Human beta-defensin 2 (hBD-2) plays a role in the innate defence system at mucosal surfaces. Colonisation of Helicobacter pylori in the stomach is an important pathological factor in gastrointestinal ...illnesses, including gastritis, peptic ulcer, and gastric adenocarcinoma.
To evaluate the antibacterial role of hBD-2 against H pylori infection in the gastric mucosa.
Biopsied gastric mucosa specimens from H pylori positive (n=6) and H pylori negative (n=6) individuals were used. H pylori was determined by the presence of urease activity and microscopic examination.
The specimens were examined for hBD-2 expression by reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry, and in situ hybridisation. The antibacterial effect of hBD-2 against H pylori was evaluated by the number of colony forming units of H pylori after incubation with 0, 10(-9), 10(-8), 10(-7), 10(-6), or 10(-5) M of hBD-2 peptide.
All six H pylori positive specimens expressed a high level of hBD-2 mRNA while hBD-2 mRNA was not detected in the H pylori negative specimens by RT-PCR. Immunohistochemistry using anti-hBD-2 antiserum revealed that hBD-2 was expressed in the surface epithelium of H pylori infected specimens. In gastric specimens obtained after H pylori eradication, hBD-2 immunoreactivity had dramatically decreased. In situ hybridisation confirmed that hBD-2 transcripts were localised in the epithelium of H pylori infected gastric specimens. Incubation with hBD-2 reduced the growth rate of cultured H pylori in a dose dependent manner, and incubation with 10(-5) M hBD-2 completely inhibited the proliferation of H pylori.
H pylori infection induces hBD-2 expression in the human gastric epithelium. hBD-2 inhibited the growth of H pylori in vitro, suggesting that hBD-2 plays an antibacterial role in H pylori induced gastritis.
The ultrafast surface plasmon resonance nonlinearities and their connection with the conduction band electron dynamics are discussed in metal nanoparticles in the light of the results of high ...sensitivity femtosecond pump-probe experiments in silver nanoparticles embedded in a glass matrix. The optical response is interpreted in terms of frequency shift and broadening of the surface plasmon resonance and is related to the changes of the metal nanoparticle dielectric function induced by ultrafast perturbation of the electron distribution. Alteration of the interband absorption is found to be responsible for the observed red shift and very short time delay broadening of the surface plasmon resonance, in agreement with numerical simulations and with measurements in silver films. On a longer time scale, a new nonlinear mechanism due to increase of the electron scattering off the surfaces is demonstrated. This mechanism, specific to confined system, plays an important role in the ultrafast nonlinear optical response of small nanoparticles.
A limited number of therapeutic strategies are currently available for patients with inflammatory bowel disease (IBD). In particular, the maintenance therapy after remission in Crohn's disease (CD) ...is not satisfactory and new approaches are needed. Interleukin-10 gene-deficient (IL-10⁻/⁻) mice, a well-characterized experimental model of CD, develop severe chronic colitis due to an aberrant Th1 immune response. Everolimus, an inhibitor of the mammalian target of rapamycin (mTOR), a new immunosuppressive reagent, has been used successfully in animal models for heart, liver, lung and kidney transplantation. In the present study, we examined the efficacy of everolimus in the treatment of chronic colitis in an IL-10⁻/⁻ mouse model. Everolimus was administered orally for a period of 4 weeks to IL-10⁻/⁻ mice with clinical signs of colitis. The gross and histological appearances of the colon and the numbers, phenotype and cytokine production of lymphocytes were compared with these characteristics in a control group. The 4-week administration of everolimus resulted in a significant decrease in the severity of colitis, together with a significant reduction in the number of CD4⁺ T cells in the colonic lamina propria as well as IFN-γ production in colonic lymphocytes. Everolimus treatment of established colitis in IL-10⁻/⁻ mice ameliorated the colitis, probably as a result of decreasing the number of CD4⁺ T cells in the colonic mucosa and an associated reduction in IFN-γ production.
PDF
