Studies knowledge area of Prous Science Integrity, the drug discovery and development portal, http://integrity.prous.com. This issue focuses on the following selection of drugs: 5A8; Agomelatine, alefacept, almotriptan, anakinra, APC-8015, atazanavir, atomoxetine hydrochloride, azimilide hydrochloride; Bicifadine; Cannabidiol, caspofungin acetate, CAT-213, CGP-51901, ciclesonide, cipamfylline; Darbepoetin alfa, desloratadine, dibotermin alfa, DX-9065a; Ecogramostim, efalizumab, eletriptan, eniluracil, EPI-KAL2, erlosamide, ertapenem sodium, etilevodopa, etoricoxib, ezetimibe; Fosamprenavir calcium, fosamprenavir sodium, fumagillin; Gadofosveset sodium, gefitinib, gemtuzumab ozogamicin; HSPPC-96, human papillomavirus vaccine; Icatibant Id-KLH, imatinib mesylate, INS-37217, iodine (I131) tositumomab; LAS-34475, levobupivacaine hydrochloride, levocetirizine, linezolid, 131I-lipiodol, lonafarnib, lopinavir, LY-450108; Magnetites, MBI-594AN, melagatran, melatonin, mepolizumab, mycophenolic acid sodium salt; NC-100100; 1-Octanol, omalizumab, omapatrilat, onercept; PEG-filgrastim, (PE)HRG21, peginterferon alfa-2a, peginterferon alfa-2b, pleconaril, pneumococcal 7-valent conjugate vaccine, prasterone; Ranelic acid distrontium salt, rasagiline mesilate, reslizumab, rFGF-2, rhOP-1, rosuvastatin calcium, roxifiban acetate; Sitaxsentan sodium, sodium lauryl sulfate; Tadalafil, telithromycin, tenofovir disoproxil fumarate, tipranavir, TMC-114, tucaresol; Valdecoxib, voriconazole; Ximelagatran; Zofenopril calcium, zosuquidar trihydrochloride.
 ...
PMID:Gateways to clinical trials. 1274 28

HLA-DM stabilizes peptide-receptive class II alphabeta dimers and facilitates the capture of high affinity peptides, thus influencing the peptide repertoire presented by class II molecules. Variations in DM levels may therefore have a profound effect on the antigenic focus of T cell-mediated immune responses. Specifically, DM expression may influence susceptibility and resistance to autoimmune diseases. In this study the role of DM in HLA-DR4-restricted presentation of an insulin-dependent diabetes mellitus autoantigen, glutamate decarboxylase (GAD), was tested. Presentation of immunodominant GAD epitope 273-285 was regulated by endogenous DM levels in human B lymphoblasts. T cell responses to exogenous GAD as well as an endogenous cytoplasmic form of this Ag were significantly diminished with increasing cellular expression of DM. Epitope editing by DM was observed only using Ag and not small synthetic peptides, suggesting that this process occurred within endosomes. Results with cytoplasmic GAD also indicated that peptides from this compartment intersect class II proteins in endocytic vesicles where DM editing was facilitated. Changes in DM levels within APC may therefore influence the presentation of autoantigens and the development of autoimmune disorders such as type I diabetes.
 ...
PMID:Editing of an immunodominant epitope of glutamate decarboxylase by HLA-DM. 1284 54


<< Previous 1 2 3 4 5 6 7 8 Next >>