Recombinant TIMP-1 and -2 enhance the proliferation of rabbit corneal epithelial cells in vitro and the spreading of rabbit corneal epithelium in situ

The Effect of Tissue Inhibitor of Metalloproteinases on Scar Formation after Spinal Cord Injury

Spinal cord injury (SCI) often results in permanent loss of motor and sensory function. After SCI, the blood-spinal cord barrier (BSCB) is disrupted, causing the infiltration of neutrophils and macrophages, which secrete several kinds of cytokines, as well as matrix metalloproteinases (MMPs). MMPs are proteases capable of degrading various extracellular matrix (ECM) proteins, as well as many non-matrix substrates. The tissue inhibitor of MMPs (TIMP)-1 is significantly upregulated post-SCI and operates via MMP-dependent and MMP-independent pathways. Through the MMP-dependent pathway, TIMP-1 directly reduces inflammation and destruction of the ECM by binding and blocking the catalytic domains of MMPs. Thus, TIMP-1 helps preserve the BSCB and reduces immune cell infiltration. The MMP-independent pathway involves TIMP-1's cytokine-like functions, in which it binds specific TIMP surface receptors. Through receptor binding, TIMP-1 can stimulate the proliferation of several types of cells, including keratinocytes, aortic smooth muscle cells, skin epithelial cells, corneal epithelial cells, and astrocytes. TIMP-1 induces astrocyte proliferation, modulates microglia activation, and increases myelination and neurite extension in the central nervous system (CNS). In addition, TIMP-1 also regulates apoptosis and promotes cell survival through direct signaling. This review provides a comprehensive assessment of TIMP-1, specifically regarding its contribution to inflammation, ECM remodeling, and scar formation after SCI.

Integrated Analysis of Transcriptome and Proteome of the Human Cornea and Aqueous Humor Reveal Novel Biomarkers for Corneal Endothelial Cell Dysfunction

Earlier studies have reported that elevated protein levels in the aqueous humor (AH) are associated with corneal endothelial cell dysfunction (CECD), but the details of the underlying mechanism as well as specific biomarkers for CECD remain elusive. In the present study, we aimed to identify protein markers in AH directly associated with changes to corneal endothelial cells (CECs), as AH can be easily obtained for analysis. We carried out an in-depth proteomic analysis of patient-derived AH as well as transcriptomic analysis of CECs from the same patients with bullous keratopathy (BK) resulting from CECD. We first determined differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) from CECs and AH in CECD, respectively. By combining transcriptomic and proteomic analyses, 13 shared upregulated markers and 22 shared downregulated markers were observed between DEGs and DEPs. Among these 35 candidates from biomarker profiling, three upregulated markers were finally verified via data-independent acquisition (DIA) proteomic analysis using additional individual AH samples, namely metallopeptidase inhibitor 1 (TIMP1), Fc fragment of IgG binding protein (FCGBP), and angiopoietin-related protein 7 (ANGPTL7). Furthermore, we confirmed these AH biomarkers for CECD using individual immunoassay validation. Conclusively, our findings may provide valuable insights into the disease process and identify biofluid markers for the assessment of CEC function during BK development.

Exploratory Phase II Multicenter, Open-Label, Clinical Trial of ST266, a Novel Secretome for Treatment of Persistent Corneal Epithelial Defects

Objective

An exploratory phase II, multicenter, open-label, clinical trial (NCT03687632) was conducted to evaluate the safety and effectiveness in treating persistent corneal epithelial defects (PEDs) with ST266, a proprietary novel multi-cytokine platform biologic solution secreted by cultured Amnion-derived Multipotent Progenitor (AMP) cells.

Methods

Subjects with a PED were treated with ST266 eye drops 4 times daily for 28 days, then followed for 1 week. Safety was assessed by monitoring of adverse events (AEs) and serious adverse events (SAEs). Efficacy was assessed by measuring the area of the PED by slit lamp biomicroscopy. Tolerability of ST266, percentage of eyes with complete healing, reduction in area of the epithelial defect, and maintenance of a reduction in the area of the epithelial defect 7 days after treatment were recorded.

Results

Thirteen patients were enrolled into the trial at one of eight sites. The first patient withdrew after 5 days. The remaining 12 patients with PEDs with median duration of 39 days (range = 12 to 393 days) completed treatment. Ten of the 12 eyes had been refractory to treatment with various conventional therapies prior to enrollment. After 28 days of treatment, there was a significant decrease in mean PED area compared with baseline (66.4% ± 35.3%, P = 0.001). At follow-up, 1 week after completion of treatment, on day 35, the PED area was further reduced by 78.8% ± 37.5% (P = 0.01) compared with baseline. During 28 days of treatment, 5 eyes (41.7%) had complete wound closure. There were no AEs of concern thought to be related to the drug, and no SAEs were noted.

Conclusions

In this trial, we found ST266 eye drops might promote corneal epithelization, thereby reducing the PED area, including in refractory cases in a wide range of etiologies. ST266 was well-tolerated by most patients.

Neurogenic differentiation factor NeuroD confers protection against radiation-induced intestinal injury in mice

The gastrointestinal tract, especially the small intestine, is particularly sensitive to radiation, and is prone to radiation-induced injury as a result. Neurogenic differentiation factor (NeuroD) is an evolutionarily-conserved basic helix-loop-helix (bHLH) transcription factor. NeuroD contains a protein transduction domain (PTD), which allows it to be exogenously delivered across the membrane of mammalian cells, whereupon its transcription activity can be unleashed. Whether NeuroD has therapeutic effects for radiation-induced injury remains unclear. In the present study, we prepared a NeuroD-EGFP recombinant protein, and explored its protective effects on the survival and intestinal damage induced by ionizing radiation. Our results showed that NeuroD-EGFP could be transduced into small intestine epithelial cells and tissues. NeuroD-EGFP administration significantly increased overall survival of mice exposed to lethal total body irradiation (TBI). This recombinant NeuroD also reduced radiation-induced intestinal mucosal injury and apoptosis, and improved crypt survival. Expression profiling of NeuroD-EGFP-treated mice revealed upregulation of tissue inhibitor of metalloproteinase 1 (TIMP-1), a known inhibitor of apoptosis in mammalian cells. In conclusion, NeuroD confers protection against radiation-induced intestinal injury, and provides a novel therapeutic clinical option for the prevention of intestinal side effects of radiotherapy and the treatment of victims of incidental exposure.

Cytokine functions of TIMP-1

The tissue inhibitors of metalloproteinases (TIMPs) are well recognized for their role in extracellular matrix remodeling by controlling the activity of matrix metalloproteinases (MMPs). Independent of MMP inhibition, TIMPs act as signaling molecules with cytokine-like activities thereby influencing various biological processes including cell growth, apoptosis, differentiation, angiogenesis, and oncogenesis. Recent studies on TIMP-1's cytokine functions have identified complex regulatory networks involving a specific surface receptor and subsequent signaling pathways including miRNA-mediated posttranscriptional regulation of gene expression that ultimately control the fate and behavior of the cells. The present review summarizes the current knowledge on TIMP-1 as a cytokine modulator of cell functions, outlines recent progress in defining molecular pathways that transmit TIMP-1 signals from the cell periphery into the nucleus, and discusses TIMP-1's role as a cytokine in the pathophysiology of cancer and other human diseases.

Altered expression of matrix metalloproteinases and their tissue inhibitors as possible contributors to corneal droplet formation in climatic droplet keratopathy

PURPOSE

Climatic droplet keratopathy (CDK) is an acquired corneal disease characterized by progressive scarring of the cornea. In several corneal diseases, matrix metalloproteinases (MMPs) are upregulated during the degradation of epithelial and stromal tissues. We investigated the levels, degree of activation and molecular forms of MMP-2, MMP-9, MMP-8 and MMP-13 and their tissue inhibitors TIMP-1 and TIMP-2 in tear fluid of patients with CDK.

METHODS

Seventeen CDK patients and 10 controls living in Argentine Patagonia received a complete eye examination, and MMPs and TIMP-1/2 were determined by immunofluorometric assay (IFMA), gelatin zymography and quantitative Western immunoblot analysis in tear samples.

RESULTS

The MMPs were detected mostly in their latent forms. The levels of MMP-9 and MMP-2 were found to be significantly elevated in CDK patients, whereas latent and active MMP-8 levels were significantly enhanced in controls. There was no significant difference in the level of MMP-13. TIMPs were found as part of complexes, and the TIMP-1 levels were significantly lower in patients than controls.

CONCLUSION

Elevated MMP-2 and MMP-9 levels have been implicated in the failure of corneal re-epithelialization, and enhanced MMP-2 and MMP-9 levels in CDK patients suggest that these MMPs may play a role in corneal scarring in CDK. Elevated levels of MMP-8 suggest a defensive role for this MMP in inflammatory reactions associated with recurring corneal traumas. Decreased expression of TIMP-1 in CDK patients suggest deficient antiproteolytic shield likely to render the corneas of CDK patients vulnerable to enhanced MMPs. Overall, these data suggest a mechanistic link between MMPs and TIMP-1 level in cornea and tears with corneal scarring in CDK.

Tissue inhibitor of metalloproteinase-1 promotes NIH3T3 fibroblast proliferation by activating p-Akt and cell cycle progression

Tissue inhibitor of metalloproteinase-1 (TIMP-1) plays various roles in cell growth in different cell types. However, few studies have focused on TIMP-1's effect on fibroblast cells. In this study, we investigated the effects of TIMP-1 overexpression on NIH3T3 fibroblast proliferation and potential transduction signaling pathways involved. Overexpression of TIMP-1, by transfection of the pLenti6/V5-DESTTIMP-1 plasmid, significantly promoted NIH3T3 proliferation as determined by the BrdU array. Neither 5 nor 15 nM GM6001 (matrix metalloproteinase system inhibitor) affected NIH3T3 proliferation, but 45 nM GM6001 inhibited proliferation. TIMP-1 overexpression activated the p-Akt pathway, but not the p-ERK or p-p38 pathway. In TIMP-1-transfected cells, cyclinD1 was upregulated and p21CIP1 and p27(KIP1) were downregulated, which promoted cell entry into the S and G2/M phases. The PI3-K inhibitor LY294002 abolished the TIMP-1-induced effects. Overexpression of intracellular TIMP-1 stimulated NIH3T3 fibroblast proliferation in a matrix metalloproteinase (MMP)-independent manner by activating the p-Akt pathway and related cell cycle progression.

[The role of matrix metalloproteinases and tissue inhibitors of metalloproteinases in invasion of tumours of neuroepithelial tissue]

Tumour invasion requires degradation of extracellular matrix components and migration of cells through degraded structures into surrounding tissues. Matrix metalloproteinases (MMP) constitute a family of zinc and calcium-dependent endopeptidases that play a key role in the breakdown of extracellular matrix, and in processing of cytokines, growth factors, chemokines and cell surface receptors. Their activity is regulated at the levels of transcription, activation and inhibition by tissue inhibitors of metalloproteinases (TIMP). Changes in expression of MMP and TIMP are implicated in tumour invasion, because they may contribute to both migration of tumour cells and angiogenesis. Alterations of MMP expression observed in brain tumours arouse interest in the development and evaluation of synthetic matrix metalloproteinase inhibitors as antitumour agents.

TIMPs as multifacial proteins

Tissue inhibitors of metalloproteinases (TIMPs) are natural inhibitors of matrix metalloproteinases (MMPs) found in most tissues and body fluids. By inhibiting MMPs activities, they participate in tissue remodeling of the extracellular matrix (ECM). The balance between MMPs and TIMPs activities is involved in both normal and pathological events such as wound healing, tissue remodeling, angiogenesis, invasion, tumorigenesis and metastasis. The intracellular signalling controlling both TIMPs and MMPs expression begins to be elucidated and gaining insights into the molecular mechanisms regulated by TIMPs and MMPs could represent a new approach in the development of potential therapeutics. Numerous investigations have pointed out that TIMPs exhibit multifunctional activities distinct from MMP inhibition. In this review, we detailed the multiple activities of TIMPs in vivo and in vitro and we reported their implication in physiological and pathological processes. Further, we documented recent studies of their role in hematopoiesis and we itemized the different signalling pathways they induced.

TIMP-1 role in protection against Pseudomonas aeruginosa-induced corneal destruction

To establish the role of TIMP-1 in protection against Pseudomonas aeruginosa-induced corneal destruction, corneas of adult 8-week-old (resistant) and aged 12-month-old (susceptible) mice were infected with the bacterium. Corneas were analyzed for TIMP-1 protein by immunocytochemistry and Western blotting. Basement membrane (BM) integrity was assessed by immunostaining for type IV collagen. Additionally, resistant 8-week-old mice were treated systemically with neutralizing TIMP-1 polyclonal antibody (pAb) or pre-immune normal rabbit serum (NRS). Ocular and BM integrity as well as MMP-9 expression were examined in these mice. A greater amount of TIMP-1 protein was observed in the cornea of 8-week-old mice. In the cornea, the strongest staining was found in the superficial epithelium, but positive staining also was seen in the basal epithelium and stroma. When type IV collagen was analyzed in the BM of both age groups of mice, a distinct staining pattern was observed in only the young adult mice. Treatment of 8-week-old resistant mice with neutralizing TIMP-1 pAb vs NRS increased the amount of MMP-9 in the cornea of TIMP-1 pAb-treated mice and affected the ability of these mice to deposit BM components. These studies suggest that adequate expression of TIMP-1 protects against BM and stromal degradation via multiple processes.

Matrix metalloproteinases (MMP-2 and 9) and tissue inhibitors of matrix metalloproteinases (TIMP-1 and 2) during the course of experimental necrotizing herpetic keratitis

To determine the distribution and activities of metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) during the course of experimental herpes simplex virus (HSV) type-1 keratitis, BALB/c mice were corneally infected with 10(5) plaque-forming units (PFU) of HSV-1 (KOS strain) and then observed for the clinical signs of keratitis. Corneas were harvested at days 0, 2, 7 and 14 post-infection (p.i.). MMP-2, MMP-9, MMP-8, TIMP-1 and TIMP-2 were detected by immunohistochemistry and the Western blot technique. The enzymatic activities were analyzed by zymography. Epithelial HSV keratitis was present at day 2 after corneal infection and healed by day 5 p.i. While the expression and activity of MMP-2, MMP-8 and MMP-9 increased in the corneas at day 2 p.i., it was reduced at day 7 p.i. TIMP-1 and -2 were expressed in the corneas before and seven days after infection. Necrotizing stromal keratitis with corneal ulceration and dense polymorphonuclear leukocyte (PMN) infiltration was present at day 14 p.i. This correlated with increased expression of MMP-2, MMP-8 and MMP-9 in the corneas. MMP-8, MMP-9 and MMP-2 staining was particularly intense in the proximity of the ulcers and in areas of PMN infiltration. At day 14 p.i., MMP-2, -8 and -9 activities were upregulated, and TIMP-2 was expressed. These data suggest that MMPs produced by resident corneal cells and PMNs may possibly play a role in early epithelial keratitis and in the ulcerative process in the late phase after corneal HSV-1 infection. The ratio of MMPs to TIMPs may be important for the course of necrotizing HSV keratitis. TIMPs might participate in the repair process.

Epithelial repair: roles of extracellular matrix

PURPOSE

To review studies of the roles of extracellular matrix (ECM) metabolism in corneal epithelium during wound repair. Methods. 1) Alterations in the structure and composition of epithelial basement membrane during corneal epithelial healing were examined histologically and immunohistochemically. 2) The effects of procollagen and hyaluronan synthesis inhibitors on the spread of rabbit corneal epithelium were determined in organ culture. 3) Expression of keratan sulfate proteoglycan (KSPG) proteins in corneal epithelium was examined during repair after injury in wild-type and lumican-null mice.

RESULTS

1) Corneal epithelial basement membrane was transiently degraded and reassembled during tissue repair. Patterns of type IV collagen immunoreactivity were also transiently altered. The system of matrix metalloproteinase-tissue inhibitors of metalloproteinases may play an important role in the disassembly and reorganization of epithelial basement membrane. 2) Inhibitors of procollagen secretion and hyaluronan biosynthesis disrupted the spread of a corneal epithelial sheet in situ. 3) Among the corneal KSPG proteins examined, lumican was transiently expressed in migrating murine corneal epithelial cells. Anti-lumican antibody inhibited corneal epithelial resurfacing in organ culture. The absence of lumican was found to delay corneal epithelial wound healing in mice.

CONCLUSION

Extracellular matrix metabolism by the injured corneal epithelium is important in the repair process.

Simple organ cornea culture model for re-epithelialization after in vitro excimer laser ablation

BACKGROUND AND OBJECTIVE

Most of the in vitro work to characterize the effects of clinical laser surgery on corneal tissues has concentrated on the effects on stromal keratocytes and endothelium with little attention being paid to corneal epithelium. Our purpose is to describe the epithelial healing rates observed in freshly cultured rabbit corneas treated with phototherapeutic keratectomy (PTK).

STUDY DESIGN/MATERIALS AND METHODS

Corneas were placed in a simple organ culture system, with media change every 2 days. A clinical excimer laser was used to perform a 6 mm diameter, 100 microm depth transepithelial PTK on 24 cultured rabbit corneas, 1 day after culture initiation. For each post-treatment day, one experimental and one control cornea were removed from culture and stained with fluorescein, photographed, and fixed for histology. Epithelial defect area was measured with digital imaging software and analyzed statistically to assess the re-epithelialization rate.

RESULTS

Control corneas, maintained in culture for 1-4 days, had no epithelial defects. Those corneas treated with PTK exhibited an immediate epithelial defect that slowly healed over 3 days. This was confirmed on histopathological analysis. A significant linear trend in re-epithelialization across the time points studied was found (F = 80.48, P = 0.0029). The slope of the linear regression model showed an estimate rate of re-epithelialization of -6.70 over the 3 days.

CONCLUSION

We have described the development of a simple, whole organ, rabbit cornea culture model for re-epithelialization after PTK. Our rates of epithelial healing resemble those found in the literature in live rabbit models. Therefore, this model may possibly be used to monitor epithelial wound healing in different corneal diseases or injuries.

Tissue inhibitor of metalloproteinases 1 and 2 directly stimulate the bone-resorbing activity of isolated mature osteoclasts

Tissue inhibitor metalloproteinases 1 (TIMP-1) and 2 have been reported to inhibit bone resorption. However, here, we report the direct action of both TIMP-1 and TIMP-2 on isolated rabbit mature osteoclasts to stimulate their bone-resorbing activity at significantly lower concentrations (approximately ng/ml) than those (approximately microg/ml) required for the inhibition of bone resorption. The cell population used in this study consisted of a mature osteoclast population with >95% purity. TIMP-1 (approximately 50 ng/ml) and TIMP-2 (approximately 8-10 ng/ml) increased the pit area excavated by the isolated mature osteoclasts. The stimulatory effects of TIMPs were abolished by simultaneous addition of anti-TIMP antibodies. At higher concentrations, the stimulation of bone resorption decreased reversely to the control level. The magnitude of the stimulatory effect of TIMP-2 was more than that of TIMP-1. Metalloproteinase inhibitors such as BE16627B and R94138 could not replace TIMPs with respect to the bone-resorbing activity, suggesting that the osteoclast-stimulating activity of TIMPs was independent of the inhibitory activity on matrix metalloproteinases (MMPs). TIMPs stimulated tyrosine phosphorylation of cellular proteins in the isolated mature osteoclasts. Both herbimycin A, an inhibitor of tyrosine kinases, and PD98059 and U0126, inhibitors of mitogen-activated protein kinase (MAPK), completely blocked the TIMP-induced stimulation of osteoclastic bone-resorbing activity. On the plasma membrane of osteoclasts, some TIMP-2-binding proteins were detected by a cross-linking experiment. These findings show that TIMPs directly stimulate the bone-resorbing activity of isolated mature osteoclasts at their physiological concentrations and that the stimulatory action of TIMPs is likely to be independent of their activities as inhibitors of MMPs.

Trefoil peptides promote restitution of wounded corneal epithelial cells

The ocular surface shares many characteristics with mucosal surfaces. In both, healing is regulated by peptide growth factors, cytokines, and extracellular matrix proteins. However, these factors are not sufficient to ensure most rapid healing. Trefoil peptides are abundantly expressed epithelial cell products which exert protective effects and are key regulators of gastrointestinal epithelial restitution, the critical early phase of cell migration after mucosal injury. To assess the role of trefoil peptides in corneal epithelial wound healing, the effects of intestinal trefoil factor (ITF/TFF3) and spasmolytic polypeptide (SP/TFF2) on migration and proliferation of corneal epithelial cells were analyzed. Both ITF and SP enhanced restitution of primary rabbit corneal epithelial cells in vitro. While the restitution-enhancing effects of TGF-alpha and TGF-beta were both inhibited by neutralizing anti-TGF-beta-antibodies, trefoil peptide stimulation of restitution was not. Neither trefoil peptide significantly affected proliferation of primary corneal epithelial cells. ITF but not SP or pS2 mRNA was present in rabbit corneal and conjunctival tissues. In summary, the data indicate an unanticipated role of trefoil peptides in healing of ocular surface and demand rating their functional actions beyond the gastrointestinal tract.

Immunolocalization of matrix metalloproteinases and tissue inhibitors of metalloproteinases in human subconjunctival tissues

PURPOSE

To evaluate the roles of fibroblast proteins in the remodeling of the subconjunctival connective tissue, we immunohistochemically assessed the expression of matrix metalloproteinases (MMP)-1 and -2, and the tissue inhibitors of matrix metalloproteinases (TIMP)-1 and -2 in cultured human subconjunctival fibroblasts and in normal and healing human subconjunctival connective tissue.

METHODS

Cultured fibroblasts derived from human subconjunctival connective tissue and surgical specimens of normal and healing conjunctiva were immunostained with monoclonal antibodies directed against human MMPs and TIMPs and examined by light and electron microscopy.

RESULTS

In the cultured fibroblasts, MMP-1 and TIMP-1 antibodies stained the cytoplasm in a fine granular pattern, suggesting localization of those proteins in the endoplasmic reticulum (ER) and Golgi apparatus. Antibodies to MMP-2 and TIMP-2 reacted with fibroblast cytoplasm in a granular pattern. Electron microscopy of those fibroblasts revealed MMP-1 and TIMP-1 immunoreactivity in the ER cisternae or on the membrane of the ER. In surgical samples, MMP-1 and TIMP-1 were immunohistochemically detected in healing subconjunctival tissue, but not in conjunctival epithelium or normal subconjunctival tissue.

CONCLUSIONS

MMPs and TIMPs may be involved in remodeling of subconjunctival connective tissue and in fibroblast population after surgical interventions. These proteins may play a crucial role in the post-operative fibrotic process occurring during scar formation in subconjunctival tissue.