The role of T cell immunity in HIV-1 infection

A Δ42PD1 fusion-expressing DNA vaccine elicits enhanced adaptive immune response to HIV-1: the key role of TLR4

Since its discovery in the 1990s, the DNA vaccine has been of great interest because of its ability to elicit both humoral and cellular immune responses while showing relative advantages regarding producibility, stability and storage. However, when applied to human subjects, inadequate immunogenicity remains as the greatest challenge for the practical use of DNA vaccines. In this study, we generated a DNA vaccine Δ42PD1-P24 encoding a fusion protein comprised of the HIV-1 Gag p24 antigen and the extracellular domain of murine Δ42PD1, a novel endogenous Toll-like receptor 4 (TLR4) agonist. Using a mouse model, we found that Δ42PD1-P24 DNA vaccine elicited a higher antibody response and an increased number of IFN-γ-producing CD4 and CD8 T cells. Moreover, mice with Δ42PD1-P24 DNA vaccination were protected from a subcutaneous challenge with murine mesothelioma cells expressing the HIV-1 p24 antigen. Importantly, the Δ42PD1-mediated enhancement of immune responses was not observed in TLR4 knockout mice. Collectively, these data demonstrate that the immunogenicity and efficacy of DNA vaccines could be improved by the fusion of the extracellular domain of Δ42PD1 to target the immunogen to dendritic cells.

An exploration of how broadly neutralizing antibodies might induce HIV remission: the 'vaccinal' effect

PURPOSE OF REVIEW

Broadly neutralizing antibodies (bNAbs) are a potential new therapeutic strategy to treat HIV infection. This review explores possible mechanisms of action of bNAbs and summarizes the current evidence supporting their immunomodulatory properties, which might lead to sustained virological remission - the 'vaccinal effect'.

RECENT FINDINGS

Antiretroviral therapy (ART) is required to confer lasting HIV suppression; stopping ART almost invariably leads to HIV recrudescence from a persistent pool of virally infected cells - the HIV reservoir. HIV-specific broadly neutralizing antibodies (bNAbs) may confer viral control after ART cessation predominantly through blockade of viral entry into uninfected target cells. In some human and animal studies, HIV bNAbs also conferred lasting viral suppression after therapeutic bNAb plasma levels had declined. Immune-modulatory mechanisms have been postulated to underlie this observation - the 'vaccinal effect'. Hypothesized mechanisms include the formation of immune complexes between bNAbs and HIV envelope protein, thereby enhancing antigen presentation and uptake by immune cells, with boosted adaptive immune responses subsequently controlling the HIV reservoir.

SUMMARY

There is emerging evidence for potent antiviral efficacy of bNAb therapy. Whether bNAbs can induce sustained viral suppression after dropping below therapeutic levels remains controversial. Mechanistic data from on-going and future clinical trials will help answer these questions.

Natural killer cell counts in primary HIV infection predicts disease progression and immune restoration after treatment

The relationship between NK cell counts during primary infection and disease progression or immune restoration after antiretroviral treatment (ART) was explored. We followed 462 individuals with HIV infection and measured their NK, CD4⁺ T, CD8⁺ T cell counts and viral loads. Our data showed that individuals with high NK cell counts had much lower viral loads and higher CD4⁺ T cell counts. NK cell counts during primary infection were negatively correlated with viral set-point and viral loads at one-year-infection point, and positively correlated with CD4⁺ T cell counts at one-year-infection and one-year-ART point. Moreover, the NK cell counts during primary infection can predict HIV disease progression and immune restoration after ART. In conclusion, NK cell counts during primary infection represents a potential predictive biomarker to predict HIV disease prognosis in the clinic.

CCCH-type zinc finger antiviral protein mediates antiviral immune response by activating T cells

The zinc finger antiviral protein (ZAP), as a host restriction factor, inhibits the replication of certain viruses by binding viral mRNA or proteins for degradation. However, little is known about the role of ZAP in the antiviral immune response. We now show that ZAP participates in the antiviral immune response by activating T cells. Overexpression of ZAP significantly inhibited avian leukosis virus subgroup J (ALV-J) replication and reduced the associated inflammatory damage in vivo. In this study, we found that ZAP tended to be expressed in T lymphocytes, especially after ALV-J infection. T lymphocyte proliferation proceeded as usual in response to ALV-J infection in the presence of ZAP, indicating that ZAP endows T lymphocytes with resistance to the immunosuppression caused by ALV-J. Furthermore, ZAP activated cytokine secretion by T lymphocytes by contributing to nuclear translocation of nuclear factors of activated T cells and indirectly promoted anti-ALV-J antibody generation. Together, our findings show that ZAP, acting as an immunomodulatory factor, is involved in the antiviral immune response via T lymphocyte activation.

Reduced eIF3d accelerates HIV disease progression by attenuating CD8+ T cell function

Background

In human immunodeficiency virus (HIV) infection, 10–15% of individuals exhibit a rapid decline in CD4+ T cells and become rapid progressors (RPs). Overall, understanding the factors affecting rapid disease progression in early HIV infection (EHI) can aid in treatment initiation. Recent studies show that eIF3s, classic scaffold proteins during the translation initiation process, can directly promote or inhibit the translation of mRNA, therefore participating in the regulation of cell function. However, to our knowledge, it has not been addressed whether eIF3s are involved in the diverse prognosis of HIV infection.

Methods

Expression of eIF3s in primary cells from early or chronic HIV-infected patients was detected by real-time PCR. To investigate the potential mechanisms of eIF3d in the regulation of CD8+ T cell function, complete transcriptomes of eIF3d-inhibited Jurkat T cells were sequenced by RNA sequencing (RNA-Seq). Additionally, to examine the effect of eIF3d on CD8+ T cell function, eIF3d expression was inhibited alone or in combination with SOCS-7 knockdown by siRNA in isolated CD8+ T cells. CD8+ T cell proliferation, IFN-r secretion and apoptosis were detected by flow cytometry. Moreover, the effect of eIF3d on HIV replication was evaluated in Jurkat cells, peripheral blood mononuclear cells (PBMCs) and CD4+ T cells with eIF3d knockdown using a pNL4-3 pseudotyped virus.

Results

At approximately 100 days of infection, only eIF3d was markedly decreased in RPs compared with chronic progressors (CPs). Expression of eIF3d correlated significantly with disease progression in EHI. Based on in vitro analyses, reduced eIF3d expression led to decreased proliferation and IFN-γ secretion and increased apoptosis in CD8+ T cells. Inhibited expression of eIF3d caused enhanced expression of SOCS-7, and inhibiting SOCS-7 expression by siRNA rescued the attenuated CD8+ T cell function caused by eIF3d. Finally, when eIF3d was inhibited in Jurkat cells, PBMCs and CD4+ T cells, pNL4-3-VSV-G virus replication was enhanced.

Conclusions

The current data highlight the importance of eIF3d in HIV infection by inhibiting CD8+ T cell function and promoting viral replication. Our study provides potential targets for improved immune intervention.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1925-0) contains supplementary material, which is available to authorized users.

Characteristics of T cell receptor repertoires of patients with acute myocardial infarction through high-throughput sequencing

Background

T cells are key regulators of immunity and one of the cells recruited in atherosclerosis and participated in various stages of the development of atherosclerosis. Characterizing T-cell receptor (TCR) repertoires is a priority of great scientific interest and potential clinical utility for the early diagnosis, risk stratification and prognostic evaluation of acute myocardial infarction (AMI).

Methods

The TCR repertoires in 21 subjects including 7 patients with non-ST-segment elevation myocardial infarction (NSTEMI), 6 patients with ST-segment elevation myocardial infarction (STEMI) and 8 subjects with normal coronary artery (NCA) as control were characterized by using high-throughput sequencing. Bioinformatics analysis were performed.

Results

Patients with NSTEMI displayed more diverse TCR sequences than NCA controls, but they had lower percentage of top 200 TCR sequences. However, no significant differences were observed between the patients with STEMI and NCA controls, but STEMI group had lower percentage of top 200 TCR sequences. T cells from patients with AMI and NCA controls showed a differential V and J gene usage, especially, significant difference was observed in frequencies of V gene (TRBV2, TRBV29-1, TRBV30 and TRBV12-3) and J gene (TRBJ2-1) usage. Furthermore, significantly differences in average overlap was observed in groups of AMI and NCA control. The results showed that patients with AMI had distinct TCR repertoires which revealed the association between cardiovascular condition and T-cell clonotypes.

Conclusions

Our findings revealed the differences of TCR repertoires between patients with AMI and NCA controls, which might be potential biomarkers for evaluating risk stratification or diagnosis of acute coronary syndrome.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1768-8) contains supplementary material, which is available to authorized users.

HIV infection alters the human epigenetic landscape

Many complex diseases or traits are the results of both genetic and environmental factors. The environmental factors affect the human body by modifying its epigenetics, which controls the activity of genomes without mutating it. Viral infection is one of the common environmental factors for complex diseases. For example, the human immunodeficiency virus (HIV) infection can cause acquired immune deficiency syndrome (AIDS), HBV, and HCV infections are associated with hepatocellular carcinoma, and human papillomavirus infection is a causal factor in cervical carcinoma. In this study, to investigate how HIV infection affects DNA methylation, we analyzed the blood DNA methylation data of 485 512 sites in 44 HIV- and 142 HIV + patients. Several advanced computational methods were applied to identify the core distinctive features that were different between the HIV patients and the healthy controls. These methods can be used for differentiating HIV-infected patients from uninfected ones. These core distinctive DNA methylation features were confirmed to be functionally connected to premature aging and abnormal immune regulation, two typical pathological symptoms of HIV infection, revealing the potential regulatory mechanisms of HIV infection on the DNA methylation status of the host cells and provided novel insights on the pathogenesis of HIV infection and AIDS.

HLA-DQB1*06 and breadth of Nef core region-specific T-cell response are associated with slow disease progression in antiretroviral therapy-naive Chinese HIV-1 subtype B patients

Vaccines still are an important way to prevent and treat acquired immunodeficiency syndrome (AIDS). ¹ For developing an effective T cell-based AIDS vaccine, it is critical to define the human leukocyte antigen (HLA) type and epitope that elicit the most potent responses. This study involved 29 antiretroviral therapy-naive and chronic human immunodeficiency virus (HIV)-1 subtype B-infected individuals. A polymerase chain reaction-sequence-specific primer was used to detect the HLA typing, and the enzyme-linked immunospot assay to quantify the T-cell immune function. The results showed that the HLA-DQB1*06-positive group had higher CD4 counts and lower viral load (VL) compared with the HLA-DQB1*06-negative group; A higher magnitude of HIV-1-specific T-cell response and breadth were observed in the HLA-DQB1*06-positive group; the T-cell response was proportional to VL (R² = 0.488, P = 0.0368) in the HLA-DQB1*06-positive group. The total T-cell responses to HIV-1 Nef core region were quantified at the single-peptide level. Nine (90%) peptides were recognized in 18 (62.1%) individuals. The breath of Nef core region-specific T-cell response was correlated positively with CD4⁺ T cell count and inversely with VL, which improved disease outcomes. These data revealed that HLA-DQB1*06 had a protective effect on the course of HIV-1 and T-cell targeting of certain specific Nef epitopes, contributing to HIV-1 suppression. The results suggested the potential use of HLA-DQB1*06 and Nef core region in HIV-1 T-cell vaccine design.

Early CD4+ T Cell Responses Are Associated with Subsequent CD8+ T Cell Responses to an rAd5-Based Prophylactic Prime-Boost HIV Vaccine Strategy

Introduction

Initial evaluation of a candidate vaccine against HIV includes an assessment of the vaccine’s ability to generate immune responses. However, the dynamics of vaccine-induced immune responses are unclear. We hypothesized that the IFN-γ producing cytotoxic CD8+ (CD8+ IFN-γ+) T cell responses could be predicted by early IL-2 producing CD4+ (CD4+ IL-2+) helper T cell responses, and we evaluated this hypothesis using data from a phase I/II prophylactic HIV vaccine trial. The objective was to assess the dynamics and correlations between CD4+ IL-2+ T cell and CD8+ IFN-γ+ T cell responses after vaccination with a recombinant adenoviral serotype 5 (rAd5) HIV vaccine.

Methods

We analyzed data from the HVTN 068 HIV vaccine trial, which evaluated the immunogenicity of two different strategies for prime and boost vaccination (rAd5-rAd5 vaccine versus DNA-rAd5) in 66 healthy volunteers. Spearman correlations between immunogenicity markers across time-points were calculated. CD8+ IFN-γ+ T cell response in the rAd5-rAd5 arm was modeled as a function of CD4+ IL-2+ T cell response and time using mixed effects regression models.

Results

Moderate to high correlations (r = 0.48–0.76) were observed in the rAd5-rAd5 arm between the CD4+ IL-2+ T cell response at week 2 and later CD8+ IFN-γ+ T cell responses (weeks 2–52). Regression models confirmed this relationship with a significant association between the two markers: for a 1.0% increase in CD4+ IL-2+ T cells at week 2 post-prime, a 0.3% increase in CD8+ IFN-γ+ T cell responses across subsequent time points, including post-boost time points, was observed (p<0.01).

Conclusion

These results suggest an early and leading role of CD4+ T cells in the cellular response to the rAd5-rAd5 vaccine and in particular the stimulation of cytotoxic CD8+ T cell responses. These results could inform better timing of CD4+ T cell measurements in future clinical trials.

In silico design of a DNA-based HIV-1 multi-epitope vaccine for Chinese populations

The development of an HIV-1 vaccine that is capable of inducing effective and broadly cross-reactive humoral and cellular immune responses remains a challenging task because of the extensive diversity of HIV-1, the difference of virus subtypes (clades) in different geographical regions, and the polymorphism of human leukocyte antigens (HLA). We performed an in silico design of 3 DNA vaccines, designated pJW4303-MEG1, pJW4303-MEG2 and pJW4303-MEG3, encoding multi-epitopes that are highly conserved within the HIV-1 subtypes most prevalent in China and can be recognized through HLA alleles dominant in China. The pJW4303-MEG1-encoded protein consisted of one Th epitope in Env, and one, 2, and 6 epitopes in Pol, Env, and Gag proteins, respectively, with a GGGS linker sequence between epitopes. The pJW4303-MEG2-encoded protein contained similar epitopes in a different order, but with the same linker as pJW4303-MEG1. The pJW4303-MEG3-encoded protein contained the same epitopes in the same order as that of pJW4303-MEG2, but with a different linker sequence (AAY). To evaluate immunogenicity, mice were immunized intramuscularly with these DNA vaccines. Both pJW4303-MEG1 and pJW4303-MEG2 vaccines induced equally potent humoral and cellular immune responses in the vaccinated mice, while pJW4303-MEG3 did not induce immune responses. These results indicate that both epitope and linker sequences are important in designing effective epitope-based vaccines against HIV-1 and other viruses.

CD8 T cells and Mycobacterium tuberculosis infection

Tuberculosis is primarily a respiratory disease that is caused by Mycobacterium tuberculosis. M. tuberculosis can persist and replicate in macrophages in vivo, usually in organized cellular structures called granulomas. There is substantial evidence for the importance of CD4 T cells in control of tuberculosis, but the evidence for a requirement for CD8 T cells in this infection has not been proven in humans. However, animal model data support a non-redundant role for CD8 T cells in control of M. tuberculosis infection. In humans, infection with this pathogen leads to generation of specific CD8 T cell responses. These responses include classical (MHC Class I restricted) and non-classical CD8 T cells. Here, we discuss the potential roles of CD8 T cells in defense against tuberculosis, and our current understanding of the wide range of CD8 T cell types seen in M. tuberculosis infection.