Photorhabdus lectins disrupt the activity of insect and human immune system
|Year of publication
|MU Faculty or unit
|Bacteria of the genus Photorhabdus are known as potent entomopathogens that produce a variety of toxins, proteases and other virulence factors to overcome host immune system and successfully establish the infection. Although lectins with their carbohydrate-binding abilities are not the typical example of molecules causing direct damage to host organism, they are indispensable in the processes such as attachment to cells, immunoevasion and immunosuppression. Bacteria of the genus Photorhabdus are not an exception as they produce lectins that could help them to interact with nematode symbionts, other bacteria or host immune system. Recently, we focused on lectins produced by P. laumondii (formerly classified as P. luminescens subsp. laumondii) that are not only able to bind to insect haemocytes, but also to disturb cellular and humoral immune response. Lectin treatment of insect haemolymph induced melanisation catalysed by phenoloxidase; this increase was not observed when we used the lectin pre-treated with saccharides selected according to its specificity. Although, P. laumondii is not considered to be human pathogen (unlike closely related P. asymbiotica), its lectin is able to inhibit production of reactive oxygen species in human blood induced by neutrophil activator zymosan A, whereas it is not able to supress the action of other activators such as phorbol 12-myristate 13-acetate or fMLF. Our results suggest that the lectin interferes with Toll-like receptor 2 and thus can impair the production of reactive oxygen species by host phagocytes. The work was supported by the Czech Science Foundation (grants no. 17-03253S and 18-18964S).