TLR7: A new sensor of viral infection

Crozat, Karine; Beutler, Bruce

doi:10.1073/pnas.0401347101

Cited by 150 publications

(110 citation statements)

References 26 publications

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“…Unlike TLR2, 4, 5 and 6, which are expressed on the cell surface, TLR3, 7, 8 and 9 reside in endosomal compartments (Hemmi et al, 2002;Jurk et al, 2002;Akira and Takeda, 2004). In particular, TLR7, 8 and 9 form an evolutionary cluster (Crozat and Beutler, 2004;Takeda and Akira, 2005). Their endosomal localization is thought to be crucial for providing self versus non-self discrimination.…”

Section: Ligand Recognition and Expression Patternsmentioning

confidence: 99%

Toll-like receptors and immune regulation: implications for cancer therapy

2008

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Section: Ligand Recognition and Expression Patternsmentioning

confidence: 99%

Toll-like receptors and immune regulation: implications for cancer therapy

2008

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“…[143][144][145] Reviews on oligoribonucleotide TLR7 agonists have been published recently. [146][147][148] The recognition of ssRNA by TLR7 is both sequence-and motif-dependent, [149][150][151][152] and methylation of the 2' hydroxyl group in uridine leads not only to abrogation of TLR7 activation, 153,154 but also appears to antagonize the receptor.…”

Section: Intracellular Tlr7 Activation: Imidazoquinoline Ligandsmentioning

confidence: 99%

Potential adjuvantic properties of innate immune stimuli

et al. 2009

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Just as the prescient comment by Gaston Ramon was relegated to the last footnote of his 1926 paper, 1 so has research on the mechanisms of action of adjuvants, until recently, languished as parenthetical annotations and addenda in the archives of immunology and vaccine development. Ramon defined immunological adjuvants as "substances used in combination with a specific antigen that produced a more robust immune response than the antigen alone." Interestingly enough, he was referring to his empirical findings that the addition of bread crumbs, tapioca, saponin and 'starch oil' to antigenic preparations greatly enhanced antibody responses to diphtheria or tetanus. 2 A year later, the adjuvanticity of aluminum salts (primarily phosphate and hydroxide) was discovered by Glenny and coworkers. 3 In the 83 years that have elapsed, the repertoire of investigational adjuvants has grown to encompass a very wide range of materials, 4 but aluminum salt-based mineral salts (generically, and incorrectly, termed "alum") have remained the only adjuvants currently approved by the FDA. Aluminum salts have enjoyed a good safety record, but they are weak adjuvants for antibody induction and induce a T helper-2 (T H 2)-skewed, rather than a T helper-1 (T H 1) response. 5,6 Furthermore, not only are aluminum salts ineffective at inducing cytotoxic T lymphocyte (CTL) or mucosal IgA antibody responses, but also have a propensity to induce IgE responses, which have been associated with allergic reactions in some subjects. 5,6 Very recent reports implicate the Nalp3 inflammasome, a component of the innate immune response, as the effector limb of alum-associated adjuvanticity. [7][8][9] In 1962, Dresser observed that injection of purified soluble proteins not only failed to stimulate an immune response, but tolerized animals unless a bacterial extract was admixed with the protein immunogen. 10 This led him to redefine adjuvanticity as "a property of a substance which can act as a physiological switch, directing at least some immunologically competent cells to respond by making antibody rather than by becoming immunologically paralyzed by the antigen," 11 confirming Johnson's earlier observations that lipopolysaccharide (LPS) from Gram-negative bacteria exerted potent adjuvant properties, 12 and perhaps paved the way for the subsequent discovery of the wide range of microorganism-derived adjuvants. 13 TLRs are pattern recognition receptors present on diverse cell types that recognize specific molecular patterns present in molecules that are broadly shared by pathogens but distinguishable from host molecules, collectively referred to as pathogen-associated molecular patterns (PAMPs). 14,15 There are 10 TLRs in the human genome;

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“…Recently, RNA-IgG ICs were shown to activate RF-specific B cells via TLR7 [39]. TLR7 binds ssRNA, a viral antigen that acts as a sensor of infection as well as a component of the U1 snRNP splicing complex, a known autoantigen in SLE [61,62]. Aberrantly high expression of TLR7, or an increased burden of ICs and/or apoptotic cells, aggravates disease in lupus-prone mice.…”

Section: A Short History Of Smmentioning

confidence: 99%

The regulation of autoreactive B cells during innate immune responses

Vilen

Rutan

2008

Immunol Res

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Systemic lupus erythematosus (SLE) highlights the dangers of dysregulated B cells and the importance of initiating and maintaining tolerance. In addition to central deletion, receptor editing, peripheral deletion, receptor revision, anergy, and indifference, we have described a new mechanism of B cell tolerance wherein dendritic cells (DCs) and macrophages (MΦs) regulate autoreactive B cells during innate immune responses. In part, DCs and MΦs repress autoreactive B cells by releasing IL-6 and soluble CD40L (sCD40L). This mechanism is selective in that IL-6 and sCD40L do not affect Ig secretion by naïve cells during innate immune responses, allowing immunity in the absence of autoimmunity. In lupus-prone mice, DCs and MΦs are defective in secretion of IL-6 and sCD40L and cannot effectively repress autoantibody secretion suggesting that defects in DC/MΦ-mediated tolerance may contribute to the autoimmune phenotype. Further, these studies suggest that reconstituting DCs and MΦs in SLE patients might restore regulation of autoreactive B cells and provide an alternative to immunosuppressive therapies. KeywordsSystemic lupus erythematosus; B cell tolerance; Autoimmunity; Dendritic cell; Macrophage; Smith antigen Learning tolerance: a B cell's storyA diverse B cell repertoire is critical in combating pathogens, but inherent in generating diversity is the threat of autoimmunity. In the bone marrow, central tolerance mechanisms such as deletion or receptor editing remove high-affinity autoreactive B cells before they exit to the periphery [1][2][3][4][5][6][7][8][9][10]. Those that escape are subject to receptor revision [8,[11][12][13][14], peripheral deletion [15,16], or a shortened lifespan because they fail to enter B cell follicles [17][18][19][20][21][22]. In rare cases, autoreactive B cells are fully functional but indifferent to their specific antigen [23][24][25]. Finally, many low-affinity autoreactive B cells are maintained in an unresponsive state known as anergy. Anergic B cells do not receive sufficient activation signals to differentiate into plasma cells or secrete immunoglobulin (Ig) in response to antigenic or mitogenic stimulation [26][27][28][29]. Their proliferative responses to B cell receptor (BCR) or toll-like receptor (TLR) signaling as well as their lifespans vary in different models [18,[30][31][32][33][34][35]. Some anergic B cells transduce BCR-derived signals [30, 32,[36][37][38][39][40], while others exhibit desensitized BCRs [30, 33,41]. Quiescence is dependent on chronic exposure to self-antigen and occupancy of the BCR [42,43] The affinity and avidity of the antigen-BCR interaction determines whether developing B cells will be deleted, edited, anergized, or ignored [46]. Self-reactive B cells that survive these developmental checkpoints tend to bind self-antigens with low affinity and they remain anergic in the absence of costimulation by cognate T cells. Many of the early transgenic (Tg) models expressed BCRs with high affinities. However, concerns were raised that these models...

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TLR7: A new sensor of viral infection

Cited by 150 publications

References 26 publications

Toll-like receptors and immune regulation: implications for cancer therapy

Toll-like receptors and immune regulation: implications for cancer therapy

Potential adjuvantic properties of innate immune stimuli

The regulation of autoreactive B cells during innate immune responses

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