Effect of CTH on H. pylori survival. (a) Macrophages were treated with LY294002 (LY) for 30 min and infected or not with H. pylori for 24 h. Cells were washed, and fresh medium containing antibiotics and AOAA or PAG was added. After 24 h, the cystathionine concentration was determined in cells (top) and supernatants (bottom). *, P < 0.05; **, P < 0.01; ****, P < 0.0001 (versus uninfected cells); §§, P < 0.01; §§§, P < 0.001; §§§§, P < 0.0001 (versus infected cells without an inhibitor) (n = 5 to 7). (b) Macrophages were transfected with LmnA or Cth siRNA and infected or not with H. pylori for 24 h. Cells were washed, and fresh medium containing antibiotics was added. The cystathionine concentration was measured in cells (top) and supernatants (bottom) after 24 h. *, P < 0.05; **, P < 0.01; ****, P < 0.0001 (versus uninfected cells); §, P < 0.05; §§§§, P < 0.0001 (versus cells transfected with LmnA siRNA and infected with H. pylori) (n = 3). (c) Macrophages were infected or not with H. pylori PMSS1, in the presence or absence of 100 μM methionine (Met). Bacteria were also cultured in the same medium without cells. After 24 h, the cystathionine concentration was determined in macrophages or bacteria. ****, P < 0.0001 (versus uninfected cells); §§§§, P < 0.0001 (versus infected cells) (n = 3). (d) Macrophages were transfected with LmnA or Cth siRNA and then infected with H. pylori for 24 h, with or without cystathionine (50 to 1,000 ng/ml). The number of CFU in macrophages was determined by a gentamicin assay. ****, P < 0.0001 (versus cells transfected with LmnA siRNA); §§§, P < 0.001; §§§§, P < 0.0001 (versus cells transfected with Cth siRNA without cystathionine treatment) (n = 3). (e) Macrophages were transfected with LmnA or Cth siRNA and then infected or not with H. pylori (Hp) for 24 h. Cells were washed, and fresh medium was added. After 24 h, supernatants were collected, filtered, and used to grow H. pylori. *, P < 0.05; **, P < 0.01 (versus all other conditions) (n = 5). (f) Macrophages were transfected with LmnA or Cth siRNA and then infected with C. jejuni with or without 100 ng/ml cystathionine for 24 h. The number of CFU in macrophages was determined by a gentamicin assay. *, P < 0.05 (versus cells transfected with LmnA siRNA); §, P < 0.05 (versus cells transfected with Cth siRNA without cystathionine) (data are from 4 experiments).