Celiac disease patient IgA antibodies induce endothelial adhesion and cell polarization defects via extracellular transglutaminase 2

We have recently found that celiac disease patient serum-derived autoantibodies targeted against transglutaminase 2 interfere with several steps of angiogenesis, including endothelial sprouting and migration, though the mechanism involved remained to be fully characterized. This study now investigated the processes underlying the antiangiogenic effects exerted by celiac disease patient antibodies on endothelial cells, with particular regard to the adhesion, migration, and polarization signaling pathway. We observed that celiac IgA reduced endothelial cell numbers by affecting adhesion without increasing apoptosis. Endothelial cells in the presence of celiac IgA showed weak attachment, a high susceptibility to detach from fibronectin, and a disorganized extracellular matrix due to a reduction of protein cross-links. Furthermore, celiac patient IgA led to secretion of active transglutaminase 2 from endothelial cells into the culture supernatants. Additionally, cell surface transglutaminase 2 mediated integrin clustering in the presence of celiac IgA was coupled to augmented expression of β1-integrin. We also observed that celiac patient IgA-treated endothelial cells had migratory defects and a less polarized phenotype when compared to control groups, and this was associated with the RhoA signaling pathway. These biological effects mediated by celiac IgA on endothelial cells were partially influenced but not completely abolished by R281, an irreversible extracellular transglutaminase 2 enzymatic activity inhibitor. Taken together, our results imply that celiac patient IgA antibodies disturb the extracellular protein cross-linking function of transglutaminase 2, thus altering cell-extracellular matrix interactions and thereby affecting endothelial cell adhesion, polarization, and motility.     

Anti-type 2 transglutaminase antibodies as modulators of type 2 transglutaminase functions: a possible pathological role in celiac disease

Auto-antibodies to the ubiquitous enzyme type-2 transglutaminase (TG2) are a specific hallmark of celiac disease (CD), a widely diffused, multi-factorial disease, affecting genetically predisposed subjects. In CD an inflammatory response, at the intestinal level, is triggered by diet consumption of gluten-containing cereals. Intestinal mucosa displays various degrees of atrophy and hyperplasia, with consequent global intestinal dysfunction and other relevant extra-intestinal symptoms. Through deamidation of specific glutamines of gluten-derived gliadin peptides, TG2 strongly enhances gliadin immunogenicity. In addition, TG2 cross-linking activity may generate complexes between TG2 itself and gliadin peptides, and these complexes seem to cause the auto-immune response by means of an apten-carrier-like mechanism of antigen presentation. Anti-TG2 antibodies can be early detected in the intestinal mucosa of celiac patients and are also abundantly present into the serum, thus potentially reaching other organs and tissues by blood circulation. Recently, the possible pathogenetic role of auto-antibodies to TG2 in CD has been investigated. Here, we report an overview about the genesis of these antibodies, their specificity, their modulating ability toward TG2 enzymatic or non-enzymatic activities and their biological effects exerted by interacting with extracellular TG2 or with cell-surface TG2. We also discuss the auto-immune response occurring in CD against other TG members (i.e. type 3 and type 6) and analyze the occurrence of anti-TG2 antibodies in other auto-immune CD-related diseases. Data now available let us to suppose that, even if antibodies to TG2 do not represent the triggering molecules in CD, they could be important players in disease progression and manifestations.     

Continuous quantitative recording of changes in vascular permeability

Zusammenfassung Es wird die Anwendung radioaktiven Phosphanilsäure-Rinderserum-Albumins zur kontinuierlichen Messung von Änderungen der Gefässwandpermeabilität beschrieben.

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This work was supported by a grant and Fellowship (to A.B.) from the Asthma Foundation of New South Wales and a grant from the United States Public Health Service (Grant No. HE 08513-02).     

Increased vascular permeability in the primary cutaneous allograft response in the rat

Résumé La réaction cutanée de l'immunité de transplantation contre une greffe allogénique est accompagnée d'une forte mais courte augmentation de la perméabilité vasculaire. La réponse vasculaire apparait rapidement et cela avant les effets macroscopique ou histologiques de l'immunité de transplantation.     

Changes in vascular permeability and dermal mucopolysaccharides in the female rat after parathyroidectomy

Riassunto Nei ratti femmine paratiroidectomizzati si osserva un aumento della permeabilità vasale ed una modificazione della colorazione metacromatica del derma, indipendenti dalla concentrazione del calcio nel sangue. Tali variazioni vengono attribuite a modificazioni strutturali dei mucopolisaccaridi della sostanza fondamentale del connettivo.     

Increased vascular permeability induced in synovialis of the rat by histamine,serotonin and bradykinin

Résumé La perméabilité vasculaire de la membrane synoviale du rat est augmentée par l'histamine, la sérotonine et la bradykinine. Dans cette réaction la sérotonine est plus active que l'histamine et la bradykinine.

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L.P.B. is supported by a Medical Postgraduate Research Scholarship from the National Health and Medical Research Council of Australia.

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We are indebted to Associate ProfessorJ. Garcia-Lémé, University of São Paulo, Brazil, for advice.     

Kinetics of increased vascular permeability induced in rat skin by serotonin

Résumé Les auteurs ont étudié la cinétique du passage des complexes protein-colorant à travers les capillaires cutanés dont la perméabilité a été augmentée par l'injection préalable de serotonin dans la peau. Les résultats obtenus ont permis d'établir les lois qui règlent cette cinétique et le rôle des recepteurs adrénergic dans le phenomen inflammatoire.     

Properties of vascular permeability factor in human sera for guinea-pig skin

Summary Properties of vascular permeability factor in native human sera (PF/Nat) showed close similarities with those of necrotizing factor. Time course studies revealed that skin necrosis could be initiated by enhanced vascular permeability.Acknowledgment. The authors wish to thank Prof. H. Hayashi, Kumamoto University for encouragement and discussions.     

Effect of retinoic acid on liver transglutaminase activity and carbon tetrachloride-induced liver damage in mice

Transglutaminase (TGase) activity in the cytosol fraction of the mouse liver increased following intraperitoneal injection of retinoic acid. Retinoic acid inhibited the carbon tetrachloride-induced increase in serum alanine transaminase activity. These findings suggest that TGase is involved in the effect of retinoic acid on carbon tetrachloride-induced liver damage.     

On the effect of insulin on lactate permeability through the nuclear membrane

Résumé L'addition d'insuline aux noyaux isolés du thymus de rat peut prévenir les pertes de lactate endogène se produisant à travers de la membrane nucléaire.

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The authors wish to thank Prof. F. J.Loomeijer and Dr. H. M.Klouwen for the stimulating discussions during the work.     

Effect of retinoic acid on liver transglutaminase activity and carbon tetrachloride-induced liver damage in mice.

Transglutaminase (TGase) activity in the cytosol fraction of the mouse liver increased following intraperitoneal injection of retinoic acid. Retinoic acid inhibited the carbon tetrachloride-induced increase in serum alanine transaminase activity. These findings suggest that TGase is involved in the effect of retinoic acid on carbon tetrachloride-induced liver damage.     

Properties of vascular permeability factor in human sera for guinea-pig skin.

Properties of vascular permeability factor in native human sera (PF/Nat) showed close similarities with those of necrotizing factor. Time course studies revealed that skin necrosis could be initiated by enhanced vascular permeability.     

Effect of sodium on passive permeability of non-electrolytes through the intestinal wall

Zusammenfassung Der Einfluss des Natriums auf die passive Permeabilität der Jejunum-Schleimhaut der Laboratoriumsratte gegenüber wasserlöslichen, nichtmetabolisierbaren und elektroneutralen Substanzen (Thioharnstoff, Azetamid) wurde untersucht. Wird das Natrium des NaCl in der Perfusionsflüssigkeit durch Trisoder Cholin-Kationen ersetzt, so nehmen sowohl der transepitheliale Glukosetransport wie auch die Mobilität der geprüften Substanzen ab.

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This work has been supported by a research grant of the Consiglio Nazionale delle Ricerche, Roma. The authors acknowledge, with warm appreciation, the valuable technical assistance of Mr. R.Parotelli.     

Mechanical forces in lymphatic vascular development and disease

The lymphatic vasculature is essential for fluid homeostasis and transport of immune cells, inflammatory molecules, and dietary lipids. It is composed of a hierarchical network of blind-ended lymphatic capillaries and collecting lymphatic vessels, both lined by lymphatic endothelial cells (LECs). The low hydrostatic pressure in lymphatic capillaries, their loose intercellular junctions, and attachment to the surrounding extracellular matrix (ECM) permit passage of extravasated blood plasma from the interstitium into the lumen of the lymphatic capillaries. It is generally thought that interstitial fluid accumulation leads to a swelling of the ECM, to which the LECs of lymphatic capillaries adhere, for example via anchoring filaments. As a result, LECs are pulled away from the vascular lumen, the junctions open, and fluid enters the lymphatic vasculature. The collecting lymphatic vessels then gather the plasma fluid from the capillaries and carry it through the lymph nodes to the blood circulation. The collecting vessels contain intraluminal bicuspid valves that prevent fluid backflow, and are embraced by smooth muscle cells that contribute to fluid transport. Although the lymphatic vessels are regular subject to mechanical strain, our knowledge of its influence on lymphatic development and pathologies is scarce. Here, we discuss the mechanical forces and molecular mechanisms regulating lymphatic vascular growth and maturation in the developing mouse embryo. We also consider how the lymphatic vasculature might be affected by similar mechanomechanisms in two pathological processes, namely cancer cell dissemination and secondary lymphedema.     

Carbon tetrachloride modulates the rat hepatic microsomal UDP-glucuronyl transferase activity and membrane fluidity

Summary Modulations in rat hepatic microsomal UDP-glucuronyl transferase activity have been observed during carbon tetrachloride (CCl₄) poisoning, with a large decrease in the enzyme cooperativity and increase in the membrane fluidity, occurring 30 min after administration. The results strengthen the possibility that an increase in microsomal membrane fluidity may be an early key event in liver injury induced by CCl₄.Acknowledgments. This work was supported by funds of the University of Athens.