The selective sphingosine 1-phosphate receptor modulator BAF312 redirects lymphocyte distribution and has species-specific effects on heart rate

BACKGROUND AND PURPOSE

BAF312 is a next-generation sphingosine 1-phosphate (S1P) receptor modulator, selective for S1P₁ and S1P₅ receptors. S1P₁ receptors are essential for lymphocyte egress from lymph nodes and a drug target in immune-mediated diseases. Here, we have characterized the immunomodulatory potential of BAF312 and the S1P receptor-mediated effects on heart rate using preclinical and human data.

EXPERIMENTAL APPROACH

BAF312 was tested in a rat experimental autoimmune encephalomyelitis (EAE) model. Electrophysiological recordings of G-protein-coupled inwardly rectifying potassium (GIRK) channels were carried out in human atrial myocytes. A Phase I multiple-dose trial studied the pharmacokinetics, pharmacodynamics and safety of BAF312 in 48 healthy subjects.

KEY RESULTS

BAF312 effectively suppressed EAE in rats by internalizing S1P₁ receptors, rendering them insensitive to the egress signal from lymph nodes. In healthy volunteers, BAF312 caused preferential decreases in CD4⁺ T cells, T_naïve, T_{central memory} and B cells within 4–6 h. Cell counts returned to normal ranges within a week after stopping treatment, in line with the elimination half-life of BAF312. Despite sparing S1P₃ receptors (associated with bradycardia in mice), BAF312 induced rapid, transient (day 1 only) bradycardia in humans. BAF312-mediated activation of GIRK channels in human atrial myocytes can fully explain the bradycardia.

CONCLUSION AND IMPLICATIONS

This study illustrates species-specific differences in S1P receptor specificity for first-dose cardiac effects. Based on its profound but rapidly reversible inhibition of lymphocyte trafficking, BAF312 may have potential as a treatment for immune-mediated diseases.     

Ultrasound and Doppler findings in a rare case of Castleman's disease of the parotid

Castleman''s disease of the parotid gland is an extremely rare entity, with fewer than 20 cases reported in world literature so far and only 1 previous case report describing the ultrasound findings. The Doppler findings of parotid Castleman''s disease have never been described before to the best of the authors'' knowledge. This report describes the ultrasonographic and Doppler findings in a histopathologically proven case of Castleman''s disease of the left parotid gland in a young man.     

Platelet-activating factor receptor (PAF-R)-dependent pathways control tumour growth and tumour response to chemotherapy

Background  

Phagocytosis of apoptotic cells by macrophages induces a suppressor phenotype. Previous data from our group suggested that this occurs via Platelet-activating factor receptor (PAF-R)-mediated pathways. In the present study, we investigated the impact of apoptotic cell inoculation or induction by a chemotherapeutic agent (dacarbazine, DTIC) on tumour growth, microenvironmental parameters and survival, and the effect of treatment with a PAF-R antagonist (WEB2170). These studies were performed in murine tumours: Ehrlich Ascitis Tumour (EAT) and B16F10 melanoma.     

Evidence that fibrinogen γ′ directly interferes with protofibril growth: implications for fibrin structure and clot stiffness

Summary. Background: Fibrinogen contains an alternatively spliced γ‐chain (γ′), which mainly exists as a heterodimer with the common γA‐chain (γA/γ′). Fibrinogen γ′ has been reported to inhibit thrombin and modulate fibrin structure, but the underlying mechanisms are unknown. Objective: We aimed to investigate the molecular mechanism underpinning the influence of γ′ on fibrin polymerization, structure and viscoelasticity. Methods: γA/γA and γA/γ′ fibrinogens were separated using anion exchange chromatography. Cross‐linking was controlled with purified FXIIIa and a synthetic inhibitor. Fibrin polymerization was analyzed by turbidity and gel‐point time was measured using a coagulometer. We used atomic force microscopy (AFM) to image protofibril formation while final clot structure was assessed by confocal and scanning electron microscopy. Clot viscoelasticity was measured using a magnetic microrheometer. Results: γA/γ′ fibrin formed shorter oligomers by AFM than γA/γA, which in addition gelled earlier. γA/γ′ clots displayed a non‐homogenous arrangement of thin fibers compared with the uniform arrangements of thick fibers for γA/γA clots. These differences in clot structure were not due to thrombin inhibition as demonstrated in clots made with reptilase. Non‐cross‐linked γA/γA fibrin was approximately 2.7 × stiffer than γA/γ′. Cross‐linking by FXIIIa increased the stiffness of both fibrin variants; however, the difference in stiffness increased to approximately 4.6 × (γA/γA vs. γA/γ′). Conclusions: Fibrinogen γ′ is associated with the formation of mechanically weaker, non‐uniform clots composed of thin fibers. This is caused by direct disruption of protofibril formation by γ′.     

The association between individual attachment patterns,the perceived social support,and the psychological well‐being of Turkish informal caregivers

Background: This study aimed to investigate the relations among the psychological well‐being (i.e. depression and state/trait anxiety levels), attachment patterns (i.e. secure, ambivalent, avoidant), and the perceived social support from family/friends/significant others of caregivers of cancer patients in Turkey. Methods: Fifty‐one caregivers of adult cancer patients were recruited from the oncology outpatient clinic of the Marmara Medical School Hospital in Istanbul. Caregivers were assessed with the Adult Attachment Scale, the Beck Depression Inventory, State–trait Anxiety Inventories, and the Multidimensional Scale of Perceived Social Support. Results: Stepwise multiple regression analysis indicated that depression was predicted by ambivalent attachment and the perceived social support from family. The support from significant others was the significant predictor of trait anxiety and the caregivers' ambivalent attachment score was the significant predictor of state anxiety. Conclusions: We assert that ambivalent attachment pattern could confer a vulnerability to psychological distress in cancer caregivers. Assessing the psychological experiences and needs of caregivers and being aware of possible risk factors (such as attachment patterns) and protective factors (social support network) for depression and anxiety might be helpful for successful programmes and interventions that support the caregivers of cancer patients. Copyright © 2009 John Wiley & Sons, Ltd.     

Thrombin-activatable fibrinolysis inhibitor levels in patients with non-small-cell lung cancer

BACKGROUND: An increased incidence of thromboembolic events has been described in patients with cancer. Cancer cells are attributed with producing procoagulant substances such as cysteine protease and tissue factor to activate factor X and factor VII, respectively. However, there are limited data on the pathogenesis behind this hypercoagulability state, and the thrombin generation, fibrinolytic system, and coagulation inhibition system during cancer are largely obscure. In this study, we investigated the changes of different steps of coagulation pathway in patients with non-small-cell lung cancer (NSCLC) and compared the data with those of healthy controls. PATIENTS AND METHODS: Forty-four patients with NSCLC and 36 age-matched controls were recruited for this study. Prothrombin fragment 1 + 2 (F 1 + 2) were used as a marker of thrombin generation; thrombin-activatable fibrinolysis inhibitor (TAFI) immunologic activity level was measured for inhibition of the fibrinolytic system, and tissue factor pathway inhibitor (TFPI) activity was assessed for the coagulation inhibition system. In the patient group, the relationships between TAFI activity levels and patient parameters (age, sex, body mass index [BMI], histopathology, and stage) were evaluated. RESULTS: The TAFI activity, F 1 + 2 levels, and TFPI activity were significantly higher in patients with lung cancer than in subjects in the control group (P < .05; P < .0001; and P < .0001; respectively). However, there were no statistically significant associations between TAFI activity levels and patient age, sex, BMI, histopathology, or stage of disease (P > .05). CONCLUSION: In this study, it was clearly shown that patients with lung cancer have hypercoagulable states and that the pathogenesis of thrombotic events in these patients is multifactorial. Increased TFPI is a reflection of thrombin activity in this patient group. Confirmatory studies with larger patient groups should be performed in this population.