Same molecule but different expression: aging and sepsis trigger NLRP3 inflammasome activation,a target of melatonin

The connection between the innate immune system, clock genes, and mitochondrial bioenergetics was analyzed during aging and sepsis in mouse heart. Our results suggest that the sole NF‐κB activation does not explain the inflammatory process underlying aging; the former also triggers the NLRP3 inflammasome that enhances caspase‐1‐dependent maturation of IL‐1β. In this way, aged mice enter into a vicious cycle as IL‐1β further activates the NF‐κB/NLRP3 inflammasome link. The origin of NF‐κB activation was related to the age‐dependent Bmal1/Clock/RORα/Rev‐Erbα loop disruption, which lowers NAD⁺ levels, reducing the SIRT1 deacetylase ability to inactivate NF‐κB. Consequently, NF‐κB binding to DNA increases, raising the formation of proinflammatory mediators and inducing mitochondrial impairment. The cycle is then closed with the subsequent NLRP3 inflammasome activation. This paired contribution of the innate immune pathways serves as a catalyst to magnify the response to sepsis in aged compared with young mice. Melatonin administration blunted the septic response, reducing inflammation and oxidative stress, and enhancing mitochondrial function at the levels of nonseptic aged mice, but it did not counteract the age‐related inflammation. Together, our results suggest that, although with different strengths, chronoinflammaging constitutes the biochemical substrate of aging and sepsis, and identifies the NLRP3 inflammasome as a new molecular target for melatonin, providing a rationale for its use in NLRP3‐dependent diseases.     

Influence of Oxynitrided Surface in the Production of a Less Susceptible Titanium Surface to Skin‐Borne Bacterial Adhesion

There is a growing quest for an ideal biomaterial that shows appropriate cellular response and is not susceptible to microbial adhesion. In this study, commercial grade II titanium was submitted to RF/DC plasma surface modification at 2.2 mbar, using gas mixtures of argon, nitrogen, and oxygen at proportions 4:1:2 and 4:1:3. The surfaces were physically and chemically characterized. In order to evaluate bacterial response, the surfaces were exposed to Staphylococcus epidermidis. Oxynitrided samples, although having a higher roughness as compared with untreated samples, exhibited lower bacterial growth. This observation is probably due to the formation of different crystalline phases of nitrides and oxides caused by plasma treatment. The surface with highest contact angle and highest surface tension showed lower bacterial adhesion. These results were confirmed by scanning electron microscopy. The role of nitrogen in reducing bacterial adhesion is clear when this material is compared with untreated titanium, on which only an oxide film is present.