Safety and tolerability of a modified filter-type device for leukocytapheresis using ACD-A as anticoagulant in patients with mild to moderately active ulcerative colitis. Results of a pilot study.

Cellsorba™ is a medical device for leukocytapheresis (LCAP) treatment of ulcerative colitis (UC). Cellsorba™ EX Global type has been developed from Cellsorba E for intended use with ACD-A as anticoagulant. We evaluated safety and efficacy of the modified Cellsorba using ACD-A in a pilot trial comprising patients with active UC, despite receiving 5-ASA. A total of 10 LCAP treatments/patients were administered. Safety assessment focused on clinical signs and symptoms, hematological variables, as well as levels of bradykinin and IL-6. Efficacy was determined using the Mayo clinical/endoscopic scoring index as well histological assessment of biopsies. Additional aim was to evaluate the impact of apheresis system lines and filter on selected regulatory molecules. All six subjects completed the trial without any serious adverse events. WBC, platelet counts, and levels of bradykinin and IL-6 were not significantly affected. The median Mayo score decreased from 8.0 to 3.5 at week 8 (and to 2 at week 16 for the responders). Four patients were responders, of whom two patients went into remission. Median histological scores decreased from 3.5 to 2.0 in these four patients. Concentration of LL-37 increased within the apheresis system lines. LCAP with Cellsorba EX using ACD-A as anticoagulant was found to be a safe and well-tolerated procedure in patients with active UC. The positive impact on efficacy parameters merits further evaluation in a controlled fashion.

Synapsin I is phosphorylated at Ser603 by p21-activated kinases (PAKs) in vitro and in PC12 cells stimulated with bradykinin.

The function of synapsin I is regulated by phosphorylation of the molecule at multiple sites; among them, the Ser(603) residue (site 3) is considered to be a pivotal site targeted by Ca(2+)/calmodulin-dependent kinase II (CaMKII). Although phosphorylation of the Ser(603) residue responds to several kinds of stimuli, it is unlikely that many or all of the stimuli activate the CaMKII-involved pathway. Among the several stimulants tested in PC12 cells, bradykinin evoked the phosphorylation of Ser(603) without inducing the autophosphorylation of CaMKII, which was determined using phosphorylation site-specific antibodies against phospho-Ser(603)-synapsin I (pS603-Syn I-Ab) and phospho-Thr(286/287)-CaMKII. The bradykinin-evoked phosphorylation of Ser(603) was not suppressed by the CaMKII inhibitor KN62, whereas high KCl-evoked phosphorylation was accompanied by CaMKII autophosphorylation and inhibited by KN62. Thus, we attempted to identify Ser(603) kinase(s) besides CaMKII. We consequently detected four and three fractions with Ca(2+)/calmodulin-independent Ser(603) kinase activity on the DEAE column chromatography of bovine brain homogenate and PC12 cell lysate, respectively, two of which were purified and identified by amino acid sequence of proteolytic fragments as p21-activated kinase (PAK) 1 and PAK3. The immunoprecipitants from bovine brain homogenate with anti-PAK1 and PAK3 antibodies incorporated (32)P into synapsin I in a Cdc42/GTPgammaS-dependent manner, and its phosphorylation site was confirmed as Ser(603) using pS603-Syn I-Ab. Additionally, recombinant GST-PAK2 could phosphorylate the Ser(603) residue in the presence of Cdc42/GTPgammaS. Finally, we confirmed by immunocytochemical analysis that the transfection of constitutively active rat alphaPAK (PAK1) in PC12 cells evokes the phosphorylation of Ser(603) even in the resting mutant cells and enhances it in the bradykinin-stimulated cells, whereas that of dominant-negative alphaPAK quenches the phosphorylation. These results raise the possibility that Ser(603) on synapsin I is alternatively phosphorylated by PAKs, not only by CaMKII, in neuronal cells in response to some stimulants.