A polymer coating applied to Salmonella prevents the binding of Salmonella-specific antibodies

Area of Science:

• Oncolytic bacteria
• Immunomodulation
• Biomaterials

Background:

• Salmonella exhibits potential as an antitumor agent.
• Innate immunity limits Salmonella's efficacy in targeting tumors and antitumor activity.
• Pre-existing immune responses can hinder the effectiveness of Salmonella-based therapies.

Purpose of the Study:

• To investigate modulating the tumor-targeting efficiency of Salmonella enterica serovar choleraesuis.
• To assess the impact of poly(allylamine hydrochloride) (PAH) coating on Salmonella immune evasion.
• To evaluate the antitumor activity of PAH-coated Salmonella (PAH-S.C.) in the context of pre-existing immunity.

Main Methods:

• Coating Salmonella enterica serovar choleraesuis with poly(allylamine hydrochloride) (PAH) to create PAH-S.C.
• Utilizing naïve and Salmonella-immunized mice models.
• Assessing Salmonella invasion, cytotoxicity, and gene transfer in vitro and in vivo.
• Analyzing tumor growth, survival rates, and immune cell infiltration (neutrophils, macrophages) via immunohistochemistry.

Main Results:

• Anti-Salmonella antibodies significantly reduced Salmonella's invasion, cytotoxicity, and gene transfer capabilities.
• PAH-S.C. treatment demonstrated delayed tumor growth and enhanced survival in immunized mice.
• Immunohistochemical analysis revealed increased neutrophil and macrophage infiltration in tumors of immunized mice treated with PAH-S.C.

Conclusions:

• Salmonella encapsulation with PAH effectively circumvents Salmonella-specific immune responses.
• PAH-S.C. demonstrates therapeutic potential by overcoming pre-existing immunity against Salmonella.
• This approach offers a strategy to enhance the efficacy of oncolytic Salmonella therapies.