Loratadine as an Anti-inflammatory Agent Against Clostridium difficile Toxin B

Area of Science:

• Microbiology
• Immunology
• Pharmacology

Background:

• Clostridium difficile infection (CDI) is a significant nosocomial infection caused by toxins A and B, leading to inflammation.
• Current CDI therapies face challenges with recurrence, cost, and safety.
• There is a need for novel, non-microbiological therapeutic strategies against CDI.

Purpose of the Study:

• To identify a safe, effective, and economical non-microbiological therapeutic approach for CDI.
• To explore actionable toxin B-dependent pathways in human peripheral blood mononuclear cells (PBMCs).

Main Methods:

• Utilized human PBMCs, colonic explants, and humanized mice models.
• Employed single-cell RNA profiling and high-throughput screening to identify therapeutic targets.
• Tested C. difficile strains VPI 10463 (Toxin A+B+) and ribotype 017 (Toxin A-B+).

Main Results:

• Loratadine, identified via screening, reversed toxin-mediated macrophage inflammatory protein (MIP)-1α expression in PBMCs.
• Oral loratadine inhibited toxin B-induced MIP-1α secretion in human colonic tissues and protected against CDI in mouse and hamster models.
• Loratadine treatment conferred anti-inflammatory effects and suppressed MIP-1α in humanized mice.

Conclusions:

• Loratadine demonstrates potential as a repurposed therapeutic agent for Clostridium difficile infection.
• This antihistamine may offer a novel strategy to optimize existing CDI treatments by targeting inflammatory pathways.
• Further development of loratadine could lead to improved CDI management with enhanced safety and economic benefits.