| Summary: | <p>Abstract</p> <p>Background</p> <p>The role of disulfide bond remodeling in HIV-1 infection is well described, but the process still remains incompletely characterized. At present, the data have been predominantly obtained using established cell lines and/or CXCR4-tropic laboratory-adapted virus strains. There is also ambiguity about which disulfide isomerases/ reductases play a major role in HIV-1 entry, as protein disulfide isomerase (PDI) and/or thioredoxin (Trx) have emerged as the two enzymes most often implicated in this process.</p> <p>Results</p> <p>We have extended our previous findings and those of others by focusing on CCR5-using HIV-1 strains and their natural targets - primary human macrophages and CD4<sup>+</sup> T lymphocytes. We found that the nonspecific thiol/disulfide exchange inhibitor, 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), significantly reduced HIV-1 entry and infection in cell lines, human monocyte-derived macrophages (MDM), and also phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC). Subsequent studies were performed using specific anti-PDI or Trx monoclonal antibodies (mAb) in HIV-1 envelope pseudotyped and wild type (wt) virus infection systems. Although human donor-to-donor variability was observed as expected, Trx appeared to play a greater role than PDI in HIV-1 infection of MDM. In contrast, PDI, but not Trx, was predominantly involved in HIV-1 entry and infection of the CD4<sup>+</sup>/CCR5<sup>+</sup> T cell line, PM-1, and PHA-stimulated primary human T lymphocytes. Intriguingly, both PDI and Trx were present on the surface of MDM, PM-1 and PHA-stimulated CD4<sup>+</sup> T cells. However, considerably lower levels of Trx were detected on freshly isolated CD4<sup>+</sup> lymphocytes, compared to PHA-stimulated cells.</p> <p>Conclusions</p> <p>Our findings clearly demonstrate the role of thiol/disulfide exchange in HIV-1 entry in primary T lymphocytes and MDM. They also establish a cell-type specificity regarding the involvement of particular disulfide isomerases/reductases in this process and may provide an explanation for differences among previously published studies. More importantly, from an <it>in vivo</it> perspective, the preferential utilization of PDI may be relevant to the HIV-1 entry and establishment of virus reservoirs in resting CD4<sup>+</sup> cells, while the elevated levels of Trx reported in the chronic stages of HIV-1 infection may facilitate the virus entry in macrophages and help to sustain high viremia during the decline of T lymphocytes.</p>
|
|---|
