Effects of theophylline on ADCY5 activation-From cellular studies to improved therapeutic options for ADCY5-related dyskinesia patients.

We show the effects of the three purine derivatives, caffeine, theophylline, and istradefylline, on cAMP production by adenylyl cyclase 5 (ADCY5)-overexpressing cell lines. A comparison of cAMP levels was performed for ADCY5 wild-type and R418W mutant cells. ADCY5-catalyzed cAMP production was reduced with all three purine derivatives, while the most pronounced effects on cAMP reduction were observed for ADCY5 R418W mutant cells. The gain-of-function ADCY5 R418W mutant is characterized by an increased catalytic activity resulting in elevated cAMP levels that cause kinetic disorders or dyskinesia in patients. Based on our findings in ADCY5 cells, a slow-release formulation of theophylline was administered to a preschool-aged patient with ADCY5-related dyskinesia. A striking improvement of symptoms was observed, outperforming the effects of caffeine that had previously been administered to the same patient. We suggest considering theophylline as an alternative therapeutic option to treat ADCY5-related dyskinesia in patients.

Platelet transfusion alters CD40L blood level and release capacity in patients suffering from thrombocytopenia.

BACKGROUND: Platelet (PLT)-derived cytokines, such as soluble CD40 ligand (sCD40L), play an important role in the development of adverse transfusion reactions associated with the administration of PLT products. In this study, we determined sCD40L concentration and release capacity in patients with thrombocytopenia before and after receiving a PLT transfusion. STUDY DESIGN AND METHODS: The study included 12 patients suffering from chemotherapy-induced thrombocytopenia. sCD40L levels and release capacity were measured in plasma samples of the patients before and after PLT administration as well as in the respective plateletpheresis concentrates by enzyme-linked immunosorbent assay. Sixteen healthy blood donors served as a control group. RESULTS: In PLT concentrates, elevated sCD40L levels (2567±134 pg/mL) were observed in comparison to plasma sCD40L levels in controls (238.4±35.3 pg/mL). sCD40L plasma concentration of patients with thrombocytopenia was significantly reduced (86.3±16.7 pg/mL) before transfusion and increased to nearly normal levels (204.4±24.8 pg/mL) after PLT administration. In parallel, the sCD40L release capacity per PLT showed no significant difference between controls and patients with thrombocytopenia before transfusion (33.3±2.6 and 29.3±4.6 ag/PLT, respectively) but was significantly reduced after PLT transfusion (22.4±2.7 compared to 29.3±4.6 ag/PLT). CONCLUSIONS: In patients with thrombocytopenia, sCD40L levels were clearly influenced by PLT transfusions: PLT administration led to a normalization of sCD40L plasma concentration. Nevertheless, adverse transfusion reactions did not occur in these patients. The sCD40L release capacity was enhanced by PLT administration dependent on the increase in the amount of PLT count.

Comparison of soluble CD40L concentrations and release capacities in apheresis and prestorage pooled platelet concentrates.

INTRODUCTION: Soluble CD40L (sCD40L) is expressed by platelets and is involved in the stabilization of arterial thrombi. Additionally, it was shown that sCD40L accumulation occurred in stored blood products triggering adverse transfusion reactions like TRALI. To study the influence of the preparation technique on sCD40L accumulation and platelet function we examined CD40L concentrations in prestorage pooled platelet concentrates compared to apheresis products. In addition, sCD40L release capacity was determined as a marker for platelet viability. MATERIAL AND METHODS: sCD40L concentrations were determined in prestorage pooled platelet concentrates (n = 8) and in platelet apheresis concentrates (n = 8) before and after platelet stimulation (recalcification and clot formation) at day 1, 3 and 5 under routine storage conditions. sCD40L concentrations were determined by a commercially available ELISA kit. RESULTS: sCD40L concentrations in storage medium increased over time in prestorage pooled platelet concentrates (from 1,185 pg/mL ± 87 pg/mL at day 1 to 4,464 pg/mL ± 212 pg/mL at day 5) as well as in apheresis products (from 581 pg/mL ± 124 pg/mL at day 1 to 2,718 pg/mL ± 154 pg/mL at day 5) in a hyperbolic manner. Recalcification and clot formation caused an increase in sCD40L concentrations (for example 3,842 pg/mL ± 769 pg/mL before platelet activation to 31,219 pg/mL ± 2,063 pg/mL after platelet activation at day 3), and we observed comparable release capacities for both preparation techniques, however, decreasing over storage time up to 50% (day 5) of the respective control value (day 1). CONCLUSIONS: Amounts of sCD40L accumulation and release capacity during storage of platelet concentrates were dependent on storage duration, but showed no relevant differences regarding the preparation technique. After 5 days of storage, CD40L basal levels were increased, in contrast sCD40L release capacity was decreased. By recalcification and clot formation sCD40L release capacity could be easily induced and is assumed to be used as a marker for platelet viability.