High IFN-γ and low SLPI mark severe asthma in mice and humans
Mahesh Raundhal, Christina Morse, Anupriya Khare, Timothy B. Oriss, Jadranka Milosevic, John Trudeau, Rachael Huff, Joseph Pilewski, Fernando Holguin, Jay Kolls, Sally Wenzel, Prabir Ray, Anuradha Ray
Mahesh Raundhal, Christina Morse, Anupriya Khare, Timothy B. Oriss, Jadranka Milosevic, John Trudeau, Rachael Huff, Joseph Pilewski, Fernando Holguin, Jay Kolls, Sally Wenzel, Prabir Ray, Anuradha Ray
View: Text | PDF | Corrigendum
Research Article Pulmonology

High IFN-γ and low SLPI mark severe asthma in mice and humans

Abstract

Severe asthma (SA) is a challenge to control, as patients are not responsive to high doses of systemic corticosteroids (CS). In contrast, mild-moderate asthma (MMA) is responsive to low doses of inhaled CS, indicating that Th2 cells, which are dominant in MMA, do not solely orchestrate SA development. Here, we analyzed broncholalveolar lavage cells isolated from MMA and SA patients and determined that IFN-γ (Th1) immune responses are exacerbated in the airways of individuals with SA, with reduced Th2 and IL-17 responses. We developed a protocol that recapitulates the complex immune response of human SA, including the poor response to CS, in a murine model. Compared with WT animals, Ifng–/– mice subjected to this SA model failed to mount airway hyperresponsiveness (AHR) without appreciable effect on airway inflammation. Conversely, AHR was not reduced in Il17ra–/– mice, although airway inflammation was lower. Computer-assisted pathway analysis tools linked IFN-γ to secretory leukocyte protease inhibitor (SLPI), which is expressed by airway epithelial cells, and IFN-γ inversely correlated with SLPI expression in SA patients and the mouse model. In mice subjected to our SA model, forced SLPI expression decreased AHR in the absence of CS, and it was further reduced when SLPI was combined with CS. Our study identifies a distinct immune response in SA characterized by a dysregulated IFN-γ/SLPI axis that affects lung function.

Authors

Mahesh Raundhal, Christina Morse, Anupriya Khare, Timothy B. Oriss, Jadranka Milosevic, John Trudeau, Rachael Huff, Joseph Pilewski, Fernando Holguin, Jay Kolls, Sally Wenzel, Prabir Ray, Anuradha Ray

×

Figure 2

Establishment of a mouse model of SA.

Options: View larger image (or click on image) Download as PowerPoint
Establishment of a mouse model of SA. (A) Schematics of the models of as...
(A) Schematics of the models of asthma used in the study. Mice were sensitized and challenged as shown either with or without Dex treatment, and 24 hours after the last allergen challenge, mice were euthanized and analyzed for different end points. (B) Assessment of central airway resistance (Newtonian resistance [Rn]) as a marker of AHR after challenge with different doses of MCh. ****P ≤ 0.0001, versus naive mice; ††††P < 0.0001, SA versus MA Th1loTh2; ###P < 0.001, SA versus SA plus Dex; #P < 0.05, MA Th1loTh2 versus MA Th1loTh2 plus Dex using 1-way ANOVA with Tukey’s post hoc test. (C) Differential cell counts in BAL fluid cytospins showing total cells, eosinophils (Eos), macrophages (Macs), neutrophils (Neu), and lymphocytes (Lymph) of mice sensitized and challenged in SA and MA Th1loTh2 models ± Dex. **P ≤ 0.01; ***P ≤ 0.001, Student’s unpaired t test. (D) PAS staining of lung sections. Scale bar: 200 mm. Data shown are mean ± SEM and representative of 2 to 3 independent experiments. n = 8–16 mice (B); n = 3–4 mice (C and D).