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.

Association of reduced maternal sHLA-G5 isoform levels and elevated TNF-α/IL-4 cytokine ratio with Recurrent Pregnancy Loss: A study on South Indian women.

Inflammation is of critical importance in successful implantation during pregnancy. However, the establishment of maternal immune tolerance towards semi-allograft foetus is more exigent and is achieved predominantly by human leukocyte antigen-G (HLA-G) isoforms with a special emphasis on soluble HLA-G5 (sHLA-G5). Constant inflammation and lack of resolution by anti-inflammatory milieu, due to aberrant expression of critical immunoregulatory molecules such as sHLA-G5 and dysfunctional T helper cells 1 and 2 (Th1-Th2) cytokine shift, can lead to adverse pregnancy outcomes including recurrent pregnancy loss (RPL). Serum samples of 270 pregnant women (135 healthy parous and 135 with a history of RPL) were evaluated for the concentrations of sHLA-G5, interleukin-4 (IL-4) and tumour necrosis factor-alpha (TNF-α) using sandwich enzyme-linked immunosorbent assay (ELISA) and found elevated levels of sHLA-G5 and IL-4 in controls and higher TNF-α levels and TNF-α:IL-4 ratio in patients (P < .05). Stratified data analysis based on the time of sample collection, that is the first and second trimesters exhibited higher sHLA-G5 and IL-4 in both first and second trimesters in controls than patients, while they displayed lower levels concerning TNF-α and TNF-α:IL-4 ratio (P < .05). However, within patients and controls in the first or second trimesters, there was a significant variation concerning sHLA-G5 alone. Further, the outcome of pregnancies studied in the present investigation revealed a significant elevation in sHLA-G5 levels among women with successful pregnancies compared with women who experienced pregnancy loss, therefore, concluding the potential application of sHLA-G5 isoform as a marker in assisting improved pregnancy outcomes.

HLA-G 14 bp In/Del and +3142 C/G genotypes are differentially expressed between patients with grade IV gliomas and controls.

Aim: Human Leukocyte Antigen-G (HLA-G) is a non-classical class I molecule that is involved in maternal-fetal immunotolerance. In cancer, this molecule contributes to the tumor escape. The aim of this study was to evaluate the 14 bp In/Del and +3142 C > G polymorphisms of the HLA-G 3' UTR and its relation with plasma and tissue HLA-G expression in patients with grade IV (high-grade) and grade I/II (low-grade) gliomas and controls.Patients and methods: Peripheral blood and tumor biopsies were collected from 85 patients with gliomas and blood samples from 94 controls. Polymorphisms were analyzed from blood DNA. Soluble HLA-G (sHLA-G) was measured by ELISA in plasma of the subjects and the tissue expression by immunohistochemistry on patient's tissue.Results: Higher levels of sHLA-G were observed in grade IV gliomas patients than in controls (p < 0.0001). In grade IV patients, the heterozygous 14pb In/Del, +3142 C/G genotypes and Del/C*In/G haplotype were associated with higher sHLA-G levels (p < 0.0001) when compared with controls. GBM patients were stratified into high and low sHLA-G expression and an association was found between +3142 C allele and high sHLA-G plasmatic levels (p = 0.0095). Tissue HLA-G immunolabel was higher in high-grade than low-grade gliomas (p = 0.0033).Conclusion: This was the first study evaluating HLA-G 3' UTR polymorphisms and expression in patients with gliomas. The 14 bp In/Del and +3142 C/G genotypes and haplotypes showed high influence over sHLA-G expression, suggesting a heterozygous advantage in the tumor context and may contribute to a worse prognosis in glioma patients.

Association of HLA-G 3'UTR Polymorphisms with Soluble HLA-G Levels and Disease Activity in Patients with Rheumatoid Arthritis: A Case-Control Study.

Background: Human leukocyte antigen (HLA)-G antigens are inducible non-classical major histocompatibility complex class Ib molecules which play an important role in the regulation of inflammatory processes and immunomodulation in autoimmune diseases. There are controversial reports on the impact of HLA-G gene polymorphisms on rheumatoid arthritis (RA). This study aimed at examining the impact of 14 base pair (bp) ins/del (rs66554220) and +3142G>C (rs1063320) polymorphisms and correlating these with soluble HLA-G (sHLA-G) levels to understand the susceptibility to RA in our sample cohort.Methods: Genomic DNA from 140 RA patients and 125 healthy controls was isolated using the salting out method. The genotyping of two polymorphisms of HLA-G (+3142G>C and 14 bp ins/del) was done by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and PCR method, respectively. Levels of sHLA-G were estimated by ELISA and disease activity was calculated by disease activity score (DAS28-ESR).Results: The HLA-G +3142G>C polymorphism was found to be associated with a decreased risk of RA as attributed to recessive inheritance tested model results (OR = 0.4, 95%C.I. = 0.2-0.9, p = .0313*, GG + GC versus CC). Our finding did not support an association between HLA-G 14 bp ins/del variant and risk/protection of RA. The sHLA-G levels were significantly lower in +3142GG and +3142GC RA patients as compared to healthy controls.Conclusion: HLA-G +3142G>C gene polymorphism might decrease the risk of occurrence of RA in our sample cohort as +3142CC genotype is associated with increased sHLA-G levels.Abbreviations: HLA-G: human leukocyte antigen-G; RA: rheumatoid arthritis; MHC: major histocompatibility complex; UTR: untranslated region; URR: upstream regulatory region; SLE: systemic lupus erythematous; PCR-RFLP: polymerase chain reaction restriction fragment length polymorphism; sHLA-G: soluble HLA-G; bp: base pair; ACR/EULAR: American College of Rheumatology/European League against Rheumatism; RF: rheumatoid factor; Anti-CCP: anti-cyclic citrullinated peptide; DAS28-ESR: Disease Activity Score 28- Erythrocyte Sedimentation Rate; TJC: tender joint count; SJC: swollen joint count; ESR: erythrocyte sedimentation rate; PGA: patient global assessment; HTN: hypertension; DM: diabetes mellitus; TB: tuberculosis; IEC: Institute Ethics Committee; ELISA: enzyme linked immunosorbent assay; ROC: receiver operating characteristics; AUC: area under curve; SNP: single nucleotide polymorphism; MTX: methotrexate; DMARDs: disease modifying anti-rheumatic drugs; Treg: regulatory T cells; IL: interleukinUnits: soluble HLA-G: Units/mL {U/mL}.

Plasma levels of soluble HLA-G and cytokines in papillary thyroid carcinoma before and after thyroidectomy.

BACKGROUND: Increasing evidence shows that chronic inflammation plays an important role in thyroid tumorigenesis. Cytokines as central mediators in inflammatory microenvironment can present both pro-tumour and anti-tumour effects and cytokine release may be influenced by soluble HLA-G (sHLA-G), an immune checkpoint molecule whose expression can also be induced by certain cytokines. AIM: To understand the role of these soluble factors in papillary thyroid cancer (PTC). METHODS: We evaluated plasma levels of sHLA-G and of 13 cytokines using ELISA and flow cytometry, respectively, in PTC patients at two time points: pre- and post-thyroidectomy; and control subjects. RESULTS: Compared with controls, IL-6 levels were increased, while IL-1ß, IFN-α and TGF-ß1 levels were decreased in pre-thyroidectomy PTC patients. IFN-α and TGF-ß1 efficiently discriminated patients from controls and were associated with extrathyroidal extension and lymph node metastasis, respectively. In addition, TNF and IL-13 were associated with male gender, lymph node metastasis and Hashimoto thyroiditis, and sHLA-G with tumour invasion. Compared with pre-thyroidectomy, IL-4, IL-10, TNF, IFN-α and TGF-ß1 levels were increased in post-thyroidectomy. CONCLUSION: There are significant changes in the cytokine profile after surgical removal of the thyroid tumour, and IFN-α e TGF-ß1 showed to be promising cytokines for discriminating PTC patients from controls. We also found that different cytokines are associated with clinicohistopathological characteristics of PTC related to poor prognosis, suggesting that cytokines seem to play an important role in PTC development and management.

Tropheryma whipplei Increases Expression of Human Leukocyte Antigen-G on Monocytes to Reduce Tumor Necrosis Factor and Promote Bacterial Replication.

BACKGROUND & AIMS: Infection with Tropheryma whipplei has a range of effects-some patients can be chronic carriers without developing any symptoms, whereas others can develop systemic Whipple disease, characterized by a lack a protective inflammatory immune response. Alterations in HLA-G function have been associated with several diseases. We investigated the role of HLA-G during T whipplei infection. METHODS: Sera, total RNA, and genomic DNA were collected from peripheral blood from 22 patients with classic Whipple's disease, 19 patients with localized T whipplei infections, and 21 asymptomatic carriers. Levels of soluble HLA-G in sera were measured by enzyme-linked immuosorbent assay, and expressions of HLA-G and its isoforms were monitored by real-time polymerase chain reaction. HLA-G alleles were identified and compared with a population of voluntary bone marrow donors. Additionally, monocytes from healthy subjects were stimulated with T whipplei, and HLA-G expression was monitored by real-time polymerase chain reaction and flow cytometry. Bacterial replication was assessed by polymerase chain reaction in the presence of HLA-G or inhibitor of tumor necrosis factor (TNF) (etanercept). RESULTS: HLA-G mRNAs and levels of soluble HLA-G were significantly increased in sera from patients with chronic T whipplei infection compared with sera from asymptomatic carriers and control individuals. No specific HLA-G haplotypes were associated with disease or T whipplei infection. However, T whipplei infection of monocytes induced expression of HLA-G, which was associated with reduced secretion of TNF compared with noninfected monocytes. A neutralizing antibody against HLA-G increased TNF secretion by monocytes in response to T whipplei, and a TNF inhibitor promoted bacteria replication. CONCLUSIONS: Levels of HLA-G are increased in sera from patients with T whipplei tissue infections, associated with reduced production of TNF by monocytes. This might promote bacteria colonization in patients.

Prognostic value of tumor-stroma ratio combined with the immune status of tumors in invasive breast carcinoma.

PURPOSE: Complex interactions occur between cancer cells and cells in the tumor microenvironment. In this study, the prognostic value of the interplay between tumor-stroma ratio (TSR) and the immune status of tumors in breast cancer patients was evaluated. METHODS: A cohort of 574 breast cancer patients was analyzed. The percentage of tumor stroma was visually estimated on Hematoxylin and Eosin (H&E) stained histological tumor tissue sections. Immunohistochemical staining was performed for classical human leukocyte antigen (HLA) class I, HLA-E, HLA-G, markers for regulatory T (Treg) cells, natural killer (NK) cells and cytotoxic T-lymphocytes (CTLs). RESULTS: TSR (P < .001) and immune status of tumors (P < .001) were both statistically significant for recurrence free period (RFP) and both independent prognosticators (P < .001) in which tumors with a high stromal content behave more aggressively as well as tumors with a low immune status. Ten years RFP for patients with a stroma-low tumor and high immune status profile was 87% compared to 17% of patients with a stroma-high tumor combined with low immune status profile (P < .001). Classical HLA class I is the most prominent immune marker in the immune status profiles. CONCLUSIONS: Determination of TSR is a simple, fast and cheap method. The effect on RFP of TSR when combined with immune status of tumors or expression of classical HLA class I is even stronger. Both are promising for further prediction and achievement of tailored treatment for breast cancer patients.

Association between HLA-G 14bp Gene Polymorphism and Serum sHLA-G Protein Concentrations in Preeclamptic Patients and Normal Pregnant Women.

BACKGROUND: Preeclampsia (PE) is a multisystem syndrome that is a primary source of fetal-maternal morbidity and mortality. Human leukocyte antigen-G (HLA-G) is a nonclassical Major histocompatibility complex (MHC) class-Ib molecule expressed on the extravillous trophoblast and seems to have immunomodulatory functions during pregnancy. The purpose of our study was to investigate whether HLA-G may be a vital marker in the modulation of the pregnancy. METHODS: In this case-control study, a number of 150 healthy pregnant women and 150 patients with PE had been genotyped for the 14 base-pair (bp) insertion/deletion polymorphism in exon 8 of the HLA-G gene, and the serum level of soluble HLA-G (sHLA-G) protein was measured using the enzyme-linked immunosorbent assay. RESULTS: Data showed that the PE syndrome was not related to the HLA-G 14 bp genotype. But, the serum level of sHLA-G in PE patients was significantly lower than that in healthy pregnant women in the third trimester (11.74 and 24.48 U/ml, respectively, p < 0.001). However, no significant association was observed between the HLA-G 14 bp genotype and serum sHLA-G level. CONCLUSION: Our results demonstrate that measurement of sHLA-G protein level may be helpful as a primary diagnosis for the pathogenesis of PE. Overall, this study suggests that the association between HLA-G 14 bp polymorphism and serum sHLA-G level in different ethnic populations of PE should be taken into consideration.

Increased levels of soluble HLA-G molecules in Tunisian patients with chronic hepatitis B infection.

Hepatitis B virus (HBV) infection is a global health problem. The mechanisms of immune tolerance in HBV infection are still unclear. The host immune response plays a critical role in determining the outcome of HBV infection. Human leucocyte antigen-G (HLA-G) is involved in immunotolerogenic process and infectious diseases. This study aimed to explore the implication of soluble HLA-G (sHLA-G) and its isoforms in HBV infection. Total sHLA-G (including shedding HLA-G1 and HLA-G5) was analysed by ELISA in 95 chronic HBV patients, 83 spontaneously resolvers and 100 healthy controls (HC). To explore the presence of sHLA-G dimers, we performed an immunoprecipitation and a Western blot analysis on positive samples for sHLA-G in ELISA. The serum levels of sHLA-G were significantly increased in patients with chronic HBV patients compared to spontaneously resolvers and HC (P<.0001). Interestingly, we found an increased level of sHLA-G1 in chronic HBV patients than in spontaneously resolvers and HC (P<.001). In addition, the expression of HLA-G5 seems to be higher in the sera of chronic HBV patients than spontaneously resolvers (P=.026). The analysis of HLA-G dimers showed the presence of homodimers in 93% of chronic HBV patients, 67% in spontaneously resolvers and 60% in HC. These results provide evidence that sHLA-G may have a crucial role in the outcome of HBV infection and could be proposed as a biomarker for infection outcome. Based on its tolerogenic function, HLA-G might be considered as a new promising immunotherapeutic approach to treat the chronic infection with HBV.

Circulating and renal expression of HLA-G prevented chronic renal allograft dysfunction in Japanese recipients.

BACKGROUND: Although the risk of acute rejection has been studied in renal transplanted patients, there is little data about the long-term renal survival effects of non-classical human leukocyte antigen class I (HLA-G) in Japanese patients. METHOD: We investigated the changes in the estimated glomerular filtration rate (eGFR) for Japanese, and factors affecting the eGFR in 141 adult Japanese subjects whose allografts had survived for at least 1 year. Clinical background data, gender, HLA matching status, the total ischemic time, ABO incompatibility, immunosuppressive therapy, and the serum soluble(s) HLA-G5 level were examined. In addition, renal biopsy specimens from 32 cases, which were obtained before, or 2-4 weeks or one year after the transplant were also evaluated for HLA-G1/5 expression using monoclonal anti-HLA-G antibodies (clone 87G or 4H84). RESULTS: The rates of change per year in the median eGFR (ΔeGFR) and sHLA-G5 were -1.5 ml/min/1.73 m2/year and 11.8 ng/ml, respectively. A positive correlation was detected between the ΔeGFR and sHLA-G5 (r = 0.188, p = 0.025). In multivariate regression analysis, sHLA-G5 and HLA-matching were significant predictors of an improvement in eGFR (beta for sHLA-G: 0.374, p = 0.009; beta for mismatching: -1.135, p = 0.045). The renal tubular epithelial cells (TEC) in 11 cases showed a perinuclear HLA-G1/5 expression after renal transplantation. The renal HLA-G1/5-positive patients displayed much better ΔeGFR (p < 0.05). In conclusion, the sHLA-G5 level and HLA matching status are independent predictors of renal allograft function, as determined by the ΔeGFR, in Japanese patients. HLA-G1/5 was also detected on TEC in the patients with favorable renal function.

Increased plasma soluble human leukocyte antigen-G in persistent wheezy infants.

BACKGROUND: Human leukocyte antigen (HLA)-G is a non-classical major histocompatibility complex class I antigen characterized by limited polymorphism in its coding region, unique tissue expression pattern in physiologic conditions and immunomodulatory properties. Recently, the level of soluble (s)HLA-G was found to be higher in atopic asthma and allergic rhinitis, but this remains to be clarified in wheezy infants. The aim of the present study was therefore to investigate sHLA-G in wheezy infants. METHODS: The subjects consisted of infants with persistent wheezing and positive modified asthma predictive index (mAPI; n = 30; persistent group) and those with transient wheezing and negative mAPI (n = 17; transient group). sHLA-G was measured in plasma using enzyme-linked immunosorbent assay. Total immunoglobulin E (IgE) and eosinophil count were measured, and skin testing was performed with a battery of 13 antigens with appropriate positive and negative controls. RESULTS: sHLA-G was significantly higher in the persistent wheezing (positive mAPI) group compared with the transient wheezing (negative mAPI) group (P = 0.008). There was no significant difference in peripheral blood eosinophil count and total IgE between the groups. CONCLUSIONS: The increased sHLA-G in infants with persistent wheeze suggests that sHLA-G may be able to be used to distinguish persistent from transient wheeze. Further comprehensive studies are needed on this topic.

Low expression of soluble human leukocyte antigen G in early gestation and subsequent placenta-mediated complications of pregnancy.

AIM: Abnormal placentation is a common pathogenic mechanism of many placenta-mediated complications of late pregnancy, including pre-eclampsia, fetal growth restriction, stillbirth, and placental abruption. During successful placentation, the trophoblast (which is a semi-allograft) is not rejected by decidual immune cells because of maternal immune tolerance, mainly induced by human leukocyte antigen G (HLA-G). Deficient HLA-G expression seems to be associated with the development of complications of pregnancy. The aim of this study was to determine whether low soluble HLA-G (sHLA-G) levels in maternal blood at the beginning of pregnancy may be associated with subsequent placenta-mediated complications. METHODS: For this retrospective case-control study, 117 cases of placenta-mediated complications of pregnancy and 234 controls with uneventful pregnancy were selected. Plasma sHLA-G levels were measured at 11-13 weeks' gestation by the enzyme-linked immunosorbent assay method in blood samples previously obtained at first-trimester prenatal screening for chromosomal fetal abnormalities. RESULTS: Women who subsequently developed placenta-mediated complications had significantly lower sHLA-G levels at the beginning of pregnancy (median, 43.08 IU/mL) than controls (median, 49.10 IU/mL; P = 0.008). An sHLA-G level lower than 43.50 IU/mL at the end of the first trimester was associated with a twofold increased risk of developing a pregnancy complication (odds ratio, 1.82; 95% confidence interval, 1.22-2.73). The strongest association, although only moderately strong, was observed with severe pre-eclampsia (odds ratio, 2.66; 95% confidence interval, 1.08-6.56). CONCLUSION: Placenta-mediated complications of pregnancy may be associated with low sHLA-G levels in the first trimester, suggesting a potential role of sHLA-G in the early stages of placentation.

Recipient HLA-G +3142 CC Genotype and Concentrations of Soluble HLA-G Impact on Occurrence of CMV Infection after Living-Donor Kidney Transplantation.

The expression modulation of the immunosuppressive non-classical Human leukocyte antigen-G (HLA-G) molecule and its soluble isoforms is an immune evasion strategy being deployed by cytomegalovirus (CMV). The +3142 C>G single nucleotide polymorphism (SNP) located within the 3' untranslated region (3'UTR) is of crucial importance for the regulation of HLA-G expression. Therefore, we analyzed the influence of the +3142 C>G HLA-G SNP on the occurrence of CMV infection in a cohort of 178 living-donor kidney recipients and their 178 corresponding donors. In addition, soluble HLA-G (sHLA-G) levels were quantified before and after transplantation. The presence of the HLA-G +3142 CC genotype in recipients, but not donors of our cohort as along with elevated sHLA-G levels (≥ 6.1 ng/mL) were associated with higher susceptibility to CMV infection after transplantation. Our results provided evidence that i) HLA-G is implicated in the establishment of CMV after living-donor kidney transplantation and ii) recipient HLA-G +3142 CC genotype and sHLA-G concentration levels could represent important predictive risk markers for CMV infection.

Human Leukocyte Antigen-G: A Promising Prognostic Marker of Disease Progression to Improve the Control of Human African Trypanosomiasis.

BACKGROUND: Human African trypanosomiasis (HAT) caused by Trypanosoma brucei gambiense can be diagnosed in the early hemolymphatic stage (stage 1 [S1]) or meningoencephalitic stage (stage 2 [S2]). Importantly, individuals harbouring high and specific antibody responses to Tbg antigens but negative parasitology are also diagnosed in the field (seropositive [SERO]). Whereas some develop the disease in the months following their initial diagnosis (SERO/HAT), others remain parasitologically negative for long periods (SERO) and are apparently able to control infection. Human leucocyte antigen (HLA)-G, an immunosuppressive molecule, could play a critical role in this variability of progression between infection and disease. METHODS: Soluble HLA-G (sHLA-G) was measured in plasma for patients in the SERO (n = 65), SERO/HAT (n = 14), or HAT (n = 268) group and in cerebrospinal fluid for patients in S1 (n = 55), early S2 (n = 93), or late S2 (n = 110). Associations between these different statuses and the soluble level or genetic polymorphisms of HLA-G were explored. RESULTS: Plasma sHLA-G levels were significantly higher in HAT (P = 6 × 10-7) and SERO/HAT (P = .007) than SERO patients. No difference was observed between the SERO/HAT and HAT groups. Within the HAT group, specific haplotypes (HG010102 and HG0103) displayed increased frequencies in S1 (P = .013) and late S2 (P = .036), respectively. CONCLUSIONS: These results strongly suggest the involvement of HLA-G in HAT disease progression. Importantly, high plasma sHLA-G levels in SERO patients could be predictive of subsequent disease development and could represent a serological marker to help guide therapeutic decision making. Further studies are necessary to assess the predictive nature of HLA-G and to estimate both sensitivity and specificity.

Serum IgG against Simian Virus 40 antigens are hampered by high levels of sHLA-G in patients affected by inflammatory neurological diseases, as multiple sclerosis.

BACKGROUND: Many investigators detected the simian polyomavirus SV40 footprints in human brain tumors and neurologic diseases and recently it has been indicated that SV40 seems to be associated with multiple sclerosis (MS) disease. Interestingly, SV40 interacts with human leukocyte antigen (HLA) class I molecules for cell entry. HLA class I antigens, in particular non-classical HLA-G molecules, characterized by an immune-regulatory function, are involved in MS disease, and the levels of these molecules are modified according with the disease status. OBJECTIVE: We investigated in serum samples, from Italian patients affected by MS, other inflammatory diseases (OIND), non-inflammatory neurological diseases (NIND) and healthy subjects (HS), SV40-antibody and soluble sHLA-G and the association between SV40-prevalence and sHLA-G levels. METHODS: ELISA tests were used for SV40-antibodies detection and sHLA-G quantitation in serum samples. RESULTS: The presence of SV40 antibodies was observed in 6 % of patients affected by MS (N = 4/63), 10 % of OIND (N = 8/77) and 15 % of NIND (N = 9/59), which is suggestive of a lower prevalence in respect to HS (22 %, N = 18/83). MS patients are characterized by higher sHLA-G serum levels (13.9 ± 0.9 ng/ml; mean ± St. Error) in comparison with OIND (6.7 ± 0.8 ng/ml), NIND (2.9 ± 0.4 ng/ml) and HS (2.6 ± 0.7 ng/ml) subjects. Interestingly, we observed an inverse correlation between SV40 antibody prevalence and sHLA-G serum levels in MS patients. CONCLUSION: The data obtained showed a low prevalence of SV40 antibodies in MS patients. These results seems to be due to a generalized status of inability to counteract SV40 infection via antibody production. In particular, we hypothesize that SV40 immune-inhibitory direct effect and the presence of high levels of the immune-inhibitory HLA-G molecules could co-operate in impairing B lymphocyte activation towards SV40 specific peptides.

Correlation of serum sHLA-G levels with cyst stage in patients with cystic echinococcosis: is it an immune evasion strategy?

Patients with cystic echinococcosis (CE) can harbour cysts for years or even decades, apparently without effect of the immune system on the metacestode. Although several immune evasion mechanisms by echinococcal cysts have been described, it is unclear whether the human leucocyte antigen (HLA) system plays a role in the susceptibility or resistance to CE in humans. HLA-G molecules are known to exert a suppressive action on dendritic cells maturation and on natural killer (NK) cells functions, therefore hampering T-cell responses and NK cytolysis. HLA-G plays an important role in immune tolerance, is involved in foetus and in allotransplant tolerance, and may be involved in tumoral and viral immune evasion. In this study, we assessed the presence and levels of soluble HLA-G (sHLA-G) in patients with CE using a commercial ELISA kit to determine whether host's HLA-G may have a role in the course of human CE.

Outcomes of Interferon/Ribavirin Therapy in Patients with HCV Defined by Expression of Plasma Soluble Human Leukocyte Antigen-G but Not IL-37.

BACKGROUND Chronic hepatitis C virus (HCV) infection leads to life-threatening complications worldwide. Immunomodulation signals the response to virus clearance. The immune-suppressive molecule human leukocyte antigen-G (HLA-G) has been shown to function in inhibiting both innate and adaptive immune responses. The objective of this study was to investigate the expression of HLA-G and IL-37 in sustained virological response (SVR) and non-SVR HCV-positive patients before and after complete treatment with a combination of pegylated interferon (IFN) and ribavirin (RBV). MATERIAL AND METHODS Our study included 132 chronic hepatitis C patents who received combined therapy with IFN-a and RBV. Both SVR and non-SVR patients were included. The end-of-treatment response was defined as undetectable HCV RNA at week 48. Patients with end-of-treatment response were detected by HCV RNA at 24 weeks after therapy. The expression levels of HLA-G and IL-37 at the end and 24 weeks after treatment were detected by ELISA. RESULTS Plasma HLA-G and IL-37 were significantly increased in HCV-infected patients compared with healthy individuals before treatment. Furthermore, HLA-G in SVR patients was noticeably decreased after treatment, while HLA-G in non-SVR patients had no changes after treatment. Additionally, both in SVR and non-SVR patients, the expression of IL-37 was remarkably reduced compared with baseline after treatment. CONCLUSIONS These findings suggest that elevation of HLA-G and IL-37 in HCV may play an important role in response to combined therapy with IFN-a and RBV. Monitoring the expression of HLA-G during therapy could contribute to adjusting the treatment program of HCV-infected patients.

Determination of HLA-G Expression and Evaluation of Its Role as a Prognostic Factor in Chronic Lymphocytic Leukemia.

BACKGROUND: In recent years, the clinical and biological features governing the clinical course of chronic lymphocytic leukemia (CLL) have been most extensively studied. Human leukocyte antigen-G (HLA-G) allows tumor cells to escape from the antitumor effect of the immune system. Recent studies have shown that various tumor cells show an increased HLA-G expression. Data regarding HLA-G expression in CLL are limited and controversial. The aim of this work is to evaluate flow cytometry study of HLA-G expression on cell surface and assess its relationship with other prognostic factors (CD38, ZAP70, beta 2 microglobulin [ß2MG]) in patients with CLL. DESIGN AND METHODS: Forty-five newly diagnosed CLL cases. White blood cell count, lymphocyte absolute count, hemoglobin level, platelet count, serum lactate dehydrogenase activity, and serum ß2MG level were studied at admission. In each patient, morphologic diagnosis of B-CLL was confirmed by flow cytometry HLA-G, CD38 and ZAP70 expression levels were measured with four-color flow cytometry. RESULTS: HLA-G positivity ranged between 1% and 12% in CLL patients. A significant correlation was found with CD38, ZAP70, disease stage, and ß2MG (P < 0.001). The off-treatment follow-up period was longer in the HLA-G negative group (P < 0.022). CONCLUSIONS: In conclusion, we suggest that, in addition to other prognostic factors, surface HLA-G expression can be considered as an independent prognostic factor. However, our work should be confirmed by further prospective studies, a longer off-treatment follow-up period, and a standardized method.

Association between decreased plasma levels of soluble human leukocyte antigen-G and severe pre-eclampsia.

OBJECTIVE: The aim of this study was to investigate the levels of different isoforms of soluble human leukocyte antigen-G (sHLA-G) in maternal plasma during early and late pregnancy, and to investigate the expression of sHLA-G isoforms in women with early or late-onset severe preeclampsia. METHODS: This prospective, nested, case-control study was performed in 24 early-onset severe preeclamptic, 34 late-onset severe preeclamptic, and 74 uncomplicated pregnant women. Plasma levels of sHLA-G1/5 were measured using ELISA. RESULTS: Plasma sHLA-G1 levels in women with late-onset severe preeclampsia were markedly lower compared with normal controls (median: 0 vs. 1.22 ng/mL) at the first trimester, and plasma sHLA-G1 levels in women with early-onset severe preeclampsia were markedly lower compared with normal controls at the second (median: 0 vs. 1.24 ng/mL) and third (median: 0 vs. 1.34 ng/mL) trimesters. There was no difference between the late-onset and early-onset groups at three trimesters. As for sHLA-G5, there was no difference in concentrations among the three groups at any time point. However, compared with controls, more women with early- or late-onset severe preeclampsia had undetectable sHLA-G5 levels in the first (71.4% and 76.2% vs. 14.1%), second (75.0% and 73.3% vs. 19.0%), and third (100.0% and 70.4% vs. 14.8%, respectively) trimester (all P<0.05). sHLA-G1 levels in the first (odds ratio [OR]=0.254, 95% confidence interval [CI]=0.109-0.591, P=0.010), second (OR=0.315, 95% CI=0.158-0.627, P=0.001), and third (OR=0.170, 95% CI=0.054-0.533, P=0.002) trimester was a risk factor for severe preeclampsia. CONCLUSION: Severe preeclampsia was associated with low/undetectable maternal plasma levels of sHLA-G. Low sHLA-G1 levels might be a risk marker for severe preeclampsia.

Role of HLA-G as a predictive marker of low risk of chronic rejection in lung transplant recipients: a clinical prospective study.

Human leukocyte antigen G (HLA-G) expression is thought to be associated with a tolerance state following solid organ transplantation. In a lung transplant (LTx) recipient cohort, we assessed (1) the role of HLA-G expression as a predictor of graft acceptance, and (2) the relationship between (i) graft and peripheral HLA-G expression, (ii) HLA-G expression and humoral immunity and (iii) HLA-G expression and lung microenvironment. We prospectively enrolled 63 LTx recipients (median follow-up 3.26 years [min: 0.44-max: 5.03]). At 3 and 12 months post-LTx, we analyzed graft HLA-G expression by immunohistochemistry, plasma soluble HLA-G (sHLA-G) level by enzyme-linked immunosorbent assay, bronchoalveolar lavage fluid (BALF) levels of cytokines involved in chronic lung allograft dysfunction (CLAD) and anti-HLA antibodies (Abs) in serum. In a time-dependent Cox model, lung HLA-G expression had a protective effect on CLAD occurrence (hazard ratio: 0.13 [0.03-0.58]; p = 0.008). The same results were found when computing 3-month and 1-year conditional freedom from CLAD (p = 0.03 and 0.04, respectively [log-rank test]). Presence of anti-HLA Abs was inversely associated with graft HLA-G expression (p = 0.02). Increased BALF level of transforming growth factor-ß was associated with high plasma sHLA-G level (p = 0.02). In conclusion, early graft HLA-G expression in LTx recipients with a stable condition was associated with graft acceptance in the long term.