Cutting Edge: Heat Shock Protein 60 Is a Putative Endogenous Ligand of the Toll-Like Receptor-4 Complex

Ohashi, Koji; Burkart, Volker; Flohé, Stefanie B.; Kolb, Hubert

doi:10.4049/jimmunol.164.2.558

Cited by 1,467 publications

(990 citation statements)

References 32 publications

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“…These include HMGB1 76 31, uric acid 77 , some HSPs 78 79, some defensins [G] 80 , hyaluronic acid 81 , heparan sulfate 82 , and some fragments of extracellular matrix proteins 70 . Whereas this data may well be correct, caution is warranted because TLRs can be stimulated by microbial contaminants that are easily introduced during the purification of molecules.…”

Section: Receptors For Dampsmentioning

confidence: 99%

How dying cells alert the immune system to danger

2008

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When a cell dies in vivo the event does not go unnoticed. The host has evolved mechanisms to detect the death of cells and rapidly investigate the nature of their demise. If cell death is a result of natural causes, that is, it is part of normal physiological processes, then there is little threat to the organism. In this situation, little else is done other than removing the corpse. However, if cells have died as the consequence of some violence or disease, then both defence and repair mechanisms are mobilized. The importance of this process to host defence and disease pathogenesis has only been appreciated relatively recently. This article will review our current knowledge of these processes.The immune system was recognized in ancient times and rediscovered by Jenner and Pasteur based on its ability to confer protection upon repeat exposure to a pathogen. Through subsequent studies by Von Behring and others it rapidly became apparent that the immune system had the potential to respond not only to whole microorganisms, but to virtually any molecule that was "foreign" to the host. However, whereas injection of such molecules would often provoke a robust immune response, this did not invariably occur. Immunization protocols improved in the 1920s with the discovery by Ramon and Glenny of immunostimulatory molecules (adjuvants [G]) that could boost immune responses to co-administered antigens. Adjuvants were typically of microbial origin and became widely used to promote the effectiveness of immunizations. In the 1960s, Dresser showed that a foreign protein when highly purified would only elicit an immune response if it was admixed with a microbial adjuvant 1 . Injected by itself, the antigen not only failed to elicit immunity but actually induced a state of tolerance 2 . However, the significance of these observations was not well appreciated and adjuvants remained one of those things that everyone used because they were part of standard operating procedures.In 1989 Janeway put these empirical observations into a conceptual framework 3 (Fig. 1). He proposed that the immune system did not respond to all foreign antigens but only to those that are potentially associated with infection. The underlying idea here was that the immune system evolved to protect organisms against microorganisms and this discrimination between infectious versus noninfectious antigens focused defences on real threats rather than innocuous situations.At this time, it was already recognized that in order to stimulate T cell responses, antigens had to first be acquired and presented on MHC molecules of an antigen presenting cell (APC). Moreover, it was further known that APCs also provided additional costimulatory signals necessary to activate T cells. Janeway incorporated these principles into his model (Fig. 1). He postulated that the discrimination between infectious and noninfectious non-self molecules was made by the APCs of the innate immune system through receptors that would recognize pathogen-associated molecular patterns (PAMP...

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Section: Receptors For Dampsmentioning

confidence: 99%

How dying cells alert the immune system to danger

2008

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“…Interestingly, tissue damage in response to ischaemia-reperfusion also requires intact TRL4, again indicating that endogenous TLR4 ligands are produced during local stress [98]. We have previously identified heat shock protein 60 as one such 'danger antigen' [99].…”

Section: Synthesis and Open Questions/suggestions For Studiesmentioning

confidence: 99%

The global diabetes epidemic as a consequence of lifestyle-induced low-grade inflammation

Kolb¹,

2009

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The recent major increase in the global incidence of type 2 diabetes suggests that most cases of this disease are caused by changes in environment and lifestyle. All major risk factors for type 2 diabetes (overnutrition, low dietary fibre, sedentary lifestyle, sleep deprivation and depression) have been found to induce local or systemic low-grade inflammation that is usually transient or milder in individuals not at risk for type 2 diabetes. By contrast, inflammatory responses to lifestyle factors are more pronounced and prolonged in individuals at risk of type 2 diabetes and appear to occur also in the pancreatic islets. Chronic low-grade inflammation will eventually lead to overt diabetes if counter-regulatory circuits to inflammation and metabolic stress are compromised because of a genetic and/or epigenetic predisposition. Hence, it is not the lifestyle change per se but a deficient counter-regulatory response in predisposed individuals which is crucial to disease pathogenesis. Novel approaches of intervention may target these deficient defence mechanisms.

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“…Recognition of endogenous ligands by TLRs is also an area of active investigation due to its potential relevance to autoimmune diseases, noninfectious inflammatory disorders, and elimination of neoplastic or damaged cells. A number of putative endogenous TLR ligands have already been studied in vitro, including heat shock protein 60 (Hsp60), 78 fibronectin, 79 and the extra domain A of fibrinogen. 80 Recent data have also demonstrated that low-molecular weight soluble hyaluronan (sHA) fragments derived from the extracellular matrix at sites of inflammation are able to induce DC maturation in vitro as well as in vivo through TLR4.…”

Section: Future Directionsmentioning

confidence: 99%

Toll-like receptors and their role in experimental models of microbial infection

2003

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Effective host defense against microbial infection depends upon prompt recognition of pathogens, activation of immediate containment measures, and ultimately the generation of a specific and definitive adaptive immune response. The innate immune system of the host is responsible for providing constant surveillance against infection; when confronted by pathogens it deploys a series of rapidly acting antimicrobial effectors while simultaneously instructing the adaptive immune system as to the nature and context of the infectious threat. Pathogen recognition and activation of innate immunity is mediated by members of the Toll-like receptor (TLR) family through detection of conserved microbial structures that are absent from the host. Experimental models of infection using TLR-deficient mice, as well as limited human studies, have clearly demonstrated the critical role of TLRs in host defense against most major groups of mammalian pathogens.

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Cutting Edge: Heat Shock Protein 60 Is a Putative Endogenous Ligand of the Toll-Like Receptor-4 Complex

Cited by 1,467 publications

References 32 publications

How dying cells alert the immune system to danger

How dying cells alert the immune system to danger

The global diabetes epidemic as a consequence of lifestyle-induced low-grade inflammation

Toll-like receptors and their role in experimental models of microbial infection

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