Fibronectin activates murine peritoneal macrophages for tumor cell destruction in the presence of IFN-gamma

Immunological aspects of head and neck cancer: biology, pathophysiology and therapeutic mechanisms

Advanced cancer and head and neck cancer, in particular, remains a major clinical challenge with its associated morbidity and inevitable mortality. Local control of early disease is achievable in many solid tumours with current surgical and radiotherapeutic techniques but metastatic disease is associated with poor outcome and prognosis. It is known that, by the time of presentation, many patients will already have occult microscopic metastatic disease, and surgery and radiotherapy will not result in long-term survival. What little effect modern chemotherapeutic agents have on microscopic disease is, however, limited by systemic toxicity and multi-drug resistance. Immune surveillance is postulated to be operative in man. There is evidence, however, that patients with progressive tumour growth have failure of host defences both locally and systemically. Various possible defects and tumour escape mechanisms are discussed in the review. Immunotherapy and, in particular adoptive T cell therapy and DC therapy, show promise as putative tumour-specific therapy with clinical benefits. These techniques are undergoing development and evaluation in phase 1 clinical trials. Preliminary data suggest that the treatments are well tolerated. Unfortunately, there is limited evidence of significant and prolonged improvements in clinical outcome. Further developments of beneficial protocols (adjuvants, mode and frequency of vaccination etc) and multicentre studies of the use of immunotherapy in cancer are now required.

Gene expression in IFN-gamma-activated murine macrophages

Macrophages are critical for natural immunity and play a central role in specific acquired immunity. The IFN-gamma activation of macrophages derived from A/J or BALB/c mice yielded two different patterns of antiviral state in murine hepatitis virus 3 infection, which were related to a down-regulation of the main virus receptor. Using cDNA hybridization to evaluate mRNA accumulation in the cells, we were able to identify several genes that are differently up- or down-regulated by IFN-gamma in A/J (267 and 266 genes, respectively, up- and down-regulated) or BALB/c (297 and 58 genes, respectively, up- and down-regulated) mouse macrophages. Macrophages from mice with different genetic backgrounds behave differently at the molecular level and comparison of the patterns of non-activated and IFN-gamma-activated A/J or BALB/c mouse macrophages revealed, for instance, an up-regulation and a down-regulation of genes coding for biological functions such as enzymatic reactions, nucleic acid synthesis and transport, protein synthesis, transport and metabolism, cytoskeleton arrangement and extracellular matrix, phagocytosis, resistance and susceptibility to infection and tumors, inflammation, and cell differentiation or activation. The present data are reported in order to facilitate future correlation of proteomic/transcriptomic findings as well as of results obtained from a classical approach for the understanding of biological phenomena. The possible implication of the role of some of the gene products relevant to macrophage biology can now be further scrutinized. In this respect, a down-regulation of the main murine hepatitis virus 3 receptor gene was detected only in IFN-gamma-activated macrophages of resistant mice.

Decorin reverses the repressive effect of autocrine-produced TGF-beta on mouse macrophage activation

Several cytokines or growth factors induce macrophages to proliferate, become activated, differentiate, or die through apoptosis. Like the major macrophage activator IFN-gamma, the extracellular matrix protein decorin inhibits proliferation and protects macrophages from the induction of apoptosis. Decorin enhances the IFN-gamma-induced expression of the IAalpha and IAbeta MHC class II genes. Moreover, it increases the IFN-gamma- or LPS-induced expression of inducible NO synthase, TNF-alpha, IL-1beta, and IL-6 genes and the secretion of these cytokines. Using a number of extracellular matrix proteins, we found a negative correlation between adhesion and proliferation. However, the effects of decorin on macrophage activation do not seem to be mediated through its effect on adhesion or proliferation. Instead, this proteoglycan abolishes the binding of TGF-beta to macrophages, as shown by Scatchard analysis of (125)I-labeled TGF-beta, which, in the absence of decorin, showed a K(d) of 0.11 +/- 0.03 nM and approximately 5000 receptors/cell. This was confirmed when we treated macrophages with Abs to block the endogenously produced TGF-beta, which enhanced macrophage activation in a way similar to decorin. The increase in activation mediated by decorin demonstrates that macrophages are under negative regulation that can be reversed by proteins of the extracellular matrix.

Type I collagen is a non-adhesive extracellular matrix for macrophages

Macrophages adhere to a variety of substrata including plastic, glass or an extracellular matrix either in a highly specific manner or through less specific mechanisms. We investigated the effect of type I collagen, the most abundant protein in animal tissues, on the adhesion of macrophages derived from a human monoblastic cell line U937. Macrophages were observed to adhere very weakly to type I collagen and aggregate, whereas they adhered firmly and spread on plastic, bovine serum albumin or fibronectin. On the adhesive substratum, the lower surface of the macrophages was flat and closely apposed to the substratum. In contrast, macrophages adhered on type I collagen at the tip of cell processes. The adhesion of macrophages to plastic, bovine serum albumin or fibronectin was associated with the induction of tyrosine phosphorylation of a variety of proteins including a major protein band at 66 kDa. In contrast, the induction of tyrosine phosphorylation was markedly reduced when the macrophages were cultured on type I collagen. Two members of the src family, Lyn and Hck, were tyrosine phosphorylated in firmly adhered macrophages but not in macrophages cultured on type I collagen. These results suggest that the adhesion of macrophages is associated with the tyrosine phosphorylation of a variety of proteins including Lyn and Hck, and that type I collagen serves as a non-adhesive substratum for macrophages, resulting in an altered signal transduction.

Spatiotemporal changes of fibronectin, tenascin-C, fibulin-1, and fibulin-2 in the skin during the development of chronic contact dermatitis

In order to elucidate how chronic inflammation affects the organization of the extracellular matrix in the skin, a prolonged allergic contact dermatitis was induced in a mouse by repeated application to the ear of 2,4-dinitrofluorobenzene every 3 d for 66 d. Subsequently, the spatiotemporal changes of fibronectin, tenascin-C, fibulin-1, and fibulin-2 in the skin were examined. In the acute phase of inflammation (day 3-day 12), the amount of fibronectin and tenascin-C increased markedly and were degraded, whereas the amount of fibulin-2 changed slightly. Abundant deposition of tenascin-C was observed in the connective tissue. Fibulin-1 and fibulin-2 distributed as fine fibrils. In contrast, the amounts of fibronectin and tenascin-C decreased and their degradation was suppressed in the chronic phase (day 15-day 66), but the amount of fibulin-2 increased. Tenascin-C was observed mainly at and underneath the epidermal basement membrane. In the subepidermal region, many fibulin-2-positive microfibrils were distributed. The amount and distribution of fibulin-1 did not change markedly in either phase. MMP-like enzymes of 62 kDa, probably activated MMP-2, were upregulated in the chronic phase, whereas components of 92, 85, or 67 kDa were highly induced in the acute phase. These results suggest that chronic inflammation in allergic contact dermatitis is associated with temporal changes in the expression, deposition, and degradation of inducible extracellular matrix components.

Cytokine repertoire during maturation of monocytes to macrophages within spheroids of malignant and non-malignant urothelial cell lines

Terminal maturation of human blood monocytes to macrophages (MAC) in vivo is believed to be important for the morphology, antigen expression and functional activity of the resulting MAC population. This process is modulated by the specific tissue micro-environment to which blood monocytes migrate upon leaving the vasculature. Tumor-associated macrophages (TAM) are a special type of MAC, and little is known about the modulating capacity of the tumor environment on monocyte-to-MAC differentiation. By co-culturing 3-dimensional multicellular spheroids (MCS) of the urothelial-bladder-carcinoma cell lines J82 and RT4 with human monocytes/MAC we generated TAM in vitro. For comparison, monocytes/MAC were co-cultured with the non-tumorigenic urothelial cell line HCV29. The effects on monocyte differentiation were analyzed, particularly with respect to cytokine release. Monocyte maturation was modulated within the tumor spheroid dependent upon the tumor cell type. Monocytes co-cultured with MCS of the poorly differentiated J82 carcinoma spontaneously produced high amounts of IL-1beta and IL-6, but only low amounts of TNF-alpha, which could be further increased by the addition of LPS. This cytokine pattern is characteristic for monocytes and remained constant for up to 8 days in J82-MCS co-cultures. However, in RT4-MCS and HCV29-MCS co-cultures, the initial cytokine pattern changed and after 8 days corresponded well to that of MAC differentiated in vitro without tumor contact. In addition to functional parameters, we analyzed the morphology of J82-MCS-TAM and found that they displayed a monocyte-like morphology. Our data indicate that (1) tumor cells can influence monocyte-to-MAC differentiation, giving rise to TAM with monocyte-specific phenotypic properties; and (2) this capacity is dependent on the type of tumor cell.

Augmentation of recombinant fibronectin polypeptide CH50 on the antitumor function of macrophages

We prepared an anti-metastatic polypeptide, recombinant fibronectin polypeptide CH50, and finished the preliminary identification of its functions. In this paper, we studied the effect of this polypeptide on the function of macrophages. CH50 can significantly augment the production of nitric oxide(NO) by macrophages in a dose-dependent manner. The continuous presence of CH50 had a much stronger effect. In the presence of CH50, the cytotoxicity of macrophages to melanoma B16/F1 cells was significantly enhanced, and a stronger effect was obtained if CH50 was present continuously. CH50 polypeptide and IFN-gamma have a synergistic effect on the production of NO by macrophages and the cytotoxicity of macrophages on tumor cells. In the in vivo experiments, CH50 can inhibit the growth of tumor cells, and have a better effect in the presence of IFN-gamma. Our results suggest that recombinant fibronectin polypeptide CH50 has two functions: one is to inhibit the metastasis of tumor cells, and the other one is to augment the function of macrophages. And this polypeptide will be potentially useful in tumor therapy.

Three-dimensional co-culture of human monocytes and macrophages with tumor cells: analysis of macrophage differentiation and activation

Here we report on an experimental system for generating TAM in vitro by culturing human MO and MO-derived macrophages (MAC) within 3-dimensional multicellular tumor spheroids (MCS). MO as well as MO-derived MAC migrate into tumor spheroids and spread throughout the entire spheroid within 16 hr. In contrast, fibroblast-spheroids were not infiltrated. The regular expression of MAC maturation-associated antigens on infiltrating MO was suppressed within MCS of the undifferentiated bladder carcinoma line J82 with regard to carboxypeptidase M (CPM), MAX.3 antigen and CD105. However, MAC within spheroids of highly differentiated papillary RT4 cells failed only the single antigen CD51, whereas MAC expressed the complete maturation-associated phenotype within non-tumorigenic HCV29 spheroids. Interestingly, the suppressive effect of J82 carcinoma cells could only be observed in 3-dimensional but not in monolayer cultures. The J82-MCS induced suppression of CPM and MAX.3 expression was only seen to be operative on infiltrating blood MO: MO first differentiated for 2 days and subsequently co-cultured with J82-MCS showed normal expression of MAX.3 and CPM within the spheroid. Besides the modulation of MAC phenotype, the cytokine response of intraspheroidal MAC was analyzed: upon co-culture MO secreted high IL-1beta and IL-6 but low amounts of TNF-alpha as compared to MAC. This MO typical cytokine pattern remained constant for up to 8 days in culture, again indicating a disturbed MO to MAC maturation within tumor spheroids. In conclusion, a 3-dimensional interaction with tumor cells in vitro results in significant changes in the phenotype and function of the spheroid-associated MO and MAC.