Michael D. Lieberman

Dietary Manipulation of Methotrexate-Induced Enterocolitis

Administration of chemotherapy is limited by host toxicity, which is often manifested by severe enterocolitis. This study evaluated the effects of a liquid, elemental, chemically defined diet (ED) supplemented with 2% glutamine (Glu-ED) compared with a polypeptide diet (PPD) on the morbidity and mortality after methotrexate (MTX) administration. Fischer 344 rats (n = 80) were fed either a regular rat chow diet (RD), a 2% glycine supplemented elemental diet (Gly-ED), a 2% glutamine-supplemented elemental diet (GLU-ED), and a glycine-supplemented polypeptide diet(Gly-PPD) for 7 days prior to administration of MTX (20 mg/kg, ip). After 72 hours, eight rats per group were killed; portal vein and vena cava blood, mesenteric lymph nodes (MLN), liver, small intestine, and cecum were sampled for bacterial culture. Remaining animals were followed to calculate survival. One hundred percent of the Gly-PPD and 25% of the Glu-ED animals survived compared with 0% of the Gly-ED animals. Our data showed that ED resulted in an increased quantity of intestinal Gram-negative bacteria and diminished intestinal mucosal height and mucosal DNA/protein content. The polypeptide diet prevented intestinal mucosal atrophy, avoided MTX-induced enterocolitis and significantly improved animal survival compared with an elemental diet with or without glutamine supplementation.

Enhancement of interleukin-2 immunotherapy with L-arginine.

Nutrient substrates have been shown to enhance cell-mediated immunity, but their role as adjuvants to immunotherapy has not been previously determined. This study evaluated L-arginine as an essential substrate for optimal generation of lymphokine-ac-tivated killer (LAK) cells. This experiment also assessed supplemental dietary L-arginine as a means to potentiate the host antitumor response to interleukin-2 (IL-2) in a murine neuro-blastoma (NRB) model. A/J mice received 1% arginine or iso-nitrogenous 1.7% glycine in addition to a regular diet 14 days before subcutaneous inoculation with C1300 NRB cells. Twenty-four hours later, animals received low (1 χ 106 U/kg three times a day) or high (3 χ 106 U/kg three times a day) doses of IL-2 or saline intraperitoneally for 4 days. On days 4 and 10 post-C1300 NRB inoculation, mice were killed for assessment of natural killer cell and tumor specific cytotoxicity. Remaining animals were followed for tumor incidence, tumor growth, and duration of host survival. Interleukin-2 therapy in mice receiving dietary arginine compared with those receiving glycine resulted in significantly augmented natural killer cell cytotoxicity (day 4) and generation of specific tumoricidal mechanisms (day 10). The addition of dietary arginine to low-dose IL-2 therapy significantly diminished C1300 NRB engraftment (p < 0.05) and growth (p < 0.001) and prolonged the duration of host survival (p < 0.05) compared with the glycine treatment group. In vitro studies demonstrated that L-arginine is an essential substrate for optimal generation of LAK cells. Thus, supplemental dietary L-arginine enhances lymphocyte cytotoxic mechanisms and potentiates IL-2 immunotherapy.

Regional treatment of hepatic micrometastasis by adenovirus vector-mediated delivery of interleukin-2 and interleukin-12 cDNAs to the hepatic parenchyma.

We hypothesize that adenovirus (Ad) vector-mediated delivery of the human interleukin-2 (IL-2) cDNA (AdIL2) or the murine IL-12 cDNA heterodimer (AdIL12) would produce high concentrations of cytokines in the local hepatic milieu to induce host responses sufficient to inhibit the growth of experimental colon carcinoma-derived hepatic metastases. Ad vectors administered intravenously, which is a route known to deliver >90% of the vector to the hepatic parenchyma, achieved significant levels of each cytokine locally, with minimal levels in the sera. To examine the therapeutic effect, the AdIL2 and AdIL12 vectors were evaluated in a hepatic metastasis model that was established by injecting 3 × 104 cells from the poorly immunogenic syngeneic C26 colon carcinoma cell line into the right lobe of the livers of BALB/c mice. Animals received AdIL2, AdIL12, or control virus (108 plaque-forming units each) intravenously for 2 days after tumor implantation, and tumor growth was compared with naive controls. The AdNull control tumors measured 116 ± 25 mm2 at 2 weeks. The control virus showed no significant antitumor effect. In marked contrast, both AdIL2 and AdIL12 vectors that were delivered regionally had significant antitumor effects, with AdIL2-treated animals having an average tumor size of 16 ± 8 mm2; AdIL12-treated tumors measured 6 ± 6 mm2 (P < .01, both compared with control). Both the AdIL2 and AdIL12 vectors provided a significant survival advantage by log-rank analysis (P < .01), but only AdIL12 translated into an increase in mean survival from 27 (naive control) to 37 days. To evaluate whether these antitumor effects were T-cell-mediated, splenocytes from AdIL2-treated, AdIL12-treated, and naive control groups were stimulated in vitro with γ-irradiated C26 tumor cells for 5 days and tested for C26 tumor cell cytolysis by an in vitro cytotoxicity assay. Splenocytes from both AdIL2- and AdIL12-treated animals showed a dose-dependent, T-cell-mediated, specific cytolysis of CT26 cells. AdIL12 and to a lesser extent AdIL2 induced natural killer cell activity, as determined by a dose-dependent increase in lysis of the natural killer-specific target cell YAC-1. Overall, these data suggest that regional Ad-mediated delivery of IL-2 and IL-12 cDNAs may be useful for local tumor control and may warrant further investigation as a potentially useful adjuvant for the treatment of hepatic micrometastasis.

Nutritional Support of Patients with Cancer of the Gastrointestinal Tract

Malnutrition is extremely common in patients with malignant disease. Whereas the causes are multifactorial, the predominant factor is the imbalance between nutrient intake and host nutrient requirements. Furthermore, the evidence suggests that cachexia is related to abnormal changes in host intermediary metabolism induced by host-tumor interactions, and endogenous peptides such as TNF may be important mediators. The role of nutritional therapy in cancer patients remains to be defined. Clearly, patients with severe malnutrition benefit from nutritional intervention. However, the benefit of nutritional therapy in less severe cases of malnutrition as an adjuvant to oncologic therapy has yet to be established.

Comparison of acute and chronic protein-energy malnutrition on host antitumor immune mechanisms

Protein-calorie malnutrition (PCM) is prevalent in cancer patients. However, the effect of PCM on anti-tumor immunity is unclear and critically important in an era of improving results with adoptive immunotherapy. This study examined the effect of short- and long-term PCM on tumor-specific and natural immune effector mechanisms in a murine neuroblastoma (C1300 NRB) model. A/J mice received an isocaloric 2.5% or 24% casein diet for 3 or 8 weeks before inoculation with tumor. Three weeks later lymphocytes from tumor-bearing mice were harvested for determination of cytotoxic T lymphocyte (CTL) generation and natural killer (NK) cell cytotoxicity. Both 3 and 8 weeks of PCM significantly reduced mean total body weight by 25% (p less than 0.001) and 41% (p less than 0.001), respectively, compared with regularly nourished mice. Short-term PCM did not inhibit CTL or NK cytotoxicity, whereas long-term PCM significantly diminished CTL generation (p less than 0.001) but preserved NK cytotoxic function. These results indicate that CTL development against autologous tumor, in contrast to basal NK function, is dependent on host nutritional status. Mean tumor growth, determined by tumor-weight to carcass-weight ratio, was unchanged for both short- and long-term protein-energy deprived groups compared with results in regularly nourished mice. These findings suggest that NK function is the predominant effector mechanism inhibiting C1300 NRB growth and that NK tumoricidal capacity is preserved during PCM.