Plasma Factors During Chronic HIV-1 Infection Impair IL-12 Secretion by Myeloid Dendritic Cells via a Virus-Independent Pathway

Abstract

Objective Myeloid dendritic cell (mDC) dysfunction during HIV infection may hinder the formation of both innate and adaptive immune responses and contribute to pathogenesis. Our objective was to determine whether circulating factors during chronic HIV infection impair mDC function with respect to secretion of IL-12, a pro-Th1 cytokine, and T cell stimulatory capacity. Particular focus was placed on the effect of combination anti-retroviral therapy (cART) and the role of HIV itself on mDC function. Methods Monocyte-derived DC (moDC) from uninfected donors were exposed to plasma from HIV-infected individuals prior to Toll-like receptor (TLR) stimulation. Cytokine secretion was measured via cytokine bead arrays, and T cell proliferation and IFNγ secretion was evaluated following co-culture with naive CD4+ T cells. Expression of genes central to TLR-mediated signal transduction was analyzed via qRT-PCR arrays and western blot. Results Exposure of moDC to plasma from untreated HIV-infected donors suppressed secretion of IL-12, and impaired Th1-skewing of CD4+ T cells. The suppressive effect was less by plasma donors receiving cART. Removal of virus from plasma did not relieve suppression, nor was IL-12 secretion decreased upon addition of HIV to control plasma. On a transcriptional level, decreased expression of IKKβ, a key regulator in the TLR/NF-kappaB signaling pathway, corresponded to suppressed cytokine secretion. Conclusions Plasma factors during chronic HIV infection impair mDC function in a manner that likely impacts the formation of immune responses to HIV, opportunistic pathogens, and vaccines. Despite partial alleviation by cART, this suppression was not directly mediated by HIV.

Soluble CD40 ligand contributes to dendritic cell-mediated T-cell dysfunction in HIV-1 infection

“…To determine whether these circulating forms of sCD40L during HIV infection may contribute to DC dysfunction, we evaluated the ability of sCD40L-exposed healthy donor DCs to produce cytokines, in particular IL-12, upon subsequent stimulation with a TLR 3 ligand, Poly-ICLC (Hiltonol, Oncovir, Inc); an established potent inducer of IL-12 secretion [4, 26-28]. IL-12 is an important regulatory cytokine that plays a pivotal role in in the differentiation of naïve CD4+ T cells towards the Th1 pathway to generate anti-viral cytotoxic T cells and IFNγ secretion[29].…”

“…The HIV-infected subjects enrolled in this cross-sectional study who donated plasma samples for immunoblot analysis of circulating sCD40L were recruited through New York University AIDS Clinical Trial Unit and the Center for AIDS Research as previously described where healthy donors served as controls [4]. The HIV-infected subjects who participated in the aspirin study were recruited and characterized as previously described [18].…”

“…1 mL of plasma each from 8 HIV-infected donors virologically suppressed on ART and 8 healthy control donors, randomly selected from our previous study[4] were processed using the ProteoMiner™ protein enrichment large-capacity kit (Bio-Rad), according to the manufacturer specification, to yield 100 uL of plasma enriched for medium- and low- abundance proteins. Enriched plasma samples and recombinant sCD40L monomeric protein and multimeric protein were separated by SDS-PAGE, transferred to PVDF membranes, and probed with mouse anti-CD40L (R&D), followed by horse anti-mouse horseradish peroxidase (HRP) –conjugated secondary antibody (Cell Signaling).…”

“…During Human Immunodeficiency Virus-1 (HIV) infection there is evidence of DC dysregulation and exhaustion, potentially contributing to generalized immune activation and inadequate adaptive immune responsiveness, which are hallmarks of HIV pathogenesis[3]. The etiology of DC dysregulation during chronic HIV infection is incompletely understood, but we have recently shown that soluble plasma factors, independent of HIV itself, are contributors[4, 5]. Improved understanding of the soluble plasma factors that lead to DC dysregulation could provide therapeutic targets to potentially decrease immune activation, inflammation, and improve adaptive immune responses during HIV infection.…”

Future considerations for dendritic cell immunotherapy against chronic viral infections

“…Eventually, this lead to reduced IFN-g secretion and proliferation of allogeneicnaive CD4 + T cells following their activation with the plasmaexposed moDCs. This virus-free inhibitory effect was lower with plasma from patients on cART [51]. Furthermore, TLR9 agonist-treated pDCs from HIV-1 patients were shown to have a reduced capacity to stimulate NK cell degranulation and expression of activation markers.…”