We successfully obtained an ammonia oxidizing archaeon of the genus Nitrosocosmicus in pure laboratory culture. ‘Nitrososcosmicus epidermidis’ is the first AOA isolated from human skin and prefers conditions that are relevant for growth on human skin including growth on surfaces as a biofilm, a temperature optimum of 29°C, and the ability to grow under high concentrations of ammonia or urea, as it occurs in human sweat.
The potential of this strain for wound healing and its effects on immune cells was tested. Only, N. epidermidis (and not other related archaea) led to a reproducible transient and dose-dependent increase of pro-inflammatory cytokines, mainly connected with innate immunity on murine and human macrophages. In addition we got promising indications in CAM assays for the potential of vasculogenesis important for chronic wounds, since these environments typically suffer from decreased perfusion and thereby decreased nutrient and oxygen flow and an impaired immune system. Both findings indicate a general potential for the application of skin archaea in wound healing which need to be further explored. Cell depletion assays using primary human fibroblasts, however, did not yet show significant results and need further optimization.
In addition we identified a second, anaerobic archaeon to be able to accumulate in tumor spheroids of colon and breat cancer lines. The archaea were detected via fluorescent labels and PCR and persisted for at least a week. The cells were also found in initial in vivo experiments to perform tumor homing. Subsequently, a novel, proprietary strain of the same genus was isolated which showed the same performance.
While bacterial ghosts induce activation of toll-like receptors, no such activation was observed with the archaeal strain. Hence, archaea are superior over other bacterial vectors, which have already been used for tumor targeting. This finding will be the foundation for a new project to harness these archaea for tumor treatment, either as a direct antitumoral compound, where they interact with the metabolome of the tumor, or as targeted carrier system.
