Evidence for an early role for BMP4 signaling in thymus and parathyroid morphogenesis

The thymus and parathyroids are pharyngeal endoderm-derived organs that develop from common organ primordia, which undergo a series of morphological events resulting in separate organs in distinct locations in the embryo. Previous gene expression and functional analyses have suggested a role for BMP4 signaling in early thymus organogenesis. We have used conditional deletion of Bmp4 or Alk3 from the pharyngeal endoderm and/or the surrounding mesenchyme using Foxg1-Cre, Wnt1-Cre or Foxn1-Cre. Deleting Bmp4 from both neural crest cells (NCC) and early endoderm-derived epithelial cells in Foxg1-Cre;Bmp4 conditional mutants resulted in defects in thymus-parathyroid morphogenesis. Defects included reduced condensation of mesenchymal cells around the epithelium, partial absence of the thymic capsule, a delay in thymus and parathyroid separation, and failed or dramatically reduced organ migration. Patterning of the primordia and initial organ differentiation were not affected in any of the mutants. Deleting Bmp4 from NCC-derived mesenchyme or differentiating thymic epithelial cells (TECs) had no effects on thymus-parathyroid development, while loss of Alk3 from either neural crest cells or TECs resulted in only a mild thymic hypoplasia. these results show that the processes of cell specification and morphogenesis during thymus-parathyroid development are independently controlled, and suggest a specific temporal and spatial role for BMP4-mediated epithelial-mesenchymal interactions during early thymus and parathyroid morphogenesis.     

Central Region of Talin Has a Unique Fold That Binds Vinculin and Actin

Talin is an adaptor protein that couples integrins to F-actin. Structural studies show that the N-terminal talin head contains an atypical FERM domain, whereas the N- and C-terminal parts of the talin rod include a series of α-helical bundles. However, determining the structure of the central part of the rod has proved problematic. Residues 1359–1659 are homologous to the MESDc1 gene product, and we therefore expressed this region of talin in Escherichia coli. The crystal structure shows a unique fold comprised of a 5- and 4-helix bundle. The 5-helix bundle is composed of nonsequential helices due to insertion of the 4-helix bundle into the loop at the C terminus of helix α3. The linker connecting the bundles forms a two-stranded anti-parallel β-sheet likely limiting the relative movement of the two bundles. Because the 5-helix bundle contains the N and C termini of this module, we propose that it is linked by short loops to adjacent bundles, whereas the 4-helix bundle protrudes from the rod. This suggests the 4-helix bundle has a unique role, and its pI (7.8) is higher than other rod domains. Both helical bundles contain vinculin-binding sites but that in the isolated 5-helix bundle is cryptic, whereas that in the isolated 4-helix bundle is constitutively active. In contrast, both bundles are required for actin binding. Finally, we show that the MESDc1 protein, which is predicted to have a similar fold, is a novel actin-binding protein.     

Innate immune response to human bone marrow fibroblastic cell implantation in CB17 scid/beige mice

Immunocompromised mouse models have been extensively used to assess human cell implantation for evaluation of cytotherapy, gene therapy and tissue engineering strategies, as these mice are deficient in T and B lymphoid cells. However, the innate immune response and its effect on human cell xenotransplantation in these mouse models are mainly unknown. The aim of this study is to characterise the myeloid populations in the spleen and blood of CB17 scid beige (CB17 sb) mice, and to study the inflammatory cell responses to xenogeneic implantation of enhanced green fluorescent protein (GFP)-labelled human bone marrow fibroblastic (HBMF) cells into CB17 sb mice. The results indicate that even though CB17 sb mice are deficient in B- and T-cells, they exhibit some increases in their monocyte (Mo), macrophage (Mphi) and neutrophil (Neu) populations. NK cell and eosinophil populations show no differences compared with wild-type Balb/C mice. An innate immune response, identified by CR3 (CD11b/CD18)-positive myeloid inflammatory cells and F4/80-positive macrophages, was evident in the tissues where HBMF cells were implanted. As a consequence, the majority of implanted HBMF cells were eliminated by 4 weeks after implantation. Interestingly, the mineralised matrix formed by osteogenic HBMF cells was also eroded by multinuclear Mphi-like giant cells. We conclude that CB17 sb mice retain active innate immune cells, which respond to HBMF cell xenotransplantation. This study highlights the importance of the innate immune cells in the anti-xenograft response and suggests that strategies to block the activities of these cells may ameliorate the progressive long-term elimination of xenotransplants.     

Malignant fibrous histiocytoma of the glans penis: a case report

BACKGROUND: Malignant fibrous histiocytoma has been regarded as the most common sarcoma of older adults. However, recent opinion regards pleomorphic malignant fibrous histiocytoma as an undifferentiated high grade pleomorphic sarcoma not otherwise classifiable utilizing current techniques available in surgical pathology. Notwithstanding controversy regarding its nomenclature, malignant fibrous histiocytoma involving the penis is exceedingly rare, with only 4 cases previously described, to our knowledge. CASE: An uncircumcised 73-year-old male presented with a painless, granular, partially necrotic lesion beneath the penile foreskin. There was no history of sexually transmitted disease, constitutional symptoms or dysuria. Examination of penile shaft, testicles, spermatic cord and inguinal lymph nodes were unremarkable. Biopsy revealed a markedly pleomorphic sarcoma. Subsequent, partial penectomy revealed the same lesion with an adjacent area of squamous cell carcinoma in situ. CONCLUSION: Malignant fibrous histiocytoma remains a diagnosis of exclusion. The investigation requires extensive tumor sampling in search of areas of differentiation and a complete battery of immunohistochemical markers. Therapeutically important entities in the differential diagnosis that must be ruled out include other poorly differentiated sarcomas, sarcomatoid squamous cell carcinoma and desmoplastic melanoma.     

Celastrus paniculatus seed oil and organic extracts attenuate hydrogen peroxide- and glutamate-induced injury in embryonic rat forebrain neuronal cells

Seed oil of Celastrus paniculatus Willd. (CP) has been reported to improve memory and the methanolic extract (ME) of CP was shown to exhibit free-radical-scavenging properties and anti-oxidant effects in human non-immortalized fibroblasts. In the present study, we have investigated the free-radical-scavenging capacity of CP seed oil (CPO) and two extracts, an ethanolic extract (EE) and a ME. CPO and EE showed dose-dependent, free-radical-scavenging capacity, but to a lesser degree than observed for ME. Oxidative stress involves the generation of free radicals and free radical scavenging is one of the mechanisms of neuroprotection. We therefore investigated the effects of CPO, ME, and EE for protection against hydrogen peroxide (H(2)O(2))- and glutamate-induced neurotoxicity in embryonic rat forebrain neuronal cells (FBNC). Pre-treatment of neuronal cells with CPO dose-dependently attenuated H(2)O(2)-induced neuronal death. Pre-treatment with ME and EE partially attenuated H(2)O(2)-induced toxicity, but these extracts were less effective than CPO for neuronal survival. In H(2)O(2)-treated cells, cellular superoxide dismutase (SOD) activity was unaffected, but catalase activity was decreased and levels of malondialdehyde (MDA) were increased. Pre-treatment with CPO, ME, or EE increased catalase activity and decreased MDA levels significantly. Also, CPO pre-treatment attenuated glutamate-induced neuronal death dose-dependently. The activity of cellular acetylcholinesterase (AChE) was not affected by CPO, ME, or EE, suggesting that the neuroprotection offered by CPO was independent of changes in AChE activity. Taken together, the data suggest that CPO, ME, and EE protected neuronal cells against H(2)O(2)-induced toxicity in part by virtue of their antioxidant properties, and their ability to induce antioxidant enzymes. However, CPO, which exhibited the least antioxidant properties, was the most effective in preventing neuronal cells against H(2)O(2)- and glutamate-induced toxicities. Thus, in addition to free-radical scavenging attributes, the mechanism of CP seed component (CP-C) neuroprotection must be elucidated.     

Restricted epithelial proliferation by lacritin via PKCalpha-dependent NFAT and mTOR pathways

Renewal of nongermative epithelia is poorly understood. The novel mitogen "lacritin" is apically secreted by several nongermative epithelia. We tested 17 different cell types and discovered that lacritin is preferentially mitogenic or prosecretory for those types that normally contact lacritin during its glandular outward flow. Mitogenesis is dependent on lacritin's C-terminal domain, which can form an alpha-helix with a hydrophobic face, as per VEGF's and PTHLP's respective dimerization or receptor-binding domain. Lacritin targets downstream NFATC1 and mTOR. The use of inhibitors or siRNA suggests that lacritin mitogenic signaling involves Galpha(i) or Galpha(o)-PKCalpha-PLC-Ca2+-calcineurin-NFATC1 and Galpha(i) or Galpha(o)-PKCalpha-PLC-phospholipase D (PLD)-mTOR in a bell-shaped, dose-dependent manner requiring the Ca2+ sensor STIM1, but not TRPC1. This pathway suggests the placement of transiently dephosphorylated and perinuclear Golgi-translocated PKCalpha upstream of both Ca2+ mobilization and PLD activation in a complex with PLCgamma2. Outward flow of lacritin from secretory cells through ducts may generate a proliferative/secretory field as a different unit of cellular renewal in nongermative epithelia where luminal structures predominate.     

Ovarian cancer cells polarize macrophages toward a tumor-associated phenotype

Tumor-associated macrophages (TAM) may have tumor-promoting activity, but it is not clear how their phenotype is achieved. In this study, we demonstrate that ovarian cancer cells switch cocultured macrophages to a phenotype similar to that found in ovarian tumors. Tumor cells caused dynamic changes in macrophage cytokine, chemokine, and matrix metalloprotease mRNA, and protein-inducing mediators that are found in human cancer. Macrophage mannose, mannose receptor, and scavenger receptors (SR-As) were also up-regulated by coculture, but not by conditioned medium. To further validate the model, we studied SR-A regulation on TAM in vitro and in vivo. Coculture of murine macrophages from mice deficient in TNF-alpha or its receptors revealed that TNF-alpha was key to SR-A induction via its p75 receptor. SR-A expression was also reduced in TAM from ovarian cancers treated with anti-TNF-alpha Abs or grown in TNF-alpha(-/-) mice. Chemical communication between tumor cells and macrophages may be important in regulating the cancer cytokine microenvironment.     

Costimulation via CD55 on human CD4+ T cells mediated by CD97

Decay-accelerating factor (CD55) is a complement regulatory protein, which is expressed by most cells to protect them from complement-mediated attack. CD55 also binds CD97, an EGF-TM7 receptor constitutively expressed on granulocytes and monocytes and rapidly up-regulated on T and B cells upon activation. Early results suggested that CD55 could further enhance T cell proliferation induced by phorbol ester treatment. The present study demonstrates that coengagement of CD55, using either cross-linking mAbs or its natural ligand CD97, and CD3 results in enhanced proliferation of human peripheral blood CD4(+) T cells, expression of the activation markers CD69 and CD25, and secretion of IL-10 and GM-CSF. Recently, an increase in T cell responsiveness in CD55(-/-) mice was shown to be mediated by a lack of complement regulation. In this study, we show that direct stimulation of CD55 on CD4(+) T cells with CD97 can modulate T cell activation but does not interfere with CD55-mediated complement regulation. Our results support a multifaceted role for CD55 in human T cell activation, constituting a further link between innate and adaptive immunity.     

Plasmacytoid dendritic cells do not migrate in intestinal or hepatic lymph

Plasmacytoid dendritic cells (pDCs) recognize pathogen-associated molecules, particularly viral, and represent an important mechanism in innate defense. They may however, also have roles in steady-state tolerogenic responses at mucosal sites. pDCs can be isolated from blood, mucosa, and lymph nodes (LNs). Although pDCs can express peripherally derived Ags in LNs and at mucosal sites, it is not clear whether pDCs actually migrate from the periphery in lymph or whether LN pDCs acquire Ags by other mechanisms. To determine whether pDCs migrate in lymph, intestine or liver-draining LNs were removed and thoracic duct leukocytes (TDLs) were collected. TDLs expressing MHC-II and CD45R, but not TCRalphabeta or CD45RA, were then analyzed. These enriched TDLs neither transcribe type I IFNs nor secrete inflammatory cytokines in response to viral stimuli in vitro or after a TLR7/8 stimulus in vivo. In addition, these TDLs do not express CD5, CD90, CD200, or Siglec-H, but do express Ig, and therefore represent B cells, despite their lack of CD45RA expression. Intestinal and hepatic lymph are hence devoid of bona fide pDCs under both steady-state conditions and after TLR7/8 stimulation. This shows that any role for pDCs in Ag-specific T cell activation or tolerance must differ from the roles of classical dendritic cells, because it cannot result from peripheral Ag capture, followed by migration of pDCs via lymph to the LN.