Genipin Analogue (G300) Inhibits Adipogenic Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells through the Suppression of Adipogenic Promoting Factors

While obesity is a well-known health threatening condition worldwide, effective pharmacological interventions for obesity suppression have been limited due to adverse effects. Therefore, it is important to explore alternative medical treatments for combating obesity. Inhibition of the adipogenesis process and lipid accumulation are critical targets for controlling and treating obesity. Gardenia jasminoides Ellis is a traditional herbal remedy for various ailments. A natural product from its fruit, genipin, has major pharmacological properties; it is anti-inflammatory and antidiabetic. We investigated the effects of a genipin analogue, G300, on adipogenic differentiation in human bone marrow mesenchymal stem cells (hBM-MSCs). G300 suppressed the expression of adipogenic marker genes and adipokines secreted by adipocytes at concentrations of 10 and 20 μM, which effectively reduced the adipogenic differentiation of hBM-MSCs and lipid accumulation in adipocytes. It also improved adipocyte function by lowering inflammatory cytokine secretion and increasing glucose uptake. For the first time, we show that G300 has the potential to be a novel therapeutic agent for the treatment of obesity and its related disorders.

Vitamin C supplementation reduces expression of circulating miR-451a in subjects with poorly controlled type 2 diabetes mellitus and high oxidative stress

Background

Vitamin C is an essential element required for normal metabolic function. We investigated the effect of vitamin C supplementation on circulating miRNA (miR) expression in subjects with poorly controlled type 2 diabetes mellitus (T2DM). Changes in miR expression were also correlated with clinical measures of disease.

Methods

Pre- and post-vitamin C supplementation samples from five participants who had increased vitamin C levels, improved oxidative status and polymorphonuclear (PMN) function after receiving 1,000 mg of vitamin C daily for six weeks were screened for miRNA expression using the NanoString miRNA assay. Differences in miRNA expression identified from the miRNA screen were validated by qRT-PCR.

Results

Four miRNAs showed significantly different expression post-vitamin C supplementation relative to baseline, including the down-regulation of miR-451a (−1.72 fold change (FC), p = 0.036) and up-regulation of miR-1253 (0.62 FC, p = 0.027), miR-1290 (0.53 FC, p = 0.036) and miR-644a (0.5 FC, p = 0.042). The validation study showed only miR-451a expression was significantly different from baseline with vitamin C supplementation. MiR-451a expression was negatively correlated with vitamin C levels (r =  − 0.497, p = 0.049) but positively correlated with levels of malondialdehyde (MDA) (r = 0.584, p = 0.017), cholesterol (r = 0.564, p = 0.022) and low-density lipoproteins (LDL) (r = 0.522, p = 0.037). Bioinformatics analysis of the putative target genes of miR-451a indicated gene functions related to signaling pathways involved in cellular processes, such as the mammalian target of rapamycin (mTOR) signaling pathway.

Conclusions

Vitamin C supplementation altered circulating miR-451a expression. The results from this pilot study suggest that miRNAs could be used as biomarkers to indicate oxidative status in subjects with T2DM and with poor glycemic control and could lead to a novel molecular strategy to reduce oxidative stress in T2DM.

Enhancement of vitamin C on PMN function in healthy individuals

Vitamin C (ascorbic acid, ascorbate) promotes immune cell activities by supporting various cellular functions especially, in neutrophils or polymorphonuclear (PMN) leukocytes, which play an important role in bacterial infection and acute inflammation. Little data have been reported in impact of vitamin C on PMN function during bacterial phagocytosis in healthy individuals. Here, we have elucidated the effect of vitamin C on PMN phagocytosis and oxidative burst to Staphylococcus aureus by whole blood assay and flow cytometry after pre-incubation without and with vitamin C in vary concentrations. The results showed that vitamin C concentration at 20 mM induced a significant increase phagocytosis (p-value=0.03) and had trend to significant increase oxidative burst (p-value=0.06) while vitamin C concentration of 30 mM showed significant increase both phagocytosis and oxidative burst (p-value=0.04 and 0.02, respectively) at only 15 min of exposure to the bacteria. As a minimal concentration that can increase phagocytosis, we selected vitamin C at 20 mM as optimal concentration to investigate more data by enrollment of healthy volunteers (n=17). The results revealed significant difference both phagocytosis and oxidative burst after 20 mM vitamin C pre-incubation (p<0.0001). In conclusion, we showed that vitamin C at 20 mM can boost phagocytosis and oxidative burst of neutrophils in healthy adults within 15 min after bacterial exposure. This rapid activation may be applied to fight bacterial infection. Nevertheless, further research in clinical trial and underlying mechanisms await further studies.