NOD1 and NOD2: Signaling, Host Defense, and Inflammatory Disease

Caruso, Roberta; Warner, Neil; Inohara, Naohiro; Núñez, Gabriel

doi:10.1016/j.immuni.2014.12.010

Cited by 667 publications

(690 citation statements)

References 134 publications

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“…This has been shown in the context of lung infection of knockout mice and infected BMD macrophages obtained from knockout mice as well as a human epithelial cell line (33,(40)(41)(42)(43). The activation of the MAPK and NF-B pathways is in part dependent upon NOD signaling, which is contingent upon RIP2 (44,45). Thus, in order to assess the impact of NOD signaling on L. pneumophila infection of human macrophages as well as T2S-mediated dampening, we made a stable RIP2 knockdown U937 cell line with a 72% decrease in the protein level, as shown by immunoblotting (Fig.…”

Section: Resultsmentioning

confidence: 90%

The Type II Secretion System of Legionella pneumophila Dampens the MyD88 and Toll-Like Receptor 2 Signaling Pathway in Infected Human Macrophages

2017

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Previously, we reported that mutants of Legionella pneumophila lacking a type II secretion (T2S) system elicit higher levels of cytokines (e.g., interleukin-6 [IL-6]) following infection of U937 cells, a human macrophage-like cell line. We now show that this effect of T2S is also manifest upon infection of human THP-1 macrophages and peripheral blood monocytes but does not occur during infection of murine macrophages. Supporting the hypothesis that T2S acts to dampen the triggering of an innate immune response, we observed that the mitogen-activated protein kinase (MAPK) and nuclear transcription factor kappa B (NF-B) pathways are more highly stimulated upon infection with the T2S mutant than upon infection with the wild type. By using short hairpin RNA to deplete proteins involved in specific pathogen-associated molecular pattern (PAMP) recognition pathways, we determined that the dampening effect of the T2S system was not dependent on nucleotide binding oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible protein I (RIG-I)-like receptors (RLRs), double-stranded RNA (dsRNA)-dependent protein kinase receptor (PKR), or TIR domain-containing adaptor inducing interferon beta (TRIF) signaling or an apoptosis-associated speck-like protein containing a CARD (ASC)-or caspase-4-dependent inflammasome. However, the dampening effect of T2S on IL-6 production was significantly reduced upon gene knockdown of myeloid differentiation primary response 88 (MyD88), TANK binding kinase 1 (TBK1), or Toll-like receptor 2 (TLR2). These data indicate that the L. pneumophila T2S system dampens the signaling of the TLR2 pathway in infected human macrophages. We also document the importance of PKR, TRIF, and TBK1 in cytokine secretion during L. pneumophila infection of macrophages.KEYWORDS Legionella pneumophila, TLR2, cytokine, innate immunity, macrophage, type II secretion L egionella pneumophila, a Gram-negative bacterium that is widespread in aquatic habitats, is the principal agent of Legionnaires' disease pneumonia (1-6). In the lungs, Legionella bacteria invade and grow in resident macrophages and then trigger severe inflammation (2). In macrophages, L. pneumophila evades the degradative lysosomal pathway and replicates to large numbers within a membrane-bound vacuole, the Legionella-containing vacuole (LCV) (7,8). Two protein secretion systems, Lsp type II secretion (T2S) and Dot/Icm type IV secretion (T4S), play major roles in the pathogenesis of L. pneumophila (9, 10). In T2S, protein substrates are first translocated across the inner membrane, and upon the action of the T2S pilus-like apparatus, they then exit the bacterial cell through a specific outer membrane pore (11). Using proteomics and enzymatic assays, we have shown that the T2S system of L. pneumo-

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Section: Resultsmentioning

confidence: 90%

The Type II Secretion System of Legionella pneumophila Dampens the MyD88 and Toll-Like Receptor 2 Signaling Pathway in Infected Human Macrophages

2017

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“…NOD1 and NOD2 are well-characterized NLRs in the NOD signalosome, which upon activation homo-oligomerize and recruit signaling molecules that drive NFκB-dependent and AP1-dependent production of proinflammatory cytokines 23 . Some inflammasomes have been shown to activate caspase-1, convert premature forms of IL1β, IL18, and IL33 to mature forms, and secrete these cytokines into the extracellular space 24 .…”

Section: [H2] Nod-like Receptorsmentioning

confidence: 99%

Innate immunity in diabetes and diabetic nephropathy

2015

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Abstract:The innate immune system consists of several classes of pattern recognition receptors (PRRs), including membrane-bound Toll-like receptors (TLRs) and nucleotide-binding domain leucine-rich oligomerization domain (NOD)-like receptors (NLRs).These receptors detect pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) in the extracellular and intracellular space. Intracellular NLRs constitute inflammasomes, which activate and release caspase-1, IL1β, and IL18 and thus initiate an inflammatory response. Systemic and local low-grade inflammation and release of proinflammatory cytokines are implicated in the development and progression of diabetes mellitus and diabetic nephropathy. TLR2, TLR4, and the NLRP3 inflammasome are critically involved in the inflammatory responses in pancreatic islets, adipose, liver and kidney tissues. This Review discusses how innate immune system-driven inflammatory processes can lead to apoptosis, tissue fibrosis, and organ dysfunction to cause insulin resistance, impaired insulin secretion, and renal failure. We propose that careful targeting of TLR2, TLR4, and NLRP3 signalling pathways may be beneficial for the treatment of diabetes mellitus and diabetic nephropathy. 2 Key points The innate immune system consists of several classes of pattern recognition receptors, including TLRs and NLRs, which detect pathogen-associated and danger-associated molecular patterns and initiate an inflammatory response  TLR2 and TLR4 are the predominant toll-like receptors expressed on pancreatic β cells that trigger an inflammatory response in insulitis during type 1 diabetes mellitus  TLR2 and TLR4 signaling, and activation of NLRP3 inflammasomes results in production of various proinflammatory cytokines that can induce insulin resistance in type 2 diabetes mellitus (T2DM) and obesity  Innate immune responses in T2DM and obesity are modulated by the status of the gut microbiota, autophagy, and adipokines  TLR2, TLR4, NOD2, and NLRP3 inflammasome-mediated inflammation are involved in the perpetuation of inflammation in diabetic nephropathy  The activation of TLRs and NLRs stimulates the expression of MCP-1, which is associated with the progression of diabetic nephropathy [H1] IntroductionThe prevalence of diabetes mellitus is estimated to be 8.3%, affecting ~387 million people as of 2014. The number of patients living with diabetes mellitus is expected to increase to ~592 million by 2035, as reported by the International Diabetes Federation 1 . The incidence of end-stage renal disease (ESRD) is also rapidly increasing worldwide but varies up to 15-fold by country. In 2012, the number of new diagnoses of ESRD worldwide ranged from 25 to 467 patients per million. The proportion of new cases of ESRD with diabetes mellitus as the primary cause also differs by country, with 66% cases reported in Singapore and 12-16% cases reported in Ukraine, Romania, and the Netherlands 2 . Although intensified multifactorial intervention in patients with type 2 diabete...

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“…15 NOD1 contains an N-terminal caspase activation and recruitment domain (CARD) belonging to the death domain (DD) superfamily, a centrally located NOD followed by C-terminal leucine-rich repeats (LRRs). NOD2 shares identical domains with NOD1, except that it contains two N-terminal CARD modules.…”

Section: Modulation Of Innate Immune Signaling By the Ubiquitin Systemmentioning

confidence: 99%

The ubiquitin system: a critical regulator of innate immunity and pathogen–host interactions

Chai

Liu

2016

Cell Mol Immunol

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The ubiquitin system comprises enzymes that are responsible for ubiquitination and deubiquitination, as well as ubiquitin receptors that are capable of recognizing and deciphering the ubiquitin code, which act in coordination to regulate almost all host cellular processes, including host-pathogen interactions. In response to pathogen infection, the host innate immune system launches an array of distinct antimicrobial activities encompassing inflammatory signaling, phagosomal maturation, autophagy and apoptosis, all of which are fine-tuned by the ubiquitin system to eradicate the invading pathogens and to reduce concomitant host damage. By contrast, pathogens have evolved a cohort of exquisite strategies to evade host innate immunity by usurping the ubiquitin system for their own benefits. Here, we present recent advances regarding the ubiquitin system-mediated modulation of host-pathogen interplay, with a specific focus on host innate immune defenses and bacterial pathogen immune evasion.

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NOD1 and NOD2: Signaling, Host Defense, and Inflammatory Disease

Cited by 667 publications

References 134 publications

The Type II Secretion System of Legionella pneumophila Dampens the MyD88 and Toll-Like Receptor 2 Signaling Pathway in Infected Human Macrophages

The Type II Secretion System of Legionella pneumophila Dampens the MyD88 and Toll-Like Receptor 2 Signaling Pathway in Infected Human Macrophages

Innate immunity in diabetes and diabetic nephropathy

The ubiquitin system: a critical regulator of innate immunity and pathogen–host interactions

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