Detection of Nontoxic BoNT/A Levels in Post-Facial Botox Injection Breastmilk using a Multi-technique Approach

Background The use of cosmetic Botox (Botulinum Neurotoxin Type A, BoNT/A ) has become increasingly prevalent. Particularly after pregnancy, postpartum depression represents one major factor motivating women to use Botox even during the lactation and breastfeeding period. Currently, there is limited understanding of the impact of Botox on lactation and the potential of its active component passing into breastmilk and affecting the infant. Methods Breastmilk samples were acquired from five women aged between 28 - 45 through a clinic in Suzhou, Jiangsu, P.R. China. Three sample sets ranged from 1 hour to 1 year after facial Botox treatments (64 U), whereas the remaining two sample sets were from women who never received Botox treatment. BoNT/A concentrations in samples were detected using standard Enzyme-Linked Immunosorbent Assay (ELISA), unreduced and reduced Western Blotting, confocal micro-Raman Spectroscopy, and Mass Spectrometry(LC-MS). Findings From ELISA, breastmilk BoNT/A concentrations peaked at 33.4 pg/mL 4 days after Botox injection. BoNT/A concentrations were highest overall in the first week and around two months after injection. While non-reducing polyacrylamide gel electrophoresis (PAGE) showed a protein band of 150 kDa peaking at 48 hours, reduced SDS-PAGE detected a 100 kDa protein first peaking at 72 hours, then re-emerging after 7 days, respectively, and in line with previous observations by others. Interestingly, micro-Raman spectroscopy indicated additional Raman peaks at 6 hours and 48 hours that were not present in other breastmilk samples which were evaluated in this study. However, no clear indication of BoNT/A was detected in Mass Spectrometry (LC-MS). Interpretation The amount of BoNT/A in breastmilk peaks around 48 hours, and at 2 months after facial injection. Even over a year after injection, BoNT/A can be detected. However, all quantities of BoNT/A detected in this study are highly likely to be safe for infants. Additionally, our study suggests that alternative methods, besides ELISA, may be utilized for the rapid detection of low concentrations of BoNT/A in body fluid samples. Funding Duke Kunshan University Start-Up funds, Duke Kunshan University Undergraduate Studies Signature Work Research Grant, Synear and Wang-Cai Biochemistry grants, and Kunshan Municipal Government research funding. Graphical Abstract Highlights BoNT/A was detected in the breastmilk of 3 women after facial Botox injections of 64 U. Toxin levels peaked in the first week and at around 2 months after injection. All detected levels (up to 33.40 pg/mL) were significantly below the lethal dose for newborns.