ABSTRACT
Sepsis is characterized by an early pro-inflammatory phase followed by compensatory anti-inflammatory mechanisms that lead to a late generalized immunosuppression, period where most deaths occur. Immunotherapy approaches to recover the immunocompetence in sepsis are similar to those used in cancer. Meta-tyrosine (m-Tyr) is a product of oxidative stress present in circulation during the sepsis and cancer-associated pro-inflammatory stages. In this work, considering its potential participation in pro-inflammatory processes, we evaluate the effect of m-Tyr during LPS induced immunosuppression phase in a murine model. In addition, we examine the effect of m-Tyr in a vaccination strategy using a weakly immunogenic tumor model. Our results showed that m-Tyr could prevent the establishment of immunosuppression and rescue the host from an installed immunosuppression induced by LPS. These effects were parallel to the ability of m-Tyr to improve the pro-inflammatory effects induced by LPS and inhibit the anti-inflammatory action of dexamethasone. Also, m-Tyr treatment prevents both the reduction of splenic lymphocytes and the increase of the expression of programmed death ligand-1 in splenic myeloid cells associated with immunosuppression. Besides, treatment with m-Tyr increased the protective effect of an anti-tumor vaccine, suggesting that m-Tyr could improve the immune response. In summary, we suggest that m-Tyr can modulate critical immunological indicators through the inflammatory context, which could improve the management of diseases, such as sepsis and cancer, in which immunosuppression is a significant clinical problem.
Subject(s)
Cancer Vaccines/immunology , Immunologic Factors/therapeutic use , Mammary Neoplasms, Animal/therapy , Myeloid-Derived Suppressor Cells/physiology , Sepsis/therapy , Tyrosine/therapeutic use , Animals , B7-H1 Antigen/antagonists & inhibitors , Cell Line, Tumor , Disease Models, Animal , Female , Gene Expression Regulation, Neoplastic , Humans , Lipopolysaccharides/immunology , Mammary Neoplasms, Animal/immunology , Mice , Mice, Inbred BALB C , Myeloid-Derived Suppressor Cells/drug effects , Neoplasm Metastasis , Sepsis/immunologyABSTRACT
MC-C fibrosarcoma and B16F0 melanoma tumors were implanted intradermally in the dorsal region of the foot of mice. Tumor progression was compared to standard implantation in the flank. Although foot tumors only reached 13% (MC-C) and 25% (B16F0) of the mean volume of flank tumors, a more malignant phenotype in terms of histology and survival rate was observed in this type of tumors. Moreover, lung metastases were only detected in hosts bearing foot tumors, in contrast to MC-C and B16F0 populations with tumors growing in the flank. In addition, cellular influx and local immune reaction were higher in the dorsal region of the foot. According to our results, the dermis of the flank allows excessive tumor growth due to its low reactivity. Thus, differences in innate and adaptive immune effectors between the evaluated tumor microenvironments would account for the differences in tumor malignancy. Due to its striking differences with the standard flank inoculation, the tumor implantation model herein introduced could be a valuable tool to study the metastatic potential of different cell lines and the microenvironment components affecting tumor growth.
