Mechanisms driving persistent airway inflammation in chronic obstructive pulmonary disease (COPD) are incompletely understood. As secretory immunoglobulin A (SIgA) deficiency in small airways has been reported in COPD patients, we hypothesized that immunobarrier dysfunction resulting from reduced SIgA contributes to chronic airway inflammation and disease progression. Here we show that polymeric immunoglobulin receptor-deficient (pIgR−/−) mice, which lack SIgA, spontaneously develop COPD-like pathology as they age. Progressive airway wall remodelling and emphysema in pIgR−/− mice are associated with an altered lung microbiome, bacterial invasion of the airway epithelium, NF-κB activation, leukocyte infiltration and increased expression of matrix metalloproteinase-12 and neutrophil elastase. Re-derivation of pIgR−/− mice in germ-free conditions or treatment with the anti-inflammatory phosphodiesterase-4 inhibitor roflumilast prevents COPD-like lung inflammation and remodelling. These findings show that pIgR/SIgA deficiency in the airways leads to persistent activation of innate immune responses to resident lung microbiota, driving progressive small airway remodelling and emphysema.

By crossing LysM-Cre and TGF-β type II receptor (Tgfbr2) floxed mice we achieved specific deletion of Tgfbr2 in myeloid cells (Tgfbr2(MyeKO) mice). S.c.-injected (LLC, EL4-OVA) and implanted (MMTV-PyMT) carcinoma cells grow slower in Tgfbr2(MyeKO) mice. The number of CD45(+) cells in the tumor tissue was the same in both genotypes of mice, but upon analysis, the percentage of T cells (CD45(+)CD3(+)) in the KO mice was increased. By flow cytometry analysis, we did not detect any differences in the number and phenotype of TAMs, CD11b(+)Gr1(+), and DCs in Tgfbr2(MyeKO) compared with Tgfbr2(MyeWT) mice. ELISA and qRT-PCR data showed differences in myeloid cell functions. In Tgfbr2(MyeKO) TAMs, TNF-α secretion was increased, basal IL-6 secretion was down-regulated, TGF-β did not induce any VEGF response, and there was decreased MMP9 and increased MMP2 and iNOS expression. TGF-β did not have any effect on CD11b(+)Gr1(+) cells isolated from Tgfbr2(MyeKO) mice in the regulation of Arg, iNOS, VEGF, and CXCR4, and moreover, these cells have decreased suppressive activity relative to T cell proliferation. Also, we found that DCs from tumor tissue of Tgfbr2(MyeKO) mice have increased antigen-presented properties and an enhanced ability to stimulate antigen-specific T cell proliferation. We conclude that Tgfbr2 in myeloid cells has a negative role in the regulation of anti-tumorigenic functions of these cells, and deletion of this receptor decreases the suppressive function of CD11b(+)Gr1(+) cells and increases antigen-presenting properties of DCs and anti-tumorigenic properties of TAMs.

Solute carrier family 7 member 2 (SLC7A2, also known as CAT2) is an inducible transporter of the semi-essential amino acid L-arginine (L-Arg), which has been implicated in wound repair. We have reported that both SLC7A2 expression and L-Arg availability are decreased in colonic tissues from inflammatory bowel disease patients and that mice lacking Slc7a2 exhibit a more severe disease course when exposed to dextran sulfate sodium (DSS) compared to wild-type (WT) mice. Here, we present evidence that SLC7A2 plays a role in modulating colon tumorigenesis in the azoxymethane (AOM)-DSS model of colitis-associated carcinogenesis (CAC). SLC7A2 was localized predominantly to colonic epithelial cells in WT mice. Utilizing the AOM-DSS model, Slc7a2 mice had significantly increased tumor number, burden, and risk of high-grade dysplasia vs. WT mice. Tumors from Slc7a2 mice exhibited significantly increased levels of the proinflammatory cytokines/chemokines IL-1β, CXCL1, CXCL5, IL-3, CXCL2, CCL3, and CCL4, but decreased levels of IL-4, CXCL9, and CXCL10 compared to tumors from WT mice. This was accompanied by a shift toward pro-tumorigenic M2 macrophage activation in Slc7a2-deficient mice, as marked by increased colonic CD11bF4/80ARG1 cells with no alteration in CD11bF4/80NOS2 cells by flow cytometry and immunofluorescence microscopy. The shift toward M2 macrophage activation was confirmed in bone marrow-derived macrophages from Slc7a2 mice. In bone marrow chimeras between Slc7a2 and WT mice, the recipient genotype drove the CAC phenotype, suggesting the importance of epithelial SLC7A2 in abrogating neoplastic risk. These data reveal that SLC7A2 has a significant role in the protection from CAC in the setting of chronic colitis, and suggest that the decreased SLC7A2 in inflammatory bowel disease (IBD) may contribute to CAC risk. Strategies to enhance L-Arg availability by supplementing L-Arg and/or increasing L-Arg uptake could represent a therapeutic approach in IBD to reduce the substantial long-term risk of colorectal carcinoma.

Wilms' tumor (WT) is the most common childhood renal cancer. Although mutations in known tumorassociated genes (WT1, WTX , and CATNB) occur only in a third of tumors, many tumors show evidence of activated ␤-catenin-dependent Wnt signaling, but the molecular mechanism by which this occurs is unknown. A key obstacle to understanding the pathogenesis of WT is the paucity of mouse models that recapitulate its features in humans. Herein, we describe a transgenic mouse model of primitive renal epithelial neoplasms that have high penetrance and mimic the epithelial component of human WT. Introduction of a stabilizing ␤-catenin mutation restricted to the kidney is sufficient to induce primitive renal epithelial tumors; however, when compounded with activation of K-RAS, the mice develop large, bilateral, Wilms' tumor (WT) is an embryonal tumor of the kidney that is the most common childhood renal cancer and the fourth most common childhood malignancy overall. 1,2Modern multimodal management can cure 95% of patients with WT with the most favorable risk profile 3-7 but at the cost of significant short-and long-term morbidity. -11In addition, there remains a persistent cohort of children who ultimately fail therapy and die.3 Consequently, the main research priorities for WT are to lower the toxicity while maintaining efficacy of existing therapy for lowerrisk patients and to develop novel therapeutics for higherrisk patients. Achieving these goals depends on understanding the mechanisms underlying WT oncogenesis and progression.WTs are triphasic, embryonic tumors that classically have varying amounts of blastemal elements, primitive mesenchymal stroma, and primitive epithelia. They are generally thought to arise from nephrogenic rests (ie, embryonic tissue) derived from the metanephric mesenchyme during renal development. The genetic aberrations underlying this process are known to be heterogeneous 12 and can include inactivating mutations of Wilms' tumor 1 gene (WT1), 13,14 Wilms' tumor gene found on chromosome X (WTX), [15][16][17] and stabilizing/activating mutations of ␤-catenin (CTNNB1). 18,19 The precise mechaSupported in part by NIH grants K08 CA113452 (P.E.C.), DK065123 (R.Z.), DK075594 (R.Z.), DK65123 (R.Z.), and P30 DK079341 (P.E.C. and R.Z.); an American Heart Association Established Investigator Award (R.Z.); and a Merit Award from the Department of Veterans Affairs (R.Z.).Accepted for publication August 10, 2011. CME Disclosure: None of the authors disclosed any relevant financial relationships.Address reprint requests to Peter E. Clark, M.D., Associate Professor Urologic Surgery, Vanderbilt University Medical Center, A-1302 Medical Center North, Nashville, TN 37232-2765. E-mail: peter.clark@ vanderbilt.edu.

Wilms tumor (WT) is the most common renal neoplasm of childhood and affects 1 in 10 000 children aged less than 15 years. These embryonal tumors are thought to arise from primitive nephrogenic rests that derive from the metanephric mesenchyme during kidney development and are characterized partly by increased Wnt/β‐catenin signaling. We previously showed that coordinate activation of Ras and β‐catenin accelerates the growth and metastatic progression of a murine WT model. Here, we show that activating KRAS mutations can be found in human WT. In addition, high levels of phosphorylated AKT are present in the majority of WT. We further show in a mouse model and in renal epithelial cells that Ras cooperates with β‐catenin to drive metastatic disease progression and promotes in vitro tumor cell growth, migration, and colony formation in soft agar. Cellular transformation and metastatic disease progression of WT cells are in part dependent on PI3K/AKT activation and are inhibited via pharmacological inhibition of this pathway. Our studies suggest both KRAS mutations and AKT activation are present in WT and may represent novel therapeutic targets for this disease.