T cytotoxic 1 and T cytotoxic 2 CD8 T cells both inhibit IgE responses

Pan-Cancer Analysis Shows Enrichment of Macrophages, Overexpression of Checkpoint Molecules, Inhibitory Cytokines, and Immune Exhaustion Signatures in EMT-High Tumors

Epithelial-mesenchymal transition (EMT) is a highly dynamic process that occurs under normal circumstances; however, EMT is also known to play a central role in tumor progression and metastasis. Furthermore, role of tumor immune microenvironment (TIME) in shaping anticancer immunity and inducing the EMT is also well recognized. Understanding the key features of EMT is critical for the development of effective therapeutic interventions. Given the central role of EMT in immune escape and cancer progression and treatment, we have carried out a pan-cancer TIME analysis of The Cancer Genome Atlas (TCGA) dataset in context to EMT. We have analyzed infiltration of various immune cells, expression of multiple checkpoint molecules and cytokines, and inflammatory and immune exhaustion gene signatures in 22 cancer types from TCGA dataset. A total of 16 cancer types showed a significantly increased (p < 0.001) infiltration of macrophages in EMT-high tumors (mesenchymal samples). Furthermore, out of the 17 checkpoint molecules we analyzed, 11 showed a significant overexpression (p < 0.001) in EMT-high samples of at least 10 cancer types. Analysis of cytokines showed significant enrichment of immunosuppressive cytokines-TGFB1 and IL10-in the EMT-high group of almost all cancer types. Analysis of various gene signatures showed enrichment of inflammation, exhausted CD8+ T cells, and activated stroma signatures in EMT-high tumors. In summary, our pan-cancer EMT analysis of TCGA dataset shows that the TIME of EMT-high tumors is highly immunosuppressive compared to the EMT-low (epithelial) tumors. The distinctive features of EMT-high tumors are as follows: (i) the enrichment of tumor-associated macrophages, (ii) overexpression of immune checkpoint molecules, (iii) upregulation of immune inhibitory cytokines TGFB1 and IL10, and (iv) enrichment of inflammatory and exhausted CD8+ T-cell signatures. Our study shows that TIMEs of different EMT groups differ significantly, and this would pave the way for future studies analyzing and targeting the TIME regulators for anticancer immunotherapy.

Permissive State of EMT: The Role of Immune Cell Compartment

The Epithelial to Mesenchymal Transition (EMT) type 3 is a reversible dynamic process recognized as a major determinant of the metastatic event, although many questions regarding its role throughout this process remain unanswered. The ability of cancer cells to migrate and colonize distant organs is a key aspect of tumor progression and evolution, requiring constant tumor cells and tumor microenvironment (TME) changes, as well as constant changes affecting the cross-talk between the two aforementioned compartments. Alterations affecting tumor cells, such as transcription factors, trans-membrane receptors, chromatin remodeling complexes and metabolic pathways, leading to the disappearance of the epithelial phenotype and concomitant gaining of the undifferentiated mesenchymal phenotype are undoubtedly major players of the EMT process. However, several lines of evidence point out toward a more critical role of TME composition in creating an “EMT-permissive state.” The “EMT-permissive state” consists in changes affecting physical and biochemical properties (i.e., stiffness and/or hypoxia) as well as changes of the TME cellular component (i.e., immune-cell, blood vessel, lymphatic vessels, fibroblasts, and fat cells) that favor and induce the epithelial mesenchymal transition. In this mini review, we will discuss the role of the tumor microenvironment cellular component that are involved in supporting the EMT, with particular emphasis on the immune-inflammatory cells component.

Antibody-suppressor CD8+ T Cells Require CXCR5

BACKGROUND

We previously reported the novel activity of alloprimed CD8 T cells that suppress posttransplant alloantibody production. The purpose of the study is to investigate the expression and role of CXCR5 on antibody-suppressor CD8 T-cell function.

METHODS

C57BL/6 mice were transplanted with FVB/N hepatocytes. Alloprimed CD8 T cells were retrieved on day 7 from hepatocyte transplant recipients. Unsorted or flow-sorted (CXCR5CXCR3 and CXCR3CXCR5) alloprimed CD8 T-cell subsets were analyzed for in vitro cytotoxicity and capacity to inhibit in vivo alloantibody production following adoptive transfer into C57BL/6 or high alloantibody-producing CD8 knock out (KO) hepatocyte transplant recipients. Alloantibody titer was assessed in CD8 KO mice reconstituted with naive CD8 T cells retrieved from C57BL/6, CXCR5 KO, or CXCR3 KO mice. Antibody suppression by ovalbumin (OVA)-primed monoclonal OVA-specific t-cell receptor transgenic CD8+ T cells (OT-I) CXCR5 or CXCR3 CD8 T-cell subsets was also investigated.

RESULTS

Alloprimed CXCR5CXCR3CD8 T cells mediated in vitro cytotoxicity of alloprimed "self" B cells, while CXCR3CXCR5CD8 T cells did not. Only flow-sorted alloprimed CXCR5CXCR3CD8 T cells (not flow-sorted alloprimed CXCR3CXCR5CD8 T cells) suppressed alloantibody production and enhanced graft survival when transferred into transplant recipients. Unlike CD8 T cells from wild-type or CXCR3 KO mice, CD8 T cells from CXCR5 KO mice do not develop alloantibody-suppressor function. Similarly, only flow-sorted CXCR5CXCR3 (and not CXCR3CXCR5) OVA-primed OT-I CD8 T cells mediated in vivo suppression of anti-OVA antibody production.

CONCLUSIONS

These data support the conclusion that expression of CXCR5 by antigen-primed CD8 T cells is critical for the function of antibody-suppressor CD8 T cells.

Th2 responses in OVA-sensitized BALB/c mice are down-modulated by Mycobacterium bovis BCG treatment

Objective

This study aimed to determine whether Mycobacterium bovis Bacillus Calmette-Guérin (BCG) treatment can reverse an established allergic airway inflammation in a BALB/c mouse model of ovalbumin (OVA)-induced airway inflammation.

Methods

OVA sensitized BALB/c mice were challenged with aerosolized OVA on days 28 to 30, 34, 41 and 63. Mice were intranasal treated with BCG on days 35 and 42. Twenty-four hours after the last challenge, blood samples were collected to detect anti-OVA immunoglobulin isotypes, and bronchoalveolar lavage (BAL) was harvested for cell count. Additionally, lungs were collected for histological analysis, detection of the eosinophil peroxidase (EPO) activity and measurement of cytokines and CCL11. The expression of CTLA-4, Foxp3 and IL-10 was also determined in lung tissue by flow cytometry.

Results

BCG treatment was able to inhibit an established allergic Th2-response, by decreasing the allergen-induced eosinophilic inflammation, EPO activity, levels of CCL11 and IL-4, serum levels of IgE and IgG1. Mycobacteria treatment increased lung levels of IFN-γ, IL-10 and TGF-β, and expressions of Foxp3 and CTLA-4 in CD4⁺T cells. Additionally, an increased production of IL-10 by CD8⁺ T cells was observed, even though no detectable changes in CD4⁺IL-10⁺ was noticed.

Conclusion

BCG treatment inhibits features of allergic airway inflammation and the results suggest that the mechanism underlying the down-regulatory effects of BCG on OVA-induced airway inflammation appear to be associated with the induction of both Th1 and T regulatory immune responses.

Overview of the immune response

The immune system has evolved to protect the host from a universe of pathogenic microbes that are themselves constantly evolving. The immune system also helps the host eliminate toxic or allergenic substances that enter through mucosal surfaces. Central to the immune system's ability to mobilize a response to an invading pathogen, toxin, or allergen is its ability to distinguish self from nonself. The host uses both innate and adaptive mechanisms to detect and eliminate pathogenic microbes, and both of these mechanisms include self-nonself discrimination. This overview identifies key mechanisms used by the immune system to respond to invading microbes and other exogenous threats and identifies settings in which disturbed immune function exacerbates tissue injury.

Antigen-primed splenic CD8+ T cells impede the development of oral antigen-induced allergic diarrhea

BACKGROUND

Although CD4+ T-cell populations are thought to be involved in the pathophysiology of food allergy and oral tolerance, the role of CD8+ T cells remains uncertain.

OBJECTIVE

We analyzed regulatory effects of adoptively transferred CD8+ T cells on the development of allergic diarrhea in antigen-sensitized mice that had a significantly reduced number of conventional TCRalphabeta+ CD8+ T cells.

METHODS

Ovalbumin-specific T-cell receptor transgenic mice were systemically sensitized to ovalbumin. Splenic CD8+ T cells purified from ovalbumin-sensitized or nonsensitized wild-type mice or IL-10 knockout mice were adoptively transferred to ovalbumin-sensitized ovalbumin-specific T-cell receptor transgenic mice. Allergic diarrhea induced by oral administration of ovalbumin, ovalbumin-specific immunoglobulin production, and cytokine production in intestines and mesenteric lymph nodes were assessed.

RESULTS

Adoptive transfer of splenic CD8+ T cells from ovalbumin-primed mice, but not from nonprimed mice, suppressed the development of allergic diarrhea, which was associated with in vivo increased IL-10 mRNA expression and in vitro antigen-specific IL-10 production by mesenteric lymph node cells. Upregulation of serum ovalbumin-specific IgE was not suppressed by ovalbumin-primed CD8+ T-cell transfer. Although administration of IL-10 before ovalbumin challenge failed to alleviate allergic diarrhea, transfer of splenic CD8+ T cells from IL-10 knockout mice showed diminished preventive effects.

CONCLUSION

Systemic immunization with allergen simultaneously induces regulatory CD8+ T cells that can inhibit the development of allergic diarrhea. IL-10 production by regulatory CD8+ T cells appears to be partially involved in these inhibitory mechanisms.

CD8+ T cells in asthma: friend or foe?

While it is well established that CD4(+) T lymphocytes play a crucial role in the initiation, progression and persistence of asthma, the role of CD8(+) T cells is less understood. CD8(+) T cells form functionally similar subsets which exhibit similar cytokine profiles as Th1 and Th2 cells, known as Tc1 and Tc2. Evidence from animal studies suggest that CD8(+) T cells are capable of regulating IgE production through the induction of IL-12 and IL-18 production in dendritic cells, and that CD8(+) T cells may act to moderate Th2 polarisation within the localised lymph nodes during allergic sensitisation. Such findings have led to the suggestion that Th1 polarising, CD8(+) T cell-inducing vaccines would inhibit the development of airway hyperresponsiveness (AHR) and Th2 cell infiltration. Despite these positive findings, the role of CD8(+) T cells within the lung remains poorly understood. While CD8(+) T cells, particularly those expressing the Tc1 phenotype, are capable of moderating inflammation and suppressing AHR, it has been postulated that Tc2 CD8(+) T cells predominate within established asthma and may act to amplify the inappropriate immune response which defines the condition. Within the clinic, the association between CD8(+) T cells and asthma is almost universally defined as injurious, further suggesting a prejudicial role for these cells within the established disease. CD8(+) T cells may be a valuable potential target for therapeutic intervention, either by potentiating their regulatory effects prior to the development of sensitisation, or through suppressing their pro-inflammatory properties within established atopy.

Allergen immunotherapy in intermittent allergic rhinitis reduces the intracellular expression of IL-4 by CD8+ T cells

BACKGROUND

T helper subset dysregulation is evident in allergic disorders. The role of T cytotoxic subsets is less understood. We investigated whether allergen immunotherapy in intermittent allergic rhinitis influences the intracellular expression of IL-4 and IFN-gamma by CD3+CD8(-) and CD3+CD8+ cells.

METHODS

Nineteen adult patients with intermittent allergic rhinitis were evaluated before the pollen season, and then after one preseasonal course of subcutaneous allergen immunotherapy. Twelve healthy nonatopic patients matched for age and sex served as controls. Intracellular expression of IFN-gamma and IL-4 by CD3+CD8(-) (Th1 and Th2, respectively) and CD3+CD8+ (Tc1 and Tc2, respectively) was estimated by flow cytometry in peripheral blood cells after stimulation with PMA and ionomycin.

RESULTS

Before immunotherapy the percentages of Th1, Th2, Tc1 and Tc2 did not significantly differ between the patients and the controls. After immunotherapy the percentage of Tc2 was lower in the rhinitic patients than in the controls (0.38% vs. 0.45%, p=0.04). The percentage of Tc2 cells decreased significantly after immunotherapy in the intermittent allergic rhinitis group (0.64% vs. 0.38%, p=0.02) with tendency to decrease in ratios of Tc2/Tc1 (p=0.059) and with no changes in ratios of Th2/Th1. The percentages of Th1, Th2 and Tc1 were comparable before and after immunotherapy within the rhinitic patient group.

CONCLUSIONS

The preseasonal allergen subcutaneous immunotherapy applied to intermittent allergic rhinitis patients suppressed the percentage of IL-4 producing CD3+CD8+ cells. Decreased number of CD3+CD8+IL-4+ cells may participate in the regulatory mechanisms of immunotherapy.

New aspects on inflammation in allergic diseases

BACKGROUND

Allergic disease has currently reached epidemic proportions, with a high percentage of individuals in the developed world exhibiting an allergic response after exposure to some common environmental factors. Although new strategies for the treatment and management of allergic diseases have decreased the mortality rate, a high percentage of affected persons still require frequent hospitalization and experience decreased quality of life.

METHODS

An internet-based literature search was performed for recent contributions on the underlying mechanisms provoking an allergic response and their potential for therapeutic approaches.

RESULTS

Novel concepts on allergic responses have emerged: allergic disease may result from an imbalance between allergen activation of regulatory T cells and effector T helper 2 cells (Th2), a process in which dendritic cells are key players. Cytokines such as interleukin (IL)-6, IL-21, IL-25, and human thymic stromal lymphopoietin (TSLP) seem to be important contributors in allergic processes. New data on IgE effector responses and on the IgE-independent mechanisms involved in allergic reactions have resolved some unanswered questions about these reactions.

CONCLUSIONS

These new findings on allergic diseases have important implications for diagnosis and management, with potential improvements in prevention and treatment, which could provide a cure in the future.

Is Genetic Vaccination against Allergy Possible?

Genetic immunization has proven a powerful method to induce antiallergic immune responses. The underlying functional principle has been described to be based on the recruitment of allergen-specific Th1 cells, CD8+ cells and the establishment of a Th1 cytokine milieu, which prevent the development of a Th2-biased response in a protective setup and can balance an ongoing Th2-type response in a therapeutic situation. Genetic immunization with plasmid DNA offers innovative solutions to the major problems associated with protein immunization, such as crosslinking of pre-existing immunoglobulin E on mast cells/basophils or induction of de novo synthesis of immunoglobulin E by the protein immunization itself. It easily enables the routine production of hypoallergenic vaccines, which do not translate native allergens, thus avoiding potential anaphylactic side effects. DNA vaccines can also be applied as mixtures of single vaccines, making them interesting candidates for treatment based on component-resolved diagnosis, followed by an individualized therapy with the relevant allergens. In addition to the description of up-to-date allergen gene vaccine approaches, this review gives an overview of animal studies dealing with the following topics: danger signals as the inherent adjuvant properties, methods to optimize the vaccine immunogenicity, modulation of the immune response, nonparenteral applications and low-dose vaccination strategies.

In vivo IgE levels in exogenous antigen stimulated responses: measurement of total IgE as a valid, simple surrogate for Ag-specific IgE

Due to its dependence on IL-4 and IL-13 production, IgE production is frequently used to assess the type 2 character of an immune effector response. It is particularly relevant to measure IgE in murine models of immediate hypersensitivity, as allergen specific IgE is a critical effector molecule in this process. Given the complexity of developing ELISAs to measure specific IgE, total IgE levels are often reported with the implicit assumption that this provides an accurate gauge of specific IgE responses. Here, we rigorously test this assumption by examining the relationship between total and Ag-specific IgE levels in mice immunized to elicit a wide range of serum IgE responses. We identify a strong, consistent relationship between total and Ag-specific IgE, regardless of the phenotype of the immune response (type 1 vs. type 2 biased), the nature of the immune response (primary vs. recall), the genetic background of mouse strain examined (C57Bl/6, BALB/c or outbred CD1 mice), or the intensity of the initial immunological stimulus (0.2, 2.0 or 100 microg OVA). These findings indicate that measurement of total IgE levels through straightforward, easy to develop, total IgE ELISAs offers an appropriate surrogate for measurement of Ag-specific IgE levels, usually measured through the use of subjective PCA assays or Ag-specific IgE ELISAs.

T-cell immunotherapy of allergic disease: the role of CD8+ T cells

PURPOSE OF REVIEW

The scope of this review is to place recent advances in T-cell immunotherapy into an account of our understanding of the potential role of CD8+ T cells in the pathogenesis of allergic disease.

RECENT FINDINGS

Studies over the last year suggest that changes in CD8+ T-cell function may represent key events in successful T-cell immunotherapy. The first human human leukocyte antigen class I allergen epitopes have now been described and will provide further insights into the role of allergen-specific CD8+ T cells.

SUMMARY

The coupling of recent technical advances in the study of antigen-specific T cells with the knowledge of human allergen class I epitopes will promote rapid progress in the field, with potential consequences for the diagnosis, monitoring and immunotherapeutic treatment of affected individuals.

Genetic attachment of undecane peptides to ovomucoid third domain can suppress the production of specific IgG and IgE antibodies

An undecane peptide (Gly-Ser-Pro-Gly-Ile-Pro-Gly-Ser-Thr-Gly-Met) was genetically attached to the N-terminus of ovomucoid third domain (DIII) to investigate structural characteristics of linear IgE and IgG (B cell) epitopes in DIII with respect to modulation of the immune response towards antigenicity and allergenicity. Balb/c mice were sensitized with native DIII, wild type recombinant DIII, and recombinant modified DIII containing the extra amino acid stretch. The immune responses to the antigens were compared using enzyme-linked immunosorbent assay. Interestingly, specific IgE and IgG levels were suppressed when the modified DIII was used as antigen. This was further confirmed by synthesizing immunodominant IgE and IgG epitopes of DIII on cellulose acetate membrane (SPOTs) and probing them with antibodies raised against DIII antigens. Anti-recombinant wild type DIII anti-serum showed strong binding activities to immunodominant IgE and IgG epitopes, while anti-modified DIII serum did not show any significant binding to the IgE and IgG epitopes. Thus, it is clearly demonstrated that the amino acid stretch in DIII is masking the immune reactive epitope. Genetical attachment of peptides into DIII was found to be effective in reducing the production of specific IgE and IgG antibodies in mice.

1. Overview of the immune response

Host defense against pathogenic microbes requires dramatically different responses, depending on the character of the pathogen and on the tissue under attack. Central to the immune system's ability to mobilize a response to an invading pathogen is its ability to distinguish self from nonself. The host has evolved both innate and adaptive mechanisms to respond to and eliminate pathogenic microbes. Both of these mechanisms include self-nonself discrimination. This overview describes key mechanisms used by the immune system to respond to invading microbes and identifies settings in which disturbed immune function exacerbates tissue injury.

Allergen-specific CD8(+) T cells and atopic disease

Considerable evidence suggests that IL-10 may have a role in the manifestation of atopic disease. We sought to test the hypothesis that at the single cell level, allergen-specific T cells have diminished IL-10 production capacity in severely affected atopics compared with asymptomatic atopics. We defined three A*0201-restricted Der p 1 CD8(+) T cell epitopes. Using human leukocyte antigen-A*0201-peptide (HLA-A*0201-peptide) tetrameric complexes and enzyme-linked immunospot assays to analyze peripheral blood mononuclear cells from A*0201-positive severely symptomatic atopics, asymptomatic atopics, and nonatopic controls, we observed a significant association between the frequency of the Der p 1-specific CD8(+) T cells and disease activity. The specific T cells expressed an antigen-experienced cell surface phenotype, and 45.7% were positive for cutaneous lymphocyte-associated antigen. The specific T cells were able to produce IFN-gamma efficiently, but their IL-10 production was significantly reduced in severely affected atopics. In contrast, viral-specific CD8(+) T cells were able to produce equivalent amounts of IL-10 in the severely affected atopics compared with asymptomatic atopics and nonatopics. Through defining the first human atopic allergen HLA class I epitopes, we have provided a possible cellular mechanism to link the previous association of low IL-10 levels and severe atopic disease. These data are consistent with a role for CD8(+) T cells in atopic disease pathogenesis and may provide a basis for future T cell immunotherapy strategies.