GATA1 deletion in human pluripotent stem cells increases differentiation yield and maturity of neutrophils.

Human pluripotent stem cell (hPSC)-derived tissues can be used to model diseases in cell types that are challenging to harvest and study at-scale, such as neutrophils. Neutrophil dysregulation, specifically neutrophil extracellular trap (NET) formation, plays a critical role in the prognosis and progression of multiple diseases, including COVID-19. While hPSCs can generate limitless neutrophils (iNeutrophils) to study these processes, current differentiation protocols generate heterogeneous cultures of granulocytes and precursors. Here, we describe a method to improve iNeutrophil differentiations through the deletion of GATA1. GATA1 knockout (KO) iNeutrophils are nearly identical to primary neutrophils in form and function. Unlike wild-type iNeutrophils, GATA1 KO iNeutrophils generate NETs in response to the physiologic stimulant lipopolysaccharide, suggesting they are a more accurate model when performing NET inhibitor screens. Furthermore, through deletion of CYBB, we demonstrate that GATA1 KO iNeutrophils are a powerful tool in determining involvement of a given protein in NET formation.

FGF21 Normalizes Plasma Glucose in Mouse Models of Type 1 Diabetes and Insulin Receptor Dysfunction.

Fibroblast growth factor (FGF) 21 is a member of the FGF family of proteins. The biological activity of FGF21 was first shown to induce insulin-independent glucose uptake in adipocytes through the GLUT1 transporter. Subsequently, it was shown to have effects on the liver to increase fatty acid oxidation. FGF21 treatment provides beneficial metabolic effects in both animal models and patients with obesity, type 2 diabetes mellitus (T2D) and/or fatty liver disease. In this paper, we revisited the original finding and found that insulin-independent glucose uptake in adipocytes is preserved in the presence of an insulin receptor antagonist. Using a 40-kDa PEGylated (PEG) and half-life extended form of FGF21 (FGF21-PEG), we extended these in vitro results to 2 different mouse models of diabetes. FGF21-PEG normalized plasma glucose in streptozotocin-treated mice, a model of type 1 diabetes (T1D), without restoring pancreatic ß-cell function. FGF21-PEG also normalized plasma glucose levels and improved glucose tolerance in mice chronically treated with an insulin competitive insulin receptor antagonist, a model of autoimmune/type-B insulin resistance. These data extend the pharmacological potential of FGF21 beyond the settings of T2D, fatty liver, and obesity.

Increased type 2 inflammation post rhinovirus infection in patients with moderate asthma.

Rhinovirus (RV) infections are a major cause of exacerbations in patients with asthma. Experimental RV challenges can provide insight into the pathophysiology of viral exacerbations. Previous reports, investigating mild or moderate asthma patients, have shown an upregulation in type 2 inflammation post RV infection, however, studies specifically involving asthma patients taking inhaled corticosteroids have concentrated on symptoms and lung function, rather than the inflammatory response. Eleven moderate asthma patients were inoculated with RV. Cold symptoms and asthma control were assessed at baseline and post infection. Nasal epithelial lining fluid and bronchial alveolar lavage (BAL) fluid were collected at baseline and 4 days post infection for assessment of inflammatory proteins. Patients suffered increased cold symptoms and decreased asthma control within 7 days of infection. Antiviral mechanisms were induced following inoculation, with increases in interferon -α, ß, γ and λ, as well as CXCL10 and CXCL11. Type 2 inflammatory cytokines were also significantly elevated post RV infection in both nasal and bronchial samples. In BAL, epithelial derived IL-25 and IL-33 levels strongly correlated with Th2 cytokines, IL-4, IL-5 and IL-13. We show how experimental rhinovirus challenge regulates lung and nasal biomarkers in asthma patients taking inhaled corticosteroids. These biomarkers could be used to evaluate the effects of novel drugs for asthma.

Small-molecule WNK inhibition regulates cardiovascular and renal function.

The With-No-Lysine (K) (WNK) kinases play a critical role in blood pressure regulation and body fluid and electrolyte homeostasis. Herein, we introduce the first orally bioavailable pan-WNK-kinase inhibitor, WNK463, that exploits unique structural features of the WNK kinases for both affinity and kinase selectivity. In rodent models of hypertension, WNK463 affects blood pressure and body fluid and electro-lyte homeostasis, consistent with WNK-kinase-associated physiology and pathophysiology.