Influence of geography, seasons and pedology on chemical composition and anti-inflammatory activities of essential oils from Lippia multiflora Mold leaves

ETHNOPHARMACOLOGICAL RELEVANCE

Lippia multiflora is a plant with nutritional and pharmaco-therapeutic properties that is native to central and occidental Africa. The potential effects of plants on health are associated with their chemical composition. Therefore, the present study aimed to identify chemical variations in essential oils of Lippia multiflora as a function of geographic origin and time of annual harvest to determine optimal chemical profiles for ethno-pharmacotherapeutic applications.

MATERIALS AND METHODS

Experimental plants were cultivated at Abidjan (LPA), Toumodi (LPT) and Bondoukou (LPB). Natural Lippia multiflora seeds were sourced to produce standardized plants over a period of six months. Standard plants (n=40) were re-introduced into natural plots, cultivated for 12 months and leaves were sampled monthly in a standardized fashion. Essentials oils (n=36) were then extracted from these samples by hydro-distillation according to the European Pharmacopoeia and qualitatively and quantitatively analyzed using GC/FID and GC/MS. These data were then analyzed using Principal Component Analysis (PCA). Anti-inflammatory properties were also assessed against activated macrophages in vitro.

RESULTS

The results indicated that chemical profiles and essential oil yields vary according to the location where the plants were cultivated. One essential oil chemotype corresponded to the LPA and LPT sites and one corresponded to the LPB site. Statistical analysis of the chemical profiles and monthly evolution of the three sites over a period of one year allowed assessment of variations in composition and the subsequent choice of the optimal harvest time for ethnopharmacological applications. Anti-inflammatory activity apparently correlated with chemical profiles of essential oils and the geographic origins of the plants.

CONCLUSION

The optimal harvest time was associated with the maximum yield of pharmacological compounds with the most potential interest for health.

A contribution to the understanding of micro-pollutant sorption mechanisms in wastewater biological processes: case of the tributyltin

Micro-pollutant fluxes distribution throughout the physical separation and biological units of wastewater treatment plants (WWTPs) are very dependent ofsorption phenomena. The understanding and the control of the sorption stage is thus essential for the optimization of micro-pollutant removal in WWTPs, and particularly in biological treatments where these mechanisms influence the bioavailability towards micro-organisms. If the influence of the micro-pollutant physicochemical characteristics (e.g. Kow, pKa) on their ability to sorb on biological media (i.e. sludge) has been demonstrated, it appears that some other parameters, like the biosorbent characteristics, have to been taken into account. The aim of this study is thus to correlate the capacities of sorption of an environmentally relevant substance (tributyltin), with a thorough characterization of different types of sludge. The characterization of three biological media (raw, sonicated and flocculated activated sludges) is proposed according to various characterization parameters related to biochemical composition, aggregate size, rheological behaviour etc. The results show first that, whatever the sludge characteristics may be, the sorption mechanisms are very rapid and that an equilibrium state is reached after a few minutes. The influence of the sludge characteristics, notably the floc size and the chemical oxygen demand partition between solid and colloidal fraction, on sorption efficiency is demonstrated. A Langmuir modelling allows giving the maximum sorption capacity, as well as the binding energy for the three studied sludges, according to their physicochemical characteristics.

Depletion of Normal and Malignant B cells with a CD37-specific SMIP molecule

3063

Background: CD37 is a member of the tetraspanin family expressed at high levels by normal mature B cells and by most B cell malignancies. Previously, an antibody to CD37 has been labeled with 131I and tested in clinical trials for therapy of NHL. Treatment with 131I-MB-1, resulted in durable tumor remissions in patients lasting from 4 to 11 months (Press OW, Eary JF, Badger CC, et al. Treatment of refractory non-Hodgkin’s lymphoma with radiolabeled MB-1 (anti-CD37) antibody. J Clin Oncol. 1989;7:1027–1038). Here we assess the functional properties and therapeutic potential of a small modular immunopharmaceutical (SMIP) targeting CD37. Methods: Growth arrest and apoptosis of B lymphoma cell lines was assessed. ADCC activity was evaluated using BJAB targets and human peripheral blood mononuclear cells (PBMC) effectors. Drug-drug interactions were assessed by the Combination Index method. In vivo studies were performed utilizing established human B cell tumor xenografts in nude mice. Results: A CD37-directed SMIP drug candidate mediated growth arrest, apoptosis and ADCC, but not CDC, towards B lymphoma cell lines. The protein showed significant anti-tumor activity in a mouse xenograft model, and selectively depleted normal human B cells in short term cultures of PBMC. When combined with rituximab, the molecule increased apoptosis, C1q binding, and C’ dependent target cell death in vitro, and increased anti-tumor activity in vivo in a xenograft model. Conclusions: In vitro and in vivo characterization of the CD37-targeted SMIP drug suggest a potent capacity to eliminate target cells through combined effects of direct target cell signaling and effector cell recruitment. CD37-mediated growth was synergistic with standard chemotherapies in vitro and showed additive in vivo activity with CD20-targeted therapy. On the basis of these data CD37-directed SMIP therapy is being developed for clinical evaluation against B cell malignancies.

No significant financial relationships to disclose.

Alkanediyl-α,ω-Bis(dimethylalkylammonium Bromide) Surfactants

The enthalpies of dilution of micellar solutions of several 12-s-12 dimeric surfactants of the alkanediyl-alpha,omega-bis(dodecyldi-methylammonium bromide) type, differing by the carbon number s of the alkanediyl spacer, and of dodecyltrimethylammonium bromide (DTAB) have been measured calorimetrically, in a range of concentrations extending from well below to well above the critical micelle concentration (cmc). The results permitted the determination of the enthalpy of micellization, DeltaH degrees (M), of the investigated surfactants at 25 and 35 degrees C. The values of DeltaH degrees (M) were always negative and became more negative as the temperature was increased. The plot of -DeltaH degrees (M) against s showed a shallow minimum at about s=5 and a large decrease of -DeltaH degrees (M) going from 12-2-12 to 12- 4-12. This effect has been attributed to the contribution to DeltaH degrees (M) of the hindered rotation of the dodecyl chains around the spacer C-C bond for 12-2-12. This hindrance is shown to rapidly disappear when s is increased from 2 to above 4. The specific heats of micellization, the free energies of micellization, and the entropies of micellization (DeltaS degrees (M)) have been calculated using the DeltaH degrees (M) values and the reported cmc and micelle ionization degree data for 12-s-12 surfactants and DTAB. For all surfactants the results show that TDeltaS degrees (M)>-DeltaH degrees (M), indicating an entropy-driven micellization.

Summary of the first round analyses of the Third International Workshop on Swine Leukocyte Differentiation Antigens

The reactivity of 155 monoclonal antibodies submitted to the Third International Workshop on Swine Leukocyte Differentiation Antigens, together with 41 internal standards, was analysed by flow cytometry on 29 different pig cell targets as well as two human cell targets as a means of establishing suitable panels of monoclonal antibodies for more detailed clustering analyses by the various subsections of the workshop. Results were collected either without further gating, with gating based on FS/SS characteristics or with gating based on the co-expression of a reference antibody in two-colour flow cytometry. The CD or SWC reactivity of the internal standards had been established in previous workshops. Data sets were subsequently analysed by statistical clustering using the Leucocyte Typing Database IV software. The resulting 18 cluster groups were allocated to the appropriate second round sections of the workshop, after reviewing the overall cellular reactivity of each cluster as well as the specificity of known standards which clustered in a group.

Lineage-specific induction of B cell apoptosis and altered signal transduction by the phosphotyrosine phosphatase inhibitor bis(maltolato)oxovanadium(IV)

Protein tyrosine phosphorylation is known to play key roles in lymphocyte signal transduction, and phosphotyrosine phosphatases (PTP) can act as both positive and negative regulators of these lymphocyte signals. We sought to examine the role of PTP further in these processes by characterizing the effects of bis(maltolato)-oxovanadium(IV) (BMLOV), previously known to be a nontoxic insulin mimetic agent in vivo. BMLOV was found to be a potent phosphotyrosine phosphatase inhibitor. BMLOV induced cellular tyrosine phosphorylation in B cells in a pattern similar to that observed following antigen receptor stimulation, whereas little tyrosine phosphorylation was induced in T cells. In B cells, BMLOV treatment resulted in tyrosine phosphorylation of Syk and phospholipase C gamma 2, while sIgM-induced signals were inhibited. By contrast, T cell receptor signals were moderately increased by BMLOV, and the cells displayed greater induction of IL-2 receptor without toxicity. The compound selectively induced apoptosis in B cell lymphoma and myeloid leukemia cell lines, but not in T cell leukemia or colon carcinoma cells. Interleukin-4 plus anti-CD40 antibody treatment of normal human peripheral B cells rescued the cells from BMLOV-induced death. These results suggest that phosphotyrosine phosphatase inhibitors can activate B cell signal pathways in a lineage-specific manner, resulting in desensitization of receptor-mediated signaling and induction of apoptosis.

CD28 engagement by B7/BB-1 induces transient down-regulation of CD28 synthesis and prolonged unresponsiveness to CD28 signaling

Costimulatory molecules on the APC regulate T cell growth by providing signals that regulate responses to TCR occupancy. One such molecule is B7/BB-1, which triggers a T cell activation pathway by binding the CD28 and/or CTLA-4 cell-surface molecules. Expression and signaling activity of CD28 have been shown to increase after T cell activation by various polyclonal activators. Here we show that CD28 expression and signaling activity in activated T cells decrease after ligand binding to CD28. Stimulation of CD28 on PHA- or PMA-activated T cells by cross-linked mAb 9.3 or by co-culture with B7+ Chinese hamster ovary (CHO) cells caused a marked reduction of CD28 mRNA levels within 4 h. The decrease in CD28 mRNA was transient, and by 24 h of CD28 stimulation, CD28 mRNA was found at approximately initial levels. In contrast, CTLA-4 mRNA levels were usually up-regulated by CD28 triggering. Cell-surface expression of CD28, but not CD2 or CD3, decreased by 12 to 24 h after addition of B7+ CHO cells, but returned to initial levels or higher by 48 h. The ability of CD28 cross-linking on PMA-activated CD4+ cells to trigger calcium mobilization was also reduced by treatment with B7+ CHO cells, and remained reduced even after cell-surface expression of CD28 returned to normal levels. Thus, engagement of the CD28 receptor by its natural ligand B7/BB-1 leads to a transient down-regulation of CD28 synthesis and a prolonged unresponsiveness to CD28 signaling. This represents a novel mechanism for regulation of costimulatory signals delivered by interactions of CD28 with the B7/BB-1 counter receptor.

CD28 engagement by B7/BB-1 induces transient down-regulation of CD28 synthesis and prolonged unresponsiveness to CD28 signaling

Costimulatory molecules on the APC regulate T cell growth by providing signals that regulate responses to TCR occupancy. One such molecule is B7/BB-1, which triggers a T cell activation pathway by binding the CD28 and/or CTLA-4 cell-surface molecules. Expression and signaling activity of CD28 have been shown to increase after T cell activation by various polyclonal activators. Here we show that CD28 expression and signaling activity in activated T cells decrease after ligand binding to CD28. Stimulation of CD28 on PHA- or PMA-activated T cells by cross-linked mAb 9.3 or by co-culture with B7+ Chinese hamster ovary (CHO) cells caused a marked reduction of CD28 mRNA levels within 4 h. The decrease in CD28 mRNA was transient, and by 24 h of CD28 stimulation, CD28 mRNA was found at approximately initial levels. In contrast, CTLA-4 mRNA levels were usually up-regulated by CD28 triggering. Cell-surface expression of CD28, but not CD2 or CD3, decreased by 12 to 24 h after addition of B7+ CHO cells, but returned to initial levels or higher by 48 h. The ability of CD28 cross-linking on PMA-activated CD4+ cells to trigger calcium mobilization was also reduced by treatment with B7+ CHO cells, and remained reduced even after cell-surface expression of CD28 returned to normal levels. Thus, engagement of the CD28 receptor by its natural ligand B7/BB-1 leads to a transient down-regulation of CD28 synthesis and a prolonged unresponsiveness to CD28 signaling. This represents a novel mechanism for regulation of costimulatory signals delivered by interactions of CD28 with the B7/BB-1 counter receptor.

Superantigen and HLA-DR ligation induce phospholipase-C gamma 1 activation in class II+ T cells

Bacterial enterotoxin superantigens bind directly to HLA class II molecules (HLA-DR) expressed on both APC and activated human T cells, and simultaneously bind to certain V beta chains of the TCR. In this report, we compared early T cell signaling events in human alloantigen-stimulated T cells when activated by HLA-DR ligation through antibody cross-linking or by direct enterotoxin superantigen binding. Both types of stimuli induced tyrosine phosphorylation of phosphatidylinositol-specific phospholipase C gamma 1 (PLC gamma 1) and an increase in intracellular calcium concentration; however, superantigen-induced signaling was stronger than class II ligation alone. Antibody-mediated ligation of HLA-DR with CD3 resulted in augmented PLC gamma 1 activation and increased calcium mobilization, consistent with a mechanism of superantigen activity through a combination of class II and CD3/Ti signals. In addition, down-modulation of CD3 receptors with antibody demonstrated that superantigen-induced signaling events were CD3-dependent. Superantigen signaling was also class II-dependent, in that resting T cells were not responsive to direct enterotoxin stimulation. To address how early signal transducing activity correlated with T cell responsiveness, alloantigen-primed T cells were activated with immobilized class II-specific mAb or soluble superantigen. Both HLA-DR mAb-stimulated T cells and enterotoxin-treated T cells proliferated strongly in response to co-stimulation by a combination of CD28 receptor engagement and PMA addition. In addition, superantigen-induced growth was induced by CD28 receptor ligation with antibody or the B7 counter-receptor expressed on Chinese hamster ovary cells. Taken together, these results indicate that class II molecules expressed on activated T cells are directly coupled to the PLC gamma 1 signal transduction pathway, and that coligation of HLA-DR with CD3 augments T cell signaling comparable to that induced by enterotoxin superantigen. Thus, we suggest that superantigen-induced early signaling responses in activated T cells may be due in part to class II transmembrane signals induced when HLA-DR and V beta are ligated in cis.

Superantigen and HLA-DR ligation induce phospholipase-C gamma 1 activation in class II+ T cells

Bacterial enterotoxin superantigens bind directly to HLA class II molecules (HLA-DR) expressed on both APC and activated human T cells, and simultaneously bind to certain V beta chains of the TCR. In this report, we compared early T cell signaling events in human alloantigen-stimulated T cells when activated by HLA-DR ligation through antibody cross-linking or by direct enterotoxin superantigen binding. Both types of stimuli induced tyrosine phosphorylation of phosphatidylinositol-specific phospholipase C gamma 1 (PLC gamma 1) and an increase in intracellular calcium concentration; however, superantigen-induced signaling was stronger than class II ligation alone. Antibody-mediated ligation of HLA-DR with CD3 resulted in augmented PLC gamma 1 activation and increased calcium mobilization, consistent with a mechanism of superantigen activity through a combination of class II and CD3/Ti signals. In addition, down-modulation of CD3 receptors with antibody demonstrated that superantigen-induced signaling events were CD3-dependent. Superantigen signaling was also class II-dependent, in that resting T cells were not responsive to direct enterotoxin stimulation. To address how early signal transducing activity correlated with T cell responsiveness, alloantigen-primed T cells were activated with immobilized class II-specific mAb or soluble superantigen. Both HLA-DR mAb-stimulated T cells and enterotoxin-treated T cells proliferated strongly in response to co-stimulation by a combination of CD28 receptor engagement and PMA addition. In addition, superantigen-induced growth was induced by CD28 receptor ligation with antibody or the B7 counter-receptor expressed on Chinese hamster ovary cells. Taken together, these results indicate that class II molecules expressed on activated T cells are directly coupled to the PLC gamma 1 signal transduction pathway, and that coligation of HLA-DR with CD3 augments T cell signaling comparable to that induced by enterotoxin superantigen. Thus, we suggest that superantigen-induced early signaling responses in activated T cells may be due in part to class II transmembrane signals induced when HLA-DR and V beta are ligated in cis.

Genetic construction and characterization of a fusion protein consisting of a chimeric F(ab') with specificity for carcinomas and human IL-2

A genetic construct was created incorporating gene fragments encoding the H chain V region of the human carcinoma specific antibody L6, the CH1 domain of human IgG1, a linker region, and human IL-2. This construct was cotransfected with a chimeric L6 L chain construct into the murine myeloma cell line Ag8.653 for expression. First round clones produced the fusion protein at an estimated 5 to 10 micrograms/ml based on idiotypic reactivity. Dual binding activity was demonstrated through specific interaction with the L6 Ag on human tumor cells and the IL-2R on activated human T cells. The IL-2 portion of the molecule was shown to support the growth of the IL-2-dependent T cell line CTLL2, and the qualitative nature of the IL-2 signal was found to be the same as rIL-2 with respect to induction of tyrosine-phosphorylation of intracellular protein substrates. Tumor cells coated with the fusion protein were shown to cause T cell proliferation and the presence of the fusion protein was found to enhance cell-mediated destruction of human tumor cells.

Genetic construction and characterization of a fusion protein consisting of a chimeric F(ab') with specificity for carcinomas and human IL-2

A genetic construct was created incorporating gene fragments encoding the H chain V region of the human carcinoma specific antibody L6, the CH1 domain of human IgG1, a linker region, and human IL-2. This construct was cotransfected with a chimeric L6 L chain construct into the murine myeloma cell line Ag8.653 for expression. First round clones produced the fusion protein at an estimated 5 to 10 micrograms/ml based on idiotypic reactivity. Dual binding activity was demonstrated through specific interaction with the L6 Ag on human tumor cells and the IL-2R on activated human T cells. The IL-2 portion of the molecule was shown to support the growth of the IL-2-dependent T cell line CTLL2, and the qualitative nature of the IL-2 signal was found to be the same as rIL-2 with respect to induction of tyrosine-phosphorylation of intracellular protein substrates. Tumor cells coated with the fusion protein were shown to cause T cell proliferation and the presence of the fusion protein was found to enhance cell-mediated destruction of human tumor cells.

Binding of the B cell activation antigen B7 to CD28 costimulates T cell proliferation and interleukin 2 mRNA accumulation

A successful immune response requires intercellular contact between T and B lymphocytes. We recently showed that CD28, a T cell surface protein that regulates an activation pathway, could mediate intercellular adhesion with activated B cells by interaction with the B7 antigen. Here we show that CD28 is the primary receptor for B7 on activated peripheral blood T cells, that CD28 binds to B7 in the absence of other accessory molecules, and that interaction between CD28 and B7 is costimulatory for T cell activation. To characterize the binding of CD28 to B7, we have produced genetic fusions of the extracellular portions of B7 and CD28, and immunoglobulin (Ig) C gamma 1 chains. 125I-labeled B7 Ig bound to CD28-transfected Chinese hamster ovary (CHO) cells, and to immobilized CD28 Ig with a Kd approximately 200 nM. B7 Ig also inhibited CD28-mediated cellular adhesion. The function of CD28-B7 interactions during T cell activation was investigated with soluble fusion proteins and with B7-transfected CHO cells. Immobilized B7 Ig and B7+ CHO cells costimulated T cell proliferation. Stimulation of T cells with B7+ CHO cells also specifically increased levels of interleukin 2 transcripts. These results demonstrate that the CD28 signaling pathway could be activated by B7, resulting in increased T cell cytokine production and T cell proliferation. Cellular interactions mediated by B7 and CD28 may represent an important component of the functional interactions between T and B lymphoid cells.