α-Enolase, a Multifunctional Protein: Its Role on Pathophysiological Situations

α-Enolase is a key glycolytic enzyme in the cytoplasm of prokaryotic and eukaryotic cells and is considered a multifunctional protein. α-enolase is expressed on the surface of several cell types, where it acts as a plasminogen receptor, concentrating proteolytic plasmin activity on the cell surface. In addition to glycolytic enzyme and plasminogen receptor functions, α-Enolase appears to have other cellular functions and subcellular localizations that are distinct from its well-established function in glycolysis. Furthermore, differential expression of α-enolase has been related to several pathologies, such as cancer, Alzheimer’s disease, and rheumatoid arthritis, among others. We have identified α-enolase as a plasminogen receptor in several cell types. In particular, we have analyzed its role in myogenesis, as an example of extracellular remodelling process. We have shown that α-enolase is expressed on the cell surface of differentiating myocytes, and that inhibitors of α-enolase/plasminogen binding block myogenic fusion in vitro and skeletal muscle regeneration in mice. α-Enolase could be considered as a marker of pathological stress in a high number of diseases, performing several of its multiple functions, mainly as plasminogen receptor. This paper is focused on the multiple roles of the α-enolase/plasminogen axis, related to several pathologies

Requirement of Plasminogen Binding to Its Cell-Surface Receptor α-Enolase for Efficient Regeneration of Normal and Dystrophic Skeletal Muscle

Adult regenerative myogenesis is central for restoring normal tissue structure and function after muscle damage. In muscle repair after injury, as in severe myopathies, damaged and necrotic fibers are removed by infiltrating inflammatory cells and then replaced by muscle stem cells or satellite cells, which will fuse to form new myofibers. Extracellular proteolysis mediated by uPA-generated plasmin plays a critical role in controlling inflammation and satellite-cell-dependent myogenesis. alpha-enolase has been described as plasminogen receptor in several cell types, where it acts concentrating plasmin proteolytic activity on the cell surface. In this study, we investigated whether alpha-enolase plasminogen receptor plays a regulatory role during the muscular repair process. Inhibitors of alpha-enolase/plasminogen binding: MAb11G1 (a monoclonal antibody against alpha-enolase) and e-aminocaproic acid, EACA (a lysine analogue) inhibited the myogenic abilities of satellite cells-derived myoblasts. Furthermore, knockdown of alpha-enolase decreased myogenic fusion of myoblasts. Injured wild-type mice and dystrophic mdx mice were also treated with MAb11G1 and EACA. These treatments had negative impacts on muscle repair impairing satellite cell functions in vitro in agreement with blunted growth of new myofibers in vivo. Furthermore, both MAb11G1 and EACA treatments impaired adequate inflammatory cell infiltration and promoted extracellular matrix deposition in vivo, which resulted in persistent degeneration. These results demonstrate the novel requirement of alpha-enolase for restoring homeostasis of injured muscle tissue, by controlling the pericellular localization of plasmin activity

Early-onset and classical forms of type 2 diabetes show impaired expression of genes involved in muscle branched-chain amino acids metabolism

The molecular mechanisms responsible for the pathophysiological traits of type 2 diabetes are incompletely understood. Here we have performed transcriptomic analysis in skeletal muscle, and plasma metabolomics from subjects with classical and early-onset forms of type 2 diabetes (T2D). Focused studies were also performed in tissues from ob/ob and db/db mice. We document that T2D, both early and late onset, are characterized by reduced muscle expression of genes involved in branched-chain amino acids (BCAA) metabolism. Weighted Co-expression Networks Analysis provided support to idea that the BCAA genes are relevant in the pathophysiology of type 2 diabetes, and that mitochondrial BCAA management is impaired in skeletal muscle from T2D patients. In diabetic mice model we detected alterations in skeletal muscle proteins involved in BCAA metabolism but not in obese mice. Metabolomic analysis revealed increased levels of branched-chain keto acids (BCKA), and BCAA in plasma of T2D patients, which may result from the disruption of muscle BCAA management. Our data support the view that inhibition of genes involved in BCAA handling in skeletal muscle takes place as part of the pathophysiology of type 2 diabetes, and this occurs both in early-onset and in classical type 2 diabetes

Clustering COVID-19 ARDS patients through the first days of ICU admission. An analysis of the CIBERESUCICOVID Cohort

Background Acute respiratory distress syndrome (ARDS) can be classified into sub-phenotypes according to different inflammatory/clinical status. Prognostic enrichment was achieved by grouping patients into hypoinflammatory or hyperinflammatory sub-phenotypes, even though the time of analysis may change the classification according to treatment response or disease evolution. We aimed to evaluate when patients can be clustered in more than 1 group, and how they may change the clustering of patients using data of baseline or day 3, and the prognosis of patients according to their evolution by changing or not the cluster.Methods Multicenter, observational prospective, and retrospective study of patients admitted due to ARDS related to COVID-19 infection in Spain. Patients were grouped according to a clustering mixed-type data algorithm (k-prototypes) using continuous and categorical readily available variables at baseline and day 3.Results Of 6205 patients, 3743 (60%) were included in the study. According to silhouette analysis, patients were grouped in two clusters. At baseline, 1402 (37%) patients were included in cluster 1 and 2341(63%) in cluster 2. On day 3, 1557(42%) patients were included in cluster 1 and 2086 (57%) in cluster 2. The patients included in cluster 2 were older and more frequently hypertensive and had a higher prevalence of shock, organ dysfunction, inflammatory biomarkers, and worst respiratory indexes at both time points. The 90-day mortality was higher in cluster 2 at both clustering processes (43.8% [n = 1025] versus 27.3% [n = 383] at baseline, and 49% [n = 1023] versus 20.6% [n = 321] on day 3). Four hundred and fifty-eight (33%) patients clustered in the first group were clustered in the second group on day 3. In contrast, 638 (27%) patients clustered in the second group were clustered in the first group on day 3.Conclusions During the first days, patients can be clustered into two groups and the process of clustering patients may change as they continue to evolve. This means that despite a vast majority of patients remaining in the same cluster, a minority reaching 33% of patients analyzed may be re-categorized into different clusters based on their progress. Such changes can significantly impact their prognosis

Paper de la unió del plasminogen a la alfa-enolasa durant la miogènesi "in vitro" i la regeneració muscular "in vivo".

[cat] El sistema d'activació del plasminogen (PA) és un grup de serina-proteases que participen en nombrosos processos en els quals té lloc de degradació de la matriu extracel·lular (ECM). El plasminogen, mitjançant l'acció dels seus activadors específics, dóna lloc a la plasmina activa. La plasmina és una potent proteasa d'ampli espectre de substrat. El seu paper clàssic ha estat la degradació dels coàguls de fibrina, tot i que també actua sobre altres components de l'ECM directament, i de manera indirecta mitjançant l'activació de diverses metal·loproteases. Tanmateix, la plasmina pot activar les formes latents de diversos factors de creixement. Aquest potent sistema de proteases està regulat a diferents nivells: a nivell d'inhibidors i a nivell de receptors que concentren l'activitat proteolítica a l'espai pericel·lular. Existeixen diverses proteïnes situades a la membrana cel·lular que posseeixen l'habilitat d'unir plasminogen, entre elles cal destacar l'alfa-enolasa. L'alfa-enolasa és un enzim glucolític que es transloca a la membrana cel·lular mitjançant un mecanisme desconegut, on actua com a receptor del plasminogen. La unió del plasminogen als seus receptors facilita la seva activació a plasmina i la protegeix de l'acció dels seus inhibidors. El sistema PA participa en un elevat nombre de processos fisiopatològics que requereixen un elevat grau de proteòlisi. Entre aquests processos cal destacar la remodelació tissular i, en particular, la remodelació del múscul esquelètic. El teixit muscular és un bon exemple de proteòlisi extracel·lular massiva després d'un miotraumatisme. Resultats previs demostraren que l'activador del plasminogen de tipus urokinasa (uPA) i el plasminogen desenvolupen un paper fonamental durant el procés de regeneració muscular. El principal objectiu d'aquesta tesi fou l'anàlisi del paper de la unió plasminogen/alfa-enolasa durant la miogènesi in vitro i la regeneració muscular in vivo. Aquest treball es va dur a terme mitjançant l'ús d'inhibidors de la unió plasminogen/alfa-enolasa (MAb 11G1, contra l'alfa-enolasa; i EACA, contra el plasminogen) i l'ús d'un inhibidor de l'activitat proteolítica de la plasmina lliure (aprotinina) en models de miogènesi in vitro i regeneració muscular in vivo. El cultiu de mioblasts murins primaris en presència dels tres inhibidors va demostrar una inhibició sobre la diferenciació de l'ordre d'un 50% després del tractament amb MAb 11G1 i EACA, mentre que l'aprotinina no tingué cap efecte. En canvi, quan s'analitzava el procés de fusió, la inhibició fou del 90%. Aquest resultat indica que, després del bloqueig de la unió del plasminogen al seu receptor, els mioblasts inicien el procés de diferenciació, però no arriben a fusionar-se en cap moment, demostrant que la unió del plasminogen a l'alfa-enolasa és un mecanisme clau durant la miogènesi. A continuació es va analitzar el paper de la unió plasminogen/alfa-enolasa durant la regeneració del múscul esquelètic in vivo, mitjançant l'ús de dos models animals: un model de regeneració muscular mitjançant una injecció amb cardiotoxina (CTX) i el ratolí distròfic mdx, el model animals per a la Distròfia Muscular de Duchenne (DMD). Els resultats obtinguts mostraren que els inhibidors de la unió plasminogen/alfa-enolasa bloquegen el procés de regeneració muscular després d'una lesió amb CTX, mentre que l'aprotinina no té cap efecte, mostrant que l'activitat proteolítica de la plasmina unida a la membrana cel·lular és necessària durant la regeneració muscular. Quan s'analitzà l'efecte dels diferents inhibidors en els ratolins distròfics mdx la patologia esdevingué més severa, indicant que el bloqueig de la unió del plasminogen al seu receptor provoca un important agreujament en la distròfia dels ratolins mdx. Tots aquests resultats demostren que l'activitat proteolítica de la plasmina associada a l'alfa-enolasa desenvolupa un paper fonamental en el procés de regeneració muscular in vivo, mentre que l'activitat proteolítica de la plasmina lliure no participa en aquest procés.[eng] Plasminogen Activation (PA) System is a group of serin-proteases that participates in biological processes in which extracellular matrix (ECM) remodeling takes place. Plasmin, generated by plasminogen activation, is an extracellular protease specialized in the degradation of the ECM components. Several proteins able to bind plasmin(ogen) to the cell surface have been described. In particular, alpha-enolase acts as a plasmin(ogen) receptor in several cell types concentrating proteolytic activity on the cell surface. PA system participates in a high number of biological processes, including skeletal muscle remodelling. Previous results showed an overexpression of alpha-enolase during myoblasts differentiation in vitro, and in skeletal muscle regeneration in vivo, suggesting an important role of this protein during these processes. So, the main goal of this work was the analysis of the role of plasmin(ogen)/alpha-enolase binding during myogenesis and skeletal muscle regeneration. For this goal, we used inhibitors of plasminogen/alpha-enolase binding: MAb 11G1 and EACA. Using primary cultures or Muscle Precursor Cells (MPCs), our results showed that myogenic differentiation, fusion and cell migration were abrograted in the presence of inhibitors of plasmin(ogen)/alpha-enolase binding. The effect of plasmin(ogen)/alpha-enolase binding inhibitors were evaluated in a regeneration model in mice after an injury. Muscle regeneration was blocked by plasmin(ogen)/alpha-enolase binding inhibitors, as assessed by histological and morphological parameters. When the mdx mice (the animal model for Duchenne Muscular Dystrophy, DMD) were treated with plasminogen/alpha-enolase binding inhibitors the myopathology became more severe. Our results demonstrate that plasmin(ogen)/alpha-enolase association is necessary for myogenesis and muscle regeneration to take place correctly

Discovering HIV related information by means of association rules and machine learning

Acquired immunodeficiency syndrome (AIDS) is still one of the main health problems worldwide. It is therefore essential to keep making progress in improving the prognosis and quality of life of affected patients. One way to advance along this pathway is to uncover connections between other disorders associated with HIV/AIDS-so that they can be anticipated and possibly mitigated. We propose to achieve this by using Association Rules (ARs). They allow us to represent the dependencies between a number of diseases and other specific diseases. However, classical techniques systematically generate every AR meeting some minimal conditions on data frequency, hence generating a vast amount of uninteresting ARs, which need to be filtered out. The lack of manually annotated ARs has favored unsupervised filtering, even though they produce limited results. In this paper, we propose a semi-supervised system, able to identify relevant ARs among HIV-related diseases with a minimal amount of annotated training data. Our system has been able to extract a good number of relationships between HIV-related diseases that have been previously detected in the literature but are scattered and are often little known. Furthermore, a number of plausible new relationships have shown up which deserve further investigation by qualified medical experts