Transcriptional profiling in C-elegans suggests DNA damage dependent apoptosis as an ancient function of the p53 family

Background: In contrast to the three mammalian p53 family members, p53, which is generally involved in DNA damage responses, and p63 and p73 which are primarily needed for developmental regulation, cep-1 encodes for the single C. elegans p53-like gene. cep-1 acts as a transcription activator in a primordial p53 pathway that involves CEP-1 activation and the CEP-1 dependent transcriptional induction of the worm BH3 only domain encoding genes egl-1 and ced-13 to induce germ cell apoptosis. EGL-1 and CED-13 proteins inactivate Bcl-2 like CED-9 to trigger CED-4 and CED-3 caspase dependent germ cell apoptosis. To address the function of p53 in global transcriptional regulation we investigate genome-wide transcriptional responses upon DNA damage and cep-1 deficiency. Results: Examining C. elegans expression profiles using whole genome Affymetrix GeneChip arrays, we found that 83 genes were induced more than two fold upon ionizing radiation (IR). None of these genes, with exception of an ATP ribosylase homolog, encode for known DNA repair genes. Using two independent cep-1 loss of function alleles we did not find genes regulated by cep-1 in the absence of IR. Among the IR-induced genes only three are dependent on cep-1, namely egl-1, ced-13 and a novel C. elegans specific gene. The majority of IR-induced genes appear to be involved in general stress responses, and qRT-PCR experiments indicate that they are mainly expressed in somatic tissues. Interestingly, we reveal an extensive overlap of gene expression changes occurring in response to DNA damage and in response to bacterial infection. Furthermore, many genes induced by IR are also transcriptionally regulated in longevity mutants suggesting that DNA damage and aging induce an overlapping stress response. Conclusion: We performed genome-wide gene expression analyses which indicate that only a surprisingly small number of genes are regulated by CEP-1 and that DNA damage induced apoptosis via the transcriptional induction of BH3 domain proteins is likely to be an ancient DNA damage response function of the p53 family. Interestingly, although the apoptotic response to DNA damage is regulated through the transcriptional activity of CEP-1, other DNA damage responses do not appear to be regulated on the transcriptional level and do not require the p53 like gene cep-1

A Small-Molecule Screen for Enhanced Homing of Systemically Infused Cells

Poor homing of systemically infused cells to disease sites may limit the success of exogenous cell-based therapy. In this study, we screened 9,000 signal-transduction modulators to identify hits that increase mesenchymal stromal cell (MSC) surface expression of homing ligands that bind to intercellular adhesion molecule 1 (ICAM-1), such as CD11a. Pretreatment of MSCs with Ro-31-8425, an identified hit from this screen, increased MSC firm adhesion to an ICAM-1-coated substrate in vitro and enabled targeted delivery of systemically administered MSCs to inflamed sites in vivo in a CD11a- (and other ICAM-1-binding domains)-dependent manner. This resulted in a heightened anti-inflammatory response. This represents a new strategy for engineering cell homing to enhance therapeutic efficacy and validates CD11a and ICAM-1 as potential targets. Altogether, this multi-step screening process may significantly improve clinical outcomes of cell-based therapies

A cell-based drug delivery platform for treating central nervous system inflammation

Mesenchymal stem cells (MSCs) are promising candidates for the development of cell-based drug delivery systems for autoimmune inflammatory diseases, such as multiple sclerosis (MS). Here, we investigated the effect of Ro-31-8425, an ATP-competitive kinase inhibitor, on the therapeutic properties of MSCs. Upon a simple pretreatment procedure, MSCs spontaneously took up and then gradually released significant amounts of Ro-31-8425. Ro-31-8425 (free or released by MSCs) suppressed the proliferation of CD4+ T cells in vitro following polyclonal and antigen-specific stimulation. Systemic administration of Ro-31-8425-loaded MSCs ameliorated the clinical course of experimental autoimmune encephalomyelitis (EAE), a murine model of MS, displaying a stronger suppressive effect on EAE than control MSCs or free Ro-31-8425. Ro-31-8425-MSC administration resulted in sustained levels of Ro-31-8425 in the serum of EAE mice, modulating immune cell trafficking and the autoimmune response during EAE. Collectively, these results identify MSC-based drug delivery as a potential therapeutic strategy for the treatment of autoimmune diseases.National Institutes of Health (Grant HL095722

Therapeutic administration of a recombinant human monoclonal antibody reduces the severity of chikungunya virus disease in rhesus macaques

<div><p>Chikungunya virus (CHIKV) is a mosquito-borne virus that causes a febrile syndrome in humans associated with acute and chronic debilitating joint and muscle pain. Currently no licensed vaccines or therapeutics are available to prevent or treat CHIKV infections. We recently isolated a panel of potently neutralizing human monoclonal antibodies (mAbs), one (4N12) of which exhibited prophylactic and post-exposure therapeutic activity against CHIKV in immunocompromised mice. Here, we describe the development of an engineered CHIKV mAb, designated SVIR001, that has similar antigen binding and neutralization profiles to its parent, 4N12. Because therapeutic administration of SVIR001 in immunocompetent mice significantly reduced viral load in joint tissues, we evaluated its efficacy in a rhesus macaque model of CHIKV infection. Rhesus macaques that were treated after infection with SVIR001 showed rapid elimination of viremia and less severe joint infiltration and disease compared to animals treated with SVIR002, an isotype control mAb. SVIR001 reduced viral burden at the site of infection and at distant sites and also diminished the numbers of activated innate immune cells and levels of pro-inflammatory cytokines and chemokines. SVIR001 therapy; however, did not substantively reduce the induction of CHIKV-specific B or T cell responses. Collectively, these results show promising therapeutic activity of a human anti-CHIKV mAb in rhesus macaques and provide proof-of-principle for its possible use in humans to treat active CHIKV infections.</p></div

Histological findings in joint tissues at 7 dpi.

<p>Histological findings in joint tissues at 7 dpi.</p

CHIKV mAb treatment did not cause significant changes in CD4⁺ or CD8⁺ T cell proliferation.

<p>Rhesus macaques were inoculated with CHIKV and treated with control antibody SVIR002 or CHIKV mAb SVIR001. Blood was drawn daily 0–7 dpi, and PBMCs were examined for proliferative responses of different <b>(A-C)</b> CD4⁺ and <b>(D-F)</b> CD8⁺ T cell subsets. T cell subsets were defined in <b><a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005637#pntd.0005637.s002" target="_blank">S2 Fig</a></b> as Naïve (NV), Central Memory (CM), and Effector Memory (EM). The Ki67⁺ proliferative status was plotted as a percentage of the total population. <b>(G)</b> IFNγ ELISpot analysis was performed on PBMCs from rhesus macaques at 7 dpi. PBMCs from animals treated with SVIR001 (5 mg/kg or 15 mg/kg) or SVIR002 (15 mg/kg) were stimulated with CHIKV peptide pools (10 μg/well), inactivated CHIKV (iCHIKV) (10 μg/well), or PMA/Ionomycin as a positive control. DMSO was used as a negative control to establish the baseline number of IFNγ-producing T cells for each animal. Spots were quantified on an AID ELISpot plate reader (n = 4/group).</p

Tissue viral load following CHIKV mAb therapy.

<p>Animals were euthanized at day 7 post-infection, and viral RNA was isolated from tissues and quantified by qRT-PCR. The viral load in <b>(A)</b> arm joints and muscles, <b>(B)</b> leg joints and muscles, and <b>(C)</b> lymphoid tissues, heart and kidney are reported. Statistical significance was determined on the log-transformed data using Dunnett’s multiple comparison test, and multiplicity-adjusted <i>P</i> values are reported (n = 4; ** <i>P</i> < 0.005, * <i>P</i> < 0.05).</p