Pectin coating of titanium and polystyrene surfaces modulates the macrophage inflammatory response

Titanium has been used with success for bone anchoring of dental implants. However, when implant surfaces are exposed to the oral environment, the progression of peri-implantitis triggered by specific oral bacteria has been reported. Bacterial colonization of implants leads to prolonged immune cell activation and bone resorption. A new strategy to improve implant biocompatibility and prevent peri-implantitis is to develop pectin surface nanocoatings. These plant-derived polysaccharides are promising candidates for surface nanocoatings of titanium implants due to their osteogenic and anti-inflammatory properties. Therefore, the aim of the study was to evaluate the in vitro effect of nanocoating with plant-derived rhamnogalacturonan-I (RG-I) on pro- and anti-inflammatory responses of primary human monocyte-derived macrophages (HMDMs) induced by Escherichia coli LPS and Porphyromonas gingivalis bacteria. In the present study, two different types of surface materials, tissue culture polystyrene (TCPS) plates and titanium (Ti) discs, coated with pectic polysaccharides, potato unmodified RG-I (PU) and potato dearabinanated RG-I (PA), have been examined. The inflammatory responses of HMDMs after E. coli LPS/P. gingivalis stimulation were investigated through gene expression measurements of pro- and anti-inflammatory cytokines. The results showed that PU and PA decreased expression of the proinflammatory genes tumour necrosis factor-alpha (TNFA), interleukin-1 beta (IL1B) and interleukin-8 (IL8) in activated HMDMs cultured on TCPS/Ti surfaces. In contrast, the effects on anti-inflammatory interleukin-10 (IL10) gene expression were not significant. The results indicate that RG-Is should be considered as a candidate for organic nanocoatings of titanium implant surfaces in order to limit host proinflammatory responses and improve bone healing.