All-trans retinoic acid (ATRA), an active form of vitamin A, exerts immunomodulatory functions. In this study, we examined the immune potentiating effect of ATRA on bacterial flagellin-induced NF-κB activation and proinflammatory cytokine production in human monocytic cell line THP-1. ATRA treatment significantly enhanced the flagellin-induced NF-κB/AP-1 activity in THP-1 via the RAR/RXR pathway. Similarly, ATRA enhanced the expression and production of TNF-αand IL-1βin THP-1 cells upon flagellin challenge. The cell surface expression of toll-like receptor 5 (TLR5), which is the receptor for bacterial flagellin, was significantly reduced by ATRA in a concentration- and time-dependent manner. To determine the mechanisms underlying the ATRA-enhanced immune response against bacterial flagellin despite the reduced cell surface expression of TLR5 in ATRA-treated THP-1, we examined the cell surface expression of CD14, which has been proposed to be a TLR co-receptor that enhances the response to microbial components. The cell surface expression of CD14 was significantly enhanced by ATRA treatment, especially in the presence of flagellin. Anti-CD14 antibody treatment prior to ATRA and flagellin treatments completely abolished ATRA-enhanced TNF-αand IL-1βproduction. Our results suggest that ATRA enhances flagellin-stimulated proinflammatory responses in human monocyte THP-1 cells by upregulating CD14 in a RAR/RXR-dependent manner.

Regulatory macrophages (Mreg) are a special cell type that present a potential therapeutic strategy for various inflammatory diseases. In vitro, Mreg generation mainly takes 7–10 days of treatment with chemicals, including cytokines. In the present study, we established a new approach for Mreg generation using a three-dimensional (3D) micropatterned polydimethylsiloxane (PDMS) surface coated with a natural biopolymer adhesive polydopamine (PDA) and the common cell adhesion peptide motif arginylglycylaspartic acid (RGD). The 3D PDMS surfaces were fabricated by photolithography and soft lithography techniques and were subsequently coated with an RGD+PDA mixture to form a surface that facilitates cell adhesion. Human monocytes (THP-1 cells) were cultured on different types of 2D or 3D micropatterns for four days, and the cell morphology, elongation, and Mreg marker expression were assessed using microscopic and flow cytometric analyses. The cells grown on the PDA+RGD-coated 3D micropatterns (20-µm width/20-µm space) exhibited the most elongated morphology and strongest expression levels of Mreg markers, such as CD163, CD206, CD209, CD274, MER-TK, TREM2, and DHRS9. The present study demonstrated that PDA+RGD-coated 3D PDMS micropatterns successfully induced Mreg-like cells from THP-1 cells within four days without the use of cytokines, suggesting a time- and cost-effective method to generate Mreg-like cells in vitro.

Urinary tract infection (UTI) is one of the most common bacterial infections in infants less than age 1 year. UTIs frequently recur and result in long-term effects include sepsis and renal scarring. Uropathogenic Escherichia coli (UPEC), the most prevalent organism found in UTIs, can cause host inflammation via various virulence factors including hemolysin and cytotoxic necrotizing factors by inducing inflammatory cytokines such as interleukin (IL)-1β. However, the ability of each UPEC organism to induce IL-1β production may differ by strain. Furthermore, the correlation between differential IL-1β induction and its relevance in pathology has not been well studied. In this study, we isolated UPEC from children under age 24 months and infected bone-marrow derived macrophages with the isolates to investigate secretion of IL-1β. We found that children with higher concentrations of C-reactive protein (CRP) were more likely to harbor phylotype B2 UPEC strains that induced more IL-1β production than phylotype D. We also observed a significant correlation between serum CRP level and in vitro IL-1β induction by phylotype B2 UPEC bacteria. Our results highlight the diversity of UPEC in terms of IL-1β induction capacity in macrophages and suggest a potential pathogenic role in UTIs by inducing inflammation in infants.

Protective effects of electromagnetic fields (EMFs) against oxygen and glucose deprivation (OGD)induced human mesenchymal stem cell (MSC) death were studied. Cell survival, intracellular calcium and ROS/RNS levels were measured after culturing MSCs for 3 h under OGD with or without EMF exposure. The survival rate of cells cultured under OGD condition was significantly reduced compared to control cells, while cells cultured in OGD with 10 Hz/1 mT EMF exposure had higher survival ratio than that in equivalent non-exposed cells. This protective effect of EMF was not observed at different frequency/intensity combinations such as 10 Hz/0.01 mT, 10 Hz/0.1 mT, 50 Hz/1 mT and 100 Hz/1 mT. ROS/ RNS levels of cells cultured under OGD conditions significantly increased compared to the control level while 10 Hz/1 mT EMF alleviated this effect. Intracellular calcium levels in OGD group were higher than control while those in OGD plus 10 Hz/1 mT EMF group were significantly lower than OGD group. Addition of Ca 2+ chelator promoted protective effects of EMF against OGD-induced MSC death. Our results suggest that 10 Hz/1 mT EMF exposure protects MSCs from OGD-induced cell death and the underlying mechanisms of the protection are reduction of intracellular levels of Ca 2+ and ROS/RNS.

Introduction: Typhoid incidence in children is higher in urban areas than in rural areas of Bangladesh. This study examined whether healthy urban children harboured higher levels of Salmonella genes than healthy rural children. Methodology: Stool samples from 140 children were studied: 70 from rural areas and 70 from urban metropolitan areas. Results: The stool samples of urban children contained more Salmonella genes (median 4, IQR 3-4) than those of rural children (median 3, IQR 3-4). This suggests that urban Bangladeshi children have more Salmonella genes in their guts than rural children. Especially, in those under 12 months of age, the Salmonella gene prevalence in urban children was unique. They had more Salmonella genes (median 4, IQR 4-5) than rural children in the same age group (median 3, IQR 2.5-4). We also found more Salmonella genes in urban children who drank tap water (median 4, IQR 3-5) than in rural children whose water source was tube well water (median 3, IQR 2-4) and boiled pond water (median 3, IQR 3-3.5). However, there was no significant difference of Salmonella genes between urban children who drank tap-water and children whose water source was a tube well (median 4, IQR 3-4). Conclusions: These data suggest that the urban environment, including the drinking water supply system, increases the likelihood of healthy children in urban areas harbouring more potentially pathogenic Salmonella organisms in their gut than found in rural healthy children.