Construção e avaliação funcional de uma linhagem invasiva de Lactococcus lactis produtora da forma citoplasmática do antígeno Hsp65 de Mycobacterium leprae

Abstract

The intestinal mucosa has a complex immune system that is in homeostasis with the microbiota. However, the breaking of this balance may contribute to the development of inflammatory bowel diseases (IBDs), such as Crohn's disease (CD). CD is a multifactorial disease characterized by chronic, uncontrolled inflammation of the intestinal mucosa, and its occurrence is increasing worldwide, especially in developed countries. Its treatment is performed with steroids, immunomodulators and surgery, however, these are linked to serious side effects. Thus, there is a need to develop more effective treatments for patients that suffer from this disease. In this context, heat shock proteins, also known as HSPs, could be an interesting alternative. HSPs are chaperones important for the survival of cells and found in all forms of life. Additionally, HSP60 is an immunodominant antigen considered important in the regulation of effector T cells, with great potential in reducing Th1 and increasing Th2 and Treg responses, with such responses required for CD control. Therefore, the use of lactic acid bacteria, such as Lactococcus lactis, for the production and delivery of proteins with therapeutic potential, such as Hsp65, directly into the intestinal mucosa of the host cells may represent a novel strategy for the treatment of CD. In this study, it was built a novel invasive strain (L. lactis NCDO2118 FnBPA+) and an invasive strain capable of producing Mycobacterium leprae Hsp65 [L. lactis NCDO2118 FnBPA+ (pXYCYT:Hsp65)]. Both strains were able to invade eukaryotic cells more efficiently than the wild type strain (L. lactis NCDO2118). Moreover, the strain producing Hsp65 was able to satisfactorily produce the recombinant cytoplasmic protein. With respect to security, after intragastric administration of the invasive strains in Balb/C mice, they were not able to translocate through the intestinal lumen to other organs. Accordingly, L. lactis NCDO2118 FnBPA+ (pXYCYT:Hsp65) has great potential for the realization of therapeutic trials for the experimental CD.