ABSTRACT Barriers of the central nervous system (CNS), such as the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB), regulate the two-way exchange of material between the blood and CNS. These barriers pose a considerable challenge for efficacious delivery of intravenously administered therapies into the CNS, motivating exploration of their function and ways to modulate their properties. While the BBB and BCSFB can become dysfunctional in patients with chronic CNS diseases, few studies have focused on strategies for targeting these interfaces. Here, we showed that an intravenously administered albumin-binding lipid-siRNA conjugate was delivered to and silences genes within brain endothelial cells and choroid plexus epithelial cells, which comprise the BBB and BCSFB, respectively. A single intravenous dose of lipid-siRNA conjugate was delivered to ∼100% of brain endothelial cells and major choroid plexus cell types, without any substantial delivery into brain parenchymal tissue. Sustained gene silencing was achieved in both brain endothelial cells (over two weeks) and bulk choroid plexus tissues (up to one month). Moreover, single cell RNA sequencing demonstrated gene knockdown in capillaries, venous endothelial cells, and choroid plexus epithelial cells without silencing genes in parenchymal cell populations. Collectively, this work establishes an effective nonviral framework to mediate gene inhibition in the brain barriers. GRAPHICAL ABSTRACT

We are naturally chimeras. Apart from our own cells originating from the fertilized egg, placental mammals receive small numbers of maternal cells called maternal microchimerism (MMc) that persist throughout one's whole life. Not only are varying frequencies of MMc cells reported in seemingly contradicting phenomena, including immune tolerance and possible contribution to autoimmune-like disease, but frequencies are observable even among healthy littermates showing varying MMc frequencies and cell type repertoire. These varying differences in MMc frequencies or cell types could be contributing to the diverse phenomena related to MMc. However, factors biasing these MMc differences remain largely unknown. Here, we tested whether immunological activation leads to differing MMc frequencies, based on our recent study that suggests that most maternal cells are immune-related. Unexpectedly, fluorescence-activated cell sorting analysis on the murine spleen, thymus, and liver following maternal immune activation by mid-gestational lipopolysaccharide intraperitoneal injections detected no significant difference in the number, or ratio of, immune-related maternal cells in the tested embryonic organs of healthy offspring. These findings suggest that MMc frequencies remain stable even under immune-activated conditions, implying a possible control system of MMc migration against changes in the immunological conditions.
© 2024. Published by The Company of Biologists.

Short-interfering RNA (siRNA) has gained significant interest for treatment of neurological diseases by providing the capacity to achieve sustained inhibition of nearly any gene target. Yet, achieving efficacious drug delivery throughout deep brain structures of the CNS remains a considerable hurdle. We herein describe a lipid-siRNA conjugate that, following delivery into the cerebrospinal fluid (CSF), is transported effectively through perivascular spaces, enabling broad dispersion within CSF compartments and through the CNS parenchyma. We provide a detailed examination of the temporal kinetics of gene silencing, highlighting potent knockdown for up to five months from a single injection without detectable toxicity. Single-cell RNA sequencing further demonstrates gene silencing activity across diverse cell populations in the parenchyma and at brain borders, which may provide new avenues for neurological disease-modifying therapies.

The selection process for advanced therapies in patients with inflammatory bowel diseases (IBDs) must prioritize safety, especially when considering new biologic agents or oral molecule modulators. In C57BL/6 mice, oral infection with Toxoplasma gondii induces intestinal inflammation through excessive tumor necrosis factor (TNF) production, making TNF neutralization a potential therapeutic intervention. Considering this, the present study aimed to evaluate the therapeutic effects of BmooMP-α-I, a snake venom metalloprotease isolated from Bothrops moojeni, which could promote TNF hydrolysis, in treating T. gondii-induced ileitis. The results showed that C57BL/6 mice orally infected with 50 cysts of T. gondii from the Me49 strain and treated with BmooMP-α-I exhibited prolonged survival and improved morbidity scores. Additionally, the treatment ameliorated both the macroscopic and microscopic aspects of the intestine, reduced macrophage influx, and decreased the production of inflammatory mediators by mesenteric lymph node cells. These findings provide compelling experimental evidence supporting the ability of BmooMP-α-I to alleviate ileal inflammation. Considering that the currently available therapeutic protocols are not completely effective and often result in side effects, the exploration of alternative strategies involving novel therapeutic agents, as demonstrated in this study, has the potential to significantly enhance the quality of life for patients suffering from inflammatory bowel diseases.
© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

The capacity to survive and thrive in conditions of limited resources and high inflammation is a major driver of tumor malignancy. Here we identified slow-cycling ADAM12+PDGFRα+ mesenchymal stromal cells (MSCs) induced at the tumor margins in mouse models of melanoma, pancreatic cancer and prostate cancer. Using inducible lineage tracing and transcriptomics, we demonstrated that metabolically altered ADAM12+ MSCs induced pathological angiogenesis and immunosuppression by promoting macrophage efferocytosis and polarization through overexpression of genes such as Gas6, Lgals3 and Csf1. Genetic depletion of ADAM12+ cells restored a functional tumor vasculature, reduced hypoxia and acidosis and normalized CAFs, inducing infiltration of effector T cells and growth inhibition of melanomas and pancreatic neuroendocrine cancer, in a process dependent on TGF-β. In human cancer, ADAM12 stratifies patients with high levels of hypoxia and innate resistance mechanisms, as well as factors associated with a poor prognosis and drug resistance such as AXL. Altogether, our data show that depletion of tumor-induced slow-cycling PDGFRα+ MSCs through ADAM12 restores antitumor immunity.
© 2023. The Author(s).