Low interferon-gamma release in response to phytohemagglutinin predicts the high severity of diseases

A clinically useful immune biomarker could potentially assist clinicians in their decision making. We stimulated T-cell proliferation to secret interferon gamma (IFN-γ) by phytohemagglutinin, and then measured the production of IFN-γ (mitogen value [M value]). We aimed to determine the relationship between the M value, clinical severity, and outcomes of diseases.In all, 484 patients admitted to intensive care units were enrolled in this retrospective study. The Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were collected within the first 24 hours. M value, C-reaction protein (CRP), procalcitonin (PCT), erythrocyte sedimentation rate (ESR), and routine blood tests were analyzed and collected during the study.When APACHE II scores were greater than 15 and M values were less than 6, the hospital mortality rose in a straight line. There was an inverse correlation between APACHE II score and M value (rs = -0.212, P < .001). There was a positive correlation between M value and lymphocyte numbers (b' = 0.249, P < .001); however, there was an inverse correlation between M value and WBC (b' = -0.230, P < .001), and ESR (b' = -0.100, P = .029). Neurological diseases had the greatest influence on APACHE II scores (b' = 10.356, P < .001), whereas respiratory diseases had the greatest influence on M value (b' = 1.933, P < .001). Furthermore, in the respiratory system, severe pneumonia had a greater influence on M value. Taking the APACHE II score as the gold standard, the area under the curve of M was 0.632 (95% confidence interval [CI] 0.575-0.690, P < .001), PCT was 0.647 (95% CI 0.589-0.705, P < .001), CRP was 0.570 (95% CI 0.511-0.629, P = .022), and ESR was 0.553 (95% CI 0.494-0.612, P = .078). Divided by M value = 5, the positive predictive value of the M value is 37.22% (115/309) and negative predictive value is 75.43% (132/175).The results show that the M values, PCT, and CRP were better than ESR to predict the severity of diseases. The number and proportion of lymphocytes also affected the result of the M value. To a certain extent, the M value may be a clinically useful immune biomarker, which may help clinicians objectively evaluate the severity of diseases, especially in the respiratory system.

Assessment of human lymphocyte proliferation associated with metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS), a cluster of various metabolic conditions, has become epidemic and causes increased morbidity and mortality.

PURPOSE

The aim of this study was to compare lymphocyte proliferation under two different stimuli, Concanavalin A (ConA) and insulin, in a group of patients with MetS (Group 1) and a healthy group (Group 2).

METHODS

Group 1 consisted of 53 patients who met the diagnostic criteria for MetS. Group 2 consisted of 63 patients without MetS. All individuals were evaluated for lipid profile and glycemia. Lymphocyte extraction and culture were performed for each subject and lymphocyte proliferation was assessed using the Alamar blue technique.

RESULTS

There was no gender difference between both groups, but in terms of age, there was a significant difference. The use of Con A at concentrations of 1 and 5 µg/mL induced a high lymphocyte proliferation in both groups. In contrast, when different concentrations of insulin were added, no significant changes in lymphocyte proliferation were observed. However, the proliferation of lymphocytes was significantly higher in Group 1 compared to Group 2 under insulin stimulus, which did not happen under ConA stimulation. Even after age and gender correction, this difference was maintained.

CONCLUSIONS

The increased lymphocyte proliferative response to insulin in patients with MetS found in this study suggests a role of the lymphocyte response to insulin in the pathophysiology of MetS. This response may be used as an immuno-biological marker for MetS, although further studies to evaluate its clinical usefulness need to be conducted.

The protective role of myeloid-derived suppressor cells in concanavalin A-induced hepatic injury

The mechanism underlying T cell-mediated fulminant hepatitis is not fully understood. In this study, we investigated whether myeloid derived suppressor cells (MDSCs) could prevent the concanavalin A (ConA)-induced hepatitis through suppressing T cell proliferation. We observed an increase in the frequencies of MDSCs in mouse spleen and liver at early stage of ConA treatment, implicating that the MDSCs might be involved in the initial resistance of mice against ConA-mediated inflammation. Subpopulation analysis showed that the MDSCs in liver of ConA-induced mice were mainly granulocytic MDSCs. Adoptive transfer of the bone marrow-derived MDSCs into ConA-treated mice showed that the MDSCs migrated into the liver and spleen where they suppressed T cell proliferation through ROS pathway. In addition, the frequencies of MDSCs in mice were also significantly increased by the treatment with immune suppressor glucocorticoids. Transfer of MDSCs into the regulatory T cell (Treg)-depleted mice showed that the protective effect of MDSCs on ConA-induced hepatitis is Treg-independent. In conclusion, our results demonstrate that MDSCs possess a direct protective role in T cell-mediated hepatitis, and increasing the frequency of MDSCs by either adoptive transfer or glucocorticoid treatment represents a potential cell-based therapeutic strategy for the acute inflammatory disease.

T-cell responses in oiled guillemots and swans in a rehabilitation setting

Aquatic birds are commonly affected by oil spills. Despite rehabilitation efforts, the majority of rehabilitated common guillemots (Uria aalge) do not survive, whereas mute swans (Cygnus olor) tend to have higher postrelease survival. Polyaromatic hydrocarbons (PAHs) present in crude oil and diesel are immunotoxic in birds affecting cell-mediated responses to immunogens. Because it is a target of PAH toxicity, T-lymphocyte response to controlled mitogen administration (phytohemagglutinnin test) was investigated in a scoping study as a potentially useful minimally invasive in vivo test of cell-mediated immunity. The test was performed on 69 mute swans and 31 common guillemots stranded on the Norfolk and Lincolnshire coastline and inland waterways in England (UK) either due to injury or to contamination with crude or diesel oil. T-lymphocyte response was significantly decreased in swans with greater oil scores. T-lymphocyte responses were also decreased in guillemots, but this finding was not statistically significant.

Adenovirus-mediated viral interleukin-10 gene transfer prevents concanavalin A-induced liver injury

BACKGROUND AND AIM

Liver injury is closely associated with immune inflammation. Lacking immunostimulatory functions, viral interleukin-10 (vIL-10), a cellular IL-10 homologue, has been an attractive molecule for immunomodulatory therapy. We aimed to reveal a protective effect of the gene transfer of an adenoviral vector encoding vIL-10 on liver injury induced by concanavalin A.

METHODS

C57BL/6J mice were intravenously injected with adenoviral vector encoding vIL-10 before concanavalin A challenge. Liver injury was assessed. Interferon-γ and interleukin-4 levels were measured by ELISA. The activation of splenic and hepatic immune cells was analysed using an MTT assay.

RESULTS

Adenoviral vector encoding vIL-10 pretreatment significantly decreased concanavalin A-mediated elevations in serum alanine aminotransaminase and aspartate aminotransaminase activity, and necrotic area in liver tissues. The protective effect of adenoviral vector encoding vIL-10 was attributed to its inhibition of T cell activation, and production of interferon-γ and interleukin-4 by the immune cells. Recombinant mouse IL-10, a high homologous cytokine to vIL-10, effectively downregulated interferon-γ and interleukin-4 release by hepatic mononuclear cells.

CONCLUSION

Adenovirus vector-mediated vIL-10 gene transfer can prevent concanavalin A-induced hepatic injury, minimise pro-inflammatory cytokine release, and inhibit the activation of T lymphocytes.

Review on the in vitro interaction of insulin glargine with the insulin/insulin-like growth factor system: potential implications for metabolic and mitogenic activities

Insulin analogues provide clinically important benefits for people with diabetes, including more predictable action profiles and lower risk of hypoglycemia compared with human insulin. However, it has been suggested that certain insulin analogues may lead to greater activation of insulin-like growth factor-1 (IGF-1) signaling, with risk for adverse mitogenic effects. This article aims to critically review studies on the mitogenic effects of the insulin analogue insulin glargine (glargine) and its metabolites. A review of in vitro studies suggests that glargine may stimulate mitogenic activity in some cell lines at supraphysiological concentrations (nanomolar/micromolar concentrations). Mitogenicity appeared to be related to the expression of the IGF-1 receptor, being present in cells expressing high levels of the receptor and absent in cells with limited or no IGF-1 receptor expression. In animal studies, glargine did not promote tumor growth, despite administration at supraphysiological concentrations (nanomolar/micromolar), which are unlikely to be observed in clinical practice because the doses needed to produce these concentrations are liable to lead to hypoglycemia. Furthermore, glargine in vivo is rapidly transformed into its metabolites, the metabolic and mitogenic characteristics of which have been shown to be broadly equal to those of human insulin. Thus, the suggestion of increased relative mitogenic potency of insulin glargine seen in some cell lines does not appear to carry over to the in vivo situation in animals and humans.

Evaluation of Azathioprine on Lesion Severity and Lymphocyte Blastogenesis in Dogs With Perianal Fistulas

Fourteen dogs with perianal fistulas were entered into a prospective clinical study to investigate the effects of long-term azathioprine on clinical outcome and to determine if the clinical results correlated with lymphocyte blastogenesis tests. Complete remission of perianal fistulas was seen in eight (57%) of 14 dogs; partial remission occurred in one (7%) dog; and no response was detected in five (36%) dogs. The results of lymphocyte blastogenesis assays did not correlate with therapeutic response.

Rapid flow cytometric measurement of cytokine-induced phosphorylation pathways [CIPP] in human peripheral blood leukocytes

Current strategies designed to assess cells in the peripheral blood are limited to evaluation of phenotype or delayed measurement [>6 h] of function, usually quantifying cytokine production, cytolytic activity, or response to antigens. We reasoned that measurable abnormalities in signaling pathways could reflect pathological environs that cells experience in the setting of inflammatory states/cancer and could be represented in the peripheral blood. Two major pathways regulating the immune response are the JAK/STAT and MAPK/ERK pathways. These pathways are initiated by ligand-receptor binding and are rapidly propagated by subsequent protein phosphorylation cascades. We evaluated the brief application of cytokines in vitro to interrogate the early phosphorylation events of these signaling pathways in normal peripheral blood mononuclear cells (PBMC). Individual cytokine doses and time intervals of treatment were assessed to identify conditions useful in a clinical laboratory and as an initial goal to induce maximal phosphorylation. Surprisingly, all of the STAT proteins assessed and ERK1/2 are maximally phosphorylated within 15 min in human PBMC simply following addition of cytokines without preactivation of the cells. At 2 h, cells typically return to their basal phosphorylation states. For most of the cytokines tested, increased phosphorylation directly correlated with increased concentrations of the individual cytokines. These strategies will enable robust development of simple blood analyses to identify normal levels as well as impairments in STAT and MAPK/ERK signaling pathways associated with various human disease states including acute and chronic inflammatory conditions throughout clinical immunology.

Time- and dose-dependent mitogenic effect of basic fibroblast growth factor combined with different bone graft materials: an in vitro study

OBJECTIVES

In periodontal regeneration, the growth factor concentrations and the delivery system used are of great importance. In an attempt to assess the mitogenic effect of basic fibroblast growth factor (bFGF) on periodontal ligament (PDL) cells combined with different bone replacement materials, two allografts of cortical (DFDBA) and cancellous (DFBA) bone and an anorganic bovine material with a synthetic peptide (ABM P-15) were used. The purpose of this study was to evaluate the in vitro mitogenic effect of different doses of bFGF alone or in combination with DFDBA, DFBA and ABM P-15 on human PDL cells in a time-dependent mode.

MATERIAL AND METHODS

PDL cell cultures were derived from the mid-root of four maxillary premolars. Cells were grown and reached confluence. On day 2 of quiescence, new medium was added along with (1) 1, 5, 10 and 25 ng/ml of bFGF alone, (2) 10 mg of DFDBA, DFBA and ABM P-15 alone and (3) their combination. The mitogenic effect was determined at 24 and 48 h of culture by using a hemocytometer chamber. The cells were counted under a phase contrast microscope.

RESULTS

The results revealed that bFGF at the highest concentrations and after 48 h exerted a significant mitogenic effect on PDL cells, and also DFDBA and DFBA supported cell proliferation. Furthermore, DFDBA and DFBA enriched with bFGF had a significant mitogenic effect after 48 h of culture. ABM P-15 with 10 and 25 ng/ml of bFGF up-regulated PDL cell proliferation after 48 h of incubation.

CONCLUSIONS

The findings of this study demonstrate the beneficial role of bFGF combined with DFDBA and DFBA as carriers in periodontal repair.

Mitogenic effect of Carthamus lanatus extracts, fractions and constituents

Extracts, fractions and constituents of Carthamus lanatus were tested for their mitogenic effect on bone marrow cells in mice. Most of the studied samples inhibited cell proliferation and only the flavonoid glycoside rutin caused increasing of mitotic activity.

Selective elimination of hepatic natural killer T cells with concanavalin A improves liver regeneration in mice

BACKGROUND

Although concanavalin A (Con A) as a T cell stimulant can cause natural killer T (NKT) cell-mediated liver injury in mice and a nonhepatotoxic dose of Con A can trigger innate immune cells including NKT cells to prevent tumor metastasis in the liver, little is known about the role of Con A-primed NKT cells in liver repair. In this study, we aimed to investigate the effect of pretreatment with a nontoxic dose of Con A on subsequent liver regeneration in mice.

METHODS

A nontoxic dose of Con A was injected intravenously 24 h before partial hepatectomy (PHx), which was used as a model of liver regeneration. Ratios of remnant liver mass to body weight, bromodeoxyuridine (BrdU) incorporation and proliferating cell nuclear antigen (PCNA) labeling were used to assess liver regeneration.

RESULTS

Hepatic mononuclear cells were isolated and analyzed by flow cytometry. After PHx, the ratios of liver weight to body weight, PCNA-positive hepatocytes and BrdU-positive hepatocytes in Con A-pretreated mice were significantly higher than that of phosphate-buffered saline-treated mice, indicating that Con A pretreatment can accelerate liver regeneration. Flow cytometric analysis showed that NKT cells were significantly activated and selectively eliminated after the Con A administration. Moreover, NKT cells expressed more apoptosis-related molecules, Fas and Annexin V.

CONCLUSIONS

Taken together, Con A accelerates liver regeneration in mice by eliminating hepatic NKT cells via activation-induced cell death.

Mitogenic and chondrogenic effects of fibroblast growth factor-2 in adipose-derived mesenchymal cells

Adipose-derived mesenchymal cells (AMCs) have demonstrated a great capacity for differentiating into bone, cartilage, and fat. Studies using bone marrow-derived mesenchymal cells (BMSCs) have shown that fibroblast growth factor (FGF)-2, a potent mitogenic factor, plays an important role in tissue engineering due to its effects in proliferation and differentiation for mesenchymal cells. The aim of this study was to investigate the function of FGF-2 in AMC chondrogenic differentiation and its possible contributions to cell-based therapeutics in skeletal tissue regeneration. Data demonstrated that FGF-2 significantly promoted the proliferation of AMCs and enhanced chondrogenesis in three-dimensional micromass culture. Moreover, priming AMCs with treatment of FGF-2 at 10 ng/ml demonstrated that cells underwent chondrogenic phenotypic differentiation, possibly by inducing N-Cadherin, FGF-receptor 2, and transcription factor Sox9. Our results indicated that FGF-2 potentiates chondrogenesis in AMCs, similar to its functions in BMSCs, suggesting the versatile potential applications of FGF-2 in skeletal regeneration and cartilage repair.

Mechanisms and significance of bifunctional NK4 in cancer treatment

Based on the background that hepatocyte growth factor (HGF) and c-Met/HGF receptor tyrosine kinase play a definite role in tumor invasion and metastasis, NK4, four-kringles containing intramolecular fragment of HGF, was isolated as a competitive antagonist for the HGF-c-Met system. Independent of its HGF-antagonist action, NK4 inhibited angiogenesis induced by vascular endothelial cell growth factor and basic fibroblast growth factor, as well as HGF, indicating that NK4 is a bifunctional molecule that acts as an HGF-antagonist and angiogenesis inhibitor. Interestingly, kringle domains in distinct types of proteins, e.g., plasminogen, prothrombin, plasminogen activators, apolipoprotein(a), and HGF, share angioinhibitory actions. In experimental models of distinct types of cancers, NK4 protein administration or NK4 gene therapy inhibited tumor invasion, metastasis, and angiogenesis-dependent tumor growth. Cancer treatment with NK4 may prove to suppress malignant tumors to be 'static' in both tumor growth and spreading, as based on biological characteristics of malignant tumors.

Activation of p38 mitogen-activated protein kinase during ent-11alpha-hydroxy-16-kauren-15-one-induced apoptosis in human leukemia HL-60 cells

Kaurene-type diterpenes possess various biological activities including antitumor and anti-inflammatory effects. Indeed, we have found that an ent-kaurene diterpene, ent-11alpha-hydroxy-16-kauren-15-one (KD), induced apoptosis via caspase-8 activation in human promyelocytic leukemia HL-60 cells. However, the mechanism of caspase-8 activation by KD is not clear. In this study, we investigated the involvement of p38 mitogen-activated protein kinase (p38 (MAPK)) in KD-induced apoptosis. p38 (MAPK) was activated by treatment with KD parallel to DNA ladder formation. Pretreatment with SB203580, a specific inhibitor of p38 (MAPK), attenuated induction of apoptosis by KD and inhibited activation of caspase-8. Cleavage of Bid, a typical substrate of caspase-8, was also inhibited by treatment with SB203580, suggesting that activation of p38 (MAPK) occurs upstream of caspase-8 during KD-induced apoptosis.

Characterization of serotonin transporter in blood lymphocytes of rats. Modulation by in vivo administration of mitogens

Serotonin transporter sites were characterized in blood lymphocytes of rats. Pharmacological characteristics of drug interactions were in concordance with recent studies in nervous and human immune cells. The potency order of inhibition of [(3)H]paroxetine binding was imipramine>citalopram>alaproclate>serotonin. Selective inhibitors of dopamine or noradrenaline transporters did not inhibit it. The specific binding of [(3)H]paroxetine was higher at intermediate than at low concentrations, and the plot of free vs. specific binding had a sigmoid shape. The affinity constant or K(d), 1.77 nM, was in close agreement with data obtained from kinetic studies (K(d)=1.33 nM), which evidences that the equilibrium was reached. In addition, serotonin transporter was evaluated by lipopolysaccharide or concanavalin A administration in vivo (0.1 mg/kg, i.p., 18 h). After the treatment with lipopolysaccharide, no changes were observed in the numbers of sites or B(max) or in the affinity, K(d). The treatment with concanavalin A showed a significant reduction in B(max) and reduction in K(d). Additionally, serotonin and 5-hydroxyindoleacetic acid levels were determined in plasma and lymphocytes by high-performance liquid chromatography. Treatment with lipopolysaccharide produced a significant increased of serotonin levels in lymphocytes without changes in 5-hydroxyindoleacetic acid level; in plasma, it produced an increase in serotonin and 5-hydroxyindolacetic acid levels. In addition, serotonin synthesis was evaluated by adding 300 microM of tryptophan in the medium, which significantly increased serotonin levels in control lymphocytes. Moreover, the concentrations of 5-hydroxyindoleacetic acid was enhanced significantly, both in plasma and lymphocytes in the presence of tryptophan after treatment with lipopolysaccharide. The administration of concanavalin A significantly decreased plasma levels of serotonin, as well as the concentrations of serotonin and 5-hydroxyindoleacetic acid in lymphocytes. These results demonstrate the presence of serotonin transporter in lymphocytes of rat blood, the capacity for serotonin synthesis in lymphocytes, and the modulation of these parameters by systemic administration of mitogens. The findings of this work contribute to understanding the immunological role of serotonin and the communication of immune and nervous systems.

Salusins promote cardiomyocyte growth but does not affect cardiac function in rats

Salusin-alpha and -beta are newly found polypeptides that stimulate proliferation, hypotension and bradycardia in vascular smooth muscle cells (VSMCs) and fibroblasts. Propresalusin mRNA is widespread, and positive stains for salusins have been observed in many human tissues such as endothelium and ventricular tissue. To investigate the bio-effect of salusins on cardiovascular function, 20 nmol/kg salusin-alpha or 2 nmol/kg salusin-beta was intravenously (i.v.) injected into rats, and isolated rat hearts were perfused with 10(-12) to 10(-7) mol/l salusin-alpha or -beta. (45)Ca(2+) uptake and (3)H-Leucine incorporation were determined in cultured neonatal rat cardiomyocytes. Neither salusin-a nor -beta affected cardiac function in vivo or in vitro but salusin-beta decreased mean arterial blood pressure (MAP). The polypeptides' stimulation of (45)Ca(2+) uptake and (3)H-Leucine incorporation was concentration-dependent, and the incorporation was inhibited by nicardipine (Nic) and FK-506 [FK; an inhibitor of calcineurin (CaN)]. PD(98059) [PD; inhibitor of mitogen-activated protein kinase (MAPK)] and chelerythrine [inhibitor of protein kinase C (PKC)] inhibited salusin-stimulated (3)H-Leucine incorporation. Endothelin-1 (ET) synergistically increased salusin-induced (45)Ca(2+) uptake. Our results suggest that salusin-alpha and -beta did not directly affect cardiac function in the rat heart but that they improved calcium uptake and protein synthesis in neonatal rat cardiomyocytes through the calcium, calcineurin, MAPK and PKC signal pathways. Salusins may be regulatory factors for myocardial growth and hypertrophy.

Vaccination with plasmid DNA activates dendritic cells via Toll-like receptor 9 (TLR9) but functions in TLR9-deficient mice

We analyzed whether the immunobiology of vaccinating plasmid DNA containing a transcription unit for OVA is influenced by immunostimulatory CpG motifs in the plasmid backbone. Indeed, plasmid DNA differentially activated in vitro myeloid and plasmacytoid dendritic cells (DCs) provided they expressed the CpG-DNA receptor, Toll-like receptor 9 (TLR9). Dependent on the DC subset, activation resulted in type 1 IFN production, while both DC subsets produced IL-6 and up-regulated expression of costimulatory molecules CD40 and CD86. In vivo, however, even upon repeated vaccination with plasmid DNA, priming of OVA-specific CTL and clonal expansion of SIINFEKL-specific CD8 T cells were equal in TLR9-positive and TLR9- or MyD88-negative mice. Overall, these results negate a dominant role of CpG-DNA/TLR9 interactions in long-term vaccination protocols.

A mitogenic protein fraction in latex from Carica candamarcensis

Latex from Caricaceae contains a number of proteins believed to be part of a defense mechanism that protects these plants from wounding. Prior evidence suggests that some components in Carica papaya improve healing of ulcerous wounds in mammals. This study shows the chromatographic isolation of a protein fraction from C. candamarcensis that stimulates cell proliferation of mammalian cells by measuring MTT reduction and thymidine incorporation. The effect appears to be cell specific as L929, MDA-MB231 and BHK-21 cells are stimulated while no effect is seen on CHO cells. The maximal stimulatory effect reaches 2.2-fold 72 h after addition of the active fraction to L929, 1.8-fold in MDA-MB231 cells and 1.6-fold in BHK cells. Proteolytic inactivation of the active fraction suggests that a protein is responsible for the proliferative activity and its size is estimated between 10 and 25 kDa. A potential candidate for this function is a 23 kDa protein found in the fraction that reacts with human EGF antibody.

Hepatic stimulator substance administration ameliorates liver regeneration in an animal model of fulminant hepatic failure and encephalopathy

AIMS/BACKGROUND

Hepatic stimulator substance (HSS) is a liver-specific growth factor implicated in hepatocellular proliferation and hepatoprotection in models of acute liver injury. In the present study, we examined the effect of exogenous HSS administration on liver proliferating capacity and survival outcome in an experimental animal model of fulminant hepatic failure (FHF) and encephalopathy, induced by repeated injections of thioacetamide (TAA) in rats.

METHODS

Fulminant hepatic failure was induced in adult male Wistar rats by three consecutive intraperitoneal injections of TAA (400 mg/kg of body weight), at 24 h time intervals. The animals received intraperitoneally either a saline solution or HSS (50 mg protein/kg of body weight), 2 h after the second and third TAA injections. The animals were killed at 6, 12 and 18 h post the last injection of TAA.

RESULTS

Levels of liver enzymes and urea in serum, blood ammonia values, liver histology, stage of hepatic encephalopathy and survival were statistically significantly improved in TAA-intoxicated and HSS-treated rats compared to TAA-intoxicated and saline-treated ones. Furthermore, HSS ameliorated liver regenerative indices--DNA biosynthesis, thymidine kinase activity and hepatocyte mitotic activity--in a statistically significant manner.

CONCLUSIONS

Our data suggest the beneficial effect of HSS administration in this animal model of FHF and encephalopathy, supporting evidence for a possible use of HSS as supportive therapy, by increasing hepatocellular proliferation, in management of FHF.

Mitogenic and comitogenic activities of polysaccharides from some European herbaceous plants

From the leaves of Plantago lanceolata, the green parts of Rudbeckia fulgida, the aerial parts of Salvia officinalis and the roots of Valeriana officinalis, crude polysaccharides have been isolated by extraction with water and further purified and fractionated by various techniques. The water-soluble polysaccharides obtained were examined for their immunomodulatory activities using the in vitro mitogenic and comitogenic rat thymocyte tests. The results indicate that in spite of the considerable differences in chemical composition and structural properties, the tested polysaccharides exhibited similar significant immunomodulatory properties with a particularly high adjuvans activity in the case of the Rudbeckia and Salvia polysaccharides. The pectic polysaccharide-rich complex from Valeriana was shown to also stimulate the immune function of bone marrow cells.

Human plasma fibronectin potentiates the mitogenic activity of platelet-derived growth factor and complements its wound healing effects

Integrin-mediated cell adhesion and growth factor stimuli are both required for optimal control of cell proliferation. In the context of skin injury, cell-derived fibronectin and platelet-derived growth factor play important roles in the stimulation of cell proliferation and migration, activities that are crucial to the healing process. To assess the ability of exogenously supplied plasma-derived fibronectin to stimulate wound repair and to study its ability to cooperate with platelet-derived growth factor-BB during healing, we devised a novel topical delivery formulation that allows the controlled release of both molecules to a wound. Using this topical formulation and the rabbit ear model of dermal wound healing, we show that plasma fibronectin is a potent stimulator of the wound healing process. We also show that administration of fibronectin and platelet-derived growth factor-BB in combination has additive wound healing effects. Finally, we report novel findings on the ability of soluble plasma fibronectin to potentiate the mitogenic effects of platelet-derived growth factor-BB in vitro. These findings not only show that optimal concentrations of exogenous fibronectin administered using an effective delivery system stimulate wound healing; they also suggest that PDGF-BB should be administered with fibronectin to achieve optimal therapeutic stimulation of wound healing.

Continuous exposure of mice to superantigenic toxins induces a high-level protracted expansion and an immunological memory in the toxin-reactive CD4+ T cells

We analyzed the responses of several T cell fractions reactive with superantigenic toxins (SAGTs), staphylococcal enterotoxin A (SEA), or Yersinia pseudotuberculosis-derived mitogen (YPM) in mice implanted with mini-osmotic pumps filled with SEA or YPM. In mice implanted with the SEA pump, SEA-reactive Vbeta3(+)CD4(+) T cells exhibited a high-level protracted expansion for 30 days, and SEA-reactive Vbeta11(+)CD4(+) T cells exhibited a low-level protracted expansion. SEA-reactive CD8(+) counterparts exhibited only a transient expansion. A similar difference in T cell expansion was also observed in YPM-reactive T cell fractions in mice implanted with the YPM pump. Vbeta3(+)CD4(+) and Vbeta11(+)CD4(+) T cells from mice implanted with the SEA pump exhibited cell divisions upon in vitro restimulation with SEA and expressed surface phenotypes as memory T cells. CD4(+) T cells from mice implanted with the SEA pump exhibited high IL-4 production upon in vitro restimulation with SEA, which was due to the enhanced capacity of the SEA-reactive CD4(+) T cells to produce IL-4. The findings in the present study indicate that, in mice implanted with a specific SAGT, the level of expansion of the SAGT-reactive CD4(+) T cell fractions varies widely depending on the TCR Vbeta elements expressed and that the reactive CD4(+) T cells acquire a capacity to raise a memory response. CD8(+) T cells are low responders to SAGTs.

Growth and development in rats given recombinant human epidermal growth factor(1-48) as neonates

To assess effects of supraphysiologic doses of human recombinant epidermal growth factor(1-48) (rhEGF(1-48)) on neonatal rats, 10 litters of Wistar rats/treatment group were given 0 (formulated vehicle), 10, 100, or 1000 microg/kg daily by subcutaneous injection on postnatal days (PND) 1 through 6. Clinical signs, body weight, acquisition of developmental landmarks and reflexes, and behavior were monitored during treatment and for 5 weeks thereafter (to PND 42). A subset of animals was euthanized weekly from PND 7-28 and necropsied. Selected tissues were examined microscopically. Body weight gain at 1000 microg/kg during treatment was significantly less than control. Precocious incisor eruption, eye opening, vaginal opening, and preputial separation occurred at 100 and/or 1000 microg/kg. Acquisition of reflexes (negative geotaxis, wire maneuver, acoustic startle reflex, and visual placing) was delayed at 1000 microg/kg. Acquisition of adult locomotion was also delayed at 1000 microg/kg. These effects were transient, as locomotor activity at PND 28 and 42 did not differ from control. Effects on acoustic-startle responding persisted in females to final assessment on PND 42. Habituation to repeated acoustic stimuli was impaired, as well as response inhibition following a prepulse acoustic stimulus. rhEGF(1-48) induced structural changes in the skin, retina, kidney, oral and nasal mucosa, lung, and liver. Many of these changes were consistent with the expected mitogenic activity of rhEGF(1-48) and were transient in nature, as severity and incidence diminished with time. An exception was changes observed in the retina at 1000 microg/kg (rosettes/folds and focal defects in the outer nuclear/photoreceptor layers) that were still present 3 weeks after termination of treatment. Acceleration of developmental landmarks; suppression of reflexes, behavior, and somatic growth; and mitogenic responses in epidermal tissues have been reported in rodents treated with epidermal growth factor (EGF) derived from various mammalian species. These results demonstrate that a 48-amino acid fragment of human EGF produced by recombinant technology also induces such effects.

Effects of 5-fluorouracil on mitogen-induced costimulatory capacity of accessory cells from rat oral mucosa and dental pulp

The present study was designed to investigate the effect of the antimetabolite 5-fluorouracil (5-FU) on the capacity of the oral epithelium and the dental pulp to induce a mitogen-driven T-cell proliferation. Inbred Lewis rats were given 6 i.v. injections of 5-FU (30 mg/kg or 50 mg/kg) over a period of 8 days. Suspensions of oral epithelial and dental pulpal cells were prepared. The costimulatory capacity of the accessory cells from treated animals was monitored by their ability to induce a mitogen (ConA)-mediated proliferation of T cells isolated from regional lymph nodes of untreated animals. Accessory epithelial cells from rats treated with the high dose of 5-FU, but not the low dose, induced a decreased T-cell proliferation compared to controls. Accessory pulpal cells from rats, treated with 30 mg/kg or 50 mg/kg of 5-FU, induced a lower T-cell proliferation. When MHC class II molecule depleted T-cell suspensions from lymph nodes of 5-FU-injected animals were incubated with ConA, a significant proliferative response was observed. This finding correlated with an increase of MHC class II molecule expressing cells detected after incubation, although no such cells were observed immediately following the initial purification step of T cells. This finding demonstrates that the accessory cells could partly restore their expression of MHC class II molecules during incubation. The results of the study suggest that the function of immunocompetent cells of the oral mucosa and dental pulp is influenced by treatment with 5-FU and that the function of accessory cells of the pulp is affected more than the function of accessory cells derived from the oral mucosa.

Flow cytometric quantitation of calcium-dependent and -independent mitogen-stimulation of T cell functions in whole blood: inhibition by immunosuppressive drugs in vitro

We have optimized assays to measure mitogen-stimulated rat lymphocyte activation in whole blood and have used these assays to quantitate the potencies of immunosuppressive drugs with different mechanisms of action. To define the optimal conditions for measuring T cell functions in whole blood, the effects of different concentrations of mitogens that activate T cells through calcium-dependent and -independent pathways were measured over time. Proliferation was measured by tritium-labeled thymidine ([3H]-TdR) incorporation and by flow cytometric analysis of proliferating cell nuclear antigen (PCNA)/DNA content. Furthermore, we detected the increases in percent expression of cell-surface activation antigens (CD25, CD134, CD71, CD11a and CD54). Concanavalin A (Con A) stimulated maximum lymphocyte proliferation and expression of T cell surface activations by 72-96 h, which was 48 h later than stimulation by phorbol 12-myristate 13-acetate (PMA) plus anti-CD28 monoclonal antibody (mAb) or PMA plus ionomycin (IONO). Addition of sirolimus, tacrolimus, cyclosporine or the active metabolite of leflunomide, A77 1726, to mitogen-stimulated whole blood produced drug concentration-dependent inhibitions of lymphocyte proliferation and expression of cell surface activation antigen expression. From these data, we determined drug potencies (inhibitory concentration of 50%, IC(50)) and drug concentrations causing maximum inhibition of T cell functions (I(max)). We developed simple and reproducible assays to measure different lymphocyte functions in whole blood cultures. These assays were used to investigate the mechanisms of different immunosuppressive drugs. These methods can be exploited to measure T cell functions in blood collected from subjects treated with immunosuppressants in vivo.

Covalently conjugated VEGF--fibrin matrices for endothelialization

Vascular endothelial growth factor (VEGF) is a key factor in endothelial cell biology and blood vessel formation and a candidate therapeutic for the stimulation of angiogenesis-dependent tissue regeneration. The objective of this study was to confer the angiogenic activity of VEGF(121) upon the biomaterial fibrin, a natural substrate for endothelial cell growth and clinically accepted as 'fibrin glue'. To achieve this, we engineered fibrin-based hydrogels that were covalently modified with VEGF(121). Our laboratory has recently developed novel methodology that allows the covalent incorporation of exogenous bioactive peptides by the transglutaminase activity of factor XIIIa into fibrin during coagulation. Here, this ability of factor XIIIa to crosslink additional proteins within fibrin was employed to covalently incorporate VEGF(121). By recombinant DNA methodology, a mutant VEGF(121) variant, alpha(2)-PI(1--8)-VEGF(121), which contains an additional factor XIIIa substrate sequence NQEQVSPL at the aminoterminus, was expressed in E. coli. In soluble form, the mutant protein fully retained its mitogenic activity for endothelial cells. Using (125)I-labeled alpha(2)-PI(1--8)-VEGF(121), its covalent incorporation and the efficiency of incorporation into fibrin was demonstrated and characterized. The immobilized, fibrin-conjugated VEGF(121) protein remained an active and very efficient mitogen for human endothelial cells grown on two-dimensional VEGF(121)-modified fibrin surfaces, and the incorporation of increasing amounts of alpha(2)-PI(1--8)-VEGF(121) resulted in dose-dependent enhancement of endothelial cell growth. The VEGF-modified fibrin matrices can be formed as injectable gels in a single-step reaction under physiological conditions in vivo. When used as a ingrowth matrix, such VEGF incorporating materials could be useful in a variety of clinical situations that require an angiogenic response into an ischemic region or inplant.

26S proteasome inhibition induces apoptosis and limits growth of human pancreatic cancer

The 26S proteasome degrades proteins that regulate transcription factor activation, cell cycle progression, and apoptosis. In cancer, this may allow for uncontrolled cell division, promoting tumor growth, and spread. We examined whether selective inhibition of the 26S proteasome with PS-341, a dipeptide boronic acid analogue, would block proliferation and induce apoptosis in human pancreatic cancer. Proteasome inhibition significantly blocked mitogen (FCS) induced proliferation of BxPC3 human pancreatic cancer cells in vitro, while arresting cell cycle progression and inducing apoptosis by 24 h. Accumulation of p21(Cip1-Waf-1), a cyclin dependent kinase (CDK) inhibitor normally degraded by the 26S proteasome, occurred by 3 h and correlated with cell cycle arrest. When BxPC3 pancreatic cancer xenografts were established in athymic nu/nu mice, weekly administration of 1 mg/kg PS-341 significantly inhibited tumor growth. Both cellular apoptosis and p21(Cip1-Waf-1) protein levels were increased in PS-341 treated xenografts. Inhibition of tumor xenograft growth was greatest (89%) when PS-341 was combined with the tumoricidal agent CPT-11. Combined CPT-11/PS-341 therapy, but not single agent therapy, yielded highly apoptotic tumors, significantly inhibited tumor cell proliferation, and blocked NF-kappaB activation indicating this systemic therapy was effective at the cancer cell level. 26S proteasome inhibition may represent a new therapeutic approach against this highly resistant and lethal malignancy.

Systemic proliferative changes and clinical signs in cynomolgus monkeys administered a recombinant derivative of human epidermal growth factor

Epidermal growth factor (EGF) effects have been explored extensively in vivo in rodents, but little is known about trophic responses in nonhuman primates. A previous publication reports the hyperplastic epithelial/parenchymal changes noted in the digestive tract (tongue, esophagus, stomach, intestine, liver, gallbladder, pancreas, and salivary glands) of adult cynomolgus monkeys treated with recombinant human EGF(1-48) (rhEGF(1-48)). This report documents clinical findings and structural effects in the remaining epithelium-containing tissues of these animals. Two monkeys/sex/dose received rhEGF(1-48) by intravenous bolus at 0 (vehicle), 10, 100, 500 (females only), or 1,000 microg/kg/day (males only) daily for up to 2 weeks. Treatment- and dose-related clinical findings included emesis, fecal alterations (soft feces and diarrhea), lacrimation, nasal discharge, hypoactivity, transient hypotension, and salivation after dosing. Male monkeys administered 1,000 microg/kg became moribund after 5 days of treatment and were necropsied. All other monkeys completed the 2-week treatment period. Necropsy findings in nongastrointestinal tissues were: enlarged, pale kidneys at 100 microg/kg and greater; small thymuses seen sporadically at all doses; and enlarged adrenals and small thyroids in males at 1,000 microqg/kg. Respective organ-to-brain weight ratios at 500 and 1,000 microg/kg for kidneys were 1.5- and 2.6-fold greater and for heart were 1.7- and 1.3-fold greater than controls. Microscopically, pronounced dose-related epithelial hypertrophy and hyperplasia were evident in kidney, urinary bladder, skin (epidermis and adnexa), mammary gland, prostate, seminal vesicles, epididymis, uterus, cervix, vagina, thyroid, thymus, tonsillar crypts, cornea, trachea, and pulmonary airways. Epitheliotrophic effects were conspicuous in many tissues at 100 to 1,000 microg/kg. Changes to renal collecting ducts were present at 10 microg/kg, suggesting that kidneys were a relatively sensitive target. Proliferative alterations were not apparent in testes, intraocular structures, brain ependyma and choroid plexus at any dose. Aside from the noted exceptions, rhEGF(1-48) was a pantrophic epithelial mitogen in cynomolgus monkeys when used intravenously at suprapharmacologic doses.

Lymphocyte proliferation is possible with low concentrations of glycyl-glutamine

The positive effect of glutamine on lymphocyte proliferation has previously been described. Its dipeptide glycyl-glutamine (GlyGln) is more stable than pure glutamine in aqueous solutions. The aim of our study was to investigate the relationship between lymphocyte proliferation and varying concentrations of glycyl-glutamine in vitro. Isolated human lymphocytes were stimulated with the mitogens phytohaemagglutinin (PHA), Concanavalin A (ConA), pokeweed mitogen (PWM), and Staphylococcus aureus (SAC). Glycyl-glutamine was added to yield final concentrations of 0-2 mmol/l. Overall, minimal concentrations of 0.01 mmol/l glycyl-glutamine were sufficient to enhance lymphocyte proliferation over baseline (glutamine-free) levels. No difference was found between concentrations in the "physiological" range of 0.4 mmol/l and very low concentrations (0.04-0.1 mmol/l) with SAC, ConA and PWM. Increasing the concentration beyond 0.4 mmol/l (up to 2.0 mmol/l) offered further gain with PHA-stimulation only. Lymphocyte proliferation under in vitro polyclonal stimulation is maintained even at very low concentrations of glycyl-glutamine. Raising the concentration above the equivalent of physiological levels does not seem to provide further benefit.

Intravenous administration of stabilized antisense lipid particles (SALP) leads to activation and expansion of liver natural killer cells

Stabilized antisense lipid particles (SALP) have been developed for the systemic delivery of oligonucleotides. The impact of intravenous SALP administration was measured with respect to activation of natural killer (NK) and NK1.1+ T (NKT) cells in the livers of immunocompetent mice. Treatment with a SALP containing a highly mitogenic oligonucleotide (INX-6295) generated an increase in NK cytolytic activity and cell number within the liver but did not appear to affect the number of hepatic NKT cells or their cytolytic activity. The same results were observed after intravenous administration of the mitogenic oligonucleotide alone. Interestingly, treatment with a SALP containing a weakly mitogenic oligonucleotide (INX-6300) also activated the liver NK cells, whereas the oligonucleotide alone was unable to elicit these effects. The NK stimulatory activity of a SALP containing INX-6300 required both lipid and oligonucleotide components. These results demonstrate that in addition to modifying the pharmacokinetics and biodistribution of intravenously administered oligonucleotides, SALP possess immunostimulatory activity independent of oligonucleotide mitogenicity, which can serve as an adjuvant to antisense therapies for cancer.

Expression of interleukin 1 alpha and beta, and interleukin 1 receptor antagonist mRNA in the rat central nervous system after peripheral administration of lipopolysaccharides

Interleukin 1alpha (IL-1alpha) and IL-1beta, and the endogenous IL-1 receptor antagonist (IL-1ra) are known members of the IL-1 family. Using in situ hybridization histochemistry we demonstrated that following endotoxin injection (lipopolysaccharides, LPS, 2.0 mg/kg, i.p.) a time dependent expression and partly different expression patterns of the cytokines occurred within the rat brain and pituitary gland. All cytokines were observed in the choroid plexus. In addition, IL-1ra mRNA expressing cells were observed scattered in the brain parenchyma, whereas scattered IL-1beta mRNA expressing cells were restricted to central thalamic nuclei, the dorsal hypothalamus, and cortical regions, such as the parietal and frontal cortex. A strong IL-1beta mRNA expression was found in the circumventricular organs. In the pituitary gland, a low IL-1alpha and a high IL-1beta mRNA expression was observed, with the highest density of cytokine-expressing cells seen in the posterior pituitary. The cell types expressing the mRNA's of IL-1alpha, IL-1beta and IL-1ra were identified as monocytes in the circumventricular organs and the pituitary gland, and as microglia in the brain parenchyma. In conclusion, the present findings revealed that cytokine production in response to a peripheral endotoxin challenge mainly occurs in peripherally derived monocytes in the circumventricular organs and the pituitary gland. IL-1beta is the predominant form expressed, whereas the expression of IL-1alpha mRNA and IL-1ra mRNA is lower. Our observations support the view that peripherally derived IL-1 may play a role in the induction of centrally mediated illness symptoms.

Subchronic administration of phenobarbital alters the mutation spectrum of lacI in the livers of Big Blue transgenic mice

Phenobarbital (PHE) is a liver carcinogen in B6C3F1 mice and a weak mutagen that does not appear to form DNA adducts. To investigate PHE mutagenicity in vivo, B6C3F1 Big Blue(R) male transgenic mice harboring the lambdaLIZ shuttle vector containing the lacI target gene were fed PHE at 2500 ppm for 180 days. A modest increase in the mutant frequency (MF) from 5.02+/-2.4x10(-5) in the control group to 6.88+/-0.754x10(-5) in the PHE-treated group, which was marginally different (p<0.05), was obtained. To better assess the relevance of this increase in MF, a random collection of mutants from each PHE-exposed mouse was sequenced. After correcting for clonal expansion, which is the most conservative approach, the MF in the PHE-treated mice decreased to 6.39+/-1.02x10(-5), an insignificant difference (p=0.10) from that in control group. Despite this modest increase in MF, the mutation spectrum obtained from the PHE-exposed group was significantly different (pA:T transitions remained the same in the two spectra. It is postulated that the increase in transversions at G:C base pairs found in the PHE-derived spectrum is likely due to oxidative damage as a result of induction of CYP2B isozymes by the chronic administration of PHE. Results from this study demonstrate that PHE alters the spectrum of mutations, rather than inducing a significant global increase in the MF. The PHE-derived spectrum of lacI mutants from the liver of Big Blue(R) B6C3F1 male mice was remarkably similar (p=0.8) to that generated by oxazepam (OX), a compound which also induces CYP2B isozymes following chronic administration of the drug.

Insulin-like growth factor-1 receptors mediate infragenicular vascular smooth muscle cell proliferation in response to glucose and insulin not by insulin receptors

PURPOSE

Vascular smooth muscle cell (VSMC) proliferation is an early event in the pathogenesis of atherosclerosis. Insulin and glucose are known to stimulate the growth of VSMC. Cell membrane receptors play an important role in the proliferation of VSMC in response to growth factors. Insulin and insulin-like growth factor-1 (IGF-1) have demonstrated a cross reactivity for receptor binding and function. By using monoclonal antibodies directed against insulin (IRA) and IGF-1 (IGF-1RA) receptors, we attempt to further delineate the mechanism for the proliferation of VSMC in response to insulin and glucose.

METHODS

Human infragenicular VSMC isolated from diabetic patients undergoing below-knee amputations were used. Cells from passages 3 to 6 were grown in serum-free media with a glucose concentrations of 0.1% or 0.2%, both with and without insulin (100 ng/mL). The baseline cell density was 4,635 +/- 329 cells/mL. IRA or IGF-1RA was added to the media, with the control group receiving neither antibody. Cells were grown in 5% CO2 at 37 degrees C for 6 days. Analysis of variance was used for statistical analysis, with P <0.05 considered significant. In addition, DNA synthesis was measured using thymidine incorporation assays in the same groups of cells receiving IRA, IGF-1RA, and no antibody.

RESULTS

IGF-1RA prevented the proliferation of VSMC in response to insulin and glucose, while IRA had no effect on cell growth. There was no significant growth when IGF-1RA was added to the media, while the control group and the group receiving IRA demonstrated significant growth compared with the baseline concentration of 4,635 +/- 329 cells/mL at all concentrations of insulin and glucose. [3H]thymidine incorporation assays confirmed the cell count results.

CONCLUSIONS

These results suggest that the mitogenic effects of insulin and glucose on infragenicular VSMC are due to stimulation of the IGF-1 receptor. VSMC antiproliferative strategies employing receptor blockade should be directed against the IGF-1 receptor, not the insulin receptor.

Kinetic and immunohistochemical characteristics of mitogen-induced cutaneous hypersensitivity in chickens selected for antibody responsiveness

Mitogen-induced cutaneous hypersensitivity was evaluated in chickens selected for high and low antibody responses to SRBC, and in a random bred control line. Wing web swelling responses were found after subcutaneous administration of phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), and Escherichia coli lipopolysaccharide (LPS), respectively, in all three lines. All mitogens induced significant acute 4 h wing web swelling responses, followed by a significant (classical) late 24 h wing web swelling response. The 4 h responses were significantly lower in the L line, whereas a tendency for lower responses at 24 h in the L line was found as well. Immunohistochemical evaluation of the early and late wing web swelling responses revealed extravascular localisation of leukocytes at 24 h after sensitization with mitogens, which consisted of CD4+ cells, CD8+ cells, TCR-1+ cells, and heterophils, but no B cells, whereas the 4 h swelling response was primarily characterized by oedema. Cutaneous hypersensitivity either initiated by T-cell mitogens as well as B-cell mitogens may depend for an important part on the rapid induction of local homing of lymphocytes towards the sensitizing agent, which may be mediated by an acute local expression of molecules with chemo-attractive capacities. Interpretation of cellular immunity responses in vivo such as delayed-type hypersensitivity should therefore incorporate oedema-initiating characteristics of sensitizing agents. The relationship between the magnitude of cutaneous hypersensitivity to mitogens and selection for antibody responsiveness is discussed.

The effects of platelet-derived growth factor-BB on healing of the rabbit medial collateral ligament. An in vivo study

We report a biologic approach to improve medial collateral ligament healing using growth factors normally expressed in healing tissue. Our previous in vitro work demonstrated that platelet-derived growth factor-BB and transforming growth factor-beta 1 promoted fibroblast proliferation and matrix synthesis, respectively. There-fore, these growth factors were used in vivo to determine whether they could improve medial collateral ligament healing, whether this effect was dose-dependent, and if combinations of growth factors could improve healing more than individual growth factors. Thirty-seven rabbits had various doses of growth factors applied to the ruptured right medial collateral ligaments using a fibrin sealant delivery vehicle. The five groups consisted of 1) two groups receiving two doses of platelet-derived growth factor-BB, 2) two groups receiving two doses of this growth factor plus transforming growth factor-beta 1, and 3) one group receiving fibrin sealant only. After sacrifice at 6 weeks, biomechanical and histologic evaluations of the healing ligament were performed. Femur-medial collateral ligament-tibia complexes of the knees given the higher dose of platelet-derived growth factor-BB had ultimate load, energy absorbed to failure, and ultimate elongation values that were 1.6, 2.4, and 1.6 times greater than the same complexes of the control group. Adding transforming growth factor-beta 1 did not lead to any further increase in the structural properties of the complex compared with treatment with platelet-derived growth factor-BB. These encouraging results suggest that use of platelet-derived growth factor-BB may improve the quality of the healing medial collateral ligament, and that it may also have a similar potential for promoting healing of other ligaments.

Stimulation of human smooth muscle cell proliferation by thrombin involves increased synthesis of platelet-derived growth factor

OBJECTIVES

Thrombin generated at sites of vascular injury not only participates in the coagulation cascade but can also signal other events related to cell mitogenesis and migration. In this report, we investigated the effects of thrombin on the proliferation of human arterial smooth muscle cells (SMCs) in culture and its interaction with platelet-derived growth factor (PDGF).

MATERIAL AND METHODS

Human arterial SMCs originated from a renal artery were grown in cell culture. The effect of thrombin on DNA synthesis was evaluated by 3H-thymidine incorporation. The effect of thrombin on inositol-phosphate formation by SMCs was also analyzed as well as the binding of PDGF AA and BB to these cells. PDGF secretion was analyzed by radioimmunoassay (RIA).

RESULTS

Exposure of cultured human SMCs to thrombin caused an increased rate of DNA synthesis in a dose-response manner, with a maximal stimulatory effect at a concentration of 2.0 U/mL. Thrombin was found to increase the accumulation of inositol phosphates and to increase the production of PDGF as measured by RIA. Exposure of cells to 2.0 U/mL thrombin resulted in a strong decrease in PDGF AA binding to PDGF receptors and did not change PDGF BB binding, probably indicating that PDGF alpha-receptors could be occupied by endogenously produced PDGF A.

CONCLUSION

Thrombin stimulates human vascular SMC proliferation in a dose-response way, in part by the formation of inositol phosphates. The mechanism responsible for this effect involves, at least in part, an increased endogenous synthesis of PDGF.

Effects of basic fibroblast growth factor on human periodontal ligament cells

In order to clarify the regulatory mechanisms of periodontal regeneration by basic fibroblast growth factor (bFGF), effects of bFGF on proliferation, alkaline phosphatase activity, calcified nodule formation and extracellular matrix synthesis of human periodontal ligament (PDL) cells were examined in this study. bFGF enhanced the proliferative responses of PDL cells in a dose-dependent manner. The maximum mitogenic effect of bFGF on PDL cells was observed at the concentration of 10 ng/ml. In contrast, bFGF inhibited the induction of alkaline phosphatase activity and the mineralized nodule formation by PDL cells. Moreover, employing the reverse transcription-polymerase chain reaction (RT-PCR) technique, we observed that the levels of laminin mRNA of human PDL cells was specifically upregulated by bFGF stimulation, but that of type I collagen mRNA was downregulated. On the other hand, the expression of type III collagen and fibronectin mRNA were not altered even when the cells were activated by bFGF. These results suggest that suppressing cytodifferentiation of PDL cells into mineralized tissue forming cells, bFGF may play a role in wound healing by inducing growth of immature PDL cells and that in turn accelerates periodontal regeneration.

The effect of alpha-adrenergic antagonism upon nitrogen loss during endotoxemia

Sixty male Sprague-Dawley rats were randomized to receive parenteral nutrition (PN) only; PN plus continuous infusion of Escherichia coli 026:B6 lipopolysaccharide (PN + LPS) at 6 mg.kg-1.d-1; or PN plus LPS plus a continuous infusion of the alpha-adrenergic antagonist phentolamine (PN + LPS + PHEN) at 5 mg.kg-1.d-1 or 20 mg.kg-1.d-1 for 48 h. All animals received isocaloric, isonitrogenous PN. LPS significantly lowered nitrogen balance (mmol/48 h) from PN control; however, addition of PHEN substantially worsened nitrogen balance compared with LPS (14.2 +/- 3, 2.4 +/- 5.2, -1.6 +/- 4.5, -0.8 +/- 5.4, for the PN, PN + LPS, PN + LPS + PHEN5 and PN + LPS + PHEN20 groups, respectively; P < 0.0001). Urinary 3-methylhistidine/creatinine ratio (3-meH/creat) paralleled the nitrogen balance data (0.30 +/- 0.09, 0.45 +/- 0.12, 0.51 +/- 0.14, 0.60 +/- 0.12, respectively; P < 0.0001). The high-dose PHEN resulted in 82 +/- 9% blockade. To ascertain if any beneficial effect upon body protein loss is achieved during severe stress, 30 rats were given PN + LPS at 12 mg.kg-1.d-1 or PN + LPS12 + PHEN20. These data showed similar changes in nitrogen balance and 3-methylhistidine/creatinine with the use of PHEN during severe endotoxemia. alpha-adrenergic antagonism with PHEN worsens body protein loss as measured by nitrogen balance and 3-methylhistidine/creatinine in PN-fed endotoxemic rats.

Major histocompatibility complex class II region confers susceptibility to Staphylococcus aureus arthritis

The importance of the MHC class II region for the development of septic arthritis was studied in a murine model of haematogenously induced Staphylococcus aureus arthritis. In the first experiment MHC class II deficient mice (A beta-/-) and their heterozygous (A beta+/-) littermates were intravenously inoculated with a single dose of toxic shock syndrome toxin-1 producing S. aureus LS-1 strain. The results demonstrate that the expression of class II MHC molecules increases the prevalence and severity of arthritis. To analyse the impact of MHC class II haplotypes on the disease onset and progression the authors used congenic C3H.NB, C3H.Q and C3H/HeJ mice in the second set of experiments. The results show that C3H/HeJ mice developed the highest frequency and the most severe course of arthritis compared with C3H.NB and C3H.Q animals. Immunohistochemical analysis of arthritic joints revealed equal number of macrophages, CD4+ and CD8+ lymphocytes in the inflamed synovia in all the congenic mice. In contrast, the number of MHC class II expressing cells was higher in the arthritic joints of C3H/HeJ mice compared with the congenic strains (P < 0.001). Furthermore, serum levels of proarthrtitogenic cytokines, such as tumour necrosis factor and interleukin-6 were higher in C3H/HeJ group. This study indicates that MHC class II expression is necessary for the development of S. aureus arthritis in mice and that different MHC class II haplotypes confer varying susceptibility for development of joint inflammation induced by staphylococci.

Ethanol enhances the mitogen-driven lymphocyte proliferation in patients with psoriasis

Ethanol has been reported to exacerbate psoriasis. Since immunological mechanisms are considered to be important for the pathogenesis of psoriasis, we compared the effects of ethanol on lymphocyte proliferation in 15 healthy control individuals and 15 patients with psoriasis. We employed the spontaneous and phytohemagglutin in (PHA)-induced uptake of 3H-TdR to measure lymphocyte proliferation. Ethanol was added to cultures at concentrations ranging from 0.5 to 0.0005% (vol./vol.). We found that both spontaneous and PHA-driven lymphocyte proliferations were significantly lower in patients with psoriasis (P < 0.002). Spontaneous blastogenesis in both controls and patients remained stable under ethanol. In controls, ethanol suppressed the PHA-driven lymphocyte proliferation in a dose-dependent fashion. By contrast, in patients with psoriasis ethanol significantly increased lymphocyte proliferation by 2-3 times (p < 0.002). Our data indicate that in psoriasis the lower lymphocyte transformation is abnormally enhanced by minimal doses of ethanol.

Additive effects of extra cellular matrix proteins and platelet derived mitogens on human retinal pigment epithelial cell proliferation and contraction

PURPOSE

In proliferative vitreoretinopathy (PVR) retinal pigment epithelial cells (RPE) cells are thought to synthesize and interact with extracellular matrix (ECM) proteins to form fibrocellular membranes attached to the retina, which the cells then progressively contract detaching the retina. Haemorrhage into the eye is an exacerbating factor in the pathology. To investigate some of the possible interactions between ECM proteins, platelet mitogens and RPE cells in this study, we examined the combined effect of platelet derived mitogens and ECM proteins on RPE cell proliferation and contraction.

METHODS

Cells were cultured on a range of individual ECM proteins as well as on the ECM deposited by normal vitreous fluid and exposed to platelet mitogens. Effects on cell proliferation and cell detachment from these substrates and tissue culture plastic were examined.

RESULTS

We report additive/synergistic effects of platelet mitogens (PDGF and TGFb1) as well as bFGF, with ECM proteins (laminin, fibronectin, collagen 1 and vitreous-deposited ECM) on RPE proliferation. Further we report stimulation of RPE cell contraction on vitreous proteins when exposed to serum prepared from platelet-rich plasma. In this context it was noticeable that it was cells grown on vitreous matrix plus pigment rather than cells grown on clear vitreous that exhibited this behaviour.

CONCLUSIONS

This study supports a combined action of platelet mitogens and matrix proteins in inducing RPE cell proliferation and contractility and provides a simple in vitro model of some of the late stages of PVR.

Lysates from cultured allogeneic keratinocytes stimulate wound healing after tympanoplasty

In the past, cultured keratinocyte allografts have been used with benefit in the treatment of burn wounds and leg ulcers. Since in burn wounds autologous and allogeneic fresh keratinocyte cultures were found to give similar favorable results as lysates of allogeneic cultured cells, the authors investigated whether this lysate mixed in an antibiotic suspension would also accelerate the epithelial healing after routine tympanoplasty. In a double blind setting the healing process in 50 consecutive tympanoplasty ears was studied: an acceleration of healing of 8 days was observed in the lysate-treated group (39.25 days) as compared with the control group (47.23 days). The percentage of ears which healed within 6 weeks (after 5 weekly applications of 200 microliters suspension in both groups) was significantly higher in the treated group (61%) than in the control population (36%). Although the therapeutical effect of the keratinocyte lysate in this study is believed to be due primarily to its mitogenic activity through growth factors or cytokines, at present it is still unclear which growth factors are involved and which combinations of these factors have to be present to modulate the different stages of the complex healing processes.

Effect of interleukin-2 and interleukin-4 on lymphocytes from peribronchial lymphatic tissue

Lymphocyte activation in spleen and peribronchial lymphatic tissue (PBLT) following stimulation with T-cell mitogens and lymphokines was investigated in the hamster. Optimal mitogen-induced cell proliferation was achieved after culturing for 6 days in vitro. Interleukin-2 (IL-2) and interleukin-4 (IL-4) did not induce DNA synthesis in resting T-cells from either spleen or PBLT.IL-2 or IL-4 in combination with concanavalin A promoted splenic T-cell proliferation. In contrast, in PBLT, IL-2-but not IL-4-enhanced cell proliferation (p < .001). The findings indicate that PBLT represents an independent compartment of the immune system. Furthermore, in the hamster PBLT cells consist predominantly of IL-2-responsive cells, i.e., are of the Th1 type. Immunological pathogenesis of lung injury can therefore be studied by functional analysis of PBLT lymphocytes.

Choline phosphate and phorbol ester potentiate the mitogenic effect of insulin by competitive mechanisms in NIH 3T3 fibroblasts

Treatments of serum-starved NIH 3T3 fibroblasts with either 100 nM phorbol-12-myristate 13-acetate (PMA) or 1 mM choline phosphate (ChoP) greatly enhanced, in a mutually inhibitory manner, the stimulatory effect of insulin on DNA synthesis. Wortmannin and GF 109203X, inhibitors of phosphatidylinositol 3'-kinase and protein kinase C, respectively, inhibited only the combined mitogenic effects of PMA and insulin, but not that of ChoP and insulin. In the presence of 0.5% fetal calf serum, both ChoP and insulin, but not PMA, retained their mitogenic activities, while PMA abolished the stimulatory effect of insulin on DNA synthesis. The results indicate that PMA can both enhance and inhibit the mitogenic action of insulin, depending on the presence of serum factors and ChoP.

Aluminum potentiates the effect of fluoride on tyrosine phosphorylation and osteoblast replication in vitro and bone mass in vivo

Osteosclerosis in workers exposed to fluoride (F) and aluminum (Al) (industrial fluorosis) led to the use of F as a treatment to increase bone mass in osteoporosis patients. Because the influence of traces of Al on the effects of F on bone formation is heretofore unknown, we have investigated this issue both in vitro and in vivo. We have found that minute amounts of Al (< or = 10(-5) M) potentiate the effects of F in vitro such that osteoblast proliferation increased by 15 +/- 2.7% at 50 microM (p < 0.001) and by 117.6 +/- 5.1% at 750 microM (p < 0.001), concentrations of F with no mitogenic effect alone. F + Al time-dependently modulated a growth factor signaling pathway(s) associated with enhanced tyrosine phosphorylation (TyrP) of several proteins (p90 [2.9x], p77 [4.9x], p68 [9.6x], and mitogen activated protein kinases [3x]). TyrP was only slightly or not at all changed by F and Al alone, respectively. The effects of F + Al on TyrP and cell proliferation were markedly reduced by 100 microM tyrphostin-51, a tyrosine kinase inhibitor. Protein kinase A (PKA) and protein kinase C (PKC) pathways were not involved in this response. In vivo, F + Al administered for 8 months, at doses that had no effect when the minerals were administered individually, significantly enhanced proximal tibia bone mineral density (BMD) by 6.3 +/- 1% compared with initial values and by 2-fold compared with control ovariectomized rats (p < 0.0001). These effects are consistent with a crucial role of Al in osteosclerosis observed in industrial fluorosis. The results suggest that the combination of F + Al modulates a growth factor-dependent TyrP pathway enhancing mitogen-activated protein kinase and osteoblastic proliferation and bone mass.

Low- and high-density lipoproteins as mitogenic factors for vascular smooth muscle cells: individual, additive and synergistic effects

The mitogenic activities of low (LDL)- and high (HDL)-density lipoproteins have been examined in cultures of human vascular smooth muscle cells (VSMC). LDL and HDL3 dose-dependently (EC50 values approximately 50 micrograms/ml) stimulated DNA and protein synthesis ([3H]-thymidine and [3H]-leucine incorporation, respectively) in the absence of exogenously added mitogens. The synthetic responses of VSMC to combinations of LDL and HDL3 were additive, indicating that each lipoprotein mediates discrete effects. LDL or HDL3 promoted VSMC proliferation under strict mitogen-free conditions, but this growth response was not sustained. VSMC exposed to combinations of lipoproteins (either LDL or HDL3) and growth factors (either PDGF-BB, EGF, bFGF or IGF) exhibited synergistic DNA synthesis responses. In the combined presence of PDGF-BB and either LDL or HDL3, VSMC proliferation was sustained. Anionized lipoprotein preparations (oxidized, acetylated, carbamylated or malonimylated) also stimulated DNA and protein synthesis. Since the antioxidant beta-hydroxylated toluene did not block the effect of native LDL on DNA synthesis, and fucoidin, a specific competitor for the 'scavenger' receptor, did not inhibit oxidized LDL-induced DNA synthesis, activation of mitogenic signals by lipoproteins does not depend on lipid peroxidation. Rather, the apparent intrinsic mitogenic potential of lipoproteins may depend upon their direct activation of replication-coupled signal transduction systems.

Effect of bolesatine on phospholipid/calcium dependent protein kinase in Vero cells and in rat thymus

Bolesatine, a glycoprotein from Boletus satanas Lenz, has previously been shown to be mitogenic to rat and human lymphocytes at very low concentrations, whereas higher concentrations inhibit protein synthesis in vitro and in several in vivo systems. The mechanism whereby this mitogenic activity occurs was previously unknown. To elucidate this mechanism, the effects of bolesatine have been studied in a cell-free system, VERO cells, and in vivo in rat thymus. In a cell-free system, bolesatine appears to be a direct effector of PKC. The activation is concentration dependent for 1-10 ng/ml. At the same time, VERO cells significantly proliferate when incubated with the bolesatine (3, 5 and 10 ng/ml), since the DNA synthesis increases by 27, 48, and 59%, for respectively, 3, 5 and 10 ng/ml compared with control. Moreover, Bolesatine (5 and 10 ng/ml) induces InsP3 release in a concentration-dependent manner (114 and 142%) as compared to control. In vivo, 24 h after oral administration of bolesatine to rates (20, 100 and 200 microg/kg), PKC activity is significantly increased in thymus. THe most effective doses (100 and 200 microg/kg) give 590-620% increase in cytosolic PKC activity and 85-91% increase in total PKC activity as compared to control. This PKC activation by bolesatine in rat thymus is directly linked to the mitogenic activity observed in vivo. Bolesatine is thus capable of activating the PKC directly and/or indirectly (via InsP3 release) during its mitogenic processes.

Blastogenesis and interleukin-2 receptor expression assays in the harbor seal (Phoca vitulina)

Two in vitro functional assays were developed to evaluate mitogen-induced responses of peripheral blood mononuclear leukocytes (PBML) from free-ranging harbor seals, Phoca vitulina. Lymphocyte proliferation was measured by a standard blastogenesis assay following optimization of culture conditions including mitogen concentration, cell density, and incubation time. These optimized parameters, with the exception of incubation time, were subsequently employed to measure lymphocyte activation by analytical flow cytometry using fluorochrome-based identification of cell surface interleukin-2 receptor (IL-2r) expression. Baseline values established for free-ranging harbor seals had extensive animal variability; there was evidence that the samples were derived from a group of animals with a normal distribution. Positive correlations were observed between blastogenesis assays, and between blastogenesis and activation assays, when using pokeweed or concanavalin A as the stimulus. However, no relationship was found in the expression of the IL-2r induced by these mitogens. This result supports the contention that the two mitogens stimulate different lymphocyte subpopulations. This was observed only with the IL-2r expression assay because of its unique ability to measure the number of T lymphocytes initially activated rather than the ultimate number of progeny cells identified by blastogenesis. Both assays, used concurrently, should provide a more comprehensive representation of lymphocyte competence and serve as a measure of animal health.