Regulating functional cell fates in CD8 T cells

MHC-II presentation by oral Langerhans cells impacts intraepithelial Tc17 abundance and Candida albicans oral infection via CD4 T cells

In a murine model (LCΔMHC-II) designed to abolish MHC-II expression in Langerhans cells (LCs), ∼18% of oral LCs retain MHC-II, yet oral mucosal CD4 T cells numbers are unaffected. In LCΔMHC-II mice, we now show that oral intraepithelial conventional CD8αβ T cell numbers expand 30-fold. Antibody-mediated ablation of CD4 T cells in wild-type mice also resulted in CD8αβ T cell expansion in the oral mucosa. Therefore, we hypothesize that MHC class II molecules uniquely expressed on Langerhans cells mediate the suppression of intraepithelial resident-memory CD8 T cell numbers via a CD4 T cell-dependent mechanism. The expanded oral CD8 T cells co-expressed CD69 and CD103 and the majority produced IL-17A [CD8 T cytotoxic (Tc)17 cells] with a minority expressing IFN-γ (Tc1 cells). These oral CD8 T cells showed broad T cell receptor Vβ gene usage indicating responsiveness to diverse oral antigens. Generally supporting Tc17 cells, transforming growth factor-β1 (TGF-β1) increased 4-fold in the oral mucosa. Surprisingly, blocking TGF-β1 signaling with the TGF-R1 kinase inhibitor, LY364947, did not reduce Tc17 or Tc1 numbers. Nonetheless, LY364947 increased γδ T cell numbers and decreased CD49a expression on Tc1 cells. Although IL-17A-expressing γδ T cells were reduced by 30%, LCΔMHC-II mice displayed greater resistance to Candida albicans in early stages of oral infection. These findings suggest that modulating MHC-II expression in oral LC may be an effective strategy against fungal infections at mucosal surfaces counteracted by IL-17A-dependent mechanisms.

LdCyPA attenuates MAPK pathway to assist Leishmania donovani immune escape in host cells

BACKGROUND

Visceral leishmaniasis is a neglected tropical disease affecting millions of people worldwide. Macrophages serve as the primary host cells for L. donovani, the immune response capability of these host cells is crucial for parasites' intracellular survival. L. donovani peptidyl-prolyl cis/trans isomerase Cyclophilin A (LdCypA) is a key protein for L. donovani intracellular proliferation, while the molecular mechanism conducive to intracellular survival of parasites remains elusive.

METHODS

In this study, we generated a macrophage cell line overexpressing LdCyPA to investigate its role in controlling host immunity and promoting intracellular immune escape of L. donovani.

RESULTS

It was discovered that the overexpression of the LdCyPA cell line regulated the host immune response following infection by downregulating the proportion of M1-type macrophages, promoting the secretion of the anti-inflammatory factor IL-4, and inhibiting the secretion of pro-inflammatory factors like IL-12, IFN-γ, TNF-α, and INOS. Transcriptome sequencing and mechanistic validation, meanwhile, demonstrated that cells overexpressing LdCyPA controlled the immune responses that followed infection by blocking the phosphorylation of P38 and JNK1/2 proteins in the MAPK signaling pathway and simultaneously increasing the phosphorylation of ERK proteins, which helped the L. donovani escape immune recognition.

CONCLUSION

Our findings thus pave the way for the development of host-directed antiparasitic drugs by illuminating the pro-Leishmania survival mechanism of L. donovani cyclophilin A and exposing a novel immune escape strategy for L. donovani that targets host cellular immune regulation.

Interleukin (IL)-9 Supports the Tumor-Promoting Environment of Chronic Lymphocytic Leukemia

Simple Summary

Interleukin 9 (IL-9), a soluble factor secreted by immune cells, has been found in several tumor niches where, depending on the specific tumor type, it either promotes or counteracts tumor development. Recently, IL-9 has been implicated in the development of chronic lymphocytic leukemia, although the underlying molecular mechanism remains unknown. Here, we summarize the current knowledge concerning the roles of IL-9 in disease, with a focus on its implication in the pathogenesis of chronic lymphocytic leukemia.

Abstract

Interleukin (IL)-9 is a soluble factor secreted by immune cells into the microenvironment. Originally identified as a mediator of allergic responses, IL-9 has been detected in recent years in several tumor niches. In solid tumors, it mainly promotes anti-tumor immune responses, while in hematologic malignancies, it sustains the growth and survival of neoplastic cells. IL-9 has been recently implicated in the pathogenesis of chronic lymphocytic leukemia; however, the molecular mechanisms underlying its contribution to this complex neoplasia are still unclear. Here, we summarize the current knowledge of IL-9 in the tumor microenvironment, with a focus on its role in the pathogenesis of chronic lymphocytic leukemia.

Professional killers: The role of extracellular vesicles in the reciprocal interactions between natural killer, CD8+ cytotoxic T-cells and tumour cells

Extracellular vesicles (EVs) mediate the cross‐talk between cancer cells and the cells of the surrounding Tumour Microenvironment (TME). Professional killer cells include Natural Killer (NK) cells and CD8+ Cytotoxic T‐lymphocytes (CTLs), which represent some of the most effective immune defense mechanisms against cancer cells. Recent evidence supports the role of EVs released by NK cells and CTLs in killing cancer cells, paving the road to a possible therapeutic role for such EVs. This review article provides the state‐of‐the‐art knowledge on the role of NK‐ and CTL‐derived EVs as anticancer agents, focusing on the different functions of different sub‐types of EVs. We also reviewed the current knowledge on the effects of cancer‐derived EVs on NK cells and CTLs, identifying areas for future investigation in the emerging new field of EV‐mediated immunotherapy of cancer.

Retinoic Acid Is Elevated in the Mucosa of Patients With Active Ulcerative Colitis and Displays a Proinflammatory Role by Augmenting IL-17 and IFNγ Production

BACKGROUND

All-trans retinoic acid (RA) plays a crucial role in promoting Foxp3+ Treg generation while reciprocally inhibiting Th1/Th17 generation. Our previous research highlighted that in the face of inflammatory conditions, RA plays a contrary role where it aggravates intestinal inflammation by promoting interferon (IFN) γ and interleukin (IL)-17 differentiation in vitro.

METHODS

In this study we translated our in vitro results into a clinical setting where we estimated mucosal and serum RA levels along with the immunophenotypic profile (IL-17, IFNγ, Foxp3, IL-10) in adaptive (CD4, CD8) and innate-like T cells (mucosal associated invariant T cells and γδ T cells) in patients with ulcerative colitis in remission or with active inflammation.

RESULTS

This is the first study to estimate RA levels in the human gut and shows that patients with active disease had increased mucosal RA levels as compared with patients in remission (4.0 vs 2.5 ng/mL; P < 0.01) and control patients (3.4 vs 0.8 ng/mL; P < 0.0001). This effect was accompanied by significantly elevated IL-17 and IFNγ in tissue CD4+, CD8+, mucosal associated invariant T+ cells, and γδ + T cells. Moreover, the raised RA levels in patients with active disease showed a positive correlation with proinflammatory cytokines (IL-17, IFNγ) and a negative correlation with IL-10. We also found that RA negatively correlated with IL-9, thereby reinstating our previous finding that RA inhibits Th9 differentiation.

CONCLUSIONS

These data confirm our previous in vitro results that in the presence of inflammation, RA plays a crucial role in maintaining gut inflammation by upregulating proinflammatory markers.

Correlations of disease severity and age with hematology parameter variations in patients with COVID-19 pre- and post-treatment

Background

For better understanding of the pathological changes of COVID‐19, benefiting clinical management of the disease and the preparation for future waves of similar pandemics.

Methods

Hematology parameters from a total of 52 cases of COVID‐19 admitted for treatment in a designated hospital were retrospectively analyzed. Data were analyzed by SPSS statistical software.

Results

Pre‐treatment T‐cell subsets, total lymphocytes, red blood cell distribution width (RDW), eosinophils, and basophils were significantly lower than that of post‐treatment, while the inflammatory indexes neutrophils, neutrophil to lymphocyte ratio (NLR), and C‐reactive protein (CRP) levels, as well as red blood cell (RBC) and hemoglobin, were significantly reduced after treatment. The T‐cell subsets, total lymphocytes, and basophils in severely and critically ill patients were significantly lower than those in moderately ill patients. Neutrophils, NLR, eosinophils, procalcitonin (PCT), and CRP was significantly higher in severely and critically ill patients than in moderately ill patients. CD3+, CD8+, total lymphocytes, platelets, and basophils in patients older than 50 were lower than that of those younger than 50, while neutrophils, NLR, CRP, and RDW in patients older than 50 were higher than that of younger than 50. There was a positive correlation among prothrombin time (PT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) in severely and critically ill patients.

Conclusions

T‐cell subsets, lymphocyte count, RDW, neutrophils, eosinophils, NLR, CRP, PT, ALT, and AST are important indicators in the management especially for severely and critically ill patients with COVID‐19.

Amelioration of Autoimmune Diabetes of NOD Mice by Immunomodulating Probiotics

Type 1 autoimmune diabetes is an autoimmune disease characterized by specific destruction of pancreatic β-cells producing insulin. Recent studies have shown that gut microbiota and immunity are closely linked to systemic immunity, affecting the balance between pro-inflammatory and regulatory immune responses. Altered gut microbiota may be causally related to the development of immune-mediated diseases, and probiotics have been suggested to have modulatory effects on inflammatory diseases and immune disorders. We studied whether a probiotic combination that has immunomodulatory effects on several inflammatory diseases can reduce the incidence of diabetes in non-obese diabetic (NOD) mice, a classical animal model of human T1D. When Immune Regulation and Tolerance 5 (IRT5), a probiotic combination comprising Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus reuteri, Bifidobacterium bifidium, and Streptococcus thermophiles, was administered 6 times a week for 36 weeks to NOD mice, beginning at 4 weeks of age, the incidence of diabetes was significantly reduced. Insulitis score was also significantly reduced, and β-cell mass was conversely increased by IRT5 administration. IRT5 administration significantly reduced gut permeability in NOD mice. The proportion of total regulatory T cells was not changed by IRT5 administration; however, the proportion of CCR9⁺ regulatory T (Treg) cells expressing gut-homing receptor was significantly increased in pancreatic lymph nodes (PLNs) and lamina propria of the small intestine (SI-LP). Type 1 T helper (Th1) skewing was reduced in PLNs by IRT5 administration. IRT5 could be a candidate for an effective probiotic combination, which can be safely administered to inhibit or prevent type 1 diabetes (T1D).

IL-9 and IL-9-producing cells in tumor immunity

Abstract

Interleukin (IL)-9 belongs to the IL-2Rγc chain family and is a multifunctional cytokine that can regulate the function of many kinds of cells. It was originally identified as a growth factor of T cells and mast cells. In previous studies, IL-9 was mainly involved in the development of allergic diseases, autoimmune diseases and parasite infections. Recently, IL-9, as a double-edged sword in the development of cancers, has attracted extensive attention. Since T-helper 9 (Th9) cell-derived IL-9 was verified to play a powerful antitumor role in solid tumors, an increasing number of researchers have started to pay attention to the role of IL-9-skewed CD8⁺ T (Tc9) cells, mast cells and Vδ2 T cell-derived IL-9 in tumor immunity. Here, we review recent studies on IL-9 and several kinds of IL-9-producing cells in tumor immunity to provide useful insight into tumorigenesis and treatment.

Dual-target IL-12-containing nanoparticles enhance T cell functions for cancer immunotherapy

Cytotoxic T lymphocytes (CTLs) play a major role in cancer immunotherapy. A potent tumor immunotherapy may not only require activation of anti-tumor effector cells but also rely on the use of cytokines to create a controlled environment for the development of anti-tumor T cells. In this study, we fabricated a dual-target immunonanoparticle, e.g. poly(d,l-lactide-co-glycolide) nanoparticle, by loading Interleukin-12 (IL-12) and modifying with CD8 and Glypican-3 antibodies on the surface. Our results demonstrate that the fabricated targeting immunonanoparticles bind specifically to the two target cells of interest, i.e. CD8+ T cells and HepG-2 cells via the antibody-antigen interactions and form T cell-HepG-2 cell clusters, which enhances the cytotoxicity of T cells. IL-12-containing dual-target immunonanoparticles delivered IL-12 specifically to CD8+ T cells, and favored the expansion, activation and cytotoxic activity of CD8+ T lymphocytes. These results suggest that dual-target IL-12-encapsulated nanoparticles are a promising platform for cancer immunotherapy.

Yogurt starter cultures of Streptococcus thermophilus and Lactobacillus bulgaricus ameliorate symptoms and modulate the immune response in a mouse model of dextran sulfate sodium-induced colitis

We investigated the yogurt starter cultures of Lactobacillus bulgaricus 151 and Streptococcus thermophilus MK-10 for their effect on the severity of experimental colitis, lymphocyte profile, and regulatory T-cell response. Colitis was induced in BALB/c mice via the administration of 3.5% dextran sulfate sodium salt (DSS) in drinking water for 6 d. Next, the mice were gavaged intragastrically with an active yogurt cultures (YC) mixture (∼5 × 10⁹ cfu/mouse per day) or saline (vehicle) for 8 d. Mice receiving DSS or saline alone served as positive and negative controls, respectively. The length of the colon, disease activity index, histological scores, myeloperoxidase activity, epithelium-associated microbes, short-chain fatty acid profile, total IgA antibody-forming cells, CD3⁺CD8⁺, CD3⁺CD4⁺, CD3⁺CD4⁺CD25⁺, CD3⁺CD4⁺CD25⁺Foxp3⁺ T-cell subsets, and cytokine profiles (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-γ, and tumor necrosis factor) were examined after termination of the mice. Feeding mice with YC mixture reduced disease symptoms and modified intestinal microbiota and host inflammatory responsiveness to DSS. We observed limited weight loss and a decreased disease activity index score, lowered myeloperoxidase activity, and somewhat reduced damage of the intestine. The YC mixture upregulated the colon length, increased the amount and diversity of mucosa-associated microbes (enterobacteria, enterococci, and yeast), and decreased the concentration of putrefactive short-chain fatty acids in the cecal contents. It downregulated the input of cytotoxic CD3⁺CD8⁺ T cells and CD3⁺CD4⁺CD25⁺FoxP3⁺ regulatory T cells in Peyer's patches and enhanced CD3⁺CD4⁺CD25⁺ T cells in spleens and CD3⁺CD4⁺CD25⁺FoxP3⁺ cells in peripheral blood mononuclear cells. Simultaneously, IgA antibody-forming cells were downregulated in mesenteric lymph nodes (MLN) and enhanced in spleens (SPL). The cultures mostly enhanced the production of cytokines tested in MLN and SPL, except for IL-6, which was downregulated in MLN. Interleukin-2 and IL-4 were the most upregulated in MLN, whereas IL-10, IL-4, IL-2, IFN-γ, and tumor necrosis factor were most upregulated in SPL. In serum, the YC mixture downregulated IFN-γ and clearly increased IL-2. Based on these results, we recognize the high anti-inflammatory and immunomodulatory potential of the L. bulgaricus 151 and S. thermophilus MK-10 set. The strains possess the ability to modulate the intestinal mucosal and systemic immune system toward both IgA production and induction of regulatory T cells, shifting Th1/Th2 balance.

IL-33 drives the antitumor effects of dendritic cells via the induction of Tc9 cells

Dendritic cell (DC) tumor vaccines exert their antitumor effects through the induction of effector T cells. We recently identified Tc9 cells as a new potent antitumor effector T cell subset. However, approaches to direct DCs to preferably prime antitumor Tc9 cells should be further exploited. Here, we demonstrate that the addition of interleukin (IL)-33 potently promotes the induction of Tc9 cells by DCs in vitro and in vivo. IL-33 treatment also drives the cytotoxic activities of DC-induced Tc9 cells. Notably, IL-33 treatment enhances cell survival and proliferation of DC-primed CD8⁺ T cells. More importantly, the addition of IL-33 during in vitro priming of tumor-specific Tc9 cells by DCs increases the antitumor capability of Tc9 cells. Mechanistic studies demonstrated that IL-33 treatment inhibits exhaustive CD8⁺ T cell differentiation by inhibiting PD-1 and 2B4 expression and increasing IL-2 and CD127 (IL-7 receptor-α, IL-7Rα) expression in CD8⁺ T cells. Finally, the addition of IL-33 further promotes the therapeutic efficacy of DC-based tumor vaccines in the OT-I mouse model. Our study demonstrates the important role of IL-33 in DC-induced Tc9 cell differentiation and antitumor immunity and may have important clinical implications.

Subretinal Injection of HY Peptides Induces Systemic Antigen-Specific Inhibition of Effector CD4+ and CD8+ T-Cell Responses

Purpose

Injection of an antigen into the anterior chamber of the eye induces a peripheral antigen-specific immune modulation mechanism, known as anterior chamber-associated immune deviation (ACAID). Delayed-type hypersensitivity experiments argue that the subretinal space (SR) of the eye displays properties similar to ACAID. However, no investigation was performed regarding the differential impact of a subretinal antigen injection on peripheral CD4⁺ versus CD8⁺ T cells, on the potential immune deviation regarding Th profiles, and on the antigen-specificity of the inhibition. A better understanding of these mechanisms is crucial to improve safety and immunomonitoring of ongoing therapeutic approaches targeting the SR. The aim of this study is to characterize the proliferative capacities and cytokine patterns of antigen-specific CD4⁺ and CD8⁺ T cells after a subretinal injection of antigen in mice.

Methods

Ubiquitously Transcribed tetratricopeptide repeat gene Y-linked (UTY) and DEAD Box polypeptide 3 Y-linked (DBY) peptides which respectively include MHCI- and MHCII-restricted T-cell epitopes of the mouse HY male antigen, were injected into the subretinal space of C57BL/6 female mice. 2 weeks later, these mice were immunized subcutaneously with these peptides and compared to control mice. A week later, T-cell immune responses were analyzed by IFNγ ELISpot assays and cytokine measurements (IL-2, IL-4, IL-6, IL-10, IL-13, IL-17a, IFNγ, TNFα, GM-CSF, and MCP-1) in the spleen and with proliferation assays in draining lymph nodes.

Results

Immune cells from mice that received HY peptides in the SR before immunization, compared with those from control immunized mice, secreted significantly smaller quantities of Th1/Tc1, Th2/Tc2, and Th17/Tc17 cytokines, and HY-specific CD4⁺ T cells proliferated less in response to HY peptides.

Conclusion

Taken together, our data clearly demonstrate that the subretinal injection of HY peptides induces a systemic HY-specific inhibition of conventional Th profiles and CD8⁺ T cells. We propose to call this phenomenon SRAII, for subretinal-associated immune inhibition.

ArtinM Mediates Murine T Cell Activation and Induces Cell Death in Jurkat Human Leukemic T Cells

The recognition of cell surface glycans by lectins may be critical for the innate and adaptive immune responses. ArtinM, a d-mannose-binding lectin from Artocarpus heterophyllus, activates antigen-presenting cells by recognizing TLR2 N-glycans and induces Th1 immunity. We recently demonstrated that ArtinM stimulated CD4⁺ T cells to produce proinflammatory cytokines. Here, we further studied the effects of ArtinM on adaptive immune cells. We showed that ArtinM activates murine CD4⁺ and CD8⁺ T cells, augmenting their positivity for CD25, CD69, and CD95 and showed higher interleukin (IL)-2 and interferon (IFN)-γ production. The CD4⁺ T cells exhibited increased T-bet expression in response to ArtinM, and IL-2 production by CD4⁺ and CD8⁺ T cells depended on the recognition of CD3εγ-chain glycans by ArtinM. The ArtinM effect on aberrantly-glycosylated neoplastic lymphocytes was studied in Jurkat T cells, in which ArtinM induced IL-2, IFN-γ, and IL-1β production, but decreased cell viability and growth. A higher frequency of AnnexinV- and propidium iodide-stained cells demonstrated the induction of Jurkat T cells apoptosis by ArtinM, and this apoptotic response was reduced by caspases and protein tyrosine kinase inhibitors. The ArtinM effects on murine T cells corroborated with the immunomodulatory property of lectin, whereas the promotion of Jurkat T cells apoptosis may reflect a potential applicability of ArtinM in novel strategies for treating lymphocytic leukemia.

Divide, Conquer, and Sense: CD8+CD28- T Cells in Perspective

Understanding the rationale for the generation of a pool of highly differentiated effector memory CD8⁺ T cells displaying a weakened capacity to scrutinize for peptides complexed with major histocompatibility class I molecules via their T cell receptor, lacking the “signal 2” CD28 receptor, and yet expressing a highly diverse array of innate receptors, from natural killer receptors, interleukin receptors, and damage-associated molecular pattern receptors, among others, is one of the most challenging issues in contemporary human immunology. The prevalence of these differentiated CD8⁺ T cells, also known as CD8⁺CD28⁻, CD8⁺KIR⁺, NK-like CD8⁺ T cells, or innate CD8⁺ T cells, in non-lymphoid organs and tissues, in peripheral blood of healthy elderly, namely centenarians, but also in stressful and chronic inflammatory conditions suggests that they are not merely end-of-the-line dysfunctional cells. These experienced CD8⁺ T cells are highly diverse and capable of sensing a variety of TCR-independent signals, which enables them to respond and fine-tune tissue homeostasis.

Novel CD8+ T-Cell Subsets Demonstrating Plasticity in Patients with Inflammatory Bowel Disease

BACKGROUND

Distinct CD8+ T-cell subsets such as interleukin-17-expressing Tc17 and Foxp3-expressing Tcreg are functionally similar to CD4+ T cells. Though CD4+ T cells are dysregulated in patients with inflammatory bowel disease (IBD), CD8+ T cells are not well investigated. Vitamin D is an environmental factor which influences T-cell subsets. We assessed the prevalence of CD8+ T-cell subsets among peripheral blood mononuclear cells (PBMC) and lamina propria mononuclear cells (LPMC) of patients with Crohn's disease, patients with ulcerative colitis, and healthy controls. We then tested the effect of 1α,25-dihydroxyvitamin D3 on CD8+ T-cell subsets.

METHODS

A total of 73 patients with Crohn's disease, 49 patients with ulcerative colitis, and 47 healthy controls were studied. LPMC or PBMC were isolated and flow cytometry was performed. CD3+ T cells, isolated from PBMC, were cultured with or without 1α,25-dihydroxyvitamin D3, before flow cytometry.

RESULTS

In LPMC, the prevalence of Tcreg was higher in patients with IBD (P < 0.05), whereas Tc17 were higher in patients with ulcerative colitis compared with patients with Crohn's disease and healthy controls (P < 0.05). In PBMC, both Tcreg and Tc17 were higher in patients with IBD (P < 0.01). Double-expressing interferon-γ+ interleukin-17+ and Foxp3+ interleukin-17+ CD8+ T cells were also identified indicating possible CD8+ plasticity. 1α,25-dihydroxyvitamin D3 decreased interferon-γ-expressing Tc1 (P < 0.05), but had no effect on Tc17 or Tcreg.

CONCLUSIONS

The prevalence of novel CD8+ T-cell subsets is altered in patients with IBD. Double-expressing cells indicate plasticity and were identified in patients with IBD. Vitamin D may have a limited effect on CD8+ T cells by decreasing interferon-γ expression.

Escaping Deleterious Immune Response in Their Hosts: Lessons from Trypanosomatids

The Trypanosomatidae family includes the genera Trypanosoma and Leishmania, protozoan parasites displaying complex digenetic life cycles requiring a vertebrate host and an insect vector. Trypanosoma brucei gambiense, Trypanosoma cruzi, and Leishmania spp. are important human pathogens causing human African trypanosomiasis (HAT or sleeping sickness), Chagas' disease, and various clinical forms of Leishmaniasis, respectively. They are transmitted to humans by tsetse flies, triatomine bugs, or sandflies, and affect millions of people worldwide. In humans, extracellular African trypanosomes (T. brucei) evade the hosts' immune defenses, allowing their transmission to the next host, via the tsetse vector. By contrast, T. cruzi and Leishmania sp. have developed a complex intracellular lifestyle, also preventing several mechanisms to circumvent the host's immune response. This review seeks to set out the immune evasion strategies developed by the different trypanosomatids resulting from parasite-host interactions and will focus on: clinical and epidemiological importance of diseases; life cycles: parasites-hosts-vectors; innate immunity: key steps for trypanosomatids in invading hosts; deregulation of antigen-presenting cells; disruption of efficient specific immunity; and the immune responses used for parasite proliferation.

Leger AJ, Yu CR, He C, Mahdi RM, Chan CC, Wang H, Morse HC, Egwuagu CE. Interferon Regulator Factor 8 (IRF8) Limits Ocular Pathology during HSV-1 Infection by Restraining the Activation and Expansion of CD8+ T Cells

Interferon Regulatory Factor-8 (IRF8) is constitutively expressed in monocytes and B cell lineages and plays important roles in immunity to pathogens and cancer. Although IRF8 expression is induced in activated T cells, the functional relevance of IRF8 in T cell-mediated immunity is not well understood. In this study, we used mice with targeted deletion of Irf8 in T-cells (IRF8KO) to investigate the role of IRF8 in T cell-mediated responses during herpes simplex virus 1 (HSV-1) infection of the eye. In contrast to wild type mice, HSV-1-infected IRF8KO mice mounted a more robust anti-HSV-1 immune response, which included marked expansion of HSV-1-specific CD8⁺ T cells, increased infiltration of inflammatory cells into the cornea and trigeminal ganglia (TG) and enhanced elimination of virus within the trigeminal ganglion. However, the consequence of the enhanced immunological response was the development of ocular inflammation, limbitis, and neutrophilic infiltration into the cornea of HSV-1-infected IRF8KO mice. Surprisingly, we observed a marked increase in virus-specific memory precursor effector cells (MPEC) in IRF8KO mice, suggesting that IRF8 might play a role in regulating the differentiation of effector CD8⁺ T cells to the memory phenotype. Together, our data suggest that IRF8 might play a role in restraining excess lymphocyte proliferation. Thus, modulating IRF8 levels in T cells can be exploited therapeutically to prevent immune-mediated ocular pathology during autoimmune and infectious diseases of the eye.

Exploiting IL-17-producing CD4+ and CD8+ T cells to improve cancer immunotherapy in the clinic

Cancer immunotherapy is one the most effective approaches for treating patients with tumors, as it bolsters the generation and persistence of memory T cells. In preclinical work, it has been reported that adoptively transferred CD4+ and CD8+ lymphocytes that secrete IL-17A (i.e., Th17 and Tc17 cells) regress tumors to a greater extent than IFN-γ(+)Th1 or Tc1 cells in vivo. Herein, we review the mechanisms underlying how infused Th17 and Tc17 cells regress established malignancies in clinically relevant mouse models of cancer. We also discuss how unique signaling cues--such as co-stimulatory molecules (ICOS and 41BB), cytokines (IL-12 and IL-23) or pharmaceutical reagents (Akt inhibitors, etc.)--can be exploited to bolster the therapeutic potential of IL-17(+) lymphocytes with an emphasis on using this knowledge to improve next-generation clinical trials for patients with cancer.

Natural killer group 2D and CD28 receptors differentially activate mammalian/mechanistic target of rapamycin to alter murine effector CD8+ T-cell differentiation

Memory CD8+ T cells are an essential component of anti-tumour and anti-viral immunity. Activation of the mammalian/mechanistic target of rapamycin (mTOR) pathway has been implicated in regulating the differentiation of effector and memory T cells. However, the mechanisms that control mTOR activity during immunity to tumours and infections are not well known. Activation of co-stimulatory receptors, including CD28 and natural killer group 2D (NKG2D), activate phosphatidylinositol-3 kinase and subsequently may activate the mTOR pathway in CD8+ T cells. This study compared the activation of the mTOR signalling pathway after co-stimulation through CD28 or NKG2D receptors in murine effector CD8+ T cells. Compared with CD28 co-stimulation, activation through CD3 and NKG2D receptors had weaker activation of mTORc1, as shown by decreased phosphorylation of mTORc1 targets S6K1, ribosomal protein S6 and eukaryotic initiation factor 4E binding protein 1. NKG2D co-stimulation also showed increased gene expression of tuberous sclerosis protein 2, a negative regulator of mTORc1, whereas CD28 co-stimulation increased gene expression of Ras homologue enriched in brain, an activator of mTORc1, and hypoxia-inducible factor-1α and vascular endothelial growth factor-α, pro-angiogenic factors downstream of mTORc1. Strong mTORc1 activation in CD28-co-stimulated cells also increased expression of transcription factors that support effector cell differentiation, namely T-bet, B lymphocyte-induced maturation protein (BLIMP-1), interferon regulatory factor 4, and inhibitor of DNA binding 2, whereas low levels of mTORc1 activation allowed for the expression of Eomes, B-cell lymphoma 6 (BCL6), and inhibitor of DNA binding 3 during NKG2D stimulation, and increased expression of memory markers CD62 ligand and CD127. These data show that compared with CD28, co-stimulation through the NKG2D receptor leads to the differential activation of the mTOR signalling pathway and potentially supports memory CD8+ T-cell differentiation.

Interleukin-12 enhances the function and anti-tumor activity in murine and human CD8(+) T cells

Mouse CD8(+) T cells conditioned with interleukin (IL)-12 ex vivo mediate the potent regression of established melanoma when transferred into lymphodepleted mice. However, the quantitative and qualitative changes induced by IL-12 in the responding mouse CD8(+) T cells have not been well defined. Moreover, the mechanisms by which IL-12-conditioning impacts human CD8(+) T cells, and how such cells might be expanded prior to infusion into patients is not known. We found that ex vivo IL-12-conditioning of mouse CD8(+) T cells led to a tenfold-100-fold increase in persistence and anti-tumor efficacy upon adoptive transfer into lymphodepleted mice. The enhancing effect of IL-12 was associated with maintenance of functional avidity. Importantly, in the context of ongoing ACT clinical trials, human CD8(+) T cells genetically modified with a tyrosinase-specific T cell receptor (TCR) exhibited significantly enhanced functional activity when conditioned with IL-12 as indicated by heightened granzyme B expression and elevated peptide-specific CD107a degranulation. This effect was sustainable despite the 20 days of in vitro cellular expansion required to expand cells over 1,000-fold allowing adequate cell numbers for administration to cancer patients. Overall, these findings support the efficacy and feasibility of ex vivo IL-12-conditioning of TCR-modified human CD8(+) T cells for adoptive transfer and cancer therapy.

CXCR3 expression defines a novel subset of innate CD8+ T cells that enhance immunity against bacterial infection and cancer upon stimulation with IL-15

Innate CD8(+) T cells are a heterogeneous population with developmental pathways distinct from conventional CD8(+) T cells. However, their biology, classification, and functions remain incompletely understood. We recently demonstrated the existence of a novel population of chemokine (C-X-C motif) receptor 3 (CXCR3)-positive innate CD8(+) T cells. Here, we investigated the functional properties of this subset and identified effector molecules and pathways which mediate their function. Adoptive transfer of IL-15 activated CXCR3(+) innate CD8(+) T cells conferred increased protection against Listeria monocytogenes infection in susceptible IFN-γ(-/-) mice compared with similarly activated CXCR3(-) subset. This was associated with enhanced proliferation and IFN-γ production in CXCR3(+) cells. Further, CXCR3(+) innate cells showed enhanced cytotoxicity against a tumor cell line in vitro. In depth analysis of the CXCR3(+) subset showed increased gene expression of Ccl5, Klrc1, CtsW, GP49a, IL-2Rβ, Atp5e, and Ly6c but reduced IFN-γR2 and Art2b. Ingenuity pathway analysis revealed an up-regulation of genes associated with T-cell activation, proliferation, cytotoxicity, and translational initiation in CXCR3(+) populations. Our results demonstrate that CXCR3 expression in innate CD8(+) T cells defines a subset with enhanced cytotoxic potential and protective antibacterial immune functions. Immunotherapeutic approaches against infectious disease and cancer could utilize CXCR3(+) innate CD8(+) T-cell populations as novel clinical intervention strategies.

Tissue signatures influence the activation of intrahepatic CD8(+) T cells against malaria sporozoites

Plasmodium sporozoites and liver stages express antigens that are targeted to the MHC-Class I antigen-processing pathway. After the introduction of Plasmodium sporozoites by Anopheles mosquitoes, bone marrow-derived dendritic cells in skin-draining lymph nodes are the first cells to cross-present parasite antigens and elicit specific CD8⁺ T cells. One of these antigens is the immunodominant circumsporozoite protein (CSP). The CD8⁺ T cell-mediated protective immune response against CSP is dependent on the interleukin loop involving IL-4 receptor expression on CD8⁺ cells and IL-4 secretion by CD4⁺ T cell helpers. In a few days, these CD8⁺ T cells re-circulate to secondary lymphoid organs and the liver. In the liver, the hepatic sinusoids are enriched with cells, such as dendritic, sinusoidal endothelial and Kupffer cells, that are able to cross-present MHC class I antigens to intrahepatic CD8⁺ T cells. Specific CD8⁺ T cells actively find infected hepatocytes and target intra-cellular parasites through mechanisms that are both interferon-γ-dependent and -independent. Immunity is mediated by CD8⁺ T effector or effector-memory cells and, when present in high numbers, these cells can provide sterilizing immunity. Human vaccination trials with recombinant formulations or attenuated sporozoites have yet to achieve the high numbers of specific effector T cells that are required for sterilizing immunity. In spite of the limited number of specific CD8⁺ T cells, attenuated sporozoites provided multiple times by the endovenous route provided a high degree of protective immunity. These observations highlight that CD8⁺ T cells may be useful for improving antibody-mediated protective immunity to pre-erythrocytic stages of malaria parasites.

NKG2D receptor activation of NF-κB enhances inflammatory cytokine production in murine effector CD8(+) T cells

To induce strong immune responses, naïve CD8(+) T cells require stimulation through the TCR and costimulatory receptors. However, the biological effect of activating costimulatory receptors on effector T cells is still unclear. One costimulatory receptor that is likely to be engaged at the target site is NKG2D. This activating receptor is expressed on human and murine CD8(+) T cells with its ligands expressed on the majority of tumor cells and during some infections. In order to determine how activation of costimulatory receptors alters effector CD8(+) T cell functions, this study compared the activation of the NF-κB signaling pathway by two costimulatory receptors, CD28 and NKG2D. Compared to CD28 costimulation, activation of murine effector CD8(+) T cells through CD3 and NKG2D receptors enhanced activation of NF-κB as shown by increased phosphorylation of IKKα, IκBα, and NF-κB and IκBα degradation. NKG2D costimulation also increased activation, nuclear translocation, and DNA binding of NF-κB p65/p50 dimers. Activation of the NF-κB pathway also lead to increased gene expression and secretion of pro-inflammatory cytokines, including IFNα and IFNγ, and decreased gene expression and secretion of anti-inflammatory cytokines, including IL-10 and CCL2. Altered NF-κB activation also increased expression of the effector molecules TNFα, lymphotoxins α and β, and Fas ligand, and increased tumor cell killing through FasL. These data show that compared to CD28 costimulation, activation through the NKG2D receptor leads to the differential activation of the NF-κB signaling pathway and potentially enhances the anti-tumor and anti-viral functions of effector CD8(+) T cells.

IRF4 at the crossroads of effector T-cell fate decision

Interferon regulatory factor 4 (IRF4) is a transcription factor that is expressed in hematopoietic cells and plays pivotal roles in the immune response. Originally described as a lymphocyte-specific nuclear factor, IRF4 promotes differentiation of naïve CD4(+) T cells into T helper 2 (Th2), Th9, Th17, or T follicular helper (Tfh) cells and is required for the function of effector regulatory T (eTreg) cells. Moreover, IRF4 is essential for the sustained differentiation of cytotoxic effector CD8(+) T cells, for CD8(+) T-cell memory formation, and for differentiation of naïve CD8(+) T cells into IL-9-producing (Tc9) and IL-17-producing (Tc17) CD8(+) T-cell subsets. In this review, we focus on recent findings on the role of IRF4 during the development of CD4(+) and CD8(+) T-cell subsets and the impact of IRF4 on T-cell-mediated immune responses in vivo.

Tumor-specific IL-9-producing CD8+ Tc9 cells are superior effector than type-I cytotoxic Tc1 cells for adoptive immunotherapy of cancers

Because cytokine-priming signals direct CD8(+) T cells to acquire unique profiles that affect their ability to mediate specific immune responses, here we generated IL-9-skewed CD8(+) T (Tc9) cells by priming with Th9-polarized condition. Compared with type-I CD8(+) cytotoxic T (Tc1) cells, Tc9 secreted different cytokines and were less cytolytic in vitro but surprisingly elicited greater antitumor responses against advanced tumors in OT-I/B16-OVA and Pmel-1/B16 melanoma models. After adoptive transfer, Tc9 cells persisted longer and differentiated into IFN-γ- and granzyme-B (GrzB)-producing cytolytic Tc1-like effector cells. Phenotypic analysis revealed that adoptively transferred Tc9 cells secreted IL-2 and were KLRG-1(low) and IL-7Rα(high), suggesting that they acquired a signature of "younger" phenotype or became long-term lived cells with capacity of self-renewal. Our results also revealed that Tc9-mediated therapeutic effect critically depended on IL-9 production in vivo. These findings have clinical implications for the improvement of CD8(+) T-cell-based adoptive immunotherapy of cancers.

A role for mitogen kinase kinase 3 in pulmonary inflammation validated from a proteomic approach

Proteomics is a powerful tool to ascertain which proteins are differentially expressed in the context of disease. We have used this approach on inflammatory cells obtained from patients with asthma to ascertain whether novel drugs targets could be illuminated and to investigate the role of any such target in a range of in vitro and in vivo models of inflammation. A proteomic study was undertaken using peripheral blood mononuclear cells from mild asthmatic subjects compared with healthy subjects. The analysis revealed an increased expression of the intracellular kinase, mitogen activated protein kinase (MKK3), and the function of this protein was investigated further in preclinical models of inflammation using MKK3 knockout mice. We describe a 3.65 fold increase in the expression of MKK3 in CD8(+) T lymphocytes obtained from subjects with asthma compared with healthy subjects using a proteomic approach which we have confirmed in CD8(+), but not in CD4(+) T lymphocytes or human bronchial epithelial cells from asthmatic patients using a Western blot technique. In wild type mice, bacterial lipopolysaccharide (LPS) caused a significant increase in MKK3 expression and significantly reduced airway neutrophilia in MKK3(-/-) mice (median, 25, 75% percentile; wild/LPS; 5.3 (0.7-9.9) × 10(5) cells/mL vs MKK3(-/-)/LPS; 0 (0-1.9) × 10(5) cells/mL, P < 0.05). In contrast, eosinophilia in sensitized wild type mice challenged with allergen (0.5 (0.16-0.65) × 10(5) cells/mL) was significantly increased in MKK3(-/-) mice (2.2 (0.9-3.5) × 10(5) cells/mL, P < 0.05). Our results suggest that asthma is associated with MKK3 over-expression in CD8(+) cells. We have also demonstrated that MKK3 may be critical for airway neutrophilia, but not eosinophilia, suggesting that this may be a target worthy of further consideration in the context of diseases associated with neutrophil activation such as severe asthma and COPD.

STAT3 regulates proliferation and survival of CD8+ T cells: enhances effector responses to HSV-1 infection, and inhibits IL-10+ regulatory CD8+ T cells in autoimmune uveitis

STAT3 regulates CD4⁺ T cell survival and differentiation. However, its effects on CD8⁺ T cells are not well understood. Here, we show that in comparison to WT CD8⁺ T cells, STAT3-deficient CD8⁺ T cells exhibit a preactivated memory-like phenotype, produce more IL-2, proliferate faster, and are more sensitive to activation-induced cell death (AICD). The enhanced proliferation and sensitivity to AICD correlated with downregulation of class-O forkhead transcription factors (FoxO1, FoxO3A), p21^waf1, p27^KIP1, Bcl-2, OX-40, and upregulation of FasL, Bax, and Bad. We examined whether STAT3-deficient CD8⁺ T cells can mount effective response during herpes simplex virus (HSV-1) infection and experimental autoimmune uveitis (EAU). Compared to WT mice, HSV-1-infected STAT3-deficient mice (STAT3KO) produced less IFN-γ and virus-specific KLRG-1⁺ CD8⁺ T cells. STAT3KO mice are also resistant to EAU and produced less IL-17-producing Tc17 cells. Resistance of STAT3KO to EAU correlated with marked expansion of IL-10-producing regulatory CD8⁺ T cells (CD8-Treg) implicated in recovery from autoimmune encephalomyelitis. Thus, increases of IL-6-induced STAT3 activation observed during inflammation may inhibit expansion of CD8-Tregs, thereby impeding recovery from uveitis. These results suggest that STAT3 is a potential therapeutic target for upregulating CD8⁺ T cell-mediated responses to viruses and suggest the successful therapeutic targeting of STAT3 as treatment for uveitis, derived, in part, from promoting CD8-Treg expansion.

Osteoimmunology: the study of the relationship between the immune system and bone tissue

Bone tissue is a highly regulated structure, which plays an essential role in various physiological functions. Through autocrine and paracrine mechanisms, bone tissue is involved in hematopoiesis, influencing the fate of hematopoietic stem cells. There are a number of molecules shared by bone cells and immune system cells indicating that there are multiple connections between the immune system and bone tissue. In order to pool all the knowledge concerning both systems, a new discipline known under the term «osteoimmunology» has been developed. Their progress in recent years has been exponential and allowed us to connect and increase our knowledge in areas not seemingly related such as rheumatoid erosion, postmenopausal osteoporosis, bone metastases or periodontal disease. In this review, we have tried to summarize the most important advances that have occurred in the last decade, especially in those areas of interest related to rheumatology.

Tc9 cells, a new subset of CD8(+) T cells, support Th2-mediated airway inflammation

Similar to T-helper (Th) cells, CD8(+) T cells also differentiate into distinct subpopulations. However, the existence of IL-9-producing CD8(+) T (Tc9) cells has not been elucidated so far. We show that murine CD8(+) T cells activated in the presence of IL-4 plus TGF-β develop into transient IL-9 producers characterized by specific IFN-γ and IL-10 expression patterns as well as by low cytotoxic function along with diminished expression of the CTL-associated transcription factors T-bet and Eomesodermin. Similarly to the CD4(+) counterpart, Tc9 cells required for their differentiation STAT6 and IRF4. Tc9 cells deficient for these master regulators displayed increased levels of Foxp3 that in turn suppressed IL-9 production. In an allergic airway disease model, Tc9 cells promoted the onset of airway inflammation, mediated by subpathogenic numbers of Th2 cells. This support was specific for Tc9 cells because CTLs failed to exert this function. We detected increased Tc9 frequency in the periphery in mice and humans with atopic dermatitis, a Th2-associated skin disease that often precedes asthma. Thus, our data point to the existence of Tc9 cells and to their supportive function in Th2-dependent airway inflammation, suggesting that these cells might be a therapeutic target in allergic disorders.

Paraneoplastic and non-paraneoplastic autoimmunity to neurons in the central nervous system

Autoimmune central nervous system (CNS) inflammation occurs both in a paraneoplastic and non-paraneoplastic context. In a widening spectrum of clinical disorders, the underlying adaptive (auto) immune response targets neurons with a divergent role for cellular and humoral disease mechanisms: (1) in encephalitis associated with antibodies to intracellular neuronal antigens, neuronal antigen-specific CD8⁺ T cells seemingly account for irreversible progressive neuronal cell death and neurological decline with poor response to immunotherapy. However, a pathogenic effect of humoral immune mechanisms is also debated. (2) In encephalitis associated with antibodies to synaptic and extrasynaptic neuronal cell surface antigens, potentially reversible antibody-mediated disturbance of synaptic transmission and neuronal excitability occurs in the absence of excessive neuronal damage and accounts for a good response to immunotherapy. However, a pathogenic effect of cellular immune mechanisms is also debated. We provide an overview of entities, clinical hallmarks, imaging features, characteristic laboratory, electrophysiological, cerebrospinal fluid and neuropathological findings, cellular and molecular disease mechanisms as well as therapeutic options in these two broad categories of inflammatory CNS disorders.

Size and dynamics of mucosal and peripheral IL-17A+ T-cell pools in pediatric age, and their disturbance in celiac disease

Mucosal interleukin (IL)-17A-producing T cells contribute to protective antimicrobial responses and to epithelial barrier integrity; their role in celiac disease (CD) is debated. We analyzed the frequency and developmental dynamics of mucosal (intraepithelial lymphocytes (IEL)) and circulating (peripheral blood (PB)) IL-17A (T17) and/or interferon (IFN)-γ-producing (T1, T1/T17) T-cell populations in 86 pediatric controls and 116 age-matched CD patients upon phorbol myristate acetate/ionomycin or CD3/CD28 stimulation. T17 and T1/17 are physiologically present among IEL and PB populations, and their frequency is selectively and significantly reduced in CD IEL. The physiological age-dependent increase of Th17 IEL is also absent in CD, while IFN-γ-producing PB-T cells significantly accumulate with patient's age. Finally, the amplitude of IL-17A+ and IFN-γ+ T-cell pools are significantly correlated in different individuals; this relationship only applies to CD4+ T cells in controls, while it involves also the CD4- counterpart in CD patients. In conclusion, both size and dynamics of mucosa-associated and circulating IL-17A+ T-cell pools are finely regulated in human pediatric subjects, and severely disturbed in CD. The impaired IL-17A+ IEL-T pool may negatively impact on epithelial barrier efficiency, and contribute to CD mucosa damage; the disturbed dynamics of circulating IL-17A+ and IFN-γ+ T-cell pools may be involved in the extraintestinal autoimmune manifestations associated with CD.

The effects of TLR activation on T-cell development and differentiation

Invading pathogens have unique molecular signatures that are recognized by Toll-like receptors (TLRs) resulting in either activation of antigen-presenting cells (APCs) and/or costimulation of T cells inducing both innate and adaptive immunity. TLRs are also involved in T-cell development and can reprogram Treg cells to become helper cells. T cells consist of various subsets, that is, Th1, Th2, Th17, T follicular helper (Tfh), cytotoxic T lymphocytes (CTLs), regulatory T cells (Treg) and these originate from thymic progenitor thymocytes. T-cell receptor (TCR) activation in distinct T-cell subsets with different TLRs results in differing outcomes, for example, activation of TLR4 expressed in T cells promotes suppressive function of regulatory T cells (Treg), while activation of TLR6 expressed in T cells abrogates Treg function. The current state of knowledge of regarding TLR-mediated T-cell development and differentiation is reviewed.

Combined mTOR inhibition and OX40 agonism enhances CD8(+) T cell memory and protective immunity produced by recombinant adenovirus vaccines

The memory CD8(+) T cell population elicited by immunization with recombinant human adenovirus serotype 5 (rHuAd5) vaccines is composed primarily of effector and effector memory cells (T(EM)) with limited polyfunctionality. In this study, we investigated whether treatment with immunomodulators could enhance and/or redistribute the CD8(+) memory population elicited by rHuAd5. Vaccination in combination with both rapamycin (to modulate differentiation) and an OX40 agonist (to enhance costimulation) increased both the quantity and polyfunctionality of the CD8(+) memory T cell population, with expansion of the T(EM) and memory precursor populations. Furthermore, this intervention enhanced protection against multiple virus challenges. Attenuation of adenovirus transgene expression was required to enable the combination rapamycin + OX40 agonist immunomodulatory treatment to further enhance skewing towards central memory formation, indicating that persistence of antigen expression ultimately limits development of this memory population following rHuAd5 immunization. These results demonstrate that during the expansion phase following adenovirus immunization, the level of mammalian target of rapamycin (mTOR) activity, the amount of costimulation and the duration of antigen availability act together to define the magnitude, phenotype, and functionality of memory CD8(+) T cells. Modulation of these factors can be used to selectively manipulate memory formation.

Fish T cells: recent advances through genomics

This brief review is intended to provide a concise overview of the current literature concerning T cells, advances in identifying distinct T cell functional subsets, and in distinguishing effector cells from memory cells. We compare and contrast a wealth of recent progress made in T cell immunology of teleost, elasmobranch, and agnathan fish, to knowledge derived from mammalian T cell studies. From genome studies, fish clearly have most components associated with T cell function and we can speculate on the presence of putative T cell subsets, and the ability to detect their differentiation to form memory cells. Some recombinant proteins for T cell associated cytokines and antibodies for T cell surface receptors have been generated that will facilitate studying the functional roles of teleost T cells during immune responses. Although there is still a long way to go, major advances have occurred in recent years for investigating T cell responses, thus phenotypic and functional characterization is on the near horizon.

IL-17 signaling in host defense against Candida albicans

The discovery of the Th17 lineage in 2005 triggered a major change in how immunity to infectious diseases is viewed. Fungal infections, in particular, have long been a relatively understudied area of investigation in terms of the host immune response. Candida albicans is a commensal yeast that colonizes mucosal sites and skin. In healthy individuals, it is non-pathogenic, but in conditions of immune deficiency, this organism can cause a variety of infections associated with considerable morbidity. Candida can also cause disseminated infections that have a high mortality rate and are a major clinical problem in hospital settings. Although immunity to Candida albicans was long considered to be mediated by Th1 cells, new data in both rodent models and in humans have revealed an essential role for the Th17 lineage, and in particular its signature cytokine IL-17.

Colorectal cancer vaccines in clinical trials

This article elucidates current strategies of active immunotherapy for colorectal cancer patients with a focus on T-cell mediated immunotherapy. Poor prognosis of especially stage III and IV colorectal cancer patients emphasizes the need for advanced therapeutic intervention. Here, we refer to clinical trials using either tumor cell-derived vaccines or tumor antigen vaccines with a special interest on safety, induced immune responses, clinical benefit and efforts to improve the clinical impact of these vaccines in the context of colorectal cancer treatment.

NKG2D receptor regulates human effector T-cell cytokine production

Although innate immune signals shape the activation of naive T cells, it is unclear how innate signals influence effector T-cell function. This study determined the effects of stimulating the NKG2D receptor in conjunction with the TCR on human effector CD8(+) T cells. Stimulation of CD8(+) T cells through CD3 and NKG2D simultaneously or through a chimeric NKG2D receptor, which consists of NKG2D fused to the intracellular region of CD3ζ, activated β-catenin and increased expression of β-catenin-induced genes, whereas T cells stimulated through the TCR or a combination of the TCR and CD28 did not. Activation by TCR and NKG2D prevented expression and production of anti-inflammatory cytokines IL-10, IL-9, IL-13, and VEGF-α in a β-catenin- and PPARγ- dependent manner. NKG2D stimulation also modulated the cytokine secretion of T cells activated simultaneously through CD3 and CD28. These data indicate that activating CD8(+) T cells through the NKG2D receptor along with the TCR modulates signal transduction and the production of anti-inflammatory cytokines. Thus, human effector T cells alter their function depending on which innate receptors are engaged in conjunction with the TCR complex.

Generating diversity: transcriptional regulation of effector and memory CD8 T-cell differentiation

SUMMARY

In response to acute infections or vaccines, naive antigen-specific CD8(+) T cells proliferate and differentiate into effector cytotoxic lymphocytes that acquire the ability to kill infected cells. While the majority of differentiated effector cells die after pathogen clearance, a small number evade terminal differentiation, downregulate active effector functions, and survive as long-lived, self-renewing memory T cells. Our understanding of how effector CD8(+) T cells adopt these different cell fates has grown greatly in recent years. In this review, we discuss the transcriptional regulators that are known to support general effector differentiation, terminal effector differentiation, and memory cell formation. We propose that the diversity of activated CD8(+) T-cell differentiation states is achieved via gradients of activity or expression of transcriptional regulators that are regulated by the level of inflammation and antigenic signaling the T cells experience during infection.