Effect of Th1 cytokines on acid secretion in pharmacologically characterised mouse gastric glands

Abstract

Background and aims: Acid secretion plays an important role in the ecology of Helicobacter species and acid secretory status heralds patterns of gastritis. The presence of inflammatory cells and their products, in close proximity to parietal cells, questions the extent of the effect of cytokines on acid secretion.

Methods: We adopted and extensively characterised the mouse gastric gland preparation and its secretory capacity, which was measured using (14)C-aminopyrine accumulation. Subsequently, we tested the secretory properties of a wide range of species specific cytokines, including those associated with Th1 and Th2 immune responses.

Results: (14)C-aminopyrine accumulation in mouse gastric glands was shown to be a very sensitive "in vitro" method of testing classical secretagogues and antisecretory compounds, and provided pharmacological data on acid secretion in the mouse. Only two mouse cytokines, interleukin 2 and interferon gamma, had a direct effect on acid secretion causing dose dependent inhibition.

Conclusions: Both cytokines belong to the Th1 type immune response and consequently their inhibitory effect may play a role in the hyposecretion seen with H pylori infection and colonisation throughout the corpus of the stomach that potentially can lead to gastric atrophy and subsequently, in some cases, cancer.

Figure 1

Photograph showing preparation of mouse gastric glands. Arrows indicate luminal canal inside the gland surrounded by bulging parietal cells (400× magnification).

Figure 2

(A) Effect of incubation time on basal and secretagogue stimulated acid secretion, as measured by [¹⁴C]aminopyrine accumulation in mouse gastric glands (n = 3). Hist, histamine; Carb, carbachol. (B) Effect of antagonists on maximal acid output (100%) induced by 0.1 M of histamine (n = 4–6). (C) Effect of histamine receptor type specific agonists on basal acid secretion (n = 4–6). PEA, piridylethylamine; R-α-MH, R-α-methylhistamine. (D) Effect of muscarinic receptor antagonists on 0.01 M carbachol stimulated acid secretion (n = 3). p-FHHSDiF, fluorohexahydrosiladifenidol.

Figure 3

Effect of various secretagogues on acid secretion in the mouse gastric gland incubated for 60 minutes at 37°C. The dose-response was constructed for each secretagogue and this figure shows concentrations at which acid secretion was the highest/maximal. Maximal effect of secretagogues on acid secretion is expressed in relation to maximal histamine stimulation (100%) (n = 4–7). IBMX, 3-isobutyl-l-methylxantine; db-cAMP, adenosine cyclic monophosphate.

Figure 4

Inhibitory effect of various antisecretory drugs and agents on 0.1 mM histamine stimulated acid secretion (n = 4–9). PGE₂, prostaglandin E₂.

Figure 5

Inhibitory effect of the Th1 cytokines interferon γ (IFN-γ) and interleukin 2 (IL-2) on 0.1 mM histamine stimulated acid secretion measured by [¹⁴C]aminopyrine accumulation in mouse gastric glands (n = 4−5).

Figure 6

Inhibitory effect of Th1 cytokines interferon γ (IFN-γ) and interleukin 2 (IL-2) on 0.01 mM carbachol stimulated acid secretion measured by [¹⁴C]aminopyrine accumulation in mouse gastric glands (n = 4−5).

Figure 7

Effect of coincubation (coinc.) and preincubation (preinc.) of mouse gastric glands with 3×10⁻⁹ M interferon γ (IFN-γ) on histamine (A) and carbachol (B) dose-response curves, as measured by [¹⁴C]aminopyrine accumulation (n = 3–4). Preincubation for 60 additional minutes with IFN-γ was done in the absence of secretagogues and aminopyrine.

Figure 8

Reversal of the antisecretory effect of mouse interferon-γ (IFN-γ) in mouse gastric glands by rat antimouse IFN-γ monoclonal antibody (AB, 1:20 dilution of monoclonal rat antimouse IFN-γ, IgG1, or 25 μg). As non-specific/isotype control antibody, 25 μg of purified rat myeloma, IgG1 was used.