NK Cell Reconstitution After Autologous Hematopoietic Stem Cell Transplantation: Association Between NK Cell Maturation Stage and Outcome in Multiple Myeloma.

Autologous hematopoietic stem cell transplantation (autoHSCT) is a standard of care for transplant-eligible patients with multiple myeloma (MM). Among factors that influence outcome after autoHSCT, it has been suggested that the number of natural killer (NK) cells plays an important role. However, the impact that different NK cell subsets and their phenotype could have in disease progression after autoHSCT are less clear. For this reason, we have phenotypically and functionally characterized NK cells during immune system reconstitution after autoHSCT in 54 MM patients. Shortly after leukocyte recovery, an extensive redistribution of NK cell subsets occurs in these patients. In addition, NK cells undergo a profound phenotypic change characterized, among others, by their increased proliferative capacity and immature phenotype. Importantly, MM patients who showed lower frequencies of the mature highly differentiated NKG2A-CD57+ NK cell subset at +30 and +100 days after autoHSCT experienced superior progression-free survival and had a longer time to the next treatment than those with higher frequencies. Our results provide significant insights into NK cell reconstitution after autoHSCT and suggest that the degree of NK cell maturation after autoHSCT affects the clinical outcome of MM patients treated with this therapeutic strategy.

Emerging Role of Podocalyxin in the Progression of Mature B-Cell Non-Hodgkin Lymphoma.

Mature B-cell non-Hodgkin lymphoma (B-NHL) constitutes a group of heterogeneous malignant lymphoproliferative diseases ranging from indolent to highly aggressive forms. Although the survival after chemo-immunotherapy treatment of mature B-NHL has increased over the last years, many patients relapse or remain refractory due to drug resistance, presenting an unfavorable prognosis. Hence, there is an urgent need to identify new prognostic markers and therapeutic targets. Podocalyxin (PODXL), a sialomucin overexpressed in a variety of tumor cell types and associated with their aggressiveness, has been implicated in multiple aspects of cancer progression, although its participation in hematological malignancies remains unexplored. New evidence points to a role for PODXL in mature B-NHL cell proliferation, survival, migration, drug resistance, and metabolic reprogramming, as well as enhanced levels of PODXL in mature B-NHL. Here, we review the current knowledge on the contribution of PODXL to tumorigenesis, highlighting and discussing its role in mature B-NHL progression.

Podocalyxin promotes proliferation and survival in mature B-cell non-Hodgkin lymphoma cells.

Podocalyxin (PCLP1) is a CD34-related sialomucin expressed by some normal cells and a variety of malignant tumors, including leukemia, and associated with the most aggressive cancers and poor clinical outcome. PCLP1 increases breast tumor growth, migration and invasion; however, its role in hematologic malignancies still remains undetermined. The purpose of this study was to investigate the expression and function of PCLP1 in mature B-cell lymphoma cells. We found that overexpression of PCLP1 significantly increases proliferation, cell-to-cell interaction, clonogenicity, and migration of B-cell lymphoma cells. Furthermore, PCLP1 overexpression results in higher resistance to death induced by dexamethasone, reactive oxygen species and type II anti-CD20 monoclonal antibody obinutuzumab. Strikingly, enforced expression of PCLP1 enhances lipid droplet formation as well as pentose phosphate pathway and glutamine dependence, indicative of metabolic reprogramming necessary to support the abnormal proliferation rate of tumor cells. Flow cytometry analysis revealed augmented levels of PCLP1 in malignant cells from some patients with mature B-cell lymphoma compared to their normal B-cell counterparts. In summary, our results demonstrate that PCLP1 contributes to proliferation and survival of mature B-cell lymphoma cells, suggesting that PCLP1 may promote lymphomagenesis and represents a therapeutic target for the treatment of B-cell lymphomas.

Autoimmune lymphoproliferative syndrome due to somatic FAS mutation (ALPS-sFAS) combined with a germline caspase-10 (CASP10) variation.

Autoimmune lymphoproliferative syndrome (ALPS) is a primary immunodeficiency caused by impaired Fas/FasL-mediated apoptosis of lymphocytes and is characterized by chronic nonmalignant or benign lymphoproliferation, autoimmune manifestations and expansion of double negative (DN) T-cells (TCRαß+CD4-CD8-). Most cases of ALPS are associated with germline (ALPS-FAS) or somatic (ALPS-sFAS) heterozygous FAS mutations or a combination of both. Here we report three unrelated patients with ALPS-sFAS. Only one of them showed impaired Fas function in PHA-activated T-cells. In this patient, the genetic analysis of the caspase-10 gene (CASP10) identified a heterozygous germline change in exon 9 (c.1337A>G) causing Y446C substitution in the caspase-10 protein. In addition, this patient had a dysregulated T- and B-cell phenotype; circulating lymphocytes showed expansion of T effector memory CD45RA+ (TEMRA) CD4 T-cells, effector memory CD8 T-cells, CD21(low) B-cells and reduced memory switched B-cells. Additionally, this patient showed altered expression in T-cells of several molecules that change during differentiation from naïve to effector cells (CD27, CD95, CD57 and perforin). Molecular alterations in genes of the Fas pathway are necessary for the development of ALPS and this syndrome could be influenced by the concurrent effect of other mutations hitting different genes involved in Fas or related pathways.

Podocalyxin-like protein 1 functions as an immunomodulatory molecule in breast cancer cells.

Podocalyxin-like protein 1 (PCLP1), a CD34-related sialomucin involved in the regulation of cellular morphology and adhesion, is expressed by a number of normal cells and various tumor cells. In breast malignancies PCLP1 overexpression has been associated with the most aggressive, metastatic cancers and poor prognosis. These observations suggest that PCLP1 expression could provide a mechanism to evade the immune response, thereby promoting metastatic progression of cancer. In the present work, we aimed to determine the effect of PCLP1 overexpressed in MCF7 breast cancer cells on natural killer (NK) cell cytotoxicity, dendritic cell maturation, and agonist-induced T cell proliferation. The results showed that PCLP1 expressed in MCF7 breast cancer cells confers resistance to NK cell-mediated cytolysis and impairs T cell proliferation. Furthermore, PCLP1 decreased the levels of NK cell activating receptors NKG2D, NKp30, NKp44, NKp46, DNAM-1, and CD16 on cell surface in a contact-dependent manner. Moreover, NK cells acquired PCLP1 from MCF7 cells by a process known as trogocytosis. These data reveal a new function of PCLP1 expressed on tumor cells as an immunomodulatory molecule, which may represent a mechanism to evade the immune response.

Natural killer cells for cancer immunotherapy: pluripotent stem cells-derived NK cells as an immunotherapeutic perspective.

Natural killer (NK) cells play an essential role in the fight against tumor development. Over the last years, the progress made in the NK-cell biology field and in deciphering how NK-cell function is regulated, is driving efforts to utilize NK-cell-based immunotherapy as a promising approach for the treatment of malignant diseases. Therapies involving NK cells may be accomplished by activating and expanding endogenous NK cells by means of cytokine treatment or by transferring exogenous cells by adoptive cell therapy and/or by hematopoietic stem cell transplantation. NK cells that are suitable for adoptive cell therapy can be derived from different sources, including ex vivo expansion of autologous NK cells, unstimulated or expanded allogeneic NK cells from peripheral blood, derived from CD34+ hematopoietic progenitors from peripheral blood and umbilical cord blood, and NK-cell lines. Besides, genetically modified NK cells expressing chimeric antigen receptors or cytokines genes may also have a relevant future as therapeutic tools. Recently, it has been described the derivation of large numbers of functional and mature NK cells from pluripotent stem cells, both embryonic stem cells and induced pluripotent stem cells, which adds another tool to the expanding NK-cell-based cancer immunotherapy arsenal.

Involvement of platelet-tumor cell interaction in immune evasion. Potential role of podocalyxin-like protein 1.

Besides their essential role in hemostasis and thrombosis, platelets are involved in the onset of cancer metastasis by interacting with tumor cells. Platelets release secretory factors that promote tumor growth, angiogenesis, and metastasis. Furthermore, the formation of platelet-tumor cell aggregates in the bloodstream provides cancer cells with an immune escape mechanism by protecting circulating malignant cells from immune-mediated lysis by natural killer (NK) cells. Platelet-tumor cell interaction is accomplished by specific adhesion molecules, including integrins, selectins, and their ligands. Podocalyxin-like protein 1 (PCLP1) is a selectin-ligand protein in which overexpression has been associated with several aggressive cancers. PCLP1 expression enhances cell adherence to platelets in an integrin-dependent process and through the interaction with P-selectin expressed on activated platelets. However, the involvement of PCLP1-induced tumor-platelet interaction in tumor immune evasion still remains unexplored. The identification of selectin ligands involved in the interaction of platelets with tumor cells may provide help for the development of effective therapies to restrain cancer cell dissemination. This article summarizes the current knowledge on molecules that participate in platelet-tumor cell interaction as well as discusses the potential role of PCLP1 as a molecule implicated in tumor immune evasion.

Differential expression of viral PAMP receptors mRNA in peripheral blood of patients with chronic hepatitis C infection.

BACKGROUND: Pathogen-associated molecular patterns (PAMP) receptors play a key role in the early host response to viruses. In this work, we determined mRNA levels of two members of the Toll-like Receptors family, (TLR3 and TLR7) and the helicase RIG-I, all of three recognizing viral RNA products, in peripheral blood of healthy donors and hepatitis C virus (HCV) patients, to observe if their transcripts are altered in this disease. METHODS: IFN-alpha, TLR3, TLR7 and RIG-I levels in peripheral blood from healthy controls (n = 18) and chronic HCV patients (n = 18) were quantified by real-time polymerase chain reaction. RESULTS: Our results show that IFN-alpha, TLR3, TLR7 and RIG-I mRNA levels are significantly down-regulated in patients with chronic HCV infection when compared with healthy controls. We also found that the measured levels of TLR3 and TLR7, but not RIG-I, correlated significantly with those of IFN-alpha CONCLUSION: Monitoring the expression of RNA-sensing receptors like TLR3, TLR7 and RIG-I during the different clinical stages of infection could bring a new source of data about the prognosis of disease.