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.     

p53 and MDM2 expression in odontogenic cysts and tumours

OBJECTIVE: The aim of this report was to assess p53 and MDM2 expression in odontogenic cysts and tumours, as they are known to play important roles in cell proliferation and tumorigenesis. MATERIALS AND METHODS: The expression of p53 and MDM2 proteins was determined immunohistochemically in 51 formalin-fixed, paraffin embedded specimens of odontogenic cysts and tumours.RESULTS: No positivity to p53 was found in the cases studied. MDM2 expression in ameloblastoma was higher than in radicular cysts, but lower than that observed in odontogenic keratocysts. No difference was observed between MDM2 expression in radicular cyst and adenomatoid odontogenic tumour. The clear-cell odontogenic ameloblastoma presented strong immunoreaction to this antigen.CONCLUSIONS: The results suggest that MDM2 overexpression may be involved in the pathogenesis of some odontogenic lesions.     

Effect of hepatic and renal dysfunction on disposition of bupropion in rats

Disposition of bupropion after oral administration was investigated in carbon tetrachloride (CCl4) and gentamicin treated rats. Bupropion exhibits extensive first-pass effect and is mainly cleared by hepatic route. In rats with hepatic damage, maximum plasma concentration (Cmax) was approximately 3 times higher and area under the plasma concentration-time curve up to 6 h (AUC 0-6) and AUC 0-infinity increased on an average 4 and 5 times respectively compared to the control. The half-life was doubled with hepatic dysfunction. These findings suggest that hepatic impairment in rats causes a decrease in first pass effect as well as an increase in the half-life of the drug. Rats with renal impairment, exhibited a significant increase in Cmax, AUC 0-6 and AUC 0-infinity of bupropion approximately 3-fold as compared to the control, no change in half life of the drug was observed. This indicates that rats with renal impairment show less efficient first-pass effect which may lead to increase in systemic bioavailability. The time to peak observed in all treated animals was not significantly different from the control. The percentage of bound bupropion did not differ either in CCl4 or gentamicin treated plasma as compared to the control.     

Hemolytic disease of the newborn caused by anti-Rh32 and demonstration that RN encodes rhi (Ce,Rh7)

A family is described in which the mother made anti-Rh32 as a result of pregnancy; her second liveborn child had hemolytic disease of the newborn and required an exchange transfusion. In investigating the family, it was found that the father's RN gene did not make rhi and that his second Rh gene made normal amounts of c and e but a reduced amount of f. In the two children of the couple, who inherited a normal r or Ro from their mother, the paternally derived RN encoded an amount of rhi that could be detected in direct typing tests. In the father, lack of production of rhi by RN may have represented a suppressive effect of the ce(f) gene in trans to RN or the presence of an unlinked suppressor of Rh that might also have been responsible for the reduced production of f by his r or Ro gene. The two children in this family are the first persons in whom RN has been shown to make rhi.