Depletion of host Langerhans cells before transplantation of donor alloreactive T cells prevents skin graft-versus-host disease

Skin is the most commonly affected organ in graft-versus-host disease (GVHD). To explore the role of Langerhans cells in GVHD, the principal dendritic cells of the skin, we studied the fate of these cells in mice transplanted with allogeneic bone marrow. In contrast to other dendritic cells, host Langerhans cells were replaced by donor Langerhans cells only when donor T cells were administered along with bone marrow, and the extent of Langerhans cell chimerism correlated with the dose of donor T cells injected. Donor T cells depleted host Langerhans cells through a Fas-dependent pathway and induced the production in skin of CCL20, which was required for the recruitment of donor Langerhans cells. Administration of donor T cells to bone marrow-chimeric mice with persistent host Langerhans cells, but not to mice whose Langerhans cells had been replaced, resulted in marked skin GVHD. These findings indicate a crucial role for donor T cells in host Langerhans cell replacement, and show that host dendritic cells can persist in nonlymphoid tissue for the duration of an animal's life and can trigger GVHD despite complete blood chimerism.     

c-Abl tyrosine kinase selectively regulates p73 nuclear matrix association

p73 is a structural and functional homologue of the p53 tumor-suppressor protein. Like p53, p73 is activated in response to DNA-damaging insults to induce cell cycle arrest or apoptosis. Under these conditions p73 is tyrosine-phosphorylated by c-Abl, a prerequisite modification for p73 to elicit cell death in fibroblasts. In this study we report that in response to ionizing radiation, p73 undergoes nuclear redistribution and becomes associated with the nuclear matrix. This association is c-Abl-dependent because it was not observed in cells that are defective in c-Abl kinase activation. Moreover, STI-571, a specific c-Abl kinase inhibitor, is sufficient to block significantly p73 alpha nuclear matrix association. The observed c-Abl dependence of nuclear matrix association was recapitulated in the heterologous baculovirus system. Under these conditions p73 alpha but not p53 is specifically tyrosine-phosphorylated by c-Abl. Moreover, the phosphorylated p73 alpha is predominantly found in association with the nuclear matrix. Thus, in response to ionizing radiation p73 is modified in a c-Abl-dependent manner and undergoes nuclear redistribution and translocates to associate with the nuclear matrix. Our data describe a novel mechanism of p73 regulation.     

Aggression and violence: perspectives on integrating animal and human research approaches

Aggression and violence are concerns that engage us across society as moral and cultural issues. They are also critical issues for mental health research--both for survivors and for understanding how such behaviors occur. Interpersonal violence often explodes in deliberate acts of physical force leaving survivors behind with a diminished sense of control that is often shadowed by persistent fear and anxiety. The treatment of the victims is a clear and immediate concern; from their perspectives the medical consequences require effective attention whether they suffered as a result of acts of nature, mental disease, ideology, or combinations of these. At the same time preventing violent behavior from happening in the first place is a compelling challenge for public health research.     

Stimulation of enveloped virus infection by beta-amyloid fibrils

Alzheimer's disease is characterized by deposition of beta-amyloid peptide (Abeta) into plaques in the brain, leading to neuronal toxicity and dementia. Human immunodeficiency virus type 1 (HIV-1) infection of the central nervous system can also cause a dementia, and amyloid deposition in the central nervous system is significantly higher in HIV-1-infected individuals compared with uninfected controls. Here we report that Abeta fibrils stimulated, by 5-20-fold, infection of target cells expressing CD4 and an appropriate coreceptor by multiple HIV-1 isolates but did not permit infection of cells lacking these receptors. Abeta enhanced infection at the stage of virus attachment or entry into the cell. Abeta fibrils also stimulated infection by amphotrophic Moloney leukemia virus, herpes simplex virus, and viruses pseudotyped with the envelope glycoprotein of vesicular stomatitis virus. Other synthetic fibril-forming peptides similarly enhanced viral infection and may be useful in gene delivery applications utilizing retroviral vectors. These data suggest that Abeta deposition may increase the vulnerability of the central nervous system to enveloped viral infection and that amyloidogenic peptides could be useful in enhancing gene transfer by enveloped viral vectors.     

Evolution of duplicated alpha-tubulin genes in ciliates

Ciliates provide a powerful system to analyze the evolution of duplicated alpha-tubulin genes in the context of single-celled organisms. Genealogical analyses of ciliate alpha-tubulin sequences reveal five apparently recent gene duplications. Comparisons of paralogs in different ciliates implicate differing patterns of substitutions (e.g., ratios of replacement/synonymous nucleotides and radical/conservative amino acids) following duplication. Most substitutions between paralogs in Euplotes crassus, Halteria grandinella and Paramecium tetraurelia are synonymous. In contrast, alpha-tubulin paralogs within Stylonychia lemnae and Chilodonella uncinata are evolving at significantly different rates and have higher ratios of both replacement substitutions to synonymous substitutions and radical amino acid changes to conservative amino acid changes. Moreover, the amino acid substitutions in C. uncinata and S. lemnae paralogs are limited to short stretches that correspond to functionally important regions of the alpha-tubulin protein. The topology of ciliate alpha-tubulin genealogies are inconsistent with taxonomy based on morphology and other molecular markers, which may be due to taxonomic sampling, gene conversion, unequal rates of evolution, or asymmetric patterns of gene duplication and loss.     

IL-13-induced chemokine responses in the lung: role of CCR2 in the pathogenesis of IL-13-induced inflammation and remodeling

IL-13 stimulates inflammatory and remodeling responses and contributes to the pathogenesis of human airways disorders. To further understand the cellular and molecular events that mediate these responses, we characterized the effects of IL-13 on monocyte chemotactic proteins (MCPs) and compared the tissue effects of transgenic IL-13 in mice with wild-type (+/+) and null (-/-) CCR2 loci. Transgenic IL-13 was a potent stimulator of MCP-1, -2, -3, and -5. This stimulation was not specific for MCPs because macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta, MIP-2, MIP-3alpha, thymus- and activation-regulated chemokine, thymus-expressed chemokine, eotaxin, eotaxin 2, macrophage-derived chemokines, and C10 were also induced. The ability of IL-13 to increase lung size, alveolar size, and lung compliance, to stimulate pulmonary inflammation, hyaluronic acid accumulation, and tissue fibrosis, and to cause respiratory failure and death were markedly decreased, whereas mucus metaplasia was not altered in CCR2(-/-) mice. CCR2 deficiency did not decrease the basal or IL-13-stimulated expression of target matrix metalloproteinases or cathepsins but did increase the levels of mRNA encoding alpha1-antitrypsin, tissue inhibitor of metalloproteinase-1, -2, and -4, and secretory leukocyte proteinase inhibitor. In addition, the levels of bioactive and total TGF-beta(1) were decreased in lavage fluids from IL-13 transgenic mice with -/- CCR2 loci. These studies demonstrate that IL-13 is a potent stimulator of MCPs and other CC chemokines and document the importance of MCP-CCR2 signaling in the pathogenesis of the IL-13-induced pulmonary phenotype.     

Button osteoma: its etiology and pathophysiology

The present study investigates a circumscribed bony overgrowth on the cranial vault, known as button osteoma (BtO) and referred to here as button lesion (BtL). We discuss its anthropological implications. Data on its histology, location, and population distribution (by age, race, and gender) are provided. Microscopically, BtL is composed of well-organized dense lamellated bone which is poorly vascularized and with very few osteocytes. It forms a dome-shaped roof over an underlying diploeized area which includes the ectocranial table. The frequency of BtL is similar in modern (37.6%) and archaeological (41.1%) populations, in blacks, whites, males, and females, and correlates with age. It is rare in nonhuman primates. Fifty-five percent of the human skulls studied by us had BtL only on the parietal, 23.6% on the frontal, and 3.6% on the occipital bones. Fifteen percent had BtL on both the frontal and parietal bones. No lateral preference was found. Most skulls with BtL (64.1%) had only one lesion, 20.4% had two BtL, and 15.4% demonstrated multiple BtL. The average number of button osteomas on an affected skull was 1.97. The frequency of large osteomas (0.5-1.0 cm) was similar in young and old age groups. The demographic characteristics of BtL, mainly its high frequency among ancient and modern populations, its independence of sex and race, its scarcity in other primates, and the fact that its macro- and microstruture are indicative of an hamartoma (and not an osteoma or exostosis) suggest an evolutionary background to the phenomenon.     

Genotoxic evaluation of the organophosphorous pesticide temephos

The chemical compound temephos (0,0,0',0'-tetrametyl-0,0'-thiodi-p-phenylene phosphorothioate) is an organophosphorous pesticide that has been used in Brazil since 1967 in control campaigns against the mosquito Aedes aegypti, the vector of dengue and yellow fever. We used single cell gel electrophoresis (SCGE), SOS/umu and Ames/Salmonella assays to test the toxicity and mutagenicity of temephos. Temephos was genotoxic in the SCGE assay, inducing severe DNA lesions (type IV lesions) at doses above 1.34 micro M. It was mutagenic, but not toxic, in the SOS/umu assay to Escherichia coli strain PQ37, but not to PQ35, at concentrations above 1.33 micro M, particularly when the S9 mixture was not used in the assay. Temephos was not mutagenic in the Ames assay with S. typhimurium strains TA97, TA98, TA100 and TA102, both with and without metabolic activation. However, temephos at concentrations above 3.33 micro M was mutagenic to TA98NR, YG7104 and YG7108, both with and without metabolic activation. In conclusion, temephos was genotoxic and mutagenic in all the three tests used, and in two of them at concentrations similar to those routinely used to combat Aedes aegypti.     

Interactions of human secretin with sterically stabilized phospholipid micelles amplify peptide-induced vasodilation in vivo

Secretin, a 27-amino acid neuropeptide, is a member of the glucagon/secretin/vasoactive intestinal polypeptide (VIP) superfamily of amphipathic peptides that elicits transient vasodilation in vivo. The purpose of this study was to determine whether association of human secretin with sterically stabilized phospholipid micelles (SSM) amplifies the vasorelaxant effects of the peptide in the peripheral microcirculation in vivo. We found that secretin in saline evoked significant concentration-dependent vasodilation in the intact hamster cheek pouch microcirculation (P < 0.05). This response was potentiated and prolonged significantly when secretin was associated with SSM (P < 0.05). Vasodilation evoked by secretin in saline and secretin in SSM was abrogated by VIP(10-28), a VIP receptor antagonist, but not by PACAP(6-38), a PACAP receptor antagonist, or Hoe140, a selective bradykinin B(2) receptor antagonist. Collectively, these data indicate that self-association of human secretin with SSM significantly amplifies peptide vasoreactivity in the intact peripheral microcirculation through activation of VIP receptors. We suggest that the vasoactive effects of human secretin in vivo are, in part, phospholipid-dependent.     

Structure-activity relationships of heparin-mimicking compounds in induction of bFGF release from extracellular matrix and inhibition of smooth muscle cell proliferation and heparanase activity

A series of nine synthetic polyaromatic compounds were synthesized by polymerization of aromatic ring monomers with formaldehyde, which yield substantially ordered backbones with different functional anionic groups (hydroxyl and carboxyl) on the phenol ring. These compounds were tested for their heparin-mimicking activity: (1) inhibition of heparanase activity; (2) inhibition of SMC proliferation; and (3) release of bFGF from the ECM. We demonstrate that compounds that have two hydroxyl groups para and ortho to the carboxylic group and a carboxylic group at a distance of two carbons from the phenol ring inhibit heparanase activity and SMC proliferation, as well as induced an almost complete release of bFGF from ECM. Addition of a methyl group next to the carboxylic group led to a preferential inhibition of heparanase activity. Similar results were obtained with a compound that contains one hydroxyl group para to the carboxylic group and an ether group near the carboxylic group on the phenol ring. Preferential inhibition of SMC proliferation was best achieved when the position of the hydroxyl group is para and ortho to the carboxylic group and the carboxylic group is at a distance of one carbon from the phenol ring. On the other hand, for maximal release of bFGF from ECM, the position of the carboxylic group should be three carbons away from the phenol ring. These new heparin-mimicking compounds may have a potential use in inhibition of tumor metastasis, arteriosclerosis, and inflammation.