CD4+ T cell receptor repertoire perturbations in HIV-1 infection: association with plasma viremia and disease progression

Profiling T cell receptor β-chain in responders after immunization with recombinant hepatitis B vaccine

BACKGROUND

T cells with edited T cell receptor β-chain variable (TRBV) are involved in the immune response to recombinant hepatitis B surface antigen (rHBsAg) vaccine and the production of hepatitis B surface antibody (HBsAb). The immune repertoire (IR) profile and mechanism of vaccination positive responders (VPR) with rHBsAg are not fully understood.

METHODS

The IR of six VPRs (HBsAb+, HbsAg-) with rHBsAg vaccination was established by the high throughput sequencing technique and bioinformatics analysis and compared with those in five vaccination negative responders (VNRs) (HbsAb-, HbsAg-) who were also inoculated with rHBsAg. The repertoire features of the BV, BJ and V (CDR3) J genes and immune diversity in peripheral blood mononuclear cells, respectively, were analyzed for each subject.

RESULTS

There was no significant difference in sequencing amplification indices of each sample. However, TRBV15/BJ2-3 demonstrated significantly high expression levels in VPR compared to those in the VNR group (both p < 0.05). Further results showed that the BV15/BJ2-5 level was significantly increased for VPR compared to that of VNR group. Interestingly, the motif of CDR3 in TRBV15/BJ2-5 was mostly expressed as "GGETQ" or "GETQ". Additionally, there was no remarkable difference between the two groups of distribution with respect to the different clone expression levels of V (CDR3) J.

CONCLUSIONS

The features of IR in the VPR and VNR will contribute to the exploration of the mechanism of the positive response to rHBsAg, and also contribute to development of optimized hepatitis B vaccine, in addition to providing a partial interpretation of the VNR who has a relatively low infection with HBV.

Study of the T-cell receptor repertoire by CDR3 spectratyping

The T-cell receptor (TCR) is the key player within the so called immunological synapse and the analysis of its repertoire offers a picture of both versatility and wideness of the whole immune T-cell compartment. Among the different approaches applied to its study the so-called spectratyping identifies the pattern of the third complementarity determining region (CDR3) length distribution in each one of the beta variable (TRBV) subfamilies encoded by the corresponding genes. This technique consists in a CDR3 fragment analysis through capillary electrophoresis, performed after cell separation, RNA extraction and reverse transcriptase PCR. This review will run through the most relevant studies which have tried to dissect the TCR repertoire usage in patients with different immune-mediated and infective diseases as well as solid or haematologic malignancies.

Programming T cell Killers for an HIV Cure: Teach the New Dogs New Tricks and Let the Sleeping Dogs Lie

Despite the success of combination antiretroviral therapy (cART), a latent viral reservoir persists in HIV-1-infected persons. Unfortunately, endogenous cytotoxic T lymphocytes (CTLs) are unable to control viral rebound when patients are removed from cART. A "kick and kill" strategy has been proposed to eradicate this reservoir, whereby infected T cells are induced to express viral proteins via latency-inducing drugs followed by their elimination by CTLs. It has yet to be determined if stimulation of existing HIV-1-specific CTL will be sufficient, or if new CTLs should be primed from naïve T cells. In this review, we propose that dendritic cells (DCs), the most potent antigen presenting cells, act as dog trainers and can induce T cells (the dogs) to do magnificent tricks. We propose the hypothesis that an HIV-1 cure will require targeting of naïve T cells and will necessitate "teaching new dogs new tricks" while avoiding activation of potentially dysfunctional endogenous memory CTLs (letting the sleeping dogs lie).

Quantitative analysis of T cell receptor diversity in clinical samples of human peripheral blood

The analysis of T cell receptor diversity provides a clinically relevant and sensitive marker of repertoire loss, gain, or skewing. Spectratyping is a broadly utilized technique to measure global TCR diversity by the analysis of the lengths of CDR3 fragments in each Vβ family. However the common use of large numbers of T cells to obtain a global view of TCR Vβ CDR3 diversity has restricted spectratyping analyses when limited T-cell numbers are available in clinical setting, such as following transplant regimens. We here demonstrate that one hundred thousand T cells are sufficient to obtain a robust, highly reproducible measure of the global TCR Vβ repertoire diversity among twenty Vβ families in human peripheral blood. We also show that use of lower cell number results not in a dwindling of observed diversity but rather in non-reproducible patterns in replicate spectratypes. Finally, we report here a simple to use but sensitive method to quantify repertoire divergence in patient samples by comparison to a standard repertoire profile we generated from fifteen normal donors. We provide examples using this method to statistically evaluate the changes in the global TCR Vβ repertoire diversity that may take place during T subset immune reconstitution after hematopoietic stem cell transplantation or after immune modulating therapies.

The role of naïve T-cells in HIV-1 pathogenesis: an emerging key player

Functional naïve T-cells are critical for an effective immune response to multiple pathogens. HIV leads to a significant reduction in CD4+ naïve T-cell number and impaired function and there is incomplete recovery following combination antiretroviral therapy (cART). Here we review the basic homeostatic mechanisms that maintain naïve CD4+ T-cells and discuss recent developments in understanding the impact of HIV infection on naïve CD4+ T-cells. Finally we review therapeutic interventions in HIV-infected individuals aimed at specifically enhancing recovery of naïve CD4+ T-cells.

HIV viral diversity and escape from cellular immunity

Immune control of HIV often fails due to viral escape from cellular and humoral host immune responses. Vaccine development is a daunting task because of the ability of HIV to adapt rapidly to different selection pressures and quickly restore viral fitness when transmitted to new hosts. In addition, the global viral diversity poses significant difficulties for accurate and standardized testing of immune responses in the infected host, slowing the generation of data that are crucial to defining relevant immune correlates of controlled HIV infection. Many recent studies have shed light on some of the potentially important factors of protective immune responses and have provided further insight into the viral kinetics determining immune control, viral adaptation, and immune escape. This knowledge will likely further guide the design of broadly applicable HIV vaccine candidates.

Role of the Fas/FasL pathway in HIV or SIV disease

Human immunodeficiency virus disease involves progressive destruction of host immunity leading to opportunistic infections and increased rates for malignancies. Both depletion in immune cell numbers as well as defects in their effector functions are responsible for this immunodeficiency The broad impact of HIV reflects a similarly broad pattern of cell depletion including subsets that do not express viral receptors or support viral replication. Indirect cell killing, the destruction of uninfected cells, is due partly to activation of the Fas/FasL system for cell death. This death-signaling pathway is induced during HIV disease and contributes significantly to viral pathogenesis and disease.

Human herpesvirus replication and abnormal CD8+ T cell activation and low CD4+ T cell counts in antiretroviral-suppressed HIV-infected patients

Background

Most HIV-infected patients receiving virologically suppressive antiretroviral therapy continue to have abnormal, generalized T cell activation. We explored whether the degree of ongoing cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus (KSHV) replication was associated with higher virus-specific T cell activation and the failure to achieve normal absolute CD4+ T cell counts in the face of long-term suppressive antiretroviral therapy.

Methodology

Longitudinally collected PBMC and saliva specimens obtained from HIV-infected patients on effective antiretroviral therapy for at least one year (plasma HIV RNA <75 copies/mL) were examined using a multiplex CMV, EBV and KSHV DNA PCR assay. Eleven cases were chosen who had CD8+ T cell CD38+HLA-DR+ expression >10% and plateau absolute CD4+ T cell counts <500 cells/µL. Five controls from the same study had CD8+ T cell CD38 expression <10% and plateau absolute CD4+ T cell counts >500 cells/µL.

Results and Conclusions

Among all subjects combined, 18% of PMBC samples were positive for CMV DNA, and 27%, 73% and 24% of saliva samples were positive for CMV, EBV and KSHV DNA, respectively. No significant differences or trends were observed between cases and controls in proportions of all CMV, EBV or KSHV DNA positive specimens, proportions of subjects in each group that intermittently or continuously shed CMV, EBV or KSHV DNA in saliva, or the median number of genome copies of CMV, EBV and KSHV DNA in saliva. Overall, number of genome copies in saliva were lower for KSHV than for CMV and lower for CMV than for EBV. Although replication of CMV, EBV and KSHV persists in many antiretroviral-suppressed, HIV-infected patients, we observed no evidence in this pilot case-control study that the magnitude of such human herpesvirus replication is associated with abnormally increased CD8+ T cell activation and sub-normal plateau absolute CD4+ T cell counts following virologically suppressive antiretroviral therapy.

Transfer of Autologous Gene-modified T Cells in HIV-infected Patients with Advanced Immunodeficiency and Drug-resistant Virus

Drug toxicity and viral resistance limit the long-term efficacy of antiviral drug treatment for human immunodeficiency virus (HIV) infection. Thus, alternative therapies need to be explored. We tested the infusion of T lymphocytes transduced with a retroviral vector (M87o) that expresses an HIV entry-inhibitory peptide (maC46). Gene-modified autologous T cells were infused into ten HIV-infected patients with advanced disease and multidrug-resistant virus during anti-retroviral combination therapy. T-cell infusions were tolerated well, with no severe side effects. A significant increase of CD4 counts was observed after infusion. At the end of the 1-year follow-up, the CD4 counts of all patients were still around or above baseline. Gene-modified cells could be detected in peripheral blood, lymph nodes, and bone marrow throughout the 1-year follow-up, and marking levels correlated with the cell dose. No significant changes of viral load were observed during the first 4 months. Four of the seven patients who changed their antiviral drug regimen thereafter responded with a significant decline in plasma viral load. In conclusion, the transfer of gene-modified cells was safe, led to sustained levels of gene marking, and may improve immune competence in HIV-infected patients with advanced disease and multidrug-resistant virus.