Carboxylated, heteroaryl-substituted chalcones as inhibitors of vascular cell adhesion molecule-1 expression for use in chronic inflammatory diseases

Starting from a simple chalcone template, structure-activity relationship (SAR) studies led to a series of carboxylated, heteroaryl-substituted chalcone derivatives as novel, potent inhibitors of vascular cell adhesion molecule-1 (VCAM-1) expression. Correlations between lipophilicity determined by calculated logP values and inhibitory efficacy were observed among structurally similar compounds of the series. Various substituents were found to be tolerated at several positions of the chalcone backbone as long as the compounds fell into the right range of lipophilicity. The chalcone alpha,beta-unsaturated ketone moiety seemed to be the pharmacophore required for inhibition of VCAM-1 expression. Compound 19 showed significant antiinflammatory effects in a mouse model of allergic inflammation, indicating that this series of compounds might have therapeutic value for human asthma and other inflammatory disorders.

AGIX-4207 [2-[4-[[1-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]thio]-1-methylethyl]thio]-2,6-bis(1,1-dimethylethyl)phenoxy]acetic acid], a novel antioxidant and anti-inflammatory compound: cellular and biochemical characterization of antioxidant activity and inhibition of redox-sensitive inflammatory gene expression

The pathogenesis of chronic inflammatory diseases, including rheumatoid arthritis, is regulated, at least in part, by modulation of oxidation-reduction (redox) homeostasis and the expression of redox-sensitive inflammatory genes including adhesion molecules, chemokines, and cytokines. AGIX-4207 [2-[4-[[1-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]thio]-1-methylethyl]thio]-2,6-bis(1,1-dimethylethyl)phenoxy]acetic acid] is a novel, orally active, phenolic antioxidant and anti-inflammatory compound with antirheumatic properties. To elucidate its anti-inflammatory mechanisms, we evaluated AGIX-4207 for a variety of cellular, biochemical, and molecular properties. AGIX-4207 exhibited potent antioxidant activity toward lipid peroxides in vitro and displayed enhanced cellular uptake relative to a structurally related drug, probucol. This resulted in potent inhibition of cellular levels of reactive oxygen species in multiple cell types. AGIX-4207 selectively inhibited tumor necrosis factor (TNF)-alpha-inducible levels of the redox-sensitive genes, vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1, with less inhibition of E-selectin, and no effect on intracellular adhesion molecule-1 expression in endothelial cells. In addition, AGIX-4207 inhibited cytokine-induced levels of monocyte chemoattractant protein-1, interleukin (IL)-6, and IL-8 from endothelial cells and human fibroblast-like synoviocytes as well as lipopolysaccharide-induced release of TNF-alpha, IL-1beta, and IL-6 from human peripheral blood mononuclear cells. AGIX-4207 did not inhibit TNF-alpha-induced nuclear translocation of nuclear factor of the kappa-enhancer in B cells (NF-kappaB), suggesting that the mechanism of action is independent of this redox-sensitive transcription factor. Taken together, these results provide a mechanistic framework for understanding the anti-inflammatory and antirheumatic activity of AGIX-4207 and provide further support for the view that inhibition of redox-sensitive inflammatory gene expression is an attractive approach for the treatment of chronic inflammatory diseases.

Discovery of Novel Phenolic Antioxidants as Inhibitors of Vascular Cell Adhesion Molecule-1 Expression for Use in Chronic Inflammatory Diseases

Vascular cell adhesion molecule-1 (VCAM-1) mediates recruitment of leukocytes to endothelial cells and is implicated in many inflammatory conditions. Since part of the signal transduction pathway that regulates the activation of VCAM-1 expression is redox-sensitive, compounds with antioxidant properties may have inhibitory effects on VCAM-1 expression. Novel phenolic compounds have been designed and synthesized starting from probucol (1). Many of these compounds demonstrated potent inhibitory effects on cytokine-induced VCAM-1 expression and displayed potent antioxidant effects in vitro. Some of these derivatives (4o, 4p, 4w, and 4x) inhibited lipopolysaccharide (LPS)-induced secretion of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 from human peripheral blood mononuclear cells (hPBMCs) in a concentration-dependent manner in vitro and showed antiinflammatory effects in an animal model. Compounds 4ad and 4ae are currently in clinical trials for the treatment of rheumatoid arthritis (RA) and prevention of chronic organ transplant rejection, respectively.

Discovery of novel heteroaryl-substituted chalcones as inhibitors of TNF-α-induced VCAM-1 expression

Novel chalcone derivatives have been discovered as potent inhibitors of TNF-alpha-induced VCAM-1 expression. Thienyl or benzothienyl substitution at the meta-position of ring B helps boost potency while large substitution at the para-position on ring B is detrimental. Various substitutions are tolerated on ring A. A lipophilicity-potency relationship has been observed in several sub-series of compounds.

Lead discovery of alpha,beta-unsaturated sulfones from a combinatorial library as inhibitors of inducible VCAM-1 expression

alpha,beta-Unsaturated sulfones have been discovered from a combinatorial library as leads for a new series of inhibitors of inducible VCAM-1 expression. Although not essential, further conjugation of the sulfonyl group to another vinyl group or a phenyl group increases the potency dramatically.

Expression of testis angiotensin-converting enzyme is mediated by a cyclic AMP responsive element

Testis angiotensin-converting enzyme (testis ACE), an ACE isozyme that plays an important role in male fertility, is transcribed from a unique promotor active only in developing spermatids. In vitro analysis suggests the importance of a cyclic AMP response element (CRE)-like region within the testis ACE promoter, and similar DNA motifs are important in the expression of a variety of testis-specific genes. In the present study, we examined the effects of mutations in the CRE-like element on testis ACE promoter activity in vivo using transgenic mice. Disruption of this element reduced reporter gene expression to near background levels. In contrast, conversion of the CRE-like element to a consensus CRE-binding site resulted in high level expression of the reporter gene specifically in the testis. These experiments prove that the CRE-like element is essential for testis ACE promoter activity, although it does not appear to be responsible for its tissue specificity. These data provide insight into how a phenotypically differentiated tissue, ie, male gem cells, regulate tissue-specific gene expression.

The role of Angiotensin-converting enzyme in blood pressure control, renal function, and male fertility

Angiotensin-converting enzyme (ACE) is a zinc peptidase that plays a major role in the renin-angiotensin system. In mammals, the enzyme is present as two isozymes: a somatic form involved in blood-pressure regulation and a testis form of unknown function. Mice lacking ACE have been created and shown to have low systolic blood pressures and defects in renal development and function. These mice also have reduced male fertility, implicating the testis isozyme in reproductive function. (Trends Endocrinol Metab 1997;8:181-186). (c) 1997, Elsevier Science Inc.

The critical role of tissue angiotensin-converting enzyme as revealed by gene targeting in mice

Angiotensin-converting enzyme (ACE) generates the vasoconstrictor angiotensin II, which plays a critical role in maintenance of blood pressure in mammals. Although significant ACE activity is found in plasma, the majority of the enzyme is bound to tissues such as the vascular endothelium. We used targeted homologous recombination to create mice expressing a form of ACE that lacks the COOH-terminal half of the molecule. This modified ACE protein is catalytically active but entirely secreted from cells. Mice that express only this modified ACE have significant plasma ACE activity but no tissue-bound enzyme. These animals have low blood pressure, renal vascular thickening, and a urine concentrating defect. The phenotype is very similar to that of completely ACE-deficient mice previously reported, except that the renal pathology is less severe. These studies strongly support the concept that the tissue-bound ACE is essential to the control of blood pressure and the structure and function of the kidney.

Mice lacking angiotensin-converting enzyme have low blood pressure, renal pathology, and reduced male fertility

Mammals produce two isozymes of angiotensin-converting enzyme (ACE). Somatic ACE plays an important role in the control of blood pressure. The function of testis ACE, produced by male and germ cells, is not known. To examine the roles of these isozymes, we used targeted homologous recombination to introduce a modified ACE allele into a mouse line. Mice homozygous for this mutant allele lack both ACE isozymes and have markedly reduced blood pressures. Contrary to a previous report, we found heterozygous male mice to have normal blood pressures. Homozygous mutant mice also have severe renal disease. The renal papilla is markedly reduced, and the intrarenal arteries exhibit vascular hyperplasia associated with a perivascular inflammatory infiltrate. These animals cannot effectively concentrate urine. They also have an abnormally low urinary sodium to potassium ratio despite reduced levels of aldosterone. Homozygous mutant male mice sire significantly smaller litters than wild-type male mice; however, no defect in sperm number, morphology, or motility was detected. ACE-deficient animals demonstrate the role of this enzyme in systemic blood pressure, renal development and function, and male fertility.

Insulin and glucocorticoids regulate IGFBP-1 expression via a common promoter region

Hepatic expression of insulin-like growth factor binding protein-1 is regulated by insulin and glucocorticoids. To study underlying mechanisms, rat hepatocytes in primary culture were transfected with deletion mutants and heterologous promoter constructs, identifying a 41 bp region of the rat insulin-like growth factor binding protein-1 promoter which is sufficient to mediate regulation by both insulin and glucocorticoids. Half maximal suppression of promoter activity by insulin occurred at a physiologic concentration, 5 x 10(-10) M, and regulation by insulin was dominant in that insulin suppressed promoter activity at all dexamethasone concentrations. Transfection of rat hepatocytes in primary culture should be a useful approach for exploring the regulation of gene expression by insulin.

Effects of alpha-thalassemia-2 on the developmental changes of hematological values in children with sickle cell disease from Georgia

The hematology and pathophysiology of sickle cell disease during the postnatal development of younger hemoglobin (Hb) S homozygotes (SS) could be considerably affected by a variability of alpha globin gene numbers. We have documented longitudinal developmental changes of hematological values and hemoglobin composition on 147 patients with SS (alpha alpha/alpha alpha), 64 with SS (-alpha/alpha alpha), and 9 with SS (-alpha/-alpha) between the ages of 1 and 15 years. Non-steady-state data were excluded from these analyses. The number and organization of alpha globin genes was established by gene mapping. As anticipated, mean corpuscular volume and erythrocyte counts correlated with alpha globin gene numbers throughout the 15-year age interval. On the other hand, SS children with alpha alpha/alpha alpha, -alpha/alpha alpha, -alpha/-alpha had similar hemoglobin concentrations up to the ages of 5-10 years. Around the age of 7, the SS patients with -alpha/-alpha developed a higher Hb concentration than that of the SS (-alpha/alpha alpha), which in turn was higher than that of the SS (alpha alpha/alpha alpha). The emergence of this difference coincided with a developmental increase of the mean corpuscular hemoglobin concentration (MCHC) in patients with SS (alpha alpha/alpha alpha) and the decline of Hb F % under 15%. This newly observed developmental change of the MCHC could lead to increased hemolysis and anemia after the age of 5-10 years. It occurs to a smaller extent among SS (-alpha/alpha alpha) or not at all among SS (-alpha/-alpha) such that these two categories of patients have less severe hemolysis and higher hemoglobin levels at older ages. Although the proportion of Hb F was independent of alpha globin gene numbers, the absence of Hb Bart's suggested that alpha-thalassemia promotes the intracellular assembly of Hb F over Hb S tetramers. Thus, the interaction of alpha-thalassemia and Hb F in young SS patients may be more complex than revealed by Hb F levels in cell lysates. Among older SS children (greater than 7 years) alpha-thalassemia and Hb F levels exceeding 15% appear to have additive effects in diminishing the rate of hemolysis.

Different zeta globin gene deletions among black Americans

Four types of chromosomes with a deletion between the human embryonic zeta and psi zeta globin genes were identified among 2.8% of 321 Black Americans from Georgia. Two deletions of approximately 11 kb which differed by about 300 bp occurred on chromosomes with or without a polymorphic Xba I site 5' to the zeta globin gene [(X+) or (X-)]. The deletions are identifiable in Xba I digests of genomic DNA using an alpha or a zeta globin gene probe which yield fragments of 23 kb from (X+)-zeta alpha alpha chromosomes or 27 kb from (X-)-zeta alpha alpha chromosomes. Digestion with other enzymes and probing with both alpha and zeta probes gave fragments typical of the two zeta globin gene deletions previously identified in Polynesians. Among Black Americans, these zeta globin gene deletions have been found in combination with alpha globin gene deletions in trans but not in cis. Homozygotes have not been found. Hematologic data on carriers of the zeta globin gene deletions in association with Hb AS, SS, and SC suggest that these deletions have no effect on the function of the adult alpha globin genes.