Lipoteichoic acid and molecular weight of hyaluronic acid could explain the late inflammatory response trigger by hyaluronic acid fillers

Abstract Introduction Hyaluronic acid is a safe dermal filler, but sometimes late granuloma is generated. This adverse effect is an inflammatory process, and its causes are not clear. Late granuloma generation could be due to the reaction to residual components of the bacterial wall present into hyaluronic acid, such as lipoteichoic acid (LTA). Other possibility is hyaluronic acid degraded could be trigger this inflammatory reaction. Objective Study possible molecular mechanism that could be implicated into the late granuloma formation. We wonder whereas inflammatory response activation is triggered by lower molecular weight hyaluronic acid or Gram‐positive bacterial components as LTA. Methods We analyzed one adverse case generated by hyaluronic acid injections. Our study with one nodule through chemical and immunofluorescence histologic technics. Results In this case, observe a late granuloma without infectious process. Histological analysis shown few large Langerhans cells around fillers and multiple immunological cells infiltrated. Immunofluorescent study shown immunological cells (CD45 positives cells) with high TLR2 expression (hyaluronic acid and LTA receptor). Limitations The difficulty of obtaining biopsy samples of nodules implies that the number of cases analyzed is very low. Conclusion New model is proposed in which weight of hyaluronic acid and LTA could be able to trigger inflammation. This process could be mediated by TLR2 expressed in infiltrated immune cells.