A serine protease secreted from Bacillus subtilis cleaves human plasma transthyretin to generate an amyloidogenic fragment

Aggregation of human wild-type transthyretin (hTTR), a homo-tetrameric plasma protein, leads to acquired senile systemic amyloidosis (SSA), recently recognised as a major cause of cardiomyopathies in 1-3% older adults. Fragmented hTTR is the standard composition of amyloid deposits in SSA, but the protease(s) responsible for amyloidogenic fragments generation in vivo is(are) still elusive. Here, we show that subtilisin secreted from Bacillus subtilis, a gut microbiota commensal bacterium, translocates across a simulated intestinal epithelium and cleaves hTTR both in solution and human plasma, generating the amyloidogenic fragment hTTR(59-127), which is also found in SSA amyloids in vivo. To the best of our knowledge, these findings highlight a novel pathogenic mechanism for SSA whereby increased permeability of the gut mucosa, as often occurs in elderly people, allows subtilisin (and perhaps other yet unidentified bacterial proteases) to reach the bloodstream and trigger generation of hTTR fragments, acting as seeding nuclei for preferential amyloid fibrils deposition in the heart. Peterle et al. show that a subtilisin like serine protease secreted from gut microbiota Bacillus subtilis cleaves the wild-type human transthyretin (hTTR) to generate an amyloidogenic peptide. High propensity of the hTTR fragment to form pathogenic protein aggregates implicates the serine protease in the pathogenesis of acquired senile systemic amyloidosis

Ceruloplasmin Reduces the Lactoferrin/Oleic Acid Antitumor Complex-Mediated Release of Heme-Containing Proteins from Blood Cells

Our previous study showed that not only bovine lactoferrin (LF), the protein of milk and neutrophils, but also the human species forms complexes with oleic acid (OA) that inhibit tumor growth. Repeated injections of human LF in complex with OA (LF/8OA) to hepatoma-carrying mice decelerated tumor growth and increased animals’ longevity. However, whether the effect of the LF/8OA complex is directed exclusively against malignant cells was not studied. Hence, its effect on normal blood cells was assayed, along with its possible modulation of ceruloplasmin (CP), the preferred partner of LF among plasma proteins. The complex LF/8OA (6 μM) caused hemolysis, unlike LF alone or BSA/8OA (250 μM). The activation of neutrophils with exocytosis of myeloperoxidase (MPO), a potent oxidant, was induced by 1 μM LF/8OA, whereas BSA/8OA had a similar effect at a concentration increased by an order. The egress of heme-containing proteins, i.e., MPO and hemoglobin, from blood cells affected by LF/8OA was followed by a pronounced oxidative/halogenating stress. CP, which is the natural inhibitor of MPO, added at a concentration of 2 mol per 1 mol of LF/8OA abrogated its cytotoxic effect. It seems likely that CP can be used effectively in regulating the LF/8OA complex’s antitumor activity

Potential role of lactoferrin in early diagnostics and treatment of Parkinson disease

Incidence of Parkinson disease progressively grows with increasing age and percentage of elderly people in the global population. Clear understanding of the causes of dopaminergic neurons death in Substantia nigra and Parkinson disease pathogenesis are currently absent, not speaking of an efficient therapy. However, an early diagnosis of dopaminergic neurons degeneration and prescription of dopamine replacement therapy significantly slow down the rate of symptoms progression. An increased concentration of iron in Substantia nigra of Parkinson disease patients has been shown in several studies. In this review we summarized the data concerning a potential significance of lactoferrin, the iron-binding protein of exocrine secretions and neutrophils, for early diagnosis and treatment of Parkinson disease. Salivary and lacrimal lactoferrin levels in Parkinson disease patients were higher than those observed in the control group. Plasma levels of lactoferrin inversely correlated with Parkinson disease severity even after treatment with Levodopa, a dopamine agonist, and with monoaminooxidase inhibitors. Lactoferrin levels in cerebrospinal fluid of Parkinson disease patients negatively correlated with the tumor necrosis factor-alpha concentration. Lactoferrin treatment of rodents with several experimental models of Parkinson disease (induced by rotenone, MPTP) protected neurons and mitigated the symptoms of neurodegeneration. Some contradictions about the positive effects of lactoferrin as a remedy in Parkinson disease animal models and possible participation of lactoferrin in accumulation of iron in neurons are discussed.</jats:p

Biochemical and biological activity of arginine deiminase from Streptococcus pyogenes M22.

Streptococcus pyogenes (group A Streptococcus - GAS) is an important gram-positive extracellular bacterial pathogen responsible for a number of suppurative infections. This microorganism developed complex virulence mechanisms to avoid host defense. We have previously revealed that Supernatant of Destroyed Streptococcal Cells (SDSC) from GAS type M22 causes endothelial cells’ dysfunction, inhibits cellular adhesion, migration, metabolism and proliferation in a dose-dependent manner without affecting cells’ viability. The present work is aimed at isolation and characterization of a component from GAS type M22 supernatant that suppresses proliferation of endothelial cells EA.hy926. Isolating a protein possessing antiproliferative activity allowed identifying arginine deiminase (AD). Further study showed that the enzyme is most active at pH 6.8. Calculating Km and Vmax gave the values of 0.67 mM and 42 s-1, respectively. Distinctive feature of AD purified from GAS type M22 is the closest to neutral pH optimum of activity and the maximal rate of the catalytic process compared with such of the enzyme from other microorganisms. AD from GAS type M22 suppressed the proliferative activity of endothelial cells in a dose-dependent mode. At the same time in the presence of AD the share of cells in G0/G1 phase increased. When L-Arg was added at increasing concentrations to the culture medium containing 3 µg/ml AD, the enzyme’s capacity to inhibit cell proliferation became partly depressed. The proportion of cells in phases S/G2 increased concomitantly, though the cells did not fully recover their proliferation activity. All this allows regarding AD from GAS type M22 as a prospective pharmacy for suppression of excessive cell proliferation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Binding of lactoferrin to the surface of low-density lipoproteins modified by myeloperoxidase prevents intracellular cholesterol accumulation by human blood monocytes

Myeloperoxidase (MPO) is a unique heme-containing peroxidase that can catalyze the formation of hypochlorous acid (HOCl). The strong interaction of MPO with low-density lipoproteins (LDL) promotes proatherogenic modification of LDL by HOCl. The MPO-modified LDL (Mox-LDL) accumulate in macrophages, resulting in the formation of foam cells, which is the pathognomonic symptom of atherosclerosis. A promising approach to prophylaxis and atherosclerosis therapy is searching for remedies that prevent the modification or accumulation of LDL in macrophages. Lactoferrin (LF) has several application points in obesity pathogenesis. We aimed to study LF binding to Mox-LDL and their accumulation in monocytes transformed into macrophages. Using surface plasmon resonance and ELISA techniques, we observed no LF interaction with intact LDL, whereas Mox-LDL strongly interacted with LF. The affinity of Mox-LDL to LF increased with the degree of oxidative modification of LDL. Moreover, an excess of MPO did not prevent interaction of Mox-LDL with LF. LF inhibits accumulation of cholesterol in macrophages exposed to Mox-LDL. The results obtained reinforce the notion of LF potency as a remedy against atherosclerosis.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author