Genetically Engineered Immunomodulatory Streptococcus thermophilus Strains Producing Antioxidant Enzymes Exhibit Enhanced Anti-Inflammatory Activities

Abstract

The aims of this study were to develop strains of lactic acid bacteria (LAB) having both immunomodulatory and antioxidant properties and to evaluate their anti-inflammatory effects both in vitro, in different cellular models, and in vivo, in a mouse model of colitis. Different Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains were cocultured with primary cultures of mononuclear cells. Analysis of the pro-and anti-inflammatory cytokines secreted by these cells after coincubation with candidate bacteria revealed that L. delbrueckii subsp. bulgaricus CRL 864 and S. thermophilus CRL 807 display the highest anti-inflammatory profiles in vitro. Moreover, these results were confirmed in vivo by the determination of the cytokine profiles in large intestine samples of mice fed with these strains. S. thermophilus CRL 807 was then transformed with two different plasmids harboring the genes encoding catalase (CAT) or superoxide dismutase (SOD) antioxidant enzymes, and the anti-inflammatory effects of recombinant streptococci were evaluated in a mouse model of colitis induced by trinitrobenzenesulfonic acid (TNBS). Our results showed a decrease in weight loss, lower liver microbial translocation, lower macroscopic and microscopic damage scores, and modulation of the cytokine production in the large intestines of mice treated with either CAT-or SOD-producing streptococci compared to those in mice treated with the wild-type strain or control mice without any treatment. Furthermore, the greatest anti-inflammatory activity was observed in mice receiving a mixture of both CAT-and SOD-producing streptococci. The addition of L. delbrueckii subsp. bulgaricus CRL 864 to this mixture did not improve their beneficial effects. These findings show that genetically engineering a candidate bacterium (e.g., S. thermophilus CRL 807) with intrinsic immunomodulatory properties by introducing a gene expressing an antioxidant enzyme enhances its anti-inflammatory activities.

Streptococcus thermophilus, an emerging and promising tool for heterologous expression: Advantages and future trends

“…Finally, recent work on S. thermophilus CRL807 recombinants that heterologously produce superoxide dismutase and/or catalase demonstrated their antiinflammatory potentials in vivo. These recombinants decreased the severity of the inflammation in mice, with less body weight loss, lower macroscopic and histological damage scores in the large intestine, and a decrease of bacterial translocation to liver, compared to the inflammation control (Del Carmen et al, 2014).…”

Evaluation of the biosafety of recombinant lactic acid bacteria designed to prevent and treat colitis

“…Previously, our group has demonstrated that recLAB were effective in the treatment and/or prevention of IBD in animal models after conferring them the capacity to produce anti-oxidant enzymes such as catalase (CAT) or superoxide dismutase (SOD) (de Moreno de LeBlanc et al, 2008;del Carmen et al, 2014a) or the anti-inflammatory cytokine IL-10 (del Carmen et al, , 2014b. Also, the effectiveness of recLAB for the local delivery of IL-10 DNA and the subsequent production of the cytokine by host cells has also been shown (del Pontes et al, 2012;Zurita-Turk et al, 2014).…”

“…Also, the effectiveness of recLAB for the local delivery of IL-10 DNA and the subsequent production of the cytokine by host cells has also been shown (del Pontes et al, 2012;Zurita-Turk et al, 2014). In these trials, the generation of the recLAB was performed using the progenitor strains Lactococcus lactis MG1363, the most commonly used LAB for genetic engineering (Gasson, 1983); L. lactis NCDO2118, a strain with innate immune modulating properties (Luerce et al, 2014) or Streptococcus thermophilus CRL 807, a strain selected for its innate anti-inflammatory properties (del Carmen et al, 2014a).…”

“…The mice in the control group received sterile non-fat milk without bacteria in drinking water under the same conditions as the groups evaluated. S. thermophilus CRL807 : CAT and S. thermophilus CRL807 : SOD were administered as a mix of both strain suspensions in a 1 : 1 ratio because it was reported that this mixture exerted an improved anti-inflammatory effect compared to the administration of each strain individually (del Carmen et al, 2014a). Under these conditions, 1Â10 9 c.f.u.…”

Targeting the Microbiome in Inflammatory Bowel Disease: Critical Evaluation of Current Concepts and Moving to New Horizons

“…A genetically modified strain of Lactobacillus casei , BL23 that was engineered to produce superoxide dismutase, had preventive efficacy in TNBS-induced colitis in a murine model [56]. Streptococcus thermophilus CRL 807, also engineered to produce superoxide dismutase, has anti-inflammatory properties too [57]. Recently, genetically modified Lactococcus lactis that secretes elafin (a human protease inhibitor) [58], or IL-27 (a cytokine with immunosuppressive effects) [59], was also shown to have anti-inflammatory effects in colitis models and is, therefore, a candidate for clinical trials.…”