The intracellular detection of MIP-1beta enhances the capacity to detect IFN-gamma mediated HIV-1-specific CD8 T-cell responses in a flow cytometric setting providing a sensitive alternative to the ELISPOT

Analysis of cytomegalovirus-specific T-cell responses in patients with hypertension: comparison of assay methods and antigens

Background

Recent studies suggest an association between cytomegalovirus (CMV) infection and hypertension. In the present study, we used a variety of antigens and different assay methods to investigate the relationship between CMV-specific T-cell responses and arterial stiffness in patients with hypertension.

Methods

To evaluate arterial stiffness, pulse wave velocity (PWV) was measured in 207 hypertensive patients (average age, 63 ± 8 years). To measure CMV pp65 and IE-1-specific T-cell responses, we performed intracellular cytokine staining (ICS) and enzyme-linked immunospot (ELISPOT) assays. We also analyzed CMV-specific T-cell responses against 10 different CMV antigens using ELISPOT assays.

Results

In patients with hypertension, senescent CD8⁺ T-cell frequencies were significantly correlated with arterial stiffness. Moreover, arterial stiffness was independently associated with CMV pp65-specific CD8⁺ T-cell responses as measured by ICS. CMV-specific CD8⁺ T-cell responses measured by ICS and ELISPOT assays showed good agreement and significant correlation with each other. ELISPOT analyses against 10 different CMV antigens revealed a consistent response pattern irrespective of age, gender, and diabetes

Conclusions

CMV pp65-specific CD8⁺ T-cell responses were independently correlated with arterial stiffness in patients with hypertension. Additionally, the results of ICS and ELISPOT assays showed a significant correlation and good agreement with each other. These findings are important for guiding choices regarding the broad clinical application of CMV-specific T-cell response assays in this patient population.

Development of an 8-color antibody panel for functional phenotyping of human CD8+ cytotoxic T cells from peripheral blood mononuclear cells

The study of CD8 positive cells in peripheral blood has become an essential part of research in the field of cancer immunotherapies, vaccine development, inflammation, autoimmune disease, etc. In this study, an 8-color flow cytometry panel, containing lineage and functional markers, was developed for the identification of CD8+ cytotoxic T cells in previously cryopreserved peripheral blood mononuclear cells from healthy human donors. By studying functional markers in naïve and CD3/CD28 activated T cells we demonstrate that the panel is capable of detecting protein markers corresponding to different T cell activation statuses. Data generated by flow cytometry were corroborated by different antibody based assay technologies to detect soluble cytokines. Our findings suggest that there is an inter donor variability in both baseline and activation responses. We have also successfully developed an antibody panel for flow cytometry that could be used to study cytotoxic function of CD8 T cells in clinical immunology research areas.

Norovirus-Specific Memory T Cell Responses in Adult Human Donors

Norovirus (NoV) is a leading cause of acute gastroenteritis in people of all ages worldwide. NoV-specific serum antibodies which block the binding of NoV virus-like particles (VLPs) to the cell receptors have been thoroughly investigated. In contrast, only a few publications are available on the NoV capsid VP1 protein-specific T cell responses in humans naturally infected with the virus. Freshly isolated peripheral blood mononuclear cells of eight healthy adult human donors previously exposed to NoV were stimulated with purified VLPs derived from NoV GII.4-1999, GII.4-2012 (Sydney), and GI.3, and IFN-γ production was measured by an ELISPOT assay. In addition, 76 overlapping synthetic peptides spanning the entire 539-amino acid sequence of GII.4 VP1 were pooled into two-dimensional matrices and used to identify putative T cell epitopes. Seven of the eight subjects produced IFN-γ in response to the peptides and five subjects produced IFN-γ in response to the VLPs of the same origin. In general, stronger T cell responses were induced with the peptides in each donor compared to the VLPs. A CD8⁺ T cell epitope in the shell domain of the VP1 (¹³⁴SPSQVTMFPHIIVDVRQL¹⁵¹) was identified in two subjects, both having human leukocyte antigen (HLA)-A^∗02:01 allele. To our knowledge, this is the first report using synthetic peptides to study NoV-specific T cell responses in human subjects and identify T cell epitopes.

Validation of an IFNγ/IL2 FluoroSpot assay for clinical trial monitoring

Background

The FluoroSpot assay, an advancement of the ELISpot assay, enables simultaneous measurement of different analytes secreted at a single-cell level. This allows parallel detection of several cytokines secreted by immune cells upon antigen recognition. Easier standardization, higher sensitivity and reduced labour intensity render FluoroSpot assays an interesting alternative to flow-cytometry based assays for analysis of clinical samples. While the use of immunoassays to study immunological primary and secondary endpoints becomes increasingly attractive, assays used require pre-trial validation. Here we describe the assay validation (precision, specificity and linearity) of a FluoroSpot immunological endpoint assay detecting Interferon γ (IFNγ) and Interleukin 2 (IL2) for use in clinical trial immune monitoring.

Methods

We validated an IFNγ/IL2 FluoroSpot assay to determine Epstein-Barr virus (EBV)-specific cellular immune responses (IFNγ, IL2 and double positive IFNγ + IL2 responses), using overlapping peptide pools corresponding to EBV-proteins BZLF1 and EBNA3A. Assay validation was performed using cryopreserved PBMC of 16 EBV-seropositive and 6 EBV-seronegative donors. Precision was assessed by (i) testing 16 donors using three replicates per assay (intra-assay precision/repeatability) (ii) using two plates in parallel (intermediate precision/plate-to-plate variability) and (iii) by performing the assays on three different days (inter-assay precision/reproducibility). In addition, we determined specificity, linearity and quantification limits of the assay. Further we tested precision across the two assay systems, IFNγ/IL2 FluoroSpot and the corresponding enzymatic single cytokine ELISpot.

Results

The validation revealed: (1) a high intra-assay precision (coefficient of variation (CV) 9.96, 8.85 and 13.05 %), intermediate precision (CV 6.48, 10.20 and 12.97 %) and reproducibility (CV 20.81 %, 12,75 % and 12.07 %) depending on the analyte and antigen used; (2) a specificity of 100 %; (3) a linearity with R² values from 0.93 to 0.99 depending on the analyte. The testing of the precision across the two assay systems, adduced a concordance correlation coefficient p_c = 0.99 for IFNγ responses and p_c = 0.93 for IL2 responses, indicating a large agreement between both assay methods.

Conclusions

The validated primary endpoint assay, an EBV peptide pool specific IFNγ/IL2 FluoroSpot assay was found to be suitable for the detection of EBV-specific immune responses subject to the requirement of standardized assay procedure and data analysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0932-7) contains supplementary material, which is available to authorized users.

Salmonella Typhi-specific multifunctional CD8+ T cells play a dominant role in protection from typhoid fever in humans

BACKGROUND

Typhoid fever, caused by the human-restricted organism Salmonella Typhi (S. Typhi), is a major public health problem worldwide. Development of novel vaccines remains imperative, but is hampered by an incomplete understanding of the immune responses that correlate with protection.

METHODS

Recently, a controlled human infection model was re-established in which volunteers received ~10(3) cfu wild-type S. Typhi (Quailes strain) orally. Twenty-one volunteers were evaluated for their cell-mediated immune (CMI) responses. Ex vivo PBMC isolated before and up to 1 year after challenge were exposed to three S. Typhi-infected targets, i.e., autologous B lymphoblastoid cell-lines (B-LCL), autologous blasts and HLA-E restricted AEH B-LCL cells. CMI responses were evaluated using 14-color multiparametric flow cytometry to detect simultaneously five intracellular cytokines/chemokines (i.e., IL-17A, IL-2, IFN-g, TNF-a and MIP-1b) and a marker of degranulation/cytotoxic activity (CD107a).

RESULTS

Herein we provide the first evidence that S. Typhi-specific CD8+ responses correlate with clinical outcome in humans challenged with wild-type S. Typhi. Higher multifunctional S. Typhi-specific CD8+ baseline responses were associated with protection against typhoid and delayed disease onset. Moreover, following challenge, development of typhoid fever was accompanied by decreases in circulating S. Typhi-specific CD8+ T effector/memory (TEM) with gut homing potential, suggesting migration to the site(s) of infection. In contrast, protection against disease was associated with low or no changes in circulating S. Typhi-specific TEM.

CONCLUSIONS

These studies provide novel insights into the protective immune responses against typhoid disease that will aid in selection and development of new vaccine candidates.

Immunization with Ty21a live oral typhoid vaccine elicits crossreactive multifunctional CD8+ T-cell responses against Salmonella enterica serovar Typhi, S. Paratyphi A, and S. Paratyphi B in humans

Previously we have extensively characterized Salmonella enterica serovar Typhi (S. Typhi)-specific cell-mediated immune (CMI) responses in volunteers orally immunized with the licensed Ty21a typhoid vaccine. In this study we measured Salmonella-specific multifunctional (MF) CD8+ T-cell responses to further investigate whether Ty21a elicits crossreactive CMI against S. Paratyphi A and S. Paratyphi B that also cause enteric fever. Ty21a-elicited crossreactive CMI responses against all three Salmonella serotypes were predominantly observed in CD8+ T effector/memory (T(EM)) and, to a lesser extent, in CD8+CD45RA+ T(EM) (T(EMRA)) subsets. These CD8+ T-cell responses were largely mediated by MF cells coproducing interferon-γ and macrophage inflammatory protein-1β and expressing CD107a with or without tumor necrosis factor-α. Significant proportions of Salmonella-specific MF cells expressed the gut-homing molecule integrin α4β7. In most subjects, similar MF responses were observed to S. Typhi and S. Paratyphi B, but not to S. Paratyphi A. These results suggest that Ty21a elicits MF CMI responses against Salmonella that could be critical in clearing the infection. Moreover, because S. Paratyphi A is a major public concern and Ty21a was shown in field studies not to afford cross-protection to S. Paratyphi A, these results will be important in developing a S. Typhi/S. Paratyphi A bivalent vaccine against enteric fevers.

Spontaneous control of HIV-1 viremia in a subject with protective HLA-B plus HLA-C alleles and HLA-C associated single nucleotide polymorphisms

Introduction

Understanding the mechanisms by which some individuals are able to naturally control HIV-1 infection is an important goal of AIDS research. We here describe the case of an HIV-1⁺ woman, CASE1, who has spontaneously controlled her viremia for the last 14 of her 20 years of infection.

Methods

CASE1 has been clinically monitored since 1993. Detailed immunological, virological and histological analyses were performed on samples obtained between 2009 and 2011.

Results

As for other Elite Controllers, CASE1 is characterized by low to undetectable levels of plasma HIV-1 RNA, peripheral blood mononuclear cell (PBMC) associated HIV-1 DNA and reduced in vitro susceptibility of target cells to HIV-1 infection. Furthermore, a slow rate of virus evolution was demonstrated in spite the lack of assumption of any antiretroviral agent. CASE1 failed to transmit HIV-1 to either her sexual male partner or to her child born by vaginal delivery. Normal values and ratios of T and B cells were observed, along with normal histology of the intestinal mucosa. Attempts to isolate HIV-1 from her PBMC and gut-derived cells were unsuccessful, despite expression of normal cell surface levels of CD4, CCRC5 and CXCR4. CASE1 did not produce detectable anti-HIV neutralizing antibodies in her serum or genital mucosal fluid although she displayed potent T cell responses against HIV-1 Gag and Nef. CASE1 also possessed multiple genetic polymorphisms, including HLA alleles (B*14, B*57, C*06 and C*08.02) and HLA-C single nucleotide polymorphisms (SNPs, rs9264942 C/C and rs67384697 del/del), that have been previously individually associated with spontaneous control of plasma viremia, maintenance of high CD4⁺ T cell counts and delayed disease progression.

Conclusions

CASE1 has controlled her HIV-1 viremia below the limit of detection in the absence of antiretroviral therapy for more than 14 years and has not shown any sign of immunologic deterioration or disease progression. Co-expression of multiple protective HLA alleles, HLA-C SNPs and strong T cell responses against HIV-1 proteins are the most likely explanation of this very benign case of spontaneous control of HIV-1 disease progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0335-6) contains supplementary material, which is available to authorized users.

Longitudinal changes in HIV-1-specific T-cell quality associated with viral load dynamic

BACKGROUND

Several correlates of HIV control have been described; however their predictive values remain unclear, since most studies have been performed in cross-sectional settings.

OBJECTIVES

We evaluated the cause and consequence relationship between quality of HIV-specific T-cell response and viral load dynamic in a temporal perspective.

STUDY DESIGN

HIV-1-specific T-cell responses were monitored over 7 years in a patient that following treatment interruption maintained a stable/low viral set point for 3.1 years before control of viral replication was lost and antiretroviral therapy restarted.

RESULTS

We observed that high frequencies of HIV-1-specific CD4 and CD8 T cells were unable to prevent loss of viral control. Gradual loss of functionality was observed in these responses, characterized by early loss of IL-2, viral load-dependent decrease of IFN-γ and CD154 expression as well as increase of MIP-1β production. Terminally differentiated HIV-1-specific CD8 T cells expressing CD45RA were lost independently of viral load and preceded the loss-of-control phase of HIV infection.

CONCLUSION

By describing qualitative changes in HIV-1-specific T-cell responses that coincide with loss of viral control, we identified specific correlates of disease progression and putative markers of viral control. Our findings suggest including the markers IL-2, IFN-γ, MIP-1β, CD154 and CD45RA into monitoring of HIV-specific T-cell-responses to prospectively determine correlates of protection from disease-progression.

CD34-derived dendritic cells transfected ex vivo with HIV-Gag mRNA induce polyfunctional T-cell responses in nonhuman primates

The pivotal role of DCs in initiating immune responses led to their use as vaccine vectors. However, the relationship between DC subsets involved in antigen presentation and the type of elicited immune responses underlined the need for the characterization of the DCs generated in vitro. The phenotypes of tissue-derived APCs from a cynomolgus macaque model for human vaccine development were compared with ex vivo-derived DCs. Monocyte/macrophages predominated in bone marrow (BM) and blood. Myeloid DCs (mDCs) were present in all tested tissues and were more highly represented than plasmacytoid DCs (pDCs). As in human skin, Langerhans cells (LCs) resided exclusively in the macaque epidermis, expressing CD11c, high levels of CD1a and langerin (CD207). Most DC subsets were endowed with tissue-specific combinations of PRRs. DCs generated from CD34(+) BM cells (CD34-DCs) were heterogeneous in phenotype. CD34-DCs shared properties (differentiation and PRR) of dermal and epidermal DCs. After injection into macaques, CD34-DCs expressing HIV-Gag induced Gag-specific CD4(+) and CD8(+) T cells producing IFN-γ, TNF-α, MIP-1β, or IL-2. In high responding animals, the numbers of polyfunctional CD8(+) T cells increased with the number of booster injections. This DC-based vaccine strategy elicited immune responses relevant to the DC subsets generated in vitro.

Tong Luo Jiu Nao injection, a traditional Chinese medicinal preparation, inhibits MIP-1β expression in brain microvascular endothelial cells injured by oxygen-glucose deprivation

ETHNOPHARMACOLOGICAL RELEVANCE

Tong Luo Jiu Nao injection (TLJN), a modern Chinese formula based on Traditional Chinese Medicine theory, has been used to treat ischemic stroke and vascular dementia. TLJN belongs to the ethnopharmacological family of medicines.

AIM OF THE STUDY

To investigate the protective effect of TLJN on oxygen-glucose deprivation (OGD) induced-injury of brain microvascular endothelial cells (BMECs).

MATERIALS AND METHODS

The model of OGD was established in the primarily cultured BMECs. TLJN was added to the OGD-injured BMECs for 6h. A series of assays were used to detect the effects of TLJN on: (i) MIP-1β content in BMECs conditioned media (CM) by ELISA; (ii) MIP-1β protein expression in BMECs by western blotting and immunocytochemistry; (iii) the expression of CCR5, receptor of MIP-1β, in BMECs by western blotting; (iv) the proliferative activity of microglial cells via the Cell Counting Kit-8 (CCK-8).

RESULTS

Our results showed that the OGD-injured BMECs presented with large amounts of secretion and expression of MIP-1β and up-regulation of CCR5. Also, the CM of OGD-injured BMECs remarkably increased the proliferative activity of microglial cells. The TLJN-treated BMECs exhibited a reduction of MIP-1β content in BMECs-CM and a down-regulation of MIP-1β and CCR5 expression. In addition, an inhibitory effect of CM of OGD-injured plus TLJN injection-treated BMECs on microglial proliferation was also found.

CONCLUSION

TLJN reduced the expression of MIP-1β and CCR5 in OGD-injured BMECs, and the CM of OGD-injured plus TLJN injection-treated BMECs inhibited the proliferative activity of microglial cells, suggesting the therapeutic potential of TLJN on ischemic cerebral vascular disease.

Comparison of immunologic assays for detecting immune responses in HIV immunotherapeutic studies: AIDS Clinical Trials Group Trial A5181

This study was designed to evaluate which of several T-cell-specific, immune response assays are the most relevant in measuring the key characteristics of an effective immune response to HIV-1. Using 5 HIV-1 antigens as stimulants, we assessed lymphocyte proliferation, supernatant gamma interferon (IFN-gamma) cytokine production (CP), single-cell IFN-gamma production by enzyme-linked immunospot (ELISPOT) assay, with and without Epstein-Barr virus-transformed B-lymphoblastoid cell lines (B-LCLs), and intracellular cytokine production (ICC) for IFN-gamma and interleukin 2 (IL-2) by flow cytometry. We used these to compare specimens from HIV-1-infected subjects who were virally suppressed with a stable antiretroviral therapy (ART) regimen (group A) with specimens from subjects not on ART but with HIV-1 viremia of <3,000 copies/ml (group B). The lymphocyte proliferation assay (LPA) did not significantly differentiate between the two groups. Using fresh peripheral blood mononuclear cells (PBMCs), the CP and ELISPOT assays for IFN-gamma detected the greatest differences between the two groups, specific for three of the five HIV-1 antigens, whereas significant differences were seen only in response to one antigen when cryopreserved cells were used. The strongest correlations were seen between the CP and ELISPOT assays. The ELISPOT B-LCL assay showed a cell concentration-dependent increase in IFN-gamma production compared to that shown by the standard ELISPOT assay but did not differentiate between the groups. In the ICC assay, greater numbers of IFN-gamma-producing T cells were seen in group B, and little or no detectable IL-2 production was seen in both groups. These studies highlight complexities of immunologic monitoring of T-cell responses in multisite clinical trials in HIV infection and outline considerations for optimizing these efforts.

Nef-specific CD45RA+ CD8+ T cells secreting MIP-1beta but not IFN-gamma are associated with nonprogressive HIV-1 infection

Background

Long-term survival of HIV-1 infected individuals is usually achieved by continuous administration of combination antiretroviral therapy (ART). An exception to this scenario is represented by HIV-1 infected nonprogressors (NP) which maintain relatively high circulating CD4+ T cells without clinical symptoms for several years in the absence of ART. Several lines of evidence indicate an important role of the T-cell response in the modulation of HIV-1 infection during the acute and chronic phase of the disease.

Results

We analyzed the functional and the differentiation phenotype of Nef- and Tat-specific CD8+ T cells in a cohort of HIV-1 infected NP in comparison to progressors, ART-treated seropositive individuals and individuals undergoing a single cycle of ART interruption. We observed that a distinctive feature of NP is the presence of Nef-specific CD45RA+ CD8+ T cells secreting MIP-1beta but not IFN-gamma. This population was present in 7 out of 11 NP. CD45RA+ IFN-gamma^neg MIP-1beta+ CD8+ T cells were not detected in HIV-1 infected individuals under ART or withdrawing from ART and experiencing a rebounding viral replication. In addition, we detected Nef-specific CD45RA+ IFN-gamma^neg MIP-1beta+ CD8+ T cells in only 1 out of 10 HIV-1 infected individuals with untreated progressive disease.

Conclusion

The novel antigen-specific CD45RA+ IFN-gamma^neg MIP-1beta+ CD8+ T cell population represents a new candidate marker of long-term natural control of HIV-1 disease progression and a relevant functional T-cell subset in the evaluation of the immune responses induced by candidate HIV-1 vaccines.