Development and Optimization of a Target Engagement Model of Brain IDO Inhibition for Alzheimer's Disease.

BACKGROUND: Indoleamine 2,3-dioxygenase (IDO1) inhibition is a promising target as an Alzheimer's disease (AD) Disease-modifying therapy capable of downregulating immunopathic neuroinflammatory processes. METHODS: To aid in the development of IDO inhibitors as potential AD therapeutics, we optimized a lipopolysaccharide (LPS) based mouse model of brain IDO1 inhibition by examining the dosedependent and time-course of the brain kynurenine:tryptophan (K:T) ratio to LPS via intraperitoneal dosing. RESULTS: We determined the optimal LPS dose to increase IDO1 activity in the brain, and the ideal time point to quantify the brain K:T ratio after LPS administration. We then used a brain penetrant tool compound, EOS200271, to validate the model, determine the optimal dosing profile and found that a complete rescue of the K:T ratio was possible with the tool compound. CONCLUSION: This LPS-based model of IDO1 target engagement is a useful tool that can be used in the development of brain penetrant IDO1 inhibitors for AD. A limitation of the present study is the lack of quantification of potential clinically relevant biomarkers in this model, which could be addressed in future studies.

The incidence and risk factors for venous thromboembolic events in patients with psoriasis and psoriatic arthritis.

OBJECTIVES: The risk of arterial vascular events is increased in patients with psoriatic disease (PsD), however, limited information exists about the risk of venous thromboembolism (VTE) in these patients. We assessed the incidence and risk factors for VTE in patients with PsD. METHODS: A multicentre cohort study was conducted involving patients with PsD followed prospectively from 1994 to 2020. Information about VTE, including pulmonary embolism (PE) and deep venous thrombosis (DVT), was obtained from provincial hospitalization databases. The incidence rate and cumulative probability of developing VTE were computed. Cox proportional hazards models were used to assess the association between risk factors, including comorbidities and disease-related factors, and the first VTE. RESULTS: A total 2,433 patients with PsD were analysed with 26 incident VTE (7 DVT alone, 12 PE alone, and 7 both PE and DVT). The incidence rates of the first VTE, DVT, and PE were 12, 6.5, and 8.8 events per 10,000 patient-years, respectively. The cumulative proportion of individuals developing VTE was 4.6% by 80 years of age. Independent predictors for VTE included older age, diabetes mellitus, and corticosteroid usage (all p<0.05). CONCLUSION: Older patients with PsD, those with diabetes, and those using corticosteroids are at a higher risk of developing VTE. Risk stratification of patients with these identified risk factors for VTE will allow for more individualized patient management and improved medication selection.

Immunomodulation and Disease Tolerance to Staphylococcus aureus.

The Gram-positive bacterium Staphylococcus aureus is one of the most frequent pathogens that causes severe morbidity and mortality throughout the world. S. aureus can infect skin and soft tissues or become invasive leading to diseases such as pneumonia, endocarditis, sepsis or toxic shock syndrome. In contrast, S. aureus is also a common commensal microbe and is often part of the human nasal microbiome without causing any apparent disease. In this review, we explore the immunomodulation and disease tolerance mechanisms that promote commensalism to S. aureus.