3.1.     Co-infection of nematodes with the bacterial pathogen Salmonella

Intestinal nematode infections affect approximately 24% of the world's population. In areas with helminth infections such as soil-transmitted helminths, co-infections with protozoa such as plasmodia or giardia (Fig. 1) are common (Schlosser Brandenburg et al., 2023).

An experimental co-infection of pigs with the roundworm A. suum and the bacterial pathogen Salmonella Typhimurium showed that the roundworm infection modulated the immune response in pigs leading to a poorer control of salmonellosis in pigs.

3.2.     Toxoplasma-nematode coinfection: redirection of the immune response

Since the seroprevalence of Toxoplasma is particularly high in tropical areas (up to 70%) and Toxoplasma gondii elicits an opposite immune response compared to nematodes, we experimentally analyzed this coinfection. A preceding T. gondii infection leads to increased worm fecundity, which is accompanied by a massive suppression of the H. polygyrus-specific Th2 response. The numbers of IL-4, IL-5 and IL-13 producing GATA-3⁺ Th2 cells and eosinophils as well as the expression of the effector molecule RELM-b in the intestinal tissue of co-infected mice were massively reduced in a preceding T. gondii infection (Ahmed et al, 2017, Ahmed et al. 2019).

Selected Publications

• Schlosser-Brandenburg, J.; Midha, A.; Mugo, R. M.; Ndombi, E. M.; Gachara, G.; Njomo, D.; Rausch, S.; Hartmann, S. (2023): Infection with soil-transmitted helminths and their impact on coinfections. Front Para; 2, S. Artikel 1197956
• Ahmed, N.; Heitlinger, E.; Affinass, N.; Kühl, A. A.; Xenophontos, N.; Jarquin, V. H.; Jost, J.; Steinfelder, S.; Hartmann, S. (2019): A Novel Non-invasive Method to Detect RELM Beta Transcript in Gut Barrier Related Changes During a Gastrointestinal Nematode Infection. Front Immunol; 10, S. 445
• Ahmed, N., T. French, S. Rausch, A. A. Kühl, K. Hemminger, I. R. Dunay, S. Steinfelder, S. Hartmann (2017): Toxoplasma co-infection prevents Th2 differentiation and leads to a helminth-specific Th1 response. Frontiers in Cellular and Infection Microbiology, doi:10.3389/fcimb.2017.00341.
• Maaz, D., S. Rausch, D. Richter, J. Krücken, A.A. Kühl, J. Demeler, J. Blümke, F.R. Matuschka, G. von Samson-Himmelstjerna, S. Hartmann (2016): Susceptibility to ticks and lyme disease spirochetes is not affected in mice coinfected with nematodes. Infection and Immunity, 84: 1274-1286.

Third-party funding: DFG GRK 2046: S. Hartmann Project B4 und DFG Individual Research Grant: S. Hartmann