Structure-activity relationships of triazolopyridine oxazole p38 inhibitors: identification of candidates for clinical development.

The synthesis, structure-activity relationship, in vivo activity, and metabolic profile for a series of triazolopyridine-oxazole based p38 inhibitors are described. The deficiencies of the lead structure in the series, CP-808844, were overcome by changes to the C4 aryl group and the triazole side-chain culminating in the identification of several potential clinical candidates.

Sepsis and inflammatory insults downregulate IGFBP-5, but not IGFBP-4, in skeletal muscle via a TNF-dependent mechanism.

The purpose of the present study was to determine whether catabolic stimuli that induce muscle atrophy alter the muscle mRNA abundance of insulin-like growth factor binding protein (IGFBP)-4 and -5, and if so determine the physiological mechanism for such a change. Catabolic insults produced by endotoxin (LPS) and sepsis decreased IGFBP-5 mRNA time- and dose-dependently in gastrocnemius muscle. This reduction did not result from muscle disuse because hindlimb immobilization increased IGFBP-5. Continuous infusion of a nonlethal dose of tumor necrosis factor-alpha (TNF-alpha) decreased IGFBP-5 mRNA 70%, whereas pretreatment of septic rats with a neutralizing TNF binding protein completely prevented the reduction in muscle IGFBP-5. The addition of LPS or TNF-alpha to cultured C(2)C(12) myoblasts also decreased IGFBP-5 expression. Although exogenously administered growth hormone (GH) increased IGFBP-5 mRNA 2-fold in muscle from control rats, muscle from septic animals was GH resistant and no such elevation was detected. In contrast, exogenous administration of IGF-I as part of a binary complex composed of IGF-I/IGFBP-3 produced comparable increases in IGFBP-5 mRNA in both control and septic muscle. Concomitant determinations of IGF-I mRNA content revealed a positive linear relationship between IGF-I and IGFBP-5 mRNA in the same muscle in response to LPS, sepsis, TNF-alpha, and GH treatment. Although dexamethasone decreased muscle IGFBP-5, pretreatment of rats with the glucocorticoid receptor antagonist RU486 did not prevent the sepsis-induced decrease in IGFBP-5 mRNA. In contrast, muscle IGFBP-4 mRNA abundance was not significantly altered by LPS, sepsis, or hindlimb immobilization. In summary, these data demonstrate that various inflammatory insults decrease muscle IGFBP-5 mRNA, without altering IGFBP-4, by a TNF-dependent glucocorticoid-independent mechanism. Finally, IGF-I appears to be a dominant positive regulator of IGFBP-5 gene expression in muscle under both normal and catabolic conditions.

Further studies on possible dynorphin involvement in the ovulatory luteinizing hormone surge in the proestrous rat.

A decrease in inhibitory tone of endogenous opioid peptide on the afternoon of proestrus is one event underlying generation of the ovulatory luteinizing hormone (LH) surge, since premature removal of this inhibitory tone (i.e., disinhibition) results in an early onset of the surge. Our laboratory demonstrated that blockade of kappa-opioid receptors in the medial preoptic area (MPOA) advanced the onset of the LH surge on proestrus. Since dynorphin is the endogenous ligand for the kappa-opioid receptor, the present studies examined the possible role of dynorphin in this disinhibition response. 1) Neutralization of endogenous dynorphin peptides, by push-pull perfusion of the MPOA with antibodies specific for dynorphin A1-17 or A1-8 from 1030-1355 h on proestrus, tended to prematurely advance the increase in plasma LH levels normally occurring on this day of the estrous cycle. Although this increase was not statistically significant when compared with controls, plasma LH levels in two antibody-treated rats were sufficiently elevated to cause full ovulation, a response that did not occur in controls. These data suggest that dynorphin A1-7 and A1-8 might have a role in the MPOA, although a minor one, in suppressing LH secretion early on proestrus. MPOA levels of prodynorphin mRNA decreased at 1700-1800 h on proestrus when plasma LH levels were high, compared with values at 1300-1400 h when plasma LH levels were low. This change did not occur on diestrous d 1 when there was no LH surge. 2) MPOA levels of kappa-opioid receptor mRNA did not change on proestrus or diestrous d 1. These results suggest that a reduction in prodynorphin gene expression on the afternoon of proestrus may be one event involved in a possible decrease in dynorphin inhibitory tone on the ovulatory LH surge-generating signal.

The role of prostaglandin E2 receptors in the pathogenesis of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disorder leading to bone and cartilage destruction. A substantial body of evidence suggests that prostaglandin E2 (PGE2) contributes to the pathogenesis of RA, and nonsteroidal anti-inflammatory drugs, inhibitors of the synthesis of PGE2 and other prostanoids, continue to be used in the treatment of this disease. To begin to understand the mechanism by which prostaglandins modulate the pathophysiology of this disease, we examined mice lacking each of the four known PGE2 (EP) receptors after generation of collagen antibody-induced arthritis, an animal model of RA. Homozygous deletion of the EP1, EP2, or EP3 receptors did not affect the development of arthritis, whereas EP4 receptor-deficient mice showed decreased incidence and severity of disease. These animals also showed reduced inflammation as assessed by circulating IL-6 and serum amyloid A levels. Joint histopathology of EP4(-/-) animals revealed reduced bone destruction, proteoglycan loss, and type II collagen breakdown in cartilage compared with EP4(+/+) mice. Furthermore, liver and macrophages isolated from EP4(-/-) animals produced significantly less IL-1 beta and IL-6 than control samples. Thus, PGE2 contributes to disease progression at least in part by binding to the EP4 receptor. Antagonists of this receptor might therefore provide novel agents for the treatment of RA.