Potential role of bacterial lipopolysaccharides in the development of autoimmune gastritis induced by neonatal thymectomy

The role of LPS in the development of autoimmune gastritis (AIG) in BALB/c mice thymectomized on day 3 after birth (d3-Tx) was investigated in LPS-non -responder BALB/lps(d) mice. The symptoms were classified into three types: (i) hypertrophic stomach (HS) and lymphocyte infiltration (LI)-double nega tive; (ii) MS-negative and LI-positive; and (iii) HS- and LI-double positiv e. The double positive type-3 was termed AIG. Following d3-Tx, LPS-responde r BALB/c (Lps(n)) mice showed the following incidence: type-1 (14%), type-2 (14%) and type-3 (72%). In contrast, the incidence in BALB/lps(d) mice was 67%, 22% and 11%, respectively. Thus the frequency of AIC development in B ALB/lps(d) mice was much lower than in BALB/c mice. A single administration of LPS on day 2 post-d3-Tx induced severe AIG incidence in all d3-Tx BALB/ c mice but not in d3-Tx BALB/lps(d) mice, suggesting that LPS influences th e progression of AIG development. Formation of auto-antibodies against the proton pump (H+/K+-ATPase) seemed to be related to AIG incidence in d3-Tx B ALB/c mice. In d3-Tx BALB/lps(d) mice, however, higher levels of auto-antib odies were detected in the type-2 mice, whereas AIG incidence was much lowe r than that in d3-Tx BALB/c mice. Thus, formation of auto-antibodies agains t the proton pump in d3-Tx BALB/lps(d) mice does not appear to correlate wi th AIG pathogenesis.