Blockade of IL-33R/ST2 Signaling Attenuates Toxoplasma gondii Ileitis Depending on IL-22 Expression

Oral T. gondii infection (30 cysts of 76K strain) induces acute lethal ileitis in sensitive C57BL/6 (B6) mice with increased expression of IL-33 and its receptor ST2 in the ileum. Here we show that IL-33 is involved in ileitis, since absence of IL-33R/ST2 attenuated neutrophilic inflammation and Th1 cytokines upon T. gondii infection with enhanced survival. Blockade of ST2 by neutralizing ST2 antibody in B6 mice conferred partial protection, while rmIL-33 aggravated ileitis. Since IL-22 expression further increased in absence of ST2, we blocked IL-22 by neutralizing antibody, which abrogated protection from acute ileitis in ST2 deficient mice. In conclusion, severe lethal ileitis induced by oral T. gondii infection is attenuated by blockade of ST2 signaling and may be mediated in part by endogenous IL-22

Role of IL-1β in experimental cystic fibrosis upon P. aeruginosa Infection

Cystic fibrosis is associated with increased inflammatory responses to pathogen challenge. Here we revisited the role of IL-1β in lung pathology using the experimental F508del-CFTR murine model on C57BL/6 genetic background (Cftrtm1eur or d/d), on double deficient for d/d and type 1 interleukin-1 receptor (d/d X IL-1R1-/-), and antibody neutralization. At steady state, young adult d/d mice did not show any signs of spontaneous lung inflammation. However, IL-1R1 deficiency conferred partial protection to repeated P. aeruginosa endotoxins/LPS lung instillation in d/d mice, as 50% of d/d mice succumbed to inflammation, whereas all d/d x IL-1R1-/- double mutants survived with lower initial weight loss and less pulmonary collagen and mucus production, suggesting that the absence of IL-1R1 signaling is protective in d/d mice in LPS-induced lung damage. Using P. aeruginosa acute lung infection we found heightened neutrophil recruitment in d/d mice with higher epithelial damage, increased bacterial load in BALF, and augmented IL-1β and TNF-α in parenchyma as compared to WT mice. Thus, F508del-CFTR mice show enhanced IL-1β signaling in response to P. aeruginosa. IL-1β antibody neutralization had no effect on lung homeostasis in either d/d or WT mice, however P. aeruginosa induced lung inflammation and bacterial load were diminished by IL-1β antibody neutralization. In conclusion, enhanced susceptibility to P. aeruginosa in d/d mice correlates with an excessive inflammation and with increased IL-1β production and reduced bacterial clearance. Further, we show that neutralization of IL-1β in d/d mice through the double mutation d/d x IL-1R1-/- and in WT via antibody neutralization attenuates inflammation. This supports the notion that intervention in the IL-1R1/IL-1β pathway may be detrimental in CF patients

Critical role of IL-33 receptor ST2 in experimental cerebral malaria development

International audienc

IL-1R1-MyD88 axis elicits papain-induced lung inflammation

Allergic asthma is characterized by a strong Th2 response with inflammatory cell recruitment and structural changes in the lung. Papain is a protease allergen disrupting the airway epithelium triggering a rapid inflammation with eosinophilia mediated by innate lymphoid cell activation (ILC2) and leading to a Th2 immune response. In this study, we focused on inflammatory responses to a single exposure to papain and showed that intranasal administration of papain results in the recruitment of inflammatory cells, including neutrophils and eosinophils with a rapid production of IL-1α, IL-1β, and IL-33. The inflammatory response is abrogated in the absence of IL-1R1 and MyD88. To decipher the cell type(s) involved in MyD88-dependent IL-1R1/MyD88 signaling, we used new cell-specific MyD88-deficient mice and found that the deletion of MyD88 signaling in single cell types such as T cells, epithelial cells, CD11c-positive or myeloid cells leads to only a partial inhibition compared to complete absence of MyD88, suggesting that several cell types contribute to the response. Importantly, the inflammatory response is largely ST2 and IL-36R independent. In conclusion, IL-1R1 signaling via MyD88 is critical for the first step of inflammatory response to papain

Anti-IL-1β antibody treatment has no significant effect on lung ultrastructure, nor on IL-1β, IL-6 and CCL2 mRNA production in lungs.

<p>Wild type (WT) and F508del CFTR mutation homozygote (d/d) mice (14-week-old females and males) were treated intra-peritoneally, once a week for 8 weeks, an anti-IL-1β antibody (10 mg/kg), or PBS. Mice were euthanatized 1 week after the last treatment and lung structure was observed on H&E stained slides observed at ×20 magnification (A). Cellular infiltration (B) was quantified on these H&E slides and mucus production (C) was analyzed on CAB stained lung slides. Lung injury score was recorded in anti-IL-1β antibody treated mice compared with PBS treated mice. (D and E) mRNA production of IL-1β, IL-6 and CCL2 was measured, and normalized with 2 housekeeping gene expression (<i>Hprt1</i> and <i>Gapdh</i>). The effect of anti-IL-1β antibody treatment compared to PBS control in WT and d/d animals is shown in (D), and the effect of F508del CFTR mutation compared to WT is shown in (E). (n = 6–7)</p

IL-1β participates in <i>P. aeruginosa</i>-induced inflammation at 20 h in WT mice.

<p>WT mice received 10⁶ CFU of <i>P. aeruginosa</i> PA011 intranasally, and WT mice treated with NaCl 0.9% were used as control. A group of WT mice was also treated intraperitoneally with anti-IL-1β antibody, 200 µg/mice, 15 h and 1 h before infection. Body weight variation 20 h after infection is shown in (A). Bacterial load was determined in BALF and in lung homogenate (B), myeloperoxidase activity was quantified (C) and absolute numbers of cells, (macrophages and neutrophils) were measured in BALF (D). Protein concentration was evaluated in BALF (E) and IL-1β (F), KC (G), TNF-α (H) and IL-6 (I), were measured in BALF and in lung homogenate. Cell infiltration was observed on H&E stained slide (J) and scored (K). (n = 5–6) Values are in mean +/− SEM; * for p<0.05; ** for p<0.01 and *** for p<0.001. ns for non-significant.</p

<i>P. aeruginosa</i> infection induces an increased inflammation in d/d mice.

<p>WT and d/d mice received 2×10⁵ CFU of <i>P. aeruginosa</i> PA011 intranasally, and WT mice treated with NaCl 0.9% were used as control. Body weight variation 20 h after infection is shown in (A). Myeloperoxidase activity was quantified (B) and absolute numbers of cells; (macrophages and neutrophils) were measured in BALF (C). Bacterial load (total CFU) was determined in BALF and in lung homogenate (D). Total protein concentration was evaluated in BALF (E) and KC (F), IL-1β (G) and TNF-α (H) were measured in lung homogenate. Cell infiltration was observed on H&E stained slide (I) and scored (J). (n = 5–6) Values are in mean +/− SEM; * for p<0.05; ** for p<0.01 and *** for p<0.001. ns for non-significant.</p

IL-1β participates in pathologic inflammation in F508del CFTR mutants, in response to <i>P. aeruginosa</i> LPS.

<p>d/d and double KO d/d x IL-1R1^−/− mice were treated intranasally with 80 µg of <i>P. aeruginosa</i> endotoxins/LPS in 40 µL PBS, once a week for 5 weeks. Untreated WT mice (UT) were used as control. Survival is presented in (A) and body weight variation 24 h after the last LPS challenge in (B). Absolute numbers of cells, (macrophages, lymphocytes and neutrophils) were measured in BALF 24 h after the last LPS challenge (C). CCL2 (D), IL-6 (E) and IL-1β (F) were measured in lung homogenate. Cell infiltration was observed on H&E staining (G), mucus production on PAS staining (H) and collagen deposition on CAB staining (I). Histopathological scores are shown in (J). n = 6–7 initially, n = 3 for d/d+LPS mice 24 h after last challenge instillation. Values are in mean +/− SEM; * for p<0.05 and ns for non-significant.</p