NKX6.3 protects against gastric mucosal atrophy by downregulating β-amyloid production

Figure 3 Amyloid β oligomerization is strongly associated with gastric mucosal atrophy. A: In Western blot analysis, amyloid β (Aβ) oligomers were expressed only in gastric mucosae with atrophy. Expression of apolipoprotein E (ApoE), β-secretase 1 (Bace1), and cleaved form of caspase-3 were increased in atrophic gastric mucosae with reduced NKX6.3 expression. B and C: Expression levels of ApoE and Bace1 mRNAs were significantly higher in gastric mucosae with atrophy (B), showing inverse correlations with NKX6.3 expression (P < 0.0001, C). Shown are the means ± SEM from three experiments. Superscript letter represents significant difference (^aP < 0.0001, ^bP < 0.0001 and ^cP < 0.0001). D: In Aβ42 enzyme-linked immunosorbent assay, concentrations of aggregated Aβ were significantly increased in gastric mucosae with (W/) atrophy (1.20 ± 0.60 μg/mL) compared to without (W/O) atrophy (0.09 ± 0.09 μg/mL). Shown are the means ± SEM from three experiments. Superscript letter represents significant difference (^dP < 0.0001). E: Western blot analysis showing decreased expression of NKX6.3 and increased expression of ApoE, Aβ oligomer, Bace1, and cleaved caspase-3 proteins in CagA transfected HFE-145 cells. In addition, CagA significantly increased concentrations of aggregated Aβ in both cell lysate and culture media. Shown are the means ± SEM from three experiments. Superscript letter represents significant difference (^eP < 0.005 and ^fP < 0.0001). F: Knock-down of Aβ inhibited CagA-induced floating cells populations. Shown are the means ± SEM from three experiments. Superscript letter represents significant difference (^gP < 0.005 and ^hP < 0.0001). G: Immunofluorescence analysis showing expression of Aβ oligomer and Bace1 only in gastric mucosae with atrophy, but not in gastric mucosa without atrophy. Right panel is a higher magnification of the Aβ oligomer and Bace1 in the inlet in gastric mucosae with atrophy. ApoE: Apolipoprotein E; Aβ: Amyloid β; Bace1: β-secretase 1; W/: With atrophy; W/O: Without atrophy.