Toxoplasma gondii GRA28 Is Required for Placenta-Specific Induction of the Regulatory Chemokine CCL22 in Human and Mouse

Toxoplasma gondii is a globally ubiquitous pathogen that can cause severe disease in HIV/AIDS patients and can also cross the placenta and infect the developing fetus. We have found that placental and immune cells infected with T. gondii secrete significant amounts of a chemokine (called CCL22) that is critical for immune tolerance during pregnancy.

RNAa-Mediated Epigenetic Attenuation of The Cell Senescence via Locus Specific Induction of Endogenous SIRT1

SIRT1, a known regulator of cellular senescence, is a therapeutic target for age related disorders and its upregulation is a strategy to improve the cell therapeutic potentials of human mesenchymal stem cell (MSCs). Knockdown of natural antisense transcripts via small activating RNAs (RNAa) is an emerging approach for safe and locus specific gene regulation. We have recently identified a natural antisense transcript at human SIRT1 locus (SIRT1-NAT), the expression of which shows a negative correlation with that of SIRT1. To test the hypothetic upregulation of SIRT1 via knockdown of SIRT1-NAT, in this study we designed a single stranded oligonucleotide (SIRT1-antagoNAT) against the antisense transcript, transfection of which efficiently knocked down the SIRT1-NAT and induced SIRT1 transcription in human MSCs. In addition, activation of SIRT1 transfection via knockdown of SIRT1-NAT in human MSCs enhanced their proliferation and differentiation potentials, reduced senescence associated β-galactosidase activity and reversed the senescence associated molecular alterations. Our findings introduce an RNAa mediated approach for epigenetic induction of endogenous SIRT1 and the consequent attenuation of senescence. Further studies should evaluate the therapeutic potentials of this approach against various age related disorders.

Optogenetic activators of apoptosis, necroptosis and pyroptosis for probing cell death dynamics and bystander cell responses

Targeted and specific induction of cell death in individual or groups of cells holds the potential for new insights into the response of tissues or organisms to different forms of death. Here we report the development of optogenetically-controlled cell death effectors (optoCDEs), a novel class of optogenetic tools that enables light-mediated induction of three types of programmed cell death (PCD) – apoptosis, pyroptosis and necroptosis – using Arabidopsis thaliana photosensitive protein Cryptochrome2. OptoCDEs enable rapid and highly specific induction of PCD in human, mouse and zebrafish cells and are suitable for a wide range of applications, such as sub-lethal cell death induction or precise elimination of single cells or cell populations in vitro and in vivo. As the proof-of-concept, we utilize optoCDEs to assess the differences in the neighboring cell response to apoptotic or necrotic PCD, revealing a new role for shingosine-1-phosphate signaling in regulating the efferocytosis of apoptotic cell by epithelia.

Antigen-Specific Treg Therapy in Type 1 Diabetes – Challenges and Opportunities

Regulatory T cells (Tregs) are key mediators of peripheral self-tolerance and alterations in their frequencies, stability, and function have been linked to autoimmunity. The antigen-specific induction of Tregs is a long-envisioned goal for the treatment of autoimmune diseases given reduced side effects compared to general immunosuppressive therapies. However, the translation of antigen-specific Treg inducing therapies for the treatment or prevention of autoimmune diseases into the clinic remains challenging. In this mini review, we will discuss promising results for antigen-specific Treg therapies in allergy and specific challenges for such therapies in autoimmune diseases, with a focus on type 1 diabetes (T1D). We will furthermore discuss opportunities for antigen-specific Treg therapies in T1D, including combinatorial strategies and tissue-specific Treg targeting. Specifically, we will highlight recent advances in miRNA-targeting as a means to foster Tregs in autoimmunity. Additionally, we will discuss advances and perspectives of computational strategies for the detailed analysis of tissue-specific Tregs on the single-cell level.

A Novel mRNA-Mediated and MicroRNA-Guided Approach to Specifically Eradicate Drug-Resistant Hepatocellular Carcinoma Cell Lines by Se-Methylselenocysteine

Despite progress in the treatment of non-visceral malignancies, the prognosis remains poor for malignancies of visceral organs and novel therapeutic approaches are urgently required. We evaluated a novel therapeutic regimen based on treatment with Se-methylselenocysteine (MSC) and concomitant tumor-specific induction of Kynurenine aminotransferase 1 (KYAT1) in hepatocellular carcinoma (HCC) cell lines, using either vector-based and/or lipid nanoparticle-mediated delivery of mRNA. Supplementation of MSC in KYAT1 overexpressed cells resulted in significantly increased cytotoxicity, due to ROS formation, as compared to MSC alone. Furthermore, microRNA antisense-targeted sites for miR122, known to be widely expressed in normal hepatocytes while downregulated in hepatocellular carcinoma, were added to specifically limit cytotoxicity in HCC cells, thereby limiting the off-target effects. KYAT1 expression was significantly reduced in cells with high levels of miR122 supporting the concept of miR-guided induction of tumor-specific cytotoxicity. The addition of alpha-ketoacid favored the production of methylselenol, enhancing the cytotoxic efficacy of MSC in HCC cells, with no effects on primary human hepatocytes. Altogether, the proposed regimen offers great potential to safely and specifically target hepatic tumors that are currently untreatable.

Gene expression in Lucilia sericata (Diptera: Calliphoridae) larvae exposed to Pseudomonas aeruginosa and Acinetobacter baumanii identifies shared and microbe-specific induction of immune genes

Antibiotic resistance is a continuing challenge in medicine. There are various strategies for expanding antibiotic therapeutic repertoires, including the use of blow flies. Their larvae exhibit strong antibiotic and antibiofilm properties that alter microbiome communities. One species, Lucilia sericata, is used to treat problematic wounds due to its debridement capabilities and its excretions and secretions that kill some pathogenic bacteria. There is much to be learned about how L. sericata interacts with microbiomes at the molecular level. To address this deficiency, gene expression was assessed after feeding exposure (1 hour or 4 hours) to two clinically problematic pathogens: Pseudomonas aeruginosa and Acinetobacter baumanii. The results identified immunity related genes that were differentially expressed when exposed to these pathogens, as well as non-immune genes possibly involved in gut responses to bacterial infection. There was a greater response to P. aeruginosa that increased over time, while few genes responded to A. baumanii exposure and expression was not time-dependent. The response to feeding on pathogens indicates a few common responses and features distinct to each pathogen, which is useful in improving wound debridement therapy and helps develop biomimetic alternatives.

Targeted enzyme assisted chemotherapy (TEAC) – a novel microRNA-guided and selenium-based regimen to specifically eradicate hepatocellular carcinoma

Despite progress in the treatment of non-visceral malignancies, the prognosis remains poor for malignancies of visceral organs and novel therapeutic approaches are urgently required. Here we introduce a novel therapeutic regimen by treatment with Se-methylselenocysteine (MSC) and concomitant tumor-specific induction of Kynurenine aminotransferase 1 (KYAT1) in hepatocellular carcinoma (HCC) cell lines, using either vector-based and/or lipid nanoparticle-mediated delivery of mRNA. Supplementation of MSC in KYAT1 overexpressed cells resulted in significantly increased cytotoxicity as compared to MSC alone. Furthermore, microRNA antisense targeted sites for miR122, known to be widely expressed in normal hepatocytes whilst downregulated in hepatocellular carcinoma, were added to specifically limit cytotoxicity in HCC cells, thereby limiting off-target effects. KYAT1 expression was significantly reduced in cells with high levels of miR122 supporting the concept of miR-guided induction of tumor-specific cytotoxicity. The addition of alpha-ketoacid favored the production of methylselenol, enhancing the cytotoxic efficacy of MSC in HCC cells, with no effects on primary human hepatocytes. Altogether, the proposed regimen offers great potential to safely and specifically target hepatic tumors that are currently untreatable.