Glucocorticoid receptors are downregulated in hepatic T lymphocytes in rats with experimental cholangitis - PubMed (original) (raw)

Glucocorticoid receptors are downregulated in hepatic T lymphocytes in rats with experimental cholangitis

K Tjandra et al. Gut. 2003 Sep.

Abstract

Background: and aims: Primary sclerosing cholangitis is a Th1 cytokine driven disease with a poor clinical responsiveness to glucocorticoid therapy. We have previously documented elevated circulating glucocorticoid levels in cholestatic rats and in addition have noted increased hepatic expression of the Th1 cytokine interferon gamma (IFN-gamma) in a rat model of cholangitis. Therefore, we examined the relationship between circulating glucocorticoid levels, hepatic IFN-gamma expression, and hepatic T cell glucocorticoid receptor (GR) expression in a rat model of cholangitis to provide insight into the possible mechanism underlying hepatic T cell glucocorticoid resistance in cholangitic diseases.

Methods: Cholangitis was induced in male Sprague-Dawley rats by oral administration of low dose alpha-naphthylisothiocyanate (ANIT). On day 14, ANIT fed and control rats were sacrificed, serum collected, and hepatic, splenic, and peripheral blood T lymphocytes isolated for GR expression, as determined by reverse transcription-polymerase chain reaction and western blotting.

Results: Circulating glucocorticoid levels were markedly elevated in ANIT fed rats. Hepatic T lymphocyte GR mRNA and protein levels were significantly reduced in ANIT treated rats compared with controls. In contrast, GR mRNA and protein expression in splenic and circulating T lymphocytes was similar in both groups. Furthermore, reduced hepatic T cell GR expression in ANIT fed rats was associated with reduced hepatic CD4(+) T cell sensitivity to dexamethasone inhibitory effects (that is, inhibition of interleukin 2 receptor expression).

Conclusion: We conclude that hepatic T lymphocyte resistance to elevated endogenous glucocorticoid levels in rats with experimental cholangitis appears, in part, to be mediated by decreased GR expression.

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Figures

Figure 1

Serum corticosterone and dehydroepiandrosterone (DHEA) levels in control and α-naphthylisothiocyanate (ANIT) treated rats. Data are mean (SEM) of at least four animals per group. (A) Corticosterone levels; (B) DHEA levels; and (C) serum corticosterone/DHEA ratio. *p<0.05 and ***p<0.001 versus controls.

Figure 2

(A) Circulating corticosterone levels in control animals and rats treated with α-naphthylisothiocyanate (ANIT) for 4, 7, and 14 days. Data are mean (SEM) of at least four animals per group. ***p<0.001 versus controls; ††p<0.01 versus day 4 and 7. (B) Morning and evening plasma corticosterone levels of control and ANIT fed rats for 14 days. Data are mean (SEM) of six animals per control group, and at least 13 rats per ANIT group. **p<0.01, ***p<0.001 versus control AM levels.

Figure 3

Hepatic cytokine protein levels in control and α-naphthylisothiocyanate (ANIT) treated rats. Data are mean (SEM) of at least four animals per group. (A) Th1 cytokine (interferon γ (IFN-γ)) levels; (B) Th2 cytokine (interleukin 4 (IL-4)) levels; and (C) hepatic Th1/Th2 cytokine ratio. *p<0.05 and **p<0.01 versus controls.

Figure 4

Glucocorticoid receptor (GR) expression in hepatic T lymphocytes isolated from control animals and rats treated with α-naphthylisothiocyanate (ANIT) for 14 days. Hepatic T lymphocyte GR mRNA levels were determined by reverse transcription-polymerase chain reaction (top panel; n=3–5) and protein expression by western blotting (lower panel; n=4). *p<0.05 and ***p<0.001 versus controls. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.

Figure 5

Splenic T lymphocyte glucocorticoid receptor (GR) expression in control and rats receiving α-naphthylisothiocyanate (ANIT) for 14 days. Splenic T lymphocyte GR mRNA levels are shown in the top panel (n=9) and protein expression in the lower panel (n=4). Similar splenic T lymphocyte GR mRNA and protein levels were observed between the control rats and those receiving ANIT for 14 days. GAPDH, glyceraldehyde-3 -phosphate dehydrogenase.

Figure 6

Peripheral blood T lymphocyte glucocorticoid receptor (GR) expression in control and rats receiving α-naphthylisothiocyanate (ANIT) for 14 days. Circulating T lymphocyte GR mRNA levels are shown in the top panel (n=7–8) and protein expression in the lower panel (n=4). Similar GR mRNA and protein levels in peripheral blood T lymphocytes were observed between the control rats and those receiving ANIT for 14 days.

Figure 7

A representative dot plot of surface expression of interleukin 2 receptors (IL-2R) on CD4+ liver derived lymphocytes of control rats and rats treated with α-naphthyliso-thiocyanate (ANIT) for 14 days. Freshly isolated hepatic lymphocytes were stimulated with concanavalin A (Con A) in the presence or absence of 10−7M dexamethasone (Dex). Similar results were obtained in two additional experiments.

References

1. Wiesner RH, Grambsch PM, Dickson ER_, et al._ Primary sclerosing cholangitis: natural history, prognostic factors and survival analysis. Hepatology 1989;10:430–6. - PubMed
1. Farrant JM, Hayllar KM, Wilkinson ML_, et al._ Natural history and prognostic variables in primary sclerosing cholangitis. Gastroenterology 1991;100:1710–17. - PubMed
1. Porayko MK, LaRusso NF, Wiesner RH. Primary sclerosing cholangitis: a progressive disease? Semin Liver Dis 1991;11:18–25. - PubMed
1. Berg PA, Klein R, Rocken M. Cytokines in primary biliary cirrhosis. Semin Liver Dis 1997;17:115–23. - PubMed
1. Tjandra K, Sharkey KA, Swain MG. Progressive development of a Th1-type hepatic cytokine profile in rats with experimental cholangitis. Hepatology 2000;31:280–90. - PubMed

Glucocorticoid receptors are downregulated in hepatic T lymphocytes in rats with experimental cholangitis - PubMed (original) (raw)