Alpha 1-antitrypsin: structure, function and molecular biology of the gene

Computational Tools to Assist in Analyzing Effects of the SERPINA1 Gene Variation on Alpha-1 Antitrypsin (AAT)

In the rapidly advancing field of bioinformatics, the development and application of computational tools to predict the effects of single nucleotide variants (SNVs) are shedding light on the molecular mechanisms underlying disorders. Also, they hold promise for guiding therapeutic interventions and personalized medicine strategies in the future. A comprehensive understanding of the impact of SNVs in the SERPINA1 gene on alpha-1 antitrypsin (AAT) protein structure and function requires integrating bioinformatic approaches. Here, we provide a guide for clinicians to navigate through the field of computational analyses which can be applied to describe a novel genetic variant. Predicting the clinical significance of SERPINA1 variation allows clinicians to tailor treatment options for individuals with alpha-1 antitrypsin deficiency (AATD) and related conditions, ultimately improving the patient's outcome and quality of life. This paper explores the various bioinformatic methodologies and cutting-edge approaches dedicated to the assessment of molecular variants of genes and their product proteins using SERPINA1 and AAT as an example.

Genetic characterization of potential venom resistance proteins in California ground squirrels ( Otospermophilus beecheyi ) using transcriptome analyses

Understanding the molecular basis of adaptations in coevolving species requires identifying the genes that underlie reciprocally selected phenotypes, such as those involved in venom in snakes and resistance to the venom in their prey. In this regard, California ground squirrels (CGS; Otospermophilus beecheyi) are eaten by northern Pacific rattlesnakes (Crotalus oreganus oreganus), but individual squirrels may still show substantial resistance to venom and survive bites. A recent study using proteomics identified venom interactive proteins (VIPs) in the blood serum of CGS. These VIPs represent possible resistance proteins, but the sequences of genes encoding them are unknown despite the value of such data to molecular studies of coevolution. To address this issue, we analyzed a de novo assembled transcriptome from CGS liver tissue-where many plasma proteins are synthesized-and other tissues from this species. We then examined VIP sequences in terms of three characteristics that identify them as possible resistance proteins: evidence for positive selection, high liver expression, and nonsynonymous variation across CGS populations. Based on these characteristics, we identified five VIPs (i.e., α-2-macroglobulin, α-1-antitrypsin-like protein GS55-LT, apolipoprotein A-II, hibernation-associated plasma protein HP-20, and hibernation-associated plasma protein HP-27) as the most likely candidates for resistance proteins among VIPs identified to date. Four of these proteins have been previously implicated in conferring resistance to the venom in mammals, validating our approach. When combined with the detailed information available for rattlesnake venom proteins, these results set the stage for future work focused on understanding coevolutionary interactions at the molecular level between these species.

Development of anti-inflammatory peptidomimetics based on the structure of human alpha1-antitrypsin

Human α1-antitrypsin (hAAT) has two distinguishing functions: anti-protease activity and regulation of the immune system. In the present study we hypothesized that those two protein functions are mediated by different structural domains on the hAAT surface. Indeed, such biologically active immunoregulatory sites (not associated with canonical anti-protease activity) on the surface of hAAT were identified by in silico methods. Several peptides were derived from those immunoregulatory sites. Four peptides exhibited impressive biological effects in pharmacological concentration ranges. Peptidomimetic (14) was developed, based on the structure of the most druggable and active peptide. The compound exhibited a potent anti-inflammatory activity in vitro and in vivo. Such a compound could be used as a basis for developing novel anti-inflammatory drug candidates and as a research tool for better understanding hAAT functions.

Protease-Specific Biomarkers to Analyse Protease Inhibitors for Emphysema Associated with Alpha 1-Antitrypsin Deficiency. An Overview of Current Approaches

As a known genetic cause of chronic obstructive pulmonary disease (COPD), alpha1-antitrypsin deficiency (AATD) can cause severe respiratory problems at a relatively young age. These problems are caused by decreased or absent levels of alpha1-antitrypsin (AAT), an antiprotease which is primarily functional in the respiratory system. If the levels of AAT fall below the protective threshold of 11 µM, the neutrophil-derived serine proteases neutrophil elastase (NE) and proteinase 3 (PR3), which are targets of AAT, are not sufficiently inhibited, resulting in excessive degradation of the lung parenchyma, increased inflammation, and increased susceptibility to infections. Because other therapies are still in the early phases of development, the only therapy currently available for AATD is AAT augmentation therapy. The controversy surrounding AAT augmentation therapy concerns its efficiency, as protection of lung function decline is not demonstrated, despite the treatment's proven significant effect on lung density change in the long term. In this review article, novel biomarkers of NE and PR3 activity and their use to assess the efficacy of AAT augmentation therapy are discussed. Furthermore, a series of seven synthetic NE and PR3 inhibitors that can be used to evaluate the specificity of the novel biomarkers, and with potential as new drugs, are discussed.

Application of directed evolution and back-to-consensus algorithms to human alpha1-antitrypsin leads to diminished anti-protease activity and augmented anti-inflammatory activities

Primarily known as an elastase inhibitor, human alpha1-antitrypsin also exerts anti-inflammatory and immunomodulatory effects, both in vitro and in vivo. While the anti-protease mechanism of alpha1-antitrypsin is attributed to a particular protein domain coined the reactive center loop, anti-inflammatory and immunomodulatory loci within the molecule remain to be identified. In the present study, directed evolution and back-to-consensus algorithms were applied to human alpha1-antitrypsin. Six unique functional candidate sites were identified on the surface of the molecule; in manipulating these sites by point mutations, a recombinant mutant form of alpha1-antitrypsin was produced, depicting a requirement for sites outside the reactive center loop as essential for protease inhibition, and displaying enhanced anti-inflammatory activities. Taken together, outcomes of the present study establish a potential use for directed evolution in advancing our understanding of site-specific protein functions, offering a platform for development of context- and disease-specific alpha1-antitrypsin-based therapeutics.

Elevated serum alpha-1 antitrypsin is a major component of GlycA-associated risk for future morbidity and mortality

Background

GlycA is a nuclear magnetic resonance (NMR) spectroscopy biomarker that predicts risk of disease from myriad causes. It is heterogeneous; arising from five circulating glycoproteins with dynamic concentrations: alpha-1 antitrypsin (AAT), alpha-1-acid glycoprotein (AGP), haptoglobin (HP), transferrin (TF), and alpha-1-antichymotrypsin (AACT). The contributions of each glycoprotein to the disease and mortality risks predicted by GlycA remain unknown.

Methods

We trained imputation models for AAT, AGP, HP, and TF from NMR metabolite measurements in 626 adults from a population cohort with matched NMR and immunoassay data. Levels of AAT, AGP, and HP were estimated in 11,861 adults from two population cohorts with eight years of follow-up, then each biomarker was tested for association with all common endpoints. Whole blood gene expression data was used to identify cellular processes associated with elevated AAT.

Results

Accurate imputation models were obtained for AAT, AGP, and HP but not for TF. While AGP had the strongest correlation with GlycA, our analysis revealed variation in imputed AAT levels was the most predictive of morbidity and mortality for the widest range of diseases over the eight year follow-up period, including heart failure (meta-analysis hazard ratio = 1.60 per standard deviation increase of AAT, P-value = 1×10⁻¹⁰), influenza and pneumonia (HR = 1.37, P = 6×10⁻¹⁰), and liver diseases (HR = 1.81, P = 1×10⁻⁶). Transcriptional analyses revealed association of elevated AAT with diverse inflammatory immune pathways.

Conclusions

This study clarifies the molecular underpinnings of the GlycA biomarker’s associated disease risk, and indicates a previously unrecognised association between elevated AAT and severe disease onset and mortality.

Intestinal permeability and inflammation mediate the association between nutrient density of complementary foods and biochemical measures of micronutrient status in young children: results from the MAL-ED study

BACKGROUND

Environmental enteric dysfunction (EED) is thought to increase the risk of micronutrient deficiencies, but few studies adjust for dietary intakes and systemic inflammation.

OBJECTIVE

We tested whether EED is associated with micronutrient deficiency risk independent of diet and systemic inflammation, and whether it mediates the relation between intake and micronutrient status.

METHODS

Using data from 1283 children in the MAL-ED (Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health) birth cohort we evaluated the risk of anemia, low retinol, zinc, and ferritin, and high transferrin receptor (TfR) at 15 mo. We characterized gut inflammation and permeability by myeloperoxidase (MPO), neopterin (NEO), and α-1-antitrypsin (AAT) concentrations from asymptomatic fecal samples averaged from 9 to 15 mo, and averaged the lactulose:mannitol ratio z-score (LMZ) at 9 and 15 mo. Nutrient intakes from complementary foods were quantified monthly from 9 to 15 mo and densities were averaged for analyses. α-1-Acid glycoprotein at 15 mo characterized systemic inflammation. Relations between variables were modeled using a Bayesian network.

RESULTS

A greater risk of anemia was associated with LMZ [1.15 (95% CI: 1.01, 1.31)] and MPO [1.16 (1.01, 1.34)]. A greater risk of low ferritin was associated with AAT [1.19 (1.03, 1.37)] and NEO [1.22 (1.04, 1.44)]. A greater risk of low retinol was associated with LMZ [1.24 (1.08, 1.45)]. However, MPO was associated with a lower risk of high transferrin receptor [0.86 (0.74, 0.98)], NEO with a lower risk of low retinol [0.75 (0.62, 0.89)], and AAT with a lower risk of low plasma zinc [0.83 (0.70, 0.99)]. Greater nutrient intake densities (vitamins A and B6, calcium, protein, and zinc) were negatively associated with EED. Inverse associations between nutrient densities and micronutrient deficiency largely disappeared after adjustment for EED, suggesting that EED mediates these associations.

CONCLUSIONS

EED is independently associated with an increased risk of low ferritin, low retinol, and anemia. Greater nutrient density from complementary foods may reduce EED, and the control of micronutrient deficiencies may require control of EED.

The Urinary Peptidome as a Noninvasive Biomarker Development Strategy for Prenatal Screening of Down's Syndrome

Prenatal screening for Down's syndrome based on maternal age, ultrasound measures, and maternal serum biomarkers is recommended worldwide, but the false-positive rate and poor diagnostic performance of these screening tests remain problematic. Genetic analysis of cell-free DNA in maternal blood has been developed as a new prenatal screening for Down's syndrome, but it has a number of limitations, including turnaround time and cost. Prenatal screening diagnostic innovation calls for new tests that are noninvasive, accurate, and affordable. We report original observations on potential peptide biomarkers in maternal urine for screening of fetal Down's syndrome. The peptidome of urine samples from 23 pregnant women carrying Down's syndrome fetuses and 30 pregnant women carrying fetuses with normal karyotype was fractionated by weak cation exchange magnetic beads and analyzed by MALDI-TOF mass spectrometry. Levels of six peptides (m/z 1022.1, 1032.1, 1099.5, 1155.9, 1306.6, and 2365.6) were significantly altered between the case and control groups after controlling for maternal and gestational age. A classification model was constructed based on these candidate peptides that could differentiate fetuses with Down's syndrome from controls with a sensitivity of 95.7%, a specificity of 70.0%, and an area under receiver operating characteristic curves of 0.909 (95% confidence interval, 0.835-0.984). Peptide peaks at m/z 1099.5 and 1155.9 were identified as the partial sequences of alpha-1-antitrypsin and heat shock protein beta-1, respectively. These new findings support the new idea that maternal urinary peptidome offers prospects for noninvasive biomarker discovery and development for the prenatal screening of fetal Down's syndrome.

Differential quantitative proteomics study of experimental Mannheimia haemolytica mastitis in sheep

Objective was the differential quantitative proteomics study of ovine mastitis induced by Mannheimia haemolytica; clinical, microbiological, cytological and histopathological methods were employed for confirmation and monitoring. Proteins were separated by two-dimensional gel electrophoresis (2-DE) for all samples and differentially abundant proteins were identified by mass spectrometry; comparisons were performed with pre- (blood, milk) and post- (milk of contralateral gland) inoculation findings. Animals developed mastitis, confirmed by isolation of challenge strain and increase of neutrophils in milk and by histopathological evidence. In blood plasma, 33 differentially abundant proteins (compared to findings before challenge) were identified: 6 with decrease, 13 with new appearance and 14 with varying abundance. In a post-challenge milk whey protein reference map, 65 proteins were identified; actin cytoplasmic-1, beta-lactoglobulin-1/B, cathelicidin-1 predominated. Further, 89 differentially abundant proteins (compared to findings before challenge) were identified: 18 with decrease, 53 with new appearance, 3 with increase and 15 with varying abundance; 15 proteins showed status changes in blood plasma and milk whey. Differential abundance from inoculated and contralateral glands revealed 74 proteins only from the inoculated gland. Most differentially abundant proteins in milk whey were involved in cell organisation and biogenesis (n = 17) or in inflammatory and defence response (n = 13). SIGNIFICANCE: The proteomes of blood and milk from ewes with experimental mastitis caused by Mannheimia haemolytica and the differential proteomics in sequential samples after challenge are presented for the first time. This is the first detailed proteomics study in M. haemolytica-associated mastitis in ewes. An experimental model fully simulating natural mastitis has been used. Use of experimentally induced mastitis minimised potential variations and allowed consistency of results. The study included evaluation of changes in blood plasma and milk whey. Protein patterns have been studied, indicating with great accuracy changes that had occurred as part of the disease process and development, during the acute phase of infection. Relevant protein-protein interactions were studied. The entirety of proteomics findings has suggested that affected ewes had mounted a defence response that had been regulated by many proteins (e.g., cathelicidins, haptoglobin, serum amyloid A) and through various pathways (e.g., acute phase response, binding and transporting significant ions and molecules); these were interdependent at various points. Potential biomarkers have been indicated for use in diagnostic assays of mastitis.

[α1-antitrypsin Pittsburg mutations: report of two cases in the same family]

目的

分析2例α1抗胰蛋白酶（α1-AT）Pittsburg突变患者的临床和实验室特点。

方法

采用凝固法或发色底物法分别检测凝血时间及凝血因子活性；比浊法测定血小板聚集功能；采用毛细管电泳法测定血清蛋白；PCR扩增目的DNA片段并测序检测突变。

结果

先证者，女，34岁，多次术后出血及黄体破裂出血；女儿，10岁，无出血表现。两例患者APTT、凝血酶时间均明显延长且正常人混和血浆1∶1不能纠正，凝血因子Ⅸ、Ⅹ、Ⅺ、Ⅻ活性明显降低，蛋白C、蛋白S活性均为0，1 U/ml凝血酶诱导的血小板聚集降低，4 U/ml凝血酶诱导的血小板聚集为48%；血清α1球蛋白电泳条带异常；DNA测序结果显示两例患者的α1-AT基因（NG_008290.1）均存在g.T17132G（p.Met358Arg）杂合突变。

结论

α1-AT Pittsburg突变患者表现出明显的凝血异常，临床出血表现有较大的差异性，黄体破裂出血可能是女性患者的一个明显特征。

Identification of serpins specific for activated protein C using a lysate-based screening assay

Activated protein C (APC) is a powerful anticoagulant enzyme that proteolytically inactivates the cofactors of the Xase and prothrombinase complexes, factors VIIIa and Va. A common mutation in factor V, fV_Leiden, confers resistance to APC leading to an increased risk of thrombosis in the normal population. However, when coinherited with haemophilia, fV_Leiden reduces bleeding severity, suggesting that inhibition of APC may be a useful strategy for treatment of haemophilia. We previously reported on serpins that were rationally designed for improved specificity for APC over other coagulation serine proteases. Based on structural differences in the substrate binding pockets to either side of the P1 Arg, we mutated the P2 and P1' residues to Lys. Although this approach achieved APC specificity, it resulted in a reduction in the rate of APC inhibition relative to the parent containing only the P1 Arg. Here we conduct site-specific random mutagenesis at the P2 and P1' positions to determine if improvements could be made in the rate of APC inhibition. In addition to our original Lys mutations, we found that Arg and Gln also confer specificity for APC. However, in all cases specificity for APC resulted in a reduction in inhibition rate.

Point Mutation of a Non-Elastase-Binding Site in Human α1-Antitrypsin Alters Its Anti-Inflammatory Properties

Introduction

Human α1-antitrypsin (hAAT) is a 394-amino acid long anti-inflammatory, neutrophil elastase inhibitor, which binds elastase via a sequence-specific molecular protrusion (reactive center loop, RCL; positions 357-366). hAAT formulations that lack protease inhibition were shown to maintain their anti-inflammatory activities, suggesting that some attributes of the molecule may reside in extra-RCL segments. Here, we compare the protease-inhibitory and anti-inflammatory profiles of an extra-RCL mutation (cys232pro) and two intra-RCL mutations (pro357cys, pro357ala), to naïve [wild-type (WT)] recombinant hAAT, in vitro, and in vivo.

Methods

His-tag recombinant point-mutated hAAT constructs were expressed in HEK-293F cells. Purified proteins were evaluated for elastase inhibition, and their anti-inflammatory activities were assessed using several cell-types: RAW264.7 cells, mouse bone marrow-derived macrophages, and primary peritoneal macrophages. The pharmacokinetics of the recombinant variants and their effect on LPS-induced peritonitis were determined in vivo.

Results

Compared to WT and to RCL-mutated hAAT variants, cys232pro exhibited superior anti-inflammatory activities, as well as a longer circulating half-life, despite all three mutated forms of hAAT lacking anti-elastase activity. TNFα expression and its proteolytic membranal shedding were differently affected by the variants; specifically, cys232pro and pro357cys altered supernatant and serum TNFα dynamics without suppressing transcription or shedding.

Conclusion

Our data suggest that the anti-inflammatory profile of hAAT extends beyond direct RCL regions. Such regions might be relevant for the elaboration of hAAT formulations, as well as hAAT-based drugs, with enhanced anti-inflammatory attributes.

Proteolytic Systems in Milk: Perspectives on the Evolutionary Function within the Mammary Gland and the Infant

Milk contains elements of numerous proteolytic systems (zymogens, active proteases, protease inhibitors and protease activators) produced in part from blood, in part by mammary epithelial cells and in part by immune cell secretion. Researchers have examined milk proteases for decades, as they can cause major defects in milk quality and cheese production. Most previous research has examined these proteases with the aim to eliminate or control their actions. However, our recent peptidomics research demonstrates that these milk proteases produce specific peptides in healthy milk and continue to function within the infant's gastrointestinal tract. These findings suggest that milk proteases have an evolutionary function in aiding the infant's digestion or releasing functional peptides. In other words, the mother provides the infant with not only dietary proteins but also the means to digest them. However, proteolysis in the milk is controlled by a balance of protease inhibitors and protease activators so that only a small portion of milk proteins are digested within the mammary gland. This regulation presents a question: If proteolysis is beneficial to the infant, what benefits are gained by preventing complete proteolysis through the presence of protease inhibitors? In addition to summarizing what is known about milk proteolytic systems, we explore possible evolutionary explanations for this proteolytic balance.

Surfactant-aided precipitation/on-pellet-digestion (SOD) procedure provides robust and rapid sample preparation for reproducible, accurate and sensitive LC/MS quantification of therapeutic protein in plasma and tissues

For targeted protein quantification by liquid chromatography mass spectrometry (LC/MS), an optimal approach for efficient, robust and hi-throughput sample preparation is critical, but often remains elusive. Here we describe a straightforward surfactant-aided-precipitation/on-pellet-digestion (SOD) strategy that provides effective sample cleanup and enables high and constant peptide yields in various matrices, allowing reproducible, accurate and sensitive protein quantification. This strategy was developed using quantification of monocolnocal antibody in tissues and plasma as the model system. Surfactant treatment before precipitation substantially increased peptide recovery and reproducibility from plasma/tissue, likely because surfactant permits extensive denaturation/reduction/alkylation of proteins and inactivation of endogenous protease inhibitors, and facilitates removal of matrix components. The subsequent precipitation procedure effectively eliminates the surfactant and nonprotein matrix components, and the thorough denaturation by both surfactant and precipitation enabled very rapid on-pellet-digestion (45 min at 37 °C) with high peptide recovery. The performance of SOD was systematically compared against in-solution-digestion, in-gel-digestion and filter-aided-sample-preparation (FASP) in plasma/tissues, and then examined in a full pharmacokinetic study in rats. SOD achieved the best peptide recovery (∼21.0-700% higher than the other three methods across various matrices), reproducibility (3.75-10.9%) and sensitivity (28-30 ng/g across plasma and tissue matrices), and its performance was independent of matrix types. Finally, in validation and pharmacokinetic studies in rats, SOD outperformed other methods and provided highly accurate and precise quantification in all plasma samples without using stable isotope labeled (SIL)-protein internal standard (I.S.). In summary, the SOD method has proven to be highly robust, efficient and rapid, making it readily adaptable to large-scale clinical and pharmaceutical quantification of biomarkers or biotherapeutics.

Sugars communicate through water: oriented glycans induce water structuring

Cells are coated with a glycocalyx-a layer of carbohydrate-containing biomolecules, such as glycoproteins. Although the structure and orientation of the cell-surface glycans are frequently regarded as being random, we have found, using α-1-acid glycoprotein and antitrypsin as model systems for surface glycans, that this is not the case. A glycoprotein monolayer was adsorbed onto hydrophilic and hydrophobic substrates. Surface-force measurements revealed that the orientation of the glycans with respect to the aqueous solution has a profound effect on the structure of vicinal water. The glycan antennae of the surface-adsorbed glycoproteins apparently impose an ordering on the water, resulting in a strong repulsive force over some tens of nanometers with superposed film-thickness transitions ranging from ≈0.7 to 1.8 nm. When the glycan orientation is modified by chemical means, this long-range repulsion disappears. These results may provide an explanation as to why the multiantennary structure is ubiquitous in glycoproteins. Although direct, specific interactions between glycans and other biomolecules are essential for their functionality, these results indicate that glycans' long-range structuring of water may also influence their ability to interact with biomolecules in their vicinity.

The design of a new truncated and engineered alpha1-antitrypsin based on theoretical studies: an antiprotease therapeutics for pulmonary diseases

Alpha 1- antitrypsin (α1AT) a 54 kDa glycoprotein is a protease inhibitor. In the absence of α1AT, elastase released by lung macrophages, was not inhibited and lead to elastin breakdown and pulmonary problems such as emphysema or COPD. α1AT has three site of N-glycosylation and a characteristic reactive central loop (RCL). As small-scale medicines are preferred for pulmonary drug delivery, in this study α1ATs (1, 2, 3, 4 and 5) were engineered and shortened from the N-terminal region. In order to investigate the effect of different mutations and the deletion of 46 amino acids theoretical studies were performed. Homology modeling was performed to generate the 3D structure of α1ATs. The 10 ns Molecular Dynamic (MD) simulations were carried out to refine the models. Results from MD and protein docking showed that α1AT2 has the highest binding affinity for neutrophil elastase, provided the basis for the experimental phase in which sequences from the five α1AT constructs were inserted into the expression vector pGAPZα and expressed in the yeast Pichia pastoris. Although, the α1AT2 construct has the highest inhibitory activity even more that the native construct (α1AT5), results indicated the presence of protease inhibitory function of all the proteins' construct against elastase.

High-throughput proteomic characterization of plasma rich in growth factors (PRGF-Endoret)-derived fibrin clot interactome

Plasma rich in growth factors (PRGF®-Endoret®) is an autologous technology that contains a set of proteins specifically addressed to wound healing and tissue regeneration. The scaffold formed by using this technology is a clot mainly composed of fibrin protein, forming a three-dimensional (3D) macroscopic network. This biomaterial is easily obtained by biotechnological means from blood and can be used in a range of situations to help wound healing and tissue regeneration. Although the main constituent of this clot is the fibrin scaffold, little is known about other proteins interacting in this clot that may act as adjuvants in the healing process. The aim of this study was to characterize the proteins enclosed by PRGF-Endoret scaffold, using a double-proteomic approach that combines 1D-SDS-PAGE approach followed by LC-MS/MS, and 2-DE followed by MALDI-TOF/TOF. The results presented here provide a description of the catalogue of key proteins in close contact with the fibrin scaffold. The obtained lists of proteins were grouped into families and networks according to gene ontology. Taken together, an enrichment of both proteins and protein families specifically involved in tissue regeneration and wound healing has been found.

Validation of free flow electrophoresis as a novel plasma and serum processing and fractionation method in biobanking

Free flow electrophoresis (FFE) is a fractionation method, based on isoelectric focusing (IEF). We validate the reproducibility of the method and show that it can be applied by biobanks in order to fractionate fluid biospecimens efficiently and reproducibly and to facilitate downstream proteomic applications. We also propose a simple method allowing researchers to assess the reproducibility of each FFE run.

Encapsulation of alpha-1 antitrypsin in PLGA nanoparticles: in vitro characterization as an effective aerosol formulation in pulmonary diseases

Background

Alpha 1- antitrypsin (α1AT) belongs to the superfamily of serpins and inhibits different proteases. α1AT protects the lung from cellular inflammatory enzymes. In the absence of α1AT, the degradation of lung tissue results to pulmonary complications. The pulmonary route is a potent noninvasive route for systemic and local delivery. The aerosolized α1AT not only affects locally its main site of action but also avoids remaining in circulation for a long period of time in peripheral blood. Poly (D, L lactide-co glycolide) (PLGA) is a biodegradable and biocompatible polymer approved for sustained controlled release of peptides and proteins. The aim of this work was to prepare a wide range of particle size as a carrier of protein-loaded nanoparticles to deposit in different parts of the respiratory system especially in the deep lung. Various lactide to glycolide ratio of the copolymer was used to obtain different release profile of the drug which covers extended and rapid drug release in one formulation.

Results

Nonaqueous and double emulsion techniques were applied for the synthesis of nanoparticles. Nanoparticles were characterized in terms of surface morphology, size distribution, powder X-ray diffraction (XRD), encapsulation efficiency, in vitro drug release, FTIR spectroscopy and differential scanning calorimetry (DSC). To evaluate the nanoparticles cytotoxicity, cell cytotoxicity test was carried out on the Cor L105 human epithelial lung cancer cell line.

Nanoparticles were spherical with an average size in the range of 100 nm to 1μ. The encapsulation efficiency was found to be higher when the double emulsion technique was applied. XRD and DSC results indicated that α1AT encapsulated in the nanoparticles existed in an amorphous or disordered-crystalline status in the polymer matrix. The lactic acid to glycolic acid ratio affects the release profile of α1AT. Hence, PLGA with a 50:50 ratios exhibited the ability to release %60 of the drug within 8, but the polymer with a ratio of 75:25 had a continuous and longer release profile. Cytotoxicity studies showed that nanoparticles do not affect cell growth and were not toxic to cells.

Conclusion

In summary, α1AT-loaded nanoparticles may be considered as a novel formulation for efficient treatment of many pulmonary diseases.

Digestion of Protein in Premature and Term Infants

Premature birth rates and premature infant morbidity remain discouragingly high. Improving nourishment for these infants is the key for accelerating their development and decreasing disease risk. Dietary protein is essential for growth and development of infants. Studies on protein nourishment for premature infants have focused on protein requirements for catch-up growth, nitrogen balance, and digestive protease concentrations and activities. However, little is known about the processes and products of protein digestion in the premature infant. This review briefly summarizes the protein requirements of term and preterm infants, and the protein content of milk from women delivering preterm and at term. An in-depth review is presented of the current knowledge of term and preterm infant dietary protein digestion, including human milk protease and anti-protease concentrations; neonatal intestinal pH, and enzyme activities and concentrations; and protein fermentation by intestinal bacteria. The advantages and disadvantages of incomplete protein digestion as well as factors that increase resistance to proteolysis of particular proteins are discussed. In order to better understand protein digestion in preterm and term infants, future studies should examine protein and peptide fragment products of digestion in saliva, gastric, intestinal and fecal samples, as well as the effects of the gut micro biome on protein degradation. The confluence of new mass spectrometry technology and new bioinformatics programs will now allow thorough identification of the array of peptides produced in the infant as they are digested.

Mapping biological to clinical phenotypes during the development (21 days) and resolution (21 days) of experimental gingivitis

AIM

To characterize and map temporal changes in the biological and clinical phenotype during a 21-day experimental gingivitis study.

MATERIALS AND METHODS

Experimental gingivitis was induced over 21 days in healthy human volunteers (n = 56), after which normal brushing was resumed (resolution phase). Gingival and plaque indices were assessed. Gingival crevicular fluid was collected from four paired test and contra-lateral control sites in each volunteer during induction (Days 0, 7, 14 and 21) and resolution (Days 28 and 42) of experimental gingivitis. Fluid volumes were measured and a single analyte was quantified from each site-specific, 30s sample. Data were evaluated by analysis of repeated measurements and paired sample tests.

RESULTS

Clinical indices and gingival crevicular fluid volumes at test sites increased from Day 0, peaking at Day 21 (test/control differences all p < 0.0001) and decreased back to control levels by Day 28. Levels of four inflammatory markers showed similar patterns, with significant differences between test and control apparent at Day 7 (substance P, cathepsin G, interleukin-1β, elastase: all p < 0.03) and peaking at Day 21 (all p < 0.002). Levels of α-1-antitrypsin showed no pattern.

CONCLUSIONS

Levels of substance P, cathepsin G, interleukin-1β and neutrophil elastase act as objective biomarkers of gingival inflammation induction and resolution that typically precede phenotypical changes.

Marasmius oreades agglutinin (MOA) is a chimerolectin with proteolytic activity

The Marasmius oreades mushroom lectin (MOA) is well known for its exquisite binding specificity for blood group B antigens. In addition to its N-terminal carbohydrate-binding domain, MOA possesses a C-terminal domain with unknown function, which structurally resembles hydrolytic enzymes. Here we show that MOA indeed has catalytic activity. It is a calcium-dependent cysteine protease resembling papain-like cysteine proteases, with Cys215 being the catalytic nucleophile. The possible importance of MOA's proteolytic activity for mushroom defense against pathogens is discussed.

Screening for new biomarkers for subcortical vascular dementia and Alzheimer's disease

Background

Novel biomarkers are important for identifying as well as differentiating subcortical vascular dementia (SVD) and Alzheimer's disease (AD) at an early stage in the disease process.

Methods

In two independent cohorts, a multiplex immunoassay was utilized to analyze 90 proteins in cerebrospinal fluid (CSF) samples from dementia patients and patients at risk of developing dementia (mild cognitive impairment).

Results

The levels of several CSF proteins were increased in SVD and its incipient state, and in moderate-to-severe AD compared with the control group. In contrast, some CSF proteins were altered in AD, but not in SVD. The levels of heart-type fatty acid binding protein (H-FABP) were consistently increased in all groups with dementia but only in some of their incipient states.

Conclusions

In summary, these results support the notion that SVD and AD are driven by different pathophysiological mechanisms reflected in the CSF protein profile and that H-FABP in CSF is a general marker of neurodegeneration.

Insulin-degrading enzyme is exported via an unconventional protein secretion pathway

Insulin-degrading enzyme (IDE) is a ubiquitously expressed zinc-metalloprotease that degrades several pathophysiologically significant extracellular substrates, including insulin and the amyloid β-protein (Aβ), and accumulating evidence suggests that IDE dysfunction may be operative in both type 2 diabetes mellitus and Alzheimer disease (AD). Although IDE is well known to be secreted by a variety of cell types, the underlying trafficking pathway(s) remain poorly understood. To address this topic, we investigated the effects of known inhibitors or stimulators of protein secretion on the secretion of IDE from murine hepatocytes and HeLa cells. IDE secretion was found to be unaffected by the classical secretion inhibitors brefeldin A (BFA), monensin, or nocodazole, treatments that readily inhibited the secretion of α1-antitrypsin (AAT) overexpressed in the same cells. Using a novel cell-based Aβ-degradation assay, we show further that IDE secretion was similarly unaffected by multiple stimulators of protein secretion, including glyburide and 3'-O-(4-benzoyl)benzoyl-ATP (Bz-ATP). The calcium ionophore, A23187, increased extracellular IDE activity, but only under conditions that also elicited cytotoxicity. Our results provide the first biochemical evidence that IDE export is not dependent upon the classical secretion pathway, thereby identifying IDE as a novel member of the select class of unconventionally secreted proteins. Further elucidation of the mechanisms underlying IDE secretion, which would be facilitated by the assays described herein, promises to uncover processes that might be defective in disease or manipulated for therapeutic benefit.

Identification of sperm forward motility-related proteins in human seminal plasma

Seminal plasma, an amorphous material that exists in semen, contains proteins related to sperm forward motility. Employing affinity chromatography with ConA beads and protein ultrafiltration, we isolated and concentrated proteins from heated human seminal plasma. Results of computer-assisted semen analyses (CASA) demonstrated that the forward motility index of bovine spermatozoa from the epididymal caput, incubated with proteins and theophylline, was significantly different from that of spermatozoa incubated with theophylline alone (P < 0.01). The electrophoreses revealed that the protein bands with high molecular weights in the gel of PAGE changed into low molecular weights in the gel of SDS-PAGE. Furthermore, proteins from a separated portion of the PAGE gel were still able to stimulate spermatozoa from the epididymal caput to gain forward motility. Two-dimensional (2D)-gel electrophoresis and mass spectrometry indicated that spots focused on the portion seemed, according to their amino acid sequences, to be like human alpha-1-antitrypsin and zinc-alpha-2-glycoprotein (ZAG) precursors. Western blot analysis showed the presence of these two proteins in seminal plasma. These proteins, related to the forward motility of spermatozoa in human seminal plasma, may play important roles during maturation of spermatozoa, from the epididymis through fertilization in the female reproductive tract.

Human kallikrein 4: enzymatic activity, inhibition, and degradation of extracellular matrix proteins

Human kallikrein 4 (hK4) is a member of the expanded family of human kallikreins, a group of 15 secreted proteases. While this protein has been associated with ovarian and prostate cancer prognosis, only limited functional information exists. Therefore, we have undertaken an investigation of its enzymatic properties regarding substrate preference, degradation of extracellular matrix proteins, and its inhibition by various inhibitors. We successfully expressed and purified active recombinant hK4 from supernatants of the Pichia pastoris expression system. This enzyme seems to cleave more efficiently after Arg compared to Lys at the P1 position and exhibits modest specificity for amino acids at positions P2 and P3. hK4 forms complexes with alpha1-antitrypsin, alpha2-antiplasmin and alpha2-macroglobulin. The protease mediates limited degradation of extracellular matrix proteins such as collagen I and IV, and more efficient degradation of the alpha-chain of fibrinogen. The cleavage of extracellular matrix proteins by hK4 suggests that this enzyme may play a role in tissue remodeling and cancer metastasis.

Alpha-1-antitrypsin is present in the specific granules of human eosinophilic granulocytes

Eosinophils may be found at sites of inflammation, for example in asthma, allergy and helminthic infestation, but their role in human inflammatory disease is unclear. In the present study, we investigated the presence of alpha-1-antitrypsin (AAT), a serine proteinase inhibitor, in human eosinophils. When lysates of highly purified eosinophils were subjected to Western blotting, with a chemiluminescent substrate, immunoreactive bands were seen. An ELISA was developed to measure the AAT content, which was found to be about 100 ng/5 x 106 eosinophils, about 50 ng/5 x 106 neutrophils, and about 25 ng/5 x 106 monocytes. Immunoelectron microscopy showed localization of AAT to the specific granules of eosinophils. During prolonged incubation of eosinophils, no significant increase in the total amount of AAT could be detected by ELISA. However, there was an increased level of AAT in the medium, in parallel with a decrease in the intracellular AAT content, suggesting release of preformed AAT. Apparent complex formation between iodinated elastase and AAT in eosinophil lysates provided evidence that the AAT is functionally active. On the basis of these findings it is suggested that by releasing AAT, eosinophils may, in a microenvironment, play a role in counteracting the tissue damage caused by serine proteinases released by neutrophils in inflammatory conditions.

Serpins identified as cell growth inhibitors in human plasma

We have identified a new factor, CFX, in human serum and plasma that inhibits the growth of cultured human and mouse cell lines. CFX was determined to be a negatively charged, hydrophobic glycoprotein, with a native molecular weight of 110-120 kDa and a minimal active subunit of 55 kDa. It is precipitated by 60% ammonium sulfate and is resistant to heat treatment at 100 degrees C for 30 min. CFX was purified from human plasma to a single band on a gel which retained the cell growth inhibitory activity. Amino acid sequence analysis of the CFX band revealed sequences from four human glycoproteins, alpha1-antichymotrypsin, C1-esterase inhibitor, alpha1-antitrypsin, and alpha2-antiplasmin, all members of the superfamily of serpins. Of the four, C1-esterase inhibitor was shown to be the most potent cell growth inhibitor. These results suggest that serpins may play a cell growth inhibitory role in vivo, in addition to their role as protease inhibitors.

Immunochemical and functional properties of biliary alpha-1-antitrypsin

Alpha-1-antitrypsin (AAT), the archetype of the serpin (serine proteinase inhibitor) superfamily, is synthesized by hepatocytes and excreted to some extent into bile. The role of intact biliary AAT in gallstone pathogenesis is unsettled, but its 36-residue C-terminal peptide was found to promote cholesterol crystallization in a bile model. The present study showed biliary AAT to have specific properties that differ from serum AAT regarding immunoreactivity, heat stability and antiproteolytical activity. Electrophoretical and immunochemical methods were used to characterize biliary AAT. The level of its inhibitory activity was determined spectrophotometrically. In 18 samples from common bile duct and 12 samples from gallbladder bile, AAT was found to be heat-stable and functionally inactive. Added to the untreated, temperature-inactivated or protease inhibitors containing bile, native AAT became functionally inactive, heat-stable and lost its immunoreactivity. In contrast, heat-inactivated AAT, native albumin, transferrin, alpha-1-antichymotrypsin and IgG were unaffected on being added to bile. AAT in human bile manifests specific biochemical properties, such as functional inactivity and heat stability, that may be consistent with a conformational transition of the serpin molecule induced by the hydrophobic environment, and which must be considered when evaluating its role in gallstone pathogenesis.

The isolation and partial characterization of alpha 1-proteinase inhibitor from the serum of the ostrich (Struthio camelus)

1. Native and cleaved alpha 1-proteinase inhibitor was purified from ostrich serum using Sepharose-blue dextran chromatography, ammonium sulfate precipitation and ion exchange chromatography on DEAE-Toyopearl 650 M at pH 8.8 and 6.5. Ostrich alpha 1-PI displayed M(r) values of 68,100 using gradient PAGE and 66,200 using Ferguson plots. Isoelectric focusing of ostrich alpha 1-PI in the pH range 3-10 revealed pI values of 4.84 and 4.91, and in the pH range 4-6 the characteristic microheterogeneity observed for mammalian alpha 1-PIs was displayed. The presence of sialic acid, hexoses and hexosamines was detected using chemical methods, but were found in much lower quantities as compared to alpha 1-PIs of other species. Western blot analysis demonstrated a positive reaction between the native and cleaved ostrich alpha 1-PIs and the antibodies to the ostrich alpha 1-PIs raised in rabbits. No cross-reactivity was demonstrated by Western blot analysis between human alpha 1-PI and antibodies to ostrich alpha 1-PI. The inhibitory effect of alpha 1-PI on elastase and chymotrypsin was also investigated.

Intraspecific variation in serum proteins of brown hare (Lepus europaeus Pallas, 1778)

1. Serum proteins of brown hare (Lepus europaeus Pallas, 1778) were studied by the use of 1D PAGE, 2D agarose-PAGE, immunoblotting, inhibitions of trypsin and chymotrypsin, and specific staining for esterase. 2. Some serum proteins were identified, and easily interpretable polymorphisms were found in transferrin alpha 1B glycoprotein, protease inhibitors ATC2, ATC3 and AT1, esterase ES1 and in an unidentified postalbumin PO. 3. On the basis of family studies the evidence was obtained that the variants observed in these polymorphic proteins are under genetic control by codominant alleles of autosomal loci.

Secondary structure changes stabilize the reactive-centre cleaved form of SERPINs. A study by 1H nuclear magnetic resonance and Fourier transform infrared spectroscopy

Proteinase inhibitor members of the SERPIN superfamily are characterized by the presence of a proteolytically sensitive reactive-site loop. Cleavage within this region results in a conformational transition from an unstable "stressed" native protein to a more stable "relaxed" cleaved molecule. In order to identify the principal molecular aspects of this transition, 1H nuclear magnetic resonance (n.m.r.) and FT-IR spectroscopy were applied to the study of four SERPINs. 1H n.m.r. spectra of approximately 20 high-field ring-current-shifted methyl signals exhibited slightly different chemical shifts in the native and cleaved forms of alpha 1-antitrypsin (alpha 1-AT), alpha 1-antichymotrypsin (alpha 1-ACT) and C1 inhibitor (C1-INH), but not ovalbumin, between 20 degrees C and 90 degrees C. Ring current calculations based on crystal co-ordinates for cleaved alpha 1-AT and alpha 1-ACT and native ovalbumin showed that these signals originate from highly localized interactions between different buried residues corresponding to alpha-helix and beta-sheet segments of the SERPIN fold. The small shift changes correspond to small relative conformational side-chain rearrangements of about 0.01 nm to 0.05 nm in the protein hydrophobic core, i.e. the tertiary structure interactions in the two forms of the SERPIN fold are well-preserved, and changes in this appear unimportant for the stabilization found after reactive centre cleavage. Fourier transform infrared (FT-IR) spectroscopic studies of the amide I band showed that the native and cleaved forms of alpha 1-AT, alpha 1-ACT and C1-INH contain 28% to 36% alpha-helix and 38% to 44% beta-sheet. Second derivative FT-IR spectra using H2O and 2H2O buffers revealed very large differences in the amide I band between the native and cleaved forms of alpha 1-AT, alpha 1-ACT and C1-INH, but not for ovalbumin. The alpha-helix band was most sensitive to 1H-2H exchange, while the beta-sheet bands were not, and greater amounts of antiparallel beta-sheet were detected in the cleaved form. 1H n.m.r. showed that polypeptide amide 1H-2H exchange was greater in the native forms of alpha 1-AT, alpha 1-ACT and C1-INH than in their cleaved forms, whereas for ovalbumin it was unchanged. The FT-IR and 1H-2H exchange data show that alterations in the secondary structure are central to the stabilization of the cleaved SERPIN structure.(ABSTRACT TRUNCATED AT 400 WORDS)

On the role of monocytes/macrophages in the pathogenesis of central nervous system lesions in hereditary cystatin C amyloid angiopathy

The pathogenesis of the deposition of a variant cystatin C as amyloid in hereditary cystatin C amyloid angiopathy (HCCAA) is not known. To address this question the synthesis and secretion of cystatin C in cultured monocytes from 9 carriers of the mutated cystatin C gene (5 symptomatic and 4 asymptomatic) was examined. The quantity of cystatin C in cells and supernatants was determined by the ELISA method, Western blots were done and selected samples immunostained for cystatin C. Monocytes from individuals carrying the gene defect synthesized cystatin C that was apparently not truncated, a form found in the cerebral amyloid deposits in HCCAA, but showed a distinctly lower rate of cystatin C synthesis than monocytes from healthy controls. The main difference was that the quantity of cystatin C was significantly lower in the supernatants in monocyte cultures from carriers of the gene defect than from healthy controls, possibly due to a partial block in its secretion. This abnormal processing of the cystatin C could explain the low cerebrospinal fluid levels of cystatin C in HCCAA and might be a part of the pathogenetic pathway of amyloid deposition. Furthermore it could, through a lower extracellular concentration of this inhibitor of cysteine proteinases, contribute to destruction of the amyloidotic blood vessels, leading to the most serious clinical manifestation in HCCAA, intracerebral hemorrhage.

Leukocyte-mediated inactivation of alpha 1-proteinase inhibitor is inhibited by amino analogues of alpha-tocopherol

Human leukocytes stimulated by opsonized zymosan increase their NADPH oxidase-catalysed reduction of molecular oxygen. This leads to enhanced formation of superoxyl radicals and subsequently hydrogen peroxide. The leukocyte enzyme myeloperoxidase generates the strong microbicidal oxidant hypochlorite from hydrogen peroxide and chloride anions. Hypochlorite inactivates serum alpha 1-proteinase inhibitor, a protein which protects host tissue from digestion by proteinases, that are also secreted by stimulated leukocytes. Micromolar concentrations of a water-soluble, quaternary ammonium analogue of alpha-tocopherol (vitamin E) (3,4-dihydro-6-hydroxy-N,N,N-2,5,7,8-heptamethyl-2H-1-benzopyran-2 -ethanaminium 4-methylbenzenesulfonate) and its tertiary amine derivative (3,4-dihydro-2- (2-dimethylaminoethyl)-2,5,7,8-tetramethyl-2H-1-benzopyran-6-ol hydrochloride) were able to protect alpha 1-proteinase inhibitor from inactivation by stimulated human leukocytes. The mechanism of action of the quaternary ammonium analogue was further investigated. Selective inhibition of hydrogen peroxide formation is assumed to be the reason for its protective effect. This compound rapidly reacts with superoxyl radicals, but not with hydrogen peroxide, and is only a weak hypochlorite scavenger. It neither impedes exocytosis of elastase, nor effectively inhibits NADPH oxidase or myeloperoxidase. In contrast, superoxide dismutase, which enhances hydrogen peroxide formation, cannot protect alpha 1-proteinase inhibitor from inactivation.

The molecular genetics of alpha 1 antitrypsin deficiency

The human serum protein alpha 1-antitrypsin is the major source of antiprotease activity found in the blood. The protein is synthesised primarily by liver cells but, to a lesser extent, by at least one other cell type. Expression of the gene has provided a paradigm for studies on transcriptional regulation in liver and of tissue-specific promoter activity. The pleiomorphic nature of the gene has given rise to a variety of alpha 1-antitrypsin variants some of which are clinically important. These abnormal variants may be poorly synthesised, rapidly degraded or inefficiently secreted; studies on the molecular mechanisms which underly these events are providing interesting insights into the general processes of protein transport and intracellular protein degradation.