Macrophage Gal/GalNAc lectin 2 (MGL2)+ peritoneal antigen presenting cells during Fasciola hepatica infection are essential for regulatory T cell induction

Fasciola hepatica, one of the agents that causes fasciolosis, modulates the host immune system to allow parasite survival in the host. F. hepatica expresses carbohydrate-containing glycoconjugates that are decoded by C-type lectin receptors, such as Dectin-1, mannose receptor, DC-SIGN and MGL, that are mainly present on myeloid antigen presenting cells (APCs) and can mediate immunoregulatory properties on T cells. In particular, Macrophage Gal/GalNAc lectin 2 (MGL2) expands modified Th2 immune responses, while suppressing Th1 polarization, upon recognition of GalNAc-glycosylated parasite components. In this study, by using MGL2-DTR transgenic mice that encode human diphtheria toxin receptor in MGL2+ cells, we demonstrate the role of peritoneal APCs during F. hepatica infection in favoring parasite survival. This process might be mediated by the induction of splenic Tregs in vivo, since the depletion of MGL2+ cells conferred mice with partial resistance to the infection and abrogated the increase of CD4+/CD25+ FoxP3+ Tregs induced by the parasite. Therefore, MGL2+ cells are critical determinants of F. hepatica infection and could constitute immune checkpoints to control parasite infection.Agencia Nacional de Investigación e InnovaciónPrograma de Desarrollo de las Ciencias Básica

Heme-Oxygenase-1 Attenuates Oxidative Functions of Antigen Presenting Cells and Promotes Regulatory T Cell Differentiation during Fasciola hepatica Infection

Fasciola hepatica is a fluke that infects livestock and humans causing fasciolosis, a zoonotic disease of increasing importance due to its worldwide distribution and high economic losses. The parasite regulates the host immune system by inducing a strong Th2 and regulatory T (Treg) cell immune response through mechanisms that might involve the expression or activity of heme-oxygenase-1 (HO-1), the rate-limiting enzyme in the catabolism of free heme that also has immunoregulatory and antioxidant properties. In this paper, we show that F. hepatica-infected mice upregulate HO-1 on peritoneal antigen-presenting cells (APC), which produce decreased levels of both reactive oxygen and nitrogen species (ROS/RNS). The presence of these cells was associated with increased levels of regulatory T cells (Tregs). Blocking the IL-10 receptor (IL-10R) during parasite infection demonstrated that the presence of splenic Tregs and peritoneal APC expressing HO-1 were both dependent on IL-10 activity. Furthermore, IL-10R neutralization as well as pharmacological treatment with the HO-1 inhibitor SnPP protected mice from parasite infection and allowed peritoneal APC to produce significantly higher ROS/RNS levels than those detected in cells from infected control mice. Finally, parasite infection carried out in gp91phox knockout mice with inactive NADPH oxidase was associated with decreased levels of peritoneal HO-1+ cells and splenic Tregs, and partially protected mice from the hepatic damage induced by the parasite, revealing the complexity of the molecular mechanisms involving ROS production that participate in the complex pathology induced by this helminth. Altogether, these results contribute to the elucidation of the immunoregulatory and antioxidant role of HO-1 induced by F. hepatica in the host, providing alternative checkpoints that might control fasciolosis.Agencia Nacional de Investigación e InnovaciónPrograma de Desarrollo de las Ciencias Básica

The tumor-associated Tn antigen fosters lung metastasis and recruitment of regulatory T cells in triple negative breast cancer

Laboratorio de Inmunomodulación y Desarrollo de Vacunas, Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay -- Contacto: [email protected] is a leading cause of death worldwide, accounting for nearly 10 million deaths. Among breast cancers (BC) subtypes, triple-negative (TN) BC is characterized by metastatic progression and poor patient prognosis. Although TNBC is initially sensitive to chemotherapy, many TNBC patients rapidly develop resistance, at which point metastatic disease is highly lethal. Cancer cells present phenotypic changes or molecular signatures that distinguish them from healthy cells. The Tn antigen (GalNAc-O-Thr/Ser), which constitutes a powerful tool as tumor marker, was recently reported to contribute to tumor growth. However, its role in BC-derived metastasis has not yet been addressed. In this work, we generated a pre-clinical orthotopic Tn+ model of metastatic TNBC, which mimics the patient surgical treatment and is useful to study the role of Tn in metastasis and immunoregulation. We obtained two different cell clones, which differed in their Tn antigen expression: a high Tn-expressing and a non-expressing clone. Interestingly, the Tn-positive cell line generated significantly larger tumors and higher degree of lung metastases associated with a lower survival rate than the Tn-negative and parental cell line. Furthermore, we also found that both tumors and draining-lymph nodes from Tn+-tumor-bearing mice presented a higher frequency of CD4+ FoxP3+ T cells, while their splenocytes expressed higher levels of IL-10. In conclusion, this work suggests that the Tn antigen participates in breast tumor growth and spreading, favoring metastases to the lungs that are associated with an immunoregulatory state, suggesting that Tn-based immunotherapy could be a strategy of choice to treat these tumors

Lung Tumor Cells with Different Tn Antigen Expression Present Distinctive Immunomodulatory Properties

Lung cancer is the first leading cause of cancer-related deaths in the world. Aberrant glycosylation in lung tumors leads to the expression of tumor-associated carbohydrate structures, such as the Tn antigen, consisting of N-acetyl-galactosamine (GalNAc) linked to a serine or threonine residue in proteins (α-GalNAc-O-Ser/Thr). The Tn antigen can be recognized by the Macrophage Galactose/GalNAc lectin (MGL), which mediates various immune regulatory and tolerogenic functions, mainly by reprogramming the maturation of function of dendritic cells (DCs). In this work, we generated two different Tn-expressing variants from the Lewis-type lung murine cancer cell line LL/2, which showed different alterations in the O-glycosylation pathways that influenced the interaction with mouse MGL2 and the immunomodulatory properties of DCs. Thus, the identification of the biological programs triggered by Tn+ cancer cells might contribute to an improved understanding of the molecular mechanisms elicited by MGL-dependent immune regulatory circuits

The Tn antigen promotes lung tumor growth by fostering immunosuppression and angiogenesis via interaction with Macrophage Galactose-type lectin 2 (MGL2)

Tn is a tumor-associated carbohydrate antigen that constitutes both a diagnostic tool and an immunotherapeutic target. It originates from interruption of the mucin O-glycosylation pathway through defects involving, at least in part, alterations in core-1 synthase activity, which is highly dependent on Cosmc, a folding chaperone. Tn antigen is recognized by the Macrophage Galactose-type Lectin (MGL), a C-type lectin receptor present on dendritic cells and macrophages. Specific interactions between Tn and MGL shape anti-tumoral immune responses by regulating several innate and adaptive immune cell programs. In this work, we generated and characterized a variant of the lung cancer murine cell line LL/2 that expresses Tn by mutation of the Cosmc chaperone gene (Tn+ LL/2). We confirmed Tn expression by lectin glycophenotyping and specific anti-Tn antibodies, verified abrogation of T-synthase activity in these cells, and confirmed its recognition by the murine MGL2 receptor. Interestingly, Tn+ LL/2 cells were more aggressive in vivo, resulting in larger and highly vascularized tumors than those generated from wild type Tn− LL/2 cells. In addition, Tn+ tumors exhibited an increase in CD11c+ F4/80+ cells with high expression of MGL2, together with an augmented expression of IL-10 in infiltrating CD4+ and CD8+ T cells. Importantly, this immunosuppressive microenvironment was dependent on the presence of MGL2+ cells, since depletion of these cells abrogated tumor growth, vascularization and recruitment of IL-10+ T cells. Altogether, our results suggest that expression of Tn in tumor cells and its interaction with MGL2-expressing CD11c+F4/80+ cells promote immunosuppression and angiogenesis, thus favoring tumor progression.Fil: da Costa, Valeria. Universidad de la República; UruguayFil: van Vliet, Sandra J.. University of Amsterdam; Países BajosFil: Carasi, Paula. Universidad de la República; Uruguay. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Frigerio, Sofía. Universidad de la República; UruguayFil: García, Pablo A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Croci Russo, Diego Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Festari, María Florencia. Universidad de la República; UruguayFil: Costa, Monique. Universidad de la República; UruguayFil: Landeira, Mercedes. Universidad de la República; UruguayFil: Rodríguez Zraquia, Santiago A.. Universidad de la República; UruguayFil: Cagnoni, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Cutine, Anabela María. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Rabinovich, Gabriel Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Osinaga, Eduardo. Universidad de la República; UruguayFil: Mariño, Karina Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Freire Gard, Teresa Inés. Universidad de la República; Urugua