The effect of levocabastine hydrochloride on human Tenon’s capsule fibroblasts: Inhibition of proliferation, suppression of DNA synthesis and induction of apoptosis

Modulation of Fibroblasts in Conjunctival Wound Healing

Modulating conjunctival wound healing has the potential to improve outcomes after glaucoma filtration surgery and for several ocular disorders, including ocular cicatrial pemphigoid, vernal keratoconjunctivitis, and pterygium. Although anti-inflammatories and antimetabolites have been used with success, these nonspecific agents are not without their complications. The search for novel and more targeted means to control conjunctival fibrosis without such limitations has brought much attention to the regulation of fibroblast proliferation, differentiation, extracellular matrix production, and apoptosis. This review provides an update on where we stand with current antifibrotic agents and outlines the strategies that novel agents use, as they evolve from the bench to the bedside.

The role of histamine in the regulation of the viability, proliferation and transforming growth factor β1 secretion of rat wound fibroblasts

BACKGROUND

Inflammation mediators play a regulatory role in repair processes. The study will examine the influence of histamine on wound fibroblast metabolic activity, viability, proliferation, and TGFβ1 secretion. The study also will identify the histamine receptor involved in regulation of the tested repair processes.

METHODS

Fibroblasts were obtained from the granulation tissue of wounds or intact dermis of rats. The MTT and BrdU assays were used to examine the effect of histamine (10^-8M-10^-4M) on the viability and metabolic activity of fibroblasts, and on their proliferative capacity. The influence of histamine receptor antagonists (i.e., ketotifen, ranitidine, ciproxifan and JNJ7777120) and agonists (2-pyridylethlamine dihydrochloride, amthamine dihydrobromide) was also investigated. The TGFβ1 and histamine receptors H1 were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Histamine significantly increased granulation tissue fibroblast viability and metabolic activity at 10^-8 and 10^-6M but did not change their proliferative activity. Only the blockade of the H1 receptor removed this effect of histamine. H1 receptor agonist (2-pyridylethlamine dihydrochloride) increased cell viability, thereby mimicking histamine action. Both Histamine (10^-4M) and 2-pyridylethlamine dihydrochloride increased TGFβ1 concentration in cell culture medium. However, ketotifen blocked histamine-induced augmentation of TGFβ1. H1 receptor expression on wound fibroblasts was confirmed.

CONCLUSION

The regulatory influence of histamine on wound fibroblast function (viability/metabolic activity or secretion of TGFβ1) is dependent on H1 receptor stimulation. Contrary to wound fibroblasts, these cells express a very low level of H1 receptors when isolated from intact dermis and histamine is unable to modify their metabolic activity.

Functional characteristics of connective tissue growth factor on human tenon's capsule fibroblast

PURPOSE OF THE STUDY

To explore the characteristic of connective tissue growth factor (CTGF) on the phenotype transition, extracellular matrix (ECM) synthesis and proliferation of human Tenon's capsule fibroblasts (HTFs).

MATERIALS AND METHODS

HTFs were obtained from patients during cataract surgery and induced by CTGF (1 to 100 µg/L). Western blot and immunofluorescence were performed to observe the expression of alpha smooth muscle actin (α-SM-actin) protein. The levels of mRNAs were quantified by real-time PCR. Col I and FN expression at both protein and RNA levels were tested after induction by CTGF and transforming growth factor β (TGF-β), respectively. Statistical significance was assumed if p < 0.05.

RESULTS

CTGF upregulated the expression of α-SM-actin in cultured HTFs. Its maximum effect at protein level attained under the optimal concentration of 50 μg/L at the peak time of 48 hours, though still weaker than the effect of TGF-β1 (10 μg/L, p < 0.05). The expression of Col I and FN at both protein and mRNA levels was elevated by the induction of CTGF (50 μg/L) (p < 0.01) and TGF-β1 (10 μg/L) (p < 0.05), while CTGF (50 μg/L) showed a greater effect than the latter (p < 0.05). CTGF (1 to100 μg/L) increased the proliferation of HTFs significantly (p < 0.05).

CONCLUSIONS

CTGF induced the phenotype transition of HTFs individually and significantly promoted their proliferation. Moreover, it promoted ECM synthesis, thus demonstrating its role as a crucial factor in fibrosis. Thus, CTGF could potentially be a safer and more efficient target than TGF-β at suppressing scar formation after filtering surgery.