Encephalitogenic T cells that mediate experimental autoimmune encephalomyelitis (EAE) are commonly assumed to be exclusively CD4+, but formal proof is still lacking. In this study, we report that synthetic peptides 35–55 from myelin oligodendrocyte glycoprotein (pMOG35–55) consistently activate a high proportion of CD8+ αβTCR+ T cells that are encephalitogenic in C57BL/6 (B6) mice. The encephalitogenic potential of CD8+ MOG-specific T cells was established by adoptive transfer of CD8-enriched MOG-specific T cells. These cells induced a much more severe and permanent disease than disease actively induced by immunization with pMOG35–55. CNS lesions in pMOG35–55 CD8+ T cell-induced EAE were progressive and more destructive. The CD8+ T cells were strongly pathogenic in syngeneic B6 and RAG-1−/− mice, but not in isogeneic β2-microglobulin-deficient mice. MOG-specific CD8+ T cells could be repeatedly reisolated for up to 287 days from recipient B6 or RAG-1−/− mice in which disease was induced adoptively with <1 × 106 T cells sensitized to pMOG35–55. It is postulated that MOG induces a relapsing and/or progressive pattern of EAE by eliciting a T cell response dominated by CD8+ autoreactive T cells. Such cells appear to have an enhanced tissue-damaging effect and persist in the animal for long periods.

Extrachromosomal circular DNA elements (EccDNAs) have been described in the literature for several decades, and are known for their broad existence across different species 1 , 2 . However, their biogenesis, and functions are largely unknown. By developing a new circular DNA enrichment method, here we purified, and sequenced full-length eccDNAs with Nanopore sequencing. We found that eccDNAs are mapped across the entire genome in a close to random fashion, suggesting a biogenesis mechanism of random ligation of genomic DNA fragments. Consistently, we found that apoptosis inducers can increase eccDNA generation, which is dependent on apoptotic DNA fragmentation followed by ligation by the DNA ligase 3. Importantly, we demonstrated that eccDNAs can function as potent innate immunostimulants in a sequence-independent, but circularity, and cytosolic DNA sensing Sting-dependent fashion. Collectively, our study not only revealed the origin, biogenesis, and immunostimulant function of eccDNAs, but also uncovered their sensing pathway and potential clinical implications in immune response.

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A major problem associated with adenovirus gene therapy is the T cell-mediated immune response, which is elicited by inoculation of the adenovirus vector and leads to rapid clearance of the virus and loss of transgene expression. In this study, the immune response to adenovirus was prevented by induction of specific T-cell tolerance by pretreatment with adenovirus-infected antigen-presenting cells (APC) that express Fas ligand. Compared with control-treated mice, the tolerized mice showed prolonged expression of lacZ upon administration of AdCMVlacZ 1 week after tolerance induction. In contrast to the control mice, the tolerized mice did not display proliferation of CD3+ T cells in the spleen in response to AdCMVlacZ. Tolerance induction also was indicated by the lower production of interferon-gamma and interleukin-2 by peripheral T cells isolated from AdCMVlacZ-challenged tolerized mice than by AdCMVlacZ-challenged control-treated mice. The T-cell tolerance was specific for the adenovirus as the T-cell responses to irrelative murine cytomegalovirus remained unimpaired. Our results indicate that adenovirus-specific T-cell tolerance can be induced by APCs that coexpress Fas ligand and adenovirus antigens. We propose that this new strategy can be used to induce tolerance to adenovirus vector gene therapy with resultant prolonged expression of the transgene.

No abstract

We report the construction of periodic DNA nanoribbons (DNRs) by a modified DNA origami method. Unlike the conventional DNA origami, the DNR scaffold is a long, single-stranded DNA of tandem repeats, originating from the rolling circular amplification (RCA). Consequently, the number of folding staple strands tremendously decreases from hundreds to a few, which makes the DNR production scalable and cost-effective, thus potentially removing the barrier for practical applications of DNA nanostructures. Moreover, the co-replicational synthesis of scaffold and staple strands by RCA-based enzymatic reactions allows the generation of DNRs in one pot, further reducing the cost. Due to their unique periodicity, rigidity, and high aspect ratio, DNRs are efficiently internalized into cells and escape from endosomal entrapment, making them potential nanocarriers for imaging agents and biological therapeutics. We demonstrated proof-of-concept applications of DNRs as an intracellular pH sensor and an efficient small interfering RNA delivery vehicle in human cancer cells.

Programmed self-assembly of nucleic acids is a powerful approach for nano-constructions. The assembled nanostructures have been explored for various applications. However, nucleic acid assembly often requires chemical or in vitro enzymatical synthesis of DNA or RNA, which is not a cost-effective production method on a large scale. In addition, the difficulty of cellular delivery limits the in vivo applications. Herein we report a strategy that mimics protein production. Gene-encoded DNA duplexes are transcribed into single-stranded RNAs, which self-fold into well-defined RNA nanostructures in the same way as polypeptide chains fold into proteins. The resulting nanostructure contains only one component RNA molecule. This approach allows both in vitro and in vivo production of RNA nanostructures. In vivo synthesized RNA strands can fold into designed nanostructures inside cells. This work not only suggests a way to synthesize RNA nanostructures on a large scale and at a low cost but also facilitates the in vivo applications.

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