Transcriptional profiling reveals developmental relationship and distinct biological functions of CD16+ and CD16- monocyte subsets

<p>Abstract</p> <p>Background</p> <p>Human peripheral blood monocytes (Mo) consist of subsets distinguished by expression of CD16 (FCγRIII) and chemokine receptors. Classical CD16^-Mo express CCR2 and migrate in response to CCL2, while a minor CD16⁺Mo subset expresses CD16 and CX3CR1 and migrates into tissues expressing CX3CL1. CD16⁺Mo produce pro-inflammatory cytokines and are expanded in certain inflammatory conditions including sepsis and HIV infection.</p> <p>Results</p> <p>To gain insight into the developmental relationship and functions of CD16⁺and CD16^-Mo, we examined transcriptional profiles of these Mo subsets in peripheral blood from healthy individuals. Of 16,328 expressed genes, 2,759 genes were differentially expressed and 228 and 250 were >2-fold upregulated and downregulated, respectively, in CD16⁺compared to CD16^-Mo. CD16⁺Mo were distinguished by upregulation of transcripts for dendritic cell (DC) (SIGLEC10, CD43, RARA) and macrophage (MΦ) (CSF1R/CD115, MafB, CD97, C3aR) markers together with transcripts relevant for DC-T cell interaction (CXCL16, ICAM-2, LFA-1), cell activation (LTB, TNFRSF8, LST1, IFITM1-3, HMOX1, SOD-1, WARS, MGLL), and negative regulation of the cell cycle (CDKN1C, MTSS1), whereas CD16^-Mo were distinguished by upregulation of transcripts for myeloid (CD14, MNDA, TREM1, CD1d, C1qR/CD93) and granulocyte markers (FPR1, GCSFR/CD114, S100A8-9/12). Differential expression of CSF1R, CSF3R, C1QR1, C3AR1, CD1d, CD43, CXCL16, and CX3CR1 was confirmed by flow cytometry. Furthermore, increased expression of RARA and KLF2 transcripts in CD16⁺Mo coincided with absence of cell surface cutaneous lymphocyte associated antigen (CLA) expression, indicating potential imprinting for non-skin homing.</p> <p>Conclusion</p> <p>These results suggest that CD16⁺and CD16^-Mo originate from a common myeloid precursor, with CD16⁺Mo having a more MΦ – and DC-like transcription program suggesting a more advanced stage of differentiation. Distinct transcriptional programs, together with their recruitment into tissues <it>via </it>different mechanisms, also suggest that CD16⁺and CD16^-Mo give rise to functionally distinct DC and MΦ <it>in vivo</it>.</p

Identification of novel HIV-1 dependency factors in primary CCR4+CCR6+Th17 cells via a genome-wide transcriptional approach

Additional file 2: Table S2. The complete list of genes down regulated in Th17 versus Th1 subsets are included and classified based on p-values < 0.05 and FC cut-off 1.3

The Colocalization Potential of HIV-Specific CD8+ and CD4+ T-Cells is Mediated by Integrin β7 but Not CCR6 and Regulated by Retinoic Acid

CD4+ T-cells from gut-associated lymphoid tissues (GALT) are major targets for HIV-1 infection. Recruitment of excess effector CD8+ T-cells in the proximity of target cells is critical for the control of viral replication. Here, we investigated the colocalization potential of HIV-specific CD8+ and CD4+ T-cells into the GALT and explored the role of retinoic acid (RA) in regulating this process in a cohort of HIV-infected subjects with slow disease progression. The expression of the gut-homing molecules integrin β7, CCR6, and CXCR3 was identified as a “signature” for HIV-specific but not CMV-specific CD4+ T-cells thus providing a new explanation for their enhanced permissiveness to infection in vivo. HIV-specific CD8+ T-cells also expressed high levels of integrin β7 and CXCR3; however CCR6 was detected at superior levels on HIV-specific CD4+ versus CD8+ T-cells. All trans RA (ATRA) upregulated the expression of integrin β7 but not CCR6 on HIV-specific T-cells. Together, these results suggest that HIV-specific CD8+ T-cells may colocalize in excess with CD4+ T-cells into the GALT via integrin β7 and CXCR3, but not via CCR6. Considering our previous findings that CCR6+CD4+ T-cells are major cellular targets for HIV-DNA integration in vivo, a limited ability of CD8+ T-cells to migrate in the vicinity of CCR6+CD4+ T-cells may facilitate HIV replication and dissemination at mucosal sites

The Th17 Lineage: From Barrier Surfaces Homeostasis to Autoimmunity, Cancer, and HIV-1 Pathogenesis

The T helper 17 (Th17) cells represent a subset of CD4+ T-cells with unique effector functions, developmental plasticity, and stem-cell features. Th17 cells bridge innate and adaptive immunity against fungal and bacterial infections at skin and mucosal barrier surfaces. Although Th17 cells have been extensively studied in the context of autoimmunity, their role in various other pathologies is underexplored and remains an area of open investigation. This review summarizes the history of Th17 cell discovery and the current knowledge relative to the beneficial role of Th17 cells in maintaining mucosal immunity homeostasis. We further discuss the concept of Th17 pathogenicity in the context of autoimmunity, cancer, and HIV infection, and we review the most recent discoveries on molecular mechanisms regulating HIV replication/persistence in pathogenic Th17 cells. Finally, we stress the need for novel fundamental research discovery-based Th17-specific therapeutic interventions to treat pathogenic conditions associated with Th17 abnormalities, including HIV infection

The Biology of Monocytes and Dendritic Cells: Contribution to HIV Pathogenesis

Myeloid cells such as monocytes, dendritic cells (DC) and macrophages (MΦ) are key components of the innate immune system contributing to the maintenance of tissue homeostasis and the development/resolution of immune responses to pathogens. Monocytes and DC, circulating in the blood or infiltrating various lymphoid and non-lymphoid tissues, are derived from distinct bone marrow precursors and are typically short lived. Conversely, recent studies revealed that subsets of tissue resident MΦ are long-lived as they originate from embryonic/fetal precursors that have the ability to self-renew during the life of an individual. Pathogens such as the human immunodeficiency virus type 1 (HIV-1) highjack the functions of myeloid cells for viral replication (e.g., MΦ) or distal dissemination and cell-to-cell transmission (e.g., DC). Although the long-term persistence of HIV reservoirs in CD4+ T-cells during viral suppressive antiretroviral therapy (ART) is well documented, the ability of myeloid cells to harbor replication competent viral reservoirs is still a matter of debate. This review summarizes the current knowledge on the biology of monocytes and DC during homeostasis and in the context of HIV-1 infection and highlights the importance of future studies on long-lived resident MΦ to HIV persistence in ART-treated patients

Homing potential of CD8⁺ T-cells proliferating in response to HIV peptides.

<p>PBMC from five SP subjects were stimulated and stained with Abs as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032964#pone-0032964-g002" target="_blank">Figure 2</a>. At day 6 of stimulation, cells were analyzed by polychromatic flow cytometry for (<b>A</b>) the frequency of CFSE^lowCD3⁺CD4⁻ T-cells (referred to as CD8⁺ T-cells) and (<b>B–D</b>) the expression of β7 integrin, CCR6, CXCR3, and CCR4 on CFSE^lowCD8⁺ T-cells. (<b>A–B</b>) Shown are results from one donor (i.e., SP 007) generated upon stimulation with HIV Gag_705–827 peptide pool. (<b>C</b>) Shown is the expression of the homing receptors on CFSE^lowCD8⁺ T-cells specific for SEB, CMV, and different HIV peptide pools in five different SP subjects. (<b>D</b>) Shown is the homing molecule expression on matched CFSE^lowCD8⁺ T-cells specific for CMV <i>versus</i> HIV_NefGagPol peptide pool in five different SP subjects. Paired T-test p-values are indicated in the figures.</p

Preferential gut-homing potential of HIV-specific <i>versus</i> CMV-specific CD4⁺ T-cells.

<p>PBMC from SP subjects were loaded in CFSE (0.5 µM) and stimulated with different HIV Nef, Gag, Pol peptide pools (500 ng/ml), recombinant HIV-p24 (5 µg/ml), SEB (25 ng/ml), or the recombinant CMV-pp65 peptide pool (1 µg/ml) for 6 days at 37°C. Antigen-specific T-cells were identified as CFSE^low cells, as previously described <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032964#pone.0032964-Younes1" target="_blank">[52]</a>. Cells were stained with a cocktail of fluorescence-conjugated CD3, CD4, integrin β7, CCR6, CXCR3, and CCR4 Abs and analyzed by polychromatic flow cytometry for (<b>A</b>) the frequency of CFSE^lowCD3⁺CD4⁺ T-cells (referred to as CD4⁺ T-cells) and (<b>B–D</b>) the expression of integrin β7, CCR6, CXCR3, and CCR4 on antigen-specific CFSE^lowCD4⁺ T-cells. (<b>A–B</b>) Shown are results from one donor (i.e., SP 007) generated upon stimulation of PBMC with HIV Gag_705–827 peptide pool, representative of results generated with cells from five different donors. (<b>C</b>) Shown is the expression of the homing receptors on CFSE^lowCD4⁺ T-cells specific for SEB, CMV and different HIV peptide pools in five different SP subjects. (<b>D</b>) Shown is the homing molecule expression on matched CFSE^lowCD4⁺ T-cells specific for CMV <i>versus</i> HIV_NefGagPol peptide pool in four-five different SP subjects. Paired T-test p-values are indicated in the figures.</p