Differences in the soluble HLA-G blood serum concentration levels in patients with ovarian cancer and ovarian and deep endometriosis

The Antigen-Processing Pathway via Major Histocompatibility Complex I as a New Perspective in the Diagnosis and Treatment of Endometriosis

Endometriosis is a debilitating gynecological disease defined as the presence of endometrium-like epithelium and/or stroma outside the uterine cavity. The most commonly affected sites are the pelvic peritoneum, ovaries, uterosacral ligaments, and the rectovaginal septum. The aberrant tissue responds to hormonal stimulation, undergoing cyclical growth and shedding similar to appropriately located endometrial tissue in the uterus. Common symptoms of endometriosis are painful periods and ovulation, severe pelvic cramping, heavy bleeding, pain during sex, urination and bowel pain, bleeding, and pain between periods. Numerous theories have been proposed to explain the pathogenesis of endometriosis. Sampson's theory of retrograde menstruation is considered to be the most accepted. This theory assumes that endometriosis occurs due to the retrograde flow of endometrial cells through the fallopian tubes during menstruation. However, it has been shown that this process takes place in 90% of women, while endometriosis is diagnosed in only 10% of them. This means that there must be a mechanism that blocks the immune system from removing endometrial cells and interferes with its function, leading to implantation of the ectopic endometrium and the formation of lesions. In this review, we consider the contribution of components of the Major Histocompatibility Complex (MHC)-I-mediated antigen-processing pathway, such as the ERAP, TAP, LMP, LNPEP, and tapasin, to the susceptibility, onset, and severity of endometriosis. These elements can induce significant changes in MHC-I-bound peptidomes that may influence the response of immune cells to ectopic endometrial cells.

HLA-G/sHLA-G and HLA-G-Bearing Extracellular Vesicles in Cancers: Potential Role as Biomarkers

As a non-classic major histocompatibility complex (MHC) class I molecule, human leukocyte antigen G (HLA-G) is expressed in fetal-maternal interface and immunoprivileged site only in healthy condition, and in pathological conditions such as cancer, it can be de novo expressed. It is now widely accepted that HLA-G is a key molecule in the process of immune escape of cancer cells, which is ubiquitously expressed in the tumor environment. This raises the possibility that it may play an adverse role in tumor immunity. The expression level of HLA-G has been demonstrated to be highly correlated with clinical parameters in many tumors, and its potential significance in the diagnosis and prognosis of cancer has been postulated. However, because HLA-G itself has up to seven different subtypes, and for some subtypes, detected antibodies are few or absent, it is hard to evaluate the actual expression of HLA-G in tumors. In the present work, we described (a) the structure and three main forms of HLA-G, (b) summarized the mechanism of HLA-G in the immune escape of tumor cells, (c) discussed the potential role of HLA-G as a tumor marker, and reviewed (d) the methods for detecting and quantifying HLA-G.

Prognostic significance of high circulating sHLA-G in ovarian carcinoma

HLA-G is a non-classical major histocompatibility complex class Ib molecule. Its expression has been described in various cancer types, including ovarian cancer. HLA-G molecule has been implicated in immune escape and in progression of ovarian tumor cells. Our goal was to assess if total soluble (s)HLA-G molecules or HLA-G5 and sHLA-G1 isoforms could be considered as circulating ovarian tumor biomarkers, we measured the concentration of these molecules in ovarian carcinoma patients stratified according with their clinicopathological parameters. sHLA-G, sHLA-G1 and HLA-G5 concentrations were dosed in plasma samples by sandwich-ELISA. The sHLA-G dimerization was analyzed after immunoprecipitation and SDS-PAGE migration. Total sHLA-G and sHLA-G1 levels were significantly represented in plasma of ovarian carcinoma patients compared to healthy controls. sHLA-G1 isoform concentration was highly represented in ovarian carcinoma compared to HLA-G5 isoforms. Additionally, high sHLA-G molecules have been found in aged patients, as well as in patients with advanced stages, and those with metastatic lymph nodes and those with distant metastasis. Elsewhere, sHLA-G monomers were highly represented in ovarian carcinoma patients compared to controls. sHLA-G plasmatic protein was highly represented in ovarian carcinoma. In effect, HLA-G might be considered as a new checkpoint molecule that could be used to assess progression and recurrence of the disease, thus placing it as a potential biomarker for advanced and complicated ovarian carcinoma.

Immunologic factors involved in the malignant transformation of endometriosis to endometriosis-associated ovarian carcinoma

INTRODUCTION

Endometriosis is a risk factor for low-grade serous, clear cell, and endometroid ovarian carcinoma. In both endometriosis and ovarian carcinoma, immunological factors are associated with clinical outcome. Chronic inflammation in endometriosis may be linked to tumorigenesis, but exact processes contributing to endometriosis-associated ovarian carcinoma remain unknown. This review aims to describe potential immunological factors involved in the malignant transformation of endometriosis into ovarian carcinoma.

METHODS

PubMed and Embase were searched from inception up to October 2020 for studies comparing immunological processes in endometriosis and endometriosis-associated ovarian carcinoma.

RESULTS

Detailed analysis of immune components in the malignant transformation of endometriosis into endometriosis-associated ovarian carcinoma is lacking. Altered levels of chemokines and cytokines as IL-6, IL-8, IL-10, and TNF-α are reported and the function, number and polarization of NK cells, dendritic cells, and monocytes differ between endometriosis and associated ovarian carcinoma compared to healthy tissue. In addition, altered inflammasome and complement systems, indicate a role for the immune system in the carcinogenesis of endometriosis.

CONCLUSION

Chronic inflammation in endometriosis may potentially drive inflammation-induced carcinogenesis in endometriosis-associated ovarian carcinoma. Exact immunological pathways and cellular processes remain unknown and require more thorough investigation.

Importance of the plasma soluble HLA-G levels for prognostic stratification with traditional prognosticators in colorectal cancer

An increased peripheral soluble HLA-G (sHLA-G) expression has been observed in various malignancies while its prognostic significance was rather limited. In this study, the prognostic value of plasma sHLA-G in 178 colorectal cancer (CRC) patients was investigated. sHLA-G levels were analyzed by specific enzyme-linked immunosorbent assay. Data showed sHLA-G levels were significantly increased in CRC patients compared with normal controls (36.8 U/ml vs 25.4 U/ml, p = 0.009). sHLA-G in the died were obviously higher than that of alive CRC patients (46.8 U/ml vs 27.4 U/ml, p = 0.012). Patients with sHLA-G above median levels (≥ 36.8 U/ml, sHLA-Ghigh) had a significantly shorter survival time than those with sHLA-Glow (< 36.8 U/ml, p < 0.001), and sHLA-G could be an independent prognostic factor for CRC patients. With stratification of clinical parameters in survival by sHLA-Glow and sHLA-Ghigh, sHLA-G exhibited a significant predictive value for CRC patients of the female (p = 0.036), the elder (p = 0.009), advanced tumor burden (T3 + 4, p = 0.038), regional lymph node status (N0, p = 0.041), both metastasis status (M0, p = 0.014) and (M1, p=0.018), and clinical stage (I + II, p = 0.018), respectively. Summary, our data demonstrated for the first time that sHLA-G levels is an independent prognosis factor and improves the prognostic stratification offered by traditional prognosticators in CRC patients.

Serum and peritoneal fluid concentrations of soluble human leukocyte antigen, tumor necrosis factor alpha and interleukin 10 in patients with selected ovarian pathologies

Background

Although immune system plays a key role in the pathogenesis of both endometriosis and ovarian cancer, its function is different. Therefore, we hypothesized, that selected immune parameters can serve as diagnostic markers of these two conditions. The aim of this study was to compare serum and peritoneal fluid concentrations of sHLA-G, IL-10 and TNF-alpha in women with selected ovarian pathologies: benign serous cysts, endometrioma and malignant tumors. Clinical significance of using them for diagnostic purposes in women with serous ovarian cysts, endometriosis, and ovarian cancer, which in the future may improve the early diagnosis of ovarian diseases.

Case Presentation

The study included women treated surgically for benign serous ovarian cysts, ovarian endometrioma and serous ovarian adenocarcinomas. Peripheral blood and peritoneal fluid samples were obtained intraoperatively.

Patients with benign serous cysts, endometrioma and ovarian malignancies did not differ significantly in terms of their serum and peritoneal fluid concentrations of sHLA-G. Ovarian cancer patients presented with significantly higher median serum concentrations of IL-10 and TNF-alpha than other study subjects. Median concentrations of IL-10 and TNF-alpha in peritoneal fluid turned out to be the highest in ovarian cancer patients, followed by women with endometrioma and subjects with benign serous cysts. All these intergroup differences were statistically significant. Irrespective of the group, median concentrations of sHLA-G, IL-10 and TNF-alpha in peritoneal fluid were higher than serum levels of these markers.

Conclusions

Elevated serum and peritoneal fluid concentrations of IL-10 and TNF-alpha distinguish ovarian malignancies and endometriomas from benign serous ovarian cysts. In contrast to endometriosis, ovarian malignancies are characterized by elevated peritoneal fluid concentrations of IL-10 and TNF-alpha, elevated serum concentrations of IL-10 and low serum levels of TNF-alpha. Serum and peritoneal fluid concentrations of sHLA-G have no diagnostic value in differentiating between ovarian malignancies and endometriomas.

Immunomodulation of classical and non-classical HLA molecules by ionizing radiation

Radiotherapy has been employed for the treatment of oncological patients for nearly a century, and together with surgery and chemotherapy, radiation oncology constitutes one of the three pillars of cancer therapy. Ionizing radiation has complex effects on neoplastic cells and on tumor microenvironment: beyond its action as a direct cytotoxic agent, tumor irradiation triggers a series of alterations in tumoral cells, which includes the de novo synthesis of particular proteins and the up/down-regulation of cell surface molecules. Additionally, ionizing radiation may induce the release of "danger signals" which may, in turn lead to cellular and molecular responses by the immune system. This immunomodulatory action of ionizing radiation highlights the importance of the combined use (radiotherapy plus immunotherapy) for cancer healing. Major histocompatibility complex antigens (also called Human Leukocyte Antigens, HLA in humans) are one of those molecules whose expression is modulated after irradiation. This review summarizes the modulatory properties of ionizing radiation on the expression of HLA class I (classical and non-classical) and class II molecules, with special emphasis in non-classical HLA-I molecules.

HLA-dependent tumour development: a role for tumour associate macrophages?

HLA abnormalities on tumour cells for immune escape have been widely described. In addition, cellular components of the tumour microenvironment, in particular myeloid derived suppressor cells (MDSC) and alternatively activated M2 tumour-associated macrophages (TAMs), are involved in tumour promotion, progression, angiogenesis and suppression of anti-tumour immunity. However, the role of HLA in these activities is poorly understood. This review details MHC class I characteristics and describes MHC class I receptors functions. This analysis established the basis for a reflection about the crosstalk among the tumour cells, the TAMs and the cells mediating an immune response.The tumour cells and TAMs exploit MHC class I molecules to modulate the surrounding immune cells. HLA A, B, C and G molecules down-regulate the macrophage myeloid activation through the interaction with the inhibitory LILRB receptors. HLA A, B, C are able to engage inhibitory KIR receptors negatively regulating the Natural Killer and cytotoxic T lymphocytes function while HLA-G induces the secretion of pro-angiogenic cytokines and chemokine thanks to an activator KIR receptor expressed by a minority of peripheral NK cells. The open conformer of classical MHC-I is able to interact with LILRA receptors described as being associated to the Th2-type cytokine response, triggering a condition for the M2 like TAM polarization. In addition, HLA-E antigens on the surface of the TAMs bind the inhibitory receptor CD94/NKG2A expressed by a subset of NK cells and activated cytotoxic T lymphocytes protecting from the cytolysis.Furthermore MHC class II expression by antigen presenting cells is finely regulated by factors provided with immunological capacities. Tumour-associated macrophages show an epigenetically controlled down-regulation of the MHC class II expression induced by the decoy receptor DcR3, a member of the TNFR, which further enhances the M2-like polarization. BAT3, a positive regulator of MHC class II expression in normal macrophages, seems to be secreted by TAMs, consequently lacking its intracellular function, it looks like acting as an immunosuppressive factor.In conclusion HLA could cover a considerable role in tumour-development orchestrated by tumour-associated macrophages.

Ovarian cancer molecular pathology

Ovarian cancer (OVC) is the fourth leading cause of cancer mortality among women in Europe and the United States. Its early detection is difficult due to the lack of specificity of clinical symptoms. Unfortunately, late diagnosis is a major contributor to the poor survival rates for OVC, which can be attributed to the lack of specific sets of markers. Aside from patients sharing a strong family history of ovarian and breast cancer, including the BRCA1 and BRCA2 tumor suppressor genes mutations, the most used biomarker is the Cancer-antigen 125 (CA-125). CA-125 has a sensitivity of 80 % and a specificity of 97 % in epithelial cancer (stage III or IV). However, its sensitivity is 30 % in stage I cancer, as its increase is linked to several physiological phenomena and benign situations. CA-125 is particularly useful for at-risk population diagnosis and to assess response to treatment. It is clear that alone, CA-125 is inadequate as a biomarker for OVC diagnosis. There is an unmet need to identify additional biomarkers. Novel and more sensitive proteomic strategies such as MALDI mass spectrometry imaging studies are well suited to identify better markers for both diagnosis and prognosis. In the present review, we will focus on such proteomic strategies in regards to OVC signaling pathways, OVC development and escape from the immune response.

The immunosuppressive molecule HLA-G and its clinical implications

Human leukocyte antigen G (HLA-G) is a non-classical major histocompatibility complex (MHC) class I molecule that, through interaction with its receptors, exerts important tolerogenic functions. Its main physiological expression occurs in placenta where it seems to participate in the maternal tolerance toward the fetus. HLA-G has been studied as a marker of pregnancy complications such as abortion or pre-eclapmsia. Although HLA-G is not expressed in most adult tissues, its ectopic expression has been observed in some diseases such as viral infections, autoimmune disorders, and especially cancer. HLA-G neo-expression in cancer is associated with the capability of tumor cells to evade the immune control. In this review, we will summarize HLA-G biology and how it participates in these physiopathological processes. Special attention will be paid to its role as a diagnostic tool and also as a therapeutic target.

Human leukocyte antigen-G in cancer: are they clinically relevant?

The immunotolerant human leukocyte antigen (HLA)-G has direct inhibitory effects on natural killer cells (NK), dendritic cells (DC), T cells and can induce tolerant regulatory cells. The expression of HLA-G has been correlated with the tolerance of the fetus, the acceptance of organ transplants, and the immune escape of tumor cells and virus-infected cells. In the context of malignancies, aberrant induction of HLA-G expression has been extensively investigated and its clinical relevance has been postulated. We here focus on the HLA-G expression in malignancies and its relevance to tumor cell immune escaping and disease progression.