Lower serum ferritin levels are associated with worse cognitive performance in aging.

OBJECTIVES: Iron is important for neurogenesis, synaptic development, and neurotransmitter synthesis. Serum ferritin (SF) is a reliable marker for assessing iron stores. Therefore, we evaluated the cognitive function associated with SF levels. We also assessed brain iron content using R2* Magnetic Resonance Imaging (MRI) and its association with SF levels. DESIGN: Data from three cross-sectional observational studies were used. Aging Imageomics (n = 1030) was conducted on aged subjects. Health Imageomics (n = 971) and IR0NMET (n = 175) were conducted in middle-aged subjects. SETTING AND PARTICIPANTS: Participants were enrolled at Dr. Josep Trueta University Hospital facilities. The three cohorts included a total of 2176 subjects (mean age, 52 years; 48% men). MEASUREMENTS: SF levels were measured by standard laboratory methods. Total Digits Span (TDS), and Phonemic Verbal Fluency (PVF) were used to assess executive function. Language function was assessed by semantic verbal fluency (SVF), attention by the Symbol Digit Modalities Test, and memory by the Memory Binding Tests - Total Free Recall and Total Delayed Free Recall. MRI was used to assess the iron content of the brain by R2*. RESULTS: In subjects aged 65 years or older, SF levels were associated with increased TDS (ß = 0.003, p = 0.02), PVF (ß = 0.004, p = 0.01), and SVF (ß = 0.004, p = 0.002) scores. After stratification by sex, these findings were significant only in men, where SF was associated with increased TDS (ß = 0.003, p = 0.01), PVF (ß = 0.004, p = 0.03), and SVF (ß = 0.004, p = 0.009) scores. In middle-aged subjects, SF was also associated with increased SVF scores (ß = 0.005, p = 0.011). Lastly, in men, SF levels were negatively associated with R2*, a surrogate marker of brain iron content, in both the left frontal inferior opercular area (r = -0.41, p = 0.005) and the right frontal inferior opercular area (r = -0.44, p = 0.002). CONCLUSIONS: SF is significantly and positively associated with cognition. In older people with low SF levels, iron supplementation may be a promising therapy to improve cognition.

Microbiota alterations in proline metabolism impact depression.

The microbiota-gut-brain axis has emerged as a novel target in depression, a disorder with low treatment efficacy. However, the field is dominated by underpowered studies focusing on major depression not addressing microbiome functionality, compositional nature, or confounding factors. We applied a multi-omics approach combining pre-clinical models with three human cohorts including patients with mild depression. Microbial functions and metabolites converging onto glutamate/GABA metabolism, particularly proline, were linked to depression. High proline consumption was the dietary factor with the strongest impact on depression. Whole-brain dynamics revealed rich club network disruptions associated with depression and circulating proline. Proline supplementation in mice exacerbated depression along with microbial translocation. Human microbiota transplantation induced an emotionally impaired phenotype in mice and alterations in GABA-, proline-, and extracellular matrix-related prefrontal cortex genes. RNAi-mediated knockdown of proline and GABA transporters in Drosophila and mono-association with L. plantarum, a high GABA producer, conferred protection against depression-like states. Targeting the microbiome and dietary proline may open new windows for efficient depression treatment.

Iron status influences non-alcoholic fatty liver disease in obesity through the gut microbiome.

BACKGROUND: The gut microbiome and iron status are known to play a role in the pathophysiology of non-alcoholic fatty liver disease (NAFLD), although their complex interaction remains unclear. RESULTS: Here, we applied an integrative systems medicine approach (faecal metagenomics, plasma and urine metabolomics, hepatic transcriptomics) in 2 well-characterised human cohorts of subjects with obesity (discovery n = 49 and validation n = 628) and an independent cohort formed by both individuals with and without obesity (n = 130), combined with in vitro and animal models. Serum ferritin levels, as a markers of liver iron stores, were positively associated with liver fat accumulation in parallel with lower gut microbial gene richness, composition and functionality. Specifically, ferritin had strong negative associations with the Pasteurellaceae, Leuconostocaceae and Micrococcaea families. It also had consistent negative associations with several Veillonella, Bifidobacterium and Lactobacillus species, but positive associations with Bacteroides and Prevotella spp. Notably, the ferritin-associated bacterial families had a strong correlation with iron-related liver genes. In addition, several bacterial functions related to iron metabolism (transport, chelation, heme and siderophore biosynthesis) and NAFLD (fatty acid and glutathione biosynthesis) were also associated with the host serum ferritin levels. This iron-related microbiome signature was linked to a transcriptomic and metabolomic signature associated to the degree of liver fat accumulation through hepatic glucose metabolism. In particular, we found a consistent association among serum ferritin, Pasteurellaceae and Micrococcacea families, bacterial functions involved in histidine transport, the host circulating histidine levels and the liver expression of GYS2 and SEC24B. Serum ferritin was also related to bacterial glycine transporters, the host glycine serum levels and the liver expression of glycine transporters. The transcriptomic findings were replicated in human primary hepatocytes, where iron supplementation also led to triglycerides accumulation and induced the expression of lipid and iron metabolism genes in synergy with palmitic acid. We further explored the direct impact of the microbiome on iron metabolism and liver fact accumulation through transplantation of faecal microbiota into recipient's mice. In line with the results in humans, transplantation from 'high ferritin donors' resulted in alterations in several genes related to iron metabolism and fatty acid accumulation in recipient's mice. CONCLUSIONS: Altogether, a significant interplay among the gut microbiome, iron status and liver fat accumulation is revealed, with potential significance for target therapies. Video abstract.

Activation of Endogenous H2S Biosynthesis or Supplementation with Exogenous H2S Enhances Adipose Tissue Adipogenesis and Preserves Adipocyte Physiology in Humans.

Aims: To investigate the impact of exogenous hydrogen sulfide (H2S) and its endogenous biosynthesis on human adipocytes and adipose tissue in the context of obesity and insulin resistance. Results: Experiments in human adipose tissue explants and in isolated preadipocytes demonstrated that exogenous H2S or the activation of endogenous H2S biosynthesis resulted in increased adipogenesis, insulin action, sirtuin deacetylase, and PPARγ transcriptional activity, whereas chemical inhibition and gene knockdown of each enzyme generating H2S (CTH, CBS, MPST) led to altered adipocyte differentiation, cellular senescence, and increased inflammation. In agreement with these experimental data, visceral and subcutaneous adipose tissue expression of H2S-synthesising enzymes was significantly reduced in morbidly obese subjects in association with attenuated adipogenesis and increased markers of adipose tissue inflammation and senescence. Interestingly, weight-loss interventions (including bariatric surgery or diet/exercise) improved the expression of H2S biosynthesis-related genes. In human preadipocytes, the expression of CTH, CBS, and MPST genes and H2S production were dramatically increased during adipocyte differentiation. More importantly, the adipocyte proteome exhibiting persulfidation was characterized, disclosing that different proteins involved in fatty acid and lipid metabolism, the citrate cycle, insulin signaling, several adipokines, and PPAR, experienced the most dramatic persulfidation (85-98%). Innovation: No previous studies investigated the impact of H2S on human adipose tissue. This study suggests that the potentiation of adipose tissue H2S biosynthesis is a possible therapeutic approach to improve adipose tissue dysfunction in patients with obesity and insulin resistance. Conclusion: Altogether, these data supported the relevance of H2S biosynthesis in the modulation of human adipocyte physiology. Antioxid. Redox Signal. 35, 319-340.

Clinical and economic impact of the taurolidine lock on home parenteral nutrition.

INTRODUCTION: catheter-related bloodstream infections (CRBSI) are one of the most serious concerns in patients on home parenteral nutrition (HPN) which involve high morbidity and cost for the healthcare system. In the last years, taurolidine lock has proven to be beneficial in the prevention of CRBSI; however, the evidence of its efficiency is limited. OBJECTIVE: to determine if taurolidine lock is a cost-effective intervention in patients on HPN. MATERIALS AND METHODS: retrospective study in patients on HPN with taurolidine lock. We compared the CRBSI rate and cost of its complications before and during taurolidine lock. RESULTS: thirteen patients, six (46%) males and seven (54%) females, with a mean age of 61.08 (SD = 14.18) years received taurolidine lock. The total days of catheterization pre and per-taurolidine were 12,186 and 5,293, respectively. The underlying disease was benign in five patients (38.5%) and malignant in eight (61.5%). The CRBSI rate pre vs per-taurolidine was 3.12 vs 0.76 episodes per 1,000 catheter days (p = 0.0058). When the indication was a high CRBSI rate, this was 9.72 vs 0.39 (p < 0.001) in pre and per-taurolidine period respectively. No differences have been observed in the occlusion rates. None of the patients reported any adverse effects. The total cost of CRBSI in the pre-taurolidine period was 151,264.14 euros vs 24,331.19 euros in the per-taurolidine period. CONCLUSIONS: our study shows that taurolidine lock is a cost-effective intervention in patients on HPN with high risk of CRBSI.