F. Adiliaghdam1, A. Tsurumi1,2,3, Y. Dhole1, J. Ramirez1, F. Kuehn1, A. Munoz1, S. Hamarneh1, L. Rahme1,2,3, R. Hodin1 1Massachusetts General Hospital,General Surgery,Boston, MA, USA 2Shriners Hospitals For Children,Boston, MA, USA 3Harvard School Of Medicine,Department Of Microbiology And Immunobiology,Brookline, MA, USA
Introduction: Intestinal barrier dysfunction is considered to be an underlying factor in the pathophysiology of aging.We have previously shown that the gut enzyme intestinal alkaline phosphatase(IAP) maintains a healthy gut mucosal barrier.We therefore hypothesized that IAP could play an important role in aging process.
Methods: The wild-type(WT) Oregon-R Drosophilia Melanogaster was used to study the changes of gut alkaline phosphatase(AP)activity with aging and the effect of IAP supplementation on lifespan.Strain y/w67C23 was used to develop double-cross mutants for the midgut-specific AP genes in D.melanogaster, CG5150 and CG10827, for lifespan analysis. Furthermore,Gut barrier function was assessed using feeding with a blue food dye. Junction protein gene expression (DECad: Drosophila E-Cadherin and dlg1:discs large 1genes) assayed by qPCR from dissected mid-guts of 35 day-old WT and AP double-cross mutants. Three independent trials were done for all experiments.
Results: We found that AP activity in WT D.melanogaster’s midgut decreased with aging (P< 0.0001). In WT flies, oral IAP supplementation caused major lifespan extension compared to vehicle controls (median survival: 53d vs. 47d, P<0.0001). Climbing assay showed that IAP-treated flies climbed better than the vehicle-treated controls (%24 increase at week3, P< 0.0001 and 10% increase at week5, P<0.01). We also found that the double-cross mutants lacking the two AP genes died earlier than the WT-flies (median survival:42d vs. 47d, P<0.0001) and also performed worse in the climbing assay (21% decrease P<0.001). WT-flies showed a significant age-dependent breakdown in the gut barrier and this impairment was much worse in the AP double-cross mutants.(Figure1) Furthermore, AP double-cross mutants had significantly reduced mRNA levels of Junction proteins in the midgut compared to WT flies: DECad (Mutants vs. WT, 0.491± 0.070 Vs.1.0± 0.14 Relative Expression ,P=0.001) and dlg1 (Mutants vs. WT, 0.607± 0.07 Vs.1.0± 0.26 Relative Expression, P<0.01)
Conclusion: Decreasing endogenous levels of IAP is an important factor in age-dependent loss of intestinal integrity.We believe that IAP supplementation could represent a novel therapy to delay aging process.
