Runx3 regulates mouse TGF-beta-mediated dendritic cell function and its absence results in airway inflammation

Identification of common genetic factors and immune-related pathways associating more than two autoimmune disorders: implications on risk, diagnosis, and treatment

Autoimmune disorders (ADs) are chronic conditions resulting from failure or breakdown of immunological tolerance, resulting in the host immune system attacking its cells or tissues. Recent studies report shared effects, mechanisms, and evolutionary origins among ADs; however, the possible factors connecting them are unknown. This study attempts to identify gene signatures commonly shared between different autoimmune disorders and elucidate their molecular pathways linking the pathogenesis of these ADs using an integrated gene expression approach. We employed differential gene expression analysis across 19 datasets of whole blood/peripheral blood cell samples with five different autoimmune disorders (rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, Crohn's disease, and type 1 diabetes) to get nine key genes-EGR1, RUNX3, SMAD7, NAMPT, S100A9, S100A8, CYBB, GATA2, and MCEMP1 that were primarily involved in cell and leukocyte activation, leukocyte mediated immunity, IL-17, AGE-RAGE signaling in diabetic complications, prion disease, and NOD-like receptor signaling confirming its role in immune-related pathways. Combined with biological interpretations such as gene ontology (GO), pathway enrichment, and protein-protein interaction (PPI) network, our current study sheds light on the in-depth research on early detection, diagnosis, and prognosis of different ADs.

The bacterial lysate OM-85 engages Toll-like receptors 2 and 4 triggering an immunomodulatory gene signature in human myeloid cells

OM-85 is a bacterial lysate used in clinical practice to reduce duration and frequency of recurrent respiratory tract infections. Whereas knowledge of its regulatory effects in vivo has substantially advanced, the mechanisms of OM-85 sensing remain inadequately addressed. Here, we show that the immune response to OM-85 in the mouse is largely mediated by myeloid immune cells through Toll-like receptor (TLR) 4 in vitro and in vivo. Instead, in human immune cells, TLR2 and TLR4 orchestrate the response to OM-85, which binds to both receptors as shown by surface plasmon resonance assay. Ribonucleic acid-sequencing analyses of human monocyte-derived dendritic cells reveal that OM-85 triggers a pro-inflammatory signature and a unique gene set, which is not induced by canonical agonists of TLR2 or TLR4 and comprises tolerogenic genes. A largely overlapping TLR2/4-dependent gene signature was observed in individual subsets of primary human airway myeloid cells, highlighting the robust effects of OM-85. Collectively, our results suggest caution should be taken when relating murine studies on bacterial lysates to humans. Furthermore, our data shed light on how a standardized bacterial lysate shapes the response through TLR2 and TLR4, which are crucial for immune response, trained immunity, and tolerance.

Young SINEs in pig genomes impact gene regulation, genetic diversity, and complex traits

Transposable elements (TEs) are a major source of genetic polymorphisms and play a role in chromatin architecture, gene regulatory networks, and genomic evolution. However, their functional role in pigs and contributions to complex traits are largely unknown. We created a catalog of TEs (n = 3,087,929) in pigs and found that young SINEs were predominantly silenced by histone modifications, DNA methylation, and decreased accessibility. However, some transcripts from active young SINEs showed high tissue-specificity, as confirmed by analyzing 3570 RNA-seq samples. We also detected 211,067 dimorphic SINEs in 374 individuals, including 340 population-specific ones associated with local adaptation. Mapping these dimorphic SINEs to genome-wide associations of 97 complex traits in pigs, we found 54 candidate genes (e.g., ANK2 and VRTN) that might be mediated by TEs. Our findings highlight the important roles of young SINEs and provide a supplement for genotype-to-phenotype associations and modern breeding in pigs.

Epigenetic reprogramming of Runx3 reinforces CD8 + T-cell function and improves the clinical response to immunotherapy

BACKGROUND

Checkpoint blockade immunotherapy, represented by PD-1 or PD-L1 antibody treatment, has been of tremendous success in clinical practice. However, the low clinical response rate and lack of biomarkers for prediction of the immune response limit the clinical application of anti-PD-1 immunotherapy. Our recent work showed that a combination of low-dose decitabine and PD-1-ab significantly improved the complete response (CR) rate of cHL patients from 32 to 71%, which indicates that there is a significant correlation between epigenetic regulation and the clinical response to immunotherapy.

METHODS

We recruited two groups of Hodgkin lymphoma patients who were treated with anti-PD-1 and DAC+anti-PD-1. CD8+ T cells were isolated from the patients' peripheral blood, DNA methylation was analyzed by EPIC, the expression profile was analyzed by RNA-seq, and multigroup analysis was performed with IPA and GSEA functional annotations. We explored the effect of DAC on the function of CD8+ T cells in the blood, spleen, tumor and lymph nodes using a mouse model. Furthermore, we explored the function of Tils in the tumor microenvironment. Then, we constructed Runx3-knockout mice to confirm the T-cell-specific function of Runx3 in CD8+ T cells and analyzed various subtypes of T cells and cytokines using mass cytometry (CyTOF).

RESULTS

Multiomics analysis identified that DNA methylation reprogramming of Runx3 was a crucial mediator of CD8+ T-cell function. Multiomics data showed that reversal of methylation of the Runx3 promoter promoted the infiltration of CD8+ TILs and mitigated the exhaustion of CD8+ T cells. Furthermore, experiments on tissue-specific Runx3-knockout mice showed that Runx3 deficiency reduced CD8+ T infiltration and the differentiation of effector T and memory T cells. Furthermore, Runx3 deficiency significantly decreased CCR3 and CCR5 levels. Immunotherapy experiments in Runx3 conditional knockout mice showed that DAC could not reverse the resistance of anti-PD-1 in the absence of Runx3. Moreover, both our clinical data and data from TISIDB showed that Runx3 could be a potential biomarker for immunotherapy to predict the clinical response rate.

CONCLUSION

We demonstrate that the DNA methylation of Runx3 plays a critical role in CD8+ T-cell infiltration and differentiation during decitabine-primed PD-1-ab immunotherapy, which provides a supporting mechanism for the essential role of epiregulation in immunotherapy.

Skin barrier immunology from early life to adulthood

Our skin has a unique barrier function, which is imperative for the body's protection against external pathogens and environmental insults. Although interacting closely and sharing many similarities with key mucosal barrier sites, such as the gut and the lung, the skin also provides protection for internal tissues and organs and has a distinct lipid and chemical composition. Skin immunity develops over time and is influenced by a multiplicity of different factors, including lifestyle, genetics, and environmental exposures. Alterations in early life skin immune and structural development may have long-term consequences for skin health. In this review, we summarize the current knowledge on cutaneous barrier and immune development from early life to adulthood, with an overview of skin physiology and immune responses. We specifically highlight the influence of the skin microenvironment and other host intrinsic, host extrinsic (e.g. skin microbiome), and environmental factors on early life cutaneous immunity.

A novel 3D cell culture model to study the human small intestinal immune landscape

Several subsets of mononuclear phagocytes and DCs (MDC) populate the small intestine (SI), and these cells reportedly exert specialized functions in anti-microbial immunity and tolerance. Given the specialized phenotype of these cells, differing from other MDC family members, including their putative circulating blood precursors, local intestinal factors play key instructive roles in their differentiation. We designed an SI cell culture model composed of three intestinal epithelial cell (IEC) types, including absorptive enterocytes (E cells), antigen delivering microfold (M) cells, and mucus-producing goblet (G) cells plus T lymphocytes and soluble B cell-derived factors. This model was used to study the differentiation fate of CD34⁺ hematopoietic progenitor cell-derived monocyte/DC precursors. Progeny cells can be analyzed after a 3-week co-culture period, mimicking the physiologic turn-over time of intestinal MDC. A dominant monocyte differentiation pathway was suppressed, in favor of partial differentiation along DC and macrophage pathways, with low percentages of cells acquired DC or macrophage markers. Moreover, E and G cells play opposing roles in CX3CR1⁺ vs CD103^dim cell differentiation, indicating that both together might counter-balance M/DC differentiation. Thus, SI epithelial cells suppress M/DC differentiation, supporting a key role for exogenous factors in M/DC differentiation.

The RUNX/CBFβ Complex in Breast Cancer: A Conundrum of Context

Dissecting and identifying the major actors and pathways in the genesis, progression and aggressive advancement of breast cancer is challenging, in part because neoplasms arising in this tissue represent distinct diseases and in part because the tumors themselves evolve. This review attempts to illustrate the complexity of this mutational landscape as it pertains to the RUNX genes and their transcription co-factor CBFβ. Large-scale genomic studies that characterize genetic alterations across a disease subtype are a useful starting point and as such have identified recurring alterations in CBFB and in the RUNX genes (particularly RUNX1). Intriguingly, the functional output of these mutations is often context dependent with regards to the estrogen receptor (ER) status of the breast cancer. Therefore, such studies need to be integrated with an in-depth understanding of both the normal and corrupted function in mammary cells to begin to tease out how loss or gain of function can alter the cell phenotype and contribute to disease progression. We review how alterations to RUNX/CBFβ function contextually ascribe to breast cancer subtypes and discuss how the in vitro analyses and mouse model systems have contributed to our current understanding of these proteins in the pathogenesis of this complex set of diseases.

CD109 on Dendritic Cells Regulates Airway Hyperreactivity and Eosinophilic Airway Inflammation

Asthma is a chronic airway inflammatory disease characterized by airway hyperreactivity (AHR) and eosinophilic airway inflammation. Dendritic cells (DCs) are essential for the development of asthma via presenting allergens, causing T-helper cell type 2 (Th2) skewing and eosinophil inflammation. Recent studies have revealed that CD109, a glycosylphosphatidylinositol-anchored glycoprotein, is involved in the pathogenesis of inflammatory diseases such as rheumatoid arthritis and psoriasis. However, no study has addressed the role of CD109 in asthma. This study sought to address the role of CD109 on DCs in the development of AHR and allergic inflammation. CD109-deficient mice (CD109^-/-) were sensitized with house dust mite or ovalbumin and compared with wild-type mice for induction of AHR and allergic inflammation. CD109-deficient mice had reduced AHR and eosinophilic inflammation together with lower Th2 cytokine expression compared with wild-type mice. Interestingly, CD109 expression was induced in lung conventional DC2s (cDC2s), but not lung cDC1s, upon allergic challenge. Lung cDC2s from CD109^-/- mice had a poor ability to induce cytokine production in ex vivo DC-T cell cocultures with high expression of RUNX3 (runt-related transcription factor 3), resulting in suppression of Th2 differentiation. Adoptive transfer of bone marrow-derived CD109^-/- DCs loaded with house dust mite failed to develop AHR and eosinophilic inflammation. Finally, administration of monoclonal anti-CD109 antibody reduced airway eosinophils and significantly decreased AHR. Our results suggest the involvement of CD109 in asthma pathogenesis. CD109 is a novel therapeutic target for asthma.

MicroRNA-19a Inhibition Directly and Indirectly Ameliorates Th2 Airway Inflammation in Asthma by Targeting RUNX3

Disruption of T-cell differentiation is characteristic of airway inflammation in allergic asthma. How miR-19a works in asthma has not been completely elucidated. This study aimed to examine whether microRNA-19a regulates helper T-cell proliferation and to identify the factors involved and the underlying mechanisms. Our results showed that miR-19a levels were upregulated in parallel with a reduction in RUNX3 expression in a house dust mite (HDM)-induced murine model of asthma. A dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay showed that RUNX3 was a direct target of miR-19a. Inhibiting the expression of miR-19a attenuated inflammation and mucus production, induced Th1 cells, suppressed the Th2 inflammatory response, and repressed dendritic cell (DC) maturation by increasing RUNX3 expression in WT asthmatic mice but not RUNX3^+/- mice. In vitro experiments revealed that miR-19a inhibition could target RUNX3 to induce Th1 polarization and inhibit Th2 polarization by directly acting on naïve CD4⁺ T cells or indirectly mediating the maturation and antigen-presenting abilities of DCs. These findings indicate that miR-19a directly and indirectly regulates immunoinflammatory responses in asthma by targeting RUNX3.

Single-cell analysis of myeloid cells in HPV+ tonsillar cancer

The incidence of human papillomavirus-positive (HPV⁺) tonsillar cancer has been sharply rising during the last decades. Myeloid cells represent an appropriate therapeutic target due to their proximity to virus-infected tumor cells, and their ability to orchestrate antigen-specific immunity, within the tonsil. However, the interrelationship of steady-state and inflammatory myeloid cell subsets, and their impact on patient survival remains unexplored. Here, we used single-cell RNA-sequencing to map the myeloid compartment in HPV⁺ tonsillar cancer. We observed an expansion of the myeloid compartment in HPV⁺ tonsillar cancer, accompanied by interferon-induced cellular responses both in dendritic cells (DCs) and monocyte-macrophages. Our analysis unveiled the existence of four DC lineages, two macrophage polarization processes, and their sequential maturation profiles. Within the DC lineages, we described a balance shift in the frequency of progenitor and mature cDC favoring the cDC1 lineage in detriment of cDC2s. Furthermore, we observed that all DC lineages apart from DC5s matured into a common activated DC transcriptional program involving upregulation of interferon-inducible genes. In turn, the monocyte-macrophage lineage was subjected to early monocyte polarization events, which give rise to either interferon-activated or CXCL-producing macrophages, the latter enriched in advanced tumor stages. We validated the existence of most of the single-cell RNA-seq clusters using 26-plex flow cytometry, and described a positive impact of cDC1 and interferon-activated DCs and macrophages on patient survival using gene signature scoring. The current study contributes to the understanding of myeloid ontogeny and dynamics in HPV-driven tonsillar cancer, and highlights myeloid biomarkers that can be used to assess patient prognosis.

Resident macrophages of the lung and liver: The guardians of our tissues

Resident macrophages play a unique role in the maintenance of tissue function. As phagocytes, they are an essential first line defenders against pathogens and much of the initial characterization of these cells was focused on their interaction with viral and bacterial pathogens. However, these cells are increasingly recognized as contributing to more than just host defense. Through cytokine production, receptor engagement and gap junction communication resident macrophages tune tissue inflammatory tone, influence adaptive immune cell phenotype and regulate tissue structure and function. This review highlights resident macrophages in the liver and lung as they hold unique roles in the maintenance of the interface between the circulatory system and the external environment. As such, we detail the developmental origin of these cells, their contribution to host defense and the array of tools these cells use to regulate tissue homeostasis.

Inducible general knockout of Runx3 profoundly reduces pulmonary cytotoxic CD8+ T cells with minimal effect on outcomes in mice following influenza infection

Respiratory viruses pose a continuing and substantive threat to human health globally. Host innate and adaptive immune responses are the critical antiviral defense mechanisms to control viral replication and spread. The present study is designed to determine the role of transcription factor Runx3 in the host immune response to influenza A virus (IAV) infection. As Runx3 is required for embryonic development, we generated an inducible Runx3 global knockout (KO) mouse model and found that Runx3 KO in adult C57BL/6 mice minimally affected thymic function under normal conditions and survival was at least 250 days post Runx3 deletion. We applied the mouse model to IAV infection and found that Runx3 KO resulted in a huge reduction (>85%) in numbers of total and antigen-specific pulmonary CD8⁺ cytotoxic T cells during IAV infection, while it had a minor effect on pulmonary generation of CD4⁺ T cells. To our surprise, this general KO of Runx3 did not significantly alter viral clearance and animal survival following IAV infection. Interestingly, we found that Runx3 KO significantly increased the numbers of pulmonary innate immune cells such as macrophages and neutrophils and the production of pro-inflammatory cytokines during IAV infection. We further found that Runx3 was strongly detected in CCR2⁺ immune cells in IAV-infected mouse lungs and was induced in activated macrophages and dendritic cells (DCs). As pulmonary CD8⁺ cytotoxic T cells play a central role in the clearance of IAV, our findings suggest that Runx3 KO may enhance host innate immunity to compensate for the loss of pulmonary CD8⁺ cytotoxic T cells during IAV infection.

RUNX regulated immune-associated genes predicts prognosis in breast cancer

Background: Breast cancer is the most common malignant tumor in women. RUNX family has been involved in the regulation of different carcinogenic processes and signaling pathways with cancer, which is closely related to immunity and prognosis of various tumors, and also plays an important role in the development and prognosis of breast cancer.

Methods: We discovered the expression of RUNX family through GEPIA Dataset and then evaluated the relationship between RUNX family and immune-related genes and the prognosis of breast cancer through analyzing TCGA database. A prognostic model was established and verified via cox proportional hazards regression model using R packages. We evaluated the accuracy of the prognostic model by Kaplan-Meier curves and receiver operating characteristic (ROC) curves. Additionally, we obtained the relationship between the RUNX family and immune infiltration by TIMER database. Finally, the dual luciferase reporter assay was used to verify the regulation of RUNX3 on potential target genes ULBP2 and TRDV1, and the effects of ULBP2 and TRDV1 on the growth of breast cancer cells were explored by CCK-8, colony formation and wound healing assays.

Results: We screened out RUNX family-regulated immune-related genes associated with the prognosis of breast cancer. These predictors included PSME2, ULBP2, IL-18, TSLP, NPR3, TRDV1. Then a prognosis-related risk score model was built using the independent risk factors to provide a clinically appropriate method predicting the overall survival (OS) probability of the patients with breast cancer. In addition, a further research was made on the functions of high risk immune gene ULBP2 and low risk immune gene TRDV1 which regulated by RUNX3, the results showed that down-regulation of ULBP2 suppressed breast cancer cell proliferation and TRDV1 had the opposite functions. The prognostic model we constructed could promote the development of prognostic, and was associated with lower immune infiltration.

Conclusion: The expression of RUNX family was closely related to the prognosis of breast cancer. At the same time, RUNX family could modulate the functions of immune-related genes, and affect the development and prognosis of breast cancer. These immune-related genes regulated by RUNX family could be promising prognostic biomarkers and therapeutic targets in breast cancer.

Increased expression of RUNX3 inhibits normal human myeloid development

RUNX3 is a transcription factor dysregulated in acute myeloid leukemia (AML). However, its role in normal myeloid development and leukemia is poorly understood. Here we investigate RUNX3 expression in both settings and the impact of its dysregulation on myelopoiesis. We found that RUNX3 mRNA expression was stable during hematopoiesis but decreased with granulocytic differentiation. In AML, RUNX3 mRNA was overexpressed in many disease subtypes, but downregulated in AML with core binding factor abnormalities, such as RUNX1::ETO. Overexpression of RUNX3 in human hematopoietic stem and progenitor cells (HSPC) inhibited myeloid differentiation, particularly of the granulocytic lineage. Proliferation and myeloid colony formation were also inhibited. Conversely, RUNX3 knockdown did not impact the myeloid growth and development of human HSPC. Overexpression of RUNX3 in the context of RUNX1::ETO did not rescue the RUNX1::ETO-mediated block in differentiation. RNA-sequencing showed that RUNX3 overexpression downregulates key developmental genes, such as KIT and RUNX1, while upregulating lymphoid genes, such as KLRB1 and TBX21. Overall, these data show that increased RUNX3 expression observed in AML could contribute to the developmental arrest characteristic of this disease, possibly by driving a competing transcriptional program favoring a lymphoid fate.

An Experimental Model of Neuro-Immune Interactions in the Eye: Corneal Sensory Nerves and Resident Dendritic Cells

The cornea is an avascular connective tissue that is crucial, not only as the primary barrier of the eye but also as a proper transparent refractive structure. Corneal transparency is necessary for vision and is the result of several factors, including its highly organized structure, the physiology of its few cellular components, the lack of myelinated nerves (although it is extremely innervated), the tightly controlled hydration state, and the absence of blood and lymphatic vessels in healthy conditions, among others. The avascular, immune-privileged tissue of the cornea is an ideal model to study the interactions between its well-characterized and dense sensory nerves (easily accessible for both focal electrophysiological recording and morphological studies) and the low number of resident immune cell types, distinguished from those cells migrating from blood vessels. This paper presents an overview of the corneal structure and innervation, the resident dendritic cell (DC) subpopulations present in the cornea, their distribution in relation to corneal nerves, and their role in ocular inflammatory diseases. A mouse model in which sensory axons are constitutively labeled with tdTomato and DCs with green fluorescent protein (GFP) allows further analysis of the neuro-immune crosstalk under inflammatory and steady-state conditions of the eye.

Disruption of c-MYC Binding and Chromosomal Looping Involving Genetic Variants Associated With Ankylosing Spondylitis Upstream of the RUNX3 Promoter

Background: Ankylosing Spondylitis (AS) is a common form of inflammatory spinal arthritis with a complex aetiology and high heritability, involving more than 100 genetic associations. These include several AS-associated single nucleotide polymorphisms (SNPs) upstream of RUNX3, which encodes the multifunctional RUNT-related transcription factor (TF) 3. The lead associated SNP rs6600247 (p = 2.6 × 10⁻¹⁵) lies ∼13kb upstream of the RUNX3 promoter adjacent to a c-MYC TF binding-site. The effect of rs6600247 genotype on DNA binding and chromosome looping were investigated by electrophoretic mobility gel shift assays (EMSA), Western blotting-EMSA (WEMSA) and Chromosome Conformation Capture (3C).

Results: Interrogation of ENCODE published data showed open chromatin in the region overlapping rs6600247 in primary human CD14⁺ monocytes, in contrast to the Jurkat T cell line or primary human T-cells. The rs6600247 AS-risk allele is predicted to specifically disrupt a c-MYC binding-site. Using a 50bp DNA probe spanning rs6600247 we consistently observed reduced binding to the AS-risk “C” allele of both purified c-MYC protein and nuclear extracts (NE) from monocyte-like U937 cells. WEMSA on U937 NE and purified c-MYC protein confirmed these differences (n = 3; p < 0.05). 3C experiments demonstrated negligible interaction between the region encompassing rs6600247 and the RUNX3 promoter. A stronger interaction frequency was demonstrated between the RUNX3 promoter and the previously characterised AS-associated SNP rs4648889.

Conclusion: The lead SNP rs6600247, located in an enhancer-like region upstream of the RUNX3 promoter, modulates c-MYC binding. However, the region encompassing rs6600247 has rather limited physical interaction with the promoter of RUNX3. In contrast a clear chromatin looping event between the region encompassing rs4648889 and the RUNX3 promoter was observed. These data provide further evidence for complexity in the regulatory elements upstream of the RUNX3 promoter and the involvement of RUNX3 transcriptional regulation in AS.

Thymic macrophages consist of two populations with distinct localization and origin

Tissue-resident macrophages are essential to protect from pathogen invasion and maintain organ homeostasis. The ability of thymic macrophages to engulf apoptotic thymocytes is well appreciated, but little is known about their ontogeny, maintenance, and diversity. Here, we characterized the surface phenotype and transcriptional profile of these cells and defined their expression signature. Thymic macrophages were most closely related to spleen red pulp macrophages and Kupffer cells and shared the expression of the transcription factor (TF) SpiC with these cells. Single-cell RNA sequencing (scRNA-Seq) showed that the macrophages in the adult thymus are composed of two populations distinguished by the expression of Timd4 and Cx3cr1. Remarkably, Timd4⁺ cells were located in the cortex, while Cx3cr1⁺ macrophages were restricted to the medulla and the cortico-medullary junction. Using shield chimeras, transplantation of embryonic thymuses, and genetic fate mapping, we found that the two populations have distinct origins. Timd4⁺ thymic macrophages are of embryonic origin, while Cx3cr1⁺ macrophages are derived from adult hematopoietic stem cells. Aging has a profound effect on the macrophages in the thymus. Timd4⁺ cells underwent gradual attrition, while Cx3cr1⁺ cells slowly accumulated with age and, in older mice, were the dominant macrophage population in the thymus. Altogether, our work defines the phenotype, origin, and diversity of thymic macrophages.

Runx Transcription Factors in T Cells-What Is Beyond Thymic Development?

Runx proteins (also known as Runt-domain transcription factors) have been studied for a long time as key regulators of cellular differentiation. RUNX2 has been described as essential for osteogenesis, whereas RUNX1 and RUNX3 are known to control blood cell development during different stages of cell lineage specification. However, recent studies show evidence of complex relationships between RUNX proteins, chromatin-modifying machinery, the cytoskeleton and different transcription factors in various non-embryonic contexts, including mature T cell homeostasis, inflammation and cancer. In this review, we discuss the diversity of Runx functions in mature T helper cells, such as production of cytokines and chemokines by different CD4 T cell populations; apoptosis; and immunologic memory acquisition. We then briefly cover recent findings about the contribution of RUNX1, RUNX2 and RUNX3 to various immunologic diseases. Finally, we discuss areas that require further study to better understand the role that Runx proteins play in inflammation and immunity.

RUNX3 Expression Level Is Correlated with the Clinical and Pathological Characteristics in Endometrial Cancer: A Systematic Review and Meta-analysis

Human Runt-associated transcription factor 3 (RUNX3) plays an important role in the development and progression of endometrial cancer (EC). However, the clinical and pathological significance of RUNX3 in EC needs to be further studied. In order to clarify the clinical and pathological significance of RUNX3, a systematic review and meta-analysis was conducted in EC patients. Keywords RUNX3, endometrial cancer, and uterine cancer were searched in Cochrane Library, Web of Knowledge, PubMed, CBM, MEDLINE, and Chinese CNKI database for data up to Dec 31, 2018. References, abstracts, and meeting proceedings were manually searched in supplementary. Outcomes were various clinical and pathological features. The two reviewers performed the literature searching, data extracting, and method assessing independently. Meta-analysis was performed by RevMan5.3.0. A total of 563 EC patients were enrolled from eight studies. Meta-analysis results showed that the expression of RUNX3 has significant differences in these comparisons: lymph node (LN) metastasis vs. non-LN metastasis (P = 0.26), EC tissues vs. normal tissues (P < 0.00001), clinical stages I/II vs. II/IV (P < 0.00001), muscular infiltration < 1/2 vs. muscular infiltration ≥ 1/2 (P < 0.00001), and G1 vs. G2/G3 (P < 0.00001). The decreasing expression of RUNX3 is associated with poor TNM stage and muscular infiltration. It is indicated that RUNX3 was involved in the suppression effect of EC. However, further multicenter randomized controlled trials are needed considering the small sample size of the included trials.

Apoptotic cell signals and heterogeneity in macrophage function: Fine-tuning for a healthy liver

Functional heterogeneity in tissue macrophage populations has often been traced to developmental and spatial cues. Upon tissue damage, macrophages are exposed to soluble mediators secreted by activated cells, which shape their polarisation. Interestingly, macrophages are concomitantly exposed to a variety of different dying cells, which carry miscellaneous signals and that need to be recognised and promptly up-taken by professional phagocytes. This review discusses how differences in the nature of the dying cells, like their morphological and biochemical features as well as the specificity of phagocytic receptor usage on macrophages, might contribute to the transcriptional and functional heterogeneity observed in phagocytic cells in the tissue.

The miR-424(322)/503 gene cluster regulates pro- versus anti-inflammatory skin DC subset differentiation by modulating TGF-β signaling

Transforming growth factor β (TGF-β) family ligands are key regulators of dendritic cell (DC) differentiation and activation. Epidermal Langerhans cells (LCs) require TGF-β family signaling for their differentiation, and canonical TGF-β1 signaling secures a non-activated LC state. LCs reportedly control skin inflammation and are replenished from peripheral blood monocytes, which also give rise to pro-inflammatory monocyte-derived DCs (moDCs). By studying mechanisms in inflammation, we previously screened LCs versus moDCs for differentially expressed microRNAs (miRNAs). This revealed that miR-424/503 is the most strongly inversely regulated (moDCs > LCs). We here demonstrate that miR-424/503 is induced during moDC differentiation and promotes moDC differentiation in human and mouse. Inversely, forced repression of miR-424 during moDC differentiation facilitates TGF-β1-dependent LC differentiation. Mechanistically, miR-424/503 deficiency in monocyte/DC precursors leads to the induction of TGF-β1 response genes critical for LC differentiation. Therefore, the miR-424/503 gene cluster plays a decisive role in anti-inflammatory LC versus pro-inflammatory moDC differentiation from monocytes.

Targeting macrophages in cancer immunotherapy

Immunotherapy is regarded as the most promising treatment for cancers. Various cancer immunotherapies, including adoptive cellular immunotherapy, tumor vaccines, antibodies, immune checkpoint inhibitors, and small-molecule inhibitors, have achieved certain successes. In this review, we summarize the role of macrophages in current immunotherapies and the advantages of targeting macrophages. To better understand and make better use of this type of cell, their development and differentiation characteristics, categories, typical markers, and functions were collated at the beginning of the review. Therapeutic strategies based on or combined with macrophages have the potential to improve the treatment efficacy of cancer therapies.

Fine particulate matter induces airway inflammation by disturbing the balance between Th1/Th2 and regulation of GATA3 and Runx3 expression in BALB/c mice

The present study aimed to examine the effects of 2.5 µm particulate matter (PM2.5) on airway inflammation and to investigate the possible underlying mechanism. Specifically, the focus was on the imbalance of T helper (Th)1/Th2 cells and the dysregulated expression of transcription factors, including trans-acting T cell-specific transcription factor 3 (GATA3), runt-related transcription factor 3 (Runx3) and T-box transcription factor TBX21 (T-bet). In this study, ambient PM2.5 was collected and analyzed, male BALB/c mice were sensitized and treated with PBS, ovalbumin (OVA), PM2.5 or OVA + PM2.5. The effects of PM2.5 alone or PM2.5 + OVA on immunopathological changes, the expression of transcription factors GATA3, Runx3 and T-bet, and the imbalance of Th1/Th2 were investigated. It was found that PM2.5 + OVA co-exposure significantly enhanced inflammatory cell infiltration, increased higher tracheal secretions in lung tissue and upregulated respiratory resistance response to acetylcholine compared with PM2.5 or OVA single exposure and control groups. In addition, higher protein and mRNA expression levels of Th2 inflammatory mediators interleukin (IL)-4, IL-5 and IL-13 in bronchoalveolar lavage fluid were observed in PM2.5 + OVA treated mice, whereas the expression levels of GATA3 and STAT6 were exhibited in mice exposed to OVA + PM2.5 compared with the OVA and PM2.5 groups. By contrast, PM2.5 exposure decreased the protein and mRNA expression levels of Th1 cytokine interferon-γ and transcription factors Runx3 and T-bet, especially among asthmatic mice, different from OVA group, PM2.5 exposure only failed to influence the expression of T-bet. To conclude, PM2.5 exposure evoked the allergic airway inflammation response, especially in the asthmatic mouse model and led to Th1/Th2 imbalance. These effects worked mainly by upregulating GATA3 and downregulating Runx3. These data suggested that Runx3 may play an important role in PM2.5-aggravated asthma in BALB/c mice.

Waiting in the wings: RUNX3 reveals hidden depths of immune regulation with potential implications for inflammatory bowel disease

BACKGROUND

Complex interactions between the environment and the mucosal immune system underlie inflammatory bowel disease (IBD). The involved cytokine signalling pathways are modulated by a number of transcription factors, one of which is runt-related transcription factor 3 (RUNX3).

OBJECTIVE

To systematically review the immune roles of RUNX3 in immune regulation, with a focus on the context of IBD.

METHODS

Relevant articles and reviews were identified through a Scopus search in April 2020. Information was categorized by immune cell types, analysed and synthesized. IBD transcriptome data sets and FANTOM5 regulatory networks were processed in order to complement the literature review.

RESULTS

The available evidence on the immune roles of RUNX3 allowed for its description in twelve cell types: intraepithelial lymphocyte, Th1, Th2, Th17, Treg, double-positive T, cytotoxic T, B, dendritic, innate lymphoid, natural killer and macrophages. In the gut, the activity of RUNX3 is multifaceted and context-dependent: it may promote homeostasis or exacerbated reactions via cytokine signalling and regulation of receptor expression. RUNX3 is mostly engaged in pathways involving ThPOK, T-bet, IFN-γ, TGF-β/IL-2Rβ, GATA/CBF-β, SMAD/p300 and a number of miRNAs. RUNX3 targets relevant to IBD may include RAG1, OSM and IL-17B. Moreover, in IBD RUNX3 expression correlates positively with GZMM, and negatively with IFNAR1, whereas in controls, it strongly associates with TGFBR3.

CONCLUSIONS

Dysregulation of RUNX3, mostly in the form of deficiency, likely contributes to IBD pathogenesis. More clinical research is needed to examine RUNX3 in IBD.

Tumor-infiltrating dendritic cell states are conserved across solid human cancers

Dendritic cells (DCs) contribute a small fraction of the tumor microenvironment but are emerging as an essential antitumor component based on their ability to foster T cell immunity and immunotherapy responses. Here, we discuss our expanding view of DC heterogeneity in human tumors, as revealed with meta-analysis of single-cell transcriptome profiling studies. We further examine tumor-infiltrating DC states that are conserved across patients, cancer types, and species and consider the fundamental and clinical relevance of these findings. Finally, we provide an outlook on research opportunities to further explore mechanisms governing tumor-infiltrating DC behavior and functions.

Runx proteins mediate protective immunity against Leishmania donovani infection by promoting CD40 expression on dendritic cells

The level of CD40 expression on dendritic cells (DCs) plays a decisive role in disease protection during Leishmania donovani (LD) infection. However, current understanding of the molecular regulation of CD40 expression remains elusive. Using molecular, cellular and functional approaches, we identified a role for Runx1 and Runx3 transcription factors in the regulation of CD40 expression in DCs. In response to lipopolysaccharide (LPS), tumor necrosis factor alpha (TNFα) or antileishmanial drug sodium antimony gluconate (SAG), both Runx1 and Runx3 translocated to the nucleus, bound to the CD40 promoter and upregulated CD40 expression on DCs. These activities of Runx proteins were mediated by the upstream phosphatidylinositol 3-kinase (PI3K)-Akt pathway. Notably, LD infection attenuated LPS- or TNFα-induced CD40 expression in DCs by inhibiting PI3K-Akt-Runx axis via protein tyrosine phosphatase SHP-1. In contrast, CD40 expression induced by SAG was unaffected by LD infection, as SAG by blocking LD-induced SHP-1 activation potentiated PI3K-Akt signaling to drive Runx-mediated CD40 upregulation. Adoptive transfer experiments further showed that Runx1 and Runx3 play a pivotal role in eliciting antileishmanial immune response of SAG-treated DCs in vivo by promoting CD40-mediated type-1 T cell responses. Importantly, antimony-resistant LD suppressed SAG-induced CD40 upregulation on DCs by blocking the PI3K-Akt-Runx pathway through sustained SHP-1 activation. These findings unveil an immunoregulatory role for Runx proteins during LD infection.

Single-cell analyses and machine learning define hematopoietic progenitor and HSC-like cells derived from human PSCs

Hematopoietic stem and progenitor cells (HSPCs) develop in distinct waves at various anatomical sites during embryonic development. The in vitro differentiation of human pluripotent stem cells (hPSCs) recapitulates some of these processes; however, it has proven difficult to generate functional hematopoietic stem cells (HSCs). To define the dynamics and heterogeneity of HSPCs that can be generated in vitro from hPSCs, we explored single-cell RNA sequencing (scRNAseq) in combination with single-cell protein expression analysis. Bioinformatics analyses and functional validation defined the transcriptomes of naïve progenitors and erythroid-, megakaryocyte-, and leukocyte-committed progenitors, and we identified CD44, CD326, ICAM2/CD9, and CD18, respectively, as markers of these progenitors. Using an artificial neural network that we trained on scRNAseq derived from human fetal liver, we identified a wide range of hPSC-derived HSPCs phenotypes, including a small group classified as HSCs. This transient HSC-like population decreased as differentiation proceeded, and was completely missing in the data set that had been generated using cells selected on the basis of CD43 expression. By comparing the single-cell transcriptome of in vitro-generated HSC-like cells with those generated within the fetal liver, we identified transcription factors and molecular pathways that can be explored in the future to improve the in vitro production of HSCs.

Macrophage Modification Strategies for Efficient Cell Therapy

Macrophages, important cells of innate immunity, are known for their phagocytic activity, capability for antigen presentation, and flexible phenotypes. Macrophages are found in all tissues and therefore represent an attractive therapeutic target for the treatment of diseases of various etiology. Genetic programming of macrophages is an important issue of modern molecular and cellular medicine. The controllable activation of macrophages towards desirable phenotypes in vivo and in vitro will provide effective treatments for a number of inflammatory and proliferative diseases. This review is focused on the methods for specific alteration of gene expression in macrophages, including the controllable promotion of the desired M1 (pro-inflammatory) or M2 (anti-inflammatory) phenotypes in certain pathologies or model systems. Here we review the strategies of target selection, the methods of vector delivery, and the gene editing approaches used for modification of macrophages.

Runx3 prevents spontaneous colitis by directing the differentiation of anti-inflammatory mononuclear phagocytes

Mice deficient in the transcription factor Runx3 develop a multitude of immune system defects, including early onset colitis. This paper demonstrates that Runx3 is expressed in colonic mononuclear phagocytes (MNP), including resident macrophages (RM) and dendritic cell subsets (cDC2). Runx3 deletion in MNP causes early onset colitis due to their impaired maturation. Mechanistically, the resulting MNP subset imbalance leads to up-regulation of pro-inflammatory genes as occurs in IL10R-deficient RM. In addition, RM and cDC2 display a marked decrease in expression of anti-inflammatory/TGF β-regulated genes and β-catenin signaling associated genes, respectively. MNP transcriptome and ChIP-seq data analysis suggest that a significant fraction of genes affected by Runx3 loss are direct Runx3 targets. Collectively, Runx3 imposes intestinal immune tolerance by regulating maturation of colonic anti-inflammatory MNP, befitting the identification of RUNX3 as a genome-wide associated risk gene for various immune-related diseases in humans, including gastrointestinal tract diseases such as Crohn’s disease and celiac.

RUNX3 Polymorphisms Affect the Risk of Ankylosing Spondylitis

Background

We aimed to assess the potential association of runt-related transcription factor 3 (RUNX3) gene variants with ankylosing spondylitis (AS) susceptibility among Chinese Han people.

Material/Methods

Genotyping for RUNX3 variants was accomplished through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 115 AS patients and 102 healthy controls. Genotypes distributions of the polymorphisms in controls was assessed for their deviation from Hardy-Weinberg equilibrium (HWE). Moreover, odds ratio (OR) with 95% confidence interval (95%CI) was achieved using chi-square analysis to evaluate AS risk related to RUNX3 polymorphisms. Additionally, logistic regression analysis produced adjusted OR values.

Results

Genotypes distribution of rs760805 and rs11249206 polymorphisms conformed to HWE in the control group (P>0.05). TT genotype of rs760805 appeared more frequently among AS cases than in controls (P=0.033), indicating its significant association with increased risk of AS onset (OR=2.309, 95%CI=1.069–4.892). The carriage of T allele in rs760805 also heightened AS incidence, in comparison to A allele (OR=1.578, 95%CI=1.075–2.316, P=0.020). Moreover, the carriage of AT+TT genotype in rs760805 and TT genotype in rs11249206 obviously increased risk of AS onset (OR=2.585, 95%CI=1.062–6.288).

Conclusions

RUNX3 rs760805 polymorphism can contribute to AS incidence in Chinese Han people. The interaction of the 2 polymorphisms may be a risk factor for AS.

RUNX3 levels in human hematopoietic progenitors are regulated by aging and dictate erythroid-myeloid balance

Healthy bone marrow progenitors yield a co-ordinated balance of hematopoietic lineages. This balance shifts with aging toward enhanced granulopoiesis with diminished erythropoiesis and lymphopoiesis, changes which likely contribute to the development of bone marrow disorders in the elderly. In this study, RUNX3 was identified as a hematopoietic stem and progenitor cell factor whose levels decline with aging in humans and mice. This decline is exaggerated in hematopoietic stem and progenitor cells from subjects diagnosed with unexplained anemia of the elderly. Hematopoietic stem cells from elderly unexplained anemia patients had diminished erythroid but unaffected granulocytic colony forming potential. Knockdown studies revealed human hematopoietic stem and progenitor cells to be strongly influenced by RUNX3 levels, with modest deficiencies abrogating erythroid differentiation at multiple steps while retaining capacity for granulopoiesis. Transcriptome profiling indicated control by RUNX3 of key erythroid transcription factors, including KLF1 and GATA1 These findings thus implicate RUNX3 as a participant in hematopoietic stem and progenitor cell aging, and a key determinant of erythroid-myeloid lineage balance.

Runx-mediated regulation of CCL5 via antagonizing two enhancers influences immune cell function and anti-tumor immunity

CCL5 is a unique chemokine with distinct stage and cell-type specificities for regulating inflammation, but how these specificities are achieved and how CCL5 modulates immune responses is not well understood. Here we identify two stage-specific enhancers: the proximal enhancer mediates the constitutive CCL5 expression during the steady state, while the distal enhancer located 1.35 Mb from the promoter induces CCL5 expression in activated cells. Both enhancers are antagonized by RUNX/CBFβ complexes, and SATB1 further mediates the long-distance interaction of the distal enhancer with the promoter. Deletion of the proximal enhancer decreases CCL5 expression and augments the cytotoxic activity of tissue-resident T and NK cells, which coincides with reduced melanoma metastasis in mouse models. By contrast, increased CCL5 expression resulting from RUNX3 mutation is associated with more tumor metastasis in the lung. Collectively, our results suggest that RUNX3-mediated CCL5 repression is critical for modulating anti-tumor immunity.

CCL5 is an important chemokine for modulation of inflammatory responses, but how CCL5 expression is regulated is still unclear. Here the authors show that the CCL5 locus contains two enhancers, with the proximal enhancer being responsible for homeostatic expression and the distal enhancer enforcing inducibility, while both enhancers are modulated by RUNX3.

Essential functions of Runx/Cbfβ in gut conventional dendritic cells for priming Rorγt+ T cells

Loss of Runx/Cbfβ complexes during DC development leads to a loss of gut CD103⁺CD11b⁺ cDC2s, which was accompanied with impaired differentiation of both Rorγt⁺ Th17 cells and type 3 Rorγt⁺ Treg cells.

Acquired immune responses are initiated by activation of CD4⁺ helper T (Th) cells via recognition of antigens presented by conventional dendritic cells (cDCs). DCs instruct Th-cell polarization program into specific effector Th subset, which will dictate the type of immune responses. Hence, it is important to unravel how differentiation and/or activation of DC are linked with Th-cell–intrinsic mechanism that directs differentiation toward a specific effector Th subset. Here, we show that loss of Runx/Cbfβ transcription factors complexes during DC development leads to loss of CD103⁺CD11b⁺ cDC2s and alters characteristics of CD103⁻CD11b⁺ cDCs in the intestine, which was accompanied with impaired differentiation of Rorγt⁺ Th17 cells and type 3 Rorγt⁺ regulatory T cells. We also show that a Runx-binding enhancer in the Rorc gene is essential for T cells to integrate cDC-derived signals to induce Rorγt expression. These findings reveal that Runx/Cbfβ complexes play crucial and complementary roles in cDCs and Th cells to shape converging type 3 immune responses.

[Expression and clinical significance of runt-related transcription factor 3 in children with bronchiolitis]

OBJECTIVE

To study the mRNA level of runt-related transcription factor 3 (RUNX3) in children with bronchiolitis and its clinical significance in bronchiolitis.

METHODS

A total of 54 young children with bronchiolitis were enrolled as the bronchiolitis group, among whom 28 with atopic constitution were enrolled in the atopic bronchiolitis group and 26 with non-atopic constitution were enrolled in the non-atopic bronchiolitis group. A total of 48 healthy young children were enrolled as the healthy control group, among whom 24 with atopic constitution were enrolled in the atopic healthy control group and 24 with non-atopic constitution were enrolled in the non-atopic healthy control group. Quantitative real-time PCR was used to measure the mRNA level of RUNX3 in peripheral blood mononuclear cells. ELISA was used to measure the serum levels of interleukin-4 (IL-4) and interferon gamma (IFN-γ).

RESULTS

The bronchiolitis group had a significantly lower mRNA level of RUNX3 than the healthy control group, and the atopic bronchiolitis group had a significantly lower mRNA level of RUNX3 than the non-atopic bronchiolitis, atopic healthy control, and non-atopic healthy control groups (P<0.05). The bronchiolitis group had a significantly higher serum level of IL-4 than the healthy control group, and the atopic bronchiolitis group had a significantly higher serum level of IL-4 than the non-atopic healthy control group (P<0.05). The bronchiolitis group had a significantly lower serum level of IFN-γ than the healthy control group, and the atopic bronchiolitis group had a significantly lower serum level of IFN-γ than the non-atopic bronchiolitis, atopic healthy control, and non-atopic healthy control groups (P<0.05). The correlation analysis showed that the mRNA level of RUNX3 was negatively correlated with the serum level of IL-4 and was positively correlated with the serum level of IFN-γ (P<0.05).

CONCLUSIONS

Measurement of RUNX3 gene expression in peripheral blood mononuclear cells has a certain value in identifying children with atopic constitution at high risk of asthma among children with bronchiolitis.

Methylation Landscape of RUNX3 Promoter Region as a Predictive Marker for Th1/Th2 Imbalance in Bronchiolitis

Background

The methylation status of RUNX3 promoter region, its impact on RUNX3 gene expression, and Th1/Th2 imbalance are unknown in bronchiolitis. This study aimed to explore the predictors of bronchiolitis developing into asthma.

Material/Methods

The methylation status of RUNX3 promoter was assessed using Illumina HiSeq platform method. The relative RUNX3 mRNA levels in PBMCs were measured by qRT-PCR. Serum IL-4 and IFN-γ concentrations were measured by ELISA.

Results

A series of sites with significantly higher levels of methylation as compared to their corresponding controls were identified, including 24 sites in group Ba vs. group Cn, 13 sites in group Ba vs. group Ca, 7 sites in group Ba vs. group Bn, 16 sites in group Bn vs. group Cn, 11 sites in group Ca vs. group Cn, and 23 sites in group B vs. group C; P<0.05. The relative mRNA levels in group Ba were significantly lower than those in groups Cn, Ca, Bn; P<0.05. The serum IL-4 concentrations in group Ba were significantly higher than those in group Cn; P<0.05. The serum IFN-γ concentrations in group Ba were significantly lower than those in groups Cn, Ca, Bn; P<0.05. Correlation analysis showed that differentially methylated RUNX3 promoter region sites were significantly negatively correlated with levels of relative RUNX3 mRNA and IFN-γ, and were significantly positively correlated with IL-4 levels.

Conclusions

The methylation status of RUNX3 promoter region plays a role in Th1/Th2 imbalance by silencing RUNX3 gene expression, which can serve as predictive marker for the development of bronchiolitis into asthma.

[Expression and clinical significance of runt-related transcription factor 3 in children with bronchiolitis]

OBJECTIVE

To study the mRNA level of runt-related transcription factor 3 (RUNX3) in children with bronchiolitis and its clinical significance in bronchiolitis.

METHODS

A total of 54 young children with bronchiolitis were enrolled as the bronchiolitis group, among whom 28 with atopic constitution were enrolled in the atopic bronchiolitis group and 26 with non-atopic constitution were enrolled in the non-atopic bronchiolitis group. A total of 48 healthy young children were enrolled as the healthy control group, among whom 24 with atopic constitution were enrolled in the atopic healthy control group and 24 with non-atopic constitution were enrolled in the non-atopic healthy control group. Quantitative real-time PCR was used to measure the mRNA level of RUNX3 in peripheral blood mononuclear cells. ELISA was used to measure the serum levels of interleukin-4 (IL-4) and interferon gamma (IFN-γ).

RESULTS

The bronchiolitis group had a significantly lower mRNA level of RUNX3 than the healthy control group, and the atopic bronchiolitis group had a significantly lower mRNA level of RUNX3 than the non-atopic bronchiolitis, atopic healthy control, and non-atopic healthy control groups (P<0.05). The bronchiolitis group had a significantly higher serum level of IL-4 than the healthy control group, and the atopic bronchiolitis group had a significantly higher serum level of IL-4 than the non-atopic healthy control group (P<0.05). The bronchiolitis group had a significantly lower serum level of IFN-γ than the healthy control group, and the atopic bronchiolitis group had a significantly lower serum level of IFN-γ than the non-atopic bronchiolitis, atopic healthy control, and non-atopic healthy control groups (P<0.05). The correlation analysis showed that the mRNA level of RUNX3 was negatively correlated with the serum level of IL-4 and was positively correlated with the serum level of IFN-γ (P<0.05).

CONCLUSIONS

Measurement of RUNX3 gene expression in peripheral blood mononuclear cells has a certain value in identifying children with atopic constitution at high risk of asthma among children with bronchiolitis.

RUNX transcription factors: orchestrators of development

RUNX transcription factors orchestrate many different aspects of biology, including basic cellular and developmental processes, stem cell biology and tumorigenesis. In this Primer, we introduce the molecular hallmarks of the three mammalian RUNX genes, RUNX1, RUNX2 and RUNX3, and discuss the regulation of their activities and their mechanisms of action. We then review their crucial roles in the specification and maintenance of a wide array of tissues during embryonic development and adult homeostasis.

Delineating the origins, developmental programs and homeostatic functions of tissue-resident macrophages

A literature covering 150 years of research indicates that macrophages are a diverse family of professional phagocytes that continuously explore their environment, recognize and scavenge pathogens, unfit cells, cell debris as well as metabolites, and produce a large range of bioactive molecules and growth factors. A new paradigm suggests that most tissue-resident macrophages originate from fetal precursors that colonize developing organs and self-maintain independently of bone marrow-derived cells throughout life. The differentiation of these precursors is driven by a core macrophage transcriptional program and immediately followed by their specification through expression of tissue-specific transcriptional regulators early during embryogenesis. Despite our increasing understanding of ontogeny and genetic programs that shape differentiation processes and functions of macrophages, the precise developmental trajectories of tissue-resident macrophages remain undefined. Here, I review current models of fetal hematopoietic waves, possible routes of macrophage development and their roles during homeostasis. Further, transgenic mouse models are discussed providing a toolset to study the developmentally and functionally distinct arms of the phagocyte system in vivo.

Selective deployment of transcription factor paralogs with submaximal strength facilitates gene regulation in the immune system

In multicellular organisms, duplicated genes can diverge through tissue-specific gene expression patterns, as exemplified by highly regulated expression of Runx transcription factor paralogs with apparent functional redundancy. Here we asked what cell type-specific biologies might be supported by the selective expression of Runx paralogs during Langerhans cell and inducible regulatory T cell differentiation. We uncovered functional non-equivalence between Runx paralogs. Selective expression of native paralogs allowed integration of transcription factor activity with extrinsic signals, while non-native paralogs enforced differentiation even in the absence of exogenous inducers. DNA-binding affinity was controlled by divergent amino acids within the otherwise highly conserved RUNT domain, and evolutionary reconstruction suggested convergence of RUNT domain residues towards sub-maximal strength. Hence, the selective expression of gene duplicates in specialized cell types can synergize with the acquisition of functional differences to enable appropriate gene expression, lineage choice and differentiation in the mammalian immune system.

Studying tissue macrophages in vitro: are iPSC-derived cells the answer?

Macrophages are immune cells with important roles in tissue homeostasis, inflammation and pathologies. Hence, macrophage populations represent promising targets for modern medicine. Exploiting the potential of macrophage-targeted therapies will require a thorough understanding of the mechanisms controlling their development, specialization and maintenance throughout their lifespan. Macrophages have been studied in vitro for many years, but recent advances in the field of macrophage biology have called into question the validity of traditional approaches. New models, such as recent innovations in generating macrophages from induced pluripotent stem cells (iPSCs), must take into account the impact of heterogeneity in the origin and tissue-specific functions of macrophages. Here, we discuss these protocols and argue for a better understanding of the type of macrophages made in vitro; we also encourage recognition of the importance of tissue identity of macrophages, which cannot be recapitulated by cytokine-dependent protocols. We suggest that a two-step model - in which iPSC-derived macrophages are first generated based on their ontogeny and then conditioned by their tissue-specific environment - offers immense potential for generating biologically relevant macrophages for future studies.

Low RUNX3 expression alters dendritic cell function in patients with systemic sclerosis and contributes to enhanced fibrosis

Objectives

Systemic sclerosis (SSc) is an autoimmune disease with unknown pathogenesis manifested by inflammation, vasculopathy and fibrosis in skin and internal organs. Type I interferon signature found in SSc propelled us to study plasmacytoid dendritic cells (pDCs) in this disease. We aimed to identify candidate pathways underlying pDC aberrancies in SSc and to validate its function on pDC biology.

Methods

In total, 1193 patients with SSc were compared with 1387 healthy donors and 8 patients with localised scleroderma. PCR-based transcription factor profiling and methylation status analyses, single nucleotide polymorphism genotyping by sequencing and flow cytometry analysis were performed in pDCs isolated from the circulation of healthy controls or patients with SSc. pDCs were also cultured under hypoxia, inhibitors of methylation and hypoxia-inducible factors and runt-related transcription factor 3 (RUNX3) levels were determined. To study Runx3 function, Itgax-Cre:Runx3f/f mice were used in in vitro functional assay and bleomycin-induced SSc skin inflammation and fibrosis model.

Results

Here, we show downregulation of transcription factor RUNX3 in SSc pDCs. A higher methylation status of the RUNX3 gene, which is associated with polymorphism rs6672420, correlates with lower RUNX3 expression and SSc susceptibility. Hypoxia is another factor that decreases RUNX3 level in pDC. Mouse pDCs deficient of Runx3 show enhanced maturation markers on CpG stimulation. In vivo, deletion of Runx3 in dendritic cell leads to spontaneous induction of skin fibrosis in untreated mice and increased severity of bleomycin-induced skin fibrosis.

Conclusions

We show at least two pathways potentially causing low RUNX3 level in SSc pDCs, and we demonstrate the detrimental effect of loss of Runx3 in SSc model further underscoring the role of pDCs in this disease.

The Dynamics of the Skin's Immune System

The skin is a complex organ that has devised numerous strategies, such as physical, chemical, and microbiological barriers, to protect the host from external insults. In addition, the skin contains an intricate network of immune cells resident to the tissue, crucial for host defense as well as tissue homeostasis. In the event of an insult, the skin-resident immune cells are crucial not only for prevention of infection but also for tissue reconstruction. Deregulation of immune responses often leads to impaired healing and poor tissue restoration and function. In this review, we will discuss the defensive components of the skin and focus on the function of skin-resident immune cells in homeostasis and their role in wound healing.

RUNX3 and T-Bet in Immunopathogenesis of Ankylosing Spondylitis-Novel Targets for Therapy?

Susceptibility to ankylosing spondylitis (AS) is polygenic with more than 100 genes identified to date. These include HLA-B27 and the aminopeptidases (ERAP1, ERAP2, and LNPEPS), which are involved in antigen processing and presentation to T-cells, and several genes (IL23R, IL6R, STAT3, JAK2, IL1R1/2, IL12B, and IL7R) involved in IL23 driven pathways of inflammation. AS is also strongly associated with polymorphisms in two transcription factors, RUNX3 and T-bet (encoded by TBX21), which are important in T-cell development and function. The influence of these genes on the pathogenesis of AS and their potential for identifying drug targets is discussed here.

Epidermal γδ T cells originate from yolk sac hematopoiesis and clonally self-renew in the adult

The adult turnover mechanisms and hematopoietic origin of dendritic epidermal γδ T cells (DETCs) are poorly characterized. Gentek et al. demonstrate that DETCs originate from yolk sac hematopoiesis and clonally self-renew in the adult, akin to epidermal Langerhans cells.

The murine epidermis harbors two immune cell lineages, Langerhans cells (LCs) and γδ T cells known as dendritic epidermal T cells (DETCs). LCs develop from both early yolk sac (YS) progenitors and fetal liver monocytes before locally self-renewing in the adult. For DETCs, the mechanisms of homeostatic maintenance and their hematopoietic origin are largely unknown. Here, we exploited multicolor fate mapping systems to reveal that DETCs slowly turn over at steady state. Like for LCs, homeostatic maintenance of DETCs is achieved by clonal expansion of tissue-resident cells assembled in proliferative units. The same mechanism, albeit accelerated, facilitates DETC replenishment upon injury. Hematopoietic lineage tracing uncovered that DETCs are established independently of definitive hematopoietic stem cells and instead originate from YS hematopoiesis, again reminiscent of LCs. DETCs thus resemble LCs concerning their maintenance, replenishment mechanisms, and hematopoietic development, suggesting that the epidermal microenvironment exerts a lineage-independent influence on the initial seeding and homeostatic maintenance of its resident immune cells.

RARα supports the development of Langerhans cells and langerin-expressing conventional dendritic cells

Langerhans cells (LC) are the prototype langerin-expressing dendritic cells (DC) that reside specifically in the epidermis, but langerin-expressing conventional DCs also reside in the dermis and other tissues, yet the factors that regulate their development are unclear. Because retinoic acid receptor alpha (RARα) is highly expressed by LCs, we investigate the functions of RARα and retinoic acid (RA) in regulating the langerin-expressing DCs. Here we show that the development of LCs from embryonic and bone marrow-derived progenitors and langerin⁺ conventional DCs is profoundly regulated by the RARα-RA axis. During LC differentiation, RARα is required for the expression of a LC-promoting transcription factor Runx3, but suppresses that of LC-inhibiting C/EBPβ. RARα promotes the development of LCs and langerin⁺ conventional DCs only in hypo-RA conditions, a function effectively suppressed at systemic RA levels. Our findings identify positive and negative regulatory mechanisms to tightly regulate the development of the specialized DC populations.

Langerhans cells (LC) and langerin-expressing conventional dendritic cells are made from distinct progenitors and enriched in the distinct microenvironments of the skin. Here the authors show that these immune cells are regulated by retinoic acid receptor alpha (RARα) via simultaneous induction of LC-promoting Runx3 and repression of LC-inhibiting C/EBPβ.

The correlation between Runx3 and bronchial asthma

Runx3, a member of the Runt-related transcription factor family, has attracted extensive attention due to its important role in the development of immune systems, especially in the differentiation of T cells. Accumulated evidence indicated that altered expression of Runx3 regulates a variety of target genes in different tissues/cells. Studies in animal models suggested that Runx3 may regulate the development of T cell lineage including those of innate lymphoid cells, Treg cells and dendritic cells, which may contribute to the development of hypersensitivity and asthma. Specifically, Runx3 modulates Th1/Th2 balance and hence, the production of interleukins, which induce inflammatory responses. Understanding the roles and mechanisms of Runx3 in the regulation of immune function provides a basis for the design of novel preventive and treatment models for bronchial asthma. This article reviews published data from cell lines, animal models, and patients, concerning the relationship between Runx3 expression alteration and asthma. Epigenetic regulation of Runx3 by DNA hypermethylation and microRNA, and the implication of these pathways in asthma are also discussed.

Emerging role of RUNX3 in the regulation of tumor microenvironment

A number of genes have been therapeutically targeted to relieve cancer, but cancer relapse is still a growing issue. The concept that the surrounding tumor environment is critical for the progression of cancer may foster an answer to the issue of cancer malignancy. Runt domain transcription factors (RUNX1, 2, and 3) are evolutionarily conserved and have been intensively studied for their roles in normal development and pathological conditions. During tumor growth, a hypoxic microenvironment and infiltration of the tumor by immune cells are common phenomena. In this review, we briefly introduce the consequences of hypoxia and immune cell infiltration into the tumor microenvironment with a focus on RUNX3 as a critical regulator. Furthermore, based on our current knowledge of the functional role of RUNX3 in hypoxia and immune cell maintenance, a probable therapeutic intervention is suggested for the effective management of tumor growth and malignancy. [BMB Reports 2018; 51(4): 174-181].