Characterization of early immunological responses in primary cultures of differentially activated human peripheral mononuclear cells

PSMA-targeted polyinosine/polycytosine vector induces prostate tumor regression and invokes an antitumor immune response in mice

There is an urgent need for an effective treatment for metastatic prostate cancer (PC). Prostate tumors invariably overexpress prostate surface membrane antigen (PSMA). We designed a nonviral vector, PEI-PEG-DUPA (PPD), comprising polyethylenimine-polyethyleneglycol (PEI-PEG) tethered to the PSMA ligand, 2-[3-(1, 3-dicarboxy propyl)ureido] pentanedioic acid (DUPA), to treat PC. The purpose of PEI is to bind polyinosinic/polycytosinic acid (polyIC) and allow endosomal release, while DUPA targets PC cells. PolyIC activates multiple pathways that lead to tumor cell death and to the activation of bystander effects that harness the immune system against the tumor, attacking nontargeted neighboring tumor cells and reducing the probability of acquired resistance and disease recurrence. Targeting polyIC directly to tumor cells avoids the toxicity associated with systemic delivery. PPD selectively delivered polyIC into PSMA-overexpressing PC cells, inducing apoptosis, cytokine secretion, and the recruitment of human peripheral blood mononuclear cells (PBMCs). PSMA-overexpressing tumors in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice with partially reconstituted immune systems were significantly shrunken following PPD/polyIC treatment, in all cases. Half of the tumors showed complete regression. PPD/polyIC invokes antitumor immunity, but unlike many immunotherapies does not need to be personalized for each patient. The potent antitumor effects of PPD/polyIC should spur its development for clinical use.

EGFR-homing dsRNA activates cancer-targeted immune response and eliminates disseminated EGFR-overexpressing tumors in mice

PURPOSE

The cause of most cancer deaths is incurable dissemination of cancer cells into vital organs. Current systemic therapies for disseminated cancers provide limited efficacy and are often accompanied by toxic side effects. We have recently shown that local application of epidermal growth factor receptor (EGFR)-targeted polyinosine-cytosine (polyIC) eradicates preestablished EGFR-overexpressing tumors. Here we show for the first time the high efficiency of systemic application of polyIC/melittin-polyethyleneimine-polyethyleneglycol-EGF (polyIC/MPPE) in combination with human immune cells.

EXPERIMENTAL DESIGN

Cancer-targeted activation of immune cells was examined in vitro and in vivo following transfection with polyIC/MPPE. The therapeutic efficiency of the strategy was then examined on disseminated EGFR-overexpressing tumors grown in severe combined immunodeficient (SCID) mice.

RESULTS

Intravenous delivery of polyIC/MPPE followed by intraperitoneal injection of peripheral blood mononuclear cells induced the complete cure of SCID mice with preestablished disseminated EGFR-overexpressing tumors, with no adverse toxic effects. The immune cells and the cytokines they produce are localized to the tumor site of the treated animal and contribute decisively to the demise of the tumor cells. The immune system homes to the tumors, due to the chemokines produced by the internalized polyIC.

CONCLUSION

The EGFR-homing vector loaded with polyIC can be used to treat and possibly cure patients with disseminated EGFR-overexpressing tumors. The possibility of adopting this strategy to treat other tumors that express a protein capable of ligand induced internalization is discussed.

Evaluation of a quantitative real-time PCR assay to measure HIV-specific mucosal CD8+ T cell responses in the cervix

Several candidate HIV vaccines aim to induce virus-specific cellular immunity particularly in the genital tract, typically the initial site of HIV acquisition. However, standardized and sensitive methods for evaluating HIV-specific immune responses at the genital level are lacking. Therefore we evaluated real-time quantitative PCR (qPCR) as a potential platform to measure these responses. β-Actin and GAPDH were identified as the most stable housekeeping reference genes in peripheral blood mononuclear cells (PBMCs) and cervical mononuclear cells (CMCs) respectively and were used for normalizing transcript mRNA expression. HIV-specific cellular T cell immune responses to a pool of optimized CD8+ HIV epitopes (HIV epitope pool) and Staphylococcal enterotoxin B (SEB) superantigen control were assayed in HIV infected PBMC by qPCR, with parallel assessment of cytokine protein production. Peak HIV-specific mRNA expression of IFNγ, IL-2 and TNFα occurred after 3, 5 and 12 hours respectively. PBMCs were titrated to cervical appropriate cell numbers to determine minimum required assay input cell numbers; qPCR retained sensitivity with input of at least 2.5×10⁴ PBMCs. This optimized qPCR assay was then used to assess HIV-specific cellular T cell responses in cytobrush-derived cervical T cells from HIV positive individuals. SEB induced IFNγ mRNA transcription was detected in CMCs and correlated positively with IFNγ protein production. However, qPCR was unable to detect HIV-induced cytokine mRNA production in the cervix of HIV-infected women despite robust detection of gene induction in PBMCs. In conclusion, although qPCR can be used to measure ex vivo cellular immune responses to HIV in blood, HIV-specific responses in the cervix may fall below the threshold of qPCR detection. Nonetheless, this platform may have a potential role in measuring mitogen-induced immune responses in the genital tract.

Psychosocial adaptation and cellular immunity in breast cancer patients in the weeks after surgery: An exploratory study

BACKGROUND

The period just after surgery for breast cancer requires psychosocial adaptation and is associated with elevated distress. Distress states have been associated with decreased cellular immune functioning in this population, which could have negative effects on physical recovery. However, little is known about relations between psychological status [negative and positive mood states and overall quality of life (QOL)] and cellular signaling cytokines that could account for these associations in women undergoing treatment for breast cancer.

METHODS

The present study examined associations between psychological adaptation indicators (mood, QOL) and T-helper cell type 1 (Th1) cytokine production from stimulated peripheral mononuclear cells in women who had recently undergone surgery for early-stage breast cancer but had not yet begun adjuvant therapy. These associations were evaluated while controlling for relevant disease/treatment, sociodemographic, and health behavior covariates.

RESULTS

Lower anxiety related to greater production of the Th1 cytokine interleukin-2 (IL-2), while greater positive mood (affection) related to greater production of the Th1 cytokines IL-12 and interferon-gamma (IFN-gamma). Better QOL related to greater production of the Th1 cytokine, tumor necrosis factor-alpha (TNF-alpha).

CONCLUSION

Individual differences in psychosocial adaptation in women with breast cancer during the period after surgery relate to biological parameters that may be relevant for health and well-being as they move through treatment.

Altered innate immune response of plasmacytoid dendritic cells in multiple sclerosis

Plasmacytoid dendritic cells (pDCs) are of crucial importance in immune regulation and response to microbial factors. In multiple sclerosis (MS), pDCs from peripheral blood showed an immature phenotype, but its role in susceptibility to MS is not determined. Because infectious diseases are established triggers of exacerbations in MS, in this study we have characterized the expression of Toll-like receptors (TLR) and the maturation and functional properties of peripheral blood pDCs from clinically stable, untreated MS patients in response to signals of innate immunity. After stimulation of TLR-9, interferon (IFN)-alpha production by pDCs was significantly lower in MS (n = 12) compared to healthy controls (n = 9). In an allogenic two-step co-culture assay we found an impaired effect of TLR-9 stimulation on IFN-gamma expression of autologous naive T cells in MS patients (n = 4). In peripheral blood mononuclear cells, TLR-9 stimulation with type A CpG ODN resulted in a higher expression of TLR-1, -2, -4, -5 and -8 in MS patients (n = 7) compared with healthy controls (n = 11). These findings suggest an altered innate immune response to microbial stimuli in MS patients and may help understanding of why common infectious agents trigger MS attacks.

Nonoverlapping expression of IL10, IL12p40, and IFNgamma mRNA in the marginal zone and T cell zone of the spleen after antigenic stimulation

The differentiation of CD4(+) T cells is regulated by cytokines locally within the compartments of secondary lymphoid organs during adaptive immune responses. Quantitative data about the expression of cytokine mRNAs within the T and B cell zones of lymphoid organs are lacking. In this study, we assessed the expression of multiple cytokine genes within the lymphoid compartments of the spleen of rats after two types of stimulation. First, the spleen was stimulated directly by a blood-derived Ag. Second, the spleen was stimulated indirectly by incoming lymphocytes that had been activated and released during a proceeding immune response at a distant tissue site. Using laser microdissection, we show that the expression of cytokine mRNAs was compartment specific, transient, and preceded cell proliferation after the direct antigenic stimulation. Surprisingly, the indirect stimulation by incoming activated lymphocytes induced similar cytokines in the T cell zone. However, the nonoverlapping expression was lost and IL10 appeared as the major cytokine in all compartments. Thus, tracking two types of immune activation without disturbing the integrity of structures reveals distinct and overlapping events in the compartments of the spleen. This information adds a new dimension to the understanding of immune responses in vivo.

Novel human CD4+ T lymphocyte subpopulations defined by CD300a/c molecule expression

The CD300c (CMRF-35A) and CD300a (CMRF-35H) molecules are leukocyte surface proteins that are part of a larger family of immunoregulatory molecules encoded by a gene complex on human chromosome 17. The CMRF-35 monoclonal antibody binds to an epitope common to both molecules, expressed on most human leukocyte populations, apart from B lymphocytes and a subpopulation of CD4(+) and CD8(+) T lymphocytes. We describe the CMRF-35(pos) and CMRF-35(-) fractions of CD4(+) T lymphocytes. The CMRF-35(pos) fraction can further be divided into CMRF-35(++) and CMRF-35(+)CD4(+) T lymphocyte subpopulations. Resting peripheral CD4(+) T lymphocytes express CD300a mRNA and very low amounts of CD300c. Activation results in an initial decrease in CD300a gene expression before an increase in both CD300a and CD300c gene expression. The up-regulated expression of these genes was associated with increased CMRF-35 binding to activated T lymphocytes. The CMRF-35(-) fraction of CD4(+) T lymphocytes proliferated to a greater extent than the CMRF-35(pos) fraction, in response to mitogens or allogeneic antigen. The poor proliferation of the CMRF-35(pos) CD4(+) in response to mitogens was explained by increased apoptosis within this subpopulation. The recall antigen, tetanus toxoid, stimulated the CMRF-35(++)CD4(+)CD45RO(+) but not the CMRF-35(-)CD4(+)CD45RO(+) subpopulation. Resting CMRF-35(++) CD4(+) lymphocytes express low levels of IFN-gamma mRNA. Within 18 h following in vitro activation, CMRF-35(++) CD4(+) lymphocytes express more IFN-gamma mRNA and protein compared with the CMRF-35(-)CD4(+) lymphocytes, however, after 24 h, both the CMRF-35(+) and CMRF-35(-)CD4(+) T lymphocytes were able to produce IFN-gamma. The CMRF-35(++)CD4(+) T lymphocyte population contains the Th(1) memory effector cells.

Characterization of surface interleukin-2 receptor expression on gated populations of peripheral blood mononuclear cells from manatees, Trichechus manatus latirostris

An in vitro system to determine surface interleukin-2 receptor (IL-2R) expression on mitogen-stimulated peripheral blood mononuclear cells (PBMC) from free-ranging manatees, Trichechus manatus latirostris was developed. Human recombinant IL-2, conjugated with a fluorescein dye was used in conjunction with flow cytometric analysis to determine changes in surface expression of IL-2R at sequential times over a 48-h period of in vitro stimulation. Surface expression of IL-2R was detected on manatee PBMC, which also cross-reacted with an anti-feline pan T-cell marker. An expression index (EI) was calculated by comparing mitogen-activated and non-activated PBMC. Based on side- and forward-scatter properties, flow cytometric analysis showed an increase in the number of larger, more granular "lymphoblasts" following concanavalin A (Con A) stimulation. The appearance of lymphoblasts was correlated with an increase in their surface expression of IL-2 receptors. Surface IL-2R expression, in Con A-stimulated PBMC, was detected at 16 h, peaked at 24-36 h, and began to decrease by 48 h. Characterization of the IL-2R expression should provide additional information on the health status of manatees, and the effect of their sub lethal exposure to brevetoxin.

The duration of in vitro stimulation with recall antigens determines the subset distribution of interferon-γ-producing lymphoid cells: A kinetic analysis using the Interferon-γ Secretion Assay™

Analyses of cellular immune responses during natural infections and following vaccination with established or candidate vaccines are becoming increasingly important and so are the research tools used to achieve this goal. During a recent evaluation of the analytical performance characteristics of one of these techniques, the interferon-gamma secretion assay, we noticed that following overnight incubation of PBMC with recall antigens (varicella-zoster antigen, Candida albicans antigen or hepatitis B surface antigen) NK cells are frequently the most predominant interferon-gamma-producing cell population. In this study, we monitored the subset distribution of interferon-gamma-producing cells following more extended in vitro culture periods and found that, irrespective of the antigen applied, the contribution of NK cells decreased whereas the importance of T cells and NKT cells rose. Analysis of the subset distribution showed that HBsAg stimulated CD4 cells predominantly whereas Candida antigen and varicella-zoster antigen were better inducers of CD8 responses. No correlation was found between the kinetics of total number of interferon-gamma-producing cells and the changes of concentrations of interferon-gamma in the culture supernatants. Interferon-gamma levels in culture supernatants correlated strongly with the kinetics of T(H) lymphocytes (CD3+, CD4+), CTL (CD3+, CD8+), and NKT cells (CD3+, CD56+). These observations lead us to conclude that methods that enumerate cytokine-secreting cells without determining their phenotype should be interpreted with great care and that an 'elispot' should not be directly considered as the footprint of a T lymphocyte.

Prior poliomyelitis—IvIg treatment reduces proinflammatory cytokine production

The postpolio syndrome (PPS) is characterized by progressive disabilities decades after recovery from the acute paralytic disease. There are reports on intrathecal inflammatory reactions in PPS, including increased expression of cytokines by cerebrospinal fluid (CSF) mononuclear cells (CSF-MC). This is potentially of relevance for the clinical condition. We here explored if cytokine expression in the CSF of PPS patients could be modulated by high-dose intravenous immunoglobulins (IvIg). The expression of TNF-alpha, IFN-gamma, IL-10 and IL-4 mRNAs was measured by real-time RT-PCR in CSF and peripheral blood mononuclear cells (PBMC) of 16 PPS patients before, and 6-8 weeks after IvIg treatment, and in 26 patients with noninflammatory other neurological diseases (OND). TNF-alpha, IFN-gamma and IL-10 CSF mRNA levels were elevated in samples from untreated persons with PPS compared to OND. Upon IvIg treatment, IFN-gamma and TNF-alpha mRNA levels were dramatically reduced, while IL-10 remained unchanged. Placebo-controlled studies are now warranted to evaluate if IvIg treatment also has any effects on the clinical manifestations of PPS.

Accurate and statistically verified quantification of relative mRNA abundances using SYBR Green I and real-time RT-PCR

Among the many methods currently available for quantifying mRNA transcript abundance, reverse transcription-polymerase chain reaction (RT-PCR) has proved to be the most sensitive. Recently, several protocols for real-time relative RT-PCR using the reporter dye SYBR Green I have appeared in the literature. In these methods, sample and control mRNA abundance is quantified relative to an internal reference RNA whose abundance is known not to change under the differing experimental conditions. We have developed new data analysis procedures for the two most promising of these methodologies and generated data appropriate to assess both the accuracy and precision of the two protocols. We demonstrate that while both methods produce results that are precise when 18S rRNA is used as an internal reference, only one of these methods produces consistently accurate results. We have used this latter system to show that mRNA abundances can be accurately measured and strongly correlate with cell surface protein and carbohydrate expression as assessed by flow cytometry under different conditions of B cell activation.

Optimal kinetics for quantification of antigen-induced cytokines in human peripheral blood mononuclear cells by real-time PCR and by ELISA

Real-time polymerase chain reaction (PCR) has recently been described as a new tool to measure and accurately quantify mRNA levels. In this study, we have applied this technique to evaluate cytokine mRNA synthesis induced by antigenic stimulation with purified protein derivative (PPD) or heparin-binding haemagglutinin (HBHA) in human peripheral blood mononuclear cells (PBMC) from Mycobacterium tuberculosis-infected individuals. Whereas PPD and HBHA optimally induced IL-2 mRNA after respectively 8 and 16 to 24 h of in vitro stimulation, longer in vitro stimulation times were necessary for optimal induction of interferon-gamma (IFN-gamma) mRNA, respectively 16 to 24 h for PPD and 24 to 96 h for HBHA. IL-13 mRNA was optimally induced by in vitro stimulation after 16-48 h for PPD and after 48 to 96 h for HBHA. Comparison of antigen-induced Th1 and Th2 cytokines appears, therefore, valuable only if both cytokine types are analysed at their optimal time point of production, which, for a given cytokine, may differ for each antigen tested. Results obtained by real-time PCR for IFN-gamma and IL-13 mRNA correlated well with those obtained by measuring the cytokine concentrations in cell culture supernatants, provided they were high enough to be detected. We conclude that real-time PCR can be successfully applied to the quantification of antigen-induced cytokine mRNA and to the evaluation of the Th1/Th2 balance, only if the kinetics of cytokine mRNA appearance are taken into account and evaluated for each cytokine measured and each antigen analysed.

PCR-based calibration curves for studies of quantitative gene expression in human monocytes: development and evaluation

BACKGROUND

Quantitative reverse transcription-PCR (RT-PCR) used to detect small changes in specific mRNA concentrations is often associated with poor reproducibility. Thus, there is a need for stringent quality control in each step of the protocol.

METHODS

Real-time PCR-based calibration curves for a target gene, tissue factor (TF), and a reference gene, beta-actin, generated from PCR amplicons were evaluated by running cDNA controls. In addition, the reverse transcription step was evaluated by running mRNA controls. Amplification efficiencies of calibrators and targets were determined. Variances within and between runs were estimated, and power statistics were applied to determine the concentration differences that could reliably be detected.

RESULTS

Within- and between-run variations (CVs) of cDNA controls (TF and beta-actin), extrapolated from reproducible calibration curves (CVs of slopes, 4.3% and 2.7%, respectively) were 4-10% (within) and 15-38% (between) using both daily and "grand mean" calibration curves. CVs for the beta-actin mRNA controls were 12% (within) and 19-28% (between). Estimates of each step's contribution to the total variation were as follows: CV(RT-PCR), 28%; CV(PCR), 15%; CV(RT), 23% (difference between CV(RT-PCR) and CV(PCR)). PCR efficiencies were as follows: beta-actin calibrator/target, 1.96/1.95; TF calibrator/target, 1.95/1.93. Duplicate measurements could detect a twofold concentration difference (power, 0.8).

CONCLUSIONS

Daily PCR calibration curves generated from PCR amplicons were reproducible, allowing the use of a grand mean calibration curve. The reverse transcription step contributes the most to the total variation. By determining a system's total variance, power analysis may be used to disclose differences that can be reliably detected at a specified power.

Cytokine mRNA profiles in bronchoalveolar cells of piglets experimentally infected in utero with porcine reproductive and respiratory syndrome virus: association of sustained expression of IFN-gamma and IL-10 after viral clearance

An experimental model was used to investigate mRNA cytokine profiles in bronchoalvolar cells (BALC) from piglets, infected in utero with porcine reproductive and respiratory syndrome virus (PRRSV). The BALC's were analyzed for the cytokines TNF-alpha, IFN-gamma, IL-8, IL-10, and IL-12(p40) by real-time TaqMan polymerase chain reaction in 2-, 4-, and 6-week-old piglets, respectively. High levels of IFN-gamma mRNA was detected in all piglets, while IL-10 was upregulated in 2-week-old piglets, was at normal levels in 4-week-old piglets, and elevated again in 6-week-old piglets. IL-12 was weakly elevated in all three age groups. Virus was reduced by 50% in 4-week-old piglets and cleared by 6 weeks of age. The sustained expression of IFNgamma and reduction of IL-10 production indicate an important role for these cytokines in immunity to PRRSV.

Delayed Cytokine mRNA Expression Kinetics after T-Lymphocyte Costimulation: A Quantitative Measure of the Efficacy of Cyclosporin A-based Immunosuppression

Background: Because cyclosporin A (CsA) and glucocorticoids inhibit the production of interleukin-2 (IL-2) and other cytokines, quantitative analysis of cytokine mRNA might constitute a pharmacodynamic measure for immunosuppressive drug effects. We investigated whether immunosuppressive drugs influence cytokine mRNA expression kinetics during T-cell costimulation.

Methods: We used a human whole blood assay to determine basal (unstimulated) IL-2, IL-4, and tumor necrosis factor-α (TNF-α) mRNA concentrations and expression kinetics after anti-CD3/anti-CD28 monoclonal antibody costimulation in kidney transplant recipients undergoing CsA-based immunosuppressive triple therapy and in healthy controls (ex vivo study I). The effect of CsA on IL-2 mRNA expression kinetics was also determined ex vivo in patients undergoing CsA monotherapy (ex vivo study II) and after in vitro addition of CsA.

Results: In ex vivo study I, basal TNF-α mRNA but not IL-2 and IL-4 mRNA was decreased in kidney transplant patients. We observed shifts in peak IL-2 and IL-4 (from 8 to 24 h) and TNF-α (from 4 to 8 h of costimulation) mRNA expression in kidney transplant patients after T-cell costimulation. In patients undergoing CsA monotherapy (ex vivo study II), the inhibitory effect of CsA was detectable as an individually delayed increase in IL-2 mRNA during costimulation. In vitro addition of CsA also induced a dose-independent displacement of IL-2 mRNA expression kinetics (i.e., a delay).

Conclusions: A delayed increase in cytokine mRNA expression during T-cell costimulation may represent a sensitive effect of immunosuppression. The single analysis of one absolute or peak mRNA value could be misleading. For prospective studies involving measurement of cytokine mRNA, we therefore suggest the parameter “area of cytokine mRNA expression over time”, which should include absolute cytokine mRNA values at two different time points of mRNA kinetics.