Thomas Geiler

Etiopathogenesis of Systemic Lupus Erythematosus

Systemic lupus erythematosus is an autoimmune disease of unknown etiology. Research efforts of the last few years have mainly focused on basic molecular and cellular pathogenetic processes of the disease. Consequently, this paper reviews the etiopathogenetic hallmarks, such as impaired amount and presentation of nuclear antigens, production of antinuclear antibodies by T-cell-dependent B cell stimulation and organ damage by anti-dsDNA antibodies or immune complexes that are discussed at the present time. In summary, the hypothesis of a dysregulation of apoptotic cell clearance is strongly supported and broadly discussed.

Chlorpromazine induces apoptosis in activated human lymphoblasts: a mechanism supporting the induction of drug-induced lupus erythematosus?

OBJECTIVE Drug-induced lupus erythematosus is a serious side effect of certain medications, such as procainamide, quinidine, hydralazine, chlorpromazine, and isoniazid, the underlying pathogenesis of which is unresolved. In this study, we examined the influence of these drugs on the regulation of apoptosis, or programmed cell death, in quiescent and activated human lymphocytes. We also discuss the dysregulation of apoptosis as a pathogenetic factor in systemic lupus erythematosus. METHODS Peripheral blood mononuclear cells or activated lymphoblasts from normal donors were incubated with different concentrations of each of the above-mentioned drugs. RESULTS We did not find induction of apoptosis in quiescent cells over a broad concentration range. In contrast, lymphoblasts readily underwent apoptosis when cultured with chlorpromazine, but not any of the other drugs, after stimulation with interleukin-2 (IL-2) in a dose-, time- and cell cycle-dependent manner. By several lines of evidence, toxicity was ruled out. Characteristic features of apoptosis-like incorporation of propidium iodide (PI), such as increased annexin V binding, changes in mitochondrial membrane potential, and induction of DNA breaks (as evidenced by TUNEL techniques), could be induced in lymphoblasts after chlorpromazine treatment. Chlorpromazine did not cause apoptosis by inhibition of cytokine binding or blockade of early intracellular signaling. The protease inhibitor Z-VAD and the ceramide inhibitor sphingosine 1-phosphate effectively blocked chlorpromazine-induced apoptosis (by PI staining and by externalization of phosphatidylserine), in contrast to the caspase 3/CPP32 inhibitor DEVD, which had only minor effects. Western blot analysis revealed IL-2-mediated phosphorylation of extracellular signal-regulated kinase, which was sensitive to chlorpromazine. Using lymphoblasts from a patient with Canale-Smith syndrome, we found that chlorpromazine-mediated apoptosis is Fas/ APO-1 independent. CONCLUSION These data suggest that chlorpromazine mediates apoptosis in human lymphoblasts through specific activation of intracellular proapoptotic signaling cascades. This mechanism might lead to an unsynchronized inflow of apoptotic break-down products and thereby to the induction of (auto)immunity against nuclear components.

CD45 Tyrosine Phosphatase Controls Common γ-Chain Cytokine-Mediated STAT and Extracellular Signal-Related Kinase Phosphorylation in Activated Human Lymphoblasts: Inhibition of Proliferation Without Induction of Apoptosis

The objective of this study was to test whether CD45 signals can influence signaling processes in activated human lymphoblasts. To this end, we generated lymphoblasts which proliferate in response to common γ-chain cytokines, but readily undergo apoptosis after cytokine withdrawal. In experiments with the CD45R0 mAb UCHL-1, but not control CD45 mAbs, we found significant inhibition of proliferation. Interestingly, the pan-CD45 mAb GAP8.3, which is most effective in inhibition of OKT-3-mediated proliferation in quiescent lymphocytes, was ineffective in lymphoblasts. Addition of CD3 mAb OKT-3 had no influence on IL-2-mediated proliferation (with or without UCHL-1). In contrast, after addition of OKT-3 to IL-4- and IL-7-stimulated proliferation assays, UCHL-1 signals could not significantly alter cellular proliferation. We did not find induction of apoptosis following CD45R0 signaling. In Western blots using mAbs detecting phosphorylated STAT-3, STAT-5, STAT-6, or extracellular signal-related kinase 1/2, we found that CD45R0 signaling could effectively diminish phosphorylation of these intracellular signaling components. Using RT-PCR, we found that CD45R0 signaling inhibited IL-2 mRNA production without major influence on IL-13, IL-5, or IFN-γ mRNA levels. Costimulation with OKT-3 and IL-2 optimally induced secretion of IFN-γ, TNF-α, and IL-5, which was not decreased by CD45 signals. In conclusion, we illustrate that CD45R0 signals control early cytokine receptor-associated signaling processes and mRNA and DNA synthesis in activated human lymphoblasts. Furthermore, we show the existence of CD45 epitopes (GAP8.3), which are active and critical for signaling in quiescent lymphocytes, but are nonfunctional in activated human lymphoblasts.

Myokardiale Beteiligung des Eosinophilie-Syndroms bei einer Fadenwurminfektion Nachweis regionaler Myokardrestriktion mittels Pulswellen-Gewebe-Doppler-Echokardiographie

CASE REPORT The case of a 57-year-old woman is reported who was admitted for peripheral hypereosinophilia. DIAGNOSIS Detailed investigations revealed first of all a hypereosinophilic syndrome with infiltration of bone marrow and lung. The patient suffered more and more from angina pectoris with signs of heart failure. Coronary angiography was therefore carried out which showed normal coronary arteries. With suspicion of myocardial involvement endomyocardial biopsies were performed which revealed the presence of Löfflers endocarditis parietalis fibroplastica. Finally, serological studies for parasites disclosed a positive ELISA test for Toxocara, confirmed later to be rising. CONCLUSION Myocardial involvement of hypereosinophilia, caused by Toxocara is not described until now. Further diagnostic by means of pulsed wave tissue Doppler echocardiography provided regional differentiation of a restrictive filling pattern which documented the importance of this new diagnostic tool in myocardial illness.ZusammenfassungFallbericht: Wir berichten über eine 57jährige Patientin, die zur Abklärung vermehrter eosinophiler Granulozyten aufgenommen worden war. Diagnostik: Die ausführliche Diagnostik ergab zunächst ein Eosinophilie-Syndrom mit Infiltrationen in das Knochenmark und in die Lunge. Klinisch imponierten zunehmend pektanginöse Beschwerden mit Zeichen einer Myokardinsuffizienz. Die daraufhin durchgeführte invasive Diagnostik ergab einen unauffälligen Koronarstatus. Deshalb wurden unter dem Verdacht einer myokardialen Beteiligung Endomyokardbiopsien entnommen, die histologisch das Bild einer Endokarditis parietalis fibroplastica Löffler ergaben. Serologische Untersuchungen nach Parasiten erbrachten schließlich im ELISA-Test positive Titer für eine Fadenwurminfektion durch Toxocara, die im Verlauf noch anstiegen. Die weiterführende Diagnostik mittels Pulswellen-Gewebe-Doppler-Echokardiographie verifizierte die myokardiale Beteiligung im Sinne einer restriktiven Füllungsstörung. Schlußfolgerung: Eine myokardiale Beteiligung durch Eosinophilie, hervorgerufen durch Toxocara, wurde bisher nicht beschrieben. Die Diagnostik mittels Pulswellen-Gewebe-Doppler-Echokardiographie erlaubt die regionale Differenzierung restriktiver Füllungsstörungen, wodurch die Bedeutung dieser neuen diagnostischen Möglichkeit bei myokardialen Erkrankungen dokumentiert werden konnte.AbstractCase Report: The case of a 57-year-old woman is reported who was admitted for peripheral hypereosinophilia. Diagnosis: Detailed investigations revealed first of all a hypereosinophilic syndrome with infiltration of bone marrow and lung. The patient suffered more and more from angina pectoris with signs of heart failure. Coronary angiography was therefore carried out which showed normal coronary arteries. With suspicion of myocardial involvement endomyocardial biopsies were performed which revealed the presence of Löfflers endocarditis parietalis fibroplastica. Finally, serological studies for parasites disclosed a positive ELISA test for Toxocara, confirmed later to be rising. Conclusion: Myocardial involvement of hypereosinophilia, caused by Toxocara is not described until now. Further diagnostic by means of pulsed wave tissue Doppler echocardiography provided regional differentiation of a restrictive filling pattern which documented the importance of this new diagnostic tool in myocardial illness.

Pathogenese der rheumatoiden Arthritis

Zusammenfassung□ HintergrundTrotz des Einsatzes moderner molekularer Untersuchungsmethoden ist die Pathogenese von Autoimmunerkrankungen wie der rheumatoiden Arthritis nach wie vor nicht komplett verstanden.□ HypothesenIn der vorliegenden Übersichtsarbeit werden die zwei favorisierten Hypothesen zur Pathogenese der rheumatoiden Arthritis vorgestellt und verglichen. Hypothese 1 stellt T-Lymphozyten und T-Lymphozyten-abhängige Phänomene in das Zentrum des pathogenetischen Geschehens. In Hypothese 2 hingegen wird die Rolle alterierter synovialer Fibroblasten und ihrer spezifischen Eigenschaften als kritisch für die Zerstörung entzündetr Gelenke betont. Beide Hypothesen werden sorgfältig diskutiert und Ausblicke für zukünftige Forschungsschwerpunkte gegeben.□ SchlußfolgerungEinblicke in die Pathogenese der RA eröffnen Möglichkeiten, neue, auf die Inhibierung pathogenetisch relevanter Prozesse gerichtete Therapieprinzipien zu entwickeln.Summary□ BackgroundDespite ongoing intensive research using sophisticated new molecular tools and methods, the pathogenesis of autoimmune diseases such as rheumatoid arthritis (RA) is still not completely understood.□ HypothesesIn this paper the two favorite hypotheses of the pathogenesis of theumatoid arthritis currently discussed are introduced and compared. Hypothesis 1 is focussing on the central role of the T cells and T cell dependent phenomena in the pathogenetic scenario of RA. In contrast, hypothesis 2 stresses the role of altered synovial fibroblasts and their specific features critical for the destruction of inflamed joints. Both hypotheses are thoroughly discussed and suggestions for further research activities are made.□ ConclusionInsights in the pathogenesis of RA provide options to develop new therapeutic strategies aimed at the inhibition of pathogenetic relevant processes.

Gentherapie der rheumatoiden Arthritis – ein bereits anwendbares Therapieprinzip?

Zusammenfassung Mit einem zunehmenden Kentnisstand über pathogenetische Mechanismen, die bei der rheumatoiden Arthritis zu einer Gelenkdestruktion führen, haben sich neue Therapieprinzipien entwickeln lassen, die durch eine Blockade von proinflammatorischen Zytokinen oder der Anwendung von antiinflammatorischen Zytokinen den Krankheitsverlauf zum Teil außerordentlich günstig beeinflussen. Mit den zusätzlichen Möglichkeiten, Gene für antiinflammatorische Therapieprinzipien wie den Interleukin 1 Rezeptorantagonisten in Zellen einzubringen, sind auch erste Versuche, basierend auf vorangegangenen Experimenten im Versuchstier, bei Patienten mit einer RA vorgenommen worden, mit dem Ziel die Krankheitsaktivität durch die intraartikuläre Injektion von transduzierten autologen Zellen zu behandeln. Die ersten Versuche sind ermutigend, doch ist es zu früh, dieses Therapieprinzip als eine Behandlungsmethode für die rheumatoide Arthritis anzubieten. Weitere Untersuchungen, nicht zuletzt hinsichtlich der Bereitstellung besserer Vektoren sind notwendig, um eine Gentherapie der rheumatoiden Arthritis zu realisieren. Summary Based upon our increasing knowledge of mechanisms underlying tissue destruction in RA patients, new therapeutic principles have been developed, aimed at blocking proinflammatory cytokines or using antiinflammatory cytokines. Both principles, however, have proven to be very effective. In addition, the availability of the methodology to transduce cells with genes has initiated first experiments in animal models to test whether gene therapy for arthritis is suitable, followed by a first, very carefully formulated protocol for human RA. Gene therapy for RA has to still be considered as an experimental form of therapy in a very early stage, not allowing even now any serious treatment offer to RA patients. Several problems, such as the question of a suitable vector system have not yet been solved. With more experiments this therapeutic principle might become available and might prove effective even in a disease with a systemic character like RA in the coming years.