Interleukin-1alpha treatment of meniscal explants stimulates the production and release of aggrecanase-generated, GAG-substituted aggrecan products and also the release of pre-formed, aggrecanase-generated G1 and m-calpain-generated G1-G2

Pro-inflammatory cytokines induce meniscal matrix degradation and inhibition of endogenous repair mechanisms, but the pathogenic mechanisms behind this are mostly unknown. Therefore, we investigated details of interleukin-1 (IL-1alpha)-induced aggrecan turnover in mature meniscal tissue explants. Fibro-cartilagenous disks (3 mm diameter x 1 mm thickness) were isolated from the central, weight-bearing region of menisci from 2-year-old cattle. After 3 or 6 days of IL-1alpha-treatment, GAG loss (DMMB assay), biosynthetic activity ([(35)SO(4)]-sulfate and [(3)H]-proline incorporation), gene expression (quantitative RT-PCR) and the abundance (zymography, Western blot) of matrix-degrading enzymes and specific aggrecan products were determined. Meniscal fibrocartilage had a 4-fold lower GAG content (per wet weight) than adjacent articular cartilage, and expressed MMPs-1, -2, -3 and ADAMTS4 constitutively, whereas ADAMTS5 m-RNA was essentially undetectable. Significant IL-1 effects were a decrease in biosynthetic activity, an increase in GAG release and in the expression/abundance of MMP-2, MMP-3 and ADAMTS4. Fresh tissue contained aggrecan core protein products similar to those previously described for bovine articular cartilage of this age. IL-1 induced the release of aggrecanase-generated CS-substituted products including both high (>250 kDa) and low molecular weight (about 75 kDa) species. TIMP-3 (but not TIMP-1 and -2 or a broad spectrum MMP inhibitor) inhibited IL-1-dependent GAG loss. In addition, IL-1 induced the release of preformed pools of three known G1-bearing products. We conclude that aggrecanases are responsible for IL-1-stimulated GAG release from meniscal explants, and that IL-1 also stimulates release of G1-bearing products, by a process possibly involving hyaluronan fragmentation.

Rofecoxib regulates the expression of genes related to the matrix metalloproteinase pathway in humans: implication for the adverse effects of cyclooxygenase-2 inhibitors

BACKGROUND

Cyclooxygenase-2 (COX-2) and COX-2-derived prostaglandins contribute to acute inflammation and pain, as well as resolution of inflammation; inhibition of COX-2 results in persistence of inflammation. Because matrix metalloproteinases (MMPs) play an essential role in inflammatory tissue injury and their activity is regulated by COX-2-derived prostaglandin E2, we evaluated whether COX-2 inhibition is associated with MMP overexpression during acute inflammation.

METHODS

A total of 102 oral mucosal biopsy specimens were taken from 51 healthy volunteers who required extraction of impacted third molars. Subjects randomly received either rofecoxib (50 mg daily), ibuprofen (400 mg 4 times per day), or placebo 90 minutes before surgery and up to 48 hours after surgery. Total ribonucleic acid extracted from each biopsy specimen was used to analyze changes in gene expression related to the MMP pathway after tissue injury and drug treatments by use of microarray and quantitative real-time polymerase chain reaction in this clinical model of acute inflammation.

RESULTS

Following tissue injury, rofecoxib increased the expression of genes associated with degradation of the extracellular matrix, including MMP-1 (64.7 +/- 6.5, P = .010), MMP-3 (41.7 +/- 4.8, P = .007), PLAT (encoding tissue plasminogen activator) (10.9 +/- 4.6, P = .032), and IL8 (encoding interleukin 8) (8.3 +/- 6.7, P = .020), and decreased the expression of TIMP3 (encoding tissue inhibitor of metalloproteinase 3) (6.2 +/- 2.8, P = .027). Ibuprofen produced similar effects on the expression of MMP-1 (23.4 +/- 5.0, P = .016) and MMP-3 (26.3 +/- 4.2, P = .003). In contrast, the expression of these genes was not statistically changed after tissue injury in the placebo group. The microarray data were in concordance with the changes in gene expression confirmed by quantitative real-time polymerase chain reaction.

CONCLUSION

These findings provide evidence at the transcriptional level that inhibition of COX-2, in the presence of acute inflammation, induces changes in gene expression related to the MMP pathway. These changes may contribute to the adverse effects attributed to COX-2 inhibition by interfering with resolution of inflammation.

Effect of matrigel on human extravillous trophoblasts differentiation: modulation of protease pattern gene expression

The human placenta is characterized by extensive trophoblast invasion of the uterus. Indeed, extravillous cytotrophoblast cells invade the decidua and the upper third of uterine spiral arteries in the myometrium. This invasion is reflected in situ by the expression of specific markers. In order to study this invasion process, we have established an in vitro culture model of human extravillous trophoblast isolated from first trimester chorionic villi. The aim of this study was to investigate the effect of a composite matrix, the Matrigel required for the culture of this homogenous population of extravillous trophoblasts (EVCT), on their in vitro differentiation. The effect of Matrigel was studied on different markers characterized by immunocytochemistry and by real-time polymerase chain reaction assay of transcripts. In addition, the expression of 12 different matrix metalloproteases and their inhibitors were investigated. We show that human extravillous cytotrophoblasts acquire an invasive phenotype on Matrigel associated with a specific pattern of protease gene expression. This in vitro model will be of interest to study the cellular mechanisms involved in abnormal trophoblast invasion observed in poor placentation and preeclampsia.

Relaxin enhances in-vitro invasiveness of breast cancer cell lines by up-regulation of matrix metalloproteases

Until recently, relaxin (RLX) has been known predominantly for its effects on the reproductive system, where it induces remodelling of the extracellular matrix and up-regulation of matrix metalloproteases (MMPs). In solid cancers, tissue remodelling and MMP activation are essential for invasion and metastasis. We therefore investigated the effect of RLX on invasiveness and MMP expression of human breast cancer cell lines. Upon incubation with porcine RLX, the invasiveness of SK-BR3 cells was significantly increased. Similar effects could be achieved in MCF-7 cells, especially when RLX was combined with epidermal growth factor. Enhanced invasiveness was accompanied by up-regulation of MMP production and could be almost completely blocked by the MMP inhibitor FN 439. Zymography revealed increased secretion of MMP-2, -7 and -9, associated with up-regulated mRNA concentrations of MMP-2, -9, -13 and -14. mRNA expression levels of MMP-1, -3, -7, -8, -10, -11, -12 and of tissue inhibitors of metalloproteases-1, -2, -3 and -4 were either very low or not detectably influenced by RLX. Taken together, RLX enhances in-vitro invasiveness of breast cancer cell lines by induction of MMP expression. It remains to be clarified whether RLX might play a similar role in vivo and promote tumour progression.

Matrix metalloproteases and their inhibitors are produced by overlapping populations of activated astrocytes

Matrix metalloproteases (MMPs) and tissue inhibitors of metalloproteases (TIMPs) are involved in many cell migration phenomena and produced by many cell types, including neurons and glia. To assess their possible roles in brain injury and regeneration, we investigate their production by glial cells, after brain injury and in tissue culture, and we investigate whether they are capable of digesting known axon-inhibitory proteoglycans. To determine the action of MMPs, we incubated astrocyte conditioned medium with activated MMPs, then did western blots for several chondroitin sulphate proteoglycans. MMP-3 digested all five proteoglycans tested, whereas MMP-2 digested only two and MMP-9 none. To determine whether MMPs or TIMPs are produced by astrocytes in vitro, we tested both primary cultures and astrocyte cell lines by western blotting, and compared them with Schwann cells. All cultures produced at least some MMPs and TIMPs, with no obvious correlation with the ability of axons to grow on those cells. Both MMP-9 and TIMP-3 were regulated by various cytokines. To determine which cells produce MMPs and TIMPs after brain injury, we made lesions of adult rat cortex, and did immunohistochemistry. MMP-2 was seen to be induced in activated astrocytes through the whole thickness of the cortex but not deeper, but MMP-3 was not seen in the injured brain. TIMP-2 and TIMP-3 immunoreactivities were induced in activated astrocytes in deep cortex and the underlying white matter. In situ hybridisation confirmed induction of TIMP-2 in glia as well as neurons, but showed no expression of TIMP-4. These results show that both MMPs and TIMPs are produced by some astrocytes, but TIMP production is particularly strong, especially in deep cortex and white matter which is more inhibitory for axon regeneration. Conversely the MMPs produced may not be adequate to promote migration of cells and axons within the glial scar.

Fibrogenic and inflammatory cytokines modulate mRNA expressions of matrix metalloproteinase-3 and tissue inhibitor of metalloproteinase-3 in type II pneumocytes

BACKGROUND

Imbalance between proteinases and their inhibitors released from alveolar type II pneumocytes may cause development of inflammatory lung diseases.

OBJECTIVES AND METHODS

We examined mRNA expressions of matrix metalloproteinase-3 (MMP-3) and tissue inhibitor of metalloproteinase-3 (TIMP-3) in a cell line (A549) and in primary culture of normal adult human type II pneumocytes using reverse transcription-competitive polymerase chain reaction.

RESULTS

Interleukin-1beta (IL-1beta) and transforming growth factor-beta1 (TGF-beta1) increased MMP-3 and TIMP-3 expressions in A549 cells in a time- and concentration-dependent manner. IL-1beta mainly augmented MMP-3 expression, while TGF-beta1 mainly augmented TIMP-3 expression. Dexamethasone attenuated both IL-1beta- and TGF-beta1-stimulated expressions of MMP-3 and TIMP-3. Interleukin-10 had no significant effect. Hepatocyte growth factor alone had no effect on constitutive MMP-3 expression or TIMP-3 expression, but it augmented TGF-beta1-stimulated MMP-3 expression. The constitutive expressions were higher in normal type II pneumocytes than in A549 cells, but the regulations were similar.

CONCLUSIONS

These data indicated that the matrix degradation is enhanced by IL-1beta and suppressed by TGF-beta1 via regulations in the balance between MMP-3 and TIMP-3. Further, these regulations were shown to be modulated by glucocorticoids and growth factors.

Tissue inhibitor of metalloproteinases (TIMP)-1, -2 and -3 in human endometrium during the menstrual cycle

The extensive remodelling of the human endometrium throughout the menstrual cycle is accompanied by changes in production of matrix metalloproteinases, the activity of which can be inhibited by specific tissue inhibitors or by tissue inhibitors of metalloproteinases (TIMP)s with a 1:1 stoichiometry. This study immunolocalized TIMP-1, TIMP-2 and TIMP-3 in dated normal human endometrium across the menstrual cycle and examined cultured endometrial cells for their production. All three TIMPs were present in the major cellular compartments, luminal epithelium, glands, stroma, endothelial cells and vascular smooth muscle cells with the most intense immunoreactivity in the luminal epithelium. TIMP-1 and -3 were lower in the mid-to-late proliferative phase with a nadir of TIMP-3 particularly in the late proliferative phase. Decidualized stromal cells stained strongly positive for TIMP-1, -2 and -3. Cells of haematopoietic origin never stained. Monensin treatment of tissue resulted in accumulation of TIMPs in all cellular compartments but particularly of TIMP-1 in epithelium. Cultured endometrial stromal cells released more TIMP-1 than TIMP-2 or TIMP-3 into culture medium and all were increased following decidualization in vitro. Epithelial cells in culture produced less TIMPs than stromal cells, and only a few epithelial cells in each culture were immunopositive for TIMP-1. The ubiquitous distribution of TIMPs implicates them in maintenance of endometrial integrity, with changes in the matrix metalloproteinases without concomitant changes in TIMPs determining endometrial matrix degradation.