Tocotrienol regulates osteoclastogenesis in rheumatoid arthritis

Background/Aims@#The present study aimed to investigate whether tocotrienol regulates interleukin 17 (IL-17)-induced osteoclastogenesis in rheumatoid arthritis (RA). @*Methods@#We evaluated the effect of tocotrienol on IL-17-induced receptor activator of nuclear factor kappa B ligand (RANKL) production using RA fibroblast-like synoviocyte (FLS), together with real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Osteoclast differentiation was confirmed after culturing IL-17-treated RA FLS and Th17 cells with tocotrienol and monocytes. We analyzed the suppressive effect of tocotrienol on Th17 cells percentage or Th17-cytokine levels among peripheral blood mononuclear cells using flow cytometry. @*Results@#We found that IL-17 stimulated FLS to produce RANKL and tocotrienol decreased this IL-17-induced RANKL production. Tocotrienol decreased the IL-17-induced activation of mammalian target of rapamycin, extracellular signal-regulated kinase, and inhibitor of kappa B-alpha. When monocytes were incubated with IL-17, RANKL, IL-17-treated FLS or Th17 cells, osteoclasts were differentiated and tocotrienol decreased this osteoclast differentiation. Tocotrienol reduced Th17 cell differentiation and the production of IL-17 and sRANKL; however, tocotrienol did not affect Treg cell differentiation. @*Conclusions@#Tocotrienol inhibited IL-17- activated RANKL production in RA FLS and IL-17-activated osteoclast formation. In addition, tocotrienol reduced Th17 differentiation. Therefore, tocotrienol could be a new therapeutic choice to treat bone destructive processes in RA.

Intravenous Immunoglobulin Controls Th17 Cell-Mediated Osteoclastogenesis

The purpose of this study was to determine the regulatory role of intravenous Ig (IVIg) in Th17 cytokine–induced RANK ligand (RANKL) expression and osteoclast (OC) differentiation from OC precursors (pre-OC). Human CD14⁺ monocytes were isolated and stimulated by Th17 cytokines (IL-17, IL-21, and IL-22) and RANKL expression was investigated using a real-time PCR. CD14⁺ monocytes were incubated with RANKL, Th17 cytokines, and M-CSF, with/without IVIg, and OC differentiation was determined by counting tartrate-resistant acid phosphatase-positive multinucleated cells. OC differentiation was investigated after monocytes were cocultured with Th17 cells in the presence of IVIg. Th17 cell differentiation was determined using enzyme-linked immunosorbent assay and flow cytometry after CD4⁺ T cells were cultured with IVIg under Th17 condition. Th17 cytokines stimulated monocytes to express RANKL and IVIg suppressed the Th17 cytokine-induced RANKL expression. OCs were differentiated when pre-OC were cocultured with RANKL or Th17 cytokines and IVIg reduced the osteoclastogenesis. IVIg also decreased osteoclastogenesis when pre-OC were cocultured with Th17 cells. IVIg decreased both Th17 and Th1 cell differentiation while it did not affect Treg cell differentiation. In summary, IVIg inhibited Th17 cytokine-induced RANKL expression and OC differentiation. IVIg reduced osteoclastogenesis when monocytes were cocultured with Th17 cells. IVIg also reduced Th17 polarization. IVIg could be a new therapeutic option for Th17 cell–mediated osteoclastogenesis.

Learning Curves for Colonoscopy: A Prospective Evaluation of Gastroenterology Fellows at a Single Center

BACKGROUND/AIMS: Colonoscopy training programs and the minimal experience with colonoscopy required to be considered technically competent are not well established. The aim of this study was to determine the colonoscopy learning curves and factors associated with this difficult procedure at a single center. METHODS: A total of 3,243 colonoscopies were performed by 12 first-year gastroenterology fellows, and various clinical factors were assessed prospectively for 22 months. Acquisition of competence (success rate) was evaluated based on two objective criteria: (i) the adjusted completion rate (>90%) and (ii) cecal intubation time (20 minutes). Surgery of the uterus and ovaries was significantly correlated with delayed cecal intubation time, but not after sufficient colonoscopy experience. CONCLUSIONS: The minimum number of procedures to reach technical competence was 200. The cecal intubation time was longer in female and older patients.