Contrasting the neuroprotective and gliotoxic effects of PPARγ agonists

Functionalization of Tetrazoles Bearing the Electrochemically Cleavable 1N-(6-Methylpyridyl-2-methyl) Protecting Group

6-Methylpyridyl-2-methyl protected tetrazoles can be C-H deprotonated using the turbo-Grignard reagent and involved in the reactions with aldehydes and ketones. The protecting group can be cleaved under reductive electrochemical conditions using Pb bronze as a cathode and Zn as a sacrificial anode.

Computational Drug Repurposing for Alzheimer's Disease Using Risk Genes From GWAS and Single-Cell RNA Sequencing Studies

Background: Traditional therapeutics targeting Alzheimer's disease (AD)-related subpathologies have so far proved ineffective. Drug repurposing, a more effective strategy that aims to find new indications for existing drugs against other diseases, offers benefits in AD drug development. In this study, we aim to identify potential anti-AD agents through enrichment analysis of drug-induced transcriptional profiles of pathways based on AD-associated risk genes identified from genome-wide association analyses (GWAS) and single-cell transcriptomic studies. Methods: We systematically constructed four gene lists (972 risk genes) from GWAS and single-cell transcriptomic studies and performed functional and genes overlap analyses in Enrichr tool. We then used a comprehensive drug repurposing tool Gene2Drug by combining drug-induced transcriptional responses with the associated pathways to compute candidate drugs from each gene list. Prioritized potential candidates (eight drugs) were further assessed with literature review. Results: The genomic-based gene lists contain late-onset AD associated genes (BIN1, ABCA7, APOE, CLU, and PICALM) and clinical AD drug targets (TREM2, CD33, CHRNA2, PRSS8, ACE, TKT, APP, and GABRA1). Our analysis identified eight AD candidate drugs (ellipticine, alsterpaullone, tomelukast, ginkgolide A, chrysin, ouabain, sulindac sulfide and lorglumide), four of which (alsterpaullone, ginkgolide A, chrysin and ouabain) have shown repurposing potential for AD validated by their preclinical evidence and moderate toxicity profiles from literature. These support the value of pathway-based prioritization based on the disease risk genes from GWAS and scRNA-seq data analysis. Conclusion: Our analysis strategy identified some potential drug candidates for AD. Although the drugs still need further experimental validation, the approach may be applied to repurpose drugs for other neurological disorders using their genomic information identified from large-scale genomic studies.

Tumor Immune Microenvironment Related Gene-Based Model to Predict Prognosis and Response to Compounds in Ovarian Cancer

BACKGROUND

The tumor immune microenvironment (TIME) has been recognized to be an imperative factor facilitating the acquisition of many cancer-related hallmarks and is a critical target for targeted biological therapy. This research intended to construct a risk score model premised on TIME-associated genes for prediction of survival and identification of potential drugs for ovarian cancer (OC) patients.

METHODS AND RESULTS

The stromal and immune scores were computed utilizing the ESTIMATE algorithm in OC patient samples from The Cancer Genome Atlas (TCGA) database. Weighted gene co-expression network and differentially expressed genes analyses were utilized to detect stromal-and immune-related genes. The Least Absolute Shrinkage and Selection Operator (LASSO)-Cox regression was utilized for additional gene selection. The genes that were selected were utilized as the input for a stepwise regression to construct a TIME-related risk score (TIMErisk), which was then validated in Gene Expression Omnibus (GEO) database. For the evaluation of the protein expression levels of TIME regulators, the Human Protein Atlas (HPA) dataset was utilized, and for their biological functions, the TIMER and CIBERSORT algorithm, immunoreactivity, and Immune Cell Abundance Identifier (ImmuCellAI) were used. Possible OC medications were forecasted utilizing the Genomics of Drug Sensitivity in Cancer (GDSC) database and connectivity map (CMap). TIMErisk was developed based on ALPK2, CPA3, PTGER3, CTHRC1, PLA2G2D, CXCL11, and ZNF683. High TIMErisk was recognized as a poor factor for survival in the GEO and TCGA databases; subgroup analysis with FIGO stage, grade, lymphatic and venous invasion, debulking, and tumor site also indicated similar results. Functional immune cells corresponded to more incisive immune reactions, including secretion of chemokines and interleukins, natural killer cell cytotoxicity, TNF signaling pathway, and infiltration of activated NK cells, eosinophils, and neutrophils in patients with low TIMErisk. Several small molecular medications which may enhance the prognosis of patients in the TIMErisk subgroup were identified. Lastly, an enhanced predictive performance nomogram was constructed by compounding TIMErisk with the FIGO stage and debulking.

CONCLUSION

These findings may offer a valuable indicator for clinical stratification management and personalized therapeutic options for OC patients and may be a foundation for future mechanistic research of their association.

PPAR-gamma Thiazolidinedione Agonists and Immunotherapy in the Treatment of Brain Tumors

Thiazolidinediones (TZDs) are selective agonists of the peroxisome proliferator-activated receptor (PPAR) gamma, a transcription factor belonging to the superfamily of nuclear hormone receptors. Although activation of PPARγ by TZDs has been best characterized by its ability to regulate expression of genes associated with lipid metabolism, PPARγ agonists have other physiological effects including modulating pro- and anti-inflammatory gene expression and inducing apoptosis in several cell types including glioma cells and cell lines. Immunotherapeutic approaches to reducing brain tumors are focused on means to reduce the immunosuppressive responses of tumors which dampen the ability of cytotoxic T-lymphocytes to kill tumors. Initial studies from our lab show that combination of an immunotherapeutic strategy with TZD treatment provides synergistic benefit in animals with implanted tumors. The potential of this combined approach for treatment of brain tumors is reviewed in this report.

Insulin, insulin-like growth factors and incretins: neural homeostatic regulators and treatment opportunities

Mood disorders may be conceptualized as progressive neurodegenerative disorders associated with cognitive decline. Novel treatments capable of preserving and/or enhancing cognitive function represent an area of priority for research in the future. Insulin, insulin-like growth factor (IGF)-1 and incretins may play a critical role in both physiological and pathophysiological processes of the CNS. An emerging paradigm regarding the pathophysiology of mood disorders posits that alterations in biological networks that mediate stress compromise optimal neuronal and glial function. A growing body of evidence indicates that central administration of insulin may enhance cognitive function in both healthy and cognitively impaired individuals. The neuroactive peptides, insulin, IGF-1 and incretins, or agents that facilitate their central effects (e.g. insulin-sensitizing agents), may constitute novel and possibly disease-modifying neurocognitive treatments.

Thiazolidinediones: novel treatments for cognitive deficits in mood disorders?

The aim of this review is to provide a rationale for evaluating thiazolidinediones (TZDs) as putative treatments for cognitive deficits in individuals with mood disorders. A MedLine search of all English-language articles published between January 1966 and August 2006 was conducted. The search terms were: the non-proprietary names of TZDs (e.g., rosiglitazone and pioglitazone), peroxisome proliferator-activated receptor, cognition, neuroprotection, inflammation, oxidative stress, cellular metabolism and excitotoxicity cross-referenced with the individual names of mood (e.g., major depressive disorder and bipolar disorder) and dementing disorders (e.g., Alzheimer's disease) as defined in the Diagnostic and Statistical Manual of Mental Disorders third edition, revised/fourth edition, text revision (DSM-III-R/IV-TR). The search was augmented with a manual review of article reference lists. Articles selected for review were based on adequacy of sample size, the use of standardized experimental procedures, validated assessment measures and overall manuscript quality. Contemporary pathophysiologic models of mood disorders emphasize alterations in neuronal plasticity, metabolism and cytoarchitecture with associated regional abnormalities in neuronal (and glial) density and morphology. These abnormalities are hypothesized to subserve cognitive deficits and other clinical features of mood disorders. TZDs may attenuate, abrogate and/or reverse the neurotoxic effects of depressive illness by means of disparate mechanisms, notably insulin signaling, anti-inflammation, glucocorticoid activity and cellular metabolism. Extant data provide the basis for formulating a hypothesis that TZDs may be salutary for cognitive deficits and several aspects of somatic health (e.g., cardiovascular disease) associated with mood disorders.

Prolonged survival of mice with established intracerebral glioma receiving combined treatment with peroxisome proliferator-activated receptor-gamma thiazolidinedione agonists and interleukin-2-secreting syngeneic/allogeneic fibroblasts

OBJECT

In this study the authors explored the benefits of treating C57B1/6 mice with an established intracerebral glioma by combining immunotherapy with interleukin (IL)-2-secreting syngeneic/allogeneic fibroblasts administered into the tumor bed along with the chemotherapeutic agent pioglitazone, a thiazolidinedione (TZD). The TZDs are agonists of the peroxisome proliferator-activated receptor-gamma. They have been found to exert antiproliferative effects on several transformed cell lines. Data from prior studies by these authors have revealed the immunotherapeutic properties of the IL-2-secreting fibroblasts in treating intracerebral gliomas in mice.

METHODS

The sensitivity of GL261 glioma cells and primary astrocytes to pioglitazone was determined in vitro by incubating the cells with increasing amounts of the drug. Viability was assessed by measuring lactate dehydrogenase release, and effects on metabolism were determined by measuring superoxide production and levels of superoxide dismutase. The GL261 cells were injected intracerebrally into C57B1/6 mice, followed by treatment with pioglitazone either orally or intracerebrally into the tumor bed. The effect of the combined therapy was determined by injecting C57B1/6 mice with an established intracerebral GL261 glioma with IL-2-secreting allogeneic fibroblasts and pioglitazone directly into the tumor bed through a unique cannula system. Pioglitazone was found to induce cell death in GL261 glioma cells grown in vitro while causing only modest damage to astrocytes. The application of pioglitazone also resulted in a significantly greater induction of cellular superoxide in glioma cells than in astrocytes, which can activate apoptotic pathways. Pioglitazone administered intracerebrally (p < 0.05) but not orally was found to prolong survival in mice harboring an intracerebral glioma. Synergistic effects of combination therapy on prolonging survival were found in mice receiving both pioglitazone and IL-2-secreting fibroblasts (p < 0.005, compared with untreated animals). Pioglitazone induces metabolic and oxidative stresses that are tolerated by astrocytes but not glioma cells, which could account for selective vulnerability and increased sensitivity to IL-2, suggesting potential for the use of this Food and Drug Administration-approved drug in the treatment of brain tumors.

CONCLUSIONS

The data indicate the beneficial effects of combination therapy using pioglitazone and immunotherapy in mice harboring intracerebral glioma.

Thiazolidinediones: from antioxidant to neurotherapeutic?

A prevailing paradigm regarding the pathophysiology of mood disorders posits that these syndromes are possibly neurodegenerative. Alterations in interacting biological networks which subserve metabolism, inflammation, immune function, and stress response are hypothesized to mediate the neurotoxicity and allostasis associated with mood disorders. Preclinical evidence indicates that thiazolidinediones (TZDs) exert neurotherapeutic (e.g., neurotrophic) effects. Preliminary clinical evidence also suggests that TZDs may be salutary for mental disorders in which neurocognitive deficits are a central feature. We propose that TZDs constitute a potentially novel disease-modifying treatment avenue for mood disorders.

Differential effects of PPARγ agonists on the metabolic properties of gliomas and astrocytes

Recent studies show that thiazolinediones (TZDs), agonists of the peroxisome proliferator-activated receptor gamma (PPARgamma), induce apoptosis in glioma and glioblastoma cells. Here we compared the effects of troglitazone (Trog), a TZD with low affinity for binding to PPARgamma but with potent metabolic effects, on survival and metabolism in GL261 glioma cells versus primary astrocytes. Trog dose-dependently induced cell death in GL261 cells (with over 90% death at 30 microM) but did not cause any toxicity in astrocytes at the same doses. Measurements of glucose and lactate levels after incubation with Trog (30 microM) indicated an overall increase of glucose consumption and lactate production in both cell types. In astrocytes the ratio of lactate produced to glucose utilized was not significantly altered by Trog, while in glioma cells this ratio was decreased by about 40%. Trog dose-dependently reduced mitochondrial membrane potential (DeltaPsi(m)) in both cell types; and the loss of DeltaPsi(m) was greater in the tumor cells (90% loss at 20 microM) than in astrocytes (70% loss at 20 microM). These results suggest that differences in metabolic responses could contribute to the selective resistance of astrocytes to cytotoxic effects of Trog. TZDs such as Trog should therefore be considered for testing in treatment of gliomas.

Pioglitazone does not increase cerebral glucose utilisation in a murine model of Alzheimer's disease and decreases it in wild-type mice

AIMS/HYPOTHESIS

Clinical trials are in progress to test thiazolidinediones in neurodegenerative diseases such as Alzheimer's disease that involve deficiencies in brain glucose metabolism. While thiazolidinediones enhance glucose uptake in non-cerebral tissues, their impact on brain energy metabolism has not been investigated in vivo. We thus determined whether the thiazolidinedione pioglitazone reverses the decrease in cerebral glucose utilisation (CGU) in a model of brain metabolic deficiency related to Alzheimer's disease. Results are relevant to diabetes because millions of diabetic patients take pioglitazone as an insulin-sensitising drug, and diabetes increases the risk of developing Alzheimer's disease.

MATERIALS AND METHODS

The regional pattern of CGU was measured with the 2-deoxy [(14)C] glucose autoradiographic technique in adult awake mice overexpressing transforming growth factor beta1 (TGFbeta1), and in wild-type littermates. Mice were treated with pioglitazone for 2 months.

RESULTS

Measurement of CGU in 27 brain regions confirmed that TGFbeta1 overexpression induced hypometabolism across the brain. Pioglitazone did not reverse the effect of TGFbeta1 overexpression and decreased regional CGU in control animals by up to 23%. The extent of the regional CGU decrease induced by pioglitazone, but not that induced by TGFbeta1, correlated strongly with basal CGU, suggesting that the higher the local metabolic rate the greater the reduction of CGU effected by pioglitazone.

CONCLUSIONS/INTERPRETATION

In contrast to its stimulatory effect in non-cerebral tissues, chronic treatment with pioglitazone decreases CGU in vivo. This evidence does not support the hypothesis that pioglitazone could act as a metabolic enhancer in Alzheimer's disease, and raises the question of how thiazolidinediones could be beneficial in neurodegenerative diseases.

Peroxisome proliferator-activated receptor-gamma agonists inhibit the activation of microglia and astrocytes: implications for multiple sclerosis

Peroxisome proliferator-activated receptor (PPAR)-gamma agonists, including thiazolidinediones (TZDs) and 15-deoxy-Delta(12,14) prostaglandin J(2) (15d-PGJ(2)), have been shown to be effective in the treatment of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). This study aimed to compare the anti-inflammatory actions of three TZDs - rosiglitazone, pioglitazone, and ciglitazone - with those of 15d-PGJ(2) on stimulated mouse microglia and astrocytes. The results show that TZDs and 15d-PGJ(2) are effective in inhibiting production of nitric oxide, the pro-inflammatory cytokines TNF-alpha, IL-1beta, and IL-6, and the chemokine MCP-1 from microglia and astrocytes. However, 15d-PGJ(2) was a more potent suppressor of pro-inflammatory activity than the TZDs. These studies suggest that PPAR-gamma agonists modulate EAE, at least in part, by inhibiting the activation of microglia and astrocytes. The studies further suggest that PPAR-gamma agonists may be effective in the treatment of MS.