María Teresa Rugeles

Characterization of human invariant natural killer T subsets in health and disease using a novel invariant natural killer T cell-clonotypic monoclonal antibody, 6B11

Identification of human CD1d‐restricted T‐cell receptor (TCR)‐invariant natural killer T (iNKT) cells has been dependent on utilizing combinations of monoclonal antibodies or CD1d tetramers, which do not allow for the most specific analysis of this T‐cell subpopulation. A novel monoclonal antibody (clone 6B11), specific for the invariant CDR3 loop of human canonical Vα24Jα18 TCR α chain, was developed and used to specifically characterize iNKT cells. In healthy individuals studied for up to 1 year, a wide but stable frequency of circulating iNKT cells (range: 0·01–0·92%) was observed, with no differences in frequency by gender. Four stable iNKT cell subsets were characterized in peripheral blood based on the expression of CD4 and CD8, with CD8+ iNKT cells being a phenotypic and functionally different subset from CD4+ and double negative iNKT cells; in particular, LAG‐3 was preferentially expressed on CD8+ iNKT cells. In addition, a strong negative linear correlation between the frequency of total iNKT cells and percentage of the CD4+ subset was observed. In terms of their potential association with disease, patients at risk for type 1 diabetes had significantly expanded frequencies of double negative iNKT cells when compared to matched controls and first‐degree relatives. Moreover, peripheral blood CD4+ iNKT cells were the highest producers of interleukin‐4, while the production of interferon‐γ and tumour necrosis factor‐α was similar amongst all iNKT cell subsets. These differences in iNKT cell subsets suggest that in humans the relative ratio of iNKT cell subsets may influence susceptibility vs. resistance to immune‐mediated diseases.

Dendritic cells from HIV-1 infected individuals are less responsive to toll-like receptor (TLR) ligands

We compared TLR responsiveness in PBMC from HIV-1-infected and uninfected individuals using the TLR agonists: TLR7 (3M-001), TLR8 (3M-002), and TLR7/8 (3M-011). Activation and maturation of plasmacytoid dendritic cells (pDC) were measured by evaluating CD86, CD40, and CD83 expression and myeloid dendritic cell (mDC) activation was measured by evaluating CD40 expression. All agonists tested induced activation and maturation of pDC in PBMC cultures of cells from HIV+ and HIV- individuals. The TLR7 agonist induced significantly less pDC maturation in cells from HIV+ individuals. Quantitative assessment of secreted IFN-alpha and pro-inflammatory cytokines at the single cell level showed that pDC from HIV+ individuals stimulated with TLR7 and TLR7/8 induced IFN-alpha. TLR8 and TLR7/8 agonists induced IL-12 and COX-2 expression in mDC from HIV+ and HIV- individuals. Understanding pDC and mDC activation and maturation in HIV-1 infection could lead to more rational development of immunotherapeutic strategies to stimulate the adaptive immune response to HIV-1.

Increased Levels of Human Beta-Defensins mRNA in Sexually HIV-1 Exposed But Uninfected Individuals

Protection against HIV-1 infection in exposed seronegative (ESN) individuals likely involves natural resistance mechanisms that have not been fully elucidated. Human beta defensins (HBD) are antimicrobial peptides found primarily in mucosae, the main ports of HIV entry. HBD-2 and 3 mRNA are induced by HIV-1 in human oral epithelial cells and exhibit strong anti-HIV-1 activity; in addition, polymorphisms in the DEFB1 gene, which encodes HBD-1, have been associated with resistance/susceptibility to different infections, including HIV-1. Here, we have assessed the association of HBD expression with the ESN phenotype. Peripheral blood and vaginal/endocervical and oral mucosal samples were taken from 47 ESN, 44 seropositive (SP) and 39 healthy controls (HC). HBD-1, 2 and 3 mRNA copy numbers were quantified by real time RT-PCR and A692G/G1654A/A1836G polymorphisms in the DEFB1 gene were detected by restriction fragment length polymorphisms and confirmed by nucleotide sequencing. ESN expressed significantly greater mRNA copy numbers of HBD-2 and 3 in oral mucosa than HC; p=0.0002 and p=0.007, respectively. mRNA copy numbers of HBD-1, 2 and 3 in vaginal/endocervical mucosa from ESN and HC were similar. Homozygosity for the A692G polymorphism was significantly more frequent in ESN (0.39) than in SP (0.05) (p=0.0002). In summary, ESN exhibited enhanced mucosal expression of the innate defense genes HBD-2 and 3; however, additional studies are required to verify these results and the potential association of the A692G polymorphism to the relative resistance of ESN to HIV-1 infection.

Activation of Plasmacytoid Dendritic Cells with TLR9 Agonists Initiates Invariant NKT Cell-Mediated Cross-Talk with Myeloid Dendritic Cells

CD1d-restricted invariant NK T (iNKT) cells and dendritic cells (DCs) have been shown to play crucial roles in various types of immune responses, including TLR9-dependent antiviral responses initiated by plasmacytoid DCs (pDCs). However, the mechanism by which this occurs is enigmatic because TLRs are absent in iNKT cells and human pDCs do not express CD1d. To explore this process, pDCs were activated with CpG oligodeoxyribonucleotides, which stimulated the secretion of several cytokines such as type I and TNF-α. These cytokines and other soluble factors potently induced the expression of activation markers on iNKT cells, selectively enhanced double-negative iNKT cell survival, but did not induce their expansion or production of cytokines. Notably, pDC-derived factors licensed iNKT cells to respond to myeloid DCs: an important downstream cellular target of iNKT cell effector function and a critical contributor to the initiation of adaptive immune responses. This interaction supports the notion that iNKT cells can mediate cross-talk between DC subsets known to express mutually exclusive TLR and cytokine profiles.

Invariant NKT cells from HIV-1 or Mycobacterium tuberculosis-infected patients express an activated phenotype.

The frequency, subsets and activation status of peripheral blood invariant NKT (iNKT) cells were evaluated in pulmonary tuberculosis (TB) patients and in chronically HIV-1-infected subjects. The absolute numbers of iNKT cells were significantly decreased in TB patients and in HIV-1+ individuals who were antiretroviral therapy naive or had detectable viremia despite receiving HAART. iNKT cell subset analysis demonstrated a decreased percentage of CD4(+) iNKT cells in HIV-1+ subjects, and a decreased percentage of double negative iNKT cells in TB patients. Peripheral blood iNKT cells from HIV-1+ and TB patients had significantly increased expression of CD69, CD38, HLA-DR, CD16, CD56, and CD62L. The expression of CD25 was significantly increased only on iNKT cells from TB patients. These findings indicate that peripheral blood iNKT cells in these two chronic infections show an up-regulated expression of activation markers, suggesting their role in the immune response to infection.

Immunological characterization of compensatory anti-inflammatory response syndrome in patients with severe sepsis: a longitudinal study*.

Objectives:To perform a complete immunological characterization of compensatory anti-inflammatory response syndrome in patients with sepsis and to explore the relationship between these changes and clinical outcomes of 28-day mortality and secondary infections. Design:Prospective single-center study conducted between April 2011 and December 2012. Setting:ICUs from Hospital Universitario San Vicente Fundación at Medellin, Colombia. Patients:One hundred forty-eight patients with severe sepsis. Interventions:None. Measurements and Main Results:At days 0, 1, 3, 5, 10, and 28, we determined the expression of HLA-DR in monocytes and the apoptosis and the proliferation index in T lymphocytes, as well as the levels of tumor necrosis factor-&agr;, interleukin-6, interleukin-1&bgr;, interleukin-10, and transforming growth factor-&bgr; in both plasma and cell culture supernatants of peripheral blood mononuclear cells. The mean percentage of HLA-DR+ was 60.7 at enrollment and increased by 0.9% (95% CI, 0.7–1.2%) per day. The mean percentage of CD4 T cells and CD8 T cells AV+/7-AAD– at enrollment was 37.2% and 20.4%, respectively, but it diminished at a rate of –0.5% (95% CI, –0.7% to –0.3%) and –0.3% (95% CI, –0.4% to –0.2%) per day, respectively. Plasma levels of interleukin-6 and interleukin-10 were 290 and 166 pg/mL and decreased at a rate of –7.8 pg/mL (95% CI, –9.5 to –6.1 pg/mL) and –4 pg/mL (95% CI, –5.1 to –2.8 pg/mL) per day, respectively. After controlling for confounders, only sustained plasma levels of interleukin-6 increase the risk of death (hazard ratio 1.003; 95% CI, 1.001–1.006). Conclusions:We found no evidence to support a two-phase model of sepsis pathophysiology. However, immunological variables did behave in a mixed and time-dependent manner. Further studies should evaluate changes over time of interleukin-6 plasma levels as a prognostic biomarker for critically ill patients.

HIV-Induced T-Cell Activation/Exhaustion in Rectal Mucosa Is Controlled Only Partially by Antiretroviral Treatment

Peripheral blood T-cells from untreated HIV-1-infected patients exhibit reduced immune responses, usually associated with a hyperactivated/exhausted phenotype compared to HAART treated patients. However, it is not clear whether HAART ameliorates this altered phenotype of T-cells in the gastrointestinal-associated lymphoid tissue (GALT), the main site for viral replication. Here, we compared T-cells from peripheral blood and GALT of two groups of chronically HIV-1-infected patients: untreated patients with active viral replication, and patients on suppressive HAART. We characterized the T-cell phenotype by measuring PD-1, CTLA-4, HLA-DR, CD25, Foxp3 and granzyme A expression by flow cytometry; mRNA expression of T-bet, GATA-3, ROR-γt and Foxp3, and was also evaluated in peripheral blood mononuclear cells and rectal lymphoid cells. In HIV-1+ patients, the frequency of PD-1+ and CTLA-4+ T-cells (both CD4+ and CD8+ T cells) was higher in the GALT than in the blood. The expression of PD-1 by T-cells from GALT was higher in HIV-1-infected subjects with active viral replication compared to controls. Moreover, the expression per cell of PD-1 and CTLA-4 in CD4+ T-cells from blood and GALT was positively correlated with viral load. HAART treatment decreased the expression of CTLA-4 in CD8+ T cells from blood and GALT to levels similar as those observed in controls. Frequency of Granzyme A+ CD8+ T-cells in both tissues was low in the untreated group, compared to controls and HAART-treated patients. Finally, a switch towards Treg polarization was found in untreated patients, in both tissues. Together, these findings suggest that chronic HIV-1 infection results in an activated/exhausted T-cell phenotype, despite T-cell polarization towards a regulatory profile; these alterations are more pronounced in the GALT compared to peripheral blood, and are only partiality modulated by HAART.

The Role of Mannose Receptor on HIV‐1 Entry into Human Spermatozoa

In this opinion article we consider the possibility that human spermatozoa have receptors for human immunodeficiency virus‐1 (HIV‐1). It is clear that sperm cells have the potential for transmitting HIV‐1, but the mechanisms responsible for spreading or the virus by this vector are not known. In contrast to the traditional HIV‐1 target cells, spermatozoa do not express CD4 receptors or the CCR5/CXCR4 co‐receptors. Recent evidence indicates that astrocytes, which also do not express these molecules, can be infected with HIV‐1 through the mannose receptor. Furthermore, a 160‐kDa sperm receptor that interacts with the HIV gp 120 has been described. Therefore, we hypothesize that the mannose receptor, of 165–175 kDa, is the receptor that HIV‐1 uses to invade spermatozoa, which could lead to both vertical and horizontal transmission of HIV‐1.

Frequency of CCR5 Delta-32 Mutation in Human Immunodeficiency Virus (HIV)-seropositive and HIV-exposed Seronegative Individuals and in General Population of Medellin, Colombia

Repeated exposure to human immunodeficiency virus (HIV) does not always result in seroconversion. Modifications in coreceptors for HIV entrance to target cells are one of the factors that block the infection. We studied the frequency of Delta-32 mutation in ccr5 gene in Medellin, Colombia. Two hundred and eighteen individuals distributed in three different groups were analyzed for Delta-32 mutation in ccr5 gene by polymerase chain reaction (PCR): 29 HIV seropositive (SP), 39 exposed seronegative (ESN) and 150 individuals as a general population sample (GPS). The frequency of the Delta-32 mutant allele was 3.8% for ESN, 2.7% for GPS and 1.7% for SP. Only one homozygous mutant genotype (Delta-32/Delta-32) was found among the ESN (2.6%). The heterozygous genotype (ccr5/Delta-32) was found in eight GPS (5.3%), in one SP (3.4%) and in one ESN (2.6%). The differences in the allelic and genotypic frequencies among the three groups were not statistically significant. A comparison between the expected and the observed genotypic frequencies showed that these frequencies were significantly different for the ESN group, which indirectly suggests a protective effect of the mutant genotype (Delta-32/Delta-32). Since this mutant genotype explained the resistance of infection in only one of our ESN persons, different mechanisms of protection must be playing a more important role in this population.

Presence of HIV-1 DNA in spermatozoa from HIV-positive patients: changes in the semen parameters.

Although very inefficient, sexual transmission of HIV-1 is responsible for more than 80% of infections worldwide. Yet, the presence of HIV in spermatozoa has been a matter of debate. The aim of this study was to evaluate the presence of HIV nucleic acids and the distribution of mannose receptors in sperm cells, and to determine the semen parameters and cytokine levels in ejaculates from HIV-positive patients. The presence of non-seminal cells in purified sperm was revealed by light microscopy, flow cytometry and RT-PCR. HIV nucleic acids were evaluated by nested PCR; the distributions of mannose receptors on the surface of the sperm and cytokine levels in ejaculates were determined by fluorescence microscopy and flow cytometry respectively. Sperm characteristics were determined by conventional methods. HIV DNA was detected in 69.2% of purified sperm from HIV-positive men; in contrast all purified sperm were negative for HIV RNA. The distribution of mannose receptors and cytokine levels in HIV-1-positive men were similar to uninfected individuals. Using the Principal Component Analysis (PCA) method, it was possible to determine that semen parameters of HIV-positive men exhibit different distributions compared to HIV-negative individuals. Finally, these results indicate that viral DNA is present in purified sperm from HIV-positive men and that HIV infection of spermatozoa could be associated with lower seminal parameters as demonstrated by the PCA method. The similar distribution of mannose receptors between infected and uninfected individuals suggests that sperm cells from infected individuals interact normally with oocytes.