Inhibition of the CXCL12/CXCR4-Axis as Preventive Therapy for Radiation-Induced Pulmonary Fibrosis

Background

A devastating late injury caused by radiation is pulmonary fibrosis. This risk may limit the volume of irradiation and compromise potentially curative therapy. Therefore, development of a therapy to prevent this toxicity can be of great benefit for this patient population. Activation of the chemokine receptor CXCR4 by its ligand stromal cell-derived factor 1 (SDF-1/CXCL12) may be important in the development of radiation-induced pulmonary fibrosis. Here, we tested whether MSX-122, a novel small molecule and partial CXCR4 antagonist, can block development of this fibrotic process.

Methodology/Principal Findings

The radiation-induced lung fibrosis model used was C57BL/6 mice irradiated to the entire thorax or right hemithorax to 20 Gy. Our parabiotic model involved joining a transgenic C57BL/6 mouse expressing GFP with a wild-type mouse that was subsequently irradiated to assess for migration of GFP+ bone marrow-derived progenitor cells to the irradiated lung. CXCL12 levels in the bronchoalveolar lavage fluid (BALF) and serum after irradiation were determined by ELISA. CXCR4 and CXCL12 mRNA in the irradiated lung was determined by RNase protection assay. Irradiated mice were treated daily with AMD3100, an established CXCR4 antagonist; MSX-122; and their corresponding vehicles to determine impact of drug treatment on fibrosis development. Fibrosis was assessed by serial CTs and histology. After irradiation, CXCL12 levels increased in BALF and serum with a corresponding rise in CXCR4 mRNA within irradiated lungs consistent with recruitment of a CXCR4+ cell population. Using our parabiotic model, we demonstrated recruitment of CXCR4+ bone marrow-derived mesenchymal stem cells, identified based on marker expression, to irradiated lungs. Finally, irradiated mice that received MSX-122 had significant reductions in development of pulmonary fibrosis while AMD3100 did not significantly suppress this fibrotic process.

Conclusions/Significance

CXCR4 inhibition by drugs such as MSX-122 may alleviate potential radiation-induced lung injury, presenting future therapeutic opportunities for patients requiring chest irradiation.     

Smoking and risk of meningioma: A meta-analysis

Objective: The relationship between smoking and the development of meningioma has been investigated in several epidemiological studies. However, the results of these studies are inconsistent. We conducted a meta-analysis in order to identify any potential association. Methods: PubMed, the Cochrane Library, and EMBASE databases were searched to identify relevant articles that investigated the risk of meningioma following cigarette smoking. Two researchers evaluated study eligibility and extracted the data independently, and disagreements were resolved by discussion. The variables used to estimate the pooled risk of smoking in meningioma development were the multivariate-adjusted risk estimates presented in the literature. Results: Seven case–control and two cohort studies were included in this meta-analysis. The pooled estimated risks associated with ever smoking for meningioma were 1.02 (95% confidence interval (CI): 0.85–1.21) in the case–control studies, 0.93 (95% CI: 0.83–1.04) in the cohort studies and 0.95 (95% CI: 0.87–1.05, P = 0.32) in all studies when the cohort and case–control data were combined. Subgroup analyses suggested that the risk estimates were 1.49 (95% CI: 1.06–2.09, P = 0.02), 0.86 (95% CI: 0.65–1.13), 0.79 (95% CI: 0.50–1.25) and 0.84 (95% CI: 0.69–1.03) for men, women, current and past smoking respectively. Sensitivity analyses restricted to studies with different adjustments for confounders yielded similar results. No evidence of publication bias was observed. Conclusion: Our meta-analysis suggests that there is no association between ever smoking and the risk of meningioma. However, a small but significant risk elevation is present among men smokers.     

The institute for genomic research Osa1 rice genome annotation database

We have developed a rice (Oryza sativa) genome annotation database (Osa1) that provides structural and functional annotation for this emerging model species. Using the sequence of O. sativa subsp. japonica cv Nipponbare from the International Rice Genome Sequencing Project, pseudomolecules, or virtual contigs, of the 12 rice chromosomes were constructed. Our most recent release, version 3, represents our third build of the pseudomolecules and is composed of 98% finished sequence. Genes were identified using a series of computational methods developed for Arabidopsis (Arabidopsis thaliana) that were modified for use with the rice genome. In release 3 of our annotation, we identified 57,915 genes, of which 14,196 are related to transposable elements. Of these 43,719 non-transposable element-related genes, 18,545 (42.4%) were annotated with a putative function, 5,777 (13.2%) were annotated as encoding an expressed protein with no known function, and the remaining 19,397 (44.4%) were annotated as encoding a hypothetical protein. Multiple splice forms (5,873) were detected for 2,538 genes, resulting in a total of 61,250 gene models in the rice genome. We incorporated experimental evidence into 18,252 gene models to improve the quality of the structural annotation. A series of functional data types has been annotated for the rice genome that includes alignment with genetic markers, assignment of gene ontologies, identification of flanking sequence tags, alignment with homologs from related species, and syntenic mapping with other cereal species. All structural and functional annotation data are available through interactive search and display windows as well as through download of flat files. To integrate the data with other genome projects, the annotation data are available through a Distributed Annotation System and a Genome Browser. All data can be obtained through the project Web pages at http://rice.tigr.org.     

Wnt/beta-catenin signaling acts upstream of N-myc, BMP4, and FGF signaling to regulate proximal-distal patterning in the lung

Branching morphogenesis in the lung serves as a model for the complex patterning that is reiterated in multiple organs throughout development. Beta-catenin and Wnt signaling mediate critical functions in cell fate specification and differentiation, but specific functions during branching morphogenesis have remained unclear. Here, we show that Wnt/beta-catenin signaling regulates proximal-distal differentiation of airway epithelium. Inhibition of Wnt/beta-catenin signaling, either by expression of Dkk1 or by tissue-specific deletion of beta-catenin, results in disruption of distal airway development and expansion of proximal airways. Wnt/beta-catenin functions upstream of BMP4, FGF signaling, and N-myc. Moreover, we show that beta-catenin and LEF/TCF activate the promoters of BMP4 and N-myc. Thus, Wnt/beta-catenin signaling is a critical upstream regulator of proximal-distal patterning in the lung, in part, through regulation of N-myc, BMP4, and FGF signaling.     

Distinct immunologic specificity of tumor regression mediated by effector cells isolated from immunized and tumor-bearing mice

Sensitized T lymphocytes can mediate potent antitumor effects when transferred to tumor-bearing animals. Employing the MCA 105 and MCA 106 sarcomas, we were able to generate antitumor effector cells by immunization of syngeneic mice with tumor cells admixed with Corynebacterium parvum. These immune splenocytes could be further sensitized and expanded in culture by the in vitro sensitization (IVS) method utilizing tumor stimulator cells and IL-2. Adoptive immunotherapy of pulmonary metastases mediated by noncultured splenocytes from immunized mice or immune IVS cells showed exquisite specificity between the two sarcomas. These results demonstrate the presence of tumor-specific antigens on MCA 105 and MCA 106 tumor cells which can serve as target molecules for immunotherapy. Recently, we have generated therapeutic T lymphocytes from mice bearing progressively growing tumors by the IVS method. However, IVS cells from tumor-bearing mice showed cross-reactivity between the MCA 105 and 106 sarcomas in adoptive immunotherapy experiments. Since these IVS cells did not affect other control tumors, the limited cross-reactivity suggests the presence of common tumor-associated antigens on MCA 105 and MCA 106 tumor cells which can also serve as the target for tumor rejection. Therefore, immune responses to progressive tumor growth and to immunization are distinct with respect to antigen recognition by T lymphocytes.     

Elicitation of immunity in mice after immunization with the S2 subunit of the severe acute respiratory syndrome coronavirus

The S2 domain of the severe acute respiratory syndrome coronavirus (SARS-CoV) spike (S) protein is responsible for fusion between virus and target cell membranes, and is expected to be immungenic. In this study, we investigated the immune responses against the S2 subunit in BALB/c mice, which were vaccinated either with plasmid DNA encoding the S2 domain (residues 681-1120), the recombinant S2 fragment (residues 681-980) in incomplete Freund's adjuvant, or with inactivated SARS-CoV. The increased number of specific cytotoxic cells (CTLs) and the high titer of specific antibody showed stimulation of both arms of the immune system in these groups. The shift in cytokines suggested that Th1-polarized immune response was induced by plasmid pCoVS2, meanwhile the Th2-dominant response was induced by recombinant S2 fragment and inactivated vaccine. However, the titer of neutralizing antibodies was only detectable in mice immunized with inactivated virus, but not with pCoVS2 plasmid. Taken together, the S2 domain could induce specific cellular immune response and a high level of total IgG but little neutralizing antibodies against infection by SARSCoV.     

siRNA, miRNA and HIV: promises and challenges

Small interfering RNA (siRNA) and microRNA (miRNA) are small RNAs of 18-25 nucleotides (nt) in length that play important roles in regulating gene expression. They are incorporated into an RNA-induced silencing complex (RISC) and serve as guides for silencing their corresponding target mRNAs based on complementary base-pairing. The promise of gene silencing has led many researchers to consider siRNA as an anti-viral tool. However, in long-term settings, many viruses appear to escape from this therapeutical strategy. An example of this may be seen in the case of human immunodeficiency virus type-1 (HIV-1) which is able to evade RNA silencing by either mutating the siRNA-targeted sequence or by encoding for a partial suppressor of RNAi (RNA interference). On the other hand, because miRNA targeting does not require absolute complementarity of base-pairing, mutational escape by viruses from miRNA-specified silencing may be more difficult to achieve. In this review, we discuss stratagems used by various viruses to avoid the cells' antiviral si/mi-RNA defenses and notions of how viruses might control and regulate host cell genes by encoding viral miRNAs (vmiRNAs).     

GH-releasing peptides improve cardiac dysfunction and cachexia and suppress stress-related hormones and cardiomyocyte apoptosis in rats with heart failure

Growth hormone (GH)-releasing peptides (GHRP), a class of synthetic peptidyl GH secretagogues, have been reported to exert a cardioprotective effect on cardiac ischemia. However, whether GHRP have a beneficial effect on chronic heart failure (CHF) is unclear, and the present work aims to clarify this issue. At 9 wk after pressure-overload CHF was created by abdominal aortic banding in rats, one of four variants of GHRP (GHRP-1, -2, and -6 and hexarelin, 100 mug/kg) or saline was injected subcutaneously twice a day for 3 wk. Echocardiography and cardiac catheterization were performed to monitor cardiac function and obtain blood samples for hormone assay. GHRP treatment significantly improved left ventricular (LV) function and remodeling in CHF rats, as indicated by increased LV ejection fraction, LV end-systolic pressure, and diastolic posterior wall thickness and decreased LV end-diastolic pressure and LV end-diastolic dimension. GHRP also significantly alleviated development of cardiac cachexia, as shown by increases in body weight and tibial length in CHF rats. Plasma CA, renin, ANG II, aldosterone, endothelin-1, and atrial natriuretic peptide were significantly elevated in CHF rats but were significantly decreased in GHRP-treated CHF rats. GHRP suppressed cardiomyocyte apoptosis and increased cardiac GH secretagogue receptor mRNA expression in CHF rats. GHRP also decreased myocardial creatine kinase release in hypophysectomized rats subjected to acute myocardial ischemia. We conclude that chronic administration of GHRP alleviates LV dysfunction, pathological remodeling, and cardiac cachexia in CHF rats, at least in part by suppressing stress-induced neurohormonal activations and cardiomyocyte apoptosis.     

Study on the interaction between pelargonidin‐3‐O‐glucoside and bovine serum albumin using spectroscopic,transmission electron microscopy and molecular modeling techniques

The aim of this study is to evaluate the binding behavior between pelargonidin‐3‐O‐glucoside (P3G) and bovine serum albumin (BSA) using multi‐spectroscopic, transmission electron microscopy (TEM) and molecular docking methods under physiological conditions. Fluorescence spectroscopy and time‐resolved fluorescence showed that the fluorescence of BSA could be quenched remarkably by P3G via a static quenching mechanism, and there is a single class of binding site on BSA. In addition, the thermodynamic functions ΔH and ΔS were –21.69 kJ/mol and 24.46 J/mol/K, indicating that an electrostatic interaction was a main acting force. The distance between BSA and P3G was 2.74 nm according to Förster's theory, illustrating that energy transfer occurred. In addition, the secondary structure of BSA changed with a decrease in the α‐helix content from 66.2% to 64.0% as seen using synchronous fluorescence, UV/vis, circular dichroism and Fourier transform infrared spectroscopies, whereas TEM images showed that P3G led to BSA aggregation and fibrillation. Furthermore, site marker competitive experiments and molecular docking indicated that P3G could bind with subdomain IIA of BSA. The calculated results of the equilibrium fraction showed that the concentration of free P3G in plasma was high enough to be stored and transported from the circulatory system to its target sites to provide therapeutic effects. Copyright © 2015 John Wiley & Sons, Ltd.