Lysozyme Concentration in Tears‐assessment of Reference Values in Normal Subjects

Aine, Esko; Mörsky, Pertti

doi:10.1111/j.1755-3768.1984.tb08445.x

Cited by 32 publications

(19 citation statements)

References 14 publications

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“…The negative correlation between lysozyme resistance and virulence is in agreement with the observed MIC values of wild type S. suis strains. Most lysozyme sensitive isolates belong to the generally highly invasive serotypes 1 and 2 [6], while most of the lysozyme resistant isolates belong to serotype 9, which are in general effective colonizers of the upper respiratory tract [5], [6], [7]. A similar negative correlation between lysozyme resistance and virulence has been suggested for S. pneumoniae .…”

Section: Discussionsupporting

confidence: 60%

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Lysozyme Resistance in Streptococcus suis Is Highly Variable and Multifactorial

et al. 2012

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Background Streptococcus suis is an important infectious agent for pigs and occasionally for humans. The host innate immune system plays a key role in preventing and eliminating S. suis infections. One important constituent of the innate immune system is the protein lysozyme, which is present in a variety of body fluids and immune cells. Lysozyme acts as a peptidoglycan degrading enzyme causing bacterial lysis. Several pathogens have developed mechanisms to evade lysozyme-mediated killing. In the present study we compared the lysozyme sensitivity of various S. suis isolates and investigated the molecular basis of lysozyme resistance for this pathogen.ResultsThe lysozyme minimal inhibitory concentrations of a wide panel of S. suis isolates varied between 0.3 to 10 mg/ml. By inactivating the oatA gene in a serotype 2 and a serotype 9 strain, we showed that OatA-mediated peptidoglycan modification partly contributes to lysozyme resistance. Furthermore, inactivation of the murMN operon provided evidence that additional peptidoglycan crosslinking is not involved in lysozyme resistance in S. suis. Besides a targeted approach, we also used an unbiased approach for identifying factors involved in lysozyme resistance. Based on whole genome comparisons of a lysozyme sensitive strain and selected lysozyme resistant derivatives, we detected several single nucleotide polymorphisms (SNPs) that were correlated with the lysozyme resistance trait. Two SNPs caused defects in protein expression of an autolysin and a capsule sugar transferase. Analysis of specific isogenic mutants, confirmed the involvement of autolysin activity and capsule structures in lysozyme resistance of S. suis.ConclusionsThis study shows that lysozyme resistance levels are highly variable among S. suis isolates and serotypes. Furthermore, the results show that lysozyme resistance in S. suis can involve different mechanisms including OatA-mediated peptidolycan modification, autolysin activity and capsule production.

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Section: Discussionsupporting

confidence: 60%

“…Lysozyme is found in high concentrations (>500 µg/ml) in several bodily secretions including tears, mucus, milk and saliva [6], [7]. In addition neutrophil granules contain significant amounts of the protein [8], [9], [10].…”

Section: Introductionmentioning

confidence: 99%

Lysozyme Resistance in Streptococcus suis Is Highly Variable and Multifactorial

et al. 2012

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“…Bacteria were plated on BHI agar at a concentration of approximately 200 CFU/plate and replica plated onto BHI agar plates containing 1 mg/ml lysozyme. This concentration of lysozyme was chosen because it was sufficient to completely restrict the growth of the ⌬pgdA mutant, had no effect on WT bacteria, and was relevant during infection (3,24). BHI plates were visually compared to BHI-lysozyme plates for the loss of individual colonies (Fig.…”

Section: Resultsmentioning

confidence: 99%

Listeria monocytogenes Is Resistant to Lysozyme through the Regulation, Not the Acquisition, of Cell Wall-Modifying Enzymes

et al. 2014

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Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is highly resistant to lysozyme, a ubiquitous enzyme of the innate immune system that degrades cell wall peptidoglycan. Two peptidoglycan-modifying enzymes, PgdA and OatA, confer lysozyme resistance on L. monocytogenes; however, these enzymes are also conserved among lysozyme-sensitive nonpathogens. We sought to identify additional factors responsible for lysozyme resistance in L. monocytogenes. A forward genetic screen for lysozyme-sensitive mutants led to the identification of 174 transposon insertion mutations that mapped to 13 individual genes. Four mutants were killed exclusively by lysozyme and not other cell wall-targeting molecules, including the peptidoglycan deacetylase encoded by pgdA, the putative carboxypeptidase encoded by pbpX, the orphan response regulator encoded by degU, and the highly abundant noncoding RNA encoded by rli31. Both degU and rli31 mutants had reduced expression of pbpX and pgdA, yet DegU and Rli31 did not regulate each other. Since pbpX and pgdA are also present in lysozyme-sensitive bacteria, this suggested that the acquisition of novel enzymes was not responsible for lysozyme resistance, but rather, the regulation of conserved enzymes by DegU and Rli31 conferred high lysozyme resistance. Each lysozyme-sensitive mutant exhibited attenuated virulence in mice, and a time course of infection revealed that the most lysozyme-sensitive strain was killed within 30 min of intravenous infection, a phenotype that was recapitulated in purified blood. Collectively, these data indicate that the genes required for lysozyme resistance are highly upregulated determinants of L. monocytogenes pathogenesis that are required for avoiding the enzymatic activity of lysozyme in the blood. Lysozyme is a ubiquitous bactericidal enzyme found in the blood, bodily secretions, and phagocytic cells of all animals (1-3). Lysozyme degrades the bacterial cell wall by hydrolyzing the ␤1-4 linkage between the N-acetylglucosamine (NAG) and Nacetylmuramic acid (NAM) residues that comprise the peptidoglycan backbone, often resulting in bacteriolysis (4). Not surprisingly, many pathogens have evolved mechanisms of lysozyme resistance (5, 6). The best-characterized mechanisms of lysozyme resistance involve the acetylation state of the peptidoglycan, catalyzed by the deacetylase PgdA and/or the acetyltransferase OatA. PgdA deacetylates the amino group of NAG, while OatA O-acetylates NAM, converting the sugar backbone into a poor lysozyme substrate (7,8). pgdA mutants of Streptococcus pneumoniae and oatA mutants of Staphylococcus aureus are lysozyme sensitive, and in each case, lysozyme-sensitive mutants are attenuated in animal models of infection (7-10).Listeria monocytogenes is a facultative intracellular pathogen of animals and humans that causes severe disease in pregnant women and immunocompromised individuals (11). Both PgdA and OatA contribute to lysozyme resistance in L. monocytogenes, and pgdA mutants are attenuated during oral a...

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“…It is extremely abundant in human tears, with an average level of 1568 μg/mL (numbers may vary depending on different samples and methods). 21 Milk and saliva also contain high levels of lysozyme (around 21.4 and 7 μg/mL, respectively). 22,23 The concentrations of lysozyme are lower in serum and urine samples (about 1.7 and 0.18 μg/mL, respectively) from normal human adults.…”

Section: Introductionmentioning

confidence: 99%

Strong and Selective Adsorption of Lysozyme on Graphene Oxide

Li¹,

Mulloor²,

Wang³

et al. 2014

ACS Appl. Mater. Interfaces

112

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Biosensing methods and devices using graphene oxide (GO) have recently been explored for detection and quantification of specific biomolecules from body fluid samples, such as saliva, milk, urine, and serum. For a practical diagnostics application, any sensing system must show an absence of nonselective detection of abundant proteins in the fluid matrix. Because lysozyme is an abundant protein in these body fluids (e.g., around 21.4 and 7 μg/mL of lysozyme is found in human milk and saliva from healthy individuals, and more than 15 or even 100 μg/mL in patients suffering from leukemia, renal disease, and sarcoidosis), it may interfere with detections and quantification if it has strong interaction with GO. Therefore, one fundamental question that needs to be addressed before any development of GO based diagnostics method is how GO interacts with lysozyme. In this study, GO has demonstrated a strong interaction with lysozyme. This interaction is so strong that we are able to subsequently eliminate and separate lysozyme from aqueous solution onto the surface of GO. Furthermore, the strong electrostatic interaction also renders the selective adsorption of lysozyme on GO from a mixture of binary and ternary proteins. This selectivity is confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), fluorescence spectroscopy, and UV–vis absorption spectroscopy.

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Lysozyme Concentration in Tears‐assessment of Reference Values in Normal Subjects

Cited by 32 publications

References 14 publications

Lysozyme Resistance in Streptococcus suis Is Highly Variable and Multifactorial

Lysozyme Resistance in Streptococcus suis Is Highly Variable and Multifactorial

Listeria monocytogenes Is Resistant to Lysozyme through the Regulation, Not the Acquisition, of Cell Wall-Modifying Enzymes

Strong and Selective Adsorption of Lysozyme on Graphene Oxide

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