Host lysozyme-mediated lysis of Lactococcus lactis facilitates delivery of colitis-attenuating superoxide dismutase to inflamed colons.

Proc Natl Acad Sci U S A
Authors
Keywords
Abstract

Beneficial microbes that target molecules and pathways, such as oxidative stress, which can negatively affect both host and microbiota, may hold promise as an inflammatory bowel disease therapy. Prior work showed that a five-strain fermented milk product (FMP) improved colitis in T-bet(-/-) Rag2(-/-) mice. By varying the number of strains used in the FMP, we found that Lactococcus lactis I-1631 was sufficient to ameliorate colitis. Using comparative genomic analyses, we identified genes unique to L. lactis I-1631 involved in oxygen respiration. Respiration of oxygen results in reactive oxygen species (ROS) generation. Also, ROS are produced at high levels during intestinal inflammation and cause tissue damage. L. lactis I-1631 possesses genes encoding enzymes that detoxify ROS, such as superoxide dismutase (SodA). Thus, we hypothesized that lactococcal SodA played a role in attenuating colitis. Inactivation of the sodA gene abolished L. lactis I-1631's beneficial effect in the T-bet(-/-) Rag2(-/-) model. Similar effects were obtained in two additional colonic inflammation models, Il10(-/-) mice and dextran sulfate sodium-treated mice. Efforts to understand how a lipophobic superoxide anion (O2 (-)) can be detoxified by cytoplasmic lactoccocal SodA led to the finding that host antimicrobial-mediated lysis is a prerequisite for SodA release and SodA's extracytoplasmic O2 (-) scavenging. L. lactis I-1631 may represent a promising vehicle to deliver antioxidant, colitis-attenuating SodA to the inflamed intestinal mucosa, and host antimicrobials may play a critical role in mediating SodA's bioaccessibility.

Year of Publication
2015
Journal
Proc Natl Acad Sci U S A
Volume
112
Issue
25
Pages
7803-8
Date Published
2015 Jun 23
ISSN
1091-6490
URL
DOI
10.1073/pnas.1501897112
PubMed ID
26056274
PubMed Central ID
PMC4485081
Links
Grant list
K08 AI078942 / AI / NIAID NIH HHS / United States
R01 CA154426 / CA / NCI NIH HHS / United States
K08AI078942 / AI / NIAID NIH HHS / United States
R01CA154426 / CA / NCI NIH HHS / United States