Immunomodulatory Properties of the Cyclic Lipopeptide Surfactin

Surfactin is a cyclic lipopeptide biosurfactant produced by Bacillus species that has attracted increasing attention due to its potent immunomodulatory and anti-inflammatory activities. Beyond its well-established surface-active properties, accumulating evidence has demonstrated that surfactin modulates key inflammatory and stress-responsive signaling pathways, including NF-κB, MAPKs, inflammasomes, oxidative stress, and mitochondrial function, across diverse biological systems. These effects translate into protective roles in models of inflammatory, metabolic, microbial, and neuroimmune disorders. However, the biological activity of surfactin is highly context-dependent. Its amphiphilic, membrane-active nature underlies both therapeutic efficacy and dose-limiting toxicity, particularly at higher concentrations or in immune-primed environments. Moreover, variability across studies is strongly influenced by isoform composition, strain-specific biosynthesis, formulation, and potential microbial contaminants, complicating cross-study comparisons and mechanistic interpretation. Toxicological evaluations indicate a favorable safety profile at moderate doses, yet underscore the need for precise dose control and standardized preparations. Recent advances in microbial engineering have enabled isoform-selective biosynthesis and substantially improved production yields. Formulation strategies, including nanoparticle-based delivery, have enhanced stability, reduced cytotoxicity, and expanded therapeutic windows. This review integrates current knowledge of surfactin's immunological mechanisms, safety considerations, and biotechnological innovations, highlighting critical challenges and opportunities for translation. Collectively, surfactin can be regarded as a tunable molecular platform whose immunological behavior can be modulated through structural control, formulation strategies, and process engineering, thereby supporting its development as a safe and effective therapeutic agent for inflammatory and immune-mediated diseases.