Interferon regulatory factor-4 activates IL-2 and IL-4 promoters in cooperation with c-Rel

Challenges for the Newborn Immune Response to Respiratory Virus Infection and Vaccination

The initial months of life reflect an extremely challenging time for newborns as a naïve immune system is bombarded with a large array of pathogens, commensals, and other foreign entities. In many instances, the immune response of young infants is dampened or altered, resulting in increased susceptibility and disease following infection. This is the result of both qualitative and quantitative changes in the response of multiple cell types across the immune system. Here we provide a review of the challenges associated with the newborn response to respiratory viral pathogens as well as the hurdles and advances for vaccine-mediated protection.

LncRNA Neat1 positively regulates MAPK signaling and is involved in the pathogenesis of Sjögren's syndrome

OBJECTIVE

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease characterized by lymphocytic infiltration of the exocrine glands. Recent, studies have shown that the long noncoding RNA (lncRNA) NEAT1 plays a crucial role in regulating the immune response. However, studies on the lncRNA NEAT1 in pSS are limited. Exploring the role of the lncRNA NEAT1 in the pathogenesis of pSS was the purpose of this study.

METHODS

The expression of NEAT1 in peripheral blood mononuclear cells (PBMCs) of patients with pSS and healthy controls (HCs) was analyzed by real-time polymerase chain reaction (RT-PCR). Antisense oligonucleotides (ASOs) and siRNA or immune stimulation with PMA/ionomycin were used to perform loss-and-gain-of-function experiments. RT-PCR, enzyme-linked immunosorbent assay (ELISA), and Western blot were performed to detect the RNA and protein levels of specific genes induced by PMA/ionomycin stimulation. Microarray analysis was used to generate an overview of the genes that might be regulated by NEAT1.

RESULTS

Compared with that in HC patient cells, the expression of NEAT1 in pSS patients was mainly increased in peripheral T cells, including CD4⁺ and CD8⁺ T cells. Additionally, the expression of NEAT1 in CD4⁺ T cells of patients with pSS was positively correlated with the course of disease. NEAT1 expression in Jurkat cells was induced by PMA/ionomycin stimulation upon activation of the TCR-p38 pathway. Upregulation of NEAT1 expression also increased the expression of CXCL8 and TNF-α. Knocking down NEAT1 expression with an ASO suppressed the expression of CXCL8 and TNF-α in PMA/ionomycin-stimulated Jurkat cells. Then, we found that NEAT1 regulated the activation of MAPK pathway to regulate NEAT1-induced factors, selectively activating the expression of p-p38 and p-ERK1/2. Furthermore, we also detected the expression profile of Jurkat cells stimulated by PMA/ionomycin when NEAT1 was silenced or not, in order to produce an overview of NEAT1-regulated genes.

CONCLUSION

These results provide a new understanding of the mechanisms of pSS and reveal that NEAT1 is a positive regulator of pSS, which is of substantial significance to its pathogenesis. Thus, NEAT1 provides a potential therapeutic target for pSS.

MicroRNA-3662 expression correlates with antiviral drug resistance in adult T-cell leukemia/lymphoma cells

Interferon regulatory factor (IRF) 4 and the proto-oncogene c-Rel cooperate in growth and antiviral drug resistance of adult T-cell leukemia/lymphoma (ATLL). To elucidate the target of IRF4 and c-Rel in ATLL, we determined the simultaneous binding sites of IRF4 and c-Rel using ChIP-seq technology. Nine genes were identified within 2 kb of binding sites, including MIR3662. Expression of miR-3662 was regulated by IRF4, and to a lesser extent by c-Rel. Cell proliferation was inhibited by knockdown of miR-3662 and expression of miR-3662 was correlated with antiviral drug resistance in ATLL cell lines. Thus, miR-3662 represents a target for therapies against ATLL.

An activating mutation of interferon regulatory factor 4 (IRF4) in adult T-cell leukemia

The human T-cell leukemia virus-1 (HTLV-1) oncoprotein Tax drives cell proliferation and resistance to apoptosis early in the pathogenesis of adult T-cell leukemia (ATL). Subsequently, probably as a result of specific immunoediting, Tax expression is down-regulated and functionally replaced by somatic driver mutations of the host genome. Both amplification and point mutations of interferon regulatory factor 4 (IRF4) have been previously detected in ATL., K59R is the most common single-nucleotide variation of IRF4 and is found exclusively in ATL. High-throughput whole-exome sequencing revealed recurrent activating genetic alterations in the T-cell receptor, CD28, and NF-κB pathways. We found that IRF4, which is transcriptionally activated downstream of these pathways, is frequently mutated in ATL. IRF4 RNA, protein, and IRF4 transcriptional targets are uniformly elevated in HTLV-1-transformed cells and ATL cell lines, and IRF4 was bound to genomic regulatory DNA of many of these transcriptional targets in HTLV-1-transformed cell lines. We further noted that the K59R IRF4 mutant is expressed at higher levels in the nucleus than WT IRF4 and is transcriptionally more active. Expression of both WT and the K59R mutant of IRF4 from a constitutive promoter in retrovirally transduced murine bone marrow cells increased the abundance of T lymphocytes but not myeloid cells or B lymphocytes in mice. IRF4 may represent a therapeutic target in ATL because ATL cells select for a mutant of IRF4 with higher nuclear expression and transcriptional activity, and overexpression of IRF4 induces the expansion of T lymphocytes in vivo.

Human amniotic epithelial cells inhibit CD4+ T cell activation in acute kidney injury patients by influencing the miR-101-c-Rel-IL-2 pathway

In the pathogenesis of acute kidney injury (AKI), the release of multiple interleukins can lead to increased kidney damage. Human amniotic epithelial cells (HuAECs) can inhibit immune cell activation in vivo and in vitro. We hypothesized that HuAECs could weaken patient-derived peripheral blood CD4+ T-cell activation and decreasing the ability of these cells to express and release IL-2. -Cell proliferation assay revealed that under the same culture conditions, activated AKI patient-derived CD4+ T cells had a significantly reduced proliferation rate when were co-cultured with HuAECs. And the level of IL-2 released was also significantly reduced. Western blot and qRT-PCR assays showed that the expression of c-Rel in the CD4+ T cells was also significantly reduced. However, the expression level of endogenous miR-101 in the CD4+ T cells co-cultured with HuAECs was significantly increased. Luciferase reporter assay results suggested that miR-101 could bind to a specific site in the c-Rel 3' UTR and induce the post-transcriptional silencing of c-Rel. Subsequently, we over-expressed miR-101 in AKI patient-derived CD4+ T cells. The qRT-PCR and western blot assay results revealed that the expression of endogenous c-Rel was significantly reduced, while the ELISA results indicated that the level of IL-2 released was also significantly decreased. Finally, ChIP-PCR assay results showed that the miR-101-overexpressing CD4+ T-cell group and the HuAEC co-culture CD4+ T-cell group exhibited significantly decreased binding capacities between the 'c-Rel-NFκB' complex and the IL-2 gene promoter, and the transcriptional activity of IL-2 was also significantly decreased. Therefore, we confirmed that HuAECs can stimulate miR-101 expression in AKI patient-derived peripheral blood CD4+ T cells, thus inhibiting the expression of the miR-101 target gene c-Rel and leading to a reduction in IL-2 expression and release.

Association of REL polymorphisms and outcome of patients with septic shock

Background

cRel, a subunit of NF-κB, is implicated in the inflammatory response observed in autoimmune disease. Hence, knocked-out mice for cRel had a significantly higher mortality, providing new and important functions of cRel in the physiopathology of septic shock. Whether genetic variants in the human REL gene are associated with severity of septic shock is unknown.

Methods

We genotyped a population of 1040 ICU patients with septic shock and 855 ICU controls for two known polymorphisms of REL; REL rs842647 and REL rs13031237. Outcome of patients according to the presence of REL variant alleles was compared.

Results

The distribution of REL variant alleles was not significantly different between patients and controls. Among the septic shock group, REL rs13031237*T minor allele was not associated with worse outcome. In contrast, REL rs842647*G minor allele was significantly associated with more multi-organ failure and early death [OR 1.4; 95 % CI (1.02–1.8)].

Conclusion

In a large ICU population, we report a significant clinical association between a variation in the human REL gene and severity and mortality of septic shock, suggesting for the first time a new insight into the role of cRel in response to infection in humans.

Smad2/3 and IRF4 play a cooperative role in IL-9-producing T cell induction

IL-9 is a pleiotropic cytokine that can regulate autoimmune and allergic responses. Th9 cells can develop from naive T cells or Th2 cells through stimulation by TGF-β in vitro. In this study, we demonstrated that Smad2 and Smad3 are necessary for IL-9 production from T cells in an OVA-induced asthma model using T cell-specific Smad2- and Smad3-deficient mice. Smad2 and Smad3 were also redundantly essential for TGF-β signaling to induce histone modifications for Il9 transcription. Although Smad2/3 was recruited to the Il9 promoter by TGF-β stimulation, they are not sufficient to activate the Il9 promoter. By the screening the transcription factors, we found that IFN regulatory factor 4 (IRF4) was essential for the Smad2/3-mediated Il9 promoter activation. In addition, Smad2/3 physically interacted with IRF4, and Smad2/3 did not bind to the Il9 promoter and could not induce Th9 in IRF4-deficient T cells. Similarly, IRF4 could not stimulate Il9 transcription in the absence of Smad2/3, and TGF-β enhanced IRF4 recruitment to the Il9 promoter in a Smad2/3-dependent manner. We propose that Smad2/3 and IRF4 cooperatively transactivate the Il9 promoter and play an important role in regulating allergic immune responses by inducing Th9 cells.

Roles of c-Rel signalling in inflammation and disease

Nuclear factor kappa B (NFκB) is a dimeric transcription factor comprised of five family members RelA (p65), RelB, c-Rel, p50 and p52. NFκB signalling is complex and controls a myriad of normal cellular functions. However, constitutive or aberrant activation of this pathway is associated with disease progression and cancer in multiple organs. The diverse array of biological responses is modulated by many factors, including the activating stimulus, recruitment of co-regulatory molecules, consensus DNA binding sequence, dimer composition and post-translational modifications. Each subunit has very different biological functions and in the context of disease the individual subunits forming the NFκB dimer can have a profound effect, causing a shift in the balance from normal to pathogenic signalling. Here we discuss the role of c-Rel dependant signalling in normal physiology and its contribution to disease both inside and outside of the immune system.