Immunomodulatory Effects of Oxylipin 10-HOME Produced by Biofilm Results in Host-Biofilm Interaction in Breast Implant Illness

Abstract

PURPOSE: The spread of biofilms on medical implants represents one of the principal triggers of persistent and chronic infections in clinical settings. Nearly 300,000 women annually have breast implant surgery in the United States, for reasons including post-mastectomy breast reconstruction, revision of prior augmentation/ reconstruction, cosmetic augmentation, and gender affirmation. There has been increased identification of patients experiencing a constellation of symptoms related to their implants termed as breast implant illness (BII). In this work, we report that bacterial biofilm associated with breast implant, metabolize fatty acid oleic acid present in the breast tissue milieu to oxylipins, one such oxylipin identified from this study is (E)-10-hydroxy-8-octadecenoic acid (10-HOME). We hypothesize that immunomodulatory effects of oxylipin 10-HOME produced by biofilm present on the implant could be a possible etiology for BII pathogenesis. METHOD: Implants, peri-prosthetic tissues and blood was collected from BII subjects (n=46) and two control groups, group I, (non-BII, n=34) patients with breast implants, no BII symptoms. Group II (normal tissue, n = 20), patients without an implant, whose breast tissue was removed due to surgical procedures. A questionnaire developed based on epidemiological studies on BII screened for the commonly reported symptoms associated with BII. Predictive variables included age, diabetes status, co-morbidities, type (smooth/textured) and duration of implant. Scanning electron microscopy (SEM), 16S rRNA (genomic) next generation sequencing (NGS) were used for bacterial biofilm identification. 10-HOME was quantitated through targeted and untargeted lipidomic analyses using LC-MS-MS. RNA-Seq analysis was performed on peri-prosthetic breast tissues. Flow cytometry and mass cytometry (CyToF) were conducted to investigate the role of immune cells. RESULTS: Bacterial biofilm was detected through SEM and 16SrRNA NGS. Bivariate analysis using cross-tabulation was performed between presence of biofilm and the study groups. Using the two-sample test of proportions with z-tests, Staphylococcus epidermidis colonization was observed to be higher in the BII group (73.33%) compared to non-BII group (16.67%, p=0.018) and the normal group (10%, p=0.036). The BII group was 2.4 times more likely to have S. epidermidis colonization compared to the non-BII group (Odds Ratio=2.4). Similarly, when comparing with normal group, the BII group was 3.4 times more likely to have S. epidermidis. Elevated levels of 10-HOME in BII compared to non-BII samples, (p<0.0001) were observed through mass spectrometry. Positive correlation was observed between bacterial abundance and concentration of 10-HOME in BII subjects (R2=0.88). RNA-Seq analysis on peri-prosthetic tissue and flow/ mass cytometry analyses from peripheral blood derived lymphocytes showed increased abundance of CD4+ Th1 cells. Th1 cells have been reported to be activated in auto-immune diseases. No significant difference was observed in the abundance of other Th subtypes (Th2, Th9 and Th22). Oxylipin 10-HOME polarized CD4+ naïve T cells to Th1 subtype in vitro. CONCLUSION: This study investigated the biofilm hypothesis of BII through a biofilm derived immunogenic metabolite. Through a systematic cause-effect based studies, the work shows activation of Th1 cells in presence of 10-HOME. The study provides the first evidence of a possible etiology of BII mediated via bacterial biofilm derived 10-HOME.