The Effect of Orally Administering Forkhead Box P3 Recombinant Lactobacillus plantarum on Regulatory T-cell Functionality in a Humanized Mouse Model for Rheumatoid Arthritis: A Research Protocol

Introduction: Inflammation and joint stiffening are common symptoms of rheumatoid arthritis (RA), an autoimmune inflammatory disease. Previous treatments of RA have focused on decreasing symptomatic effects but have limited effects on disease progression. In RA, an influx of pro-inflammatory cytokines occurs at the synovium, which is the soft tissue surrounding the joints. The production of pro-inflammatory cytokines is controlled by regulatory T-cells, which have a deficit in function in RA patients. Regulatory T-cell development and function is regulated by the forkhead box P3 (FOXP3). The FOXP3 gene is a viable therapeutic target to restore regulatory T-cell functionality because FOXP3 is underexpressed in RA patients. Therefore, this study ventures to treat RA regulatory T-cell functionality by increasing FOXP3 gene expression through FOXP3 recombinant Lactobacillus plantarum bactofection. We hypothesize that bactofection will lead to a decrease in RA progression by restoring normal function in regulatory T-cells, thus decreasing inflammation. Methods: We propose a study using severe combined immunodeficient mouse models engrafted with human RA synovium. The mice will be given either no treatment (control group) or a 2×109 CFU/g dose of recombinant Lactobacillus plantarum strain. The mice will be sacrificed after 0 days, 10 days, 20 days, and 30 days (control group and treatment groups respectively). Synovial tissue samples will be obtained from the hip joints. Through immunofluorescence and western blotting, the prevalence of FOXP3, regulatory T-cells and pro-inflammatory cytokines such as tumor necrosis factor-alpha, Interleukin-1 and Interleukin-6 will be compared between the control and treatment groups. For statistical analysis, a one-way MANOVA test, Levene’s test, and a Shapiro-Wilk test will be performed using GraphPad Prism. Results: As a result of bactofection, there will be an increase in FOXP3 and regulatory T-cells, resulting in a decrease of pro-inflammatory cytokines. Discussion: Analysis of mice treated with recombinant Lactobacillus plantarum compared to mice with no treatment will set a correlation between FOXP3, regulatory T-cells, and pro-inflammatory cytokines prevalence and RA progression after treatment. Conclusion: The findings of this study will provide evidence that bactofection is a viable treatment for RA, and may be more effective than conventional treatments.