Age and Chronodisruption in Mouse Heart: Effect of the NLRP3 Inflammasome and Melatonin Therapy.

Age and age-dependent inflammation are two main risk factors for cardiovascular diseases. Aging can also affect clock gene-related impairments such as chronodisruption and has been linked to a decline in melatonin synthesis and aggravation of the NF-κB/NLRP3 innate immune response known as inflammaging. The molecular drivers of these mechanisms remain unknown. This study investigated the impact of aging and NLRP3 expression on the cardiac circadian system, and the actions of melatonin as a potential therapy to restore daily rhythms by mitigating inflammaging. We analyzed the circadian expression and rhythmicity of clock genes in heart tissue of wild-type and NLRP3-knockout mice at 3, 12, and 24 months of age, with and without melatonin treatment. Our results support that aging, NLRP3 inflammasome, and melatonin affected the cardiac clock genes expression, except for Rev-erbα, which was not influenced by genotype. Aging caused small phase changes in Clock, loss of rhythmicity in Per2 and Rorα, and mesor dampening of Clock, Bmal1, and Per2. NLRP3 inflammasome influenced the acrophase of Clock, Per2, and Rorα. Melatonin restored the acrophase and the rhythm of clock genes affected by age or NLRP3 activation. The administration of melatonin re-established murine cardiac homeostasis by reversing age-associated chronodisruption. Altogether, these results highlight new findings about the effects aging and NLRP3 inflammasome have on clock genes in cardiac tissue, pointing to continuous melatonin as a promising therapy to placate inflammaging and restore circadian rhythm in heart muscle. Additionally, light microscopy analysis showed age-related morphological impairments in cardiomyocytes, which were less severe in mice lacking NLRP3. Melatonin supplementation preserved the structure of cardiac muscle fibers in all experimental groups.

Daily Changes in the Expression of Clock Genes in Sepsis and Their Relation with Sepsis Outcome and Urinary Excretion of 6-Sulfatoximelatonin.

BACKGROUND: Whereas the circadian system controls the daily production of melatonin and the daily activity of the immune system, increasing evidences support the association between circadian misalignment with the alterations in the immune response and melatonin rhythm during sepsis. The aim of this study was to analyze the daily changes in clock genes expression and the urinary excretion of 6-SM (6-sulfatoxymelatonin, the major melatonin metabolite), and their connection with the innate immune activity, oxidative status in blood, and clinical outcome during sepsis. METHODS: Healthy volunteers, non-septic intensive care unit (ICU) patients, and septic ICU patients, were evaluated. The expression of bmal1, per2, clock, and cry1 genes was determined by polymerase chain reaction in blood; 6-SM was assessed in urine by ELISA; plasma cytokines IL-1ß, IL-6, IL-8, TNFα, and IL-10 were determined by a multiplex array method, and lipid peroxidation (LPO) and protein oxidation (AOPP) by spectrophotometry. Hematological and biochemical data, and clinical scores of the patients, were also recorded. RESULTS: Clock gene rhythm was maintained in non-septic patients but blunted in septic ones, whereas the innate immune and the oxidative stress responses were significantly higher in the latter. 6-SM excretion was also more elevated in septic than in non-septic patients, and it correlated with the degree of the immune response and oxidative status. 6-SM also correlated with SOFA and procalcitonin in the patients. Proinflammatory cytokines, LPO, and AOPP were normalized in the patients once recovered from sepsis. CONCLUSION: Our data suggest a relationship between clock genes rhythm disruption, the immune response, and the oxidative status, with 6-SM acting as a compensatory response. ICU conditions are not a main clock disrupter because of the significant differences found in the responses of septic versus non-septic patients under the same ICU environment.