Malaria-Induced NLRP12/NLRP3-Dependent Caspase-1 Activation Mediates Inflammation and Hypersensitivity to Bacterial Superinfection Rachel Sippy February 24, 2015

Malaria & Superinfections  Malaria & Its Complications  NLRP Review  Caspase-1 & IL-1 β  Paper by Ataide, et al.  Discussion

Malaria & Its Complications

Malaria  Symptoms (uncomplicated)  Fever  Chills  Headache  Malaise  Jaundice, anemia  Severe disease  Seizures  Kidney failure  Coma  Death  ~250 million cases per year worldwide  1.2 million deaths in 2010  Repeat infection contributes to immunity  Treatment available  Resistance to some treatments in some areas  Prevention is key!  Bacterial co-infection is major contributor to morbidity!

Infectious Agent  Five protozoan species: genus Plasmodium  P. falciparum  P. vivax  P. ovale  P. malriae  P. knowlesi  Species vary in ability to cause disease and geographic location

Vector  Malaria is spread by female Anopheles mosquito  30 to 40 species spread malaria parasites  All continents except Antarctica  Some prefer humans for feeding  Some especially efficient at transmission  Insecticide resistance in some species

Disease ProcessImmune ResponseSymptom Infected red blood cells (RBCs) Rupture by macrophagesAnemia Plasmodium GPI, hemozoin, RNA, DNA Detection by PRRs and pro- inflammatory cytokine release Fever Cytokines circulating Adhesion of RBCs Cerebral/respiratory symptoms Parasite sequestration Immune Response & Symptoms

NLRP Review

NLRPs  NOD-like receptor, pyrin domain containing  Cytoplasmic PRRs, interact with NF- K B pathway and/or inflammasome

NLRPs  NLRP12  Can be inflammasome component  Important for Yersinia pestis infection  Not used in Mycobacterium tuberculosis or Klebsiella pneumoniae  Can affect canonical or non-canonical NF- K B pathway  During Salmonella infection, NLRP12 inhibits NF- K B and ERK, aiding bacterial infection Salmonella MyD88 NF- K B TLR

NLRPs  NLRP3  Can be inflammasome component  Inflammasome assembled with K+ influx  Acts as PRR for inflammasome  PAMPs, crystalline molecules, other stimuli  Function during infection depends on microbe

Caspase-1 & IL-1 β

Caspase-1  Controls inflammation  Protease that cleaves cytokine precursors  MyD88 pathway synthesizes pro-caspase 1  pro-caspase-1 is cleaved into active caspase 1  p20 & p10  Inflammasome is responsible for activating pro-caspase-1  Most NLRPs need ASC to bind caspase-1

Caspase-1 & IL-1 β  Induces pyroptosis  Inflammatory cell death  Increased cell size, active caspase-1  Fever!  Cleaves pro-IL-1 β  IL-1 β is active and secreted  Also some other cytokine precursors  NF- K B pathway transcribes pro-IL-1 β  TLRs  MyD88

Paper by Ataide, et al.

Tools  Knockout mice  MyD88 -/-  ASC -/-  Casp-1 -/-  IFN γ -/-  FACS  Assays  FLICA  7AAD  FSC Helps NLRP3/12 Start of NF- K B Cleaves pIL-1 β Membrane damage Active Casp-1 Cell size Preps DC/Macs

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Commentary

References  Ataide, et al. Malaria-Induced NLRP12/NLRP3-Dependent Caspase-1 Activation Mediates Inflammation and Hypersensitivity to Bacterial Superinfection. PLOS Pathogens Jan:10(1):e  Clay, et al. NLR proteins and parasitic disease. Immunol Res Aug;59(1- 3):  Gazzinelli, et al. Innate sensing of malaria parasites. Nat Rev Immunol Nov;14(11):  "Life cycle of the malaria parasite" from Epidemiology of Infectious Diseases. Available at: Copyright © Johns Hopkins Bloomberg School of Public Health. Creative Commons BY-NC-SA.  “The Caspase-1 Inflammasome & its Role in Autoinflammatory Diseases” Available at:  Tuncer, et al. The multifaceted nature of NLRP12. J Leukoc Biol 2014 Dec; 96:  Vanaja et al. Mechanisms of inflammasome activation: recent advances and novel insights. Trends Cell Biol Jan 29. pii: S (14)