Rational design of base, sugar and backbone modifications improves ADAR-mediated RNA editing.

AIMers are short, chemically modified oligonucleotides that induce A-to-I RNA editing through interaction with endogenous adenosine deaminases acting on RNA (ADAR) enzymes. Here, we describe the development of new AIMer designs with base, sugar and backbone modifications that improve RNA editing efficiency over our previous design. AIMers incorporating a novel pattern of backbone and 2' sugar modifications support enhanced editing efficiency across multiple sequences. Further efficiency gains were achieved through incorporation of an N-3-uridine (N3U), in place of cytidine (C), in the 'orphan base' position opposite the edit site. Molecular modeling suggests that N3U might enhance ADAR catalytic activity by stabilizing the AIMer-ADAR interaction and potentially reducing the energy required to flip the target base into the active site. Supporting this hypothesis, AIMers containing N3U consistently enhanced RNA editing over those containing C across multiple target sequences and multiple nearest neighbor sequence combinations. AIMers combining N3U and the novel pattern of 2' sugar chemistry and backbone modifications improved RNA editing both in vitro and in vivo. We provide detailed N3U synthesis methods and, for the first time, explore the impact of N3U and its analogs on ADAR-mediated RNA editing efficiency and targetable sequence space.

Carbon monoxide-induced autophagy enhances human mesenchymal stromal cell function via paracrine actions in murine polymicrobial sepsis.

Sepsis is a life-threatening process due to organ dysfunction resulting from severe infections. Mesenchymal stromal cells (MSCs) are being investigated as therapy for sepsis, along with conditioning regimens to improve their function. Carbon monoxide (CO) gas, which is cytoprotective at low doses, induces autophagy and is a mediator of inflammation. We evaluated CO-induced autophagy in human MSCs (hMSCs), and its impact on cell function in murine cecal ligation and puncture. Conditioning of hMSCs with CO ex vivo resulted in enhanced survival and bacterial clearance in vivo, and neutrophil phagocytosis of bacteria in vitro. Decreased neutrophil infiltration and less parenchymal cell death in organs were associated with increased macrophage efferocytosis of apoptotic neutrophils, promoting resolution of inflammation. These CO effects were lost when the cells were exposed to autophagy inhibition prior to gas exposure. When assessing paracrine actions of CO-induced autophagy, extracellular vesicles (EVs) were predominantly responsible. CO had no effect on EV production, but altered their miRNA cargo. Increased expression of miR-145-3p and miR-193a-3p by CO was blunted with disruption of autophagy, and inhibitors of these miRNAs led to a loss of neutrophil phagocytosis and macrophage efferocytosis. Collectively, CO-induced autophagy enhanced hMSC function during sepsis via paracrine actions of MSC-derived EVs.

Preclinical evaluation of stereopure antisense oligonucleotides for allele-selective lowering of mutant HTT.

Huntington's disease (HD) is an autosomal dominant disease caused by the expansion of cytosine-adenine-guanine (CAG) repeats in one copy of the HTT gene (mutant HTT, mHTT). The unaffected HTT gene encodes wild-type HTT (wtHTT) protein, which supports processes important for the health and function of the central nervous system. Selective lowering of mHTT for the treatment of HD may provide a benefit over nonselective HTT-lowering approaches, as it aims to preserve the beneficial activities of wtHTT. Targeting a heterozygous single-nucleotide polymorphism (SNP) where the targeted variant is on the mHTT gene is one strategy for achieving allele-selective activity. Herein, we investigated whether stereopure phosphorothioate (PS)- and phosphoryl guanidine (PN)-containing oligonucleotides can direct allele-selective mHTT lowering by targeting rs362273 (SNP3). We demonstrate that our SNP3-targeting molecules are potent, durable, and selective for mHTT in vitro and in vivo in mouse models. Through comparisons with a surrogate for the nonselective investigational compound tominersen, we also demonstrate that allele-selective molecules display equivalent potency toward mHTT with improved durability while sparing wtHTT. Our preclinical findings support the advancement of WVE-003, an investigational allele-selective compound currently in clinical testing (NCT05032196) for the treatment of patients with HD.

Lymphangioleiomyomatosis: circulating levels of FGF23 and pulmonary diffusion / Linfangioleiomiomatose: níveis circulantes de FGF23 e difusão pulmonar

ABSTRACT Objective: Lymphangioleiomyomatosis (LAM) is a rare, destructive disease of the lungs with a limited number of determinants of disease activity, which are a critical need for clinical trials. FGF23 has been implicated in several chronic pulmonary diseases. We aimed to determine the association between serum FGF23 levels and pulmonary function in a cohort of patients with LAM. Methods: This was a descriptive single-center study in which subjects with LAM and controls with unreported lung disease were recruited. Serum FGF23 levels were measured in all subjects. Clinical data, including pulmonary function testing, were retrospectively obtained from electronic medical records of LAM subjects. Associations between FGF23 levels and clinical features of LAM were explored via nonparametric hypothesis testing. Results: The sample comprised 37 subjects with LAM and 16 controls. FGF23 levels were higher in the LAM group than in the control group. In the LAM group, FGF23 levels above the optimal cutoff point distinguished 33% of the subjects who had nondiagnostic VEGF-D levels. Lower FGF23 levels were associated with impaired DLCO (p = 0.04), particularly for those with isolated diffusion impairment with no other spirometric abnormalities (p = 0.04). Conclusions: Our results suggest that FGF23 is associated with pulmonary diffusion abnormalities in LAM patients and elicit novel mechanisms of LAM pathogenesis. FGF23 alone or in combination with other molecules needs to be validated as a biomarker of LAM activity in future clinical research.

RESUMO Objetivo: A linfangioleiomiomatose (LAM) é uma doença rara e destrutiva dos pulmões com um número limitado de determinantes da atividade da doença, que são uma necessidade crítica para ensaios clínicos. O FGF23 já foi implicado em várias doenças pulmonares crônicas. O nosso objetivo foi determinar a associação entre os níveis séricos de FGF23 e a função pulmonar em uma coorte de pacientes com LAM. Métodos: Estudo descritivo unicêntrico no qual foram recrutados indivíduos com LAM e controles com doenças pulmonares não declaradas. Os níveis séricos de FGF23 foram medidos em todos os indivíduos. Os dados clínicos, incluindo testes de função pulmonar, foram obtidos retrospectivamente a partir dos prontuários eletrônicos dos indivíduos com LAM. As associações entre os níveis de FGF23 e as características clínicas da LAM foram exploradas por meio do teste de hipóteses não paramétrico. Resultados: A amostra incluiu 37 indivíduos com LAM e 16 controles. Os níveis de FGF23 foram mais altos no grupo LAM do que no grupo controle. No grupo LAM, níveis de FGF23 acima do ponto de corte ideal distinguiram 33% dos indivíduos com níveis não diagnósticos de VEGF-D. Níveis mais baixos de FGF23 estavam associados à DLCO comprometida (p = 0,04), particularmente naqueles com comprometimento isolado da difusão e sem outras alterações espirométricas (p = 0,04). Conclusões: Nossos resultados sugerem que o FGF23 está associado a alterações na difusão pulmonar em pacientes com LAM e potencialmente indicam novos mecanismos de patogênese da LAM. O FGF23 isoladamente ou em combinação com outras moléculas precisa ser validado como um biomarcador da atividade da LAM em futuras pesquisas clínicas.