• Helminths
• NLRP3 Inflammasomes
• Plasmodium
• T. gondii
• Trypanosome cruzi

• Humans
• NLR Family, Pyrin Domain-Containing 3 Protein/metabolism
• NLR Family, Pyrin Domain-Containing 3 Protein/immunology
• Inflammasomes/metabolism
• Inflammasomes/immunology
• Animals
• Parasitic Diseases/immunology
• Parasitic Diseases/parasitology
• Parasitic Diseases/metabolism
• Immunity, Innate

• RSPD2024R591 King Saud University (KSU)

• Chagas disease
• Leishmania
• Plasmodium
• Trichomonas
• Trypanosoma
• amoeba
• inflammation
• neutrophil
• protozoan

• PAPIIT IN205523 Universidad Nacional Autónoma de México
• CF-2023-I-610 Consejo Nacional de Humanidades, Ciencias y Tecnologías

• Entamoeba
• lifecycle
• pathogenesis
• stress responses
• virulence

• Humans
• Entamoeba histolytica/genetics
• Virulence
• Ecosystem
• Amebiasis/parasitology
• Intestines

• Cryptosporidium
• Entamoeba
• Giardia duodenalis
• HIF
• Leishmania
• Plasmodium
• hypoxia
• parasite
• protozoa

• Eh-NETs drug targets
• Entamoeba histolytica
• Immunopathology
• Molecular signalling
• NETosis
• Neutrophils
• ROS

• Entamoeba histolytica
• Entamoebiasis/drug therapy
• Entamoebiasis/epidemiology
• Entamoebiasis/physiopathology
• Neutrophils
• Extracellular Traps
• Drug Delivery Systems
• Humans
• Antigens, Nuclear

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a significant component of the innate immune system that plays a vital role in the development of various parasitic diseases. However, its role in hepatic alveolar echinococcosis (HAE) remains unclear.

To investigate the NLRP3 inflammasome and its mechanism of activation in HAE.

We assessed the expression of NLRP3, caspase-1, interleukin (IL)-1β, and IL-18 in the marginal zone and corresponding normal liver of 60 patients with HAE. A rat model of HAE was employed to investigate the role of the NLRP3 inflammasome in the marginal zone of HAE. Transwell experiments were conducted to investigate the effect of Echinococcus multilocularis (E. multilocularis) in stimulating Kupffer cells and hepatocytes. Furthermore, immunohistochemistry, Western blotting, and enzyme-linked immunosorbent assay were used to evaluate NLRP3, caspase-1, IL-1β, and IL-18 expression; flow cytometry was used to detect apoptosis and reactive oxygen species (ROS).

NLRP3 inflammasome activation was significantly associated with ROS. Inhibition of ROS production decreased NLRP3-caspase-1-IL-1β pathway activation and mitigated hepatocyte damage and inflammation.

E. multilocularis induces hepatocyte damage and inflammation by activating the ROS-mediated NLRP3-caspase-1-IL-1β pathway in Kupffer cells, indicating that ROS may serve as a potential target for the treatment of HAE.

• Hepatic alveolar echinococcosis
• Inflammasome
• Inflammation
• Kupffer cell
• NLR family pyrin domain-containing 3 protein
• Reactive oxygen species

• Animals
• Rats
• Inflammasomes/metabolism
• Reactive Oxygen Species/metabolism
• NLR Family, Pyrin Domain-Containing 3 Protein/metabolism
• Interleukin-18
• NLR Proteins
• Echinococcosis, Hepatic
• Pyrin Domain
• Signal Transduction
• Inflammation/metabolism
• Caspase 1/metabolism
• Interleukin-1beta/metabolism

• Inflammasome
• Neutrophils
• Reactive oxygen species
• Snake venom
• l-Amino acid oxidases

• Acetophenones
• Caspase 1/metabolism
• Cytokines/metabolism
• Humans
• Inflammasomes/metabolism
• Inflammation Mediators/metabolism
• Interleukin-1beta/metabolism
• L-Amino Acid Oxidase/metabolism
• L-Amino Acid Oxidase/pharmacology
• Lactate Dehydrogenases/metabolism
• Lipopolysaccharides/pharmacology
• NAD/metabolism
• NADP/metabolism
• NADPH Oxidases/metabolism
• NLR Family, Pyrin Domain-Containing 3 Protein/genetics
• NLR Family, Pyrin Domain-Containing 3 Protein/metabolism
• Neutrophils/metabolism
• Phosphoric Monoester Hydrolases/metabolism
• Protein Kinase C/metabolism
• Reactive Oxygen Species/metabolism
• Snake Venoms/metabolism
• Snake Venoms/pharmacology

• Entamoba histolytica
• gasdermin
• innate immunity
• macrophage
• parasite

• Animals
• Caspase 1
• Cell Membrane
• Entamoeba histolytica
• Parasites
• Pyroptosis

• PJT-173551 CIHR
• PJT-162284 CIHR
• Canadian Institutes of Health Research

A hallmark of Entamoeba histolytica (Eh) invasion in the gut is acute inflammation dominated by the secretion of pro-inflammatory cytokines TNF-α and IL-1β. This is initiated when Eh in contact with macrophages in the lamina propria activates caspase-1 by recruiting the NLRP3 inflammasome complex in a Gal-lectin and EhCP-A5-dependent manner resulting in the maturation and secretion of IL-1β and IL-18. Here, we interrogated the requirements and mechanisms for Eh-induced caspase-4/1 activation in the cleavage of gasdermin D (GSDMD) to regulate bioactive IL-1β release in the absence of cell death in human macrophages. Unlike caspase-1, caspase-4 activation occurred as early as 10 min that was dependent on Eh Gal-lectin and EhCP-A5 binding to macrophages. By utilizing CRISPR-Cas9 gene edited CASP4/1, NLRP3 KO and ASC-def cells, caspase-4 activation was found to be independent of the canonical NLRP3 inflammasomes. In CRISPR-Cas9 gene edited CASP1 macrophages, caspase-4 activation was significantly up regulated that enhanced the enzymatic cleavage of GSDMD at the same cleavage site as caspase-1 to induce GSDMD pore formation and sustained bioactive IL-1β secretion. Eh-induced IL-1β secretion was independent of pyroptosis as revealed by pharmacological blockade of GSDMD pore formation and in CRISPR-Cas9 gene edited GSDMD KO macrophages. This was in marked contrast to the potent positive control, lipopolysaccharide + Nigericin that induced high expression of predominantly caspase-1 that efficiently cleaved GSDMD with high IL-1β secretion/release associated with massive cell pyroptosis. These results reveal that Eh triggered “hyperactivated macrophages” allowed caspase-4 dependent cleavage of GSDMD and IL-1β secretion to occur in the absence of pyroptosis that may play an important role in disease pathogenesis.

A unique feature of Entamoeba histolytica (Eh) infection is the capability to cause symptoms in only a limited subset of individuals. This occurs when Eh breaches intestinal innate host defences and comes in contact with the colonic epithelium and immune cells in the lamina propria to elicit a pro-inflammatory response critical in disease pathogenesis. Macrophages are considered among the first responders that Eh comes in direct contact with to activate caspase-1 by initiating the assembly of the NLRP3 inflammasome complex in a Gal-lectin and EhCP-A5-dependent manner, resulting in processing and release of IL-1β. In this study, we showed that inflammatory caspase-4 was activated earlier than caspase-1 when Eh contacts macrophages independent of the NLRP3 inflammasome complex. More importantly, Eh-induced caspase-4 was essential in regulating bioactive IL-1β secretion in the absence of cell death (pyroptosis) that was induced primarily by the activation of caspase-1. Mechanistically, we reveal that Eh-induced caspase-4 activation was critically important in regulating a measured amount of gasdermin D (GSDMD) cleavage resulting in GSDMD pore formation that facilitated sustained IL-1β secretion from macrophages. This was in marked contrast to LPS + Nigericin stimulated macrophages that robustly activated casapase-1 via the NLRP3 inflammasome that resulted in almost complete cleavage of GSDMD with pore-forming proteins that caused massive pyroptosis. Our study provides new insights on how Eh in contact with macrophages fine tune macrophage responses via the activation of caspase-4/1 to allow the cell to regulate IL-1β release by keeping the cells alive. We believe this mechanism of activating macrophages (termed hyperactivation) is a critically overlooked response in the biology of Eh that may play a major role in disease pathogenesis and host defence.

• Caspase 1/genetics
• Caspase 1/metabolism
• Caspases, Initiator/metabolism
• Entamoeba histolytica/metabolism
• Humans
• Interleukin-1beta
• Intracellular Signaling Peptides and Proteins/genetics
• Intracellular Signaling Peptides and Proteins/metabolism
• Phosphate-Binding Proteins/genetics
• Phosphate-Binding Proteins/metabolism
• Pore Forming Cytotoxic Proteins/metabolism
• Pyroptosis

• PJT-173551 CIHR
• PJT-162284 CIHR
• Natural Sciences and Engineering Research Council of Canada
• Canadian Institutes of Health Research

Respiratory silicosis is a preventable occupational disease that develops secondary to the aspiration of crystalline silicon dioxide (silica) into the lungs, activation of the NLRP3 inflammasome, and IL-1β production. Cathepsin Z has been associated with the development of inflammation and IL-1β production; however, the mechanism of how cathepsin Z leads to IL-1β production is unknown. Here, the requirement for cathepsin Z in silicosis was determined using WT mice and mice deficient in cathepsin Z. The activation of the NLRP3 inflammasome in macrophages was studied using WT and cathepsin Z-deficient bone marrow-derived murine dendritic cells and the human monocytic cell line THP-1. The cells were activated with silica, and IL-1β release was determined using enzyme-linked immunosorbent assay or IL-1β bioassays. The relative contribution of the active domain or integrin-binding domain of cathepsin Z was studied using recombinant cathepsin Z constructs and the α₅ integrin neutralizing antibody. We report that the lysosomal cysteine protease cathepsin Z potentiates the development of inflammation associated with respiratory silicosis by augmenting NLRP3 inflammasome-derived IL-1β expression in response to silica. The secreted cathepsin Z functions nonproteolytically via the internal integrin-binding domain to impact caspase-1 activation and the production of active IL-1β through integrin α₅ without affecting the transcription levels of NLRP3 inflammasome components. This work reveals a regulatory pathway for the NLRP3 inflammasome that occurs in an outside-in fashion and provides a link between extracellular cathepsin Z and inflammation. Furthermore, it reveals a level of NLRP3 inflammasome regulation that has previously only been found downstream of extracellular pathogens.

• NLRP3
• arginine-glycine-aspartic acid (RGD) domain
• cathepsin Z
• inflammasome
• inflammation
• integrin
• interleukin-1 (IL-1)
• silica
• silicosis

• IFN-I
• NF-κB
• NLRP12
• caspase 1
• cell death
• inflammasome

• Animals
• Cell Death/immunology
• Host Microbial Interactions
• Host-Parasite Interactions
• Humans
• Infections/immunology
• Inflammation Mediators/metabolism
• NLR Proteins/genetics
• NLR Proteins/immunology
• NLR Proteins/metabolism
• NLR Proteins/physiology
• Parasitic Diseases/immunology
• Receptors, Pattern Recognition/genetics
• Receptors, Pattern Recognition/immunology
• Signal Transduction
• Viruses/immunology

Macrophages promote early host responses to infection by releasing pro-inflammatory cytokines, and they are crucial to combat amoebiasis, a disease affecting millions of people worldwide. Macrophages elicit pro-inflammatory responses following direct cell/cell interaction of Entamoeba histolytica, inducing NLRP3 inflammasome activation with high-output IL-1β/IL-18 secretion. Here, we found that trophozoites could upregulate peroxiredoxins (Prx) expression and abundantly secrete Prxs when encountering host cells. The C-terminal of Prx was identified as the key functional domain in promoting NLRP3 inflammasome activation, and a recombinant C-terminal domain could act directly on macrophage. The Prxs derived from E. histolytica triggered toll-like receptor 4-dependent activation of NLRP3 inflammasome in a cell/cell contact-independent manner. Through genetic, immunoblotting or pharmacological inhibition methods, NLRP3 inflammasome activation was induced through caspase-1-dependent canonical pathway. Our data suggest that E. histolytica Prxs had stable and durable cell/cell contact-independent effects on macrophages following abundantly secretion during invasion, and the C-terminal of Prx was responsible for activating NLRP3 inflammasome in macrophages. This new alternative pathway may represent a potential novel therapeutic approach for amoebiasis, a global threat to millions.

• Entamoeba histolytica
• NLRP3 inflammasome
• TLR4-binding domain
• macrophage
• peroxiredoxin

Protozoan parasites have led to worldwide devastation because of their ability to cause infectious diseases. They have evolved as successful pathogens in part because of their remarkable and sophisticated ways to evade innate host defenses. This holds true for both intracellular and extracellular parasites that deploy multiple strategies to circumvent innate host defenses for their survival. The different strategies protozoan parasites use include hijacking the host cellular signaling pathways and transcription factors. In particular, the nuclear factor-κB (NF-κB) pathway seems to be an attractive target for different pathogens owing to their central role in regulating prompt innate immune responses in host defense. NF-κB is a ubiquitous transcription factor that plays an indispensable role not only in regulating immediate immune responses against invading pathogens but is also a critical regulator of cell proliferation and survival. The major immunomodulatory components include parasite surface and secreted proteins/enzymes and stimulation of host cells intracellular pathways and inflammatory caspases that directly or indirectly interfere with the NF-κB pathway to thwart immune responses that are directed for containment and/or elimination of the pathogen. To showcase how protozoan parasites exploits the NF-κB signaling pathway, this review highlights recent advances from Entamoeba histolytica and other protozoan parasites in contact with host cells that induce outside-in and inside-out signaling to modulate NF-κB in disease pathogenesis and survival in the host.

• NF-κB – nuclear factor kappa B
• cytokine
• entamoeba histolytica
• innate immunity
• macrophage

While Entamoeba histolytica (Eh)-induced pro-inflammatory responses are critical in disease pathogenesis, the downstream signaling pathways that subsequently dampens inflammation and the immune response remains unclear. Eh in contact with macrophages suppresses NF-κB signaling while favoring NLRP3-dependent pro-inflammatory cytokine production by an unknown mechanism. Cullin-1 and cullin-5 (cullin-1/5) assembled into a multi-subunit RING E3 ubiquitin ligase complex are substrates for neddylation that regulates the ubiquitination pathway important in NF-κB activity and pro-inflammatory cytokine production. In this study, we showed that upon live Eh contact with human macrophages, cullin-1/4A/4B/5 but not cullin-2/3, were degraded within 10 minutes. Similar degradation of cullin-1/5 were observed from colonic epithelial cells and proximal colonic loops tissues of mice inoculated with live Eh. Degradation of cullin-1/5 was dependent on Eh-induced activation of caspase-1 via the NLRP3 inflammasome. Unlike cullin-4B, the degradation of cullin-4A was partially dependent on caspase-1 and was inhibited with a pan caspase inhibitor. Cullin-1/5 degradation was dependent on Eh cysteine proteinases EhCP-A1 and EhCP-A4, but not EhCP-A5, based on pharmacological inhibition of the cysteine proteinases and EhCP-A5 deficient parasites. siRNA silencing of cullin-1/5 decreased the phosphorylation of pIκ-Bα in response to Eh and LPS stimulation and downregulated NF-κB-dependent TNF-α mRNA expression and TNF-α and MCP-1 pro-inflammatory cytokine production. These results unravel a unique outside-in strategy employed by Eh to attenuate NF-κB-dependent pro-inflammatory responses via NLRP3 activation of caspase-1 that degraded cullin-1/5 from macrophages.

The protozoan parasite Entamoeba histolytica (Eh) is the etiologic agent for the disease amebiasis. It is a potent pathogen that deploys an arsenal of virulence factors to trigger and subvert host immune defenses. One of the hallmark features of the disease is amebic colitis and in extreme cases, it can lead to abscesses of the liver and brain. For unknown reasons, the parasite breaches colonic mucosal barriers and invade underlying tissues. The host immune system plays a decisive role in determining the outcome of the disease. At the molecular level, the interaction of Eh with macrophage is a turning point in shaping pro-inflammatory responses. Understanding host-pathogen intricacies at the molecular level is key in determining the complexity of the disease. In the context of amebiasis, the underlying molecular events that occur at the Eh-macrophage intercellular junction are partly unravelled. Here we sought to interrogate the mechanisms by which NF-κB signaling is aborted following Eh-macrophage contact and found two regulatory scaffold proteins, cullin-1 and -5 (cullin-1/5) of the multiple E3 ligase complex, are degraded leading to dampening of NF-κB signaling. During Eh-macrophage contact, cullin-1/4A/4B/5 were rapidly degraded whereas cullin-2/3 were not. The degradation of cullin-1/5 was highly dependent on Eh-induced caspase-1 activation via the NLRP3 inflammasome. In contrast, the degradation of cullin-4A but not cullin-4B, was partially dependent on caspase-1 and was inhibited with a cell-permeable pan caspase inhibitor. Intriguingly, we found that Eh virulence factor EhCP-A1 and EhCP-A4, but not EhCP-A5, played an important role in mediating the degradation of these proteins. Silencing cullin-1/5 decreased the phosphorylation of Iκ-Bα in response to Eh and LPS stimulation that markedly downregulated NF-κB-dependent TNF-α mRNA expression and TNF-α and MCP-1 pro-inflammatory cytokine production. This study unravelled a novel role for Eh-induced NLRP3 inflammasome activation of caspase-1 that intersected with the NF-κB pathway leading to the degradation of the novel substrates cullin-1/5 that regulates NF-κB-dependent pro-inflammatory cytokine production.

• Animals
• Caspase 1/metabolism
• Cullin Proteins/metabolism
• Entamoeba histolytica/immunology
• Entamoeba histolytica/metabolism
• Entamoebiasis/immunology
• Entamoebiasis/metabolism
• Humans
• Macrophages/metabolism
• Mice
• NF-kappa B/metabolism
• Signal Transduction/physiology

• Natural Sciences and Engineering Research Council of Canada
• canadian institutes of health research

We have previously demonstrated the significance of endothelial cell-expressed α5β1 integrin in ischemic stroke, having shown that α5β1 integrin endothelial cell-selective knockout mice are significantly resistance to ischemic stroke injury via preservation of the tight junction protein claudin-5 and subsequent stabilization of the blood–brain barrier (BBB). In addition, inhibition of α5β1 by the small peptide noncompetitive integrin α5 inhibitor, ATN-161, is beneficial in a mouse model of ischemic stroke through reduction of infarct volume, edema, stabilization of the BBB, and reduced inflammation and immune cell infiltration into the brain. In continuation with our previous findings, we have further evaluated the mechanistic role of ATN-161 in vitro and found that oxygen and glucose deprivation and reperfusion (OGD/R)-induced inflammation, oxidative stress, apoptosis, mitochondrial depolarization, and fibrosis attenuate tight junction integrity via induction of α5, NLRP3, p-FAK, and p-AKT signaling in mouse brain endothelial cells. ATN-161 treatment (10 µM) effectively inhibited OGD/R-induced extracellular matrix (ECM) deposition by reducing integrin α5, MMP-9, and fibronectin expression, as well as reducing oxidative stress by reducing mitochondrial superoxide radicals, intracellular ROS, inflammation by reducing NLRP3 inflammasome, tight junction loss by reducing claudin-5 and ZO-1 expression levels, mitochondrial damage by inhibiting mitochondrial depolarization, and apoptosis via regulation of p-FAK and p-AKT levels. Taken together, our results further support therapeutically targeting α5 integrin with ATN-161, a safe, well-tolerated, and clinically validated peptide, in ischemic stroke.

• ATN-161
• Fibrosis
• Mitochondrial integrity
• NLRP3
• OGD/R
• bEND.3 cells

• Entamoeba histolytica
• NETosis
• amoebiasis
• immunity
• inflammation
• neutrophil

• E. histolytica
• NETosis
• amoebiasis
• inflammation
• microbiome
• neutrophil
• parasite

• Antagonists
• Cancer
• Inflammation
• P2X7 receptor
• Purinergic receptors

• Adenosine Triphosphate/metabolism
• Animals
• Antineoplastic Agents/pharmacology
• Antineoplastic Agents/therapeutic use
• Clinical Trials as Topic
• Humans
• Neoplasms/drug therapy
• Purinergic P2X Receptor Antagonists/therapeutic use
• Receptors, Purinergic P2X7/drug effects

• Connexin
• Endothelial cell
• Integrin
• Shear stress
• Stiffness
• Vascular inflammation

• ATP-gated P2X channel.
• Intracellular calcium signaling
• Piezo1
• cavitation bioeffects
• integrin ligation

• P2RX7
• infection
• inflammasome
• inflammatory
• purinergic

• Alarmins/immunology
• Animals
• Bacteria/immunology
• Fungi/immunology
• Helminths/immunology
• Host-Pathogen Interactions/immunology
• Host-Pathogen Interactions/physiology
• Humans
• Inflammation/immunology
• Parasites/immunology
• Receptors, Purinergic P2X7/immunology
• Signal Transduction/immunology
• Viruses/immunology

• K08 AI120806 NIAID NIH HHS
• R01 DA052255 NIDA NIH HHS
• R21 AI152833 NIAID NIH HHS
• HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID)

• amebiasis
• host
• immunity
• microbiota
• protection

• Entamoeba histolytica
• Entamoebiasis/genetics
• Entamoebiasis/immunology
• Entamoebiasis/parasitology
• Entamoebiasis/prevention & control
• Goblet Cells/immunology
• Goblet Cells/parasitology
• Host-Parasite Interactions/immunology
• Humans
• Mucin-2/immunology
• Paneth Cells/immunology
• Pore Forming Cytotoxic Proteins/immunology
• Protozoan Vaccines

• R01 AI026649 NIAID NIH HHS
• R37 AI026649 NIAID NIH HHS

• Autophagy
• Cancer immunotherapy
• Extracellular ATP (eATP)
• Immunogenic cell death (ICD)
• P2X/P2Y receptors
• Purinergic signaling
• Tumor microenvironment (TME)

• Giardia duodenalis
• biofilm
• giardiasis
• microbiota
• pathobiont
• polymicrobial infections
• probiotics
• tissue barrier

• Coronaviruses
• Inflammasomes
• Parasites
• Pathogenic and probiotic bacteria
• Viruses
• Yeasts

• Mϕ
• NLRP3
• caspase
• pro-inflammatory response
• prostaglandin E2

The family of ligand-gated ion channels known as P2X receptors were discovered several decades ago. Since the cloning of the seven P2X receptors (P2X1-P2X7), a huge research effort has elucidated their roles in regulating a range of physiological and pathophysiological processes. Transgenic animals have been influential in understanding which P2X receptors could be new therapeutic targets for disease. Furthermore, understanding how inherited mutations can increase susceptibility to disorders and diseases has advanced this knowledge base. There has been an emphasis on the discovery and development of pharmacological tools to help dissect the individual roles of P2X receptors and the pharmaceutical industry has been involved in pushing forward clinical development of several lead compounds. During the discovery phase, a number of positive allosteric modulators have been described for P2X receptors and these have been useful in assigning physiological roles to receptors. This review will consider the major physiological roles of P2X1-P2X7 and discuss whether enhancement of P2X receptor activity would offer any therapeutic benefit. We will review what is known about identified compounds acting as positive allosteric modulators and the recent identification of drug binding pockets for such modulators.

• P2X receptor
• P2X4
• P2X7
• allosteric modulator
• drug discovery
• pharmacology

• Entamoeba histolytica
• 3D-intestinal model
• inflammation
• secretome
• transcriptome

• Acantamoeba spp
• Entamoeba histolytica
• Naegleria fowleri
• adherens junctions
• desmosomes
• epithelia
• tight junctions

• Acanthamoeba/metabolism
• Acanthamoeba/pathogenicity
• Animals
• Entamoeba histolytica/metabolism
• Entamoeba histolytica/pathogenicity
• Epithelial Cells/metabolism
• Epithelial Cells/parasitology
• Host-Parasite Interactions
• Humans
• Naegleria fowleri/metabolism
• Naegleria fowleri/pathogenicity
• Protozoan Infections/metabolism
• Protozoan Infections/parasitology

• CVB3
• Capsid protein
• Macrophages
• NLRP3
• Viral myocarditis

• Adenosine Triphosphate/metabolism
• Animals
• Caspase 1/metabolism
• Cell Line, Tumor
• Connexins/metabolism
• Enzyme Activation/drug effects
• Humans
• Inflammasomes/metabolism
• Interleukin-1beta/metabolism
• Kinetics
• Ligands
• Macrophages/drug effects
• Macrophages/metabolism
• Mice
• NLR Family, Pyrin Domain-Containing 3 Protein/metabolism
• Nerve Tissue Proteins/metabolism
• Pregnane X Receptor/agonists
• Pregnane X Receptor/metabolism
• Receptors, Purinergic P2X7/metabolism
• src-Family Kinases/metabolism

• R01 ES030197 NIEHS NIH HHS
• R01 GM111381 NIGMS NIH HHS
• R01 CA161879 NCI NIH HHS
• R01 ES025708 NIEHS NIH HHS
• R01 CA222469 NCI NIH HHS

• Anti-citrullinated protein antibodies
• CD147
• IL-1β
• NLRP3 inflammasome
• Rheumatoid arthritis

Entamoeba histolytica is a protozoan parasite that causes amebiasis, which remains a significant cause of morbidity and mortality worldwide. E. histolytica causes tissue destruction which leads to clinical disease. This review outlines some of the recent advances that have furthered our understanding of the processes that lead to the tissue damage caused by E. histolytica.

Recent studies have identified new mechanisms involved in E. histolytica–induced tissue damage. These include (i) new form of contact-dependent killing called trogocytosis; (ii) parasite-produced cytokine, macrophage migration inhibitory factor, that contributes to inflammation; (iii) exploitation of host immune response to promote invasion; and (iv) the contribution of the gut microbiome to clinical disease.

Targeting these mechanisms that result in tissue injury should be a focus of future research for the development of improved preventive and therapeutic strategies for amebiasis.

• Amebiasis
• E. histolytica macrophage migration inhibitory factor
• Invasion
• Microbiome
• Trogocytosis

• cancer
• connexin
• crosstalk
• exosomes
• inflammation
• integrin
• pannexin

• AIM2
• NAIP
• NLRC4
• NLRP1
• NLRP3
• Pyrin
• caspase-1
• caspase-11
• gasdermin
• pyroptosis

• ATP release
• Acid ceramidase
• Adiponectin
• Inflammasome
• Pannexin-1 channel
• Podocytes

• Acid Ceramidase/metabolism
• Adenosine Triphosphate/metabolism
• Adiponectin/metabolism
• Animals
• Aspartic Acid/pharmacology
• Cells, Cultured
• Connexins/metabolism
• Enzyme Activation
• Gluconates/pharmacology
• Lysophospholipids/metabolism
• Mice
• Nerve Tissue Proteins/metabolism
• Podocytes/cytology
• Podocytes/metabolism
• Potassium Channels/drug effects
• Sphingosine/analogs & derivatives
• Sphingosine/metabolism

• R01 DK054927 NIDDK NIH HHS
• R01 DK102539 NIDDK NIH HHS
• R01 DK120491 NIDDK NIH HHS
• R56 DK102539 NIDDK NIH HHS

• Entamoeba histolytica
• Muc2
• Paneth cell
• cryptdins
• defensins
• goblet cell
• ileum
• lysozyme
• mucin
• protozoa

• antimicrobial peptides
• cysteine proteases
• entamoeba histolytica
• epithelium
• inflammasome
• mucus
• tight junction proteins

• extracellular ATP
• inflammation
• inflammatory disease
• lymphocytes
• macrophages
• neurodegenerative diseases
• purinergic signaling
• sepsis

The traditional view of integrins portrays these highly conserved cell surface receptors as mediators of cellular attachment to the extracellular matrix (ECM), and to a lesser degree, as coordinators of leukocyte adhesion to the endothelium. These canonical activities are indispensable; however, there is also a wide variety of integrin functions mediated by non-ECM ligands that transcend the traditional roles of integrins. Some of these unorthodox roles involve cell-cell interactions and are engaged to support immune functions such as leukocyte transmigration, recognition of opsonization factors, and stimulation of neutrophil extracellular traps. Other cell-cell interactions mediated by integrins include hematopoietic stem cell and tumor cell homing to target tissues. Integrins also serve as cell-surface receptors for various growth factors, hormones, and small molecules. Interestingly, integrins have also been exploited by a wide variety of organisms including viruses and bacteria to support infectious activities such as cellular adhesion and/or cellular internalization. Additionally, the disruption of integrin function through the use of soluble integrin ligands is a common strategy adopted by several parasites in order to inhibit blood clotting during hematophagy, or by venomous snakes to kill prey. In this review, we strive to go beyond the matrix and summarize non-ECM ligands that interact with integrins in order to highlight these non-traditional functions of integrins.

• bacteria
• counterreceptor
• disintegrin
• extracellular matrix
• growth factor
• hormone
• immune system
• integrin
• pathogen
• stem cell
• venom
• virus

• microbiota
• inflammasome
• gastrointestinal system
• gastrointestinal diseases

• Fibronectin (FN)
• innate immunity
• integrin β1
• phagocytosis of macrophages
• pulmonary infection disease
• toll-like receptor

• Animals
• Fibronectins/genetics
• Fibronectins/immunology
• Immunity, Innate
• Integrin beta1/metabolism
• Interleukin-6/metabolism
• Lipopolysaccharides/pharmacology
• Macrophages/immunology
• Male
• Mice
• Mice, Inbred C57BL
• Neuropeptides/metabolism
• Peptidoglycan/pharmacology
• Phagocytosis/immunology
• Protein Binding
• Signal Transduction
• Teichoic Acids/pharmacology
• Toll-Like Receptor 2/metabolism
• Toll-Like Receptor 4/metabolism
• Tumor Necrosis Factor-alpha/metabolism
• cdc42 GTP-Binding Protein/metabolism
• rac GTP-Binding Proteins/metabolism
• rac1 GTP-Binding Protein/metabolism
• RAC2 GTP-Binding Protein

• SMOC
• TLR
• adaptive immunity
• inflammasomes
• innate immunity

Intestinal mucus secretion is critical in maintaining mucosal host defense against a myriad of pathogens by preventing direct association with the epithelium. Entamoeba histolytica specifically binds colonic MUC2 mucin and also induces potent hypersecretion from goblet cells; however, characterization of the nature of the mechanisms controlling mucus release remains elusive. In this report, we identify vesicle SNARE vesicle-associated membrane protein 8 (VAMP8) present on mucin granules as orchestrating regulated exocytosis in human goblet cells in response to the presence of E. histolytica. VAMP8 was specifically activated during E. histolytica infection, and ablation of VAMP8 led to impaired mucin secretion. As a consequence, loss of VAMP8 increased E. histolytica adherence to epithelial cells associated with enhanced cell death through apoptosis characterized by caspase 3 and 9 cleavages and DNA fragmentation. With the mucosal barrier compromised in Vamp8^−/− animals, E. histolytica induced an aggressive proinflammatory response with elevated levels of interleukin-1 alpha (IL-1α), IL-1β, and tumor necrosis factor alpha (TNF-α) secretion. This report is the first to characterize regulated mucin exocytosis in intestinal goblet cells in response to a pathogen and the downstream consequences of improper mucin secretion in mucosal barrier defense.

The intestinal tract is exposed to countless substances and pathogens, and yet homeostasis is maintained, in part by the mucus layer that houses the microbiota and spatially separates potential threats from the underlying single layer of epithelium. Despite the critical role of mucus in innate host defense, characterization of the mechanisms by which mucus is secreted from specialized goblet cells in the gut remains elusive. Here, we describe the machinery that regulates mucus secretion as well as the consequence during infection with the colonic pathogen Entamoeba histolytica. Abolishment of the key machinery protein VAMP8 abrogated mucus release in cultured human colonic goblet cells and during E. histolytica infection in Vamp8^−/− mice, which showed enhanced amoeba contact and killing of epithelial cells, triggering a potent proinflammatory response. This report highlights the importance of the VAMP8 secretory machinery in facilitating mucus release from intestinal goblet cells and the dire consequences that occur during disease pathogenesis if these pathways are not functional.

• Entamoeba histolytica
• exocytosis
• goblet cells
• gut inflammation
• innate immunity
• mucin
• pathogenesis

Entamoeba histolytica (Eh) is the causative agent of amebiasis, one of the major causes of dysentery-related morbidity worldwide. Recent studies have underlined the importance of the intercellular junction between Eh and host cells as a determinant in the pathogenesis of amebiasis. Despite the fact that direct contact and ligation between Eh surface Gal-lectin and EhCP-A5 with macrophage α₅β₁ integrin are absolute requirements for NLRP3 inflammasome activation and IL-1β release, many other undefined molecular events and downstream signaling occur at the interface of Eh and macrophage. In this study, we investigated the molecular events at the intercellular junction that lead to recognition of Eh through modulation of the macrophage cytoskeleton. Upon Eh contact with macrophages key cytoskeletal-associated proteins were rapidly post-translationally modified only with live Eh but not with soluble Eh proteins or fragments. Eh ligation with macrophages rapidly activated caspase-6 dependent cleavage of the cytoskeletal proteins talin, Pyk2 and paxillin and caused robust release of the pro-inflammatory cytokine, IL-1β. Macrophage cytoskeletal cleavages were dependent on Eh cysteine proteinases EhCP-A1 and EhCP-A4 but not EhCP-A5 based on pharmacological blockade of Eh enzyme inhibitors and EhCP-A5 deficient parasites. These results unravel a model where the intercellular junction between macrophages and Eh form an area of highly interacting proteins that implicate the macrophage cytoskeleton as a sensor for Eh contact that leads downstream to subsequent inflammatory immune responses.

The protozoan parasite Entamoeba histolytica can establish an enteric infection in human hosts that leads to symptoms ranging from diarrhea to abscesses in the liver and the brain. Host susceptibility to amebic infection is in part determined by the quality and potency of the host immune response that occurs once the parasite overcomes the mucus bilayers and colonic epithelial barriers, and invades underlying tissues. At the cellular level, one of the key events that shape the inflammatory response occurs during direct parasite interaction with host macrophages via surface proteins. The ensuing cascades of intracellular signaling events have only partly been uncovered. Interestingly, only direct interaction between live parasites and macrophages, as opposed to soluble factors or dead parasites, is a prerequisite to the generation of a prompt raging pro-inflammatory response. We have sought to further elucidate the mechanisms by which macrophages distinguish live parasites and found that the macrophage cell skeleton undergoes rapid significant alteration upon Eh contact. Furthermore, we uncovered a previously unknown role for two Eh enzymes in triggering macrophage pro-inflammatory responses. Through this work, we gain a better understanding of the molecular interactions that occur at the macrophage-ameba interface that regulate host inflammatory responses.

• Animals
• Blotting, Western
• Cell Line
• Cytoskeleton/immunology
• Entamoeba histolytica/immunology
• Entamoebiasis/immunology
• Female
• Flow Cytometry
• Host-Parasite Interactions/immunology
• Humans
• Interleukin-1beta/metabolism
• Macrophages/immunology
• Macrophages/parasitology
• Male
• Mice, Inbred C57BL
• Microscopy, Confocal

• Natural Sciences and Engineering Research Council of Canada