Innate immune responses in patients treated with SBRT irradiation enhances prostate cancer remissions

Stereotactic body radiation therapy (SBRT) is a curative therapeutic modality employing large fractional doses of highly conformal radiation therapy for cancer treatment. To understand the mechanisms underlying clinical responses to radiation therapy, SBRT offers a unique window for high-throughput analysis of post-radiation molecular events to inform predictive biomarker discovery and strategies for multi-disciplinary therapeutics. We performed a longitudinal analysis of plasma proteins and metabolites from patients treated with prostate SBRT, comparing cohorts of patients in clinical remission to cohorts experiencing PSA-determined cancer progression. We observed the onset of post-SBRT DNA Damage Response (DDR), cell cycle arrest, and immune response signaling in patients within one hour of treatment and innate immune response signaling that persisted for up to three months following treatment. Furthermore, patients in remission experienced more robust immune responses and metabolite elevations consistent with a pro-inflammatory, M1-mediated innate immune activation in the short-term following SBRT, whereas patients with disease progression had less robust immune responses and M2-mediated metabolite elevations. We interpret these data to support a critical role for innate immune activation in the clinical outcomes of patients receiving radiation therapy for prostate cancer potentially improving future multidisciplinary therapeutic strategies.

Mechanism Driven Early Stage Identification and Avoidance of Antisense Oligonucleotides Causing TRL9 Mediated Inflammatory Responses in Bjab cells

Nucleic acid-based PS-ASOs have the potential to activate cellular innate immune responses, and the level of activation can vary quite dramatically with sequence. Minimizing degree of proinflammatory effect is one of the main selection criteria for compounds intended to move into clinical trials. While a recently developed hPBMC-based assay showed excellent ability to detect innate immune active PS-ASOs, which can then be discarded from the developmental process, this assay is highly resource-intensive and easily affected by subject variability. This compelled us to develop of a more convenient high-throughput assay. Here, we describe a new in vitro assay, utilizing a cultured human Bjab cell line, which was developed and validated to identify PS-ASOs that may cause innate immune activation. The assay was calibrated to replicate results from the hPMBC assay. The Bjab assay was designed to be high throughput and more convenient by using RT-qPCR readout of mRNA of the chemokine Ccl22. The Bjab assay was also shown to be highly reproducible and to provide a large dynamic range in determining the immune potential of PS-ASOs via comparison to known benchmark PS-ASO controls that were previously shown to be either safe or inflammatory in clinical trials. In addition, we demonstrate that Bjab cells can be used to provide mechanistic information on PS-ASO-TLR9 dependent innate immune activation.

The Astrocyte Type I Interferon Response is Essential for Protection Against Herpes Simplex Encephalitis

Innate immune activation by central nervous system (CNS) resident cells is critical for controlling HSV-1 replication.…

Toll-Like Receptor (TLR) Signaling Enables Cyclic GMP-AMP Synthase (cGAS) Sensing of HIV-1 Infection in Macrophages

Innate immune activation is a hallmark of HIV-1 pathogenesis. Thus, it is critical to understand how HIV-1 infection elicits innate immune responses.

BST2 suppresses LINE-1 retrotransposition by reducing the promoter activity of LINE-1 5′-UTR

Endogenous retrotransposons are considered the “molecular fossils” of ancient retroviral insertions. Several studies have indicated that host factors restrict both retroviruses and retrotransposons through different mechanisms. Type 1 long interspersed elements (LINE-1 or L1) are the only active retroelements that can replicate autonomously in the human genome. A recent study reported that LINE-1 retrotransposition is potently suppressed by BST2, a host restriction factor that prevents viral release mainly by physically tethering enveloped virions (such as human immunodeficiency virus [HIV]) to the surface of producer cells. However, no endoplasmic membrane structure has been associated with LINE-1 replication, suggesting that BST2 may utilize a distinct mechanism to suppress LINE-1. In this study, we showed that BST2 is a potent LINE-1 suppressor. Further investigations suggested that BST2 reduces the promoter activity of LINE-1 5’-UTR and lowers the levels of LINE-1 RNA, proteins, and events during LINE-1 retrotransposition. Surprisingly, although BST2 apparently uses different mechanisms against HIV and LINE-1, two membrane-associated domains that are essential for BST2-mediated HIV tethering also proved important for BST2-induced inhibition of LINE-1 5’-UTR. Additionally, by suppressing LINE-1, BST2 prevented LINE-1-induced genomic DNA damage and innate immune activation. Taken together, our data uncovered the mechanism of BST2-mediated LINE-1 suppression and revealed new roles of BST2 as a promoter regulator, genome stabilizer, and innate immune suppressor. IMPORTANCE BST2 is a potent antiviral protein that suppresses the release of several enveloped viruses, mainly by tethering the envelope of newly synthesized virions and restraining them on the surface of producer cells. In mammalian cells, there are numerous DNA elements replicating through reverse transcription, among which LINE-1 is the only retroelement that can replicate autonomously. Although LINE-1 retrotransposition does not involve the participation of a membrane structure, BST2 has been reported as an efficient LINE-1 suppressor, suggesting a different mechanism for BST2-mediated LINE-1 inhibition and a new function for BST2 itself. We found that BST2 specifically represses the promoter activity of LINE-1 5’-UTR, resulting in decreased levels of LINE-1 transcription, translation, and subsequent retrotransposition. Additionally, by suppressing LINE-1 activity, BST2 maintains genome stability and regulates innate immune activation. These findings expand our understanding of BST2 and its biological significance.

The influenza virus RNA polymerase as an innate immune agonist and antagonist

Influenza A viruses cause a mild-to-severe respiratory disease that affects millions of people each year. One of the many determinants of disease outcome is the innate immune response to the viral infection. While antiviral responses are essential for viral clearance, excessive innate immune activation promotes lung damage and disease. The influenza A virus RNA polymerase is one of viral proteins that affect innate immune activation during infection, but the mechanisms behind this activity are not well understood. In this review, we discuss how the viral RNA polymerase can both activate and suppress innate immune responses by either producing immunostimulatory RNA species or directly targeting the components of the innate immune signalling pathway, respectively. Furthermore, we provide a comprehensive overview of the polymerase residues, and their mutations, associated with changes in innate immune activation, and discuss their putative effects on polymerase function based on recent advances in our understanding of the influenza A virus RNA polymerase structure.