NK cell-mediated regulation of protective memory responses against intracellular ehrlichial pathogens

Ehrlichiae are gram-negative obligate intracellular bacteria that cause potentially fatal human monocytic ehrlichiosis. We previously showed that natural killer (NK) cells play a critical role in host defense against Ehrlichia during primary infection. However, the contribution of NK cells to the memory response against Ehrlichia remains elusive. Primary infection of C57BL/6 mice with Ehrlichia muris provides long-term protection against a second challenge with the highly virulent Ixodes ovatus Ehrlichia (IOE), which ordinarily causes fatal disease in naïve mice. Here, we show that the depletion of NK cells in E. muris-primed mice abrogates the protective memory response against IOE. Approximately, 80% of NK cell-depleted E. muris-primed mice succumbed to lethal IOE infection on days 8-10 after IOE infection, similar to naïve mice infected with the same dose of IOE. The lack of a recall response in NK cell-depleted mice correlated with an increased bacterial burden, extensive liver injury, decreased frequency of Ehrlichia-specific IFN-γ-producing memory CD4+ and CD8+ T-cells, and a low titer of Ehrlichia-specific antibodies. Intraperitoneal infection of mice with E. muris resulted in the production of IL-15, IL-12, and IFN-γ as well as an expansion of activated NKG2D+ NK cells. The adoptive transfer of purified E. muris-primed hepatic and splenic NK cells into Rag2-/-Il2rg-/-recipient mice provided protective immunity against challenge with E. muris. Together, these data suggest that E. muris-induced memory-like NK cells, which contribute to the protective, recall response against Ehrlichia

How much dystrophin is enough: the physiological consequences of different levels of dystrophin in the mdx mouse

Splice modulation therapy has shown great clinical promise in Duchenne muscular dystrophy, resulting in the production of dystrophin protein. Despite this, the relationship between restoring dystrophin to established dystrophic muscle and its ability to induce clinically relevant changes in muscle function is poorly understood. In order to robustly evaluate functional improvement, we used in situ protocols in the mdx mouse to measure muscle strength and resistance to eccentric contraction-induced damage. Here, we modelled the treatment of muscle with pre-existing dystrophic pathology using antisense oligonucleotides conjugated to a cell-penetrating peptide. We reveal that 15% homogeneous dystrophin expression is sufficient to protect against eccentric contraction-induced injury. In addition, we demonstrate a >40% increase in specific isometric force following repeated administrations. Strikingly, we show that changes in muscle strength are proportional to dystrophin expression levels. These data define the dystrophin restoration levels required to slow down or prevent disease progression and improve overall muscle function once a dystrophic environment has been established in the mdx mouse model

Selective release of muscle-specific, extracellular microRNAs during myogenic differentiation

MyomiRs are muscle-specific microRNAs (miRNAs) that regulate myoblast proliferation and differentiation. Extracellular myomiRs (ex-myomiRs) are highly enriched in the serum of Duchenne Muscular Dystrophy (DMD) patients and dystrophic mouse models and consequently have potential as disease biomarkers. The biological significance of miRNAs present in the extracellular space is not currently well understood. Here we demonstrate that ex-myomiR levels are elevated in perinatal muscle development, during the regenerative phase that follows exercise-induced myoinjury, and concomitant with myoblast differentiation in culture. Whereas ex-myomiRs are progressively and specifically released by differentiating human primary myoblasts and C2C12 cultures, chemical induction of apoptosis in C2C12 cells results in indiscriminate miRNA release. The selective release of myomiRs as a consequence of cellular differentiation argues against the idea that they are solely waste products of muscle breakdown, and suggests they may serve a biological function in specific physiological contexts. Ex-myomiRs in culture supernatant and serum are predominantly non-vesicular, and their release is independent of ceramide-mediated vesicle secretion. Furthermore, ex-myomiRs levels are reduced in aged dystrophic mice, likely as a consequence of chronic muscle wasting. In conclusion, we show that myomiR release accompanies periods of myogenic differentiation in cell culture and in vivo. Serum myomiR abundance is therefore a function of the regenerative/degenerative status of the muscle, overall muscle mass, and tissue expression levels. These findings have implications for the use of ex-myomiRs as biomarkers for DMD disease progression and monitoring response to therapy

The Presence of IL-17A and T Helper 17 Cells in Experimental Mouse Brain Tumors and Human Glioma

Background: Recently, CD4 + IL-17A + T helper 17 (Th17) cells were identified and reported in several diseased states, including autoimmunity, infection and various peripheral nervous system tumors. However, the presence of Th17 in gliaderived tumors of the central nervous system has not been studied. Methodology/Principal Findings: In this report, we demonstrate that mRNA expression for the Th17 cell cytokine IL-17A, as well as Th17 cells, are present in human glioma. The mRNA expression for IL-17A in glioma was recapitulated in an immunocompetent mouse model of malignant glioma. Furthermore, the presence of Th17 cells was confirmed in both human and mouse glioma. Interestingly, some Th17 cells present in mouse glioma co-expressed the Th1 and Th2 lineage markers, IFN-c and IL-4, respectively, but predominantly co-expressed the Treg lineage marker FoxP3. Conclusions: These data confirm the presence of Th17 cells in glia-derived CNS tumors and provide the rationale for further investigation into the role of Th17 cells in malignant glioma

Systemic exosomal siRNA delivery reduced alpha-synuclein aggregates in brains of transgenic mice.

Alpha-synuclein (α-Syn) aggregates are the main component of Lewy bodies, which are the characteristic pathological feature in Parkinson's disease (PD) brain. Evidence that α-Syn aggregation can be propagated between neurones has led to the suggestion that this mechanism is responsible for the stepwise progression of PD pathology. Decreasing α-Syn expression is predicted to attenuate this process and is thus an attractive approach to delay or halt PD progression. We have used α-Syn small interfering RNA (siRNA) to reduce total and aggregated α-Syn levels in mouse brains. To achieve widespread delivery of siRNAs to the brain we have peripherally injected modified exosomes expressing Ravies virus glycoprotein loaded with siRNA. Normal mice were analyzed 3 or 7 days after injection. To evaluate whether this approach can decrease α-Syn aggregates, we repeated the treatment using transgenic mice expressing the human phosphorylation-mimic S129D α-Syn, which exhibits aggregation. In normal mice we detected significantly reduced α-Syn messenger RNA (mRNA) and protein levels throughout the brain 3 and 7 days after treatment with RVG-exosomes loaded with siRNA to α-Syn. In S129D α-Syn transgenic mice we found a decreased α-Syn mRNA and protein levels throughout the brain 7 days after injection. This resulted in significant reductions in intraneuronal protein aggregates, including in dopaminergic neurones of the substantia nigra. This study highlights the therapeutic potential of RVG-exosome delivery of siRNA to delay and reverse brain α-Syn pathological conditions

Etude des dégâts qualitatifs et quantitatifs dus aux Bruches sur les légumineuses au Maroc

Les pertes qualitatives et quantitatives des légumineuses en post-récoltes demeurent un important souci des agriculteurs au Maroc. Les ravageurs de stockage sont l’un des facteurs les plus destructifs des stocks de légumineuses. Pour ce fait, le présent travail porte sur l’identification des différentes espèces d’insectes attaquant les légumineuses stockées au Maroc, et l’évaluation de leurs effets nuisibles sur les pertes en qualité, quantité et faculté germinative des grains. Les résultats mettent en évidence la dominance des coléoptères de la famille Bruchidae, qui attaquent plus de la moitié des quantités stockées surtout pour les cultures de fève et féverole. Les pertes pondérales et le pouvoir germinatif ont aussi été  étudiés. Les résultats ont montré une perte en poids des grains bruchés pouvant aller jusqu’à 34%. Le pouvoir germinatif a été négativement affecté; il a oscillé entre 75 et 85% selon le nombre d’opercule par grain.    

Mesenchymal stem cell-based therapy for ischemic stroke

Ischemic stroke represents a major, worldwide health burden with increasing incidence. Patients affected by ischemic strokes currently have few clinically approved treatment options available. Most currently approved treatments for ischemic stroke have narrow therapeutic windows, severely limiting the number of patients able to be treated. Mesenchymal stem cells represent a promising novel treatment for ischemic stroke. Numerous studies have demonstrated that mesenchymal stem cells functionally improve outcomes in rodent models of ischemic stroke. Recent studies have also shown that exosomes secreted by mesenchymal stem cells mediate much of this effect. In the present review, we summarize the current literature on the use of mesenchymal stem cells to treat ischemic stroke. Further studies investigating the mechanisms underlying mesenchymal stem cells tissue healing effects are warranted and would be of benefit to the field

Isolation of Exosomes from Blood Plasma: Qualitative and Quantitative Comparison of Ultracentrifugation and Size Exclusion Chromatography Methods

BACKGROUND: Exosomes are emerging targets for biomedical research. However, suitable methods for the isolation of blood plasma-derived exosomes without impurities have not yet been described. AIM: Therefore, we investigated the efficiency and purity of exosomes isolated with potentially suitable methods; differential ultracentrifugation (UC) and size exclusion chromatography (SEC). METHODS AND RESULTS: Exosomes were isolated from rat and human blood plasma by various UC and SEC conditions. Efficiency was investigated at serial UC of the supernatant, while in case of SEC by comparing the content of exosomal markers of various fractions. Purity was assessed based on the presence of albumin. We found that the diameter of the majority of isolated particles fell into the size range of exosomes, however, albumin was also present in the preparations, when 1h UC at 4 degrees C was applied. Furthermore, with this method only a minor fraction of total exosomes could be isolated from blood as deduced from the constant amount of exosomal markers CD63 and TSG101 detected after serial UC of rat blood plasma samples. By using UC for longer time or with shorter sedimentation distance at 4 degrees C, or UC performed at 37 degrees C, exosomal yield increased, but albumin impurity was still observed in the isolates, as assessed by transmission electron microscopy, dynamic light scattering and immunoblotting against CD63, TSG101 and albumin. Efficiency and purity were not different in case of using further diluted samples. By using SEC with different columns, we have found that although a minor fraction of exosomes can be isolated without significant albumin content on Sepharose CL-4B or Sephacryl S-400 columns, but not on Sepharose 2B columns, the majority of exosomes co-eluted with albumin. CONCLUSION: Here we show that it is feasible to isolate exosomes from blood plasma by SEC without significant albumin contamination albeit with low vesicle yield

Treg Depletion Inhibits Efficacy of Cancer Immunotherapy: Implications for Clinical Trials

Regulatory T lymphocytes (Treg) infiltrate human glioblastoma (GBM); are involved in tumor progression and correlate with tumor grade. Transient elimination of Tregs using CD25 depleting antibodies (PC61) has been found to mediate GBM regression in preclinical models of brain tumors. Clinical trials that combine Treg depletion with tumor vaccination are underway to determine whether transient Treg depletion can enhance anti-tumor immune responses and improve long term survival in cancer patients.Using a syngeneic intracrabial glioblastoma (GBM) mouse model we show that systemic depletion of Tregs 15 days after tumor implantation using PC61 resulted in a decrease in Tregs present in tumors, draining lymph nodes and spleen and improved long-term survival (50% of mice survived >150 days). No improvement in survival was observed when Tregs were depleted 24 days after tumor implantation, suggesting that tumor burden is an important factor for determining efficacy of Treg depletion in clinical trials. In a T cell dependent model of brain tumor regression elicited by intratumoral delivery of adenoviral vectors (Ad) expressing Fms-like Tyrosine Kinase 3 ligand (Flt3L) and Herpes Simplex Type 1-Thymidine Kinase (TK) with ganciclovir (GCV), we demonstrate that administration of PC61 24 days after tumor implantation (7 days after treatment) inhibited T cell dependent tumor regression and long term survival. Further, depletion with PC61 completely inhibited clonal expansion of tumor antigen-specific T lymphocytes in response to the treatment.Our data demonstrate for the first time, that although Treg depletion inhibits the progression/eliminates GBM tumors, its efficacy is dependent on tumor burden. We conclude that this approach will be useful in a setting of minimal residual disease. Further, we also demonstrate that Treg depletion, using PC61 in combination with immunotherapy, inhibits clonal expansion of tumor antigen-specific T cells, suggesting that new, more specific targets to block Tregs will be necessary when used in combination with therapies that activate anti-tumor immunity

Novel endosomolytic compounds enable highly potent delivery of antisense oligonucleotides

The therapeutic and research potentials of oligonucleotides (ONs) have been hampered in part by their inability to effectively escape endosomal compartments to reach their cytosolic and nuclear targets. Splice-switching ONs (SSOs) can be used with endosomolytic small molecule compounds to increase functional delivery. So far, development of these compounds has been hindered by a lack of high-resolution methods that can correlate SSO trafficking with SSO activity. Here we present in-depth characterization of two novel endosomolytic compounds by using a combination of microscopic and functional assays with high spatiotemporal resolution. This system allows the visualization of SSO trafficking, evaluation of endosomal membrane rupture, and quantitates SSO functional activity on a protein level in the presence of endosomolytic compounds. We confirm that the leakage of SSO into the cytosol occurs in parallel with the physical engorgement of LAMP1-positive late endosomes and lysosomes. We conclude that the new compounds interfere with SSO trafficking to the LAMP1-positive endosomal compartments while inducing endosomal membrane rupture and concurrent ON escape into the cytosol. The efficacy of these compounds advocates their use as novel, potent, and quick-acting transfection reagents for antisense ONs