lactoferrin and Keratitis

The surface of the eye provides an inert barrier against infection. Through its unique combination of antimicrobial action and anti-inflammatory activities lactoferrin (Lf) in the tear film plays an important role in the maintenance of ocular health. In order to maintain clarity the eye must provide immunological defense without immunopathology. Along with physical barriers, soluble plasma factors and other proteins such as lysozyme, Lf produced by the acinar cells of the lacrimal gland serves a number of roles in defense for this purpose. Lf in tears provides antimicrobial efficacy by binding free iron thus reducing the availability of iron necessary for microbial growth and survival as well as pathogenesis. Lf has been shown to inhibit biofilm formation and thus may play a role in protecting contact lens surfaces from colonization. Virus particles' entry into epithelial cells is inhibited by Lf while an excess of Lf in tear film is thought to limit the opportunistic Lf-mediated bridging of adenovirus and host cell that occurs in other tissues. Lf dampens the classical complement activation pathway by binding to markers of inflammation and immune activation while pathogen-associated molecular patterns such as lipopolysaccharide (LPS) are targeted by Lf for removal through tears and hydrodynamic flushing. This review focuses on the role of Lf in human tear film and its contribution to ocular health during contact lens wear.

Topics: Animals; Biofilms; Humans; Keratitis; Lactoferrin; Tears

The human eye is constantly bathed by tears, which protect the ocular surface via a variety of mechanisms. The O-linked glycans of tear mucins have long been considered to play a role in binding to pathogens and facilitating their removal in the tear flow. Other conjugated glycans in tears could similarly contribute to pathogen binding and removal but have received less attention. In the work presented here we assessed the contribution of glycan moieties, in particular the protein attached N-glycans, presented by the broad complement of tear proteins to the adhesion of the opportunistic pathogen Pseudomonas aeruginosa, a leading cause of microbial keratitis and ulceration of the cornea. Our adhesion assay involved immobilising the macromolecular components of tears into the wells of a polyvinyl difluoride (PVDF) microtitre filter plate and probing the binding of fluorescently labelled bacteria. Three P. aeruginosa strains were studied: a cytotoxic strain (6206) and an invasive strain (6294) from eye infections, and an invasive strain (320) from a urinary tract infection (UTI). The ocular isolates adhered two to three times more to human tears than to human saliva or porcine gastric mucin, suggesting ocular niche-specific adaptation. Support for the role of the N-glycans carried by human tear proteins in the binding and removal of P. aeruginosa from the eye was shown by: 1) pre-incubation of the bacteria with free component sugars, galactose, mannose, fucose and sialyl lactose (or combination thereof) inhibiting adhesion of all the P. aeruginosa strains to the immobilised tear proteins, with the greatest inhibition of binding of the ocular cytotoxic 6206 and least for the invasive 6294 strain; 2) pre-incubation of the bacteria with N-glycans released from the commercially available human milk lactoferrin, an abundant protein that carries N-linked glycans in tears, inhibiting the adhesion to tears of the ocular bacteria by up to 70%, which was significantly more binding inhibition than by the same amount of intact human lactoferrin or by the plant-derived N-glycans released from the rice recombinant lactoferrin; 3) pre-incubation of the bacteria with N-linked glycans released from human tear proteins inhibiting the adhesion of the ocular P. aeruginosa strains to immobilised tear proteins; 4) inhibition by the N-glycans from lactoferrin of the ability of an ocular strain of P. aeruginosa to invade corneal epithelial cells; 5) removal of terminal sialic acid

Topics: Analysis of Variance; Animals; Bacterial Adhesion; Cornea; Epithelial Cells; Epithelium, Corneal; Eye Infections, Bacterial; Eye Proteins; Glycoproteins; Humans; Keratitis; Lactoferrin; Lectins; Mucins; Polysaccharides; Pseudomonas aeruginosa; Swine; Tears

Biofilms are considered as the most important developmental characteristics in ocular infections. Biofilm eradication is a major challenge today to overcome the incidence of drug resistance. This report demonstrates the in vitro ability of biofilm formation on contact lens by three common keratitis-associated fungal pathogens, namely, Aspergillus fumigatus, Fusarium solani, and Candida albicans. Antifungal sensitivity testing performed for both planktonic cells and biofilm revealed the sessile phenotype to be resistant at MIC levels for the planktonic cells and also at higher concentrations. A prototype lens care solution was also found to be partially effective in eradication of the mature biofilm from contact lenses. Lactoferricin B (Lacf, 64 μg/ml), an antimicrobial peptide, exhibited almost no effect on the sessile phenotype. However, the combinatory effect of Lacf with antifungals against planktonic cells and biofilms of three fungal strains that were isolated from keratitis patients exhibited a reduction of antifungal dose more than eightfold. Furthermore, the effect of Lacf in lens care solution against biofilms in which those strains formed was eradicated successfully. These results suggest that lactoferricin B could be a promising candidate for clinical use in improving biofilm susceptibility to antifungals and also as an antibiofilm-antifungal additive in lens care solution.

Topics: Amino Acid Sequence; Antifungal Agents; Biofilms; Contact Lens Solutions; Contact Lenses; Eye Infections, Fungal; Humans; Keratitis; Lactoferrin; Microbial Sensitivity Tests; Microscopy, Fluorescence; Mitosporic Fungi; Molecular Sequence Data; Phenotype

To determine whether intolerance to contact lens wear is attributable to clinical or protein characteristics of the tear film.. Thirty-eight subjects participated; 20 were successful contact lens wearers and 18 had discontinued contact lens wear because of discomfort. Baseline tear film (no lens wear) was analyzed with a range of clinical measurements and protein analyses (lactoferrin, sIgA, and lysozyme). Comfort was determined after 6 hours of lens wear, and differences in tear film characteristics between subject groups were determined. In half of the subject group (n = 19), discriminant analysis was used to develop an equation for predicting the likelihood of intolerance to lens wear. Sensitivity and specificity were determined by testing the formula on the remaining subjects. These formulas were also tested on a separate group of subjects enrolled in a contact lens-wearing trial.. Tear volume (meniscus height and phenol red thread test) and tear stability (noninvasive tear break up time [NI-TBUT]) were significantly reduced in intolerant wearers (P < 0.05). A greater number of symptoms were reported by intolerant than by tolerant wearers (P < 0.05). Tolerance was associated with clinical but not protein characteristics of the tear film. Formulas best able to predict contact lens intolerance included NI-TBUT, number of symptoms experienced, and tear film meniscus height. Formulas had high sensitivity, and specificity which ranged from 29% to 57%.. Contact lens intolerance appears to be best predicted by a combination of clinical variables, including tear film stability, tear volume, and symptom reporting.

Topics: Adult; Conjunctivitis; Contact Lenses; Discriminant Analysis; Dry Eye Syndromes; Eye Proteins; Female; Humans; Immunoglobulin A, Secretory; Keratitis; Lactoferrin; Male; Muramidase; Osmolar Concentration; Patient Satisfaction; Phenolsulfonphthalein; Sensitivity and Specificity; Tears

Lactoferrin supplementation suppresses ultraviolet light B (UV-B)-induced oxidation of cultures of human corneal epithelial cells. To investigate the protective effect of lactoferrin containing eyedrops against UV-B-induced corneal damage in vivo, we examined lactoferrin efficacy in a rat UV-B keratitis model.. Sprague-Dawley rats were irradiated with >10 kJ/m2 after anesthetization, and then corneal epithelial defect was observed at 24 h postirradiation. The pre- or postapplication of vehicle or lactoferrin-containing eyedrops was performed, and then corneal epithelial damage was scored based on fluorescein staining.. Posttreatment with lactoferrin did not inhibit the extent of corneal damage and did not affect wound healing. However, pretreatment by topical application of lactoferrin suppressed development of a corneal epithelial defect induced by UV-B irradiation in rats.. These results suggest that the presence of lactoferrin in human tear fluid may inhibit UV-induced corneal epithelial damage.

Topics: Animals; Epithelium, Corneal; Keratitis; Lactoferrin; Male; Ophthalmic Solutions; Radiation Injuries, Experimental; Rats; Rats, Sprague-Dawley; Ultraviolet Rays