CPT1A-mediated fatty acid oxidation confers cancer cell resistance to immune-mediated cytolytic killing.

Although tumor-intrinsic fatty acid ß-oxidation (FAO) is implicated in multiple aspects of tumorigenesis and progression, the impact of this metabolic pathway on cancer cell susceptibility to immunotherapy remains unknown. Here, we report that cytotoxicity of killer T cells induces activation of FAO and upregulation of carnitine palmitoyltransferase 1A (CPT1A), the rate-limiting enzyme of FAO in cancer cells. The repression of CPT1A activity or expression renders cancer cells more susceptible to destruction by cytotoxic T lymphocytes. Our mechanistic studies reveal that FAO deficiency abrogates the prosurvival signaling in cancer cells under immune cytolytic stress. Furthermore, we identify T cell-derived IFN-γ as a major factor responsible for induction of CPT1A and FAO in an AMPK-dependent manner, indicating a dynamic interplay between immune effector cells and tumor targets. While cancer growth in the absence of CPT1A remains largely unaffected, established tumors upon FAO inhibition become significantly more responsive to cellular immunotherapies including chimeric antigen receptor-engineered human T cells. Together, these findings uncover a mode of cancer resistance and immune editing that can facilitate immune escape and limit the benefits of immunotherapies.

The NLRP3 Inflammasome Pathway: A Review of Mechanisms and Inhibitors for the Treatment of Inflammatory Diseases.

The NLRP3 inflammasome is a multiprotein complex that plays a pivotal role in regulating the innate immune system and inflammatory signaling. Upon activation by PAMPs and DAMPs, NLRP3 oligomerizes and activates caspase-1 which initiates the processing and release of pro-inflammatory cytokines IL-1ß and IL-18. NLRP3 is the most extensively studied inflammasome to date due to its array of activators and aberrant activation in several inflammatory diseases. Studies using small molecules and biologics targeting the NLRP3 inflammasome pathway have shown positive outcomes in treating various disease pathologies by blocking chronic inflammation. In this review, we discuss the recent advances in understanding the NLRP3 mechanism, its role in disease pathology, and provide a broad review of therapeutics discovered to target the NLRP3 pathway and their challenges.

Development of sulfonamide-based NLRP3 inhibitors: Further modifications and optimization through structure-activity relationship studies.

NLRP3 inflammasome dysregulation has been observed in many human diseases including neurodegenerative disorders. Thus, development of small molecule inhibitors targeting this protein complex represents a promising strategy to achieve disease intervention. In our continuing efforts to develop NLRP3 inhibitors, a recently identified lead inhibitor, YQ128, was further modified and optimized. The structure-activity relationship studies of this lead compound suggested its flexibility for structural modifications while the sulfonamide and benzyl moiety demonstrated being important for selectivity. Additionally, the systematic SAR studies also provided insights for designing NLRC4 and AIM2 inflammasome inhibitors. A new lead inhibitor, 19, was identified with improved potency (IC50: 0.12 ± 0.01 µM) and binding affinity (KD: 84 nM). Further characterization of this lead compound using wild type and nlrp3-/- mice confirmed its in vivo selective target engagement. PET studies using a radiotracer based on the structure of 19 also demonstrated its improved brain penetration compared to previous lead compounds. These results strongly encourage further testing of 19 in disease models.

A Novel Inhibitor Targeting NLRP3 Inflammasome Reduces Neuropathology and Improves Cognitive Function in Alzheimer's Disease Transgenic Mice.

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative disorder, and the most common type of dementia. A growing body of evidence has implicated neuroinflammation as an essential player in the etiology of AD. Inflammasomes are intracellular multiprotein complexes and essential components of innate immunity in response to pathogen- and danger-associated molecular patterns. Among the known inflammasomes, the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a critical role in the pathogenesis of AD. OBJECTIVE: We recently developed a novel class of small molecule inhibitors that selectively target the NLRP3 inflammasome. One of the lead compounds, JC124, has shown therapeutic efficacy in a transgenic animal model of AD. In this study we tested the preventative efficacy of JC124 in another strain of transgenic AD mice. METHODS: In this study, 5-month-old female APP/PS1 and matched wild type mice were treated orally with JC124 for 3 months. After completion of treatment, cognitive functions and AD pathologies, as well as protein expression levels of synaptic proteins, were assessed. RESULTS: We found that inhibition of NLRP3 inflammasome with JC124 significantly decreased multiple AD pathologies in APP/PS1 mice, including amyloid-ß (Aß) load, neuroinflammation, and neuronal cell cycle re-entry, accompanied by preserved synaptic plasticity with higher expression of pre- and post-synaptic proteins, increased hippocampal neurogenesis, and improved cognitive functions. CONCLUSION: Our study demonstrates the importance of the NLRP3 inflammasome in AD pathological development, and pharmacological inhibition of NLRP3 inflammasome with small molecule inhibitors represents a potential therapy for AD.

Discovery of carbon-11 labeled sulfonamide derivative: A PET tracer for imaging brain NLRP3 inflammasome.

We report herein the discovery of a positron emission tomography (PET) tracer for the (NOD)-like receptor protein 3 (NLRP3). Our recent medicinal chemistry campaign on developing sulfonamide-based NLRP3 inhibitors led to an analog, 1, with a methoxy substituent amenable to labeling with carbon-11. PET/CT imaging studies indicated that [11C]1 exhibited rapid blood-brain barrier (BBB) penetration and moderate brain uptake, as well as blockable uptake in the brain. [11C]1, thus suggesting the potential to serve as a useful tool for imaging NLRP3 inflammasome in living brains.

Discovery of Second-Generation NLRP3 Inflammasome Inhibitors: Design, Synthesis, and Biological Characterization.

NLRP3 inflammasomes have recently emerged as an attractive drug target for neurodegenerative disorders. In our continuing studies, a new chemical scaffold was designed as selective inhibitors of NLRP3 inflammasomes. Initial characterization of the lead HL16 demonstrated improved, however, nonselective inhibition on the NLRP3 inflammasome. Structure-activity relationship studies of HL16 identified a new lead, 17 (YQ128), with an IC50 of 0.30 ± 0.01 µM. Further studies from in vitro and in vivo models confirmed its selective inhibition on the NLRP3 inflammasome and its brain penetration. Furthermore, pharmacokinetic studies in rats at 20 mg/kg indicated extensive systemic clearance and tissue distribution, leading to a half-life of 6.6 h. However, the oral bioavailability is estimated to be only 10%, which may reflect limited GI permeability and possibly high first-pass effects. Collectively, these findings strongly encourage development of more potent analogues with improved pharmacokinetic properties from this new chemical scaffold.

Development of bivalent compounds as potential neuroprotectants for Alzheimer's disease.

In our efforts to further investigate the impact of the spacer and membrane anchor to the neuroprotective activities, a series of bivalent compounds that contain cholesterol and extended spacers were designed, synthesized and biologically characterized. Our results support previous studies that incorporation of a piperazine ring into the spacer significantly improved the protective potency of bivalent compounds in MC65 cell model. Spacer length beyond 21 atoms does not add further benefits with 21MO being the most potent one with an EC50 of 81.86 ±â€¯11.91 nM. Our results also demonstrated that bivalent compound 21MO suppressed the production of mitochondria reactive oxygen species. Furthermore, our results confirmed that both of the spacer and membrane anchor moiety are essential to metal binding. Collectively, the results provide further evidence and information to guide optimization of such bivalent compounds as potential neuroprotectants for Alzheimer's disease.