Transcription factor GATA-3 is involved in repression of promoter activity of the human interleukin-4 gene

Transcriptomic analysis and novel insights into lens fibre cell differentiation regulated by Gata3

Gata3 is a DNA-binding transcription factor involved in cellular differentiation in a variety of tissues including inner ear, hair follicle, kidney, mammary gland and T-cells. In a previous study in 2009, Maeda et al. (Dev. Dyn.238, 2280–2291; doi:10.1002/dvdy.22035) found that Gata3 mutants could be rescued from midgestational lethality by the expression of a Gata3 transgene in sympathoadrenal neuroendocrine cells. The rescued embryos clearly showed multiple defects in lens fibre cell differentiation. To determine whether these defects were truly due to the loss of Gata3 expression in the lens, we generated a lens-specific Gata3 loss-of-function model. Analogous to the previous findings, our Gata3 null embryos showed abnormal regulation of cell cycle exit during lens fibre cell differentiation, marked by reduction in the expression of the cyclin-dependent kinase inhibitors Cdkn1b/p27 and Cdkn1c/p57, and the retention of nuclei accompanied by downregulation of Dnase IIβ. Comparisons of transcriptomes between control and mutated lenses by RNA-Seq revealed dysregulation of lens-specific crystallin genes and intermediate filament protein Bfsp2. Both Cdkn1b/p27 and Cdkn1c/p57 loci are occupied in vivo by Gata3, as well as Prox1 and c-Jun, in lens chromatin. Collectively, our studies suggest that Gata3 regulates lens differentiation through the direct regulation of the Cdkn1b/p27and Cdkn1c/p57 expression, and the direct/or indirect transcriptional control of Bfsp2 and Dnase IIβ.

Paraquat reduces natural killer cell activity via metallothionein induction

Paraquat (PQ), one of the most widely used herbicides, has been used for several decades in agriculture. Some studies suggest that PQ has effects on the immune system. Moreover, previous studies have shown that PQ imparted some immunosuppressive effects. In the present study, cytotoxicity assays using splenic NK cells from mice treated for 28 days with PQ (at 0.2, 1, and 5 mg/kg) were performed to determine whether PQ altered the function of NK cells. Given that PQ was expected to induce an immunosuppressive effect, it was hypothesized that a gene involved in cellular metal ion homeostasis, metallothionein-1 (MT-1), could play an important role in this outcome. This belief was based on the fact that MT1 encodes a protein responsible for zinc ion homeostasis, and that a reduction in free zinc ion levels impairs NK cell function. The results showed that PQ treatments led to increased MT expression in several organs (liver, kidneys, testes) and in splenocytes, caused a reduction of both free zinc ions in sera and in free intracellular zinc, and reduced the expression of GATA-3, a zinc-finger transcription factor important for maturation and activity of T-cells and NK cells. These results provide a basis for a new molecular mechanism to describe potential immunosuppressive effects of PQ in vivo.

Generation of a novel regulatory NK cell subset from peripheral blood CD34+ progenitors promoted by membrane-bound IL-15

BACKGROUND

NK cells have been long time considered as cytotoxic lymphocytes competent in killing virus-infected cells and tumors. However, NK cells may also play essential immuno-regulatory functions. In this context, the real existence of a defined NK subset with negative regulatory properties has been hypothesized but never clearly demonstrated.

METHODOLOGY/PRINCIPAL FINDINGS

Herein, we show the in vitro generation from human peripheral blood haematopoietic progenitors (PB-HP), of a novel subset of non-cytolytic NK cells displaying a mature phenotype and remarkable immuno-regulatory functions (NK-ireg). The main functional hallmark of these NK-ireg cells is represented by the surface expression/release of HLA-G, a major immunosuppressive molecule. In addition, NK-ireg cells secrete two powerful immuno-regulatory factors: IL-10 and IL-21. Through these factors, NK-ireg cells act as effectors of the down-regulation of the immune response: reconverting mature myeloid DC (mDC) into immature/tolerogenic DC, blocking cytolytic functions on conventional NK cells and inducing HLA-G membrane expression on PB-derived monocytes. The generation of "NK-ireg" cells is obtained, by default, in culture conditions favouring cell-to-cell contacts, and it is strictly dependent on reciprocal trans-presentation of membrane-bound IL-15 forms constitutively and selectively expressed by human CD34(+) PB-HP. Finally, a small subset of NKp46(+) HLA-G(+) IL-10(+) is detected within freshly isolated decidual NK cells, suggesting that these cells could represent an in vivo counterpart of the NK-ireg cells.

CONCLUSIONS/SIGNIFICANCE

In conclusion, NK-ireg cells represent a novel truly differentiated non-cytolytic NK subset with a self-sustainable phenotype (CD56(+) CD16(+) NKp30(+) NKp44(+) NKp46(+) CD94(+) CD69(+) CCR7(+)) generated from specific pSTAT6(+) GATA3(+) precursors. NK-ireg cells could be employed to develop new immuno-suppressive strategies in autoimmune diseases, transplant rejection or graft versus host diseases. In addition, NK-ireg cells can be easily derived from peripheral blood of the patients and could constitute an autologous biotherapic tool to be used combined or in alternative to other immuno-regulatory cells.

A common haplotype of the IL-31 gene influencing gene expression is associated with nonatopic eczema

BACKGROUND

IL-31 is a novel cytokine that, when overexpressed in transgenic mice, induces severe itching dermatitis resembling human eczema.

OBJECTIVE

We aimed to evaluate the importance of polymorphisms in the human IL-31 gene (IL31) in the genetic susceptibility to eczema.

METHODS

We sequenced the entire IL-31 gene, including the promoter region, and determined the haplotype structure. Single nucleotide polymorphisms tagging the main haplotypes were genotyped in 3 independent European populations comprising 690 affected families. An association analysis of IL31 gene variants with atopic and nonatopic eczema was performed.

RESULTS

We found significant association of a common IL31 haplotype with the nonatopic type of eczema in all 3 study populations (combined P = 4.5 x 10(-5)). Analysis of PBMCs in healthy individuals revealed a strong induction IL31 mRNA expression on stimulation with anti-CD3 and anti-CD28 that was 3.8-fold higher in individuals homozygous for the risk haplotype (AA) in contrast to non-A haplotype carriers, suggesting that altered regulation of IL-31 gene expression is the disease-causing factor.

CONCLUSION

Our results lend strong support to an important role of IL-31 in the pathogenesis of nonatopic eczema.

CLINICAL IMPLICATIONS

This study presents the first genetic risk factor for the nonatopic type of eczema and indicates a primary role of IL-31-induced pruritus in the initiation of this disease, thus proposing a new target for the prevention and therapy of eczema.