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Innate Recognition (innate + recognition)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Innate recognition of intracellular pathogens: detection and activation of the first line of defense

APMIS, Issue 5-6 2009
SIMON B. RASMUSSEN
The innate immune system constitutes the first line of defense against infections and is also important for initiating the development of an adaptive immune response. The innate immune system recognizes microbial infection through germline-encoded pattern recognition receptors, which are responsible for decoding the microbial fingerprint and activating an appropriate response against the invading pathogen. In this review, we present and discuss current knowledge on how the innate immune system recognizes intracellular pathogens, activates intracellular signaling, induces gene expression, and orchestrates the microbicidal response against pathogens with a habitat within host cells. [source]

CD14 contributes to pulmonary inflammation and mortality during murine tuberculosis

IMMUNOLOGY, Issue 2 2008
Catharina W. Wieland
Summary Toll-like receptors play an essential role in the innate recognition of micro-organisms by the host. CD14 is one of the extracellular adaptor proteins required for recognition of Gram-negative bacteria and possibly also Mycobacterium tuberculosis. Therefore, we intranasally infected wild-type (WT) and CD14 knock-out (KO) mice with virulent M. tuberculosis H37Rv. We found no differences in bacterial load in the main target organ lung up to 32 weeks after infection. From 20 weeks onward 57% of WT mice succumbed, whereas all CD14 KO mice survived. The improved outcome of CD14 KO mice was accompanied by reduced pulmonary inflammation; lung cell counts and percentage of inflamed lung tissue were reduced in CD14 WT mice. These data suggest that during chronic infection CD14 KO mice are protected from lethality caused by lung tuberculosis because of a reduction of the inflammatory response. [source]

Activation of human meningeal cells is modulated by lipopolysaccharide (LPS) and non-LPS components of Neisseria meningitidis and is independent of Toll-like receptor (TLR)4 and TLR2 signalling

CELLULAR MICROBIOLOGY, Issue 3 2005
Holly E. Humphries
Summary The interactions of Neisseria meningitidis with cells of the meninges are critical to progression of the acute, compartmentalized intracranial inflammatory response that is characteristic of meningococcal meningitis. An important virulence mechanism of the bacteria is the ability to shed outer membrane (OM) blebs containing lipopolysaccharide (LPS), which has been assumed to be the major pro-inflammatory molecule produced during meningitis. Comparison of cytokine induction by human meningeal cells following infection with wild-type meningococci, LPS-deficient meningococci or after treatment with OM isolated from both organisms, demonstrated the involvement of non-LPS bacterial components in cell activation. Significantly, recognition of LPS-replete OM did not depend on host cell expression of Toll-like receptor (TLR)4, the accessory protein MD-2 or CD14, or the recruitment of LPS-accessory surface proteins heat shock protein (HSP)70, HSP90,, chemokine receptor CXCR4 and growth differentiation factor (GDF)5. In addition, recognition of LPS-deficient OM was not associated with the expression of TLR2 or any of these other molecules. These data suggest that during meningococcal meningitis innate recognition of both LPS and non-LPS modulins is dependent on the expression of as yet uncharacterized pattern recognition receptors on cells of the meninges. Moreover, the biological consequences of cellular activation by non-LPS modulins suggest that clinical intervention strategies based solely on abrogating the effects of LPS are likely to be only partially effective. [source]

Nucleic acid sensing receptors in systemic lupus erythematosus: development of novel DNA- and/or RNA-like analogues for treating lupus

CLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 2 2010
P. Lenert
Summary Double-stranded (ds) DNA, DNA- or RNA-associated nucleoproteins are the primary autoimmune targets in SLE, yet their relative inability to trigger similar autoimmune responses in experimental animals has fascinated scientists for decades. While many cellular proteins bind non-specifically negatively charged nucleic acids, it was discovered only recently that several intracellular proteins are involved directly in innate recognition of exogenous DNA or RNA, or cytosol-residing DNA or RNA viruses. Thus, endosomal Toll-like receptors (TLR) mediate responses to double-stranded RNA (TLR-3), single-stranded RNA (TLR-7/8) or unmethylated bacterial cytosine (phosphodiester) guanine (CpG)-DNA (TLR-9), while DNA-dependent activator of IRFs/Z-DNA binding protein 1 (DAI/ZBP1), haematopoietic IFN-inducible nuclear protein-200 (p202), absent in melanoma 2 (AIM2), RNA polymerase III, retinoic acid-inducible gene-I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5) mediate responses to cytosolic dsDNA or dsRNA, respectively. TLR-induced responses are more robust than those induced by cytosolic DNA- or RNA- sensors, the later usually being limited to interferon regulatory factor 3 (IRF3)-dependent type I interferon (IFN) induction and nuclear factor (NF)-,B activation. Interestingly, AIM2 is not capable of inducing type I IFN, but rather plays a role in caspase I activation. DNA- or RNA-like synthetic inhibitory oligonucleotides (INH-ODN) have been developed that antagonize TLR-7- and/or TLR-9-induced activation in autoimmune B cells and in type I IFN-producing dendritic cells at low nanomolar concentrations. It is not known whether these INH-ODNs have any agonistic or antagonistic effects on cytosolic DNA or RNA sensors. While this remains to be determined in the future, in vivo studies have already shown their potential for preventing spontaneous lupus in various animal models of lupus. Several groups are exploring the possibility of translating these INH-ODNs into human therapeutics for treating SLE and bacterial DNA-induced sepsis. [source]