Essential vitamins for an effective T cell response

Calcitriol Impairs the Secretion of IL-4 and IL-13 in Th2 Cells via Modulating the VDR-Gata3-Gfi1 Axis

Calcitriol, the bioactive form of vitamin D, exerts its biological functions by binding to its cognate receptor, the vitamin D receptor (VDR). The indicators of the severity of allergies and asthma have been linked to low vitamin D levels. However, the role of calcitriol in regulating IL-4 and IL-13, two cytokines pivotal to allergic inflammation, remained unclear. Our study observed diminished IL-4 and IL-13 secretion in murine and human Th2 cells treated with calcitriol. In murine Th2 cells, Gata3 expression was attenuated by calcitriol. However, the expression of the transcriptional repressor Gfi1, too, was attenuated in the presence of calcitriol. Ectopic expression of either Gfi1 or VDR impaired the secretion of IL-13 in Th2 cells. In murine Th2 cells, VDR interacted with Gata3 but not Gfi1. Gfi1 significantly impaired Il13 promoter activation, which calcitriol failed to restore. Conversely, calcitriol augmented Gfi1 recruitment to the Il13 promoter. Ecr, a conserved region between these two genes, which enhanced the transactivation of Il4 and Il13 promoters, is essential for calcitriol-mediated suppression of both the genes. Calcitriol augmented the recruitment of VDR to the Il13 promoter and Ecr regions. Gata3 recruitment was significantly impaired at the Il13 and Ecr loci in the presence of calcitriol but increased at the Il4 promoter. Furthermore, the recruitment of the histone deacetylase HDAC1 was universally increased at the promoters of Il4, Il13, and Ecr when calcitriol was present. Together, our data clearly elucidate that calcitriol modulates VDR, Gata3, and Gfi1 to suppress IL-4 and IL-13 production in Th2 cells.

The Key Role of Vitamin D in Female Reproductive Health: A Narrative Review

Vitamin D, besides its crucial role in bone health and immune function, has received increased attention in recent years due to its possible impact on many processes related to female reproductive health. Recent research has tried to explain the role played by vitamin D in maintaining adequate hormonal status, fertility, and pregnancy outcomes. Our aim for this narrative literature review was to highlight and explain the mechanisms through which vitamin D status impacts female reproductive health. We believe this represents a very important subject of research, especially due to the increased incidence of infertility nowadays. Further studies are necessary on the association between vitamin D status and female reproductive health in order to fully understand its effects and to reach a consensus regarding vitamin D supplementation as a method to improve fertility status.

Calcitriol and Retinoic acid antagonize each other to suppress the production of IL-9 by Th9 cells

Distinct T helper cells, including Th9 cells help maintain homeostasis in the immune system. Vitamins play pivotal role in the immune system through many mechanisms, including regulating the differentiation of T helper cells. Calcitriol (1,25-dihydroxyvitamin D3) and retinoic acid possess hormone-like properties and are the bioactive metabolites of vitamin D and A, respectively, that signal through heterodimers containing the common retinoid X receptor. In contrast to individual treatment with the vitamins that significantly attenuates IL-9 production from Th9 cells, Th9 cells treated with both vitamins demonstrated IL-9 production similar to untreated Th9 cells. This is associated with reciprocal expression of PU.1 and Foxp3. While the recruitment of PU.1 was significantly impaired to the Il9 gene in the presence of calcitriol or retinoic acid in Th9 cells, addition of both vitamins together increased the recruitment of PU.1 to the Il9 gene. Calcitriol and retinoic acid together impaired the recruitment of HDAC1 to the Il9 gene without impacting Gcn5 recruitment. Importantly, retinoic acid negated the effect of calcitriol and impaired the binding of VDR on the Il9 gene by dampened VDR-RXR formation. Collectively, our data show that calcitriol and retinoic acid antagonize each other to regulate the differentiation of Th9 cells.

SOCS1 and pattern recognition receptors: TLR9 and RIG-I; novel haplotype associations in Egyptian fibrotic/cirrhotic patients with HCV genotype 4

In this paper we explore the role of suppressor of cytokine signaling 1 (SOCS1) (rs243327), the regulator of toll-like receptor-9 (TLR9) (rs352140), retinoic acid inducible gene-I (RIG-I) (rs669260), and cluster of differentiation 152 (CD152) (rs231776) in fibrotic/cirrhotic patients. Single nucleotide polymorphisms (SNPs) within these genes as well as haplotype analyses were performed on a cohort of 120 Egyptian fibrotic patients. Fibrosis had progressed from HCV genotype 4 infections. Using RT-PCR, SNPs were evaluated in the DNA collected from each patient using TaqMan® genotyping assays. A regression model was used to evaluate allelic and haplotypic associations with a fibrosis/cirrhotic scale. The necroinflammatory A score was adjusted for non-genetic covariates. The genotype distributions for SOCS1 (rs243327) and TLR-9 (rs352140) differed significantly between the F1-F3 and F3-F4 groups. On the other hand, the genotype distributions for RIG-I (rs669260) and CD152 (rs231776) genes did not significantly differ. The allele frequency was calculated using Hardy-Weinberg Equilibrium (HWE) for the SOCS1 (rs243327), RIG-I (rs669260), and CD152 (rs231776) genes. These calculated frequency values indicated the need to compare them to another population for that locus. However, TLR9 (rs352140) did not show similar results. The A allele in SOCS1, TLR9, and RIG-I SNPs was an adverse prognostic factor for liver fibrosis and liver activity. Haplotype analysis revealed a significant association between SOCS1 and TLR9 in fibrotic/cirrhotic patients. This indicated the presence of the A allele in either gene, which is considered a risk factor for the progression of liver disease to cirrhosis. SOCS1 rs243327, TLR9 rs352140, and RIG-I rs669260 polymorphisms might affect liver pathophysiology and the cirrhotic outcome following genotype 4 HCV infection. Therefore, performing this specific SNP testing may be of value for the stratification of the population at risk.

Epigenetic Treatment of Persistent Viral Infections

Preclinical Research Approximately 2,500 years ago, Hippocrates used the word herpes as a medical term to describe lesions that appeared to creep or crawl on the skin, advocating heat as a possible treatment. During the last 50 years, pharmaceutical research has made great strides, and therapeutic options have expanded to include small molecule antiviral agents, protease inhibitors, preventive vaccines for a handful of the papillomaviruses, and even cures for hepatitis C virus infections. However, effective treatments for persistent and recurrent viral infections, particularly the highly prevalent herpesviruses, continue to represent a significant unmet medical need, affecting the majority of the world's population. Exploring the population diversity of the human microbiome and the effects its compositional variances have on the immune system, health, and disease are the subjects of intense investigational research and study. Among the collection of viruses, bacteria, fungi, and single-cell eukaryotes that comprise the human microbiome, the virome has been grossly understudied relative to the influence it exerts on human pathophysiology, much as mitochondria have until recently failed to receive the attention they deserve, given their critical biomedical importance. Fortunately, cellular epigenetic machinery offers a wealth of druggable targets for therapeutic intervention in numerous disease indications, including those outlined above. With advances in synthetic biology, engineering our body's commensal microorganisms to seek out and destroy pathogenic species is clearly on the horizon. This is especially the case given recent breakthroughs in genetic manipulation with tools such as the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated) gene-editing platforms. Tying these concepts together with our previous work on the microbiome and neurodegenerative and neuropsychiatric diseases, we suggest that, because mammalian cells respond to a viral infection by triggering a cascade of antiviral innate immune responses governed substantially by the cell's mitochondria, small molecule carnitinoids represent a new class of therapeutics with potential widespread utility against many infectious insults. Drug Dev Res 78 : 24-36, 2017.   © 2016 Wiley Periodicals, Inc.