Coordinated elevation of membrane type 1-matrix metalloproteinase and matrix metalloproteinase-2 expression in rat uterus during postpartum involution

Upregulated TIMP1 facilitates and coordinates myometrial contraction by decreasing collagens and cell adhesive capacity during human labor

Myometrial contraction is one of the key events involved in parturition. Increasing evidence suggests the importance of the extracellular matrix (ECM) in this process, in addition to the functional role of myometrial smooth muscle cells, and our previous study identified an upregulated tissue inhibitor of metalloproteinase 1 (TIMP1) in human laboring myometrium compared to nonlabor samples. This study aimed to further explore the potential role of TIMP1 in myometrial contraction. First, we confirmed increased myometrial TIMP1 levels in labor and during labor with cervical dilation using transcriptomic and proteomic analyses, followed by real-time PCR, western blotting, and immunohistochemistry. Then, a cell contraction assay was performed to verify the decreased contractility after TIMP1 knockdown in vitro. To further understand the underlying mechanism, we used RNA-sequencing analysis to reveal the upregulated genes after TIMP1 knockdown; these genes were enriched in collagen fibril organization, cell adhesion, and ECM organization. Subsequently, a human matrix metalloproteinase (MMP) array and collagen staining were performed to determine the TIMPs, MMPs and collagens in laboring and nonlabor myometrium. A real-time cell adhesion assay was used to detect cell adhesive capacity. The results showed upregulated MMP8 and MMP9, downregulated collagens, and attenuated cell adhesive capacity in laboring myometrium, while lower MMP levels and higher collagen levels and cell adhesive capacity were observed in nonlabor. Moreover, TIMP1 knockdown led to restoration of cell adhesive capacity. Together, these results indicate that upregulated TIMP1 during labor facilitates and coordinates myometrial contraction by decreasing collagen and cell adhesive capacity, which may provide effective strategies for the regulation of myometrial contraction.

Increasing of matrix metalloproteinase 3 in bovine endometritis

Matrix metalloproteinase 3 (MMP3), a key member of the MMPs family, is involved in the modulation of endometrial inflammation and innate immunity. However, the role of MMP3 in bovine endometritis remains unknown. To investigate the role of MMP3 in bovine endometritis, endometrial MMP3 expression were determined in uterine biopsies from twenty 40-60 days postpartum dairy cows, which six were healthy cows and fourteen were endometritic cows. Moreover, MMP3 expression were also detected at different intensity of inflammatory response, which was induced by graded concentrations (0, 1, 5, 10 μg/ml) of LPS in bovine endometrial epithelial cells (BEECs) in vitro. RT-qPCR was used to test the mRNA levels of MMP3 in tissues or cells. Western blot was conducted to measure protein levels, and enzyme-linked immunosorbent assay (ELISA) was used for TNF-α and IL-1β in cell supernatant. Results showed that MMP3 mRNA and protein levels significantly increased and positive correlative with severity of endometritis in vivo. Likewise, MMP3 expression also positive correlative with intensity of LPS inflammatory response in BEECs in vitro. These results indicate that increasing of MMP3 directly correlates with bovine endometritis, and its increasing may contribute to progression of bovine endometritis.

Rumen-Protected Glucose Stimulates the Insulin-Like Growth Factor System and mTOR/AKT Pathway in the Endometrium of Early Postpartum Dairy Cows

This study aimed to elucidate the effects of a dietary rumen-protected glucose (RPG) addition on uterine involution through the analysis of an insulin-like growth factor (IGF) system and associated pathways in the post-natal endometrium. Twelve Holstein cows were assigned equally to two groups: a control group (CT) and an RPG group (200 g of RPG per cow per day). The plasma content of insulin-like growth factor 1 (IGF1) was determined by using the ELISA method. Expressions of IGF members, the matrix metalloproteinase, protein kinase B (AKT)/mechanistic target of rapamycin complex1 (mTOR) signaling pathway, and cell proliferation factors (proliferating cell nuclear antigen (PCNA) and Ki67) were detected using real-time polymerase chain reaction, Western blot, immunohistochemistry, and immunofluorescence, respectively. The results showed that the positive cells of PCNA and Ki67 were increased in the endometrium of RPG versus CT cows. The RPG addition significantly increased the plasma IGF1 level 14 d after delivery. The mRNA expressions of the IGF family members (IGF1, IGF2, type 1 IGF receptor (IGF1R) and IGF-binding proteins (IGFBP1, IGFBP2, IGFBP4 and IGFBP5)) were upregulated, and mRNA expressions of matrix metalloproteinase MMP3 and MMP9 were downregulated in cows from the RPG group compared with the CT group. Meanwhile, the protein expressions of IGF1, IGF2, IGF1R, IGFBP1 and IGFBP4 were upregulated in cows from the RPG group compared with the CT group. Immunohistochemical analysis identified a positive response for IGF1R and IGF2R in the endometrium of RPG versus CT cows. Furthermore, the RPG supplementation increased the protein expressions of phosphorylated (p)-AKT to total AKT and p-mTOR to total mTOR ratio in the endometrium. The current results indicated that the RPG supplementation promoted the proliferation of endometrial cells by stimulating the IGFs and mTOR/AKT pathway in the early post-natal endometrium of dairy cows.

Biological approaches for hypertrophic scars

Scar formation is usually the pathological consequence of skin trauma. And hypertrophic scars (HSs) frequently occur in people after being injured deeply. HSs are unusually considered as the result of tissue contraction and excessive extracellular matrix component deposition. Myofibroblasts, as the effector cells, mainly differentiated from fibroblasts, play the crucial role in the pathophysiology of HSs. A number of growth factors, inflammatory cytokines involved in the process of HS occurrence. Currently, with in-depth exploration and clinical research of HSs, various creative and effective treatments budded. In here, we summarize the progress in the molecular mechanism of HSs, and review the available biotherapeutic methods for their pathophysiological characteristics. Additionally, we further prospected that the comprehensive therapy may be more suitable for HS treatment.

Improvement in post-partum uterine involution in rats treated with Apios americana

OBJECTIVE

Apios americana, a plant used as a staple ingredient of native American diets, has various properties, including anti-cancer, anti-hyperglycemic, hypotensive, and anti-inflammatory activity. In Japan, Apios is used as a post-natal medication. After parturition, women undergo a period of recovery as they return to pre-pregnancy conditions. However, few health products that aid post-partum recovery are on the market. We explored whether Apios can accelerate the post-partum recovery process, in particular the involution of the uterus.

METHODS

Female rats kept in individual cages were mated with two male rats, with the exception of the control group (female rats without mating, on basal diet; n=6). After delivery, rats were divided into five groups based on their diet: basal diet (model; n=6); basal diet+oral intake at 5.4 g/kg of Chanfukang granules (a Chinese patent medicine preparation for post-partum lochia) (positive; n=6); basal diet containing 10% Apios powder (low; n=6); basal diet containing 20% Apios powder (medium; n=6); basal diet containing 40% Apios powder (high; n=6). Five days later, uteri and spleens were weighed. Uterus and spleen indices for each rat were calculated by dividing visceral weight by the total weight. Hormone and cytokine concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Histological analysis of uteri was completed using hematoxylin and eosin (H&E) staining. Expression of matrix metalloproteinases and inhibitors in uteri was measured by western blotting.

RESULTS

Our results showed that Apios treatment reduced the post-partum uterus index and regulated the hormone concentrations. Moreover, we found that the process of uterine involution was accelerated, based on morphological changes in the uterus. In addition, our results indicated that Apios alleviated the inflammatory response induced by the involution process. Transforming growth factor β was also found to be regulated by Apios. There were significant downregulation of matrix metalloproteinases and upregulation of their inhibitors by Apios, which suggested that Apios increased the rate of the collagen clearance process.

CONCLUSIONS

These results, based on experimental observations at the molecular and protein levels, verified our hypothesis that Apios can improve uterine involution, and demonstrated the potential application of Apios in post-partum care.

Malnutrition with hypoaminoacidemia in a 22-year-old pregnant patient masking a likely ornithine transcarbamylase deficiency

BACKGROUND

Symptoms and clinical presentations of OTC deficiency vary widely according to the remaining activity of the enzyme. Three factors determine the residual enzyme activity. First, as the OTC gene is carried on the X chromosome, a complete inactivation of this enzyme in a newborn boy results an acute ammonia intoxication. Second, the female mosaicism due to lyonization (differential randomized X-inactivation) leads to differential OTC expression in hepatocytes. Third, the degree of severity depends on the mutation and the level of remaining activity it leaves to the protein. Published cases of OTC deficiency during pregnancy are scant. Most often, diagnosis of the metabolic disease is made before pregnancy or during the post-partum period.

METHODS

We report the case of a 22-year-old woman's successful pregnancy with a moderate form of ornithine transcarbamylase (OTC) deficiency, unsuspected before pregnancy, biochemically consistent with plasma aminoacidogram and orotic acid analysis, and initially masked by malnutrition.

RESULTS - CONCLUSION

Although maternal ammonia was subnormal and the neonate was safe, an OTC deficiency was revealed by stress factors such as the pregnancy itself and infection, and associated with uncontrollable maternal vomiting and psychiatric syndrome. However, this metabolic disease, revealed by aminoacidogram and urine orotic acid analysis, fortunately did not prevent a successful pregnancy. Even if infrequent, this situation deserves to be highlighted.

The increased of MMP-9 and MMP-2 with the decreased of TIMP-1 on the uterosacral ligament after childbirth

Introduction

Pelvic floor dysfunction is one of the causes of morbidity that have very active role in the degradation of collagen and elastin through an intermediary changes in matrix metalloproteinases (MMP) and its regulation. This research to evaluate level of MMP-9, MMP-2 and TIMP-1 expression on uterosacral ligament in women after vaginal delivery.

Methods

This research was conducted by collecting samples in consecutive sampling of biopsy uterosacral ligament from primigravida who underwent cesarean section because of obstructive labor at stage 1 and 2. As control, biopsy samples were taken from uterosacral ligament of primigravida a term who have not entered the labor phase and undergoing elective caesarean section surgery. The method in this study was cross sectional. The examination of MMP-9, MMP-2, and TIMP-1 expression by immunohistochemistry based on comparison of the sample and the control differences.

Results

There are differences in the levels of Matrix Metalloproteinase-9, Matrix Metalloproteinase-2, and TIMP-1 in the uterosacral ligament of primigravida women in labor compared with women who are never in labor.

Conclusion

There are increased levels of Matrix Metalloproteinase-9 and Matrix Metalloproteinase-2 with the decreased of TIMP-1 in the uterosacral ligament of primigravida women who underwent cesarean section because of obstructive labor at stage 1 and 2.

Urinary phthalate metabolite concentrations in relation to levels of circulating matrix metalloproteinases in pregnant women

Phthalate exposure has been shown to be associated with adverse pregnancy outcomes. However, human studies informing relevant mechanistic pathways are lacking. Experimental studies have reported that matrix metalloproteinases (MMPs), which are responsible for extracellular protein degradation, may be upregulated in response to phthalate exposure. In this exploratory study we measured urinary phthalate metabolite concentrations, plasma MMP levels, and relevant covariates among 134 pregnant women. There were statistically significant or suggestive positive relationships between several phthalates, particularly between metabolites of di-(2-ethylhexyl) phthalate, with MMP-1 and MMP-9 levels. Further research is needed to confirm these results and how they may inform the mechanisms involved between phthalate exposure and adverse pregnancy outcomes.

Expression of Matrix Metalloproteinases in the Mouse Uterus and Human Myometrium During Pregnancy, Labor, and Preterm Labor

BACKGROUND

Uterine extracellular matrix (ECM) remodeling occurs throughout pregnancy and at parturition. Imbalanced availability of key mediators in ECM degradation, namely, matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), is implicated in the pathogenesis of preterm labor (PTL).

OBJECTIVES

Examine the expression of MMPs and their inhibitors TIMPs in (a) the mouse uterus throughout normal gestation, at labor, and during inflammation-induced PTL and (b) the human term and preterm myometrium.

METHODS

The expression of Mmp-2/9/3/10 and Timp-1/2 was determined in the uterus of C57BL/6 mice (n = 6/group) during pregnancy (on days (d) 5, 8, 12, 15, 17, and 18), at normal labor, and during lipopolysaccharide-induced PTL (n = 6/group). The expression of MMP-10 and TIMP-1 was determined in human term and preterm myometrium before the onset of labor (TNL, n = 7; PTNL, n = 7) and during active labor (TL, n = 8; PTL, n = 8). Gene expression and tissue localization were assessed by quantitative polymerase chain reaction and immunohistochemistry, respectively.

RESULTS

Mmp-10 was higher during murine labor (53-fold vs early pregnancy) in contrast to Mmp-2/3/9 and Timp-1, the expression of which reached a nadir at labor ( P < .001 vs d5 [ Mmp-2/ 9] or P < .05 vs d8 [ Mmp-3 and Timp-1]). The Mmp-3/10 and Timp-1 were localized to the uterine epithelium and stroma/myometrium. In the human myometrium, TIMP-1 messenger RNA was higher and MMP-10 was lower in TL versus TNL ( P < .05), PTL ( P < .001), and PTNL ( P < .001). MMP-10 and TIMP-1 were localized to the myometrial smooth muscle cells, interstitial fibroblasts, and inflammatory cells.

CONCLUSIONS

These data implicate MMP-3, TIMP-1, and MMP-10 in the uterine ECM remodeling during physiological and pathological parturition.

BLID: A Novel Tumor-Suppressor Gene

BLID (BH3-like motif containing, cell death inducer), also known as breast cancer cell 2 (BRCC2), was first reported in the human breast cancer cell line in 2004. BLID is a BH3-like motif containing apoptotic member of the Bcl-2 family. Recently, the BLID tumor-suppressor roles have been fully established. Several studies have found that BLID is frequently downregulated in many human cancers and the downregulation is often associated with tumor progression. Multivariate analysis indicated that BLID is an independent prognostic factor for overall survival and distant metastasis-free survival. Moreover, BLID can inhibit breast cancer cell growth and metastasis and promote apoptosis. BLID can regulate the expression of various tumor-related genes and proteins, such as AKT and MMP. In this review, we provide an overview of current knowledge concerning the role of BLID in tumor development and progression. To our knowledge, this is the first review about the role of this novel tumor-suppressor gene in tumor development and progression.

Roles and regulation of the matrix metalloproteinase system in parturition

Significant tissue destruction, repair, and remodeling are involved in parturition, which involves fetal membrane rupture, cervical ripening, and uterine contraction and its subsequent involution. Extracellular matrix degradation and remodeling by proteolytic enzymes, such as matrix metalloproteinases (MMPs), are required for the final steps of parturition. MMPs participate in physiological degradation and remodeling through their proteolytic activities on specific substrates, and are balanced by the action of their inhibitors. Disruption to this balance can result in pathological stress that ends with preterm or post-term birth or pre-eclampsia. In this review, we examine the roles and regulation of the MMP system in physiological and pathological labor, and propose a model that illustrates the mechanisms by which the MMP system contributes to these processes.

Forkhead box O1 (FOXO1) in pregnant human myometrial cells: a role as a pro-inflammatory mediator in human parturition

Prematurity is the most important complication contributing to neonatal morbidity and mortality. It is the untimely activation of the terminal events of human parturition that lead to preterm birth, with inflammation playing a driving role in initiating uterine contractions. The purpose of this study was to investigate the role of Forkhead box O1 (FOXO1), a pro-inflammatory modulator, during human parturition. FOXO1 mRNA expression was quantified using qRT-PCR, and protein expression using Western blotting in myometrial biopsies from pregnant non-labouring and labouring women at term. In addition, the effect of FOXO1 knockdown in human myometrial cells on IL-β-stimulated expression of pro-inflammatory mediators was investigated. Levels of FOXO1, at both the gene and protein levels, were higher in myometrium obtained from women in labour compared with samples taken from non-labouring women. FOXO1 deletion in myometrial cells attenuated the capacity of IL-1β to induce inflammatory gene expression. Specifically, FOXO1 knockdown significantly decreased IL-1β-induced IL-6 and IL-8 expression; production and COX-2 expression and subsequent prostaglandin (PGE2 and PGF2α) release; and MMP-9 mRNA expression and activity. In summary, this study demonstrates for the first time the potential role of FOXO1 inflammatory events of both physiological and pathological labour in human myometrium, and may provide a therapeutic target in the management of preterm labour.

Curative effects of oleanolic Acid on formed hypertrophic scars in the rabbit ear model

Hypertrophic scarring is a common proliferative disorder of dermal fibroblasts characterized by collagen overproduction and excessive deposition of extracellular matrix (ECM). There is no consensus about the best therapeutics to produce complete and permanent improvement of scars with few side effects. To investigate the therapeutic effects of oleanolic acid (OA) on hypertrophic scars and explore the possible mechanism of action involved, a rabbit ear model with hypertrophic scars was established. OA (2.5%, 5%, and 10%) was given once daily to the scars for 28 consecutive days. As a result, OA significantly alleviated formed hypertrophic scars on rabbit ears. The levels of TGF-β₁, MMP-1, TIMP-1, and collagens I and III were notably decreased, and the number of apoptosis cells and mRNA expression of MMP-2, caspase-3, and caspase-9 were markedly increased in the scar tissue. The scar elevation index (SEI) was also evidently reduced. Histological findings exhibited significant amelioration of the collagen tissue. These results suggest that OA has the favorable curative effects on formed hypertrophic scars in the rabbit ear model, and the possible mechanism of action is that OA decreases HSFs proliferation and increases HSFs apoptosis by reduction of P311 gene expression and TGF-β₁ production, inhibition of TIMP-1 secretion, enhancement of MMP-2 activity, and subsequently facilitation of degradation of collagen types I and III.

Immunohistochemical localization of beta defensins in the endometrium of rat uterus during the postpartum involution period

β-Defensins are small cationic molecules that have antimicrobial actions against bacteria, fungi and viruses and contribute to mucosal immune responses at epithelial sites. The female reproductive tract is an important site of defensin production. This study was conducted to determine the possible changes in proportions and localization of β-defensin 1-4 in the rat uterus at the 1st, 3th, 5th, 10th and 15th days of postpartum and at the period of diestrus using immunohistochemical techniques. In the present study, it was determined that β-defensin 1-4 were generally found in all structural components of the endometrium (luminal and glandular epithelium, stromal cells and blood vessels) in both the nucleus and the cytoplasm of cells during the involution period and diestrus. Suprisingly, immunoreaction of β-defensin 2 was also observed in the lateral membrane of the luminal and glandular epithelial cells on the 10th day of involution and immunostaining of β-defensin 4 was also localized in the apical membrane of the luminal and glandular epithelial cells. The current study demonstrated β-defensin 1-4 immunoreactivities in the endothelium of blood vessels were stronger throughout the involution period. Although β-defensins 2 and 3 were localized in both the nuclei and the cytoplasm of endothelial cells, β-defensins 1 and 4 were present in only cytoplasm. These results show that the most component of rat endometrium expresses human β-defensin 1-4 in a involution-dependent manner. Therefore it may be asserted that these molecules constitute a organised protection to prevent uterus from probable infections during the involution process.

Influence of energy balance on the somatotrophic axis and matrix metalloproteinase expression in the endometrium of the postpartum dairy cow

Postpartum dairy cows enter a period of negative energy balance (NEB) associated with low circulating IGF1, during which the uterus must undergo extensive repair following calving. This study investigated the effects of NEB on expression of IGF family members and related genes in the involuting uterus. Cows were allocated to two treatments using differential feeding and milking regimes to produce mild NEB or severe NEB (SNEB). Uterine endometrial samples collected 2 weeks post partum were analysed by quantitative PCR. The expression of IGF-binding protein 4 (IGFBP4) mRNA increased in the endometrium of SNEB cows, with trends towards increased IGFBP1 and reduced IGFBP6 expression. There were no significant differences between treatments in mRNA expression of IGF1, IGF2 or of any hormone receptor studied, but significant correlations across all cows in the expression levels of groups of receptors suggested common regulatory mechanisms: type 1 IGF receptor (IGF1R), IGF2R and insulin receptor (INSR); GHR with ESR1; and ESR2 with NR3C1. The expression of IGF1R and INSR also positively correlated with the circulating urea concentration. Matrix metalloproteinases (MMPs) are important in tissue remodelling and can affect IGF signalling via interaction with IGFBPs. The expression levels of MMP1, MMP3, MMP9 and MMP13 mRNAs all showed major upregulation in the endometrium of cows in SNEB and all except MMP9 were highly correlated with expression of IGFBP4. Alpha(2)-HS-glycoprotein (AHSG) and PDK4, two genes implicated in insulin resistance, were also highly expressed in SNEB. These results suggest that cows in SNEB experience alterations to the IGF and insulin signalling pathways in the postpartum endometrium. This may affect the rate of tissue repair with a possible negative impact on subsequent fertility.

The effect of maternal malnutrition during lactation on the endometrial ERalpha expression, collagen type, and blood vessels in the rats offspring at puberty

The aim of this manuscript was to evaluate the effects of maternal protein-energy-restriction and energy restriction during lactation on endometrial collagen and blood vessels, uterus Eralpha expression, and estradiol serum levels in the rats offspring at puberty. At parturition, dams were grouped as: control group (C), with free access to standard rat chow containing 23% protein and 17,038.7 KJ/Kg; protein-energy restricted group (PER), with free access to formulated chow containing 8% protein but made isoenergetic to the C diet (17,038.7 KJ/Kg); and energy-restricted group (ER), which received standard rat chow containing 23% protein based on the mean ingestion of the PER group corresponding to 60% of that consumed by the control group. After weaning, all female pups had free access to standard laboratory chow until puberty, when they were killed at the diestrum stage. The uterine ERalpha expression was determined by Western-Blot and estradiol serum levels by radioimmunoassay. Endometrial collagen and blood vessels were quantified by stereology. The volumetric density of blood vessels (C = 70.7 +/- 2.2; PER = 29.2 +/- 2.4; ER = 32.3 +/- 3.6; P < 0.001) and endometrial collagen (C = 31.1 +/- 1; PER = 26.9 +/- 1.0; ER = 26.5 +/- 0.7; P < 0.05) were significantly reduced in both malnourished groups. The ER group presented higher estradiol serum levels (C = 69.2 +/- 6.4; PER = 73.4 +/- 5.5; ER = 101.0 +/- 5.4; P < 0.01) in relation to C and PER groups. ERalpha expression was greater in both malnourished groups (C = 0.11 +/- 0.02; PER = 0.41 +/- 0.12; ER = 0.35 +/- 0.03; P < 0.05). In conclusion, maternal malnutrition during lactation caused changes in endometrial angiogenesis, collagen deposition, and Eralpha expression in female offspring that will appear in puberty and could affect the reproductive biology of the female offspring.

SAR150640, a selective beta3-adrenoceptor agonist, prevents human myometrial remodelling and activation of matrix metalloproteinase in an in vitro model of chorioamnionitis

BACKGROUND AND PURPOSE

The uterine pathophysiology underlying inflammatory conditions such as chorioamnionitis remains largely unclear. As we have shown that beta(3)-adrenoceptors act as regulators of myometrial inflammation, we wanted to investigate the potential role of beta(3)-adrenoceptors in preventing uterine remodelling induced by inflammation.

EXPERIMENTAL APPROACH

The consequences of human chorioamnionitis on myometrial remodelling were characterized by Sirius Red staining and metalloproteinase (MMP) expression, and compared with the effects of incubating human myometrial samples with Escherichia coli lipopolysaccharide (LPS) in vitro. We also assessed the effect of SAR150640, a selective beta(3)-adrenoceptor agonist, on the production and activity of MMPs.

KEY RESULTS

Chorioamnionitis was associated with a 46% decrease in total collagen, as well as over-expression of MMP2 (+61%) and MMP9 (+84%); both effects were reproduced by incubation with LPS (10 microg x mL(-1), 48 h). LPS-induced over-expression of MMP2 and MMP9 in normal human myometrium was paralleled by an overactivity of the proteins. Both over-expression and overactivity were prevented by the beta(3)-adrenoceptor agonist SAR150640 in a concentration-dependent manner. SAR150640, by itself, did not exhibit any effect on MMP production in control tissues.

CONCLUSIONS AND IMPLICATIONS

This study shows that inflammation was associated with an intense remodelling of human myometrium, a process likely to be explained by MMP activation. Our study emphasizes the potential therapeutic relevance of beta(3)-adrenoceptor agonists to the treatment of preterm labour and other uterine inflammatory conditions.

Differential activity of matrix metalloproteinases (MMPs) during photoperiod induced uterine regression and recrudescence in Siberian hamsters (Phodopus sungorus)

Siberian hamsters adapt to seasonal changes by reducing their reproductive function during short days (SD). SD exposure reduces uterine mass and reproductive capacity, but underlying cellular mechanisms remain unknown. Because matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are important in uterine development, parturition, and postpartum remodeling, their expression in uterine tissue from Siberian hamsters undergoing photoperiod-mediated reproductive regression and recrudescence was investigated. Female hamsters were exposed to long day (LD, 16L:8D, controls) or SD (8L:16D) for 3-12 weeks (regression); a second group was exposed to SD or LD for 14 weeks and then transferred to LD for 0-8 weeks (recrudescence). Hamsters were euthanized, uteri collected, and homogenates analyzed by gelatin zymography or Western blotting for MMP and TIMP protein levels. Uterine weight decreased (67-75%) at SD weeks 12-14 and increased post-LD transfer (PT) reaching LD values by PT week 2. MMP-2, but not MMP-9 activity was reduced by SD week 12 or 14 but increased to LD levels at PT week 2. MMP-3 expression increased at SD week 9 compared to other SD and LD groups. MMP-14 and -13 protein levels decreased at SD week 3 but returned to LD levels by SD week 6. During recrudescence, MMP-3 (PT weeks 0-2), MMP-13 (PT week 4), and MMP-14 (PT weeks 2, 4) protein levels were higher than LD. TIMP-1 and 2 were present at low levels. Significant and differential variations in uterine MMP activity/expression during photoperiod-induced regression and recrudescence were observed. These changes likely reflect increases in tissue remodeling during both the adaptation to SD and the restoration of reproductive function.

Hormones restore biomechanical properties of the vagina and supportive tissues after surgical menopause in young rats

OBJECTIVE

The objective of the study was to determine the impact of hormones on the biomechanical properties of the vagina and its supportive tissues following surgical menopause in young vs middle-aged rats.

STUDY DESIGN

Long-Evans rats (4-month virgin [n = 34], 4-month parous [n = 36], and 9-month parous [n = 34]), underwent ovariectomy (OVX) or sham surgery. OVX animals received hormones (estrogen [E2] or estrogen plus progesterone [E2 plus P4]), placebo, or a matrix metalloproteinase inhibitor (chemically modified tetracycline-8 [CMT-8]). Animals were euthanized after 8 weeks and the biomechanical properties of the vagina and supportive tissues determined. Data were analyzed using a 1-way analysis of variance and posthoc tests.

RESULTS

OVX induced a rapid decline in the biomechanical properties of pelvic tissues in young but not middle-aged rats. Supplementation with E2, E2 plus P4, or CMT-8 restored tissues of young rats to control levels with no effect on middle-aged tissues. Parity did not have an impact on tissue behavior.

CONCLUSION

OVX has a differential effect on the tissues of young vs middle-aged rats.

Significance of matrix metalloproteinases in the pathophysiology of the ovary and uterus

Matrix metalloproteinases (MMP) are capable of degrading a variety of extracellular matrix (ECM) proteins and are also involved in the processing of a number of bioactive molecules. Our findings indicate that the functions of MMP in the ovary and uterus are organ-specific and time-dependently vary during the reproductive cycle. Prolactin induces structural luteolysis indicated by loss of luteal weight, protein and DNA within 36 h after pretreatment with ergot alkaloid. MMP activation appears crucial for the selective depletion of protein during luteal involution, which entails loss of ECM accompanied by apoptosis. During GnRHagonist-induced luteolysis, this response was also associated with marked increases in MMP-2, which degraded collagen type IV, and MT1-MMP, which in addition to activating MMP-2 also degrades collagen type I, III and V. We also found that the level of MT1-MMP and MMP-2 expression in the human CL is greater during the late luteal phase than during either the early mid luteal phases or during gestation, respectively. That dehydroepiandrosterone (DHEA) treatment caused the formation of cysts from antral follicles in the ovaries of immature rats while depressing MMP-2 collagenolytic activity and enhancing lysyl oxidase expression highlights the importance of collagen degradation in the process of ovulation and suggests that changes in the activities of these enzymes play a key role in ovarian cystogenesis in polycystic ovary syndrome patients. Furthermore, immunohistochemical analyses showed that MT1-MMP and FasL co-localize with TdT-mediated dUTP-biotin nick end-labeling (TUNEL)-positive apoptotic granulosa cells in rats treated with DHEA, that the Fas/FasL/Caspase-8 (death receptor-dependent) pathway is pivotal for follicular atresia and that increased levels of MT1-MMP likely play an important role in tissue remodeling during follicular atresia. After parturition, the uterus undergoes involution, a conspicuous feature characterized by a rapid reduction in the collagen content mediated by degradation of extracellular collagen bundles. Our findings strongly suggest that MT1-MMP, MMP-2 and MMP-9 are each time-dependently regulated and play important roles in tissue remodeling during postpartum uterine involution. (Reprod Med Biol 2006; 5: 235-243).