HLA-G gene editing in tumor cell lines as a novel alternative in cancer immunotherapy.

Cancer immunotherapies based mainly on the blockade of immune-checkpoint (IC) molecules by anti-IC antibodies offer new alternatives for treatment in oncological diseases. However, a considerable proportion of patients remain unresponsive to them. Hence, the development of novel clinical immunotherapeutic approaches and/or targets are crucial.W In this context, targeting the immune-checkpoint HLA-G/ILT2/ILT4 has caused great interest since it is abnormally expressed in several malignancies generating a tolerogenic microenvironment. Here, we used CRISPR/Cas9 gene editing to block the HLA-G expression in two tumor cell lines expressing HLA-G, including a renal cell carcinoma (RCC7) and a choriocarcinoma (JEG-3). Different sgRNA/Cas9 plasmids targeting HLA-G exon 1 and 2 were transfected in both cell lines. Downregulation of HLA-G was reached to different degrees, including complete silencing. Most importantly, HLA-G - cells triggered a higher in vitro response of immune cells with respect to HLA-G + wild type cells. Altogether, we demonstrated for the first time the HLA-G downregulation through gene editing. We propose this approach as a first step to develop novel clinical immunotherapeutic approaches in cancer.

Wound Healing by Allogeneic Transplantation of Specific Subpopulation From Human Umbilical Cord Mesenchymal Stem Cells.

In normal physiological conditions, restoration of a functional epidermal barrier is highly efficient; nevertheless, when it fails, one of the main consequences is a chronic ulcerative skin defect, one of the most frequently recognized complications of diabetes. Most of these chronic venous ulcers do not heal with conventional treatment, leading to the appearance of infections and complications in the patient. Treatments based on the use of autologous mesenchymal stem cells (MSC) have been successful; however, its implementation entails complications. The umbilical cord offers an unlimited source of adult MSC (ucMSC) from the Wharton's jelly tissue with the same relevant features for clinical applicability and avoiding difficulties. It has recently been characterized by one specific subpopulation derived from ucMSC, the differentiated mesenchymal cells (DMCs). This subpopulation expresses the human leukocyte antigen-G (HLA-G) molecule, a strong immunosuppressive checkpoint, and vascular endothelial growth factor (VEGF), the most potent angiogenic factor. Considering the importance of developing a more effective therapy for wound treatment, especially ulcerative skin lesions, we analyzed DMC safety, efficacy, and therapeutic potential. By immunohistochemistry, umbilical cords HLA-G and VEGF positive were selected. Flow cytometry revealed that 90% of the DMC subpopulation are HLA-G+, CD44+, CD73+, CD29+, CD105+, CD90+, and HLA-DR-. Reverse transcription-polymerase chain reaction revealed the expression of HLA-G in all of DMC subpopulations. Upon co-culture with the DMC, peripheral blood mononuclear cell proliferation was inhibited by 50%. In a xenograft transplantation assay, DMC improved wound healing with no signs of rejection of the transplanted cells in immunocompetent mice. This study confirms that HLA-G allows allogeneic cell transplantation, and VEGF is fundamental for the restoration of the failure in blood supply. DMC population has positive effects on wound healing by promoting local angiogenesis in skin lesions. DMC could play a very important role in regenerative medicine and could be a novel allogeneic cell-therapeutic tool for wound healing.

The immune-checkpoint HLA-G/ILT4 is involved in the regulation of VEGF expression in clear cell renal cell carcinoma.

BACKGROUND: Clear cell renal cell carcinoma (ccRCC), the most aggressive renal cancer, is characterized by early lymph node metastases and bad prognosis. Most therapies targeting advanced or metastatic ccRCC are based, as first-line treatment, on the administration of the vascular endothelial growth factor (VEGF) neutralizing antibody termed Bevacizumab. Despite proven benefits, the expected results were not obtained for the majority of patients. The possibility that an intricate interplay between angiogenesis and immune-checkpoints might exist lead us to evaluate tumor angiogenesis, by means of VEGF expression together with the immune checkpoint HLA-G/ILT4. METHODS: Tumor specimens were obtained from patients from two separate cohorts: One from "Evita Pueblo" Hospital from Berazategui, (Buenos Aires, Argentina) and the second includes patients surgically operated at the Urology Department of Saint-Louis Hospital (Paris, France) with a confirmed ccRCC diagnosis. Immunohistochemistry was performed with specific antibodies directed against HLA-G, VEGF-A, VEGF-C, D240, CD34, ILT4 and Ca-IX. In addition, gene expression levels were measured in a cell line derived from a ccRCC patient by semi-quantitative RT-PCR. RESULTS: Our results show that the highly vascularized tumors of ccRCC patients express high levels of VEGF and the immune-checkpoint HLA-G. In addition, ILT4, one of the HLA-G receptors, was detected on macrophages surrounding tumor cells, suggesting the generation of an immune-tolerant microenvironment that might favor tumorigenesis. Notably, RT-qPCR analysis provided the first evidence on the transcriptional relationship between HLA-G/ILT4 and the VEGF family. Namely, in the presence of HLA-G or ILT4, the levels of VEGF-A are diminished whereas those of VEGF-C are increased. CONCLUSIONS: In an effort to find new therapeutic molecules and fight against metastasis dissemination associated with the poor survival rates of ccRCC patients, these findings provide the rationale for co-targeting angiogenesis and the immune checkpoint HLA-G.

The genetic diversity within the 1.4 kb HLA-G 5' upstream regulatory region moderately impacts on cellular microenvironment responses.

The HLA-G 5'URR extending 1.4 kb from the ATG presents a unique set of regulatory elements among HLA genes. Several variable sites have been described that coincide with or are close to these elements, thus HLA-G 5'URR polymorphism might influence the HLA-G expression level. We cloned the ten most frequent HLA-G 5'URR haplotypes to evaluate their activity on a luciferase reporter gene in HLA-G+ cell lines (JEG-3/choriocarcinoma and FON+/melanoma). We also investigated associations between the plasma HLA-G (sHLA-G) levels and the HLA-G 5'URR variability in 157 healthy individuals. Cell lines were transfected with pGL3-Basic vector constructions containing HLA-G 5'URR sequences. The G010101a (in JEG-3) and G010101b (in FON+) haplotypes exhibited higher promoter activity, whereas the G010101d (in JEG-3) and G010102a (in FON+) haplotypes exhibited lower promoter activity. In the presence of HLA-G inducers (interferon-ß and progesterone) or repressors (cyclopamine) HLA-G promoter activity was modulated, but certain haplotypes exhibited differential responses. No strict association was observed between plasma sHLA-G levels and the 5'URR haplotypes or genotypes; however, the G010101b haplotype was underrepresented among HLA-G-negative plasmas. Therefore, the HLA-G 5'URR polymorphism may have an impact on the modulation of HLA-G gene expression, but alone provides a limited predictive value for sHLA-G levels in vivo.

HLA-G1 increases the radiosensitivity of human tumoral cells.

Different molecules regulate the response of tumoral tissues to ionizing radiation. The objective of this work was to determine if HLA-G1 expression modulates the radiosensitivity of human tumoral cell lines. To this end, human melanoma M8 and human erythroleukemia K562 cell lines, with their correspondent HLA-G1 negative and positive variants, were gamma irradiated and the survival frequency was determined by clonogenic assay. The survival fraction of HLA-G1 expressing cells was around 60% of HLA-G1 negative cells. The generation of acidic vesicular organelles was higher in HLA-G1 positive cells. Apoptosis levels showed statistically significant differences only in K562 cells, whereas the variation in G2/M cycle progression was only significant in M8 cells. In addition, irradiation diminished cell-surface HLA-G1 and increased soluble HLA-G1 levels. Soluble HLA-G1 has no influence on cell survival in any cell line. In summary, we could demonstrate that HLA-G1 confers higher radiosensitivity to HLA-G1 expressing cells.

Polymorphic sites at the 3' untranslated region of the HLA-G gene are associated with differential hla-g soluble levels in the Brazilian and French population.

HLA-G molecule has well-recognized tolerogenic properties, and the encoding gene shows lower frequency of polymorphism at the coding region but higher variability at regulatory 5' and 3' untranslated (3'UTR) regions. At least three 3'UTR polymorphic sites have been associated with HLA-G mRNA regulation, including the 14 base pair (14bp) Insertion/Deletion, +3142C-G and +3187A-G. We studied the association of polymorphic sites at 3'UTR (sequencing analysis, encompassing the 14bp Ins-Del/+3003T-C/+3010C-G/+3027C-A/+3035C-T/+3142C-G/+3187A-G/+3196C-G polymorphic sites) with plasma soluble HLA-G levels (sHLA-G, detected by ELISA) in 187 French and 153 Brazilian healthy individuals. Allele and genotype frequencies were closely similar in both populations; however, Brazilians showed a higher HLA-G 3'UTR haplotype diversity. Considering sHLA-G levels in both populations altogether, individuals presenting 14bp Del/Del showed higher levels compared to 14bpIns/Ins genotype (P <0.05); those presenting +3010C/G showed higher levels compared to the +3010C-C genotype (P< 0.05); those presenting +3027C-C showed higher levels than the +3027A-A genotype (P< 0.05); and those bearing +3035C-C showed higher levels compared to the +3035C-T (P < 0.01) and +3035T-T (P < 0.05) genotypes. The analyses of 3'UTR haplotypes showed that UTR-1 (DelTGCCCGC) was associated with higher expression of sHLA-G, whereas UTR-5 (InsTCCTGAC) and UTR-7 (InsTCATGAC) with lower expression and other UTRs (UTR-2/3/4/6) exhibited intermediate levels. Since the differential expression of HLA-G may be beneficial or harmful depending on the underlying condition, the identification of individuals genetically programmed to differentially express HLA-G may help on defining novel strategies to control the immune response against the underlying disorder.

Expression of nonclassical molecule human leukocyte antigen-G in oral lesions.

INTRODUCTION: Human leukocyte antigen (HLA)-G is a nonclassic class I molecule that acts as a modulator of immune responses, and the expression of these molecules in virus-infected cells has been associated with subversion of the immune response. OBJECTIVE: In this study, we performed a cross-sectional study, systematically comparing the expression of the HLA-G in benign, premalignant, and malignant oral lesions and correlating it with the presence of high-risk and low-risk human papillomavirus (HPV) types. SPECIMENS AND METHODS: Oral biopsies were collected from 51 patients and analyzed by immunohistochemistry using anti-HLA-G antibody. Human papillomavirus detection and typing from oral biopsies were obtained by polymerase chain reaction using GP5+/GP6+ and specific primers. RESULTS: The 51 biopsies were stratified into 3 groups according to lesion grade: oral benign lesions (oral hyperplasia and papilloma, n = 16), oral premalignant lesions (oral leukoplakia with dysplasia and lichen planus, n = 17), and malignant lesions (oral squamous cell carcinoma, n = 18). Human leukocyte antigen-G overexpression was mainly observed in benign and premalignant oral lesions but was not related to HPV infection (P > .05). On the other hand, HPV DNA was detected in 24 (47%) oral lesions, mainly in benign and premalignant lesions, with the most frequent type detected being high-risk HPV type. CONCLUSION: The HLA-G molecule was expressed in a significant number of benign oral lesions and was not correlated with HPV infection or oral cancer.

In silico analysis of microRNAS targeting the HLA-G 3' untranslated region alleles and haplotypes.

It has been reported that microRNAs (miRNA) may have allele-specific targeting for the 3' untranslated region (3' UTR) of the HLA-G locus. In a previous study, we reported 11 3'UTR haplotypes encompassing the 14-bp insertion/deletion polymorphism and seven SNPs (+3003 T/C, +3010 C/G, +3027 C/A, +3035 C/T, +3142 C/G, +3187 A/G, and +3196 C/G), of which only the +3142 C/G SNP has been reported to influence the binding of miRNAs. Using bioinformatics analyses, we identified putative miRNA-binding sites considering the haplotypes encompassing these eight polymorphic sites, and we ranked the lowest free energies that could potentially lead to an mRNA degradation or translational repression. When a specific haplotype or a particular SNP was associated with a miRNA-binding site, we defined a free energy difference of 4 kcal/mol between alleles to classify them energetically distant. The best results were obtained for the miR-513a-5p, miR-518c*, miR-1262 and miR-92a-1*, miR-92a-2*, miR-661, miR-1224-5p, and miR-433 miRNAs, all influencing one or more of the +3003, +3010, +3027, and +3035 SNPs. The miR-2110, miR-93, miR-508-5p, miR-331-5p, miR-616, miR-513b, and miR-589* miRNAs targeted the 14-bp fragment region, and miR-148a, miR-19a*, miR-152, mir-148b, and miR-218-2 also influenced the +3142 C/G polymorphism. These results suggest that these miRNAs might play a relevant role on the HLA-G expression pattern.

Ionizing radiation modulates the surface expression of human leukocyte antigen-G in a human melanoma cell line.

Human leukocyte antigen G (HLA-G) is a nonclassical HLA class I molecule involved in fetus protection from the maternal immune system, transplant tolerance, and viral and tumoral immune escape. Tumor-specific HLA-G expression has been described for a wide variety of malignancies, including melanomas. The aim of this study was to evaluate whether ionizing radiation (IR) could modulate the surface expression of HLA-G1 in a human melanoma cell line that expresses endogenously membrane-bound HLA-G1. For this purpose, cells were exposed to increasing doses of gamma-irradiation (0-20 Gy) and HLA-G1 levels at the plasma membrane were analyzed at different times postirradiation by flow cytometry. HLA-G total expression and the presence of the soluble form of HLA-G1 (sHLA-G1) in the culture medium of irradiated cells were also evaluated. IR was capable of downregulating cell surface and total HLA-G levels, with a concomitant increase of sHLA-G1 in the medium. These results could indicate that gamma-irradiation decreases HLA-G1 surface levels by enhancing the proteolytic cleavage of this molecule.

HLA-G polymorphisms in women with squamous intraepithelial lesions harboring human papillomavirus.

Human papillomavirus (HPV) infection is etiologically associated with low- (LSIL) and high-grade squamous intraepithelial lesions (HSIL) and with cervical cancer. The progression or regression of the lesions may depend, among other factors, on the host heritable immune response. Because human leukocyte antigen (HLA)-G molecules are involved in the modulation of innate and adaptive immune responses, and because no previous studies have evaluated HLA-G polymorphism in patients with SIL, we conducted a study to assess the association between HLA-G polymorphisms and cervical lesions harboring HPV infection. Cervico-vaginal scrapings and blood samples were collected from 125 women with SIL (68 LSIL and 57 HSIL) and from 94 healthy women without HPV infection and cytological abnormalities. HPV type and HLA-G polymorphisms in exons 2, 3 and 8 (14 bp insertion/deletion) were evaluated by PCR methodology, and digested with restriction endonucleases. The Genepop software and the EM and PHASE algorithms were used for statistical analysis. A significant protective association was observed between the presence of the G(*)0103 allele and SIL and between the G0101/G0104 genotype and HSIL in the group of patients compared to control. The presence of the G0104/+14 bp and G0104/-14 bp haplotypes conferred susceptibility to SIL compared to control. In addition, patients possessing the G0104/+14 bp haplotype and harboring HPV-16 and -18 co-infections were particularly associated with HSIL. These findings suggest that HLA-G polymorphisms may be associated with HPV infection and SIL, consequently representing a profile of predisposition to cervical cancer.

HLA-G expression in the skin of patients with systemic sclerosis.

OBJECTIVE: To determine HLA-G expression in skin biopsies from patients with systemic sclerosis (SSc), and its association with epidemiological, clinical, and laboratory variables and survival. METHODS: Paraffin-embedded skin biopsies obtained from 21 SSc patients (14 limited SSc, 7 diffuse SSc) and from 28 healthy controls were studied. HLA-G expression was evaluated by immunohistochemistry. RESULTS: HLA-G molecules were detected in 57% of skin biopsies from patients with SSc (9 from limited SSc, 3 from diffuse SSc), whereas no control sample expressed HLA-G (p=0.000004). In patients, HLA-G molecules were consistently observed within epidermal and some dermal cells. HLA-G expression was associated with a lower frequency of vascular cutaneous ulcers (p=0.0004), telangiectasias (p=0.008), and inflammatory polyarthralgia (p=0.02). After a 15-year followup, SSc patients who exhibited HLA-G survived longer than patients who did not. CONCLUSION: HLA-G is expressed in skin biopsies from patients with SSc, and this is associated with a better disease prognosis. This suggests a modulatory role of HLA-G in SSc, as observed in other skin disorders.

Classical and non-classical HLA molecules and p16(INK4a) expression in precursors lesions and invasive cervical cancer.

OBJECTIVES: Viruses and tumour cells may regulate the expression of HLA molecules on the cell surface to escape immune system surveillance. Absence of classical HLA class I molecules may impair the action of specific cytotoxic cells, whereas non-classical HLA class I molecules may regulate innate and adaptive immune cells. We assess here the possible associations between classical/non-classical class I HLA and p16(INK4a) molecule expression in cervical biopsies of women infected with HPV, stratified according to grade of the lesion and HPV type. STUDY DESIGN: Cervical biopsies (N=74) presenting cervical intraepithelial neoplasia grade 1 (CIN1) (n=31), CIN2-3 (n=19), and invasive cancer (n=14) were evaluated alongside 10 normal cervical specimens. RESULTS: HLA-A/B/C/G staining was observed in the early stages of HPV infection. A significant association was detected between HLA-A/B/C staining and HPV16/18 infection (OR=0.12, 95%CI: 0.0163-0.7899; p=0.04). HLA-E expression increased with the progression of the lesion (chi(2)-test for trend=4.01; p=0.05), and a significant association was found between HLA-E staining and HPV16/18 infection (OR=11.25, 95%CI: 2.324-54.465; p=0.003). Irrespective of the grade of the lesion, HLA-A/B/C staining and p16(INK4a) presented a good concordance (Kappa: 0.67). CONCLUSIONS: HLA-E overexpression seemed to be associated with invasive cancer and HPV16/18 infection.

Estudios inmunologicos en pacientes de lepra indeterminada / Immunology studies in patients of indeterminit leprosy

Se efectuó un estudio longitudinal de un grupo de pacientes de lepra indeterminada, realizando dos tandas de estudios inmunológicos (leprominorreacción y test de formación de rosetas E) y clínicos en 1973 y 1977 respectivamente. Se observó una diferencia significativa en los estudios de rosetas E, entre los pacientes lepromino-positivos y los lepromino negativos (p menor 0,01) en 1973, incrementándose la diferencia en 1977(p menor 0,001). Coincidentemente cos esto hube una relación entre la respuesta inmunológica y la evolución hacia formas clínicas polares de la enfermedad, pudiendo existir también una influencia en esta evolución de la presencia o no de tratamiento específico. El viraje de leprominorreaciones de pacientes con valores normales de rosetas E en 1973 habla de una mayor sensibilidad del test in vitro como pronóstico.

Linfocitos T formadores de rosetas (LFR) en pacientes de lepra incaracterística

Se estudió un total de 16 pacientes de lepra incaracterística mediante al test de formación de rosetas, y la intradermorreación a la lepromina. De los resultados obtenidos se observó una correlación entre la negatividad del test cutáneo y una depleción en la población linfocitaria T de los pacientes estudiados. Se concluye la posibilidad de que el estudio de las poblaciones linfocitarias mediante el test de formación de rosetas pueda servir como prognóstico de la evolución posterior del paciente incaracterístico.