L9 Targeting NLRP3 Inflammasome Flashcards
__ tend to activate the inflammasome
DAMPs
The priming signal leads to…
increased transcription of NLRP3 gene (via NF-κβ activation)
Post-translational modifications that stabilise the inflammasome
Phosphorylation and ubiquitylation
NLRP3 inflammasome activation leads to release of which pro-inflammatory cytokines?
IL-1β and IL-18
NLRP3 contains an amino-terminal __ domain
pyrin
NLRP3 inflammasome components
- sensor molecule (NLRP3)
- adaptor molecule (ASC)
- effector molecule (caspase 1)
NLRP3 NACHT domain contains __ activity
ATPase
ASC proteolytically cleaves __ , which cleaves pro-IL-1β and pro-IL-18
caspase 1
NLRP3 binds to __ to secure structure and recruit ASC
NEK7
Inflammatory cell death
pyroptosis
Rate-limiting step in activating the inflammasome
The amount of NLRP3 expressed (abundance of NLRP3 gene)
Predominant function of a secondary signal
Help recruit ASC component and ultimately cleave procaspase 1
Most abundance and best described secondary signal
Efflux of K⁺ out of primed cell to activate NLRP3 inflammasome
Caspase 1 also cleaves __ , which inserts into the membrane and forms pores.
Gasdermin D (GSDMD)
__ position in LRR domain inhibits activation of NLRP3
Y861
Phosphorylation at S295 in NACHT domain by __ inhibits NLRP3
PKA (while PKD activates NLRP3)
__ at S198 in linker region between NACHT and pyrin domains inhibits NLRP3
Dephosphorylation
Unifying factor of NLRP3 activators
they all induce cellular stress, which is then sensed by NLRP3
Most common activating stimuli for NLRP3
- Potassium efflux
- Cathepsin release
- Mitochondrial dysfunction
- Metabolic changes
Examples of second signals
- K⁺ efflux and pore formation
- Lysosomal disruption
- Mitochondrial dysfunction
- Metabolic changes e.g. SCFAs
Saturated fatty acid, palmitate, __ NLRP3 priming
activates
SCFAs, butyrate and propionate, __ NLRP3 priming
inhibit
Example of a ketone body that inhibits NLRP3
β-hydroxybutyrate (BHB) (via inhibition of K⁺ efflux)
What is CAPS?
Cryopryin-associated periodic syndromes (caused by gain-of function mutations in NLRP3 gene)
Increased IL-18 found in patients with __
Crohn’s disease
NLRP3-activating crystals in atherosclerosis
Cholesterol crystals
NLRP3-activating crystals in gout
Monosodium urate crystals
NLRP3-activating crystals in kidney dysfunction
Calcium oxalate crystals
3 biologics that target the IL-1 signalling pathway
- Anakinra (IL-1R antagonist)
- Rilonacept (soluble decoy receptor that binds both IL-1β & IL-1α)
- Canakinumab (IL-1β nAb)
Advantage of Canakinumab over Anakinra
Longer half-life (26h vs 4-6h) - less frequent dosing
Pharmacological agents that directly inhibit NLRP3 activation
- MCC950
- Glyburide
- OLT1177 (Dapansutrile)
What is Dapansutrile?
- Orally active β-sulfonyl nitrile molecule that inhibits NLRP3 activation (upstream of ASC), which reduces caspase 1 activity & subsequent IL-1β release
- Good safety profile in patients with gout but quite a high dose needed
What is glyburide?
- Potently inhibits NLRP3 activation (by blocking K⁺ efflux), but requires high doses
- Commonly used to treat T2DM (associated hypoglycaemia)
What is MCC950?
- Diarylsulfonylurea small molecule compound – most potent and specific NLRP3 inhibitor
- Binds NLRP3 and blocks its ability to hydrolyse ATP (causing instability)
- Inhibits ATP-triggered, NLRP3-mediated IL-1β release in monocytes
Main issue with MCC950
Hepatotoxicity
