Overexpression of lymphotoxin in T cells induces fulminant thymic involution

Activated lymphocytes and lymphoid-tissue inducer cells express lymphotoxins (LTs), which are essential for the organogenesis and maintenance of lymphoreticular microenvironments. Here we describe that T-cell-restricted overexpression of LT induces fulminant thymic involution. This phenotype was prevented by ablation of the LT receptors tumor necrosis factor receptor (TNFR) 1 or LT beta receptor (LTbetaR), representing two non-redundant pathways. Multiple lines of transgenic Ltalphabeta and Ltalpha mice show such a phenotype, which was not observed on overexpression of LTbeta alone. Reciprocal bone marrow transfers between LT-overexpressing and receptor-ablated mice show that involution was not due to a T cell-autonomous defect but was triggered by TNFR1 and LTbetaR signaling to radioresistant stromal cells. Thymic involution was partially prevented by the removal of one allele of LTbetaR but not of TNFR1, establishing a hierarchy in these signaling events. Infection with the lymphocytic choriomeningitis virus triggered a similar thymic pathology in wt, but not in Tnfr1(-/-) mice. These mice displayed elevated TNFalpha in both thymus and plasma, as well as increased LTs on both CD8(+) and CD4(-)CD8(-) thymocytes. These findings suggest that enhanced T cell-derived LT expression helps to control the physiological size of the thymic stroma and accelerates its involution via TNFR1/LTbetaR signaling in pathological conditions and possibly also in normal aging.

Rechtshilfe in Zivilsachen: ausgewählte Auszüge aus der neuen Wegleitung des Bundesamtes für Justiz

Die vorliegenden Beiträge in deutscher und französischer Sprache befassen sich mit Aspekten der Rechtshilfe in internationalen Zivil- und Handelsprozessen. Zur Zustellung von gerichtlichen und aussergerichtlichen Urkunden sowie zur rechtshilfeweisen Beweiserhebung (z. B. Einvernahme mittels Videokonferenz) äussern sich Dr. Alexander Markus sowie Dr. Danielle Gauthey Ladner. Dabei wird insbesondere auf die neue Wegleitung des Bundesamtes für Justiz zu den verschiedenen Haager Übereinkommen eingegangen. Alexander Hilfiker erläutert die Möglichkeiten der Internet-Recherche. Die menschlich vielfach schwierigen Probleme der Kindesentführungen behandeln David Urwyler, Sonja Hauser und Hervé Boéchat. Auf aktuelle Fragen der Anerkennung und Vollstreckung von Zivilurteilen gehen Dr. Samuel Baumgartner und Jean-Marc Wichser ein. Das Thema Vollstreckung von ausländischen Konkurserkenntnissen ist Gegenstand der Beiträge von Prof. Dr. Karl Spühler und von Prof. Dr. Sylvain Marchand.

Plasmodium induces swelling-activated ClC-2 anion channels in the host erythrocyte

Intraerythrocytic growth of the human malaria parasite Plasmodium falciparum depends on delivery of nutrients. Moreover, infection challenges cell volume constancy of the host erythrocyte requiring enhanced activity of cell volume regulatory mechanisms. Patch clamp recording demonstrated inwardly and outwardly rectifying anion channels in infected but not in control erythrocytes. The molecular identity of those channels remained elusive. We show here for one channel type that voltage dependence, cell volume sensitivity, and activation by oxidation are identical to ClC-2. Moreover, Western blots and FACS analysis showed protein and functional ClC-2 expression in human erythrocytes and erythrocytes from wild type (Clcn2(+/+)) but not from Clcn2(-/-) mice. Finally, patch clamp recording revealed activation of volume-sensitive inwardly rectifying channels in Plasmodium berghei-infected Clcn2(+/+) but not Clcn2(-/-) erythrocytes. Erythrocytes from infected mice of both genotypes differed in cell volume and inhibition of ClC-2 by ZnCl(2) (1 mm) induced an increase of cell volume only in parasitized Clcn2(+/+) erythrocytes. Lack of ClC-2 did not inhibit P. berghei development in vivo nor substantially affect the mortality of infected mice. In conclusion, activation of host ClC-2 channels participates in the altered permeability of Plasmodium-infected erythrocytes but is not required for intraerythrocytic parasite survival.