Hypoimmunogenic human iPSCs expressing HLA-G, PD-L1, and PD-L2 evade innate and adaptive immunity.

BACKGROUND: The human induced pluripotent stem cells (hiPSCs) can generate all the cells composing the human body, theoretically. Therefore, hiPSCs are thought to be a candidate source of stem cells for regenerative medicine. The major challenge of allogeneic hiPSC-derived cell products is their immunogenicity. The hypoimmunogenic cell strategy is allogenic cell therapy without using immune suppressants. Advances in gene engineering technology now permit the generation of hypoimmunogenic cells to avoid allogeneic immune rejection. In this study, we generated a hypoimmunogenic hiPSC (HyPSC) clone that had diminished expression of human leukocyte antigen (HLA) class Ia and class II and expressed immune checkpoint molecules and a safety switch. METHODS: First, we generated HLA class Ia and class II double knockout (HLA class Ia/II DKO) hiPSCs. Then, a HyPSC clone was generated by introducing exogenous ß-2-microglobulin (B2M), HLA-G, PD-L1, and PD-L2 genes, and the Rapamycin-activated Caspase 9 (RapaCasp9)-based suicide gene as a safety switch into the HLA class Ia/II DKO hiPSCs. The characteristics and immunogenicity of the HyPSCs and their derivatives were analyzed. RESULTS: We found that the expression of HLA-G on the cell surface can be enhanced by introducing the exogenous HLA-G gene along with B2M gene into HLA class Ia/II DKO hiPSCs. The HyPSCs retained a normal karyotype and had the characteristics of pluripotent stem cells. Moreover, the HyPSCs could differentiate into cells of all three germ layer lineages including CD45+ hematopoietic progenitor cells (HPCs), functional endothelial cells, and hepatocytes. The HyPSCs-derived HPCs exhibited the ability to evade innate and adaptive immunity. Further, we demonstrated that RapaCasp9 could be used as a safety switch in vitro and in vivo. CONCLUSION: The HLA class Ia/II DKO hiPSCs armed with HLA-G, PD-L1, PD-L2, and RapaCasp9 molecules are a potential source of stem cells for allogeneic transplantation.

Immune cells and checkpoints in pancreatic adenocarcinoma: Association with clinical and pathological characteristics.

INTRODUCTION: Pancreatic adenocarcinoma is an extremely aggressive neoplasm, with many challenges to be overcome in order to achieve a truly effective treatment. It is characterized by a mostly immunosuppressed environment, with dysfunctional immune cells and active immunoinhibitory pathways that favor tumor evasion and progression. Thus, the study and understanding of the tumor microenvironment and the various cells subtypes and their functional capacities are essential to achieve more effective treatments, especially with the use of new immunotherapeutics. METHODS: Seventy cases of pancreatic adenocarcinoma divided into two groups 43 with resectable disease and 27 with unresectable disease were analyzed using immunohistochemical methods regarding the expression of programmed cell death ligand 1 (PD-L1), programmed cell death ligand 2 (PD-L2), and human leukocyte antigen G (HLA-G) molecules as well as the populations of CD4+ and CD8+ T lymphocytes, regulatory T cells (Tregs), and M2 macrophages (MM2). Several statistical tests, including multivariate analyses, were performed to examine how those immune cells and immunoinhibitory molecules impact the evolution and prognosis of pancreatic adenocarcinoma. RESULTS: CD8+ T lymphocytes and M2 macrophages predominated in the group operated on, and PD-L2 expression predominated in the unresectable group. PD-L2 was associated with T stage, lymph node metastasis, and clinical staging, while in survival analysis, PD-L2 and HLA-G were associated with a shorter survival. In the inoperable cases, Tregs cells, MM2, PD-L1, PD-L2, and HLA-G were positively correlated. CONCLUSIONS: PD-L2 and HLA-G expression correlated with worse survival in the cases studied. Tumor microenvironment was characterized by a tolerant and immunosuppressed pattern, mainly in unresectable lesions, where a broad positive influence was observed between immunoinhibitory cells and immune checkpoint proteins expressed by tumor cells.

LILRB1-HLA-G axis defines a checkpoint driving natural killer cell exhaustion in tuberculosis.

Chronic infections, including Mycobacterium tuberculosis (Mtb)-caused tuberculosis (TB), can induce host immune exhaustion. However, the key checkpoint molecules involved in this process and the underlying regulatory mechanisms remain largely undefined, which impede the application of checkpoint-based immunotherapy in infectious diseases. Here, through adopting time-of-flight mass cytometry and transcriptional profiling to systematically analyze natural killer (NK) cell surface receptors, we identify leukocyte immunoglobulin like receptor B1 (LILRB1) as a critical checkpoint receptor that defines a TB-associated cell subset (LILRB1+ NK cells) and drives NK cell exhaustion in TB. Mechanistically, Mtb-infected macrophages display high expression of human leukocyte antigen-G (HLA-G), which upregulates and activates LILRB1 on NK cells to impair their functions by inhibiting mitogen-activated protein kinase (MAPK) signaling via tyrosine phosphatases SHP1/2. Furthermore, LILRB1 blockade restores NK cell-dependent anti-Mtb immunity in immuno-humanized mice. Thus, LILRB1-HLA-G axis constitutes a NK cell immune checkpoint in TB and serves as a promising immunotherapy target.

The implication of serum HLA-G in angiogenesis of multiple myeloma.

BACKGROUND: Despite the advances of therapies, multiple myeloma (MM) remains an incurable hematological cancer that most patients experience relapse. Tumor angiogenesis is strongly correlated with cancer relapse. Human leukocyte antigen G (HLA-G) has been known as a molecule to suppress angiogenesis. We aimed to investigate whether soluble HLA-G (sHLA-G) was involved in the relapse of MM. METHODS: We first investigated the dynamics of serum sHLA-G, vascular endothelial growth factor (VEGF) and interleukin 6 (IL-6) in 57 successfully treated MM patients undergoing remission and relapse. The interactions among these angiogenesis-related targets (sHLA-G, VEGF and IL-6) were examined in vitro. Their expression at different oxygen concentrations was investigated using a xenograft animal model by intra-bone marrow and skin grafts with myeloma cells. RESULTS: We found that HLA-G protein degradation augmented angiogenesis. Soluble HLA-G directly inhibited vasculature formation in vitro. Mechanistically, HLA-G expression was regulated by hypoxia-inducible factor-1α (HIF-1α) in MM cells under hypoxia. We thus developed two mouse models of myeloma xenografts in intra-bone marrow (BM) and underneath the skin, and found a strong correlation between HLA-G and HIF-1α expressions in hypoxic BM, but not in oxygenated tissues. Yet when stimulated with IL-6, both HLA-G and HIF-1α could be targeted to ubiquitin-mediated degradation via PARKIN. CONCLUSION: These results highlight the importance of sHLA-G in angiogenesis at different phases of multiple myeloma. The experimental evidence that sHLA-G as an angiogenesis suppressor in MM may be useful for future development of novel therapies to prevent relapse.

Decidual γδT cells of early human pregnancy produce angiogenic and immunomodulatory proteins while also possessing cytotoxic potential.

During pregnancy, the maternal immune system must allow and support the growth of the developing placenta while maintaining the integrity of the mother's body. The trophoblast's unique HLA signature is a key factor in this physiological process. This study focuses on decidual γδT cell populations and examines their expression of receptors that bind to non-classical HLA molecules, HLA-E and HLA-G. We demonstrate that decidual γδT cell subsets, including Vδ1, Vδ2, and double-negative (DN) Vδ1-/Vδ2- cells express HLA-specific regulatory receptors, such as NKG2C, NKG2A, ILT2, and KIR2DL4, each with varying dominance. Furthermore, decidual γδT cells produce cytokines (G-CSF, FGF2) and cytotoxic mediators (Granulysin, IFN-γ), suggesting functions in placental growth and pathogen defense. However, these processes seem to be controlled by factors other than trophoblast-derived non-classical HLA molecules. These findings indicate that decidual γδT cells have the potential to actively contribute to the maintenance of healthy human pregnancy.

Role of HLA-G in tumors and upon COVID-19 infection.

HLA-G expression of tumors and upon viral infections is involved in their immune escape leading to the evasion from both T and NK cell recognition. The underlying mechanisms of HLA-G expression in both pathophysiologic conditions are broad and range from genetic abnormalities to epigenetic, transcriptional and posttranscriptional regulation. This review summarizes the current knowledge of the frequency, regulation and clinical relevance of HLA-G expression upon neoplastic and viral transformation, its interaction with components of the microenvironment as well as its potential as diagnostic marker and/or therapeutic target. In addition, it discusses urgent topics, which have to be addressed in HLA-G research.

Prognostic impact of the bone marrow tumor microenvironment, HLA-I and HLA-Ib expression in MDS and CMML progression to sAML.

Genetic aberrations and immune escape are fundamental in MDS and CMML initiation and progression to sAML. Therefore, quantitative and spatial immune cell organization, expression of immune checkpoints (ICP), classical human leukocyte antigen class I (HLA-I) and the non-classical HLA-Ib antigens were analyzed in 274 neoplastic and 50 non-neoplastic bone marrow (BM) biopsies using conventional and multiplex immunohistochemistry and correlated to publicly available dataset. Higher numbers of tissue infiltrating lymphocytes (TILs) were found in MDS/CMML (8.8%) compared to sAML (7.5%) and non-neoplastic BM (5.3%). Higher T cell abundance, including the CD8+ T cell subset, inversely correlated with the number of pathogenic mutations and was associated with blast BM counts, ICP expression, spatial T cell distribution and improved patients' survival in MDS and CMML. In MDS/CMML, higher PD-1/PD-L1/PD-L2 and HLA-I, but lower HLA-G expression correlated with a significantly better patients' outcome. Moreover, a closer spatial proximity of T cell subpopulations and their proximity to myeloid blasts showed a stronger prognostic impact when compared to TIL numbers. In sAML - the continuum of MDS and CMML - the number of TILs had no impact on prognosis, but higher CD28 and HLA-I expression correlated with a better outcome of sAML patients. This study underlines the independent prognostic value of the tumor microenvironment in MDS/CMML progression to sAML, which shows the most pronounced immune escape. Moreover, new prognostic markers, like HLA-G expression and spatial T cell distribution, were described for the first time, which might also serve as therapeutic targets.

Isolation of serum-derived placental/amnio-chorionic extracellular vesicles across pregnancy by immunoaffinity using PLAP and HLA-G.

In brief: Circulating extracellular vesicles of placental/amniochorionic origin carry placental/amniochorionic proteins and nucleic acids with the potential to facilitate non-invasive diagnosis of pregnancy-related disorders. The study reports an improvised method for the enriched isolation of extracellular vesicles of placental/amniochorionic origin using the two markers, PLAP and HLA-G. Abstract: Extracellular vesicles (EVs) are membrane-bound nanovesicles secreted from the cells into extracellular space and body fluids. They are considered 'fingerprints of parent cells', which can reflect their physiological and functional states. During pregnancy, EVs are produced by the syncytiotrophoblasts and extravillous trophoblasts and are released into the maternal bloodstream. In the present study, placental alkaline phosphatase (PLAP)-specific extracellular vesicles were isolated from maternal serum-derived EVs (SDE) across pregnancy. Transmission electron microscopy and dynamic light scattering analysis showed that the isolated EVs exhibited a spherical morphology with ~30-150 nm size range. Nanoparticle tracking analysis indicated that the concentration of PLAP+ serum-derived EVs (PLAP+-SDE) increased across the gestation. PLAP+-SDE contained DNA with LINE1 promoter methylation pattern. C19 miRNA cluster miRNAs (miR 515-5p, 519e and 520f) were present in PLAP+-SDE along with other miRNAs (miR-133-3p, miR210-3p and miR-223-3p). PLAP+-SDE confirmed the presence of EV markers (CD63 and CD9), along with placental proteins (PLAP and cullin 7). A modified novel strategy to extract an enriched population of circulating placental/amniochorionic EVs was devised employing an additional marker of extravillous trophoblasts, human leukocyte antigen G (HLA-G), along with PLAP. The isolated pooled placental/amniochorionic (PLAP+&HLA-G+) serum-derived EVs (PP-SDE) showed ~two-fold increased protein levels of HLA-G in the third-trimester pregnant women compared to the non-pregnant controls. Future studies will be focused on validation of this novel strategy to isolate an enriched population of placental/amniochorionic EVs to facilitate a better understanding of placental physiology and pathophysiology.

HLA-G isoforms, HLA-C allotype and their expressions differ between early abortus and placenta in relation to spontaneous abortions.

INTRODUCTION: Spontaneous abortion (SAB) affects approximately 10% of clinically recognized pregnancies. Fetal trophobalst invasion and remodeling of maternal spiral arteries is reported to be dependent on crosstalk between HLA-C/HLA-G expressed on extra villous trophoblast (EVTs)and Killer cell Immunoglobin like receptors (KIRs) of decidual NK (dNK). Immune dysfunction in decidua contributes to early miscarriage. METHODOLOGY: The study used mother neonate paired cord blood and term placenta samples (n = 46), elective abortus (n = 17,gestational age = 10-12 weeks of pregnancy) and SAB abortus (n = 24, gestational age = 12-15 weeks of pregnancy) for HLA-G, KIR2D and HLA-C. In addition, term placenta was collected from women with history of spontaneous pregnancy loss (n = 24) and women with history of live birth (n = 32). SSP-PCR was used for genotyping, RT-PCR for gene expression, copy number variation (CNVs) and HLA-C allotyping and ELISA for protein expression studies. RESULTS: Membrane bound HLA-G4 isoform proportion was higher 39.28%, p = 0.02) in term placenta. SAB abortus had higher proportion of HLA-G3 (50%),while elective abortus exhibited higher proportion of soluble isoforms (HLA-G5, = 5.9, HLA-G6 = 5.9%, HLA-G7 = 11.8%). Higher inhibitory KIR2DL1 content and copy numbers with lower HLA-C2 in SAB contrasted with higher copy numbers of KIR2DS1(p = 0.001), KIR2DS1+/2DL1+- HLA-C2 combined genotype in healthy placenta. Elevated KIR2D protein levels (p = 0.001), and concurrently, HLA-C levels were upregulated in healthy placenta. CONCLUSION: Our data supports lower cognate receptor ligand KIR2DS1+/2DL1+ HLA-C2 together with predominance of HLA-G3 isoform in SAB as confounding factors in spontaneous pregnancy loss. HLA-G isoforms and expression differed between first trimester abortus and term placenta suggesting temporal modulation and marks novelty of the study.

Follicular fluid concentration of soluble Human-G Leukocytic Antigen (sHLA-G) in in vitro fertilization cycles of women with and without peritoneal endometriosis.

OBJECTIVE: The objective of this research is to investigate the association between the concentrations of soluble human leukocyte G antigen (sHLA-G) in the follicular fluid (FF) in infertile patients with peritoneal endometriosis submitted to in vitro fertilization. METHODS: We performed a cross-sectional study, including ninety-six women undergoing in vitro fertilization (IVF) ageing ≤ 40 years. Infertile patients were classified into two groups: with endometriosis diagnosed by laparoscopy and without endometriosis due to tubal factor. ELISA measured soluble HLA-G in the FF of a pool of punctured (more than 17mm) follicles from women with endometriosis and without endometriosis who were subjected to ovulation induction for IVF. Embryos obtained after fertilization were classified according to the graduated embryo score (GES). RESULTS: Groups were comparables in terms of age, the number of follicles, AMH, FSH and all included reproductive outcomes. There was no association between sHLA-G concentrations and the average score of the generated embryos (p>0.05). Measurement of sHLA-G in the follicle fluid in women with endometriosis and without endometriosis (tubal factor) showed no significant difference (p>0.05). We also compared sHLA-G per follicle and per embryo, which were not different between both groups (p>0.05). CONCLUSIONS: Patients with peritoneal endometriosis submitted to IVF did not demonstrate an altered sHLA-G in the follicular fluid compared to the follicular fluid sHLA-G concentration in tubal factor patients. Also, this molecule was not linked to any other reproductive outcome.

EGFR, HLA-G, CD70, c-MET, and NY-ESO1 as potential biomarkers in high grade epithelial ovarian carcinoma.

High grade epithelial ovarian carcinoma is an aggressive tumor. Treatment includes platinum therapy, however it recurs in most patients due to therapy resistance. In this project, we study the immunohistochemical (IHC) expression of five potential biomarkers/prognostic markers in high grade epithelial ovarian carcinoma: EGFR, HLA-G, CD70, c-MET, and NY-ESO1. A cohort of 274 patients is used. We compare the IHC expression with age, stage, ascites status, family history of cancer, disease free survival (DFS) and overall survival (OS). EGFR expression is significantly correlated with family history and worse OS. HLA-G is associated with worse OS. To confirm the results of EGFR and HLA-G, a second separated cohort of 248 patients is used. Positive EGFR expression again shows worse OS, while HLA-G expression has worse prognostic trend. CD70 has a worse OS trend. C-MET and NY-ESO1 do not have any clinical correlations. EGFR can potentially serve as target in future clinical immune therapy trials.

IDO-1 impairs antitumor immunity of natural killer cells in triple-negative breast cancer via up-regulation of HLA-G.

BACKGROUND: Triple-negative breast cancers (TNBC) are highly aggressive malignancies with poor prognosis. As an essential enzyme in the tryptophan-kynurenine metabolic pathway, indoleamine 2,3 dioxygenase-1 (IDO-1) has been reported to facilitate immune escape of various tumors. However, the mechanism underlying the immunosuppressive role of IDO-1 in TNBC remains largely uncharacterized. METHODS: We examined the IDO-1 expression in 93 clinical TNBC tissues and paired adjacent normal tissues, and analyzed the regulation role of environmental cytokines like IFN-γ in IDO-1 expression. The effect of IDO-1 expression in TNBC cells on the function of NK cells were then evaluated and the underlying mechanisms were exploited. RESULTS: IDO-1 expressed in 50 of 93 (54.1%) TNBC patients. TNBC patients with high IDO-1 expression tended to have more infiltrated immune cells including NK cells, which are less active than patients with low IDO-1 expression. NK cells could produce IFN-γ, which induced IDO-1 expression in TNBC cells, whereas IDO-1 impaired the cytotoxicity of co-cultured NK cells by upregulation of HLA-G. Blockade of HLA-G improved the antitumor activity of NK cells to TNBC in vivo. CONCLUSION: TNBC cells induce dysfunction of NK cells through an IFN-γ/IDO-1/HLA-G pathway, which provide novel insights into the mechanisms of TNBC progression and demonstrate the applicability of IDO-1 and HLA-G targeting in the treatment of TNBC.

HLA-E and Its Soluble Form as Indicators of a Sex-Specific Immune Response in Patients with Oral Squamous Cell Carcinoma.

The human leukocyte antigene E (HLA-E) is associated with tumorigenesis in various cancers. Immunoncology along with sex-specific aspects in cancer therapy are now in scientific focus. Therefore, immunohistochemical HLA-E expression was retrospectively analysed in a cohort of oral squamous cell carcinomas (OSCC) after surgical therapy. Then, serum concentration of HLA-E (sHLA-E) was quantified in a prospective cohort by enzyme-linked immunosorbent assay. High HLA-E expression was associated with advanced UICC stage (Spearman's correlation: p = 0.002) and worse survival (Cox-regression: progression-free survival: hazard ratio (HR) 3.129, confidence range (CI) 1.443-6.787, p = 0.004; overall survival: HR 2.328, CI 1.071-5.060, p = 0.033). The sHLA-E concentration was significantly higher in the control group than in tumor group (Mann-Whitney U-test (MW-U): p = 0.021). Within the tumor group, women showed significantly higher sHLA-E levels than men (MW-U: p = 0.049). A closer look at the tumor group and the control group showed that gender-specific differences exist: while no differences in sHLA-E concentration were detectable between female subjects of tumor group and control group (MW-U: p = 0.916), male subjects of tumor group had a significantly lower sHLA-E concentration compared to those of control group (MW-U: p = 0.001). In summary, our results provide evidence for sex-specific differences in immune responses in OSCC. This fact should be considered regarding future immunotherapy regimens.

Validation of the Sw71-spheroid model with primary trophoblast cells.

PROBLEM: Human implantation is a limiting factor for the success of natural and IVF reproduction since about 60% of pregnancy losses occur in the peri-implantation period. The in vitro modeling of human implantation challenges the researchers in accurate recreation of the complex in vivo differentiation and function of human blastocyst in the peri-implantation period. In previous studies, we constructed Sw71-spheroid models, which like human blastocyst undergo compactization, attaches to the endometrial epithelium, invade, and migrate. The aim of this study was to validate the trophoblast Sw71-spheroid model with primary trophoblast cells, derived from healthy women in early pregnancy. METHOD OF STUDY: We performed a direct comparison of Sw71-spheroid model with placenta-derived primary trophoblasts regarding their hybrid phenotype and HLA status, as well as the ability to generate spheroids able to migrate and invade. From the primary trophoblast cells, isolated by mild enzymatic treatment and Percoll gradient separation, were generated long-lived clones, which phenotype was assessed by FACS and immunocytochemistry. RESULTS: Our results showed that cultured primary trophoblasts have the EVT phenotype (Vim+/CK7+/HLA-C+/HLA-G+), like Sw71 cells. In both 3D culture settings, we obtained stable, round-shaped, multilayered spheroids. Although constructed from the same number of cells, the primary trophoblast spheroids were smaller. The primary trophoblast spheroids migrate successfully, and in term of invasion are equally potent but less stable as compared to Sw71 spheroids. CONCLUSIONS: The Sw71 cell line and cultured native trophoblast cells are interchangeable regarding their EVT phenotype (HLA-C+/HLA-G+/Vim+/CK7+). The blastocyst-like spheroids sourced by both types of cells differentiate in the same time frame and function similarly. We strongly advise the use of Sw71 spheroids as blastocyst surrogate for observation on trophectoderm differentiation and function during early human implantation.

HLA-Ehigh /HLA-Ghigh /HLA-IIlow Human iPSC-Derived Cardiomyocytes Exhibit Low Immunogenicity for Heart Regeneration.

Although human pluripotent stem cells (hPSCs)-derived cardiomyocytes (hPSC-CMs) can remuscularize infarcted hearts and restore post-infarct cardiac function, post-transplant rejection resulting from human leukocyte antigen (HLA) mismatching is an enormous obstacle. It is crucial to identify hypoimmunogenic hPSCs for allogeneic cell therapy. This study is conducted to demonstrate the immune privilege of HLA-Ehigh /HLA-Ghigh /HLA-IIlow human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs). Ischemia-reperfusion surgery is done to create transmural myocardial infarction in rats. At post-infarct 4 days, hPSC-CMs (1.0×107 cells per kg), including human embryonic stem cell-derived cardiomyocytes (hESC-CMs), HLA-Elow/HLA-Glow/HLA-IIhigh hiPSC-CMs, and HLA-Ehigh /HLA-Ghigh /HLA-IIlow hiPSC-CMs, are injected into the infarcted myocardium. Under the treatment of very low dose cyclosporine A (CsA), only HLA-Ehigh /HLA-Ghigh /HLA-IIlow hiPSC-CMs survive in vivo and improved post-infarct cardiac function with infarct size reduction. HLA-Ehigh /HLA-Ghigh /HLA-IIlow hiPSC-CMs activate the SHP-1 signaling pathway of natural killer (NK) cells and cytotoxic T cells to evade attack by NK cells and cytotoxic T cells. Herein, it is demonstrated that using a clinically relevant CsA dose, HLA-Ehigh /HLA-Ghigh /HLA-IIlow hiPSC-CMs repair the infarcted myocardium and restore the post-infarct heart function. HLA-Ehigh /HLA-Ghigh /HLA-IIlow hiPSCs are less immunogenic and may serve as platforms for regeneration medicine.

The Upregulation of HLA-G1 and miRNA-34a in Lens Epithelial Cells of Diabetic Retinopathy Patients.

Background: Retinopathy of diabetes is a chronic diabetes mellitus complication affecting retinal vessels, and some ocular complications' molecular mechanisms remain obscure. Objective: To evaluate the expression of HLA-G1, HLA-G5, miRNA-181a, and miRNA-34a in the lens epithelial cells of patients with retinopathy of diabetes. Methods: In a case-control study, 30 diabetic patients with retinopathy, 30 diabetic patients without retinopathy, and 30 cataract patients without diabetes mellitus as the control group were enrolled after a full description with details about the study methods and objectives. The expression of HLA G1, HLA G5, miRNA-181a, and miRNA-34a in lens epithelial cells was assessed by quantitative RT PCR. Moreover, the levels of HLA-G protein in aqueous humor were evaluated by the ELISA method. Results: HLA-G1 expression was significantly upregulated in the retinopathy group (P=0.003). The aqueous humor of diabetic retinopathy patients contained significantly higher levels of HLA-G protein compared with the non-diabetic patients (P=0.001). miRNA-181a was significantly downregulated in the diabetic retinopathy group compared with the patients without diabetes (P=0.001). In addition, miRNA-34a was upregulated in the retinopathy group (P=0.009). Conclusion: Taken together, the present results showed that HLA-G1 and miRNA-34a can be valuable markers for diabetic retinopathy. Our data offers new perspectives for improving the control of inflammation in the lens epithelial cells by considering HLA-G and miRNA.

Application of a JEG-3 organoid model to study HLA-G function in the trophoblast.

The human placenta is a unique temporary organ with a mysterious immune tolerance. The formation of trophoblast organoids has advanced the study of placental development. HLA-G is uniquely expressed in the extravillous trophoblast (EVT) and has been linked to placental disorders. With older experimental methodologies, the role of HLA-G in trophoblast function beyond immunomodulation is still contested, as is its role during trophoblast differentiation. Organoid models incorporating CRISPR/Cas9 technology were used to examine the role of HLA-G in trophoblast function and differentiation. JEG-3 trophoblast organoids (JEG-3-ORGs) were established that highly expressed trophoblast representative markers and had the capacity to differentiate into EVT. CRISPR/Cas9 based on HLA-G knockout (KO) significantly altered the trophoblast immunomodulatory effect on the cytotoxicity of natural killer cells, as well as the trophoblast regulatory effect on HUVEC angiogenesis, but had no effect on the proliferation and invasion of JEG-3 cells and the formation of TB-ORGs. RNA-sequencing analysis further demonstrated that JEG-3 KO cells followed similar biological pathways as their wild-type counterparts during the formation of TB-ORGs. In addition, neither HLA-G KO nor the exogenous addition of HLA-G protein during EVT differentiation from JEG-3-ORGs altered the temporal expression of the known EVT marker genes. Based on the JEG-3 KO (disruption of exons 2 and 3) cell line and the TB-ORGs model, it was determined that HLA-G has a negligible effect on trophoblast invasion and differentiation. Despite this, JEG-3-ORG remains a valuable model for studying trophoblast differentiation.

BiTE-Secreting CAR-γδT as a Dual Targeting Strategy for the Treatment of Solid Tumors.

HLA-G is considered as an immune checkpoint protein and a tumor-associated antigen. In the previous work, it is reported that CAR-NK targeting of HLA-G can be used to treat certain solid tumors. However, the frequent co-expression of PD-L1 and HLA-G) and up-regulation of PD-L1 after adoptive immunotherapy may decrease the effectiveness of HLA-G-CAR. Therefore, simultaneous targeting of HLA-G and PD-L1 by multi-specific CAR could represent an appropriate solution. Furthermore, gamma-delta T (γδT) cells exhibit MHC-independent cytotoxicity against tumor cells and possess allogeneic potential. The utilization of nanobodies offers flexibility for CAR engineering and the ability to recognize novel epitopes. In this study, Vδ2 γδT cells are used as effector cells and electroporated with an mRNA-driven, nanobody-based HLA-G-CAR with a secreted PD-L1/CD3ε Bispecific T-cell engager (BiTE) construct (Nb-CAR.BiTE). Both in vivo and in vitro experiments reveal that the Nb-CAR.BiTE-γδT cells could effectively eliminate PD-L1 and/or HLA-G-positive solid tumors. The secreted PD-L1/CD3ε Nb-BiTE can not only redirect Nb-CAR-γδT but also recruit un-transduced bystander T cells against tumor cells expressing PD-L1, thereby enhancing the activity of Nb-CAR-γδT therapy. Furthermore, evidence is provided that Nb-CAR.BiTE redirectes γδT into tumor-implanted tissues and that the secreted Nb-BiTE is restricted to the tumor site without apparent toxicity.

A Microphysiological Device to Model the Choriodecidual Interface Immune Status during Pregnancy.

During human pregnancy the chorion (fetal) lines decidua (maternal) creating the feto-maternal interface. Despite their proximity, resident decidual immune cells remain quiescent during gestation and do not invade the chorion. Infection and infiltration of activated immune cells toward the chorion are often associated with preterm birth. However, the mechanisms that maintain choriodecidual immune homeostasis or compromise immune barrier functions remain unclear. To understand these processes, a two-chamber microphysiological system (MPS) was created to model the human choriodecidual immune interface under normal and infectious conditions in vitro. This MPS has outer (fetal chorion trophoblast cells) and inner chambers (maternal decidual + CD45+ cells [70:30 ratio]) connected by microchannels. Decidual cells were treated with LPS to mimic maternal infection, followed by immunostaining for HLA-DR and HLA-G, immune panel screening by imaging cytometry by time of flight, and immune regulatory factors IL-8 and IL-10, soluble HLA-G, and progesterone (ELISA). LPS induced a proinflammatory phenotype in the decidua characterized by a decrease in HLA-DR and an increase in IL-8 compared with controls. LPS treatment increased the influx of immune cells into the chorion, indicative of chorionitis. Cytometry by time of flight characterized immune cells in both chambers as active NK cells and neutrophils, with a decrease in the abundance of nonproinflammatory cytokine-producing NK cells and T cells. Conversely, chorion cells increased progesterone and soluble HLA-G production while maintaining HLA-G expression. These results highlight the utility of MPS to model choriodecidual immune cell infiltration and determine the complex maternal-fetal crosstalk to regulate immune balance during infection.

Peripheral HLA-G/ILT-2 immune checkpoint axis in acute and convalescent COVID-19 patients.

The immunosuppressive non-classical human leukocyte antigen-G (HLA-G) can elicits pro-viral activities by down-modulating immune responses. We analysed soluble forms of HLA-G, IL-6 and IL-10 as well as on immune effector cell expression of HLA-G and its cognate ILT-2 receptor in peripheral blood obtained from hospitalised and convalescent COVID-19 patients. Compared with convalescents (N = 202), circulating soluble HLA-G levels (total and vesicular-bound molecules) were significantly increased in hospitalised patients (N = 93) irrespective of the disease severity. During COVID-19, IL-6 and IL-10 levels were also elevated. Regarding the immune checkpoint expression of HLA-G/ILT-2 on peripheral immune effector cells, the frequencies of membrane-bound HLA-G on CD3+ and CD14+ cells were almost identical in patients during and post COVID-19, while the frequency of ILT-2 receptor on CD3+ and CD14+ cells was increased during acute infection. A multi-parametric correlation analysis of soluble HLA-G forms with IL-6, IL-10, activation markers CD25 and CD154, HLA-G, and ILT-2 expression on immune cells revealed a strong positive correlation of soluble HLA-G forms with membrane-bound HLA-G molecules on CD3+/CD14+ cells only in convalescents. During COVID-19, only vesicular-bound HLA-G were positively correlated with the activation marker CD25 on T cells. Thus, our data suggest that the elevated levels of soluble HLA-G in COVID-19 are due to increased expression in organ tissues other than circulating immune effector cells. The concomitant increased expression of soluble HLA-G and ILT-2 receptor frequencies supports the concept that the immune checkpoint HLA-G/ILT-2 plays a role in the immune-pathogenesis of COVID-19.