B cells expressing IL-10 mRNA modulate memory T cells after DNA-Hsp65 immunization

Abstract

In DNA vaccines, the gene of interest is cloned into a bacterial plasmid that is engineered to induce protein production for long periods in eukaryotic cells. Previous research has shown that the intramuscular immunization of BALB/c mice with a naked plasmid DNA fragment encoding the Mycobacterium leprae 65-kDa heat-shock protein (pcDNA3-Hsp65) induces protection against M. tuberculosis challenge. A key stage in the protective immune response after immunization is the generation of memory T cells. Previously, we have shown that B cells capture plasmid DNA-Hsp65 and thereby modulate the formation of CD8 + memory T cells after M. tuberculosis challenge in mice. Therefore, clarifying how B cells act as part of the protective immune response after DNA immunization is important for the development of more-effective vaccines. The aim of this study was to investigate the mechanisms by which B cells modulate memory T cells after DNA-Hsp65 immunization. C57BL/6 and BKO mice were injected three times, at 15-day intervals, with 100 mg naked pcDNA-Hsp65 per mouse. Thirty days after immunization, the percentages of effector memory T (TEM) cells (CD4 + and CD8 + /CD44 high /CD62L low ) and memory CD8 + T cells (CD8 + /CD44 high /CD62L low /CD127 + ) were measured with flow cytometry. Interferon g, interleukin 12 (IL-12), and IL-10 mRNAs were also quantified in whole spleen cells and purified B cells (CD43 -) with real-time qPCR. Our data suggest that a B-cell subpopulation expressing IL-10 downregulated proinflammatory cytokine expression in the spleen, increasing the survival of CD4 + TEM cells and CD8 + TEM/CD127 + cells.

Hsp65-Producing Lactococcocus lactis Prevents Antigen-Induced Arthritis in Mice

“…It is not yet established the exact relationship between regulatory B cells and production of pathogenic antibodies. Immunization with M. leprae DNA-Hsp65 induced a B-cell subpopulation expressing IL-10 ( 45 ). These B regulatory cells (B reg ) were inversely associated with symptoms in rheumatic patients ( 42 ).…”

pVAXhsp65 Vaccination Primes for High IL-10 Production and Decreases Experimental Encephalomyelitis Severity

“…Many reports have also highlighted the role of hsp60/65 in activation of B cells [ 49 ], T cells [ 50 ], Treg cells [ 51 ], and maturation of dendritic cells [ 52 ]. Specially concerning hsp65 formulated as a DNA vaccine, Fontoura et al, 2015 [ 53 ], described that DNAhsp65 immunization of C57BL/6 mice induced a subtype of IL-10 producing B cell able to reduce the production of proinflammatory cytokine mRNAs in the spleen. Hsp65 was also able to attenuate the development of airway hyperresponsiveness and inflammation in BALB/c mice through modulation of dendritic cell function [ 54 ].…”

Immunotherapeutic Activities of a DNA Plasmid Carrying the Mycobacterial hsp65 Gene (DNAhsp65)

“…Aimed at developing an effective vaccine against TB, some authors also focused on identifying the role of B lymphocytes in the protection exhibited by DNAhsp65 ( 46 , 47 ). Exercising their function as APCs, B cells incorporate the plasmid DNA and modulate the cytotoxic memory response after Mtb challenge ( 46 ). The mechanisms involved in this modulation were subsequently investigated.…”