Binding of the radioligand SIL23 to alpha-synuclein fibrils in Parkinson disease brain tissue establishes feasibility and screening approaches for developing a Parkinson disease imaging agent

Accumulation of α-synuclein (α-syn) fibrils in Lewy bodies and Lewy neurites is the pathological hallmark of Parkinson disease (PD). Ligands that bind α-syn fibrils could be utilized as imaging agents to improve the diagnosis of PD and to monitor disease progression. However, ligands for α-syn fibrils in PD brain tissue have not been previously identified and the feasibility of quantifying α-syn fibrils in brain tissue is unknown. We report the identification of the (125)I-labeled α-syn radioligand SIL23. [(125)I]SIL23 binds α-syn fibrils in postmortem brain tissue from PD patients as well as an α-syn transgenic mouse model for PD. The density of SIL23 binding sites correlates with the level of fibrillar α-syn in PD brain tissue, and [(125)I]SIL23 binding site densities in brain tissue are sufficiently high to enable in vivo imaging with high affinity ligands. These results identify a SIL23 binding site on α-syn fibrils that is a feasible target for development of an α-syn imaging agent. The affinity of SIL23 for α-syn and its selectivity for α-syn versus Aβ and tau fibrils is not optimal for imaging fibrillar α-syn in vivo, but we show that SIL23 competitive binding assays can be used to screen additional ligands for suitable affinity and selectivity, which will accelerate the development of an α-syn imaging agent for PD

A new model for diabetes-focused capacity building – lessons from Sri Lanka

Abstract Sri Lanka is experiencing a rapid increase in the number of people with diabetes mellitus (DM) due to population growth and aging. Physician shortages, outdated technology, and insufficient health education have contributed to the difficulties associated with managing the burden of disease. New models of chronic disease management are needed to address the increasing prevalence of DM. Medical students, business students, and faculty members from the University of Michigan partnered with the Grace Girls’ Home, Trincomalee General Hospital, and Selvanayakapuram Central Hospital to identify and train diabetes-focused medical assistants (MAs) to collect and enter patient data and educate patients about their disease. Return visits to these MAs were encouraged so that patient progress and disease progression could be tracked longitudinally. Data entry was conducted through a cloud-based mechanism, facilitating patient management and descriptive characterization of the population. We implemented this pilot program in June 2016 in coordination with Trincomalee General Hospital and Selvanayakapuram Central Hospital. Over a 12-month period, 93 patients were systematically assessed by the medical assistants. All patients received education and were provided materials after the visit to better inform them about the importance of controlling their disease. Fifteen percent (14/93) of patients returned for follow-up consultation. Trained MAs have the potential to provide support to physicians working in congested health systems in low-resource settings. Public investment in training programs for MAs and greater acceptance by physicians and patients will be essential for handling the growing burden associated with chronic illnesses like DM. Trained MAs may also play a role in improved patient education and awareness regarding diabetes self-management.https://deepblue.lib.umich.edu/bitstream/2027.42/146742/1/40842_2018_Article_74.pd

Constitutive bone marrow adipocytes suppress local bone formation

Bone marrow adipocytes (BMAd) are a unique cell population derived from bone marrow mesenchymal progenitors and marrow adipogenic lineage precursors. Although they have long been considered to be a space-filler within bone cavities, recent studies have revealed important physiological roles in hematopoiesis and bone metabolism. To date, the approaches used to study BMAd function have been confounded by contributions by non-marrow adipocytes or by bone marrow stromal cells. To address this gap in the field, we have developed a BMAd-specific Cre mouse model to deplete BMAds by expression of diphtheria toxin A (DTA), or by deletion of peroxisome proliferator-activated receptor gamma (Pparg). We found that DTA-induced loss of BMAds results in decreased hematopoietic stem and progenitor cell numbers and increased bone mass in BMAd-enriched locations, including the distal tibiae and caudal vertebrae. Elevated bone mass appears to be secondary to enhanced endosteal bone formation, suggesting a local effect caused by depletion of BMAd. Augmented bone formation with BMAd-depletion protects mice from bone loss induced by caloric restriction or ovariectomy, and facilitates the bone healing process after fracture. Finally, ablation of Pparg also reduces BMAd numbers and largely recapitulates high bone mass phenotypes observed with DTA-induced BMAd depletion

Lactational High-Fat Diet Exposure Programs Metabolic Inflammation and Bone Marrow Adiposity in Male Offspring

Overnutrition during critical windows of development plays a significant role in life-long metabolic disease risk. Early exposure to excessive nutrition may result in altered programming leading to increased susceptibility to obesity, inflammation, and metabolic complications. This study investigated the programming effects of high-fat diet (HFD) exposure during the lactation period on offspring adiposity and inflammation. Female C57Bl/6J dams were fed a normal diet or a 60% HFD during lactation. Offspring were weaned onto a normal diet until 12 weeks of age when half were re-challenged with HFD for 12 weeks. Metabolic testing was performed throughout adulthood. At 24 weeks, adipose depots were isolated and evaluated for macrophage profiling and inflammatory gene expression. Males exposed to HFD during lactation had insulin resistance and glucose intolerance as adults. After re-introduction to HFD, males had increased weight gain and worsened insulin resistance and hyperglycemia. There was increased infiltration of pro-inflammatory CD11c+ adipose tissue macrophages, and bone marrow was primed to produce granulocytes and macrophages. Bone density was lower due to enhanced marrow adiposity. This study demonstrates that maternal HFD exposure during the lactational window programs offspring adiposity, inflammation, and impaired glucose homeostasis

Binding of the Radioligand SIL23 to α-Synuclein Fibrils in Parkinson Disease Brain Tissue Establishes Feasibility and Screening Approaches for Developing a Parkinson Disease Imaging Agent

<div><p>Accumulation of α-synuclein (α-syn) fibrils in Lewy bodies and Lewy neurites is the pathological hallmark of Parkinson disease (PD). Ligands that bind α-syn fibrils could be utilized as imaging agents to improve the diagnosis of PD and to monitor disease progression. However, ligands for α-syn fibrils in PD brain tissue have not been previously identified and the feasibility of quantifying α-syn fibrils in brain tissue is unknown. We report the identification of the ¹²⁵I-labeled α-syn radioligand SIL23. [¹²⁵I]SIL23 binds α-syn fibrils in postmortem brain tissue from PD patients as well as an α-syn transgenic mouse model for PD. The density of SIL23 binding sites correlates with the level of fibrillar α-syn in PD brain tissue, and [¹²⁵I]SIL23 binding site densities in brain tissue are sufficiently high to enable <em>in vivo</em> imaging with high affinity ligands. These results identify a SIL23 binding site on α-syn fibrils that is a feasible target for development of an α-syn imaging agent. The affinity of SIL23 for α-syn and its selectivity for α-syn versus Aβ and tau fibrils is not optimal for imaging fibrillar α-syn <em>in vivo</em>, but we show that SIL23 competitive binding assays can be used to screen additional ligands for suitable affinity and selectivity, which will accelerate the development of an α-syn imaging agent for PD.</p> </div

Comparison of K_i values for SIL analogues in assays with α-syn, Aβ_1–42, and tau fibrils illustrates relative selectivity for α-syn over Aβ_1–42 and tau.

<p>K_i values were calculated from EC₅₀ values using the equation K_i = EC₅₀/(1+[radioligand]/K_d). 95% confidence intervals for K_i values are shown in parentheses.</p

[¹²⁵I]SIL23 exhibits specific binding to insoluble protein from human PD brain samples but not control human brain samples.

<p>Homogenized insoluble fractions from human brain samples (n = 8) were incubated with increasing concentrations of [¹²⁵I]SIL23. Nonspecific binding was determined in parallel reactions utilizing 50 µM ThioT as competitor. Representative plots of specific binding versus [¹²⁵I]SIL23 concentration are shown. <b>A–D</b> show four different PD cases and <b>E–H</b> show four control cases. The data was analyzed by curve fitting to a one-site binding model using nonlinear regression. K_d values for binding to PD-dementia brain samples range from 119.1 nM to 168.3 nM and B_max values range from 13–25 pmol/mg insoluble protein. No significant binding of [¹²⁵I]SIL23 to control samples was observed. Results were verified with at least two independent experiments.</p