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Hypertension is a multifactorial disorder that probably results from the inheritance of a number of susceptibility genes and involves multiple environmental determinants. Existing evidence suggests that the genetic contribution to blood pressure variation is about 30–50%. Although a number of candidate genes have been studied in different ethnic populations, results from genetic analysis are still inconsistent and specific causes of hypertension remain unclear. Furthermore, the abundance of data in the literature makes it difficult to piece together the puzzle of hypertension and to define candidate genes involved in the dynamic of blood pressure regulation. In this review, we attempt to highlight the genetic basis of hypertension pathogenesis, focusing on the most important existing genetic variations of candidate genes and their potential role in the development of this disease. Our objective is to review current knowledge and discuss limitations to clinical applications of genotypic information in the diagnosis, evaluation and treatment of hypertension. Finally, some principles of pharmacogenomics are presented here along with future perspectives of hypertension.

Immune defense at an interface with the external environment reflects the functions of physical and chemical barriers provided by epithelial and immune cells. Resident epithelial cells, such as keratinocytes, produce numerous peptides with direct antimicrobial activity but also provide a physical barrier against invading pathogens and signal the recruitment of circulating immune cells, such as neutrophils. Antimicrobial peptides such as cathelicidin are produced constitutively by neutrophils and are inducible in keratinocytes in response to infection. The multiplicity of antimicrobial peptides and their cellular sources has resulted in an incomplete understanding of the role of cathelicidin production by epithelial cells in cutaneous immune defense. Therefore, this study sought to evaluate keratinocyte antimicrobial activity and the potential contribution of keratinocyte cathelicidin to host protection against two leading human skin pathogens. Wild-type mice and those with a targeted deletion of the cathelicidin gene, Cnlp, were rendered neutropenic prior to cutaneous infection. Interestingly, Cnlp-deficient mice remained more susceptible to group A streptococcus infection than mice with Cnlp intact, suggesting the involvement of epithelial cell-derived cathelicidin in host immune defense. Keratinocytes were then isolated in culture and found to inhibit the growth of Staphylococcus aureus, an effect that was partially dependent on their ability to synthesize and activate cathelicidin. Further, lentivirus-mediated delivery of activated human cathelicidin enhanced keratinocyte antimicrobial activity. Combined, these data illustrate the potential contribution of keratinocyte cathelicidin to the innate immune defense of skin against bacterial pathogens and highlight the need to consider epithelial antimicrobial function in the diagnosis and therapy of skin infection.

ABSTRACTImmune defense at an interface with the external environment reflects the functions of physical and chemical barriers provided by epithelial and immune cells. Resident epithelial cells, such as keratinocytes, produce numerous peptides with direct antimicrobial activity but also provide a physical barrier against invading pathogens and signal the recruitment of circulating immune cells, such as neutrophils. Antimicrobial peptides such as cathelicidin are produced constitutively by neutrophils and are inducible in keratinocytes in response to infection. The multiplicity of antimicrobial peptides and their cellular sources has resulted in an incomplete understanding of the role of cathelicidin production by epithelial cells in cutaneous immune defense. Therefore, this study sought to evaluate keratinocyte antimicrobial activity and the potential contribution of keratinocyte cathelicidin to host protection against two leading human skin pathogens. Wild-type mice and those with a targeted deletion of the cathelicidin gene, Cnlp, were rendered neutropenic prior to cutaneous infection. Interestingly, Cnlp-deficient mice remained more susceptible to group A streptococcus infection than mice with Cnlpintact, suggesting the involvement of epithelial cell-derived cathelicidin in host immune defense. Keratinocytes were then isolated in culture and found to inhibit the growth of Staphylococcus aureus, an effect that was partially dependent on their ability to synthesize and activate cathelicidin. Further, lentivirus-mediated delivery of activated human cathelicidin enhanced keratinocyte antimicrobial activity. Combined, these data illustrate the potential contribution of keratinocyte cathelicidin to the innate immune defense of skin against bacterial pathogens and highlight the need to consider epithelial antimicrobial function in the diagnosis and therapy of skin infection.

Within the last decade, several peptides have been discovered on the basis of their ability to inhibit the growth of potential microbial pathogens. These so-called antimicrobial peptidesparticipate in the innate immune response by providing a rapid first-line defense against infection. Recent advances in this field have shown that peptides belonging to the cathelicidin and defensin gene families are of particular importance to the mammalian immune defense system. This review discusses the biology of these molecules, with emphasis on their structure, processing, expression and function. Current evidence has shown that both cathelicidins and defensins are multifunctional and that they act both as natural antibiotics and as signaling molecules that activate host cell processes involved in immune defense and repair. The abnormal expression of these peptides has also been associated with human disease. Current and future studies are likely to implicate the presence of antimicrobial peptides in several unexplained human inflammatory disorders and to provide novel therapeutic approaches to the treatment of disease. (J Allergy Clin Immunol 2002;110:823-31.)

Apolipoprotein (Apo) E is an important circulating and tissular protein involved in cholesterol homeostasis and many other functions. The common polymorphism in the coding region of the gene, four polymorphisms in the promoter region, other additional single nucleotide polymorphisms, as well as several ApoE variants have been identified. Outside genetic polymorphism effects, ApoE concentration is modulated in human plasma and tissue through many processes: 1) transcription regulation through hormone responsive elements; 2) cytokines; 3) compartmentalization in particles or linkage to HSPG; 4) degradation after oxidation, glycation, and proteolysis; and 5) through many specific and nonspecific receptor interactions. Is the level of ApoE in tissue or plasma critical in different pathologies such as cardiovascular diseases (CVD) or Alzheimer's disease (AD)? ApoE is able to bind to Aβ, tau, to be an antioxidant, to respond to inflammation, and is involved in cholesterol delivery, uptake, and accumulation. In experimental situations ApoE injection or positive modulation decreases cholesterol and triglycerides and improves cognitive impairment. ApoE peptides are involved in immune response. It seems more and more clear that low vs. high plasma concentration should be evaluated in large epidemiological studies. Only after such studies can the question be answered: Is a low or high concentration of ApoE beneficial or dangerous? This fascinating apolipoprotein will then be an interesting marker and/or drug target. Drug Dev. Res. 56:95–110, 2002. © 2002 Wiley‐Liss, Inc.

Lysines in apolipoprotein (apo) E are key factors in the binding of apoE to the low density lipoprotein receptor, and high affinity binding requires that apoE be associated with lipid. To gain insight into this effect, we examined the microenvironments of the eight lysines in the 22-kDa fragment of apoE3 (residues 1–191) in the lipid-free and lipid-associated states. As shown by 1H,13C heteronuclear single quantum coherence nuclear magnetic resonance, lysine resonances in the lipid-free fragment were poorly resolved over a wide pH range, whereas in apoE3·dimyristoyl phosphatidylcholine (DMPC) discs, the lysine microenvironments and protein conformation were significantly altered. Sequence-specific assignments of the lysine resonances in the spectrum of the lipidated 22-kDa fragment were made. In the lipid-free protein, six lysines could be resolved, and all had pKavalues above 10. In apoE3·DMPC complexes, however, all eight lysines were resolved, and the pKavalues were 9.2–11.1. Lys-143 and Lys-146, both in the receptor binding region in helix 4, had unusually low pKavalues of 9.5 and 9.2, respectively, likely as a result of local increases in positive electrostatic potential with lipid association. Shift reagent experiments with potassium ferricyanide showed that Lys-143 and Lys-146 were much more accessible to the ferricyanide anion in the apoE3·DMPC complex than in the lipid-free state. The angle of the nonpolar face of helix 4 is smaller than the angles of helices 1, 2, and 3, suggesting that helix 4 cannot penetrate as deeply into the DMPC acyl chains at the edge of the complex and that its polar face protrudes from the edge of the disc. This increased exposure and the greater positive electrostatic potential created by interaction with DMPC may explain why lipid association is required for high affinity binding of apoE to the low density lipoprotein receptor.

Lipid-free apolipoprotein (apo) A-I contributes to the reverse transport of cholesterol from the periphery to the liver by solubilizing plasma membrane phospholipid and cholesterol. The features of the apolipoprotein required for this process are not understood and are addressed in the current study. Membrane microsolubilization of human fibroblasts is not specific for apo A-I; unlipidated apos A-II, C, and E incubated with the fibroblast monolayers at a saturating concentration of 50 μg/ml are all able to release cholesterol and phospholipid similarly. To determine the properties of the apolipoprotein that drive the process, apo A-I peptides spanning the entire sequence of the protein were utilized; the peptides correspond to the 11- and 22-residue amphipathic α-helical segments, as well as adjacent combinations of the helices. Of the 20 helical peptides examined, only peptides representing the N-and C-terminal portions of the protein had the ability to solubilize phospholipid and cholesterol. Cholesterol efflux to the most effective peptides, 44–65 and 209–241, was approximately 50 and 70%, respectively, of that to intact apo A-I. Deletion mutants of apo E and apo A-I were constructed that have reduced lipid binding affinities as compared with the intact molecule. The proteins, apo A-I (Δ222–243), apo A-I (Δ190–243), apo E3 (Δ192–299) and apo E4 (Δ192–299) all exhibited a decreased ability to remove cellular cholesterol and phospholipid. These decreases correlated with the reduced ability of these proteins to penetrate into a phospholipid monomolecular film. Overall, the results indicate that insertion of amphipathic α-helices between the plasma membrane phospholipid molecules is a required step in the mechanism of apolipoprotein-mediated cellular lipid efflux. Therefore the lipid binding ability of the apolipoprotein is critical for efficient membrane microsolubilization.