CD69 expression as an index of T-cell function: assay standardization, validation and use in monitoring immune recovery

Immunophenotyping of canine T cell activation and proliferation by combined protein and RNA flow cytometry

The limited availability of canine-reactive monoclonal antibodies restricts the analyses of immune cell subsets and their functions by flow cytometry. The PrimeFlow™ RNA Assay may serve as a potential solution to close this gap. Here we report a blood immunophenotyping method utilizing combined protein- and RNA-based flow cytometry to characterize canine T cell activation and proliferation within individual cells. In this assay, CD69 expression was detected by an RNA probe and CD25 and Ki67 were detected by antibodies. Canine peripheral blood mononuclear cells (PBMCs) were stimulated with three agents with different modes of action, anti-CD3/CD28 antibodies, phytohemagglutinin, or phorbol myristate acetate /ionomycin. Robust T cell activation (CD25+ and/or CD69+) and proliferation (Ki67+) were detected. Both CD69 and CD25 appear to be robust and sensitive T cell activation markers with early induction and low background expression. Upon stimulation, T cell proliferation occurred later than T cell activation and was associated with CD25 expression. This canine T cell activation and proliferation immunophenotyping method was evaluated in 5 independent experiments using PBMCs from 10 different beagle dogs with satisfactory assay performance. This method can greatly facilitate the evaluation of immune disease pathogenesis and immunotoxicity risk assessment in nonclinical drug development in canine.

Research progress on intestinal tissue-resident memory T cells in inflammatory bowel disease

Tissue-resident memory T (TRM) cells are a recently discovered subpopulation of memory T cells that reside in non-lymphoid tissues such as the intestine and skin and do not enter the bloodstream. The intestine encounters numerous pathogens daily. Intestinal mucosal immunity requires a balance between immune responses to pathogens and tolerance to food antigens and symbiotic microbiota. Therefore, intestinal TRM cells exhibit unique characteristics. In healthy intestines, TRM cells induce necessary inflammation to strengthen the intestinal barrier and inhibit bacterial translocation. During intestinal infections, TRM cells rapidly eliminate pathogens by proliferating, releasing cytokines, and recruiting other immune cells. Moreover, certain TRM cell subsets may have regulatory functions. The involvement of TRM cells in inflammatory bowel disease (IBD) is increasingly recognized as a critical factor. In IBD, the number of pro-inflammatory TRM cells increases, whereas the number of regulatory subgroups decreases. Additionally, the classic markers, CD69 and CD103, are not ideal for intestinal TRM cells. Here, we review the phenotype, development, maintenance, and function of intestinal TRM cells, as well as the latest findings in the context of IBD. Further understanding of the function of intestinal TRM cells and distinguishing their subgroups is crucial for developing therapeutic strategies to target these cells.

Perinatal derivatives: How to best validate their immunomodulatory functions

Perinatal tissues, mainly the placenta and umbilical cord, contain a variety of different somatic stem and progenitor cell types, including those of the hematopoietic system, multipotent mesenchymal stromal cells (MSCs), epithelial cells and amnion epithelial cells. Several of these perinatal derivatives (PnDs), as well as their secreted products, have been reported to exert immunomodulatory therapeutic and regenerative functions in a variety of pre-clinical disease models. Following experience with MSCs and their extracellular vesicle (EV) products, successful clinical translation of PnDs will require robust functional assays that are predictive for the relevant therapeutic potency. Using the examples of T cell and monocyte/macrophage assays, we here discuss several assay relevant parameters for assessing the immunomodulatory activities of PnDs. Furthermore, we highlight the need to correlate the in vitro assay results with preclinical or clinical outcomes in order to ensure valid predictions about the in vivo potency of therapeutic PnD cells/products in individual disease settings.

[Significance of evaluation of CD69 expression by peripheral blood lymphocytes for predicting pregnancy outcome in women with recurrent pregnancy loss]

The aim of this work was to characterize phenotypically peripheral blood T- and NK lymphocytes expressing an early marker of activation, CD69, and assess the significance of CD69 expression for predicting pregnancy outcome in women with idiopathic reccurent pregnancy loss (IRP) before and after immunocytotherapy (ICT). The study group consisted of 36 patients with IRP who became pregnant after pre-gestational allimmunization, in 30 patients the pregnancy was prolonged to the full term and ended with the birth of a viable baby, in 6 - it was terminated before 12 weeks of gestation. In the control group, 15 fertile women outside pregnancy and 11 women at 12 weeks of physiological pregnancy were examined. Assessment of the CD69 expression in women with prolonged pregnancy revealed the absence of significant differences with the control group in the content and proportion of activated lymphocytes (CD69+). In women with aborted pregnancy after pre-gestational ICT, an increase in the number of almost all analyzed lymphocyte subpopulations responding to the activation stimulus, with a clear tendency to increase the proportion of activated T- but not NK-lymphocytes was found. At 5-6 weeks, the proportion of activated lymphocytes among a subpopulation of cytotoxic T-lymphocytes (CD3+CD8+/CD3+CD8+CD69+) in these women was significantly higher than in women with prolonged pregnancy, which confirms the leading role of effector cytotoxic T-lymphocytes in rejection reactions. Thus, the studies showed the promise of evaluating the expression of the early activation marker CD69 as an additional laboratory criterion for the personable appointment of immunocytotherapy to women with a common reccurent pregnancy loss.

Safety assessment of a new nanoemulsion-based drug-delivery system reveals unexpected drug-free anticoagulant activity

Aim: A preclinical safety assessment of a novel nanoemulsion drug-delivery system, initially developed to improve the posology of efavirenz (EFV), was conducted with a specific focus on possible immunological and hematological complications. Materials & methods: Assessment of common acute toxicities, such as complement activation and cytokine secretion, was performed using validated assays known to have good correlation with in vivo end points. Results & conclusion: Compared with a standard aqueous solution of EFV, the EFV nanoemulsion showed no significant effect on immune cell function or phenotype. Prolongation of activated partial thromboplastin time was observed for EFV-loaded nanoemulsions (88% at 4 μg/ml) as well as unloaded nanoemulsions (52%) highlighting the potential for drug-free anticoagulant activity and warranting further investigation of the mechanism and utility of these materials.

The protein tyrosine kinase SYK regulates the alternative p38 activation in liver during acute liver inflammation

Two distinct p38 signaling pathways, classical and alternative, have been identified to regulate inflammatory responses in host defense and disease development. The role of alternative p38 activation in liver inflammation is elusive, while classical p38 signaling in hepatocytes plays a role in regulating the induction of cell death in autoimmune-mediated acute liver injury. In this study, we found that a mutation of alternative p38 in mice augmented the severity of acute liver inflammation. Moreover, TNF-induced hepatocyte death was augmented by a mutation of alternative p38, suggesting that alternative p38 signaling in hepatocytes contributed more significantly to the pathology of acute liver injury. Furthermore, SYK-Vav-1 signaling regulates alternative p38 activation and the downregulation of cell death in hepatocytes. Therefore, it is suggested that alternative p38 signaling in the liver plays a critical role in the induction and subsequent pathological changes of acute liver injury. Collectively, our results imply that p38 signaling in hepatocytes plays a crucial role to prevent excessive liver injury by regulating the induction of cell death and inflammation.

A Novel Bacterium-Like Particle Vaccine Displaying the MERS-CoV Receptor-Binding Domain Induces Specific Mucosal and Systemic Immune Responses in Mice

Middle East respiratory syndrome coronavirus (MERS-CoV), a new coronavirus that has been causing severe and fatal acute respiratory illnesses in humans since its outbreak in 2012, has raised public fear worldwide. The development of prophylactics and therapeutics is urgently needed to prevent and control MERS-CoV infections. In this study, a bacterium (Lactococcus lactis)-like particle (BLP) vaccine displaying the MERS-CoV receptor-binding domain (RBD) was developed, and gram-positive enhancer matrix (GEM) particles were used as substrates to externally bind to the MERS-CoV RBD through a protein anchor (PA). The designs included different numbers of lysin motif (LysM) repeats in the PAs linked by linkers (RBD-linker-PA2 (RLP2), RBD-linker-PA3 (RLP3) and RBD-PA3 (RP3)), and three LysM repeats and a linker in the fusion proteins increased the binding activity to the RBD. The specific immune responses were tested by intranasally immunizing mice with RLP3-GEM with or without the adjuvant GEL01. The results showed that GEL01-adjuvanted RLP3-GEM increased the systemic humoral, cellular and local mucosal immune responses in the mouse model, especially in the intestinal tract. The above results indicate that the MERS-CoV BLP product has the potential to be developed into a promising mucosal candidate vaccine to protect against MERS-CoV infections.

Deep Profiling of the CD8+ T-cell Compartment Identifies Activated Cell Subsets and Multifunctional Responses Associated With Control of Cytomegalovirus Viremia

BACKGROUND

Human cytomegalovirus (HCMV) is a common opportunistic pathogen in transplant recipients. Patterns of viremia and reactivation are influenced by the host immune response, including CD8 T cells. However, the cellular deficits or phenotypic differences that account for differential outcomes during HCMV viremia are incompletely understood.

METHODS

Peripheral blood mononuclear cells were collected from 20 transplant recipients (10 viremia controllers and 10 noncontrollers) at onset of HCMV viremia and 4 weeks postonset. We used mass cytometry to perform in-depth characterization of cell surface and intracellular CD8 T cell markers and to compare frequencies of these cells between groups.

RESULTS

Deep profiling identified 2 central memory T cell subsets at onset and 5 terminally differentiated memory T (TEMRA) cell subsets at 4 weeks that were associated with control of HCMV viremia, in addition to 6 TEMRA subsets at onset and 4 weeks associated with relapsing or remitting HCMV viremia. In general, CD8 T-cell clusters associated with poorly controlled HCMV viremia lacked markers of activation or terminal differentiation including CD38, CD69, CD25, CD57, and HLA-DR. We also measured the production of 8 HCMV-specific effector molecules (TNFα, IFNγ, interleukin 2, granzyme B, perforin, macrophage inflammatory protein 1β, interleukin 10, and CD107a) in CD8 T cells. Viremia controllers had greater diversity of HCMV-specific multifunctional responses at both time points, including significantly higher frequencies of HCMV-specific TNFαIFNγ CD8 T cells at onset. These multifunctional cells had a phenotype consistent with activated TEM/TEMRA cells.

CONCLUSIONS

Uncontrolled CMV viremia is associated with specific clusters of memory T-cell subsets and lower frequencies of HCMV-specific multifunctional CD8 T cells.

Aryl hydrocarbon receptor activation modulates γδ intestinal intraepithelial lymphocytes and protects against ischemia/reperfusion injury in the murine small intestine

The pathogenesis of intestinal ischemia/reperfusion (I/R) is associated with dysregulation of the intestinal immune system. The aryl hydrocarbon receptor (AhR), a receptor expressed in gamma‑delta (γδ) intraepithelial lymphocytes (IELs), is thought to regulate inflammation in the bowel. γδIELs are a key immunologic compartment with a capacity to modulate immune responses. In the present study, the function of the AhR in γδIELs in a mouse model of intestinal I/R injury was investigated to determine whether the AhR attenuates intestinal injury induced by intestinal I/R. Mice were assigned to three groups: sham, I/R and I/R+6‑formylindolo(3,2‑b)carbazole (FICZ). The sham group received no ischemia treatment, whereas the I/R and I/R+FICZ groups underwent upper mesenteric vessel ischemia for 30 min. The I/R group was injected intraperitoneally with 0.3 ml saline and the I/R+FICZ group was administered 1 µg of FICZ before a subsequent 6 h reperfusion. Then, the mice were sacrificed and the entire small intestinal tissues were collected for histologic examination. The phenotype and apoptosis of γδIELs and activation of CD4+ and CD8+ IELs were examined using flow cytometry. The cytokine mRNA and anti‑apoptosis gene expression in IELs were measured by qPCR. FICZ increased the γδIEL population and anti‑apoptosis genes in the γδIELs. FICZ reduced the percentage of activated CD4+ and CD8+ subpopulations and the expression of pro‑inflammatory mediator genes in IELs. FICZ inhibited inflammation in the gastrointestinal tract of mice with I/R injury. These results suggest that the AhR plays an important role in protecting the small intestine from I/R and increasing the γδIEL population by decreasing apoptosis of γδIELs.

Macrophage-derived insulin-like growth factor-1 affects influenza vaccine efficacy through the regulation of immune cell homeostasis

The level of antibody production induced by a vaccine involves a variety of host factors. One of these, insulin-like growth factor-1 (IGF-1), plays an important role in lymphocyte maturation and antibody expression. Here, we investigated the role of macrophage-derived IGF-1 in the induction of influenza vaccine-specific antibodies using macrophage-derived IGF-1 gene knockout (MIKO) mice. The titers of vaccine-specific total immunoglobulin G (IgG) and IgG1 after immunization were about two- to fourfold lower in MIKO mice than in WT mice. Moreover, MIKO mice showed a relatively weak booster effect of repeated immunization. In contrast, antigen-nonspecific total IgG was about threefold higher in MIKO mice than in WT mice. After viral challenge, the viral titer and the pathological damage in lungs of MIKO mice were higher than those in WT mice despite vaccination. Interestingly, the proportions of proinflammatory immune cells including M1 macrophages, Th1 and Th17 cells was higher in unvaccinated MIKO mice than in unvaccinated WT mice. This suggests that nonspecific activation of immune cells may paradoxically impair the response to the vaccine. In addition, although the proportions of T follicular helper (Tfh) cells and GL-7⁺ germinal center (GC) B cells were higher in MIKO mice than in WT mice, the population of CD138⁺B220⁺ antibody-secreting plasmablasts was lower in MIKO mice, which may be a cause of the low influenza-specific antibody titer in MIKO mice. Taken together, these results suggest that macrophage-derived IGF-1 might play an important role in the vaccine-triggered immune response by regulating immune cell homeostasis.

Immunoglobulin and B-cell disturbances in patients with chronic idiopathic neutropenia

Chronic idiopathic neutropenia (CIN) is a granulocytic disorder associated with presence of activated, myelosuppressive T-lymphocytes. In the present study we have evaluated constituents of humoral immunity in CIN patients (n=48) compared to healthy controls (n=52). CIN patients displayed lower serum IgG levels due to a reduction in IgG1, IgG3, IgG4 but not IgG2, lower IgA and increased IgM levels compared to controls. The proportion of CD19⁺ cells did not differ between patients and controls; however the proportion of the naïve IgD⁺/CD27^- B-cells was increased and the proportion of class-switched memory IgD^-/CD27⁺ B-cells was decreased in the patients. The percentage of CD40⁺ B-cells did not differ between patients and controls and no aberrations in the CD40-meadiated signal transduction pathway or in CD40-gene polymorphisms were identified. These data provide further evidence that immune disturbances are associated with the pathophysiology of CIN and point out for the first time the implication of the B-cell system.

Immunogenicity of oncolytic vaccinia viruses JX-GFP and TG6002 in a human melanoma in vitro model: studying immunogenic cell death, dendritic cell maturation and interaction with cytotoxic T lymphocytes

Oncolytic virotherapy is an emerging immunotherapeutic modality for cancer treatment. Oncolytic viruses with genetic modifications can further enhance the oncolytic effects on tumor cells and stimulate antitumor immunity. The oncolytic vaccinia viruses JX-594-GFP+/hGM-CSF (JX-GFP) and TG6002 are genetically modified by secreting granulocyte-macrophage colony-stimulating factor (GM-CSF) or transforming 5-fluorocytosine (5-FC) into 5-fluorouracil (5-FU). We compared their properties to kill tumor cells and induce an immunogenic type of cell death in a human melanoma cell model using SK29-MEL melanoma cells. Their influence on human immune cells, specifically regarding the activation of dendritic cells (DCs) and the interaction with the autologous cytotoxic T lymphocyte (CTL) clone, was investigated. Melanoma cells were infected with either JX-GFP or TG6002 alone or in combination with 5-FC and 5-FU. The influence of viral infection on cell viability followed a time- and multiplicity of infection dependent manner. Combination of virus treatment with 5-FU resulted in stronger reduction of cell viability. TG6002 in combination with 5-FC did not significantly strengthen the reduction of cell viability in this setting. Expression of calreticulin and high mobility group 1 protein (HMGB1), markers of immunogenic cell death (ICD), could be detected after viral infection. Accordingly, DC maturation was noted after viral oncolysis. DCs presented stronger expression of activation and maturation markers. The autologous CTL clone IVSB expressed the activation marker CD69, but viral treatment failed to enhance cytotoxicity marker. In summary, vaccinia viruses JX-GFP and TG6002 lyse melanoma cells and induce additional immunostimulatory effects to promote antitumor immune response. Further investigation in vivo is needed to consolidate the data.

Splenic Damage during SIV Infection: Role of T-Cell Depletion and Macrophage Polarization and Infection

The effects of HIV infection on spleen and its cellular subsets have not been fully characterized, particularly for macrophages in which diverse populations exist. We used an accelerated SIV-infected macaque model to examine longitudinal effects on T-cell and macrophage populations and their susceptibilities to infection. Substantial lymphoid depletion occurred, characterized by follicular burn out and a loss of CD3 T lymphocytes, which was associated with cellular activation and transient dysregulations in CD4/CD8 ratios and memory effector populations. In contrast, the loss of CD68 and CD163(+)CD68(+) macrophages and increase in CD163 cells was irreversible, which began during acute infection and persisted until terminal disease. Mac387 macrophages and monocytes were transiently recruited into spleen, but were not sufficient to mitigate the changes in macrophage subsets. Type I interferon, M2 polarizing genes, and chemokine-chemokine receptor signaling were up-regulated in spleen and drove macrophage alterations. SIV-infected T cells were numerous within the white pulp during acute infection, but were rarely observed thereafter. CD68, CD163, and Mac387 macrophages were highly infected, which primarily occurred in the red pulp independent of T cells. Few macrophages underwent apoptosis, indicating that they are a long-lasting target for HIV/SIV. Our results identify macrophages as an important contributor to HIV/SIV infection in spleen and in promoting morphologic changes through the loss of specific macrophage subsets that mediate splenic organization.

Lymphocyte surface molecules as immune activation biomarkers

Immunosuppression is mandatory after solid organ transplantation between HLA mismatched individuals. It is a lifelong therapy that needs to be closely monitored to avoid under- and over-immunosuppression. For many drugs, pharmacokinetic monitoring has been proven to be beneficial. However, the therapeutic ranges are statistically derived surrogate markers for the effects that cannot predict the individual response of single patients. Better tailored immunosuppression biomarkers are needed that indicate immune activation. T cells are critically involved in organ rejection, and the means to assess their activation state may be promising to individualize immunosuppressive therapies. Activated T cells can be monitored with flow cytometry based on surface molecules that are typically up regulated or with molecules that are cleaved off the cell surface. Among these molecules are the interleukin-2 receptor (CD25); transferrin receptor (CD71); the T cell co-stimulatory molecules CD28, CD69, and CD154 and sCD30, which is a member of the TNF-alpha family. The effect of immunosuppressive drugs on T cell activation can be recorded with indirect cell function assays or by directly monitoring activated T cells in whole blood. Soluble proteins can be measured with immunoassays. This review provides a summary of the experimental and clinical studies investigating the potential of surface molecules as a tool for immune monitoring. It critically discusses the obstacles and shortcomings from an analytical and diagnostic perspective that are currently preventing their use in multicenter trials and clinical routine monitoring of transplant patients.

Molecular Mechanisms of Interaction Between Human Immune Cells and Far Eastern Tick-Borne Encephalitis Virus Strains

Although studies have established that immune mechanisms are important in controlling tick-borne encephalitis virus (TBEV) infection, the interactions of different TBEV strains with cells of innate and adaptive immunity are not well understood. In this study, the ability of two Far Eastern subtype TBEV strains (Dal'negorsk and Primorye-183) with various degrees of pathogenicity for humans to modulate the expression of membrane molecules differently on human immune cells were investigated using a whole-blood flow cytometry-based assay. The whole-blood samples (from 10 healthy donors) were infected with TBEV strains and analyzed for the virus binding to the blood cells, as well as expression of adhesion (CD11b and ICAM-1) and activation (CD69, CD25, CD95) molecules on the surfaces of monocytes, granulocytes, natural killer (NK) cells, and T-lymphocytes (CD4+, CD8+) at selected times (3, 6, and 24 h post-infection). It was found that the highly pathogenic Dal'negorsk strain penetrated rapidly and was actively replicated in the blood cells, inducing downregulation of CD11b, ICAM-1, and CD69 on monocytes and a significant decrease of NK cells expressing CD69, CD25, CD95, and CD8 T-lymphocytes expressing CD69 compared with the mock-infected cells. The nonpathogenic Primorye-183 strain penetrated slowly and was replicated in the blood cells, but caused a significant increase in the adhesion and activation of molecule expression to trigger innate defense mechanisms and enable the rapid elimination of the virus from the organism. Thus, TBEV-induced activation or suppression of adhesion and activation receptors expression form an essential part of fundamental virus properties, that is, virulence and pathogenicity.

Immunopotentiator-Loaded Polymeric Microparticles as Robust Adjuvant to Improve Vaccine Efficacy

PURPOSE

Adjuvants are required to ensure the efficacy of subunit vaccines. Incorporating molecular immunopotentiators within particles could overcome drawbacks of molecular adjuvants (such as solubility and toxicity), and improve adjuvanticity of particles, achieving stronger adjuvant activity. Aim of this study is to evaluate the adjuvanticity of immunopotentiator-loaded polymeric particles for subunit vaccine.

METHODS

PLGA microparticles (PMPs) and imiquimod (TLR-7 ligand)-loaded PLGA microparticles (IPMPs) were prepared by SPG premix membrane emulsification. In vitro and in vivo studies were performed to their adjuvant activity, using ovalbumin and H5N1 influenza split vaccine as antigens.

RESULTS

Incorporating imiquimod into microparticles significantly improved the efficacy of PLGA microparticles in activating BMDCs and pMΦs, and antigen uptake by pMΦs was also promoted. IPMPs showed stronger adjuvanticity to augment OVA-specific immune responses than PMPs. IgG subclass profiles and cytokine secretion levels by splenocytes indicated that IPMPs elicited more Th1-polarized immune response, compared to PMPs. In vivo study using H5N1 influenza split vaccine as antigen also confirmed the effects of IPMPs on antigen-specific cellular immunity.

CONCLUSIONS

Considering adjuvanticity and safety profiles (PLGA and IMQ, both approved by FDA), we conclude that IMQ-loaded PLGA microparticles are promising robust adjuvant for subunit vaccines.

A rationally designed combined treatment with an alphavirus-based cancer vaccine, sunitinib and low-dose tumor irradiation completely blocks tumor development

The clinical efficacy of therapeutic cancer vaccines remains limited. For effective immunotherapeutic responses in cancer patients, multimodal approaches capable of both inducing antitumor immune responses and bypassing tumor-mediated immune escape seem essential. Here, we report on a combination therapy comprising sunitinib (40 mg/kg), single low-dose (14 Gy) tumor irradiation and immunization with a therapeutic cancer vaccine based on a Semliki Forest virus vector encoding the oncoproteins E6 and E7 of human papillomavirus (SFVeE6,7). We previously demonstrated that either low-dose irradiation or sunitinib in single combination with SFVeE6,7 immunizations enhanced the intratumoral ratio of antitumor effector cells to myeloid-derived suppressor cells (MDSCs). On the basis of these results we designed a triple treatment combinatorial regimen. The trimodal sunitinib, low-dose irradiation and SFVeE6,7 immunization therapy resulted in stronger intratumoral MDSC depletion than sunitinib alone. Concomitantly, the highest levels of intratumoral E7-specific CD8⁺ T cells were attained after triple treatment. Approximately 75% of these cells were positive for the early activation marker CD69. The combination of sunitinib, low-dose tumor irradiation and SFVeE6,7 immunization dramatically changed the intratumoral immune compartment. Whereas control tumors contained 0.02 E7-specific CD8⁺ T cells per MDSC, triple treatment tumors contained more than 200 E7-specific CD8⁺ T cells per MDSC, a 10,000-fold increased ratio. As a result, the triple treatment strongly enhanced the immunotherapeutic antitumor effect, blocking tumor development altogether and leading to 100% tumor-free survival of tumor-bearing mice. This study demonstrates that this multimodal approach elicits superior antitumor effects and should be considered for clinical applications.

Sunitinib depletes myeloid-derived suppressor cells and synergizes with a cancer vaccine to enhance antigen-specific immune responses and tumor eradication

The high efficacy of therapeutic cancer vaccines in preclinical studies has yet to be fully achieved in clinical trials. Tumor immune suppression is a critical factor that hampers the desired antitumor effect. Here, we analyzed the combined effect of a cancer vaccine and the receptor tyrosine kinase inhibitor sunitinib. Sunitinib was administered intraperitoneally, alone or in combination with intramuscular immunization using a viral vector based cancer vaccine composed of Semliki Forest virus replicon particles and encoding the oncoproteins E6 and E7 (SFVeE6,7) of human papilloma virus (HPV). We first demonstrated that treatment of tumor-bearing mice with sunitinib alone dose-dependently depleted myeloid-derived suppressor cells (MDSCs) in the tumor, spleen and in circulation. Concomitantly, the number of CD8⁺ T cells increased 2-fold and, on the basis of CD69 expression, their activation status was greatly enhanced. The intrinsic immunosuppressive activity of residual MDSCs after sunitinib treatment was not changed in a dose-dependent fashion. We next combined sunitinib treatment with SFVeE6,7 immunization. This combined treatment resulted in a 1.5- and 3-fold increase of E7-specific cytotoxic T lymphocytes (CTLs) present within the circulation and tumor, respectively, as compared to immunization only. The ratio of E7-specific CTLs to MDSCs in blood thereby increased 10- to 20-fold and in tumors up to 12.5-fold. As a result, the combined treatment strongly enhanced the antitumor effect of the cancer vaccine. This study demonstrates that sunitinib creates a favorable microenvironment depleted of MDSCs and acts synergistically with a cancer vaccine resulting in enhanced levels of active tumor-antigen specific CTLs, thus changing the balance in favor of antitumor immunity.

Natural indoles, indole-3-carbinol and 3,3'-diindolymethane, inhibit T cell activation by staphylococcal enterotoxin B through epigenetic regulation involving HDAC expression

Staphylococcal enterotoxin B (SEB) is a potent exotoxin produced by the Staphylococcus aureus. This toxin is classified as a superantigen because of its ability to directly bind with MHC-II class molecules followed by activation of a large proportion of T cells bearing specific Vβ-T cell receptors. Commonly associated with classic food poisoning, SEB has also been shown to induce toxic shock syndrome, and is also considered to be a potential biological warfare agent because it is easily aerosolized. In the present study, we assessed the ability of indole-3-carbinol (I3C) and one of its byproducts, 3,3'-diindolylmethane (DIM), found in cruciferous vegetables, to counteract the effects of SEB-induced activation of T cells in mice. Both I3C and DIM were found to decrease the activation, proliferation, and cytokine production by SEB-activated Vβ8(+) T cells in vitro and in vivo. Interestingly, inhibitors of histone deacetylase class I (HDAC-I), but not class II (HDAC-II), showed significant decrease in SEB-induced T cell activation and cytokine production, thereby suggesting that epigenetic modulation plays a critical role in the regulation of SEB-induced inflammation. In addition, I3C and DIM caused a decrease in HDAC-I but not HDAC-II in SEB-activated T cells, thereby suggesting that I3C and DIM may inhibit SEB-mediated T cell activation by acting as HDAC-I inhibitors. These studies not only suggest for the first time that plant-derived indoles are potent suppressors of SEB-induced T cell activation and cytokine storm but also that they may mediate these effects by acting as HDAC inhibitors.

Fine tuning and efficient T cell activation with stimulatory aCD3 nanoarrays

Anti-CD3 (aCD3) nanoarrays fabricated by self-assembled nanopatterning combined with site-directed protein immobilization techniques represent a novel T cell stimulatory platform that allows tight control over ligand orientation and surface density. Here, we show that activation of primary human CD4+ T cells, defined by CD69 upregulation, IL-2 production and cell proliferation, correlates with aCD3 density on nanoarrays. Immobilization of aCD3 through nanopatterning had two effects: cell activation was significantly higher on these surfaces than on aCD3-coated plastics and allowed unprecedented fine-tuning of T cell response.

Comparison of PLA microparticles and alum as adjuvants for H5N1 influenza split vaccine: adjuvanticity evaluation and preliminary action mode analysis

PURPOSE

To compare the adjuvanticity of polymeric particles (new-generation adjuvant) and alum (the traditional and FDA-approved adjuvant) for H5N1 influenza split vaccine, and to investigate respective action mode.

METHODS

Vaccine formulations were prepared by incubating lyophilized poly(lactic acid) (PLA) microparticles or alum within antigen solution. Antigen-specific immune responses in mice were evaluated using ELISA, ELISpot, and flow cytometry assay. Adjuvants' action modes were investigated by determining antigen persistence at injection sites, local inflammation response, antigen transport into draining lymph node, and activation of DCs in secondary lymphoid organs (SLOs).

RESULTS

Alum promoted antigen-specific humoral immune response. PLA microparticles augmented both humoral immune response and cell-mediated-immunity which might enhance cross-protection of influenza vaccine. With regard to action mode, alum adjuvant functions by improving antigen persistence at injection sites, inducing severe local inflammation, slightly improving antigen transport into draining lymph nodes, and improving the expression of MHC II on DCs in SLOs. PLA microparticles function by slightly improving antigen transport into draining lymph nodes, and promoting the expression of both MHC molecules and co-stimulatory molecules on DCs in SLOs.

CONCLUSIONS

Considering the adjuvanticity and side effects (local inflammation) of both adjuvants, we conclude that PLA microparticles are promising alternative adjuvant for H5N1 influenza split vaccine.

High non-specific T lymphocyte response to the adjuvanted H1N1 vaccine in comparison with the H1N1/H3N2/B-Brisbane vaccine without adjuvant

Shortly after the report of pandemic 2009 influenza A (H1N1), vaccine manufacturers, in conjunction with public agencies, started developing a H1N1 vaccine. In 2009, various approaches were implemented around the globe. The United States and Australia finally approved only non-adjuvanted H1N1 influenza vaccines, whereas Canada and the EU also approved adjuvanted vaccines. In 2010, seasonal influenza vaccine without adjuvant was again widely accepted in both hemispheres. The addition of adjuvant to the vaccine enhances the immunogenity of the vaccine in the presence of a relatively low amount of antigen. However, it might also induce undesirable non-specific immune response. For this reason, we conducted a prospective observational study to monitor T cell absolute count and H1N1-specific immunogenicity after 2009 and 2010 immunization. Fourteen healthy volunteers received the monovalent H1N1 AS03 adjuvanted influenza vaccine (3.5 μg of H1N1 and squalene-based adjuvant) in October 2009. The immunization was associated with a significant increase in T lymphocyte absolute count (P < 0.0001), reaching abnormal values in 57% of subjects. During this period, none of the subject showed any manifestation of severe viral infection or inflammation. Acute infection by CMV or EBV viruses was also excluded. In October 2010, the same subjects received a seasonal non-adjuvanted influenza vaccine (15 μg of each: H1N1, H3N2, and B-Brisbane). However, after 2010 immunization, no change in T lymphocyte absolute count was observed. H1N1-induced immunogenicity was good for both vaccines. Our results suggest a pronounced non-specific T cell response after AS03-adjuvanted 2009 H1N1 vaccination.

PI3Kδ is essential for tumor clearance mediated by cytotoxic T lymphocytes

Background

PI3Kδ is a lipid kinase of the phosphoinositide 3-kinase class 1A family and involved in early signaling events of leukocytes regulating proliferation, differentiation and survival. Currently, several inhibitors of PI3Kδ are under investigation for the treatment of hematopoietic malignancies. In contrast to the beneficial effect of inhibiting PI3Kδ in tumor cells, several studies reported the requirement of PI3Kδ for the function of immune cells, such as natural killer and T helper cells. Cytotoxic T lymphocytes (CTLs) are essential for tumor surveillance. The scope of this study is to clarify the potential impact of PI3Kδ inhibition on the function of CTLs with emphasis on tumor surveillance.

Principal Findings

PI3Kδ-deficient mice develop significantly bigger tumors when challenged with MC38 colon adenocarcinoma cells. This defect is accounted for by the fact that PI3Kδ controls the secretory perforin-granzyme pathway as well as the death-receptor pathway of CTL-mediated cytotoxicity, leading to severely diminished cytotoxicity against target cells in vitro and in vivo in the absence of PI3Kδ expression. PI3Kδ-deficient CTLs express low mRNA levels of important components of the cytotoxic machinery, e.g. prf1, grzmA, grzmB, fasl and trail. Accordingly, PI3Kδ-deficient tumor-infiltrating CTLs display a phenotype reminiscent of naïve T cells (CD69^lowCD62L^high). In addition, electrophysiological capacitance measurements confirmed a fundamental degranulation defect of PI3Kδ−/− CTLs.

Conclusion

Our results demonstrate that CTL-mediated tumor surveillance is severely impaired in the absence of PI3Kδ and predict that impaired immunosurveillance may limit the effectiveness of PI3Kδ inhibitors in long-term treatment.

Harnessing oncolytic virus-mediated antitumor immunity in an infected cell vaccine

Treatment of permissive tumors with the oncolytic virus (OV) VSV-Δ51 leads to a robust antitumor T-cell response, which contributes to efficacy; however, many tumors are not permissive to in vivo treatment with VSV-Δ51. In an attempt to channel the immune stimulatory properties of VSV-Δ51 and broaden the scope of tumors that can be treated by an OV, we have developed a potent oncolytic vaccine platform, consisting of tumor cells infected with VSV-Δ51. We demonstrate that prophylactic immunization with this infected cell vaccine (ICV) protected mice from subsequent tumor challenge, and expression of granulocyte-monocyte colony stimulating factor (GM-CSF) by the virus (VSVgm-ICV) increased efficacy. Immunization with VSVgm-ICV in the VSV-resistant B16-F10 model induced maturation of dendritic and natural killer (NK) cell populations. The challenge tumor is rapidly infiltrated by a large number of interferon γ (IFNγ)-producing T and NK cells. Finally, we demonstrate that this approach is robust enough to control the growth of established tumors. This strategy is broadly applicable because of VSV's extremely broad tropism, allowing nearly all cell types to be infected at high multiplicities of infection in vitro, where the virus replication kinetics outpace the cellular IFN response. It is also personalized to the unique tumor antigen(s) displayed by the cancer cell.

Human CD4+ lymphocytes for antigen quantification: characterization using conventional flow cytometry and mass cytometry

To transform the linear fluorescence intensity scale obtained with fluorescent microspheres to an antibody bound per cell (ABC) scale, a biological cell reference material is needed. Optimally, this material should have a reproducible and tight ABC value for the expression of a known clinical reference biomarker. In this study, we characterized commercially available cryopreserved peripheral blood mononuclear cells (PBMCs) and two lyophilized PBMC preparations, Cyto-Trol and PBMC-National Institute for Biological Standard and Control (NIBSC) relative to freshly prepared PBMC and whole blood samples. It was found that the ABC values for CD4 expression on cryopreserved PBMC were consistent with those of freshly obtained PBMC and whole blood samples. By comparison, the ABC value for CD4 expression on Cyto-Trol is lower and the value on PBMC-NIBSC is much lower than those of freshly prepared cell samples using both conventional flow cytometry and CyTOF™ mass cytometry. By performing simultaneous surface and intracellular staining measurements on these two cell samples, we found that both cell membranes are mostly intact. Moreover, CD4(+) cell diameters from both lyophilized cell preparations are smaller than those of PBMC and whole blood. This could result in steric interference in antibody binding to the lyophilized cells. Further investigation of the fixation effect on the detected CD4 expression suggests that the very low ABC value obtained for CD4(+) cells from lyophilized PBMC-NIBSC is largely due to paraformaldehyde fixation; this significantly decreases available antibody binding sites. This study provides confirmation that the results obtained from the newly developed mass cytometry are directly comparable to the results from conventional flow cytometry when both methods are standardized using the same ABC approach.

The regulation of CD4+ T cell immune responses toward Th2 cell development by prostaglandin E2

As an important immune mediator, PGE2 plays an important role in the immune tolerance, autoimmune diseases, immune regulation and tumor immunotolerance. PGE2 is considered to be a promising candidate for the control of the immune diseases. To further understand the immuno-modulating effects of PGE2 on CD4+ T cells, in vitro investigation was conducted in the present study. The results showed that PGE2 inhibited the proliferation of T cells in vitro in a dose-dependent manner. Gene expression profiling showed that 1716 genes were down regulated and 73 genes were up regulated with a change of 1.5 fold. Several signal transduction pathways were involved, such as TNF-α and NF-kB signaling pathway, T cell receptor signaling pathway, IL-2 signaling pathway, and MAPK pathway. The results showed that PGE2 inhibited IFN-γ, TNF-α and IL-4 production by CD4+ T cells 24h after cell culture. A comparison between IFN-γ and IL-4 production showed that PGE2 enhanced the relative ratio of IL-4 to IFN-γ in CD4+ T cells culture, and regulated CD4+ T cells toward Th2 cell development. The results of the present study indicated that PGE2 has the potential to treat Th1-mediated inflammatory diseases by regulating CD4+ T cells toward Th2 cell immune response.

Quantitative proteomics analysis of the nuclear fraction of human CD4+ cells in the early phases of IL-4-induced Th2 differentiation

We used stable isotope labeling with 4-plex iTRAQ (isobaric tags for relative and absolute quantification) reagents and LC-MS/MS to investigate proteomic changes in the nucleus of activated human CD4⁺ cells during the early stages of Th2 cell differentiation. The effects of IL-4 stimulation upon activated naïve CD4⁺ cells were measured in the nuclear fractions from 6 and 24 h in three biological replicates, each using pooled cord blood samples derived from seven or more individuals. In these analyses, in the order of 800 proteins were detected with two or more peptides and quantified in three biological replicates. In addition to consistent differences observed with the nuclear localization/expression of established human Th2 and Th1 markers, there were changes that suggested the involvement of several proteins either only recently reported or otherwise not known in this context. These included SATB1 and among the novel changes detected and validated an IL-4-induced increase in the level of YB1. This unique data set from human cord blood CD4⁺ T cells details an extensive list of protein determinations that compares with and complements previous data determined from the Jurkat cell nucleus.

Selective effects of Lactobacillus casei Shirota on T cell activation, natural killer cell activity and cytokine production

Modulation of host immunity is an important potential mechanism by which probiotics confer health benefits. This study was designed to investigate the effects of a probiotic strain, Lactobacillus casei Shirota (LcS), on immune function using human peripheral blood mononuclear cells (PBMC) in vitro. In addition, the role of monocytes in LcS-induced immunity was also explored. LcS promoted natural killer (NK) cell activity and preferentially induced expression of CD69 and CD25 on CD8(+) and CD56(+) subsets in the absence of any other stimulus. LcS also induced production of interleukin (IL)-1beta, IL-6, tumour necrosis factor (TNF)-alpha, IL-12 and IL-10 in the absence of lipopolysaccharide (LPS). In the presence of LPS, LcS enhanced IL-1beta production but inhibited LPS-induced IL-10 and IL-6 production, and had no further effect on TNF-alpha and IL-12 production. Monocyte depletion reduced significantly the impact of LcS on lymphocyte activation, cytokine production and natural killer (NK) cell activity. In conclusion, LcS activated cytotoxic lymphocytes preferentially in both the innate and specific immune systems, which suggests that LcS could potentiate the destruction of infected cells in the body. LcS also induced both proinflammatory and anti-inflammatory cytokine production in the absence of LPS, but in some cases inhibited LPS-induced cytokine production. Monocytes play an important role in LcS-induced immunological responses.

Validation of a quantitative flow cytometer assay for monitoring HER-2/neu expression level in cell-based cancer immunotherapy products

GVAX immunotherapy for prostate cancer is comprised of two genetically modified prostate cancer cell lines, CG1940 and CG8711, engineered to secrete granulocyte macrophage-colony-stimulating factor. As part of the matrix of potency assays, CG1940 and CG8711 are tested for the expression level of cell surface HER-2/neu using a quantitative flow cytometer assay. This assay reports the antibody binding capacity value of the cells as a measure of HER-2/neu expression using cells immediately after thawing from cryogenic storage. With optimized cell handling and staining procedure and appropriate system suitability controls, the assay was validated as a quantitative assay. The validation results showed that assay accuracy, specificity, precision, linearity, and range were suitable for the intended use of ensuring lot-to-lot consistency of HER-2/neu expression. Assay robustness was demonstrated using design of experiments that evaluated critical assay parameters. Finally, the assay was successfully transferred to a current good manufacturing practice Quality Control laboratory in a separate facility. Since the overall precision of this assay is better than that of ELISA methods and it can be performed with ease and high throughput, quantitative flow cytometer-based assays may be an appropriate immunological assay platform for Quality Control laboratories for characterization and release of cell-based therapies.

Effects of FR-91 on immune cells from healthy individuals and from patients with non-Hodgkin lymphoma

The immune system is subject to destruction and dysfunction as a result of attacks by pathogenic and environmental agents. In addition, many clinical situations exist in which it is desirable to stimulate or suppress the immune system. The present study evaluated the screening efficacy of flow cytometric lymphocyte subset typing in peripheral blood mononuclear cells from healthy individuals (HI) and from patients with non-Hodgkin lymphoma (NHL) treated with different concentrations of FR-91, a standardized lysate of microbial cells belonging to the Bacillus genus, and in vitro cytokine production. Increased expression of subset markers (CD3, CD4, CD8) in NHL and CD3 in HI suggests an immunomodulating effect of FR-91. In addition the results of cytokine production also demonstrated a clear effect of FR-91 on both populations. A significant increase of IL-6, IL-12, IFN-gamma and TNF-alpha was observed in the HI group after treatment with FR-91. In a similar manner an increase of IL-2, IL-6, IL-12, IFN-gamma and TNF-alpha was also observed in the NHL group. In conclusion FR-91 seems to affect lymphocyte subpopulations, in vitro cytokine production, as well as mitogen-induced lymphocyte activation in a dose-dependent manner in both healthy individuals and NHL patients.

Immunological and histochemical analyses of cerebrospinal fluid and peripheral blood from patients with neurological and psychiatric disorders

Epidemiological, clinical and post mortem studies indicate that inflammatory and immune reactions are involved in the pathomechanisms of affective and schizophrenic spectrum disorders. However, in psychiatric patients, only sporadic investigation on immunochemistry has been performed and information about immunofunction derived by investigation of immunocompetent cells in the CSF is not available to date. Here we present an interdisciplinary work of neurologists, psychiatrists and hemato-immunologists focusing on the immunology of psychiatric and neurological disorders. In a first study including 63 patients with therapy resistant affective and schizophrenic spectrum disorders we applied conventional, validated neurological CSF investigation such as analysis of albumin, IgG, IgA, IgM, oligoclonal IgG and specific antibodies, cell count and interpreted the data by Reibergrams. In a second study, we applied the highly sensitive and specific multicolour flowcytometry of paired samples of CSF and peripheral blood cells to characterize the immunostatus of psychiatric and neurological patients. We demonstrate that flowcytometry technology constitutes an appropriate method to investigate subsets of lymphocytes even with low CSF cell numbers, and therefore as a promising diagnostic tool for routine purposes in the differential diagnosis of psychiatric diseases. Furthermore, knowledge of the frequencies of T cell subsets such as the T regulatory cell type might open new avenues to models of psychiatric and neurological diseases as well as diagnostic and monitoring implications.