Intestinal nematodes live in close contact with the intestinal microbiota of their hosts and some species such as roundworms also migrate from the intestine into other tissues. Nevertheless, there are hardly any systemic inflammatory immune reactions of the host. Little is known about the reciprocal interaction of the worms with the surrounding microbiota and the underlying mechanisms of mutual interaction (Fig. 1).

We were able to show that infections with intestinal nematodes cause shifts in the microbiota composition and diversity (Rausch et al., 2013, Midha et al., 2023). The porcine roundworm A. suum influences the surrounding microbiota of the host and the nematodes benefit from the altered microbiota (Midha et al., 2021). We showed nematodes to release products with antimicrobial activity. These nematode antimicrobials interfere with bacterial growth, counteract bacterial biofilm formation and lead to the neutralization of bacteria through agglutination (Midha et al., 2017, Midha et al., 2018). The microbiome of the nematodes (a gut within a gut) is determined by the host microbiome (Midha et al., 2023).

Selected publications:

• Midha, A.; Jarquín-Díaz, V. H.; Ebner, F.; Löber, U.; Hayani, R.; Kundik, A.; Cardilli, A.; Heitlinger, E.; Forslund, S. K.; Hartmann, S. (2022): Guts within guts: the microbiome of the intestinal helminth parasite Ascaris suum is derived but distinct from its host. Microbiome; 10(1), S. Article number: 229
• Elizalde‐Velázquez, L. E.; Yordanova, I. A.; Liublin, W.; Adjah, J.; Leben, R.; Rausch, S.; Niesner, R.; Hartmann, S. (2023):Th2 and metabolic responses to nematodes are independent of prolonged host microbiota abrogation. Para Immunol; 45(4 : Special Issue: Parasites and the Microbiota), S. Article e12957
• Midha, A.; Goyette-Desjardins, G.; Gordeler, F.; Mocovitz, O.; Seeberger, P. H.; Tedin, K.; Bertzbach, L. D.; Lepenies, B.; Hartmann, S. (2021):Lectin-mediated bacterial modulation by the intestinal nematode Ascaris suum.Int J Mol Sci; 22(16), S. Artikel 8739
• Midha, A.; Ebner, F.; Schlosser-Brandenburg, J.; Rausch, S.; Hartmann, S. (2021): Trilateral relationship: ascaris, microbiota, and host cells.Trends Parasitology; 37(3), S. 251–262
• Midha, A.; Janek, K.; Niewienda, A.; Henklein, P.; Günther, S.; Serra, D. O.; Schlosser, J.; Hengge, R.; Hartmann, S. (2018):The Intestinal Roundworm Ascaris suum Releases Antimicrobial Factors Which Interfere With Bacterial Growth and Biofilm Formation. Frontiers in Cellular and Infection Microbiology; 8, S. Artikelnr. 271
• Midha, A., J. Schlosser, S. Hartmann (2017): Reciprocal Interactions between Nematodes and Their Microbial Environments. Frontiers in Cellular and Infection Microbiology, doi: 10.3389/fcimb.2017.00144
• Rausch, S., J. Held, A. Fischer, M. M. Heimesaat, A. A. Kühl, S. Bereswill, and S. Hartmann (2013): Small intestinal nematode infection of mice is associated with increased enterobacterial loads alongside the intestinal tract. PLoS ONE, 8: e74026.

Third party funding: DFG GRK 2046: S. Hartmann Projekt B4 and B4 associated.