昭和20年代, 教室の日常と研究余話(第922回千葉医学会例会・第13回千葉精神科集談会)

<p>Unique MAA Arcs and Mechanistic Genes in Tight Junction Pathway.</p

Role of SPI-1 Secreted Effectors in Acute Bovine Response to Salmonella enterica Serovar Typhimurium: A Systems Biology Analysis Approach

Salmonella enterica Serovar Typhimurium (S. Typhimurium) causes enterocolitis with diarrhea and polymorphonuclear cell (PMN) influx into the intestinal mucosa in humans and calves. The Salmonella Type III Secretion System (T3SS) encoded at Pathogenicity Island I translocates Salmonella effector proteins SipA, SopA, SopB, SopD, and SopE2 into epithelial cells and is required for induction of diarrhea. These effector proteins act together to induce intestinal fluid secretion and transcription of C-X-C chemokines, recruiting PMNs to the infection site. While individual molecular interactions of the effectors with cultured host cells have been characterized, their combined role in intestinal fluid secretion and inflammation is less understood. We hypothesized that comparison of the bovine intestinal mucosal response to wild type Salmonella and a SipA, SopABDE2 effector mutant relative to uninfected bovine ileum would reveal heretofore unidentified diarrhea-associated host cellular pathways. To determine the coordinated effects of these virulence factors, a bovine ligated ileal loop model was used to measure responses to wild type S. Typhimurium (WT) and a ΔsipA, sopABDE2 mutant (MUT) across 12 hours of infection using a bovine microarray. Data were analyzed using standard microarray analysis and a dynamic Bayesian network modeling approach (DBN). Both analytical methods confirmed increased expression of immune response genes to Salmonella infection and novel gene expression. Gene expression changes mapped to 219 molecular interaction pathways and 1620 gene ontology groups. Bayesian network modeling identified effects of infection on several interrelated signaling pathways including MAPK, Phosphatidylinositol, mTOR, Calcium, Toll-like Receptor, CCR3, Wnt, TGF-β, and Regulation of Actin Cytoskeleton and Apoptosis that were used to model of host-pathogen interactions. Comparison of WT and MUT demonstrated significantly different patterns of host response at early time points of infection (15 minutes, 30 minutes and one hour) within phosphatidylinositol, CCR3, Wnt, and TGF-β signaling pathways and the regulation of actin cytoskeleton pathway

Systems Analysis of Early Host Gene Expression Provides Clues for Transient <i>Mycobacterium avium</i> ssp <i>avium</i> vs. Persistent <i>Mycobacterium avium</i> ssp <i>paratuberculosis</i> Intestinal Infections

<div><p>It has long been a quest in ruminants to understand how two very similar mycobacterial species, <i>Mycobacterium avium</i> ssp. p<i>aratuberculosis</i> (MAP) and <i>Mycobacterium avium</i> ssp. <i>avium</i> (MAA) lead to either a chronic persistent infection or a rapid-transient infection, respectively. Here, we hypothesized that when the host immune response is activated by MAP or MAA, the outcome of the infection depends on the early activation of signaling molecules and host temporal gene expression. To test our hypothesis, ligated jejuno-ileal loops including Peyer’s patches in neonatal calves were inoculated with PBS, MAP, or MAA. A temporal analysis of the host transcriptome profile was conducted at several times post-infection (0.5, 1, 2, 4, 8 and 12 hours). When comparing the transcriptional responses of calves infected with the MAA versus MAP, discordant patterns of mucosal expression were clearly evident, and the numbers of unique transcripts altered were moderately less for MAA-infected tissue than were mucosal tissues infected with the MAP. To interpret these complex data, changes in the gene expression were further analyzed by dynamic Bayesian analysis. Bayesian network modeling identified mechanistic genes, gene-to-gene relationships, pathways and Gene Ontologies (GO) biological processes that are involved in specific cell activation during infection. MAP and MAA had significant different pathway perturbation at 0.5 and 12 hours post inoculation. Inverse processes were observed between MAP and MAA response for epithelial cell proliferation, negative regulation of chemotaxis, cell-cell adhesion mediated by integrin and regulation of cytokine-mediated signaling. MAP inoculated tissue had significantly lower expression of phagocytosis receptors such as mannose receptor and complement receptors. This study reveals that perturbation of genes and cellular pathways during MAP infection resulted in host evasion by mucosal membrane barrier weakening to access entry in the ileum, inhibition of Ca signaling associated with decreased phagosome-lysosome fusion as well as phagocytosis inhibition, bias toward Th2 cell immune response accompanied by cell recruitment, cell proliferation and cell differentiation; leading to persistent infection. Contrarily, MAA infection was related to cellular responses associated with activation of molecular pathways that release chemicals and cytokines involved with containment of infection and a strong bias toward Th1 immune response, resulting in a transient infection.</p></div

Interleukin Gene Score Heat Map by Time Point Post Inoculation.

<p>The heat map shows a number of both up-regulated and down-regulated genes (15–240 minutes post-inoculation). The heat map shows that much of the up-regulation is short-lived for many of these genes and reversed expression direction or minimally expressed in later time points. Red indicates an activated state while green indicates repression and grey is no expression change from control.</p

Heatmap of Significantly Perturbed Pathways Scores in Bovine Peyer's Patch Infected with <i>B. melitensis</i>.

<p>Thirty-seven pathways were identified as significantly perturbed (97.5% confidence) from the early stage of infection (15–60 m.p.i.). The darker red gradients indicate higher Bayesian activation scores (more up-regulated gene expression within the pathway) while the darker green gradients indicate more repressed pathway activity (more down-regulated gene expression).</p

Pathway Score Heat Map for Cell Communication Related Pathways.

<p>This heat map shows the repressed state of activity for the Tight Junction (TJ) and Trefoil Factors (TF) pathway in comparison to the Gap Junction, Integrin-mediated Cell Adhesion and Cell Adhesion Molecules pathways. Note that the TJ and TF pathways have a complex activation pattern. The TJ is tri-phasic in that it is highly repressed in the early stage, becomes moderately activated at 60 and 120 min p.i, and then becomes repressed at 240 min p.i. The TF pathway is bi-phasic in that it is highly repressed in the early stage but becomes moderately activated at 120 and 240 min p.i. The darker red gradients indicate higher Bayesian activation scores (more up-regulated gene expression within the pathway) while the darker green gradients indicate more repressed pathway activity (more down-regulated gene expression).</p