D609 protects retinal pigmented epithelium as a potential therapy for age-related macular degeneration

Accumulated oxidative damage may lead to irreversible retinal pigmented epithelium(RPE)cell death,which is considered to be the primary cause of dry age-related macular degeneration(AMD),leading to blindness in the elderly.However,an effective therapy for this disease is lacking.Here,we described a robust high-content screening procedure with a library of 814 protective compounds and found that D609 strongly protected RPE cells from sodium iodate(SI)-induced oxidative cell death and prolonged their healthy survival.D609 effectively attenuated excessive reactive oxygen species(ROS)and prevented severe mitochondrial loss due to oxidative stress in the RPE cells.Surprisingly,the potent antioxidative effects of D609 were not achieved through its own reducibility but were primarily dependent on its ability to increase the expression of metallothionein.The injection of this small water-soluble molecule also showed an explicit protective effect of the RPE layer in an SI-induced AMD mouse model.These findings suggested that D609 could serve as a novel antioxidative protector of RPE cells both in vitro and in vivo and unveiled a novel antioxidative mechanism of D609,which may ultimately have clinical applications for the treatment of AMD.

MomL inhibits bacterial antibiotic resistance through the starvation stringent response pathway

Antibiotic resistance in gram-negative pathogens has become one of the most serious global public health threats.The role of the N-acyl homoserine lactone(AHL)-mediated signaling pathway,which is widespread in gram-negative bacteria,in the bacterial resistance process should be studied in depth.Here,we report a degrading enzyme of AHLs,MomL,that inhibits the antibiotic resistance of Pseudomonas aeruginosa through a novel mechanism.The MomL-mediated reactivation of kanamycin is highly associated with the relA-mediated starvation stringent response.The degradation of AHLs by MomL results in the inability of LasR to activate relA,which,in turn,stops the activation of downstream rpoS.Further results show that rpoS directly regulates the type VI secretion system H2-T6SS.Under MomL treatment,inactivated RpoS fails to regulate H2-T6SS;therefore,the expression of effector phospholipase A is reduced,and the adaptability of bacteria to antibiotics is weakened.MomL in combination with kanamycin is effective against a wide range of gram-negative pathogenic bacteria.Therefore,this study reports a MomL-antibiotic treatment strategy on antibiotic-resistant bacteria and reveals its mechanism of action.