Ryanodine receptor 1 mediated dexamethasone-induced chondrodysplasia in fetal rats

Activation of the PGC-1α-mediated mitochondrial glutamine metabolism pathway attenuates female offspring osteoarthritis induced by prenatal excessive prednisone

Osteoarthritis is a chronic, age-related joint disease. Previous studies have shown that osteoarthritis develops during intrauterine development. Prednisone is frequently used to treat pregnancies complicated by autoimmune diseases. However, limited research has been conducted on the enduring effects of prednisone use during pregnancy on the offspring. In this study, we investigated the effect of excessive prednisone exposure on cartilage development and susceptibility to osteoarthritis in the offspring. We found that prenatal prednisone exposure (PPE) impaired cartilage extracellular matrix (ECM) synthesis, resulting in poor cartilage pathology in female offspring during the adult period, which was further exacerbated after long-distance running stimulation. Additionally, PPE suppressed cartilage development during the intrauterine period. Tracing back to the intrauterine period, we found that Pred, rather than prednisone, decreased glutamine metabolic flux, which resulted in increased oxidative stress, and decreased histone acetylation, and expression of cartilage phenotypic genes. Further, PGC-1α-mediated mitochondrial biogenesis, while PPE caused hypermethylation in the promoter region of PGC-1α and decreased its expression in fetal cartilage by activating the glucocorticoid receptor, resulting in a reduction of glutamine flux controlled by mitochondrial biogenesis. Additionally, overexpression of PGC-1α (either pharmacological or through lentiviral transfection) reversed PPE- and Pred-induced cartilage ECM synthesis impairment. In summary, this study demonstrated that PPE causes chondrodysplasia in female offspring and increases their susceptibility to postnatal osteoarthritis. Hence, targeting PGC-1α early on could be a potential intervention strategy for PPE-induced osteoarthritis susceptibility.

Stage-, dose-, and course-dependent inhibition of prenatal amoxicillin exposure on fetal articular cartilage development in fetal mice

Amoxicillin is widely used in the treatment of infectious diseases during pregnancy; however, the effects of prenatal amoxicillin exposure (PAE) on fetal development remain largely unknown. Therefore, this study aimed to investigate the toxic effects of PAE on fetal cartilage at different stage-, dose-, and course. Pregnant Kunming mice were orally administered 300 mg/kg·d (converted from clinical dose) amoxicillin on gestational days (GD) 10-12 or 16-18 (mid or late pregnancy stage), 150 or 300 mg/kg.d amoxicillin on GD16-18 (different doses), 300 mg/kg·d amoxicillin on GD16 (single course) or 16-18 (multiple courses), respectively. The fetal articular cartilage of the knee was collected on GD18. The number of chondrocytes and the expression of matrix synthesis/degradation, proliferation/apoptosis-related markers, and the TGF-β signaling pathway were detected. The results showed that the number of chondrocytes and the expression of matrix synthesis markers were reduced in male fetal mice treated with PAE (GD16-18, 300 mg/kg.d, single course and multiple courses), whereas the above indices in female mice showed no changes. The inhibited expression of PCNA, increased expression of Caspase-3, and down-regulated expression of the TGF-β signaling pathway were found in male PAE fetal mice. Accordingly, PAE exerted its "toxic effect window" on the knee cartilage development in male fetal mice, which manifested as reduced chondrocyte number and inhibited expression of matrix synthesis at a clinical dose of multiple courses in the late pregnancy stage. This study provides a theoretical and experimental basis for elucidating the risk of chondrodevelopmental toxicity associated with amoxicillin during pregnancy.

Intrauterine programming of cartilaginous 11β-HSD2 induced by corticosterone and caffeine mediated susceptibility to adult osteoarthritis

Our previous study reported that prenatal caffeine exposure (PCE) could induce chondrodysplasia and increase the susceptibility to osteoarthritis in offspring rats. However, the potential mechanisms and initiating factors remain unknown. This study aims to investigate whether 11β-HSD2, a glucocorticoid-metabolizing enzyme, is involved in the susceptibility of osteoarthritis induced by PCE and to further explore its potential mechanisms and initiating factors. Firstly, we found that PCE reduced cartilage matrix synthesis (aggrecan/Col2a1 expression) in male adult offspring rats and exhibited an osteoarthritis phenotype following chronic stress, which was associated with persistently reduced H3K9ac and H3K27ac levels at the promoter of 11β-HSD2 as well as its expression in the cartilage from fetus to adulthood. The expression of 11β-HSD2, aggrecan and Col2a1 were all decreased by corticosterone in the fetal chondrocytes, while overexpression of 11β-HSD2 could partially alleviate the decrease of matrix synthesis induced by corticosterone in vitro. Furthermore, the glucocorticoid receptor (GR) activated by glucocorticoids directly bonded to the promoter region of 11β-HSD2 to inhibit its expression. Meanwhile, the activated GR reduced the H3K9ac and H3K27ac levels of 11β-HSD2 by recruiting HDAC4 and promoting GR-HDAC4 protein interaction to inhibit the 11β-HSD2 expression. Moreover, caffeine could reduce the expression of 11β-HSD2 by inhibiting the cAMP/PKA signaling pathway but without reducing the H3K9ac and H3K27ac levels of 11β-HSD2, thereby synergistically enhancing the corticosterone effect. In conclusion, the persistently reduced H3K9ac and H3K27ac levels of 11β-HSD2 from fetus to adulthood mediated the inhibition of cartilage matrix synthesis and the increased susceptibility to osteoarthritis. This epigenetic programming change in utero was induced by glucocorticoids with synergistic effect of caffeine.

Effects of the Leptin-Mediated MAPK/ERK Signaling Pathway on Collagen II Expression in Knee Cartilage of Newborn Male Mice from Obese Maternal Offspring

Epidemiological data suggest that various noncommunicable diseases develop as a result of altered maternal metabolic and physiological status due to exposure to several adverse factors during pregnancy. However, evidence for intrauterine exposure factors and mechanisms underlying the origin of early cartilage disease in chronic osteoarthritic disease is still lacking. In this study, we found that persistent overnutrition during pregnancy in obese mothers led to cartilage damage in neonatal male mice. This was mainly characterized by increased apoptosis with decreased expression of chondrocyte collagen II and low expression of Runx family transcription factor 2 (RUNX2) and SRY-box transcription factor 9 (SOX9). This reduction was also found to be associated with high leptin expression in newborn male mice of obese maternal offspring. Furthermore, the administration of leptin and mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase (ERK) inhibitors in primary chondrocytes showed that leptin mediated MAPK/ERK signaling activation and thus affected the key regulators of cartilage matrix metallopeptidase 1 (MMP1) and tissue inhibitor of metalloproteinase 1 (TIMP1), thereby altering the expression of collagen II in mouse cartilage. Altogether, this study provided insights into the molecular mechanisms of cartilage-related disease development and also new clues and evidence for the fetogenetic origin of cartilage diseases.

Glucocorticoid caused lactic acid accumulation and damage in human chondrocytes via ROS-mediated inhibition of Monocarboxylate Transporter 4

Osteoarthritis (OA) is a common joint disease lacking effective treatments. Dexamethasone (Dex) is often used to relieve joint pain. However, the adverse effects of Dex on cartilage can't be ignored. This study aimed to investigate the effect of Dex on articular cartilage and its mechanism by in vitro and in vivo experiments. The results showed that intra-articular injection with Dex damaged the matrix synthesis of cartilage. In vitro, Dex induced human chondrocytes mitochondrial dysfunction and increased reactive oxygen species (ROS) level, while down-regulated or unchanged key glycolysis genes, but increased lactic acid (LA) concentration. It was showed that high concentrations of LA induced chondrocytes apoptosis. Mechanistically, monocarboxylate transporter 4 (MCT4) was inhibited by Dex and had a significant negative correlation with ROS level. Further results showed that the trimethyl-histone H3-K4 (H3K4me3) level of MCT4 was reduced by Dex, and the ROS scavenger N-Acetyl-L-cysteine (NAC) and α-ketoglutarate (α-KG) alleviated the Dex-induced obstruction of matrix synthesis and high level of ROS by up-regulating the H3K4me3 level of MCT4 and its expression. In conclusion, Dex exhibited harm to cartilage, shown as mitochondrial dysfunction and increased ROS. The latter further caused LA accumulation in chondrocytes via decreasing the H3K4me3 level of MCT4 and its expression, which may account for the long-term side effects of Dex on chondrocytes. And α-KG may be used as an auxiliary drug to weaken the toxic effect of Dex on cartilage.