Would a Large tPA Trial for Those 4.5 to 6.0 Hours from Stroke Onset Be Good Value for Information?

Inducible Prostaglandin E Synthase as a Pharmacological Target for Ischemic Stroke

As the inducible terminal enzyme for prostaglandin E2 (PGE2) synthesis, microsomal PGE synthase-1 (mPGES-1) contributes to neuroinflammation and secondary brain injury after cerebral ischemia via producing excessive PGE2. However, a proof of concept that mPGES-1 is a therapeutic target for ischemic stroke has not been established by a pharmacological strategy mainly due to the lack of drug-like mPGES-1 inhibitors that can be used in relevant rodent models. To this end, we recently developed a series of novel small-molecule compounds that can inhibit both human and rodent mPGES-1. In this study, blockade of mPGES-1 by our several novel compounds abolished the lipopolysaccharide (LPS)-induced PGE2 and pro-inflammatory cytokines interleukin 1β (IL-1β), IL-6, and tumor necrosis factor α (TNF-α) in mouse primary brain microglia. Inhibition of mPGES-1 also decreased PGE2 produced by neuronal cells under oxygen-glucose deprivation (OGD) stress. Among the five enzymes for PGE2 biosynthesis, mPGES-1 was the most induced one in cerebral ischemic lesions. Systemic treatment with our lead compound MPO-0063 (5 or 10 mg/kg, i.p.) in mice after transient middle cerebral artery occlusion (MCAO) improved post-stroke well-being, decreased infarction and edema, suppressed induction of brain cytokines (IL-1β, IL-6, and TNF-α), alleviated locomotor dysfunction and anxiety-like behavior, and reduced the long-term cognitive impairments. The therapeutic effects of MPO-0063 in this proof-of-concept study provide the first pharmacological evidence that mPGES-1 represents a feasible target for delayed, adjunct treatment - along with reperfusion therapies - for acute brain ischemia.

Can Pay-for Performance Incentive Levels be Determined Using a Cost-Effectiveness Framework?

BACKGROUND

Healthcare payers in the United States are increasingly tying provider payments to quality and value using pay-for-performance policies. Cost-effectiveness analysis quantifies value in healthcare but is not currently used to design or prioritize pay-for-performance strategies or metrics. Acute ischemic stroke care provides a useful application to demonstrate how simulation modeling can be used to determine cost-effective levels of financial incentives used in pay-for-performance policies and associated challenges with this approach.

METHODS AND RESULTS

Our framework requires a simulation model that can estimate quality-adjusted life years and costs resulting from improvements in a quality metric. A monetary level of incentives can then be back-calculated using the lifetime discounted quality-adjusted life year (which includes effectiveness of quality improvement) and cost (which includes incentive payments and cost offsets from quality improvements) outputs from the model. We applied this framework to an acute ischemic stroke microsimulation model to calculate the difference in population-level net monetary benefit (willingness-to-pay of $50 000 to $150 000/quality-adjusted life year) accrued under current Medicare policy (stroke payment not adjusted for performance) compared with various hypothetical pay-for-performance policies. Performance measurement was based on time-to-thrombolytic treatment with tPA (tissue-type plasminogen activator). Compared with current payment, equivalent population-level net monetary benefit was achieved in pay-for-performance policies with 10-minute door-to-needle time reductions (5057 more acute ischemic stroke cases/y in the 0-3-hour window) incentivized by increasing tPA payment by as much as 18% to 44% depending on willingness-to-pay for health.

CONCLUSIONS

Cost-effectiveness modeling can be used to determine the upper bound of financial incentives used in pay-for-performance policies, although currently, this approach is limited due to data requirements and modeling assumptions. For tPA payments in acute ischemic stroke, our model-based results suggest financial incentives leading to a 10-minute decrease in door-to-needle time should be implemented but not exceed 18% to 44% of current tPA payment. In general, the optimal level of financial incentives will depend on willingness-to-pay for health and other modeling assumptions around parameter uncertainty and the relationship between quality improvements and long-run quality-adjusted life expectancy and costs.

Canonical Wnt Pathway Maintains Blood-Brain Barrier Integrity upon Ischemic Stroke and Its Activation Ameliorates Tissue Plasminogen Activator Therapy

Stroke induces blood-brain barrier (BBB) breakdown, which promotes complications like oedema and hemorrhagic transformation. Administration of recombinant tissue plasminogen activator (rtPA) within a therapeutic time window of 4.5 h after stroke onset constitutes the only existing treatment. Beyond this time window, rtPA worsens BBB breakdown. Canonical Wnt pathway induces BBB formation and maturation during ontogeny. We hypothesized that the pathway is required to maintain BBB functions after stroke; thus, its activation might improve rtPA therapy. Therefore, we first assessed pathway activity in the brain of mice subjected to transient middle cerebral artery occlusion (MCAo). Next, we evaluated the effect of pathway deactivation early after stroke onset on BBB functions. Finally, we assessed the impact of pathway activation on BBB breakdown associated to delayed administration of rtPA. Our results show that pathway activity is induced predominately in endothelial cells early after ischemic stroke. Early deactivation of the pathway using a potent inhibitor, XAV939, aggravates BBB breakdown and increases hemorrhagic transformation incidence. On the other hand, pathway activation using a potent activator, 6-bromoindirubin-3'-oxime (6-BIO), reduces the incidence of hemorrhagic transformation associated to delayed rtPA administration by attenuating BBB breakdown via promotion of tight junction formation and repressing endothelial basal permeability independently of rtPA proteolytic activity. BBB preservation upon pathway activation limited the deleterious effects of delayed rtPA administration. Our study demonstrates that activation of the canonical Wnt pathway constitutes a clinically relevant strategy to extend the therapeutic time window of rtPA by attenuating BBB breakdown via regulation of BBB-specific mechanisms.

MEPO promotes neurogenesis and angiogenesis but suppresses gliogenesis in mice with acute ischemic stroke

Previously study has proved the non-erythropoietic mutant erythropoietin (MEPO) exerted neuroprotective effects against ischemic cerebral injury, with an efficacy similar to that of wild-type EPO. This study investigates its effects on neurogenesis, angiogenesis, and gliogenesis in cerebral ischemic mice. Male C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO) and reperfusion. EPO (5000 U/kg), MEPO (5000 U/kg) or equal volume of normal saline was injected intraperitoneally. Neurological function was evaluated by Rota-rod test, Neurological severity scores (NSS) and Adhesive removal test. After ischemia and reperfusion (I/R), the survival rate, brain tissue loss, neurogenesis, angiogenesis and gliogenesis were detected by Nissl staining, Immunofluorescence and Western blot, respectively. The results shown that MEPO significantly increased survival rate, reduced brain tissue loss, and improved neurological function after MCAO (P < 0.05). Furthermore, MEPO obviously enhanced the proliferation of neuronal precursors (DCX) and promoted its differentiation into mature neurons (NeuN) (P < 0.05). In addition, compared to normal saline treatment mice, MEPO increased the number of BrdU-positive cells in the cerebral vasculature (P < 0.05). Whereas, MEPO treatment also reduced the numbers of newly generated astrocytes (GFAP) and microglia (Iba1) (P < 0.05). Among all the tests in this study, there was no significant difference between EPO group and MEPO group. Taken together, MEPO promoted the regeneration of neurons and blood vessels in peripheral area of infarction, and suppressed the gliogenesis, thus promoting neurogenesis, improving neurological function and survival rate. Our findings suggest that the MEPO may be a therapeutic drug for ischemic stroke intervention.