Pharmacological strategies that boost intracellular NAD + are highly coveted for their therapeutic potential. One approach is activation of nicotinamide phosphoribosyltransferase (NAMPT) to increase production of nicotinamide mononucleotide (NMN), the predominant NAD + precursor in mammalian cells. A high-throughput screen for NAMPT activators and hit-to-lead campaign yielded SBI-797812, a compound that is structurally similar to active-site directed NAMPT inhibitors and blocks binding of these inhibitors to NAMPT. SBI-797812 shifts the NAMPT reaction equilibrium towards NMN formation, increases NAMPT affinity for ATP, stabilizes phosphorylated NAMPT at His247, promotes consumption of the pyrophosphate by-product, and blunts feedback inhibition by NAD + . These effects of SBI-797812 turn NAMPT into a “super catalyst” that more efficiently generates NMN. Treatment of cultured cells with SBI-797812 increases intracellular NMN and NAD + . Dosing of mice with SBI-797812 elevates liver NAD + . Small molecule NAMPT activators such as SBI-797812 are a pioneering approach to raise intracellular NAD + and realize its associated salutary effects.

Background Profiling of plasma metabolites to predict the course of heart failure (HF) appears promising but validation and incremental value are less established. Methods Patients meeting Framingham HF criteria with history of reduced ejection fraction were (n=1032) were randomly divided into derivation and validation cohorts (n=516 each). Amino acids, organic acids, and acylcarnitines were quantified using mass spectrometry in fasting plasma samples. We derived a prognostic metabolite profile (PMP) in the derivation cohort using Lasso-penalized Cox regression. Validity was assessed by 10-fold cross-validation in the derivation cohort, and by standard testing in the validation cohort. The PMP was analyzed as both a continuous variable (PMPscore) and dichotomized at the median (PMPcat), in univariate and multivariate models adjusted for clinical risk score and NTproBNP. Results Overall 48% of patients were African American, 35% were female, and average age was 69 years. After median follow-up of 34 months, there were 256 deaths (127 and 129 in derivation and validation cohorts, respectively). Optimized modeling defined the 13 metabolite PMP, which cross-validated as both PMPscore (hazard ratio [HR] 3.27, p<2×10−16) and PMPcat (HR=3.04, p=2.93×10−8). The validation cohort showed similar results; PMPscore HR=3.9 (p<2×10−16) and PMPcat HR=3.99 (p=3.47×10−9). In adjusted models PMP remained associated with mortality in the cross-validated derivation cohort (PMPscore HR=1.63, p=0.0029; PMPcat HR=1.47, p=0.081) and validation cohort (PMPscore HR=1.54, p=0.037; PMPcat HR=1.69, p=0.043). Conclusion Plasma metabolite profile varies across HF subgroups and is associated with survival incremental to conventional predictors. Additional investigation is warranted to define mechanisms and clinical applications.

Summary Nitric oxide (NO) is generated from arginine and oxygen via NO synthase (NOS). Staphylococcus aureus NOS (saNOS) has previously been shown to affect virulence and resistance to exogenous oxidative stress, yet the exact mechanism is unknown. Herein, we report a previously-undescribed role of saNOS in S. aureus aerobic physiology. Specifically, aerobic S. aureus nos mutant cultures presented with elevated endogenous reactive oxygen species (ROS) and superoxide levels, as well as increased membrane potential, increased respiratory dehydrogenase activity, and slightly elevated oxygen consumption. Elevated ROS levels in the nos mutant likely resulted from altered respiratory function, as inhibition of NADH dehydrogenase brought ROS levels back to wild-type levels. These results indicate that, in addition to its recently-reported role in regulating the switch to nitrate-based respiration during low-oxygen growth, saNOS also plays a modulatory role during aerobic respiration. Multiple transcriptional changes were also observed in the nos mutant, including elevated expression of genes associated with oxidative/nitrosative stress, anaerobic respiration, and lactate metabolism. Targeted metabolomics revealed decreased cellular lactate levels, and altered levels of TCA cycle intermediates, the latter of which may be related to decreased aconitase activity. Collectively, these findings demonstrate a key contribution of saNOS to S. aureus aerobic respiratory metabolism.