NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) is an intracellular sensor that detects a broad range of microbial motifs, endogenous danger signals and environmental irritants, resulting in the formation and activation of the NLRP3 inflammasome. Assembly of the NLRP3 inflammasome leads to caspase 1-dependent release of the pro-inflammatory cytokines IL-1β and IL-18, as well as to gasdermin D-mediated pyroptotic cell death. Recent studies have revealed new regulators of the NLRP3 inflammasome, including new interacting or regulatory proteins, metabolic pathways and a regulatory mitochondrial hub. In this Review, we present the molecular, cell biological and biochemical bases of NLRP3 activation and regulation and describe how this mechanistic understanding is leading to potential therapeutics that target the NLRP3 inflammasome.

The NLRP3 inflammasome: molecular activation and regulation to therapeutics

Danger signals are a hallmark of many common inflammatory diseases, and these stimuli can function to activate the cytosolic innate immune signalling receptor NLRP3 (NOD-, LRR- and pyrin domain-containing 3). Once activated, NLRP3 nucleates the assembly of an inflammasome, leading to caspase 1-mediated proteolytic activation of the interleukin-1β (IL-1β) family of cytokines, and induces an inflammatory, pyroptotic cell death. Pharmacological inhibition of NLRP3 activation results in potent therapeutic effects in a wide variety of rodent models of inflammatory diseases, effects that are mirrored by genetic ablation of NLRP3. Although these findings highlight the potential of NLRP3 as a drug target, an understanding of NLRP3 structure and activation mechanisms is incomplete, which has hampered the discovery and development of novel therapeutics against this target. Here, we review recent advances in our understanding of NLRP3 activation and regulation, highlight the evolving landscape of NLRP3 modulators and discuss opportunities for pharmacologically targeting NLRP3 with novel small molecules.

Targeting the NLRP3 inflammasome in inflammatory diseases

The NLRP3 inflammasome is a multimeric protein complex that initiates an inflammatory form of cell death and triggers the release of proinflammatory cytokines IL-1β and IL-18. The NLRP3 inflammasome has been implicated in a wide range of diseases, including Alzheimer’s disease, Prion diseases, type 2 diabetes, and some infectious diseases. It has been found that a variety of stimuli including danger-associated molecular patterns (DAMPs, such as silica and uric acid crystals) and pathogen-associated molecular patterns (PAMPs) can activate NLRP3 inflammasome, but the specific regulatory mechanisms of NLRP3 inflammasome activation remain unclear. Understanding the mechanisms of NLRP3 activation will enable the development of its specific inhibitors to treat NLRP3-related diseases. In this review, we summarize current understanding of the regulatory mechanisms of NLRP3 inflammasome activation as well as inhibitors that specifically and directly target NLRP3.

Recent advances in the mechanisms of NLRP3 inflammasome activation and its inhibitors.

Cannabis sativa L. is possibly one of the oldest plants cultivated by man, but has remained a source of controversy throughout its history. Whether pariah or panacea, this most versatile botanical has provided a mirror to medicine and has pointed the way in the last two decades toward a host of medical challenges from analgesia to weight loss through the discovery of its myriad biochemical attributes and the endocannabinoid system wherein many of its components operate. This study surveys the history of cannabis, its genetics and preparations. A review of cannabis usage in Ancient Egypt will serve as an archetype, while examining first mentions from various Old World cultures and their pertinence for contemporary scientific investigation. Cannabis historians of the past have provided promising clues to potential treatments for a wide array of currently puzzling medical syndromes including chronic pain, spasticity, cancer, seizure disorders, nausea, anorexia, and infectious disease that remain challenges for 21st century medicine. Information gleaned from the history of cannabis administration in its various forms may provide useful points of departure for research into novel delivery techniques and standardization of cannabis-based medicines that will allow their prescription for treatment of these intractable medical conditions.

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History of Cannabis and Its Preparations in Saga, Science, and Sobriquet

Neuroinflammation and neurodegeneration often result from the aberrant deposition of aggregated host proteins, including amyloid‐β, α‐synuclein, and prions, that can activate inflammasomes. Inflammasomes function as intracellular sensors of both microbial pathogens and foreign as well as host‐derived danger signals. Upon activation, they induce an innate immune response by secreting the inflammatory cytokines interleukin (IL)‐1β and IL‐18, and additionally by inducing pyroptosis, a lytic cell death mode that releases additional inflammatory mediators. Microglia are the prominent innate immune cells in the brain for inflammasome activation. However, additional CNS‐resident cell types including astrocytes and neurons, as well as infiltrating myeloid cells from the periphery, express and activate inflammasomes. In this review, we will discuss current understanding of the role of inflammasomes in common degenerative diseases of the brain and highlight inflammasome‐targeted strategies that may potentially treat these diseases.

https://www.embopress.org/doi/epdf/10.15252/emmm.201810248

Inflammasomes in neuroinflammatory and neurodegenerative diseases.

Activation of the NLRP3 inflammasome induces maturation of IL-1β and IL-18, both validated targets for treating acute and chronic inflammatory diseases. Here, we demonstrate that OLT1177, an orally active β-sulfonyl nitrile molecule, inhibits activation of the NLRP3 inflammasome. In vitro, nanomolar concentrations of OLT1177 reduced IL-1β and IL-18 release following canonical and noncanonical NLRP3 inflammasome activation. The molecule showed no effect on the NLRC4 and AIM2 inflammasomes, suggesting specificity for NLRP3. In LPS-stimulated human blood-derived macrophages, OLT1177 decreased IL-1β levels by 60% and IL-18 by 70% at concentrations 100-fold lower in vitro than plasma concentrations safely reached in humans. OLT1177 also reduced IL-1β release and caspase-1 activity in freshly obtained human blood neutrophils. In monocytes isolated from patients with cryopyrin-associated periodic syndrome (CAPS), OLT1177 inhibited LPS-induced IL-1β release by 84% and 36%. Immunoprecipitation and FRET analysis demonstrated that OLT1177 prevented NLRP3-ASC, as well as NLRP3-caspase-1 interaction, thus inhibiting NLRP3 inflammasome oligomerization. In a cell-free assay, OLT1177 reduced ATPase activity of recombinant NLRP3, suggesting direct targeting of NLRP3. Mechanistically, OLT1177 did not affect potassium efflux, gene expression, or synthesis of the IL-1β precursor. Steady-state levels of phosphorylated NF-κB and IkB kinase were significantly lowered in spleen cells from OLT1177-treated mice. We observed reduced IL-1β content in tissue homogenates, limited oxidative stress, and increased muscle oxidative metabolism in OLT1177-treated mice challenged with LPS. Healthy humans receiving 1,000 mg of OLT1177 daily for 8 d exhibited neither adverse effects nor biochemical or hematological changes.

OLT1177, a β-sulfonyl nitrile compound, safe in humans, inhibits the NLRP3 inflammasome and reverses the metabolic cost of inflammation.

Cannabis vaporization is a technology designed to deliver inhaled cannabinoids while avoiding the respiratory hazards of smoking by heating cannabis to a temperature where therapeutically active canna- binoid vapors are produced, but below the point of combustion where noxious pyrolytic byproducts are formed. This study was designed to evaluate the efficacy of an herbal vapor- izer known as the Volcano ® , produced by Storz & Bickel GmbH&Co. KG, Tuttlingen, Germany (http://www.storz-bickel.com). Three 200 mg samples of standard NIDA cannabis were vaporized at temperatures of 155°-218°C. For comparison, smoke from combusted samples was also tested.

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Cannabis Vaporizer Combines Efficient Delivery of THC with Effective Suppression of Pyrolytic Compounds

The present invention provides a novel approach for the preparation of fatty alcohol esters of α-hydroxy carboxylic acids. The present invention also provides a novel topical gel for the transdermal delivery of steroids using the fatty alcohol esters as permeation enhancers.

Synthesis of fatty alcohol esters of alpha-hydroxy carboxylic acids, the use of the same as percutaneous permeation enhancers, and topical gels for the transdermal delivery of steroids

The present invention is directed to a compound of 2-N halo-4-methylsulfonyl-butyric acid, such as 2-N chloro-4-methylsulfonyl-butyric acid, or a pharmaceutically acceptable salt or solvate thereof. The present invention is also directed to a pharmaceutical composition comprises the compound and a pharmaceutically acceptable carrier. The present invention is further directed to a method for treating inflammation or inflammatory-related disorders, bacterial infection, pain, or skin conditions, by administering 2-N halo-4-methylsulfonyl-butyric acid to a subject in need thereof.

Compounds for treating inflammation and pain

The present invention provides a novel approach for the preparation of fatty alcohol esters of α-hydroxy carboxylic acids. In one form of the invention, the target fatty alcohol ester of α-hydroxy carboxylic acid is produced by converting a lower alkyl ester of α-hydroxy carboxylic acid into a fatty alcohol ester of α-hydroxy carboxylic acid via alcoholysis (i.e., transesterification). The transesterification process is an equilibrium reaction, catalyzed chemically (i.e., with acids or bases) or enzymatically, that is shifted in the desired direction to produce the desired product. One preferred way of shifting the reaction in the direction of the desired product is by reducing the concentration of one of the products (e.g., distillation of a lower-boiling alcohol as soon as it is formed). Another preferred way of shifting the reaction in the direction of the desired product is by increasing the concentration of one of the reactants (e.g., adding more of the starting ester).

Joseph P. St. Laurent

Papers

OLT1177, a β-sulfonyl nitrile compound, safe in humans, inhibits the NLRP3 inflammasome and reverses the metabolic cost of inflammation.

Cannabis Vaporizer Combines Efficient Delivery of THC with Effective Suppression of Pyrolytic Compounds

Synthesis of fatty alcohol esters of alpha-hydroxy carboxylic acids, the use of the same as percutaneous permeation enhancers, and topical gels for the transdermal delivery of steroids

Compounds for treating inflammation and pain

Synthesis of fatty alcohol esters of alpha-hydroxy carboxylic acids and their use as percutaneous absorption enhancers