Prolactin activates IRF1 and leads to altered balance of histone acetylation: Implications for systemic lupus erythematosus

Recent advances in the involvement of epigenetics in the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a typical systemic autoimmune disease that manifests as skin rash, arthritis, lymphadenopathy, and multiple organ lesions. Epigenetics, including DNA methylation, histone modification, and non-coding RNA regulation, mainly affect the function and characteristics of cells through the regulation of gene transcription or translation. Increasing evidence indicates that there are a variety of complex epigenetic effects in patients with SLE, which interfere with the differentiation and function of T, and B lymphocytes, monocytes, and neutrophils, and enhance the expression of SLE-associated pathogenic genes. This paper summarizes our currently knowledge regarding pathogenesis of SLE, and introduces current advances in the epigenetic regulation of SLE from three aspects: immune function, inflammatory response, and lupus complications. We propose that epigenetic changes could be used as potential biomarkers and therapeutic targets of SLE.

The effect of prolactin on immune cell subsets involved in SLE pathogenesis

The higher frequency of autoimmune diseases in the female population compared to males suggests that certain hormones, such as prolactin (PRL), play a role in determining the prevalence of autoimmunity in women, particularly during childbearing age. PRL can act not only as a hormone but also as a cytokine, being able to modulate immune responses. Hyperprolactinemia has been implicated in the pathogenesis of various autoimmune diseases where it may affect disease activity. One of the conditions where PRL has such a role is systemic lupus erythematosus (SLE). PRL regulates the proliferation and survival of both lymphoid and myeloid cells. It also affects the selection of T-cell repertoires by influencing the thymic microenvironment. In autoimmune conditions, PRL interferes with the activity of regulatory T cells. It also influences B cell tolerance by lowering the activation threshold of anergic B cells. The production of CD40L and cytokines, such as interleukin IL-6, are also promoted by PRL. This, in turn, leads to the production of autoantibodies, one of the hallmarks of SLE. PRL increases the cytotoxic activity of T lymphocytes and the secretion of proinflammatory cytokines. The production of proinflammatory cytokines, particularly those belonging to the type 1 interferon (IFN) family, is part of the SLE characteristic genetic signature. PRL also participates in the maturation and differentiation of dendritic cells, promoting the presentation of autoantigens and high IFNα secretion. It also affects neutrophil function and the production of neutrophil traps. Macrophages and dendritic cells can also be affected by PRL, linking this molecule to the abnormal behavior of both innate and adaptive immune responses.This review aimed to highlight the importance of PRL and its actions on the cells of innate and adaptive immune responses. Additionally, by elucidating the role of PRL in SLE etiopathogenesis, this work will contribute to a better understanding of the factors involved in SLE development and regulation.

Resilience in Long-Term Viral Infection: Genetic Determinants and Interactions

Virus-induced neurological sequelae resulting from infection by Theiler's murine encephalomyelitis virus (TMEV) are used for studying human conditions ranging from epileptic seizures to demyelinating disease. Mouse strains are typically considered susceptible or resistant to TMEV infection based on viral persistence and extreme phenotypes, such as demyelination. We have identified a broader spectrum of phenotypic outcomes by infecting strains of the genetically diverse Collaborative Cross (CC) mouse resource. We evaluated the chronic-infection gene expression profiles of hippocampi and thoracic spinal cords for 19 CC strains in relation to phenotypic severity and TMEV persistence. Strains were clustered based on similar phenotypic profiles and TMEV levels at 90 days post-infection, and we categorized distinct TMEV response profiles. The three most common profiles included "resistant" and "susceptible," as before, as well as a "resilient" TMEV response group which experienced both TMEV persistence and mild neurological phenotypes even at 90 days post-infection. Each profile had a distinct gene expression signature, allowing the identification of pathways and networks specific to each TMEV response group. CC founder haplotypes for genes involved in these pathways/networks revealed candidate response-specific alleles. These alleles demonstrated pleiotropy and epigenetic (miRNA) regulation in long-term TMEV infection, with particular relevance for resilient mouse strains.

Epigenetic linkage of systemic lupus erythematosus and nutrition

The term "epigenetics" refers to a series of meiotically/mitotically inheritable alterations in gene expression, related to environmental factors, without disruption on DNA sequences of bases. Recently, the pathophysiology of autoimmune diseases (ADs) has been closely linked to epigenetic modifications. Actually, epigenetic mechanisms can modulate gene expression or repression of targeted cells and tissues involved in autoimmune/inflammatory conditions acting as keys effectors in regulation of adaptive and innate responses. ADs, as systemic lupus erythematosus (SLE), a rare disease that still lacks effective treatment, is characterized by epigenetic marks in affected cells.Taking into account that epigenetic mechanisms have been proposed as a winning strategy in the search of new more specific and personalized therapeutics agents. Thus, pharmacology and pharmacoepigenetic studies about epigenetic regulations of ADs may provide novel individualized therapies. Focussing in possible implicated factors on development and predisposition of SLE, diet is feasibly one of the most important factors since it is linked directly to epigenetic alterations and these epigenetic changes may augment or diminish the risk of SLE. Nevertheless, several studies have guaranteed that dietary therapy could be a promise to SLE patients via prophylactic actions deprived of side effects of pharmacology, decreasing co-morbidities and improving lifestyle of SLE sufferers.Herein, we review and discuss the cross-link between epigenetic mechanisms on SLE predisposition and development, as well as the influence of dietary factors on regulation epigenetic modifications that would eventually make a positive impact on SLE patients.

Identification of hub genes, pathways, and related transcription factors in systemic lupus erythematosus: A preliminary bioinformatics analysis

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple organ damage and the production of a variety of autoantibodies. The pathogenesis of SLE has not been fully defined, and it is difficult to treat. Our study aimed to identify candidate genes that may be used as biomarkers for the screening, diagnosis, and treatment of SLE.

METHODS

We used the GEO2R tool to identify the differentially expressed genes (DEGs) in SLE-related datasets retrieved from the Gene Expression Omnibus (GEO). In addition, we also identified the biological functions of the DEGs by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Additionally, we constructed protein-protein interaction (PPI) networks to identify hub genes, as well as the regulatory network of transcription factors related to DEGs.

RESULTS

Two datasets were identified for use from the GEO (GSE50772, GSE4588), and 34 up-regulated genes and 4 down-regulated genes were identified by GEO2R. Pathway analysis of the DEGs revealed enrichment of the interferon alpha/beta signaling pathway; GO analysis was mainly enriched in response to interferon alpha, regulation of ribonuclease activity. PPIs were constructed through the STRING database and 14 hub genes were selected and 1 significant module (score = 12.923) was obtained from the PPI network. Additionally, 11 key transcription factors that interacted closely with the 14 hub DEGs were identified from the gene transcription factor network.

CONCLUSIONS

Bioinformatic analysis is an effective tool for screening the original genomic data in the GEO database, and a large number of SLE-related DEGs were identified. The identified hub DEGs may be potential biomarkers of SLE.