Metal-dependent hydrolysis of myelin basic protein by IgGs from the sera of patients with multiple sclerosis

Homogeneous IgG fractions were obtained by chromatography of the sera of patients with multiple sclerosis (MS) on Protein G-Sepharose under conditions that remove non-specifically bound proteins. These IgGs contained several chelated metals, the relative amount of which decreases in the order: Fe>or=Ca>Cu>or=Zn>or=Mg>or=Mn>or=Pb>or=Co>or=Ni. In contrast to homogeneous IgGs of healthy individuals, Abs of MS patients effectively hydrolyzed human myelin basic protein (MBP). A minor metal-dependent fraction was obtained by chromatography of highly purified IgGs from MS patient on Chelex-100. This IgG fraction did not hydrolyze human MBP in the absence of Me(2+) ions but was activated after addition of Me(2+) ions: Mg(2+)>Mn(2+)>Cu(2+)>Ca(2+). Proteolytic activities of IgGs from other MS patients were also activated by other metal ions (Ni(2+), Fe(2+), Co(2+), Zn(2+), Pb(2+), and Co(2+)) and especially Ni(2+). Ni(2+)-activated IgGs were separated into distinct MBP-hydrolyzing fractions by chromatography on HiTraptrade mark Chelating Sepharose charged with Ni(2+). Detection of Mg(2+)-dependent proteolytic activity in the SDS-PAGE area corresponding only to IgG provided direct evidence that IgG from sera of MS patients possesses metal-dependent human MBP-hydrolyzing activity. Observed properties of MS abzymes distinguish them from other known mammalian metalloproteases and demonstrate their pronounced catalytic diversity. Metal-dependent IgGs from MS patients represent the first example of abzymes with metal-dependent proteolytic activity.

Lipid kinase activity of antibodies from milk of clinically healthy human mothers

We have shown recently that polyclonal human milk sIgA contains a subfraction of antibodies (Abs) tightly bound to unusual minor milk lipids containing sialic acid. Here, we show that a small subfraction of milk IgG is tightly bound to the similar or the same minor lipids. The ability of small fractions of sIgA and IgG from human milk to phosphorylate selectively two minor lipids in the presence of [gamma-(32)P]nucleoside triphosphates was shown here for the first time to be an intrinsic property of these antibodies. In contrast to known kinases, antibodies with lipid kinase activity can transfer phosphoryl group to lipids not only from ATP but also from other different nucleotides (dATP, GTP, dGTP, UTP, TTP) with comparable efficiencies (30-100%). To our knowledge, there are no examples of enzymes using orthophosphate as a substrate of phosphorylation reactions. An extremely unusual property of lipid kinase Abs is their high affinity for orthophosphate (K(m)=1.6-5.6 microM) and capability to phosphorylate minor lipids using [(32)P]orthophosphate as donor of phosphate group. The relative specific activity and affinity of abzymes for orthophosphate and ATP depend significantly on donor milk. However, the levels of Ab-dependent phosphorylation of lipids for all Abs in the case of ATP (100%) and orthophosphate (60-80%) as substrates are comparable. The first example of natural abzymes with synthetic activity was milk sIgA with protein kinase activity. Most probably, lipid kinase sIgA and IgG of human milk are the second example of Abs with synthetic activity.

IgG antibodies with peroxidase-like activity from the sera of healthy Wistar rats

Various catalytic antibodies or abzymes (Abzs) have been detected recently in the sera of patients and animals with many autoimmune diseases, where their presence is most probably associated with autoimmunization. Normal humans or animals usually do not contain Abzs. In contrast, polyclonal Abzs from healthy humans and animals have an intrinsic superoxide dismutase activity and catalyze formation of H(2)O(2) (Wentworth et al., 2000, Proc. Natl. Acad. Sci. USA; 2001, Science). Here, we present the first evidence showing that highly purified native IgGs from the sera of healthy Wistar rats interact with H(2)O(2) and possess peroxidase-like activity. Specific peroxidase activity of IgG preparations from the sera of 10 rats varied in the range 1.6-27% as compared with that for horseradish peroxidase (100%). Antioxidant enzymes such as superoxide dismutases, catalases, and glutathione peroxidases are known to represent critical defence mechanisms for preventing oxidative modifications of DNA, proteins, and lipids. Antioxidant peroxidase activity of Abzs can also play an important role in the protection of organisms from oxidative stress as well as in oxidation of toxic compounds.

Hydrolysis of myelin basic protein by IgM and IgA antibodies from the sera of patients with multiple sclerosis

BACKGROUND

The presence of abzymes (Abzs) in human sera is a specific feature of different autoimmune pathologies. We have shown that IgGs of patients with multiple sclerosis (MS) specifically hydrolyze human myelin basic protein (hMBP). However, the presence of hMBP-hydrolyzing MS IgMs and IgAs in patients with MS has not been studied.

MATERIAL/METHODS

Homogeneous IgM and IgA fractions were isolated from human sera by affinity chromatography on different adsorbents. The Ab-dependent hydrolysis of hMBP was analyzed using SDS-PAGE.

RESULTS

We present evidence showing that MS IgMs and IgAs (but not Abs from the sera of healthy individuals) catalyze the hydrolysis of hMBP. Specific enzymatic activities of IgMs and sIgAs from sera of any single patient were usually significantly higher than those of IgGs. Specific inhibitors of acidic and thiol proteases demonstrated a weak effect on proteolytic activity of IgGs and IgMs. However, specific inhibitors of serine proteases (AEBSF, PMSF, and benzamidine) significantly inhibited proteolytic activity. IgMs and IgAs hydrolyze specifically both human and pig MBP but not many other tested proteins. Although the biological function of this proteolytic activity is not known, it is clear that MBP-hydrolyzing Abs may play an important role in MS pathogenesis.

CONCLUSIONS

The findings display the generation by the immune systems of individual MS patients of a variety of polyclonal IgGs, IgMs, and IgAs with different proteolytic properties, which hydrolyze MBP, the major protein component of the myelin-proteolipid shell of axons and a well-known MS autoantigen.

[Human milk lactoferrin hydrolyzes nucleoside-5'-triphosphates]

Lactoferrin (LF) is a main iron-transfering glycoprotein of human barrier body fluids, blood and milk. LF, a protein of the acute phase, is responsible for nonspecific cells defense against microbial and viral infection and cancer diseases. LF is an important component of the passive immunity of newborns system. LF, an extremely polyfunctional protein, is the object of intensive investigations. In this work electrophoretically homogeneous LF from human milk was prepared. Affinity chromatography of LF on Blue Sepharose separated the protein into several distinct isoforms with different affinities to this resin. Two of this isoforms possess nucleoside-5'-triphosphate-hydrolyzing activity. Using several methods including in-gel ATPase activity assays, we show that ATP (and others NTP) hydrolysis is an intrinsic property of LF, and that LF is the major ATPase of human milk. It was shown that ATP-hydrolyzing site is located in C-lobe of LF.

Comparison of enzymatic properties of DNA-abzymes and human DNAses

DNA-hydrolyzing antibodies (DNA-abzymes, Abz) were shown to be good biochemical markers of some autoimmune diseases such as systemic lupus erythematosus (SLE) and multiple sclerosis (MS). To better understand mechanisms of abzyme generation, one needs to know optimal conditions for DNA hydrolysis by DNA-abzymes, as well as their enzymatic properties in comparison with those of enzymes possessing the same activity. In contrast to human urine deoxyribonucleases, DNA-hydrolyzing antibodies efficiently digested both single- and double-strand DNA. It was shown that polyclonal antibodies (Abs) in MS may contain up to several types of DNase activities, either activated by metal ions or not.

Characteristics of lipids imbalance in patients with tick-borne encephalitis

Using a novel approach, we have analyzed 30 parameters characterizing detailed spectrum and fractional content of LPs in plasma of patients with tick-borne encephalitis (TBE). The blood plasma of all TBE patients (30 patients), as compared with that of healthy individuals (120 patients), is characterized by decreased concentrations of many LP subfractions and of the total concentration of all plasma LPs (hypolipoproteinemia). The observed difference in some parameters was statistically significant. Using computer-assisted factor analysis, we have shown that according to these 30 parameters TBE patients are similar to patients with multiple sclerosis and systemic lupus erythematosus. The results provide grounds for using data on blood plasma LPs as additional criteria for diagnosis of TBE.

Strong changes in lipoproteins and autoantibodies of blood serum of the Tundra Nency population as a result of environmental radiation on the territory they inhabit

As a result of large-scale nuclear tests on the Novaya Zemlya test site (1955-62) the Tundra Nentsy population of Yamal-Nentsy autonomous region (YNAR) fell under the constant influence of incorporated radioactive isotopes (137Cs and 90Sr). Therefore, it is very important to analyze a possible spectrum of diseases of Tundra Nentsy population.

Casein-hydrolyzing activity of sIgA antibodies from human milk

During pregnancy and immediately after delivery (i.e. at the beginning of lactation), the female organism is frequently characterized by an immune status similar to that of patients with autoimmune diseases. In addition, lactation is associated with an appearance of catalytically active antibodies or abzymes (Abzs) with DNAse, RNase, ATPase, amylolitic, protein kinase and lipid kinase activities in breast milk. However, until now there were no examples of human milk Abzs with a proteolytic activity. We present the first evidence that electrophoretically and immunologically homogeneous human milk sIgAs possess a beta-casein-hydrolyzing activity different from known proteases. Abzs specifically hydrolyze both human and bovine beta-caseins but not many other proteins tested. Using different methods including in situ analysis of proteolytic activity in a gel after SDS-PAGE it was shown that the observed proteolytic activity is an intrinsic property of human milk polyclonal sIgAs. Specific inhibitors of acidic and thiol proteases demonstrated a weak effect on proteolytic activity of Abzs, while a specific inhibitor of serine proteases (AEBSF) significantly inhibited the proteolytic activity of the abzymes. The K(M) value for human casein as a substrate was estimated (7.3 microM). Our findings suggest that the immune system of clinically healthy mothers can generate IgAs with a beta-casein-specific serine protease-like activity.

Lactoferrin Is the Major Deoxyribonuclease of Human Milk

Lactoferrin is the major iron-transferring protein of human barrier fluids such as blood and milk. It is a polyfunctional protein capable of binding DNA exposed on the surface of various cells. Electrophoretically homogenous lactoferrin was prepared by sequential chromatography of human milk proteins on DEAE-cellulose, heparin-Sepharose, and Sepharose containing immobilized anti-lactoferrin antibodies. By subsequent chromatography on Blue Sepharose the resulting lactoferrin was fractionated into several subfractions with different affinity for the sorbent, and this was associated with separation of additional lactoferrin peaks with DNase activity from the main peak. By various techniques, in particular, by in situ testing the DNase activity of lactoferrin in a DNA-containing gel after SDS-electrophoresis, hydrolysis of DNA was for the first time shown to be an intrinsic property of lactoferrin. The substrate specificity of lactoferrin in hydrolysis of DNA was different from specificities of known human DNases. Hydrolysis of DNA was activated by bivalent metal ions and also by ATP and NAD. Unlike the main fraction of lactoferrin with the highest affinity for Blue Sepharose, all protein subfractions with DNase activity were cytotoxic and suppressed growth of human and mouse tumor cell lines.

Catalytic antibodies in healthy humans and patients with autoimmune and viral diseases

Antibodies have been first characterized as proteins produced by the immune system solely for binding other molecules, called antigens, with the goal of eliciting immune response. In this classical conception, antibodies act similarly to enzymes in specific binding to different molecules but cannot catalyze their chemical conversion. However, in 1986 the first monoclonal catalytic antibodies against a chemically stable analog of the transition state of a reaction were obtained and termed abzymes (Abzs). At present, artificial monoclonal Abzs catalyzing more than 100 distinct chemical reactions have been obtained. The discovery of IgG specifically hydrolyzing intestinal vasoactive peptide in the blood serum of asthma patients stimulated studies of natural Abzs. Numerous Abzs discovered afterwards in sera of patients with various autoimmune diseases, viral disorders, or in the milk of healthy mothers, are capable of hydrolyzing proteins, DNA, RNA, polysaccharides, or nucleotides, as well as to phosphorylate proteins and lipids. The phenomenon of catalysis by auto-Abzs is more and more in research focus. In this review we summarize new data on Abzs applications in basic science, medicine and biotechnology.

[Antibodies to DNA in the blood of patients with tick-borne encephalitis]

A comparison of relative levels of autoantibodies (Abs) to both native (n) and denatured (d) DNA in the blood of 55 patients with tick-borne encephalitis (TBE) was carried out. 31% of patients with TBE was shown to have an increased level Abs to nDNA and 40% of patients demonstrate increased level of Abs to dDNA. The percent of TBE patients with increased concentration of anti-nDNA Abs higher then that in patients with multiple sclerosis (18%) and some other autoimmune diseases (6-18%), but comparable with that for patients with systemic lupus erythematosus (38%) and polymyositis (42%). In contrast to patients with systemic lupus erythematosus and multiple sclerosis, the level of Abs to nDNA in patients with TBE is higher than the level of Abs to dDNA. Correlation coefficients of Ab levels to both n- and dDNA were estimated for group of patients in whole and for separate subgroups with different type of disease (temperature reaction, feverishness and meningitis). Analysis of correlation between titres of anti-DNA Abs and three standard biochemical markers of TBE (activity of aspartate- and alanine-aminotransferases, and concentration of whole bilirubin) for 22 patients with TBE was carried out. Statistically significant correlation was revealed only between the level of Abs to nDNA and activities of aspartate- and alanine-aminotransferases, correlation coefficients are equal to +0.44 and +0.48, respectively.

Human Deoxyribonucleases

Although mammalian deoxyribonucleases were discovered more than 60 years ago, interest in these enzymes is not weakening. During the last decade, intensive studies of human DNases culminated in discovery of several novel enzymes exhibiting DNase activity. These include an unusual DNase, lactoferrin. For some enzymes, their three-dimensional structure and molecular mechanisms underlying their functioning have been elucidated. In patients with some autoimmune and viral diseases, catalytic antibodies also contribute to alternative pathways of DNA hydrolysis. Some enzymes exhibiting DNase activity play an important role in pathogenesis of various diseases and also in programmed cell death (apoptosis). This review highlights recent achievement in human deoxyribonuclease research. It also considers mechanisms of DNA hydrolysis. The review also summarizes modern data on the biological role of these enzymes in functioning of the human organism, realization of its protective mechanisms, and possible applications of DNases in medicine.

Catalytic nucleotide-hydrolyzing antibodies in milk and serum of clinically healthy human mothers

BACKGROUND

In humans, pregnancy and lactation are associated with the production of catalytically active antibodies (abzymes) in serum and breast milk. However, the substrate specificities of the abzymes in these biological fluids, particularly breast milk, have not been studied

MATERIAL/METHODS

IgG fractions were isolated from human milk by subsequent steps of chromatographic purification on Protein-A Sepharose, DEAE-cellulose, and anti-IgG Sepharose. The nucleotide-hydrolyzing activity of electrophoretically homogeneous IgG antibodies was measured using 32P-labeled nucleotides and TLC.

RESULTS

We demonstrated by different methods that IgG antibodies from the serum and milk of clinically healthy human mothers are able to hydrolyze ribo- and deoxyribonucleoside-5'-mono, di- and triphosphates; this nucleotide-hydrolyzing activity was also present in Fab fragments of the IgG molecule. Affinity modification of the milk IgG oligomeric form by chemically reactive derivatives of ATP led to preferential modification of the L-chain. However, after separation of the subunits by SDS electrophoresis, an in-gel assay showed ATP-hydrolyzing activity in various oligomeric forms of IgG subunits (H2L2, H2L and HL), while the separated heavy (H) and light (L) chains were not catalytically active. The Km and Vmax values characterizing the interaction of IgG with nucleotides were estimated.

CONCLUSIONS

Our findings speak in favor of the generation of a variety of polyclonal nucleotide-hydrolyzing antibodies by the immune system of clinically healthy mothers.

[Association between DNA antibodies levels in the blood of patients with multiple sclerosis and clinical presentation of the disease]

Multiple sclerosis (MS) as an autoimmune disease is characterized by occurrence of high titres of antibodies (AB) to cell structures and autoantigens. Various AB-mediated effector mechanisms can participate directly in the pathogenesis of demyelinisation damaging myelin, oligodendrocytes and nervous fibres. Antinuclear AB, including anti-DNA AB are an example of activation of humoral immunity in MS. Pathogenetic and clinical value of these AB is investigated insufficiently. The aim of this study was estimation of the AB titers in MS patients from two populations of Russia in relation to clinical features of MS. Results of examination of 83 patients with definite MS from Novosibirsk and Moscow (49 and 34 patients) are analyzed. Groups of comparison consisted of healthy donors and patients with SLE of the same age. Use of identical methods in the analysis of the data received in two various populations made the data objective as much as possible and revealed the strongest clinico-biochemical associations. Levels of AB to both native and denaturated DNA were studied. Comparison of several test-systems showed that the system produced by "Specialized scientific Labs" Company has the best sensitivity. In two populations of MS patients the levels of AB in plasma were similar and associated between each other, higher than in donors, but lower than in SLE patients. In both groups MS patients with secondary progressive MS had higher percent of samples of plasma with average and high levels of AB. In the Novosibirsk group associations of levels of AB with parameters of disease severety (EDSS and a number of FS scales) were seen. In the Moscow group levels of AB to DNA were significantly associated with time from the disease onset to certain level of disability (EDSS 3); both the analysis of average values and the correlation analysis showed a weak association of AB to DNA level and MS duration. The data testify that AB to DNA play a more important role in MS pathogenesis than was considered earlier. Catalytic AB as a part of anti-DNA AB may play a special role.

DNA-hydrolyzing antibodies from sera of autoimmune-prone MRL/MpJ-lpr mice

Catalytically active antibodies (abzymes) hydrolyzing proteins, polysaccharides, ATP, DNA, and RNA have been detected in the sera of patients with various autoimmune and some viral diseases, but abzymes from the sera of animals are practically unstudied. The development of lupus-like autoimmune disease of MRL/MpJ-lpr mice is an experimental model for study of autoimmune pathologies and immunopathogenesis. In this work, homogeneous IgG preparations were isolated from the sera of MRL/MpJ-lpr mice. These antibodies (Abs), their Fab-fragments, and isolated light chains were shown to possess catalytic activity in DNA hydrolysis, whereas Abs from the sera of control healthy mice did not hydrolyze DNA. The data demonstrate that DNA hydrolyzing activity is an intrinsic property of Abs from MRL/MpJ-lpr mice. It was shown that various markers of autoimmune pathologies (level of total protein concentration in urea (proteinuria), Abs titers to native and denatured DNA, and DNA-hydrolyzing activity of IgG) increased in animals with aging, but they noticeably increased (2-22 times) only after appearance of obvious indicators of pathology independently of age. The highest increase in proteinuria (25-fold), anti-DNA Abs titers (12-19-fold), and abzyme activity (120-fold) was found in mice after their immunization with DNA-protein complex.

Dynamics of antibody nuclease activity in blood of women during pregnancy and lactation

In human milk we previously found catalytic antibodies (abzymes) catalyzing hydrolysis of DNA, RNA, NMP, NDP, and NTP and also phosphorylation of proteins and lipids. In the present study we have analyzed nuclease activities of antibodies in blood of women during pregnancy and lactation. Blood of healthy male and female volunteers lacked catalytically active antibodies, whereas antibodies from blood of pregnant women hydrolyzed DNA and RNA and their relative activity varied over a wide range. Relative blood abzyme activities significantly increased after delivery and at the beginning of lactation. The highest abzyme activity was observed in blood of parturient women. Although the dynamics of changes in antibody DNase activity during pregnancy was rather individual for each woman, there was a common trend in the increase in antibody activity in the first and/or third trimester of the pregnancy. The DNase activity of IgG and IgM from blood of healthy pregnant women was 4-5 times less than that from pregnant women with pronounced autoimmune thyroiditis.

Multiple enzymic activities of human milk lactoferrin

Lactoferrin (LF) is a Fe3+-binding glycoprotein, first recognized in milk and then in other human epithelial secretions and barrier fluids. Many different functions have been attributed to LF, including protection from iron-induced lipid peroxidation, immunomodulation and cell growth regulation, DNA binding, and transcriptional activation. Its physiological role is still unclear, but it has been suggested to be responsible for primary defense against microbial and viral infection. We present evidence that different subfractions of purified human milk LF possess five different enzyme activities: DNase, RNase, ATPase, phosphatase, and malto-oligosaccharide hydrolysis. LF is the predominant source of these activities in human milk. Some of its catalytically active subfractions are cytotoxic and induce apoptosis. The discovery that LF possesses these activities may help to elucidate its many physiological functions, including its protective role against microbial and viral infection.

Amylolytic activity of IgM and IgG antibodies from patients with multiple sclerosis

IgG and IgM antibodies from the sera of patients with multiple sclerosis (MS) were found to possess amylolytic activity hydrolyzing alpha-(1-->4)-glucosyl linkages of maltooligosaccharides, glycogen, and several artificial substrates. Individual IgM fractions isolated from 54 analyzed patients with the clinically definite diagnoses of MS had approximately three orders of magnitude higher specific amylolytic activity than that for healthy donors, whereas IgG from only a few patients had high amylolytic activity. Strict criteria were used to prove that the amylolytic activity of IgMs and IgGs is their intrinsic property and is not due to any enzyme contamination. Fab fragments produced from IgM and IgG fractions of the MS patients displayed the same amylolytic activity. IgMs from various patients demonstrated different modes of action in hydrolyzing maltooligosaccharides.

[The mechanism of supercoiled DNA recognition by eukaryotic type I topoisomerases. II. A comparison of the enzyme interaction with specific and nonspecific oligonucleotides]

Data on the interaction of DNA type I topoisomerases from the murine and human placenta cells with specific and nonspecific oligonucleotides of various structures and lengths are summarized. The relative contributions of various contacts between the enzymes and DNA that have previously been detected by X-ray analysis to the total affinity of the topoisomerases for DNA substrates are estimated. Factors that determine the differences in the enzyme interactions with specific and nonspecific single- and double-stranded DNAs are revealed. The results of the X-ray analysis of human DNA topoisomerase I are interpreted taking into account data on the comprehensive thermodynamic and kinetic analysis of the enzyme interaction with the specific and nonspecific DNAs.

[The mechanism of specific cleavage of supercoiled DNA by human DNA topoisomerase I: the effect of ligand structure on the catalytic step of reaction]

Eukaryotic DNA topoisomerase I (Topo) regulates the topological state of cell DNA and plays an important part in replication, transcription, repair, and recombination. Factors affecting the specific recognition of topologically stressed DNA were analyzed on the basis of the thermodynamic and kinetic data on the Topo-DNA interaction and the X-ray data on human Topo. A model was advanced for possible structural changes occurring in the ligand after initial recognition. The effect of conformational changes in specific DNA on the catalytic stage of the reaction was analyzed.

[The mechanism of the supercoiled DNA recognition by eukaryotic type I topoisomerases. I. The enzyme interaction with nonspecific oligonucleotides]

Interaction of the DNA type I topoisomerases from the murine and human placenta cells with nonspecific oligonucleotides was analyzed. The contributions of strong and week nonspecific electrostatic, van der Waals's, and hydrophobic interactions, and hydrogen bonding of the enzymes to the complex formation with the single- and double-stranded DNAs were determined. The factors that determine the top-priority recognition of the topologically stressed DNA were revealed. The results were interpreted in comparison with the X-ray analysis data for human DNA topoisomerase I.

[Assessment of the status of biological health of the population of tundra Nentsy inhabiting northwestern Siberia from data on analysis of autoantibodies and lipoproteins from blood donors]

As a result of large-scale nuclear explosion on Novaya Zemlya test site (1955-62) the Tundra Nentsy population of Yamal-Nentsy autonomous region (YNAR) fell under constant influence of incorporated radioactive isotopes (137Cs and 90Sr). Therefore, it is very important to analyze a possible spectrum of diseases of Tundra Nentsy population. We have developed recently a new method for determination of concentrations of all main fraction and subfraction of lipoproteins (LP, 30 parameters) in human sera using small-angle X-ray scattering, and a general mathematical model to describe LP composition in human blood. The analysis of the 30 parameters characterizing fine spectrum of LPs in 374 YNAR natives showed that only approximately 10% of the donors are normal, while the indices for approximately 90% of the test subjects fall into the range of different pathologies (3-8% incidence in normal population, according to epidemiological studies). Moreover, we found that approximately 41% of European and approximately 56% of Tundra Nentsy have high level of autoantibodies to DNA and cardiolopine like the same for autoimmune diseases patients.

Human catalytic RNA- and DNA-hydrolyzing antibodies

In patients with autoimmune diseases, anti-idiotypic antibodies directed to nucleoprotein complexes, DNA, and enzymes that participate in nucleic acid metabolism may be induced spontaneously by primary antigens and can have characteristics of the primary antigen, including catalytic activity. The first natural catalytic antibody, now termed abzyme, which hydrolyzes intestinal vasoactive peptide, was discovered by Paul et al. [Science 244 (1989) 1158]. Subsequently, other abzymes able to hydrolyze proteins, DNA, RNA, or polysaccharides have been found in the sera of patients with autoimmune and also viral pathologies. Further, we have discovered in the milk of healthy human mothers antibodies that catalyze the hydrolysis of RNA, DNA, nucleotides, and the phosphorylation of lipids and proteins. The phenomenon of catalysis by autoantibodies is extremely interesting and can potentially be applied to many different objectives including new types of efficient catalysts, evaluation of the functional roles of abzymes in innate and adaptive immunity, and understanding of certain aspects of self-tolerance and of the destructive responses in autoimmune diseases. In this review, we collate methods for purifying and characterizing natural abzymes especially those catalyzing DNA and RNA hydrolysis. We also describe new methods that we have developed to provide rigorous criteria that catalytic activity is an intrinsic property of some antibodies. Some major current themes are discussed as well as potential applications of abzymes in scientific, medical, and biotechnological fields.

Hematopoietic progenitor colony formation in the immunopathogenesis of the autoimmune disorder in MRL/MpJ-lpr mice

Lymphocyte proliferation and apoptosis at different stages of the development of the autoimmune disorder in MRL/MpJ-lpr mice was studied. Hematopoietic progenitor colony formation during the course of the disease was characterized. A detectable difference at the level of lymphocyte proliferation, apoptosis, and the relative amount of BFU-E, CFU-GM and CFU-GEMM cell colonies was revealed between healthy young mice and animals spontaneously developing pronounced symptoms of the autoimmune disorder. The quantity of BFU-E and CFU-GEMM colonies was remarkably increases in aged MRL/MpJ-lpr mice even before clinical manifestation of the disease (proteinuria). An elevated number of CFU-GEMM was accompanied by a striking increase in their size. The study of hematopoietic disturbances in autoimmune MRL/MpJ-lpr mice may be very useful for understanding the mechanism of the autoimmune disease development and searching for new strategies of the correction of the autoimmune disorder.

Catalytic diversity of polyclonal RNA-hydrolyzing IgG antibodies from the sera of patients with systemic lupus erythematosus

Various catalytic antibodies or abzymes have been detected in the sera of patients with several autoimmune pathologies, and recently we have shown that RNase activity is associated with IgGs and IgMs from the sera of patients with systemic lupus erythematosus (SLE) but not with those from the sera of normal humans. Here we present for the first time convincing evidence showing that highly purified SLE IgG, its F(ab) fragments and separated L-chains catalyze RNA hydrolysis. These IgGs hydrolyze RNA about one to three orders of magnitude faster than DNA. The enzymatic properties of the RNase activity of these polyclonal IgGs distinguish them from other known human RNases. Their specific activity in hydrolysis of ribooligoadenylates is 2-100-fold higher than that of RNase A and human serum RNases, and they are markedly more thermolabile. In addition, their specific activities with different oligonucleotide substrates, optimal pHs, apparent K(m) values for substrates, and substrate specificities varied very much for different patients. These findings show that a pool of polyclonal RNA-hydrolyzing IgG, which may be relatively small or extremely large, is generated by the immune system of SLE patients.

Amylolytic activity of IgG and sIgA immunoglobulins from human milk

BACKGROUND

New natural amylolytic abzymes (Abs) for catalytically active antibodies from human milk have been identified and investigated.

METHODS

The amylolytic activity of human milk autoantibodies was studied by TLC and HPLC techniques analyzing the hydrolysis of maltooligosaccharides with different degrees of polymerization and of 4-nitrophenyl 4,6-O-ethylidene-alpha-D-maltoheptaoside (EPS). IgG and sIgA fractions were isolated from human milk by affinity chromatography. After SDS-PAGE preparation of native IgG and sIgA and their renaturation, the amylolytic activity was in-gel assayed.

RESULTS

All electrophoretically homogeneous preparations of IgG and its Fab fragments as well as sIgA antibodies possessed alpha-amylolytic activity. The specific activities of these catalytic antibodies varied in the range from 1.83 up to 3.33 kat/kg, which is about one order of magnitude higher than that for IgGs from the sera of cancer patients. IgG and sIgA fractions showed Michaelis constants for hydrolysis of 4-nitrophenyl 4,6-O-ethylidene-alpha-D-maltoheptaoside in the range of 10(-4) M/l. Fractions of autoantibodies from different donors exhibited different modes of action in hydrolysis of maltooligosaccharides, maltose and p-nitrophenyl-alpha-D-glucopyranose.

CONCLUSIONS

IgG antibodies, their Fab fragments, and sIgA fractions isolated from human milk of healthy women possessed amylolytic activity in the hydrolysis of maltooligosaccharides and several artificial substrates.

Inhibition of human DNA topoisomerase I by new DNA minor groove ligands: derivatives of oligo-1,3-thiazolecarboxamides

A series of novel thiazole-containing oligopeptides (oligo-1,3-thiazolecarboxamides) interesting specifically with the minor groove of DNA was shown to inhibit human DNA topoisomerase I (topo I). Inhibitory effects of thiazole-containing oligopeptides (TCO) increase with the number of thiazole units in such compounds. Inhibitory properties of TCO containing 3 or 4 thiazole units were shown to be 3-10 times better than those of the well-known natural antibiotic, distamycin A containing pyrrole rings. The structure of various additional groups attached to the N-terminus and C-terminus of TCO had no significant effect on TCO interaction with the complex of DNA and topo I. TCO were shown to be capable of binding with double-stranded DNA (dsDNA), and the majority of TCO analyzed were more effective in binding with dsDNA than distamycin A. Possible reasons for the different effects of distamycin A and TCO on the reaction of relaxation catalyzed by topo I are discussed.

Catalytic heterogeneity of polyclonal DNA-hydrolyzing antibodies from the sera of patients with multiple sclerosis

Various catalytic antibodies or abzymes have been detected recently in the sera of patients with several autoimmune pathologies, where their presence is most probably associated with autoimmunization. Recently we have shown that DNase activity is associated with IgGs from the sera of patients with multiple sclerosis (MS) but not with those from the sera of normal humans. Here we present evidence showing that MS IgG, its F(ab) fragments, and separated L-chains catalyze DNA hydrolysis. The properties of the DNase activity of these polyclonal IgGs distinguish them from other known human DNases. In addition, their specific activities with different oligonucleotide substrates and the range of optimal pHs, apparent K(M) values and substrate specificities varied widely for different patients. The findings speak in favor of the generation by the immune systems of individual patients of a variety of polyclonal catalytic IgG pools, from relatively small to extremely large ones.

Comparison of the Level of DNA-Hydrolyzing Polyclonal IgG Antibodies in Sera of Patients with Hashimoto's Thyroiditis and Nontoxic Nodal Goiter

Various catalytically active IgG antibodies or abzymes have been recently detected in the sera of patients with several autoimmune pathologies, where their presence is most probably associated with autoimmunization. Here we show for the first time that IgG from peripheral blood of patients with Hashimoto's thyroiditis and nontoxic nodal goiter possesses DNase activity. The properties of the DNase IgGs distinguished them from other known human DNases. The findings give an evidence in favor of the generation of polyclonal catalytic IgG by the immune system of individual patients with impaired function of the thyroid glands. The relative level of specific activity of IgGs in hydrolysis of DNA increases with the elevation of the relative amount of antibodies against thyroglobulin and with the decrease of thyroid hormone concentrations. All patients with hypothyroidism are characterized by a high level of catalytic antibodies, while elevation of functional activity of the thyroid gland and improvement of the clinical state of the patients lead to decrease of the antibody's enzymic activity.

Effect of different drugs on the level of DNA-hydrolyzing polyclonal IgG antibodies in sera of patients with Hashimoto's thyroiditis and nontoxic nodal goiter

BACKGROUND

DNA-hydrolyzing IgG antibodies have been detected recently in the sera of patients with several autoimmune diseases.

MATERIAL AND METHODS

The relative activity of DNA-hydrolyzing IgG from the sera of patients with Hashimoto's thyroiditis and with non-toxic nodal goiter as a function of the patient's condition were measured. The effect of different drugs on the level of DNA-hydrolyzing IgG, functional activity of thyroid gland, and improvement of clinical condition of two groups of patients were analyzed.

RESULTS

We demonstrate here for the first time that IgG from peripheral blood of patients with Hashimoto's thyroiditis (65%) and non-toxic nodal goiter (38%) possesses DNAse activity. The relative level-specific activity of IgGs in hydrolysis of DNA increases with the enhancement of the relative amount of antibodies against thyroglobulin and all patients with hypothyroidism (namely a reduced concentration of thyroxine and triiodothyronine and enhanced level of thyrotropic hormone) are characterized by a high level of catalytic antibodies.

CONCLUSIONS

The very widely used therapy of patients with thyroxine led only to a temporary change of the hormone concentration in the blood but did not affect the level of DNA-hydrolyzing antibodies. However, treatment with an immunosuppressive drug plaquenil (7-chloro-4(beta-diethylamine-alpha-methylbutylamie)quinoline), significantly decreased the DNA-hydrolyzing activity of Abs, which correlated with enhancement of thyroid hormone concentrations, elevation of functional activity of the thyroid gland, and improvement of the clinical state of the patients.

Lactoferrin and its biological functions

Lactoferrin, a component of mammalian milk, is a member of the transferrin family. These glycoproteins transfer Fe(3+) ions. Lactoferrin is a unique polyfunctional protein that influences cell proliferation and differentiation. It can regulate granulopoiesis and DNA synthesis in some cells. Lactoferrin inhibits prostaglandin synthesis in human milk macrophages and activates the nonspecific immune response by stimulating phagocytosis and complement. It can interact with DNA, RNA, proteins, polysaccharides, heparin-like polyanions, etc.; in some of its effects, lactoferrin is found in complexes with ligands. It was recently demonstrated that lactoferrin also possesses ribonuclease activity and is a transcription factor. The list of known biological activities of lactoferrin is constantly increasing. This review analyzes possible mechanisms of its polyfunctionality.

Catalytic antibodies (abzymes) induced by stable transition-state analogs

This review deals with recent advances in the generation of catalytic antibodies by the immunization of animals with stable transition-state analogs. Characteristic features in the functioning of such abzymes are considered in comparison with traditional enzymes.

Natural catalytic antibodies (abzymes) in normalcy and pathology

This review summarizes literature data on natural abzymes. Peculiar features of their functioning and substrate specificity are considered in comparison with traditional enzymes. Working hypotheses on the possible biological roles of natural abzymes in autoimmune processes and diseases accompanied by disorders of immune status are analyzed.

Phosphorylation of Minor Lipids of Human Milk Tightly Bound to Secretory Immunoglobulin A

Catalytic antibodies or abzymes possessing the different catalytic activities were detected in the sera of patients with various autoimmune pathologies, where their presence is most probably associated with autoimmunization. Normal humans are generally considered to have no abzymes, since no obvious immunizing factors are present. The ability of small fraction of sIgA from human milk to phosphorylate selectively casein in the presence of gamma(32)P-ATP was previously shown to be a property of the Abs. Here we revealed for the first time that the same small fraction of sIgA contains Ab subfraction, which is tightly bound to unusual minor lipids of human milk. The lipids may be phosphorylated in the presence of gamma(32)P-ATP and remain partially bound to Abs after purification of polyclonal sIgA by several sequential chromatographies. These lipids may be effectively separated from sIgA only by gel filtration in a buffer containing 5% dioxane or by extraction of the sIgA solutions with chloroform-methanol mixture. It has been shown that two minor milk phospholipids, similarly to the previously described GM1, GM3 and GD3 gangliosides contain residue of sialic acid, but in conrast to the latter lipids, they can not be oxidized with sodium periodate; alkaline methanolysis of them results in formation of 4 and 5 products respectively, while hydrolysis of the gangliosides gives only one or two products. All the data obtained give an evidence in favor of that the minor lipids tightly bound to sIgA may be considered as new lipids of human milk. It was suggested that phosphorylation of the lipids is catalyzed by sIgA antibodies.

Catalytic heterogenity of polyclonal RNA-hydrolyzing IgM from sera of patients with lupus erythematosus

Various catalytically active IgG antibodies or abzymes have been detected recently in the sera of patients with several autoimmune pathologies including systemic lupus erythematosus (SLE), where their presence is most probably associated with autoimmunization. Here we show for the first time that IgM from peripheral blood of patients with SLE possesses both DNase and RNase activities: these activities were also present in Fab fragments of the IgM. Both specific enzymic activities of IgM from sera of any single patient are usually 5-10 times higher than those of IgG antibodies. The same preparations of IgM hydrolyze RNA about two order of magnitude faster than DNA. The properties of the RNases of IgM and IgG distinguished them from other known pancreatic and human sera RNases. In addition, the specific activities of the RNase activity of polyclonal IgM with the polymer substrates [RNA > poly(U) > or = poly(A) >> poly(C)], the observed range of optimal pHs, of apparent Km values for substrates and of substrate specificities varied very much for different patients. The findings speak in favor of the generation of a relatively small or an extremely large pool of polyclonal catalytic IgM by the immune system of individual patients.

Secretory immunoglobulin A from healthy human mothers' milk catalyzes nucleic acid hydrolysis

The human milk secretory immune system is the first line of protection for the newborn infant against various pathogens. Secretory IgA (sIgA), the typical immunoglobulin found in secretions, can fight infections through many mechanisms. Using different methods, we have shown that sIgA from the milk of healthy women possesses DNAse and RNAse activities. The catalytic center is localized in the light chain of catalytic sIgA, while the DNA-binding center is predominantly formed by its heavy chain. The enzymic properties and substrate specificity of catalytic sIgA distinguish it from other known DNases and RNases. It is reasonable to assume that the milk DNA- and RNA-hydrolyzing antibodies are capable not only of neutralizing viral and bacterial nucleic acids by binding these antigens as well as by hydrolyzing them. The DNA-hydrolyzing activity of Abs raises the possibility that these catalytic Abs may provide protective functions for the newborn through the hydrolysis of viral and bacterial nucleic acids.

Human milk lactoferrin binds two DNA molecules with different affinities

Evidence is presented that lactoferrin (LF), an Fe3+-binding glycoprotein, possesses two DNA-binding sites with different affinities for specific oligonucleotides (ODNs) (Kdl = 8 nM; Kd2 approximately 0.1 mM). The high affinity site became labeled after incubation with affinity probes for DNA-binding sites; like the antibacterial and polyanion-binding sites, this site was shown to be located in the N-terminal domain of LF. Interaction of heparin with the polyanion-binding site inhibits the binding of ODNs to both sites. These data suggest that the DNA-binding sites of LF coincide or overlap with the known polyanion and antimicrobial domains of the protein.

Variability of Substrate Specificity of Serum Antibodies Obtained from Patients with Different Autoimmune and Viral Diseases in Reaction of tRNA Hydrolysis

Recently we have shown that the substrate specificity of catalytic IgG isolated from sera of patients with Hashimoto's thyroiditis, systemic lupus erythematosus (SLE), polyarthritis and hepatitis B for classic poly(N) homopolynucleotide substrates and for specific tRNA(Phe) with compact and stable structure was correlated with the type of disease. At the same time the cleavage specificity was different in comparison with that of all known human RNases. Here we investigated for the first time the hydrolysis by the IgGs isolated from sera of 31 patients with different diseases of the in vitro transcript of human mitochondrial tRNA(Lys) which has less stable structure as compared to tRNA(Phe). The level of activity was strongly dependent on the patient, but in general increased in the order: hepatitis B </= Hashimoto's thyroiditis < SLE. The pH dependencies and various salts effects also varied for Abs from the sera of different patients. Nevertheless, the RNase activity of all IgGs was specifically stimulated by Mg(2+) ions, that essentially completely suppress the activity of all known human RNases. In contrast to the classical substrates, no correlation between patient's IgG cleavage specificity and a specific disease was revealed; each patient demonstrated an individual repertoire of polyclonal RNA-hydrolyzing IgGs independently of the disease.

Human milk lactoferrin binds ATP and dissociates into monomers

The physiological role of lactoferrin (LF) is still unclear, but it has been suggested to be responsible for primary defence against microbial infections. Many different unique functions have been attributed to LF, including DNA and RNA binding, and transport into the nucleus, where LF binds to specific DNA sequences and activates transcription. Here we present evidence that in addition to the above (and below) mentioned functions LF binds ATP with a stoichiometry of 1 mole of nucleotide per mole of the protein and a Kd = 0.3 mM. The ATP-binding site is localized in the C-terminal domain of LF, in contrast to the antibacterial and polyanion-binding sites, which are located in the N-terminal domain. Binding of ATP by LF leads to dissociation of its oligomeric forms and to a change of the protein's interaction with polysaccharides, DNA and proteins.

Polyclonal antibodies from blood and cerebrospinal fluid of patients with multiple sclerosis effectively hydrolyze DNA and RNA

It is known that in the blood of patients with some autoimmune diseases catalytically active antibodies hydrolyzing proteins, DNA, and RNA may be detected. In the present work homogeneous preparations of IgG antibodies (Ab) possessing high affinity for nucleic acids (NA) were obtained for the first time from blood and cerebrospinal fluid of patients with multiple sclerosis (MS). The fraction of IgG Ab as well as its Fab fragments and isolated light chains of both kappa- and lambda-types were shown to catalyze effectively the hydrolysis of DNA and RNA. It is shown by different methods that the capability for nucleic acid hydrolysis is an intrinsic property of the polyclonal Ab. NA-hydrolyzing Ab were detected in the blood of 69 of 72 and in the cerebrospinal fluid of 5 of 5 examined MS patients, while they were not detected in the blood of any of 50 healthy donors examined. Comparison of relative rates of RNA hydrolysis and of the substrate specificity in hydrolysis of various model RNAs--cCMP, poly(U), poly(A), and poly(C)--revealed pronounced differences of MS antibodies from ribonucleases of human blood, ribonuclease A, and all earlier described abzymes. The abzymes are usually characterized by relatively low specific activities in comparison with that of normal enzymes catalyzing analogous reactions. Ab from the blood of MS patients are the first example of autoabzymes whose specific activity in RNA hydrolysis is comparable or even higher than that of pancreatic ribonuclease A--one of the most active RNA-hydrolyzing enzymes.

Catalytic DNA- and RNA-hydrolyzing antibodies from milk of healthy human mothers

Various catalytically active antibodies (Abs), or abzymes, have been detected recently in the sera of patients with autoimmune pathologies, in whom their presence is probably associated with autoimmunization. Normal humans are generally not considered to have abzymes, since no obvious immunizing factors are present. Here is shown by different methods that IgG from the milk of normal females possesses both DNase and RNase activities. The activities were also present in the IgG F(ab')2 and Fab fragments. Affinity modification of IgG by the chemically reactive derivative of an oligonucleotide led to preferential modification of the L chain of IgG. After separation of the subunits by sodium dodecyl sulfate electrophoresis in a gel containing DNA, an in-gel assay showed DNase activity in the L chain. The L chain separated by affinity chromatography on DNA-cellulose was catalytically active. These findings speak in favor of the generation of catalytic Abs by the immune system of healthy mothers. It is known that the treatment of adults with DNases and RNases offers protection from viral and bacterial diseases. Since breast milk protects the infants from infections until the immune system is developed, this raises the possibility that catalytic Abs like nucleases, may possess a protective role.

Secretory immunoglobulin A from human milk catalyzes milk protein phosphorylation

This article presents evidence that protein kinase activity is an intrinsic property of secretory immunoglobulin A (sIgA) from milk of healthy human mothers. Polyclonal sIgA was purified by sequential chromatography on protein A-Sepharose, DEAE-cellulose, and gel filtration on Toyopearl HW-55 and Sepharose 4B columns. Its purity was established by one- and two-dimensional SDS-PAGE. The protein kinase activity was inhibited by specific antibodies (Abs) against sIgA, and was stable to acidic and alkaline conditions. Catalytic sIgA showed optimal reaction conditions (pH and MgCl2 concentration) and substrate specificity different from those of known protein kinases; i.e., sIgA phosphorylated the serine residues of various milk proteins in the presence of different gamma-[32P]nucleoside- and deoxynucleoside-5'-triphosphates. The homogeneous Fab fragment of sIgA also showed kinase activity. An ATP-binding activity of fractions of sIgA was demonstrated by affinity chromatography on ATP-Sepharose and by covalent binding of an affinity analog of ATP; this activity was mediated by the L chain of sIgA. The authors believe these observations are the first example of the catalytic activity of IgA Abs and of natural catalytic Abs with synthetic activity. In addition, the findings suggest the likelihood that catalytic Abs are generated by the immune system of healthy mothers.

Human breast milk immunoglobulins G hydrolyze nucleotides

Catalytically active antibodies, abzymes, appear in the blood of mammals immunized with the analogs of transition state or in the case of autoimmune diseases. Until recently, it was not shown whether abzymes exist in the blood of apparently healthy subjects. We have discovered that secretory IgA (sIgA) from the milk of healthy mothers catalyze phosphorylation of a variety of proteins and that IgG can hydrolyze DNA and RNA. In this study for the first time it is shown that IgG from human milk (and their Fab-fragments) also catalyze hydrolysis of nucleoside mono-, di-, and triphosphates. The data meet certain stringent criteria, unambiguously indicating that the observed catalytic activity is associated with IgG rather than contaminating enzymes. Although the nucleotide-binding site of IgG is located in the light antibody chain, L-chains per se cannot hydrolyze NTP unlike the DNA-hydrolyzing abzymes. Kinetic and thermodynamic parameters that characterize the interaction of NTP and dNTP with IgG-abzymes were analyzed. Possible reasons for appearance of polyclonal abzymes with different catalytic activities in the milk of healthy mothers are considered.

Interaction of human milk lactoferrin with ATP

Human lactoferrin exhibits many unique properties. It is known as one of the most important factors that provide nonspecific defense of cells against bacteria, viruses, and carcinogenesis, as well as an important component of a specific system responsible for the passive immunity of newborns. As a compound with extremely broad spectrum of functions many of which were not elucidated so far, lactoferrin is intensely studied. In this study we obtained electrophoretically and immunologically homogenous preparations of lactoferrin from human milk. Using various methods, we were the first to show that the fraction of lactoferrin, which displays an increased affinity for Sepharose Blue, forms complexes with ATP with a stoichiometry of 1 mole ATP per mole protein. It is shown that the ATP-binding site is located in the C-terminal domain of the lactoferrin molecule. The binding of ATP results in the dissociation of tetrameric forms of the protein and a change in the mode of interaction of lactoferrin with polysaccharides and other proteins. The data may be used in analysis of the possible reasons for multifunctional properties of lactoferrin and possible ways of regulation of its functions.