👤 Sabine Bahn

Alzheimer's disease (AD) is marked by amyloid-β (Aβ) accumulation, tau pathology, and neuroinflammation. The β-site APP cleaving enzyme 1 (BACE1) is a key driver of Aβ production, while the NLRP3 inflammasome mediates microglial inflammatory responses. Histone deacetylase 6 (HDAC6), a cytoplasmic deacetylase, is upregulated in AD, yet its role in disease mechanisms remains unclear. Here, we show that HDAC6 promotes BACE1 protein stability through direct deacetylation of its C-terminal lysine (K501), thereby increasing Aβ production. HDAC6 also facilitated NLRP3 inflammasome activation in microglia, increasing IL-1β production in a catalytic domain-dependent manner. HDAC6 deficiency in 5xFAD mice reduced BACE1 accumulation, Aβ deposition, ASC speck formation, and IL-1β levels, accompanied by improved cognitive performance. Transcriptomic profiling further revealed downregulation of disease-associated microglial and neurotoxic astrocyte signatures alongside enrichment of synaptic pathways. These findings establish HDAC6 as a dual regulator of Aβ production and neuroinflammation, highlighting it as a promising therapeutic target in AD. Show less

Antidepressant treatment for major depressive disorder remains suboptimal with response rates of just over 50%. Although treatment guidelines, algorithms and clinical keys are available to assist the clinician, the process of finding an effective pharmacotherapy to maximise benefit for the individual patient is largely by "trial and error" and remains challenging. This highlights a clear need to identify biomarkers of treatment response to help guide personalised treatment strategies. We have carried out the largest multiplex immunoassay based longitudinal study to date, examining up to 258 serum markers involved in immune, endocrine and metabolic processes as potential biomarkers associated with treatment response in 332 depression patients recruited from four independent clinical centres. We demonstrated for the first time that circulating Apolipoprotein A-IV, Endoglin, Intercellular Adhesion Molecule 1, Tissue Inhibitor of Metalloproteinases 1, Plasminogen Activator Inhibitor 1, Thrombopoietin, Complement C3, Hepatocyte Growth Factor and Insulin-like Growth Factor-Binding Protein 2 were associated with response to different antidepressants. In addition, we showed that specific sets of immune-endocrine proteins were associated with response to Venlafaxine (serotonin-norepinephrine reuptake inhibitor), Imipramine (tricyclic antidepressant) and other antidepressant drugs. However, we were not able to reproduce the literature findings on BDNF and TNF-α, two of the most commonly reported candidate treatment response markers. Despite the need for extensive validation studies, our preliminary findings suggest that a pre-treatment immune-endocrine profile may help to determine a patient's likelihood to respond to specific antidepressant and/or alternative treatments such as anti-inflammatory drugs, providing hope for future personalised treatment approaches. Show less

Previous studies have shown that blood serum phosphoproteins are altered in schizophrenia patients in comparison to controls. However, it is not known whether phosphoproteins are also changed in response to treatment with antipsychotics. Blood samples were taken from patients (n = 23) at baseline and after 6 weeks of olanzapine treatment. Immobilized metal ion affinity chromatography (IMAC) was used for enrichment of serum phosphoproteins and these were analyzed by label-free LC-MS in expression mode (LC-MS(E) ). We identified 11 proteins that were changed significantly in overall abundance and 45 proteins that showed changes in phosphorylation after the antipsychotic treatment. The altered phosphoproteins were mainly involved in the acute phase response, lipid and glucose homeostasis (LXR), retinoic acid signaling (RXR), and complement pathways. Some of the proteins showed a marked increase in phosphorylation, including apolipoprotein A-I (3.4-fold), alpha-1-anti-chymotrypsin (3.1-fold), and apolipoprotein B-100 (2.2-fold). In addition, several proteins showed either decreased phosphorylation (e.g. complement C4A, collagen alpha-1 chain, complement factor H) or a mixture of increased and decreased phoshphorylation (e.g. afamin, complement C5, complement factor B). Finally, 24 of the altered phosphoproteins showed opposite directional changes in a comparison of baseline schizophrenia patients before and after treatment with olanzapine. These included alpha-1B-glycoprotein, apolipoprotein A-IV, vitamin D-binding protein, and prothrombin. These data demonstrate the potential for future studies of serum phosphoproteins as a readout of physiological function and might have utility in studies aimed at identification of biomarkers for drug response prediction or monitoring. Show less