CCAAT/Enhancer-binding protein β promotes pathogenesis of EAE

C/EBPβ: The structure, regulation, and its roles in inflammation-related diseases

Inflammation, a mechanism of the human body, has been implicated in many diseases. Inflammatory responses include the release of inflammatory mediators by activating various signaling pathways. CCAAT/enhancer binding protein β (C/EBPβ), a transcription factor in the C/EBP family, contains the leucine zipper (bZIP) domain. The expression of C/EBPβ is mediated at the transcriptional and post-translational levels, such as phosphorylation, acetylation, methylation, and SUMOylation. C/EBPβ has been involved in inflammatory responses by mediating several signaling pathways, such as MAPK/NF-κB and IL-6/JAK/STAT3 pathways. C/EBPβ plays an important role in the pathological development of inflammation-related diseases, such as osteoarthritis, pneumonia, hepatitis, inflammatory bowel diseases, and rheumatoid arthritis. Here, we comprehensively discuss the structure and biological effects of C/EBPβ and its role in inflammatory diseases.

IκBζ is an essential mediator of immunity to oropharyngeal candidiasis

Fungal infections are a global threat; yet, there are no licensed vaccines to any fungal pathogens. Th17 cells mediate immunity to Candida albicans, particularly oropharyngeal candidiasis (OPC), but essential downstream mechanisms remain unclear. In the murine model of OPC, IκBζ (Nfkbiz, a non-canonical NF-κB transcription factor) was upregulated in an interleukin (IL)-17-dependent manner and was essential to prevent candidiasis. Deletion of Nfkbiz rendered mice highly susceptible to OPC. IκBζ was dispensable in hematopoietic cells and acted partially in the suprabasal oral epithelium to control OPC. One prominent IκBζ-dependent gene target was β-defensin 3 (BD3) (Defb3), an essential antimicrobial peptide. Human oral epithelial cells required IκBζ for IL-17-mediated induction of BD2 (DEFB4A, human ortholog of mouse Defb3) through binding to the DEFB4A promoter. Unexpectedly, IκBζ regulated the transcription factor Egr3, which was essential for C. albicans induction of BD2/DEFB4A. Accordingly, IκBζ and Egr3 comprise an antifungal signaling hub mediating mucosal defense against oral candidiasis.

Soluble adenylyl cyclase contributes to imiquimod-mediated inflammation and is a potential therapeutic target in psoriasis

Cyclic AMP (cAMP) has a key role in psoriasis pathogenesis, as indicated by the therapeutic efficacy of phosphodiesterase inhibitors that prevent the degradation of cAMP. However, whether soluble adenylate cyclase (sAC) (encoded by the ADCY10 gene), which is an important source for cAMP, is involved in Th17 cell-mediated inflammation or could be an alternative therapeutic target in psoriasis is unknown. We have utilized the imiquimod model of murine psoriasiform dermatitis to address this question. Adcy10-/- mice had reduced erythema, scaling and swelling in the skin and reduced CD4+ IL17+ cell numbers in the draining lymph nodes, compared with wild-type mice after induction of psoriasiform dermatitis with imiquimod. Keratinocyte-specific knock out of Adcy10 had no effect on imiquimod-induced ear swelling suggesting keratinocyte sAC has no role in imiquimod-induced inflammation. During Th17 polarization in vitro, naive T cells from Adcy10-/- mice exhibited reduced IL17 secretion and IL-17+ T-cell proliferation suggesting that differentiation into Th17 cells is suppressed without sAC activity. Interestingly, loss of sAC did not impact the expression of Th17 lineage-defining transcription factors (such as Rorc and cMaf) but rather was required for CREB-dependent gene expression, which is known to support Th17 cell gene expression. Finally, topical application of small molecule sAC inhibitors (sACi) reduced imiquimod-induced psoriasiform dermatitis and Il17 gene expression in the skin. Collectively, these findings demonstrate that sAC is important for psoriasiform dermatitis in mouse skin. sACi may provide an alternative class of topical therapeutics for Th17-mediated skin diseases.

Single-Cell transcriptomes of immune cells provide insights into the therapeutic effects of mycophenolate mofetil on autoimmune uveitis

Mycophenolate mofetil (MMF) is an immunosuppressive agent widely applied in various autoimmune diseases, including autoimmune uveitis, a sight-threatening autoimmune disease mainly affecting the eyes. However, the mechanisms of action are not comprehensively understood. To investigate the potential impact of MMF on uveitis, we generated single-cell RNA sequence data from normal, experimental autoimmune uveitis (EAU) and MMF-treated EAU mice. We observed that some EAU-induced transcriptional changes were reversed by MMF treatment. Transcriptional data indicated that MMF may have a general inhibitory effect on the activation of immune cells during EAU. Each immune cell type showed a different response to MMF treatment. Pseudotime analysis showed that MMF treatment partly reversed the increased differentiation tendency from naïve to effector phenotypes of T and B cells in EAU. The reduced proportion of T-helper (Th)1 and T-helper (Th)17 cells after MMF treatment was confirmed using flow cytometry. MMF treatment downregulated the EAU-associated upregulation of several molecules (such as Cebpd, Pim1, Furin, Bhlhe40, and Hif1a) that promote pathogenic cytokine production by T helper (Th)-1 and Th17 cells. Abnormally enhanced immunoglobulin production, antigen processing, and presentation ability of B cells may also be inhibited by MMF treatment. In addition to T and B cells, MMF treatment countered EAU-induced transcriptional changes in other immune cells to different degrees. Overall, our findings provide novel insights into the mechanisms underlying MMF treatment and indicate that the therapeutic effect of MMF is not driven by a single molecule.

Caerin 1.1/1.9 Enhances Antitumour Immunity by Activating the IFN-α Response Signalling Pathway of Tumour Macrophages

Macrophages are one of the essential components of the tumour microenvironment (TME) of many cancers and show complex heterogeneity and functions. More recent research has been focusing on the characterisation of tumour-associated macrophages (TAMs). Previously, our study demonstrated that caerin 1.1/1.9 peptides significantly improve the therapeutic efficacy of combined specific immunotherapy and immune checkpoint blockade in a murine transplantable tumour model (TC-1). In this study, the mice inoculated with TC-1 tumour were immunised differently. The TAMs were isolated using flow cytometry and characterised by cytokine ELISA. The survival rates of mice with different treatments containing caerin 1.1/19 were assessed comparatively, including those with/without macrophage depletion. The single-cell RNA sequencing (scRNA-seq) data of previous studies were integrated to further reveal the functions of TAMs with the treatments containing caerin 1.1/1.9. As a comparison, the TAMs of stage I and II cervical cancer patients were analysed using scRNA-seq analysis. We demonstrate that caerin induced tumour clearance is associated with infiltration of tumours by IL-12 secreting Ly6C+F4/80+ macrophages exhibiting enhanced IFN-α response signalling, renders animals resistant to further tumour challenge, which is lost after macrophage depletion. Our results indicate that caerin 1.1/1.9 treatment has great potential in improving current immunotherapy efficacy.

Inhibition of PI3K/C/EBPβ axis in tolerogenic bone marrow-derived dendritic cells of NOD mice promotes Th17 differentiation and diabetes development

Dendritic cells (DCs) are key regulators of the adaptive immune response. Tolerogenic dendritic cells play a crucial role in inducing and maintaining immune tolerance in autoimmune diseases such as type 1 diabetes in humans as well as in the NOD mouse model. We previously reported that bone marrow-derived DCs (BM.DCs) from NOD mice, generated with a low dose of GM-CSF (GM/DCs), induce Treg differentiation and are able to protect NOD mice from diabetes. We had also found that the p38 MAPK/C/EBPβ axis is involved in regulating the phenotype, as well as the production of IL-10 and IL-12p70, by tolerogenic GM/DCs. Here, we report that the inhibition of the PI3K signaling switched the cytokine profile of GM/DCs toward Th17-promoting cytokines without affecting their phenotype. PI3K inhibition abrogated the production of IL-10 by GM/DCs, whereas it enhanced their production of IL-23 and TGFβ. Inhibition of PI3K signaling in tolerogenic GM/DCs also induced naive CD4⁺ T cells differentiation toward Th17 cells. Mechanistically, PI3K inhibition increased the DNA-binding activity of C/EBPβ through a GSK3-dependent pathway, which is important to maintain the semimature phenotype of tolerogenic GM/DCs. Furthermore, analysis of C/EBPβ^-/- GM/DCs demonstrated that C/EBPβ is required for IL-23 production. Of physiological relevance, the level of protection from diabetes following transfusion of GM/DCs into young NOD mice was significantly reduced when NOD mice were transfused with GM/DCs pretreated with a PI3K inhibitor. Our data suggest that PI3K/C/EBPβ signaling is important in controlling tolerogenic function of GM/DCs by limiting their Th17-promoting cytokines.

Epigenetic regulation of innate immune memory in microglia

Background

Microglia are the tissue-resident macrophages of the CNS. They originate in the yolk sac, colonize the CNS during embryonic development and form a self-sustaining population with limited turnover. A consequence of their relative slow turnover is that microglia can serve as a long-term memory for inflammatory or neurodegenerative events.

Methods

Using ATAC-, ChIP- and RNA-sequencing, we characterized the epigenomes and transcriptomes of FACS-purified microglia from mice exposed to different stimuli. A repeated endotoxin challenge (LPS) was used to induce tolerance in microglia, while genotoxic stress (DNA repair deficiency-induced accelerated aging through Ercc1 deficiency) resulted in primed (hypersensitive) microglia.

Results

Whereas the enrichment of permissive epigenetic marks at enhancer regions could explain training (hyper-responsiveness) of primed microglia to an LPS challenge, the tolerized response of microglia seems to be regulated by loss of permissive epigenetic marks. We identify that inflammatory stimuli and accelerated aging as a result of genotoxic stress activate distinct gene networks. These gene networks and associated biological processes are partially overlapping, which is likely driven by specific transcription factor networks, resulting in altered epigenetic signatures and distinct functional (desensitized vs. primed) microglia phenotypes.

Conclusion

This study provides insight into epigenetic profiles and transcription factor networks associated with transcriptional signatures of tolerized and trained microglia in vivo, leading to a better understanding of innate immune memory of microglia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02463-5.

T cell-intrinsic miR-155 is required for Th2 and Th17-biased responses in acute and chronic airway inflammation by targeting several different transcription factors

Asthmatic airway inflammation is divided into two typical endotypes: Th2-mediated eosinophilic and Th1- or Th17-mediated neutrophilic airway inflammation. The miRNA miR-155 has well-documented roles in the regulation of adaptive T-cell responses and innate immunity. However, no specific cell-intrinsic role has yet been elucidated for miR-155 in T cells in the course of Th2-eosinophilic and Th17-neutrophilic airway inflammation using actual in vivo asthma models. Here, using conditional KO (miR155^ΔCD4 cKO) mice that have the specific deficiency of miR-155 in T cells, we found that the specific deficiency of miR-155 in T cells resulted in fully suppressed Th2-type eosinophilic airway inflammation following acute allergen exposure, as well as greatly attenuated the Th17-type neutrophilic airway inflammation induced by repeated allergen exposure. Furthermore, miR-155 in T cells appeared to regulate the expression of several different target genes in the functional activation of CD4+ Th2 and Th17 cells. To be more precise, the deficiency of miR-155 in T cells enhanced the expression of c-Maf, SOCS1, Fosl2, and Jarid2 in the course of CD4+ Th2 cell activation, while C/EBPβ was highly enhanced in CD4+ Th17 cell activation in the absence of miR-155 expression. Conclusively, our data revealed that miR-155 could promote Th2 and Th17-mediated airway inflammation via the regulation of several different target genes, depending on the context of asthmatic diseases. Therefore, these results provide valuable insights in actual understanding of specific cell-intrinsic role of miR-155 in eosinophilic and neutrophilic airway inflammation for the development of fine-tune therapeutic strategies.

Identification of Regulatory Factors and Prognostic Markers in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of motor neurons, leading to muscle atrophy, paralysis and even death. Immune disorder, redox imbalance, autophagy disorder, and iron homeostasis disorder have been shown to play critical roles in the pathogenesis of ALS. However, the exact pathogenic genes and the underlying mechanism of ALS remain unclear. The purpose of this study was to screen for pathogenic regulatory genes and prognostic markers in ALS using bioinformatics methods. We used Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, gene set enrichment analysis (GSEA), and expression regulation network analysis to investigate the function of differentially expressed genes in the nerve tissue, lymphoid tissue, and whole blood of patients with ALS. Our results showed that the up-regulated genes were mainly involved in immune regulation and inflammation, and the down-regulated genes were mainly involved in energy metabolism and redox processes. Eleven up-regulated transcription factors (CEBPB, CEBPD, STAT5A, STAT6, RUNX1, REL, SMAD3, GABPB2, FOXO1, PAX6, and FOXJ1) and one down-regulated transcription factor (NOG) in the nerve tissue of patients with ALS likely play important regulatory roles in the pathogenesis of ALS. Based on construction and evaluation of the ALS biomarker screening model, cluster analysis of the identified characteristic genes, univariate Cox proportional hazards regression analysis, and the random survival forest algorithm, we found that MAEA, TPST1, IFNGR2, and ALAS2 may be prognostic markers regarding the survival of ALS patients. High expression of MAEA, TPST1, and IFNGR2 and low expression of ALAS2 in ALS patients may be closely related to short survival of ALS patients. Taken together, our results indicate that immune disorders, inflammation, energy metabolism, and redox imbalance may be the important pathogenic factors of ALS. CEBPB, CEBPD, STAT5A, STAT6, RUNX1, REL, SMAD3, GABPB2, FOXO1, PAX6, FOXJ1, and NOG may be important regulatory factors linked to the pathogenesis of ALS. MAEA, TPST1, IFNGR2, and ALAS2 are potential important ALS prognostic markers. Our findings provide evidence on the pathogenesis of ALS, potential targets for the development of new drugs for ALS, and important markers for predicting ALS prognosis.

Topical Application of Temperature-Sensitive Gel Containing Caerin 1.1 and 1.9 Peptides on TC-1 Tumour-Bearing Mice Induced High-Level Immune Response in the Tumour Microenvironment

The development of topical cream drugs that increase the immune activation of tumour-infiltrating lymphocytes against tumour and chronic viral infection-associated lesions is of great immunotherapeutic significance. This study demonstrates that the topical application of a temperature-sensitive gel containing caerin 1.1 and 1.9 peptides reduces nearly 50% of the tumour weight of HPV16 E6/E7-transformed TC-1 tumour-bearing mice via improving the tumour microenvironment. Confocal microscopy confirms the time-dependent penetration of caerin 1.9 through the epidermal layer of the ear skin structure of mice. Single-cell transcriptomic analysis shows that the caerin 1.1/1.9 gel expands the populations with high immune activation level and largely stimulates the pro-inflammatory activity of NK and dendritic cells. Closely associated with INFα response, Cebpb seems to play a key role in altering the function of all Arg1^hi macrophages in the caerin group. In addition, the caerin gel treatment recruits almost two-fold more activated CD8⁺ T cells to the TME, relative to the untreated tumour, which shows a synergistic effect derived from the regulation of S1pr1, Ccr7, Ms4a4b and Gimap family expression. The TMT10plex-labelling proteomic quantification further demonstrates the activation of interferon-alpha/beta secretion and response to cytokine stimulus by the caerin gel, while the protein contents of several key regulators were elevated by more than 30%, such as Cd5l, Gzma, Ifit1, Irf9 and Stat1. Computational integration of the proteome with the single-cell transcriptome consistently suggested greater activation of NK and T cells with the topical application of caerin peptide gel.

Multi-Omic Data Integration Allows Baseline Immune Signatures to Predict Hepatitis B Vaccine Response in a Small Cohort

Background

Vaccination remains one of the most effective means of reducing the burden of infectious diseases globally. Improving our understanding of the molecular basis for effective vaccine response is of paramount importance if we are to ensure the success of future vaccine development efforts.

Methods

We applied cutting edge multi-omics approaches to extensively characterize temporal molecular responses following vaccination with hepatitis B virus (HBV) vaccine. Data were integrated across cellular, epigenomic, transcriptomic, proteomic, and fecal microbiome profiles, and correlated to final HBV antibody titres.

Results

Using both an unsupervised molecular-interaction network integration method (NetworkAnalyst) and a data-driven integration approach (DIABLO), we uncovered baseline molecular patterns and pathways associated with more effective vaccine responses to HBV. Biological associations were unravelled, with signalling pathways such as JAK-STAT and interleukin signalling, Toll-like receptor cascades, interferon signalling, and Th17 cell differentiation emerging as important pre-vaccination modulators of response.

Conclusion

This study provides further evidence that baseline cellular and molecular characteristics of an individual's immune system influence vaccine responses, and highlights the utility of integrating information across many parallel molecular datasets.

A pathogenic and clonally expanded B cell transcriptome in active multiple sclerosis

B cells serve as a key weapon against infectious diseases. They also contribute to multiple autoimmune diseases, including multiple sclerosis (MS) where depletion of B cells is a highly effective therapy. We describe a comprehensive profile of central nervous system (CNS)-specific transcriptional B cell phenotypes in MS at single-cell resolution with paired immune repertoires. We reveal a polyclonal immunoglobulin M (IgM) and IgG1 cerebrospinal fluid B cell expansion polarized toward an inflammatory, memory and plasmablast/plasma cell phenotype, with differential up-regulation of specific proinflammatory pathways. We did not find evidence that CNS B cells harbor a neurotropic virus. These data support the targeting of activated resident B cells in the CNS as a potentially effective strategy for control of treatment-resistant chronic disease.

Central nervous system B cells have several potential roles in multiple sclerosis (MS): secretors of proinflammatory cytokines and chemokines, presenters of autoantigens to T cells, producers of pathogenic antibodies, and reservoirs for viruses that trigger demyelination. To interrogate these roles, single-cell RNA sequencing (scRNA-Seq) was performed on paired cerebrospinal fluid (CSF) and blood from subjects with relapsing-remitting MS (RRMS; n = 12), other neurologic diseases (ONDs; n = 1), and healthy controls (HCs; n = 3). Single-cell immunoglobulin sequencing (scIg-Seq) was performed on a subset of these subjects and additional RRMS (n = 4), clinically isolated syndrome (n = 2), and OND (n = 2) subjects. Further, paired CSF and blood B cell subsets (RRMS; n = 7) were isolated using fluorescence activated cell sorting for bulk RNA sequencing (RNA-Seq). Independent analyses across technologies demonstrated that nuclear factor kappa B (NF-κB) and cholesterol biosynthesis pathways were activated, and specific cytokine and chemokine receptors were up-regulated in CSF memory B cells. Further, SMAD/TGF-β1 signaling was down-regulated in CSF plasmablasts/plasma cells. Clonally expanded, somatically hypermutated IgM+ and IgG1+ CSF B cells were associated with inflammation, blood–brain barrier breakdown, and intrathecal Ig synthesis. While we identified memory B cells and plasmablast/plasma cells with highly similar Ig heavy-chain sequences across MS subjects, similarities were also identified with ONDs and HCs. No viral transcripts, including from Epstein–Barr virus, were detected. Our findings support the hypothesis that in MS, CSF B cells are driven to an inflammatory and clonally expanded memory and plasmablast/plasma cell phenotype.

Single-cell RNA-Seq reveals the transcriptional landscape and heterogeneity of skin macrophages in Vsir-/- murine psoriasis

Rationale: V-domain immunoglobulin suppressor of T cell activation (VISTA) is a novel inhibitory immune checkpoint molecule. Vsir^-/- mice have exacerbated psoriasis-like skin inflammation. The immune cell subsets involved in inflammation in Vsir^-/- psoriatic mice are largely unknown. We have used scRNA-seq as an unbiased profiling strategy to study the heterogeneity of immune cells at a single cell level in the skin of Vsir^-/- psoriatic mice.

Methods: In the present study, the right ear and shaved back skin of wild type and Vsir^-/- mice were treated with IMQ for 5 consecutive days to induce psoriasis-like dermatitis. Then, the single-cell RNA sequencing analysis of mouse back skin lesions was performed using 10 × Genomics technique.

Results: We identified 12 major cell subtypes among 23,258 cells. The major populations of the skin cells included macrophages, dendritic cells and fibroblasts. Macrophages constituted the main immune cell population in the WT (61.29%) and Vsir^-/- groups (77.7%). It should be noted that DCs and fibroblasts were expanded in the Vsir^-/- psoriatic mice. Furthermore, the gene expression signatures were assessed. We observed that Hspb1 and Cebpb were significantly upregulated in the Vsir^-/- psoriatic mice. Differential gene expression and gene ontology enrichment analyses revealed specific gene expression patterns distinguishing these subsets and uncovered putative functions of each cell type. Date analysis resulted in the discovery of a number of novel psoriasis-associated genes in Vsir^-/- mice.

Conclusion: We present a comprehensive single-cell landscape of the skin immune cells in Vsir^-/- psoriatic mice. These unprecedented data uncovered the transcriptional landscape and phenotypic heterogeneity of skin macrophages in psoriasis and identified their gene expression signature suggesting specialized functions in Vsir^-/- mice. Our findings will open novel opportunities to investigate the role of VISTA in driving psoriasis.

Ubiquitin Ligase COP1 Suppresses Neuroinflammation by Degrading c/EBPβ in Microglia

Dysregulated microglia are intimately involved in neurodegeneration, including Alzheimer's disease (AD) pathogenesis, but the mechanisms controlling pathogenic microglial gene expression remain poorly understood. The transcription factor CCAAT/enhancer binding protein beta (c/EBPβ) regulates pro-inflammatory genes in microglia and is upregulated in AD. We show expression of c/EBPβ in microglia is regulated post-translationally by the ubiquitin ligase COP1 (also called RFWD2). In the absence of COP1, c/EBPβ accumulates rapidly and drives a potent pro-inflammatory and neurodegeneration-related gene program, evidenced by increased neurotoxicity in microglia-neuronal co-cultures. Antibody blocking studies reveal that neurotoxicity is almost entirely attributable to complement. Remarkably, loss of a single allele of Cebpb prevented the pro-inflammatory phenotype. COP1-deficient microglia markedly accelerated tau-mediated neurodegeneration in a mouse model where activated microglia play a deleterious role. Thus, COP1 is an important suppressor of pathogenic c/EBPβ-dependent gene expression programs in microglia.

Key Vitamin D Target Genes with Functions in the Immune System

The biologically active form of vitamin D3, 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), modulates innate and adaptive immunity via genes regulated by the transcription factor vitamin D receptor (VDR). In order to identify the key vitamin D target genes involved in these processes, transcriptome-wide datasets were compared, which were obtained from a human monocytic cell line (THP-1) and peripheral blood mononuclear cells (PBMCs) treated in vitro by 1,25(OH)2D3, filtered using different approaches, as well as from PBMCs of individuals supplemented with a vitamin D3 bolus. The led to the genes ACVRL1, CAMP, CD14, CD93, CEBPB, FN1, MAPK13, NINJ1, LILRB4, LRRC25, SEMA6B, SRGN, THBD, THEMIS2 and TREM1. Public epigenome- and transcriptome-wide data from THP-1 cells were used to characterize these genes based on the level of their VDR-driven enhancers as well as the level of the dynamics of their mRNA production. Both types of datasets allowed the categorization of the vitamin D target genes into three groups according to their role in (i) acute response to infection, (ii) infection in general and (iii) autoimmunity. In conclusion, 15 genes were identified as major mediators of the action of vitamin D in innate and adaptive immunity and their individual functions are explained based on different gene regulatory scenarios.

microRNA-381-3p Confers Protection Against Ischemic Stroke Through Promoting Angiogenesis and Inhibiting Inflammation by Suppressing Cebpb and Map3k8

Ischemic stroke is a serious disease with limited prevention methods, and various genes and microRNAs (miRNAs) have been found to be dysregulated in the pathogenesis of this disease. This study aims to explore the potential role of miR-381-3p in ischemic stroke, along with its underlying mechanism. A mouse model of ischemic stroke was developed using middle cerebral artery occlusion. Next, the expression of mitogen-activated protein kinase kinase kinase 8 (Map3k8) and CCAAT enhancer binding protein beta (Cebpb) was determined by RT-qPCR. Gain- and loss-of-function approaches were applied to analyze the effects of miR-381-3p, Cebpb and Map3k8 on the biological functions of endothelial progenitor cells (EPCs) with the involvement of the tumor necrosis factor-α (TNF-α) signaling pathway. In addition, dual luciferase reporter gene assay was performed for the analysis of the relationship among miR-381-3p, Map3k8 and Cebpb. Further, rescue experiment was performed with the help of JNK/p38 specific agonist, Anisomycin. Map3k8 and Cebpb were highly expressed in ischemic stroke. Loss-of-function of Map3k8 or Cebpb in EPCs contributed to accelerated proliferation, migration and angiogenesis of EPCs. Next, miR-381-3p downregulated the expression of its two target genes, Map3k8 and Cebpb. miR-381-3p overexpression promoted angiogenesis of EPCs, and inhibited inflammation, which could be reversed by restoration of Map3k8 or Cebpb. Additionally, silencing Map3k8 or Cebpb inhibited the activation of TNF-α signaling pathway. Furthermore, Anisomycin treatment could enhance inflammation and inhibit angiogenesis. Taken together, miR-381-3p downregulates Map3k8 and Cebpb to protect against ischemic stroke, broadening our understanding of the pathogenesis of ischemic stroke.

Transcriptomic analysis of brain tissues identifies a role for CCAAT enhancer binding protein β in HIV-associated neurocognitive disorder

BACKGROUND

HIV-associated neurocognitive disorders (HAND) persist in the era of combined antiretroviral therapy (ART) despite reductions in viral load (VL) and overall disease severity. The mechanisms underlying HAND in the ART era are not well understood but are likely multifactorial, involving alterations in common pathways such as inflammation, autophagy, neurogenesis, and mitochondrial function. Newly developed omics approaches hold potential to identify mechanisms driving neuropathogenesis of HIV in the ART era.

METHODS

In this study, using 33 postmortem frontal cortex (FC) tissues, neuropathological, molecular, and biochemical analyses were used to determine cellular localization and validate expression levels of the prolific transcription factor (TF), CCAAT enhancer binding protein (C/EBP) β, in brain tissues from HIV+ cognitively normal and HAND cases. RNA sequencing (seq) and transcriptomic analyses were performed on FC tissues including 24 specimens from well-characterized people with HIV that had undergone neurocognitive assessments. In vitro models for brain cells were used to investigate the role of C/EBPβ in mediating gene expression.

RESULTS

The most robust signal for TF dysregulation was observed in cases diagnosed with minor neurocognitive disorder (MND) compared to cognitive normal (CN) cases. Of particular interest, due to its role in inflammation, autophagy and neurogenesis, C/EBPβ was significantly upregulated in MND compared to CN brains. C/EBPβ was increased at the protein level in HAND brains. C/EBPβ levels were significantly reduced in neurons and increased in astroglia in HAND brains compared to CN. Transfection of human astroglial cells with a plasmid expressing C/EBPβ induced expression of multiple targets identified in the transcriptomic analysis of HAND brains, including dynamin-1-like protein (DNM1L) and interleukin-1 receptor-associated kinase 1. Recombinant HIV-Tat reduced and increased C/EBPβ levels in neuronal and astroglial cells, respectively.

CONCLUSIONS

These findings are the first to present RNAseq-based transcriptomic analyses of HIV+ brain tissues, providing further evidence of altered neuroinflammation, neurogenesis, mitochondrial function, and autophagy in HAND. Interestingly, these studies confirm a role for CEBPβ in regulating inflammation, metabolism, and autophagy in astroglia. Therapeutic strategies aimed at transcriptional regulation of astroglia or downstream pathways may provide relief to HIV+ patients at risk for HAND and other neurological disorders.

C/EBPß Isoform Specific Gene Regulation: It's a Lot more Complicated than you Think!

It has been almost 30 years since C/EBPß was discovered. Seminal studies have shown that C/EBPß is a master regulator of mammary gland development and has been shown to control and influence proliferation and differentiation through varying mechanisms. The single-exon C/EBPß mRNA yields at least three different protein isoforms which have diverse, specific, context-dependent, and often non-overlapping roles throughout development and breast cancer progression. These roles are dictated by a number of complex factors including: expression levels of other C/EBP family members and their stoichiometry relative to the isoform in question, binding site affinity, post-translational modifications, co-factor expression, and even hormone levels and lactogenic status. Here we summarize the historical work up to the latest findings in the field on C/EBPß in the mammary gland and in breast cancer. With the current emphasis on improving immunotherapy in breast cancer the role of specific C/EBPß isoforms in regulating specific chemokine and cytokine expression and the immune microenvironment will be of increasing interest.

Gene discovery for high-density lipoprotein cholesterol level change over time in prospective family studies

BACKGROUNDS AND AIMS

Several genes are known to contribute to the levels and metabolism of HDL-C, however, their protective effects in cardiovascular disease (CVD), healthy aging, and longevity are complex and poorly understood. It is also unclear if these genes predict longitudinal HDL-C change. We aimed to identify loci influencing HDL-C change.

METHODS

We performed a genome-wide association study (GWAS) with harmonized HDL-C and imputed genotype in three family-based studies recruited for exceptional survival (Long Life Family Study), from community-based (Framingham Heart Study) and enriched for CVD (Family Heart Study). In 7738 individuals with at least 2 visits, we employed a growth curve model to estimate the random linear trajectory parameter of age-sex-adjusted HDL-C for each person. GWAS was performed using a linear regression model on HDL-C change accounting for kinship correlations, population structure, and differences among studies.

RESULTS

We identified a novel association for HDL-C with GRID1 (p = 5.43 × 10^-10), which encodes a glutamate receptor channel subunit involved in synaptic plasticity. Seven suggestive novel loci (p < 1.0 × 10^-6; MBOAT2, LINC01876-NR4A2, NTNG2, CYSLTR2, SYNE2, CTXND1-LINC01314, and CYYR1) and a known lipid gene (ABCA10) showed associations with HDL-C change. Two additional sex-specific suggestive loci were identified in women (DCLK2 and KCNJ2). Several of these genetic variants are associated with lipid-related conditions influencing cardiovascular and metabolic health, have predictive regulatory function, and are involved in lipid-related pathways.

CONCLUSIONS

Modeling longitudinal HDL-C in prospective studies, with differences in healthy aging, longevity and CVD risk, contributed to gene discovery and provided insights into mechanisms of HDL-C regulation.

Analysis of microRNA expression profiles in porcine PBMCs after LPS stimulation

In the present study, we used microRNA (miRNA) sequencing to discover and explore the expression profiles of known and novel miRNAs in 1000 ng/ml LPS stimulated for 8 h vis-à-vis non-stimulated (i.e. control) PBMCs isolated from the blood of healthy pigs. A total of 291 known miRNAs were bio-computationally identified in porcine PBMCs, and 228 novel miRNAs (not enlisted in the swine mirBase) were identified. Among these miRNAs, ssc-miR-148a-3p, ssc-let-7g, ssc-let-7f, 3_8760, ssc-miR-26a, ssc-miR-451, ssc-miR-21, ssc-miR-30d, ssc-miR-99a and ssc-miR-103 were the top 10 most abundant miRNAs in porcine PBMCs. Through miRNA differential analysis combined with quantitative PCR, we found the expressions of ssc-miR-122, ssc-miR-129b, ssc-miR-17-5p and ssc-miR-152 were significantly changed in porcine PBMCs after LPS stimulation. Furthermore, targets prediction and function analysis indicated a significant enrichment in gene ontology functional categories related to diseases, immunity and inflammation. In conclusion, this study on profiling of miRNAs expressed in LPS-stimulated PBMCs provides an important reference point for future studies on regulatory roles of miRNAs in porcine immune system.

Dietary fish oil supplementation alters liver gene expressions to protect against LPS-induced liver injury in weanling piglets

Here, the potential mechanisms of the protective effects of fish oil against LPS-induced liver injury in a piglet model were investigated by using RNA sequencing. Twenty-four piglets were used in a 2 × 2 factorial design, and the main factors included diet (5% corn oil or 5% fish oil) and immunological challenge (LPS or saline, on d 19). All piglets were slaughtered at 4 h after challenge, and liver samples were collected. Fish oil improved liver morphology and reduced TNF-α, IL-1β and IL-6 productions after LPS challenge. RNA sequencing analysis showed fish oil had significant effect on the expressions of genes involved in immune response during LPS-induced inflammation. Selected gene expression changes were validated using quantitative RT-PCR. Fish oil reduced the expressions of pro-inflammatory genes IL1R1, IL1RAP, CEBPB and CRP, and increased that of anti-inflammatory genes IL-18BP, NFKBIA, IFIT1, IFIT2 and ATF3. Moreover, fish oil restored the expressions of some lipid metabolism-related genes, such as ACAA1, ACACA, ACADS and ACADM, which were only decreased in pigs fed a corn oil diet after LPS challenge. Our RNA sequencing reveals novel gene-nutrient interactions following fish oil supplementation and evoked inflammation, which add to the current understanding of the benefits of n-3 polyunsaturated fatty acids against liver injury.

Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Induces Interleukin-17 Production via Activation of the IRAK1-PI3K-p38MAPK-C/EBPβ/CREB Pathways

Porcine reproductive and respiratory syndrome virus (PRRSV) is widely prevalent in pigs, resulting in significant economic losses worldwide. A compelling impact of PRRSV infection is severe pneumonia. In the present study, we found that interleukin-17 (IL-17) was upregulated by PRRSV infection. Subsequently, we demonstrated that PI3K and p38MAPK signaling pathways were essential for PRRSV-induced IL-17 production as addition of phosphatidylinositol 3-kinase (PI3K) and p38MAPK inhibitors dramatically reduced IL-17 production. Furthermore, we show here that deleting the C/EBPβ and CREB binding motif in porcine IL-17 promoter abrogated its activation and that knockdown of C/EBPβ and CREB remarkably impaired PRRSV-induced IL-17 production, suggesting that IL-17 expression was dependent on C/EBPβ and CREB. More specifically, we demonstrate that PRRSV nonstructural protein 11 (nsp11) induced IL-17 production, which was also dependent on PI3K-p38MAPK-C/EBPβ/CREB pathways. We then show that Ser74 and Phe76 amino acids were essential for nsp11 to induce IL-17 production and viral rescue. In addition, IRAK1 was required for nsp11 to activate PI3K and enhance IL-17 expression by interacting with each other. Importantly, we demonstrate that PI3K inhibitor significantly suppressed IL-17 production and lung inflammation caused by HP-PRRSV in vivo, implicating that higher IL-17 level induced by HP-PRRSV might be associated with severe lung inflammation. These findings provide new insights onto the molecular mechanisms of the PRRSV-induced IL-17 production and help us further understand the pathogenesis of PRRSV infection.IMPORTANCE Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) associated with severe pneumonia has been one of the most important viral pathogens in pigs. IL-17 is a proinflammatory cytokine that might be associated with the strong inflammation caused by PRRSV. Therefore, we sought to determine whether PRRSV infection affects IL-17 expression, and if so, determine this might partially explain the underlying mechanisms for the strong inflammation in HP-PRRSV-infected pigs, especially in lungs. Here, we show that PRRSV significantly induced IL-17 expression, and we subsequently dissected the molecular mechanisms about how PRRSV regulated IL-17 production. Furthermore, we show that Ser74 and Phe76 in nsp11 were indispensable for IL-17 production and viral replication. Importantly, we demonstrated that PI3K inhibitor impaired IL-17 production and alleviated lung inflammation caused by HP-PRRSV infection. Our findings will help us for a better understanding of PRRSV pathogenesis.

Immune Control by TRAF6-Mediated Pathways of Epithelial Cells in the EIME (Epithelial Immune Microenvironment)

In the protective responses of epithelial tissues, not only immune cells but also non-immune cells directly respond to external agents. Epithelial cells can be involved in the organization of immune responses through two phases. First, the exogenous harmful agents trigger the primary responses of the epithelial cells leading to various types of immune cell activation. Second, cytokines produced by the immune cells that are activated directly by the external agents and indirectly by the epithelial cell products elicit the secondary responses giving rise to further propagation of immune responses. TRAF6 is a ubiquitin E3 ligase, which intermediates between various types of receptors for exogenous agents or endogenous mediators and activation of subsequent transcriptional responses via NF-kappaB and MAPK pathways. TRAF6 ubiquitously participates in many protective responses in immune and non-immune cells. Particularly, epithelial TRAF6 has an essential role in the primary and secondary responses via driving type 17 response in psoriatic inflammation of the skin. Consistently, many psoriasis susceptibility genes encode the TRAF6 signaling players, such as ACT1 (TRAF3IP2), A20 (TNFAIP3), ABIN1 (TNIP1), IL-36Ra (IL36RN), IkappaBzeta (NFKBIZ), and CARD14. Herein, we describe the principal functions of TRAF6, especially in terms of positive and regulatory immune controls by interaction between immune cells and epithelial cells. In addition, we discuss how TRAF6 in the epithelial cells can organize the differentiation of immune responses and drive inflammatory loops in the epithelial immune microenvironment, which is termed EIME.

Epigenetics, DNA Organization, and Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders affecting the gastrointestinal tract. The incidence of IBD is increasing, with more cases occurring in developed countries. Multiple factors such as genetics, environmental changes, gut microbiota, and immune abnormalities have been associated with development of IBD. In recent years, it has become increasingly apparent that epigenetic modifications of chromatin and the manner in which chromatin is organized in the nucleus are additionally important elements that can influence responses induced by the factors described above, and may therefore contribute to the onset and pathogenesis of IBD. Epigenetics and chromatin organization regulate diverse functions that include maintenance of homeostasis in the intestinal epithelium, the development and differentiation of immune cells, and modulation of responses generated by the immune system to defend against potential pathogens. Furthermore, changes in epigenetic chromatin marks and in chromatin organization have now been linked to differential gene expression in IBD patient cells. Although direct evidence for a role of histone modifications in IBD is currently very limited, in this review, we summarize the links between various epigenetic modifications, the proteins that catalyze or recognize these modifications, and the development or progression of IBD in human and experimental IBD. We also discuss how epigenetics influence the organization of DNA contacts to regulate gene expression and the implications this may have for diagnosing and treating IBD.

Early Growth Response Gene-2 Is Essential for M1 and M2 Macrophage Activation and Plasticity by Modulation of the Transcription Factor CEBPβ

The process of macrophage polarization is involved in many pathologies such as anti-cancer immunity and autoimmune diseases. Polarized macrophages exhibit various levels of plasticity when M2/M(IL-4) macrophages are reprogrammed into an M1-like phenotype following treatment with IFNγ and/or LPS. At the same time, M1 macrophages are resistant to reprogramming in the presence of M2-like stimuli. The molecular mechanisms responsible for the macrophages polarization, plasticity of M2 macrophages, and lack of plasticity in M1 macrophages remain unknown. Here, we explored the role of Egr2 in the induction and maintenance of macrophage M1 and M2 polarization in the mouse in vitro and in vivo models of inflammation. Egr2 knockdown with siRNA treatment fail to upregulate either M1 or M2 markers upon stimulation, and the overexpression of Egr2 potentiated M1 or M2 marker expression following polarization. Polarisation with M2-like stimuli (IL-4 or IL-13) results in increased Egr2 expression, but macrophages stimulated with M1-like stimuli (IFNγ, LPS, IL-6, or TNF) exhibit a decrease in Egr2 expression. Egr2 was critical for the expression of transcription factors CEBPβ and PPARγ in M2 macrophages, and CEBPβ was highly expressed in M1-polarized macrophages. In siRNA knockdown studies the transcription factor CEBPβ was found to negatively regulate Egr2 expression and is likely to be responsible for the maintenance of the M1-like phenotype and lack plasticity. During thioglycolate-induced peritonitis, adoptively transferred macrophages with Egr2 knockdown failed to become activated as determined by upregulation of MHC class II and CD86. Thus, our study indicates that Egr2 expression is associated with the ability of unstimulated or M2 macrophages to respond to stimulation with inflammatory stimuli, while low levels of Egr2 expression is associated with non-responsiveness of macrophages to their activation.