Tumor-derived products induce Il-1 a, Il-1 b, Tnf a, and Il-6 gene expression in murine macrophages: distinctions between tumor- and bacterial endotoxin-induced gene expression.

The ability of progressing tumors to regulate host physiology is an important consideration in our understanding of tumor-host relationships. Previous data indicated that several lines of murine sarcoma cells produced one or more activities that were able to regulate both Il-1 a and Il-1 b gene transcription in macrophages (MO). We now describe an indepth analysis using Northern analysis and bioassays and show that two of these tumors produce one or more activities that when incubated with peritoneal MO result in the transcription of the Il-1a, Il-1 b, Tnf a, and Il-6 genes. Concordant with the Northern analyses was the finding that interleukin-1 (IL-1) and tumor necrosis factor (TNF) biological activities were detected in lysates of induced MO, fixed MO, and supernates of MO cultures. Induction of gene expression was shown to be distinct from that induced by bacterial endotoxin or lipopolysaccharide by a number of criteria. The data suggest that tumor cell products may play an important role in regulating several host physiological processes, particularly those involving Il-1a, Il-1 b, Tnf a, and Il-6 gene expression.

The potential role of the macrophage colony-stimulating factor, CSF-1, in inflammatory responses: characterization of macrophage cytokine gene expression.

In this report we report that recombinant human monocyte-macrophage colony-stimulating factor-1 (CSF-1) induces resident murine peritoneal cells (PCs) to transcribe several inflammatory cytokine genes, including interleukin (IL)-1 alpha, IL-1 beta, IL-6, and granulocyte-macrophage CSF in a dose-dependent and time-related manner. Peak mRNA levels were seen between 4 and 6 h. CSF-1 did not modulate the expression of tumor necrosis factor-alpha mRNA. The serum content of the culture medium appeared to regulate both the extent of CSF-1-induced gene transcription and the adherence properties of the cells. Decreasing the serum concentration significantly reduced CSF-1-induced transcription and was associated with the rapid spreading of the majority of the adherent cells. This reduced sensitivity to CSF-1 was paralleled by a markedly lower levels of c-fms mRNA encoding the CSF-1 receptor. Induced gene transcription was followed by the release of large quantities of IL-6 only. IL-1 activity remained associated with the cells. Neither supernatant nor cell lysate granulocyte-macrophage CSF activity was inducible above the low levels associated with control cultures. Evidence that the mononuclear phagocytes, as opposed to B or T cells, were the targets of CSF-1 was obtained in two ways: (1) PCs from B6 scid/scid and NOD scid/scid mice consisting of 78-86% MAC-1+, F4/80+ cells and few B or T cells, as shown by flow cytometry analysis, released 5- to 10-fold more IL-6 in response to CSF-1 stimulation than B6 PCs, which contained approximately 30% double-positive cells, and (2) pretreatment of B6 PCs with antibodies to the CSF-1 receptor blocked the CSF-1-induced secretion of IL-6. These data suggest that CSF-1 primes noninflammatory mononuclear phagocytes for a role in inflammatory responses but does not provide the necessary signals for either secretion or translation of all cytokines equally.

Synergistic interaction of bacterial lipopolysaccharide and the monocyte-macrophage colony-stimulating factor: potential quantitative and qualitative changes in macrophage-produced cytokine bioactivity.

In this brief definitive report, we show that over a 6-h period and under serum-free conditions, recombinant monocyte-macrophage colony-stimulating factor 1 (rCSF-1) and lipopolysaccharide (LPS) synergize and induce macrophages to express higher levels of mRNA for interleukin 1 alpha (IL-1 alpha), IL-1 beta, tumor necrosis factor alpha (TNF-alpha), and IL-6 and to release more bioactivity than macrophages treated with LPS alone. This synergy was regulated by the amount of LPS in the culture medium. Paraformaldehyde-fixed macrophages like-wise showed augmentation of IL-1 activity, but whereas all of the bioactivity associated with the fixed macrophages could be neutralized by anti-IL-1 alpha antibody only approximately 40% of the supernate activity could be attributed to IL-1 alpha. Preliminary data suggest that the augmenting effect induced by CSF-1 cannot be explained solely on a quantitative basis because the addition of rIL-1 alpha to supernates of macrophages treated with LPS alone or with the combination of LPS and CSF-1 resulted in an increase in thymocyte mitogenic activity to a level that could not be explained on an additive basis. Although the supernates contained TNF and IL-6, antibody neutralization assays made it unlikely that these were directly responsible for the augmenting effect. These results suggest that CSF-1 not only enhances basic genetic responses induced by LPS alone but also may induce a mechanism that amplifies cytokine bioactivity.

CSF-1 (M-CSF) differentially sensitizes mononuclear phagocyte subpopulations to endotoxin in vivo: a potential pathway that regulates the severity of gram-negative infections.

CSF-1 is known to prime mononuclear phagocytes (MNP) for inflammatory stimuli in vitro. We hypothesized that CSF-1 in vivo can sensitize the host to the increased production of endotoxic shock mediators such as tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6). Indeed, when CSF-1-primed mice were challenged with lipopolysaccharide (LPS), increased levels of serum IL-6 and TNF-alpha were detected. Both intravenous and intraperitoneal injections of CSF-1 resulted in increased sensitivity to LPS challenge, which induced maximum increases in serum IL-6 when administered via the intraperitoneal route. The peak serum IL-6 production in control and CSF-1-primed mice occurred 2-3 h after LPS injection, whereas that of TNF-alpha occurred by 1-2 h. When peripheral blood leukocytes, spleen cells, and resident peritoneal cells (PC) were isolated from CSF-1-primed mice injected with LPS, only the PC were shown to release IL-6 constitutively and none released TNF-alpha. A comparison of mRNA isolated from various cells and tissues after intraperitoneal CSF-1 priming indicated that only PC expressed IL-6 mRNA, whereas PC, liver, and spleen expressed TNF-alpha mRNA. All tissues showed increased levels of IL-6 and TNF-alpha mRNA in response to LPS challenge. Only liver and kidney showed an enhanced level of IL-6 expression in CSF-1-primed mice challenged with LPS, whereas liver, lung, and kidney showed enhanced TNF-alpha expression. These data indicate that CSF-1 primes tissue MNP but not circulating MNP to transcribe mRNA and release IL-6 and TNF-alpha. Overall, the data suggest that CSF-1 plays an important role in regulating the sensitivity of the host to the pathophysiological effects of endotoxin.

CSF-1 regulation of Il6 gene expression by murine macrophages: a pivotal role for GM-CSF.

We test the hypothesis that the monocyte-macrophage colony-stimulating factor (CSF-1 or M-CSF) plays a major role in the inflammatory responses of Mphi by acting as a priming agent that heightens their responsiveness to secondary stimulation by other mediators. We previously reported that CSF-1 induced peritoneal Mphi (PMphi) to transcribe several genes including interleukin-6 (Il6) and granulocyte-macrophage colony-stimulating factor (Csfgm). It was reported that the Il6 and Csfgm genes were individually regulated by different pathways but it was not clear to what extent the two genes interacted during Mphi-mediated inflammatory responses. We now show that CSF-1 induces the release of bioactive GM-CSF from mouse resident PMphi. GM-CSF induces Il6 gene expression and synergizes with CSF-1 to induce the release of large amounts of IL-6. PMphi from C57BL/6J-Csfgm(null) mice were shown to release minimal IL-6 in response to CSF-1 and to express a much reduced response to the highly stimulatory combination of CSF-1 and lipopolysaccharide (LPS). Exogenous recombinant GM-CSF restored the IL-6 response of GM-CSF null PMphi to a great extent but not completely. As controls, three other recombinant proteins were tested but of these only tumor necrosis factor alpha (TNF-alpha) was shown to synergize with both CSF-1 and GM-CSF. Using PMphi from mice deficient in the expression of the Il6 gene, it was shown that they released two- to threefold more GM-CSF in response to CSF-1 than their control counterparts. However, an exogenous supply of recombinant IL-6 had no effect on GM-CSF release. The data indicate that the pathways regulating Il6 gene expression are under the control of a complex network of cytokine interactions involving at least CSF-1, GM-CSF, and TNF-alpha, with the added possibility that IL-6 may exert modulatory activity within this network.

Modifications of the guanidine hydrochloride procedure for the extraction of RNA: isolation from a variety of tissues and adherent/nonadherent cell types.

In a previous report dealing with the guanidine hydrochloride protocol for the extraction of RNA from mouse peritoneal macrophages, we identified a major source of RNA-degrading activity and showed that its removal early in the extraction procedure resulted in a more dependable method for the recovery of high-quality RNA. This report extends these findings and demonstrates the general applicability of the technique to a variety of fresh or frozen adherent cell types, cell suspensions and tissues, further highlighting stages at which degradation is most likely to occur and how to avoid a variety of pitfalls associated with the extraction procedure.

Stability of RNA isolated from macrophages depends on the removal of an RNA-degrading activity early in the extraction procedure.

Ubiquitous RNases are the usual causes of RNA degradation on its isolation from mammalian cells. Using guanidine hydrochloride for the extraction of RNA from mouse peritoneal macrophages, we identify a major source of RNA-degrading activity, the stage of the extraction procedure at which this activity may be detected and show that its removal early in the extraction leads to a more dependable method for the recovery of high quality RNA.

The therapeutic efficacy of murine anti-tumor T cells: freshly isolated T cells are more therapeutic than T cells expanded in vitro.

Adoptive immunotherapy (AIT) involving transfer of tumor-sensitized T lymphocytes in combination with cyclophosphamide (CY)-injection results in the eradication of the C57BL/6J (B6) rhabdomyosarcoma, 76-9 and is associated with the accumulation of a large number of tumor-infiltrating lymphocytes (TIL). Using immune spleen cells (ISC) from B6 and congenic B6. PL. Thy-1a mice, it was shown that most (> or = 97%) of the TIL were donor-derived. This in situ increase in donor-derived T cells was confirmed by using positively-selected Thy- 1.1+ and Thy- 1.2+ TIL for AIT after isolating them from regressing tumors and expanding them in rIL-2. The extent of CD8+ TIL expansion in vivo correlated with the numbers of TIL adoptively transferred and this in turn determined the degree of anti-tumor effects. It was evident, however, that these in vitro-expanded TIL expressing mRNA for TNF alpha and IFN gamma were qualitatively different and therapeutically less efficacious than the T cells associated with ISC or with freshly-isolated TIL. Unlike freshly isolated TIL that expressed specific cytotoxicity towards the 76-9 targets in vitro, IL-2 expanded TIL killed 76-9 cells and unrelated tumor targets to the same extent. A cytotoxic CD8+ T cell line derived from ISC and selected for activity against the 76-9 tumor cells showed no therapeutic efficacy. The data suggest that, in this tumor model, expansion of CD8+ T cells in vitro selects against anti-tumor efficacy.

Intratumor gene expression after adoptive immunotherapy in a murine tumor model. Regulation of messenger RNA levels associated with the differential expansion of tumor-infiltrating lymphocytes.

The aim of this paper was to show that the adoptive immunotherapy (AIT) of established tumors resulted in the activation of defined lymphocyte-associated genes at the site of rejection. C57BL/6J mice bearing the moderately immunogenic syngeneic MCA/76-9 sarcoma received combination therapy 10 days after tumor cell implantation. This consisted of a single i.p. injection of cyclophosphamide (CY) followed by the i.v. injection of tumor-sensitized T cells (CY/AIT). The previously observed in situ differential expansion of tumor-infiltrating lymphocytes (TIL) was associated with a parallel modulation of CD4 (L3T4) and CD8 Ag expression. Flow cytometric analysis indicated that the CD8+ TIL appeared to contain two subpopulations during the reported proliferative phase, but by day 8 after CY/AIT the cells were composed of a single bright population. The CD4+ TIL similarly appeared to show two subpopulations, but in contrast to the CD8+ TIL there was a shift to a predominantly less bright single population by day 8. The expression of lymphocyte genes (Ly-2 and Ly-4 encoding the CD8 and CD4 Ag, respectively, IL-2, IL-2R, IFN-gamma, and IL-6) was analyzed by Northern hybridization using RNA extracted from whole tumor tissue. Progressing tumors expressed only low and relatively constant levels of mRNA for all of the genes except Ly-2 over a 19-day period. In contrast, there were considerable temporal fluctuations in mRNA levels depending on whether the mice had received CY or CY/AIT, but it was apparent that CY/AIT induced the more dramatic changes as far as Ly-2, Ly-4, IL-2, and IFN-gamma mRNA levels were concerned. A preliminary survey of cytokine bioactivity released by tumor-associated cells isolated 9 days after CY/AIT indicated that both IFN-gamma and IL-6 activities were released by the cells, but not IL-2, despite the relatively high levels of IL-2 mRNA. These data provide evidence that the differential expansion of TIL after CY/AIT is accompanied by well defined changes in the levels of mRNA-encoding TIL membrane Ag and lymphokine genes and are concordant with the view that amplified anti-tumor immune responses occur after AIT.

Differential in situ expansion and gene expression of CD4+ and CD8+ tumor-infiltrating lymphocytes following adoptive immunotherapy in a murine tumor model system.

In previous reports, we demonstrated that adoptively transferred T cells homed to the tumor site (among other sites) and that amplification of immune responses occurred in situ leading to the generation of cytotoxic CD8+ tumor-infiltrating lymphocytes (TIL) and macrophages. The present report extends these findings and shows that following adoptive immunotherapy (AIT) of mice bearing the immunogenic transplanted methylcholanthrene-induced rhabdomyosarcoma (MCA/76-9) there was a differential expansion of CD4+ and CD8+ TIL, the numbers peaking on days 6 and 8, respectively. At this time, CD8+ TIL accounted for the majority of Thy-1+ cells. Northern analyses of RNA extracted from positively selected (by panning) Thy-1+, CD8+ and CD4+ TIL isolated 8 days after AIT indicated the following: in five separate experiments, CD4+ cells expressed three- to sixfold more interleukin (IL)2 mRNA and six- to eightfold more IL6 mRNA than CD8+ cells, while CD8+ TIL expressed three- to sixfold more IL2 receptor (IL2R) mRNA and four- to sixfold more interferon-gamma mRNA than CD4+ cells. TIL cultured in 10% fetal bovine serum failed to release IL2 over a 24-h period, whereas both IL6 and interferon-gamma activities were demonstrable. The level of IL2R mRNA expression was reflected by a vigorous proliferative response of CD8+ TIL to exogenous recombinant IL2 and only a low response by CD4+ cells suggesting that most of the CD4+ TIL were in the resting stage. This was confirmed when it was shown that the incubation of panned CD4+ TIL with IL2 supplemented with irradiated spleen cells and "spent" 76-9 tumor culture supernatant (as a source of antigen) induced expansion of TIL resulting in a population consisting of greater than 90% CD4+ TIL. The overall data suggest that the relatively deactivated state of the CD4+ TIL at this particular time reflects the status of the rejection process in terms of the absence or low concentration of stimulating tumor-associated antigen.

Qualitative and quantitative intratumoral changes in gene expression following cyclophosphamide injection and the adoptive transfer of T cells: the potential contribution of tumor-associated macrophages.

Adoptive immunotherapy (AIT) of mice bearing the MCA/76-9 rhabdomyosarcoma in combination with cyclophosphamide (CY) injection results in the permanent regression of tumors. This report is concerned with changes in the tumor-associated macrophage (TAM) population and the influence of both CY injection and CY/AIT on their potential functions. Sequential analyses of FcR, MAC-I and Class-II MHC antigen expressed by tumor-associated cells (TAC) showed that CY injection or CY/AIT induced marked increases in the proportions of all 3 parameters as compared with the relatively stable levels in progressing tumors. These changes were time- and treatment-related. The mean MAC-I fluorescence (antigen density per cell) increased nearly 2-fold by 48 hr after CY injection, regardless of subsequent AIT. In contrast, the density of Class-II antigen per cell declined by as much as 75% within 48 hr after CY injection and did not recover by 7 days. This initial decline was also seen after CY/AIT and was followed by a rapid recovery to near-normal values by day 7. Northern analysis of RNA isolated from whole tumor tissue indicated wide fluctuations in expression of the typical macrophage genes encoding the proteins MAC-I, IL-I alpha, IL-I beta, TNF alpha, IA beta and c-fms. However, with the exception of MAC-I and IL-1 alpha/IL-1 beta mRNA, the modifications appeared to be qualitative rather than representing changes in the proportions of TAM. The data suggest that the changes in membrane antigen and gene expression by TAM reflect a complex interaction between TAM and their environment, in particular tumor cells and tumor-infiltrating lymphocytes. In addition, it is evident that CY injection per se is responsible for defined fundamental changes that presumably influence the outcome of AIT.

CSF-1-induced and constitutive Il6 gene expression in mouse macrophages: evidence for PKC-dependent and -independent pathways.

It has been recently shown that CSF-1 enhanced the constitutive expression of the Il6 gene in resident mouse peritoneal macrophages (PM phi) but little is known about the pathways involved. In this report, we show that both constitutive and CSF-1-induced IL-6 release were enhanced and prolonged in the presence of the PKC inhibitors, staurosporine (SP) and its derivative, GF-109203X. Enhancement of constitutive IL-6 release required higher concentrations of inhibitors, while enhanced CSF-1-induced release was diminished when inhibitor concentrations exceeded defined limits. SP was also shown to activate constitutive IL-6 release by blood monocytes and elicited PM phi but had no effect on their responsiveness to CSF-1. Activation of PKC by exposure of resident PM phi to phorbol myristate acetate (PMA) also resulted in enhanced IL-6 release and PMA was shown to synergize with CSF-1. These data indicate that CSF-1 does not induce Il6 gene expression by amplifying the constitutive pathway in all mononuclear phagocyte subpopulations. It exerts its effects independently of PKC, which may activate Il6 gene expression in its own right by an alternative pathway. While CSF-1 and PKC are involved in separate pathways, the synergistic IL-6 response seen when PMA and CSF-1 interact suggests convergence of the two pathways. It is also apparent that multiple PKs, excluding PKC, may be involved in repressing constitutive and CSF-1-induced Il6 gene expression.

Priming of mouse macrophages with the macrophage colony-stimulating factor (CSF-1) induces a variety of pathways that regulate expression of the interleukin 6 (Il6) and granulocyte-macrophage colony-stimulating factor (Csfgm) genes.

Recent data have indicated that resident mouse peritoneal macrophages (PMo) transcribed the interleukin 6 (Il6) and granulocyte-macrophage colony-stimulating factor (Csfgm) genes in response to stimulation with the monocyte-macrophage colony-stimulating factor (CSF-1) but only Il6 mRNA was translated into secreted protein. In this paper, we extend these observations. It is shown that resident PMo incubated with protein kinase (PK)C inhibitors, staurosporine (SP) and its derivative GF109203-X, showed a several fold increase in the levels of Il6 mRNA in control and CSF-1-primed PMo and a parallel release of large amounts of protein. In contrast, SP was shown to have no effect on the release of GM-CSF from control or CSF-1-primed PMo, although it increased by approximately twofold the amount of Csfgm mRNA in CSF-1-primed Mo. When SP was added 4 h after CSF-1 priming to block CSF-1-induced protein kinase pathways, an increased amount of IL-6 release was again seen but without any increase in Il6 mRNA levels. Under these conditions, Csfgm gene expression was relatively unaffected. Activation of PKC by phorbol myristate acetate (PMA) also resulted in increased Il6 gene expression by control and CSF-1-primed PMo. PMA had no apparent effect on Csfgm transcription but appeared to influence translation at a low level, as measured by the release of small amounts of GM-CSF protein. The addition of lipopolysaccharide (LPS) to CSF-1-primed PMo resulted in a synergistic increase in the expression of both genes at the levels of transcription and protein release. The addition of SP to CSF-1-primed Mo before LPS, however, further enhanced IL-6 release but not GM-CSF release from the cells. The data indicate that CSF-1-priming drives a number of pathways involved in the regulation of expression of both genes and renders PMo highly susceptible to appropriate secondary stimulatory agents that transform the PMo into secretory inflammatory cells.

Combination chemotherapy and IL-15 administration induce permanent tumor regression in a mouse lung tumor model: NK and T cell-mediated effects antagonized by B cells.

Previous studies have demonstrated that IL-15 administration after cyclophosphamide (CY) injection of C57BL/6J mice bearing the i.m. 76-9 rhabdomyosarcoma resulted in a significant prolongation of life. In the present study, we investigated the immune response against the 76-9 experimental lung metastases after CY + IL-15 therapy. Administration of CY + IL-15, but not IL-15 alone, induced prolongation of life and cures in 32% of mice bearing established experimental pulmonary metastases of 76-9 tumor. The CY + IL-15 therapy resulted in increased levels of NK1.1+/LGL-1+ cells, and CD8+/CD44+ T cells in PBL. In vitro cytotoxic assay of PBL indicated the induction of lymphokine-activated killer cell activity, but no evident tumor-specific class I-restricted lytic activity. Survival studies showed that the presence of NK and T lymphocytes is necessary for successful CY + IL-15 therapy. Experiments using knockout mice implied that either alphabeta or gammadelta T cells were required for an antitumor effect induced by CY + IL-15 therapy. However, mice lacking in both alphabeta and gammadelta T cells failed to respond to combination therapy. Cured B6 and alphabeta or gammadelta T cell-deficient mice were immune to rechallenge with 76-9, but not B16LM tumor. B cell-deficient mice showed a significant improvement in the survival rate both after CY and combination CY + IL-15 therapy compared with normal B6 mice. Overall, the data suggest that the interaction of NK cells with tumor-specific alphabeta or gammadelta T lymphocytes is necessary for successful therapy, while B cells appear to suppress the antitumor effects of CY + IL-15 therapy.

Differential sensitivity of mouse mononuclear phagocytes to CSF-1 and LPS: the potential in vivo relevance of enhanced IL-6 gene expression.

In this report, we compared the responsiveness of subpopulations of mononuclear phagocytes (MNP) to the actions of the monocyte-macrophage colony-stimulating factor (CSF-1) and lipopolysaccharide (LPS), as measured by the expression of the IL-6 (Il6) gene. It was seen that neither monocytes nor elicited peritoneal macrophages (PMphi) responded directly to CSF-1 compared with resident PMphi that were induced to express high levels of Il6 mRNA and release IL-6 protein. Resident PMphi released basal (constitutive) amounts of IL-6, while constitutive release by monocytes and elicited PMphi was barely detectable. Monocytes and elicited PMphi expressed similar levels of sensitivity to LPS, as measured by IL-6 release, and were less reactive than resident PMphi. When CSF-1 and LPS were added simultaneously to resident PMphi, a dose-dependent synergistic release of IL-6 was seen. Elicited PMphi also responded synergistically but required higher levels of CSF-1 and LPS, while monocytes failed to respond synergistically under any conditions. A similar synergistic effect was also seen in vivo when mice were injected with CSF-1 and LPS. Under these conditions, only resident peritoneal cells were shown to release IL-6 ex vivo while blood leukocytes and spleen cells released minimal amounts. These findings indicate that the stage of differentiation/maturation of MNP may be important for the ability of CSF-1 to render the cells sensitive to secondary stimulation, such as by LPS, and determines to what extent MNP subpopulations contribute to inflammatory responses in vivo.