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 Valpha24Jalpha18 TCR alpha 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-gamma and tumour necrosis factor-alpha 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.

Defective antigen-presenting cell function in human neonates

Immaturity of the immune system has been suggested as an underlying factor for the high rate of morbidity and mortality from infections in newborns. Functional impairment of neonatal T cells is frequently quoted as the main underlying mechanism for such immaturity. However, recent studies suggest that neonatal antigen-presenting cells (APCs) also exhibit functional alterations, which could lead to secondary defects of adaptive T-cell responses. In this review, we summarize what is known on the functionality of APC at birth and during early childhood. Compared to adults, neonatal APCs display markers of immaturity and produce low levels of cytokines. Multiple factors could be involved in neonatal APC alteration, such as intrinsic immaturity, defective interaction between APCs and T cells and regulatory T-cell-mediated inhibition. Characterization of the relative contribution of each mechanism is clearly needed to better understand the functional capability of the neonatal immune system.

Antibody Responses in COVID-19: A Review

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread worldwide as a severe pandemic. Although its seroprevalence is highly variable among territories, it has been reported at around 10%, but higher in health workers. Evidence regarding cross-neutralizing response between SARS-CoV and SARS-CoV-2 is still controversial. However, other previous coronaviruses may interfere with SARS-CoV-2 infection, since they are phylogenetically related and share the same target receptor. Further, the seroconversion of IgM and IgG occurs at around 12 days post onset of symptoms and most patients have neutralizing titers on days 14-20, with great titer variability. Neutralizing antibodies correlate positively with age, male sex, and severity of the disease. Moreover, the use of convalescent plasma has shown controversial results in terms of safety and efficacy, and due to the variable immune response among individuals, measuring antibody titers before transfusion is mostly required. Similarly, cellular immunity seems to be crucial in the resolution of the infection, as SARS-CoV-2-specific CD4+ and CD8+ T cells circulate to some extent in recovered patients. Of note, the duration of the antibody response has not been well established yet.

Ribonuclease is partly responsible for the HIV-1 inhibitory effect activated by HLA alloantigen recognition

OBJECTIVE

This study was performed to determine whether ribonucleases (RNases) contribute to the soluble HIV-1 inhibitory activity that results from the recognition of HLA alloantigens.

DESIGN AND METHODS

Supernatants from mixed lymphocyte reactions of peripheral blood mononuclear cells from healthy HLA-discordant individuals exhibited HIV-1 inhibitory activity (alloantigen-stimulated factors; ASF). These supernatants were tested for their sensitivity to heating (90 degrees C for 3 min), and for the presence of three RNases belonging to the RNase A superfamily: eosinophil-derived neurotoxin (EDN); RNase A; and angiogenin. Polyclonal antibodies specific for these RNases were used for Western blot analysis of the ASF, as well as for blocking the HIV-1 inhibitory activity of ASF. In addition, an RNase inhibitor (RI) was used to determine whether the anti-viral activity of ASF was due to RNase activity.

RESULTS

HIV-1 inhibitory activity of ASF was: (i). resistant to heat treatment; (ii). blocked by 58% with an antibody specific for EDN, but not with antibodies against RNase A or angiogenin; and (iii) blocked by 65-100% with an RI. Moreover, Western blot analysis with an anti-EDN antibody detected EDN in the ASF.

CONCLUSION

These findings indicate that the majority of the soluble HIV-1 inhibitory activity contained in the supernatants of mixed lymphocyte reactions is due to EDN or a closely related RNase.

Curcumin Inhibits In Vitro SARS-CoV-2 Infection In Vero E6 Cells through Multiple Antiviral Mechanisms

Due to the scarcity of therapeutic approaches for COVID-19, we investigated the antiviral and anti-inflammatory properties of curcumin against SARS-CoV-2 using in vitro models. The cytotoxicity of curcumin was evaluated using MTT assay in Vero E6 cells. The antiviral activity of this compound against SARS-CoV-2 was evaluated using four treatment strategies (i. pre-post infection treatment, ii. co-treatment, iii. pre-infection, and iv. post-infection). The D614G strain and Delta variant of SARS-CoV-2 were used, and the viral titer was quantified by plaque assay. The anti-inflammatory effect was evaluated in peripheral blood mononuclear cells (PBMCs) using qPCR and ELISA. By pre-post infection treatment, Curcumin (10 µg/mL) exhibited antiviral effect of 99% and 99.8% against DG614 strain and Delta variant, respectively. Curcumin also inhibited D614G strain by pre-infection and post-infection treatment. In addition, curcumin showed a virucidal effect against D614G strain and Delta variant. Finally, the pro-inflammatory cytokines (IL-1β, IL-6, and IL-8) released by PBMCs triggered by SARS-CoV-2 were decreased after treatment with curcumin. Our results suggest that curcumin affects the SARS-CoV-2 replicative cycle and exhibits virucidal effect with a variant/strain independent antiviral effect and immune-modulatory properties. This is the first study that showed a combined (antiviral/anti-inflammatory) effect of curcumin during SARS-CoV-2 infection. However, additional studies are required to define its use as a treatment for the COVID-19.

AL. 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.

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.

The Potential Protective Role of Vitamin D Supplementation on HIV-1 Infection

HIV infection remains a global and public health issue with the incidence increasing in some countries. Despite the fact that combination antiretroviral therapy (cART) has decreased mortality and increased the life expectancy of HIV-infected individuals, non-AIDS conditions, mainly those associated with a persistent inflammatory state, have emerged as important causes of morbidity, and mortality despite effective antiviral therapy. One of the most common comorbidities in HIV-1 patients is Vitamin D (VitD) insufficiency, as VitD is a hormone that, in addition to its physiological role in mineral metabolism, has pleiotropic effects on immune regulation. Several reports have shown that VitD levels decrease during HIV disease progression and correlate with decreased survival rates, highlighting the importance of VitD supplementation during infection. An extensive review of 29 clinical studies of VitD supplementation in HIV-infected patients showed that regardless of cART, when VitD levels were increased to normal ranges, there was a decrease in inflammation, markers associated with bone turnover, and the risk of secondary hyperparathyroidism while the anti-bacterial response was increased. Additionally, in 3 of 7 studies, VitD supplementation led to an increase in CD4+ T cell count, although its effect on viral load was inconclusive since most patients were on cART. Similarly, previous evidence from our laboratory has shown that VitD can reduce the infection of CD4+ T cells in vitro. The effect of VitD supplementation on other HIV-associated conditions, such as cardiovascular diseases, dyslipidemia or hypertension, warrants further exploration. Currently, the available evidence suggests that there is a potential role for VitD supplementation in people living with HIV-1, however, comprehensive studies are required to define an adequate supplementation protocol for these individuals.

Depression of humoral responses and phagocytic functions in vivo and in vitro by fish oil and eicosapentanoic acid

Previous studies have demonstrated that eicosapentanoic acid (EPA) has anti-inflammatory properties in both humans and experimental animals and may also depress humoral immunity in experimental animals. Our investigations showed that the addition of eicosapentanoic acid to human peripheral blood mononuclear cell cultures inhibited B cell responses to mitogenic stimulation and depressed the expression of interleukin 2 receptors in pokeweed mitogen-stimulated lymphocytes. Neutrophils were also affected in their ability to release the contents of primary and secondary granules, particularly when stimulated with antigen-antibody complexes. Similar depressions of B cell responses and neutrophil functions were observed in a normal volunteer who ingested 6 g/day of a commercially available fish oil extract (equivalent to 2.1 g of EPA/day) during a 6-week period. Phagocytosis, enzymatic release, circulating immunoglobulin levels, and the response to tetanus toxoid both in vivo and in vitro were depressed during ingestion of fish oil. Most parameters showed a trend toward normalization 6 weeks after the suspension of fish oil supplementation. These effects of fish oil extracts and EPA on phagocytosis and humoral responses may be advantageously used in the therapy of chronic inflammatory diseases and autoimmune diseases but could be a cause for concern when these compounds are used for longer periods of time and with minimal medical supervision for the prophylaxis of atherosclerosis.

Ribonucleases in HIV type 1 inhibition: effect of recombinant RNases on infection of primary T cells and immune activation-induced RNase gene and protein expression

Ribonucleases (RNases) have therapeutic potential against cancer and viral diseases and have been reported to inhibit replication of the human immunodeficiency virus type 1 (HIV-1) in chronically infected cell lines. The ribonuclease eosinophil-derived neurotoxin (EDN) is responsible for the anti-HIV-1 activity of a soluble factor produced in response to human alloantigens (ASF). Four recombinant RNases (EDN; a four amino acid extension of the N-terminus EDN, -4EDN; RNase A; and angiogenin) were tested for inhibition of HIV-1 replication in PHA blasts. All RNases showed anti-HIV-1 activity, irrespective of whether the RNases were added before, during, or 2 h after infection. Polyclonal antibodies against the four RNases blocked the antiviral activity. ASF inhibited HIV-1 replication in vitro if added up to 4 h after infection. We demonstrated that allostimulation induced EDN, RNase A, and angiogenin mRNA expression in peripheral blood mononuclear cells (PBMCs), although only EDN protein was detected. We identified monocytes and dendritic cells, but not macrophages or T cells, as EDN-producing cells. These findings raise the possibilities that multiple naturally occurring RNases may contribute to protection against HIV-1 infection and could be considered for utilization in HIV-1 therapy.

CD8+ T-Cell Response to HIV Infection in the Era of Antiretroviral Therapy

Although the combined antiretroviral therapy (cART) has decreased the deaths associated with the immune deficiency acquired syndrome (AIDS), non-AIDS conditions have emerged as an important cause of morbidity and mortality in HIV-infected patients under suppressive cART. Since these conditions are associated with a persistent inflammatory and immune activation state, major efforts are currently made to improve the immune reconstitution. CD8⁺ T-cells are critical in the natural and cART-induced control of viral replication; however, CD8⁺ T-cells are highly affected by the persistent immune activation and exhaustion state driven by the increased antigenic and inflammatory burden during HIV infection, inducing phenotypic and functional alterations, and hampering their antiviral response. Several CD8⁺ T-cell subsets, such as interleukin-17-producing and follicular CXCR5⁺ CD8⁺ T-cells, could play a particular role during HIV infection by promoting the gut barrier integrity, and exerting viral control in lymphoid follicles, respectively. Here, we discuss the role of CD8⁺ T-cells and some of their subpopulations during HIV infection in the context of cART-induced viral suppression, focusing on current challenges and alternatives for reaching complete reconstitution of CD8⁺ T-cells antiviral function. We also address the potential usefulness of CD8⁺ T-cell features to identify patients who will reach immune reconstitution or have a higher risk for developing non-AIDS conditions. Finally, we examine the therapeutic potential of CD8⁺ T-cells for HIV cure strategies.

HIV-1 interaction with human mannose receptor (hMR) induces production of matrix metalloproteinase 2 (MMP-2) through hMR-mediated intracellular signaling in astrocytes

Astrocytes are susceptible to HIV-1 infection. We have recently demonstrated that human mannose receptor (hMR) is directly involved in CD4-independent HIV-1 infection of astrocytes. The apparent paradox between the vivid binding affinity of HIV-1 gp120 protein to hMR and the low efficiency of hMR-mediated HIV-1 infection raises the possibility that HIV-1 binding to hMR alone may negatively affect astrocyte function. In this study, we examined the relationship between HIV-1 interaction with hMR and the production of matrix metalloproteinases (MMPs) in astrocytes. We took advantage of an astroglial cell line U87.MR stably expressing hMR as an in vitro astrocyte model system and human primary astrocytes, and demonstrated that HIV-1 binding to astrocytes induced the production of MMP-2. This induction appeared to be most potent with M-tropic HIV-1 viruses. Increased MMP-2 production was not due to hMR-mediated HIV-1 entry and/or HIV-1 viral gene expression, as the transfection of HIV-1 proviral DNA did not result in MMP-2 production, and the infection of AT-2-treated HIV-1 viruses did not inhibit MMP-2 production. Direct involvement of hMR in HIV-induced MMP-2 production was confirmed by the inhibition of the yeast mannan, an hMR ligand antagonist, and an anti-hMR serum. Furthermore, HIV-induced MMP-2 production in astrocytes was shown to involve hMR-mediated intracellular signaling. Taken together, these results suggest that HIV-1 binding to astrocytes in the absence of HIV-1 viral entry is sufficient to alter astrocyte function through hMR-mediated intracellular signaling. In addition, these results provide new evidence to support the notion that hMR is capable of eliciting intracellular signaling upon ligand binding.

Mucosa: Key Interactions Determining Sexual Transmission of the HIV Infection

In the context of HIV sexual transmission at the genital mucosa, initial interactions between the virus and the mucosal immunity determine the outcome of the exposure. Hence, these interactions have been deeply explored in attempts to undercover potential targets for developing preventative strategies. The knowledge gained has led to propose a hypothetical model for mucosal HIV transmission. Subsequent research studies on this topic further revealed new mechanisms and identified new host-HIV interactions. This review aims at integrating these findings to inform better and update the current model of HIV transmission. At the earliest stage of virus exposure, the epithelial integrity and the presence of antiviral factors are critical in preventing viral entry to the submucosa. However, the virus has been shown to enter to the submucosa in the presence of physical abrasion or via epithelial transmigration using paracellular passage or transcytosis mechanisms. The efficiency of these processes is greater with cell-associated viral inoculums and can be influenced by the presence of viral and immune factors, and by the structure of the exposed epithelium. Once the virus reaches the submucosa, dendritic cells and fibroblasts, as recently described, have been shown in vitro of being capable of facilitating the transfer of viral particles to susceptible cells, leading to viral dissemination, most likely in a trans-infection manner. The presence of activated CD4⁺ T cells in submucosa increases the probability of infection, where the predominant microbiota could be implicated through the modulation of an inflammatory microenvironment. Other factors such as genital fluids and hormones could also play an essential role in HIV transmission. Here, we review the most recent evidence described for mucosal HIV-transmission contributing with the understanding of this phenomenon.

Evidence for the presence of multilineage chimerism and progenitors of donor dendritic cells in the peripheral blood of bone marrow-augmented organ transplant recipients

We have postulated that the donor leukocyte microchimerism plays a seminal role in the acceptance of allografts by inducing and perpetuating variable degree of donor-specific nonreactivity in long-surviving organ recipients. Limited information is available, however, concerning the phenotype and function of these chimeric cells in humans. The unequivocal presence of donor dendritic cells (DCs), a prominent lineage in the microchimerism observed in rodents and clinical organ recipients, was difficult to demonstrate in bone marrow (BM)-augmented organ transplant recipients. This enigma was resolved by the recent description of a method for propagating circulating human DCs from their progenitors by culture in a medium enriched with granulocyte-macrophage colony-stimulating factor and interleukin 4, a condition known to inhibit outgrowth of monocytes, thus providing a selective growth advantage to committed progenitors of the myeloid lineage. Cells from BM-augmented organ recipients and normal control subjects harvested from 12- to 14-day cultures exhibited dendritic morphology and potent allostimulatory capacity. Using appropriate primers, the presence of donor DNA was verified by polymerase chain reaction within the lineage(null)/class II(bright) sorted DC. Phenotypic analysis of cultured DCs from BM-augmented patients, unlike that of controls, exhibited a marked down-regulation of B7-1 (CD80) while retaining normal levels of expression of B7-2 (CD86) cell surface molecules. The presence of donor DNA was also confirmed by polymerase chain reaction in individually sorted lineage+ (T, B, and NK) cells and macrophages, suggesting that the chimerism in BM-augmented patients is multilineage. The presence of progenitors of donor DCs in the peripheral blood of BM-augmented patients further substantiates the already convincing evidence of stem cell engraftment.

The interaction of CD2 with its LFA-3 ligand expressed by autologous erythrocytes results in enhancement of B cell responses

The addition of autologous erythrocytes to unfractionated human mononuclear cell cultures results in enhancement of B cell responses to antigens and mitogens. This costimulating effect of red cells is abrogated by their preincubation with anti-LFA-3 monoclonal antibody. Preincubation of mononuclear cells with anti-CD2 monoclonal antibodies (anti-Leu 5b, OKT11, used singly) has a down-regulating effect on B cell activation and no enhancement of B cell responses is seen when red cells are added to anti-CD2-treated cultures. These results demonstrate a functional effect on B cells of the interaction between the CD2 molecule on T lymphocytes and its natural ligand, LFA-3. The precise mechanism by which this costimulating effect on B lymphocytes takes place is unclear. The study of T cell populations and T cell activation markers shows that the addition of erythrocytes causes a small but reproducible increase in the number of cells expressing the IL-2 receptor and the addition of IL-2 enhances the response of mononuclear cells to antigenic stimulation in the presence of erythrocytes. However, the supernatants of mononuclear cell cultures stimulated with pokeweed mitogen in the presence of autologous erythrocytes show decreased levels of IL-2, compared to supernatants of cells stimulated with pokeweed mitogen alone. The same supernatants show increased levels of interferon-gamma, but the addition of this lymphokine to cultures stimulated with pokeweed mitogen has no potentiating effect. It is possible that the effect of erythrocytes is mediated by other growth and/or differentiation factors, and additional studies will be required to clarify this point.

Variants in LTA, TNF, IL1B and IL10 genes associated with the clinical course of sepsis

The aim of this study was to explore the association between some SNPs of the TNF, LTA, IL1B and IL10 genes with cytokine concentrations and clinical course in Colombian septic patients. We conducted a cross-sectional study to genotype 415 septic patients and 205 patients without sepsis for the SNPs -308(G/A) rs1800629 of TNF; +252 (G/A) rs909253 of LTA; -511(A/G) rs16944 and +3953(C/T) rs1143634 of IL1B; and -1082(A/G) rs1800896, -819(C/T) rs1800871 and -592(C/A) rs1800872 of IL10. The association of theses SNPs with the following parameters was evaluated: (1) the presence of sepsis; (2) severity and clinical outcomes; (3) APACHE II and SOFA scores; and (4) procalcitonin, C-reactive protein, tumor necrosis factor, lymphotoxin alpha, interleukin 1 beta and interleukin 10 plasma concentrations. We found an association between the SNP LTA +252 with the development of sepsis [OR 1.29 (1.00-1.68)]; the SNP IL10 -1082 with sepsis severity [OR 0.53 (0.29-0.97)]; the TNF -308 with mortality [OR 0.33 (0.12-0.95)]; and the IL10 -592 and IL10 -1082 with admission to the intensive care unit (ICU) [OR 3.36 (1.57-7.18)] and [OR 0.18 (0.04-0.86)], respectively. None of the SNPs were associated with cytokine levels, procalcitonin and C-reactive protein serum concentrations, nor with APACHE II and SOFA scores. Our results suggest that these genetic variants play an important role in the development of sepsis and its clinical course.

A Low Frequency of IL-17-Producing CD8+ T-Cells Is Associated With Persistent Immune Activation in People Living With HIV Despite HAART-Induced Viral Suppression

Immune activation is the hallmark of HIV infection, even in patients with highly active anti-retroviral therapy (HAART)-induced viral suppression. A major cause of immune activation during HIV infection is the intestinal microbial translocation as a consequence, among other factors, of the decrease and/or dysfunction of interleukin (IL)-17-producing T-cells, due to their role promoting the integrity of the intestinal barrier. A population of IL-17-producing CD8⁺ T-cells (Tc17 cells), characterized by the expression of CD161, has been described, but its relation with the persistent immune activation in non-viremic people living with HIV (PLWH) on HAART is unclear. By flow cytometry, we characterized the activation phenotype (evaluated by the expression of HLA-DR and CD38) of circulating CD161-expressing CD8⁺ T-cells; in addition, we explored the functionality of polyclonally-stimulated Tc17 cells in PLWH under HAART-induced viral suppression, and in healthy individuals. Finally, we determined the association of Tc17 cells with the expression of cellular and soluble activation markers. Circulating CD161-expressing CD8⁺ T-cells were decreased in PLWH compared with healthy individuals, despite their similar basal activation state. After polyclonal stimulation, IL-17 production was higher in CD8⁺ T-cells co-expressing HLA-DR and CD38 in healthy individuals. In contrast, although PLWH had a higher frequency of HLA-DR⁺ CD38⁺ CD8⁺ T-cells after stimulation, they had a lower production of IL-17. Interferon (IFN)-γ-producing CD8⁺ T-cells (Tc1 cells) were increased in PLWH. The low Tc17 cells response was associated with a high expression of CD38 and programmed death 1 protein, high levels of soluble CD14 and the treatment duration. Finally, to explore potential immunomodulatory strategies, the in vitro effect of the anti-inflammatory agent sulfasalazine was assessed on Tc17 cells. Interestingly, a decreased inflammatory environment, death of activated CD8⁺ T-cells, and an increased frequency of Tc17 cells were observed with sulfasalazine treatment. Thus, our findings suggest that activated CD8⁺ T-cells have a marked capacity to produce IL-17 in healthy individuals, but not in PLWH, despite HAART. This dysfunction of Tc17 cells is associated with the persistent immune activation observed in these patients, and can be partially restored by anti-inflammatory agents.

Incomplete normalization of regulatory t-cell frequency in the gut mucosa of Colombian HIV-infected patients receiving long-term antiretroviral treatment

INTRODUCTION

To evaluate the effect of late initiation of HAART and poor immune reconstitution on the frequency of regulatory T-cells (Treg) in the peripheral blood and gut of HIV-infected patients, we studied Colombian HIV-infected patients who had been on suppressive HAART for at least one year. They had undetectable viremia but were either immunological responders (HIR); (CD4 counts >500 cells/µl) or non-immunological responders (NIR); (CD4 T-cell count <300 cells/µl). Untreated HIV-infected patients and uninfected controls from the same region were also evaluated.

METHODS

Frequency and phenotype of regulatory T-cells (Treg) were analyzed in gut biopsies and blood samples. The functional effect of Treg depletion on CMV and HIV responses was determined. Markers of immune activation and circulating LPS levels were quantified.

RESULTS

Untreated patients exhibited high Treg frequency in PBMC and gut, and their Treg express high levels of CTLA-4 and PD-1. Although HAART significantly decreased mucosal Treg frequency, it did not normalize it in any of the treated groups (HIR and NIR patients). Treg normalization was observed in the blood of HIR patients following HAART, but did not occur in NIR patients. Treg from HIV-infected patients (treated or not) suppressed HIV and hCMV-specific T-cells from gut and blood. Plasma LPS levels and percentage of HLA-DR+CD38+ T-cells were significantly elevated in all infected groups compared to controls.

CONCLUSIONS

These findings suggest that control of viral replication is not sufficient to normalize gut Treg frequency in patients, independent of their response to HAART. Furthermore, persistence of functional Treg in the gut appears to be associated with the failure of HAART to repair mucosal damage.

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.

Particulate matter impairs immune system function by up-regulating inflammatory pathways and decreasing pathogen response gene expression

Airborne particulate matter produced by industrial sources and automobiles has been linked to increased susceptibility to infectious diseases and it is known to be recognized by cells of the immune system. The molecular mechanisms and changes in gene expression profiles induced in immune cells by PM have not been fully mapped out or systematically integrated. Here, we use RNA-seq to analyze mRNA profiles of human peripheral blood mononuclear cells after exposure to coarse particulate matter (PM10). Our analyses showed that PM10 was able to reprogram the expression of 1,196 genes in immune cells, including activation of a proinflammatory state with an increase in cytokines and chemokines. Activation of the IL-36 signaling pathway and upregulation of chemokines involved in neutrophil and monocyte recruitment suggest mechanisms for inflammation upon PM exposure, while NK cell-recruiting chemokines are repressed. PM exposure also increases transcription factors associated with inflammatory pathways (e.g., JUN, RELB, NFKB2, etc.) and reduces expression of RNases and pathogen response genes CAMP, DEFAs, AZU1, APOBEC3A and LYZ. Our analysis across gene regulatory and signaling pathways suggests that PM plays a role in the dysregulation of immune cell functions, relevant for antiviral responses and general host defense against pathogens.

Antiretroviral effect of lovastatin on HIV-1-infected individuals without highly active antiretroviral therapy (The LIVE study): a phase-II randomized clinical trial

Background

Highly active antiretroviral therapy produces a significant decrease in HIV-1 replication and allows an increase in the CD4 T-cell count, leading to a decrease in the incidence of opportunistic infections and mortality. However, the cost, side effects and complexity of antiretroviral regimens have underscored the immediate need for additional therapeutic approaches. Statins exert pleiotropic effects through a variety of mechanisms, among which there are several immunoregulatory effects, related and unrelated to their cholesterol-lowering activity that can be useful to control HIV-1 infection.

Methods/design

Randomized, double-blinded, placebo controlled, single-center, phase-II clinical trial. One hundred and ten chronically HIV-1-infected patients, older than 18 years and naïve for antirretroviral therapy (i.e., without prior or current management with antiretroviral drugs) will be enrolled at the outpatient services from the most important centres for health insurance care in Medellin-Colombia. The interventions will be lovastatin (40 mg/day, orally, for 12 months; 55 patients) or placebo (55 patients). Our primary aim will be to determine the effect of lovastatin on viral replication. The secondary aim will be to determine the effect of lovastatin on CD4+ T-cell count in peripheral blood. As tertiary aims we will explore differences in CD8+ T-cell count, expression of activation markers (CD38 and HLA-DR) on CD4 and CD8 T cells, cholesterol metabolism, LFA-1/ICAM-1 function, Rho GTPases function and clinical evolution between treated and not treated HIV-1-infected individuals.

Discussion

Preliminary descriptive studies have suggested that statins (lovastatin) may have anti HIV-1 activity and that their administration is safe, with the potential effect of controlling HIV-1 replication in chronically infected individuals who had not received antiretroviral medications. Considering that there is limited clinical data available on this topic, all these findings warrant further evaluation to determine if long-term administration of statins may benefit the virological and immunological evolution in HIV-1-infected individuals before the use of antiretroviral therapy is required.

Trial registration

Registration number NCT00721305.

Humoral Response to BNT162b2 Vaccine Against SARS-CoV-2 Variants Decays After Six Months

SARS-CoV-2 vaccines have shown very high effectiveness in real-world scenarios. However, there is compelling evidence for a fast-paced waning of immunity. The increasing number of new variants that could alter the severity, transmissibility, and potential to evade the immune response raised significant concern. Therefore, elucidating changes in the humoral immune response against viral variants induced by vaccines over time is crucial for improving immunization protocols. We carried out a 6-month longitudinal prospective study in which 60 individuals between 21 and 71 years of age who have received the complete scheme of the BNT162b2 vaccine were followed to determine titers of serum neutralizing activity. The neutralizing capacity was measured at one, three, and six-months post-vaccination by plaque reduction neutralization assay using SARS-CoV-2 B.1 (D614G) and the Gamma, Alpha, Delta, and Mu variants. Data were analyzed using GraphPad 5.0. Neutralizing activity against five different SARS-CoV-2 variants was detected in the serum samples of all vaccinated participants to a different extent after one month, with a progressive decrease according to age and gender. Overall, after one month of vaccination, the neutralizing titer was lower for all evaluated variants when compared to B.1, most remarkable against Delta and Mu, with a reduction of 83.1% and 92.3%, respectively. In addition, the Titer at 3- or 6-months follow-up decreased dramatically for all variants. Our results support the decaying of serum neutralizing activity, both over time and across SARS-CoV-2 variants, being more significant in older men. Since Delta and Mu appear to evade the neutralizing activity, these and further new variants of immune escape mutations should be considered for novel vaccine formulations.

Particular activation phenotype of T cells expressing HLA-DR but not CD38 in GALT from HIV-controllers is associated with immune regulation and delayed progression to AIDS

The spontaneous control of HIV replication in HIV-controllers underlines the importance of these subjects for exploring factors related to delayed progression. Several studies have revealed fewer immune alterations and effector mechanisms related to viral control, mainly in peripheral blood, in these individuals compared to normal progressors. However, immune characterization of gut-associated lymphoid tissue (GALT), the major target of infection, has not been thoroughly explored in these subjects. We evaluated the following parameters in GALT samples from 11 HIV-controllers and 15 HIV-progressors: (i) frequency and activation phenotype of T cells; (ii) expression of transcription factors associated with immune response profiles; and (iii) frequency of apoptotic cells. Interestingly, HIV-controllers exhibited a particular activation phenotype, with predominance of T cells expressing HLA-DR but not CD38 in GALT. This phenotype, previously associated with better control of infection, was correlated with low viral load and higher CD4(+) T cell count. Furthermore, a positive correlation of this activation phenotype with higher expression of Foxp3 and RORγT transcription factors suggested a key role for Treg and Th17 cells in the control of the immune activation and in the maintenance of gut mucosal integrity. Although we evaluated apoptosis by measuring expression of cleaved caspase-3 in GALT, we did not find differences between HIV-controllers and HIV-progressors. Taken together, our findings suggest that predominance of HLA-DR(+) T cells, along with lower immune activation and higher expression of transcription factors required for the development of Treg and Th17 cells, is associated with better viral control and delayed progression to AIDS.