IL-6 plays a critical role in the synergistic induction of human serum amyloid A (SAA) gene when stimulated with proinflammatory cytokines as analyzed with an SAA isoform real-time quantitative RT-PCR assay system

Serum amyloid A (SAA) is known to be a precursor of amyloid A (AA) protein in AA (secondary) amyloidosis and SAA1 to be mainly involved in AA amyloidosis. We established an SAA isoform real-time quantitative RT-PCR assay and found that beta-2 microglobulin is more stable as an internal control than GAPDH and beta-actin for our system. Either IL-6 and IL-1beta or IL-6 and TNFalpha, but not IL-1beta and TNFalpha, induced the synergistic induction of SAA1 and SAA2 genes. Anti-IL-6 receptor monoclonal antibody completely inhibited the synergistic induction of SAA1 and SAA2 during triple stimulation with IL-6, IL-1beta, and TNFalpha, but, IL-1 receptor antagonist or anti-TNFalpha monoclonal antibody was only partially inhibited in HepG2, Hep3B, and PLC/PRF/5 cells. Although the SAA1 promoter has no STAT3 consensus sequence, the JAK2 inhibitor-AG490 reduced SAA1 gene expression to 30%, suggesting the involvement of STAT3. We were able to demonstrate that IL-6 plays a critical role in the synergistic induction of human SAA gene when stimulated with proinflammatory cytokines.

Colchicine nonresponsiveness in familial mediterranean fever: clinical, genetic, pharmacokinetic, and socioeconomic characterization

OBJECTIVES

To identify the ethnic, clinical, genetic, and pharmacokinetic correlates of colchicine treatment failure in patients with familial Mediterranean fever (FMF).

METHODS

Fifty-nine FMF patients, unresponsive to a daily dose of > or =2 mg colchicine, were compared with 51 colchicine-responsive patients by clinical, demographic, and socioeconomic assessment, FMF gene (MEditerranean FeVer [MEFV]) mutation and serum amyloid A1 (SAA1) gene polymorphism analysis, and plasma and white blood cell colchicine level determination.

RESULTS

Colchicine responders and nonresponders were comparable with respect to gender, age, duration and onset of the disease, and various demographic parameters. The 2 cohorts were found to carry mainly the M694V MEFV mutation and had a similar number of homozygotes or compound heterozygotes. Predominance of the alpha/beta alleles of SAA1 and comparable plasma and polymorphonuclear colchicine concentrations characterized both groups. Nonresponders were from lower socioeconomic backgrounds, had less education, and a more severe form of disease. A statistically significant 2-fold elevation of colchicine concentration in the mononuclear cells (MNC) of responders was found.

CONCLUSIONS

Colchicine treatment failure in FMF is associated with inadequate colchicine MNC concentration, probably resulting from a genetic defect unrelated to the underlying FMF.

Efficacy of cyclophosphamide combined with prednisolone in patients with AA amyloidosis secondary to rheumatoid arthritis

Secondary amyloid A (AA) amyloidosis is an uncommon yet important complication of rheumatoid arthritis (RA). It is one of the most relentless of the extra-articular features of RA, and suitable treatments have not yet been found. We studied the efficacy of cyclophosphamide (CYC) combined with prednisolone (PSL) in amyloidotic patients who had serum amyloid A (SAA) 1.3 genotype, which is a risk factor for secondary amyloidosis in Japanese RA patients. Fifteen RA patients who were SAA1.3 homo- and heterozygotes with biopsy-confirmed AA amyloidosis were treated with a combination of CYC and PSL. Laboratory variables of C-reactive protein (CRP), rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), serum albumin (Alb), serum creatinine (Cre) and Lansbury's index were carried out by statistical analysis of changes between before and during the medication. According to the Mann-Whitney rank test, CRP, RF, ESR, Alb and Cre levels improved significantly with the combination treatment (p<0.05). Also, paired t-tests showed significance in Lansbury's index between before and during the medication (p=0.007). CYC combined with PSL ameliorated not only laboratory markers but also clinical rheumatoid activity in patients with amyloidosis secondary to RA, whose genotypes were SAA1.3 homo- and heterozygous. CRP, ESR, RF, Alb and Cre will be surrogate markers of therapeutic efficacy. The combination of CYC and PSL appears to be beneficial for Japanese RA patients who are SAA1.3 homo- and heterozygous carriers, associated with secondary AA amyloidosis.

Genetic effects on baseline values of C-reactive protein and serum amyloid a protein: a comparison of monozygotic and dizygotic twins

BACKGROUND

C-Reactive protein (CRP) and serum amyloid A protein (SAA) are exquisitely sensitive acute-phase reactants, but their baseline values are surprisingly constant in individuals in the general population. These values, especially of CRP, are associated with future atherothrombotic events, and the determinants of baseline CRP and SAA concentration are therefore of considerable interest.

METHODS

CRP and SAA concentrations were measured by well-validated automated microparticle capture enzyme immunoassays, standardized on the respective WHO International Reference Standards, in serum from 146 monozygotic and 164 dizygotic healthy female UK twin pairs from the general population, with mean (range) ages of 58.0 (40-69.6) and 55.7 (40-70.3) years, respectively, who were also very closely matched for height, weight, body mass index, blood pressure, and lifestyle variables. Statistical modeling based on variance components analysis was used to estimate the genetic contribution to the observed values.

RESULTS

As reported previously, CRP values were associated with body mass index, smoking, and hormone replacement therapy. After exclusion of the few samples with CRP concentrations >10 mg/L, which indicate an ongoing acute-phase response rather than baseline values, and inclusion of adjustments for all known confounding variables, there was significantly higher correlation of CRP and SAA results among monozygotic than among dizygotic twins. The estimated hereditability (95% confidence interval) of baseline values was 52% (40-62%) for CRP and 59% (49-67%) for SAA.

CONCLUSION

There is a substantial genetic contribution to baseline serum concentrations of CRP and SAA.

Abdominal fat aspiration biopsy and genotyping of serum amyloid A contribute to early diagnosis of reactive AA amyloidosis secondary to rheumatoid arthritis

OBJECTIVE

To detect amyloid deposits in the early phase of illness, we investigated the usefulness of abdominal fat aspiration biopsy along with genotyping of serum amyloid A (SAA) in patients with rheumatoid arthritis (RA).

PATIENTS AND METHODS

We performed abdominal fat aspiration biopsy with phenol Congo red staining and determined inflammatory markers, including CRP and SAA, in 217 patients with an RA history longer than 5 years (mean age, 64.1 +/- 10.6 years). Genotypes of SAA1 and 2 were investigated in 127 patients with RA by a polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

In the abdominal fat aspiration biopsy 17 patients (7.8%) demonstrated amyloid deposits, which were confirmed as AA type by immunostaining on biopsied tissues from other organs, and nine of them showed no clinical symptoms ascribable to amyloidosis. RA patients with amyloidosis showed significantly higher serum levels of CRP (p < 0.05) and SAA (p < 0.0001) than those without amyloidosis. In the genotyping, amyloid deposition was significantly correlated with the frequency of SAA1.3 (p < 0.005 vs. 1.1, p < 0.05 vs. 1.5). Comparison of inflammatory markers between the number of SAA1.3 alleles showed that the SAA/CRP ratio and SAA concentration were higher in the 1.3 homozygote than in the others (p < 0.05). Two patients demonstrated amyloid deposits at the second abdominal fat biopsy one year after the first, and their SAA1 genotypes were 1.3/1.5 and 1.3/1.3.

CONCLUSION

In RA patients confirmed as having SAA1.3, serial examinations with abdominal fat aspiration biopsy might contribute greatly to the early detection of amyloidosis during the long-term follow-up.

Slower clearance of human SAA1.5 in mice: implications for allele specific variation of SAA concentration in human

Serum amyloid A (SAA), the serum precursor of the fibrillar component (AA proteins) in reactive amyloid deposits, is a multigene product. SAA1, the prominent acute phase isotype in serum and also the dominant fibril precursor, has several allelic variants. In Japan, each of the three major alleles (1.1, 1.3 and 1.5) appears with approximately equal frequency. Recent research suggested that allele 1.5 has a positive influence on the serum SAA concentration. To clarify this, in the present study, recombinant human SAA1.1, SAA1.3 and SAA1.5 were produced in an E. coli expression system and those species of reconstituted high density lipoprotein were injected into mice to examine plasma clearance. SAA1.5 disappeared from plasma more slowly than the other two isotypes. This may account for the positive influence of allele 1.5 on the serum SAA concentration.

The amino acid sequence of protein AA from a burro (Equus asinus)

The primary structure of amyloid fibril protein AA of a burro has been determined by Edman degradation. The 80 amino acid residue long protein shows strong resemblance to that of other mammalian AA-proteins and differs from equine protein AA at 5 positions: Burro/horse positions 20 (Q/N), 44 (R,Q, K/K,Q), 59 (G,L/G,A), 61 (Q/E) and 65 (N/R).

Tissue-specific regulation of the human acute-phase serum amyloid A genes, SAA1 and SAA2, by glucocorticoids in hepatic and epithelial cells

The human acute-phase protein serum amyloid A (A-SAA), encoded by the SAA1 and SAA2 genes, is dramatically induced by pro-inflammatory mediators during the acute-phase response to infection or injury. Circulating A-SAA is predominantly synthesized by the liver. However, other tissues are the source of locally produced A-SAA. Here, we establish that the qualitative and kinetic aspects of SAA1 and SAA2 transcription following treatment of HepG2 hepatoma cells and KB epithelial cells with glucocorticoids and cytokines are quite distinct. Untreated HepG2 cells do not express A-SAA mRNA and glucocorticoids, when administered alone, fail to induce either SAA1 or SAA2. In contrast, untreated KB cells constitutively express SAA1 mRNA. Following cytokine stimulation, both A-SAA genes are rapidly up-regulated to similar extents. As in the hepatoma cell line, co-stimulation of KB cells with glucocorticoids places SAA1 at a transcriptional advantage over SAA2. Interestingly, SAA1 can be significantly induced by glucocorticoids alone in KB cells. The effects of glucocorticoids on SAA1 in both cell lines is glucocorticoid receptor-dependent. Differential regulation of A-SAA expression in these cell lines may reflect different temporal and spatial requirements for A-SAA synthesis in response to different inflammatory challenges.

Amyloid-enhancing factor mediates amyloid formation on fibroblasts via a nidus/template mechanism

OBJECTIVE

To determine the mechanism by which amyloid-enhancing factor (AEF) promotes amyloid deposition, and to test whether AEF seeds deposition of serum amyloid A (SAA) and facilitates conversion to beta-sheet structure.

METHODS

Fibroblasts were cultured with mouse recombinant SAA1.1 and AEF, SAA1.1, or AEF. AEF was prepared as a glycerol extract of spleen from amyloidotic mice. Amyloid was identified by staining with Congo red and examining for green birefringence under polarized light. SAA was localized immunohistochemically. Texas Red-labeled SAA was visualized in living cultures by fluorescence confocal microscopy. AEF was characterized by Western blot analysis using anti-SAA antiserum and N-terminal sequence analysis. Subunits comprising amyloid in fibroblast cultures were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

RESULTS

Amyloid was produced in fibroblast cultures by an AEF-dependent mechanism. AEF, added to culture medium as insoluble protein precipitates, adhered to fibroblast monolayers. SAA bound preferentially to the adherent precipitates. Coincident with SAA binding, precipitates developed an affinity for Congo red. Over time, as more SAA was added, networks of Congo red-positive material producing bright green birefringence also developed outward from AEF precipitates. Amyloid built upon AEF in this manner was composed of full-length SAA. No amyloid was produced in cultures treated with either SAA or AEF alone. SAA and SAA peptides processed in the C-terminal region were the most prominent proteins in the glycerol-extracted AEF preparation.

CONCLUSION

AEF binds to fibroblast monolayers and acts as a sink for SAA. SAA that collects on AEF assembles into an amyloid structure. Thus, it is concluded that AEF serves as both a nidus and a template for amyloid formation.

Maternal glucocorticoids increase endotoxin-induced lung inflammation in preterm lambs

Antenatal betamethasone (Beta) is widely used in women with asymptomatic chorioamnionitis at risk for preterm delivery, but its effects on fetal inflammation are unstudied. Groups of ewes at 109 +/- 1 days of gestation received the following treatments: intra-amniotic (IA) saline (control), 0.5 mg/kg intramuscular Beta, 10 mg IA endotoxin (Endo), and Beta + 2 h later Endo (Beta + Endo). Beta suppressed Endo-induced lung inflammation at 1 day. However, compared with Endo 5 days after treatment, Beta + Endo lambs had increased alveolar neutrophils, proinflammatory cytokine mRNA expression, and serum amyloid A3 (SAA3) mRNA expression. IL-1beta mRNA expression was localized to the inflammatory cells, whereas SAA3 mRNA expression was induced in the bronchial epithelium and the inflammatory cells. Compared with Endo, Beta + Endo lambs had increased lung inflammation but equivalent lung volumes 15 days after treatment. The late increase in inflammation in the Beta + Endo animals suggests that glucocorticoids impair the ability of the preterm lung to downregulate Endo-induced inflammation after fetal clearance of the glucocorticoids. These results have implications for lung inflammation and bronchopulmonary dysplasia in preterm infants exposed to chorioamnionitis and maternal glucocorticoids.

An allele of serum amyloid A1 associated with amyloidosis in both Japanese and Caucasians

Serum amyloid A1 (SAA1), one of the two isotypes of acute phase SAA, is the predominant precursor to amyloid A (AA) protein, the chief constituent of fibrillar deposits in reactive (AA) amyloidosis. Prolonged hyperexpression of SAA protein accompanying chronic inflammation is critical to, but seems not to be sufficient for, the development of AA amyloidosis. Several previous studies have investigated the possibility of linkage between SAA1 exon 3 polymorphisms and susceptibility to amyloidosis. While the SAA1.1 allele was found to have a negative association with amylodosis in Japanese subjects, it showed a positive association in Caucasians. Moriguchi and colleagues recently showed that a single nucleotide polymorphism (SNP) at position -13 in the SAA1 5' flanking region was more strongly associated with amyloidosis than was the exon 3 polymorphism. To test whether this SNP may be an amyloidogenic factor common to Japanese and Caucasians, we have analyzed the SAA1 gene in amyloid and non-amyloid patients of both ethnic groups for the presence of T or C at position -13 and for exon 3 polymorphisms (SAA1.1, 1.3 or 1.5). The frequency of the -13T allele was 0.708 and 0.521 in Japanese rheumatoid arthritis patients with and patients without AA amyloidosis, respectively, and 0.536 and 0.196 in American Caucasian patients with AA amyloidosis and control subjects, respectively. In Caucasians, the -13T allele had a stronger association with amyloidosis than did the SAA1.1 allele. These findings suggest that -13T is a genetic background for AA amyloidosis in both Japanese and Caucasians and the difference in prevalence of AA amyloidosis in the two ethnic groups may be due, at least in part, to a difference in the frequency of the -13T SAA1 allele.

Serum amyloid A1 and tumor necrosis factor-alpha alleles in Turkish familial Mediterranean fever patients with and without amyloidosis

The major complication of familial Mediterranean fever (FMF) is AA amyloidosis. The influence of FMF gene (MEFV) mutations and/or unknown environmental factors and other genetic modifiers are likely to affect the phenotypic variations of the disease and the development of amyloidosis. Serum amyloid A is a serum precursor of AA amyloid that is induced by inflammatory cytokines including TNF-alpha. Our analysis of SAA1.1 frequency in Turkish FMF-amyloidosis patients, revealed a higher frequency compared to non FMF-amyloidosis patients but the difference was not significant. On the other hand, the distribution of SAA1.1 homozygosity among FMF-amyloidosis patients was 55.5% compared to FMF-non-amyloidosis patients (30.8%) which was statistically significant revealing a 2.5 fold risk for the occurrence of amyloidosis. There was no significant difference between the controls and FMF patients with and without amyloidosis for the TNF-alpha-308 G-A allele. It is worth noting that all TNF-alpha-308 G-A carriers (n = 6) in FMF-amyloidosis group have SAA1.1 homozygosity compared to 2/11 in FMF-non-amyloidosis group. Further evaluation of these polymorphisms may have importance and need further study.

Induction of human mammary-associated serum amyloid A3 expression by prolactin or lipopolysaccharide

In most mammalian species, serum amyloid A isoform 3 (SAA3) appears to be the predominant SAA isoform expressed extrahepatically. However, human SAA3 gene expression has not been detected previously and, therefore, this gene was referred to as a pseudogene. We report for the first time the transcriptional expression of human SAA3. Human SAA3 gene expression was detected by RT-PCR after stimulation of mammary gland epithelial cells with either prolactin (PRL) or lipopolysaccharide (LPS). The full-length 655bp cDNA sequence for this mammary-associated serum amyloid A3 (M-SAA3) was obtained using 5' and 3' rapid amplification of cDNA ends (RACE). The human M-SAA3 transcript would conceptually translate into a 42 residue mature protein, which is smaller than other mammalian SAA3 isoforms that are typically 104-113 amino acids in length. This study defines the cDNA sequence for human SAA3 and also demonstrates the upregulation of M-SAA3 expression in response to the lactational hormone PRL or to an acute phase stimulant such as LPS.

Estimation of haplotype frequencies, linkage-disequilibrium measures, and combination of haplotype copies in each pool by use of pooled DNA data

Inference of haplotypes is important for many genetic approaches, including the process of assigning a phenotype to a genetic region. Usually, the population frequencies of haplotypes, as well as the diplotype configuration of each subject, are estimated from a set of genotypes of the subjects in a sample from the population. We have developed an algorithm to infer haplotype frequencies and the combination of haplotype copies in each pool by using pooled DNA data. The input data are the genotypes in pooled DNA samples, each of which contains the quantitative genotype data from one to six subjects. The algorithm infers by the maximum-likelihood method both frequencies of the haplotypes in the population and the combination of haplotype copies in each pool by an expectation-maximization algorithm. The algorithm was implemented in the computer program LDPooled. We also used the bootstrap method to calculate the standard errors of the estimated haplotype frequencies. Using this program, we analyzed the published genotype data for the SAA (n=156), MTHFR (n=80), and NAT2 (n=116) genes, as well as the smoothelin gene (n=102). Our study has shown that the frequencies of major (frequency >0.1 in a population) haplotypes can be inferred rather accurately from the pooled DNA data by the maximum-likelihood method, although with some limitations. The estimated D and D' values had large variations except when the /D/ values were >0.1. The estimated linkage-disequilibrium measure rho2 for 36 linked loci of the smoothelin gene when one- and two-subject pool protocols were used suggested that the gross pattern of the distribution of the measure can be reproduced using the two-subject pool data.

Lipopolysaccharides induce intestinal serum amyloid A expression in the sea cucumber Holothuria glaberrima

We have previously characterized the first invertebrate homolog of serum amyloid A (SAA) proteins in the sea cucumber Holothuria glaberrima, where its expression is associated with intestinal regeneration, suggesting a possible involvement of SAA proteins in intestinal morphogenesis. Here we show that bacterial lipopolysaccharides (LPS) trigger a coelomocyte-mediated immune response in H. glaberrima, inducing an approximately threefold increase in coelomocyte phagocytic activity. Furthermore, LPS induces an approximately fourfold increase in SAA mRNA levels in non-regenerating intestines. These results show that in H. glaberrima, LPS act as an immune activator and that SAA expression can be modulated by immune-associated processes.

[Eight years of amyloid research in chickens: a review]

The articular localisation of amyloid is not uncommon in Galliformes. In commercial brown layer chickens amyloid artropathy was first described in 1994 as a clinical problem with increasing importance associated with growth depression and lameness. Considering the clinical veterinary and the scientific relevance of amyloid artropathy, it was a subject of poultry research during the past eight years. The outcome of the various studies performed is described in the present update. The occurrence, nature, pathogenesis and possible etiological factors of chicken amyloid artropathy, the identification and characterization of the chicken joint amyloid protein and the gene involved are reported. Finally, the results of immunological studies, which provide a plausible explanation for the difference in breed susceptibility, and summarising conclusions are presented.

Differential transcription of the mouse acute phase serum amyloid A genes in response to pro-inflammatory cytokines

The acute phase members of the mouse serum amyloid A (Saa) family, Saa1, Saa2 and Saa3, are highly similar at both the nucleotide and protein sequence levels. Saa1 and Saa2 in the BALB/c strain are 72% identical over the first 500 bp upstream of their transcription start sites and to date have been considered to be coordinately regulated. Furthermore, based on their homology with the upstream regions of the human SAA1 and SAA2 genes, it has been assumed that they are Type I acute phase proteins (APPs), i.e. they are primarily regulated by IL-1 and TNF. Here we establish that the BALB/c Saa1, Saa2 and Saa3 genes, in fact, respond differently to IL-1, TNF and IL-6. The Saa1 and Saa2 promoters are strongly induced by IL-6, with synergistic upregulation of Saa2, but not of Saa1, by IL-1 or TNF. In contrast, the Saa3 promoter is strongly induced by IL-1, moderately induced by TNF and only minimally induced by IL-6. We also define important sequence differences between the Saa promoters of Type A (BALB/c and ICR/Swiss) and Type B (129/Ola) strains of mice, that have dramatic qualitative and quantitative consequences for Saa1 and Saa2 regulation. These findings mandate careful strain selection prior to embarking on studies involving mouse models of secondary amyloidosis or cytokine inactivation.

[Secondary amyloidosis in patients with rheumatoid arthritis(RA)]

The amyloidoses are a group of protein deposition diseases in which amyloid proteins composed of insoluble fibrils are deposited in various organs. Most cases of the secondary amyloidosis(AA amyloidosis) in which amyloid A(AA) protein is deposited followed by uncontrolled, long term RA(duration 7 to 10 years). It has been revealed that the multi-organ dysfunction associated with AA amyloidosis causes the deterioration of RA prognosis. Since the mechanism of amyloid protein deposition is still unknown, the diagnosis of AA amyloidosis is difficult and there is no fundamental therapy for it; there are only supportive therapies for the malfunction of involved organs.

Transcriptional regulation of serum amyloid A1 gene expression in human aortic smooth muscle cells involves CCAAT/enhancer binding proteins (C/EBP) and is distinct from HepG2 cells

Regulation of acute-phase serum amyloid A (A-SAA) synthesis by proinflammatory cytokines and steroid hormones in human aortic smooth muscle cells (HASMCs) is distinct from that in HepG2 cells. To study the cis- and trans-activating promoter element involved in the SAA1 gene expression by HASMCs and HepG2 cells, we constructed plasmid vectors for luciferase reporter gene assay with varying lengths of SAA1 upstream regulatory region (up to 1431 bp), and examined their response to proinflammatory cytokines and/or steroid hormones. The corresponding vectors with the SAA4 upstream regulatory region served as controls. The presence of proposed transcriptional regulatory factors binding to these regions was confirmed immunohistochemically. The sequences of 1478 and 1836 bp of the SAA1 and SAA4 5'-flanking regions were determined, respectively. SAA1 promoter transcription in cultured HASMCs was upregulated not by proinflammatory cytokines, but rather by glucocorticoids. This differed from HepG2 cells, in which SAA1 promoter transcription was upregulated synergistically by proinflammatory cytokines and glucocorticoids. The promoter activity of a series of truncated SAA1 promoter constructs measured using the reporter gene assay showed that the 5'-region from -252 to -175, containing a consensus site for CCAAT/enhancer binding proteins alpha,beta (C/EBPalpha,beta), was essential for SAA1 induction in HASMCs. In HepG2 cells, the 5'-region from -119 to -79, containing a nuclear factor kappa-B (NFkappaB) consensus sequence, was essential for the induction. The functional significance of the C/EBP site as indicated by the immunohistochemical result was that in HASMCs anti-C/EBPbeta reactivity was shifted from the cytoplasm to the nuclei. We have, therefore, demonstrated that the region containing the C/EBPalpha,beta consensus binding site between the bases -252 and -175 is important for the glucocorticoid-induced SAA1 gene expression in HASMCs but not in HepG2 cells.

Differential glucocorticoid enhancement of the cytokine-driven transcriptional activation of the human acute phase serum amyloid A genes, SAA1 and SAA2

The human acute phase serum amyloid A (A-SAA) genes, SAA1 and SAA2, have a high degree of sequence identity that extends approximately 450 bp upstream of their transcription start sites. Each promoter contains analogously positioned functional binding sites for the transcription factors NF-kappaB and NF-IL6. In human HepG2 hepatoma cells transfected with SAA promoter luciferase reporter constructs, administration of IL-1 and IL-6, singly or in combination, induced SAA1 and SAA2 transcriptional readouts that were qualitatively indistinguishable. However, under induced conditions, the SAA2 promoter had a significant quantitative transcriptional advantage over the SAA1 promoter. The application of the synthetic glucocorticoid dexamethasone in the context of cytokine stimulation enhanced the transcriptional activity of the SAA1, but not the SAA2, promoter such that readout from the former became equivalent to that from the latter. A putative glucocorticoid response element (GRE) is present (between residues -208 and -194) only in the SAA1 gene; a similar sequence in the corresponding region of the SAA2 gene is disrupted by a nine-residue insertion. The SAA1 GRE was shown to be functionally active and the SAA2 disrupted GRE was shown to be functionally inactive in experiments using reporter constructs carrying SAA1 and SAA2 promoters that had been modified by site-specific mutagenesis. Quantitative analysis of transcript-specific RT-PCR products, derived from SAA1 and SAA2 mRNAs after treatment of HepG2 cells with cytokines in the presence or absence of dexamethasone, confirmed that the endogenous SAA1 gene has a cytokine-driven transcriptional disadvantage that is superseded by a marginal transcriptional advantage when glucocorticoids are present.

Determination of probability distribution of diplotype configuration (diplotype distribution) for each subject from genotypic data using the EM algorithm

Haplotype analysis is important for mapping traits. Recently, methods for estimating haplotype frequencies from genotypes of unrelated individuals based on the expectation-maximization (EM) algorithm have been developed. Our program estimates haplotype frequencies in the population and determines the posterior probability distribution of diplotype configuration (diplotype distribution) for each subject based on the estimated haplotype frequencies. Samples from three ethnic groups for the smoothelin gene (SMTN) and those from three Japanese groups for serum amyloid A genes (SAA@) were analyzed. The estimated diplotype distribution for each individual was concentrated, in most cases, in a single diplotype configuration. The diplotype configuration thus determined was the same as that determined in in vitro experiments, with one exception. Thus, the diplotype configurations determined using the estimated haplotype frequencies from unrelated individuals are reliable. Using this method, the risk of a subject developing a phenotype may be estimated from the diplotype distribution when the phenotype is associated with diplotype configurations.

Channel formation by serum amyloid A: a potential mechanism for amyloid pathogenesis and host defense

Serum amyloid A (SAA) is a family of closely related apolipoproteins associated with high density lipoprotein (HDL). Subclasses of SAA isoforms are differentially expressed constitutively and during inflammation. During states of infection or inflammation, levels of HDL bound, acute phase isoforms of SAA rise as much as 1000-fold in the serum, suggesting that it might play a role in host defense. Following recurrent or chronic inflammation, an N-terminal peptide fragment of SAA known as amyloid A (AA) assembles into fibrils causing extensive damage to spleen, liver, and kidney, and rapidly progressing to death. In the present paper, we report the novel finding that a recombinant acute phase isoform variant of human SAA 1.1 (SAAp) readily forms ion-channels in planar lipid bilayer membranes at physiologic concentrations. These channels are voltage-independent, poorly selective, and are relatively long-lived This type of channel would place a severe metabolic strain on various kinds of cells. Expression of human SAA 1.1 in bacteria induces lysis of bacterial cells, while expression of the constitutive isoform (human SAA4) does not. Secondary structural analysis of the SAA isoforms in dicates a strong hydrophobicity of the N-terminal of the acute phase isoform relative to the constitutive SAA4 isoform, which may be responsible for the bactericidal activity of the former, in keeping with the notion that SAA 1 targets cell membranes and forms channels in them. Channel formation may thus be related to a host defense role of acute phase SAA isoforms and may also be the mechanism of end organ damage in AA and other amyloidoses.

Microarray analysis of gene expression changes in mouse liver induced by peroxisome proliferator- activated receptor alpha agonists

We used a microarray technique to investigate changes of gene expression in liver induced by two peroxisome proliferator-activated receptor alpha (PPARalpha) agonists, a strong PPARalpha agonist, Wy-14,643, and a marketed fibrate drug, fenofibrate. The purposes of this work are: 1) to examine whether or not gene expression is altered in different ways by these two PPARalpha agonists and 2) to find genes whose expression has not been previously reported to be affected by PPARalpha agonists. Mice were treated orally with 100 mg/kg fenofibrate, or 30 mg/kg or 100 mg/kg Wy-14,643, and the liver was collected on Day 2 or 3. mRNA was extraction from liver, and subjected to microarray analysis. Previously reported induction or reduction of gene expression, e.g. genes involved in beta-oxidation and lipid metabolism, was confirmed in our study. Scatter plot analysis indicated that the changes of gene expression pattern induced by fenofibrate and Wy-14,643 were almost identical. However, expression levels of metallothionein 1 and 2 mRNAs were different: no change of hepatic metallothionein 1 and 2 mRNA expression was induced by 100 mg/kg fenofibrate on Day 2 or 3, while 30 mg/kg Wy-14,643 administration increased expression of both genes by 1.8-fold on Day 3. In addition to previously reported gene expression changes by PPARalpha agonists, we found expression changes of other genes, including cis-retinol/3alpha-hydroxysterol short chain dehydrogenase, vanin-1, RecA-like protein, and serum amyloid A (SAA) 2. Among them, the change of SAA2 mRNA level was noteworthy; it showed a decrease to as little as one-seventh. Seven-day fenofibrate pre-treatment of mice completely inhibited the acute-phase elevation of plasma SAA concentration triggered by acetaminophen challenge. This finding suggests that fenofibrate treatment may reduce plasma SAA concentration in patients with secondary amyloidosis.