Differential protein modulation by ketoprofen and ibuprofen underlines different cellular response by gastric epithelium.

Ketoprofen L-lysine salt (KLS), is widely used due to its analgesic efficacy and tolerability, and L-lysine was reported to increase the solubility and the gastric tolerance of ketoprofen. In a recent report, L-lysine salification has been shown to exert a gastroprotective effect due to its specific ability to counteract the NSAIDs-induced oxidative stress and up-regulate gastroprotective proteins. In order to derive further insights into the safety and efficacy profile of KLS, in this study we additionally compared the effect of lysine and arginine, another amino acid counterion commonly used for NSAIDs salification, in control and in ethanol challenged human gastric mucosa model. KLS is widely used for the control of post-surgical pain and for the management of pain and fever in inflammatory conditions in children and adults. It is generally well tolerated in pediatric patients, and data from three studies in >900 children indicate that oral administration is well tolerated when administered for up to 3 weeks after surgery. Since only few studies have so far investigated the effect of ketoprofen on gastric mucosa maintenance and adaptive mechanisms, in the second part of the study we applied the cMap approach to compare ketoprofen-induced and ibuprofen-induced gene expression profiles in order to explore compound-specific targeted biological pathways. Among the several genes exclusively modulated by ketoprofen, our attention was particularly focused on genes involved in the maintenance of gastric mucosa barrier integrity (cell junctions, morphology, and viability). The hypothesis was further validated by Real-time PCR.

Mono-ADP-ribosylation of the G protein betagamma dimer is modulated by hormones and inhibited by Arf6.

Mono-ADP-ribosylation is a reversible post-translational modification that can modulate the functions of target proteins. We have previously demonstrated that the ß subunit of heterotrimeric G proteins is endogenously mono-ADP-ribosylated, and once modified, the ßγ dimer is inactive toward its effector enzymes. To better understand the physiological relevance of this post-translational modification, we have studied its hormonal regulation. Here, we report that Gß subunit mono-ADP-ribosylation is differentially modulated by G protein-coupled receptors. In intact cells, hormone stimulation of the thrombin receptor induces Gß subunit mono-ADP-ribosylation, which can affect G protein signaling. Conversely, hormone stimulation of the gonadotropin-releasing hormone receptor (GnRHR) inhibits Gß subunit mono-ADP-ribosylation. We also provide the first demonstration that activation of the GnRHR can activate the ADP-ribosylation factor Arf6, which in turn inhibits Gß subunit mono-ADP-ribosylation. Indeed, removal of Arf6 from purified plasma membranes results in loss of GnRHR-mediated inhibition of Gß subunit mono-ADP-ribosylation, which is fully restored by re-addition of purified, myristoylated Arf6. We show that Arf6 acts as a competitive inhibitor of the endogenous ADP-ribosyltransferase and is itself modified by this enzyme. These data provide further understanding of the mechanisms that regulate endogenous ADP-ribosylation of the Gß subunit, and they demonstrate a novel role for Arf6 in hormone regulation of Gß subunit mono-ADP-ribosylation.

Inhibition of osteoclast activity by complement regulation with DF3016A, a novel small-molecular-weight C5aR inhibitor.

Recent insights have indicated an active role of the complex complement system not only in immunity, but also in bone remodeling. Evidence from knockout mice and observations from skeletal diseases have drawn attention to the C5a/C5aR axis of the complement cascade in the modulation of osteoclast functions and as potential therapeutic targets for treatment of bone pathologies. With the aim to identify novel C5aR regulators, a medicinal chemistry program was initiated, driven by structural information on a minor pocket of C5aR that has been proposed to be a key motif for C5aR intracellular activation. The impact of the peptidomimetic orthosteric C5aR antagonist (PMX-53), of two newly synthesized allosteric C5aR antagonists (DF2593A, DF3016A), and of C5aR down-regulation by specific siRNAs, were examined for regulation of osteoclastogenesis, using a well-validated in-vitro model starting from RAW264.7 precursor cells. Both pharmacological and molecular approaches reduced osteoclast maturation of RAW264.7 cells induced by receptor-activator of nuclear factor kappa-B ligand (RANKL), which limited the transcription of several differentiation markers evaluated by real-time PCR, including nuclear factor of activated T-cell 1, matrix metalloproteinase-9, cathepsin-K, and tartrate-resistant acid phosphatase. These treatments were ineffective on the subsequent step of osteoclast syncytium formation, apparently as a consequence of reduction of C5aR mRNA levels in the course of osteoclastogenesis, as monitored by real-time PCR. Among the C5aR antagonists analyzed, DF3016A inhibited osteoclast degradation activity through inhibition of C5aR signal transduction and transcription. These data confirm the preclinical relevance of this novel therapeutic candidate.