All centrifugation steps were performed at 4?C
All centrifugation steps were performed at 4?C. mice, and that anti-PD-1 and anti-PD-L1 treatment significantly increased IFN–producing CD4+ and CD8+ T cells, respectively. Compared with infection controls, mice treated with anti-PD-1 and anti-PD-L1, but not anti-PD-L2, displayed bigger lesions with significantly lower parasite loads. Treatment did not affect anti-antibody (IgM, IgG, IgG1 and IgG2a) or IL-10 production, but anti-PD-1 treatment reduced both IL-4 and TGF- production. Together, our results highlight the therapeutic potential of an 3,3′-Diindolylmethane anti-PD-1-based treatment in promoting the reinvigoration of T cells for the control of parasite burden. Subject terms: Immunotherapy, Parasite immune evasion, Infection Introduction Leishmaniasis is a disease with global ABCG2 public health concerns, particularly in poor communities. Conventional treatments arose in the 1940s; however, many problems are associated with these medications, such as high toxicity, adverse side effects, and the increased incidence of drug-resistant parasites. At present, there are no vaccines available for human use, which makes the search for new molecular targets highly necessary1. infection can cause a diverse spectrum of the disease, including cutaneous (the most common), mucosal, and visceral leishmaniasis, as well as diffuse cutaneous leishmaniasis that is refractory to the conventional treatment2. The programmed death-ligand 1 (PD-L1), a cell surface glycoprotein belonging to the B7 family is expressed on antigen-presenting cells such as neutrophils, macrophages, and dendritic cells. PD-L1 binds to the PD-1 receptor, which belongs to the CD28 family and is expressed on T cells, B cells, and myeloid cells3C5. The PD-1/PD-L1 interaction leads to the suppression of T cells by affecting the gradual loss of cell activities including cytokine secretion (IFN-, IL-2, TNF-), decreasing the proliferative capacity, and finally, inducing T cell apoptosis6,7. The PD-L1 receptor is widely discussed in oncological studies, as it is selectively expressed in many tumors4,8,9 and in cells within the tumor microenvironment in response to inflammatory stimuli10. PD-L1 is positively regulated in solid tumors, where it can inhibit cytokine production and the cytolytic activity of PD-1-expressing CD4+ and CD8+ T cells4,11,12. PD-1/PD-L1-based monoclonal antibody (MoAb) therapy is currently in phase 3,3′-Diindolylmethane III clinical trials with promising results for treatment against bladder carcinoma13 and lung cancer14. Programmed death-ligand 2 (PD-L2) is also a cell surface glycoprotein in the B7 family and plays a role similar to PD-L1, because it inhibits T cell function by binding PD-1 to the controversy in different models. T cell suppression is also reversed when the receptor is blocked by a specific antibody, for example, in inducing oral tolerance15C17. It has been shown that PD-1/PD-L1-mediated cellular exhaustion also occurs during the progression of chronic infectious diseases caused by viruses or protozoan parasites, such as AIDS, toxoplasmosis, and cutaneous leishmaniasis15,18C20. Liang and colleagues have reported that infection15. Recently it was demonstrated, a patient with diffuse cutaneous leishmaniasis, the expression of PD-1+ on CD4+ T cells and CD8+ T cell21. Thus, we hypothesize that the use of anti-PD-1 and anti-PD-L1 MoAbs would have the potential to reverse the T cell suppression phenotype observed in BALB/c mice. Therefore, here we investigate the expression of PD-1 and PD-L1 upon infection in BALB/c mice, and evaluate the use of MoAbs against PD-1 and PD-L1 as therapies for the severe form of leishmaniasis caused by (MHOM/BR/75/Josefa) 3,3′-Diindolylmethane were obtained from infected BALB/c mouse lesions and were used until the 5th culture passage as promastigotes at 26?C in M-199 medium (Cultilab) supplemented with 20% heat-inactivated fetal bovine serum (FBS) (Cultilab). infection and treatment BALB/c mice were infected subcutaneously in the right hind footpad with 2??106 stationary-phase promastigotes of in 20?l PBS. The following antibodies were administered intraperitoneally at 100?g in 100?l PBS; anti-PD-L1 (BMS-936559, Bristol-Myers Squibb), anti-PD-L2 (B7-DC, clone TY25, catalog # BE0112, Bioxcell), and anti-PD-1 (CD279, clone RMP1C14, catalog # BE0146, Bioxcell). 3,3′-Diindolylmethane The first injection was given at 7 days post-infection. Two 3,3′-Diindolylmethane treatment protocols were assessed: (i) inoculation once a week.