Acute inflammation triggered by two lightweight hernia meshes: a comparative in vitro and retrospective cohort study.

PURPOSE: Retro-muscular mesh augmentation is standard for repairing abdominal incisional or larger primary hernia. A wide variety of meshes with diverse properties are available. The knowledge on the immune-modulating effects of meshes is, however, insufficient. This study investigates the impact of two widely used lightweight meshes, ULTRAPRO(®) and ProGrip™, on macrophage activation (in vitro), systemic inflammation (in vivo), patient perioperative and long-term outcomes. METHODS: Human THP-1 cell-derived macrophages were cultured in absence and presence of ULTRAPRO(®) or ProGrip™ meshes. The release of pro-inflammatory cytokines, interleukin (IL)-1β and IL-6, was measured following inflammasome activation. In a retrospective study, systemic inflammation and postoperative outcomes after retro-muscular hernia repair using ULTRAPRO(®) (321 patients) or ProGrip™ (161 patients) meshes were analyzed. RESULTS: In the presence of ULTRAPRO(®), IL-1β and IL-6 release by macrophages was increased, whereas ProGrip™ tended to reduce cytokine levels (p ≤ 0.05; n = 7). Baseline characteristics were comparable between both groups; systemic C-reactive protein levels were likewise higher in patients receiving ULTRAPRO(®) compared to ProGrip™ (mean difference: 26.9 ± 7.5 mg/dl; p < 0.0001). No relevant differences were observed in perioperative morbidity or short-term outcomes, including complications and hospitalization after hernia repair, but hernia recurrence rates tended to be higher within three-year follow-up after ProGrip™ implantation compared to ULTRAPRO(®) (p = 0.0630). CONCLUSION: Meshes exhibit distinct immune-modulating effects on macrophages, leading to differential activation that may influence foreign-body reaction and systemic inflammation. These immune responses potentially impact clinical outcomes and recurrence after hernia repair. This study underscores the need for comparative prospective, randomized-controlled trials to further evaluate the clinical relevance of mesh-specific immunological effects.