The discovery of Toll-like receptors (TLRs) as components that recognize conserved structures in pathogens has greatly advanced understanding of how the body senses pathogen invasion, triggers innate immune responses and primes antigen-specific adaptive immunity. Although TLRs are critical for host defense, it has become apparent that loss of negative regulation of TLR signaling, as well as recognition of self molecules by TLRs, are strongly associated with the pathogenesis of inflammatory and autoimmune diseases. Furthermore, it is now clear that the interaction between TLRs and recently identified cytosolic innate immune sensors is crucial for mounting effective immune responses. Here we describe the recent advances that have been made by research into the role of TLR biology in host defense and disease.

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The role of pattern-recognition receptors in innate immunity: update on Toll-like receptors

Pattern Recognition Receptors and Inflammation

The inflammasome: a molecular platform triggering activation of inflammatory caspases and processing of proIL-beta.

Development of the acute and chronic inflammatory responses known as gout and pseudogout are associated with the deposition of monosodium urate (MSU) or calcium pyrophosphate dihydrate (CPPD) crystals, respectively, in joints and periarticular tissues. Although MSU crystals were first identified as the aetiological agent of gout in the eighteenth century and more recently as a 'danger signal' released from dying cells, little is known about the molecular mechanisms underlying MSU- or CPPD-induced inflammation. Here we show that MSU and CPPD engage the caspase-1-activating NALP3 (also called cryopyrin) inflammasome, resulting in the production of active interleukin (IL)-1beta and IL-18. Macrophages from mice deficient in various components of the inflammasome such as caspase-1, ASC and NALP3 are defective in crystal-induced IL-1beta activation. Moreover, an impaired neutrophil influx is found in an in vivo model of crystal-induced peritonitis in inflammasome-deficient mice or mice deficient in the IL-1beta receptor (IL-1R). These findings provide insight into the molecular processes underlying the inflammatory conditions of gout and pseudogout, and further support a pivotal role of the inflammasome in several autoinflammatory diseases.

/pdf/gout-associated-uric-acid-crystals-activate-the-nalp3-10cpyoz81v.pdf

Gout-associated uric acid crystals activate the NALP3 inflammasome

The TNF and TNF receptor superfamilies: integrating mammalian biology.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is one of a number of well described hereditary periodic febrile syndromes. We report a case in an infant, with a strong family history of this disorder, who presented on day-of-life 4 with high fever, irritability, diarrhea, lethargy, and raised acute phase reactants. An extensive work-up, including a full sepsis evaluation, proved negative. Symptoms resolved spontaneously. Representation with similar symptoms at 7 months of age prompted successful diagnosis after full evaluation. Subsequent genetic mutation analysis has proven positive for the T50M mutation in exon 2 of the TNFRSF1A gene. To our knowledge, this is the youngest reported age of presentation of this rare autoinflammatory disorder which should be considered even at such a young age.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) or familial Hibernian fever: presentation in a four-day-old infant.

IL-17A RNA Aptamer: Possible Therapeutic Potential in Some Cells, More than We Bargained for in Others?

Arthritis is characterized by pain and functional limitation affecting the patients’ quality of life. We performed a clinical study to investigate the efficacy of a betamethasone valerate medicated plaster (Betesil) in improving pain and functional disability in patients with arthritis and osteoarthritis. We enrolled 104 patients affected by osteoarthritis (n = 40) or arthritis (n = 64) in different joints. Patients received diclofenac sodium cream (2 g, four times a day) or a 2.25-mg dose of Betesil applied to the painful joint every night before bedtime for 10 days. Pain and functional disability were assessed, by the Visual Analogue Scale (VAS) and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) scores. Redness was assessed by clinical inspection, and edema by the “fovea sign” method. C-reactive protein (CRP) was also measured; CRP can be used to cost-effectively monitor the pharmacological treatment efficacy and is increased during the acute-phase response, returning to physiological values after tissue recovery and functional restoration. All measurements were at baseline and at 10-day follow-up. At 10-day follow-up, a greater improvement in VAS and WOMAC pain and WOMAC stiffness and functional limitation scores from baseline was observed in patients treated with Betesil compared with diclofenac (all p < 0.01). At 10-day follow-up, improvement in redness, edema, and CRP levels from baseline was also greater in patients treated with Betesil compared with diclofenac (all p < 0.01). This study demonstrates the safety and efficacy of transdermal delivery of betamethasone valerate in patients affected by arthritis and osteoarthritis.

https://link.springer.com/content/pdf/10.1007%2Fs13346-016-0340-9.pdf

Corticosteroid transdermal delivery significantly improves arthritis pain and functional disability.

Inflammasomes are assembled by innate immune sensors that cells employ to detect a range of danger signals and respond with pro‐inflammatory signalling. Inflammasomes activate inflammatory caspases, which trigger a cascade of molecular events with the potential to compromise cellular integrity and release the IL‐1β and IL‐18 pro‐inflammatory cytokines. Several molecular mechanisms, working in concert, ensure that inflammasome activation is tightly regulated; these include NLRP3 post‐translational modifications, ubiquitination and phosphorylation, as well as single‐domain proteins that competitively bind to key inflammasome components, such as the CARD‐only proteins (COPs) and PYD‐only proteins (POPs). These diverse regulatory systems ensure that a suitable level of inflammation is initiated to counteract any cellular insult, while simultaneously preserving tissue architecture. When inflammasomes are aberrantly activated can drive excessive production of pro‐inflammatory cytokines and cell death, leading to tissue damage. In several autoinflammatory conditions, inflammasomes are aberrantly activated with subsequent development of clinical features that reflect the degree of underlying tissue and organ damage. Several of the resulting disease complications may be successfully controlled by anti‐inflammatory drugs and/or specific cytokine inhibitors, in addition to more recently developed small‐molecule inhibitors. In this review, we will explore the molecular processes underlying the activation of several inflammasomes and highlight their role during health and disease. We also describe the detrimental effects of these inflammasome complexes, in some pathological conditions, and review current therapeutic approaches as well as future prospective treatments.

Inflammasome activation: from molecular mechanisms to autoinflammation

The Fifth International Congress on Familial Mediterranean Fever and Systemic Autoinflammatory Diseases (Rome, Italy, 4-8 April, 2008) reviewed developments in the field of innate immunity and discussed their relevance to the pathogenesis of associated diseases. The meeting gathered over 300 participants from 32 countries. New modes of inheritance of autoinflammatory diseases, animal models, novel related genes and the remarkable efficacy of IL-1beta blockage in most of these diseases were emphasized.

Michael F. McDermott

Papers

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) or familial Hibernian fever: presentation in a four-day-old infant.

IL-17A RNA Aptamer: Possible Therapeutic Potential in Some Cells, More than We Bargained for in Others?

Corticosteroid transdermal delivery significantly improves arthritis pain and functional disability.

Inflammasome activation: from molecular mechanisms to autoinflammation

Fifth International Congress on Familial Mediterranean Fever and Systemic Autoinflammatory Diseases