Plasma Cell Polarization to the Immunoglobulin G Phenotype in Hepatocellular Carcinomas Involves Epigenetic Alterations and Promotes Hepatoma Progression in Mice.

BACKGROUND & AIMS: Little is known about the composition and generation of plasma cell subsets in patients with hepatocellular carcinoma (HCC) and how these associate with outcomes. We investigated whether, or how, plasma cells differentiate and function in patients with HCC and mice with liver tumors. METHODS: We analyzed subset composition and distribution of plasma cells in HCC samples from 342 patients who underwent curative resection at the Cancer Center of Sun Yat-sen University in China; samples of non-tumor liver tissue were used as controls. We associated plasma cell profiles with patient outcomes. Tissue-derived leukocytes were analyzed by flow cytometry and real-time polymerase chain reaction. The ability of macrophages to regulate plasma cell differentiation was determined in ex vivo cultures of cells from human HCC tissues. C57BL/6 and BALB/c mice were given injections of Hepa1-6 cells, which formed hepatomas, or H22 cells, which formed ascitic hepatomas. Gene expression patterns were analyzed in human HCC, mouse hepatoma, and non-tumor tissues by real-time polymerase chain reaction. Mice with hepatomas were given injections of GSK126 (an inhibitor of histone H3 lysine 27 methyltransferase [EZH2]) and 5-AZA-dC (an inhibitor of DNA methyltransferases); tumor tissues were analyzed by immunofluorescence and immunohistochemistry for the presence of immune cells and cytokines. RESULTS: B cells isolated from HCCs had somatic hypermutations and class-switch recombinations to the IgG phenotype that were not observed in non-tumor tissues. Increased level of plasma cells correlated with poor outcomes of patients. Activated CD4+ T cells from HCCs stimulated C-X-C motif chemokine 10 (CXCL10) production by macrophages. CXCL10 bound CXC chemokine receptor 3 on B cells and signaled via extracellular signal-regulated kinase to cause them to become IgG-producing plasma cells. IgG activated Fc receptors on macrophages and induced them to produce interleukin 6, interleukin 10, and C-C motif chemokine ligand 20 (CCL20). In mice with hepatomas, depletion of B cells prevented generation of these macrophage, increased the anti-tumor T cell response, and reduced growth of hepatomas. However, these effects were lost after injection of CXC chemokine receptor 3-positive plasma cells. Human HCC and mouse hepatoma tissues had increased expression of DNA methyltransferase 1 and EZH2 compared with non-tumor tissues. Injection of mice with GSK126 and 5-AZA-dC induced expression of CXCL10 by tumor cells and caused plasma cell polarization, suppression of the anti-tumor T cell response, and hepatoma growth. CONCLUSIONS: Human HCC tissues contain B cells with class-switch recombinations to the IgG phenotype. Activated CD4+ T cells from HCCs stimulate CXCL10 production by macrophages; CXCL10 binds CXC chemokine receptor 3 on B cells and causes them to become IgG-producing plasma cells. IgG activates Fc receptor in macrophages to produce cytokines that reduce the anti-tumor immune response. In mice with hepatomas, depletion of B cells prevented generation of these macrophages, increased the anti-tumor T cell response, and reduced growth of hepatomas. This pathway involves increased expression of DNA methyltransferase 1 and EZH2 by HCC and hepatoma cells.

Chemokine (C-X-C motif) receptor 3-positive B cells link interleukin-17 inflammation to protumorigenic macrophage polarization in human hepatocellular carcinoma.

UNLABELLED: B cells consistently represent abundant cellular components in tumors; however, direct evidence supporting a role for B cells in the immunopathogenesis of human cancers is lacking, as is specific knowledge of their trafficking mechanisms. Here, we demonstrate that chemokine (C-X-C motif) receptor 3-positive (CXCR3(+)) B cells constitute approximately 45% of B-cell infiltrate in human hepatocellular carcinoma (HCC) and that their levels are positively correlated with early recurrence of HCC. These cells selectively accumulate at the invading edge of HCC and undergo further somatic hypermutation and immunoglobulin G-secreting plasma cell differentiation. Proinflammatory interleukin-17(+) cells are important for the induction of epithelial cell-derived CXCR3 ligands CXCL9, CXCL10, and CXCL11, which subsequently promote the sequential recruitment and further maturation of CXCR3(+) B cells. More importantly, we provide evidence that CXCR3(+) B cells, but not their CXCR3(-) counterparts, may operate in immunoglobulin G-dependent pathways to induce M2b macrophage polarization in human HCC. Depletion of B cells significantly suppresses M2b polarization and the protumorigenic activity of tumor-associated macrophages and restores the production of antitumorigenic interleukin-12 by those cells in vivo. CONCLUSION: Selective recruitment of CXCR3(+) B cells bridges proinflammatory interleukin-17 response and protumorigenic macrophage polarization in the tumor milieu, and blocking CXCR3(+) B-cell migration or function may help defeat HCC.

B cells polarize pathogenic inflammatory T helper subsets through ICOSL-dependent glycolysis.

B cells constitute abundant cellular components in inflamed human tissues, but their role in pathogenesis of inflammatory T helper (TH) subsets is still unclear. Here, we demonstrate that B cells, particularly resting naïve B cells, have a previously unrecognized helper function that is involved in shaping the metabolic process and subsequent inflammatory differentiation of T-cell receptor-primed TH cells. ICOS/ICOSL axis-mediated glucose incorporation and utilization were crucial for inflammatory TH subset induction by B cells, and activation of mTOR was critical for T cell glycolysis in this process. Consistently, upon encountering ICOSL+ B cells, activated effector memory TH cells from patients with rheumatoid arthritis or systemic lupus erythematosus spontaneously differentiated into inflammatory TH subsets. Immunotherapy using rituximab that specifically depleted B cells in patients with rheumatoid arthritis efficiently abrogated the capabilities of memory TH cells to incorporate and use glucose, thereby impairing the pathogenic differentiation of inflammatory TH subsets.

Polarization of Tissue-Resident TFH-Like Cells in Human Hepatoma Bridges Innate Monocyte Inflammation and M2b Macrophage Polarization.

The existence, regulation, and functions of IL21+ immune cells are poorly defined in human cancers. Here, we identified a subset of protumorigenic IL21+ TFH-like cells in human hepatocellular carcinoma. These cells were the major source of IL21 in tumors and represented about 10% of the CD4+ T-cell population at levels comparable with the TFH cells present in lymph nodes. However, these TFH-like cells displayed a unique CXCR5-PD-1lo/-BTLA-CD69hi tissue-resident phenotype with substantial IFNγ production, which differed from the phenotype of TFH cells. Toll-like receptor 4 (TLR4)-elicited innate monocyte inflammation was important for IL21+ TFH-like cell induction in tumors, and activation of STAT1 and STAT3 was critical for TFH-like cell polarization in this process. Importantly, the TFH-like cells operated in IL21-IFNγ-dependent pathways to induce plasma cell differentiation and thereby create conditions for protumorigenic M2b macrophage polarization and cancer progression. Thus, induction of TFH-like cells links innate inflammation to immune privilege in tumors. SIGNIFICANCE: We identified a novel protumorigenic IL21+ TFH-like cell subset with a CXCR5-PD-1- BTLA-CD69hi tissue-resident phenotype in hepatoma. TLR4-mediated monocyte inflammation and subsequent T-cell STAT1 and STAT3 activation are critical for TFH-like cell induction. TFH-like cells operate via IL21-IFNγ pathways to induce plasma cells and create conditions for M2b macrophage polarization. Cancer Discov; 6(10); 1182-95. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 1069.