Interrupting the nitrosative stress fuels tumor-specific cytotoxic T lymphocytes in pancreatic cancer

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest tumors owing to its robust desmoplasia, low immunogenicity, and recruitment of cancer-conditioned, immunoregulatory myeloid cells. These features strongly limit the success of immunotherapy as a single agent, thereby suggesting the need for the development of a multitargeted approach. The goal is to foster T lymphocyte infiltration within the tumor landscape and neutralize cancer-triggered immune suppression, to enhance the therapeutic effectiveness of immune-based treatments, such as anticancer adoptive cell therapy (ACT).

Methods

We examined the contribution of immunosuppressive myeloid cells expressing arginase 1 and nitric oxide synthase 2 in building up a reactive nitrogen species (RNS)-dependent chemical barrier and shaping the PDAC immune landscape. We examined the impact of pharmacological RNS interference on overcoming the recruitment and immunosuppressive activity of tumor-expanded myeloid cells, which render pancreatic cancers resistant to immunotherapy.

Results

PDAC progression is marked by a stepwise infiltration of myeloid cells, which enforces a highly immunosuppressive microenvironment through the uncontrolled metabolism of L-arginine by arginase 1 and inducible nitric oxide synthase activity, resulting in the production of large amounts of reactive oxygen and nitrogen species. The extensive accumulation of myeloid suppressing cells and nitrated tyrosines (nitrotyrosine, N-Ty) establishes an RNS-dependent chemical barrier that impairs tumor infiltration by T lymphocytes and restricts the efficacy of adoptive immunotherapy. A pharmacological treatment with AT38 ([3-(aminocarbonyl)furoxan-4-yl]methyl salicylate) reprograms the tumor microenvironment from protumoral to antitumoral, which supports T lymphocyte entrance within the tumor core and aids the efficacy of ACT with telomerase-specific cytotoxic T lymphocytes.

Conclusions

Tumor microenvironment reprogramming by ablating aberrant RNS production bypasses the current limits of immunotherapy in PDAC by overcoming immune resistance.

Oral Plasmablastic Lymphoma: A Case Report of an HIV Negative Patient with an Unusual Clinical Signature

Plasmablastic Lymphoma (PBL) is an aggressive variant of diffuse large B-cell lymphoma with a low survival rate. It is associated with Human Immunodeficiency Virus (HIV) infection but also affects patients with autoimmune diseases as chronic lymphocytic leukaemia, systemic lupus erythematosus and with long-term immunosuppression for heart and kidney transplants, ulcerative colitis. It has been reported in immunocompetent and HIV negative patients, determining the diagnosis more challenging. A rare case of bleeding gingival hyperplastic PBL in the left posterior mandibular area in a 61-year-old HIV negative male patient is reported. Histological assessment showed that oral mucosa was infiltrated by a monomorphic population of large lymphoid elements with morphological characteristics similar to immunoblasts with a “starry sky” appearance. Immunohistochemical markers were positive for CD138, Kappa and Lambda light chains, and negative for CKAE1/3, Synaptophysine, Chromogranin, CD56, and CD20. The detection of the primary oral manifestation of PBL remains challenging in immunocompetent patients and this case report aims to broaden the knowledge of the possible oral clinical aspects of PBL.