[Effect of intranasal IL-12 gene therapy on the mice eosinophils and IL-5 in the murine model of allergic rhinitis].

OBJECTIVE: To evaluate the effect of intranasal liposome-mediated IL-12 gene therapy on the eosinophils and IL-5 in the murine model of allergic rhinitis. METHODS: Thirty-six BALB/C mice were randomly divided into allergic rhinitis (AR) group, gene therapy group and control group. Allergic rhinitis group were sensitized and stimulated by ovalbumin (OVA), and gene therapy group were administered with liposome-mediated pGEG. mIL-12 transnasally before stimulated. The eosinophils in bone marrow were counted by Wright's staining, and the eosinophils in nasal mucosa were counted by HE staining. The eosinophils of peripheral blood were detected by flow cytometry. The expression of IL-5 in bone marrow and nasal mucosa was examined by immunohistochemistry. The IL-5 in serum was detected by ELISA. RESULTS: Among the three groups, the difference of all data was statistically significant (P<0.01). Multiple Comparison showed that the ratio of eosinophils to white cells and the mount of IL-5 positive cells in nasal mucosa and bone marrow of gene therapy group was significantly lower than that of AR group (P<0.05). The ratio of eosinophils to granulocyte (0.124 +/- 0.031) and the expression level of IL-5 [(29.51 +/- 6.68) pg/ml] in peripheral blood [ 0.184 +/- 0.079 and (56.58 +/- 16.80) pg/ml] were significantly lower in gene therapy group than in AR group (P<0.05). CONCLUSIONS: Transnasal administration of liposome- mediated pGEG. mIL-12 could depress the expression of IL-5 in bone marrow, peripheral blood, and nasal mucosa, to influence the proliferation and differentiation of eosinophils and decrease the delivery and transference of eosinophils to peripheral blood and nasal mucosa. It may be a new treatment for respiratory tract allergic inflammation.

Calcium is a cofactor of polymerization but inhibits pyrophosphorolysis by the Sulfolobus solfataricus DNA polymerase Dpo4.

Y-Family DNA polymerase IV (Dpo4) from Sulfolobus solfataricus serves as a model system for eukaryotic translesion polymerases, and three-dimensional structures of its complexes with native and adducted DNA have been analyzed in considerable detail. Dpo4 lacks a proofreading exonuclease activity common in replicative polymerases but uses pyrophosphorolysis to reduce the likelihood of incorporation of an incorrect base. Mg(2+) is a cofactor for both the polymerase and pyrophosphorolysis activities. Despite the fact that all crystal structures of Dpo4 have been obtained in the presence of Ca(2+), the consequences of replacing Mg(2+) with Ca(2+) for Dpo4 activity have not been investigated to date. We show here that Ca(2+) (but not Ba(2+), Co(2+), Cu(2+), Ni(2+), or Zn(2+)) is a cofactor for Dpo4-catalyzed polymerization with both native and 8-oxoG-containing DNA templates. Both dNTP and ddNTP are substrates of the polymerase in the presence of either Mg(2+) or Ca(2+). Conversely, no pyrophosphorolysis occurs in the presence of Ca(2+), although the positions of the two catalytic metal ions at the active site appear to be very similar in mixed Mg(2+)/Ca(2+)- and Ca(2+)-form Dpo4 crystals.

Kinetics of nucleotide incorporation opposite DNA bulky guanine N2 adducts by processive bacteriophage T7 DNA polymerase (exonuclease-) and HIV-1 reverse transcriptase.

Six oligonucleotides with carcinogen derivatives bound at the N2 atom of deoxyguanosine were prepared, including adducts derived from butadiene, acrolein, crotonaldehyde, and styrene, and examined for effects on the replicative enzymes bacteriophage DNA polymerase T7- (T7-) and HIV-1 reverse transcriptase for comparison with previous work on smaller DNA adducts. All of these adducts strongly blocked dCTP incorporation opposite the adducts. dATP was preferentially incorporated opposite the acrolein and crotonaldehyde adducts, and dTTP incorporation was preferred at the butadiene- and styrene-derived adducts. Steady-state kinetic analysis indicated that the reduced catalytic efficiency with adducted DNA involved both an increased Km and attenuated kcat. Fluorescence estimates of Kd and pre-steady-state kinetic measurements of koff showed no significantly decreased affinity of T7- with the adducted oligonucleotides or the dNTP. Pre-steady-state kinetics showed no burst phase kinetics for dNTP incorporation with any of the modified oligonucleotides. These results indicate that phosphodiester bond formation or a conformational change of the enzyme.DNA complex is rate-limiting instead of the step involving release of the oligonucleotide. Thio elemental effects for dNTP incorporation were generally relatively small but variable, indicating that the presence of adducts may sometimes make phosphodiester bond formation rate-limiting but not always.