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Increased SPARC expression in primary angle closure glaucoma iris.

Chua J, Seet LF, Jiang Y, Su R, Htoon HM, Charlton A, Aung T, Wong TT - Mol. Vis. (2008)

Bottom Line: The mean density of iris stromal blood vessels per micron square area was similar in all three groups.SPARC was significantly increased in the PACG iris.The data suggest that SPARC could play a role in the development of PACG by influencing the biomechanical properties of the iris through a change in ECM organization.

View Article: PubMed Central - PubMed

Affiliation: Singapore National Eye Centre, Singapore.

ABSTRACT

Purpose: SPARC (secreted protein, acidic, and rich in cysteine) is involved in extracellular matrix (ECM) organization. The purpose of this study was to evaluate the expression of SPARC in iris tissue from primary angle closure glaucoma (PACG) eyes.

Methods: Iris tissue was obtained from peripheral iridectomies performed during trabeculectomy surgery in nine PACG and 16 primary open-angle glaucoma (POAG) eyes at the Singapore National Eye Centre. Three non-glaucoma control iris specimens were obtained from patients who underwent Descemet's stripping automated endothelial keratoplasty (DSAEK) procedure. SPARC and collagen I expression were quantified by real-time polymerase chain reaction (PCR). The histological distribution of collagen I and III in the iris stroma was determined using picrosirius red polarization. Density of the iris stromal vasculature was also calculated.

Results: The mean age was 68.9+/-10.9 years and 65.7+/-12.2 years in POAG and PACG groups, respectively. The PACG iris expressed SPARC 13.6-fold more and collagen I 5.2 fold more compared to non-glaucoma control iris. The PACG iris also demonstrated 3.3 fold higher SPARC and 2.0 fold higher collagen I expression relative to the POAG iris. The density of collagen I was greater in PACG eyes than in POAG and control eyes (p<0.001). The mean density of iris stromal blood vessels per micron square area was similar in all three groups.

Conclusions: SPARC was significantly increased in the PACG iris. The data suggest that SPARC could play a role in the development of PACG by influencing the biomechanical properties of the iris through a change in ECM organization.

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Related in: MedlinePlus

Analysis of iris sections by Sirius red staining. Iris sections from PACG (A), POAG (B) as well as normal (C) patients were stained with Picrosirius red. When viewed with a polarized light, mature type I collagen fibers appear bright yellow or orange. Magnification x20.
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f2: Analysis of iris sections by Sirius red staining. Iris sections from PACG (A), POAG (B) as well as normal (C) patients were stained with Picrosirius red. When viewed with a polarized light, mature type I collagen fibers appear bright yellow or orange. Magnification x20.

Mentions: Figure 2 shows iris sections stained with picrosirius red stain obtained from PACG, POAG, and non-glaucoma irides. The mean grading for the PACG group was 3.89±0.33 while the mean grading for the POAG group was 2.70±0.52. All three non-glaucoma DSAEK iris specimens demonstrated a grading of 1, which corresponded to the iris grading from a normal fixed eye specimen (data not shown). The difference among the three groups was significant (p<0.001; Table 2) The Bland Altman test showed an excellent agreement of 96% between the two masked independent observers (95% CI 95.9-96.3).


Increased SPARC expression in primary angle closure glaucoma iris.

Chua J, Seet LF, Jiang Y, Su R, Htoon HM, Charlton A, Aung T, Wong TT - Mol. Vis. (2008)

Analysis of iris sections by Sirius red staining. Iris sections from PACG (A), POAG (B) as well as normal (C) patients were stained with Picrosirius red. When viewed with a polarized light, mature type I collagen fibers appear bright yellow or orange. Magnification x20.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2571946&req=5

f2: Analysis of iris sections by Sirius red staining. Iris sections from PACG (A), POAG (B) as well as normal (C) patients were stained with Picrosirius red. When viewed with a polarized light, mature type I collagen fibers appear bright yellow or orange. Magnification x20.
Mentions: Figure 2 shows iris sections stained with picrosirius red stain obtained from PACG, POAG, and non-glaucoma irides. The mean grading for the PACG group was 3.89±0.33 while the mean grading for the POAG group was 2.70±0.52. All three non-glaucoma DSAEK iris specimens demonstrated a grading of 1, which corresponded to the iris grading from a normal fixed eye specimen (data not shown). The difference among the three groups was significant (p<0.001; Table 2) The Bland Altman test showed an excellent agreement of 96% between the two masked independent observers (95% CI 95.9-96.3).

Bottom Line: The mean density of iris stromal blood vessels per micron square area was similar in all three groups.SPARC was significantly increased in the PACG iris.The data suggest that SPARC could play a role in the development of PACG by influencing the biomechanical properties of the iris through a change in ECM organization.

View Article: PubMed Central - PubMed

Affiliation: Singapore National Eye Centre, Singapore.

ABSTRACT

Purpose: SPARC (secreted protein, acidic, and rich in cysteine) is involved in extracellular matrix (ECM) organization. The purpose of this study was to evaluate the expression of SPARC in iris tissue from primary angle closure glaucoma (PACG) eyes.

Methods: Iris tissue was obtained from peripheral iridectomies performed during trabeculectomy surgery in nine PACG and 16 primary open-angle glaucoma (POAG) eyes at the Singapore National Eye Centre. Three non-glaucoma control iris specimens were obtained from patients who underwent Descemet's stripping automated endothelial keratoplasty (DSAEK) procedure. SPARC and collagen I expression were quantified by real-time polymerase chain reaction (PCR). The histological distribution of collagen I and III in the iris stroma was determined using picrosirius red polarization. Density of the iris stromal vasculature was also calculated.

Results: The mean age was 68.9+/-10.9 years and 65.7+/-12.2 years in POAG and PACG groups, respectively. The PACG iris expressed SPARC 13.6-fold more and collagen I 5.2 fold more compared to non-glaucoma control iris. The PACG iris also demonstrated 3.3 fold higher SPARC and 2.0 fold higher collagen I expression relative to the POAG iris. The density of collagen I was greater in PACG eyes than in POAG and control eyes (p<0.001). The mean density of iris stromal blood vessels per micron square area was similar in all three groups.

Conclusions: SPARC was significantly increased in the PACG iris. The data suggest that SPARC could play a role in the development of PACG by influencing the biomechanical properties of the iris through a change in ECM organization.

Show MeSH
Related in: MedlinePlus