Soluble human leukocyte antigen-G and interleukin-10 levels in plasma of psoriatic patients: preliminary study on a possible correlation between generalized immune status, treatments and disease

Cytokines in psoriasis: From pathogenesis to targeted therapy

Psoriasis is a multifactorial disease that affects 0.84% of the global population and it can be associated with disabling comorbidities. As patients present with thick scaly lesions, psoriasis was long believed to be a disorder of keratinocytes. Psoriasis is now understood to be the outcome of the interaction between immunological and environmental factors in individuals with genetic predisposition. While it was initially thought to be solely mediated by cytokines of type-1 immunity, namely interferon-γ, interleukin-2, and interleukin-12 because it responds very well to cyclosporine, a reversible IL-2 inhibitor; the discovery of Th-17 cells advanced the understanding of the disease and helped the development of biological therapy. This article aims to provide a comprehensive review of the role of cytokines in psoriasis, highlighting areas of controversy and identifying the connection between cytokine imbalance and disease manifestations. It also presents the approved targeted treatments for psoriasis and those currently under investigation.

Non-classical HLA class I molecules and their potential role in viral infections

Human Leukocyte Antigens (HLA) are classified in three different classes I, II and III, and represent the key mediators of immune responses, self-tolerance development and pathogen recognition. Among them, non-classical subtypes (HLA-Ib), e.g. HLA-E and HLA-G, are characterize by tolerogenic functions that are often exploited by viruses to evade the host immune responses. In this perspective, we will review the main current data referred to HLA-G and HLA-E and viral infections, as well as the impact on immune response. Data were selected following eligibility criteria accordingly to the reviewed topic. We used a set of electronic databases (Medline/PubMed, Scopus, Web of Sciences (WOS), Cochrane library) for a systematic search until November 2022 using MeSH keywords/terms (i.e. HLA, HLA-G, HLA-E, viral infection, SARS-CoV-2, etc.…). Recent studies support the involvement of non-classical molecules, such as HLA-E and HLA-G, in the control of viral infection. On one side, viruses exploit HLA-G and HLA-E molecule to control host immune activation. On the other side, the expression of these molecules might control the inflammatory condition generated by viral infections. Hence, this review has the aim to summarize the state of art of literature about the modulation of these non-classical HLA-I molecules, to provide a general overview of the new strategies of viral immune system regulation to counteract immune defenses.

The HLA-G Immune Checkpoint Plays a Pivotal Role in the Regulation of Immune Response in Autoimmune Diseases

The human G-leukocyte antigen (HLA-G) molecule is a non-classical major histocompatibility complex (MHC) class I molecule. The pertinence of HLA-G has been investigated in numerous studies which have sought to elucidate the relevance of HLA-G in pathologic conditions, such as autoimmune diseases, cancers, and hematologic malignancies. One of the main goals of the current research on HLA-G is to use this molecule in clinical practice, either in diagnostics or as a therapeutic target. Since HLA-G antigens are currently considered as immunomodulatory molecules that are involved in reducing inflammatory and immune responses, in this review, we decided to focus on this group of antigens as potential determinants of progression in autoimmune diseases. This article highlights what we consider as recent pivotal findings on the immunomodulatory function of HLA-G, not only to establish the role of HLA-G in the human body, but also to explain how these proteins mediate the immune response.

Analysis of key markers: IL-10/sHLA-G in psoriasis patients and the identification of 14-bp INDEL in the HLA-G gene

BACKGROUND

Psoriasis is a chronic inflammation resulting from interactions between immunological and genetic factors. An important tolerogenic role in this autoimmunological disease is played by HLA-G, which is modulated by IL-10. Therefore, this study (N.=80) aimed to evaluate changes in the serum sHLA-G and IL-10 levels in active psoriasis vulgaris and in the early stages of treatment with Methotrexate (MTX) compared to healthy controls. The 14-bp INDEL of the HLA-G gene was evaluated to find possible associations with clinical and laboratory variables.

METHODS

The level of sHLA-G and IL-10 in serum was evaluated (ELISA tests) in patients before the first dose of MTX and at week 12 of treatment, compared to healthy control donors. The 14-bp INDEL in 3'UTR of the HLA-G gene was identified using gDNA templates isolated from full blood. HLA-G amplicons were obtained by PCR, separated by electrophoresis and sequenced.

RESULTS

The mean serum IL-10 level was 4.653±3.33 pg/mL in psoriatic patients, 13.3±9.64 pg/mL after short MTX treatment, compared to 6.23 pg/mL in healthy controls. In addition, the serum level of sHLA-G was 0.275±0.03 ng/mL and 0.332±0.06 ng/mL in patients before and after MTX treatment, respectively, and 0.302±0.08 ng/mL in the control group. A correlation was found (r=-0.43; P<0.005) between the IL-10 and BSA serum levels in psoriasis patients after MTX treatment, indicating health improvement. The three genotypes identified in the 3'UTR of the HLA-G revealed no association with sHLA-G level in serum.

CONCLUSIONS

The mean levels of sHLA-G and the key anti-inflammatory cytokine IL-10 in the blood of pretreatment psoriasis patients are low and indicate that the immunotolerance mechanisms have failed. Treatment of psoriasis patients with low systemic levels of sHLA-G and IL-10 brings them to the same or higher protein levels, respectively, as in healthy donors. Higher sHLA-G levels in healthy donors and after MTX treatment, compared to the sHLA-G levels in the acute phase of psoriasis, indicates its immune system surveillance function.

Human leukocyte antigen-G donor-recipient matching of the 14-base pair polymorphism protects against cancer after heart transplant

BACKGROUND

After a transplant, cancer is a leading cause of morbidity and mortality. Human leukocyte antigen-G (HLA-G)-an immune checkpoint molecule-reduces allograft rejection by dampening host immune responses. Reports suggest malignant cells utilize HLA-G to evade the immune system and promote cancer development. Our objective was to evaluate HLA-G donor-recipient polymorphism matching and development of cancer after a heart transplant.

METHODS

Recipients (n = 251) and corresponding donors (n = 196) were genotyped retrospectively to identify HLA-G polymorphisms in the 5' regulatory (-725, -201), 3' untranslated (+3,197, +3,187, +3,142, 14-base pair insertion-deletion polymorphism [14-bp indel]) and coding regions (Haplotypes I-VI). Associations between donor-recipient polymorphism matching and development of cancer were assessed through multivariate proportional hazard regression models.

RESULTS

Recipient and donor (48.2 ± 12.1 and 35.5 ± 14.3 years, respectively) mean follow-up was 7.2 ± 4.6 years. Overall, 42 (16.7%) recipients developed de novo post-transplant cancer. 14-bp polymorphism matching significantly reduced the proportion of cancer, revealing an independent protective effect (hazard ratio [95% CI]: 0.26 [0.10-0.75]; p = 0.012). Recipients with the 14-bp insertion sequence, whether homozygous or heterozygous, had a lower proportion of cancer (p > 0.008), matching the INS sequence (INS/INS and INS/DEL) protected against cancer (p = 0.002). No differences were seen between matched vs unmatched cohorts regarding all donor-recipient pre-transplant and post-transplant characteristics. No other polymorphisms showed significant associations.

CONCLUSIONS

We investigated donor-recipient HLA-G polymorphism matching and development of cancer following a heart transplant. Donor-recipient 14-bp matching was an independent protective factor against cancer development. HLA-G may have a role in therapeutic and diagnostic strategies against cancer. Identifying relevant HLA-G polymorphisms may warrant alterations in immunotherapy to reduce post-transplant cancer risk.

Potential role of regulatory B cells in immunological diseases

Regulatory B cells (Bregs) are immune-modulating cells that affect the immune system by producing cytokines or cellular interactions. These cells have immunomodulatory effects on the immune system by cytokine production. The abnormalities in Bregs could be involved in various disorders such as autoimmunity, chronic infectious disease, malignancies, allergies, and primary immunodeficiencies are immune-related scenarios. Ongoing investigation could disclose the biology and the exact phenotype of these cells and also the assigned mechanisms of action of each subset, as a result, potential therapeutic strategies for treating immune-related anomalies. In this review, we collect the findings of human and mouse Bregs and the therapeutic efforts to change the pathogenicity of these cells in diverse disease.

Analysis of circulating soluble programmed death 1 (PD-1), neuropilin 1 (NRP-1) and human leukocyte antigen-G (HLA-G) in psoriatic patients

Introduction

Circulating soluble programmed death 1 (PD-1), neuropilin 1 (NRP-1) and human leukocyte antigen-G (HLA-G) take part in modulating immune tolerance causing disturbances in the molecular mechanisms responsible for maintenance of balance between effector and regulatory components of the immune system. Since their cell-surface expression levels were found to be changed in lesional and/or non-lesional skin of psoriatic patients, analysis of soluble PD-1, NRP-1 and HLA-G concentrations sheds more light on their role in detecting unbalanced immune tolerance in psoriasis.

Aim

To assess soluble PD-1, NRP-1 and HLA-G concentrations in psoriasis.

Material and methods

The study included 57 psoriatic patients and 29 controls. Duration of psoriasis was in the range 1 to 55 years; the median was 19 years. The plasma concentrations of soluble HLA-G (sHLA-G), soluble NRP-1 (sNRP-1) and soluble PD-1 (sPD-1) were examined using the ELISA method. Severity of the skin lesions was assessed by means of Psoriasis Area Severity Index (PASI), body surface area (BSA) and Physician Global Assessment (PGA).

Results

Psoriasis Area Severity Index in the studied group was in the range 3 to 43; the median was 12. Body surface area was in the range 2–75%; the median was 15%. The median value of PGA was 3. Soluble NRP concentration was significantly higher in the psoriatic patients (median: 1.59 pg/ml; range: 0.67–2.62 pg/ml) than in the control group (median: 1.35 pg/ml; range: 0.05–2.61 pg/ml) (p = 0.010). Soluble PD-1 and sHLA-G concentrations were not significantly different between the studied and control groups (p = 0.094 and p = 0.482, respectively).

Conclusions

Increased concentrations of sNRP-1 and unchanged values of sHLA-G and sPD-1 concentrations may be indicative of impaired immune tolerance mechanisms in psoriasis.

Variation at Interleukin-10 Locus Represents Susceptibility to Psoriasis in North Indian Population

BACKGROUND

IL-10 is an important pleiotropic, immunoregulatory and anti-inflammatory cytokine which plays a significant role in the pathogenesis of psoriasis.

OBJECTIVE

The aim of the present study was to determine whether the three polymorphic sites of the IL-10 gene, haplotype and serum level confer susceptibility to psoriasis.

METHOD

200 psoriatic patients and 200 controls were genotyped for three IL-10 polymorphic sites by ARMS polymerase chain reaction. Serum levels of IL -10 were measured by ELISA.

RESULTS

Our results demonstrated that polymorphism of IL-10 -592 C/A (adjusted* OR = 9.25; 95% CI =3.16- 27.06) and IL-10 1082 A/G (adjusted* OR = 4.28; (95% CI =1.46- 12.56) was found to be in association with increased risk of psoriasis while as IL- 10 819 C/T (adjusted* OR= 1.60; (95% CI = 0.65-3.95) polymorphism does not show any significant association with the risk of psoriasis. HT7 GTC haplotype is associated with increased risk of psoriasis. Serum levels of IL-10 were found to be significantly low in patients, as compared to controls with a non-significant correlation between serum IL-10 level and psoriasis severity.

CONCLUSION

IL-10 polymorphism imparted significant risk towards the development of psoriasis in North Indian population. Highlighting the role of IL-10 cytokine in the pathogenesis of psoriasis will help in the development of psoriasis management.

Stem Cells as Potential Candidates for Psoriasis Cell-Replacement Therapy

Recent years have seen considerable progress in explaining the mechanisms of the pathogenesis of psoriasis, with a significant role played in it by the hyper-reactivity of Th1 and Th17 cells, Treg function disorder, as well as complex relationships between immune cells, keratinocytes, and vascular endothelium. The effect of stem cells in the epidermis and stem cells on T cells has been identified and the dysfunction of various types of stem cells may be a prime cause of dysregulation of the inflammatory response in psoriasis. However, exploring these mechanisms in detail could provide a chance to develop new therapeutic strategies. In this paper, the authors reviewed data on the role played by stem cells in the pathogenesis of psoriasis and initial attempts at using them in treatment.

HLA-G gene 14-bp deletion variant protects Iranian subjects against chronic hepatitis B infection

To investigate whether 14-bp Ins/Del polymorphism in HLA-G gene is associated with the risk of chronic hepatitis B (CHB) infection. This study was performed on a total of 396 individuals including 199 CHB patients and 197 healthy subjects from a south-east Iranian population. We genotyped 14-bp Ins/Del polymorphism in the HLA-G gene using polymerase chain reaction method. The results of our study revealed that the HLA-G 14-bp deletion polymorphism was associated with a reduced risk of CHB at both allele and genotypic levels. The 14-bp Del allele and Ins/Del genotype were more frequent in control group than in CHB patients (37% vs 28% for Del allele with OR = 0.68 and p-value = .015; 73% vs 52% for Ins/Del genotype with OR = 0.43 and p-value = .001) and both were protective factors against CHB. However, no difference was found in the distribution of HLA-G 14-bp genotypes among subjects with varied levels of HBV DNA or hepatic enzymes (p > .05). Our findings, for the first time, suggest that the HLA-G 14-bp Ins/Del polymorphism may be a marker for genetic susceptibility to CHB infection.

Imiquimod-applied Interleukin-10 deficient mice better reflects severe and persistent psoriasis with systemic inflammatory state

Previous studies have shown that imiquimod-induced psoriasis-like skin inflammation in mice resembles phenotypic changes and cytokine profiles of human psoriasis. However, a psoriasis animal model reflecting the chronic inflammatory course and comorbidities has not yet been established. We aimed to evaluate the imiquimod-applied interleukin (IL)-10 deficient mouse model in comparison with previous models. IL-10 deficient and wild-type (WT) mice received either imiquimod or vehicle cream for 12 days and were sacrificed on day 15. For earlier time point data, either imiquimod or vehicle cream was applied for 2 days, and the mice were sacrificed on day 3. Imiquimod-applied IL-10 deficient mice showed more persistent psoriasis-like inflammation and higher severity index than did WT between day 8 and 15. Histopathologically, they demonstrated significantly thicker epidermis and larger number of CD45+, myeloperoxidase+ and IL-17+ cell counts on day 15. Quantitative reverse transcription-polymerase chain reaction with skin tissue revealed significantly higher imiquimod-induced IL-23p19 expression in imiquimod-applied IL-10 deficient mice on day 15. IL-10 deficient mice also showed significantly higher serum levels of imiquimod-induced IL-17A and tumor necrosis factor-α by enzyme-linked immunosorbent assay on day 15. Furthermore, IL-10 deficient mice showed more prominent increase of spleen weight and decrease of body weight in response to imiquimod application on day 3 and 15. In conclusion, IL-10 deficient mice model with imiquimod application may better reflect severe and persistent psoriasis with systemic inflammatory state.

The impact of IL10 polymorphisms and sHLA-G levels on the risk of schizophrenia

Early life immune aberrations have strongly been associated with the risk of schizophrenia. Amongst them, inflammation induced neurodevelopmental origin has emerged as one of the widely recognized underlying mechanisms. Interleukin-10 (IL-10) is an important anti-inflammatory and immunoregulatory cytokine. It modulates the expression of another immuno-inhibitory molecule, Human Leukocyte Antigen-G (HLA-G), predominantly expressed at the feto-maternal interface. Under physiological conditions, IL-10 and HLA-G molecules regulate the feto-maternal immune homeostasis by limiting the inflammatory states and influence the outcome of pregnancy. The aberrant expression of these molecules can cause pregnancy complications, which are known to confer strong risk to schizophrenia in the offspring. However, there is a considerable lack of information on the effect of the functional interactions between IL-10 and HLA-G on the risk of schizophrenia. We therefore examined the impact of possible correlation between IL-10 genetic variations and the plasma levels of soluble HLA-G (sHLA-G) on schizophrenia risk. Genotyping of IL10 (-592 C>A, -1082 A>G) single nucleotide polymorphisms (SNPs) was performed by PCR-RFLP method in 219 schizophrenia patients and 197 healthy subjects and levels of sHLA-G were estimated by ELISA in 46 patients and 44 healthy subjects. There was no significant difference in the genotype and allele frequencies between the groups for both the IL10 SNPs analyzed. However, we observed a correlation between IL10 genetic variation and plasma levels of sHLA-G in schizophrenia patients. Patients carrying CC genotype of IL10 -592C>A polymorphism had significantly lower sHLA-G levels compared to CA and AA genotypes. Our findings suggest the impact of possible correlation between IL-10 and HLA-G on schizophrenia risk.

HLA-G 14-bp polymorphism affects the age of onset in Type I Diabetes Mellitus

Type I diabetes mellitus (T1DM) is an organ-specific autoimmune disorder affecting the insulin-producing pancreatic cells. T1DM genetic association studies have so far revealed the involvement of more than 40 loci, with particularly strong associations for the human leucocyte antigens (HLA). Further to the well-established HLA class II associations, the immunomodulatory elements in the telomeric major histocompatibility complex locus, specifically nonclassical HLA class I, were also associated with T1DM, either in conferring susceptibility or by contributing to the overall pathogenesis. This study investigates the involvement of a 14-bp deletion polymorphism (rs371194629) at the 3' untranslated region of HLA-G in the context of T1DM and age of onset. The frequency of the polymorphism was determined in unrelated T1DM Cypriot patients and findings that emerge from this study show a strong association between the HLA-G 14-bp polymorphism and T1DM with respect to the age of onset. Specifically, the deletion/deletion (DEL/DEL) genotype was found to be associated with an early age of onset (P = 0.001), while the presence of the insertion allele (INS) was associated to a later age of onset (P = 0.0001), portraying a possible dominant effect over the deletion allele, a role in delaying disease onset and an overall involvement of HLA-G in the pathogenesis of type I diabetes mellitus.

HLA-G expression and regulation during Pseudomonas aeruginosa infection in cystic fibrosis patients

BACKGROUND

Deregulated immune response fails to control biofilm-forming bacteria, as Pseudomonas aeruginosa, in the lungs of cystic fibrosis (CF) patients. HLA-G is an immune-modulatory molecule involved in respiratory diseases and infections.

MATERIALS & METHODS

HLA-G mRNA and protein were analyzed in plasma and exhaled breath condensate from CF patients undergoing intravenous antibiotic treatment, CF cell line and murine model.

RESULTS

Therapy normalizes HLA-G plasmatic in CF patients suggesting a systemic anti-inflammatory role while in CF airway system, higher expression of HLA-G is associated with P. aeruginosa infection. CF cell line and murine model expressed higher HLA-G molecules in the presence of P. aeruginosa.

CONCLUSION

Plasmatic and lung HLA-G expression suggest a role in reducing systemic inflammation and supporting P. aeruginosa infection.

HLA-G Molecules in Autoimmune Diseases and Infections

Human leukocyte antigen (HLA)-G molecule, a non-classical HLA-Ib molecule, is less polymorphic when compared to classical HLA class I molecules. Human leukocyte antigen-G (HLA-G) was first detected on cytotrophoblast cells at the feto-maternal interface but its expression is prevalent during viral infections and several autoimmune diseases. HLA-G gene is characterized by polymorphisms at the 3' un-translated region and 5' upstream regulatory region that regulate its expression and are associated with autoimmune diseases and viral infection susceptibility, creating an unbalanced and pathologic environment. This review focuses on the role of HLA-G genetic polymorphisms, mRNA, and protein expression in autoimmune conditions and viral infections.

The emerging role of soluble HLA-G in the control of chemotaxis

HLA-G is an immunosuppressive molecule, that impairs the function of different immune cell populations, both in physiological and pathological conditions. Here, we have analyzed data obtained by our group and others regarding sHLA-G concentration in plasma from patients with different diseases. Next, we have summarized novel data regarding the impairment of chemotaxis of different immune effector cells mediated by sHLA-G. Finally, we have discussed the impact of this function on the immune response during cancer, viral infection, autoimmunity, and on B cell differentiation in secondary lymphoid organs. In conclusion, we have delineated a role of sHLA-G in the control of chemotaxis of immune effector cells, that may be relevant to modulate immune responses in different settings.

Immunological and histological evaluation of clinical samples from psoriasis patients treated with anti-CD6 itolizumab

Psoriasis is a chronic inflammatory disease with a prevalence of approximately 2-3% in the general population. The majority of diagnosed patients have plaque psoriasis, and about 20% have moderate-to-severe disease. Itolizumab, a new monoclonal antibody specific for the CD6 molecule mainly expressed on T lymphocytes, has demonstrated to inhibit in vitro ligand-induced proliferation and pro-inflammatory cytokine production. We assessed the immunological and histopathological effect of the antibody using clinical samples taken from 26 patients with moderate-to-severe psoriasis included in a clinical trial. The precursor frequency of lymphocytes activated with anti-CD2/CD3/CD28 beads, as well as the number of interferon (IFN)-γ-secreting T cells after stimulation, were measured at different time points of the study. Serum cytokine levels and anti-idiotypic antibody response to itolizumab were also evaluated. Additionally, lymphocyte infiltration and epidermis hyperplasia were studied in five patients. A significant reduction in T cell proliferation capacity and number of IFN-γ-producing T cells was found in treated patients. Serum levels of interleukin-6, tumor necrosis factor and IFN-γ showed an overall trend toward reduction. No anti-idiotypic antibody response was detected. A significant reduction in the epidermis hyperplasia was observed in analyzed patients. These results support the relevance of the CD6 molecule as a therapeutic target for the treatment of this disease.

Downregulation of immunoglobulin-like transcript-4 (ILT4) in patients with psoriatic arthritis

OBJECTIVE

The immunoglobulin-like transcript-4 (ILT4) is an inhibitory receptor that modulates the activity of innate immune agents. We determined the expression of ILT4 and analysed the relationship with the expression of costimulatory proteins and tumor necrosis factor-α (TNF-α) production in monocytes from patients with psoriatic arthritis (PsA) starting anti-TNF treatment.

METHODS

Peripheral blood monocytes from 15 healthy controls and from 16 patients with PsA were activated in vitro by CD40 ligand (CD40L) and analyzed for ILT4, CD40, CD80 and CD86 expression, and spontaneous lipopolysaccharide (LPS)-induced TNF-α production by flow cytometry, before and after treatment with adalimumab.

RESULTS

The percentage of ILT4-negative monocytes was greater in PsA patients compared to controls and negatively correlated with DAS44. Normal monocytes treated with sera of PsA patients showed a reduced expression of ILT4 compared with monocytes exposed to sera from controls. CD40, CD80 and CD86 expression was higher in patients compared to controls. Both spontaneous and LPS-induced TNF-α production was restricted to ILT4-negative monocytes and was greater in PsA patients compared to controls. Finally, twelve weeks-treatment with adalimumab resulted in a significant increase of ILT4 expression and a decrease of costimulatory molecules expression in PsA patients, compared to pre-therapy levels.

CONCLUSIONS

These data support the possibility that changes in the immunophenotype of monocytes play a role in the pathogenesis of PSA. Thus, modulation of the expression of ILT4 may represent an enticing new therapeutic target.

Markers of systemic inflammation in psoriasis: a systematic review and meta-analysis

Studies investigating systemic inflammation in psoriasis use different serum markers and report discrepant results. We set out to determine whether systemic inflammation is elevated in patients with psoriasis compared with healthy controls, and to measure the extent of this elevation, by summarizing available data on serum inflammatory markers. PubMed, Embase and Web of Science were searched from inception to March 2011. We included studies comparing the serum inflammatory markers interleukin (IL)-1β, IL-6, IL-10, C-reactive protein (CRP), intracellular adhesion molecule (ICAM)-1, E-selectin and tumour necrosis factor (TNF)-α in patients with psoriasis and healthy controls. Differences in serum marker levels between patients and controls were pooled as standardized mean differences (SMDs; Cohen's d) using a random-effects model. Seventy-eight studies were eligible. Of the 7852 individuals included, 3085 had (severe plaque) psoriasis. The pooled SMDs were higher in patients with psoriasis than in healthy controls for IL-6 [d = 1·32, 95% confidence interval (CI) 0·83-1·81], CRP (d = 1·83, 95% CI 0·76-2·90), TNF-α (d = 1·32, 95% CI 0·86-1·79), E-selectin (d = 1·78, 95% CI 1·32-2·25) and ICAM-1 (d = 1·77, 95% CI 1·15-2·39). The SMD between cases and controls for IL-1β and IL-10 was not significant. Age had a significant effect on the SMD for IL-6 and TNF-α. For IL-6 the effect size was higher for plaque psoriasis studies (d = 1·98). The effect size was not influenced by the Psoriasis Area and Severity Index, measurement method or quality assessment. The pooled analyses suggest modest but significantly elevated levels of the proinflammatory cytokines in the serum of patients with psoriasis with predominantly severe disease. To what extent this modest increment is clinically relevant could be investigated in a synthesis of all studies measuring inflammation before and after antipsoriatic therapy.

Matrix metalloproteinase-2 (MMP-2) generates soluble HLA-G1 by cell surface proteolytic shedding

Human leukocyte antigen-G (HLA-G) molecules are non-classical HLA class I antigens with an important role in pregnancy immune regulation and inflammation control. Soluble HLA-G proteins can be generated through two mechanisms: alternative splicing and proteolytic release, which is known to be metalloprotease mediated. Among this class of enzymes, matrix metalloproteinases (MMPs) might be involved in the HLA-G1 membrane cleavage. Of particular interest are MMP-2 and MMP-9, which regulate the inflammatory process by cytokine and chemokine modulation. We evaluated the effect of MMP-9 and MMP-2 on HLA-G1 membrane shedding. In particular, we analyzed the in vitro effect of these two gelatinases on the secretion of HLA-G1 via proteolytic cleavage in 221-G1-transfected cell line, in JEG3 cell line, and in peripheral blood mononuclear cells. The results obtained by both cell lines showed the role of MMP-2 in HLA-G1 shedding. On the contrary, MMP-9 was not involved in this process. In addition, we identified three possible highly specific cleavage sites for MMP-2, whereas none were detected for MMP-9. This study suggests an effective link between MMP-2 and HLA-G1 shedding, increasing our knowledge on the regulatory machinery beyond HLA-G regulation in physiological and pathological conditions.

Regulatory B cells suppress imiquimod-induced, psoriasis-like skin inflammation

Psoriasis is an inflammatory cutaneous disorder characterized by marked epidermal thickening and Th1 and Th17 cell infiltration. At present, the contribution of B cells to the pathogenesis of psoriasis is unclear. In mice, topical application of imiquimod induces inflamed skin lesions and serves as an experimental animal model for human psoriasis. In this study, we showed that imiquimod-induced skin inflammation was more severe in CD19(-/-) than WT mice. These inflammatory responses were negatively regulated by a unique IL-10-producing CD1d(hi)CD5(+) regulatory B cell subset (B10 cells) that was absent in CD19(-/-) mice and represented only 1-2% of splenic B220(+) cells in WT mice. Splenic B10 cells entered the circulation and migrated to draining LNs during imiquimod-induced skin inflammation, thereby suppressing IFN-γ and IL-17 production. Furthermore, adoptive transfer of these B10 cells from WT mice reduced inflammation in CD19(-/-) mice. The present findings provide direct evidence that B10 cells regulate imiquimod-induced skin inflammation and offer insights into regulatory B cell-based therapies for the treatment of psoriasis.

Maternal asthma and microRNA regulation of soluble HLA-G in the airway

BACKGROUND

We previously reported an interaction between maternal asthma and the child's HLA-G genotype on the child's subsequent risk for asthma. The implicated single nucleotide polymorphism at +3142 disrupted a target site for the microRNA (miR)-152 family. We hypothesized that the interaction effect might be mediated by these miRs.

OBJECTIVE

The objective of this study was to test this hypothesis in adults with asthma who are a subset of the same subjects who participated in our earlier family-based studies.

METHODS

We measured soluble HLA-G (sHLA-G) concentrations in bronchoalveolar lavage fluid (n = 36) and plasma (n = 57) from adult asthmatic subjects with and without a mother with asthma, and HLA-G and miR-152 family (miR-148a, miR-148b, and miR-152) transcript levels in airway epithelial cells from the same subjects.

RESULTS

miR-148b levels were significantly increased in airway epithelial cells from asthmatic subjects with an asthmatic mother compared with those seen in asthmatic subjects without an asthmatic mother, and +3142 genotypes were associated with sHLA-G concentrations in bronchoalveolar lavage fluid among asthmatic subjects with an asthmatic mother but not among those with a nonasthmatic mother. Neither effect was observed in the plasma (sHLA-G) or white blood cells (miRNA).

CONCLUSION

These combined results are consistent with +3142 allele-specific targeting of HLA-G by the miR-152 family and support our hypothesis that miRNA regulation of sHLA-G in the airway is influenced by both the asthma status of the subject's mother and the subject's genotype. Moreover, we demonstrate that the effects of maternal asthma on the gene regulatory landscape in the airways of the mother's children persist into adulthood.

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.

[New therapeutic targets in psoriatic arthritis]

Registries estimate that one third of patients with psoriatic arthritis (PsA) are "resistant" to of TNF-alpha blockers. Therefore, the search for new approaches to treatment of this disease may be justified. Currently the treatment options that have proven effective are associated with inhibition of the T cell costimulatory pathway (abatacept and alefacept) and blocking the P40 fraction of IL-12 and IL-23 (ustekinumab). A novel pathway inhibition, which deserves special attention is offered by apremilast. This molecule inhibits phosphodiesterase IV, responsible for hydrolyzing cyclic adenosine monophosphate to adenosine monophosphate, which causes an increase in cAMP. This metabolite is associated with decreased TNF-alpha. It has a modest efficacy (ACR 20 response of 43%), and subsequent studies have shown an improvement in visual analog scale and the SF36 compared to placebo. Currently there are five clinical trials in phase III to assess its effectiveness in parameters of inflammation and radiographic progression. The spectrum of possibilities before treatment failure with anti-TNF alpha, is augmented by the appearance of several reports that show efficacy with the individual use of CD20 inhibitors and IL-1. In patients with rheumatoid arthritis (RA) the effectiveness of molecules that inhibit signal transduction of cytokines (Anti-JAK) has been proven, so it is possible that in the future they may be used in patients with PsA.

Human leucocyte antigen-G: expression and function in airway allergic disease

Human leucocyte antigen-G (HLA-G) is a non-classical HLA class I molecule demonstrated originally in placental trophoblast cells. Recognition of the importance of HLA-G to the maternal immune accommodation of the semi-allogeneic fetus has led to investigations of its role in the suppression of immune responses and induction of tolerance. More recently, HLA-G has been shown to have increased expression in several immunological diseases including asthma and allergic rhinitis. The focus of this review is the potential role of HLA-G in immunological airway diseases.

Emerging topics and new perspectives on HLA-G

Following the Fifth International Conference on non-classical HLA-G antigens (HLA-G), held in Paris in July 2009, we selected some topics which focus on emerging aspects in the setting of HLA-G functions. In particular, HLA-G molecules could play a role in: (1) various inflammatory disorders, such as multiple sclerosis, intracerebral hemorrhage, gastrointestinal, skin and rheumatic diseases, and asthma, where they may act as immunoregulatory factors; (2) the mechanisms to escape immune surveillance utilized by several viruses, such as human cytomegalovirus, herpes simplex virus type 1, rabies virus, hepatitis C virus, influenza virus type A and human immunodeficiency virus 1 (HIV-1); and (3) cytokine/chemokine network and stem cell transplantation, since they seem to modulate cell migration by the downregulation of chemokine receptor expression and mesenchymal stem cell activity blocking of effector cell functions and the generation of regulatory T cells. However, the immunomodulatory circuits mediated by HLA-G proteins still remain to be clarified.

Expression of human leucocyte antigen-G primarily targets affected skin of patients with psoriasis

BACKGROUND

The nonclassical human leucocyte antigen (HLA)-G molecule has been well recognized as a tolerogenic molecule and few studies have evaluated the role of the molecule in inflammatory cutaneous autoimmune diseases.

OBJECTIVES

To evaluate the expression of HLA-G in skin specimens of patients with psoriasis and to analyse its correlation with epidemiological and clinical variables.

METHODS

Thirty untreated patients with psoriasis and 32 healthy individuals were enrolled. Immunohistochemistry was applied to identify HLA-G expression in formalin-fixed paraffin-embedded cutaneous skin biopsies.

RESULTS

Soluble and membrane-bound HLA-G expression was detected in 30 (90%) of the skin specimens from patients presenting clinical and histopathological features of psoriasis. Although infiltrating lymphomononuclear cells of the dermis exhibited HLA-G expression, the epidermis was primarily targeted. HLA-G expression was also observed in 27% (three of 11) of the specimens that exhibited no clinical and histopathological features of psoriasis (nonaffected areas). In contrast, skin specimens obtained from healthy individuals exhibited no HLA-G expression (P < 0·0001). The intensity of HLA-G expression was not associated with type I/II psoriasis, Psoriasis Area and Severity Index score or clinical forms.

CONCLUSIONS

As the HLA-G molecule was consistently expressed in affected and, to a lesser extent, in nonaffected areas of untreated patients with psoriasis, irrespective of the severity of the clinical variants, one may hypothesize that the presence of HLA-G may be responsible, at least in part, for the regulation of autoimmune effector cells.

HLA-G polymorphism influences the susceptibility to HCV infection in sickle cell disease patients

Despite its well known monogenic etiopathogenesis, sickle cell disease (SCD) is characterized by a striking variability of clinical presentation. There is growing evidence that genetic factors may be involved in this variability. Human leukocyte antigen (HLA)-G is a non-classical HLA molecule which was shown to be expressed at sites of inflammation and in inflammatory diseases. Besides its large and highly polymorphic promoter region, the 3' UTR region seems also to play an important role on regulating HLA-G expression. We investigated the influence of the 14 pb (rs1704) and the +3142 (rs1063320) HLA-G polymorphisms in 93 SCD patients in order to evaluate its potential role on clinical parameters. Twenty-one patients presented an HCV infection. Among all SCD patients 16 (22.2%) were homozygous for the +3142C genotype, none of them hepatitis C (HCV) positive. Controlling for blood transfusions in the last year, the C allele represented a dose dependent protection effect for HCV infection (PR = 0.41; 95% CI: 0.24-0.71). The +3142C allele was also underrepresented among patients with history of respiratory-tract infections. Our results support a role of the +3142 polymorphism in the susceptibility to infections, in particular to HCV infection, and suggest a possible interference of the HLA-G molecule in the response to infections, among SCD patients.

Blood levels of kynurenines, interleukin-23 and soluble human leucocyte antigen-G at different stages of Huntington's disease

There is substantial evidence that abnormal concentrations of oxidised tryptophan metabolites, produced via the kynurenine pathway, contribute to progressive neurodegeneration in Huntington's disease. We have now examined the blood levels of these metabolites in patients at different stages of Huntington's disease, assessed both in terms of clinical disease severity and numbers of CAG repeats. Close relatives of the patients were included in the study as well as unrelated healthy controls. Levels of lipid peroxidation products, the pro-inflammatory cytokine interleukin (IL)-23 and the soluble human leucocyte antigen-G (sHLA-G) were also measured. There were lower levels of tryptophan and a higher kynurenine : tryptophan ratio, indicating activation of indoleamine-2,3-dioxygenase, in the most severely affected group of patients, with increased levels of IL-23 and sHLA-G. Marked correlations were noted between IL-23 and the patient severity group, anthranilic acid levels and the number of CAG repeats, and between anthranilic acid and IL-23, supporting our previous evidence of a relationship between anthranilic acid and inflammatory status. Tryptophan was negatively correlated with symptom severity and number of CAG repeats, and positively correlated with sHLA-G. The results support the proposal that tryptophan metabolism along the kynurenine pathway in Huntington's disease is related to the degree of genetic abnormality, to clinical disease severity and to aspects of immunopathogenesis.

Human leukocyte antigen-G polymorphism in relation to expression, function, and disease

Human leukocyte antigen-G (HLA-G) is a nonclassical class Ib molecule belonging to the major histocompatibility complex. HLA-G appears to play a role in the suppression of immune responses and contribute to long-term immune escape or tolerance. The focus of this review is polymorphism in the HLA-G gene and protein and its possible importance in expression, function, and disease associations.