High expression of tumor-infiltrating macrophages correlates with poor prognosis in patients with diffuse large B-cell lymphoma

Prognostic influence of macrophages in patients with diffuse large B-cell lymphoma: a correlative study from a Nordic phase II trial

The prognostic impact of the tumor microenvironment in diffuse large B-cell lymphoma has not been systematically assessed. We analyzed mRNA and antigen expression of monocytes, macrophages, lymphocytes, dendritic and natural killer cells in pretreatment tumor samples of patients with high-risk diffuse large B-cell lymphoma using gene expression microarray and immunohistochemistry. The patients were treated in a Nordic phase II study with dose-dense chemoimmunotherapy and central nervous system prophylaxis. Of the studied markers for non-malignant inflammatory cells, CD68 expression and CD68(+) macrophage counts correlated with favorable outcome. Five-year progression-free survival rates were 83% and 43% for the patients with high and low CD68 mRNA levels, respectively (P=0.007), while overall survival rates were 83% and 64%, respectively (P=ns). The patients with high CD68(+) macrophage counts had better 5-year progression-free survival (74% versus 40%; P=0.003) and overall survival (90% versus 60%; P=0.009) than the patients with low macrophage counts. Low CD68(+) macrophage count retained its prognostic impact on overall survival with age-adjusted International Prognostic Index [RR=5.0 (95% CI 1.024-19.088); P=0.017]. The findings were validated in three independent cohorts of patients treated with chemoimmunotherapy. In contrast, in patients treated with chemotherapy, high CD68(+) macrophage count was associated with poor progression-free survival (40% versus 72%; P=0.021) and overall survival (39% versus 72%; P=0.015). Together, the data suggest that macrophages exhibit a dual, treatment-specific role in diffuse large B-cell lymphoma. For the patients treated with chemoimmunotherapy, high pretreatment CD68 mRNA levels and CD68(+) macrophage numbers predict a favorable outcome.

Microvascular density, CD68 and tryptase expression in human diffuse large B-cell lymphoma

Diffuse Large B-cell Lymphoma (DLBCL) is the most common form of Non-Hodgkin lymphoma characterized by clinical and biological heterogeneity attributable both to the tumor cells and the complex tumor-microenvironment surrounding them. Tumor-associated macrophages (TAMs) and mast cells are two major components of the tumor inflammatory infiltrate with a definite role in enhancing tumor angiogenesis. In this study, we have investigated CD68 and tryptase expression and their relationship with microvascular density (MVD) in chemo-resistant and chemosensitive patients affected by DLBCL. CD68 and tryptase expression as well as MVD were increased in chemo-resistant patients when compared with chemosensitive patients. Tryptase expression showed a positive correlation with MVD, supporting a role for mast cell in DLBCL tumor angiogenesis, while CD68 correlation with MVD was not significant, indicating a different role for TAMs than angiogenesis in DLBCL.

High intratumoral macrophage content is an adverse prognostic feature in anaplastic large cell lymphoma

AIMS

Macrophage infiltration has been associated with prognosis in several cancers, including lymphoma, but has not been assessed systematically in anaplastic large cell lymphoma (ALCL). The aim of the study was to correlate expression of the macrophage-associated antigens CD68 and CD163 with pre-therapeutic parameters and outcome in a cohort of treatment-naive ALCL patients.

METHODS AND RESULTS

Pre-therapeutic tumour specimens from 52 patients with ALCL were included in a tissue microarray. The intratumoral macrophage content was assessed by immunohistochemical staining for CD68 and CD163, and quantified using digital image analysis. Anaplastic lymphoma kinase (ALK)-positive patients were significantly younger and had a favourable outcome compared with ALK-negative ALCL patients (median age: 42 versus 59 years; P = 0.008). However, ALK expression was not a significant predictor when adjusting for age. Although classical risk factors were distributed evenly between the compared groups, high intratumoral content of CD68 and/or CD163 correlated with poor outcome, in both univariate and multivariate analyses. High intratumoral CD163 content showed the strongest adverse association with both overall and progression-free survival in ALK-negative patients (P < 0.001).

CONCLUSIONS

A high content of intratumoral CD68- and/or CD163-positive macrophages correlates with an adverse outcome in ALK-negative ALCL.

Role of tumor-infiltrating CD11b+ antigen-presenting cells in the progression of gastric cancer

BACKGROUND

Tumor-infiltrating antigen-presenting cells (APCs), involving tumor-associated macrophages and tumor-infiltrating dendritic cells, play an important role in tumor immunity and immune escape. The aim of this study was to determine whether tumor infiltrating CD11b(+) APCs may affect tumor progression and clinical outcome.

METHODS

The immunohistochemical analysis was used to evaluate the expression of CD11b, FOXP3, and CD8 in 214 gastric cancer tissues. Concentrations of immunosuppressive cytokines in medium conditioned by gastric cancer cells were measured by enzyme-linked immunosorbent assay. Effects of addition of tumor-conditioned media on CD11c(+) cells were examined by flow cytometry.

RESULTS

Almost all tumor-infiltrating CD11b(+) cell expressed CD11c and was considered to be APCs. High CD11b(+) cell infiltration was significantly correlated with huge tumor, positive venous invasion, lymph node metastasis, and tumor, node, metastasis stage. Patients with high CD11b(+) cell infiltration had a poorer surgical outcome than those with low CD11b infiltration. Multivariate analysis revealed that CD11b(+) cell infiltration was one of the independent prognostic factors. Tumor-conditioned medium obtained from several gastric cancer cell lines contained immunosuppressive cytokines, transforming growth factor-beta, interleukin-10, and vascular endothelial growth factor. The addition of tumor-conditioned medium decreased the expression of major histocompatibility complex-II and increased the expression of CD11b and programmed death ligand 2 on CD11c(+) APCs. Infiltration of CD11b(+) cells significantly correlate with the degree of FOXP3(+) cell infiltration but not with CD8(+) cell infiltration.

CONCLUSIONS

Tumor-infiltrating CD11b(+) APCs affected local tumor cell-immune cell interactions and correlated to the poor prognosis of the patients with gastric cancer.

Prognostic impact of monocyte count at presentation in mantle cell lymphoma

An increased number of circulating monocytes at presentation has recently been associated with shorter survival in Hodgkin lymphoma, follicular lymphoma and diffuse large B cell lymphoma. This study aimed to assess the prognostic impact of the absolute monocyte count (AMC) at diagnosis in mantle cell lymphoma (MCL). AMC at diagnosis was available in 97 MCL cases recorded in the databases of the Oncology Institute of Southern Switzerland in Bellinzona (Switzerland) and the Division of Haematology of the Amedeo Avogadro University of Eastern Piedmont in Novara (Italy). With a median follow up of 7 years, the 5-year overall survival was 29% for patients with AMC >0·50 × 10(9) /l and 62% for patients with AMC ≤0·50 × 10(9) /l (P = 0·008). Elevated AMC and beta-2 microglobulin at diagnosis remained independent outcome predictors at multivariate analysis, controlling for the MCL International Prognostic Index (MIPI), and have been used to build a simple prognostic scoring system. In this relatively small and heterogeneous series an increased AMC identified poor-risk patients. Our results suggest that AMC together with the beta-2 microglobulin level might provide an inexpensive way to stratify MCL patient risk as a complement to the MIPI, which was confirmed to be a very powerful prognostic tool.

Myeloid cell receptor LRP1/CD91 regulates monocyte recruitment and angiogenesis in tumors

Recruitment of monocytes into sites of inflammation is essential in the immune response. In cancer, recruited monocytes promote invasion, metastasis, and possibly angiogenesis. LDL receptor-related protein (LRP1) is an endocytic and cell-signaling receptor that regulates cell migration. In this study, we isografted PanO2 pancreatic carcinoma cells into mice in which LRP1 was deleted in myeloid lineage cells. Recruitment of monocytes into orthotopic and subcutaneous tumors was significantly increased in these mice, compared with control mice. LRP1-deficient bone marrow-derived macrophages (BMDM) expressed higher levels of multiple chemokines, including, most prominently, macrophage inflammatory protein-1α/CCL3, which is known to amplify inflammation. Increased levels of CCL3 were detected in LRP1-deficient tumor-associated macrophages (TAM), isolated from PanO2 tumors, and in RAW 264.7 macrophage-like cells in which LRP1 was silenced. LRP1-deficient BMDMs migrated more rapidly than LRP1-expressing cells in vitro. The difference in migration was reversed by CCL3-neutralizing antibody, by CCR5-neutralizing antibody, and by inhibiting NF-κB with JSH-23. Inhibiting NF-κB reversed the increase in CCL3 expression associated with LRP1 gene silencing in RAW 264.7 cells. Tumors formed in mice with LRP1-deficient myeloid cells showed increased angiogenesis. Although VEGF mRNA expression was not increased in LRP1-deficient TAMs, at the single-cell level, the increase in TAM density in tumors with LRP1-deficient myeloid cells may have allowed these TAMs to contribute an increased amount of VEGF to the tumor microenvironment. Our results show that macrophage density in tumors is correlated with cancer angiogenesis in a novel model system. Myeloid cell LRP1 may be an important regulator of cancer progression.

Macrophages in multiple myeloma: emerging concepts and therapeutic implications

Multiple myeloma, a clonal plasma cell malignancy, has long provided a prototypic model to study regulatory interactions between malignant cells and their microenvironment. Myeloma-associated macrophages have historically received limited scrutiny, but recent work points to central and non-redundant roles in myeloma niche homeostasis. The evidence supports a paradigm of complex, dynamic and often mutable interactions between macrophages and other cellular constituents of the niche. We and others have shown that macrophages support myeloma cell growth, viability and drug resistance through both contact-mediated and non-contact-mediated mechanisms. These tumor-beneficial roles have evolved in opposition to, or in parallel with, intrinsic pro-inflammatory and tumoricidal properties. Thus, simple blockade of protective "don't eat me" signals on the surface of myeloma cells leads to macrophage-mediated myeloma cell killing. Macrophages also enhance the tumor-supportive role of mesenchymal stem/stromal cells (MSCs) in the niche: importantly, this interaction is bidirectional, producing a distinct state of macrophage polarization that we termed "MSC-educated macrophages." The intriguing pattern of cross-talk between macrophages, MSCs and tumor cells highlights the myeloma niche as a dynamic multi-cellular structure. Targeted reprogramming of these interactions harbors significant untapped therapeutic potential, particularly in the setting of minimal residual disease, the main obstacle toward a cure.

The monocytic population in chronic lymphocytic leukemia shows altered composition and deregulation of genes involved in phagocytosis and inflammation

Macrophages reside in tissues infiltrated by chronic lymphocytic leukemia B cells and the extent of infiltration is associated with adverse prognostic factors. We studied blood monocyte population by flow cytometry and whole-genome microarrays. A mixed lymphocyte reaction was performed to evaluate proliferation of T cells in contact with monocytes from patients and normal donors. Migration and gene modulation in normal monocytes cultured with CLL cells were also evaluated. The absolute number of monocytes increased in chronic lymphocytic leukemia patients compared to the number in normal controls (792 ± 86 cells/μL versus 485 ± 46 cells/μL, P=0.003). Higher numbers of non-classical CD14(+)CD16(++) and Tie-2-expressing monocytes were also detected in patients. Furthermore, we performed a gene expression analysis of monocytes in chronic lymphocytic leukemia patients, showing up-regulation of RAP1GAP and down-regulation of tubulins and CDC42EP3, which would be expected to result in impairment of phagocytosis. We also detected gene alterations such as down-regulation of PTGR2, a reductase able to inactivate prostaglandin E2, indicating immunosuppressive activity. Accordingly, the proliferation of T cells in contact with monocytes from patients was inhibited compared to that of cells in contact with monocytes from normal controls. Finally, normal monocytes in vitro increased migration and up-regulated CD16, RAP1GAP, IL-10, IL-8, MMP9 and down-regulated PTGR2 in response to leukemic cells or conditioned media. In conclusion, altered composition and deregulation of genes involved in phagocytosis and inflammation were found in blood monocytes obtained from chronic lymphocytic leukemia patients, suggesting that leukemia-mediated "education" of immune elements may also include the establishment of a skewed phenotype in the monocyte/macrophage population.

High numbers of tumor-associated macrophages correlate with poor prognosis in patients with mature T- and natural killer cell lymphomas

Various studies on lymphoma microenvironment have demonstrated the prognostic impact of tumor-associated macrophages (TAMs) in patients with B-cell lymphoma. Little is known about the correlation between TAMs and treatment outcome in mature T- and natural killer (NK) cell lymphomas. We analyzed the prognostic relevance of CD68+ TAMs by immunohistochemical analysis in 64 Chinese patients with mature T- and NK-cell lymphomas. Higher number of infiltrated TAMs was significantly related to B symptoms and extranodal involvement (p < 0.05). The TAMs content did not differ significantly between pathological subtypes. Using the mean value of TAMs per high-power field (hpf) as the cutoff point (87/hpf), 36 cases (56.2 %) were categorized as low level of TAMs content and 28 cases (43.8%) as high level. Patients with high level of TAMs content had a worse 5-year overall survival compared to those with low level (28.1 vs. 44.3 %, p = 0.039). In multivariate analysis, TAMs content remained an independent biological variable for survival distinct from the International Prognostic Index (Cox multivariate model, p = 0.009). High TAMs content indicated an adverse overall outcome in mature T- and NK-cell lymphomas. Our results show that expression of stromal TAMs may become a useful marker for prognosis of mature T- and NK-cell lymphomas.