Hsp65-producing Lactococcus lactis inhibits experimental autoimmune encephalomyelitis by preventing cell migration into spinal cord.

Multiple sclerosis is an autoimmune disease that affects the central nervous system. Because of its complexity and the difficulty to treat, searching for immunoregulatory responses that reduce the clinical signs of disease by non-aggressive mechanisms and without adverse effects is a scientific challenge. Herein we propose a protocol of oral tolerance induction that prevented and controlled MOG-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. The genetically modified strain HSP65-producing Lactococcus lactis was orally administered for 5 consecutive days either before or during disease development in mice. Both protocols of feeding HSP65 resulted in significant reduction in the clinical score of EAE. Frequencies of LAP+CD4+Foxp3- regulatory T cells were higher in spleens and inguinal lymph nodes of fed mice. In addition, intravital microscopy showed that adherence of leukocytes to venules in the spinal cord was reduced in orally treated mice. Oral treatment with HSP65-producing L.lactis prevented leukocytes to leave the secondary lymphoid organs, therefore they could not reach the central nervous system. Despite the inhibition of pathological immune response that drive EAE development, activated T cells were at normal frequencies suggesting that oral tolerance did not induce general immunosuppression, but it led to specific control of pathogenic T cells. Our results indicate a novel therapeutic strategy to prevent and control autoimmune diseases such as multiple sclerosis.

Vitamin A supplementation leads to increases in regulatory CD4+Foxp3+LAP+ T cells in mice.

Dietary compounds, including micronutrients such as vitamin A and its metabolite retinoic acid, directly influence the development and function of the immune system. In this study, we show that either dietary deficiency of or supplementation with vitamin A had immunologic effects in mice that were fed these diets during their development (for 8 wk during the postweaning period). Deficient mice presented higher levels of interferon-γ, interleukin (IL)-6, transforming growth factor-ß, IL-17, and IL-10 in the gut-associated lymphoid tissues and draining lymph nodes, indicating a proinflammatory shift in the gut mucosa. Serum immunoglobulin G levels also were elevated in these mice. Conversely, supplemented mice showed higher frequencies of CD4+Foxp3+LAP+ regulatory T cells in gut lymphoid tissues and spleen, suggesting that vitamin A supplementation in the diet may be beneficial in pathologic situations such as inflammatory bowel diseases.

Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells.

Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-ß - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice.