Oral Delivery of the Appetite Suppressing Neuropeptide PYY(3-36) through the Vitamin B12 Dietary Uptake Pathway

Injections of hPYY(3-36) have shown positive effects on appetite regulation. With nearly 400 million adults worldwide considered obese, these positive effects have sparked an increased interest in hPYY(3-36) research, including release profiles, receptor targets, and medicinal applications. A major area of interest is oral delivery of hPYY(3-36) that can display clinically relevant weight-loss outcomes in what would be a highly patient compliant route. The vitamin B12 (B12) pathway has already been successfully used for oral delivery of other peptides including erythropoietin and insulin, but the quantity delivered has been below clinically relevant levels. Herein, we present synthesis, purification, characterization, and clinically relevant in vivo oral delivery of B12-hPYY(3-36) conjugates. The hPYY(3-36) sequence was modified at the N terminus with an octahistidine tag and factor Xa protease sequence along with the small ubiquitin-like modifier (SUMO) tag and expressed in Escherichia coli. The fusion protein was purified with a yield of 30 ± 7 mg/L. The SUMO-tagged hPYY(3-36) was digested with two different proteases to return either His-tagged hPYY(3-36) or unmodified hPYY(3-36) that were subsequently purified and characterized

Non-Monotonic Survival of Staphylococcus aureus with Respect to Ciprofloxacin Concentration Arises from Prophage-Dependent Killing of Persisters

Staphylococcus aureus is a notorious pathogen with a propensity to cause chronic, non-healing wounds. Bacterial persisters have been implicated in the recalcitrance of S. aureus infections, and this motivated us to examine the persistence of S. aureus to ciprofloxacin, a quinolone antibiotic. Upon treatment of exponential phase S. aureus with ciprofloxacin, we observed that survival was a non-monotonic function of ciprofloxacin concentration. Maximal killing occurred at 1 µg/mL ciprofloxacin, which corresponded to survival that was up to ~40-fold lower than that obtained with concentrations ≥ 5 µg/mL. Investigation of this phenomenon revealed that the non-monotonic response was associated with prophage induction, which facilitated killing of S. aureus persisters. Elimination of prophage induction with tetracycline was found to prevent cell lysis and persister killing. We anticipate that these findings may be useful for the design of quinolone treatments

Tea Tree Essential Oil Kills <i>Escherichia coli</i> and <i>Staphylococcus epidermidis</i> Persisters

Persister cells are a small subpopulation of non-growing bacteria within a population that can survive long exposures to antibiotic treatment. Following antibiotic removal, persister cells can regrow and populate, playing a key role in the chronic reoccurrence of bacterial infections. The development of new molecules and methods to kill bacterial persisters is critical. Essential oils and other natural products have long been studied for their antimicrobial effects. Here, we studied the effectiveness of tea tree essential oil (TTO), a common component in many commercial care products, against Escherichia coli and Staphylococcus epidermidis persister cells. Using biphasic kill curve assays, we found that concentrations of 0.5% and 1.0% TTO for E. coli and S. epidermidis, respectively, completely eradicated persister cells over a period of 24 h, with the component terpinen-4-ol responsible for most of the killing. Using a colorimetric assay, it was determined that the TTO exhibited its anti-persister effects through a membrane disruption mechanism

The role of metabolism in bacterial persistence

Bacterial persisters are phenotypic variants with extraordinary tolerances toward antibiotics. Persister survival has been attributed to inhibition of essential cell functions during antibiotic stress, followed by reversal of the process and resumption of growth upon removal of the antibiotic. Metabolism plays a critical role in this process, since it participates in the entry, maintenance, and exit from the persister phenotype. Here, we review the experimental evidence that demonstrates the importance of metabolism to persistence, highlight the successes and potential for targeting metabolism in the search for anti-persister therapies, and discuss the current methods and challenges to understand persister physiology