Remote regulation of type 2 immunity by intestinal parasites.

The intestinal tract is the target organ of most parasitic infections, including those by helminths and protozoa. These parasites elicit prototypical type 2 immune activation in the host's immune system with striking impact on the local tissue microenvironment. Despite local containment of these parasites within the intestinal tract, parasitic infections also mediate immune adaptation in peripheral organs. In this review, we summarize the current knowledge on how such gut-tissue axes influence important immune-mediated resistance and disease tolerance in the context of coinfections, and elaborate on the implications of parasite-regulated gut-lung and gut-brain axes on the development and severity of airway inflammation and central nervous system diseases.

The prostaglandin D2 receptor CRTH2 regulates accumulation of group 2 innate lymphoid cells in the inflamed lung.

Group 2 innate lymphoid cells (ILC2s) promote type 2 cytokine-dependent immunity, inflammation, and tissue repair. Although epithelial cell-derived cytokines regulate ILC2 effector functions, the pathways that control the in vivo migration of ILC2s into inflamed tissues remain poorly understood. Here, we provide the first demonstration that expression of the prostaglandin D2 (PGD2) receptor CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells) regulates the in vivo accumulation of ILC2s in the lung. Although a significant proportion of ILC2s isolated from healthy human peripheral blood expressed CRTH2, a smaller proportion of ILC2s isolated from nondiseased human lung expressed CRTH2, suggesting that dynamic regulation of CRTH2 expression might be associated with the migration of ILC2s into tissues. Consistent with this, murine ILC2s expressed CRTH2, migrated toward PGD2 in vitro, and accumulated in the lung in response to PGD2 in vivo. Furthermore, mice deficient in CRTH2 exhibited reduced ILC2 responses and inflammation in a murine model of helminth-induced pulmonary type 2 inflammation. Critically, adoptive transfer of CRTH2-sufficient ILC2s restored pulmonary inflammation in CRTH2-deficient mice. Together, these data identify a role for the PGD2-CRTH2 pathway in regulating the in vivo accumulation of ILC2s and the development of type 2 inflammation in the lung.

Selective ablation of the YxxM motif of IL-7Ralpha suppresses lymphomagenesis but maintains lymphocyte development.

Tumor progression is a multiple step process in which, in addition to oncogenic mutation, other supporting factors can contribute to transformation. The role these factors have in cancer is an open question. Using the Emicro-myc model of B-cell transformation, we evaluated the contribution of the cytokine interleukin-7 (IL-7) in supporting lymphomagenesis. We have previously shown that disruption of the Y449xxM motif of the IL-7 receptor alpha (IL-7Ralpha) in a knock-in mouse model (IL-7Ralpha(449F)) has minor effects on lymphocyte production, but interferes with the activation of survival effectors. To address the hypothesis that targeted signal ablation would selectively affect lymphocyte transformation, IL-7Ralpha(449F) mice were crossed with two lymphomagenesis models, transgenic (Tg) IL-7 and Emicro-myc mice. We found that the loss of IL-7Ralpha Y449 signaling prevented Tg IL-7-mediated T- and B-lymphocyte transformation and decreased the development of Emicro-myc-induced B-cell tumors. We showed that the IL-7Ralpha(449F) mutation prevented increased survival of Tg IL-7 CD8 T cells, and decreased viability of bone marrow progenitor B cells, as well as Emicro-myc-induced proliferation. This study shows that IL-7Ralpha Y449 is important for lymphocyte transformation, and that unlike deficiencies in pre-B cell receptor signaling, Myc overexpression cannot compensate for the loss of IL-7Ralpha signals in early B-cell development.

HLA-A/B haplotye frequencies among U.S. Hispanic and African-American populations.

HLA-A/B haplotype frequency tables were developed for U.S. Hispanic and African-American populations from data collected from paternity cases. Two Hispanic tables were developed; one was based on data from Hispanics in the northeast U.S. and Florida and designated the Caribbean table whilte all other Hispanics were included in a table designated the Mexican table. The total number of individuals whose haplotypes were included in the Caribbean, Mexican, African-American tables was 1635, 2230, and 3134, respectively. Statistical comparisons were made of haplotype frequencies among these tables and tables previously reported.

Transformation of C3H/10T1 2 cells and induction of EBV-early antigen in Raji cells by altertoxins I and III.

Moulds of the genus Alternaria are common contaminants of some food crops. Some isolates have been shown to produce mutagenic compounds called altertoxins. Altertoxin I (ATX-I) and altertoxin III (ATX-III) were examined for activity in the Raji cell Epstein-Barr virus early antigen (EBV-EA) induction system and in the C3H/10T1 2 murine fibroblast cell transformation system. Exposure of Raji cells to ATX-I or ATX-III activated EBV-EA expression by 8- and 9.5-fold, respectively. A single exposure of C3H/10T1 2 cultures to ATX-I or ATX-III resulted in significant increases in cell transformation, and the response to ATX-I was stronger. Both altertoxins enhanced the transformation of C3H/10T1 2 cells, and chronic exposure of non-initiated C3H/10T1 2 cells to ATX-I and ATX-III, starting 6 days after cells were plated, resulted in cell transformation in 8 59 and 12 37 dishes, respectively, compared with transformation in only 2 63 control dishes. Since activation of EBV-EA in Raji cells has been positively correlated with tumour promoters, these data together indicate that ATX-I and ATX-III are not just mutagens but have a potential role in cell transformation.

Effects of a strong and a weak carcinogen on murine alpha/beta interferon production in vivo.

A study was designed to determine whether oral doses of carcinogens would reduce an animal's ability to produce interferon. Female BCF1 mice were tested with various doses of benzo[alpha]pyrene (BP) or ethyl methanesulfonate (EMS) po (four to six mice per treatment) and challenged an hour later with the chemical interferon inducer tilorone. After 16-18 hr, mice were sacrificed and bled from the heart. Serum obtained from the blood was assayed for interferon. We found that mice treated with as little as 50 mg/kg BP or EMS had a statistically significant reduction in serum interferon titers compared with control-treated mice. Reductions in interferon titers were also noted at lower doses of the carcinogens, but due to the variability within the small sample size used, the reduction were not statistically significant. On a molar basis, BP was only two to three times more effective at reducing interferon titers than EMS. It was estimated from the data that slightly less than 10 mg/kg BP or 29 mg/kg EMS would be the doses corresponding to 50% reduction in control interferon titers. These doses are well below the reported mutations doses for these chemicals. The effect of carcinogens on in vivo interferon production reported here may be the most sensitive biologic system known for these chemicals.

Reduction in antiviral activity of human beta interferon by gallic acid.

Gallic acid (GA) is a common part of the human diet, both in the free form and as a metabolite of tannic acid and propyl gallate. Cell cultures were incubated with mixtures of either GA and beta interferon (IFN-beta) (formerly fibroblast IFN) or medium and IFN-beta. The cells were subsequently challenged with virus. The virus plaque yields were greater in cells incubated with IFN-beta and GA than in cells incubated with IFN-beta and medium, indicating that in the former mixture, IFN-beta had lost antiviral activity. The magnitude of the loss was dependent upon the GA concentration. IFN-alpha and IFN-gamma (formerly leukocyte IFN and immune IFN, respectively) were not similarly affected. The effect of GA on IFN-beta could be reversed with 2-mercaptoethanol, suggesting a possible sulfhydryl involvement. Extensive dialysis of IFN-beta-GA mixtures to remove the GA failed to reverse the reduction in antiviral activity. This suggests that a direct and irreversible interaction between IFN-beta and GA took place, reducing the activity of IFN-beta. The significance of this finding with regard to virus infections of the intestine is discussed.

Induction of an inhibitor of interferon action in a mouse lymphokine preparation.

An inhibitor of interferon action was identified in mouse lymphokine preparations. The inhibito was first detected in the supernatant fluid of mouse spleen cells at 72 h after stimulation by staphylococcal enterotoxin A. Inhibitor was not detected in supernatant fluids from unstimulated cultures. This inhibitor blocks the antiviral activity of both immune and fibroblast interferons. The inhibitor was purified 1,000-fold by two-step column chromatography. The partially purified inhibitor blocked the antiviral activity of up to 400 U of interferon. The immunosuppressive effect of interferon was also blocked by the inhibitor, suggesting that the inhibitor may modulate the immunoregulatory function of interferon.

Potentiation of interferon activity by mixed preparations of fibroblast and immune interferon.

Mixed preparations of fibroblast and immune interferons interacted with cells synergistically to cause the development of a much greater level of protection than expected on the basis of their separate activities. This increased level of protection was 5- to 20-fold greater than expected on the basis of a simple additive effect of the interferons. The potentiating factor copurified with both fibroblast interferon and immune interferon as they were partially purified. The potentiation was not an artifact of a more rapid development of immune interferon-induced antiviral resistance in the presence of fibroblast interferon. The results were consistent with the hypothesis that fibroblast and immune interferons mutually potentiate each other, thus supporting the supposition that they have different modes of action.

Large-scale production and partial purification of mouse immune interferon.

Large-scale production of high-titered (10(2.2) to 10(4) U/ml) immune interferon (type II) was carried out in roller cultures of mouse spleen cells by using the T-cell mitogen staphylococcal enterotoxin A. Precipitation of 90% of this interferon by 55 to 80% saturated ammonium sulfate resulted in a 20-fold concentration and a two- to sixfold purification. After application of this interferon to either bovine serum albumin (BSA)-Affi-Gel 10 or hydroxylapatite columns, 100% of the interferon activity was recovered. By BSA-Affi-Gel 10 chromatography, 7% of the recovered activity was not bound, 45% was eluted with pH gradient 5 to 7, and 48% was eluted with 1 M NaCl. The pH- and salt-eluted interferons from the BSA-Affi-Gel 10 column were purified 62- and 390-fold, respectively, when compared with the starting materials. Rechromatography of the pH- and salt-eluted interferon peaks from the BSA-Affi-Gel 10 column did not alter their elution patterns. Stepwise elution of interferon from the BSA-Affi-Gel 10 columns with buffers of various pH and salt contents also resulted in greater than 300-fold purification. Specific activities of up to 2 x 10(5) U of interferon per mg of protein were attained with either elution procedure from BSA-Affi-Gel 10 columns. By hydroxylapatite chromatography, 5% of the recovered activity was not bound, 20% was eluted with a salt gradient, and 75% was eluted with 30% glycerin. Purification was 107- and 16-fold, respectively, for the two fractions. Ultrogel AcA 34 chromatography of the interferon resulted in two peaks of activity, a major one with a molecular weight of approximately 40,000 and a minor peak of molecular weight 70,000 to 90,000. Thus, by different types of chromatography, immune interferon was found to be heterogeneous.