Paracoccidioides brasiliensis Interferes on Dendritic Cells Maturation by Inhibiting PGE2 Production

Paracoccidioidomycosis (PCM) is a systemic mycosis, endemic in most Latin American countries, especially in Brazil, whose etiologic agent is the thermodimorphic fungus of the genus Paracoccidioides, comprising cryptic species of Paracoccidioides brasiliensis, S1, PS2, PS3 and Paracoccidioides lutzii. The mechanisms involved in the initial interaction of the fungus with cells of the innate immune response, as dendritic cells (DCs), deserve to be studied. Prostaglandins (PGs) are eicosanoids that play an important role in modulating functions of immune cells including DCs. Here we found that human immature DCs derived from the differentiation of monocytes cultured with GM-CSF and IL-4 release substantial concentrations of PGE₂, which, however, were significantly inhibited after challenge with P. brasiliensis. In vitro blocking of pattern recognition receptors (PRRs) by monoclonal antibodies showed the involvement of mannose receptor (MR) in PGE₂ inhibition by the fungus. In addition, phenotyping assays showed that after challenge with the fungus, DCs do not change their phenotype of immature cells to mature ones, as well as do not produce IL-12 p70 or adequate concentrations of TNF-α. Assays using exogenous PGE₂ confirmed an association between PGE₂ inhibition and failure of cells to phenotypically mature in response to P. brasiliensis. We conclude that a P. brasiliensis evasion mechanism exists associated to a dysregulation on DC maturation. These findings may provide novel information for the understanding of the complex interplay between the host and this fungus.     

A rapid method for cloning and sequencing variable-region genes of expressed immunoglobulins

A rapid procedure is described for cloning immunoglobulin V region genes from cells that express them. cDNA is synthesized from mRNA template using primers homologous to the immunoglobulin constant-region genes. Blunt-ended, double-stranded cDNA is obtained by sequential addition of enzymes to a single tube. The cDNA is inserted directly into the M13 vector, which is screened by plaque lifting for the presence of specific inserts. Screening probes can be generated from 32P-labeled single-stranded cDNAs generated from primers different from those used for cloning, or alternatively, from previously cloned V or C gene segments. The ease of cloning a cDNA V region is directly related to the abundance of Ig-specific mRNA within the cell of interest. This method minimizes the number of steps and the time needed to obtain accurate and complete sequences of any expressed Ig V region gene.     

Microbial Symbionts Accelerate Wound Healing via the Neuropeptide Hormone Oxytocin

Wound healing capability is inextricably linked with diverse aspects of physical fitness ranging from recovery after minor injuries and surgery to diabetes and some types of cancer. Impact of the microbiome upon the mammalian wound healing process is poorly understood. We discover that supplementing the gut microbiome with lactic acid microbes in drinking water accelerates the wound-healing process to occur in half the time required for matched control animals. Further, we find that Lactobacillus reuteri enhances wound-healing properties through up-regulation of the neuropeptide hormone oxytocin, a factor integral in social bonding and reproduction, by a vagus nerve-mediated pathway. Bacteria-triggered oxytocin serves to activate host CD4+Foxp3+CD25+ immune T regulatory cells conveying transplantable wound healing capacity to naive Rag2-deficient animals. This study determined oxytocin to be a novel component of a multi-directional gut microbe-brain-immune axis, with wound-healing capability as a previously unrecognized output of this axis. We also provide experimental evidence to support long-standing medical traditions associating diet, social practices, and the immune system with efficient recovery after injury, sustained good health, and longevity.     

An immunoelectron-microscopical observation of mouse juxtaglomerular cells in the case of experimental hydronephrosis.

Changes in juxtaglomerular (JG; renin-containing) cells in experimental hydronephrosis 1 month after ureteral ligation were investigated with immunoelectron-microscopical techniques. Two types of granules, electron dense (D) and lucent (L), were observed. D type granules were labeled more intensely with gold particles than those of L type. Granules intermediate between D and L types and exocytosis of D types were observed. In the cells containing D types exclusively, gold particles were restricted to the granules, whereas in the cells containing both D and L type granules, the particles were scattered throughout the cytoplasmic cytosol. The authors discuss the mechanisms of renin release in JG cells.     

Activation of Integrin αVβ3 Regulates Cell Adhesion and Migration to Bone Sialoprotein

α_Vβ₃, a broadly distributed member of the integrin family of adhesion receptors, has been implicated in a variety of physiological and pathophysiological events, including control of bone density, angiogenesis, apoptosis, tumor growth, and metastasis. Recently, it has been shown that activation of α_Vβ₃, its transition from a low- to a high-affinity/avidity state, influences its recognition of certain ligands. Bone sialoprotein (BSP) is recognized as an important ligand for α_Vβ₃ in processes ranging from bone formation to the homing of metastatic tumor cells. Here, the influence of α_Vβ₃ activation on the adhesion and migration of relevant cells to BSP has been examined. Stimulation of lymphoblastoid, osteoblastoid, and human umbilical vein endothelial cells (HUVEC) with PMA or Mn²⁺ markedly enhanced α_Vβ₃-dependent adhesion to BSP. α_Vβ₃-mediated migration of HUVEC or osteoblastic cells to BSP was substantially enhanced by stimulation, demonstrating that α_Vβ₃ activation enhances both adhesive and migratory responses. However, adhesion and/or migration of certain tumor cell lines, including M21 melanoma and MDA MB435 and SKBR3 breast carcinoma cell lines, to BSP was constitutively high and was not augmented by α_Vβ₃-activating stimuli. Inhibitors of the intracellular signaling molecules, phosphatidylinositol 3-kinase with wortmannin, hsp90-dependent kinases with geldanamycin, and calpain with calpeptin, but not MAPKK with PD98059, reduced the high spontaneous adhesion and migration of the M21 cells to BSP, consistent with the constitutive activation of the receptor on these tumor cells. These results indicate that the activation state of α_Vβ₃ can regulate cell migration and adhesion to BSP and, by extension, to other ligands of this receptor. The constitutive activation of α_Vβ₃ on neoplastic cells may contribute to tumor growth and metastatic potential.     

Low-temperature electron paramagnetic resonance study of the ferricytochrome c-cardiolipin complex

The electron paramagnetic resonance spectrum of the ferricytochrome c complex with cardiolipin was observed at temperatures below 20 K. For the low-spin iron(III) heme system complexed with the negatively charged lipid, the tetragonal and rhombic ligand field parameters (delta/lambda = 3.58, V/lambda = 1.82) differ significantly from those (delta/lambda = 2.53, V/lambda = 1.49) of the free ferricytochrome c sample. The g values of the complex (gx = 1.54 +/- 0.02, gy = 2.26 +/- 0.01, gz = 3.02 +/- 0.01) are compared to the values for free ferricytochrome c (gx = 1.25 +/- 0.02, gy = 2.25 +/- 0.01, gz = 3.04 +/- 0.01). Spectral alterations are interpreted in terms of the ligand field changes induced within the heme group by association with the negatively charged phosphoglyceride.     

Spin label study of erythrocyte deformability. Ca2+-induced loss of deformability and the effects of stomatocytogenic reagents on the deformability loss in human erythrocytes in shear flow

The Ca2+-induced loss of deformability in human erythrocytes and the recovery of the lost deformability by stomatocytogenic reagents were investigated by means of a new flow electron paramagnetic resonance (EPR) spin label method, which provides information on deformation and orientation characteristics of spin labeled erythrocytes in shear flow. The Ca2+-induced loss of deformability is attributed mainly to the increase in intracellular viscosity resulting from efflux of intracellular potassium ions and water (Gardos effect). Partial recovery of the lost deformability is demonstrated in the presence of stomatocytogenic reagents, such as chlorpromazine, trifluoperazine, W-7, and calmidazolium (R24571). The recovery can not be explained solely by suppression of the Gardos effect due to the reagents. Incorporation of an optimal amount of the reagents into the membrane appears to compensate for the membrane modification due to Ca2+ ions to restore a part of the lost deformability.     

Preparation and application of a fluorogenic substrate for endo-beta-xylosidase

The present paper describes a fluorometric assay for galactosaminoglycan-degrading endo-beta-xylosidase, utilizing glycosaminoglycan chains bearing a 4-methylumbelliferyl group at the reducing terminus as a substrate. This fluorogenic substrate is synthesized by human skin fibroblasts cultured in the presence of a fluorogenic xyloside, 4-methylumbelliferyl-beta-D-xyloside. The assay is based on measurement of the fluorescence of 4-methylumbelliferone, enzymatically liberated from the synthetic substrate by endo-beta-xylosidase. We examined the applicability of the assay for analysis of endo-beta-xylosidase activity.     

Cytostatic effect of antiestrogens in lymphoid cells: relationship to high affinity antiestrogen-binding sites and cholesterol

The antiproliferative effect of 10(-6) M antiestrogens in an estrogen receptor-negative lymphoid cell line (K36) was enhanced in lipoprotein-poor growth medium. The enhancement was not due to increased bioavailability because cellular uptake of [3H]tamoxifen was not increased and the lipoprotein fraction of serum had negligible [3H]tamoxifen-binding capacity. Cholesterol and lipoproteins, but not mevalonate, reversed the cytostatic effect of antiestrogens. Reversal by cholesterol was dose-related (10(-7) M to 10(-5) M), while that by lipoproteins could also be demonstrated in medium undepleted of lipoproteins. The cytostatic efficacy of a series of ten compounds correlated well with their relative binding affinities for solubilized antiestrogen-binding sites from K36 cells when log IC50 values (concentration required to reduce [3H]thymidine incorporation by 50%) were plotted against log RBA50 values (concentration required to reduce [3H]tamoxifen binding by 50%) (correlation coefficient 0.94). Transmission electron microscopy of antiestrogen-treated cells showed evidence of disordered cytokinesis which was partially reversed by cholesterol. These observations implicate the antiestrogen-binding protein in the antiproliferative effect of antiestrogens in nonestrogen target cells.