Tracking the Feeding Patterns of Tsetse Flies (Glossina Genus) by Analysis of Bloodmeals Using Mitochondrial Cytochromes Genes

Tsetse flies are notoriously difficult to observe in nature, particularly when populations densities are low. It is therefore difficult to observe them on their hosts in nature; hence their vertebrate species can very often only be determined indirectly by analysis of their gut contents. This knowledge is a critical component of the information on which control tactics can be developed. The objective of this study was to determine the sources of tsetse bloodmeals, hence investigate their feeding preferences. We used mitochondrial cytochrome c oxidase 1 (COI) and cytochrome b (cytb) gene sequences for identification of tsetse fly blood meals, in order to provide a foundation for rational decisions to guide control of trypanosomiasis, and their vectors. Glossina swynnertoni were sampled from Serengeti (Tanzania) and G. pallidipes from Kenya (Nguruman and Busia), and Uganda. Sequences were used to query public databases, and the percentage identities obtained used to identify hosts. An initial assay showed that the feeds were from single sources. Hosts identified from blood fed flies collected in Serengeti ecosystem, included buffaloes (25/40), giraffes (8/40), warthogs (3/40), elephants (3/40) and one spotted hyena. In Nguruman, where G. pallidipes flies were analyzed, the feeds were from elephants (6/13) and warthogs (5/13), while buffaloes and baboons accounted for one bloodmeal each. Only cattle blood was detected in flies caught in Busia and Uganda. Out of four flies tested in Mbita Point, Suba District in western Kenya, one had fed on cattle, the other three on the Nile monitor lizard. These results demonstrate that cattle will form an integral part of a control strategy for trypanosomiasis in Busia and Uganda, while different approaches are required for Serengeti and Nguruman ecosystems, where wildlife abound and are the major component of the tsetse fly food source

Phylogeography and Population Structure of Glossina fuscipes fuscipes in Uganda: Implications for Control of Tsetse

Glossina fuscipes fuscipes is the most common species of tsetse in Uganda, where it transmits human sleeping sickness and nagana, a related disease of cattle. A consortium of African countries dedicated to controlling these diseases is poised to begin area wide control of tsetse, but a critical question remains: What is the most appropriate geographical scale for these activities? To address this question, we used population genetics to determine the extent of linkage between populations of tsetse confined to discrete patches of riverine habitat. Our results suggest that Uganda was colonized by two distinct lineages of G. f. fuscipes, which now co-occur only in a narrow band across central Uganda. Evidence for interbreeding at the zone of contact and movement of genes from the south to the north suggest that this historical genetic structure may dissolve in the future. At smaller scales, we have demonstrated that exchange of genes among neighboring populations via dispersal is at equilibrium with the differentiating force of genetic drift. Our results highlight the need for investment in vector control programs that account for the linkage observed among tsetse populations. Given its genetic isolation and its location at the far edge of G. fuscipes' range, the Lake Victoria region appears to be an appropriate target for area wide control

Angiogenesis in Differentiated Placental Multipotent Mesenchymal Stromal Cells Is Dependent on Integrin α5β1

Human placental multipotent mesenchymal stromal cells (hPMSCs) can be isolated from term placenta, but their angiogenic ability and the regulatory pathways involved are not known. hPMSCs were shown to express integrins αv, α4, α5, β1, β3, and β5 and could be induced to differentiate into cells expressing endothelial markers. Increases in cell surface integrins α5 and β1, but not α4, αvβ3, or αvβ5, accompanied endothelial differentiation. Vascular endothelial growth factor-A augmented the effect of fibronectin in enhancing adhesion and migration of differentiated hPMSC through integrin α5β1, but not αvβ3 or αvβ5. Formation of capillary-like structures in vitro from differentiated cells was inhibited by pre-treatment with function-blocking antibodies to integrins α5 and β1. When hPMSCs were seeded onto chick chorioallantoic membranes (CAM), human von Willebrand factor-positive cells were observed to engraft in the chick endothelium. CAMs transplanted with differentiated hPMSCs had a greater number of vessels containing human cells and more incorporated cells per vessel compared to CAMs transplanted with undifferentiated hPMSCs, and overall angiogenesis was enhanced more by the differentiated cells. Function-blocking antibodies to integrins α5 and β1 inhibited angiogenesis in the CAM assay. These results suggest that differentiated hPMSCs may contribute to blood vessel formation, and this activity depends on integrin α5β1

Adenosine and cAMP signalling skew human dendritic cell differentiation towards a tolerogenic phenotype with defective CD8+ T-cell priming capacity

Multiple endogenous mechanisms that regulate immune and inflammatory processes contribute to the maintenance of peripheral tolerance and prevent chronic inflammation in mammals. Yet pathogens and tumours are able to exploit these homeostatic pathways to foster immunosuppressive microenvironments and evade immune surveillance. The release of adenosine in the extracellular space contributes to these phenomena by exerting a broad range of immunomodulatory effects. Here we document the influence of adenosine receptor triggering on human dendritic cell differentiation and functions. We show that the expression of several immunomodulatory proteins and myeloid/monocytic lineage markers was affected by adenosine receptors and the cAMP pathway. These changes were reminiscent of the phenotype associated with tolerogenic dendritic cells and, functionally, translated into a defective capacity to prime CD8+ T-cells with a common tumour antigen in vitro. These results establish a novel mechanism by which adenosine hampers CD8+ T-cell immunity via dendritic cells that may contribute to peripheral tolerance as well as to the establishment of immunosuppressive microenvironments relevant to tumour biology

Environmental and stock effects on recruitment variability in the English Channel squid

Recruitment variability is commonly attributed to variation in spawning stock size and environmental variability. Here, the abundance of Loligo forbesi in the English Channel was estimated using cohort analysis. Environmental and adult biomass effects on recruitment variation were then tested. A stochastic length-age key was included in the cohort analysis, considering inter-individual variability in age at length. The number of recruits and parental stock biomass per monthly age-class were computed for a series of 13 fishing seasons (1989-2002). Recruitment was examined in relation to adult biomass and environmental parameters (sea surface temperature, SST, and the North Atlantic Oscillation, NAO) at the time of hatching. Recruits were approximately 7 months old and recruitment for each annual cohort occurred between April and August. Squid bigger than the length at maturity were assumed to be spawners. In the spawning season (September December), spawners were 11–13 months old. Parametric stock-recruitment curves (Ricker, Beverton and Holt, Shepherd, etc.) fitted poorly, while SST was negatively correlated with recruitment in a simple linear model. Recruitment was unrelated to NAO. A model combining SST and adult biomass showed that recruitment is probably density-dependent when stock size is high, and negatively correlated with temperature. The study did not indicate obvious recruitment overfishing in the English Channel L. forbesi population

Tumor-targeted 4-1BB agonists for combination with T cell bispecific antibodies as off-the-shelf therapy

Endogenous costimulatory molecules on T cells such as 4-1BB (CD137) can be leveraged for cancer immunotherapy. Systemic administration of agonistic anti-4-1BB antibodies, although effective preclinically, has not advanced to phase 3 trials because they have been hampered by both dependency on Fc gamma receptor-mediated hyperclustering and hepatotoxicity. To overcome these issues, we engineered proteins simultaneously targeting 4-1BB and a tumor stroma or tumor antigen: FAP-4-1BBL (RG7826) and CD19-4-1BBL. In the presence of a T cell receptor signal, they provide potent T cell costimulation strictly dependent on tumor antigen-mediated hyperclustering without systemic activation by Fc gamma R binding. We could show targeting of FAP-4-1BBL to FAP-expressing tumor stroma and lymph nodes in a colorectal cancer-bearing rhesus monkey. Combination of FAP-4-1BBL with tumor antigen-targeted T cell bispecific (TCB) molecules in human tumor samples led to increased IFN-gamma and granzyme B secretion. Further, combination of FAP- or CD19-4-1BBL with CEA-TCB (RG7802) or CD20-TCB (RG6026), respectively, resulted in tumor remission in mouse models, accompanied by intratumoral accumulation of activated effector CD8(+) T cells. FAP- and CD19-4-1BBL thus represent an off-the-shelf combination immunotherapy without requiring genetic modification of effector cells for the treatment of solid and hematological malignancies