Regulatory T cell responses in areas where Plasmodium falciparum and Schistosoma haematobium infections coexist: disentangling co-infection

• Applicant: Professor Dr. Peter Gottfried Kremsner
• Co-Applicant: Professor Ayola Akim Adegnika, Ph.D.
• Subject Area: Parasitology and Biology of Tropical Infectious Disease Pathogens
• Term: from 2009 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 83350897

There is no need to emphasize the importance of malarial infections in the tropics and its devastating effect globally resulting in over two million deaths per year. P. falciparum is highly endemic in Gabon and figures from the health surveys in the study area of Lambarene have shown that P. falciparum and helminth infections frequently co-exist (Adegnika et al. 2007). It is known that helminth infections have strong immune modulatory effects, which may affect responses to unrelated antigens (Maizels & Yazdanbakhsh, 2003; Su et al. 2006) interestingly, early studies in 1970's had indicated that malaria is associated with immune suppression whereby responses to unrelated antigens were affected (Greenwood et al. 1972). In recent years, evidence is accumulating for the ability of P. falciparum parasites to induce regulatory responses not only during malarial episode but also when asymptomatic (Bejon et al. 2007; Walther et al. 2005).Regulatory T cells have received much attention, and seem to be central to the maintenance of a well balanced immune system (Sakaguchi et al. 2008). Their dysfunction is associated with overt inflammatory reactions, whereas their overt expression can compromise effective immune responses to vaccines or to incoming pathogens (Couper et al. 2008). In fact some successful parasites appear to have the ability to induce regulatory T cells in order to enhance their survival within their host (Walther et al. 2005).There is little information on the nature of regulatory T cells that might be involved in the immune suppression that is often seen during helminth infections, nor is there much known of their function during P. falciparum infections. More importantly, there is nothing known about the activity of Treg cells during coinfection.In Lambarene, Gabon, we have been conducting studies for more than a decade and have accurate information on the epidemiology of P. falciparum and helminth infections which include Schistosoma haematobium. The current proposal will study regulatory T cells during P. falciparum and S. haematobium coinfections. It will utilize techniques already established in Gabon to assess the phenotype and function of regulatory T cells.Such data could have important implications for understanding the significance of coinfections clinically and for paving the way for testing new candidate vaccines, including those for malaria, in areas where helminths are often coendemic.

• DFG Programme: Research Grants
• International Connection: Gabon
• Major Instrumentation: Multiplex cytokines measurement system
• Participating Person: Professor Dr. Benjamin G. Mordmüller