Probing the immunomodulatory activity of Sphagnum spp. from Irish boglands

Sphagnum species are mosses of the bryophyte taxonomic division, widely distributed in the Northern Hemisphere in wetland areas where accumulation of Sphagnum material forms peat bog habitats. In this study, we probed the in vitro immunomodulatory activities of methanolic extracts of Sphagnum spp . collected from raised bogland in county Offaly in the midlands of Ireland. Extracts of eight species were prepared by Soxhlet extraction and screened for immunomodulatory effects on lipopolysaccharide (LPS)-induced cytokine release in phorbol 12-myristate 13-acetate differentiated THP-1 cells. All Sphagnum spp. extracts tested significantly reduced the release of IL-6 and RANTES on stimulation, with complete attenuation of IL-6 by S. capillifolium and S. papillosum at 100 μg/mL. These species extracts also demonstrated the most significant attenuation of RANTES observed. There was a trend to reduction of IL-1β release by all treatments, S. capillifolium and S. papillosum again showing the most significant effects. In ELISA of TNF, pro-inflammatory effects were observed, with some treatments inducing significant TNF release in comparison to DMSO vehicle treated cells in the absence of LPS but TNF release induced by LPS was significantly reduced by the S. capillifolium and S. papillosum treatments. LPS triggers an immune response predominantly by binding Toll-like receptor 4 (TLR4) activating intracellular signalling cascades. Western blot analysis showed that S. capillifolium and S. papillosum treatments suppressed LPS-induced phosphorylation of both NF-κB and JNK but not p38. The immunomodulatory effects of these extracts warrant further investigation and delineation of the contributing fractions, constituent or combination of constituents is underway. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany