Cooperative interaction of interferon regulatory factor -1 and bromodomain-containing protein 4 on RNA polymerase activation for intrinsic innate immunity

Introduction

The human orthopneumovirus, Respiratory Syncytial Virus (RSV), is the causative agent of severe lower respiratory tract infections (LRTI) and exacerbations of chronic lung diseases. In immune competent hosts, RSV productively infects highly differentiated epithelial cells, where it elicits robust anti-viral, cytokine and remodeling programs. By contrast, basal cells are relatively resistant to RSV infection, in part, because of constitutive expression of an intrinsic innate immune response (IIR) consisting of a subgroup of interferon (IFN) responsive genes. The mechanisms controlling the intrinsic IIR are not known.

Methods

Here, we use human small airway epithelial cell hSAECs as a multipotent airway stem cell model to examine regulatory control of an intrinsic IIR pathway.

Results

We find hSAECs express patterns of intrinsic IIRs, highly conserved with pluri- and multi-potent stem cells. We demonstrate a core intrinsic IIR network consisting of Bone Marrow Stromal Cell Antigen 2 (Bst2), Interferon Induced Transmembrane Protein 1 (IFITM1) and Toll-like receptor (TLR3) expression are directly under IRF1 control. Moreover, expression of this intrinsic core is rate-limited by ambient IRF1• phospho-Ser 2 CTD RNA Polymerase II (pSer2 Pol II) complexes binding to their proximal promoters. In response to RSV infection, the abundance of IRF1 and pSer2 Pol II binding is dramatically increased, with IRF1 complexing to the BRD4 chromatin remodeling complex (CRC). Using chromatin immunoprecipitation in IRF1 KD cells, we find that the binding of BRD4 is IRF1 independent. Using a small molecule inhibitor of the BRD4 acetyl lysine binding bromodomain (BRD4i), we further find that BRD4 bromodomain interactions are required for stable BRD4 promoter binding to the intrinsic IIR core promoters, as well as for RSV-inducible pSer2 Pol II recruitment. Surprisingly, BRD4i does not disrupt IRF1-BRD4 interactions, but disrupts both RSV-induced BRD4 and IRF1 interactions with pSer2 Pol II.

Conclusions

We conclude that the IRF1 functions in two modes- in absence of infection, ambient IRF1 mediates constitutive expression of the intrinsic IIR, whereas in response to RSV infection, the BRD4 CRC independently activates pSer2 Pol II to mediates robust expression of the intrinsic IIR. These data provide insight into molecular control of anti-viral defenses of airway basal cells.

Mesenchymal stem cell therapy for non-healing diabetic foot ulcer infection: New insight

Diabetic foot ulcer (DFU) is considered the most catastrophic complication of diabetes mellitus (DM), leading to repeated hospitalizations, infection, gangrene, and finally amputation of the limb. In patients suffering from diabetes mellitus, the wound-healing process is impaired due to various factors such as endothelial dysfunction and synthesis of advanced glycation end-products, hence, conventional therapeutic interventions might not be effective. With increasing therapeutic applications of mesenchymal stem cells (MSCs) in recent years, their potential as a method for improving the wound-healing process has gained remarkable attention. In this field, mesenchymal stem cells exert their beneficial effects through immunomodulation, differentiation into the essential cells at the site of ulcers, and promoting angiogenesis, among others. In this article, we review cellular and molecular pathways through which mesenchymal stem cell therapy reinforces the healing process in non-healing Diabetic foot ulcers.

Two novel CreERT2 transgenic mouse lines to study melanocytic cells in vivo

The skin of adult mammals protects from radiation, physical and chemical insults. While melanocytes and melanocyte-producing stem cells contribute to proper skin function in healthy organisms, dysfunction of these cells can lead to the generation of malignant melanoma - the deadliest type of skin cancer. Addressing cells of the melanocyte lineage in vivo represents a prerequisite for the understanding of melanoma on cellular level and the development of preventive and treatment strategies. Here, the inducible Cre-loxP-system has emerged as a promising tool to specifically target, monitor and modulate cells in adult mice. Re-analysis of existing sequencing data sets of melanocytic cells revealed that genes with a known function in neural cells, including neural stem cells (Aldh1L1 and Nestin), are also expressed in melanocytic cells. Therefore, in this study we explored whether the promoter activity of Nestin and Aldh1L1 can serve to target cells of the melanocyte lineage using the inducible CreER^T2 -loxP-system. Using an immunohistochemical approach and different time-points of analysis, we were able to map the melanocytic fate of recombined stem cells in the adult hair follicle of Nestin-CreER^T2 and Aldh1L1-CreER^T2 transgenic mice. Thus, we here present two new mouse models and propose their use to study and putatively modulate adult melanocytic cells in vivo.

Osteoblastogenesis Alters Small RNA Profiles in EVs Derived from Bone Marrow Stem Cells (BMSCs) and Adipose Stem Cells (ASCs)

Multipotent stem cells (MSCs) are used in various therapeutic applications based on their paracrine secretion activity. Here, we set out to identify and characterize the paracrine factors released during osteoblastogenesis, with a special focus on small non-coding RNAs released in extracellular vesicles (EVs). Bone marrow stem cells (BMSCs) and adipose stem cells (ASCs) from healthy human donors were used as representatives of MSCs. We isolated EVs secreted before and after induction of osteoblastic differentiation and found that the EVs contained a specific subset of microRNAs (miRNAs) and tRNA-derived small RNAs (tsRNA) compared to their parental cells. Osteoblastic differentiation had a larger effect on the small RNA profile of BMSC-EVs relative to ASC-EVs. Our data showed that EVs from different MSC origin exhibited distinct expression profiles of small RNA profiles when undergoing osteoblastogenesis, a factor that should be taken into consideration for stem cell therapy.

A Case of Gastric Amphicrine Signet-Ring Cell Carcinoma

“Amphicrine” (in Greek, amphi- means “both” or “double”) refers to cells that synchronously exhibit the endocrine and exocrine phenotypes. Gastric amphicrine carcinoma is very rare, and only a few case reports are found in the English literature; thus, its pathobiological features remain unclear. Here, we report a case of amphicrine gastric carcinoma. A woman in her sixth decade of life presented with anemia and underwent upper endoscopy, followed by histopathological examination of biopsy specimens. She appeared to have gastric cancer with a tumor measuring 5.0 cm × 4.0 cm in size. Subsequently, the patient underwent total gastrectomy with lymph node dissection. Histopathological examination revealed a poorly cohesive carcinoma that sparsely coexisted with signet-ring cell carcinoma cells with regional lymph node metastasis. Interestingly, synaptophysin immunoreactivity with the coexistence of Alcian blue was found in individual signet-ring cell carcinoma cells. Furthermore, the present amphicrine carcinoma cells immunohistochemically expressed CD44 variant 9, a functional cancer stem cell marker. We believe that the present case findings may support the idea of multipotent stem cells being an origin of amphicrine gastric cancers.

Multipotent versus differentiated cell fate selection in the developing Drosophila airways

Developmental potentials of cells are tightly controlled at multiple levels. The embryonic Drosophila airway tree is roughly subdivided into two types of cells with distinct developmental potentials: a proximally located group of multipotent adult precursor cells (P-fate) and a distally located population of more differentiated cells (D-fate). We show that the GATA-family transcription factor (TF) Grain promotes the P-fate and the POU-homeobox TF Ventral veinless (Vvl/Drifter/U-turned) stimulates the D-fate. Hedgehog and receptor tyrosine kinase (RTK) signaling cooperate with Vvl to drive the D-fate at the expense of the P-fate while negative regulators of either of these signaling pathways ensure P-fate specification. Local concentrations of Decapentaplegic/BMP, Wingless/Wnt, and Hedgehog signals differentially regulate the expression of D-factors and P-factors to transform an equipotent primordial field into a concentric pattern of radially different morphogenetic potentials, which gradually gives rise to the distal-proximal organization of distinct cell types in the mature airway.

DOI:http://dx.doi.org/10.7554/eLife.09646.001

Many organs are composed of tubes of different sizes, shapes and patterns that transport vital substances from one site to another. In the fruit fly species Drosophila melanogaster, oxygen is transported by a tubular network, which divides into finer tubes that allow the oxygen to reach every part of the body.

Different parts of the fruit fly’s airways develop from different groups of tracheal precursor cells. P-fate cells form the most 'proximal' tubes (which are found next to the outer layer of the fly). These cells are 'multipotent' stem cells, and have the ability to specialize into many different types of cells during metamorphosis. The more 'distal' branches that emerge from the proximal tubes develop from D-fate cells. These are cells that generally acquire a narrower range of cell identities.

By performing a genetic analysis of fruit fly embryos, Matsuda et al. have now identified several proteins and signaling molecules that control whether tracheal precursor cells become D-fate or P-fate cells. For example, several signaling pathways work with a protein called Ventral veinless to cause D-fate cells to develop instead of P-fate cells. However, molecules that prevent signaling occurring via these pathways help P-fate cells to form. Different amounts of the molecules that either promote or hinder these signaling processes are present in different parts of the fly embryo; this helps the airways of the fly to develop in the correct pattern.

This work provides a comprehensive view of how cell types with different developmental potentials are positioned in a complex tubular network. This sets a basis for future studies addressing how the respiratory organs – and indeed the entire organism – are sustained.

DOI:http://dx.doi.org/10.7554/eLife.09646.002

Rapid isolation of integrin rich multipotent stem cell pool and reconstruction of mouse epidermis equivalent

We describe here epidermis reconstruction using multipotent mouse epidermal stem cells (EpSCs) enriched from keratinocyte isolates exploting exclusively the stem cell-adhesive property. This method excluded flowcytometry and was swift. Percent enrichment was measured by the uptake of Propidium iodide and Hoechst-33342 dye using flowcytometry to determine EpSCs yield. The sorted cells were characterized by analysis of stem cell markers using immunocytochemistry and immunoblotting techniques. Epidermis was reconstructed using the identified seeding density of EpSCs and the airlift tissue culture. Histology of natural vs reconstructed mammalian epidermis was also compared. Results showed a radical improvement of near 99% in the yield of integrin overexpressing EpSCs. The enriched EpSCs tested positive for biomarkers namely cytokeratin K-15 and, K-14, p63, beta-1-integrin, CD34 and could be passaged for longer durations. Adhesion sorted cells reconstructed the epidermis. The process of tissue reconstruction was faster using the adhesion sorted cells than the FACS sorted EpSCs. The product bioengineered using multipotent EpSCs was histologically similar to normal epidermis. Features like strata basalae, spinosum, granulosum, and corneum were alike real epidermis. The reconstructed epidermis displayed normal homeostasis, which can be considered an approximating actual product for investigative dermatology, toxicology, therapeutic research, regenerative medicine, and tissue engineering.

A double-blind placebo-controlled clinical evaluation of MultiStem for the treatment of ischemic stroke

BACKGROUND

There is growing interest in neurorestorative and reparative therapies after acute stroke. MultiStem is an allogeneic cell therapy treatment comprising a population of multipotent adherent bone marrow cells that has shown safety in clinical trials of myocardial infarction and graft vs. host disease, as well as preclinical evidence of activity in stroke and other neurological damage models. MultiStem is now being evaluated in a clinical trial in patients that have suffered an ischemic stroke, in which the product is administered intravenously 24-36 h after the ischemic event.

METHODS

The Phase 2 randomized, double-blind, placebo-controlled, multicenter dose-escalation trial will consist of three treatment cohorts, including a placebo group, and two treatment groups involving dose tiers of either 400 million or 1200 million cells per patient. Patients will be treated at 24-36 h after stroke. The two primary objectives are to determine the highest well-tolerated and safe single dose of MultiStem up to a maximum of 1200 million total cells in subjects with ischemic stroke and to determine the efficacy of MultiStem on functional outcome in subjects with stroke as measured by the modified Rankin Scale at 90 days. Patients will also be evaluated using the National Institutes of Health Stroke Scale and Barthel Index. The study will explore other aspects including, uniquely, the measurement of spleen size after stroke by magnetic resonance imaging or computed tomography imaging.

CONCLUSIONS AND FUTURE DIRECTION

If MultiStem is safe and there is a signal of efficacy, a late stage phase IIb-III trial is planned.