Is There a Role for the Enteral Administration of Serum-Derived Immunoglobulins in Human Gastrointestinal Disease and Pediatric Critical Care Nutrition?

Twenty years ago, there was profound, international interest in developing oral human, bovine, or chicken egg-derived immunoglobulin (Ig) for the prevention and nutritional treatment of childhood malnutrition and gastrointestinal disease, including acute diarrhea and necrotizing enterocolitis. Although such Ig products were shown to be effective, with both nutritional and antidiarrheal benefits, interest waned because of their cost and because of the perceived risk of bovine serum encephalitis (BSE). BSE is no longer considered a barrier to use of oral Ig, because the WHO has declared the United States to be BSE-free since the early 2000s. Low-cost bovine-derived products with high Ig content have been developed and are regulated as medical foods. These new products, called serum bovine Igs (SBIs), facilitate the management of chronic or severe gastrointestinal disturbances in both children and adults and are regulated by the US Food and Drug Administration. Well-established applications for use of SBIs include human immunodeficiency virus (HIV)-associated enteropathy and diarrhea-predominant irritable bowel syndrome. However, SBIs and other similar products could potentially become important components of the treatment regimen for other conditions, such as inflammatory bowel disease, by aiding in disease control without immunosuppressive side effects. In addition, SBIs may be helpful in conditions associated with the depletion of circulating and luminal Igs and could potentially play an important role in critical care nutrition. The rationale for their use is to facilitate intraluminal microbial antibody coating, an essential process in immune recognition in the gut which is disturbed in these conditions, thereby leading to intestinal inflammation. Thus, oral Ig may emerge as an important "add-on" therapy for a variety of gastrointestinal and nutritional problems during the next decade.

Hypoallergenic formula with Lactobacillus rhamnosus GG for babies with colic: A pilot study of recruitment, retention, and fecal biomarkers

AIM: To investigate recruitment, retention, and estimates for effects of formula supplementation with Lactobacillus rhamnosus GG (LGG) on inflammatory biomarkers and fecal microbial community in infants with colic.

METHODS: A prospective, double-blind, placebo-controlled trial was conducted in otherwise healthy infants with colic. We screened 74 infants and randomized and analyzed results in 20 infants [9 receiving LGG (LGG+) and 11 not receiving LGG (LGG-)]. LGG was incorporated in the formula (Nutramigen^®) (minimum of 3 × 10⁷ CFU/d) in the LGG+ group. Fecal microbiota and inflammatory biomarkers, including fecal calprotectin (FC), plasma cytokines, circulating regulatory T cells (Tregs), and crying + fussing time were analyzed to determine optimal time points and effect sizes for a larger trial.

RESULTS: Recruitment in this population was slow, with about 66% of eligible infants willing to enroll; subject retention was better (75%). These rates were influenced by parents’ reluctance to volunteer their infant for a clinical trial and by their tendency to change formulas. The maximal difference of crying + fussing time was observed at day 14, comparing the 2 groups, with a mean difference of -91 (95%CI: -76, 259) min (P = NS). FC showed no significant difference, but the optimal time to determine a potential effect was at day 90 [with a mean difference of 121 (95%CI: -48, 291) μg/g stool], observing a lower level of FC in the LGG+ group. The fecal microbial communities were chaotic, as determined by Shannon’s diversity index and not apparently influenced by the probiotic. No significant change was observed in plasma inflammatory cytokines or Tregs, comparing LGG+ to LGG- groups.

CONCLUSION: Designing future colic trials involving a probiotic-supplemented formula for infants in the United States will require consideration for difficult enrollment. Infants with colic have major variations in feal microbiota and calprotectin, both of which improve with time, with optimal time points for measurement at days 14 and 90 after treatment.

Activation of PPARgamma enhances myocardial glucose oxidation and improves contractile function in isolated working hearts of ZDF rats

It is suggested that insulin resistance and metabolic maladaptation of the heart are causes of contractile dysfunction. We tested the hypothesis whether systemic PPARgamma activation, by changing the metabolic profile in a model of insulin resistance and type 2 diabetes (the ZDF rat) in vivo, improves contractile function of the heart in vitro. Male Zucker diabetic fatty (ZDF) and Zucker lean (ZL) rats, at 53-56 days of age, were treated with either GI-262570 (a nonthiazolidinedione PPARgamma agonist; A) or vehicle (V) for 1 wk. Agonist treatment resulted in correction of hyperglycemia and dyslipidemia, as well as in reduced hyperinsulinemia. The accumulation of triacylglycerols in the myocardium, characteristic of the ZDF rat, disappeared with treatment. Cardiac power and rates of glucose oxidation in the isolated working heart were significantly reduced in ZDF-V rats, but both parameters increased to nondiabetic levels with agonist treatment. In ZDF-V hearts, transcript levels of PPARalpha-regulated genes and of myosin heavy chain-beta were upregulated, whereas GLUT4 was downregulated compared with ZL. Agonist treatment of ZDF rats reduced PPARalpha-regulated genes and increased transcripts of GLUT4 and GLUT1. In conclusion, by changing the metabolic profile, reducing myocardial lipid accumulation, and promoting the downregulation of PPARalpha-regulated genes, PPARgamma activation leads to an increased capacity of the myocardium to oxidize glucose and to a tighter coupling of oxidative metabolism and contraction in the setting of insulin resistance and type 2 diabetes.

Tissue-specific microvascular endothelial cell lines from H-2K(b)-tsA58 mice for studies of angiogenesis and metastasis

Microvascular endothelial cells play a critical role in tumor progression and metastasis by forming capillary networks that encourage tumor growth and by promoting the attachment of circulating tumor cells to the vascular wall of distant tissues. Efforts to study the molecular mechanisms that mediate these complex processes in different anatomical compartments have been impeded by difficulties in the isolation and propagation of endothelial cells from different organs. To overcome these limitations, we used two-color flow cytometry to identify and select microvascular endothelial cells from primary cultures obtained from different organs of mice whose tissues harbor a temperature-sensitive SV40 large T antigen (H-2K(b)-tsA58 mice; ImmortoMice). The selection strategy targeted cell populations expressing the inducible endothelial cell adhesion molecules, E-selectin and VCAM-1, and proved successful in generating microvascular endothelial cell lines from a number of different organs. When cultured under permissive temperatures (33 degrees C), individual cell lines displayed doubling times consistent with endothelial cells possessing an angiogenic phenotype. The transfer of endothelial cells to nonpermissive temperatures (37 degrees C) resulted in cell differentiation and the induction of a quiescent state. Established cell lines exhibited several inherent endothelial properties, including the expression of constitutive and inducible levels of endothelial cell adhesion molecules E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1, internalization of acetylated low-density lipoprotein, and formation of loop structures on Matrigel surfaces. The immortalized endothelial cell lines established from H-2K(b)-tsA58 mice provide, for the first time, a cell culture system to examine factors regulating angiogenesis and tumor cell arrest in different organ systems.

Type-1 transforming growth factor-beta differentially modulates tumoricidal activity of murine peritoneal macrophages against metastatic variants of the B16 murine melanoma

Transforming growth factor-beta 1 (TGF-beta 1) renders mouse peritoneal macrophages tumoricidal against metastatic variants of the B16 mouse melanoma in vitro. Both direct cytotoxicity and indirect cytotoxicity were observed. A subthreshold concentration (10 U/ml) of recombinant murine interferon-gamma (rMuIFN-gamma) enhanced the direct tumoricidal activity of TGF-beta 1-activated macrophages from 29% to 88% but did not change their indirect tumoricidal profile. Data obtained from macrophages preincubated with either TGF-beta 1 or rMuIFN-gamma showed that TGF-b1 can initiate tumoricidal activity better than rMuIFN-gamma. These effects were plasma-membrane mediated because targeting macrophages with liposomal TGF-beta 1 was ineffective. The order of tumoricidal susceptibility of the B16 melanoma lines to activated macrophages was B16F1 > B16F10 > B16BL6, in inverse order of metastatic potential.

Contributions of stromal metalloproteinase-9 to angiogenesis and growth of human ovarian carcinoma in mice

BACKGROUND

The expression level of several matrix metalloproteinases (MMPs), including MMP-2 and MMP-9, in ovarian cancer cells is directly associated with their invasive and metastatic potentials. MMP-9 is also expressed in stromal cells adjacent to the tumor. To investigate the contribution of MMP-9 expression in stromal cells to ovarian tumor growth, we examined angiogenesis and progressive growth of human ovarian cancer cells implanted into mice with and without the MMP-9 gene.

METHODS

Human ovarian cancer cells SKOV3.ip1 and HEY-A8 were implanted into the peritoneal cavities of nude mice that lacked the gene for MMP-9 (MMP-9(-/-)) or were wild type for MMP-9 (MMP-9(+/+)) (10 mice of each genotype per cell line). Tumor incidence, tumor size, and volume of ascites fluid were recorded for each mouse at 30 and 45 days after HEY-A8 and SKOV3.ip1 cell injections, respectively. Blood vessel density and macrophage infiltration into the lesions were analyzed in excised tumors by immunohistochemistry and double immunofluorescence. Tumor growth was also studied in MMP-9(-/-) nude mice that had been reconstituted with spleen cells collected from either MMP-9(+/+) or MMP-9(-/-) nude mice. All statistical tests were two-sided.

RESULTS

HEY-A8 cells expressed high levels of MMP-9, and SKOV3.ip1 cells expressed low levels. Nevertheless, tumor incidence and growth were statistically significantly lower in MMP-9(-/-) mice than in MMP-9(+/+) mice injected with cells from either line (for tumor size, P =.006 and.042 for HEY-A8 and SKOV3.ip1 cells, respectively). Compared with MMP-9(+/+) mice injected with human ovarian cancer cells, MMP-9(-/-) mice injected with human ovarian cancer cells displayed decreased microvessel density and decreased macrophage infiltration into the lesions. Compared with MMP-9(-/-) mice that received spleen cells (a rich source of macrophages) from MMP-9(-/-) mice, those that received spleen cells from MMP-9(+/+) mice before cancer cell injections displayed increased angiogenesis and tumorigenicity of the cancer cells. The growing tumors contained MMP-9-expressing macrophages.

CONCLUSION

Host-derived MMP-9 expression, most likely in tumor-infiltrating macrophages, appears to play a critical role in angiogenesis and progressive growth of human ovarian tumors in mice.

Targeted therapy against human lung cancer in nude mice by high-affinity recombinant antimesothelin single-chain Fv immunotoxin

Several tumors, including mesothelioma and ovarian cancer, can overexpress mesothelin, a glycosylphosphatidylinositol-linked differentiation glycoprotein. The membrane-bound type of mesothelin is found in the blood of cancer patients at a very low level, which makes mesothelin a good candidate for targeted therapy of certain cancers. An antimesothelin disulfide-linked Fv (SS1 Fv) was fused to a truncated mutant of Pseudomonas exotoxin A to produce the recombinant immunotoxin SS1(dsFv)-PE38, which has a high binding affinity to mesothelin (Kd = 0.7 nM). Our studies in vitro showed that SS1(dsFv)-PE38 is significantly more cytotoxic to the high-mesothelin-producing NCI-H226 human non-small cell lung cancer cells than to human lung adenocarcinoma PC14PE6 cells, which do not express mesothelin. When administered at a nontoxic dose of 500 microg/kg on days 7, 9, and 11 to nude mice injected i.v. with the two human lung cancer cell lines, SS1(dsFv)-PE38 selectively inhibited experimental lung metastases produced by the mesothelin-producing NCI-H226 cells. Our data indicate that mesothelin-producing squamous cell carcinoma of the lung may be a good target for this immunotoxin.

Stat1 negatively regulates angiogenesis, tumorigenicity and metastasis of tumor cells

Stat1 is deficient or inactive in many types of human tumors whereas some tumors have activated Stat1. Whether Stat1 affects tumor growth and metastasis is unclear. In the present study, we used Stat1 knockout tumor cells to determine (1) whether Stat1 can regulate angiogenesis, growth, and metastasis of tumor cells; and (2) whether Stat1 is required for the inhibitory effect of IFN-beta on the expression of angiogenic factor bFGF. Highly tumorigenic and metastatic RAD-105 tumor cells derived from a fibrosarcoma of a Stat1 knockout mouse were reconstituted with a Stat1 expression vector. The reconstitution of Stat1 suppressed the tumorigenicity and metastasis of RAD-105 cells in nude mice which correlated with a decreased microvessel density and decreased expression of proangiogenic molecules bFGF, MMP-2, and MMP-9 in vivo. Moreover, noncytotoxic concentrations of IFN-beta significantly inhibited the in vitro expression of bFGF in the Stat1-reconstituted cells but not in the Stat1-deficient cells, which was consistent with decreased bFGF expression of Stat1-reconstituted tumors in vivo. Therefore, Stat1 is essential for IFN-mediated inhibition of bFGF production, suggesting that tumor-intrinsic Stat1 is an important mediator for antiangiogenic signals, such as IFN. Collectively, these data demonstrate that Stat1 expressed by tumor cells is a negative regulator of tumor angiogenesis and, hence, tumor growth and metastasis.