AMD3100, a CxCR4 antagonist, attenuates allergic lung inflammation and airway hyperreactivity

Abstract

The role of specific chemokine receptors during allergic asthmatic responses has been relatively undefined. A number of receptors are preferentially expressed on Th2 cells, including CCR4, CCR8, and CxCR4. In the present study, we have examined the role of CxCR4 in the development of cockroach allergen-induced inflammation and airway hyperreactivity in a mouse model of asthma. Using a specific inhibitor of CxCR4, AMD3100, our results indicate that blocking this receptor has a significant effect in down-regulating the inflammation and pathophysiology of the allergen-induced response. Treatment of allergic mice with AMD3100 significantly reduced airway hyperreactivity, peribronchial eosinophilia, and the overall inflammatory responses. In addition, there was a shift in the cytokine profile that was observed in the AMD3100-treated animals. Specifically, there was a significant reduction in interleukin-4 and interleukin-5 levels and a significant increase in interleukin-12 and interferon-gamma levels within the lungs of treated allergic mice. Furthermore, there was a significant alteration in the local chemokine production of CCL22 (MDC) and CCL17 (TARC), two chemokines previously shown to be important in Th2-type allergen responses. Overall, specifically blocking CxCR4 using AMD3100 reduced a number of pathological parameters related to asthmatic-type inflammation.

Figure 1.

AMD3100 treatment significantly reduces development of AHR. Animals sensitized and challenged with cockroach allergen were given various doses of AMD3100 and assessed for development of airway hyperreactivity 24 hours after challenge. The data represents means ± SE from five to six mice per group.

Figure 2.

Inhibition of CxCR4 with AMD3100 during chronic allergic responses significantly attenuates airway hyperreactivity in allergic mice. Animals were implanted intraperitoneally with a 3-day osmotic pump that delivered 250 μg/kg/hour of AMD3100 or the saline vehicle. The cockroach allergen-sensitized mice were given two antigenic airway challenges 48 hours apart and assessed for airway hyperreactivity 24 hours after the final allergen challenge. The data represent means ± SE from six mice in each group. Control nonallergic mice treated for 3 days with Alzet pumps containing either AMD3100 or saline followed by an allergen challenge had no alteration of AHR compared to untreated control mice (airway resistance range was between 2.5 and 4.0 cmH₂O/ml/second).

Figure 3.

Allergic animals treated with AMD3100 have a significant reduction in eosinophil accumulation in and around the airway. Chronically treated allergic animals from Figure 2 ▶ were assessed for the level of eosinophil recruitment into the airway and lungs by examining the levels in bronchoalveolar lavage fluid (A) and enumerating the peribronchial eosinophils morphometrically (B). The total numbers of bronchoalveolar lavage leukocytes were 2.3 ± 1 × 10 for control and 1.9 ± 2.0 × 10 for AMD3100. The data represent the means ± SE for six mice in each group. Nonallergic control mice treated in a similar manner followed by a cockroach allergen challenge had minimal peribronchial eosinophil accumulation (<10 eosinophils/100 high-powered fields).

Figure 4.

Inhibition of CxCR4 with AMD3100 during chronic allergic responses significantly attenuates the overall airway inflammatory responses. The photo represents the significant reduction in the leukocyte recruitment responses in the lungs of the allergic mice.

Figure 5.

Blocking CxCR4 significantly reduced the accumulation of total leukocytes in the lungs of allergic mice (A) and significantly altered the level of CD4 + cell recruitment (B). Lungs from chronically allergen-challenged mice treated with AMD3100 (250 μg/kg/hour) or saline were dispersed by collagenase treatment and the single-cell suspensions assessed for leukocyte numbers and subset analysis by flow cytometry. Data represents means ± SE from four mice in each group.

Figure 6.

Alteration of cytokine profiles in allergic animals treated with AMD3100. The Th1- and Th2-associated cytokines, IL-12 (p40), IFN-γ (Th1 type), and IL-4 and IL-5 (Th2 type) were assayed in whole-lung homogenates of chronically challenged allergic mice by specific ELISA. The data represents means ± SE from five mice in each group. *, P < 0.05.

Figure 7.

Reduction of chemokine production in the lungs of allergic mice treated with AMD3100. CCL11, CCL17, and CCL22 levels were assessed in the lung homogenates from mice treated with either AMD3100 (250 μg/kg/hour) or saline using specific ELISAs. The data represents means ± SE from five mice in each group. *, P < 0.05.