Use of CD137 ligand expression in the detection of small B-cell lymphomas involving the bone marrow

Role of the Bone Marrow Niche in Supporting the Pathogenesis of Lymphoid Malignancies

While the bone marrow (BM) microenvironment is the primary location for nurturing the multipotent hematopoietic stem cells and developing the blood cells of either myeloid or lymphoid origin under normal physiological conditions, it could provide a supportive milieu for the proliferation of blood cancer cells. In fact, the multiple and complex direct cell-to-cell or indirect soluble factors-mediated interactions taking place among the BM cells of different origins are shown to play a significant role in tumorigenesis of hematological cancers. In the current review, we focus on lymphoid malignancies and highlight the novel insights surrounding the role of both cellular as well as non-cellular BM compartments in modulating hematopoiesis and promoting growth and proliferation of cancer cells across a variety of aggressive and indolent lymphoid malignancies, including diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, and Waldenstrom Macroglobulinemia. We also discuss the mechanisms of potential intervention and discuss their therapeutic impact in clinical settings.

B cell subset alteration and the expression of tissue homing molecules in dengue infected patients

Background

B cells play an essential role during dengue viral infection. While a major expansion of antibody secreting cells (ASCs) was observed, the importance of these increased frequencies of ASCs remains unclear. The alteration of B cell subsets may result from the expression of tissue specific homing molecules leading to their mobilization and distribution to different target organs during acute dengue viral infection.

Methods

In this study, whole blood samples were obtained from thirty pediatric dengue-infected patients and ten healthy children and then stained with fluorochrome-conjugated monoclonal antibodies against CD3, CD14, CD19, CD20, CD21, CD27, CD38, CD45, CD138 and homing molecules of interest before analyzed by polychromatic flow cytometry. B cell subsets were characterized throughout acute infection period.

Results

Data shows that there were no detectable differences in frequencies of resting, activated and tissue memory cells, whereas the frequency of ASCs was significantly increased and associated with the lower frequency of naïve cells. These results were found from patients with both dengue fever and dengue hemorrhagic fever, suggesting that such change or alteration of B cells was not associated with disease severity. Moreover, several homing molecules (e.g., CXCR3 and CCR2) were found in ASCs, indicating that ASCs may distribute to inflamed tissues and various organs.

Conclusions

Findings from this study provide insight into B cell subset distribution. Furthermore, organ mobilization according to homing molecule expression on different B cell subsets during the course of dengue viral infection also suggests they are distributed to inflamed tissues and various organs.

TNFSF9 exerts an inhibitory effect on hepatocellular carcinoma

OBJECTIVE

Tumor necrosis factor superfamily member 9 (TNFSF9), also known as 4-1BBL and CD137L, has been implicated in cancer immunotherapy due to its function as a T-cell co-stimulator. We aimed to investigate the role of TNFSF9 in the cancer pathogenesis in hepatocellular carcinoma (HCC).

METHODS

TNFSF9 expression was examined by immunohistochemistry in 106 pairs of HCC and adjacent non-tumorous tissues, and by quantitative polymerase chain reaction and Western blot in HCC cell lines. The impact of TNFSF9 on the proliferation, migration and invasion of HCC cells was determined using the 3-(4,5-diethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) and transwell assays in vitro. We also assessed the influence of TNFSF9 on the growth and metastasis of HCC tumors in an orthotopic mouse model of human HCC.

RESULTS

TNFSF9 expression was downregulated in approximately 70% of HCC tissues. A decreased expression of TNFSF9 was also consistently observed in all the four HCC cell lines. Either the overexpression of TNFSF9 or treatment with recombinant TNFSF9 protein could significantly inhibit the proliferation, migration and invasion of Huh7 and SMMC-7721 HCC cells in vitro. The inhibitory effect of TNFSF9 on HCC was further confirmed in vivo. Mice orthotopically transplanted with TNFSF9-overexpressing Huh7 cells developed significantly smaller tumors with less intrahepatic metastasis and distant metastasis compared with the control group.

CONCLUSIONS

TNFSF9 may be a tumor suppressor in HCC. Based on its immune stimulatory aspect and the tumor inhibition property, TNFSF9 may be a promising therapeutic target for HCC.

Programming the immune checkpoint to treat hematologic malignancies

INTRODUCTION

Hematologic malignancies manipulate the immune suppressive pathways involving CTLA-4, PD-1, and others to promote immune tolerance of cancer. New monoclonal antibodies targeting immune checkpoints are showing meaningful responses in the treatment of relapsed and refractory Hodgkin lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, and chronic lymphocytic leukemia. The basis for success of anti-PD-1 therapy appears to be expression of PD-L1 on tumor cells and cells of the tumor microenvironment (TME). While adverse events associated with immune checkpoint inhibitors are capable of generating auto-immune phenomena, in general these therapies are well tolerated.

AREAS COVERED

In this review, the authors discuss the development of immune checkpoint inhibitors and activators which hold promise as useful therapies in malignancies of hematologic origin, since many exploit endogenous pathways to induce tolerance. By programming the immune response to attack hematologic malignancies, unique regimens can be developed to optimally treat patients with curative potential.

EXPERT OPINION

The utilization of immune checkpoint targeting agents to boost the innate and acquired immune systems to eradicate human malignancies represents a unique opportunity to develop novel therapies with increased clinical efficacy. Side effects of these therapies come with the price of auto-immune phenomena that require appropriate management.

HITS-CLIP analysis uncovers a link between the Kaposi's sarcoma-associated herpesvirus ORF57 protein and host pre-mRNA metabolism

The Kaposi's sarcoma associated herpesvirus (KSHV) is an oncogenic virus that causes Kaposi's sarcoma, primary effusion lymphoma (PEL), and some forms of multicentric Castleman's disease. The KSHV ORF57 protein is a conserved posttranscriptional regulator of gene expression that is essential for virus replication. ORF57 is multifunctional, but most of its activities are directly linked to its ability to bind RNA. We globally identified virus and host RNAs bound by ORF57 during lytic reactivation in PEL cells using high-throughput sequencing of RNA isolated by cross-linking immunoprecipitation (HITS-CLIP). As expected, ORF57-bound RNA fragments mapped throughout the KSHV genome, including the known ORF57 ligand PAN RNA. In agreement with previously published ChIP results, we observed that ORF57 bound RNAs near the oriLyt regions of the genome. Examination of the host RNA fragments revealed that a subset of the ORF57-bound RNAs was derived from transcript 5' ends. The position of these 5'-bound fragments correlated closely with the 5'-most exon-intron junction of the pre-mRNA. We selected four candidates (BTG1, EGR1, ZFP36, and TNFSF9) and analyzed their pre-mRNA and mRNA levels during lytic phase. Analysis of both steady-state and newly made RNAs revealed that these candidate ORF57-bound pre-mRNAs persisted for longer periods of time throughout infection than control RNAs, consistent with a role for ORF57 in pre-mRNA metabolism. In addition, exogenous expression of ORF57 was sufficient to increase the pre-mRNA levels and, in one case, the mRNA levels of the putative ORF57 targets. These results demonstrate that ORF57 interacts with specific host pre-mRNAs during lytic reactivation and alters their processing, likely by stabilizing pre-mRNAs. These data suggest that ORF57 is involved in modulating host gene expression in addition to KSHV gene expression during lytic reactivation.