Regulation of cytokine and chemokine expression by histone lysine methyltransferase MLL1 in rheumatoid arthritis synovial fibroblasts.

Histone lysine methylation is thought to play a role in the pathogenesis of rheumatoid arthritis (RA). We previously reported aberrant expression of the gene encoding mixed-lineage leukemia 1 (MLL1), which catalyzes methylation of histone H3 lysine 4 (H3K4), in RA synovial fibroblasts (SFs). The aim of this study was to elucidate the involvement of MLL1 in the activated phenotype of RASFs. SFs were isolated from synovial tissues obtained from patients with RA or osteoarthritis (OA) during total knee joint replacement. MLL1 mRNA and protein levels were determined after stimulation with tumor necrosis factor α (TNFα). We also examined changes in trimethylation of H3K4 (H3K4me3) levels in the promoters of RA-associated genes (matrix-degrading enzymes, cytokines, and chemokines) and the mRNA levels upon small interfering RNA-mediated depletion of MLL1 in RASFs. We then determined the levels of H3K4me3 and mRNAs following treatment with the WD repeat domain 5 (WDR5)/MLL1 inhibitor MM-102. H3K4me3 levels in the gene promoters were also compared between RASFs and OASFs. After TNFα stimulation, MLL1 mRNA and protein levels were higher in RASFs than OASFs. Silencing of MLL1 significantly reduced H3K4me3 levels in the promoters of several cytokine (interleukin-6 [IL-6], IL-15) and chemokine (C-C motif chemokine ligand 2 [CCL2], CCL5, C-X-C motif chemokine ligand 9 [CXCL9], CXCL10, CXCL11, and C-X3-C motif chemokine ligand 1 [CX3CL1]) genes in RASFs. Correspondingly, the mRNA levels of these genes were significantly decreased. MM-102 significantly reduced the promoter H3K4me3 and mRNA levels of the CCL5, CXCL9, CXCL10, and CXCL11 genes in RASFs. In addition, H3K4me3 levels in the promoters of the IL-6, IL-15, CCL2, CCL5, CXCL9, CXCL10, CXCL11, and CX3CL1 genes were significantly higher in RASFs than OASFs. Our findings suggest that MLL1 regulates the expression of particular cytokines and chemokines in RASFs and is associated with the pathogenesis of RA. These results could lead to new therapies for RA.

New-onset of rheumatic diseases following COVID-19 vaccination: the report of three cases and a literature review.

Vaccines against coronavirus disease 2019 (COVID-19) have been distributed in most countries for the prevention of onset and aggravation of COVID-19. Recently, there have been increasing numbers of reports on new-onset autoimmune and autoinflammatory diseases following COVID-19 vaccination, however, only little information is available on the long-term safety of these vaccines. Here, we experienced three cases of new-onset rheumatic diseases following COVID-19 vaccination, one case each of rheumatoid arthritis (RA), anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and systemic lupus erythematosus (SLE). The symptom onset ranged from one day to a few days following vaccination. The patients of AAV and SLE were treated successfully with glucocorticoid therapy, and the patient of RA died due to COVID-19. In the literature review of new-onset rheumatic diseases following COVID-19 vaccination, which including seven cases of RA, 37 cases of AAV and 18 cases of SLE, the mean time from vaccination to onset was approximately 11 to 12 days. Most cases improved with glucocorticoid, immunosuppressive drugs and biologic agents. Although such adverse effects are rare, and vaccines are useful in prevent onset and severity of infections, continued accumulation of similar cases is important in terms of examining the long-term safety and understanding pathogenic mechanism of rheumatic diseases.

Epigenetic Dysregulation in the Pathogenesis of Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease in which immune disorders lead to autoreactive immune responses and cause inflammation and tissue damage. Genetic and environmental factors have been shown to trigger SLE. Recent evidence has also demonstrated that epigenetic factors contribute to the pathogenesis of SLE. Epigenetic mechanisms play an important role in modulating the chromatin structure and regulating gene transcription. Dysregulated epigenetic changes can alter gene expression and impair cellular functions in immune cells, resulting in autoreactive immune responses. Therefore, elucidating the dysregulated epigenetic mechanisms in the immune system is crucial for understanding the pathogenesis of SLE. In this paper, we review the important roles of epigenetic disorders in the pathogenesis of SLE.

New-onset Immune-mediated Necrotizing Myopathy and Trigeminal Neuropathy after SARS-CoV-2 mRNA Vaccination in a Patient with Rheumatoid Arthritis and Sjögren's Syndrome.

We present the case of a 42-year-old woman with rheumatoid arthritis and Sjögren's syndrome treated with adalimumab who developed immune-mediated necrotizing myopathy (IMNM) and trigeminal neuropathy after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination. Trigeminal neuralgia and elevated serum creatine kinase levels emerged 12 days post-vaccination, followed by myalgia in the femoral muscles. IMNM was histologically diagnosed. The pathogenesis may involve molecular mimicry between the SARS-CoV-2 spike glycoprotein and autologous tissues triggered by vaccination. This case emphasizes the association between SARS-CoV-2 vaccination, tumor necrosis factor inhibitor, IMNM, and trigeminal neuropathy, as well as the importance of monitoring immune-mediated adverse events following SARS-CoV-2 vaccination in patients with autoimmune disease.

Encapsulating Peritoneal Sclerosis in Systemic Lupus Erythematosus, Rheumatoid Arthritis, and Systemic Sclerosis.

We encountered a 57-year-old Japanese woman with encapsulating peritoneal sclerosis (EPS) in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and systemic sclerosis. The patient was admitted to our hospital because of ascites retention. Administration of tocilizumab, an anti-interleukin-6 receptor antibody, for her RA reduced the refractory ascites remarkably; however, she developed sudden acute gastrointestinal bleeding and died a year later. On autopsy, sclerotic thickening of the peritoneum showed diffuse infiltration of podoplanin-positive fibroblast-like cells, and a diagnosis of EPS was made. EPS rarely occurs in SLE, and tocilizumab may be a new treatment candidate for EPS.

New-onset Adult-onset Still's Disease Following COVID-19 Vaccination: Three Case Reports and a Literature Review.

Since December 2020, coronavirus disease 2019 (COVID-19) vaccines have been distributed in most countries to prevent the onset and aggravation of COVID-19. There is little information regarding the long-term safety of the vaccines. We report three cases and a literature review of new-onset adult-onset Still's disease (AOSD) that occurred following COVID-19 vaccination. Our cases include moderate to severe AOSD, and two were complicated with macrophage activation syndrome. Seventeen cases of new-onset or relapse of AOSD following COVID-19 vaccination, including 14 identified in the literature review and our 3 patients, were all treated successfully with glucocorticoid therapy, immunosuppressive drugs, or biologic agents.

Induction of memory-like CD8+ T cells and CD4+ T cells from human naive T cells in culture.

Memory T cells are crucial players in vertebrate adaptive immunity but their development is incompletely understood. Here, we describe a method to produce human memory-like T cells from naive human T cells in culture. Using commercially available human T-cell differentiation kits, both purified naive CD8+ T cells and purified naive CD4+ T cells were activated via T-cell receptor signaling and appropriate cytokines for several days in culture. All the T-cell activators were then removed from the medium and the cultures were continued in hypoxic condition (1% O2 atmosphere) for several more days; during this period, most of the cells died, but some survived in a quiescent state for a month. The survivors had small round cell bodies, expressed differentiation markers characteristic of memory T cells and restarted proliferation when the T-cell activators were added back. We could also induce memory-like T cells from naive human T cells without hypoxia, if we froze the activated T cells or prepared the naive T cells from chilled filter buffy coats.

Altered gene expression profiles of histone lysine methyltransferases and demethylases in rheumatoid arthritis synovial fibroblasts.

OBJECTIVES: Aberrant histone lysine methylation (HKM) has been reported in rheumatoid arthritis (RA) synovial fibroblasts (SFs). As histone lysine methyltransferases (HKMTs) and demethylases (HKDMs) regulate HKM, these enzymes are believed to be dysregulated in RASFs. The aim of this study is to clarify whether gene expressions of HKMTs and HKDMs are altered in RASFs. METHODS: SFs were isolated from synovial tissues obtained from RA or osteoarthritis (OA) patients during total knee joint replacement. The mRNA levels of 34 HKMTs and 22 HKDMs were examined after stimulation with tumour necrosis factor α (TNF-α) in RASFs and OASFs. RESULTS: The gene expression of the 12 HKMTs, including MLL1, MLL3, SUV39H1, SUV39H2, PRDM2, EZH2, SETD2, NSD2, NSD3, SMYD4, DOT1, and PR-set7, that catalyse the methylation of H3K4, H3K9, H3K27, H3K36, H3K79, or H4K20 was higher after TNFα stimulation in RASFs vs. OASFs. The gene expression of the 4 HKDMs, including FBXL10, NO66, JMJD2D, and FBXL11, that catalyse the methylation of H3K4, H3K9, or H3K36 was higher after TNFα stimulation in RASFs vs. OASFs. CONCLUSIONS: The study findings suggest that the HKM-modifying enzymes are involved in the alteration of HKM, which results in changes in the gene expression of RASFs.

Matrix Metalloproteinase Gene Activation Resulting from Disordred Epigenetic Mechanisms in Rheumatoid Arthritis.

Matrix metalloproteinases (MMPs) are implicated in the degradation of extracellular matrix (ECM). Rheumatoid arthritis (RA) synovial fibroblasts (SFs) produce matrix-degrading enzymes, including MMPs, which facilitate cartilage destruction in the affected joints in RA. Epigenetic mechanisms contribute to change in the chromatin state, resulting in an alteration of gene transcription. Recently, MMP gene activation has been shown to be caused in RASFs by the dysregulation of epigenetic changes, such as histone modifications, DNA methylation, and microRNA (miRNA) signaling. In this paper, we review the role of MMPs in the pathogenesis of RA as well as the disordered epigenetic mechanisms regulating MMP gene activation in RASFs.

The Histone Modification Code in the Pathogenesis of Autoimmune Diseases.

Autoimmune diseases are chronic inflammatory disorders caused by a loss of self-tolerance, which is characterized by the appearance of autoantibodies and/or autoreactive lymphocytes and the impaired suppressive function of regulatory T cells. The pathogenesis of autoimmune diseases is extremely complex and remains largely unknown. Recent advances indicate that environmental factors trigger autoimmune diseases in genetically predisposed individuals. In addition, accumulating results have indicated a potential role of epigenetic mechanisms, such as histone modifications, in the development of autoimmune diseases. Histone modifications regulate the chromatin states and gene transcription without any change in the DNA sequence, possibly resulting in phenotype alteration in several different cell types. In this paper, we discuss the significant roles of histone modifications involved in the pathogenesis of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, primary biliary cirrhosis, and type 1 diabetes.

The Mechanisms Underlying Chronic Inflammation in Rheumatoid Arthritis from the Perspective of the Epigenetic Landscape.

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that is characterized by synovial hyperplasia and progressive joint destruction. The activation of RA synovial fibroblasts (SFs), also called fibroblast-like synoviocytes (FLS), contributes significantly to perpetuation of the disease. Genetic and environmental factors have been reported to be involved in the etiology of RA but are insufficient to explain it. In recent years, accumulating results have shown the potential role of epigenetic mechanisms, including histone modifications, DNA methylation, and microRNAs, in the development of RA. Epigenetic mechanisms regulate chromatin state and gene transcription without any change in DNA sequence, resulting in the alteration of phenotypes in several cell types, especially RASFs. Epigenetic changes possibly provide RASFs with an activated phenotype. In this paper, we review the roles of epigenetic mechanisms relevant for the progression of RA.

Histone Methylation and STAT-3 Differentially Regulate Interleukin-6-Induced Matrix Metalloproteinase Gene Activation in Rheumatoid Arthritis Synovial Fibroblasts.

OBJECTIVE: Synovial fibroblasts (SFs) produce matrix-degrading enzymes that cause joint destruction in rheumatoid arthritis (RA). Epigenetic mechanisms play a pivotal role in autoimmune diseases. This study was undertaken to elucidate the epigenetic mechanism that regulates the transcription of matrix metalloproteinases (MMPs) in RASFs. METHODS: MMP gene expression and histone methylation profiles in the MMP promoters were examined in RASFs. The effect of WD repeat domain 5 (WDR5) silencing on histone methylation and MMP gene expression in RASFs was analyzed. MMP gene expression, surface expression of the interleukin-6 (IL-6) receptor, phosphorylation of STAT-3, and binding of STAT-3 in the MMP promoters were investigated in RASFs stimulated with IL-6. RESULTS: The MMP-1, MMP-3, MMP-9, and MMP-13 genes were actively transcribed in RASFs. Correspondingly, the level of histone H3 trimethylated at lysine 4 (H3K4me3) was elevated, whereas that of H3K27me3 was suppressed in the MMP promoters in RASFs. The decrease in H3K4me3 via WDR5 small interfering RNA reduced the levels of messenger RNA for MMP-1, MMP-3, MMP-9, and MMP-13 in RASFs. Interestingly, IL-6 signaling significantly increased the expression of MMP-1, MMP-3, and MMP-13, but not MMP-9, in RASFs. Although the IL-6 signaling pathway was similarly active in RASFs and osteoarthritis SFs, STAT-3 bound to the MMP-1, MMP-3, and MMP-13 promoters, but not the MMP-9 promoter, after IL-6 stimulation in RASFs. CONCLUSION: Our findings indicate that histone methylation and STAT-3 regulate spontaneous and IL-6-induced MMP gene activation in RASFs. The combination of chromatin structure and transcription factors may regulate distinct arthritogenic properties of RASFs.

A significant induction of neutrophilic chemoattractants but not RANKL in synoviocytes stimulated with interleukin 17.

Interleukin 17 (IL-17) is a cytokine implicated in the promotion of osteoclastogenesis. Its effect has been believed not to be directly exerted on osteoclast precursors, but rather indirectly carried out via an induction of receptor activator of NF-κB ligand (RANKL), the osteoclast differentiation factor, on osteoclast-supporting cells, which in turn exert an effect on osteoclast precursors. The mechanistic details, however, remain unclear. In this study, we first performed a transcriptome analysis of synoviocytes derived from a patient with rheumatoid arthritis cultured in the presence or absence of IL-17. We discovered that most of the genes significantly induced by IL-17 were chemokines with a chemotactic effect on neutrophils. We confirmed these results by quantitative RT-PCR and ELISA. Unexpectedly, the stimulation with IL-17 alone did not induce the expression of RANKL either at the mRNA or the protein level. The induction of RANKL was observed when IL-17 was added in combination with 1,25-dihydroxyvitamin D3 and prostaglandin E2, well-known inducers of RANKL, although the exact mechanism of this synergistic effect remains unclear. IL-6 and monocyte chemoattractant protein-1 were also significantly induced by IL-17 at both the mRNA and protein levels. Thus, it appears that IL-17 induces the migration of neutrophils and monocytes/macrophages through the activation of synoviocytes, and enhances a positive feedback loop composed of proinflammatory cytokines IL-6 and IL-17.

Aberrant histone acetylation contributes to elevated interleukin-6 production in rheumatoid arthritis synovial fibroblasts.

Accumulating evidence indicates that epigenetic aberrations have a role in the pathogenesis of rheumatoid arthritis (RA). However, reports on histone modifications are as yet quite limited in RA. Interleukin (IL)-6 is an inflammatory cytokine which is known to be involved in the pathogenesis of RA. Here we report the role of histone modifications in elevated IL-6 production in RA synovial fibroblasts (SFs). The level of histone H3 acetylation (H3ac) in the IL-6 promoter was significantly higher in RASFs than osteoarthritis (OA) SFs. This suggests that chromatin structure is in an open or loose state in the IL-6 promoter in RASFs. Furthermore, curcumin, a histone acetyltransferase (HAT) inhibitor, significantly reduced the level of H3ac in the IL-6 promoter, as well as IL-6 mRNA expression and IL-6 protein secretion by RASFs. Taken together, it is suggested that hyperacetylation of histone H3 in the IL-6 promoter induces the increase in IL-6 production by RASFs and thereby participates in the pathogenesis of RA.

Combination of tumor necrosis factor α and interleukin-6 induces mouse osteoclast-like cells with bone resorption activity both in vitro and in vivo.

OBJECTIVE: To clarify the function of osteoclast-like multinuclear cells differentiated from bone marrow-derived macrophages (BMMs) by a combination of tumor necrosis factor α (TNFα) and interleukin-6 (IL-6), and to investigate the molecular mechanisms underlying the differentiation. METHODS: BMMs were stimulated by TNFα and/or IL-6. The cells were then compared with conventional osteoclasts differentiated in vitro by RANKL. An in vitro pit formation assay on dentine slices and an in vivo resorption assay of calvarial bones were performed. We also evaluated the activities and expression levels of NF-κB, c-Fos, and NF-ATc1, which are essential to the differentiation of conventional osteoclasts. Small interfering RNA was used to knock down c-Fos. The effects of genetic ablation of STAT-3 and pharmacologic inhibitors of NF-AT, JAK, and ERK were also studied. RESULTS: Osteoclast-like cell differentiation depended on TNFα and IL-6 and was not inhibited by osteoprotegerin. These differentiated cells were associated with both in vitro and in vivo bone resorption activity. TNFα and IL-6 had a synergistic effect on the activity and expression of c-Fos. Knockdown of c-Fos inhibited the expression of NF-ATc1 and the differentiation of osteoclast-like cells. All of these inhibitors blocked differentiation of the cells in vitro, but surprisingly, the conditional knockout of STAT-3 did not. Tofacitinib also inhibited the bone destruction caused by TNFα and IL-6 in vivo. CONCLUSION: Our results demonstrate that a combination of the inflammatory cytokines TNFα and IL-6 can induce osteoclast-like cells that have in vitro and in vivo bone-resorptive activity.

The molecular basis of the memory T cell response: differential gene expression and its epigenetic regulation.

How the immune system remembers a previous encounter with a pathogen and responds more efficiently to a subsequent encounter has been one of the central enigmas for immunologists for over a century. The identification of pathogen-specific memory lymphocytes that arise after an infection provided a cellular basis for immunological memory. But the molecular mechanisms of immunological memory remain only partially understood. The emerging evidence suggests that epigenetic changes have a key role in controlling the distinct transcriptional profiles of memory lymphocytes and thus in shaping their function. In this Review, we summarize the recent progress that has been made in assessing the differential gene expression and chromatin modifications in memory CD4(+) and CD8(+) T cells, and we present our current understanding of the molecular basis of memory T cell function.

[Role of histone modifications in differentiation and effector function of CD8 T cells: update review including genome-wide analysis].

Evidence including genome-wide analyses have uncovered that epigenetic mechanisms regulate differentiation and effector functions in CD8 T cells. Gene expression profiles change when CD8 T cells differentiate from naïve T cells to memory T cells. It has been shown that this programmed differentiation is regulated by epigenetic mechanisms. Upon antigen stimulation, CD8 T cells activate and acquire effector functions to target cells. Effector molecule gene expressions are upregulated by epigenetic mechanisms in CD8 T cells. It is suggested that memory T cells respond more rapidly to antigens because chromatin structures of effector molecule genes are open and their gene transcriptions are poised for activation.

Marked induction of c-Maf protein during Th17 cell differentiation and its implication in memory Th cell development.

Until recently, effector T helper (Th) cells have been classified into two subsets, Th1 and Th2 cells. Since the discovery of Th17 cells, which produce IL-17, much attention has been given to Th17 cells, mainly because they have been implicated in the pathogenesis of various inflammatory diseases. We have performed transcriptome analysis combined with factor analysis and revealed that the expression level of c-Maf, which is considered to be important for Th2 differentiation, increases significantly during the course of Th17 differentiation. The IL-23 receptor (IL-23R), which is important for Th17 cells, is among putative transcriptional targets of c-Maf. Interestingly, the analysis of c-Maf transgenic Th cells revealed that the overexpression of c-Maf did not lead to the acceleration of the early stage of Th17 differentiation but rather to the expansion of memory phenotype cells, particularly with Th1 and Th17 traits. Consistently, mouse wild-type memory Th cells expressed higher mRNA levels of c-Maf, IL-23R, IL-17, and IFN-γ than control cells; in contrast, Maf(-/-) memory Th cells expressed lower mRNA levels of those molecules. Thus, we propose that c-Maf is important for the development of memory Th cells, particularly memory Th17 cells and Th1 cells.

Genome-wide analysis of histone methylation reveals chromatin state-based regulation of gene transcription and function of memory CD8+ T cells.

Memory lymphocytes are characterized by their ability to exhibit a rapid response to the recall antigen, in which differential transcription is important, yet the underlying mechanism is not understood. We report here a genome-wide analysis of histone methylation on two histone H3 lysine residues (H3K4me3 and H3K27me3) and gene expression profiles in naive and memory CD8(+) T cells. We found that specific correlation exists between gene expression and the amounts of H3K4me3 (positive correlation) and H3K27me3 (negative correlation) across the gene body. These correlations displayed four distinct modes (repressive, active, poised, and bivalent), reflecting different functions of these genes in CD8(+) T cells. Furthermore, a permissive chromatin state of each gene was established by a combination of different histone modifications. Our findings reveal a complex regulation by histone methylation in differential gene expression and suggest that histone methylation may be responsible for memory CD8(+) T cell function.

Histone acetylation facilitates rapid and robust memory CD8 T cell response through differential expression of effector molecules (eomesodermin and its targets: perforin and granzyme B).

To understand the mechanism regulating the effector function of memory CD8 T cells, we examined expression and chromatin state of a key transcription factor (eomesodermin, EOMES) and two of its targets: perforin (PRF1) and granzyme B (GZMB). Accessible chromatin associated histone 3 lysine 9 acetylation (H3K9Ac) was found significantly higher at the proximal promoter and the first exon region of all three genes in memory CD8 T cells than in naive CD8 T cells. Correspondingly, EOMES and PRF1 were constitutively higher expressed in memory CD8 T cells than in naive CD8 T cells at resting and activated states. In contrast, higher expression of GZMB was induced in memory CD8 T cells than in naive CD8 T cells only after activation. Regardless of their constitutive or inducible expression, decreased H3K9Ac levels after treatment with a histone acetyltransferase inhibitor (Curcumin) led to decreased expression of all three genes in activated memory CD8 T cells. These findings suggest that H3K9Ac associated accessible chromatin state serves as a corner stone for the differentially high expression of these effector genes in memory CD8 T cells. Thus, epigenetic changes mediated via histone acetylation may provide a chromatin "memory" for the rapid and robust transcriptional response of memory CD8 T cells.