A groundbreaking study by Professor Ki Hyun Kim's research team from the School of Pharmacy at Sungkyunkwan University (President Ji-beom Yoo) and Professor Smita Gopinath's research team from Harvard T.H. Chan School of Public Health has revealed that Lactobacillus crispatus, a key species of vaginal lactobacilli, produces a family of anti-inflammatory compounds known as β-carbolines. These compounds play a crucial role in stabilizing the immune environment of the vagina. This discovery highlights the remarkable capacity of lactobacilli to not only serve as beneficial bacteria but also directly modulate human immune responses.

Among the β-carboline compounds identified using the bioactivity-guided isolation, perlolyrine emerged as the most notable. This compound effectively suppresses inflammatory signaling pathways, including NF-κB and type I IFN pathways, in immune and epithelial cells. Additionally, it significantly reduces the production of pro-inflammatory cytokines such as IL-1β and IL-6. In mouse experiments, perlolyrine demonstrated a potent anti-inflammatory effect, reducing inflammation by up to 77%.

Interestingly, these compounds were found in higher concentrations in the vaginal microbiomes of healthy individuals, while those with bacterial vaginosis (BV) exhibited significantly lower levels. This suggests that β-carbolines play a vital role in maintaining vaginal health and controlling inflammation. To validate the therapeutic potential of β-carbolines, the researchers conducted experiments using a mouse model of vaginal inflammation. The topical application of perlolyrine resulted in reduced inflammation and lower levels of inflammatory cytokines such as IL-1β and IL-18. The treatment also alleviated symptoms and improved survival rates without compromising the immune system’s natural antiviral response. Remarkably, the anti-inflammatory effects were sustained even during viral infections.

Professor Ki Hyun Kim stated that this study underscores the potential of β-carboline compounds as therapeutic agents for treating inflammation-related conditions such as vaginitis and bacterial vaginosis. These compounds are unique in their ability to suppress inflammation while preserving the natural immune defense mechanisms, paving the way for the development of innovative topical treatments. Moreover, the findings highlight the broader role of lactobacilli in restoring and maintaining a healthy vaginal microbiome. By leveraging the natural production of β-carbolines, the study provides a new perspective on developing probiotics and prebiotics aimed at improving vaginal health. The research team plans to further explore the therapeutic applications of β-carbolines, aiming to translate these findings into clinical solutions for inflammatory disorders. This pioneering work sheds light on the intricate interactions between human hosts and their microbiota, offering new opportunities to harness microbial products for health and wellness.

This study was conducted with support from the Ministry of Science and ICT and the National Research Foundation of Korea through the Basic Medical Science Research Center (MRC) program and the Mid-Career Researcher Program. The research findings were published online on November 13 in the international journal Cell Host & Microbe (IF: 20.6), ranked in the top 2% in the microbiology category and 1st in parasitology and virology according to JCR.

※ Title: Vaginal lactobacilli produce anti-inflammatory β-carboline compounds

※ Journal: Cell Host & Microbe(IF: 20.6)

※ Authors: Ki Hyun Kim (Corresponding Author), Seo Yoon Lee (Co-Author)

Figure 1. The schematic diagram for the discovery of anti-inflammatory β-carboline compounds and validation of their functional efficacy

Figure 2. Discovery of anti-inflammatory β-carboline compounds through bioactivity-guided isolation.

Figure 3. Validation of the anti-inflammatory activity of β-carboline compounds using a herpes virus-infected animal model.

Professor Ki Hyun Kim's research team