Lipoprotein-associated phospholipase A2 (Lp-PLA2) as a therapeutic target to prevent retinal vasopermeability during diabetes

Lipoprotein-associated phospholipase A2 (Lp-PLA2) hydrolyses oxidized low-density lipoproteins into proinflammatory products, which can have detrimental effects on vascular function. As a specific inhibitor of Lp-PLA2, darapladib has been shown to be protective against atherogenesis and vascular leakage in diabetic and hypercholesterolemic animal models. This study has investigated whether Lp-PLA2 and its major enzymatic product, lysophosphatidylcholine (LPC), are involved in blood-retinal barrier (BRB) damage during diabetic retinopathy. We assessed BRB protection in diabetic rats through use of species-specific analogs of darapladib. Systemic Lp-PLA2 inhibition using SB-435495 at 10 mg/kg (i.p.) effectively suppressed BRB breakdown in streptozotocin-diabetic Brown Norway rats. This inhibitory effect was comparable to intravitreal VEGF neutralization, and the protection against BRB dysfunction was additive when both targets were inhibited simultaneously. Mechanistic studies in primary brain and retinal microvascular endothelial cells, as well as occluded rat pial microvessels, showed that luminal but not abluminal LPC potently induced permeability, and that this required signaling by the VEGF receptor 2 (VEGFR2). Taken together, this study demonstrates that Lp-PLA2 inhibition can effectively prevent diabetes-mediated BRB dysfunction and that LPC impacts on the retinal vascular endothelium to induce vasopermeability via VEGFR2. Thus, Lp-PLA2 may be a useful therapeutic target for patients with diabetic macular edema (DME), perhaps in combination with currently administered anti-VEGF agents.

Polypharmacy and inappropriate medication use in patients with dementia: an underresearched problem

Multimorbidity and polypharmacy are increasingly prevalent across healthcare systems and settings as global demographic trends shift towards increased proportions of older people in populations. Numerous studies have demonstrated an association between polypharmacy and potentially inappropriate prescribing (PIP), and have reported high prevalence of PIP across settings of care in Europe and North America and, as a consequence, increased risk of adverse drug reactions, healthcare utilisation, morbidity and mortality. These studies have not focused specifically on people with dementia, despite the high risk of adverse drug reactions and PIP in this patient cohort. This narrative review considers the evidence currently available in the area, including studies examining prevalence of PIP in older people with dementia, how appropriateness of prescribing is assessed, the medications most commonly implicated, the clinical consequences, and research priorities to optimise prescribing for this vulnerable patient group. Although there has been considerable research effort to develop criteria to assess medication appropriateness in older people in recent years, the majority of tools do not focus on people with dementia. Of the limited number of tools available, most focus on the advanced stages of dementia in which life-expectancy is limited. The development of tools to assess medication appropriateness in people with mild-to-moderate dementia or across the full spectrum of disease severity represents an important gap in the research literature and is beginning to attract research interest, with recent studies considering the medication regimen as a whole, or misprescribing, overprescribing or underprescribing of certain medications/medication classes including anticholinergics, psychotropics, antibiotics and analgesics. Further work is required in development and validation of criteria to assess prescribing appropriateness in this vulnerable patient population, to determine prevalence of PIP in large cohorts of people with the full spectrum of dementia variants and severities and to examine the impact of PIP on health outcomes.