Microscopic Colitis with Macroscopic Endoscopic Findings

Microscopic Colitis (MC) is characterized by chronic watery diarrhea, grossly normal appearing colonic mucosa during conventional white light endoscopy, and biopsy showing microscopic inflammation. We report a case of collagenous colitis with gross endoscopic findings

AF17 Competes With AF9 for Binding to DOT1A to up-Regulate Transcription of Epithelial NA\u3csup\u3e+\u3c/sup\u3e Channel α

We previously reported that Dot1a*AF9 complex represses transcription of the epithelial Na+ channel subunit α (α-ENaC) gene in mouse inner medullary collecting duct mIMCD3 cells and mouse kidney. Aldosterone relieves this repression by down-regulating the complex through various mechanisms. Whether these mechanisms are sufficient and conserved in human cells or can be applied to other aldosterone-regulated genes remains largely unknown. Here we demonstrate that human embryonic kidney 293T cells express the three ENaC subunits and all of the ENaC transcriptional regulators examined. These cells respond to aldosterone and display benzamil-sensitive Na+ currents, as measured by whole-cell patch clamping. We also show that AF17 and AF9 competitively bind to the same domain of Dot1a in multiple assays and have antagonistic effects on expression of an α-ENaC promoter-luciferase construct. Overexpression of Dot1a or AF9 decreased mRNA expression of the ENaC subunits and their transcriptional regulators and reduced benzamil-sensitive Na+ currents. AF17 over-expression caused the opposite effects, accompanied by redirection of Dot1a from the nucleus to the cytoplasm and reduction in histone H3 K79 methylation. The nuclear export inhibitor leptomycin B blocked the effect of AF17 overexpression on H3 K79 hypomethylation. RNAi-mediated knockdown of AF17 yielded nuclear enrichment of Dot1a and histone H3 K79 hypermethylation. As with AF9, AF17 displays nuclear and cytoplasmic co-localization with Sgk1. Therefore, AF17 competes with AF9 to bind Dot1a, decreases Dot1a nuclear expression by possibly facilitating its nuclear export, and relieves Dot1a*AF9-mediated repression of α-ENaC and other target genes

Toll-Like Receptor 9 Is Required for Opioid-Induced Microglia Apoptosis

Opioids have been widely applied in clinics as one of the most potent pain relievers for centuries, but their abuse has deleterious physiological effects beyond addiction. However, the underlying mechanism by which microglia in response to opioids remains largely unknown. Here we show that morphine induces the expression of Toll-like receptor 9 (TLR9), a key mediator of innate immunity and inflammation. Interestingly, TLR9 deficiency significantly inhibited morphine-induced apoptosis in microglia. Similar results were obtained when endogenous TLR9 expression was suppressed by the TLR9 inhibitor CpGODN. Inhibition of p38 MAPK by its specific inhibitor SB203580 attenuated morphine-induced microglia apoptosis in wild type microglia. Morphine caused a dramatic decrease in Bcl-2 level but increase in Bax level in wild type microglia, but not in TLR9 deficient microglia. In addition, morphine treatment failed to induce an increased levels of phosphorylated p38 MAPK and MAP kinase kinase 3/6 (MKK3/6), the upstream MAPK kinase of p38 MAPK, in either TLR9 deficient or µ-opioid receptor (µOR) deficient primary microglia, suggesting an involvement of MAPK and µOR in morphine-mediated TLR9 signaling. Moreover, morphine-induced TLR9 expression and microglia apoptosis appears to require μOR. Collectively, these results reveal that opioids prime microglia to undergo apoptosis through TLR9 and µOR as well. Taken together, our data suggest that inhibition of TLR9 and/or blockage of µOR is capable of preventing opioid-induced brain damage

Case Report Microscopic Colitis with Macroscopic Endoscopic Findings

Microscopic Colitis (MC) is characterized by chronic watery diarrhea, grossly normal appearing colonic mucosa during conventional white light endoscopy, and biopsy showing microscopic inflammation. We report a case of collagenous colitis with gross endoscopic findings

Hematopoietic Stem-Progenitor Cells Restore Immunoreactivity and Improve Survival in Late Sepsis

Sepsis progresses from an early/acute hyperinflammatory to a late/chronic hypoinflammatory phase with immunosuppression. As a result of this phenotypic switch, mortality in late sepsis from persistent primary infection or opportunistic new infection often exceeds that in acute sepsis. Emerging data support that persistence of the hypoinflammatory (hyporesponsive) effector immune cells during late sepsis might involve alterations in myeloid differentiation/maturation that generate circulating repressor macrophages that do not readily clear active infection. Here, we used a cecal ligation and puncture (CLP) murine model of prolonged sepsis to show that adoptive transfer of CD34 + hematopoietic stem-progenitor cells after CLP improves long-term survival by 65%. CD34 + cell transfer corrected the immunosuppression of late sepsis by (i) producing significantly higher levels of proinflammatory mediators upon ex vivo stimulation with the Toll-like receptor 4 (TLR4) agonist lipopolysaccharide, (ii) enhancing phagocytic activity of peritoneal macrophages, and (iii) clearing bacterial peritonitis. Improved immunity by CD34 + cell transfer decreased inflammatory peritoneal exudate of surviving late-sepsis mice. Cell tracking experiments showed that the transferred CD34 + cells first appeared in the bone marrow and then homed to the spleen and peritoneum. Because CD34 + cells did not affect the early-phase hyperinflammatory response, it is likely that the newly incorporated pluripotent CD34 + cells differentiated into competent immune cells in blood and tissue, thereby reversing or replacing the hyporesponsive endotoxintolerant cells that occur and persist after the initiation of early sepsis

β-Arrestin 2 Negatively Regulates Toll-Like Receptor 4 (TLR4)-Triggered Inflammatory Signaling via Targeting p38 MAPK and Interleukin 10

The control of IL-10 production in Toll-like receptor (TLR) signals remains to be elucidated. Here, we report that β-arrestin 2 positively regulates TLR-triggered IL-10 production in a p38 mitogen-activated protein kinase (MAPK)-dependent mechanism. In vitro studies with cells including peritoneal macrophages and HEK293/TLR4 cells have demonstrated that β-arrestin 2 forms complexes with p38 and facilitates p38 activation after lipopolysaccharide (LPS) stimulation. Deficiency of β-arrestin 2 and inhibition of p38 MAPK activity both ameliorate TLR4-stimulated IL-10 response. Additionally, in vivo experiments show that mice lacking β-arrestin 2 produce less amount of IL-10, and are more susceptible to LPS-induced septic shock which is further enhanced by blocking IL-10 signal. These results reveal a novel mechanism by which β-arrestin 2 negatively regulates TLR4-mediated inflammatory reactions

Recruited Metastasis Suppressor NM23-H2 Attenuates Expression and Activity of Peroxisome Proliferator-Activated Receptor δ (PPARδ) in Human Cholangiocarcinoma

Background: Peroxisome proliferator-activated receptor δ (PPARδ) is a versatile regulator of distinct biological processes and overexpression of PPARδ in cancer may be partially related to its suppression of its own co-regulators. Aims: To determine whether recruited suppressor proteins bind to and regulate PPARδ expression, activity and PPARδ-dependent cholangiocarcinoma proliferation. Methods: Yeast two-hybrid assays were done using murine PPARδ as bait. PPARδ mRNA expression was determined by qPCR. Protein expression was measured by western blot. Immunohistochemistry and fluorescence microscopy were used to determine PPARδ expression and co-localization with NDP Kinase alpha (NM23-H2). Cell proliferation assays were performed to determine cell numbers. Results: Yeast two-hybrid screening identified NM23-H2 as a PPARδ binding protein and their interaction was confirmed. Overexpressed PPARδ or treatment with the agonist GW501516 resulted in increased cell proliferation. NM23-H2 siRNA activated PPARδ luciferase promoter activity, upregulated PPARδ RNA and protein expression and increased GW501516-stimulated CCA growth. Overexpression of NM23-H2 inhibited PPARδ luciferase promoter activity, downregulated PPARδ expression and AKT phosphorylation and reduced GW501516-stimulated CCA growth. Conclusions: We report the novel association of NM23-H2 with PPARδ and the negative regulation of PPARδ expression by NM23-H2 binding to the C-terminal region of PPARδ. These findings provide evidence that the metastasis suppressor NM23-H2 is involved in the regulation of PPARδ-mediated proliferation

Liver X Receptor β and Peroxisome Proliferator-Activated Receptor δ Regulate Cholesterol Transport in Murine Cholangiocytes

Nuclear receptors (NRs) play crucial roles in the regulation of hepatic cholesterol synthesis, metabolism, and conversion to bile acids, but their actions in cholangiocytes have not been examined. In this study, we investigated the roles of NRs in cholangiocyte physiology and cholesterol metabolism and flux. We examined the expression of NRs and other genes involved in cholesterol homeostasis in freshly isolated and cultured murine cholangiocytes and found that these cells express a specific subset of NRs, including liver X receptor (LXR) β and peroxisome proliferator-activated receptor (PPAR) δ. Activation of LXRβ and/or PPARδ in cholangiocytes induces ATP-binding cassette cholesterol transporter A1 (ABCA1) and increases cholesterol export at the basolateral compartment in polarized cultured cholangiocytes. In addition, PPARδ induces Niemann-Pick C1-like L1 (NPC1L1), which imports cholesterol into cholangiocytes and is expressed on the apical cholangiocyte membrane via specific interaction with a peroxisome proliferator-activated response element (PPRE) within the NPC1L1 promoter. Conclusion: We propose that (1) LXRβ and PPARδ coordinate NPC1L1/ABCA1-dependent vectorial cholesterol flux from bile through cholangiocytes and (2) manipulation of these processes may influence bile composition with important applications in cholestatic liver disease and gallstone disease, two serious health concerns for humans