Cell-type specific requirements for thiol/disulfide exchange during HIV-1 entry and infection

The role of disulfide bond remodeling in HIV-1 infection is well known, but the details remain unclear. Most prior research has used cell lines and CXCR4-tropic viruses, which may not reflect natural infection. There is uncertainty about which enzymes drive this process, with protein disulfide isomerase (PDI) and thioredoxin (Trx) being the most frequently mentioned. However, the specific contribution of each enzyme is not fully understood. This gap motivated the current study to examine CCR5-tropic HIV-1 strains and their natural targets. Primary human macrophages and CD4+ T lymphocytes were selected to better model in vivo conditions. The study aimed to clarify the role of thiol/disulfide exchange in HIV-1 entry and infection. These findings may help explain inconsistencies in prior studies and improve understanding of HIV-1 pathogenesis.

This study aimed to clarify the role of thiol/disulfide exchange in HIV-1 entry and infection. The researchers focused on CCR5-tropic HIV-1 strains and their natural targets, including macrophages and CD4+ T cells. They wanted to determine which disulfide isomerases or reductases are most involved in this process. The study also sought to establish whether the role of these enzymes varies by cell type. By using primary cells, the researchers aimed to better reflect in vivo conditions. They examined the effects of a nonspecific inhibitor and specific antibodies to PDI and Trx. The goal was to identify which enzyme plays a greater role in different cell types. The findings could help explain discrepancies in prior studies and inform future therapeutic strategies.

The researchers used a nonspecific thiol/disulfide exchange inhibitor called DTNB to assess its effect on HIV-1 entry and infection. They tested this inhibitor in cell lines, macrophages, and primary T cells. Specific monoclonal antibodies against PDI and Trx were also used to evaluate their individual contributions. The study included both HIV-1 envelope pseudotyped and wild-type virus systems. Human monocyte-derived macrophages and PHA-stimulated peripheral blood mononuclear cells were analyzed. Surface expression levels of PDI and Trx were measured in different cell types. The researchers compared results across multiple donors to account for variability. These methods allowed them to assess the role of each enzyme in HIV-1 entry and infection.

DTNB significantly reduced HIV-1 entry and infection in cell lines, macrophages, and T cells. Trx appeared to play a greater role than PDI in macrophage infection. In contrast, PDI was more involved in T cell infection. Both PDI and Trx were present on the surface of macrophages and T cells. Trx levels were lower on freshly isolated CD4+ T cells than on PHA-stimulated cells. The study showed that thiol/disulfide exchange is essential for HIV-1 entry in primary cells. The findings support a cell-type-specific role for disulfide isomerases and reductases. These results may explain differences in prior studies and highlight the importance of cell type in HIV-1 infection.

The study demonstrates that thiol/disulfide exchange is important for HIV-1 entry in primary T cells and macrophages. The role of specific enzymes varies by cell type, with Trx being more relevant to macrophages and PDI to T cells. These findings may explain inconsistencies in prior studies. The cell-type specificity of enzyme involvement is a key insight from this work. The preferential use of PDI in resting CD4+ cells may aid in virus reservoir formation. Elevated Trx levels in chronic HIV-1 infection may support macrophage infection and high viremia. The results highlight the need to consider cell type when studying HIV-1 entry mechanisms. These conclusions are based on the authors' interpretation of their findings.