Summary Pathogens commonly disrupt host cell processes or cause damage, but the surveillance mechanisms used by animals to monitor these attacks are poorly understood. Upon infection with pathogenic Pseudomonas aeruginosa, the nematode C. elegans upregulates infection response gene irg-1 using the zip-2 bZIP transcription factor. Here we show that P. aeruginosa infection inhibits mRNA translation in the intestine via the endocytosed translation inhibitor Exotoxin A, which leads to an increase in ZIP-2 protein levels. In the absence of infection we find that the zip-2/irg-1 pathway is upregulated following disruption of several core host processes, including inhibition of mRNA translation. ZIP-2 induction is conferred by a conserved upstream open reading frame in zip-2 that could de-repress ZIP-2 translation upon infection. Thus, translational inhibition, a common pathogenic strategy, can trigger activation of an immune surveillance pathway to provide host defense.

Gypenosides (GP), the saponin extract derived from the Gynostemma pentaphyllum Makino, a widely reputed medicinal plant in China, has been reported to have some neuroprotective effects. We used a rat model of chronic cerebral hypoperfusion to investigate the protective effects of GP on the cortex and hippocampal CA1 region and the underlying mechanisms for its inhibition of cognitive decline. Daily doses of 100 and 200 mg/kg GP were orally administered to adult male Sprague-Dawley rats for 61 days after inducing cerebral hypoperfusion experimentally, and spatial learning and memory were assessed using the Morris water maze. Antioxidative capability was measured biochemically. The levels of lipid peroxidation and oxidative DNA damage were assessed by immunohistochemical staining for 4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine, respectively. Activated astrocytes were assessed by immunohistochemical staining and western blotting with GFAP antibodies. Rats receiving 200 mg/kg GP had better spatial learning and memory than saline-treated rats. GP 200 mg/kg/day were found to markedly enhance antioxidant abilities, decrease lipid peroxide products and oxidative DNA damage, and reduce the activation of inflammatory astrocytes. However, GP 100 mg/kg had no significant effects. GP may have therapeutic potential for the treatment of dementia induced by chronic cerebral hypoperfusion and further evaluation is warranted.

Spinal cord injury (SCI) remains a major challenge for regenerative medicine. Following SCI, axon growth inhibitors and other inflammatory responses prevent functional recovery. Previous studies have demonstrated that rolipram, an anti-inflammatory and cyclic adenosine monophosphate preserving small molecule, improves spinal cord regeneration when delivered systemically. However, more recent studies showed that rolipram has some adverse effects in spinal cord repair. Here, we developed a drug-delivery platform for the local delivery of rolipram into the spinal cord. The potential of drug-eluting microfibrous patches for continuous delivery of high and low-dose rolipram concentrations was characterized in vitro. Following C5 hemisections, athymic rats were treated with patches loaded with low and high doses of rolipram. In general, animals treated with low-dose rolipram experienced greater functional and anatomical recovery relative to all other groups. Outcomes from the high-dose rolipram treatment were similar to those with no treatment. In addition, high-dose treated animals experienced reduced survival rates suggesting that systemic toxicity was reached. With the ability to control the release of drug dosage locally within the spinal cord, drug-eluting microfibrous patches demonstrate the importance of appropriate local release-kinetics of rolipram, proving their usefulness as a therapeutic platform for the study and repair of SCI.

Vascular endothelial cells (ECs) are constantly exposed to blood flow-induced shear stress; these forces strongly influence the behaviors of neighboring vascular smooth muscle cells (VSMCs). VSMC migration is a key event in vascular wall remodeling. In this study, the authors assessed the difference between VSMC migration in VSMC/EC coculture under static and shear stress conditions. Utilizing a parallel-plate coculture flow chamber system and Transwell migration assays, they demonstrated that human ECs cocultured with VSMCs under static conditions induced VSMC migration, whereas laminar shear stress (1.5 Pa, 15 dynes/cm2) applied to the EC side for 12 h significantly inhibited this process. The changes in VSMC migration is mainly dependent on the close interactions between ECs and VSMCs. Western blotting showed that there was a consistent correlation between the level of Akt phosphorylation and the efficacy of shear stress-mediated EC regulation of VSMC migration. Wortmannin and Akti significantly inhibited the EC-induced effect on VSMC Akt phosphorylation and migration. These results indicate that shear stress protects against endothelial regulation of VSMC migration, which may be an atheroprotective function on the vessel wall.

Background/Aims: Physiological mechanical stretch in vivo helps to maintain the quiescent contractile differentiation of vascular smooth muscle cells (VSMCs), but the underlying mechanisms are still unclear. Here, we investigated the effects of SIRT1 in VSMC differentiation in response to mechanical cyclic stretch. Methods and Results: Rat VSMCs were subjected to 10%-1.25Hz-cyclic stretch in vitro using a FX-4000T system. The data indicated that the expression of contractile markers, including α-actin, calponin and SM22α, was significantly enhanced in VSMCs that were subjected to cyclic stretch compared to the static controls. The expression of SIRT1 and FOXO3a was increased by the stretch, but the expression of FOXO4 was decreased. Decreasing SIRT1 by siRNA transfection attenuated the stretch-induced expression of contractile VSMC markers and FOXO3a. Furthermore, increasing SIRT1 by either treatment with activator resveratrol or transfection with a plasmid to induce overexpression increased the expression of FOXO3a and contractile markers, and decreased the expression of FOXO4 in VSMCs. Similar trends were observed in VSMCs of SIRT1 (+/-) knockout mice. The overexpression of FOXO3a promoted the expression of contractile markers in VSMCs, while the overexpression of FOXO4 demonstrated the opposite effect. Conclusion: Our results indicated that physiological cyclic stretch promotes the contractile differentiation of VSMCs via the SIRT1/FOXO pathways and thus contributes to maintaining vascular homeostasis.