Human intestinal macrophages contribute to tissue homeostasis in noninflamed mucosa through profound down-regulation of pro-inflammatory cytokine release. Here, we show that this down-regulation extends to Toll-like receptor (TLR)-induced cytokine release, as intestinal macrophages expressed TLR3–TLR9 but did not release cytokines in response to TLR-specific ligands. Likely contributing to this unique functional profile, intestinal macrophages expressed markedly down-regulated adapter proteins MyD88 and Toll interleukin receptor 1 domain-containing adapter-inducing interferon β, which together mediate all TLR MyD88-dependent and -independent NF-κB signaling, did not phosphorylate NF-κB p65 or Smad-induced IκBα, and did not translocate NF-κB into the nucleus. Importantly, transforming growth factor-β released from intestinal extracellular matrix (stroma) induced identical down-regulation in the NF-κB signaling and function of blood monocytes, the exclusive source of intestinal macrophages. Our findings implicate stromal transforming growth factor-β-induced dysregulation of NF-κB proteins and Smad signaling in the differentiation of pro-inflammatory blood monocytes into noninflammatory intestinal macrophages.

Infection by viruses, including herpes simplex virus-1 (HSV-1), and cellular stresses cause widespread disruption of transcription termination (DoTT) of RNA polymerase II (RNAPII) in host genes. However, the underlying mechanisms remain unclear. Here, we demonstrate that the HSV-1 immediate early protein ICP27 induces DoTT by directly binding to the essential mRNA 3' processing factor CPSF. It thereby induces the assembly of a dead-end 3' processing complex, blocking mRNA 3' cleavage. Remarkably, ICP27 also acts as a sequencedependent activator of mRNA 3' processing for viral and a subset of host transcripts. Our results unravel a bimodal activity of ICP27 that plays a key role in HSV-1-induced host shutoff and identify CPSF as an important factor that mediates regulation of transcription termination. These findings have broad implications for understanding the regulation of transcription termination by other viruses, cellular stress and cancer.

Sorbitol and sucrose are major products of photosynthesis distributed in apple trees (Malus domestica Borkh. cv. ''Greensleeves'') that affect quality in fruit. Transgenic apple plants were silenced or up-regulated for sorbitol-6-phosphate dehydrogenase by using the CaMV35S promoter to define the role of sorbitol distribution in fruit development. Transgenic plants with suppressed sorbitol-6-phosphate dehydrogenase compensated by accumulating sucrose and starch in leaves, and morning and midday net carbon assimilation rates were significantly lower. The sorbitol to sucrose ratio in leaves was reduced by Ϸ90% and in phloem exudates by Ϸ75%. The fruit accumulated more glucose and less fructose, starch, and malic acid, with no overall differences in weight and firmness. Sorbitol dehydrogenase activity was reduced in silenced fruit, but activities of neutral invertase, vacuolar invertase, cell wall-bound invertase, fructose kinase, and hexokinase were unaffected. Analyses of transcript levels and activity of enzymes involved in carbohydrate metabolism throughout fruit development revealed significant differences in pathways related to sorbitol transport and breakdown. Together, these results suggest that sorbitol distribution plays a key role in fruit carbon metabolism and affects quality attributes such as sugar-acid balance and starch accumulation.gene silencing ͉ sugar-acid balance ͉ translocation ͉ starch accumulation A pples are in the family Rosaceae, which includes temperate species with fleshy fruit. The family produces sorbitol, sucrose, and starch as primary products of photosynthesis ( Fig. 1). Sorbitol is synthesized via reduction of glucose-6-phosphate to sorbitol-6-phosphate by aldose-6-phosphate reductase (EC 1.1.1.200), also called sorbitol-6-phosphate dehydrogenase (S6PDH). Sorbitol is the main sugar present in apple leaves and is transported in phloem with sucrose ( Fig. 1) (1). Sugars are distributed through a network of sieve elements to sink tissues such as developing fruit, seed, and leaves in a complex process regulated by photosynthetic rate, phloem loading, long-distance translocation and unloading, postphloem transport, and metabolism within sink tissues (2, 3). Transporters of sugar alcohols like sorbitol and other structural components involved in phloem unloading of sorbitol into the apoplast of apple fruit have been identified (4-6).In sink tissues such as fruit, sucrose is metabolized by invertases and sucrose synthase, whereas sorbitol is converted to fructose by sorbitol dehydrogenase (SDH, EC 1.1.1.14) (7,8). Expression of SDH in developing apple fruit is highest 2-3 weeks after bloom, a period sensitive to carbon availability (9). Additionally, sorbitol and other sugars may regulate expression of SDH mRNA and protein in pear fruit slices (10).In this article, we describe how sorbitol distribution affects fruit quality using transgenic apple plants with altered levels of S6PDH. Understanding the relationship between sorbitol accumulation and fruit quality is important not only for a...

HIV causes rapid CD4+ T cell depletion in the gut mucosa, resulting in immune deficiency and defects in the intestinal epithelial barrier. Breakdown in gut barrier integrity is linked to chronic inflammation and disease progression. However, the early effects of HIV on the gut epithelium, prior to the CD4+ T cell depletion, are not known. Further, the impact of early viral infection on mucosal responses to pathogenic and commensal microbes has not been investigated. We utilized the SIV model of AIDS to assess the earliest host-virus interactions and mechanisms of inflammation and dysfunction in the gut, prior to CD4+ T cell depletion. An intestinal loop model was used to interrogate the effects of SIV infection on gut mucosal immune sensing and response to pathogens and commensal bacteria in vivo. At 2.5 days post-SIV infection, low viral loads were detected in peripheral blood and gut mucosa without CD4+ T cell loss. However, immunohistological analysis revealed the disruption of the gut epithelium manifested by decreased expression and mislocalization of tight junction proteins. Correlating with epithelial disruption was a significant induction of IL-1β expression by Paneth cells, which were in close proximity to SIV-infected cells in the intestinal crypts. The IL-1β response preceded the induction of the antiviral interferon response. Despite the disruption of the gut epithelium, no aberrant responses to pathogenic or commensal bacteria were observed. In fact, inoculation of commensal Lactobacillus plantarum in intestinal loops led to rapid anti-inflammatory response and epithelial tight junction repair in SIV infected macaques. Thus, intestinal Paneth cells are the earliest responders to viral infection and induce gut inflammation through IL-1β signaling. Reversal of the IL-1β induced gut epithelial damage by Lactobacillus plantarum suggests synergistic host-commensal interactions during early viral infection and identify these mechanisms as potential targets for therapeutic intervention.

A series of nonnucleoside, N-␣-methylbenzyl-N-arylthiourea analogs were identified which demonstrated selective activity against varicella-zoster virus (VZV) but were inactive against other human herpesviruses, including herpes simplex virus. Representative compounds had potent activity against VZV early-passage clinical isolates and an acyclovir-resistant isolate. Resistant viruses generated against one inhibitor were also resistant to other compounds in the series, suggesting that this group of related small molecules was acting on the same virus-specific target. Sequencing of the VZV ORF54 gene from two independently derived resistant viruses revealed mutations in ORF54 compared to the parental VZV strain Ellen sequence. Recombinant VZV in which the wild-type ORF54 sequence was replaced with the ORF54 gene from either of the resistant viruses became resistant to the series of inhibitor compounds. Treatment of VZV-infected cells with the inhibitor impaired morphogenesis of capsids. Inhibitor-treated cells lacked DNA-containing dense-core capsids in the nucleus, and only incomplete virions were present on the cell surface. These data suggest that the VZV-specific thiourea inhibitor series block virus replication by interfering with the function of the ORF54 protein and/or other proteins that interact with the ORF54 protein.Varicella-zoster virus (VZV) causes a disseminated primary infection, chickenpox, and later may reactivate to cause herpes zoster, commonly known as shingles (3,26). Herpes zoster can result in pain lasting over 1 month from the onset of the rash, termed postherpetic neuralgia (PHN). PHN is often a debilitating condition that is quite difficult to treat (15,32,33).Acyclovir (ACV), valaciclovir, and famciclovir are the primary antivirals used for treating VZV infections in both immunocompetent and immunocompromised individuals (25). Unfortunately, despite these medications, PHN remains a major problem, and the currently available drugs have a limited effect on prevention of this condition. Thus, there is a need for additional, more effective medications to treat herpes zoster in adults.The development of antiviral resistance remains a concern, particularly when treatment relies on only a small number of approved drugs with common modes of action (13,14,25,26). ACV, valaciclovir (which is metabolized to acyclovir), and famciclovir (the prodrug of penciclovir) are all phosphorylated by the viral thymidine kinase as an initial step for intracellular activation. They are subsequently phosphorylated by cellular kinases, and the activated compounds inhibit the viral DNA polymerase. Sorivudine and brivudine are also potent inhibitors of VZV, and although they represent a different class of nucleoside analogues from ACV, they also require phosphorylation by the viral thymidine kinase for activation (18,31). While thymidine kinase-deficient VZV can be treated with foscarnet, a direct inhibitor of the viral DNA polymerase (25), this drug requires intravenous administration and has a marked potential for...