CANNABINOID MODULATION OF HIV-1 TAT-STIMULATED ADHESION OF MACROPHAGE-LIKE CELLS TO THE EXTRACELLULAR MATRIX

• Main Author: Drevik, Johnathan
• Format: Others
• Published: VCU Scholars Compass 2013
• Subjects: HIV-1; Tat; Cannabinoids; THC; CP55940; Macophage; Adhesion; Medicine and Health Sciences
• Online Access: http://scholarscompass.vcu.edu/etd/526; http://scholarscompass.vcu.edu/cgi/viewcontent.cgi?article=1525&context=etd

HIV-Associated Neurocognitive Disorders (HANDs) are becoming one of the largest problems in patients infected with HIV-1. The ability of infected cells such as monocytes and microglial cells to act as viral reservoirs causes extreme inflammation in the CNS and has led to several different types of neurocognitive problems. Specifically these HIV-1 infected monocytes are able to secrete inflammatory factors such as the regulatory protein Tat which acts as a chemoattractant for monocytes while also promoting the adhesion of leukocytes to the extracellular matrix (ECM). We have shown that one of the major features of the Tat protein is that it promotes cytoskeletal rearrangement resulting in increased adhesion. Specifically integrin and actin visualization was performed using confocal immunofluorescence while cytoskeletal morphology was shown with light and SEM. This microscopy work showed the Tat protein resulted in altered β1-integrin expression and distribution as well as changes in polymerized actin. These cytoskeletal changes resulted in increased adhesion to the ECM. Similarly we have also shown that these cytoskeletal changes of β1-integrin distribution and polymerized actin can be modulated through select cannabinoids THC and CP55940 that bind through the CB2 receptor which inhibits this adhesion as well as the morphological changes. The modulation of this reorganization is characteristic of a signal transduction pathway where a novel convergent point between extracellular Tat and the select cannabinoids THC and CP55940 exists. The aim of this project was to show the cytoskeletal reorganization using different microscopy techniques including light and scanning electron microscopy. This was followed by identifying and characterizing the convergent point along the signal transduction pathway linked to these changes. Different techniques were utilized in order to identify the putative convergent point in the signal transduction cascade including antibody arrays, RT-PCR, and western immunoblotting. The cytoskeletal rearrangements of β1-integrin and actin polymerization were shown successfully via light and scanning electron microscopy in the context of treatment with Tat in the presence and absence of select cannabinoids THC and CP55940. Several different pathways were identified as possibly linked to cannabinoid-mediated inhibition of signal transductional activation consequent of attachment to extracellular matrix proteins. However, the exact molecules implicated in specific signal transductional pathways as targets of cannabinoid-mediated action remain to be defined.