- Two recombinant human monoclonal antibodies that protect against lethal Andes hantavirus infection in vivo
- Hepatocyte Notch activation induces liver fibrosis in nonalcoholic steatohepatitis
- Lung-restricted inhibition of Janus kinase 1 is effective in rodent models of asthma
- IFN-γ–inducible antiviral responses require ULK1-mediated activation of MLK3 and ERK5
- The HDAC3–SMARCA4–miR-27a axis promotes expression of the PAX3:FOXO1 fusion oncogene in rhabdomyosarcoma
1. Two recombinant human monoclonal antibodies that protect against lethal Andes hantavirus infection in vivo
Andes hantavirus (ANDV) is an etiologic agent of hantavirus cardiopulmonary syndrome (HCPS), a severe disease characterized by fever, headache, and gastrointestinal symptoms that may progress to hypotension, pulmonary failure, and cardiac shock that results in a 25 to 40% case-fatality rate. Currently, there is no specific treatment or vaccine; however, several studies have shown that the generation of neutralizing antibody (Ab) responses strongly correlates with survival from HCPS in humans. In this study, Jose L. Garrido at Universidad de Concepción in Concepción, Chile and his colleagues screened 27 ANDV convalescent HCPS patient sera for their capacity to bind and neutralize ANDV in vitro. One patient who showed high neutralizing titer was selected to isolate ANDV–glycoprotein (GP) Abs. ANDV-GP–specific memory B cells were single cell sorted, and recombinant immunoglobulin G antibodies were cloned and produced. Two monoclonal Abs (mAbs), JL16 and MIB22, potently recognized ANDV-GPs and neutralized ANDV. They examined the post-exposure efficacy of these two mAbs as a monotherapy or in combination therapy in a Syrian hamster model of ANDV-induced HCPS, and both mAbs protected 100% of animals from a lethal challenge dose. These data suggest that monotherapy with mAb JL16 or MIB22, or a cocktail of both, could be an effective post-exposure treatment for patients infected with ANDV-induced HCPS.
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2. Hepatocyte Notch activation induces liver fibrosis in nonalcoholic steatohepatitis
Fibrosis is the major determinant of morbidity and mortality in patients with nonalcoholic steatohepatitis (NASH) but has no approved pharmacotherapy in part because of incomplete understanding of its pathogenic mechanisms. Here, Changyu Zhu at Columbia University in New York, USA and his colleagues report that hepatocyte Notch activity tracks with disease severity and treatment response in patients with NASH and is similarly increased in a mouse model of diet-induced NASH and liver fibrosis. Hepatocyte-specific Notch loss-of-function mouse models showed attenuated NASH-associated liver fibrosis, demonstrating causality to obesity-induced liver pathology. Conversely, forced activation of hepatocyte Notch induced fibrosis in both chow- and NASH diet–fed mice by increasing Sox9-dependent Osteopontin (Opn) expression and secretion from hepatocytes, which activate resident hepatic stellate cells. In a cross-sectional study, they found that OPN explains the positive correlation between liver Notch activity and fibrosis stage in patients. Further, they developed a Notch inhibitor [Nicastrin antisense oligonucleotide (Ncst ASO)] that reduced fibrosis in NASH diet–fed mice. In summary, these studies demonstrate the pathological role and therapeutic accessibility of the maladaptive hepatocyte Notch response in NASH-associated liver fibrosis.
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3. Lung-restricted inhibition of Janus kinase 1 is effective in rodent models of asthma
Preclinical and clinical evidence indicates that a subset of asthma is driven by type 2 cytokines such as interleukin-4 (IL-4), IL-5, IL-9, and IL-13. Additional evidence predicts pathogenic roles for IL-6 and type I and type II interferons. Because each of these cytokines depends on Janus kinase 1 (JAK1) for signal transduction, and because many of the asthma-related effects of these cytokines manifest in the lung, Hart S. Dengler at Genentech in South San Francisco, USA and his colleagues hypothesized that lung-restricted JAK1 inhibition may confer therapeutic benefit. To test this idea, they synthesized iJak-381, an inhalable small molecule specifically designed for local JAK1 inhibition in the lung. In pharmacodynamic models, iJak-381 suppressed signal transducer and activator of transcription 6 activation by IL-13. Furthermore, iJak-381 suppressed ovalbumin-induced lung inflammation in both murine and guinea pig asthma models and improved allergen-induced airway hyperresponsiveness in mice. In a model driven by human allergens, iJak-381 had a more potent suppressive effect on neutrophil-driven inflammation compared to systemic corticosteroid administration. The inhibitor iJak-381 reduced lung pathology, without affecting systemic Jak1 activity in rodents. Their data show that local inhibition of Jak1 in the lung can suppress lung inflammation without systemic Jak inhibition in rodents, suggesting that this strategy might be effective for treating asthma.
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4. IFN-γ–inducible antiviral responses require ULK1-mediated activation of MLK3 and ERK5
It is well established that activation of the transcription factor signal transducer and activator of transcription 1 (STAT1) is required for the interferon-γ (IFN-γ)–mediated antiviral response. Here, Diana Saleiro at Northwestern University in Chicago, USA and her colleagues found that IFN-γ receptor stimulation also activated Unc-51–like kinase 1 (ULK1), an initiator of Beclin-1–mediated autophagy. Furthermore, the interaction between ULK1 and the mitogen-activated protein kinase kinase kinase MLK3 (mixed lineage kinase 3) was necessary for MLK3 phosphorylation and downstream activation of the kinase ERK5. This autophagy-independent activity of ULK1 promoted the transcription of key antiviral IFN-stimulated genes (ISGs) and was essential for IFN-γ–dependent antiviral effects. These findings define a previously unknown IFN-γ pathway that appears to be a key element of the antiviral response.
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5. The HDAC3–SMARCA4–miR-27a axis promotes expression of the PAX3:FOXO1 fusion oncogene in rhabdomyosarcoma
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood with an unmet clinical need for decades. A single oncogenic fusion gene is associated with treatment resistance and a 40 to 45% decrease in overall survival. Narendra Bharathy at Children’s Cancer Therapy Development Institute in Beaverton, USA and his colleagues previously showed that expression of this PAX3:FOXO1 fusion oncogene in alveolar RMS (aRMS) mediates tolerance to chemotherapy and radiotherapy and that the class I–specific histone deacetylase (HDAC) inhibitor entinostat reduces PAX3:FOXO1 protein abundance. Here, they established the antitumor efficacy of entinostat with chemotherapy in various preclinical cell and mouse models and found that HDAC3 inhibition was the primary mechanism of entinostat-induced suppression of PAX3:FOXO1 abundance. HDAC3 inhibition by entinostat decreased the activity of the chromatin remodeling enzyme SMARCA4, which, in turn, derepressed the microRNA miR-27a. This reexpression of miR-27a led to PAX3:FOXO1 mRNA destabilization and chemotherapy sensitization in aRMS cells in culture and in vivo. Furthermore, a phase 1 clinical trial (ADVL1513) has shown that entinostat is tolerable in children with relapsed or refractory solid tumors and is planned for phase 1B cohort expansion or phase 2 clinical trials. Together, these results implicate an HDAC3–SMARCA4–miR-27a–PAX3:FOXO1 circuit as a driver of chemoresistant aRMS and suggest that targeting this pathway with entinostat may be therapeutically effective in patients.
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