Lactic acid improves Treg manufacturing and in vivo function

Area of Science:

• Immunology
• Cell Therapy
• Biochemistry

Background:

• Adoptive cell therapy using regulatory T cells (Tregs) shows promise for autoimmunity and transplantation.
• Expanding pure and highly suppressive Tregs remains a significant challenge in cell therapy development.
• Lactic acid (LA) is known to enhance Treg function in tumor microenvironments.

Purpose of the Study:

• To investigate the potential benefits of lactic acid (LA) during the expansion of regulatory T cells (Tregs).
• To determine if LA improves Treg purity, viability, suppressive function, and reduces exhaustion markers.
• To evaluate the efficacy of LA-conditioned Tregs in preclinical models of immune-mediated diseases.

Main Methods:

• Human polyclonal and chimeric antigen receptor (CAR)-Tregs were expanded with or without lactic acid (LA).
• Treg viability, purity, glycolysis, and suppressive function were assessed post-expansion and upon re-stimulation.
• Expression of exhaustion markers (PD-1, TIM-3, LAG-3, TOX, BLIMP-1) was analyzed in CAR-Tregs.
• LA-conditioned Tregs were tested in immunodeficient mouse models of chronic stimulation and xenogeneic graft-versus-host disease.

Main Results:

• Addition of LA from day 3 onwards significantly improved Treg viability and purity.
• LA enhanced Treg glycolysis upon re-stimulation and led to superior suppressive function.
• In CAR-Tregs, LA reduced tonic signaling-associated expression of exhaustion markers.
• LA-conditioned Tregs showed enhanced stability, reduced exhaustion, and improved efficacy in mouse models.

Conclusions:

• Lactic acid (LA) has a multimodal beneficial effect on human Treg expansion and function for cell therapy.
• LA improves Treg purity, viability, and suppressive capacity, while mitigating exhaustion.
• LA represents a novel method for generating an optimal Treg product for therapeutic applications in autoimmunity and transplantation.