Kam J C, Szefler S J, Surs W, Sher E R, Leung D Y
Division of Pediatric Allergy-Immunology, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.
J Immunol. 1993 Oct 1;151(7):3460-6.
The mechanisms contributing to persistent T cell activation and poor response to glucocorticoids in chronic inflammatory illnesses such as steroid resistant (SR) asthma are poorly defined. We examined the possibility that certain cytokines, specifically IL-2 and IL-4, could affect T cell response to glucocorticoids. A [3H]dexamethasone radioligand-binding assay was used to measure the number of glucocorticoid receptors (GR) and dissociation constant (Kd) in PBMC from normal donors and patients with SR asthma, cultured in the absence and presence of these cytokines. PBMC from normal donors incubated for 48 h in the presence of combination IL-2 + IL-4 had nuclear GR with significantly reduced binding affinity (GR Kd = 36.1 +/- 1.63 nM, mean +/- SEM; p = 0.0001) as compared with PBMC incubated with medium alone (GR Kd = 6.74 +/- 0.46 nM). The cytosolic GR Kd remained unchanged. However, when PBMC were incubated with IL-2 alone or IL-4 alone, no change in GR-binding affinity was observed. Furthermore, when T cells and non-T cells were individually stimulated with combination IL-2 + IL-4, a significant reduction in GR-binding affinity was observed only in the T cell population (p = 0.0001). The IL-2 + IL-4-induced alteration in PBMC GR Kd was associated with an increase in GR number (8348 +/- 964 vs 1710 +/- 228 sites/cell; p = 0.0003). More importantly, the alteration in PBMC GR-binding affinity with IL-2 + IL-4 was associated with a functional change in T cell response to methylprednisolone MPN, i.e., a reduced inhibitory effect of MPN on PMA/ionomycin-induced T cell proliferation. These effects of IL-2 + IL-4 on PBMC GR affinity and response to MPN were blocked by co-incubation with IFN-gamma. Freshly isolated PBMC from four patients with SR asthma had a significantly reduced GR-binding affinity (Kd = 40.0 +/- 2.68 nM; p = 0.0001) when compared with seven normal subjects (7.15 +/- 0.41 nM). The altered PBMC GR binding from patients with SR asthma reversed to normal when incubated with medium alone, but was sustained with IL-2 + IL-4. These observations suggest that with persistent inflammation certain cytokines may contribute to an impaired response to glucocorticoids. Furthermore, the effects of IL-2 and IL-4 were blocked by IFN-gamma.
在诸如激素抵抗（SR）性哮喘等慢性炎症性疾病中，导致T细胞持续活化以及对糖皮质激素反应不佳的机制尚不清楚。我们研究了某些细胞因子，特别是白细胞介素-2（IL-2）和白细胞介素-4（IL-4），是否会影响T细胞对糖皮质激素的反应。采用[3H]地塞米松放射性配体结合试验，测量正常供体和SR哮喘患者外周血单个核细胞（PBMC）中糖皮质激素受体（GR）的数量和解离常数（Kd），这些细胞分别在不存在和存在这些细胞因子的情况下进行培养。与单独用培养基培养的PBMC（GR Kd = 6.74 +/- 0.46 nM）相比，正常供体的PBMC在IL-2 + IL-4联合存在下孵育48小时后，其核GR的结合亲和力显著降低（GR Kd = 36.1 +/- 1.63 nM，平均值 +/- 标准误；p = 0.0001）。胞质GR的Kd保持不变。然而，当PBMC单独与IL-2或IL-4孵育时，未观察到GR结合亲和力的变化。此外，当T细胞和非T细胞分别用IL-2 + IL-4联合刺激时，仅在T细胞群体中观察到GR结合亲和力显著降低（p = 0.0001）。IL-2 + IL-4诱导的PBMC GR Kd变化与GR数量增加相关（8348 +/- 964对1710 +/- 228位点/细胞；p = 0.0003）。更重要的是，PBMC与IL-2 + IL-4的GR结合亲和力变化与T细胞对甲泼尼龙（MPN）反应的功能变化相关，即MPN对佛波酯/离子霉素诱导的T细胞增殖的抑制作用减弱。IL-2 + IL-4对PBMC GR亲和力和对MPN反应的这些作用可通过与干扰素-γ（IFN-γ）共同孵育而被阻断。与7名正常受试者（7.15 +/- 0.41 nM）相比，4名SR哮喘患者新鲜分离的PBMC的GR结合亲和力显著降低（Kd = 40.0 +/- 2.68 nM；p = 0.0001）。SR哮喘患者PBMC的GR结合改变在单独用培养基孵育时恢复正常，但在IL-2 + IL-4存在下则持续存在。这些观察结果表明，在持续炎症状态下，某些细胞因子可能导致对糖皮质激素的反应受损。此外，IL-2和IL-4的作用可被IFN-γ阻断。
