Legend: Swiss 3T3 fibroblasts were plated on glass coverslips, grown to 30% confluency in DMEM plus 10% FBS and serum starved for  24 h in media containing 1% FBS followed by 24 h in serum free media.  Cells were treated with a buffer control (A) or 1 µg/ml CN03 for 2 h at 37°C/5% CO2 (B).  Cells were then fixed, stained with Acti-stainTM 488 phalloidin (Cat.# PHDG1), and visualized by fluorescence microscopy.  Images were taken at a magnification of 40x.  The control cells (A) exhibited very few stress fibers, whereas treatment with CN03 (B) resulted in the development of abundant stress fibers. Under similar conditions, RhoA was activated ~10-fold as determined using the RhoA G-LISA® activation assay (Cat.# BK124) (See Fig. 2).

Legend: Swiss 3T3 fibroblasts were plated on glass coverslips, grown to 30% confluency in DMEM plus 10% FBS and serum starved for  24 h in media containing 1% FBS followed by 24 h in serum free media.  Cells were treated with a buffer control (A) or 1 µg/ml CN03 for 2 h at 37°C/5% CO2 (B).  Cells were then fixed, stained with Acti-stainTM 488 phalloidin (Cat.# PHDG1), and visualized by fluorescence microscopy.  Images were taken at a magnification of 40x.  The control cells (A) exhibited very few stress fibers, whereas treatment with CN03 (B) resulted in the development of abundant stress fibers. Under similar conditions, RhoA was activated ~10-fold as determined using the RhoA G-LISA® activation assay (Cat.# BK124) 

Sepsis and the accompanying systemic inflammatory response are an over-reaction of an organism’s immune system in response to infection or injury which results in organ dysfunction/failure if untreated. A healthy intestinal barrier is a primary defense against these pathogenic processes. Here, the authors investigate how NLRP3 inflammasome and RhoA participate in sepsis-induced intestinal barrier dysfunction and their functional status after treatment with astragaloside IV (AS-IV), a bioactive compound from Astragalus membranaceus. In in vivo (cecal ligation and puncture mice) and in vitro (Caco-2 cells treated with lipopolysaccharide [LPS]) models of sepsis, AS-IV alleviated barrier dysfunction (e.g., decreased mouse mortality, cytokine release, and barrier permeability and increased tight junction expression in vivo; reduced cytokine levels, improved gut barrier function absent cytotoxicity in vitro). NLRP3 inflammasome and RhoA activities were elevated in intestinal tissues and Caco-2 cells and correspondingly reduced after AS-IV administration. Furthermore, a cell-permeable Rho activator prevented the effects of AS-IV, while a cell-permeable Rho inhibitor antagonized LPS-induced NLRP3 inflammasome activation. Cytoskeleton’s RhoA G-LISA activation assay kit, cell-permeable Rho activator, and Rho inhibitor (Cat. # BK124, CN03, CT04, respectively) were essential in identifying RhoA (and NLRP3 inflammasome) as the molecular targets of AS-IV in the alleviation of sepsis-induced barrier dysfunction.  

  

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Ryan Kogstad