Induction of NKG2D ligands by gamma radiation and tumor necrosis factor-alpha may participate in the tissue damage during acute graft-versus-host disease. Transplantation. 2008;85:911-915. [PMID: 18360276 DOI: 10.1097/tp.0b013e31816691ef]

Age-associated changes in innate and adaptive immunity: role of the gut microbiota

Aging is generally regarded as an irreversible process, and its intricate relationship with the immune system has garnered significant attention due to its profound implications for the health and well-being of the aging population. As people age, a multitude of alterations occur within the immune system, affecting both innate and adaptive immunity. In the realm of innate immunity, aging brings about changes in the number and function of various immune cells, including neutrophils, monocytes, and macrophages. Additionally, certain immune pathways, like the cGAS-STING, become activated. These alterations can potentially result in telomere damage, the disruption of cytokine signaling, and impaired recognition of pathogens. The adaptive immune system, too, undergoes a myriad of changes as age advances. These include shifts in the number, frequency, subtype, and function of T cells and B cells. Furthermore, the human gut microbiota undergoes dynamic changes as a part of the aging process. Notably, the interplay between immune changes and gut microbiota highlights the gut's role in modulating immune responses and maintaining immune homeostasis. The gut microbiota of centenarians exhibits characteristics akin to those found in young individuals, setting it apart from the microbiota observed in typical elderly individuals. This review delves into the current understanding of how aging impacts the immune system and suggests potential strategies for reversing aging through interventions in immune factors.

The impact of MICB mismatches in unrelated haematopoietic stem cell transplantation

MICA polymorphisms have been associated with increased incidence of acute GvHD and adverse outcome in allogeneic haematopoietic stem cell transplantation (HSCT). MICB is another expressed member of MHC class I-related chain genes and its impact on HSCT outcome is yet to be fully defined. We typed a large cohort of patients and donors for MICB polymorphisms and investigated the impact of MICB matching on outcome after unrelated HSCT. 69.2% of the patients were 10/10 human leukocyte antigen (HLA) matched and 30.8% were 9/10 HLA matched. MICB typing was performed using a short amplicon-based NGS typing assay on the Illumina MiSeq platform. Differences in proteins were considered as mismatches. MICA polymorphisms were identified as possible confounder and were therefore included as parameter in the multivariate analyses. Due to the strong linkage disequilibrium with the classical HLA-genes, sub-stratification for HLA matching status was necessary, and no effect of MICB mismatches was seen in the 10/10 HLA matched group when compared to the MICB matched cases. However, in the 9/10 HLA matched group, MICB mismatched cases showed significantly worse disease free survival (DFS), GvHD and relapse free survival (GRFS) compared to the MICB matched cases (DFS: HR 1.24, p = 0.011; GRFS: HR 1.26, p = 0.002). MICA mismatches had no impact on any outcome parameter. According to our findings, effects previously attributed to MICA differences may have been confounded by MICB polymorphisms. We show that MICB differences contribute a small but relevant effect in 9/10 HLA-matched transplantations, which in turn highlights the possible usefulness of MICB typing in donor selection among similarly suitable 9/10 matched donors, especially when HLA-B mismatches have to be accepted.

CAR T cell-based immunotherapy and radiation therapy: potential, promises and risks

CAR T cell-based therapies have revolutionized the treatment of hematological malignancies such as leukemia and lymphoma within the last years. In contrast to the success in hematological cancers, the treatment of solid tumors with CAR T cells is still a major challenge in the field and attempts to overcome these hurdles have not been successful yet. Radiation therapy is used for management of various malignancies for decades and its therapeutic role ranges from local therapy to a priming agent in cancer immunotherapy. Combinations of radiation with immune checkpoint inhibitors have already proven successful in clinical trials. Therefore, a combination of radiation therapy may have the potential to overcome the current limitations of CAR T cell therapy in solid tumor entities. So far, only limited research was conducted in the area of CAR T cells and radiation. In this review we will discuss the potential and risks of such a combination in the treatment of cancer patients.

Prediction of late allograft dysfunction following liver transplantation by immunological blood biomarkers

BACKGROUND

An accelerated course of hepatic fibrosis may occur in liver transplantation (LT) patients despite normal or slightly abnormal liver blood tests.

AIM

To identify screening tools based on blood biomarkers to predict late allograft dysfunction in LT recipients.

METHODS

174 LT recipients were enrolled. Liver biopsy, liver functional tests, cytokine quantitation in serum, as well as soluble MHC class I polypeptide-related sequence A and B (sMICA/sMICB) and soluble UL16 binding protein 2 (sULBP2) were performed.

RESULTS

Patients with late graft dysfunction had a significantly higher donor age, lower albumin level, higher alanine (ALT) and aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT), total bilirubin and alkaline phosphatase (ALP), higher sMICA, sULBP2, higher interleukin (IL) 6, interferon γ and lower IL10 in serum as compared to recipients without allograft dysfunction. In order to provide a better statistical accuracy for discriminating 5-year allograft dysfunction from other less progressive subtype of allograft injury, we established a predictive model, based on 7 parameters (serum ALP, ALT, AST, GGT, sMICA, IL6 and albumin) which provided an Area Under the Receiver Operating Characteristics (AUROC) curve of 0.905.

CONCLUSIONS

Blood-based biomarkers can significantly improve prediction of late liver allograft outcome in LT patients. The new developed score comprising serum parameters, with an excellent AUROC, can be reliably used for diagnosing late allograft dysfunction in transplanted patients.

Radiation-Induced Immunity and Toxicities: The Versatility of the cGAS-STING Pathway

In the past decade, radiation therapy (RT) entered the era of personalized medicine, following the striking improvements in radiation delivery and treatment planning optimization, and in the understanding of the cancer response, including the immunological response. The next challenge is to identify the optimal radiation regimen(s) to induce a clinically relevant anti-tumor immunity response. Organs at risks and the tumor microenvironment (e.g. endothelial cells, macrophages and fibroblasts) often limit the radiation regimen effects due to adverse toxicities. Here, we reviewed how RT can modulate the immune response involved in the tumor control and side effects associated with inflammatory processes. Moreover, we discussed the versatile roles of tumor microenvironment components during RT, how the innate immune sensing of RT-induced genotoxicity, through the cGAS-STING pathway, might link the anti-tumor immune response, radiation-induced necrosis and radiation-induced fibrosis, and how a better understanding of the switch between favorable and deleterious events might help to define innovative approaches to increase RT benefits in patients with cancer.

A distinguishing profile of chemokines, cytokines, and biomarkers in the saliva of children with Sjögren's syndrome

Objective

SS is an autoimmune disease most commonly diagnosed in adults but can occur in children. Our objective was to assess the presence of chemokines, cytokines and biomarkers (CCBMs) in saliva from these children that were associated with lymphocyte and mononuclear cell functions.

Methods

Saliva was collected from 11 children diagnosed with SS prior to age 18 years and 16 normal healthy children. A total of 105 CCBMs were detected in multiplex microparticle-based immunoassays. ANOVA and t test (0.05 level) were used to detect differences. Ingenuity Pathway Analysis (IPA) was used to assess whether elevated CCBMs were in annotations associated with immune system diseases and select leukocyte activities and functions. Machine learning methods were used to evaluate the predictive power of these CCBMs for SS and were measured by receiver operating characteristic (ROC) curve and area under curve (AUC).

Results

Of the 105 CCBMs detected, 43 (40.9%) differed in children with SS from those in healthy study controls (P < 0.05) and could differentiate the two groups (P < 0.05). Elevated CCBMs in IPA annotations were associated with autoimmune diseases and with leukocyte chemotaxis, migration, proliferation, and regulation of T cell activation. The best AUC value in ROC analysis was 0.93, indicating that there are small numbers of CCBMs that may be useful for diagnosis of SS.

Conclusion

While 35 of these 43 CCBMs have been previously reported in SS, 8 CCBMs had not. Additional studies focusing on these CCBMs may provide further insight into disease pathogenesis and may contribute to diagnosis of SS in children.

Shaping of CD56bri Natural Killer Cells in Patients With Steroid-Refractory/Resistant Acute Graft-vs.-Host Disease via Extracorporeal Photopheresis

CD56^bri natural killer (NK) cells play an important role in the pathogenesis of graft-vs. -host disease (GVHD) and immune defense in the early period after allogeneic hematopoietic stem cell transplantation. Extracorporeal photopheresis (ECP) as an immunomodulating therapy has been widely used for GVHD treatment. However, the mechanism of action of ECP still remains to be elucidated, particularly the influence of ECP on NK cells. Thirty-four patients with steroid-refractory/resistant acute GVHD (aGVHD) ≥ °II and moderate to severe chronic GVHD (cGVHD) received ECP therapy. Patient samples obtained during intensive and long-term treatment were analyzed. Immunomonitoring with respect to cell phenotype and function was performed on rested peripheral blood mononuclear cells (PBMCs) using multiparametric flow cytometry. NK activity in terms of cytokine release was analyzed by intracellular cytokine staining after co-culture with K562 cells. Moreover, the proliferative capacity of NK cells, CD4⁺, and CD8⁺ T cells was determined by carboxyfluorescein succinimidyl ester (CFSE) staining. Clinically, 75% of aGVHD and 78% of cGVHD patients responded to ECP therapy. Moreover, our data show that aGVHD, cGVHD patients and healthy donors (HDs) present distinct NK patterns: aGVHD patients have a higher frequency of CD56^bri NK subsets with stronger NKG2D and CD62L expression, while CD56⁻CD16⁺ NK cells with higher expression of CD57 and CD11b stand out as a signature population for cGVHD. ECP therapy could significantly decrease CD56^briCD16⁻ NK cells with shifting the quality from a cytotoxic to a regulatory pattern and additionally mature CD56^dim NK cells via upregulation of CD57 in complete responding aGVHD patients. Moreover, ECP could keep the anti-viral and anti-leukemic effects intact via maintaining specialized anti-viral/leukemic CD57⁺NKG2C⁺CD56^dim NK cells as well as remaining the quality and quantity of cytokine release by NK cells. The proliferative capacity of effector cells remained constant over ECP therapy. In conclusion, ECP represents an attractive option to treat GVHD without compromising anti-viral/leukemic effects. Shaping of CD56^bri NK cell compartment by downregulating the cytotoxic subset while upregulating the regulatory subset contributes to the mechanisms of ECP therapy in aGVHD.

IFN-γ Regulates the Expression of MICA in Human Corneal Epithelium Through miRNA4448 and NFκB

Purpose

Major histocompatibility complex class I-related chain A (MICA), a non-classical major histocompatibility complex molecule, can stimulate or co-stimulate CD8+ T cells or natural killer (nk) cells, thus affecting cornea allograft survival. This study investigated IFN-γ regulation of MICA expression levels in human corneal epithelium by miRNA4448.

Methods

MICA expression levels in human corneal epithelial cells (HCECs) stimulated with IFN-γ were detected by qRT-PCR and an enzyme-linked immunosorbent assay, and differential miRNA expression levels were measured. qRT-PCR, Western blotting, and immunofluorescence staining revealed nuclear factor kappa B (NFκB)/P65 expression in IFN-γ-treated and miRNA4448-overexpressed HCECs. A luciferase reporter assay was used to predict the interaction between NFκB and MICA. Additionally, HCECs were transfected with MICA plasmid or treated with IFN-γ and NKG2D-mAb and cocultured with NK cells and CD8+ T cells. Cell apoptosis was measured using Annexin V/PI staining. qRT-PCR detected the expression of anti-apoptosis factor Survivin and apoptosis factor Caspase 3 in MICA-transfected and IFN-γ-treated HCECs after co-culturing with NK cells and CD8+ T cells.

Results

IFN-γ (500 ng/ml, 24 h) upregulated MICA expression in HCECs in vitro. Among six differentially expressed microRNAs, miRNA4448 levels decreased the most after IFN-γ treatment. The overexpression of miRNA4448 decreased MICA expression. miRNA4448 downregulated NFκB/P65 expression in IFN-γ-induced HCEC, and it was determined that NFκB/P65 directly targeted MICA by binding to the promotor region. A coculture with NK cells and CD8+ T cells demonstrated that MICA overexpression enhanced HCEC apoptosis, which could be inhibited by NKG2D-mAb. Simultaneously, Survivin mRNA expression decreased and Caspase3 mRNA expression increased upon the interaction between MICA and NK (CD8+ T) cells in HCECs.

Conclusion

IFN-γ enhances the expression of MICA in HCECs by modulating miRNA4448 and NFκB/P65 levels, thereby contributing to HCEC apoptosis induced by NK and CD8+ T cells. This discovery may lead to new insights into the pathogenesis of corneal allograft rejection.

The histone deacetylase inhibitor SAHA simultaneously reactivates HIV-1 from latency and up-regulates NKG2D ligands sensitizing for natural killer cell cytotoxicity

In pilot HIV-1 eradication studies, patients' immune responses were ineffective at killing viral reservoirs reactivated through latency reversing agents (LRAs) like suberoylanilide hydroxamic acid (SAHA). We hypothesized that T cells harboring reactivated HIV-1 express MIC and ULBP ligands for the activating NKG2D receptor of natural killer (NK) cells. Here, we demonstrated that MICA/B and ULBP2 are induced by SAHA on primary T cells harboring reactivated virus. Using latently HIV-1-infected J-Lat 6.3/8.4/9.2 and J1.1 cell lines, we showed that SAHA reverts latency and, simultaneously, up-regulates MICA/B and ULBP2 acting at the transcriptional level and through ATR activation, thus sensitizing T cells with reactivated virus to NKG2D-mediated killing by NK cells. Moreover, IL-2 and IL-15 potently boosted NKG2D expression and cytotoxicity of NK cells against SAHA-reactivated p24⁺ target cells. Therefore, immunotherapy with cytokines enhancing NKG2D-mediated NK-cell cytotoxicity combined with administration of LRAs up-modulating NKG2D ligands, represents a promising approach towards HIV-1 eradication.

Efficient killing of radioresistant breast cancer cells by cytokine-induced killer cells

Recurrence of breast cancer after radiotherapy may be partly explained by the presence of radioresistant cells. Thus, it would be desirable to develop an effective therapy against radioresistant cells. In this study, we demonstrated the intense antitumor activity of cytokine-induced killer cells against MCF-7 and radioresistant MCF-7 cells, as revealed by cytokine-induced killer-mediated cytotoxicity, tumor cell proliferation, and tumor invasion. Radioresistant MCF-7 cells were more susceptible to cytokine-induced killer cell killing. The stronger cytotoxicity of cytokine-induced killer cells against radioresistant MCF-7 cells was dependent on the expression of major histocompatibility complex class I polypeptide-related sequence A/B on radioresistant MCF-7 cells after exposure of cytokine-induced killer cells to sensitized targets. In addition, we demonstrated that cytokine-induced killer cell treatment sensitized breast cancer cells to chemotherapy via the downregulation of TK1, TYMS, and MDR1. These results indicate that cytokine-induced killer cell treatment in combination with radiotherapy and/or chemotherapy may induce synergistic antitumor activities and represent a novel strategy for breast cancer.

Genetic Association of Hematopoietic Stem Cell Transplantation Outcome beyond Histocompatibility Genes

The outcome of hematopoietic stem cell transplantation (HSCT) is controlled by genetic factors among which the leukocyte antigen human leukocyte antigen (HLA) matching is most important. In addition, minor histocompatibility antigens and non-HLA gene polymorphisms in genes controlling immune responses are known to contribute to the risks associated with HSCT. Besides single-nucleotide polymorphisms (SNPs) in protein coding genes, SNPs in regulatory elements such as microRNAs (miRNAs) contribute to these genetic risks. However, genetic risks require for their realization the expression of the respective gene or miRNA. Thus, gene and miRNA expression studies may help to identify genes and SNPs that indeed affect the outcome of HSCT. In this review, we summarize gene expression profiling studies that were performed in recent years in both patients and animal models to identify genes regulated during HSCT. We discuss SNP–mRNA–miRNA regulatory networks and their contribution to the risks associated with HSCT in specific examples, including forkheadbox protein 3 and regulatory T cells, the role of the miR-155 and miR-146a regulatory network for graft-versus-host disease, and the function of MICA and its receptor NKG2D for the outcome of HSCT. These examples demonstrate how SNPs affect expression or function of proteins that modulate the alloimmune response and influence the outcome of HSCT. Specific miRNAs targeting these genes and directly affecting expression of mRNAs are identified. It might be valuable in the future to determine SNPs and to analyze miRNA and mRNA expression in parallel in cohorts of HSCT patients to further elucidate genetic risks of HSCT.

Natural Killer Group 2, Member D/NKG2D Ligands in Hematopoietic Cell Transplantation

Natural killer group 2, member D (NKG2D) is an invariant activatory receptor present on subsets of natural killer and T lymphocytes. It stimulates the cytolytic effector response upon engagement of its various stress-induced ligands NKG2D ligands (NKG2DL). Malignant transformation and conditioning treatment prior to hematopoietic cell transplantation (HCT) are stress factors leading to the activation of the NKG2D/NKG2DL signaling in clinical settings. In the context of HCT, NKG2D-bearing cells can kill both tumor and healthy cells expressing NKG2DL. The NKG2D/NKG2DL engagement has therefore a key role in the regulation of one of the most salient issues in allogeneic HCT, i.e., maintaining a balance between graft-vs.-leukemia effect and graft-vs.-host disease. The present review summarizes the current state of our knowledge pertaining to the role of the NKG2D and NKG2DL in HCT.

Matching for the nonconventional MHC-I MICA gene significantly reduces the incidence of acute and chronic GVHD

Graft-versus-host disease (GVHD) is among the most challenging complications in unrelated donor hematopoietic cell transplantation (HCT). The highly polymorphic MHC class I chain-related gene A, MICA, encodes a stress-induced glycoprotein expressed primarily on epithelia. MICA interacts with the invariant activating receptor NKG2D, expressed by cytotoxic lymphocytes, and is located in the MHC, next to HLA-B Hence, MICA has the requisite attributes of a bona fide transplantation antigen. Using high-resolution sequence-based genotyping of MICA, we retrospectively analyzed the clinical effect of MICA mismatches in a multicenter cohort of 922 unrelated donor HLA-A, HLA-B, HLA-C, HLA-DRB1, and HLA-DQB1 10/10 allele-matched HCT pairs. Among the 922 pairs, 113 (12.3%) were mismatched in MICA MICA mismatches were significantly associated with an increased incidence of grade III-IV acute GVHD (hazard ratio [HR], 1.83; 95% confidence interval [CI], 1.50-2.23; P < .001), chronic GVHD (HR, 1.50; 95% CI, 1.45-1.55; P < .001), and nonelapse mortality (HR, 1.35; 95% CI, 1.24-1.46; P < .001). The increased risk for GVHD was mirrored by a lower risk for relapse (HR, 0.50; 95% CI, 0.43-0.59; P < .001), indicating a possible graft-versus-leukemia effect. In conclusion, when possible, selecting a MICA-matched donor significantly influences key clinical outcomes of HCT in which a marked reduction of GVHD is paramount. The tight linkage disequilibrium between MICA and HLA-B renders identifying a MICA-matched donor readily feasible in clinical practice.

The MICA-129 dimorphism affects NKG2D signaling and outcome of hematopoietic stem cell transplantation

The MHC class I chain-related molecule A (MICA) is a highly polymorphic ligand for the activating natural killer (NK)-cell receptor NKG2D. A single nucleotide polymorphism causes a valine to methionine exchange at position 129. Presence of a MICA-129Met allele in patients (n = 452) undergoing hematopoietic stem cell transplantation (HSCT) increased the chance of overall survival (hazard ratio [HR] = 0.77, P = 0.0445) and reduced the risk to die due to acute graft-versus-host disease (aGVHD) (odds ratio [OR] = 0.57, P = 0.0400) although homozygous carriers had an increased risk to experience this complication (OR = 1.92, P = 0.0371). Overall survival of MICA-129Val/Val genotype carriers was improved when treated with anti-thymocyte globulin (HR = 0.54, P = 0.0166). Functionally, the MICA-129Met isoform was characterized by stronger NKG2D signaling, triggering more NK-cell cytotoxicity and interferon-γ release, and faster co-stimulation of CD8⁺ T cells. The MICA-129Met variant also induced a faster and stronger down-regulation of NKG2D on NK and CD8⁺ T cells than the MICA-129Val isoform. The reduced cell surface expression of NKG2D in response to engagement by MICA-129Met variants appeared to reduce the severity of aGVHD.

Genetics, genomics, and evolutionary biology of NKG2D ligands

Human and mouse NKG2D ligands (NKG2DLs) are absent or only poorly expressed by most normal cells but are upregulated by cell stress, hence, alerting the immune system in case of malignancy or infection. Although these ligands are numerous and highly variable (at genetic, genomic, structural, and biochemical levels), they all belong to the major histocompatibility complex class I gene superfamily and bind to a single, invariant, receptor: NKG2D. NKG2D (CD314) is an activating receptor expressed on NK cells and subsets of T cells that have a key role in the recognition and lysis of infected and tumor cells. Here, we review the molecular diversity of NKG2DLs, discuss the increasing appreciation of their roles in a variety of medical conditions, and propose several explanations for the evolutionary force(s) that seem to drive the multiplicity and diversity of NKG2DLs while maintaining their interaction with a single invariant receptor.

In situ vaccination by radiotherapy to improve responses to anti-CTLA-4 treatment

Targeting immune checkpoint receptors has emerged as an effective strategy to induce immune-mediated cancer regression in the subset of patients who have significant pre-existing anti-tumor immunity. For the remainder, effective anti tumor responses may require vaccination. Radiotherapy, traditionally used to achieve local tumor control, has acquired a new role, that of a partner for immunotherapy. Ionizing radiation has pro-inflammatory effects that facilitate tumor rejection. Radiation alters the tumor to enhance the concentration of effector T cells via induction of chemokines, cytokines and adhesion molecules. In parallel, radiation can induce an immunogenic death of cancer cells, promoting cross-presentation of tumor-derived antigens by dendritic cells to T cells. Newly generated anti-tumor immune responses have been demonstrated post-radiation in both murine models and occasional patients, supporting the hypothesis that the irradiated tumor can become an in situ vaccine. It is in this role, that radiation can be applied to induce anti-tumor T cells in lymphocyte-poor tumors, and possibly benefit patients who would otherwise fail to respond to immune checkpoint inhibitors. This review summarizes preclinical and clinical data demonstrating that radiation acts in concert with antibodies targeting the immune checkpoint cytotoxic T-lymphocyte antigen-4 (CTLA-4), to induce therapeutically effective anti-tumor T cell responses in tumors otherwise non responsive to anti-CTLA-4 therapy.

Immunogenetic biomarkers in inflammatory bowel diseases: Role of the IBD3 region

Many studies have demonstrated the linkage between the IBD3 region (6p21.1-23), an area which encompasses the famous human leukocyte antigen (HLA) complex, and Crohn’s disease (CD) or ulcerative colitis (UC). IBD3 is the only region that meets genome-wide significance, and provides stronger evidence of the linkage than 16p13.1-16q12.2 (IBD1), the locus that contains the susceptibility gene CARD15. However, despite these findings, IBD3 susceptibility genes remain elusive and unclear due to the strong linkage disequilibrium, extensive polymorphism, and high gene density that characterize this area and also due to varying allele frequencies in populations around the world. This area presents an extremely high abundance of genes, including the classical and non-classical major histocompatibility complex (MHC) class I and II genes, and other genes, namely MHC class III genes tumor necrosis factor (TNF)-α and -β, and Hsp, whose proteins play key functions in immunological processes. To date, it is not clear which genes within the MHC family contribute to the IBD pathogenesis, although certain HLA alleles have been associated with IBD. Recent insights into the biological function of other genes encoded within the IBD3 region, such as the MHC class I chain-related (MIC) genes, have led investigators to a more comprehensive exploration of this region. MHC class I chain-related molecule A (MICA) is highly polymorphic and interacts with NKG2D, its receptor on the surface of NK, Tγδ and T CD8⁺ cells. Increased expression of MICA in intestinal epithelial cells and increased expression of NKG2D in CD4⁺ T cells (lamina propria) in patients with CD have also been reported. MICA alleles have also been associated with IBD, and a variation at amino acid position 129 of the α2-heavy chain domain seems to categorize MICA alleles into strong and weak binders of NKG2D receptor, thereby influencing the effector cells’ function. In this regard, a relevant role of MICA-129-Val/Met single nucleotide polymorphism has recently been implicated in the pathogenesis of IBD. TNF-α and -β also play an important role in inflammatory response. In fact, IBD is commonly treated with TNF-α inhibitors. Additionally, polymorphisms of TNF-α gene are known to affect the gene expression level and particular TNF-α genotypes may influence the response of IBD patients treated with TNF-α inhibitors.

Radiation-induced autophagy potentiates immunotherapy of cancer via up-regulation of mannose 6-phosphate receptor on tumor cells in mice

There is a significant body of evidence demonstrating that radiation therapy (XRT) enhances the effect of immune therapy. However, the precise mechanisms by which XRT potentiates the immunotherapy of cancer remain elusive. Here, we report that XRT potentiates the effect of immune therapy via induction of autophagy and resultant trafficking of mannose-6-phopsphate receptor (MPR) to the cell surface. Irradiation of different tumor cells caused substantial up-regulation of MPR on the cell surface in vitro and in vivo. Down-regulation of MPR in tumor cells with shRNA completely abrogated the combined effect of XRT and immunotherapy (CTLA4 antibody) in B16F10-bearing mice without changes in the tumor-specific responses of T cells. Radiation-induced MPR up-regulation was the result of redistribution of the receptor to the cell surface. This effect was caused by autophagy with redirection of MPR to autophagosomes in a clathrin-dependent manner. In autophagosomes, MPR lost its natural ligands, which resulted in subsequent trafficking of empty receptor(s) back to the surface. Together, our data demonstrated a novel mechanism by which XRT can enhance the effect of immunotherapy and the molecular mechanism of this process.

Enhanced sensitivity of colon tumour cells to natural killer cell cytotoxicity after mild thermal stress is regulated through HSF1-mediated expression of MICA

PURPOSE

Previously we showed that mild thermal stress increased natural killer (NK) cell-mediated tumour cytotoxicity and that this could be blocked by anti-NKG2D or anti-MICA (major histolocompatability complex (MHC) class I related chain A) antibodies. Here, we investigated the role of the transcription factor heat shock factor 1 (HSF1) in thermal regulation of MICA expression in tumour cells in vitro and in vivo.

MATERIALS AND METHODS

Hyperthermia experiments were conducted in vitro and in mice using a target temperature of 39.5 °C. Apoptotic cells and NK cells in situ were visualised by use of the TUNEL assay or expression of NKp46 respectively. Using Colo205 cells, HSF1 message was blocked utilising siRNA while luciferase reporter assays were used to measure the activity of the MICA promoter in vitro. Cell surface MICA was measured by flow cytometry.

RESULTS

Following whole body hyperthermia (WBH), tumour tissues showed an increase in NK cells and apoptosis. Mild thermal stress resulted in a transient increase in surface MICA and enhanced NK cytotoxicity of the Colo205 colon cancer cell line. Silencing (mRNA) HSF1 expression in Colo205 cells prevented the thermal enhancement of MICA message and surface protein levels, with partial loss of thermally enhanced NK cytotoxicity. Mutations of the HSF1 binding site on the MICA promoter implicated HSF1 in the thermal enhancement of MICA. Some, but not all, patient-derived colon tumour derived xenografts also exhibited an enhanced MICA message expression after WBH.

CONCLUSIONS

Up-regulation of MICA expression in Colo205 cells and enhanced sensitivity to NK cell killing following mild thermal stress is dependent upon HSF1.

Role of HLA, KIR, MICA, and cytokines genes in leprosy

Many genes including HLA, KIR, and MICA genes, as well as polymorphisms in cytokines have been investigated for their role in infectious disease. HLA alleles may influence not only susceptibility or resistance to leprosy, but also the course of the disease. Some combinations of HLA and KIR may result in negative as well as positive interactions between NK cells and infected host cells with M. leprae, resulting in activation or inhibition of NK cells and, consequently, in death of bacillus. In addition, studies have demonstrated the influence of MICA genes in the pathogenesis of leprosy. Specifically, they may play a role in the interaction between NK cells and infected cells. Finally, pro- and anti-inflammatory cytokines have been influencing the clinical course of leprosy. Data from a wide variety of sources support the existence of genetic factors influencing the leprosy pathogenesis. These sources include twin studies, segregation analyses, family-based linkage and association studies, candidate gene association studies, and, most recently, genome-wide association studies (GWAS). The purpose of this brief review was to highlight the importance of some immune response genes and their correlation with the clinical forms of leprosy, as well as their implications for disease resistance and susceptibility.

Regulation of self-ligands for activating natural killer cell receptors

Natural killer (NK) cells are able to lyse infected and tumor cells while sparing healthy cells. Recognition of diseased cells by NK cells is governed by several activating and inhibitory receptors. We review numerous pathways that have been implicated in the regulation of self-ligands for activating receptors, including NKG2D, DNAM-1, LFA-1, NKp30, NKp44, NKp46, NKp65, and NKp80 found on NK cells and some T cells. Understanding how the regulation of self-encoded ligand expression is regulated may provide novel avenues for future therapeutic approaches to infections and cancer.

The uncertain role of unmodified mesenchymal stem cells in tumor progression: what master switch?

Mesenchymal stem cells (MSCs) are emerging as promising gene vectors for cancer therapy because of their unique characteristics, including the ease of their expansion and genetic modification and their remarkable tumor-tropic properties. However, there remains a concern that MSCs may promote cancer progression. Surprisingly, there are conflicting reports within the literature describing both the promotion and inhibition of cancer progression by MSCs. The reasons for this discrepancy are still unknown. The surface markers, differentiation ability, and tumorigenic roles of MSCs, as well as their effect on immunoregulation, produce heterogeneity. In this review, we describe the heterogeneity of MSCs by the species from which they are derived, the methodology for their isolation and the context of their interactions with cancer cells. The conflicting roles of MSCs in tumor progression may be attributable to the bimodal effect of unmodified MSCs on immunoregulation. MSCs have been reported to suppress T-cell function and inhibit graft-versus-host disease (GVHD). On the other hand, MSCs elicit the graft-versus-tumor (GVT) effect in some cases. Selective allodepletion may be used to dissociate GVHD from the GVT effect. Understanding the conditions that balance GVHD and the GVT effect of MSCs may be crucial to advance cancer therapy research with respect to MSCs.

DNA demethylation and histone H3K9 acetylation determine the active transcription of the NKG2D gene in human CD8+ T and NK cells

The human activating receptor NKG2D is mainly expressed by NK, NKT, γδ T and CD8(+) T cells and, under certain conditions, by CD4(+) T cells. This receptor recognizes a diverse family of ligands (MICA, MICB and ULBPs 1-6) leading to the activation of effector cells and triggering the lysis of target cells. The NKG2D receptor-ligand system plays an important role in the immune response to infections, tumors, transplanted graft and autoantigens. Elucidation of the regulatory mechanisms of NKG2D is therefore essential for therapeutic purposes. In this study, we speculate whether epigenetic mechanisms, such as DNA methylation and histone acetylation, participate in NKG2D gene regulation in T lymphocytes and NK cells. DNA methylation in the NKG2D gene was observed in CD4(+) T lymphocytes and T cell lines (Jurkat and HUT78), while this gene was unmethylated in NKG2D-positive cells (CD8(+) T lymphocytes, NK cells and NKL cell line) and associated with high levels of histone H3 lysine 9 acetylation (H3K9Ac). Treatment with the histone acetyltransferase (HAT) inhibitor curcumin reduces H3K9Ac levels in the NKG2D gene, downregulates NKG2D transcription and leads to a marked reduction in the lytic capacity of NKG2D-mediated NKL cells. These findings suggest that differential NKG2D expression in the different cell subsets is regulated by epigenetic mechanisms and that its modulation by epigenetic treatments might provide a new strategy for treating several pathologies.

Treatment failure in patients with HPV 16-induced vulvar intraepithelial neoplasia: understanding different clinical responses to immunotherapy

Failure of the immune system to launch a strong and effective immune response to high-risk HPV is related to viral persistence and the development of anogenital (pre)malignant lesions such as vulvar intraepithelial neoplasia (VIN). Different forms of immunotherapy, aimed at overcoming the inertia of the immune system, have been developed and met with clinical success. Unfortunately these, in principal successful, therapeutic approaches also fail to induce clinical responses in a substantial number of cases. In this review, the authors summarize the traits of the immune response to HPV in healthy individuals and in patients with HPV-induced neoplasia. The potential mechanisms involved in the escape of HPV-induced lesions from the immune system indicate gaps in our knowledge. Finally, the interaction between the immune system and VIN is discussed with a special focus on the different forms of immunotherapy applied to treat VIN and the potential causes of therapy failure. The authors conclude that there are a number of pre-existing conditions that determine the patients' responsiveness to immunotherapy. An immunotherapeutic strategy in which different aspects of immune failure are attacked by complementary approaches, will improve the clinical response rate.

Dacarbazine-mediated upregulation of NKG2D ligands on tumor cells activates NK and CD8 T cells and restrains melanoma growth

Dacarbazine (DTIC) is a cytotoxic drug widely used for melanoma treatment. However, the putative contribution of anticancer immune responses in the efficacy of DTIC has not been evaluated. By testing how DTIC affects host immune responses to cancer in a mouse model of melanoma, we unexpectedly found that both natural killer (NK) and CD8(+) T cells were indispensable for DTIC therapeutic effect. Although DTIC did not directly affect immune cells, it triggered the upregulation of NKG2D ligands on tumor cells, leading to NK cell activation and IFNγ secretion in mice and humans. NK cell-derived IFNγ subsequently favored upregulation of major histocompatibility complex class I molecules on tumor cells, rendering them sensitive to cytotoxic CD8(+) T cells. Accordingly, DTIC markedly enhanced cytotoxic T lymphocyte antigen 4 inhibition efficacy in vivo in an NK-dependent manner. These results underscore the immunogenic properties of DTIC and provide a rationale to combine DTIC with immunotherapeutic agents that relieve immunosuppression in vivo.

Role of stress-induced NKG2D ligands in liver diseases

Cell death by apoptosis is a prominent feature in a variety of liver diseases. It is likely that apoptosis is the initial cellular response to hepatocyte and biliary injury, which then leads to the initiation of cellular and cytokine cascades culminating in hepatocyte death with subsequent fibrosis and cirrhosis. This sequence of events is of paramount clinical importance. Recently, soluble forms of the major histocompatibility complex class I-related chains A and closely related B (MIC A and B) were reported to be increased in patients with a variety of liver diseases. MIC A and B are cell surface glycoproteins that function as indicators for cellular stress and thus activate circulating cytotoxic natural killer (NK) cells. The interaction between MIC A and B with their cognate receptor natural killer group 2 member D (NKG2D) culminates in enhanced liver cell death, which is mediated in part by apoptotic mechanisms. The present overview focuses on the role of the stress-induced NKG2D ligands MIC A and B in diverse liver diseases. Critical insights into these complex relations may help to promote rationally based therapies in liver diseases. Importantly, we hope that this overview will help to stimulate further studies into mechanisms by which stress ligands mediate cell death and its sequale.

Overexpression of IL-32alpha increases natural killer cell-mediated killing through up-regulation of Fas and UL16-binding protein 2 (ULBP2) expression in human chronic myeloid leukemia cells

IL-32 was recently identified as a proinflammatory cytokine that is induced by IL-18 in natural killer (NK) cells and is highly correlated with inflammatory disorders. However, the relationship between IL-32 and tumor progression is still unknown. In this study, we investigated whether overexpression of IL-32 affects susceptibility of chronic myeloid leukemia (CML) cells to NK cells. Interestingly, IL-32α-overexpressing CML cell lines, K562, Kcl22, and BV173, showed higher NK cell-mediated killing. Flow cytometry analysis revealed that overexpression of IL-32α induced increased expression of Fas and UL16-binding protein 2 (ULBP2) in CML cells. The direct relationship between overexpression of surface molecules by IL-32α and increased NK cell-mediated killing was confirmed by Fas or ULBP2 siRNA transfection. IL-32α-induced Fas and ULBP2 expression are regulated p38 MAPK. In addition, the transcription factor Ets1 plays a key role in ULBP2 specific expression by IL-32α overexpression in ULBP family members. Taken together, these data show that IL-32α stimulates Fas and ULBP2 expression via activation of p38 MAPK, which increases NK susceptibility of CML cells. Enhanced NK cell susceptibility of CML cells by IL-32α overexpression may improve the efficiency of NK cell-based immunotherapy.

Association analysis of MICA gene polymorphism and MICA-129 dimorphism with inflammatory bowel disease susceptibility in a Spanish population

MICA is located at 46 kb centromeric of HLA-B, is highly polymorphic and interactions with NKG2D, its receptor on the surface of NK, Tgammadelta, and T CD8 lymphocytes. A variation at amino acid position 129 of the alpha2-heavy chain domain seems to categorize MICA alleles into strong and weak binder of NKG2D receptor, and thereby to influence effector cell function. Our aim was to study allele polymorphism of MICA and the functionally relevant dimorphism (129val/met) of MICA gene in inflammatory bowel disease (IBD) patients in our population. DNA was obtained from IBD patients (n = 88) and unrelated healthy Murcians (n = 154) and used to MICA genotyping using polymerase chain reaction-sequence-specific oligonucleotides. We did not find statistical differences in the distribution of MICA alleles between the IBD and control groups. However, we found a higher frequency of MICA-129met/met and a lower frequency of MICA-129val/met genotypes in IBD patients (mainly in ulcerative colitis) than in controls (pc = 0.02). These preliminary data could suggest a relevant role of MICA-129-val/met SNP (weak/strong binders of NKG2D receptor) in the pathogenesis of IBD.

Donor-recipient mismatches in MHC class I chain-related gene A in unrelated donor transplantation lead to increased incidence of acute graft-versus-host disease

The polymorphic products of major histocompatibility complex class I-related chain A (MICA) genes are important in solid organ transplantation rejection. MICA expression is limited to gut epithelium and may play a role in triggering acute graft-versus-host disease (aGVHD). A total of 236 recipients of unrelated donor transplantation were studied. Donor-recipient human leukocyte antigen (HLA) match was 10/10 human leukocyte antigen (HLA-A, -B, -C, -DRB1, -DQB1) in 73% and MICA mismatch in 8.4%. Because of physical vicinity of the loci, MICA mismatch was significantly associated with mismatch at HLA-B and HLA-C. A higher rate of grade II-IV aGVHD was seen in MICA-mismatched patients (80% vs 40%, P = .003) irrespective of degree of HLA matching (HLA 10/10 match: 75% vs 39%, P = .02) and HLA any mismatch (83% vs 46%, P = .003). The rate of grade II-IV gastrointestinal aGVHD was also higher in MICA-mismatched patients (35% vs 17%, P = .05). We conclude that MICA may represent novel a transplantation antigen recognized by human allogeneic T cells. This study was registered at ClinicalTrials.gov (Identifier NCT00506922).

Innate T cell responses in human gut

One arm of the gut-associated immune system is represented by a vast collection of T lymphocytes which participate in the subtle interplay between innate and adaptive immune mechanisms and maintain homeostasis at the main body external surface. Mounting data are providing exciting new insight into the innate-like mechanisms which enable intestinal T cells to rapidly sense local conditions and which broaden the spectrum of their functions and regulation at this strategic location. Herein we discuss how innate-like T cell recognition by unconventional T cell subsets and expression of innate NK receptors might modulate immune T cell responses in the human normal or diseased intestine.

Oncostatin M enhances the antiviral effects of type I interferon and activates immunostimulatory functions in liver epithelial cells

Oncostatin M (OSM) is released together with type I interferon (IFN) by activated dendritic cells, suggesting a concerted action of these cytokines in the biological response against infection. We found that OSM increases the antiviral effect of IFN-alpha in Huh7 hepatoma cells infected with hepatitis A or hepatitis C virus and synergizes with IFN-alpha in the induction of antiviral genes. The combination of OSM and IFN-alpha led to upregulation of both STAT1 and STAT3 together with intense and prolonged activation of STAT1, STAT3, and Jak1. OSM with or without IFN-alpha also activated p38 mitogen-activated protein kinase, which is known to enhance transcription of IFN-alpha-inducible genes. Interestingly, OSM combined with IFN-alpha strongly induced immunoproteasome genes and other genes involved in antigen processing and presentation. Moreover, OSM, alone or in combination with IFN-alpha, upregulated relevant innate immunity molecules and increased the expression of intracellular adhesion molecule 1 and interleukin-15 receptor alpha (IL-15Ralpha) in liver cells. Hepatoma cells transfected with a plasmid encoding a viral antigen were able to activate effector T cells when pretreated with IFN-alpha plus OSM but not with each cytokine separately. Also, OSM, more than IFN-alpha, augmented the ability of Huh7 cells to transpresent IL-15 to responding lymphocytes and increased the immunostimulatory activity of liver epithelial cells by presenting a short viral peptide to sensitized cytotoxic T cells. In conclusion, OSM enhances the antiviral effects of type I interferon and cooperates with it in the induction of adaptive immune responses to pathogens. These findings may have therapeutic implications.

Allelic diversity of MICA gene and MICA/HLA-B haplotypic variation in a population of the Murcia region in southeastern Spain

Major histocompatibility complex class I-related chain A (MICA) is located at 46 kb centromeric of HLA-B. It is highly polymorphic and interacts with NKG2D, its receptor on the surface of NK, Tgammadelta and T CD8 lymphocytes. Data on MICA polymorphism in different populations are still limited. Our aim was to establish allelic diversity of MICA gene and linkage disequilibrium with HLA-B in our population. DNA was obtained from 154 unrelated healthy individuals from the Murcia region in southeastern Spain. HLA-B genotyping was performed using polymerase chain reaction (PCR)-sequence-specific oligonucleotide probes and allele-specific PCR-sequence-specific primers, and MICA genotyping by using PCR-sequence-specific oligonucleotide probes. A total of 19 MICA alleles were detected on this study. MICA*008 was the most frequent allele (25.3%), followed by MICA*002 (16.1%), MICA*004 (14.9%), MICA*001 (7.8%), MICA*009 and MICA*016 (7.1%), and MICA*010 (4.6%). Eleven alleles had frequencies of <1%. In the haplotype analysis, MICA*008-B*0702 was found to be the most common, followed by MICA*004-B*4403 and MICA*001-B*1801, MICA*002-B*3501, MICA*008-B*4402, MICA*004-B*4901, MICA*008-B*0801, and MICA*002-B*3801. The frequency of MICA*010-B*1501, MICA*008-B*1302, MICA*015-B*4501, and MICA*008-B*4001 was remarkable inasmuch as these two last haplotypes have not been reported in Spanish population. Indeed, MICA*016 linked to B*1402 has also not been reported in the literature. In conclusion, the allelic diversity in our population is similar to other Caucasian populations; however we found a series of less frequent alleles, in addition to as-yet-undescribed haplotypic associations in other populations of Caucasian origin.