Pluripotent stem cell-derived retinal organoid/cells for retinal regeneration therapies: A review

In recent decades, many researchers have attempted to restore vision via transplantation of retina/retinal cells in eyes with retinal degeneration. The advent of induced pluripotent stem cells (iPSC) and retinal organoid induction technologies has boosted research on retinal regeneration therapy. Although the recognition of functional integration of graft photoreceptor cells in the host retina from 2006 has been disputed a decade later by the newly evidenced phenomenon denoted as "material transfer," several reports support possible reconstruction of the host-graft network in the retinas of both end-stage degeneration and in progressing degeneration cases. Based on proof of concept (POC) studies in animal models, a clinical study was conducted in Kobe, Japan in 2020 and showed the feasibility of cell-based therapy using iPSC retinal organoid technology. Although the graft potency of human embryonic stem (ES)/iPS cell-derived retinal organoid/retinal cells has been suggested by previous studies, much is still unknown regarding host capability, that is, how long-standing human degenerating retinas are capable of rewiring with transplanted cells. This review summarizes past POC studies on photoreceptor replacement therapy and introduces some new challenges to maximize the possible efficacy in future human clinical studies of regenerative therapy.

Identifies microtubule-binding protein CSPP1 as a novel cancer biomarker associated with ferroptosis and tumor microenvironment

Centrosome and spindle pole-associated protein (CSPP1) is a centrosome and microtubule-binding protein that plays a role in cell cycle-dependent cytoskeleton organization and cilia formation. Previous studies have suggested that CSPP1 plays a role in tumorigenesis; however, no pan-cancer analysis has been performed. This study systematically investigates the expression of CSPP1 and its potential clinical outcomes associated with diagnosis, prognosis, and therapy. CSPP1 is widely present in tissues and cells and its aberrant expression serves as a diagnostic biomarker for cancer. CSPP1 dysregulation is driven by multi-dimensional mechanisms involving genetic alterations, DNA methylation, and miRNAs. Phosphorylation of CSPP1 at specific sites may play a role in tumorigenesis. In addition, CSPP1 correlates with clinical features and outcomes in multiple cancers. Take brain low-grade gliomas (LGG) with a poor prognosis as an example, functional enrichment analysis implies that CSPP1 may play a role in ferroptosis and tumor microenvironment (TME), including regulating epithelial-mesenchymal transition, stromal response, and immune response. Further analysis confirms that CSPP1 dysregulates ferroptosis in LGG and other cancers, making it possible for ferroptosis-based drugs to be used in the treatment of these cancers. Importantly, CSPP1-associated tumors are infiltrated in different TMEs, rendering immune checkpoint blockade therapy beneficial for these cancer patients. Our study is the first to demonstrate that CSPP1 is a potential diagnostic and prognostic biomarker associated with ferroptosis and TME, providing a new target for drug therapy and immunotherapy in specific cancers.

Frontiers in Lichen Planopilaris and Frontal Fibrosing Alopecia Research: Pathobiology Progress and Translational Horizons

Lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) are primary, lymphocytic cicatricial hair loss disorders. These model epithelial stem cell (SC) diseases are thought to result from a CD8⁺ T-cell‒dominated immune attack on the hair follicle (HF) SC niche (bulge) after the latter has lost its immune privilege (IP) for as yet unknown reasons. This induces both apoptosis and pathological epithelial‒mesenchymal transition in epithelial SCs, thus depletes the bulge, causes fibrosis, and ultimately abrogates the HFs' capacity to regenerate. In this paper, we synthesize recent progress in LPP and FFA pathobiology research, integrate our limited current understanding of the roles that genetic, hormonal, environmental, and other factors may play, and define major open questions. We propose that LPP and FFA share a common initial pathobiology, which then bifurcates into two distinct clinical phenotypes, with macrophages possibly playing a key role in phenotype determination. As particularly promising translational research avenues toward direly needed progress in the management of these disfiguring, deeply distressful cicatricial alopecia variants, we advocate to focus on the development of bulge IP and epithelial SC protectants such as, for example, topically effective, HF‒penetrating and immunoinhibitory preparations that contain tacrolimus, peroxisome proliferator-activated receptor-γ, and/or CB1 agonists.

TNF-α and IL-1β Do Not Induce Langerhans Cell Migration by Inhibiting TGFβ Activation

In the skin, Langerhans cells (LCs) require autocrine latent TGFβ that is transactivated by the integrins ανβ6 and ανβ8 expressed by keratinocytes (KCs) for long-term epidermal retention. Selective expression of a ligand-independent, constitutively active form of TGFβR1 inhibits LC migration during homeostasis and in response to UVB exposure. In this study, we found that LC migration in response to inflammatory stimuli was also inhibited by ligand-independent TGFβR1 signaling. Contrary to UVB stimulation, which reduced KC expression of ανβ6, in vitro and in vivo exposure to TNF-α or IL-1β increased ανβ6 transcript and protein expression by KCs. This resulted in increased KC-mediated transactivation of latent TGFβ. Expression of ανβ8 was largely unchanged. These findings show that ligand-independent TGFβR1 signaling in LCs can overcome inflammatory migration stimuli, but reduced KC-mediated transactivation of latent TGFβ by KCs may only drive LC migration during homeostasis and in response to UV stimulation.

Multiple autoimmunity and epitope spreading in monozygotic twins

We report clinical, serologic, and immunogenetic studies of a set of monozygotic male twin patients who develop autoimmune thyroiditis and vitiligo associated with the HLA-DRB1*04-DQB1*03:02 and HLA-DRB1*03-DQB1*0201 haplotypes. The patients had detectable anti-thyroid and anti-melanocyte autoantibodies. A critical review is presented regarding the role of MHC II molecules linked to clinical manifestations of various autoimmune diseases displayed in a single patient, as is the case in the twin patients reported here.

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Multiple autoimmunity is a clinicopathological issue that is not well understood.

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Monozygotic twins with thyroiditis, vitiligo, HLA-DRB1*04-DQB1*03:02 and HLA-DRB1*03-DQBI*0201 haplotypes.

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Multiple autoantibodies related with intermolecular epitope spreading. Epitope handling by MHC proteins probably related with multiple autoimmunity.

Monitoring Cellular Movement with Photoconvertible Fluorescent Protein and Single-Cell RNA Sequencing Reveals Cutaneous Group 2 Innate Lymphoid Cell Subtypes, Circulating ILC2 and Skin-Resident ILC2

We previously generated a transgenic mouse line expressing skin-specific IL-33 (IL33tg mice) and showed that IL-33 elicits group 2 innate lymphoid cell (ILC2)-dependent atopic dermatitis-like skin inflammation. ILC2s are believed to be tissue-resident cells under steady-state conditions, but the dynamics of ILC2 migration are not fully understood. We sorted ILC2s from the skin and draining lymph nodes of IL33tg mice and analyzed their transcriptomes using the single-cell RNA sequencing technique, which revealed that the skin ILC2s had split into two clusters: circulating ILC2 and skin-resident ILC2. The circulating ILC2s expressed H2-related major histocompatibility complex class II genes. Conversely, the skin-resident ILC2s demonstrated increased mRNA expression of the ICOS, IL-5, and IL-13. Next, we tracked ILC2 migration using IL33tg-Kikume Green-Red mice. Exposing the IL33tg-Kikume Green-Red mice's inflamed skin to violet light allowed us to label the circulating ILC2s in their skin and track the ILC2 migration from the skin to the draining lymph nodes. Cutaneous local innate responses could transition to systemic type 2 responses by migrating the activated ILC2s from the skin into the draining lymph node. Conversely, the skin-resident ILC2s produced a large number of cytokines. Thus, the skin ILC2s turned out to be a heterogeneous cell population.

Vaccine-induced ErbB (EGFR/HER2)-specific immunity in spontaneous canine cancer

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Spontaneous dog cancers closely resemble human cancer.

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Dogs with EGFR associated tumors were immunized with an EGFR/HER2 peptide vaccine.

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EGFR peptide vaccinated dogs developed anti-EGFR/HER2 antibodies.

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Vaccinated dogs have anti-EGFR antibody and T cells infiltrating tumors.

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Vaccinated dogs with osteosarcoma had tumor regression and increased survival.

Epidermal Growth Factor Receptor (EGFR) is overexpressed on a number of human cancers, and often is indicative of a poor outcome. Treatment of EGFR/HER2 overexpressing cancers includes monoclonal antibody therapy (cetuximab/trastuzumab) either alone or in conjunction with other standard cancer therapies. While monoclonal antibody therapy has been proven to be efficacious in the treatment of EGFR/HER2 overexpressing tumors, drawbacks include the lack of long-lasting immunity and acquired resistance to monoclonal therapy. An alternative approach is to induce a polyclonal anti-EGFR/HER2 tumor antigen response by vaccine therapy. In this phase I/II open-label study, we examined anti-tumor immunity in companion dogs with spontaneous EGFR expressing tumors. Canine cancers represent an outbred population in which the initiation, progression of disease, mutations and growth factors closely resemble that of human cancers. Dogs with EGFR expressing tumors were immunized with a short peptide of the EGFR extracellular domain with sequence homology to HER2. Serial serum analyses demonstrated high titers of EGFR/HER2 binding antibodies with biological activity similar to that of cetuximab and trastuzumab. Canine antibodies bound both canine and human EGFR on tumor cell lines and tumor tissue. CD8 T cells and IgG deposition were evident in tumors from immunized dogs. The antibodies inhibited EGFR intracellular signaling and inhibited tumor growth in vitro. Additionally, we illustrate objective responses in reducing tumors at metastatic sites in host animals. The data support the approach of amplifying anti-tumor immunity that may be relevant in combination with other immune modifying therapies such as checkpoint inhibitors.

Human MAIT cells endowed with HBV specificity are cytotoxic and migrate towards HBV-HCC while retaining antimicrobial functions

BACKGROUND & AIMS

Virus-specific T cell dysfunction is a common feature of HBV-related hepatocellular carcinoma (HBV-HCC). Conventional T (ConT) cells can be redirected towards viral antigens in HBV-HCC when they express an HBV-specific receptor; however, their efficacy can be impaired by liver-specific physical and metabolic features. Mucosal-associated invariant T (MAIT) cells are the most abundant innate-like T cells in the liver and can elicit potent intrahepatic effector functions. Here, we engineered ConT and MAIT cells to kill HBV expressing hepatoma cells and compared their functional properties.

METHODS

Donor-matched ConT and MAIT cells were engineered to express an HBV-specific T cell receptor (TCR). Cytotoxicity and hepatocyte homing potential were investigated using flow cytometry, real-time killing assays, and confocal microscopy in 2D and 3D HBV-HCC cell models. Major histocompatibility complex (MHC) class I-related molecule (MR1)-dependent and MR1-independent activation was evaluated in an Escherichia coli THP-1 cell model and by IL-12/IL-18 stimulation, respectively.

RESULTS

HBV TCR-MAIT cells demonstrated polyfunctional properties (CD107a, interferon [IFN] γ, tumour necrosis factor [TNF], and IL-17A) with strong HBV target sensitivity and liver-homing chemokine receptor expression when compared with HBV TCR-ConT cells. TCR-mediated lysis of hepatoma cells was comparable between the cell types and augmented in the presence of inflammation. Coculturing with HBV+ target cells in a 3D microdevice mimicking aspects of the liver microenvironment demonstrated that TCR-MAIT cells migrate readily towards hepatoma targets. Expression of an ectopic TCR did not affect the ability of the MAIT cells to be activated via MR1-presented bacterial antigens or IL-12/IL-18 stimulation.

CONCLUSIONS

HBV TCR-MAIT cells demonstrate anti-HBV functions without losing their endogenous antimicrobial mechanisms or hepatotropic features. Our results support future exploitations of MAIT cells for liver-directed immunotherapies.

LAY SUMMARY

Chronic HBV infection is a leading cause of liver cancer. T cell receptor (TCR)-engineered T cells are patients' immune cells that have been modified to recognise virus-infected and/or cancer cells. Herein, we evaluated whether mucosal-associated invariant T cells, a large population of unconventional T cells in the liver, could recognise and kill HBV infected hepatocytes when engineered with an HBV-specific TCR. We show that their effector functions may exceed those of conventional T cells currently used in the clinic, including antimicrobial properties and chemokine receptor profiles better suited for targeting liver tumours.

The role of cGAS-STING signalling in liver diseases

The recently identified novel cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) activates the downstream adaptor protein stimulator of interferon genes (STING) by catalysing the synthesis of cyclic GMP-AMP. This in turn initiates an innate immune response through the release of various cytokines, including type I interferon. Foreign DNA (microbial infection) or endogenous DNA (nuclear or mitochondrial leakage) can serve as cGAS ligands and lead to the activation of cGAS-STING signalling. Therefore, the cGAS-STING pathway plays essential roles in infectious diseases, sterile inflammation, tumours, and autoimmune diseases. In addition, cGAS-STING signalling affects the progression of liver inflammation through other mechanisms, such as autophagy and metabolism. In this review, we summarise recent advances in our understanding of the role of cGAS-STING signalling in the innate immune modulation of different liver diseases. Furthermore, we discuss the therapeutic potential of targeting the cGAS-STING pathway in the treatment of liver diseases.

Extracellular vesicle activities regulating macrophage- and tissue-mediated injury and repair responses

Macrophages are typically identified as classically activated (M1) macrophages and alternatively activated (M2) macrophages, which respectively exhibit pro- and anti-inflammatory phenotypes, and the balance between these two subtypes plays a critical role in the regulation of tissue inflammation, injury, and repair processes. Recent studies indicate that tissue cells and macrophages interact via the release of small extracellular vesicles (EVs) in processes where EVs released by stressed tissue cells can promote the activation and polarization of adjacent macrophages which can in turn release EVs and factors that can promote cell stress and tissue inflammation and injury, and vice versa. This review discusses the roles of such EVs in regulating such interactions to influence tissue inflammation and injury in a number of acute and chronic inflammatory disease conditions, and the potential applications, advantage and concerns for using EV-based therapeutic approaches to treat such conditions, including their potential role of drug carriers for the treatment of infectious diseases.

Selective Interleukin-6 Trans-Signaling Blockade Is More Effective Than Panantagonism in Reperfused Myocardial Infarction

Interleukin (IL)-6 is an emerging therapeutic target in myocardial infarction (MI). IL-6 has 2 distinct signaling pathways: trans-signaling, which mediates inflammation, and classic signaling, which also has anti-inflammatory effects. The novel recombinant fusion protein sgp130Fc achieves exclusive trans-signaling blockade, whereas anti-IL-6 antibodies (Abs) result in panantagonism. In a rat model of reperfused MI, sgp130Fc, but not anti-IL-6-Ab, attenuated neutrophil and macrophage infiltration into the myocardium, reduced infarct size, and preserved cardiac function 28 days after MI. These data demonstrate the efficacy of exclusive IL-6 trans-signaling blockade and support further investigation of sgp130Fc as a potential novel therapy in MI.

A novel therapeutic HBV vaccine candidate induces strong polyfunctional cytotoxic T cell responses in mice

Background & Aims

Current standard-of-care suppresses HBV replication, but does not lead to a functional cure. Treatment aiming to cure chronic hepatitis B (CHB) is believed to require the induction of strong cellular immune responses, such as by therapeutic vaccination.

Methods

We designed a therapeutic HBV vaccine candidate (YF17D/HBc-C) using yellow fever vaccine YF17D as a live-attenuated vector to express HBV core antigen (HBc). Its ability to induce potent cellular immune responses was assessed in a mouse model that supports flavivirus replication.

Results

Following a HBc protein prime, a booster of YF17D/HBc-C was found to induce vigorous cytotoxic T cell responses. In a direct head-to-head comparison, these HBc-specific responses exceeded those elicited by adenovirus-vectored HBc. Target-specific T cells were not only more abundant, but also showed a higher degree of polyfunctionality, with HBc-specific CD8⁺ T cells producing interferon γ and tumour necrosis factor α in addition to granzyme B. This immune phenotype translated into a superior cytotoxic effector activity toward HBc-positive cells in YF17D/HBc-C vaccinated animals in vivo.

Conclusions

The results presented here show the potential of YF17D/HBc-C as a vaccine candidate to treat CHB, and warrant follow-up studies in preclinical animal models of HBV persistence in which other candidate vaccines have been unable to achieve a sustained virologic response.

Lay summary

Resolution of CHB requires the induction of strong cellular immune responses. We used the yellow fever vaccine as a vector for HBV antigens and show that it is capable of inducing high levels of HBV-specific T cells that produce multiple cytokines simultaneously and are cytotoxic in vivo.

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Resolution of CHB requires the induction of vigorous cellular immune responses.

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Yellow fever vaccine (YF17D) is safe, and can serve as potent viral vector for foreign antigens.

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HBc is a relevant therapeutic target in CHB.

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YF17D-vectored HBc might elicit more potent and particularly polyfunctional T cell responses compared with other vaccine modalities.

Immune evasion by cancer stem cells

Tumor immunity represents a new avenue for cancer therapy. Immune checkpoint inhibitors have successfully improved outcomes in several tumor types. In addition, currently, immune cell-based therapy is also attracting significant attention. However, the clinical efficacy of these treatments requires further improvement. The mechanisms through which cancer cells escape the immune response must be identified and clarified. Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors. CSCs can initiate tumors in partially immunocompromised mice, whereas non-CSCs fail to form tumors, suggesting that tumor initiation is a definitive function of CSCs. However, the fact that non-CSCs also initiate tumors in more highly immunocompromised mice suggests that the immune evasion property may be a more fundamental feature of CSCs rather than a tumor-initiating property. In this review, we summarize studies that have elucidated how CSCs evade tumor immunity and create an immunosuppressive milieu with a focus on CSC-specific characteristics and functions. These profound mechanisms provide important clues for the development of novel tumor immunotherapies.

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Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors.

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Immune evasion is a fundamental feature of CSCs.

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Immune evasion mechanisms must be precisely clarified to improve tumor immunotherapy.

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CSCs are promising targets for tumor immunotherapy.

In vitro and ex vitro functional characterization of human HLA-DRB1∗04 restricted T cell receptors

Recent advances in single-cell sequencing technologies enable the generation of large-scale data sets of paired TCR sequences from patients with autoimmune disease. Methods to validate and characterize patient-derived TCR data are needed, as well as relevant model systems that can support the development of antigen-specific tolerance inducing drugs. We have generated a pipeline to allow streamlined generation of 'artificial' T cells in a robust and reasonably high throughput manner for in vitro and in vivo studies of antigen-specific and patient-derived immune responses. Hereby chimeric (mouse-human) TCR alpha and beta constructs are re-expressed in three different formats for further studies: (i) transiently in HEK cells for peptide-HLA tetramer validation experiments, (ii) stably in the TCR-negative 58 ​T cell line for functional readouts such as IL-2 production and NFAT-signaling, and lastly (iii) in human HLA-transgenic mice for studies of autoimmune disease and therapeutic interventions. As a proof of concept, we have used human HLA-DRB1∗04:01 restricted TCR sequences specific for a type I diabetes-associated GAD peptide, and an influenza-derived HA peptide. We show that the same chimeric TCR constructs can be used in each of the described assays facilitating sequential validation and prioritization steps leading to humanized animal models.

Inflammatory Mediators in Glioma Microenvironment Play a Dual Role in Gliomagenesis and Mesenchymal Stem Cell Homing: Implication for Cellular Therapy

Glioblastoma is the most aggressive malignant primary brain tumor, with a dismal prognosis and a devastating overall survival. Despite aggressive surgical resection and adjuvant treatment, average survival remains approximately 14.6 months. The brain tumor microenvironment is heterogeneous, comprising multiple populations of tumor, stromal, and immune cells. Tumor cells evade the immune system by suppressing several immune functions to enable survival. Gliomas release immunosuppressive and tumor-supportive soluble factors into the microenvironment, leading to accelerated cancer proliferation, invasion, and immune escape. Mesenchymal stem cells (MSCs) isolated from bone marrow, adipose tissue, or umbilical cord are a promising tool for cell-based therapies. One crucial mechanism mediating the therapeutic outcomes often seen in MSC application is their tropism to sites of injury. Furthermore, MSCs interact with host immune cells to regulate the inflammatory response, and data points to the possibility of using MSCs to achieve immunomodulation in solid tumors. Interleukin 1β, interleukin 6, tumor necrosis factor α, transforming growth factor β, and stromal cell-derived factor 1 are notably up-regulated in glioblastoma and dually promote immune and MSC trafficking. Mesenchymal stem cells have widely been regarded as hypoimmunogenic, enabling this cell-based administration across major histocompatibility barriers. In this review, we will highlight (1) the bidirectional communication of glioma cells and tumor-associated immune cells, (2) the inflammatory mediators enabling leukocytes and transplantable MSC migration, and (3) review preclinical and human clinical trials using MSCs as delivery vehicles. Mesenchymal stem cells possess innate abilities to migrate great distances, cross the blood-brain barrier, and communicate with surrounding cells, all of which make them desirable "Trojan horses" for brain cancer therapy.

Identification of Tumor Antigens in the HLA Peptidome of Patient-derived Xenograft Tumors in Mouse

Personalized cancer immunotherapy targeting patient-specific cancer/testis antigens (CTA) and neoantigens may benefit from large-scale tumor human leukocyte antigen (HLA) peptidome (immunopeptidome) analysis, which aims to accurately identify antigens presented by tumor cells. Although significant efforts have been invested in analyzing the HLA peptidomes of fresh tumors, it is often impossible to obtain sufficient volumes of tumor tissues for comprehensive HLA peptidome characterization. This work attempted to overcome some of these obstacles by using patient-derived xenograft tumors (PDX) in mice as the tissue sources for HLA peptidome analysis. PDX tumors provide a proxy for the expansion of the patient tumor by re-grafting them through several passages to immune-compromised mice. The HLA peptidomes of human biopsies were compared with those derived from PDX tumors. Larger HLA peptidomes were obtained from the significantly larger PDX tumors as compared with the patient biopsies. The HLA peptidomes of different PDX tumors derived from the same source tumor biopsy were very reproducible, even following subsequent passages to new naïve mice. Many CTA-derived HLA peptides were discovered, as well as several potential neoantigens/variant sequences. Taken together, the use of PDX tumors for HLA peptidome analysis serves as a highly expandable and stable source of reproducible and authentic peptidomes, opening up new opportunities for defining large HLA peptidomes when only small tumor biopsies are available. This approach provides a large source for tumor antigens identification, potentially useful for personalized immunotherapy.

Purinergic signalling in liver diseases: Pathological functions and therapeutic opportunities

Extracellular nucleotides, including ATP, are essential regulators of liver function and serve as danger signals that trigger inflammation upon injury. Ectonucleotidases, which are expressed by liver-resident cells and recruited immune cells sequentially hydrolyse nucleotides to adenosine. The nucleotide/nucleoside balance orchestrates liver homeostasis, tissue repair, and functional restoration by regulating the crosstalk between liver-resident cells and recruited immune cells. In this review, we discuss our current knowledge on the role of purinergic signals in liver homeostasis, restriction of inflammation, stimulation of liver regeneration, modulation of fibrogenesis, and regulation of carcinogenesis. Moreover, we discuss potential targeted therapeutic strategies for liver diseases based on purinergic signals involving blockade of nucleotide receptors, enhancement of ectonucleoside triphosphate diphosphohydrolase activity, and activation of adenosine receptors.

Epigenetic strategies synergize with PD-L1/PD-1 targeted cancer immunotherapies to enhance antitumor responses

Immunotherapy strategies targeting the programmed cell death ligand 1 (PD-L1)/programmed cell death 1 (PD-1) pathway in clinical treatments have achieved remarkable success in treating multiple types of cancer. However, owing to the heterogeneity of tumors and individual immune systems, PD-L1/PD-1 blockade still shows slow response rates in controlling malignancies in many patients. Accumulating evidence has shown that an effective response to anti-PD-L1/anti-PD-1 therapy requires establishing an integrated immune cycle. Damage in any step of the immune cycle is one of the most important causes of immunotherapy failure. Impairments in the immune cycle can be restored by epigenetic modification, including reprogramming the environment of tumor-associated immunity, eliciting an immune response by increasing the presentation of tumor antigens, and by regulating T cell trafficking and reactivation. Thus, a rational combination of PD-L1/PD-1 blockade and epigenetic agents may offer great potential to retrain the immune system and to improve clinical outcomes of checkpoint blockade therapy.

Polymyositis and dermatomyositis - challenges in diagnosis and management

Polymyositis (PM) and dermatomyositis (DM) are different disease subtypes of idiopathic inflammatory myopathies (IIMs). The main clinical features of PM and DM include progressive symmetric, predominantly proximal muscle weakness. Laboratory findings include elevated creatine kinase (CK), autoantibodies in serum, and inflammatory infiltrates in muscle biopsy. Dermatomyositis can also involve a characteristic skin rash. Both polymyositis and dermatomyositis can present with extramuscular involvement. The causative factor is agnogenic activation of immune system, leading to immunologic attacks on muscle fibers and endomysial capillaries. The treatment of choice is immunosuppression. PM and DM can be distinguished from other IIMs and myopathies by thorough history, physical examinations and laboratory evaluation and adherence to specific and up-to-date diagnosis criteria and classification standards. Treatment is based on correct diagnosis of these conditions.

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Challenges of diagnosis and management influences the clinical research and practice of Polymyositis and dermatomyositis.

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Diagnostic criteria have been updated and novel therapies have been developed in PM/DM.

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Pathogenesis investigation and diagnosis precision improvement may help to guide future treatment strategies.

Characterization of the Myocardial Inflammatory Response in Acute Stress-Induced (Takotsubo) Cardiomyopathy

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Takotsubo cardiomyopathy is an acute heart failure syndrome often triggered by emotional or physical stress, where no treatment currently exists, and exact pathogenic mechanisms are unclear.

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Rats in which takotsubo-like cardiomyopathy was induced showed localized myocardial inflammatory changes, including progressive inflammatory infiltrates and myofiber atrophy, that persisted over the 14-day time course examined.

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Early neutrophil infiltrates were followed by clusters of myocardial macrophages, typically of an M1 proinflammatory phenotype, with no switch to M2 resolving macrophages; individual M2 macrophage levels, however, correlated with recovery in cardiac function. Human post-mortem myocardial tissue shared features of the experimental model demonstrating M1 macrophage clusters.

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The persistent clinical symptoms and long-term morbidity/mortality observed in takotsubo patients may, in part, relate to chronic nonresolving myocardial inflammation.

Takotsubo cardiomyopathy is an acute stress-induced heart failure syndrome for which the exact pathogenic mechanisms are unclear, and consequently, no specific treatment exists. In an experimental model of stress-induced takotsubo-like cardiomyopathy, the authors describe the temporal course of a chronic inflammatory response post-induction, with an initial early influx of neutrophils into myocardial tissue followed by macrophages that are typical of a proinflammatory M1 phenotype, and a nonsignificant increase in systemic inflammatory cytokines. Post-mortem myocardium from the more complex clinical takotsubo patients share features of the study’s experimental model. These findings suggest modulators of inflammation could be a potential therapeutic option.

The transcriptional response of mouse spleen B cells to IL-4: Comparison to the response of human peripheral blood B cells

The Th2 cytokine IL-4 triggers a signaling cascade which activates transcription by STAT6. The goals of the present study are to define the transcriptomic response of mouse spleen B cells (mSBC) to IL-4 used as single stimulus, its specificity compared to human peripheral blood B cells (hPBBC) and to mouse spleen T cells (mSTC), and the pathways affected. Oligonucleotide-based microarrays were performed using two references, the untreated sample and the cells cultured without IL-4, an experimental design which reduces the potential confounding effect of cellular stress during culture. Specificity was addressed by comparing the response of mSBC and our previously published study on hPBBC, of similar design, and a study by other authors on mSTC. We detected an mSBC-specific response (including novel genes, e.g., Sertad4, Lifr, Pmepa1, Epcam, Tbxas1; and common genes, e.g., Usp2, Cst7, Grtp1, and Casp6), an hPBBC-specific response (e.g., CCL17, MTCL1, GCSAM, HOMER2, IL2RA), and a common mSBC/hPBBC response (e.g., CISH, NFIL3, SOCS1, VDR, CDH1). In contrast, the mSBC and mSTC responses were largely divergent. Gene set enrichment analysis (GSEA) was applied for the first time to identify the pathways affected. Both in mSBC and hPBBC, IL-4 activated Myc, the transcriptional machinery itself, cell cycle, mitochondria and respiratory chain, ribosome, proteasome and antigen presentation, and Wnt signaling, and inhibited GPCR signaling. However, significant differences were found in histone demethylation, Nod signaling, and Rho signaling, which were downregulated in mSBC, and in chromatin condensation, which was downregulated in hPBBC. These findings may have therapeutic implications for the treatment of allergic diseases and parasitic infections.

Biomimetic nanoparticles for inflammation targeting

There have been many recent exciting developments in biomimetic nanoparticles for biomedical applications. Inflammation, a protective response involving immune cells, blood vessels, and molecular mediators directed against harmful stimuli, is closely associated with many human diseases. As a result, biomimetic nanoparticles mimicking immune cells can help achieve molecular imaging and precise drug delivery to these inflammatory sites. This review is focused on inflammation-targeting biomimetic nanoparticles and will provide an in-depth look at the design of these nanoparticles to maximize their benefits for disease diagnosis and treatment.

Acute and Chronic Rejection After Liver Transplantation: What A Clinician Needs to Know

While antibody mediated hyper-acute vasculitic rejection is rare in liver transplant recipients, acute and chronic rejection have clinical significance. The liver allograft behaves differently to other solid organ transplants as acute rejection generally does not impair graft survival and chronic rejection (CR) is uncommon. The incidence of acute and chronic rejection has declined in current era due to improved immunosuppressive regimens. Acute rejection generally improves with steroid boluses and steroid resistant rejection is uncommon. CR may improve with escalation of immunosuppression or may result in irreversible loss of graft function leading to retransplantation or death. The current review discusses diagnosis and management of acute and chronic liver allograft rejection.

Protease activity of legumain is inhibited by an increase of cystatin E/M in the DJ-1-knockout mouse spleen, cerebrum and heart

Legumain (EC 3.4.22.34) is an asparaginyl endopeptidase. Legumain activity has been detected in various mouse tissues including the kidney, spleen and epididymis. Legumain is overexpressed in the majority of human solid tumors and transcription of the legumain gene is regulated by the p53 tumor suppressor in HCT116 cells. The legumain activity is also increased under acid conditions in Alzheimer's disease brains. DJ-1/PARK7, a cancer- and Parkinson's disease-associated protein, works as a coactivator to various transcription factors, including the androgen receptor, p53, PSF, Nrf2, SREBP and RREB1. Recently, we found that legumain expression, activation and cleavage of annexin A2 are regulated by DJ-1 through p53. In this study, we found that the expression levels of legumain mRNA were increased in the cerebrum, kidney, spleen, heart, lung, epididymis, stomach, small intestine and pancreas from DJ-1-knockout mice, although legumain activity levels were decreased in the cerebrum, spleen and heart from DJ-1-knockout mice. Furthermore, we found that cystatin E/M expression was increased in the spleen, cerebrum and heart from DJ-1-knockout mice. These results suggest that reduction of legumain activity is caused by an increase of cystatin E/M expression in the spleen, cerebrum and heart from DJ-1-knockout mice.

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Legumain is strongly activated in the epididymis from DJ-1-knockout mice.

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Expression level of legumain mRNA is increased but activity is decreased in the spleen, cerebrum and heart from DJ-1-knockout mice.

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Expression level of cystatin E/M is increased in the spleen, cerebrum and heart from DJ-1-knockout mice.

Primary Biliary Cholangitis: Disease Pathogenesis and Implications for Established and Novel Therapeutics

Primary Biliary Cholangitis is a progressive, autoimmune cholestatic liver disorder. Cholestasis with disease progression may lead to dyslipidemia, osteodystrophy and fat-soluble vitamin deficiency. Portal hypertension may develop prior to advanced stages of fibrosis. Untreated disease may lead to cirrhosis, hepatocellular cancer and need for orthotopic liver transplantation. Classically, diagnosis is made with elevation of alkaline phosphatase, demonstration of circulating antimitochondrial antibody, and if performed: asymmetric destruction/nonsupperative cholangitis of intralobular bile ducts on biopsy. Disease pathogenesis is complex and results from innate and adaptive (cell-mediated and humoral) responses that lead to inflammation of biliary duct epithelium. Ongoing damage is amplified and sustained through bile acid toxicity. Use of weight based (13-15mg/kg) ursodeoxycholic acid is well established in retarding disease progression and improving survival; however, is ineffective in achieving complete biochemical remission in many. Recently, a Farnesoid X Receptor agonist, obeticholic acid, has been approved for use. A number of ongoing clinical studies are underway to evaluate utility of fibric acid derivatives, biologics, antifibrotics, and stem cells as monotherapy or in combination with ursodeoxycholic acid for primary biliary cholangitis. The aim of this review is to discuss disease pathogenesis and highlight rationale/implications for both established and novel therapeutics.

Exosomes as therapeutic drug carriers and delivery vehicles across biological membranes: current perspectives and future challenges

Exosomes are small intracellular membrane-based vesicles with different compositions that are involved in several biological and pathological processes. The exploitation of exosomes as drug delivery vehicles offers important advantages compared to other nanoparticulate drug delivery systems such as liposomes and polymeric nanoparticles; exosomes are non-immunogenic in nature due to similar composition as body׳s own cells. In this article, the origin and structure of exosomes as well as their biological functions are outlined. We will then focus on specific applications of exosomes as drug delivery systems in pharmaceutical drug development. An overview of the advantages and challenges faced when using exosomes as a pharmaceutical drug delivery vehicles will also be discussed.

A new TLR2 agonist promotes cross-presentation by mouse and human antigen presenting cells

Cross-presentation is the process by which professional APCs load peptides from an extracellularly derived protein onto class I MHC molecules to trigger a CD8(+) T cell response. The ability to enhance this process is therefore relevant for the development of antitumor and antiviral vaccines. We investigated a new TLR2-based adjuvant, Small Molecule Immune Potentiator (SMIP) 2.1, for its ability to stimulate cross-presentation. Using OVA as model antigen, we demonstrated that a SMIP2.1-adjuvanted vaccine formulation induced a greater CD8(+) T cell response, in terms of proliferation, cytokine production and cytolytic activity, than a non-adjuvanted vaccine. Moreover, using an OVA-expressing tumor model, we showed that the CTLs induced by the SMIP2.1 formulated vaccine inhibits tumor growth in vivo. Using a BCR transgenic mouse model we found that B cells could cross-present the OVA antigen when stimulated with SMIP2.1. We also used a flow cytometry assay to detect activation of human CD8(+) T cells isolated from human PBMCs of cytomegalovirus-seropositive donors. Stimulation with SMIP2.1 increased the capacity of human APCs, pulsed in vitro with the pp65 CMV protein, to activate CMV-specific CD8(+) T cells. Therefore, vaccination with an exogenous antigen formulated with SMIP2.1 is a successful strategy for the induction of a cytotoxic T cell response along with antibody production.

Enhancement of antitumor effect by peptide vaccine therapy in combination with anti-CD4 antibody: Study in a murine model

Purpose

The clinical efficacy of cancer peptide vaccine therapy is insufficient. To enhance the anti-tumor effect of peptide vaccine therapy, we combined this therapy with an anti-CD4 mAb (GK1.5), which is known to deplete CD4⁺ cells, including regulatory T cells (Tregs).

Methods

To determine the treatment schedule, the number of lymphocyte subsets in the peripheral blood of mice was traced by flow cytometry after administration of anti-CD4 mAb. The ovalbumin (OVA)_257–264 peptide vaccine was injected intradermally and anti-CD4 mAb was administered intraperitoneally into C57BL/6 mice at different schedules. We evaluated the enhancement of OVA peptide-specific cytotoxic T lymphocyte (CTL) induction in the combination therapy using the ELISPOT assay, CD107a assay, and cytokine assay. We then examined the in vivo metastasis inhibitory effect by OVA peptide vaccine therapy in combination with anti-CD4 mAb against OVA-expressing thymoma (EG7) in a murine liver metastatic model.

Results

We showed that peptide-specific CTL induction was enhanced by the peptide vaccine in combination with anti-CD4 mAb and that the optimized treatment schedule had the strongest induction effect of peptide-specific CTLs using an IFN-γ ELISPOT assay. We also confirmed that the CD107a⁺ cells secreted perforin and granzyme B and the amount of IL-2 and TNF produced by these CTLs increased when the peptide vaccine was combined with anti-CD4 mAb. Furthermore, metastasis was inhibited by peptide vaccines in combination with anti-CD4 mAb compared to peptide vaccine alone in a murine liver metastatic model.

Conclusion

The use of anti-CD4 mAb in combination with the OVA peptide vaccine therapy increased the number of peptide-specific CTLs and showed a higher therapeutic effect against OVA-expressing tumors. The combination with anti-CD4 mAb may provide a new cancer vaccine strategy.

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Peptide-specific CTL induction and function were enhanced by depletion of CD4⁺ cells.

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Anti-tumor effect by the peptide vaccine was enhanced by the depletion of CD4⁺ cells.

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Metastasis was inhibited by vaccine with depletion of CD4⁺ cells in a murine model.

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Combination with the depletion of CD4⁺ cells could be a new cancer vaccine strategy.

Clinically feasible approaches to potentiating cancer cell-based immunotherapies

The immune system exerts both tumor-destructive and tumor-protective functions. Mature dendritic cells (DCs), classically activated macrophages (M1), granulocytes, B lymphocytes, aβ and ɣδ T lymphocytes, natural killer T (NKT) cells, and natural killer (NK) cells may be implicated in antitumor immunoprotection. Conversely, tolerogenic DCs, alternatively activated macrophages (M2), myeloid-derived suppressor cells (MDSCs), and regulatory T (Tregs) and B cells (Bregs) are capable of suppressing antitumor immune responses. Anti-cancer vaccination is a useful strategy to elicit antitumor immune responses, while overcoming immunosuppressive mechanisms. Whole tumor cells or lysates derived thereof hold more promise as cancer vaccines than individual tumor-associated antigens (TAAs), because vaccinal cells can elicit immune responses to multiple TAAs. Cancer cell-based vaccines can be autologous, allogeneic or xenogeneic. Clinical use of xenogeneic vaccines is advantageous in that they can be most effective in breaking the preexisting immune tolerance to TAAs. To potentiate immunotherapy, vaccinations can be combined with other modalities that target different immune pathways. These modalities include 1) genetic or chemical modification of cell-based vaccines; 2) cross-priming TAAs to T cells by engaging dendritic cells; 3) T-cell adoptive therapy; 4) stimulation of cytotoxic inflammation by non-specific immunomodulators, toll-like receptor (TLR) agonists, cytokines, chemokines or hormones; 5) reduction of immunosuppression and/or stimulation of antitumor effector cells using antibodies, small molecules; and 6) various cytoreductive modalities. The authors envisage that combined immunotherapeutic strategies will allow for substantial improvements in clinical outcomes in the near future.

Functional Specialty of CD40 and Dendritic Cell Surface Lectins for Exogenous Antigen Presentation to CD8(+) and CD4(+) T Cells

Dendritic cells (DCs) are major antigen-presenting cells that can efficiently prime and cross-prime antigen-specific T cells. Delivering antigen to DCs via surface receptors is thus an appealing strategy to evoke cellular immunity. Nonetheless, which DC surface receptor to target to yield the optimal CD8⁺ and CD4⁺ T cell responses remains elusive. Herein, we report the superiority of CD40 over 9 different lectins and scavenger receptors at evoking antigen-specific CD8⁺ T cell responses. However, lectins (e.g., LOX-1 and Dectin-1) were more efficient than CD40 at eliciting CD4⁺ T cell responses. Common and distinct patterns of subcellular and intracellular localization of receptor-bound αCD40, αLOX-1 and αDectin-1 further support their functional specialization at enhancing antigen presentation to either CD8⁺ or CD4⁺ T cells. Lastly, we demonstrate that antigen targeting to CD40 can evoke potent antigen-specific CD8⁺ T cell responses in human CD40 transgenic mice. This study provides fundamental information for the rational design of vaccines against cancers and viral infections.

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Antigen delivery to DCs via CD40 is more efficient than through nine other receptors at eliciting CD8 T⁺ cell response.

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Antigen delivery via lectins (e.g., LOX-1 and Dectin-1) is more efficient than CD40 at eliciting CD4⁺ T cell responses.

The success of an immunotherapeutic vaccine for cancer is largely dependent on its ability to evoke potent cellular immunity. Although targeting antigens to dendritic cells (DCs) has been known to be an efficient strategy to evoke cellular immunity, which targeted receptors yield the optimal cellular immunity remained elusive. We report that targeting CD40, compared to 9 other DC receptors, results in the greatest levels of CD8⁺ cytotoxic T cell responses, while targeting lectins results in enhanced CD4⁺ helper T cell responses. The findings of this study will assist us in the rational design of immunotherapeutic vaccines against cancers.

Apoptotic-like Leishmania exploit the host's autophagy machinery to reduce T-cell-mediated parasite elimination

Apoptosis is a well-defined cellular process in which a cell dies, characterized by cell shrinkage and DNA fragmentation. In parasites like Leishmania, the process of apoptosis-like cell death has been described. Moreover upon infection, the apoptotic-like population is essential for disease development, in part by silencing host phagocytes. Nevertheless, the exact mechanism of how apoptosis in unicellular organisms may support infectivity remains unclear. Therefore we investigated the fate of apoptotic-like Leishmania parasites in human host macrophages. Our data showed—in contrast to viable parasites—that apoptotic-like parasites enter an LC3⁺, autophagy-like compartment. The compartment was found to consist of a single lipid bilayer, typical for LC3-associated phagocytosis (LAP). As LAP can provoke anti-inflammatory responses and autophagy modulates antigen presentation, we analyzed how the presence of apoptotic-like parasites affected the adaptive immune response. Macrophages infected with viable Leishmania induced proliferation of CD4⁺ T-cells, leading to a reduced intracellular parasite survival. Remarkably, the presence of apoptotic-like parasites in the inoculum significantly reduced T-cell proliferation. Chemical induction of autophagy in human monocyte-derived macrophage (hMDM), infected with viable parasites only, had an even stronger proliferation-reducing effect, indicating that host cell autophagy and not parasite viability limits the T-cell response and enhances parasite survival. Concluding, our data suggest that apoptotic-like Leishmania hijack the host cells´ autophagy machinery to reduce T-cell proliferation. Furthermore, the overall population survival is guaranteed, explaining the benefit of apoptosis-like cell death in a single-celled parasite and defining the host autophagy pathway as a potential therapeutic target in treating Leishmaniasis.

In silico design of a DNA-based HIV-1 multi-epitope vaccine for Chinese populations

The development of an HIV-1 vaccine that is capable of inducing effective and broadly cross-reactive humoral and cellular immune responses remains a challenging task because of the extensive diversity of HIV-1, the difference of virus subtypes (clades) in different geographical regions, and the polymorphism of human leukocyte antigens (HLA). We performed an in silico design of 3 DNA vaccines, designated pJW4303-MEG1, pJW4303-MEG2 and pJW4303-MEG3, encoding multi-epitopes that are highly conserved within the HIV-1 subtypes most prevalent in China and can be recognized through HLA alleles dominant in China. The pJW4303-MEG1-encoded protein consisted of one Th epitope in Env, and one, 2, and 6 epitopes in Pol, Env, and Gag proteins, respectively, with a GGGS linker sequence between epitopes. The pJW4303-MEG2-encoded protein contained similar epitopes in a different order, but with the same linker as pJW4303-MEG1. The pJW4303-MEG3-encoded protein contained the same epitopes in the same order as that of pJW4303-MEG2, but with a different linker sequence (AAY). To evaluate immunogenicity, mice were immunized intramuscularly with these DNA vaccines. Both pJW4303-MEG1 and pJW4303-MEG2 vaccines induced equally potent humoral and cellular immune responses in the vaccinated mice, while pJW4303-MEG3 did not induce immune responses. These results indicate that both epitope and linker sequences are important in designing effective epitope-based vaccines against HIV-1 and other viruses.

Collagen Specific T-Cell Repertoire and HLA-DR Alleles: Biomarkers of Active Refractory Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by chronic joint inflammation and associates with HLA-DRB1*04. The Collagen IIp_261-273-specific T cell repertoire in the peripheral blood of DR4 + patients at the onset of the disease shows a restricted TCR-beta chain usage among which the most frequent is TRBV25.

To define whether this group of DR4-restricted collagen-specific shared T cell could represent markers of active-severe disease and response to therapy, 90 subjects affected by early-RA were enrolled in the study; peripheral blood mononuclear cells were cultured with or without the human collagen II peptide p261-273 and were examined by immunoscope analysis for the usage of the previously identified shared TCR-beta chains.

We report that the presence of T cells carrying rearrangement TRBV25 associated with HLA-DR haplotype and disease activity. HLA-DRB1* haplotypes 04–04, 04–01 and 04–11 were significantly associated with usage of TRBV25, higher disease activity at the onset of disease and poor response to DMARDs.

Finally, the HLA-DRB1* haplotype appeared complementary with current serologic tools to predict good and poor responders in a treat to target strategy. The data reported here offer clues to predict the course of the disease and to foresee personalized treatments in RA patients.

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In DR4 + RA patients disease activity is associated with detection of Collagen_261-273-specific T cells carrying TRBV25.

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HLA-DR 04/04, 04/01 and 04/11 alleles were associated with TRBV25, DAS at the onset, and poor response to DMARDs.

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These findings could lead to tailor the treatment in the subgroup of patients with an active refractory disease.

In the era of costly medical care with monoclonal antibodies and new molecules, and of an increasing request of a personalized medicine, a relevant socio-economic problem in the management of Rheumatoid Arthritis patients is the possible identification of the subgroups of poor responders to treatment. Our study aimed to detect the refractory active patients using an HLA-DR test (available in most hospital centers) combined with a relatively new biomarker of active disease expressed on the cell surface of autoreactive T cells. These tests appear complementary tools to identify the best and the poor responders to a “treat to target strategy”.

DNA vaccine for cancer immunotherapy

DNA vaccination has emerged as an attractive immunotherapeutic approach against cancer due to its simplicity, stability, and safety. Results from numerous clinical trials have demonstrated that DNA vaccines are well tolerated by patients and do not trigger major adverse effects. DNA vaccines are also very cost effective and can be administered repeatedly for long-term protection. Despite all the practical advantages, DNA vaccines face challenges in inducing potent antigen specific cellular immune responses as a result of immune tolerance against endogenous self-antigens in tumors. Strategies to enhance immunogenicity of DNA vaccines against self-antigens have been investigated including encoding of xenogeneic versions of antigens, fusion of antigens to molecules that activate T cells or trigger associative recognition, priming with DNA vectors followed by boosting with viral vector, and utilization of immunomodulatory molecules. This review will focus on discussing strategies that circumvent immune tolerance and provide updates on findings from recent clinical trials.

Identification of immunogenic MAGED4B peptides for vaccine development in oral cancer immunotherapy

The ever-increasing number of tumor-associated antigens has provided a major stimulus for the development of therapeutic peptides vaccines. Tumor-associated peptides can induce high immune response rates and have been developed as vaccines for several types of solid tumors, and many are at various stages of clinical testing. MAGED4B, a melanoma antigen, is overexpressed in oral squamous cell carcinoma (OSCC) and this expression promotes proliferation and cell migration. In this study, we have identified 9 short peptides derived from MAGED4B protein that are restricted in binding to the HLA subtypes common in the Asian population (HLA-A2, A11, and A24). The peptides had good binding affinity with the MHC-Class I molecules and stimulated ex-vivo IFN-gamma and Granzyme-B production in blood samples from OSCC patients, suggesting that they are immunogenic. Further, T cells stimulated with peptide-pulsed dendritic cells showed enhanced T-cell cytotoxic activity against MAGED4B-overexpressing OSCC cell lines. In summary, we have identified MAGED4B peptides that induce anti-tumor immune responses advocating that they could be further developed as vaccine candidates for the treatment of OSCC.

Tecemotide: an antigen-specific cancer immunotherapy

The identification of tumor-associated antigens (TAA) has made possible the development of antigen-specific cancer immunotherapies such as tecemotide. One of those is mucin 1 (MUC1), a cell membrane glycoprotein expressed on some epithelial tissues such as breast and lung. In cancer, MUC1 becomes overexpressed and aberrantly glycosylated, exposing the immunogenic tandem repeat units in the extracellular domain of MUC1. Designed to target tumor associated MUC1, tecemotide is being evaluated in Phase III clinical trials for treatment of unresectable stage IIIA/IIIB non-small cell lung cancer (NSCLC) as maintenance therapy following chemoradiotherapy. Additional Phase II studies in other indications are ongoing. This review discusses the preclinical and clinical development of tecemotide, ongoing preclinical studies of tecemotide in human MUC1 transgenic mouse models of breast and lung cancer, and the potential application of these models for optimizing the timing of chemoradiotherapy and tecemotide immunotherapy to achieve the best treatment outcome for patients.

Antigen-specific vaccines for cancer treatment

Vaccines targeting pathogens are generally effective and protective because based on foreign non-self antigens which are extremely potent in eliciting an immune response. On the contrary, efficacy of therapeutic cancer vaccines is still disappointing. One of the major reasons for such poor outcome, among others, is the difficulty of identifying tumor-specific target antigens which should be unique to the tumors or, at least, overexpressed on the tumors as compared to normal cells. Indeed, this is the only option to overcome the peripheral immune tolerance and elicit a non toxic immune response. New and more potent strategies are now available to identify specific tumor-associated antigens for development of cancer vaccine approaches aiming at eliciting targeted anti-tumor cellular responses. In the last years this aspect has been addressed and many therapeutic vaccination strategies based on either whole tumor cells or specific antigens have been and are being currently evaluated in clinical trials. This review summarizes the current state of cancer vaccines, mainly focusing on antigen-specific approaches.

To affinity and beyond: harnessing the T cell receptor for cancer immunotherapy

T cell adoptive therapies for immune-mediated regression of cancers have attracted a great deal of recent attention. Clinical results are glamorous, yet much remains to be uncovered behind the basic science that allows us to engineer T cells and T cell receptors (TCRs) for clinical use. We discuss the development of TCRs for therapeutic use in the context of thymic selection toward central tolerance and we review therapies based on tumor infiltrating lymphocytes (TILs), endogenous antigen specific TCRs, and engineered TCRs. Further we discuss the development of low and high affinity TCRs and the extent to which each challenges central tolerance. Current results suggest that adaptation of TCR engineering of moderate affinity TCRs coupled with co-regulatory and stimulatory molecules may be the safest and most efficacious road for TCR development aimed at tumor abolition.

Dendritic cell defects in the colorectal cancer

Colorectal cancer (CRC) results from the accumulation of both genetic and epigenetic alterations of the genome. However, also the formation of an inflammatory milieu plays a pivotal role in tumor development and progression. Dendritic cells (DCs) play a relevant role in tumor by exerting differential pro-tumorigenic and anti-tumorigenic functions, depending on the local milieu. Quantitative and functional impairments of DCs have been widely observed in several types of cancer, including CRC, representing a tumor-escape mechanism employed by cancer cells to elude host immunosurveillance.

Understanding the interactions between DCs and tumors is important for comprehending the mechanisms of tumor immune surveillance and escape, and provides novel approaches to therapy of cancer. This review summarizes updated information on the role of the DCs in colon cancer development and/or progression.

Dengue virus specific dual HLA binding T cell epitopes induce CD8+ T cell responses in seropositive individuals

Dengue virus infects an estimated 300 million people each year and even more are at risk of becoming infected as the virus continues to spread into new areas. Despite the increase in viral prevalence, no anti-viral medications or vaccines are approved for treating or preventing infection. CD8+ T cell responses play a major role in viral clearance. Therefore, effective vaccines that induce a broad, multi-functional T cell response with substantial cross-reactivity between all virus serotypes can have major impacts on reducing infection rates and infection related complications. Here, we took an immunoproteomic approach to identify novel MHC class I restricted T cell epitopes presented by dengue virus infected cells, representing the natural and authentic targets of the T cell response. Using this approach we identified 4 novel MHC-I restricted epitopes: 2 with the binding motif for HLA-A24 molecules and 2 with both HLA-A2 and HLA-A24 binding motifs. These peptides were able to activate CD8+ T cell responses in both healthy, seronegative individuals and in seropositive individuals who have previously been infected with dengue virus. Importantly, the dual binding epitopes activated pre-existing T cell precursors in PBMCs obtained from both HLA-A2+ and HLA-A24+ seropositive individuals. Together, the data indicate that these epitopes are immunologically relevant T cell activating peptides presented on infected cells during a natural infection and therefore may serve as candidate antigens for the development of effective multi-serotype specific dengue virus vaccines.

The host immune dynamics of pneumococcal colonization: implications for novel vaccine development

The human nasopharynx (NP) microbiota is complex and diverse and Streptococcus pneumoniae (pneumococcus) is a frequent member. In the first few years of life, children experience maturation of their immune system thereby conferring homeostatic balance in which pneumococci are typically rendered as harmless colonizers in the upper respiratory environment. Pneumococcal carriage declines in many children before they acquire capsular-specific antibodies, suggesting a capsule antibody-independent mechanism of natural protection against pneumococcal carriage in early childhood. A child's immune system in the first few years of life is Th2-skewed so as to avoid inflammation-induced immunopathology. Understanding Th1/Th2 and Th17 ontogeny in early life and how adjuvant vaccine formulations shift the balance of T helper-cell differentiation, may facilitate the development of new protein-based pneumococcal vaccines. This article will discuss the immune dynamics of pneumococcal colonization in infants. The discussion aims to benefit the design and improvement of protein subunit-based next-generation pneumococcal vaccines.

Generation of potent mouse monoclonal antibodies to self-proteins using T-cell epitope "tags"

Immunization of mice or rats with a "non-self" protein is a commonly used method to obtain monoclonal antibodies, and relies on the immune system's ability to recognize the immunogen as foreign. Immunization of an antigen with 100% identity to the endogenous protein, however, will not elicit a robust immune response. To develop antibodies to mouse proteins, we focused on the potential for breaking such immune tolerance by genetically fusing two independent T-cell epitope-containing sequences (from tetanus toxin (TT) and diphtheria toxin fragment A (DTA)) to a mouse protein, mouse ST2 (mST2). Wild-type CD1 mice were immunized with three mST2 tagged proteins (Fc, TT and DTA) and the specific serum response was determined. Only in mice immunized with the T-cell epitope-containing antigens were specific mST2 serum responses detected; hybridomas generated from these mice secreted highly sequence-diverse IgGs that were capable of binding mST2 and inhibiting the interaction of mST2 with its ligand, mouse interleukin (IL)-33 (mIL-33). Of the hundreds of antibodies profiled, we identified five potent antibodies that were able to inhibit IL-33 induced IL-6 release in a mast cell assay; notably one such antibody was sufficiently potent to suppress IL-5 release and eosinophilia infiltration in an Alternaria alternata challenge mouse model of asthma. This study demonstrated, for the first time, that T-cell epitope-containing tags have the ability to break tolerance in wild-type mice to 100% conserved proteins, and it provides a compelling argument for the broader use of this approach to generate antibodies against any mouse protein or conserved ortholog.

β2-Microglobulin is an appropriate reference gene for RT-PCR-based gene expression analysis of hematopoietic stem cells

Real-time reverse transcription polymerase chain reaction (RT-PCR) is regarded as one of the most useful and powerful tools for characterizing hematopoietic stem cells (HSCs), because samples of extremely small cell numbers can be analyzed. The expression levels determined by RT-PCR are based on relative quantification; therefore, the selection of an appropriate reference gene with a relatively stable expression level under most conditions is crucial. Here, we determined that beta2-microglobulin (B2m) is an appropriate reference gene for analyzing mouse HSCs by a novel method using single-cell RT-PCR. Clonally sorted HSCs were subjected to RT reactions with exogenous RNA fragments and then to real-time PCR. Next, the relative gene expression levels of 4 well-known housekeeping genes were quantified in each single cell sample based on the threshold cycle of exogenous RNA. The analysis revealed that B2m expression was reproducibly detected in almost all HSCs and that B2m had the most stable expression level among the compared genes, even after the cells had been cultured under various conditions. Thus, our results indicate that B2m can reliably be used as a reference gene for the relative quantification of expression levels in HSCs across various conditions. Furthermore, our work proposes a novel method for the selection of appropriate reference genes.

Using RNA sequencing for identifying gene imprinting and random monoallelic expression in human placenta

Given the possible critical importance of placental gene imprinting and random monoallelic expression on fetal and infant health, most of those genes must be identified, in order to understand the risks that the baby might meet during pregnancy and after birth. Therefore, the aim of the current study was to introduce a workflow and tools for analyzing imprinted and random monoallelic gene expression in human placenta, by applying whole-transcriptome (WT) RNA sequencing of placental tissue and genotyping of coding DNA variants in family trios. Ten family trios, each with a healthy spontaneous single-term pregnancy, were recruited. Total RNA was extracted for WT analysis, providing the full sequence information for the placental transcriptome. Parental and child blood DNA genotypes were analyzed by exome SNP genotyping microarrays, mapping the inheritance and estimating the abundance of parental expressed alleles. Imprinted genes showed consistent expression from either parental allele, as demonstrated by the SNP content of sequenced transcripts, while monoallelically expressed genes had random activity of parental alleles. We revealed 4 novel possible imprinted genes (LGALS8, LGALS14, PAPPA2 and SPTLC3) and confirmed the imprinting of 4 genes (AIM1, PEG10, RHOBTB3 and ZFAT-AS1) in human placenta. The major finding was the identification of 4 genes (ABP1, BCLAF1, IFI30 and ZFAT) with random allelic bias, expressing one of the parental alleles preferentially. The main functions of the imprinted and monoallelically expressed genes included: i) mediating cellular apoptosis and tissue development; ii) regulating inflammation and immune system; iii) facilitating metabolic processes; and iv) regulating cell cycle.

HLA-DRB1 and HLA-DQB1 methylation changes promote the occurrence and progression of Kazakh ESCC

Human leukocyte antigen II (HLA-II) plays an important role in host immune responses to cancer cells. Changes in gene methylation may result in aberrant expression of HLA-II, serving a key role in the pathogenesis of Kazakh esophageal squamous cell carcinoma (ESCC). We analyzed the expression level of HLA-II (HLA-DP, -DQ, and -DR) by immunohistochemistry, as well as the methylation status of HLA-DRB1 and HLA-DQB1 by MassARRAY spectrometry in Xinjiang Kazakh ESCC. Expression of HLA-II in ESCC was significantly higher than that in cancer adjacent normal (ACN) samples (P < 0.05). Decreased HLA-II expression was closely associated with later clinical stages of ESCC (P < 0.05). Hypomethylation of HLA-DRB1 and hypermethylation of HLA-DQB1 was significantly correlated with occurrence of Kazakh ESCC (P < 0.01), and mainly manifested as hypomethylation of CpG9, CpG10-11, and CpG16 in HLA-DRB1 and hypermethylation of CpG6-7 and CpG16-17 in HLA-DQB1 (P < 0.01). Moreover, hypomethylation of HLA-DQB1 CpG6-7 correlated with poor differentiation in ESCCs, whereas hypermethylation of HLA-DRB1 CpG16 and hypomethylation of HLA-DQB1 CpG16-17 were significantly associated with later stages of ESCC (P < 0.05). A significant inverse association between HLA-DRB1 CpG9 methylation and HLA-II expression was found in ESCC (P < 0.05). These findings suggest aberrant HLA-DRB1 and HLA-DQB1 methylation contributes to the aberrant expression of HLA-II. These molecular changes may influence the immune response to specific tumor epitopes, promoting the occurrence and progression of Kazakh ESCC.

Genome-wide DNA methylation variability in adolescent monozygotic twins followed since birth

DNA methylation patterns are characterized by highly conserved developmental programs, but allow for divergent gene expression resulting from stochastic epigenetic drift or divergent environments. Genome-wide methylation studies in monozygotic (MZ) twins are providing insight into the extent of epigenetic variation that occurs, irrespective of genotype. However, little is known about the variability of DNA methylation patterns in adolescence, a period involving significant and rapid physical, emotional, social, and neurodevelopmental change. Here, we assessed genome-wide DNA methylation using the 450 K Illumina BeadChip in a sample of 37 MZ twin pairs followed longitudinally since birth to investigate: 1) the extent of variation in DNA methylation in identical genetic backgrounds in adolescence and; 2) whether these variations are randomly distributed or enriched in particular functional pathways. We also assessed stability of DNA methylation over 3-6 months to distinguish stable trait-like and variable state-like genes. A pathway analysis found high within-pair variability in genes associated with development, cellular mechanisms, tissue and cell morphology, and various disorders. Test-retest analyses performed in a sub-sample of 8 twin pairs demonstrated enrichment in gene pathways involved in organismal development, cellular growth and proliferation, cell signaling, and particular disorders. The variability found in functional gene pathways may plausibly underlie phenotypic differences in this adolescent MZ twin sample. Furthermore, we assessed stability of methylation over 3-6 months and found that some genes were stable while others were unstable, suggesting that the methylome remains dynamic in adolescence and that dynamic sites tend to be organized in certain gene pathways.

IL-10 enhances CTL-mediated tumor rejection by inhibiting highly suppressive CD4+ T cells and promoting CTL persistence in a murine model of plasmacytoma

Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine that regulates immune responses. IL-10 has also been shown to enhance antitumor CD8⁺ T-cell responses in tumor models although the underlying mechanisms are not fully understood. In this study, we used a series of genetic mouse models and the mouse plasmacytoma J558 model to investigate this issue. J558 tumors grew significantly faster in IL-10^-/- mice than in wild type (WT) mice, but similarly in IL-10 ^-/- Rag2 ^-/- and Rag2 ^-/- mice. Tumors from IL-10 ^-/- mice contained fewer IFN-γ-producing CD8⁺ and CD4⁺ T cells than tumors from WT mice. Strikingly, depletion of total CD4⁺ T cells, but not CD25⁺ cells, resulted in tumor eradication in IL-10 ^-/- mice. Adoptive transfer studies revealed that CD4⁺ T cells from IL-10 ^-/- mice exhibited more potent suppression of cytotoxic T lymphocyte (CTL)-mediated tumor rejection than their WT counterparts, and IL-10-deficient tumor-infiltrating CD4⁺ T cells expressed higher levels of PD-L1 and CTLA-4 inhibitory molecules. Although IL-10-deficient CD8⁺ T cells are not defective in activation and initial rejection of tumors, adoptive transfer studies using IL-10-deficient P1CTL transgenic T cells that recognize the tumor rejection antigen P1A reveal that IL-10 is required for long-term persistence of CTLs and control of tumor growth. Thus, we have found that IL-10 enhances antitumor CTL responses by inhibiting highly suppressive CD4⁺ T cells and promoting CTL persistence. These data have important implications for the design of immunotherapy for human cancer.

Vγ9Vδ2-T cells as antigen presenting cells for iNKT cell based cancer immunotherapy

CD1d-restricted invariant natural killer T cells (iNKT) constitute an important immunoregulatory T-cell subset involved in the induction of antitumor immune responses. Here, we provide a view on the recent observation that Vγ9Vδ2-T cells, through trogocytosis of CD1d-containing membrane fragments, have the capacity to act as antigen presenting cells for iNKT.

Are BiTEs the "missing link" in cancer therapy?

Conventional treatment for cancer routinely includes surgical resection and some combination of chemotherapy and radiation. These approaches are frequently accompanied by unintended and highly toxic collateral damage to healthy tissues, which are offset by only marginal prognostic improvements in patients with advanced cancers. This unfortunate balance has driven the development of novel therapies that aim to target tumors both safely and efficiently. Over the past decade, mounting evidence has supported the therapeutic utility of T-cell-centered cancer immunotherapy, which, in its various iterations, has been shown capable of eliciting highly precise and robust antitumor responses both in animal models and human trials. The identification of tumor-specific targets has further fueled a growing interest in T-cell therapies given their potential to circumvent the non-specific nature of traditional treatments. Of the several strategies geared toward achieving T-cell recognition of tumor, bispecific antibodies (bsAbs) represent a novel class of biologics that have garnered enthusiasm in recent years due to their versatility, specificity, safety, cost, and ease of production. Bispecific T-cell Engagers (BiTEs) are a subclass of bsAbs that are specific for CD3 on one arm and a tumor antigen on the second. As such, BiTEs function by recruiting and activating polyclonal populations of T-cells at tumor sites, and do so without the need for co-stimulation or conventional MHC recognition. Blinatumomab, a well-characterized BiTE, has emerged as a promising recombinant bscCD19×CD3 construct that has demonstrated remarkable antitumor activity in patients with B-cell malignancies. This clinical success has resulted in the rapid extension of BiTE technology against a greater repertoire of tumor antigens and the recent US Food and Drug Administration's (FDA) accelerated approval of blinatumomab for the treatment of a rare form of acute lymphoblastic leukemia (ALL). In this review, we dissect the role of T-cell therapeutics in the new era of cancer immunotherapy, appraise the value of CAR T-cells in the context of solid tumors, and discuss why the BiTE platform may rescue several of the apparent deficits and shortcomings of competing immunotherapies to support its widespread clinical application.