Role of TRP Channels in Mediating the Calcium Signaling Response of Brain Endothelial Cells to Mechanical Stretch

Traumatic brain injury (TBI) often results in disruption of the blood brain barrier (BBB), which is an integral component to maintaining the central nervous system homeostasis. Recently cytosolic calcium levels ([Ca2+]i), observed to elevate following TBI, have been shown to influence endothelial barrier integrity. However, the mechanism by which TBI-induced calcium signaling alters the endothelial barrier remains unknown. In the present study, an in vitro BBB model was utilized to address this issue. Exposure of cells to biaxial mechanical stretch, in the range expected for TBI, resulted in a rapid cytosolic calcium increase. Modulation of intracellular and extracellular Ca2+ reservoirs indicated that Ca2+ influx is the major contributor for the [Ca2+]i elevation. Application of pharmacological inhibitors was used to identify the calcium-permeable channels involved in the stretch-induced Ca2+ influx. Antagonist of transient receptor potential (TRP) channel subfamilies, TRPC and TRPP, demonstrated a reduction of the stretch-induced Ca2+ influx. RNA silencing directed at individual TRP channel subtypes revealed that TRPC1 and TRPP2 largely mediate the stretch-induced Ca2+ response. In addition, we found that nitric oxide (NO) levels increased as a result of mechanical stretch, and that inhibition of TRPC1 and TRPP2 abolished the elevated NO synthesis. Further, as myosin light chain (MLC) phosphorylation and actin cytoskeleton rearrangement are correlated with endothelial barrier disruption, we investigated the effect mechanical stretch had on the myosin-actin cytoskeleton. We found that phosphorylated MLC was increased significantly by 10 minutes post-stretch, and that inhibition of TRP channel activity or NO synthesis both abolished this effect. In addition, actin stress fibers formation significantly increased 2 minutes post-stretch, and was abolished by treatment with TRP channel inhibitors. These results suggest that, in brain endothelial cells, TRPC1 and TRPP2 are activated by TBI-mechanical stress and initiate actin-myosin contraction, which may lead to disruption of the BBB.

Commercial Sexual Exploitation and Missing Children in the Coastal Region of Sao Paulo State, Brazil

The commercial sexual exploitation of children (CSEC) has emerged as one of the world’s most heinous crimes. The problem affects millions of children worldwide and no country or community is fully immune from its effects. This paper reports first generation research of the relationship that exists between CSEC and the phenomenon of missing children living in and around the coastal regions of the state of Sao Paulo, Brazil, the country’s richest State. Data are reported from interviews and case records of 64 children and adolescents, who were receiving care through a major youth serving non-governmental organization (NGO) located in the coastal city of Sao Vicente. Also, data about missing children and adolescents were collected from Police Reports – a total of 858 Police Reports. In Brazil, prostitution is not a crime itself, however, the exploitation of prostitution is a crime. Therefore, the police have no information about children or adolescents in this situation, they only have information about the clients and exploiters. Thus, this investigation sought to accomplish two objectives: 1) to establish the relationship between missing and sexual exploited children; and 2) to sensitize police and child-serving authorities in both the governmental and nongovernmental sectors to the nature, extent, and seriousness of many unrecognized cases of CSEC and missing children that come to their attention. The observed results indicated that the missing children police report are significantly underestimated. They do not represent the number of children that run away and/or are involved in commercial sexual exploitation.