👤 Sylke Kurz

Early and accurate detection of Alzheimer's disease (AD) is essential for timely intervention and development of disease-modifying treatments. The DZNE-Longitudinal Cognitive Impairment and Dementia Study (DELCODE) provides a deeply phenotyped cohort covering preclinical and early clinical stages, including subjective cognitive decline (SCD) and mild cognitive impairment (MCI). Astrocyte reactivity and its biomarkers, particularly glial fibrillary acidic protein (GFAP), have gained increasing attention in AD research; however, the relationship between GFAP and amyloid in early disease, as well as its potential prognostic value beyond its association with amyloid status, remains insufficiently understood. To evaluate the performance of CSF and plasma GFAP across early disease stages, compare these measures according to amyloid status, and assess the prognostic value of GFAP for clinical progression across diagnostic stages during longitudinal follow-up. This study used data from the multicenter DELCODE cohort in Germany, including participants with available plasma and/or CSF samples and standardized clinical, cognitive, imaging, and biomarker assessments. GFAP concentrations in plasma and CSF were quantified using validated immunoassay platforms. Standard CSF AD biomarkers and ApoE genotype were measured using established assays. Amyloid status was defined by the CSF Aβ42/40 ratio. Longitudinal follow-up occurred annually for up to ∼10 years, with clinical conversion determined according to NIA-AA criteria. Plasma and CSF GFAP increased across the AD continuum, with higher levels in MCI and AD (p < 0.001). Plasma GFAP showed a stronger association with amyloid status than CSF GFAP across all groups. In MCI, plasma GFAP combined with age and ApoE4 yielded an AUC of 0.87. Elevated plasma GFAP predicted increased risk of conversion to MCI (HR = 2.19, p < 0.001; adjusted HR = 1.70, p = 0.0056) and AD dementia (HR = 3.5; adjusted HR = 2.49 both p < 0.001). Plasma GFAP is a sensitive, minimally invasive biomarker with diagnostic relevance for amyloid detection and prognostic relevance for clinical progression in early AD. Show less

Macrophages express numerous G protein-coupled receptors (GPCRs) that regulate adhesion, migration, and activation, but the function of orphan receptor GPRC5B in macrophages is unknown. Both resident peritoneal and bone marrow-derived macrophages from myeloid-specific GPRC5B-deficient mice show increased migration and phagocytosis, resulting in improved bacterial clearance in a peritonitis model. In other models such as myocardial infarction, increased myeloid cell recruitment has adverse effects. Mechanistically, we found that GPRC5B physically interacts with GPCRs of the prostanoid receptor family, resulting in enhanced signaling through the prostaglandin E receptor 2 (EP2). In GPRC5B-deficient macrophages, EP2-mediated anti-inflammatory effects are diminished, resulting in hyperactivity. Using in silico modelling and docking, we identify residues potentially mediating GPRC5B/EP2 dimerization and show that their mutation results in loss of GPRC5B-mediated facilitation of EP2 signaling. Finally, we demonstrate that decoy peptides mimicking the interacting sequence are able to reduce GPRC5B-mediated facilitation of EP2-induced cAMP signaling in macrophages. Show less

Checkpoint-inhibitor pneumonitis (CIP) represents a major immune-related adverse event (irAE) in patients with lung cancer. We aimed for the clinical characterization, diagnostics, risk factors, treatment and outcome in a large cohort of patients from everyday clinical practice. For this retrospective analysis, 1,376 patients having received checkpoint inhibitors (CPI) in any line of therapy from June 2015 until February 2020 from three large-volume lung cancer centers in Berlin, Germany were included and analyzed. With a median follow-up of 35 months, all-grade, high-grade (CTCAE ≥ 3) and fatal CIP were observed in 83 (6.0%), 37 (2.7%) and 12 (0.9%) patients, respectively, with a median onset 4 months after initiation of CPI therapy. The most common radiologic patterns were organizing pneumonia (OP) and non-specific interstitial pneumonia (NSIP) (37% and 31%). All except 7 patients with G1-2 CIP interrupted treatment. Corticosteroids were administered to 74 patients with a median starting dose of 0.75 mg/kg. After complete restitution (n = 67), re-exposure to CPI (n = 14) led to additional irAE in 43% of the cases. Thoracic radiotherapy targeting the lung was the only independent risk factor for CIP (odds ratio 2.8, p < 0.001) and pretherapeutic diffusing capacity for carbon monoxide inversely correlated with CIP severity. Compared with patients without CIP and non-CIP irAE, CIP was associated with impaired overall survival (hazard ratios 1.23, p = 0.24 and 2.01, p = 0.005). High-grade CIP accounts for almost half of all CIP cases in an allcomer lung cancer population. A continuous vigilance, rapid diagnostics and adequate treatment are key to prevent disease progression associated with impaired survival. Show less

G protein-coupled receptors are important regulators of contractility and differentiation in vascular smooth muscle cells (SMCs), but the specific function of SMC-expressed orphan G protein-coupled receptor class C group 5 member B (GPRC5B) is unclear. We studied the role of GPRC5B in the regulation of contractility and dedifferentiation in human and murine SMCs in vitro and in iSM- Mesenteric arteries from SMC-specific Taken together, our data show that GPRC5B regulates vascular SMC tone and differentiation by negatively regulating IP signaling. Show less

Coordinated reorganization of cytoskeletal structures is critical for key aspects of platelet physiology. While several studies have addressed the role of microtubules and filamentous actin in platelet production and function, the significance of their crosstalk in these processes has been poorly investigated. The microtubule-actin cross-linking factor 1 (MACF1; synonym: Actin cross-linking factor 7, ACF7) is a member of the spectraplakin family, and one of the few proteins expressed in platelets, which possess actin and microtubule binding domains thereby facilitating actin-microtubule interaction and regulation. We used megakaryocyte- and platelet-specific Macf1 knockout (Macf1 Show less