Our lab previously established that metformin, a first-line type two diabetes treatment, activates the Nrf2 pathway and improves post-stroke recovery. Metformin’s brain permeability value and potential interaction with blood–brain barrier (BBB) uptake and efflux transporters are currently unknown. Metformin has been shown to be a substrate of organic cationic transporters (Octs) in the liver and kidneys. Brain endothelial cells at the BBB have been shown to express Octs; thus, we hypothesize that metformin uses Octs for its transport across the BBB. We used a co-culture model of brain endothelial cells and primary astrocytes as an in vitro BBB model to conduct permeability studies during normoxia and hypoxia using oxygen–glucose deprivation (OGD) conditions. Metformin was quantified using a highly sensitive LC-MS/MS method. We further checked Octs protein expression using Western blot analysis. Lastly, we completed a plasma glycoprotein (P-GP) efflux assay. Our results showed that metformin is a highly permeable molecule, uses Oct1 for its transport, and does not interact with P-GP. During OGD, we found alterations in Oct1 expression and increased permeability for metformin. Additionally, we showed that selective transport is a key determinant of metformin’s permeability during OGD, thus, providing a novel target for improving ischemic drug delivery.

Despite the protective nature of the blood-brain barrier (BBB) and brain-protecting tissues, some types of CNS injury or stress can cause cerebral cytokine production and profound alterations in brain function. Neuroinflammation, which can also be accompanied by increased cerebral cytokine production, has a remarkable impact on the pathogenesis of many neurological illnesses, including loss of BBB integrity and ischemic stroke, yet effective treatment choices for these diseases are currently lacking. Although little is known about the brain effects of Metformin (MF), a commonly prescribed first-line antidiabetic drug, prior research suggested that it may be useful in preventing BBB deterioration and the increased risk of stroke caused by tobacco smoking (TS). Therefore, reducing neuroinflammation by escalating anti-inflammatory cytokine production and declining pro-inflammatory cytokine production could prove an effective therapeutic strategy for ischemic stroke. Hence, the current investigation was planned to explore the potential role of MF against stroke and TS-induced neuroinflammation and reactive oxygen species (ROS) production. Our studies revealed that MF suppressed releasing pro-inflammatory mediators like tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) by aiming at the nuclear factor kappa B (NF-κB) signaling pathway in primary neurons and astrocytes. MF also upregulated anti-inflammatory mediators, like interleukin-10 (IL-10), and interleukin-4 (IL-4), by upregulating the Nrf2-ARE signaling pathway. Adolescent mice receiving MF along with TS exposure also showed a notable decrease in NF-κB expression compared to the mice not treated with MF and significantly decreased the level of TNF-α, IL-1β, MCP-1, and MIP-2 and increased the levels of IL-10 and IL-4 through the activation of Nrf2-ARE signaling pathway. These results suggest that MF has anti-neuroinflammatory effects via inhibiting NF-κB signaling by activating Nrf2-ARE. These studies support that MF could be a strong candidate drug for treating and or preventing TS-induced neuroinflammation and ischemic stroke.

This review article explores the fundamental role of receptor targeting in overcoming drug resistance in cancer therapy, an area of critical concern given the persistently high rates of cancer morbidity and mortality globally. We highlight how receptor biology intersects with the development of therapeutic resistance with a specific focus on anti-angiogenic agents, immune checkpoint inhibitors, and monoclonal antibodies, which directly or indirectly influence receptor pathways. We also explore how other receptor tyrosine kinases can initially suppress tumor growth, yet often lead to resistance, underscoring the need for novel combinatorial approaches that incorporate advanced receptor modulation techniques. Further, the review delves into the mechanisms by which modulation of the tumor microenvironment and immune system via receptor pathways can overcome resistance to traditional immunotherapies. Additionally, emerging technologies in receptor-targeted nanomedicine are also highlighted, showcasing their potential to revolutionize drug delivery and improve therapeutic outcomes by targeting specific receptor interactions. Ultimately, this review calls for a deeper understanding of receptor dynamics to develop more precise interventions, including insights from various healthcare settings that can prevent or circumvent drug resistance, thus enhancing patient outcomes in oncology.

ID 53312 Poster Board 118 Neurolysin (Nln) is a peptidase that broadly distributes in the brain and functions to cleave various neuropeptides. Activation of Nln after ischemic stroke has been documented as a critical cerebroprotective mechanism and a promising pharmaceutical target for post-stroke treatment. Yet, drug development for stroke treatment remains challenging due to the additional protection afforded to the brain by the blood-brain barrier (BBB). Evaluation of BBB permeability and brain availability is an indispensable step for discovering new candidates for stroke treatment. Herein, we report a new class of Nln activators that show intriguing brain-drug-like properties. In vitro permeability assays suggest KS52 and KS73 out of this class compounds have significantly high BBB permeability (49.2-fold and 84.8-fold, p < 0.05 and p < 0.01, respectively) compared to the endogenous Nln activator histidine-tyrosine dipeptide (His-Tyr). Consistently, after a single dose of intravenous (i.v.) administration at 4 mg/kg, KS52 and KS73 rapidly enter healthy brains of mice, reach cerebral concentrations at 17.8 and 10.5 %injection dose/ml (%ID/ml) at 5 minutes, and maintain similar levels till 30 minutes. After 1 hour of post-administration, brain concentrations for the two compounds went down to 11.9 and 6.7 %ID/ml, respectively. It is worthy of note that, even at 4 hours the longest time point in this study, brain concentrations for KS52 and KS73 remain 7.9-fold and 13.0-fold higher than the A₅₀ (minimal concentration required for increasing 50% peptidase activity of Nln). Compared to KS73, KS52 show a comparable half-life (∼100 vs. ∼110 minutes) but a relatively higher uptake rate (∼ 50% more) in brains, which might be due to the slight difference between their chemical structures. Furthermore, brain availability of these compounds will also be tested in the ischemic brains of mice. Overall, the present study reports a new class of Nln activators with high BBB permeability, rapid brain uptake and optimal brain retention time, providing valuable pharmacokinetic evidence supporting the future development of these agents as promising candidates for post-stroke treatment. This project was supported by NIH grant R01NS106879 to P.C.T., V.T.K. and T.J.A.