No association found between late-onset inflammatory adverse events after soft tissue filler injections and the adaptive immune system

Etiology of Delayed Inflammatory Reaction Induced by Hyaluronic Acid Filler

The etiology and pathophysiology of delayed inflammatory reactions caused by hyaluronic acid fillers have not yet been elucidated. Previous studies have suggested that the etiology can be attributed to the hyaluronic acid filler itself, patient's immunological status, infection, and injection technique. Hyaluronic acid fillers are composed of high-molecular weight hyaluronic acids that are chemically cross-linked using substances such as 1,4-butanediol diglycidyl ether (BDDE). The mechanism by which BDDE cross-links the two hyaluronic acid disaccharides is still unclear and it may exist as a fully reacted cross-linker, pendant cross-linker, deactivated cross-linker, and residual cross-linker. The hyaluronic acid filler also contains impurities such as silicone oil and aluminum during the manufacturing process. Impurities can induce a foreign body reaction when the hyaluronic acid filler is injected into the body. Aseptic hyaluronic acid filler injections should be performed while considering the possibility of biofilm formation or delayed inflammatory reaction. Delayed inflammatory reactions tend to occur when patients experience flu-like illnesses; thus, the patient's immunological status plays an important role in delayed inflammatory reactions. Large-bolus hyaluronic acid filler injections can induce foreign body reactions and carry a relatively high risk of granuloma formation.

Hyaluronic Acid Fillers and ASIA Syndrome: Case Studies

A continuous increase in the popularity of esthetic procedures with the use of substances as HA has been observed for many years, which might be contributing to an increase in the number of adverse events. The autoimmune/inflammatory syndrome induced by adjuvants (ASIA) can be provoked by hyaluronic acid (HA), which belongs to substances meeting the criteria of adjuvants. Mechanisms of the innate and acquired immune response are activated, leading to the dysregulation of T and B lymphocytes, inability to recognize one's own antigens, inflammation, damage to one's own tissues, and ultimately to autoimmunity. The objective of this article is to present a case-series study of patients who developed ASIA syndrome following HA injection after delayed inflammatory reaction (DIR) and emphasize the importance of the need for long-term monitoring after such the reaction. Lack of knowledge about ASIA can lead to delayed diagnosis and serious consequences for the patients. People with a history of immunization reactions, severe allergic reactions, individual predisposition to autoimmunity or family predisposition to autoimmunity and previous exposure to adjuvants require special attention and long-term follow-up. This applies primarily to cases of DIR after the using of bioimplants, especially with treatment resistance, as in our reported cases.