Limits...
Clusterin Seals the Ocular Surface Barrier in Mouse Dry Eye.

Bauskar A, Mack WJ, Mauris J, Argüeso P, Heur M, Nagel BA, Kolar GR, Gleave ME, Nakamura T, Kinoshita S, Moradian-Oldak J, Panjwani N, Pflugfelder SC, Wilson MR, Fini ME, Jeong S - PLoS ONE (2015)

Bottom Line: When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress.CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to the galectin LGALS3, a key barrier component.Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure.

View Article: PubMed Central - PubMed

Affiliation: USC Institute for Genetic Medicine and Graduate Program in Medical Biology, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, United States of America.

ABSTRACT
Dry eye is a common disorder caused by inadequate hydration of the ocular surface that results in disruption of barrier function. The homeostatic protein clusterin (CLU) is prominent at fluid-tissue interfaces throughout the body. CLU levels are reduced at the ocular surface in human inflammatory disorders that manifest as severe dry eye, as well as in a preclinical mouse model for desiccating stress that mimics dry eye. Using this mouse model, we show here that CLU prevents and ameliorates ocular surface barrier disruption by a remarkable sealing mechanism dependent on attainment of a critical all-or-none concentration. When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress. CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to the galectin LGALS3, a key barrier component. Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure. These findings define a fundamentally new mechanism for ocular surface protection and suggest CLU as a biotherapeutic for dry eye.

No MeSH data available.


Related in: MedlinePlus

Causal association between endogenous CLU concentration in tears and ocular surface barrier vulnerability.(A) Tears were collected from mice housed under normal ambient conditions or after application of the standard desiccating stress (DS) protocol for 5-days, and ELISA was used to measure CLU concentration (*P = 5x10-8 n = 6, student’s t-test). (B) Representative transmission electron microscopy comparing images of anterior cornea from wild type C57BL6/J mice (A and C) and mice with homozygous CLU-/- knockout on the C57BL6/J background (B and D). In low power (4000x) magnifications (A and B), five layers of epithelial cells divided into squamous, wing, and basal cell regions are visualized along with an intact basement membrane and Bowman's layer in both types of animals. Higher power images (C and D, 20,000x) of similar regions to those boxed in panels A and B show numerous surface microplicae (fat arrows) in both genotypes. Desmosomes (thin arrows) are similar in both frequency and structure. Higher power images (not shown) demonstrate intact adherens junctions in both genotypes. (C) Tears from wild type or heterozygous CLU+/- knockout mice kept at ambient conditions were collected and ELISA was used to measure CLU concentration (p = 2.1x10-5; n = 7, student’s t-test). (D) Wild type mice or heterozygous CLU+/- knockout mice were subjected to the standard desiccating stress protocol, but without scopolamine injection for four weeks and then ocular surface barrier integrity was measured by fluorescein uptake (**p<0.0001, n = 4).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4581869&req=5

pone.0138958.g007: Causal association between endogenous CLU concentration in tears and ocular surface barrier vulnerability.(A) Tears were collected from mice housed under normal ambient conditions or after application of the standard desiccating stress (DS) protocol for 5-days, and ELISA was used to measure CLU concentration (*P = 5x10-8 n = 6, student’s t-test). (B) Representative transmission electron microscopy comparing images of anterior cornea from wild type C57BL6/J mice (A and C) and mice with homozygous CLU-/- knockout on the C57BL6/J background (B and D). In low power (4000x) magnifications (A and B), five layers of epithelial cells divided into squamous, wing, and basal cell regions are visualized along with an intact basement membrane and Bowman's layer in both types of animals. Higher power images (C and D, 20,000x) of similar regions to those boxed in panels A and B show numerous surface microplicae (fat arrows) in both genotypes. Desmosomes (thin arrows) are similar in both frequency and structure. Higher power images (not shown) demonstrate intact adherens junctions in both genotypes. (C) Tears from wild type or heterozygous CLU+/- knockout mice kept at ambient conditions were collected and ELISA was used to measure CLU concentration (p = 2.1x10-5; n = 7, student’s t-test). (D) Wild type mice or heterozygous CLU+/- knockout mice were subjected to the standard desiccating stress protocol, but without scopolamine injection for four weeks and then ocular surface barrier integrity was measured by fluorescein uptake (**p<0.0001, n = 4).

Mentions: The concentration of endogenous CLU in mouse tears was measured using an ELISA. Representative results are shown in Fig 7A. In this experiment, the mean CLU concentration in tears from mice kept at ambient conditions was 5.2±0.4 ug/mL. This was reduced to 3.7±0.3 ug/mL in tears from mice subjected to the 5-day desiccating stress protocol, an ~30% reduction, similar to what was previously observed in the ocular surface epithelium using this mouse model [23].


Clusterin Seals the Ocular Surface Barrier in Mouse Dry Eye.

Bauskar A, Mack WJ, Mauris J, Argüeso P, Heur M, Nagel BA, Kolar GR, Gleave ME, Nakamura T, Kinoshita S, Moradian-Oldak J, Panjwani N, Pflugfelder SC, Wilson MR, Fini ME, Jeong S - PLoS ONE (2015)

Causal association between endogenous CLU concentration in tears and ocular surface barrier vulnerability.(A) Tears were collected from mice housed under normal ambient conditions or after application of the standard desiccating stress (DS) protocol for 5-days, and ELISA was used to measure CLU concentration (*P = 5x10-8 n = 6, student’s t-test). (B) Representative transmission electron microscopy comparing images of anterior cornea from wild type C57BL6/J mice (A and C) and mice with homozygous CLU-/- knockout on the C57BL6/J background (B and D). In low power (4000x) magnifications (A and B), five layers of epithelial cells divided into squamous, wing, and basal cell regions are visualized along with an intact basement membrane and Bowman's layer in both types of animals. Higher power images (C and D, 20,000x) of similar regions to those boxed in panels A and B show numerous surface microplicae (fat arrows) in both genotypes. Desmosomes (thin arrows) are similar in both frequency and structure. Higher power images (not shown) demonstrate intact adherens junctions in both genotypes. (C) Tears from wild type or heterozygous CLU+/- knockout mice kept at ambient conditions were collected and ELISA was used to measure CLU concentration (p = 2.1x10-5; n = 7, student’s t-test). (D) Wild type mice or heterozygous CLU+/- knockout mice were subjected to the standard desiccating stress protocol, but without scopolamine injection for four weeks and then ocular surface barrier integrity was measured by fluorescein uptake (**p<0.0001, n = 4).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581869&req=5

pone.0138958.g007: Causal association between endogenous CLU concentration in tears and ocular surface barrier vulnerability.(A) Tears were collected from mice housed under normal ambient conditions or after application of the standard desiccating stress (DS) protocol for 5-days, and ELISA was used to measure CLU concentration (*P = 5x10-8 n = 6, student’s t-test). (B) Representative transmission electron microscopy comparing images of anterior cornea from wild type C57BL6/J mice (A and C) and mice with homozygous CLU-/- knockout on the C57BL6/J background (B and D). In low power (4000x) magnifications (A and B), five layers of epithelial cells divided into squamous, wing, and basal cell regions are visualized along with an intact basement membrane and Bowman's layer in both types of animals. Higher power images (C and D, 20,000x) of similar regions to those boxed in panels A and B show numerous surface microplicae (fat arrows) in both genotypes. Desmosomes (thin arrows) are similar in both frequency and structure. Higher power images (not shown) demonstrate intact adherens junctions in both genotypes. (C) Tears from wild type or heterozygous CLU+/- knockout mice kept at ambient conditions were collected and ELISA was used to measure CLU concentration (p = 2.1x10-5; n = 7, student’s t-test). (D) Wild type mice or heterozygous CLU+/- knockout mice were subjected to the standard desiccating stress protocol, but without scopolamine injection for four weeks and then ocular surface barrier integrity was measured by fluorescein uptake (**p<0.0001, n = 4).
Mentions: The concentration of endogenous CLU in mouse tears was measured using an ELISA. Representative results are shown in Fig 7A. In this experiment, the mean CLU concentration in tears from mice kept at ambient conditions was 5.2±0.4 ug/mL. This was reduced to 3.7±0.3 ug/mL in tears from mice subjected to the 5-day desiccating stress protocol, an ~30% reduction, similar to what was previously observed in the ocular surface epithelium using this mouse model [23].

Bottom Line: When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress.CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to the galectin LGALS3, a key barrier component.Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure.

View Article: PubMed Central - PubMed

Affiliation: USC Institute for Genetic Medicine and Graduate Program in Medical Biology, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, United States of America.

ABSTRACT
Dry eye is a common disorder caused by inadequate hydration of the ocular surface that results in disruption of barrier function. The homeostatic protein clusterin (CLU) is prominent at fluid-tissue interfaces throughout the body. CLU levels are reduced at the ocular surface in human inflammatory disorders that manifest as severe dry eye, as well as in a preclinical mouse model for desiccating stress that mimics dry eye. Using this mouse model, we show here that CLU prevents and ameliorates ocular surface barrier disruption by a remarkable sealing mechanism dependent on attainment of a critical all-or-none concentration. When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress. CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to the galectin LGALS3, a key barrier component. Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure. These findings define a fundamentally new mechanism for ocular surface protection and suggest CLU as a biotherapeutic for dry eye.

No MeSH data available.


Related in: MedlinePlus