Mice deficient in tumor necrosis factor-alpha are resistant to skin carcinogenesis

Given the associations between chronic inflammation and epithelial cancer, we studied susceptibility to skin carcinogenesis in mice deficient for the pro-inflammatory cytokine TNF-alpha (refs. 5,6). TNF-alpha(-/-) mice were resistant to development of benign and malignant skin tumors, whether induced by initiation with DMBA and promotion with TPA or by repeated dosing with DMBA. TNF-alpha(-/-) mice developed 5-10% the number of tumors developed by wild-type mice during initiation/promotion and 25% of those in wild-type mice after repeated carcinogen treatment. TNF-alpha could influence tumor and stromal cells during tumor development. The early stages of TPA promotion are characterized by keratinocyte hyperproliferation and inflammation. These were diminished in TNF-alpha(-/-) mice. TNF-alpha was extensively induced in the epidermis, but not the dermis, in TPA-treated wild-type skin, indicating that dermal inflammation is controlled by keratinocyte TNF-alpha production. Deletion of a TNF-alpha inducible chemokine also conferred some resistance to skin tumor development. TNF-alpha has little influence on later stages of carcinogenesis, as tumors in wild-type and TNF-alpha(-/-) mice had similar rates of malignant progression. These data provide evidence that a pro-inflammatory cytokine is required for de novo carcinogenesis and that TNF-alpha is important to the early stages of tumor promotion. Strategies that neutralize TNF-alpha production may be useful in cancer treatment and prevention.

In vivo properties of monocyte chemoattractant protein-1

Monocyte chemoattractant protein-1 (MCP-1) attracts monocytes, memory T lymphocytes, and natural killer (NK) cells in vitro. Its expression has been documented in disorders characterized by mononuclear cell infiltrates, suggesting that it may contribute to the inflammatory component of such diseases as atherosclerosis, multiple sclerosis, or rheumatoid arthritis. To prove a causal association, the in vivo properties of MCP-1 must be understood. Several lines of transgenic mice have been constructed to address this question. A transgenic line in which MCP-1 expression is controlled by the MMTV-LTR expressed high levels of MCP-1 in multiple organs but showed no evidence for monocyte infiltration. Instead, these mice were more susceptible to infection by the intracellular pathogens, Listeria monocytogenes and Mycobacterium tuberculosis. These mice had high serum levels of MCP-1, suggesting that their circulating monocytes may have been desensitized or that MCP-1 stimulated a Th2-dominant response. In contrast, another model in which MCP-1 expression was controlled by the insulin promoter demonstrated a monocytic infiltrate in pancreatic islets. These results indicate that MCP-1 expression at low levels in an anatomically confined area results in monocyte infiltration, suggesting that when properly expressed, MCP-1's in vitro properties are reproduced in vivo. This justifies the examination of MCP-1-deficient mice in disease models in order to explore MCP-1's role in pathogenesis.

The beta-chemokine receptors CCR3 and CCR5 facilitate infection by primary HIV-1 isolates

We examined the ability of chemokine receptors and related G protein-coupled receptors to facilitate infection by primary, clinical HIV-1 isolates. CCR5, when expressed along with CD4, the HIV-1 receptor, allowed cell lines resistant to most primary HIV-1 isolates to be infected. CCR3 facilitated infection by a more restricted subset of primary viruses, and binding of the CCR3 ligand, eotaxin, inhibited infection by these isolates. Utilization of CCR3 and CCR5 on the target cell depended upon the sequence of the third variable (V3) region of the HIV-1 gp120 exterior envelope glycoprotein. The ability of various members of the chemokine receptor family to support the early stages of HIV-1 infection helps to explain viral tropism and beta-chemokine inhibition of primary HIV-1 isolates.

High level expression of human MCP-1 using the LCR/MEL expression system

We have expressed human monocyte chemoattractant protein-1 (hMCP-1) in preerythroid mouse erythroleukemia (MEL) C88 cells using the locus control region/MEL expression system and studied the biological activity of the purified protein in a range of in vitro experimental systems. The recombinant hMCP-1 is expressed at high levels (approximately 10 mg/liter) in this system and is modified in a manner which is very similar to native hMCP-1. We have developed a simple high-yielding two-step purification route employing dye ligand and ion exchange chromatographies which enables us to separate glycosylated and unglycosylated hMCP-1. The purified glycosylated and unglycosylated forms of hMCP-1 have equivalent biological activities in all of the assay systems tested.

Pain and quality assessment/improvement

Pain is a common symptom of acute and chronic illness and has been targeted as an area of improvement across settings and populations. Advances in the treatment of pain have created a standard of care by which quality can be assessed. The article describes the process of quality assessment and improvement (QA/I) in pain management. QA/I tools and case examples from two institutions are provided. QA/I activities based on current knowledge of pain management can improve the care provided to patients in pain.

Serologic analysis of the mouse beta chemokine JE/monocyte chemoattractant protein-1

Mouse monocyte chemoattractant protein-1 (MCP-1), previously termed JE, is a member of the beta chemokine gene family and a homologue of the human monocyte chemoattractant protein, MCP-1. Mouse rMCP-1 was used to immunize hamsters for the production of mAb. Seven mouse MCP-1-specific mAbs were characterized: two of these mAbs cross-reacted with the human MCP-1, as determined by ELISA. A sensitive and specific capture ELISA for MCP-1 quantitation, which allowed measurement of mouse MCP-1 levels in supernatants from cells stimulated with inflammatory agents, was developed. LPS-stimulated astrocytes produce the highest levels of MCP-1 (80 ng/ml); macrophages and mesangial cells produce lower levels of MCP-1 (2 to 14 ng/ml) after LPS stimulation. IL-1 and TNF-alpha stimulation also can induce low levels of MCP-1 production. Western blot analysis demonstrated that the predominant native form of mouse MCP-1 is a 30-kDa glycoprotein. Two mAbs (2H5 and 6C7) demonstrated dose-dependent neutralization of mouse MCP-1 chemotactic activity. To localize the epitope recognized by one of these neutralizing Abs, the mAb was used to bind a series of genetically engineered truncated variants of human MCP-1. The C-terminal residues 62 to 67 on human MCP-1 molecules seem to be critical to express the epitope recognized by the neutralizing 2H5 anti-MCP-1 mAb. However, multiple sites on the MCP-1 molecule seem to be critical for bioactivity. Thus, these Ab reagents provide a useful tool to explore the biology of the mouse MCP-1 beta chemokine.

Serologic analysis of the mouse beta chemokine JE/monocyte chemoattractant protein-1

Mouse monocyte chemoattractant protein-1 (MCP-1), previously termed JE, is a member of the beta chemokine gene family and a homologue of the human monocyte chemoattractant protein, MCP-1. Mouse rMCP-1 was used to immunize hamsters for the production of mAb. Seven mouse MCP-1-specific mAbs were characterized: two of these mAbs cross-reacted with the human MCP-1, as determined by ELISA. A sensitive and specific capture ELISA for MCP-1 quantitation, which allowed measurement of mouse MCP-1 levels in supernatants from cells stimulated with inflammatory agents, was developed. LPS-stimulated astrocytes produce the highest levels of MCP-1 (80 ng/ml); macrophages and mesangial cells produce lower levels of MCP-1 (2 to 14 ng/ml) after LPS stimulation. IL-1 and TNF-alpha stimulation also can induce low levels of MCP-1 production. Western blot analysis demonstrated that the predominant native form of mouse MCP-1 is a 30-kDa glycoprotein. Two mAbs (2H5 and 6C7) demonstrated dose-dependent neutralization of mouse MCP-1 chemotactic activity. To localize the epitope recognized by one of these neutralizing Abs, the mAb was used to bind a series of genetically engineered truncated variants of human MCP-1. The C-terminal residues 62 to 67 on human MCP-1 molecules seem to be critical to express the epitope recognized by the neutralizing 2H5 anti-MCP-1 mAb. However, multiple sites on the MCP-1 molecule seem to be critical for bioactivity. Thus, these Ab reagents provide a useful tool to explore the biology of the mouse MCP-1 beta chemokine.

Association of food frequency questionnaire estimates of vitamin A intake with serum vitamin A levels

To assess the validity of nutrient intake estimates from a food frequency questionnaire, the authors compared estimates of intake of preformed retinol (dietary plus supplements), beta-carotene, other active carotenoids, and total vitamin A computed from questionnaire responses with serum retinoid and carotenoid concentrations. Data were obtained from 302 male and female current or former smokers, participants in a lung cancer chemoprevention trial at the Fred Hutchinson Cancer Research Center in Seattle, Washington, during 1985-1986. Both serum beta-carotene and serum alpha-carotene were associated, although weakly, with food frequency estimates of total vitamin A intake, dietary vitamin A, beta-carotene, other carotenoids, and total carotenoids (0.18 less than or equal to r less than or equal to 0.26). Serum retinol was associated with supplementary vitamin A intake (r = 0.16). Nondietary factors were also associated with serum nutrient concentrations--in particular, cigarette smoking, alcohol intake, and body mass index. Cigarette smoking emerged as an important modifying factor of the relation between serum beta-carotene and dietary beta-carotene (r = 0.14 for current smokers, r = 0.30 for former smokers).

Micronutrient assay for cancer prevention clinical trials: serum retinol, retinyl palmitate, alpha-carotene, and beta-carotene with the use of high-performance liquid chromatography

Assay of serum levels of retinol, retinyl palmitate, alpha-carotene, and beta-carotene to assess nutritional status, to trials of retinol and/or beta-carotene to assess nutritional status, to monitor compliance with medication schedules, and to conduct toxicity surveillance. The optimal assay method for clinical trial use represents a balance between analytical power and speed/simplicity. Three such methods were evaluated by means of shared samples between two laboratories. Each method required less than 15 minutes per assay and detected all of the analytes of interest. Careful evaluation of calibration materials and procedures permitted different laboratories using different methods to produce results with an interlaboratory variability smaller than the within-laboratory variability for each separate method. Typical precisions for the analytes in serum samples are: retinol, 0.06 relative standard deviation (RSD; standard deviation divided by mean value); retinyl palmitate, 0.08 RSD; alpha-carotene, 0.15 RSD; and beta-carotene, 0.11 RSD. Application of these methods to several hundred samples indicated that retinyl palmitate and beta-carotene levels were indicative of administered retinol and beta-carotene, whereas retinol itself was not. Population variability in pretreatment serum levels of these micronutrients expressed as RSD (retinol, 0.24; alpha-carotene, 1.11; and beta-carotene, 0.98) far exceeded the analytical imprecision in these determinations, confirming that the present assays could meet the needs of current clinical intervention trials.