Single-nucleotide polymorphisms in 3'-untranslated region inducible costimulator gene and the important roles of miRNA in alopecia areata

Background

Alopecia areata (AA) spares the stem cell compartment and attacks only the base of the hair follicle, which is surrounded by infiltrating lymphocytes. AA is associated with polymorphisms in immune-related genes and with decreased function of CD4+CD25+ T regulatory (Treg) cells. Treg function is modulated by the costimulatory molecules, like inducible costimulator (ICOS) that are crucial in orienting T cell differentiation and function so that they strongly impact on the immunologic decision between tolerance or autoimmunity development.

Objective

The aim of our study was to investigate the possible association of AA with single-nucleotide polymorphisms (SNP) present in the ICOS 3'-untranslated region (3'UTR) region and to elucidate how SNPs modulate ICOS gene expression by affecting miRNA binding sites.

Methods

This is a case-control study performed in 184 patients with AA and 200 controls. ICOS gene and miRNA expression were analyzed by real-time polymerase chain reaction.

Results

The genotype carrying the rs4404254(C) [p = 0.012, OR (95% CI): 0.5 (0.3-0.8)] and rs4675379(C) [p = 0.015, OR (95% CI): 0.3 (0.1-0.8)] 3' UTR alleles was more frequently observed in AA patients than in controls and correlated with a reduced ICOS expression. miR-1276 significantly suppressed ICOS expression by binding to the 3'UTR of ICOS mRNA. Also, we observed that, miR-101 and miR-27b are upregulated, while miR-103 and miR-2355-3p are downregulated in peripheral blood mononuclear cells of AA patients compared to controls.

Conclusion

Our data show that rs4404254 and rs4675379 SNPs of ICOS gene are associated with AA and also reveal that the presence of rs4404254 polymorphism correlates with ICOS post-transcriptional repression by microRNA binding.

Increased frequency of interleukin-4 and reduced frequency of interferon-γ and IL-17-producing CD4+ and CD8+ cells in scleromyxedema

BACKGROUND

Little is known about the pathogenesis of scleromyxedema, a life-threatening fibromucinosis disease with immunological dysregulation.

OBJECTIVES

To investigate on T-cell phenotype, function and cytokine biology in search of new insights supporting the immunopathogenesis of the disease.

METHODS

We analysed the frequency of circulating lymphocyte subsets, the T-cell maturation stage, the generation of antigen-specific T-cell lines and T-cell cytokine secretion.

RESULTS

The analysis of T-cell maturation stage and the TCR spectratyping findings revealed that scleromyxedema patients showed clear immunological signs of long-lasting immune system activation and stimulation leading to a skewed T-cell repertoire. Moreover, these analyses showed that both CD4+ and CD8+ T cells from scleromyxedema patients have a profound deficiency (even after stimulation) relatively to the production of IFN-γ and IL17 with respect to healthy donor control cells, while they are massively skewed towards IL4 secretion after stimulation.

CONCLUSIONS

Our data indicate that a chronic Th2-skewed T-cell response against an unknown target antigen leading to abnormally high IL4 secretion, a pro-fibrotic cytokine, is a main immunological hallmark of scleromyxedema patients. These results, never reported before, may have a translational therapeutic value due to the availability of anti-IL4 agents such as dupilumab.

The role of AIRE polymorphisms in melanoma

Polymorphisms of AIRE, a transcription factor that up-regulates intrathymic expression of tissue-specific antigens including melanoma-associated antigens (MAAs), may variably affect the selection of MAAs-specific thymocytes, generating T-cell repertoires protecting or predisposing individuals to melanoma. We found that AIRE single nucleotide polymorphisms (SNPs) rs1055311, rs1800520 and rs1800522 were significantly more frequent in healthy subjects than in melanoma patients, independently from sex, age and stages of melanoma. The presence of these SNPs was associated with increased frequency of two T-cell clonotypes specific for MAGE-1 linking their protective effect to selection/expansion of MAA-specific T cells. Interestingly, mRNA transcribed on the rs1800520 SNP showed increased free energy than the wild type suggesting that its reduced stability may be responsible for the different activity of the polymorphic AIRE molecule. This finding may contribute at identifying subjects with increased risk of developing melanoma or patients with melanoma that may take benefit from immunotherapy.

Elispot and Elisa Assessment of Interferon-Gamma after Sublingual Immunotherapy

Allergic rhinitis (AR) is characterized by a Th2 polarized immune response, and specific immunotherapy modifies this arrangement, restoring a physiologic Th1 profile. Sublingual immunotherapy (SLIT) is widely prescribed. The aim of the study is to evaluate two different methods for assessing IFN-γ, namely ELISPOT and ELISA, before and after a pre-seasonal SLIT course as marker for Th1 response. Thirty-eight AR patients with pollen allergy assumed pre-seasonal SLIT for 3 months. Patients' blood samples for assessing IFN-γ serum levels were collected before initiating SLIT (baseline – T0), after 3 months pre-seasonal SLIT course (T1), and three months after completion of SLIT (T2). IFN-γ-specific producing cells, after allergen stimulation, were assessed by cytokine ELISPOT at the same time points. IFN-γ-specific producing cells significantly increased after SLIT both at T1 and T2 (p=0.0002). On the contrary, ELISA assessment did not reveal an increase in IFN-γ serum levels at any time point. In conclusion, these results demonstrate that ELISA assessment of serum IFN-γ is not suitable for identifying an early response.

Sublingual immunotherapy provides an early increase of interferon-gamma production

Allergic rhinitis (AR) is characterized by Th2 polarized immune response. Allergen-specific subcutaneous immunotherapy may restore a physiologic Th1 profile. However, there are few studies investigating the immunological effects of sublingual immunotherapy (SLIT). The aim of this study is to investigate whether a pre-seasonal SLIT course could affect IFN-gamma production. Forty-four AR patients with pollen allergy assumed pre-seasonal SLIT for 3 months. IFN-gamma-specific producing cells were assessed by cytokine ELISPOT before and 3 months after the beginning of SLIT. Visual analogue scale (VAS) for symptoms and medication score was also evaluated. The frequency of IFN-gamma-specific producing cells significantly increased after SLIT (p<0.01), and this increase was significantly associated with improvement of both symptoms (p<0.001) and medication use (p<0.01). In conclusion, these results may be considered clinically relevant as SLIT treatment may induce a quick IFN- gamma response that is related to clinical improvement.

Patients with Allergic Rhinitis Show an Allergen-Specific Interferon-Gamma Defect

Allergic rhinitis (AR) is characterized by Th2 polarized immune response. Consequently, allergic patients have a defect in IFN-γ production. So far, however, all the experimental studies have investigated only the IFN-γ production induced by the causal allergen. The aim of this study is to investigate whether there is a difference in the in vitro IFN-γ production, using different allergens as stimuli, in patients presenting with rhinitis due to pollen allergy. Forty-one AR patients with pollen allergy were enrolled. IFN-γ-specific producing cells were stimulated with PHA, causal pollen, and House Dust Mite (HDM). IFN-γ production was assessed by cytokine ELISPOT. IFN-γ production of peripheral blood mononuclear cells (PBMC) stimulated by specific pollen was significantly lower than IFN-γ production of PBMC stimulated by HDM (p<0.001). IFN-γ production of PBMC stimulated by specific pollen was significantly lower than IFN-γ production of PBMC stimulated by PHA (p<0.001). Moreover, in the HDM-sensitized patients, there seems to be a trend for a different defect. The present study highlights that the defective IFN-γ production is allergen specific and that HDM sensitization may also affects this parameter.

Association of -318 C/T and +49 A/G cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphisms with a clinical subset of Italian patients with systemic sclerosis

Systemic sclerosis (SSc) is a complex and heterogeneous autoimmune disorder with a multi-factorial pathogenesis. Like other autoimmune disorders, the possible role of specific cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphisms in predisposing to SSc has been hypothesized, but it remains controversial. CTLA-4 promoter (-318C/T) and exon 1 (+49 A/G) polymorphisms have been analysed in 43 Italian females with SSc and in 93 unrelated matched healthy controls by a newly designed tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) method. No significant association has been found with either polymorphisms.Nevertheless, SSc patients without concomitant Hashimoto's thyroiditis (HT) were carrying both the -318T allele (P = 0.031) and the +49 G allele (P = 0.076) more frequently than SSc patients with HT [defined by positivity for anti-thyroperoxidase (TPO) and anti-thyroglobulin (TGA) autoantibodies] than controls. Haplotype analysis confirms this association (P = 0.028), and suggests the predominant role of the -318T, whereas that of the +49 G, if any, seems weak. Thus, in Italian SSc patients the CTLA-4 -318C/T promoter polymorphism appears to be associated with the susceptibility to develop SSc without thyroid involvement. Larger studies are needed to confirm these findings and to clarify whether the -318C/T polymorphism is the functional responsible or whether it reflects the presence of another linked genetic element in the same chromosomal region.

AIRE gene polymorphisms in systemic sclerosis associated with autoimmune thyroiditis

Mutations in the autoimmune regulator (AIRE) gene are responsible for autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). Systemic sclerosis (SSc) is a non-organ-specific autoimmune disease mainly characterized by cutaneous involvement, that is frequently associated with other autoimmune manifestations common to APECED. Nineteen SSc patients, 22 patients affected by SSc associated with autoimmune thyroiditis, and 100 healthy controls were analyzed. We identified 11 AIRE gene variants, one of which has never previously been described. Intronic polymorphism G11107A was significantly correlated to SSc/thyroiditis. Data show that variants of the AIRE gene might be correlated to different clinical manifestations in SSc patients.

Disruption of immunological tolerance: role of AIRE gene in autoimmunity

The mechanism underlying the generation of T and B autoreactive clones in autoimmune diseases is still unknown. Among genetic factors implicated in autoimmunity, Autoimmune Regulator gene (AIRE) is one of the candidates to better understand the complex scenario of autoimmune manifestations. AIRE mutations are responsible for the development of autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) with monogenic autosomal recessive inheritance; it has been shown that AIRE regulates the negative selection of autoreactive T cells clones, driving the transcription of tissue-specific antigens in thymic epithelial cells. In various autoimmune manifestations correlated or not to APECED, AIRE variants act in a semidominant manner, leading to a reduction in AIRE protein amount per cell, and consequently to a marked decrease in ectopic proteins expression in the thymus. The co-occurrence of autoimmune diseases in the same individual has prompted several studies aimed to recognize shared patho-physiological mechanisms; in this scenario small reductions in function could explain the predisposition to autoimmunity in AIRE-heterozygous carriers of missense mutations; further studies to investigate whether the AIRE gene is involved in determining these autoimmune manifestations should be carried out.

Non-antigen-specific CD8(+) T suppressor lymphocytes in diseases characterized by chronic immune responses and inflammation

Recent studies on regulatory lymphocytes demonstrate that CD8(+) T suppressor (Ts) cells may have great relevance in controlling immune system homeostasis and avoiding development of chronic inflammatory diseases. Among the three subpopulations of CD8(+) Ts cells so far recognized in humans, the type 2 (non-antigen-specific) cell is characterized by the capacity to inhibit both T cell proliferation and cytotoxic T lymphocyte activity through secretion of soluble factors. Previous work has shown the impairment of in vitro generation of type 2 CD8(+) Ts cells from the peripheral blood of relapsed patients with multiple sclerosis, systemic lupus erythematosus, or systemic sclerosis. Here, similar findings are demonstrated for patients with human immunodeficiency virus or chronic hepatitis C virus infection. Furthermore, the presence of type 2 CD8(+) Ts cells infiltrating diseased tissues in patients with autoimmune thyroiditis or cancer is shown. Collectively, these findings suggest that type 2 CD8(+) Ts cells may be involved in the control of pathologic chronic immune responses, contributing in some cases to the pathogenesis of the disease.