A new method for determination of alpha-1-antitrypsin phenotypes using isoelectric focusing on polyacrylamide gel slabs

Living with the enemy: from protein-misfolding pathologies we know, to those we want to know

Conformational diseases are caused by the aggregation of misfolded proteins. The risk for such pathologies develops years before clinical symptoms appear, and is higher in people with alpha-1 antitrypsin (AAT) polymorphisms. Thousands of people with alpha-1 antitrypsin deficiency (AATD) are underdiagnosed. Enemy-aggregating proteins may reside in these underdiagnosed AATD patients for many years before a pathology for AATD fully develops. In this perspective review, we hypothesize that the AAT protein could exert a new and previously unconsidered biological effect as an endogenous metal ion chelator that plays a significant role in essential metal ion homeostasis. In this respect, AAT polymorphism may cause an imbalance of metal ions, which could be correlated with the aggregation of amylin, tau, amyloid beta, and alpha synuclein proteins in type 2 diabetes mellitus (T2DM), Alzheimer's and Parkinson's diseases, respectively.

Production of α2,6-sialylated and non-fucosylated recombinant alpha-1-antitrypsin in CHO cells

Alpha-1-antitrypsin (A1AT) is an abundant serum inhibitor of serine proteases. A1AT deficiency is a common genetic disorder which is currently treated with augmentation therapies. These treatments involve weekly injections of patients with purified plasma-derived A1AT. Such therapies can be extremely expensive and rely on plasma donors. Hence, large-scale production of recombinant A1AT (rA1AT) could greatly benefit these patients, as it could decrease the cost of treatments, reduce biosafety concerns and ensure quantitative and qualitative controls of the protein. In this report, we sought to produce α2,6-sialylated rA1AT with our cumate-inducible stable CHO pool expression system. Our different CHO pools could reach volumetric productivities of 1,2 g/L. The human α2,6-sialyltransferase was stably expressed in these cells in order to mimic elevated α2,6-sialylation levels of native A1AT protein. Sialylation of the recombinant protein was stable over the duration of the fed-batch production phase and was higher in a pool where cells were sorted and enriched by FACS based on cell-surface α2,6-sialylation. Addition of ManNAc to the cell culture media during production enhanced both α2,3 and α2,6 A1AT sialylation levels whereas addition of 2F-peracetylfucose potently inhibited fucosylation of the protein. Finally, we demonstrated that rA1AT proteins exhibited human neutrophil elastase inhibitory activities similar to the commercial human plasma-derived A1AT.

Hepatocellular Carcinoma with Intracytoplasmic Hyaline Globules

A case of hepatocellular carcinoma with intracytoplasmic hyaline globules is reported. By serological, histochemical, immunofluorescent and electron microscopic studies the authors maintain that in this case intracytoplasmic hyaline globules represent lysosomal structures. According to Von Ardenne's theory, these lysosomal globules appear related to neoplastic cells necrosis.

Deficiency Mutations of Alpha-1 Antitrypsin. Effects on Folding, Function, and Polymerization

Misfolding, polymerization, and defective secretion of functional alpha-1 antitrypsin underlies the predisposition to severe liver and lung disease in alpha-1 antitrypsin deficiency. We have identified a novel (Ala336Pro, Baghdad) deficiency variant and characterized it relative to the wild-type (M) and Glu342Lys (Z) alleles. The index case is a homozygous individual of consanguineous parentage, with levels of circulating alpha-1 antitrypsin in the moderate deficiency range, but is a biochemical phenotype that could not be classified by standard methods. The majority of the protein was present as functionally inactive polymer, and the remaining monomer was 37% active relative to the wild-type protein. These factors combined indicate an 85 to 95% functional deficiency, similar to that seen with ZZ homozygotes. Biochemical, biophysical, and computational studies further defined the molecular basis of this deficiency. These studies demonstrated that native Ala336Pro alpha-1 antitrypsin could populate the polymerogenic intermediate-and therefore polymerize-more readily than either wild-type alpha-1 antitrypsin or the Z variant. In contrast, folding was far less impaired in Ala336Pro alpha-1 antitrypsin than in the Z variant. The data are consistent with a disparate contribution by the "breach" region and "shutter" region of strand 5A to folding and polymerization mechanisms. Moreover, the findings demonstrate that, in these variants, folding efficiency does not correlate directly with the tendency to polymerize in vitro or in vivo. They therefore differentiate generalized misfolding from polymerization tendencies in missense variants of alpha-1 antitrypsin. Clinically, they further support the need to quantify loss-of-function in alpha-1 antitrypsin deficiency to individualize patient care.

Role of alpha-1 antitrypsin in human health and disease

Alpha-1 antitrypsin (AAT) deficiency is an under-recognized hereditary disorder associated with the premature onset of chronic obstructive pulmonary disease, liver cirrhosis in children and adults, and less frequently, relapsing panniculitis, systemic vasculitis and other inflammatory, autoimmune and neoplastic diseases. Severe AAT deficiency mainly affects Caucasian individuals and has its highest prevalence (1 : 2000-1 : 5000 individuals) in Northern, Western and Central Europe. In the USA and Canada, the prevalence is 1: 5000-10 000. Prevalence is five times lower in Latin American countries and is rare or nonexistent in African and Asian individuals. The key to successful diagnosis is by measuring serum AAT, followed by the determination of the phenotype or genotype if low concentrations are found. Case detection allows implementation of genetic counselling and, in selected cases, the application of augmentation therapy. Over the past decade, it has been demonstrated that AAT is a broad-spectrum anti-inflammatory, immunomodulatory, anti-infective and tissue-repair molecule. These new capacities are promoting an increasing number of clinical studies, new pharmacological formulations, new patent applications and the search for alternative sources of AAT (including transgenic and recombinant AAT) to meet the expected demand for treating a large number of diseases, inside and outside the context of AAT deficiency.

Isoelectric focusing of horse acidic prealbumins on thin-layer polyacrylamide gels

The paper describes a technique of thin-layer polyacrylamide gel isolectric focusing of horse serum, within a pH range of 4.0--6.0, which permits the improved resolution of the acidic prealbumin protein bands. The increased heterogeneity of the Pr prealbumin antiprotease allele products apparent using this technique is described and discussed in detail, and the potential use of the technique in routine Pr phenotyping is considered.

Evaluation of a new Sebia isoelectrofocusing kit for alpha 1-antitrypsin phenotyping with the Hydrasys System

BACKGROUND

Laboratory evaluation of alpha 1-antitrypsin (A1AT) deficiency is generally performed by determination of A1AT concentrations and identification of specific allelic variants by phenotyping. For this purpose, we evaluated a new Hydragel 18 A1AT Isofocusing kit on the semi-automatic Hydrasys System (Sebia) for the determination of A1AT phenotypes by isoelectrofocusing on ready-to-use agarose gels with specific immunological detection.

METHODS

Serum samples from 66 patients were analysed with this new kit in comparison with the conventional and manually performed isoelectrofocusing method on polyacrylamide gels with Coomassie Blue staining.

RESULTS

A1AT phenotypes showed comparable iso-electrofocusing patterns in both systems. The good within-gel reproducibility of this kit was demonstrated using two normal serum samples (M1 and M1M2 phenotypes) and six pathological serum samples with different phenotypes (MS, SS, SZ, MZ, ZZ). A sensitivity study was undertaken by performing serial dilutions on a serum with a ZZ phenotype containing 0.27 g/L A1AT. The detection limit was 0.050 g/L.

CONCLUSIONS

This new method is highly specific, rapid and simple to perform. It improves identification of not only the most common but also various rare A1AT phenotypes. It appears to be suitable for routine analysis and screening applications in a clinical laboratory setting.

Rapid and inexpensive detection of alpha1-antitrypsin deficiency-related alleles S and Z by a real-time polymerase chain reaction suitable for a large-scale population-based screening

alpha(1)-Antitrypsin (AAT) deficiency is one of the most common genetic disorders in Caucasians, leading to early onset pulmonary emphysema and/or liver disorders. Accumulating data suggest that AAT deficiency is commonly under-recognized or misdiagnosed by physicians. The need for a rapid, timesaving, and relatively inexpensive but reliable detection method for the two most common deficiency alleles was developed using real-time polymerase chain reaction (PCR) genotyping. We designed and validated a 5'-nuclease assay for typing of the PI*S and PI*Z alleles using dual-labeled target-specific fluorescent probes. As a reference method, we used restriction fragment length polymorphism. The real-time PCR method was tested on a large, cross-sectional epidemiological trial. Overall, we genotyped about 1200 samples and found a very good concordance with AAT serum levels and restriction fragment length polymorphism results. In addition, external interlaboratory validation confirmed the accuracy of the real-time PCR method. In our experience, the real-time qualitative PCR using 5'-nuclease assay is suitable as a genetic test for AAT deficiency. This method offers an acceptable balance between reliability and expenses. It seems appropriate for both population-based screening and clinical diagnosis of the deficiency.

[Alpha1-antitrypsin deficiency: situation in Spain and development of a screening program]

Studies undertaken in Spain indicate that 9% of the general population aged between 40 and 70 years is affected by chronic obstructive pulmonary disease (COPD). Although tobacco smoke is the causative factor in more than 90% of cases, it is estimated that only 10% to 20% of smokers develop COPD. This may be explained by the existence of genetic or environmental factors that modulate the toxic effects of tobacco. The best known genetic factor is alpha1-antitrypsin deficiency, which is associated with an increased risk of developing pulmonary emphysema in smokers. The most recent guidelines from both the World Health Organization and the American Thoracic Society/European Respiratory Society recommend the establishment of screening programs for the detection of alpha1-antitrypsin deficiency in patients with COPD. This strategy is crucial in Spain, where the disease is under diagnosed, mainly due to a low index of suspicion among doctors.

Alpha1-antitrypsin and neutrophil elastase imbalance and lung cancer risk

OBJECTIVE

Imbalance between alpha(1)-antitrypsin and neutrophil elastase is an underlying cause of lung tissue damage that may create a favorable host environment for carcinogenesis. We conducted a case-control study to investigate whether genetic variations indicative of alpha(1)-antitrypsin deficiency (A1ATD) or an excess of neutrophil elastase modify lung cancer risk

DESIGN

The case patients were 305 consecutively identified primary lung cancer patients, and the control subjects were 338 community residents. Protease inhibitor-1 (PI1), encoding alpha(1)-antitrypsin, was typed by an isoelectric focusing assay. Neutrophil elastase-2 (ELA2), encoding neutrophil elastase, was typed by two single-nucleotide polymorphism sites. Multivariable logistic regression models tested the independent and interactive effects of PI1, ELA2, tobacco smoke exposure, COPD, and family history of lung cancer

RESULTS

Sex and ethnicity were comparable between case patients and control subjects, but case patients were more likely to be smokers, and to have a history of COPD, environmental tobacco smoke exposure, and a positive family history of lung cancer. Haplotype analysis indicated an overall strong association between the two ELA2 markers and lung cancer risk. Our best-fitting model showed significant and independent effects of the PI1-deficient allele (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.4 to 3.0) and the ELA2 T-G haplotype (OR, 4.1; 95% CI, 1.9 to 8.9) on lung cancer risk, and an increased risk (OR, 2.6; 95% CI, 2.4 to 2.8) for individuals carrying both a PI1-deficient allele and a G-G haplotype

CONCLUSIONS

Genotypes indicative of A1ATD and/or an excess of neutrophil elastase are significantly associated with lung cancer risk. Our findings may provide opportunities to better understand the mechanisms of lung cancer development and risk reduction.

Alpha 1-antitrypsin deficiency in Europe: geographical distribution of Pi types S and Z

alpha 1-Antitrypsin (AT) is the principal serum inhibitor of proteolytic enzymes such as neutrophil elastase. AT can exist as over 90 different genetically determined variants known as the Pi system; the three most important variants are type M (90% of population) and types S and Z, two of the commoner abnormal variants. Homozygotes of type Z have a severe reduction in the serum AT concentration and may develop pulmonary emphysema or hepatic cirrhosis. Heterozygotes of type SZ have a less severe reduction in serum AT concentration and the association with clinical disease is less clear. The S and Z variants are found mainly among those of European stock. The gene frequency for Pi type Z is highest on the north-western seaboard of the continent and the mutation seems likely to have arisen in southern Scandinavia. The distribution of type S is quite different; the gene frequency is highest in the Iberian peninsula and the mutation is likely to have arisen in that region. A population survey for determining the number of type Z homozygotes in a given community is important for planning purposes now that AT replacement therapy is potentially available.

Subtyping of group-specific component and protease inhibitor by rapid isoelectric focusing on PhastSystem

A rapid method on PhastSystem was used to investigate the distribution of group-specific component (GC) and protease inhibitor (PI) subtypes and their gene frequencies from 190 unrelated healthy donors of the Han population in Beijing. Laboratory-made gels (pH 4.5-5.4 and pH 4.2-4.9) were used for analysis of GC and PI, respectively. Sample loading was 1.5 microliters. The separation and visualization time was 0.5 h in each. Gene frequencies were as follows: GC*1F = 0.4891, GC*1S = 0.2432, GC*2 = 0.2678; rare GC variants were discovered in seven cases. The results for PI were: PI*M1 = 0.7542, PI*M2 = 0.1808, PM*M3 = 0.0650. Good agreement between the observed and expected values in both GC and PI subtyping (for GC, sigma chi 2 = 1.4043, 0.7 < P < 0.8; for PI, sigma chi 2 = 1.1233, 0.7 < P < 0.8) was obtained.

Role of a distal enhancer containing a functional NF-kappa B-binding site in lipopolysaccharide-induced expression of a novel alpha 1-antitrypsin gene

alpha 1-Antitrypsin (alpha 1-AT) is one of the major proteinase inhibitors in serum. Its primary physiological function is to inhibit neutrophil elastase activity in lung, but it also inhibits other serine proteases including trypsin, chymotrypsin, thrombin, and cathepsin. We have previously reported a novel alpha 1-AT, S-2 isoform, from rabbit that is induced up to 100-fold in the liver during acute inflammatory condition (Ray, B. K., Gao, X., and Ray, A. (1994) J. Biol. Chem. 269, 22080-22086). Here, we present evidence that the expression of this alpha 1-AT S-2 gene is also induced in lipopolysaccharide (LPS)-treated peripheral blood monocytes. From the cloned genomic DNA, we have identified a distal LPS-responsive enhancer located between -2438 and -1990 base pairs upstream of the transcription start site. In vitro DNA-binding studies demonstrated an interaction of an LPS-inducible NF-kappa B-like nuclear factor with a kappa B-element present in this enhancer region. Antibodies against p65 and p50 subunits of NF-kappa B supershifted the DNA-protein complex. A mutation of the NF-kappa B-binding element virtually abolished the LPS-responsive induction of the chimeric promoter in monocytic cells. Furthermore, overexpression of NF-kappa B induced the wild-type promoter activity. Taken together, these results demonstrated that during LPS-mediated inflammation, NF-kappa B/Rel family of transcription factors play a crucial role in the transcriptional induction of the inflammation responsive alpha 1-AT gene.

Reliable phenotyping of alpha-1-antitrypsin by hybrid isoelectric focusing in an ultranarrow immobilized pH gradient

Genetically determined phenotypes of the highly polymorphic human alpha 1-antitrypsin were examined by hybrid isoelectric focusing in a narrow immobilized pH gradient. The chosen pH range from 4.45 to 4.75 was useful for identification and classification of the common PI M subtypes and a number of PI variants in the microheterogeneous regions of m6, m7, and m8. A high degree of resolution and an improved sharpness of PI bands was achieved with this excellent technique. It allowed the distinction of a new PI M variant, which has been designated M8, or Mingolstadt, according to the PI nomenclature. The pI difference of this mutant to the slightly cathodically located subtype M3 is approximately 0.001 pH unit. In addition, some common as well as rare phenotypes are presented.

Plasma levels of elastase-specific fibrinopeptides correlate with proteinase inhibitor phenotype. Evidence for increased elastase activity in subjects with homozygous and heterozygous deficiency of alpha 1-proteinase inhibitor

There is indirect evidence that unopposed human neutrophil elastase (HNE) is responsible for emphysema in patients with alpha 1-proteinase inhibitor (Pi) deficiency. To directly explore this possibility, we developed an assay for fibrinopeptide A alpha 1-21 and its degradation products and used it to measure HNE activity in 128 subjects of known Pi phenotype. The mean elastase-specific fibrinopeptide (ESF) level in 49 deficient PiZ individuals is significantly higher than that in 56 PiMZ heterozygotes (4.5 and 1.5 nM, respectively; P less than 0.01), while the mean ESF value in heterozygotes is significantly elevated over that in 23 normal PiM subjects (1.5 and 0.6 nM, respectively; P less than 0.01), consistent with increased HNE activity in those deficient in the major regulator of the enzyme. These results are not due to differences in smoking history because after correction for pack-years of smoking, ESF values in PiZ subjects are fourfold higher than those in PiMZ individuals (P = 0.005), while the ESF levels in heterozygotes are threefold higher than those in PiM subjects (P = 0.02). In addition, this analysis suggests that cigarette smoking and alpha 1-proteinase inhibitor deficiency have additive effects on ESF levels thereby explaining why PiZ and some PiMZ individuals are at especially high risk for the development of lung disease if they smoke. Finally, the observation that ESF levels in nonsmoking PiZ subjects are inversely related to the percent of predicted forced expiratory volume in 1 s (FEV 1%) provides direct support for the concept that unregulated HNE activity causes alveolar septal destruction in patients with alpha 1-proteinase inhibitor deficiency.

Family study of alpha 1-antitrypsin deficiency: effects of cigarette smoking, measured genotype, and their interaction on pulmonary function and biochemical traits

To gain insight into the variable expression of lung disease in alpha 1-antitrypsin (alpha 1AT) deficiency, five quantitative variables including forced expiratory volume at 1 sec (FEV1), forced expiratory flow rate between 25 and 75% of forced vital capacity (FEF25-75), total serum alpha 1AT, oxidized serum alpha 1AT, and total serum immunoglobulin E (IgE) were measured in alpha 1AT deficient individuals and their families. The effect of a known, measured genotype (the Pi type) was estimated for each quantitative trait; the influence of mode of case ascertainment on the measured genotype effect was also assessed. These analyses showed that total alpha 1AT levels are strongly influenced by Pi type; IgE levels are unaffected by Pi type; and FEV1, FEF25-75, and oxidized alpha 1AT are moderately influenced by Pi type. The effect of genotype-by-environment interaction between Pi type and pack-years of cigarette smoking on the five quantitative phenotypes was studied using an analysis of covariance. Significant Pi x pack-years interaction was evident for FEV1, but this effect is confounded in this data set with the Pi x age interaction. Probands who were ascertained because they had chronic obstructive pulmonary disease (COPD) do not demonstrate the significant Pi x pack-years interaction effect of the Pi x pack-years subjects ascertained for other reasons demonstrate. The effect of the Pi x pack-years interaction on FEV1 was no longer significant on a transformed scale, (FEVf12,) thus providing an additive scale for future data analysis. The increased sensitivity of Pi MZ individuals in our sample to cigarette smoking reduced the Pi x packs-years interaction effect on FEF25-75 to borderline significance. This investigation has provided an opportunity to incorporate both measured genotype and genotype-by-environment interaction analyses into the study of the variable expression of lung disease in Pi Z individuals.

PI polymorphism in Israel: report on six Jewish population groups

A total of 1148 Israeli Jews was typed for PI and divided by areas of origin into six groups: Eastern Europe (n = 236), Central Europe (n = 156), Rumania (n = 158), Bulgaria (n = 215), North Africa (n = 229), and Middle East (n = 154). Frequencies of PI*M1 (0.74-0.77) in Jews of European countries were higher than 0.68 in Jews of N. Africa and 0.62 in Jews of the Middle East. PI*M2 frequencies were correspondingly lower in European Jews: 0.11-0.14 vs 0.19 and 0.20 in non-European Jews. PI*M3 frequency range was 0.07-0.11 in European Jews and was highest in Middle Eastern Jews (0.17). PI*Z was found in one MZ individual. PI*S was low (less than 0.01) except in Sephardi Jews of Bulgaria and N. Africa (0.016 and 0.015). A rare variant, PI*Elemberg, was observed in five individuals from different countries of origin. The present results are in accord with those of a previous study on some Israeli Jewish groups and on some other Middle Eastern groups.

Characterization of the sequence of the normal alpha-1-antitrypsin M3 allele and function of the M3 protein

Alpha-1-antitrypsin (alpha 1AT), a highly pleomorphic 52 kD glycoprotein, functions chiefly as the major inhibitor of neutrophil elastase. Of the known alpha 1AT variants, greater than 95% in the U.S. Caucasian population are those of the "normal" M family, including M1(Ala213), M1(Val213), M2 and M3, with M3 the least common of the group. Quantification of the functional capacity of the M3 protein as an inhibitor of neutrophil elastase demonstrated a Kassociation for neutrophil elastase of 10.1 +/- 1.5 x 10(6) M-1 s-1, a value comparable to the common normal M1(Val213) alpha 1AT. To define the nucleotide sequence of the M3 gene, the five coding exons of the alpha 1AT gene of an M3 homozygote were amplified by the polymerase chain reaction and cloned into the plasmid vector pUC19. Sequence analysis demonstrated that the alpha 1AT M3 gene differs from the alpha 1AT M1(Val213) gene by a single base substitution (Glu376 GAA----Asp376 GAC) and from the alpha 1AT M2 gene by a single base substitution (His101 CAT----Arg101 CGT). To establish the consistency of the alpha 1AT M3 genotype among individuals identified by isoelectric focusing of serum to have the M3 phenotype, analysis of genomic DNA of 16 individuals by means of allele-specific amplification revealed that residues 101 and 376 were Arg and Asp, respectively, in all M3 alleles, while residue 101 was His in all M2 alleles and residue 376 was Glu in all M1 alleles.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-1-antitrypsin deficiency. High prevalence in the St. Louis area determined by direct population screening

Considerable attention has been focused upon alpha-1-antitrypsin deficiency because of the insights into the pathogenesis of human pulmonary emphysema that may derive from study of deficient subjects, and because of evolving therapeutic strategies that may slow the progression of lung disease in affected persons. We have applied an automated immunoassay for alpha-1-antitrypsin to plasma samples from 20,000 blood donors. Seven PI Z antitrypsin-deficient persons were identified and confirmed; this is more than twice the number predicted from previous estimates of the Z allele frequency in the St. Louis area. Five of the subjects were further evaluated. We anticipate that this assay, if utilized to screen large populations, could identify many alpha-1-antitrypsin-deficient persons for study of the natural history of lung and liver disease associated with the deficiency. These subjects would be potential candidates for early intervention strategies to prevent the development of lung disease. The surprisingly high prevalence of deficient persons indicates that direct screening is the best method for prevalence estimation of genetic disorders.

HLA-A, B antigens and alpha 1-antitrypsin phenotypes in nodal generalised osteoarthritis and erosive osteoarthritis

HLA-A, B and alpha 1-antitrypsin phenotypes were studied in 90 unrelated patients with established nodal generalised osteoarthritis (OA). Compared with standard reference populations, independently increased frequency of the HLA-A1B8 and MZ alpha 1-antitrypsin phenotypes were observed (27% v 11.5%, relative risk 2.79, and 12% v 3.6%, relative risk 3.73 respectively). These associations related to developed of nodal generalised OA rather than to severity as judged by the summated radiographic scores for hand OA. Ten patients had marked subchondral radiographic erosions and were further classified as erosive OA; these patients had an increased frequency of the MS alpha 1-antitrypsin phenotype (30% v 9%) and higher radiographic OA scores corrected for presence of erosions. This first report of two independent genetic markers in nodal generalised OA is of interest in relation to the increasingly recognised inflammatory component of the osteoarthritis process.

Parvalbumins for calibrating acidic isoelectric focusing gels

Partially purified fish and amphibian parvalbumins are compared to several proteins commonly used in commercial standard mixtures for calibrating isoelectric focusing gels. Parvalbumins are proffered as useful standards for acidic ranges on the basis of conformity to a set of five criteria.

Heterozygosity of alpha 1-antitrypsin: a health risk?

alpha 1-Antitrypsin is a serum glycoprotein synthesized in the liver. It consists of a single polypeptide chain with a molecular weight of about 52,000. The molecule exhibits great genetic diversity with multiple codominant alleles at a single autosomal locus. The majority of the population expresses the M allele. The Z allele, which is the result of a single amino acid substitution, results in levels of alpha 1-antitrypsin that are only 10 to 15% of normal when inherited in the homozygous state. Two main pathological consequences of this state are liver and lung disease. The homozygous S phenotype has also been associated with reduced alpha 1-antitrypsin levels and pathology. The homozygous Z phenotype has an incidence of about 1 in 1700 in certain European populations. People who are heterozygous for the S or Z allele usually have alpha 1-antitrypsin levels which are about 60% of normal. The combined frequency of these alleles in the population may reach 10 to 15%. This review examines the controversy as to whether these individuals are at increased risk for pathology due to their reduced alpha 1-antitrypsin levels.

Molecular basis of alpha-1-antitrypsin deficiency

Alpha-1-antitrypsin (A1AT) deficiency is an autosomal hereditary disorder associated with a major reduction in serum A1AT levels. Clinically, A1AT deficiency is associated with emphysema in adults and, less commonly, liver disease in neonates. A1AT is a 52-kDa, 394-amino acid, single-chain glycoprotein normally present in serum at 150 to 350 mg/dl. The A1AT gene, composed of seven exons dispersed over 12 kb of chromosomal segment 14q31-32.3, is expressed in hepatocytes and mononuclear phagocytes. The A1AT protein, a member of the class of protease inhibitor proteins known as serpins (serine protease inhibitors), is a globular molecule composed of nine alpha-helices and three beta-pleated sheets. The major function of A1AT is to inhibit neutrophil elastase; A1AT does so through an active site centered around Met358 contained within an external stressed loop on the surface of the molecule. A1AT is a highly pleomorphic protein with greater than 75 variants determined at the protein and/or gene level. These variants can be categorized into four groups according to their serum A1AT level and function: normal, deficient, dysfunctional, and absent. There are two important salt bridges within the A1AT molecule (Glu342-Lys290; Glu263-Lys387); a mutation in the A1AT gene causing disruption of either salt bridge causes distinct molecular pathology resulting in reduced serum A1AT levels. Clinically relevant variants can be distinguished by a combination of isoelectric focusing of serum, restriction fragment length analysis of genomic DNA, oligonucleotide probes, and direct sequencing of the variant A1AT genes.

Familial clustering of scleroderma spectrum disease

This is the second case report of familial scleroderma (systemic sclerosis) in South Carolina. The family includes two cases of scleroderma meeting American Rheumatism Association criteria, one of systemic sclerosis sine scleroderma, and two other cases of undifferentiated connective tissue disease with features of scleroderma spectrum disorders; there are also two cases of Raynaud's phenomenon (one associated with rheumatoid arthritis), for a total of seven affected relatives. Evidence of scleroderma spectrum disorders was sought in six siblings of the two co-index cases and in 23 of the 35 offspring. Laboratory studies included antinuclear antibody determinations and typing for the following genetic markers: HLA (A, B, C, DR), complotypes, Gm and Km allotypes, and alpha-1 antitrypsin phenotypes. No common genetic markers restricted to affected members of this family were found, and no environmental exposures were detected that could explain this familial clustering of cases. This report should, however, add to the slowly accumulating information on the genetic characteristics of families at unusually high risk for scleroderma spectrum disorders. Positive antinuclear antibody tests at a titer of 1/40 or higher were present in 57 percent of the first-degree relatives of the affected cases.

Characterization of a biotin-conjugated ovine prolactin ligand

Ovine prolactin was biotinylated with N-hydroxysuccinimidobiotin. Biotinylation was proportional to the molar ratio of reactants. Gel electrophoresis of the biotinylated derivative revealed little or no change in migration, but isoelectric focusing showed an acidic shift when compared to oPRL. Biotinylated ovine prolactin (B-oPRL) was detected by anti-oPRL antiserum and avidin-fluorescein-isothiocyanate (FITC) on protein blots. Competitive binding assays using 125I-B-oPRL and 125I-oPRL revealed: (a) similar dissociation constants and ID50 values for binding to anti-oPRL antibodies; (b) similar dissociation constants and maximum binding values for binding to liver membrane preparations; and (c) similar dissociation curves for displacement by several pituitary hormones. In contrast, binding of biotinylated oPRL to Nb2 node cells was reduced by approximately 70% and its bioreactivity was only 10% of that of oPRL. Our results indicate that biotinylation of oPRL does not alter its binding characteristics as measured by radioimmunoassay and radioreceptor assay using hepatic lactogenic receptors, but decreases its binding and bioreactivity when measured in Nb2 lymphoma cells. Assuming that N-hydroxysuccinimidobiotin interacts with reactive free amino groups of oPRL, our results suggest that these groups are essential for binding and bioreactivity of the molecule in the Nb2 lymphoma cell system.

The elastase inhibitors of swine serum: isolation and partial characterization of the beta 1-globulin inhibitor and its interaction with elastase

1. The principal elastase inhibitor of swine serum, a beta 1-globulin, has been isolated from serum by ammonium sulfate fractionation, DEAE-cellulose column chromatography and chromatofocusing. 2. The purified beta 1-globulin was homogeneous by immunoelectrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Multiple zones (isoinhibitors) were produced on anionic polyacrylamide gels. The mol. wt for the native, elastase-inactivated inhibitor and the beta 1-globulin-elastase complex were respectively, 65,467 and 60,000 and 79,667. The amino acid residue weight was 63,331. 4. The electrophoretic mobilities of the native inhibitor, elastase-inactivated inhibitor and the inhibitor-elastase complex were respectively, -3.4, -3.8 and -2.2 x 10(-5) cm2/V per sec, the isoelectric points were respectively, 4.78-5.28 (major pIs = 5.15, 5.35), 4.63-5.35 (major pI = 5.13) and 6.02-6.2 (major pI = 6.12). 5. The first order dissociation rate constant for the beta 1-globulin-elastase complex (two-fold molar excess of elastase at 37 degrees C) was 1.9 x 10(-3) per sec with complete dissociation in 40.4 min. The dissociation constant for the complex was 1.47 x 10(-7) M. One mol of elastase was bound per mol of the inhibitor. 6. The beta 1-globulin-elastase complex reacts with antibody to either protein moiety.

Tissue-specific expression of the human alpha 1-antitrypsin gene is controlled by multiple cis-regulatory elements

Human alpha 1-antitrypsin (AAT) is expressed in the liver, and a 318 bp fragment immediately flanking the CAP site of the gene was found to be sufficient to drive the expression of a reporter gene (CAT) specifically in hepatoma cells. The enhancing activity however, was orientation-dependent. The DNA fragment was separated into a distal region and a proximal region. A "core enhancer" sequence GTGGTTTC is present within the distal region and is capable of activity enhancement in both orientations when complemented by the proximal region in the sense orientation. The results strongly suggest that there are multiple cis-acting elements in the human AAT gene that confer cell specificity for its expression. Nuclear proteins prepared from the hepatoma cells bound specifically to the proximal region in a band-shifting assay that was resistant to competition by the globin promoter DNA. Foot-printing analysis showed a protected domain within the proximal region that contains a nearly perfect palindromic sequence TGGTTAATATTCACCA, which may be important in the regulation of AAT expression in the liver.

Isolation of tri-antennary enriched and tri-antennary depleted alpha-1-protease inhibitor

Alpha-1-protease inhibitor, (alpha-1-PI), the major inhibitor of serine proteases in human plasma, has three asparagine-linked carbohydrate chains located at positions 46, 83 and 247. The protein has a microheterogeneity which is seen on isoelectric focusing and which is a result of whether the various carbohydrate chains are in bi- or tri-antennary forms. Tri-antennary enriched forms of alpha-1-PI are associated with inflammation. By using a combination of three methods, reductive salting out, Sepharose-bound Concanavalin A affinity chromatography, and Sepharose-bound anhydrochymotrypsin, biologically active alpha-1-PI was obtained in tri-antennary enriched and tri-antennary depleted forms. These preparations should be useful for studies on the physiological role of the carbohydrate moiety in alpha-1-PI.

Tissue specific expression of the human alpha-1-antitrypsin gene in transgenic mice

Normal and mutant human alpha-1-antitrypsin genes were cloned from a PiMZ heterozygous individual. Nucleotide sequence comparison demonstrated a T to C transition in exon III and an G to A transition in exon V of the PiZ gene. A 14.4 kb DNA fragment containing the entire PiM gene plus 2 kb of 5' and 3' flanking genomic DNA sequences was introduced into the germ line of mice and five F0 transgenic lines were established. Transgenic F1 progeny from F0 parents exhibited high levels of human alpha-1-antitrypsin protein in their plasma. The human gene was expressed primarily in liver of the transgenic mice as it is in man. However, expression of the human alpha-1-antitrypsin gene was also observed in kidneys of the transgenic mice, which led to the observation that the endogenous mouse gene is also expressed in the kidney. These data indicate that cis-acting elements within or proximal to the human alpha-1-antitrypsin gene are able to direct its in vivo transcription with a high degree of tissue specificity.

Isolation and characterization of a galactose binding lectin with insulinomimetic activities. From the seeds of the bitter gourd Momordica charantia (Family Cucurbitaceae)

A galactose binding lectin was isolated from the seeds of the bitter gourd Momordica charantia by delipidation with petroleum ether, extraction with phosphate buffered saline, ammonium sulfate precipitation and affinity chromatography on lactogel. The lectin had a molecular weight of 124,000 and approximately 5% carbohydrate content. The molecular weights of the individual subunits were 37,000, 35,000 and 33,000. The lectin exhibited potent hemagglutinating activity. In addition, it demonstrated antilipolytic and lipogenic activities in isolated rat adipocytes although it did not possess intrinsic lipolytic activity. The antilipolytic activity was susceptible to destruction by heat, trypsin, chymotrypsin, glutathione and galactose, indicating that the integrity of the protein moiety, the disulfide linkages, and galactose, which is the sugar specifically bound by the lectin, all play an important role in interaction with the adipocyte leading to an expression of this insulin-like activity.

Chemical and biological characterization of the galactose binding lectins from Trichosanthes kirilowii root tubers

Three galactose binding isolectins have been isolated from Trichosanthes kirilowii root tubers. Two of the isolectins, TK-I and TK-II, are similar in many aspects including molecular weight, amino acid composition, NH2-terminal amino acid residue, blood group and carbohydrate specificities, immunodiffusion and immunoelectrophoretic behavior, hemagglutinating and insulinomimetic activities, and in possessing subunits with different molecular weights. Compared to TK-I and TK-II, lectin TK-III has a larger molecular weight, subunits with the same molecular weight, a single and distinctive NH2-terminal amino acid residue, a different isoelectric point and lower hemagglutinating activity. The three lectins share common antigenic determinants in their structures. beta-Linked terminal oligosaccharides containing D-galactose inhibit hemagglutination induced by the lectins with a higher potency than alpha-linked oligosaccharides. The lectins are non-mitogenic and did not inhibit the concanavalin-A induced mitogenic response of lymphocytes.

Detection of Pi Z phenotype individuals by alpha-1-antitrypsin (AAT) immunohistochemistry in paraffin-embedded liver tissue specimens

Immunostaining for alpha-1-antitrypsin (AAT) was applied on paraffin-embedded liver specimens from 38 Pi Z phenotype (27 Pi MZ; 9 Pi ZZ; 2 Pi SZ) individuals (33 adults, 5 newborns). Histological diagnoses included normal liver, various forms of chronic hepatitis, cirrhosis. A positive hepatocytic staining for AAT was revealed in all cases, whereas on PAS-D staining 5 cases were negative. Immunostaining revealed different patterns: type I: fine solid granules or coarse laminated globules filling the whole liver cell cytoplasm; type II: positive granules marginated towards the cell's periphery; type III: positive granules restricted to focal areas in the cytoplasm. Type I and III patterns were observed in all specimens. Association of type I and III with type II was seen in all Pi MZ and Pi SZ cases, but only in 3 of the 9 Pi ZZ specimens. To check the specificity of these staining patterns for the Z allele of AAT in adults and newborns, 180 further cases were investigated blindly by immunohistochemistry. Recognition of hepatocytic staining patterns type I, II and III allowed to reliably diagnose the Pi Z phenotype in 6 cases, whose heterozygous state was confirmed by independent serum phenotyping (5 Pi MZ, 1 Pi SZ). These results allow to conclude that: (1) immunohistochemistry is a reliable technique (superior to PAS-D staining) to identify Pi Z individuals (homo- and heterozygotes) on paraffin-embedded liver sections; (2) heterozygotes Pi MZ and Pi SZ cannot be differentiated without serum phenotyping; (3) immunohistochemistry is helpful in distinguishing between Z homozygotes from heterozygotes, but determination of AAT serum concentration is required to allow confident distinction without phenotyping. AAT immunohistochemistry thus allows to diagnose the Z allele of AAT when phenotyping procedures are not available or in retrospective studies on biopsy and autopsy material.

Neonatal hepatitis with obstructive jaundice in an SZ heterozygous alpha 1-antitrypsin-deficient boy and destructive lung disease in his SZ mother. A review of the literature

SZ-Alpha 1-antitrypsin deficiency, leading to severe transient neonatal cholestasis with mild hepatitis is rare. In our patient, intrahepatic bile duct hypoplasia was suspected. Since cholecystography and hepatic scintigraphy failed to reveal intrahepatic bile ducts, a diagnostic surgical liver biopsy was performed. Typical intrahepatocytic PAS-positive granules and a low serum alpha 1-antitrypsin concentration allowed a correct diagnosis of the SZ phenotype. The administration of an elementary diet quickly improved the clinical condition of our patient. Follow-up studies of this case and others will allow a better establishment of prognostic criteria and help in genetic counselling.

A modified double antibody sandwich enzyme-linked immunosorbent assay for measurement of alpha-1-antitrypsin in biologic fluids

Alpha-1-antitrypsin (alpha 1AT) is the major protease inhibitor in human serum, and plays an important role protecting tissues from potentially harmful enzymes released during inflammatory reactions. Proteolytic enzymes such as leukocyte elastase are usually released and inactivated locally at the site of inflammation, so there has been much recent interest in measuring local alpha 1AT concentrations in biologic fluids. In this study, we developed a modified double antibody sandwich enzyme-linked immunosorbent assay (ELISA) and used it to measure alpha 1AT concentrations in several biologic fluids. The assay was sensitive to as little as 20 ng/ml of alpha 1AT. Serum concentrations measured by the ELISA correlated well with levels determined by radial immunodiffusion (RID) and the ELISA was far more sensitive than RID. In synovial fluid, higher concentrations determined by the ELISA compared with RID probably reflect interference of diffusion of alpha 1AT in the RID gel by hyaluronic acid and protease-inhibitor complexes. Synovial fluid did not interfere with the detection of added alpha 1AT by ELISA, but it did reduce the amount detected by RID by about 30% in 2 fluids. In saliva, alpha 1AT concentrations of less than 1 microgram/ml were easily quantified. Bronchoalveolar lavage fluids have been extensively studied because of the important role of alpha 1AT in pulmonary inflammatory processes. We found concentrations of 1-3 micrograms/ml in most samples with our assay. These levels were comparable to those previously reported with assays that required up to 50-fold concentration of the fluid. Neither saliva nor bronchoalveolar fluid significantly interfered with detection by ELISA of added alpha 1AT. This modified double antibody sandwich ELISA may have broad applications for studies of the role of alpha 1AT in health and disease.

A population study of alpha-keto acid reductase

An electrophoretic survey of 509 individuals of Japanese, Mexican American, American Negro, Eskimo, Amerindian and Anglo-American origin failed to reveal genetically determined variation at the alpha-keto acid reductase locus by starch gel electrophoresis. Additional screening of 232 individuals by thin layer isoelectric focusing in polyacrylamide gels detected a single phenotype. Interspecific variation at the alpha-keto acid reductase locus is clearly resolved using either method. These results indicate that the alpha-keto acid reductase locus is monomorphic in most human population groups despite earlier results suggesting the existence of genetic polymorphism.

The diagnostic value of alpha 1-antitrypsin globules in liver cells as a morphological marker of alpha 1-antitrypsin deficiency

In order to determine the diagnostic value of alpha 1-antitrypsin (AAT) globules as a morphological marker of AAT-deficiency of the Pi-Z type, liver needle biopsies from a prospective series of 600 patients were stained with PAS after pretreatment with diastase and by indirect immunoperoxidase staining for AAT deposits. Serum AAT phenotypes of the patients were determined by means of isoelectric focusing. Thirty-two biopsies were from patients with the Pi-Z allele (31 MZ, 1 Z), and 568 biopsies from patients without the Pi-Z allele. AAT globules larger than 3 micron were found in 16 biopsies of which 15 were from patients with the Pi-Z allele (diagnostic specificity 0.94), whereas 20 of 26 biopsies with AAT globules larger than 1 micron were from Pi-Z patients (diagnostic specificity 0.77). Only 47% of the biopsies from patients with the Pi-Z allele contained AAT globules larger than 3 micron. Thus, although AAT globules larger than 3 micron are highly specific as a morphological marker of the Pi-Z allele, their rather infrequent occurrence in carriers of the Pi-Z allele indicates that all investigations concerning the correlation between AAT deficiency of the Pi-Z type and liver disease should be based on phenotyping of sera from all the patients.

Complete sequence of the cDNA for human alpha 1-antitrypsin and the gene for the S variant

A 1434 base pair human liver cDNA coding for the entire alpha 1-antitrypsin protein has been isolated and sequenced. Translation of the coding region into amino acids reveals a precursor molecule which contains a 24 amino acid signal peptide and 394 amino acids present in the mature polypeptide chain. The human gene for the S variant of alpha 1-antitrypsin has also been subcloned and sequenced. The gene is composed of 10226 nucleotide bases and is approximately equimolar for all 4 nucleotides. The gene contains four intervening sequences (introns) and 5' and 3' noncoding regions which are 54 and 79 nucleotides in length, respectively. A 5.3-kilobase intron exists in the 5' noncoding region and contains a 143 amino acid open reading frame, an Alu family sequence, and a pseudo transcription initiation region. No significant differences in base composition are seen between the introns and those regions corresponding to coding regions of the corresponding mRNA (exons). A sequence of 1951 nucleotides flanking the 5' end of the gene has also been determined and contains a "TATA" box sequence (TTAAA-TA) 21 nucleotides upstream from the proposed transcription start site. Comparison of the gene sequence with the cDNA sequence reveals a single base substitution (A----T), which results in a Glu----Val substitution at position 264 in the S variant protein. The position and size of introns, the overall base composition, and the codon preference for the alpha 1-anti-trypsin gene differ from those for the chicken ovalbumin gene even though the two proteins belong to a common protein family, as judged by amino acid sequence homology.