Circadian rhythms in the hypothalamo-pituitary-adrenal (HPA) axis

The pronounced daily variation in the release of adrenal hormones has been at the heart of the deciphering and understanding of the circadian timing system. Indeed, the first demonstration of an endocrine day/night rhythm was provided by Pincus (1943), by showing a daily pattern of 17-keto-steroid excretion in the urine of 7 healthy males. Twenty years later the adrenal gland was one of the very first organs to show, in vitro, that circadian rhythmicity was maintained. In the seventies, experimental manipulation of the daily corticosterone rhythm served as evidence for the identification of respectively the light- and food-entrainable oscillator. Another 20 years later the hypothalamo-pituitary-adrenal (HPA)-axis was key in furthering our understanding of the way in which rhythmic signals generated by the central pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) are forwarded to the rest of the brain and to the organism as a whole. To date, the adrenal gland is still of prime importance for understanding how the oscillations of clock genes in peripheral tissues result in functional rhythms of these tissues, whereas it has become even more evident that adrenal glucocorticoids are key in the resetting of the circadian system after a phase-shift. The HPA-axis thus still is an excellent model for studying the transmission of circadian information in the body.

Effects of constant and cyclic heat stress on muscle metabolism and meat quality of broiler breast fillet and thigh meat

This study investigated the effects of constant and cyclic heat stress on muscle metabolism and meat quality of broiler breast fillet and thigh meat from 4 to 6 wk of age. Male Arbor Acres (AA) broilers (n = 270, 4 wk old) were raised under different temperature conditions: standard (temperature was 23°C); constant high temperature (temperature was 34°C); and cyclic high temperature (temperature was 36°C from 1000 h to 1600 h and 23°C from 1600 h to 1000 h). On d 42, broilers were stunned and sampled. The results showed that chronic high temperature significantly decreased the proportion of breast muscle and significantly increased the proportion of thigh muscle (P < 0.05). The moisture concentration was significantly higher in the breast muscle of the birds exposed to constant high temperature (P < 0.05), whereas the protein content was significantly lower (P < 0.05) and fat deposition was significantly higher (P < 0.05) in the breast muscle of the birds exposed to constant or diurnal cyclic high temperature than those grown under standard temperature. The breast and thigh muscle of the birds grown under constant high temperature had significantly higher lightness, cook loss, and shear force (P < 0.05) and significantly lower initial pH (pH(i)), ultimate pH (pH(u)), and redness compared with those grown under standard temperature (P < 0.05). The pH(i), pH(u), and redness were significantly lower (P < 0.05) while the lightness and shear force were significantly higher for the breast muscle of the chickens raised under diurnal cyclic high temperature (P < 0.05) than those grown under standard temperature. In contrast, lightness and yellowness of thigh muscle were significantly higher (P < 0.05) in the chickens grown under diurnal cyclic high temperature than under standard temperature. Breast and thigh muscle of broilers exposed to constant high temperature produced higher (P < 0.05) lactic acid and pyruvate kinase activities than those exposed to the standard temperature. These results indicated that chronic heat stress significantly increased lactate production, reduced meat pH value by accelerating meat glycolysis, and eventually reduced meat quality.

Dendritic cells genetically engineered to express Fas ligand induce donor-specific hyporesponsiveness and prolong allograft survival

Polarization of an immune response toward tolerance or immunity is dictated by the interactions between T cells and dendritic cells (DC), which in turn are modulated by the expression of distinct cell surface molecules, and the cytokine milieu in which these interactions are taking place. Genetic modification of DC with genes coding for specific immunoregulatory cell surface molecules and cytokines offers the potential of inhibiting immune responses by selectively targeting Ag-specific T cells. In this study, the immunomodulatory effects of transfecting murine bone marrow-derived DC with Fas ligand (FasL) were investigated. In this study, we show that FasL transfection of DC markedly augmented their capacity to induce apoptosis of Fas+ cells. FasL-transfected DC inhibited allogeneic MLR in vitro, and induced hyporesponsiveness to alloantigen in vivo. The induction of hyporesponsiveness was Ag specific and was dependent on the interaction between FasL on DC and Fas on T cells. Finally, we show that transfusion of FasL-DC significantly prolonged the survival of fully MHC-mismatched vascularized cardiac allografts. Our findings suggest that DC transduced with FasL may facilitate the development of Ag-specific unresponsiveness for the prevention of organ rejection. Moreover, they highlight the potential of genetically engineering DC to express other genes that affect immune responses.

Modulation of transcription factor Sp1 by cAMP-dependent protein kinase

Transcription factor Sp1 is a phosphoprotein whose level and DNA binding activity are markedly increased in doxorubicin-resistant HL-60 (HL-60/AR) leukemia cells. The trans-activating and DNA binding properties of Sp1 in HL-60/AR cells are stimulated by cAMP-dependent protein kinase (PKA) and PKA agonists and inhibited by PKA antagonists as well as by the PKA regulatory subunit. Reporter gene activity under the control of the Sp1-dependent SV40 promoter is stimulated in insect cells transiently expressing Sp1 and PKA, and the DNA binding activity of recombinant Sp1 is activated by exogenous PKA in vitro. These results indicate that Sp1 is a cAMP-responsive transcription factor and that Sp1-dependent genes may be modulated through a cAMP-dependent signaling pathway.

Effects of sex hormones on mesangial cell proliferation and collagen synthesis

In a variety of renal diseases, males progress at a more rapid rate and have a more fulminant course than females. This gender difference may be related to the direct effects of sex hormones on the cells of the kidney. To evaluate this hypothesis, we studied the effects of estrogens and testosterone on mesangial cell proliferation and collagen synthesis. At 48 hours, estradiol at 10 nM and 100 nM had a modest proliferative effect on cultured mesangial cells, as measured by 3H thymidine incorporation into DNA and direct cell counting. This estradiol effect was fully reversed by Tamoxifen (1 microM). Estradiol had no effect on cellular proliferation at 1 microM concentrations, but suppressed proliferation at 10 microM doses. Testosterone had a modest but statistically insignificant effect on proliferation at 10 nM and 100 nM concentrations but no effect at 1 microM or 10 microM. Neither estradiol nor testosterone at 10 microM affected total cellular protein accumulation. Estradiol at 1 microM and 10 microM, markedly suppressed total collagen synthesis as measured by 3H proline incorporation, and specifically suppressed the synthesis of collagen types I and IV, as measured by immunoprecipitation and gel electrophoresis. Testosterone did not affect collagen synthesis. Estradiol also reduced the steady state message for the alpha 2 chain of type I collagen, while testosterone had no effect. Neither estradiol nor testosterone affected the steady state message for TGF beta or EGF. The direct effects of estradiol on mesangial cell collagen generation may help explain the slower development of glomerulosclerosis in women and therefore the "protective" effect of female gender on the progression of renal disease.

Acidic fibroblast growth factor in the developing rat embryo

Compared to basic fibroblast growth factor (bFGF), a widely distributed, broad spectrum mitogen and mesoderm inducer, acidic fibroblast growth factor (aFGF) is reported to have an essentially neural distribution and to be undetectable in the early embryo. In the present investigation, we used immunoblotting and immunochemistry to assess the cellular and tissue distributions of aFGF and bFGF in 11-20-d rat embryos. Immunoblotting of crude and heparin-bound embryo extracts revealed faint bands at the expected 17-18-kD and predominant bands at an apparent molecular mass of 26 to 28-kD (despite reducing conditions) using multiple specific antibodies for aFGF and bFGF. Pretreatment with 8 M urea yielded 18-20-kD aFGF and bFGF and some 24-26-kD bFGF. Immunoreactivity for both aFGF and bFGF was positive and similar in the cytoplasm, nuclei, and extracellular matrix of cells of neuroectodermal and mesodermal origin, while it was negative in endoderm-derived cells. The distribution of immunoreactive aFGF and bFGF also showed changes during development that were associated with the process of cellular and tissue differentiation. For example, intensity and extent of immunoreactivity for both peptides progressively increased in the middle layer of the spinal cord with increasing differentiation of the neural cells. The immunostaining patterns were very similar for aFGF and bFGF for each organ and at each stage. In conclusion, high molecular mass forms of immunoreactive aFGF and bFGF are present in the rat embryo. Acidic FGF and bFGF are both widely distributed in tissues of neuroectodermal and mesodermal origin, and their distribution was very similar.

Alginate encapsulant incorporating CXCL12 supports long-term allo- and xenoislet transplantation without systemic immune suppression

Islet transplantation represents a potentially curative approach for individuals with Type I Diabetes. The requirement for systemic immune suppression to control immune-mediated rejection of transplanted islets and the limited human islet supply represent significant roadblocks to progress for this approach. Islet microencapsulation in alginate offers limited protection in the absence of systemic immunosuppression, but does not support long-term islet survival. The chemokine, CXCL12, can repel effector T cells while recruiting immune-suppressive regulatory T cells (Tregs) to an anatomic site while providing a prosurvival signal for beta-cells. We proposed that coating or encapsulating donor islets with CXCL12 would induce local immune-isolation and protect and support the function of an allo- or xenograft without systemic immune suppression. This study investigated the effect of alginate microcapsules incorporating CXCL12 on islet function. Islet transplantation was performed in murine models of insulin-dependent diabetes. Coating of islets with CXCL12 or microencapsulation of islets with alginate incorporating the chemokine, resulted in long-term allo- and xenoislet survival and function, as well as a selective increase in intragraft Tregs. These data support the use of CXCL12 as a coating or a component of an alginate encapsulant to induce sustained local immune-isolation for allo- or xenoislet transplantation without systemic immunosuppression.

Sex hormones and renal nitric oxide synthases

The present study was undertaken to determine whether sex hormones influence nitric oxide synthase levels in the kidney. Five groups of rats were studied: males, castrated males, females, oophorectomized females, and oophorectomized females receiving estradiol replacement therapy. Endothelial nitric oxide synthase (eNOS) levels in the kidney were measured by Western blotting. eNOS levels were significantly greater in the renal medulla of female rats compared with male rats (3545 +/- 473 versus 2418 +/- 205 densitometry units (DU), P < 0.05). Oophorectomy reduced renal medullary eNOS levels to that of intact male rats (2566 +/- 304 DU, P = NS). Estrogen replacement therapy significantly increased medullary eNOS levels in oophorectomized animals (3249 +/- 377 versus 2302 +/- 213 DU, P < 0.05). Renal inducible nitric oxide synthase (iNOS) levels were measured after induction with lipopolysaccharide. iNOS levels were significantly greater in the renal medulla of female rats compared with male rats (677 +/- 253 versus 252 +/- 12 DU, P < 0.05). Oophorectomy reduced renal medullary iNOS levels to that of intact male rats (295 +/- 57 DU, P = NS). In contrast, estrogen replacement therapy significantly increased medullary iNOS levels in oophorectomized animals (682 +/- 356 versus 160 +/- 92 DU, P < 0.05). Steady-state levels of mRNA for iNOS were found to be higher in the inner medulla of female rats compared with male rats (1519 +/- 211 versus 899 +/- 105 DU, P < 0.05). In contrast to these findings, sex hormones failed to influence nitric oxide production or iNOS levels in lipopolysaccharide-stimulated mesangial cells in culture. These results suggest that gender may influence renal medullary synthesis of nitric oxide.

Selective estrogen receptor modulators suppress mesangial cell collagen synthesis

Estrogen receptor modulators (SERMs) are "designer drugs" that exert estrogen-like actions in some cells but not in others. We examined the effects of the SERMs LY-117018 (an analog of raloxifene) and tamoxifen on mesangial cells synthesis of type I and type IV collagen. We found that LY-117018 and tamoxifen suppressed mesangial cell type IV collagen gene transcription and type IV collagen protein synthesis in a dose-dependent manner, with a potency identical to that of estradiol. Type I collagen synthesis was also suppressed by LY-117018 in a dose-dependent manner with a potency identical to that of estradiol but greater than that of tamoxifen. Genistein, which selectively binds to estrogen receptor-beta in nanomolar concentrations, suppressed type I and type IV collagen synthesis, suggesting that estrogen receptor-beta mediates the effects of estrogen on collagen synthesis. Because matrix accumulation is central to the development of glomerulosclerosis, second-generation SERMs may prove clinically useful in ameliorating progressive renal disease without the adverse effects of estrogen on reproductive tissues.

A transforming growth factor beta 1 receptor type II mutation in ulcerative colitis-associated neoplasms

BACKGROUND & AIMS

Numerous gastrointestinal tumors, notably sporadic and ulcerative colitis (UC)-associated colorectal carcinomas and dysplasias, gastric cancers, and esophageal carcinomas, manifest microsatellite instability. Recently, a transforming growth factor beta 1 type II receptor (TGF-beta 1RII) mutation in a coding microsatellite was described in colorectal carcinomas showing instability. One hundred thirty-eight human neoplasms (61 UC-associated, 35 gastric, 26 esophageal, and 16 sporadic colorectal) were evaluated for this TGF-beta 1RII mutation.

METHODS

Whether instability was present at other chromosomal loci in these lesions was determined. In lesions manifesting or lacking instability, the TGF-beta 1RII coding region polydeoxyadenine (poly A) microsatellite tract was polymerase chain reaction amplified with 32P-labeled deoxycytidine triphosphate. Polymerase chain reaction products were electrophoresed on denaturing gels and exposed to radiographic film.

RESULTS

Three of 18 UC specimens with instability at other chromosomal loci (17%) showed TGF-beta 1RII poly A tract mutation, including 2 cancers and 1 dysplasia; moreover, 2% of UC specimens without instability (1 of 43) (1 cancer), 81% of unstable sporadic colorectal cancers (13 of 16), and none of the 61 stable or unstable gastric or esophageal cancers contained TGF-beta 1RII mutations.

CONCLUSIONS

Mutational inactivation of the poly A microsatellite tract within TGF-beta 1RII occurs early and in a subset of unstable UC neoplasms and commonly in sporadic colorectal cancers but may be rare in unstable gastric and esophageal tumors.

Effects of tumor necrosis factor-alpha on human trophoblast cell adhesion and motility

PROBLEM

Adhesive interaction between trophoblast cells and uterine endometrial basement membrane is one of the critical processes in embryo implantation. This interaction is directly or indirectly regulated by hormones, growth factors, and cytokines. Since tumor necrosis factor-alpha (TNF-alpha) is synthesized by both decidual and trophoblast cells, we hypothesized that TNF-alpha may play a regulatory role in trophoblast cell invasion. To test this hypothesis, we have used in vitro models to determine the effect of TNF-alpha on human trophoblast cell adhesion and motility, two major steps in trophoblast invasion.

METHODS

The effect of TNF-alpha on the motility of extended-lifespan first trimester trophoblasts (HTR) and JEG-3 choriocarcinoma cells was tested using the phagokinetic track motility assay. An in vitro adhesion assay was used to determine the effect of TNF-alpha on the adhesion of HTR and JEG-3 cells to laminin, a major basement membrane component. In addition, the effect of TNF-alpha on the surface expression of the laminin receptor beta 1 integrin subunit was examined using flow cytometry.

RESULTS

HTR or JEG-3 cells strongly adherent to laminin which was not significantly altered by TNF-alpha treatment. We also measured the effect of TNF-alpha on the surface expression of beta 1 integrin on HTR and JEG-3 cells; no difference was observed between control and treatment groups. Interestingly, the motility of both HTR and choriocarcinoma JEG-3 cells was significantly inhibited by TNF-alpha.

CONCLUSIONS

The role of TNF-alpha in human embryo implantation is currently unknown. Our data demonstrate that TNF-alpha does alter trophoblast cell adhesion to laminin, but significantly inhibits trophoblast cell motility in vitro, suggesting that TNF-alpha may play a regulatory role in trophoblast cell invasion.

Intragenic mutations of CDKN2B and CDKN2A in primary human esophageal cancers

The CDKN2A and CDKN2B genes, encoding p16 and p15 respectively, are located on chromosome 9p21, a locus at which frequent homozygous and heterozygous deletions occur in many primary human tumors, including esophageal carcinoma. CDKN2A and CDKN2B inhibit cyclin dependent kinase 4 (CDK4) and CDK6 and control cellular proliferation by preventing entry into the S phase of the cell cycle. Their inactivation may contribute to uncontrolled growth in human cancer. We previously described CDKN2A exon 2 mutations in a pilot study of 43 esophageal cancers. In order to determine whether CDKN2A and CDKN2B are frequent targets of 9p21 deletion in esophageal carcinogenesis, we have now analyzed 60 primary esophageal cancers for mutations in both exons 1 and 2 of CDKN2A and CDKN2B by direct sequencing of PCR amplified genomic DNAs. In conjunction with our previously published data, we have identified a total of eight nucleic acid substitutions among 60 esophageal carcinomas; here, we describe one new CDKN2B nonsense mutation and one new silent CDKN2B mutation that occurred somatically. Taken together, these results suggest that intragenic mutations in CDKN2A and CDKN2B occur in esophageal cancer, but that they are infrequent events. In view of the known high frequency of loss of heterozygosity at the chromosome 9p21 locus in esophageal cancers, the current data suggest that intragenic mutation is not the predominant mode of inactivation of CDKN2A and CDKN2B or that other genes are targets of deletion at this locus in these cancers.

Identification and characterization of a new splicing variant of vascular endothelial growth factor: VEGF183

We report the discovery of a new splicing variant of vascular endothelial growth factor named VEGF183. It is six amino acids shorter than its closest relative, VEGF189, due to the utilization of a conserved alternate splicing donor site within exon 6a. Highly expressed in heart tissue, VEGF183 is detected in transiently transfected COS cells as 28-32-kDa monomers under reduced condition, and 46-kDa dimers under non-reduced condition - the functional unit for all VEGF isoforms.

Protein kinase CK2 mediates TGF-beta1-stimulated type IV collagen gene transcription and its reversal by estradiol

BACKGROUND

We have previously shown that the transcription factor Sp1 mediates the stimulatory effects of transforming growth factor-beta1 (TGF-beta1) on type IV collagen gene transcription and protein synthesis, and that estradiol reverses these effects by down-regulating Sp1 activity. Protein kinase casein kinase II (CK2) phosphorylates Egr-1 and prevents its binding to Sp1. We hypothesized that TGF-beta1 stimulates CK2 activity, which in turn activates type IV collagen gene transcription via increased availability of free Sp1.

METHODS

The effects of TGF-beta1 and of estradiol on murine mesangial cell type IV collagen gene transcription were measured using a reporter mini gene construct and on collagen IV protein synthesis by Western blotting. Nuclear Egr-1, phosphorylated Egr-1, Sp1, Egr-1/Sp1 complexes and unbound Sp1 were measured using co-immunoprecipitation and Western blotting techniques.

RESULTS

TGF-beta1 stimulated CK2 activity in murine mesangial cells. Although TGF-beta1 failed to alter total Egr-1 protein, it increased phosphorylated Egr-1. This led to decreased Egr-1/Sp1 complex formation, increased unbound Sp1, increased binding of nuclear extracts to the collagen IV promoter, and increased type IV collagen gene transcription and protein synthesis. Physiologic concentrations of estradiol reversed these effects.

CONCLUSIONS

These studies suggest that activation of CK2 mediates the stimulatory effect of TGF-beta1 on type IV collagen gene transcription. Moreover, the ability of estradiol to reverse TGF-beta1-stimulated type IV collagen synthesis is mediated by down-regulating CK2 activity, which ultimately limits the availability of unbound Sp1 to activate gene transcription.

Estradiol suppresses type I collagen synthesis in mesangial cells via activation of activator protein-1

BACKGROUND

Estradiol suppresses the synthesis of type I collagen by murine mesangial cells. However, neither the alpha 1(I) nor the alpha 2(I) collagen gene contains an estrogen-response element. Because estradiol modulates the transcription of several genes that lack an estrogen-response element but contain a regulatory activator protein-1 (AP-1) binding motif, we hypothesized that AP-1 may mediate estradiol-induced suppression of type I collagen synthesis.

METHODS

We measured type I collagen synthesis in murine mesangial cells exposed to estradiol, phorbol 12-myristate 13-acetate (an activator of AP-1), or curcumin (an inhibitor of AP-1). We also assessed the effects of estradiol on the steady-state level of c-fos and c-jun mRNA and on the binding of mesangial cell nuclear extracts to an AP-1 consensus binding site oligonucleotide.

RESULTS

Estradiol (10(-10) M to 10(-7) M) suppressed type I collagen synthesis by murine mesangial cells in a dose-dependent manner (10(-7) M, 43.7 +/- 8.2% of control values, P < 0.001). Phorbol 12-myristate 13-acetate (10 microM, four-hr exposure) also decreased type I collagen in the media. In contrast, curcumin (1 microM) increased type I collagen. Estradiol increased the steady-state level of c-fos mRNA twofold at 30 minutes, with a return to basal levels at one hour. This was associated with a greater than threefold increase in the binding of nuclear extracts from estradiol-treated mesangial cells to an AP-1 consensus binding site oligonucleotide. Estradiol-enhanced binding of nuclear extracts to the AP-1 oligonucleotide was reversed by cycloheximide.

CONCLUSIONS

These data suggest that estradiol suppresses collagen I synthesis by murine mesangial cells via enhanced AP-1 activity.

Evaluation of traumatic subarachnoid hemorrhage using susceptibility-weighted imaging

BACKGROUND AND PURPOSE

SWI is an MR imaging technique that is very sensitive to hemorrhage. Our goal was to compare SWI and CT to determine if SWI can show traumatic SAH in different parts of the subarachnoid space.

MATERIALS AND METHODS

Twenty acute TBI patients identified by CT with SAH underwent MR imaging scans. Two neuroradiologists analyzed the CT and SWI data to decide whether there were SAHs in 8 anatomical parts of the subarachnoid space.

RESULTS

Fifty-five areas with SAH were identified by both CT and SWI. Ten areas were identified by CT only and 13 by SWI only. SAH was recognized on SWI by its very dark signal intensity surrounded by CSF signal intensity in the sulci or cisterns. Compared with the smooth-looking veins, SAH tended to have a rough boundary and inhomogeneous signal intensity. In many instances, blood in the sulcus left an area of signal intensity loss that had a "triangle" shape. SWI showed 5 more cases of intraventricular hemorrhage than did CT.

CONCLUSIONS

SAH can be recognized by SWI through its signal intensity and unique morphology. SWI can provide complementary information to CT in terms of small amounts of SAH and hemorrhage inside the ventricles.

Clinical analysis of cervical lymph node metastasis risk factors in patients with papillary thyroid microcarcinoma

PURPOSE

Lymph node metastasis (LNM) is a vital prognosis factor in patients with papillary thyroid microcarcinoma (PTMC). The study tried to identify clinicopathological factors for LNM of PTMC.

METHODS

The clinicopathological data of 1031 patients with PTMC were extracted and analyzed. Univariate and multivariate analyses were used to identify risk factors associated with cervical lymph node metastasis. ROC analysis was used to determine the ideal critical points of the sum of the maximum diameter of multifocal in a unilateral lobe.

RESULTS

The probability of LNM, central lymph node metastasis (CLNM) and lateral lymph node metastasis(LLNM)of PTMC patients were 35.6, 33.7 and 5.6%, respectively. In addition, 1.9% PTMC had LLNM only. Male, age ≤ 40 years, tumor largest diameter ≥ 5 mm, multifocal, non-uniform echoic distribution, the sum of the maximum diameter of multifocal in a unilateral lobe ≥ 8.5 mm, tumors in the lower pole location were prone to CLNM. Ultrasound mix-echo, the sum of the maximum diameter of the multifocal ≥ 10.75 mm, tumors in the upper pole location were extremely prone to LLNM. T3 were prone to LLNM or skip LLNM.

CONCLUSIONS

According to the clinicopathological characteristics of PTMC, the cervical lymph nodes should be correctly evaluated to guide the surgical treatment.

Evidence of a role for CD200 in regulation of immune rejection of leukaemic tumour cells in C57BL/6 mice

Increased expression of the molecule CD200 in mice receiving renal allografts is associated with immunosuppression leading to increased graft survival, and altered cytokine production in lymphocytes harvested from the transplanted animals. Preferential production of IL-4, IL-10 and TGFbeta occurs on donor-specific restimulation in vitro, with decreased production of IL-2, IFNgamma and TNFalpha. These effects are enhanced by simultaneous infusion of CD200 immunoadhesin (CD200Fc) and donor CD200 receptor (CD200r) bearing macrophages to transplanted mice. C57BL/6 mice do not normally resist growth of EL4 or C1498 leukaemia tumour cells. Following transplantation of cyclophosphamide-treated C57BL/6 with T-depleted C3H bone marrow cells, or for the EL4 tumour, immunization of C57BL/6 mice with tumour cells transfected with a vector encoding the co-stimulatory molecule CD80 (EL4-CD80), mice resist growth of tumour challenge. Immunization of C57BL/6 mice with EL4 cells overexpressing CD86 (EL4-CD86) is ineffective. Protection from tumour growth in either model is suppressed by infusion of CD200Fc, an effect enhanced by co-infusion of CD200r+ macrophages. CD200Fc acts on both CD4+ and CD8+ cells to produce this suppression. These data are consistent with the hypothesis that immunosuppression following CD200-CD200r interaction can regulate a functionally important tumour growth inhibition response in mice.

PPE protein (Rv3425) from DNA segment RD11 of Mycobacterium tuberculosis: a potential B-cell antigen used for serological diagnosis to distinguish vaccinated controls from tuberculosis patients

Proteins encoded by a 9.5-kb DNA segment, termed the region of difference (RD), of Mycobacterium tuberculosis have been demonstrated to be important in bacterial virulence, vaccine development and the design of diagnostic reagents. This study evaluated the immunogenic properties of Rv3425, a member of the PPE family of proteins, encoded by an open reading frame found in RD11 of M. tuberculosis, in comparison with two other well-known antigens, the early secreted antigen target 6 (ESAT-6) and the 10-kDa culture filtrate protein (CFP-10). RT-PCR demonstrated that Rv3425 mRNA is expressed in liquid culture by M. tuberculosis H37Rv. When tested in a conventional ELISA in the form of a His-tagged recombinant protein, Rv3425 revealed a statistically significant antigenic distinction between healthy bacille Calmette-Guérin (BCG)-vaccinated controls and tuberculosis (TB) patients (p <0.0001). The anti-IgG response to recombinant Rv3425 was almost equal to that for CFP-10, and was higher than that for ESAT-6. The results highlight the immunosensitive and immunospecific nature of Rv3425, which shows promise for use in the serodiagnosis of TB.

Expression, purification and characterization of recombinant mouse MT5-MMP protein products

We have recently identified the fifth member of the membrane-type matrix metalloproteinase subfamily, MT5-MMP/MMP24, which is expressed in a brain specific manner (Duanqing Pei (1999) J. Biol. Chem. 274, 8925-8932). To further characterize its enzymic properties, an expression construct was engineered to produce MT5-MMP as a soluble and active form by truncating its transmembrane domain. Stable expression cell lines were subsequently established from MDCK cells transfected with this construct. Unfortunately, purification of MT5-MMP from the culture media in large quantity proves to be difficult initially due to its rapid turnover via a mechanism which can be inhibited by a broad spectrum metalloproteinase inhibitor, BB94. Thus, BB94 was included in the cell culture medium and throughout the purification process except the final step of chromatography to protect MT5-MMP from destruction. Purified to homogeneity and free of the synthetic inhibitor, MT5-MMP can activate progelatinase A efficiently in a TIMP2 sensitive fashion. A preliminary screen for its potential substrates among extracellular matrix components identified the proteoglycans as the preferred substrates for MT5-MMP. Furthermore, it is determined that the stability of purified MT5-MMP is temperature dependent with rapid destruction at 37 degrees C, but being relatively stable at temperatures 4 degrees C or lower. These observations establish MT5-MMP as a proteoglycanase with a short half-life at body temperature, which may be critical for tightly controlled turnover of ECM components such as those in the brain.

Synergy in induction of increased renal allograft survival after portal vein infusion of dendritic cells transduced to express TGFbeta and IL-10, along with administration of CHO cells expressing the regulatory molecule OX-2

Dendritic cells (DC), generated from C57BL/6 mouse bone marrow cells cultured with GM-CSF and IL-4 for 9 days, were engineered to express constitutively the cytokines TGFbeta, IL-10, and IL-12, using adenovirus vectors constructed using an E1-deleted replication-deficient recombinant adenovirus carrying the appropriate cDNA for the relevant cytokines (Ad-TGFbeta, Ad-IL-12, or Ad-IL-10). C3H mice receiving nontransduced DC or pretransplant infusion of DC-Ad-LacZ showed increased survival of C57BL/6 renal grafts relative to that of control nonimmunized mice. Transfusion of Ad-IL-12-transduced DC abolished this increased survival, leading to a graft survival equivalent to that of controls with no DC. Optimal graft survival was seen in the group receiving a mixture of DC transduced with constructs for both IL-10 and TGFbeta. There was a correlation between increased graft survival and both inhibition of the induction of CTL and enhancement of a polarization to produce type-2 cytokines (IL-4, IL-10, and TGFbeta) on antigen-specific restimulation in vitro. These effects were more pronounced following concomitant infusion of CHO cells transfected with a full-length cDNA for murine OX-2.

An unexpected counter-regulatory role of IL-10 in B-lymphocyte-mediated transplantation tolerance

Monoclonal antibody against the CD45RB protein induces stable transplantation tolerance to multiple types of allograft. We have previously established that this tolerance protocol relies on the regulatory function of B lymphocytes for its effect. B lymphocytes have also been reported to participate in immune regulation in several other settings. In most of these systems, the regulatory function of B lymphocytes depends on the production of IL-10. Therefore, we investigated the role of IL-10 in the anti-CD45RB model of B-cell-mediated transplantation tolerance. Surprisingly, using antibody-mediated neutralization of IL-10, IL-10-deficient recipients and adoptive transfer of IL-10-deficient B lymphocytes, we found that IL-10 actually counter-regulates tolerance induced by anti-CD45RB. Furthermore, neutralization of IL-10 reduced the development of chronic allograft vasculopathy compared to anti-CD45RB alone and reduced the production of graft reactive alloantibodies. These data suggest that the participation of regulatory B lymphocytes in transplantation tolerance may be distinct from how they operate in other systems. Identifying the specific B lymphocytes that mediate transplantation tolerance and defining their mechanism of action may yield new insights into the complex cellular network through which antigen-specific tolerance is established and maintained.