Zinc Oxide nanoparticles induce oxidative and proteotoxic stress in ovarian cancer cells and trigger apoptosis Independent of p53-mutation status

Ovarian cancer continues to be the most lethal among gynecological malignancies and the major cause for cancer-associated mortality among women. Limitations of current ovarian cancer therapeutics is highlighted by the high frequency of drug-resistant recurrent tumors and the extremely poor 5-year survival rates. Zinc oxide nanoparticles (ZnO-NPs) have shown promise in various biomedical applications including utility as anti-cancer agents. Here, we describe the synthesis and characterization of physical properties of ZnO-NPs of increasing particle size (15 nm - 55 nm) and evaluate their benefits as an ovarian cancer therapeutic using established human ovarian cancer cell lines. Our results demonstrate that the ZnO-NPs induce acute oxidative and proteotoxic stress in ovarian cancer cells leading to their death via apoptosis. The cytotoxic effect of the ZnO-NPs was found to increase slightly with a decrease in nanoparticle size. While ZnO-NPs caused depletion of both wild-type and gain-of-function (GOF) mutant p53 protein in ovarian cancer cells, their ability to induce apoptosis was found to be independent of the p53-mutation status in these cells. Taken together, these results highlight the potential of ZnO-NPs to serve as an anti-cancer therapeutic agent for treating ovarian cancers independent of the p53 mutants of the cancer cells.

Eicosanoid lipidome activation in post-mortem brain tissues of individuals with APOE4 and Alzheimer's dementia

BACKGROUND

Chronic neuroinflammation is one of the hallmarks of late-onset Alzheimer's disease (AD) dementia pathogenesis. Carrying the apolipoprotein ε4 (APOE4) allele has been associated with an accentuated response to brain inflammation and increases the risk of AD dementia progression. Among inflammation signaling pathways, aberrant eicosanoid activation plays a prominent role in neurodegeneration.

METHODS

Using brains from the Religious Order Study (ROS), this study compared measures of brain eicosanoid lipidome in older persons with AD dementia to age-matched controls with no cognitive impairment (NCI), stratified by APOE genotype.

RESULTS

Lipidomic analysis of the dorsolateral prefrontal cortex demonstrated lower levels of omega-3 fatty acids eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and DHA-derived neuroprotectin D1 (NPD-1) in persons with AD dementia, all of which associated with lower measures of cognitive function. A significant interaction was observed between carrying the APOE4 allele and higher levels of both pro-inflammatory lipids and pro-resolving eicosanoid lipids on measures of cognitive performance and on neuritic plaque burden. Furthermore, analysis of lipid metabolism pathways implicated activation of calcium-dependent phospholipase A2 (cPLA2), 5-lipoxygenase (5-LOX), and soluble epoxide hydrolase (sEH) enzymes.

CONCLUSION

These findings implicate activation of the eicosanoid lipidome in the chronic unresolved state of inflammation in AD dementia, which is increased in carriers of the APOE4 allele, and identify potential therapeutic targets for resolving this chronic inflammatory state.

Lipids and brain inflammation in APOE4-associated dementia

PURPOSE OF REVIEW

To highlight recent developments in studying mechanisms by which the apolipoprotein E4 (APOE4) allele affects the metabolism of brain lipids and predisposes the brain to inflammation and Alzheimer's disease (AD) dementia.

RECENT FINDINGS

APOE4 activates Ca2+ dependent phospholipase A2 (cPLA2) leading to changes in arachidonic acid (AA), eicosapentaenoic acid and docosahexaenoic acid signaling cascades in the brain. Among these changes, the increased conversion of AA to eicosanoids associates with sustained and unresolved chronic brain inflammation. The effects of APOE4 on the brain differ by age, disease stage, nutritional status and can be uncovered by brain imaging studies of brain fatty acid uptake. Reducing cPLA2 expression in the dementia brain presents a viable strategy that awaits to be tested.

SUMMARY

Fatty acid brain imaging techniques can clarify how changes to brain polyunsaturated fatty acid metabolism during the various phases of AD and guide the development of small molecules to mitigate brain inflammation.

NAP1051, a Lipoxin A4 Biomimetic Analogue, Demonstrates Antitumor Activity Against the Tumor Microenvironment

Resolving tumor-associated inflammation in the tumor microenvironment (TME) may promote antitumor effects. Lipoxin A4 (LXA4) is a short-lived endogenous bioactive lipid with potent anti-inflammatory and pro-resolving properties. Here, a biomimetic of LXA4, NAP1051, was shown to have LXA4-like in vitro properties and antitumor activity in colorectal cancer xenograft models. NAP1051 inhibited neutrophil chemotaxis toward fMLP and dose-dependently promoted dTHP-1 efferocytosis which was equipotent to aspirin-triggered lipoxin A4 (ATLA). In dTHP-1 cells, NAP1051 induced strong phosphorylation on ERK1/2 and AKT similar to formyl peptide receptor 2 (FPR2/ALX) agonists. In two mouse xenograft colorectal cancer models, NAP1051 significantly inhibited tumor growth when given orally at 4.8 to 5 mg/kg/day. Flow cytometric analyses showed that NAP1051 reduced splenic and intratumoral neutrophil and myeloid-derived suppressor cell populations, which correlated to the antitumor effect. In addition, NAP1051 reduced NETosis in the TME while stimulating T-cell recruitment. Overall, these results show that NAP1051 possesses key lipoxin-like properties and has antitumor activity against colorectal cancer via modulation of neutrophils and NETosis in the TME.

Eicosanoids and other oxylipins in liver injury, inflammation and liver cancer development

Liver cancer is a malignancy developed from underlying liver disease that encompasses liver injury and metabolic disorders. The progression from these underlying liver disease to cancer is accompanied by chronic inflammatory conditions in which liver macrophages play important roles in orchestrating the inflammatory response. During this process, bioactive lipids produced by hepatocytes and macrophages mediate the inflammatory responses by acting as pro-inflammatory factors, as well as, playing roles in the resolution of inflammation conditions. Here, we review the literature discussing the roles of bioactive lipids in acute and chronic hepatic inflammation and progression to cancer.

Abstract 1436: Mechanistic investigation of NAP1051, a lipoxin A4 biomimetic, in treating colorectal cancer

Purpose: Resolving tumor-associated inflammation in the tumor microenvironment (TME) can restore the immune response against malignant tissue. Lipoxin A4 (LXA4) is a short-lived endogenous bioactive lipid with potent anti-inflammatory and pro-resolving properties. We developed a LXA4 biomimetic, NAP1051, with increased stability and longer half-life, and demonstrated its properties using in vitro assays and in vivo xenograft tumor models and explored the underlying mechanism of action (MoA).

Methods: Differentiated HL-60 and THP-1 induced by DMSO and PMA, respectively, were used as models. dHL-60 was used to determine the effect of NAP1051 on fMLP-induced neutrophil chemotaxis. NAP1051-induced dTHP-1 efferocytosis of apoptotic dHL-60 was measured using fluorescent microscopy. Concentration escalation and time of NAP1051 exposure were used to probe the molecular mechanism using Western Blot and RT-PCR. The efficacy of oral NAP1051 was evaluated in CT26 (CRC) xenograft model established in immunocompetent Balb/c mice with a dosage escalation design.

Results: NAP1051 inhibited neutrophil chemotaxis towards fMLP by > 40% at 1, 10 and 100 nM (p < 0.05). NAP1051 dose-dependently promoted dTHP-1 efferocytosis (p < 0.05) and was equipotent to ATLA4. In dTHP-1 cells, NAP1051 induced strong phosphorylation on ERK1/2 and AKT from 10 nM to 1 µM. When compared to ATLA4 and W-peptide, NAP1051 caused strong phosphorylation at both S473 and T308 of AKT. The NAP1051-induced p-ERK1/2 and p-AKT were in parallel and in a dose-dependent and time-dependent way. MoA studies revealed that such p-ERK1/2 was mediated by MEK1/2. However, NAP1051 led to p-AKT at both S473 and T308 despite PI3K inhibition, indicating a PI3K-independent pathway was involved. In the mouse xenograft CRC model, we demonstrated that NAP1051 significantly inhibit tumor growth when given p.o. at 5 mg/kg/day. Flow cytometry on splenic cells showed that NAP1051 reduced splenic neutrophil and MDSC populations, which correlated to the tumor sizes. IHC analyses revealed that NAP1051 decreased the intratumoral Ly6G+ neutrophils most significantly at 5 mg/kg/day (p<0.1). In combination with low-dose 5-FU and CTX, NAP1051 significantly decreased splenic neutrophils and MDSCs compared to chemotherapies alone (p<0.05).

Conclusions: NAP1051 has LXA4-like activity including inhibiting fMLP-mediated neutrophil chemotaxis and promoting macrophage efferocytosis of apoptotic cells. The molecular MoA of NAP1051 involves ERK1/2 and AKT signaling pathways which are interrelated closely. A PI3K-independent pathway may be activated and resulted in AKT activation. NAP1051 inhibited tumor growth significantly at 5 mg/kg/day in a CRC model with significant changes in splenic and intratumoral immune cell populations. With these properties, NAP1051 may be an effective component in the treatment of CRCs by modulating the inflammatory immune cells in the TME.

Citation Format: Tiange Dong, Priyal Dave, Brandon Ebright, Kabir Ahluwalia, Eugene Zhou, Isaac Asante, Malika Salimova, Hua Pei, Tracey Lin, Andrew Mead, Zeyang Li, Nicos Petasis, Stan Louie. Mechanistic investigation of NAP1051, a lipoxin A4 biomimetic, in treating colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1436.

Transcorneal electrical stimulation restores DNA methylation changes in retinal degeneration

Background

Retinal degeneration is a major cause of irreversible blindness. Stimulation with controlled low-level electrical fields, such as transcorneal electrical stimulation (TES), has recently been postulated as a therapeutic strategy. With promising results, there is a need for detailed molecular characterization of the therapeutic effects of TES.

Methods

Controlled, non-invasive TES was delivered using a custom contact lens electrode to the retinas of Royal College of Surgeons (RCS) rats, a model of retinal degeneration. DNA methylation in the retina, brain and cell-free DNA in plasma was assessed by reduced representation bisulfite sequencing (RRBS) and gene expression by RNA sequencing.

Results

TES induced DNA methylation and gene expression changes implicated in neuroprotection in the retina of RCS rats. We devised an epigenomic-based retinal health score, derived from DNA methylation changes observed with disease progression in RCS rats, and showed that TES improved the epigenomic health of the retina. TES also induced DNA methylation changes in the superior colliculus: the brain which is involved in integrating visual signaling. Lastly, we demonstrated that TES-induced retinal DNA methylation changes were detectable in cell-free DNA derived from plasma.

Conclusion

TES induced DNA methylation changes with therapeutic effects, which can be measured in circulation. Based on these changes, we were able to devise a liquid biopsy biomarker for retinal health. These findings shed light on the therapeutic potential and molecular underpinnings of TES, and provide a foundation for the further development of TES to improve the retinal health of patients with degenerative eye diseases.

Effects of APOE4 on omega-3 brain metabolism across the lifespan

Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA), have important roles in human nutrition and brain health by promoting neuronal functions, maintaining inflammatory homeostasis, and providing structural integrity. As Alzheimer's disease (AD) pathology progresses, DHA metabolism in the brain becomes dysregulated, the timing and extent of which may be influenced by the apolipoprotein E ε4 (APOE4) allele. Here, we discuss how maintaining adequate DHA intake early in life may slow the progression to AD dementia in cognitively normal individuals with APOE4, how recent advances in DHA brain imaging could offer insights leading to more personalized preventive strategies, and how alternative strategies targeting PUFA metabolism pathways may be more effective in mitigating disease progression in patients with existing AD dementia.

Effects of age on lacrimal gland bioactive lipids

PURPOSE

Polyunsaturated fatty acids (PUFA) are a source of bioactive lipids regulating inflammation and its resolution.

METHODS

Changes in PUFA metabolism were compared between lacrimal glands (LGs) from young and aged C57BL/6 J mice using a targeted lipidomics assay, as was the gene expression of enzymes involved in the metabolism of these lipids.

RESULTS

Global reduction in PUFAs and their metabolites was observed in aged LGs compared to young controls, averaging between 25 and 66 % across all analytes. ꞷ-6 arachidonic acid (AA) metabolites were all reduced in aged LGs, where the changes in prostaglandin E2 (PGE2) and lipoxin A4 (LXA4) were statistically significant. Several other 5-lipoxygenase (5-LOX) mediated metabolites were significantly reduced in the aged LGs, including D-series resolvins (e.g., RvD4, RvD5, and RvD6). Along with the RvDs, several ꞷ-3 docosahexaenoic acid (DHA) metabolites such as 14-HDHA, neuroprotectin D1 (NPD1), Maresin 2 (MaR2), and MaR 1 metabolite (22-COOH-MaR1) were significantly reduced in aged LGs. Similarly, ꞷ-3 eicosapentaenoic acid (EPA) and its metabolites were significantly reduced in aged LGs, where the most significantly reduced was 18-HEPE. Using metabolite ratios (product:precursor) for specific metabolic conversions as surrogate enzymatic measures, reduced 12-LOX activity was identified in aged LGs.

CONCLUSION

In this study, global reduction of PUFAs and their metabolites was found in the LGs of aged female C57BL/6 J compared to young controls. A consistent reduction was observed across all detected lipid analytes except for ꞷ-3 docosapentaenoic acid (DPA) and its special pro-resolving mediator (SPM) metabolites in aged mice, suggesting an increased risk for LG inflammation.

Loss of 15-Lipoxygenase in Retinodegenerative RCS Rats

Retinitis pigmentosa (RP) is a retinal degenerative disease associated with a diversity of genetic mutations. In a natural progression study (NPS) evaluating the molecular changes in Royal College of Surgeons (RCS) rats using lipidomic profiling, RNA sequencing, and gene expression analyses, changes associated with retinal degeneration from p21 to p60 were evaluated, where reductions in retinal ALOX15 expression corresponded with disease progression. This important enzyme catalyzes the formation of specialized pro-resolving mediators (SPMs) such as lipoxins (LXs), resolvins (RvDs), and docosapentaenoic acid resolvins (DPA RvDs), where reduced ALOX15 corresponded with reduced SPMs. Retinal DPA RvD2 levels were found to correlate with retinal structural and functional decline. Retinal RNA sequencing comparing p21 with p60 showed an upregulation of microglial inflammatory pathways accompanied by impaired damage-associated molecular pattern (DAMP) clearance pathways. This analysis suggests that ALXR/FPR2 activation can ameliorate disease progression, which was supported by treatment with an LXA4 analog, NAP1051, which was able to promote the upregulation of ALOX12 and ALOX15. This study showed that retinal inflammation from activated microglia and dysregulation of lipid metabolism were central to the pathogenesis of retinal degeneration in RP, where ALXR/FPR2 activation was able to preserve retinal structure and function.

Basic Science and Pathogenesis

BACKGROUND

Synaptic loss predicts cognitive decline in Alzheimer's disease (AD). However, the critical disease modifying molecular mechanisms of synaptic failure remain elusive. Animal studies implicate the increased activation of cytosolic phospholipase (cPLA2) activation in synaptic loss and neuroinflammation. cPLA2 activation in human brain synapses have not yet been demonstrated. cPLA2 preferentially catalyzes the conversion of arachidonic acid (AA) to generate eicosanoids: lipid mediators of inflammation. Synaptosomes represent an excellent ex vivo model to study synaptic function in humans. Both PSD-95 and CamKII are synaptic markers that play essential role in learning and memory. In this study, we sought to determine whether cPLA2β is associated with synaptic markers, AD pathology and cognition in synaptosomes derived from human brain tissues.

METHOD

cPLA2β expression was analyzed in synaptosomes isolated from midfrontal cortex of postmortem brains in participants with no cognitive impairment (NCI, n = 20), mild cognitive impairment (MCI, n = 14) and AD (n = 19) from the clinically and pathologically well-characterized Religious Orders Study (ROS). Experimental methods included Western blotting, immunofluorescence staining, and liquid chromatography-tandem mass spectrometry to measure AA and its metabolites.

RESULT

cPLA2β was increased in synaptosomes/synapses of both MCI (*p < 0.05) and AD (***p < 0.001) compared to NCI. cPLA2β was inversely corelated with global cognitive function (r = -0.3667, **p < 0.01), and positively correlated with neurofibrillary tangles (r = 0.2877, *p < 0.05). Interestingly, cPLA2β was highly positively correlated with postsynaptic proteins of PSD-95 (r = 0.7901, ****p < 0.0001) and calcium/calmodulin dependent protein kinase II (CaMKII, r = 0.2825, *p<0.05). Immunofluorescence staining revealed the colocalization of cPLA2β with phospho-tau (AT8), synaptic PSD-95 and CaMKII in both AD and NCI brains. cPLA2β stained degenerative excitatory neurons. On a functional level, cPLA2b was positively correlated with AA (r = 0.5203, *p = 0.01) and its inflammatory metabolites of PGD2 (r = 0.496, *p<0.05) and PGE2 (r = 0.4623, *p<0.05).

CONCLUSION

This is the first report revealing increased expression of cPLA2β in synaptosomes from brains with MCI and AD compared with controls. cPLA2β is associated with tau pathology, AA and its metabolites, synaptic and cognitive performance. Whether reducing cPLA2b reverses AD pathology merits further investigation.

Basic Science and Pathogenesis

BACKGROUND

Cellular senescence is a hallmark of aging and has been implicated in several neurodegenerative diseases including Alzheimer's disease (AD). Senescence cells undergo changes in gene expression and metabolism and can exhibit a so-called "senescence-associated secretory phenotype" (SASP) characterized by increased secretion of pro-inflammatory molecules and factors which can damage nearby cells, contributing to AD pathology progression.

METHOD

In this study, we determined mechanisms of cellular senescence using human postmortem brain samples, cellular models, and APOE4 animal models. Bulk (n = 632) and single-cell nuclei transcriptomic profiling (n = 427) of the human dorsolateral prefrontal cortex (DLPFC) from the Religious Order Study/Memory Aging Project (ROSMAP). Lipidomic profiling was performed on a subset of 200 brains from the midfrontal cortex of ROS.

RESULT

Our findings revealed upregulation of cellular senescence signatures in postmortem AD brain tissues across different cell types in comparison with controls. We identified a strong correlation between SASP and arachidonic acid (AA) metabolism (P<0.001) in bulk RNA. In single cell nuclei transcriptomics, AA Activation was strongly correlated with P2RY12 (homeostatic) microglia (P<0.0001), and was associated with worse performance on all cognitive domains (p<0.001) and AD neuropathology (P<0.001) as shown in the figure. Lipidomic analysis of postmortem brain tissues confirmed activation of AA derived eicosanoids. Pathway analysis implicated the activation of calcium dependent phospholipase A2 (cPLA2). Inhibiting cPLA2 by treatment with ASB14780 reduced senescence-associated eicosanoids in APOE4 mouse models.

CONCLUSION

This work implicates the sustained activation of homeostatic microglia as an underlying mechanism of cellular senescence in the AD brain.

Hydroxypropyl-Beta Cyclodextrin Barrier Prevents Respiratory Viral Infections: A Preclinical Study

The emergence and mutation of pathogenic viruses have been occurring at an unprecedented rate in recent decades. The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has developed into a global public health crisis due to extensive viral transmission. In situ RNA mapping has revealed angiotensin-converting enzyme 2 (ACE2) expression to be highest in the nose and lower in the lung, pointing to nasal susceptibility as a predominant route for infection and the cause of subsequent pulmonary effects. By blocking viral attachment and entry at the nasal airway using a cyclodextrin-based formulation, a preventative therapy can be developed to reduce viral infection at the site of entry. Here, we assess the safety and antiviral efficacy of cyclodextrin-based formulations. From these studies, hydroxypropyl beta-cyclodextrin (HPBCD) and hydroxypropyl gamma-cyclodextrin (HPGCD) were then further evaluated for antiviral effects using SARS-CoV-2 pseudotypes. Efficacy findings were confirmed with SARS-CoV-2 Delta variant infection of Calu-3 cells and using a K18-hACE2 murine model. Intranasal pre-treatment with HPBCD-based formulations reduced viral load and inflammatory signaling in the lung. In vitro efficacy studies were further conducted using lentiviruses, murine hepatitis virus (MHV), and influenza A virus subtype H1N1. These findings suggest HPBCD may be used as an agnostic barrier against transmissible pathogens, including but not limited to SARS-CoV-2.

Synthesis and Preclinical Evaluation of 22-[18F]Fluorodocosahexaenoic Acid as a Positron Emission Tomography Probe for Monitoring Brain Docosahexaenoic Acid Uptake Kinetics

Docosahexaenoic acid [22:6(n-3), DHA], a polyunsaturated fatty acid, has an important role in regulating neuronal functions and in normal brain development. Dysregulated brain DHA uptake and metabolism are found in individuals carrying the APOE4 allele, which increases the genetic risk for Alzheimer's disease (AD), and are implicated in the progression of several neurodegenerative disorders. However, there are limited tools to assess brain DHA kinetics in vivo that can be translated to humans. Here, we report the synthesis of an ω-radiofluorinated PET probe of DHA, 22-[18F]fluorodocosahexaenoic acid (22-[18F]FDHA), for imaging the uptake of DHA into the brain. Using the nonradiolabeled 22-FDHA, we confirmed that fluorination of DHA at the ω-position does not significantly alter the anti-inflammatory effect of DHA in microglial cells. Through dynamic PET-MR studies using mice, we observed the accumulation of 22-[18F]FDHA in the brain over time and estimated DHA's incorporation coefficient (K*) using an image-derived input function. Finally, DHA brain K* was validated using intravenous administration of 15 mg/kg arecoline, a natural product known to increase the DHA K* in rodents. 22-[18F]FDHA is a promising PET probe that can reveal altered lipid metabolism in APOE4 carriers, AD, and other neurologic disorders. This new probe, once translated into humans, would enable noninvasive and longitudinal studies of brain DHA dynamics by guiding both pharmacological and nonpharmacological interventions for neurodegenerative diseases.