Trypanosoma cruzi: lack of T cell abnormalities in mice vaccinated with live trypomastigotes

We have previously shown that inoculation of Trypanosoma cruzi clone-CL-14 generates efficient protective immunity against virulent T. cruzi and no infection or histopathology per se, indicating that it induces an immune state different from that exhibited by infected animals. To understand the basis of this difference, we screened CL-14-vaccinated mice for T cell abnormalities thought to be involved in the genesis of pathology. Lymphocytes from vaccinated mice present normal proliferative responses to concanavalin A; enhanced responses to T. cruzi antigens; do not show evidence of polyclonal activation (increased blast transformation and lymphocyte numbers) or changes in the density of CD4, CD8 and TCR-β expression. Also, vaccinated mice display transient expansion of CD8⁺ lymphocytes expressing activated phenotypes (CD11a^hi CD45RB^lo CD62L^lo). In view of the absence of pathology in vaccinated animals, the absence of immunosuppression and the restoration of a resting immune state reinforce the benign nature of this immunization. Received: 30 March 1999 / Accepted: 15 June 1999     

Immunogenicity of synthetic peptide constructs based on PvMSP9E795-A808, a linear B-cell epitope of the P. vivax Merozoite Surface Protein-9

Plasmodium vivax Merozoite Surface Protein-9 (PvMSP-9) is a malaria vaccine candidate naturally immunogenic in humans and able to induce high antibody titers in animals when delivered as a recombinant protein. Recently, we identified the sequence EAAPENAEPVHENA (PvMSP9_E795-A808) as the main linear B-cell epitope in naturally exposed individuals. However, the potential of PvMSP9_E795-A808 as an immunogen in experimental animal models remained unexplored. Here we assess the immunogenicity of PvMSP9_E795-A808 using synthetic peptides. The peptides tested in BALB/c mice include two repeats of the sequence EAAPENAEPVHENA tested alone (peptide RII), or linked to an autologous (PvMSP9 peptide pL; pLRII) or heterologous (p2 tetanus toxin universal T cell epitope; TTRII) T cell epitope. Immune responses were evaluated by ELISA, FLUOROSPOT, and indirect immunofluorescence. We show that all of the peptide constructs tested were immunogenic eliciting specific IgG antibodies at different levels, with a prevalence of IgG1 and IgG2. Animals immunized with synthetic peptides containing T cell epitopes (pLRII or TTRII) had more efficient antibody responses that resulted in higher antibody titers able to recognize the native protein by immunofluorescence. Relevantly, the frequency of IFN-γ secreting SFC elicited by immunization with TTRII synthetic peptide was comparable to that reported to the PvMSP9-Nt recombinant protein. Taken together, our study indicates that PvMSP9_E795-A808 is highly immunogenic in mice and further studies to evaluate its value as promising vaccine target are warranted. Moreover, our study supports the critical role of CD4 T cell epitopes to enhance humoral responses induced by subunit based vaccines.     

Extracellular matrix components of the mouse thymic microenvironment. III. Thymic epithelial cells express the VLA6 complex that is involved in laminin-mediated interactions with thymocytes

We describe herein the expression of the VLA6 complex by murinethymic epithelial cells (TEC). The immunohistochemical distributionrevealed that VLA6 is found in both thymic medullary and subcapsullaryareas. Moreover, studies by immunoelectron microscopy revealeda membrane labeling of the VLA6 molecule, including at desmosomalsites. By means of immunoblottlng, immunoprecipitation, andaffinity chromatography of extracts from a mouse TEC line, wefurther demonstrated that VLA6 is a laminin (LN) receptor inthese cells. In keeping with this finding, we showed that TECadhesion, spreading, and proliferation were enhanced in vitroby LN. The fact that VLA6 is also expressed by the large majorityof thymocytes raised the hypothesis that it might be involvedin LN-mediated TEC—thymocyte interactions. Interestingly,in vitro experiments showed that there is an increase in theTEC—thymocyte adhesion upon glucocorticold hormone treatment,a situation in which the expression of VLA6 as well as LN isenhanced. Most importantly, this adhesion can be reversed bypre-treating TEC with an anti-6 integrin mAb. Additionally,spontaneous in vitro thymocyte release by thymic nurse cellcomplexes was enhanced by LN and partially blocked by anti-6or anti-ß1 antibodies. Our results suggest that VLA6is involved in LN-mediated TEC—thymocyte interactionsthat can be relevant for thymic microenvironmental cell physiologyand intrathymic T cell differentiation events.     

Differential expression of fibroblast growth factor-2 and receptor by glial cells in experimental autoimmune encephalomyelitis (EAE)

To assess the expression pattern of basic fibroblast growth factor (FGF-2) and one of its receptors (FGFR-1/flg) during autoimmune inflammation of the CNS, FGF-2, and FGFR1/flg peptide and mRNA levels were examined by immunocytochemistry, by in situ hybridisation and by Northern blot analysis in T cell-mediated EAE of the Lewis rat. In naive control animals as well as in animals injected with nonencephalitogenic, PPD-reactive T lymphocytes, FGF-2 immunoreactivity was low and confined to blood vessels and to a few spinal cord neurons. In rats injected with encephalitogenic, MBP-reactive T lymphocytes, however, FGF-2-immunoreactive cells were detected from day 4 after T cell transfer onward, i.e., from the onset of clinical symptoms. The number of FGF-2 immunoreactive cells was highest between days 6 and 10 after T cell transfer. Increased FGF-2 peptide expression was paralleled by increased FGF-2 mRNA expression on macrophages/microglia in the spinal cord. By 21 days after T cell transfer, i.e. after complete recovery, FGF-2 peptide and mRNA expression had fully subsided. Based on morphological criteria and on double labeling with the macrophage/microglia-binding lectin GSI-B₄ two cell types expressed FGF-2: 1) round macrophages within the core, and 2) activated microglia at the edges of white and grey matter perivascular lesions. Paralleling the temporal and spatial expression pattern of FGF-2, FGFR-1/flg immunoreactivity was induced on activated macrophages/microglia but also on reactive astrocytes bordering perivascular inflammatory lesions. In situ hybridisation analysis furthermore showed that macrophages/microglia expressed the FGFR-1/flg mRNA, and that receptor mRNA expression paralleled ligand mRNA expression. Macrophage/microglia-derived FGF-2 could serve two main functions in EAE: 1) regulate microglial activation in an autocrine fashion, and 2) help to target astrocyte-derived insulin-like growth factor-I (IGF-I) to potentially injured oligodendrocytes in demyelination. © 1996 Wiley-Liss, Inc.     

A Single Dose of a DNA Vaccine Encoding Apa Coencapsulated with 6,6′-Trehalose Dimycolate in Microspheres Confers Long-Term Protection against Tuberculosis in Mycobacterium bovis BCG-Primed Mice

Mycobacterium bovis BCG prime DNA (Mycobacterium tuberculosis genes)-booster vaccinations have been shown to induce greater protection against tuberculosis (TB) than BCG alone. This heterologous prime-boost strategy is perhaps the most realistic vaccination for the future of TB infection control, especially in countries where TB is endemic. Moreover, a prime-boost regimen using biodegradable microspheres seems to be a promising immunization to stimulate a long-lasting immune response. The alanine proline antigen (Apa) is a highly immunogenic glycoprotein secreted by M. tuberculosis. This study investigated the immune protection of Apa DNA vaccine against intratracheal M. tuberculosis challenge in mice on the basis of a heterologous prime-boost regimen. BALB/c mice were subcutaneously primed with BCG and intramuscularly boosted with a single dose of plasmid carrying apa and 6,6′-trehalose dimycolate (TDM) adjuvant, coencapsulated in microspheres (BCG-APA), and were evaluated 30 and 70 days after challenge. This prime-boost strategy (BCG-APA) resulted in a significant reduction in the bacterial load in the lungs, thus leading to better preservation of the lung parenchyma, 70 days postinfection compared to BCG vaccinated mice. The profound effect of this heterologous prime-boost regimen in the experimental model supports its development as a feasible strategy for prevention of TB.     

High doses of laser phototherapy can increase proliferation in melanoma stromal connective tissue

It is well established that laser phototherapy (LP) is contraindicated directly over cancer cells, due to its bio modulatory effects in cell and blood vessel proliferation. The aim of the present study was to analyze the influence of typical low-level laser therapy (LLLT) and high intensity laser therapy (HILT) and an in-between dose of 9 J on collagen fibers and blood vessels content in melanoma tumors (B16F10) implanted in mice. Melanoma tumor cells were injected in male Balb C mice which were distributed in four groups: control (no irradiated) or irradiated by 3, 9, or 21 J (150; 450, or 1050 J/cm²). LP was performed in daily sessions for 3 days with a InGaAlP—660 nm (mean output: 50 mW, spot size: 2 mm²). Tumor volume was analyzed using (1) picrosirius staining to quantify collagen fibers content and (2) Verhoeff’s method to quantify blood vessels content. Tumor growth outcome measured in the 3-J group was not significantly different from controls. Nine and 21-J groups, presented significant and dose-dependent increases in tumor volume. Quantitative analysis of the intensity of collagen fibers and their organization in stroma and peri-tumoral microenvironment showed significant differences between irradiated and control group. Blood vessels count of 21-J group outnumbered the other groups. High doses (≥ 9 J) of LP showed a dose-dependent tumor growth, different collagen fibers characteristics, and eventually blood vessel growth, while a typical LLLT dose (3 J) appeared harmless on melanoma cell activity.     

HLA class II and antibody responses to circumsporozoite protein repeats of P. vivax (VK210, VK247 and P. vivax-like) in individuals naturally exposed to malaria

We studied the seroreactivity against the circumsporozoite protein (CSP) repeats of Plasmodium vivax variants in individuals living in malaria-endemic area of the Brazilian Amazon region (Candeias do Jamari - RO). The prevalence of IgG antibodies for at least one of the P. vivax CSP repeats was 49%. Among these positive individuals, 34.2% were positive for the standard repeat sequence VK210, 24% for the VK247 and 31.5% for the P. vivax-like sequence. HLA typing showed an association between antibody responses to the CS repeats of VK247 and the presence of HLA-DR16 and between HLA-DR7 and the absence of antibody responses to the CS repeats of VK210. We also investigated the potential relationship between HLA-DQB1 allele profile and antibody response to the CSP repeats of P. vivax but no segregation with responding profile was evidenced. The observed findings indicate that antibody responses to the CSP repeats of P. vivax variants appear to be modulated by HLA class II molecules in malaria naturally exposed individuals.     

The importance of a shared vision in emergency preparedness: engaging partners in a home-rule state

This article discusses the importance of having a strong vision and culture within the context of emergency preparedness in a home-base state. It proposes a broader vision of public health, one that places public health emergency preparedness and response squarely at the center of the public health mission as a core function. It also lays out work currently underway and the future direction for maximizing the value of response-oriented partnerships at the state and local levels in the Evergreen State. The role of health care professionals and dental providers is specified in more detail. Broadening the public health vision requires recognition of the importance of multisectorial partnerships and their response potential, including the potential roles of all health-related professions and the development of systems to use that potential effectively.