We examined the role of Th2 cytokines, namely IL-4 and IL-10, in the protective effect of OM-85. Using genetically deficient mice and cytokine-neutralizing monoclonal antibodies, we have demonstrated that the therapeutic effect does not involve the Th2 cytokine IL-4 but is tightly dependent upon transforming growth factor (TGF)-β. Natural killer (NK) T cells also participate in the therapeutic effect, as CD1d−/− NOD mice Lenvatinib solubility dmso are partially resistant to the protective effect of OM-85 [45]. Importantly, key mechanistic

results were that OM-85 induced the production of IL-12 by DCs and of IL-10 essentially by B lymphocytes. It is important to stress at this point that there appears to be a tight dependency between the TGF-β-producing ability of OM-85 and the protective effect on the disease, find more because when a neutralizing anti-TGF-β antibody was administered immediately after OM-85, the protective effect of the drug was lost [45]. The second important finding was that, in spite of the fact that OM-85 is a mixture of several bacterial products, its protective effect on diabetes development appears to be mediated by components targeting TLR-4 [45]. Supporting this conclusion further are the recent data we obtained using in vivo instead of the intact bacterial extract:

well-defined TLR-4 ligands OM-174-DP and OM-197-MP-AC that are currently under clinical development as adjuvants [46–50]. These are mimics of the lipid A portion of lipopolysaccharide (LPS), possessing many of the biological activities of LPS but devoid of its toxic effects [46,48,50]. OM-174-DP

and OM-197-MP-AC protected NOD mice significantly from the development of diabetes, similarly to G protein-coupled receptor kinase OM-85. As with OM-85 the therapeutic activity correlated with an effect on B lymphocytes, leading to their proliferation and IL-10 secretion. The immunopharmacology of TLR ligands is just at its beginning, but the results appear encouraging enough to invest in this novel immune intervention avenue. None of the authors has conflicts of interest to declare, or any relevant financial interest, in any company or institution that might benefit from this publication. “
“Haematopoietic humanization of mice is used frequently to study the human immune system and its reaction upon experimental intervention. Immunocompromised non-obese diabetic (NOD)-Rag1–/– mice, additionally deficient for the common gamma chain of cytokine receptors (γc) (NOD-Rag1–/– γc–/– mice), lack B, T and natural killer (NK) cells and allow for efficient human peripheral mononuclear cell (PBMC) engraftment. However, a major experimental drawback for studies using these mice is the rapid onset of graft-versus-host disease (GVHD).