👤 M Nieuwdorp

Despite available therapies for depression, many patients do not achieve adequate improvement, illustrating the need for innovative treatment strategies. Nutritional psychiatry is an emerging area, with increasing evidence that microbially derived butyrate contributes to the beneficial effects of dietary, pre-, pro- and synbiotics interventions - raising the exciting possibility that direct butyrate administration might alleviate depressive symptoms. The main objective was to systematically review the effects of butyrate on depressive symptoms in humans and depressive-like behavior in animals (PROSPERO; CRD42023g0739). A search was conducted in MEDLINE, Embase, PsycINFO, and Web of Science, ICTPR and ClinicalTrials.gov up to October 2025. Studies were included if they examined depressive symptoms in humans or relevant behaviors in animal models of depression/anxiety, involved treatment with butyrate formulations, included a control or pre-post comparison, and reported behavioral or clinical outcomes. Eligible designs included case-control, cohort, (randomized) controlled trials, experimental, or in vivo studies published in English or Dutch. Studies were excluded if depression was not the primary focus or if butyrate was combined with another treatment. Risk of bias was assessed with SYRCLE for animal studies and RoB 2 for the human studies. Of the two randomized controlled trials, one found no measurable effect of 1-week oral butyrate in healthy males, whereas the other found reductions in depressive and anxiety symptoms in patients with ulcerative colitis after 12-weeks oral butyrate. Thirty-two animal studies showed that butyrate generally modulated depressive- and anxiety-like phenotypes in rodents, potentially via anti-inflammatory, neuroplastic, epigenetic and gut-mediated mechanisms. Preclinical findings support the therapeutic promise of butyrate as a novel intervention for depression, warranting further clinical investigation. BDNF, Brain-derived neurotrophic factor; CRS, Chronic restraint stress; CSD, Chronic social defeat; CUMS, Chronic unpredictable mild stress; DASS, Depression, anxiety, Stress Scales; EPM, Elevated plus maze; FMT, Fecal microbiota transplant; FST, Forced swim test; HDAC, Histone deacetylase; HFD, High-fat diet; HPA, Hypothalamic-pituitary-adrenal; ICTRP International Clinical Trials Registry Platform; IL, Interleukin; LDB, Light-dark box; LEIDS-R, Leiden Index of Depression Severity-Revised; LPS, Lipopolysaccharide; MD, Maternal deprivation; MDD, Major depressive disorder; MGBA, Microbiota-gut-brain axis; NORT, Novel object recognition test; OFT, Open field test; PFC, Prefrontal cortex; PRISMA Preferred reporting items for systematic reviews and meta-analyses; SCFA, Short-chain fatty acid; SPT, Sucrose preference test; SYRCLE, Systematic Review Centre for Laboratory Animal Experimentation; TCA, Tricarboxylic acid; TNF, Tumor necrosis factor; TST, Tail suspension test; ZO-1, Zonulin-1. Show less

Akkermansia muciniphila (A. muciniphila) is an intestinal commensal with anti-inflammatory properties both in the intestine and other organs. The aim is to investigate the effects of oral administration of A. muciniphila on lipid metabolism, immunity, and cuff-induced neointima formation in hyperlipidemic APOE*3-Leiden (E3L).CETP mice. Hyperlipidemic male E3L.CETP mice are daily treated with 2 × 10 Four weeks of treatment with A. muciniphila exerts lipid-lowering and immunomodulatory effects, which are insufficient to inhibit neointima formation in hyperlipidemic E3L.CETP mice. Show less

Elevated nonfasting TG-rich lipoprotein levels are a risk factor for CVD. To further evaluate the relevance of LDL-receptor (LDLr) pathway and heparan sulfate proteoglycans (HSPGs) in TG homeostasis, we analyzed fasting and postprandial TG levels in mice bearing combined heterozygous mutations in both Exostosin (Ext) 1 and Ldlr, in subjects with hereditary multiple exostosis (HME) due to a heterozygous loss-of-function mutation in EXT1 or EXT2 (N = 13), and in patients with heterozygous mutations in LDLR [familial hypercholesterolemia (FH)] and SNPs in major HSPG-related genes (n = 22). Mice bearing a homozygous mutation in hepatic Ext1 exhibited elevated plasma TGs similar to mice lacking other key enzymes involved in HSPG assembly. Compound heterozygous mice lacking Ldlr and Ext1 showed synergy on plasma TG accumulation and postprandial clearance. In human subjects, a trend was observed in HME patients toward reduced postprandial TG clearance with a concomitant reduction in chylomicron clearance [area under the curve (AUC)-retinyl ester (RE) HME, 844 ± 127 vs. controls, 646 ± 119 nM/h, P = 0.09]. Moreover, in FH subjects with a high HSPG gene score, retinyl palmitate excursions were higher (AUC-RE, 2,377 ± 293 vs. 1,565 ± 181 nM/h, P < 0.05). Incremental AUC-apoB48 was similar between the groups. In conclusion, the data are supportive for a minor yet additive role of HSPG in human postprandial TG clearance, and further studies are warranted. Show less

Exotosin (EXT) proteins are involved in the chain elongation step of heparan sulfate (HS) biosynthesis, which is intricately involved in organ development. Loss of function mutations (LOF) in EXT1 and EXT2 result in hereditary exostoses (HME). Interestingly, HS plays a role in pancreas development and beta-cell function, and genetic variations in EXT2 are associated with an increased risk for type 2 diabetes mellitus. We hypothesized that loss of function of EXT1 or EXT2 in subjects with hereditary multiple exostoses (HME) affects pancreatic insulin secretion capacity and development. We performed an oral glucose tolerance test (OGTT) followed by hyperglycemic clamps to investigate first-phase glucose-stimulated insulin secretion (GSIS) in HME patients and age and gender matched non-affected relatives. Pancreas volume was assessed with magnetic resonance imaging (MRI). OGTT did not reveal significant differences in glucose disposal, but there was a markedly lower GSIS in HME subjects during hyperglycemic clamp (iAUC HME: 0.72 [0.46-1.16] vs. controls 1.53 [0.69-3.36] nmol·l-1·min-1, p<0.05). Maximal insulin response following arginine challenge was also significantly attenuated (iAUC HME: 7.14 [4.22-10.5] vs. controls 10.2 [7.91-12.70] nmol·l-1·min-1 p<0.05), indicative of an impaired beta-cell reserve. MRI revealed a significantly smaller pancreatic volume in HME subjects (HME: 72.0±15.8 vs. controls 96.5±26.0 cm3 p = 0.04). In conclusion, loss of function of EXT proteins may affect beta-cell mass and insulin secretion capacity in humans, and render subjects at a higher risk of developing type 2 diabetes when exposed to environmental risk factors. Show less

Heparanase is the major enzyme involved in degradation of endothelial heparan sulfates, which is associated with impaired endothelial nitric oxide synthesis. However, the effect of heparan sulfate chain length in relation to endothelial function and nitric oxide availability has never been investigated. We studied the effect of heterozygous mutations in heparan sulfate elongation genes EXT1 and EXT2 on endothelial function in vitro as well as in vivo. Flow-mediated dilation, a marker of nitric oxide bioavailability, was studied in Ext1(+/-) and Ext2(+/-) mice versus controls (n=7 per group), as well as in human subjects with heterozygous loss of function mutations in EXT1 and EXT2 (n=13 hereditary multiple exostoses and n=13 controls). Endothelial function was measured in microvascular endothelial cells under laminar flow with or without siRNA targeting EXT1 or EXT2. Endothelial glycocalyx and maximal arteriolar dilatation were significantly altered in Ext1(+/-) and Ext2(+/-) mice compared to wild-type littermates (glycocalyx: wild-type 0.67±0.1 μm, Ext1(+/-) 0.28±0.1 μm and Ext2(+/-) 0.25±0.1 μm, P<0.01, maximal arteriolar dilation during reperfusion: wild-type 11.3±1.0%), Ext1(+/-) 15.2±1.4% and Ext2(+/-) 13.8±1.6% P<0.05). In humans, brachial artery flow-mediated dilation was significantly increased in hereditary multiple exostoses patients (hereditary multiple exostoses 8.1±0.8% versus control 5.6±0.7%, P<0.05). In line, silencing of microvascular endothelial cell EXT1 and EXT2 under flow led to significant upregulation of endothelial nitric oxide synthesis and phospho-endothelial nitric oxide synthesis protein expression. Our data implicate that heparan sulfate elongation genes EXT1 and EXT2 are involved in maintaining endothelial homeostasis, presumably via increased nitric oxide bioavailability. Show less