In vivo anti-inflammatory and antioxidant effects of microbial polysaccharides extracted from Euganean therapeutic muds.

Therapeutic thermal mud produced by spas of the Euganean Thermal District (Italy) is used as a treatment for arthro-rheumatic diseases. Its production involves the growth of a specific microbiota embedded in a polysaccharidic matrix. Polysaccharides (Microbial-PolySaccharides, M-PS) released in the mud by the resident microorganisms were extracted and analyzed. The monosaccharidic composition analysis showed the presence of galacturonic acid, mannose, xylose, ribose and glucose and a high percentage of sulfated groups in the polymers. To assess their involvement in the therapeutic efficacy of the mud, the M-PS were tested using the model organism zebrafish (Danio rerio). The anti-inflammatory and antioxidant activities were evaluated after confirming the lack of toxic effects during development. Inflammatory state was induced chemically with copper sulfate, or through tail fin amputation procedure and UVB exposure. Recovery from inflammatory condition after exposure to M-PS was always observed with specific morphometric analyses, and further supported by qPCR. Genes linked with the inflammatory and oxidative stress response were investigated confirming the M-PS treatment's efficacy.

Microbiota of the Therapeutic Euganean Thermal Muds with a Focus on the Main Cyanobacteria Species.

The Euganean Thermal District has been known since Roman times for the therapeutic properties of peloids, obtained from natural clays that have undergone a traditional maturation process. This leads to the growth of a green microbial biofilm with Cyanobacteria and the target species Phormidium sp. ETS-05 as fundamental components for their ability to synthetize anti-inflammatory molecules. Currently, in-depth studies on the microbiota colonizing Euganean peloids, as in general on peloids utilized worldwide, are missing. This is the first characterization of the microbial community of Euganean thermal muds, also investigating the effects of environmental factors on its composition. We analysed 53 muds from 29 sites (Spas) using a polyphasic approach, finding a stable microbiota peculiar to the area. Differences among mud samples mainly depended on two parameters: water temperature and shading of mud maturation plants. In the range 37-47 °C and in the case of irradiance attenuation due to the presence of protective roofs, a statistically significant higher mud Chl a content was detected. Moreover, in these conditions, a characteristic microbial and Cyanobacteria population composition dominated by Phormidium sp. ETS-05 was observed. We also obtained the complete genome sequence of this target species using a mixed sequencing approach based on Illumina and Nanopore sequencing.

Anti-Inflammatory Activity of Exopolysaccharides from Phormidium sp. ETS05, the Most Abundant Cyanobacterium of the Therapeutic Euganean Thermal Muds, Using the Zebrafish Model.

The Euganean Thermal District (Italy) represents the oldest and largest thermal center in Europe, and its therapeutic mud is considered a unique product whose beneficial effects have been documented since Ancient Roman times. Mud properties depend on the heat and electrolytes of the thermal water, as well as on the bioactive molecules produced by its biotic component, mainly represented by cyanobacteria. The investigation of the healing effects of compounds produced by the Euganean cyanobacteria represents an important goal for scientific validation of Euganean mud therapies and for the discovering of new health beneficial biomolecules. In this work, we evaluated the therapeutic potential of exopolysaccharides (EPS) produced by Phormidium sp. ETS05, the most abundant cyanobacterium of the Euganean mud. Specifically, Phormidium EPS resulted in exerting anti-inflammatory and pro-resolution activities in chemical and injury-induced zebrafish inflammation models as demonstrated using specific transgenic zebrafish lines and morphometric and expression analyses. Moreover, in vivo and in vitro tests showed no toxicity at all for the EPS concentrations tested. The results suggest that these EPS, with their combined anti-inflammatory and pro-resolution activities, could be one of the most important therapeutic molecules present in the Euganean mud and confirm the potential of these treatments for chronic inflammatory disease recovery.