Lipopolysaccharide (LPS) promotes osteoclast differentiation and activation by enhancing the MAPK pathway and COX-2 expression in RAW264.7 cells.

Bone degradation is a serious complication of chronic inflammatory diseases such as septic arthritis, osteomyelitis and infected orthopedic implant failure. At present, effective therapeutic treatments for lipopolysaccharide (LPS)-induced bone destruction are limited to antibiotics and surgical repair in chronic inflammatory diseases. The present study aimed to evaluate the mechanism of LPS on osteoclast differentiation and activation. RAW264.7 cells were non-induced, or induced by the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) and macrophage-colony stimulating factor (M-CSF), and then treated with LPS. Following treatment, the number of osteoclasts and cell viability were measured. The expression of osteoclast-related genes including tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinase-9 (MMP-9), cathepsin K (CK), carbonic anhydrase II (CAII) and cyclooxygenase-2 (COX-2) was determined by RT-PCR. Protein levels of RANK, tumor necrosis factor receptor-associated factor 6 (TRAF6), COX-2 and mitogen-activated protein kinases (MAPK) were measured using western blotting assays. LPS promoted osteoclast differentiation of RAW264.7 cells and differentiated osteoclasts. LPS significantly increased mRNA expression of osteoclast-related genes in RAW264.7 cells. Differentiated osteoclasts were treated with LPS (100 ng/ml) and the results showed a significantly increased mRNA expression of osteoclast-related genes and protein levels of RANK, TRAF6 and COX-2. Furthermore, LPS at 100 ng/ml significantly promoted the MAPK pathway including increasing the phosphorylation of c-Jun N-terminal kinases (JNK) and the phosphorylation of the extracellular signal-regulated kinase (ERK1/2). In conclusion, LPS promoted osteoclast differentiation and activation by enhancing RANK signaling and COX-2 expression. LPS also promoted osteoclast differentiation via activation of the JNK and ERK1/2 cell proliferation pathways.

[Effects of carvedilol on cardiomyocyte apoptosis in autoimmune myocarditis in mice].

OBJECTIVE: To observe the effects of carvedilol on the expression of Bcl-2, Bax and Fas in autoimmune myocarditis (AM). METHODS: A total of 60 inbred male BALB/C mice 4 - 5 weeks of age were divided at random into 3 groups as follows: AM group (n = 20), carvedilol group (n = 20) and control group (n = 20). The mice were sacrificed after gathering blood specimens by taking out the eyeballs and hearts tissue. The histological and ultrastructural changes were observed under light microscope and electron microscope. The concentrations of cardiac troponin I (cTn I) were detected by chemiluminescence immunoassay (CLIA). Immunohistochemistry (IHC) was performed to analyze the contents of Bcl-2, Bax and Fas, TUNEL to detect the apoptotic index in myocardial cells. RESULTS: There were large number of lymphocyte and monocyte infiltrates under light microscope and karyopyknosis and chromatin gathered along the nuclear membrane under electron microscope in AM group. There were no inflammations and chromatin gathering in group C. Compared with control group, the Bcl-2, Bax and Fas protein expression significantly elevated in AM group (23.48 ± 2.24 vs. 6.64 ± 1.60, 26.15 ± 2.02 vs. 5.09 ± 0.85, 21.22 ± 3.62 vs. 5.86 ± 1.37, P < 0.01). The histopathologic scores (2.60 ± 0.31 vs. 2.02 ± 0.26, P < 0.05) and karyopyknosis of carvedilol group decreased as compared with AM group. The Bcl-2, Bax and Fas protein expression (17.13 ± 1.94 vs. 23.48 ± 2.24, 17.66 ± 2.62 vs. 26.15 ± 2.02, 16.79 ± 2.83 vs. 21.22 ± 3.62, P < 0.05), AI [(16.61 ± 4.67)% vs. (24.51 ± 4.70)%, P < 0.05] and contents of cTnI [(1.878 ± 0.48) ng/ml vs. (1.102 ± 0.23) ng/ml, P < 0.05] also decreased in carvedilol group compared with AM group. CONCLUSION: Carvedilol could protect against AM by alleviating cardiomyocyte apoptosis.

[Overexpression of SERCA2a by gene transfer enhances myocardial systolic function in canines].

The present study is aimed to study the effect of sarcoplasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) gene transfer on the contractile function of isolated cardiomyocytes of canines. The cardiomyocytes were isolated with collagenases. The isolated cardiac cells were divided into untransfected group, empty vector group and SERCA2a-transfected group. Recombinant adenovirus vector carrying enhanced green fluorescent protein gene was used for SERCA2a gene delivery. The expression of SERCA2a protein in cardiomyocytes was determined by Western blot. Contractile function of cardiomyocytes was measured with motion edge-detection system of single cell at 48 h after transfection. The results showed, compared with untransfected group, SERCA2a protein level, percentage of peak contraction amplitude under normal condition, percentages of peak contraction amplitude under Ca(2+) or isoproterenol stimulation, time-to-peak contraction (TTP) and time-to-50% relaxation (R50) in SERCA2a-transfected group all increased significantly. While all the above indices in empty vector group did not show any differences with those in untransfected group. These results suggest that the overexpression of SERCA2a by gene transfer may enhance the contraction function of canine myocardial cells.