Advancements in immune tolerance

LILRB4 Checkpoint for Immunotherapy: Structure, Mechanism and Disease Targets

LILRB4, a myeloid inhibitory receptor belonging to the family of leukocyte immunoglobulin-like receptors (LILRs/LIRs), plays a pivotal role in the regulation of immune tolerance. LILRB4 primarily mediates suppressive immune responses by transmitting inhibitory signals through immunoreceptor tyrosine-based inhibitory motifs (ITIMs). This immune checkpoint molecule has gained considerable attention due to its potent regulatory functions. Its ability to induce effector T cell dysfunction and promote T suppressor cell differentiation has been demonstrated, indicating the therapeutic potential of LILRB4 for modulating excessive immune responses, particularly in autoimmune diseases or the induction of transplant tolerance. Additionally, through intervening with LILRB4 molecules, immune system responsiveness can be adjusted, representing significant value in areas such as cancer treatment. Thus, LILRB4 has emerged as a key player in addressing autoimmune diseases, transplant tolerance induction, and other medical issues. In this review, we provide a comprehensive overview of LILRB4, encompassing its structure, expression, and ligand molecules as well as its role as a tolerance receptor. By exploring the involvement of LILRB4 in various diseases, its significance in disease progression is emphasized. Furthermore, we propose that the manipulation of LILRB4 represents a promising immunotherapeutic strategy and highlight its potential in disease prevention, treatment and diagnosis.

Fourier-transform infrared spectroscopy: a universal optical sensing technique with auspicious application prospects in the diagnosis and management of autoimmune diseases

Autoimmune diseases (AIDs) are poorly understood clinical syndromes due to breakdown of immune tolerance towards specific types of self-antigens. They are generally associated with an inflammatory response mediated by lymphocytes T, autoantibodies or both. Ultimately, chronic inflammation culminates in tissue damages and clinical manifestations. AIDs affect 5% of the world population, and they represent the main cause of fatality in young to middle-aged females. In addition, the chronic nature of AIDs has a devastating impact on the patient's quality of life. It also places a heavy burden on the health care system. Establishing a rapid and accurate diagnosis is considered vital for an ideal medical management of these autoimmune disorders. However, for some AIDs, this task might be challenging. Vibrational spectroscopies, and more particularly Fourier-transform infrared (FTIR) spectroscopy, have emerged as universal analytical techniques with promising applications in the diagnosis of various types of malignancies and metabolic and infectious diseases. The high sensitivity of these optical sensing techniques and their minimal requirements for test reagents qualify them to be ideal analytical techniques. The aim of the current review is to explore the potential applications of FTIR spectroscopy in the diagnosis and management of most common AIDs. It also aims to demonstrate how this technique has contributed to deciphering the biochemical and physiopathological aspects of these chronic inflammatory diseases. The advantages that can be offered by this optical sensing technique over the traditional and gold standard methods used in the diagnosis of these autoimmune disorders have also been extensively discussed.

Recent Advances in Hyperthermia Therapy-Based Synergistic Immunotherapy

The past decades have witnessed hyperthermia therapy (HTT) as an emerging strategy against malignant tumors. Nanomaterial-based photothermal therapy (PTT) and magnetic hyperthermia (MHT), as highly effective and noninvasive treatment models, offer advantages over other strategies in the treatment of different types of tumors. However, both PTT and MHT cannot completely cure cancer due to recurrence and distal metastasis. In recent years, cancer immunotherapy has attracted widespread attention owing to its capability to activate the body's own natural defense to identify, attack, and eradicate cancer cells. Significant efforts have been devoted to studying the activated immune responses caused by hyperthermia-ablated tumors. In this article, the synergistic mechanism of HTT in immunotherapy, including immunogenic cell death and reversal of the immunosuppressive tumor microenvironment is discussed. The reports of the combination of HTT or HTT-based multimodal therapy with immunotherapy, including immunoadjuvant exploitation, immune checkpoint blockade therapy, and adoptive cellular immunotherapy are summarized. As highlighted, these strategies could achieve synergistically enhanced therapeutic outcomes against both primary tumors and metastatic lesions, prevent cancer recurrence, and prolong the survival period. Finally, current challenges and prospective developments in HTT-synergized immunotherapy are also reviewed.

Immune system and cholangiocytes: A puzzling affair in primary biliary cholangitis

Primary biliary cholangitis (PBC) is a cholestatic liver disease characterized by the destruction of the small and medium bile ducts. Its pathogenesis is still unknown. Despite the genome wide association study findings, the therapies targeting the cytokines pathway, tested so far, have failed. The concept of the biliary epithelium as a key player of the PBC pathogenesis has emerged over the last few years. It is now well accepted that the biliary epithelial cells (BECs) actively participate to the genesis of the damage. The chronic stimulation of BECs via microbes and bile changes the cell phenotype toward an active state, which, across the production of proinflammatory mediators, can recruit, retain, and activate immune cells. The consequent immune system activation can in turn damage BECs. Thus, the crosstalk between both innate and adaptive immune cells and the biliary epithelium creates a paracrine loop responsible for the disease progression. In this review, we summarize the evidence provided in literature about the role of BECs and the immune system in the pathogenesis of PBC. We also dissect the relationship between the immune system and the BECs, focusing on the unanswered questions and the future potential directions of the translational research and the cellular therapy in this area.

The mechanistic study behind suppression of GVHD while retaining GVL activities by myeloid-derived suppressor cells

Graft-versus-host disease (GVHD) is a major barrier to the widespread use of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for treating hematologic malignancies. Myeloid-derived suppressor cells (MDSCs) have been recognized as crucial immunosuppressive cells in various pathologic settings. Here, we investigated whether the unique functional properties of MDSCs could be harnessed to control allo-HSCT-associated GVHD. Using multiple murine GVHD/GVL models including both MHC-mismatched and miHA-mismatched, we demonstrated that treatment with CD115+ MDSCs efficiently suppressed GVHD but did not significantly impair graft-versus-leukemia (GVL) activity, leading to 80% and 67% protection in treated mice in GVHD and GVL models, respectively. The mechanism for this dissociation of GVHD from GVL, specifically the emergence of donor-derived NKG2D⁺ CD8 T cells with a memory phenotype in MDSC-treated recipient mice, was identified. NKG2D expression on donor T cells was required for eradication of allogeneic lymphoma cells. Furthermore, long-term surviving MDSC recipients that exhibited cytolytic activities against allogeneic leukemia cells had a significantly increased percentage of T regulatory cells and, more importantly, NKG2D⁺ CD8 T cells. These findings indicate that MDSCs can be used as a novel cell-based therapy to suppress GVHD while maintaining GVL activities through selective induction of NKG2D⁺ CD8 memory T cells.

HisgAtlas 1.0: a human immunosuppression gene database

Immunosuppression is body's state in which the activation or efficacy of immune system is weakened. It is associated with a wide spectrum of human diseases. In the last two decades, tremendous efforts have been made to elucidate the mechanism of hundreds of immunosuppression genes. Immunosuppression genes could be valuable drug targets or biomarkers for the immunotherapeutic treatment of different diseases. However, the information of all previously identified immunosuppression genes is dispersed in thousands of publications. Here, we provide the HisgAtlas database that collects 995 previously identified human immunosuppression genes using text mining and manual curation. We believe HisgAtlas will be a valuable resource to search human immunosuppression genes as well as to investigate their functions in further research. Database URL: http://biokb.ncpsb.org/HisgAtlas/.

Transient and Local Expression of Chemokine and Immune Checkpoint Traps To Treat Pancreatic Cancer

Pancreatic tumors are known to be resistant to immunotherapy due to the extensive immune suppressive tumor microenvironment (TME). We hypothesized that CXCL12 and PD-L1 are two key molecules controlling the immunosuppressive TME. Fusion proteins, called traps, designed to bind with these two molecules with high affinity (K_d = 4.1 and 0.22 nM, respectively) were manufactured and tested for specific binding with the targets. Plasmid DNA encoding for each trap was formulated in nanoparticles and intravenously injected to mice bearing orthotopic pancreatic cancer. Expression of traps was mainly seen in the tumor, and secondarily, accumulations were primarily in the liver. Combination trap therapy shrunk the tumor and significantly prolonged the host survival. Either trap alone only brought in a partial therapeutic effect. We also found that CXCL12 trap allowed T-cell penetration into the tumor, and PD-L1 trap allowed the infiltrated T-cells to kill the tumor cells. Combo trap therapy also significantly reduced metastasis of the tumor cells to other organs. We conclude that the trap therapy significantly modified the immunosuppressive TME to allow the host immune system to kill the tumor cells. This can be an effective therapy in clinical settings.

Tumor microenvironment and noncoding RNAs as co-drivers of epithelial-mesenchymal transition and cancer metastasis

Reciprocal interactions between cancer cells and tumor microenvironment (TME) are crucial events in tumor progression and metastasis. Pervasive stromal reprogramming of TME modifies numerous cellular functions, including extracellular matrix (ECM) stiffness, inflammation, and immunity. These environmental factors allow selection of more aggressive cells that develop adaptive strategies associating plasticity and epithelial-mesenchymal transition (EMT), stem-like phenotype, invasion, immunosuppression, and resistance to therapies. EMT is a morphomolecular process that endows epithelial tumor cells with mesenchymal properties, including reduced adhesion and increased motility. Numerous studies have demonstrated involvement of noncoding RNAs (ncRNAs), such as miRNAs and lncRNAs, in tumor initiation, progression, and metastasis. NcRNAs regulate every hallmark of cancer and have now emerged as new players in induction and regulation of EMT. The reciprocal regulatory interactions between ncRNAs, TME components, and cancer cells increase the complexity of gene expression and protein translation in cancer. Thus, deeper understanding of molecular mechanisms controlling EMT will not only shed light on metastatic processes of cancer cells, but enhance development of new therapies targeting metastasis. In this review, we will provide recent findings on the role of known ncRNAs relevant to EMT and cancer metastasis and discuss the role of the interaction between ncRNAs and TME as co-drivers of EMT. Developmental Dynamics 247:405-431, 2018. © 2017 Wiley Periodicals, Inc.

Taming the immune system through transfusion in oncology patients

Blood transfusion is a clinical replacement therapy with many successes with some benefit and, also, some harm. Cancer is a multifaceted disease potentially associated with the immune system's weakness where the cancerous tumor cells escape from the immune system. Allogeneic blood transfusion, through five major mechanisms including the lymphocyte-T set, myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), natural killer cells (NKCs), and dendritic cells (DCs) can help the recipient's defense mechanisms. On the other hand, the role for each of the listed items includes activation of the antitumor CD8+ cytotoxic T lymphocytes (CD8+/CTL), temporal inactivation of Tregs, inactivation of the STAT3 signaling pathway, the use of bacteria to enhance the antitumor immune response and cellular immunotherapy. The above issues are concisely addressed in this manuscript based on a literature survey on this topic carried out by the first author.

Curcumin Micelles Remodel Tumor Microenvironment and Enhance Vaccine Activity in an Advanced Melanoma Model

Previously, we have reported a lipid-based Trp2 peptide vaccine for immunotherapy against melanoma. The suppressive immune microenvironment in the tumor is a major hurdle for an effective vaccine therapy. We hypothesized that curcumin (CUR) would remodel the tumor microenvironment to improve the vaccine activity. Curcumin-polyethylene glycol conjugate (CUR-PEG), an amphiphilic CUR-based micelle, was delivered intravenously (i.v.) to the tumor. Indeed, in the B16F10 tumor-bearing mice, the combination of CUR-PEG and vaccine treatment resulted in a synergistic antitumor effect (P < 0.001) compared to individual treatments. In the immune organs, the combination therapy significantly boosted in vivo cytotoxic T-lymphocyte response (41.0 ± 5.0% specific killing) and interferon-γ (IFN-γ) production (sevenfold increase). In the tumor microenvironment, the combination therapy led to significantly downregulated levels of immunosuppressive factors, such as decreased numbers of myeloid-derived suppressor cells and regulatory T cells (Treg) cells and declined levels of interleukin-6 and chemokine ligand 2-in correlation with increased levels of proinflammatory cytokines, including tumor necrosis factor-α and IFN-γ as well as an elevation in the CD8(+) T-cell population. The results indicated a distinct M2 to M1 phenotype switch in the treated tumors. Combining CUR-PEG and vaccine also dramatically downregulated the signal transducer and activator of transcription 3 pathway (76% reduction). Thus, we conclude that CUR-PEG is an effective agent to improve immunotherapy for advanced melanoma.

Tolerogenic Dendritic Cells on Transplantation: Immunotherapy Based on Second Signal Blockage

Dendritic cells (DCs), the most important professional antigen-presenting cells (APC), play crucial role in both immunity and tolerance. It is well known that DCs are able to mount immune responses against foreign antigens and simultaneously tolerate self-antigens. Since DCs can be modulated depending on the surrounding microenvironment, they can act as a bridge between innate and adaptive immunity. However, the mechanisms that support this dual role are not entirely clear. Recent studies have shown that DCs can be manipulated ex vivo in order to trigger their tolerogenic profile, what can be a tool to be used in clinical trials aiming the treatment of various diseases and the prevention of transplant rejection. In this sense, the blockage of costimulatory molecules on DC, in the attempt of inhibiting the second signal in the immunological synapse, can be considered as one of the main strategies under development. This review brings an update on current therapies using tolerogenic dendritic cells modulated with costimulatory blockers with the aim of reducing transplant rejection. However, although there are current clinical trials using tolerogenic DC to treat allograft rejection, the actual challenge is to modulate these cells in order to maintain a permanent tolerogenic profile.

Pivotal role of pervasive neoplastic and stromal cells reprogramming in circulating tumor cells dissemination and metastatic colonization

Reciprocal interactions between neoplastic cells and their microenvironment are crucial events in carcinogenesis and tumor progression. Pervasive stromal reprogramming and remodeling that transform a normal to a tumorigenic microenvironment modify numerous stromal cells functions, status redox, oxidative stress, pH, ECM stiffness and energy metabolism. These environmental factors allow selection of more aggressive cancer cells that develop important adaptive strategies. Subpopulations of cancer cells acquire new properties associating plasticity, stem-like phenotype, unfolded protein response, metabolic reprogramming and autophagy, production of exosomes, survival to anoikis, invasion, immunosuppression and therapeutic resistance. Moreover, by inducing vascular transdifferentiation of cancer cells and recruiting endothelial cells and pericytes, the tumorigenic microenvironment induces development of tumor-associated vessels that allow invasive cells to gain access to the tumor vessels and to intravasate. Circulating cancer cells can survive in the blood stream by interacting with the intravascular microenvironment, extravasate through the microvasculature and interact with the metastatic microenvironment of target organs. In this review, we will focus on many recent paradigms involved in the field of tumor progression.

Blocking HIF-1α following radiotherapy to prolong and enhance the immune effects of radiotherapy: a hypothesis

Tumor local immune escape is one of the “hallmarks” of cancer leading to poor prognosis. The effects of local radiotherapy on tumors are rapidly emerging as opportunities to remodel and enhance immunity against cancer. However, this immunity remodeling and enhancing are not permanent after local radiotherapy. High expression of HIF-1α following local radiotherapy for tumor cell reoxygenation has been confirmed, and recently accumulating evidence shows the tumor immune suppression effects. These research findings suggest a new direction in the investigation of methods to enhance the efficacy of local radiotherapy. We speculate that by blocking HIF-1α, the immune effects of radiotherapy might be prolonged and enhanced.

Developing Phytocompounds from Medicinal Plants as Immunomodulators

Imbalance or malfunction of the immune systems is associated with a range of chronic diseases including autoimmune diseases, allergies, cancers and others. Various innate and adaptive immune cells that are integrated in this complex networking system may represent promising targets for developing immunotherapeutics for treating specific immune diseases. A spectrum of phytochemicals have been isolated, characterized and modified for development and use as prevention or treatment of human diseases. Many cytotoxic drugs and antibiotics have been developed from phytocompounds, but the application of traditional or new medicinal plants for use as immunomodulators in treating immune diseases is still relatively limited. In this review, a selected group of medicinal herbs, their derived crude or fractionated phytoextracts and the specific phytochemicals/phytocompounds isolated from them, as well as categorized phytocompound groups with specific chemical structures are discussed in terms of their immunomodulatory bioactivities. We also assess their potential for future development as immunomodulatory or inflammation-regulatory therapeutics or agents. New experimental approaches for evaluating the immunomodulatory activities of candidate phytomedicines are also discussed.

The potential role of preventing atherosclerosis by induction of neonatal tolerance to VLDL

Induction of immune tolerance to ox-LDL could reduce atherosclerosis by modulation immune response. We suppose that very low density lipoprotein (VLDL) may have a similar role to ox-LDL in autoimmune response of atherosclerosis. In this study, neonatal rats were injected with ox-LDL, VLDL, or equal-volume saline, respectively. Vaccination with ox-LDL reduced the level of specific antibody, T cells proliferation response, and the level of endothelins. The method also had a tendency of reducing blood lipids. Vaccination with VLDL obviously reduced the level of specific antibody and T cells proliferation. Though there was also a tendency of reducing blood lipids and endothelins, the effect was less prominent than that with ox-LDL. We conclude that, although the effect was less obvious, vaccination with VLDL to induce neonatal tolerance had an effect on modulating immune response, protecting endothelial cells, and reducing blood lipids.

Prolonged infection by Fonsecaea pedrosoi after antigenic co-stimulation at different sites in experimental murine chromoblastomycosis

In the present study, we examined prolonged infection after antigenic co-stimulation by inoculation of the fungus Fonsecaea pedrosoi at two different sites in three mouse strains (BALB/c, Swiss, and C57BL/6). Using this murine model of infection, we showed that antigen induction of infection at more than one site led to a local suppression of active lesions, which increased the time course of experimental chromoblastomycosis (CBM). Footpad infection with a simultaneous infection of the peritoneum or a mucosal site appeared to cause prolonged infection and frequent fungal disseminations. Using knockout (KO) mice, we observed that antigenic co-stimulation caused progressive illness in CD8-KO animals and an effective immune response in the absence of IL-10. In Xid mice, co-stimulation provoked chronic infection (not prolonged), suggesting that B1 B cells play an important role in the control of fungal infection. The tissue response to infection was similar in all co-stimulated mouse groups, as anatomopathologic sections revealed multifocal lesions (granuloma-like). In general, these mice had acute responses at primary antigenic sites with an intense migration of polymorphonuclear leukocytes (PMNs), whereas the distant infection sites (footpad) showed signs of chronic infection. The migration of PMNs to the secondary site (footpad) increased in the later periods of infection, especially after the disappearance of the primary antigenic focus. PMN migration was associated with lesion-dormancy breakage and fungal elimination. Our findings suggest that the host inflammatory/suppression mechanisms induced by antigenic co-stimulation to systemically fight the same pathogen act coordinately through responses that differ at the sites of infection between acute and chronic integrated healing processes that are more prolonged than an acute infection at a single site. However, the long persistence of fungal cells in the host may be linked to microbial adaptation to a parasitic infection as observed in co-stimulated Xid mice.

Contribution of myeloid-derived suppressor cells to tumor-induced immune suppression, angiogenesis, invasion and metastasis

Growing evidence suggests that myeloid-derived suppressor cells (MDSCs), which have been named "immature myeloid cells" or "myeloid suppressor cells" (MSCs), play a critical role during the progression of cancer in tumor-bearing mice and cancer patients. As their name implies, these cells are derived from bone marrow and have a tremendous potential to suppress immune responses. Recent studies indicated that these cells also have a crucial role in tumor progression. MDSCs can directly incorporate into tumor endothelium. They secret many pro-angiogenic factors as well. In addition, they play an essential role in cancer invasion and metastasis through inducing the production of matrix metalloproteinases (MMPs), chemoattractants and creating a pre-metastatic environment. Increasing evidence supports the idea that cancer stem cells (CSCs) are responsible for tumorigenesis, resistance to therapies, invasion and metastasis. Here, we hypothesize that CSCs may "hijack" MDSCs for use as alternative niche cells, leading to the maintenance of stemness and enhanced chemo- and radio-therapy resistance. The countermeasure that directly targets to MDSCs may be useful for against angiogenesis and preventing cancer from invasion and metastasis. Therefore, the study of MDSCs is important to understand tumor progression and to enhance the therapeutic efficacy against cancer.

Stromal cell-induced immune regulation in a transplantable lymphoid-like cell constructs

Engineering of cell-based constructs for treating a variety of immune-related diseases by local transplantation of the cells in a pre-designed matrix is an emerging therapeutic approach, which can potentially reduce the side effects associated with systemic cell injection. Stromal cells have been shown to exert immunosuppressive properties and thus can be exploited for autoimmune regulation and cell transplantation. Here, we demonstrate the fabrication of a stromal cell-based construct, which serves as a lymphoid-like organ with immune regulatory characteristics. In the proposed system, stromal cells are co-seeded with dendritic cells (DC) in a macro-porous alginate scaffold containing the encephalitogenic myelin-derived peptide, proteolipid protein (PLP). We demonstrate that the presence of stromal cells attenuates DC maturation upon lipopolysaccharide stimulus. In vitro, we show that while the migration of pathogenic PLP-specific T cells to construct cultivated with or without stromal cells does not differ, their activation and proliferation are significantly suppressed in the presence of stromal cells. Upon in vivo transplantation, under the kidney capsule of mice, the pathogenic activation and proliferation of T cells which were drawn into the construct were suppressed in the co-seeded constructs. This system thus serves as a lymphoid-like organ with regulatory characteristics, which can be applied for local tolerance induction, for application in cell transplantations as well as autoimmune diseases.

Control of allograft rejection in mice by applying a novel neuropeptide, cortistatin

INTRODUCTION

The action of cortistatin (CST), a novel cyclic neuropeptide, as an anti-inflammatory factor has been studied, but few investigations have explored the immunomodulatory role of CST in transplantation. In the present study, we examined whether CST affects the alloimmune response in a mouse model of skin transplantation and the effects of CST on T lymphocytes.

METHODS

BALB/c (H-2K(d)) recipient mice (n=70) were divided into seven groups (n=10 per group) and given an intraperitoneal injection of CST or a somatostatin analog, SMS 201-995 (octreotide), on the day of skin transplantation from C57BL/6 (B6) (H-2K(b)) donors. Injections were continued for 7 consecutive days. Groups 1-3 received CST at doses of 0.02, 0.2, or 2 mg/kg, respectively. Groups 4-6 received SMS 201-995 at the same doses. Group 7 was a control group and received injections of phosphate buffered saline. Survival of the allografts was recorded. A semiquantitative reverse transcriptase polymerase chain reaction study of Foxp3 expression and a flow cytometry study of CD4 and CD25 markers of T lymphocytes were conducted to determine whether CD4(+)CD25(+) Foxp3(high) regulatory T cells (T(reg)) were generated in vivo.

RESULTS

BALB/c mice given CST (0.2 or 2 mg/kg) had prolonged graft survival (median survival time [MST], 13 and 14 days, respectively; P<0.05 compared with controls). SMS 201-995 at the same concentrations did not have a significant effect on allograft survival (MST, 8 days for both groups). We found more than a twofold increase of CD4(+)CD25(+) T(reg) cells in the CD4(+) T-cell population and the expression of Foxp3 was up-regulated in the CST treatment groups, compared with control and SMS 201-995 treatment groups.

CONCLUSION

In our study, CST induced a significant prolongation in survival time of allogeneic skin grafts and increased the generation of CD4(+)CD25(+) Foxp 3(high) T(reg) cells. These results suggest that CST may become a new modality in controlling allograft rejection.