Rapid Progressing Allele HLA-B35 Px Restricted Anti-HIV-1 CD8+ T Cells Recognize Vestigial CTL Epitopes

BACKGROUND: The HLA-B*35-Px allele has been associated with rapid disease progression in HIV-1 infection, in contrast to the HLA-B*35-Py allele. METHODOLOGY/PRINCIPAL FINDINGS: Immune responses to two HLA-B*35 restricted HIV-1 specific CTL epitopes and their variants were followed longitudinally during early HIV-1 infection in 16 HLA-B*35+ individuals. Subjects expressing HLA-B*35-Px alleles showed no difference in response to the consensus epitopes compared to individuals with HLA-B*35-Py alleles. Surprisingly, all the HLA-B*35-Px+ individuals responded to epitope-variants even in the absence of a consensus response. Sequencing of the viral population revealed no evidence of variant virus in any of the individuals. CONCLUSIONS/SIGNIFICANCE: This demonstrates a novel phenomenon that distinguishes individuals with the HLA-B*35-Px rapid progressing allele and those with the HLA-B*35-Py slower progressing allele

Effects of mesenchymal stromal cells versus serum on tendon healing in a controlled experimental trial in an equine model

Abstract Background Mesenchymal stromal cells (MSC) have shown promising results in the treatment of tendinopathy in equine medicine, making this therapeutic approach seem favorable for translation to human medicine. Having demonstrated that MSC engraft within the tendon lesions after local injection in an equine model, we hypothesized that they would improve tendon healing superior to serum injection alone. Methods Quadrilateral tendon lesions were induced in six horses by mechanical tissue disruption combined with collagenase application 3 weeks before treatment. Adipose-derived MSC suspended in serum or serum alone were then injected intralesionally. Clinical examinations, ultrasound and magnetic resonance imaging were performed over 24 weeks. Tendon biopsies for histological assessment were taken from the hindlimbs 3 weeks after treatment. Horses were sacrificed after 24 weeks and forelimb tendons were subjected to macroscopic and histological examination as well as analysis of musculoskeletal marker expression. Results Tendons injected with MSC showed a transient increase in inflammation and lesion size, as indicated by clinical and imaging parameters between week 3 and 6 (p < 0.05). Thereafter, symptoms decreased in both groups and, except that in MSC-treated tendons, mean lesion signal intensity as seen in T2w magnetic resonance imaging and cellularity as seen in the histology (p < 0.05) were lower, no major differences could be found at week 24. Conclusions These data suggest that MSC have influenced the inflammatory reaction in a way not described in tendinopathy studies before. However, at the endpoint of the current study, 24 weeks after treatment, no distinct improvement was observed in MSC-treated tendons compared to the serum-injected controls. Future studies are necessary to elucidate whether and under which conditions MSC are beneficial for tendon healing before translation into human medicine

CD32-Expressing CD4 T Cells Are Phenotypically Diverse and Can Contain Proviral HIV DNA.

Efforts to both characterize and eradicate the HIV reservoir have been limited by the rarity of latently infected cells and the absence of a specific denoting biomarker. CD32a (FcγRIIa) has been proposed to be a marker for an enriched CD4 T cell HIV reservoir, but this finding remains controversial. Here, we explore the expression of CD32 on CD3+CD4+ cells in participants from two primary HIV infection studies and identify at least three distinct phenotypes (CD32low, CD32+CD14+, and CD32high). Of note, CD4 negative enrichment kits remove the majority of CD4+CD32+ T cells, potentially skewing subsequent analyses if used. CD32high CD4 T cells had higher levels of HLA-DR and HIV co-receptor expression than other subsets, compatible with their being more susceptible to infection. Surprisingly, they also expressed high levels of CD20, TCRαβ, IgD, and IgM (but not IgG), markers for both T cells and naïve B cells. Compared with other populations, CD32low cells had a more differentiated memory phenotype and high levels of immune checkpoint receptors, programmed death receptor-1 (PD-1), Tim-3, and TIGIT. Within all three CD3+CD4+CD32+ phenotypes, cells could be identified in infected participants, which contained HIV DNA. CD32 expression on CD4 T cells did not correlate with HIV DNA or cell-associated HIV RNA (both surrogate measures of overall reservoir size) or predict time to rebound viremia following treatment interruption, suggesting that it is not a dominant biomarker for HIV persistence. Our data suggest that while CD32+ T cells can be infected with HIV, CD32 is not a specific marker of the reservoir although it might identify a population of HIV enriched cells in certain situations

CD32-Expressing CD4 T Cells Are Phenotypically Diverse and Can Contain Proviral HIV DNA.

Efforts to both characterize and eradicate the HIV reservoir have been limited by the rarity of latently infected cells and the absence of a specific denoting biomarker. CD32a (FcγRIIa) has been proposed to be a marker for an enriched CD4 T cell HIV reservoir, but this finding remains controversial. Here, we explore the expression of CD32 on CD3+CD4+ cells in participants from two primary HIV infection studies and identify at least three distinct phenotypes (CD32low, CD32+CD14+, and CD32high). Of note, CD4 negative enrichment kits remove the majority of CD4+CD32+ T cells, potentially skewing subsequent analyses if used. CD32high CD4 T cells had higher levels of HLA-DR and HIV co-receptor expression than other subsets, compatible with their being more susceptible to infection. Surprisingly, they also expressed high levels of CD20, TCRαβ, IgD, and IgM (but not IgG), markers for both T cells and naïve B cells. Compared with other populations, CD32low cells had a more differentiated memory phenotype and high levels of immune checkpoint receptors, programmed death receptor-1 (PD-1), Tim-3, and TIGIT. Within all three CD3+CD4+CD32+ phenotypes, cells could be identified in infected participants, which contained HIV DNA. CD32 expression on CD4 T cells did not correlate with HIV DNA or cell-associated HIV RNA (both surrogate measures of overall reservoir size) or predict time to rebound viremia following treatment interruption, suggesting that it is not a dominant biomarker for HIV persistence. Our data suggest that while CD32+ T cells can be infected with HIV, CD32 is not a specific marker of the reservoir although it might identify a population of HIV enriched cells in certain situations

Immunodominance of HIV-1 Specific CD8+ T-Cell Responses Is Related to Disease Progression Rate in Vertically Infected Adolescents

BACKGROUND: HIV-1 vertically infected children in the USA are living into adolescence and beyond with the widespread use of antiretroviral drugs. These patients exhibit striking differences in the rate of HIV-1 disease progression which could provide insights into mechanisms of control. We hypothesized that differences in the pattern of immunodomination including breadth, magnitude and polyfunctionality of HIV-1 specific CD8+ T cell response could partially explain differences in progression rate. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we mapped, quantified, and assessed the functionality of these responses against individual HIV-1 Gag peptides in 58 HIV-1 vertically infected adolescents. Subjects were divided into two groups depending upon the rate of disease progression: adolescents with a sustained CD4%≥25 were categorized as having no immune suppression (NS), and those with CD4%≤15 categorized as having severe immune suppression (SS). We observed differences in the area of HIV-1-Gag to which the two groups made responses. In addition, subjects who expressed the HLA- B*57 or B*42 alleles were highly likely to restrict their immunodominant response through these alleles. There was a significantly higher frequency of naïve CD8+ T cells in the NS subjects (p = 0.0066) compared to the SS subjects. In contrast, there were no statistically significant differences in any other CD8+ T cell subsets. The differentiation profiles and multifunctionality of Gag-specific CD8+ T cells, regardless of immunodominance, also failed to demonstrate meaningful differences between the two groups. CONCLUSIONS/SIGNIFICANCE: Together, these data suggest that, at least in vertically infected adolescents, the region of HIV-1-Gag targeted by CD8+ T cells and the magnitude of that response relative to other responses may have more importance on the rate of disease progression than their qualitative effector functions

HIV-1 Superinfection in the Antiretroviral Therapy Era: Are Seroconcordant Sexual Partners at Risk?

Acquisition of more than one strain of human immunodeficiency virus type 1 (HIV-1) has been reported to occur both during and after primary infection, but the risks and repercussions of dual and superinfection are incompletely understood. In this study, we evaluated a longitudinal cohort of chronically HIV-infected men who were sexual partners to determine if individuals acquired their partners' viral strains.Our cohort of HIV-positive men consisted of 8 couples that identified themselves as long-term sexual partners. Viral sequences were isolated from each subject and analyzed using phylogenetic methods. In addition, strain-specific PCR allowed us to search for partners' viruses present at low levels. Finally, we used computational algorithms to evaluate for recombination between partners' viral strains.All couples had at least one factor associated with increased risk for acquisition of new HIV strains during the study, including detectable plasma viral load, sexually transmitted infections, and unprotected sex. One subject was dually HIV-1 infected, but neither strain corresponded to that of his partner. Three couples' sequences formed monophyletic clusters at the entry visit, with phylogenetic analysis suggesting that one member of the couple had acquired an HIV strain from his identified partner or that both had acquired it from the same source outside their partnership. The 5 remaining couples initially displayed no evidence of dual infection, using phylogenetic analysis and strain-specific PCR. However, in 1 of these couples, further analysis revealed recombinant viral strains with segments of viral genomes in one subject that may have derived from the enrolled partner. Thus, chronically HIV-1 infected individuals may become superinfected with additional HIV strains from their seroconcordant sexual partners. In some cases, HIV-1 superinfection may become apparent when recombinant viral strains are detected

Protection of Hepatocytes from Cytotoxic T Cell Mediated Killing by Interferon-Alpha

&lt;p&gt;Background: Cellular immunity plays a key role in determining the outcome of hepatitis C virus (HCV) infection, although the majority of infections become persistent. The mechanisms behind persistence are still not clear; however, the primary site of infection, the liver, may be critical. We investigated the ability of CD8+ T-cells (CTL) to recognise and kill hepatocytes under cytokine stimulation.&lt;/p&gt; &lt;p&gt;Methods/Principle Findings: Resting hepatocytes cell lines expressed low levels of MHC Class I, but remained susceptible to CTL cytotoxicity. IFN-α treatment, in vitro, markedly increased hepatocyte MHC Class I expression, however, reduced sensitivity to CTL cytotoxicity. IFN-α stimulated hepatocyte lines were still able to present antigen and induce IFN-γ expression in interacting CTL. Resistance to killing was not due to the inhibition of the FASL/FAS- pathway, as stimulated hepatocytes were still susceptible to FAS-mediated apoptosis. In vitro stimulation with IFN-α, or the introduction of a subgenomic HCV replicon into the HepG2 line, upregulated the expression of the granzyme-B inhibitor–proteinase inhibitor 9 (PI-9). PI-9 expression was also observed in liver tissue biopsies from patients with chronic HCV infection.&lt;/p&gt; &lt;p&gt;Conclusion/Significance: IFN-α induces resistance in hepatocytes to perforin/granzyme mediate CTL killing pathways. One possible mechanism could be through the expression of the PI-9. Hindrance of CTL cytotoxicity could contribute to the chronicity of hepatic viral infections.&lt;/p&gt

Evaluation of a range of mammalian and mosquito cell lines for use in Chikungunya virus research

Chikungunya virus (CHIKV) is becoming an increasing global health issue which has spread across the globe and as far north as southern Europe. There is currently no vaccine or anti-viral treatment available. Although there has been a recent increase in CHIKV research, many of these in vitro studies have used a wide range of cell lines which are not physiologically relevant to CHIKV infection in vivo. In this study, we aimed to evaluate a panel of cell lines to identify a subset that would be both representative of the infectious cycle of CHIKV in vivo, and amenable to in vitro applications such as transfection, luciferase assays, immunofluorescence, western blotting and virus infection. Based on these parameters we selected four mammalian and two mosquito cell lines, and further characterised these as potential tools in CHIKV research

Immunity to HIV-1 Is Influenced by Continued Natural Exposure to Exogenous Virus

Unprotected sexual intercourse between individuals who are both infected with HIV-1 can lead to exposure to their partner's virus, and potentially to super-infection. However, the immunological consequences of continued exposure to HIV-1 by individuals already infected, has to our knowledge never been reported. We measured T cell responses in 49 HIV-1 infected individuals who were on antiretroviral therapy with suppressed viral loads. All the individuals were in a long-term sexual partnership with another HIV-1 infected individual, who was either also on HAART and suppressing their viral loads, or viremic (>9000 copies/ml). T cell responses to HIV-1 epitopes were measured directly ex-vivo by the IFN-γ enzyme linked immuno-spot assay and by cytokine flow cytometry. Sexual exposure data was generated from questionnaires given to both individuals within each partnership. Individuals who continued to have regular sexual contact with a HIV-1 infected viremic partner had significantly higher frequencies of HIV-1-specific T cell responses, compared to individuals with aviremic partners. Strikingly, the magnitude of the HIV-1-specific T cell response correlated strongly with the level and route of exposure. Responses consisted of both CD4+ and CD8+ T cell subsets. Longitudinally, decreases in exposure were mirrored by a lower T cell response. However, no evidence for systemic super-infection was found in any of the individuals. Continued sexual exposure to exogenous HIV-1 was associated with increased HIV-1-specific T cell responses, in the absence of systemic super-infection, and correlated with the level and type of exposure

Toll-Like Receptor 8 Agonist and Bacteria Trigger Potent Activation of Innate Immune Cells in Human Liver

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The study was supported by a Grant core funding from the Agency for Science Technology and Research (A*STAR, Singapore) and a Singapore Translational Research Investigator Award (NRMC/StaR/013/2012) to AB as well as NIHR Biomedical Centre, Oxford, WT 091663MA, NIAID1U19AI082630-01, Oxford Martin School funding and an NIHR Senior Investigator award to PK