How human IgGs against myelin basic protein (MBP) recognize oligopeptides and MBP

Maximally Expressed miRNAs of Milk in Cells, Plasma and Lipid Fraction of Human Milk and Antibodies-Abzymes Catalyzing Their Hydrolysis

As shown in many studies, one of the earliest statistically significant indicators of the development of many autoimmune diseases (ADs) is the appearance in the blood of antibodies with catalytic activities (abzymes) hydrolyzing different autoantigens. Antibodies-abzymes having different enzymatic activities are a specific and essential feature of some ADs. Most abzymes are harmful to humans. Free histones in the blood are damage-associated proteins, and their administration to animals drives systemic inflammatory and toxic effects. Myelin basic protein (MBP) is the most critical component of the axon myelin-proteolipid sheath. Hydrolysis of MBP by abzymes leads to the disruption of nerve impulses. Here, we analyzed the possible pathways for the formation of unusual antibodies and abzymes that exhibit polyspecificity in recognition during complex formation with partially related antigens and possess the ability to catalyze several different reactions for the first time. Using IgGs of HIV-infected and multiple sclerosis patients against five individual histones (H1–H4), MBP, and DNA, it was first shown that abzymes against each of these antigens effectively recognize and hydrolyze all three antigens: histones, MBP, and DNA. The data obtained indicate that the formation of such polyspecific abzymes, whose single active center can recognize different substrates and catalyze several reactions, can occur in two main ways. They can be antibodies against DNA–protein complex hybrid antigenic determinants containing proteins and nucleic sequences. Their formation may also be associated with the previously described phenomenon of IgG extensive LH half-molecule (containing one L-light and one H-heavy chains) exchange leading to H₂L₂ molecules containing HL halves with variable fragments recognizing different antigens.

Catalytic Antibodies in Bipolar Disorder: Serum IgGs Hydrolyze Myelin Basic Protein

The pathogenesis of bipolar affective disorder is associated with immunological imbalances, a general pro-inflammatory status, neuroinflammation, and impaired white matter integrity. Myelin basic protein (MBP) is one of the major proteins in the myelin sheath of brain oligodendrocytes. For the first time, we have shown that IgGs isolated from sera of bipolar patients can effectively hydrolyze human myelin basic protein (MBP), unlike other test proteins. Several stringent criteria were applied to assign the studied activity to serum IgG. The level of MBP-hydrolyzing activity of IgG from patients with bipolar disorder was statistically significantly 1.6-folds higher than that of healthy individuals. This article presents a detailed characterization of the catalytic properties of MBP-hydrolyzing antibodies in bipolar disorder, including the substrate specificity, inhibitory analysis, pH dependence of hydrolysis, and kinetic parameters of IgG-dependent MBP hydrolysis, providing the heterogeneity of polyclonal MBP-hydrolyzing IgGs and their difference from canonical proteases. The ability of serum IgG to hydrolyze MBP in bipolar disorder may become an additional link between the processes of myelin damage and inflammation.

Secretory immunoglobulin A from human milk hydrolyzes 5 histones and myelin basic protein

Mother's milk provides newborns with various nutrients (e.g., enzymes, proteins, peptides, hormones, antibodies) that help babies grow and protect them from bacterial and viral infections. The functions of many components of breast milk can be very different from their corresponding functions in body fluids of healthy adults. Catalytic antibodies (abzymes) that hydrolyze peptides, proteins, DNA, RNA, and oligosaccharides were detected not only in human milk, but also in the blood sera of autoimmune patients. However, abzymes with unexpected synthetic activities (lipids, oligosaccharides, and protein kinase activities) were revealed in milk that were not found in the blood of autoimmune patients. The nutrition of infants with fresh milk has a very specific role; newborns are well protected by antibodies of mother's milk (passive immunity). Protease abzymes were found in the blood sera of autoimmune patients, whereas healthy humans usually do not contain such autoantibodies. Here, we present the first evidence that the milk of healthy mothers contains secretory (s)IgA that effectively hydrolyze 5 histones (e.g., H1, H2A, H2B, H3, and H4) and myelin basic protein (MBP). Several rigid criteria were applied to show that protease activity is an intrinsic property of sIgA. Milk abzymes against 5 histones cannot hydrolyze different control proteins except histones and MBP, whereas autoantibodies against MBP split this protein and 5 histones. Antibodies against histones and MBP exhibit complexation polyreactivity as well as specific and unusual catalytic cross-reactivity. With some exceptions, the specific sites of hydrolysis of H1, H2A, and H2B by sIgA against histones do not coincide with the sites of hydrolysis by abzymes against MBP. On the whole, fresh human milk is a very specific source of many of the most unusual antibodies and abzymes.

HIV-Infected Patients: Cross Site-Specific Hydrolysis of H3 and H4 Histones and Myelin Basic Protein with Antibodies against These Three Proteins

Histones play important roles in chromatin functioning and gene transcription, but in the intercellular space, they are harmful since they stimulate systemic inflammatory and toxic responses. Electrophoretically homogeneous IgGs against myelin basic protein (MBP), as well as H3 and H4 histones, were isolated from sera of HIV-infected patients. In contrast to known classical proteases, these IgGs split exclusively only histones and MBP but no other control proteins. Among 13 sites of hydrolysis of H3 by IgGs against H3 and 14 sites for anti-MBP IgGs, only two sites of the hydrolysis were the same. Between seven cleavage sites of H4 with IgGs against H4 and 9 sites of this histone hydrolysis by antibodies against MBP, only three sites were the same. The sites of hydrolysis of H3 (and H4) with abzymes against these histones and against MBP were different, but several expended protein clusters containing hydrolysis sites are partially overlapped. The existence of enzymatic cross-reactivity of abzymes against H3 and H4 and MBP represents a great menace to humans since due to cell apoptosis, histones constantly occur in human blood. They can hydrolyze MBP of the myelin sheath of axons and play a negative role in the pathogenesis of HIV-infected patients.

HIV-Infected Patients: Cross Site-Specific Hydrolysis of H2a and H2b Histones and Myelin Basic Protein with Antibodies against These Three Proteins

Anti-DNA antibodies are usually produced against histone-DNA complexes appearing during cell apoptosis, while histones are known as damage-associated molecules. A myelin sheath of axons contains myelin basic protein (MBP) playing an important role in the pathogenesis of autoimmune diseases. Antibodies with enzymatic activities (abzymes) are distinctive features of some autoimmune and viral diseases. Abzymes against different proteins can usually only hydrolyze these specific proteins. Using sequential chromatographies of homogeneous IgG preparations from sera of HIV-infected patients on columns with immobilized MBP, H2a, and H2b histones, the anti-MBP, anti-H2a, and anti-H2b antibodies were obtained. It was first shown that IgGs against H2a and H2b effectively hydrolyze these histones and MBP, while anti-MBP split MBP, H2a, and H2b, but no other control proteins. Using the MALDI mass spectrometry, the cleavage sites of H2a, H2b, and MBP by abzymes against these three proteins were found. Among 14 sites of hydrolysis of H2a by IgGs against H2a and 10 sites by anti-MBP IgGs, only one site of hydrolysis was the same for these abzymes. Eleven cleavage sites of H2b with IgGs against H2b and 10 sites of its hydrolysis with antibodies against MBP were different. Anti-H2a, anti-H2b, and anti-MBP abzymes are unpredictable examples of IgGs possessing not only cross-complexation but also catalytic cross-reactivity, which may be a common phenomenon for such abzymes in patients with different autoimmune diseases. The existence of cross-reactivity of abzymes against H2a and H2b histones and MBP represent a great danger to humans since, in contrast with MBP, histones due to cell apoptosis constantly occur in human blood. Anti-H2a, anti-H2b, and anti-MBP can attack and hydrolyze myelin basic protein of the myelin sheath of axons and plays a negative role in the pathogenesis of several pathologies.

Autoantibodies in HIV-infected patients: Cross site-specific hydrolysis of H1 histone and myelin basic protein

Histones act as damage-associated molecules, while anti-DNA antibodies are directed against histone-DNA nucleosomal complexes. Myelin basic protein (MBP) plays an important role in the pathogenesis of multiple sclerosis. Autoantibodies (Abs) with enzymatic activities are the distinctive feature of some autoimmune and viral diseases. Abzymes with proteolytic activity against different proteins specifically hydrolyze only these specific proteins. Using chromatography of IgGs on columns with immobilized H1 histone and then by chromatography of the fraction having an affinity for the histone (eluted upon loading) on MBP Sepharose, the anti-MBP antibodies were obtained. Anti-H1 antibodies were obtained using these columns in reverse order. IgGs against H1 and MBP effectively hydrolyze both H1 histone and MBP but no other control proteins. Using the MALDI mass spectrometry, the cleavage sites of H1 histone and MBP by abzymes against these proteins are found. The hydrolysis of MBP by anti-MBP IgGs occurs at four clusters (22 sites of the hydrolysis) locating at four known antigenic determinants of MBP. Anti-H1 Abs hydrolyze MBP only at one cluster (11 sites of the hydrolysis); this cluster is only partially overlapped with one of the four MBP clusters. Anti-H1 antibodies hydrolyze H1 at five sites of one cluster of the protein when anti-MBP IgGs cleavage this histone at two clusters containing 17 sites of the cleavage. Anti-H1 and anti-MBP abzymes are the first examples of Abs possessing not only with cross-complexing but also with catalytic cross-reactivity. The existence of cross-reactivity of abzymes against histones and MBP represent great danger to humans. © 2018 BioFactors, 45(2):211-222, 2019.