Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Complex protein antigens contain multiple potential T cell recognition epitopes, which are generated through a processing pathway involving partial antigen degradation via proteases, binding to MHC molecules, and display on the APC surface, followed by recognition via the T cell receptor. We have investigated recognition of the GAD65 protein, one of the well-characterized autoantigens in type I diabetes, among individuals carrying the HLA-DR4 haplotypes characteristic of susceptibility to IDDM. Using sets of 20-mer peptides spanning the GAD65 molecule, multiple immunostimulatory epitopes were identified, with diverse class II DR molecules functioning as the restriction element. The majority of T cell responses were restricted by DRB1 molecules; however, DRB4 restricted responses were also observed. Antigen-specific T cell clones and lines were derived from peripheral blood samples of pre-diabetic and IDDM patients and T cell recognition and response were measured. Highly variable proliferative and cytokine release profiles were observed, even among T cells specific for a single GAD65 epitope.
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PMID:Complexity of human immune response profiles for CD4+ T cell epitopes from the diabetes autoantigen GAD65. 1190 49

Human diabetic neuropathy is multifactorial in etiology, with ischemia as a final common pathology. Although impaired vascular endothelial cell function in diabetic microvascular injury is established, the role of thrombomodulin (TM)-dependent protein C antithrombotic mechanism in the pathogenesis of neuropathy is unclear. This neuropathologic case-control study investigated whether vascular endothelial TM expression is deficient in peripheral nerve microvessels in diabetic neuropathy. Sural nerve biopsies from 7 patients with diabetic neuropathy and 10 with axonal neuropathy without vasculopathy were immunostained with anti-TM and anti-von Willebrand factor (vWF; an endothelial cell marker) antibodies. The proportion of TM-positive microvessels was expressed relative to total vWF-staining vessels, according to vessel caliber and regional distribution within the nerve. In diabetic nerves compared with reference controls, the proportion of TM-positive endoneurial microvessels was 15-fold lower (0.02 vs. 0.30 in diabetic nerves vs. controls, P < 0.004), and the proportion of small-caliber epineurial microvessels was 10-fold lower (0.04 vs. 0.43, P < 0.001). No TM expression was detected at the perineurium in diabetic or control nerves. We demonstrate a substantial reduction of vascular endothelial TM expression throughout human diabetic neuropathy. These findings suggest that an impaired native TM-dependent protein C antithrombotic mechanism may contribute to microvascular ischemia in the pathogenesis of diabetic neuropathy.
Diabetes 2002 Jun
PMID:Thrombomodulin deficiency in human diabetic nerve microvasculature. 1203 86

Calciphylaxis is a small vessel vasculopathy involving mural calcification with intimal proliferation, fibrosis, and thrombosis. This syndrome occurs predominantly in individuals with renal failure and results in ischemia and necrosis of skin, subcutaneous fat, visceral organs, and skeletal muscle. The syndrome causes significant morbidity in the form of infection, organ failure, and pain. Mortality rates are high. In individuals with renal failure, risk factors for the development of calciphylaxis include female sex, Caucasian race, obesity, and diabetes mellitus. Many cases occur within the first year of dialysis treatment. Several recent reports demonstrate that prolonged hyperphosphatemia and/or elevated calcium x phosphorus products are associated with the syndrome. Protein malnutrition increases the likelihood of calciphylaxis, as does warfarin use and hypercoagulable states, such as protein C and/or protein S deficiency. Recent advances in diagnostic tools and therapeutic strategies have helped in the management of patients with calciphylaxis.
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PMID:Calciphylaxis: emerging concepts in prevention, diagnosis, and treatment. 1210 Apr 55

A study was carried out on activity of protein C4 in 73 surgical patients (coagulation test, reagents of company PEHAM). The reduction in activity of protein C was observed in patients with focal liver lesion related to disturbance of protein formation function. This percent of disturbances in protein C system is more often found in patients with vascular pathology. This is explained by the mechanism of its action and implication of vascular endothelium into the process. Disturbances in patients with injury infection are stipulated with activity of C and S proteins and availability of mutant factor V--factor Leiden in patients with diabetes. In the first days after surgical intervention the activity of C protein was much reduced. The obtained results emphasize the importance of research in the system of protein C in surgical patients.
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PMID:[Disorders of protein C anticoagulant system in various clinical conditions]. 1251 42

B lymphocytes partially contribute to autoimmune type 1 diabetes (T1D) as a subset of APC with a preferential ability to trigger pathogenic CD4 T cells. We hypothesized that this resulted from the unique ability of B lymphocytes to take up pancreatic beta cell proteins through Ig mediated capture. T1D was significantly delayed, but not prevented, in a NOD stock in which the B lymphocyte Ig repertoire was strongly restricted because of the allelic exclusion induced by transgenic Ig molecules specific for the disease irrelevant hen egg lysozyme (HEL) protein (NOD.IgHEL mice). However, introducing the Ig(mu)null mutation to eliminate the small residual numbers of non-transgenic B lymphocytes in the NOD.IgHEL stock strongly suppressed T1D to the same low levels that characterize B lymphocyte deficient NOD.Ig(mu)null mice. In contrast to standard NOD mice, both the NOD.IgHEL.Ig(mu)null and NOD.Ig(mu)null stocks were unable to generate T cell responses against the candidate diabetes autoantigen, glutamic acid decarboxylase. These results indicate that Ig-mediated capture of beta cell autoantigens accounts for why B lymphocytes have a greater capacity than other APC subtypes to trigger diabetogenic T cells. Hence, defects in B lymphocyte, as well as T lymphocyte, tolerance induction mechanisms may contribute to T1D in NOD mice.
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PMID:The preferential ability of B lymphocytes to act as diabetogenic APC in NOD mice depends on expression of self-antigen-specific immunoglobulin receptors. 1251 57

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.
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PMID:NF-kappa B hyperactivation has differential effects on the APC function of nonobese diabetic mouse macrophages. 1257 41

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.
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PMID:Editing of an immunodominant epitope of glutamate decarboxylase by HLA-DM. 1284 54

Activated protein C (APC) serves as an 'on demand' anticoagulant. Defects in the APC anticoagulant pathway are underlying risk factors for the development of venous and arterial thrombosis. APC has recently been shown to significantly reduce mortality in patients with severe sepsis, presumably by virtue of its ability to down-regulate coagulation as well as inflammation. Our objective was to develop an assay that, for the first time, permits rapid detection of plasma APC. This assay will expedite studies of APC in a variety of vascular disease states including sepsis, severe atherosclerosis, diabetes, and vasculitis. By generating a highly APC-specific monoclonal antibody (HAPC 1555), we have developed an assay that, for the first time, allows rapid detection of plasma APC. The Kd measured for the interaction between APC and HAPC 1555 based on BIAcore studies and binding to immobilized HAPC on microtiter plates is 6.2 +/- 0.9 and 8.8 +/- 1.0 nmol L(-1), respectively. The interaction between HAPC 1555 and APC is Ca2+-dependent, with a Ca2+ concentration of 313 +/- 48 micro mol L(-1) required for half maximal binding. HAPC 1555 interferes with APC-mediated inactivation of factor (F)Va in the presence and absence of phospholipids, suggesting that HAPC 1555 binds to the FVa binding domain of APC. When HAPC 1555 was used in an APC enzyme capture assay, therapeutic APC levels could be measured in 1.5 h, and physiologic levels of APC could be detected between 3 and 19 h. APC levels were also shown to vary markedly in patients with severe sepsis. The rapidity of our APC assay makes APC detection in patients practical clinically. This assay will expedite studies of APC in a variety of vascular disease states including sepsis, severe atherosclerosis, diabetes, and vasculitis.
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PMID:A monoclonal antibody against activated protein C allows rapid detection of activated protein C in plasma and reveals a calcium ion dependent epitope involved in factor Va inactivation. 1499 20

Diabetes mellitus (DM) is associated with enhanced lipid oxidation and persistent platelet activation. We investigated whether oxidant stress (OS) also affects circulating proteins and is associated with an abnormal coagulative pattern. In 72 type 2 DM (T2DM) patients, urinary 8-iso-prostaglandin (PG) F2alpha and 11-dehydro-thromboxane B2 (TXM) were measured as markers of lipid peroxidation and platelet activation, respectively. The carbonyl content of plasma proteins (PCARB) was measured as global index of protein oxidation. 8-Iso-PGF2alpha and PCARB levels were higher in DM patients than in controls (P < 0.05). Likewise, both TXM and prothrombin F1+2 levels were higher in diabetics (P < 0.05). By contrast, anticoagulant markers, such as activated protein C, protein C activation peptide, and soluble thrombomodulin (TM) were depressed in T2DM (P < 0.05). In conclusion, OS in T2DM involves circulating proteins and is associated with an unbalanced promotion of procoagulant reactions. These effects in concert with platelet activation may contribute to atherothrombotic complications in T2DM.
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PMID:Lipid and protein oxidation contribute to a prothrombotic state in patients with type 2 diabetes mellitus. 1287 97

It has been suggested that thrombotic tendency increases the risk of myocardial infarction (MI). To investigate the association between the risk of MI at a young age and genetic thrombogenic disorders (G20210A mutation in the prothrombin gene, G1691A mutation in the factor V gene and deficiencies of protein C, protein S and antithrombin III) we conducted a case-control study among 70 survivors of MI who had experienced the event before the age of 36 and 260 healthy subjects. The G20210A mutation in the prothrombin gene was found more often in young patients with MI than among controls (11.4 versus 3.1%). The odds ratio (OR) for MI for carriers versus non-carriers was 4 (95% confidence interval [CI], 1.5 to 11.3). The adjusted OR for major cardiovascular risk factors (smoking, hypecholesterolaemia, diabetes mellitus, hypertension and obesity) was 4.3 (95% CI, 1.3 to 14). The simultaneous presence of both G20210A mutation in the prothrombin gene and smoking further increased the risk of MI compared with nonsmokers and non-carriers (OR, 58; 95% CI, 11.4-294). The G1691A mutation in factor V gene was not associated with an increased relative risk for MI (OR, 0.87; 95% CI, 0.26 to 2.5). Finally, there was no significant difference in the prevalence of deficiencies of protein C, protein S and antithrombin III between cases and controls. In conclusion, our data indicate that the G20210A mutation in the prothrombin gene was the only genetic prothrombotic risk factor associated with the risk of developing MI under the age of 36 years.
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PMID:Myocardial infarction under the age of 36: prevalence of thrombophilic disorders. 1573 21


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