CCN3 (NOV) Drives Degradative Changes in Aging Articular Cartilage.

Aging is a major risk factor of osteoarthritis, which is characterized by the degeneration of articular cartilage. CCN3, a member of the CCN family, is expressed in cartilage and has various physiological functions during chondrocyte development, differentiation, and regeneration. Here, we examine the role of CCN3 in cartilage maintenance. During aging, the expression of Ccn3 mRNA in mouse primary chondrocytes from knee cartilage increased and showed a positive correlation with p21 and p53 mRNA. Increased accumulation of CCN3 protein was confirmed. To analyze the effects of CCN3 in vitro, either primary cultured human articular chondrocytes or rat chondrosarcoma cell line (RCS) were used. Artificial senescence induced by H2O2 caused a dose-dependent increase in Ccn3 gene and CCN3 protein expression, along with enhanced expression of p21 and p53 mRNA and proteins, as well as SA-ß gal activity. Overexpression of CCN3 also enhanced p21 promoter activity via p53. Accordingly, the addition of recombinant CCN3 protein to the culture increased the expression of p21 and p53 mRNAs. We have produced cartilage-specific CCN3-overexpressing transgenic mice, and found degradative changes in knee joints within two months. Inflammatory gene expression was found even in the rib chondrocytes of three-month-old transgenic mice. Similar results were observed in human knee articular chondrocytes from patients at both mRNA and protein levels. These results indicate that CCN3 is a new senescence marker of chondrocytes, and the overexpression of CCN3 in cartilage may in part promote chondrocyte senescence, leading to the degeneration of articular cartilage through the induction of p53 and p21.

Bone marrow-derived cells contribute to pulmonary vascular remodeling in hypoxia-induced pulmonary hypertension.

STUDY OBJECTIVE: In these days, it was reported that bone marrow (BM) cells might take part in the remodeling of some systemic vascular diseases; however, it remains unknown whether the BM cells were involved in the vascular remodeling of pulmonary arteries and the progression of pulmonary hypertension (PH). The purpose of this study was to investigate whether BM-derived cells contribute to pulmonary vascular remodeling in hypoxia-induced PH. MATERIALS AND METHODS: To investigate the role of BM-derived cells, we transplanted the whole BM of enhanced green fluorescent protein (GFP)-transgenic mice to the lethally irradiated syngeneic mice (n = 30). After 8 weeks, chimera mice were exposed to consistent hypoxia using a hypoxic chamber (10% O(2)) for up to 4 or 8 weeks (10 mice per group). After hemodynamics and the ratio of right ventricular (RV) weight to left ventricle (LV) weight, RV/(LV + septum [S]), were measured, histologic and immunofluorescent staining were performed. RESULTS: BM-transplanted mice showed a high chimerism (mean [+/- SEM], 91 +/- 2.3%). RV systolic pressure and the RV/(LV + S) ratio increased significantly with time in PH mice, indicating RV hypertrophy. Marked vascular remodeling including medial hypertrophy and adventitial proliferation was observed in the pulmonary arteries of PH mice. Strikingly, a number of GFP(+) cells were observed at the pulmonary arterial wall, including the adventitia, in hypoxia-induced PH mice, while very few cells were observed in the control mice. Metaspectrometer measurements using confocal laser scanning microscopy confirmed that this green fluorescence was produced by GFP, suggesting that these GFP(+) cells were mobilized from the BM. Most of them expressed alpha-smooth muscle actin, a smooth muscle cell, or myofibroblast phenotype, and contributed to the pulmonary vascular remodeling. A semiquantitative polymerase chain reaction of the GFP gene revealed that the BM-derived GFP-positive cells in the PH group were observed more than eightfold as often compared with the control mice. CONCLUSION: The BM-derived cells mobilize to the hypertensive pulmonary arteries and contribute to the pulmonary vascular remodeling in hypoxia-induced PH mice.

Norepinephrine-induced nerve growth factor depletion causes cardiac sympathetic denervation in severe heart failure.

In severe congestive heart failure (CHF), sympathetic overactivity correlates with the exacerbation of cardiac performance. To test the hypothesis that the cardiac sympathetic nerve density dramatically changes with the acceleration of circulating norepinephrine (NE) concentration, we investigated the temporal association of nerve growth factor (NGF) expression in the heart and cardiac sympathetic nerve density during the development of CHF in the continuous NE-infused rats. The animals were analyzed at 0-, 1-, 3-, 7-, 14-, and 28-day after implantation of osmotic pump at a rate of 0.05 mg/kg/hr. The cardiac performance was temporally facilitated in NE-exposed rats at 3-day in accordance with the sympathetic hyper-innervation induced by the augmentation of NGF mRNA expression in the heart. In NE-treated rats, left ventricular end-diastolic pressure was significantly increased after 7-day and marked left ventricular hypertrophy and systemic fluid retention were observed at 28-day. CHF-induced sympathetic overactivity further increased plasma NE concentration in NE-treated rats and finally reached to 16.1+/-5.6 ng/ml at 28-day (control level was 0.39+/-0.1 ng/ml, p<0.01). In the decompensated CHF rats at 28-day, the NGF mRNA expression was conspicuously reduced concomitant with the obvious nerve fiber loss confirmed by the immunostaining of nerve axonal marker, PGP9.5 and sympathetic neuron marker, tyrosine hydroxylase. This resulted in the attenuated tissue NE contents and the exacerbating cardiac performance. The cardiac sympathetic fiber loss was also confirmed in NE-exposed DBH (dopamine beta-hydroxylase)-Cre/Floxed-EGFP (enhanced green fluorescent protein) mice with severe CHF, in which sympathetic nerve could be traced by EGFP. Our results suggest that the cardiac sympathetic nerve density is strictly regulated by the NGF expression in the heart and long-exposure of high plasma NE concentration caused myocardial NGF reduction, following sympathetic fiber loss in severe CHF animals.