Highlights d P. aeruginosa keratitis infections result in biofilm formation on the cornea d NETs form at the base of the biofilm, triggered by the type-3 secretion system (T3SS) d NETs stop bacterial dissemination into the brain but promote antibiotic resistance d Blocking exopolysaccharide Psl and the T3SS allowed neutrophils to break down the biofilm

Inflammatory mediators are of considerable interest as potential therapeutic targets in various cancers. Here we investigate whether interleukin (IL)-4 receptor alpha (IL4Ralpha), a component of the receptor complex for the T helper 2 cytokines IL4 and IL13, plays a role in colonic tumorigenesis. IL4Ralpha protein expression was seen in tumor cells of 28/48 human colon adenocarcinomas on a tissue microarray. In human and murine colon tumor cell lines analyzed in vitro, all of which expressed IL4Ralpha, treatment with exogenous ligand resulted in dose-dependent increases in proliferation. IL4 decreased apoptosis only in HCT116 cells. An orthotopic allograft model was used to determine in vivo effects of tumor cell-specific IL4Ra ablation. MC38 murine tumor cells with the IL4Ra gene knocked down showed reduced proliferation but no difference in apoptosis compared with controls after implantation in ceca of syngeneic mice. Mice null for IL4Ra and wild-type controls were treated with azoxymethane and dextran sulfate sodium to induce tumor formation. Mice with global deletion of IL4Ra had significantly fewer and smaller tumors. Reduced tumorigenicity correlated with decreased proliferation and increased apoptosis. Systemic blockade of IL4Ralpha-IL4 interactions with a chimeric soluble receptor protein gave similar results in the cecal implant model. Thus, IL4Ralpha, a component of the IL4R and IL13R, contributes to tumor formation in a mouse model of colitis-associated cancer. Proliferation appears to be directly mediated via IL4Ralpha on the epithelial tumor cells. Survival may be an indirect response mediated via other host cells. Our results support therapeutic targeting of IL4Ralpha in colon cancer.

Interleukin-4 (IL4), a cytokine produced mainly by immune cells, may promote the growth of epithelial tumors by mediating increased proliferation and survival. Here, we show that the type II IL4 Receptor (IL4R) is expressed and activated in human breast cancer and mouse models of breast cancer. In metastatic mouse breast cancer cells, RNAi-mediated silencing of IL4Rα, a component of the IL4 receptor, was sufficient to attenuate growth at metastatic sites. Similar results were obtained with control tumor cells in IL4-deficient mice. Decreased metastatic capacity of IL4Rα “knockdown” (KD) cells was attributed in part to reductions in proliferation and survival of breast cancer cells. Additionally, we observed an overall increase in immune infiltrates within IL4Rα KD tumors, indicating that enhanced clearance of KD tumor cells could also contribute to the reduction in KD tumor size. Pharmacological investigations suggested that IL4-induced cancer cell colonization was mediated in part by activation of Erk1/2, Akt and mTor. Reduced levels of pAkt and pErk1/2 in IL4Rα KD tumor metastases were associated with limited outgrowth, supporting roles for Akt and Erk activation in mediating the tumor-promoting effects of IL4Rα. Collectively, our results offer a preclinical proof of concept for targeting IL4/IL4Rα signaling as a therapeutic strategy to limit breast cancer metastasis.

Inflammatory bowel diseases such as ulcerative colitis represent serious health burdens, both because of the tissue-damaging disease itself, and because of an elevated risk of colon cancer. The increased expression of many members of the matrix metalloproteinase (MMP) family of enzymes that occurs in colitis, has long been associated with the destructive nature of the disease. Recent findings in cancer and other MMP-associated diseases, however, led us to question whether MMPs are indeed detrimental in the setting of colitis. Here, we focus on a single MMP family member, MMP10, and assess its role in a murine model of colonic tissue damage induced by dextran sulphate sodium (DSS) treatment. Using mice genetically deficient for MMP10, we find that absence of this enzyme leads to significantly worse disease scores and failure to resolve inflammation even after extended recovery periods. We show that MMP10 is produced predominantly by infiltrating myeloid cells in both murine and human colitis. Through bone marrow transplant experiments, we confirm that bone marrow-derived MMP10 contributes to colitis severity. Mice lacking MMP10 have a significantly higher propensity for development of dysplastic lesions in the colon after two rounds of DSS exposure. Thus, we conclude that MMP10 is required for resolution of DSS-induced colonic damage, and in its absence, chronic inflammation and ultimately dysplasia occurs.

Breast cancer survival rates decrease from 99% for patients with local disease to 25% for those with distant metastases. Matrix metalloproteinases (MMPs), including MMP2, are associated with metastatic progression. We found that loss of host MMP2 reduces the proliferation of experimental metastases in the lungs and identified fibroblasts in tumour-bearing lungs as the major source of MMP2. In vitro, spheroidal mammary tumour growth was increased by co-culture with control fibroblasts isolated from tumour-bearing lungs but not when fibroblasts with stable Mmp2 knockdown were used. This result prompted us to assess whether MMP2 was responsible for a tumour-proliferative, activated fibroblast phenotype. To test this, we evaluated (i) fibroblasts from wild-type tumour-bearing lungs with or without shRNA-mediated MMP2 knockdown and (ii) normal, quiescent fibroblasts isolated from either WT or Mmp2−/− mice. Quantitative PCR revealed that Mmp2 knockdown attenuated expression of two markers of activation (α-smooth muscle actin and vimentin), but there was minimal expression in quiescent WT or Mmp2−/− fibroblasts, as expected. Placing quiescent fibroblasts under activating conditions led to increases in activation-associated transcripts in WT but not Mmp2−/− fibroblasts. Additionally, Mmp2 knockdown fibroblasts showed significantly decreased expression of the matrix transcripts collagen I, collagen IV and fibronectin. Addition of active TGFβ was sufficient to rescue the MMP2-dependent collagen I and IV expression, while MMP2-induced collagen expression was blocked with addition of TGFβ-1 neutralizing antibody. Gene expression data in stromal cells of human breast cancers reveals that MMP2 expression is also positively correlated with activation and matrix transcripts. Thus, we present a model whereby MMP2 production in tumour fibroblasts is important for TGFβ-1 activity and subsequent activation of fibroblasts to a matrix-producing, proliferation-supportive phenotype. Overall, our results reveal a previously undefined role for MMP2 in metastatic outgrowth mediated by fibroblasts, and extend the mechanisms by which MMPs contribute to tumour progression.