Chemotherapy Induces Cancer-Fighting B Cells

IgD ligation allows peritoneal cavity B cell proliferation

Atypical cytokine production and immune cell subset ratios, particularly those that include high proportions of macrophages, characterize tumor microenvironments (TMEs). TMEs can be modeled by culturing peritoneal cavity (PerC) cells which have a high macrophage to lymphocyte ratio. With TCR or BCR ligation, PerC lymphocyte proliferation is tempered by macrophages. However, PHA (T cells) and anti-CD40 (B cells) are activators that induce proliferation. Herein, we report that ligating IgD, in contrast to IgM, triggers PerC B cell proliferation. IL-4 addition enhanced the IgD response for BALB/c PerC B cells but suppressed that of C57BL/6 mice. Intriguingly, concurrent ligation of IgD and CD3_ε rescued a PerC T cell proliferative response. These results serve to expand the list of targets for promoting cellular and humoral immunity in conditions that model macrophage-rich TMEs.

Antigen presentation and interferon signatures in B cells driven by localized ablative cancer immunotherapy correlate with extended survival

Rationale: B cells have emerged as key regulators in protective cancer immunity. However, the activation pathways induced in B cells during effective immunotherapy are not well understood. Methods: We used a novel localized ablative immunotherapy (LAIT), combining photothermal therapy (PTT) with intra-tumor delivery of the immunostimulant N-dihydrogalactochitosan (GC), to treat mice bearing mouse mammary tumor virus-polyoma middle tumor-antigen (MMTV-PyMT). We used single-cell RNA sequencing to compare the transcriptional changes induced by PTT, GC and PTT+GC in B cells within the tumor microenvironment (TME). Results: LAIT significantly increased survival in the tumor-bearing mice, compared to the treatment by PTT and GC alone. We found that PTT, GC and PTT+GC increased the proportion of tumor-infiltrating B cells and induced gene expression signatures associated with B cell activation. Both GC and PTT+GC elevated gene expression associated with antigen presentation, whereas GC elevated transcripts that regulate B cell activation and GTPase function and PTT+GC induced interferon response genes. Trajectory analysis, where B cells were organized according to pseudotime progression, revealed that both GC and PTT+GC induced the differentiation of B cells from a resting state towards an effector phenotype. The analyses confirmed upregulated interferon signatures in the differentiated tumor-infiltrating B cells following treatment by PTT+GC but not by GC. We also observed that breast cancer patients had significantly longer survival time if they had elevated expression of genes in B cells that were induced by PTT+GC therapy in the mouse tumors. Conclusion: Our findings show that the combination of local ablation and local application of immunostimulant initiates the activation of interferon signatures and antigen-presentation in B cells which is associated with positive clinical outcomes for breast cancer. These findings broaden our understanding of LAIT's regulatory roles in remodeling TME and shed light on the potentials of B cell activation in clinical applications.

Chemotherapy: a double-edged sword in cancer treatment

Chemotherapy is a well-known and effective treatment for different cancers; unfortunately, it has not been as efficient in the eradication of all cancer cells as been expected. The mechanism of this failure was not fully clarified, yet. Meanwhile, alterations in the physiologic conditions of the tumor microenvironment (TME) were suggested as one of the underlying possibilities. Chemotherapy drugs can activate multiple signaling pathways and augment the secretion of inflammatory mediators. Inflammation may show two opposite roles in the TME. On the one hand, inflammation, as an innate immune response, tries to suppress tumor growth but on the other hand, it might be not powerful enough to eradicate the cancer cells and even it can provide appropriate conditions for cancer promotion and relapse as well. Therefore, the administration of mild anti-inflammatory drugs during chemotherapy might result in more successful clinical results. Here, we will review and discuss this hypothesis. Most chemotherapy agents are triggers of inflammation in the tumor microenvironment through inducing the production of senescence-associated secretory phenotype (SASP) molecules. Some chemotherapy agents can induce systematic inflammation by provoking TLR4 signaling or triggering IL-1B secretion through the inflammasome pathway. NF-kB and MAPK are key signaling pathways of inflammation and could be activated by several chemotherapy drugs. Furthermore, inflammation can play a key role in cancer development, metastasis and exacerbation.

Brain-derived neurotrophic factor in hematological malignancies: From detrimental to potentially beneficial

Emerging studies have highlighted brain-derived neurotrophic factor (BDNF), a neuronal growth factor abundant in the peripheral blood, and its tyrosine kinase receptor TRKB, as onco-genes and proteins that support the survival of malignant hematological cells. In contrast, other researchers reported on a favorable association between BDNF blood levels and prognosis, chemotherapy response and neurological side effects in patients with hematological malignancies. Here, we review the accumulated data regarding the expression of BDNF and its receptors in normal hematopoietic and lymphatic cells and tissue. In addition, in-vitro experiments, animal models and human sample studies that investigated the role of BDNF and its receptors in hematological malignancies are discussed. Finally, directions for future research aimed at revealing the mechanisms underlying the protective effect of BDNF in patients with these diseases are suggested.

IL-35 Regulates the Function of Immune Cells in Tumor Microenvironment

Interleukin-35 (IL-35) is a heterodimeric cytokine composed of Epstein-Barr virus-induced gene 3 (EBI3) and IL-12p35 that has recently been shown to play diverse and important roles in the tumor microenvironment (TME). Owing to its immunosuppressive activity and ability to promote tumor growth and progression, IL-35 is widely recognized as a key mediator of TME status. Immune cells are key mediators of diverse tumor-related phenotypes, and immunosuppressive cytokines such as IL-35 can promote tumor growth and metastasis in TME. These influences should be considered together. Since tumor immunotherapy based on immune checkpoint blockade remains ineffective in many patients due to tumoral resistance, a new target or efficacy enhancing factor is urgently needed. Suppressing IL-35 production and activity has been demonstrated as an effective factor that inhibits tumor cells viability, and further investigation of this cytokine is warranted. However, the mechanistic basis for IL-35-mediated regulation of immune cells in the TME remains to be fully clarified. In the present review, we explore the roles of IL-35 in regulating immune cells within the TME. In addition, we highlight IL-35 as a specific immunological target and discuss its possible relevance in the context of immunotherapy. Lastly, we sought to summarize potential future research directions that may guide the advancement of current understanding regarding the role of this important cytokine as a regulator of oncogenesis.

Tumor-infiltrating lymphocytes in the immunotherapy era

The clinical success of cancer immune checkpoint blockade (ICB) has refocused attention on tumor-infiltrating lymphocytes (TILs) across cancer types. The outcome of immune checkpoint inhibitor therapy in cancer patients has been linked to the quality and magnitude of T cell, NK cell, and more recently, B cell responses within the tumor microenvironment. State-of-the-art single-cell analysis of TIL gene expression profiles and clonality has revealed a remarkable degree of cellular heterogeneity and distinct patterns of immune activation and exhaustion. Many of these states are conserved across tumor types, in line with the broad responses observed clinically. Despite this homology, not all cancer types with similar TIL landscapes respond similarly to immunotherapy, highlighting the complexity of the underlying tumor-immune interactions. This observation is further confounded by the strong prognostic benefit of TILs observed for tumor types that have so far respond poorly to immunotherapy. Thus, while a holistic view of lymphocyte infiltration and dysfunction on a single-cell level is emerging, the search for response and prognostic biomarkers is just beginning. Within this review, we discuss recent advances in the understanding of TIL biology, their prognostic benefit, and their predictive value for therapy.

A novel cancer immunotherapy using tumor-infiltrating B cells in the APCmin/+ mouse model

Accumulating evidence has suggested a correlation of tumor infiltrating B cells (TiBcs) and a good prognosis of cancer diseases. In some cases, TiBcs appear to have experienced antigen stimulation since they have undergone class-switching and somatic hypermutation and formed tertiary lymphoid structures around tumors together with T cells. Assuming TiBcs include those that recognize some tumor antigens, we sought to investigate their possible usefulness for cell-mediated immunotherapies. To expand usually small number of TiBcs in vitro, we modified our B cell culture system: we transduced B cells with ERT2-Bach2 so that they grow unlimitedly provided with tamoxifen, IL-21 and our original feeder cells. Such cells differentiate into plasma cells and produce antibodies upon withdrawal of tamoxifen, and further by addition of a Bach2-inhibitor in vitro. As a preliminary experiment, thus expanded splenic B cells expressing a transgenic antigen receptor/antibody against hen egg lysozyme were intravenously injected into mice pre-implanted with B16 melanoma cells expressing membrane-bound HEL in the skin, which resulted in suppression of the growth of B16 tumors and prolonged survival of the recipient mice. To test the usefulness of TiBcs for the immunotherapy, we next used APCmin/+ mice as a model that spontaneously develop intestinal tumors. We cultured TiBcs separated from the tumors of APCmin/+ mice as above and confirmed that the antibodies they produce recognize the APCmin/+ tumor. Repeated injection of such TiBcs into adult APCmin/+ mice resulted in suppression of intestinal tumor growth and elongation of the survival of the recipient mice. Serum antibody from the TiBc-recipient mice selectively bound to an antigen expressed in the tumor of APCmin/+ mice. These data suggest a possibility of the novel individualized cancer immunotherapy, in which TiBcs from surgically excised tumor tissues are expanded and infused into the donor patients.

Immune escape: A critical hallmark in solid tumors

Incapacitated immune system is a characteristic hallmark of solid tumors. Immune system within a tumor undergoes an imbalance in cellular dispersion and functionality. Effector cells are precluded from the invasive margin of tumor; instead, immune suppressor cells are present at high fractions. Conditions in the tumor microenvironment (TME) like altered metabolism, chronic hypoxia and chronic inflammation are the known predisposing factors, implicated in the immune malfunctioning. Deficiency of innate immune sensing mediated by checkpoint receptors including programmed death-1 receptor (PD-1), CTL-associated antigen-4 (CTLA-4) hijacked by tumor cells takes a major part of the blame, requiring a need for appropriate strategies in order to bring back the balance in the immune system. Immune checkpoint inhibitor (ICI) therapy has been in the eye of the current research rendering promising results. The story is not, however, that easy in which it is not so effective for Cold tumors, it may cause severe adverse effects, and that patients may acquire resistance to such therapy; this requires for updating the current knowledge about the immune ecosystem, using tumor type dependent dose calculation and exploiting proper adjuvants in order for evolving desired responses.