Effect of Contact Lens Solutions in Stabilizing the Activity of Tear Lysozyme.

Purpose: Interactions between tear proteins and the interfaces of contact lenses can be complex and can influence contact lens wear success. Tear proteins, including lysozyme, function to maintain the balance of ocular surface homeostasis, as evidenced by the effects of its conformation relative to stabilizing the tear film and its potential impact on corneal epithelial cells. Contact lens manufacturers include components in lens care and blister package solutions to help stabilize the tear film and preserve homeostasis. This in vitro study was performed to evaluate the ability of daily disposable contact lens package solutions to stabilize lysozyme and preserve its native conformation under denaturing conditions. Methods: Lysozyme was added to contact lens solutions sampled from kalifilcon A, etafilcon A, senofilcon A, narafilcon A, nelfilcon A, verofilcon A, delefilcon A, somofilcon A, and stenfilcon A blister packages, then mixed with the protein denaturant sodium lauryl sulfate. Lysozyme activity was evaluated by adding test solutions to a suspension of Micrococcus luteus. Native lysozyme lyses the Micrococcus luteus cell wall, which decreases suspension turbidity. Stabilization of lysozyme activity was determined by comparing suspension turbidity before and after exposure to test solutions. Results: Lysozyme stabilization was 90.7% for kalifilcon A solution, a statistically significant improvement (p < 0.05) compared to phosphate buffered saline (PBS, negative control). No significant improvement was observed with any other contact lens solution (all lysozyme stabilization < 5.00%). Conclusion: The representative tear protein lysozyme was significantly more stable in the novel kalifilcon A contact lens solution containing multiple moisturizers and osmoprotectants than in PBS or other daily disposable contact lens solutions. The lysozyme activity assay provides mechanistic evidence that the kalifilcon A contact lens solution can stabilize proteins under conditions that typically denature proteins, which may contribute to maintaining ocular surface homeostasis.

Correction for Fletcher et al., "Vaccine Potential of the Neisseria meningitidis 2086 Lipoprotein".

[This corrects the article DOI: 10.1128/IAI.72.4.2088-2100.2004.].

Comparative evaluation of multi-purpose solutions in the stabilization of tear lysozyme.

The range and extent of tear proteins removed by various multi-purpose solutions has been investigated, but there is little information in the literature about their ability to prevent denaturation of tear proteins, particularly lysozyme. The purpose of this study was to determine the ability of Bausch+Lomb Biotrue™ multi-purpose solution and other care solutions to affect denaturation of lysozyme using a lysozyme activity assay. The test solutions used were: Biotrue multi-purpose solution, Bausch+Lomb renu(®) fresh™, formerly ReNu MultiPlus(®), Alcon OPTI-FREE RepleniSH, Alcon OPTI-FREE EXPRESS, CIBA VISION AQuify, and AMO COMPLETE Multi-Purpose Solution Easy Rub Formula. A phosphate-buffered saline (PBS) solution served as a control. The test and control solutions containing lysozyme were exposed to sodium dodecyl sulfate (SDS), a known denaturant of the enzyme. The assay was based on digestion of the cell wall of Micrococcus luteus in a suspension, a substrate sensitive to active lysozyme. Enzymatic activity against M. luteus was used to assess activity of lysozyme. The decrease in the turbidity of the cell wall suspension, a measure of relative enzyme activity, was determined by following the decrease in absorbance (at 450nm) over time using a spectrophotometer. Statistically significant greater stabilization of lysozyme was observed with Biotrue multi-purpose solution and renu fresh than with OPTI-FREE RepleniSH, OPTI-FREE EXPRESS, AQuify, COMPLETE Multi-Purpose Solution Easy Rub Formula, and a PBS control. The lysozyme activity assay revealed that Biotrue multi-purpose solution and renu fresh have the ability to stabilize lysozyme under conditions that typically denature the protein.

Intranasal immunization of mice with recombinant lipidated P2086 protein reduces nasal colonization of group B Neisseria meningitidis.

Neisseria meningitidis is a major cause of bacterial meningitis in the human population, especially among young children. There is a need to develop a non-capsular vaccine to prevent meningococcal B infections due to the inadequate immune response elicited against the capsular polysaccharide of these strains. Previously, we developed a Swiss Webster adult mouse intranasal challenge model for group B N. meningitidis and evaluated several potential vaccine candidates including a meningococcal outer membrane protein, P2086, through parenteral immunization. Since N. meningitidis is a respiratory pathogen, a mucosal immune response may play an important role in the defense against meningococcal infections. Thus, intranasal immunization may be more effective than traditional parenteral immunization. In this study, mice were immunized intranasally with purified recombinant lipidated P2086 protein (rLP2086) adjuvanted with either CT-E29H, a genetically modified cholera toxin that is significantly reduced in enzymatic activity and toxicity or RC529-AF, a synthetic immunostimulant molecule in aqueous formulation. rLP2086-specific serum and mucosal IgG and IgA antibodies were induced. IgG antibodies reacted with whole cells of multiple strains of group B N.meningitidis. The antibodies have functional activity against N. meningitidis as demonstrated by bactericidal assays. Moreover, immunized mice exhibited reduced nasal colonization of group B meningococcal strains in the intranasal challenge model. These results demonstrate that an intranasal immunization with rLP2086 protein formulated with a detoxified cholera toxin or RC529-AF could prevent the initial colonization of group B meningococcus and become an effective immunization strategy against group B N. meningitidis.

Evaluation of recombinant lipidated P2086 protein as a vaccine candidate for group B Neisseria meningitidis in a murine nasal challenge model.

Neisseria meningitidis is a major causative agent of bacterial meningitis in human beings, especially among young children (

PppA, a surface-exposed protein of Streptococcus pneumoniae, elicits cross-reactive antibodies that reduce colonization in a murine intranasal immunization and challenge model.

The multivalent pneumococcal conjugate vaccine is effective against both systemic disease and otitis media caused by serotypes contained in the vaccine. However, serotypes not covered by the present conjugate vaccine may still cause pneumococcal disease. To address these serotypes, and the remaining otitis media due to Streptococcus pneumoniae, efforts have been devoted to identifying protective protein antigens. Immunity to conserved surface proteins important for adhesion, nutrient acquisition, or other functions could result in a reduction of colonization and a lower disease potential. We have been searching for conserved surface-exposed proteins from S. pneumoniae that may be involved in pathogenesis to test as vaccine candidates. Here, an approximately 20-kDa protein that has significant homology to a nonheme iron-containing ferritin protein from Listeria innocua and other bactoferritins was identified as pneumococcal protective protein A (PppA). We expressed and purified recombinant PppA (rPppA) and evaluated its potential as a vaccine candidate. The antibodies elicited by purified rPppA were cross-reactive with PppA from multiple strains of S. pneumoniae and were directed against surface-exposed epitopes. Intranasal immunization of BALB/c mice with PppA protein and either a synthetic monophosphoryl lipid A analog, RC529AF, or a cholera toxin mutant, CT-E29H, used as an adjuvant reduced nasopharyngeal colonization in mice following intranasal challenge with a heterologous pneumococcal strain. PppA-specific systemic and local immunoglobulin G (IgG) and IgA antibody responses were induced. The antisera reacted with whole cells of a heterologous S. pneumoniae type 3 strain. These observations indicate that PppA may be a promising candidate for inclusion in a vaccine against pneumococcal otitis media.

Vaccine potential of the Neisseria meningitidis 2086 lipoprotein.

A novel antigen that induces cross-reactive bactericidal antibodies against a number of Neisseria meningitidis strains is described. This antigen, a approximately 28-kDa lipoprotein called LP2086, was first observed within a complex mixture of soluble outer membrane proteins (sOMPs) following a series of fractionation, protein purification, and proteomics steps. Approximately 95 different neisserial isolates tested positive by Western blotting and PCR screening methods for the presence of the protein and the gene encoding LP2086. The strains tested included isolates of N. meningitidis serogroups A, B, C, W135, and Y, Neisseria gonorrhoeae, and Neisseria lactamica. To better understand the microheterogeneity of this protein, the 2086 genes from 63 neisserial isolates were sequenced. Two different subfamilies of LP2086 were identified based on deduced amino acid sequence homology. A high degree of amino acid sequence similarity exists within each 2086 subfamily. The highest degree of genetic diversity was seen between the two subfamilies which share approximately 60 to 75% homology at the nucleic acid level. Flow cytometry (fluorescence-activated cell sorting) analyses and electron microscopy indicated that the LP2086 is localized on the outer surface of N. meningitidis. Antiserum produced against a single protein variant was capable of eliciting bactericidal activity against strains expressing different serosubtype antigens. Combining one recombinant lipidated 2086 (rLP2086) variant from each subfamily with two rPorA variants elicited bactericidal activity against all strains tested. The rLP2086 family of antigens are candidates worthy of further vaccine development.