IL-15 prolongs CD154 expression on human CD4 T cells via STAT5 binding to the CD154 transcriptional promoter

Extensive fragmentation and re-organization of transcription in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is the prototype of autoimmune diseases, characterized by extensive gene expression perturbations in peripheral blood immune cells. Circumstantial evidence suggests that these perturbations may be due to altered epigenetic profiles and chromatin accessibility but the relationship between transcriptional deregulation and genome organization remains largely unstudied. In this work we propose a genomic approach that leverages patterns of gene coexpression from genome-wide transcriptome profiles in order to identify statistically robust Domains of Co-ordinated gene Expression (DCEs). Application of this method on a large transcriptome profiling dataset of 148 SLE patients and 52 healthy individuals enabled the identification of significant disease-associated alterations in gene co-regulation patterns, which also correlate with SLE activity status. Low disease activity patient genomes are characterized by extensive fragmentation leading to overall fewer DCEs of smaller size. High disease activity genomes display extensive redistribution of co-expression domains with expanded and newly-appearing (emerged) DCEs. The dynamics of domain fragmentation and redistribution are associated with SLE clinical endophenotypes, with genes of the interferon pathway being highly enriched in DCEs that become disrupted and with functions associated to more generalized symptoms, being located in domains that emerge anew in high disease activity genomes. Our results suggest strong links between the SLE phenotype and the underlying genome structure and underline an important role for genome organization in shaping gene expression in SLE.

Extracellular Vesicles Derived from Human Umbilical Cord Mesenchymal Stem Cells Protect Liver Ischemia/Reperfusion Injury by Reducing CD154 Expression on CD4+ T Cells via CCT2

As a cause of postoperative complications and early hepatic failure after liver transplantation, liver ischemia/reperfusion injury (IRI) still has no effective treatment during clinical administration. Although the therapeutic potential of mesenchymal stem cells (MSCs) for liver IRI has been previously shown, the underlying mechanisms are not completely clear. It is accepted that MSC-derived extracellular vesicles (MSC-EVs) are newly uncovered messengers for intercellular communication. Herein, it is reported that umbilical cord-derived MSCs (UC-MSCs) improve liver IRI in mice through their secreted EVs. It is also visualized that UC-MSC-EVs mainly concentrate in liver after 6 h of reperfusion. Furthermore, UC-MSC-EVs are found to significantly modulate the membranous expression of CD154 of intrahepatic CD4+ T cells, which is an initiation of inflammatory response in liver and can aggravate liver IRI. Mechanistically, protein mass spectrum analysis is performed and it is revealed that Chaperonin containing TCP1 subunit 2 (CCT2) enriches in UC-MSC-EVs, which regulates the calcium channels to affect Ca2+ influx and suppress CD154 synthesis in CD4+ T cells. In conclusion, these results highlight the therapeutic potential of UC-MSC-EVs in attenuating liver IRI. This finding suggests that CCT2 from UC-MSC-EVs can modulate CD154 expression of intrahepatic CD4+ T cells during liver IRI through the Ca2+-calcineurin-NFAT1 signaling pathway.

Tumor necrosis factor-α blockade treatment decreased CD154 (CD40-ligand) expression in rheumatoid arthritis

Contexts

CD154 (commonly referred to as CD40-ligand) is a critical T cell factor that participates in the pathogenesis of autoimmune and is over-expressed in rheumatoid arthritis (RA). TNF-α blockade treatment had dramatic efficacy in RA.

Objective

To investigate whether TNF-α blockade treatment can inhibit CD154 expression in RA.

Methods

Blood samples were collected from 33 patients with rheumatoid arthritis before and 3 months after TNF-α blockade treatment. Clinical serological data determined by standard assays and T cell CD154 expression levels determined by flow cytometry were statistically analyzed for these two time points.

Results

The percentage of CD154 expression on gated CD4+ T cells of PBMCs from RA patients after 3 months TNF-α blockade treatment was significantly lower than before treatment (2.94 ± 3.21% vs. 7.21 ± 5.64%; p = 0.0001). The disease activity and anti-CCP antibody levels were also significantly reduced after TNF-α blockade treatment. The CD154 expression levels were positively correlated with disease activity index DAS28, and CRP. The post-stimulated CD154 expression percentage of purified CD4+ T cells between baseline and after TNF-α blockade treatment was not significantly different (p = 0.221). Baseline CD154 levels were positively correlated with treatment-induced changes in DAS28 (p = 0.014; r2 = 0.187).

Conclusions

TNF-α blockade treatment significantly decreased the CD154 expression on CD4+ T cells, disease activity and anti-CCP antibody simultaneously in RA patients. However TNF-α blockade did not impair T cell capacity to express CD154 after stimulation. These results suggest that decreased CD154 expression after TNF-α blockade may be due to decreased RA disease activity but not direct inhibition of CD154 responsiveness of T cells.

Hydroxychloroquine inhibits CD154 expression in CD4+ T lymphocytes of systemic lupus erythematosus through NFAT, but not STAT5, signaling

Background

Overexpression of membranous CD154 in T lymphocytes has been found previously in systemic lupus erythematosus (SLE). Because hydroxychloroquine (HCQ) has been used frequently in the treatment of lupus, we sought to identify the effects of HCQ on CD154 and a possibly regulatory mechanism.

Methods

CD4⁺ T cells were isolated from the blood of lupus patients. After stimulation with ionomycin or IL-15 and various concentrations of HCQ, expression of membranous CD154 and NFAT and STAT5 signaling were assessed.

Results

HCQ treatment had significant dose-dependent suppressive effects on membranous CD154 expression in ionomycin-activated T cells from lupus patients. Furthermore, HCQ inhibited intracellular sustained calcium storage release, and attenuated the nuclear translocation of NFATc2 and the expression of NFATc1. However, CD154 expressed through IL-15-mediated STAT5 signaling was not inhibited by HCQ treatment.

Conclusions

HCQ inhibited NFAT signaling in activated T cells and blocked the expression of membranous CD154, but not STAT5 signaling. These findings provide a mechanistic insight into SLE in HCQ treatment.

Scaffold protein JLP mediates TCR-initiated CD4+T cell activation and CD154 expression

CD4⁺ T-cell activation and its subsequent induction of CD154 (CD40 ligand, CD40L) expression are pivotal in shaping both the humoral and cellular immune responses. Scaffold protein JLP regulates signal transduction pathways and molecular trafficking inside cells, thus represents a critical component in maintaining cellular functions. Its role in regulating CD4⁺ T-cell activation and CD154 expression, however, is unclear. Here, we demonstrated expression of JLP in mouse tissues of lymph nodes, thymus, spleen, and also CD4⁺ T cells. Using CD4+ T cells from jlp-deficient and jlp-wild-type mice, we demonstrated that JLP-deficiency impaired T-cell proliferation, IL-2 production, and CD154 induction upon TCR stimulations, but had no impacts on the expression of other surface molecules such as CD25, CD69, and TCR. These observed impaired T-cell functions in the jlp-/- CD4⁺ T cells were associated with defective NF-AT activation and Ca²⁺ influx, but not the MAPK, NF-κB, as well as AP-1 signaling pathways. Our findings indicated that, for the first time, JLP plays a critical role in regulating CD4⁺ T cells response to TCR stimulation partly by mediating the activation of TCR-initiated Ca²⁺/NF-AT.

Signal transducer and activator of transcription 5 is implicated in disease activity in adult and juvenile onset systemic lupus erythematosus

The Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway is one of a handful of pleiotropic cascades used to transduce a multitude of signals for development and homeostasis in humans. It is the principal signaling mechanism for a wide array of cytokines and growth factors. Dysregulated cytokine action on immune cells plays an important role in the initiation and progress of systemic lupus erythematosus (SLE). In this study, we tried to assess the role of STAT5 in systemic lupus erythematosus and correlate its phosphorylation level with the disease activity. The activation of the STAT5 was assessed by measuring the level of expression of phosphorylated STAT5 (pSTAT5) using flow cytometry on the peripheral blood T and B cells in 58 SLE patients (40 adult and 18 juvenile onset) and on 23 healthy age- and sex-matched controls for both groups. Serum prolactin level was also assessed in the patients and control by ELISA. The study revealed that the level of pSTAT5 was higher in adult SLE patients than in healthy control (p = 0.001) and in juvenile-onset SLE patients versus age-matched control (p = 0.031). A positive correlation existed between the pSTAT5 levels and Systemic Lupus Activity Measure (SLAM) score and also with multiple clinical manifestations indicating a potential role of STAT5 signaling in pathogenesis SLE. The pSTAT5 signaling is implicated in the disease activity of SLE and may be a useful target of therapy by correcting the dysregulation of cytokines involved in the disease pathogenesis.