Aminoacyl-tRNA synthetase inhibition activates a pathway that branches from the canonical amino acid response in mammalian cells.

Signaling pathways that sense amino acid abundance are integral to tissue homeostasis and cellular defense. Our laboratory has previously shown that halofuginone (HF) inhibits the prolyl-tRNA synthetase catalytic activity of glutamyl-prolyl-tRNA synthetase (EPRS), thereby activating the amino acid response (AAR). We now show that HF treatment selectively inhibits inflammatory responses in diverse cell types and that these therapeutic benefits occur in cells that lack GCN2, the signature effector of the AAR. Depletion of arginine, histidine, or lysine from cultured fibroblast-like synoviocytes recapitulates key aspects of HF treatment, without utilizing GCN2 or mammalian target of rapamycin complex 1 pathway signaling. Like HF, the threonyl-tRNA synthetase inhibitor borrelidin suppresses the induction of tissue remodeling and inflammatory mediators in cytokine-stimulated fibroblast-like synoviocytes without GCN2, but both aminoacyl-tRNA synthetase (aaRS) inhibitors are sensitive to the removal of GCN1. GCN1, an upstream component of the AAR pathway, binds to ribosomes and is required for GCN2 activation. These observations indicate that aaRS inhibitors, like HF, can modulate inflammatory response without the AAR/GCN2 signaling cassette, and that GCN1 has a role that is distinct from its activation of GCN2. We propose that GCN1 participates in a previously unrecognized amino acid sensor pathway that branches from the canonical AAR.

Acute respiratory distress syndrome.

ABSTRACT: Acute respiratory distress syndrome (ARDS) is a severe, often fatal, lung condition frequently seen in patients in the ICU. ARDS is triggered by an inciting event such as pneumonia or sepsis, which is followed by an inappropriate host inflammatory response that results in pulmonary edema and impaired gas exchange, and may progress to fibrosis. With the increased spotlight and discussion focused on ARDS during the COVID-19 pandemic, healthcare providers must be able to identify and manage symptoms based on evidence-based research.

Engineering of a hybrid nanoparticle-based nicotine nanovaccine as a next-generation immunotherapeutic strategy against nicotine addiction: A focus on hapten density.

Although vaccination is a promising way to combat nicotine addiction, most traditional hapten-protein conjugate nicotine vaccines only show limited efficacy due to their poor recognition and uptake by immune cells. This study aimed to develop a hybrid nanoparticle-based nicotine vaccine with improved efficacy. The focus was to study the impact of hapten density on the immunological efficacy of the proposed hybrid nanovaccine. It was shown that the nanovaccine nanoparticles were taken up by the dendritic cells more efficiently than the conjugate vaccine, regardless of the hapten density on the nanoparticles. At a similar hapten density, the nanovaccine induced a significantly stronger immune response against nicotine than the conjugate vaccine in mice. Moreover, the high- and medium-density nanovaccines resulted in significantly higher anti-nicotine antibody titers than their low-density counterpart. Specifically, the high-density nanovaccine exhibited better immunogenic efficacy, resulting in higher anti-nicotine antibody titers and lower anti-carrier protein antibody titers than the medium- and low-density versions. The high-density nanovaccine also had the best ability to retain nicotine in serum and to block nicotine from entering the brain. These results suggest that the hybrid nanoparticle-based nicotine vaccine can elicit strong immunogenicity by modulating the hapten density, thereby providing a promising next-generation immunotherapeutic strategy against nicotine addiction.