Pharmacogenetics and pharmacogenomics of cholesterol-lowering therapy.

PURPOSE OF REVIEW: To summarize recent findings on pharmacokinetics, pharmacodynamics, drug-drug interactions and influence of lifestyle heterogeneity on adverse events in cholesterol-lowering therapy RECENT FINDINGS: The prevention of cardiovascular disease is critically dependent on lipid-lowery therapy, including statins, cholesterol absorption inhibitors, fibrates and nicotinic acid. Statins are the most prescribed drugs in lipid lowering therapy with variability in response and almost one third of the patients do not meet their treatment goals. The severe adverse effects of treatment with cerivastatin stimulated the search for new genes and gene variations affecting pharmacokinetics, drug-drug interactions and pharmacodynamics. Moreover, instead of monotherapy, combined therapy of statins with ezetemibe and niacin was considered. This led to the identification of CD13, NPC1L1 and HM74A as new targets and CYP2C8 and glucuronidation enzymes as potential targets for drug-drug interactions. Moreover multiple polymorphic sites and pleiotrophic gene targets were reinvestigated in larger cohorts and the relevant pathogenetic factors start to evolve. SUMMARY: Statin therapy is widely used and well tolerated by the majority of patients. To further reduce potential adverse effects and to increase efficacy, combined therapy concepts with ezetimibe or niacin are underway.

Aberrant intestinal expression and allelic variants of mucin genes associated with inflammatory bowel disease.

Loss of intestinal mucosa integrity is an important factor in the pathogenesis of inflammatory bowel disease (IBD). The aim of this study was to characterize expression changes and allelic variants of genes related to intestinal epithelial barrier function in this disease. Therefore, ileal and colonic mucosal biopsies from nonaffected regions of patients with ulcerative colitis (UC) and Crohn's disease (CD), as well as non-IBD probands, were subjected to Affymetrix DNA-microarray analysis. Real-time reverse transcription polymerase chain reaction was used for verification in larger IBD sample numbers. Disturbed mRNA expression was identified for several mucin genes in both disease groups and tissues. A significant downregulation in the colon was obtained for MUC2 in CD and MUC12 in CD and UC. Expression analysis of all dysregulated mucins in a broad human tissue panel revealed dominant epithelial tissue-specific transcription. In silico analysis of the regulatory regions of these mucins indicated nuclear factor kappaB (NFkappaB) binding sites in each promoter. Furthermore, NFkappaB was overrepresented in mucin promoters and a component of a specific combination of transcription factors (composite module). In vivo stimulation experiments in the adenocarcinoma cell line LS174T showed inducible mucin expression by the cytokines tumor necrosis factor-alpha and transforming growth factor-beta, which could be blocked by NFkappaB signaling inhibitors. Allelic discrimination screening obtained statistically significant associations for the MUC2-V116M (P = 0.003) polymorphism with CD and for MUC4-A585S (P = 0.025), as well as MUC13-R502S (P = 0.0003) with UC. These data suggest that the disturbed expression of mucin genes and the connection to the NFkappaB pathway may influence the integrity of the intestine and therefore contribute to the pathophysiology of IBD.

Cloning and characterization of a novel apolipoprotein A-I binding protein, AI-BP, secreted by cells of the kidney proximal tubules in response to HDL or ApoA-I.

Apolipoprotein A-I (apoA-I) is the major apolipoprotein of high-density lipoproteins (HDL) and has an important role in the regulation of the stability, lipid transport, and metabolism of HDL particles. To identify novel proteins that are involved in HDL metabolism, we used mature apoA-I (amino acids 25-267) as a bait for the screening of a human liver two-hybrid cDNA library. Among the identified genes, several encoded known proteins, including serum amyloid A(2a) (SAA(2a)), apoC-I, and phosphodiesterase HCAM1 (PDE1A), found to interact with apoA-I. In addition, we have cloned a novel 29 kDa apoA-I interacting protein, which we named AI-BP (apoA-I binding protein). The AI-BP encoding gene, APOA1BP, which is located on chromosome 1q21, is composed of six exons and five introns and spans 2.5 kb. Northern blot analysis demonstrated ubiquitous expression of the APOA1BP mRNA with the highest expression in kidney, heart, liver, thyroid gland, adrenal gland, and testis. AI-BP protein is not detectable in serum of healthy probands, but serum samples of patients with septic syndromes may contain elevated levels of AI-BP. Significant amounts of AI-BP protein are found in cerebrospinal fluid and urine of healthy probands. The stimulation of cells derived from the kidney proximal tubules with apoA-I or HDL induces a concentration-dependent secretion of AI-BP indicating an important role for AI-BP, in the renal tubular degradation or resorption of apoA-I.