# HIV-1 Tat protein exposure alters the morphological characteristics and gene expression in the primary mouse cortex endothelial cells and human brain microvascular endothelial cells

## TL;DR

This study shows that HIV-1 Tat protein disrupts the structure and gene activity of brain blood vessel cells, contributing to cognitive issues in HIV patients.

## Contribution

The study reveals that Tat protein causes similar morphological and gene expression changes in mouse and human brain endothelial cells.

## Key findings

- Tat exposure reduced CD31 expression and disrupted actin cytoskeleton in both mouse and human endothelial cells.
- RNA sequencing showed upregulation of inflammatory pathways in both cell types after Tat exposure.
- Transcriptomic changes were comparable between mouse and human cells, indicating conserved mechanisms.

## Abstract

HIV-1-associated neurocognitive disorders (HAND) are highly prevalent in the era of combination of antiretroviral therapies. Recent studies suggest that damage of blood-brain barrier (BBB) may serve as an early biomarker of cognitive dysfunction in people living with HIV. This is due to the ability of HIV-1, along with infected monocytes and macrophages, to traverse the BBB via either paracellular or transcellular way. HIV-1 viral proteins have been shown to disrupt tight junctions within the BBB, thereby directly compromising its structural and functional integrity. This study determined the effects of the HIV-1 transactivator of transcription (Tat) protein on the morphological profiles and gene expression of mouse prefrontal cortex endothelial cells (ECs) and human brain microvascular endothelial cells (HBMVEC). Both mouse ECs and HBMVEC were exposed in vitro to 12.5 nM recombinant Tat1 – 86 for 48 hours. After treatment, cells were immunostained with CD31, anti-Tat, DAPI or phalloidin, and harvested for RNA sequencing to access changes in gene expression. Staining results showed a reduction in CD31 expression accompanied by an increase in phalloidin staining intensity in both mouse ECs and HBMVECs after 48-hour Tat exposure. Moreover, the phalloidin staining revealed disruption of actin cytoskeleton structure in both mouse ECs and HBMVECs after 48-hour Tat exposure. RNA sequencing analysis of mouse ECs and HBMVECs exposed to Tat displayed strikingly comparable transcriptomic signatures, as confirmed by gene set enrichment analysis (GSEA). In particular, both mouse ECs and HBMVECs showed significant upregulation of hallmark inflammatory response pathways following 48-hour Tat exposure. These findings provide mechanistic insight into HIV-1 Tat drives endothelial injury, leading to both morphological and transcriptional alterations.