Targeting IL-6 by engineered Lactococcus lactis via surface-displayed affibody.

Area of Science:

• Microbiology
• Immunology
• Biotechnology

Background:

• Dysregulated interleukin-6 (IL-6) production is linked to inflammatory bowel disease (IBD) pathology.
• Neutralizing IL-6 within the gut using probiotic bacteria offers a potential therapeutic strategy for intestinal inflammation.

Purpose of the Study:

• To develop Lactococcus lactis engineered to display a potent and selective IL-6-binding affibody on its surface.
• To evaluate the efficacy of these engineered bacteria in sequestering IL-6 from various environments.

Main Methods:

• Surface display of an anti-IL-6 affibody (ZIL) on Lactococcus lactis using secretion and anchoring proteins.
• Validation of ZIL expression and functionality via confocal microscopy and flow cytometry.
• Quantification of IL-6 removal using enzyme-linked immunosorbent assay (ELISA) and assessment in cell culture supernatants.

Main Results:

• Engineered L. lactis successfully displayed the ZIL fusion protein on its surface.
• ZIL-displaying L. lactis demonstrated high specificity for IL-6, removing up to 99% of recombinant human IL-6 from solution.
• The bacteria effectively reduced IL-6 levels in supernatants from immunostimulated human monocytic cell lines (THP-1 and U-937) by up to 94%.

Conclusions:

• The engineered L. lactis efficiently binds and removes pathologically relevant concentrations of IL-6.
• The demonstrated ability to neutralize IL-6 at common bacterial doses suggests significant physiological relevance for IBD treatment.