RESUMEN
Non-enzymatic modification of proteins by carbohydrates, known as glycation, leads to generation of advanced glycation end-products (AGEs). In our study we used in vitro generated AGEs to model glycation in vivo. We discovered in vivo analogs of unusual melibiose-adducts designated MAGEs (mel-derived AGEs) synthesized in vitro under anhydrous conditions with bovine serum albumin and myoglobin. Using nuclear magnetic resonance spectroscopy we have identified MAGEs as a set of isomers, with open-chain and cyclic structures, of the fructosamine moiety. We generated a mouse anti-MAGE monoclonal antibody and show for the first time that the native and previously undescribed analogous glycation product exists in living organisms and is naturally present in tissues of both invertebrates and vertebrates, including humans. We also report MAGE cross-reactive auto-antibodies in patients with diabetes. We anticipate our approach for modeling glycation in vivo will be a foundational methodology in cell biology. Further studies relevant to the discovery of MAGE may contribute to clarifying disease mechanisms and to the development of novel therapeutic options for diabetic complications, neuropathology, and cancer.
Asunto(s)
Diabetes Mellitus/inmunología , Carbohidratos de la Dieta/inmunología , Epítopos/inmunología , Productos Finales de Glicación Avanzada/inmunología , Melibiosa/inmunología , Animales , Autoanticuerpos/sangre , Autoanticuerpos/inmunología , Reacciones Cruzadas , Diabetes Mellitus/sangre , Diabetes Mellitus/metabolismo , Carbohidratos de la Dieta/metabolismo , Productos Finales de Glicación Avanzada/metabolismo , Glicosilación , Humanos , Melibiosa/metabolismo , RatonesRESUMEN
The problems concerning the pathogenicity and virulence of some bacteria of the Enterobacteriaceae family are described. The structure and functional variety of the outer membrane proteins on the cell surface are presented as potent immunogens based on the structure of the cell envelope. These proteins participate in stabilization of the membrane structure and adhesion to other cells,are receptors for bacteriophages, and play a key role in signal transduction, intracellular transport, and energy transformation processes ensuring proper cell functioning. Moreover, these proteins have a protective function against immune reactions of the infected organism. Referring to current literature data, the authors' own results are reviewed on the methodology of isolating outer membrane proteins and their participation in pathogenicity with regard to molecular mimicry. The isolated and characterized 45-kDa enolase-like protein expressing similarity to human enolase should not be a component of vaccine, although it is considered a diagnostic marker of tissue damage. Presented are also results of studies on the role of the outer membrane protein OMP38, recognized by the human immune system as an important factor in antibacterial immunity. OMP38 is considered an antigen and carrier in conjugate vaccines, but also a specific diagnostic marker of immune deficiencies useful in monitoring the level of immunity against bacteria of the Enterobacteriaceae family.
Asunto(s)
Enterobacteriaceae/inmunología , Enterobacteriaceae/patogenicidad , Inmunidad , Transducción de Señal , Adhesión Celular , Regulación Bacteriana de la Expresión Génica , Humanos , VirulenciaRESUMEN
The receptor for advanced glycation end products (RAGE) is a multiligand cell-surface protein and belongs to the immunoglobulin superfamily. RAGE is expressed by different cell types, including macrophages, lymphocytes, endothelial, neuronal, and smooth muscle cells. In addition to advanced glycation end products (AGEs), RAGE binds amphoterin, S100/calgranulin, amyloid, transthyretin, and a leukocyte integrin, Mac-1. Engagement of RAGE in intracellular signaling leads to the activation of the proinflammatory transcription factor NF-kappaB to sustained cellular dysfunction and tissue destruction. In this study a pivotal role of RAGE in the progression of various diseases, i.e. diabetes, inflammation, neurodegeneration, tumors, vascular injury, atherosclerosis, and septic shock, is presented.
Asunto(s)
Productos Finales de Glicación Avanzada/metabolismo , Receptores Inmunológicos/metabolismo , Animales , Aterosclerosis/metabolismo , Proteínas de Unión al ADN/metabolismo , Diabetes Mellitus/metabolismo , Progresión de la Enfermedad , Humanos , Inflamación/metabolismo , Neoplasias/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Receptor para Productos Finales de Glicación Avanzada , Choque Séptico/metabolismo , Ubiquitina-Proteína Ligasas , Enfermedades Vasculares/metabolismoRESUMEN
Defensins and cathelicidins belong to antimicrobial peptides (AMP), called also the natural antibiotics. They are found in Prokaryotes and Eukaryotes, also are synthesized in plants. These molecules were described in bacteria, invertebrates, vertebrates, also in mammals including humans. The amino-acids sequence is determined for about 880 antimicrobial peptides, and their classification is difficult and complex. These oligo- and polypeptides, are killing the microbes or inhibit their growth, are bactericidal to Gram-negative, Gram-positive bacteria, neutralizing toxins, demonstrated antiviral activity. AMP are multifunctional molecules, playing the first line of defense in human organism as effectors of unspecific immunity, with a broad spectrum of activity against pathogens, are characterized by controlling the physiological bacterial flora, often acting synergistically, are produced in different cells as defense against mechanisms of microbial resistance. They are chemotactic to neutrophiles and T cells, activate the dendritic cells. In human organism defensins are expressed in several cells and tissues, in neutrophiles, platelets, epithelial cells, in liver, skin, eye conjunctiva. Deficiency of defensins or cathelicidins cause pathological symptoms in atopic allergies or in Kostman disease. Several synthetic peptides are currently at the final phases of clinical trials regarding treatment of various bacterial infections. Defensins or cathelicidins could be also efficient as adjuvants or carriers for vaccines, in dairy industry as preservatives. This work presents some problems concerning the occurrence of AMP, especially defensins and cathelicidins of mammals, their classification, structure, various functions and mechanisms of bactericidal activity, and also their use in treatment of some infectious diseases.