Cyp26b1 Regulates Retinoic Acid-Dependent Signals in T Cells and Its Expression Is Inhibited by Transforming Growth Factor-β

The vitamin A metabolite, retinoic acid (RA), plays important roles in the regulation of lymphocyte properties. Dendritic cells in gut-related lymphoid organs can produce RA, thereby imprinting gut-homing specificity on T cells and enhancing transforming growth factor (TGF)-β-dependent induction of Foxp3+ regulatory T cells upon antigen presentation. In general, RA concentrations in cells and tissues are regulated by its degradation as well. However, it remained unclear if T cells could actively catabolize RA.We assessed the expression of known RA-catabolizing enzymes in T cells from mouse lymphoid tissues. Antigen-experienced CD44+ T cells in gut-related lymphoid organs selectively expressed Cyp26b1, a member of the cytochrome P450 family 26. However, T cells in the spleen or skin-draining lymph nodes did not significantly express Cyp26b1. Accordingly, physiological levels of RA (1-10 nM) could induce Cyp26b1 expression in naïve T cells upon activation in vitro, but could not do so in the presence of TGF-β. Overexpression of Cyp26b1 significantly suppressed the RA effect to induce expression of the gut-homing receptor CCR9 on T cells. On the other hand, knocking down Cyp26b1 gene expression with small interfering RNA or inhibiting CYP26 enzymatic activity led to enhancement of the RA-induced CCR9 expression.Our data demonstrate a role for CYP26B1 in regulating RA-dependent signals in activated T cells but not during TGF-β-dependent differentiation to Foxp3+ regulatory T cells. Aberrant expression of CYP26B1 may disturb T cell trafficking and differentiation in the gut and its related lymphoid organs

Sri Lankan Medical Undergraduates Awareness of Nanotechnology and Its Risks

This study examines students’ understanding of the normative connections between key concepts of nanotechnology in nanomedicine and underlying biological principles that are critical for an in-depth understanding of its therapeutic application in medical field. A structured questionnaire was distributed among randomly selected undergraduates at the Faculty of Medicine and Allied Sciences, University of Rajarata, Sri Lanka. A total of 80 students participated in this study and completed written questionnaire on nanomedicine. The outcome of this study shows that there is a strong positive response on basic knowledge on nanoscale, but the undergraduates had an average knowledge on therapeutic application related to nanomedicine. Almost all students had a good knowledge on nanoscale but they lack knowledge of the relationship between nano and nanomedicine. Specifically, students were challenged to demonstrate an integrated understanding of the nanomedicine therapeutic application. Almost 58% of them were unable to give an example of it. Also some students struggled to explain it. Furthermore, in this study it was observed that there is a positive correlation in risk benefit section related to nanomedicine. Although the outcome is preliminary in nature, the results provide cause for concern over the status of nanotechnology education in Sri Lanka which needed to be uplifted