R-flurbiprofen is considered the 'inactive' isomer of the nonsteroidal anti-inflammatory drug (NSAID), flurbiprofen, because it does not inhibit cyclooxygenase (COX) activity. However, previous studies have revealed that it has antinociceptive and antitum or effects not due to epimerization to the cyclooxygenase-inhibiting S-isomer. Here, we show that R-flurbiprofen has additional anti-inflammatory activity comparable with that of dexamethasone in the zymosan-induced paw inflammation model in rats. Different criteria suggest that the observed effects are mediated at least in part through inhibition of NF-kB activation: R-flurbiprofen inhibited i) LPS-induced NF-kB DNA binding activity in RAW 264.7 macrophages, ii) translocation of the p65 subunit of NF-kB into the nucleus of these cells, and iii) zymosan-induced NF-kB-dependent gene transcription in the inflamed paw and spinal cord of rats. S-flurbiprofen produced similar effects but was less potent. In addition, R-flurbiprofen inhibited DNA binding activity of AP-1, another key regulatory transcription factor in inflammatory processes. Because R-flurbiprofen does not cause gastrointestinal mucosal damage or other side effects associated with long-term NSAID or glucocorticoid use, it might be a useful drug in inflammatory or other diseases in which increased or constitutive NF-kB and AP-1 activation are involved in the pathophysiological processes.

Chemokines are seen as the stimuli that largely control leukocyte migration. To assess whether the severely impaired process of cutaneous repair observed in genetically diabetic db/db mice is associated with a dysregulated infiltration of immune cells, we determined the expressional kinetics for the murine growth-regulated oncogene/melanoma growth stimulatory activity homolog macrophage inflammatory protein-2, and the macrophage chemoattractant protein-1, respectively. Wound repair in db/db mice was characterized by a sustained inflammatory response and a prolonged expression of macrophage inflammatory protein-2 and macrophage chemoattractant protein-1. Immuno-histochemistry revealed that keratinocytes at the wound margins expressed macrophage chemoattractant protein-1, whereas macrophage inflammatory protein-2 immunopositive signals were observed only in keratinocytes of hair follicles located adjacent to the wound site. Inactivation studies using neutralizing antibodies against macrophage chemoattractant protein-1 or macrophage inflammatory protein-2 indicated that sustained expression of these chemokines participated in a prolonged presence of neutrophils and macrophages at the wound site during diabetic repair. Furthermore, our data provide evidence that late infiltration (day 13 after injury) of neutrophils and macrophages into wounds in db/db mice was associated with a simultaneous downregulation of mRNA for receptors specific for macrophage inflammatory protein-2 and macrophage chemoattractant protein-1 in these animals.

The role of endogenous inducers of inflammation is poorly understood. To produce the proinflammatory master cytokine interleukin (IL)-1␤, macrophages need double stimulation with ligands to both Toll-like receptors (TLRs) for IL-1␤ gene transcription and nucleotide-binding oligomerization domain-like receptors for activation of the inflammasome. It is particularly intriguing to define how this complex regulation is mediated in the absence of an infectious trigger. Biglycan, a ubiquitous leucine-rich repeat proteoglycan of the extracellular matrix, interacts with TLR2/4 on macrophages. The objective of this study was to define the role of biglycan in the synthesis and activation of IL-1␤. Here we show that in macrophages, soluble biglycan induces the NLRP3/ASC inflammasome, activating caspase-1 and releasing mature IL-1␤ without the need for additional costimulatory factors. This is brought about by the interaction of biglycan with TLR2/4 and purinergic P2X 4 /P2X 7 receptors, which induces receptor cooperativity. Furthermore, reactive oxygen species formation is involved in biglycan-mediated activation of the inflammasome. By signaling through TLR2/4, biglycan stimulates the expression of NLRP3 and pro-IL-1␤ mRNA. Both in a model of non-infectious inflammatory renal injury (unilateral ureteral obstruction) and in lipopolysaccharide-induced sepsis, biglycan-deficient mice displayed lower levels of active caspase-1 and mature IL-1␤ in the kidney, lung, and circulation. Our results provide evidence for direct activation of the NLRP3 inflammasome by biglycan and describe a fundamental paradigm of how tissue stress or injury is monitored by innate immune receptors detecting the release of the extracellular matrix components and turning such a signal into a robust inflammatory response. IL-1␤2 is a proinflammatory master cytokine produced by macrophages in response to inflammatory stimuli, such as LPS. The activity of IL-1␤ is regulated sequentially by synthesis of the 31-kDa precursor pro-IL-1␤, intracellular proteolytic conversion into active IL-1␤ (17 kDa) by the cysteine protease caspase-1, also known as IL-1-converting enzyme (1, 2), and by secretion of IL-1␤ (3). The synthesis of pro-IL-1␤ is initiated by Toll-like receptor (TLR) agonists, whereas ATP stimulates cleavage and maturation of IL-1␤ (4, 5). Activation of caspase-1 requires the assembly and activity of a cytosolic multiprotein complex known as the inflammasome, consisting of nucleotide-binding oligomerization-like receptor family members (NLRs; NLRPs (NLR family, pyrin domain-containing 3), NAIP (NLR family, apoptosis inhibitory protein), and NLRC4 (NLR family caspase recruitment domain-containing 4)) (6), generating functional caspase-1 p20 and p10 subunits (1,7,8). TLRs and NLRs contain leucine-rich repeats (LRRs), which are used as ligand-sensing motifs (9, 10). NLRP3, the best characterized member of NLRs, recruits caspase-1 to the inflammasome via the adapter molecule ASC (apoptosis-associated specklike protein containing caspase activation and r...

The mechanisms linking immune responses and inflammation with tumor development are not well understood. Here we show that the soluble form of the extracellular matrix proteoglycan decorin controls inflammation and tumor growth through PDCD4 (programmed cell death 4) and microRNA (miR) 21 by two mechanisms. First, decorin acted as an endogenous ligand of Toll-like receptor-2 and −4 and stimulated production of proinflammatory molecules, including PDCD4, in macrophages. Second, decorin prevented translational repression of PDCD4 by decreasing the activity of transforming growth factor (TGF) β1 and the abundance of oncogenic miR-21, a translational inhibitor of PDCD4. Moreover, increased PDCD4 resulted in decreased release of the anti-inflammatory cytokine interleukin-10, thereby making the cytokine profile more proinflammatory. This pathway operates in both pathogen-mediated and sterile inflammation as shown here for sepsis and growth retardation of established tumor xenografts. In sepsis, decorin is an early response gene evoked by septic inflammation and decorin concentrations were increased in plasma of septic patients and mice. In cancer, decorin mediated the reduced abundance of anti-inflammatory molecules and increased that of pro-inflammatory molecules, thereby shifting the immune response to a more proinflammatory state that was associated with reduced tumor growth. Thus, by stimulating pro-inflammatory PDCD4 and decreasing the abundance of miR-21, decorin signaling boosts inflammatory activity in sepsis and suppresses tumor growth.

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