Abstract
Background
Engineered bacterial therapeutics represent a promising strategy for sustained intestinal delivery of therapeutic molecules, but their efficacy is limited by inefficient colonisation, safety concerns and the need for repeated administration or auxiliary delivery systems.
Objective
To develop a safety-optimised native bacterial chassis capable of long-term gut colonisation and sustained therapeutic delivery for intestinal inflammatory and metabolic diseases.
Design
Native murine
Escherichia coli
isolates were screened for antibiotic susceptibility, genetic tractability and long-term intestinal colonisation. The selected strain, MEc30, was further optimised by deleting the putative virulence-associated
clb
and
irp
loci. MEc30 was then engineered to produce nicotinic acid (MEc30-NA) or deliver murine interleukin-10 (MEc30-mIL-10), and therapeutic efficacy was evaluated in a high-fat diet-induced metabolic dysfunction model as well as
Il10
−/−
and dextran sulphate sodium (DSS)-induced colitis models.
Results
MEc30 achieved stable lifelong colonisation of the murine intestine after a single oral administration, without antibiotic preconditioning or auxiliary delivery systems and did not detectably disturb host physiology or gut microbial ecology. Deletion of
clb
and
irp
abolished potential colibactin- and yersiniabactin-associated biosafety risks while preserving bacterial growth and colonisation capacity. MEc30-NA continuously produced nicotinic acid in the gut, activated epithelial GPR109a-associated barrier signalling, improved glucose and lipid metabolism, reduced systemic inflammation and avoided the sharp peak exposure associated with conventional nicotinic acid administration. MEc30-mIL-10 enabled sustained intestinal interleukin-10 delivery, suppressed inflammatory macrophage activation, improved barrier integrity and alleviated colitis in both
Il10
−
/
−
and DSS-induced mouse models.
Conclusion
This study identifies MEc30 as a durable and safety-optimised native
E. coli
chassis for sustained intestinal therapeutic delivery. Engineered native symbionts may provide a long-acting live biotherapeutic strategy for metabolic diseases and chronic intestinal inflammation.