Prenatal nicotine exposure increases osteoarthritis susceptibility in male elderly offspring rats via low-function programming of the TGFß signaling pathway.

Epidemiological investigations indicate that effects related to prenatal adverse environments on the organs of the offspring could continue to adulthood. This study intends to confirm that prenatal nicotine exposure (PNE) increases the susceptibility of osteoarthritis (OA) in the male offspring, and to explore the potential intrauterine programming mechanism. During pregnancy, rats were divided into a PNE group and a control group. After birth, rats were given a high-fat diet for 6 months and long-distance running for 6 weeks. The rats were euthanized at 18 months after birth (PM18) and on gestational day 20 (GD20), respectively. Knee joints were collected for histochemistry, immunohistochemistry, and quantitative polymerase chain reaction (qPCR) assays. Histological analyses and the Mankin's score showed increased cartilage destruction and accelerated OA progression in adult offspring from the PNE group. Immunohistochemistry results showed decreased expression of transforming growth factor beta (TGFß) signaling pathway. Furthermore, the expression of apoptosis factors (caspase-3 and caspase-8), inflammatory factors [interleukin (IL)-1, IL-6] and matrix degradation enzymes [matrix metalloproteinase (MMP)-3, MMP-13] were also significantly increased. Traced back to the intrauterine period, it was found that the number of chondrocytes and the contents of Col2A1 and aggrecan in the matrix in the PNE group were decreased. And, the expression of the TGFß signaling pathway was inhibited. These results suggested that PNE enhanced the susceptibility of OA in male elderly offspring rats by down-regulating TGFß signaling, which increased articular cartilage local inflammation, matrix degradation, and cell apoptosis. This study confirmed the developmental origin of OA, and clarified the congenital and the living environment impact on the occurrence and development of OA. Our findings provide a theoretical and experimental basis for OA early prevention.

Potential role of andrographolide in the proliferation of osteoblasts mediated by the ERK signaling pathway.

The aim of the present study was to explore the effects of andrographolide (AG) and the ERK signaling pathway on the proliferation of osteoblasts (OBs) in vitro. The calvarial OBs from Sprague Dawley (SD) rats were collected and treated at different concentrations of AG and U0126. The concentrations of AG were measured by colorimetry. Based on different treatment methods, the cells were separated into four groups: control group, U0126 group, AG group, and AG+U0126 group. The cells were cultured for 24h, 48h and 72h. An inverted phase contrast microscope was used to observe the morphologies of treated OBs. The MTT assay was performed to plot OB proliferation curves, and to measure the changes in alkaline phosphatase and hydroxyproline contents after U0126 treatments. The expressions of proliferating cell nuclear antigen (PCNA), Ki67, core binding factor alpha-1 (Cbfa1), type I collagen (Col I), osterix (OSX), p38, extracellular signal regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) were measured by fluorescent quantitative polymerase chain reaction (PCR) and Western blotting. In different cell groups, the in vitro proliferation rates of OBs reached the highest at an AG concentration of 20µmol/L, and the amounts of alkaline phosphatase, hydroxyproline, PCNA, Ki67, Cbfa1, Col I, OSX, and ERK were significantly higher than at other concentrations (all P<0.05). U0126 intervention significantly decreased the expressions of these factors (all P<0.05). At the meantime, p38 and JNK were not affected by AG and were only inhibited by U0126. In conclusion, ERK played an important role in mediating the functions of AG in the proliferation of OBs, indicating that the ERK signaling pathway may be the main pathway through which AG exerts its effects.