Yes / Living longer without simultaneously extending years spent in good health ("health span") is an increasing societal burden, demanding new therapeutic strategies. Hydrogen sulfide (H2S) can correct disease-related mitochondrial metabolic deficiencies, and supraphysiological H2S concentrations can pro health span. However, the efficacy and mechanisms of mitochondrion-targeted sulfide delivery molecules (mtH2S) administered across the adult life course are unknown. Using a Caenorhabditis elegans aging model, we compared untargeted H2S (NaGYY4137, 100 µM and 100 nM) and mtH2S (AP39, 100 nM) donor effects on life span, neuromuscular health span, and mitochondrial integrity. H2S donors were administered from birth or in young/middle-aged animals (day 0, 2, or 4 postadulthood). RNAi pharmacogenetic interventions and transcriptomics/network analysis explored molecular events governing mtH2S donor-mediated health span. Developmentally administered mtH2S (100 nM) improved life/health span vs. equivalent untargeted H2S doses. mtH2S preserved aging mitochondrial structure, content (citrate synthase activity) and neuromuscular strength. Knockdown of H2S metabolism enzymes and FoxO/daf-16 prevented the positive health span effects of mtH2S, whereas DCAF11/wdr-23 - Nrf2/skn-1 oxidative stress protection pathways were dispensable. Health span, but not life span, increased with all adult-onset mtH2S treatments. Adult mtH2S treatment also rejuvenated aging transcriptomes by minimizing expression declines of mitochondria and cytoskeletal components, and peroxisome metabolism hub components, under mechanistic control by the elt-6/elt-3 transcription factor circuit. H2S health span extension likely acts at the mitochondrial level, the mechanisms of which dissociate from life span across adult vs. developmental treatment timings. The small mtH2S doses required for health span extension, combined with efficacy in adult animals, suggest mtH2S is a potential healthy aging therapeutic. / A.R.V., M.W., and T.E. were supported by the US Army Research Office (W911NF-19-1-0235). L.S., M.W., and T.E. were supported by the United Mitochondrial Disease Foundation (PI-19-0985). L.S. was also supported by the University of Exeter Jubilee Scholarship. M.C., N.J.S., and T.E. were supported by the UK Space Agency (ST/R005737/1). N.J.S. and T.E. were supported by BBSRC (BB/N015894/1). S.A.V. was supported by NASA (NNX15AL16G). N.J.S. was supported by grants from NASA [NSSC22K0250; NSSC22K0278] and acknowledges the support of the Osteopathic Heritage Foundation through funding for the Osteopathic Heritage Foundation Ralph S. Licklider, D.O., Research Endowment in the Heritage College of Osteopathic Medicine.

Aging is the major risk factor for chronic age-related diseases characterized by loss of homeostasis, organ dysfunction, and inflammation. Calorie restriction (CR) has been shown to slow aging and delay the onset of chronic age-related diseases. Even though CR has many positive health effects, the degree and duration of the restriction needed would reduce the intervention's usefulness and make it challenging to start and maintain in humans. The difficulties brought on by CR have led to the development of CR mimetics that can mimic the effects of CR without reducing food intake (in an ad libitum state). We hypothesize that in PEPCK bovine Growth Hormone (bGH) overexpressing transgenic mice with accelerated metabolic and cognitive aging, the health span and phenotypes of aging can be improved by adding CR mimetics, a combination of lipoic acid, nicotinamide, thiamine, pyridoxine, and piperine to the diet. From 10 to 40 weeks of age, bGH-tg mice and their normal (N) littermates were fed CRM diet ad libitum. Normal littermates and bGH-tg mice fed a standard chow diet served as controls. Evaluation of the effects of CRM included insulin and glucose tolerance tests (ITT and GTT), indirect calorimetry as well as rotarod, working memory, grip strength testing. Body weight and percent fat mass were significantly lower, but percent lean mass was significantly higher in mice on a CRM diet at 40 weeks. At 19 weeks, insulin sensitivity was improved considerably in treated N and bGH-tg males. At 20 weeks of age, all mice on a CRM diet had significantly improved glucose tolerance and lower fasting glucose. At week 32, treated N female mice had significantly higher energy expenditure during the day and night per gram of body weight. In treated N males, this was true only during the day. Male bGH-tg mice on CRM diet had decreased energy expenditure during the night. Insulin sensitivity was significantly improved in treated male N and bGH-tg mice at week 37. Week 38 GTT showed enhanced glucose tolerance and lower fasting glucose in all mice on a CRM diet except Tg females. Week 39-40 Y-maze, rotarod and grip strength testing showed improved motor coordination and grip strength in all mice on CRM diet with no difference in working memory. Also, there was a significant improvement in metabolic and aging phenotype with lowered pro-inflammatory cytokines at the gene and protein levels in various tissues. Our study indicates the employed CRM produce the beneficial health effects in short-lived, insulin resistant bGH Tg mice but the effects are time-, sex-, genotype-, and diet-dependent. Most of the effects of this intervention resemble the effects of CR suggesting that employed compounds may act via similar mechanisms. This work was funded by the SIU-SOM Geriatrics Research Initiative (AB), NIA R01AG068288, and the Hillblom Foundation (PK).