The Regulation of Intestinal Mucosal Barrier by Myosin Light Chain Kinase/Rho Kinases

The intestinal epithelial apical junctional complex, which includes tight and adherens junctions, contributes to the intestinal barrier function via their role in regulating paracellular permeability. Myosin light chain II (MLC-2), has been shown to be a critical regulatory protein in altering paracellular permeability during gastrointestinal disorders. Previous studies have demonstrated that phosphorylation of MLC-2 is a biochemical marker for perijunctional actomyosin ring contraction, which increases paracellular permeability by regulating the apical junctional complex. The phosphorylation of MLC-2 is dominantly regulated by myosin light chain kinase- (MLCK-) and Rho-associated coiled-coil containing protein kinase- (ROCK-) mediated pathways. In this review, we aim to summarize the current state of knowledge regarding the role of MLCK- and ROCK-mediated pathways in the regulation of the intestinal barrier during normal homeostasis and digestive diseases. Additionally, we will also suggest potential therapeutic targeting of MLCK- and ROCK-associated pathways in gastrointestinal disorders that compromise the intestinal barrier

Characterization of Bovine Intraepithelial T Lymphocytes in the Gut

Intraepithelial T lymphocytes (T-IELs), which constitute over 50% of the total T lymphocytes in the animal, patrol the mucosal epithelial lining to defend against pathogen invasion while maintaining gut homeostasis. In addition to expressing T cell markers such as CD4 and CD8, T-IELs display T cell receptors (TCR), including either TCRαβ or TCRγδ. Both humans and mice share similar T-IEL subsets: TCRγδ+, TCRαβ+CD8αα+, TCRαβ+CD4+, and TCRαβ+CD8αβ+. Among these subsets, human T-IELs are predominantly TCRαβ+ (over 80%), whereas those in mice are mostly TCRγδ+ (~60%). Of note, the majority of the TCRγδ+ subset expresses CD8αα in both species. Although T-IELs have been extensively studied in humans and mice, their profiles in cattle have not been well examined. Our study is the first to characterize bovine T-IELs using flow cytometry, where we identified several distinct features. The percentage of TCRγδ+ was comparable to that of TCRαβ+ T-IELs (both ~50% of CD3+), and the majority of bovine TCRγδ+ T-IELs did not express CD8 (CD8−) (above 60%). Furthermore, about 20% of TCRαβ+ T-IELs were CD4+CD8αβ+, and the remaining TCRαβ+ T-IELs were evenly distributed between CD4+ and CD8αβ+ (~40% of TCRαβ+ T-IELs each) with no TCRαβ+CD8αα+ identified. Despite these unique properties, bovine T-IELs, similar to those in humans and mice, expressed a high level of CD69, an activation and tissue-retention marker, and a low level of CD62L, a lymphoid adhesion marker. Moreover, bovine T-IELs produced low levels of inflammatory cytokines such as IFNγ and IL17A, and secreted small amounts of the immune regulatory cytokine TGFβ1. Hence, bovine T-IELs’ composition largely differs from that of human and mouse, with the dominance of the CD8− population among TCRγδ+ T-IELs, the substantial presence of TCRαβ+CD4+CD8αβ+ cells, and the absence of TCRαβ+CD8αα+ T-IELs. These results provide the groundwork for conducting future studies to examine how bovine T-IELs respond to intestinal pathogens and maintain the integrity of the gut epithelial barrier in animals

Schedule-dependent synergistic effect of rituximab on methotrexate chemotherapy against lymphoma of the central nervous system

We hypothesized that methotrexate (MTX) normalizes the increased permeability of the blood-tumor barrier and thus reduces the accessibility of rituximab (RTX) to central nervous system (CNS) lymphoma. Here, we evaluated the combinational treatment capability of RTX and MTX using an alternative treatment schedule against CNS lymphoma. We developed a CNS lymphoma animal model that closely mimics the morphological and molecular characteristics of human CNS lymphoma by injecting Raji human Burkitt lymphoma cells into the brains of immune-compromised mice and tested a novel combinational treatment schedule by which penetration of RTX was not influenced by MTX administration. RTX was conjugated with Alexa Fluor 680, and its distribution in the brain was analyzed by in vivo imaging. When MTX treatment was followed by a 3-day post RTX administration, RTX was scarcely distributed in the brain, and there were only modest statistically insignificant therapeutic effects compared with the control mice which received sham injections. In contrast, RTX administration followed by a 3-day post MTX treatment showed significantly increased distribution of RTX and significantly reduced tumor volume in the brain. Collectively, our data demonstrate that RTX can be successfully combined with MTX using an alternative treatment schedule that allows increased distribution of RTX in CNS lymphoma.Jahnke K, 2009, NEURO-ONCOLOGY, V11, P503, DOI 10.1215/15228517-2008-119WANG W, 2006, NEUROSURG FOCUS, V21, pE14Herrlinger U, 2005, ANN NEUROL, V57, P843Enting RH, 2004, NEUROLOGY, V63, P901Wong ET, 2004, CANCER, V101, P139, DOI 10.1002/cncr.20339Neuwelt EA, 2004, NEUROSURGERY, V54, P131, DOI 10.1227/01.NEU.0000097715.11966.8EDeAngelis LM, 2002, J CLIN ONCOL, V20, P4643, DOI 10.1200/JCO.2002.11.013Abrey LE, 2000, J CLIN ONCOL, V18, P3144McLaughlin P, 1998, J CLIN ONCOL, V16, P2825Neuwelt EA, 1998, CLIN CANCER RES, V4, P1549Maloney DG, 1997, J CLIN ONCOL, V15, P3266BARNETT PA, 1995, AM J PATHOL, V146, P436NEUWELT EA, 1994, J NUCL MED, V35, P1831